A method for operating an air separation plant having a distillation column system, a heat exchanger, and an adsorber, wherein, in a first time period, a first operating mode is carried out and, in a second time period following the first time period, a second operating mode is carried out. In a third time period between the second time period and the first time period, a third operating mode is carried out, in which third operating mode compressed air is at least partially freed of water and carbon dioxide in the adsorber and at least part of said compressed air is cooled in the heat exchanger, an air product is removed from the distillation column system and at least part of said air product is heated in the heat exchanger.

A full liquid-product air separation equipment is disclosed. The equipment comprises an air filtration system, a compression system, a precooling system, a purification system, a high-temperature expander having a first pressurizing part and a first expanding part, a low-temperature expander having a second pressurizing part and a second expanding part, a main heat exchanger having a first heat exchange pipeline, a second heat exchange pipeline, a third heat exchange pipeline, a fourth heat exchange pipeline and a fifth heat exchange pipeline, and a rectification system for rectifying air. The equipment has a simple configuration, is easy to implement, and has high gas separation efficiency and low energy consumption.

A nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

A method is provided for determining a state of a distillation column having multiple column stages for separating a feed fluid stream into individual fluid components. The state is determined by means of a model in a manner dependent on pressure differences prevailing between adjacent column stages. In the model, both gaseous and liquid flows between adjacent column stages are brought about by the pressure differences prevailing between adjacent column stages. A substance quantity flow characterizing gaseous flow between two column stages is given by {dot over (N)}.sub.V.Math.R.sub.V=C.sub.V.Math.Δp.sub.V. A substance quantity flow characterizing liquid flow between two column stages is given by {dot over (N)}.sub.L.Math.R.sub.L=C.sub.L.Math.Δp.sub.L. Δp.sub.V,L is a total pressure difference between two adjacent column stages. R.sub.V,L is a coefficient of resistance between two adjacent column stages and C.sub.V,L is a conductance value of flow between two adjacent column stages.

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 ##STR00001## 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 nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

A nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

A method for operating a heat exchanger, in which a first operating mode is carried out in first time periods, and a second operating mode is carried out in second time periods that alternate with the first time periods; in the first operating mode a first fluid flow is formed at a first temperature level, is fed into the heat exchanger in a first region at the first temperature level, and is partially or completely cooled in the heat exchanger; in the first operating mode a second fluid flow is formed at a second temperature level, is fed into the heat exchanger in a second region at the second temperature level, and is partially or completely heated in the heat exchanger. A corresponding arrangement and a system with such an arrangement are also covered by the present invention.

The invention relates to a process for cryogenic fractionation of air using an air fractionation plant comprising a rectification column system comprising a high-pressure column operated at a pressure level of 9 to 14.5 bar, a low-pressure column operated at a pressure level of 2 to 5 bar, and an argon column. It is envisaged that a recirculating stream is formed using the second tops gas or a portion thereof, which is heated, compressed, cooled again, and after partial or complete liquefaction or in the unliquefied state is introduced partially or completely, or in fractions, into the first rectification column and/or into the second rectification column. The present invention also relates to a corresponding system.

A method and device to variably obtain argon by means of low-temperature separation. Feed air is cooled in a main heat exchanger and then conducted into a distillation column system with a high-pressure column and a low-pressure column. Argon is obtained using a crud argon column and a purified argon column. A purified liquid argon product flow is generated from an argon-enriched flow from the low-pressure column. In a first operating mode, a first quantity of purified argon product is discharged, and in a second operating mode, a reduced quantity of purified argon product is discharged. In the second operating mode, a gaseous argon return flow is drawn from the crude argon column or the purified argon column and heated in a separate passage of the main heat exchanger.