JPS60260411A - Method and device for separating krypton from krypton/nitrogen-gas mixture through adsorption - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application - The present invention relates to a method for the separation of krypton by adsorption from gaseous combinations containing, in addition to krypton, in particular nitrogen, in an adsorption column.

Prior art adsorption columns are filled with an adsorbent that adsorbs krypton and nitrogen over a length L extending in the direction of the incoming gas mixture. After the gaseous components have been adsorbed in the adsorption column, the adsorbent is desorbed in the next process step by means of a gaseous cleaning agent. This cleaning agent flows through the adsorption column in the same direction in which the gas mixture was introduced into the adsorption column in the first process stage.

Krypton is separated from the gas mixture from the waste gas generated from the nuclear fuel reprocessing plant in the combustion tower, since the krypton isotope Kr-85, which is generated during the reprocessing of nuclear fuel, is radioactive. There is a need. The krypton isotope Kr-85 is a β-radiation source with a half-life of 10.7 years and is contained in the krypton isotope mixture with a proportion tV of 7% by volume. For krypton as a noble gas, only physical separation processes are applicable, and among these separation processes, the adsorption of krypton with adsorbents such as activated carbon or molecular sieves is reliable and reliable in its working mode. It is particularly suitable for the reprocessing of nuclear fuel. Nuclear fuel reprocessing involves hot-cape technology, i.e., work in a space that is shielded from the generation of radioactive sources and where the work steps are carried out remotely or via manipulators. is necessary. Efforts have therefore been made to simplify the operation of adsorption plants.

in waste gases generated from reprocessing plants.

In addition to krypton and nitrogen, there is also NO! as a component of the air introduced into the regeneration treatment plant! .

Aerosol contains gaseous components such as iodine, water vapor and oxygen. Therefore, before separating the krypton, the waste gas is pre-purified, first of all the NOx components, aerosol and iodine, then of the residual NOx, water vapor and finally of the Kg? Senon was separated and died. Residual waste gas is approximately 0
．． It contains a proportion of 1% by volume of krypton and essentially 80% by volume of nitrogen. In order to reduce the residual volume to be stored as much as possible, the krypton must be sufficiently isolated from this waste gas mixture. The total impurity proportion of the krypton to be stored - for example due to nitrogen, oxygen, quinanone - must be less than 10% by volume. □ From German Patent Publication No. 2,210,264 on the separation of krypton by adsorption, using an adsorption column which is not filled with activated carbon and which is loaded with krypton until the krypton is destroyed. It is known. The adsorbed krypton is recovered from the adsorption column by a combination of low pressure desorption and cleaning gas desorption.

The disadvantages of this method are, on the one hand, that it requires a long pumping phase for desorption and, on the other hand, during the desorption of the column for krypton in the cleaning gas. The enrichment factor achieved is relatively small.

A similar separation method applying adsorption and desorption during temperature and pressure alternations is described in German Offical Application No. 2,655.
．． ? Known from No. 56. In this process, of course, the noble gas is precipitated together with krypton and xenon in the adsorption column.

From German Published Patent Application No. 2,526,060, the entire adsorption chamber through which the adsorbent waste gas flows and is cooled is moved, and subsequently the heated and adsorbed gas components are released. A method for continuously separating krypton by moving the desorption chamber is known.The adsorbed rare gases krypton and medium senone are separated by purification adsorption.In this method, 1M What you get m
The rate is highly dependent on the adsorption properties of the adsorbent.

International patent application filed, l DE 30 49 761 A
Other adsorption methods, such as those described in the patent application No. 1 and published by the German Patent Office of the Federal Republic of Germany, are also costly. In this process, first the mesocenone, then the oxygen and subsequently the krypton are separated from the waste gas in successive process stages, each with at least two adsorption columns, so that the adsorption stage is separated from the waste gas. At the end, pure nitrogen remains. In this method, the K to be applied is exclusively partially made using a special gi nine-molecular sieve.

A high enrichment of krypton in the gas mixture to be purified and its separation using a gas chromatograph is known from DE 32 14 825 A1. In this case, efforts are being made to contain the amount of krypton contained in the waste gas.

Problems to be Solved by the Invention The problem to be solved by the present invention is to provide gases other than krypton, which can achieve high separation efficiency in a simple process and also allow most of the entire gas separation process to be carried out outside the hot cup. i! There is a rounded method of separating krypton from a gas mixture containing it.

Means for solving the problem tX This problem is solved according to the invention in a manner in the manner described at the outset and by the features described in claim 1.

The loading of the gas mixture into the working adsorption column takes place as follows. That is, the adsorbent is only partially loaded with krypton, and taking into account the transfer rate of the adsorbed krypton and nitrogen during desorption of the adsorption column with cleaning gas, first only the nitrogen is loaded, and later the krypton is loaded onto the adsorption column. The above-mentioned loading is carried out in such a way that it can be removed from the gas outlet. The rate of movement of the adsorbed material depends essentially on the temperature of the adsorbent, its type and the velocity of the cleaning gas. The value vKr<vN is obtained for the migration rate of krypton vKr and nitrogen VN in the adsorbent. That is, during desorption, nitrogen flows through the adsorption column at a faster rate than krypton. Given this difference in travel speeds, for an adsorption column filled with adsorbent over a length L seen in the direction of flow of the gas mixture or cleaning gas as described at the outset:
Maximum loading capacity with krypton is possible over a partial length Lo dimensioned such that nitrogen has already left the adsorption column before krypton appears at the outlet. This partial length Lo is determined empirically.

