Process and installation for processing a krypton-, xenon-, methane-, and oxygen-containing feed mixture
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- LINDE AG
- Filing Date
- 2025-12-18
- Publication Date
- 2026-07-30
Smart Images
Figure EP2025087927_30072026_PF_FP_ABST
Abstract
Description
[0001] P04327-EP
[0002] December 9, 2025 - Imhof
[0003] 1
[0004] Description
[0005] Method and plant for processing a feed mixture containing krypton, xenon, methane and oxygen
[0006] The present disclosure relates to a process and a plant for processing a feed mixture containing krypton, xenon, methane and oxygen.
[0007] background
[0008] The production of air products in liquid or gaseous states by cryogenic air separation in air separation plants is well-known and extensively described in the technical literature. Among many others, reference can be made to H.-W. Häring (ed.), "Industrial Gases Processing", Wiley-VCH, 3006, in particular section 2.2.5, "Cryogenic Rectification". Unless explicitly defined otherwise, the terms used below have their usual meanings in the technical literature.
[0009] The noble gases krypton and xenon, which are present in atmospheric air at concentrations of approximately 1 ppm and 0.09 ppm (parts per million), can be obtained by processing larger volumes of air in air separation plants. The boiling points of krypton and xenon are significantly higher than those of nitrogen and oxygen. Therefore, krypton and xenon accumulate along with hydrocarbons in liquid oxygen in the rectification columns commonly used. The production of krypton and / or xenon products involves enrichment to obtain a krypton / xenon mixture, followed by the separation of this mixture, as explained in more detail below.
[0010] The aim of the present invention is to improve the processing of mixtures containing krypton and xenon, and in particular to improve the loss of krypton and xenon.
[0011] Overview
[0012] Against this background, a process and a plant for processing a feed mixture containing krypton, xenon, methane and oxygen are described with the P04327-EP
[0013] December 9, 2025 - Imhof
[0014] 2
[0015] Features of the independent claims are proposed. Further embodiments are the subject of the dependent claims and the explanations below.
[0016] The proposed method for processing a feed mixture comprises forming a first mass stream using the feed mixture, processing the first mass stream in a catalytic arrangement, extracting a second mass stream from the catalytic arrangement, and processing the second mass stream or part thereof in the form of a third mass stream in an adsorption arrangement.
[0017] In the proposed process, the feed mixture and the first stream contain krypton, xenon, methane, and oxygen. Using the catalytic arrangement, at least a portion of the methane in the second stream is catalytically reacted with oxygen to form carbon dioxide and water, with at least a portion of the carbon dioxide and water, along with at least a portion of the krypton, xenon, and oxygen from the first stream, being transferred to the second and third streams. Using the adsorption arrangement, at least a portion of the carbon dioxide and water in the third stream is removed.
[0018] The adsorption arrangement has several adsorber containers, wherein the adsorber containers are each subjected to a rinsing (at different times from each other) using a nitrogen-containing fourth stream during a rinsing period following an adsorption period, and wherein a fifth stream containing components desorbed during the rinsing period is taken from the adsorber containers.
[0019] The proposed process is characterized in particular by the fact that the fifth material stream, or a part thereof, is subjected to further processing within the process. In this way, krypton and xenon that would otherwise be lost during regeneration of the adsorber containers can be recovered.
[0020] The proposed method is based in particular on the finding that a significant proportion of product, especially xenon but also krypton, is conventionally lost during regeneration in the adsorption arrangement. This P04327-EP
[0021] December 9, 2025 - Imhof
[0022] 3
[0023] Losses are particularly noticeable when transferring from one adsorber container to another. These noble gas losses were recently confirmed by measurements in a real production plant, as explained in more detail below.
[0024] The adsorption period is followed by a pressure reduction phase, and the flushing process takes place during or immediately after this pressure reduction phase. In other words, the flushing phase includes the pressure reduction phase or a portion thereof. Another part of the flushing phase extends after the pressure reduction phase and occurs at a lower pressure level than during the adsorption period. The flushing process can be considered part of the regeneration process, which conventionally follows the adsorption phase.
[0025] Embodiments of the proposed process involve the further processing of the fifth material stream, or the aforementioned portion thereof, by using it in the formation of the first material stream. In other words, the loaded fifth material stream, or a portion thereof, is thus recycled back into the process to a position upstream of the catalytic arrangement.
[0026] In other words, particularly during a pressure reduction phase and the initial regeneration phase thereafter, nitrogen containing xenon and krypton can be generated via the aforementioned purging or a corresponding purging step. This nitrogen is then returned to the system at the inlet side of the catalytic unit, a known demethanization kit, thereby enabling the recovery of xenon in particular. Some carbon dioxide is also reintroduced into the system in this process. However, the absolute amount is so small that this does not represent a significant disadvantage.
