| 摘要 |
1,180,496. Natural gas liquefaction process. CHICAGO BRIDGE & IRON CO. 20 Feb., 1968 [27 July, 1967], No. 8221/68. Heading F4P. Liquefaction of compressed natural gas containing carbon dioxide, methane and higher hydrocarbons is effected by dividing the feed gas into first and second streams 12, 30 cooling the first stream by work-expansion in a turbine 18 without solidification of carbon dioxide, absorbing carbon dioxide at 31 from the second stream 30, cooling the latter to effect partial liquefaction in heat exchangers 24, 23, 22 in countercurrent to said expanded first stream, separating at 62 an impure liquid fraction containing heavy hydrocarbons from said cooled second stream, expanding this separated liquid at a valve 64 and using the cold so produced in a terminal exchanger 67 to liquefy vapour withdrawn from the separator 62 through a line 70. Most of the liquid methane is expanded at a valve 72 into a storage tank 74 at about atmospheric pressure whilst a minor portion of liquid methane is expanded at a valve 77 and joins the cold vapour leaving valve 64. A phase separator 44 is interposed in the second stream between exchangers 24, 23 and separated higher hydrocarbons are expanded at a valve 48 whilst a portion of the uncondensed vapour is withdrawn through a line 45, expanded in a turbine 37 and the two portions combined in a line 50 with the aforementioned expanded portions from separator 62. Effluent from tank 74 is compressed at 79, added to the first feed stream leaving turbine 18 and is then warmed in exchangers 22, 23, 24, 13 and fed into a consumer line 26. |
