Alkaline water electrolysis hydrogen production system capable of avoiding electrochemical corrosion and control method

Abstract

The invention relates to the technical field of water electrolysis hydrogen production, and particularly discloses an alkaline water electrolysis hydrogen production system capable of avoiding electrochemical corrosion and a control method. The alkaline water electrolysis hydrogen production system structurally comprises an electrolytic bath, a hydrogen separator, an oxygen separator, an alkali liquor circulating pump, a cooler, a pure water tank, a dilute alkali tank, a concentrated alkali tank, a pure water pump, a filter 1, a filter 2, a control valve 1, a control valve 2, a control valve 3, a control valve 4, a control valve 5, a control valve 6, a control valve 7, a control valve 8, a control valve 9, a flow meter, a thermometer 1, a thermometer 2, a KOH concentration monitor and a KOH micro analyzer. The device comprises a pressure controller 1, a pressure controller 2, a liquid level controller 1, a liquid level controller 2 and a pipeline. The problem of electrochemical corrosion of the precious metal electrode and the multi-element alloy electrode of the alkaline water electrolysis electrolytic bath in a standby state can be solved, and the service life of the electrolytic bath is prolonged; the problems of on-line monitoring and automatic alkali supplement of the alkali liquor of the alkaline water electrolysis hydrogen production system can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of water electrolysis hydrogen production, and in particular to an alkaline water electrolysis hydrogen production system and a control method for avoiding electrochemical corrosion. Background Art

[0002] The water electrolysis hydrogen production process is divided into four technologies according to different electrolytes: alkaline water electrolysis (AWE), proton exchange membrane water electrolysis (PEM), anion exchange membrane water electrolysis (AEM) and solid oxide water electrolysis (SOEC). At present, alkaline water electrolysis and proton exchange membrane water electrolysis have been commercialized, while anion exchange membrane water electrolysis and solid oxide water electrolysis are in the laboratory research and development stage. Alkaline water electrolysis hydrogen production technology is the most mature, with the characteristics of simple electrolyzer structure, long operating life and low price. Alkaline water electrolysis requires 25-30% KOH or NaOH aqueous solution as electrolyte.

[0003] The traditional alkaline water electrolysis system consists of an electrolytic cell, a hydrogen separator, an oxygen separator, an alkali liquid circulation pump, a cooler, a pure water tank, a pure water pump, a control valve, a flow meter, a thermometer, a KOH concentration monitor, a pressure controller, a liquid level controller and related pipelines. The cathode of the electrolytic cell uses Raney Ni as an electrode, and the anode uses a nickel mesh as an electrode. The Raney nickel electrode is a mixture of Ni powder and Al powder in a ratio of 8:2, which is sprayed onto the nickel mesh by plasma spraying. The semi-finished product is then activated in a KOH or NaOH solution to dissolve the Al element, increase the specific surface area of ​​the nickel mesh, and promote catalytic activity. In this material electrolytic cell, the cathode and cathode electrodes are both nickel metal, and there is no electrochemical corrosion problem in the standby state.

[0004] With the development of hydrogen energy, the requirements for water electrolysis hydrogen production equipment are becoming higher and higher. Alkaline electrolytic cells are also being upgraded and are currently developing in the direction of large-scale, lightweight, high-efficiency, and low-cost single cells. These development directions are inseparable from the upgrade of electrodes. The simple Raney nickel electrode can no longer meet market demand. At present, some scientific research institutions and enterprises are developing precious metal electrodes and multi-element alloy electrodes (generally used for cathodes). Precious metal electrodes are made by brushing a layer of precious metal platinum or iridium on the surface of the nickel mesh. Multi-element alloy electrodes are made by spraying nickel, aluminum, cobalt, molybdenum, zinc, iron and other two or more metal elements on the surface of the nickel mesh to improve the catalytic activity of electrolysis.

[0005] After testing, it was found that precious metal electrodes and multi-element alloy electrodes can indeed improve the catalytic activity of electrolysis, increase the current density of the electrolyzer, improve the electrolysis efficiency, and reduce the power consumption of electrolysis. However, this also gave rise to a new problem. The newly added metal elements, precious metals such as platinum and iridium, and other metals such as cobalt, molybdenum, zinc, and iron, are different from the activity of metal nickel. When the electrolyzer of the traditional alkaline water electrolysis hydrogen production system is on standby, there is a 30% KOH solution in the electrolyzer as an electrolyte. These metal elements and metal nickel will produce a primary cell reaction, electrochemical corrosion will occur, corrode the nickel element, and reduce the service life of the electrode.

