Preparation device and preparation method of heavy water

Abstract

The invention provides a heavy water preparation device. The heavy water preparation device comprises an external water storage unit, an electrolysis unit, an internal water storage unit and a control unit, the electrolysis unit comprises an electrolytic bath, an electrolysis power supply, a cathode side gas-liquid separator and an anode side gas-liquid separator; the electrolysis units and the internal water storage units are connected in series to form a plurality of stages, and the internal water storage units of the adjacent units are connected. The invention also provides a method for preparing heavy water by using the heavy water preparation device. The invention provides a heavy water preparation device which is formed by connecting multiple stages of electrolysis units and an internal water storage unit in series, by means of the arrangement mode of the electrolysis units, heavy water can be prepared through step-by-step electrolysis, that is, heavy water obtained at the previous stage is enriched and then provided for electrolysis at the next stage, and the enrichment abundance of the heavy water is rapidly increased; furthermore, a specific electrolytic bath is introduced into the electrolysis unit, so that the power consumption can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electrolyzed water, and in particular to a device and method for preparing heavy water. Background Art

[0002] In nature, hydrogen exists in the form of three isotopes: 1H (protium, H), 2H (deuterium, D), and 3H (tritium, T), with relative abundances of about 99.985%, about 0.015%, and less than 0.001%, respectively. Heavy water (Deuterium oxide) is a compound composed of deuterium and oxygen, also known as deuterium oxide (D2O). The cost of refining heavy water is very high, and due to its use in nuclear fuel, heavy water is subject to many restrictions, so the price is very high.

[0003] At present, heavy water is often produced commercially by electrolysis of an alkaline aqueous solution of sodium or potassium hydroxide or carbonate. Continuous electrolysis may produce high-purity heavy water. However, a large amount of electricity is required to obtain high-concentration heavy water, so it is basically not feasible to use this electrolysis method to extract heavy water from ordinary water. However, when the feed water has been partially concentrated by other methods, electrolysis is a particularly valuable method.

[0004] SPE electrolysis hydrogen production technology uses thinner ion-conducting diaphragms and membrane electrodes. Compared with traditional alkaline electrolysis methods, the operating current density is significantly higher, the volume is smaller, and it has fast response capabilities and high hydrogen production efficiency. After the iterative improvement of SPE electrolysis technology in recent years, it can provide up to 3A / cm at a lower voltage. 2 The electrolysis current density makes it possible to extract heavy water from ordinary deionized water. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a heavy water preparation device. The preparation device provided by the present application can realize the rapid enrichment of heavy water and the rapid increase of abundance.

[0006] In view of this, the present application provides a heavy water preparation device, comprising an external water storage unit, an electrolysis unit, an internal water storage unit and a control unit;

[0007] The electrolysis unit comprises an electrolytic cell, an electrolysis power supply, a cathode-side gas-liquid separator and an anode-side gas-liquid separator;

[0008] The electrolytic power supply is connected to the electrolytic cell to control the opening and closing of the electrolytic cell;

[0009] The control unit is connected to the external water storage unit, the electrolysis unit and the internal water storage unit respectively, so as to detect and control the operation of the electrolysis in real time;

[0010] The outlet of the external water storage unit is connected to the inlet of the internal water storage unit, the liquid outlet of the internal water storage unit is connected to the liquid inlet of the electrolyzer, the liquid outlet of the electrolyzer is connected to the first liquid inlet of the internal water storage unit, the cathode side gas outlet of the electrolyzer is connected to the gas inlet of the cathode side gas-liquid separator, the anode side gas outlet of the electrolyzer is connected to the gas inlet of the anode side gas-liquid separator, and the liquid outlet of the cathode side gas-liquid separator and the liquid outlet of the anode side gas-liquid separator are both connected to the second liquid inlet of the internal water storage unit;

[0011] The electrolysis units and the internal water storage units are connected in series in several stages according to the above connection method; the internal water storage units of adjacent units are connected.

[0012] Preferably, a water replenishment pump is provided between the external water storage unit and the internal water storage unit.

[0013] Preferably, the electrolysis unit further comprises a condenser, and the condenser is arranged between the electrolysis cell and the anode-side gas-liquid separator.

[0014] Preferably, the electrolysis unit is further provided with a temperature sensor, and the temperature sensor is connected to the electrolytic cell.

