GB2620610A

GB2620610A - Backflow suppression system

Info

Publication number: GB2620610A
Application number: GB2210312.1A
Authority: GB
Inventors: Eisenlohr Holger; Marijke Van Der Put Ella; Loudon Kai; Kirty Chaman
Original assignee: Enapter GmbH
Current assignee: Enapter GmbH
Priority date: 2022-07-13
Filing date: 2022-07-13
Publication date: 2024-01-17
Also published as: WO2024013352A2; GB202210312D0; WO2024013352A3

Abstract

A backflow suppression system 10 for an electrochemical device 3 is described. The system 10 comprises: an orifice plate arranged to be connected in an outlet pipeline of an electrochemical device. The orifice plate 2 comprises a restricted orifice 1 for restricting fluid flow through the pipeline. A valve (figure 4, 11,13,14) is also arranged to be connected in the outlet pipeline (figure 4, 15) between the electrochemical device 3 and the orifice plate 2, where it regulates fluid flow along the outlet pipeline. At least one sensor is also arranged to be connected along the outlet pipeline which is connected to a controller (figure 4, 12) so that the readings from the sensor (figure 3, 9) operate the valve in dependence on the information. The sensor(s) can be pressure, flow or temperature sensor(s). The valve may be a check valve. The electrochemical device 3 may be an electrolyser.

Description

BACKFLOW SUPPRESSION SYS1W

Field of invention

The present invention relates to a backflow suppression orifice plate and system intended for use with devices operating with a pressure differential such as hydrogen based electrochemical devices, including but not necessarily limited to electrolysers.

Background

Hydrogen is becoming more widely adopted as a means for energy storage, both long and short term and already has numerous applications in industrial processes. Hydrogen may be used in existing natural gas pipelines to provide heat, as well as electricity when used in a fuel cell.

Electrolyser are devices used for the generation of hydrogen and oxygen by splitting water. Such systems generally fall in one of three main technologies currently available, namely anion exchange membrane (AEM), proton exchange membrane (PEM), and liquid alkaline systems. Other systems, such as solid oxide electrolysis, are available.

Hydrogen can be produced either from hydrocarbons, or electrolytically in an environmentally friendly way, as disclosed in WO 2011/004343. It is preferable to generate green" hydrogen, removing the reliance upon fossil fuels.

When producing hydrogen in an electrolyser, it is possible to build a differential pressure between the anode and the cathode comprising oxygen and hydrogen respectively. The pressure difference is maintained by a membrane located between the anode and cathode. Should the membrane mechanically fail, the pressure difference will cause a flow from the higher to the lower pressure side. The subsequent mixing of the produced gases can have severe safety consequences with hydrogen and oxygen mixtures having a wide range where ignition is possible.

This is especially the case when the stack is connected to a large, pressure holding pipe and tank system downstream. If the amount of gas backflow can be limited, catastrophic consequences can be avoided.

The current state of the art in such a setting would be to employ a check valve downstream from the electrolyser or other device operating with a pressure differential. However, with the moving parts of a check valve, mechanical failure can occur meaning the safety mechanism does not provide the desired action.

The object of the present invention is to provide am improved backflow suppression system for use with a device operating with a pressure differential between fluids.

Summary of the invention

According to one aspect described herein there is provided a backflow suppression system for an electrochemical device, the system comprising: an orifice plate arranged to be connected in an outlet pipeline of an electrochemical device, the orifice plate comprising a restricted orifice for restricting fluid flow through the pipeline; a valve arranged to be connected in the outlet pipeline between the electrochemical device and the orifice plate, the valve being operable to regulate fluid flow along the outlet pipeline; at least one sensor arranged to be connected along the outlet pipeline; and a controller arranged to receive information relating to readings of the sensor and to operate the valve in dependence on the information.

Preferably, the sensor is arranged to be connected in the outlet pipeline between the valve and the orifice plate.

Preferably, the system comprises at least one further valve arranged to be connected in an inlet pipeline and/or a further outlet pipeline of an electrochemical device, the at least one further valve being operable to regulate fluid flow along the inlet pipeline and/or a further outlet pipeline.

