Electrolytic cell stack and method for controlling electrolytic apparatus

Abstract

To provide an electrolytic cell stack that can easily suppress gas inflow into an anode electrode.SOLUTION: According to one embodiment, an electrolytic cell stack 10A alternately stacks a plurality of electrolytic cells 11 having a diaphragm disposed between an anode electrode and a cathode electrode, and a plurality of separators 20. The separator 20 has an anode electrode flow path 22 on a surface facing the anode electrode and has a cathode electrode flow path 23 on a surface facing the cathode electrode. The electrolytic cell stack 10A has an anode upstream manifold 41 that receives and distributes anode fluid and supplies the received anode fluid to an upstream end of each anode electrode flow path 22. A vent hole 41C is formed in an upper portion of the anode upstream manifold 41, and a vent line 46 is connected to the vent hole 41C.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to an electrolysis cell stack and a method for controlling an electrolysis device. [Background technology]

[0002] Water electrolysis devices can produce hydrogen from water, and carbon dioxide electrolysis devices can produce, for example, carbon monoxide from carbon dioxide. In recent years, with growing concern about environmental issues, such electrolysis devices have become more widespread.

[0003] Hydrogen produced by a water electrolysis device can be used, for example, as fuel for fuel cells that do not emit carbon dioxide, thereby contributing to the reduction of carbon dioxide emissions. Carbon monoxide produced by a carbon dioxide electrolysis device, for example, can be used as gaseous fuel and can also be used to produce various compounds, thereby contributing to the recycling of carbon dioxide.

[0004] Water electrolysis devices and carbon dioxide electrolysis devices include an electrolysis cell in which a diaphragm is disposed between an anode and a cathode, and generate reaction products (hydrogen, carbon monoxide, etc.) by causing an electrolysis reaction in the electrolysis cell.

[0005] When generating hydrogen in a water electrolysis device, an electrolytic solution (anode fluid) containing water is supplied to the anode while a current is applied between the cathode and the anode. This causes water to be oxidized at the anode, and hydrogen ions (H + ) and oxygen (O2) are produced. The hydrogen ions pass through the membrane to the cathode, where they convert electrons (e - ) This produces hydrogen (H2) from the cathode.

[0006] When generating carbon monoxide in a carbon dioxide electrolysis device, for example, an electrolyte (anode fluid) containing water is supplied to the anode, and carbon dioxide is supplied to the cathode, and a current is applied between the cathode and the anode. This causes water to be oxidized at the anode, and hydrogen ions (H +) and oxygen (O2). The hydrogen ions pass through the membrane to the cathode, where they are converted into carbon dioxide (CO2) and hydrogen ions (H + ) and electrons (e - ) reacts with the cathode. As a result, carbon dioxide is reduced at the cathode, producing carbon monoxide (CO) and water (H2O). In addition, some of the hydrogen ions that reach the cathode can receive electrons, producing hydrogen (H2) from the cathode.

[0007] Some of the water electrolysis devices and carbon dioxide electrolysis devices described above include an electrolysis cell stack in which multiple electrolysis cells are stacked. In general, in an electrolysis cell stack, an anode fluid, such as the electrolyte solution, flows into a common flow path called a manifold and is supplied to each anode electrode from this flow path. If the anode fluid contains gas, for example, a situation may arise in which more gas flows toward some anode electrodes, resulting in variations in the amount of electrolyte solution supplied to each anode electrode. Such variations may cause variations in the state of the electrolysis reaction in each electrolysis cell. As a result, electrolysis performance may become unstable. In particular, if a large amount of gas flows toward the anode electrode, resulting in a shortage of anode fluid, the electrolysis performance at that anode electrode may decrease, and deterioration may progress due to reaction inhibition.

[0008] Therefore, in an electrolysis device, it is desirable to take measures to remove gases from the anode fluid before supplying it to the anode electrode. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-147680 [Patent Document 2] Japanese Patent Application Publication No. 2019-145334 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-162639 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-272231 [Patent Document 5] Japanese Utility Model Application Publication No. 5-50657 Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, an object of the present invention is to provide an electrolysis cell stack and a method for controlling an electrolysis device that can easily suppress the inflow of gas into the anode. [Means for solving the problem]

[0011] An electrolysis cell stack according to one embodiment alternately stacks a plurality of electrolysis cells, each having a diaphragm disposed between an anode and a cathode, and a plurality of separators. The separator has an anode flow path on the surface facing the anode, and a cathode flow path on the surface facing the cathode. The electrolysis cell stack performs an electrolysis reaction by supplying an anode fluid to at least the anode flow path and applying a current between the cathode and the anode. The electrolysis cell stack has an anode upstream manifold that receives and circulates the anode fluid and supplies the received anode fluid to the upstream ends of each of the anode flow paths. A vent hole is formed in an upper portion of the anode upstream manifold. A vent line is connected to the vent hole.

[0012] A control method for an electrolysis device according to one embodiment is a control method for an electrolysis device including the above-described electrolysis cell stack, and includes the steps of applying a current between the cathode and the anode while supplying an anode fluid to at least the anode flow path, and extracting a reaction product produced from the cathode. [Effects of the Invention]

[0013] According to the present invention, the inflow of gas into the anode electrode can be easily suppressed. [Brief explanation of the drawings]

[0014] [Figure 1A] 1 is a diagram schematically illustrating an electrolysis device including an electrolysis cell stack according to a first embodiment. [Figure 1B] FIG. 1B is a diagram showing a schematic configuration of the electrolysis device as seen from above in FIG. 1A. [Figure 2A] FIG. 1B is a schematic diagram of the electrolysis cell stack shown in FIG. 1A. [Figure 2B] FIG. 2B is an enlarged cross-sectional view of the electrolysis cell stack shown in FIG. 2A. [Figure 3A] FIG. 10 is a diagram schematically illustrating an electrolysis device including an electrolysis cell stack according to a second embodiment. [Figure 3B] FIG. 10 is a diagram illustrating a modified example of the second embodiment. [Figure 3C] FIG. 10 is a diagram illustrating another modified example of the second embodiment. [Figure 4] FIG. 10 is a diagram schematically illustrating an electrolysis device including an electrolysis cell stack according to a third embodiment. [Figure 5A] FIG. 10 is a diagram schematically illustrating an electrolysis device including an electrolysis cell stack according to a fourth embodiment. [Figure 5B] FIG. 10 is a diagram illustrating a modified example of the fourth embodiment. [Figure 6A] FIG. 10 is a diagram schematically illustrating an electrolysis device including an electrolysis cell stack according to a fifth embodiment. [Figure 6B] FIG. 13 is a diagram illustrating a modified example of the fifth embodiment. [Figure 7] FIG. 10 is a diagram schematically illustrating an electrolysis device including an electrolysis cell stack according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, each embodiment will be described with reference to the accompanying drawings.

