Water electrolysis hydrogen production system with cascade water replenishing function and control method

Abstract

The invention discloses a cascade water replenishing water electrolysis hydrogen production system and a control method. The system comprises a raw material water circulation loop, a water storage tank gas inlet pipeline, an oxygen separator water replenishing pipeline, a water storage tank gas exhaust pipeline and a water storage tank water replenishing pipeline. An oxygen separator is arranged in the raw material water circulation loop, the exhaust end of the oxygen separator is connected with the gas inlet end of the water storage tank through a gas inlet pipeline of the water storage tank, and the water supplementing end of the oxygen separator is connected with the water outlet end of the water storage tank through a water supplementing pipeline of the oxygen separator; the exhaust end of the water storage tank is connected with a water storage tank exhaust pipeline, and the water replenishing end is connected with a water storage tank water replenishing pipeline; the spatial position of the water storage tank is higher than that of the oxygen separator, and relative low-pressure water replenishing of the water storage tank and relative high-pressure water replenishing of the oxygen separator can be completed through valve linkage of the water storage tank air inlet pipeline, the oxygen separator water replenishing pipeline, the water storage tank exhaust pipeline and the water storage tank water replenishing pipeline. Therefore, cascade water replenishing of the raw material water circulation loop is achieved, and extra power input is not needed.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis hydrogen production, and in particular to a water electrolysis hydrogen production system with cascade water replenishment and a control method. Background Art

[0002] As a clean and sustainable way to produce hydrogen, water electrolysis is an important way to achieve clean energy conversion and storage, and has gradually become one of the important directions for the development of hydrogen energy. Since water electrolysis is a process that uses electrical energy to electrolyze water to produce oxygen and hydrogen, raw water (referring to the water participating in the electrolysis cycle in the hydrogen production system, the same below) is continuously consumed during the operation of the hydrogen production system, so it is necessary to regularly replenish raw water into the system to ensure the continuous and safe operation of the hydrogen production system. At present, the water replenishment in conventional water electrolysis hydrogen production systems is basically completed by diaphragm pumps (or plunger pumps), and the high head characteristics of diaphragm pumps (or plunger pumps) are used to directly inject raw water into the hydrogen production system to achieve water replenishment. However, with the increasing working pressure of the hydrogen production system and the requirements for system integration, the shortcomings of using a high-pressure pump to directly replenish water to the hydrogen production system are obvious:

[0003] (1) Loud noise and strong vibration. During operation, the diaphragm pump (or plunger pump) continuously vibrates due to the piston movement of the pump head. The higher the back pressure, the stronger the vibration and noise.

[0004] (2) The system is complex and occupies a large area. The water replenishment device in the conventional water electrolysis hydrogen production system at least includes a water tank, a diaphragm pump (or a plunger pump), a safety valve, a damper, a manual valve and a piping system. Its process is complex and occupies a large area, which is not conducive to system integration.

[0005] (3) High power consumption and high operating costs. In conventional water electrolysis hydrogen production systems, the water supply pump needs to pressurize the raw water from low pressure to high pressure, so its motor power is relatively large and is linearly related to the hydrogen production pressure. Summary of the invention

[0006] In order to solve the problems of vibration, noise and so on in the water replenishment device of the conventional water electrolysis hydrogen production system, the present invention proposes a water electrolysis hydrogen production system with cascade water replenishment and a control method. Through clever operation control and three-dimensional spatial layout, the water replenishment operation of the hydrogen production system is realized in stages without the need for additional power input.

[0007] The technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a water electrolysis hydrogen production system with cascade water replenishment, comprising:

[0009] Raw water circulation loop, water tank air intake pipeline, oxygen separator water supply pipeline, water tank exhaust pipeline and water tank water supply pipeline;

[0010] An oxygen separator is provided in the raw water circulation loop, the exhaust end of the oxygen separator is connected to the air inlet end of the water storage tank through the air inlet pipeline of the water storage tank, and the water supply end of the oxygen separator is connected to the water outlet end of the water storage tank through the water supply pipeline of the oxygen separator; the exhaust end of the water storage tank is connected to the exhaust pipeline of the water storage tank, and the water supply end is connected to the water supply pipeline of the water storage tank;

[0011] The spatial position of the water storage tank is higher than that of the oxygen separator. By means of the valve linkage of the water storage tank air intake pipeline, the oxygen separator water supply pipeline, the water storage tank exhaust pipeline and the water storage tank water supply pipeline, relatively low-pressure water supply to the water storage tank and relatively high-pressure water supply to the oxygen separator can be completed, thereby realizing cascade water supply to the raw water circulation loop.

