A method for improving the capacity of an existing air separation unit employing a lost air turbine is provided in which the capacity is increased by operating the existing air separation unit as previously operated, with the exception of collecting the lost air from the lost air turbine, and instead of venting said lost air to the atmosphere, the lost air is compressed in a supplemental air compressor and returned to the air separation unit at a location downstream a front-end purification unit and upstream a booster. This setup advantageously allows for increased production without having to adjust the sizing of the front-end purification unit or main air compressor.

Impurities that are less volatile than carbon dioxide, e.g. hydrogen sulfide, are removed from crude carbon dioxide by processes involving distillation of said crude carbon dioxide in a distillation column system operating at super-atmospheric pressure(s) to produce carbon dioxide-enriched overhead vapor and bottoms liquid enriched with said impurities. Where such processes involve a single heat pump cycle, significant savings in power consumption are realized when the distillation column system is re-boiled by at least partially vaporizing liquid in or taken from an intermediate location in the column system.

An apparatus for the distillation of air by cryogenic distillation is provided. The apparatus can include an enclosure; a first distillation column configured to operate at a first pressure; a second distillation column configured to operate at a second pressure that is lower than the first pressure, the second distillation column being placed above the first distillation column and forming therewith a double column; a subcooling heat exchanger configured to cool at least one liquid from the first distillation column upstream of the second distillation column and configured to warm a gaseous nitrogen stream from the second distillation column; and an argon column configured to separate an argon enriched stream from the second distillation column and configured to produce an argon rich stream. In certain embodiments, the first distillation column, the second distillation column, the argon column and the subcooling heat exchanger are disposed within the enclosure, and/or the subcooling heat exchanger is disposed directly underneath the first distillation column or the argon column.

The invention relates to a method for the treatment of natural gas containing carbon dioxide, methane and paraffins. The method comprising: a step of extracting the paraffins from the natural gas in a paraffin-removal column, and a step of separating the carbon dioxide and the methane in a distillation column. The operation of the two columns being provided by means of the thermal coupling of said two columns using a thermal coupling heat exchanger.

An overhead recycle process apparatus (100) comprises a heat exchange arrangement (116, 118, 120, 146, 150, 198) and a separator (110) in fluid communication with an absorber (104) and a de-ethaniser (106), the absorber (104) having a reflux inlet port (164). An ethane rectifier (170) in fluid communication with the de-ethaniser (106) is also provided, the de-ethaniser (106) being arranged to provide cooling by heat exchange to an overhead stream path (194) of the ethane rectifier (170). The ethane rectifier (170) comprises a reflux drum (182) having an ethane outlet port (184) and a vapour phase outlet port (185) in fluid communication with the reflux inlet port (164) of the absorber (104).

A system for removing freezing components from a feed gas includes a heavy hydrocarbon removal heat exchanger and a scrub device. The scrub device includes a scrub column that receives a cooled feed gas stream from the heat exchanger and a reflux separation device. Vapor from the scrub column is directed to the heat exchanger and cooled to create a reflux stream that includes a liquid component. This reflux stream is directed to the reflux separation device and a resulting liquid component stream is used to reflux the column. Vapor from the reflux separation device is expanded and directed to the heat exchanger, where it provides refrigeration, and a processed feed gas line.

The present invention relates to a method of cooling and separating a hydrocarbon stream: (a) passing an hydrocarbon feed stream (7) through a first cooling and separation stage to provide a methane enriched vapour overhead stream (110) and a methane depleted liquid stream (10); (b) passing the methane depleted liquid stream (10) to a fractionation column (200) to obtain a bottom condensate stream (210), a top stream enriched in C1-C2 (220) and a midstream enriched in C3-C4 (230), (c) cooling the upper part of the fractionation column (201) by a condenser (206), (d) obtaining a split stream (112) from the methane enriched vapour overhead stream (110) and obtaining a cooled split stream (112) by expansion-cooling the split stream (112), (e) providing cooling duty to the top of the fractionation column (201) using the cooled split stream (112).

A method and apparatus for cooling a hydrocarbon stream such as natural gas. An initial hydrocarbon stream is passed through a first separator to provide an initial overhead stream and a mixed hydrocarbon feed stream. The initial overhead stream is cooled to provide a cooled hydrocarbon stream such as LNG, and at least a C1 overhead stream and one or more C2, C3 and C4 overhead streams are separated from the mixed hydrocarbon feed stream. At least a fraction of at least one of the group comprising: the C2 overhead stream, the C3 overhead stream and the C4 overhead stream is cooled with the C1 overhead stream to provide a cooled stream, which is further cooled against at least a fraction of the cooled, preferably liquefied, hydrocarbon stream to provide an at least partly liquefied cooled stream.

A process for separating a mixed or raw gas feed to produce a dry gas product and a hydrocarbon liquid product is provided. The process comprises scrubbing heavier hydrocarbon components from the gas feed to produce a lighter ends gas stream and a heavier ends liquid stream; cooling the lighter ends gas stream and separating the cooled lighter ends gas stream into a cold liquid stream and the dry gas product; and using the cold liquid stream to assist in scrubbing the heavier hydrocarbon components from the gas feed.

A method of obtaining a liquefied hydrocarbon-rich fraction (product fraction) having a nitrogen content of 1 mol %, wherein the hydrocarbon-rich fraction is liquefied and subcooled with a refrigeration circuit and then subjected to a rectificative removal of nitrogen is disclosed.