Vacuum pressure swing adsorption (VPSA) system with oxygen compressor

Abstract

The present invention relates to a vacuum pressure swing adsorption (VPSA) system with an oxygen compressor. A vacuum pressure swing adsorption (VPSA) system for oxygen production is provided. The VPSA system comprises a centrifugal oxygen compressor configured to be directly driven by a high speed permanent magnet or high speed induction motor with magnetic bearing suspension and the high speed permanent magnet or high speed induction motor has a speed controlled by a variable frequency drive. The VPSA system is further configured to enter a shutdown mode when an oxygen leak on a labyrinth seal is detected. The oxygen leak on the labyrinth seal is indicated when a seal gas system pressure in the centrifugal oxygen compressor is less than a safe operating threshold pressure and / or when an oxygen concentration in the seal gas system is higher than an oxygen concentration threshold.

Description

Technical Field

[0001] This disclosure relates to the field of air separation via vacuum pressure swing adsorption (VPSA), and more specifically to a VPSA system or arrangement designed to produce an oxygen product stream, the system or arrangement having three (3) centrifugal compressors, including an oxygen compressor configured to be directly driven by a high-speed permanent magnet or a high-speed induction motor with magnetic levitation bearings, and the oxygen compressor having a speed controlled by a variable frequency drive. Background Technology

[0002] In existing VPSA systems for oxygen production, centrifugal blowers with direct-drive motors are frequently used to compress the feed air stream to be delivered to the adsorption bed and to vacuum extract residual gases during adsorption bed regeneration. Over the years, the use of centrifugal compressors with direct-drive motors for compressing feed air streams and extracting residual gases has been greatly improved to provide higher efficiency and quieter operation. However, the design and operation of centrifugal compressors with direct-drive motors face many technical challenges and safety hazards, especially when used to compress oxygen-enriched gases or other flammable and explosive gases.

[0003] Specifically, the mechanical bearings of traditional centrifugal compressors or blowers rely on lubricating oil for lubrication and cooling. This ensures the smooth operation of the compressor or blower, but it also introduces the risk of oil seal leakage. Oil seal failure in centrifugal machinery not only leads to wasted lubricating oil, but in more serious cases, if the lubricating oil comes into contact with high-temperature or flammable substances, it may cause a fire or explosion.

[0004] Furthermore, oxygen leakage into the motor housing of an oxygen-producing VPSA system is a serious potential problem. Specifically, any oxygen leakage from the oxygen-enriched product stream into the motor housing of the oxygen compressor or blower used in the VPSA system not only reduces the efficiency of the VPSA equipment but may also exacerbate the risk of fire or explosion due to the increased oxygen concentration in contact with the lubricating oil. Therefore, dedicated oxygen compressors and blowers are often required, employing oxygen-safe lubricants to reduce the risk of fire. Using such dedicated oxygen compressors and blowers typically involves higher capital costs, higher operating / maintenance costs, lower operating efficiency, and is often noisier than centrifugal compressors.

[0005] For example, maintenance costs for conventional oxygen compressors are driven higher because critical spare parts (such as bearings, seals, and lubricants) need to be replaced at shorter intervals and often require a full overhaul or replacement every few years. In addition to the additional maintenance costs, such frequent repairs and / or replacements increase downtime for the VPSA system and adversely affect its availability and reliability.

[0006] Improvements to oxygen-generating VPSA systems are needed to reduce the safety risks associated with oxygen leaks, while also improving their efficiency, availability, reliability, and operation. Such improvements should also reduce the capital, operating, and maintenance costs associated with the oxygen compressors or blowers in these VPSA systems. Summary of the Invention

[0007] In a broader sense, this invention represents a safety feature in an oxygen-generating VPSA system comprising a centrifugal oxygen compressor configured to be directly driven by a high-speed permanent magnet or a high-speed induction motor with magnetic levitation bearings. The safety feature causes the centrifugal oxygen compressor to enter a shutdown mode when an oxygen leak is detected on the labyrinth seal. An oxygen leak on the labyrinth seal can be indicated when the pressure in the sealing gas system of the centrifugal oxygen compressor is below a safe operating threshold pressure and / or when the oxygen concentration in the sealing gas system is above an oxygen concentration threshold.