Preferably, the controller is arranged to operate the at least one further valve in dependence on the information relating to readings of the sensor.

Preferably, the controller is arranged to operate the valve and/or at least one further valve between an open position and a closed position in dependence on the information relating to readings of the sensor.

Preferably, in the open position the valve or at least one further valve is arranged to enable fluid flow therethrough.

Preferably, the closed position the valve or at least one further valve is arranged to prevent or restrict fluid flow therethrough.

Preferably, the controller is arranged to operate the valve and/or at least one further valve when it is determined from the information relating to readings of the sensor that a parameter of the fluid flow exceeds a threshold value or falls outside a pre-set range.

Preferably, the at least one sensor comprises any one or more of a pressure sensor; a flow rate sensor; and/or a temperature sensor.

Preferably, the controller is arranged to operate the valve and/or at least one further valve when it is determined from the information relating to readings of the sensor that the pressure, flow rate, and/or a temperature of the fluid in the pipeline exceeds a threshold value or falls outside a pre-set range.

Preferably, the valve or at least one further valve is a check valve.

Preferably, the diameter of the restricted orifice is less than or equal to 3 mm.

According to another aspect described herein, there is provided a system comprising: a backflow suppression system according to any preceding claim, at least one electrochemical device, the device comprising: first and second compartments separated by a divider, the first compartment configured to operate at a first pressure and the second compartment arranged to operate at a second pressure; an outlet from the second compartment; and an outlet pipeline connected to the outlet from the second compartment, wherein the orifice plate is connected in the outlet pipeline, the valve is connected in the outlet pipeline between the electrochemical device and the orifice plate, and the sensor is connected along the outlet pipeline.

Preferably, the second pressure is higher than the first pressure.

Preferably, the second pressure is substantially equal to the pressure in the outlet pipeline between the electrochemical device and the orifice plate.

Preferably, the divider is a polymeric membrane.

Preferably, the system comprises multiple electrochemical devices and, for each device, the outlet pipeline connected to the outlet of its second compartment is connected to a shared outlet manifold arranged to receive fluid from the devices via the outlet pipelines.

Preferably, the system comprises a backflow suppression system for each respective electrochemical device Preferably, the orifice plate, valve, and sensor of the backflow suppression system for each device are connected in or along the respective outlet pipeline of that device, between the device and the shared outlet manifold.

Preferably, the system comprises multiple electrochemical devices, wherein each device comprises: an inlet pipeline connected to an inlet of the first compartment and to a shared inlet manifold arranged to supply fluid to the first compartment; and/or a further outlet pipeline connected to an outlet of the first compartment and to a shared outlet manifold arranged to receive fluid from the first compartment.

Preferably, the system comprises a backflow suppression system according to Claim 3 or 4 for each electrochemical device.

Preferably, the at least one further valve of the backflow compression system comprises at least one further valve connected: in the inlet pipeline connected to the inlet of the first compartment, between the electrochemical device and the shared inlet manifold arranged to supply fluid to the first compartment; and/or in the outlet pipeline connected to the outlet of the first compartment, between the electrochemical device and the shared outlet manifold arranged to receive fluid from the first compartment.

Preferably, the electrochemical device is an electrolyser, more preferably an AEM electrolyser, yet more preferably an AEM electrolyser operating with a dry-cathodic half cell.

As used herein, the term "region or compartment" is used to mean a part of a device which is partially enclosed, and substantially isobaric with respect to other regions of the device. In the case of an electrochemical device such as an electrolyser the anodic and cathodic compartments may be separate regions. Reference is made interchangeably to regions, compartments, and half-cells throughout.

As used herein, the term "divider" is used to mean any means for dividing regions/compartments operating at a first and second pressures.

In the preferred embodiment, the electrochemical device is an electrolyser. The electrolyser may be made from a single electrochemical cell, or a stack thereof It is envisaged that the fluids on either side of the pressure differential should not be mixed, for safety reasons or otherwise.

In an embodiment with one device, it is envisaged that downstream of the orifice plate there will be a storage vessel or equivalent with pressure higher than the operating pressure than upstream from the orifice plate. Alternatively, a plurality of devices may share an outlet manifold with the orifice plate after each device but before the manifold as described below with reference to Figure 4.

