A system and method for producing two or more nitrogen product streams and a crude argon stream from a nitrogen and argon producing air separation unit is provided. The disclosed embodiments of the cryogenic-based nitrogen and argon producing air separation units and associated air separation cycles include the means for directing a first portion of a boil-off stream from an argon condenser of the air separation unit to a waste expansion refrigeration circuit and concurrently recycling a second portion of the boil-off stream from the argon condenser to the main air compression system of the air separation unit to be mixed or blended with the incoming feed air. Optionally, a third portion of the boil-off stream from the argon condenser may be further compressed in a cold compressor and returned to the lower pressure column.

A method and apparatus for separating air in which an oxygen-rich liquid stream is pumped and then heated within a heat exchanger to produce an oxygen product through indirect heat exchange with first and second boosted pressure air streams. The first boosted pressure air stream is cold compressed at an intermediate temperature of the heat exchanger, reintroduced into the heat exchanger at a warmer temperature and then fully cooled and liquefied. The second boosted pressure air stream, after having been partially cooled, is expanded to produce an exhaust stream that is in turn introduced into a lower pressure column producing the oxygen-rich liquid. The second boosted pressure air stream is partially cooled to a temperature no greater than the intermediate temperature at which the cold compression occurs so that both the first and second boosted pressure air streams are able to take part in the heating of the oxygen-rich stream.

A cryogenic air separation apparatus comprises: a heat exchanger, a first rectification column, a first condenser, a second rectification column, a third rectification column, a second condenser, a high-purity oxygen rectification column, a third condenser, a nitrogen compressor, and a compressed recycled gas line L52 for introducing product nitrogen gas compressed by the first nitrogen compressor into a warm end (heat source) of an ultra-high-purity oxygen vaporizer as a compressed recycled gas.

Disclosed in the present invention are a pressure equalizing system for air separation purification, and a control method. The system comprises: a first air main pipe; a pressurizing gas pipeline, which is connected to the first air main pipe and used for receiving a pressurizing gas and delivering same to the first air main pipe; and a control valve, located on the pressurizing gas pipeline, and having a degree of opening regulated by the flow regulator, thereby regulating an air intake amount of the pressurizing gas pipeline. The present invention solves the problem of an air separation rectification process being affected when dry nitrogen is used for pressure equalization of an adsorber; in the switching process of entering an adsorption stage from a regeneration stage, pressurizing dry nitrogen used in a pressure equalizing step previously mixes with damp air from a main air compressor before entering the adsorber, such that the gas components flowing towards an air separation cold box remain substantially unchanged, in order to reduce disturbance in conditions of gas entering a rectification column to take part in rectification due to a gas component gradually changing from dry nitrogen to dry air in the prior art, thus stabilizing the process conditions of the air separation cold box.

The present invention relates to an adsorption process for xenon recovery from a cryogenic liquid or gas stream wherein a bed of adsorbent is contacted with a xenon-containing liquid or gas stream selectively adsorbing the xenon from said stream. The adsorption bed is operated to at least near full breakthrough with xenon to enable a deep rejection of other stream components, prior to regeneration using the temperature swing method. After the stripping step, the xenon adsorbent bed is drained to clear out the liquid residue left in the nonselective void space and the xenon molecules in those void spaces is recycled upstream to the ASU distillation column for increasing xenon recovery. The xenon adsorbent bed is optionally purged with oxygen, followed by purging with gaseous argon at cryogenic temperature (≤160 K) to displace the oxygen co-adsorbed on the AgX adsorbent due to higher selectivity of argon over oxygen on the AgX adsorbent. By the end of this step, the xenon adsorbent bed is filled with argon and xenon. Then the entire adsorbent bed is heated indirectly without utilizing any of the purge gas for direct heating. Operating the adsorption bed to near full breakthrough with xenon and displacing the adsorbed oxygen and other residues with argon, prior to regeneration, along with indirect heating of the bed, enables production of a high purity product ≥40 vol % xenon from the adsorption bed and further enables safely heating without any purge gas and ease for downstream product collection, even in cases where hydrocarbons are co-present in the feed stream.

A system and method for flexible production of argon from a cryogenic air separation unit is provided. The cryogenic air separation unit is capable of operating in a ‘no-argon’ or ‘low-argon’ mode when argon demand is low or non-existent and then switching to operating in a ‘high-argon’ mode when argon is needed. The recovery of the argon products from the air separation unit is adjusted by varying the percentages of dirty shelf nitrogen and clean shelf nitrogen in the reflux stream directed to the lower pressure column. The cryogenic air separation unit and associated method also provides an efficient argon production/rejection process that minimizes the power consumption when the cryogenic air separation unit is operating in a ‘no-argon’ or ‘low-argon’ mode yet maintains the capability to produce higher volumes of argon products at full design capacity to meet argon product demands.

A method and device to variably obtain argon by means of low-temperature separation. Feed air is cooled in a main heat exchanger and then conducted into a distillation column system with a high-pressure column and a low-pressure column. Argon is obtained using a crud argon column and a purified argon column. A purified liquid argon product flow is generated from an argon-enriched flow from the low-pressure column. In a first operating mode, a first quantity of purified argon product is discharged, and in a second operating mode, a reduced quantity of purified argon product is discharged. In the second operating mode, a gaseous argon return flow is drawn from the crude argon column or the purified argon column and heated in a separate passage of the main heat exchanger.

A liquefier device which may be a retrofit to an air separation plant or utilized as part of a new design. The flow needed for the liquefier comes from an air separation plant running in a maxim oxygen state, in a stable mode. The three gas flows are low pressure oxygen, low pressure nitrogen, and higher pressure nitrogen. All of the flows are found on the side of the main heat exchanger with a temperature of about 37 degrees Fahrenheit. All of the gasses put into the liquefier come out as a subcooled liquid, for storage or return to the air separation plant. This new liquefier does not include a front end electrical compressor, and will take a self produced liquid nitrogen, pump it up to a runnable 420 psig pressure, and with the use of turbines, condensers, flash pots, and multi pass heat exchangers. The liquefier will make liquid from a planned amount of any pure gas oxygen or nitrogen an air separation plant can produce.

A method and apparatus for transferring a first liquid removed from an outlet of a first distillation column to an inlet of a second distillation column is provided. The second distillation column operates at a higher pressure than the first distillation column, and the inlet of the second distillation column is at higher elevation as compared to the outlet of the first distillation column. The method advantageously transfers the first liquid from the outlet to the inlet by mixing with a sufficient amount of a lower density second liquid that results in a mixed liquid having a reduced density as compared to the first liquid.

A system and method for flexible production of argon from a cryogenic air separation unit is provided. The cryogenic air separation unit is capable of operating in a ‘no-argon’ or ‘low-argon’ mode when argon demand is low or non-existent and then switching to operating in a ‘high-argon’ mode when argon is needed. The recovery of the argon products from the air separation unit is adjusted by varying the percentages of dirty shelf nitrogen and clean shelf nitrogen in the reflux stream directed to the lower pressure column. The cryogenic air separation unit and associated method also provides an efficient argon production/rejection process that minimizes the power consumption when the cryogenic air separation unit is operating in a ‘no-argon’ or ‘low-argon’ mode yet maintains the capability to produce higher volumes of argon products at full design capacity to meet argon product demands.