Gas x Air Compressor 1

[Lhenrique]

Hi Fellows,

Is it possible to use an air compressor (370 cfm) to compress natural gas with minor modifications? I means in low presseure mode.

Luiz

 

[Zapster]

No, modifications would not be minor.

 

[Lhenrique]

Zapster,

Could you be more specific?

 

[pmover]

first off, ask the air compressor mfg. you will no doubt get the same answer - NO!

you need to think about the major differences in the gas + materials + operation.

-pmover

 

[crjones]

The manufacturer is the best to answer your question. He will want to know the composition of the natural gas. For instance if it is an oil flooded screw compressor he look for elements that would react with the oil

 

[Zapster]

Think of how the air compressor was designed, and when they went through the design phase, what were the consequents of an air leak?

Now with natural gas, what is the consequence of a natural gas leak?

What would the NEC requirements be for an air compressor?

What would the NEC requirements be for a natural gas compressor?

Answer these questions and you will probably answer your original question that you posted.

 

[Lhenrique]

Thanks for all replies

But I'm sure that with minor modifications it will fit fine for my pourpose.
I'm sure gas compressor vendors would advice me this would not work, 'cause they wanna sell their products, they're right.
What I wanna know is what minor replacement, like sealing, o'rings, explosionproof motors, etc.
The gas I want to compress is 5% ppm of sulfur

 

[Montemayor]

Luiz:

I’ve done the conversion of conventional reciprocating natural compressor to air service while I worked many years ago in Latin America. I’ve also done one 3-stage air reciprocating compressor to natural gas service. I didn’t find that the conversions I did were difficult. Tedious, troublesome, and detailed – but not difficult.

You fail to state what type of compressor you are talking about and all the critical characteristics – like stages, pressures, make, type of drive, lube/non-lube, etc., etc. Why is it that so-called professional engineers that write in queries about compressors to this Forum somehow forget (or don’t know) the differences between a positive displacement machine (recip) and a dynamic machine (centrifugal)? There is a world of difference in their operation and control – some of it involves inherent hazards and important control techniques. Yet, it seems everyone just thinks that a “compressor” just compresses gas and they are all the same. Wrong.

Unless you have a deep and experienced understanding of compressors (both dynamic and positive displacement) you would be wise not to attempt the conversion. Pmover and Zapster are essentially telling you the same advice. This is not a project for a “fast learner”. You either know your S_ _ t or you don’t. And I can only judge what I read in this thread: You haven’t defined the type of machine and you obviously haven’t done it (or seen it done) before. Consequently I wouldn’t attempt it if I were you. What is meant by “low pressure mode”? 350 psig is deemed as “low pressure gas” by me when referring to compressors. Is that what you mean? Also, what do you mean by “5% ppm of sulfur”? Are you referring to H₂S? Or is it SO₂ or SO₃? Sulfur is normally a solid element and is not present in natural gas as such. Without specifics, you can’t generate specific answers.

Specific answers to your queries are:

1) Yes, it is possible to use an air compressor (370 cfm) to compress natural gas with minor modifications.

2) “Replacement, like sealing, o'rings, explosion proof motors, etc.” – including piston rings, piston rod seals, cylinder valves, intercoolers, cylinder liners – are not “minor”. I did my conversions in Latin America for 2 main reasons:

(a) Long delivery on new equipment;
(b) Available used local compressors with minimum hard currency cost.

Unless you have similar imposing conditions and the experienced technical help locally to carry out the conversion, I wouldn’t try it if I were you.

But if you decide to go ahead, good luck and good engineering.

 

[Lhenrique]

Thanks Montemayor

 

[dcasto]

For example a Corken reciprocating gas compressor is a modified Quency air compressor. They add a distance piece so the gas cannot enter the crank case. GasJac takes a Chevy or Ford big block engine and uses one bank as a natural gas compressor and the other bank as a 4 cylinder engine. Screw compressors only need seal materials changed out.

At 5% H2S I'd make sure you have a distance piece in the compressor or verify seal oil in a screw compressor.