CN116600876A - System and method for concentrating gas - Google Patents

Abstract

Systems and methods are provided that achieve the same or better performance levels by using lower operating flow rates, pressures, and/or optimized flow profiles within the system. This extends the life of the system components and reduces energy consumption. In one embodiment, a gas separation (or sieve) bed for separating gas components is provided that has lower flow and pressure requirements than conventional beds. The sieve bed includes, for example, a diffuser having a low solid area in cross section and a maximum open area for flow while providing sufficient mechanical properties to contain the sieve material and support the filter media. In another embodiment, a system and method are provided having an indicator when a component has been repaired or repaired. This provides an indication of whether the component has been tampered with in any way. This allows the manufacturer to determine whether the component is being repaired, repaired or tampered with outside the manufacturer's domain.

Description

System and method for concentrating gas

Cross reference to related applications

The present application claims priority from U.S. provisional patent application serial No.63/052,694, filed on 7/16/2020, and U.S. provisional patent application serial No.63/212,920, filed on 21/2021 (attorney docket No. 12873-07156), entitled "system and method for concentrating gas (System and Method for Concentrating Gas)" (attorney docket No. 12873-07004).

The present application incorporates by reference the following patent applications: U.S. provisional patent application Ser. No.63/052,694 entitled "System and method for concentrating gas (System and Method for Concentrating Gas)" (attorney docket No. 12873-07004); U.S. provisional patent application Ser. No.63/052,700, entitled "System and method for concentrating gas (System and Method for Concentrating Gas)" (attorney docket No. 12873-07033); U.S. provisional patent application Ser. No.63/052,869 entitled "System and method for concentrating gas (System and Method for Concentrating Gas)" (attorney docket No. 12873-07041); U.S. provisional patent application Ser. No.63/052,533, entitled "System and method for concentrating gas (System and Method for Concentrating Gas)" (attorney docket No. 12873-07043); and U.S. provisional patent application serial No.63/052,647 entitled "method for managing a system of medical devices (System and Method for Managing Medical Devices)" (attorney docket No. 12873-07044), filed all over 16 days 7 in 2020; and U.S. provisional patent application Ser. No.63/212,920, entitled "System and method for concentrating gas (System and Method for Concentrating Gas)" (attorney docket No. 12873-07156) filed on day 21 of 6 in 2020.

Background

There are various applications for the separation of gas mixtures. For example, separation of nitrogen from atmospheric air may provide a highly concentrated source of oxygen. These various applications include providing high concentrations of oxygen to medical patients and flight personnel. It is therefore desirable to provide a system that separates a gas mixture to provide a concentrated product gas, such as a respiratory gas having a concentration of oxygen.

Several existing product gas or oxygen concentration systems and methods are disclosed, for example, in U.S. patent nos. 4,449,990, 5,906,672, 5,917,135, 5,988,165, 7,294,170, 7,455,717, 7,722,700, 7,875,105, 8,062,003, 8,070,853, 8,668,767, 9,132,377, 9,266,053, and 10,010,696, which are commonly assigned to Invacare Corporation (Elyria, ohio) and are incorporated herein by reference in their entirety.

Such systems are known to be stationary, transportable or portable. The fixation system is intended to remain in a position such as, for example, a bedroom or living room of a user. Transportable systems are intended to be moved from one location to another and typically include wheels or other mechanisms to facilitate movement. The portable system is intended to be carried by a user, such as for example via a shoulder strap or similar accessory.

As part of the separation and concentration process, gas concentration systems typically produce dynamic flow and pressure within their working components. These flows and pressures, while necessary, also affect the mechanical wear and life of the system components. In general, the higher the necessary flow and pressure within the system, the greater their impact on the mechanical wear and life of the system components. In addition, the higher the necessary flow and pressure within the system, the higher the amount of energy that needs to be expended to create the desired flow and pressure. What is desired is a system that addresses these and other aspects of a gas separation or concentration system.

In another aspect, the gas concentration system requires maintenance during its lifetime. Various gas separation components require replacement, repair or repair. Manufacturers need to know when such components are serviced outside the manufacturer's domain (domain). What is desired is a system that also addresses this aspect of the gas separation or concentration system.

Disclosure of Invention

Gas concentration systems and methods are provided. In one embodiment, a system and method are provided for achieving the same or better performance levels by using lower operating flow rates and pressures within the system. This extends the life of the system components and reduces energy consumption. In one embodiment, a gas separation (or sieve) bed for separating gas components is provided that has lower flow and pressure requirements than conventional beds. The sieve bed includes, for example, a diffuser having a low solid area in cross section and a maximum open area for flow while providing sufficient mechanical properties to contain the sieve material and support the filter media. This allows for efficient flow of gas into and out of the sieve bed, which reduces pressure losses and energy consumption, reduces dynamic and static pressure on the sieve bed material, and extends (improvers) the life of the sieve bed material and reduces the rate at which the sieve bed material mechanically fails. Other embodiments are also disclosed.

In another embodiment, a system and method are provided having an indicator (indicator) when a component has been repaired or repaired. This provides an indication of whether the component has been tampered with in any way. This allows the manufacturer to determine whether the component is being repaired, repaired or tampered with outside the manufacturer's domain. Unauthorized repair or repair can result in premature component wear and failure.

In yet another embodiment, a system and method are disclosed having a more uniform or optimized flow distribution and/or low velocity of gas entering the sieve bed material. The sieve bed cap and/or gas input interface is provided with flow modifying structures, baffles or protrusions within the flow chamber to more evenly distribute the flow and reduce the velocity of the gas flow into the sieve bed material. These structures, baffles and/or protrusions direct the incoming gas stream into the adjacent space within the interior chamber of the cap/interface to provide a more uniform flow distribution of the gas entering the screen material. By introducing gas more uniformly into the sieve bed material, thereby limiting or eliminating pockets of the sieve bed material that may not otherwise be reached by the gas as it is unevenly distributed as it enters the sieve bed material, the more uniform flow distribution increases sieve bed efficiency. In addition, the reduced gas flow velocity reduces mechanical abrasion and tear on the sieve bed material, which abrasion and tear result in pulverization and fluidization of the material.

It is an object to provide a more efficient gas separation system and method.

It is another object to provide a gas separation system and method having a lower flow rate and pressure.

It is another object to provide a gas separation system and method having a diffuser element with a low solid area in cross section, providing a large open area for flow.

It is another object to provide a gas separation system and method having a diffuser element with a low solid area in cross section, thereby providing a large open area for flow, while also providing sufficient mechanical properties to contain the screen material and support the filter media.

It is another object to provide a gas separation system and method having component(s) for providing at least one tamper indication.

It is another object to provide a gas separation system and method having at least one sieve bed with a tamper indicator.

It is another object to provide a gas separation system and method having at least one tamper resistant component.

It is another object to provide a gas separation system and method having at least one tamper resistant sieve bed.

Another object is to provide a gas separation system and method that distributes the flow into a desired profile to achieve a more uniform distribution of gas into the sieve bed.

It is another object to provide a gas separation system and method having an input device (e.g., cap or insert) for deflecting and/or adjusting the flow to a desired profile as the gas enters the sieve bed.

It is another object to provide a gas separation system and method that reduces the flow rate of gas into the sieve bed material to reduce wear and tear (e.g., pulverization, fluidization, etc.) of the sieve material.

These and other objects, features and advantages will become apparent after a review of the following description, drawings and claims.

Drawings

In the accompanying drawings, which are incorporated in and constitute a part of this specification, embodiments of the invention are illustrated, which together with a general description of the invention given above and the detailed description given below serve to illustrate the principles of this invention.

FIG. 1 illustrates one embodiment of a gas concentration system.

FIG. 2 is one embodiment of a pneumatic block diagram of a gas concentration system.

FIG. 3 is a block diagram of one embodiment of a gas separation or sieve bed.

Fig. 4A-4B illustrate a prior art filter tray for use with a gas separation bed.

