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 system for preparing subcooled liquid oxygen based on mixing of liquid oxygen and liquid nitrogen and then vacuum-pumping, including atmospheric-pressure saturated liquid nitrogen and oxygen tanks. An inlet of the liquid nitrogen tank communicates with pressurized gas, and an outlet is connected to an inlet a of a secondary subcooler. An inlet of the liquid oxygen tank communicates with the pressurized gas, and a first outlet is connected to an inlet b of the secondary subcooler. An outlet c of the secondary subcooler is connected to an inlet d of a primary subcooler. An outlet e of the primary subcooler is connected to a pumping-out device through a rewarming device. A second outlet of the liquid oxygen tank is connected to an inlet n of the primary subcooler. An outlet o of the primary subcooler is connected to an inlet r of the secondary subcooler.

The invention relates to a method and device for obtaining compressed oxygen and compressed nitrogen by the low-temperature separation of air in a distillation column system for nitrogen-oxygen separation, said distillation column system having at least one high-pressure column (8) and one low-pressure column (460), wherein the low-pressure column (460) is in a heat-exchanging connection with the high-pressure column (8) by means of a main condenser (461) designed as a condenser-evaporator. Feed air is compressed in an air compressor (2). The compressed feed air (6, 734, 802, 840) is cooled down in a main heat exchanger (20) and at least partially introduced into the high-pressure column (8). An oxygen-enriched liquid (462, 465) is removed from the high-pressure column (8) and fed to the low-pressure column (460) at a first intermediate position (464, 467, 906). A nitrogen-enriched liquid (468, 470) is removed from the high-pressure column (8) and/or the main condenser (461) and fed to the head of the low-pressure column (460). A liquid oxygen flow (11, 12) is removed from the distillation column system for nitrogen-oxygen separation, brought to an elevated pressure in the liquid state (13), introduced into the main heat exchanger (20) at said elevated pressure, evaporated or pseudo-evaporated and heated to approximately ambient temperature in the main heat exchanger (20), and finally obtained as a gaseous compressed oxygen product (14). A high-pressure process flow (34, 734) is brought into indirect heat exchange with the oxygen flow in the main heat exchanger (20) and then depressurized (36, 38; 736, 738), wherein the depressurized high-pressure flow (37, 737) is introduced at least partially in the liquid state into the distillation column system for nitrogen-oxygen separation. A gaseous circuit nitrogen flow (18, 19) is drawn from the high-pressure column and at least partially (21) compressed in a circuit compressor (22). A first sub-flow (45, 46; 244, 242, 230; 845, 846) of the circuit nitrogen flow is removed from the circuit compressor (22, 322), cooled down in the main heat exchanger (20), at least partially condensed in the bottom evaporator (9, 209) of the high-pressure column (8) in indirect heat exchange with the bottom liquid of the high-pressure column (8), and conducted back into the distillation column system for nitrogen-oxygen separation. A second sub-flow of the circuit nitrogen flow is branched

An improved process for liquid nitrogen production by cryogenic air separation using a distillation column system to enhance the product recovery.

A method for low-temperature air separation, in which an air-separation system having a column system is used that has a first column, a second column, a third column, and a fourth column, wherein fluid from the first column is fed at least into the second column, fluid from the second column is fed at least into the third column, fluid from the third column is fed at least into the fourth column, and fluid from the fourth column is fed at least into the third column, and wherein the fluid fed from the third column into the fourth column includes at least a portion of a side flow, which is withdrawn from the third column and has a lower oxygen content and a higher argon content than the third sump liquid. The present invention also relates to a corresponding system.

A plate fin heat exchanger assembly (S) for a cryogenic air separation unit, comprising: a heat exchanger having at least two cryogenic liquid inlets (B,C) at least two cryogenic liquid outlets (B,C), at least one nitrogen-rich stream inlet (D) at a first end of the heat exchanger and at least one nitrogen-rich stream outlet at a second end of the heat exchanger, the heat exchanger configured to receive a flow of at least one nitrogen-rich stream (WN,LPGAN) of the air separation unit at the at least one nitrogen-rich stream inlet and separate flows of at least two cryogenic liquids (LOX,LIN,LR) at the at least two cryogenic liquid inlets; wherein the inlet of the first of the cryogenic liquids is closer to the first end than the outlet of the second of the cryogenic liquids.

The invention relates to a method for a low-temperature air separation in which an air separation unit is used comprising a first rectification column and a second rectification column. The first rectification column is operated at a first pressure level, and the second rectification column is operated at a second pressure level below the first pressure level. Fluid which is oxygen-enriched compared to atmospheric air is drawn from the first rectification column in the form of one or more first material flows. At least one fraction of the fluid which has been drawn from the first rectification column in the form of the one or more first material flows is heated in a heat exchanger; a fraction of the fluid which has been heated in the heat exchanger is compressed using a compressor and is returned to the first rectification column.

A method of efficient cold recovery from a liquid hydrogen stream includes warming a cold liquid hydrogen stream by indirect heat exchange with a cold feed air stream in an ASU sub-cooler, thereby producing a warmed liquid hydrogen stream. Wherein at least a portion of the cool inlet air stream is introduced into a cold booster, thereby producing the compressed cool feed air stream. Wherein at least a first portion of the further cooled feed air stream is introduced into an expander, thereby producing an expanded feed air stream. Wherein a second portion of the further cooled feed air stream is further cooled, thereby producing the cold feed air stream. And, wherein the liquid oxygen stream has a first molar mass flow rate, and the cold liquid hydrogen stream has a second molar flow rate that is between 1.5 and 2.5 times the first molar mass flow rate.

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.

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.