Group 5 KFUPM - Final

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Acknowledgment We, Group 5, would like to thank ourselves for the marvelous work that has been done in this report. Also, we express our respect and appreciation to Dr. Eid Almutairi for his fruitful guidance throughout this semester, and special thanks to all instructors who helped us, namely, Dr. Usama Ahmed and Dr. Umer Zahid.

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Table of Contents Executive Summary ...................................................................................... 15 Introduction ................................................................................................ 16 Literature Review ............................................................................................ 18 Problem Statement ....................................................................................... 19 Commercial Analysis, Production, and Technologies Used .................................. 20 Alternative Processes and Raw Materials ......................................................... 24 Methanol to Olefins Process ....................................................................................................... 24 Olefin Metathesis ........................................................................................................................ 25 Reaction Kinetics, Catalyst, and Equilibrium ..................................................... 26 Process Flow Diagram (PFD) .......................................................................... 28 Physical and Chemical Properties .................................................................... 29 Hydrogen ..................................................................................................................................... 29 Methane ...................................................................................................................................... 30 Ethane ......................................................................................................................................... 31 Ethylene ...................................................................................................................................... 32 Propane ....................................................................................................................................... 33 Iso-Butane ................................................................................................................................... 34 Propylene .................................................................................................................................... 35 Butane ......................................................................................................................................... 36 Butylene....................................................................................................................................... 37 Safety and Environment Information .............................................................. 38 Operational Safety....................................................................................................................... 38 Accidents Response..................................................................................................................... 38 Workers Education ..................................................................................................................... 39 Bowtie Diagram........................................................................................................................... 39 NFPA of Each Component .......................................................................................................... 40 Hydrogen ..................................................................................................................................... 40 Methane ...................................................................................................................................... 40 Ethane ......................................................................................................................................... 41 Ethylene ...................................................................................................................................... 41

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Propane ....................................................................................................................................... 42 Propylene .................................................................................................................................... 42 Butane ......................................................................................................................................... 43 Iso-Butane ................................................................................................................................... 43 1-Butene ...................................................................................................................................... 44 Preliminary Cost of The Materials and Profit Margin .......................................... 44 References .................................................................................................. 46 Mass & Energy Balance .................................................................................... 47 Introduction ................................................................................................ 48 Calculations ................................................................................................. 50 Material Balance Around the Reactor ........................................................................................ 50 Block Flow Diagram (BFD) for The Reactor ......................................................................................................... 51 Material Balance for Propylene .......................................................................................................................... 52 Material Balance for Propane ............................................................................................................................. 52 Material Balance for Ethylene............................................................................................................................. 52 Material Balance for Hydrogen ........................................................................................................................... 52 Material Balance for Methane ............................................................................................................................ 53 Material Balance for Ethane ............................................................................................................................... 53 Total Outlet of the Reactor ................................................................................................................................. 53 Mole Fractions of The Reactor Outlet................................................................................................................. 53

Energy Balance Around the Reactor........................................................................................... 54 Material Balance Around Distillation Column (T-101) .............................................................. 55 Overall Mass Balance .......................................................................................................................................... 55

Energy Balance Around Distillation Column (T-101) ................................................................ 56 Overall Energy Balance ....................................................................................................................................... 56

Material Balance Around Distillation Column (T-102).............................................................. 57 Overall Mass Balance .......................................................................................................................................... 57

Energy Balance Around Distillation Column (T-102) ................................................................ 59 Overall Energy Balance ....................................................................................................................................... 59

Flash Drum Mass Balance .......................................................................................................... 60 Overall Mass Balance .......................................................................................................................................... 61

Material Balance Around Distillation Column (T-103).............................................................. 62 Overall Mass Balance .......................................................................................................................................... 62

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Energy Balance Around Distillation Column (T-103) ................................................................ 63 Overall Energy Balance ....................................................................................................................................... 63

Material and Energy Balance Around Compressors .................................................................. 64 Work Calculation for C-101 ................................................................................................................................. 64

Material and Energy Balance Around Heat Exchangers ............................................................ 66 Energy Balance for Heat Exchanger (E-105)(Cooling Side) ................................................................................. 67

Material and Energy Balance Around Cooler ............................................................................. 68 Material and Energy Balance Around Fired Heater H-101 ........................................................ 69 Material and Energy Balance Around Pump .............................................................................. 70 References .................................................................................................. 73 Simulation ..................................................................................................... 74 Introduction ................................................................................................ 75 Fluid Package............................................................................................... 75 Process Flow Diagram (PFD) .......................................................................... 76 Plug Flow Reactor (R-101, R-102, R-103, and R-104) ....................................... 77 Plug Flow Reactor (R-101) ............................................................................. 77 Plug Flow Reactor (R-102) ............................................................................. 79 Plug Flow Reactor (R-103) ............................................................................. 81 Plug Flow Reactor (R-104) ............................................................................. 83 Case Studies ................................................................................................ 85 Case I: Effect of Changing Temperature of The Reactors ................................................................................... 85 Case II: Effect of Changing Pressure of The Reactors.......................................................................................... 86 Case III: Effect of Changing Volume of The Reactors .......................................................................................... 88

Distillation Columns (T-101, T-102, T-103) & Flash Drum (V-101) ...................... 90 Depropanizer (T-101) .................................................................................................................. 90 Flash Drum (V-101)..................................................................................................................... 93 Deethanizer (T-102) .................................................................................................................... 95 Propane/Propylene Splitter (T-103)........................................................................................... 97 Heat Exchangers .......................................................................................... 99 Heating Side ...................................................................................................................................................... 100 Cooling side ....................................................................................................................................................... 100

Heat Exchanger Series (E-102, E-103, E-104, and E-105) ....................................................... 100

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Heating Side ...................................................................................................................................................... 104 Cooling Side....................................................................................................................................................... 104

Coolers (E-106, E-107, E-108, and E-109) .....................................................105 Fired Heaters .............................................................................................. 107 Fired Heater (H-101)................................................................................................................. 107 Fired Heater (H-102) ................................................................................................................ 108 Fired Heater (H-103) ................................................................................................................ 109 Fired Heater (H-104) .................................................................................................................110 Compressors............................................................................................... 111 Compressor (C-101) ................................................................................................................... 111 Compressor (C-102, and C-103) ................................................................................................ 112 Equipment Design ..........................................................................................114 Reactor Design .............................................................................................. 115 Introduction ............................................................................................... 116 Design Assumptions .................................................................................................................. 116 Algorithm for Reactor sizing ...................................................................................................... 117 Mole Balance for Plug Flow Reactor .......................................................................................... 118 Rate Laws .................................................................................................................................. 120 Net rate laws............................................................................................................................... 121 Energy Balance.......................................................................................................................... 124 Thermodynamics Properties .................................................................................................... 125 Polymath Code and Results .......................................................................................................127 Reactor Dimensions .................................................................................................................. 132 Material of Construction ........................................................................................................... 134 Reactor Thickness ..................................................................................................................... 135 References .................................................................................................135 T-101, and T-103 Design ................................................................................136 Introduction ............................................................................................... 137 Depropanizer (T-101) ..................................................................................137 Mass Balance ..............................................................................................................................137 Fenske Equation ....................................................................................................................... 138

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Underwood Equation ................................................................................................................ 140 Second Underwood Equation.........................................................................141 Modified Fenske Equation ........................................................................................................ 143 Column Diameter (Enriching Section) ..................................................................................... 144 Vapor Velocity Flv .............................................................................................................................................. 145 Capacity factor Csb,f ........................................................................................................................................... 145 Flooding velocity uflood ....................................................................................................................................... 145

Column diameter D ................................................................................................................... 146 Column Diameter (Stripping Section) ...................................................................................... 146 Vapor Velocity Flv .............................................................................................................................................. 146 Capacity Factor Csb,f ........................................................................................................................................... 147 Column Diameter .............................................................................................................................................. 147

Column Height .......................................................................................................................... 147 Propane/Propylene splitter (T-103) ................................................................ 148 Mass Balance ............................................................................................................................. 148 Fenske Equation ....................................................................................................................... 149 Underwood Equation ................................................................................................................. 151 Second Underwood Equation ................................................................................................... 152 Modified Fenske Equation ........................................................................................................ 154 Column Diameter (Enriching Section) ......................................................................................155 Vapor Velocity Flv .............................................................................................................................................. 155 Capacity Factor Csb,f ........................................................................................................................................... 156 Flooding Velocity Uflood ...................................................................................................................................... 156 Column Diameter Dia ........................................................................................................................................ 157

Column Diameter (Stripping Section) ....................................................................................... 157 Vapor Velocity Flv .............................................................................................................................................. 157 Capacity Factor Csb,f ........................................................................................................................................... 157 Flooding Velocity Uflood ...................................................................................................................................... 158 Column Diameter Dia ........................................................................................................................................ 158

Column Height .......................................................................................................................... 158 Material of Construction (MOC)............................................................................................... 158 References .................................................................................................159 Vessel and T-102 Design ................................................................................160

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Introduction ............................................................................................... 161 Flash Drum (V-101) .....................................................................................161 Mass Balance .............................................................................................................................. 161 Distillation Column (T-102)...........................................................................164 Mass Balance ............................................................................................................................. 165 Mass Balance of Ethylene ................................................................................................................................. 165 Mass Balance of Propane .................................................................................................................................. 165 Mass Balance of Methane................................................................................................................................. 165 Mass Balance of Propylene ............................................................................................................................... 166

Fenske Equation ....................................................................................................................... 166 Fenske Equation ....................................................................................................................... 168 First Underwood Equation ....................................................................................................... 168 Modified Fenske Equation ........................................................................................................ 170 Column Diameter (Rectifying Section) ..................................................................................... 171 Vapor Velocity ................................................................................................................................................... 171 Capacity factor .................................................................................................................................................. 172 Column Diameter .............................................................................................................................................. 172 Flooding Velocity ............................................................................................................................................... 172

Column Diameter of Stripping Section .....................................................................................172 Vapor Velocity ................................................................................................................................................... 173 Capacity factor .................................................................................................................................................. 173 Column Diameter .............................................................................................................................................. 173

Column height ............................................................................................................................173 References .................................................................................................173 Heat Exchangers Design .................................................................................174 Introduction ............................................................................................... 175 Standards ................................................................................................................................... 175 Heat Exchanger Design Procedures ......................................................................................... 176 TUBE SIDE .......................................................................................................................................................... 178 Shell Side ........................................................................................................................................................... 182

Sample Calculations .................................................................................................................. 186 Tube Side ........................................................................................................................................................... 186 Shell Side ........................................................................................................................................................... 188

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Reboilers and Condenser Design .............................................................................................. 199 Safety for Heat Exchanger ........................................................................................................206 Fired Heaters............................................................................................................................. 207 Design Procedures .................................................................................................................... 207 Sample Calculations ................................................................................................................... 211 References .................................................................................................218 Piping Design ................................................................................................ 219 Introduction ............................................................................................... 220 Standards .................................................................................................................................. 220 Pipe Design ................................................................................................ 221 Material of Construction ........................................................................................................... 221 Methodology ............................................................................................................................. 223 Streams Information ................................................................................................................. 225 Sample Calculation ................................................................................................................... 226 Results of The Design ............................................................................................................... 228 Compressor Design .....................................................................................231 Methodology ............................................................................................................................. 231 Compressors Calculation .......................................................................................................... 232 Consideration of Safety ................................................................................233 Plant Layout ............................................................................................... 234 Summary ...................................................................................................235 References .................................................................................................235 Economics & Heat Integration .......................................................................236 Introduction ............................................................................................... 237 Assumption and Basis of The Calculation ................................................................................ 238 Compressors Calculation .......................................................................................................... 238 Bare Module Cost ........................................................................................239 Total Module and Grassroot Cost: ..................................................................240 Cost of Utility .............................................................................................. 241 Summary ...................................................................................................241

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Cash flow: Summary ...................................................................................243 Profitability Analysis ....................................................................................244 Discounted Cash Flow Rate of Return ............................................................. 245 Cumulative Cash Position .............................................................................245 Rate of Return on Investment .......................................................................246 Payback Period Data ....................................................................................246 Heat Integration ..........................................................................................247 Pinch Analysis ........................................................................................................................... 247 Composite Curve ....................................................................................................................... 249 Grid Diagram ............................................................................................................................ 250 Conclusion ..................................................................................................251 Recommendation ........................................................................................251

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Table of Figures FIGURE 1: BLOCK FLOW DIAGRAM (BFD) OF PROPANE DEHYDROGENATION PROCESS. .................................................................... 20 FIGURE 2: WORLD MAP SHOWING PDH INSTALLATIONS, PLANTS IN OPERATION, AND PLANTS UNDER CONSTRUCTION. ...........................21 FIGURE 3: PROPYLENE DERIVATIVES ............................................................................................................................................. 23 FIGURE 4: MTO PROCESS FLOW SCHEME. ................................................................................................................................... 24 FIGURE 5: METATHESIS OF ALKENES; R1, R2, R3, R4 = H, CH3, CH2CH3, ETC. .......................................................................... 25 FIGURE 6:TYPICAL FLOW SCHEME OF THE OCT METATHESIS PROCESS. ONLY ONE OF MULTIPLE REACTORS IS SHOWN.......................... 26 FIGURE 7: PROCESS FLOW DIAGRAM FOR PROPANE DEHYDROGENATION PROCESS (PDH). ............................................................... 28 FIGURE 8: HYDROGEN BALL AND STICK MODEL. ............................................................................................................................ 29 FIGURE 9: METHANE BALL AND STICK MODEL. .............................................................................................................................. 30 FIGURE 10: ETHANE BALL AND STICK MODEL. ................................................................................................................................31 FIGURE 11: ETHYLENE BALL AND STICK MODEL. ........................................................................................................................... 32 FIGURE 12: PROPANE BALL AND STICK MODEL. ............................................................................................................................. 33 FIGURE 13:ISO-BUTANE BALL AND STICK MODEL. ......................................................................................................................... 34 FIGURE 14: PROPYLENE BALL AND STICK MODEL. ......................................................................................................................... 35 FIGURE 15: BUTANE BALL AND STICK MODEL. ............................................................................................................................... 36 FIGURE 16: 1- BUTYLENE BALL AND STICK MODEL. ....................................................................................................................... 37 FIGURE 17: BOW-TIE DIAGRAM OF THE RISK ASSESSMENT OF THE TOXICITY OF THE MATERIALS. ........................................................ 39 FIGURE 18:BOW-TIE DIAGRAM OF THE RISK ASSESSMENT OF THE HEALTH RISKS OF THE MATERIALS................................................... 39 FIGURE 19: BOW-TIE DIAGRAM OF THE RISK ASSESSMENT OF THE FLAMMABILITY OF THE MATERIALS. ................................................ 40 FIGURE 20: BLOCK FLOW DIAGRAM OF PDH PROCESS. ................................................................................................................ 50 FIGURE 21: PDH REACTOR ..........................................................................................................................................................51 FIGURE 22: ILLUSTRATION OF THE FLASH DRUM.......................................................................................................................... 60 FIGURE 1: PFD OF THE COMPRESSORS........................................................................................................................................ 64 FIGURE 2: PFD OF THE HEAT EXCHANGERS ................................................................................................................................. 66 FIGURE 3: PFD OF THE COOLERS .............................................................................................................................................. 68 FIGURE 4: PFD OF THE PUMP ................................................................................................................................................... 70 FIGURE 23:FLUID PACKAGE SELECTION. ..................................................................................................................................... 75 FIGURE 24: PLUG FLOW REACTOR (R-101). ................................................................................................................................. 77 FIGURE 25: DIMENSIONS OF R-101. ............................................................................................................................................ 77 FIGURE 26: INLET COMPOSITIONS FOR EACH COMPONENT. ........................................................................................................... 78 FIGURE 27: OUTLET COMPOSITIONS FOR EACH COMPONENT ......................................................................................................... 78 FIGURE 28: PLUG FLOW REACTOR (R-102). ................................................................................................................................. 79 FIGURE 29: DIMENSIONS OF R-102. ............................................................................................................................................ 79 FIGURE 30: INLET COMPOSITIONS FOR EACH COMPONENT. ........................................................................................................... 79 FIGURE 31: OUTLET COMPOSITIONS FOR EACH COMPONENT ......................................................................................................... 80 FIGURE 32: PLUG FLOW REACTOR (R-103). ................................................................................................................................. 81 FIGURE 33: DIMENSIONS OF R-103. ............................................................................................................................................ 81 FIGURE 34: INLET COMPOSITIONS FOR EACH COMPONENT. ........................................................................................................... 81 FIGURE 35: OUTLET COMPOSITIONS FOR EACH COMPONENT ......................................................................................................... 82 FIGURE 36: PLUG FLOW REACTOR (R-104). ................................................................................................................................. 83 FIGURE 37: DIMENSIONS OF R-104 ............................................................................................................................................. 83 FIGURE 38: INLET COMPOSITIONS FOR EACH COMPONENT. ........................................................................................................... 83 FIGURE 39: OUTLET COMPOSITIONS FOR EACH COMPONENT ......................................................................................................... 84 FIGURE 40: CONVERSION VS TEMPERATURE. ............................................................................................................................... 85 FIGURE 41: SELECTIVITY VS TEMPERATURE. ............................................................................................................................... 86 FIGURE 42: CONVERSION VS PRESSURE. ..................................................................................................................................... 87

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FIGURE 43: SELECTIVITY VS PRESSURE....................................................................................................................................... 87 FIGURE 44: SELECTIVITY VS VOLUME......................................................................................................................................... 88 FIGURE 45: CONVERSION VS VOLUME. ....................................................................................................................................... 89 FIGURE 46: DEPROPANIZER (T-101). .......................................................................................................................................... 90 FIGURE 47: TEMPERATURE VS TRAY POSITION OF T-101. ............................................................................................................. 91 FIGURE 48: TEMPERATURE PROFILE. ........................................................................................................................................... 91 FIGURE 49: FIGURE 4: PRESSURE VS TRAY POSITION OF T-101. .................................................................................................... 91 FIGURE 50: PRESSURE PROFILE. .................................................................................................................................................. 92 FIGURE 51: COMPOSITIONS OF DISTILLATE OF T-101. .................................................................................................................. 92 FIGURE 52: HEAT DUTY FOR CONDENSER OF T-101. .................................................................................................................... 92 FIGURE 53: HEAT DUTY FOR REBOILER OF T-101......................................................................................................................... 92 FIGURE 54: FLASH DRUM (V-101). ............................................................................................................................................. 93 FIGURE 55: DEETHANIZER (T-102). ............................................................................................................................................ 95 FIGURE 56: TEMPERATURE PROFILE THROUGHOUT THE COLUMN. ................................................................................................ 95 FIGURE 57: PROPANE/PROPYLENE SPLITTER. .............................................................................................................................. 97 FIGURE 58: TEMPERATURE PROFILE. ........................................................................................................................................... 97 FIGURE 59: PRESSURE PROFILE. .................................................................................................................................................. 98 FIGURE 60: COMPOSITIONS OF DISTILLATE OF T-103. .................................................................................................................. 98 FIGURE 61: HEAT DUTY FOR CONDENSER OF T-103. .................................................................................................................... 98 FIGURE 62: HEAT DUTY FOR REBOILER OF T-103......................................................................................................................... 98 FIGURE 63: HEAT EXCHANGER E-101. ........................................................................................................................................ 99 FIGURE 64: DESIGN PARAMETERS OF E-101. ............................................................................................................................... 99 FIGURE 65: DETAILS OF E-102 PERFORMANCE. ........................................................................................................................... 99 FIGURE 66: HEAT EXCHANGERS E-102, E-103, E-104, AND E-105 RESPECTIVELY. ..................................................................... 100 FIGURE 67: DESIGN PARAMETERS OF E-102. .............................................................................................................................. 101 FIGURE 68: DETAILS OF E-102 PERFORMANCE. .......................................................................................................................... 101 FIGURE 69:DESIGN PARAMETERS OF E-103. ............................................................................................................................... 101 FIGURE 70: DETAILS OF E-103 PERFORMANCE. ......................................................................................................................... 102 FIGURE 71:DESIGN PARAMETERS OF E-104. .............................................................................................................................. 102 FIGURE 72: DETAILS OF E-104 PERFORMANCE. ......................................................................................................................... 102 FIGURE 73:DESIGN PARAMETERS OF E-105. .............................................................................................................................. 103 FIGURE 74: DETAILS OF E-105 PERFORMANCE. ......................................................................................................................... 103 FIGURE 75: COOLERS E-106, E-107, E-108, AND E-109 RESPECTIVELY. ..................................................................................... 105 FIGURE 76: DESIGN PARAMETERS OF E-106. ............................................................................................................................ 105 FIGURE 77: DESIGN PARAMETERS OF E-107. ............................................................................................................................. 105 FIGURE 78: DESIGN PARAMETERS OF E-108. ............................................................................................................................. 105 FIGURE 79: DESIGN PARAMETERS OF E-109. ............................................................................................................................. 106 FIGURE 80: FIRED HEATER H-101. ............................................................................................................................................ 107 FIGURE 81: CONDITIONS OF H-101. .......................................................................................................................................... 107 FIGURE 82: HEAT DUTY OF H-101. ........................................................................................................................................... 107 FIGURE 83: FIRED HEATER H-102. ............................................................................................................................................ 108 FIGURE 84: CONDITIONS OF H-102. .......................................................................................................................................... 108 FIGURE 85: HEAT DUTY OF H-102. ........................................................................................................................................... 108 FIGURE 86: FIRED HEATER H-103. ............................................................................................................................................ 109 FIGURE 87: CONDITIONS OF H-103. .......................................................................................................................................... 109 FIGURE 88: HEAT DUTY OF H-103. ........................................................................................................................................... 109 FIGURE 89: FIRED HEATER H-104. ............................................................................................................................................. 110

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FIGURE 90: CONDITIONS OF H-104. ........................................................................................................................................... 110 FIGURE 91: HEAT DUTY OF H-104. ............................................................................................................................................ 110 FIGURE 92: COMPRESSOR C-101 ............................................................................................................................................... 111 FIGURE 93: PARAMETERS OF C-101. .......................................................................................................................................... 111 FIGURE 94: C-101 CONDITIONS. ................................................................................................................................................ 111 FIGURE 95: COMPRESSORS C-102 & C-103. ............................................................................................................................... 112 FIGURE 96: PARAMETERS OF C-102. .......................................................................................................................................... 112 FIGURE 97: C-102 CONDITIONS. ................................................................................................................................................ 113 FIGURE 98: PARAMETERS OF C-103. .......................................................................................................................................... 113 FIGURE 99: C-103 CONDITIONS. ................................................................................................................................................ 113 FIGURE 100: PFR SCHEMATIC DIAGRAM. ................................................................................................................................... 116 FIGURE 101: ALGORITHMS OF REACTOR SIZING. ......................................................................................................................... 117 FIGURE 102: POLYMATH CODE. .................................................................................................................................................127 FIGURE 103: POLYMATH CODE. ................................................................................................................................................ 128 FIGURE 104: TEMPERATURE PROFILE OF THE REACTOR (K) VS VOLUME OF THE CATALYST (M3) ............................................. 129 FIGURE 105: FLOWRATES PROFILE (KMOL/S) VS VOLUME OF CATALYST (M3) .......................................................................... 130 FIGURE 106: SINGLE PASS CONVERSION OF PROPANE VS VOLUME OF THE CATALYST................................................................. 131 FIGURE 107: MAXIMUM ALLOWABLE STRESS VS TEMPERATURE FOR DIFFERENT GRADES ....................................................... 134 FIGURE 108: GILLILAND CORRELATION CURVE. ...................................................................................................................... 142 FIGURE 109: CORRESPONDED VALUE FOR (R-RMIN/R+1)...................................................................................................... 143 FIGURE 110: GILLILAND CORRELATION CURVE.........................................................................................................................153 FIGURE 111: CORRESPONDED VALUE FOR (R-RMIN/R+1). .......................................................................................................153 FIGURE 112: GILLILAND CORRELATION. .................................................................................................................................. 170 FIGURE 113: HEAT EXCHANGER OF A SHELL AND TUBE TYPE. ...................................................................................................176 FIGURE114 : CORRECTION FACTOR. ........................................................................................................................................179 FIGURE115 : FRICTION FACTOR JF. .......................................................................................................................................... 181 FIGURE 116: PITCH ARRANGEMENT. ........................................................................................................................................ 182 FIGURE117 : THE VALUES OF THE SHELL DIAMETER FOR DIFFERENT TYPE OF HEAT EXCHANGERS. ......................................... 183 FIGURE 118: FRICTION FACTOR JF. .......................................................................................................................................... 184 FIGURE 119: HEAT TRANSFER FACTOR JH. ............................................................................................................................... 185 FIGURE 120: FIRED HEATER. ................................................................................................................................................. 207 FIGURE 121: FLUE GAS TEMPERATURE. ...................................................................................................................................208 FIGURE 122: THE RELATION BETWEEN Α AND CTC/D0. ............................................................................................................ 209 FIGURE 123: ASSUMED FURNACE SHAPE. ................................................................................................................................ 210 FIGURE 124: GAS EMISSIVITY.................................................................................................................................................. 210 FIGURE 125: THE RELATION BETWEEN ΣQ/(Α ACP ) AND FRICTION FACTOR............................................................................. 211 FIGURE 126: THE TEMPERATURE AGAINST THE MAXIMUM ALLOWABLE STRESS FOR CARBON STEEL. ........................................... 221 FIGURE 127: THE TEMPERATURE AGAINST THE MAXIMUM ALLOWABLE STRESS FOR STAINLESS STEEL. ........................................ 222 FIGURE 128: PLANT LAYOUT. ................................................................................................................................................. 234 FIGURE 129: CASH FLOW DIAGRAM (DISCOUNTED).................................................................................................................... 243 FIGURE 130: CASH FLOW DIAGRAM (NON-DISCOUNTED). ........................................................................................................... 244 FIGURE 131: CUMULATIVE NUMBER OF DATA POINTS VS NET PRESENT VALUE. ........................................................................... 244 FIGURE 132: CUMULATIVE NUMBER OF DATA POINTS VS DCFROR. .......................................................................................... 245 FIGURE 133: CUMULATIVE NUMBER OF DATA POINTS VS CUMULATIVE CASH POSITION. .............................................................. 245 FIGURE 134: CUMULATIVE NUMBER OF DATA POINTS VS ROROI. .............................................................................................. 246 FIGURE 135: CUMULATIVE NUMBER OF DATA POINTS VS PAYBACK PERIOD. ............................................................................... 246 FIGURE 136: TEMPERATURE VS ENTHALPY FOR HOT AND COLD COMPOSITE CURVE. ................................................................... 247

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FIGURE 137: COST VS ∆TMIN. .................................................................................................................................................... 248 FIGURE 138: COMPOSITE CURVE............................................................................................................................................... 249

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Executive Summary This report illustrates the process of Propane Dehydrogenation (PDH). It is required to 400 KT/year of Propylene with purity of 99.5% and selectivity of Propylene not below 80%. In PDH process three main reactions are maintained and they are endothermic reactions. The main reaction is an equilibrium reaction of Propane to produce Propylene and Hydrogen. The side reactions are the reaction of Propane to produce Methane and Ethylene, and the reaction of Ethylene and Hydrogen to produce Ethane, where Platinum (Pt) is being used in PDH process as a catalyst.

In chapter one (Literature Review), alternative processes of producing Propylene and major differences between them are listed such as Propane Dehydrogenation, Methanol to Olefins, and Olefin Metathesis. Furthermore, properties of each material are being listed in this chapter.

Additionally, safety part and environment of the process has been mentioned and illustrated in this chapter such as operational safety, accidents response, and workers education. Finally, Bow-Tie diagrams of the toxicity, health risks, and flammability of the materials and National Fire Protection Association (NFPA) has been listed for each component.

In chapter two (Mass and Energy Balance), mass and energy balance calculation has been applied to all equipment in the system. These calculations were done based on the law of conservation of mass and energy by applying allowable assumptions.

In chapter three (Simulation), Aspen HYSYS V11 has been used to simulate the process of Propane Dehydrogenation (PDH). Process Flow Diagram (PFD) of PDH process has been mentioned in this chapter and detailed comparison between mass and energy balance calculations and Aspen HYSYS simulation has been listed with their percentage error difference for each equipment.

Additionally, three case studies have been applied to reactors which are the effect of changing temperature of the reactors on selectivity and conversion, the effect of changing pressure of the reactors on selectivity and conversion, and the effect of changing volume of the reactors on selectivity and conversion.

In chapter four (Equipment Design), detailed design of plug flow reactors (PFR), distillation columns, flash drum, heat exchangers, compressors, fired heaters, condensers, reboilers, and pippin have been shown in this chapter. It has been found that the volume of each reactor to be equal to 3.2072. Furthermore, Depropanizer has 24 stages, Deethanizer has 26 trays, and Propane/Propylene splitter has 145 trays. Finally, a plant layout of the PDH process has been listed at the end of this chapter.

In chapter five (Economics and Heat Integration), economic analysis of PDH process has been done on many aspects including capital cost, total bare module cost, grassroot costs, water operation cost, waste treatment cost, operating labor cost, utility cost, raw material cost, and fixed capital cost. For heat integration part, heat integration has been applied to the system to find if there are possibilities of reducing utilities. In this part (∆Tmin) has been assumed to be 10 oC

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Introduction Propane Dehydrogenation (PDH) is a process that describes the production of Propylene.

Propane Dehydrogenation is considered as an essential process, since the outcome of the process is ranked as the second biggest volume in petrochemical industries after Ethylene. Propylene production can be achieved by several ways including Propane Dehydrogenation, olefin metathesis, and Methanol to olefin (MTO) which starts by converting the natural gas to Methanol for further processing to produce the desired product Propylene. There are many valuable products that can be derived from Propylene such as Polypropylene.

Polypropylene is produced via polymerization of Propylene, and it has a large demand in the world market since it is characterized by high stiffness and high chemical resistance and implemented in packaging and manufacture of containers. Moreover, Propylene is considered as a byproduct of steam cracking process and fluid catalytic cracking (FCC) process hence, its value is largely dependent on the crude price.

The process of Propane Dehydrogenation is operated at mild pressure (0.5 – 3.5) bar, and high temperature (500 – 650) C introducing Platinum (Pt) or Chromium oxide (Cr O ) as a catalyst for the reaction. The reaction will produce the desired product which is Propylene and Hydrogen as a byproduct. Furthermore, it will carry two side reactions the first one will produce Methane and Ethylene, and the second is considered as a Hydrogenation reaction which will utilize the produced Ethylene and Hydrogen to produce Ethane.

2

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The principle of mass conservation which states that raw materials could be converted to any products but with same quantity is applied to construct an overall mass balance for the whole process and for each equipment. In addition, the first law of thermodynamics which states that energy is conserved is applied in order to construct an overall energy balance for all the process.

Simulation is an effective method to find all possible errors or any mishap in the process. It gives a general idea about each equipment elaborating the appropriate conditions. Aspen HYSYS is a convenient application that provides modeling of the process along with major stream and equipment data such as temperature and pressure, and more importantly help to obtain the mass and energy balance for all utilities. Aspen HYSYS gives us the advantage of comparing the obtained results with the individual calculation as classified in the literature. The utilized version of the application is Aspen V11.

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For the economy section, an overall study is performed following a strategy that under goes several steps. First, the CAPCOST was utilized to obtain the value of the capital cost, providing the bare module cost of all equipment. Secondly, the contingency, fee, and auxiliary facility costs were taken in account via the calculation of the total module and the grassroots costs. Moreover, the cost of manufacturing (MOC) was obtained by calculating operating labor, waste treatment, raw material, and the fixed capital investment cost. The costs were adjusted using 2022 chemical engineering plant cost index (CEPCI). Also, Heat integration is performed in order to maximize the process heat efficiency and minimize the costs through pinch analysis. The thermodynamics fundamentals applied to ensure the most profitable utilization of the heat of the process. Among any other methods, pinch analysis has been considered to be the best approach to accomplish heat integration.

In this project, the concentration will be on the production of Propylene via Propane Dehydrogenation. The plant’s target is to produce (0.4 – 0.455) million tons per year, considering selectivity above 80% and purity more than 99.5 %. Material and energy balance, simulation and economic scale studies are to be taken in account in order to guarantee a profitable plant.

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1

Literature Review

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Problem Statement The purpose of this report is to illustrate the importance of Propane Dehydrogenation process (PDH) in petrochemical industries. PDH process utilizes Propane in an endothermic reaction to produce polymer grade Propylene, which is the most used building block in Polypropylene synthesis.

Furthermore, it is expected to have a growth of 5% per year. The main source of Propane is from liquefied petroleum gas (LPG) which is rich in Propane, and contains both n-Butane, and isoButane. Initially, LPG stream is introduced to the Depropanizer unite in where the separation of Propane from the LPG stream occurs. The Depropanizer is mainly consist of distillation column, condenser and reboiler. The separated Propane is feed to PDH process in which a series of a catalytic reactors are used in order to produce Propylene as the main product, where Propane, Ethane, Ethylene, Methane, and Hydrogen are by-products. Reaction of PDH process is an endothermic and its formula is: 𝑘1

𝐶3 𝐻8 ←→ 𝐶3 𝐻6 + 𝐻2 𝑘−1

The side reactions are: 𝑘2

𝐶3 𝐻8 → 𝐶𝐻4 + 𝐶2 𝐻4 𝑘3

𝐶2 𝐻4 + 𝐻2 → 𝐶2 𝐻6

The recommended catalysts that can be utilized are Platinum (Pt) or Chromium oxide (Cr2O3) supported on alumina (Al2O3) at low pressure (0.5 - 3.5 bar) and at a high temperature (500 – 650 °C). It can be assumed that the reactor is operating at isobaric and adiabatic conditions. Moreover, the products stream is prepared for the separation of Propylene and Propane from the by-products in the Deethanizer unit. Deethanizer unit consists of distillation column, condenser, and reboiler similar to the Depropanizer. Both of Propylene and Propane from the bottom of the Deethanizer is sent to a splitter in which Propane is recycled, and Propylene is sent to the storage. Finally, the capacity of PDH process is estimated to be (400-455 KT/year) of Propylene with purity and selectivity above 99.5% and 80% respectively.

19

Figure 1: Block flow diagram (BFD) of Propane Dehydrogenation process.

Commercial Analysis, Production, and Technologies Used In recent years, the demand of Propylene outweighs the production, and the annual growth rate is expected to be 5%. Propylene is subsequent to Ethylene as the greatest volume petrochemical, and Propylene low production can be attributed to the fact that Propylene is produced as a byproduct from steam cracking around 50% and from FCC around 18% which makes refinery Propylene price dependent on the price of the crude. The same cannot be said to chemical and polymer grade Propylene prices which are behaving differently. To reduce the gap between the demand and the production, Propylene producers began to utilize on-purpose Propylene production which can be categorized into the following groups:

1. Propane Dehydrogenation.

2. Olefin metathesis.

3. Methanol to Olefin (MTO).

Resulting in rise of the number of PDH plants worldwide as shown in Figure 2.

20

Figure 2: World map showing PDH installations, plants in operation, and plants under construction.

According to the Japanese Ministry of Economy, trade, and industry (METI), the global production of Propylene in 2003 was approximately 60.2 million tons and the demand was 58.8 million tons. In 2009, a significant increase in the global demand and production was noticed to be 78.9 million tons for the demand and 76.2 million tons for the production as illustrated in Table 1.

Table 1: Propylene global supply and demand.