[0027] Other embodiments of the proposed method include, as may also be the case in the embodiments described above, a rectification arrangement downstream of the adsorption arrangement. In a corresponding alternative embodiment, the fourth material stream can be guided through the adsorption vessels in the same direction as the third material stream, and the further processing of the fifth material stream can include transferring the fifth material stream or the portion thereof used accordingly into the rectification arrangement. P04327-EP
[0028] December 9, 2025 - Imhof
[0029] 4
[0030] The proposed method and its embodiments include, in particular, that the feed mixture contains 100 to 500 ppm, for example approximately 200 ppm, by volume xenon, 1,000 to 5,000 ppm, for example 2,500 ppm, by volume krypton, and more than 99% by volume oxygen. The proposed method and its embodiments are therefore particularly suitable for use with typical crude krypton / xenon from cryogenic air separation or a so-called C1 unit, as explained below.
[0031] The fourth material stream can contain nitrogen in particular, from 1 to 100% by volume, for example, 5 to 20% by volume. Such a composition enables particularly effective desorption and further processing of the fifth material stream in the process and its various configurations. The quantity can be, for example, 100 to 500 standard cubic meters of nitrogen per hour. The fourth material stream, if not composed exclusively of nitrogen, can also include, for example, argon and oxygen. The resulting fifth material stream can, as described above, be fed upstream of the reactor for methane combustion, i.e., the catalytic assembly; that is, the noble gas is recycled. Such a purging process is particularly effective in the recovery of krypton, since krypton is more readily desorbed by the purging gas or the fourth material stream than xenon.
[0032] As mentioned, the proposed method and its various configurations can include pressure reduction over a first sub-period of the purging cycle, followed by the flow of the fourth material stream through the adsorber tanks while retaining the fifth material stream over a second sub-period. A conventional regeneration process can then follow the purging cycle during a regeneration period.
[0033] The proposed method and its embodiments can include the provision that the further use of the fifth material stream occurs only during the purging period. This prevents a gas or gas mixture containing little or no noble gas from being reintroduced into the system or passed on to the rectification unit at later periods, thus avoiding a significant and unnecessary increase in the volume of gas to be processed. P04327-EP
[0034] December 9, 2025 - Imhof
[0035] 5
[0036] The proposed method and its embodiments can also include initiating purging or conventional regeneration of the adsorber tanks only when the carbon dioxide concentration detected in the adsorber tank exceeds a predetermined threshold. This ensures that switching between adsorber tanks is performed as late as possible, thus minimizing losses associated with switching simply by reducing the number of switches. In such a configuration, the adsorption and regeneration cycle runs for as long as possible to reduce losses incurred during the switchover. The magnitude of these losses is determined by the number of switches relative to the amount of feed gas processed.
[0037] In some configurations, the carbon dioxide content can be measured via measuring lines that exit the adsorber containers at a predetermined height relative to the height of the catalyst bed contained within the adsorber containers. This predetermined height can correspond to 50 to 98%, and in particular 80 to 90%, of the height of the catalyst bed.
[0038] To obtain the most accurate assessment of the loading status of the adsorption material in the adsorber vessels, such as a molecular sieve, such designs can be particularly advantageous. Carbon dioxide is measured, for example, in ppm. The cycle control can be automated based on the measured values to optimize the adsorber runtime. The carbon dioxide content indicates that the adsorber is almost completely loaded with carbon dioxide. This is because carbon dioxide, as a stronger adsorbate, displaces the previously adsorbed xenon from its adsorption sites during adsorption, thus making the xenon available again for rectification downstream. Another positive effect of a high carbon dioxide loading of the adsorber is, as mentioned, the reduction in regeneration frequency, since noble gas loss only occurs during pressure reduction and the subsequent regeneration of the adsorber.
[0039] The proposed plant for processing a feed mixture is designed for forming a first material stream using the feed mixture, processing the first material stream into a catalytic arrangement, extracting a second material stream from the catalytic arrangement, and processing the second material stream. P04327-EP
[0040] December 9, 2025 - Imhof
[0041] 6
[0042] or a part thereof in the form of a third material stream in an adsorption arrangement.
