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Research Inventy: International Journal Of Engineering And Science Issn: 2278-4721, Vol. 2, Issue 2 (January 2013), Pp 34 - 41 Www.Researchinventy.Com

Effect Of Organic Household Waste Tar Removal By Condensation On The Flue Gas Composition 1, 1,

Subagiyo, 2, Eko Naryono, 3, Sandra Santosa

Mechanical Engineering, State Polytechnic of Malang , Indonesia Chemical Engineering, State Polytechnic of Malang, Indonesia Soekarno Hatta No. 9 Malang

2,3,

Abstract: Condensation is an alternative methods of tar separation on solid waste combustion systems. This research studied the effectiveness of this method to reduce CO, C O2 and hydrocarbon (HC) in the exhaust of combustion gases of household waste with various moisture content. The results showed that the separation of tar does not affect the concentration of CO, C O2 and low boiling point hydrocarbons. From the results of qualitative analysis at condensate, showed compounds like hexana, cyclopentan, phenol, p-cresol and guaiacol, Na, Ca (trace). The concentration of tar was 4.297% analyzed using gravimetric analysis tar, and the ash was 0.449%. Keywords: Gas emissions, Condensation, Combustion, Tar.

I. Introduction Co mbustion is one alternative household solid waste treat ment that produce flue gases and contaminants. Household solid waste has a great volatile matter and water vapor. In the co mbustion process they are becoming a precursor to the formation of volat ile tar and soot (Jinliang, 1996). Tar is one of the contaminants that should be removed fro m the flue gas before it is discharged into at mosphere. This co mponent is a source of particu late matter (PM ) that is harmful if inhaled (Jenkins et al, 1998) So lvent scrubber and thermal destruction are the techniques commonly used in many incinerat ion plants to removed tar and contaminant ( Phupuakrat et al., 2011, Zhang et al., 2010). However, this techniques requires high cost of equipment and also the operating cost so it makes less appropriate when applied on a small scale.Condensation is a simple method of tar separation technique. Theoretically, it can condense tar which has a boiling point above benzene. The water content in the waste affect the rate o f evaporation of volatile materials, condensation and tar composition. When the flue gas was cooled, the tar and other contaminants that can be condensed will separate from the gas so it beco me mo re clean.The information of the effect o f tar removal on the co mposition of flue gases is hard to find fro m the open literature in the recent year. Most of the operated incinerators, recycled the tar to be burned out. On fuels with high water content, this technique is not effective because it affects the continuity of co mbustion This research was studied the influence of the tar removal by condensation on the composition of CO, CO2 and HC in the exhaus t gas of household waste combustion with various water content. The result was analy zed and d iscussed to view of the changes on gas co mposition, gravimet ric tar and fly ash.

II. Methods 2.1. Experi mental Facilities. The experiments were run in a batch process by burning 1000 grams organic household waste (4) in a fixed bed incinerator as shown in Figure 2.1. The incinerator is a vertical cylindrical co mbustion chamber. The height of the chamber is 2.0 m with an inside diameter of 300 mm. The grate (5) is located at the bottom of the chamber and consists of mild steel wire screen. Five thermocouples were used to monitor three temperatures (T1,T2,T3) inside the bed with different height levels, temperature of flue gas and condensing temperature. All thermocouples were connected to a computerized data logger (1) to record the temperatures automatically. There is a gas-sampling probe outside the chamber of the inco ming (3) and out going (9) condenser (8). An LPG gas burner (6) was used on the combustion process to maintain the temperature at 300o C. The day light solar heat was used to vary the waste water content. Waste generated from the drying has a water content of 15.4 (8 days), 24.1 (6 days), 30.2 (4 days) and 40.4% (2 days).Incoming and outgoing gases were measured to be analyzed in order to see the changes of CO, CO2 and HC concentration. The condensate was qualitatively analyzed to see any organic co mpounds, metals, and the concentration of gravimetric tar and ash were measured quantitatively. 34


Effect Of Organic Household Waste Tar Removal By Condensation‌ 1

2 3

T3 T2

Water pendingi n

8 T1

4

9

10 12

5 11

13

7 6 Fig. 2.1. Schematic d iagram o f the experimental setup

1. Temperature Monitor, 2. Feed, 3. Inco ming gas probe, 4. Organic waste, 5. Grate, 6. Burner, 7. Ash, 8. Condenser, 9. Out going gas probe, 10. Tar Tan k, 11. Inlet Air, 12. Exhaust gas, 13. LPG gas

2.2 Gas Analysis And Tar Determination The released gas was analyzed by gas analyzer (Crotech QRO-401), whereas light hydrocarbon species was analyzed using GC/MS spectrophotometer. The concentration of heavy tar and fly ash fro m condensate was measured using gravimet ric method.

III. Result And Discussion 3.1 Temperature Profiles Temperature profiles of co mbustion (T1,T2,T3) can be seen in Figure 3.1a, b, c. It shows that as the mo isture content getting lower, at the same interval t ime, T1 beco me higher. The highest temperatures reached at 15.4% water moisture content. Temperature T1 profile 400 350 300

T(oC)

250 200 Wat er cont ent 15.4%

150

Wat er cont ent 24.1%

100

Wat er cont ent 30.2%

50

Wat er cont ent 40.4%

0 0

50

100

150

200

Tim e (m in)

Fig 3.1a Temperature profil of T1.

