www.furnaces-international.com September 2018
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Refractories 6 - Pyrotekâ€™s Insulated Tabletop Refractory helps reduce heat loss 9 - Gouda Refractories expands
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Temperature profiling 12 - Temperature profiling systems support aluminium industry growth 24 - Using CFD and Thermal Modelling to optimise combustion in forge furnaces
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Comment and News
Aerospace specialist gains approval from Rolls Royce in UK Wallwork has secured approval from Rolls Royce at its Cambridge, UK site. The site’s processes including vacuum brazing, plasma nitriding and heat treatment have seen a soaring demand. Simeon Collins, Site Director at Cambridge, UK, said: “Achieving the approval is a great team effort. “Receiving RollsRoyce approval for these processes is vital to the relationship with an important
customer. “It also gives confidence to all our customers that we can meet the exacting standards required by aerospace primes and other precision industries such as motorsport and medical implants/ devices.” The investments will more than double the nitriding capacity at Cambridge. The new nitriders are fully aerospace specified units with a high temperature capacity.
It will also enable quicker processing of aerospace components and increase productivity. Mr Collins added: “The Rolls-Royce approval and these investments mean we go to Farnborough (International Airshow) with an even stronger proposition than in previous years.” Installations include a Seco vacuum brazing furnace and two Rübig and Eltro Plasma nitriders.
Steel manufacturer to restart second Illinois blast furnace United States Steel will restart its second blast furnace at its plant in Granite City, Illinois. The restart of the ‘A’ blast furnace will support the increased demand for American steel and customers during planned asset revitalisation efforts. David Burrit, US Steel President and Chief Executive Officer, said: “After the restart of the ‘A’ blast furnace on or around October 1, all of the steelmaking
operations at Granite City will be back on line. “The restart of the two blast furnaces at Granite City Works will allow us to serve our customers’ growing demand for high quality products melted and poured in the United States.” The steel manufacturer will hire around 300 employees for the restart of blast furnace ‘A’ that will support increased shipments beginning in the fourth quarter. US Steel is also in the
process of restarting a blast furnace ‘B’ at the same site, which will create 500 positions. Mr Burrit said: “Our restart efforts would not be possible without our talented team at Granite City Works. “Thanks to their passion and resolve, we are on track for a successful and safe restart of blast furnace ‘B’, and the forthcoming restart of ‘A’ will be no different.”
Welcome to the September 2018 issue of Furnaces International. Not to rub it in, but we had a wonderful summer in the UK this year! It seems to be continuing into September and the warm weather is keeping us in high spirits as we move into ‘event season’. The aluminium industry in particular will be gathering in Düsseldorf in October for the ALUMINIUM 2018 Show, which will present heat treatment and melting solutions for manufacturers in this sector. Heat treatments are key steps in the production of optimum materials and this show will highlight these technologies, as well as looking towards the future. Today’s foundry industry is being shaped by accelerating technological developments, with megatrends including autonomous driving, electromobility, 3D printing, Industry 4.0, the shortage of specialists and globalisation all having a major impact even as they simultaneously create new market opportunities. Stay tuned to Furnaces International for updates on all things digital! Nadine Bloxsome Editor, Furnaces International firstname.lastname@example.org 3
Furnaces International September 2018
Canadian technology specialist wins furnace award Hatch has won the Metsoc Innovation Award for furnace inspection and monitoring technology. Hatch has received an Innovation Award from the Canadian Institute of Miningâ€™s (CIM) Metallurgy and Materials Society (MetSoc) for its Acousto Ultrasonic-Echo (AU-E) Non-Destructive Testing technique.
The award recognises the Canadian technology specialistâ€™s development in the metals industry and improved technology practice. The AU-E technology uses stress wave reflections to provide insight into the condition and thickness of a furnace wall and refractory lining. Its benefits include cost and safety.
This provides operators with an accurate, real-time understanding of the condition of the furnace, and can proactively identify areas that require repair. Periodic AU-E inspections can be used to plan and prioritise better furnace maintenance and shutdowns, prolonging furnace campaign life and reducing unwanted downtimes.
Picture caption: The non-destructive testing group, winners of the 2018 MetSoc Innovation Award. Top row (L-R): Brycklin Wilson, David Chataway, Peter Szyplinski, Blair Climenhaga Bottom row (L-R): Mitchell Henstock, Afshin Sadri, Viken Koukounian
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US precision specialist invests in quench furnace Peters’ Heat Treating has invested in a quench furnace at its headquarters in Meadville, Pennsylvania. The precision parts specialist has expanded its production capacity with a UBQ (Universal Batch Quench) integral furnace from AFC-Holcroft. Tracy Dougherty, Sales Manager at AFC-Holcroft, said: “This investment shows the continued commitment by Peters’ Heat Treating to invest in the
latest technology and we’re excited to be a part of it.” The furnace equipment will be integrated into an existing UBQ line, which was also from AFC-Holcroft. This will add an additional 3,500 pound gross load capacity to the existing line. The latest UBQ furnace will interface with existing tempering furnaces, spraydunk washer, automated transfer cars, an EZ series endothermic gas generator
Furnace manufacturer to design automotive mesh system CAN-ENG Furnaces International has been contracted to design and commission a furnace system for an automotive supplier. The manufacturer was selected to design a Large Capacity Fastener Hardening Furnace System for a Tier 1 automotive supplier based in Detroit, Michigan. This contract was the result of successfully delivering multiple systems to the automotive supplier over 20 years. It supports the capacity increases for the fastener manufacturer, which offers wire processing, heat-treating, coating and packaging services. CAN-ENG Furnaces International will design and commission a complete high quality automotive fastener hardening furnace system. It will closely integrate a computerised part tracking and metering system, pre-washer, mesh belt hardening furnace, oil quench system,
post washer, temper furnace, soluble oil system, endothermic gas generator and a level 2 automation system. The contracted system is engineered to produce at a rated capacity of 6000 lb (2700 kg) per hour. Its customers continue to enjoy the benefits associated with time-tested Mesh Belt Furnace designs, which promote soft loading and handling features that minimise part damage and mixing potential. Custom designs provide energy efficient alternatives to forward-thinking users that are focused on the lowest cost of ownership procurement. The customisation includes reduced energy consumption heating systems, reduced atmosphere consumption, improved system maintainability and useful service life. The project is currently being processed through manufacturing and is planned for commissioning in 2019.
