Biogas flow? Temperature? Pressure? Heating Value? Steam Generation? Finally can get Power Output
No time to get into calculation, as busy. For reference and understanding power generation from IC engine
High quality biogas is produced from anaerobic digesting facilities where the waste stream is pre-treated and the parameters that lead to biogas production are being monitored and controlled.
Biogas can be used as a heat source to power thermal engines to produce mechanical work which by terns can be used to power pumps, blowers and other machines in site or to power electric generators to produce electricity. Approximately 75 % of the LFG recovery facilities in the U.S. generate electricity • Internal combustion (IC) engines used to generate electricity are most commonly "lean burn" turbocharged designs that burn fuel with excess air. Less commonly, IC engines may be "naturally aspirated" without turbo charging. The naturally aspirated engines are easier to operate because they are less complex, but they have reduced power output and higher emissions. When operated on biogas, engine power ratings are commonly reduced by 5 to 15 % compared to operation on natural gas. The overall heat rate ranges from 2.700 to 3.500 kcal of biogas per kilowatt hour (kwh). IC engines drive generators to produce electrical power that is typically sold to the local electric utility. Four manufacturers (Caterpillar, Waukesha, Cooper-Superior, and Cummings) are the primary suppliers of these engineers. The IC engines have been specially designed for biogas applications. There are two main types of gas reciprocating engine: ● dual-fuel (compression ignition) engines (otto cycle) ● Spark ignition engines.(diesel cycle)
Ref:SCS Engineers, Implemetation guide for landfill gas recovery projects in the northeast. September 1994
"A cubic foot of natural gas gives off 1000 Btu, but the range of values is 500 to 1500 Btu." [Std. 37 MJ (average) & 19–56 MJ (range)] Ref: naturalgas.com
"The net heating value of natural gas served by a utility company is often 1000 to 1100 Btu/ft3." [Std. 37–41 MJ] Ref: "Fuel Gas." McGraw Hill Encyclopedia of Science & Technology. McGraw Hill, Inc., 1982.
Calorific value of pure Methane is 14,600 kcal/kg which is equivalent to 5600 kcal/m3. For calculating the power output from this gas, divide by 860. 860 kcal = 1 kw. So, for 1 m3 methane gas theoritically you can generate 6.5 kw. However, when you convert this cal vale to electric energy, there is a loss of efficiency in the conversion process. Typically IC engines run on gas will have 30 to 35% efficiency. So, when you convert 6.5 kw with 30% efficiency, you will get 1.95 to 2 kw. This is how you can calculate the power generation from any fuel source if you know the calorific value.
Let me be Very Clear: if methane is generated from UASB you can assume 55% Methane in the Gas:The density of the gas would be 0.82. The Total Energy(kcal) value would be 4800kcal. The potential Power would be /861/24. and the actual power conisdering generator with 38% Efficiency (Highest currently available)
e.g. 1m3 of Gas:
1 x 0.82 then x 4800 then /861 /24 and then again x .38 would give you your available power in KWH.
Yes.. We have done few power projects using methane into gas engines. The purity of methane decides the no. of units. In LPG/CNG methane % much higher. In that event, the gas engine can generate upto 3-4 units of electricity per cubmic meter. Whileas, methane being 65% in biogas, gas engine can generate upto 2 units. Please feel free to call me 09822394170 for any further clarification. Regards
If Methane is generated from UASB process, this biogas would contain methane & CO2, if you want to generate power you would have to increase methane concentration by either
1. Using amines column to absorb CO2 or
2. Using membranes to separate methane from CO2
Calorific value of methane on 100% basis is around 5600 Kcal/Nm3, check from textbooks
Replies
Please find a sheet attached for reference to calculate the heating value. Hope this will help.
Cheers
Heating_Value_of_Biogas.pdf
Temperature?
Pressure?
Heating Value?
Steam Generation?
Finally can get Power Output
No time to get into calculation, as busy. For reference and understanding power generation from IC engine
High quality biogas is produced from anaerobic digesting facilities where the waste stream is pre-treated and the parameters that lead to biogas production are being monitored and controlled.
Biogas can be used as a heat source to power thermal engines to produce mechanical work which by terns can be used to power pumps, blowers and other machines in site or to power electric generators to produce electricity. Approximately 75 % of the LFG recovery facilities in the U.S. generate electricity
• Internal combustion (IC) engines used to generate electricity are most commonly "lean burn" turbocharged
designs that burn fuel with excess air. Less commonly, IC engines may be "naturally aspirated" without turbo
charging. The naturally aspirated engines are easier to operate because they are less complex, but they have
reduced power output and higher emissions.
When operated on biogas, engine power ratings are commonly reduced by 5 to 15 % compared to operation on
natural gas. The overall heat rate ranges from 2.700 to 3.500 kcal of biogas per kilowatt hour (kwh). IC engines
drive generators to produce electrical power that is typically sold to the local electric utility. Four manufacturers
(Caterpillar, Waukesha, Cooper-Superior, and Cummings) are the primary suppliers of these engineers. The IC
engines have been specially designed for biogas applications. There are two main types of gas reciprocating engine:
● dual-fuel (compression ignition) engines (otto cycle)
● Spark ignition engines.(diesel cycle)
Ref:SCS Engineers, Implemetation guide for landfill gas recovery projects in the northeast. September 1994
"A cubic foot of natural gas gives off 1000 Btu, but the range of values is 500 to 1500 Btu." [Std. 37 MJ (average) & 19–56 MJ (range)] Ref: naturalgas.com
"The net heating value of natural gas served by a utility company is often 1000 to 1100 Btu/ft3." [Std. 37–41 MJ] Ref: "Fuel Gas." McGraw Hill Encyclopedia of Science & Technology. McGraw Hill, Inc., 1982.
Let me be Very Clear: if methane is generated from UASB you can assume 55% Methane in the Gas:The density of the gas would be 0.82. The Total Energy(kcal) value would be 4800kcal. The potential Power would be /861/24. and the actual power conisdering generator with 38% Efficiency (Highest currently available)
e.g. 1m3 of Gas:
1 x 0.82 then x 4800 then /861 /24 and then again x .38 would give you your available power in KWH.
Hope it would be now very clear.
If Methane is generated from UASB process, this biogas would contain methane & CO2, if you want to generate power you would have to increase methane concentration by either
1. Using amines column to absorb CO2 or
2. Using membranes to separate methane from CO2
Calorific value of methane on 100% basis is around 5600 Kcal/Nm3, check from textbooks
Ramesh Ukidve
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