LIQUEFACTION METHOD Russian patent published in 1999 - IPC

FIELD: gas production method. SUBSTANCE: according to method, liquefaction of natural gas is performed by passing natural gas through series of successively installed heat exchangers in counterflow with respect to gaseous cooling agent circulating in cycle of working expansion. Working expansion cycle includes compression of cooling agent, separation and cooling of agent for creation of at least first and second flows of cooled agent. Then follows is isoentropic expansion of first flow of cooling agent to maximal low temperature, and isoentropic expansion of second flow of cooling agent to intermediate temperature of cooling agent. Performed is delivery of cooling agent in first and second flow into corresponding heat exchanger for cooling of natural gas down to respective ranges of temperature. Cooling agent of first flow is expanded isoentropically to pressure which is at least 10 times higher than total pressure drop of cooling agent in first flow of cooling agent in succession of heat exchangers, and this pressure stays within range of 1.2-2.5 MPa. Application of aforesaid method allows for performing liquefaction of natural gas directly at recovering gas at sea. EFFECT: higher efficiency. 17 cl, 13 dwg