A system used to recycle exhaust gas during olefin polymer production, comprising: a compression cooling mechanism (101); a hydrocarbon membrane separation mechanism (102) and a hydrogen membrane separation mechanism (103), both connected to a first outlet (202) of the compression cooling mechanism; and a deep cooling mechanism (104) connected to a first outlet (208) of the hydrogen membrane separation mechanism. A method used to recycle exhaust gas during olefin polymer production, comprising a compression cooling step, a hydrocarbon membrane separation step, a hydrogen membrane separation step and a deep cooling step.

A process and an apparatus are disclosed for the recovery of components from a hydrocarbon gas stream containing significant quantities of components more volatile than methane (hydrogen, nitrogen, etc.). The gas stream is partially condensed, then the remaining vapor is expanded to lower pressure and supplied to a fractionation tower at a mid-column feed position. The condensed liquid is cooled and divided into two portions. The first portion is expanded to tower pressure, heated by cooling the liquid, and supplied to the tower at a lower column feed position. The second portion is further cooled, expanded to tower pressure, and supplied to the tower at a top feed position. The tower overhead vapor is heated by cooling the second portion. The quantities and temperatures of the feeds to the tower maintain the overhead temperature of the tower whereby the major portion of the desired components is recovered.

A process for removing a foulant from a gas stream. The gas stream is cooled in a series of heat exchangers, causing a portion of the foulant to desublimate and become entrained in a cryogenic liquid. This foulant slurry stream is pressurized, cooled, and separated into a pressurized foulant solid stream and the cryogenic liquid stream. The pressurized foulant solid stream is melted to produce a liquid foulant stream. Heat exchange processes, both internal and external, are provided that close the heat balance of the process. In this manner, the foulant is removed from the gas stream.

The present invention provides a method of liquefying a contaminated hydrocarbon-containing gas stream: (a) providing a CO2 contaminated hydrocarbon-containing gas stream (20); (b) cooling the contaminated hydrocarbon-containing gas stream to obtain a partially liquefied stream (70); (c) separating the partially liquefied stream obtaining a liquid stream (90); (d) cooling the liquid stream (90) in a direct contact heat exchanger (200) obtaining a multiphase stream (201) containing at least a liquid phase and a solid CO2 phase; (e) separating the multiphase stream in a solid-liquid separator (202) obtaining a CO2 depleted liquid stream (141); (f) passing the CO2 depleted liquid stream (141) to a further cooling, pressure reduction and separation stage to generate a further CO2 enriched slurry stream (206); (g) passing at least part of the further CO2 enriched slurry stream (206) to the direct contact heat exchanger (200) to provide cooling duty to and mix with the liquid stream (90).

Implementations described and claimed herein provide systems and methods for processing liquefied natural gas (LNG). In one implementation, a feed gas is received and partially condensed into a two-phase stream by expanding the feed gas. A liquid containing fouling components is removed from the two-phase stream. A vapor generated from the two-phase stream is compressed into a compressed feed gas. The compressed feed gas is directed into a feed chiller heat exchanger. The compressed feed gas is free of the fouling components.

Various embodiments include an apparatus for liquefying gas comprising: an inlet for a pressurized gas; a countercurrent heat exchanger with a first channel for the pressurized gas to flow in a first direction; an expansion nozzle, such that the pressurized gas flows from the first channel into the nozzle, and flows out to form an aerosol comprising a gaseous phase and liquid droplets; an aerosol breaker separating at least some of the droplets out of the gaseous phase; a collecting region for gathering and collecting droplets dripping off the aerosol breaker; and a second channel of the countercurrent heat exchanger surrounding the first channel. The flow of the gaseous phase out of the expansion nozzle is colder compared to the gas flowing through the second channel in a second direction opposite to the first direction. The second channel surrounds the first channel. The apparatus comprises a monolithic structure.

Methods and systems for separating components are disclosed. A process liquid stream is provided that contains a first component and a second component. The process liquid stream is cooled to near a temperature at which the second component forms a solid. The process liquid stream is expanded into a vessel such that the first component and a first portion of the second component vaporize to form a process vapor stream and a second portion of the second component forms a solid to form a solid product stream. The process vapor stream and the solid product stream are passed out of the vessel.

A system and method for cooling a gas using a mixed refrigerant includes a compressor system and a heat exchange system, where the compressor system may include an interstage separation device or drum with no liquid outlet, a liquid outlet in fluid communication with a pump that pumps liquid forward to a high pressure separation device or a liquid outlet through which liquid flows to the heat exchanger to be subcooled. In the last situation, the subcooled liquid is expanded and combined with an expanded cold temperature stream, which is a cooled and expanded stream from the vapor side of a cold vapor separation device, and subcooled and expanded streams from liquid sides of the high pressure separation device and the cold vapor separation device, or combined with a stream formed from the subcooled streams from the liquid sides of the high pressure separation device and the cold vapor separation device after mixing and expansion, to form a primary refrigeration stream.

A system and method for cooling a gas using a mixed refrigerant includes a compressor system and a heat exchange system, where the compressor system may include an interstage separation device or drum with no liquid outlet, a liquid outlet in fluid communication with a pump that pumps liquid forward to a high pressure separation device or a liquid outlet through which liquid flows to the heat exchanger to be subcooled. In the last situation, the subcooled liquid is expanded and combined with an expanded cold temperature stream, which is a cooled and expanded stream from the vapor side of a cold vapor separation device, and subcooled and expanded streams from liquid sides of the high pressure separation device and the cold vapor separation device, or combined with a stream formed from the subcooled streams from the liquid sides of the high pressure separation device and the cold vapor separation device after mixing and expansion, to form a primary refrigeration stream.

A method of liquefying natural gas. The method comprises cooling a gaseous natural gas process stream with a refrigerant flowing in a path isolated from the natural gas process stream. The refrigerant may differ in composition from a composition of the natural gas process stream, and the refrigerant composition may be selected to enhance efficiency of the refrigerant path with regard to a specific composition of the natural gas process stream. The refrigeration path may be operated at pressures, temperatures and flow rates differing from those of the natural gas process stream. Other methods of liquefying natural gas are described. A natural gas liquefaction plant is also described.