Electrochemical system

Abstract

The invention relates to an electrochemical system (1), in particular an electrolysis system, comprising at least two modules (2), in particular electrolysis modules, each comprising at least one stack (19) which is connected to a main supply line (4) via a supply line (3) for supplying a medium, in particular water, wherein a respective at least one valve (5, 6, 7) is arranged in the supply lines (3) for switching a bypass (8) a) for bypassing the respective module (2) and / or the at least one stack (19) of the module (2) and / or b) for limiting, in particular throttling, the through-flow in the direction of the respective module (2) or the at least one stack (19).

Description

[0001] Description

[0002] Title:

[0003] Electrochemical

[0004] The invention relates to an electrochemical system, in particular an electrolysis system for generating hydrogen. However, the electrochemical system can also be a fuel cell system. The proposed electrochemical system has a modular design, meaning that it comprises at least two modules, in particular electrolysis modules.

[0005] State of the art

[0006] Electrolysis is a chemical process in which electrical current is used to break down a chemical compound. In the case of water electrolysis, hydrogen (H2) and oxygen (O2) are produced from water (H2O).

[0007] Electrolysis is carried out in an electrolyzer. This comprises a large number of electrolysis cells connected to form a stack. Well-known examples include PEM electrolysis cells (where PEM stands for "Proton Exchange Membrane"), AEL electrolysis cells (where AEL stands for "Liquid Alkaline Electrolysis"), solid oxide electrolysis cells or SOEC ("Solid Oxide Electrolyzer Cell"), or AEM electrolysis cells (where AEM stands for "Anion Exchange Membrane"). Electrolysis in the electrolysis stack also requires a power supply, a water circuit, and gas treatment, each with the associated components and lines. The power supply usually includes a transformer for converting alternating current (AC) into alternating current (AC). 1) into direct current (DC) and a rectifier to adjust the DC voltage. The water circuit typically includes water treatment to achieve the required low conductivity, a pump to supply the water, and gas-liquid separators to separate the product gases H2 and O2 from the water. Furthermore, the water circuit may include additional filters, sensors, and actuators. Gas treatment typically includes gas drying and purification. An intermediate storage tank and a compressor may also be present as additional components.

[0008] Since hydrogen is becoming increasingly important as an energy carrier in the context of decarbonization, the current goal is to produce green hydrogen, i.e. hydrogen with a very low carbon dioxide footprint, through electrolysis on a large, industrial scale, preferably with plants with capacities beyond multi-MW or 1 GW. Such plants require multiple stacks or electrolysis modules, whereby a module can consist of a single stack, several stacks, or a complete system, i.e. at least one stack including the water cycle, gas processing, and power supply. However, if each module forms a functional unit around one or a limited number of stacks, the savings that can be achieved through scaling are limited. Therefore, modular systems typically have central system components that can be shared by all or several modules.

[0009] The central components of an electrolysis system can include, in particular, components for supplying water to the individual modules, such as pipes, a pump, a heat exchanger, and a water treatment component. The water supply is then centralized, so that either all modules or none are supplied with water. This can prove disadvantageous for the reasons listed below.

[0010] For example, the stacks of individual modules may age differently, resulting in different requirements regarding water quantity and / or water temperature. In the case of severe aging and / or a safety-relevant defect in an individual stack, it may be necessary to shut it down. In this case, the entire system must be shut down, which affects the availability of the electrochemical system.

[0011] The present invention is concerned with the object of developing a modular electrochemical plant, in particular an electrolysis plant, in such a way that the above-mentioned disadvantages are avoided or at least reduced.

[0012] To achieve this object, the electrochemical system, in particular an electrolysis system, is proposed with the features of claim 1. Advantageous developments of the invention can be found in the subclaims.

[0013] Disclosure of the invention

[0014] The invention proposes an electrochemical system, in particular an electrolysis system, comprising at least two modules, in particular electrolysis modules, each comprising at least one stack connected to a main supply line via a supply line for supplying a medium, in particular water. At least one valve is arranged in each of the supply lines for switching a bypass a) to bypass the respective module and / or the at least one stack of the module and / or b) to limit, in particular throttle, the flow toward the respective module or the at least one stack.

[0015] Using the valves arranged in the supply lines, the media supply to each module can be individually adjusted. For example, the media supply to one module can be interrupted (complete limitation) or throttled (partial limitation), while the media supply to at least one other module remains unchanged. This makes it possible to create the operating conditions for each module that ensure safe and efficient operation. The operation of the entire system remains largely unaffected, thus ensuring its availability.

