Reliquefaction device for boil-off gas from liquefied natural gas vehicle gas filling station

Abstract

The invention relates to a reliquefaction device for boil-off gas from a liquefied natural gas vehicle gas filling station, which belongs to the technical field of low-temperature liquefied gas storage and transportation. The reliquefaction device comprises a storage tank of the gas filling station, a compressor, a cooler, a heat exchanger, a throttle valve, a gas-liquid separator, an expansion machine and a submerged cryogenic pump. The reliquefaction device takes BOG which needs to be liquefied as a refrigerant and adopts the single-stage compression and the single-stage expansion and throttling refrigeration method, thereby leading the BOG to achieve the liquefaction purpose. When the pressure of a system reaches the designed control value, the reliquefaction device is started automatically for liquefying one part of the redundant BOG and further reducing the temperature and the pressure in the system, when the pressure of the system is reduced to the required value, the reliquefaction device is stopped automatically. The reliquefaction device can solve the BOG emptying problem of the LNG filling station through reliquefaction of the BOG. The reliquefaction device can reduce the potential safety hazard caused by BOG emptying, and have significant social benefits and economic benefits for protecting the environment and reducing the waste of resources.

Description

technical field [0001] The invention relates to a reliquefaction device for boil-off gas (BOG) of liquefied natural gas (LNG), in particular to a reliquefaction device for boil-off gas of LNG vehicle filling stations. The invention can also be used for BOG reliquefaction in other types of LNG storage facilities, and belongs to the technical field of low-temperature liquefied gas storage and transportation. Background technique [0002] As a clean fuel, LNG is one of the most ideal alternative fuels for automobiles. It is used in buses and heavy vehicles, and its economic and social benefits are very significant. LNG is a low-temperature liquid formed by cooling natural gas to the dew point temperature after purification, which is convenient for storage and transportation. When LNG is used as vehicle fuel, it is stored in the low-temperature storage tank of the gas filling station, and can be refueled at any time for vehicles that need to be refueled. [0003] The temperatu...

AI Technical Summary

Problems solved by technology

In the existing technology, the traditional natural gas liquefaction adopts the low-temperature liquefaction method, and the low-temperature generation methods include cascade, multi-stage expansion, and mixed refrigerant cycle refrigeration methods, and the system is relatively complicated.

Moreover, they are all produced on a large scale. There is currently no corresponding device for BOG liquefaction at the scale of gas filling stations.

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