It is envisaged that the divider can be anything dividing a first and second compartment. In the preferred embodiment of an electrolyser this may be a diaphragm, or polymeric membrane such as a proton exchange membrane, or an an-ion exchange membrane. As already described, there is a pressure differential across the membrane. The first compartment at a first pressure and the second compartment operating at a second pressure. It is envisaged that the first pressure will be less than the second pressure. Alternatively, the second pressure will be lower than the first pressure. The second compartment and upstream of the orifice plate are substantially the same pressure In the preferred embodiment of an electrolyser, the inlet of the first compartment will be for electrolyte to the first, or each compartment and the outlets will be for hydrogen, the main product, in the second compartment and oxygen and spent electrolyte ion the first compartment. The oxygen and spent electrolyte may share an outlet.

For an embodiment operating with a "wet" first and second compartment, the first compartment has a first electrolyte inlet and the second compartment has its own electrolyte inlet. Each compartment may be fed from the same, or different electrolyte manifolds, the manifolds allowing for multiple devices to operate in parallel sharing balance of plant (BoP). The first compartment, being the anodic half-cell is envisaged to comprise at least one outlet for the removal of fluid. Two outlets may be provided for the removal of liquid and oxygen gas separately. The second compartment, being the cathodic half-cell, can also have a single outlet or two outlets for the removal of spent electrolyte and generated hydrogen separately. In both compartments, the gaseous outlet is envisaged to be sited such that as little liquid as possible is present in the gaseous outlet.

In an alternative embodiment of the present invention the cathode runs "dry" meaning electrolyte is not introduced to this second compartment, but only the anodic half-cell. For any device it is possible that one of the two compartments, or both, remain dry.

For a stack comprising multiple electrochemical cells, the half-cells of the same kind may share the same inlets and outlets with means for the communication of fluids between the cells of a stack being provided. This may be applied to any device.

It is envisaged that there may be a single device or 2 or more devices. In the case of a plurality of electrolysers, the inputs and outputs may be combined to a manifold to supply a grouping of devices. The inlet manifold carrying electrolyte to each stack and the outlets, for product or waste also combining in a central manifold.

In the preferred embodiment of the present invention, an orifice plate is present on each outlet pipeline downstream of the device but upstream of the manifold such that should the divider fail and the pressure differential begins to equalise, the back flow is suppressed. Preferably, a valve and sensor are also present on each outlet pipeline downstream of the device but upstream of the manifold such that failures can be detected for each device, and each device can be isolated independently from the other devices in a network of such devices. In the instance of an electrolyser this limits the amount of hydrogen mixing with oxygen reducing the likelihood of an unsafe mixture composition being formed.

The dimensioning of the size of the restricted orifice of the orifice plate is such that during normal operation at high pressure the forward pressure drop of the flow is small. Should the divider fail, there will be a backfl ow. By correctly sizing the restricted orifice, this backfl ow will be limited given the fact that the large pressure differences will lead to a choked flow. It is envisaged that the orifice may be any size but is at least half the pipe diameter, preferably smaller than 3mm, more preferably still between 0.1 mm and 2.5mm.

Whilst the orifice plate alone may be sufficient, it is preferred to combine the orifice plate with one or more sensors adapted measure any one or more of: pressure, flow rate, temperature. The sensors being provided on at least one side of the orifice plate. Preferably the sensors are provided between the device operating with a pressure differential, such as an electrolyser, and the orifice plate -the manifold or equivalent being downstream of the orifice plate.

Pressure transmitter or flow meter can be used to measure either pressure changes or mass flow rate variations. The moment when pressure is dropping (which can be set to a predetermined value based on the system requirement) or when the flow meter is observing constant mass flow rate in the backward direction, the sensor can trigger the valve which is being electrically actuated based on sensor data by the controller, via intermediary computing means, or a direct connection.

It is further envisaged that the sensors will be in communication with the controller, the controller preferably comprising computing means adapted to control the valve or alternative means for fluidly isolating the or each device.

