What amount of oil injection in a reciprocating compressor can cause liquid slugging?
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I’d like to discuss with everyone: what should be the appropriate amount of packing for reciprocating compressors and the oil volume to be injected into the cylinders? What are the standards that govern this? Why was this question raised? A few days ago, our company resumed operations, and the part of the piston rod of the cyclic hydrogen compressor that is inside the piston broke. And it was two units, one after the other, with less than 20 minutes between them. While investigating the cause, the manufacturer suggested that it was due to an excessive amount of oil injection. Our oil injection rate at that time was 4 to 5 seconds per drop, so liquid slugging should not have occurred. The point where the piston rod broke is exactly at the junction of the hollow structure and the solid rod. I would like to ask the experts: what exactly causes the piston rod to break?
We require no more than 10 drops per minute
We require 2-3 drops per minute
We use low-oil lubrication for compressors that operate with contaminated oil. I hope everyone can provide useful suggestions; the key is to identify the standards and how to implement them
The compressors and circulators used for low-pressure methanol in our plant operate at a rate of 2–10 drops per minute; higher rates can lead to carbon buildup, and we have not experienced any liquid slugging yet
If it is a newly installed compressor, it could also be due to installation issues, such as insufficient clearance
There are 5 pivot gaps; it’s not that the reason.
There are many reasons for piston rod failure: the piston force may exceed the bearing capacity of the piston rod, or there may be issues with the quality of the piston rod itself, as well as problems related to its design, material selection, or manufacturing process. There are various causes for excessive piston force, and each case needs to be analyzed on a case-by-case basis. I don’t think simply adding a bit more oil could cause such a big impact. The manufacturer is shirking responsibility
Isn’t there anything more professional?
I was asked this question before by a friend of mine. The amount of oil injected into the compressor is related to factors such as the cylinder diameter under which the compressor operates; it varies from one manufacturer to another, with no universal value. As you mentioned, around 12 drops per minute seems to be the amount in your case, and this is quite normal for a hydrogen circulation machine. I’m not sure what the recommended amount is according to the manufacturer There are many reasons for the breakage of compressor piston rods; if a large amount of liquid is present in the circulating hydrogen, that could be the cause. If not, it’s likely the manufacturer is trying to shirk responsibility – the amount of oil applied is not sufficient to handle such liquid content. Generally, such issues are related to the calculation of loads on the materials and piston rods, especially the calculation of the piston thrust and the reverse angle in reciprocating machines.