[0006] Therefore, it is necessary to provide an alkaline water electrolysis hydrogen production system and control method that avoids electrochemical corrosion, so as to solve the electrochemical corrosion problem of precious metal and multi-element alloy electrodes in alkaline water electrolysis in standby state. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes an alkaline water electrolysis hydrogen production system and a control method that avoids electrochemical corrosion, so as to solve the electrochemical corrosion problem of precious metal and multi-element alloy electrodes in alkaline water electrolysis in standby state.

[0008] A first aspect of the present invention provides an alkaline water electrolysis hydrogen production system that avoids electrochemical corrosion.

[0009] Specifically, the alkaline water electrolysis hydrogen production system includes the following structures: an electrolyzer, a hydrogen separator, an oxygen separator, an alkali liquid circulation pump, a cooler, a pure water tank, a dilute alkali tank, a concentrated alkali tank, a pure water pump, a filter 1, a filter 2, a control valve 1, a control valve 2, a control valve 3, a control valve 4, a control valve 5, a control valve 6, a control valve 7, a control valve 8, a control valve 9, a flow meter, a thermometer 1, a thermometer 2, a KOH concentration monitor, a KOH trace analyzer, a pressure controller 1, a pressure controller 2, a liquid level controller 1, a liquid level controller 2, and a pipeline.

[0010] Preferably, the electrolytic cell is an alkaline electrolytic cell.

[0011] Preferably, the alkaline electrolytic cell consists of an electrolysis chamber.

[0012] Preferably, the electrolysis chamber is composed of a bipolar plate, a cathode, an anode, and a diaphragm.

[0013] Preferably, the material of the bipolar plate includes nickel-plated carbon steel.

[0014] Preferably, the material of the cathode includes any one of Raney nickel, multi-element alloy electrode and noble metal electrode.

[0015] Preferably, the multi-element alloy electrode is a nickel mesh coated with a metal material.

[0016] Preferably, the metal material includes 3 to 4 of nickel, aluminum, cobalt, molybdenum, zinc and iron.

[0017] Preferably, the noble metal electrode is a layer of noble metal coated on the surface of a nickel mesh.

[0018] Preferably, the noble metal includes any one of platinum and iridium.

[0019] Preferably, the material of the anode includes any one of a pure nickel mesh and a multi-element alloy electrode.

[0020] Preferably, the diaphragm includes at least one of a polyphenylene sulfide diaphragm, a composite diaphragm, and an ion membrane.

[0021] Preferably, the alkaline electrolytic cell comprises 25-30% KOH electrolyte or 25-30% NaOH electrolyte.

[0022] A second aspect of the present invention provides a control method for an alkaline water electrolysis hydrogen production system to avoid electrochemical corrosion.

[0023] Specifically, the following steps are included:

[0024] (1) After the electrolytic cell is shut down, the KOH concentration monitor shows 28-30%. When there is no plan to start the electrolytic cell, the operator starts the system safety mode;

[0025] (2) After the safety mode is started, the system will automatically open control valve 4, close control valve 6, start the alkali liquid circulation pump, and pump the alkali liquid in the system to the concentrated alkali tank. After the hydrogen separator and oxygen separator are emptied, open control valve 7, close control valve 5, and pump the alkali liquid in the electrolytic cell body to the concentrated alkali tank; after the alkali liquid in the electrolytic cell body is emptied, stop the alkali liquid circulation pump, close control valve 4, and close control valve 7;

[0026] (3) After the alkali solution in the system is drained, open control valve 5, open control valve 6, open control valve 8, start the pure water pump, and inject dilute alkali into the system. When the readings of liquid level controller 1 and liquid level controller 2 reach 50-60% of the liquid level respectively, stop the pure water pump;