[0008] More specifically, the present invention can be characterized as a vacuum pressure swing adsorption (VPSA) system for gas separation, the system comprising: (i) a plurality of adsorption containers, each containing at least one adsorbent material; (ii) a product buffer container configured to receive one or more effluent streams from the plurality of adsorption containers; and (iii) a feed centrifugal compressor configured to be directly driven by a first high-speed permanent magnet or high-speed induction motor having a magnetic levitation bearing, the first high-speed permanent magnet or high-speed induction motor having a speed controlled by a frequency converter driver, and the feed centrifugal compressor... The compressor is configured to compress the feed stream; (iv) a vacuum centrifugal compressor configured to be directly driven by a second high-speed permanent magnet or high-speed induction motor having a magnetic levitation bearing, and the second high-speed permanent magnet or high-speed induction motor having a speed controlled by a variable frequency drive, and the vacuum centrifugal compressor is also configured to vent residual streams received from one or more adsorption containers among a plurality of adsorption containers; (v) a product centrifugal compressor configured to be directly driven by a third high-speed permanent magnet or high-speed induction motor having a magnetic levitation bearing, and the third high-speed permanent magnet or high-speed induction motor having a speed controlled by a variable frequency drive, and the vacuum centrifugal compressor is also configured to vent residual streams received from one or more adsorption containers among a plurality of adsorption containers; The system includes: (vi) a plurality of valves for directing the flow of the feed stream to at least one of the plurality of adsorption containers, directing the flow of the effluent stream from at least one of the plurality of adsorption containers to the product buffer container, and directing the flow of the residual stream from at least one of the plurality of adsorption containers; (vii) a controller configured to open and / or close the plurality of valves to control the flow of the feed stream to at least one of the plurality of adsorption containers, and directing the flow of the effluent stream from at least one of the plurality of adsorption containers to the product buffer container during an adsorption cycle, and directing the flow of the residual stream from at least one of the plurality of adsorption containers during a regeneration cycle; and (viii) the controller is further configured to receive data signals relating to conditions in the system and to control the speeds of the feed centrifugal compressor and associated first motor, the vacuum centrifugal compressor and associated second motor, and the product centrifugal compressor and associated third motor in response to the conditions in the system. Multiple adsorption containers are each configured for cyclic operation between adsorption and regeneration cycles.

[0009] In some embodiments of this VPSA system, the product centrifugal compressor preferably includes a centrifugal impeller, a volute, a backplate, a labyrinth seal, a purge gas circuit, a sealing gas system, and multiple sensors, including one or more pressure sensors and an oxygen concentration sensor. At least one of the pressure sensors and the oxygen concentration sensor may be located within the sealing gas system. The product centrifugal compressor is configured to automatically shut down when the condition of the VPSA system indicates an excessive oxygen leak or other potential safety issues, such as when the pressure in the sealing chamber behind the labyrinth seal falls below a first threshold pressure or the oxygen concentration in the sealing gas system exceeds a first threshold concentration. Many embodiments of the product centrifugal compressor in this VPSA system also include a purge gas circuit, and the product centrifugal compressor is configured to purge using a purge gas stream of nitrogen, air, or other inert gas mixture after the product centrifugal compressor is shut down and / or during its startup.

[0010] Preferably, in most embodiments of this VPSA system, the adsorbent material may include zeolite molecular sieve (ZMS), and more preferably at least one layer of 13X zeolite molecular sieve, or at least one layer of lithium-exchanged zeolite (LiX), or at least one layer of calcium-exchanged zeolite (CaX), or a layer of both 13X zeolite molecular sieve and lithium-exchanged zeolite (LiX), or a layer of both 13X zeolite molecular sieve and calcium-exchanged zeolite (CaX).

[0011] The present invention can also be characterized as a centrifugal compressor configured to compress an oxygen-enriched product stream and driven by a high-speed permanent magnet or a high-speed induction motor with magnetic levitation bearings. The centrifugal compressor includes: a centrifugal impeller; a volute; a back plate; a shroud; and a labyrinth seal. The centrifugal compressor is characterized by having a plurality of sensors, including an oxygen concentration sensor disposed within a sealed gas system and one or more pressure sensors disposed on the high-pressure side and the low-pressure side of the labyrinth seal (e.g., within the sealed gas system). The operation and speed of the centrifugal compressor are configured to be controlled in response to data signals from the plurality of sensors, and more specifically, to automatically deactivate when data signals from the sensors indicate an oxygen leak at the labyrinth seal.