[0012] Furthermore, the raw water circulation loop includes an oxygen separator, a raw water circulation pump, a raw water heat exchanger and an electrolytic cell, and the oxygen separator, the raw water circulation pump, the raw water heat exchanger and the electrolytic cell are connected end to end; the oxygen separator is provided with a second liquid level gauge for liquid level monitoring.

[0013] Furthermore, a first automatic valve is provided on the air inlet pipeline of the water storage tank. When the water electrolysis hydrogen production system needs to be replenished with water, the first automatic valve is opened to inflate the water storage tank.

[0014] Furthermore, a third check valve is provided on the water supply pipeline of the oxygen separator, and the third check valve is configured to prevent the water in the oxygen separator from flowing back into the water storage tank.

[0015] Furthermore, the pressure difference formed by the height between the water storage tank and the oxygen separator needs to be greater than the sum of the opening pressure of the third check valve and the resistance along the water supply pipeline of the oxygen separator.

[0016] Furthermore, a second automatic valve and a first check valve are provided on the exhaust pipe of the water storage tank. When the water electrolysis hydrogen production system completes water replenishment, the second automatic valve is turned on to discharge the water storage tank to a slightly positive pressure, preparing for water replenishment of the water storage tank; the first check valve is configured to prevent air from backflowing into the water storage tank.

[0017] Furthermore, a second check valve and a third automatic valve are provided on the water tank water replenishment pipeline. When the liquid level monitored by the first liquid level gauge on the water tank is lower than a preset value, the third automatic valve is turned on to replenish the water tank; the second check valve is configured to prevent the water in the water tank from backflowing and causing the pressure at the inlet end of the water tank water replenishment pipeline to increase.

[0018] Furthermore, the water tank is provided with a pressure transmitter, an on-site pressure gauge and a first liquid level gauge. The pressure transmitter and the on-site pressure gauge are configured to monitor the pressure of the water tank and compare with each other. The first liquid level gauge is configured to monitor the liquid level of the water tank.

[0019] Furthermore, the outlet end of the oxygen separator water supply pipeline is arranged below the lowest liquid level of the oxygen separator, and the outlet of the water tank water supply pipeline is arranged below the lowest liquid level of the water tank.

[0020] On the other hand, the present invention provides a control method for a water electrolysis hydrogen production system with cascade water replenishment, comprising:

[0021] When the water electrolysis hydrogen production system is in operation, the pressure transmitter and the first liquid level gauge on the water storage tank monitor the state of the water storage tank in real time. When the liquid level monitored by the first liquid level gauge is lower than the preset value and the pressure monitored by the pressure transmitter is a slightly positive pressure, the water supply pipeline of the water storage tank is connected to replenish water to the water storage tank;

[0022] As the electrolysis process proceeds, the raw water in the raw water circulation loop is continuously consumed. When the liquid level monitored by the second liquid level gauge on the oxygen separator is lower than the preset value, the second automatic valve on the exhaust pipeline of the water storage tank and the third automatic valve on the water supply pipeline of the water storage tank are closed, and the first automatic valve on the air inlet pipeline of the water storage tank is turned on to inflate and pressurize the water storage tank, and then the ultrapure water in the water storage tank is replenished into the oxygen separator;

[0023] After the water electrolysis hydrogen production system is replenished with water, the first automatic valve is closed and the second automatic valve is turned on. After the pressure monitored by the pressure transmitter reaches a slightly positive pressure, the second automatic valve is closed to complete a water replenishment cycle.

[0024] The beneficial effects of the present invention are:

[0025] Due to the vibration, noise and other problems in the water replenishment device of the conventional water electrolysis hydrogen production system, the present invention realizes the water replenishment of the hydrogen production system in stages through the linkage of the water storage tank and its affiliated pipelines. Its characteristics and advantages are as follows:

[0026] 1. The present invention optimizes the water replenishment process of the hydrogen production system, abandons the moving equipment in the conventional system, and avoids the problems of vibration, noise and high power consumption during the operation of the water replenishment pump.

