Fuel Composition 1

[sethkett]

What are tolerable levels of Hydrogen Sulfide in Fuel? I am planning to run a natural gas automotive engine on BioGas.
To do so, I will be making a scrubbing system to remove H2S and CO2 from BioGas, but I need to know how much H2S an engine will tolerate. Any help, any references would be most helpful!

 

[ivymike]

The answer likely depends on your selection of aftertreatment devices...

 

[swall]

Outside of the deleterious effects of sulfur dioxide combustion products on valves and exhaust systems,why remove the hydrogen sulfide? It does have some btu content, about 2/3 that of methane if I recall.

 

[franzh]

I attended a conference last week about fuel systems. One of the primary areas of discussion was removing the sulfuur products from fuels. Fuel Cells cannot tolerate it, current catalysts are poisoned by it. An engine would not significantly notice the presence (or absence) of sulfur, within reasonable levels.
One note that surfaced, exhaust catalysts showed some significant amount of regeneration when the sulfur levels were removed (from 160ppm to 40 ppm). Also of worthy comment, this was using gaseous fuels.
Franz

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[patprimmer]

If the H2S gets through the engine, or escapes from the tank, it has a detrimental effect on people, as well as on engines.

If it does burn, it produces quite strongly acid byproducts. I would think you want very low concentrations, but I have no idea for actual numbers.

Franz's data suggests less than 160 ppm as sulphur as the max., but 40 ppm as quite acceptable.

Regards
pat pprimmer@acay.com.au
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[franzh]

With new fuel standards demanding ever decreasing amounts of sulfur, even 40 ppm is too high. In the test I viewed, LPG motorfuel was doped with 160 ppm sulfur in a worst-case scenario, and catalyst degredation was studied. When it was returned to 40 ppm, it (the catalyst) regenerated. Personally, I expect to see almost all sulfur removed from fuel in the very near future, (as far as technically possible, considering the current state of fuel storage and transportation).

Thanks, Pat, for pointing that out.
Franz

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[swall]

I was thinking along the lines of this being an automotive engine used in a stationary application, such as a generator, where no emissions controls would be in use.Question came up once before with hog farms in North Carolina, where there was an interest in using the biofuel right from the manure pit to power a atatinary engine for power generation.

 

[btrueblood]

The H2S is already naturally coming off the manure pit due to natural fermentation (or whatever), right? All you will be doing is hastening its oxidation by burning it. I would strongly doubt that the EPA would have issues with the application (rural auxilliary power generation), much less jurisdiction. Burn it!

 

[crysta1c1ear]

Aparently minimum amounts of H2S in natural gas are determined by odour detection: you want to be able to know when there is a leak. Maximum permitted sulpher seem to be determined by the fact that natural gas is sometimes used for flueless indoor heating.

So since your question was about what level can the engine tolerate, the legal limits on 'natural gas' are irrelevant.

The engine won't know whether it is being used in a car or a hog-farm power generator. So the comments in here will still apply....

International Association for Natural Gas vehicles.

http://www.iangv.org/jaytech/files/IANGVGasCompositionStudyDecember2002.pdf

Effects of Natural Gas composition variations on the operation, performance and exhaust emissions of natural gas powered vehicles.

 

[GregLocock]

The diesel in Australia has too much sulphur for modern high performance automotive diesel engines. I don't know what the specific issue is, it could just be poisoning the cats.



Cheers

Greg Locock