A method for separating nitrogen from an inlet gas having less than 25 mole % nitrogen includes supplying the inlet gas having less than 25 mole % nitrogen to a nitrogen separation system configured with cryogenic refrigeration.

A system and method for removing nitrogen from natural gas using two fractionating columns, that may be stacked, and a plurality of separators and heat exchangers, with horsepower requirements that are 50-80% of requirements for prior art systems. The fractionating columns operate at different pressures. A feed stream is separated with a vapor portion feeding the first column to produce a first column bottoms stream that is split into multiple portions at different pressures and first column overhead stream that is cooled and separated into vapor and liquid portions to control subcooling of the vapor portion prior to feeding the second column. Heat exchange between first column and second column streams provides first column reflux and reboil heat for a second column ascending vapor stream. Three sales gas streams are produced, each at a different pressure.

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.

Methods and systems for producing a product natural gas employing a natural gas liquids (NGL) recovery unit followed by removing nitrogen in a nitrogen rejection unit (NRU) operatively connected with the NGL recovery unit by a pressure management sub-system (PMSS). In one embodiment, the PMSS includes a first conduit fluidly connecting the top of a demethanizer column (or an existing conduit connected to the top of the demethanizer) to a separator, a second conduit fluidly connecting the separator to a pump, the pump connected to a distillation column in the NRU by a third conduit, in another embodiment, the PMSS includes a first conduit fluidly connecting an NGL expander to a separator, allowing natural gas vapors and nitrogen to be fed to the NRU column through a second conduit. Alternatively, the PMSS allows mixture from the NGL recovery unit expander to be fed directly via the first conduit to the NRU distillation column.

A system and method for producing an NGL product stream in either an ethane retention or rejection mode. Rejection modes include (a) two heat exchange stages between a feed stream and first separator bottoms stream and cooling a side stream withdrawn from a fractionation tower through heat exchange with both the fractionation tower and second separator overhead streams; or (b) warming the first separator bottoms stream and fractionation overhead stream through heat exchange with the side stream prior to heat exchange with the feed stream, to achieve 4-15% ethane recovery and 97%+ propane recovery. In ethane retention mode, a portion of the feed stream and portions of a first separator overhead and bottoms streams are 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 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 method for loading liquefied nitrogen (LIN) into a cryogenic storage tank initially containing liquid natural gas (LNG) and a vapor space above the LNG. First and second nitrogen gas streams are provided. The first nitrogen stream has a lower temperature than the second nitrogen gas stream. While the LNG is offloaded from the storage tank, the first nitrogen gas stream is injected into the vapor space. The storage tank is then purged by injecting the second nitrogen gas stream into the storage tank to thereby reduce a natural gas content of the vapor space to less than 5 mol %. After purging the storage tank, the storage tank is loaded with LIN.

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.

Methods and systems for cryogenically separating contaminants and regasification of LNG utilizing common refrigeration equipment and/or fuel. An integrated system includes: a component for separating contaminants from an input feed stream; a heat exchanger coupled to a first line, wherein: the first line is coupled to the component for separating contaminants, and the heat exchanger cools a first feed stream of the first line; and a LNG regasification system comprising a vaporizer, wherein: the vaporizer heats a LNG stream of the LNG regasification system, and the heat exchanger functions as the vaporizer. A process includes: separating contaminants from an input feed stream with a component for separating contaminants; cooling a first feed stream with a heat exchanger, wherein the heat exchanger is coupled to the component for separating contaminants; and heating a LNG stream with a vaporizer of a LNG regasification system, wherein the heat exchanger functions as the vaporizer.

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.