[0027] 2. The present invention uses the product gas of water electrolysis to pressurize and release the water storage tank, and realizes the water replenishment of the hydrogen production system in stages. Among them, the low-pressure water replenishment has low power, and the high-pressure water replenishment power is self-sufficient. The whole water replenishment process is gentle and sustainable.

[0028] 3. The present invention combines an automatic valve with a control system to monitor the hydrogen production system in real time, thereby achieving low energy consumption, orderliness and automation of water replenishment in the hydrogen production system, greatly ensuring the safety of the water replenishment process.

[0029] In summary, the present invention uses a water tank as an intermediary, uses a pure water device to replenish the water tank to the designed liquid level when the water tank is under low pressure, and then pressurizes the water tank with oxygen, and combines the gravity field to realize water replenishment for the oxygen separator. The present invention optimizes the hydrogen production system process, removes the water replenishment pump in the conventional hydrogen production system, avoids the vibration problem caused by the operation of the water replenishment pump, reduces the equipment footprint, improves the system integration, and reduces the operating power consumption of the hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of a water electrolysis hydrogen production system with cascade water replenishment in Example 1 of the present invention.

[0031] Figure 2 This is a flow chart of a control method for a water electrolysis hydrogen production system with cascade water replenishment in Example 3 of the present invention. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] like Figure 1 As shown, this embodiment provides a water electrolysis hydrogen production system with cascade water replenishment, including a raw water circulation loop S101, a water tank air inlet pipeline S102, an oxygen separator water replenishment pipeline S103, a water tank exhaust pipeline S104 and a water tank water replenishment pipeline S105; wherein an oxygen separator 1 is arranged in the raw water circulation loop S101, the exhaust end of the oxygen separator 1 is connected to the air inlet end of the water tank 8 through the water tank air inlet pipeline S102, and the water replenishment end of the oxygen separator 1 is connected to the water outlet end of the water tank 8 through the oxygen separator water replenishment pipeline S103; the exhaust end of the water tank 8 is connected to the water tank exhaust pipeline S104, and the water replenishment end is connected to the water tank water replenishment pipeline S105.

[0035] In this embodiment, the spatial position of the water tank 8 is higher than that of the oxygen separator 1. Through the valve linkage of the water tank air intake pipeline S102, the oxygen separator water replenishment pipeline S103, the water tank exhaust pipeline S104 and the water tank water replenishment pipeline S105, relatively low-pressure water replenishment of the water tank 8 and relatively high-pressure water replenishment of the oxygen separator 1 can be completed, thereby realizing the cascade water replenishment of the raw water circulation loop S101.

[0036] The raw water circulation loop S101 is a necessary loop of the water electrolysis hydrogen production system, and its function is to provide raw materials for the electrolysis process and take away excess heat. Preferably, the raw water circulation loop S101 includes an oxygen separator 1, a raw water circulation pump 3, a raw water heat exchanger 4 and an electrolyzer 5, and the oxygen separator 1, the raw water circulation pump 3, the raw water heat exchanger 4 and the electrolyzer 5 are connected end to end. The raw water enters the raw water heat exchanger 4 from the lower end of the oxygen separator 1 through the raw water circulation pump 3 for heat exchange, and after cooling to an appropriate temperature, enters the electrolyzer 5 for electrolysis. The hydrogen produced by the electrolysis enters the hydrogen post-processing system ( Figure 1 The oxygen generated by electrolysis enters the oxygen separator 1 for gas-water separation, completing an electrolysis cycle. Raw water is continuously consumed during the electrolysis process, so it is necessary to monitor the values ​​of the first liquid level gauge 13 on the water storage tank 8 and the second liquid level gauge 2 on the oxygen separator 1, and replenish water through the linkage of the automatic valve to keep the above liquid levels in a healthy state.

[0037] The water tank air inlet pipeline S102 should connect the oxygen separator 1 with the gas phase space of the water tank 8 to reduce pipeline resistance. Preferably, a first automatic valve 6 is provided on the water tank air inlet pipeline S102. When the water electrolysis hydrogen production system needs to be replenished with water, the first automatic valve 6 is opened to inflate the water tank 8.

[0038] Preferably, a third check valve 7 is provided on the oxygen separator water supply pipeline S103, and the third check valve 7 is configured to prevent the water in the oxygen separator 1 from flowing back into the water storage tank 8. More preferably, the opening pressure of the third check valve 7 should not be greater than 2Kpa, and the pressure drop of the oxygen separator water supply pipeline S103 should not be greater than 3Kpa.

