Air separation equipment, adsorber and method

Abstract

A method for purifying air through a pre-purification unit (PPU) of an air separation unit (ASU) system having a pre-PPU cooler located upstream of the PPU to cool the compressed air before it is sent to the PPU, the method may include the steps of passing air through an adsorber of the PPU to pass the air through a bed of adsorbent material within a vessel of the adsorber. In response to a determination that a problem exists with the pre-PPU cooler that causes the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline, the ASU system should continue to operate at full capacity even if nitrous oxide (N2O) in the air output of the PPU exceeds a first preselected threshold and is below a second preselected threshold associated with carbon dioxide (CO2) breakthrough. The ASU and PPU may be designed to implement embodiments of the method.

Description

Technical Field

[0001] The present invention relates to air separation systems, arrangements of pre-purification units that can be used in such systems, adsorbers for purifying air in air separation systems, and methods of making and using the same. Background Art

[0002] Thermal Swing Adsorption (TSA) is often used in conjunction with technologies such as Pressure Swing Adsorption (PSA) as a pre-cleaning method for cryogenic air distillation processes. TSA removes components with high freezing points, such as ambient moisture (e.g., water vapor, H2O) and carbon dioxide (CO2), which would otherwise freeze in downstream processing, leading to operational issues such as blockages. Nitrous oxide (N2O), hydrocarbons (e.g., methane, CH4), and other impurities can also be removed through front-end purification to prevent their accumulation in downstream processes.

[0003] Purification units typically use adsorbers. There are four common configurations for adsorbers: vertical, vertical crossflow, horizontal, and radial. Examples of these types of adsorbers, TSA systems, and PSA systems can be found in U.S. Patents Nos. 4,472,178, 4,541,851, 4,784,672, 5,137,548, 5,232,474, 5,425,240, 5,759,242, 5,846,295, 5,917,136, 6,086,659, 6,106,593, 6,152,991, 6,506,236, 6,599,347, 6,866,075, 7,022,159, 7,285 ,154, 7,413,595, 8,206,669, 8,262,783, 8,268,044, 8,404,024, 8,518,356, 8,734,571, 8,814,985, 9,108,145, 9,199,190, 9,631,864 and 9,731,241, U.S. Patent Publication Nos. 2011 / 0206581, 2011 / 0219950 and 2019 / 0291078, and Canadian Patent Publication No. 2,357,276A.

[0004] As disclosed in U.S. Patent No. 6,106,593, it is known that nitrogen oxides should be removed from feed air for air separation. One minor air component is nitrous oxide (NO), which is present in ambient air at a concentration of approximately 0.3 ppm. As taught in U.S. Patent No. 6,106,593, NO is believed to have physical properties similar to those of carbon dioxide and is therefore recognized to present potential operational problems due to the formation of solids in the air separation columns and heat exchangers of cryogenic distillation systems that separate air into one or more products (e.g., oxygen, nitrogen, etc.).

[0005] US Patent No. 6,106,593 also discloses that N2O is known to enhance the combustion of organic materials and is shock sensitive. US Patent No. 6,106,593 discloses that N2O is also considered to pose a safety hazard to the operation of cryogenic distillation systems. Summary of the Invention

[0006] We have determined that air separation unit (ASU) systems typically must account for known operational issues associated with the use of chillers to cool compressed air before the air stream is sent to the pre-purification unit (PPU). In conventional ASU systems, cooling of the air is critical to help ensure that the nitrous oxide and carbon dioxide levels in the air stream output from the PPU do not exceed very low preselected thresholds. For example, mechanical chillers often experience multiple equipment failures per year. For example, a mechanical chiller's compressor may fail (e.g., break, stop working, etc.) approximately 1-2 times per year (and sometimes more frequently) during operation. Other types of expected failures may include leaks or blockages in heat exchangers, pump failures in absorption chillers, level sensor failures, actuator failures, control system errors or failures, valve failures, or other types of mechanical failures. Due to this known chiller operational issue, providing redundant chillers as backup chillers typically incurs increased capital costs to address such issues. Alternatively, the ASU system can be designed with a significantly larger PPU, which may be more expensive to construct and may incur higher operating costs due to the omission of a chiller and the higher input operating temperature of the air stream being fed to the PPU. Alternatively, the ASU system can be designed to shut down (operate at less than design power) during a chiller failure and operate with backup liquid product in storage tanks, which has a significant impact on capital costs. These arrangements have been conventionally developed in the art to help ensure that the ASU system 1 does not operate when the CO2 and N2O of the PPU exceed their very low predetermined process ranges, thereby avoiding downstream processing issues that could affect system safety.

[0007] We have determined that the objectives of this safety precautionary action can be achieved while also allowing for improved chiller usage in the ASU system to improve operational efficiency while also maintaining the continued safety of the ASU system's operations. We have determined that it is safe to allow N2O to pass through the ASU system's pre-purification unit (PPU) at elevated levels for a relatively short preselected duration (e.g., no more than 14 days, no more than 7 days, or no more than 2 days, etc.) to account for chiller failures that can be resolved and eliminated within the preselected duration, while also providing significant advantages that can reduce costs and increase profitability while maintaining safe operations. For example, we have determined that allowing N2O to pass through the PPU at elevated levels above a first threshold level for a relatively short duration, while still at a second threshold level associated with CO2 breakthrough, can be allowed to pass through the PPU without creating direct safety or other direct operational issues. In contrast, CO2 breakthrough would create such issues.

[0008] By allowing the ASU system to operate at full capacity during pre-PPU chiller maintenance or other trips of the pre-PPU chiller, the ASU can continue to operate at a higher overall profit and efficiency than if the ASU were shut down or operated at a lower capacity to account for the pre-PPU chiller's operating conditions. We have determined that allowing N2O to break through the PPU at a level exceeding a first preselected operating threshold while still below a second preselected threshold associated with CO2 breakthrough can prevent excessive N2O accumulation in the ASU system without creating issues requiring resolution of a chiller trip condition (e.g., compressor failure, pump failure, etc., which may take 1-14 days to resolve, up to 7 days to resolve, or up to 2 days to resolve) for a relatively short duration. Under these constraints, allowing N2O breakthrough beyond the PPU can avoid severe issues associated with CO2 breakthrough and can be mitigated by adjusting the ASU system's defrost interval to a slightly shorter interval (e.g., 1-4 months shorter, 0.5-5 months shorter, 0.5-2 months shorter, etc.) to account for the duration of the increased N2O levels.

[0009] Because elevated N2O levels do not immediately pose a problem, we determined that the operational tradeoff is to allow N2O to breach the PPU while maintaining tight CO2 control. Furthermore, elevated N2O conditions can be further mitigated during other ASU system operating hours, which can be more beneficial to the ASU system operator without significantly offsetting the operational efficiencies and cost savings gained by allowing the system to operate with limited N2O breakthrough.

[0010] Embodiments of the PPU, ASU systems, and methods can provide additional benefits related to reduced capital costs. For example, embodiments can allow flexibility in whether the chiller is operational, while allowing the PPU vessel size to remain smaller, which impacts capital costs. Traditionally, as the PPU feed temperature increases (such as when a chiller trips), it is often expected that the PPU size must be increased to account for such operating conditions, as more molecular sieve is required to ensure CO2 and N2O removal. An unexpected benefit of embodiments of our ASU systems and methods is that they can also provide operational flexibility and continuity with lower capital costs and the use of less molecular sieve adsorbent material.

[0011] For example, when the ASU system is not operating at elevated N2O levels (e.g., during shutdown and / or winter ambient operating conditions), the system can take corrective actions to help mitigate N2O accumulation that can adversely affect the operating units of the system. For example, the defrost interval of the ASU system can be adjusted to take into account the duration of the impact of elevated N2O on system operation. Such defrost intervals typically occur every few years (e.g., 3-10 years, 3-8 years, 5-8 years, 4-10 years, etc.). Slight adjustments to this interval (e.g., 1-2 months, 0.5-1 month, 0.5-4 months, etc.) may have a negligible impact on the cost and efficiency gains associated with operating the ASU system at elevated N2O levels, taking into account the periodic operation of the chiller located upstream of the PPU, which is used to cool the compressed feed air to the PPU to remove undesirable impurities from the air.

[0012] As a specific, non-limiting example that helps illustrate the novel trade-offs we have determined to be feasible for embodiments of our method, our PPU, and ASU system, an ASU system may be designed to process 3,000 tons of oxygen per day. In such a system, a chiller trip resulting in operation at excessively high NO levels for up to 8 days may be permitted, wherein 50% of the ambient NO in the compressed air supplied to the PPU is allowed to break through the PPU and escape into the ASU, and result in an adjustment of the defrost interval to account for this NO increase over the 8-day period of operation. For this particular non-limiting example, such an adjustment may shorten the defrost interval by approximately 24 days (e.g., requiring the defrost sequence to be performed 24 days faster). In other examples, an ASU system designed for a 3-year or 5-year defrost interval, operating at excessively high NO levels for up to 8 days, wherein 50% of the ambient NO in the compressed air supplied to the PPU is allowed to break through the PPU and escape into the ASU, may result in a reduction in the defrost interval adjustment by 16 days or 30 days, respectively.

[0013] It will be appreciated that the defrost interval is the period of time that the ASU may operate continuously between defrost operations (e.g., the period of time between a first defrost operation performed on the ASU and a subsequent second defrost operation performed on the ASU). For example, if the defrost interval is, for example, three years, then three years will separate the first and second defrost intervals, and no other defrost operations will be performed during the three years between the first and second defrost operations. As another example, if the defrost interval is five years, then five years will separate the first and second defrost intervals, and no intervening defrost operations will be performed during the five-year defrost interval.

[0014] We have determined that embodiments can provide significant operational improvements and improved operational flexibility because the defrost interval can be timed by the operator to account for operator convenience and avoid unnecessary costs associated with redundant chillers, larger PPU designs, or unexpectedly taking the ASU system offline to account for unplanned chiller trips. Adjustment of the defrost interval can allow the ASU system to safely operate at high N2O levels for one or more time periods, each within a predetermined time period. The ASU system can be configured to monitor for excess N2O and CO2 accumulation to further enhance the safety of ASU system operation and facilitate safe adjustment of the defrost interval, which may require shortening due to ASU operation at high N2O levels.

[0015] We have determined that embodiments of our ASU system, PPU, and adsorber can provide significant advantages. For example, embodiments of the adsorber can enable reliable and uninterrupted operation of the ASU system despite a chiller trip. A chiller trip can occur when a pre-PPU chiller experiences a failure that may require the chiller to be taken offline (e.g., bypassed so that it is no longer in operation) or to be operated at a reduced load.

[0016] Examples of chiller trips may include pump failure, compressor failure, heat exchanger leaks (e.g., evaporator leaks, generator leaks, etc.), chiller conduit blockages, valve failures, pump failures, level sensor failures, actuator failures, control system errors or failures, or other types of mechanical failures. Such failures may be associated with reduced chiller performance, which prevents the chiller from cooling the compressed air output of the compressor system to within the desired preselected PPU feed temperature range, which may adversely affect the effectiveness of the PPU in being able to adsorb impurities such as N2O and / or CO2.

[0017] As another example, embodiments of the adsorber can utilize smaller molecular sieve layers of adsorbent material to remove N2O, which can significantly reduce the size of the adsorber required for the PPU. This can improve operating efficiency and reduce the overall capital cost, maintenance cost, and operating cost of a PPU using such an adsorber. Embodiments of our PPU (using embodiments of our adsorber) can also eliminate the need for cooler redundancy in the ASU system's pre-PPU cooler, which is located upstream of the PPU and used to cool the air delivered to the PPU. Avoiding the need for backup coolers to be online when an online cooler has a problem or requires maintenance can significantly reduce the capital cost of the system and reduce the floor space required for such a system. In some types of facilities, this can provide significant capital cost savings because additional coolers and the installation of redundant coolers can be avoided. In some large ASU systems, such cost savings can be as high as $500,000 or several million yuan. In some small and medium-sized ASU systems, the cost savings can be between $100,000 and $400,000.

[0018] Embodiments of the PPU and adsorber can also allow the ASU system to operate without a specialized NO removal layer, which typically requires a higher temperature regeneration gas compared to other adsorbent materials with lower adsorbent material regeneration temperatures. For example, embodiments of our adsorber can avoid the use of a layer of CaX adsorbent material, which can require the use of regeneration gas at a temperature of 300°C or higher and can be 30% more expensive than some types of adsorbent material (e.g., NaMSX adsorbent material). Thus, such embodiments can provide lower operating costs by requiring a lower temperature regeneration gas stream.

