Adjustment of the contact pressure in an electrolysis stack

Abstract

An arrangement (1) comprising a plurality of electrolysis cells (2) and a first end plate (3) and a second end plate (4), wherein the electrolysis cells (2) are arranged adjacent to one another between the first end plate (3) and the second end plate (4), wherein the arrangement (1) further comprises a plurality of rods (5), each of which is held on the first end plate (3) and on the second end plate (4) in such a way that a respective first force (F1) directed towards the second end plate (4) is exerted on the first end plate (3) via the rods (5), and a respective second force (F2) directed towards the first end plate (3) is exerted on the second end plate (4), wherein the rods (5) are each held on at least one of the end plates (3, 4) via a respective clamping unit (6), wherein the clamping units (6) are configured to adjust the forces (F1, F2) exerted on the end plates (3, 4) by the rod (5).wherein the arrangement (1) further comprises a control (7) which is connected to the clamping units (6) and which is designed to adjust the forces (F1, F2) exerted by the rods (5) on the end plates (3, 4).

Description

[0001] The invention relates to an arrangement comprising a plurality of electrolysis cells. Furthermore, the invention relates to a method for conducting electrolysis. The invention is particularly useful for producing hydrogen on an industrial scale.

[0002] Electrolysis of water, for example, is usually carried out on an industrial scale using so-called electrolysis stacks. These consist of a large number of electrolysis cells arranged in a row. The electrolysis cells are usually held between two end plates and pressed together by tie rods. These are rods that are each connected to the two end plates and exert a force on them in the direction of the other end plate. However, when the electrolysis stack expands thermally, these forces change. These forces can also change over time. However, the aim is for the electrolysis cells to always be pressed together with the same pressure. This is desirable so that the electrolysis stack is leak-proof across the entire operating range.

[0003] It is known from the prior art to hold the tie rods to the end plates using springs. The function of the springs is to ensure that a constant load is applied to the tie rods. As the operating pressure increases (which is desired due to improved efficiency), the required compressive force exerted by the tie rods and the preloaded spring increases. This results in the need to increase the number of tie rods to limit the torque required to load the tie rods and springs. However, a high number of tie rods is disadvantageous for the following reasons.

[0004] The mechanical design of the electrolysis stack and its end plates becomes more complex with the increasing number of tie rods. With a large number of tie rods, the electrolysis stack can only be supported by its end plates. This can cause the electrolysis stack to bend downward in the center. Furthermore, the assembly of the tie rods becomes more complicated, as all tie rods should be tightened with the same torque, if possible. This is intended to ensure that the pressure is evenly distributed across the cross-section of the electrolysis cells. A similar difficulty arises when the tie rods need to be re-tightened, especially under hot conditions. Furthermore, a large number of tie rods complicates the visual inspection of the electrolysis stack.

[0005] One approach to solving this problem is described in EP 4 137 610 A1. In this approach, the concept of tie rods is abandoned entirely. Instead, the end plates are pressed together using an oil-pressure press. This press is adjusted depending on the gas pressure. Since there are no tie rods in this approach, the thermal expansion of the electrolysis stack cannot lead to the problem described above. At least to this extent, this problem is solved. However, this solution is disproportionately complex due to the press. In addition, the pressure with which the electrolysis cells are pressed together should not only be constant over time. Furthermore, it is also desirable that the pressure is distributed evenly across the cross-sectional areas of the electrolysis cells. In a design with tie rods, this can be achieved by individually adjusting the contact pressure for each tie rod.Each of the tension rods offers a degree of freedom to achieve the desired locally uniform pressure distribution across the cross-sectional areas of the electrolysis cells. In the design of EP 4 137 610 A1, this advantage of the tension rods is eliminated. The press used in EP 4 137 610 A1 offers only a single degree of freedom to adjust the pressure exerted on the electrolysis cells. Naturally, this cannot influence how the pressure is distributed across the cross-sectional area of the electrolysis cells.

[0006] The object of the present invention is to provide a simple solution for pressing electrolysis cells together with a desired pressure. In particular, this pressure should be constant over time and evenly distributed spatially.

[0007] These objects are achieved by the arrangement and method according to the independent claims. Further advantageous embodiments are specified in the dependent claims. The features presented in the claims and in the description can be combined with one another in any technologically expedient manner.

