Electrochemical system
By using pressure sensors and control units in the electrochemical system to detect damage to the electrolyte membrane, and using exhaust devices and shutdown valves to prevent gas leakage, the equipment failure caused by electrolyte membrane damage is solved, and the stable operation of the system is achieved.
Patent Information
- Application Number
- CN202311702230.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-12
- Filing Date
- 2023-12-12
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2043-12-12
AI Technical Summary
In an electrochemical system, when a large pressure difference occurs on the anode and cathode sides of the electrolyte membrane, damage to the electrolyte membrane causes gas leakage on the high-pressure side, which may lead to failure of other equipment.
By adopting an electrochemical system including a first stack, a first storage tank, a check valve, a first pressure sensor, a second pressure sensor and a control unit, the pressure difference between the second pressure sensor and the first pressure sensor is detected, Determine whether the electrolyte membrane is damaged, and when damage is detected, it is detected to prevent gas leakage through the exhaust device and the shut-off valve to protect other equipment.
Effectively detect and prevent gas leakage caused by electrolyte membrane damage, prevent equipment failure, and ensure the stable operation of the system.
Smart Images
Figure CN118186420B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an electrochemical system for generating gas through electrochemical reaction. Background Art
[0002] Various electrochemical systems have been proposed, which use a stack with an electrolyte membrane to electrochemically generate gas or electrochemically pressurize gas. For example, Japanese Patent Publication No. 2022-29892 describes an electrochemical system that decomposes water supplied as a raw material through a water electrolysis stack to generate oxygen and hydrogen, and stores them as compressed gas in an oxygen tank and a hydrogen tank. Summary of the invention
[0003] In the electrochemical system described above, a stack is sometimes used under conditions where a large pressure difference is generated between the anode side and the cathode side of the electrolyte membrane. If the electrolyte membrane in such a stack is damaged, the gas on the high pressure side leaks to the low pressure side, which may cause failure of other equipment.
[0004] The purpose of the present invention is to solve the above technical problems.
[0005] One method disclosed below is an electrochemical system, comprising a first battery stack, a first tank, a check valve, a first pressure sensor, a second pressure sensor and a control unit, wherein the first battery stack has a membrane electrode assembly in which an electrolyte membrane is clamped by a first electrode and a second electrode; the first tank stores a high-pressure first gas output by the first battery stack; the check valve is arranged in a flow path connecting the first battery stack and the first tank; the first pressure sensor is connected to the flow path upstream of the check valve; the second pressure sensor is connected to the flow path downstream of the check valve; the control unit detects whether the electrolyte membrane is damaged based on the detection pressures of the first pressure sensor and the second pressure sensor, and when the pressure difference obtained by subtracting the detection pressure of the first pressure sensor from the detection pressure of the second pressure sensor exceeds a specified pressure, the control unit determines that the electrolyte membrane is damaged.
[0006] The electrochemical system of the above aspect can protect other devices connected to the first cell stack by detecting leakage of the first gas due to damage to the electrolyte membrane.
[0007] The above-mentioned objects, features, and advantages will be easily understood from the following description of the embodiments described with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Figure 1 It is a diagram showing the structure of the electrochemical system according to the first embodiment.
[0009] Figure 2 Yes means Figure 1 Flowchart of the action of the electrochemical system.
[0010] Figure 3 It is a diagram showing the structure of an electrochemical system according to a second embodiment.
[0011] Figure 4 It is a diagram showing the structure of an electrochemical system according to a third embodiment.
[0012] Figure 5 It is a diagram showing the structure of an electrochemical system according to a fourth embodiment. DETAILED DESCRIPTION
[0013] (First embodiment)
[0014] The electrochemical system 10 of the present embodiment is a water electrolysis system that electrolyzes water by supplying electric power from the outside. The electrochemical system 10 generates a first gas (oxygen in the present embodiment) and a second gas (hydrogen in the present embodiment). The electrochemical system 10 has a function of boosting the pressure of the electrochemical gas, and stores the first gas in a compressed state in a first storage tank 12 (oxygen storage tank), and stores the second gas in a compressed state in a second storage tank 14 (hydrogen storage tank). The electrochemical system 10 is used, for example, in an energy storage system that stores excess electrical energy in the form of oxygen and hydrogen. Below, the structure of the electrochemical system 10 is described.