[0019] In some embodiments, each adsorber of the PPU may have a single layer of material for its adsorption material bed, the adsorption material including a molecular sieve material (e.g., 13, NaX, NaMSX, alumina, silica gel, combinations thereof, such as physical mixtures, and composite adsorbents containing alumina and molecular sieves, etc.), which is used to remove 95%-100% of water or 99%-100% of water, 95%-100% of CO2 or 99%-100% of CO2, and 50%-100% of N2O or 95-100% of N2O in the air delivered to the PPU when the cooler is operating normally, and to remove 95%-100% of water or 99%-100% of water, 95-100% of CO2 or 99%-100% of CO2, and 20%-50% of N2O in the air delivered to the PPU when the cooler is tripped, offline, or operating at reduced load.

[0020] In some embodiments, the adsorber can be configured to remove 20%-50% or 10%-50% of the N2O in the air delivered to the PPU when the chiller is in a tripped state, or less than 50% of the N2O in the air delivered to the PPU. For example, if the N2O content in the air delivered to the PPU is 0.4 ppm, the N2O content in the cleaned air output of the PPU can be in the range of 0.25 ppm to 0.2 ppm N2O, in the range of 0.25 ppm to 0.32 ppm N2O, in the range of 0.3 ppm to 0.25 ppm N2O, or in the range of 0.2 ppm to 0.32 ppm N2O. In such embodiments, when the chiller is operating normally, the N2O content in the air output of the PPU can be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.2 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0021] As another example, if the NO content in the air delivered to the PPU is 0.3 ppm, when the chiller is operating in a tripped condition, the NO content in the clean air output of the PPU may be in the range of 0.15 ppm to 0.0675 ppm NO, in the range of 0.15 ppm to 0.3 ppm NO, in the range of 0.15 ppm to 0.24 ppm NO, or in the range of 0.27-0.15 ppm NO. In such embodiments, when the chiller is operating normally, the NO content in the air output of the PPU may be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.15 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0022] Embodiments of the PPU and adsorber can allow the ASU system to operate at full capacity during an upstream pre-PPU cooler failure or pre-PPU cooler trip. This can help avoid the need to use redundant chillers to cool the compressed air being fed to the PPU. This operational flexibility allows for lower capital, operating, and maintenance costs, while providing better output for the ASU system 1. Consequently, the overall profitability of an ASU system operator can be significantly improved by utilizing embodiments of an ASU system utilizing a PPU with an absorber employing our adsorber embodiments.

[0023] An embodiment of an adsorber of a pre-purification unit (PPU) of an air separation unit (ASU) system may include a vessel connectable between a compressor system and a heat exchanger, and a bed of adsorbent material disposed within the vessel. The bed of adsorbent material may be configured to remove water (H2O) and carbon dioxide (CO2) from a compressed air stream fed to the PPU, and may also be configured to remove nitrous oxide (N2O) such that the N2O in an air output from the PPU is below a first preselected threshold. The bed of adsorbent material may be configured such that, in response to a determination that a problem exists with a pre-PPU cooler that causes the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline, the PPU may be operated at full capacity such that the N2O in the air output from the PPU exceeds the first preselected threshold and is below a second preselected threshold associated with CO2 breakthrough.

[0024] The first layer of adsorbent material may comprise a specific type of material or a combination of materials. In some embodiments, for example, the first layer may comprise aluminum oxide. The second layer of adsorbent material may also comprise a specific type of material or a combination of materials. In some embodiments, for example, the second layer of adsorbent material may comprise NaX, NaLSX, or NaMSX. In some embodiments, the bed of adsorbent material may be constructed as a single layer of material or multiple layers of material.

[0025] The first preselected threshold range and the second preselected threshold range can be different and can be various acceptable ranges that can meet a particular set of design criteria. For example, the first preselected threshold can be in the range of 0-0.2 ppm NO, and the second preselected threshold can be in the range of 0.2-0.32 ppm NO, or in the range of less than 0.4 ppm NO and greater than 0.2 ppm NO. In some embodiments, the first preselected threshold can be selected so that 20%-100% of the NO in the air delivered to the PPU is removed from the air, and the second preselected threshold can be selected so that less than 50% of the NO in the air delivered to the PPU is removed from the air.

[0026] Also provided herein is a method for purifying air through a PPU of an ASU system having a pre-PPU cooler located upstream of the PPU for cooling the compressed air before delivering it to the PPU. Embodiments of such a method may include passing air through an adsorber of the PPU so that the air passes through a bed of adsorbent material within an adsorber vessel, and in response to determining that the pre-PPU cooler has a problem that causes the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline, continuing to operate the ASU system at full capacity even if nitrous oxide (N2O) in the air output of the PPU exceeds a first preselected threshold and is below a second preselected threshold associated with carbon dioxide (CO2) breakthrough.

[0027] The adsorbent material bed may comprise one or more materials. For example, the bed may comprise alumina, silica gel, 13X, NaX, NaLSX, NaMSX, or a combination thereof, with a particle size ranging from 1.0 millimeter (mm) to 5 mm. Other embodiments may utilize other types of bed materials or other types of particle size ranges.

[0028] Embodiments of the method may include other steps. For example, an embodiment may include monitoring the CO2 content in the air output from the PPU. As another example, an embodiment may include taking remedial action to address excess N2O in the air output from the PPU after a pre-PPU cooler of the ASU system is back online and the N2O in the air output from the PPU no longer exceeds a first preselected threshold. The remedial action may be taken immediately after the pre-PPU cooler is back online, or other types of actions may be taken months or years after the pre-PPU cooler is back online. For example, the remedial action may include shortening the defrost interval of the ASU system to account for the duration that the ASU system operated with the N2O in the air output from the PPU exceeding the first preselected threshold. The step of shortening the defrost interval may include reducing the amount of time before the ASU system is scheduled to be defrosted.

[0029] As described above, the first and second preselected threshold ranges can be selected to meet a particular set of design criteria. For example, the first preselected threshold can be in the range of 0-0.2 ppm NO, and the second preselected threshold can be in the range of 0.2-0.32 ppm NO, or another suitable range. As another example, the first preselected threshold can be selected to remove 20%-100% of NO from the air delivered to the PPU, and the second preselected threshold can be selected to remove less than 50% of NO from the air delivered to the PPU.

[0030] Embodiments of the method may be implemented to allow the ASU system to continue operating at full capacity for a preselected duration even if the N2O in the air output of the PPU exceeds a first preselected threshold and is below a second preselected threshold associated with CO2 breakthrough. For example, the preselected duration may be a period of no more than 14 days, no more than 7 days, or no more than 2 days.

[0031] It should be appreciated that even if the N2O in the air output by the PPU exceeds the first preselected threshold, the ASU system can continue to operate at full capacity without operating a redundant pre-PPU cooler to cool the compressed air before it is sent to the PPU to replace the pre-PPU cooler (which determines that there is a problem that causes the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline). Thus, embodiments can be implemented without the use of redundant pre-PPU coolers that must be included in the plant or ASU system.

[0032] Embodiments of an ASU system may include a PPU connectable to a compressor system to receive compressed air from the compressor system. The PPU may be connected to a heat exchanger to deliver air purified by the PPU to the heat exchanger. A pre-PPU cooler may be positioned between the compressor system and the PPU to cool the compressed air output from the compressor system and deliver the cooled compressed air to the PPU. The PPU may include at least one embodiment of an adsorber (e.g., the adsorber described above). For example, the PPU may include a container connectable between the compressor system and the heat exchanger. A bed of adsorbent material may be positioned within the container. The bed of adsorbent material may include at least one layer of adsorbent material to remove water, CO2, and N2O from the air, such that the N2O content of the air output from the PPU is below a first preselected threshold. The ASU system may be configured to operate at full capacity in response to a determination that a problem with the pre-PPU cooler has caused the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline, even if the N2O content of the air output from the PPU exceeds a first preselected threshold.

[0033] Embodiments of the ASU system may include other components.For example, the ASU system may also include an air separation tower assembly positioned to receive air from the heat exchanger.

[0034] Embodiments of the ASU system may be configured such that, in response to a determination that a problem exists with the pre-PPU cooler that causes the pre-PPU cooler to trip, even if N2O in the air output of the PPU exceeds a first preselected threshold, the ASU system may continue to operate at full capacity until the air output of the PPU exceeds a second preselected threshold that is greater than the first preselected threshold. The second preselected threshold may be associated with a CO2 breakthrough condition. In some embodiments, the first preselected threshold may be in the range of 0-0.2 ppm N2O, and the second preselected threshold may be in the range of 0.2-0.32 ppm N2O or in the range of less than 0.4 ppm N2O and greater than 0.2 ppm N2O. In other embodiments, the first preselected threshold may be selected so as to remove 20%-100% of the N2O from the air delivered to the PPU, and the second preselected threshold may be selected so as to remove less than 50% of the N2O from the air delivered to the PPU. In still other embodiments, the first and second preselected thresholds may be set to other values ​​to accommodate a particular set of design criteria.

[0035] Embodiments of the ASU system can be configured to operate at full capacity even if the N2O in the air output of the PPU exceeds a first preselected threshold and remains below a second preselected threshold associated with CO2 breakthrough for a preselected duration. This time period can be, for example, no more than 14 days, no more than 7 days, or no more than 2 days.

[0036] Embodiments of the ASU system can be configured to operate the ASU system at full capacity even if the NO in the air output of the PPU exceeds a first preselected threshold, without operating a redundant pre-PPU cooler to cool the compressed air of the compressor system before delivering the compressed air to the PPU to replace a pre-PPU cooler that is determined to have a problem that causes the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline. For example, the ASU system can be used without using a redundant backup pre-PPU cooler.

[0037] Additional details, objects, and advantages of our air separation systems, adsorbers, radial adsorbers, prepurification systems using one or more adsorbers, and methods of making and using the same will become apparent as the following description of certain exemplary embodiments thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Exemplary embodiments of air separation systems, adsorbers, radial adsorbers, pre-purification systems using one or more adsorbers, and methods of making and using the same are illustrated in the drawings accompanying this document. It should be understood that like reference numerals used in the drawings identify like components.

[0039] Figure 1 FIG2 is a block diagram of a first exemplary embodiment of an air separation unit (ASU) system 1 utilizing an exemplary embodiment of a pre-purification system 3 that purifies an air stream for delivery to an air separation column assembly 5 for separation of the air into oxygen and / or nitrogen streams and other streams (e.g., at least one waste stream and / or argon and / or krypton and / or xenon, etc.). In some embodiments, the ASU system 1 may be a plant or may be used in a plant.

[0040] Figure 2 Schematic diagram of a first exemplary embodiment of a pre-purification unit 107 of a pre-purification system 3 of a first exemplary embodiment of an ASU system 1 .

[0041] Figure 3 is a schematic diagram of a first exemplary embodiment of an adsorber 200 , which may be included in the pre-purification unit 107 of the pre-purification system 3 of the first exemplary embodiment of the ASU system 1 .

[0042] Figure 4 is a schematic diagram of a second exemplary embodiment of an adsorber 200 , which may be included in the pre-purification unit 107 of the pre-purification system 3 of the first exemplary embodiment of the ASU system 1 .

[0043] Figure 5 FIG. 1 is a schematic diagram of a third exemplary embodiment of an adsorber 200 that may be included in the prepurification unit (PPU) 107 of the prepurification system 3 of the first exemplary embodiment of the ASU system 1 .

[0044] Figure 6 is a block diagram of an exemplary controller that may be used in the first exemplary embodiment of the ASU system 1 .

[0045] Figure 7 A flow chart of an exemplary method for purifying air through a PPU of an air separation unit system having a pre-PPU cooler upstream of the PPU to cool the compressed air before sending it to the PPU.

[0046] Figure 8 is a block diagram of an exemplary pre-PPU cooler 104 that may be used in the first exemplary embodiment of the ASU system 1 and may also be used in Figure 9 The pre-PPU cooler 104 is shown as an exemplary cooling medium chilling system (CMCS).

[0047] Figure 9 is a block diagram of an exemplary pre-PPU cooler 104 that may be used in the first exemplary embodiment of the ASU system 1 . DETAILED DESCRIPTION

[0048] refer to Figures 1 to 9 , a plant may include an air separation unit (ASU) system 1. The ASU system 1 may be configured as a cryogenic air distillation system to produce one or more output streams to provide one or more desired products (e.g., oxygen and / or liquid oxygen and / or nitrogen and / or liquid nitrogen and / or argon and / or liquid argon and / or other fluid streams, etc.). In some embodiments, the ASU system 1 may be a plant. In other embodiments, the plant may include the ASU system 1 as a component of a larger facility. For example, a plant including the ASU system 1 may be an industrial power plant, a large manufacturing facility, or other type of plant. Embodiments of the plant or ASU system 1 may utilize a controller to help monitor and / or control the operation of the plant and / or ASU system 1.