[0043] The feed mixture and the first stream contain at least krypton, xenon, methane, and oxygen, the system being configured to catalytically convert at least a portion of the methane in the second stream with oxygen to carbon dioxide and water, to transfer at least a portion of the carbon dioxide and water together with at least a portion of the krypton, xenon, and oxygen from the first stream into the second stream and into the third stream, and to remove at least a portion of the carbon dioxide and water from the third stream using the adsorption arrangement, the adsorption arrangement comprising several adsorber vessels, and the system being configured toto subject the adsorber containers to a rinsing process using a nitrogen-containing fourth stream during a rinsing period following an adsorption period, and to form a fifth stream during the rinsing period which contains components desorbed during the rinsing.
[0044] The plant is characterized in particular by the fact that it is designed to subject the fifth material stream or a part thereof to further processing in the process.
[0045] For further features and advantages of the proposed plant and its configurations, reference is expressly made to the features and advantages of the proposed process and its configurations explained above, as these apply to the plant in essentially the same way.
[0046] The same applies to a facility which, according to a design proposed here, may be set up to carry out a procedure according to a corresponding design.
[0047] Drawings
[0048] Embodiments are described below purely by way of example with reference to the attached drawing, wherein P04327-EP
[0049] December 9, 2025 - Imhof
[0050] 7
[0051] Figure 1 illustrates a system for processing a feed mixture containing krypton and xenon, which may form the basis of an embodiment;
[0052] Figure 2 illustrates a system for processing a starting mixture containing krypton and xenon according to a proposed embodiment;
[0053] Designs
[0054] The embodiments and configurations described below are provided solely to assist the reader in understanding the claimed and previously explained features. They represent only representative examples and are not intended to be considered exhaustive or limiting with regard to the features of the proposed methods and devices.
[0055] It is understood that the advantages, embodiments, examples, functions, features, structures and / or other aspects described above and below are not to be considered as limitations of the scope of the claims or as limitations of equivalents thereto, and that other embodiments may be used and modifications made without deviating from the scope of the claims.
[0056] Different embodiments may include, feature, consist of, or essentially consist of further advantageous combinations of the described elements, components, features, parts, steps, means, etc., even if such combinations are not specifically described herein. Furthermore, other embodiments may be included that are not currently claimed but could be claimed in the future, particularly if they are within the scope of the independent claims.
[0057] Explanations relating to devices, apparatus, arrangements, systems, etc., according to proposed embodiments may also apply to procedures, processes, methods, etc., according to other embodiments, and vice versa. Identical, functionally equivalent, structurally identical, or comparable elements, process steps, etc., may be indicated with identical reference numerals. P04327-EP
[0058] December 9, 2025 - Imhof
[0059] 8
[0060] The following explanations and definitions relating to some fundamental aspects of the invention may apply to all or part of the embodiments presented herein, and the explanation of certain aspects relating to only one part or one of the embodiments should not be understood to mean that these aspects cannot also be realized with other or all embodiments, insofar as technically possible and sensible.
[0061] The conjunction "and / or," when used before the last item in a list, should be understood to mean that all items mentioned before and after it can be combined in any way. In other words, "A, B and / or C" means "A and / or B and / or C" or "at least one of the elements A, B, and C in any combination."
[0062] In the sense understood here, an "operating cycle" is characterized by a sequence of process steps that are repeated in essentially the same way in another operating cycle. In the case of an adsorption process, this most simply consists of an adsorption step followed by a desorption step, or corresponding operating modes. Due to the saturation of the adsorbent with the gas component to be adsorbed, such a repeated, or "cyclical," sequence of process steps is necessary. Operating cycles can also include different durations of the individual process steps, for example, due to changing compositions, temperatures, and the like.
[0063] Typically, the process steps themselves do not change. However, in particular, the feed directions, flow directions, etc. of gases into certain apparatuses can be reversed between different operating cycles.
[0064] In an adsorption arrangement, two or more adsorption units, typically in the form of adsorption vessels filled with a suitable adsorbent material, are provided to ensure continuous operation. The adsorption units are operated sequentially, so that at least one unit is always in adsorption mode and at least one other unit is being regenerated simultaneously. Regeneration can be carried out, in particular, using a regeneration gas stream that is heated and fed in countercurrently (with respect to the P04327-EP).
[0065] December 9, 2025 - Imhof
[0066] 9
[0067] The adsorption mode is conducted through the adsorption units. Such operation requires switching between the adsorption vessels.
[0068] In the figures described below, components of comparable or identical function and / or design are indicated with identical reference numerals. Repeated explanations are omitted solely for the sake of clarity. Explanations relating to systems or their components apply accordingly to process steps carried out with them, and vice versa.
[0069] The production of krypton and xenon based on cryogenic air separation can be carried out in three subunits or steps, typically referred to as C1, O2, and O3. The C1 unit or step is generally part of an air separation plant or is carried out in such a plant, as described above. This produces so-called crude krypton / xenon, which has comparatively low concentrations of krypton and xenon and contains approximately 99.3% oxygen. In embodiments of the present invention, this can be used as a feed mixture.