[0027] (4) Start the alkali solution circulation pump, and the system circulates for 1 to 2 hours. Stop the alkali solution circulation pump. During the circulation period, control the liquid level controller 1 and the liquid level controller 2 at 50 to 60% liquid level. When the liquid level is lower than 50%, start the pure water pump to inject dilute alkali into the system;

[0028] (5) Open control valve 3, close control valve 6, start the alkali solution circulation pump, pump the liquid in the system to the diluted alkali tank, and after the hydrogen separator and oxygen separator are emptied, open control valve 7 to pump the liquid in the electrolytic cell body to the diluted alkali tank; after the liquid in the electrolytic cell body is emptied, stop the alkali solution circulation pump, close control valve 3, and close control valve 7;

[0029] (6) After the alkali solution in the system is drained, open control valve 6, open control valve 9, close control valve 8, start the pure water pump, and inject pure water into the system. When the readings of liquid level controller 1 and liquid level controller 2 both reach 50-60% of the liquid level, stop the pure water pump;

[0030] (7) Repeat steps (4), (5) and (6) to replace the system with pure water 2 to 3 times;

[0031] (8) When the KOH content is less than 100 ppm, the system is in a safe state;

[0032] (9) Upon receiving the power-on command, the operator starts the system power-on preparation mode;

[0033] (10) After the system is started in the preparatory mode, the system repeats step (5) to discharge the system liquid into the diluted alkali tank;

[0034] (11) After the system liquid is drained, open control valve 2, open control valve 6, and switch the KOH micro analyzer to the KOH concentration monitor;

[0035] (12) Start the alkali solution circulation pump to pump concentrated alkali into the system. When the readings of the liquid level controller 1 and the liquid level controller 2 reach 50-60% of the liquid level, stop the alkali solution circulation pump;

[0036] (13) Close control valve 2, open control valve 5, start the alkaline circulation pump, and circulate the system for 1 to 2 hours until the KOH concentration monitor shows a stable reading;

[0037] (14) When the KOH concentration is less than 28%, the concentrated alkali tank is replenished with alkali solution, and steps (12) and (13) are repeated. When the KOH concentration monitor shows a value between 28% and 30%, the alkali replenishment is stopped, the system startup preparation mode ends, and the normal startup procedure of the electrolytic cell is entered;

[0038] (15) During the normal operation of the system, when the KOH concentration is less than 28%, the system water supply is switched from pure water to diluted alkali, the control valve 8 is opened, and the control valve 9 is closed. When the KOH concentration reaches 30%, the system water supply is switched from diluted alkali to pure water, the control valve 9 is opened, and the control valve 8 is closed;

[0039] (16) Repeat step 15) to gradually consume the diluted alkali in the diluted alkali tank.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] The invention can solve the electrochemical corrosion problem of the noble metal electrode and the multi-element alloy electrode of the alkaline water electrolysis cell in the standby state, prolong the life of the electrolysis cell; and solve the problem of online monitoring and automatic alkali replenishment of alkali solution in the alkaline water electrolysis hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of an alkaline water electrolysis hydrogen production system for avoiding electrochemical corrosion according to Example 1 of the present invention;

[0043] Figure 2 Schematic diagram of the conventional alkaline water electrolysis hydrogen production system for comparative example 1. DETAILED DESCRIPTION

[0044] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0045] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0046] Example 1

[0047] An alkaline water electrolysis hydrogen production system to avoid electrochemical corrosion comprises the following structure:

[0048] (1) Electrolyzer, hydrogen separator, oxygen separator, alkali circulation pump, cooler, pure water tank, dilute alkali tank, concentrated alkali tank, pure water pump, filter 1, filter 2, control valve 1, control valve 2, control valve 3, control valve 4, control valve 5, control valve 6, control valve 7, control valve 8, control valve 9, flow meter, thermometer 1, thermometer 2, KOH concentration monitor, KOH micro analyzer, pressure controller 1, pressure controller 2, liquid level controller 1, liquid level controller 2, pipeline. The structural diagram of the system is shown in the figure below. Figure 1 shown.