At that time, the adsorbent in the adsorption column becomes partially lengthened.

It was loaded with Krypton and pulled 1! If subsequently desorbed by the cleaning gas, all the nitrogen that was first adsorbed together with the cleaning gas at the end of the adsorption column, followed by the krypton with the cleaning gas, flows out.

Allowable partial length by krypton. Loading of the adsorption column up to this point is advantageously carried out by filling the adsorption column with the gas mixture with the gas outlet closed and increasing the pressure to a predetermined gas pressure. After a predetermined gas pressure is reached, the supply of the gas mixture is stopped, and cleaning is then performed by opening the ninth gas outlet for desorbing the adsorbed gas components.

In this case, from the gas outlet first the cleaning gas is fed together with nitrogen into the nitrogen line and then with the cleaning gas scriptone into the krypton line (see claim 2). The maximum adjustable gas pressure of the gas mixture when loading the adsorption column can be determined empirically by the maximum loading capacity of the adsorption column with krypton at partial length Lo. If it is not possible to generate the maximum gas pressure/force required to fill the adsorption column due to the limit conditions considered in industrial practice, the adsorption can be increased by partially opening the gas outlet. A predetermined length of the adsorption column by krypton. A gas mixture is introduced into the adsorption column in such an amount that it is loaded up to 100%. The loading of the adsorption column in the above method by adjusting the predetermined gas pressure can advantageously be carried out at room temperature (see claim 5). Increase the flow rate of waste gas,
and in reducing the helium flow through, this is achieved by cooling the adsorption column during the loading phase (see claim 4). The adsorption column is desorbed at a lower gas pressure than the gas pressure under load. It is advantageous to unload the suction column at atmospheric pressure (see claim 5).
(see section). In this case it is possible to carry out the work at room temperature. Rapid desorption is achieved by heating the adsorbent.

Suitable cleaning gases are inert gases or other suitable gases which do not chemically react with the components of the gas mixture. It is advantageous to desorb the adsorption column with helium (see item 6 of the fF tolerance requirements).

This is because helium and krypton can be easily separated from each other by, for example, freezing krypton.

In order to save the effort of completely cleaning and removing the adsorbed krypton before recharging the adsorption column with the gas mixture to be separated, the arrangement of claim 7 provides a method for newly loading the adsorption column with the gas mixture to be separated. When loading the adsorption column, the gas head and the gas outlet are reversed with respect to each other, so that the newly supplied gas mixture in each case is replaced by the previously adsorbed cleaning gas/krypton mixture. At the point where it is taken out, it flows into the adsorption column. In this way, the krypton that is still present after desorption in this location of the adsorption column is removed at the beginning of the next separation step.

A suction cup 2,000 with the following characteristics is suitable for carrying out the method according to the invention.

Known values: vKx = migration roughness of krypton during desorption with cleaning gas, vN = migration rate of nitrogen during desorption with cleaning gas.

L, = length of the part of the adsorption column that is loaded with krypton with the gas outlet of the adsorption column closed, depends on the gas pressure, type of adsorbent, and temperature. The following calculations are obtained for the length L of the adsorption column: OL ≧ □ ”IN to increase the adsorption capacity of the adsorbent and to reduce the capacity of the adsorption stage, and to reduce the wash flow. , and rounding to reduce the overall hot cape space used to separate xenon and krypton. According to claim 8, the adsorption capacity of the adsorbent is exploited at low temperatures.

The rounded first adsorption stage retaining xenon is cooled to a temperature of -150°C and the second rounded adsorption stage retaining krypton is adjusted to a temperature in the temperature range of -150°C to -180°C. The first adsorption stage temperature of 130°C is the lowest temperature for xenon adsorption.
This is because, below the above-mentioned temperature, the simultaneous adsorption (co-adsorption) of krypton in the first adsorption stage becomes so significant that the desired xenon-krypton separation is deteriorated. This is because, after heating the adsorption stage, the adsorbed xenon is significantly contaminated by krypton. The adjustable low temperature of the rounding in the krypton conduit in the second adsorption column depends on the proportion of oxygen in the mixture. At the same time, the adsorbed oxygen weakens the adsorption capacity for krypton.

The lower the content of oxygen in the mixture.

The temperature tl can be selected lower and lower, and the adsorbent can be utilized with increasing adsorption capacity. The first adsorption stage is only partially loaded with xenon and the second adsorption stage is partially loaded with krypton, so that a separation between the air component, krypton and xenon is achieved during desorption. For desorption, according to the invention both adsorption columns are heated in stages with a detergent supply. In this case, one important thing for the first heating section is the desorption temperature! 2! The different transfer temperatures of the gas components, krypton and xenon, are determined in mutual proportions in the adsorbent such that first the air component desorbed at the gas outlet of the second adsorption stage and subsequently the highly enriched krypton can be extracted. It is to be. Once the krypton appears at the gas outlet, both adsorption stages are heated further, with xenon finally leaving the second adsorption stage after the krypton has been removed. 80℃ to desorb xenon
It is advantageous to apply all of the above temperatures.

