The invention relates to a cryogenic distillation apparatus for a gas mixture, including a purification apparatus for purifying a gas mixture in a system with a plurality of adsorbant bottles, a column system, a capacity, means for feeding a cryogenic liquid to the capacity, means for feeding a vaporized liquid from the capacity to a column of the system, a vaporizer in the capacity for vaporizing the contained liquid; means for feeding a calorigenic gas to the vaporizer, and means for drawing a liquid from the capacity.

An air separation plant is provided that includes a plurality of air compressors, a plurality of air purification units, and one or more cold boxes. In a first mode of operation, a first air compressor is configured to compress air to a higher pressure than a second air compressor. In a second mode of operation, the second air compressor is configured to compress air to a higher pressure than during the first mode of operation.

An air separation plant is provided that includes a plurality of air compressors, a plurality of air purification units, and one or more cold boxes. In a first mode of operation, a first air compressor is configured to compress air to a higher pressure than a second air compressor. In a second mode of operation, the second air compressor is configured to compress air to a higher pressure than during the first mode of operation.

A process for recovery of natural gas liquids is disclosed, the process including: fractionating a gas stream comprising nitrogen, methane, ethane, and propane and other C.sub.3+ hydrocarbons into at least two fractions including a light fraction comprising nitrogen, methane, ethane, and propane, and a heavy fraction comprising propane and other C.sub.3+ hydrocarbons; separating the light fraction into at least two fractions including a nitrogen-enriched fraction and a nitrogen-depleted fraction in a first separator; separating the nitrogen-depleted fraction into a propane-enriched fraction and a propane-depleted fraction in a second separator; feeding at least a portion of the propane-enriched fraction to the fractionating as a reflux; recycling at least a portion of the propane-depleted fraction to the first separator. In some embodiments, the nitrogen-enriched fraction may be separated in a nitrogen removal unit to produce a nitrogen-depleted natural gas stream and a nitrogen-enriched natural gas stream.

Disclosed is a method for purifying a main gas, in particular helium, from a source gas stream comprising the main gas, a main impurity, in particular nitrogen, and optionally another, secondary impurity, in particular oxygen, the method comprising a step of partial condensation of the gas stream in order to extract therefrom impurities in liquid form, in particular the main impurity, and to produce a gas stream enriched with main gas, characterized in that the method comprises, before the partial condensation step, a step of injecting into the gas stream a compound in which the main impurity of the gas to be treated is soluble and having a saturation vapor pressure lower than the saturation vapor pressure of the main impurity.

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.

An air separation unit and associated method for separating air by cryogenic distillation using a distillation column system including a higher pressure column, a lower pressure column, an intermediate pressure kettle column, and an argon column arrangement is provided. The present air separation unit and associated method employs a once-through kettle column reboiler, a once-through kettle column condenser, and a once-through argon condenser. The once through argon condenser is disposed within the lower pressure column where an argon-rich vapor stream is condensed against the descending liquid in the lower pressure column.

Described herein are methods and systems for removing natural gas liquids from a natural gas feed stream and for liquefying the natural gas feed stream so as to produce a liquefied natural gas (LNG) stream and a natural gas liquids (NGL) stream.

A process and apparatus for recovering at least argon from a feed gas that can provide an improved recovery of argon as well as an improvement in operational efficiency. Some embodiments can be adapted so that the improved argon recovery can also be obtained with improved condenser operation for an argon column without requiring an increase in power for the recovery of the argon. Some embodiments can utilize a reboiler positioned near or at the bottom of argon recovery column to increase boil-up therein and/or provide added heat duty to drive a condenser of the argon recovery column to provide improved argon recovery.

A method for operating an air separation plant having a distillation column system, a heat exchanger, and an adsorber, wherein, in a first time period, a first operating mode is carried out and, in a second time period following the first time period, a second operating mode is carried out. In a third time period between the second time period and the first time period, a third operating mode is carried out, in which third operating mode compressed air is at least partially freed of water and carbon dioxide in the adsorber and at least part of said compressed air is cooled in the heat exchanger, an air product is removed from the distillation column system and at least part of said air product is heated in the heat exchanger.