[0039] Preferably, the pressure difference formed by the height between the water storage tank 8 and the oxygen separator 1 needs to be greater than the sum of the opening pressure of the third check valve 7 and the resistance along the oxygen separator water supply pipeline S103.

[0040] Preferably, a second automatic valve 11 and a first check valve 12 are provided on the water tank exhaust pipeline S104. When the water electrolysis hydrogen production system completes water replenishment, the second automatic valve 11 is turned on to discharge the water tank 8 to a slightly positive pressure, preparing for water replenishment of the water tank 8; the first check valve 12 is configured to prevent air from backflowing into the water tank 8.

[0041] The purpose of the water tank replenishment pipeline S105 is to replenish water for the water tank 8. Preferably, a second check valve 14 and a third automatic valve 15 are provided on the water tank replenishment pipeline S105. When the liquid level monitored by the first liquid level meter 13 on the water tank 8 is lower than a preset value, the third automatic valve 15 is turned on to replenish water to the water tank 8 through the pure water equipment 16; the second check valve 14 is configured to prevent the water from backflowing from the water tank 8, which causes the pressure at the inlet end of the water tank replenishment pipeline S105 to increase.

[0042] Preferably, the water storage tank 8 is provided with a pressure transmitter 9, an on-site pressure gauge 10 and a first liquid level gauge 13. The pressure transmitter 9 and the on-site pressure gauge 10 are configured to monitor the pressure of the water storage tank 8 and compare with each other to further ensure the safety of the hydrogen production system; the first liquid level gauge 13 is configured to monitor the liquid level of the water storage tank 8.

[0043] Preferably, the outlet end of the oxygen separator water supply pipeline S103 is arranged below the lowest liquid level of the oxygen separator 1 to act as a water seal; the outlet of the water storage tank water supply pipeline S105 is arranged below the lowest liquid level of the water storage tank 8 to prevent gas backflow.

[0044] Preferably, the height difference between the bottom of the water storage tank 8 and the highest liquid level of the oxygen separator 1 is ≮0.5 m, so as to ensure that ultrapure water can enter the oxygen separator 1 when the water storage tank 8 and the oxygen separator 1 are at equal pressure.

[0045] In addition, the first automatic valve 6 is preferably a normally closed valve, the second automatic valve 11 is preferably a normally open valve, and the third automatic valve 15 is preferably a normally closed valve; the first check valve 12, the second check valve 14 and the third check valve 7 are preferably axial flow check valves with an opening pressure of <2Kpa.

[0046] In summary, the water electrolysis hydrogen production system of this embodiment removes the water replenishment pump in the conventional process, and completes the water replenishment of the water electrolysis hydrogen production system in stages by pressurizing and depressurizing the water storage tank 8, thereby ensuring low power consumption, weak vibration and safety during water replenishment of the water electrolysis hydrogen production system. Since the high-pressure water replenishment process is self-sufficient in power, the water replenishment equipment is reduced in size while reducing the operating cost of the water electrolysis hydrogen production system.

[0047] Example 2

[0048] This embodiment is based on embodiment 1:

[0049] This embodiment provides a control method for a water electrolysis hydrogen production system with cascade water replenishment, comprising the following steps:

[0050] When the water electrolysis hydrogen production system is running, the pressure transmitter 9 and the first liquid level gauge 13 on the water storage tank 8 monitor the state of the water storage tank 8 in real time. When the liquid level monitored by the first liquid level gauge 13 is lower than the preset value and the pressure monitored by the pressure transmitter 9 is a slightly positive pressure, the water tank water replenishment pipeline S105 is connected to replenish water to the water storage tank 8;

[0051] As the electrolysis process proceeds, the raw water in the raw water circulation loop S101 is continuously consumed. When the liquid level monitored by the second liquid level meter 2 on the oxygen separator 1 is lower than the preset value, the second automatic valve 11 on the water tank exhaust pipeline S104 and the third automatic valve 15 on the water tank water supply pipeline S105 are closed, and the first automatic valve 6 on the water tank air intake pipeline S102 is turned on to inflate and pressurize the water tank 8, and then the ultrapure water in the water tank 8 is replenished into the oxygen separator 1;

[0052] After the water electrolysis hydrogen production system is replenished with water, the first automatic valve 6 is closed, and the second automatic valve 11 is turned on. After the pressure monitored by the pressure transmitter 9 reaches a slightly positive pressure, the second automatic valve 11 is closed to complete a water replenishment cycle.