[0049] The ASU system 1 can be configured to include a pre-cleaner system 3 for cleaning an incoming air stream to remove impurities from the air for delivery to an air separation column assembly 5 for separation of the air into one or more fluid product streams and one or more waste streams. The one or more product streams can include at least one nitrogen stream and / or at least one oxygen stream, and can also include one or more streams of argon, xenon, krypton, or other air components. The air separation column assembly 5 can also output one or more waste streams. The waste streams can be discharged to the atmosphere and / or used in one or more other plant processes.

[0050] The air separation column assembly 5 can include a multi-column assembly 111, which includes a low-pressure column 111a located above a high-pressure column 111b. In a multi-column arrangement, a reboiler condenser 111c can be located between the high-pressure column 111b and the low-pressure column 111a. The high-pressure column 111b can be considered the first column of the multi-column assembly, operating at the highest pressure of the columns in the multi-column assembly. For example, the high-pressure column 111b can operate at a pressure higher than the operating pressure of the low-pressure column 111a, which can be considered the second column of the multi-column assembly.

[0051] In some embodiments, the low-pressure column 111a may operate at a pressure between 1.1 atm and 5 atm, between 1.1 atm and 3 atm, or greater than 1 bar and less than 5 bar, and the high-pressure column 111b may operate at a pressure between 4.5 atm and 15 atm, or greater than 4 bar and less than 15 bar.

[0052] like Figure 1 As best shown, an inlet air stream 100 may pass through a compressor system 103 to compress the air to a higher, preselected pressure. The pressurized air may be output from the compressor system 103 and delivered via a compressed air feed conduit to a pre-purification unit (PPU) 107 of the pre-purification system 3. The PPU 107 may be configured to purify the compressed air output stream of the compressor system 103 to remove impurities from the air. For example, the PPU 107 may be configured as an adsorption system designed to remove undesirable impurities from the air, such as carbon dioxide (CO2), carbon monoxide (CO), water (H2O), hydrocarbons (e.g., butane, ethylene, etc.), and nitrous oxide (N2O).

[0053] Pre-PPU cooler 104 may be located between compressor system 103 and PPU 107 to cool the compressed air to a preselected PPU temperature or a temperature within a PPU temperature range before delivering the compressed air to PPU 107. Pre-PPU cooler 104 may be (or include) a chiller, a mechanical chiller, an absorption chiller, or other types of coolers. It should be understood that a chiller may also be referred to as a chiller.

[0054] The temperature of the compressed air output from the compressor system 103 can be in the range of 10°C-25°C, 15°C-30°C, or 5°C-50°C. The pre-PPU cooler 104 can be used to cool the compressed air stream to a preselected PPU feed temperature, which is within the PPU feed temperature range of 5°C-15°C, 5°C-20°C, or 10°C-20°C. The cooled compressed air delivered to the PPU can be at this cooled temperature or temperature range. When the pre-PPU cooler 104 is tripped and the pre-PPU cooler is offline or operating at a reduced load, the compressed air delivered to the PPU 107 can be delivered to the PPU at a temperature above the range. For example, when the pre-PPU cooler 104 is tripped (e.g., due to mechanical failure, compressor failure, pump failure, leak, blockage, etc. as described herein), the compressed air can be delivered to the PPU 107 at a temperature within the range of 10°C-25°C, 15°C-30°C, or 5°C-50°C.

[0055] Figures 8 and 9 An exemplary pre-PPU cooler 104 that may be used in the ASU system 1 is illustrated. The pre-PPU cooler may receive an output stream of compressed air 104a from the compressor system 103 and output a cooled compressed air stream 104b for delivery to the PPU 107. It should be understood that other types of absorption chillers or mechanical chillers (e.g., multi-stage absorption chillers, other types of single-stage absorption chillers, single-stage or multi-stage mechanical chillers, etc.) may also be used. Figures 8 and 9 The pre-PPU cooler 104 may include a condenser, a generator, a pump (e.g., at least one pump), a pressure reducing device (e.g., a pressure relief valve), an absorber, and an evaporator. Embodiments may also utilize a first pump, and a second pump may operate in parallel with the first pump or be provided as a secondary pump that can be brought online when the first pump is offline due to a failure, error, or maintenance.

[0056] As from Figure 8 As will be apparent from the exemplary embodiments of the present invention, the chiller 104 can be configured to pass at least one ASU system process stream or other plant stream (process stream) to the generator of the pre-PPU chiller 104. For example, the ASU system process stream can be low-pressure steam (e.g., steam at a pressure of 8-10 bar, or steam at a pressure of or less than 10 bar, steam at a pressure of 800 kPa to 1000 kPa, or steam at a pressure of or less than 1000 kPa, etc.), hot liquid water (e.g., heated but liquid water), or another fluid stream that is part of the ASU system 1, or a waste stream (e.g., heated gas from a gasifier, etc.). In still other embodiments, the process stream passed to the generator of the chiller 104 can be medium-pressure steam or high-pressure steam that is output as a waste stream.

[0057] The pre-PPU cooler 104 can be positioned so that the generator outputs high-pressure refrigerant vapor (HP REFRIGERANT VAPOR) to the condenser to condense the condenser medium inlet fluid (CM-IN) sent to the condenser, thereby condensing the refrigerant. The refrigerant can be water, ethylene glycol, or other suitable refrigerant. The condenser medium can be water, ambient air, or other types of fluids used to condense the refrigerant vapor. The condensed condenser medium can be output from the condenser (CM OUT) for delivery to another plant unit of the ASU system 1 (e.g., a scrubber or reservoir if the cooling medium is water). When the high-pressure refrigerant vapor passes through the condenser, it can be condensed into a liquid and output as high-pressure refrigerant liquid (HP REFRIGERANT LIQUID). The high-pressure refrigerant liquid can then be sent to a pressure reducing device to reduce the pressure of the refrigerant so that low-pressure refrigerant liquid (LP REFRIGERANT LIQUID) can be delivered to the evaporator of the cooler 104. The low-pressure refrigerant can be evaporated in the evaporator. When the refrigerant absorbs heat from the compressed air 104a stream to be cooled by the cooler or the cooling medium stream of the chiller used to cool the compressed air, the refrigerant also flows through the evaporator in a parallel or countercurrent manner with the refrigerant passing through the evaporator. The compressed air 104a stream cooled in the evaporator can be output as a cooled compressed air stream 104b from the evaporator to be sent to the PPU 107. The cooled cooling medium stream of the evaporator can be a cooled cooling medium stream (CMC).

[0058] The LP REFRIGERANT VAPOR output of the evaporator may be sent to an absorber. The absorber may receive a LP CONC. SOLUTION so that the LP CONC. SOLUTION absorbs the LP REFRIGERANT VAPOR, so that the absorber may output a LP DILUTE SOLUTION of the refrigerant for sending to a first pump or a second pump (e.g., Figure 8 The pump shown) is used to form a high pressure dilution solution (HP DILUTE SOLUTION) and is sent to the generator.

[0059] The generator can be used to form high-pressure refrigerant vapor from a high-pressure dilute solution it receives via a pump, using heat from at least one process stream. The generator can also output a high-pressure concentrated solution (HPCONC.SOLUTION) for delivery to a pressure reducer, which can then deliver a low-pressure concentrated solution (LPCONC.SOLUTION) to an absorber as part of a chiller refrigerant circuit.

[0060] It should be understood that the evaporator of the pre-PPU cooler 104 can be arranged and configured as a single-stage cooler or a multi-stage cooler. For example, the pre-PPU cooler 104 can be a multi-stage cooler having additional stages for cooling other process streams in the ASU system 1. As another example, the pre-PPU cooler can be a single-stage or multi-stage cooler that cools the output stream of compressed air 104a in multiple stages before outputting the cooled compressed air stream 104b to the PPU 107.

[0061] As described herein, the pre-PPU cooler 104 may include a direct contact cooler (DCAC) that receives cooled water or other cooling medium from a cooling medium chilling system (CMCS) for contact with an output stream of compressed air 104a to cool the air and output a cooled compressed air stream 104b to the PPU 107. Figure 8 An example of a CMCS is shown. A mechanical cooler can also be used as a CMCS.

[0062] In embodiments where the pre-PPU cooler 104 may include a direct contact chiller (DCAC) that receives chilled water or other cooling medium from a cooling medium cooling system (CMCS), the evaporator of the pre-PPU cooler 104 may cool the warm water or other cooling medium (CMW) of the direct contact chiller (DCAC) of the pre-PPU cooler 104 to cool the cooling medium before it is recycled for reuse in the direct contact chiller of the pre-PPU cooler 104. The cooled cooling medium (CMC) may be output from the cooling medium cooling system (CMCS) of the pre-PPU cooler 104.

[0063] The pre-PPU cooler 104 can be designed so that the temperature difference of the cooler can meet a specific set of process design standard parameters. These parameters can be set as needed based on process conditions (such as the ambient temperature of the feed air received at the compression system 103, the CO2 concentration of the feed, etc.). The pre-PPU cooler 104 can be configured to receive an output stream of compressed air 104a, which can be at a first precooler temperature (e.g., a temperature in the range of 5°C-50°C or 10°C-25°C, etc.), and output a cooled compressed air stream 104b to be sent to the PPU 107 at a first preselected PPU temperature (e.g., a temperature in the range of 5°C-20°C, 5°C-15°C, or 10°C-20°C, etc.).

[0064] The purified compressed air may be output from the PPU 107 and sent to the main heat exchanger 109 via a heat exchanger feed conduit. Before being sent to the main heat exchanger 108, the purified compressed air may be sent from the PPU 107 to a booster compressor 108 to further compress at least a portion of the purified compressed air output from the PPU 107 to a higher pressure. In such embodiments, the entire compressed purified air output from the PPU 107 may be further compressed, or the flow may be split such that a first portion of the compressed purified air output from the PPU 107 is sent directly to the main heat exchanger 109, while a second portion of the air output from the PPU 107 is sent to the booster compressor for further compression to a higher pressure before the second portion is sent to the main heat exchanger 109. The booster compressor feed conduit and the booster compressor output conduit may be arranged to facilitate the transfer of fluid from the PPU 107 to the booster compressor 108, as well as the output of additional compressed air from the booster compressor 108 to the main heat exchanger 109.

[0065] In other embodiments, booster compressor 108 may not be used, and the entire air output of PPU 107 may be sent to main heat exchanger 109 via the main heat exchanger feed conduit.

[0066] The main heat exchanger 109 can be used to cool the compressed purified air. Cooling can be performed via one or more fluid output streams from the air separation column assembly 5. For example, one or more nitrogen and / or oxygen fluid streams can be output from the air separation column assembly 5, so that one or more fluid streams pass through the main heat exchanger 109 and serve as a cooling medium for cooling the compressed purified air. The fluid streams from the air separation column assembly 5 can include at least one nitrogen stream and at least one oxygen stream (e.g., a liquid oxygen stream (LOX)). These fluid output streams from the air separation column assembly 5 can be heated by the compressed purified air as they pass through the main heat exchanger 109. For example, in embodiments where a LOX stream is fed to the main heat exchanger 109 as the cooling medium, the LOX stream can be heated and output from the main heat exchanger 109 as a gaseous oxygen stream (GOX).

[0067] The cooled air can be output from main heat exchanger 109 and delivered to air separation column assembly 5 via at least one air separation column assembly feed conduit. A first portion of the compressed, purified air can be delivered to high-pressure (HP) column 111b of air separation column assembly 5. A portion of the first portion can be separated to form a third portion of feed air. This third portion can be output from main heat exchanger 109 and delivered to expander 110 to reduce the pressure and temperature of the third portion. The third portion of air can then be delivered from expander 110 to low-pressure (LP) column 111a of air separation column assembly 5.

[0068] The second portion of the compressed, purified air (which may be further compressed via booster compressor 108) may be output from the main heat exchanger and also sent to LP column 111a. Of course, in embodiments where booster compressor 108 is not used, the second portion of air may not be present. In such embodiments, if a third portion of air is used that is separated from the first portion of the compressed, purified air sent to main heat exchanger 109 and sent to expander 110, the third portion may be considered the second portion of air rather than the third portion.

[0069] HP column 111b can be positioned and configured to process a cooled first portion of the purified and pressurized air fed to HP column 111b to form a first HP nitrogen-rich vapor stream fed to first reboiler condenser 111c. In some embodiments, the HP nitrogen-rich vapor stream can comprise 100-99 volume percent (vol%) nitrogen, or at least 95 vol% nitrogen.

[0070] HP tower 111b may also form a first HP oxygen-rich stream. The HP oxygen-rich stream may be a liquid, a vapor, or a combination of liquid and vapor. In some embodiments, the HP oxygen-rich stream may comprise 30-40% by volume oxygen, 1-3% by volume argon, and the remainder nitrogen (e.g., 69-57% by volume nitrogen).

[0071] The first HP nitrogen-rich vapor stream may be passed to reboiler condenser 111c to form an HP condensate stream, which may be divided into a plurality of portions via a conduit arrangement including at least one valve or other flow dividing mechanism. For example, a first portion of the HP condensate stream may be output from first reboiler condenser 121 and subsequently recycled back to HP column 111b as an HP reflux stream via an HP reflux stream conduit.

