Fluid recovery method and device for xenon and / or krypton gas recovery

Abstract

A method for recovering at least one fluid (e.g., xenon and / or krypton, etc.) from a feed gas may include utilizing a compression system, a primary heat exchanger unit, a pre-purification unit (PPU), and other units to separate and recover at least one desired fluid. In some embodiments, a fluid stream output from a first heat exchanger or separation system of the device may be split so that a portion of the stream is output for downstream processing to purify a xenon (Xe) and / or krypton (Kr) product stream, while another portion of the stream is recovered to a compression system or PPU for further purification and heat exchange so that the product output for downstream processing has a higher Xe or Kr concentration. Some embodiments may be configured to provide improved Xe and / or Kr recovery and improved operating efficiency.

Description

Technical Field

[0001] The present innovation relates to methods for recovering fluids (e.g., xenon, krypton, oxygen, argon and / or nitrogen) from air, gas separation apparatus configured to recover xenon and / or krypton in addition to nitrogen, argon and / or oxygen from at least one feed gas, air separation apparatus utilizing multiple towers to recover xenon and / or krypton fluids in addition to nitrogen, argon and / or oxygen fluids, air separation systems, systems, and methods of making and using the same. Background Art

[0002] Air separation processes can be configured to recover noble gases such as xenon (Xe) or krypton (Kr) as well as neon (Ne), helium (He) and / or argon (Ar). U.S. Patent Nos. 4,568,528, 5,309,719, 6,164,089, 6,658,894, 6,735,980, 6,843,973, 6,848,269, 7,285,154 and 8,795,411 disclose examples of such systems.

[0003] Historically, neon, argon, krypton, and xenon have been recovered as secondary products in the cryogenic separation of air into oxygen and / or nitrogen products. Argon, krypton, and xenon can also be recovered from purge gases produced in the synthesis gas production of ammonia from air and natural gas. Krypton and xenon are used in many specialized fields, including research, medicine, instrumentation, lighting, and space applications.

[0004] Since air contains only 1.14 and 0.087 parts per million by volume (ppmv) of krypton and xenon, respectively, recovery of these components by cryogenic separation of air can be technically complex and costly. Recovery is often further complicated by the presence of light hydrocarbons (e.g., methane) in the air feed to the air separation unit. Krypton, xenon, and methane, due to their boiling points relative to oxygen and nitrogen, can be concentrated in liquid oxygen during the distillation process. Summary of the invention

[0005] We have determined that when a xenon and / or krypton-rich purge stream is produced in an air separation column, it is desirable to minimize its flow rate. We have determined that minimizing the flow rate of such a stream facilitates further downstream purification to obtain a xenon (Xe) and / or krypton (Kr) product stream that is high in concentration, sufficient to be economically transported to another location for further processing to form a Xe and / or Kr fluid product (e.g., a concentration of at least 20 mol% (mole percent) Xe or at least 20 mol% Kr), or a concentration high enough to enable downstream processing facilities of the device to form a Xe or Kr product stream (e.g., at least 90 mol% Xe, at least 90 mol% Kr, at least 95 mol% Xe, at least 95 mol% Kr, at least 99 mol% Xe, at least 99 mol% Kr, etc.).

[0006] We also determined that carbon dioxide (CO 2 ) and nitrous oxide (N 2 Low volatility components such as CO can be concentrated with Xe and / or Kr, and their low solubility limits can determine the minimum flow rate of the Xe and / or Kr-rich purge stream. 2 / N 2 The O content determines the purge flow rate for this stream, and we determined that it would be best to recycle a portion of the stream so that it could be recycled back to the front-end pre-purification unit (PPU) or compression system, where it would then be compressed and then passed to the PPU along with the compressed feed air so that the recycled portion could be passed back through the PPU, where it could further remove CO. 2 / N 2 O component. We have determined that recycling this portion of the Xe and / or Kr-rich purge stream can accumulate Kr and Xe to a higher concentration in the purge stream, output for downstream processing, and form a Xe and / or Kr product stream. It also allows the flow rate of the purge stream to be minimized. We have determined that this Xe and / or Kr purge stream processing method can use a smaller PPU and downstream processing equipment in the device, which helps to reduce capital costs, while also allowing a higher purity Xe product stream and / or Kr product stream to be obtained through downstream processing, or a more conventional purity of these product streams to be obtained at a lower processing cost. Embodiments can also help provide improved operational flexibility.

[0007] We have determined that methods and apparatus utilizing embodiments of our improved Xe and / or Kr recovery schemes allow for smaller flow rates of Xe and / or Kr-rich streams to be sent to downstream processing while also having higher Xe concentrations and / or higher Kr concentrations than conventional systems without the need to use one or more cryogenic CO 2 / N 2O adsorber or significantly oversized front-end prepurifier adsorber. This can reduce the cost of further downstream processing of the Xe and / or Kr purge stream without affecting the cost of the air separation unit (ASU). We have found that recycling a portion of the Xe and / or Kr-rich purge stream upstream of the front-end PPU to remove additional CO in the recycle stream 2 and N 2 O, which greatly improves the process efficiency while also making the process more resilient to poor performance of the front-end adsorber, thereby facilitating higher CO 2 / N 2 O slips into the cold box are well tolerated. If this is detected to occur, for example, due to deactivation of adsorbent or catalytic materials, the process can be modified to address this by increasing the portion of the Xe and / or Kr-rich purge stream recycled upstream for further purification through the PPU.

[0008] As another example, in some cases, the PPU may be designed so that the CO in the purge stream 2 and N 2 The purge flow required to keep O below the threshold results in relatively high purge flows and very low Xe concentrations and / or very low Kr concentrations. We have determined that in such cases, recycling a portion of the Xe and / or Kr-rich purge flow upstream of the front-end PPU to remove additional CO in the recycle flow 2 and N 2 O can also greatly improve the process efficiency while also making the process more resilient to poor performance of the front-end adsorber and thus to higher CO 2 / N 2 O Slide into the cold box with good tolerance.

[0009] We have determined that recycling a portion of the Xe and / or Kr-rich purge stream upstream of the front-end PPU can help to retrofit an existing ASU with a Xe and / or Kr-rich purge having a relatively low Xe concentration and / or Kr concentration to improve the Xe and / or Kr recovery and increase the operating efficiency of the ASU being retrofitted. For example, an ASU retrofitted to utilize an embodiment of our Xe and / or Kr recovery method can have a Xe concentration and / or Kr concentration in the Xe and / or Kr-rich purge stream high enough to allow Xe and / or Kr recovery through downstream processing without losing the Xe and / or Kr component.

