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.

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.

A method for low temperature separation of air using an air separating installation having a distillation column system which has a first, a second, a third and a fourth separating unit. Compressed and cooled air is fed into the first separating unit. An oxygen-enriched, nitrogen-depleted, argon-containing first sump liquid and a nitrogen-enriched, oxygen-depleted first head gas are formed by means of the first separating unit. An oxygen-rich second sump liquid and an argon-enriched second head gas are formed by means of the second separating unit. A liquid return to the second separating unit is provided by means of the third separating unit. A fourth sump liquid and a fourth head gas are formed by means of the fourth separating unit, and the fourth sump liquid is at least partially returned to the second separating unit.

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.

The invention proposes a process and an air separation plant comprising a rectification column system comprising a high-pressure column, a low-pressure column, a main heat exchanger, and a main air compressor. The total air supplied to the rectification column system is compressed in the main air compressor to a first pressure level. The high-pressure column is operated at a second pressure level, at least 3 bar below the first pressure level. A gaseous, nitrogen-rich fluid is removed from the high-pressure column and warmed up in the gaseous state without prior liquefaction. A first partial quantity of the gaseous, nitrogen-rich fluid is warmed to a first temperature level of −150 to −100° C., supplied at this first temperature level to a booster and compressed further to a third pressure level. The first partial quantity is then warmed to a second temperature level and discharged from the air separation plant.

The invention relates to a system for controlling an argon flow rate of a fluid at the outlet of an assembly of at least one distillation column in order to reach a target dioxygen level (SP). The system comprises: a sensor arranged so as to measure a dioxygen level (PV) in a fluid containing argon at the outlet of the assembly of at least one distillation column; a regulator arranged so as to determine a required argon flow rate variation (Δ.sub.regul) according to the difference between the dioxygen level measured by the sensor and a target dioxygen level; a controller arranged so as to generate a control signal relating to a targeted argon flow rate, said targeted argon flow rate being determined according to the required argon flow variation determined by the regulator and variations in the dioxygen level measured by the sensor; and a valve, controlled by said controller, which is arranged so as to modify the argon flow rate of the fluid at the outlet of at least one distillation column in order to achieve the targeted argon flow rate.

A method and the apparatus for obtaining a compressed gas product by means of cryogenic separation of air in a distillation column system which has a high-pressure column and a low-pressure column. All of the feed air is compressed in a main air compressor to a first pressure which is at least 4 bar higher than the operating pressure of the high-pressure column. A first partial flow of the feed air compressed in the main air compressor is cooled to an intermediate temperature in a main heat exchanger and is expanded so as to perform work in a first air turbine. At least a first part of the first partial flow expanded so as to perform work is introduced into the distillation column system.

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.

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.