The optimal process configuration for separating krypton from gas mixtures consists in desorption, in which the temperature in the first adsorption column is lowered to no higher than -20°C until the krypton is destroyed, and in the second adsorption column. This can be achieved in 9 cases by adjusting the temperature of 150°C to no higher than 150°C (see claim 9).

At this temperature level, it is possible to remove only very slightly contaminated krypton from the gas outlet of the second adsorption column after nitrogen and oxygen have been completely desorbed.

According to the structure set forth in claim 10.

If the heating rate at the gas outlet of the second adsorption stage until the krypton is destroyed is adjusted such that a malformed temperature profile develops in the adsorbent, the extremely Uniform attachment and detachment takes place.

An economical process embodiment is achieved by using in the adsorption phase the purified gas mixture exiting from the gas outlet of the second adsorption stage as cooling agent for the rounding of the first adsorption stage (see claim 1). (See item 11). Only the second adsorption stage is then cooled to the adsorption temperature with a coolant such as liquid nitrogen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will now be explained in detail with reference to embodiments illustrated in the accompanying drawings.

FIG. 1 shows the necessary operating circuit for an adsorption column 1 for krypton separation, to which a xenon separation section 2 is connected upstream.

In this example, the xenon separation is also carried out (by adsorption). Activated carbon is used as an adsorbent. The adsorbent in the xenon separation section can be cooled to a temperature below room temperature in the adsorption phase by the cooling section 3. To accelerate the desorption, it is possible to connect a heating section 4 for heating the adsorbent.

A membrane pump 5 supplies the gas mixture to be purified, which contains approximately xenon and krypton components with a small proportion of nitrogen, to the xenon separation section. Membrane pump 5. The xenon separation section 2 and the adsorption column 1 are connected one after the other in the flow direction of the gas mixture via a supply 6 for the gas mixture. In the feed section 6, between the membrane pump 5 and the xenon separation section 2, a switchable three-way valve 7 is provided, via which the gas mixture to be purified is replaced. Helium is used as a cleaning gas for xenon adsorption and desorption in the xenon separation unit 2 through the purification gas conduit 8.
It can be introduced from When the xenon separation section 2 is attached and detached, a three-way valve 9 inserted behind the xenon separation section in the supply section 6 allows the cleaning gas containing the detached xenon to pass through the xenon guide v1o- into a liquid. The flow is switched to a cooling trap 11 with a cooling bath 12 filled with nitrogen. In the cooling trap 11, the xenon ore is again separated from the cleaning gas. The xenon-free cleaning gas is returned from the outlet of the cold trap 116 to the cleaning gas conduit 8 via the circulation system. The obtained xenon is stored in a suitable storage section 13.

An agricultural pump 14, which in this embodiment is inserted into the cleaning gas line 8, serves as the cleaning gas circulation system.

The adsorption column, through which the gas mixture to be purified after the xenon separation flows and through which the krypton is retained, is filled with activated carbon as adsorbent. In place of this activated carbon, a mustard sieve or zeolite can also be used. A shutoff cock 16 can be connected to the outlet 15 of one suction column in order to load the suction column 1 with 1 ton. In this embodiment, this shutoff; the plug 16 is connected to the outlet pipe 17
It is open inward. The load on suction column 1 is cut off cock 1
6 is closed and under increased pressure. The final pressure in the adsorption column is such that when the next desorption takes place, at the outlet 15 of the adsorption column, the cleaning gas with nitrogen is first
The selection is such that the cleaning gas with the krypton subsequently escapes. This process is shown in Figures 2 and 3 below.
This is explained in detail in the figure.

The adsorption column 1 can be desorbed in the same manner as the xenon separation section 2 with helium as a cleaning gas. For this purpose, a further three-way valve 18 is provided in the feed section 6 upstream of the adsorption column 1 and downstream of the three-way valve 9 in the flow direction of the gas mixture), this three-way valve 18 Helium is introduced into the adsorption column 1 from the cleaning gas conduit qft9. After the adsorption working phase, a cleaning gas is introduced into the adsorption column. 7. The previously aspirated cleaning gas-nitrogen mixture is transferred to the three-way valve 2.
0 and a connecting conduit 21 into a gas purification device 22, from which nitrogen and purified helium are separated from each other by suction. The nitrogen is led off through the nitrogen conduit 23 and the recovered helium is returned into the cleaning conduit 19 for use again as cleaning gas. An exchange pump 24 inserted into the cleaning gas conduit 19 serves to circulate the cleaning gas.

A cleaning gas/krypton mixture flows out of the adsorption column 1 following the cleaning gas/nitrogen mixture. Just before this mixture reaches the three-way valve 20 via the discharge conduit 17, the two three-way valves are switched. Then the cleaning gas - krypton -
It flows into a mixing vessel 26 in which the kryptic acid vessel is separated from the cleaning gas by cooling in a liquid nitrogen bath 27. The helium recovered from the i1C separation of krypton is also returned to the cleaning gas circulation system. For this step, a return conduit 28 is used, through which the helium is conveyed via the membrane pump 24 into the cleaning gas conduit 19. A shutoff cock 29 is mounted in the return conduit 28 and is opened when purified cleaning gas is removed from the storage container 26.

