A system and method for argon and nitrogen extraction and liquefaction from a low-pressure tail gas of an ammonia production plant is provided. The preferred tail gas of the ammonia production plant comprises methane, nitrogen, argon, and hydrogen. The disclosed system and method provides for the methane rejection via rectification and hydrogen rejection by way of a side stripper column or phase separator. The resulting nitrogen and argon containing stream is separated and liquefied in a double column distillation system.

A natural gas liquids (NGL) plant, the NGL plant comprising an absorber configured to provide an absorber overhead and an absorber bottoms, a stripper configured to produce a stripper overhead and a stripper bottoms, wherein the stripper is positioned downstream from the absorber and fluidly connected therewith such that the absorber bottoms can be introduced into the stripper, and a multi-pass heat exchanger configured to provide at least one reflux stream to the absorber, wherein the absorber and stripper are configured, in an ethane rejection arrangement, to provide the stripper overhead to a top of the absorber, and wherein the absorber and stripper are configured, in an ethane recovery arrangement, to provide the stripper overhead to a bottom of the absorber.

In an aspect, the present disclosure provides a method for the oxidative coupling of methane to generate hydrocarbon compounds containing at least two carbon atoms (C.sub.2+ compounds). The method can include mixing a first gas stream comprising methane with a second gas stream comprising oxygen to form a third gas stream comprising methane and oxygen and performing an oxidative coupling of methane (OCM) reaction using the third gas stream to produce a product stream comprising one or more C.sub.2+ compounds.

Implementations described and claimed herein provide systems and methods for processing liquefied natural gas (LNG). In one implementation, a dry feed gas is received. The dry feed gas is chilled with clean vapor from a heavies removal column to form a chilled feed gas. The chilled feed gas is partially condensed into a vapor phase and a liquid phase. The liquid phase retains freezing components. The freezing components are extracted using a reflux stream in the heavies removal column. The freezing components are removed as a condensate. The vapor phase is compressed into a clean feed gas. The clean feed gas is free of the freezing components for downstream liquefaction.

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 expanded to tower pressure and supplied to the tower at an upper mid-column feed position. A distillation vapor stream is withdrawn from the fractionation tower below the mid-column feed position and is heated, compressed to higher pressure, and cooled to substantial condensation before it is expanded and supplied to the tower as its top feed.

A process and an apparatus are disclosed for separation of a hydrocarbon gas stream containing methane and heavier hydrocarbons and significant quantities of nitrogen and carbon dioxide. The gas stream is cooled and expanded, then fractionated in a first distillation column into a first overhead vapor and a hydrocarbon liquid stream containing the majority of the carbon dioxide. The hydrocarbon liquid stream is fractionated into a hydrocarbon vapor stream and a less volatile fraction comprised of heavier hydrocarbons.

The first overhead vapor is cooled, expanded, and separated into vapor and liquid streams. Both streams are cooled and expanded before feeding a second distillation column that produces a second overhead vapor that is predominantly nitrogen and a bottom liquid that is predominantly methane. The bottom liquid is vaporized and combined with the hydrocarbon vapor stream to form a volatile residue gas fraction containing the majority of the methane.

A method includes: recovering and compressing a head stream coming from a separation column, to form a stream of compressed purified natural gas; liquefying the stream of compressed purified natural gas in a liquefaction unit to form a stream of a pressurized liquefied natural gas; flash expanding of the stream of pressurized liquefied natural gas and recovering in a storage; recovering and compressing of a flow of flash gas coming from the expanding; separating the flow of compressed flash gas (132) into a fuel stream and a recycle stream; cooling and expanding the recycle stream, then introducing the cooled and expanded recycle stream at a head stage of the separation column.

A process for liquefying a natural gas feed stream including cooling a feed gas stream to obtain a liquefied natural gas stream; introducing the liquefied natural gas stream into a deazotization column to produce a liquefied natural gas stream and a nitrogen-enriched vapor stream; at least partially condensing at least part of the nitrogen-enriched vapor stream to produce a two-phase stream; introducing the two-phase stream into a phase-separating vessel to produce a first liquid stream and a first nitrogen-enriched gas stream; introducing at least part of the nitrogen-enriched gas stream into a distillation column thereby producing a second nitrogen-enriched stream containing less than 1 mol % of methane and a second liquid stream containing less than 10 mol % of nitrogen; wherein at least part of the liquefied natural gas stream is used to cool the at least part of the nitrogen-enriched vapor stream in said heat exchanger.

A method and apparatus for producing liquefied natural gas (LNG) from a natural gas stream. Heavy hydrocarbons are removed from the natural gas stream in a separator to generate a bottom stream and a separated natural gas stream, which is used as a coolant in a heat exchanger to generate a pretreated natural gas stream. The pretreated natural gas stream is compressed and cooled to form a chilled pretreated natural gas stream, part of which forms a recycle stream to exchange heat with the separated natural gas stream in the heat exchanger, thereby generating a cooled recycle stream. The temperature and pressure of the cooled recycle stream are reduced. The cooled recycle stream is then separated into an overhead stream and a reflux stream, which is directed to the separator. The chilled pretreated gas stream is liquefied to form LNG.

The present invention is directed to a method and system of separating carbon monoxide from syngas mixtures with low methane content by cryogenic means where a partial condensation cycle is generally employed, and more specifically towards providing a methane slip stream to the feed in order to reduce the potential for any carbon dioxide entering the cold box to freeze, thereby preventing plugging of the cold box heat exchanger.