[0008] According to the invention, an arrangement is presented. The arrangement comprises a plurality of electrolysis cells and a first end plate and a second end plate, wherein the electrolysis cells are arranged adjacent to one another between the first end plate and the second end plate. The arrangement further comprises a plurality of rods, each of which is held on the first end plate and the second end plate in such a way that a respective first force directed towards the second end plate is exerted on the first end plate via the rods, and a respective second force directed towards the first end plate is exerted on the second end plate. The rods are each held on at least one of the end plates via a respective clamping unit, wherein the clamping units are configured to adjust the forces exerted on the end plates by the rod. The arrangement further comprises a control system.which is connected to the clamping units and which is designed to adjust the forces exerted by the rods on the end plates.

[0009] The arrangement is preferably configured for water electrolysis. Hydrogen and oxygen can be obtained as electrolysis products through water electrolysis. The electrolyte can be pure water or a water-containing mixture. In particular, it is preferred that the arrangement is configured for alkaline electrolysis. However, the advantages described herein can be achieved regardless of the electrolyte used and the electrolysis products obtained. The arrangement is preferably configured for high-pressure electrolysis. This is understood to mean electrolysis with an operating pressure of at least 10 bar. The advantages described below are particularly relevant in this context.

[0010] The arrangement comprises several electrolysis cells. Electrolysis can be carried out in the electrolysis cells. To obtain the electrolysis products on a large scale, several electrolysis cells are provided. Preferably, the arrangement comprises between 100 and 600 electrolysis cells. However, the advantages described herein can already be achieved if the arrangement has only two electrolysis cells.

[0011] The advantages described herein can be achieved regardless of how the electrolysis cells are constructed. The electrolysis cells can therefore be constructed like conventional electrolysis cells. The electrolysis cells can each comprise an anode compartment with an anode, a cathode compartment with a cathode, and a diaphragm arranged between the anode compartment and the cathode compartment. The anodes can be arranged within the respective anode compartment or at the edge of the respective anode compartment. The cathodes can be arranged within the respective cathode compartment or at the edge of the respective cathode compartment. For the idea described herein, it is irrelevant how the anode compartments, anodes, cathode compartments, and cathodes are designed.

[0012] The arrangement further comprises a first end plate and a second end plate. The electrolysis cells are arranged adjacent to one another between the first end plate and the second end plate. In addition to the two end plates, the arrangement can also comprise one or more intermediate plates arranged between the first end plate and the second end plate, which intermediate plates are preferably aligned parallel to the end plates. The intermediate plates can provide additional stability to the arrangement. The intermediate plates can divide the electrolysis cells into groups. The groups can be referred to as cell blocks. Such a modular design can facilitate assembly and maintenance of the arrangement.

[0013] The electrolysis cells are preferably arranged in a row along an axis, held in contact with one another. The electrolysis cells are pressed together. For this purpose, the arrangement comprises several rods. The rods are preferably tie rods. However, the term "rod" is used here to ensure that it remains unclear whether and, if so, how the term "tie rod" is clearly defined. The rods can also be referred to as tension rods or tie rods.

[0014] The arrangement comprises several rods, i.e., at least two rods. Preferably, the arrangement comprises between four and 20 rods. The rods are preferably arranged equidistantly on a circular arc that encircles the axis along which the electrolysis cells are lined up and held adjacent to one another.

[0015] The rods are each held on the first end plate and the second end plate in such a way that a first force directed toward the second end plate is exerted on the first end plate via the rods, and a second force directed toward the first end plate is exerted on the second end plate. The first force and the second force are thus opposite to each other. These two forces clamp the electrolysis cells between the end plates. Newton's third law therefore states that the two forces have the same magnitude, provided the corresponding contact surfaces are of equal size.

[0016] The electrolysis cells, end plates, and rods can also be considered an electrolysis stack. In addition to the electrolysis stack, however, the arrangement may contain other elements that are not part of the electrolysis stack. For the functionality of the arrangement, it is irrelevant where the conceptual boundary is drawn between the electrolysis stack and the other elements. Therefore, the term "arrangement" is generally used herein.