Year

2003

2009

Asian Total

Production Global

South

Western

North

Middle

Europe

America

East

& Demand

Total

Japan

Production

60.2

5.3

3.3

1.4

6.1

3.9

1.4

21.4

14.9

16.2

1.6

Demand

58.8

4.8

1.8

1.1

9.3

3.0

1.2

21.6

14.4

14.6

1.5

Balance

1.4

0.6

1.5

0.3

-3.2

0.9

0.2

-0.2

0.4

1.7

0

Production

76.2

5.8

3.3

1.7

9.4

4.6

2.4

27.3

16.1

18.3

5.8

Demand

78.9

5.5

2.2

1.4

15.3

4.1

2.1

31.2

17.0

18.4

2.9

Balance

-2.7

0.3

1.1

0.3

-5.9

0.5

0.3

-3.9

-1.0

-0.1

2.9

Korea

Taiwan China ASEAN India Total

21

in Saudi Arabia there are four plants that are dedicated to produce Propylene through means of Propane Dehydrogenation which are: 1.

2.

3.

4.

Al-Waha (using OLEFLEX-UOP).

National Petrochemical Industrial Co. (NATPET) (using OLEFLEX-UOP).

Saudi Polyolefin Co. (SPC) TASNEE (using CATOFIN-ABB).

Advanced Petrochemical Company (APC) (using CATOFIN-ABB).

Table 2 demonstrates the aforementioned companies with their technologies and Capacity per annum.

Table 2:Available PDH plants and their technologies in the Kingdom of Saudi Arabia.

PDH Plant (Technology)

Company Logo

Company Profile

Place

Capacity (KT/Year)

Al-Waha Petrochemical Co. has constructed Al-Waha

a Polypropylene plant based on Lyondell

(OLEFLEX)

Basell’s technology. Al-Waha was formed

Jubail

in 2006 as a joint between Sahara

450

Petrochemicals Company (75%) and Lyondell Basell (25%).

The National Petrochemical Industrial Co. NATPET (OLEFLEX)

(NATPET) has built a polypropylene plant which produces polypropylene product mix

Yanbu

420

of homopolymers, random and heterophasic copolymers for various applications.

SPC (CATOFIN)

Saudi Polyolefin Co. (SPC) has two integrated factories namely, propylene

Jubail

455

factory and polypropylene (PP) factory.

Advanced Petrochemical Company (APC) was established as a joint stock company in

APC

2005 to develop an integrated PDH and

(CATOFIN)

Polypropylene complex comprising an area

Jubail

455

of 650,000 m² and PP production of 450 KT/Year.

22

There are three main grades for Propylene which are: refinery, chemical, and polymer grades.

Each grade has its own market and customers. Most Propylene is produced as polymer grade Propylene for the making of Polypropylene which is the major derivative of Propylene.

Figure 3: propylene derivatives

Since the demand of plastic products had been increased in the last two decades, different technologies and processes had developed to fill the gap between the demand and the production.

One of these processes is Propane Dehydrogenation, which can be done using different technologies.

These technologies are listed in Table 3.

Table 3:Different technologies for Propane Dehydrogenation.

Reaction

Process

Licensor

Reactor type

Catalyst

CATOFIN

Lummus-Houdry

Fixed Bed

Cr2O3/Al2O3

Fluidized Bed

Cr2O3/Al2O3

Moving Bed

Pt/Al2O3

Fixed Bed

Cr2O3/Al2O3

590°C, > 1atm

Fixed Bed

Pt/Sn/Zn/Al2O3

500°C, 3.5atm

FBD-3

Oleflex

PDH STAR

SnamprogettiYarsintez UOP Linde-BASFStatoil Krupp Uhde

Conditions 560-620°C, >0.5atm 540-590°C, 1atm 550-650°C, >1atm

23

Alternative Processes and Raw Materials

Nowadays, different processes and raw materials can be used to produce Propene. One of them is called Methanol to Olefins Process (MTO). In this process, Methanol is used as raw material and dehydrated to form Dimethyl Ether (DME). Subsequently, the DME further reacts to form olefins such as Propene. Also, in the production of light alkenes, it is important to minimize the formation of aromatics, and this can be done using suitable zeolites. Moreover, the coke formation is an important factor in MTO process because it can deactivate the catalyst. Hence, frequent regeneration for the catalyst is required. In the MTO process, two fluidized bed reactors are used because the reaction is highly exothermic, and a good temperature control is required. Figure 4 shows a possible flow scheme for MTO process.

Figure 4: MTO process flow scheme.

24

Table 4: The product of UOP/Hydro MTO process in wt%.

Product (wt%)

MTO at 630 K and 2 bars

Light gases

2

Ethene

39

Propene

42

Butanes

12

C5+

5

Total

100

In Methanol to Olefins process, altering the reaction conditions result in a change in the Ethene to Propene ratio. Thus, MTO is considered to be a flexible process. Since the economic viewpoint of any process is important, some factors for MTO process need to be considered such as the local availability of natural gas, and the cost of natural gas and the transportation distance.

The metathesis of Olefin is an important organic reaction that was discovered in the World War II era. It is the conversion of Olefin to a different size Olefin. the mechanism involves the broken of the double bonds and the formation of new double bonds as illustrated in Figure 5.

Figure 5: Metathesis of alkenes; R1, R2, R3, R4 = H, CH3, CH2CH3, etc.

In the metathesis of Olefin to produce Propene, Ethene, and Butene. The reaction was discovered at Phillips Petroleum in the 1960’s, to convert propene the cheapest alkenes at the time into the valuable Butanes and Ethene. One of the industrial processes is the Olefins Conversion Technology (OCT) offered by ABB Lummus shown in Figure 6.

25

Figure 6:Typical flow scheme of the OCT metathesis process. Only one of multiple reactors is shown.

Reaction Kinetics, Catalyst, and Equilibrium The kinetics that are provided for Propane Dehydrogenation process are the following:

The main reaction: 𝑘1

𝐶3 𝐻8 ←→ 𝐶3 𝐻6 + 𝐻2 𝑘−1

The side reactions: 𝑘2

𝐶3 𝐻8 → 𝐶𝐻4 + 𝐶2 𝐻4 𝑘3

𝐶2 𝐻4 + 𝐻2 → 𝐶2 𝐻6 Rate of the main reaction: −𝑟1 = 𝑘1 (𝑃𝐶3 𝐻8 −

𝑃𝐶3 𝐻6 𝑃𝐻2 ) 𝐾𝑒𝑞

26

𝐾𝑒𝑞 = exp (20.5596 −

14.278 ) 𝑘𝑃𝑎 𝑇

Additionally, the rates of the side reactions: −𝑟2 = 𝑘2 𝑃𝐶3 𝐻8 −𝑟3 = 𝑘3 𝑃𝐶2 𝐻4 𝑃𝐻2

Kinetics parameters are as shown in Table 5: Table 5: Kinetics parameters.

Parameter

Value

Unit

k01 = 13.920

kmol/(kg.hr.kPa)

E1 = 31.978

kJ/mol

k02 = 1.573E6

kmol/(kg.hr.kPa)

E2 = 141.94

kJ/mol

k03 = 3.3965

kmol/(kg.hr.kPa2)

E3 = 149.41

kJ/mol

k1

k2

k3

Where, 𝐾𝐴 = 𝐾𝐴0 exp (−

𝐸𝐴 ) 𝑅𝑇

The catalyst used in Propane Dehydrogenation process is Platinum-Tin (Pt-Sn). This catalyst contains a noble metal on acidic support, which provides the active sites required for several reactions such as dehydrogenation and hydrocracking reactions. The acidic functions of the support must be minimized to prevent side reactions. Also, Platinum was found to have high activity towards paraffinic C─H bonds and low activity towards C─C cleavage. Furthermore, it has low attrition rates.

The catalyst life is estimated to be from 1-3 years, and it can endure high temperature. Moreover, the conversion is in a range of 35-40% with selectivity of 80-90%.

27

Process Flow Diagram (PFD)

Figure 7: Process flow diagram for Propane Dehydrogenation process (PDH).

28

Physical and Chemical Properties

Hydrogen is a colorless, tasteless, odorless, and non-metallic diatomic gas. Hydrogen occurs in three isotopes protium as the most abundant isotope and deuterium are stable isotopes, and radioactive isotope tritium is unstable. Moreover, it is the lightest element but most of the heavier compounds consist of hydrogen. Hydrogen classified as an extremely flammable, non-toxic, and non-corrosive gas. Hydrogen could be produced through many technologies, but the predominate ways are steam reforming, gasification, and water electrolysis. Physical and chemical properties of Hydrogen gas are shown in Table 6.

Figure 8: Hydrogen Ball and stick model.

Table 6: Physical and chemical properties of Hydrogen.

Chemical formula

H2

Molecular weight (g/mol)

2.02

Boiling temperature (C)

-252.76

Melting temperature (C)

-259

Heat of combustion (kJ/mol)

-285.8 (g)

Heat of vaporization (kJ/mol)

0.9

Heat of fusion (kJ/mol)

0.12

Critical pressure (atm)

12.79

Critical temperature (K)

33.3

29

Methane is a colorless, odorless gas, and belonging to the paraffin series. Furthermore, the gas is lighter than air and categorized as extremely flammable material. Moreover, it is the simplest form of hydrocarbon compounds which is the primary component of natural gas. Methane considered to be a greenhouse gas, and it has an impaction on the temperature and climate system of the earth. Also, methane classified as the second most abundant greenhouse gas after Carbon Dioxide.

Figure 9: Methane Ball and stick model.

Table 7: Physical and chemical properties of Methane.

Chemical formula

CH4

Molecular weight (g/mol)

16.04

Boiling temperature (C)

-161.5

Melting temperature (C)

-182.5

Heat of combustion (kJ/mol)

-890.36 (g)

Heat of vaporization (kJ/mol)

8.19

Heat of fusion (kJ/mol)

0.94

Critical pressure (atm)

45.8

Critical temperature (K)

190.7

30

Ethane is an odorless, colorless gas, and consist of single carbon-carbon bond. Also, the gas is lighter than air and categorized as extremely flammable material. In addition, it is the second simplest form of hydrocarbon compounds which is the secondary component of natural gas.

However, ethane occurs in petroleum oils and plays a major role in production of petrochemical industry, which has products of Ethanol, Ethane Diol, and Polyethylene.

Figure 10: Ethane Ball and stick model.

Table 8:Physical and chemical properties of Ethane.

Chemical formula

C2H6

Molecular weight (g/mol)

30.08

Boiling temperature (C)

-88.6

Melting temperature (C)

-183.3

Heat of combustion (kJ/mol)

-1559.9 (g)

Heat of vaporization (kJ/mol)

14.72

Heat of fusion (kJ/mol)

2.859

Critical pressure (atm)

48.2

Critical temperature (K)

305.4

31

Ethylene is an odor, colorless gas, and considered as the simplest olefins known as alkenes, which consist of double carbon-carbon bond. Also, the gas is lighter than air and categorized as extremely flammable material. However, ethylene could be obtained by heating one of the natural resources such as natural gas and petroleum. Moreover, Ethylene is a valuable industrial product due its multi-area uses, thus, ethylene use break into two main types, first as monomer which is used in polymerization reactions and produces Polyethylene. Second as raw material for the preparation of different two carbon compounds such as Ethanol, Ethylene Oxide, and Acetic Acid.

Figure 11: Ethylene Ball and stick model.

Table 9:Physical and chemical properties of Ethylene.

Chemical formula

C2H4

Molecular weight (g/mol)

28.05

Boiling temperature (C)

-103.7

Melting temperature (C)

-169.2

Heat of combustion (kJ/mol)

-1410.99

Heat of vaporization (kJ/mol)

13.54

Heat of fusion (kJ/mol)

3.35

Critical pressure (atm)

50.5

Critical temperature (K)

283.1

32

Propane is an odorless, colorless gas, and simply liquefied. Also, the gas is heavier than air and categorized as extremely flammable material. However, propane could be obtained from different sources such as liquefied petroleum gas (LPG), natural gas, light crude oil, and refinery gases. Furthermore, propane considered to be valuable raw material in petrochemicals industries, and it participates in the production of Propylene and Ethylene.

Figure 12: Propane Ball and stick model.

Table 10: Physical and chemical properties of Propane.

Chemical formula

C3H8

Molecular weight (g/mol)

44.09

Boiling temperature (C)

-42.07

Melting temperature (C)

-187.6

Heat of combustion (kJ/mol)

-2220 (g)

Heat of vaporization (kJ/mol)

18.77

Heat of fusion (kJ/mol)

3.52

Critical pressure (atm)

42

Critical temperature (K)

369.9

33

Figure 13:Iso-Butane Ball and stick model.

Table 11: Physical and chemical properties of iso-butane.

Chemical formula

C4H10

Molecular weight (g/mol)

58.12

Boiling temperature (C)

-11.73

Melting temperature (C)

-159.6

Heat of combustion (kJ/mol)

-2868.8 (g)

Heat of vaporization (kJ/mol)

21.292

Heat of fusion (kJ/mol)

4.54

Critical pressure (atm)

36

Critical temperature (K)

408.1

34

Propylene is an odorless, colorless, and the gas is heavier than air and categorized as extremely flammable material. However, propylene could be produced by decomposition of propane or as by products from hydrocarbons reactions. Also, the propylene is a major material in the production of petrochemicals products such as plastics, fibers, and textiles.

Figure 14: Propylene Ball and stick model.

Table 12: Physical and chemical properties of Propylene.

Chemical formula

C3H6

Molecular weight (g/mol)

42.08

Boiling temperature (C)

-47.7

Melting temperature (C)

-185.2

Heat of combustion (kJ/mol)

-2058.4 (g)

Heat of vaporization (kJ/mol)

18.42

Heat of fusion (kJ/mol)

3

Critical pressure (atm)

45.4

Critical temperature (K)

365.1

35

Both Butanes are odorless, colorless, and the gases are heavier than air and categorized as extremely flammable material. Butane has two isomers called normal and iso, normal butane occurs as a straight chain of carbon-carbon bond, in contrast, the branched butane form called Iso-Butane.

However, both isomers can be formed in natural sources such as natural gas and crude oil.

Figure 15: Butane Ball and stick model.

Table 13: Physical and chemical properties of butane.

Chemical formula

C4H10

Molecular weight (g/mol)

58.12

Boiling temperature (C)

-0.6

Melting temperature (C)

-138.3

Heat of combustion (kJ/mol)

-2878.5 (g)

Heat of vaporization (kJ/mol)

22.305

Heat of fusion (kJ/mol)

4.661

Critical pressure (atm)

37.47

Critical temperature (K)

425.17

36

Butylene known as butene are odorless, colorless, and the gases are heavier than air and categorized as extremely flammable material. Also, Butene has four isomeric compounds called 1Butene, cis-Butene, trans-Butene, and Iso-Butylene. However, Butylene could be produced through cracking process, dehydrogenation of butane, decomposition of hydrocarbons. Moreover, Butylene plays an important role in the production of gasoline.

Figure 16: 1- Butylene Ball and stick model.

Table 14: Physical and chemical properties of butylene.

Chemical formula

C4H8 1-Butene

Molecular weight (g/mol)

56.1

Boiling temperature (C)

-6.25

Melting temperature (C)

-185.3

Heat of combustion (kJ/mol)

-2718.6 (g)

Heat of vaporization (kJ/mol)

21.916

Heat of fusion (kJ/mol)

3.848

Critical pressure (atm)

39.7

Critical temperature (C)

419.6

37

Safety and Environment Information Safety is an essential part of any plant, and any accident or mishap could cost greatly.

Operation safety exist to ensure the workers safety and health, and to prevent any accidents. Another side of safety is how to handle accidents, emergency situations and learn to prevent it from happening again. This will be elaborated under three sections which are operational safety, accidents response, and workers education.

Operational Safety is a fundamental requirement for a successful plant. Operational Safety is a commitment to fully implement a specific set of Principles that warrants we operate in a safe, dependable, and environmentally well manner. Operational Safety is the foundation upon which we deliver the best products & services to our customers, while ensuring the safety of our employees, contractors operating with us, and the public. We will ensure a Safety stander with focus in all our operations by always committing to the following key Principles: 1.

2.

3.

4.

5.

6.

Hire the best people with the right skills.

Employ safe work procedures and behaviours.

Oversite commitment with all safety policies and procedures.

Ensure full compliance with guidelines regulations.

Encourage safe operational management of facilities, vehicles, and assets.

Make sure all safety equipment are in place and properly maintained.

1. Accidents can happen in any workplace, but it is more likely to happen in industrial work areas. The initial response is vital and must be understood by all workers, as it could make the difference. The following practices must be adhered and applied.

2. Control the accident area and organize.

3. Call the emergency group and perform first aid. Make sure someone else can direct help while performing first aid. Giving that each team consist of more than two workers this collaboration can easily be managed.

4. Keep the scene on lockdown to prevent another accident and allow only essential workers. For example, if there has been a spill, workers wandering around could cause another incident.

5. Take note of people and conditions at the scene. witnesses to what happened and injured subjects. Using a pad or at least looking around and mentally memorizing.

6. Save physical evidence securely. Surround the area with restricted area tape to control access.

38

Education and safety training are of a great importance to all workers as it grants them the right attitude and skills to work productively and safely. Another role is to give an insight to the safety program itself, so they can contribute, implement, and develop the program. Education will provide all workers with: 1.

2.

3.

4.

Knowledge on safe practices that will prevent hazards to people or workplace.

Awareness of plant hazards and dangerous areas to prevent accidents.

Special training for specific tools or operations.

Education and training can be given outside traditional classroom as peer to peer or seminars or location visits to educate effectively.

Figure 17: Bow-Tie Diagram of the risk assessment of the toxicity of the materials.

Figure 18:Bow-Tie Diagram of the risk assessment of the health risks of the materials.

39

Figure 19: Bow-Tie Diagram of the risk assessment of the flammability of the materials.

Table 15: NFPA of Hydrogen.

Diamond

Hazard

Value

Health

0

Flammability

4

Instability

0

Description No hazard beyond that of ordinary combustible material.

Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient temperature.

Normally stable, even under fire conditions.

Special

(NFPA, 2010)

Table 16: NFPA of Methane.

Diamond

Hazard Health

Value 2

Description Can cause temporary incapacitation or residual injury.

Burns readily. Rapidly or completely

Flammability

4

vaporizes at atmospheric pressure and normal ambient temperature.

Instability

0

Normally stable, even under fire conditions.

Special

(NFPA, 2010)

40

Table 17: NFPA of Ethane.

Diamond

Hazard Health

Value

Description

1

Can cause significant irritation.

Burns readily. Rapidly or completely

Flammability

4

vaporizes at atmospheric pressure and normal ambient temperature.

Instability

0

Normally stable, even under fire conditions.

Special

(NFPA, 2010)

Table 18: NFPA of Ethylene.

Diamond

Hazard

Value

Health

2

Description Can cause temporary incapacitation or residual injury.

Burns readily. Rapidly or completely

Flammability

4

vaporizes at atmospheric pressure and normal ambient temperature.

Readily undergoes violent chemical

Instability

2

changes at elevated temperatures and pressures.

Special

(NFPA, 2010)

41

Table 19: NFPA of Propane.

Diamond

Hazard

Value

Health

2

Description Can cause temporary incapacitation or residual injury.

Burns readily. Rapidly or completely

Flammability

4

vaporizes at atmospheric pressure and normal ambient temperature.

Instability

0

Normally stable, even under fire conditions.

Special

(NFPA, 2010)

Table 20: NFPA of Propylene.

Diamond

Hazard Health

Value

Description

1

Can cause significant irritation.

Burns readily. Rapidly or completely vaporizes at

Flammability

4

atmospheric pressure and normal ambient temperature.

Instability

1

Normally stable but can become unstable at elevated temperatures and pressures.

Special

(NFPA, 2010)

42

Table 21: NFPA of Butane.

Diamond

Hazard Health

Value

Description

1

Can cause significant irritation.

Burns readily. Rapidly or completely

Flammability

4

vaporizes at atmospheric pressure and normal ambient temperature.

Instability

Normally stable, even under fire

0

conditions.

Special

(NFPA, 2010)

Table 22: NFPA of Iso-Butane.

Diamond

Hazard Health

Value 0

Description No hazard beyond that of ordinary combustible material.

Burns readily. Rapidly or completely

Flammability

4

vaporizes at atmospheric pressure and normal ambient temperature.

Instability

0

Normally stable, even under fire conditions.

Special

(NFPA, 2010)

43

Table 23: NFPA of 1-Butene.

Diamond

Hazard Health

Value

Description

1

Can cause significant irritation.

Burns readily. Rapidly or completely

Flammability

4

vaporizes at atmospheric pressure and normal ambient temperature.

Instability

0

Normally stable, even under fire conditions.

Special

(NFPA, 2010)

Preliminary Cost of The Materials and Profit Margin Table 24: prices of chemical compounds.

Chemical

Molecular weight

Source of

component

(kg/mol)

chemical

Hydrogen

2.02

Methane

Price ($/MT)

Price ($/kmol)

PDH Process

3330

6.73

16.04

By product

250

4.01

Ethane

30.08

By product

258

7.76

Ethylene

28.05

By product

1014

28.44

Propane

44.09

Saudi Aramco

740

29.40

Propylene

42.08

PDH Process

1048

44.10

44

For the calculation of the range of the profit margin the three reactions were considered:

The main reaction is: 𝑘1

𝐶3 𝐻8 ←→ 𝐶3 𝐻6 + 𝐻2 𝑘−1

The side reactions are: 𝑘2

𝐶3 𝐻8 → 𝐶𝐻4 + 𝐶2 𝐻4 𝑘3

𝐶2 𝐻4 + 𝐻2 → 𝐶2 𝐻6 The following tables is constructed according to the stochiometric ratios.

Table 25: the upper limit of the profit margin using stoichiometry.

Chemical component

Consumption

Generation

Difference

Price

$ per 1 kmol of propylene

Hydrogen Methane Ethane Ethylene Propane Propylene

0 0 0 0 2 0

1 1 0 1 0 1

1 1 0 1 -2 1

6.73 4.01 0.00 28.44 -65.25 44.10

18.03

Table 26: the lower limit of the profit margin using stoichiometry.

Chemical component Hydrogen Methane Ethane Ethylene Propane Propylene

Consumption

Generation

Difference

Price

$ per 1 kmol of propylene

1 0 0 1 2 0

1 1 1 1 0 1

0 1 1 0 -2 1

0.00 4.01 7.76 0.00 -65.25 44.10

-9.38

Table 25 shows the upper limit where the best-case scenario for the profit margin has been considered, which is only accounting for the propylene production and ethylene production. On the other hand, Table 26 shows the lower limit where the worst-case scenario for the profit margin is considered, which accounts all three reactions. According to the above tables, it has been found that

45

Propylene production will be in the range of [-9.38 to 18.03] $ per 1 kmol of propylene. Based on the listed range the process of Propane Dehydrogenation (PDH) shows a high percentage of profitability.

References •

Monai, M., Gambino, M., Wannakao, S., & Weckhuysen, B. M. (2021). Propane to olefins tandem catalysis: a selective route towards light olefins production. Chemical Society Reviews.

•

Wolf, D., Dropka, N., Smejkal, Q., & Buyevskaya, O. (2001). Oxidative dehydrogenation of propane for propylene production—comparison of catalytic processes. Chemical engineering science, 56(2), 713-719.

•

Peters, T. A., Liron, O., Tschentscher, R., Sheintuch, M., & Bredesen, R. (2016). Investigation of Pd-based membranes in propane dehydrogenation (PDH) processes. Chemical Engineering Journal, 305, 191-200.

•

Liao, B., Lei, Z., Xu, Z., Zhou, R., & Duan, Z. (2001). New process for separating propylene and propane by extractive distillation with aqueous acetonitrile. Chemical Engineering Journal, 84(3), 581-586.

•

Maddah, H. A. (2018). A comparative study between propane dehydrogenation (PDH) technologies and plants in Saudi Arabia. American Academic Scientific Research Journal for Engineering, Technology, and Sciences, 45(1), 49-63.

•

NFPA diamond for each http://websites.umich.edu/~safeche/index.html

material,

retrieved

from

46

2

Mass & Energy Balance

47

Introduction In chemical engineering processes, both material and energy balance are considered to be an important part in order to design any plant. Material balance plays a big role in determining inputs and outputs of the process. Also, it helps to predict the desired products yield. The needed power to operate the plant is obtained by performing the energy balance. This section will show the calculation for both mass and energy balance to produce propylene via propane dehydrogenation process.

The fundamental equations for both material and energy balance will be stated below:

𝐴𝑐𝑐𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑜𝑛 = 𝐼𝑛 − 𝑂𝑢𝑡 + 𝐺𝑒𝑛𝑒𝑟𝑎𝑡𝑖𝑜𝑛 – 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛

The accumulation term is neglected since the process is assumed to be steady state. however, for the mass balance around the reactor, extent of reaction formula will be used:

𝑛𝑖 = 𝑛 𝑖𝑜 + ∑𝑣𝑖 𝜉𝑗

Applying the first law of thermodynamic is essential in order to perform energy balance calculation: ∆𝐻 + ∆𝐸𝑘 + ∆𝐸𝑃 = 𝑄 + 𝑊

Where, ∆H: Difference in enthalpy. ∆Ek: Difference in kinetic energy. ∆ Ep: Difference in potential energy.

Q: The heat transferred in or out the system.

W: The work done to system or by the system.

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In addition, both ∆Ep and ∆Ek will be neglected due to their small values compared to the difference in enthalpy which result in the following equation:

∆𝐻 = 𝑄 + 𝑊

For heat of formation, the following formula will be used: ̂𝑖 − ∑ 𝑛̇ 𝐻 ̂𝑖 ∆𝐻̇ = ∑ 𝑛̇ 𝐻 𝑜𝑢𝑡

𝑖𝑛

𝑇𝑓

Ĥ = ∆Ĥ°𝑓 (25𝑜𝐶, 1 𝑎𝑡𝑚) + ∫ 𝐶𝑃,𝑖 𝑑𝑇 𝑇𝑖

Cp is the heat capacity and can be calculated using the formula:

𝐶𝑝𝑖 = 𝐴𝑖 + 𝐵𝑖 𝑇 + 𝐶𝑖 𝑇 2 + 𝐷𝑖 𝑇 3 (𝐿𝑖𝑞𝑢𝑖𝑑)

𝐶𝑝𝑖 = 𝐴𝑖 + 𝐵𝑖 𝑇 + 𝐶𝑖 𝑇 2 + 𝐷𝑖 𝑇 3 (𝐺𝑎𝑠)

Also, 𝑇𝑓

∫ 𝐶𝑃,𝑖 𝑑𝑇 = [𝑎𝑇 + 𝑇𝑖

𝑏 2 𝑐 𝑇 𝑇 + 𝑇 3 ] 𝑇21 2 3

49

Calculations

Input and Output diagram with the chemical equations: 𝑘11

𝐶3 𝐻8 ←→ 𝐶3 𝐻6 + 𝐻2 (𝐷𝑒𝑠𝑖𝑟𝑒𝑑 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛) 𝑘−1

𝑘2

𝐶3 𝐻8 → 𝐶𝐻4 + 𝐶2 𝐻4 (𝑈𝑛𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛) 𝑘3

𝐶2 𝐻4 + 𝐻2 → 𝐶2 𝐻6 (𝑈𝑛𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛)

Figure 20: Block flow diagram of PDH process.

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Assumptions: -

Adiabatic Reactor.

Conversion 40%.

Selectivity given is 80% of propane to propylene.

Heterogeneous reaction.

Ethylene consumption is 20% of Ethylene Produced.

Basis 100 Kmol of pure propane.

Block Flow Diagram (BFD) for The Reactor

Inlet FC3H8

PDH Reactor

Outlet FH2 FCH4 FC2H6 FC2H4 FC3H8 FC3H6

Figure 21: PDH reactor

𝐹𝐶3 𝐻8 = 𝐹𝐶3 𝐻8 − 𝜉1 − 𝜉2 0

𝐹𝐶3 𝐻6 = 𝐹𝐶3 𝐻6 + 𝜉1 0

𝐹𝐶2 𝐻4 = 𝐹𝐶2 𝐻4 0 + 𝜉2 − 𝜉3

𝐹𝐶2 𝐻6 = 𝐹𝐶2 𝐻6 + 𝜉3 0

𝐹𝐶𝐻4 = 𝐹𝐶𝐻4 0 + 𝜉2

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𝐹𝐻2 = 𝐹𝐻2 0 + 𝜉1 − 𝜉3

𝑥= 𝑆𝑝 =

𝐹0 − 𝐹 100 − 𝐹 = 0.4 = , 𝐹 = 100(1 − 0.4) = 60 𝐾𝑚𝑜𝑙 𝐹0 100

𝐹𝐷 /𝜐𝐷 𝐹𝐷 = 0.8 = , 𝐹 = 0.8(100 − 60) = 32 𝐾𝑚𝑜𝑙 (𝐹𝐴0 − 𝐹𝐴 )/|𝜐𝐴 | (100 − 60) 𝐷

Material Balance for Propylene 𝐹𝐶3 𝐻6 = 𝐹𝐶3 𝐻6 + 𝜉1 0

32 = 0 + 𝜉1 𝜉1 = 32 𝐾𝑚𝑜𝑙𝑒

Material Balance for Propane 𝐹𝐶3 𝐻8 = 𝐹𝐶3 𝐻8 − 𝜉1 − 𝜉2 0

60 = 100 − 32 − 𝜉2 𝜉2 = 8 𝐾𝑚𝑜𝑙𝑒

Material Balance for Ethylene 𝐹𝐶2 𝐻4 = 𝐹𝐶2 𝐻4 0 + 𝜉2 − 𝜉3 Assuming 20% of Ethylene is consumed:

6.4 = 0 + 8 − 𝜉3 𝜉3 = 1.6 𝐾𝑚𝑜𝑙𝑒

Material Balance for Hydrogen 𝐹𝐻2 = 𝐹𝐻2 0 + 𝜉1 − 𝜉3 𝐹𝐻2 = 0 + 32 − 1.6 𝐹𝐻2 = 30.4 𝐾𝑚𝑜𝑙𝑒

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Material Balance for Methane 𝐹𝐶𝐻4 = 𝐹𝐶𝐻4 0 + 𝜉2 𝐹𝐶𝐻4 = 0 + 8 𝐹𝐶𝐻4 = 8 𝐾𝑚𝑜𝑙𝑒

Material Balance for Ethane 𝐹𝐶2 𝐻6 = 𝐹𝐶2 𝐻6 + 𝜉3 0

𝐹𝐶2 𝐻6 = 0 + 1.6 𝐹𝐶2 𝐻6 = 1.6 𝐾𝑚𝑜𝑙𝑒

Total Outlet of the Reactor 𝐹𝑇𝑜𝑡𝑎𝑙 𝑖𝑛 = 𝐹𝐶3 𝐻8 + 𝐹𝐶3 𝐻6 + 𝐹𝐶2 𝐻4 0 + 𝐹𝐶2 𝐻6 + 𝐹𝐶𝐻4 0 + 𝐹𝐻2 0 0

0

0

𝐹𝑇𝑜𝑡𝑎𝑙 = 𝐹𝐶3 𝐻8 + 𝐹𝐶3 𝐻6 + 𝐹𝐶2 𝐻4 + 𝐹𝐶2 𝐻6 + 𝐹𝐶𝐻4 + 𝐹𝐻2 𝐹𝑇𝑜𝑡𝑎𝑙 𝑖𝑛 = 100 + 0 + 0 + 0 + 0 + 0 = 100 𝐾𝑚𝑜𝑙 𝐹𝑇𝑜𝑡𝑎𝑙 = 60 + 36 + 6.4 + 1.6 + 8 + 30.4 = 138.4 𝐾𝑚𝑜𝑙

Mole Fractions of The Reactor Outlet

𝑦𝐶3 𝐻8 =

60 = 0.43 138.4

𝑦𝐶3 𝐻6 =

36 = 0.23 138.4

𝑦𝐶2 𝐻4 =

6.4 = 0.04 138.4

𝑦𝐶2 𝐻6 =

1.6 = 0.01 138.4

𝑦𝐶𝐻4 =

8 = 0.06 138.4

𝑦𝐻2 =

30.4 = 0.22 138.4

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Table 27: Heat of formation of each component at standard conditions.

Compound

Propane

Propylene

ethylene

ethane

methane

hydrogen

∆Ĥ°f (kJ/mol)

-103.8

20.41

52.28

-84.67

-74.85

0

𝑇𝑓

∫ 𝐶𝑃,𝑖 𝑑𝑇 𝑇𝑖

Cp,i = Ai + BiT + CiT2 +DiT3

Table 28: Coefficients used to calculate heat capacity.

Compound

a*10^3

b*10^5

c*10^8

d*10^12

Propane

68.03

22.59

-13.11

31.71

Propylene

59.58

17.71

-10.17

24.60

Ethylene

40.75

11.47

-6.89

17.66

Ethane

49.37

13.92

-5.82

7.28

Methane

34.31

5.47

0.37

-11.00

Hydrogen

28.84

0.01

0.33

-0.87

𝑇

∆Ĥ = ∆Ĥ°f (25oC, 1 atm) + ∫𝑇 𝑓 𝐶𝑃,𝑖 𝑑𝑇 𝑖

Table 29: Table 29: Change in heat at reactor conditions.

Compound

Propane

Propylene

Ethylene

Ethane

Methane

Hydrogen

∆Ĥ (kJ/Mol)

-24.21

86.79

96.42

-29.45

-42.03

18.30

̂ = ∑ 𝑛𝑖 𝐻 ̂𝑖 − ∑ 𝑛𝑖 𝐻 ̂𝑖 ∆𝐻 𝑜𝑢𝑡

𝑖𝑛

̂ = (60 × −24.21 + 32 × 86.79 + 6.4 × 96.42 + 1.6 × −29.45 + 8 × −42.03 + 30.4 × 18.30) ∆𝐻 − (100 × −24.21) = 4536129.60 𝑘𝐽/𝑘𝑚𝑜𝑙

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Assumptions: -

Constant Molal Overflow (CMO).

-

Basis 100 kmol of LPG (65% propane, 17.5 n-butane, 17.5 iso-butane).

-

Propane mole fraction in the distillate is 99.5% from the feed.

-

Reflux ratio 1.7.

Overall Mass Balance 𝐹 =𝐵+𝐷

100 = B + D Calculation based on Most volatile component: 𝑧𝐹 = 𝑋𝐵 𝐵 + 𝑋𝐷 𝐷 0.65*100=0.005*B+0.995*D D=64.5/0.99= 65.15 Kmol B=100–65.15=34.85 Kmol

L0= D * L0/D L0= 65.15*1.7= 110.76 Kmol

V1=D+L0.

V1=65.15+110.76=175.91 Kmol

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Overall Energy Balance FhF + Qc + Qr= DhD + BhB. Energy balance around the condenser:

V1H1+Qc=DhD+L0h0 Qc=V1(hD-H1) =V1(-λ)

𝜆 = 24787 𝑘𝐽/𝐾𝑚𝑜𝑙𝑒

𝑄𝑐 = 24787 ∗ 175.91 = − 4360258 𝑘𝐽/ℎ

Qr= DhD + BhB - FhF - Qc 47

47

47

ℎ𝐹 = ∫ 𝐶𝑝−𝑝𝑟𝑜𝑝𝑎𝑛𝑒 𝑑𝑇 + ∫ 𝐶𝑝−𝑏𝑢𝑡𝑎𝑛𝑒 𝑑𝑇 + ∫ 𝐶𝑝−𝑖𝑠𝑜𝑏𝑢𝑡𝑎𝑛𝑒 𝑑𝑇 = 177783 25

25

25

44

ℎ𝐷 = ∫ 𝐶𝑝 𝑑𝑇 = 136002 25

98.5

ℎ𝐵 = ∫ 25

𝑘𝐽 𝐾𝑚𝑜𝑙𝑒

98.5

𝐶𝑝−𝑏𝑢𝑡𝑎𝑛𝑒 𝑑𝑇 + ∫ 25

𝑘𝐽 𝐾𝑚𝑜𝑙𝑒

𝐶𝑝−𝑖𝑠𝑜𝑏𝑢𝑡𝑎𝑛𝑒 𝑑𝑇 = 15886.47

𝑘𝐽 𝐾𝑚𝑜𝑙𝑒

Qr = 65.15*136002+34.85*15886.47 - 100*177783+4360258=11996631.78 kJ/hr

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Assumptions: -

Constant Molal Overflow (CMO).

