Method for producing hydrogen by electrolyzing water

Abstract

The invention relates to a method for producing hydrogen by electrolyzing water, which comprises the following steps: electrolyzing water in an electrolytic bath; enabling a cathode product to enter a hydrogen cooler for heat exchange with a cooling medium, and then entering a hydrogen washing tower for separation treatment; the anode product enters an oxygen cooler for heat exchange with a cooling medium and then enters an oxygen washing tower for separation treatment; a tower kettle of the hydrogen washing tower is provided with a first gas raising tower tray and a first downcomer; a first filler layer is arranged in the oxygen washing tower; a first gas-liquid separation device is arranged at the top of the oxygen washing tower; a tower kettle of the oxygen washing tower is provided with a second gas raising tower tray and a second downcomer; a second filler layer is arranged in the oxygen washing tower; and a second gas-liquid separation device is arranged at the top of the oxygen washing tower. According to the method, equipment optimization is effectively achieved, energy consumption is low, alkali liquor carried in hydrogen and oxygen can be effectively separated, the technological process is simple, overall operation safety and stability are high, and prepared hydrogen and oxygen products are high in purity.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen production by electrolysis of water, and in particular to a method for hydrogen production by electrolysis of water. Background Art

[0002] Gas-liquid separation is a key step in the process of hydrogen production by electrolysis of water. At present, the conventional gas-liquid separation method in the process of hydrogen production by electrolysis of water is to send the two-phase flow of hydrogen and alkali obtained from the cathode gas collecting pipe of the electrolyzer into the hydrogen separator, and send the two-phase flow of oxygen and alkali obtained from the anode gas collecting pipe into the oxygen separator, separate the alkali by gravity sedimentation, and then send them to the hydrogen cooler and oxygen cooler for cooling, and then send them to the hydrogen scrubber and oxygen scrubber respectively. After washing and cooling, hydrogen and oxygen are obtained and sent to the subsequent system. However, the above method cannot effectively separate the alkali entrained in oxygen and hydrogen, and the separation efficiency is poor. In addition, the alkali in the subsequent hydrogen (oxygen) separator is mixed using the principle of a coupling device and then returned to the electrolyzer, which easily causes hydrogen and oxygen to mix, posing a safety hazard. Summary of the invention

[0003] The purpose of the present invention is to provide a method for producing hydrogen by electrolysis of water. The method provided by the present invention effectively realizes equipment optimization and has low energy consumption, can effectively separate alkali solution entrained in hydrogen and oxygen, has a simple process flow and high overall operation safety and stability, and the prepared hydrogen and oxygen products have high purity.

[0004] In order to achieve the above object, the present invention provides a method for producing hydrogen by electrolysis of water, wherein the method comprises: electrolyzing water in an electrolytic cell to obtain an anode product from an anode side and a cathode product from a cathode side; The cathode product enters a hydrogen cooler to exchange heat with a cooling medium to obtain a cathode product after heat exchange; the cathode product enters a hydrogen scrubbing tower to be separated and treated to obtain a mixture of hydrogen and a first alkali solution; The anode product enters an oxygen cooler to exchange heat with a cooling medium to obtain an anode product after heat exchange; the anode product after heat exchange enters an oxygen scrubber to be separated and treated to obtain a mixture of oxygen and a second alkali solution; The tower kettle of the hydrogen washing tower is provided with a first gas-rising tray and a first downcomer; the tower of the oxygen washing tower is provided with a first packing layer; the tower top of the oxygen washing tower is provided with a first gas-liquid separation device; The oxygen washing tower has a second gas-rising tray and a second downcomer in the tower bottom; a second packing layer in the tower of the oxygen washing tower; and a second gas-liquid separation device at the top of the oxygen washing tower.