Fig. 5A-5B illustrate perspective exploded views of one embodiment of a gas separation bed.

Fig. 6A-6B are various cross-sectional views of the gas separation bed embodiment of fig. 5A-5B.

Fig. 7A-7F illustrate various views of various embodiments of diffusers having honeycomb structures.

Fig. 8 illustrates a top view of a second embodiment of a diffuser having a cylindrical or straw-like structure.

Fig. 9-12 illustrate side elevation views of various embodiments of diffusers with different cross-sectional geometries and profiles.

Fig. 13 illustrates a partial cross-sectional view showing one embodiment of a tamper-resistant feature.

Fig. 14A-14B illustrate perspective and elevation views of one embodiment of a sifter-bed cap including a tamper-resistant feature.

Fig. 15A-15B illustrate additional embodiments of sieve bed caps with tamper resistant features.

Fig. 16A-16D illustrate yet another embodiment of a sifter-bed cap having tamper-resistant features.

17A-17I illustrate one embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 18A-18C illustrate various flow trajectories and distributions of the sieve bed cap embodiment of fig. 17A-17I.

Fig. 18D-18E illustrate various flow trajectories and distributions of the sieve bed cap embodiment of fig. 17A-17I, but without any flow modification structures.

Fig. 19A-19B illustrate another embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 20A-20C illustrate various flow trajectories and distributions of the sieve bed cap embodiment of fig. 19A-19C.

Fig. 21A-21D illustrate various views of another embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 22A-22D illustrate various views of another embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 23A-23D illustrate various views of another embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 24A-24D illustrate various views of another embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 25A-25D illustrate various views of another embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 26A-26D illustrate various views of another embodiment of a sieve bed cap for producing a desired flow profile.

Fig. 26E-26F illustrate various flow trajectories and distributions of the sieve bed cap embodiment of fig. 26A-26D.

Fig. 27A-27B illustrate various views of another embodiment of a sieve bed cap for producing a desired flow profile.

Each mechanical drawing is presented relative to scale unless otherwise indicated. That is, the size, positioning, and location of the components illustrated in each figure are shown to scale relative to each other, which may also include exaggerated scale.

Detailed Description

As described herein, when one or more components are described or illustrated as being connected, joined, attached, coupled, attached, or otherwise interconnected, such interconnection may be direct interconnection between the components, or may be indirect, such as through the use of one or more intermediate components. Further, as described herein, references to a member, component, or section should not be limited to a single structural member, component, element, or section, but may include an assembly of components, members, elements, or sections.

Embodiments of the present invention provide, for example, gas separation systems and methods having efficient flow of working gas into and out of the sieve bed, reduced pressure loss and energy consumption, lower dynamic and static pressures on the sieve bed material, and an extended life of the sieve material achieved by reducing the rate at which the sieve material mechanically and/or structurally fails. Efficient flow of the working gas also reduces noise created by the gas flow within the system. In one embodiment, the gas separation system comprises at least one sieve bed with a diffuser arranged to subdivide the flow in its cross section into smaller flow channels, thereby reducing turbulence and energy losses. The gas flow is substantially straightened by the diffuser and more energy is transferred to the intended direction of the gas flow. The diffuser also has a low solid area (e.g., low solidity) in cross-section and a high and/or maximum open area for flow while also providing sufficient mechanical properties to contain the screen material within the screen bed and support the filter media.

One embodiment of a gas separation system 100, which may be an oxygen concentration system, is illustrated in fig. 1. The system may be stationary, such as for example for use in a hospital or patient home. The system may also be non-stationary or mobile, such as for use by patients when they are not at home, for example. The system may be configured in a manner that allows the patient to carry the system, such as, for example, by shoulder straps or by an arrangement of the system including handles and wheels. Other moving configurations are also included.

The oxygen system 100 includes a housing 102, which housing 102 may be in one or more sections. The housing 102 includes a plurality of openings for the intake and discharge of various gases, such as, for example, the intake of indoor air and the discharge of nitrogen and other gases. The oxygen system 100 generally sucks in indoor air composed mainly of oxygen and nitrogen, and separates the nitrogen from the oxygen. Oxygen is stored in one or more internal or external storage tanks or product tanks and nitrogen is vented back to the indoor atmosphere. For example, oxygen may be vented to the patient through the tubing and nasal cannula through port 104. Alternatively, the oxygen may be vented to an oxygen cylinder filling device through a supplemental port, such as manufactured by Invacre Corp (Elyria, ohio, USA) And an example thereof is described in U.S. patent No.5,988,165, which is incorporated by reference.

Figure 2 illustrates one embodiment of an exemplary pneumatic block diagram of a gas concentration system using Pressure Swing Adsorption (PSA). The system may include a plurality of gas separation sieve beds 206a and 206b, a plurality of valves 204a, 204b, 204c, and 204d, one or more product tanks 208a, 208b, and an economizer valve/device 218. In this embodiment, the product tanks 208a, 208b are shown connected so that they act as one product tank, but may also be arranged to act as two product tanks. The system also includes a compressor/pump 203 and one or more filters 201 and a muffler 202.

The sieve beds 206a and 206b are filled with a physical separation medium or material. The separation material selectively adsorbs one or more adsorbable components and passes one or more non-adsorbable components of the gas mixture. In general, the physical separation material is a molecular sieve having pores of uniform size and substantially the same molecular size. These pores selectively adsorb molecules according to molecular shape, polarity, saturation, and the like. In one embodiment, the physical separation medium is an aluminosilicate composition having 4 to 5ANG (angstroms) pores. More particularly, the molecular sieve is a sodium or calcium form of aluminosilicate, such as a type 5A zeolite. Alternatively, the aluminosilicate may have a higher silica to alumina ratio, larger pores, and affinity for polar molecules (e.g., 13x zeolite). The zeolite adsorbs nitrogen, carbon monoxide, carbon dioxide, water vapor and other significant amounts of components of air. Other types of separation media may also be used to adsorb nitrogen from ambient or indoor air. In addition, more than two sieve beds may be used. In other embodiments, the sieve beds 206a and 206b may be structurally integrated with one or more product tanks 208a and 208b, such as described in U.S. patent No.8,668,767, which is fully incorporated herein by reference for this and other features.

In operation, as shown by the solid line in fig. 2, during an exemplary fill cycle of the separation bed 206a, the pump/compressor 203 draws indoor air through the filter 201 and to the valve 204d and separation bed 206a (separation bed 206a produces oxygen at its output) and through the valve 210a into the product tanks 208a, 208b. Pump/compressor 203 supplies up to about 32 psi of air to the sieve bed during the filling stage. Other operating pressure ranges include about 15-32 psi. Valves 210a and 210b may be check valves or any other similarly functioning valves that allow unidirectional flow.

While the separation bed 206a is undergoing a fill cycle, the separation bed 206b may be undergoing a purge cycle to vent any nitrogen from the previous fill cycle. During the purge cycle, the previously pressurized separation bed 206b discharges nitrogen through valve 204a and out through muffler 202 to the atmosphere. The separation bed 206a is pressurized from its fill cycle. During the purge cycle, a quantity of oxygen from the separation bed 206a or product tanks 208a, 208b may be fed into the separation bed 206b to pre-load or pre-sufficiently exit the bed 206b with oxygen, as controlled by the optional bleed valve 212 and fixed orifice 214 shown in dashed lines in fig. 2.

As indicated by the dotted line in fig. 2, once separation bed 206a has been packed and/or separation bed 206b has been purged, control system 220 switches valves 204a, 204b, 204c, and 204d so that separation bed 206b enters the packing cycle and separation bed 206a enters the purge cycle. In this state, the pump 203 directs the indoor air into the separation bed 206b (the separation bed 206b produces oxygen at its output) and through the valve 210b into the product tanks 208a, 208b. During a purge cycle, a quantity of oxygen from the separation bed 206b or product tanks 208a, 208b may be fed into the separation bed 206a to be preloaded with oxygen or pre-fully off the bed 206a, with oxygen now flowing in the opposite direction compared to the previous cycle. The illustrated system also includes an exemplary pressure equalization valve 216 that equalizes the pressure in the two separate beds prior to a purge/fill cycle change. Notably, not all embodiments of PSA systems require pressure equalization valves.