Basis 100 Kmol.

Propane recovery in the bottom is 99.5% of the feed.

Reflux ratio 1.7.

All Light non-keys are recovered in the distillate.

All heavy non-keys are recovered in the bottom.

Overall Mass Balance F=B+ D 100 = 𝐵 + 𝐷

Table 30: Inlet compositions to T-102.

C3H8

0.44

C3H6

0.23

C2H4

0.04

C2H6

0.01

CH4

0.06

H2

0.22

Distillate calculation:

DxC2H4= zC2H4 F = 4 Kmol/hr. 𝐷𝑥𝐶2 𝐻6 = 𝑧𝐶2 𝐻6 𝐹 = 0.995 ∗ 0.01 ∗ 100 = 0.995 𝐾𝑚𝑜𝑙/ℎ𝑟.

DxCH4= zCH4 F = 6 Kmol/hr.

𝐷𝑥𝐻2 = 𝑧𝐻2 𝐹 = 22 𝐾𝑚𝑜𝑙/ℎ𝑟.

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𝐷𝑥𝐶3 𝐻6 = 𝑧𝐶3 𝐻6 𝐹 = (1 − 0.995) (0.23) (100) = 0.115 𝐾𝑚𝑜𝑙/ℎ𝑟.

𝑇𝑜𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑖𝑙𝑙𝑎𝑡𝑒 = 33.11 𝐾𝑚𝑜𝑙/ℎ𝑟

Table 31: Mole fractions of the distillate.

C3H8

0.66

C3H6

0.34

C2H4

0

C2H6

7.47E-5

CH4

0

H2

0

Bottom calculation: Total bottom = F - D=100-33.11= 66.89 kmol/hr 𝐵𝑥𝐶3 𝐻8 = 𝑧𝐶3 𝐻8 𝐹 = 44 𝑘𝑚𝑜𝑙/ℎ𝑟

𝐷𝑥𝐶3𝐻6 = 𝑧𝐶3𝐻6 𝐹 = 0.995 ∗ 0.23 ∗ 100 = 22.89 𝑘𝑚𝑜𝑙/ℎ𝑟

Table 32: Mole fraction of the bottom.

C3H8

0

C3H6

0.003

C2H4

0.12

C2H6

0.03

CH4

0.18

H2

0.664

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Overall Energy Balance FhF + Qc + Qr = DhD + BhB

Energy balance around the condenser: 𝑉1 𝐻1 + 𝑄𝑐 = 𝐷ℎ𝐷 + 𝐿0 ℎ0

𝑦1 = 𝑥𝐷 = 𝑥0

𝑄𝑐 = 𝑉1 (ℎ𝐷 − 𝐻1 ) = 𝑉1 (−𝜆)

Component

Vapor Mole Flow (kmol/hr)

∆Ĥvap (kJ/kmol)

∆Ĥ (kJ/hr)

CH4

15.49

8724

135157.44

H2

57.15

913

52178.39

C2H4

10.33

15936

164593.38

C2H6

2.58

17879

46165.37

C3H6

0.26

24787

6400.25

Total

85.81

404494.83

𝑄𝑐 = 404494.83 𝑘𝐽/ℎ. 𝑄𝑟 = 𝐷ℎ𝐷 + 𝐵ℎ𝐵 − 𝐹ℎ𝐹 − 𝑄𝑐 ℎ𝐹 = 845.45 𝑘𝐽/𝐾𝑚𝑜𝑙 ℎ𝐷 = −8493.63 𝑘𝐽/𝐾𝑚𝑜𝑙 ℎ𝐵 = −9943.65 𝑘𝐽/𝐾𝑚𝑜𝑙 𝑄𝑟 = 33.11 ∗ −8493.63 + 66.89 ∗ 9943.65 − 100 ∗ 845.45 + (404494.83) = 126624.33 𝑘𝐽/𝐾𝑚𝑜𝑙

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The Flash drum will be utilized to remove the hydrogen from the reactor effluent, hydrogen is very and complicated to cool it require a very low temperature to be liquified so it is better to remove early on before entering the distillation column.

The reactor effluent is containing: 1.

2.

3.

4.

5.

Propane.

Propylene.

Ethylene.

Methane.

Hydrogen.

Figure 22: Illustration of the flash drum.

The operating conditions 5 °C and 65 bar and operating adiabatically.

To find the compositions of the component in the vapor and liquid phase Rachford-Rice equation for multicomponent system must be applied. The values of K are obtained from Aspen HYSYS since this mixture is far from ideal. 𝑐

𝑉 (𝐾𝑖 − 1)𝑧𝑖 𝑓( ) = ∑ =0 𝑉 𝐹 (𝐾 1 + − 1) ( ) 𝑖=1 𝑖 𝐹 To solve the above equation, excel tool goal seek was used the following values were used in order to solve it.

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Table 33: Mole fraction and K-values of the system components.

Components

Comp

K-values

Propane

0.43

0.1339

Propylene

0.23

0.1688

Ethylene

0.04

0.6859

Ethane

0.01

0.76

Methane

0.06

2.458

Hydrogen

0.22

15.12

Using the above values V/F was calculated to be 0.2557.

Overall Mass Balance 𝐹𝑒𝑒𝑑 = 𝑉𝑎𝑝𝑜𝑟 + 𝐿𝑖𝑞𝑢𝑖𝑑 𝑉𝑎𝑝𝑜𝑟 = 𝐹𝑒𝑒𝑑 ∗

𝑉 = 4330 ∗ 0.2557 = 1107.229 𝑘𝑚𝑜𝑙/ℎ. 𝐹

𝐿𝑖𝑞𝑢𝑖𝑑 = 𝐹𝑒𝑒𝑑 − 𝑉𝑎𝑝𝑜𝑟 = 4330 − 1107.229 = 3222.771 𝑘𝑚𝑜𝑙/ℎ.

Table 34:Mole fraction of the components of the system.

components Propane Propylene Ethylene Ethane Methane Hydrogen

Liquid 0.552 0.292 0.043 0.011 0.044 0.048

Vapor 0.074 0.049 0.030 0.008 0.107 0.721

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Assumption: -

Constant Molal Overflow (CMO).

Basis 100 Kmol mixture of propane 65% and propylene 35%.

Propylene mole fraction in the distillate is 99.5% from the feed.

Reflux ratio 2.5.

Overall Mass Balance 𝐹 =𝐵+𝐷

100 = 𝐵 + 𝐷

Calculation based on Most volatile component:

𝑧𝐹 = 𝑥𝐵 𝐵 + 𝑥𝐷 𝐷 0.35 ∗ 100 = 0.005 ∗ 𝐵 + 0.995 ∗ 𝐷 𝐷 = 34.5/0.99 = 34.85 𝐾𝑚𝑜𝑙 𝐵 = 100– 65.15 = 65.15 𝐾𝑚𝑜𝑙 𝐿0 = 𝐷 ∗

𝐿0 𝐷

𝐿0 = 34.85 ∗ 2.5 = 87.12 𝐾𝑚𝑜𝑙 𝑉1 = 𝐷 + 𝐿0 𝑉1 = 87.12 + 34.85 = 121.97 𝐾𝑚𝑜𝑙

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Overall Energy Balance 𝐹ℎ𝐹 + 𝑄𝑐 + 𝑄𝑟 = 𝐷ℎ𝐷 + 𝐵ℎ𝐵

Energy balance around the condenser:

𝑉1 𝐻1 + 𝑄𝑐 = 𝐷ℎ𝐷 + 𝐿0 ℎ0 𝑄𝑐 = 𝑉1 (ℎ𝐷 − 𝐻1 ) = 𝑉1 (−𝜆) 𝜆 = 23177 𝑘𝐽/𝐾𝑚𝑜𝑙 𝑄𝑐 = 23177 ∗ 121.97 = − 2826891.7 𝑘𝐽/ℎ 𝑄𝑟 = 𝐷ℎ𝐷 + 𝐵ℎ𝐵 − 𝐹ℎ𝐹 − 𝑄𝑐.

47.8

ℎ𝐹 = 0.65 ∗ ∫

47.8

𝐶𝑝−𝑝𝑟𝑜𝑝𝑎𝑛𝑒 𝑑𝑇 + 0.35 ∗ ∫

25

𝐶𝑝−𝑝𝑟𝑜𝑝𝑦𝑙𝑒𝑛𝑒 𝑑𝑇 = 165325

25 44

44

ℎ𝐷 = 0.995 ∗ ∫ 𝐶𝑝−𝑝𝑟𝑜𝑝𝑦𝑙𝑒𝑛𝑒 𝑑𝑇 + 0.005 ∗ ∫ 𝐶𝑝−𝑝𝑟𝑜𝑝𝑎𝑛𝑒 𝑑𝑇 = 124673 25

25

55.97

ℎ𝐵 = 0.995 ∫ 25

𝑘𝐽 𝐾𝑚𝑜𝑙𝑒

55.97

𝐶𝑝−𝑝𝑟𝑜𝑝𝑎𝑛𝑒 𝑑𝑇 + 0.005 ∫ 25

𝑘𝐽 𝐾𝑚𝑜𝑙

𝐶𝑝−𝑝𝑟𝑜𝑝𝑦𝑙𝑒𝑛𝑒 𝑑𝑇 = 238168

𝑘𝐽 𝐾𝑚𝑜𝑙

𝑄𝑟 = 34.85 ∗ 124673 + 65.15 ∗ 238168 − 100 ∗ 165325 + 2826891.7 = 6155997.73 𝑘𝐽/ℎ

63

Figure 23: PFD of the compressors

For compressors the mass balance is simply in equals out. Moreover, the compressor is needed to compress the reactor effluents to reach the appropriate vessel pressure which is around 65 bars. In order to do that, three compressors and two intercoolers are required: Assumptions: -

Compression efficiency equal to 0.75. γ=Cp/Cv= (this value is taken from HYSYS). 𝛾

𝛾−1 𝛾 𝑃 𝑅 𝑇𝑖𝑛 ∗ 𝛾 − 1 ∗ ([ 𝑃𝑜𝑢𝑡 ] − 1) 𝑖𝑛 𝑊=𝑛 𝜀

Work Calculation for C-101

𝑊 = 100

𝐾𝑚𝑜𝑙 1ℎ ∗ ℎ 3600𝑠 8.314 𝐾𝐽 1.152 11.306 ( ∗ 𝐾 ) ∗ (333.84𝐾) ∗ ( ) ∗ ([ 2.96 ] 𝐾𝑚𝑜𝑙 1.152 − 1 ∗ 0.75

1.152−1 1.152

− 1)

W = 150.695 𝑘𝑊

𝛾

1 𝑃𝑜𝑢𝑡 𝛾−1 𝑇𝑜𝑢𝑡 = 𝑇𝑖𝑛(1 + ([ ] − 1)) 𝜀 𝑃𝑖𝑛

64

1 11.306 𝑇𝑜𝑢𝑡 = 333.84(1 + ([ ] 0.75 2.96

1.152−1 1.152

− 1))

𝑇𝑜𝑢𝑡 = 419.936 𝐾 = 146.9 𝐶

Table 35: Work and Tout for the compressors.

Compressor

Work (kW)

Tout oC

C-102

52.4302

75

C-103

138.853

119

65

Figure 24: PFD of the heat exchangers

The effluent of the last reactor which is a hot stream will be introduced to four heat exchangers to be cooled down and heat up the other fluid. However, it is known that the heat lost by the hot stream is equal to the heat gained by the cold stream.

𝑄 = ∆𝐻 𝑇

𝑄 = 𝑛 ∗ ∫ 𝐶𝑝 𝑑𝑇 25

𝑇𝑓

𝑇𝑓

∫ 𝐶𝑃,𝑝𝑟𝑜𝑝𝑎𝑛𝑒 𝑑𝑇(𝐶𝑜𝑙𝑑) = ∫ 𝐶𝑃,𝑚𝑖𝑥 𝑑𝑇 (𝐻𝑜𝑡) 𝑇𝑖

𝑇𝑖

Assumptions: -

Steady state process.

No shaft work.

No loss of energy due to fraction.

The effluent temperature assumed to be 550 C. Basis 100 kmol/h .

66

Energy Balance for Heat Exchanger (E-105)(Cooling Side) Calculating heat for each component: 192.7

QMethane = (0.0580*100) ∫354 34. 31 ∗ 10 − 3 + 5.469 ∗ 10 − 5𝑇 + 0.3661 ∗ 10 − 8𝑇^2 − 11 ∗ 10 − 12𝑇^3𝑑𝑇 = −46119.1

𝑘𝑗 ℎ

192.7

QEthane = (0.0145*100) ∫354 49.37 ∗ 10 − 3 + 13.92 ∗ 10 − 5𝑇 − 5.816 ∗ 10 − 8𝑇 2 + 7.28 ∗ 10 − 12𝑇^3𝑑𝑇 = −19438.2

𝑘𝑗 ℎ

192.7

QPropane = (0.4348*100) ∫354 68.032 ∗ 10 − 3 + 22.59 ∗ 10 − 5𝑇 − 13.11 ∗ 10 − 8𝑇 2 + 31.71 ∗ 10 − 12𝑇^3𝑑𝑇 = −844445

𝑘𝑗 ℎ

192.7

QPropene = (0.2318*100) ∫354 59.58 ∗ 10 − 3 + 17.71 ∗ 10 − 5𝑇 − 10.17 ∗ 10 − 8𝑇 2 + 24.6 ∗ 10 − 12𝑇^3𝑑𝑇 = −376574

𝑘𝑗 ℎ

192.7

QEthylene = (0.0435*100) ∫354 40.75 ∗ 10 − 3 + 11.47 ∗ 10 − 5𝑇 − 6.891 ∗ 10 − 8𝑇 2 + 17.66 ∗ 10 − 12𝑇^3𝑑𝑇 = −47149.1

𝑘𝑗 ℎ

192.7

QHydrogen = (0.2174*100) ∫354 28.84 ∗ 10 − 3 + 0.00765 ∗ 10 − 5𝑇 + 0.3288 ∗ 10 − 8𝑇 2 − 0.8698 ∗ 10 − 12𝑇^3𝑑𝑇 = −102024

𝑘𝑗 ℎ

𝑄𝑙𝑜𝑠𝑠 = ∑ Qmethane + QEthane + QPropane + QPropene + QEthylene+ QHydrogen = −46119.1 − 19438.2 − 844445 − 376574 − 47149.1 − 102024 = −1.4357 ∗ 106 kJ/h

Table 36: Heat exchangers and their duties.

Heat exchanger

Heat transfer (kJ/h)

E-106

−1.017 ∗ 106

E-105

−9.19 ∗ 105

E-104

−8.07 ∗ 105

E-101

−2.18 ∗ 105

67

Figure 25: PFD of the coolers

In order to provide the vessel with a proper stream temperature, four coolers were introduced. Moreover, two coolers were placed before and after the compressors with two inter stage coolers between two compressors are used.

Assumptions: -

Steady state process.

No shaft work.

No loss of energy due to fraction.

Basis 100 kmol/h

60.84

QMethane = (0.0580*100) ∫120 34. 31 ∗ 10−3 + 5.469 ∗ 10−5 𝑇 + 0.3661 ∗ 10−8 𝑇 2 − 11 ∗ 10−12 𝑇 3 𝑑𝑇 = −363361

𝑘𝐽 ℎ

60.84

QEthane = (0.0145*100) ∫120 49.37 ∗ 10−3 + 13.92 ∗ 10−5 𝑇 − 5.816 ∗ 10−8 𝑇 2 + 7.28 ∗ 10−12 𝑇 3 𝑑𝑇 = −5273.51

𝑘𝐽 ℎ

60.84

QPropane = (0.4348*100) ∫120 68.032 ∗ 10−3 + 22.59 ∗ 10−5 𝑇 − 13.11 ∗ 10−8 𝑇 2 + 31.71 ∗ 10−12 𝑇 3 𝑑𝑇 = −224749

𝑘𝐽 ℎ

−3 −5 −8 2 −12 3 60.84 QPropene = (0.2318*100) ∫120 59.58 ∗ 10 + 17.71 ∗ 10 𝑇 − 10.17 ∗ 10 𝑇 + 24.6 ∗ 10 𝑇 𝑑𝑇

= −102510

𝑘𝐽 ℎ

60.84

QEthylene = (0.0435*100) ∫120 40.75 ∗ 10−3 + 11.47 ∗ 10−5 𝑇 − 6.891 ∗ 10−8 𝑇 2 + 17.66 ∗ 10−12 𝑇 3 𝑑𝑇 = −19237.2

𝑘𝐽 ℎ

68

60.84

QHydrogen = (0.2174*100) ∫120 28.84 ∗ 10−3 + 0.00765 ∗ 10−5 𝑇 + 0.3288 ∗ 10−8 𝑇 2 − 0.8698 ∗ 10−12 𝑇 3 𝑑𝑇 = −37136

𝑘𝐽 ℎ

𝑄𝑙𝑜𝑠𝑠 = ∑ Qmethane + QEthane + QPropane + QPropene + QEthylene+ QHydrogen = − 3.88 ∗ 105 kJ/h

Table 37: Heat exchangers and their duties.

Heat exchanger

Heat transfer (kJ/h)

E-109

−4.13 ∗ 105

E-110

−3.85 ∗ 105

E-111

−9.26 ∗ 105

Fired heaters are used for reactions which required significant temperature and to maintain the reaction temperature in the reactors.

Assumption: -

Steady state process.

Fractional force is negligible.

No shaft work.

Both kinetic and potential energies are neglected. 𝑄 = ∆𝐻

𝑇

𝑄 = 𝑛 ∗ ∫ 𝐶𝑝 𝑑𝑇 25

650

𝑄 = 𝑛𝑃 ∗ ∫ 200

𝐶𝑃−𝑃𝑟𝑜𝑝𝑎𝑛𝑒 𝑑𝑇 = 100

𝐾𝑚𝑜𝑙𝑒 𝐾𝑗 𝐾𝑗 ∗ 63568.7 = 6356870 ℎ 𝐾𝑚𝑜𝑙𝑒 ℎ

69

Table 38: Heat calculation for heaters.

Fired heater name

Q (kJ/h)

H-102

4546330

H-103

4546330

H-104

4546330

Figure 26: PFD of the pump

The pumps are used to transfer a constants volume to a certain location in the plant.

Assumptions: -

The efficiency is 75% Adiabatic pump.

The work done can be calculated using the following equation: Ẇ =

𝑄̇​̇𝛥𝑝 𝜀

Where: 𝜀 = 0.75, Pin = 2000000 Pa, Pout = 2500000 Pa, Q̇= 104.28 m3/hr.

Ẇ =

104.28

𝑚3 × (2500000 − 2000000)Pa hr 0.75

Ẇ = 69.52 ∗ 106

𝐽 = 19.3 𝑘𝑊 ℎ𝑟

70

Table 39: Stream Specifications.

Stream Number

1

2

3

4

5

6

7

8

9

Temperature (°C)

50

50

90

89.9

50

35

80

120

180

Pressure (Bar)

6

6

6

15.17

15.17

3

3

3

3

Component composition Propane

0.65

0.825

0.825

0.04

0.9975

0.9975

0.9975

0.9975

0.9975

Propylene

0

0

0

0

0

0

0

0

0

n-Butane

0.175

0.087 5

0.0875

0.48

0.00032 0.00032 0.00032 0.00032

0.00032

Iso-Butane

0.175

0.087 5

0.0875

0.48

0.0021

0.0021

0.0021

0.0021

0.0021

Ethylene

0

0

0

0

0

0

0

0

0

Ethane

0

0

0

0

0

0

0

0

0

Methane

0

0

0

0

0

0

0

0

0

Hydrogen

0

0

0

0

0

0

0

0

0

Stream Number

10

11

12

13

14

15

16

17

18

Temperature (°C)

230

550

450

350

250

150

120

60.84

146.9

Pressure (Bar)

3

3

3

3

3

3

3

3

11.306

Component composition Propane

1

0.44

0.44

0.44

0.44

0.44

0.44

0.44

0.44

Propylene

0

0.23

0.23

0.23

0.23

0.23

0.23

0.23

0.23

n-Butane

0

0

0

0

0

0

0

0

0

Iso-Butane

0

0

0

0

0

0

0

0

0

Ethylene

0

0.04

0.04

0.04

0.04

0.04

0.04

0.04

0.04

Ethane

0

0.01

0.01

0.01

0.01

0.01

0.01

0.01

0.01

Methane

0

0.06

0.06

0.06

0.06

0.06

0.06

0.06

0.06

Hydrogen

0

0.22

0.22

0.22

0.22

0.22

0.22

0.22

0.22

71

Stream Number

19

20

21

22

23

24

25

26

27

Temperature (°C)

100

50

75

119

5

5

5

-40

70

65

65

65

65

25

28

Pressure (Bar)

11.306 11.306 19.652

Component composition Propane

0.44

0.44

0.44

0.44

0.44

0.074

0.552

0

0.63

Propylene

0.23

0.23

0.23

0.23

0.23

0.049

0.292

0

0.37

n-Butane

0

0

0

0

0

0

0

0.3973

0

Iso-Butane

0

0

0

0

0

0

0

0

0

Ethylene

0.04

0.04

0.04

0.04

0.04

0.03

0.043

0.6027

0

Ethane

0.01

0.01

0.01

0.01

0.01

0.008

0.011

0

0

Methane

0.06

0.06

0.06

0.06

0.06

0.107

0.044

0

0

Hydrogen

0.22

0.22

0.22

0.22

0.22

0.721

0.048

0

0

Stream Number

28

29

30

Temperature (°C)

45

57.24

65

Pressure (Bar)

18

20

25

Component composition Propane

0.005

0.995

0.995

Propylene

0.995

0.005

0.005

n-Butane

0

0

0

Iso-Butane

0

0

0

Ethylene

0

0

0

Ethane

0

0

0

Methane

0

0

0

Hydrogen

0

0

0

72

References •

Felder, R. M., Rousseau, R. W., & Bullard, L. G. (2020). Elementary principles of chemical processes. John Wiley & Sons.

73

3

Simulation

74

Introduction In chemical engineering, simulation programs such as Aspen HYSYS are powerful and essential tools that are used to design chemical plants. This tool gives the engineer an overview about challenges that will be encountered before building the plant in real-life. Moreover, engineers use Aspen HYSYS to ensure that the process is operated safely, optimally, and to minimize the cost. In this chapter, Aspen HYSYS will be used to simulate Propane Dehydrogenation Process (PDH).

A complete analysis will be provided for 4 reactors, 1 Depropanizer, 1 Deethanizer, 1 splitter, 4 fired heaters, 3 compressors, 5 heat exchangers, 4 coolers, 3 condensers, 3 reboilers.

Fluid Package The starting point after choosing components and reactions of the process is to choose a proper fluid package. The choice of the fluid package plays an essential rule on accuracy of calculated parameters. In simulation analysis, Peng-Robinson (PR) fluid package has been used for several reasons such as it accommodates high range of pressure and temperature which is the case for propane dehydrogenation. For pressure, a range of 1000 bar or less is applicable to Peng-Robinson fluid package. For temperature, a range of -271 oC or more is also applicable to choose PengRobinson as fluid package. Moreover, Peng-Robinson can be applied to polar and nonpolar components which is the case in PDH process.

Figure 27:Fluid package selection.

75

Process Flow Diagram (PFD)

76

Plug Flow Reactor (R-101, R-102, R-103, and R-104) Generally, plug flow reactors are introduced to produce propylene from propane. Also, the requirements and the desired specifications can influence several factors such as reactor volume, number of reactors, and configuration of the reactors. In our case, four plug flow reactors were installed in series to meet the desired requirements, which are 400 tones/year with purity of 99.5%.

However, platinum-based catalyst is used in all reactors to dehydrogenate propane and produce propylene and other impurities. In addition, the reactors were designed to perform at 650 oC and 3 bars with overall single pass conversion of 36.41% and selectivity of 0.9359. To operate at these conditions, fired heater was placed before the reactor to heat up the feed. Since the reactions are endothermic, fired heaters were introduced between each reactor to achieve the optimum temperature of the reactions.

Figure 28: Plug flow reactor (R-101).

Figure 29: Dimensions of R-101.

77

Figure 30: Inlet compositions for each component.

Figure 31: outlet compositions for each component

78

Figure 32: Plug flow reactor (R-102).

Figure 33: Dimensions of R-102.

Figure 34: Inlet compositions for each component.

79

Figure 35: outlet compositions for each component

80

Figure 36: Plug flow reactor (R-103).

Figure 37: Dimensions of R-103.

Figure 38: Inlet compositions for each component.

81

Figure 39: outlet compositions for each component

82

Figure 40: Plug flow reactor (R-104).

Figure 41: Dimensions of R-104

Figure 42: Inlet compositions for each component.

83

Figure 43: outlet compositions for each component

84

Previously, the reactors were designed to operate at 3 bar and 650 oC to achieve our target, which is producing 400 tons/ year of propylene with 99.5%. However, several operating and designing parameters can have a large impact on the conversion, selectivity, production, and the cost such as the operating temperature, pressure, and reactor volume. Thus, studies have been conducted to observe the effect of changing the temperature, pressure, volume of the reactors against percentage of conversion and selectivity. It is worth to mention the constrains of our reactors, first, the conversion has a range between 35-40%. Second, the selectivity shouldn’t be below 80%. Third, it is recommended for utilizing the catalyst to operate at pressure between 0.5 to 3.5 bar and temperature between 500 to 650 °C.

Case I: Effect of Changing Temperature of The Reactors Table 40: Temperature change effect on conversion.

Case

T oC

Sp

Conversion

1 2 3 4 5 6 7

500 550 600 650 700 750 800

1.030644 1.004736 0.975971 0.935916 0.876681 0.793895 0.690414

10.95% 17.30% 26.09% 36.40% 48.73% 74.60% 73.07%

80% 70%

Conversion (%)

60% 50% 40% 30% 20% 10% 0% 400

500

600

700

800

900

T (C) Figure 44: Conversion vs temperature.

85

1.2

Selectivity

1 0.8 0.6 0.4 0.2 0 400

500

600

700

800

900

T (C)

Figure 45: Selectivity vs temperature.

As illustrated in Figure 44Figure 45, the experiment was to evaluate the effect of changing the temperature while fixing operating at 3 bar and 24.74 m3 on the conversion and selectivity.

Moreover, as the temperature increases the conversion will be increased while the selectivity will decrease. As results of increasing in the production of impurities, high consumption of propane, and decreasing in net production rate.

Case II: Effect of Changing Pressure of The Reactors Table 41: Change in pressure effect on conversion.

P bar 1.5 2 2.5 3 3.5 4 4.5 6 7

Sp Conversion 0.92625 14.93% 0.92666 21.86% 0.93096 29.42% 0.93592 36.40% 0.93969 42.58% 0.94357 48.15% 0.94709 52.79% 0.95394 63.97% 0.95662 69.54%

86

80% 70%

Conversion (%)

60% 50% 40%

30% 20% 10% 0% 0

1

2

3

4

5

6

7

8

6

7

8

P (bar)

Figure 46: Conversion vs Pressure.

1 0.95

Selectivity

0.9 0.85 0.8 0.75 0.7 0

1

2

3

4

5

P (bar)

Figure 47: Selectivity vs Pressure.

In Figure 46 and Figure 47, the study was to evaluate the effect of changing the pressure while fixing operating at 650 oC and 24.74 m3 on the conversion and selectivity. In addition, increasing the pressure results a high conversion percentage, but it doesn’t have a large influence on selectivity.

Due to high consumption of propane and less production of impurities relatively to change in temperature production.

87

Case III: Effect of Changing Volume of The Reactors

Table 42: Change on volume effect on conversion.

V 14.14 21.21 24.74 31.81 38.88 49.48

Sp Conversion 0.92513 23.86% 0.93227 30.93% 0.93592 36.40% 0.943 47.07% 0.94812 54.93% 0.95391 64.45%

0.96 0.955

Selectivity

0.95 0.945 0.94 0.935 0.93 0.925 0.92 0

10

20

30

40

50

60

V (m3)

Figure 48: Selectivity vs Volume.

88

70% 60%

Conversion(%)

50% 40% 30%

20% 10% 0% 0

10

20

30

V

40

50

60

(m3)

Figure 49: Conversion vs Volume.

According to Figure 48 Figure 49, the evaluation was to study the effect of changing the volume of the reactors while fixing operating at 650 oC and 3 bar on the conversion and selectivity.

However, increasing reactor volume has a positive effect on conversion percentage and selectivity.

Also, it is impractical in the industry to install four massive reactors in series. Moreover, optimum sizing of the reactor will be discussed in the next chapter.

89

Distillation Columns (T-101, T-102, T-103) & Flash Drum (V-101)

Figure 50: Depropanizer (T-101).

The main purpose of using T-101 is to separate propane from butane. It has been found from Aspen HYSYS that number of equilibrium stages to reach the desired composition of propane (99.24%) is 23 stages without reboiler stage. Also, the feed enters T-101 at stage 11 which is the optimum feed stage. Moreover, the feed temperature and pressure are 46.74 oC and 1100 KPa respectively. Furthermore, the reflux ratio is assumed to be 1.745. In addition, the temperature of the first stage (stage one) at the top of the tower is 46.27 oC. Also, the temperature of the last stage (stage 23) at the bottom of the tower is 94.33 oC.

90

Figure 51: Temperature vs tray position of T-101.

Figure 52: temperature profile.

Figure 53: Figure 4: pressure vs tray position of T-101.

91

Figure 54: Pressure profile.

Figure 55: Compositions of distillate of T-101.

Figure 56: Heat duty for condenser of T-101.

Figure 57: Heat duty for reboiler of T-101.

Table 43: Percentage error for the most volatile component at distillate.

Component Propane

Value from

Value

Aspen HYSYS

0.9924

Mass balance

0.995

Error % 0.26

92

Figure 58: Flash drum (V-101).

Table 44: Conditions around the drum.

Table 45: the molar flow and the mole fraction of the liquid stream (stream 32).

Component

Molar Flow (kmol/h)

Mole Fraction

Propane

1847.316

0.6168

Propylene

1090.18

0.364

Methane

22.76

0.0076

Ethane

0

0

Ethylene

34.74

0.0116

Hydrogen

0

0

93

Table 46: Molar flow and the mole fraction of the vapor stream (stream 31).

Component

Molar Flow (Kmol/H)

Mole Fraction

Propane

89.70

0.0774

Propylene

67.21

0.058

Methane

20.55

0.0177

Ethane

0

0

Ethylene

8.71

0.0075

Hydrogen

972.51

0.8391

Table 47: Comparison between the calculated values and the values obtained from HYSYS.

Calculated

Aspen HYSYS

%Error

Components Liquid

Vapor

Liquid

Vapor

Liquid

Vapor

Propane

0.552

0.074

0.6168

0.0774

10.45

4.45

Propylene

0.292

0.049

0.364

0.058

19.76

14.99

Ethylene

0.043

0.030

0.0076

0.0177

100.00

68.54

Ethane

0.011

0.008

0

0

100.00

100.00

Methane

0.044

0.107

0.0116

0.0075

100.00

93.02

Hydrogen

0.048

0.721

0

0.8391

100.00

14.02

94

Figure 59: Deethanizer (T-102).

The main purpose of using T-102 is to separate propane and propene from methane, and ethylene. It has been found from Aspen HYSYS that number of equilibrium stages is 26 stages without reboiler stage. Also, the feed enters T-102 at stage 13 which is the optimum feed stage.

Furthermore, the feed temperature and pressure are -0.1373 oC and 2500 KPa respectively. And the reflux ratio was 109.7. In addition, the temperature of the first stage (stage one) at the top of the tower is -26.19oC. Also, the temperature of the last stage (stage 26) at the bottom of the tower is 69.64 oC.

Figure 60: Temperature profile throughout the column.

95

Table 48: Compitions of the feed, distillte, and the bottom of T-102.

Stream No.

35

36

38

Propane

0.6168

0.03

0.68

Propylene

0.364

0

0.37

Ethylene

0.0116

0.59

0

Ethane

0

0

0

Methane

0.0076

0.38

0

Hydrogen

0

0

0

i-Butane

0

0

0

n-Butane

0

0

0

Table 49:Feed, distillate, and bottom flowrates comparison of T-102

Component

Calculated (kmol/h) F

D

Propane

1755.00

1.75

Propylene

928.08

Ethylene

B

Aspen HYSYS (kmol/h) F

%Error

D

B

F

D

B

1753.24 1832.30

0.00

1832.30

4.22

100.00

4.31

0.00

928.08

1089.56

0.00

1089.55

14.82

100.00

14.82

138.20

138.06

0.14

34.72

34.71

0.00

100.00 100.00 100.00

Ethane

33.85

33.85

0.00

0.00

0.00

0.00

100.00 100.00

0.00

Methane

138.87

138.87

0.00

22.88

22.88

0.00

100.00 100.00

0.00

96

Figure 61: Propane/Propylene Splitter.

The main purpose of using T-103 is to separate Propane and Propene from each other. The required Propene purity is (99.5%) and it has been found from Aspen HYSYS that number of equilibrium stages to reach the desired composition of Propene (99.5%) is 145 stages without reboiler stage. Also, the feed enters T-103 at stage 86 which is the optimum feed stage. Moreover, the feed temperature and pressure are 53.38 oC and 2000 KPa respectively. Furthermore, the reflux ratio was assumed to be 2.5. In addition, the temperature of the first stage (stage one) at the top of the tower is 45.18 oC. Also, the temperature of the last stage (stage 145) at the bottom of the tower is 57.24 oC.

Figure 62: Temperature profile.

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Figure 63: Pressure profile.

Figure 64: Compositions of distillate of T-103.

Figure 65: Heat duty for condenser of T-103.

Figure 66: Heat duty for reboiler of T-103.

Table 50: Percentage error for the most volatile component at distillate.

Component Propylene

Value from

Value

Aspen HYSYS

0.995

Mass balance

0.995

Error % 0

98

Heat Exchangers

Figure 67: Heat exchanger E-101.

The main purpose of using shell and tube heat exchanger E-101 is to cool or heat the fluid.

Also, E-101 is consist of 2 tube passes and 1 shell pass. Moreover, the propane will be heated up by utilizing the hot effluent stream coming out of the reactor. In addition, heating the propane will help the Depropanizer to separate the propane from the butane and to change the stream phase to vapor.

Figure 68: Design parameters of E-101.

Figure 69: Details of E-102 performance.

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Table 51: Heat duty comparison for E-101.

Calculated (kJ/h) 23400000

Aspen (kJ/h) 23990000

% Error 2.45

Heating Side Feed to the shell side LPG consists of propane, propene, iso-butane, and n-butane which will be heated by the tube side. Results in the heat lost from the tube side is gained by the shell side. The LPG is heated from 44.24 oC to 46.74 oC in order to achieve an efficient separation process.

Cooling side Tube side which is from heat exchanger (E-102) is considered as the cooling side. The tube side consists of propane, propene, methane, ethylene, and hydrogen. In addition, temperature of the mixture contained in tube side is cooled from 287.16 oC to 223.84 oC.

