20 Generation of formaldehyde during vacuum extraction has been used in the storage of resin-
4.2 Production of Activated Carbon
4.2.1 Activated Carbon produced in Type A Furnace
The following are the general steps applied in producing Activated Carbon in Type A Furnace
First the small pot was filled with raw material. The capacity of the pot was around 0.250 kg.
Then the top of the pot was closed and sealed with clay.
Next the pot was placed in the furnace.
ci) Then the cover of the furnace was closed and also sealed with clay.
e) The fuel was placed on the grit and burning started. When the process was going on the smoke produced in the furnace entered the pot through the bottom opening and passed -r
out through the top opening which was connected with smoke outlet. This heated air and the produced heat were used for producing activated carbon.
A digital thermometer was placed inside the pot to record the inside temperature. The furnace was fueled until the furnace temperature reached above 500 °C and maintained the furnace temperature above 500 °C for about 2 hours.
The smoke came out from the furnace and was also observed. Initially the smoke color was black.
When the smoke color turned into white, all the openings were sealed with clay. The outlet temperature was observed as 82 °C when white smoke came out.
Then the sealed furnace was kept for 24 hours and opened to bring out the produced activated carbon.
Batch lofTvne A Furnace
This batch was conducted on September 07, 2009.250gm rice husk was collected in a 10.16cm diameter small pot. The rice husk was in compacted condition in the pot. Then the pot was closed, sealed and put in the furnace. Then the cover of the furnace was closed and also sealed with clay. A digital thermometer was placed inside the pot from the top cover of the furnace to measure the temperature. Then the fuel was placed on the grit and started burning. When the Process was going on, the smoke produced in the furnace entered the pot through the bottom opening and passes out through the top opening which was connected with smoke outlet. This heated air and the produced heat was used for producing activated carbon. The furnace was fueled until the ulirnace temperature reached above 400 °C and maimainccl the furnace temperature above 400 °C for 1.5 hours. The highest temperature was recorded 474 T. The smoke can-ic out from the furnace was also observed. Initially the smoke color was black. When the smoke color turned into white, all the openings including the smoke outlet were sealed with clay. Then the sealed furnace was kept for 24 hours and after that it was opened to bring out the produced activated carbon. Continuous monitoring of sealing was provided because clay layer was cracked after some hours by propagation of heat.
Result
Only 78.5 gm activated carbon was found from this batch experiment which is 3 1.4% of the raw material of 250 gm. The rice husk was finely burnt and produced good quality activated carbon.
As fuel of 5.3 kg firewood and 100 rnL of oil were used. The temperature variation is shown in Figure 4.1. The production cost is found to be 478 BDT per kg. Detailed cost analysis is shown in Appendix A.
1*1 450 400
350 300 250 200 150 100 50 0
0 2 4 6 8 10
Time in hours
Figure 4. 1: Temperature variation with time at the production stage
Batch 2 of Type A Furnace
This batch was conducted on October 19, 2009. 210 gin rice husk was collected in a 10.16 cm diameter small pot. The rice husk was in compacted condition in the pot. Then the pot was closed and put in the furnace. Then the cover of the furnace was closed and also sealed with clay.
A digital thermometer was placed inside the pot from the top cover of the furnace to measure the temperature. Then the fuel was placed on the grit and started burning. When the Process was going on, the smoke produced in the furnace entered the pot through the bottom opening and passed out through the top opening which was connected with smoke outlet. This heated air and the produced heat was used for producing activated carbon. The furnace was fueled until the furnace temperature reached above 400 °C and maintained the furnace temperature above 400 °C
for 3 hours. The highest temperature was recorded 553 °C. The smoke came out from the furnace was also observed. Initially the smoke color was black. When the smoke color turned into white, all the openings were sealed with clay. Then the sealed furnace was kept for 24 hours and opened to bring out the produced activated carbon. Continuous monitoring of sealing was provided because clay layer was cracked after some hours by propagation of heat.
Result
Only 82.46 gm activated carbon was produced from this batch experiment which is 39.27% of the raw material 2 10 gm. The rice husk was finely burnt and produced good quality activated carbon. As fuel of 6 kg firewood and 100 mL of oil were used. The temperature variation was shown in Figure 4.5. The production cost is found to be 503 BDT per kg. Detailed cost analysis is shown in Appendix A.
6C
SC
C) 4
1 301 C.)
20(
0 2 4 6 6 10
Time in hours
Figure 4.2: Temperature variation with time at the production stage
70 Batch 3 of Type A Furnace
This batch was conducted on October 20, 2009. In this batch the 240 gm rice husk was mixed with an aqueous solution of ammonium sulphate (activating chemical) made by dissolving 50 g of ammonium sulphate in 300 mL of distilled water. Then the soaked rice husk was put in a 10. 16 cm diameter small pot. The rice husk was in compacted condition in the pot. Then the pot was closed, sealed and put in the furnace. Then the cover of the furnace was closed and also sealed with clay. A digital thermometer was placed inside the pot from the top cover of the furnace to measure the temperature. Then the fuel was placed on the grit and burning started.
When the process was going on the smoke produced in the furnace entered the pot through the bottom opening and passes out through the top opening which was connected with smoke outlet.
This heated air and the produced heat was used for producing activated carbon. The furnace was fueled until the furnace temperature reached above 400 °C and maintained the furnace temperature above 400 °C for 3 hours. The highest temperature was recorded 534 °C. The smoke came out from the furnace and was also observed. Initially the smoke color was black. When the smoke color turned into white, all the openings were sealed with clay. Then the sealed furnace was kept for 24 hours and opened to bring out the produced activated carbon. Continuous monitoring of sealing was provided because clay layer was cracked after some hours by propagation of heat.
Result
Only 128 gm activated carbon was found from this batch experiment which is 53.33% of the raw material of 240 gm. The activated carbon finely burnt. As fuel of 6 kg firewood and 100 mL of oil were used. The temperature variation was shown in Figure 4.6. The production cost is found to be 536 BDT per kg. Detailed cost analysis is shown in Appendix A.
.1•
500
L) 0
400
300
E 200
OM
0'
qr 0 2 4
6 8 10
Time in hours
Figure 4.3: Temperature variation with time at the production stage
600
500
400
300
200
Batch 1 100 ---Batch 2 Batch 3
0 2 4 6 8 10
Time in hours
Figure 4.4: Temperature variation with time at the production stage in Type A furnace for different batches
12
72
It was seen from Figure 4.4 that, the temperature above 400 °C was maintained for about 2.5 hours for every batch test which is favorable condition for production of activated carbon.