FYP update no.22
Thursday, October 22, 2009

COMMISSIONING OF ACTUAL DIGESTER SYSTEM (AEROBIC)

After allowing 10 days for anaerobic digestion, we commenced with the transfer of the sludge to the 2nd stage of the digestion process known as the Aerobic digestion stage. The Aerobic stage consists of maintaining the temperature at an optimum of 60 degrees celsius for the aerobic bacteria also known as thermophilic bacteria. It will also consist of aeration for bacterial activity. The procedure for commissioning of the aerobic stage is as follows: (refer to diagram below for line tracing)
1. We collected the sample for the anaerobic stage before the transferrence of sludge.
2.We proceeded to transfer the sludge to the 2nd stage by opening V3. Transfer is complete when we can no longer hear any sound of the sludge running through the digester. At this point, the sludge is mostly liquid, hence it can easily be transferred. In addition, a loud rushing sound can be heard during the transfer.
3. We proceeded to line up the Heat Exchanger H1 to E-1, opening V7, 8, 9, 10 and 11 while closing V-18 and V-6. We crack open V5 in preparation to fill the Heat Exchanger with water and circulate.
4. We switched on the main power supply for the E-1 as well as the main water supply.
5. We adjusted V5 to control the flowrate of the water entering the exchanger. Coordination is required.
6. We waited for awhile to check whether the heating element is working by feeling for any heat around the heat exchanger.
7. After the compressed air, A-1 has been properly lined up to the digester system, we proceeded to turn on PR-1 and adjust to control the air flowrate. The pressure was controlled manually and measured using PG-1. Bubbling was heard. After approximately 10 minutes, we stop the aeration and lock off the compresed air valve. Aeration is done almost daily for 10 minutes approx.
8. allow aerobic process to run for 10 days.
9. Collect Aerobic sample.


Fig 1: Labeled Diagram of Digester


Fig 2: Opening V3 for transfer of sludge.


Fig 3: Close up of V3


Fig 4: Lining up of Heat Exchanger


Fig 5: Collection of sample via sampling valve.


Fig 6: Connection of main water supply


Fig 7: Main water supply hose was connected to overflow pipe which is undesired. Efforts were made to dislodge the two pipes and reconnect the main water supply hose to the Heat Exchanger inlet hose.


Fig 8: Connection of compressed air tank to the digester. Care has to be taken when moving the air tank. Collapse of the tank can cause an explosion which is undesired and dangerous.


Fig 9: Close up view of PG-1 and PG-2 of the compressed air tank as well as the regulator

The commissioning was a success and we proceeded to wait 10 days for the completion of the process.

Posted byfishy* ><>
at10:40 AM

0 comments
 

0 comments:

Post a Comment

Subscribe to: Post Comments (Atom)