Figure 70: Heat exchangers E-102, E-103, E-104, and E-105 respectively.

The propane dehydrogenation process is an endothermic process which means that a heat is needed in order to increase the temperature of the system allowing the reaction to take place.

Unfortunately, using the heat exchanger only is not enough to achieve the reaction condition (650 oC). However, using a series of heat exchangers have the advantage of saving a lot of money by reducing the duty of the fired heater used before the reactor series. Each one of the heat exchanger series consists of 2 tube passes and one shell pass is used, where the effluent from the reactor is entered in the tube side while the shell side is filled with the distillate stream from T-101.

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Figure 71: Design parameters of E-102.

Figure 72: Details of E-102 performance.

Table 52: Heat Duty comparison for E-102.

Calculated (kJ/h) 6.21E+07

Aspen (kJ/h) 6.083E+07

% Error 2.05

Figure 73:Design parameters of E-103.

101

Figure 74: Details of E-103 performance.

Table 53: Heat duty comparison for E-103.

Calculated (kJ/h) 2.2334E+07

Aspen (kJ/h) 2.287E+07

% Error 2.39

Figure 75:Design parameters of E-104.

Figure 76: Details of E-104 performance.

Table 54: Heat duty comparison for E-104.

Calculated (kJ/h) 2.699E+07

Aspen (kJ/h) 2.639E+07

% Error 2.22

102

Figure 77:Design parameters of E-105.

Figure 78: Details of E-105 performance.

Table 55: Heat duty comparison for E-105.

Calculated (kJ/h) 3.04E+07

Aspen (kJ/h) 2.974E+07

% Error 2.17

103

Heating Side The input for the heating side is the distillate from T-101, which consists mainly of propane.

This stream is aiming to enter the reactor at 650 oC. The reactor feed conditions cannot be achieved by installing a series of heat exchangers only, therefore a furnace is implemented afterwards. In order to increase the temperature, the heat from the stream to be cooled is used here for better economic reasons and to achieve the maximum profitability. As a consequence of the heat exchanger series installation, the furnaces will be smaller in shape and cheaper. The inlet temperature of the heat exchanger series will be -13.63 oC and the outlet temperature will be 320 oC.

Cooling Side The input stream for cooling side is the effluent from the reactor, which consists of propane, propylene, ethane, ethylene, and hydrogen. The aim is to quench the effluent stream temperature from 593.11 oC to 287.16 oC before it is further quenched in E-101 to meet the conditions of the T102. Furthermore, it is used to increase the temperature of the reactor feed and therefore, the heat lost will be gained by the reactor feed stream.

104

Coolers (E-106, E-107, E-108, and E-109)

Figure 79: Coolers E-106, E-107, E-108, and E-109 respectively.

The purpose of using four coolers in series is to decrease the temperature of the outlet stream of (E-101) from 223.84 oC to 5 oC in order to enable deethanizer (T-102) to separate propane and propylene from impurities which are: methane, ethylene and hydrogen. For the first cooler (E-106), the temperature decreased from 223.84 oC to 150 oC. For the second cooler (E-107), the temperature decreased from 252.49 oC to 150 oC. For the third cooler (E-108), the temperature decreased from 150 oC to 23.88oC. For the fourth cooler(E-109), the temperature decreased from 119.40 oC to 5oC.

Figure 80: Design parameters of E-106.

Figure 81: Design parameters of E-107.

Figure 82: Design parameters of E-108.

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Figure 83: Design parameters of E-109.

Table 56: Heat Duty comparison for E-106.

Calculated (kJ/h) 2.693E+07

Aspen (kJ/h) 2.548E+07

% Error 5.38

Table 57: Heat Duty comparison for E-107.

Calculated (kJ/h) 3.913E+07

Aspen (kJ/h) 3.669E+07

% Error 12.97

Table 58: Heat Duty comparison for E-108.

Calculated (kJ/h) 4.212E+07

Aspen (kJ/h) 3.859E+07

% Error 8.38

Table 59: Heat Duty comparison for E-109.

Calculated (kJ/h) 2.222E+07

Aspen (kJ/h) 6.890E+07

% Error 67.75

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Fired Heaters

Figure 84: Fired heater H-101.

In order to achieve the desired temperature for the reaction, a fired heater is used. Fired heater uses air and fuel stream (pure Methane) to heat up reactants to the desired temperature which is 650 oC. For H-101, it heats reactants from 320 oC to the desired temperature.

Figure 85: Conditions of H-101.

Heat duty of fired heater (H-101) has been found using Aspen HYSYS to be equal to 1.523*108 KJ/h

Figure 86: Heat duty of H-101.

107

Figure 87: Fired heater H-102.

For H-102, it heats reactants from 561.70 oC to 650 oC.

Figure 88: Conditions of H-102.

Heat duty of fired heater (H-102) has been found using Aspen HYSYS to be equal to 4.482*107 KJ/h, which is much lower than heat duty for H-101, because of small difference in temperature between inlet and outlet streams.

Figure 89: Heat duty of H-102.

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Figure 90: Fired heater H-103.

For H-103 it heats reactants from 575.64 oC to 650 oC.

Figure 91: Conditions of H-103.

Heat duty of fired heater (H-103) has been found using Aspen HYSYS to be equal to 3.793*107 KJ/h, which is also lower than heat duty for H-102, because that the reaction is near to reaction completion more than in second reactor. Moreover, temperature difference is lower than temperature difference in H-102.

Figure 92: Heat duty of H-103.

109

Figure 93: Fired heater H-104.

For H-104, it heats reactants from 586.41 oC to 650 oC.

Figure 94: Conditions of H-104.

Heat duty of fired heater (H-104) has been found using Aspen HYSYS to be equal to 3.256*107 KJ/h, which is also lower than heat duty for H-101, H-102, and H-103 because the reaction is near to completion state. Moreover, temperature difference is lower than temperature difference in H101, H-102, and H-103.

Figure 95: Heat duty of H-104.

110

Compressors

Figure 96: Compressor C-101

The aim of the compressor is to raise the gas pressure by reducing its volume and concentrates the heat contained. The C-101 is implemented to increase the pressure of the stream coming out of the reactor from 304 kPa to 1500 kPa. The outlet of the compressor is passed to E-107 to cool down before it recompressed in the second compressor. The calculated power of the compressor by Aspen HYSYS found to be 9.6945𝑒 + 03 kW with compressor efficiency of 75%.

Figure 97: Parameters of C-101.

Figure 98: C-101 Conditions.

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Table 60: Comparison for compressor duty of C-101.

C-101 Power (kW)

Calculated 9800.148481

Aspen HYSYS 9694.50

%Error 1.08

Figure 99: Compressors C-102 & C-103.

As previously mentioned, what the compressors are installed for, the second compressor C102 was implemented to increase the pressure from 1500 kPa to 4000 kPa. The outlet stream of E108 is fed to the compressor to increase the pressure of the stream before it is fed to the third compressor for further compressing. C-103 is installed right after C-102 in order to increase the stream pressure entering E-109 then to the vessel from 4000 kPa to 6500 kPa. The calculated power of the compressors C-102 and C-103 from aspen hysys are found to be 3.4754𝑒 + 03 kW and 1.8984𝑒 + 03, respectively with compressor efficiency of 75% for both.

Figure 100: Parameters of C-102.

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Figure 101: C-102 Conditions.

Figure 102: Parameters of C-103.

Figure 103: C-103 Conditions.

Table 61: Comparison for compressor duty of C-102.

C-102 Power (kW)

Calculated 4288.639179

Aspen HYSYS 3475.40

%Error 18.96264

Table 62: Comparison for compressor duty of C-103.

C-103 Power (kW)

Calculated 1983.377558

Aspen HYSYS 1898.40

%Error 4.284487

113

4

Equipment Design

114

4.1

Reactor Design

By: Ali Alamri

115

Introduction Reactor is the most essential equipment in chemical industries. There are many types of reactors that can be used in industry such as batch reactor (BR), continuous stirred tank reactor (CSTR), plug flow reactor (PFR), and packed bed reactor (PBR). In our case, the production of propylene is carried through the propane dehydrogenation process. However, the process reactions are categorized as endothermic reactions and this process takes a place in the presence of platinum on alumina catalyst (Pt/Al2O3). Furthermore, the feed components to the plug flow reactors are propane, residual iso-butane, n-butane, and recycled propene. However, the residual of iso-butane and n-butane will not be taken into account in sizing the reactor since the mentioned reactions will not involve them. In Propane Dehydrogenation process (PDH), a series of four plug flow reactors are used to derive the following reactions:

The main reaction: 𝐶3 𝐻8

𝑘11

→ ←

𝑘−1

𝐶3 𝐻6 + 𝐻2

The side reactions: 𝑘2

𝐶3 𝐻8 → 𝐶𝐻4 + 𝐶2 𝐻4 𝑘3

𝐶2 𝐻4 + 𝐻2 → 𝐶2 𝐻6 It is required to calculate diameter, length, and volume of each reactor. In addition, final temperature of the outlet stream of each reactor is to be found by applying energy balance around the reactor.

Figure 104: PFR schematic diagram.

Before starting to design the plug flow reactors, several assumptions will be considered.

Moreover, assumptions for designing the reactors are listed below:

116

1.

2.

3.

4.

5.

6.

7.

Steady-State system.

Infinite mixing in radial direction and absence of mixing in axial direction (ideal PFR).

Adiabatic.

Pressure drop is insignificant and can be neglected.

Only consist of three gas phase reactions.

Residual iso-butane and n-butane will not be involved in the reactions.

The bulk density of the catalyst equals 700 kg/m3.

Reactor design follows well known algorithms steps that is mentioned below: 1.

2.

3.

4.

5.

Individual mole balance for each component must be performed.

Write for each component the net rate laws.

Write the stoichiometry equations.

Combine the rate laws and mole balances.

Apply energy balance on the reactor.

Figure 105: algorithms of reactor sizing.

Three reactions undergo inside the reactors are mentioned below

𝑘11

𝐶3 𝐻8 ←→ 𝐶3 𝐻6 + 𝐻2 (𝐷𝑒𝑠𝑖𝑟𝑒𝑑 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛) 𝑘−1

𝑘2

𝐶3 𝐻8 → 𝐶𝐻4 + 𝐶2 𝐻4 (𝑈𝑛𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛) 𝑘3

𝐶2 𝐻4 + 𝐻2 → 𝐶2 𝐻6 (𝑈𝑛𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑅𝑒𝑎𝑐𝑡𝑖𝑜𝑛)

For simplicity,

117

A

k11

→ ←

k−1

B+C

k2

A→ D+E k3

E+C→ F

Where, A: Propane (C3H8) B: Propylene (C3H6) C: Hydrogen (H2) D: Methane (CH4) E: Ethylene (C2H4) F: Ethane (C2H6)

the general mole balance formula of a reactive system can be described as:

𝐴𝑐𝑐𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑜𝑛 = 𝐼𝑛𝑝𝑢𝑡 − 𝑂𝑢𝑡𝑝𝑢𝑡 + 𝐺𝑒𝑛𝑒𝑟𝑎𝑡𝑖𝑜𝑛 − 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 Since the system is operated at steady state, thus, accumulation term can be set to zero: 0 = 𝐹𝑖 |𝑧 − 𝐹𝑖 |𝑧+∆𝑧 + 𝑟𝑖 ∆𝑉

Take the limit as ∆z approaches zero 𝐹𝑖 |𝑧+∆𝑧 − 𝐹𝑖 |𝑧 = 𝑟𝑖 ∆𝑧 →0 ∆𝑉 lim

Thus, 𝑑𝐹𝑖 = 𝑟𝑖 𝑑𝑉

118

For Propane (A), 𝑑𝐹𝐴 = 𝑟𝐴,𝑁𝐸𝑇 𝑑𝑉

For Propylene (B), 𝑑𝐹𝐵 = 𝑟𝐵,𝑁𝐸𝑇 𝑑𝑉

For Hydrogen (C), 𝑑𝐹𝐶 = 𝑟𝐶,𝑁𝐸𝑇 𝑑𝑉

For Methane (D), 𝑑𝐹𝐷 = 𝑟𝐷,𝑁𝐸𝑇 𝑑𝑉

For Ethylene (E), 𝑑𝐹𝐸 = 𝑟𝐸,𝑁𝐸𝑇 𝑑𝑉

For Ethane (F), 𝑑𝐹𝐹 = 𝑟𝐹,𝑁𝐸𝑇 𝑑𝑉

Where, Fi: molar flowrate (kmol/hr).

V: volume of the reactor (m3). ri: rate of the reaction (kmol/ (m3 hr)).

119

The rate law for the first reaction is defined as −𝑟1 = 𝑘1 (𝑃𝐴 −

𝑃𝐵 𝑃C ) 𝐾𝑒𝑞

And the rate constants for the first reaction are

𝑘1 (

𝑘𝑚𝑜𝑙 3846.28 ) = 13.920 exp (− ) 𝑘𝑔. ℎ𝑟. 𝑘𝑃𝑎 𝑇

𝐾𝑒𝑞 (𝑘𝑃𝑎) = 1.47 ∗ 107 exp (−

15403 ) 𝑇

The rate law for the second reaction is described as:

−𝑟2 = 𝑘2 𝑃𝐴

Where the rate constant for the second reaction rate is

𝑘2 (

kmol 17072.41 ) = 1.573 ∗ 106 𝑒𝑥𝑝 (− ) kg. hr. kPa 𝑇

Finally, reaction rate for the third reaction can be defined as:

−𝑟3 = 𝑘3 𝑃𝐸 𝑃C

Moreover, the rate constant for the third reaction rate is kmol 17970.89 𝑘3 ( ) = 3.3965 exp (− ) kg. hr. kPa2 𝑇 Before moving forward, to be consistent with the simulation section, thus, the constant rate coefficients (k1, k2, and k3) were multiplied by the bulk density of the catalyst which equals 700 kg/m3.

120

For reaction (1): 𝑟1𝐴 𝑟1𝐵 𝑟1𝐶 = = −1 +1 +1 For reaction (2): 𝑟2𝐴 𝑟2𝐷 𝑟2𝐸 = = −1 +1 +1 For reaction (3): 𝑟3𝐸 𝑟3𝐶 𝑟3𝐹 = = −1 −1 +1 Thus, the net rates for all components are mentioned below. 𝑟𝐴,𝑁𝐸𝑇 = 𝑟1𝐴 + 𝑟2𝐴 = −𝑘1 (𝑃𝐴 −

𝑟𝐵,𝑁𝐸𝑇 = 𝑟1𝐵 = 𝑘1 (𝑃𝐴 −

𝑟𝐶,𝑁𝐸𝑇 = 𝑟1𝐶 + 𝑟3𝐶 = 𝑘1 (𝑃𝐴 −

𝑃𝐵 𝑃C ) − 𝑘2 𝑃𝐴 𝐾𝑒𝑞 𝑃𝐵 𝑃C ) 𝐾𝑒𝑞

𝑃𝐵 𝑃C ) − 𝑘3 𝑃𝐸 𝑃C 𝐾𝑒𝑞

𝑟𝐷,𝑁𝐸𝑇 = 𝑟2𝐷 = 𝑘2 𝑃𝐴 𝑟𝐸,𝑁𝐸𝑇 = 𝑟2𝐸 + 𝑟3𝐸 = 𝑘2 𝑃𝐴 − 𝑘3 𝑃𝐸 𝑃C 𝑟𝐹,𝑁𝐸𝑇 = 𝑟3𝐹 = 𝑘3 𝑃𝐸 𝑃C Table 63: inlet molar flowrates of the components

Initial molar flow rates 𝐹𝐴𝑂 𝐹𝐵𝑂 𝐹𝐶𝑂 𝐹𝐷𝑂 𝐹𝐸𝑂 𝐹𝐹𝑂 𝐹𝑖𝑠𝑜−𝑏𝑢𝑡𝑎𝑛𝑒 𝐹𝑛−𝑏𝑢𝑡𝑎𝑛𝑒 𝐹𝑇𝑂

𝑘𝑚𝑜𝑙 ( ) ℎ𝑟 3113.9663 8.2448 0 0 0 0 15.1106 0.5661 3137.8878

121

The inlet molar flow rate entering the reactor can be found using the following formula: 𝐹𝑇𝑂 = 𝐹𝐴𝑂 + 𝐹𝐵𝑂 + 𝐹𝐶𝑂 + 𝐹𝐷𝑂 + 𝐹𝐸𝑂 + 𝐹𝐹𝑂 + 𝐹𝑖𝑠𝑜−𝑏𝑢𝑡𝑎𝑛𝑒 +𝐹𝑛−𝑏𝑢𝑡𝑎𝑛𝑒 = 3137.8878

𝑘𝑚𝑜𝑙 𝑘𝑚𝑜𝑙 = 0.8716 ℎ𝑟 𝑠

Similarly, the outlet molar flowrate exiting the reactor is attained from Aspen HYSYS:

𝐹𝑇 = 𝐹𝐴 + 𝐹𝐵 + 𝐹𝐶 + 𝐹𝐷 + 𝐹𝐸 + 𝐹𝐹 + 𝐹𝑖𝑠𝑜−𝑏𝑢𝑡𝑎𝑛𝑒 + 𝐹𝑛−𝑏𝑢𝑡𝑎𝑛𝑒 Ideal gas law is used to obtain volumetric flow rate which is expressed by: 𝐹𝑇𝑂 𝑅𝑇𝑜 𝑚3 𝑚3 𝜈𝑜 = = 79209.24 = 22 𝑃𝑜 ℎ𝑟 𝑠 Where, 𝐹𝑇𝑂 = 3137.89

𝑘𝑚𝑜𝑙 ℎ𝑟

𝑃𝑜 = 304000 𝑝𝑎 𝑇𝑜 = 923 𝐾 𝑅 = 8314

𝑝𝑎. 𝑚3 𝑘𝑚𝑜𝑙. 𝐾

For calculating outlet volumetric flow rate, first relating equations must be applied. First, inlet volumetric flowrate equation can be defined as: 𝜈𝑜 =

𝐹𝑇𝑂 𝑅𝑇𝑜 𝑃𝑜

In the same manner, outlet volumetric flowrate given by: 𝜈=

𝐹𝑇 𝑅𝑇 𝑃

Dividing the two equation gives: 𝜈 𝑃𝑜 𝐹𝑇 𝑇 = ( )( )( ) 𝜈𝑜 𝑃 𝐹𝑇𝑂 𝑇𝑜

122

Since the pressure drop is neglected: 𝑃𝑜 ( )=1 𝑃 Thus, 𝜈 = 𝜈𝑜 (

𝐹𝑇 𝑇 )( ) 𝐹𝑇𝑂 𝑇𝑜

Ideal gas law is used to calculate total initial concentration by using the following formula: 𝐶𝑇𝑜 =

𝑃𝑜 𝑅𝑇

𝐶𝑇 =

𝑃 𝑅𝑇

Similarly, for the total final concentration:

For any species concentration it is found using below equation: 𝐶𝑖 =

𝑝𝑖 𝑅𝑇

Pressure of any species at time t is given as: 𝑝𝑖 =

𝐹𝑖 𝑅𝑇 𝜈

After simplifying the equations, it ended up with: 𝐶𝑖 = 𝐶𝑇𝑜 (

𝐹𝑖 𝑇𝑜 )( ) 𝐹𝑇 𝑇

Therefore, 𝐶𝐴 = 𝐶𝑇𝑜 (

𝐹𝐴 𝑇𝑜 )( ) 𝐹𝑇 𝑇

𝐶𝐵 = 𝐶𝑇𝑜 (

𝐹𝐵 𝑇𝑜 )( ) 𝐹𝑇 𝑇

𝐹𝐶 𝑇𝑜 𝐶𝐶 = 𝐶𝑇𝑜 ( )( ) 𝐹𝑇 𝑇 𝐶𝐷 = 𝐶𝑇𝑜 (

𝐹𝐷 𝑇𝑜 )( ) 𝐹𝑇 𝑇

𝐹𝐸 𝑇𝑜 𝐶𝐸 = 𝐶𝑇𝑜 ( )( ) 𝐹𝑇 𝑇

123

𝐶𝐹 = 𝐶𝑇𝑜 (

𝐹𝐹 𝑇𝑜 )( ) 𝐹𝑇 𝑇

In terms of pressure, 𝑝𝐴 =

𝐹𝐴 𝑅𝑇 𝜈

𝑝𝐵 =

𝐹𝐵 𝑅𝑇 𝜈

𝑝𝐶 =

𝐹𝐶 𝑅𝑇 𝜈

𝑝𝐷 =

𝐹𝐷 𝑅𝑇 𝜈

𝑝𝐸 =

𝐹𝐸 𝑅𝑇 𝜈

𝑝𝐹 =

𝐹𝐹 𝑅𝑇 𝜈

Generally, 𝑑𝑇 𝑈𝑎 (𝑇𝑎 − 𝑇) + ∑𝑅𝑗=1[−∆𝐻𝑅𝑋𝑁 (𝑇)]𝑗 (−𝑟𝑗 ) = ∑𝑛𝑖=1 𝐹𝑖 𝐶𝑝𝑖 𝑑𝑉 Since the system is adiabatic and non-isothermal.

𝑑𝑇 [−∆𝐻𝑅𝑋𝑁 (𝑇)]1 (−𝑟1 ) + [−∆𝐻𝑅𝑋𝑁 (𝑇)]2 (−𝑟2 ) + [−∆𝐻𝑅𝑋𝑁 (𝑇)]3 (−𝑟3 ) = 𝑑𝑉 𝐹𝐴 𝐶𝑝𝐴 + 𝐹𝐵 𝐶𝑝𝐵 + 𝐹𝐶 𝐶𝑝𝐶 + 𝐹𝐷 𝐶𝑝𝐷 + 𝐹𝐸 𝐶𝑝𝐸 + 𝐹𝐹 𝐶𝑝𝐹

124

𝐶𝑝,𝑖 = 𝐴𝑖 + 𝐵𝑖 𝑇 + 𝐶𝑖 𝑇 2 + 𝐷𝑖 𝑇 3 Table 64: Species with their values of Cp.

Species Propane A Propylene B Ethylene E Ethane F Methane D Hydrogen C

Cp (kJ/mol K) (68.03 ∗ 10 + (22.59 ∗ 10 + (−13.11 ∗ 10−8 )𝑇 2 + (31.71 ∗ 10−12 )𝑇 3 (59.58 ∗ 10−3 ) + (17.71 ∗ 10−5 )𝑇 + (−10.17 ∗ 10−8 )𝑇 2 + (24.60 ∗ 10−12 )𝑇 3 (40.75 ∗ 10−3 ) + (11.47 ∗ 10−5 )𝑇 + (−6.89 ∗ 10−8 )𝑇 2 + (17.66 ∗ 10−12 )𝑇 3 (49.37 ∗ 10−3 ) + (13.92 ∗ 10−5 )𝑇 + (−5.82 ∗ 10−8 )𝑇 2 + (7.28 ∗ 10−12 )𝑇 3 (34.31 ∗ 10−3 ) + (5.47 ∗ 10−5 )𝑇 + (0.37 ∗ 10−8 )𝑇 2 + (−11.00 ∗ 10−12 )𝑇 3 (28.84 ∗ 10−3 ) + (0.01 ∗ 10−5 )𝑇 + (0.33 ∗ 10−8 )𝑇 2 + (−0.87 ∗ 10−12 )𝑇 3 −3 )

−5 )𝑇

68.03*10-3+22.59*10-5T+-13.11*10-8T2+31.71*10-12T3

For standard heat of formation for each reaction, the following formula will be used:

𝑜 ∆𝐻𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 = ∑ ∆𝐻𝑓𝑜 (𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑠) − ∑ ∆𝐻𝑓𝑜 (𝑅𝑒𝑎𝑐𝑡𝑎𝑛𝑡𝑠)

Table 65: Heat of formation values of A, B, C, D, E, and F.

Compound ∆Ĥ°f (kJ/mol)

A -103.8

B 20.41

C 0

D -74.85

E 52.28

F -84.67

Reaction (1): 𝑜 ∆𝐻𝑟,1 = (∆𝐻𝑓𝑜 )𝐵 + (∆𝐻𝑓𝑜 )𝐶 − (∆𝐻𝑓𝑜 )𝐴 𝑜 ∆𝐻𝑟,1 = 20.41 + 0 − (−103.8) = 124.21

𝑘𝐽 𝐽 = 124210000 𝑚𝑜𝑙 𝑘𝑚𝑜𝑙

𝑇

[∆𝐻𝑅𝑋𝑁 (𝑇)]1 =

𝑜 ∆𝐻𝑟,1

+ ∫ 𝐶𝑝𝐵 + 𝐶𝑝𝐶 − 𝐶𝑝𝐴 𝑑𝑇 298

125

Reaction (2): 𝑜 ∆𝐻𝑟,2 = (∆𝐻𝑓𝑜 )𝐷 + (∆𝐻𝑓𝑜 )𝐸 − (∆𝐻𝑓𝑜 )𝐴 𝑜 ∆𝐻𝑟,2 = −74.85 + 52.28 − (−103.8) = 81.23

𝑘𝐽 𝐽 = 81230000 𝑚𝑜𝑙 𝑘𝑚𝑜𝑙

𝑇 𝑜 [∆𝐻𝑅𝑋𝑁 (𝑇)]2 = ∆𝐻𝑟,2 + ∫ 𝐶𝑝𝐷 + 𝐶𝑝𝐸 − 𝐶𝑝𝐴 𝑑𝑇 298

Reaction (3): 𝑜 ∆𝐻𝑟,3 = (∆𝐻𝑓𝑜 )𝐹 − ((∆𝐻𝑓𝑜 )𝐸 + (∆𝐻𝑓𝑜 )𝐶 ) 𝑜 ∆𝐻𝑟,3 = −84.67 − (52.28 + 0) = −136.95

𝑘𝐽 𝐽 = −136950000 𝑚𝑜𝑙 𝑘𝑚𝑜𝑙

𝑇 𝑜 [∆𝐻𝑅𝑋𝑁 (𝑇)]3 = ∆𝐻𝑟,3 + ∫ 𝐶𝑝𝐹 − 𝐶𝑝𝐸 − 𝐶𝑝𝐶 𝑑𝑇 298

126

For solving the equations simultaneously, polymath software was used. However, polymath code is given below:

Figure 106: Polymath code.

127

Figure 107: Polymath code.

128

After solving mole balance, energy balance, and the differential equation, the software exhibits the volume of catalyst needed to achieve 40% of single pass conversion, flow rates profile, and temperature profile.

Figure 108: Temperature profile of the reactor (K) vs Volume of the catalyst (m3)

129

Figure 109: Flowrates profile (kmol/s) vs Volume of catalyst (m3).

130

Figure 110: Single pass conversion of propane vs volume of the catalyst

As shown in Figure 110, once the curve reached around 10.5 m3 the conversion change start to decrease and reach plateau. However, this phenomenon happens due to the conversion of propane, in this case the conversion is controlled by equilibrium constant.

131

So far, the calculated volume using polymath is the catalyst volume in the reactor tube. In our case, four identical plug flow reactors in series are used to convert Propane to Propylene. Therefore,

𝑉𝑇𝑜𝑡𝑎𝑙 = 𝑉1 + 𝑉2 + 𝑉3 + 𝑉4 𝑉𝑇𝑜𝑡𝑎𝑙 = 4 ∗ 𝑉𝑖 Where 𝑖 = 1,2,3, 𝑎𝑛𝑑 4 𝑉𝑖 = 𝑉𝑖 =

𝑉𝑇𝑜𝑡𝑎𝑙 4

10.5 = 2.625 𝑚3 4

However, the calculation of reactor volume will be conducted using heuristics. Moreover, the reactor length to diameter ratio will be between [3-4] for plug flow reactor.

𝐿 =3 𝑑

𝐿 =3∗𝑑

Therefore, to calculate the volume of each reactor:

𝑉𝑖 =

𝜋 ∗ 3 ∗ 𝑑 3 = 2.625 𝑚3 4 𝑑 = 1.036 𝑚 𝐿 = 3.108

Where, Vi: volume of each reactor (m3) L: length of the reactor (m)

132

Thus, each plug flow reactor for propylene production has a volume of 2.625 m3, length of 3.108 m, and diameter of 1.036 m.

Generally, most plug flow reactors are covered from the top and the bottom. Moreover, the cover called hemispheres, and they are introduced for safety factors. Further calculations will be conducted to determine volume of hemispheres.

𝑉ℎ𝑒𝑚𝑖𝑠𝑝ℎ𝑒𝑟𝑒 =

2𝜋 3 ∗𝑟 3

However, 𝑟=

𝑑 2

𝑉ℎ𝑒𝑚𝑖𝑠𝑝ℎ𝑒𝑟𝑒 =

=

1.036 2

= 0.518 𝑚,

2𝜋 ∗ 0.5183 = 0.2911 𝑚3 3

𝑉𝑇𝑜𝑡𝑎𝑙 = 𝑉𝑖 + 2𝑉ℎ𝑒𝑚𝑖𝑠𝑝ℎ𝑒𝑟𝑒 = 3.2072 𝑚3

𝐿𝑇𝑜𝑡𝑎𝑙 = 𝐿𝑖 + 2ℎℎ𝑒𝑚𝑖𝑠𝑝ℎ𝑒𝑟𝑒 = 3.108 + 2 ∗ 0.518 = 4.144 𝑚

Table 66: comparison between calculated and simulated parameters

Parameter 𝑇(𝐶 𝑜 ) Length (m) Diameter (m)

Calculated 483.88 4.144 1.036

Simulated 556.7 3.5 1

Error % 13.08 18.4 3.6

133

Safety factors such as material of construction should be taken into consider by evaluation our operating conditions. The process operated at 3 bar and a temperature range of [650-700] Celsius. In our case, the selection of material of construction should be further focused on handling high temperature conditions.

Figure 111: maximum allowable stress VS Temperature for different grades

From Figure 111, several grades are reliable under our conditions such as Grade 304 and 316 stainless steel. But our choice will go with grade 316 stainless steel since it exhibits more allowable stress than grade 304.

134

Continuing in safety factors selections and calculations, wall thickness of the tube is measured after material of construction selection. However, a semi-empirical relation is used to determine wall thickness of the tube. 𝑡=

𝑃𝐷 + 𝐶𝐴 2𝑆𝐸 − 1.2𝑃

Where, t: Tube thickness (in).

P: Operating pressure (psi).

D: Tube diameter (in).

S: Allowable stress (psi).

E: Quality factor of longitudinal-joint.

CA: Corrosion allowance (in).

Thus, P = 3 bar = 43.51 psi D = 1.036 m = 40.787 in S = 250 bar = 3625.94 psi E=1 CA = [ 0.0118-0.1181] inches for stainless steel, the average equals 0.065

𝑡=

(43.51)(40.787) + 0.065 = 0.3095 𝑖𝑛 = 7.85 𝑚𝑚 2(3625.94 ∗ 1) − 1.2(43.51)

References • •

Fogler, H. S. (2020). Elements of chemical reaction engineering. Pearson. Turton, R., Bailie, R. C., Whiting, W. B., & Shaeiwitz, J. A. (2009). Analysis, synthesis and design of Chemical Processes. Prentice Hall.

135

4.2

T-101, and T-103 Design

By: Asim Algarni

136

Introduction Separation process plays an essential role in chemical industries. For example, Separation of two or more components are being separated using separation process. Moreover, purity incensement is being also done through separation process (mainly in distillation column). In Propane dehydrogenation process (PDH), three distillation columns and one flash drum are to be used to provide desired product, which is propylene, of purity of 99.5%. In this report, design parameters of T-101, and T-103 such as diameter of both enriching and rectifying sections, and total height of the columns will be provided.

Depropanizer (T-101) Depropanizer (T-101) is the first distillation column in Propane Dehydrogenation Process (PDH). It uses liquefied petroleum gas (LPG) as a fresh feed to separate Propane form n-Butane, and Iso-Butane. Propane enters T-101 of composition equal to 0.6373, where n-Butane, and IsoButane compositions are 0.18135 and 0.18135 respectively.

For Depropanizer (T-101), there are some assumption that are used to solve the system which are: 1.

2.

3.

4.

5.

Feed to column is saturated vapor.

Constant molar overflow (CMO).

Vapor and liquid are in equilibrium in each stage.

Total reflux.

Constant pressure at each tray. 𝐹 = 𝐷 + 𝐵 𝑧𝐹 𝐹 = 𝑥𝐷 𝐷 + 𝑥𝐵 𝐵

Table 67: Values of feed molar flow rate, and composition of Propane in feed, distillate, and bottom.

F(kmol/h)

ZF

XD

XB

4900

0.6373

0.9924

0.005

137

solving equation 1, and 2 to find values distillate flow rate(D), and bottom flow rate(B). 𝐷 = 4900 − 𝐵 0.6373(4900) = 0.9924(4900 − 𝐵) + 0.005𝐵 F = 4900 kmol/h B = 1528.65 kmol/h D =3371.35 kmol/h

Fenske equation apply two assumptions which are: 1. total reflux 2. stages are in equilibrium state.

(𝐷𝑥𝐴 /𝐷𝑥𝐵 )𝑑𝑖𝑠 ] (𝐵𝑥𝐴 /𝐵𝑥𝐵 )𝑏𝑜𝑡 𝑙𝑛 𝛼𝐴𝐵

𝑙𝑛[ 𝑁𝑚𝑖𝑛 =

According to normal boiling point, it is found that Propane is the light key component (LK), while n-Butane is the heavy key (HK) component, and isobutane is the heavy non-key component (HNK).

Hexane has been used as a reference component in the calculation of relative volatilities; because it accommodates high range of temperature between -98.87 oC and 215.63 oC. Table 68: Light key, heavy key, heavy non-key, and reference.

A (LK)

B (HK)

C (HNK)

Reference

Propane

n-Butane

Isobutane

Hexane

Antoine equation is used to calculate vapor pressure for each component. Vapor pressure calculation will be used to find relative volatilities. 𝑙𝑜𝑔 𝑃 = 𝐴 − ( 𝛼𝐴𝐵 =

𝐵 ) 𝑇+𝐶

𝑃𝐴 𝑃𝐵

138

Where values of A, B, and C are provided for each component.

Table 69: Calculated values for vapor pressure at feed.

Feed

T (°C)

A

B

C

P mmHg

A

46.7376

7.01887

889.864

257.084

12301.7525

B

46.7376

7.00961

1022.48

248.145

3484.94709

𝛼𝐴𝐵(𝑎𝑡 𝑓𝑒𝑒𝑑) =

12301.7525 = 3.5299 3484.94709

Table 70: Calculated values for vapor pressure at distillate.

Distillate

T (°C)

A

B

C

P mmHg

A

22.9154

7.01887

889.864

257.084

6930.70598

B

22.9154

7.00961

1022.48

248.145

1727.67401

𝛼𝐴𝐵(𝑎𝑡 𝑡𝑜𝑝) =

6930.70598 = 4.011 1727.67401

Table 71: Calculated values for vapor pressure at bottom.

Bottom

T (°C)

A

B

C

P mmHg

A

72.1994

7.01887

889.864

257.084

20722.5915

B

72.1994

7.00961

1022.48

248.145

6573.47765

𝛼𝐴𝐵(𝑎𝑡 𝑏𝑜𝑡𝑡𝑜𝑚) =

20722.5915 = 3.152 6573.47765

After finding relative volatilities for feed, distillate, and bottom, the geometric average volatility is to be calculated.