[0072] A second portion of the HP condensate stream can be output from reboiler condenser 111c and subsequently passed to subcooler 115 via a subcooler feed conduit. Subcooler 115 can be a heat exchanger that can cool the second portion of the HP condensate stream, thereby bringing the second portion to a lower temperature suitable for passing as nitrogen-rich LP feed to LP column 111a via a nitrogen-rich LP feed conduit extending from subcooler 115 to LP column 111a. The second portion of the HP condensate stream can be depressurized for passing to the LP column (e.g., via a valve in the nitrogen-rich LP feed conduit extending from subcooler 115 and / or via a depressurization mechanism included in the conduit). The nitrogen-rich LP feed can be a substantially nitrogen-rich liquid feed (e.g., completely liquid, at least 90% liquid by volume, at least 80% liquid by volume, etc.).

[0073] The first HP oxygen-rich stream may be sent to a subcooler 115 (not shown) for cooling. Alternatively, the first HP oxygen-rich stream may forgo such cooling via the subcooler 115. In some embodiments, the first HP oxygen-rich stream may pass through an HP oxygen-rich stream conduit extending from the HP column 111b, the conduit being configured such that the HP oxygen-rich stream output of the HP column 111b may be reduced in pressure via a pressure reducing mechanism (e.g., an expander, a valve, etc.) and then sent to the LP column 111a as a substantially liquid oxygen-rich feed to the LP column 111a.

[0074] Reflux for LP column 111a may be provided via a nitrogen-rich LP feed fed to LP column 111a via a nitrogen-rich LP feed conduit extending from subcooler 115 to LP column 111a. As described above, this nitrogen-rich LP feed may be formed from a second portion of the HP condensate stream output from reboiler condenser 111c. Additional liquid may be provided via one or more of the oxygen-rich feeds fed to LP column 111a.

[0075] Rising vapor, or column boil of LP column 111a, may also be formed via reboiler condenser 111c and may be sent to LP column 111a such that the vapor (or gas) within LP column 111a flows countercurrently to the liquid being sent to LP column 111a (e.g., as rising vapor flows upward in LP column 111a, nitrogen-rich LP feed flows downward, etc.).

[0076] LP column 111a can be operated to output a plurality of separate fluid streams. Some of these fluid streams can be considered waste streams (e.g., at least one nitrogen-rich waste stream), which can be primarily composed of nitrogen gas and / or nitrogen liquid. For example, LP column 111a can be operated to output an overhead steam waste stream and a first LP oxygen-rich liquid stream. In at least some embodiments, LP column 111a can also output an overhead nitrogen-rich steam output stream (not shown), a first argon-rich steam stream (not shown), and one or more other output streams.

[0077] An upper steam waste stream may be output from LP column 111a and passed to subcooler 115 to serve as a cooling medium for cooling a second portion of the HP condensate stream output from reboiler condenser 111c and passed via a subcooler feed conduit to subcooler 115. Subsequently, a waste steam stream may be output from subcooler 115 and passed to main heat exchanger 109 to serve as a cooling medium therein before being output from main heat exchanger 109 as a waste stream that may be vented to the atmosphere or otherwise used in a plant to which the ASU system 1 may be connected (e.g., mixed with flue gas or passed through another heat exchanger for subsequent use in the plant, etc.).

[0078] The first LP oxygen-rich liquid stream output from LP column 111a may be sent to pump 117 to increase the pressure of the stream and then to main heat exchanger 109 as a cooling medium. In some embodiments, the heated oxygen-rich stream may be output from the main heat exchanger as a GOX stream.

[0079] like Figure 2 As best shown, the PPU 107 of the pre-purification system 3 may include a plurality of adsorbers 200. Each adsorber 200 of the PPU 107 may include a layer of adsorbent material that can remove a plurality of target elements (e.g., catalytic materials) from the compressed air delivered to the PPU 107 via absorption. The adsorbers of the PPU 107 may include a first adsorber 107a and a second adsorber 107b. The first and second adsorbers 107a and 107b may be configured as radial adsorbers, vertical adsorbers, vertical cross-flow adsorbers, or horizontal adsorbers, respectively. In some arrangements, the radial adsorbers may be configured such that the feed stream enters from the bottom or adsorber vessel and the output stream exits from the top or vessel, or the feed stream enters from the bottom or vessel and the output stream exits from the bottom of the vessel. The PPU 107 may utilize an arrangement of the adsorbers 200 so that they are configured to utilize a temperature swing adsorption process and / or a pressure swing adsorption process.

[0080] The first and second radial adsorbers 107a and 107b can be arranged within the PPU 107 so that they operate in parallel. While the first adsorber 107a is online performing a purification process by adsorbing the target material from the air supplied to the PPU 107, the second adsorber 107b can be offline for purification so that it can be thermally regenerated to regenerate the bed 221 of the adsorbent material in the adsorber 200.

[0081] While the second adsorber 107b is performing a purification process online by adsorbing a target material from air supplied to the PPU 107, the first adsorber 107a can be taken offline for purification so that it can be thermally regenerated to regenerate the bed 221 of adsorbent material in the adsorber 200. A regeneration gas stream can be supplied to the offline adsorber of the PPU 107 to regenerate the adsorbent material of the adsorber by heating the material, thereby releasing impurities adsorbed therein and outputting them from the adsorber via the regeneration gas.

[0082] The PPU 107 can be configured such that the fluid input to the first or second adsorber can be changed (e.g., via a valve position change, etc.) to switch the parallel adsorbers between an online state and an offline state (e.g., when the first adsorber is online, the second adsorber can be offline, and vice versa). The regeneration gas stream can be obtained via the waste stream output of the LP tower 111a or can be gas from another source in the industrial plant or the ASU system 1.

[0083] In some embodiments, there may be multiple first adsorbers that can operate in series, and there may also be multiple second adsorbers that can operate in series or in another manner to purify the compressed air. Figure 2 107b . For such embodiments, the plurality of first adsorbers may be arranged so that fluid passes through each first adsorber individually, or so that a separate portion of the fluid to be purified by the PPU 107 passes through each first adsorber when the plurality of first adsorbers are online. Similarly, the plurality of second adsorbers may be arranged so that fluid passes through each second adsorber individually, or so that a separate portion of the fluid to be purified by the PPU 107 passes through each second adsorber when the plurality of second adsorbers are online. Such an arrangement of the first and second adsorbers 107a and 107b can be used to allow the first adsorber 107a to be online while the second adsorber 107b is offline, and vice versa.

[0084] Each adsorber 200 of the PPU 107 (e.g., the first adsorber 107a, the second adsorber 107b, etc.) can include a bed of adsorbent material 221 retained within a container comprising one or more layers of adsorbent material. The first adsorbent layer of the first bed of adsorbent material 221 can be configured via composition, layer thickness, particle size, pore volume, density, and / or chemical structure (e.g., how the cations are attached to the zeolite framework) to selectively remove ambient moisture and also to remove CO2 and / or other impurities, and the second adsorbent layer of the first bed 221 can be configured via composition, layer thickness, particle size, pore volume, density, and / or chemical structure (e.g., how the cations are attached to the zeolite framework) to selectively remove carbon dioxide (CO2), nitrogen oxides (N2O), heavy hydrocarbons, and / or other fluid components from the compressed air delivered to the PPU 107 when the adsorber 200 is in an online state. In other embodiments, the adsorber vessel may have a single layer 231 that may include an adsorbent material or a combination of adsorbent materials to remove moisture, CO2, N2O, heavy hydrocarbons, and / or other fluid components from the compressed air delivered to the PPU 107 when the adsorber 200 is online.

[0085] It should be understood that when the adsorber 200 is in an offline state, it can undergo a regeneration process to regenerate one or more layers of adsorbent material within the adsorber. When returned to an online state, the adsorber can operate at a higher efficiency due to the regeneration of the one or more layers of material (e.g., adsorbent material) because the regeneration of the material can return the material to a state close to or in its original state for adsorbing the target material from the fluid stream.

[0086] For at least some embodiments, when the adsorber is in an online state, the regeneration gas flow can pass through the vessels 203 of the adsorber 200 along a flow path opposite to the flow path 210 of the fluid through the adsorber vessels. For such embodiments, when in an online state, the inlet 201 of the vessel can serve as the outlet for the regeneration gas, and when in an online state, the outlet 202 of the vessel can serve as the inlet for the regeneration gas.

[0087] The arrangement of the PPU 107 allows the compressed air output of one or more compressors of the compressor system 103 to be subsequently sent to the adsorber 200 of the PPU 107 via at least one conduit extending from the compressor system 103 or the pre-PPU cooler 104 (when used) for purification of the air via the one or more online adsorbers 200 of the PPU 107.

[0088] The compressed air is passed through the adsorption beds of each online adsorber of the PPU 107 to fully or partially remove undesirable components in the fluid stream, such as ambient moisture, CO2, N2O, hydrogen, carbon monoxide, heavy hydrocarbon components, etc. For example, as described above, the purified air can be output from the PPU 107 and sent to the main heat exchanger 109.

[0089] For the operation of PPU 107, CO2 can be used as a control component of the compressed air to monitor its purification. An analyzer or other type of sensor can be positioned to detect the CO2 content in the purified air output from PPU 107 to determine when the adsorbent material in the online adsorber is saturated, thereby triggering the online adsorber to switch offline, and also switching offline adsorbers online. In some embodiments, the analyzer can be positioned in communication with outlet 202 of adsorber 200, or can be placed in the conduit through which purified air passes from PPU 107 to heat exchanger 109.

[0090] In response to detecting that the CO2 content in the purified air output of PPU 107 reaches or exceeds a preselected threshold, switching between the online adsorber and the offline adsorber can be triggered. In other embodiments, the concentration of a different impurity or multiple different impurities in the purified air output of PPU 107 can be used to trigger the switching between the online adsorber and the offline adsorber of PPU 107.

[0091] like Figure 3 、 Figure 4 and Figure 5 As best shown, the container 203 of each adsorber 200 is structured so that the air to be purified can be moved along the Figure 3 、 Figure 4 and Figure 5A defined flow path 210 shown by the middle arrows passes through the container for passing through the different adsorbent material areas of the chamber of the container 203 to pass through the adsorbent material layer.

[0092] from Figures 3 and 4 As can be seen, the container of the radial adsorber 200 can include an inlet 201 and an outlet 202, the inlet receiving the compressed air purified by adsorption. The inlet 201 can be located on a side of the container, or at the inlet end of the container 203 at the head of the container 203. The outlet 202 can be located at one end of the container or on a side of the container. The adsorber 200 of the PPU 107 can have different configurations to define different flow paths 210 for air flowing between the inlet 201 and the outlet 202 within the container 203.

[0093] For example, Figure 3 As shown, the inlet 201 can be in fluid communication with the outer annular conduit structure 208 of the container, and the outlet 202 can be in fluid communication with the inner conduit structure 206. Figure 3 In the illustrated embodiment, when operating in an online state, the flow path 210 that may be defined within the vessel 203 of the adsorber 200 may include:

[0094] (i) air enters the container 203 from the inlet 201 along the first flow segment of the flow path 210,

[0095] (ii) the air then passes along a second flow segment of the flow path 210 through the first outer annular conduit 208, which defines the initial fluid feed path for the air,

[0096] (iii) the air then passes through the first layer of material 205 along a third flow segment of the flow path 210,

[0097] (iv) the air then passes along a fourth flow segment of flow path 210 through a second layer of material 207 downstream of the first layer 205 (e.g., above the first layer for a vertically oriented container, or downstream of the first layer for a horizontally oriented container),

[0098] (v) the air then flows from the second material layer 207 to the first inner conduit 206 along the fifth flow segment of the flow path 210, and

[0099] (vi) The air then flows from the first inner conduit 206 along the sixth flow segment of the flow path 210 to the outlet 202 for outputting the purified air from the container 203 after the air has passed through and contacted the first and second layers of material 205 and 207 .

[0100] First outer annular conduit 208 may have at least one inlet opening for receiving air from inlet 202 and at least one outlet opening adjacent to the outside of first layer of material 205 for delivering fluid from first outer annular conduit 208 to first layer of material 205 .

[0101] The first inner conduit 206 may be a conduit having an internal channel in fluid communication with one or more openings adjacent the inside of the second layer of material 207 for receiving air from that layer for outputting the air from the second layer of material 207 to the outlet 202 .

[0102] It should be understood that both the first inner conduit 206 and the first outer annular conduit 208 can be configured as conduit-type structures within the cavity or chamber of the container 203, each of which can define a passage for a fluid (e.g., air) to guide the fluid along a flow segment of the flow path 210 within the cavity or chamber of the container 203. For example, the first outer annular conduit 208 can be defined as an annular shape extending between the inlet 201 and the outside of the first layer 205 of the adsorbent material bed 221 to guide the fluid from the inlet 201 to the first layer 205. The inner conduit 206 can be an inner conduit positioned to guide air from the inside of the second layer 207 of the adsorbent material bed 221 to the outlet 202.

