Methods and systems for recovering alkenes (e.g. ethylene, propylene) from process gas streams, including multi-step condensing of the process gas stream, are provided herein.

Methods and systems for recovering nitrogen and alkenes (e.g. ethylene, propylene) from process gas streams, including multi-step condensing of the process gas stream, are provided herein.

Methods and systems for recovering alkenes (e.g. ethylene, propylene) and nitrogen from process gas streams, including multi-step condensing of the process gas stream, are provided herein.

Methods and systems for recovering alkene (e.g., C.sub.2-C.sub.4 alkene) gas as well as producing pressurized alkene (e.g., C.sub.2-C.sub.4 alkene) gas from process gas streams including lower concentrations of alkenes are provided herein.

A main heat exchanger receives and partially condenses an effluent fluid stream so that a mixed phase effluent stream is formed. A primary separation device receives and separates the mixed phase effluent stream into a primary vapor stream including hydrogen and a primary liquid stream including an olefinic hydrocarbon. The main heat exchanger receives and warms at least a portion of the primary vapor stream to provide refrigeration for partially condensing the effluent fluid stream. The main heat exchanger also receives, warms and partially vaporizes the primary liquid stream. A mixed refrigerant compression system also provides refrigeration in the main heat exchanger.

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.

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 gas recovery system separates a mixed gas including a process gas and an inert gas. The gas recovery system includes a cooling section for cooling and liquefying the process gas contained in the mixed gas by cooling the mixed gas at a temperature higher than a condensation temperature of the inert gas and lower than a condensation temperature of the process gas, a separating section for separating the cooled mixed gas into the process gas in a liquid state and the inert gas in a gas state, and a process gas recovery line that is connected to the separating section which circulates and gasifies the liquid-state process gas and then supplies the process gas into the a compressor. The mixed gas is formed by mixing the process gas, which is compressed by the compressor, and the inert gas, which is supplied to a seal portion of the compressor.

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 method for removing condensable components from a fluid containing condensable components. The method involves optimizing the temperature of an initial feed stream including the condensable components through heat exchange and cooling to condense liquids there from. The liquids are removed to form a gas stream which is then compressed and after-cooled to form a high pressure stream. A portion of the high pressure stream is expanded to form a cooled low pressure stream which is mixed with the initial feed stream to augment cooling and condensation of condensable components in the initial feed stream.