[0016] If the electrochemical system is an electrolysis system, the following advantages can be achieved: In the event of a fault at the module level, individual modules can be decoupled from the overall system using the valves located in the supply lines. Disconnecting or shutting down an individual module has no impact on the operation of the entire system, allowing it to continue. If necessary, the faulty module can be replaced without shutting down the entire system.

[0017] If the valves arranged in the supply lines are used to switch bypasses, the water volume supplied via the supply line—in its entirety or at least a variably adjustable partial flow—can be diverted past the respective module or at least one stack of the module by switching on or opening a bypass. In this way, the module or at least one stack can be protected from water of inadequate quality, for example, contaminated water. Other quality criteria can include the conductivity, temperature, and / or pressure of the water.

[0018] The safety of the entire system can also be increased with the help of the valves arranged in the supply lines, especially when they are used to switch bypasses. If, for example, a module requires increased flushing and / or cooling, this can be achieved while maintaining constant operation of the peripheral devices, especially while maintaining a constant pump output or pump speed. The distribution of the water volume among the modules only needs to be adjusted by switching the valves arranged in the supply lines accordingly. Individual modules may need to be temporarily shut down. This is because by reducing the number of consumers while maintaining the same water volume, the amount of water available to an individual module can be temporarily increased.

[0019] The valves arranged in the supply lines can be of various types. They preferably allow not only complete decoupling of an individual module from the overall system, but also variable distribution of a medium supplied via the supply lines to all modules.

[0020] According to a first preferred embodiment of the invention, the at least one valve arranged in a supply line of a module or a stack of the module is a directional valve, for example a 3-way valve. With the help of the directional valve, a bypass can be switched to bypass the module or the at least one stack of the module. Depending on the switching position of the directional valve, the medium is supplied to the respective module or the at least one stack or is guided past the module or stack via the bypass. Advantageously, a directional valve is used that simultaneously enables variable control of the overall flow rate and / or with regard to the distribution between the module and the bypass. The directional valve can also be combined with another valve for this purpose, for example with a throttle valve.

[0021] Alternatively or additionally, it is proposed that the at least one valve arranged in a supply line of a module or a stack of the module be a throttle valve. The throttle valve can be used to variably adjust or regulate the flow rate toward the module. Furthermore, a specific flow rate can be distributed among multiple stacks of a module using the throttle valve.

[0022] Furthermore, the at least one valve arranged in a supply line of a module or a stack of the module can be a shut-off valve. The shut-off valve can be used to interrupt the flow toward the module or at least one stack of the module, for example, to protect the module or stack from damage caused by water of inadequate quality. Regulating the flow rate is not possible using the shut-off valve.

[0023] The valves arranged in the supply lines can be designed as manually operated and / or controllable valves. The latter has the advantage that the valves can be operated automatically via a control system. This can be a central control system for the electrochemical system or a decentralized control system at the module level. In the latter case, a control unit is preferably integrated into each module.

[0024] If the valves are controllable, they can be activated under normal operating conditions depending on the duration of a specific process, such as a flushing process, and / or a temperature setting. Advantageously, the control of the valves arranged in the supply lines is initiated by suitable sensors.

[0025] In a further development of the invention, it is therefore proposed that a sensor system for detecting at least one function-relevant parameter be integrated into the main supply line and / or in the supply lines and / or in the stacks. The function-relevant parameter can be, in particular, the temperature, pressure, flow rate and / or conductivity of the respective medium or water. Other function-relevant parameters can be the electrical voltage of the electrolysis cells of a stack, the temperature difference across a stack and / or the gas composition in the installation space of a module. If a function-relevant parameter detected by the sensor system deviates from a target value, the control of a valve arranged in a supply line can be initiated.

[0026] Preferably, a pump and / or a heat exchanger and / or at least one component for media treatment, such as an ion exchanger, is / are arranged in the main supply line. Since components arranged in the main supply line are available to all modules, the number of components can be reduced in this way – especially in large systems with a large number of stacks. This helps save space and costs.

