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 split or separated into two portions at least one of which is subcooled prior to feeding the top of the second column. Optional 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.

In a process for the combined production of a) a hydrogen-enriched gas and a carbon monoxide-enriched gas and/or b) a mixture of hydrogen and carbon monoxide by cryogenic distillation and scrubbing, a still liquor is extracted from a scrubbing column and sent to a stripping column, a still liquor is extracted from the stripping column and sent to a separating column for carbon monoxide and methane and a cooling fluid is used at a pressure greater than that of the head of the separating column for cooling at least one fluid extracted at an intermediate level from the scrubbing column.

A process for recovering at least one fluid (e.g. argon gas and/or nitrogen gas, etc.) from a feed gas (e.g. air) can include utilization of a compression system, primary heat exchanger unit, plant processing units to separate and recover at least one desired fluid (e.g. nitrogen gas, argon gas, etc.). In some embodiments, the process can be configured so that fluid flows output from a low pressure column and/or high pressure column of the plant can provide a condensation duty or refrigeration duty that is utilized to process certain fluid flows for recovery of argon and/or nitrogen gases. Some embodiments can be configured to provide an improved recovery of argon and/or nitrogen as well as an improvement in operational efficiency by reducing an amount of power (e.g. electrical power) needed to recover the nitrogen and/or argon.

The invention relates to a process for cryogenic fractionation of air using an air fractionation plant comprising a rectification column system comprising a high-pressure column operated at a pressure level of 9 to 14.5 bar, a low-pressure column operated at a pressure level of 2 to 5 bar, and an argon column. It is envisaged that a recirculating stream is formed using the second tops gas or a portion thereof, which is heated, compressed, cooled again, and after partial or complete liquefaction or in the unliquefied state is introduced partially or completely, or in fractions, into the first rectification column and/or into the second rectification column. The present invention also relates to a corresponding system.

A method and device to produce oxygen by the low-temperature separation of air at variable energy consumption. A distillation column system comprises a high-pressure column, a low-pressure column and a main condenser, a secondary condenser and a supplementary condenser. Gaseous nitrogen from the high-pressure column is liquefied in the main condenser in indirect heat exchange with an intermediate liquid from the low-pressure column. A first liquid oxygen stream from the bottom of the low-pressure column is evaporated in the secondary condenser in indirect heat exchange with feed air to obtain a gaseous oxygen product. The supplementary condenser serves as a bottom heating device for the low-pressure column and is heated by means of a first nitrogen stream from the distillation column system, which nitrogen stream was compressed previously in a cold compressor.

A compressed air stream is cooled in an exchanger to form a compressed cooled air stream. The stream is then cryogenically compressed in a first compressor to form a first pressurized gas stream. The first pressurized gas stream is further cooled in the exchanger, cryogenically compressed in a second compressor, and then it is cooled and partially liquefied. The cooled and partially liquefied product is then fed to a system of distillation columns. A liquid product is removed from the system of distillation columns. This product is then pressurized, vaporized and warmed in the exchanger to yield pressurized gaseous product.

A system and method for argon and nitrogen extraction from a feed stream comprising hydrogen, methane, nitrogen and argon, such as a low-pressure tail gas of an ammonia production plant is provided. The disclosed system and method provides for a rectification system wherein an argon depleted gaseous stream and a methane rich liquid stream are produced and subsequently combined in whole or in part prior to vaporization. Nitrogen and argon containing streams may also be produced from the rectification system. An argon stripping column arrangement is also disclosed where residual argon is removed from the methane-rich fuel gas and recycled back to the feed stream.

A system and method for argon and nitrogen extraction from a feed stream comprising hydrogen, methane, nitrogen and argon, such as tail gas of an ammonia production plant is provided. The disclosed system and method provides for nitrogen-argon rectification and the methane rejection within a column system comprised of at least one distillation column. Nitrogen and argon are further separated and to produce liquid products. An argon stripping column arrangement is disclosed where residual argon is further removed from the methane-rich fuel gas and recycled back to the feed stream.

Enhancements to a dual column, nitrogen producing cryogenic air separation unit with waste expansion are provided. Such enhancements include an improved air separation cycle that uses: (i) three condenser-reboilers; (ii) a reverse reflux stream from the condenser-reboiler associated with the lower pressure column to the higher pressure column; and (iii) a recycle stream of a portion of the vapor from one or more of the condenser-reboilers that is recycled back to the incoming feed stream and or the compressed purified air streams to yield improvements in the performance of such dual column, nitrogen producing cryogenic air separation units in terms of overall nitrogen recovery as well as power consumption compared to conventional dual column, nitrogen producing cryogenic air separation units employing waste expansion.

A method and apparatus for producing a high-pressure gas from an air separation unit is provided, in which the method includes the steps of introducing a cold air feed into a distillation column system under conditions effective for separating the cold air feed into a first air gas and a second air gas; withdrawing the first and second air gases from the distillation column system and warming said first and second air gases in a main heat exchanger, wherein the first air gas is withdrawn from the distillation column system at a medium pressure; splitting the first air gas into a first fraction and a second fraction; expanding the first fraction in a turbine; and compressing the second fraction in a booster to a pressure that is higher than the medium pressure, wherein the booster is powered by the turbine