Method for producing liquefied natural gas by multi-component refrigerant double-stage compression

Abstract

Provided is a method for producing liquefied natural gas by multi-component refrigerant two-stage compression. The method includes two multi-component refrigerant compression cycles, the refrigerant in a first cycle is called a pre-cooling refrigerant, the refrigerant in a second cycle is called a cryogenic refrigerant; the pre-cooling refrigerant returns to an ice chest after passing through a pre-cooling compressor, a cooler, a buffer tank, the ice chest, a throttle valve and a gas-liquid separation tank, and then returns to the pre-cooling compressor; the cryogenic refrigerant returns to the ice chest after passing through a cryogenic compressor, the cooler, the ice chest, the throttle valve and the gas-liquid separation tank, and then returns to the cryogenic compressor; and natural gas is cooled after heat transfer of the ice chest and the refrigerants and finally becomes the liquefied natural gas. The natural gas is liquefied by two independent multi-component refrigerant compression cycles, and composition and content of the two multi-component refrigerants are different, so that the method is wide in application range to raw material natural gas, high in operation flexibility and high in liquefying efficiency. Besides, the method is simple in liquefying process, low in investment cost, and is applicable to liquefied natural gas factories in various scales.

Description

technical field [0001] The invention relates to a method for producing liquefied natural gas, more specifically, the invention relates to a method for producing liquefied natural gas by using natural gas, coal bed methane or other methane-rich gases as raw materials. Background technique [0002] Natural gas is a clean, efficient and safe energy. In recent years, it has been paid more and more attention by various countries, and the trade volume of natural gas in the world has also increased rapidly. However, for cross-sea trade and remote distance transportation, it is neither economical nor convenient to transport gaseous natural gas. The raw material gas containing natural gas, such as: gas field gas, coal bed methane, methane-rich gas, etc., after deacidification, dehydration, mercury removal, heavy hydrocarbon removal, etc., is liquefied at low temperature to become liquefied natural gas. Natural gas is nearly 600 times smaller, which is convenient for storage and tran...

AI Technical Summary

Problems solved by technology

Therefore, the disadvantages of the cascade liquefaction process are: many equipments, complex process, difficult control, poor operation flexibility, high initial investment cost, but its unit energy consumption is low

This process is simple and the number of equipment is small, but when the production scale reaches a large scale, the selection, manufacture and operation of the compressor will be very difficult

When using domestic compressors, this process can only be produced on a small scale, which is not conducive to the localization of this natural gas liquefaction process

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