A PEM water electrolysis hydrogen production system and control method

Abstract

This invention discloses a PEM (Polymer Electrolysis) water electrolysis hydrogen production system and control method, belonging to the field of electrolysis hydrogen production technology. The PEM water electrolysis hydrogen production system provided by this invention includes a pure water machine, a temperature-controlled water tank, a circulating water tank, a heat exchanger, an electrolyzer, a first vapor-water separator, and a control system. A three-way valve and a first water pump are installed on the pipeline between the circulating water tank and the heat exchanger. The outlet of the electrolyzer is connected to the inlet of the circulating water tank and the first vapor-water separator via pipelines. The outlet of the first vapor-water separator is connected to the circulating water tank via a pipeline. The outlet of the circulating water tank, the first water pump, and the outlet of the first vapor-water separator are connected to the three-way valve. The control system is used to control the opening and closing of the first and second solenoid valves, the valve opening degree of the three-way valve, the speed of the first water pump, and the current of the electrolyzer. This invention enables rapid system startup while avoiding the risk of electrolyzer damage caused by high-current startup.

Description

Technical Field

[0001] This invention relates to the field of hydrogen electrolysis technology, and in particular to a PEM water electrolysis hydrogen production system and control method. Background Technology

[0002] The information disclosed in the background of the invention is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Proton exchange membrane (PEM) water electrolysis for hydrogen production is a core direction in green hydrogen production. With its advantages of fast response, high current density, and pure gas production, it is widely used in renewable energy-coupled hydrogen production and industrial hydrogen supply scenarios. However, the operational stability and energy efficiency optimization of PEM water electrolysis systems remain the main bottlenecks for its large-scale promotion.

[0004] During startup, a PEM water electrolysis hydrogen production system must simultaneously meet the requirements of reaching the specified inlet temperature of the electrolyzer and raising the current to the set value to complete startup. However, in existing technologies, this process is often time-consuming: firstly, the large volume of water in the circulating tank requires gradual heating as it flows through the electrolyzer, and the large water volume and its heat capacity result in a slow temperature rise; secondly, to meet the heat dissipation requirements of the electrolyzer and avoid damage to the precision components of the electrolyzer from high current surges at low temperatures, the system typically adopts a low-current startup mode, which generates less heat and further slows down the heating rate. These two factors combined significantly extend the startup cycle. Therefore, it is necessary to provide a PEM water electrolysis hydrogen production system that can start up quickly and operate stably. Summary of the Invention

[0005] In view of this, the present invention provides a PEM electrolysis water hydrogen production system and control method. The PEM electrolysis water hydrogen production system provided by the present invention can achieve rapid start-up and significantly shorten the start-up cycle.

[0006] In a first aspect, the present invention provides a PEM water electrolysis hydrogen production system, including a pure water machine, a temperature-controlled water tank, a circulating water tank, a heat exchanger, an electrolyzer, a first gas-water separator, and a control system;

[0007] The pure water machine, temperature-controlled water tank, circulating water tank, heat exchanger, and electrolytic cell are connected in series via pipelines; a three-way valve and a first water pump are installed on the pipeline between the circulating water tank and the heat exchanger.

[0008] The outlet of the electrolytic cell is connected to the circulating water tank through a pipeline equipped with a first solenoid valve; the outlet of the electrolytic cell is connected to the inlet of the first steam-water separator through a pipeline equipped with a second solenoid valve; the outlet of the first steam-water separator is connected to the circulating water tank through a pipeline.

[0009] The outlet of the circulating water tank, the outlet of the first water pump, and the outlet of the first steam-water separator are connected to a three-way valve;

[0010] The control system is used to control the opening and closing of the first and second solenoid valves, the valve opening degree of the three-way valve, the speed of the first water pump, and the current of the electrolytic cell.

[0011] Preferably, a third solenoid valve is installed on the pipeline between the water purifier and the temperature-controlled water tank, and a fourth solenoid valve is installed on the pipeline between the temperature-controlled water tank and the circulating water tank; the temperature-controlled water tank is equipped with a heating module, and the heating module is electrically connected to the control system.