The pressure equalization valve 216 may allow for more efficient oxygen production by equalizing the pressure between the output of the separation bed (e.g., 206 a) near the end of its fill cycle and the separation bed (e.g., 206 b) near the end of its purge cycle. For example, the pressure equalization valve 216 may be activated to equalize the pressure between the output of the separation bed 206a and the separation bed 206b near the end of each purge/fill cycle. The operation of the pressure equalization valve is further described in U.S. patent nos. 4,449,990 and 5,906,672, which are incorporated herein by reference in their entirety. In this manner, each separation bed 206a, 206b is cyclically subjected to alternating fill and purge cycles as controlled by the control system 220 to produce oxygen.

As shown in fig. 2, an optional economizer valve/device 218 may be used to control the delivery of product gas to the user 222. The economizer valve 218 may switch between providing concentrated product gas from the product tanks 208a, 208b or exhausting to room air. For example, the economizer valve 218 may be used to selectively provide various continuous or pulsed flows of oxygen enriched product gas in amounts and times determined by the control system 220. This time is typically based on sensing the inhalation of the user, which is typically determined by sensing a pressure drop or (flow increase) near the nose or mouth of the user.

In this embodiment, the control system 220 may utilize various control schemes to optimize the production and delivery of the concentrated product gas, for example, by controlling the activation, level, and relative timing of the pressure source 203 and valves 204a, 204b, 204c, 204d, 216, and 212. This is accomplished through the use of one or more pressure sensors 224 and/or oxygen concentration sensor(s) 226. In one embodiment, pressure sensor 224 and oxygen sensor 226 monitor the pressure and oxygen concentration entering product tank(s) 208A and 208 (b). In other embodiments, the use of timed loops may be employed, where the loop time is determined or optimized at factory settings or at system start-up using diagnostic procedures. In other embodiments, the cycle time may be determined based on a flow setting and/or a sensed patient flow demand.

While fig. 2 illustrates a Pressure Swing Adsorption (PSA) cycle, other gas concentration cycles may be used, including Vacuum Swing Adsorption (VSA), vacuum-pressure swing adsorption (VPSA), or other similar modes. The particular gas concentration modes are not critical to the embodiments of the invention described herein, so long as they are capable of producing a concentrated gas such as oxygen to a user. Examples of such modes of operation are disclosed, for example, in U.S. Pat. Nos. 9,266,053 and 9,120,050, which are incorporated herein by reference in their entirety.

Referring now to FIG. 3, one embodiment of a sieve bed arrangement 300 is shown. The sieve bed 300 includes a first gas input/output 302, for example, for receiving air and exhausting adsorbed nitrogen. An optional headspace 304 may be provided. The sieve bed 300 also includes springs 306, perforated discs or diffusers 308, and one or more filter media 310. The springs 306 bias the porous disc or diffuser 308 against the screen material 312 (e.g., particulate separation or zeolite material as previously described) to keep the screen material 312 packed together and to resist mechanical movement of the screen material 312 during dynamic pressures used to fill and purge the screen bed 300 during the gas separation process. The other end of the screen material 312 is biased against one or more filter media 314 and a second perforated disk or diffuser 316. The second headspace 318 allows unadsorbed gas (e.g., oxygen) to enter and exit the sieve bed via the input/output port 320. Although this embodiment has been described in particular, one or more components may be omitted, or several components may be integrated. For example, one or more of the head spaces 304 and 318 may be significantly reduced or eliminated. Furthermore, more than one diffuser 308 may be used. For example, two or more diffusers 308 can be used back-to-back, or two or more diffusers 308 can be used with one or more filter media 310 therebetween.

Fig. 5A-5B illustrate another embodiment of a sieve bed 500. The sieve bed 500 includes many of the same functional components, such as those described with respect to the sieve bed 300 of fig. 3. The sieve bed 500 includes a retaining ring or clip 502 for holding an input/output gas cap 504. A spring 506, a retainer 508, a diffuser 510, and filter media 512 and 514 are also provided. Springs 506 bias retainer 508, diffuser 510, and filter media 512 and 514 against particulate screen material 516 to hold screen material 516 stacked together within the screen bed vessel wall to prevent or minimize mechanical movement of the screen bed material during dynamic pressures used in the fill and purge cycles of the separation process. The retaining ring 518 and the second diffuser 524 are located at the other end of the screen material 516 along with one or more filter media 520 and 522. As described with respect to fig. 3, more than one diffuser 510 may be used in any of the embodiments described herein. Fig. 6A-6B illustrate various cross-sectional perspective views of the sieve bed 500 with its components assembled within the sieve bed vessel wall 600.

As noted above with respect to fig. 2, the system draws ambient air through the compressor and moves it through a volume of material in the sieve bed(s) that has a tendency to retain nitrogen, leaving residual oxygen in the output of the system. The sieve material used to adsorb nitrogen is typically in particulate form and must be held within a sieve bed, allowing air to flow in, oxygen to flow out, and periodically flushing the sieve bed to remove the adsorbed nitrogen. The particulate screen material must be held and retained as the gas flows into and out of the screen bed to minimize its relative movement. For example, introducing air under pressure into the sieve bed creates a hammering effect on the sieve material, which can damage the particles and turn them into (reduce) dust, and the escape of dust from the system must be minimized. Excessive loss of screen material is itself a failure mode and as more material is lost, the remaining material moves more freely within the screen bed, accelerating relative movement and degrading to dust.

Semi-permeable membranes or filter media (e.g., 512, 514, 520, and 522) may be used to hold the screen material in place while allowing gas to flow through it. These membranes or filters may have a flexible construction and in this case, mechanical support is required in order to hold the pressurized particulate media against movement and within a confined volume. In order to adequately support the filter media, some of the filtration areas must be blocked from flow by a support mechanical structure such as the prior art disks shown in fig. 4A and 4B. Typically, such structures have holes to allow gas flow while also providing mechanical support through the solid portions of the structure. However, the solid portion does not allow gas flow.

With respect to diffuser structures, there is a limit to the total open area of the sum of the open area of the individual holes and the area of all holes. The area of the individual holes is limited by the mechanical properties of the filter media, which can be caused to sag if the hole geometry (diameter in the circular holes) spans too much. The total open area is also limited by the stress and mechanical properties of the screen material and the ability of the screen bed vessel walls to withstand static and cyclic loads. The geometry of the individual holes and the pattern of the holes also contribute significantly to the energy loss and noise of the system by contributing to the pressure loss of the flowing gas. As will be discussed further herein, proper diffuser geometry may reduce energy loss if appropriate features of hole size, length of the holes in the flow direction, pattern of holes and solid areas, orientation of the holes, and other hole features that affect flow are provided. This may include the use of a plurality of diffusers as described above with respect to fig. 3. In the case of multiple diffusers, each diffuser may have the same or different geometries in order to achieve the desired flow and structural characteristics. Also, there are other losses in the sense of non-uniform flow into or out of the sieve bed during the exhaust cycle, which can be corrected or ameliorated by the influence of flow altering features or geometries of one or more diffusers and/or a sieve cap/interface with flow modifying structure at the face of the sieve bed.

