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 for obtaining one or more air products by means of an air separation unit comprising a first booster, a second booster, a first decompression machine, and a rectification column system which has a high-pressure column operated at a first pressure level and a low-pressure column operated at a second pressure level below the first pressure level. All of the air supplied to the rectification column system is first compressed to a third pressure level, which lies at least 3 bar above the first pressure level, as a feed air quantity. A first fraction of the feed air quantity is supplied to a first booster at the third pressure level and at a temperature level of −140 to −70 ° C. and is compressed to a fourth pressure level using the first booster.

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 and the apparatus for the cryogenic separation of air in an air separation plant which has a main air compressor, a main heat exchanger and a distillation column system with a high-pressure column and a low-pressure column. All of the feed air is compressed in the main air compressor to a first air pressure which is at least 3 bar higher than the operating pressure of the high-pressure column. A first part of the compressed total air flow, as first air flow at the first air pressure, is cooled and liquefied or pseudo-liquefied in the main heat exchanger, then expanded and introduced into the distillation column system. A second part of the compressed total air flow, as second air flow, is post-compressed in an air post-compressor to a second air pressure and at least part is further compressed in a first turbine-driven post-compressor to a third air pressure.

Enhancements to a dual column, nitrogen producing cryogenic air separation unit with waste expansion are provided. Such enhancements include an improved air separation unit arrangement that uses: (i) three condenser-reboilers; (ii) a reverse reflux stream from the condenser-reboiler associated with the lower pressure column to the higher pressure column; (iii) a waste expansion cycle, and (iv) a recycle stream of a portion of the boil off vapor from one or more of the condenser-reboilers. The improved air separation cycle minimizes the backpressure of the lower pressure column and yields improvements in the nitrogen recovery as well as reductions in unit power consumption compared to conventional dual column, nitrogen producing cryogenic air separation units employing waste expansion.

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 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.

A gas production system that can supply liquefied gas obtained by rectifying source gas as product gas continuously with high heat efficiency without using a machine that has a risk of contamination like a pump. A gas production system includes a single pressure device having a single pressurized container to which liquefied gas extracted from a rectification unit is supplied, a pressure line for extracting and vaporizing a part of the liquefied gas in the pressurized container and returning the part of the liquefied gas to the pressurized container, and a second heat exchange unit that is disposed in the pressure line, and a liquefied gas storage unit that stores liquefied gas which is led out from the pressurized container.

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.