[0015] Preferably, a circulating water pump is provided between the internal water storage unit and the electrolytic cell.

[0016] Preferably, the number of levels is 3 to 4 levels.

[0017] Preferably, the electrolytic cell is a solid polymer electrolyte water electrolysis device, and the membrane electrodes in the electrolytic cell are connected in series and / or in parallel.

[0018] The present application also provides a method for preparing heavy water using the device, comprising the following steps:

[0019] A) adding water from the external water storage unit to the primary internal water storage unit until the water level of the primary internal water storage unit reaches an upper threshold value, and the control unit controls the primary electrolysis unit to perform electrolysis;

[0020] B) the oxygen and hydrogen generated in the electrolytic cell of the primary electrolysis unit enter the anode side gas-liquid separator and the cathode side gas-liquid separator respectively, and the separated water enters the primary internal water storage unit again for electrolysis again and then enters the primary internal water storage unit;

[0021] C) replenishing the water of the primary internal water storage unit obtained in step B) to the secondary internal water storage unit, and when the water of the primary internal water storage unit is lower than the lower limit threshold, the replenishment ends, the secondary electrolysis unit starts electrolysis, and step B) is repeated;

[0022] The water in the first-level internal water storage unit is replenished to the upper water level threshold before electrolysis begins; and the water obtained after each level of electrolysis unit completes electrolysis is replenished to the next level until each level of electrolysis unit performs electrolysis.

[0023] Preferably, when there are four levels of internal water storage units, the number of membrane electrodes of the first-level electrolysis unit is greater than the number of membrane electrodes of the second-level electrolysis unit, which is greater than the number of membrane electrodes of the third-level electrolysis unit, which is greater than the number of membrane electrodes of the fourth-level electrolysis unit.

[0024] Preferably, when the temperature of the electrolytic cell is higher than 50°C, the condenser is started to cool down.

[0025] The present application provides a heavy water preparation device, which is composed of a multi-stage electrolysis unit and an internal water storage unit connected in series. The arrangement of the electrolysis unit can realize the step-by-step electrolysis to prepare heavy water, that is, the heavy water obtained in the previous stage is enriched and provided to the next stage for electrolysis, so that the abundance of heavy water enrichment increases rapidly; further, the electrolysis unit of the present application adopts a specific electrolytic cell, which can effectively reduce power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a heavy water preparation device provided by the present invention;

[0027] Figure 2 This is a schematic diagram of the specific operation process in the heavy water preparation process of the present invention;

[0028] Figure 3 The figure is a schematic diagram of the control flow in the heavy water preparation process of the present invention. DETAILED DESCRIPTION

[0029] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0030] In view of the shortcoming of high power consumption in the preparation of heavy water by traditional technology, the SPE electrolysis technology adopted in the present invention has higher electrolysis efficiency. SPE is a water electrolysis hydrogen production technology that uses a solid polymer membrane as an electrolyte, generally referring to a proton exchange membrane (PEM), such as a Nafion-type solid polymer membrane, which mainly provides a channel for proton transmission and isolates the penetration and mixing of product gases; at the same time, the present invention adopts a step-by-step electrolysis preparation method, and the previous stage will provide the D2O-enriched heavy water to the next stage of electrolysis, which can rapidly increase the abundance of D2O enrichment. Specifically, the present application provides a heavy water preparation device, and the structural schematic diagram is shown in FIG. Figure 1As shown, 1 is a liquid level sensor, 2 is an electrolytic cell, 3 is a water supply pump, 4 is a water outlet pump, 5 is an external water storage tank, 6 is an electrolysis power supply, 7 is a cathode side gas-liquid separator, 8 is a temperature sensor, 9 is an anode side gas-liquid separator, 10 is a condenser, 11 is a circulating water pump, 12 is an internal water storage tank, 13 is a microcontroller, and 14 is a host computer.