[0010] In other retrofit situations, the ASU may have pre-existing downstream processing capabilities to form product streams of Xe and / or Kr, and the retrofit operation may allow the use of smaller processing equipment to accomplish such downstream processing, allowing a lower flow rate of a Xe and / or Kr-rich purge stream to be delivered for downstream processing. Such size reduction may reduce operating costs, i.e., by reducing the size and process requirements of such streams, as well as reducing capital costs.

[0011] Another disadvantage of oversizing the front-end adsorber that can be addressed by utilizing embodiments of our Xe and / or Kr recovery schemes is the increased Xe losses through co-adsorption of Xe on 13X or other X zeolite type adsorbents (e.g., NaMSX, NaLSX, CAX) commonly found in air prepurifiers. In some cases, when the front-end adsorber of a PPU is sized to remove both CO 2 and N 2 At 0, the Xe loss caused by this co-adsorption may be close to 8%. Embodiments of our Xe and / or Kr recovery scheme can minimize or completely avoid this loss of Xe because a smaller PPU can be utilized, and one or more adsorption beds of the PPU can also utilize different catalysts or zeolites to minimize (if not eliminate) the co-adsorption of Xe. This can also help to increase the Xe concentration in the Xe and / or Kr-rich purge stream.

[0012] Embodiments incorporating this method may include, in the case of a method for removing CO 2 and N 2 Small pore zeolites, such as 4A zeolite (also known as NaA zeolite), are used in the front-end adsorber for O. The pore size of 4A zeolite is large enough to adsorb CO in it. 2 and N 2 O, but can also be small enough to exclude most of the Xe in the purified fluid, so that a higher Xe recovery can be obtained through the front-end adsorber of the PPU and concentrated in the downstream cryogenic process. 4A zeolite can completely or partially replace 13X zeolite. In some embodiments, it is most advantageous to size 4A zeolite to remove CO 2 and some N 2 O, while retaining some 13X zeolite to remove trace hydrocarbons and residual N 2 In some embodiments, 4A zeolite can be used to completely replace 13X zeolite to reduce Xe loss by up to 10 times. In addition to 4A zeolite, other small pore zeolites can also be used, or as a substitute for them. These other small pore zeolites can include, for example, chabazite, rho, calcite or maltite, and cation combinations in these zeolites. In some of these embodiments, A zeolite can include one or more of sodium (Na), potassium (K), calcium (Ca) and zinc (Zn).

[0013] In a first aspect, an embodiment of a method for separating a feed gas comprising oxygen, nitrogen, and argon (e.g., air) may include purifying the compressed feed gas by a pre-purification unit (PPU) before feeding the purified and compressed feed gas to a first separation system to form at least one product stream from the feed gas. The at least one product stream may include a nitrogen stream, an oxygen stream, and / or an argon stream. The method may also include outputting a first purge stream comprising xenon (Xe) and / or krypton (Kr) from the first separation system, and splitting the first purge stream so that a first portion of the first purge stream is directed to at least one downstream processing unit (DPU) to form a first product stream comprising Xe and / or a second product stream comprising Kr, and a second portion of the first purge stream is directed upstream of the PPU for additional purification by the PPU.

[0014] In a second aspect, embodiments of the method may further include, in response to carbon dioxide (CO 2 ) and / or nitrous oxide (N 2 O) reaches or exceeds a first preselected threshold value, the split of the first purge flow is adjusted so that the flow rate of the first portion of the first purge flow directed to at least one DPU is reduced, and the flow rate of the second portion of the first purge flow directed to the PPU is increased, so that the portion of the first purge flow recycled to the PPU is increased.

[0015] In a third aspect, the method may further include, in response to carbon dioxide (CO 2 ) and / or nitrous oxide (N 2 O) when the concentration reaches or exceeds a first preselected threshold, adjusting the split of the first purge flow so that the portion of the first purge flow directed to the PPU increases, so that the portion of the first purge flow recycled to the PPU increases. The embodiments utilizing the third aspect may be used in combination with the first aspect and / or the second aspect.

[0016] In an embodiment of the method, the PPU may include an adsorbent material. The adsorbent material may include a material that adsorbs one or more undesirable impurities from the feed. In some embodiments, the adsorbent material may include a zeolite having a pore size configured to receive and adsorb CO in the present invention. 2 and N 2 O, while rejecting most of the Xe in the compressed feed gas being purified in the PPU. For example, the adsorbent material may include 4A zeolite, chabazite, rho, calcite and / or formosite.

[0017] In a fourth aspect, the method can be configured such that the splitting of the first purge stream is performed via a valve or splitting device, such that a first portion of the first purge stream is directed to at least one DPU to form a first product stream comprising Xe and / or a second product stream comprising Kr, and a second portion of the first purge stream is directed upstream of the PPU for additional purification by the PPU. In some embodiments, the valve or splitting device may be located outside the cold box.

[0018] In a fifth aspect, the method can be configured to perform a split of the first purge stream by a first heat exchanger located downstream of the PPU and upstream of the first separation system, such that a first portion of the first purge stream is directed to at least one DPU to form a first product stream comprising Xe and / or a second product stream comprising Kr, and a second portion of the first purge stream is directed upstream of the PPU for additional purification by the PPU. In some embodiments, the first heat exchanger can be a heat exchanger of a cold box or be configured as a cold box.

[0019] In a sixth aspect, the method can be configured to perform a split of the first purge stream outside the cold box or in the cold box, such that a first portion of the first purge stream is directed to at least one DPU to form a first product stream comprising Xe and / or a second product stream comprising Kr, and a second portion of the first purge stream is directed upstream of the PPU for additional purification by the PPU.

[0020] In some embodiments of the method, there may be an apparatus that includes multiple different ASUs that utilize different embodiments of the method, or there may be multiple ASUs in combination that utilize embodiments of the method. In other embodiments of the method, an apparatus may include a single ASU that utilizes an embodiment of the method.

[0021] In a seventh aspect, an apparatus for recovering xenon (Xe) and / or krypton (Kr) is also provided. Embodiments of the apparatus may be configured to utilize one or more of the methods of the first to sixth aspects discussed above or other embodiments discussed herein.

