Ethylene compressor cylinder collision
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We have a Wuxi compressor here (a vertical reciprocating labyrinth compressor); it works fine when tested with air, but it experiences cylinder collision as soon as ethylene is introduced. The dead center clearance has already been adjusted to 2 MM. Today, a cylinder collision occurred again during testing. The Buchhard one next to it doesn’t have any problems at all
Does thermal expansion also need to be considered for reciprocating types? I’m not sure either. The manufacturer has repaired it almost 10 times already. \ud83c\udf1d\ud83c\udf1d The dead zone clearance is already this large. . . Additionally, the crosshead pin shows signs of scuffing
Personal opinion: Ethylene tends to polymerize; as compression takes place, the temperature rises, and the polymerization and coking of ethylene cause the clearance at the dead points to gradually decrease, leading to cylinder collision. It might be necessary to reduce the compression ratio or lower the cooling temperature of the cylinders – I’m not sure if this is correct
Yesterday, the dead center clearance was adjusted to 2.5 MM. As a result, after just 1 minute of operation, there was already a sound of collision with the cylinder. Opening it up, the inside is quite clean.
Check whether the piston nut is loose, whether there are cracks in the piston body, and whether the cylinder liner is loose.
A compressor crash against its cylinder is definitely related to the clearance at the top dead center; I’m not sure whether your compressor is single-acting or double-acting. The allowance for the top dead center clearance is primarily intended to compensate for the difference in thermal expansion between the cylinder block and the piston assembly; therefore, the size of the top dead center is mainly determined by the operating temperature and the degree of expansion of each component. It is recommended to refer to the operating temperature to calculate the expansion difference, as the operating temperatures of air and ethylene may differ. Here, for the horizontal reciprocating type 4M50-144/2.8-26.4 model, the end-stop clearance is 5±0.5 mm. A larger end-stop clearance can affect the flow rate; we can consider machining the cylinder head according to your requirements.
Well, it’s single-acting. Now the dead center clearance has been increased by 1MM. It already seems pretty big. Compared to the previous 1MM
Well, okay. Now the manufacturer has brought in a top expert. After the repairs, the nitrogen test run proceeded normally; no medium has been introduced yet. . .