| 摘要 |
1,170,329. Liquefaction and re-vaporization of natural gas. V. C. WILLIAMS and O. H. SIMONDS. 2 Nov., 1967 [2 Nov., 1966; 20 July, 1967], No. 49800/67. Heading F4P. Liquefaction of compressed natural gas prior to transport in a heat-insulated container from a field site to a market site where it is re-vaporized in heat exchange with a gaseous refrigerant comprising mostly nitrogen undergoing liquefaction is effected by heat exchange in a path 34, Fig. 1, with liquid nitrogen in a path 24 and having been transported from the market site in containers previously occupied by L.N.G.; the liquid nitrogen prior to passage through path 24 being pressurized by a pump 18 and the nitrogen gas leaving pass 24 being work expanded in a turbine 26 and passed through a further path 29 thereby serving to assist liquefaction of feed natural gas. At the market site L.N.G. is withdrawn from the containers and is vaporized by passage through a path 46, Fig. 2, of a heat exchanger 44 in indirect countercurrent flow in a path 50 of compressed gaseous nitrogen which is partly liquefied, expanded to about atmospheric pressure into a phase separator 62; the liquid nitrogen being withdrawn through a line 64 leading to a transport container 16 whilst cold gaseous nitrogen after recovery of cold in an exchanger 56 is recompressed at 58 and returned to the inlet 48 of path 50. In a modification the compressed natural gas having been liquefied at the field site is expanded in a turbine which drives the pump for pressurizing the liquid nitrogen, and the nitrogen expansion turbine drives the compressor for the feed natural gas and at the market site L.N.G. is split into a first stream which is vaporized by heat exchange with gaseous nitrogen and then compressed and discharged into a product line, and into a second stream which is pressurized by a pump, vaporized, turbine expanded and added to the first stream in the product line; the turbine being used to drive the compressor. |