[0005] Optionally, the method further comprises: allowing the cathode product after heat exchange to enter the first packing layer through the first gas lifting tray to contact with hydrogen-side desalted water, and then enter the first gas-liquid separation device for gas-liquid separation treatment to obtain the hydrogen and the first alkali liquid mixture; The anode product after heat exchange enters the second packing layer through the second gas lifting tray to contact with oxygen-side desalted water, and then enters the second gas-liquid separation device for gas-liquid separation treatment to obtain the oxygen and the second alkali solution mixture.

[0006] Optionally, the method further comprises: a. allowing the first alkali solution mixture to enter the kettle of the hydrogen scrubbing tower through the first downcomer; b. Feeding the first alkali solution mixture into a first alkali solution circulation pump and an alkali solution cooler in sequence for pressurized cooling to obtain a first alkali solution mixture after pressurized cooling, and returning the first alkali solution mixture after pressurized cooling to the electrolytic cell; The outlet pressure of the first alkali solution circulation pump is 1.8-2.0 MPa; the temperature of the first alkali solution mixture after pressurized cooling is 70-75°C.

[0007] Optionally, the method further comprises: a. allowing the second alkali solution mixture to enter the kettle of the oxygen washing tower through the second downcomer; b. Feeding the second alkali liquid mixture into a second alkali liquid circulation pump and an alkali liquid cooler in sequence for pressurized cooling to obtain a second alkali liquid mixture after pressurized cooling, and returning the second alkali liquid mixture after pressurized cooling to the electrolytic cell; The outlet pressure of the second alkali solution circulation pump is 1.8-2.0 MPa; the temperature of the second alkali solution mixture after pressurized cooling is 70-75°C.

[0008] Optionally, the method further comprises: controlling the pressure of oxygen in the oxygen outlet pipeline and the pressure of hydrogen in the hydrogen outlet pipeline using a pressure control element; Among them, the pressure of oxygen in the oxygen outlet pipeline is 1.5~1.8MPaG; the pressure of hydrogen in the hydrogen outlet pipeline is 1.5~1.8MPaG.

[0009] Optionally, the type of filler in the first packing layer is selected from one or more of step ring packing, ball ring packing and structured packing; Optionally, the type of filler in the second packing layer is selected from one or more of step ring packing, ball ring packing and structured packing.

[0010] The first gas-liquid separation device and the second gas-liquid separation device are each independently selected from a baffled gas-liquid separator and / or a wire mesh demister.

[0011] Optionally, the operating temperature of the hydrogen scrubbing tower is 50-55° C., and the operating pressure is 1.5-1.7 MPaG.

[0012] Optionally, the operating temperature of the oxygen scrubbing tower is 50-55° C., and the operating pressure is 1.5-1.7 MPaG.

[0013] Optionally, when the oxygen purity is above 98.5%, the oxygen is allowed to enter the oxygen purification device through the oxygen side pressure three-way valve, and when the oxygen purity is below 98.5%, the oxygen is allowed to be discharged into the atmosphere through the oxygen side pressure three-way valve; When the purity of the hydrogen is above 99.8%, the hydrogen is allowed to enter the oxygen purification device through the hydrogen side pressure three-way valve. When the purity of the hydrogen is below 99.8%, the hydrogen is allowed to be discharged into the atmosphere through the hydrogen side pressure three-way valve.

[0014] Through the above technical scheme, the present invention uses a hydrogen (oxygen) washing tower to replace the hydrogen (oxygen) separator, hydrogen (oxygen) gas scrubber and final cooler, effectively realizing equipment optimization; the tower kettle of the hydrogen (oxygen) washing tower is provided with a gas-raising tower plate and a downcomer, so that the hydrogen (oxygen) is completely separated from the downcomer on the tower when separating from the alkali liquid, and the gas-liquid separator is used as the tower top demister at the top of the tower to ensure the water content and alkali content of the gas out of the tower. The system and method provided by the present invention effectively realize equipment optimization, low energy consumption, can effectively separate the alkali liquid entrained in hydrogen and oxygen, the process flow is simple, and the overall operation safety and stability are high, and the prepared hydrogen and oxygen products are of high purity.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 This is a schematic diagram of the process flow of Example 1 of the present invention.

