Energy derived from expansion of liquefied gas

900,325. Liquefaction of gases. CONCH INTERNATIONAL METHANE Ltd. Jan. 20, 1961 [Sept. 2, 1960], No. 30348/60. Class 8(2). In a gas e.g. natural methane liquefaction process wherein highly compressed methane issuing from a compressor 2 at say 3,000 p.s.i. is liquefied in exchangers 6, 7 the pressurized liquid methane is passed through a hydraulic motor e.g. a Pelton wheel 8 without any substantial revaporization and is then expanded at a valve 10 into a flash vessel 11 at about 16 p.s.i. from which liquid methane is discharged by a pump 13 into a storage tank 12 and flash-off vapour passes through a line 14 and the exchanger 6. The exchanger 7 is cooled by a closed nitrogen cycle comprising a compressor 19, an ammonia-cooled exchanger 20, an expansion engine 21 and a line 18. The expander 21 and motor 8 assist in driving the compressors 19, 20. Specifications 852,844 and 883,656 are referred to.