A method for operating an air separation unit having both a startup phase and a steady-state operating phase is provided. The method can include the steps of: introducing a plurality of air streams into a cold box, wherein each stream is cooled in a heat exchanger and then sent to a system of distillation columns for separation therein by cryogenic distillation; producing a plurality of air gas streams from the system of distillation columns and warming said plurality of air gas streams in the heat exchanger; determining whether each stream of the plurality of air streams is a net cold producing stream or net cold consuming streams; and adjusting a flow rate of each stream of the plurality of air streams during the startup phase such that each stream that is a net cold producing stream has a higher flow rate during the startup phase as compared to the steady-state operating phase, and wherein each stream that is a net cold consuming stream has a lower flow rate during the startup phase as compared to the steady-state operating phase.

A polymerizable LC material comprising one or more reactive mesogenic compounds, one or more chiral compounds and a block copolymer that comprises at least one polyfluorooxetane block bonded to a polyether block, said polyfluorooxetane block having a repeating unit of the formula

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Further, a method for its preparation, a polymer film obtainable from a corresponding polymerizable LC material, a method of preparation of such polymer film, and the use of such polymer film and said polymerizable LC material in optical, electro-optical, decorative or security devices.

Process for vaporizing purge liquid from a cryogenic liquid vaporizer, the liquid containing at least one impurity, in which the purge liquid is withdrawn from a bath of liquid surrounding the vaporizer or resulting from the vaporizer, all of the purge liquid is vaporized in a heater, characterized in that the content of the at least one impurity in at least one portion, or even all of the heated vaporized liquid is analysed and the flow rate of at least one portion, or even all of the heated vaporized liquid is measured.

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.

Enhancements to a dual column, nitrogen producing cryogenic air separation unit are provided. Such enhancements include an improved air separation cycle that uses multiple condenser-reboilers and recycles a portion of the vapor from one or more of the condenser-reboilers to the incoming feed stream and or the compressed purified air streams to yield improvements in such dual column, nitrogen producing cryogenic air separation units. The multiple condenser-reboilers preferably include an integrated condenser-reboiler arrangement comprising a heat exchanger having a set of nitrogen condensing passages, a first set and second set of boiling passages, and a phase separator.

A method for starting up an air separation plant having a higher-pressure column, a lower-pressure column, and a falling film vaporizer disposed within a lower section of the lower-pressure column is provided. The method can include the steps of: introducing a cooled and compressed air stream into the higher pressure column; withdrawing an oxygen-enriched liquid stream from a bottom section of the higher-pressure column and introducing said oxygen-enriched liquid stream to an upper section of the lower-pressure column; and exchanging heat between nitrogen gas coming from a top section of the higher-pressure column and liquid oxygen from the lower-pressure column within the falling film vaporizer. During a start-up period, flow of liquid oxygen is at least reduced to the closed core. This reduces the available heat exchange area during start up, which increases ΔT and ΔP in the condenser/reboiler.

A method and apparatus for producing a high-pressure gas from an air separation unit is provided, in which the method includes the steps of introducing a cold air feed into a distillation column system under conditions effective for separating the cold air feed into a first air gas and a second air gas; withdrawing the first and second air gases from the distillation column system and warming said first and second air gases in a main heat exchanger, wherein the first air gas is withdrawn from the distillation column system at a medium pressure; splitting the first air gas into a first fraction and a second fraction; expanding the first fraction in a turbine; and compressing the second fraction in a booster to a pressure that is higher than the medium pressure, wherein the booster is powered by the turbine

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 method for obtaining one or more air products, wherein an air separation system having a rectification column system is used, in which pressurized air is processed in an adjustable total air volume, wherein the total air volume is set to a first value during a first operating period and set to a second value that is different from the first value during a second operating period, and wherein the setting of the total air volume is changed from the first value to the second value in a third operating period from a first time to a second time. The second operating period is after the first operating period, the third operating period is between the first operating period and the second operating period. In the third operating period, a setting of a volume of a fluid, is changed from a third time up to a fourth time.

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.