In some embodiments, such as those with an electrolyser, the orifice plate may be upstream of the device operating with a pressure differential. If sensors are employed they too will be between the orifice plate and the device operating with a pressure differential.

Whilst there may be variations on the ordering, in the preferred embodiment, the orifice plate is downstream of the sensor, which is downstream of the valve, which is downstream of the electrochemical device. This configuration is such that in case of any failure to the electrolyser, the sensor will detect the pressure drop and also the orifice will cause a choke condition for the back flow (the condition in which the mass flow rate will remain constant even if the pressure is reducing below the critical pressure in upstream of the orifice). Considering any malfunction to the valve or sensor, the back flow will be restricted limiting the amount of hydrogen entering the oxygen side of the electrolyser before the system can be put on standby, shut down, or otherwise made safe.

In other words, the configuration is in such a way that the orifice plate acts as a supporting mechanical safety device to the valve/sensors to isolate the electrolyser and also as a primary safety device to avoid large amount of two fluids mixing in case of failure of the valve (which has moving parts) and/or sensor (which can have latency delay to detect the pressure drop or mass flow rate). This configuration also reduces the likelihood of the valve failing, but restricting the backflow flow rate and thus the fluid pressure on the valve.

In the preferred embodiment means for fluidly isolating the one or more inlet(s) and/or outlet(s) is provided by way of the at least one further valve. It is envisaged that each device may be isolated by one or more of the further valves adapted to isolate the system should abnormal fluctuations be noted in pressure, temperature or flow rate. The isolating means will be placed preferably on each inlet and/or outlet of each compartment of the device. Isolation of the inlet may be triggered if a downstream issue is determined to be present by the downstream sensors.

In embodiments with a plurality of devices utilising one or more manifolds, it is envisaged that the means for isolating are placed between the device and the manifold so that each device or group of devices can be isolated from the rest of the system without the need to isolate functioning devices.

Whilst it is envisaged that the divider may separate two compartments with any pressure differential, it is envisaged that although any pressure differential may be present it is at least 1 bar. In the preferred embodiment the pressure difference will be less than 1000 bar, more preferably still less than 500 bar, and even more preferably still below 100 bar. It is envisaged that the pressure differential will be between 1 bar and 80 bar, more preferably 5bar and 50 bar, and even more preferably substantially 35 bar.

It is envisaged that the isolating means (i.e. valve) can be sited upstream or downstream of the orifice plate but locating the valve upstream of the orifice plate is advantageous for the reasons set out above.

It is envisaged that the restricted orifice in the orifice plate may have any shape, such as but not necessarily limited to a circle, oval, triangle, quadrilateral, pentagon etc.. There may be more than one orifice, or even a mesh like plate as long as the restriction of pipe cross section allows for sufficient choking of the flow as described above.

In the preferred embodiment the backflow suppression system is used with an electrochemical device, more preferably an electrolyser, and more preferably still and AEM electrolyser, and even more preferably an AEM electrolyser operating with a dry-cathodic half cell.

The benefits of the present invention apply to devices where the separated compartments in the device operating with a pressure differential comprise constituent gases or vapours which are not intended to be mixed such as hydrogen and oxygen which when combined have a wide ratio range of volatility.

For a single electrolyser operating with dry cathode there is an anodic inlet for electrolyte to the first compat talent and an outlet from the first compartment of spent electrolyte combined with generated oxygen. There is a divider in the form of a polymeric membrane with the cathodic half-cell operating at a higher pressure of approximately 35 bar with the generated hydrogen leaving the second compartment at 35 bar.

The orifice plate and isolation valve are situated on the outlet from the second compartment, upstream of the manifold. In the event that the polymeric membrane ruptures and backflow beings, the orifice plate chokes the flow allowing time for the isolation means to activate rendering the overall device safe and limiting the chance that a potentially dangerous composition of oxygen and hydrogen will form.