[0103] A first layer of material 205 may be placed within a first container of containers 203 and include a first material that is different from a second material of a second layer of material 207 that remains within a second container of containers 203. When the absorber is operating in an online state, the first layer of material 205 may be considered an upstream layer UL and the second layer of material 207 may be considered a downstream layer DL.

[0104] Each layer of material can be retained in a container having one or more holes to allow fluid to enter and exit the container. In some embodiments, the one or more holes can be defined by one or more screening elements of the container. Each container holding the material layer can include one or more screens, meshes, at least one plate having multiple holes, or at least one porous membrane of material having a specific preselected geometric shape to define at least a portion of the container. Each container can also be another type of container structure that can hold a layer of material in a desired position within the container 203 while also allowing air to enter and exit the layer to fluidly connect the first outer conduit 208 to the first inner conduit 206 so that air can pass along the flow path 210.

[0105] The materials of the first layer 205 and the second layer 207 can be different types of particulate materials (e.g., zeolite materials, catalytic materials, adsorbent materials, etc.). The first layer 205 can include alumina and / or silica or other materials for adsorbing at least water and CO2. The first layer can include a material primarily designed to adsorb water and CO2 to preferentially remove these impurities from the air. Alternatively, during normal operation of the ASU system 1, when the pre-PPU cooler 104 is operating in a non-tripped state (e.g., in its normal operating state), all or substantially all of the CO2 and water in the air within the first layer 205 of the adsorbent material bed 22 is removed.

[0106] The material of the second layer of material 207 can be a molecular sieve adsorbent material. The material of the second layer of material can include 13X, NaX, NaMSX, NaLSX, and / or other molecular sieve materials. The material of the second layer of material or adsorbent bed 221 can be used to adsorb heavy hydrocarbons (e.g., butane, acetylene, ethylene, propylene, etc.), NO, CO, and any remaining water and / or CO2 in the air after the air passes through the first layer of material 205 or other upstream portion of the adsorbent bed 221. The material of the second layer of material 207 can be used to preferentially remove CO2 and remaining water from the air to help ensure that such impurities are removed from the air, thereby resulting in the air output of the adsorber being free of water and CO2, or having very low water and CO2 levels below preselected CO2 threshold levels and preselected water threshold levels. Such levels can correspond to maintaining NO2 in the air at or below a first preselected threshold. In some embodiments, the N2O removed from the air delivered to the PPU 107 may reduce the N2O in the feed air by 50%-100%, 55%-100%, 55%-99%, or 50%-95% (e.g., when the pre-PPU cooler 104 is operating at its normal conditions (e.g., at a non-tripped condition), the air output from the PPU has at least 50% less N2O than the air delivered to the PPU). For example, the N2O content of the air delivered to the PPU may be less than 50% of the N2O content in the air output from the PPU when the pre-PPU cooler 104 is operating at its normal conditions, less than 5% of the N2O in the air output from the PPU when the pre-PPU cooler 104 is operating at its normal conditions, or less than 1% of the N2O in the air output from the PPU when the pre-PPU cooler 104 is operating at its normal conditions.

[0107] The adsorbent material bed 221 is sized and configured to remove less than 50% of the N2O in the air delivered to the PPU, or between 10% and 50% or 20% and 50% of the N2O in the air delivered to the PPU when the pre-PPU cooler 104 is in a tripped state and operating in the tripped state. The ASU system 1 may operate when the N2O level in the air output of the PPU is above its first preselected threshold value and the pre-PPU cooler 104 is tripped, as long as the N2O content remains below a second preselected threshold value associated with CO2 breakthrough into the ASU system 1 (e.g., the second preselected threshold value may be a value set such that 50% of the N2O in the air delivered to the PPU remains in the air output of the PPU, or more than 50% of the N2O in the air delivered to the PPU remains in the air output of the PPU, which value exceeds the second threshold value, which may correspond to an undesirable CO2 breakthrough condition).

[0108] For example, if the N2O content in the air delivered to the PPU is 0.4 ppm, when the chiller is operating in a tripped condition, the N2O content in the clean air output of the PPU may be in the range of 0.25 ppm to 0.2 ppm N2O, in the range of 0.25 ppm to 0.32 ppm N2O, in the range of 0.3 ppm to 0.25 ppm N2O, or in the range of 0.2 ppm to 0.32 ppm N2O. In such embodiments, when the chiller is operating normally, the N2O content in the air output of the PPU may be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.2 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0109] As another example, if the NO content in the air supplied to the PPU is 0.3 ppm, when the chiller is operating in a tripped condition, the NO content in the clean air output of the PPU may be in the range of 0.15 ppm to 0.2 ppm NO, in the range of 0.15 ppm to 0.24 ppm NO, in the range of 0.15 ppm to 0.3 ppm NO, or in the range of 0.27-0.15 ppm NO. In such embodiments, when the chiller is operating normally, the NO content in the air output of the PPU may be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.15 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0110] In some embodiments, the first layer of material 205 may include aluminum oxide or may include only aluminum oxide, while the second layer of material 207 may include 13X, NaX (e.g., NaMSX and / or NaLSX), NaMSX, or may include only NaLSX. In other embodiments, the first layer of material may include aluminum oxide and other materials, while the second layer of material 207 may include NaMSX and other materials. In still other embodiments, the first layer of material may include silicon dioxide, while the second layer of material may include NaMSX or other materials (e.g., NaX, NaLSX, 13X, etc.). In still other materials, there may be only a single layer of adsorption material 231. This single layer of material 231 may include NaMSX alone or in combination with one or more other materials (e.g., aluminum oxide, silica gel, NaLSX, NaX, CaX, 13X, etc.).

[0111] The dimensions of the bed of adsorbent material 221 may be within the chamber of the container 203. In some embodiments utilizing multiple layers, the dimensions may include a first dimension S1 of the first layer of adsorbent material 205 and a second dimension S2 of the second layer of adsorbent material. The dimensions of the bed 221 may be configured such that the first dimension S1 of the first layer of adsorbent material is between 20% and 90% of the total dimension of the bed 221, or between 30% and 75% of the total dimension of the bed 221, or between 30% and 65% of the total dimension of the bed 221, while the second dimension S2 of the second layer of adsorbent material 207 may be the remainder of the bed dimension (e.g., between 80% and 10% of the total dimension of the bed 221, or between 70% and 25% of the total dimension of the bed 221, or between 70% and 35% of the total dimension of the bed 221). In some embodiments, the first dimension S1 of the first layer of material may be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 66%, 67%, 70%, or 75% of the total dimension of the adsorbent material bed 221, while the second dimension S2 of the second layer of adsorbent material 207 may be 70%, 65%, 60%, 55%, 50%, 45%, 40%, 34%, 33%, 30%, or 25% of the total dimension of the bed 221. The material layer may include material having a particle size ranging from 1.0 mm to 5 mm. The bed and the layers of bed 221 may have the same width, length, or diameter. The thickness, length, or height of the bed may vary and may contribute to the overall size of the bed 221 and the different dimensions of the layers of material in the bed 221. In such embodiments, the dimensional difference between the first and second dimensions S1 and S2 may be due to different layer thicknesses, layer depths, layer lengths, or layer heights within the bed 221 of the vessel 203.

[0112] When adsorber 200 is offline and potentially undergoing regeneration, the flow path within vessel 203 can be reversed. Regeneration gas flow can enter vessel 203 via outlet 202, which serves as the regeneration gas flow inlet. The regeneration gas can then follow a reverse flow path through the vessel and exit vessel 203 via inlet 201, which serves as the regeneration gas flow outlet.

[0113] refer to Figure 4 The container of the adsorber 200 can include different internal configurations to define different flow paths 210 within the container 203. For example, the container 203 can include a first inner conduit 206 and a first outer annular conduit 208 that define a fluid flow path 210 within the container 203. It should be understood that both the first inner conduit 206 and the first outer annular conduit 208 can be configured as duct-type structures within the container cavity, each of which can define a passage for air to guide the air along a flow segment of the flow path 210 within the cavity or chamber of the container 203.

[0114] For example, the first inner conduit 206 may be a conduit having an internal channel that is in fluid communication with an opening adjacent to the inner side of the first layer of material 205, for conveying air received from the inlet 201 to the first layer of material 205 of the adsorbent material bed 221. The downstream end of the first inner conduit 206 may be closed to help drive fluid received from the inlet 201 near the first end of the vessel into the first layer of material 205. The first inner conduit 206 may be positioned within the vessel having one or more apertures so that the first layer of material 205 is in fluid communication with the first inner conduit 206 and can receive air from the first inner conduit 206.

[0115] The container of the first layer of material 205 can be positioned to enclose at least a portion of the first inner conduit 206. The first inner conduit 206 can have one or more openings therein that communicate with the interior of the first layer of material 205 so that air can flow out of the first inner conduit 206 and into the first layer of material 205. The one or more apertures of the container on its exterior that holds the first layer of material 205 and the one or more apertures on its interior can be perforations, tortuous channels defined in a screen of the container, or can be other types of apertures.

[0116] The first outer annular conduit 208 may have at least one inlet opening proximate the outside of the second layer of material 207 to receive air from the layer via one or more apertures in the container 203 that retain the second layer of material 207. The one or more apertures of the container that retain the second layer of material 207 on its outside and the one or more apertures on its inside may be perforations, tortuous channels defined in a screen of the container, or may be other types of apertures.

[0117] The first outer annular conduit 208 may further define a channel for directing or transporting air retained outside the second layer of material 207 within the second container of the container 203 to the outlet 202. The second container may have at least one aperture on its outer side and at least one aperture on its inner side to provide a fluid communication connection between the inner conduit 206 and the first outer annular conduit 208. The one or more apertures on the outer side and the one or more apertures on the inner side of the second container may be perforations, tortuous channels defined in the mesh of a screen, or other types of apertures.

[0118] The first and second containers holding the first and second layers of materials 205 and 207 may be defined by or include one or more screens, meshes, at least one plate having a plurality of holes, at least one material-perforated membrane, or other types of containment structures that can hold the layers of material in a desired position within container 301 while also allowing fluid to enter and exit the layers. In some embodiments (e.g., some vertical and horizontal adsorber embodiments), there may be no screens or other types of defined containers used to separate the layers.

[0119] It should be appreciated that when the container 203 is in its in-line state, the first layer of material 205 may be considered an upstream layer of material UL and the second layer of material 207 may be considered a downstream layer of material DL.

[0120] The vessel 203 may have a flow path 210 configured to pass fluid between the interior and exterior regions of the chamber of the vessel 203 to pass through the layers of material in the adsorbent material bed 221. It will be appreciated that the flow path 210 of the vessel 203 in an online state may include:

[0121] (i) the fluid flows from the inlet 201 into the container 203 along the first flow segment of the flow path 210,

[0122] (ii) subsequently, along a second flow segment of the flow path 210 through the first inner conduit 206, which defines an initial feed path for the air,

[0123] (iii) subsequently passing through the first layer of material 205 along a third flow segment of the flow path 210,

[0124] (iv) subsequently passing the second layer of material 207 along a fourth flow segment of the flow path 210;

[0125] (v) then enters the first outer annular conduit 208 for delivery along the fifth flow segment of the flow path 210 to the outlet 202;

[0126] (vi) It then follows a sixth flow segment along flow path 210 through outlet 202 to be output from container 203.

[0127] It will be appreciated that each layer of material within the bed of adsorbent material 221 may be retained in a container having one or more apertures to allow fluid to enter and exit the container. In some embodiments, the one or more apertures may be defined by one or more screening elements of the container. Each container holding a layer of material may include one or more screens, meshes, at least one plate having a plurality of apertures, or at least one porous membrane of material having a specific preselected geometry to define at least a portion of the container. Each container may also be another type of container structure that can hold a layer of material in a desired position within the container 203 while also allowing air to enter and exit the layer to fluidly connect the first outer annular conduit 208 to the first inner conduit 206 to allow air to pass along the flow path 210. In yet other embodiments, the layer of material may be configured as a single layer of material 231.

[0128] The materials of the first and second layers 205 and 207 can be different types of particulate materials (e.g., zeolite materials, catalytic materials, adsorbent materials, etc.). For some embodiments, the particle sizes of the materials can range from 1.0 to 5 mm. In some embodiments, the first layer material 205 can include or consist solely of alumina, while the second layer material 207 can include or consist solely of NaMSX. For example, the first layer material 205 can include alumina and / or silica, or other materials designed to adsorb at least water and CO2. The first layer material can include a material designed to primarily adsorb water and CO2, thereby preferentially removing these impurities from the air, thereby removing all or substantially all of the CO2 and water from the air within the first layer material 205 of the adsorbent material bed 221.

