experience in closed anaerobic digesters operation for pome biogas harnessing under cdm project by...
TRANSCRIPT
Experience in Closed Anaerobic Digesters Operation
for POME Biogas Harnessing Under CDM Project
By
Ir. RM Subbiah and Tuan Haji Alui Ahmad
Green & Smart Sdn. Bhd.www.greens.com.my
Anaerobic Technology (no air required for microbial survival)
Traditionally used A.D. types in
POME treatment• Deep open tanks• Deep lagoons
(Biogas released to atmosphere, GHG)
OPEN TANKOPEN TANK
GHG contribute to global warming
POME Biogas contains 45% to 80% methane, which has 21 times higher global warming potential than CO2
New AD types used for
POME treatment based on
“Clean Development Mechanism” (CDM) principles
• Closed lagoon with covering• Closed tanks with stirring
(Biogas harnessed)
CLOSED LAGOONCLOSED LAGOON
Completely Stirred Tank (CST)System
Stir the tank content by:
•Using biogas itself•Using stirrers•Using pumps
POME – MAS TM
Palm Oil Mill Effluent – Mesophilic Anaerobic System
Temperature range 320C – 400C
POME-MASTM System
System used in 4 Palm Oil MillsTotal digesters : 12
Sizes:1700m3, 2200m3, 3600m3, 5800m3
ResultsResults COD Reduction Efficiency COD Reduction Efficiency
All Digesters Design Mill 1 Mill 2
COD Inlet
(mg/L)55000
Range
42700 – 65940
Mean
55349
Range
26500 - 151700
Mean
54577
COD Outlet (mg/L)
5000
Range
2585 – 4537
Mean
3721
Range
2832 – 7690
Mean
4421COD
Reduction90% 93.22% 90.10%
Feed Quantity m3/day 120 288
Graph Showing Typical Results On Daily BasisGraph Showing Typical Results On Daily BasisFigure 1: 1700 m3 Anaerobic Digester Monitoring Results
Figure 2: 3600 m3 Anaerobic Digester Monitoring Results
Reactors are running sustainably for more than 12 months
Longest running > 24 months
Biogas production depends on• Effluent flow rate• Incoming COD value• Effluent temperature
Typical ValuesTypical Values
Mill production: 40T FFB/HrPOME: 24m3/Hr
Incoming COD total: 55,000 mg/lCOD reduction efficiency in the digester: 92%
Methane production: 425m3/hrBiogas at 60% CH4 content: 708m3/Hr
Theoretical power generation potential: 1274kW-1558kW
COD reduction values measured in POME-MASTM
varies from 90% to 95%
CH4 (Methane) values measured in POME-MASTM
varies from 60% to 75%
BIOGAS PRODUCTION AT DIFFERENT COD REDUCTION EFFICIENCIES & DIFFERENT METHANE CONTENT
Mill capacity FFB m3/hr 40
Effluent Flow rate m3/hr 24
Inlet COD Mg/l 55 000
COD reduction efficiency see table
Assumption : Running on full load on above capacity1 kg COD reduction gives 0.35m3 Methane
Biogas Production at different methane
concentration
Biogas Production at different COD reduction % (m3/hr)
75% 80% 85% 90% 95%
At 55 % 630 672 714 756 798
At 60 % 578 616 655 693 732
At 65 % 533 569 604 640 675At 70 % 495 528 561 594 627
ESTIMATED ELECTRICITY PRODUCTION
Electricity Production
COD reduction efficiency 75% 80% 85% 90% 95%
Biogas Production at 60% methane concentration 578 616 655 693 732
Potential electrical power at 2kW* hr/m3 of biogas
(kWh)1156 1232 1310 1386 1464
* Can vary from 1.8kW to 2.3kW per m3 of biogas based on generator efficiency
Efficiency Difference - Commercial Value
Every 5% difference in gas production means extra 500,000 kWh/year
@ RM 0.30/kWh = RM 150,000For 21 years SREP feed in tariff difference in
revenue = RM 3.15million
Flare
CDM compliant GREEN-FLARETM
Exhaust temperature set 6100C maintained at 610 + 30C
Gas retention time about 0.86 seconds
Conclusion
• POME-MASTM system gives high COD reduction efficiency > 90%• Takes shock loads
• CH4 contents 60% to 75% in Biogas
• Runs in sustainable manner either on continuous or batch feed mode • GREEN-FLARETM (CDM compliant closed flare)
maintains same set exhaust temperature for different gas flows
Thank You
Presenter:Ir. RM.Subbiah (012-2181903)
Green & Smart Sdn. Bhd.www.greens.com.my