Investigation of Start Up Process in Oil Flooded Twin Screw Compressors

摘要

Oil injected screw compressors used for air applications and refrigeration are usually installed in simple packagesrnwhich often do not include oil pump for supply of oil to the bearings and the working chamber. The period of an unlubricatedrnoperation depends on the size of the oil system and the length of the discharge piping. When the backrnpressure reaches the chamber pressure, a normal mode of lubrication will start. Due to the lack of lubrication, rotorsrnwill be in direct contact with insufficient or no oil film between them, while the pressure in the compressionrnchamber will increase causing the temperature to rise. The leakage flow will be higher than normal which willrnincrease the overall temperature in the compression chamber. It is expected that some surface damage may occur onrnthe rotors. In a case of a frequent start-stop mode, such operation may cause quick wear and rapid decrease in therncompressor performance. This paper is expected to address such issues and to define a scope of work required tornunderstand the oil flooded compressor process in a transient operation mode. This will allow prediction of wear inrnsuch compressors and will give some insight to the required modifications to prevent these issues and increase therncompressor reliability.