[0070] The crude krypton / xenon from several air separation plants can be collected and transported to a C2 plant. Embodiments of the present invention may relate in particular to such a C2 plant or a process carried out therein. A C2 step serves to purify the crude krypton / xenon, mainly by removing oxygen and catalytically converting methane, which may also be present in the crude krypton / xenon, as it accumulates in the main condenser of an air separation plant. The product of the C2 plant or a corresponding process step is essentially a mixture of krypton and xenon with traces of impurities. The removed oxygen is typically used as a gaseous oxygen product at low pressure. Mixtures formed in several C2 plants can be fed to a C3 plant or a corresponding process step to produce pure krypton and xenon.The designation of the units or steps by 01, 02, 03 is not restrictive and the present invention can be used with other arrangements of plant components or process steps. P04327-EP.
[0071] December 9, 2025 - Imhof
[0072] 10
[0073] Figure 1 shows a system for processing a feed mixture containing krypton, xenon, methane, and oxygen, in particular the aforementioned crude krypton / xenon. The system illustrated in Figure 1 may be based on embodiments of the present invention, but does not itself necessarily represent an embodiment of the present invention.
[0074] The system illustrated in Figure 1 can represent a conventional C2 unit as just described. The system can, for example, include a tank 101, which can be filled, for instance, via tanker trucks with raw krypton / xenon from several C1 units, as abstracted as C1 in Figure 1. The raw krypton / xenon from tank 101 can, as mentioned, represent the component mixture referred to elsewhere in this disclosure as the feed mixture. This can be directed into a separator 102, from which a flash gas can be vented to atmosphere A or reliquefied and returned to the tank.The liquid from the separation vessel 102 can be pumped using a pump 103, partially buffered in a buffer vessel 104, and passed through a heat exchanger 105, which is operated with water W, steam, or ambient air, before optionally being combined with other liquids from tanks or pressurized gas containers 106 and 107, such as an externally supplied product from a C2 unit in a tank 106, a gas from a gas balloon of a C3 unit in a tank 107, or a gas from a gaseous oxygen collector 108 of another C2 unit. The units 102 to 105 can be provided in varying numbers in the system and each can hold a portion of the raw krypton / xenon.
[0075] The crude krypton / xenon is subsequently processed in the plant illustrated in Figure 1 in a catalytic arrangement 110, which includes a counterflow heat exchanger 111, an (electric) heater 112, a catalyst bed 113, a water-cooled cooler 114, and a condenser tank 115 for removing condensate C. In the catalyst bed 113 of the catalytic arrangement 110, traces of methane contained in the crude krypton / xenon can be converted into carbon dioxide and water. The resulting water (and any water already present) can be condensed into condensate C in a condenser tank 115. P04327-EP
[0076] December 9, 2025 - Imhof
[0077] 11
[0078] In the terminology used here, a first material stream 1, which is generated using the crude krypton / xenon, is supplied to the catalysis arrangement, and a second material stream 2 is removed. It should be emphasized that the description of certain system components or apparatus as belonging to a subunit, for example the catalysis arrangement 110, is not to be understood as restrictive and serves only for reference.
[0079] The second material stream, or a portion thereof, is then fed in the form of a corresponding material stream, referred to here as the third material stream 3, to an adsorption arrangement 120, which comprises a pair of adsorber vessels 121. These vessels may, for example, contain a molecular sieve material as the adsorbent, which is configured for regeneration using a regeneration gas R. Gaseous nitrogen or so-called waste oxygen can be used as the regeneration gas R. The regeneration gas R can be heated by means of an electric heater 117 and, after use for regeneration in the adsorption arrangement 120, released into the atmosphere A as a loaded adsorption gas stream. In the adsorption arrangement 120, water and carbon dioxide, in particular, are adsorbed, and the crude krypton / xenon thereby purified can be conveyed in the form of a material stream 6 via a counterflow heat exchanger 118 to a rectification arrangement 130.
[0080] The rectification arrangement 130, as shown in Figure 1, comprises a single rectification column 131 with a top condenser 132 and re-evaporators 133, which can be electrically operated. The top condenser 132 is cooled with liquid nitrogen N, which evaporates in an evaporation chamber of the top condenser 132 and is then, for example, vented into the atmosphere A as shown in Figure 1, with the corresponding mass stream being drawn off from the top condenser 132 on the left. A bottom stream from the rectification column 131 can be transferred to a C3 unit or a corresponding reaction step, as indicated by 03, or stored in a cylinder bundle 134 or transferred to a storage tank. Such options are not shown separately in Figure 1.