[0017] Description of Reference Numerals 1. Hydrogen scrubbing tower; 2. Oxygen scrubbing tower; 3. Hydrogen cooler; 4. Oxygen cooler; 5. First alkali solution circulation pump; 6. Second alkali solution circulation pump; 7. Electrolyzer; 8. Alkali solution cooler; 9. Hydrogen purification device; 10. Oxygen purification device.

[0018] 1-1, hydrogen safety valve; 1-2, first hydrogen side pressure regulating valve; 1-3, second hydrogen side pressure regulating valve; 1-4, hydrogen side pressure three-way valve; 1-5, hydrogen side desalted water regulating valve; 1-6, hydrogen scrubber liquid level regulating valve A; 1-7, hydrogen scrubber liquid level regulating valve B; 1-8, first gas-liquid separation device; 1-9, first gas riser tray; 1-10, first downcomer.

[0019] 2-1, oxygen safety valve; 2-2, first oxygen side pressure regulating valve; 2-3, second oxygen side pressure regulating valve; 2-4, oxygen side pressure three-way valve; 2-5, oxygen side desalted water regulating valve; 2-6, oxygen washing tower liquid level regulating valve A; 2-7, oxygen washing tower liquid level regulating valve B; 2-8, second gas-liquid separation device; 2-9, second riser tray; 2-10, second downcomer.

[0020] 5-1, inlet valve of the first alkali liquid circulation pump; 5-2, inlet filter of the first alkali liquid circulation pump; 5-3, outlet pressure gauge of the first alkali liquid circulation pump; 5-4, outlet check valve of the first alkali liquid circulation pump; 5-5, outlet valve of the first alkali liquid circulation pump; 5-6, alkali liquid check valve on the hydrogen side; 6-1. Inlet valve of the second alkali liquid circulation pump; 6-2. Inlet filter of the second alkali liquid circulation pump; 6-3. Outlet pressure gauge of the second alkali liquid circulation pump; 6-4. Outlet check valve of the second alkali liquid circulation pump; 6-5. Outlet valve of the second alkali liquid circulation pump; 6-6. Oxygen side alkali liquid check valve. DETAILED DESCRIPTION

[0021] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0022] The present disclosure provides a method for producing hydrogen by electrolyzing water, wherein the method comprises: electrolyzing water in an electrolytic cell to obtain an anode product from an anode side and a cathode product from a cathode side; The cathode product enters a hydrogen cooler to exchange heat with a cooling medium to obtain a cathode product after heat exchange; the cathode product enters a hydrogen scrubbing tower to be separated and treated to obtain a mixture of hydrogen and a first alkali solution; The anode product enters an oxygen cooler to exchange heat with a cooling medium to obtain an anode product after heat exchange; the anode product after heat exchange enters an oxygen scrubber to be separated and treated to obtain a mixture of oxygen and a second alkali solution; The tower kettle of the hydrogen washing tower is provided with a first gas-rising tray and a first downcomer; the tower of the oxygen washing tower is provided with a first packing layer; the tower top of the oxygen washing tower is provided with a first gas-liquid separation device; The oxygen washing tower has a second gas-rising tray and a second downcomer in the tower bottom; a second packing layer in the tower of the oxygen washing tower; and a second gas-liquid separation device at the top of the oxygen washing tower.