[0016] First Embodiment FIG. 1A schematically illustrates an electrolysis device S1 including an electrolysis cell stack 10A according to a first embodiment. FIG. 1B is a diagram illustrating a schematic configuration of the electrolysis device S1 when viewed from above (plan view) in FIG. 1A. In the electrolysis device S1, the operation of the electrolysis cell stack 10A is controlled by a control device 100. Note that FIG. 1A is a diagram illustrating a cross section XX in FIG. 1B, schematically illustrating the flow direction of an anode electrode flow path 22 through which an anode fluid described below flows. The electrolysis device S1 also has a cathode electrode flow path 23 through which a cathode fluid described below flows, but the flow direction of the cathode electrode flow path 23 is not illustrated in FIG. 1A.

[0017] FIG. 2A is a schematic diagram illustrating an electrolysis cell stack 10A. FIG. 2B is an enlarged cross-sectional view of the electrolysis cell stack 10A shown in FIG. 2A. The electrolysis cell stack 10A includes a plurality of electrolysis cells 11 and a plurality of separators 20, and is configured by alternately stacking these electrolysis cells 11 and separators 20. FIG. 2B is a schematic diagram illustrating an enlarged cross-sectional view of the range indicated by the symbol Y in FIG. 2A. Note that in FIG. 2B, the upstream range of the flow path corresponding to arrow A in FIG. 2A and the downstream range of the flow path corresponding to arrow B in FIG. 2A are shown side by side for ease of explanation.

[0018] The electrolysis cell 11 is constructed by disposing a diaphragm 14 between an anode 12 and a cathode 13. The separator 20 has an anode flow path 22 on the surface facing the anode 12 and a cathode flow path 23 on the surface facing the cathode 13.

[0019] In the illustrated example, a plurality of anode flow paths 22 are formed by a plurality of grooves formed on the surface of separator 20 facing anode 12. A plurality of cathode flow paths 23 are formed by a plurality of grooves formed on the surface of separator 20 facing cathode 13.

[0020] The anode flow path 22 at least partially faces the anode 12. As will be described later, an anode fluid is supplied to the anode flow path 22, and the anode fluid is supplied from the anode flow path 22 to the anode 12. The cathode flow path 23 also at least partially faces the cathode 13. When a cathode fluid is supplied to the cathode flow path 23, the cathode fluid is supplied from the cathode flow path 23 to the cathode 13.

[0021] The anode 12 and the cathode 13 may be made of a mesh material, punched material, porous body, or porous metal fiber sintered body made of titanium (Ti), nickel (Ni), iron (Fe), or the like, a carbon substrate having a porous structure such as carbon paper or carbon cloth, or a titanium nonwoven fabric, etc. The anode 12 and the cathode 13 may be made of the same material or different materials.

[0022] The diaphragm 14 is made of an electrolyte material. Specifically, the diaphragm 14 may be composed of an ion-permeable membrane such as a solid polymer membrane (ion exchange membrane) or a solid electrolyte membrane. More specifically, the diaphragm 14 may be composed of, for example, a fluorine-based polymer membrane having sulfonic acid groups. Alternatively, the diaphragm 14 may be a porous membrane through which the electrolyte solution directly passes, thereby allowing ions to pass through the diaphragm.

[0023] The electrolysis cell stack 10A also includes two clamping plates 16 as shown in FIG. 1A. Hereinafter, the upper clamping plate 16 in FIG. 1A will be referred to as the first clamping plate 16A, and the lower clamping plate 16 in FIG. 1A will be referred to as the second clamping plate 16B. The first clamping plate 16A is placed on one end of a stack of electrolysis cells 11 and separators 20 stacked alternately, with a current collector plate and an insulating plate (not shown) interposed therebetween, and the second clamping plate 16B is placed on the other end of the stack, with a current collector plate and an insulating plate (not shown) interposed therebetween. The two clamping plates 16A, 16B are clamped together so as to approach each other, thereby holding the multiple electrolysis cells 11 and the multiple separators 20 in an overlapping state.

[0024] 1A, 1B, and 2A, the electrolysis cell stack 10A is connected to a pump 31, a reaction product receiving section 32, a power supply 33, and a voltmeter 34. In this embodiment, the electrolysis device S1 is configured as a water electrolysis device, for example. In this case, the pump 31 causes pure water, for example, as an anode fluid, to flow into the anode electrode flow path 22 of the electrolysis cell stack 10A. The reaction product receiving section 32 receives hydrogen generated by the electrolysis reaction (water electrolysis) in the electrolysis device S1 from the cathode electrode flow path 23.

[0025] 2A and 2B, the power supply 33 is connected to a current collector plate at one end of a stack in which electrolytic cells 11 and separators 20 are alternately stacked, and to a current collector plate at the other end, and applies a direct current between the cathode 13 and anode 12 of each electrolytic cell 11. A voltmeter 34 is also connected, for example, to the current collector plate at one end and the current collector plate at the other end. The voltmeter 34 measures the potential difference between the current collector plates to determine the stack voltage or cell voltage (hereinafter referred to as cell voltage), which is an indicator of the power consumed by the electrolytic cells 11 in the electrolytic cell stack 10A.