FIG. 2 shows the suction column 1 - 2e in this example.
With a column diameter of IIN, and 5030J[L
Kwa * two C'a adhesive. The progress of the krypton load in a field filled with activated carbon is shown. From Figure 2, it can be seen that the suction column is heavily loaded with krypton in a serrated manner over its entire length L (indicated by the horizontal axis in the Deitzkulam according to Figure 2), and the krypton is absorbed approximately half the length L of the suction column. In other words, it is observed that the length LO of 25t0M is absorbed.

In order to be able to ascertain the amount of adsorbed krybton in the adsorption column length units a, +, a, 0.6 milli cucurbits of krypton-85 per gas mixture era is added to the gas mixture to be purified. . The amount of chlorine retained by the adsorbent is detected by a radiation measuring device, for example, by guiding this device by applying oil to the outer wall surface of the adsorption column 1. The multi-count rate is measured in pulses per second (I P8 ) by a radiation measuring device.

This counting rate is shown in FIG. 2 by a vertical line in the diagram.

The adsorption column 1 is charged with krypton together with the gas to be purified under increased pressure with the shutoff cock 16 open. The incoming gas mixture essentially contains gold elements with a krypton content of 0.1% by volume. The IR2 diagram shows that the adsorption column is fully loaded with krypton, as already mentioned, at a temperature of 22 C and a pressure of 4.5 bar. This load on the adsorption column is then removed by adsorption column 1 when desorbed with helium as the purge gas.
The separation of nitrogen and krypton at the outlet 15 is made possible. The separation achieved is shown chromatographically in FIG.

For unloading and adsorption, the adsorption column is kept under normal pressure, i.e. atmospheric pressure (
Atm ) pressure and then flushed with helium. Figure 3 plots the proportions of nitrogen and krypton in the cleaning gas over the cleaning duration. In the chromatogram, the cleaning duration in minutes (min) is plotted on the horizontal axis.
The vertical axis shows the M element ratio and the krypton ratio in vpm (capacity ratio per 106i).

From FIG. 5, it can be seen that initially only nitrogen is removed from the adsorption column 1 with the cleaning gas, and then only after a cleaning duration of approximately 10 minutes' does the adsorbed krypton become present in the cleaning gas. The krypton content in the cleaning gas rises continuously to a content of about 2500 vqm after a cleaning duration of about 50 minutes, and then again after a cleaning duration of about 45 minutes in total.
It descends to vpIIl.

Therefore, the three-way valve 20 provided at the end of the discharge conduit 17
Cleaning gas containing krypton is transferred to krypton conduit 2.
5 and into the storage container 26 after a cleaning duration of 10 minutes. To maintain the necessary pressure gradient for this process, the K11l pump 24 is activated after the isolation cock 29 is opened. The adsorption column 1 is desorbed after a cleaning duration of approximately 45 minutes. That is, after this time the suction column is again ready for loading. The working cycle of the adsorption and desorption steps of the adsorption column is approximately 2 hours in this example.

Control of the flow rate of the gas mixture to be purified in the adsorption column can be achieved by increasing the pressure in the adsorption working phase.

Furthermore, it is possible to raise the temperature of krypton 1 adsorbed by the adsorbent to below room temperature by actually cooling the adsorbent.

FIG. 4 shows a ground t diagram for continuous krypton separation of Pi. The plant is equipped with two adsorption columns 1*, lb, which are filled with activated carbon in a manner similar to the embodiment illustrated in FIG. The adsorption columns 1a and 1b are operated alternately,
In this case, within the time that an adsorption column is loaded with krypton, the other adsorption column is desorbed with cleaning gas.

A gas mixture which is free of xenon and which, in addition to nitrogen, contains a small amount of krypton flows into the plant via feed 50 . The xenon separation section, which may be necessary for the gas to be purified and is located at the front of the plant, is not shown in FIG.

A three-way valve 51 is provided at the end of the feed section 30, which is connected to the conduits 52a, 32b, via which the gas mixture to be purified is can be introduced into the adsorption column 1a or into the adsorption column 1b. Conduit 62a.

Three-way valves 33a, 33b are present within 52b, both three-way valves being the cleaning gas conduit 34a.

5abK is connected to guide helium as a cleaning gas for adsorption and desorption of the adsorption columns 1a and 1b.

Adsorption columns 1a and 1b each have a switching valve 35a.

35b. These switching valves serve to alternately load the suction columns from their different ends. In FIG. 4, the switching valve 35a is shown in the valve operating state. The gas mixture present at this valve and to be purified is transferred to the adsorption column 1 via the adsorption column connection 36a.
introduced into a. The shutoff cock 57a in the discharge outlet 58a remains closed while the gas mixture is being introduced. Once the adsorption column is filled with krypton, the three-way valve 53aid is switched off, while the switching valve 55 is switched off.
In valve position 1, helium is still introduced into the adsorption column 1a as a cleaning gas via the adsorption column connection 36a't. In this case, the shutoff cock j7a is closed,
Desorbed gaseous components within the helium are exhausted via exhaust conduit 58a. When the suction column 1a is empty, the switching valve 351L is rotated to the one position where the switching valve 35b is located in FIG. When the adsorption column 1a is now loaded anew, the gas mixture to be purified from krypton flows into the adsorption column 1a from the other end via the adsorption column connection 39a. In this case too, the cutoff cock is 37! L
remains closed.

