Hybrid condensation-absorption olefin recovery

Abstract

A hybrid condensation-absorption process and unit is disclosed for the recovery of olefins. A mixed-component stream containing hydrogen, methane and olefins is compressed and refrigerated against propylene refrigerant to partially condense the stream. The condensate is stripped of volatile components and fed to a fractionation unit such as a deethanizer. The volatile components stripped from the condensate and the non-condensed vapor from the mixed-component stream are fed to a solvent absorption unit to remove olefins which are absorbed in the solvent. The olefins-rich solvent is regenerated to recover olefins and lean solvent. The lean solvent is recirculated to the absorption unit. The olefins recovered from regeneration of the solvent are fed to the fractionation unit along with the pre-stripped condensate. Vapor from the absorption unit is cryogenically processed to recover a crude hydrogen product, a fuel gas product and residual olefins which can be recycled to the absorption unit. The hybrid process eliminates the need for low temperature (ethylene) refrigeration equipment, generally required by conventional condensation-based olefins recovery technology, and substantially reduces the solvent recirculation rate to the absorption unit and eliminates hydrogen expansion as compared to conventional absorption-based technology.