[0026] When performing an electrolysis reaction (water electrolysis) in the electrolysis cell stack 10A, pure water is supplied to each anode electrode flow path 22 of the electrolysis cell stack 10A, and a direct current is applied between the cathode electrode 13 and the anode electrode 12 of each electrolysis cell 11. At this time, at the anode electrode 12, H2O → 2H + +2e - The reaction of +½ O2 occurs. The oxygen (½·O2) produced at the anode electrode 12 is discharged from the downstream end of the anode electrode flow path 22. Cathode 13: 2H + +2e - →H2 reaction occurs. 2H + " are ions that have traveled from the anode 12 through the diaphragm 14 to the cathode 13. + " is the electron 2e that flows through the power supply circuit when a direct current is applied. -The hydrogen reacts with the cathode flow channel 23, thereby generating hydrogen. The hydrogen is then discharged from the downstream end of the cathode flow channel 23 and received in the reaction product receiving section 32 described above.

[0027] The electrolysis device S1 may be configured as a carbon dioxide electrolysis device. In this case, an anode fluid, for example, an electrolyte solution containing water and an electrolyte, is supplied to the anode 12, while a cathode fluid, for example, a gas containing carbon dioxide or an electrolyte solution containing carbon dioxide, is supplied to the cathode 13, unlike in the case of water electrolysis.

[0028] The anode fluid may be, for example, an electrolyte solution containing water and an electrolyte, such as carbonate ions (CO 2- ), phosphate ions (PO4 2- ), borate ion (BO3 3- ), sodium ions (Na + ), potassium ions (K + ), calcium ions (Ca 2+ ), lithium ion (Li + ), cesium ions (Cs + ), magnesium ions (Mg 2+ ), chloride ions (Cl - ), bicarbonate ion (HCO3 - ), hydroxide ion (OH - ) etc.

[0029] When carbon dioxide electrolysis is performed as the electrolytic reaction, a direct current is also applied between the cathode electrode 13 and the anode electrode 12 . At this time, when an electrolyte is supplied as the anode fluid to the anode electrode 12, for example, 2H2O → 4H + +O2+4e - The following reaction occurs: Oxygen (O 2 ) produced at the anode electrode 12 is discharged from the downstream end of the anode electrode flow path 22. On the other hand, at the cathode 13, 2CO2 + 4H + +4e -→The reaction of 2CO+2H2O occurs. CO is discharged from the downstream end of the cathode flow path 23 and received in the reaction product receiving section 32 described above.

[0030] The electrolysis cell stack 10A in this embodiment is a so-called internal manifold type as shown in Fig. 1A, and includes an anode upstream manifold 41, an anode downstream manifold 42, a cathode upstream manifold 43, and a cathode downstream manifold 44 (not shown in Fig. 1A, see Fig. 2B). The anode upstream manifold 41, the anode downstream manifold 42, and the cathode upstream manifold 43 and the cathode downstream manifold 44 are each formed to penetrate the electrolysis cell stack 10A at the outer periphery of each anode flow path 22 and each cathode flow path 23 in the electrolysis cell stack 10A.

[0031] The anode upstream manifold 41 is a flow path portion that receives and circulates an anode fluid (pure water for water electrolysis in this example) from the pump 31 via an anode fluid inlet pipe 410, and supplies the received anode fluid to the upstream ends of each anode flow path 22. In this embodiment, the anode upstream manifold 41 includes an internal flow path 41A formed to extend between both ends of a stack in which electrolysis cells 11 and separators 20 are alternately stacked, as shown in FIG. 1A , and an inlet-side relay flow path 41B that connects to the internal flow path 41A, penetrates the second clamping plate 16B, and is connected to the pump 31 outside the second clamping plate 16B via the anode fluid inlet pipe 410. The upstream end of the internal flow path 41A is connected to the downstream end of the inlet-side relay flow path 41B. The upstream end of the internal flow path 41A is formed by a through-hole that opens toward the second clamping plate 16B. The inlet side relay flow path 41B passes through the second clamping plate 16B and is then connected to the pump 31 via the anode fluid inlet pipe 410.

[0032] On the other hand, the anode downstream manifold 42 is a flow path portion that receives and distributes water or an electrolyte solution and / or reaction products generated by the electrolytic reaction as an anode fluid from the downstream end of each anode flow path 22. The anode downstream manifold 42 discharges the anode fluid and / or reaction products received from the downstream end of each anode flow path 22 to the outside of the electrolysis cell stack 10A via an anode fluid outlet pipe 420. The discharged anode fluid and / or reaction products may be circulated by providing a line that returns them to the pump 31 after the reaction products have been removed.

[0033] The anode downstream manifold 42 is formed to be connected to the anode upstream manifold 41 via each anode flow path 22 in the electrolysis cell stack 10A. The anode downstream manifold 42 includes an internal flow path 42A formed to extend between both ends of a stack of alternately stacked electrolysis cells 11 and separators 20, and an outlet-side relay flow path 42B connected to the internal flow path 42A, passing through the second clamping plate 16B, and extending to the outside of the second clamping plate 16B. The downstream end of the internal flow path 42A is formed by a through-hole that opens toward the second clamping plate 16B, and is connected to the upstream end of the outlet-side relay flow path 42B.

[0034] In this embodiment, the second clamping plate 16B is disposed on the lower side and the first clamping plate 16A is disposed on the upper side in the vertical direction. The electrolysis cells 11 and the separators 20 are stacked in the vertical direction, and the anode upstream manifold 41 (mainly the internal flow paths 41A) and the anode downstream manifold 42 (mainly the internal flow paths 42A) extend in the vertical direction. In this case, the anode fluid that flows from the pump 31 into the anode upstream manifold 41 via the inlet relay flow paths 41B flows from below to above and is distributed to the anode flow paths 22 of each electrolysis cell 11 along the way. The anode fluid then reaches the anodes 12 from each anode flow path 22, where an electrolysis reaction (a reaction that electrolyzes water in this example) occurs.

[0035] The anode fluid that did not electrolytically react with the anode 12 and the reaction products generated by the electrolytic reaction flow from the anode flow path 22 into the anode downstream manifold 42 and then flow out through the outlet relay flow path 42B. Along with the electrolytic reaction occurring at the anode 12, hydrogen is generated at the cathode 13 as protons receive electrons. The hydrogen is received by the reaction product receiving unit 32 from each cathode flow path 23 via the cathode downstream manifold 44 and the cathode fluid outlet pipe 440. The reaction product receiving unit 32 may separate the received hydrogen into gas and liquid and supply the resulting hydrogen to a hydrogen storage unit (not shown). Reference numeral 430 in FIG. 1B denotes a cathode fluid inlet pipe. The cathode fluid inlet pipe 430 is connected to the cathode upstream manifold 43.

