One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing an integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

In a helium purification process, a stream containing at least 10% of helium, at least 10% of nitrogen in addition to hydrogen and methane is separated to form a helium-enriched stream containing hydrogen, a first stream enriched in nitrogen and in methane and a second stream enriched in nitrogen and in methane, the helium-enriched stream is treated to produce a helium-rich product and a residual gas containing water, the residual gas is treated by adsorption (TSA) to remove the water and the regeneration gas from the adsorption is sent to a combustion unit (O).

The method includes cooling and liquefying a feed gas stream, separating a stream obtained from the feed gas stream, and recovering a treated gas stream and a natural gas liquid stream. The method further includes compressing the treated gas stream in order to form a compressed treated gas stream, and fractionating the natural gas liquid stream into a plurality of hydrocarbon fractions (28, 30, 32, 33). The method additionally includes withdrawing from the compressed treated gas stream, of a recycle stream, and reintroducing the recycle stream without cooling into the feed gas stream, into the cooled feed gas stream, or into a stream obtained from the cooled feed gas stream upstream of an expander.

A natural gas liquefaction method and system having integrated nitrogen removal. Recycled LNG gas is cooled in a separate and parallel circuit from the natural gas stream in the main heat exchanger. Cooled recycled gas and natural gas streams are directed to a nitrogen rectifier column after the warm bundle. The recycle stream is introduced to the rectifier column above the natural gas stream and at least one separation stage is located in the rectifier column between the recycle stream inlet and the natural gas inlet. The bottom stream from the rectifier column is directed to a cold bundle of the main heat exchanger where it is subcooled.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing an integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing a integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

A process for liquefying hydrogen gas including the following is disclosed: cooling the hydrogen gas to an intermediate temperature by heat exchange with a refrigerant circulating in a refrigeration loop provided with a higher temperature expander and a lower temperature expander, wherein the outlet stream from the lower temperature expander contains some condensed refrigerant; a means is provided of separating the condensate from the circulating refrigerant; and further cooling of the hydrogen gas by heat exchange with evaporation and reheating of the said condensate.

The fluid in the refrigeration loop is typically methane (such as natural gas after removal of carbon dioxide, water vapor and other impurities), or nitrogen, or a mixture thereof.

A process for producing hydrocarbons includes providing a component mixture containing hydrocarbons and a feed mixture containing hydrocarbons having two or more carbon atoms and lower boiling compounds using a portion of the component mixture, and forming a heavy fraction and a light fraction using the feed mixture. The heavy fraction contains a portion of the hydrocarbons from the feed mixture and is at least poor in the lower boiling components. The light fraction contains a portion of the lower boiling components from the feed mixture and is at least poor in the hydrocarbons from the feed mixture. The heavy fraction and a first intermediate fraction are formed using some of the feed mixture in low-temperature separation. Some of the first intermediate fraction is subjected to non-cryogenic separation while obtaining the light fraction and a second intermediate fraction. A portion of the second intermediate fraction is recycled to the process.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing an integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.

An energy efficient process for NGL recovery and production of compressed natural gas (CNG) in which natural gas is fed to a first gas separation membrane-based separation stage where it is separated into a permeate and a retentate. The high C.sub.3+ concentration first stage permeate is chilled and separated to provide liquid phase NGL and a gaseous phase. The first stage retentate is separated at a second gas membrane-based separation stage to produce a retentate meeting pipeline specifications for CNG (including hydrocarbon dewpoint) and a permeate that is recycled to the first stage. The gaseous phase, constituting a low BTU fuel, may be used in on-site power generation equipment and/or in internal combustion engines. The second stage permeate (and optionally the third stage retentate) is (are) recycled back to the first stage to enhance the production of NGL and CNG. The gaseous phase may instead be fed to a third stage to produce a third permeate and a third residue, in which case the third permeate is recycled to the first stage and the third retentate is a low BTU fuel which may be used in on-site power generation equipment and/or in internal combustion engines.