Carbon deposits in reciprocating presses
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The hydrogen used in the new hydrogen machine of the diesel hydrogenation unit is PSA hydrogen from the dry gas hydrogen production unit. It has been repeatedly found that there is a large amount of carbon deposits in the compressor cylinder. First, I suspected it was dust from PSA, but there was no dust in the press inlet buffer tank. ； I suspected that the oil injection in the cylinder caused carbon deposits, so I stopped the oil injection. After running for two months, I heard the friction sound from the gas tank again. After disassembling the cylinder, I found that there was a lot of carbon deposits mixed with oil stains, which was very strange.: Where does the oil come from? Will the packing oil also leak into the cylinder? There is less carbon deposit on the suction valve, more on the exhaust valve, a layer is attached to the inner wall of the cylinder, there are a few parts on both ends of the piston, and the support ring shows signs of wear. How does carbon deposition occur?
1. There may be leakage at the oil filling point of the packing. I think the main reason for carbon formation is because the outlet valve of a general compressor is at the bottom. Is yours the same? After carbon formation, it is removed through the outlet valve with the air flow, so the outlet valve has more carbon deposits. After carbon is deposited on the surface of the cylinder, the piston ring and the support ring will wear when they contact the cylinder. 2. It is possible that the outlet pipeline is not clean, and the air valve is not tight and the gas carries dust back.
During the reciprocating motion of the piston, the piston rod will entrain a small amount of lubricating oil into the cylinder. As the compression process proceeds, the high temperature causes the oil to carbonize and mostly adhere to the outlet valve. Solution: 1. Adjust the oil filling amount to the appropriate number of drops ； 2. Check the oil scraper packing to reduce the amount of lubricating oil leakage there.
The new hydrogen machine of our hydrotreating unit also has the problem mentioned by the poster. The cylinder is oil-free and after inspection, it was found that the piston ring was seriously worn.
Agree with the 4th floor. Although it is possible for the packing and oil scraper rings to bring oil into the cylinder through the piston rod, the amount is very small. Moreover, the exhaust temperature of the hydrogen compressor is relatively low, generally no more than 150 degrees, which cannot reach the flash point of the lubricating oil (generally greater than 210 degrees). It is most likely that it is left after the plastic piston ring and support ring wear, because a lot of graphite is added to the filled polytetrafluoroethylene.
This post was last edited by gaogezhuang on 2009-8-5 12:15 The exhaust temperature is low, and due to intermittent oil injection, the adhesion layer on the inner wall of the cylinder falls off and forms carbon deposits. Whether the piston ring support ring is worn can be found through inspection after disassembly.: The backup rings have some wear, the piston rings much less.