DE10232430A1 - Process for recovering krypton and/or xenon comprises feeding a liquid from the lower region of a krypton-xenon enriching column to a condenser-vaporizer, and contacting an argon-enriched vapor with the liquid from the enriching column - Google Patents

Abstract

A liquid from the lower region of the krypton-xenon enriching column is fed to a second condenser-vaporizer, and a second argon-enriched vapor from the crude argon rectification columns is contacted with the liquid from the lower region of the krypton-xenon enriching column in the second condenser-vaporizer in direct heat exchange. Process for recovering krypton and/or xenon by the low temperature decomposition of air comprises feeding compressed purified process air (1) into a rectification system having a high pressure column (2) and a low pressure column (3) for nitrogen-oxygen separation, feeding the krypton- and xenon-containing fraction (13, 14, 15, 16) obtained from the high pressure column into a vaporization chamber of a first condenser-vaporizer (17) and partially vaporizing, removing a rinsing liquid from the vaporization chamber, feeding to a krypton-xenon enriching column (24), removing a krypton-xenon concentrate (30) from the column, feeding an argon-containing fraction (48) from the low pressure column into crude argon rectification columns (18, 19), and contacting a first argon-enriched vapor (50) from the crude argon rectification columns with the vaporized krypton- and xenon-containing fraction in the first condenser-vaporizer in direct heat exchange. A liquid from the lower region of the krypton-xenon enriching column is fed to a second condenser-vaporizer (27), and a second argon-enriched vapor (122) from the crude argon rectification columns is contacted with the liquid from the lower region of the krypton-xenon enriching column in the second condenser-vaporizer in direct heat exchange. An independent claim is also included for a device for carrying out the above process.

Description

The invention relates to a method according to the generic term of claim 1, for the extraction of krypton and / or xenon by low-temperature decomposition of air.

The basics of low temperature decomposition of Air in general and the construction of rectification systems for Nitrogen-oxygen separation in particular are in the monograph "Low Temperature Technology" by Hausen / Linde (2nd edition, 1985) and in an article by Latimer in Chemical Engineering Progress (Vol. 63, No.2, 1967, page 35). The High-pressure column becomes under a higher Pressure than the low pressure column operated; the two pillars are preferably in heat exchange relationship to each other, for example about a main condenser, in the top gas against the high pressure column evaporating swamp liquid the low pressure column liquefied becomes. The rectification system of the invention can be used as a classic double column system be designed, but also as a three or multi-column system. In addition to the columns for nitrogen-oxygen separation can be further Devices for extracting other air components, in particular of noble gases, for example argon extraction.

A method for obtaining krypton and / or xenon by low-temperature separation of air and a corresponding device are known DE 10000017 A1 known. Here, a krypton- and xenon-containing fraction, namely the sump liquid, is led from the high-pressure column of the double column for nitrogen-oxygen separation without concentration-changing measures into another column, which is used for krypton-xenon extraction.

DE 2605305 A shows a method and an apparatus for the extraction of krypton and / or xenon by low-temperature separation of air of the type mentioned. Here, the first condenser-evaporator is heated with condensing overhead gas from a crude argon column and at the same time represents the bottom heating of the krypton-xenon enrichment column Steam rising in the krypton-xenon enrichment column is generated in the first condenser-evaporator.

The unpublished German patent application 10153252 and the corresponding applications in other countries (for example European patent application No. 02001356) also show a method according to the preamble, in which a liquid is also introduced from the lower region of the krypton-xenon enrichment column into a second condenser-evaporator, which is separate from the first condenser-evaporator and is operated with pressurized nitrogen.

The invention is based, which To further improve krypton and xenon extraction and in particular to carry out in a particularly economical manner.

This task is solved in that a liquid from the bottom of the krypton-xenon enrichment column into one second condenser-evaporator is initiated by the first Condenser-evaporator is disconnected.