[0023] The present disclosure uses a hydrogen (oxygen) scrubber to replace a hydrogen (oxygen) separator, a hydrogen (oxygen) gas scrubber and a final cooler, effectively realizing equipment optimization; the tower kettle of the hydrogen (oxygen) scrubber is provided with a gas-raising tray and a downcomer, so that the hydrogen (oxygen) is completely separated from the downcomer on the tower when separating from the alkali solution, and the gas-liquid separator is used at the top of the tower as a tower top demister to ensure the water content and alkali content of the gas out of the tower. The system and method provided by the present disclosure effectively realize equipment optimization, low energy consumption, can effectively separate the alkali solution entrained in hydrogen and oxygen, the process flow is simple, and the overall operation safety and stability are high, and the prepared hydrogen and oxygen products are of high purity.

[0024] In the present disclosure, the tower diameter, tower height and number of plates of the first gas-raising tray and the second gas-raising tray are designed according to the hydrogen processing amount to obtain corresponding values; the length and inner diameter of the first downcomer and the second downcomer are designed according to the hydrogen processing amount to obtain corresponding values. The tower kettle of the hydrogen (oxygen) washing tower is provided with a gas-raising tray and a downcomer, so that the hydrogen (oxygen) and the alkali liquid are completely separated from the downcomer on the tower when being separated, and the gas-liquid separator is used as the tower top demister at the top of the tower, so that the water content and alkali content of the gas out of the tower are guaranteed, and the alkali liquid entrained in the hydrogen and oxygen can be effectively separated.

[0025] In a specific embodiment, the method further comprises: allowing the cathode product after heat exchange to enter the first packing layer through the first gas lifting tray to contact with hydrogen-side desalted water, and then enter the first gas-liquid separation device for gas-liquid separation treatment to obtain the hydrogen and the first alkali liquid mixture; The anode product after heat exchange enters the second packing layer through the second gas lifting tray to contact with oxygen-side desalted water, and then enters the second gas-liquid separation device for gas-liquid separation treatment to obtain the oxygen and the second alkali solution mixture.

[0026] In a specific implementation, the method further comprises: a. allowing the first alkali solution mixture to enter the kettle of the hydrogen scrubbing tower through the first downcomer; b. Feeding the first alkali solution mixture into a first alkali solution circulation pump and an alkali solution cooler in sequence for pressurized cooling to obtain a first alkali solution mixture after pressurized cooling, and returning the first alkali solution mixture after pressurized cooling to the electrolytic cell; The outlet pressure of the first alkali solution circulation pump is 1.9-2.0 MPa; the temperature of the first alkali solution mixture after pressurized cooling is 70-75°C.

[0027] In a specific implementation, the method further comprises: a. allowing the second alkali solution mixture to enter the kettle of the oxygen washing tower through the second downcomer; b. Feeding the second alkali liquid mixture into a second alkali liquid circulation pump and an alkali liquid cooler in sequence for pressurized cooling to obtain a second alkali liquid mixture after pressurized cooling, and returning the second alkali liquid mixture after pressurized cooling to the electrolytic cell; The outlet pressure of the second alkali solution circulation pump is 1.9-2.0 MPa; the temperature of the second alkali solution mixture after pressurized cooling is 70-75°C.

[0028] In one embodiment, the method further comprises: using a pressure regulating valve to control the pressure of oxygen in the oxygen outlet pipeline The pressure of oxygen in the oxygen pressure control valve is 1.5~1.8MPaG; the pressure of hydrogen in the hydrogen pressure control valve is 1.5~1.8MPaG.

[0029] In a specific embodiment, the type of filler in the first packing layer is selected from one or more of step ring packing, ball ring packing and structured packing, preferably step ring packing; the type of filler in the second packing layer is selected from one or more of step ring packing, ball ring packing and structured packing, preferably step ring packing.

[0030] In a specific embodiment, the first gas-liquid separation device and the second gas-liquid separation device are each selected from a baffled gas-liquid separator and / or a wire mesh demister, preferably a baffled gas-liquid separator.

[0031] In a specific embodiment, the operating temperature of the hydrogen scrubber is 50-55°C and the operating pressure is 1.5-1.7 MPaG; The operating temperature of the oxygen scrubbing tower is 50-55°C, and the operating pressure is 1.5-1.7 MPaG.