Refractory manufacturer acquired for expansion in Holland Gouda Refractories has been acquired for further expansion and development in Gouda, Holland. An agreement has been reached by Gouda City Council to acquire Gouda Refractories. This includes the 15000m2 adjacent land and buildings. The construction of a fully automatic mixing line for high-grade refractory
materials is due to start at the end of November 2018. Construction works for a head office are also due to start soon and are scheduled for completion in mid-2019. Other projects include laboratory facilities for product development and further improvements to the production and logistics process.
and other companion equipment. It also offers the flexibility to heat treat a range of parts and a number of metallurgical processes. Peters’ Heat Treating has also invested in a 1400°F gas fired UBT temper furnace for its facility in McKean, Pennyslvania. It has continued to make investments in furnace technology to expand its production capability and gain entry into new markets.
Korean manufacturer invests in aluminium heating plant Ilsim Almax has invested in a heating plant from technology specialist IAS for aluminium extrusion billets. The South Korean manufacturer has ordered a TEM-PRO Heater System from IAS. This will enable the company to heat aluminium extrusion billets for the production of thin-walled aluminium heat exchanger tubes. In contrast to comparable plants, the TEM-PRO Heater attains higher productivity of up to 15%. The temperature profile heating systems allow for precise temperature control and an accurate manufacturing process during isothermic extrusion. Its process control and high flexibility outclasses the gas furnace and conventional induction furnaces. A multilayer coil version and infinitely variable output control ensure low energy consumption.
Furnaces International September 2018
Pyrotek’s Insulated Tabletop Refrac Base-insulated refractory product maintains dimensional stability during VDC billet casting
SPOKANE, WASHINGTON, USA— August 2018—Pyrotek’s base-insulated tabletop refractory for vertical direct chill (VDC) billet casting reduces heat loss and maintains dimensional stability throughout casting tables. “This is a robust solution for VDC billet casting customers,” says Jonathan Klesch, a global product manager for Pyrotek. “We use an innovative refractory and integrate an insulation layer to provide long service life while reducing heat loss across the table.” With this new technology, a microporous board is added to the base of refractory shapes, improving the thermal performance. Casthouses can potentially
lower furnace temperatures by reducing the temperature gradient across the length of the table. Klesch says one of Pyrotek’s core competencies is manufacturing refractory shapes. It produces components for major casting equipment manufacturers and those who rebuild VDC billet casting tables. “We are constantly in search of improving performance and embarked on this product development project to reduce heat loss in billet casting tables without compromising the integrity of the assembly,” he says. Pyrotek’s refractory is a thermally shockresistant material that is nonwetting to
molten aluminium. When compared with a traditional fused silica refractory, the density is lower and strength is higher. This improves both thermal performance and fracture resistance. Field testing has demonstrated a 25 percent reduction in tabletop metal structure temperatures compared to another product on the market. This translates to an estimated 8 percent reduction of heat loss using the baseinsulated design. Trial testing also revealed that a competitor’s product was two-and-a-half times more likely to crack after 600 casts. The smooth surface created by a unique surface treatment system minimizes
6 Furnaces International September 2018
ctory Helps Reduce Heat Loss mechanical attachment of skull and improves wear and erosion resistance. It also had 11 percent lower thermal expansion, reducing stress that developed in the mastic joints between components and led to less maintenance during tests. Pyrotek makes a variety of precast components used to distribute molten metal to mould positions in VDC billet casting tables. These components are preﬁred and ready to use. Along with baseinsulated tabletop refractory, Pyrotek offers monolithic and shell-insulated tabletop refractory. Pyrotek offers all products needed to operate and maintain VDC billet casting tables, including thimbles, transition plates, mastics, gaskets and seals, ﬂowcontrol products, coatings and lubricants and casting accessories.