[0027] Furthermore, it is proposed that the modules and / or the at least one stack of modules are each connected on the outlet side to a media manifold via a media line. The by-products produced in the cells during the electrochemical reaction can be removed via the media lines and the media manifold. In an electrolysis plant for generating hydrogen, the by-product is oxygen. In PEM electrolysis in particular, the oxygen is produced in the reactant water that is fed in over-stoichiometrically (i.e., more water than required for the reaction). Therefore, the gas-liquid mixture is preferably fed to a gas-liquid separator via the media manifold. The separated water can then be treated, if necessary, and fed back to the modules.Preferably, the bypasses, which can be switched using the valves arranged in the supply lines to bypass the modules and / or the at least one stack of modules, each open into an outlet-side media line, so that they are fed to the gas-liquid separator together with the by-product via the media collection line. The water passed past the modules via the bypasses is thus not lost but can be made available to the modules again. The opening of the bypasses is preferably located downstream of a valve, in particular a check valve, integrated into the media line. In this way, the valve prevents medium from flowing back into the module after it has been passed past the module via a bypass.

[0028] According to a preferred embodiment of the invention, a valve for switching a bypass to bypass all modules is arranged in the main supply line. The main supply line can then be directly connected to the media collection line or the gas-liquid separator connected to it via the central or general bypass. This direct connection enables control of the fill level in the gas-liquid separator as well as rapid adjustment of the water temperature and / or conductivity.

[0029] It is further proposed that at least one module, preferably all modules, of the electrochemical system comprise multiple stacks. In this way, scaling of the system can be achieved even at the module level. The number of stacks in a module is preferably limited, for example, to five stacks per module. The multiple stacks of a module are preferably hydraulically connected in parallel so that the medium supplied to the module via the supply line is evenly distributed among all stacks. For connection to a power supply, it may be useful to electrically connect multiple stacks in series in order to achieve a suitable current-voltage ratio for the module.

[0030] As a further development, it is proposed that a mass flow sensor be integrated into the supply line of a module comprising multiple stacks. The mass flow sensor can be combined, for example, with a throttle valve. In this combination, the mass flow sensor and throttle valve can be used to ensure a uniform media flow across the stacks. One mass flow sensor can be used per module or one mass flow sensor per stack.

[0031] The invention and its advantages are described in more detail below with reference to the accompanying drawings. These show:

[0032] Fig. 1 is a schematic representation of an electrochemical plant according to the invention,

[0033] Fig. 2 is a schematic representation of another electrochemical plant according to the invention,

[0034] Fig. 3 is a schematic representation of a module for an electrochemical plant according to the invention and

[0035] Fig. 4 is a schematic representation of another module for an electrochemical plant according to the invention.

[0036] Detailed description of the drawings

[0037] The electrochemical plant 1 according to the invention shown in Figure 1 is an electrolysis plant for producing hydrogen and the by-product oxygen. Plant 1 comprises several modules 2 or electrolysis modules, each with a stack 19. The number of modules 2 can vary and is not limited to two.

[0038] During operation of system 1, water is supplied to the modules 2 via a main supply line 4, which splits into supply lines 3 assigned to the modules 2. A pump 14 is integrated into the main supply line 4 for this purpose. For water treatment, a heat exchanger 15 and an ion exchanger 16 are also integrated into the main supply line 4. Only then does the main supply line 4 split into the supply lines 3. Valves 5 designed as 3-way valves are arranged in the supply lines 3 for switching bypasses 8, which allow the respective module 2 to be bypassed. The amount of water supplied via the supply lines 3 can thus be supplied to the respective module 2 or routed via the bypass 8, whereby the amount of water routed via the bypass 8 or the amount of water supplied to module 2 can preferably be variably adjusted via the valve 5.Whether and / or when a bypass 8 is activated depends in particular on the sensor data of a sensor system 9, which is also integrated into the supply lines 3 and which can detect at least one function-relevant parameter. To reduce the number of sensors, the sensor system 9 can also be integrated into the main supply line 4.

[0039] The electrochemical reaction in the stacks 19 produces hydrogen and oxygen, which are separately discharged via corresponding media lines and each fed to a gas-liquid separator 12 via media manifolds. The media lines 10, which collect the oxygen together with the supplied water, combine to form a media manifold 11, via which the modules 2 are connected to a first gas-liquid separator 12. In the gas-liquid separator 12, oxygen and liquid water are separated, and the liquid water is reintroduced into the main supply line 4 so that it can be made available to the modules 2 again. Since a further valve 17 for switching a further bypass 18 is integrated into the main supply line 4 in this case, the main supply line 4 can be connected directly to the media manifold 11 or the gas-liquid separator 12 connected to it, bypassing all modules 2.However, the additional valve 17 and the additional bypass 18 are optional and therefore not absolutely necessary.

[0040] The scope of a module 2 can be essentially limited to a stack 19, as shown by way of example in Figure 1. The lines 3, 10, the valve 5, the sensor 9, and the bypass 8 are then arranged outside the module 2. Optionally, the lines 3, 10, the valve 5, the sensor 9, and / or the bypass 8 can be integrated into the module 2.