[0129] The material of the second layer of material 207 can be a molecular sieve adsorbent material. Such materials of the second layer of material can include 13X, NaX, NaMSX, NaLSX, and / or other molecular sieve materials. The material of the second layer of material can be used to adsorb heavy hydrocarbons (e.g., butane, ethylene, acetylene, propylene, etc.), N2O, CO, and any remaining water and / or CO2 in the air after the air passes through the first layer of material 205. The material of the second layer of material 207 can be used to preferentially remove CO2 and any remaining water from the air to help ensure that such impurities are removed from the air, so that the air output of the adsorber is free of water and CO2, or has very low water and CO2 levels below a preselected CO2 threshold level and a preselected water threshold level.

[0130] In some embodiments, the first layer material 205 may include aluminum oxide or may include only aluminum oxide, while the second layer material 207 may include NaLSX or may include only NaLSX. In other embodiments, the first layer material may include aluminum oxide and other materials, while the second layer material 207 may include NaLSX and other materials. In still other embodiments, the first layer material may include silicon dioxide, while the second layer material may include NaMSX or other materials (e.g., NaLSX, NaX, 13X, CaX, etc.).

[0131] The dimensions of the bed of adsorbent material 221 may be within the chamber of the container 203. The dimensions may include a first dimension S1 of the first layer of adsorbent material 205 and a second dimension S2 of the second layer of adsorbent material (e.g., the total dimension of the bed 221 may be the sum of the first dimension S1 and the second dimension S2, or may include the sum of the first dimension S1 and the second dimension S2 in addition to the dimensions of one or more third layers).

[0132] The dimensions of the bed 221 can be configured such that the first dimension S1 of the first layer of adsorbent material is between 20% and 90% of the total dimension of the bed 221, or between 30% and 75% of the total dimension of the bed 221, while the second dimension S2 of the second layer of adsorbent material 207 can be the remainder of the bed dimension (e.g., between 80% and 10% of the total dimension of the bed 221, or between 70% and 25% of the total dimension of the bed 221). In some embodiments, the first dimension S1 of the first layer of material can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 66%, 67%, 70%, or 75% of the total dimension of the bed 221, while the second dimension S2 of the second layer of adsorbent material 207 can be 70%, 65%, 60%, 55%, 50%, 45%, 40%, 34%, 33%, 30%, or 25% of the total dimension of the bed 221. The bed and the layers of bed 221 may have the same width or diameter. The thickness, length, or height of the bed may vary and may contribute to the overall size of bed 221 and the different sizes of the layers of material in bed 221. In such embodiments, the dimensional difference between the first and second dimensions S1 and S2 may be caused by different layer thicknesses, layer lengths, layer depths, or layer heights within bed 221 of vessel 203.

[0133] When adsorber 200 is offline and potentially undergoing regeneration, the flow path within vessel 203 can be reversed. Regeneration gas flow can enter vessel 203 via outlet 202, which serves as the regeneration gas flow inlet. The regeneration gas can then follow a reverse flow path through the vessel and exit vessel 203 via inlet 201, which serves as the regeneration gas flow outlet.

[0134] The material of the second layer 207 or adsorbent material bed 221 of adsorber 200 can be used to adsorb heavy hydrocarbons (e.g., butane, ethylene, acetylene, propylene, etc.), N2O, CO, and any remaining water and / or CO2 in the air after the air passes through the first layer 205 or other upstream portion of the adsorbent material bed 221. The material of the second layer 207 can be used to preferentially remove CO2 and remaining water from the air to help ensure that such impurities are removed from the air, such that the air output of the adsorber is free of water and CO2, or has very low water and CO2 levels below a preselected CO2 threshold level and a preselected water threshold level. Such levels can correspond to maintaining N2O in the air at or below a first preselected threshold level. In some embodiments, when pre-PPU cooler 104 is operating under its normal conditions (e.g., under a non-tripped condition), the N2O removed from the air by the PPU 107 can be between 20% and 100%, 25% and 100%, 25% and 99%, or 20% and 95% of the N2O in the air delivered to the PPU. For example, when the pre-PPU cooler 104 is operating in its normal state, the N2O content in the air delivered to the PPU may be less than 25% of the N2O content in the air output of the PPU, when the pre-PPU cooler 104 is operating under its normal conditions, the N2O content in the air delivered to the PPU is less than 5% of the N2O in the air output of the PPU, or when the pre-PPU cooler 104 is operating under its normal conditions, the N2O content in the air delivered to the PPU is less than 1% of the N2O in the air output of the PPU.

[0135] In contrast, the adsorbent material bed 221 may be sized and configured such that when the pre-PPU cooler 104 is in a tripped state and operating in the tripped state, the N2O removed from the air output of the PPU 107 may be less than 50% of the N2O in the air delivered to the PPU, or may be between 10% and 50% or 20% and 50% of the N2O in the air delivered to the PPU. The ASU system 1 may operate when the N2O level in the PPU air output is above its first preselected threshold while the pre-PPU cooler 104 is tripped, as long as the N2O content remains below a second preselected threshold associated with CO2 breakthrough into the ASU system 1 (e.g., the second preselected threshold corresponds to 50% N2O remaining in the air output of the PPU delivered to the PPU, or more than 50% N2O remaining in the air output of the PPU delivered to the PPU exceeds the second threshold, which may correspond to an undesirable CO2 breakthrough condition).

[0136] For example, if the N2O content in the air delivered to the PPU is 0.4 ppm, when the chiller is operating in a tripped condition, the N2O content in the clean air output of the PPU may be in the range of 0.25 ppm to 0.2 ppm N2O, in the range of 0.25 ppm to 0.32 ppm N2O, in the range of 0.3 ppm to 0.25 ppm N2O, or in the range of 0.2 ppm to 0.32 ppm N2O. In such embodiments, when the chiller is operating normally, the N2O content in the air output of the PPU may be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.2 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0137] As another example, if the NO content in the air delivered to the PPU is 0.3 ppm, when the chiller is operating in a tripped condition, the NO content in the clean air output of the PPU may be in the range of 0.15 ppm to 0.0675 ppm NO, in the range of 0.15 ppm to 0.24 ppm NO, in the range of 0.15 ppm to 0.3 ppm NO, or in the range of 0.27-0.15 ppm NO. In such embodiments, when the chiller is operating normally, the NO content in the air output of the PPU may be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.15 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0138] refer to Figure 5 The vessels of the adsorber 200 can include different internal configurations to define different flow paths 210 within the vessel 203. For example, the vessel 203 can include a bed of adsorbent material 221 comprising a first layer of material 205 and a second layer of material 207. A first vessel holding the first layer of material 205 and a second vessel holding the second layer of material 207 can be placed within the chamber of the vessel 203. Each vessel can include one or more apertures on its downstream and upstream sides so that the vessels are in fluid communication with each other and the inlet 201 of the vessel is in fluid communication with the outlet 202. The one or more apertures on each side of each vessel holding the corresponding material layer can be one or more perforations, a tortuous channel defined in the mesh of a screen, or one or more other types of apertures. The material layers can be arranged to cause air to flow along the flow path 210, such that air enters the vessel 203 via the inlet 201, then passes through the first layer of material 205, then passes through the second layer of material 207, and then, when the adsorber 200 is in an online state, exits the vessel 203 via the outlet 202.

[0139] The materials of the first and second layers 205 and 207 can be various types of particulate materials (e.g., zeolite materials, catalytic materials, adsorbent materials, etc.). In some embodiments, the size of the particulate materials can range from 1.0 mm to 5.0 mm. The first layer of material 205 can include alumina and / or silica, or other materials designed to adsorb at least water and CO2. The first layer of material can include a material designed to primarily adsorb water and CO2, thereby preferentially removing these impurities from the air, thereby removing all or substantially all of the CO2 and water from the air within the first layer of material 205 of the adsorbent material bed 221.

[0140] The material of the second layer of material 207 can be a molecular sieve adsorbent material. Such materials for the second layer of material can include 13X, NaX, NaMSX, NaLSX, and / or other molecular sieve materials. The material of the second layer of material 207 can be used to adsorb heavy hydrocarbons (e.g., ethylene, butane, acetylene, propylene, etc.), N2O, CO, and any remaining water and / or CO2 in the air after the air passes through the first layer of material 205. The material of the second layer of material 207 can be used to preferentially remove CO2 and water from the air to help ensure that such impurities are removed from the air, so that the air output of the adsorber is free of water and CO2, or has very low water and CO2 levels below a preselected CO2 threshold level and a preselected water threshold level.

[0141] In some embodiments, the first layer of material 205 may include aluminum oxide or may include only aluminum oxide, while the second layer of material 207 may include NaLSX or may include only NaLSX. In other embodiments, the first layer of material may include aluminum oxide and other materials, while the second layer of material 207 may include NaLSX and other materials. In still other embodiments, the first layer of material may include silicon dioxide, while the second layer of material may include NaX, NaMSX, 13X, or other materials.

[0142] The dimensions of the bed of adsorbent material 221 may be within the chamber of the container 203. The dimensions may include a first dimension S1 of the first layer of adsorbent material 205 and a second dimension S2 of the second layer of adsorbent material (e.g., the total dimension of the bed 221 may be the sum of the first dimension S1 and the second dimension S2, or may include the sum of the first dimension S1 and the second dimension S2 in addition to the dimensions of one or more third layers).

[0143] The dimensions of the bed 221 can be configured such that the first dimension S1 of the first layer of adsorbent material is between 20% and 90% of the total dimension of the bed 221, or between 50% and 75% of the total dimension of the bed 221, or between 30% and 65% of the total dimension of the bed 221, while the second dimension S2 of the second layer of adsorbent material 207 can be the remainder of the bed dimension (e.g., between 10% and 80% of the total dimension of the bed 221, between 50% and 25% of the total dimension of the bed 221, or between 35% and 70% of the total dimension of the bed 221). In some embodiments, the first dimension S1 of the first layer of material may be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 66%, 67%, 70%, or 75% of the total dimension of the bed 221 of adsorbent material, while the second dimension S2 of the second layer of adsorbent material 207 may be 70%, 65%, 60%, 55%, 50%, 45%, 40%, 34%, 33%, 30%, or 25% of the total dimension of the bed 221. The bed and the layers of bed 221 may have the same width or diameter. The thickness or height of the bed may vary and may contribute to the overall size of the bed 221 and the different dimensions of the layers of material in the bed 221. In such embodiments, the dimensional difference between the first and second dimensions S1 and S2 may be due to different layer thicknesses, layer depths, or layer heights within the bed 221 of the vessel 203.

[0144] When adsorber 200 is offline and potentially undergoing regeneration, the flow path within vessel 203 can be reversed. Regeneration gas flow can enter vessel 203 via outlet 202, which serves as the regeneration gas flow inlet. The regeneration gas can then flow through the vessel in the reverse direction by passing through second layer material 207 and then through first layer material 205. The regeneration gas then exits vessel 203 via inlet 201, which serves as the regeneration gas flow outlet.

[0145] It will be appreciated that the material of the second layer of material 207 or the adsorbent material bed 221 of the adsorber 200 can be used to adsorb heavy hydrocarbons (e.g., ethylene, butane, acetylene, propylene, etc.), N2O, CO, and any remaining water and / or CO2 in the air after the air has passed through the first layer of material 205 or other upstream portion of the adsorbent material bed 221. The material of the second layer of material 207 can be used to preferentially remove CO2 and remaining water from the air to help ensure that such impurities are removed from the air, such that the air output of the adsorber is free of water and CO2, or has very low water and CO2 levels below a preselected CO2 threshold level and a preselected water threshold level. Such levels can correspond to maintaining N2O in the air at or below a first preselected threshold level. In some embodiments, when the pre-PPU cooler 104 is operating under its normal conditions (e.g., under a non-tripped condition), the N2O in the air output from the PPU 107 can be reduced by 20%-100%, 25%-100%, 25%-99%, or 20%-95% compared to the N2O in the air delivered to the PPU. For example, the N2O content in the air delivered to the PPU can be less than 25% of the N2O content in the PPU air output when the pre-PPU cooler 104 is operating under its normal conditions, less than 5% of the N2O in the PPU air output when the pre-PPU cooler 104 is operating under its normal conditions, or less than 1% of the N2O in the air delivered to the PPU when the pre-PPU cooler 104 is operating under its normal conditions.

[0146] In contrast, the adsorbent material bed 221 may be sized and configured such that when the pre-PPU cooler 104 is in the tripped state and operating in the tripped state, the amount of N2O removed from the air output of the PPU 107 may be less than 50% of the N2O in the air delivered to the PPU, may be between 20% and 50% of the N2O in the air delivered to the PPU, or may be between 10% and 50% of the N2O in the air delivered to the PPU. The ASU system 1 may operate when the pre-PPU cooler 104 is tripped when the N2O level in the PPU air output is above its first preselected threshold value as long as the N2O content remains below a second preselected threshold value associated with CO2 breakthrough into the ASU system 1 (e.g., 50% of the N2O in the air delivered to the PPU remains in the air output of the PPU, or more than 50% of the N2O in the air delivered to the PPU remains in the air output of the PPU, which may correspond to an undesirable CO2 breakthrough condition).