[0031] The heavy water preparation device provided in the present application comprises an external water storage unit, an electrolysis unit, an internal water storage unit and a control unit;

[0032] The electrolysis unit comprises an electrolytic cell, an electrolysis power supply, a cathode-side gas-liquid separator, and an anode-side gas-liquid separator;

[0033] The electrolytic power supply is connected to the electrolytic cell to control the opening and closing of the electrolytic cell;

[0034] The control unit is connected to the external water storage unit, the electrolysis unit and the internal water storage unit respectively, so as to detect and control the operation of the electrolysis in real time;

[0035] The outlet of the external water storage unit is connected to the inlet of the internal water storage unit, the liquid outlet of the internal water storage unit is connected to the liquid inlet of the electrolyzer, the liquid outlet of the electrolyzer is connected to the first liquid inlet of the internal water storage unit, the cathode side gas outlet of the electrolyzer is connected to the gas inlet of the cathode side gas-liquid separator, the anode side gas outlet of the electrolyzer is connected to the gas inlet of the anode side gas-liquid separator, and the liquid outlet of the cathode side gas-liquid separator and the liquid outlet of the anode side gas-liquid separator are both connected to the second liquid inlet of the internal water storage unit;

[0036] The electrolysis units and the internal water storage units are connected in series in several stages according to the above connection method; the internal water storage units of adjacent units are connected.

[0037] In the present application, a water replenishment pump is provided between the external water storage unit and the internal water storage unit to transport water in the external water storage unit to the internal water storage unit.

[0038] In the specific embodiment provided in the present application, the electrolysis unit also includes a condenser, which is arranged between the electrolytic cell and the anode side gas-liquid separator; it is used to condense the oxygen discharged from the anode of the electrolytic cell, so as to improve the separation effect of the gas-liquid separator on the anode side.

[0039] In a specific embodiment provided in the present application, the electrolysis unit is further provided with a temperature sensor, and the temperature sensor is connected to the electrolytic cell to detect the temperature of the electrolytic cell in real time.

[0040] In the present application, a circulating water pump is provided between the internal water storage unit and the electrolytic cell to transport water in the internal water storage unit to the electrolytic cell for electrolysis.

[0041] In the present application, the electrolysis unit and the internal water storage unit are provided with multiple stages, and two stages, three stages, or four stages can be provided as needed; in the process of producing heavy water by electrolysis, the heavy water in the internal water storage unit of the upper stage enters the lower stage, and then electrolysis is performed to achieve the enrichment of heavy water and improve the abundance of heavy water.

[0042] In the present application, the external water storage unit is specifically an external water storage tank, the internal water storage unit is specifically an internal water storage tank, and the control unit is specifically a host computer and its control software, and a microcontroller. Among them, the host computer and its control software are used to provide an operating interface for setting the electrolysis time for the operator. The microcontroller is used to read the temperature, liquid level, electrolysis current, electrolysis power and other parameters in the electrolysis unit, transmit the read output to the host computer, and receive instructions from the host computer. According to the instructions, the water supply pump, circulation pump, electrolysis power supply and condenser and other devices are controlled to implement the electrolysis task, so as to realize the process control of the entire hydrogen isotope enrichment. The electrolytic cell is a solid polymer electrolyte (SPE) water electrolysis device, which is used to electrolyze pure water into hydrogen and oxygen; the external water storage tank is used to store water for electrolysis; the water pump is used to transport water for electrolysis; the cathode side gas-liquid separator and the anode side gas-liquid separator are used to separate the gas discharged from the electrolytic cell from the water carried therein; the condenser is used to condense the oxygen discharged from the anode of the electrolytic cell, so as to improve the separation effect of the gas-liquid separator on the anode side; the electrolysis power supply is used to provide the required power support for hydrogen isotope enrichment and production.

[0043] The present application also provides a method for preparing heavy water using the above device, comprising the following steps:

[0044] A) adding water from the external water storage unit to the primary internal water storage unit until the water level of the primary internal water storage unit reaches an upper threshold value, and the control unit controls the primary electrolysis unit to perform electrolysis;

[0045] B) the oxygen and hydrogen generated in the electrolytic cell of the primary electrolysis unit enter the anode side gas-liquid separator and the cathode side gas-liquid separator respectively, and the separated water enters the primary internal water storage unit again for electrolysis again and then enters the primary internal water storage unit;

[0046] C) replenishing the water of the primary internal water storage unit obtained in step B) to the secondary internal water storage unit, and when the water of the primary internal water storage unit is lower than the lower limit threshold, the replenishment ends, the secondary electrolysis unit starts electrolysis, and step B) is repeated;

[0047] The water in the first-level internal water storage unit is replenished to the upper water level threshold before electrolysis begins; and the water obtained after each level of electrolysis unit completes electrolysis is replenished to the next level until each level of electrolysis unit performs electrolysis.