[0049] (2) The electrolyzer is an alkaline electrolyzer, and the gas production capacity of the alkaline water electrolysis hydrogen production system can reach 8Nm 3 / h, adopts circular pressure design, 40 electrolytic chambers, electrolytic cell design voltage 80V, design current 500A, design current density 5000A / m 2 , the electrolytic cell plate diameter is 486mm, the diaphragm diameter is 408mm, and the electrode diameter is 392mm. Each electrolytic cell consists of a bipolar plate, a cathode, an anode, and a diaphragm. The bipolar plate is made of carbon steel plated with nickel, the anode is made of pure nickel mesh (wire diameter 0.25mm, 46 mesh twill weave), the cathode is a ternary alloy electrode (the base material is a nickel mesh with a wire diameter of 0.25mm, 46 mesh twill weave, plasma sprayed with nickel, aluminum, and molybdenum catalysts, and activated in 25-30% KOH solution), and the diaphragm is a polyphenylene sulfide diaphragm.

[0050] (3) The electrolyte of the electrolytic cell adopts 30% KOH solution. KOH is used as the electrolytic medium and can be recycled without being consumed.

[0051] (4) The electrolyzer is powered by electricity from the grid, or by wind power or photovoltaic power.

[0052] (5) The cathode of the electrolytic cell generates hydrogen, and the anode generates oxygen. The generated hydrogen and the circulating alkali solution are separated in the hydrogen separator. After preliminary separation, the hydrogen is sent to the downstream through the regulating valve of the pressure controller 1, and the pressure of the hydrogen separator is controlled by the pressure controller 1; the generated oxygen and the circulating alkali solution are separated in the oxygen separator, and are sent to the downstream through the regulating valve of the pressure controller 2, and the pressure of the oxygen separator is controlled by the pressure controller 2.

[0053] (6) Thermometer 1 and Thermometer 2 monitor the outlet temperature of the electrolytic cell and control it at 85±5℃ through the cooler.

[0054] (7) The KOH content of the system is monitored by a KOH concentration monitor and a KOH micro-analyzer. Under normal conditions, it is monitored by the KOH concentration monitor. When the KOH concentration monitor shows a value less than 1%, it is switched to the KOH micro-analyzer.

[0055] (8) The pure water tank, control valve 9 and pure water pump constitute a water replenishment system, which is controlled by liquid level controller 1 and liquid level controller 2. The liquid levels of the hydrogen separator and the oxygen separator are controlled at 50±5% by the water replenishment system.

[0056] (9) After the alkali liquid separated by the hydrogen separator and the oxygen separator are combined, they return to the electrolytic cell through the control valve 5, the alkali liquid circulation pump, the control valve 6, the cooler and the flow meter. The alkali liquid circulation pump provides power, and the flow rate of the alkali liquid circulation pump is controlled by the flow meter and the control valve 6.

[0057] (10) The dilute alkali tank, filter 1, control valve 8, control valve 1, control valve 3 and the concentrated alkali tank, filter 2, control valve 2, control valve 4, and alkali circulation pump constitute an alkali replacement unit of the electrolytic cell system. The alkali of the electrolytic cell system can be pumped out to the concentrated alkali tank and the dilute alkali tank through the alkali circulation pump, and the alkali in the concentrated alkali tank and the dilute alkali tank can also be pumped back to the electrolytic cell system through the alkali circulation pump.

[0058] A control method for an alkaline water electrolysis hydrogen production system to avoid electrochemical corrosion, the specific steps are as follows:

[0059] (1) When the operator receives a shutdown command for the alkaline electrolyzer system, the KOH concentration monitor shows 30%, and there is no plan to start the electrolyzer in a short time, the operator starts the system safety mode.

[0060] (2) After the safety mode is started, the system will automatically open control valve 4, close control valve 6, start the alkali liquid circulation pump, and pump the alkali liquid in the system to the concentrated alkali tank. After the hydrogen separator and oxygen separator are emptied, open control valve 7, close control valve 5, and pump the alkali liquid in the electrolytic cell body to the concentrated alkali tank. After the alkali liquid in the electrolytic cell body is emptied, stop the alkali liquid circulation pump, close control valve 4, and close control valve 7.

[0061] (3) After the alkali liquid in the system is drained, open control valve 5, open control valve 6, open control valve 8, start the pure water pump, and inject dilute alkali into the system. When the readings of liquid level controller 1 and liquid level controller 2 both reach 50% liquid level, stop the pure water pump.