[0012] This invention can be broadly characterized as a method for controlling a centrifugal product compressor configured to compress an oxygen-enriched product stream, wherein the method comprises the steps of: (a) establishing a baseline pressure threshold for the centrifugal product compressor using measurements from multiple sensors, the baseline pressure threshold including a permissible start-up pressure threshold and a safe operating threshold pressure; (b) initiating operation of the centrifugal product compressor to compress the oxygen-enriched product stream; (c) detecting the pressure of the sealed chamber during operation of the centrifugal product compressor; and (d) controlling the centrifugal product compressor to enter a shutdown mode when the pressure of the sealed chamber is less than the safe operating threshold pressure.

[0013] As described above, the centrifugal product compressor is configured to be driven by a high-speed permanent magnet or a high-speed induction motor with magnetic levitation bearings, and the centrifugal product compressor further includes: a centrifugal impeller; a volute; a back plate; a shroud; a labyrinth seal; and multiple sensors, including an oxygen concentration sensor and one or more pressure sensors disposed within the sealed gas system. Preferably, the step of starting the centrifugal product compressor to compress the oxygen-enriched product stream can only occur when the sealed gas chamber pressure is at or above the start-up permissible threshold pressure. Furthermore, additional pressure thresholds determined or established during this method, which can also be used to control the operation of the centrifugal product compressor, may include a minimum pressure threshold and a maximum pressure threshold using measurements from multiple sensors. Attached Figure Description

[0014] It is believed that the specific embodiments and claims followed will be better understood when viewed in conjunction with the accompanying drawings, in which:

[0015] Figure 1 A general schematic diagram illustrating an oxygen-generating vacuum pressure swing adsorption (VPSA) system according to an embodiment of the present invention is shown; and

[0016] Figure 2 A cross-sectional view of a centrifugal product compressor suitable for an oxygen-producing VPSA system is shown. Detailed Implementation

[0017] Now turn to the attached image, and specifically... Figure 1A general schematic diagram illustrating an oxygen-generating vacuum pressure swing adsorption (VPSA) system is shown. The illustrated VPSA system (10) comprises seven main subsystems, including: (i) an intake subsystem; (ii) an adsorber subsystem comprising at least two adsorption containers (12, 14) containing selected adsorbent material (16) and associated valves (24A, 24B, 34A, 34B, 36, 44A, 44B); (iii) a residual gas venting subsystem; (iv) a product buffer container (18) and associated valves (45) and instrumentation; (v) an oxygen compression subsystem; (vi) a control subsystem (70); and (vii) a liquid oxygen backup subsystem (80). Each adsorption container (12, 14) is configured to be controlled by the control subsystem (70) for cyclic operation between adsorption and regeneration cycles.

[0018] In the illustrated embodiment of the oxygen-generating VPSA system, the feed air stream (50) is filtered or otherwise pretreated in a pretreatment unit (52) and subsequently compressed in a feed centrifugal compressor (20), which is configured to be directly driven by a first high-speed permanent magnet or high-speed induction motor (22), preferably with magnetic levitation bearings. The speed of the motor (22) is controlled by a frequency converter (not shown). The compressed air stream (23) is optionally cooled in a heat exchanger or cooler (not shown) and directed to adsorption containers (12, 14) via high-performance switching valves (24A, 24B), each adsorption container having one or more layers of adsorbent material (16). The oxygen-enriched effluent stream (43) exits the adsorption containers (12, 14) via high-performance switching valves (44A, 44B), while pressure equalization valves (36) are disposed between the adsorbent containers and operated to equalize the pressure between the adsorbent containers, as required during purging and equalization steps.

[0019] During the regeneration of the adsorbent material (16) in the adsorption containers (12, 14), residual gases (35), including nitrogen and other undesirable contaminants, are desorbed from the adsorbent material (16) and vented from the adsorption containers (12, 14) via high-performance switching valves (34A, 34B). The regeneration of the adsorbent material (16) and the venting of the adsorption containers (12, 14) are driven by a vacuum centrifugal compressor (30), which is configured to be directly driven by a second high-speed permanent magnet or high-speed induction motor (32), also having magnetic levitation bearings and controlled via a frequency converter. The vented residual gas (35) is guided through a silencer (33) and exits the system.

