A system and method for separating CO.sub.2 from natural gas, which ensure that no clogging or deterioration occurs in a gas separation membrane even after the gas separation membrane is used to remove carbon dioxide from the natural gas under conditions in which the natural gas is pressurized. First, an H.sub.2S remover removes hydrogen sulfide from raw natural gas. Then, a compressor pressurizes the natural gas from which H.sub.2S has been removed. After that, a cooler cools the pressurized natural gas so as to condense components that are a part of the natural gas. A gas/liquid separator removes the condensed components, and a CO.sub.2 separator, including a separation membrane for separating CO.sub.2 removes CO.sub.2 from the natural gas from which the condensed components have been removed. An expander, which shares a drive shaft with the compressor, expands the natural gas from which CO.sub.2 has been removed and recovers energy therefrom.

A methane purification system includes one or more components that cool and compress an input methane-containing gaseous mixture stream to form a first methane-containing gaseous mixture stream. A filter-separator in fluid communication with the one or more components receives the first methane-containing gaseous mixture stream removing water therefrom to form a second methane-containing gaseous mixture stream. An activated carbon station receives the second methane-containing gaseous mixture stream removing hydrogen sulfide therefrom to form a third methane-containing gaseous mixture stream. A methanol scrubber that receives the third methane-containing gaseous mixture stream or an expanded stream therefrom, removing carbon dioxide to form a fourth methane-containing gaseous mixture stream. A final stage separator produces a purified methane stream from the fourth methane-containing gaseous mixture stream or an expanded stream therefrom.

A process and an apparatus are disclosed for a compact processing assembly to remove C.sub.5 and heavier hydrocarbon components from a hydrocarbon gas stream. The hydrocarbon gas stream is expanded to lower pressure and supplied to the processing assembly between an absorbing means and a mass transfer means. A distillation vapor stream is collected from the upper region of the absorbing means and cooled in a first heat and mass transfer means inside the processing assembly to partially condense it, forming a residual vapor stream and a condensed stream. The condensed stream is supplied to the absorbing means at its top feed point. A distillation liquid stream is collected from the lower region of the mass transfer means and directed into a second heat and mass transfer means inside the processing assembly to heat it and strip out its volatile components.

The present techniques are directed to a system and method for generating power and recovering methane from methane hydrates. The system includes a low emissions power plant configured to generate power, wherein an exhaust gas from the low emissions power plant provides a gas mixture including nitrogen and carbon dioxide. The system also includes a methane recovery system configured to recover methane from methane hydrates by injecting the nitrogen and the carbon dioxide from the gas mixture into the methane hydrates.

Gas processing plants and methods are contemplated in CO.sub.2 is effectively removed to very low levels from a feed gas to an NRU unit by adding a physical solvent unit that uses waste nitrogen produced by the NRU as stripping gas to produce an ultra-lean solvent, which is then used to treat the feed gas to the NRU unit. Most preferably, the physical solvent unit includes a flash unit and stripper column to produce the ultra-lean solvent.

The invention relates to a method for the treatment of natural gas containing carbon dioxide, methane and paraffins. The method comprising: a step of extracting the paraffins from the natural gas in a paraffin-removal column, and a step of separating the carbon dioxide and the methane in a distillation column. The operation of the two columns being provided by means of the thermal coupling of said two columns using a thermal coupling heat exchanger.

A process for separating a mixed or raw gas feed to produce a dry gas product and a hydrocarbon liquid product is provided. The process comprises scrubbing heavier hydrocarbon components from the gas feed to produce a lighter ends gas stream and a heavier ends liquid stream; cooling the lighter ends gas stream and separating the cooled lighter ends gas stream into a cold liquid stream and the dry gas product; and using the cold liquid stream to assist in scrubbing the heavier hydrocarbon components from the gas feed.

A mixed phase pressurized unstabilized hydrocarbon stream is fed into a stabilizer column at a feed pressure. A liquid phase of stabilized hydrocarbon condensate is discharged from a bottom end of the stabilizer column, while a vapour phase of volatile components from the pressurized unstabilized hydrocarbon condensate stream is discharged from a top end of the stabilizer column. The vapour phase being discharged from the top end of the stabilizer column is compressed and subsequently passed through an ambient heat exchanger wherein partial condensation takes place. The resulting partially condensed overhead stream is separated in an overhead separator into a vapour effluent stream and an overhead liquid stream. After discharging the overhead liquid stream from the overhead separator, it is selectively divided into a liquid reflux stream and a liquid effluent stream. The liquid reflux stream is expanded to the feed pressure and fed into the stabilizer column.

A natural gas dehydration system and method includes a contactor, a flash tank, and a still interconnected by a desiccant circulation system. A reboiler is coupled to the still and the flash tank to burn the flash gas from the flash tank and heat the desiccant. A secondary burner is associated with a vent stack of the reboiler to burn the flash gas from the flash tank when not firing the reboiler.

Gas processing plants and methods are contemplated in CO.sub.2 is effectively removed to very low levels from a feed gas to an NRU unit by adding a physical solvent unit that uses waste nitrogen produced by the NRU as stripping gas to produce an ultra-lean solvent, which is then used to treat the feed gas to the NRU unit. Most preferably, the physical solvent unit includes a flash unit and stripper column to produce the ultra-lean solvent.