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.

A method for configuring a control system for a process plant using a dynamic model of the process plant, the dynamic model being based on at least one of thermo fluidic correlations, thermo dynamic correlations, phenomenological correlations, and equations, and being based on geometry and/or topology of components of the process plant, the dynamic model receiving process parameters as input values, the dynamic model being adapted to represent a transition from one to another state of the process plant and the dynamic model covering the entire operating range of the process plant wherein the dynamic model is used in an offline mode, in which the dynamic model is used in stand-alone fashion, wherein, based on input and output values of the dynamic model, a behaviour of the process plant is predicted, and wherein, based on the predicted behaviour of the process plant, the control system is configured.

A method for operating a process plant using a dynamic model of the process plant, the dynamic model being based on at least one of thermo fluidic correlations, thermo dynamic correlations, phenomenological correlations, and equations, and being based on geometry and/or topology of components of the process plant, the dynamic model receiving process parameters as input values, the dynamic model being adapted to represent a transition from one to another state of the process plant, wherein the dynamic model is used in an online mode, in which the dynamic model is used in parallel with the operation of the process plant, wherein signals from a control system of the process plant, the signals representing values of at least one first process parameter, are received and fed into the dynamic model.

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.

A moderate pressure nitrogen and argon producing cryogenic air separation unit is provided that includes a three distillation column system and turbine air stream bypass arrangement or circuit. The turbine air stream bypass arrangement or circuit is configured to improve argon and nitrogen recoveries in select operating modes by optionally diverting a portion of the turbine air stream to a nitrogen waste stream circuit drawn from the lower pressure column of the cryogenic air separation unit such that the diverted portion of the turbine air stream bypasses the distillation column system.

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.

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.

A moderate pressure air separation unit and air separation cycle is disclosed that provides for up to about 96% recovery of argon, an overall nitrogen recovery of 98 percent or greater and limited gaseous oxygen production. The air separation is configured to produce a first high purity oxygen enriched stream and a second lower purity oxygen enriched stream from the lower pressure column, one of which is used as the refrigerant to condense the argon in the argon condenser, with the resulting vaporized oxygen stream used to regenerate the temperature swing adsorption pre-purifier unit. All or a portion of the first high purity oxygen enriched stream is vaporized in the main heat exchanger to produce the gaseous oxygen products.

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.

The air separation system can include: a process control unit 201 for controlling components constituting the air separation system; an oxygen concentration estimating unit 202 for estimating, by calculation, the oxygen concentration of oxygen-enriched liquid that accumulates in a column bottom portion of the higher-pressure column; a flow rate estimating unit for estimating, by calculation, the flow rate of oxygen-enriched liquid that has been discharged from the column bottom portion of the higher-pressure column and that is to be introduced into a distillation portion of the lower-pressure column; and a target temperature calculating unit for calculating a target temperature of an argon extraction portion on the basis of the flow rate of feed air that has passed through at least a portion of the main heat exchanger 1 and that is to be sent to an expansion turbine, the oxygen concentration of the oxygen-enriched liquid, and the flow rate of the oxygen-enriched liquid.