NATURAL GAS LIQUEFACTION PROCESS USING LOW LEVEL, HIGH LEVEL AND ABSORPTION REFRIGERATION CYCLES

摘要

The present invention is an improvement to a liquefaction process for natural gas, wherein refrigeration for the liquefaction process is provided by two closed-loop refrigeration cycles. The first or low level refrigeration cycle uses either a mixed refrigerant or a single component refrigerant as the heat pump fluid, and the second or high level refrigeration cycle uses a mixed (multicomponent) refrigerant as the heat pump fluid. In the liquefaction process the second or high level refrigeration cycle cools the low level heat pump fluid. The low level refrigeration cycle cools and liquefies the cooled natural gas feed. The improvement to the process is the use of an absorption refrigeration cycle to precool the natural gas feed, the low level heat pump fluid, the high level heat pump fluid and, if required, the deep flash recycle. Heat to drive the absorption refrigeration cycle is provided by the exhaust gas from one or more drives for the compressors in the process.