[0081] In the example of Figure 1, head gas from the rectification column 131 is used as waste oxygen, with or without passing through the counterflow heat exchanger 118,P04327-EP
[0082] December 9, 2025 - Imhof
[0083] 12
[0084] vented to atmosphere A or partially used as the regeneration gas R for the regeneration of the adsorption unit 120, as previously explained using the regeneration gas R.
[0085] In the system shown in Figure 1, the crude krypton / xenon, and thus the first material stream, can contain, for example, approximately 200 ppm xenon and 2500 ppm krypton, trace amounts of methane, and, in the remaining residue, typically more than 99 mol% oxygen. The crude krypton / xenon is purified in the adsorption unit 120 via a conventional molecular sieve process.
[0086] In particular, water and carbon dioxide are retained adsorbably in the adsorption unit 120. However, a disadvantage is that krypton and especially xenon are also adsorbed in the adsorption unit 120. Therefore, when the adsorption containers 121 are changed, i.e., when the pressure is reduced and the regeneration process is carried out, the adsorbed noble gases, especially xenon, are lost, since the loaded regeneration gas is typically released into the atmosphere A in conventional processes.
[0087] This is where embodiments of the present invention come into play. The aim here is to enable the highest possible yield of the noble gases krypton and xenon contained in the crude krypton / xenon. In other words, product losses in the process, particularly in the molecular sieve process, are to be reduced to a minimum.
[0088] The aspects just mentioned can be confirmed by measurements. For example, a measurement of xenon at the outlet of adsorber container 121 after initiating adsorption operation shows that xenon, in particular, is no longer detectable for approximately 20 minutes. This demonstrates that xenon is completely adsorbed by the adsorption material within this timeframe. After this period, the outlet concentration of xenon increases until it reaches a value similar to the inlet concentration.
[0089] In regeneration tests conducted with the aim of recovering as much adsorbed xenon as possible with a small amount of regeneration gas, it was found that after a pressure reduction in the adsorber containers 121 and during a subsequent purging phase, xenon can be desorbed and recovered using a relatively small amount of purge gas. P04327-EP
[0090] December 9, 2025 - Imhof
[0091] 13
[0092] A careful analysis of the noble gas yield for fine purification in two real-world plants reveals a yield loss of approximately 5% in each case due to the effects described. In these plants, which formed the basis of the corresponding investigation, the catalytic unit 110 was operated with a precious metal catalyst bed at approximately 480 °C. The primary function of the catalytic unit 110 is to convert methane (and nitrous oxide). From the catalytic unit 110, the crude krypton / xenon enters the molecular sieve adsorber, i.e., the adsorption unit 120. Here, moisture and carbon dioxide produced during methane combustion are essentially completely removed. Subsequently, the crude krypton / xenon enters a rectification column or rectification unit, which separates the krypton and xenon from the lighter oxygen in the bottom section. The krypton and xenon from the bottom section are then transferred to the C3 section for further separation.
[0093] The raw krypton / xenon, which comes from the tank and can have an oxygen content of 99.7% by volume, can be temporarily supplemented with balloon gas containing recycled noble gas. Although the amount added is small, for example 1 to 2% of the total feed gas volume, the krypton and xenon content can increase significantly because the balloon gas contains a high percentage of noble gas.
[0094] On one test day, the gas exiting adsorption unit 110 was analyzed at two time points after adsorber changes. The exiting mass flow, referred to here as the fourth mass flow, was 600 standard cubic meters per hour. Both events yielded a very similar concentration profile.
[0095] While the regenerated adsorber container 121 is being connected (parallel operation takes place for 15 minutes), the oxygen concentration initially drops from 99.7% by volume to approximately 70 to 85% by volume, particularly because the "fresh" adsorber container 121 still contains nitrogen. Similarly, the krypton concentration briefly drops from approximately 2,500 ppm to 1,100 ppm due to krypton adsorption in the fresh adsorber container 121. The xenon concentration falls from 200 ppm to 0 ppm by volume over 20 minutes due to adsorption. Therefore, no xenon enters a downstream rectification unit 130 or C2 rectification column over 20 minutes. Subsequently, P04327-EP
[0096] December 9, 2025 - Imhof
[0097] 14
[0098] The value rises above the feed concentration (temperature effect due to heat of adsorption) and then falls back to the feed concentration.