[0036] In this embodiment, a vent hole 41C is formed in the upper part of the anode upstream manifold 41, and a vent line 46 is connected to the vent hole 41C. Dissolved components in the anode fluid may become gas and become mixed in the anode fluid. The vent hole 41C is provided to guide the gas contained in the anode fluid flowing through the anode upstream manifold 41 to the outside of the anode upstream manifold 41. The vent line 46 is a piping material and receives gas separated from the anode fluid through the vent hole 41C. This prevents gas from flowing into the anode flow path 22 in this embodiment. The vent line 46 extends from the connection position with the vent hole 41C, penetrating the first clamping plate 16A.

[0037] In this embodiment, the vent holes 41C are formed as through-holes that open upward from the end face of the anode upstream manifold 41 on the first fastening plate 16A side (more specifically, the end face of the internal flow path 41A on the first fastening plate 16A side). In this embodiment, the flow path from the anode upstream manifold 41 to the vent line 46 extends linearly in the vertical direction. This allows gas contained in the anode fluid flowing through the anode upstream manifold 41 to easily flow to the vent line 46, facilitating venting. The position where the vent holes 41C are formed is not particularly limited, but it is preferable that the vent holes 41C be formed above the uppermost anode flow path 22.

[0038] The vent line 46 is also connected to the anode downstream-side manifold 42. More specifically, the vent line 46 passes through the first clamping plate 16A from the vent hole 41C, then extends along the plate surface of the first clamping plate 16A toward the anode downstream-side manifold 42, and then curves toward the first clamping plate 16A and passes through the first clamping plate 16A. The downstream end of the vent line 46 is connected to a through-hole in the end face of the anode downstream-side manifold 42 on the first clamping plate 16A side (more specifically, the end face of the internal flow path 42A on the first clamping plate 16A side).

[0039] Therefore, in this embodiment, the gas received in the vent line 46 can flow into the anode downstream manifold 42. In this embodiment, the anode fluid can also flow into the vent line 46. The anode fluid that has flowed into the vent line 46 can also flow into the anode downstream manifold 42.

[0040] The connection position of the downstream end of the vent line 46 is not particularly limited. For example, the downstream end of the vent line 46 may be connected to an anode fluid outlet pipe 420 connected to the outlet-side relay flow path 42B of the anode downstream manifold 42. The anode fluid outlet pipe 420 circulates the anode fluid discharged from the outlet-side relay flow path 42B. The electrolysis cell stack 10A may also be a so-called external manifold type. In this case, a housing-shaped anode upstream manifold 41 is provided on the side of a stack in which the electrolysis cells 11 and the separators 20 are alternately stacked. In this case, a vent hole 41C may also be formed in the upper part of the anode upstream manifold 41. In this case, the vent hole 41C is also preferably formed above the uppermost anode flow path 22.

[0041] Furthermore, although the electrolytic cell 11 and the separator 20 are stacked vertically in the present embodiment, the electrolytic cell 11 and the separator 20 may also be stacked horizontally, for example, at an angle of 90° from the vertical direction. In this case, it is desirable that the vent hole 41C provided in the upper part of the anode upstream-side manifold 41 be positioned higher than the connection port in the anode upstream-side manifold 41 through which the anode fluid flows.

[0042] The control device 100 is electrically connected to the pump 31, the power supply 33, and the voltmeter 34. The control device 100 can adjust the flow rate of the anode fluid supplied by adjusting the rotation speed of the pump 31. The control device 100 can also adjust the DC current and voltage applied between the cathode 13 and the anode 12 of each electrolysis cell 11 by controlling the power supply 33. The control device 100 acquires, from the voltmeter 34, information on the cell voltage, which is an index of the power consumed by the electrolysis cell 11 in the electrolysis cell stack 10A. Based on the cell voltage information from the voltmeter 34, the control device 100 adjusts the current of the power supply 33 so that the cell voltage specified by the voltmeter 34 becomes a predetermined value, for example, at the start of operation.

[0043] Furthermore, the control device 100 is configured to increase the flow rate of the anode fluid supplied to the anode electrode 12 when the cell voltage acquired from the voltmeter 34 after the start of operation exceeds a predetermined reference value. That is, when the cell voltage acquired from the voltmeter 34 after the start of operation exceeds a predetermined reference value, the control device 100 increases the rotation speed of the pump 31 to increase the flow rate of the anode fluid. For example, if gas enters the anode electrode flow path 22 and reduces contact between the anode electrode 12 and water or the electrolyte solution as the anode fluid, the reaction resistance at the anode electrode 12 increases due to an insufficient supply of anode fluid, which can increase the cell voltage (overvoltage). In such a case, increasing the flow rate of the anode fluid promotes gas removal and allows the contact between the anode electrode 12 and the anode fluid to be adjusted to an appropriate state. This allows the cell voltage to be adjusted to an appropriate state, allows the appropriate electrolysis reaction to be performed, and suppresses the progression of deterioration of the electrolysis cell 11.

[0044] If the electrolysis device S1 is a carbon dioxide electrolysis device, the electrolysis device S1 may further be provided with a pump for supplying a cathode fluid. In this case, the control device 100 can adjust the flow rate of the supplied cathode fluid by adjusting the rotation speed of the pump for the cathode fluid.

[0045] The control device 100 may be a computer including, for example, a CPU or MPU, a ROM, etc. In this case, the control device 100 controls each unit by executing a control program stored in the ROM. The control device 100 may also be configured with other processors or electrical circuits (for example, an FPGA (Field Programmable Gate Alley)).

[0046] The operation of the electrolysis cell stack 10A according to this embodiment will be described below.