Automatic Heat Treatment Line Profitherm P80, Austria, 2017
Laboratory furnaces 1100–1600°C
Chamber furnaces 600–1100°C
Industrial ovens 250-400°C
Heat treat furnace 1050°C with quenching tank Retort furnace 650°C with controlled atmosphere
Furnaces International September 2018
More even heating. Even more heating performance. Boost your reverb furnace performance with the Transient Heating oxy-fuel burner. With Air Products’ patented Transient Heating burner, you can achieve more even heating throughout your reverb furnace, eliminate cold zones, and maximize melt rates. How? It is the only smart burner technology in the world using a sensor-driven control strategy to direct energy down toward the melt; sequentially to all areas of your furnace. This innovative technology can help you realize: • Up to 40% increased productivity • Up to 40% improved fuel efficiency • Up to 20% higher metal yield
Give us a call today to get even more out of your reverb furnace! +44 800 389 0202
tell me more
© Air Products and Chemicals, Inc., 2018 (41829)
Gouda Refractories expands An agreement for the acquisition of 15.000 m2 of adjacent land and buildings has been reached with the city council of Gouda. With this acquisition the ambitions and further development of Gouda Refractories can be realised.
The construction of a new fully automatic mixing line for high-grade refractory materials will already start at the end of November 2018. Construction works for a new head office will start soon and are scheduled for completion by mid-2019. Other projects that can be realised through this expansion include the realization of cutting-edge laboratory facilities for product development and further improvements to the production process and logistics process.
Gouda Refractories BV Established 117 years ago in Gouda and strategically located at the riverside close to the port of Rotterdam, Gouda
Refractories is a former stock-exchange listed company with two premises in Gouda and Geldermalsen. Gouda Refractories became part of Andus Group in 2008 and focuses on the design, engineering, manufacturing and supply of high-grade refractory linings (bricks, castables and prefabricated elements) which are used in various critical industrial installations worldwide. Within this specialist market, Gouda Refractories has a leading position with worldwide clients in a.o. the Non-Ferrous Metals, Petrochemical, Energy, Steel, Raw Material Calcination and Waste Treatment Industries.
Andus Group BV Andus Group is an enterprise with 13 independent subsidiaries in the Netherlands, Belgium, Germany and Slovakia. These companies mainly operate in the field of process equipment, offshore platforms, industrial castings, ship propellers, rail infrastructure, travellerrelated facilities, refractory bricks and linings and complex steel structures. The markets Andus Group mainly operates in are the (petrochemical) industry, infrastructure and the maritime sector. The group has an annual turnover of more than 200 million euro and over 800 employees.
Furnaces International September 2018
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Novel melting technology for reverb furnaces Conventional sidewall-fired burners direct energy into open spaces within a furnace and radiate energy in all directions. Energy is radiatively transferred directly (flame to the aluminium) and indirectly (flame to the refractory and then refractory to the aluminium). The energy input into the process is typically controlled by a thermocouple that is positioned in the roof of the furnace. This means the rate of overall energy input is determined and limited by the maximum allowable surface temperature of the refractory. An ideal system would preferentially channel the energy to the metal (relative to the refractory) via direct flame impingement. This, however, increases the potential for localised overheating and risk of oxidative melt losses. The Transient Heating oxy-fuel burner (THB), a novel melting technology, uses zonal temperature sensors and flame movement to 1) direct energy preferentially to the aluminium, and 2) provide needs–based, sensor–driven, superior spatial and temporal energy distribution in the furnace in order to minimise overheating and aluminum oxidation. Results such as 48% decrease in specific fuel consumption, 35%
improvement in productivity, and 20% reduction in melt loss have been achieved compared to baseline air–fuel operation. The THB technology is based on transferring heat from the flame to the melt charge via radiation and direct flame impingement (DFI) to provide heat when and where it is needed in the furnace. The THB is usually mounted on the furnace roof and typically has four nozzles directed toward four quadrants of the furnace below the burner. Using proprietary control techniques, coupled with temperature feedback, the burner can direct heat to any combination of the quadrants; delivering the efficiency benefits of DFI while avoiding overheating by limiting the firing in any one direction. When installed in a reverb furnace, THB helps to: � Prevent overheating and nonuniform temperature distribution by delivering heat to where it is needed in the furnace. � Prevent oxidation and melt losses by creating a reducing atmosphere near the melt. � Minimise NOx generation by lowering flame temperature via staging of fuel and oxygen.
Furnaces International September 2018
Temperature profiling systems supp aluminium industry growth By Dr Steve Offley*
*Product Marketing Manager, PhoenixTM
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In today’s manufacturing market aluminium is increasingly becoming the material of choice being lighter, safer and more sustainable. With estimated growth in global aluminium demand in 2018 of 4-5% both primary and secondary processors of aluminium are rapidly looking to improve the efficiency of their operations. Manufacturers looking to replace existing materials with aluminium are needing new methodology to prove that new thermal processing of aluminium parts and products is done to specification, efficiently and economically. Helping with this need PhoenixTM offers a range of Temperature profiling solutions designed specifically for applications in the Aluminium manufacturing market. Whether reheating aluminium slabs/ingots or log homogenisation in a continuous pusher or walking beam furnace, solution reheating (T6) aluminium automotive parts, CQI-9 & AMS2750 TUS, CAB brazing radiators or powder coating aluminium extrusions a unique system solution is available. In many situations PhoenixTM has worked directly with key industry players to develop bespoke solutions for unique process challenges.