[0062] (4) Start the alkali solution circulation pump, circulate the system for 2 hours, and then stop the alkali solution circulation pump. During the circulation period, control the liquid level controller 1 and the liquid level controller 2 at the 50% liquid level. After the KOH concentration monitor reading is stable, stop the alkali circulation pump.

[0063] (5) Open control valve 3, close control valve 6, start the alkali liquid circulation pump, pump the liquid in the system to the diluted alkali tank, and after the hydrogen separator and oxygen separator are emptied, open control valve 7 to pump the liquid in the electrolytic cell body to the diluted alkali tank. After the liquid in the electrolytic cell body is emptied, stop the alkali liquid circulation pump, close control valve 3, and close control valve 7.

[0064] (6) After the alkali liquid in the system is drained, open control valve 6, open control valve 9, close control valve 8, start the pure water pump, and inject pure water into the system. When the readings of liquid level controller 1 and liquid level controller 2 both reach 50% liquid level, stop the pure water pump.

[0065] (7) Repeat steps (4), (5) and (6), replacing the system with pure water twice until the KOH content in the system is less than 100 ppm (when the KOH concentration monitor shows less than 1%, switch to the KOH micro-analyzer).

[0066] (8) When the KOH content is less than 100 ppm, the system is in a stable and safe state. Even though the cathode and anode metals have different reactivities and there is a potential difference, there is no KOH ion as an electrolyte and a circuit cannot be formed, thus avoiding the problem of electrochemical corrosion of the electrodes in the standby state.

[0067] (9) After receiving the power-on command, the operator starts the system power-on preparation mode.

[0068] (10) After the system is started in the preparation mode, the system repeats step (5) to drain the system liquid into the diluted alkali tank.

[0069] (11) After the system liquid is drained, open control valve 2, open control valve 6, and switch the KOH micro-analyzer to the KOH concentration monitor.

[0070] (12) Start the alkali solution circulation pump to pump concentrated alkali into the system until the readings of liquid level controller 1 and liquid level controller 2 both reach 50% liquid level (when the concentrated alkali tank is insufficient, add alkali from the outside), then stop the alkali solution circulation pump.

[0071] (13) Close control valve 2, open control valve 5, start the alkaline circulation pump, and circulate the system for 1 hour until the KOH concentration monitor reading stabilizes.

[0072] (14) If the KOH concentration is less than 28%, add high-concentration alkali solution to the concentrated alkali tank and repeat steps (12) and (13) until the KOH concentration monitor shows 30%. Stop adding alkali, end the system startup preparation mode, and enter the normal startup procedure of the electrolytic cell.

[0073] (15) During the normal operation of the system, if the KOH concentration is less than 28%, the system water supply is switched from pure water to diluted alkali, that is, control valve 8 is opened and control valve 9 is closed. When the KOH concentration reaches 30%, the system water supply is switched from diluted alkali to pure water, that is, control valve 9 is opened and control valve 8 is closed.

[0074] (16) Repeat step (15) to gradually consume the diluted alkali in the diluted alkali tank.

[0075] Comparative Example 1

[0076] A conventional alkaline water electrolysis hydrogen production system.

[0077] (1) Electrolyzer, hydrogen separator, oxygen separator, alkali liquid circulation pump, cooler, pure water tank, pure water pump, control valve 1, control valve 2, flow meter, thermometer 1, thermometer 2, KOH concentration monitor, pressure controller 1, pressure controller 2, liquid level controller 1, liquid level controller 2, pipeline. The structural diagram of the system is shown in the figure below. Figure 2 shown.

[0078] (2) The electrolyzer is an alkaline electrolyzer, and the gas production capacity of the alkaline water electrolysis hydrogen production system can reach 8Nm 3 / h, the electrolytic cell adopts the same design as in Example 1, adopts a circular pressure design, 40 electrolytic chambers, the electrolytic cell design voltage is 80V, the design current is 500A, and the design current density is 5000A / m 2 , the electrolytic cell plate diameter is 486mm, the diaphragm diameter is 408mm, and the electrode diameter is 392mm. Each electrolytic cell consists of a bipolar plate, a cathode, an anode, and a diaphragm. The bipolar plate is made of carbon steel plated with nickel, the anode is made of pure nickel mesh (wire diameter 0.25mm, 46 mesh twill weave), the cathode is a ternary alloy electrode (the base material is a nickel mesh with a wire diameter of 0.25mm, 46 mesh twill weave, plasma sprayed with nickel, aluminum, and molybdenum catalysts, and activated in 25-30% KOH solution), and the diaphragm is a polyphenylene sulfide diaphragm.

