A system and method for processing an NGL product stream from a natural gas feed stream in either an ethane retention or ethane rejection mode utilizing heat exchange of particular process streams. In ethane rejection mode, there are preferably two stages of heat exchange between the feed stream and a first separator bottoms stream and a side stream withdrawn from a fractionation tower is cooled through heat exchange with both the fractionation tower and second separator overhead streams, and optionally with an external refrigerant, resulting in 5-15% ethane and at least 97% propane recovery. In ethane retention mode, a portion of the feed stream and portions of a first separator overhead and bottoms streams are preferably separately cooled through heat exchange with other process streams, including the entireties of a recycled residue gas and fractionation column overhead streams, resulting in around 99% ethane and around 100% propane recovery.

A moderate pressure, argon and nitrogen producing cryogenic air separation unit and air separation cycle having a higher pressure column, a lower pressure column and an argon column arrangement is disclosed. The moderate pressure, argon and nitrogen producing cryogenic air separation unit is configured to take a first portion of an oxygen enriched stream from the lower pressure column, which together with an external source of liquid nitrogen is used as the boiling side refrigerant to condense the argon in the argon condenser. Use of the external source of liquid nitrogen in the argon condenser allows a second portion of the oxygen enriched stream from the lower pressure column to be taken as a liquid oxygen product stream.

A method for obtaining an air product in an air separating system in which a liquid fraction is obtained from feed air and used to provide the air product and in which the liquid fraction is temporarily stored in a tank arrangement. A tank arrangement with at least two tanks is used, and the liquid fraction is fed to at least one of the tanks and/or is removed from at least one of the tanks in order to provide the air product. In the process, the liquid fraction is not fed to and removed from any one of the tanks at the same time, and the composition of the liquid fraction in a tank is ascertained prior to each removal of the liquid fraction from the tank. An air separating system is also described.

A cryogenic distillation tower for separating a feed stream. The tower includes a distillation section. A controlled freeze zone section is situated above the distillation section and forms a solid from the feed stream. The controlled freeze zone section includes a spray assembly in an upper section and a melt tray assembly in a lower section. The melt tray assembly includes at least one vapor stream riser that directs the vapor from the distillation section into liquid retained by the melt tray assembly, and one or more draw-off openings positioned to permit a portion of the liquid to exit the controlled freeze zone section. The portion of the liquid indirectly exchanges heat with a heating fluid. One or more return inlets return the portion of the liquid to the melt tray assembly after it has been heated in the heat exchanger.

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 apparatus and process for the compression, expansion, evaporation, and liquefaction of gases or gaseous mixtures consisting of a gas liquefaction column comprising successive chambers made of balloons resembling those used in pneumatic suspensions, and double-piston bases in between the upper and lower end of each chamber. Some of the double-piston bases are fixed while others in between are mobile. The group of mobile double-piston bases is activated in a linear to-and-fro vertical stroke while the other group of double-piston bases remains stationary. This results in consecutive suction and compression of the chambers, creating a Joule-Thomson effect at each of them. This results in the cooling and liquefaction of the gas or gaseous mixture. The apparatus also comprises humidity extractors, and different types of valves and piping.

A moderate pressure nitrogen and argon producing cryogenic air separation unit is provided that includes a three distillation column system and turbine air stream bypass arrangement or circuit. The turbine air stream bypass arrangement or circuit is configured to improve argon and nitrogen recoveries in select operating modes by optionally diverting a portion of the turbine air stream to a nitrogen waste stream circuit drawn from the lower pressure column of the cryogenic air separation unit such that the diverted portion of the turbine air stream bypasses the distillation column system.

The method for reducing or removing non-volatile impurities in a high-purity oxygen liquid comprises: an oxygen vaporization step for vaporizing a high-purity oxygen liquid obtained from a high-purity oxygen rectification column in an air separation unit for producing the high-purity oxygen liquid; and an oxygen recondensing step for recondensing oxygen gas vaporized in the oxygen vaporization step. This method may also comprise a high-purity oxygen liquid extraction step for extracting a condensate obtained in the oxygen recondensing step.

A system for conditioning a sour gas feed stream for a cryogenic distillation tower. A dehydration unit separates the sour gas feed stream into a first stream including water and a feed stream. A sequential cooling assembly is coupled to both the dehydration unit and the cryogenic distillation tower. The sequential cooling assembly includes: a first stage that separates the feed stream into a partially cooled feed stream and a second stream including acid gas; a second stage that cools the partially cooled feed stream into a cooled feed stream and a third stream including acid gas; and a cooled feed stream header coupled to a cryogenic distillation tower feed inlet. The first stage, the second stage, or both send at least one of the second and third streams to a bottom section of the cryogenic distillation tower.

A method and apparatus for producing compressed nitrogen and liquid nitrogen. A separation system has a high-pressure column, a low-pressure column with a top condenser and a main condenser. Air is compressed in an air compressor, purified, cooled in a heat exchanger and introduced into the high-pressure column. A first part of the gaseous top nitrogen from the low-pressure column becomes compressed nitrogen product. A second part of the gaseous top nitrogen is condensed in the condensing space of the top condenser and vapor is drawn off as a residual gas stream. The vapor is expanded in a first expansion machine. A second compressed nitrogen stream from the top of the high-pressure column is expanded in a second expansion machine and then drawn off as compressed nitrogen product. A part of the nitrogen condensed in the top condenser is drawn off as liquid nitrogen product.