PhoenixTM Temperature Profiling Solutions
The PhoenixTM temperature profiling system is designed to travel through the thermal process measuring the product and or furnace environment. A safe, efficient alternative to traditional trailing thermocouples. A high accuracy, waterproof, multichannel datalogger records temperature from thermocouple inputs, located at points of interest on, in or around the product being thermally treated. To protect the datalogger as it travels through the hostile furnace a thermal barrier ‘Hot Box’ is employed to keep the logger at a safe working temperature to prevent damage and ensure accuracy of measurement. The design and choice of barrier is strongly influenced by the demands of the process as illustrated later in the article (Aluminium Processing Solutions). PhoenixTM prides itself on offering the most comprehensive, flexible and durable range of barriers to suit, even the highest of temperatures and longest soak times, hostile environments whether pressure, gases or quenches, and process challenges such space limitations, product rotation
or automatic robotic handling systems. Employing the PhoenixTM system a complete thermal record of the product throughout the entire process can be collected. A popular enhancement to the system is the use of 2-way RF telemetry providing real time process monitoring direct from the furnace. The product temperature can be viewed live and downloaded at any point in the furnace. Raw temperature data collected from the process can be converted into useful information using one of the custom designed PhoenixTM Thermal View Software packages available. The thermal graph can be reviewed and analysed to give a traceable, certified record of the process performance. Such information is critical to satisfy CQI-9, AMS2750 and other regulatory demands. Fully TUS compliant reports can be produced in moments from the simple and intuitive software, making accurate TUS a simple and quick task. Information can be used to not only prove product quality but provide the means to confidently change process characteristics to improve productivity and process efficiency (Optimise Soak Temperatures & Times).
PhoenixTM Datalogger Range Dataloggers can be provided in a variety of configurations to suit the specific demands of the process being monitored. Models ranging from 6 to 20 channels can be provided with a variety of thermocouple options (types K, N, R, S, B) to suit measurement temperature and accuracy demands (AMS2750 & CQI-9). The loggers can be offered in either standard (<80°C/176°F) or high temperature operating temperatures (Barrier Core Temperature <110°C/230°F) variants to allow use of either standard thermal barrier designs (Dual Phase Heat Sink) or high performance (Phased Evaporation – Water Tank). Built to cope with hostile industrial environments the IP67 logger is capable of managing even the most demanding water quench process. Provided with Bluetooth wireless connection for short range localised download and reset (direct from within the barrier) the logger memory of 3.8M allows even the longest processes to be measured with highest resolution to deliver the detail you need. An optional unique 2-way telemetry package offers live real time logger control and process monitoring with the benefits detailed in the following section.
Furnaces International September 2018
Figure 1. PhoenixTM PTM1220 20 Channel IP67 Datalogger
TXR-1000 PTM logger
Figure 2. Schematic of RF Telemetry Real Time Monitoring Network
Live Radio Communication The logger is available with a unique 2-way RF system option allowing live monitoring of temperatures as the system travels with the product through the furnace. Furthermore, if necessary using the RF system it is possible to communicate with the logger, installed in the barrier, to reset/download at any point pre, during and post-run. Provided with a high performance ‘Lwmesh’ networking protocol the RF signal can be transmitted through a series of routers linked back to the main coordinator connected to the monitoring PC. The routers being wirelessly connected are located at convenient points in the process to capture all live data without any inconvenience of routing communication cables as needed
on other commercial RF systems. The operator from the convenience and comfort of his control room/office can see what is happening in the process live. For an 11 hour process such live data gives the operator confidence that process is working without that nervous wait with a non-RF system to download from the logger at the end of the run. In many processes there will be locations where it is physically impossible to get a RF signal out of the furnace. With conventional systems this results in process data gaps. For the PhoenixTM system this is prevented using a unique fully automatic ‘catch up’ feature. Any data that is missed will be sent when the RF signal is re-established guaranteeing in most applications 100% in-process data review.
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Aluminium Processing – Bespoke Thermal Barrier Solutions
Figure 3. A and B. PhoenixTM System embedded in aluminium slab/Ingot stainless steel cover to protect from high velocity air ﬂow in furnace
Preheat of Aluminium Slabs/Ingots prior to Hot Rolling (Pusher Furnace) Thermal Barrier embedded into the slab (machined or milled out) to allow safe transit of the test slab through pusher furnace (Typically 550°C/1022°F). Thermocouples set deep into the core of the slab/ingot. Water tank designed to give capacity (volume of water) to allow protection of logger running safely at 100°C/212°F as water boils and evaporates off. Filling mechanism designed so that even during slab rotation (180°) entering and exiting furnace water is not lost from the tank. Employing RF, the soak process can be monitored to ensure that the correct rolling temperature is achieved
to avoid excessive roll wear. From live monitoring halving of soak times have been achieved.
Aluminium Log Homogenisation (Walking Beam Furnace) After casting aluminium logs are homogenised before being supplied to extrusion companies. The walking beam process is demanding not only due to the excessive durations (12 to 13 hours at 580°C/1076°C) but the fact that the profiling system has to rotate with the log and therefore needs to be the same form as the log with the same diameter or less. The PhoenixTM rotating cylindrical barrier design meets the demands of the process perfectly. The barrier is attached to a shortened log and thermocouples are routed along the log in a machined
Furnaces International September 2018
Figure 4. PhoenixTM Cylindrical Rotating Water barrier fixed to the aluminium log
channel to prevent problems during movement through the furnace. Design of the barrier water tank, providing thermal protection, guarantees that water capacity is maximised with no loss of water during continuous process rotation.