[0015] The electrochemical system 10 mainly includes a first cell stack 16, a hydrogen boost cell stack 18, a gas-liquid separator 20, a first tank 12, a second tank 14, a water tank 22, and a control unit 24. The control unit 24 is configured as a computer having a CPU and a memory.
[0016] The first cell stack 16 of the present embodiment is a water electrolysis stack 17. The water electrolysis stack 17 includes a membrane electrode assembly 27 in which an electrolyte membrane 26 is sandwiched between a first electrode (anode) 26a and a second electrode (cathode) 26c. The electrolyte membrane 26 is, for example, a cell that transports hydroxide ions OH - The membrane electrode assembly 27 is sandwiched by the separator 29, thereby forming a single cell 30. The first battery stack 16 has a battery stack 31 in which several tens to several hundreds of layers of single cells 30 are stacked. The battery stack 31 is driven by current supplied from the anode 26a and the cathode 26c in the stacking direction.
[0017] Each single cell 30 generates oxygen gas from the anode 26a and hydrogen gas from the cathode 26c. Water is supplied to the cathode 26c through the supply flow path 42. The cathode 26c decomposes part of the water into hydrogen ions H by electrochemical reaction. + and hydroxide ions OH- . Hydrogen ion H + The cathode 26 c receives electrons on its surface and becomes hydrogen. The hydrogen generated at the cathode 26 c passes through the second flow path 46 together with water and is discharged from the first cell stack 16. The hydrogen and water pass through the second flow path 46 and flow into the gas-liquid separator 20.
[0018] Hydroxide ion OH - The hydroxide ions OH are transported to the anode 26a through the electrolyte membrane 26. - Electrons are released on the surface of the anode 26a to generate oxygen and water. Oxygen is gathered through the flow path inside the first battery stack 16 and flows out of the first battery stack 16. Oxygen is stored in the first tank 12 through the first flow path 44. Accordingly, the pressure of the oxygen stored in the first tank 12 through the first flow path 44 is higher than the pressure of the hydrogen flowing into the gas-liquid separator 20 through the second flow path 46.
[0019] A back pressure valve 48 is disposed in the first flow path 44. The back pressure valve 48 maintains the pressure of the oxygen in the first flow path 44 at a predetermined pressure of, for example, 1 to 100 MPa. The oxygen that has passed through the back pressure valve 48 is stored in the first storage tank 12. Therefore, each unit cell 30 is used in a state where a high pressure difference is generated between the anode 26a and the cathode 26c of the electrolyte membrane 26. The water generated at the anode 26a returns to the cathode 26c through the electrolyte membrane 26 by utilizing the pressure difference between the anode 26a and the cathode 26c, and flows into the second flow path 46.
[0020] A check valve 50 is provided in the middle of the first flow path 44. The check valve 50 is located between the back pressure valve 48 and the first cell stack 16. The check valve 50 allows oxygen to flow only in the direction from the first cell stack 16 to the first tank 12, and prevents oxygen from flowing back from the first tank 12 to the first cell stack 16.
[0021] The electrochemical system 10 includes a first pressure sensor 52 connected to the first flow path 44 upstream of the check valve 50, and a second pressure sensor 54 connected to the first flow path 44 downstream of the check valve 50. The first pressure sensor 52 detects the pressure of oxygen in the first flow path 44 upstream of the check valve 50. The second pressure sensor 54 detects the pressure of oxygen in the first flow path 44 downstream of the check valve 50. The detection results of the first pressure sensor 52 and the detection results of the second pressure sensor 54 are input to the control unit 24.
[0022] The control unit 24 detects whether the electrolyte membrane 26 is damaged based on the detection results of the first pressure sensor 52 and the detection results of the second pressure sensor 54. Specifically, when the pressure difference ΔP obtained by subtracting the pressure detected by the first pressure sensor 52 from the pressure detected by the second pressure sensor 54 exceeds a predetermined pressure, the control unit 24 determines that the electrolyte membrane 26 is damaged.
[0023] The supply flow path 42 connects the water storage part 20w of the gas-liquid separator 20 and the first battery stack 16. The water storage part 20w is the part in the gas-liquid separator 20 that stores water. The supply flow path 42 supplies water stored in the water storage part 20w of the gas-liquid separator 20 to the first battery stack 16. If necessary, a pump for supplying water to the first battery stack 16 may also be provided in the supply flow path 42. The second flow path 46 connects the gas-liquid separator 20 and the first battery stack 16, and guides the fluid containing water and hydrogen discharged from the first battery stack 16 to the gas-liquid separator 20.
