Oil in the main cooling zone?
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I would like to ask the experienced colleagues: during the initial phase of liquid accumulation when we opened the drain valves for the main cooler and the liquid air separator, we noticed black liquid beneath those valves. Additionally, the resistance in the plate heat exchanger increased, which led to the shutdown of the system. Could it be that there is oil in the air? If it’s not oily, then what’s the reason? How to handle it?
Black liquid? When sampling using a container, it should be yellow small particles; if any are missing, check the booster pump, expander, oil seals and gears, as well as the pressure of the sealing gas, etc
The possibility of oil being present is low; an analysis will confirm this. If oil does get into the system, it doesn’t seem like there’s a very good solution. I recommend sealing off each pipeline and equipment component using blind flanges and then purging them until the oil analysis shows no contamination
Carbon tetrachloride is degreased, so it can be tried; there is usually no oil in the air. Check the expander – you can open the volute drain to inspect it.
First, conduct an oil analysis; if it is oil, it’s best to check the expander first to see whether the seal gas and other elements are functioning properly. It is best, as mentioned above, to purge each section separately.
If it’s oil, it can be a bit dangerous. It could also be other impurities.
Perform an analysis on the main cooler to check whether oil from the expander has entered the system. If oil does get in, there isn’t much that can be done about it; even cleaning may not allow all areas to be cleaned thoroughly. I hope you don’t get oil in it.
The difference between oil and water isn’t that difficult, right? If it is water, a regeneration drying device ； If it is oil-based or contains oil, use a degreasing solution to circulate and clean all parts until analysis shows no oil remains.