Fig. 7A-7F illustrate various views of various embodiments of a diffuser 510 for a sieve bed. The diffuser 510 has a low solidity, providing a significantly large open area for flow. The diffuser 510 also has structural strength to support the filter media and the force or bias of the transfer springs to keep the screen material from accumulating and to resist mechanical movement within the walls of the screen bed container. The diffuser 510 includes a body 700 having a honeycomb wall structure in one embodiment. Body 700 may have any suitable size and shape, including, for example, the disk shape shown in the figures. In one example, the disk has a diameter of 2.44 inches and a height D2 of 0.5 inches. Other sizes and shapes are also possible for the open area, including, for example, triangular, square, rectangular, other polygonal, circular (see, e.g., body 800 in fig. 8 with circular walls 802 defining circular open area 704), oval, etc.

As shown in the enlarged view of fig. 7B, the walls 706 have a honeycomb (or hexagonal) arrangement of closed open spaces 704. The solidity (ratio of solid to open area) of diffuser 510 may be between greater than or less than 0.10% and 50%. For example, in one embodiment shown in fig. 7A-7D, with a honeycomb cell size D1 equal to 0.125 inches and a wall 706 thickness equal to 0.001 inches and a diffuser body diameter equal to 2.44 inches, a 2.46% solidity is obtained. In another embodiment shown in fig. 7E, a 0.41% solidity is obtained with a honeycomb cell size D1 equal to 0.5 inch and a wall 706 thickness equal to 0.001 inch and a diffuser body diameter equal to 2.44 inches. In yet another embodiment, shown in fig. 7F, with a honeycomb cell size D1 equal to 1.0 inch and a wall 706 thickness equal to 0.001 inch and a diffuser body diameter equal to 2.44 inches, a solidity of 0.17% is obtained. Ideally, while maximizing the open area of the diffuser is highly desirable, an arrangement that improves/increases the open area over the prior art is also desirable and provides efficiency. That is, maximizing the open area is not necessary to achieve efficiency.

By varying the size of the subdivision channels and/or independently varying the length of the channels in the flow direction, the characteristics of the diffuser flow stream (flow stream) may be modified to have the benefit of lower energy loss, more uniform flow into the sieve bed, lower peak velocity at or near the face of the sieve material, lower overall flow velocity in any portion of the sieve bed, lower flow acceleration into the sieve bed, lower flow acceleration out of the sieve bed during the exhaust cycle, lower force on the sieve material, lower peak-to-peak acceleration from dynamic pressure or from bi-directional flow, less impact on the sieve material. The uniform flow or uniform pressure of the flow entering the sieve bed will reduce or eliminate flow within the sieve bed that is not parallel to the general direction of flow through the sieve bed, which increases the distance that air must travel to advance through the sieve material, reducing the time efficiency and oxygen production efficiency of the sieve. Similarly, on exit, uneven restriction of the outlet pressure will cause the flow to converge or diverge and not parallel to the general direction of flow exiting the sieve bed, and thus extend the duration of the exhaust/purge cycle and reduce the efficiency of the exhaust/purge cycle and the overall bi-directional (fill/purge) cycle.

Fig. 9-12 illustrate various embodiments of cross-sectional body profiles of diffuser 510. For example, fig. 9 illustrates a body 900 having a first concave surface profile 902. Fig. 10 illustrates a body 1000 having a first concave surface profile 1002 and a second concave surface profile 1004. Fig. 11 illustrates a body 1100 having a first convex surface profile 1102. Fig. 12 illustrates a body 1200 having a first convex surface profile 1202 and a second convex surface profile 1204. The embodiments of fig. 11 and 12 provide particular advantages of additional structural strength in their central sections due to the higher heights of the diffuser walls and those portions. This resists bending and other undesirable mechanical deformation. Other cross-sectional body profiles are also possible including, for example, wavy or contoured profiles, triangular, saw tooth-shaped, etc. The diffuser body may be made of any suitable material. This includes, for example, metals and plastics. Suitable metals include aluminum and stainless steel. The diffuser body may also be formed via 3D printing techniques that allow for simple and complex space and wall arrangements, including those disclosed herein.

The height of the diffuser body (e.g., D2 in fig. 7C) or the various heights of the body cross-sectional profiles shown in fig. 9-12 reduces flow inefficiency by straightening the flow entering and/or exiting the sieve bed. They also reduce turbulence in the flow through the diffuser wall geometry (e.g., honeycomb, circular, etc.) and through multiple walls or channels. They also direct inward and outward flow in the general direction of the sieve bed to reduce tangential or off-axis flow, which will direct air molecules to travel greater distances to advance into the sieve bed and/or traverse to exit the sieve bed. The height D2 or the height of the cross-sectional profile may be any height determined for improved flow efficiency, including the various heights shown and described with respect to fig. 9-12.

As previously mentioned, the height of the diffuser body (e.g., D2 in fig. 7C) or various heights of the body cross-sectional profile shown in fig. 9-12 also provide structural or retention features. That is, the springs 506 apply a bias or force against the screen material to keep it attached and not moving through the diffuser (see, e.g., fig. 6A-6B). Desirably, the diffuser body is made of a material having sufficient shear, tensile and cyclic fatigue characteristics to provide the required mechanical support (e.g., to prevent sagging under load). Thus, an optimized diffuser body that expands or maximizes the cross-sectional area open for flow while still providing sufficient mechanical strength to hold the screen filter media and screen material is possible given the characteristics of the diffuser body material and minimizing the interstitial volume of the diffuser body material.

In one embodiment, expanding or maximizing the diffuser body open area may be linked to the mechanical properties required for the retention function of the diffuser body. The diffuser body retention function relates to the ability of the diffuser body to adequately support the screen material and filter media in a stacked state. In addition to potentially stronger bulk materials with higher shear, tensile, and cyclic fatigue characteristics, diffusers with a very high percentage of open area for flow compared to the total area available, and thus low solids ratios, can be formed by using optimal pore sizes based on the mechanical requirements of the filter media (e.g., avoiding sagging under mechanical loading), and stacking the largest number of pores by increasing the moment of inertia of the mechanical design in the direction of flow to minimize the interstitial volume of the material.

The use of the diffuser 510 shown in fig. 7A-7D has shown that by reducing the peak velocity of the gas entering the sieve bed (i.e., at or near the face of the sieve material), the separation process can become more efficient while still obtaining conventional gas separation results. Conventional peak speeds up to 168.6 inches/second are reduced to 70.1 inches/second, which is a reduction of about 60%. The reduction in peak velocity of the gas entering the sieve bed translates into a number of practical advantages. For example, less energy is required to operate the gas separation process due to lower peak flow rates. The lower peak flow rate also means that the compressor does not have to work in an effort to reduce component wear and extend compressor life. In addition, the reduced peak velocity reduces pressure or mechanical forces within the screen material and thus reduces dusting and mechanical failure of the screen material by reducing relative movement of the screen bed material. It also reduces dynamic forces on the face of the sieve bed, on the sieve filter(s) and/or on the sieve material, thereby reducing mechanical degradation of the sieve bed material. Still further, the reduced peak velocity reduces noise caused by air flow within the system.

Efficiency is also obtained by having diffuser spaces/channels with height/length (e.g., D2 in fig. 7C) that straighten the flow into and out of the screen material. Straightening the flow also reduces inefficiency by reducing turbulence within the diffuser and/or turbulence caused by the diffuser at the face of the screen material. Straightening the flow also directs the inward and outward flow in the general direction of the bed to reduce tangential or off-axis flow, which will direct air molecules to travel a greater distance forward into the sieve bed or across to exit the sieve bed. The disclosed diffuser arrangement also provides mechanical support for any holding mechanism of the screen material that must be in the flow path. The overall result is a gas separation system with lower energy consumption, greater oxygen output or specific output (oxygen produced per unit energy input), higher reliability defined by sieve bed anti-pulverization life, and lower noise. While all of the benefits and advantages are obtained, any one or more are sufficient to provide an improved gas separation process.

In another embodiment, a system and method are provided having an indicator when a component has been repaired or repaired. In one embodiment, the indicator provides a visual indication if the component has been tampered with in any way. This allows the manufacturer to determine whether the component is being repaired, repaired or tampered with outside the manufacturer's domain. Unauthorized repair or repair can result in premature component wear and failure.