[0022] In the eighth aspect, an embodiment of the apparatus may include a diverter device positioned to divert a first purge stream comprising xenon (Xe) and / or krypton (Kr) output from a first separation system such that a first portion of the first purge stream is directed to at least one DPU to form a first product stream comprising Xe and / or a second product stream comprising Kr, and a second portion of the first purge stream is directed upstream of a PPU, the PPU being positioned to purify compressed feed gas for feeding to the first separation system.

[0023] The device may be configured to be retrofitted into a device or ASU, or may be configured to be included in a new device or ASU.

[0024] In a ninth aspect, the apparatus may include a PPU. The PPU may be positioned to receive a compressed feed gas to purify the compressed feed gas for sending the compressed feed gas to a first separation system to form at least one product stream from the feed gas. The at least one product stream may include a nitrogen stream, an oxygen stream, and / or an argon stream. An embodiment of an apparatus including a PPU may be configured such that the PPU includes an adsorbent material, the adsorbent material includes a zeolite having a pore size, the pore size of the zeolite being configured to receive and adsorb carbon dioxide (CO 2 ) and / or nitrous oxide (N 2 O) while removing most of the Xe in the compressed feed gas. The adsorbent material may include, for example, 4A zeolite, chabazite, rho, calcite and / or maltite.

[0025] In the tenth aspect, the device may include a first separation system. The first separation system may be configured to output a first purge stream containing Xe and / or Kr, and form at least one product stream including a nitrogen stream, an oxygen stream, and / or an argon stream. In some embodiments, the first separation system may include a plurality of towers. In some embodiments of the device, the seventh aspect may include the eighth, ninth, and / or tenth aspects.

[0026] In the eleventh aspect, the flow diversion device may include a valve, or the flow diversion device may be located in the first heat exchanger downstream of the PPU and upstream of the first separation system. In some embodiments, the first heat exchanger is a first heat exchanger of a cold box or is configured as a cold box.

[0027] In the twelfth aspect, the apparatus may be designed such that the flow splitting device is configured to split the first purge flow so as to respond to the carbon dioxide (CO 2 ) and / or nitrous oxide (N 2 O) concentration reaches or exceeds a first preselected threshold value, so that the portion of the first purge stream directed to at least one DPU is reduced and the portion of the first purge stream recycled to the PPU is increased.

[0028] In the thirteenth aspect, the apparatus may be designed so that the splitting device is configured to split the first purge flow so as to respond to the carbon dioxide (CO 2 ) and / or nitrous oxide (N 2 O) concentration reaches or exceeds a first preselected threshold value, so that the flow rate of the second partial flow of the first purge flow directed to the PPU is increased to a first increased flow rate, so that the portion of the first purge flow recycled to the PPU is increased.

[0029] In some embodiments, the apparatus may be configured to utilize a combination of the twelfth and thirteenth aspects with the seventh, eighth, ninth, tenth, and / or eleventh aspects. These embodiments may utilize aspects of the method, including one or more of the first, second, third, fourth, fifth, and sixth aspects.

[0030] Other elements may also be included in embodiments of the system or device. For example, one or more pumps, containers or other units may also be used in embodiments of the system or device. It should be understood that embodiments of the system or device may be constructed and configured to utilize at least one embodiment of an enhanced Xe and / or Kr recovery method.

[0031] Additional details, objects and advantages of our methods for recovering fluids (e.g., xenon and / or krypton in addition to oxygen, argon and / or nitrogen) from air, gas separation apparatus configured to recover xenon and / or krypton in addition to nitrogen, argon and / or oxygen from at least one feed gas, air separation apparatus utilizing multiple towers to recover xenon and / or krypton in addition to nitrogen and / or argon and / or oxygen fluids, air separation systems, systems, apparatus utilizing these systems or methods, and methods of making and using them will become apparent as the following description of certain exemplary embodiments thereof proceeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Exemplary embodiments of methods for recovering fluids (e.g., xenon and / or krypton in addition to oxygen, argon and / or nitrogen) from air, gas separation apparatus configured to recover xenon and / or krypton in addition to nitrogen, argon and / or oxygen from at least one feed gas, air separation apparatus utilizing multiple columns to recover xenon and / or krypton in addition to nitrogen and / or argon and oxygen fluids, air separation systems, systems, apparatus utilizing these systems, and methods of making and using them are shown in the drawings herein. It should be understood that like reference numerals used in the drawings may identify like components.

[0033] Figure 1 is a schematic block diagram of a first exemplary embodiment of an apparatus utilizing a first exemplary embodiment of an air separation process. Figure 1 The middle dashed line shows the optional vaporizer 16. The optional vaporizer 16 may be configured to vaporize the purge stream 106 in the event that the purge stream is output from the cold box 14 as a liquid or a mixture of liquid and vapor.

[0034] Figure 2 is a schematic block diagram of a second exemplary embodiment of an apparatus utilizing a second exemplary embodiment of an air separation process.

[0035] Figure 3 is a block diagram of an exemplary controller that may be used in the first exemplary embodiment of the apparatus or the second exemplary embodiment of the apparatus. DETAILED DESCRIPTION

[0036] Reference Figure 1-3 , the apparatus 10 may be configured to utilize an air separation process, which may be configured to facilitate recovery of at least one xenon and / or krypton fluid stream in addition to the argon, nitrogen and / or oxygen fluid product stream 114. Embodiments of the apparatus 10 may utilize a controller to help monitor and / or control the operation of the apparatus 10. In some embodiments, the apparatus 10 may be configured as an air separation system or a cryogenic air separation system. The apparatus 10 may be a stand-alone facility, or may be a facility incorporated into a larger facility with other devices (e.g., a manufacturing plant for manufacturing goods, a mineral refining facility, a power plant, etc.). The apparatus 10 may have a single air separation unit (ASU) that may employ an embodiment of the air separation process or may utilize multiple different ASUs. One or more ASUs in an embodiment of an apparatus having multiple ASUs may utilize an embodiment of the air separation process.

[0037] Reference Figure 1-3 , embodiments of the apparatus 10 may include a gas feed 100. The feed 100 may be air obtained from the atmosphere outside the apparatus 1, or may be a process gas obtained from a facility connected to the apparatus 1. The feed 100 may be compressed in a main compression system 11, which in some embodiments may also be referred to as a "MAC". A first stream of compressed feed fluid may be output from the compression system 11 and sent to a pre-purification unit (PPU) 13 via a PPU feed pipeline for purifying the pressurized feed 100 to remove certain components of the feed after it is compressed. The compressed air output from the compression system 11 may be passed through at least one cooler 12 ( Figure 1 In other embodiments, such a cooler cannot be used.

