An air separation unit using cryogenic distillation comprises a first column, a second column thermally linked to the first column, a first argon column, a second argon column, means for sending cooled, compressed and purified air to at least the first column, means for sending at least one fluid enriched in nitrogen from the first column to the second column and at least one fluid enriched in oxygen from the first column to the second column, means for sending a gas enriched in argon from the second column to a first end of the first argon column, means for sending gas from a second end of the first argon column to a first end of the second argon column, means for removing argon rich fluid from a second end of the second argon column, a pump, means for removing argon enriched liquid from the first end of the second argon column and sending it to the second end of the first argon column via the pump, the first end of the first argon column being raised above the ground by a first supporting structure, the pump being positioned within the first supporting structure, such that the pump is at least partially underneath the first end of the first argon column.

In this process and apparatus for cryogenic separation of air, the separation column system comprises a high-pressure column, a low-pressure column and a crude argon column. A mixed gas stream produced by mixing gaseous oxygen and a gas stream from the evaporation space of the argon top condenser, is work expanded in a mixed gas turbine.

An air separation device according to the present invention is an air separation device in which air is distilled at a low temperature, and includes a high-pressure column which separates high-pressure raw material air into high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air; a low-pressure column which separates the high-pressure oxygen-enriched liquefied air into low-pressure nitrogen gas, low-pressure liquefied oxygen, and argon-enriched liquefied oxygen; an argon column which separates the argon-enriched liquefied oxygen having a pressure higher than the pressure into argon gas and medium-pressure liquefied oxygen; a first indirect heat-exchanger which heat-exchanges between the argon gas and the low-pressure liquefied oxygen; a second indirect heat-exchanger which heat-exchanges between the high-pressure nitrogen gas and the medium-pressure liquefied oxygen; a first gas-liquid separation chamber which separates the low-pressure oxygen gas which has been vaporized by the first indirect heat-exchanger and the low-pressure liquefied oxygen which has not been vaporized; a second gas-liquid separation chamber which separates the medium-pressure oxygen gas which has been vaporized by the second indirect heat-exchanger and the medium-pressure liquefied oxygen which has not been vaporized; a first passage which communicates the gas phase of the low-pressure column and the gas phase of the second gas-liquid separation chamber; a second passage which communicates the liquid phase of the low-pressure column and the second gas-liquid separation chamber; a first opening/closing mechanism located on the first passage; and a second opening/closing mechanism located on the second passage.

A method for flexible production of argon from a cryogenic air separation unit is provided. The disclosed 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.

The present invention relates to a process and a system for supplying a backup gas at a higher pressure from a source gas at a lower pressure. The backup gas at the lower pressure is at least partially condensed against a backup liquid at a higher pressure in a reprocessing heat exchanger and as a result, the backup liquid is at least partially vaporized. The backup liquid at the higher pressure is formed from boosting liquefied backup gas at the lower pressure. A backup vaporizer is disposed downstream of the reprocessing heat exchanger to completely vaporize the backup liquid at a higher pressure before it was delivered to the customer. The present invention eliminates the use of costly gas compressor and mitigates associated safety risks, in particular when the backup gas is oxygen.

A unit for producing argon by cryogenic distillation, suitable for connection to a double air separation column consisting of first and second columns interconnected thermally, comprises an argon separation column surmounted with a top condenser and a denitrogenation column, means for withdrawing an argon-rich and nitrogen-depleted product (LAR) at the bottom of the denitrogenation column, means for connecting the top of the argon separation column to the denitrogenation column, means for sending a top gas from the argon separation column to the atmosphere, means for withdrawing a nitrogen-rich fluid from the top of the denitrogenation column, an analyser for measuring the nitrogen content at the top of the argon separation column, and means for opening and closing the means for connecting the top of the argon separation column to the denitrogenation column depending on the nitrogen content detected by the analyser.

In a method for separating air by cryogenic distillation, cooled air purified to remove water is sent to a first column operating at a first pressure, where it is separated into a nitrogen-enriched gas as an oxygen-enriched liquid; a gas enriched in argon relative to the air is withdrawn from the second column; at least a portion of the oxygen-enriched liquid is vaporized by heat exchange with the argon-enriched gas; and the vaporized, oxygen-enriched liquid is sent to an intermediate level of the second column.

An air separation unit using cryogenic distillation comprises a first column, a second column thermally linked to the first column, a first argon column, a second argon column, means for sending cooled, compressed and purified air to at least the first column, means for sending at least one fluid enriched in nitrogen from the first column to the second column and at least one fluid enriched in oxygen from the first column to the second column, means for sending a gas enriched in argon from the second column to a first end of the first argon column, means for sending gas from a second end of the first argon column to a first end of the second argon column, means for removing argon rich fluid from a second end of the second argon column, a pump, means for removing argon enriched liquid from the first end of the second argon column and sending it to the second end of the first argon column via the pump, the first end of the first argon column being raised above the ground by a first supporting structure, the pump being positioned within the first supporting structure, such that the pump is at least partially underneath the first end of the first argon column.

A system and method for argon production in an air separation plant facility or enclave having multiple cryogenic air separation units is provided. The present system and method include a centralized argon refining system disposed within one of the cryogenic air separation units and which is configured to include an argon superstaged or ultra-superstaged column arrangement having one or more argon columns and an argon condenser. Crude argon streams from one or more of the other cryogenic air separation units are directed to the argon superstaged or ultra-superstaged column arrangement of the centralized argon refining process.

A moderate pressure, argon and nitrogen producing cryogenic air separation unit and air separation cycle having a higher pressure column, a lower pressure column and an argon column arrangement is disclosed. The moderate pressure, argon and nitrogen producing cryogenic air separation unit is configured to take a first portion of an oxygen enriched stream from the lower pressure column, which together with an external source of liquid nitrogen is used as the boiling side refrigerant to condense the argon in the argon condenser. Use of the external source of liquid nitrogen in the argon condenser allows a second portion of the oxygen enriched stream from the lower pressure column to be taken as a liquid oxygen product stream.