Cogeneration of electricity and refrigeration by work-expanding pipeline gas

Claim 1

The process for the cogeneration of electricity and commercially saleable refrigeration by expanding pressurized pipeline gas with the performance of work which comprises: injecting methanol into said pipeline gas; passing said pipeline gas containing said methanol through a turbo-expander coupled to an electrical generator to reduce the pressure of said pipeline gas at least 100 psi but not reducing said pressure enough to drop the temperature of the resulting cold expanded gas below about -100° F., said electrical generator simultaneously yielding said electricity; separating aqueous methanol condensate from said cold expanded gas and introducing said condensate into a distillation column for separation into discard water and recycle methanol for injection into said pipeline gas; recovering said saleable refrigeration from said cold expanded gas; adding reboiler heat to said distillation column in an amount required to warm said expanded gas after the recovery of said saleable refrigeration therefrom to a predetermined temperature above 32° F.; and passing said expanded gas after the recovery of said saleable refrigeration therefrom in heat exchange with methanol vapor rising to the top of said distillation column to condense said methanol vapor so that liquid methanol is obtained partly for reflux in said distillation column and partly for said recycle methanol and simultaneously said expanded gas is warmed to said predetermined temperature above 32° F.