[0038] The PPU 13 may be configured to include one or more adsorbers configured to remove trace components from the feed that may have relatively high boiling points or may be undesirable impurities that may represent possible operational problems, such as carbon dioxide (CO 2 ), carbon monoxide (CO), nitrous oxide (N 2 O), hydrogen (H 2 ), heavier hydrocarbons (such as ethylene, acetylene and / or butane, etc.) and / or water (H 2 O).

[0039] In some embodiments, the compression system 11 may output the compressed feed as a pressurized gas stream 102 (e.g., a pressurized air feed) to the PPU 13, and the PPU 13 may output the pressurized gas stream as a purified and pressurized gas stream 104 after removing various components therefrom. The purified and pressurized gas stream 104 may include, for example, 76-79% by volume nitrogen (N 2 ), 20-22% volume oxygen (O 2 ) and 0.8%-3% volume argon (Ar) or 76.59-78.12% volume N 2 , 20.5-20.95% volume O 2 and 2.87-0.93% volume Ar. In addition, the purified and pressurized gas stream 104 may also include 0.080-0.094 ppmv xenon (Xe) and 1 ppmv to 1.2 ppmv krypton (Kr).

[0040] The purified and pressurized gas stream 104 may be output from the PPU 13 and subsequently fed to a first heat exchanger (HX) 15 of the cold box 14 via at least one PPU HX feed conduit. In some embodiments, the first HX 15 may be considered the main heat exchanger of the cold box 14, or the primary heat exchanger of the cold box 14 (in the Figure 1 and Figure 2 (shown schematically by dashed lines).

[0041] The purified and pressurized gas stream 104 may be fed directly from the PPU 13 to the first HX 15 via at least one conduit, or may be divided into multiple streams and fed to the first HX 15. For example, in some embodiments, the purified and pressurized gas stream 104 may include a first partial stream fed to the first HX 15 via at least one conduit and a second partial stream fed to the first HX 15. The piping arrangement may include a valve or other type of flow splitting mechanism to split the purified and pressurized gas stream 104 into multiple streams. In some embodiments, some of the split streams may be further compressed before being fed to the first HX 15, while one or more other streams are fed directly to the first HX from the PPU 13. These embodiments may also utilize one or more other second heat exchangers to cool the split stream fluids instead of feeding the streams to the first HX 15 or before feeding the split streams to the first HX 15.

[0042] In these embodiments, the pressure of the first partial stream of the purified and pressurized gas stream 104 can be a pressure between 5 atmospheres (atm) and 30 atm or between 5 bar and 30 bar. After further pressurization to form a further pressurized second partial stream, the pressure of the second partial stream of the purified and pressurized gas stream 104 can be between 5 atm and 100 atm. For example, in some embodiments, the pressure of the first partial stream of the purified and pressurized gas stream 104 can be between 5-15 atm, 5-25 atm, or 10-30 atm, and the pressure of the further pressurized second stream of the purified and pressurized gas stream 104 can be greater than 5 atm and less than 100 atm, greater than 10 atm and less than 75 atm, or greater than 10 bar and less than 70 bar. In other embodiments, there may be only a single purified and pressurized gas stream 104, the pressure of which ranges from any of the above pressure ranges (e.g., between 5 atm and 100 atm, 5-15 atm, 5-25 atm, 5-30 atm, or 10-30 atm, etc.).

[0043] The purified and pressurized gas stream 104 may be cooled in the first HX 15 of the cold box 14 to form a first cooled first heat exchanger output stream 112, which is fed to the first separation system 17 of the cold box 14. The first separation system 17 of the cold box 14 may include a high pressure (HP) tower 107 of a multi-tower assembly (e.g., a column or tower having multiple towers operating at different pressures through at least one high pressure tower feed conduit) and a low pressure (LP) tower. The HP tower may be considered the first tower of the multi-tower assembly, operating at the highest pressure of the towers of the multi-tower assembly. For example, the operating pressure of the HP tower may be higher than the operating pressure of the second tower (e.g., LP tower) of the multi-tower assembly.

[0044] The LP column can be considered as the second column of the multi-tower assembly, and its operating pressure is lower than the operating pressure of the first column (e.g., HP column). In some embodiments, the LP column of the first separation system 17 can be operated at a pressure between 1.1 atm and 8 atm, between 1.1 atm and 3 atm, or greater than 1 bar and less than 8 bar, and the HP column 107 can be operated at a pressure between 4 atm and 20 atm, between 4.5 atm and 12 atm, or greater than 4 bar and less than 12 bar.

[0045] The HP column and the LP column of the first separation system 17 can be positioned and configured to process the cooled purified and pressurized gas stream 104 output from the first HX 15 (and air cooled from other parallel second heat exchangers, if utilized as discussed herein) as a first cooled first heat exchanger output stream 112 via at least one first separation system feed conduit. One or more streams sent from the first HX 15 to the first separation system 17 can be processed by the first separation system 17 to form oxygen (O 2 ) and / or nitrogen (N 2) and / or argon (Ar) fluid as a product fluid and / or used as a process fluid in other elements of the apparatus 10. In some embodiments, additional product streams may also be generated, which may include at least one waste stream 116, which may be passed to the first HX 15 as a cooling medium for absorbing heat from the purified and pressurized gas stream 104 and fed to the first HX. The waste stream 116 may include at least one nitrogen-rich or oxygen-rich waste stream, which may be used as a cooling medium and / or adsorber regeneration fluid before being output as at least one effluent of the apparatus 10 or before being used in another apparatus process (e.g., as a process gas in another apparatus process).

[0046] For example, a device 10 configured to produce oxygen as a primary product may have at least one nitrogen-rich waste stream or regeneration fluid used as a cooling medium for regenerating adsorbent material or catalytic material used in at least one offline adsorber of the PPU 13. As another example, a device 10 configured to produce nitrogen as a primary product may have at least one oxygen-rich waste stream used as a cooling medium or regeneration fluid for regenerating adsorbent material or catalytic material used in at least one offline adsorber of the PPU 13.

