Open hole check valve

Abstract

The invention relates to a check valve (1) comprising: a valve housing (10); a valve member (11) within the housing, the valve member being movable between an open position and a closed position; and at least one restricted passage (14) through the valve member wherein, in the closed position, the at least one restricted passage is arranged to allow restricted backflow of fluid through the valve. The invention also relates to a system comprising an electrochemical device and a check valve, where the check valve is connected to an outlet conduit of the electrochemical device.

Description

Technical Field

[0001] The present invention relates to a check valve with a restricted passage for equalizing the pressure difference on both sides of the valve. The valve is suitable for use with, but not limited to, an electrolyzer. Background Art

[0002] The flow of fluids in pipes is common in many industries. There are many known ways to control the flow of fluids, including a variety of valves. When it is necessary to direct the flow of fluids in a pipe, a check valve is used. Check valves can be selected from a variety of types, such as swing, lift, butterfly, stop or tilting disc.

[0003] In some cases, it may not be desirable to completely stop the flow of a fluid, so an orifice plate can be used to restrict the flow of fluid in a pipe. The problem here is that when an orifice plate is used, the flow rate is permanently restricted to within parameters based on the hole size. This is not ideal in many applications, where higher flow rates are required under normal operation or for specific flow rates.

[0004] Additionally, a traditional check valve that completely blocks one-way flow may not be desirable in some situations because it may result in problematic pressure differentials on either side of the check valve.

[0005] An object of the present invention is to provide an improved check valve which allows the pressure differential across the check valve to be equalized and which allows variable fluid flow rates to be achieved in different directions. Summary of the invention

[0006] According to one aspect of the present invention, a check valve is provided, comprising: a valve housing; a valve member located in the housing, the valve member being movable between an open position and a closed position; and at least one restricted channel passing through the valve member, wherein in the closed position, the at least one restricted channel is arranged to allow restricted backflow of fluid through the valve.

[0007] This valve is particularly advantageous for use with electrochemical devices such as electrolyzers. Such devices have a bleed line that opens to allow discharge of product produced during startup and shutdown of the device and closes under normal operating conditions. However, standard check valves are not suitable for regulating fluid flow along the bleed line because, when closed, they will completely prevent backflow up the bleed line into the device. This complete prevention of backflow can be problematic if a pressure drop occurs inside the device, such as occurs during idling of the device, thus damaging the device; therefore, it is desirable to allow a restricted return flow of air through the bleed line to prevent a pressure drop within the device, but to limit the return flow of gas / air to a level low enough that it is not dangerous to the electrochemical device. The valve also protects the device from sudden external pressure surges by allowing the restricted fluid to flow through the restricted passage, gradually equalizing the pressure differential across the valve.

[0008] Preferably, the non-return valve further comprises at least one further passage arranged to allow fluid to flow through or around the valve member when the valve member is in the open position.

[0009] Preferably, the at least one further passage is at least one bypass passage in the housing arranged to provide a fluid flow path around the valve member.

[0010] Alternatively, the at least one further passage is at least one through-flow passage through the valve member, the through-flow passage being arranged to provide a fluid flow path through the valve member.

[0011] Preferably, the at least one further channel has a larger cross-sectional area than the at least one restricted channel.

[0012] Preferably, the valve member is arranged to extend through the interior of the housing.

[0013] Preferably, the valve member comprises sealing means for sealing the valve member to a portion of the housing in the closed position.

[0014] Preferably, the sealing means is a gasket, more preferably an O-ring gasket.

[0015] Preferably, sealing means are arranged on the valve member to surround an inlet or outlet of at least one restricted passage.

[0016] Preferably, the sealing means is arranged to prevent fluid flow from the inlet of the valve housing through or around the valve member when the valve member is in the closed position.

[0017] Preferably, the at least one restricted passage is arranged in the centre of the valve member.

[0018] Preferably, the non-return valve comprises biasing means within the housing, the biasing means being arranged to bias the valve member towards the closed position.