[0017] The rods are preferably made of a metal, in particular steel. However, this is not required for the idea described here. In general, it can be assumed that the rods are subject to thermal expansion. However, this is usually less than the thermal expansion of the electrolysis cells. This is because the rods are usually exposed to a lower temperature than the electrolysis cells themselves. During operation, the temperature of the rods may, for example, be only slightly higher than the ambient temperature. However, the thermal expansion of the electrolysis cells could fundamentally lead to the electrolysis cells being pressed against one another with different levels of pressure depending on the temperature. This is undesirable, however. Even independently of thermal expansion of the electrolysis cells, the pressure with which the electrolysis cells are pressed against one another can change.This is particularly due to the thermal expansion of the electrolysis cells.

[0018] In the described arrangement, the forces exerted by the rods on the end plates can be adjusted. For this purpose, the rods are each held on at least one of the end plates by a respective clamping unit. The clamping units are designed to adjust the forces exerted by the rod on the end plates. The clamping units are preferably designed as hydraulic clamping units. The clamping units can then also be referred to as hydraulic units. However, for the functioning of the arrangement described here, the principle on which the clamping units function is not important. The only important thing is that the control system can adjust the clamping units - which distinguishes the clamping units from simple springs, for example.

[0019] The clamping units can function in numerous ways. To explain how they work, we will first consider a single rod that is held to the first end plate by a clamping unit and that is firmly connected to the second end plate. For example, the rod can be firmly connected to a first part of the clamping unit, while the second end plate is firmly connected to a second part of the clamping unit. The two parts of the clamping unit are movable relative to one another along an axis of the rod. This relative movement can be brought about by changing the hydraulic pressure present in the clamping unit. For this purpose, the clamping unit can have an appropriately designed hydraulic chamber. By increasing the hydraulic pressure in the hydraulic chamber, the two end plates can be pressed more closely towards one another. This increases the pressure with which the electrolysis cells are pressed together.If, for example, a rod expands thermally, the resulting reduction in pressure on the electrolysis cells can be counteracted by increasing the hydraulic pressure in the clamping unit. Ideally, the pressure on the electrolysis cells remains unchanged. In general, the hydraulic pressure in the clamping unit can also be used to adjust how tightly the electrolysis cells are pressed together. In the simplest case, the pressure in the hydraulic chamber can be generated and maintained by a pump. However, this requires continuous operation of the pump. To avoid this, the clamping unit can also have a locking element that mechanically maintains a set pressure in the hydraulic chamber.The locking element can, for example, be locked in place and, if the setting of the clamping unit needs to be changed, can be released briefly, for example, by an electric drive. It is then sufficient to operate the pump for this short period. The locking element can, for example, be designed as a ring that interacts with one of the two parts of the clamping unit like a lock nut.

[0020] It is also possible for the clamping units to be mechanically designed, for example in the form of spindles that can be adjusted by a drive.

[0021] The described functionality can be achieved if exactly one clamping unit is provided for each of the rods. This clamping unit influences the first force exerted by the corresponding rod on the first end plate and the second force exerted by the corresponding rod on the second end plate. This results from Newton's third law. Therefore, one clamping unit per rod is sufficient to adjust both forces. It is irrelevant whether the clamping unit is attached to the first end plate or the second end plate.

[0022] In the simplest case, the rods are all held on the first end plate by a respective clamping unit. In this case, exactly one clamping unit is provided per rod. According to the above explanations, however, there are various alternatives to this simplest design with which the same effect can be achieved. For example, some of the rods can be held on the first end plate by a respective clamping unit, while the remaining rods are each held on the second end plate by a respective clamping unit. It is also possible for one or more of the rods to be held both on the first end plate by a respective clamping unit and on the second end plate by a respective clamping unit. In contrast, however, it is preferred that only exactly one of the clamping units is provided for each of the rods. This means that clamping units that are not absolutely necessary can be dispensed with.

[0023] In general, it is therefore intended that the rods are each held on at least one of the end plates by a respective clamping unit. Each of the rods is thus held on the first end plate by a respective clamping unit and / or on the second end plate by a respective clamping unit. This covers all of the previously described design options in this regard.

[0024] The arrangement further comprises a control system connected to the clamping units and configured to adjust the forces exerted by the rods on the end plates. The forces can thus be set to a desired value. The magnitude of this value and the considerations used to determine it are generally irrelevant to the design of the described arrangement. Rather, the arrangement allows the user to adjust the forces as desired.

[0025] It is sufficient for the controller to output a single output signal, which is then sent to all clamping units. In this case, all clamping units are set identically. However, a preferred embodiment is also one in which the controller outputs an individual output signal for each of the clamping units. This allows the pressure with which the electrolysis cells are pressed together to be distributed particularly evenly across the cross-section of the electrolysis cells.