[0047] The nitrogen-rich product stream 114 may include 100-99 volume percent (vol.%) nitrogen, which may be output from the first separation system 17 as a first product stream 114. An oxygen-rich liquid and / or vapor stream may be output as the product stream 114 such that the oxygen concentration in each of these streams is at least 90 mole percent (mol%) oxygen or greater than or equal to 99.5 mol% oxygen. In some embodiments, the argon-rich product stream 114 may include 0-4 vol.% oxygen, 0-0.5 vol.% nitrogen, and the balance argon (e.g., 100-95.5 vol.% argon). The product stream 114 may be output as a liquid product, or may be sent to at least one heat exchanger to form a gas product stream (e.g., sent to the first heat exchanger 15 or another heat exchanger of the apparatus 10 for vaporization).

[0048] In addition to forming the product stream 114, the first separation system 17 of the cold box 14 can also form a purge stream 105 rich in Xe and / or Kr for feeding from the first separation system 17 to the first HX 15 via a purge stream conduit, or form a purge stream 105a rich in Xe and / or Kr for feeding to a gasifier 16 outside the cold box 14 for feeding via a purge stream conduit ( Figure 1The Xe and / or Kr-rich purge stream 105 or 105a may include 200-1,000 ppmv Kr and 15-200 ppmv Xe, or may include up to 1,000 ppmv Kr and at least 30 ppmv Xe, or may include only 15-100 ppmv Xe (without Kr, minimal Kr, or trace amounts of Kr for the process of apparatus 10). In other embodiments, the Xe and / or Kr-rich purge stream 105 or 105a may include 30-80 ppmv Xe, without Kr, minimal Kr, or up to at least 1000 ppmv Kr.

[0049] In some embodiments, purge stream 105 or 105a may have a minimum allowable flow rate. For example, in an embodiment of apparatus 10, where CO 2 and / or N 2 The solubility limit of O in the purge stream can be used to establish a minimum flow rate threshold for the purge stream 105 or 105a. 2 and / or N 2 In embodiments where the solubility limit of O is not a control parameter for the purge flow rate, the minimum purge flow rate may be determined based on a preselected allowable hydrocarbon content in the purge stream 105 or 105a. In some embodiments, the apparatus 10 may be operated such that the purge stream 105 or 105a has a minimum allowable flow rate based on such control criteria.

[0050] In some embodiments, the purge stream 105 rich in Xe and / or Kr can be output as the final liquid purge stream of the first separation system 17 and / or the cold box 14. For the oxygen-producing air separation system, the purge stream 105 rich in Xe and / or Kr can be a liquid oxygen purge stream output from the sump of the LP tower. The purge stream 105 rich in Xe and / or Kr can be formed as the output of the LP tower, or can be output after the liquid oxygen purge stream is evaporated to further concentrate the Xe and Kr in the purge stream 105 rich in Xe and / or Kr.

[0051] For embodiments of the apparatus 10 configured as an air separation unit that produces a nitrogen product without a significant oxygen product, a crude liquid oxygen purge stream output from a low pressure boiler can be the source of a Xe and / or Kr-rich purge stream 105. For such embodiments, the Xe and / or Kr-rich purge stream 105 can be formed by a purge reboiler and / or a stripper that can process the crude liquid oxygen purge stream to form a Xe and / or Kr-rich purge stream 105.

[0052] The Xe- and / or Kr-rich purge stream 105 output from the first separation system 17 of the cold box 14 can be fed to the first HX 15 to be heated therein, while also acting as a cooling medium for the pressurized and purified gas stream 104 supplied thereto. The heated Xe- and / or Kr-rich purge stream 106 can be output from the first HX 15 of the cold box or gasifier 16 and directed to the downstream processing unit (DPU) 21. For example, the DPU 21 can include a plurality of distillation columns, or can be configured to use one or more adsorbers alone, or in combination with one or more distillation columns. Other embodiments can utilize strippers, columns, or other processing elements. In some embodiments, these elements can be arranged to be used in combination with one or more adsorbers and / or one or more distillation columns.

[0053] DPU 21 may be configured to form a product stream rich in Xe and / or Kr (e.g., a Xe product stream having a mole percentage of at least 10%, at least 20%, at least 30%, at least 50%, more than 80%, more than 90%, or more than 99% Xe and / or a Kr product stream having a mole percentage of at least 10%, at least 20%, at least 30%, at least 50%, more than 80%, more than 90%, or more than 99% Kr). The preselected purity of the Xe and / or Kr product stream exiting DPU 21 may depend on the existing concentration of the stream, whether it is a finished gas or is to be shipped elsewhere for further processing.

[0054] In some embodiments, the DPU 21 may be configured such that the feed stream is pre-pressurized to at least 4 atm before being fed to the DPU. This pressurization may be provided by at least one compressor positioned as a component of the DPU 21 or a pre-compression system of the DPU 21. When necessary, the pressure may be increased by increasing the static head or a pump. This pressure increase may be configured to occur outside the cold box 14 or may be provided before the purge stream 105 or 105a is fed to the first HX 15 or the gasifier 16.

[0055] Prior to being delivered to the DPU 21, the heated Xe and / or Kr-rich purge stream 106 may be diverted by a heated Xe and / or Kr-rich purge stream diverting device 19, which may include a valve or other flow control element. A first portion 110 of the heated Xe and / or Kr-rich purge stream may be directed to the DPU 21 by the heated Xe and / or Kr-rich purge stream diverting device 19, while a second portion 108 of the heated Xe and / or Kr-rich purge stream may be recycled back to the compression system 101 or a location downstream of the compression system 101 and upstream of the PPU 13, such that the recycled second portion is passed through the PPU 13 again for further purification to further remove any CO that may be included therein. 2 or N 2 O. The flow diversion device 19 may be located inside the cold box 14 or outside the cold box 14.

[0056] In some embodiments, the flow splitter 19 may be incorporated into the first heat exchanger 15 as a heat exchanger flow splitter 15a, an example of which is shown in FIG. Figure 2 For this embodiment, the heat exchanger splitter 15a can split the Xe and / or Kr-rich purge stream 105 while it is undergoing a temperature increase in the first HX 15, so that a first portion 110 of the heated Xe and / or Kr-rich purge stream can be directed to the DPU 21, and a second portion 108 of the heated Xe and / or Kr-rich purge stream can be recycled back to the compression system 101 or a location downstream of the compression system 101 and upstream of the PPU 13, so that the recycled second portion 108 passes through the PPU 13 again for further purification to further remove any CO that may be included therein. 2 or N 2 O. Such embodiments may utilize gasifier 16 ( Figure 2 The recycle stream (shown in dashed line) is used to provide additional heating to the recycle stream to be recycled back to the PPU 13.

