Temperature cascade control method and device of alkaline electrolyzer and hydrogen production system

Abstract

The embodiment of the present disclosure provides a temperature cascade control method of an alkaline electrolyzer, comprising the following steps: obtaining an actual temperature of alkali liquor at an outlet of the alkaline electrolyzer; based on the actual temperature of the alkali liquor and a set temperature of the alkali liquor, calculating a theoretical flow of the alkali liquor cooled by an alkali liquor cooler by using a fuzzy control algorithm; obtaining an actual flow of the alkali liquor at an outlet of the alkali liquor cooler; and based on the actual flow of the alkali liquor and the theoretical flow of the alkali liquor, controlling a cooling liquid flow of the alkali liquor cooler. By using the fuzzy calculation method, the temperature information is processed by using rules, the ability of processing large lag and nonlinear problems is improved, the corresponding speed and adaptability of the temperature control of the alkaline electrolyzer are improved, the temperature control of the alkaline electrolyzer is smoother, and when the load condition changes greatly, rapid and accurate temperature regulation is realized.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the field of water electrolysis hydrogen production technology, specifically relating to a method, apparatus and hydrogen production system for temperature cascade control of an alkaline electrolyzer. Background Technology

[0002] Alkaline water electrolysis is an important method for producing hydrogen, involving the decomposition of water molecules into hydrogen and oxygen. During this process, an electric current passes through the electrolyte, generating a chemical reaction and producing heat. To ensure electrolysis efficiency and equipment safety, strict temperature control of the electrolyzer is necessary. However, existing temperature control methods suffer from slow response times and poor adaptability, particularly when load conditions vary significantly, making rapid and accurate temperature regulation difficult. Summary of the Invention

[0003] The embodiments disclosed herein aim to at least solve one of the technical problems existing in the prior art, and provide a method, apparatus and hydrogen production system for cascade temperature control of an alkaline electrolyzer.

[0004] An embodiment of the first aspect of this disclosure provides a method for cascade temperature control of an alkaline electrolyzer, comprising the following steps:

[0005] Obtain the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer;

[0006] Based on the actual temperature and set temperature of the alkali solution, a fuzzy control algorithm is used to calculate the theoretical flow rate of the alkali solution after being cooled by the alkali solution cooler.

[0007] Obtain the actual flow rate of alkali solution at the alkali solution outlet of the alkali solution cooler;

[0008] The flow rate of the coolant in the alkali cooler is controlled based on the actual flow rate and the theoretical flow rate of the alkali solution.

[0009] In some embodiments of this disclosure, the step of calculating the theoretical flow rate of the alkali solution after cooling by the alkali solution cooler using a fuzzy control algorithm based on the actual temperature and set temperature of the alkali solution includes:

[0010] Calculate the difference (e) between the actual temperature of the alkali solution and the set temperature of the alkali solution, and the error change rate (Δe);

[0011] The difference (e) and the rate of change of error (Δe) are transformed into a fuzzy set of temperature regulation variables according to the fuzzy rules.

[0012] The fuzzy set of temperature regulation variables is converted into a definite theoretical flow rate of alkali solution.

[0013] In some embodiments of this disclosure, the fuzzy rules include:

[0014] IF e is NB ANDΔe isΔNB THEN u is uPB;

[0015] IF e is NS ANDΔe isΔZ THEN u is uPS;

[0016] IF e is Z ANDΔe isΔZ THEN u is uZ;

[0017] IF e is PS ANDΔe isΔZ THEN u is uNS;

[0018] IF e is PB ANDΔe isΔPB THEN u is uNB;

[0019] Where e is the difference between the actual temperature of the alkali solution and the set temperature of the alkali solution; NB is a large negative deviation, NS is a small negative deviation, and the temperature deviation of NB is less than that of NS; Z is a zero temperature deviation; PS is a small positive deviation, PB is a large positive deviation, and the temperature deviation of PS is greater than that of NS and less than that of PB; Δe is the rate of change of deviation; ΔNB is a large negative rate of change of deviation, ΔNS is a small negative rate of change of deviation, and the rate of decrease of the temperature deviation of ΔNB is greater than that of ΔNS; ΔZ is a constant temperature deviation; ΔPS is a small positive rate of change of deviation, ΔPB is a large positive rate of change of deviation, and the rate of increase of the temperature difference of ΔPB is greater than that of ΔPS; u is the flow rate regulation variable; uNB is a large negative flow rate variable, uNS is a small negative flow rate variable, and the decrease in flow rate of uNB is greater than that of uNS; uZ is a constant flow rate; uPS is a small positive flow rate variable, uPB is a large positive flow rate variable, and the increase in flow rate of uPS is greater than that of uPS.