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which: Figure IA is a longitudinal cross section of the orifice plate in a pipe; Figure 1B is a transverse cross section of the pipe of Figure 1A showing the orifice plate in the pipe; Figure 2 depicts the system comprising a device and orifice plate; Figure 3A depicts a variant of the system of Figure 2; Figure 3B depicts another variant of Figure 2; Figure 4 depicts a system with a plurality of electrochemical devices and orifice plates; and Figure 5 shows a compromised electrochemical device in a system in accordance with the present invention.

Detailed description

Referring to Figure IA there is seen a cross section of a pipe IOU with the orifice plate 2. Along the cross-section X-X is a cross section in another orientation showing the orifice plate front on shown in Figure lb. figure lb clearly shows the pipe walls 100 and the restricted orifice 2 in the plate 20.

Referring to Figure 2 there can be seen a system 10 in accordance with the present invention. The device 3, an electrolyser in this instance, has a first compartment 5 and a second compartment 6 separated by a divider 4, a polymeric membrane. Manifold 7 carries electrolyte into the first compartment 5 via inlet 7a. spent electrolyte and gases generated in the first compartment (oxygen) exits the first compartment 5 via the outlet 8a to manifold 8. The generated hydrogen leaves the second compartment 6 at a pressure higher than the pressure of the first compartment to flow through the outlet pipeline 1 and restricted orifice 2 in the orifice plate 20.

Figure 3a shows a system similar to that of figure 2 with the addition of a sensor 9 and valve 11, both connected to a controller, which in this example is a computing control means 12. The control means is adapted to activate the valve should a variation in pressure be measured. This prevents back flow from downstream of the electrolyser 3 should the divider 4 rupture. The orifice plate itself slows this potential backflow to ensure the safety of the overall system.

Figure 3b differs to figure 3a in that there are additional valves 13 and 14 provided on the inlets/outlets to the first compartment also connected to the computing means 12. Should a rupture in divider 4 be detected, the back flow would be slowed by the orifice plate 2, allowing the computing means to activate all fluid valves 11, 13 and 14, isolating the device and rendering the electrolyser 3 safe.

Figure 4 shows a system with a plurality of devices. A rupture in divider 4 on any one of these devices 3 would allow for back flow of hydrogen from any of the other devices to the outlet manifold 15 would thus compromise the entire system. Each orifice back flow suppression system is intended to operate independently but may be adapted to isolate the entire group of devices. This can be done using independent, or shared computing means 12. In this example, for each electrolyser the valve 11 is located between the electrolyser 3 and the manifold 15 such that each electrolyser can be independently isolated form the manifold 15 and thus from the other electrolysers. The same applies to valves 13, 14 for the inlet/outlet of the first compartment, which can be located between the electrolyser and the inlet/outlet manifolds of the first compartment. In this way, malfunctioning electrolysers can be isolated from the network of electrolysers, rendering the system safe without the need to shut down functioning electrolysers.

Figure 5 shows the system with a hole 16 in divider 4. The arrow denoting the back flow and therefore subsequent mixing of gases between the second and first compartments.

The invention is not intended to be restricted to the details of the above-described embodiment. For instance, the backflow suppression system may be used with any device and is not necessarily limited to electrolysers.

The second compartment may have an inlet as well as an outlet.

The orifice plate can be present on any of the inlets and outlets but must be on the outlet of the compartment with a higher pressure.

The invention is not intended to be restricted to the details of the above described embodiment. For instance, the present invention may be constructed of any material, and used with any device which would benefit from the pressure resilience imparted by the orifice check valve.

It will be understood that the invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