[0057] The division of the Xe and / or Kr-rich purge stream 105 or 105a into the first partial stream 110 and the second partial stream 108 can also be adjusted dynamically to take into account process parameters. For example, as the adsorbent material in the PPU 13 loses its useful life, more CO 2 and / or N 2 O may break through downstream of PPU 13. In response to the detection of CO 2 and / or N 2 As the O concentration increases above the first preselected operating value, the Xe and / or Kr-rich purge stream 105 may be adjusted to be split into a first partial stream 110 and a second partial stream 108 so that as the CO 2 and / or N 2 As the O concentration increases beyond the first preselected value, more of the Xe and / or Kr-rich purge stream 105 is recycled. This increase in the amount of Xe and / or Kr-rich purge stream 105 recycled may be based on the detected CO 2 and / or N 2 The concentration of O can be adjusted dynamically to correspond to the specific concentration of CO detected. 2 and / or N 2 The concentration of O reaches or exceeds different preselected thresholds at different increasing levels. For example, the recirculated second portion 108 can be adjusted to a second flow rate greater than the first flow rate in response to the CO 2 and / or N 2 O reaches or exceeds a first preselected value (e.g., increases from an initial flow rate to a first increased flow rate), and then may be further adjusted to a third flow rate greater than the second flow rate in response to CO 2 and / or N 2The O concentration subsequently reaches or exceeds a second preselected threshold value that is higher than the first preselected threshold value (e.g., increases from a first increased flow rate to a second increased flow rate), and in response to the CO 2 and / or N 2 O concentration reaches or exceeds a third preselected threshold value greater than the second preselected threshold value, may be further adjusted to a fourth flow rate greater than the third flow rate (e.g., increasing from the second increased flow rate to the third increased flow rate), etc. This change to the recirculated second portion 108 may result in the first portion 110 of the heated Xe and / or Kr-rich purge stream directed to the DPU 21 decreasing as the flow rate of the second portion 108 increases, so as to increase the portion of the purge stream 105 or 105a that is recycled back to the PPU 13 and / or the flow rate of the portion of the purge stream that is recycled to the PPU 13. The increased portion of the purge stream that is recycled to the PPU 13 may help avoid a decrease in the Xe and / or Kr concentration in the heated Xe and / or Kr-rich purge stream fed to the DPU 21, so that the operating performance of the DPU 21 is not affected by CO that may occur during operation of the device. 2 and / or N 2 The increase of O will substantially degrade or become uneconomical. This can significantly improve the operating performance of the device and increase the design and operation flexibility of the device.

[0058] As described above, the PPU 13 may be configured to remove CO from the pressurized gas stream 102. 2 、N 2 O, CO, H 2 and heavier hydrocarbons (such as butane, ethylene and / or acetylene, etc.). 2 and N 2 O has a very low volatility and trace amounts may still break through the PPU during operation. This can occur especially when the adsorption material of the PPU begins to approach the end of its useful life and when it is close to the time when the online adsorber of the PPU might be scheduled for regeneration operation. 2 and / or N 2 O can break through the PPU and remain in the purified and pressurized gas stream 104 output by the PPU. Due to their low volatility, they may accumulate in the purge stream 105 rich in Xe and / or Kr. Due to the operating temperature of the device 10 and its freezing point, these undesirable components (CO 2 and / or N 2 The presence of CO may freeze, which may cause significant operating problems, such as flow obstruction and possible damage to process components due to freezing. 2 and / or N 2A slight breakthrough of O may still limit the extent to which the Xe and / or Kr rich purge stream 105 may be reduced to increase the Xe and / or Kr concentration in the stream, which may limit the Xe concentration and / or Kr concentration in the Xe and / or Kr rich purge stream 105.

[0059] This problem can be further addressed in a cost-effective manner while also allowing the Xe and / or Kr concentration of the Xe and / or Kr-rich purge stream 105 to be significantly improved by recycling (or dynamically recycling) a portion of the Xe and / or Kr-rich purge stream 105 to the compression system 101 so that this portion can be purified again through the PPU 13 to further remove CO. 2 and N 2 O. To help maximize Xe recovery while also maintaining or improving CO 2 and N 2 To remove O, the PPU 13 may include a small pore zeolite, such as 4A zeolite (also known as NaA zeolite), in at least one front-end adsorber of the PPU for CO 2 and N 2 O removal. The pore size of 4A zeolite is large enough to allow CO 2 and N 2 O is adsorbed therein, but can also be small enough to exclude most of the Xe in the adsorbed fluid, which can achieve a higher Xe recovery rate through the adsorber of PPU 13 and provide a higher Xe concentration in the downstream process of device 10 downstream of PPU 13. This result can further enhance the improvement provided by the adjustable recovery operation of the second part 108 of the purge stream rich in Xe and / or Kr described above.

[0060] The 4A zeolite may be used as a full or partial replacement for the 13X zeolite in the PPU 13. In some embodiments, it is most advantageous to size the 4A zeolite for CO removal. 2 and some N 2 O, while retaining some 13X zeolite to remove trace hydrocarbons and residual N 2 O, as the adsorbent material of PPU 13. In other embodiments, the adsorbent material may not have any 13X zeolite, but may include 4A zeolite to further reduce Xe loss (e.g., up to 10 times). In addition to 4A zeolite, other small pore zeolites may be used, or as substitutes. These other small pore zeolites may include, for example, chabazite, rho, hydrocalcium zeolite or maltite, which have different extra-framework cation combinations. In some of these embodiments, A zeolite may include one or more of the following extra-framework cations: sodium (Na), potassium (K), calcium (Ca) and zinc (Zn).

[0061] We have determined that, as described herein, recycling a portion of the purge stream 105 or 105a, and dynamically adjusting the portion of the purge stream that is recycled to the PPU 13, can provide significant operational and device design improvements in terms of operating and capital costs. In addition, after the Xe and / or Kr content is significantly increased (e.g., more than 100 times or about 500 times, etc.), a portion of such purge stream is recycled to the PPU, and then, by mixing the recycled portion of the purge gas with the compressed feed air or feed air, the increased concentration of the rare gas fluid is recycled to dilute the rare gas component, which is unexpected. This mixing of the recycled portion can cause the concentration of the rare gas component to be reduced back to a level close to its initial low concentration in the feed air. This is traditionally considered undesirable. However, as described herein, the implementation of this design provides surprising improvements in operating efficiency and device design. The embodiments discussed herein can provide device designs and device operating schemes that are contrary to standard practices and protocols in the art to provide surprising improvements in operating efficiency while also allowing for reduced capital costs.