In the invention there is therefore a separate one Heat exchanger, the "second condenser-evaporator" provided in independent of that steam from the first condenser-evaporator is generated for the krypton-xenon enrichment column and thus a further concentration of less volatile Components is made. The second condenser evaporator is preferably designed as a sump heater for the krypton-xenon enrichment column. He can be inside this pillar or in a separate container be arranged and will with a second argon-enriched vapor operated from crude argon rectification, typically with steam from the head of crude argon rectification (from the head of a single crude argon or - in In case of a split crude argon rectification - from the head of the last one Raw argon columns, by which is also deducted from the raw argon product).

Through the second condenser-evaporator itself in the first condenser evaporator a less high oxygen concentration, so that the correspondingly reduced temperature difference the size of the first Condenser-evaporator can be reduced. Moreover there is less concentration of volatiles in the first condenser evaporator, which at this point is out of operational establish undesirable is.

The "rinse liquid" of the first condenser evaporator serves as a feed fraction of the krypton-xenon enrichment column. “Krypton-xenon enrichment column” is understood here to mean a countercurrent mass transfer column in which a fraction is generated which has a higher concentration of krypton and / or xenon than any of the use fractions of this column. For example, the krypton-xenon concentrate has a higher molar content of krypton and / or xenon than the "rinse liquid" that is fed into the krypton-xenon enrichment column. This column can be implemented, for example, as an exchange column as in DE 10000017 A1 and / or simultaneously serve to discharge methane.

The rinsing liquid is preferably introduced in the lower region, approximately immediately above the sump. In this case, a liquid is applied to the top of the krypton-xenon enrichment column in order to drive down the krypton present in the rising vapor and methane upwards ben. This liquid can be taken from the high-pressure column, for example, from its sump or some trays above. Possible alternative or additional sources are the evaporation space of the top condenser of a pure argon column. In the bottom of the krypton-xenon enrichment column, the liquid flowing down can be boiled by means of a bottom evaporator (in particular the "second condenser evaporator"). As a result, the krypton and xenon content of the krypton-xenon concentrate can be increased further.

In the invention between the Withdrawal of the krypton- and xenon-containing fraction from the high pressure column and an intermediate step in the feed into the krypton-xenon enrichment column Form of partial evaporation in the first condenser-evaporator performed. This step is used to concentrate Krypton and / or Xenon in front of the krypton-xenon enrichment column. As another effect also all other components that are more volatile than oxygen with the rinse from the partial evaporation into the krypton-xenon enrichment column and thus kept away from other system parts, especially the low pressure column.

The krypton-xenon concentrate, that generated in the krypton-xenon enrichment column has one Krypton content of, for example, 600 to 5000 ppm, preferably 1200 to 4000 ppm, a xenon content of, for example, 60 to 500 ppm, preferably 120 to 400 ppm. For the rest, it mainly consists of Oxygen and typically about 10 mol% nitrogen.

Crude argon rectification is used in particular for argon-oxygen separation and can be carried out in one or more columns (see for example EP 377117 B2 or EP 628777 B1 ).

The invention is part of a Air separation plant with argon extraction, one fraction containing argon from the low pressure column in a crude argon rectification is initiated. The cooling of the crude argon rectification, which is necessary anyway, is in the context of the invention partly through the krypton- and xenon-containing Fraction operated, according to the preamble an argon enriched vapor from crude argon rectification in the first condenser evaporator in indirect heat exchange occurs with the evaporating fraction containing krypton and xenon. The partial evaporation in the context of krypton-xenon extraction (first Condenser-evaporator) and the generation of rising steam for the Krypton-xenon enrichment column (second condenser-evaporator) are used for generation at the same time of return and / or liquid product in crude argon rectification.

• – Die Heizfläche für die Rohargonkühlung wird zwischen erstem und zweitem Kondensator-Verdampfer aufgeteilt. Der erste Kondensator-Verdampfer kann dadurch kleiner und damit kostengünstiger ausgeführt werden.
• – Das Rücklaufverhältnis in der Niederdrucksäule verbessert sich. Somit wird eine höhere Argonausbeute erzielt.

