A system and method for argon and nitrogen extraction from a feed stream comprising hydrogen, methane, nitrogen and argon, such as tail gas of an ammonia production plant is provided. The disclosed system and method provides for nitrogen-argon rectification and the methane rejection within a column system comprised of at least one distillation column. Nitrogen and argon are further separated and to produce liquid products. An argon stripping column arrangement is disclosed where residual argon is further removed from the methane-rich fuel gas and recycled back to the feed stream.

Integrated systems are provided for the production of higher hydrocarbon compositions, for example liquid hydrocarbon compositions, from methane using an oxidative coupling of methane system to convert methane to ethylene, followed by conversion of ethylene to selectable higher hydrocarbon products. Integrated systems and processes are provided that process methane through to these higher hydrocarbon products.

This method comprises cooling the feed natural gas in a first heat exchanger and introducing the cooled, feed natural gas into a first separation flask. It comprises the dynamic expansion of a turbine supply flow in a first expansion turbine and introducing the expanded flow into a separation column. This method comprises removing, at the head of the separation column, a head flow rich in methane and removing a first recirculation flow from the compressed head flow rich in methane. The method comprises forming at least a second recirculation flow obtained from the head flow rich in methane downstream of the separation column and forming a dynamic expansion flow from the second recirculation flow.

The present disclosure provides oxidative coupling of methane (OCM) systems for small scale and world scale production of olefins. An OCM system may comprise an OCM subsystem that generates a product stream comprising C.sub.2+ compounds and non-C.sub.2+ impurities from methane and an oxidizing agent. At least one separations subsystem downstream of, and fluidically coupled to, the OCM subsystem can be used to separate the non-C.sub.2+ impurities from the C.sub.2+ compounds. A methanation subsystem downstream and fluidically coupled to the OCM subsystem can be used to react H.sub.2 with CO and/or CO.sub.2 in the non-C.sub.2+ impurities to generate methane, which can be recycled to the OCM subsystem. The OCM system can be integrated in a non-OCM system, such as a natural gas liquids system or an existing ethylene cracker.

Enhancements to a dual column, nitrogen producing cryogenic air separation unit with waste expansion are provided. Such enhancements include an improved air separation cycle that uses: (i) three condenser-reboilers; (ii) a reverse reflux stream from the condenser-reboiler associated with the lower pressure column to the higher pressure column; and (iii) a recycle stream of a portion of the vapor from one or more of the condenser-reboilers that is recycled back to the incoming feed stream and or the compressed purified air streams to yield improvements in the performance of such dual column, nitrogen producing cryogenic air separation units in terms of overall nitrogen recovery as well as power consumption compared to conventional dual column, nitrogen producing cryogenic air separation units employing waste expansion.

In a method for separating a mixture containing carbon dioxide, the mixture is cooled in a heat exchanger and partially condensed and a first liquid is separated from the mixture in a first system operating at low temperature comprising at least one first phase separator and a gas from the first system is treated in a membrane system to produce a permeate and a non-permeate, the gas from the first system being divided into two portions, a first portion being sent to the membrane system without being heated and a second portion being heated to at least an intermediate temperature of the heat exchanger and then sent to the membrane system without being cooled.

A method and apparatus for producing a high-pressure gas from an air separation unit is provided, in which the method includes the steps of introducing a cold air feed into a distillation column system under conditions effective for separating the cold air feed into a first air gas and a second air gas; withdrawing the first and second air gases from the distillation column system and warming said first and second air gases in a main heat exchanger, wherein the first air gas is withdrawn from the distillation column system at a medium pressure; splitting the first air gas into a first fraction and a second fraction; expanding the first fraction in a turbine; and compressing the second fraction in a booster to a pressure that is higher than the medium pressure, wherein the booster is powered by the turbine

A method and apparatus for liquefying a feed gas stream comprising natural gas and carbon dioxide. A method includes compressing an input fluid stream to generate a first intermediary fluid stream; cooling the first intermediary fluid stream with a first heat exchanger to generate a second intermediary fluid stream, wherein a temperature of the second intermediary fluid stream is higher than a carbon dioxide-freezing temperature for the second intermediary fluid stream; expanding the second intermediary fluid stream to generate a third intermediary fluid stream, wherein the third intermediary fluid stream comprises solid carbon dioxide; separating the third intermediary fluid stream into a fourth intermediary fluid stream and an output fluid stream, wherein the output fluid stream comprises a liquefied natural gas (LNG) liquid; and utilizing the fourth intermediary fluid stream as a cooling fluid stream for the first heat exchanger.

An expander and motor-compressor unit is disclosed. The unit includes a casing and an electric motor arranged in the casing. A compressor is arranged in the casing and drivingly coupled to the electric motor through a central shaft. Furthermore, a turbo-expander is arranged for rotation in the casing and is drivingly coupled to the electric motor and to the compressor through the central shaft.

A method to pre-treat an inlet natural gas stream at gas pressure reduction stations to produce LNG removes water and carbon dioxide from a natural gas stream. The energy required for the process is provided by recovering pressure energy in the inlet gas stream. The process eliminates the conventional gas pre-heating process at pressure reductions stations employing gas combustion heaters. The process provides a method to produce LNG at natural gas pressure reduction that meets product specifications.