T6 Solution Reheat of Aluminium Automotive Products (e.g.: Alloy Wheels, Cylinders) The solution reheat process (T6) comes with many technical challenges where temperature profiling is concerned. The need to monitor solution treatment, quench and then the age hardening process requires not only a system that will protect against heat over a long process duration but also withstand the rigors of being plunged into a water quench between the two heating phases. The PhoenixTM HTS06 system has been designed specifically for the T6 process. The Datalogger is installed in the water tank cavity of the thermal barrier, with a water tight seal comprising of heavy duty gaskets and compression glands, through which the thermocouples exit. This protection along with the loggers IP67 rating ensures that the logger is protected from water damage during the quench. Providing significant thermal protection, the outer cage containing the thermal insulation blanket wrapped water tank is capable of running through all three processes without interruption. In the quench the water tank is replenished and the blanket will absorb water providing further protection during the age hardening process. The TS06 can provide protection at 550°C/1022°F for up to 20 hours. A key benefit of the TS06 system is the option to monitor with Real Time RF. Live process data can be viewed through the entire process. Although an RF signal cannot escape from the quench the unique ‘Catch Up’ feature allows this data to be transmitted once the system enters the ageing furnace. Monitoring the quench rate and time after solution treatment and before quench is critical to guarantee the correct material characteristics. Increasingly with a move to robotic handling in rotary T6 basketless furnaces, where space is even more critical and automatic handling of barriers becomes essential further new barrier solutions have been needed. The ‘Humpback’ barrier shown is an adaptation of the
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Fig 5. A and B. PhoenixTM HTSO6 Solution Reheat System and Temperature Profile Trace collected from system
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Figure 6. PhoenixTM Humpback T6 barrier designed for robotic handling in automatic Rotary furnaces
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Figure 7. A and B. Unique PhoenixTM CAB Brazing System Design with contamination free profiling capability
Furnaces International September 2018
Figure 8. A and B. PhoenixTM finishing system showing PTM1220 20 channel logger with traditional magnetic thermocouples used on steel body shells. New aluminium clamp probe used on car bodies with aluminium sections (door skin, roof or hood).
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Figure 9. (A) PhoenixTM Compact Finishing System showing PTM1006 6 channel logger and
(B) Clamp probe fixed to an aluminium extrusion (C) Phoenix TS01 system in Batch Age Hardening Oven
9C 21 www.furnaces-international.com
Furnaces International September 2018
TS06 system. Utilising the water tank thermal protection principle, the cage containing thermal blanket is replaced by a microporous insulation skin and robust outer stainless-steel case. The resulting barrier can be shaped to allow the barrier to be picked up by robotic clamps as part of automatic transfer into either furnace or quench process.
AMS2750/ CQI-9 Furnace Temperature Uniformity Surveys (TUS) Complimenting the range of product profiling solutions PhoenixTM is able to offer fully AMS2750 and CQI-9 compliant Temperature Uniformity Survey (TUS) solutions. Combining the thermal barrier or external logger offerings the system can be used to validate that the furnace set-points defined in the TUS are within specified limits. The Thermal View Survey Software package provides full review, analysis and reporting to satisfy the strict requirements of regulatory standards.
Aluminium Brazing (CAB & Vacuum) Monitoring controlled atmosphere brazing (CAB) processes used in the manufacture of radiators and condensers although not a thermally demanding application, compared to others discussed, it does come with its own specific challenges. Mesh belt furnaces often have limited access requiring the use of low profile barrier designs. Chemicals in the flux used in the process create Hydrofluoric acid which can chemically attack the glass cloth used in most thermal barrier constructions. To overcome this issue the CAB barrier is designed with a front-loading draw as shown to minimise the amount of exposed cloth. As its name suggests the CAB process can in some cases be compromised by the degassing of oxygen from the barrier.
To eliminate such problem the barrier insulation is pre-treated with a vacuum heated/nitrogen purge procedure. A further option is available for use just prior to the profile run where a nitrogen purge can be performed to remove remaining air from internal insulation and logger cavity.
Paint Cure on Aluminium Car Bodies With the drive for fuel economy and tighter emissions controls automotive manufacturers are moving away from tradition steel to lighter aluminium. With this move there is ever more need to profile the paint process to ensure that the various coating chemistries (E-coat, Primer Surfacer, Top & Clear Coat) are cured correctly to give both physical protection and cosmetic appearance. The PhoenixTM Finishing system allows the cure process(es) to be monitored accurately. To address the new challenges of aluminium door skins/ roof panels and hoods an alternative thermocouple was needed to replace the traditional magnetic thermocouple. The unique aluminium clamp probe allows quick, efficient and accurate probe placement into the body shell.
Age Hardening & Powder Coating of Aluminium Architectural Products Aluminium plays a large part in the architectural market. Aluminium extrusions are commonly used in the manufacture of window, door and other architectural products. As part of the manufacturing process the extruded aluminium profile needs to be artificially age hardened. This process is essential to ensure ultimate tensile strength and yield strength and requires that the product is
soaked at typically 185Â°C/365 Â°F for 4-5 hours. Measurement of the load core in the ageing furnace is critical to ensure consistency of product ageing throughout the batch. To monitor such processes the PhoenixTM TS01 system is perfect at allowing product temperature readings over the oven void without need for training thermocouples. The same system can be used to survey the oven (TUS) to validate temperature distribution without product. The final manufacturing step for the extrusion is the powder coating to give protection against the elements and control surface cosmetic characteristics. To protect against, coating life time guarantee warranty claims, applicators often are required to supply coating suppliers with evidence of product curing performance. Accredited applicator schemes will require that production runs are certified with a profile trace showing that the powder coated product achieved the correct Time @ Temperature. The PhoenixTM Compact finishing system is the perfect tool for monitoring such processes. Whether an applicator or coating supplier the system is portable, easy to use and provides the certified traceable documentation needed for process validation and quality assurance.