1

𝛼𝐴𝐵 = (𝛼𝐴𝐵(𝑎𝑡 𝑓𝑒𝑒𝑑) 𝛼𝐴𝐵(𝑎𝑡 𝑡𝑜𝑝) 𝛼𝐴𝐵(𝑎𝑡 𝑏𝑜𝑡𝑡𝑜𝑚) )3 Therefore: 1

𝛼𝐴𝐵 = (3.5299 ∗ 4.011 ∗ 3.152)3 = 3.5474

139

Now 𝑁𝑚𝑖𝑛 can be calculated using Fenske equation

(𝐷𝑥𝐴 /𝐷𝑥𝐵 )𝑑𝑖𝑠 ] (𝐵𝑥𝐴 /𝐵𝑥𝐵 )𝑏𝑜𝑡 𝑙𝑛 𝛼𝐴𝐵

𝑙𝑛[ 𝑁𝑚𝑖𝑛 =

𝑁𝑚𝑖𝑛

0.9924 𝑙𝑛[ 0.0002 ] 0.005 0.4980 = = 10.354 𝑙𝑛 (3.5474)

𝑐

𝐹(1 − 𝑞) = ∑ 𝑖=1

𝛼𝑖−𝑟𝑒𝑓 𝐹𝑍𝑖 𝛼𝑖−𝑟𝑒𝑓 − ∅

It is required first to find 𝛼𝑖−𝑟𝑒𝑓 for each component to the reference which is Hexane.

Table 72: Calculated values for vapor pressure for Hexane and isobutane at feed.

Feed

T (°C)

A

B

C

P mmHg

Ref

46.7376

7.07893

1274.64

243.362

484.315868

C

46.7376

6.93388

953.92

247.077

4866.38828

Table 73: relative volatilities for each component to the reference.

αA-ref 25.4

αB-ref 7.196

αC-ref 10.05

Since the feed is saturated vapor, quality value (q) is equal to zero. So, substitute all values in Underwood equation to find value of ∅.

𝐹(1 − 𝑞) =

𝛼𝐴−𝑟𝑒𝑓 𝐹𝑍𝐴 𝛼𝐴−𝑟𝑒𝑓 −∅

𝛼

𝐹𝑍𝐵

+ 𝛼𝐵−𝑟𝑒𝑓 −∅ + 𝐵−𝑟𝑒𝑓

𝛼𝐶−𝑟𝑒𝑓 𝐹𝑍𝐶 𝛼𝐶−𝑟𝑒𝑓 −∅

140

𝑞=

𝑙𝑖𝑞𝑢𝑖𝑑 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑏𝑒𝑙𝑜𝑤 𝑓𝑒𝑒𝑑 𝑠𝑡𝑎𝑔𝑒 − 𝑙𝑖𝑞𝑢𝑖𝑑 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑎𝑏𝑜𝑣𝑒 𝑓𝑒𝑒𝑑 𝑠𝑡𝑎𝑔𝑒 𝑓𝑒𝑒𝑑 𝑟𝑎𝑡𝑒 𝑞=

4900(1 − 0.433) =

8386 − 6266 = 0.433 4900

25.4 ∗ 4900 ∗ 0.6373 7.196 ∗ 4900 ∗ 0.18135 10.048 ∗ 4900 ∗ 0.18135 + + 25.4 − ∅ 7.196 − ∅ 10.048 − ∅

Solve Underwood equation to find values of ∅. 𝛼𝐻𝐾−𝑟𝑒𝑓 < ∅ < 𝛼𝐿𝐾−𝑟𝑒𝑓 7.33< ∅ <25.43

∅1 = -12.8995 (Rejected) ∅2 = 8.16849 (Accepted) ∅3 =13.3105 (Accepted)

The value of 13.3105 will be used in the calculation for Vmin.

𝑐

𝑉𝑚𝑖𝑛 = ∑ 𝑖=1

𝑉𝑚𝑖𝑛 =

𝑉𝑚𝑖𝑛 =

𝛼𝐴−𝑟𝑒𝑓 𝐷𝑥𝐴,𝑑𝑖𝑠𝑡 𝛼𝐴−𝑟𝑒𝑓 −∅

25.4∗0.9924∗3371.35 25.4−13.3105

+

+

𝛼𝑖−𝑟𝑒𝑓 𝐷𝑥𝑖,𝑑𝑖𝑠𝑡 𝛼𝑖−𝑟𝑒𝑓 − ∅

𝛼𝐵−𝑟𝑒𝑓 𝐷𝑥𝐵,𝑑𝑖𝑠𝑡 𝛼𝐵−𝑟𝑒𝑓 −∅

+

7.196∗0.0002∗3371.35 7.196−13.3105

𝑉𝑚𝑖𝑛 = 6978.73

𝛼𝐶−𝑟𝑒𝑓 𝐷𝑥𝐶,𝑑𝑖𝑠𝑡

+

𝛼𝐶−𝑟𝑒𝑓 −∅

10.048∗0.0048∗3371.35 10.048−13.3105

𝑘𝑚𝑜𝑙 ℎ

𝐿𝑚𝑖𝑛 = 𝑉𝑚𝑖𝑛 − 𝐷

141

𝐿𝑚𝑖𝑛 = 6978.73 − 3371.35 = 3607.38

𝑅𝑚𝑖𝑛 =

𝑘𝑚𝑜𝑙 ℎ

𝐿𝑚𝑖𝑛 3607.38 = = 1.07 𝐷 3371.35

From heuristics, it is stated that the optimum reflux ratio is between 1.2 to 1.5 times the minimum reflux ratio. An average value of 1.35 will be used. Therefore, 𝑅𝑜𝑝𝑡𝑖𝑚𝑢𝑚 = 1.35 ∗ 𝑅𝑚𝑖𝑛 = 1.35 ∗ 1.07 = 1.4445

Figure 112: Gilliland correlation curve.

𝐿 𝐿 𝐷 − (𝐷)𝑚𝑖𝑛 = 𝑅 − 𝑅𝑚𝑖𝑛 = 1.4445 − 1.07 = 0.15 𝐿 𝑅+1 1.4445 + 1 𝐷+1

142

Figure 113: Corresponded value for (R-Rmin/R+1).

𝑁 − 𝑁𝑚𝑖𝑛 𝑁 − 9.186 = 0.46 = 𝑁+1 𝑁+1 Solve the above equation for N to calculate number of theoretical stages (N) N = 17.863

Modified Fenske equation is used to find minimum number of feed stage. 𝑁𝐹,𝑚𝑖𝑛 can be calculated using the given formula:

𝑁𝐹,𝑚𝑖𝑛

𝑁𝐹,𝑚𝑖𝑛

𝑥 (𝑥 𝐿𝐾 )𝑑𝑖𝑠𝑡 𝑙𝑛[ 𝐻𝐾 ] 𝑧 (𝑧 𝐿𝐾 ) 𝐻𝐾 = 𝑙𝑛 𝛼𝐿𝐾−𝐻𝐾

0.9924 𝑙𝑛[ 0.0002 0.6373 ] ( ) 0.18135 = 3.909 = 𝑙𝑛 3.5474

143

After determining 𝑁𝐹,𝑚𝑖𝑛 , the value of theoretical feed stage can be determined using the following formula:

𝑁𝐹,𝑚𝑖𝑛 𝑁𝐹 = 𝑁𝑚𝑖𝑛 𝑁 𝑁𝐹 =

𝑁 ∗ 𝑁𝐹,𝑚𝑖𝑛 17.863 ∗ 3.909 = = 6.7439 𝑁𝑚𝑖𝑛 10.354

According to Turton, R., Bailie, R. C., etc., the efficiency of tray towers that contains light hydrocarbons is in the range of 60% to 90%. Therefore, an efficiency of 75% is assumed to calculate number of actual trays for Depropanizer (T-101). 𝑁𝐴𝑐𝑡𝑢𝑎𝑙 =

17.863 0.75

= 23.82

Therefore, T-101 has 24 trays.

To calculate column diameter, multiple steps is to done. It is required to find all the following values to find column diameter.

1. vapor velocity Flv 2. Capacity factor Csb,f 3. Flooding velocity uflood 4. operating velocity uop 5. column diameter Dia Table 74: Required Parameters for diameter calculation.

Property MWL

Top

Bottom

44.15

58.05

MWV

44.12

58

456.3

459.7

ρL (Kg/m ) 3

ρV (Kg/m ) 3

σ (dyne/cm) L (kmol/h) V (kmol/h)

35.61 42.18 4.486 3.733 6695.909 9635.909 9884.438 7924.438

144

Vapor Velocity Flv vapor velocity is given by the following formula:

𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 𝑄𝑙 𝜌𝑙 √ = √ 𝑊𝑣 𝜌𝑙 𝑄𝑣 𝜌𝑣

Where, 𝑊𝑙 : Mass flow rate for liquid phase(kg/h). 𝑊𝑣 : Mass flow rate for liquid phase(kg/h). 𝑄𝑙 : Volumetric Flow for liquid phase (kmol/h). 𝑄𝑣 : Volumetric Flow for vapor phase (kmol/h). 𝜌𝑣 : Mass Density for vapor phase (kg/m3). 𝜌𝑙 : Mass Density for liquid phase (kg/m3).

Therefore,

𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 6695.909 35.61 √ = 0.189 √ = 𝑊𝑣 𝜌𝑙 9884.438 456.3

Capacity factor Csb,f For the design of T-101 it is assumed that the tray spacing is equal to 24-inch. Therefore, the equation to calculate capacity factor as follows: 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 𝐹𝑙𝑣 − 0.22618(𝑙𝑜𝑔10 𝐹𝑙𝑣 )2 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 (0.189) − 0.22618(𝑙𝑜𝑔10 (0.189))2 𝐶𝑠𝑏,𝑓 =0.278288 ft/s

Flooding velocity uflood 𝑢𝑓𝑙𝑜𝑜𝑑 = 𝐶𝑠𝑏,𝑓 (

𝜎 0.2 𝜌𝑙 − 𝜌𝑣 ) √ 20 𝜌𝑣

145

𝑢𝑓𝑙𝑜𝑜𝑑 = 0.278288 (

4.486 0.2 456.3 − 35.61 ) √ = 0.70934 𝑓𝑡/𝑠 = 0.2162𝑚/𝑠 20 35.61

According to Wankat, it is assumed 0.75 for the fraction. Therefore,

Column diameter D ̅​̅​̅​̅​̅𝑉 ) 4𝑉(𝑀𝑉 𝐷𝑖𝑎 = √ 𝜋ƞ𝜌𝑣 (𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛)𝑢𝑓𝑙𝑜𝑜𝑑 (3600)

According to Wankat, it is assumed 0.75 for the fraction and 0.9 for ƞ. Therefore,

4 ∗ 9884.438 ∗ (44.12) 𝐷𝑖𝑎 = √ = 5.4478𝑚 𝜋 ∗ 0.9 ∗ 35.61 ∗ (0.75) ∗ 0.2162 ∗ (3600)

Applying the same procedure to stripping section by calculating all the following values: 1. vapor velocity Flv 2. Capacity factor Csb,f 3. column diameter Dia

Vapor Velocity Flv 𝐹𝑙𝑣 =

𝑄𝑙 𝜌𝑙 9635.909 42.18 √ = 0.36833 √ = 𝑄𝑣 𝜌𝑣 7924.438 549.7

146

Capacity Factor Csb,f 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 𝐹𝑙𝑣 − 0.22618(𝑙𝑜𝑔10 𝐹𝑙𝑣 )2 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 (0.36833) − 0.22618(𝑙𝑜𝑔10 (0.36833))2 𝐶𝑠𝑏,𝑓 = 0.20751 𝑓𝑡/𝑠

Column Diameter

4 ∗ 7924.438 ∗ (58) 𝐷𝑖𝑎 = √ = 6.336𝑚 𝜋 ∗ 0.9 ∗ 42.18 ∗ (0.75) ∗ 0.1422 ∗ (3600)

According to Wankat, it is assumed 24-inch of tray spacing. Therefore, column height can be found using the following formula.

𝐻 = 𝑁𝑎𝑐𝑡𝑢𝑎𝑙 ∗ 𝑇𝑟𝑎𝑦 𝑠𝑝𝑎𝑐𝑖𝑛𝑔 = 23.82 ∗ 0.6096 = 14.521𝑚

147

Propane/Propylene splitter (T-103)

Propane/Propylene splitter (T-103) is the last distillation column in the process. The main purpose of T-103 is to ensure a purity of 99.5% of Propylene.

For Propane/Propylene splitter (T-103), there are some assumption that are used to solve the system which are: 1.

2.

3.

4.

Constant molar overflow (CMO).

Vapor and liquid are in equilibrium in each stage.

Total reflux.

Constant pressure at each tray.

𝐹 = 𝐷 + 𝐵 𝑧𝐹 𝐹 = 𝑥𝐷 𝐷 + 𝑥𝐵 𝐵

Table 75: values of feed molar flow rate, and composition of Propane in feed, distillate, and bottom.

F(kmol/h)

ZF

XD

XB

2937

0.3709

0.995

0.005

solving equation 1, and 2 to find values distillate flow rate(D), and bottom flow rate(B). 𝐷 = 2933 − 𝐵 0.3709(2937) = 0.995(2937 − 𝐵) + 0.005𝐵 F=2937 kmol/h B = 1851.5 kmol/h D = 1085.5 kmol/h

148

Fenske equation apply two assumptions which are: 1. total reflux 2. stages are in equilibrium state.

(𝐷𝑥𝐴 /𝐷𝑥𝐵 )𝑑𝑖𝑠 ] (𝐵𝑥𝐴 /𝐵𝑥𝐵 )𝑏𝑜𝑡 𝑙𝑛 𝛼𝐴𝐵

𝑙𝑛[ 𝑁𝑚𝑖𝑛 =

According to normal boiling point, it is found that Propylene is the light key component (LK), while Propane is the heavy key component.

Hexane has been used as a reference component in the calculation of relative volatilities; because it accommodates high range of temperature between -98.87 oC and 215.63 oC.

Table 76: Light key, heavy key, and reference.

A (LK)

B (HK)

Reference

Propylene

Propane

Hexane

Antoine equation is used to calculate vapor pressure for each component. Vapor pressure calculation will be used to find relative volatilities. 𝑙𝑜𝑔 𝑃 = 𝐴 − ( 𝛼𝐴𝐵 =

𝐵 ) 𝑇+𝐶

𝑃𝐴 𝑃𝐵

Where values of A, B, and C are provided for each component.

Table 77: Calculated values for vapor pressure at feed.

Feed

T (°C)

A

B

C

P mmHg

A

53.38

7.01672

860.992

255.8895 17090.9498

B

53.38

7.01887

889.864

257.084

14211.2108

149

𝛼𝐴𝐵(𝑎𝑡 𝑓𝑒𝑒𝑑) =

17090.9498 = 1.203 14211.2108

Table 78: Calculated values for vapor pressure at top.

Top

T (°C)

A

B

C

P mmHg

A

45.18

7.01672

860.992

255.8895

14352.97

B

45.18

7.01887

889.864

257.084

11881.5753

𝛼𝐴𝐵(𝑎𝑡 𝑡𝑜𝑝) =

14352.97 = 1.208 11881.5753

Table 79: Calculated values for vapor pressure at bottom.

Bottom

T (°C)

A

B

C

P mmHg

A

57.24

7.01672

860.992

255.8895 18496.2832

B

57.24

7.01887

889.864

257.084

15410.9502

18496.2832 = 1.20 15410.9502

𝛼𝐴𝐵(𝑎𝑡 𝑏𝑜𝑡𝑡𝑜𝑚) =

After finding relative volatilities for feed, distillate, and bottom, the geometric average volatility is to be calculated.

1

𝛼𝐴𝐵 = (𝛼𝐴𝐵(𝑎𝑡 𝑓𝑒𝑒𝑑) 𝛼𝐴𝐵(𝑎𝑡 𝑡𝑜𝑝) 𝛼𝐴𝐵(𝑎𝑡 𝑏𝑜𝑡𝑡𝑜𝑚) )3 Therefore: 1

𝛼𝐴𝐵 = (1.203 ∗ 1.208 ∗ 1.2)3 = 1.204

Now 𝑁𝑚𝑖𝑛 can be calculated using Fenske equation

(𝐷𝑥𝐴 /𝐷𝑥𝐵 )𝑑𝑖𝑠 ] (𝐵𝑥𝐴 /𝐵𝑥𝐵 )𝑏𝑜𝑡 𝑙𝑛 𝛼𝐴𝐵

𝑙𝑛[ 𝑁𝑚𝑖𝑛 =

150

𝑁𝑚𝑖𝑛

0.995 𝑙𝑛[ 0.005 ] 0.005 0.9867 = = 56.98 𝑙𝑛 (1.204)

𝑐

𝐹(1 − 𝑞) = ∑ 𝑖=1

𝛼𝑖−𝑟𝑒𝑓 𝐹𝑍𝑖 𝛼𝑖−𝑟𝑒𝑓 − ∅

It is required first to find 𝛼𝑖−𝑟𝑒𝑓 for each component to the reference which is Hexane.

Table 80: Calculated values for vapor pressure for Hexane at feed.

Feed

T (°C)

A

B

C

P mmHg

Ref

53.38

7.07893

1274.64

243.362

607.409288

Table 81: relative volatilities for each component to the reference.

αA-Ref

αB-Ref

28.137

23.396

Since feed is not either saturated liquid or saturated gas, quality value (q) can be calculated using the following formula: 𝑞=

𝑙𝑖𝑞𝑢𝑖𝑑 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑏𝑒𝑙𝑜𝑤 𝑓𝑒𝑒𝑑 𝑠𝑡𝑎𝑔𝑒 − 𝑙𝑖𝑞𝑢𝑖𝑑 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑎𝑏𝑜𝑣𝑒 𝑓𝑒𝑒𝑑 𝑠𝑡𝑎𝑔𝑒 𝑓𝑒𝑒𝑑 𝑟𝑎𝑡𝑒

Therefore, 𝑞=

34648.893 − 32286.655 = 0.81 2937

So, by founding quality value for the feed, Underwood equation is used to find value of ∅.

𝐹(1 − 𝑞) =

𝛼𝐴−𝑟𝑒𝑓 𝐹𝑍𝐴 𝛼𝐴−𝑟𝑒𝑓 −∅

𝛼

𝐹𝑍𝐵

+ 𝛼𝐵−𝑟𝑒𝑓 −∅ 𝐵−𝑟𝑒𝑓

151

2937(1 − 0.81) =

28.137 ∗ 2937 ∗ 0.3709 23.396 ∗ 2937 ∗ 0.6291 + 28.137 − ∅ 23.396 − ∅

Solve Underwood equation to find values of ∅. 𝛼𝐻𝐾−𝑟𝑒𝑓 < ∅ < 𝛼𝐿𝐾−𝑟𝑒𝑓 23.911< ∅ <28.784 ∅1 = −107.07 (Rejected) ∅2 = 26.211 (Accepted)

𝑐

𝑉𝑚𝑖𝑛 = ∑ 𝑖=1

𝑉𝑚𝑖𝑛 =

Vmin =

𝛼𝑖−𝑟𝑒𝑓 𝐷𝑥𝑖,𝑑𝑖𝑠𝑡 𝛼𝑖−𝑟𝑒𝑓 − ∅

𝛼𝐴−𝑟𝑒𝑓 𝐷𝑥𝐴,𝑑𝑖𝑠𝑡 𝛼𝐴−𝑟𝑒𝑓 −∅

28.137∗1085.5∗0.995 28.137−26.211

+

+

𝛼𝐵−𝑟𝑒𝑓 𝐷𝑥𝐵,𝑑𝑖𝑠𝑡 𝛼𝐵−𝑟𝑒𝑓 −∅

23.396∗1085.5∗0.005

𝑉𝑚𝑖𝑛 = 15733.707

23.396−26.211

𝑘𝑚𝑜𝑙 ℎ

𝐿𝑚𝑖𝑛 = 𝑉𝑚𝑖𝑛 − 𝐷 𝐿𝑚𝑖𝑛 = 15733.707 − 1085.5 = 14647.907

𝑅𝑚𝑖𝑛 =

𝑘𝑚𝑜𝑙 ℎ

𝐿𝑚𝑖𝑛 14647.907 = = 13.494 𝐷 1085.5

According to heuristics, it is stated that the optimum reflux ratio is between 1.2 to 1.5 times the minimum reflux ratio. An average value of 1.35 will be used. Therefore, 𝑅𝑜𝑝𝑡𝑖𝑚𝑢𝑚 = 1.35 ∗ 𝑅𝑚𝑖𝑛 = 1.35 ∗ 13.494 = 18.217

152

Figure 114: Gilliland correlation curve.

𝐿 𝐿 𝐷 − (𝐷)𝑚𝑖𝑛 = 𝑅 − 𝑅𝑚𝑖𝑛 = 18.217 − 13.494 = 0.2458 𝐿 𝑅+1 18.217 + 1 𝐷+1

Figure 115: Corresponded value for (R-Rmin/R+1).

153

𝑁 − 𝑁𝑚𝑖𝑛 𝑁 − 56.98 = 0.4 = 𝑁+1 𝑁+1 Solve the above equation for N to calculate number of theoretical stages (N) N = 95.6333 𝑁𝐴𝑐𝑡𝑢𝑎𝑙 =

95.6333 = 144.89 0.66

Therefore, 𝑁𝐴𝑐𝑡𝑢𝑎𝑙 is equal to 145 trays.

Modified Fenske equation is used to find minimum number of feed stage. 𝑁𝐹,𝑚𝑖𝑛 can be calculated using the given formula:

𝑁𝐹,𝑚𝑖𝑛

𝑁𝐹,𝑚𝑖𝑛

𝑥 (𝑥 𝐿𝐾 )𝑑𝑖𝑠𝑡 𝑙𝑛[ 𝐻𝐾 ] 𝑧 (𝑧 𝐿𝐾 ) 𝐻𝐾 = 𝑙𝑛 𝛼𝐿𝐾−𝐻𝐾

0.995 0.005 ] 𝑙𝑛[ 0.3709 (0.6238) = = 31.3128 𝑙𝑛 1.204

After determining 𝑁𝐹,𝑚𝑖𝑛 , the value of theoretical feed stage can be determined using the following formula: 𝑁𝐹,𝑚𝑖𝑛 𝑁𝐹 = 𝑁𝑚𝑖𝑛 𝑁 𝑁𝐹 =

𝑁 ∗ 𝑁𝐹,𝑚𝑖𝑛 95.6333 ∗ 31.3128 = = 52.55 𝑁𝑚𝑖𝑛 56.98

154

To calculate column diameter, multiple steps is to done. It is required to find all the following values to find column diameter.

1. vapor velocity Flv 2. Capacity factor Csb,f 3. Flooding velocity uflood 4. operating velocity uop 5. column diameter Dia

Table 82: Required Parameters for diameter calculation.

Property MWL

Top 42.09

Bottom 44.09

MWV

42.09

44.09

ρL (Kg/m3)

461.9

435

ρV (Kg/m3)

44.48

46.67

σ (dyne/cm) L (kmol/h) V (kmol/h)

3.917 26052.08 27137.58

3.355 26095.1 24243.6

Vapor Velocity Flv vapor velocity is given by the following formula:

𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 𝑄𝑙 𝜌𝑙 √ = √ 𝑊𝑣 𝜌𝑙 𝑄𝑣 𝜌𝑣

Where, 𝑊𝑙 : Mass flow rate for liquid phase(kg/h). 𝑊𝑣 : Mass flow rate for liquid phase(kg/h). 𝑄𝑙 : Volumetric Flow for liquid phase (kmol/h). 𝑄𝑣 : Volumetric Flow for vapor phase (kmol/h).

155

𝜌𝑣 : Mass Density for vapor phase (kg/m3). 𝜌𝑙 : Mass Density for liquid phase (kg/m3).

Therefore,

𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 26052.08 44.48 √ = 0.298 √ = 𝑊𝑣 𝜌𝑙 27134.583 461.3

Capacity Factor Csb,f For the design of T-101 it is assumed that the tray spacing is equal to 24-inch. Therefore, the equation to calculate capacity factor as follows: 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 𝐹𝑙𝑣 − 0.22618(𝑙𝑜𝑔10 𝐹𝑙𝑣 )2 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 (0.298) − 0.22618(𝑙𝑜𝑔10 (0.298))2 𝐶𝑠𝑏,𝑓 =0.23

Flooding Velocity Uflood

𝑢𝑓𝑙𝑜𝑜𝑑 = 𝐶𝑠𝑏,𝑓 (

𝑢𝑓𝑙𝑜𝑜𝑑 = 0.23(

𝜎 0.2 𝜌𝑙 − 𝜌𝑣 ) √ 20 𝜌𝑣

3.917 0.2 461.9 − 44.48 ) √ = 0.509 𝑓𝑡/𝑠 = 0.155𝑚/𝑠 20 44.48

156

Column Diameter Dia

̅​̅​̅​̅​̅𝑉 ) 4𝑉(𝑀𝑉 𝐷𝑖𝑎 = √ 𝜋ƞ𝜌𝑣 (𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛)𝑢𝑓𝑙𝑜𝑜𝑑 (3600)

According to Wankat, it is assumed 0.75 for the fraction and 0.9 for ƞ. Therefore,

4 ∗ 27137.583 ∗ 42.09 𝐷𝑖𝑎 = √ = 9.3𝑚 𝜋 ∗ 0.9 ∗ 44.48 ∗ 0.75 ∗ 0.155 ∗ 3600

Applying the same procedure to stripping section by calculating all the following values: 1. vapor velocity Flv 2. Capacity factor Csb,f 3. column diameter Dia

Vapor Velocity Flv 𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 26095.099 46.67 √ = 0.35 √ = 𝑊𝑣 𝜌𝑙 24243.603 435

Capacity Factor Csb,f 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 𝐹𝑙𝑣 − 0.22618(𝑙𝑜𝑔10 𝐹𝑙𝑣 )2 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 (0.35) − 0.22618(𝑙𝑜𝑔10 (0.35))2 𝐶𝑠𝑏,𝑓 = 0.212

157

Flooding Velocity Uflood

𝑢𝑓𝑙𝑜𝑜𝑑 = 𝐶𝑠𝑏,𝑓 (

𝑢𝑓𝑙𝑜𝑜𝑑 = 0.212(

𝜎 0.2 𝜌𝑙 − 𝜌𝑣 ) √ 20 𝜌𝑣

3.355 0.2 435 − 46.67 ) √ = 0.428 𝑓𝑡/𝑠 = 0.13𝑚/𝑠 20 46.67

Column Diameter Dia

̅​̅​̅​̅​̅𝑉 ) 4𝑉(𝑀𝑉 𝐷𝑖𝑎 = √ 𝜋ƞ𝜌𝑣 (𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛)𝑢𝑓𝑙𝑜𝑜𝑑 (3600)

𝐷𝑖𝑎 = √

4 ∗ 24243.603 ∗ 44.09 = 9.588𝑚 𝜋 ∗ 0.9 ∗ 46.67 ∗ 0.75 ∗ 0.13 ∗ 3600

According to Wankat, it is assumed 24-inch of tray spacing. Therefore, column height can be found using the following formula.

𝐻 = 𝑁𝑎𝑐𝑡𝑢𝑎𝑙 ∗ 𝑇𝑟𝑎𝑦 𝑠𝑝𝑎𝑐𝑖𝑛𝑔 = 95.6333 ∗ 0.6096 = 58.298𝑚

For the design of distillation column containing hydrocarbons, a proper material of construction should be used. The proper choice of MOC can help in preventing major damages such as pitting, and corrosion. In our case, Carbon Steel is used as a material of construction due to its high resistance to corrosion.

158

References • • •

Turton, R., Bailie, R. C., Whiting, W. B., & Shaeiwitz, J. A. (2009). Analysis, synthesis and design of Chemical Processes. Prentice Hall.

Wankat, P. C. (2007). Separation process engineering. Prentice Hall.

Yaws, C. L. (2003). Yaws' Handbook of thermodynamic and physical properties of chemical compounds physical, thermodynamic and transport properties for 5000 organic chemical compounds. Norwich.

159

4.3

Vessel and T-102 Design

By: Faisal Alasiri

160

Introduction In this chapter the flash drum and the second distillation column will be discussed, the separation processes play a crucial role in the industry, there are several equipment used in this regard such as distillation columns, membranes, absorbers, drums, and strippers. The main purpose of the flash drum is to separate hydrogen from the stream to allow an excellent separation of methane and ethylene from propane and propylene in the following distillation column. The flash drum job is to separate vapors from liquids in a liquid-vapor mixture. Distillation column job is to separate the component based in their boiling point. In this process there are three distillation columns and drum.

Flash Drum (V-101) This flash drum purpose is to separate hydrogen form the main stream before entering the second distillation column. Is a very light gas and it can cause us to have a very low temperature in the condenser of the distillation column. To be able to separate the hydrogen the system needs to be pressurized to minimize the losses of propane and propylene, also it needs to be cooled sup -40 °C to liquefy propane and propylene.

Assumptions: -

Isothermal operation.

-

Isobaric operation.

-

75% velocity performance.

-

Vertical positioning since it is gas-liquid separator.

Most values are obtained from Aspen HYSYS for simplicity Feed flow rate = 9546 Ibmol/h.

Vapor fraction = 0.2677.

Vapor flow rate = 0.2677 × 9546 Ibmol/h =2555.46 Ibmol/h.

Liquid flow rate = 9546 Ibmol/h – 2555.46 Ibmol/h =6990.54 Ibmol/h.

161

Table 83: Data collected from Aspen HYSYS.

Flow rate Ibmol/h

Molecular weight Ib/Ibmol

Mass flow rate Ib/h

Density Ib/ft3

Vapor

2555.46

8.055

20584.23

1.42

liquid

6990.54

40.76

284934.41

31.91

To find the diameter and the length of the drum the permeable velocity most be found first using the following equation: 𝑢 = 𝑘√

𝜌𝑙 −1 𝜌𝑣

And k is found by: 𝑘 = 𝑒 𝐴+𝐵𝑙𝑛(𝐹𝑙𝑣)+𝐶(𝑙𝑛(𝐹𝑙𝑣))

2 +𝐷(𝑙𝑛(𝐹𝑙𝑣))3 +𝐸(𝑙𝑛(𝐹𝑙𝑣))4

While Flv is 𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 √ 𝑊𝑣 𝜌𝑙

And A = -1.87748 B = -0.81458 C = -0.18707 D = -0.01452 E = -0.00101

So,

𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 284934.41 1.42 √ = 2.92 √ = 𝑊𝑣 𝜌𝑙 20584.23 31.91

Finding k using the equation, 2 −0.01452(𝑙𝑛(4.53))3 −0.00101(𝑙𝑛(4.53))4

𝑘 = 𝑒 −1.87748−0.81458𝑙𝑛(4.53)−0.18707(𝑙𝑛(4.53))

= 0.0506

162

For the permissible velocity, 𝑢 = 0.0276√

36.38 − 1 = 0.234 𝑓𝑡/𝑠 0.57

To find the diameter known vapor flow rate will be utilized to find the cross-sectional area, 𝑉=

𝑢𝑝𝑒𝑟𝑚 ∗ 3600 ∗ 𝐴𝑐 ∗ 𝜌𝑉 𝑀𝑊𝑉

Solving for the area, 𝐴𝑐 =

𝑉(𝑀𝑊𝑉 ) 2555.464 ∗ 8.055 = = 17.18 𝑓𝑡 2 𝑢𝑝𝑒𝑟𝑚 ∗ 3600 ∗ 𝜌𝑉 0.234 ∗ 3600 ∗ 1.42

For the diameter of the vertical drum, 4 ∗ 17.18 𝐷=√ = 4.68 𝑓𝑡 = 1.43 𝑚. 𝜋 The length is usually taken as L=4D or L= 4.5D so, 𝐿 = 4.68 ∗ (4) = 18.71 𝑓𝑡 = 5.7 𝑚.

Or 𝐿 = 4.684.68 ∗ (4.5) = 21.05 𝑓𝑡 = 6.42 𝑚.

As a comparison the heuristics will be used, -

Heuristic No.3 gas-liquid phase separators are usually vertical.

Heuristic No.9 gas velocity un gas-liquid separators 𝑢 = 𝑘√𝜌𝑙 /𝜌𝑣 − 1 𝑓𝑡/𝑠 k=0.35 for systems with mesh deentrainer, and k=0.0305 without deentrainer.

Heuristic No.12 Good performance can be expected at velocities of 30%–100% of those calculated with the given k; 75% is popular.

H/D should be within 3 to 5.

𝜌𝑙 31.91 𝑢 = 0.75 ∗ 𝑘√ − 1 = 0.75 ∗ 0.0305√ = 0.106 𝑓𝑡/𝑠. 𝜌𝑣 1.42 𝐴𝑐 =

2555.464 ∗ 8.055 = 37.99 𝑓𝑡 2 .

0.106 ∗ 3600 ∗ 1.42

163

4 ∗ 37.99 𝐷=√ = 6.95 𝑓𝑡 = 2.12 𝑚. 𝜋 𝐻1 = 6.95 ∗ (4) = 27.82 𝑓𝑡 = 8.48 𝑚.

Or 𝐻2 = 6.95 ∗ (4.5) = 31.3 𝑓𝑡 = 9.54 𝑚.

Table 84: percentage error of using heuristics.

% Error

u

Ac

D

H4

H4.5

65.80

54.76

32.74

32.74

32.74

Distillation Column (T-102) The goal of the second distillation column is to separate the heavy components in the stream (propane, propylene), form the light components (methane, ethylene), the tower needs to be pressurized to increase the temperature of the condenser otherwise the temperature will be so low it will be hard to liquify the vapor for reflux, the molar composition of the feed stream is propane 0.6168, propylene 0.364, methane 0.0076, ethylene 0.0116.

Assumptions: -

Constant pressure at each tray.

Constant molar overflow (CMO).

Vapor and liquid are in equilibrium in each stage.

All Heavy non-key will go to the bottom while all the light non-key will go to the top.

The fractional recovery of the light key is 0.999.

The fractional recovery of the heavy key is 0.999.

Heuristics Applied: -

relative volatility is the ratio of vapor pressures P1*/P2*, from table 11.13 point 2.

-

Economical optimum reflux ratio is in the range of 1.2 to 1.5 times the minimum reflux ratio, Rmin, from table 11.13 point 5.

-

A safety factor of 10% of the number of trays calculated by the best means is advisable, from table 11.13 point 9.

-

The tray spacing is 24 in, from table 11.14 point 1.

-

Tray Efficiency is 80%, from table 11.14 point 4.

164

Table 85:Light key, heavy key, heavy non-key, light non-key, and the reference.

LK (A) Ethylene

HK (B) HNK (C) propane Propylene

LNK(D) Methane

Reference Hexane

𝐹𝑒𝑒𝑑 = 𝐷𝑖𝑠𝑡𝑖𝑙𝑙𝑎𝑡𝑒 + 𝐵𝑜𝑡𝑡𝑜𝑚 𝑧𝐹 𝐹 = 𝑥𝐷 𝐷 + 𝑥𝐵 𝐵

Mass Balance of Ethylene 0.0116 ∗ 2994 = 𝑥𝐷 𝐷 + 𝑥𝐵 𝐵 Knowing the fractional recovery of ethylene in the distillate we can calculate the amount of ethylene in the distillate and bottom. 𝐷𝐸𝑡ℎ𝑦𝑙𝑒𝑛𝑒 = 0.0116 ∗ 0.999 ∗ 2994 = 34.7 𝑘𝑚𝑜𝑙/ℎ. 𝐵𝐸𝑡ℎ𝑦𝑙𝑒𝑛𝑒 = 0.0116 ∗ 0.001 ∗ 2994 = 0.035 𝑘𝑚𝑜𝑙/ℎ.

