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Sail_Tech
10-19-2008, 09:03 PM
Hello,

Can anyone help me convert N.m3/min to kg/h for exhaust gas flow from a CAT natural gas engine?

Here's what I've got:
N.m3/min: 11
Temp: 488 degreees C

What else do I need to provide?
Inlet air flow: 10 N.m3/min
Fuel consupmtion: 50 N.m3/hr

Thanks,
Delian.

JohnS
10-20-2008, 05:12 AM
Hello,

Can anyone help me convert N.m3/min to kg/h for exhaust gas flow from a CAT natural gas engine?

Here's what I've got:
N.m3/min: 11
Temp: 488 degreees C

What else do I need to provide?
Inlet air flow: 10 N.m3/min
Fuel consupmtion: 50 N.m3/hr

Thanks,
Delian.

I think the easiest approach is the conservation of mass. The exhaust mass flow must equal the sum of air and fuel inlow. If you want any great precision, you need an average molecular weight for your natural gas. Pure methane is 16 g/mol, but natural gas contains percentages of other gases and is usually in the range 16-20. I will use 18. The average molecular weight for air is 29 g/mol.

Air consumption: 10 Nm³/min = 600 Nm³/h
For ideal gas 22.414 m³/kmol, so 26.77 kmol/h, molar mass of air may also be expressed as 29 kg/kmol, hence 776.3 kg/h.

Fuel flow: 50 Nm³/h x 1 kmol/22.414 m³ x 18 kg/kmol = 40.15 kg/h.

Exhaust flow is the sum, 816.5 kg/h. If you have a better MW for your natural gas, redo the gas calculation, following this as a template.