[0012] Preferably, it also includes a temperature acquisition unit, a liquid level acquisition unit, and a flow rate acquisition unit. The temperature acquisition unit is used to acquire the temperature values ​​of the temperature-controlled water tank, the circulating water tank, the electrolytic cell inlet, and the electrolytic cell outlet. The liquid level acquisition unit is used to acquire the liquid levels of the temperature-controlled water tank and the circulating water tank. The flow rate acquisition unit is used to acquire the flow rate of the electrolytic cell inlet.

[0013] Preferably, it also includes a chiller, which is circulated with the heat exchanger through a first pipeline and a second pipeline; the second pipeline is equipped with an electrically operated valve.

[0014] Furthermore, it also includes a heat recovery system, which is connected to the first pipeline via a third pipeline, and a third solenoid valve is installed on the third pipeline; the heat recovery system is connected to the second pipeline between the electric opening valve and the heat exchanger via a fourth pipeline; a second water pump is installed on the fourth pipeline.

[0015] Preferably, it also includes a second steam-water separator, a condenser, and a hydrogen purification system; the second steam-water separator is connected to the outlet of the electrolytic cell, the outlet of the second steam-water separator is connected to the condenser, and the condenser is connected to the hydrogen purification system.

[0016] Furthermore, the liquid outlet of the second steam-water separator and the condenser is connected to the liquid sealing device through a fifth pipeline, and the liquid sealing device is connected to the temperature-controlled water tank; a pressure buffer tank is installed on the fifth pipeline.

[0017] Preferably, it also includes an oxygen treatment system, which is connected to the circulating water tank.

[0018] Secondly, the present invention provides a control method for the above-mentioned PEM water electrolysis hydrogen production system, comprising the following steps:

[0019] When the PEM water electrolysis hydrogen production system is started, water in the circulating water tank enters the electrolyzer through the three-way valve. When the water flow reaches the idle flow rate, the first solenoid valve is closed, the second solenoid valve is opened, and the valve opening of the three-way valve is adjusted so that the liquid output of the circulating water tank is 0. The current of the electrolyzer is gradually increased according to the measured value of the inlet temperature of the electrolyzer, and the speed of the first water pump is adjusted according to the current value until the rated current is reached.

[0020] Once the inlet temperature of the electrolytic cell is greater than or equal to the target temperature, open the first solenoid valve and control the opening of the three-way valve to gradually increase the liquid output of the circulating water tank and gradually decrease the liquid output of the first steam-water separator, thereby controlling the inlet temperature of the electrolytic cell to remain constant until the liquid output of the first steam-water separator is 0. Then close the second solenoid valve to reach the stable operation stage.

[0021] Preferably, when the PEM water electrolysis hydrogen production system is started, the method further includes adjusting the temperature of the temperature-controlled water tank to reach the preset temperature value and controlling the root mean square error of the temperature in the temperature-controlled water tank to be less than the preset value; monitoring the liquid level of the circulating water tank, and controlling the temperature-controlled water tank to replenish water when the measured liquid level is lower than the preset liquid level value.

[0022] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0023] (1) The PEM water electrolysis hydrogen production system provided by the present invention achieves flexible adjustment of the circulating water flow and path by dynamically switching the pipeline through the three-way valve, the first solenoid valve and the second solenoid valve. When starting up, the branch circulation of "first steam-water separator - three-way valve - first water pump - heat exchanger - electrolytic cell - second solenoid valve - first steam-water separator" ensures rapid temperature rise. At the same time, the current value of the electrolytic cell is gradually increased by the control system, which can realize rapid system start-up. It overcomes the disadvantages of starting with small current and slow heating speed and long start-up cycle when heating large volume water in the prior art, and also avoids the risk of electrolytic cell damage caused by high current start-up.

[0024] (2) The present invention uses the control system to control the opening and closing of the first / second solenoid valve, the opening degree of the three-way valve, the speed of the first water pump and the current of the electrolytic cell, etc., and combines the real-time monitoring data of the temperature acquisition unit, the liquid level acquisition unit and the flow acquisition unit to form a closed-loop regulation mechanism, which can dynamically adjust the operating status according to parameters such as temperature, flow rate and liquid level.