[0026] The clamping units allow the forces exerted on the end plates by the tie rods to be varied during operation. This ensures the tightness of the assembly even under elevated pressure and temperature. In particular, the clamping units can maintain a desired pressure load on seals across the entire operating range, even with thermal expansion of the rods.

[0027] In addition, the clamping units allow the assembly to be operated at low temperature and low pressure with reduced torque applied to the rods. As the operating temperature and pressure increase, the clamping units allow the torque to be adjusted. This makes it possible to exploit the thermal expansion of the system (which causes the electrolysis cells to expand and puts tension on the rods). This overcomes the limitations of a design with simple threaded connections in terms of the maximum forces (that can be exerted on the threads). The rods can therefore be designed with a much larger cross-section, reducing the total number of rods required. This overcomes the problems described in the prior art regarding a large number of rods.

[0028] The described arrangement is also particularly simple. In particular, the described arrangement offers the possibility of accommodating the thermal length change of the electrolysis cells without replacing the rods with a complex press. Compared to such a solution, the described arrangement also has the advantage of retaining the advantages offered by solutions using tie rods. The rods of the described arrangement provide stability to the electrolysis cells. Furthermore, each of the rods offers a degree of freedom for adjusting the local pressure distribution across the cross-sectional area of the electrolysis cells. This allows the desired, particularly uniform local pressure distribution to be achieved.

[0029] In a preferred embodiment, the control is configured to adjust the clamping units as a function of a parameter which is a measure of a thermal change in length of the electrolysis cells in such a way that a change in the forces exerted by the rods on the end plates caused by the thermal change in length of the electrolysis cells is counteracted.

[0030] In this embodiment, the forces to be adjusted are not freely specified by the user, but are automatically determined by the controller. This allows the effect of the thermal change in length of the electrolysis cells on the contact pressure to be counteracted. As the temperature rises, the thermal change in length is thermal expansion. However, the described arrangement can not only respond to the fact that the electrolysis cells lengthen as the temperature rises. Even if the electrolysis cells become shorter again as the temperature drops, this can be taken into account. Therefore, the general reference here is to the thermal change in length of the electrolysis cells, which, depending on the temperature change, is either thermal expansion or thermal shrinkage.

[0031] It's not the change in length of the electrolysis cells themselves that is counteracted, but rather the effect of the thermal change in length of the electrolysis cells on the contact pressure. Thus, the electrolysis cells can lengthen or shorten, which is accepted.

[0032] Ideally, this setting ensures that the effect of a thermal change in the electrolysis cells is precisely compensated, so that the electrolysis cells are pressed together with a pressure that remains constant over time. However, this ideal situation is not required. It is already advantageous that the influence of a thermal change in the length of the electrolysis cells is counteracted. Compared to a design in which the change in the length of the electrolysis cells is not taken into account at all, any design in which the effects of a change in the length of the electrolysis cells are counteracted, even to a small extent, is advantageous.

[0033] In the simplest case, a dependency is stored in the controller that specifies how the clamping units should be adjusted at a given parameter value. The controller can then output a corresponding output signal to the clamping units depending on the input signal. The dependency stored in the controller can be determined experimentally, for example, once before commissioning the system. The dependency can be adjusted as needed during ongoing operation of the system.

[0034] It is sufficient for the control system to receive a single parameter as an input variable. This single parameter can be a global measure of the length changes of all electrolysis cells. This is possible if the parameter is a value that is the same for all electrolysis cells. In particular, this can be a temperature. However, the single parameter can also express the length change of a single electrolysis cell or make it possible to calculate the length change of a single electrolysis cell. Such a parameter is nevertheless a measure of the length changes of the electrolysis cells because, in general, it can reasonably be assumed that the length change of one of the electrolysis cells is also a measure of the length changes of the other electrolysis cells. The length change of one of the electrolysis cells can, for example, be measured using a strain gauge that is applied to the electrolysis cell.For example, the electrolysis cells can each have a frame surrounding the axis. The strain gauge can be mounted on this frame. It is also conceivable to measure the linear expansion of one of the electrolysis cells, for example, on a seal. In general, the linear expansion can be measured on any element subjected to stress by the rods. Thus, with appropriate calibration, numerous different ways of determining this parameter arise.