[0062] It will be appreciated that embodiments of the apparatus 10 may include an arrangement in which there is a single DPU 21 that is fed by a combined Xe and / or Kr-rich stream from one or more ASUs. In such embodiments or other embodiments in which multiple ASUs may be utilized, the apparatus 1 may utilize a portion of the Xe and / or Kr-rich purge stream to be recycled to only one of the PPUs of the multiple ASUs or to different PPUs of different ASUs. In such embodiments, the recycle of the Xe and / or Kr-rich stream may be delivered to only one of the PPUs of multiple different ASUs, or there may be multiple recycle streams, each of which is recycled back to a corresponding PPU of a different ASU of the apparatus 10.

[0063] Embodiments of device 10 may utilize a controller to monitor and control the operation of device 10. For example, Figure 1-2 The illustrated embodiment of the apparatus 10, as well as other embodiments explicitly discussed herein, may include a controller, such as Figure 3 The exemplary controller shown may include a temperature sensor, a pressure sensor, a flow sensor, and a concentration sensor (for detecting one or more compounds (e.g., 2 , Ar, CO 2 、N 2 , Xe, Kr, CO, CH 4, water, etc.) is used to sense and / or detect the flow rate, concentration, temperature or pressure of the fluid flowing through different elements or units of the device and / or the pipelines between these units. For example, sensors can be set to detect (i) the air flow rate, pressure, temperature and feed concentration of the air fed to the compression system 101, (ii) the flow rate, pressure, temperature and / or feed concentration of the air output from the compression system 101 fed to the heat exchanger (e.g., the first HX 15), (iii) the flow rate, pressure, temperature and feed concentration of the air output from the heat exchanger for feeding to another device unit, and / or (iv) the flow rate, pressure, temperature and component concentration of the fluid output from the device unit. Other sensors can also be installed in the device 10 to monitor and control the operation of these elements of the device 10. A controller can be provided to receive data from these sensors and adjust the operation of different elements based on the received sensor data. An example of such a controller is Figure 3 As shown, it may include a processor connected to a non-transitory computer-readable medium and at least one interface for communicating with a sensor. The processor may run at least one automatic control program stored in a computer-readable medium (e.g., a non-transitory memory, a flash memory, etc.), which defines a method for controlling the operation of the device and / or one or more elements of the device.

[0064] It should be understood that embodiments of the controller may also be configured to utilize other sensor data to drive different device operations and use different conduits to implement different flow paths for fluids to and from different components. In some embodiments, the controller may be connected to a display and at least one input device and / or input / output device to facilitate outputting data to a user or operator and receiving input from an operator. For example, the controller may be connected to an operator workstation or a device operator's computer. The controller may also be connected to other device control elements to be incorporated into a larger automated method control system for the device.

[0065] We have determined that embodiments of our apparatus 10, air separation processes, and methods of making and using the same can be configured to increase the recovery of xenon (Xe) and / or krypton (Kr), while also allowing the apparatus to be operated at a lower operating cost by reducing the power or energy required for operation, due to improvements that can be provided in purifying the Xe and / or Kr output from the first HX 15 or first separation system 17 for feeding to at least one DPU 21. Moreover, embodiments can provide enhanced operational flexibility to address impurity breakthrough events that may occur during operation of the apparatus 10.

[0066] Embodiments of our improved Xe and / or Kr recovery methods may also include kits that allow existing air separation plants or other types of air separation units to be modified to perform Xe recovery, and / or have improved Xe recovery and / or Kr recovery. For example, some embodiments may provide a kit for a plant operator to upgrade the plant 10 to include a new configuration of a splitter device 19 and / or a heat exchanger and / or a PPU so that the plant can utilize embodiments of our methods to increase the recovery of Xe and / or Kr from the feed gas 100 by increasing the Xe and / or Kr concentration in the stream fed to the DPU 21, and / or improve operating efficiency. The kit may include adjusting the PPU adsorbent material and / or the PPU 13, adjusting the piping of the heat exchanger and / or providing DPU 21 process elements for purifying a purge stream 105 containing Xe and / or Kr to produce at least one product stream containing Xe and / or Kr. The kit provided may allow an operator to recycle a portion of the purge stream 105 containing Xe and / or Kr so that when more CO is detected, the purge stream 105 containing Xe and / or Kr is recycled. 2 and / or N 2 O can also be recycled when passing through the PPU 13 (e.g., including software upgrades for controllers or new controllers, etc.). By including at least one DPU 21, such a kit can help plant operators adjust operations to provide new products, or increase the output and profitability of existing Xe and / or Kr recovery operations.

[0067] It should be understood that the embodiments clearly shown and discussed herein can be modified to meet a set of specific design goals or a set of specific design standards. For example, the arrangement of valves, pipes and other pipeline elements (such as pipeline connection mechanisms, pipelines, seals, etc.) is used for different units of interconnected devices to carry out fluid communication of fluid flow between different units to meet a specific device layout design, which takes into account the available area of ​​the device, the equipment size of the device and other design considerations. For example, the size and configuration of any heat exchanger, adsorber, compressor, tower, pipeline, expander, pump or compressor used in the embodiment can be modified to meet a set of specific design standards. As another example, the flow rate, pressure and temperature of the fluid through one or more heat exchangers and other device elements can be changed to consider different device design configurations and other design standards. As another example, the number of device units and their arrangement can be adjusted to meet a set of specific design standards. As another example, the material composition of the different structural components of the device and the device unit can be any type of suitable material that may need to meet a set of specific design standards.

[0068] It should be understood that embodiments of the apparatus may be configured as an air separation apparatus or other type of apparatus where it is desired to recover nitrogen and / or argon from a feed gas (e.g., air, waste effluent from the apparatus, etc.) The apparatus 10 may be configured to include process control elements positioned and configured to monitor and control operations (e.g., temperature and pressure sensors, flow sensors, an automated process control system having at least one workstation including a processor, non-volatile memory and at least one transceiver for communicating with the sensor elements, valves and controllers for providing a user interface for the automated process control system that may be run on a workstation and / or another computer device of the apparatus, etc.).