[0024] The gas-liquid separator 20 separates the fluid flowing into the second flow path 46 into hydrogen gas and liquid water. The gas-liquid separator 20 separates water from hydrogen gas by gravity or centrifugal force. The water separated by the gas-liquid separator 20 is stored in the water storage part 20w, and the hydrogen gas is collected in the gas recovery part 20g.
[0025] The water stored in the water storage section 20w returns to the first battery stack 16 through the supply flow path 42. The water circulates between the gas-liquid separator 20 and the first battery stack 16 through the second flow path 46 and the supply flow path 42. The amount of water circulating between the gas-liquid separator 20 and the first battery stack 16 decreases as the electrochemical reaction of the first battery stack 16 proceeds. In order to replenish the reduced water, the electrochemical system 10 has a water storage tank 22. The water storage tank 22 keeps the water level of the water storage section 20w constant by supplying water to the water storage section 20w of the gas-liquid separator 20.
[0026] The exhaust device 56 is a device for exhausting the gas inside the second flow path 46 and the gas-liquid separator 20. The exhaust device 56 exhausts the gas inside the second flow path 46 and the gas-liquid separator 20 according to the control of the control unit 24. When the pressure difference ΔP between the pressure detected by the first pressure sensor 52 and the pressure detected by the second pressure sensor 54 exceeds the specified pressure, that is, when damage to the electrolyte membrane 26 is detected, the control unit 24 controls the exhaust device 56 to exhaust the gas. When the external environment is a vacuum, the exhaust device 56 is composed of an exhaust path 58 and an exhaust valve 60 that opens and closes the exhaust path 58. In addition, when the electrochemical system 10 is configured in the atmosphere or in water, the exhaust device 56 can be composed of a combination pump and a valve.
[0027] The gas-liquid separator 20 is connected to a second back-pressure valve 62 . The second back-pressure valve 62 maintains the second flow path 46 at a predetermined pressure lower than that of the first flow path 44 .
[0028] The hydrogen after water is separated by the gas-liquid separator 20 is guided to the hydrogen booster stack 18 through the third flow path 64. The electrochemical system 10 has a shutoff valve 66 and a catalyst device 68 in the middle of the third flow path 64. The shutoff valve 66 is located upstream of the catalyst device 68 on the third flow path 64. The shutoff valve 66 is a valve capable of closing the third flow path 64, and performs opening and closing actions according to the control of the control unit 24. When damage to the electrolyte membrane 26 is detected, the control unit 24 controls the shutoff valve 66 to close the third flow path 64.
[0029] The catalyst device 68 includes, for example, a catalyst such as a precious metal (e.g., platinum). The catalyst converts a trace amount of oxygen mixed in the hydrogen into water and removes it by reacting hydrogen and oxygen. The oxygen mixed in the third flow path 64 comes from the first stack 16. That is, even in a state where the electrolyte membrane 26 is not damaged, the first stack 16 allows a trace amount of oxygen to pass through due to the pressure difference between the anode 26a and the cathode 26c. The oxygen that passes through the electrolyte membrane 26 is accumulated in the circulation path 21 of the hydrogen including the third flow path 64.
[0030] When a mixed gas with a high oxygen concentration is supplied to the catalyst device 68 due to damage to the electrolyte membrane 26, a violent reaction occurs in the catalyst device 68, and the temperature of the catalyst device 68 increases significantly due to the heat of the reaction. When the two conditions of an increase in the concentration of oxygen in the hydrogen gas and a high temperature of the catalyst device 68 are met, there is a concern that the hydrogen and oxygen constituting the mixed gas may damage the internal equipment of the electrochemical system 10. Therefore, the electrochemical system 10 of the present embodiment prevents the supply of the mixed gas to the catalyst device 68 by the exhaust device 56 and the shutoff valve 66 when damage to the electrolyte membrane 26 is detected.
[0031] In addition, the third flow path 64 may also include a pump for sending hydrogen into the hydrogen booster stack 18, but this is not particularly shown.
[0032] The hydrogen booster stack 18 is connected to the downstream end of the third flow path 64. The hydrogen booster stack 18 has a structure in which a plurality of single cells 32 are stacked. Each single cell 32 has an electrolyte membrane 28, and a cathode 28c and an anode 28a sandwiching the electrolyte membrane 28. The electrolyte membrane 28 of the hydrogen booster stack 18 of this embodiment is a proton transporter. + The electrolyte membrane 28 converts the hydrogen supplied to the anode 28a into protons H + The electrolyte membrane 28 allows the protons H to be + Move to cathode 28c. Proton H + The movement of protons H is carried out by overcoming the pressure difference on both sides of the electrolyte membrane 28. +The cathode 28c receives the electrons and releases them as hydrogen gas. The electrolyte membrane 28 thus causes the cathode 28c to generate hydrogen gas at a pressurized level.
