Natural Gas Requirement for a gas engine

[asghar]

Gas engine (driver to a compressor) is to be converted from high BTU gas to low BTU gas. Based on available data I have calculated the amount of gas required. Am I on right track? Appreciate your input and comments.

Available Data:

Rated bhp @ 900 rpm = 748 = 558 kWb
Gas Heat Heating Value (existing) = 1040 BTU/ft3
Gas Heat Heating Value (new) = 883 BTU/ft3

Conversion Factor = 42.43 BTU/min per hp (Camron Hydraulic Data book)
Gas Engine efficiency = 35% (assumed)

Calculations:

Ratio of Heating Values = 1040 / 883 = 1.178
Amount of Gas Required = 748 / 0.35 = 2137 hp
= 2137 x 42.43 = 90,679 BTU/min
= 90,679 / 1040 = 87.2 ft3/min
= 125,555 ft3/day

New Gas Requirement = 125,555 x 1.178 = 147,890 ft3/day

 

[quark]

Considering overall efficiency(thermal and mechanical) as 35%, you are right with your calculation. You can straight away consider 90679/883 instead of 90679/1040 and multiplying it with1.178 (hehe... I simplified your calculation)

 

[asghar]

Thanks quark

 

[tickle]

The engine may need to be retuned and the engine management system reprogrammed if a different composition gas is used.

I would check with the engine manufacturer.

 

[asghar]

tickle,
I intend to do that, after finishing my homework. Thanks for the tip.