[0069] As another example, it is contemplated that the specific features described, whether described separately or as part of an embodiment, can be combined with other separately described features or parts of other embodiments. Therefore, the elements and actions of the various embodiments described herein can be combined to provide further embodiments. Therefore, although certain illustrative embodiments of methods for recovering fluids (e.g., oxygen, argon and / or nitrogen and krypton and / or xenon) from air, gas separation devices configured to recover nitrogen, argon and / or oxygen from at least one feed gas, air separation devices, air separation systems, devices utilizing such systems or methods, and methods of making and using them have been shown and described above, it should be clearly understood that the present invention is not limited thereto, but may be embodied and practiced in other different ways within the following claims.

Claims

1. A method for separating a feed gas comprising oxygen, nitrogen and argon, the method comprising: Purifying the compressed feed gas through a pre-purification unit before feeding the purified and compressed feed gas to the first separation system to form at least one product stream from the feed gas, the at least one product stream comprising a nitrogen stream, an oxygen stream and / or an argon stream; outputting a first purge stream comprising xenon (Xe) and / or krypton (Kr) from the first separation system; and splitting the first purge stream such that a first portion of the first purge stream is directed to at least one downstream processing unit to form a first product stream comprising Xe and / or a second product stream comprising Kr, and a second portion of the first purge stream is directed upstream of the pre-purification unit for additional purification by the pre-purification unit, The pre-purification unit comprises an adsorbent material comprising a zeolite having a pore size configured to receive and adsorb CO2 and N2O therein while excluding a majority of Xe in the compressed feed gas being purified in the pre-purification unit.

2. The method according to claim 1, comprising: In response to a concentration of carbon dioxide (CO2) and / or nitrous oxide (N2O) reaching or exceeding a first preselected threshold, adjusting a split of the first purge stream such that a flow rate at which the first portion of the first purge stream is directed to the at least one downstream processing unit is decreased and a flow rate at which the second portion of the first purge stream is directed to the pre-purification unit is increased such that a portion of the first purge stream that is recycled to the pre-purification unit is increased.

3. The method according to claim 1, comprising: In response to a concentration of carbon dioxide (CO2) and / or nitrous oxide (N2O) in the purified and compressed feed gas reaching or exceeding a first preselected threshold, adjusting the split of the first purge stream such that a portion of the first purge stream directed to the prepurification unit is increased and a portion of the first purge stream recycled to the prepurification unit is increased.

4. The method of claim 1, wherein the adsorbent material comprises 4A zeolite, chabazite, rho, calcite and / or offalite.

5. A method according to claim 1, wherein the diversion of the first purge stream is performed via a valve or a diversion device, so that the first part of the first purge stream is directed to at least one downstream processing unit to form a first product stream containing Xe and / or a second product stream containing Kr, and the second part of the first purge stream is directed upstream of the pre-purification unit for additional purification through the pre-purification unit.

6. The method of claim 5, wherein the valve or the flow diverter device is located outside the cold box.

7. A method according to claim 1, wherein the first purge stream is split by a first heat exchanger located downstream of the pre-purification unit and upstream of the first separation system, so that the first part of the first purge stream is directed to at least one downstream processing unit to form a first product stream containing Xe and / or a second product stream containing Kr, and the second part of the first purge stream is directed upstream of the pre-purification unit for additional purification by the pre-purification unit.

8. The method of claim 7, wherein the first heat exchanger is a first heat exchanger of a cold box.

9. A method according to claim 1, wherein the diversion of the first purge stream is performed outside the cold box or in the cold box, so that the first part of the first purge stream is directed to at least one downstream processing unit to form a first product stream containing Xe and / or a second product stream containing Kr, and the second part of the first purge stream is directed upstream of the pre-purification unit for additional purification through the pre-purification unit.

10. A device for recovering xenon (Xe) and / or krypton (Kr), comprising: A diversion device is positioned to divert a first purge stream containing xenon (Xe) and / or krypton (Kr) output from a first separation system so that a first portion of the first purge stream is directed to at least one downstream processing unit to form a first product stream containing Xe and / or a second product stream containing Kr, and a second portion of the first purge stream is directed upstream of a pre-purification unit, the pre-purification unit is positioned to purify a compressed feed gas for feeding to the first separation system, wherein the pre-purification unit includes an adsorbent material, the adsorbent material includes a zeolite, the pore size of the zeolite is configured to receive and adsorb carbon dioxide (CO2) and / or nitrous oxide (N2O) therein, while excluding most of the Xe in the compressed feed gas.

11. The device according to claim 10, comprising: The pre-purification unit is positioned to receive the compressed feed gas to purify the compressed feed gas, and is used to send the compressed feed gas to the first separation system to form at least one product stream from the feed gas, wherein the at least one product stream includes a nitrogen stream, an oxygen stream and / or an argon stream.

12. The apparatus according to claim 11 comprises the first separation system, which is configured to output the first purge flow comprising Xe and / or Kr and form the at least one product flow comprising the nitrogen flow, the oxygen flow and / or the argon flow.

13. The apparatus of claim 10, wherein the flow diversion device comprises a valve.

14. The apparatus of claim 10, wherein the diversion device is configured to divert the first purge stream so that, in response to a concentration of carbon dioxide (CO2) and / or nitrous oxide (N2O) reaching or exceeding a first preselected threshold, the portion of the first purge stream directed to the at least one downstream processing unit is reduced and the portion of the first purge stream recycled to the pre-purification unit is increased.

15. The apparatus of claim 10, wherein the flow splitting device is configured such that the first purge stream can be split so that in response to the concentration of carbon dioxide (CO2) and / or nitrous oxide (N2O) in the purified and compressed feed gas reaching or exceeding a first preselected threshold, the flow rate of the second portion of the first purge stream directed to the pre-purification unit is increased to a first increased flow rate, such that the portion of the first purge stream recycled to the pre-purification unit is increased.

16. The device of claim 10, wherein the adsorbent material comprises 4A zeolite, chabazite, rho, calcite and / or formosite.

17. The apparatus of claim 12, wherein the flow splitting device is located in a first heat exchanger downstream of the pre-purification unit and upstream of the first separation system.

18. The apparatus of claim 17, wherein the first heat exchanger is a first heat exchanger of a cold box.

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