[0033] The cathode 28c of the electrolyte membrane 28 communicates with the fourth flow path 70. The fourth flow path 70 connects the hydrogen booster stack 18 and the second tank 14. The hydrogen gas whose pressure is increased by the electrolyte membrane 28 passes through the fourth flow path 70 and is stored in the second tank 14.
[0034] On the other hand, the anode 28a of the electrolyte membrane 28 is supplied with hydrogen discharged from the gas-liquid separator 20 through the third flow path 64. The hydrogen is used for the electrochemical reaction of the anode 28a. The hydrogen not used in the electrochemical reaction returns to the gas-liquid separator 20 through the fifth flow path 72. The fifth flow path 72, together with the third flow path 64, forms a circulation path 21 for circulating hydrogen between the gas-liquid separator 20 and the anode 28a of the hydrogen booster stack 18.
[0035] The electrochemical system 10 of the present embodiment is configured as described above. Next, the operation of the electrochemical system 10 will be described.
[0036] like Figure 2 As shown, when the electrochemical system 10 starts electrolysis of water, it enters step S10 after the prescribed startup process. The control unit 24 supplies prescribed electric power to the first battery stack 16 and the hydrogen booster battery stack 18. Accordingly, the water electrolysis process is performed by the first battery stack 16, and the high-pressure oxygen is stored in the first tank 12, and the pressure is increased by the hydrogen booster battery stack 18, and the high-pressure hydrogen is stored in the second tank 14.
[0037] Next, in step S20 , the control unit 24 obtains a pressure difference ΔP (absolute value) obtained by subtracting the pressure detected by the first pressure sensor 52 from the pressure detected by the second pressure sensor 54 .
[0038] Next, in step S30, the control unit 24 determines whether the pressure difference ΔP is greater than a predetermined value. Figure 1 The first flow path 44 shown allows oxygen to flow in the positive direction of the check valve 50. In the positive flow, the pressure difference between the upstream and downstream of the check valve 50 is small, so the pressure difference ΔP is below the specified pressure. Therefore, when the pressure difference ΔP is below the specified pressure, the control unit 24 determines that the electrolyte membrane 26 is not damaged (No).
[0039] If the control unit 24 determines NO in step S30, the process proceeds to step S40. In step S40, the control unit 24 sets the timer to a predetermined value. The predetermined value of the timer set in step S40 reflects the waiting time for determining whether the electrolyte membrane 26 is damaged.
[0040] After this, the process proceeds to step S50. In step S50, the control unit 24 detects a determination (flag) indicating whether the electrolyte membrane 26 is damaged. In step S90 described later, a determination is made as to whether the electrolyte membrane 26 is damaged. In normal operation in which the value of the pressure difference ΔP is lower than a predetermined pressure, in step S50, the control unit 24 determines that there is no determination (No) that the electrolyte membrane 26 is damaged.
[0041] On the other hand, Figure 1 In the first battery stack 16, when the electrolyte membrane 26 is damaged, oxygen leaks from the high-pressure anode 26a to the low-pressure cathode 26c. Therefore, oxygen wants to flow in the first flow path 44 in the opposite direction, and the check valve 50 blocks the flow of oxygen in the first flow path 44. As a result, a large pressure difference ΔP is generated between the upstream and downstream of the check valve 50. When the value of the pressure difference ΔP exceeds the specified pressure of step S30, the control unit 24 determines as yes in step S30.
[0042] In step S30, when the control unit 24 determines that it is yes, in order to determine whether the detection result that the pressure difference ΔP exceeds the specified pressure continues for a specified waiting time, the processing is transferred to step S70. In step S70, the control unit 24 determines whether the value of the timer is 0. When the value of the timer is not 0 in step S70 (no), the control unit 24 determines that the specified waiting time has not passed and enters the processing into step S80. In step S80, the control unit 24 subtracts 1 from the value of the timer and transfers to step S50. Each time step S80 is passed, the value of the timer is subtracted by 1 from the specified value set in step S40. The processing of steps S70 and S80 is repeated until the value of the timer becomes 0. During this period, the electrochemical system 10 continues the electrolysis process.