[0019] Preferably, the biasing means comprises at least one of: a spring, preferably a helical spring; a biasing hinge; a poppet valve; and / or a compressible polymer.

[0020] Preferably, the biasing means is calibrated such that the valve member is arranged to move from the open position to the closed position at a pressure below 0.5 bar.

[0021] Preferably, the diameter of the at least one restricted channel is between 1 and 100 microns, preferably between 1 and 50 microns, more preferably between 1 and 20 microns, even more preferably between 5 and 15 microns.

[0022] Preferably, the check valve is one of: a swing check valve; a lift check valve; a butterfly check valve; a stop check valve; or a tilting disc check valve.

[0023] Preferably, the valve member is formed from stainless steel.

[0024] According to another aspect of the present invention, a system is provided, comprising: an electrochemical device; and a check valve according to any one of the above descriptions, wherein the check valve is connected to an outlet pipe of the electrochemical device.

[0025] Preferably, the electrochemical device is an electrolyser.

[0026] Preferably, the outlet line is the discharge line of the electrolysis cell.

[0027] Preferably, the check valve further comprises at least one further passage arranged to allow fluid to flow through or around the valve member when the valve member is in the open position, and the total cross-sectional area of ​​the at least one further passage is greater than or equal to the cross-sectional area of ​​the outlet conduit.

[0028] As used herein, the terms "orifice check valve," "balanced check valve," and "balanced check valve" may be used interchangeably. The restricted passage through the valve member is also referred to herein as an "orifice."

[0029] The check valve herein may be based on any suitable check valve type, such as but not necessarily limited to a swing, lift, butterfly, stop or tilting disc valve.

[0030] In a preferred embodiment, the size of the valve housing is substantially similar to the diameter of the pipeline in which the orifice check valve is placed. Like this, the forward flow of fluid is not restricted by the valve, which allows the fluid to flow through at the same rate as flowing through the pipeline.

[0031] It is contemplated that when in the open position, the valve can accommodate substantially the same flow as the conduit in which the open-hole check valve is placed.

[0032] It is envisaged that in the closed (ie seated) position, the valve member spans the entire flow path of the housing.

[0033] It is envisaged that various means may be used to allow movement of the valve member. This may include a spring with a piston, a hinge at one end of the movable member, a poppet valve, a compressible polymer.

[0034] Although it is envisioned that the valve may be calibrated to open / close at a wide range of pressures, in a preferred embodiment of the invention, the valve is calibrated to open at low pressures, for example below 0.5 bar, more preferably below 0.1 bar, and most preferably below 0.05 bar. The above values ​​apply to systems designed to operate at substantially 35 bar. Alternatively, the ratio of operating pressure to start-up pressure may be any one of 10:1, 50:1, 100:1, 250:1, 500:1, 700:1, 750:1 or 100:1 or between any two thereof.

[0035] In a preferred embodiment, the valve member is a piston or equivalent having sealing means, optionally provided with O-rings, gaskets or other sealing means, to ensure a fluid tight connection between the valve member and the valve housing so that the calibrated restricted passage is the only viable fluid path.

[0036] The size of the restricted passage is preferably calibrated to limit the backflow rate to a level that is safe for the device using the valve. In a preferred embodiment, the restricted passage in the valve member is a micrometer-sized hole. Preferably, it is below 100 microns, more preferably below 50 microns, and even more preferably below 20 microns. It is expected that the micrometer-sized hole will be between 5 and 15 microns. The restricted passage can be located anywhere on the valve member, including the edge, but in a preferred embodiment, the hole is located inside the valve member, and more preferably still substantially in the center of the valve member. Selecting this position allows for proper sealing at the boundary.

[0037] In a preferred embodiment of the invention, there is one restricted channel. In another embodiment, there are two or more restricted channels, and the total cross-sectional area of ​​these channels is calibrated according to the invention. If there are multiple channels, it is expected that the distribution will be substantially uniform, such as two channels equidistant from the center and circumference of the valve member, or three channels arranged in an equilateral triangle, four channels arranged in a square, and so on.

[0038] The valve member may be made of stainless steel or any suitable material.