[0025] (3) The present invention further optimizes the heat management capability of the system through the temperature-controlled water tank heating module, the chiller (with electric opening valve) and the heat recovery system: the temperature-controlled water tank can pre-adjust the water temperature through the heating module to reduce the impact of low temperature water replenishment on the temperature of the electrolytic cell; the circulation connection between the chiller and the heat exchanger can adjust the heat dissipation efficiency and avoid energy waste caused by excessive heat dissipation under rated power; the heat recovery system can recover redundant heat for other processes or the system itself through the connection design of the third and fourth pipelines, reduce operating energy consumption and achieve energy efficiency optimization. Attached Figure Description

[0026] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0027] Figure 1 This is a schematic diagram of the PEM electrolysis water production system of Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the control method for rapid startup of the PEM electrolysis water hydrogen production system according to Embodiment 2 of the present invention;

[0029] Figure 3 This is a schematic diagram of the control method for the water replenishment process of the PEM electrolysis water hydrogen production system in Embodiment 2 of the present invention;

[0030] Figure 4 This is a schematic diagram of the control method for the heat recovery process of the PEM electrolysis water hydrogen production system in Embodiment 2 of the present invention;

[0031] In the diagram, 1. Pure water machine; 2. Temperature-controlled water tank; 3. Circulating water tank; 4. Heat exchanger; 5. Electrolytic cell; 6. First steam-water separator; 7. Chiller; 8. Heat recovery system; 9. Three-way valve; 10. First water pump; 11. First temperature sensor; 12. Second temperature sensor; 13. Third temperature sensor; 14. Fourth temperature sensor; 15. Fifth temperature sensor; 16. First liquid level sensor; 17. Second liquid level sensor; 18. Flow sensor; 19. 20. First solenoid valve; 21. Second solenoid valve; 22. Third solenoid valve; 23. Fourth solenoid valve; 24. Heating module; 25. Oxygen treatment system; 26. First pipeline; 27. Second pipeline; 28. Fifth solenoid valve; 29. ​​Third pipeline; 30. Fourth pipeline; 31. Second water pump; 32. Second steam-water separator; 33. Condenser; 34. Hydrogen purification system; 35. Liquid sealing device; 36. Fifth pipeline; 37. Pressure buffer tank; 38. Electric opening valve. Detailed Implementation

[0032] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0033] Example 1

[0034] This embodiment provides a PEM water electrolysis hydrogen production system, such as Figure 1 As shown, the system includes a pure water machine 1, a temperature-controlled water tank 2, a circulating water tank 3, a heat exchanger 4, an electrolytic cell 5, a first steam-water separator 6, a chiller 7, a heat recovery system 8, and a control system. It also includes a temperature acquisition unit, a liquid level acquisition unit, and a flow rate acquisition unit. The pure water machine 1, temperature-controlled water tank 2, circulating water tank 3, heat exchanger 4, and electrolytic cell 5 are connected in series via pipelines. A three-way valve 9 and a first water pump 10 are installed on the pipeline between the circulating water tank 3 and the heat exchanger 4.

[0035] The temperature acquisition unit includes a first temperature sensor 11, a second temperature sensor 12, a third temperature sensor 13, a fourth temperature sensor 14, and a fifth temperature sensor 15, which are used to acquire the temperature values ​​of the temperature-controlled water tank 2, the circulating water tank 3, the inlet of the electrolytic cell 5, the outlet of the electrolytic cell 5, and the heat recovery system 8, respectively. The liquid level acquisition unit includes a first liquid level sensor 16 and a second liquid level sensor 17, which are used to acquire the liquid levels of the temperature-controlled water tank 2 and the circulating water tank 3, respectively. The flow rate acquisition unit includes a flow sensor 18, which is used to acquire the inlet flow rate of the electrolytic cell 5.