This alternating operation of the adsorption columns - on the one hand, the filling of the purge gas through the adsorption column connections 56eh;
2゜Cleaned crab. On the other hand, the desorption takes place together with the waste components via the adsorption column connection 59a; on the other hand, the loading of the adsorption column with cleaning gas takes place via the adsorption column connection 59a, and on the other hand the loading of the adsorption column with cleaning gas takes place via the adsorption column connection 56at. Discharge of cleaning gas containing desorbed gas components
has the following yfu points:

That is, after the adsorption column has been desorbed, the krypton-residue that may still remain in the adsorption column is likely to flow out first during the next adsorption/desorption cycle when desorption takes place. The helium/nitrogen mixture is not activated, but rather is discharged together with the helium/crypto-sea gas mixture that is subsequently discharged. This krypton-residue remains in the adsorbent in the vicinity of the outlet of the adsorption column each time a desorption step is carried out, and therefore remains within the area of the adsorption column where the krypton is adsorbed in the next adsorption operation/phase. exist. This alternating operation of the adsorption column reduces the demands placed on the purity of the adsorption column after desorption.

In order to separate the krypton and the phonemes, the exhaust conduit A8a opens into the three-way valve 40a, through which the cleaning gas loaded with nitrogen via the conduits 41a and 42 enters the gas cleaning system. [The cleaning gas guided into the krypton conduit 4 and loaded with xenon after switching
4a and 45. A membrane pump 46 is provided in the krypton conduit 45 by means of which a cleaning gas loaded with krypton is sucked from the adsorption column. Krypton is charged into reservoir 47 in the same manner as in the embodiment illustrated in FIG. The storage vessel 47 is cooled in a bath 48 filled with liquid nitrogen such that the krypton condenses within the storage vessel. The helium, which remains in gaseous form in this case, is returned to the cleaning gas circulation via the return conduit 49.

The membrane pump 5o works to maintain the cleaning gas circulation system.

Helium recovered within this membrane pump nitrogen gas purification device 43 is also sucked. For this purpose, the membrane pump 50 is connected to a helium line 51 leading from the gas purification device and opening into the return line 49.

In this embodiment, the gas purification device 43 is cooled with liquid nitrogen. The nitrogen which is separated from the helium/trephine mixture as condensate in this case is led off via nitrogen line 52.

While the desorption phase of the adsorption column 1a is being carried out, adsorption takes place in the adsorption column 1b for a further nitrogen/krypton gas mixture flowing in through the feed section 30. During the inflow of the gas mixture to be purified, the shutoff cock 57b, which is provided in the discharge conduit 38b as well as in respect of the adsorption column 1a, is closed.

In the position of the switching valve 55b shown in FIG. m4, the gas mixture to be metered flows into the adsorption column 1b via the adsorption column connection 39b'i.

After the gas components of nitrogen and krypton are adsorbed by the adsorbent in the adsorption column, the three-way valve ssb inserted in the conduit 52b before the switching valve 55b is switched, and the shutoff cock is switched accordingly. 57b is open, when the gas component is guided from the purification gas conduit 54b as cleaning gas helium through the adsorption column 1bt-, the cleaning gas that guides only nitrogen together with itself first passes through the adsorption column connection part 56b. It flows out from the adsorption column 1b through this process. During this working phase, a three-way valve 40b at the end of the discharge conduit 38b is regulated in such a way that the helium/11 element mixture is guided via the conduit 41b into the conduit 42 K and thus into the gas purification device 45. has been done. Once the helium has flowed out of the outlet of the adsorption column 1b along with the desorbed krypton, the three-way valve 40b is switched and coupled to the krypton conduit 44b. The helium/krypton mixture is then pumped through the single membrane pump 46 and flows through the krypton conduit 45 to a storage vessel 47. In the storage container 47, the crystals are separated as already mentioned.

The operations in the plant illustrated in FIG. 4 are carried out in the same manner as the operations in the plant illustrated in FIG. In this case too, after the adsorption step, with the gas pressure in the adsorption column increased, the gas isolation cocks 57a, 37b are opened to start the desorption phase, first with nitrogen and then with the cleaning gas/nitrogen. - the mixture and then the cleaning gas/krypton mixture flow out of the adsorption column.

The plant according to FIG. 4 is operated in almost continuous operation. In this case, the adsorption column can be operated either in an adsorption or in a desorption process. Krypton and nitrogen are produced as chemical products. The cleaning helium is guided through the circulation system.

When using active reversion as adsorbent, the flow rate of helium as cleaning gas (the so-called void volume) at temperature and with respect to krypton and nitrogen is 10 shoulder/s for the filled cross-section of the adsorption column. tube velocity), VKr=5a
An average movement speed of n/s and vN2=103/s can be detected.