Compared to the use of pressurized nitrogen to heat the krypton-xenon enrichment column, the following advantages result:

• - The heating surface for crude argon cooling is divided between the first and second condenser evaporators. The first condenser-evaporator can thus be made smaller and therefore less expensive.
• - The reflux ratio in the low pressure column improves. A higher argon yield is thus achieved.

In many cases there is a liquid feed air flow available, for example when compressing one or more internally Products. Frequently the liquefied Air between high pressure column and low pressure column divided, for example by introducing it into a cup, the inside of the high pressure column is arranged and part of the liquid air from this cup removed again and led to the low pressure column. Within the scope of the invention is it convenient if an oxygen-containing liquid is withdrawn from the high pressure column instead and into the low pressure column introduced that comes from a second intermediate point, the one above the first intermediate point is arranged, at which the liquid feed air is introduced into the high pressure column. This ensures that this is in the liquid feed air contained krypton and xenon flows towards the sump of the high pressure column and not into the low pressure column where it is headed for the krypton-xenon production would be lost. In addition, other more volatile contaminants kept away from the main capacitor. The liquid air (or an oxygen-containing one Liquid more like Composition) that flows into the low pressure column is according to this Aspect of the invention by largely Krypton- and Xenon-free Reflux liquid the high pressure column educated.

This aspect of the invention is in to use any method with advantage, in which a fraction from the high pressure column a krypton-xenon extraction is supplied. Its application is not on methods and devices with partial evaporation of the krypton and xenon-containing fraction. The same applies to the corresponding further configurations.

The oxygen-containing liquid can upstream their job on the krypton-xenon enrichment column in one another condenser-evaporator, especially in a top condenser a pure argon column, partially evaporated.

Barrier trays can be arranged in the pressure column, with the krypton- and xenone-containing fraction being drawn off below the barrier trays and an oxygen-containing liquid being removed above the barrier bottoms. The oxygen-containing liquid is thus much poorer in krypton and xenon than the krypton- and xenon-containing fraction and can, for example, be fed directly into the low-pressure column and / or used to cool the top condenser of a pure argon column without losing significant amounts of krypton and xenon , The number of locks Soil is for example one to nine, preferably two to six (theoretical floors).

In addition to the rinsing liquid can be a gaseous Current from the evaporation space of the first condenser-evaporator deducted and also fed to the Krypton-Xenon enrichment column , for example in the same place as the rinsing liquid. This also becomes in the evaporated part of the krypton- and xenon-containing fraction Krypton still contained the Krypton-Xenon extraction supplied.

The invention also relates to a Device for extracting krypton and / or xenon by cryogenic decomposition of air according to claim 5th

The invention and further details The invention are described below with reference to the drawings schematically illustrated embodiments explained in more detail. in this connection demonstrate:

1 a first embodiment of the invention and

2 an embodiment with integration of krypton-xenon enrichment column and crude argon column and

3 and 4 other systems with a different arrangement of the pure argon column.

Via line 101 of 1 inflows compressed air (AIR). It is converted into a first air stream (direct air) 102 , a second air stream (turbine air) 103 and a third air flow (internal compression air) 104 divided up. The main heat exchanger has two parallel blocks in the exemplary embodiment 105a . 105b on. The first airflow 102 will be in both blocks 105a and 105b of the main heat exchanger cooled to about dew point and without further pressure-changing measures via the line 1 gaseous in the high pressure column 2 of a rectification system for nitrogen-oxygen separation. The rectification system for nitrogen-oxygen separation also has a low pressure column 3 and a main capacitor 4 on, which is designed in the example as a falling film evaporator. Gaseous nitrogen 6 from the head of the high pressure column becomes the condensation space of the main condenser 4 fed. The condensate formed there 7 is introduced into the high pressure column and partly used there as a return. Another part 106 becomes liquid from the high pressure column 2 taken and branched again at 107. A first branch stream of liquid nitrogen is in a subcooling countercurrent 10 hypothermic, via line 108 into a separator (phase separator) 109 initiated and finally via line 114 obtained as a liquid nitrogen product (LIN). Another branch stream 111 of liquid nitrogen from the top of the high pressure column 2 (or from the main capacitor 4 ) is in a pump 112 brought to a desired product pressure in the liquid state, in the main heat exchanger block 105a evaporated (or pseudo-evaporated in the case of supercritical pressure) and warmed to about ambient temperature and via line 113 dissipated as a gaseous pressure product (PGAN). The third air stream is used to evaporate the liquid nitrogen 104 that in a post-compressor 115 with aftercooler 116 was brought to a correspondingly high pressure.