[0020] The oxygen-enriched effluent (43) is directed via a valve (45) to a product buffer container (18), which is configured to receive one or more effluent streams (43) from multiple adsorption containers (12, 14). The purpose of the product buffer container (18) is to compensate for fluctuations in the oxygen flow during switching or circulation processes of the adsorber containers. The oxygen-enriched stream (48) is controllably directed from the product buffer container (18) to an oxygen compression subsystem, which includes a product centrifugal compressor (40) configured to be driven by another high-speed permanent magnet or high-speed induction motor (42) with magnetic levitation bearings and to produce a compressed oxygen-enriched product stream (60).

[0021] The control subsystem (70) includes a programmable logic controller (PLC) configured to open and / or close multiple valves (24A, 24B, 34A, 34B, 36, 44A, 44B, 45) to control the flow of compressed air (23) to the adsorption containers (12, 14), and to direct the flow of oxygen-enriched effluent (43) from the adsorption containers (12, 14) to the product buffer container (18) during the adsorption cycle, and to direct the flow of residual stream (33) from at least one of the multiple adsorption containers (12, 14) during the regeneration cycle. The control subsystem (70) is also configured to receive data signals from various sensors and instruments in the VPSA system (10) to detect and / or determine the operating conditions in the VPSA system (10), and to control the speed of the motor in response to the conditions in the VPSA system and the measurements from the associated sensors and instruments.

[0022] In operation, the VPSA system (10) is fully automated and can be operated locally or remotely (i.e., unattended). The controller subsystem may also include an integrated load tracking mode that automatically adjusts the output to the changing gas demands of the end-user. The VPSA system also includes an integrated liquid oxygen backup subsystem that allows for peak shaving and also delivers oxygen to the end-user in the event of a shutdown of the centrifugal product compressor or the entire VPSA system.

[0023] The basic VPSA process uses selective adsorbents to remove at least one component from the feed gas (such as air) using four basic process steps or stages: (1) adsorption; (2) depressurization; (3) purging; and (4) repressurization. For oxygen-generating VPSA systems, the adsorbent material used in the VPSA system is capable of selectively adsorbing components that are more readily adsorbed, such as nitrogen, water, carbon dioxide, or other contaminants from the compressed air stream, while recovering oxygen from the effluent stream. The purity of the oxygen stream is typically in the range of 80% to 95%.

[0024] In a preferred oxygen-generating VPSA system, two adsorption vessels are each configured for cyclic operation between adsorption and regeneration cycles. When the feed compressor begins loading one of the adsorption beds, the first adsorption bed (within the adsorption vessel) is pressurized and the adsorption process begins. During this initial step or phase, the first adsorption bed may be simultaneously pressurized at the inlet side by compressed air from the feed compressor and at the outlet side by equalization gas from the other adsorption bed (i.e., the second adsorption bed). In other embodiments, an oxygen-enriched stream from a product buffer vessel may also be introduced to the outlet side of the first adsorption bed. The oxygen-enriched stream from the product buffer vessel helps sharpen the adsorption front and also increases the bed pressurization rate.

[0025] At some point during the adsorption phase, the first adsorption bed is exposed to a substantially constant pressure while oxygen is recovered in the effluent. Near the end of the adsorption phase, a portion of the oxygen-enriched effluent can be transferred as purge gas to the second adsorption bed. The purity of the oxygen-enriched effluent remains relatively constant, and the adsorption phase ends after a predetermined duration and / or before any penetration of undesirable elements or compounds occurs.

[0026] The depressurization phase preferably begins when the feed compressor unloads, and the lower-purity gas remaining in the first adsorption bed is guided to another or a second adsorption bed via an equalization valve. Midway through bed equalization, the vacuum compressor switches and begins to vent the residual gas remaining in the first adsorption bed. As the vacuum compressor continues to vent the first adsorption bed from which nitrogen, water, carbon dioxide, and other contaminants have been desorbed, the pressure in the first adsorption bed continues to decrease.