[0035] It is also possible for the controller to receive multiple parameters as input, each of which, taken individually, represents a measure of the change in length of the electrolysis cells. In this case, for example, an average value of the change in length can be calculated and used to determine an output signal. It is also possible for the controller to receive multiple parameters as input, which together represent a measure of the change in length of the electrolysis cells.

[0036] It is also possible to consider multiple parameters, each of which represents a measure of the change in length of one of the electrolysis cells. In particular, a specific parameter can be input to the control system for a subset of the electrolysis cells or even for each of the electrolysis cells, with each parameter representing a measure of the change in length of one of the electrolysis cells.

[0037] Furthermore, it is sufficient for the control system to output a single output signal, which is then sent to all clamping units. In this case, all clamping units are set identically. This is based on the generally reasonable assumption that the bars are all subject to the same thermal elongation.

[0038] However, a preferred embodiment is one in which the controller outputs an individual output signal for each of the clamping units. This allows the pressure with which the electrolysis cells are pressed together to be distributed particularly evenly across the cross-section of the electrolysis cells. This is particularly preferred when this pressure is measured in the form of several spatially resolved measured variables, and each of these measured variables is used as one of the parameters.

[0039] In principle, the parameter can be measured specifically for adjusting the clamping units. Alternatively, a variable that is also used for another purpose can be used as the parameter. In particular, this can be a variable that is already available. In this respect, the adjustment of the clamping units described here can also be carried out without additional measuring effort. Measuring the parameter specifically for adjusting the clamping units, on the other hand, has the advantage that there is no need to select from available variables. Instead, the most suitable parameter can be used. In general, this allows for a more precise result. The additional measuring effort is worth it.

[0040] It is not necessary for the parameter to be determined specifically for a specific electrolysis stack. If electrolysis is carried out with multiple electrolysis stacks, a value measured or set for one of these electrolysis stacks can be used as the parameter. This value can be used as the parameter for all electrolysis stacks.

[0041] In a further preferred embodiment of the arrangement, the parameter is a temperature, a change in length of one of the rods, a force or a pressure.

[0042] The parameter is a measure of the thermal change in length of the electrolysis cells. It is therefore not necessary for the parameter to represent the change in length of the

[0043] Electrolysis cells themselves. It is sufficient that the parameter can be used to determine the change in length of the electrolysis cells. In the present embodiment, this is utilized in the first alternative insofar as the temperature is used as a parameter. The change in length can be calculated from the temperature. However, it is not even necessary for the change in length itself to be actually calculated as a numerical value. The control can also be carried out directly using the temperature as the input variable. In the simplest case, the control system can store how the clamping units are to be adjusted at which temperature.

[0044] There are various ways to measure the temperature. The most accurate results are generally achieved in the preferred case where the temperature is the temperature of one of the electrolysis cells. The temperature of an electrolysis cell can be measured, for example, with a temperature sensor attached to the electrolysis cell or integrated into the electrolysis cell. Alternatively, the global temperature of the arrangement can also be used.

[0045] The change in length of one of the rods can also be used to determine the change in length of the electrolysis cells. Therefore, the change in length of a rod is also a measure of the change in length of the electrolysis cells. It can be assumed that the rods are subject to less thermal expansion than the electrolysis cells. This is because the rods are usually exposed to a lower temperature than the electrolysis cells themselves. However, if the electrolysis cells expand thermally, this leads to a voltage on the rods. This, in turn, can lead to a measurable change in length of the rods. This change in length can be used as the parameter in the second alternative of the present embodiment. For this purpose, a corresponding sensor can be attached to the rod.

[0046] For example, the change in length of a rod can be measured using a strain gauge attached to the rod. A change in the length of the rod then leads to a change in the load on the strain gauge. This, in turn, leads to a change in the electrical resistance of the strain gauge. This, in turn, can be measured as a change in a measuring voltage. From this, a tensile force acting on the rod can be calculated. This can alternatively or additionally be expressed as a pressure. It is irrelevant which of the previously described quantities is used as the parameter. For example, the calculated force can be used as the parameter. In particular, it is possible to use the first force or the second force as the parameter. It is also irrelevant whether a force or a resulting pressure is used as the parameter.The change in the measured voltage can also be used as the parameter without having to perform the final step of converting it into a force or pressure. In a further preferred embodiment of the arrangement, the controller is further configured to control the electrolysis, and the parameter is a variable available in the controller.

