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 heat exchanger for indirect heat exchange between a first and a second fluids to be cooled and at least a third fluid to be heated, made up of a plurality of passages, namely a first series of passages for the flow at least of the first and of the second fluids, a second series of passages for the flow of the third fluid to be placed in a heat exchange relationship with the first and second fluids, the exchanger comprising three sections, the second section being between the first and third sections and means for introducing the first fluid into only a portion of the passages of the first series in the second section.

An air separation apparatus and process, which produces gaseous oxygen and/or nitrogen products at an elevated pressure through internal compression of respective liquid products, are disclosed. Split-core main heat exchangers are employed to warm up product streams generated in an air rectification unit against 1) a main feed air stream in the low-pressure heat exchanger and 2) at least one boosted pressure air stream in the high-pressure exchanger. Because the boosted pressure air stream is at a higher pressure and temperature than the main feed air stream, after separate heat exchange in the split main heat exchangers, the subsidiary waste nitrogen stream exiting the high-pressure heat exchanger is also warmer than the subsidiary waste nitrogen stream exiting the low-pressure heat exchanger. The warmer waste nitrogen stream is fed into the air purification unit for regeneration purposes and the cooler waste nitrogen stream is introduced into the nitrogen water tower to perform cooling duty. The two subsidiary waste nitrogen streams are also connected on the warm side of the main heat exchangers to allow flexible distribution of the flow.

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 for controlling a coupled heat exchanger system having a first heat exchanger block and a second heat exchanger block. A first fluid stream is divided into a first partial current and a second partial current both flowing through the heat exchanger system. A second fluid stream flows through the first heat exchanger block counter to the first partial current. A third fluid stream flows through the second heat exchanger block counter to the second partial current. An intermediate temperature is measured on one of the heat exchanger blocks. The amount of the first partial current and the second partial current is controlled based on the current value of the intermediate temperature. This control reduces the strain on the heat exchangers by changing loads while keeping fluctuations of the intermediate temperature low.

A method and device to produce oxygen by the low-temperature separation of air at variable energy consumption. A distillation column system comprises a high-pressure column, a low-pressure column and a main condenser, a secondary condenser and a supplementary condenser. Gaseous nitrogen from the high-pressure column is liquefied in the main condenser in indirect heat exchange with an intermediate liquid from the low-pressure column. A first liquid oxygen stream from the bottom of the low-pressure column is evaporated in the secondary condenser in indirect heat exchange with feed air to obtain a gaseous oxygen product. The supplementary condenser serves as a bottom heating device for the low-pressure column and is heated by means of a first nitrogen stream from the distillation column system, which nitrogen stream was compressed previously in a cold compressor.

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 a method for separating air by cryogenic distillation using a column system consisting of a higher pressure column operating at a first pressure and a lower pressure column operating at a second pressure, a first air flow constituting between 75% and 98% of the air sent to the column system compressed to a third pressure above the first pressure, is sent to the higher pressure column, a second air flow constituting between 5% and 25% of the air sent to the column system is compressed to a fourth pressure above the second pressure but lower than the third pressure, is sent to the lower pressure column, a third column separates an argon-enriched flow and the air sent to the lower pressure column constitutes between 10% and 25% of the total air sent to the column system.

An apparatus for the separation of air by cryogenic distillation comprises a column system, a heat exchanger, a turbine, means for sending compressed and purified air at a first pressure to be cooled at the first pressure in the heat exchanger, means for sending a first gaseous stream having a nitrogen content at least that of air to be cooled and liquefied or pseudo liquefied in the heat exchanger to form a liquefied stream, means for sending at least part of the liquefied stream to be warmed and vaporized in the heat exchanger to a first intermediate temperature of the heat exchanger to form a vaporized stream, means for removing the vaporized stream from an intermediate section of the heat exchanger, a conduit for sending the vaporized stream to be expanded, in the turbine to form an expanded stream, a conduit for sending at least part of the expanded stream to the column system, a conduit for sending a second gaseous stream having the same nitrogen content as the first stream to be cooled in the heat exchanger, means for removing at least part of the second gaseous stream from an intermediate section of the heat exchanger at a second intermediate temperature and sending the second gaseous stream to the turbine to be expanded with the vaporized stream.

Integration of a natural gas liquefaction system, a hydrogen production system, and power generation system to increase CO2 capture and improve overall plant efficiency. The predominantly methane endflash is sent to the hydrogen production system which produces hydrogen and CO2. The CO2 may be captured or beneficially used. At least a portion of the hydrogen produced is used to fuel gas turbines in the power generation which, in turn, provides power for the refrigeration compressor of the natural gas liquefaction system—either in the form of mechanical work or electricity.