| 摘要 |
A process for the recovery of ethane, ethylene, propane, propylene, and heavier hydrocarbons from a liquefied natural gas (LNG) stream and a hydrocarbon gas stream is disclosed. The LNG feed stream is divided into two portions. The first portion is supplied to a fractionation column at a first upper mid-column feed point. The second portion is directed in heat exchange relation with a first portion of a warmer distillation stream rising from the fractionation stages of the column, whereby the LNG feed stream is partially heated and the distillation stream is totally condensed. The condensed distillation stream is divided into a "lean" LNG stream and a reflux stream, whereupon the reflux stream is supplied to the column at a top column feed position. The second portion of the LNG feed stream is heated further to partially or totally vaporize it and thereafter supplied to the column at a first lower mid-column feed position. The gas stream is divided into two portions. The second portion is expanded to the operating pressure of the column, then both portions are directed in heat exchange relation with the lean LNG stream and the second portion of the warmer distillation stream, whereby both portions of the gas stream are cooled, the lean LNG stream is vaporized, and the second portion of the distillation stream is heated. The first portion of the gas stream, which has been cooled to substantial condensation, is supplied to the column at a second upper mid-column feed point, and the second portion is supplied to the column at a second lower mid-column feed point. The quantities and temperatures of the feeds to the column are effective to maintain the column overhead temperature at a temperature whereby the major portion of the desired components is recovered in the bottom liquid product from the column. |