Mass Balance of Propane 0.6168 ∗ 2994 = 𝑥𝐷 𝐷 + 𝑥𝐵 𝐵 Knowing the fractional recovery of propane in the bottom we also can calculate the amount of propane in the bottom and distillate. 𝐷𝑃𝑟𝑜𝑝𝑎𝑛𝑒 = 0.6168 ∗ 0.001 ∗ 2994 = 1.85 𝑘𝑚𝑜𝑙/ℎ. 𝐵𝑃𝑟𝑜𝑝𝑎𝑛 = 0.6168 ∗ 0.999 ∗ 2994 = 1844.85 𝑘𝑚𝑜𝑙/ℎ.

Mass Balance of Methane 0.0076 ∗ 2994 = 𝑥𝐷 𝐷 + 0𝐵 Since its assumed that all light non-keys will go to the top so the amount of methane can be easily calculated.

165

𝐷𝑀𝑒𝑡ℎ𝑎𝑛𝑒 = 0.0076 ∗ 2994 = 22.75 𝑘𝑚𝑜𝑙/ℎ.

Mass Balance of Propylene 0.364 ∗ 2994 = 0𝐷 + 𝑥𝐵 𝐵 Since its assumed that all heavy non-keys will go to the bottom so the amount of propylene can be easily calculated. 𝐵𝑃𝑟𝑜𝑝𝑦𝑙𝑒𝑛𝑒 = 0.364 ∗ 2994 = 1089.82 𝑘𝑚𝑜𝑙/ℎ.

According to calculated results the total amount of the distillate and the bottom can be found as follow, 𝐷𝑡𝑜𝑡𝑎𝑙 = ∑ 𝐷𝑖 = 𝐷𝐸𝑡ℎ𝑦𝑙𝑒𝑛𝑒 + 𝐷𝑃𝑟𝑜𝑝𝑎𝑛𝑒 + 𝐷𝑀𝑒𝑡ℎ𝑎𝑛𝑒 = 34.7 + 1.85 + 22.75 = 59.3 𝑘𝑚𝑜𝑙/ℎ. 𝑖

𝐵𝑡𝑜𝑡𝑎𝑙 = ∑ 𝐵𝑖 = 𝐵𝐸𝑡ℎ𝑦𝑙𝑒𝑛𝑒 + 𝐵𝑃𝑟𝑜𝑝𝑎𝑛𝑒 + 𝐵𝑃𝑟𝑜𝑝𝑦𝑙𝑒𝑛𝑒 = 0.035 + 1844.85 + 1089.82 = 2934.705 𝑘𝑚𝑜𝑙/ℎ. 𝑖

Now that the feed, distillate, and the bottom is calculated the mole fraction of the components are calculated and listed in the table below.

Table 86: Components with their feed, distillate, and bottom mol fraction.

Component

Feed mole fraction

Distillate mole fraction

Bottom mole fraction

Propane

0.6168

0.03

0.63

Propylene

0.364

0

0.37

Ethylene

0.0116

0.59

1.18x10-5

Methane

0.0076

0.38

0

Fenske equation is used to find the minimum number of stages to be able to use Fenske equation there are two assumptions needs to be made.

-

Total reflux.

-

Stages are in equilibrium state. (𝐷𝑥𝐴 /𝐷𝑥𝐵 )𝑑𝑖𝑠 ] (𝐵𝑥𝐴 /𝐵𝑥𝐵 )𝑏𝑜𝑡 𝑙𝑛 𝛼𝐴𝐵

𝑙𝑛[ 𝑁𝑚𝑖𝑛 =

166

Also, to use Fenske equation the heavy key and the light key must be stated, and the relative volatility calculated. To do that Antoine equation is used to calculate the vapor pressure to find the volatility.

Antoine equation: 𝑙𝑜𝑔 𝑃 ∗ = 𝐴 − (

𝐵 ) 𝑇+𝐶

Using the vapor pressure: 𝛼𝐴𝐵 =

𝑃𝐴∗ 𝑃𝐵∗

The values of A, B, and C are provided and the key component.

Table 87:Vapor pressure calculation at the feed.

Feed A B

T (°C) -0.1373 -0.1373

A 6.96636 7.01887

𝛼𝐴𝐵 =

B 649.806 889.864

C 262.73 257.084

P* mmHg 31030.05 3594.56

C 262.73 257.084

P* mmHg 11007.21 811.50

C 262.73 257.084

P* mmHg 102940.22 19820.16

31030.05 = 8.63 3594.56

Table 88:Vapor pressure calculation at the top.

Top A B

T (°C) -40.55 -40.55

A 6.96636 7.01887

𝛼𝐴𝐵 =

B 649.806 889.864

11007.21 = 13.56 811.50

Table 89: Vapor pressure calculation at the bottom.

Bottom A B

T (°C) 69.86 69.86

A 6.96636 7.01887

𝛼𝐴𝐵 =

B 649.806 889.864

102940.22 = 5.19 19820.16

167

The relative volatility that going to be used in Fenske equation are the geometric average volatility using the following equation, 1

𝛼𝐴𝐵 = (𝛼𝐴𝐵,𝐹𝑒𝑒𝑑 𝛼𝐴𝐵𝑇𝑜𝑝 𝛼𝐴𝐵𝐵𝑜𝑡𝑡𝑜𝑚 )3 So, 1

𝛼𝐴𝐵 = (8.63 ∗ 13.57 ∗ 5.19)3 = 8.47

(𝐷𝑥𝐴 /𝐷𝑥𝐵 )𝑑𝑖𝑠 ] (𝐵𝑥𝐴 /𝐵𝑥𝐵 )𝑏𝑜𝑡 𝑙𝑛 𝛼𝐴𝐵

𝑙𝑛[ 𝑁𝑚𝑖𝑛 = Substituting in the equation: 𝑙𝑛[ 𝑁𝑚𝑖𝑛 =

(0.59/0.03)𝑑𝑖𝑠 ] (1.18 × 10−5 /0.63)𝑏𝑜𝑡 = 6.49 𝑙𝑛 (8.47)

𝑐

𝐹(1 − 𝑞) = ∑ 𝑖=1

𝛼𝑖−𝑟𝑒𝑓 𝐹𝑍𝑖 𝛼𝑖−𝑟𝑒𝑓 − 𝜑

Underwood equation is used to find the minimum reflux ratio by finding the value of φ. The value of φ is αHK-ref < φ < αLK-ref after that the second underwood equation will be used to find the minimum vapor flow rate. for the sake of simplicity, the reference was chosen to be hexane.

Second Underwood equation: 𝑐

𝑉𝑚𝑖𝑛 = ∑ 𝑖=1

𝛼𝑖−𝑟𝑒𝑓 𝐷𝑥𝑖,𝑑𝑖𝑠𝑡 𝛼𝑖−𝑟𝑒𝑓 − 𝜑

The values needed to be used in the underwood equations: Table 90: relative volatility of each component to the reference.

αA-ref

αB-ref

αC-ref

αD-ref

450.23

52.16

64.85

2518.75

168

Since the feed is fully liquid q=1, 𝑐

𝐹(1 − 𝑞) = ∑ 𝑖=1

2994 ∗ (1 − 1) =

450.23∗2994∗0.0116 450.23−𝜑

+

𝛼𝑖−𝑟𝑒𝑓 𝐹𝑍𝑖 𝛼𝑖−𝑟𝑒𝑓 − 𝜑

52.16∗2994∗0.6168 52.16−𝜑

+

64.85∗2994∗0.364 64.85−𝜑

+

2518.75∗2994∗0.0076 2518.75−𝜑

αHK-ref < φ < αLK-ref , 52.16< φ <450.23 φ1 = 59.46 (accepted). φ2 = 414.73 (accepted). φ3 = 1940.8 (rejected). φ2 will be chosen since it gave the most reasonable Vmin 𝑐

𝑉𝑚𝑖𝑛 = ∑ 𝑖=1

𝛼𝑖−𝑟𝑒𝑓 𝐷𝑥𝑖,𝑑𝑖𝑠𝑡 𝛼𝑖−𝑟𝑒𝑓 − 𝜑

450.23 ∗ 59.3 ∗ 0.59 52.16 ∗ 59.3 ∗ 0.03 2518.75 ∗ 59.3 ∗ 0.38 + + = 470.44 𝐾𝑚𝑜𝑙/ℎ 450.23 − 414.73 52.16 − 414.73 2518.75 − 414.73 𝐿𝑚𝑖𝑛 = 𝑉𝑚𝑖𝑛 − 𝐷 𝐿𝑚𝑖𝑛 = 470.44 − 59.3 = 411.14 𝑘𝑚𝑜𝑙/ℎ. 𝑅𝑚𝑖𝑛 =

𝐿𝑚𝑖𝑛 411.14 = = 6.93 𝐷 59.3

The R optimum according to the heuristics is Rmin (1.2 – 1.5). the average of the two number will be used 1.35. 𝑅𝑜𝑝𝑡𝑖𝑚𝑢𝑚 = 1.35 ∗ 𝑅𝑚𝑖𝑛 = 1.35 ∗ 6.93 = 9.36 After finding the Rmin and R optimum Gilliland correlation will be used to determine the actual number of stages.

169

Figure 116: Gilliland correlation.

Where, 9.36 − 6.93 = 0.23 9.36 − 1 Using the graph: 𝑁 − 𝑁𝑚𝑖𝑛 = 0.41 𝑁+1 Solving the above equation for N to find the actual number of stages, N=11.65 stages and the actual number of stages is NAcutal=11.65/0.8=14.56. which is approximately 15 stages including the reboiler.

The modified Fenske equation is used to find the minimum feed stage N F,min using the following equation:

𝑁𝐹,𝑚𝑖𝑛

𝑥 (𝑥 𝐿𝐾 )𝑑𝑖𝑠𝑡 𝑙𝑛 [ 𝐻𝐾 ] 𝑧 (𝑧 𝐿𝐾 ) 𝐻𝐾 = 𝑙𝑛 𝛼𝐿𝐾−𝐻𝐾

0.59

( )𝑑𝑖𝑠𝑡 𝑙𝑛[ 0.03 0.0116 ]

𝑁𝐹,𝑚𝑖𝑛 =

( ) 0.6168

𝑙𝑛 8.47

= 3.25 which is approximately 4.

170

To finding the minimum feed stage the value of the theoretical fees stage can be calculated using the following relation: 𝑁𝐹,𝑚𝑖𝑛 𝑁𝐹 = 𝑁𝑚𝑖𝑛 𝑁 𝑁𝐹 =

𝑁𝐹.𝑚𝑖𝑛 ∗𝑁 𝑁𝑚𝑖𝑛

=

4∗15 6.49

= 9.2 which can be approximated to be 10

To calculate the column diameter, the following parameters are required Vapor velocity, capacity factor, flooding velocity, and the operating velocity.

Table 91: the parameters required to calculate the diameter.

Required parameters

Top

Bottom

Molecular Weight L (kg/kmol)

26.49

43.42

Molecular Weight v (kg/kmol)

23.28

43.35

Mass Density (kg/m3) L

429.5

407.2

Mass Density (kg/m3) v

41.17

70.78

Surface Tension (dyne/cm)

5.052

3.63

Molar Flow (kmol/h) L

5646

10890

Molar Flow (kmol/h) v

5656

7860

Temperature (K)

232.6

343.01

Vapor Velocity 𝐹𝑙𝑣 =

𝐹𝑙𝑣 =

𝑊𝑙 𝜌𝑣 𝑄𝑙 𝜌𝑙 √ = √ 𝑊𝑣 𝜌𝑙 𝑄𝑣 𝜌𝑣

𝑊𝑙 𝜌𝑣 5656 41.17 √ = 0.31 √ = 𝑊𝑣 𝜌𝑙 5646 429.5

171

Capacity factor Capacity factor can be calculated or read from a graph, using the equation requires a previous knowledge about the spacing between the trays. Since The spacing in the column is assumed to be 24-in, so the equation of the capacity factor will be: 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 𝐹𝑙𝑣 − 0.22618(𝑙𝑜𝑔10 𝐹𝑙𝑣 )2 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 (0.31) − 0.22618(𝑙𝑜𝑔10 (0.31))2 𝐶𝑠𝑏,𝑓 = 0.23 𝑓𝑡/𝑠

Flooding Velocity 𝑢𝑓𝑙𝑜𝑜𝑑 = 𝐶𝑠𝑏,𝑓 (

𝑢𝑓𝑙𝑜𝑜𝑑 = 0.23 (

𝜎 0.2 𝜌𝑙 − 𝜌𝑣 ) √ 20 𝜌𝑣

3.63 0.2 429.5 − 41.17 𝑓𝑡 ) √ = 0.5 = 0.15 𝑚/𝑠 20 41.17 𝑠

Column Diameter

̅​̅​̅​̅​̅𝑉 ) 4𝑉(𝑀𝑉 𝐷𝑖𝑎 = √ 𝜋ƞ𝜌𝑣 (𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛)𝑢𝑓𝑙𝑜𝑜𝑑 (3600) According to Wankat, it is assumed 0.75 for the fraction and ƞ From 0.8 to 0.9 Therefore, it was chosen to be 0.9.

𝐷𝑖𝑎 = √

4 ∗ 5656(23.28) = 3.3 𝑚 𝜋 ∗ 0.9 ∗ 41.17 ∗ (0.75) ∗ 0.15 ∗ (3600)

To find the diameter of the stripping section some parameters are needed to apply a simple and a straightforward equation to find the diameter, the parameters are: -

-

Vapor velocity Flv Capacity factor CSb,f Column Diameter of the rectifying section.

172

The equation used: 𝐷𝑖𝑎𝑡𝑜𝑝 𝑉𝑡𝑜𝑝 0.5 𝑀𝑊𝑣,𝑡𝑜𝑝 0.25 𝜌𝑙,𝑏𝑜𝑡 0.25 𝑇𝑡𝑜𝑝 0.25 𝜎𝑏𝑜𝑡 0.1 𝐶𝑠𝑏,𝑓,𝑏𝑜𝑡 0.5 =( ) ( ) ( ) ( ) ( ) ( ) 𝐷𝑖𝑎𝑏𝑜𝑡𝑡𝑜𝑚 𝑉𝑏𝑜𝑡 𝑀𝑊𝑣,𝑏𝑜𝑡 𝜌𝑙,𝑡𝑜𝑝 𝑇𝑏𝑜𝑡 𝜎𝑡𝑜𝑝 𝐶𝑠𝑏,𝑓,𝑡𝑜𝑝

Vapor Velocity 𝐹𝑙𝑣 =

𝑄𝑙 𝜌𝑣 10890 70.78 √ = 0.58 √ = 𝑄𝑣 𝜌𝑙 7860 407.2

Capacity factor 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 𝐹𝑙𝑣 − 0.22618(𝑙𝑜𝑔10 𝐹𝑙𝑣 )2 𝑙𝑜𝑔10 𝐶𝑠𝑏,𝑓 = −0.94506 − 0.70234𝑙𝑜𝑔10 (0.58) − 0.22618(𝑙𝑜𝑔10 (0.58))2 𝐶𝑠𝑏,𝑓 = 0.16 𝑓𝑡/𝑠

Column Diameter 𝐷𝑖𝑎𝑡𝑜𝑝 5656 0.5 23.28 0.25 407.2 0.25 232.6 0.25 3.63 0.1 0.16 0.5 =( ) ( ) ( ) ( ) ( ) ( ) = 0.9 𝐷𝑖𝑎𝑏𝑜𝑡𝑡𝑜𝑚 7860 43.35 429.5 343.01 5.052 0.23

𝐷𝑖𝑎𝑏𝑜𝑡𝑡𝑜𝑚 =

𝐷𝑖𝑎𝑡𝑜𝑝 3.16 = = 3.7 𝑚 0.9 0.9

According to the assumption that the tray spacing is 24-in, the height will be the product of multiplying the spacing by the actual number of stages. 𝐻 = 𝑡𝑟𝑎𝑦 𝑠𝑝𝑎𝑐𝑖𝑛𝑔 ∗ 𝑁𝑎𝑐𝑢𝑡𝑎𝑙 ∗ 𝑆𝑎𝑓𝑒𝑡𝑦 𝑓𝑎𝑐𝑡𝑜𝑟 = 0.6096 ∗ 15 ∗ 1.1 = 10.06 𝑚

References • • •

Turton, R., Bailie, R. C., Whiting, W. B., & Shaeiwitz, J. A. (2009). Analysis, synthesis and design of Chemical Processes. Prentice Hall.

Wankat, P. C. (2007). Separation process engineering. Prentice Hall.

Yaws, C. L. (2003). Yaws' Handbook of thermodynamic and physical properties of chemical compounds physical, thermodynamic and transport properties for 5000 organic chemical compounds. Norwich.

173

4.4

Heat Exchangers Design

By: Banji Alkhuraim

174

Introduction One of the main and crucial equipment used in most of the chemical plants is the heat exchangers. Heat exchangers are used to manipulate the temperature of the stream by utilizing two different streams, cold and hot streams. Moreover, heat exchangers are used to minimize the cost of the utilities used. There are several types of heat exchanger and the simplest type is double pipe heat exchangers. Also, shell and tube heat exchangers are considered as the most effective one.

Furthermore, the flow inside the heat exchangers is either counter flow or parallel. However, the most effective one is the counter flow. In this report, the type of heat exchanger designed is shell and tube.

There are a set of rules and laws known as standards. These standards are established by a group of experts. Furthermore, the aim of these standards is the assistance in designing a certain equipment in the most efficient way to achieve a specific goal. Hence, the standards in the following table are used in heat exchangers design.

Table 92: The standards used.

Design Heat exchangers Material of construction pipes safety

standard TEMA ASTM ASME WHO

175

Figure 117: Heat Exchanger of a shell and tube type.

In order to design shell and tube heat exchangers, the following steps need to be performed.

1. obtain the following information from Aspen HYSY: -

Tin and Tout for both hot and cold fluids.

Q which is the heat added or removed from the system (positive or negative).

2. Calculate the mass flow rate:

𝑄 = ṁ 𝑐𝑝 ∆𝑇 3. Obtain the value of the overall heat transfer coefficient (U) from the tables listed below:

176

Table93 : Overall heat transfer coefficient.

Table94 : Overall heat transfer coefficient.

177

4. Determine the fouling factor for the shell side and the tube side.

Table95 : Fouling factor for different fluids.

TUBE SIDE 5. Use the following table to select both the outer diameter and the wall thickness.

Table96 : The outside diameter with its corresponding wall thickness.

6. Calculate the tube dimeter using the next equation.

178

𝑑𝑖 = 𝑑𝑜 − 2 ∗ (𝑤𝑎𝑙𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠) 7. Choose the tube length.

8. Calculate the log mean temperature difference (TLMTD).

TLMTD =

(𝑇ℎ,𝑖𝑛 − 𝑇𝑐,𝑜𝑢𝑡 ) − (𝑇ℎ,𝑜𝑢𝑡 − 𝑇𝑐,𝑖𝑛 ) (𝑇ℎ,𝑖𝑛 − 𝑇𝑐,𝑜𝑢𝑡) ln ( ) (𝑇ℎ,𝑜𝑢𝑡 − 𝑇ℎ,𝑜𝑢𝑡)

9. Calculate R and S in order to determine the correction factor from the below equations and figure.

𝑅=

𝑇ℎ,𝑖𝑛 − 𝑇ℎ,𝑜𝑢𝑡 𝑇𝑐,𝑜𝑢𝑡 − 𝑇𝑐,𝑖𝑛

𝑆=

𝑇𝑐,𝑜𝑢𝑡 − 𝑇𝑐,𝑖𝑛 𝑇ℎ,𝑖𝑛 − 𝑇𝑐,𝑖𝑛

Figure118 : Correction factor.

10. Calculate the overall surface area of the heat exchanger.

179

𝐴=

𝑄 𝐹𝑈∆𝑙𝑚𝑡𝑑

11. Calculate the number of tubes needed for the heat exchanger.

𝑁𝑡 =

𝐴 𝜋𝐷0 𝐿

12. Calculate both the mass velocity and the tube velocity.

𝐺𝑡 =

𝑚 𝑁 𝜋 (𝑁𝑡 ) 4 𝐷02 𝑝

𝑢𝑡 =

𝐺𝑡 𝑝𝑡

13. Calculate the Reynold number.

𝑅𝑒 =

𝑝𝑑𝑖 𝑢𝑠 𝜇

14. Calculate Jf (friction factor) using either the equation or the figure.

𝐽𝑓 = 0.4137 𝑅𝑒 −0.2585

180

Figure119 : Friction factor jf.

15. Calculate drop in pressure inside the tube.

𝐿 𝑝𝑢𝑠2 ∆𝑃𝑡 = 𝑁𝑝 [8𝑗𝑓 ( ) + 2.5] 𝐷𝑖 2 16. Calculate Prandtl number.

𝑃𝑟𝑡 =

𝜇𝐶𝑝 𝑘𝑓

17. Calculate the inside film heat transfer coefficient.

-

For turbulent flow:

ℎ𝑖 = 0.023

-

𝐾𝑓 𝑅𝑒 0.8 𝑃𝑟0.33 𝑑𝑖

For laminar flow:

𝐾𝑓 𝐷𝑖 0.33 𝜇 0.14 0.33 ℎ𝑖 = 1.86 (𝑅𝑒𝑃𝑟 ) ( ) ( ) 𝐷𝑖 𝐿 𝜇𝑤

181

Shell Side 1. Determine both the pitch length and the arrangement of the tube.

𝑝𝑡 = 1.25 ∗ 𝐷0

Figure 120: pitch arrangement.

2. Calculate the bundle diameter.

1

𝑁𝑡 𝑛1 𝐷𝑏 = 𝐷0 ( ) 𝐾1 Where the constant K1 and n1 can be found from the table.

182

Table97 :The corresponding values for n1 and K1 for each arrangement.

3. Determine the bundle diameter clearance (BDC).

4. Calculate the shell diameter using both the below equation and figure.

𝐷𝑠 = 𝐷𝑏 + 𝐵𝐷𝐶

Figure121 : The values of the shell diameter for different type of heat exchangers.

5. Assume a value for the baffle spacing.

6. Calculate cross flow area for the shell area.

𝐴𝑠 =

(𝑃𝑡 − 𝐷0 )𝐷𝑠 𝑙𝑏 𝑃𝑡 183

7. Calculate both the mass velocity and velocity of the shell side.

𝐺𝑠 =

𝑚 𝐴𝑠

𝑢𝑠 =

𝐺𝑠 𝑝𝑠

8. Calculate the equivalent diameter for the shell side.

𝑑𝑒 =

1.27 2 (𝑝𝑡 − 0.785𝑑𝑜2 ) 𝑑0

9. Calculate Reynold number.

𝑅𝑒 =

𝐺𝑠 𝑑𝑒 𝜇

10. Find the friction factor from the figure below.

Figure 122: Friction factor jf.

184

11. Calculate drop in pressure inside the shell.

∆𝑃𝑠 = 8𝑗𝑓 (

𝑑𝑠 𝐿 𝜌𝑠 𝑢𝑠 )( ) 𝑑 𝑒 𝑙𝑏 2

12. Calculate Prandtl number of the shell side.

𝑃𝑟𝑠 =

𝜇𝑐𝑝 𝑘𝑓

13. Find the heat transfer factor from the figure below.

Figure 123: Heat transfer factor jh.

14. Calculate Nusselt number. 𝑁𝑢 = 𝑗ℎ 𝑅𝑒𝑃𝑟 0.33 15. Calculate the fluid film coefficient. ℎ𝑜 =

𝑁𝑢 𝑘 𝑑𝑒

185

16. Calculate the overall heat transfer coefficient. 𝑈=

1 𝑑𝑜 𝑑𝑖 ln ( ) 1 1 𝑑𝑖 + 𝑑𝑖 + 𝑑𝑖 + + ℎ𝑖 ℎ𝑑𝑖 2𝑘𝑤 𝑑𝑜 ℎ𝑑𝑜 𝑑𝑜 ℎ𝑜

This sample calculation is done for the unit E-103 and some of the needed data are obtained from Aspen HYSYS. Conditions for stream 20 (hot stream):

𝑇in = 479.46 ℃, 𝑇out = 430.22 ℃, ṁ = 138574.2

𝑘𝑔 ℎ

, Q=2287000

𝐾𝐽 ℎ

.

The mass flow rate for the cold stream can be calculated as the following: 𝑄 = ṁ 𝑐𝑝 ∆𝑇 𝐾𝐽

𝑇in = 66.24 ℃, 𝑇out = 146.2 ℃, Cp=1.903 Kg ℃ 2287000 = ṁ * 1.903 * (146.2– 66.24) ṁ = 15029.85

𝑘𝑔 ℎ

The assumed value of the overall heat transfer coefficient (U) is 50

𝑊 𝑚2 ℃

. Also, the type of the heat

exchanger is floating head.

Tube Side Assume the following: d0 = 0.05 m, di = 0.0436 m, L = 4 m and the wall thickness = 0.0032 m.

Therefore, t1=𝑇h,in = 479.46 ℃ , t2=𝑇h,out = 430.22 ℃ , T1 =𝑇c,in = 66.24 ℃ and T2=𝑇c,out = 146.2 ℃

186

∆𝑇𝐿𝑀𝑇𝐷 =

(𝑇ℎ,𝑖𝑛 − 𝑇𝑐,𝑜𝑢𝑡 ) − (𝑇ℎ,𝑜𝑢𝑡 − 𝑇𝑐,𝑖𝑛 ) (479.46 − 146.2) − (430.22 − 66.24) = = 348.39℃ 479.46 − 146.2 (𝑇ℎ,𝑖𝑛 − 𝑇𝑐,𝑜𝑢𝑡) ln ( 430.22 − 66.24 ) ln ( ) (𝑇ℎ,𝑜𝑢𝑡 − 𝑇ℎ,𝑜𝑢𝑡)

𝑅=

𝑃=

𝑇1 − 𝑇2 66.24 − 146.2 = = 1.62 𝑡2 − 𝑡1 430.22 − 479.46

𝑡2 − 𝑡1 430.22 − 479.46 = = 0.1191 𝑇1 − 𝑇2 66.24 − 479.46

From Figure118 F=0.99 Therefore, the surface area can be calculated using the following equation:

𝐴=

𝑄 635000 = = 36.83 𝑚2 𝐹𝑈∆𝑙𝑚𝑡𝑑 0.99 ∗ 50 ∗ 348.39

𝑁𝑡 =

𝐺𝑡 =

𝐴 36.83 = = 67.23 𝑡𝑢𝑏𝑒𝑠 𝜋𝑑0 𝐿 𝜋 ∗ 0.0436 ∗ 4

𝑚 138574.21 𝑘𝑔 = = 766.93 2 67.23 𝜋 𝑁 𝜋 𝑚 𝑠 (𝑁𝑡 ) 4 𝑑02 ( 2 ) ∗ 4 ∗ 0.04362 ∗ 3600 𝑝

𝑢𝑠 =

𝑅𝑒 =

𝐺𝑡 766.93 𝑚 = = 493.20 𝜌 1.555 𝑠

𝑝𝑑𝑖 𝑢𝑠 1.555 ∗ 0.0436 ∗ 493.20 = = 145257 𝜇 0.0002302

The above Re indicates that the flow is turbulent.

187

𝐽𝑓 = 0.4137 𝑅𝑒 −0.2585 = 0.4137 ∗ 145257−0.2585 = 0.0191

𝐿 𝑝𝑢𝑠2 4 1.555 ∗ 493.202 ∆𝑃𝑡 = 𝑁𝑝 [8𝑗𝑓 ( ) + 2.5] = 2 [8 ∗ 0.0191 ∗ ( ) + 2.5] = 6.263 𝐾𝑝𝑎 𝑑𝑖 2 0.0436 2000 𝑃𝑟𝑡 =

𝜇𝐶𝑝 0.00002302 ∗ 3420 = = 0.6328 𝑘𝑓 0.1244

Then for the turbulent flow: ℎ𝑖 = 0.023 = 0.023

𝐾𝑓 𝑅𝑒 0.8 𝑃𝑟0.33 𝑑𝑖

0.1071 𝑊 145257.03090.8 0.63280.33 = 654.89 2 0.0436 𝑚 𝑐

Shell Side 𝑝𝑡 = 1.25 ∗ 𝑑0 = 1.25 ∗ 0.05 = 0.0625 𝑚 1

1

𝑁𝑡 𝑛 67.23 2.291 𝐷𝑏 = 𝐷0 ( ) = 0.05 ∗ ( ) = 0.706𝑚 𝐾 0.156

From Figure121 , BDC=0.065 m 𝐷𝑠 = 𝐷𝑏 + 𝐷𝐵𝑆 = 0.771 𝑚 𝐴𝑠 =

(𝑃𝑡 − 𝐷0 )𝐷𝑠 𝑙𝑏 (0.0625 − 0.05) ∗ 0.771 ∗ 0.1927 = = 0.0297 𝑚2 𝑃𝑡 0.0625

𝐺𝑠 =

𝑚 15029.848 𝑘𝑔 = = 140.57 2 𝐴𝑠 0.0297 ∗ 3600 𝑚 𝑠

188

𝑢𝑠 =

𝑑𝑒 =

𝐺𝑠 140.57 𝑚 = = 28.50 𝑝𝑠 4.932 𝑠

1.27 2 1.27 (𝑝𝑡 − 0.785𝑑𝑜2 ) = (0.06252 − 0.785 ∗ 0.052 ) = 0.0493 𝑚 𝑑0 0.05 𝑅𝑒 =

𝐺𝑠 𝑑𝑒 140.57 ∗ 0.0493 = = 735133.23 𝜇 0.000009427

From Figure 122, jf =0.038

𝑑𝑠 𝐿 𝜌𝑠 𝑢𝑠 0.771 4 4.932 ∗ 28.50 ∆𝑃𝑠 = 8𝑗𝑓 ( ) ( ) = 8 ∗ 0.038 ( )( )∗ = 6.93 𝑘𝑝𝑎 𝑑𝑒 𝑙𝑏 2 0.0493 0.1927 2000

From Figure 123, jh =0.028 𝑃𝑟𝑠 =

𝜇𝐶𝑝 0.000009427 ∗ 1903 = = 0.804 𝑘𝑓 0.02231

𝑁𝑢 = 𝑗ℎ 𝑅𝑒𝑃𝑟 0.33 = 0.028 ∗ 735133.23 ∗ 0.8040.33 = 19153.96

ℎ𝑜 =

𝑈=

=

𝑁𝑢 𝑘 19153.96 ∗ 0.02231 𝑊 = = 8667.84 2 𝑑𝑒 0.0493 𝑚 𝑐

1 𝑑𝑜 𝑑𝑖 ln ( ) 1 1 𝑑𝑖 + 𝑑𝑖 + 𝑑𝑖 + + ℎ𝑖 ℎ𝑑𝑖 2𝑘𝑤 𝑑𝑜 ℎ𝑑𝑜 𝑑𝑜 ℎ𝑜

1 𝑊 = 45.33 2 0.05 𝑚 𝐶 0.0436 ∗ ln (0.0436) 1 1 0.0436 0.0436 + + + + 654.89 5000 2 ∗ 15 0.05 ∗ 5000 0.05 ∗ 8667.84

𝑈% =

|45.33 − 50| ∗ 100 = 9.37% 50

189

Table 98: E-101 specifications.

Fluid Tin (℃) Tout (℃) Q (kJ /h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-101 Tube side shell side Stream22 Stream2 287.16 44.24 223.84 46.74 -2.34E+05 2.34E+05 138574.2 33618.4 0.0762 0.02052 2.841 2.783 1.85E-05 7.40E-04 2.094 150.5629 208.5338855 0.039481996 0.260661946 0.99 50 31.47138756 897.6924 363.0532 428.6974 2.411306 211564.3 24222.15 0.009584 0.028 3669.173 1317.754 0.689744 10.03616 2338.023 7879.524 4086.177 3274.939 5000 5000 40.563 18.87

Table 99: E-101 Properties.

E-101 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Carbon steel 45 0.05 0.0032 0.0436 4 0.547893759 57.44067542 0.0625 0.65924427 0.058 0.71724427 0.179311068 0.04937125 0.025721967

190

Table 100: E-102 Specifications.

Fluid Tin (℃) Tout (℃) Q (kJ /h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ /kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-102 Tube side shell side Stream21 Stream7 430.22 -13.63 287.16 66.24 -6.08E+05 6.08E+05 13640 3452.46 9.92E-02 2.23E-02 3.284 2.206 2.19E-05 2.23E-05 1.665 15.86 331.3814843 0.558297218 0.322316 0.98 20 26.01542981 1068.918 43.41493 641.9927 2.737385 212419.4 96075.72 0.017362 0.028 10460.27 1575.807 0.726174 2.206 378.1173 1250.688 860.4771 565.1637 5000 5000 30.50157916 52.50789582

Table 101: E-102 Properties.

E-102 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Stainless steel 15 0.05 0.0032 0.0436 4 0.547893759 47.48261756 0.0625 0.606673727 0.058 0.664673727 0.166168432 0.04937125 0.022089558

191

Table 102: E-103 Specifications.

Fluid Tin (℃) Tout (℃) Q (kJ /h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺(kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-103 Tube side shell side Stream20 Stream7 479.46 66.24 430.22 146.2 -2.29E+06 2.29E+06 138574.2 15029.85 1.24E-01 2.23E-02 3.42 1.903 2.3E-05 9.43E-06 1.555 4.932 348.3942988 1.623883022 0.1191617 0.99 50 36.83726899 766.9305 140.4162 493.2029 28.47044 145257 735390.3 0.019155 0.038 6263.261 6916.824 0.632865 0.804105 266.6062 19147.56 654.8973 8652.447 5000 5000 45.42987339 9.140253217

Table 103: E-103 Properties.

E-103 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Stainless steel 15 0.05 0.0032 0.0436 4 0.547893759 67.23432856 0.0625 0.70613851 0.065 0.77113851 0.192784628 0.04937125 0.02973273

192

Table 104: E-104 Specifications.

Fluid Tin (℃) Tout (℃) Q(kJ/h) 𝑚̇ (Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-104 Tube side shell side Stream19 Stream8 534.01 146.2 479.46 226.2 -2.64E+06 2.64E+06 138574.2 14832.51 1.16E-01 1.17E-02 3.56 2.224 2.42E-05 1.17E-05 1.45 3.924 320.3665382 1.466544455 0.140661 0.99 50 46.22581131 1129.102 185.4688 778.6914 47.26524 110156.3 46877.95 0.011346 0.028 15723.85 1121.976 0.743023 2.224 1421.563 1774.509 6981.322 702.0701 5000 5000 55.25381347 10.50762695

Table 105: E-104 Properties.

E-104 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Stainless steel 15 0.03 0.0032 0.0236 4 0.296566346 155.8700502 0.0375 0.611554442 0.055 0.666554442 0.166638611 0.02962275 0.022214741

193

Table 106: E-105 Specifications.

Fluid Tin (℃) Tout (℃) Q(kJ/h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-105 Tube side shell side Stream18 Stream9 593.12 226.2 534.01 306.2 -2.97E+06 2.97E+06 138574.2 14670.48 1.25E-01 4.21E-02 3.7 2.534 2.54E-05 4.21E-05 1.35 3.268 297.2426656 1.353408899 0.1610977 0.99 50 56.1464261 402.5421 82.55854 298.1793 25.26271 690162.6 96932.66 0.012803 0.039 1202.391 3339.047 0.751526 2.534 981.6358 2775.183 2818.826 2363.652 5000 5000 77.09295886 54.18591771

Table 107: E-105 Properties.

E-105 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Stainless steel 15 0.05 0.0032 0.0436 3.2 0.438315007 128.0960615 0.0625 0.935584748 0.058 0.993584748 0.248396187 0.04937125 0.049360533

194

Table 108: E-106 Specifications.