[0047] In this embodiment, the clamping units are adjusted using the same controller that also controls the electrolysis. The fact that the controller also controls the electrolysis implies that various variables are available in the controller. On the one hand, these can be variables that are output by the controller as output signals, for example, setpoints for an operating voltage, an operating temperature, or an operating pressure. On the other hand, these can also be measured values that characterize the current state of the arrangement. These can be measured values for the operating voltage, the operating temperature, or the operating pressure. If a variable available in the controller is a measure of the change in length of the electrolysis cells, this can be used as the parameter.

[0048] It is irrelevant whether the control system is formed by a single device such as a computer or by several interconnected elements. In general, it is irrelevant where the control system is physically located and which hardware the control system is implemented with. Preferably, the control system has a main element and an additional element connected to it. The main element is designed to control the electrolysis. The additional element is designed to adjust the clamping units as a function of a parameter which is a measure of a thermal change in length of the electrolysis cells, in such a way that a change in the forces exerted by the rods on the end plates caused by the thermal change in length of the electrolysis cells is counteracted. In this case, the parameter is preferably a variable available in the main element. The parameter can then be transmitted from the main element to the additional element.The additional element is preferably assigned to an electrolysis stack. It can therefore also be considered the control unit of the electrolysis stack. The main element, in contrast, can be viewed as the central system controller. The main element can control a plurality of electrolysis stacks.

[0049] In a further preferred embodiment, the arrangement further comprises a sensor connected to the controller for measuring the parameter.

[0050] If the control system comprises the main element and the associated additional element, the sensor is preferably directly connected to the additional element. This direct connection means, in particular, that the sensor is not connected to the additional element of the control system via the main element. In this embodiment, in particular, the parameter can be measured with the sensor specifically for adjusting the clamping units.

[0051] In a further preferred embodiment of the arrangement, the sensor is located on one of the electrolysis cells.

[0052] In general, it can be assumed that the parameter reflects the change in length of one of the electrolysis cells better the closer the sensor is to the electrolysis cell. For example, at a temperature, a measurement taken away from the electrolysis cell can also provide usable results. However, more accurate results can be obtained by measuring directly at the electrolysis cell. If the change in length of the electrolysis cells is used directly as the parameter, this can be done by measuring with a sensor attached to the electrolysis cell.

[0053] In a further preferred embodiment of the arrangement, the rods are held on one of the end plates via a respective one of the clamping units and are held on the other end plate via a respective spring.

[0054] The springs serve to keep the forces exerted by the rods on the end plates constant. This is known in the art. In the present embodiment, however, it is combined with the clamping units.

[0055] In this design, the clamping units also allow the forces exerted on the two end plates to be adjusted. In this respect, unlike spring-only solutions, the force exerted on the end plates by the rods can not only be kept constant, but can also be easily adjusted during operation.

[0056] In the simplest case, the rods are held to the first end plate by a respective clamping unit and to the second end plate by a respective spring. In this case, the springs are all arranged on the same side of the arrangement. This facilitates maintenance, for example. However, for the essential operating principle described here, it is irrelevant on which side the spring and on which side the clamping unit are arranged on a rod. Consequently, the rods can each be individually oriented.

[0057] As a further aspect of the invention, the use of an arrangement designed as described for producing hydrogen by electrolysis is presented.

[0058] Electrolysis is preferably water electrolysis. This produces both hydrogen and oxygen. However, water electrolysis is often carried out for hydrogen rather than oxygen. Therefore, the focus here is primarily on the production of hydrogen.

[0059] As a further aspect of the invention, a method for electrolysis is presented with an arrangement comprising a plurality of electrolysis cells and a first end plate and a second end plate, wherein the electrolysis cells are arranged adjacent to one another between the first end plate and the second end plate, wherein the arrangement further comprises a plurality of rods, each of which is held on the first end plate and on the second end plate in such a way that a respective first force directed towards the second end plate is exerted on the first end plate via the rods, and a respective second force directed towards the first end plate is exerted on the second end plate, wherein the rods are each held on at least one of the end plates via a respective clamping unit, wherein the clamping units are configured to adjust the forces exerted on the end plates by the rod, wherein the electrolysis is carried out with the arrangement,wherein the forces exerted by the rods on the end plates are adjusted via the clamping units, and wherein the clamping units are preferably adjusted as a function of a parameter which is a measure of a thermal change in length of the electrolysis cells, such that a change in the forces exerted by the rods on the end plates caused by the thermal change in length of the electrolysis cells is counteracted.

