Hydrocarbon gas processing

Abstract

A process for the recovery of ethane and heavier hydrocarbon components from a hydrocarbon gas stream is disclosed. The stream is divided into first and second streams. The first stream is cooled to condense substantially all of it and is thereafter expanded to a pressure below that of the distillation column. After expansion, the cooled first stream is directed in heat exchange relation with a warmer distillation stream rising from fractionation stages of the distillation column. The warmed first stream is then separated to provide a cold vapor and a liquid stream. The liquid is supplied to the column at a first mid-column feed position and the cold vapor is supplied to the column at a second mid-column feed position. The second stream is expanded to the column pressure and is then supplied to the column at a third mid-column feed position. The distillation stream is cooled by the first stream sufficiently to partially condense it . The partially condensed distillation stream is then separated to provide volatile residue gas and a reflux stream feed. The reflux stream feed is supplied to the column at a top column feed position. In instances where the second stream is expanded in a work expansion machine, any condensation formed prior to work expansion is combined either in whole or in part with the first stream prior to cooling and/or expansion, or supplied either in whole or in part to the column as a condensed stream at a fourth mid-column feed position, or some combination thereof. The temperatures of the feeds to the column are effective to maintain the column overhead temperature at a temperature whereby the major portion of the C.sub.2 + components is recovered.