[0047] When an electrolytic reaction (water electrolysis in this example) is performed by the electrolysis device S1, the control device 100 drives the pump 31 and the power supply 33. This causes the anode fluid (pure water in this example) to flow from the pump 31 through the inlet relay flow path 41B into the anode upstream manifold 41. The anode fluid then flows from the bottom to the top within the anode upstream manifold 41, and is distributed to the anode flow paths 22 of each electrolysis cell 11 along the way.

[0048] When the anode fluid is supplied to the anode electrode 12 as described above, the anode electrode 12 converts HO to 2H + +2e - The reaction +½ O2 occurs. The oxygen (½ O2) generated at the anode 12 is discharged from the downstream end of the anode flow path 22. Specifically, the anode fluid that did not undergo the electrolytic reaction at the anode 12 and the reaction products containing the oxygen generated by the electrolytic reaction flow from the anode flow path 22 into the anode downstream manifold 42 and then flow out through the outlet relay flow path 42B to the outside. The outlet relay flow path 42B may be provided on the first clamping plate 16A instead of the second clamping plate 16B.

[0049] On the other hand, at the cathode 13, + +2e - →H2 reaction occurs. 2H + " are ions that have traveled from the anode 12 through the diaphragm 14 to the cathode 13. + " is the electron 2e that flows from the power supply circuit when a direct current is applied. - The hydrogen reacts with the cathode flow path 23, thereby generating hydrogen. The hydrogen is then discharged from the downstream end of the cathode flow path 23 and received in the reaction product receiving section 32. In other words, the hydrogen is extracted.

[0050] As described above, dissolved components may become gas and become mixed into the anode fluid supplied to the anode 12. Furthermore, in a carbon dioxide electrolysis device, when carbon dioxide comes into contact with the anode fluid in the electrolytic cell stack, the proportion of gas dissolved in the electrolyte may increase. When the anode fluid contains gas in this way, for example, more gas may flow toward some of the anode flow paths 22, which may cause variations in the amount of electrolyte supplied to each anode. Such variations may cause variations in the state of the electrolytic reaction in each electrolytic cell. As a result, the electrolysis performance may become unstable.

[0051] In contrast, in the present embodiment, a vent hole 41C is formed in the upper part of the anode upstream manifold 41, and a vent line 46 is connected to the vent hole 41C. As a result, the vent hole 41C guides gas contained in the anode fluid flowing through the anode upstream manifold 41 to the outside of the anode upstream manifold 41, and the gas is received by the vent line 46, thereby preventing the gas from flowing into the anode flow path 22. Because the vent hole 41C is formed in the upper part of the anode upstream manifold 41, gas that is lighter than the anode fluid (liquid) naturally flows toward the vent hole 41C, making it possible to easily guide the gas to the outside. This type of vent structure is easily achieved by a hole formed in the anode upstream manifold 41 and the vent line 46, which is a piping material connected to the hole.

[0052] Therefore, the electrolysis cell stack 10A according to this embodiment can easily suppress the inflow of gas into the anode electrode 12. Furthermore, by properly supplying the anode fluid to the anode electrode 12, it is possible to prevent reaction inhibition due to a shortage of pure water or electrolyte solution in the anode fluid and suppress instability in electrolysis performance. Furthermore, by suppressing the progression of deterioration of the electrolysis cell 11, it is possible to extend the life and improve the durability of the electrolysis cell stack 10A.

[0053] Furthermore, in this embodiment, the gas vent line 46 is connected to the anode downstream manifold 42. This allows the gas received in the gas vent line 46 to flow into the anode downstream manifold 42. The gas is then discharged together with the unreacted anode fluid flowing into the anode downstream manifold 42. This allows the piping of the exhaust system of the gas vent line to be realized with a simple structure.

[0054] In addition, in this embodiment, when the cell voltage of the electrolysis cell stack 10A exceeds a predetermined reference value, the flow rate of the anode fluid supplied to the anode 12 is increased. As described above, if gas enters the anode flow path 22 and reduces contact between the anode 12 and water or electrolyte as the anode fluid, the reaction resistance at the anode 12 increases due to a lack of anode fluid, which can lead to an increase in cell voltage (overvoltage). In this embodiment, when the cell voltage exceeds a predetermined reference value, it is determined that the increase in cell voltage is due to the entry of gas, as described above, and the flow rate of the anode fluid is increased. This promotes gas removal and allows the contact between the anode 12 and the anode fluid to be adjusted to an appropriate state. This allows the cell voltage to be adjusted to an appropriate state, allowing an appropriate electrolysis reaction to be performed, and suppressing the progression of deterioration of the electrolysis cell 11.

[0055] <Second embodiment> Next, an electrolysis device S2 including an electrolysis cell stack 10B according to a second embodiment will be described with reference to Fig. 3A. Components in this embodiment that are the same as those in the first embodiment are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0056] As shown in FIG. 3A , this embodiment differs from the first embodiment in that a narrow section 50 is provided in the vent line 46 described in the first embodiment. The narrow section 50 is a portion that forms a flow path with a larger pressure loss than the anode electrode flow path 22. In this embodiment, the narrow section 50 is configured with a control valve that can adjust the valve opening. The opening of the narrow section 50 may be adjusted by the control device 100 or manually. The opening of the narrow section 50 may be adjusted to be smaller than the sum of the flow path cross-sectional areas at the upstream ends of all the anode electrode flow paths 22 in the electrolysis cell stack 10B, for example. In other words, the pressure loss of the narrow section 50 may be set to be larger than the sum of the pressure losses of all the anode electrode flow paths 22 in the electrolysis cell stack 10B.

[0057] The narrow portion 50 in this embodiment is provided in a portion of the vent line 46 that extends (horizontally) along the plate surface of the first fastening plate 16A. However, the position of the narrow portion 50 is not particularly limited. The narrow portion 50 may also be configured as a flow rate restricting portion such as an orifice.

