Linde Aktiengesellschaft

Linde Gas Aktiengesellschaft

Wilhelm Rohde

Horst Corduan

Anton Moll

J&uuml;rgen Voit

Hannsjorg Koch

Michael Metschl

Erich Hahn

Gunter Klein, Deceased

Hans Wimber

Jorg Reyhing

The invention relates to a method for extracting xenon and eventually also krypton from a liquid oxygen (LOX) charge, as it accrues in a cryogenic air separation system (LZA) during a rectification of the air, mostly as a bottom product of a low-pressure, column, namely with xenon (Xe), krypton (Kr) and hydrocarbons (C H ) in a small concentration and approximately 99 mol % oxygen (O ). According to the inventive method, the LOX charge is fed to a first column, the oxygen of the LOX charge is extensively removed by stripping with an inert gas, and is extracted in the top gas, whereas the inert gas is withdrawn in the form of a liquid from the bottom of the first column with little O and nearly the total mass of C H , Kr, Xe. According to the invention, the liquid discharge is fed to a second column without prior catalytic and/or adsorptive removal of C H . A Kr fraction is extracted as top gas of the second column, and an Xe fraction is withdrawn from the bottom of the second column. The method can be used in a device for extracting Xe and/or Kr in an air separation system (LZA). The device can be arranged in a transportable container.

Method for extracting xenon

An method for the recovery of oxygen at hyperbaric pressure by low-temperature air fractionation includes compressing feed air to a first pressure, which is about the same as the operating pressure of the pressure column. At least a first partial flow of the feed air is cooled in a main heat exchanger and passed into the pressure column. An oxygen flow is tapped from the low-pressure column; brought to a delivery pressure that is higher than the operating pressure of the low-pressure column; heated in the main heat exchanger; and discharged as product. The pressure of a process stream from the main heat exchanger is relieved in a work-expanding manner, and the process stream is supplied to the low-pressure column. At least a portion of the mechanical energy generated by the work-expanding is used to drive a cold compressor. The flow of liquid oxygen from the low-pressure column is brought to the delivery pressure, and the oxygen is then evaporated by indirect heat exchange with a second partial flow of feed air, which has been compressed to the first pressure. The second partial flow is brought to a second pressure by the cold compressor upstream of the indirect heat exchange.

Method and apparatus for recovering oxygen at hyperbaric pressure

The device and the process are used to evaporate a liquid. A first (7) and a second (9) heat exchanger contain evaporation passages and passages for a heat transfer fluid. First heat exchanger (7) is designed as a falling film evaporator, second heat exchanger (9) is designed as a liquid bath evaporator. First heat exchanger (7) has means (13, 14) to introduce heat transfer fluid and means to drain heat transfer fluid. Second heat exchanger (9) includes means to introduce heat transfer fluid. The flow of the means for draining heat transfer fluid from first heat exchanger (7) is connected to the flow of the means for introducing heat transfer fluid into second heat exchanger (9). The equipment and the device can be used in a process for low-temperature separation of air that has a double column consisting of a pressure column (2) and a low-pressure column (3), and the equipment is used for evaporating liquid (5, 6) from the lower section of low-pressure column (3) in indirect heat exchange (7, 9) against condensing vapor (13, 14) from the upper area of pressure column (2).

Device and process for evaporating a liquid

Process for the low temperature separation of air and air separation

A process and apparatus for recovery of pure argon from air utilize a rectification system comprising at least one air separating column (9) and a pure argon column (25). An argon-enriched mixture (24) of air gases is introduced into the pure argon column (25) in the lower region of which an essentially nitrogen-free argon product (26) is recovered. The head fraction (28) of the pure argon column (25), is liquefied at least partly by indirect heat exchange (29) using the evaporating cooling medium (11, 30). The condensate (28a) formed thereby is returned into the pure argon column. The indirect heat exchange (29) is carried out by means of a cooling medium (11, 30) which has an oxygen content of at least 10%. Independently thereof, the lower region of the pure argon column (25) is heated by indirect heat exchange (27) by means of a heating medium (11) in a liquid state, for example, with sump liquid from a pressure column (8).

Process and apparatus for recovery of pure argon

For the low-temperature fractionation of air, especially for the production of medium purity oxygen, the entire feed air (1) is compressed in a first compressor stage (2) and purified by adsorption (4). A first component stream (101) of the air is introduced into the high-pressure stage (7) of a two-stage rectifying column (6). A second component stream is passed to the low-pressure stage (8), and this stream is separated, after adsorption (4), from the remaining feed air, heated against compressed feed air (3), and engine-expanded (13). The thus-produced work is utilized at least in part for the compression (2) of feed air.