[0032] In a specific embodiment, when the oxygen purity is above 98.5%, the oxygen is allowed to enter the oxygen purification device through the oxygen side pressure three-way valve, and when the oxygen purity is below 98.5%, the oxygen is allowed to be discharged into the atmosphere through the oxygen side pressure three-way valve; When the purity of the hydrogen is above 99.8%, the hydrogen is allowed to enter the oxygen purification device through the hydrogen side pressure three-way valve. When the purity of the hydrogen is below 99.8%, the hydrogen is allowed to be discharged into the atmosphere through the hydrogen side pressure three-way valve.

[0033] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0034] Example 1 The process system of this embodiment includes: an electrolytic cell 7, a hydrogen cooler 3, an oxygen cooler 4, a hydrogen scrubber 1, an oxygen scrubber 2, a first alkali liquid circulation pump 5, a second alkali liquid circulation pump 6, an alkali liquid cooler 8, a hydrogen purification device 9 and an oxygen purification device 10; wherein, the tower kettle of the hydrogen scrubber is provided with a first gas-raising tray 1-9 and a first downcomer 1-10; a first packing layer is provided in the tower of the hydrogen scrubber; a first gas-liquid separation device 1-8 is provided at the top of the hydrogen scrubber; a second gas-raising tray 2-9 and a second downcomer 2-10 are provided in the tower kettle of the oxygen scrubber; a second packing layer is provided in the tower of the oxygen scrubber; a second gas-liquid separation device 2-8 is provided at the top of the oxygen scrubber; the packing type in the first packing layer and the packing type in the second packing layer are selected from step ring packing; the first gas-liquid separation device and the second gas-liquid separation device are selected from baffled gas-liquid separators.

[0035] The system also includes a pressure control element PC, a liquid level control element, a hydrogen safety valve 1-1, an oxygen safety valve 2-1, a first hydrogen side pressure regulating valve 1-2, a second hydrogen side pressure regulating valve 1-3, a first oxygen side pressure regulating valve 2-2, a second oxygen side pressure regulating valve 2-3, a hydrogen side desalted water regulating device 1-5 and an oxygen side desalted water regulating device 2-5.

[0036] Process flow chart Figure 1 shown.

[0037] This embodiment provides a method for producing hydrogen by electrolysis of water, and the specific steps are as follows: a. electrolyzing water in an electrolytic cell to obtain an anode product from the anode side and a cathode product from the cathode side; b. Allow the cathode product to enter the hydrogen cooler for heat exchange with the cooling medium to obtain the cathode product after heat exchange; allow the cathode product after heat exchange to enter the hydrogen scrubbing tower, enter the first packing layer through the first gas riser tray to contact with the desalted water on the hydrogen side, and then enter the first gas-liquid separation device for gas-liquid separation treatment to obtain a mixture of hydrogen and the first alkali liquid; when the oxygen purity is above 98.5%, allow the oxygen to enter the oxygen purification device through the oxygen side pressure three-way valve 2-4, and when the oxygen purity is below 98.5%, allow the oxygen to be discharged into the atmosphere through the oxygen side pressure three-way valve 2-4; The first alkali liquid mixture is allowed to enter the kettle of the hydrogen washing tower through the first downcomer; the first alkali liquid mixture is sent to the first alkali liquid circulation pump and the alkali liquid cooler in sequence for pressurized cooling to obtain the first alkali liquid mixture after pressurized cooling, and the first alkali liquid mixture after pressurized cooling is returned to the electrolyzer; wherein, the operating temperature of the hydrogen washing tower is 50-55°C, and the operating pressure is 1.5-1.8MPaG; the outlet pressure of the first alkali liquid circulation pump is 1.8-2.0MPa; the temperature of the first alkali liquid mixture after pressurized cooling is 70-75°C.

