Air compressor seal
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In addition to comb seal types, what other sealing methods are used for air compressors? Is air generally used for sealing? Won’t that cause the oil in the bearing housing to oxidize? Isn’t it better to use nitrogen? Also, why do centrifugal pumps necessarily require air sealing instead of simple packing seals? Is dry gas sealing more effective? Please, experts, discuss this and help me out
In my understanding, in the lubrication system of an air compressor, the oil pressure should be higher than the pressure of the seal, so that air cannot get into the oil.
Reply to 2# asdfqcf: Can the seal still function then? Even with a labyrinth seal oil, it’s possible for fluid to leak into the main machine, so a seal is necessary. On the units I used to operate, dry gas seals from Johnson Controls were used to prevent gas leakage inside the main machine; there was no need for an air compressor, just a seal oil system was sufficient
Reply to 3# lizhenpeng: The gas compressed by our air compressor is atmospheric air that has been initially filtered. The pressure of the sealed gas, after passing through two pressure regulators, is 3 kPa; the pressure at the inlet of the bearing lubricating oil is 0.18 MPa. The internal oil pressure must be at least 3 kPa, so I believe that the sealed gas will not enter the oil. Another point is that when the sealing gas leaks, it is released into the atmosphere; it should not cause any compression medium to leak in. This is just my personal opinion, so please correct me if I’m wrong
Reply to 4# asdfqcf: Perhaps I misunderstood something. In my previous experiences, the pressure level of the nitrogen used for sealing was 8 bar; after pressure reduction, it should still be 4 bar. Therefore, part of the nitrogen had to return to the tank along with the oil, while the other part was discharged through the pipes above the bearing box. The pressure of this air needed to be much lower. Since I have never operated a air compressor, I didn’t quite understand this simple sealing process. Now I basically get it. Thank you
Reply to 5# lizhenpeng: It was also my own understanding, but your confirmation proves that I was right. Let’s learn together; you’re welcome
There are also some centrifugal pumps for which an air seal is necessary instead of a simple packing seal; is a dry gas seal more effective? No one has yet commented on this issue
1. The pressure of the sealing air in the air compressor is higher than the oil pressure, so oil does not enter the gas; there is also an exhaust line for excess air on the bearing housing. 2. The lubricating oil for centrifugal compressors is all antioxidant. 3. The packing seal wears out relatively quickly and requires frequent replacement; it is also not suitable for high-speed equipment. 4. The dry gas seal provides good performance, but its price is very high.
Compared to the previous answers, I actually lean towards floor 8
Reply to 8# Yihu Xiangming: Hello, my new equipment has not yet been put into operation. The parameters set for the air compressor are a sealing air pressure of 3 kPa and an inlet pressure of 0.18 MPa for the bearing lubricant. Is this situation an isolated case or are the parameters incorrect?
What’s there to worry about if a small amount of air gets into the oil system? Isn’t there nitrogen protection in the email as well? He can expel this portion of air; the dry gas seal is completely leak-proof. However, isolation gas will enter the bearings, and dry gas seals are generally used for compressing high-pressure, toxic media. Nitrogen is used in all cases.