Regarding this value, the above relation gives N2 as a first estimate for the length of the suction column.

From FIG. 5 it can be seen that two adsorption process trains a, b are installed as a plant, which are arranged in parallel and are constructed in the same manner of construction. Equivalent structural elements of each of these adsorption process sequences are designated with similar reference numerals in FIG. In this case the reference signs refer to these structures li! Additional symbols a and b are used to characterize belonging to either one of the elementary adsorption process sequences. Structural elements of the illustrated apparatus which do not have the reference sign S suffix are located outside the rIIL application process columns a and bO mentioned above.

The structure of the adsorption process sequence will be explained below based on adsorption process sequence a. In the adsorption train, there are two adsorption stages through which the gas mixture flows one after the other, which in this example consist of two adsorption columns connected one after the other. 1 a r 2 a K.

However, in contrast to this configuration, the process is carried out in only one adsorption column, which allows different temperature adjustments in the partial stages. When using two separate adsorption/adsorption columns, the prepurified gas mixture leaving the first adsorption stage is intercooled before entering the second adsorption stage. For this purpose, the device shown by way of example includes a heat exchanger 5 for precooling the gas mixture upstream of each adsorption column 1a, 2a! L
, 4a are connected.

The gas conduit 5a fully connects the heat exchanger and the adsorption column. Through this gas line 5a, the gas mixture to be purified or the cleaning agent flows through the adsorption stage train in the same flow direction, in which case both substances are first passed through the heat exchanger 5a and the adsorption column 1a and then into the heat exchanger 4a. It flows through the adsorption column 2a.

The adsorption column and heat exchanger can be cooled with a coolant, in an embodiment with liquid nitrogen. This coolant flows in the jacket cavity of the adsorption column and in the heat exchanger, respectively, provided for this purpose. These jacket voids are referenced 6a, 7a, 8a, ? in the drawings. Tail shown in a. Jacket gaps 6a and 7a of coolant adsorption column 1a+2a
flow in cocurrent, - flow in countercurrent to the gas mixture or cleaning agent in the jacket cavities 9a, 9a of the heat exchangers 3a, 4a. For both adsorption columns, the coolant flows from the cooled storage vessel 10 via the central conduit 11 into the jacket cavity of the adsorption columns. Supply conduits 12a and 13a are connected to the central conduit 11 for the adsorption process sequence B, and these supply conduits open into the jacket 9 gaps 6a and 7a. From the adsorption column outlets 14a, 15a a coupling conduit 16a.

17a communicates with jacket cavities 1113a and 9a.

. These coupling conduits connect the gas outlets 1 of the heat exchangers 5a, 4a.
Jacket empty 11j in the area of 8a, 19a 8a, 9a
It is open inward. The coolant therefore flows through the heat exchanger only after it has cooled the adsorption column. The coolant is supplied to each heat exchanger 3-a.

It is discharged via coolant outlets 22a, 25a which are connected to gas inlets 20a, 21a of 4a.

Coolant outlet 22a in order to adapt the coolant flow to the desired temperature to be adjusted in the adsorption column.

Flow rate adjusting devices 24a and 25a are installed in 23a, and these flow rate adjusting devices are connected to temperature sensors 26a and 2.
It is operatively connected to 7a. A reference temperature for the actual temperature of the adsorbent in the adsorption column is determined by means of a temperature sensor located in the jacket area of the adsorption column.

The gas conduit 5a is connected to a three-way valve 28aK before the gas inlet 20a of the first heat exchanger 5a, and the gas mixture to be purified is passed through the three-way valve to both adsorption column process rows a and b.
or from the central gas mixture conduit 29 for the helium or from the likewise central cleaning agent conduit 30 (cleaning conduit 60') for the helium and the likewise central cleaning agent conduit 6 for the air.
0 (washing conduit sa') and alternatively adsorption column a,
It can be introduced into b.

The gas conduit 13a is connected to the gas outlet 15 of the 12 adsorption columns 2a.
From m, the gas flowing out from the adsorption stage a during the adsorption working phase or during desorption is allowed to flow off.

The gas line 31a can be connected via a valve system 32ai, which is shown only schematically in FIG. The cleaning agent flows through the krypton conduit and the xenon conduit along with the recovered krypton or xenon. Krypton and xenon are separated from the cleaning agent, for example by freezing. The equipment required for this process is not shown in the drawings. Both the air component recovered during adsorption and the air component separated as the first gas component during desorption are discharged via the waste gas conduit 35a.

The adsorption process trains a, b are operated alternatively, in each case one of the adsorption process trains being in the adsorption working phase and the other being in the spreading desorption working phase. 5 The separation of xenon and krypton from the gas mixture to be purified therefore takes place almost continuously.

In these embodiments, the adsorption column consists of a steel tube surrounded by a cooling jacket and filled with activated carbon as an adsorbent. The usual active translation is used in the Gasque Quadrigraph. Copper pipe is 5.5
It has an inner diameter d of cm and a length Lvc of 52 tM. The adsorption column is cooled with liquid nitrogen and has electric jacket heating sections 100a, 100b, 101a, 101.
It can be heated by b. The heat exchanger consists of double tubes, into which the liquid is introduced into an annular gap.