Conclusion PhoenixTM offers complete, reliable in process temperature profiling solutions, for use across the aluminium processing industry. Offering unique solutions to meet the specific application challenges PhoenixTM provides, tried and tested systems, used globally by key market players to understand, control and improve their manufacturing operations.
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Applying Industry 4.0 to the aluminium industry Aluminium manufacturers are constantly looking to improve the efficiency of their production processes and are relying upon increasingly sophisticated digital technologies to streamline their operations. In such a fast-moving world, characterised by complex Internet-based manufacturing systems, Future Aluminium Forum 2019 is a must-attend event for aluminium professionals who want to unravel the mysteries and get to grips with the complexities of Industry 4.0. This international technology conference will draw upon the unrivalled expertise of aluminium industry professionals, production technologists and academics, to create an event designed specifically for those seeking a greater understanding of ‘smart manufacturing’. The canvas will be broader, the net spread wider and other linked topics – such as 3D printing, artificial intelligence, automation, robotics, and ‘social product development’ – will be high on the agenda. The Future Aluminium Forum is a live discussion that will examine how Industry 4.0 and digitalisation will revolutionise aluminium manufacturing and analyse the benefits that can be gained from doing so. Expect lively conversation, animated discussion panels and plenty of networking opportunities in Warsaw, Poland on 22-23 May 2019. TO SPONSOR/EXHIBIT: Ken Clark International Sales Director +44 (0) 1737 855 117 email@example.com
Nathan Jupp Sales Manager +44 (0) 1737 855 027 firstname.lastname@example.org
TO SPEAK: Nadine Bloxsome Programme Director +44 (0) 1737 855 115 email@example.com
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Using CFD and Thermal Modelling to optimise combustion in forge furnaces By Michael Cochran*
Maintaining desired operating temperatures with good uniformity is essential in optimising product quality in Forge Furnaces. Factors such as the combustion control strategy, burner placement, location of flue, material height, and burner capacities all influence furnace performance. Thermal modelling can be utilised to determine the required capacity or input into the furnace. Combining thermal modelling with CFD modelling can provide a more complete picture in the design of the combustion system, including correct placement and quantity of burners and flues, for optimal efficiency and uniformity. Upfront modelling should be viewed as
part of an overall project risk management analysis. Benefits to optimising combustion systems through modelling include improved product quality, fuel savings, and reduced emissions. The paper/presentation will serve to educate the audience on the benefits of using these modelling tools in the design and revamp of Forge Furnace combustion systems. It will also provide a field Case Study that will show simulations and results for a forging application. Many forging applications bring the product to temperature in a batch style furnace (generally in a car bottom, or fixed hearth arrangement) using combustion as the source of the heating
Temperature vs. time 10 tons
furnace temperature Average steel temperature External steel temperature Internal steel temperature Differential steel temperature
1000 500 0 0
Required heat [MMBtu/hr]
energy. When designing a new furnace, the combustion engineer often has the relevant information about the pieces that require forging, as well as temperature requirements at the end of the process, and must determine the proper design of the combustion system including thermal input, burner location and sometimes flue or door locations. While relevant experience can guide the process, a proper model is crucial for the correct solution to ensure optimal performance. The modelling is typically a two-step process consisting of (1) a thermal model and (2) a Computation Fluid Dynamics (CFD) model. This paper will describe the general steps in developing the model,
Required heat vs time 10 tons
4.0 Margin HHV
3.0 2.0 1.0 0.0
600 Time [min]
9 10 11 12 13 14 15 16
Time [hr] Figure 2
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and will explore a specific example of a forge furnace and the models applied to it.
CFD analysis will show the best solution for the forge furnace being designed.
The purpose of the thermal analysis is to determine the proper sizing for the combustion system. Knowing the load, piece size, furnace size and heating practice, the proper sizing of the system is possible. As described in this paper, the piece size and load as well as time and temperature curves are known, and the thermal input is determined. (It is also possible to reverse the process, and determine the heating cycle based on a given input. But this process is outside the scope of this paper, and can be very difficult to do properly.) There are several furnace modelling software packages available for the purposes of determining the thermal input. It is also possible to use general modelling software tailored to the specific application, but furnace modelling software is common, and there are packages priced to fit many budgets. Depending on the level of sophistication, most modelling packages can run on a standard laptop computer. At its most basic, the thermal model will provide a heating curve and an energy use summary. Figure 1 shows a sample curve for a simple heating practice. This sample shows the furnace temperature and product temperatures as a function of time. (Note that the product in this model is relatively small in physical size, which is apparent because the differential through the piece does not get too large.) These product and furnace temperatures, in combination with basic combustion
A forge furnace and its combustion system are designed for a specific process. Before determining the right combustion solution, it is important to have accurate information on this process. The required information includes: � Piece size and shape � Material grade (titanium, carbon steel, stainless steel, etc.) � Total load on the hearth � Temperature profile—generally as a ramp (or ramps)/hold curve � Furnace dimensions and refractory specifications Unless these basic data are welldefined, any resulting solution will be at best guesswork. While a forge furnace may process several different materials or piece and load sizes, it is important to design the combustion system for the most aggressive requirement. Although identifying that case is not always straightforward, it is typically the largest total load in the furnace, and/or the most aggressive ramp rate. The modelling engineer can determine which is the most aggressive case, as long as he or she has complete information about all possible heating scenarios expected of the furnace.