[0043] On the other hand, in step S70, when the timer value is 0, the control unit 24 determines that the detection result exceeding the predetermined pressure continues for the predetermined waiting time (Yes), and the process proceeds to step S90. In step S90, the control unit 24 determines that the electrolyte membrane 26 is damaged. Thereafter, the process proceeds to step S50.
[0044] In addition, steps S70 to 80 are an example for preventing erroneous detection due to noise of the first pressure sensor 52 and the second pressure sensor 54, and the present embodiment is not limited to this example. When another method for preventing noise of the first pressure sensor 52 and the second pressure sensor 54 is adopted, steps S70 to 80 can be omitted.
[0045] When the control unit 24 determines that the electrolyte membrane 26 is damaged in the above-mentioned step S90 , the control unit 24 determines (Yes) in step S50 and advances the process to step S100 .
[0046] In step S100, the control unit 24 stops supplying electric power to the first fuel cell stack 16 and the hydrogen supercharged fuel cell stack 18. In step S110, the control unit 24 stops supplying electric power to the first fuel cell stack 16 and the hydrogen supercharged fuel cell stack 18. Figure 1 The shut-off valve 66 is closed to cut off the third flow path 64. By cutting off the third flow path 64, the mixed gas containing a large amount of oxygen is prevented from being supplied to the catalyst device 68. As a result, the electrochemical system 10 can prevent overheating of the catalyst device 68 and ignition of the mixed gas of hydrogen and oxygen. In addition, the shut-off valve 66 prevents oxygen from flowing into the hydrogen booster stack 18, thereby preventing the degradation of the catalyst (e.g., platinum) used for the electrode of the hydrogen booster stack 18.
[0047] After that, in step S120, the control unit 24 operates the exhaust device 56 to exhaust the mixed gas in the second flow path 46 and the gas-liquid separator 20. The exhaust device 56 reduces the concentration of the mixed gas in the second flow path 46 and the gas-liquid separator 20 to below the explosion range to prevent damage to the equipment.
[0048] In addition, the processes of steps S100 to S120 are not limited to the order shown in the figure, and may be performed in any order, or all the processes may be performed simultaneously.
[0049] On the other hand, in step S50, when the control unit 24 determines that there is no damage to the electrolyte membrane 26 (No), the control unit 24 causes the process to enter step S60. In step S60, the electrolysis process is continued. That is, electric power is continued to be supplied to the first battery stack 16 and the hydrogen booster battery stack 18. Thereafter, the process returns to step S20.
[0050] (Second embodiment)
[0051] Figure 3 The electrochemical system 10A of the present embodiment shown is a modified Figure 1 An example of the configuration of the catalyst device 68 of the electrochemical system 10 is shown. In addition, in the electrochemical system 10A ( Figure 3 ) is described with respect to the electrochemical system 10 ( Figure 1 ) The same structures are marked with the same figure symbols and their detailed descriptions are omitted.
[0052] In the electrochemical system 10A, the catalyst device 68 is connected to the downstream of the second flow path 46. The catalyst device 68 of the present embodiment is arranged so as to protrude into the gas-liquid separator 20. The catalyst device 68 is arranged at a position in contact with the water in the water storage portion 20w.
[0053] In addition, the electrochemical system 10A includes a heat exchanger 71 in the supply flow path 42. The heat exchanger 71 releases heat generated by the catalyst device 68 to the outside by lowering the temperature of water.
[0054] Such a catalyst device 68 can quickly release the heat generated when it contacts the mixed gas of oxygen and hydrogen into the water in the water storage unit 20w. Therefore, the electrochemical system 10A of this embodiment can suppress the temperature rise of the catalyst device 68, thereby preventing the catalyst device 68 from igniting the mixed gas of hydrogen and oxygen.
[0055] In addition, the heat exchanger 71 can prevent evaporation of water stored in the water storage portion 20 w of the gas-liquid separator 20 by lowering the temperature of water circulating between the gas-liquid separator 20 and the first cell stack 16 .
[0056] (Third embodiment)
[0057] Figure 4 The electrochemical system 10B shown is a Figure 1 A modified example of the electrochemical system 10 is provided with a pressure reducing regulator 76 capable of supplying hydrogen to the third flow path 64. In addition, in the electrochemical system 10B ( Figure 4 ) in the description of the electrochemical system 10 ( Figure 1 ) are marked with the same figure marks and their detailed description is omitted.
