Compressor Wash Fluids

[TPL]

I have a couple of centrifugal gas compressor units which have gone out of balance at the same time - this has coincided with problems with a system that injected wax inhibitor into the gas stream, so it looks as if waxy deposits on the rotors are responsible.

I have tried a wash to eliminate salt deposits (with the compressor at rest, injecting water into the bottom of the barrel and turning the rotor by hand through several 90 degree intervals) without improving the situation, so I now want to try a wash using a hydrocarbon solvent.

I have 3 constraints:

a) The wash fluid should not be dangerous to personnel - e.g. no benzene
b)There is a slight chance that the wash fluid will enter the dry gas seals, so the solvent must not dissolve viton O-rings
c)Since these units are located offshore there are environmental requirements - just in case any of the wash fluid escapes into the sea, it must be reasonably doplhin friendly

I have contacted several major chemical suppliers, but the quanitities that I am looking for (intially 200 litres) haven't don't seem to generate much interest.

Anyone able to recommend a wash fluid that might help?

thanks

 

[zdas04]

You've got me a little confused. Do you believe the problem is wax or salt? If it is wax build up then I've had good luck with soaking the process with plain old kerosene.

Salt (phase change scale) is a very different problem. NaCl salts can be disolved with hot water. Nahcolite salts are another kettle of fish that don't disolve in water and require strong acids that could be detrimental to your seals.

David

 

[TPL]

Thanks for the reply - sorry for the confusion - the problem is that we really don't know what the cause of the problem is, so we try the easiest thing first i.e. water wash just in case it is a salt deposit problem.

Our inhouse chemists doubt that diesel or kerosene would work.

It might not even be wax, but a bit of detective work (after the water wash) did show that the wax inhibit system wasn't fully functional, so this is our next line of attack. In our geographic location, any discharge into the sea has to be reported and there are penalties for 'killing dolphins', so I am looking for an environmentally friendly solvent.

There are some operators further north who suffer from iron carbonate fouling and wash their compressors with acetic acid.

This problem involves 2 compressor trains that were commissioned early in 2006 - each train has a separate LP and HP barrel - both trains started showing an ongoing increase in 1X vibration (discharge end in LP barrel and both ends in the HP Barrel) in February and B train is just about inoperable due to high vibration.

Without dismantling the compressors (a big, big job), I cannot find a way in to see what the problem is, so I 'll try a couple of different wash fluids and if thats unsuccessful, I will gear up for field balancing to buy a bit more time to figure out the root cause.

 

[sms]

Call Nalco, they have several washes that they can design depending on the process.

-The future's so bright I gotta wear shades! B-)

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[zdas04]

I've addressed parrafin problems with both deisel and kerosene. The kerosene was at least an order of magnitude better (i.e., 1/10 as much liquid to disolve the same amount of wax) than deisel (my chemists said that deisel is very waxy itself). I was working in CBM and had a test done with kerosene, P38, and deisel to see which left the most residue behind and which disolved the most parrafin. The kerosene was best, P38 not much worse, and the deisel was worthless.

Without knowing the water chemistry it is hard to say what might disolve a salt. Very hot water (near boiling) is really effective on a bunch of simple salts. If they're more complex then I'd try a mild acid (again, heat seems to help).

David

 

[sms]

We use boiler feed water for ammonia salts. What is the process? Sounds like a refinery compressor..

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