[0036] A third solenoid valve 21 is installed on the pipeline between the water purifier 1 and the temperature-controlled water tank 2 to control the flow of purified water from the water purifier 1 to the temperature-controlled water tank 2. A fourth solenoid valve 22 is installed on the pipeline between the temperature-controlled water tank 2 and the circulating water tank 3 to control the flow of water from the temperature-controlled water tank 2 into the circulating water tank 3. The temperature-controlled water tank 2 is equipped with a heating module 23, which is electrically connected to the control system. This electrical connection is used to determine whether heating is needed based on the measured temperature value of the temperature-controlled water tank 2, thereby ensuring that the water in the temperature-controlled water tank 2 maintains a constant temperature during stable operation.

[0037] Since the water supply temperature output by the pure water machine 1 is usually much lower than the optimal operating temperature range of the electrolyzer 5, the low-temperature water, when directly injected into the circulation system, will mix with the medium and lower the inlet temperature of the electrolyzer 5, causing fluctuations in the internal reaction environment. Frequent fluctuations will exacerbate the difference in thermal stress between the membrane electrode and the diffusion layer, accelerating material aging and shortening the lifespan of the electrolyzer 5 over long-term operation. Therefore, this invention includes a temperature-controlled water tank 2 between the pure water machine 1 and the circulating water tank 3 to ensure that the temperature does not fluctuate during water replenishment when the electrolyzer 5 is operating stably, thus avoiding adverse effects on the electrolyzer 5.

[0038] The outlet of the electrolytic cell 5 is connected to the circulating water tank 3 via a pipeline equipped with a first solenoid valve 19. The liquid flowing from the outlet of the electrolytic cell 5 is a mixture of oxygen and water, which flows directly into the circulating water tank 3 through the pipeline containing the first solenoid valve 19. The water can be recycled, while the oxygen enters the oxygen treatment system 24 for processing. The oxygen treatment system 24 is connected to the circulating water tank 3. When the first solenoid valve 19 is closed, this pipeline is blocked, meaning the mixture flowing from the outlet of the electrolytic cell 5 does not flow directly into the circulating water tank 3.

[0039] The outlet of the electrolytic cell 5 is connected to the inlet of the first steam-water separator 6 via a pipeline equipped with a second solenoid valve 20; the outlet of the first steam-water separator 6 is connected to the circulating water tank 3 via a pipeline. The first steam-water separator 6 separates oxygen and water in the effluent from the electrolytic cell 5. The separated oxygen enters the circulating water tank 3 through the outlet, and then enters the oxygen treatment system 24 for treatment; the separated water is connected to the three-way valve 9 through the outlet. Since the electrolytic cell 5 continuously produces oxygen during operation, the design of the first steam-water separator 6 minimizes the adverse effects of oxygen on the pipeline "first steam-water separator 6 - three-way valve 9 - first water pump 10 - heat exchanger 4 - electrolytic cell 5", such as preventing pipeline damage due to increased gas pressure.

[0040] The outlets of the circulating water tank 3, the first water pump 10, and the first steam-water separator 6 are connected to a three-way valve 9. Specifically, the water flowing out of the outlets of the circulating water tank 3 and the first steam-water separator 6 enters the three-way valve 9, and after flowing out through the three-way valve 9, it enters the first water pump 10. The ratio of the output volume of the circulating water tank 3 to the output volume of the first steam-water separator 6 can be controlled according to the opening degree of the three-way valve 9. In the prior art, the circulating water tank 3 is usually only connected to the electrolytic cell 5. Because the water volume in the circulating water tank 3 is large when the electrolytic cell 5 is heated, the time required for the electrolytic cell 5 to reach the target temperature is relatively long. This invention utilizes the continuous self-heating of the electrolytic cell 5 during startup, along with a small-volume branch circulation of "first steam-water separator 6 - three-way valve 9 - first water pump 10 - heat exchanger 4 - electrolytic cell 5 - second solenoid valve 20 - first steam-water separator 6," to rapidly raise the water temperature entering the electrolytic cell 5 to the target temperature, thus completing the heating process. Since the electrolytic cell 5 continuously generates heat during operation, the water temperature in the branch circulation may exceed the target temperature. Therefore, by adjusting the three-way valve 9, the output of the circulating water tank 3 can be gradually increased, while the output of the first steam-water separator 6 can be gradually decreased until it reaches zero. This ensures that during stable operation, only the main circulation loop of "circulating water tank 3 - three-way valve 9 - first water pump 10 - heat exchanger 4 - electrolytic cell 5 - first solenoid valve 19 - circulating water tank 3" is maintained.

