Patent ID: 6244070
Filing Date: 2001-06-12
Classification: F25J

Abstract:
A process for recovering components of a hydrocarbon-containing feed gas via a cryogenic distillation column wherein its reflux components are cryogenically generated by a separate lean reflux absorber, comprising:a) deriving a top feed portion and a bottom feed portion to said lean reflux absorber by dividing a feed gas stream into a top feed portion, a bottom feed portion, and a first gas portion, and thereafter cooling and separating said first gas portion into a first liquid phase comprising condensed components and a main vapor portion;b) condensing said top feed portion and thereafter introducing it to the top of said lean reflux absorber comprising one or more mass transfer stages;c) introducing said bottom feed portion to said lean reflux absorber at a location below said condensed top feed portion;d) rectifying within said lean reflux absorber to produce a lean vapor phase from an upper region of said lean reflux absorber, and a bottom fluid stream comprising the remaining components from the bottom of said lean reflux absorber;e) condensing said lean vapor phase to form a lean reflux stream for top feed to said cryogenic distillation column;f) expanding and lowering the pressure of:(i) said lean reflux stream and supplying it as reflux to the top of said cryogenic distillation column,(ii) said bottom fluid stream and supplying it as a first middle feed to a middle region of said cryogenic distillation column at a point below top reflux,(iii) said main vapor portion and supplying it as a second middle feed to the middle region of said cryogenic distillation column at a point below the top reflux and at least the same as or above the first liquid phase, if present, and(iv) said first liquid phase, if present, and supplying it as a third middle feed to the middle region of said cryogenic distillation column at a point not higher than the second middle feed, andg) recovering natural gas liquid product from the bottom of said cryogenic distillation column.