[0058] like Figure 4 As shown, the electrochemical system 10B has a pressure reduction adjustment unit 76. The pressure reduction adjustment unit 76 has a sixth flow path 78 and a seventh flow path 80. The sixth flow path 78 is a flow path connecting the fourth flow path 70 and the third flow path 64. One end of the sixth flow path 78 is connected to the fourth flow path 70 through a three-way valve 82, and the other end of the sixth flow path 78 is connected to the third flow path 64 downstream of the stop valve 66. A second stop valve 84 and a pressure reducing valve 86 are provided in the middle of the sixth flow path 78. The second stop valve 84 is opened and closed by the control unit 24. In the normal process of the electrochemical system 10B, the second stop valve 84 cuts off the flow of hydrogen gas in the sixth flow path 78. The second stop valve 84 opens the sixth flow path 78 when the control unit 24 detects damage to the electrolyte membrane 26. The pressure reducing valve 86 reduces the pressure of the high-pressure hydrogen gas flowing in the sixth flow path 78 and then supplies it to the third flow path 64.
[0059] The seventh flow path 80 is a flow path connecting the fifth flow path 72 and the third flow path 64. One end of the seventh flow path 80 is connected to the fifth flow path 72 via a three-way valve 88, and the other end of the seventh flow path 80 is connected to the third flow path 64 downstream of the stop valve 66. The seventh flow path 80 has a second check valve 90 in the middle. The second check valve 90 allows gas to flow only in the direction from the fifth flow path 72 to the third flow path 64.
[0060] In addition, Figure 4 In the third flow path 64, the catalyst device 68 is omitted (see Figure 1) is shown in the figure. In addition, a pump 92 for supplying hydrogen to the hydrogen booster stack 18 is provided in the third flow path 64.
[0061] The electrochemical system 10B of the present embodiment is configured as described above. Next, the operation of the electrochemical system 10B will be described.
[0062] In the electrochemical system 10B, when damage to the electrolyte membrane 26 of the first stack 16 is detected, the shutoff valve 66 of the third flow path 64 is closed, and the mixed gas containing hydrogen and oxygen is discharged from the gas-liquid separator 20 through the exhaust device 56. Figure 1 ) pressure drops rapidly. The rapid decompression of the anode 28a of the hydrogen-pressurized fuel cell 18 causes the water inside the electrolyte membrane 28 to boil violently, thereby causing damage to the electrolyte membrane 28 due to pores. Therefore, the hydrogen-pressurized fuel cell 18 is required to be gradually decompressed.
[0063] Therefore, the electrochemical system 10B of this embodiment starts the following actions when the shut-off valve 66 of the third flow path 64 is closed and exhaust begins through the exhaust device 56: the control unit 24 controls the pressure reduction adjustment unit 76 to supply hydrogen to the third flow path 64 through the sixth flow path 78 and the seventh flow path 80, thereby preventing rapid decompression of the anode 28a of the hydrogen booster stack 18.
[0064] When the stop valve 66 of the third flow path 64 is closed, the controller 24 rotates the three-way valve 82 of the sixth flow path 78 to connect the fourth flow path 70 and the sixth flow path 78, and opens the second stop valve 84. As a result, the hydrogen gas in the fourth flow path 70 is supplied to the third flow path 64 through the sixth flow path 78.
[0065] Furthermore, the control unit 24 rotates the three-way valve 88 of the seventh flow path 80 to connect the fifth flow path 72 and the seventh flow path 80 . As a result, the hydrogen gas in the fifth flow path 72 is supplied to the third flow path 64 through the seventh flow path 80 .
[0066] In this way, the electrochemical system 10B of this embodiment supplies hydrogen to the third flow path 64 through the sixth flow path 78 and the seventh flow path 80 after the shut-off valve 66 of the third flow path 64 is closed, thereby preventing the pressure of the anode 28a of the hydrogen pressurized stack 18 from dropping rapidly.
[0067] (Fourth embodiment)
[0068] Figure 5The electrochemical system 10C of the present embodiment shown has a hydrogen booster stack 18 as the first stack 16D. The hydrogen booster stack 18 has an electrolyte membrane 28 that electrochemically boosts the pressure of the hydrogen gas flowing in. The hydrogen booster stack 18 is connected to the first tank 12 via a first flow path 44. The first flow path 44 has a check valve 50, a first pressure sensor 52 connected upstream of the check valve 50, and a second pressure sensor 54 connected downstream of the check valve 50.
