Process for depleting carbon dioxide content in a natural gas feedstream containing hydrocarbons

Abstract

The present invention relates to a process and apparatus for depleting carbon dioxide content in a natural gas feedstream containing ethane and C3+ hydrocarbons to an amount at or near sales gas specification and separating the C3+ hydrocarbons therefrom. The process involves cooling the natural gas feed stream under a first set of temperature and pressure conditions arranged to produce a liquid stream of carbon dioxide, ethane and C3+ hydrocarbons and a gas stream having a reduced carbon dioxide concentration. The liquid stream is separated from the gas stream, and C3+ hydrocarbons may be separated therefrom. The gas stream is then cooled under a second set of temperature and pressure conditions arranged to produce a sweetened natural gas stream and a second liquid containing liquid carbon dioxide and / or carbon dioxide solids. The sweetened natural gas stream is separated from the second liquid. The process is particularly effective for a natural gas feedstream with a carbon dioxide content > 20% and a combined ethane and C3+ content > 5%, and is able to reduce the carbon dioxide content to < 5%.