Illustrated in fig. 13 is one embodiment of a system having a tamper resistant feature or arrangement. Fig. 13 shows an enlarged partial cross-sectional view of the top portion of the sieve bed of fig. 6A-6B. The sieve bed includes a tamper-resistant feature or arrangement that provides a visual indication of whether the sieve bed has been opened, for example, to replace sieve material. The screen material 516 is a component that needs to be replaced over time. This is because the screen material 516 degrades over time due to, for example, pulverization or mechanical degradation, moisture, saturated wear, and the like. Typically, the screen material 516 needs to be replaced about every 18 months. Unauthorized replacement of the screen material 516 with a material that is not authorized by the manufacturer can result in premature failure of the pulverized and other gas separation components. The arrangement shown in fig. 13 provides a visual indication of whether the sieve bed has been opened.

Although fig. 13 illustrates an example in which one tamper-resistant cap 504 is associated with a single sieve bed container 600, in other embodiments, a common tamper-resistant cap 504 (acting similarly to a manifold) may be used for a sieve bed container assembly having more than one sieve bed container. In other embodiments, the sieve bed container 600 may use more than one tamper resistant cap 504.

Still referring to fig. 13, tamper resistant cap 504 of the sieve bed includes a body 1300. The body 1300 includes one or more ribs 1302A-D (see also fig. 14A). The ribs include recesses or spaces 1304A-D. The recess along with rim 1308 is arranged to receive and secure a retaining ring or clip 502, which retaining ring or clip 502 is designed to retain cap 504 to sieve bed vessel wall 600. The sieve bed vessel wall 600 also includes an annular recess 1310 for receiving and securing a portion of the retaining ring 502. The ribs 1302A-D also include an outer surface or wall having portions 1316A-D disposed in contact or nearly contact with the container wall 600. In this manner, the retention ring 502 cannot be removed unless one or more of the rib portions 1316A-D are tampered with (e.g., cut, damaged, destroyed, or otherwise modified) to allow the retention clip 502 to be removed. Tampering with the rib portions 1316A-D provides a visual indication through which visual damage the sieve bed may have been opened. Further, tampering with the rib portions 1316A-D may also result in visual damage to the screen container wall 600 in those locations. Further, damage to the rib portions 1316A-D and/or the sieve vessel wall 600 and those locations may result in irreparable damage to the cap 504 and/or the sieve bed vessel wall 600. The end result is to deter tampering or unauthorized repair of the sieve bed, as it may be irreparably damaged.

Fig. 14A-14B illustrate perspective and side elevation views of the embodiment of cap 504 shown in fig. 13. As described above, cap body 1300 includes four ribs 1302A-D, and each rib includes a recess or space (e.g., 1304A-D) for receiving and securing a portion of retaining ring 502. Each rib 1302A-D also includes one or more wall portions or surfaces (e.g., 1316A-D) that are arranged to contact or nearly contact a portion of the sieve bed vessel wall 600 in those locations. Contact with the sieve bed vessel wall 600 in those locations is unnecessary as long as any gap formed is small enough to limit removal of the retaining ring 502. Body 1300 also includes spaced apart rims 516 and 1314 (along with rim 1308) for holding gaskets or O-rings and forming an interference fit that holds cap body 1300 to sieve bed vessel wall 600. The edges 1308, 1312, 1314 are not an essential part of the tamper-resistant feature, but may also be modified to be included.

It should be noted that in other embodiments, cap body 1300 may include less than four ribs 1302A-D, and each rib need not have walls and recesses for securing retaining ring 502. It is sufficient that at least one rib contains these features. Further, the geometry of the ribs, walls, and recesses may be modified from the shapes shown in the embodiments herein, so long as portions are provided in cap body 1300 to secure retaining ring 502 from easy removal (e.g., removal without forming a visual indicator (such as, for example, physical damage or modification to cap body 1300 and/or sieve bed container wall 600). For example, cap body 1300 may include protruding members or tabs 1306 adjacent to recesses 1304B. The protruding tab 1306 may be part of the rib 1302B or independently a separate part thereon. Although one protruding tab 1306 is shown, more than one tab may be provided as part of ribs 1302A-D. In still other embodiments, ribs 1302A-D may be eliminated and instead a plurality of protruding tabs, such as tabs 1306, used in the same location as ribs 1302A-D or in more locations to achieve the same result. In still other embodiments, multiple tabs, such as tab 1306, may be used with one or more ribs. The number, geometry, and shape are not critical, so long as the protruding members (e.g., ribs, tabs, and combinations thereof) at least partially enclose the retaining ring in the manner described herein to prevent tampering and/or provide a tamper indicator.

Fig. 15A-15B illustrate other embodiments of a sifter cap having tamper-resistant features. This includes a ribbed screening cap design. In one embodiment, the sifter cap body may include a swivel dome of various configurations. Fig. 15A illustrates one embodiment of a rib-free sifter cap body 1300. The body includes a cylindrical surface 1500 that turns horizontally (e.g., as opposed to having separate vertically disposed ribs) protruding or extending from the body 1300 and is arranged with an edge portion 1504 that contacts or is in close proximity to contact the screen container wall 600 to secure the retaining ring or clip 502 in a manner similar to the wall portions 1316A-D of fig. 13-14B. Fig. 15B shows another embodiment of a rib-free sifter cap body 1300 having fewer or smaller cylindrical surfaces 1502 than the embodiment of fig. 15A. Cylindrical surface 1502 is also arranged with edge regions 1504 to contact or nearly contact screen container wall 600 to secure retaining ring or clip 502 in a manner similar to wall portions 1316A-D of fig. 13-14B. The remaining features of the sifter cap body are similar to those already described in fig. 13-14B. Thus, the non-ribbed walls/surfaces 1500 and 1502 secure the retaining ring/clip 502 in the same manner as the wall portions 1316A-D, but along a larger perimeter than by using the ribs 1302A-D alone. Attempts to remove the retaining ring or clip 502 from the embodiment of fig. 15A and 15B will result in damage to the edge or perimeter portion 1504 that secures the retaining ring or clip 502 to provide a tamper indication. Thus, the sifter cap bodies disclosed herein are not limited to ribbed tamper resistant features and include both ribbed and/or non-ribbed arrangements.

Fig. 16A-16D illustrate another embodiment of a sifter-bed cap 504 having tamper-resistant features. In this embodiment, cap 504 includes one or more structural portions that break or fracture when an attempt is made to remove retaining ring or clip 502, such that cap 504 is no longer reusable. This is achieved by forming one or more weakened portions in the body 1300.

In the illustrated embodiment, the body 1300 includes a dome portion 1600, the dome portion 1600 being arranged to partially or fully fracture when an attempt is made to remove the retaining ring or clip 502. Partial or complete fracture or rupture, among other things, destroys the ability of the interior space 1604 to function properly at the desired operating sieve bed pressure, which effectively disables the gas separation system. Referring to fig. 16C and 16D, the body 1300 includes recesses or spaces 1304A-D for at least partially securing the retaining ring or clip 502. Recesses or spaces 1304A-D are defined on one side by perimeter wall 1602 of body 1300. As shown in fig. 16C, the wall 1602 has a first wall thickness where the wall 1602 defines a recess or space 1304A-D. Where peripheral wall 1602 does not define recesses or spaces 1304A-D, wall 1602 has a second thickness less than the first thickness shown in FIG. 16C, as shown in FIG. 16D. The difference in thickness may be any difference that makes the wall 1602 more susceptible to cracking or breaking when attempting to remove the retention ring or clip 502. In one embodiment, the thickness difference may be greater or less than 25% to 90%. The precise thickness differential is not critical as long as the portion(s) of the sieve bed cap are broken or fractured when attempting to remove the retaining ring or clip 502.