T(oC)

Temperature T2 profile 200 180 160 140 120 100 80 60 40 20 0

Water content 15.4% Water content 24.1% Water content 30.2% Water content 40.4%

0

50

100

150

200

Tim e (m in)

Fig 3.1 b Temperature profil of T2. 35


Effect Of Organic Household Waste Tar Removal By Condensation‌ . Temperature T3 profile 180 160 140

T(oC)

120 100 80

Water content 15.4%

60

Water content 24.1%

40

Water content 30.2% Water content 40.4%

20 0 0

50

100

150

200

Tim e (m in)

Fig 3.1c Temperature profil of T3 Temperature profile T2 and T3 (Figure 3.1b, c) have slightly the same figure with the T1 views that at the higher water content, the temperature drops. But compared to the temperature T1, the difference at each water content getting smaller. This is due to the T1 region, close to the combustion chamber so that the temperature is easy to change due to some of the water that falls down at the start of evaporation.

3.2 Flue Gas Composition The effect of mo isture content of waste on the composition of exhaust gases can be seen in figure 3.2a, b, c. In Figure 3.2 shows that the lower the moisture content the higher the CO composition. At the lowest of 15.4% of mo isture content, which has the highest temperature profile, it is possible a pyrolysis process to occur and produces higher of CO gas, while on the water content of 24.1, 30.2 and 40.4% they are still in the stage of evaporation of volatile materials. Composition of CO 0.14 Wat er cont ent 15.4%

0.12

Wat er cont ent 24.1% Wat er cont ent 30.2% Wat er cont ent 40.4%

CO (%)

0.1 0.08 0.06 0.04 0.02 0 0

50

100

150

200

Tim e (m in)

. Fig. 3.2a Co mposition of CO Composition of CO2 0.8

Water content, 15.4% Water content, 24.1%

0.7

Water content, 30.2% Water content, 40.4%

CO2 (%)

0.6 0.5 0.4 0.3 0.2 0.1 0 0

50

100

150

200

Time (min)

Fig. 3.2 b Co mposition of CO2

36


Effect Of Organic Household Waste Tar Removal By Condensation‌ Composition of Hydrocarbon 80

Water content Water content Water content Water content

70 HC (%)

60

15.4% 24.1% 30.2% 40.4%

50 40 30 20 10 0 0

50

100

150

200

Tim e (m in)

Fig. 3.2c Co mposition of hydrocarbon The correlat ion is quite consistent compared to the results of Yang (2004). The co mposition of CO2 does not much in fluenced by the moisture content in the temperature range studied. This is due to the stage of devolatilizat ion at 360o C ( peak temperature ) whereas the process didn’t influence the CO2 co mposition. The composition of hydrocarbons has reverse effected on the ratio of moisture content. The higher moisture content produces lower HC. The maximu m concentration of HC achieved slower at lo wer moisture content. This is due to the highest moisture content and the devolatilization of volatile matter become slower to reach a maximu m HC concentration. The time to reach maximu m HC content is a function of moisture content and was done at 100, 105, 125, and 145 minutes. 3.3. Effect of Tar removal on Gas Composition The effect of tar condensation on the composition of the exhaust gases can be seen in figure 3.3, 3.4, 3.5, 3.6 a, b, c. In Figure 3.3-3.6 shows the correlat ion of mo isture content and gases compositions of incoming and outgoing gas to condenser. Composition Of CO, water content 15.4% 0.14 Before tar removal

0.12

CO (%)

0.1

After tar removal

0.08 0.06 0.04 0.02

85 10 5 12 5 14 5

65

45

5

25

0

Tim e (m in)

Fig 3.3a Co mposition of CO before and after tar removal, 15,4% moisture content Composition Of CO2, water content 15.4% 0.8 Before tar removal

0.7

CO2 (%)

0.6

After tar removal

0.5 0.4 0.3 0.2 0.1

10 5 12 5 14 5

85

65

45

5

25

0

Tim e (m in)

Fig 3.3 b Co mposition of CO2 before and after tar removal, 15,4% mo isture content 37


Effect Of Organic Household Waste Tar Removal By Condensation‌ Composition Of HC, water content 15.4%

HC(ppm)

80 70

Before tar removal

60

After tar removal

50 40 30 20 10

12 5 14 5

85 10 5

65

45

5

25

0

Tim e (m in)

Fig 3.3c Co mposition of HC befo re and after tar removal, 15,4% moisture content Composition of CO, water content 24.1% 0.12

Before tar removal

0.1

After tar removal

CO (%)

0.08 0.06 0.04 0.02

85 10 5 12 5 14 5

65

45

5

25

0

Tim e (m in)

Fig 3.4a Co mposition of CO before and after tar removal, 24,1% moisture content Composition of CO2, water content 24.1% 0.8

Bef ore tar removal

0.7

Af ter tar removal

CO2(%)

