Patent ID: 6755965
Filing Date: 2004-06-29
Classification: C07C,F25J,Y02P

Abstract:
A process for recovering ethane from a methane, ethane and propane containing gas stream comprising:(a) providing the hydrocarbon gas stream comprising from about 50% to about 75% by mole methane, from about 15% to about 40% by mole ethane and from about 1% to about 4% by mole propane; (b) cooling the hydrocarbon gas stream to provide a partially condensed feed stream; (c) separating said partially condensed feed stream into a vapor hydrocarbon feed stream and a condensed liquid hydrocarbon feed stream; (d) providing a cryogenic heat exchanger; (e) cooling the vapor hydrocarbon feed stream in a the cryogenic heat exchanger by heat exchange with a first cooling source, a second cooling source and a third cooling source to form a cooled and substantially condensed hydrocarbon feed stream, wherein said first cooling source is said condensed liquid hydrocarbon feed stream; (f) distilling said cooled and substantially condensed hydrocarbon feed stream and said condensed liquid hydrocarbon feed stream in a demethanizer column to form a methane-rich stream and an ethane/propane-rich stream, wherein said methane-rich stream is said second cooling source; (g) compressing said methane-rich stream to form a compressed methane-rich stream; (h) cooling said compressed methane-rich stream to form a compressed methane-rich stream; (i) turboexpanding said compressed methane-rich stream to a lower pressure to provide said third cooling source for said cryogenic heat exchanger; (j) distilling said ethane/propane-rich stream in a de-ethanizer column to form an ethane-rich stream and a propane-rich stream; and (k) recovering said ethane-rich stream.