Process for low-temperature air fractionation

For the low temperature fractionation of air with variable oxygen production, compressed, prepurified, and cooled air (conduit 5) is initially fractionated in the high pressure stage 10 of a two-stage rectification 9. The thus-produced bottom liquid is further separated in the low pressure stage 11. Liquid nitrogen 14 from the high pressure stage 10 and liquid oxygen from the low pressure stage 11 can be stored intermediarily in tanks 35 and 32. An enriched liquid air tank 40 is additionally provided in order to store bottom liquid 12 from the high pressure stage 10. In case of increased oxygen production, the internal rate of flow in the high pressure stage 10 can be raised; and simultaneously the internal rate of flow in the low pressure stage 11 and the reflux ratios in both rectifying stages 10, 11 can be maintained constant. The constant reflux ratio in the low pressure column permits the argon bubble concentration to remain high, permitting a substantially maximum rate of separation of the argon in a crude argon column.

Low temperature air fractionation accommodating variable oxygen demand

A process and apparatus for air separation by low temperature rectification are described in which argon is obtained exclusively by rectification. A crude argon column (24) is equipped with at least 150 theoretical plates in the form of low pressure drop packing so that, in it, a substantially complete separation of the oxygen is possible, e.g., less than about 10 ppm, preferably less than 1 ppm oxygen.

Argon purification

A process is disclosed for producing gaseous crude argon by low-temperature rectification of air wherein a portion of the compressed air is further compressed. The further compressed air is partially liquefied by countercurrent heat exchange with evaporating crude argon obtained in the liquid phase, this crude argon being under elevated pressure.

Process for the production of crude argon

A space and energy saving adsorber unit comprising two adsorber beds arranged in a common housing. The upper adsorber bed, disposed essentially vertically, is contained by gas permeable vertical walls, thereby permitting gas to be treated in the horizontal direction. The second adsorber bed, located beneath the first bed, slopes downwardly from an upper apex with increasing distance from a vertical central axis and is also enclosed, at least in part, by gas permeable walls. During regeneration of the system where water might be condensed in the bed, the condensate flows out of the bed without damaging the adsorbent.

Adsorber bed apparatus

Adsorbers are loaded with impurities removed from a compressed gas stream and are regenerated by a gas heated by the heat of compression of the gas stream. A heat reservoir or accumulator is employed instead of a conventional shell and tube type heat exchanger.

Process for regeneration of adsorbers

A process and apparatus for regenerating an adsorber through which alternatingly flows a raw gas and a regenerating gas. Adsorbent material is arranged within the adsorber and the ratio of the amount of raw gas to regenerating gas conducted over the adsorbent material adjacent the walls of the adsorber per unit area of adsorbent material is greater than the ratio of the amount of raw gas to regenerating gas conducted per unit area over the remaining adsorbent material. The amount of raw gas and regenerating gas conducted over the adsorbent material is adjusted and controlled by providing a bulkhead within the adsorber to separate the adsorbent material adjacent the adsorber wall from the remaining adsorbent material. Secondary feeding or discharge means is associated with the bulkhead area for regulating the flow of regenerating gas therethrough.

Process and apparatus for the regeneration of an adsorber

In the fractionation of a gaseous mixture, e.g., air, by rectification, wherein liquid in the sump of a rectifying column is heated and thereby partially vaporized; and simultaneously sump liquid is withdrawn from a lower zone of the sump liquid bath, and is recycled into the bath above the point of withdrawal, the improvement, prior to the recycle step, of passing the withdrawn sump liquid from the lower zone into a heat exchanger disposed in the sump, said heat exchanger having a substantially sealed bottom end at a level below the liquid level of the sump, and an open top end at a level higher than the liquid level of the sump; said withdrawn sump liquid being passed into the bottom end of said heat exchanger and partially vaporized therein, and removing resultant liquid-vapor mixture from the heat exchanger at the top end above the level of the liquid bath. This system provides pump-free circulation of the sump liquid and the use incorporates an on-line adsorber to remove deleterious impurities from the sump liquid, e.g., hydrocarbons from oxygen.

Continuous system of rectification

In a process for the low-temperature separation of air into dry product gases wherein at least a portion of the entering air is cooled by indirect heat exchange in a heat exchanger against at least one of the product gases and is freed of impurities by an adsorption process prior to this heat exchange, the improvement which comprises freeing the air of substantially only H.sub.2 O in the adsorption process and periodically interchanging the flow paths for the air and for the product gas, respectively, in the heat-exchanger.

Process and apparatus for the low-temperature separation of air

In an adsorption process for the separation of gases, e.g., in the separation of CO.sub.2 and H.sub.2 O from air, wherein gas to be separated is passed through one of several interchangeably connected adsorbers, and a main stream of regenerating gas is passed in two periods through another of said interchangeably connected adsorbers, the first period being a heating period to desorb the adsorbent, and the second period being a cooling period to cool the adsorbent to adsorption temperatures, During the cooling period, branching a partial stream of regenerating gas from the main stream, heating the partial stream with the means, and passing resultant heated partial stream over a heat accumulator, and during the heating period, passing the main stream of regenerating gas across said heat accumulator to recover the heat stored in the accumulator during the cooling period, and then further heating the main stream with the heating means to heating period regeneration temperatures.

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Munich, Germany

Wilhelm Rohde