[0048] During the preparation of heavy water, the operator sets the task objectives of heavy water preparation, including electrolysis time and heavy water abundance value, through the host computer and its software. The host computer issues instructions to the microcontroller, and the microcontroller controls the devices in the system to implement heavy water preparation. When the heavy water preparation device described in the present application is started for the first time, the water tanks of the electrolysis units at each level are empty, and the first-level internal water tank will draw water from the external water tank to replenish it into the first-level internal water tank until the water level of the first-level internal water tank reaches the upper threshold. After the water replenishment is completed, the microcontroller controls the first-level electrolysis unit to start electrolysis according to the parameters such as the duration and electrolysis current set by the host computer. When the first-level electrolysis unit completes the electrolysis task, the system starts the water replenishment program to extract the water of the first-level internal water tank into the second-level internal water tank. When the water level of the first-level internal water tank is lower than the lower threshold, the water pumping ends, and the second-level electrolysis unit starts electrolysis. The first-level internal water tank is refilled with water and then electrolyzed. Similarly, each level of electrolysis unit will replenish water to the next level after completing electrolysis, and gradually each level will have enough water for electrolysis. The microcontroller monitors the value of the temperature sensor in real time, and starts the condenser fan for heat dissipation when the temperature is higher than 50°C to ensure that the water temperature of the electrolysis is not too high, which leads to insufficient gas-liquid separation.

[0049] The electrolytic cell uses the electric energy provided by the electrolysis power supply to electrolyze water into hydrogen and oxygen; the oxygen and hydrogen produced by the electrolytic cell enter the gas-liquid separator on the anode side and the gas-liquid separator on the cathode side respectively, and the gas-liquid separator uses gravity to discharge the gas and retain the water after electrolysis. The separated water will flow back to the first-level internal water storage tank and continue to circulate into the electrolytic cell for electrolysis. Similarly, for the second-level electrolysis, the water in the first-level internal water storage tank will serve as the electrolysis water source for the second-level internal water storage tank, and the second-level electrolysis unit will further enrich D2O based on the results of the first-level electrolysis. For higher-level electrolysis units, each level is also the water source for electrolysis of the next-level electrolysis unit to ensure that the abundance of heavy water increases step by step after electrolysis. In addition, the electrolysis capacity of the previous level must be higher than that of the next level to ensure that the remaining water after the electrolysis of the previous level can meet the synchronous use of the next level.

[0050] In the present application, the proton membrane (MEA) in each electrolytic cell of the electrolytic unit can be arranged and combined into different electrolytic cells by combining in series and in parallel to work (MEA is a key component of the electrolytic cell, which determines the electrolysis area, electrolysis voltage and electrolysis current of the electrolytic cell, and can be combined in series to form an electrolytic cell); for example: the electrolytic unit requires 250 MEAs for electrolysis, and 250 MEAs can be connected in series to form an electrolytic cell for electrolysis; or 50 MEAs can be connected in series to form an electrolytic cell, with a total of 5 electrolytic cells connected in parallel; or 10 MEAs can be connected in series to form an electrolytic cell, and 25 electrolytic cells can work in parallel, etc. The second method is used in this embodiment, and even if the combination method is different, the total power of electrolysis is unchanged.

[0051] In the present application, the microcontroller starts the circulating liquid pump of each stage to ensure the water circulation of the electrolytic cell; then, an instruction is issued to all the electrolytic units to start the electrolytic power supply to start electrolysis. When the water level of a certain electrolytic unit is lower than the lower threshold, the electrolytic power supply of this electrolytic unit will be shielded and unable to start, so as to protect the anhydrous electrolytic cell from damage caused by electrolysis under anhydrous conditions; at this time, all electrolytic cells with water levels higher than the lower threshold start electrolysis at the same time, and the microcontroller starts electrolysis for a certain period of time according to the setting of the operator. All electrolytic cells with water levels higher than the lower threshold start electrolysis at the same time and end at the same time. After the end, the system will start the water replenishment program, first pumping the water in the last electrolytic unit to the outside of the system until the water level of the last electrolytic unit is lower than the lower threshold, and then replenishing the current level with water from the previous level until the water level of the previous level is lower than the lower threshold, and then continue to replenish water for the previous level. Similarly, until the water level of the first electrolytic unit is pumped to the lower threshold, the first unit is replenished with external deionized water (the specific process is as follows Figure 2 shown).