[0027] After depressurization, the first adsorption bed is purged. During this purging phase, the vacuum compressor continues to evacuate the first adsorption bed, while an oxygen-enriched gas stream from the product buffer container purges through the first adsorption bed and is evacuated by the vacuum compressor along with any residual gas.

[0028] The final stage is repressurization. During this phase, the vacuum compressor continues to vent the first adsorption bed, while the feed compressor unloads and the pressures in both adsorption beds are equalized. During this repressurization phase, the pressure in the first adsorption bed increases because more equilibrium gas flows into it than leaves the vented bed. At the end of the repressurization phase, the vacuum compressor switches to the second adsorption bed, and the feed compressor also switches from unloading to fully reloading the first adsorption bed.

[0029] VPSA system adsorbent

[0030] Preferred adsorbent materials include commercially available adsorbent materials such as 13X zeolite molecular sieves or advanced adsorbents such as lithium-exchanged zeolite (LiX) or calcium-exchanged zeolite (CaX) or mixed cation adsorbents. These adsorbent materials are capable of selectively adsorbing more readily adsorbable components, such as nitrogen, water, carbon dioxide, or other contaminants, from the compressed air stream, while recovering less readily adsorbable components, i.e., oxygen in the effluent stream. Current and preferred stratification of adsorbent materials in oxygen-generating VPSA systems includes a short layer of 13X adsorbent to remove water and carbon dioxide from the feed air, followed by a longer layer of LiX adsorbent to separate nitrogen from the compressed air stream.

[0031] The zeolite molecular sieve is preferably zeolite X, including LSX. More preferably, the zeolite contains lithium cations, and wherein the amount of lithium, on an equivalence basis, is at least 90%, and preferably at least 95%. The zeolite molecular sieve is advantageously used in agglomerated form, wherein the average particle size of the agglomerates is in the range of 0.4 mm to 2.5 mm, and preferably in the range of 1.3 mm to 1.8 mm. The agglomerates may contain a binder or may not contain a binder at all. In a particularly preferred case, the zeolite molecular sieve is of the LSX type, containing at least 95% lithium cations on an equivalence basis. The zeolite is agglomerated with up to 12% by weight of a binder and has an average particle size in the range of 1.3 mm to 1.8 mm.

[0032] VPSA System Security Control

[0033] To help understand the safety controls of a VPSA system, it is helpful to understand the basic construction or structural layout of a centrifugal product compressor. Figure 2 A partial cross-sectional view of a typical centrifugal product compressor suitable for this oxygen-generating VPSA system is shown. As shown, the centrifugal product compressor 40 includes: a centrifugal impeller 144; a volute 145; a back plate 146; a shroud 148; and a labyrinth seal 150. In the illustrated compressor, the labyrinth seal 150 generally defines a high-pressure side and a low-pressure side of the labyrinth seal. The high-pressure side includes the impeller, shroud, and volute, where the oxygen product stream is compressed. The low-pressure side includes a gap between the back plate and the motor and also includes a sealed gas system having a sealed chamber 156 and a purge gas circuit 155. The illustrated compressor 40 also includes a plurality of sensors, including an oxygen concentration sensor 158 disposed in the sealed gas system (i.e., adjacent to, upstream of, or possibly within the sealed chamber), and one or more pressure sensors 157A, 157B disposed in the gas sealing system on the high-pressure side of the labyrinth seal and on the low-pressure side of the labyrinth seal 150. The pressure sensor on the low-pressure side of the labyrinth seal is configured to measure the pressure of the sealed gas chamber, while the pressure sensor on the high-pressure side of the labyrinth seal is configured to at least measure the pressure of the compressed oxygen-rich product stream.

[0034] Using measurements from multiple sensors in the centrifugal product compressor, including an oxygen concentration sensor and one or more pressure sensors, the operation and speed of the centrifugal product compressor are configured to be controlled in response to data signals generated from the sensors. More specifically, the centrifugal product compressor is configured to automatically shut down when multiple sensors indicate the presence of oxygen leakage at the labyrinth seal.