[0060] The described advantages and features of the arrangement are applicable and transferable to the method, and vice versa. The arrangement is preferably intended and configured for operation according to the method. The arrangement used in the method is preferably designed like the described arrangement. However, this is not required. In particular, the described method does not have to be carried out using an arrangement which, in addition to the electrolysis cells, also has a controller. Instead, the method can also be carried out using an arrangement which is controlled by an external controller which is not part of the arrangement. This is relevant insofar as the controller and the electrolysis cells, according to the understanding underlying this, can only be regarded as part of the same arrangement if the controller and the electrolysis cells are arranged at the same location.However, this isn't necessary for the process to function. Using communication technologies, it's possible to remotely control the process, in whole or in part. The internet makes it easy for this remote location to be anywhere in the world, potentially far from the electrolysis cells.

[0061] In a preferred embodiment of the process, the electrolysis is carried out at an operating temperature of at least 50 °C.

[0062] The higher the operating temperature, the greater the potential change in length of the electrolysis cells. Therefore, the described process is particularly suitable when the electrolysis is carried out at an operating temperature of at least 50 °C. For example, the electrolysis can be carried out at an operating temperature in the range of 50 to 100 °C, especially in the range of 70 to 90 °C.

[0063] The invention is explained in more detail below with reference to the figures. The figures show a particularly preferred embodiment, to which the invention is not limited, however. The figures and the proportions depicted therein are merely schematic. They show: Fig. 1: a side view of an arrangement according to the invention, Fig. 2: a front view of the arrangement of Fig. 1 .

[0064] Fig. 1 shows an arrangement 1 with which electrolysis can be carried out. The arrangement 1 can be used, for example, to produce hydrogen.

[0065] The arrangement 1 comprises a plurality of electrolysis cells 2 as well as a first end plate 3 and a second end plate 4. The electrolysis cells 2 are arranged adjacent to one another between the first end plate 3 and the second end plate 4. The electrolysis cells 2 are pressed together via the two end plates 3, 4. For this purpose, the arrangement 1 has eight rods 5, of which Fig. 1 four can be seen and of which in Fig. 2 all eight can be seen. The rods 5 are each held on the first end plate 3 and on the second end plate 4 in such a way that a first force F 1 directed towards the second end plate 4 is exerted on the first end plate 3 via the rods 5, and a second force F 2 directed towards the first end plate 3 is exerted on the second end plate 4. The first force F 1 and the second force F 2 press the electrolysis cells 2 together via the end plates 3, 4.

[0066] The electrolysis is preferably operated at an operating temperature of at least 50 °C. This can lead to thermal changes in the length of the electrolysis cells 2. In general, such a thermal change in length could change the forces F 1 , F 2 . However, this can be counteracted in the arrangement 1 shown. For this purpose, the rods 5 are held on the first end plate 3 by a respective clamping unit 6. The clamping units 6 are designed to adjust the forces F 1 , F 2 exerted by the rod 5 on the end plates 3, 4. The rods 5 are held on the second end plate 4 by a respective spring 9.

[0067] The arrangement 1 further comprises a controller 7, which is connected to the clamping units 6 and which is configured to adjust the clamping units 6 depending on a parameter that is a measure of a thermal change in length of the electrolysis cells 2, such that a change in the forces F 1 , F 2 exerted by the rods 5 on the end plates 3, 4, caused by the thermal change in length of the electrolysis cells 2, is counteracted. The parameter can be, for example, a temperature or a change in length of one of the rods 5.

[0068] The controller 7 has an element 13 with which this setting is made. For this purpose, element 13 receives the parameter as an input signal. This can be done in various ways.

[0069] On the one hand, the assembly 1 has a sensor 8 connected to the controller 7 for measuring the parameter. The sensor 8 is located on one of the rods 5. The sensor 8 can be a sensor for measuring a temperature or a sensor for measuring a change in length of the rod 5. A measurement signal output by the sensor 8 is processed by the controller 7 and fed to the element 13. This is illustrated by a box 10, which represents a measured value. This can be a temperature measured value or a change in length measured value.