[0058] In the second embodiment, the gas vent line 46 is provided with a narrow section 50 that has a higher pressure loss than the anode electrode flow path 22, which facilitates gas flow through the gas vent line 46. This more effectively suppresses gas from flowing into the anode electrode 12. Specifically, the gas vent line 46, which is provided between the anode upstream manifold 41 and the anode downstream manifold 42, is provided with a narrow section 50 that has a pressure loss greater than the total pressure loss of all the anode electrode flow paths 22 in the electrolysis cell stack 10B. For fluids with the same pipe diameter, gases with lower density and viscosity have lower pressure loss and flow more easily than liquids. Furthermore, the smaller the pipe diameter, the higher the pressure loss and the more difficult it is for the fluid to flow. Therefore, in this embodiment, the narrow section 50 with a smaller pipe diameter facilitates gas separated from the anode fluid to flow through the gas vent line. Therefore, after the gas separated from the anode fluid rises inside the anode upstream manifold 41, it becomes possible to form a portion where the gas is likely to accumulate at a position relatively higher than the electrolysis cell stack 10B.

[0059] 3B and 3C show a modification of the second embodiment.

[0060] In the modification shown in Fig. 3B, the gas vent line 46 is connected to the anode fluid outlet pipe 420. The gas vent line 46 extends upward from the gas vent hole 41C, then extends horizontally, and then extends downward beside the stack of the electrolytic cells 11 and separators 20 to connect to the anode fluid outlet pipe 420. The narrow section 50 is provided in the gas vent line 46 in a portion that extends in the vertical direction beside the stack of the electrolytic cells 11 and separators 20. Although the narrow section 50 is configured as an orifice in Fig. 3B, it may also be configured as a control valve.

[0061] 3C, a common discharge pipe 49 is connected near the connection position of the vent line 46. The common discharge pipe 49 receives and circulates all or part of the gas and anode fluid flowing in from the vent line 46 and the anode fluid and / or reaction products flowing in from the anode downstream manifold 42 by operating an adjustment valve (not shown) in the anode fluid outlet pipe 420. The narrow section 50 is provided in a portion of the vent line 46 that extends (horizontally) along the plate surface of the first clamping plate 16A. The narrow section 50 is configured as an adjustment valve, but may also be configured as an orifice or the like.

[0062] The above-described configurations shown in FIGS. 3B and 3C also provide the same effects as those of the configuration shown in FIG. 3A.

[0063] <Third embodiment> Next, an electrolysis device S3 including an electrolysis cell stack 10C according to a third embodiment will be described with reference to Fig. 4. Components in this embodiment that are the same as those in the first and second embodiments are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0064] As shown in FIG. 4, this embodiment differs from the first embodiment in that an exhaust valve 51 and a water level detector 52 are provided in the vent line 46 described in the first embodiment. The shape of the vent line 46 also differs from that of the first embodiment. The exhaust valve 51 exhausts gas that has entered the vent line 46 to the outside. In this embodiment, the opening and closing of the exhaust valve 51 is controlled by the control device 100, but it may also be opened and closed manually. The water level detector 52 detects the water level between the anode fluid that has entered the vent line 46 and the gas phase that is generated by the accumulation of gas. In other words, the water level detector 52 detects the water level (referred to as the anode fluid height) in the vent line 46 that is pushed down by the accumulation of gas. The water level detector 52 provides the detection result to the control device 100.

[0065] The vent line 46 includes a tubular flow path portion 41C1 extending upward from the vent hole 41C, and other flow path portions extend from a position below the upper end of the tubular flow path portion 41C1. The exhaust valve 51 is connected to the upper end of the tubular flow path portion 41C1. The water level detector 52 is configured to detect the water level of the anode fluid in the space above the connection position of the other flow path portions in the tubular flow path portion 41C1.

[0066] The control device 100 opens the exhaust valve 51 when the anode fluid height (water level) detected by the water level detection unit 52 falls below a predetermined water level.

[0067] The control device 100 is also configured to open the exhaust valve 51 when the cell voltage of the electrolysis cell stack 10C exceeds a predetermined reference value. The cell voltage is identified by the detection information of the voltmeter .

[0068] Furthermore, when a predetermined time has elapsed, the control device 100 opens the exhaust valve 51. More specifically, after operation has started, the control device 100 opens the exhaust valve 51 at predetermined time intervals.

[0069] In the present embodiment, gas remaining in the vent line 46 can be discharged to the outside by opening the exhaust valve 51. If gas dissolved in the anode fluid in the piping that supplies the anode fluid remains in the anode upstream manifold 41 of the electrolysis cell stack 10C, the gas in the anode fluid may accumulate, resulting in an increase in the gas content in the anode fluid, particularly when the anode fluid is circulated. In this case, there is an increased risk of the gas flowing into the anode flow path 22. In contrast, in the present embodiment, the gas is retained in the vent line 46 and then discharged by opening the exhaust valve 51, thereby reducing this risk. As a result, in the present embodiment, the exhaust valve 51 can prevent gas from remaining in the anode upstream manifold 41 and the vent line 46, and the inflow of gas into the anode 12 can be more effectively suppressed.

[0070] Furthermore, in this embodiment, when the anode fluid contains gas, a gradually increasing amount of gas accumulates in the upper part of the tubular flow path section 41C1 of the vent line 46. As a result, the water level of the anode fluid in the tubular flow path section 41C1 gradually drops. In this embodiment, when the water level (anode fluid height) detected by the water level detection section 52 falls below a predetermined level, the accumulation of gas in the vent line 46 is detected, and the exhaust valve 51 is opened to discharge the gas. This reliably prevents gas from accumulating in the vent line 46, improving operational reliability.

[0071] Furthermore, in this embodiment, the control device 100 opens the exhaust valve 51 when the cell voltage of the electrolysis cell stack 10C exceeds a predetermined reference value. If gas enters the anode electrode flow path 22 and reduces contact between the anode electrode 12 and the anode fluid due to the gas, the reaction resistance at the anode electrode 12 increases due to a shortage of pure water or electrolyte solution in the anode fluid, which can increase the cell voltage (overvoltage). In this embodiment, when the cell voltage exceeds a predetermined reference value, the exhaust valve 51 is opened to exhaust the gas in the vent line 46, thereby facilitating venting in the anode electrode flow path 22. This normalizes the supply state of the anode fluid in the anode electrode flow path 22 and improves operational reliability.

[0072] Furthermore, in this embodiment, the control device 100 opens the exhaust valve 51 after a predetermined time has elapsed. This also prevents gas from accumulating in the vent line 46, reducing the risk of gas flowing into the anode electrode flow path 22. This improves the reliability of operation.