[0035] More specifically, controlling the oxygen-generating VPSA system to ensure the safe operation of the centrifugal product compressor (i.e., the oxygen compressor) involves two related control schemes using measurements from an oxygen concentration sensor and one or more pressure sensors within the centrifugal product compressor. The first of these related control schemes involves establishing baseline performance for the centrifugal product compressor, and more specifically, establishing baseline pressure thresholds for the labyrinth seal. During commissioning of the centrifugal product compressor and / or subsequent periodic commissioning, a series of tests and / or evaluations are performed to determine multiple seal chamber pressure thresholds, including: (i) the permissible start-up pressure threshold; (ii) the safe operating threshold pressure; (iii) the minimum pressure threshold; and (iv) the maximum pressure threshold.

[0036] The permissible start-up pressure threshold is the pressure range within the sealed chamber on the low-pressure side of the labyrinth seal that is required to start or initiate the centrifugal product compressor. If the pressure in the sealed chamber is outside this permissible start-up pressure range, it is generally considered unsafe to start or operate the centrifugal product compressor. The permissible start-up pressure threshold or pressure range is generally a function of the desired or target operating pressure of the centrifugal compressor (i.e., the pressure of the oxygen-enriched product stream) and can be determined empirically or set according to the compressor design.

[0037] The minimum and maximum pressure thresholds within the sealed gas chamber are also functions of the centrifugal compressor's operating pressure and the permissible oxygen concentration in the sealed gas system. For example, the maximum pressure threshold for the sealed gas chamber could be the pressure at which the leakage oxygen concentration in the sealed gas system (e.g., in the gap between the labyrinth seal and the motor) is similar to the oxygen concentration in air, or 21%, while the minimum pressure threshold for the sealed gas chamber could be the pressure at which the leakage oxygen concentration increases, for example, equal to or close to 35%.

[0038] From an oxygen leakage safety perspective, the safe operating pressure threshold pressure within the sealed chamber on the low-pressure side of the labyrinth seal is the most critical pressure threshold and is also a function of the centrifugal compressor's operating pressure and the permissible oxygen concentration in the sealed gas system. The safe operating pressure threshold represents the pressure within the sealed chamber where a significant safety hazard exists due to leaking oxygen concentration. Such unsafe oxygen concentrations are generally values ​​known to those skilled in the art and depend to some extent on the specific design of the centrifugal product compressor and the materials used therein; however, for illustrative purposes only, for an oxygen-generating VPSA system, the leaking oxygen concentration in the gap between the labyrinth seal and the motor can be approximately 50%.

[0039] The second of the two safety-related control schemes involves the startup and operation of the VPSA system, as well as monitoring the pressure in the centrifugal product compressor, including the pressure in the sealed gas chamber and the oxygen-enriched product flow, and comparing those measured pressures (or pressure differences) with previously determined pressure thresholds.

[0040] During startup of the centrifugal product compressor, this control scheme performs an "operation" process, in which a purge stream or a mixture of air, nitrogen, or other inert gases passes through the centrifugal product compressor. Following the "operation" process, the VPSA controller then directs an oxygen-enriched stream from the product buffer container to the centrifugal product compressor while continuously monitoring the pressure in the sealed chamber and comparing it to a safe operating threshold pressure. When the pressure detected in the sealed chamber of the centrifugal product compressor is lower than the determined safe operating pressure threshold, the centrifugal product compressor is commanded or controlled to enter a shutdown mode. Conversely, when the sealed chamber pressure is at or above the safe operating threshold pressure, operation of the centrifugal product compressor continues. In shutdown mode, the centrifugal product compressor is subsequently purged by redirecting the airflow or a mixture of air, nitrogen, or other inert gases through the centrifugal product compressor for a set time period.

[0041] In addition, the pressure detected in the sealed chamber of the centrifugal product compressor is compared with the minimum and maximum pressure thresholds. If the pressure detected in the sealed chamber of the centrifugal product compressor is not between the minimum and maximum pressure thresholds, the VPSA system controller may adjust the sealing gas flow or take other remedial actions (including shutdown) that may be necessary for safe operation of the centrifugal product compressor within the desired or target sealed chamber pressure range. Alternatively, if necessary, the VPSA system controller may also adjust the speed of the motors driving the feed compressor, vacuum compressor, and / or centrifugal product compressor.

[0042] During the startup and operation of the VPSA system, the oxygen concentration within the sealing gas system is also measured to monitor labyrinth seal performance. If labyrinth seal performance is deteriorating or appears to be deteriorating, the VPSA system operator can take remedial measures such as maintenance scheduling and / or modifying the aforementioned pressure thresholds.