0.6 0.5 0.4 0.3 0.2 0.1

14 5

12 5

10 5

85

65

45

5

25

0

Tim e (m in)

Fig 3.4 b Co mposition of CO2 before and after tar removal, 24.1% mo isture content Composition Of HC, water content 24.1% 80 Bef ore tar removal

70

HC(ppm)

60

Af ter tar removal

50 40 30 20 10

14 5

12 5

10 5

85

65

45

25

5

0

Tim e (m in)

Fig 3.4c Co mposition of HC befo re and after tar removal, 24.1% moisture content

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Effect Of Organic Household Waste Tar Removal By Condensation‌ Composition Of CO, water content 30.2% 0.08 Before tar removal

0.07

CO (%)

0.06

After tar removal

0.05 0.04 0.03 0.02 0.01

85

10 5 12 5 14 5

65

45

5

25

0

Tim e (m in)

Fig 3.5a Co mposition of CO before and after tar removal, 30.2% moisture content Composition Of CO2, water content 30.2% 0.8 Before tar removal

0.7

CO2 (%)

0.6

After tar removal

0.5 0.4 `

0.3 0.2 0.1

14 5

12 5

10 5

85

65

45

5

25

0

Tim e (m in)

Fig 3.5 b Co mposition of CO2 before and after tar removal, 30.2% mo isture content Composition Of HC, water content 30.2% 80 Before tar removal

70

HC(ppm)

60

After tar removal

50 40 30 20 10

12 5 14 5

85 10 5

65

45

5

25

0

Tim e (m in)

Fig 3.5c Co mposition of HC befo re and after tar removal, 30.2% moisture cntent Composition Of CO, water content 40.4% 0.14 Bef ore tar removal

0.12

CO (%)

0.1

Af ter tar removal

0.08 0.06 0.04 0.02

12 5 14 5

85 10 5

65

45

25

5

0

Tim e (m in)

Fig 3.6a Co mposition of CO before and after tar removal, 40.4% moisture content 39


Effect Of Organic Household Waste Tar Removal By Condensation‌ Composition Of CO2, water content 40.4% 0.8 Bef ore tar removal

0.7

CO2 (%)

0.6

Af ter tar removal

0.5 0.4 `

0.3 0.2 0.1

14 5

12 5

85

10 5

65

45

5

25

0

Tim e (m in)

Fig 3.6 b Co mposition of CO2 before and after tar removal, 40.4% mo isture content Composition Of HC, water content 40.4% 70 Bef ore tar removal

60

Af ter tar removal

HC(ppm)

50 40 30 20 10

14 5

12 5

10 5

85

65

45

25

5

0

Tim e (m in)

Fig 3.6c Co mposition of HC befo re and after tar removal, 40.4% moisture content Based on these figure, it can be seen that almost any composition CO, CO2 and HC in the incoming and outgoing condenser, exhaust gas does not change. This is because the CO, CO2 are permanent gas so they can not be removed. Hydrocarbons are a light type compounds, so they could not condensed at the condenser exit temperature at 43o C.During the co mbustion process, some heavy tar condensed in the combustion chamber and stuck to the wall at 153.7 o C. This type of heavy tar will condensed at 200-500o C (Neves, 2011). So me light tar which has a dew point above the condenser temperature will condense and separated from the flue gas in the form of d istillate.In order to evaluate the effect of the separation of tar on the combustion flue gas, condensate was analyzed qualitative ly and quantitatively.. Based on the instrument analysis, resulting the organic compounds in the tar which are hexane, cyclopentane, phenol, p-cresol and guaiacol, and the inorganic compounds are Na, Ca (trace) whereas Cd and ash are negative. In average, a kilogram of waste produced tar mixed with water (pyrolitic water) were 203.3 grams, the tar concentration is 4.297% and ash 0.449% (at the conditions of studied).Based on these data it can be concluded that the separation of tar fro m the flue gas by condensation, could reduce potential pollutants of the above components. This data can be used as a basis for further research in reduction of pollutants quantitatively in more detailed. .

IV. Conclusion In this study, the effect of the removal of organic household waste tar by condensation on the flue gas composition was evaluated. The evaluation focused on the effect of variable moisture content of waste on the composition of CO, CO2 and hydrocarbons in the exhaust gas after tar to be removed. Based on the results and discussion by analysis of the data presented in graphical form, the correlation between the variables studied with exhaust gas temperature, co mposition and analyzing the condensate, it can be concluded as follows: 1) The higher the mo isture content in the waste, the combustion chamber temperature changes more slowly. This affects the rate of evaporation of volatile material o f waste getting slower. 2) The lower moisture content produced higher CO and HC concentrations, while the concentration of CO2 almost constant. 3) Tar separation by condensation will be reduced the concentration of some of heavy types of hydrocarbons, Na metal, and particu late matter in the form o f ash. 4) In general, the co mbustion of dried waste and tar removal can reduce pollutants in the exhaust gases.

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Effect Of Organic Household Waste Tar Removal By Condensation‌ V. Acknowledgements This work was financially supported by Director General o f Higher Educa tion (DIKTI) Min istry of Education And Culture (Kemendikbud)

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