Double-refrigerant circulating natural gas liquefaction system based on wound-tube heat exchanger

Abstract

The invention provides a double-refrigerant circulating natural gas liquefaction system based on a wound-tube heat exchanger. The double-refrigerant circulating natural gas liquefaction system is characterized by comprising a precooling level compression module, a precooling level heat exchange module, a copious cooling level compression module and a copious cooling level heat exchange module which are connected, wherein the precooling level compression module comprises buffer tanks, compressors and coolers which are connected in sequence; a precooling refrigerant low-pressure outlet of the precooling level heat exchange module is connected with one of the buffer tanks; a natural gas first-level outlet is connected with a gas-liquid separator; the outlet of one of the coolers is connected with another gas-liquid separator; the copious cooling level compression module comprises buffer tanks, compressors and coolers which are connected in sequence; a copious cooling refrigerant low-pressure outlet of the copious cooling level heat exchange module is connected with one of the buffer tanks of the copious cooling level compression module; a natural gas second-level outlet is connected with the exterior; a natural gas second-level inlet is connected with one of the gas-liquid separators; the outlet of one of the coolers of the copious cooling level compression module is connected with a copious cooling refrigerant first-level inlet; and a copious cooling refrigerant first-level outlet is connected with a gas-liquid separator of the copious cooling level heat exchange module. According to the double-refrigerant circulating natural gas liquefaction system, two-level independent mixed refrigerants circulate and are overlaid, the system process is concise, the structure is compact, the production load operational flexibility is high, the integral machine adopts modularized design, and the system is applicable to offshore flotation natural gas production devices.

Description

technical field [0001] The invention relates to a natural gas liquefaction system, in particular to a natural gas liquefaction system with double refrigerant cycles based on a coiled tube heat exchanger. Background technique [0002] LNG (Liquefied Natural Gas, liquefied natural gas) is to cool the treated gaseous natural gas under normal pressure to -162°C to condense it into liquid. The liquid volume of LNG is about 1 / 600 of its gaseous volume, which greatly saves storage and transportation space and cost, and has the characteristics of large calorific value and high performance. Therefore, LNG is a clean and efficient energy source. [0003] Natural gas liquefaction process mainly includes three types: cascade liquefaction process, mixed refrigerant liquefaction process and liquefaction process with expander. Among them, the cascade liquefaction process unit is too complicated and the investment cost is high, and it is mainly used in the early base-load liquefaction plan...

AI Technical Summary

Problems solved by technology

Although this type of natural gas liquefaction process has a high production capacity, the system process is too complicated, the equipment size is large and the investment cost is high, so it cannot better meet the offshore production conditions

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