[0053] Example 3

[0054] This embodiment is based on embodiment 1:

[0055] like Figure 2 As shown, this embodiment provides a control method for a water electrolysis hydrogen production system with cascade water replenishment, comprising the following steps:

[0056] The water electrolysis hydrogen production system is running. When the liquid level of the first liquid level gauge 13 (i.e., the liquid level of the water storage tank 8) is lower than the design value, and the electrolysis cycle water replenishment process is not in progress or has ended (i.e., the first automatic valve 6 is in a closed state), it is necessary to determine whether the pressure in the water storage tank 8 is in a slightly positive pressure (0.1-0.2Mpa, the same below). If so, start the pure water equipment 16 to replenish the water storage tank 8; if not, keep the second automatic valve 11 in an open state until the water storage tank 8 becomes a slightly positive pressure, and continue to replenish water until the liquid level of the water storage tank 8 reaches the design value. In short, when the electrolysis cycle is not in progress, it is necessary to keep the liquid level of the water storage tank 8 at the design value. This is the first-level water replenishment of the water electrolysis hydrogen production system. The water replenishment port of the water storage tank 8 is directly connected to the water outlet of the pure water equipment 16, which is low-pressure water replenishment.

[0057] As the electrolysis process continues, when the liquid level of the second liquid level gauge 2 (i.e., the liquid level of the oxygen separator 1) is lower than the design value, the electrolysis cycle should be replenished. When the liquid level of the first liquid level gauge 13 (i.e., the liquid level of the water storage tank 8) reaches the design value, close the second automatic valve 11 and the third automatic valve 15, open the first automatic valve 6, and part of the oxygen in the oxygen separator 1 enters the water storage tank 8 until the pressure of the oxygen separator 1 is equal to that of the water storage tank 8, and the ultrapure water in the water storage tank 8 is replenished into the oxygen separator 1 through the height difference. When the liquid level of the second liquid level gauge 2 reaches the design value, the water electrolysis hydrogen production system completes the water replenishment. At this time, close the first automatic valve 6 and open the second automatic valve 11 at the same time to restore the water storage tank 8 to a slightly positive pressure. This is the secondary water replenishment of the water electrolysis hydrogen production system. The water replenishment power is oxygen, one of the electrolysis product gases, and it is high-pressure water replenishment.

[0058] The operating status of the above-mentioned water electrolysis hydrogen production system can be monitored by the control system and the water replenishment operation can be automatically performed, thereby ensuring the safe, stable and continuous operation of the water electrolysis hydrogen production system.

[0059] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A water electrolysis hydrogen production system with cascade water replenishment, characterized in that: include: Raw water circulation loop (S101), water tank air intake pipeline (S102), oxygen separator water supply pipeline (S103), water tank exhaust pipeline (S104) and water tank water supply pipeline (S105); An oxygen separator (1) is provided in the raw water circulation loop (S101); the exhaust end of the oxygen separator (1) is connected to the air inlet end of the water storage tank (8) through the water storage tank air inlet pipeline (S102); the water supply end of the oxygen separator (1) is connected to the water outlet end of the water storage tank (8) through the oxygen separator water supply pipeline (S103); the exhaust end of the water storage tank (8) is connected to the water storage tank exhaust pipeline (S104), and the water supply end is connected to the water storage tank water supply pipeline (S105); The spatial position of the water storage tank (8) is higher than that of the oxygen separator (1). By means of the valve linkage of the water storage tank air intake pipeline (S102), the oxygen separator water supply pipeline (S103), the water storage tank exhaust pipeline (S104) and the water storage tank water supply pipeline (S105), relatively low-pressure water supply to the water storage tank (8) and relatively high-pressure water supply to the oxygen separator (1) can be completed, thereby realizing cascade water supply to the raw water circulation loop (S101).

2. A water electrolysis hydrogen production system with cascade water replenishment according to claim 1, characterized in that: The raw water circulation loop (S101) comprises an oxygen separator (1), a raw water circulation pump (3), a raw water heat exchanger (4) and an electrolytic cell (5), wherein the oxygen separator (1), the raw water circulation pump (3), the raw water heat exchanger (4) and the electrolytic cell (5) are connected end to end; and a second liquid level meter (2) for liquid level monitoring is provided on the oxygen separator (1).