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

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

Claims

CLAIMS: 1 A backflow suppression system for an electrochemical device, the system comprising: an orifice plate arranged to be connected in an outlet pipeline of an electrochemical device, the orifice plate comprising a restricted orifice for restricting fluid flow through the pipeline; a valve arranged to be connected in the outlet pipeline between the electrochemical device and the orifice plate, the valve being operable to regulate fluid flow along the outlet pipeline; at least one sensor arranged to be connected along the outlet pipeline; and a controller arranged to receive information relating to readings of the sensor and to operate the valve in dependence on the information.
2. A system according to Claim I, wherein the sensor is arranged to be connected in the outlet pipeline between the valve and the orifice plate.
3. A system according to any preceding claim, comprising at least one further valve arranged to be connected in an inlet pipeline and/or a further outlet pipeline of an electrochemical device, the at least one further valve being operable to regulate fluid flow along the inlet pipeline and/or a further outlet pipeline.
4. A system according to Claim 3, wherein the controller is arranged to operate the at least one further valve in dependence on the information relating to readings of the sensor
5. A system according to any preceding claim, wherein the controller is arranged to operate the valve and/or at least one further valve between an open position and a closed position in dependence on the information relating to readings of the sensor.
6. A system according to Claim 5, wherein in the open position the valve or at least one further valve is arranged to enable fluid flow therethrough
7. A system according to Claim 5 or 6, wherein the closed position the valve or at least one further valve is arranged to prevent or restrict fluid flow therethrough.
8. A system according to any preceding claim, wherein the controller is arranged to operate the valve and/or at least one further valve when it is determined from the information relating to readings of the sensor that a parameter of the fluid flow exceeds a threshold value or falls outside a pre-set range.
9. A system according to any preceding claim, wherein the at least one sensor comprises any one or more of: a pressure sensor; a flow rate sensor; and/or a temperature sensor.
10. A system according to Claims 8 and 9, wherein the controller is arranged to operate the valve and/or at least one further valve when it is determined from the information relating to readings of the sensor that the pressure, flow rate, and/or a temperature of the fluid in the pipeline exceeds a threshold value or falls outside a pre-set range.
11. A system according to any preceding claim, wherein the valve or at least one further valve is a check valve.
12. A system according to any preceding claim, wherein the diameter of the restricted orifice is less than or equal to 3 mm.
13 A system comprising: a backflow suppression system according to any preceding claim; at least one electrochemical device, the device comprising: first and second compartments separated by a divider, the first compartment configured to operate at a first pressure and the second compartment arranged to operate at a second pressure; an outlet from the second compartment; and an outlet pipeline connected to the outlet from the second compartment, wherein the orifice plate is connected in the outlet pipeline, the valve is connected in the outlet pipeline between the electrochemical device and the orifice plate, and the sensor is connected along the outlet pipeline.
14. A system according to Claim 13, wherein the second pressure is higher than the first pressure.
15. A system according to Claim 13 or 14, wherein the second pressure is substantially equal to the pressure in the outlet pipeline between the electrochemical device and the orifice plate.
16. A system according to any of Claims 13 to 15, wherein the divider is a polymeric membrane.
17. A system according to any of Claims 13 to 16, comprising multiple electrochemical devices and, for each device, the outlet pipeline connected to the outlet of its second compartment is connected to a shared outlet manifold arranged to receive fluid from the devices via the outlet pipelines.
18. A system according to Claim 17, wherein the system comprises a backflow suppression system for each respective electrochemical device.
19. A system according to Claim 18, wherein the orifice plate, valve, and sensor of the backflow suppression system for each device are connected in or along the respective outlet pipeline of that device, between the device and the shared outlet manifold.
20. A system according to any of Claims 13 to 19, comprising multiple electrochemical devices, wherein each device comprises: an inlet pipeline connected to an inlet of the first compartment and to a shared inlet manifold arranged to supply fluid to the first compartment; and/or a further outlet pipeline connected to an outlet of the first compartment and to a shared outlet manifold arranged to receive fluid from the first compartment.
21. A system according to Claim 20, comprising a backflow suppression system according to Claim 3 or 4 for each electrochemical device.
22. A system according to Claim 21, wherein the at least one further valve of the backflow compression system comprises at least one further valve connected: in the inlet pipeline connected to the inlet of the first compartment, between the electrochemical device and the shared inlet manifold arranged to supply fluid to the first compartment; and/or in the outlet pipeline connected to the outlet of the first compartment, between the electrochemical device and the shared outlet manifold arranged to receive fluid from the first compartment.
23. A system according to any preceding claim, wherein the electrochemical deuce is an electrolyser.
24. A system according to Claim 23, wherein the electrolyser is an AEM electrolyser.
25. A system according to Claim 24, wherein the AEM electrolyser operates with a dry-cathodic half cell.