Modelling the furnace After establishing the process characteristics as defined above, complete engineering analysis of a forging process including both thermal modelling and
The thermal model
parameters such as fuel type, then determine the energy requirement of the furnace. A sample energy use chart appears in Figure 2. There are many ways to visualise the energy requirement. A common unit of measuring burner power is in MMBtu per hour. Therefore, in this sample, the total energy required in an hour (including heat to the product as well as other process requirements and lost heat in the flue gases) is totalled in each bar on the chart. That is, each bar on the chart represents the total energy (in MMBtu) required as predicted by the model. It is then a simple task to choose the highest bar, and select that as the required capacity for the system. (In other words, size the system for the hour that sees the most energy demand.) The thermal modelling will determine the amount of heat required for the process, but can say very little about the distribution of the heat within the furnace structure.
The CFD analysis With the combustion system sizing complete, a CFD analysis is in order. While the thermal analysis determines the bulk input heat to the process, as well as the sizing of auxiliary components, the CFD analysis is useful for determining correct number and placement of burners and/or proper placement of flues based on the furnace and door configuration. In contrast to the thermal analysis, which looks at the entire furnace and determines total thermal input, the CFD looks at the physical space within the furnace and determines the process values at locations within the space. Furthermore, the
Furnaces International September 2018
computing power required for a proper CFD analysis typically exceeds that of a standard office computer, and often requires significant experience to setup, perform, and interpret the model. CFD divides the physical space within the furnace into a grid (or mesh) of points then solves relevant chemical and fluid equations for each point in the mesh, thus determining values such as temperature, pressure, and fluid velocity at those points. With the solution to the equations set at one time, it is possible to solve these equations for the next time step as well. In that way, the fluid and chemical characteristics at each (physical) point, and each time are available to the engineer to design the system. One of the beauties of CFD is that it is easy to change a parameter in the system with a few keystrokes, and thus see what effect that parameter has on the performance of the system. (For example, altering the position of a burner in the model will easily show the effect on the whole system.) Making these alterations allow the engineer to determine correct placement of burners to achieve the proper temperature uniformity within the heating chamber. Figure 3 shows a CFD model of a flue for a forging furnace. Here we see the temperature of the waste gas at all points in the flue. As you can imagine this level of detail would not be available in a physical test of a flue. For a physical test, temperatures at only a finite number of locations would be available, perhaps missing some of the crucial physics of
the arrangement. Also, it is not a difficult exercise to change, for example, the height or diameter of the stack in order to see the effects on the behaviour of the furnace.
Case study Though many forge furnaces are box style or car bottom, a customer wanted to use a rotary furnace for a forging application. Because this approach was so unique, there weren’t ready rules or thumb, or past experience to guide the placement and number of burners. Therefore, proper modelling of the process was critical. Bloom Engineering completed both a thermal model and CFD model. The thermal modelling (i.e. determining bulk input to the system) was reasonably straightforward. The question of distributing that input through the furnace was not. The questions of how many burners to utilise, and how to orient them in the furnace required complicated analysis. The CFD modelling, was quite detailed requiring several iterations to converge on the proper solution. The full model included both the volume of the furnace, as well as modelling the product within the furnace, as seen in Figure 4, which shows the physical structure, preliminary placement of the burners and location of the product (vertically set rounds). After modelling the physical furnace space, Bloom’s thermal engineer made an educated guess about the number, location and orientation of the burners based on the total furnace input. This first
effort proved to be inadequate. Figure 5 shows that the original solution caused significant hot spots in the furnace that would lead to improper product heating. After a few iterations, a satisfactory solution (See Figure 6) was found that gave acceptable temperature uniformity (i.e. ±25 °F for the product at the end of the cycle and flame envelope less than nine feet long). It is clear that the overall temperature uniformity is much improved, giving good production coverage, and leading to satisfactory processing. Of course, the whole point of the modelling is to show proper heating of the product (generally inferred from appropriate uniformity of the furnace volume), but an explicit demonstration of product uniformity is useful. Figure 7 shows that there is little variation of product temperature through the furnace.
Conclusion Proper modelling of a forging problem will reveal the correct solution for a forging furnace design accounting for temperature uniformity, waste gas flows, and emissions. A full analysis consists of both a thermal model to determine the total thermal capacity required for the application, and a CFD analysis to determine correct number, placement and orientation of the burners. The modelling tools available determine an optimal solution during the engineering phase, and it is worthwhile to consult with an experienced combustion engineering company to ensure proper design.
*Bloom Engineering Co. Inc. 26 Furnaces International September 2018
The evolution of refractories Prof John Parker* investigates the materials used by glassmakers in the past to construct their furnaces.