Via line 9 impure liquid nitrogen some theoretical trays below the head from the high pressure column 2 taken, in countercooling countercurrent 10 hypothermic and via line 11 and throttle valve 12 the low pressure column 3 fed on the head.

The cold high-pressure air liquefied or supercritical as part of the internal compression 117 is over valve 118 and management 44 at least partly in liquid form in the high pressure column 2 throttled, at a "first intermediate point" some theoretical trays above the high-pressure column sump. A "second intermediate point", which in turn is located some theoretical floors above this first intermediate point, becomes an oxygen-containing liquid 45 withdrawn from the high pressure column, which has hardly more volatile components such as krypton and xenon. The countercurrent in the supercooling 10 cooled liquid 119 is partly via line 46 and throttle valve 47 into the low pressure column 3 fed. Another part 20 the supercooled oxygen-containing liquid 119 is in the evaporation space of a top condenser 21 a pure argon column 22 fed.

The oxygen-enriched sump liquid 13 the high pressure column 2 is also in the supercooling counterflow 10 cooled. The supercooled oxygen-enriched liquid 14 - 15 is in a pure argon vaporizer 63 cooled further and is finally piped 16 as a "krypton- and xenon-containing fraction" in the evaporation chamber of a "first condenser-evaporator" 17 initiated the top condenser of a crude argon rectification 18 / 19 represents.

The first condenser evaporator 17 is designed as a circulation evaporator, ie the evaporation chamber contains a liquid bath into which a heat exchanger block is at least partially, preferably (in deviation from the schematic representation in the drawing) completely immersed. Liquid is sucked in through the thermosiphon effect at the lower end of the evaporation passages. A mixture of vapor and undevaporated liquid emerges at its upper end, the latter flowing back into the liquid bath. In the first condenser evaporator 17 becomes the krypton and xenon-containing fraction 16 partially evaporated; for example 0.5 to 10 mol%, preferably 1 to 5 mol% of the liquid introduced 16 become fluid as a rinsing liquid 26 from the evaporation space of the first condenser-evaporator 17 deducted. As a result of this partial evaporation, the concentration of less volatile components, in particular krypton and xenon, in the liquid is increased and reduced in the vapor (in each case in comparison to the composition of the krypton- and xenon-containing fraction 16 ). The steam generated during partial evaporation is called a gaseous stream 25 from the evaporation space of the first condenser-evaporator 17 deducted. Remaining liquid is called "rinsing liquid" 26 removed from the liquid bath and the krypton-xenon enrichment column 24 fed directly above the swamp.

From the low pressure column 3 become impure nitrogen 33 in gas and oxygen 34 withdrawn at least partially in liquid form as products or residual gas. The gaseous impure nitrogen 33 is shared with Flashgas 110 from the separator 109 in the supercooling counterflow 10 and in the main heat exchanger 105a / 105b warmed up. The liquid oxygen 34 is divided into three parts. A first and a second part are initially managed together 35 and pump 36 promoted. The first part 37 flows to the evaporation space of the main condenser 4 and is partially evaporated there. The vapor-liquid mixture formed in the process 38 flows to the bottom of the low pressure column 3 back. Over the lines 39 and 40 the second part is drawn off as a liquid product (LOX), after partial subcooling in the subcooling countercurrent 10 ,

