Patent attributes
Disclosed are a method and system for sweetening a raw natural gas feed stream using a multi-stage membrane separation process, and in embodiments a two-stage membrane separation process. The method and system also include use of a gas turbine which operates with an impure fuel gas stream (such as in the sense of having a relatively high CO2 and H2S acid gas contaminant content) as derived from a permeate gas stream obtained in at least the second stage of a membrane separation process, or later stages if more than two stages are employed. In embodiments, the gas turbine is coupled with an electrical generator, which generates electrical power that drives a compressor for the second stage (or higher) of the membrane separation process, as well as other process equipment associated therewith, such as air coolers and process pumps. Alternatively, the gas turbine can be coupled mechanically to the compressor employed. In other embodiments, the power generated by the turbine generator combination can be exported to a local power grid. In other embodiments, the turbine generator is a micro-turbine generator (MTG) which can advantageously be used in applications where space is limited, such as an offshore platform or other oil/gas production facility or on board a floating vessel.