In another embodiment, the lower dome perimeter wall 1606 adjacent to wall 1602 may have portions of different thickness in the same manner as described for wall 1602 to achieve the same fracture or fracture result. That is, the portion of wall 1606 shown in fig. 16C may have a first thickness that is greater than the portion of wall 1606 shown in fig. 16D. In this way, the smaller thickness of the portion of wall 1606 shown in fig. 16D is arranged to fracture or break when an attempt is made to remove the retaining ring or clip 502. Other arrangements of caps 504 having portions arranged to break, fracture or fracture may also be used to prevent unauthorized access to the sieve bed and/or reuse of tampered sieve beds and caps.

In one embodiment, cap 504 may be made of polycarbonate or other plastic and/or thermoplastic. The material composition may be any composition that allows the structural portion to fracture or break when an attempt is made to remove the retaining ring or clip 502 so that the cap 504 is no longer reusable. This may also include metals, alloys, ceramics, and other moldable, printable, and/or machinable materials.

Another factor that can promote sieve bed wear and tear, including pulverization and fluidization of the sieve bed material, is the non-uniform flow distribution and velocity of the gas (e.g., air) entering the sieve bed material. Air is typically input into the sieve bed via a cap or other input interface. The internal chamber geometry of the cap/interface may result in uneven flow distribution and/or high flow velocity concentration regions of the gas entering the sieve bed material. These undesirable effects may be addressed by using flow modifying structures, baffles, and/or protrusions to obtain a more uniform and/or optimized flow distribution and flow velocity of the gas entering the sieve bed material. Various embodiments of sieve bed caps/interfaces for modifying the flow distribution and/or flow velocity of gas entering the sieve bed material are shown in fig. 17A-27B.

Referring now to fig. 14A, 14B, and 17A-17B, one embodiment of a sifter-cap/interface 504 having flow-modifying structures, baffles, and/or protrusions is shown. Referring now to the bottom view of fig. 17A, the body 1300 includes an inner chamber geometry having a hemispherical or dome-shaped wall or surface 1700 and first, second, and third flow modifying structures 1702 and 1704, 1706 and 1708, 1710. A first gap 1712 is located between the first flow modifying structures 1702 and 1704. A second gap 1714 is located between the second flow modifying structures 1706 and 1708. In this embodiment, the flow modifying structures are arranged in generally three rows spaced apart relative to the gas ports 1716, the gas ports 1716 feeding gas into the chamber. The first flow modifying structures 1702 and 1704 are juxtaposed proximate the gas port 1716 a first distance D1, which may be about 0.45 inches (shown exaggerated to scale in fig. 17A). The second flow modifying structures 1706 and 1708 are spaced apart from the first flow modifying structures 1702 and 1704 by a distance D2, which may be about 0.42 inches. Third flow modifying structure 1710 is spaced apart from second flow modifying structures 1706 and 1708 by a distance D3, which may be about 0.33 inches. In other embodiments, these distances may be changed without substantially changing the flow modification results.

In one embodiment, the flow modifying structures 1702-1710 are baffles or ribs that deflect gas introduced from the ports 1716. As shown in fig. 17A, the first flow modifying structures 1702 and 1704 and the third flow modifying structure 1710 have a substantially planar body with rounded or curved end surfaces. The second flow modifying structures 1706 and 1708 have curved bodies with curved end faces. In this embodiment, the curved bodies of structures 1706 and 1708 are shown as being curved in a general direction toward gas port 1716. In other embodiments, the amount of flatness and curvature of any of these structures may be different than shown without significantly affecting the flow modification results.

Referring now to fig. 17B, the cross-sectional view of fig. 17A is shown to a relative scale. Each of the bodies of the flow modifying structures 1702-1710 extends a distance down from the wall 1700 and into the chamber. The inner chamber has a height H3 as shown, which may be about 1.2 inches. The first flow modifying structures 1702 and 1704 extend downwardly to a height H1 as shown, which may be about 0.91 inches. The second flow modifying structures 1706, 1708 and third flow modifying structure 1710 extend downwardly to a height H2 as shown, which may be about 0.71 inches. In other embodiments, these dimensions may be changed without significantly affecting the flow modification results. Fig. 17C is a bottom perspective view further illustrating the size, location, and shape of the flow modifying structures 1702-1710 and the gaps 1712 and 1714. Fig. 17D is a cross-sectional perspective view of the sieve bed cap, and fig. 17E is an associated cross-sectional view of fig. 17D showing first flow modifying structures 1702 and 1704 and gap 1712. Fig. 17F is another cross-sectional perspective view and fig. 17G is an associated cross-sectional view of fig. 17F showing second flow modifying structures 1706 and 1708 and gap 1714. And, fig. 17H is another cross-sectional perspective view, and fig. 17I is an associated cross-sectional view of fig. 17H illustrating a third flow modifying structure 1710.

Referring back now to FIG. 17A, gas is fed into the chamber from port 1716 and encounters first flow modifying structures 1702 and 1704 and gap 1712. This provides a first flow modification to the gas, with one portion passing through gap 1712 and into space 1718 and the other portion being deflected to spaces 1720 and 1722 where they encounter dome surface 1700. The flow of gas then encounters the second flow modifying structures 1706 and 1708 and the gap 1714, with a smaller portion of the gas passing through the gap 1714 and the other portion being directed to the spaces 1720 and 1722 and encountering the dome surface 1700. In the illustrated embodiment, the gap 1714 is smaller than the gap 1712, allowing less gas to pass therethrough than the gap 1712. In other embodiments, the gap 1714 may be about 0.1 to 1.0 times the size of the gap 1712. In other embodiments, the gap 1712 may be correspondingly smaller than the gap 1714. The second flow modifying structures 1706 and 1708, by virtue of their shape, deflect a portion of the gas inwardly into the gap 1714 and deflect a portion of the gas outwardly toward the spaces 1720 and 1722. This provides additional or second flow modification to the gas flow. The gas flow then encounters the third flow modification structure 1710. This causes the gas to deflect into spaces 1726 and 1728 where it encounters dome surface 1700. Fig. 18B, discussed below, illustrates these flow patterns through computational fluid dynamics simulations.

Thus, the gas flow may be incrementally modified by each row of structures or baffles in order to obtain a desired flow distribution and/or velocity of the gas entering the sieve bed material. This provides for optimization of flow to achieve a more uniform distribution and flow velocity as the gas enters the screen material, thereby reducing wear and tear (e.g., dusting, fluidization, etc.) of the screen material.

Fig. 18A-18C illustrate flow distribution and velocity produced by the structure, baffles, and/or protrusions of the cap/interface of fig. 17A-17I, as modeled by computational fluid dynamics software of Ansys, inc. Fig. 18A shows a cross-sectional view similar to fig. 17B, with the resulting calculated flow streams 1800 and their velocities directed within the cap/interface shown along the x-axis direction and the y-axis direction. Fig. 18B shows a bottom view similar to fig. 17A, and wherein the resulting calculated flow streams 1800 and their velocities are shown along the x-axis and z-axis directions. In fig. 18A and 18B, for flow stream 1800, the speed is indicated as higher to lower as the shade changes from light to dark.

Fig. 18C illustrates the resulting calculated flow and/or velocity distribution at the planar location indicated in fig. 18A, which is proximate to the face of the sieve bed material and/or diffuser (e.g., 510). Thus, fig. 18C shows calculated flow distribution and velocity at or near the face of the sieve bed material. As shown, the flow distribution includes a relatively large substantially uniform distribution of flow areas 1802 extending from the center and outwardly. There is also a second smaller region 1804 having an arcuate shape with a substantially uniform flow distribution. Similar to fig. 18A and 18B, as the shade changes from light to dark, the speed is indicated as being higher to lower. Two exceptions are small areas 1806 and 1808 where these dark areas represent higher than average flow velocity. In addition to the very small regions 1806 and 1808, an optimized and substantially uniform gas flow distribution of about 70-80% (or more) is obtained representing the region near the face of the sieve bed material. By introducing the gas into the sieve bed material more evenly, pockets of the sieve bed material that may not otherwise be reached by the gas as it is unevenly distributed as it enters the sieve bed material are limited or eliminated, which uniformity thereby makes the sieve bed more efficient.