[0079] Performance testing:

[0080] The systems of Example 1 and Comparative Example 1 were respectively verified in operation practice under the conditions of an operating pressure of 1.6 MPa and an operating temperature of 85±5°C.

[0081] The system of Example 1 was run for a total of 3 days (the first day, the second day and the eighth day). The operation mode was daytime operation (8:00-18:00) and night standby (18:00-8:00). After each shutdown, the system was switched to the safe mode according to Example 1, and the system was switched to the startup preparation mode before each startup. The data collected during the operation are shown in Tables 1 to 3.

[0082] The comparative example 1 system was operated for a total of 3 days (the first day, the second day and the eighth day). The operation mode was daytime operation (8:00-18:00) and standby at night (18:00-8:00). After each shutdown, the system was in normal standby. The data collected during the operation are shown in Tables 4-6.

[0083] Table 1: First day operation data of the system in Example 1

[0084]

[0085]

[0086] Table 2: Second day operation data of the system in Example 1

[0087]

[0088]

[0089] Table 3: Operation data of the system on the third day of Example 1

[0090]

[0091]

[0092] Table 4 Comparative Example 1 System First Day Operation Data

[0093]

[0094]

[0095] Table 5 Comparative Example 1 System Operation Data for the Second Day

[0096]

[0097] Table 6 Comparative Example 1 System Eighth Day Operation Data

[0098]

[0099] Through practical data verification, in the system of Example 1, during 8 days, the electrolyzer was under the same operating conditions (pressure 1.6MPa, temperature 85±5°C), and the electrolyzer current was always 540A (current density 5400A / m 2 ) and the DC power consumption is 4.8kWh / Nm 3 It can be concluded that the electrode has no obvious electrochemical corrosion and no obvious attenuation.

[0100] Comparative Example 1 During the 8-day period, the electrolyzer was operated under the same operating conditions (pressure 1.6 MPa, temperature 85 ± 5 ° C), at a voltage of 80 V, and the electrolyzer current was 541.6 A (current density 5446 A / m 2 ), and the next day it dropped to 539.0A (current density 5390A / m 2 ), and on the eighth day it dropped to 530.7A (current density 5307A / m 2 ), it was concluded that the electrode underwent electrochemical corrosion and the electrode decayed by 2.0%.

[0101] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution obtained by any modification, equivalent replacement, improvement, etc. made by a person skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection determined by the claims.

Claims

1. An alkaline water electrolysis hydrogen production system to avoid electrochemical corrosion, characterized in that: The alkaline water electrolysis hydrogen production system includes the following structures: an electrolyzer, a hydrogen separator, an oxygen separator, an alkali liquid circulation pump, a cooler, a pure water tank, a dilute alkali tank, a concentrated alkali tank, a pure water pump, a filter 1, a filter 2, a control valve 1, a control valve 2, a control valve 3, a control valve 4, a control valve 5, a control valve 6, a control valve 7, a control valve 8, a control valve 9, a flow meter, a thermometer 1, a thermometer 2, a KOH concentration monitor, a KOH micro-analyzer, a pressure controller 1, a pressure controller 2, a liquid level controller 1, a liquid level controller 2, and a pipeline.

2. The alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The electrolytic cell is an alkaline electrolytic cell.

3. The alkaline water electrolysis hydrogen production system according to claim 2, characterized in that: The alkaline electrolytic cell consists of an electrolysis chamber.

4. The alkaline water electrolysis hydrogen production system according to claim 3, characterized in that: The electrolysis chamber is composed of a bipolar plate, a cathode, an anode and a diaphragm.

5. The alkaline water electrolysis hydrogen production system according to claim 4, characterized in that: The material of the bipolar plate includes nickel-plated carbon steel.

6. The alkaline water electrolysis hydrogen production system according to claim 4, characterized in that: The material of the cathode includes any one of Raney nickel, multi-element alloy electrode and noble metal electrode.