Fluid Tin (℃) Tout (℃) Q(kJ/h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-106 Tube side shell side Stream23 Water 223.84 20 150 30 -2.55E+07 2.55E+07 138574.2 590635.1 6.61E-02 7.07E-04 2.624 4.314 1.66E-05 6.10E-04 2.366 1011 159.8002993 0.135427952 0.362244898 0.99 100 45.66122939 1605.732 1211.766 678.6694 11.98582 162214.6 392304.3 0.010265 0.05 24032.72 1963.517 0.660068 37.22122 1863.22 42558.34 7331.994 1523.596 5000 6000 94.31634316 5.683656844

Table 109: E-106 Properties.

E-106 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Carbon steel 45 0.02 0.0016 0.0168 4 0.211115026 216.2860228 0.025 0.470372089 0.05 0.520372089 0.130093022 0.0197485 0.013539356

195

Table 110: E-107 Specifications.

Fluid Tin (℃) Tout (℃) Q(kJ/h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-107 Tube side shell side Stream25 Water 252.49 20 150 30 -3.67E+05 3.67E+05 138574.2 8.50E+03 7.13E-02 6.88E-01 2.755 4.314 1.77E-05 6.10E-04 11.19 1011 172.1231875 0.097570495 0.440836165 0.99 200 29.90478199 343.248 277.9323 306.7453 2.749083 232316.8 7198.356 0.009355 0.06 28899.12 67553.24 0.685368 3.824913 2514.473 213.8918 14933.88 9314.476 5000 6000 195.756283 2.121858501

Table 111: E-107 Properties.

E-107 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Carbon steel 45 0.016 0.002 0.012 4 0.150796447 198.3122448 0.02 0.362313932 0.05 0.412313932 0.103078483 0.0157988 0.02300139

196

Table 112: E-108 Specifications.

Fluid Tin (℃) Tout (℃) Q(kJ/h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-108 Tube side shell side Stream26 Water 150 20 23.88 30 -3.86E+06 3.86E+06 138574.2 89452.94 4.32E-02 6.33E-01 2.41 4.314 1.47E-05 6.10E-04 14.24 1011 33.8378847 0.079289565 0.970153846 0.91 100 34.81189614 210.6168 224.1651 147.905 2.217261 240868.7 72572.52 0.016807 0.05 10751.46 36323.17 0.820081 4.154626 435.2361 583.337 1118.401 18709.55 5000 6000 76.24414059 23.75585941

Table 113: E-108 Properties.

E-108 Material K (W/m2℃) d0 (m) Wall thickness (m) di (m) L(m) ATube surface (m2) Number of tubes Pt (m) Db (m) BDC (m) Ds (m) Baffle spacing (m) de (m) As (m)

Carbon steel 45 0.02 0.0016 0.0168 4 0.211115026 164.8953973 0.025 0.41784408 0.053 0.47084408 0.11771102 0.0197485 0.011084707

197

Table 114: E-109 Specifications.

Fluid Tin (℃) Tout (℃) Q(KJ/h) 𝑚̇(Kg/h) K (W/m2℃) Cp (kJ/kg ℃) µ (kg/m s) ρ (kg/m3) ∆ TLMTD R P F Uinitial (W/m2℃) A (m2) 𝐺 (kg/s m2) u (m/s) Re jf ∆P (pa) Pr Nu h (W/m2℃) hd (W/m2℃) Ufinal (W/m2℃) Error %

E-109 Tube side shell side Stream29 Freon 119.4 -45 5 -30 6.89E+06 6.89E+06 138574.2 159490.7407 5.57E-02 1.59E-01 2.31 1.08 1.64E-05 2.09E-05 81.57 804 90.80907 0.131188 0.695863 0.97 200 38.49936476 138.1584 273.6789374 16.9374 3.403966884 184996 336180.5285 0.009923 0.048 379.3489 3111.062422 0.681265 0.141828464 2091.472 10168.45604 5296.179 63035.35335 5000 5000 144.0972104 27.95139478

198

Table 115: E-109 Properties.

E-109 Material

Stainless steel

K (W/m ℃) d0 (m) Wall thickness (m)

15

2

di (m) L(m)

0.026 0.002 0.022 3.8

2

ATube surface (m ) Number of tubes Pt (m)

0.262637146

Db (m) BDC (m)

0.515998075 0.053 0.568998075

Ds (m) Baffle spacing (m) de (m) As (m)

146.5876605 0.0325

0.142249519 0.02567305 0.01618794

In this section, the parameters for reboilers and condensers will be tabulated. Also, the methodology used in this section is as same as the methodology used in heat exchangers design section because both reboiler and condenser will be used to exchange heat. Hence, both of them will be considered as shell and tube heat exchangers.

199

Table 116: Specifications of T-101 reboiler.

T-101 REBOILER Tube side shell side Fluid Steam Stream3 Tin (℃) 150 46.74 Tout (℃) 120 72.2 Q(kJ/h) -1.10E+08 1.10E+08 𝑚̇(Kg/h) 1760 2550.474 2 K (W/m ℃) 7.20E-02 7.20E-02 Cp (kJ/kg ℃) 2.918 169.4 µ (kg/m s) 5.65E-02 1.08E-04 ρ (kg/m3) 0.5974 58.53 ∆ TLMTD 75.507253 R 0.848666 P 0.290528 F 0.98 2 Uinitial (W/m ℃) 200 A (m2) 42.23428702 𝐺 (kg/s m2) 8.791625 874.1501 u (m/s) 14.71648 14.93508 Re 4915.346 303422.7 jf 0.045964 0.04 ∆P (pa) 484.01 447.3007 Pr 0.000405 254.3 Nu 156.8591 5767.019 h (W/m2℃) 30000 11067.68 2 hd (W/m ℃) 5000 6000 2 Ufinal (W/m ℃) 155.9257494 Error % 22.03712528 Table 117: Properties of T-101 reboiler.

T-101 REBOILER PROPERTIES Material Carbon steel 2 K (W/m ℃) 15 d0 (m) 0.038 Wall thickness (m) 0.0032 di (m) 0.0316 L(m) 3 2 ATube surface (m ) 0.297822984 Number of tubes 141.8100326 Pt (m) 0.0475 Db (m) 0.743322076 BDC (m) 0.063 Ds (m) 0.806322076 Baffle spacing (m) 0.201580519 de (m) 0.03752215 As (m) 0.032507765

200

Table 118: Specifications of T-102 reboiler.

T-102 REBOILER Tube side shell side Fluid Steam Stream35 Tin (℃) 150 12.22 Tout (℃) 120 69.86 Q(kJ/h) -7.98E+06 7.98E+06 𝑚̇(Kg/h) 127500 817269.9 2 K (W/m ℃) 7.20E-02 1.07E-01 Cp (kJ/kg ℃) 4.503 169.4 µ (kg/m s) 5.65E-02 1.08E-04 ρ (kg/m3) 0.5974 58.53 ∆ TLMTD 93.27848 R 1.921333 P 0.217738 F 0.97 2 Uinitial (W/m ℃) 170 A (m2) 34.30398875 168.5609498 226.2436 𝐺 (kg/s m2) u (m/s) 282.1575992 38.6543 Re 584535.4946 537314 jf 0.013364875 0.038 ∆P (pa) 11566.87229 2143.199 Pr 0.625329815 171.462 Nu 8277.373669 8358.123 h (W/m2℃) 33000 34769.83 2 hd (W/m ℃) 5000 6000 2 Ufinal (W/m ℃) 177.8614057 Error % 4.624356287

201

Table 119: Properties of T-102 reboiler.

T-102 REBOILER PROPERTIES Material Carbon steel K (W/m2℃) 15 d0 (m) 0.026 Wall thickness (m) 0.0032 di (m) 0.0196 L(m) 4 2 ATube surface (m ) 0.246300864 Number of tubes 139.2767698 Pt (m) 0.0325 Db (m) 0.504602985 BDC (m) 0.058 Ds (m) 0.562602985 Baffle spacing (m) 0.140650746 de (m) 0.02567305 As (m) 0.015826106 Table 120: Specifications of T-103 reboiler.

T-103 REBOILER Tube side shell side Fluid Steam Stream39 Tin (℃) 150 53.38 Tout (℃) 120 57.24 Q(kJ/h) -5.41E+06 5.41E+06 81840 432311.66 𝑚̇(Kg/h) K (W/m2℃) 7.20E-02 2.31E-02 Cp (kJ/kg ℃) 4.503 3.242 µ (kg/m s) 5.65E-02 1.08E-04 ρ (kg/m3) 0.5974 152.4 ∆ TLMTD 78.970261 R 0.1286666 P 0.3104947 F 0.99 2 Uinitial (W/m ℃) 170 A (m2) 24.18452956 153.4685476 296.80101 𝐺 (kg/s m2) u (m/s) 256.8941205 19.475132 Re 532198.0772 704883.18 jf 0.013692904 0.039 ∆P (pa) 97994.25856 288.55758 Pr 6.25E-04 15.145212 Nu 767.8961529 4883.1526 h (W/m2℃) 43050 4401.3528 2 hd (W/m ℃) 5000 6000 Ufinal (W/m2℃) 141.8930282 Error % 16.53351284

202

Table 121: Properties of T-103 reboiler.

T-103 REBOILER PROPERTIES Material Carbon steel K (W/m2℃) 15 d0 (m) 0.026 Wall thickness (m) 0.0032 di (m) 0.0196 L(m) 4 2 ATube surface (m ) 0.246300864 Number of tubes 98.19100578 Pt (m) 0.0325 Db (m) 0.433199049 BDC (m) 0.058 Ds (m) 0.491199049 Baffle spacing (m) 0.122799762 de (m) 0.02567305 As (m) 0.012063825 Table 122: Specifications of T-101 condenser.

T-101 CONDENSER Tube side shell side Fluid Stream3 Water Tin (℃) 46.74 20 Tout (℃) 22.92 30 Q(kJ/h) -1.40E+08 1.40E+08 ̇ 𝑚(Kg/h) 240900 324524.8 K (W/m2℃) 2.07E-02 7.07E-04 Cp (kJ/kg ℃) 2.533 4.314 µ (kg/m s) 9.17E-06 6.10E-04 ρ (kg/m3) 58.53 1011 ∆ TLMTD 7.914249173 R 0.419815281 P 0.890800299 F 0.75 2 Uinitial (W/m ℃) 200 A (m2) 32.75854141 𝐺 (kg/s m2) 206.8582 4283.239 u (m/s) 35.34224 42.36636 Re 7.13E+05 2.63E+05 jf 0.007001 0.03 ∆P (pa) 701.0698 2191.724 Pr 1.123368 37.22122 Nu 7259.489 775795.7 2 h (W/m ℃) 4748.533 14617.7 2 hd (W/m ℃) 5000 6000 Ufinal (W/m2℃) 149.0687471 Error % 25.46562647

203

Table 123: Properties of T-101 condenser.

T-101 CONDENSER PROPERTIES Material Carbon steel K (W/m2℃) 45 d0 (m) 0.038 Wall thickness (m) 0.0032 di (m) 0.0316 L(m) 4 2 ATube surface (m ) 0.397097311 Number of tubes 82.49499674 Pt (m) 0.0475 Db (m) 0.586786082 BDC (m) 0.062 Ds (m) 0.648786082 Baffle spacing (m) 0.16219652 de (m) 0.03752215 As (m) 0.021046169 Table 124: Specifications of T-102 condenser.

T-102 CONDENSER Tube side shell side Fluid Stream35 Freon Tin (℃) 12.22 -45 Tout (℃) -40 -30 Q(kJ/h) 5.66E+06 5.66E+06 128900 𝑚̇(Kg/h) 131018.5185 2 K (W/m ℃) 1.07E-01 1.59E-01 Cp (kJ/kg ℃) 2.64 1.08 µ (kg/m s) 9.97E-05 2.09E-05 ρ (kg/m3) 515.3 804 ∆ TLMTD 17.4458708 R 0.28724626 P 0.91261796 F 0.8167 Uinitial (W/m2℃) 200 2 A (m ) 43.3783056 𝐺 (kg/s m2) 2063.564 2086.538955 u (m/s) 4.004587 2.595197705 Re 19875.8 157726.3715 jf 0.017663 0.02 ∆P (pa) 385.5679 1267.866798 Pr 2.463753 0.141828464 Nu 536.5554 5757.803226 h (W/m2℃) 5969.179 58001.51805 2 hd (W/m ℃) 5000 5000 2 Ufinal (W/m ℃) 151.2090717 Error % 24.39546416

204

Table 125: Properties of T-102 condenser.

T-102 CONDENSER PROPERTIES Material Stainless steel 2 K (W/m ℃) 15 d0 (m) 0.016 Wall thickness (m) 0.0032 di (m) 0.0096 L(m) 3 2 ATube surface (m ) 0.090477868 Number of tubes 479.4355389 Pt (m) 0.02 Db (m) 0.53263182 BDC (m) 0.058 Ds (m) 0.59063182 Baffle spacing (m) 0.147657955 de (m) 0.0157988 As (m) 0.017442297 Table 126: Specifications of T-103 condenser.

T-103 CONDENSER Tube side shell side Fluid Stream39 Water Tin (℃) 53.38 20 Tout (℃) 45.18 30 Q(kJ/h) -5.49E+06 5.49E+06 127500 𝑚̇(Kg/h) 127260.1 2 K (W/m ℃) 2.31E-02 7.07E-04 Cp (kJ/kg ℃) 3.242 4.314 µ (kg/m s) 1.04E-05 6.10E-04 ρ (kg/m3) 152.4 1011 ∆ TLMTD 24.26887566 R 1.219512195 P 0.245656081 F 0.98 2 Uinitial (W/m ℃) 200 A (m2) 32.06004412 𝐺 (kg/s m2) 2945.861 3850.714 u (m/s) 19.3298 3.808817 Re 3.40E+05 99732.23 jf 0.008481 0.049 ∆P (pa) 1430.148 764.3516 Pr 1.45848 37.22122 Nu 4370.883 9273.641 h (W/m2℃) 8428.52 414.9976 2 hd (W/m ℃) 5000 6000 2 Ufinal (W/m ℃) 149.3646624 Error % 25.31766881

205

Table 127: Properties of T-103 condenser.

T-103 CONDENSER PROPERTIES Material Carbon steel 2 K (W/m ℃) 45 d0 (m) 0.016 Wall thickness (m) 0.002 di (m) 0.012 L(m) 4 2 ATube surface (m ) 0.150796447 Number of tubes 212.6047708 Pt (m) 0.02 Db (m) 0.373488554 BDC (m) 0.055 Ds (m) 0.428488554 Baffle spacing (m) 0.107122139 de (m) 0.0157988 As (m) 0.091801221

During the designing stage of heat exchangers, an important factor should be taken in consideration which is the safety. Furthermore, this process deals with high thermal conditions.

Hence, some steps are needed to be followed in order to ensure the safety for the operators, the environment and the process itself including the heat exchangers.

During the design stage, make sure the below steps are satisfied: 1. Heat exchangers should be designed to withstand the possible increase in both pressure and temperature.

2. Insulators should be utilized to cover high temperature surfaces.

3. An alarm system should be installed.

4. The environment should be safe for the maintenance.

5. Grounding system.

During the operating stage, do the following: 1. High pressure heat exchangers should be avoided and SOP (standard operating procedure) should be followed.

2. Hot surfaces should be kept away to prevent injuries such as skin burn.

3. A regular maintenance should be performed for the tubes to avoid tube leaking.

4. If there is a possibility of a slurry flowing inside the tubes, a filter should be installed to remove it.

206

During the maintenance, do the following: 1. The LOTO (lock out tag out) technique should be performed when a heat exchanger is under maintenance.

2. For heat exchangers, any hazardous chemicals should be removed.

3. Caution should be exercised when a cleaning material is selected to clean the tubes.

4. The pressure in the heat exchangers should be removed (pressure gauge should be zero bar).

Fired heaters are utilizing the energy obtained from the reaction between both the air and the fuel. Moreover, this huge energy is shifted to the process fluid. Furthermore, new components will be produced due to the reaction between the air and the fuel known as combustion products. In the fired heaters, the process stream is introduced to the radiant zone in order to gain heat from the reaction between the air and the fuel. Also, the methane is used as the fuel. In addition, the reaction of air and fuel will produce oxygen, nitrogen, water, carbon dioxide and heat.

Figure 124: Fired Heater.

In order to design fired heater, the following steps need to be performed.

1. Assume 𝛼

𝛴𝑄

𝑐𝑝

𝐴𝑐𝑝

= 2* Average flux

2. Assume Ts (tube surface temperature), then use Figure 125 to find TG (temperature of the gas).

207

Figure 125: Flue gas temperature.

3. Calculate the fuel heat.

𝑄𝐹 =

𝐷𝑢𝑡𝑦 𝑜𝑓 ℎ𝑒𝑎𝑡𝑒𝑟 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦

4. Calculate mass flow rate of the required air.

𝑚̇𝑎𝑖𝑟 =

𝑚̇𝑎𝑖𝑟 𝑚̇ 𝑚̇𝐹𝑢𝑒𝑙 𝐹𝑢𝑒𝑙

5. Assume excess air of a 25%. 𝑎𝑖𝑟 = 1.25 𝑚̇𝑎𝑖𝑟

6. Calculate the heat of air inlet.

𝑄𝑎𝑖𝑟,𝑖𝑛 = 𝑚̇𝑎𝑖𝑟 𝑐𝑝,𝑎𝑖𝑟 (𝑇𝑎𝑖𝑟,𝑖𝑛 − 𝑇𝑟𝑒𝑓 ) Where 𝑇𝑟𝑒𝑓 =15.55 ℃

208

7. Calculate the absorbed heat by the furnace wall. 𝑄𝑤𝑎𝑙𝑙 = 0.02𝑄𝐹 8. Calculate the exhaust heat of the gases. 𝑄𝑒𝑥ℎ𝑎𝑢𝑠𝑡 = 𝑚̇𝐹𝑢𝑒𝑙 (1 + 𝐺)𝐶𝑃,𝑎𝑣𝑒𝑟𝑎𝑔𝑒 (𝑇𝐺 − 𝑇𝑟𝑒𝑓 ) 9. Calculate the net heat. 𝑄 = 𝑄𝑓𝑢𝑒𝑙 + 𝑄𝑎𝑖𝑟 − 𝑄𝑤𝑎𝑙𝑙 −𝑄𝑒𝑥ℎ𝑎𝑢𝑠𝑡 10. Calculate the number of tubes for heat exchange. 𝑁𝑡𝑢𝑏𝑒𝑠 =

𝑄 2𝜋𝑟𝐿𝑞

11. Calculate the area of the cold plane.

Acp = ctc * L * N 12. Find α from Figure 126 for total one row.

Figure 126: The relation between α and ctc/d0.

13. Assume the furnace shape as in Figure 127 ,then calculate AT(total exposed area).

209

Figure 127: Assumed furnace shape.

14. Calculate AR (effective refracting surface). 𝐴𝑅 = 𝐴𝑇 − 𝛼 𝐴𝑐𝑝 15. Find the gas emissivity from Figure 128 based on the product of pL.

Figure 128: Gas emissivity.

210

𝛴𝑄

16. Find f (overall heat exchanger factor) from Figure 129 based on the gas emissivity and 𝛼 𝐴 . 𝑐𝑝

Figure 129: The relation between ΣQ/(α Acp ) and friction factor. 𝛴𝑄

17. Calculate 𝛼 𝐴

𝑐𝑝

𝑓

then fined the new value for TG from Figure 125

This sample calculation is done for the unit H-101 and some of the needed data are obtained from Aspen HYSYS.

Assumptions and data from Aspen HYSY:

Efficiency = 82.5%, Tair,inlet =25 ℃ , required duty = 152300000 𝑚̇𝐹𝑢𝑒𝑙 = 4646.64

𝐾𝑔 ℎ

𝐾𝐽 ℎ

, di = 0.0889 m, d0 = 0.4 m L = 3.8 m

𝐾𝐽

Average flux = 196592.86 𝑚2 ℎ , Ts = 650 ℃, ctc = 0.183 m, P = 0.2413 atm

211

Steps for the calculations: 𝛴𝑄

𝐾𝐽

𝛼𝑐𝑝 𝐴𝑐𝑝

= 2* Average flux = 2 * 196592.86 = 393185.72 𝑚2 ℎ

From Figure 125 , TG = 1800 °F = 982.22 ℃

𝑄𝐹 =

𝑚̇𝑎𝑖𝑟 =

𝐷𝑢𝑡𝑦 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦

=

152300000 0.825

= 184606060.6

𝐾𝐽 ℎ

𝑚̇𝑎𝑖𝑟 𝐾𝑔 𝑚̇𝐹𝑢𝑒𝑙 = 20.55 ∗ 4646.64 = 95498.96 𝑚̇𝐹𝑢𝑒𝑙 ℎ

𝑚̇𝑎𝑖𝑟 = 1.25 ∗ 𝑚̇𝑎𝑖𝑟 = 1.25 ∗ 95498.96 = 119373.70

𝐾𝑔 ℎ

𝑄𝑎𝑖𝑟,𝑖𝑛 = 𝑚̇𝑎𝑖𝑟 𝑐𝑝,𝑎𝑖𝑟 (𝑇𝑎𝑖𝑟,𝑖𝑛 − 𝑇𝑟𝑒𝑓 ) = 95498.965 ∗ 1.012 ∗ ( 25 − 15.55 ) = 913000

𝑄𝑤𝑎𝑙𝑙 = 0.02𝑄𝐹 = 0.02 ∗ 184606060.6 = 3692121.212

𝐾𝐽 ℎ

𝐾𝐽 ℎ

𝑄𝑒𝑥ℎ𝑎𝑢𝑠𝑡 = 𝑚̇𝐹𝑢𝑒𝑙 (1 + 𝐺)𝐶𝑃,𝑎𝑣𝑒𝑟𝑎𝑔𝑒 (𝑇𝐺 − 𝑇𝑟𝑒𝑓 ) = 4646.64 ∗ (1 + 20.55 ) ∗ 1.279 ∗ ( 982.22 − 15.55 ) = 123817123.8

𝐾𝐽 ℎ

𝑄 = 𝑄𝑓𝑢𝑒𝑙 + 𝑄𝑎𝑖𝑟 − 𝑄𝑤𝑎𝑙𝑙 −𝑄𝑒𝑥ℎ𝑎𝑢𝑠𝑡 = 184606060.6 + 913294.8019 − 3692121.212 − 123817123.8 = 58010110.38

𝐾𝐽 ℎ

212

𝑁𝑡𝑢𝑏𝑒𝑠 =

𝑄 58010110.38 = = 61.79 2𝜋𝑟𝐿𝑞 2𝜋 ∗ 0.2 ∗ 3.8 ∗ 196592.86

Acp = ctc * L * N = 0.183 * 3.8 * 61.79 = 42.97 m2

From Figure 126 , α = 0.99 AT (Total exposed area) = 50 m2

𝐴𝑅 = 𝐴𝑇 − 𝛼 𝐴𝑐𝑝 = 50 − 0.99 ∗ 42.97 = 7.45 𝑚2 P*L = 0.2413 * 12.46 = 3 atm ft From Figure 128 , the gas emissivity = 0.55

From Figure 129 , f (overall heat exchanger factor) based on the gas emissivity and 𝛴𝑄 𝑖𝑠 = 0.64 𝛼 𝐴𝑐𝑝 𝛴𝑄 1 1 𝐵𝑇𝑈 ∗ = 34622 ∗ = 54096.87 𝛼 𝐴𝑐𝑝 𝑓 0.64 ℎ 𝑓𝑡 2 From Figure 125 , the new value for TG = 1950 °F Error % =

1950 − 1800 ∗ 100 = 8.33 % 1800

213

Table 128: Specification for H-101.

H-101 Material Duty (KJ/h) Efficiency% 𝑚̇fuel (Kg/h) 𝑚̇air /𝑚̇fuel Tinlet,air (℃) di (m) do(m) L(m) q (kJ/h.m2) Ts (℃) 𝛴𝑄 ( ) 𝛼𝑐𝑝 𝐴𝑐𝑝 intial TG,initial (℃) QF (KJ/h) 𝑚̇air (Kg/h) Air (Kg/h) Qair (KJ/h) Qwall (KJ/h) Qexhaust (KJ/h) Q (kJ/h) N (tubes) Acp (m2) α AT (m2) AR (m2) P (atm) pL (atm.m) Ɛ 𝐴𝑅 𝛼 𝐴𝑐𝑝 f 𝑄 (α Acp f) (Btu/ h.ft2)

Stainless steel 1.52E+08 82.5 4646.64 20.55 25 0.0889 0.4 3.8 196592.86 650

TG,final (℃) Error%

1950 8.33

393185.72 982.22 1.85E+08 95498.96 119373.70 9.13E+05 3.69E+06 1.24E+08 5.80E+07 61.79 42.971 0.99 50 7.458 0.2413 0.916 0.55 0.175 0.64 54096.87

214

Table 129: Specification for H-102.

H-102 Material Duty (KJ/h) Efficiency% 𝑚̇ fuel (Kg/h) 𝑚̇ air /𝑚̇ fuel Tinlet,air (℃) di (m) do(m) L(m) q (kJ/h.m2) Ts (℃) 𝛴𝑄 ( ) 𝛼𝑐𝑝 𝐴𝑐𝑝 intial TG,initial (℃) QF (KJ/h) 𝑚̇ air (Kg/h) Air (Kg/h) Qair (KJ/h) Qwall (KJ/h) Qexhaust (KJ/h) Q (kJ/h) N (tubes) Acp (m2) α AT (m2) AR (m2) P (atm) pL (atm.m) Ɛ 𝐴𝑅 𝛼 𝐴𝑐𝑝 f 𝑄 (α Acp f) (Btu/ h.ft2)

Stainless steel 4.48E+07 82.5 1367.30 20.55 25 0.0889 0.2 3.8 196592.86 650

TG,final (℃) Error%

2000 11.11

393185.72 982.22 5.43E+07 28101.11 35126.39 2.69E+05 1.09E+06 3.64E+07 1.71E+07 36.37 41.47 0.95 50 10.60 0.2414 0.917 0.55 0.269 0.57 60740.35

215

Table 130: Specification for H-103.

H-103 Material Duty (KJ/h) Efficiency% 𝑚̇ fuel (Kg/h) 𝑚̇ air /𝑚̇ fuel Tinlet,air (℃) di (m) do(m) L(m) q (kJ/h.m2) Ts (℃) 𝛴𝑄 ( ) 𝛼𝑐𝑝 𝐴𝑐𝑝 intial TG,initial (℃) QF (KJ/h) 𝑚̇ air (Kg/h) Air (Kg/h) Qair (KJ/h) Qwall (KJ/h) Qexhaust (KJ/h) Q (kJ/h) N (tubes) Acp (m2) α AT (m2) AR (m2) P (atm) pL (atm.m) Ɛ 𝐴𝑅 𝛼 𝐴𝑐𝑝 f 𝑄 (α Acp f) (Btu/ h.ft2)

Stainless steel 3.79E+07 82.5 1157.16 20.55 25 0.0889 0.15 3.8 196592.86 650

TG,final (℃) Error%

2050 13.88

393185.72 982.22 4.60E+07 23782.31 29727.89 2.27E+05 9.20E+05 3.08E+07 1.44E+07 41.04 46.79 0.89 50 8.35 0.241 0.917 0.55 0.2 0.55 62949.09

216

Table 131: Specification for H-104.

H-104 Material Duty (KJ/h) Efficiency% 𝑚̇ fuel (Kg/h) 𝑚̇ air /𝑚̇ fuel Tinlet,air (℃) di (m) do(m) L(m) q (kJ/h.m2) Ts (℃) 𝛴𝑄 ( ) 𝛼𝑐𝑝 𝐴𝑐𝑝 intial TG,initial (℃) QF (KJ/h) 𝑚̇ air (Kg/h) Air (Kg/h) Qair (KJ/h) Qwall (KJ/h) Qexhaust (KJ/h) Q (kJ/h) N (tubes) Acp (m2) α AT (m2) AR (m2) P (atm) pL (atm.m) Ɛ 𝐴𝑅 𝛼 𝐴𝑐𝑝 f 𝑄 (α Acp f) (Btu/ h.ft2)

Stainless steel 3.26E+07 82.5 993.21 20.55 25 0.0889 0.2 3.8 196592.86 650

TG,final (℃) Error%

1900 5.55

393185.72 982.22 3.95E+07 20412.72 25515.90 1.95E+05 7.89E+05 2.65E+07 1.24E+07 26.43 20.08 1 50 29.91 0.241 0.916 0.55 1.48 0.75 46162.66

217

References 1. Serth, R. W. (2007). Process heat transfer: Principles and applications. Elsevier Academic Press.

2. Turton, R., Bailie, R. C., Whiting, W. B., & Shaeiwitz, J. A. (2009). Analysis, synthesis and design of Chemical Processes. Prentice Hall.

3. Shawabkeh, R. A. (n.d.). Furnace Heater Design - Researchgate. Retrieved April 29, 2022, from https://www.researchgate.net/profile/ReyadShawabkeh/publication/281460206_Handout_Steps_for_design_of_Furnace_Fired_Hea ter/links/55e97cc908aeb651626480d1/Handout-Steps-for-design-of-Furnace-FiredHeater.pdf

4. Shawabkeh, R. A. (n.d.). Handout step-by-step by step for heat exchanger design. Retrieved April 29, 2022, from https://www.researchgate.net/profile/ReyadShawabkeh/publication/281460350_Handout_Step-bystep_for_Heat_Exchanger_design/links/55e97c3008ae65b6389af60c/Handout-Step-bystep-for-Heat-Exchanger-design.pdf

218

4.5

Piping Design

By: Mana Aljamhoor

219

Introduction It is one of the most important steps while designing a plant to design pipes and compressors.

The piping design include the suitable size, construction material which is crucial in minimizing the maintenance cost in the industry. Due to any outflow in the process or anything that could affect the economy of the plant or the product quality, this design was performed.

A full classification of each stream in the process will be provided in this section. Based on the classified conditions of the streams, all the design parameters will be calculated along with best material of construction. Moreover, calculation for the used compressors will be elaborated in this section.

Pipes objective in the plant is to work as a transportation medium for the reactants and the products. In addition, they occupy a massive area of the plant and therefore their design should follow the highest standards and guarantee the best quality with the least possible cost.

During the design of piping, there are several aspects and consideration should be taken in account. These aspects include pressure drop inside the pipes, material used in pipes construction, pipes sizing and finally the interior classification of the pipe walls. Utilizing the previous chapter (Simulation), the data in this section was obtained.

Titration was applied to evaluate the diameter of the pipes in order to meet the regulation.

The pressure drop is evaluated at psi/100 ft, since the length of the pipes is not provided.

Furthermore, calculation and design of all pipes and compressors in this section follow the heuristics obtained from “Analysis, Synthesis and Design of Chemical Process” textbook. Finally, the members of the group envisage the layout of the plant, and it will be elaborated in the section of layout.

The regulations that are illustrated by a special and official organization are known as standards. These standards help in the construction of industrial plants at high level of safety. The following standards were collected from various organizations in piping design section:

Table 132: The utilized standards

Design

Standard

Pipes

ASME

MOC

ASTM

Safety

WHO

220

Pipe Design

Usage of a suitable material is one of the most important factors the design of piping concentrate on, where the improper material use lead to some serious problems such as corrosion.

On the other hand, the usage of an over specified material will cost a lot and will be considered as a lose money. Carbon steel (CS) is a reliable material, it is hard, tough, and considered as a cheap material related to other material of construction. However, carbon steel is suitable for a specific range of temperature, and according to Figure 1 and ASTM standards, the maximum temperature for such material is around 400C. Due to that fact, the streams with temperature only below 400 C will utilize the carbon steel material. The applies carbon steel is ASME SA515-Grade 55, and the CA is assumed to be 3.15 mm. For the streams with temperature higher than 400 C, stainless steel material will be installed, which is stronger than carbon steel according to Figure 2 and more expensive on economical scale. The installed material is ASME- SA-240 Grade 316, which according to Table 2 can stand for the process temperature.

Figure 130: The temperature against the maximum allowable stress for Carbon Steel.

221

Figure 131: The temperature against the maximum allowable stress for stainless steel.

Table 133: Maximum surface temperature for stainless steel.

222

The following steps will be applied for each stream, and the pipe carrying stream one will be illustrated as a sample calculation: 1.

2.

3.

4.

5.

6.

7.

Calculate the mass flow rate in the pipes.

Using the data from Aspen HYSYS, calculate the mass density.

Divide the mass flow rate over density in order to get the volumetric flow rate.

Assume a valid inner dimeter.

Use the circle formula to compute the cross-sectional area.

Calculate the fluid velocity and compare it with heuristics in Table 4.

Find the roughness of the pipe.

For stainless steel it is 0.015 mm, and for carbon steel it falls between 0.02mm and 0.05mm and it assumed to be 0.03mm in this project.

8. Utilizing the following formula determine the type of flow by calculating the Reynolds number: 𝑑𝑢𝜌 𝑅𝑒 = 𝜇 - The flow is laminar, if Re is less than 2100.

- The flow is turbulent or transition, if Re is more than 2100.

9. Determine the factor for friction based on flow type: -

If the flow is laminar then: 𝑓 =

-

If it is turbulent then:

𝑅𝑒 64 1

𝑓 =

2

7 0.9 3.24𝜀 (2 ∗ log ((𝑅𝑒) + ( ))) 𝑑 10. Find the drop pressure inside the pipes.

11. Use the following formula to find the minimum wall thickness: 𝑡 =

𝑃𝑑0 + 𝐶𝐴 2𝑆𝐸 − 1.2𝑃

Where, P represents the pressure, 𝑑0 represents the dimeter, S represents the maximum allowable stress, E represents the weld efficiency which is taken between (0.6 ~ 1), and CA represents the corrosion allowance.

Taken E to be 1 as an assumption, and CA to be 3.15 mm.

223

S could be found using the figures, Figure 1 for carbon steel and Figure 2 for stainless steel.

Table 134: ASME standards for steel pipes dimensions.

224

Table 135: Acknowledged velocity range inside pipes.

The following tables will provide a whole informative description for each stream in the process in order to guarantee the best design.

Table 136: Stream information.