[0073] <Fourth embodiment> Next, an electrolysis device S4 including an electrolysis cell stack 10D according to a fourth embodiment will be described with reference to Fig. 5A. Components in this embodiment that are the same as those in the first to third embodiments are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0074] 5A, the present embodiment differs from the first embodiment in that a gas-liquid separator 53 is provided in the gas vent line 46 described in the first embodiment. The gas-liquid separator 53 separates the gas that has flowed from the anode upstream manifold 41 into the gas vent line 46 from the anode fluid, and merges the anode fluid with the anode fluid that has flowed into the anode downstream manifold 42. Meanwhile, in the present embodiment, an exhaust valve 51 similar to that in the third embodiment is connected to the gas-liquid separator 53, and by opening the exhaust valve 51, gas remaining in the gas-liquid separator 53 can be discharged as needed.

[0075] In the present embodiment, the gas-liquid separator 53 is formed as a container. The gas vent line 46 includes an upstream line 46U located upstream of the gas-liquid separator 53, and a downstream line 46D located downstream of the gas-liquid separator 53. The upstream line 46U extends upward from the gas vent hole 41C, and then extends horizontally to connect to the upper part of the gas-liquid separator 53. The downstream line 46D is connected to the gas-liquid separator 53 at a position below the connection position of the upstream line 46U. As a result, in the gas-liquid separator 53, gas accumulates at the upper side, and the anode fluid, which is a liquid, flows at the lower part and is discharged from the downstream line 46D.

[0076] According to the present embodiment described above, the risk of gas flowing into the anode electrode flow path 22 can be reduced, and the inflow of gas into the anode electrode 12 can be more effectively suppressed. That is, if components dissolved in the anode fluid become gas and remain in the piping, particularly when the anode fluid is circulated, the gas in the anode fluid can accumulate, and the mixing of gas components flowing with the anode fluid, which is mainly composed of pure water or electrolyte, can increase. In this case, the risk of gas flowing into the anode electrode flow path 22 increases. In contrast, in the present embodiment, the gas-liquid separator 53 separates the gas from the gas vent line 46 from the anode fluid and discharges it to the outside, thereby reducing the risk. This more effectively suppresses the inflow of gas into the anode electrode 12.

[0077] FIG. 5B shows a modified example of the fourth embodiment. In the modified example shown in FIG. 5B, the gas-liquid separator 53 includes a container body 53A, a gas-liquid separation membrane 53B that separates the space within the container body 53A, and a flow rate control valve 54. The upstream line 46U and downstream line 46D of the vent line 46 are connected to the space on one side of the container body 53A separated by the gas-liquid separation membrane 53B. The gas-liquid separation membrane 53B is formed of a membrane that is permeable to gas but not to liquid (a water-repellent membrane). The gas-liquid separation membrane 53B is formed, for example, of a hollow fiber membrane. A suction pump may be connected to the space on the other side of the container body 53A separated by the gas-liquid separation membrane 53B to create negative pressure. In this case, gas-liquid separation of the gas mixed in the anode fluid is promoted across the anode flow path 22 to which the gas-liquid separation membrane 53B and the vent line 46 are connected.

[0078] <Fifth embodiment> Next, an electrolysis device S5 including an electrolysis cell stack 10E according to a fifth embodiment will be described with reference to Fig. 6A. Components in this embodiment that are the same as those in the first to fourth embodiments are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0079] As shown in FIG. 6A, this embodiment differs from the modified example shown in FIG. 3B in that an exhaust valve 51, a pressure loss detector 60, and flow rate control valves 54a, 54b, and 54c are provided or replaced by the modified example of the second embodiment shown in FIG. 3B. The exhaust valve 51 is connected to the upper end of the portion of the vent line 46 that extends upward from the vent hole 41C. Specifically, the vent line 46 includes a cylindrical portion that extends upward from the vent hole 41C and a main flow path portion that extends from a position below the upper end of the cylindrical portion to the downstream end. The exhaust valve 51 is connected to the upper end of the cylindrical portion. The flow rate control valve 54a is provided at the upstream end of the main flow path portion of the vent line 46, and the flow rate control valve 54b is provided at the downstream end of the main flow path portion of the vent line 46. The flow rate control valve 54c is connected to the upstream end of the anode downstream manifold 42 via piping. The pressure loss detection unit 60 detects the pressure loss between the pressure on the downstream side of the anode electrode flow path 22 and the pressure on the upstream side.

[0080] In this embodiment, the pressure loss detection unit 60 includes an upstream pressure gauge 61 and a downstream pressure gauge 62. The upstream pressure gauge 61 detects the pressure of the anode fluid before it flows into the anode upstream manifold 41, more specifically, the pressure of the anode fluid flowing through the flow path between the pump 31 and the upstream end of the anode upstream manifold 41. The downstream pressure gauge 62 detects the pressure of the anode fluid that has flowed out of the anode downstream manifold 42, more specifically, the pressure of the anode fluid flowing through the anode fluid outlet piping 420 that is connected to the downstream end of the anode downstream manifold 42. More specifically, the downstream pressure gauge 62 detects the pressure of the anode fluid flowing through the anode fluid outlet piping 420 upstream of the connection position of the vent line 46.

[0081] The pressure loss detection unit 60 detects, as pressure loss, the difference between the pressure of the anode fluid detected by the upstream pressure gauge 61 and the pressure of the anode fluid detected by the downstream pressure gauge 62. The pressure loss detection unit 60 is electrically connected to the control device 100, and provides the control device 100 with information about the pressure loss.

[0082] Then, the control device 100 opens the flow rate adjustment valves 54a, 54b, 54c and the exhaust valve 51 when the pressure loss detected by the pressure loss detection unit 60 becomes larger than a predetermined value.