[0052] More specifically, the above control process is as follows Figure 3As shown, there are two working processes of the electrolysis unit for preparing heavy water in the device, one is the electrolysis process, and the other is the water replenishment process. The host computer and its software control the running time of the electrolysis process according to the set time parameters. Once the electrolysis is completed, the system will enter the water replenishment process. After the water replenishment process is completed, it will enter the electrolysis process again. The two processes run in a cycle. Once the system is shut down and restarted, the system will continue to run according to the previously unfinished program. Assuming that the last level of electrolysis unit is level N, when the system starts the water replenishment process, the microcontroller will pre-judge whether there is water in the last level, that is, whether it is higher than the lower limit threshold of the water level. Once there is water, the system will drain the water. When the lower limit threshold is reached, the system determines that the heavy water of the N-level electrolysis unit has been drained and is in a water shortage state. At this time, the system will detect the lower limit threshold of the water level of the N-1-level electrolysis unit. If this unit is higher than the lower limit threshold, it means that this unit has water. The system will extract water from this unit to replenish water for the N-level electrolysis unit until the N-1-level electrolysis is reached. The lower water level threshold of the unit; if this unit has reached the lower water level threshold, it means that this unit has no water, then the system will determine the lower water level threshold of the N-2 electrolysis unit, the process is the same as the N-1 electrolysis unit, and then determine the lower water level threshold of the N-3 electrolysis unit to replenish the N-2 electrolysis unit, until the first-level electrolysis unit is determined. When the first-level electrolysis unit has reached the lower water level threshold, it will start to replenish water for the first-level electrolysis unit until the first-level electrolysis unit reaches the upper water level threshold, which means that the first-level electrolysis unit has completed water replenishment.

[0053] If the system is started for the first time, since the electrolysis units from level N to level 1 are all at the lower water level threshold, the system will still read the lower water level sensor from the N-level electrolysis unit. When it is read that the current electrolysis unit is short of water, the system will directly read the lower water level sensor of the previous level until it is read that the first-level electrolysis unit is also at the lower water level threshold. The system will replenish water for the first-level electrolysis unit to the upper water level threshold, and then the system enters the electrolysis process. After the electrolysis is completed, the water levels from level N to level 2 are all at the lower water level threshold. The system will read the lower water level sensor of the first-level electrolysis unit and use the water from the first level to replenish the second level until the first-level electrolysis unit reaches the lower water level threshold.

[0054] In the present application, the lower threshold water level sensor of the internal water storage tank is at the bottom of the tank. When the water level reaches the lower threshold, the remaining water in the tank is only enough for the circulating water pump to fill the electrolytic cell and circulate it, so that the electrolytic cell is always kept moist with water to prevent it from drying out and being damaged. Therefore, the setting of the specific lower threshold is determined according to the electrolytic cell capacity of the electrolytic unit in which it is located; the upper threshold water level sensor is placed on the top of the internal water storage tank. For the first-level electrolytic unit, the applicant uses the difference between the upper threshold and the lower threshold to determine the amount of electrolyzed water. For other electrolytic units, the upper threshold will issue an early warning when there is too much water and the system is abnormal, causing the electrolytic device to shut down.

[0055] Example

[0056] The reaction area is 70 cm 2 The MEA is used as the electrolysis carrier, the electrolysis current of a single MEA is 100A, the electrolysis voltage of a single MEA is about 1.8V, the electrolytic cell in the first-stage electrolysis unit uses 250 or more MEAs for electrolysis, the initial deionized water volume for electrolysis is about 125L, the percentage of D atoms in the total H atoms in the deionized water, that is, the ratio of D to H+D, that is, the initial abundance is about 0.0155%, after 10 hours of continuous cyclic electrolysis, the power consumption is about 450 kWh, the water volume after electrolysis is about 25L, and the abundance after electrolysis is about 0.0546%; the second-stage electrolysis unit uses the water after electrolysis in the first-stage electrolysis unit as the water source for electrolysis, uses 50 MEAs, and the average electrolysis power is 9 kW. The electrolysis lasted for 10 hours, consuming 90 kWh of electricity, with 1L of remaining water after electrolysis and an abundance of 0.279% after electrolysis; the third-stage electrolysis unit used the water electrolyzed by the second-stage electrolysis unit as a water source for electrolysis, using 10 MEAs, with an average electrolysis power of 1.8 kW, with a total electrolysis time of 10 hours, consuming 18 kWh of electricity, with 1L of remaining water after electrolysis and an abundance of 1.567% after electrolysis; the fourth-stage electrolysis unit used the water electrolyzed by the third-stage electrolysis unit as a water source for electrolysis, using 2 MEAs, with an average electrolysis power of 0.36 kW, with a total electrolysis time of 10 hours, consuming 3.6 kWh of electricity, with 0.2L of remaining water after electrolysis and an abundance of 90.47% after electrolysis.