For reference, fig. 18D and 18E illustrate the flow distribution and velocity of the cap/interface of fig. 17A-17I, but without any flow modifying structures, baffles, and/or protrusions. As seen in fig. 18D, the flow stream 1800 is unevenly distributed within the interior chamber of the cap. Also, as seen in fig. 18E, the resulting flow distribution is concentrated along a narrow arc 1810 along the inner chamber boundary wall opposite the gas ports 1716. Such uneven flow distribution creates undesirably high flow rates and/or required pressures that promote sieve bed wear and tear, including pulverization and fluidization of the sieve material, wear of the filter media, compressor wear (over time), and the like.

Fig. 19A and 19B illustrate another embodiment of a sieve bed cap/interface 504 with a flow modification structure. The embodiment of fig. 19A and 19B is similar to the embodiment of fig. 17A-17I, except that the second flow modifying structures 1900 and 1902 are not curved (relative to the second flow modifying structures 1706 and 1708 of fig. 17A-17I, which are shown as curved). As shown, the second flow modifying structures 1900 and 1902 have substantially planar bodies with rounded or curved end surfaces. Apart from this difference, the embodiments of fig. 17A-17I and 19A-19B are similar (including flow patterns; see fig. 20B), and the corresponding descriptions are incorporated herein by reference.

Fig. 20A-20C illustrate flow distribution and velocity produced by the structure, baffles, and/or protrusions of the cap/interface of fig. 19A-19B, as modeled by computational fluid dynamics software of Ansys, inc. Thus, the same analysis as shown and described in fig. 18A to 18C is performed on the embodiment of fig. 19A to 19B. Fig. 20A shows a cross-sectional view similar to fig. 19B, and wherein the resulting calculated flow streams 2000 and their velocities directed within the cap/interface are shown along the x-axis direction and the y-axis direction. Fig. 20B shows a bottom view similar to fig. 19A, and wherein the resulting calculated flow streams 1800 and their velocities are shown along the x-axis and z-axis directions. In fig. 20A and 20B, for the flow stream 2000, the speed is indicated as higher to lower as the shade changes from light to dark.

FIG. 20C illustrates the resulting calculated flow and/or velocity distribution at the planar location indicated in FIG. 20A, which is proximate to the face of the sieve bed material and/or diffuser (e.g., 510). Thus, fig. 20C shows calculated flow distribution and velocity near the face of the sieve bed material. As shown, the flow distribution includes a relatively large substantially uniform distribution of flow areas 2002 extending centrally and outwardly. There is also a second smaller region 2004 having a slightly interrupted arcuate shape with a substantially uniform flow distribution. Similar to fig. 20A and 20B, the speed is indicated as higher to lower as the shade changes from light to dark. Two exceptions are small areas 2006 and 2008, where these dark areas represent higher than average flow velocity. An optimized and substantially uniform gas flow distribution of about 70-80% (or more) representing the area near the face of the sieve bed material is obtained, except for the very small areas 2006 and 2008. As previously described, this uniformity makes the sieve bed more efficient by more uniformly introducing gas into the sieve bed material, thereby limiting or eliminating pockets of the sieve bed material that may not otherwise be reached by the gas as it is unevenly distributed as it enters the sieve bed material.

In addition to being more uniform in distribution (which contributes to sieve bed efficiency), the flow rates according to these embodiments are substantially lower than otherwise provided. Lower flow rates reduce pulverization, fluidization and other abrasion and tear on the sieve bed and sieve bed material. This extends the life of the sieve bed and thus the life of the gas concentration system.

Fig. 21A-21D illustrate another embodiment of a sieve bed cap/interface 504 with a flow modification structure. This embodiment includes two rows of flow modification structures. The first row is identical to the embodiment of fig. 17A-17I and includes first flow modifying structures 1702 and 1704 and a gap 1712. The second flow modification structure is different. These include flow modifying structures 2100 and 2102 and gaps 2104 that form a V-shape with curved legs (e.g., 2100 and 2102) and small gaps (e.g., 2104) at the apexes of the V-shape. As previously described, the flow modifying structures 1702 and 1704 and the gap 1712 provide a first gas flow modification. Gas passing through gap 1712 enters space 2106 and encounters second flow modification structures 2100 and 2102 and gap 2104. Part of the gas passes through gap 2104 and another part is deflected by structures 2100 and 2102 into spaces 2108 and 2110 where they encounter dome surface 1700. Gas passing through the gap 2104 enters the space 2112 where it encounters the dome surface 1700. In the illustrated embodiment, gap 2104 is smaller than gap 1712, allowing less gas to pass therethrough than gap 1712. In other embodiments, the gap 2104 may be about 0.1 to 1.0 times the size of the gap 1712. In other embodiments, gap 1712 may be correspondingly smaller than gap 2104. Thus, the second flow modifying structures 2100 and 2102 and the gap 2104 provide a second flow modification.

Fig. 22A-22D illustrate another embodiment of a sieve bed cap/interface 504 with a flow modification structure. This embodiment includes a flow modifying structure 2200 having a V-shaped portion with stepped or contoured legs 2204 and 2206. Gas entering the interior chamber encounters the V-shaped portion and is separated and deflected into spaces 2208 and 2210. However, because legs 2204 and 2206 of the V-shaped portion have stepped or contoured surfaces as shown, a small portion of the gas flow is deflected back against the oncoming flow. The net result is that a portion of the gas flow is not deflected into spaces 2208 and 2210, which helps to more evenly distribute the flow because not all of the flow is deflected into side spaces 2208 and 2210. The portion of the flow deflected into spaces 2208 and 2210 also flows into space 2212 via dome surface 1700 and cylindrical portion 2202 of flow modifying structure 2200.

Fig. 23A-23D illustrate another embodiment of a sieve bed cap/interface 504 with a flow modification structure. This embodiment includes a flow modifying structure 2300, the flow modifying structure 2300 being cylindrical in nature and including a cylindrical first portion 2302 and a tapered or conical second portion 2304. The first portion 2302 provides a first gas flow modification by deflecting the gas enclosure structure 2300 into a space proximate to the dome surface 1700. By virtue of its tapered or conical geometry, the second portion 2304 provides a second flow modification by deflecting the gas flow direction down to the sieve bed material. In other embodiments, the second portion 2304 may be more tapered or less tapered or more conical or less conical than the illustrated portion.

Fig. 24A-24D illustrate another embodiment of a sieve bed cap/interface 504 with a flow modification structure. This embodiment includes a flow modifying structure 2400 that is cylindrical in nature and includes a first portion 2402 that is generally cylindrical and a second portion 2404 that is sloped, the second portion 2404 may be curved (including concave and/or convex as shown). The first portion 2402 provides a first gas flow modification by deflecting the gas around the structure 2400 into a space proximate the dome surface 1700. By virtue of its inclination, the second portion 2404 provides a second flow modification by deflecting the gas flow downward to the sieve bed material at a region proximate to the gas inlet port 1716. In other embodiments, second portion 2404 may be more or less sloped than the portion shown.

Fig. 25A-25D illustrate another embodiment of a sieve bed cap/interface 504 with a flow modification structure. This embodiment includes a flow modifying structure 2500 located very near the gas entry port 1716. The reason for such close proximity to the gas entry ports 1716 is to deflect the incoming gas flow stream into at least two smaller gas flow streams, thereby allowing the dome surface 1700 to distribute the streams more evenly than when only a single gas stream encounters the dome surface 1700. The flow modifying structure 2500 includes a substantially planar surface 2504 having curved end surfaces 2502 and 2506, respectively, on sides thereof. Curved end surfaces 2502 and 2506 provide less turbulence and less noise deflection of the gas flow to dome surface 1700. In other embodiments, end surfaces 2502 and 2506 need not be curved, but may be substantially planar and angled relative to surface 2504. As shown in fig. 25D, the flow modification structure 2500 may extend significantly downward into the interior chamber of the sieve bed cap/interface. In other embodiments, it may extend less than the length shown, including, for example, only up to or just beyond the perimeter of the gas entry port 1716.