[0038] c. Allow the anode product to enter the oxygen cooler for heat exchange with the cooling medium to obtain the anode product after heat exchange; allow the anode product after heat exchange to enter the oxygen washing tower through the second gas-raising tray and enter the second packing layer to contact with the desalted water on the oxygen side, and then enter the second gas-liquid separation device for gas-liquid separation treatment to obtain oxygen and a second alkali liquid mixture; when the hydrogen purity is above 99.8%, allow the hydrogen to enter the oxygen purification device through the hydrogen side pressure three-way valve 1-4, and when the hydrogen purity is below 99.8%, allow the hydrogen to be discharged into the atmosphere through the hydrogen side pressure three-way valve 1-4; The second alkali liquid mixture enters the kettle of the oxygen washing tower through the second downcomer; the second alkali liquid mixture is sequentially sent to the second alkali liquid circulation pump and the alkali liquid cooler for pressurized cooling to obtain the second alkali liquid mixture after pressurized cooling, and the second alkali liquid mixture after pressurized cooling is returned to the electrolytic cell; the operating temperature of the oxygen washing tower is 50-55°C, and the operating pressure is 1.5-1.8MPaG; the outlet pressure of the second alkali liquid circulation pump is 1.8-2.0MPa; the temperature of the second alkali liquid mixture after pressurized cooling is 70-75°C.

[0039] Comparative Example 1 The system and method in Example 1 are used, with the only difference being that the hydrogen (oxygen) scrubbing tower is replaced by a conventional hydrogen (oxygen) separator, hydrogen (oxygen) gas scrubber and final cooler.

[0040] Comparative Example 2 The system and method in Example 1 are used, with the only difference being that no gas lift tray and no downcomer are provided in the hydrogen scrubbing tower; and no gas lift tray and no downcomer are provided in the oxygen scrubbing tower.

[0041] Test Case The purity of hydrogen, the purity of oxygen, the content of alkali liquid entrained in hydrogen and the content of alkali liquid entrained in oxygen in the above embodiments and comparative examples were tested, and the test results are listed in Table 1.

[0042] Among them, the purity of hydrogen is measured according to GB / T 3634.2-2011; Oxygen purity is measured according to GB / T 3863-2008; The content of alkali solution entrained in hydrogen or oxygen is measured using a conventional alkali solution content detector.

[0043] Table 1

[0044] As can be seen from Table 1, by adopting the system and method provided by the present application, a hydrogen (oxygen) scrubbing tower is used instead of a hydrogen (oxygen) separator, a hydrogen (oxygen) gas scrubber and a final cooler, so as to effectively optimize the equipment and effectively reduce the process energy consumption; the tower kettle of the hydrogen (oxygen) scrubbing tower is provided with a gas riser tray and a downcomer, so as to achieve complete separation of the hydrogen (oxygen) from the downcomer when separating the alkali liquid, and effectively separate the alkali liquid entrained in the hydrogen and oxygen. Compared with Comparative Examples 1 and 2, Example 1 of the present application has an effectively reduced alkali liquid content in the hydrogen (oxygen), so that the purity of hydrogen and oxygen is further improved, and the process flow is simple and the overall operation safety and stability are high.

[0045] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0046] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0047] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for producing hydrogen by electrolysis of water, wherein: The method includes: electrolyzing water in an electrolytic cell to obtain an anode product from an anode side and a cathode product from a cathode side; The cathode product enters a hydrogen cooler to exchange heat with a cooling medium to obtain a cathode product after heat exchange; the cathode product enters a hydrogen scrubbing tower to be separated and treated to obtain a mixture of hydrogen and a first alkali solution; The anode product enters an oxygen cooler to exchange heat with a cooling medium to obtain an anode product after heat exchange; the anode product after heat exchange enters an oxygen scrubber to be separated and treated to obtain a mixture of oxygen and a second alkali solution; The tower kettle of the hydrogen scrubbing tower is provided with a first gas-rising tray and a first downcomer; the tower of the hydrogen scrubbing tower is provided with a first packing layer; the tower top of the hydrogen scrubbing tower is provided with a first gas-liquid separation device; The oxygen washing tower has a second gas-rising tray and a second downcomer in the tower bottom; a second packing layer in the tower of the oxygen washing tower; and a second gas-liquid separation device at the top of the oxygen washing tower.