3. The water electrolysis hydrogen production system with cascade water replenishment according to claim 1 is characterized in that: The water tank air inlet pipeline (S102) is provided with a first automatic valve (6). When the water electrolysis hydrogen production system needs to be replenished with water, the first automatic valve (6) is opened to inflate the water tank (8).

4. The water electrolysis hydrogen production system with cascade water replenishment according to claim 1 is characterized in that: The oxygen separator water supply pipeline (S103) is provided with a third check valve (7), and the third check valve (7) is configured to prevent the water in the oxygen separator (1) from flowing back into the water storage tank (8).

5. A water electrolysis hydrogen production system with cascade water replenishment according to claim 4, characterized in that: The pressure difference formed by the height between the water storage tank (8) and the oxygen separator (1) must be greater than the sum of the opening pressure of the third check valve (7) and the resistance along the oxygen separator water supply pipeline (S103).

6. The water electrolysis hydrogen production system with cascade water replenishment according to claim 1, characterized in that: The water tank exhaust pipeline (S104) is provided with a second automatic valve (11) and a first check valve (12). When the water electrolysis hydrogen production system completes water replenishment, the second automatic valve (11) is turned on to discharge the water tank (8) to a slightly positive pressure, in preparation for water replenishment of the water tank (8); the first check valve (12) is configured to prevent air from backflowing into the water tank (8).

7. The water electrolysis hydrogen production system with cascade water replenishment according to claim 1, characterized in that: The water tank water replenishment pipeline (S105) is provided with a second check valve (14) and a third automatic valve (15); when the liquid level monitored by the first liquid level meter (13) on the water tank (8) is lower than a preset value, the third automatic valve (15) is turned on to replenish the water tank (8); the second check valve (14) is configured to prevent the water in the water tank (8) from flowing back and causing the pressure at the inlet end of the water tank water replenishment pipeline (S105) to increase.

8. The water electrolysis hydrogen production system with cascade water replenishment according to claim 1, characterized in that: The water storage tank (8) is provided with a pressure transmitter (9), an on-site pressure gauge (10) and a first liquid level gauge (13); the pressure transmitter (9) and the on-site pressure gauge (10) are configured to monitor the pressure of the water storage tank (8) and compare them with each other; the first liquid level gauge (13) is configured to monitor the liquid level of the water storage tank (8).

9. The water electrolysis hydrogen production system with cascade water replenishment according to claim 1, characterized in that: The outlet end of the oxygen separator water supply pipeline (S103) is arranged below the lowest liquid level of the oxygen separator (1), and the outlet of the water storage tank water supply pipeline (S105) is arranged below the lowest liquid level of the water storage tank (8).

10. A control method for a water electrolysis hydrogen production system with cascade water replenishment, applied to the water electrolysis hydrogen production system according to claim 1, characterized in that: The control method comprises: When the water electrolysis hydrogen production system is in operation, the pressure transmitter (9) and the first liquid level gauge (13) on the water storage tank (8) monitor the state of the water storage tank (8) in real time. When the liquid level monitored by the first liquid level gauge (13) is lower than a preset value and the pressure monitored by the pressure transmitter (9) is a slightly positive pressure, the water tank water replenishment pipeline (S105) is opened to replenish the water storage tank (8); As the electrolysis process proceeds, the raw water in the raw water circulation loop (S101) is continuously consumed. When the liquid level monitored by the second liquid level meter (2) on the oxygen separator (1) is lower than a preset value, the second automatic valve (11) on the water storage tank exhaust pipeline (S104) and the third automatic valve (15) on the water storage tank water supply pipeline (S105) are closed, and the first automatic valve (6) on the water storage tank air intake pipeline (S102) is opened to inflate and pressurize the water storage tank (8), and then the ultrapure water in the water storage tank (8) is replenished into the oxygen separator (1); After the water electrolysis hydrogen production system is replenished with water, the first automatic valve (6) is closed, and the second automatic valve (11) is opened. After the pressure monitored by the pressure transmitter (9) reaches a slightly positive pressure, the second automatic valve (11) is closed to complete a water replenishment cycle.

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