Air containing 0.1% by volume of xenon and 0.01% by volume of krypton is introduced into the adsorption column as a gas mixture. The temperature of the adsorbent in the first adsorption column is -150
C, the temperature in the second adsorption column B-t7ocKlt1
There is one verse. The gas flow rate in adsorption work is 90 standard cubic meters per hour. Since the adsorption column is loaded with xenon and krypton only over a partial length K, a separation of the gas components is achieved during desorption.

21! After a sub-m3 gas charge, the supply of gas mixture is stopped and the adsorption column is desorbed. In this case, cleaning is carried out with 91 liters of helium per minute until complete desorption of krypton has taken place, and then with air. In this case the adsorbent is heated. During the first desorption phase the heating rate was fractionated. 9! It is 5.5C. After a temperature of -25 G in the first adsorption column and a temperature of -65 C in the &2 adsorption column is reached, the electrical jacket heating is stopped. As the cleaning gas continues to flow further, bringing with it heat, the temperature of the adsorption column increases only slightly further. Immediately before krypton breaks down at the outlet of the second adsorption column, the temperature in the activated carbon in the first adsorption column reaches -201:[, and -50 filC in the activated carbon in the second adsorption column.

After complete desorption of krypton, cleaning is performed with air instead of helium. In this case, the temperature of the adsorption column is 120C
K is heated. For xenon desorption, an operating diagram of an adsorption/desorption working cycle has been illustrated already at approximately 80 C in an adsorption column. In the operating diagram, depending on the working time t/min, the temperature decrease (at temperature C) in the adsorbent of the adsorption column and the concentration of the gaseous components of the gas exiting from the gas outlet of the second adsorption column (# (volume % on a degree-logarithmic scale).

As is clear from this operating diagram, within two hours two standard cubic meters of the gas mixture (air; 0.1% by volume Xs; 0.01% by volume Kr) are in the adsorption working phase flowing through the adsorption column. About 80% nitrogen by volume and about 2
At the outlet of the second adsorption column, a gas mixture consisting of 0% by volume and 0% by volume is formed. The temperature "Im" 2a in the adsorption columns 1a, 2a during this adsorption working phase is, as already mentioned, %-1200 and -150C. From the beginning of the desorption phase, the phoneme and oxygen proportions in the flushing gas decrease. Flushing with helium takes place while the temperature gradually increases in the adsorption column. However, the temperature T
la ' T2a does not exceed -2 (Ic or -500'. If the krypton is destroyed at the gas outlet of the second adsorption column, the measurable concentrations of the air components - nitrogen and oxygen - are already extremely small. From the point of krypton destruction, the adsorption column (with a heating rate of 9.2 C/min in this example) is heated to a final temperature of 120 C. Once all the krypton has been desorbed, the helium wash is replaced by an air wash. Then, the adsorption column is cooled again to -120 C or -170 C by introducing liquid nitrogen, forming a closed working system. The total adsorption/desorption cycle lasts 4 hours.

First adsorption columns 1a, 1b and heat exchanger 5a+5bli
Instead of cooling with liquid nitrogen, the gas is discharged from the gas outlet of the second adsorption column 2m, 2b during the adsorption working phase. It is economical to use the purified air component as a coolant for the abovementioned units of the adsorption process sequence. The purified air is then introduced into the irradiation adsorption column and the heat exchanger via gas lines 55h, 55b.

[Brief explanation of drawings]

Figure 1 shows 70 sheets of the adsorption line for xenon and krypton separation. FIG. 2 shows the course of the krypton loading carried out over the length L of the sorption column according to FIG. Figure 3 shows the chromatograph during desorption of an adsorption column loaded with krypton and nitrogen according to Figure 1; Figure 4 shows a plant for the separation of krypton by alternative operation of a number of adsorption columns FIG. 5 is an operating diagram regarding the attachment/desorption work cycle for applying the method according to the present invention. Reference symbols in the figure are: 1...Adsorption column 2...Xenon separation section 3...Cooling Parts 5*, 5b...Heat exchanger agent Mitsuyoshi Ezaki agent Mitsushi Ezaki Subaru J Konshu Cod Darkness (珈) Continued from page 1 Priority claim 6 August 13, 1984 [phase] West Germany (
D E ) @P3429736. '. 0 Inventor Liorfgang Flo, Rimmeltonstrasse, Federal Republic of Germany, 46 @ Inventor Melt-Noin 1 Kose, Federal Republic of Germany, 43 0 Inventor Martin Messler Rimmeltonstrasse, Federal Republic of Germany Pusumi Issutsuhi, Arteitzreliestrarun, Farsanenweke, 7

Claims (1)

