Propane pre-cooling mixed refrigerant liquefaction system applied to base-load type natural gas liquefaction factory

Abstract

The invention discloses a propane pre-cooling mixed refrigerant liquefaction system applied to a base-load type natural gas liquefaction factory. The system comprises a pre-cooling cold box, a liquefaction cold box, a copious cooling cold box, a propane pre-cooling circulation mechanism and a mixed refrigerant liquefaction copious cooling circulation mechanism. Due to the adoption of the propane pre-cooling mixed refrigerant liquefaction system, natural gas which is qualified after pretreatment can be introduced into the mixed refrigerant liquefaction copious cooling circulation mechanism to be further cooled by a mixed refrigerant after being precooled by the propane pre-cooling circulation mechanism and is finally introduced into a liquefied natural gas (LNG) storage tank through throttling; the propane pre-cooling circulation mechanism and a flow channel of the pre-cooling cold box are subjected to heat transfer through liquid propane in a propane gas-liquid separation tank by a thermal siphon principle, and propane which is subjected to heat transfer and is gasified in the pre-cooling cold box is returned to a corresponding inlet of a propane compressor for gradual compression until a final-stage outlet is reached so as to finish a circulation process; and when used for liquefying natural gas, the system provided by the invention is convenient to operate, is safe and reliable and has high efficiency and high adaptability, equipment investment is reduced, flow control automation is improved, and driving time is shortened.

Description

technical field [0001] The invention relates to a propane precooling mixed refrigerant liquefaction system applied to a base-load type natural gas liquefaction plant, belonging to the technical field of natural gas liquefaction. Background technique [0002] At present, the common domestic natural gas liquefaction technology is mostly nitrogen expansion and single-stage mixed refrigerant cycle refrigeration process, which can only be applied to small-scale LNG plants. Among the liquefaction technologies used in base-load natural gas liquefaction plants abroad, kettle or shell-and-tube heat exchangers are often used for propane precooling, which has poor heat transfer performance, resulting in waste of equipment investment, and the power consumption of traditional three-stage propane precooling systems Larger, the use of coiled heat exchangers for cryogenic cooling results in high investment in equipment and high dependence on imported equipment. Contents of the invention ...

AI Technical Summary

Problems solved by technology

In foreign liquefaction technologies used in base-load natural gas liquefaction plants, tank or shell-and-tube heat exchangers are often used for propane pre-cooling, which has poor heat transfer performance, resulting in waste of equipment investment, and the power consumption of traditional three-stage propane pre-cooling systems Larger, the use of coiled heat exchangers for cryogenic cooling results in high equipment investment and high dependence on imported equipment

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