[0041] The control system is used to control the opening and closing of the first solenoid valve 19 and the second solenoid valve 20, the valve opening degree of the three-way valve 9, the speed of the first water pump 10, and the current of the electrolytic cell 5. The control system is further preferably a PID controller.

[0042] Even after the system reaches its rated power and the temperature of the circulating water tank 3 matches the outlet temperature of the electrolytic cell 5, the heat generated by the electrolytic cell 5 continues to increase, thus requiring high heat dissipation. Traditional designs typically use heat exchangers for heat dissipation, but this doesn't fully utilize the heat. In this invention, the chiller 7 is circulated with the heat exchanger 4 via a first pipe 25 and a second pipe 26; an electrically operated valve 37 is installed on the second pipe 26. The heat recovery system 8 is connected to the first pipe 25 via a third pipe 28, which is equipped with a fifth solenoid valve 27; the heat recovery system 8 is also connected to the second pipe 26 between the electrically operated valve 37 and the heat exchanger 4 via a fourth pipe 29; a second water pump 30 is installed on the fourth pipe 29. When the temperature of the heat recovery system 8 is lower than the inlet temperature of the electrolytic cell 5, the chiller 7 is switched to standby mode, the electrically operated valve 37 is closed, and the water in the heat recovery system 8 is connected to the heat exchanger 4, thereby reducing the inlet temperature of the electrolytic cell 5 and recovering heat. When the temperature of the heat recovery system 8 is above the inlet temperature of the electrolytic cell 5, the second water pump 30 and the fifth solenoid valve 27 are turned off, the chiller 7 is started, the electric opening valve 37 is adjusted, and the chiller 7 is used to cool and dissipate heat from the inlet of the electrolytic cell 5.

[0043] The PEM electrolysis water hydrogen production system of the present invention further includes a second steam-water separator 31, a condenser 32, and a hydrogen purification system 33. The second steam-water separator 31 is connected to the outlet of the electrolyzer 5, and preliminary separation of hydrogen and water is achieved through the second steam-water separator 31. The outlet of the second steam-water separator 31 is connected to the condenser 32, and the condenser 32 is connected to the hydrogen purification system 33. The condenser 32 further removes moisture from the inlet gas, and then the hydrogen enters the hydrogen purification system 33. The cooling medium of the condenser 32 is provided by a chiller 7.

[0044] The liquid outlet of the second steam-water separator 31 and the liquid outlet of the condenser 32 are connected to the liquid sealing device 34 via a fifth pipeline 35. The liquid sealing device 34 is connected to the temperature-controlled water tank 2. A pressure buffer tank 36 is installed on the fifth pipeline 35. The separated water and the condensed water are recycled. Since there is still residual hydrogen in the separated water, a pressure buffer tank 36 is installed in the fifth pipeline 35 to prevent excessive pressure from adversely affecting the fifth pipeline 35. The liquid sealing device 34 allows water to flow into the temperature-controlled water tank 2, while the residual hydrogen is discharged.

[0045] Example 2

[0046] This embodiment provides a control method for the PEM water electrolysis hydrogen production system of Example 1.