[0147] For example, if the N2O content in the air delivered to the PPU is 0.4 ppm, when the chiller is operating in a tripped condition, the N2O content in the clean air output of the PPU may be in the range of 0.25 ppm to 0.2 ppm N2O, in the range of 0.25 ppm to 0.32 ppm N2O, in the range of 0.3 ppm to 0.25 ppm N2O, or in the range of 0.2 ppm to 0.32 ppm N2O. In such embodiments, when the chiller is operating normally, the N2O content in the air output of the PPU may be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.2 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0148] As another example, if the NO content in the air delivered to the PPU is 0.3 ppm, when the chiller is operating in a tripped condition, the NO content in the clean air output of the PPU may be in the range of 0.15 ppm to 0.0675 ppm NO, in the range of 0.15 ppm to 0.24 ppm NO, in the range of 0.15 ppm to 0.3 ppm NO, or in the range of 0.27-0.15 ppm NO. In such embodiments, when the chiller is operating normally, the NO content in the air output of the PPU may be in the range of 0 ppm to 0.015 ppm, 0 ppm to 0.15 ppm, less than 0.015 ppm, or 0.03 ppm to 0.015 ppm.

[0149] In embodiments of adsorber 200, including those discussed herein and illustrated in the figures, the first material of first layer material 205 can be a silica gel and / or alumina granular material that is used to remove water from a fluid (e.g., via the composition and pore structure of the granular material to facilitate the removal of water from the fluid via adsorption), and the second material of second layer material 207 can be a molecular sieve material. For example, the material of second layer material 207 can be a high-capacity adsorption material, such as a NaLSX zeolite material, and thus the size of second layer material 207 can be the same as that of first layer material 205, or smaller than that of first layer material 205.

[0150] We have determined that making the first layer of material 205 a larger layer can allow for 100% water removal via the first layer of material 205, and for the second layer of material 207 to be sized sufficiently for 100% CO2 removal, while allowing some N2O breakthrough above a normally allowed threshold level for a preselected N2O breakthrough period in the event that the pre-PPU cooler 104 is unable to effectively cool the air to the desired temperature range (e.g., due to a malfunction or process issue). Allowing N2O breakthrough during operation while the pre-PPU cooler 104 is undergoing maintenance or is otherwise in a tripped state can allow the ASU system 1 to operate using less expensive, smaller-sized adsorbers 200 in the PPU 107, which can reduce operating and capital costs.

[0151] For example, the adsorbent material bed 221 of the adsorber 200 of the PPU 107 can be configured to adsorb N2O and any remaining water and / or CO2 from the air after the air passes through the first layer of material 205 or an upstream portion of the adsorbent material bed 221. The adsorbent material bed 221 can be sized and configured to include materials that preferentially remove CO2 and water from the air to help ensure that such impurities are removed from the air, thereby ensuring that the air output from the PPU 107 is free of water and CO2, or has very low levels of water and CO2, below a preselected CO2 threshold level and a preselected water threshold level. Such levels can correspond to maintaining N2O in the air at or below a first preselected threshold level. In some embodiments, the N2O removed from the air output of the PPU 107 can be 20%-100%, 25%-100%, 25%-99%, or between 20%-95% of the N2O in the air delivered to the PPU when the pre-PPU cooler 104 is operating under normal conditions (e.g., under non-trip conditions). For example, when the pre-PPU cooler 104 is operating in its normal state, the N2O content in the air delivered to the PPU may be less than 25% of the N2O content in the PPU air output, when the pre-PPU cooler 104 is operating under its normal conditions, the N2O content in the air delivered to the PPU is less than 5% of the N2O in the PPU air output, or when the pre-PPU cooler 104 is operating under its normal conditions, the N2O content in the air delivered to the PPU is less than 1% of the N2O in the PPU air output.

[0152] In contrast, the adsorbent material bed 221 may be sized and configured such that when the pre-PPU cooler 104 is in the tripped state and operating in the tripped state, less than 50% of the N2O in the air delivered to the PPU is removed from the air output of the PPU 107, between 20% and 50% of the N2O in the air delivered to the PPU, or between 10% and 50% of the N2O in the air delivered to the PPU. The ASU system 1 may operate when the N2O level in the PPU air output is above its first preselected threshold while the pre-PPU cooler 104 is tripped (e.g., 50% or more of the N2O in the air delivered to the PPU remains in the PPU air output, which may correspond to an undesirable CO2 breakthrough condition), as long as the N2O content remains below a second preselected threshold associated with CO2 breakthrough into the ASU system 1.

[0153] We have determined that it is safe to allow elevated levels of N2O to pass through PPU 107 for preselected periods of time. For example, we have determined that allowing elevated levels of N2O to pass through PPU 107 does not pose immediate safety or other immediate operational issues. In contrast, CO2 breakthrough would pose such issues. By allowing the ASU system to operate at full capacity during maintenance or other trips of pre-PPU cooler 104, the ASU can continue to operate at a higher overall profit and efficiency than if the ASU were shut down or operated at a lower capacity to account for the operating status of the pre-PPU cooler.

[0154] Because elevated N2O levels do not pose an immediate problem, we determined that operational tradeoffs allow N2O to breach PPU 107 while maintaining tight CO2 control. Furthermore, elevated N2O conditions can be further mitigated during other operating times of ASU system 1 that are more beneficial to the plant operator without significantly offsetting the operational efficiencies and cost savings achieved by allowing the system to operate with limited N2O breakthrough. For example, when the system is not operating with elevated N2O levels, ASU system 1 can take corrective actions to help mitigate N2O buildup that is adversely affecting the plant's operating units. For example, the defrost interval of ASU system 1 can be adjusted to account for the duration of the impact of elevated N2O on system 1 operations. Such defrost intervals typically occur every 5-8 years, 3-10 years, 4-10 years, or 3-8 years. Slight adjustments to the interval (e.g., 0.5-4 months, 0.5-1 month, shortening the duration by up to a few months, etc.) may have a negligible impact on the cost and efficiency improvements provided by operating the ASU system 1 at high N2O levels, which is the cause of the periodic operating problems of the pre-PPU cooler 104.

[0155] In embodiments of adsorber 200, first layer material 205 may also include particles having an average particle size different from the average particle size of second layer material 207. In other embodiments, it is contemplated that the first and second layer materials may have the same average particle size or similar average particle sizes.

[0156] Embodiments of the ASU system 1 may utilize a controller to monitor and control the operation of the system. For example, Figures 1 to 5 The illustrated embodiment of the ASU system, as well as other embodiments explicitly discussed herein, may include a controller such as Figure 6 An exemplary controller is shown. It may include temperature sensors, pressure sensors, flow sensors, and concentration sensors for detecting the concentration of one or more compounds (e.g., O2, Ar, CO2, N2, Xe, Kr, CO, water, etc.) and for sensing and / or detecting the flow rate, concentration, temperature, or pressure of fluids flowing through various components or units of the apparatus and / or conduits between those units. For example, sensors may be provided for detecting (i) the flow rate, pressure, temperature, and feed concentration of air delivered to compressor system 103, (ii) the flow rate, pressure, temperature, and / or feed concentration of air output from compressor system 103 delivered to PPU 107, (iii) the flow rate, pressure, temperature, and / or feed concentration of air output from PPU 107 delivered to heat exchanger 109, and / or (iv) the flow rate, pressure, temperature, and component concentration of fluids entering and exiting multi-tower assembly 111. Other sensors may also be placed in ASU system 1 to monitor and control the operation of these components of the system. A controller may be provided to receive data from these sensors and adjust the operation of different components based on the received sensor data. Examples of such controllers are Figure 6 As shown, the ASU system 1 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 execute at least one automatic control program stored in the computer-readable medium (e.g., non-transitory memory, flash memory, etc.), which defines a method for controlling the operation of the ASU system 1 and / or one or more components of the system.

[0157] It should be understood that embodiments of the controller can also be used to utilize other sensor data to actuate different plant operations and use different conduits to implement different fluid flow paths to and from different components. In some embodiments, the controller can be connected to a display and at least one input device and / or input / output device to facilitate outputting data to and receiving input from a user or operator. For example, the controller can be connected to an operator workstation or a plant operator's computer. The controller can also be connected to other plant control components to facilitate integration into a larger plant automated process control system.

[0158] from Figure 7As can be seen, an exemplary method for purifying air via a PPU 107 of an ASU system 1 is provided, wherein the system 1 has a pre-PPU cooler 104 upstream of the PPU 107 to cool the compressed air output of the compressor system 103 before it is fed into the PPU 107. For example, the method may include passing air through at least one adsorber 200 of the PPU 107 to pass the air through a bed of adsorbent material 221 within a vessel 203 of the adsorber 200. In response to a determination that the pre-PPU cooler 104 has a problem that causes the pre-PPU cooler 104 to trip or require the pre-PPU cooler 104 to be taken offline, the ASU system may continue to operate at full capacity even if the N2O in the air output of the PPU 107 exceeds a first preselected threshold value, while the N2O in the air output of the PPU 107 is below a second preselected threshold value associated with a CO2 breakthrough condition. The ASU system 1 may be configured to operate the ASU system 1 at full capacity even if the N2O in the air output of the PPU 107 exceeds a first preselected threshold, without operating a redundant pre-PPU cooler to cool the compressed air of the compressor system 103 before sending the compressed air to the PPU 107 to replace the pre-PPU cooler 104 (which is determined to have a problem that causes the pre-PPU cooler 104 to trip or require the pre-PPU cooler 104 to be taken offline).

[0159] The method may also include taking remedial action to address the excess N2O in the air output by the PPU 107 after the pre-PPU cooler 104 of the ASU system 1 is back online and the air output by the PPU 107 no longer has N2O exceeding the first preselected threshold. Remedial action need not be taken immediately after the pre-PPU cooler 104 is back online and operating under normal conditions (e.g., non-tripped conditions). For example, the remedial action taken may be scheduled after the pre-PPU cooler 104 is brought back online at a time that is more convenient for the operator of the ASU system. The remedial action subsequently taken may take into account the time that the pre-PPU cooler 104 was not operating adequately to cool the compressed air to a more ideal temperature, which may have reduced the ability of the adsorbent material of the adsorbent bed 221 to remove N2O from the air passing through the adsorber 200 while the ASU was operating while the pre-PPU cooler 104 was in a tripped state. The remedial action that may be taken will shorten the cycle time of the thermal swing adsorption (TSA). Another remedial action that may be taken includes adjusting the ASU system's defrost interval to account for the duration of time the ASU system 1 has been operating with N2O in the air output of the PPU 107 exceeding a first preselected threshold. Adjusting the defrost interval may include reducing the amount of time until defrost of the ASU system 1 is scheduled to occur or will occur. For example, adjusting the defrost interval may be informed by ASU system operating data indicating a higher accumulation rate than the design basis, provided that the industry maximum limit for a correspondingly sized ASU system is not exceeded. In some embodiments, such adjustments may be facilitated via online calculations (taking into account system parameters, etc.) and displayed on a screen to alert operators to how much time they have remaining to perform the defrost operation.

[0160] As another example, adjustments to the defrost time interval can be indicated by detecting N2O and / or CO2 accumulation in the ASU system so that the defrost schedule for the ASU system 1 can be triggered at shorter intervals due to the ASU system operating at high N2O levels for a relatively short period of time during a chiller trip. Such adjustments naturally occur when the ASU system 1 operates at high N2O levels during pre-PPU chiller trip operating conditions.

[0161] As discussed herein, embodiments of the method can utilize a PPU having one or more adsorbers 200. For example, the adsorbent material bed 221 can include a first layer of adsorbent material 205 and a second layer of adsorbent material 207. The first layer of adsorbent material can include a material that removes water and / or CO2 from air (e.g., an aluminum oxide material, etc.). The second layer of adsorbent material 207 can be located downstream of the first layer of adsorbent material 205 to contact the air after the air passes through the first layer of adsorbent material 205. The second material of the second layer of adsorbent material can include, for example, NaLSX or NaMSX material. The first layer of adsorbent material 205 can have a first size S1, and the second layer of adsorbent material 207 can have a second size S2. As described above, the first size S1 can be equal to or greater than the second size S2.

[0162] Embodiments of the method may also include other steps. For example, the method may also include monitoring the CO2 content in the air output of the PPU 107. This monitoring may be performed to help ensure that CO2 does not break through the PPU 107 and exceed a preselected CO2 threshold level. An analyzer may be used to perform this monitoring. For example, the analyzer may be a sensor connected to the ASU system controller to facilitate such monitoring.