[0041] Figure 2 shows a modification of system 1 in Figure 1. The modules 2 of system 1 in Figure 2 have not just one stack 19, but several stacks 19. The number of stacks 19 can vary and is not limited to two. The stacks 19 of a module 2 are hydraulically connected in parallel so that the amount of water supplied to the modules 2 via the supply lines 3 is distributed among the several stacks 19. For this purpose, the supply line 3 splits into further lines, but only downstream of the valve 5 arranged in the supply line 3 for switching the bypass 8. This means that when the bypass 8 is open, no stack 19 is supplied with water or the amount of water for all stacks 19 is limited. The stacks 19 of a module 2 can be electrically connected in series.It is also possible that the distribution of the water quantity between the stacks 19 of a module 2 can be controlled by additional throttle valves (not shown) in front of all or individual stacks 19.

[0042] Figure 3 shows a single module 2 for a system 1 according to the invention. The module 2 is supplied with water via a supply line 3. A sensor 9 is integrated into the supply line 3, which detects at least one function-relevant parameter. Depending on the detected values ​​of the at least one parameter, a valve 5 is controlled, which in turn is designed as a 3-way valve and serves to switch a bypass 8. Depending on the switching position of the 3-way valve, the entire water quantity or a variably adjustable partial flow is directed via the bypass 8. Downstream of the valve 5, another valve is arranged, which can be a throttle valve 6 or a shut-off valve 7. In the case of a shut-off valve 7, the supply line 3 can be completely shut off, for example, for the removal of the module 2.A further valve 13 in the form of a check valve arranged on the outlet side in a media line 10 prevents water from flowing back from the bypass 8 into the module 2.

[0043] Figure 4 shows a single module 2 for a system 1 according to the invention with multiple stacks 19. The supply line 3 is further divided to supply each stack 19 with water. To ensure even distribution of the water among all stacks 19, a throttle valve (not shown) with a mass flow sensor (not shown) can be installed upstream of each stack 19. These components can be used to set a uniform volume flow across all stacks 19 during commissioning.

Claims

Claims 1. Electrochemical plant (1), in particular electrolysis plant, with at least two modules (2), in particular electrolysis modules, each comprising at least one stack (19) which is connected to a main supply line (4) via a supply line (3) for supplying a medium, in particular water, wherein in each of the supply lines (3) at least one valve (5, 6, 7) is arranged for switching a bypass (8) a) for bypassing the respective module (2) and / or the at least one stack (19) of the module (2) and / or b) for limiting, in particular throttling, the flow in the direction of the respective module (2) or the at least one stack (19).

2. Electrochemical plant (1), in particular electrolysis plant, according to claim 1, characterized in that the at least one valve is a directional control valve (5), for example a 3-way valve, a throttle valve (6) and / or a shut-off valve (7).

3. Electrochemical plant (1), in particular electrolysis plant, according to claim 1 or 2, characterized in that a sensor system (9) for detecting at least one function-relevant parameter is integrated into the main supply line (4) and / or into the supply lines (3) and / or into the stacks (19).

4. Electrochemical plant (1), in particular electrolysis plant, according to one of the preceding claims, characterized in that a pump (14) and / or a heat exchanger (15) and / or at least one component for media treatment, for example an ion exchanger (16), is / are arranged in the main supply line (4).

5. Electrochemical plant (1), in particular electrolysis plant, according to claim 4, characterized in that the modules (2) and / or the at least one stack (19) of the modules (2) are each connected on the outlet side to a media collecting line (11) via a media line (10).

6. Electrochemical plant (1), in particular electrolysis plant, according to one of the preceding claims, characterized in that the bypasses (8) for bypassing the modules (2) and / or the at least one stack (19) of the modules (2) each open into an outlet-side media line (10), preferably downstream of a valve (13), in particular a check valve, integrated into the media line (10).

7. Electrochemical plant (1), in particular electrolysis plant, according to one of the preceding claims, characterized in that in the main supply line (4) a valve (17) is arranged to switch a bypass (18) to bypass all modules (2).

8. Electrochemical plant (1), in particular electrolysis plant, according to one of the preceding claims, characterized in that at least one module (2), preferably all modules (2), comprise several stacks (19) which are preferably hydraulically connected in parallel.

9. Electrochemical plant (1), in particular electrolysis plant, according to claim 8, characterized in that a mass flow sensor is integrated in the supply line (3) of a module (2) having several stacks (19).

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