7. The alkaline water electrolysis hydrogen production system according to claim 4, characterized in that: The material of the anode includes any one of a pure nickel mesh and a multi-element alloy electrode.

8. The alkaline water electrolysis hydrogen production system according to claim 4, characterized in that: The diaphragm includes at least one of a polyphenylene sulfide diaphragm, a composite diaphragm and an ion membrane.

9. The alkaline water electrolysis hydrogen production system according to claim 2, characterized in that: The alkaline electrolytic cell contains 25-30% KOH electrolyte or 25-30% NaOH electrolyte.

10. A control method for an alkaline water electrolysis hydrogen production system to avoid electrochemical corrosion, characterized in that: The following steps are involved: (1) After the electrolytic cell is shut down, the KOH concentration monitor shows 28-30%. When there is no plan to start the electrolytic cell, the operator starts the system safety mode; (2) After the safety mode is started, the system will automatically open control valve 4, close control valve 6, start the alkali liquid circulation pump, and pump the alkali liquid in the system to the concentrated alkali tank. After the hydrogen separator and oxygen separator are emptied, open control valve 7, close control valve 5, and pump the alkali liquid in the electrolytic cell body to the concentrated alkali tank; after the alkali liquid in the electrolytic cell body is emptied, stop the alkali liquid circulation pump, close control valve 4, and close control valve 7; (3) After the alkali solution in the system is drained, open control valve 5, open control valve 6, open control valve 8, start the pure water pump, and inject dilute alkali into the system. When the readings of liquid level controller 1 and liquid level controller 2 reach 50-60% of the liquid level respectively, stop the pure water pump; (4) Start the alkali solution circulation pump, and the system circulates for 1 to 2 hours. Stop the alkali solution circulation pump. During the circulation period, control the liquid level controller 1 and the liquid level controller 2 at 50 to 60% liquid level. When the liquid level is lower than 50%, start the pure water pump to inject dilute alkali into the system; (5) Open control valve 3, close control valve 6, start the alkali solution circulation pump, pump the liquid in the system to the diluted alkali tank, and after the hydrogen separator and oxygen separator are emptied, open control valve 7 to pump the liquid in the electrolytic cell body to the diluted alkali tank; after the liquid in the electrolytic cell body is emptied, stop the alkali solution circulation pump, close control valve 3, and close control valve 7; (6) After the alkali solution in the system is drained, open control valve 6, open control valve 9, close control valve 8, start the pure water pump, and inject pure water into the system. When the readings of liquid level controller 1 and liquid level controller 2 both reach 50-60% of the liquid level, stop the pure water pump; (7) Repeat steps (4), (5) and (6) to replace the system with pure water 2 to 3 times; (8) When the KOH content is less than 100 ppm, the system is in a safe state; (9) Upon receiving the power-on command, the operator starts the system power-on preparation mode; (10) After the system is started in the preparatory mode, the system repeats step (5) to discharge the system liquid into the diluted alkali tank; (11) After the system liquid is drained, open control valve 2, open control valve 6, and switch the KOH micro analyzer to the KOH concentration monitor; (12) Start the alkali solution circulation pump to pump concentrated alkali into the system. When the readings of the liquid level controller 1 and the liquid level controller 2 reach 50-60% of the liquid level, stop the alkali solution circulation pump; (13) Close control valve 2, open control valve 5, start the alkaline circulation pump, and circulate the system for 1 to 2 hours; (14) When the KOH concentration is less than 28%, the concentrated alkali tank is replenished with alkali solution, and steps (12) and (13) are repeated. When the KOH concentration monitor shows a value between 28% and 30%, the alkali replenishment is stopped, the system startup preparation mode ends, and the normal startup procedure of the electrolytic cell is entered; (15) During the normal operation of the system, when the KOH concentration is less than 28%, the system water supply is switched from pure water to diluted alkali, the control valve 8 is opened, and the control valve 9 is closed. When the KOH concentration reaches 30%, the system water supply is switched from diluted alkali to pure water, the control valve 9 is opened, and the control valve 8 is closed; (16) Repeat step 15) to gradually consume the diluted alkali in the diluted alkali tank.

Images