[0163] Embodiments of the method may also include other steps. For example, the method may also include maintaining a spare parts inventory to service pre-PPU coolers on-site to minimize cooler maintenance time. Such stockpiled spare parts may include parts for the most common mechanical failures, enabling faster resolution of the most common cooler operational issues. This helps minimize the time the ASU system may be operating when a cooler is in a tripped state.

[0164] We have determined that embodiments of our ASU system 1, PPU 107, adsorber 200, and methods of using them can provide significant advantages, such as reduced capital costs, easier operation and maintenance, overall lower electricity costs through the use of chillers, and increased operational flexibility. For example, embodiments of adsorber 200 can utilize smaller molecular sieve layers of adsorbent material to remove NO, which can significantly reduce the size of adsorber 200 required for PPU 107. This can improve operating efficiency and reduce the overall capital, maintenance, and operating costs of a PPU using such adsorber 200. Embodiments of our PPU 107 using embodiments of our adsorber 200 can also eliminate the need for chiller redundancy in the pre-PPU chiller 104 of the ASU system 1. In the event that an online pre-PPU chiller 104 experiences a problem or requires maintenance, eliminating the need for a backup pre-PPU chiller 104 to be online can significantly reduce the capital cost of the system 1 and reduce the floor space required for such a system. In some types of facilities, this can save approximately $250,000 in capital costs by eliminating the need for additional chillers and their installation.

[0165] Embodiments of the PPU 107 and adsorber 200 may also allow the ASU system 1 to operate without a specialized NO removal layer, which typically requires a higher temperature regeneration gas than would be required using other adsorbent materials with lower adsorbent material regeneration temperatures. For example, embodiments of the adsorber 200 may avoid the use of a layer of CaX adsorbent material, which may require the use of a regeneration gas temperature of 300° C. or higher. Consequently, embodiments may provide lower operating costs by requiring a lower temperature regeneration gas stream.

[0166] Embodiments of the PPU 107 and adsorber 200 allow the ASU system 1 to operate at full capacity during a pre-PPU cooler 104 failure or trip. This also avoids the need to use the redundant pre-PPU cooler 104 to cool the compressed air being fed to the PPU 107. This operational flexibility allows for reduced capital, operating, and maintenance costs, while providing improved output for the ASU system 1. The ASU system can also be configured to monitor for excess N2O and CO2 accumulation, further enhancing the safety of ASU system operation and facilitating safe adjustment of defrost intervals, as operating an ASU with high N2O levels may require shortening defrost intervals. For example, an N2O analyzer and / or a CO2 analyzer can be positioned to monitor N2O and CO2 accumulation within the multi-tower assembly 111 to help ensure that the ASU system 1 defrost interval is appropriately adjusted to account for periods of time when the pre-PPU cooler 104 is in a tripped state and the ASU system 1 is experiencing high N2O concentration levels. Thus, the overall profitability of an operator of an ASU system can be greatly improved by utilizing an embodiment of an ASU system 1 that utilizes a PPU 107 having an embodiment of our adsorber 200, while also allowing the ASU system 1 to operate in a safe manner.

[0167] It should be understood that the embodiments explicitly shown and discussed herein can be modified to meet a particular set of design objectives or a particular set of design criteria. For example, the arrangement of valves, pipes, and other conduit elements (e.g., conduit connections, piping, seals, etc.) used to interconnect different units of a plant to achieve fluid communication for fluid flow between the different units can be arranged to meet a particular plant layout design, taking into account the available area of ​​the plant, the equipment of the plant's established size, and other design considerations. As another example, the flow rate, pressure, and temperature of the fluid through the radial adsorbers and through other plant elements can be varied to account for different plant design configurations and other design criteria. As another example, the number of radial adsorbers in the PPU 107 and their arrangement can be adjusted to meet a particular set of design criteria. As another example, the material composition of the adsorbers 200, the PPU 107, and the various structural components of the ASU system 1 can be any type of suitable material that may be required to meet a particular set of design criteria. The embodiments can be used in conjunction with any type of adsorber vessel (radial, vertical, horizontal, vertical cross flow, etc.) for the PPU 107. The pre-PPU cooler 104 can be any type of cooler—mechanical, absorption, etc. Embodiments can be configured to utilize any number of ASU trains, coolers (in parallel or series), TSA vessels, etc. While the preferred embodiment is a TSA implementation, other adsorption cycles are equally applicable where a cooler can benefit the process, such as pressure swing, vacuum swing, etc. This also applies if other unit operations exist between the pre-PPU cooler 104 and the PPU 107.

[0168] It should be understood that embodiments of the ASU system 1 can be configured as an air separation plant, or incorporated into another type of plant, in which at least one adsorber 200 can be used. The adsorption system, PPU 107, and adsorber 200 can each 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-transitory memory, and at least one transceiver for communicating with the sensor elements, valves, and controllers, the transceiver being used to provide a user interface for the automated process control system, which may be running on a workstation and / or another computer device in the plant).

[0169] As another example, it is contemplated that certain features described separately or as part of an embodiment can be combined with other separately described features or parts of other embodiments. Thus, the elements and acts of the various embodiments described herein can be combined to provide further embodiments. Thus, while certain exemplary embodiments of adsorbers, adsorption systems, PPUs, plants having adsorption systems utilizing one or more adsorbers, ASU systems, and methods of making and using the same have been shown and described above, it should be clearly understood that the present invention is not limited thereto, but may be embodied and implemented in other ways within the scope of the following invention claims.

Claims

1. An adsorber for a pre-purification unit (PPU) of an air separation unit (ASU) system, comprising: a container connected between the compressor system and the heat exchanger; a bed of adsorption material disposed in the container; The bed of adsorbent material is configured to remove water and carbon dioxide (CO2) from a compressed air stream fed to the PPU, and is further configured to remove nitrous oxide (N2O) so that N2O in an air output from the PPU is below a first preselected threshold; The bed of adsorbent material is configured such that, in response to a pre-PPU cooler being determined to have a problem that causes the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline, the PPU can operate at full capacity such that the N2O in the air output of the PPU exceeds the first preselected threshold and is below a second preselected threshold associated with CO2 breakthrough.

2. The adsorber according to claim 1, wherein the bed of adsorbent material comprises a first layer of adsorbent material and a second layer of adsorbent material, the first layer of adsorbent material comprising alumina, and the second layer of adsorbent material comprising NaX, NaLSX or NaMSX.

3. The adsorber of claim 1, wherein the bed of adsorbent material comprises a single layer of material or multiple layers of material.

4. The adsorber of claim 3, wherein the first preselected threshold is in the range of 0-0.2 ppm N2O, and the second preselected threshold is in the range of 0.2-0.32 ppm N2O.

5. The adsorber of claim 1 , wherein the first preselected threshold is selected so that 20%-100% of the N2O in the air sent to the PPU is removed from the air, and the second preselected threshold is selected so that less than 50% of the N2O in the air sent to the PPU is removed from the air.

6. A method for purifying air via a pre-purification unit (PPU) of an air separation unit (ASU) system, the ASU system having a pre-PPU cooler located upstream of the PPU for cooling the compressed air before it is sent to the PPU, the method comprising the following steps: passing air through an adsorber of the PPU so that the air passes through a bed of adsorbent material within a container of the adsorber; In response to a determination that a problem exists with the pre-PPU cooler that causes the pre-PPU cooler to trip or requires the pre-PPU cooler to be taken offline, continuing to operate the ASU system at full capacity even though nitrous oxide (N2O) in the air output of the PPU exceeds a first preselected threshold and is below a second preselected threshold associated with carbon dioxide (CO2) breakthrough.

7. The method of claim 6, wherein the adsorption material bed comprises alumina, silica gel, 13X, NaX, NaLSX, NaMSX, or a combination thereof, and has a particle size ranging from 1.0 mm to 5 mm.

8. The method according to claim 6, comprising the steps of: The carbon dioxide CO2 content in the air output of the PPU is monitored.

9. The method according to claim 6, comprising the steps of: After the pre-PPU cooler of the ASU system is back online and the air output of the PPU no longer has N2O exceeding the first preselected threshold, remedial action is taken to address excess N2O in the air output of the PPU.

10. The method of claim 9, wherein the remedial action comprises shortening a defrost interval of the ASU system to account for a duration of operation of the ASU system with N2O in the air output of the PPU exceeding the first preselected threshold.

11. The method of claim 10, wherein shortening the defrost interval comprises reducing an amount of time before the ASU system is scheduled to defrost.

12. The method according to claim 6, wherein: The first preselected threshold is in the range of 0-0.2 ppm N2O, and the second preselected threshold is in the range of 0.2-0.32 ppm N2O, or The first preselected threshold is selected to remove 20%-100% of the N2O from the air delivered to the PPU, and the second preselected threshold is selected to remove less than 50% of the N2O from the air delivered to the PPU.

13. The method of claim 6 , wherein the ASU system is allowed to continue operating at full capacity for a preselected duration not exceeding 14 days even if the N 2 O in the air output of the PPU exceeds the first preselected threshold and is below the second preselected threshold associated with CO 2 breakthrough.

14. The method of claim 6, wherein even if the N2O in the air output of the PPU exceeds the first preselected threshold and is below the second preselected threshold associated with CO2 breakthrough, continuing to operate the ASU system at full capacity is permitted for a preselected duration not exceeding 7 days.

15. The method of claim 6, wherein even if the N2O in the air output of the PPU exceeds the first preselected threshold and is below the second preselected threshold associated with CO2 breakthrough, continuing to operate the ASU system at full capacity is permitted for a preselected duration not exceeding 2 days.

16. The method of claim 6 , wherein the ASU system continues to operate at full capacity without a redundant pre-PPU cooler operating even if NO in the air output of the PPU exceeds the first preselected threshold to cool the compressed air before sending the compressed air to the PPU to replace the pre-PPU cooler determined to have the problem that caused the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline.

17. An air separation unit (ASU) system comprising: a pre-purification unit (PPU) connected to a compressor system to receive compressed air from the compressor system, the PPU being connected to a heat exchanger to deliver air purified by the PPU to the heat exchanger; a pre-PPU cooler, located between the compressor system and the PPU, to cool the compressed air output from the compressor system and deliver the cooled compressed air to the PPU; The PPU comprises: a container connected between the compressor system and the heat exchanger, wherein an adsorption material bed is located in the container, wherein the adsorption material bed has at least one layer of adsorption material for removing water, carbon dioxide (CO2) and nitrous oxide (N2O) from the air, so that the N2O in the air output of the PPU is below a first preselected threshold; and The ASU system is configured such that, in response to a determination that a problem exists with the pre-PPU cooler that causes the pre-PPU cooler to trip or requires the pre-PPU cooler to be taken offline, the ASU system can still operate at full capacity even if N2O in the air output of the PPU exceeds a first preselected threshold.

18. The ASU system of claim 17, comprising an air separation tower assembly positioned to receive the air from the heat exchanger.

19. The ASU system of claim 17 , wherein the ASU system is configured to, in response to a determination that a problem exists with the pre-PPU cooler that causes the pre-PPU cooler to trip, operate the ASU system at full capacity until the air output of the PPU exceeds a second preselected threshold that is greater than the first preselected threshold, the second preselected threshold being associated with a CO breakthrough condition, even if N2O in the air output of the PPU exceeds the first preselected threshold; in: The first preselected threshold is in the range of 0-0.2 ppm N2O, and the second preselected threshold is in the range of 0.2-0.32 ppm N2O, or The first preselected threshold is selected to remove 20%-100% of the N2O from the air delivered to the PPU, and the second preselected threshold is selected to remove less than 50% of the N2O from the air delivered to the PPU.

20. The ASU system of claim 17, wherein the ASU system is configured to operate at full capacity for a preselected duration not exceeding 14 days even if N2O in the air output of the PPU exceeds the first preselected threshold and is below a second preselected threshold associated with CO2 breakthrough.

21. The ASU system of claim 17, wherein the ASU system is configured to operate at full capacity for a preselected duration not exceeding 7 days even if N2O in the air output of the PPU exceeds the first preselected threshold and is below a second preselected threshold associated with CO2 breakthrough.

22. The ASU system of claim 17, wherein the ASU system is configured to operate at full capacity for a preselected duration not exceeding 2 days even if N2O in the air output of the PPU exceeds the first preselected threshold and is below a second preselected threshold associated with CO2 breakthrough.

23. The ASU system of claim 20, wherein the ASU system is configured to operate the ASU system at full capacity without a redundant pre-PPU cooler operating even if NO in the air output of the PPU exceeds the first preselected threshold to cool the compressed air of the compressor system before sending the compressed air to the PPU to replace the pre-PPU cooler, wherein the pre-PPU cooler is determined to have the problem that causes the pre-PPU cooler to trip or require the pre-PPU cooler to be taken offline.

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