| 摘要 |
1291467 Natural gas liquefaction processes; refrigeration AIR PRODUCTS & CHEMICALS Inc 5 Nov 1969 [19 May 1969] 54146/69 Headings F4P and F4H In a process for liquefying natural gas the feed stream is first cooled in heat exchange with a single component refrigerant and then by heat exchange with a multicomponent refrigerant. Feed gas, free of CO 2 , enters the system via line 10, is passed through heat exchanger 12 and then to a separator 14 from which condensed water is removed via line 16. The gaseous phase is fed by line 18 to either of two driers 20, cooled in heat exchanger 24, and fed into a benzene scrub column 28 wherein the heavier hydrocarbons are condensed and removed via line 30. The feed gas stream passes from the column via line 34 to exchanger 36, is partially condensed, and fed to a separator 38; the liquid phase is used to supply reflux for column 28 whilst the gas is liquefied and subcooled in tube circuits 48 and 54 of a two zone heat exchanger 50, and stored. Exchangers 12, 24 and 36 are cooled by a single component refrigerant, such as propane or propylene supplied by compressors 60 and 62. The refrigerant is expanded at valve 66 into exchanger 12, vaporized refrigerant is returned to compressor 62 and liquid passed via lines 70, 72 and expansion valve 72 to exchanger 24. Any vapour produced is recycled to the compressor whilst the liquid is used in exchanger 36. The multicomponent refrigerant, consisting of nitrogen, propane, ethane and methane, is compressed at 100 and 102, and passed through heat exchangers 86 and 88 which are cooled by refrigerant liquid from exchanger 12 supplied via lines 70 and 90. The partly liquefied refrigerant is passed to a separator 110 and the liquid phase supplied via lines 112, 114 expansion valve 116, line 118 and spray header 52 to the zone exchanger 50. The gaseous phase is liquefied in line 122, subcooled in line 124, expanded at valve 128 and sprayed into exchanger 50 from header 56. Phase separators may be provided in lines 118 and 130, the vapour being injected into the column 50 adjacent headers 52 and 56. Refrigerant make up lines 97 and 140 are provided. |
