On the usage of propylene gas circulation compressors in domestic PP plants

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Dear all**, I would like to know if any of you have labyrinth-type propylene recycle gas compressors for domestic PP plants. How is your usage? We are using a labyrinth-type compressor manufactured by a domestic company, and its performance is not very satisfactory. The main issues are as follows: 1. Hydrocarbons tend to enter the crankcase initially, which lowers the flash point and viscosity of the lubricating oil, preventing long-term operation. Post-modification: Zhongti added an oil drainage line, replaced the inert gas with propylene gas, and changed the lubricating oil from L-DAB150 to GeGao 150 (synthetic oil). It works normally after running. 2. The compressor contains a large amount of oil and dust, and this problem cannot be completely resolved. After taking measures, the situation improved slightly but not significantly: a new filter F303 (with a precision of 10 UM) was added after D304. The several buffer tanks of the compressor and D304 are drained regularly. When producing products with high and low melt indices, the oil discharge is minimal; it is slightly higher for those with high melt indices. 3. The performance of the air valve has been poor since 2016 (it was not ideal even before, with a maximum lifespan of nearly 4 months); now its lifespan is around half a month to 2 months. Domestic gas valves or domestically repaired gas valves. 16 years ago, when gas valves were disassembled, inspected, and replaced, springs and valve plates rarely broke, but this phenomenon has occurred frequently since this year. The device load also increased last year; it was generally 80–95% last year, while this year it is 90–110%. We believe that the operating condition of the gas valve is also related to the load; an increase in the circulation rate leads to an increase in the total amount of impurities in the circulating gas per unit time, and it is possible that there are quality issues with the gas valve. Some modifications have been made to the currently used domestic new gas valves, and their effectiveness remains to be tested. I would like to ask the experts: how is your operation going? Has a situation like ours occurred before? How was it solved?