Patent ID: 7429686

Claim:
A process for recovering olefins from a feed stream, comprising: supplying the feed stream at a primary distillation pressure, including if required compressing the feed stream in a primary compression stage; distilling the feed stream at the primary distillation pressure in a primary distillation zone to obtain a primary overhead vapor stream enriched in ethylene and one or more ethylene-lean bottoms streams; chilling the primary overhead vapor stream at a pressure less than 24.5 kg/cm 2 in a first cooling stage to recover a first partial condensate stream and a first-stage vapor effluent; refluxing the primary distillation zone with at least a portion of the first partial condensate stream; further chilling the first-stage vapor effluent to recover at least a second partial condensate stream and a second-stage vapor effluent; feeding the at least second partial condensate stream and any remaining portion of the first partial condensate stream to a demethanizer to recover a methane-rich overhead stream and a bottoms stream essentially free of methane and lighter components; fractionating the bottoms streams from the primary distillation zone and the demethanizer into respective streams consisting essentially of hydrocarbons selected from the group consisting of ethylene, ethane, propylene, propane, C4's, C5+ and combinations thereof; further chilling the second-stage vapor effluent in a cold section and phase-separating the resulting mixed vapor-liquid stream in one or more stages to obtain additional condensate and a vapor tail gas stream essentially free of ethylene, wherein the additional condensate is vaporized to a relatively lower pressure to provide refrigeration for the condensation and to form a low pressure recycle vapor stream.