[0043] Furthermore, in some embodiments of this oxygen-generating VPSA system, if and when the centrifugal product compressor is commanded or controlled to enter a shutdown mode, the VPSA controller may also activate the liquid oxygen backup system to ensure a continuous supply of oxygen products to the end-user customer.

[0044] Although the system and associated methods have been described with reference to preferred embodiments, it should be understood that various additions, changes and omissions may be made without departing from the spirit and scope of the system, apparatus and methods shown in the appended claims.

Claims

1. A system for gas separation, comprising: Multiple adsorption containers, each containing at least one adsorption material; A product buffer container, the product buffer container being configured to receive one or more effluent streams from the plurality of adsorption containers; A feed centrifugal compressor, the feed centrifugal compressor being configured to be directly driven by a first high-speed permanent magnet or a high-speed induction motor having a magnetic levitation bearing, the first high-speed permanent magnet or high-speed induction motor having a speed controlled by a frequency converter, and the feed centrifugal compressor being configured to compress the feed flow; A vacuum centrifugal compressor, the vacuum centrifugal compressor being configured to be directly driven by a second high-speed permanent magnet or a high-speed induction motor having a magnetic levitation bearing, and the second high-speed permanent magnet or high-speed induction motor having a speed controlled by a frequency converter, and the vacuum centrifugal compressor being further configured to vent residual flow received from one or more of the plurality of adsorption containers; The product centrifugal compressor is configured to be directly driven by a third high-speed permanent magnet or a high-speed induction motor with magnetic levitation bearings, and the third high-speed permanent magnet or high-speed induction motor has a speed controlled by a frequency converter driver, and the product centrifugal compressor is also configured to compress an oxygen-enriched product stream received from the product buffer container. Multiple valves are provided for directing the flow of the feed stream to at least one of the multiple adsorption containers, directing the flow of the effluent stream from at least one of the multiple adsorption containers to the product buffer container, and directing the flow of the residual stream from at least one of the multiple adsorption containers. A controller configured to open and / or close the plurality of valves to control the flow of the feed stream to at least one of the plurality of adsorption vessels, and to direct the flow of the effluent stream from at least one of the plurality of adsorption vessels to the product buffer vessel during an adsorption cycle, and to direct the flow of the residual stream from at least one of the plurality of adsorption vessels during a regeneration cycle; and The controller is also configured to receive data signals regarding conditions in the system, and to control the speeds of the feed centrifugal compressor and its associated first motor, the vacuum centrifugal compressor and its associated second motor, and the product centrifugal compressor and its associated third motor in response to the conditions in the system. Each of the plurality of adsorption containers is configured for cyclic operation between the adsorption cycle and the regeneration cycle.

2. The system for gas separation according to claim 1, wherein the adsorbent material further comprises zeolite molecular sieve (ZMS).

3. The system for gas separation according to claim 2, wherein the adsorbent material further comprises at least one layer of 13X zeolite molecular sieve or at least one layer of lithium exchange zeolite (LiX) or a layer of both 13X zeolite molecular sieve and lithium exchange zeolite (LiX).

4. The system for gas separation according to claim 1, wherein the product centrifugal compressor further comprises a centrifugal impeller, a volute, a back plate, a labyrinth seal, a purge gas circuit, and a plurality of sensors, wherein the plurality of sensors include one or more pressure sensors and an oxygen concentration sensor.

5. The system for gas separation according to claim 4, wherein the product centrifugal compressor is configured to automatically shut down when the condition of the system indicates an oxygen leak at the labyrinth seal.

6. The system for gas separation according to claim 5, wherein at least one of the pressure sensors disposed within the product centrifugal compressor is configured to measure the pressure of a sealed chamber within the product centrifugal compressor, and the product centrifugal compressor automatically shuts down when the pressure of the sealed chamber is less than a safe operating threshold pressure.

7. The system for gas separation according to claim 5, wherein the oxygen concentration sensor disposed within the sealed gas system of the product centrifugal compressor is configured to measure the oxygen concentration within the sealed gas system, and the product centrifugal compressor is deactivated when the oxygen concentration is higher than an oxygen concentration threshold.