[0069] The unreacted hydrogen gas is discharged as the second gas from the first cell stack 16D through the second flow path 46. That is, in the present embodiment, both the first gas and the second gas are hydrogen gas.
[0070] The control unit 24 determines whether the electrolyte membrane 28 of the first stack 16D is damaged based on the pressure difference ΔP between the first pressure sensor 52 and the second pressure sensor 54. When the control unit 24 determines that the electrolyte membrane 28 is damaged, it operates a stop valve or exhaust device (not shown) connected to the second flow path 46, thereby preventing a malfunction caused by leakage of hydrogen.
[0071] The above disclosed contents are summarized as follows.
[0072] An electrochemical system 10, 10A to 10C of one embodiment comprises a first battery stack 16, 16D, a first storage tank 12, a check valve 50, a first pressure sensor 52, a second pressure sensor 54 and a control unit 24, wherein the first battery stack 16, 16D comprises a membrane electrode assembly 27 in which an electrolyte membrane 26 is clamped by a first electrode 26a and a second electrode 26c; the first storage tank 12 stores a high-pressure first gas output by the first battery stack; the check valve 50 is arranged at a position connecting the first battery stack and the first storage tank The flow path 44; the first pressure sensor 52 is connected to the flow path upstream of the check valve; the second pressure sensor 54 is connected to the flow path downstream of the check valve; the control unit 24 detects whether the electrolyte membrane is damaged based on the detection pressures of the first pressure sensor and the second pressure sensor, and the control unit determines that the electrolyte membrane is damaged when the pressure difference ΔP obtained by subtracting the detection pressure of the first pressure sensor from the detection pressure of the second pressure sensor exceeds a specified pressure.
[0073] The electrochemical system described above prevents malfunctions due to leakage of the first gas by determining whether the electrolyte membrane is damaged based on the pressure difference between the upstream and downstream of the check valve in the first flow path.
[0074] In the above-mentioned electrochemical system, there may be an exhaust device 56, which can exhaust the second gas exhausted from the first battery stack to the outside, and when it is determined that the electrolyte membrane is damaged, the control unit controls the exhaust device to exhaust the second gas. This electrochemical system can prevent malfunctions caused by a mixed gas of the first gas and the second gas by exhausting the leaked first gas together with the second gas.
[0075] In the above-mentioned electrochemical system, the first stack may be a water electrolysis stack 17 that generates oxygen as the first gas and hydrogen as the second gas by electrolyzing supplied water, and the electrochemical system has a gas-liquid separator 20 that separates the water supplied to the first stack from the hydrogen output from the first stack. The electrochemical system can prevent malfunctions caused by a mixed gas of hydrogen and oxygen.
[0076] In the electrochemical system described above, the exhaust device may be provided in the gas-liquid separator. Since the electrochemical system can exhaust only the gas, the loss of water can be suppressed.
[0077] In the above-mentioned electrochemical system, it can also be provided with a hydrogen supercharged stack 18 and a shutoff valve 66, wherein the hydrogen supercharged stack 18 pressurizes the hydrogen separated from water by the gas-liquid separator; the shutoff valve 66 cuts off the supply of hydrogen from the gas-liquid separator to the hydrogen supercharged stack, and when it is determined that the electrolyte membrane is damaged, the control unit controls the shutoff valve to cut off the supply of hydrogen from the gas-liquid separator to the hydrogen supercharged stack. The electrochemical system can prevent the mixed gas of hydrogen and oxygen from flowing into the hydrogen supercharged stack, thereby preventing the degradation of the catalyst of the hydrogen supercharged stack.
[0078] In the above-mentioned electrochemical system, the shutoff valve may be provided in a third flow path 64 connected to the gas-liquid separator and the hydrogen booster stack.
[0079] The electrochemical system may include a catalyst device 68 for removing oxygen from the hydrogen supplied from the first stack to the hydrogen boost stack by a catalytic reaction. The electrochemical system can prevent the mixed gas of hydrogen and oxygen from igniting due to the catalyst device.
[0080] In the above electrochemical system, the shutoff valve may be provided in a third flow path connected to the gas-liquid separator and the hydrogen booster stack, and the catalyst device may be provided downstream of the shutoff valve in the third flow path. The electrochemical system can prevent the mixed gas of hydrogen and oxygen from flowing into the catalyst device through the shutoff valve.