[0099] The missing amount of noble gas in the exiting adsorber gas, i.e., mass flow 6 according to Figure 1, can be calculated, taking into account the concentration drop and the subsequent overshoot. A xenon loss of 70 to 75 standard liters and a krypton loss of 130 standard liters were determined. Naturally, carbon dioxide is continuously adsorbed during the adsorber's operating time, which can displace xenon from its adsorption sites. However, the concentration differences compared to the feed gas are too small to be calculated. In particular, an adsorption vessel 121 operating at a reduced load, where the adsorption capacity for carbon dioxide is only partially utilized, still possesses a considerable adsorption capacity for krypton and xenon, thus leading to substantial yield losses.
[0100] At the end of the regeneration period, the corresponding adsorber container 121 is pressurized with raw krypton / xenon (for example, over a period of 40 minutes) and then operates in parallel with the other adsorber container 121 (for example, over a period of 15 minutes). Afterwards, the loaded adsorber undergoes a pressure reduction (for example, over a period of 25 minutes). This is followed, for example, by a 200-minute heating phase and a 400-minute cooling phase using, for example, 380 standard cubic meters of nitrogen as the regeneration gas. The regeneration gas is released into the ambient air via a silencer through the roof. The times mentioned already represent the extended periods according to the proposed embodiments of the invention, which are determined based on a carbon dioxide measurement. The original design times are 170 minutes for the heating phase and 274 minutes for cooling.
[0101] The pressure reduction of an adsorber vessel 121 from 7.5 bar gauge pressure to atmospheric pressure leads to high oxygen concentrations (98% oxygen by volume) at the regeneration gas outlet, as this was previously filled with almost pure oxygen. At the end of the pressure reduction, approximately 1,300 ppm xenon and 8,000 ppm krypton, both by volume, are measured at the regeneration outlet before the incoming regeneration gas dilutes the noble gases. In other words, a considerable amount of noble gas is desorbed even during the pressure reduction. DiesP04327-EP
[0102] December 9, 2025 - Imhof
[0103] 15
[0104] The proposed designs are taken into account by using a purge gas obtained over a corresponding period in Annex 100.
[0105] A few minutes after the start of the regeneration gas supply, for example at approximately 380 standard cubic meters per hour, krypton and xenon are almost completely removed from adsorber vessel 121. Carbon dioxide, on the other hand, is desorbed later. The peak carbon dioxide discharge is 3 to 3.5 volume percent and occurs approximately 2 hours after the start of the regeneration gas supply. However, the heating peak, which reaches its maximum at 130 °C, does not occur until 4 hours later. By this time, the carbon dioxide concentration has dropped to 300 ppm by volume. Clearly, the occurrence of the heating peak is more significant for moisture desorption than for carbon dioxide desorption.
[0106] Furthermore, it was tested whether rinsing a loaded adsorber with "small" amounts of nitrogen after pressure reduction could still desorb significant quantities of noble gases. Such a mixture could be transferred to a balloon and reintroduced at the beginning of the process. For this purpose, three phases were analyzed with regard to the noble gas production: pressure reduction, rinsing with nitrogen volumes in the range of 10 to 25 standard cubic meters per hour for 90 minutes, and subsequent "normal" regeneration with 380 Nm³ / h.
[0107] For this purpose, the operating program of the adsorber tanks 121 was modified by extending the pressure reduction phase from 25 minutes to 115 minutes. As soon as the pressure in the adsorber tanks 121 had dropped below 0.1 bar gauge pressure after 25 minutes, nitrogen gas was fed in from an external source via a regeneration gas inlet. Pressure transducers and rotameters were installed appropriately and in suitable positions. Nitrogen flow rate and quantity were determined, for example, by weighing a nitrogen tank before and after the purging test. At the time of two measurements on consecutive days, the discharge rate from the adsorber tanks was only 380 standard cubic meters per hour of raw krypton / xenon, in contrast to the previous measurements described above, which showed 600 standard cubic meters per hour. Two flushing tests were carried out, each lasting 90 minutes at flow rates of 9.5 and 24.6 standard cubic meters per hour. P04327-EP
[0108] December 9, 2025 - Imhof
[0109] 16
[0110] At the end of the purging process, regardless of whether the flow rate is 9.5 or 24.6 standard cubic meters per hour, there is still no reduction in the xenon concentration in the discharge gas. Clearly, purging for longer than 90 minutes or at a higher flow rate would be necessary. However, the analysis of the purging test at 24.6 standard cubic meters per hour shows that the initial xenon loss can be reduced from 6.04% to 1.51% if the pressure release gas and the purge gas can be reintroduced into the process.
[0111] The collection of the pressure release gas accounts for only 3% of the total xenon loss. Clearly, purge gas is necessary to release xenon from its adsorption sites. The use of a purge gas is very effective for krypton. Due to its lower adsorption capacity, the krypton loss in the purge test, using 24.6 standard cubic meters per hour, can be reduced from 1.69% to 0.09%.