[0070] On the other hand, the control unit 7 is also configured to control the electrolysis. Accordingly, various parameters are available in the control unit 7. One of these can be selected as the parameter used for setting the clamping units 6. This is shown in Fig. 1 This is illustrated in that the control system 7 comprises boxes 11 and 12, which represent an operating pressure and an operating temperature, respectively. These variables can also be used to determine the thermal length change of the electrolysis cells 2.

[0071] Element 13 is connected to the clamping units 6. The control unit 7 is also connected to the clamping units 6. A control signal can be output from element 13 to the clamping units 6 via this connection. This control signal can be the same for all clamping units 6 or individual for each of the clamping units 6.

[0072] Fig. 2 shows a front view of the arrangement 1 from Fig. 1 . The clamping units 6 of the eight rods 5 can be seen. The Fig. 2 The view shown is the view from the right side in Fig. 1 . It can be recognized by Fig. 2that the clamping units 6 and thus also the rods 5 are arranged equidistantly on a circular arc. List of reference symbols

[0073] 1Arrangement 2Electrolysis cell 3First end plate 4Second end plate 5Rod 6Clamping unit 7Control 8Sensor 9Spring 10Measured value 11Operating pressure 12Operating temperature 13Element F 1 first force F 2 second force

Claims

1. An arrangement (1) comprising a plurality of electrolysis cells (2) and a first end plate (3) and a second end plate (4), wherein the electrolysis cells (2) are arranged adjacent to one another between the first end plate (3) and the second end plate (4), wherein the arrangement (1) further comprises a plurality of rods (5), each of which is held on the first end plate (3) and on the second end plate (4) in such a way that a respective first force (F1) directed towards the second end plate (4) is exerted on the first end plate (3) via the rods (5), and a respective second force (F2) directed towards the first end plate (3) is exerted on the second end plate (4), wherein the rods (5) are each held on at least one of the end plates (3, 4) via a respective clamping unit (6), wherein the clamping units (6) are configured to adjust the forces (F1, F2) exerted on the end plates (3, 4) by the rod (5).wherein the arrangement (1) further comprises a control (7) which is connected to the clamping units (6) and which is designed to adjust the forces (F1, F2) exerted by the rods (5) on the end plates (3, 4).

2. Arrangement (1) according to claim 1, wherein the controller (7) is configured to adjust the clamping units (6) as a function of a parameter which is a measure of a thermal change in length of the electrolysis cells (2) in such a way that a change in the forces (F1, F2) exerted by the rods (5) on the end plates (3, 4) caused by the thermal change in length of the electrolysis cells (2) is counteracted.

3. Arrangement (1) according to claim 2, wherein the parameter is a temperature, a change in length of one of the rods (5), a force or a pressure.

4. Arrangement (1) according to one of claims 2 or 3, wherein the controller (7) is further configured to control the electrolysis and the parameter is a variable available in the controller.

5. Arrangement (1) according to one of claims 2 to 4, further comprising a sensor (8) connected to the controller (7) for measuring the parameter.

6. Arrangement (1) according to claim 5, wherein the sensor (8) is applied to one of the electrolysis cells (2).

7. Arrangement (1) according to one of the preceding claims, wherein the rods (5) are held on one of the end plates (3, 4) via a respective one of the clamping units (6) and are held on the other end plate (3, 4) via a respective spring (9).

8. Use of an arrangement (1) according to one of the preceding claims for producing hydrogen by electrolysis.

9. A method for electrolysis with an arrangement (1) comprising a plurality of electrolysis cells (2) and a first end plate (3) and a second end plate (4), wherein the electrolysis cells (2) are arranged adjacent to one another between the first end plate (3) and the second end plate (4), wherein the arrangement (1) further comprises a plurality of rods (5), which are each held on the first end plate (3) and on the second end plate (4) in such a way that a respective first force (F1) directed towards the second end plate (4) is exerted on the first end plate (3) via the rods (5) and a respective second force (F2) directed towards the first end plate (3) is exerted on the second end plate (4), wherein the rods (5) are each held on at least one of the end plates (3, 4) via a respective clamping unit (6), wherein the clamping units (6) are designed to each exert the forces exerted on the end plates (3, 4) by the rod (5) (F1,F2) to set,wherein the electrolysis is carried out with the arrangement (1), wherein the forces (F1, F2) exerted by the rods (5) on the end plates (3, 4) are adjusted via the clamping units (6).

10. The process according to claim 9, wherein the electrolysis is carried out at an operating temperature of at least 50 °C.

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