The third part 41 of liquid oxygen 34 from the bottom of the low pressure column 3 becomes - similar to liquid nitrogen 111 from the high pressure column - subjected to an internal compression by being in a pump 42 brought to the desired product pressure and via line 43 the main heat exchanger (block 105a ) flows in where it evaporates (or - in the case of supercritical product pressure - pseudo-evaporates) and is warmed to about ambient temperature. Eventually he will be on line 120 obtained as a gaseous oxygen pressure product. Evaporation and heating are in indirect heat exchange with the high pressure air flow 104 - 117 carried out.

Via an argon transfer line 48 becomes an argon-containing fraction from the low pressure column 3 into a raw argon rectification, which in the example is in two serially connected raw argon columns 18 and 19 is carried out (so-called split crude argon column). The argon-containing fraction 48 becomes the first column of crude argon 18 fed in gaseous form directly above the swamp. The rising vapor accumulates in argon. The top gas of the first column of crude argon 18 flows over line 49 on to the bottom of the second column of raw argon 19 ,

At the top of the second raw argon column 19 becomes gaseous raw argon 121 deducted. A first part of it, about 90%, is called "the first argon-enriched vapor" 50 in the liquefaction space of the first condenser-evaporator 17 initiated and condensed there for the most part. The liquid generated in the process 51 is used as the return liquid on the second crude argon column 19 given up. Another part, about 10%, of raw argon 121 forms the "second argon-enriched vapor" 122 and serves as a heating medium for the sump evaporator 27 the krypton-xenon enrichment column 24 ("second condenser evaporator"). In the second condenser evaporator 27 formed liquid flows over line 123 back to the top of the second column of raw argon 19 ,

The one in the swamp of the second raw argon column 19 resulting liquid 52 is by means of a pump 53 via line 54 to the head of the first column of raw argon 18 promoted. bottoms liquid 55 the first column of raw argon 18 flows over another pump 56 and management 57 into the low pressure column 3 back.

Raw argon remaining in gaseous form 58 from the liquefaction space of the first condenser-evaporator 17 is in the pure argon column 22 further disassembled, in particular freed from volatile components such as nitrogen.

Pure argon product (LAR) is on the pipes 59 and 60 subtracted in liquid form. Another part 61 the bottom liquid of the pure argon column 22 is in the pure argon evaporator mentioned above 63 with attached separation 62 evaporated and piped 64 as rising steam in the pure argon column 22 returned.

The head capacitor 21 The pure argon column is, as already described, by a supercooled liquid 20 cooled. From the vaporization space of the top condenser 21 become steam 66 and remaining liquid 65 deducted. The steam 66 is at a suitable intermediate point in the low pressure column 3 fed. The - practically krypton and xenon free - liquid 65 is on the krypton-xenon enrichment column 24 given up. In the liquefaction chamber of the top condenser 21 condenses head gas 67 the pure argon column 22 partially. Return liquid generated in the process 68 is placed on the pure argon column. residual steam 69 is blown off into the atmosphere.

in the crude argon-heated bottom evaporator described above ("second condenser evaporator") 27 steam is generated in addition to the gas 25 in the krypton-xenon enrichment column 24 rises. As already mentioned, the rinsing liquid is used as the return liquid 65 from the evaporator of the top condenser 21 the pure argon column 22 on the head of the krypton-xenon enrichment column 24 given up. The one from the bottom evaporator 27 rising steam and that via pipe 25 The gas introduced in the krypton-xenon enrichment column interacts with the liquid in countercurrent 65 who is poorer in krypton and xenon. This will make this compo nents washed into the swamp, whereas methane partly with the top gas 30 can be removed. The latter is used in the embodiment of the low pressure column 3 fed at a suitable intermediate point. From the swamp of the krypton-xenon enrichment column 24 becomes a krypton-xenon concentrate 30 Taken in liquid form (raw KrXe), which contains, for example, a krypton content of around 2400 ppm and a xenon content of around 200 ppm: the rest of the concentrate is made up 30 mainly from oxygen and still contains about 10 mol% nitrogen and hydrocarbons. The concentrate 30 can be stored in a liquid tank or can be directly used for further processing to obtain pure krypton and / or xenon.