Stream Temperature # (C) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

51.38 44.24 46.74 72.2 22.29 -13.63 66.24 146.2 226.2 306.2 650 556.7 650 572 650 583.8 650 593.1 534 479.5 430.2 287.2 223.8 150 252.5

Pressure (bar)

Mass Flowrate (Kg/hr)

Mass Density (Kg/m3)

Volumetric Flowrate (m3/h)

11 11 11 10 9 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 3.04 15

1.68E+05 2.409e+005 240900.00 1.02E+05 138600.00 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05

496.6 183.2 58.53 497.4 496.2 27.01 4.932 3.924 3.268 2.804 1.749 1.739 1.562 1.566 1.433 4.27E-02 1.339 1.35 1.45 1.555 1.665 2.094 2.366 2.789 11.19

338.0990737 0.013149563 4115.838032 205.6694813 279.3228537 5131.432803 28102.18978 35321.10092 42411.26071 49429.38659 79245.28302 79700.97757 88732.39437 88505.74713 96720.16748 3248945.148 103510.0822 102666.6667 95586.2069 89131.8328 83243.24324 66189.11175 58579.88166 49695.23127 12386.05898

Volumetric Flowrate (m3/s)

Viscosity (cP)

0.093916409 0.1055 3.65266E-06 0.1035 1.143288342 0.00926 0.057130411 0.1081 0.077589682 0.1021 1.425398001 0.1462 7.806163828 0.009427 9.811416922 0.01172 11.78090575 0.01404 13.73038516 0.01631 22.01257862 0.02432 22.13916044 0.02344 24.64788732 0.0253 24.58492976 0.02435 26.86671319 0.02591 902.4847632 0.02497 28.7528006 0.02632 28.51851852 0.02543 26.55172414 0.02419 24.75884244 0.02302 23.12312312 0.02194 18.38586437 0.0185 16.27218935 0.01663 13.80423091 0.01435 3.440571939 0.01773

225

26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

150 23.89 85.84 119.4 5 5 5 -0.1373 -240.5 12.22 -40.55 -40.55 69.86 53.38 45.18 57.24 57.24 57.24 57.24 30.97

15 15 40 65 65 65 65 12 12 12 25 25 28 20 18.5 20 20 20 20 11

1.39E+05 1.39E+05 1.39E+05 1.39E+05 1.39E+05 9335 1.29E+05 1.29E+05 354.9 1.29E+05 1341 7.98E-04 1.28E+05 1.28E+05 4.57E+04 8.18E+04 8184 7.37E+04 7.29E+04 7.29E+04

14.24 22.49 53.43 81.57 209.7 22.88 511.2 155.2 24.61 515.3 41.17 429.5 407.2 152.4 469.3 435.2 435.2 435.2 435.2 82.5

9733.146067 6162.738995 2594.048287 1699.154101 660.944206 407.9982517 252.7386541 832.4742268 14.42096709 250.1455463 32.57226136 1.85891E-06 313.1139489 836.6141732 97.37907522 188.0514706 18.80514706 169.2555147 167.578125 884

2.703651685 1.711871943 0.720568969 0.47198725 0.183595613 0.113332848 0.070205182 0.231242841 0.004005824 0.069484874 0.00904785 5.16363E-10 0.086976097 0.232392826 0.027049743 0.05223652 0.005223652 0.047015421 0.046549479 0.245555556

0.01469 0.01073 0.014 0.01643 0.072539 0.009848 0.09599 0.1124 0.002365 0.09967 0.009507 0.06299 0.05547 0.06697 0.05095 0.07273 0.07273 0.07273 0.07274 0.0947

Stream 1: ṁ = 1.68E + 05

𝐾𝑔 ℎ

𝜌 = 496.6 𝐾𝑔/𝑚3 ṁ 𝑉̇ = 𝜌 =

Assuming that the outer inner diameter = 202.74mm

1.68E+05 𝐾𝑔/ℎ 496.6 𝐾𝑔/𝑚3

diameter

𝐴 = 𝑢=

= 338.099

=

219.1

𝑚3 ℎ

1ℎ

∗ 3600𝑠 = 0.093

mm,

SCH

𝑚3 𝑠

40,

t

=

8.18mm,

and

𝜋(0.20274)2 = 0.032 𝑚2 4

𝑉̇ 0.093 𝑚 𝑓𝑡 = = 2.909 = 9.544 𝐴 0.032 𝑠 𝑠

The fluid is vapor, and its velocity falls in the accepted range according to Table 4, so the assumption is valid.

226

P= 11 bar The minimum wall thickness:

𝑡 =

𝑡=

𝑃𝑑0 + 𝐶𝐴 2𝑆𝐸 − 1.2𝑃

11 ∗ 219.1 = 4.169 𝑚𝑚 2 ∗ 1100 ∗ 1 − 1.2 ∗ 11

The real wall thickness is higher than the minimum one, so the assumption is valid.

Since the pipe is stainless steel, ε is 0.015 mm. 𝑅𝑒 =

𝑅𝑒 =

𝑑𝑢𝜌 𝜇

0.20274 ∗ 2.909 ∗ 496.9 = 27763 10.55 ∗ 10−2

Since Re is more than 2100, it is a turbulent flow.

The friction factor:

1

𝑓=

0.9

7 (2 ∗ log 〖((27763)

= 0.024

3.24 ∗ 0.015 + ( 0.20274 )))2 〗

The drop pressure: 𝛥𝑃 = 𝑓

𝛥𝑃 = 0.024 ∗

𝐿 ∗ 2 ∗ 𝜌 ∗ 𝑢2 𝐷

10 ∗ 2 ∗ 496.9 ∗ 2.9092 0.20274 𝛥𝑃 = 2.892 𝑝𝑠𝑖

227

The following tables represent each stream in the process and a whole justification for the stream parameters including the dimeter, wall thickness, and pressure drop in the pipes.

Table 137: The parameters for Design 1.

Stream #

SCH

Thickness (m)

OD (m)

Inner D (m)

cross section area(m^2)

velocity(ft/s)

Re

Stream Phase

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40

0.00818 0.0127 0.01113 0.00818 0.00516 0.01427 0.01427 0.01427 0.01427 0.01427 0.01427 0.01427 0.01427 0.01427 0.01427 0.01784 0.01427 0.01427 0.01784 0.01784 0.01784 0.01784 0.01784 0.01784 0.01784 0.01113 0.00818

0.2191 0.4064 0.3556 0.2191 0.2191 0.4572 0.4572 0.4572 0.4572 0.4572 0.4572 0.4572 0.4572 0.4572 0.4572 0.61 0.4572 0.4572 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.3556 0.2191

0.20274 0.381 0.33334 0.20274 0.20878 0.42866 0.42866 0.42866 0.42866 0.42866 0.42866 0.42866 0.42866 0.42866 0.42866 0.57432 0.42866 0.42866 0.57432 0.57432 0.57432 0.57432 0.57432 0.57432 0.57432 0.33334 0.20274

0.032283 0.114009 0.08727 0.032283 0.034235 0.144316 0.144316 0.144316 0.144316 0.144316 0.144316 0.144316 0.144316 0.144316 0.144316 0.259058 0.144316 0.144316 0.259058 0.259058 0.259058 0.259058 0.259058 0.259058 0.259058 0.08727 0.032283

9.544484 0.000105 42.98043 5.806018 7.435601 3.240411 17.74605 22.30466 26.78198 31.2138 50.04203 50.32979 56.03297 55.88985 61.07711 1142.936 65.36483 64.83222 336.2596 313.554 292.8387 232.8445 206.0763 174.8212 43.57252 101.6403 173.9732

27763 0.216062 276015.2 16508.9 22996.21 782.1869 12130.66 9757.314 8144.994 7011.387 4702.127 4878.657 4519.989 4696.333 4413.575 3418.207 4344.822 4496.882 35284.26 37077.6 38902.75 46136.56 51324.49 59479.18 48140.23 100106.3 225336.6

L L V/L L L L V V V V V V V V V V V V V V V V V V V V V

228

28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40

0.01784 0.01784 0.00818 0.00818 0.0127 0.01031 0.00655 0.01031 0.00655 0.00655 0.01031 0.01113 0.00655 0.01113 0.00655 0.00655 0.00655 0.01113

0.61 0.61 0.2191 0.2191 0.4064 0.3239 0.1413 0.3239 0.1413 0.1413 0.3239 0.3556 0.1413 0.3556 0.1413 0.3556 0.1413 0.3556

0.57432 0.57432 0.20274 0.20274 0.381 0.30328 0.1282 0.30328 0.1282 0.1282 0.30328 0.33334 0.1282 0.33334 0.1282 0.3425 0.1282 0.33334

0.259058 0.259058 0.032283 0.032283 0.114009 0.07224 0.012908 0.07224 0.012908 0.012908 0.07224 0.08727 0.012908 0.08727 0.012908 0.092132 0.012908 0.08727

9.125518 5.977399 18.65835 11.51773 2.020268 10.50197 1.018136 3.155677 2.299637 1.31E-07 3.950047 8.736505 6.875068 1.963764 1.327664 1.674207 11.8312 9.231341

60966.16 51949.26 33331.71 16536.15 12494.51 13404.79 4139.944 15081.77 3891.391 0.00035 26805 20199.94 24745.24 11939.12 3104.357 10458.4 27660.02 8171.023

V V L V L L V L V L L L L L L L L L

Table 138: The parameters for Design2.

Stream

εAbsolute

1/sqar(f)

f

Pdrop (Kpa)

Pdrop (psi)

velocity(m/s) MOC

εAbsolute

1

0.00003

0.024051392

19.9440294

2

0.00003

0.136396539

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

0.00003 0.00003 0.00003 0.00003 0.00003 0.00003 0.00003 0.00003 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00003 0.00003 0.00003 0.00015

6.448072232 2.707686157 8.077212076 6.057787892 6.308628413 3.697524003 5.833244121 5.664570445 5.524416175 5.407989644 5.082228761 5.110372735 5.052034785 5.08128694 5.033812938 4.841414402 5.021799885 5.048115667 6.582856128 6.61717357 6.650246668 6.864044103 6.94498697 7.05656405 6.794456629

2.892636905

2.909194209

CS

0.00003

2.69279E-09

3.90556E-10

3.20383E-05

CS

0.00003

0.015327701 0.027250337 0.02512639 0.07314388 0.029388654 0.031164921 0.032766286 0.034192299 0.038716098 0.038290836 0.039180262 0.038730451 0.039464432 0.042663402 0.03965347 0.039241121 0.023076571 0.022837836 0.022611246 0.021224617 0.02073276 0.020082299 0.0216616

18.47609454 8.37520367 12.26960457 0.179841659 0.395725027 0.527441049 0.66585868 0.809817537 1.470072186 1.46228543 1.665801296 1.642470928 1.828927768 15.38390607 1.966697237 1.930387632 24.48134402 22.59209678 20.89018277 15.59176132 13.47951838 11.07635575 2.977778829

2.679730953 1.214720593 1.779555689 0.026083827 0.057395063 0.076498857 0.096574637 0.117454104 0.213215944 0.212086571 0.241604051 0.238220268 0.265263546 2.231246933 0.285245318 0.279979055 3.550718753 3.276706607 3.029864849 2.261393789 1.955038851 1.60648958 0.431890305

13.10059533 1.769695662 2.266398644 0.98768929 5.409060773 6.798544275 8.163245941 9.514082644 15.2529947 15.340706 17.07905745 17.03543278 18.61653017 348.3710972 19.92344118 19.76110203 102.4931794 95.57241806 89.25832437 70.97187683 62.81281068 53.28616353 13.28106435

CS CS CS CS CS CS CS CS SS SS SS SS SS SS SS SS SS SS SS CS CS CS CS

0.00003 0.00003 0.00003 0.00003 0.00003 0.00003 0.00003 0.00003 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00003 0.00003 0.00003 0.00015

229

26 27 28 29 30 31 32 33 34 35 36

0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015

37

0.00015

38 39 40 41 42 43 44 45

0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015

7.097263048 7.132821115 6.949105208 6.844955592 6.38028444 5.948731511 5.810956144 5.84652069 4.941810648 5.930038887 4.896820409 7.731325046 6.321820163 6.142719541 6.098594721 5.769858239 4.731080578 5.674882707 6.156853168 5.49147947

0.019852637 0.019655194 0.020708194 0.02134316 0.024565178 0.02825864 0.029614527 0.029255331 0.040947538 0.028437075 0.041703418

32.55912605 245.2405924 0.596195973 0.402494781 32.87198768 1.572178688 0.602683547 6.136132071 0.030280517 1.78808014 0.263198516

4.722301983 35.56914072 0.086470915 0.058376933 4.767678726 0.22802524 0.087411858 0.889970714 0.004391818 0.259339098 0.038173717

30.98032694 53.02766554 2.78149186 1.821933432 5.687134945 3.510645973 0.615785325 3.20103831 0.310331566 0.961862182 0.700937796

0.016729853

3.58761E-15

5.20339E-16

4.00027E-08

0.025021637 0.026501999 0.026886883 0.03003791 0.044676517 0.03105176 0.026380463 0.033160515

1.947980906 3.436782909 17.28850341 0.56201789 0.993474596 0.410991756 46.58445819 2.599069074

0.282530744 0.498463218 2.507485423 0.081513803 0.144091308 0.059609315 6.756504427 0.376963099

1.203988921 2.662919105 2.095546071 0.598562479 0.404676795 0.510304378 3.606192405 2.813746843

CS CS CS CS CS CS CS CS CS CS CS CS

0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015

CS CS CS CS CS CS CS CS

0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015 0.00015

0.00015

Table 139: The Parameters of Design 3.

Stream #

S

E

CA

Wall Thickness (mm)

Minimum wall thickness (mm)

Flow Type

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

1100 1100 950 950 950 950 950 950 950 950 750 750 750 750 750 750 750 750 750 750 750 950

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15

8.18 12.7 11.13 8.18 5.16 14.27 14.27 14.27 14.27 14.27 14.27 14.27 14.27 14.27 14.27 17.84 14.27 14.27 17.84 17.84 17.84 17.84

4.169818913 5.066498994 5.093364427 4.223834746 4.144611476 3.837175377 3.837175377 3.837175377 3.837175377 3.837175377 4.020868886 4.020868886 4.020868886 4.020868886 4.020868886 4.31679284 4.020868886 4.020868886 4.31679284 4.31679284 4.31679284 4.070679705

Turbulent Laminar Turbulent Turbulent Turbulent Laminar Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent

230

23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

950 950 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15

17.84 17.84 17.84 11.13 8.18 17.84 17.84 8.18 8.18 12.7 10.31 6.55 10.31 6.55 6.55 10.31 11.13 6.55 11.13 6.55 6.55 6.55 11.13

4.070679705 4.070679705 7.09812099 5.44152154 4.543721357 13.82509294 20.74227144 9.360226202 9.360226202 14.82059378 4.815153734 3.853879941 4.815153734 4.626958525 4.626958525 7.069793205 6.213786765 4.239034806 6.213786765 4.328308824 6.297977941 4.328308824 4.826760563

Laminar Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Laminar Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent Turbulent

Compressor Design Compressors are widely used in industries, and the main aim of compressors is to increase the pressure of a gas fluid. Both compressors C-101 and C-102 are used in this process for the purpose of increasing pressure. However, it is normal that the temperature raises with increasing pressure and therefore the material of construction for the equipment must be taken in consideration. The material chosen for both compressors is carbon steel ASME SA515-Grade 55, since the material is inexpensive and the fluid is less than 400 C. For the compressor’s calculation, “Analysis, Synthesis and Design of Chemical Process” textbook was used to utilize the heuristics.

The first law of thermodynamics is applied: 𝛥Ḣ + 𝛥𝐸𝐾 + 𝛥𝐸𝑃 = 𝑊𝑠 + 𝑄 Assume the kinetic and potential energies are neglected, also the process is adiabatic, then: 𝛥Ḣ = 𝑊𝑠

231

It has been proved that the enthalpy equals the shaft work for the compressors.

This formula is utilized to calculate the supplied power to compressors: 𝛶−1 𝛶

𝛶−1 𝑃 𝑍 ∗ ṅ ∗ 𝑅𝑇𝑖 ( 𝛶 ) (( 𝑃0 ) 𝑖 𝑊=

− 1)

𝜀

For C-101: 8.314𝐾𝐽 1.130 − 1 1500 𝐾𝑃𝑎 (1.130−1 ) 1.130 ∗ 423.15𝐾 ( − 1) 𝐾𝑚𝑜𝑙 1ℎ 1.130 ) ( 304 𝐾𝑃𝑎 ) 𝐾𝑚𝑜𝑙. 𝐾 𝑊 = 0.9914 ∗ 4329.845 ∗ ∗ ℎ 3600𝑠 0.75

𝑊 = 9800.148 𝐾𝑤

For the outlet temperature, the following formula is applied: 1 𝑃0 𝛶−1 𝑇0 = 𝑇𝑖 (1 + (( ) 𝛶 − 1) 𝜀 𝑃𝑖

1.130−1 1.130

1 1500 𝑇0 = 423.15 (1 + (( ) 0.75 304

− 1))

𝑇0 = 677.93 𝐾

For C-102:

𝑊 = 0.9914 ∗ 4329.8459

𝐾𝑚𝑜𝑙 ℎ

1ℎ

∗ 3600𝑠 ∗

1.275−1 8.314𝐾𝐽 1.275−1 4000 𝐾𝑃𝑎 ( ) ∗297.0374𝐾( )( ) 1.275 −1) 𝐾𝑚𝑜𝑙.𝐾 1.275 1500 𝐾𝑃𝑎

0.75

232

𝑊 = 4288.639 𝐾𝑤

1 4000 𝑇0 = 297.0374 (1 + (( ) 0.75 1500

1.275−1 1.275

− 1))

𝑇0 = 489.356 𝐾 For C-103:

𝑊 = 0.8028 ∗ 4329.8459

𝐾𝑚𝑜𝑙 ℎ

1ℎ

∗ 3600𝑠 ∗

1.333−1 8.314𝐾𝐽 1.333−1 6500 𝐾𝑃𝑎 ( ) ∗358.9881𝐾( )( ) 1.333 −1) 𝐾𝑚𝑜𝑙.𝐾 1.333 4000 𝐾𝑃𝑎

0.75

𝑊 = 1983.377𝐾𝑤

1 6500 𝑇0 = 358.9881 (1 + (( ) 0.75 4000

1.333−1 1.333

− 1))

𝑇0 = 540.372 𝐾

Consideration of Safety There are special safety rules for each equipment at any industrial plant from an authorized organization, and simply these rules must be followed in order to inhibit any accident in the industry.

These restrictions are to be taken in account during the equipment design, and the following is safety rules for pipes and compressors:

Safety Rules for Pipes -

Ensure that suitable material of construction is carefully chosen.

The minimum wall thickness must be computed to inhibit fouling.

The temperature is to be taken as an essential factor.

Determine the chemicals corrosion level.

233

Safety Rules for Compressors -

The material of construction is to be chosen to suit the process conditions.

A continuous maintenance and checkout for the compressors.

Locate the compressors in a prober location that has high safety consideration.

Plant Layout Chemical engineering projects always start with (BFD), which gives a general idea of the process, then (PFD) which elaborate more about the process, and finally (P&ID) which gives the detailed ----------------------------------------------------------------------------------------------------------------structure of the process and the plant. Here in plant layout which require special people to agree on a suitable layout of the plant. The group members were summoned and read about the plant layout, and the whole members came out with a layout that is considered as the best taking in account what ----------------------------------------------------------------------------------------------------------------we have.

Mosque

Restaurant

Mosque

Warehouse

Warehouse

-------------------------------------------------------------------------

Laboratory

Restaurant

------------------

Laboratory

------------------

Utility

------------------ ---------------------------- ----------------------

-------------------------------------------------------------------------

Utility

---------------------------- ----------------------

---------------------------- ----------------------

----------------------------------------------------------------------------------------------------------------Workshop and Fire Maintenance Administration Production Plant Department Fire Water ----------------------------------------------------------------------------------------------------------------Department Tank Control Room Administration Production Plant Fire Workshop and Department Assembly Point Fire Water Maintenance ----------------------------------------------------------------------------------------------------------------Control Room Tank Department Emergency Hospital 00 Parking ParkingPoint Assembly ----------------------------------------------------------------------------------------------------------------Visitor Security Tank Farm Emergency Hospital 00 Parking Parking Department Department

-----------------------------------------------

----------------------------------------------Main Gate Visitor Security Figure 132: Plant Layout.

Department Department --------------------------------------------------------------------------------------------Main Gate Tank Farm

234

Summary In conclusion, the information for all streams were elaborated in order to design the pipes.

Also, all the pipes and compressors sample calculations were elaborated. Moreover, the suitable material of construction for pipes and compressors were selected, considering that carbon steel for operating at temperature lower than 400 C and stainless steel for those who operate above 400 C. Finally, the layout of the plant was designed by all team members and envisioned.

References •

•

L. UNITED STEEL INDUSTRY CO., “Steel Pipe Dimensions & Sizes Chart (Schedule 40, 80 Pipe) Means”, United-steel.com, 2020.

[Online].

Available: http://www.unitedsteel.com/newsshow/834.html. [Ac- cessed: 17- Mar- 2020].

POWER, 2017. 12 Tips for Centrifugal Pump Safety. POWER Magazine. URL https://www.powermag.com/12-tips-for-centrifugal-pump-safety/ (accessed 4.1.21).

•

R. Turton, R. Bailie, W. Whiting, J. Shaeiwitz and D. Bhattacharyya, Analysis, Synthesis, and Design of Chemical Processes, Fourth Edition.

•

Safety in design during piping engineering [WWW Document], n.d. https://www.hydrocarbonprocessing.com/magazine/2018/february2018/environment-andsafety/safety-in-design-during-piping-engineering (accessed 4.1.21).

•

Stainless Steel - High Temperature Resistance [WWW Document], 2002. . AZoM.com. URL https://www.azom.com/article.aspx?ArticleID=1175 (accessed 4.1.21).

URL

235

5

Economics & Heat Integration

236

Introduction The construction of any chemical plant requires a deep study about its economy whether it is suitable or not, in order to proceed the process. This chapter will focus on the economy of the propane dehydrogenation process. Results performed in the previous chapters will be utilized in this chapter in order to construct an overall study of the economy of the process. Moreover, some suggestions will be proposed regarding the utility cost to be minimized and environmental damage abatement, through preformation of heat integration.

The overall study will focus on many aspects including capital cost which gives an idea about the module cost, total bare module and grassroot costs, water operation, waste treatment, operating labor, utility, raw material, and fixed capital cost. The previous values will be calculated in order to calculate the cost for the manufacture.

As part of the process, cash will be consumed and produced unstable rate and at different time intervals throughout the lifetime of the process, beginning from the plant construction and continuously remaining through operation time. The cash flow diagrams will be utilized to give a clear demonstration about the process cash flow during plant lifetime.

Heat integration will be performed in order to maximize the process heat efficiency and minimize the costs through pinch analysis. The thermodynamics fundamentals will be applied to ensure the most profitable utilization of the heat of the process. Among any other methods, pinch analysis has been considered to be the best approach to accomplish heat integration.

237

1. For calculations, CAPCOST was used.

2. The parameters form both HYSYS and the equipment design report were utilized in the calculation of the cost.

3. 1,000,000 $ is assumed to be the cost of the land.

4. Taxation rate was assumed to be 2.5% Zakah.

5. The stream factor was assumed to be 0.95.

6. The operating hours 8322 per year.

7. 3 years are assumed to be the construction period.

8. The life cycle of the plant was assumed to be 12 years.

9. The feedstock for the process is LPG (propane) and the product is Propylene.

10. Cost of raw material and product: Table 140: Cost of raw materials and product.

Material Name LPG Propylene

Classification Raw Material Product

Price ($/kg) $ 0.74 $ (1.05)

Flowrate (kg/h) 38115.00 45660.00

Annual Cost $ 234,722,842 $ (398,221,681)

238

Bare Module Cost

239

Total Module and Grassroot Cost: Table 141: Total Module and Grass root costs.

Name C-101 C-102 C-103 D-101 D-102 D-103 E-101 E-102 E-103 E-104 E-105 E-106 E-107 E-108 E-109 E-110 E-111 E-112 E-113 E-114 E-115 H-101 H-102 H-103 H-104 R-101 R-102 R-103 R-104 T-101 T-102 T-103 V-101 Totals

Total Module Cost $ 6,050,000.00 $ 6,050,000.00 $ 5,250,000.00 $ 1,010,000.00 $ 1,010,000.00 $ 966,000.00 $ 129,250.12 $ 239,000.00 $ 247,000.00 $ 257,000.00 $ 269,000.00 $ 137,000.00 $ 129,000.00 $ 131,000.00 $ 249,000.00 $ 310,000.00 $ 267,000.00 $ 215,000.00 $ 130,000.00 $ 254,000.00 $ 130,000.00 $ 11,600,000.00 $ 5,700,000.00 $ 5,120,000.00 $ 4,780,000.00 $ 194,000.00 $ 194,000.00 $ 194,000.00 $ 194,000.00 $ 7,200,000.00 $ 2,440,000.00 $ 17,600,000.00 $ 492,000.00 $ 79,100,000

Grass Roots Cost $ 8,620,000.00 $ 8,620,000.00 $ 7,470,000.00 $ 1,440,000.00 $ 1,440,000.00 $ 1,380,000.00 $ 184,000.00 $ 292,000.00 $ 303,000.00 $ 315,000.00 $ 330,000.00 $ 195,000.00 $ 183,000.00 $ 186,000.00 $ 305,000.00 $ 442,000.00 $ 381,000.00 $ 306,000.00 $ 185,000.00 $ 311,000.00 $ 184,000.00 $ 15,300,000.00 $ 7,600,000.00 $ 6,800,000.00 $ 6,300,000.00 $ 215,000.00 $ 215,000.00 $ 215,000.00 $ 215,000.00 $ 8,900,000.00 $ 2,730,000.00 $ 20,300,000.00 $ 541,000.00 $ 102,400,000

240

Cost of Utility Summary

Table 142: Cost of utilities.

Common Utilities

Cost ($/GJ)

Electricity (110V - 440V)

16.8

Cooling Water (30°C to 45°C)

0.354

Refrigerated Water (15°C to 25°C)

4.43

Steam from Boilers Low Pressure (5 barg, 160°C)

13.28

Medium Pressure (10 barg, 184°C)

14.19

High Pressure (41 barg, 254°C)

17.7 Fuels

Fuel Oil (no. 2)

14.2

Natural Gas

11.1

Coal (FOB mine mouth)

1.72 Thermal Systems

Moderately High (up to 330°C)

12.33

High (up to 400°C)

13

Very High (up to 600°C)

13.88 Refrigeration

Moderately Low (5°C)

4.43

Low (-20°C)

7.89

Very low (-50°C)

13.11

241

Table 143: Annual utility cost for each equipment.

Name

Utility Used

C-101 C-102 C-103 D-101 D-102 D-103 E-101 E-102 E-103 E-104 E-105 E-106 E-107 E-108 E-109 E-110 E-111 E-112 E-113 E-114 E-115 H-101 H-102 H-103 H-104 R-101 R-102 R-103 R-104 T-101 T-102 T-103 V-101

NA NA NA Electricity Electricity Electricity

Efficiency

Actual Usage

Annual Utility Cost

0.9 0.9

Custom Custom Custom Custom

0.9

Custom

0.9

Cooling Water

0.9

Cooling Water

0.9

Cooling Water Refrigeration (5°C) Low-Pressure Steam Low-Pressure Steam Low-Pressure Steam Cooling Water Refrigeration (-50°C) Cooling Water Natural Gas Natural Gas Natural Gas Natural Gas

NA NA NA NA NA NA NA NA Total

2720 kilowatts 2720 kilowatts 2200 kilowatts 234 MJ/h 608 MJ/h 2290 MJ/h 2640 MJ/h 2970 MJ/h 25500 MJ/h 367 MJ/h 3860 MJ/h 6890 MJ/h 110000 MJ/h 7980 MJ/h 5410 MJ/h 140000 MJ/h 5660 MJ/h 5490 MJ/h 169000 MJ/h 53300 MJ/h 42100 MJ/h 36200 MJ/h 0 MJ/h 0 MJ/h 0 MJ/h 0 MJ/h

$ 1,370,000.00 $ 1,370,000.00 $ 1,107,000.00

$ 75,000.00 $ 1,080.00 $ 11,400.00 $ 254,000.00 $ 12,157,000.00 $ 881,900.00 $ 597,900.00 $ 410,000.00 $ 617,500.00 $ 16,200.00 $ 15,600,000.00 $ 4,927,000.00 $ 3,890,000.00 $ 3,346,000.00

$

27,900,000

242

Cash flow: Summary Table 144: Summary of cashflow.

Year

Investment

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

1.00 40.96 30.72 64.42

FCILSdk

dk

20.48 32.77 19.66 11.78 11.78 5.94

102.40 102.40 102.40 102.40 81.92 49.15 29.49 17.72 5.94 -

R

398.22 398.22 398.22 398.22 398.22 398.22 398.22 398.22 398.22 398.22 398.22 398.22

COMd

364.90 364.90 364.90 364.90 364.90 364.90 364.90 364.90 364.90 364.90 364.90 364.90

(RCOMddk)*(1t)+dk

30.76 33.21 30.59 29.01 29.01 27.85 26.66 26.66 26.66 26.66 26.66 34.85

Cash Flow (Nondiscounted)

Cash Flow (discounted)

Cumulative Cash Flow (discounted)

(1.00) (40.96) (30.72) (64.42) 30.76 33.21 30.59 29.01 29.01 27.85 26.66 26.66 26.66 26.66 26.66 69.55

(1.00) (37.24) (25.39) (48.40) 21.01 20.62 17.27 14.89 13.54 11.81 10.28 9.34 8.49 7.72 7.02 16.65

(1.00) (38.24) (63.62) (112.02) (91.02) (70.40) (53.13) (38.24) (24.70) (12.89) (2.61) 6.73 15.23 22.95 29.97 46.62

Cumulative Cash Flow (Nondiscounted) (1.00) (41.96) (72.68) (137.10) (106.34) (73.13) (42.54) (13.52) 15.49 43.34 70.00 96.66 123.32 149.98 176.64 246.19

Cash Flow Diagram (Discounted) Project Value (miliones of dollars)

60 40 20 0 -20

0

2

4

6

8

10

12

14

16

-40 -60 -80

-100 -120

Project Life

Figure 133: Cash flow diagram (discounted).

243

Cash Flow Diagram (Non-discounted) Project Value (miliones of dollars)

300 250 200 150

100 50 0 -50

0

2

4

6

8

10

12

14

16

-100 -150 -200

Project Life

Figure 134: Cash flow diagram (non-discounted).

Profitability Analysis

Net Present Value:

Cumulative Number of Data Points

1000

750

500

250

0 -300

-200

-100

0

100

200

300

Net Present Value (millions of dollars)

Figure 135: Cumulative number of data points vs net present value.

244

Discounted Cash Flow Rate of Return

Cumulative Number of Data Points

1000

750

500

250

0 0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

DCFROR

Figure 136: Cumulative number of data points vs DCFROR.

Cumulative Cash Position

Cumulative Number of Data Points

1000

750

500

250

0 -600

-400

-200

0

200

400

600

800

1000

Cumulative Cash Position (millions of dollars)

Figure 137: Cumulative number of data points vs cumulative cash position.

245

Cumulative Number of Data Points

Rate of Return on Investment 1000

750

500

250

0 -40%

-20%

0%

20%

40%

60%

80%

ROROI

Figure 138: Cumulative number of data points vs ROROI.

Payback Period Data Cumulative Number of Data Points

1000

750

500

250

0 0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

PBP (years)

Figure 139: Cumulative number of data points vs payback period.

246

Heat Integration Heat integration is a technique used to integrate heat duties of the process. Also, it is applied to heat exchanger network (HEN) to find if there are possibilities of reducing utilities, and as a result of reducing utilities, the cost of utility’s stream will be reduced. For heat integration, a useful technique used to integrate heat is called pinch analysis.

Pinch analysis is a technique used to find minimum cooling utility (Qc), and minimum heating utility (Qh) that are needed in the process.

Figure 140: Temperature vs Enthalpy for hot and cold composite curve.

Figure 1 shows temperature vs enthalpy for both hot and cold composite curve. This figure is being plotted by first tabulating all inlet and outlet temperatures for hot and cold stream which will allow finally to find the energy targeted value.

247

When pinch analysis method is used, there are some rules that must be obeyed which are: 1. No external heating below the pinch point.

2. No external cooling above the pinch point.

3. No heat transfer across the pinch point.

Figure 141: Cost vs ∆Tmin.

Minimum temperature difference (∆Tmin) can be found by plotting energy, total cost and capital cost. For total cost curve, it is being found by adding energy cost curve to capital cost curve, where ∆Tmin is the lowest value on total cost curve. In petrochemical processes, ∆Tmin is ranging between 10 oC to 15 oC. In propane dehydrogenation process (PDH) a value of 10 oC is assumed for ∆Tmin.

248

Table 145: Hot and cold streams.

Stream Supply Target Name Temperature Temperature C-101 C-102 C-103 C-104 C-105 H-106 H-107 H-108 H-109 H-110 H-111 H-112

K 316.4 259.4 499.4 339.4 419.4 867.7 750.1 633.1 516.1 401.1 428.7 391.6

K 324.7 339.4 573.1 419.4 499.4 750.1 633.1 516.1 401.1 333.1 297.2 286.9

Heat Capacity Flowrate kW/K 173.001 76.717 94.230 70.795 82.723 137.668 126.830 114.297 99.954 84.330 90.199 102.951

Heat Flow kW 1435.9058 6137.3587 6944.7598 5663.593 6617.8733 16189.7803 14839.11 13372.7361 11494.6606 5734.4686 11861.1935 10779.0084

Stream Type

Supply Shift

Target Shift

COLD COLD COLD COLD COLD HOT HOT HOT HOT HOT HOT HOT

°C 48.3 -8.8 231.3 71.3 151.3 589.6 472.0 355.0 238.0 123.0 150.6 113.5

°C 56.6 71.3 305.0 151.3 231.3 472.0 355.0 238.0 123.0 55.0 19.1 8.8

In table 7, hot and cold stream have been listed with their supply and targeted temperatures.

Heat flow also has been calculated for each stream, and streams have been classified as hot or cold stream.

Figure 142: Composite curve.

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Table 146: Grid diagram.

Grid diagram shows information of each component such as supply and targeted temperatures which are presented by arrows. Also, stream classification as hot or cold stream is mentioned for each stream. Finally, heat flow (Kw) is measured for each steam

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Conclusion To sum up, this project is aimed to develop a process to produce propene via propane dehydrogenation using LPG as a feedstock. Moreover, the reaction conditions for this process are (500 – 650 °C) and (0.5 - 3.5 bar). Also, this project was developed on five stages (chapters).

In the first chapter, an initial PFD was formed, safety and hazards of the materials related to the process were investigated. In addition, a primary calculation related to the profit margin were performed and an alternative process was provided.

In the second chapter, a detailed mass and energy balance were performed for the whole process. Also, a purity of 99.5%, selectivity of 80% and a capacity of (400-455 KT/year ) were achieved for the propene.

In the third chapter, aspen HYSYS was utilized to simulate the PFD in order to provide information, conditions and properties for each equipment to help in the next chapter in which each equipment was designed based on the data obtained from aspen HYSYS. In the fourth chapter, the steps for designing the reactor , distillation columns , heat exchangers, fired heaters , piping , pumps and compressors were provided along with the required tables and figures. Also, the safety and the standards associated with each equipment were discussed.

In fifth chapter which is the final one, an economic analysis and heat integration for the whole process where performed. Moreover, it was found that the process is profitable.

Recommendation The problem statement has been satisfied and all requirements are met. However, additional work is preferable in this process such as studying the alternative ways of dealing with azeotropic mixture presence in T-103 and the applicability of pressure swing distillation or extractive distillation. Moreover, the regeneration system of the catalyst is of concern to utilize the catalyst and to achieve maximum profitability and conversion. Furthermore, the cold stream (refrigerant) used in cooler E-109 and condenser in T-102 is freon. In addition, freon is well known as a potential hazard to the environment, so, an alternative with similar properties should be discovered and substitutes the freon or install a refrigeration system to minimize its hazard.

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Contacts

Address: King Fahad University Petroleum and Minerals (KFUPM), Dharan,31261, Kingdom of Saudi Arabia.

Instructors: Dr. Umer Zahid

uzahid@kfupm.edu.sa

Dr. Eid Almutairi

mutairi@kfupm.edu.sa

DR. Usama Ahmed

usama.ahmed@kfupm.edu.sa

Group members: Asim Algarni

s201626180@kfupm.edu.sa

Dammam

Ali Alamri

s201641820@kfupm.edu.sa

Khobar

Banji Alkhuraim

s201676320@kfupm.edu.sa

Dammam

Mana Aljamhoor

s201624060@kfupm.edu.sa

Najran

Faisal Alasiri

s201671800@kfupm.edu.sa

Dammam

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