[0047] like Figure 2 As shown, during startup, the system first checks whether the value of the flow sensor 18 is greater than or equal to the idle flow rate. The idle flow rate refers to the minimum water flow threshold set during the startup phase or low-load operation of the PEM water electrolysis hydrogen production system to maintain basic water circulation inside the electrolyzer 5 and prevent dry burning or local overheating. If this condition is met, the first solenoid valve 19 is closed, the second solenoid valve 20 is opened, and the opening of the three-way valve 9 is adjusted to make the liquid output of the circulating water tank 3 zero. If this condition is not met, water is continuously replenished through the circulating water tank 3 until the above condition is met. At this time, water continuously circulates in the branch "first steam-water separator 6 - three-way valve 9 - heat exchanger 4 - electrolyzer 5 - second solenoid valve 20 - first steam-water separator 6". The electrolyzer 5 is started with a small current. As the electrolyzer 5 operates, the inlet temperature of the electrolyzer 5 (represented by TE003) continuously increases. The current value is gradually increased according to the inlet temperature value of the electrolyzer 5, and the speed of the first water pump 10 is adjusted according to the current value until the rated current is reached. Specifically:

[0048] When T1 < TE003 ≤ T2, the current is drawn up to 30% of the rated current; when T2 < TE003 ≤ T3, the current is drawn up to 50% of the rated current; when T3 < TE003 ≤ T4, the current is drawn up to 75% of the rated current; when T4 < TE003 ≤ the target temperature at the inlet of electrolytic cell 5, the current is drawn up to the rated current.

[0049] Based on the law of conservation of energy, establish the temperature model formula for electrolytic cell 5, and input the actual operating current I of the power supply. el and the measured single-chamber voltage U cell Electrolytic cell 5 outlet temperature T out, PEM Electrolytic cell 5 inlet temperature T in, PEM The required liquid flow rate through the electrolytic cell 5 is calculated, and the calculated liquid flow rate is used to send a speed signal to the first water pump 10, thereby adjusting the actual liquid flow rate in the pipeline.

[0050] The temperature model formula for electrolytic cell 5 is as follows:

[0051] .

[0052] In the formula, U cell Measured voltage of individual chamber 5 in electrolytic cell, unit: V; I el Total DC current of electrolytic cell 5, in A; n cell Number of single-cell electrolytic cells: 5; V th The theoretical voltage of a single cell in electrolytic cell 5, in V; T in, PEM Inlet temperature of electrolytic cell 5, in K; T out, PEM The outlet temperature of electrolytic cell 5, in K; Tstack Temperature 5 of the electrolytic cell, in K; C stack The specific heat capacity of the electrolytic cell is 5 kJ / kg. -1 ·K -1 ;q cl Liquid flow rate requirement, in kg·s -1 C cl Specific heat capacity of a liquid, expressed in K·kg -1 ·K -1 Q gas The amount of heat dissipated by the electrolytic cell 5 through air convection is determined by empirical data.

[0053] For the first water pump 10, a linear function relationship between rotational speed and flow rate is established, based on the liquid flow rate demand. The actual speed and power of the water pump are obtained through flow-speed-power diagram analysis. The actual speed signal is then sent to the controller of the first water pump 10 for real-time adjustment of the actual speed of the first water pump 10 to meet the liquid flow requirements under different currents and ensure the normal operation of the electrolytic cell 5. The formula is as follows:

[0054] .

[0055] In the formula, n w,0 The first water pump has a rated speed of 10 rpm; q w,0 The rated flow rate of the first water pump is 10 L·min. -1 ;n w,1 The actual rotational speed of the first water pump is 10 rpm; q w,1 The actual flow rate of the first water pump is 10, in L·min. -1 .

[0056] Once the inlet temperature of electrolytic cell 5 is greater than or equal to the target inlet temperature, the temperature in the branch circulation has reached the target inlet temperature of electrolytic cell 5. However, the circulating water tank 3 is still cold water. As the temperature of electrolytic cell 5 continues to increase during operation, the first solenoid valve 19 is opened, and the opening degree of the three-way valve 9 is controlled, causing the liquid output from the circulating water tank 3 to gradually increase, while the liquid output from the first steam-water separator 6 gradually decreases. The cold water in the circulating water tank 3 mixes with the hot water in the branch circulation and flows into the electrolytic cell 5. The inlet temperature of the electrolytic cell 5 is kept constant by controlling the valve opening. The effluent from the electrolytic cell 5 can directly enter the circulating water tank 3, thereby causing the temperature of the circulating water tank 3 to continuously rise until the liquid output from the first steam-water separator 6 reaches 0. At this point, the second solenoid valve 20 is closed, reaching the stable operation stage.

