SYSTEM AND METHOD FOR LIQUEFYING NATURAL GAS USING SINGLE MIXED REFRIGERANT AS REFRIGERATION MEDIUM

摘要

A system and a method for liquefying natural gas using single mixedrefrigerant asrefrigeration medium are provided. The system comprises a two-stage mixedrefrigerant compressor (1) driven by a motor, two coolers (21, 22), a liquidpump (4),three gas-liquid separators (31, 32, and 6), two throttling devices (51, 52),a plate-finheat exchanger group (7) and a LNG storage tank (8). The method comprises thefollowing steps: the mixed refrigerant is compressed step by step by using thetwo-stage mixed refrigerant compressor (1), separated step by step, and gas-phase andliquid phase mixed refrigerant streams obtained from the separation flow intodifferent passages of the heat exchanger group(7) respectively for throttlingand heatexchanging. Heat exchange curves of cold fluid and hot fluid in the whole heatexchange process match with each other better by using two-stage heatexchange,thereby flow of the mixed refrigerant is reduced effectively.