[0039] It is contemplated that the present invention may be used in conjunction with any device or system. In a preferred embodiment, the present invention is used with an electrolyser, more preferably an AEM electrolyser. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] To aid understanding of the present invention, specific embodiments thereof will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 An open-bore check valve is shown in a closed position; Figure 2 An open-hole check valve is shown in an open position; Figure 3 An open-orifice check valve is shown in an open position with fluid flowing; Figure 4 An open-orifice check valve is shown in a closed position in a reverse flow condition; and Figure 5 The open-orifice check valve is shown in the closed position, allowing pressure equalization. DETAILED DESCRIPTION

[0041] Reference Figure 1, the orifice check valve 1 and the housing 10 can be seen. The housing 10 surrounds an inner cavity in the valve. The inner side wall 2 of the valve housing is shown in dashed lines, and the outer side wall 3 of the valve housing is shown in solid lines. The valve housing 10 also includes two end walls, a first end wall 4 located at a first end of the valve (in normal operation, it is the upstream end of the valve) and a second end wall 5 located at the other end of the valve (in normal operation, it is the downstream end of the valve). The cavity is surrounded by the inner side wall 2 and the end walls 4, 5 of the housing.

[0042] The valve 1 comprises a first opening 15a in the first end wall 4 and a second opening 15b in the second end wall 5 for fluid to flow into or out of the valve cavity. In this example, a conduit extends from each opening 15a, 15b for guiding fluid to flow into or out of the cavity through the opening. In normal operation, the first opening 15a serves as an inlet for fluid to enter the valve cavity and the second opening 15b serves as an outlet for fluid to leave the valve cavity.

[0043] The valve 1 also includes a valve member 11 extending between the inner side walls 2 of the valve housing 10, so that the valve member 11 substantially spans the entire width of the inner cavity of the valve housing. The valve member 11 can move in the cavity under the force of a biasing device or against the force of a biasing device, in this example, the biasing device is a coil spring 12 located in the valve cavity. In this example, the valve member 11 is circular and the inner wall 2 of the valve housing 10 is cylindrical. The valve member 11 can move through the valve cavity along the longitudinal axis of the valve, that is, along the axis from the first opening 15a to the second opening 15b. Therefore, the valve member can be regarded as a piston, and the cavity in the valve housing can be regarded as a cylinder guiding the piston.

[0044] The valve member 11 is movable between a closed position and an open position. Figure 1 In the example shown, the valve member 11 is in the closed position under the force of the spring 12. The valve member comprises a sealing device, which in this example is an O-ring gasket 13. When the valve member 11 is in the closed position, the O-ring gasket 13 is pressed against the first end wall 4 under the force of the spring 12. The gasket ensures a tight seal against the first end wall 4. The diameter of the O-ring gasket is at least as large as the diameter of the first opening 15a, so that the gasket can seal around the opening 15a.

[0045] The valve member 11 includes a restricted passage 14 passing through the valve member. In this example, the restricted passage 14 is a hole passing through the center of the valve member 11, specifically a micrometer-sized hole. The passage 14 is located at the center of the valve member 11 so that it is aligned with the first opening 15a and the central opening in the O-ring gasket 13. The valve member 11 also includes a pair of through-flow passages 16a, 16b, each of which passes through the valve member. The through-flow passages 16a, 16b are located on opposite sides of the O-ring gasket 13 and are located outside the O-ring gasket so that each through-flow passage is located between the gasket and the edge of the valve member 11. The through-flow passages 16a, 16b are wider than the restricted passage 14 passing through the center of the valve member, thereby allowing a higher fluid flow rate to pass through compared to the restricted passage 14. In other embodiments, the through-flow passage can be replaced by a bypass passage in the housing, allowing the fluid to bypass the valve member when the valve member is in an open position.

[0046] Figure 2 Shows Figure 1 In this case, the fluid flowing through the first opening 15a forces the valve member 11 to move away from the first end wall 4, overcoming the spring 12. As a result, the O-ring gasket 13 is disengaged from the first end wall 4, thereby opening the opening 15a and allowing the fluid to pass through the valve, as described below with reference to Figure 3 described.