[0112] When the heating peak passes the adsorber outlet after 4 hours of regeneration, very little noble gas is expelled. The xenon concentration in the regeneration gas rises from less than 0.1 ppm by volume to a maximum of 0.8 ppm by volume and then decreases again. Simultaneously, krypton concentration rises to 7 ppm by volume.
[0113] The gas collected during the pressure reduction and purging process, at a rate of 24.6 standard cubic meters per hour, contains an average xenon-to-krypton-to-carbon dioxide ratio of 1:3.7:8.5, meaning it still contains considerable amounts of carbon dioxide. However, these amounts are negligible during reinjection, as they are small compared to the raw krypton / xenon, which itself contains 2,500 ppm carbon dioxide by volume before reaching the adsorber.
[0114] During the flushing test, the outgoing purge flow, at a rate of 24.6 standard cubic meters per hour, maintains a higher oxygen concentration above 90% by volume for 20 minutes. After this time, the oxygen concentration drops very rapidly to less than 1% by volume. Therefore, the storage system or the path for direct re-feeding must be oxygen-compatible, i.e., designed for concentrations exceeding 23.5% by volume. A total of approximately 40 standard cubic meters per hour must be able to be received or fed into the catalytic unit via a downstream compressor during each flushing cycle. P04327-EP
[0115] December 9, 2025 - Imhof
[0116] 17
[0117] Even before the pressure in the adsorber tanks is released, the oxygen concentration at the regeneration gas outlet rises continuously to well over 21% by volume. Simultaneously, the noble gas concentrations in the regeneration gas outlet line increase. This line, located above the silencer, is actually open to the atmosphere and should contain only ambient air. It is suspected that the valves at the adsorber station are not completely airtight, allowing oxygen-rich raw krypton / xenon to enter the regeneration outlet. Because this line is unpressurized and open to the atmosphere, even small leaks from the feed line, which is pressurized at 7.5 bar, are immediately visible. Due to the unknown flow rate in this unpressurized line, the extent of the noble gas loss cannot be determined. Only a small loss is suspected.
[0118] Overall, the data obtained provide concrete recommendations for increasing the yield of xenon, which will be taken into account in the design of the proposed process.
[0119] Collecting the pressure release gas and the purge gas can significantly minimize xenon losses. For example, in the purge test with 24.6 standard cubic meters per hour, the yield loss was reduced from 6.04% to 1.51%, which translates to 48.5 NI xenon per regeneration. The purge gas mixture, which can be collected in a balloon, for instance, initially contains a high oxygen concentration, so this path must be suitable for oxygenation. As is the case in embodiments of the invention, the purge gas stream can also be fed directly into the methane reactor via a compressor without a buffer tank. Since xenon is relatively strongly adsorbed, a purge gas flow of at least 25 standard cubic meters per hour for at least 90 minutes is required to drive off the majority of the xenon from the adsorber.
[0120] The significant yield losses occur only during pressure reduction and subsequent regeneration; that is, the less frequently an adsorber is changed, the lower the xenon losses. Since adsorber switching cycles are not currently adjusted, particularly under low load, and thus the adsorber containers 121 are far from being fully loaded with carbon dioxide, large bed areas remain available for xenon adsorption. One objective could be to increase the overall carbon dioxide loading, as the more concentrated adsorbate, carbon dioxide, displaces the previously adsorbed xenon from its adsorption sites. P04327-EP
[0121] December 9, 2025 - Imhof
[0122] 18
[0123] The proposed method involves installing an analysis line at a specific bed height, and this analysis point must clearly detect traces of carbon dioxide (e.g., 2 ppm carbon dioxide by volume) before an adsorber change is initiated. Creating an additional analysis point in adsorber vessel 121 with a correspondingly adapted adsorber control system is relatively easy to implement.
[0124] The carbon dioxide loading capacity of the adsorber containers 121, which should be maximized, is influenced by the feed gas volume, the carbon dioxide concentration of the feed (which corresponds to a certain amount of hydrocarbons in the raw krypton / xenon), and the inlet temperature to the adsorber containers. Particularly under low load during the fine purification of the raw krypton / xenon, the proportional xenon losses are disproportionately high because the regeneration frequency is not currently adjusted.
[0125] Figure 2 illustrates a system according to an embodiment of the invention, designated by 100. As illustrated here, the adsorber containers 121 can be periodically subjected to a rinsing period following an adsorption period using a fourth material stream 4 containing nitrogen. During the rinsing period, a fifth material stream 5 is extracted from the adsorber containers 121, which contains components desorbed during the rinsing. The fifth material stream 5, or a portion thereof, is then subjected to further processing in the process. This processing consists of recirculating the fifth material stream 5 upstream of the catalytic arrangement 120 by means of a compressor 122.