[0081] In the electrochemical system, the catalyst device may be disposed at a location in contact with water stored in the gas-liquid separator. The electrochemical system prevents ignition of the mixed gas of hydrogen and oxygen by releasing heat generated by the catalyst device into water.
[0082] In the above-mentioned electrochemical system, there may also be a decompression adjustment unit 76, which returns the hydrogen gas output from the hydrogen supercharged stack and pressurized to the hydrogen supercharged stack, and when it is determined that the electrolyte membrane is damaged, the control unit controls the decompression adjustment unit to return the hydrogen gas to the hydrogen supercharged stack. The electrochemical system prevents the hydrogen supercharged stack from being rapidly decompressed due to the operation of the exhaust device or the closure of the stop valve, thereby preventing damage to the electrolyte membrane.
[0083] In addition, the present invention is not limited to the above-mentioned disclosure, and various structures can be adopted within the scope not departing from the gist of the present invention.
Claims
1. An electrochemical system (10, 10A, 10B, 10C), characterized in that: The invention comprises a first battery stack (16, 16D), a first storage tank (12), a check valve (50), a first pressure sensor (52), a second pressure sensor (54) and a control unit (24), wherein: The first cell stack (16, 16D) comprises a membrane electrode assembly (27) in which an electrolyte membrane (26) is sandwiched between a first electrode (26a) and a second electrode (26c); The first storage tank (12) stores the high-pressure first gas output by the first fuel cell stack; The check valve (50) is arranged in a flow path (44) connecting the first fuel cell stack and the first storage tank; The first pressure sensor (52) is connected to the flow path upstream of the check valve; The second pressure sensor (54) is connected to the flow path downstream of the check valve; The control unit (24) determines whether the electrolyte membrane is damaged based on the pressure detected by the first pressure sensor and the second pressure sensor. The control unit determines that the electrolyte membrane is damaged when a differential pressure obtained by subtracting the pressure detected by the first pressure sensor from the pressure detected by the second pressure sensor exceeds a predetermined pressure.
2. The electrochemical system according to claim 1, characterized in that An exhaust device (56) is provided, wherein the exhaust device (56) is capable of exhausting the second gas exhausted from the first fuel cell stack to the outside. When it is determined that the electrolyte membrane is damaged, the control unit controls the exhaust device to exhaust the second gas.
3. The electrochemical system according to claim 2, characterized in that The first cell stack is a water electrolysis stack (17) that generates oxygen as the first gas and hydrogen as the second gas by electrolyzing supplied water. The electrochemical system includes a gas-liquid separator (20) for separating water supplied to the first cell stack from hydrogen exhausted from the first cell stack.
4. The electrochemical system according to claim 3, characterized in that The exhaust device is provided in the gas-liquid separator.
5. The electrochemical system according to claim 3, characterized in that A hydrogen pressurized fuel cell stack (18) and a shut-off valve (66) are provided, wherein: The hydrogen booster stack (18) boosts the pressure of the hydrogen separated from the water by the gas-liquid separator. The shutoff valve (66) cuts off the supply of hydrogen from the gas-liquid separator to the hydrogen booster stack. When it is determined that the electrolyte membrane is damaged, the control unit controls the shutoff valve to cut off the supply of hydrogen from the gas-liquid separator to the hydrogen boost stack.
6. The electrochemical system according to claim 5, characterized in that The shutoff valve is provided in a third flow path (64), and the third flow path (64) is connected to the gas-liquid separator and the hydrogen booster stack.
7. The electrochemical system according to claim 5, characterized in that A catalyst device (68) is provided, and the catalyst device (68) removes oxygen from the hydrogen supplied from the first fuel cell stack to the hydrogen boost fuel cell stack through a catalytic reaction.
8. The electrochemical system according to claim 7, characterized in that The shutoff valve is provided in a third flow path connected to the gas-liquid separator and the hydrogen booster stack, and the catalyst device is provided downstream of the shutoff valve in the third flow path.
9. The electrochemical system according to claim 7, characterized in that: The catalyst device is disposed at a location in contact with water stored in the gas-liquid separator.
10. The electrochemical system according to claim 5, characterized in that A pressure reducing regulator (76) is provided, wherein the pressure reducing regulator (76) returns the hydrogen gas output from the hydrogen boosting stack and pressurized to the hydrogen boosting stack. When it is determined that the electrolyte membrane is damaged, the control unit controls the pressure reduction adjustment unit to return the hydrogen to the hydrogen boost stack.