2 does not differ from the sequence of process steps 1 , However, the arrangement of the krypton-xenon enrichment column 24 different. While in 1 as a separate container above the first column of raw argon 18 is attached, it is located in 2 between the first condenser-evaporator 17 and the mass transfer area of the second raw argon column 19 , Krypton-xenon enrichment column 24 and second raw argon column 19 to a certain extent form a double column with the second condenser-evaporator as the "main condenser". Because the krypton-xenon enrichment column and the raw argon columns 18 . 19 have a similar diameter, such an arrangement can be particularly favorable in terms of apparatus.

In the embodiments of the 1 and 2 are the krypton-xenon enrichment column 24 , the second raw argon column 19 and the pure argon column 22 and their capacitors 27 . 17 . 21 arranged so that the liquids 26 . 51 . 65 . 68 and 123 to flow to their destination solely because of the geodetic gradient. However, this arrangement is not always optimal for spatial reasons.

at 3 is the pure argon column 22 arranged lower than in 1 so that the liquid 65 must flow upwards. For this purpose, the evaporation space of the top condenser 21 the pure argon column 22 under slightly higher pressure than in 1 operated so that the rinsing liquid 65 is pressed into the krypton-xenon enrichment column due to the corresponding pressure drop. A corresponding pressure difference is in the gas line 66 through the control valve 294 maintained.

The pure argon column of the 4 is also lower than in 1 , However, there is no increased pressure in the evaporation space of the top condenser 21 needed because the rinsing liquid 465 from the top capacitor 21 the pure argon column 22 directly at an intermediate point 492 into the low pressure column 3 is initiated deeper than the capacitor 21 lies. The feed fluid 493 for the krypton-xenon enrichment column there is already upstream of the top condenser 21 from the liquid 20 branched over the lines 45 and 119 from the second intermediate point of the high pressure column 2 was subtracted. Another part of this liquid 20 flows into the evaporation space of the top condenser 21 the pure argon column 22 ,

The exemplary embodiments of the unpublished German patent application 10153252 and the corresponding applications in other countries (for example European patent application no. 02001356 ) are included here. Modified by the use of part of the crude argon from the top of the crude argon rectification as a heating means for the bottom evaporator of the krypton-xenon enrichment column, they represent embodiments of the invention.

In all embodiments of the invention, the main condenser can be used instead of the falling film evaporator shown in the drawings 4 a combination of falling film evaporator and circulation evaporator can be used, which are connected in series on the evaporation side. In this case, the invention can bring about a further advantage: the recirculation pump can do so because only an extremely small amount of less volatile constituents of the air gets into the low-pressure column 36 saved for the falling film evaporator.

In a "falling film evaporator" flows the fluid to be vaporized from top to bottom through the vaporization space and is partially evaporated. In a "circulation evaporator" (also called liquid bath evaporator) stands the heat exchanger block in a liquid bath of the fluid to be evaporated. This flows through the thermosiphon effect from the bottom up through the evaporation passages and occurs at the top as a two-phase mixture. The remaining liquid flows outside of the heat exchanger block in the liquid bath back. (With a circulation evaporator, the evaporation space can contain both the evaporation passages as well as the outside space the heat exchanger block include.)

