Device for preparing liquefied natural gas by using pressure energy and cold energy of natural gas

Abstract

The invention discloses a device for preparing liquefied natural gas by using pressure energy and cold energy of natural gas. The device for preparing the liquefied natural gas by using the pressure energy and the cold energy of the natural gas comprises an emergency cutoff valve, a natural gas filter A, a natural gas expansion machine, a first level oil separator A, a second level oil separator A, an oil-oil heat exchanger, an oil rough filter A, an oil pump A, an oil fine filter A, a filter B, a mixed refrigerant compressor, a first level oil separator B, a second level oil separator B, a third level oil separator, an active carbon filter, an oil rough filter B, an oil pump B, an oil fine filter B, a gas-gas heat exchanger, a natural gas pretreatment unit, a cold box, an air vaporizer A,an air vaporizer B, a BOG (boil-off gas) compressor, a first level oil-gas separator C, a second level oil-gas separator, an oil fine filter C, an oil pump C and an oil rough filter core C. Comparedwith the prior art, the device for preparing the liquefied natural gas by using the pressure energy and the cold energy of the natural gas has he advantages of solving the problems that pressure energy and cold energy which are obtained after pressure regulation of an existing natural gas pressure regulation station cannot be utilized, and simultaneously a large amount of the natural gas need to be wasted for performing combustion heat replenishment.

Description

technical field [0001] The invention relates to the technical field of residual pressure power generation and cold energy utilization, in particular to a device for producing liquefied natural gas by utilizing natural gas pressure energy and cold energy. Background technique [0002] The natural gas in the national natural gas pipeline network always maintains a relatively high pressure during pipeline transportation, and its pressure is generally around 10MPa. The natural gas from the national natural gas pipeline network is transported to the pipeline networks of major cities and industrial users. After the city gate station of the big city pipeline network adjusts the pressure to 0.4MPa, it is delivered to the end user. During the depressurization process of the natural gas pressure regulating station, there is huge pressure energy and cold energy that can be used. At the same time, the temperature of the natural gas in the pipeline after decompression is lower than -20 ...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the above technical defects, provide a device for producing liquefied natural gas by utilizing the pressure energy and cold energy of natural gas, and solve the problem that the pressure energy and cold energy of the natural gas pressure regulating station in the prior art cannot be utilized after pressure regulation. At the same time, a large amount of natural gas needs to be wasted for combustion and supplementary heat

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