Ancient glassmakers needed not only fuels and raw materials but also a furnace to melt their product. They had to build a mechanically stable structure to contain the heat but also needed crucibles to hold their glass melts. The operating temperatures they were able to generate by burning their available fuel and wood, did not exceed 1100°C but the crucibles were exposed to the same fluxes used to melt the principal glass ingredient, sand. These fluxes could attack the furnace structures as volatile species or as dust; ash from the fuel was another source of reactants. These early glassmakers in Syria and Egypt worked alongside metallurgists melting copper, tin, brass and bronze and they also required crucibles and furnaces. There was a co-existing pottery industry that made various vessels and more complex shapes. Now clays have a relatively high proportion of water and so, after first forming, must be carefully dried; much of the water though is chemically bonded and is not lost until the clay is fired above 800°C, when it decomposes with a substantial volume reduction. This shrinkage easily leads to cracking during manufacture, so firing crucibles has always been a slow process requiring extended times at high temperature for equilibration. Additionally, from early times, carefully
selected pre-fired material – grog – was added to the clay to stabilise it. Even clean pieces of broken pots were used, while in more recent centuries silica sand has served a similar role. So early glassmakers had the skills to make small pots a few centimetres high in which they could melt their batches. By the 7th century the technology had developed to the point where these clay pots could be large enough to hold half a tonne of glass. Larger pots were made by coiling a preprepared strip of clay around a circular base and slowly building up the side of the crucible. After reaching the required height, the walls were carefully kneaded into their final shape. More recently covered pots holding a tonne of glass have been made, which involves the glassblower’s iron being introduced through a small opening. Several pots were placed inside a furnace at once; if these crucibles remained hot they could be re-used but the initial manufacturing process was a skilled and slow job – for larger pots it involved puddling the clay for days under foot to remove any trapped bubbles, which could cause the pot to explode during its first firing with dangerous consequences if it already held molten glass. It has been suggested that pot-makers would occasionally make a defective pot deliberately to remind the owners of glasshouses of their importance. Fireclay slabs could also be used for furnace walls but naturally occurring sandstone outcrops were an alternative. In the UK they are found in the English Pennines and were a popular building material used for housing but they were also used by early glassmakers for furnace buildings. The refractories industry began to develop its processing technologies and improve its raw material sources to create better quality materials in the 18th and 19th centuries. Higher firing temperatures allowed the manufacture of bricks with lower
porosities and hence greater corrosion resistance. Siemens’ development in 1870 of regenerative glass tanks, combining both roles of containing heat and the glass melt, also drove change. It followed a trend that had started 100 years earlier, with some 20 patents for tank furnaces having been taken out in the UK during that period. The refractory materials of choice continued to be fireclay or sandstone until the 1930s and, consequently, the furnaces had relatively short lives of a few months. After all, the furnaces were being operated to dissolve silica. Early fireclay refractories belonged to the SiO2-Al2O3 system chemically. At one extreme, silica has a melting point of 1723°C and, at the other, alumina has a higher melting point of 2040°C. Importantly between these extremes a compound called mullite exists with an approximate composition of 2SiO2.3Al2O3 and a melting point of 1810°C, higher than for silica but less than for alumina. Compositions between silica and mullite start to melt at 1595°C (or lower in the presence of impurities) with high silica compositions giving a much greater proportion of liquid at this temperature. The compositions that are most refractory are therefore close to pure silica or have a much higher alumina content. By 1950 most fireclays that were in use in the UK fell in the range 27-41% Al2O3. The naturally occurring sandstone blocks that were also used typically had around 10% Al2O3. Interestingly there is archaeological evidence for the construction of large tanks to melt glass even in ancient times with the material produced being shipped around the civilised world for re-working. Such tanks used a one-month campaign to produce a melt and then were simply demolished to recover the glass.
*Curator of the Turner Museum of Glass, The University of Sheffield, UK www.turnermuseum.group.shef.ac.uk firstname.lastname@example.org 27
Furnaces International September 2018
Electric box furnace
Focus on: Electric Box Furnace For heat treating engine parts in inert atmosphere for a motor manufacturing facility
L&L Special Furnace Co, Inc., has supplied an electric box furnace to a Midwestern engine manufacturer that produces parts for large industrial engines, motor and steam generators.
The furnace has an effective work zone of 22” wide by 18” high by 22” deep, as well as a complete digital control system, overtemperature protection and counterbalanced vertical door for ease of loading. It is used for larger structures that require thermal treatment along with running batches of multiple parts. The furnace is used for hardening and annealing of many varieties of components employed in equipment manufacturing. L&L’s Model XLE244 has an alloy fan that provides excellent uniformity (±10˚F) from 300˚F to 1,800˚F. The alloy roller hearth and movable load table allow for larger heavy parts to be easily moved in and out of the furnace manually. It is equipped with an inert blanketing atmosphere control system. This displaces
oxygen in the system and helps keep the parts from scaling. All L&L’s furnaces can be configured with various options and be specifically tailored to meet your thermal needs. We also offer furnaces equipped with pyrometry packages to meet ASM2750E and soon-to-be-certified MedAccred guidelines. Options include a variety of control and recorder configurations. A three-day, all-inclusive startup service is included with each system within the continental US and Canada. International startup and training service is available by factory quote. If precise temperature control and uniformity is a key to your process, then L&L’s XLE series is a great choice.
Model XLE244 electric box furnace - detail of fan and cast alloy roller rails and tray
28 Furnaces International September 2018
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