[0057] When the PEM water electrolysis hydrogen production system starts up, it also includes adjusting the temperature of the temperature-controlled water tank 2 to reach the preset temperature value and controlling the root mean square error (RMSE) of the temperature in the temperature-controlled water tank 2 to be less than the preset value. The RMSE value is collected at a frequency of 1Hz, and the temperature of the temperature-controlled water tank 2 is continuously collected for 5 seconds. During startup and stable operation, the liquid level of the circulating water tank 3 is continuously monitored. When the measured liquid level is lower than the preset liquid level value, the temperature-controlled water tank 2 is controlled to replenish water. The water replenishment strategy is as follows: Figure 3 As shown, the details are as follows:

[0058] The system determines whether the liquid level LS001 of the temperature-controlled water tank 2 meets the following conditions: first preset value ≤ LS001 ≤ second preset value. If not, when LS001 is less than the first preset value, the third solenoid valve 21 is opened; when LS001 is greater than the second preset value, the third solenoid valve 21 is closed. If met, the system determines whether the liquid level LS002 of the circulating water tank 3 meets the following conditions: third preset value ≤ LS002 ≤ fourth preset value. If not, when LS002 is less than the third preset value, the fourth solenoid valve 22 is opened; when LS002 is greater than the fourth preset value, the fourth solenoid valve 22 is closed. If met, the system determines whether the RMSE value of the temperature-controlled water tank 2 is greater than or equal to the preset value. If yes, the system adjusts the power of the heating module 23 of the temperature-controlled water tank 2 until the RMSE value is less than the preset value. If no, the system turns off the heating module 23.

[0059] The formula for calculating the RMSE value of temperature is as follows:

[0060] .

[0061] In the formula, n is the number of samples, and T 实测 This represents the measured temperature value of temperature-controlled water tank 2, T. 目标 This represents the temperature value of the target temperature-controlled water tank 2.

[0062] Control methods for heat recovery processes, such as Figure 4 As shown. When the temperature value TE005 of the heat recovery system 8 is detected to be less than the inlet temperature TE003 of the electrolytic cell 5, the refrigeration system is shut down, i.e., the electric valve 37 is closed; the heat recovery system 8 is activated, i.e., the fifth solenoid valve 27 is opened, and the inlet temperature TE003 of the electrolytic cell 5 is controlled in real time by adjusting the speed of the second water pump 30, so that TE003 reaches the target inlet temperature of the electrolytic cell 5. When the temperature value TE005 of the heat recovery system 8 is detected to be greater than or equal to the inlet temperature TE003 of the electrolytic cell 5, the heat recovery system 8 is shut down, i.e., the fifth solenoid valve 27 is closed; the refrigeration system is activated, i.e., the electric valve 37 is opened, and the inlet temperature TE003 of the electrolytic cell 5 is adjusted by adjusting the chilled water outlet temperature of the chiller 7 and the opening degree of the electric valve 37, so that TE003 reaches the target inlet temperature of the electrolytic cell 5. The above control method can achieve waste heat recovery and reuse under the premise of stable control of the inlet temperature of the electrolytic cell 5.

[0063] The PEM water electrolysis hydrogen production system provided by this invention has the functions of rapid start-up, automatic water replenishment and temperature control, and waste heat recovery, which can achieve the best performance of the electrolyzer and extend the service life of the system.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A PEM water electrolysis hydrogen production system, characterized in that, It includes a pure water machine, a temperature-controlled water tank, a circulating water tank, a heat exchanger, an electrolytic cell, a first steam-water separator, and a control system; The pure water machine, temperature-controlled water tank, circulating water tank, heat exchanger, and electrolytic cell are connected in series via pipelines; a three-way valve and a first water pump are installed on the pipeline between the circulating water tank and the heat exchanger. The outlet of the electrolytic cell is connected to the circulating water tank through a pipeline equipped with a first solenoid valve; the outlet of the electrolytic cell is connected to the inlet of the first steam-water separator through a pipeline equipped with a second solenoid valve; the outlet of the first steam-water separator is connected to the circulating water tank through a pipeline. The outlet of the circulating water tank, the outlet of the first water pump, and the outlet of the first steam-water separator are connected to a three-way valve; The control system is used to control the opening and closing of the first and second solenoid valves, the valve opening degree of the three-way valve, the speed of the first water pump, and the current of the electrolytic cell.