[Claims] 1. An adsorption column filled with an adsorbent for adsorbing krypton and nitrogen over a length L extending in the direction of the incoming gas mixture and which is gaseous after adsorption of the gas mixture. It is desorbed with a cleaning agent flowing in the same direction as the entire gas mixture. In a method for the adsorption separation of krypton from a gas mixture containing, in addition to krypton, in particular nitrogen, in an adsorption column, starting from the gas inlet of the adsorption column and separating them from each other during desorption of the adsorption column with a cleaning agent. The loading of the adsorbent with krypton is carried out only after a partial length LO of the total adsorption column length L, such that first only nitrogen and later krypton can be removed from the gas outlet of the adsorption column. shall be. Top□Power distribution method. 2 Load the suction door ram with a gas mixture with the gas outlet closed until a predetermined gas pressure is reached. □ After the predetermined gas pressure has been reached, the supply of the gas mixture is cut off and the adsorption column is subsequently cleaned in good condition with the gas outlet opened, in which case the cleaning gas flowing out from the gas outlet is transferred together with nitrogen into the nitrogen conduit. 2. A method as claimed in claim 1, in which cleaning gas is subsequently supplied together with krypton into the krypton conduit. 5. Load the adsorption column at room temperature. Claim 2
The method described in section. Tun Cool the adsorption column when loading it. A method according to claim 2. & A method according to any one of claims 1 to 4, wherein the adsorption column is desorbed at atmospheric pressure. & A method according to any one of claims 1 to 5, characterized in that helium is used as cleaning gas during desorption. 1. A method according to claim 1, characterized in that the gas inlets and outlets of the desorbed adsorption column are removed before it is reloaded. a. Two adsorption columns connected in series, the adsorbents of which can be cooled below room temperature for adsorption and heated for desorption; The adsorption column is filled with an adsorbent for adsorbing krypton and nitrogen over a length LK extending in the direction of the gas mixture and is gaseous after adsorption of the gas mixture. A method for the adsorption separation of krypton from a gas mixture containing, in addition to krypton, in particular nitrogen, in an adsorption column, which is desorbed with a cleaning agent, starting from the gas inlet of the adsorption column and desorbing with a cleaning agent. During the desorption of the adsorption columns, a partial length of the total adsorption column length L is obtained, such that it is possible to first take off only the nitrogen and later from the gas outlet of the entire krypton adsorption column, separately from each other. An apparatus for carrying out the method of full loading of adsorbent, characterized in that a heat exchanger for pre-cooling the gas mixture to be purified is connected in front of each adsorption column. . The above device. 9. In the same direction as the gas mixture, the adsorption column is made up of an adsorbent adsorbing krypton and nitrogen over a length extending in the direction of the incoming gas mixture and is gaseous after adsorption of the gas mixture. It is desorbed by the flowing cleaning agent. In a method for separating krypton by adsorption from a gas mixture containing, in addition to krypton, in particular nitrogen, in an adsorption column, xenon t is also added to the krypton in the first adsorption step membrane in the first adsorption step. As in the case of (1), the absorption Mk is carried out only over the partial length of the first adsorption stage from which xenon can be taken out during desorption;
and the adsorbent of the first adsorption stage to a temperature not lower than -130°C, and the adsorbent of the second adsorption stage t--15
cooling to a temperature in the temperature range between 0'C and 180'0 and heating the adsorbents of both adsorption stage stages stepwise under the supply of detergent for desorption, in this case below room temperature. First, the temperature stage is adjusted so that the gust component and krypton are separated and flowed out from the gas outlet of the second adsorption stage, and the I
In order to destroy krypton and desorb xenon after death at the outlet of the adsorption stage of R2, heating above room temperature is required. The above method. 1α Heating to a temperature not higher than the first adsorption stage '1-20'C until krypton is destroyed at the outlet of the second adsorption stage, and heating to a temperature not higher than -50 °C in the second adsorption stage 'i. 9. The method according to claim 8. 11. Adjust the heating rate for the adsorption stage to create a flat temperature profile within the adsorbent until the krypton is destroyed. ! A method according to claim 8 or 9. 12. Use of the purified gas mixture flowing out of the gas outlet of the second adsorption stage during the adsorption operation to cool the first adsorption stage; f Scope of Performance Request Items 8 to 1
The method described in any one of item 0. IS comprises two adsorption columns connected in series, the adsorbents in these adsorption columns being capable of being cooled to 1C below room temperature for adsorption and heating for desorption; over a length L extending in the direction of the incoming gas mixture, the gaseous,
It is desorbed with a cleaning agent flowing through the adsorption column in the same direction as the gas mixture. A method for separating krypton by total adsorption from a gas mixture containing nitrogen in addition to krypton in an adsorption column, in which total xenon is also removed first during adsorption.
As in the case of krypton in the second adsorption step, adsorption is carried out only over a partial length of the first adsorption step from which xenon can be removed during desorption, and The adsorbent of the 1st adsorption process stage is 113
The temperature is not lower than 0℃. And the adsorbent in the second adsorption stage is heated to -150℃--18℃.
cooling to a temperature in the temperature range between 0°C and heating the adsorbent in both stages of the adsorption process stepwise with the supply of cleaning agents for desorption, in which case the air components and krypton are first separated below room temperature. The temperature stage is adjusted so that the krypton is separated and flows out from the gas outlet of the second adsorption stage, and the xenon is desorbed after the krypton is destroyed at the exit of the second adsorption stage. In the apparatus for carrying out the method, a heat exchanger for precooling the gas mixture to be purified is connected upstream of each adsorption column, and f:! ! # sign. The above device.