3 replies to this topic

[iceman53y]

I am intending to buy a catalytic converter for an engine exhaust.
Catalytic converter manufacturers require the amount of SO₂ at the exhaust in PPM.
Can someone please tell me how to calculate the PPM of SO₂ from the following data?

Engine Power = 1980 bhp
BSFC = 7792 Btu/bhp-hr
Total exhaust heat = 4527 Btu/hr
Exhaust flow = 13713 lb/hr
H2S content of the inlet Natural gas is 800 PPM.
I need the amount of SO₂ in PPM at the exhaust.
Assume worst case scenario that all the H₂S gets converted to SO_2.

Please let me know if any further information is required for this calculation.

Thanks.

[iceman53y]

Total exhaust heat = 4527 Btu/hr x 1000 = 4527000 BTU/hr

[ankur2061]

iceman,

I am assuming that the ppm value you have provided is by volume and not by weight since you do not mention the basis (volume or weight). General practice is to specify the composition of exhaust or flue gases in volume or molar terms.

Now you have 800 ppmv of H2S in your natural gas. In molar terms, 1*E6 moles of natural gas contains 800 moles of H2S. The combustion reaction of H2S in your catalytic converter can be represented by the stoichiometric reaction as follows:

2H2S + 3O2 = 2SO2 + 2H2O

From the above reaction, it is clear that for 2 moles of SO2 to form from sulfur present in the H2S you require 2 moles of H2S and 3 moles of O2 based on 100% theoretical conversion of the H2S present in the natural gas.

From the above it is clear that 800 moles of H2S will give 800 moles of SO2 at the outlet of the converter considering complete combustion. So the SO2 ppm in your exhaust is 800 ppmv.

Regards,
Ankur

[iceman53y]

Yes 800ppm is mole % by volume of H2S in the gas inlet of the engine.