Fig. 26A-26D illustrate another embodiment of a sifter-cap/interface 504, the sifter-cap/interface 504 having a cylindrical wall 2600 instead of, for example, a dome surface 1700. In this embodiment, the side and top portions of the cylindrical wall 2600 act as flow modifying structures and distribute the flow into two regions. The gas flow entering from port 1716 encounters sidewall portion 2602, which sidewall portion 2602 splits the flow into an up-flow and a down-flow. The upper flow stream is then deflected back downwardly by the top surface 2604 and the side surface portions 2606, forming a second lower flow stream. Dividing the primary gas flow stream entering from the gas inlet ports 1716 into two or more flow streams provides a more uniform flow distribution of the gas entering the sieve bed material. Surfaces 2608, 2610, 2612, and 2614 optionally extend the lower portion of body 1300 in a stepwise manner to provide an attachment base to the sieve bed container wall 600 (see fig. 6).

Fig. 26E-26F illustrate the flow distribution and velocity produced by the cap/interface of fig. 26A-26D, as modeled by computational fluid dynamics software of Ansys, inc. Thus, the same analysis as shown and described in fig. 18A to 18C is performed on the embodiment of fig. 26A to 26D. Fig. 26D shows a cross-sectional view similar to fig. 19B, and wherein the resulting calculated flow streams 2614 and their velocities directed within the cap/interface are shown along the x-axis direction and the y-axis direction. In fig. 26D, for the flow stream 2000, the speed is indicated as higher to lower as the shade changes from light to dark.

Fig. 26F illustrates the resulting calculated flow and/or velocity distribution at the planar location indicated in fig. 26E, which is proximate to the face of the sieve bed material and/or diffuser (e.g., 510). Thus, fig. 26E shows the flow distribution and velocity calculated at the face of the sieve bed material. As shown, the flow distribution includes a substantially uniform distribution of the flow region 2616. There is also a second region 2618 with a uniform flow distribution. Similar to fig. 26E, the speed is indicated as higher to lower as the shade changes from light to dark. Two exceptions are small areas 2622 and 2624 where these dark areas represent higher than average flow velocity. An optimized and substantially uniform gas flow distribution of about 70-80% (or more) is obtained representing the area near the face of the sieve bed material, except for the very small areas 2622 and 2624. As previously described, this uniformity makes the sieve bed more efficient by more uniformly introducing gas into the sieve bed material, thereby limiting or eliminating pockets of the sieve bed material that may not otherwise be reached by the gas as it is unevenly distributed as it enters the sieve bed material.

Fig. 27A and 27B illustrate another embodiment of a sieve bed cap/interface 504, the sieve bed cap/interface 504 having a continuous flow modification structure 2700 rather than a structure such as discrete rows or columns. The structure 2700 includes several sections including curved side sections 2712 and 2714 and a center section 2706. Curved side portions 2712 and 2714 and central portion 2706 extend from dome surface 1700 and enter the interior chamber of the cap via curved surfaces 2702, 2704 and 2708 and surface 2710. The surface 2710 may be linear or curved (as shown by 2716) (including having multiple curves) and the first flow modification is performed by dividing the gas flow introduced from port 1716 into at least two flow streams. Curved side portions 2712 and 2714 function similarly to curved flow modification structures 1706 and 1708 (e.g., fig. 17A) by providing a second flow modification that directs a portion of the gas flow back toward spaces 2718 and 2720 where the gas flow encounters dome surface 1700 and is directed downward toward the screen material. This redirection provides a greater distribution of flow from the region (e.g., spaces 2718 and 2720) into the sieve bed than would otherwise be provided, resulting in a more uniform overall flow distribution of gas into the sieve material. While this embodiment shows a single central portion 2706 extending into the interior chamber of the cap, in other embodiments, the central portion 2706 may be divided into several portions mimicking the low modification structures of fig. 17A-21D, for example, whereby the structures may extend from the dome surface 1700 through the curved surface and be connected to each other through the curved surface while still maintaining the same general configuration as shown in these embodiments.

The end result of the foregoing embodiments is a more uniform flow distribution and lower flow velocity than sieve bed cap 504 without any flow modification structures associated therewith. In addition, the flow modifying structures of the various embodiments shown and described herein may be further combined to form additional combinations of flow modifying structures. Further, the illustrated and described embodiments of the sieve bed cap/interface may be used with or without a flow diffuser such as diffuser 510 disclosed herein. Still further, while the flow modifying structure has been shown by way of example as part of a sieve bed cap/interface, these same structures may also be implemented as separate components, inserts, and/or adapters for placement within an existing sieve bed cap/interface or for separate mounting within a sieve bed assembly for operation in conjunction with a sieve bed cap or interface. Still further, the sieve bed cap/interface may include both tamper resistant features and flow modifying structures as disclosed herein.

While the present invention has been illustrated by a description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the disclosure to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, the relative sizes, dimensions, and shapes of the components may be varied without significantly affecting their function. The invention in its broader aspects is therefore not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.

Claims (20)

1. A tamper resistant cap for a sieve bed, comprising:

a body comprising at least one protruding member and an adjacent recess for at least partially holding a retaining ring; and

wherein the at least one protruding member extends towards the sieve bed vessel wall so as to at least partially enclose the retaining ring between the vessel wall and the body.

2. The cap of claim 1, wherein the protruding member comprises at least one rib.

3. The cap of claim 1, wherein the protruding member comprises a plurality of ribs.

4. The cap of claim 1, wherein the cap body comprises a swivel dome having the at least one protruding member.

5. The cap of claim 1, wherein the cap body comprises a plurality of protruding members and a plurality of adjacent recesses.

6. The cap of claim 1, wherein the body includes a ledge adjacent the recess.

7. The cap of claim 1, wherein the protruding member comprises a tab.

8. The cap of claim 1, wherein the protruding member comprises a plurality of tabs.

9. The cap of claim 1, wherein the protruding member comprises a plurality of ribs and tabs.

10. The cap of claim 1, wherein the protruding member comprises a plurality of tabs and ribs.

11. A sieve bed, comprising:

a vessel for containing a separation medium and having a vessel wall;

a retaining ring disposed at least partially in the container wall;

a cap having a body including at least one protruding member and an adjacent recess for at least partially retaining the retaining ring; and

wherein the at least one protruding member extends towards the container wall so as to at least partially enclose the retaining ring between the container wall and the cap body.

12. The sieve bed of claim 11, wherein the protruding member comprises at least one rib.

13. The sieve bed of claim 11, wherein the protruding member comprises a plurality of ribs.

14. The sieve bed of claim 11, wherein the cap body comprises a swivel dome having the at least one protruding member.

15. The sieve bed of claim 11, wherein the cap body comprises a plurality of protruding members and a plurality of adjacent recesses.

16. The sieve bed of claim 11, wherein the body comprises a ledge adjacent the recess.

17. The sieve bed of claim 11, wherein the protruding member comprises a tab.

18. The sieve bed of claim 11, wherein the protruding member comprises a plurality of tabs.

19. The sieve bed of claim 11, wherein the protruding member comprises a plurality of ribs and tabs.

20. An oxygen concentrator comprising:

a pressure source;

at least one sieve bed having:

a vessel for containing a separation medium and having a vessel wall;

a retaining ring disposed at least partially in the container wall;

a cap having a body including at least one protruding member and an adjacent recess for at least partially retaining the retaining ring; and

wherein the at least one protruding member extends towards the container wall so as to at least partially enclose the retaining ring between the container wall and the cap body;

a plurality of valves; and

a patient output.