Claims
P04327-EP December 9, 2025 - Imhof 19 Patent claims 1. A process for processing a feed mixture, comprising forming a first mass stream (1) using the feed mixture, processing the first mass stream (1) in a catalytic arrangement (110), extracting a second mass stream (2) from the catalytic arrangement (110), and processing the second mass stream (2) or a part thereof in the form of a third mass stream (3) in an adsorption arrangement (120), wherein the feed mixture and the first mass stream (1) contain krypton, xenon, methane, and oxygen, wherein, using the catalytic arrangement (110), at least a part of the methane in the second mass stream (2) is catalytically reacted with oxygen to form carbon dioxide and water, wherein at least a part of the carbon dioxide and water, together with at least a part of the krypton, xenon, and oxygen, are transferred from the first mass stream (1) into the second mass stream (2) and into the third mass stream (3).wherein at least a portion of the carbon dioxide and water in the third mass stream (3) is removed using the adsorption arrangement (120), and wherein the adsorption arrangement (120) comprises several adsorber containers (121), characterized in that the adsorber containers (121) are periodically subjected to rinsing using a nitrogen-containing fourth mass stream (4) during a rinsing period following an adsorption period, wherein a fifth mass stream (5) containing components desorbed during the rinsing is withdrawn from each of the adsorber containers (121), and wherein the fifth mass stream (5) or a portion thereof is subjected to further processing in the process.
2. The method of claim 1, wherein the further processing comprises use in the formation of the first material stream (1).
3. The method of claim 1, wherein a rectification arrangement (130) is connected downstream of the adsorption arrangement (120), wherein the fifth material stream (5) is guided through the adsorption vessels (121) in the same direction as the third material stream (3), and wherein the further processing comprises transferring the fifth material stream (5) or part thereof into the rectification arrangement (130). P04327-EP December 9, 2025 - Imhof 20 4. Method according to any of the preceding claims, wherein the starting mixture contains 100 to 500 ppm by volume of xenon, 1,000 to 5,000 ppm by volume of krypton and more than 99% by volume of oxygen.
5. Method according to any of the preceding claims, wherein the fourth material stream (4) comprises 1 to 100 volume percent nitrogen.
6. Method according to one of the preceding claims, wherein the flushing comprises a pressure reduction over a first partial period of the flushing period and a subsequent flow through the adsorber containers (121) with the fourth material stream (4) while retaining the fifth material stream (5) over a second period.
7. Method according to one of the preceding claims, wherein the rinsing and / or regeneration of the adsorber containers (121) is only initiated when a carbon dioxide content detected in the adsorber container (121) exceeds a predetermined threshold.
8. Method according to claim 7, wherein the carbon dioxide content is detected via measuring lines which are led out of the adsorber containers (121) at a predetermined height relative to a catalyst bed contained in the adsorber containers (121).
9. Method according to claim 8, wherein the specified height corresponds to 50 to 98% of the height of the catalyst bed.
10. Plant (100) for processing a feed mixture, which is configured for forming a first mass stream (1) using the feed mixture, processing the first mass stream (1) in a catalytic arrangement (110), extracting a second mass stream (2) from the catalytic arrangement (110), and processing the second mass stream (2) or a part thereof in the form of a third mass stream (3) in an adsorption arrangement (120), wherein the feed mixture and the first mass stream (1) contain at least krypton, xenon, methane, and oxygen, wherein the plant (100) is configured to catalytically convert at least a part of the methane in the second mass stream (2) with oxygen to form carbon dioxide and water using the catalytic arrangement (110), and at least a part of the P04327-EP December 9, 2025 Imhof 21 to transfer carbon dioxide and water together with at least a part of the krypton, xenon and oxygen from the first material stream (1) into the second material stream (2) and into the third material stream (3), and to remove at least a part of the carbon dioxide and water in the third material stream (4) using the adsorption arrangement (120), wherein the adsorption arrangement (120) comprises several adsorber containers (121), characterized in that the system (100) is configured to periodically subject the adsorber containers (121) to rinsing using a nitrogen-containing fourth material stream (4) during a rinsing period following an adsorption period, to extract a fifth material stream (5) from the adsorber containers (121) during the rinsing period, which contains components desorbed during the rinsing, and to subject the fifth material stream (5) or a part thereof to further processing in the process.
11. Plant (100) according to claim 10, which is set up to carry out a method according to any one of claims 1 to 9.