Claims (5)

Process for the extraction of krypton and / or xenon by low-temperature separation of air, in which - compressed and purified feed air ( 1 ) is introduced into a rectification system for nitrogen-oxygen separation, which has at least one high-pressure column ( 2 ) and a low pressure column ( 3 ), whereby - the high pressure column ( 2 ) a krypton and xenon-containing fraction ( 13 . 14 . 15 . 16 ) is removed, - the krypton- and xenon-containing fraction ( 13 . 14 . 15 . 16 . 416 ) in the evaporation chamber of a first condenser evaporator ( 17 ) and partially evaporated there, - a rinsing liquid ( 26 ) from the evaporation space of the first condenser-evaporator ( 17 ) deducted and - a krypton-xenon enrichment column ( 24 ) is fed, - the krypton-xenon enrichment column ( 24 ) a krypton-xenon concentrate ( 30 ) is removed. - an argon-containing fraction ( 48 ) from the low pressure column ( 2 ) into a raw argon rectification ( 18 . 19 ) is introduced, - a first argon-enriched vapor ( 50 ) from crude argon rectification ( 18 . 19 ) in the first condenser-evaporator ( 17 ) in indirect heat exchange with the evaporating fraction containing krypton and xenon ( 16 ) occurs, characterized in that - a liquid from the lower region of the krypton-xenon enrichment column ( 24 ) in a second condenser evaporator ( 27 ) is initiated by the first condenser-evaporator ( 17 ) is separated and - a second argon-enriched vapor ( 122 ) from crude argon rectification ( 18 . 19 ) in the second condenser-evaporator ( 27 ) in indirect heat exchange with the liquid from the lower area of the krypton-xenon enrichment column ( 24 ) occurs. A method according to claim 1, characterized in that a partial stream ( 44 ) the feed air in the liquid state at a first intermediate point in the high pressure column ( 2 ) is fed in and an oxygen-containing liquid from a second intermediate point which is arranged above this first intermediate point ( 45 . 119 . 20 ) from the high pressure column ( 2 ) deducted and at least partially ( 65 . 493 ) on the krypton-xenon enrichment column ( 24 ) is abandoned. A method according to claim 2, characterized in that the oxygen-containing liquid ( 45 . 119 . 20 ) upstream of their task ( 65 ) on the krypton-xenon enrichment column ( 24 ) in a further condenser-evaporator, in particular in a top condenser ( 21 ) a pure argon column ( 22 ) is partially evaporated. Method according to one of claims 1 to 3, characterized in that a gaseous stream ( 25 ) from the evaporation space of the first condenser-evaporator ( 17 ) and the krypton-xenon enrichment column ( 24 ) is fed. Device for the extraction of krypton and / or xenon by low-temperature separation of air, with - a feed air line ( 1 ) for introducing compressed and pre-cleaned feed air into a rectification system for nitrogen-oxygen separation, which has at least one high-pressure column ( 2 ) and a low pressure column ( 3 ), - with a sampling line ( 13 . 14 . 15 . 16 ) to remove a krypton- and xenon-containing fraction from the high pressure column ( 2 ), whereby - the sampling line ( 13 . 14 . 15 . 16 ) for the krypton- and xenon-containing fraction with the evaporation chamber of a first condenser-evaporator ( 17 ) is connected, - a flushing liquid line ( 26 . 226 ) with the evaporation chamber of the condenser-evaporator ( 17 ) and with a krypton-xenon enrichment column ( 24 ) is connected - the krypton-xenon enrichment column ( 24 ) a product manager ( 30 ) for a krypton-xenon concentrate, - a crude argon rectification ( 18 . 19 ) which are in flow connection with the low pressure column ( 2 ), - means for introducing a first argon-enriched vapor ( 50 ) from crude argon rectification ( 18 . 19 ) in the liquefaction chamber of the first condenser-evaporator ( 17 ), characterized by - a second condenser-evaporator ( 27 ) from the first condenser-evaporator ( 17 ) is separated and its evaporation chamber is in flow connection with the lower region of the krypton-xenon enrichment column ( 24 ) stands and - means for introducing a second argon-enriched vapor ( 122 ) from crude argon rectification ( 18 . 19 ) in the liquefaction chamber of the second condenser evaporator ( 27 ).