[0047] Figure 3 The valve 1 is shown in the open position. Figure 2 15a, but with added lines indicating the direction of fluid flow through the valve. In the open position, the spring 12 is compressed by the valve member 11 under the pressure of the fluid flowing through the first opening 15a. In the open position, the gasket 13 is out of contact with the first end wall 4, thereby opening a flow path for the fluid flowing through the first opening 15a, around the gasket 13 and through the flow channels 16a, 16b. Therefore, the fluid can pass through the valve member 11, through the inner cavity of the valve, and then flow out of the valve through the second opening 15b.

[0048] In use, the check valve 1 is connected in a fluid conduit downstream of a device (e.g., an electrolyzer) so that the first opening 15a is arranged to receive fluid from the upstream device and serves as the inlet of the valve, and the second opening 15b is arranged to release the fluid from the valve to the conduit downstream of the valve, thereby serving as the outlet of the valve. In normal operation, the fluid flows along the conduit from the device to the valve, and the pressure of this forward fluid flow forces the valve member 11 to open to allow the fluid to flow through the first opening 15a, the through-flow channels 16a, 16b, and then out through the second opening 15b and proceed downstream.

[0049] Figure 4 Shows the Figure 3The opposite situation, in which the fluid backflow causes the pressure at the second opening 15b to be higher than the pressure at the first opening 15a, causes the spring 12 to return the valve member 11 to contact the first end face 4, causing the O-ring gasket 13 to seal the first opening 15a. Since the valve member 11 and the gasket 13 are in contact with the first end wall 4 of the housing 10 of the valve 1, backflow through the through-flow channels 16a, 16b and the first opening 15a is not possible because the flow path is blocked by the gasket 13 sealed on the first end wall 4. Therefore, the only allowed backflow is through the micron-scale restricted channel 14 to the opening 15a and on to the upstream device (not shown, but it can be an electrolyzer, for example). Therefore, the restricted channel 14 allows a restricted backflow of fluid through the valve back to the upstream device to balance the pressure difference on both sides of the valve caused by an external pressure shock downstream of the valve (driving the backflow back to the device) or a pressure problem in the upstream device (sucking the backflow fluid into the device).

[0050] Figure 5 Shows Figure 4 The valve 1 in which the restricted passage 14 allows the restricted fluid to flow through the opening 15a to the device upstream of the valve to avoid underpressure problems. When the valve 1 is in the closed position, it also prevents pressure surges on the equipment and only allows a limited amount of fluid to flow back upstream, which will not cause problems for the upstream equipment (such as an electrolyzer). Therefore, the valve 1 gives pressure elasticity to the upstream equipment and allows gradual pressure equalization.

[0051] An exemplary application utilizing the present invention is the discharge line of an electrolyzer. When the purge line is opened, a pressure spike outside the electrolyzer could damage the electrochemical cell stack. A common approach is to use a check valve to prevent all fluid flow. This is problematic when the electrolyzer is in standby or otherwise shut down. Underpressure may occur, which could damage the cell stack or cause the membrane to seal improperly, leading to potential mixing of hydrogen and oxygen, especially with the presence of oxygen in the hydrogen line. The presence of an open-hole check valve means that, when closed, a small amount of ambient air can enter upstream if a pressure drop occurs during idling of the electrolyzer. This prevents damage to the electrolytic cell stack by allowing pressure equalization within the cell stack or other device. Other electrochemical devices can also employ the present invention in a similar manner.

[0052] On electrochemical equipment such as electrolyzers, a discharge line is often used in order to discharge the produced products during startup and shutdown. During normal operation, the discharge line should be closed thanks to a solenoid valve that maintains the internal pressure. After closing, the discharge line opens, the fluid flows out, and the check valve will then protect the electrochemical element that may be negatively affected by external pressure spikes present in the common discharge line. In some cases, this closure may generate a dangerous underpressure between the electrochemical element and the check valve. In order to avoid this problem, it is necessary to balance the pressure with a calibrated orifice working in parallel with the check valve.