2. The PEM water electrolysis hydrogen production system as described in claim 1, characterized in that, A third solenoid valve is installed on the pipeline between the water purifier and the temperature-controlled water tank, and a fourth solenoid valve is installed on the pipeline between the temperature-controlled water tank and the circulating water tank; the temperature-controlled water tank is equipped with a heating module, which is electrically connected to the control system.

3. The PEM water electrolysis hydrogen production system as described in claim 1, characterized in that, It also includes a temperature acquisition unit, a liquid level acquisition unit, and a flow acquisition unit. The temperature acquisition unit is used to acquire the temperature values ​​of the temperature-controlled water tank, the circulating water tank, the inlet of the electrolytic cell, and the outlet of the electrolytic cell. The liquid level acquisition unit is used to acquire the liquid level of the temperature-controlled water tank and the circulating water tank. The flow acquisition unit is used to acquire the inlet flow rate of the electrolytic cell.

4. The PEM water electrolysis hydrogen production system as described in claim 1, characterized in that, It also includes a chiller, which is circulated with the heat exchanger through a first pipeline and a second pipeline; the second pipeline is equipped with an electrically operated valve.

5. The PEM water electrolysis hydrogen production system as described in claim 4, characterized in that, It also includes a heat recovery system, which is connected to the first pipeline via a third pipeline, and a third solenoid valve is installed on the third pipeline; the heat recovery system is connected to the second pipeline between the electric opening valve and the heat exchanger via a fourth pipeline; a second water pump is installed on the fourth pipeline.

6. The PEM water electrolysis hydrogen production system as described in claim 1, characterized in that, It also includes a second steam-water separator, a condenser, and a hydrogen purification system; the second steam-water separator is connected to the outlet of the electrolytic cell, the outlet of the second steam-water separator is connected to the condenser, and the condenser is connected to the hydrogen purification system.

7. The PEM water electrolysis hydrogen production system as described in claim 6, characterized in that, The liquid outlet of the second steam-water separator and condenser is connected to the liquid sealing device through a fifth pipeline, and the liquid sealing device is connected to the temperature-controlled water tank; a pressure buffer tank is installed on the fifth pipeline.

8. The PEM water electrolysis hydrogen production system as described in claim 1, characterized in that, It also includes an oxygen treatment system, which is connected to a circulating water tank.

9. The control method for the PEM water electrolysis hydrogen production system according to any one of claims 1 to 8, characterized in that, Includes the following steps: When the PEM water electrolysis hydrogen production system is started, water in the circulating water tank enters the electrolyzer through the three-way valve. When the water flow reaches the idle flow rate, the first solenoid valve is closed, the second solenoid valve is opened, and the valve opening of the three-way valve is adjusted so that the liquid output of the circulating water tank is 0. The current of the electrolyzer is gradually increased according to the measured value of the inlet temperature of the electrolyzer, and the speed of the first water pump is adjusted according to the current value until the rated current is reached. Once the inlet temperature of the electrolytic cell is greater than or equal to the target temperature, open the first solenoid valve and control the opening of the three-way valve to gradually increase the liquid output of the circulating water tank and gradually decrease the liquid output of the first steam-water separator, thereby controlling the inlet temperature of the electrolytic cell to remain constant until the liquid output of the first steam-water separator is 0. Then close the second solenoid valve to reach the stable operation stage.

10. The control method as described in claim 9, characterized in that, When the PEM water electrolysis hydrogen production system is started, it also includes adjusting the temperature of the temperature-controlled water tank to reach the preset temperature value and controlling the root mean square error of the temperature in the temperature-controlled water tank to be less than the preset value; monitoring the liquid level of the circulating water tank, and controlling the temperature-controlled water tank to replenish water when the measured liquid level is lower than the preset liquid level value.

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