Liquefaction unit in vehicle-mounted mobile oilfield vent gas recovery system and liquefaction method thereof

Abstract

The invention relates to a liquefaction unit in a vehicle-mounted mobile oilfield vent gas recovery system and a liquefaction method thereof. The liquefaction unit comprises a precooling heat exchanger, a cryogenic heat exchanger, a liquefaction heat exchanger, a first-stage separator, a second-stage separator, a third-stage separator, a normal-temperature separator, a mixed hydrocarbon separatorand a closed mixed refrigerant three-stage throttling refrigeration device. A bottom liquid outlet of the mixed hydrocarbon separator is connected with a mixed hydrocarbon product conveying pipeline.The closed mixed refrigerant three-stage throttling refrigeration device provides cooling capacity for the pre-cooling heat exchanger, the cryogenic heat exchanger and the liquefaction heat exchanger.The liquefaction unit adopts the first-stage separator, the second-stage separator, the third-stage separator, the normal-temperature separator and the mixed hydrocarbon separator to separate a liquid mixed hydrocarbon product and a liquid natural gas product. The product recovery rate is increased, the emission of oilfield vent gas is reduced, a traditional mixed hydrocarbon recovery rectifyingtower is canceled, the height of low-temperature equipment is reduced, and the design, manufacturing and application of a vehicle-mounted mobile low-temperature cold box skid are realized.

Description

technical field [0001] The invention relates to the technical field of processing oilfield air, in particular to a liquefaction unit and a liquefaction method in a vehicle-mounted mobile oilfield air recovery system. Background technique [0002] Oil field vent air refers to the vent gas rich in methane, ethane, propane and other hydrocarbons produced during the oil production process, and it is a resource that can be recycled. Because the air released from oil fields is relatively scattered, the gas volume is small and unstable, and conventional pipeline transportation is used, the investment cost is high and the economy is poor. Therefore, most of the air released from oil fields is directly discharged and burned, which not only wastes resources, but also causes environmental pollution, which is not in line with the national standard Safety and environmental requirements. [0003] At present, there are related recovery systems designed at home and abroad to recycle oilfie...

AI Technical Summary

Problems solved by technology

Because the air released from oil fields is relatively scattered, the gas volume is small and unstable, and conventional pipeline transportation is used, the investment cost is high and the economy is poor. Therefore, most of the air released from oil fields is directly discharged and burned, which not only wastes resources, but also causes environmental pollution, which is not in line with the national standard Safety and environmental requirements

[0003] At present, there are related recovery systems designed at home and abroad to recycle oilfield air, such as the patent with the authorized announcement number CN209872346U: a separation and synthesis device for realizing the in-situ conversion of oilfield associated gas, which is used for desulfurization of oilfield associated gas , conversion and separation to obtain CO, hydrogen and synthesis gas, but this device is not suitable for recovering mixed hydrocarbons and liquefied natural gas in the oil field vent air, and the liquefaction effect of recovering mixed hydrocarbons and liquefied natural gas from oil field vent air is not good, so Affect the quality of liquefied products, therefore, it is necessary to design a liquefaction unit and method in a vehicle-mounted mobile oilfield vent air recovery system with good liquefaction effect

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