[0053] On the other hand, if a pressure spike occurs in the common discharge line, this is not dangerous for the electrochemical element because the calibrated opening will attenuate it.

[0054] The invention is not intended to be limited to the details of the above-described embodiments. For example, the invention may be constructed of any material and used with any device that benefits from the pressure resilience imparted by an orifice check valve.

[0055] It will be understood that the present invention has been described above only by way of example and that modifications of detail may be made within the scope of the invention.

[0056] Each feature disclosed in the description and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

[0057] Reference signs appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

Claims

1. A check valve, characterized in that: include: valve housing; a valve member disposed within the housing, the valve member being movable between an open position and a closed position; and at least one restricted passage through the valve member, Wherein, in the closed position, the at least one restricted passage is arranged to allow a restricted return flow of fluid through the valve.

2. The check valve according to claim 1, characterized in that: At least one further passage is included, the further passage being arranged to allow fluid to flow through or around the valve member when the valve member is in an open position.

3. The check valve according to claim 2, characterized in that: The at least one further passage is at least one bypass passage in the housing arranged to provide a fluid flow path around the valve member.

4. The check valve according to claim 2, characterized in that: The at least one further passage is at least one through-flow passage through the valve member, the through-flow passage being arranged to provide a fluid flow path through the valve member.

5. The check valve according to any one of claims 2 to 4, characterized in that: The at least one further channel has a larger cross-sectional area than the at least one restricted channel.

6. Check valve according to any one of the preceding claims, characterized in that The valve member is arranged to extend through an interior of the housing.

7. Check valve according to any one of the preceding claims, characterized in that The valve member comprises sealing means for sealing the valve member to a portion of the housing in a closed position.

8. The check valve according to claim 7, characterized in that: The sealing device is a gasket, preferably an O-ring gasket.

9. The check valve according to claim 7 or 8, characterized in that: The sealing device is arranged on the valve member to surround an inlet or an outlet of the at least one restricted passage.

10. The check valve according to any one of claims 7 to 9, characterized in that: The sealing arrangement is arranged to prevent fluid flow from an inlet of the valve housing through or around the valve element when the valve member is in a closed position.

11. Check valve according to any one of the preceding claims, characterized in that The at least one restricted passage is arranged in the center of the valve member.

12. A non-return valve according to any one of the preceding claims, characterised in that Also included is a biasing device located within the housing, the biasing device being arranged to bias the valve member toward a closed position.

13. The check valve according to claim 12, characterized in that The biasing means comprises at least one of: a spring, preferably a helical spring; An offset hinge; a poppet valve; and / or a compressible polymer.

14. The check valve according to claim 12 or 13, characterized in that: The biasing means is calibrated such that the valve member is arranged to move from the open position to the closed position at a pressure below 0.5 bar.

15. Check valve according to any one of the preceding claims, characterized in that The diameter of the at least one restricted channel is between 1 and 100 micrometers, preferably between 1 and 50 micrometers, more preferably between 1 and 20 micrometers, and even more preferably between 5 and 15 micrometers.

16. A non-return valve according to any one of the preceding claims, characterised in that The check valve is one of the following: a swing check valve; a lift check valve; a butterfly check valve; a stop check valve; or a tilting disc check valve.

17. A non-return valve according to any one of the preceding claims, characterised in that The valve member is formed from stainless steel.

18. A system, characterized in that: include: Electrochemical devices; and The non-return valve according to any one of the preceding claims, The check valve is connected to an outlet pipe of the electrochemical device.

19. The system according to claim 18, characterized in that The electrochemical device is an electrolyzer.

20. The system according to claim 19, characterized in that The outlet conduit is the discharge line of the electrolyser.

21. A system according to any one of claims 18 to 20, characterized in that The non-return valve is a non-return valve according to any one of claims 2 to 5 and wherein the total cross-sectional area of ​​the at least one further channel is greater than or equal to the cross-sectional area of ​​the outlet conduit.

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