A system and method for removing nitrogen and producing a high pressure methane product stream and an NGL product stream from natural gas feed streams where at least 90%, and preferably at least 95%, of the ethane in the feed stream is recovered in the NGL product stream. The system and method of the invention are particularly suitable for use with feed streams in excess of 5 MMSCFD and up to 300 MMSCFD and containing around 5% to 80% nitrogen. The system and method preferably combine use of strategic heat exchange between various process streams with a high pressure rectifier tower and the ability to divert all or a portion of a nitrogen rejection unit feed stream to optionally bypass a nitrogen fractionation column to reduce capital costs and operating expenses.

An ammonia plant is disclosed, where ammonia purge gas (20), is sent to a cryogenic recovery unit, said recovery unit comprising means of cooling (102, 202, 302, 402, 502) and a high-pressure phase separator (103, 203, 303, 403, 503) operating at loop pressure; inside said unit the purge gas (20) is cooled to a cryogenic temperature, and a partial liquefaction of methane and argon is achieved; the high-pressure phase separator separates the cooled stream into a gaseous stream and a bottom liquid; the gaseous stream is reheated in a passage of a heat exchanger; the unit is then capable to export a gaseous stream (123, 223, 323, 423, 523) containing nitrogen and hydrogen at loop pressure, that can be reintroduced at the suction side of the circulator (4) of the loop.

A method and apparatus for argon recovery in which an impure argon stream is separated from air within a cryogenic air separation unit having an argon rejection column and a reflux type argon condenser disposed internally within the lower pressure column. An impure argon stream is subsequently recovered from the argon rejection column and purified within an integrated adsorbent based argon refining and purification subsystem to produce product grade argon. The waste stream from the adsorbent based argon refining and purification subsystem is recycled back to the argon rejection column so as to improve the argon recovery.

A method and apparatus for increasing argon recovery in which an impure argon stream is separated from air within a cryogenic air separation unit and purified within an integrated, multi-stage pressure swing adsorption system to produce product grade argon with high argon recovery levels.

Olefins may be recovered from a methanol to olefins reactor effluent by initially feeding the effluent to an absorber demethanizer to contact the effluent with an absorbent to recover an overheads including methane and ethylene and a bottoms including the absorbent, ethylene, and ethane. The bottoms are separated to recover an ethylene fraction and an ethane fraction. The overheads are cooled and partially condensed in a first heat exchanger to a temperature of 40 C. or greater. The resulting stream, or a portion thereof, may be further cooled and condensed via indirect heat exchange with a mixed refrigerant to a temperature of less than 40 C. The non-condensed vapors are separated from the condensed liquids to form a liquid fraction and a methane fraction. The liquid fraction is fed to the absorber demethanizer as reflux, and the methane and ethane fractions combined to form the mixed refrigerant.

A process and an apparatus are disclosed for a compact processing assembly to recover ethane, ethylene, and heavier hydrocarbon components from a hydrocarbon gas stream. The gas stream is cooled and divided into first and second streams. The first stream is further cooled, expanded to lower pressure, and supplied as a feed between two absorbing means. The second stream is expanded to lower pressure and supplied as a bottom feed to the lower absorbing means. A distillation liquid stream from the bottom of the lower absorbing means is heated in a heat and mass transfer means to strip out its volatile components. A distillation vapor stream from the top of the heat and mass transfer means is cooled by a distillation vapor stream from the top of the upper absorbing means, thereby forming a condensed stream that is supplied as a top feed to the upper absorbing means.

A process and an apparatus are disclosed for a compact processing assembly to remove carbon dioxide from a hydrocarbon gas stream. The gas stream is cooled, expanded to intermediate pressure, and fed to the top of a mass transfer means. A distillation liquid stream from the mass transfer means is heated in a first heat and mass transfer means to strip out its volatile components and form a bottom liquid product. A distillation vapor stream from the mass transfer means is combined with any vapor in the expanded cooled gas stream, and the combined vapor stream is cooled in a second heat and mass transfer means to partially condense it, forming a condensed stream that is fed to the top of the mass transfer means. A portion of the bottom liquid product is subcooled, expanded to lower pressure, and used to cool the combined vapor stream.

A process and an apparatus are disclosed for a compact processing assembly to recover ethane, ethylene, and heavier hydrocarbon components from a hydrocarbon gas stream. The gas stream is cooled and divided into first and second streams. The first stream is further cooled, expanded to lower pressure, heated, and its liquid fraction is supplied as a first top feed to an absorbing means. The second stream is expanded to lower pressure and supplied as a bottom feed to the absorbing means. A distillation vapor stream from the absorbing means is combined with the vapor fraction of the first stream, then cooled by the expanded first stream to form a condensed stream that is supplied as a second top feed to the absorbing means. A distillation liquid stream from the bottom of the absorbing means is heated in a heat and mass transfer means to strip out its volatile components.

A process and an apparatus are disclosed for a compact processing assembly to improve the recovery of C.sub.2 (or C.sub.3) and heavier hydrocarbon components from a hydrocarbon gas stream. The preferred method of separating a hydrocarbon gas stream generally includes producing at least a substantially condensed first stream and a cooled second stream, expanding both streams to lower pressure, and supplying the streams to a fractionation tower. In the process and apparatus disclosed, the expanded first stream is heated to form a vapor fraction and a liquid fraction. The vapor fraction is combined with the tower overhead vapor, directed to a heat and mass transfer means inside a processing assembly, and cooled and partially condensed by the expanded first stream to form a residual vapor stream and a condensed stream. The condensed stream is combined with the liquid fraction and supplied to the tower at its top feed point.

A process and an apparatus are disclosed for a compact processing assembly to improve the recovery of C.sub.2 (or C.sub.3) and heavier hydrocarbon components from a hydrocarbon gas stream. The preferred method of separating a hydrocarbon gas stream generally includes producing at least a substantially condensed first stream and a cooled second stream, expanding both streams to lower pressure, and supplying the streams to a fractionation tower. In the process and apparatus disclosed, the tower overhead vapor is directed to an absorbing means and a heat and mass transfer means inside a processing assembly. A portion of the outlet vapor from the processing assembly is compressed to higher pressure, cooled and substantially condensed in a heat exchange means inside the processing assembly, then expanded to lower pressure and supplied to the heat and mass transfer means to provide cooling. Condensed liquid from the absorbing means is fed to the tower.