In gas plants often the compressor oil gets affected by intacting gas ie Chlorine gas which destroys the TAN level very quickly. What are the usual ways of solving this problem if any?

The first thing that comes to mind is to determine how the gas is contaminating the oil. Forgive me if that sounds like a no brainer, but I don't know your equipments process. Refrig compressors combine the oil and refrig and then run through a seperator. Can you provide some insight on your situation?

This is a normal non refrig compressor working in a gas plant. ie compressors air for processes. Appears the compressors intakes cl gas etc which affects the TAN.

Chlorine gas and any hydrocarbon containing oil will chemically react, sometimes violently. You must scrub out the chlorine prior to the compressor. Compressor oil will last only minutes if significant amounts of chlorine are present.

You should do a full safety assesment of your process to make sure you are not creating a situation that could result in injury.

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Originally posted by refrig guy:
Chlorine gas and any hydrocarbon containing oil will chemically react, sometimes violently. You must scrub out the chlorine prior to the compressor. Compressor oil will last only minutes if significant amounts of chlorine are present.

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Refrig Specialist

Does the same phenomenon happen in case compressors if they are situated near pickling plants using HCL commercial acids whereby there could be a possibility of Hcl vapours could be absorbed thro the suction filter?

HCl will affect the oil, but not in the same way as chlorine gas. HCl can promote oil sludging, especially in the presence of moisture and heat. The HCl has a catalytic effect on the oil allowing it to react with itself to form high viscosity polymers (sludge).

Chlorine gas acts as a strong oxidizer and will react chemically with the oil, the same as oxygen will.

Thanks Refrig Guy for that piece of information.

We had problems with rotary compressor oil situated in Industries with pickling facilities.

Are there any solutions?

Thanks once again

I have a couple of thoughts. You may want to put acid scavenging filters on the vents to the compressor. A filter containing alumina or other alkaline material should scrub out the HCl in the air prior to getting into the oil. Make sure you prevent any particulates in the scrubber from getting into the compressor. You could use some sort of color change indicator based on pH to determine when the filter becomes exhausted.

The other way to protect the oil is to prevent the formation of metal chlorides, especially ferric chloride, in the oil that are the catalysts for oil breakdown. Alkaline detergency additives should help, but will become exhausted over time.

Besides installing filter or absorber to scrub the chemical gas, some synthetic oils like polyglycol, polyether or silicone etc. will have better performance than PAO and mineral oils'.

There is a compressor oil purification product by Fluid Metrics LLC that is ideally suited for controlling acidic and oxidizing gas contamination of rotary screw compressor fluids. This product, which also works great at extending oil service life of non-contaminated compressor oils, uses ion exchange technology to remove acids from the oil. Go to fluidmetrics.com to download brochure.