Liquefied natural gas and hydrocarbon gas processing

Abstract

A process for the recovery of heavier hydrocarbons from a liquefied natural gas (LNG) stream and a hydrocarbon gas stream is disclosed. The LNG feed stream is heated to vaporize at least part of it, then expanded and supplied to a fractionation column at a first mid-column feed position. The gas stream is expanded and cooled, then supplied to the column at a second mid-column feed position. A distillation vapor stream is withdrawn from the fractionation column below the mid-column feed positions and directed in heat exchange relation with the LNG feed stream, cooling the distillation vapor stream as it supplies at least part of the heating of the LNG feed stream. The distillation vapor stream is cooled sufficiently to condense at least a part of it, forming a condensed stream. At least a portion of the condensed stream is directed to the fractionation column as its top feed. A portion of the column overhead stream is also directed in heat exchange relation with the LNG feed stream, so that it also supplies at least part of the heating of the LNG feed stream as it is condensed to form a 'lean' LNG stream. 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.