8. The system for gas separation according to claim 6 or claim 7, wherein the product centrifugal compressor is configured to purge with a purge gas stream when the product centrifugal compressor is deactivated.

9. The system for gas separation according to claim 4, wherein the product centrifugal compressor is configured to purge with a purge gas stream when the product centrifugal compressor is started.

10. The system for gas separation according to claim 8 or 9, wherein the purge gas stream is a stream of air, nitrogen, or an inert gas mixture.

11. A centrifugal compressor configured for compressing an oxygen-enriched product stream and directly driven by a high-speed permanent magnet or a high-speed induction motor having magnetic levitation bearings, the centrifugal compressor comprising: Centrifugal impeller; Snail shell; Back panel; Protective shield; And a labyrinth seal, and wherein the centrifugal compressor is characterized by: Multiple sensors, including an oxygen concentration sensor disposed within the sealed gas system, and one or more pressure sensors disposed on the high-pressure side of the labyrinth seal and on the low-pressure side of the labyrinth seal, or at other locations in the sealed gas system. and The operation and speed of the centrifugal compressor are configured to be controlled in response to data signals from the plurality of sensors; and The centrifugal compressor is configured to automatically shut down when data signals from the plurality of sensors indicate an oxygen leak at the labyrinth seal.

12. The centrifugal compressor of claim 11, wherein at least one of the one or more pressure sensors is configured to measure the pressure of the sealed chamber, and the centrifugal compressor automatically shuts down when the pressure of the sealed chamber is less than a safe operating threshold pressure.

13. The centrifugal compressor of claim 11, wherein the oxygen concentration sensor is configured to measure the oxygen concentration within the sealed gas system, and the centrifugal compressor is configured to deactivate when the oxygen concentration is above an oxygen concentration threshold.

14. The centrifugal compressor of claim 11, wherein the centrifugal compressor is configured to allow start-up when the pressure of the sealing gas system is at or above the start-up permissible threshold pressure.

15. The centrifugal compressor of claim 11, wherein when the centrifugal compressor is started and / or stopped, a purge airflow is directed through the centrifugal compressor.

16. The centrifugal compressor of claim 15, wherein the purge airflow is directed through the centrifugal impeller on the high-pressure side of the labyrinth seal and / or the sealing chamber on the low-pressure side of the labyrinth seal.

17. The centrifugal compressor of claim 16, wherein the purge gas stream is a stream of air, nitrogen, or an inert gas mixture.

18. A method for controlling a centrifugal product compressor, the centrifugal product compressor being configured to compress an oxygen-enriched product stream, the centrifugal product compressor being configured to be driven by a high-speed permanent magnet or a high-speed induction motor having magnetic levitation bearings, and the centrifugal product compressor further comprising: Centrifugal impeller; Snail shell; Back panel; Protective shield; A labyrinth seal and multiple sensors, the multiple sensors including an oxygen concentration sensor disposed within a sealed gas system and one or more pressure sensors disposed on the high-pressure side and the low-pressure side of the labyrinth seal, wherein the method includes the following steps: (a) Using measurements from the plurality of sensors to establish a baseline pressure threshold for the labyrinth seal, the baseline pressure threshold including a permissible start-up pressure threshold and a safe operating threshold pressure; (b) Activate the start-up mode of the centrifugal product compressor to compress the oxygen-enriched product stream; (c) Detecting the pressure of the sealing gas system during operation of the centrifugal product compressor; and (d) When the pressure of the sealed gas system is less than the safe operating threshold pressure, control the centrifugal product compressor to start the shutdown mode.

19. The method of claim 18, wherein the step of initiating the operation of the centrifugal product compressor to compress the oxygen-enriched product stream further comprises: When the pressure of the sealed gas system is at or above the start-up permission threshold pressure, the operation of the centrifugal product compressor is initiated to compress the oxygen-enriched product stream.

20. The method of claim 18, wherein the step of establishing a baseline pressure threshold further comprises: The minimum and maximum pressure thresholds are established using measurements from the multiple sensors.

21. The method of claim 18, further comprising the step of purging the centrifugal product compressor when the shutdown mode is activated.

22. The method of claim 18, further comprising the step of purging the centrifugal product compressor before activating the start-up mode.

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