[0057] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0058] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A heavy water preparation device, comprising an external water storage unit, an electrolysis unit, an internal water storage unit and a control unit; The electrolysis unit comprises an electrolytic cell, an electrolysis power supply, a cathode-side gas-liquid separator and an anode-side gas-liquid separator; The electrolytic power supply is connected to the electrolytic cell to control the opening and closing of the electrolytic cell; The control unit is connected to the external water storage unit, the electrolysis unit and the internal water storage unit respectively, so as to detect and control the operation of the electrolysis in real time; The outlet of the external water storage unit is connected to the inlet of the internal water storage unit, the liquid outlet of the internal water storage unit is connected to the liquid inlet of the electrolyzer, the liquid outlet of the electrolyzer is connected to the first liquid inlet of the internal water storage unit, the cathode side gas outlet of the electrolyzer is connected to the gas inlet of the cathode side gas-liquid separator, the anode side gas outlet of the electrolyzer is connected to the gas inlet of the anode side gas-liquid separator, and the liquid outlet of the cathode side gas-liquid separator and the liquid outlet of the anode side gas-liquid separator are both connected to the second liquid inlet of the internal water storage unit; The electrolysis units and the internal water storage units are connected in series in several stages according to the above connection method; the internal water storage units of adjacent units are connected.

2. The device according to claim 1, characterized in that A water replenishment pump is arranged between the external water storage unit and the internal water storage unit.

3. The device according to claim 1, characterized in that The electrolysis unit further includes a condenser, which is disposed between the electrolysis tank and the anode-side gas-liquid separator.

4. The device according to claim 1, characterized in that The electrolysis unit is also provided with a temperature sensor, and the temperature sensor is connected to the electrolysis tank.

5. The device according to claim 1, characterized in that A circulating water pump is provided between the internal water storage unit and the electrolytic cell.

6. The device according to claim 1, characterized in that The several levels are 3 to 4 levels.

7. The device according to claim 1, characterized in that The electrolytic cell is a solid polymer electrolyte water electrolysis device, and the membrane electrodes in the electrolytic cell are connected in series and / or in parallel.

8. A method for preparing heavy water using the device according to any one of claims 1 to 7, comprising the following steps: A) adding water from the external water storage unit to the primary internal water storage unit until the water level of the primary internal water storage unit reaches an upper threshold value, and the control unit controls the primary electrolysis unit to perform electrolysis; B) the oxygen and hydrogen generated in the electrolytic cell of the primary electrolysis unit enter the anode side gas-liquid separator and the cathode side gas-liquid separator respectively, and the separated water enters the primary internal water storage unit again for electrolysis again and then enters the primary internal water storage unit; C) replenishing the water of the primary internal water storage unit obtained in step B) to the secondary internal water storage unit, and when the water of the primary internal water storage unit is lower than the lower limit threshold, the replenishment ends, the secondary electrolysis unit starts electrolysis, and step B) is repeated; The water in the first-level internal water storage unit is replenished to the upper water level threshold before electrolysis begins; and the water obtained after each level of electrolysis unit completes electrolysis is replenished to the next level until each level of electrolysis unit performs electrolysis.

9. The method according to claim 8, characterized in that When the internal water storage unit is 4 levels, the number of membrane electrodes of the first-level electrolysis unit is greater than the number of membrane electrodes of the second-level electrolysis unit, which is greater than the number of membrane electrodes of the third-level electrolysis unit, which is greater than the number of membrane electrodes of the fourth-level electrolysis unit.

10. The method according to claim 8, characterized in that When the temperature of the electrolytic cell is higher than 50°C, the condenser is started to cool down.

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