Abstract: Refrigerating unit is a key equipment in polyolefin industry which recovers the copolymer and isopentane in the gas discharged from the reactor. The operating condition of the refrigerating unit directly affects the unit consumption of materials. There are many factors affecting the refrigeration capacity of refrigeration units. This paper analyzes and studies the problems of expansion valve failure and improper superheat setting, suction filter blockage, water contained in the system, excessive or insufficient refrigerant charging, load control system failure, leakage between high and low pressure systems, oil film generated by heat exchanger, changes in process conditions. It proposes some relevant preventive measures so as to avoid the decrease of refrigeration capacity of refrigeration units caused by the above reasons and ensure the safe, efficient and stable operation of the refrigerating units.

Key words: refrigerating unit, expansion valve, refrigerant, control system, refrigeration capacity