[0083] In the present embodiment described above, the exhaust valve 51 is opened when the pressure loss detected by the pressure loss detector 60 exceeds a predetermined value. When gas enters the anode electrode flow path 22, the anode fluid becomes less responsive, potentially increasing the pressure loss. Furthermore, if the gas reduces contact between the anode electrode 12 and the anode fluid, the reaction resistance at the anode electrode 12 increases due to a lack of pure water or electrolyte in the anode fluid, potentially increasing the cell voltage (overvoltage). In this embodiment, when the pressure loss exceeds a predetermined value, it is determined that a large amount of gas is flowing into the anode electrode flow path 22, and the exhaust valve 51 is opened while adjusting the pressure loss with the flow rate control valves 54a, 54b, and 54c. This exhausts the gas in the vent line 46, facilitating gas venting before and after the anode electrode flow path 22. This normalizes the supply state of the anode fluid in the anode electrode flow path 22, improving operational reliability.

[0084] 6B shows a modification of the fifth embodiment. In the modification shown in Fig. 6B, pressure loss detection unit 60 includes one differential pressure gauge. The differential pressure gauge in pressure loss detection unit 60 is connected to the flow path between pump 31 and the upstream end of anode upstream manifold 41, and to anode fluid outlet pipe 420.

[0085] Sixth Embodiment Next, an electrolysis device S6 including an electrolysis cell stack 10F according to a sixth embodiment will be described with reference to Fig. 7. Components in this embodiment that are the same as those in the first to fifth embodiments are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0086] 7, in this embodiment, the vent line 46 is closed and not connected to the anode downstream manifold 42 or the anode fluid outlet pipe 420 downstream of the anode downstream manifold 42. Specifically, the vent line 46 is composed only of a cylindrical portion extending upward from the vent hole 41C. The vent line 46 is provided with an exhaust valve 51 and a water level detector 52 similar to those in the third embodiment.

[0087] The present embodiment as described above also provides the same effects as those of the first embodiment. The exhaust valve 51 can reliably prevent gas from accumulating in the vent line 46, improving operational reliability.

[0088] Although each embodiment has been described above, the above embodiments are presented as examples and are not intended to limit the scope of the invention. Such novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Other modifications are within the scope and spirit of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims. Part of the configuration of one embodiment can be applied to other embodiments. Such configurations are also within the scope and spirit of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0089] S1, S2, S3, S4, S5, S6...Electrolysis device, 10A, 10B, 10C, 10D, 10E, 10F...Electrolysis cell stack, 11...Electrolysis cell, 12...Anode electrode, 13...Cathode electrode, 14...Diaphragm, 16...Clamping plate, 16A...First clamping plate, 16B...Second clamping plate, 20...Separator, 22...Anode electrode flow path, 23...Cathode electrode flow path, 31...Pump, 32...Reaction product receiving section, 33...Power supply, 34...Voltmeter, 41...Anode upstream side manifold, 41A...Internal flow path, 41B...Inlet side relay flow path, 41C...Vent hole, 41C1...Cylindrical flow path section, 42...Anode downstream side manifold, 42A ...internal flow path, 42B...outlet side relay flow path, 410...anode fluid inlet piping, 420...anode fluid outlet piping, 430...cathode fluid inlet piping, 440...cathode fluid outlet piping, 43...cathode upstream manifold, 44...cathode downstream manifold, 46...vent line, 46U...upstream line, 46D...downstream line, 50...narrow section, 51...exhaust valve, 52...water level detection unit, 53...gas-liquid separator, 53A...vessel body, 53B...gas-liquid separation membrane, 54, 54a, 54b, 54c...flow rate adjustment valve, 60...pressure loss detection unit, 61...upstream pressure gauge, 62...downstream pressure gauge, 100...control device

Claims

1. an electrolysis cell stack comprising a plurality of electrolysis cells, each having a diaphragm disposed between an anode and a cathode, and a plurality of separators alternately stacked one on the other, each separator having an anode electrode flow path on a surface facing the anode electrode and a cathode electrode flow path on a surface facing the cathode electrode, and an electrolysis reaction is carried out by applying a current between the cathode electrode and the anode electrode while supplying an anode fluid to at least the anode electrode flow path, an anode upstream manifold that receives and distributes the anode fluid and supplies the received anode fluid to upstream ends of each of the anode flow paths; an air vent hole formed in an upper portion of the anode upstream manifold, and an air vent line connected to the air vent hole;

2. an anode downstream manifold that receives and distributes the anode fluid and / or the reaction product produced by the electrolytic reaction from a downstream end of each of the anode flow paths; 2. The electrolysis cell stack of claim 1, wherein the vent line is connected to the anode downstream manifold.

3. The electrolysis cell stack according to claim 1 , wherein the vent line is provided with a narrowed portion that causes a larger pressure loss than the anode electrode flow path.

4. 2. The electrolysis cell stack according to claim 1, wherein the vent line is provided with an exhaust valve for exhausting gas that has entered the vent line to the outside.

5. The electrolysis cell stack according to claim 1 , wherein the vent line is provided with a gas-liquid separator.

6. The electrolysis cell stack of claim 5 , wherein the gas-liquid separator includes a gas-liquid separation membrane.

7. The electrolysis cell stack according to claim 1 , wherein water electrolysis or carbon dioxide electrolysis is performed.

8. 8. The electrolysis cell stack according to claim 7, wherein the flow rate of the anode fluid supplied to the anode electrode is increased when a cell voltage of the electrolysis cell stack exceeds a predetermined reference value.

9. 5. The electrolysis cell stack according to claim 4, wherein the exhaust valve is opened when a cell voltage of the electrolysis cell stack exceeds a predetermined reference value.

10. a pressure loss detector for detecting a pressure loss downstream of the anode flow path relative to the upstream side thereof; 5. The electrolysis cell stack according to claim 4, wherein the exhaust valve is opened when the pressure loss detected by the pressure loss detection unit exceeds a predetermined value.

11. a water level detector for detecting the water level of the anode fluid that has entered the vent line; The electrolysis cell stack according to claim 4 , wherein the exhaust valve is opened when the water level detected by the water level detection unit falls below a predetermined water level.

12. 5. The electrolysis cell stack of claim 4, wherein the exhaust valve opens after a predetermined time has elapsed.

13. A method for controlling an electrolysis apparatus including the electrolysis cell stack according to claim 1, comprising: applying a current between the cathode and the anode while supplying an anode fluid to at least the anode flow path; and removing the reaction product produced from the cathode.

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