2. The method according to claim 1, wherein: The method further comprises: allowing the cathode product after heat exchange to enter the first packing layer through the first gas lifting tray to contact with hydrogen-side desalted water, and then enter the first gas-liquid separation device for gas-liquid separation treatment to obtain the hydrogen and the first alkali liquid mixture; The anode product after heat exchange enters the second packing layer through the second gas lifting tray to contact with oxygen-side desalted water, and then enters the second gas-liquid separation device for gas-liquid separation treatment to obtain the oxygen and the second alkali solution mixture.

3. The method according to claim 1, wherein: The method further includes: a. allowing the first alkali solution mixture to enter the kettle of the hydrogen scrubbing tower through the first downcomer; b. Feeding the first alkali solution mixture into a first alkali solution circulation pump and an alkali solution cooler in sequence for pressurized cooling to obtain a first alkali solution mixture after pressurized cooling, and returning the first alkali solution mixture after pressurized cooling to the electrolytic cell; The outlet pressure of the first alkali solution circulation pump is 1.8-2.0 MPa; the temperature of the first alkali solution mixture after pressurized cooling is 70-75°C.

4. The method according to claim 1, wherein: The method further includes: a. allowing the second alkali solution mixture to enter the kettle of the oxygen washing tower through the second downcomer; b. Feeding the second alkali liquid mixture into a second alkali liquid circulation pump and an alkali liquid cooler in sequence for pressurized cooling to obtain a second alkali liquid mixture after pressurized cooling, and returning the second alkali liquid mixture after pressurized cooling to the electrolytic cell; The outlet pressure of the second alkali solution circulation pump is 1.8-2.0 MPa; the temperature of the second alkali solution mixture after pressurized cooling is 70-75°C.

5. The method according to claim 1, wherein: The method further comprises: controlling the pressure of oxygen in the oxygen outlet pipeline and the pressure of hydrogen in the hydrogen outlet pipeline using a pressure control element; Among them, the pressure of oxygen in the oxygen outlet pipeline is 1.5~1.8MPaG; the pressure of hydrogen in the hydrogen outlet pipeline is 1.5~1.8MPaG.

6. The method according to claim 1, wherein: The type of filler in the first packing layer is selected from one or more of step ring packing, ball ring packing and structured packing; The type of filler in the second packing layer is selected from one or more of step ring packing, ball ring packing and structured packing.

7. The method according to claim 1, wherein: The first gas-liquid separation device and the second gas-liquid separation device are each independently selected from a baffled gas-liquid separator and / or a wire mesh demister.

8. The method according to claim 1, wherein: The operating temperature of the hydrogen scrubbing tower is 50-55°C, and the operating pressure is 1.5-1.7MPaG.

9. The method according to claim 1, wherein: The operating temperature of the oxygen scrubbing tower is 50-55°C, and the operating pressure is 1.5-1.7 MPaG.

10. The method according to claim 1, wherein: When the oxygen purity is above 98.5%, the oxygen is allowed to enter the oxygen purification device through the oxygen side pressure three-way valve; when the oxygen purity is below 98.5%, the oxygen is allowed to be discharged into the atmosphere through the oxygen side pressure three-way valve; When the purity of the hydrogen is above 99.8%, the hydrogen is allowed to enter the oxygen purification device through the hydrogen side pressure three-way valve. When the purity of the hydrogen is below 99.8%, the hydrogen is allowed to be discharged into the atmosphere through the hydrogen side pressure three-way valve.

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