scroll compressor, oil circuit, compression heat, self-balancing, natural gas
Owing to its reliable operation and low maintenance requirement, the scroll compressor has a potential application for oil and gas industry, e.g. the natural gas production for gas wells with low production and boil-off-gas recovery for gasoline filling stations. Though millions of scroll compressors are put into the refrigeration and air conditioning market each year, a much smaller number of such equipments have been used in the field of oil and gas production. This should be attributed to much larger quantity of compression heat for the natural gas compressor due to higher pressure ratio and larger isentropic exponent, which can not be taken way from oil circulation with traditional oil circuit design typical of refrigeration application. This paper presents an experimental investigation of a horizontal hermetic scorll compressor with novel oil circuit design. The oil was not injected but carried into the compression chamber by the suction gas to remove the compression heat. The oil circuit was so designed that the high pressure oil from the oil-gas separator was cooled, throttled into low pressure, and then stored in the horizontal motor casing, where the oil together with the suction gas entered the compression chamber. Owing to self-balancing, the oil level in the casing was kept constant whatever the operating conditions could be. Based on the novel oil circuit design, a vertical scroll compressor for commercial refrigeration was modified into a horizontal prototype compressor for natural gas compression. The prototype compressor was validated under a wide range of operating conditions in the closed loop test system. Its thermodynamic performances including flow rate and power consumption were tested under various working conditions. The results showed that the compressor could work reliably as the suction pressure ranged from 0 MPa(Gauge) to 0.25 MPa, and with one stage compression the maximal discharge pressure reached 3 MPa as the suction pressure was kept at 0 MPa.