[0020] In some embodiments of this disclosure, the step of controlling the coolant flow rate of the alkali cooler based on the actual flow rate and the theoretical flow rate of the alkali solution includes:

[0021] Based on the actual and theoretical flow rates of the alkali solution, a PID method is used to control the coolant flow rate of the alkali solution cooler.

[0022] In some embodiments of this disclosure, the step of controlling the coolant flow rate of the alkali cooler using a PID method based on the actual flow rate and the theoretical flow rate of the alkali solution includes:

[0023] If the difference between the actual flow rate and the theoretical flow rate of the alkali solution is greater than the preset difference, the proportional gain Kp is increased.

[0024] If the difference between the actual flow rate and the theoretical flow rate of the alkali solution is less than the preset difference, the proportional-integral gain Ki is increased.

[0025] An embodiment of the second aspect of this disclosure provides a temperature cascade control device for an alkaline electrolyzer, characterized in that it includes a main controller, a secondary controller, a coolant regulating valve for an alkaline cooler, a flow transmitter at the outlet of the alkaline cooler, and a temperature transmitter at the outlet of the alkaline electrolyzer.

[0026] The temperature transmitter is used to acquire the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer and transmit the actual temperature of the alkaline solution to the main controller.

[0027] The flow transmitter is used to obtain the actual flow rate of alkali at the outlet of the alkali cooler and transmit the actual flow rate of alkali to the secondary controller;

[0028] The coolant regulating valve is used to regulate the coolant flow rate at the coolant inlet of the alkaline cooler;

[0029] The main controller is used to calculate the theoretical flow rate of the alkali solution after cooling based on the actual temperature of the alkali solution transmitted by the temperature transmitter and the set temperature of the alkali solution.

[0030] The secondary controller is used to control the cooling fluid regulating valve of the alkali cooler according to the theoretical flow rate and the actual flow rate of the alkali solution, so as to control the temperature of the alkaline electrolytic cell.

[0031] In some embodiments of this disclosure, the temperature transmitter is located at the alkaline outlet of the alkaline electrolysis cell, the output terminal of the temperature transmitter is connected to the input terminal of the main controller, and the output terminal of the main controller is connected to the sub-controller.

[0032] In some embodiments of this disclosure, the output of the main controller is connected to the input of the secondary controller, the output of the flow transmitter is connected to the input of the secondary controller, the output of the secondary controller is connected to the coolant regulating valve, and the flow transmitter is located at the alkali outlet of the alkali cooler.

[0033] In some embodiments of this disclosure, the coolant regulating valve is located in the coolant inlet pipe of the alkali cooler.

[0034] A third aspect of this disclosure provides a hydrogen production system for an alkaline electrolyzer, including a temperature cascade control device for the alkaline electrolyzer according to any of the above embodiments.

[0035] According to the temperature cascade control method, apparatus, and hydrogen production system of the alkaline electrolyzer according to the embodiments of this disclosure, the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer is first obtained. Based on the actual temperature and the set temperature of the alkaline solution, a fuzzy control algorithm is used to calculate the theoretical flow rate of the alkaline solution input to the alkaline electrolyzer, that is, the theoretical flow rate of the alkaline solution after being cooled by the alkaline solution cooler. Then, the actual flow rate of the alkaline solution at the outlet of the alkaline solution cooler is obtained. Based on the difference between the actual flow rate and the theoretical flow rate of the alkaline solution, the amount of cooling capacity of the alkaline solution that needs to be increased by the alkaline solution cooler is obtained. Without changing the flow rate of the alkaline solution, increasing the flow rate of the coolant in the alkaline solution cooler can increase the cooling capacity of the coolant, thereby transferring the cooling capacity of the coolant to the alkaline solution, achieving the purpose of increasing the cooling capacity of the alkaline solution. The temperature cascade control method for alkaline electrolyzers disclosed herein employs fuzzy computing to process temperature information using rules, thereby improving the ability to handle large time delays and nonlinear problems, enhancing the response speed and adaptability of temperature control in alkaline electrolyzers, making temperature control in alkaline electrolyzers smoother, and achieving rapid and accurate temperature regulation when load conditions change significantly. Attached Figure Description

[0036] Figure 1 A flowchart illustrating the temperature cascade control method for an alkaline electrolyzer according to an embodiment of this disclosure;

[0037] Figure 2 This is a schematic diagram of a temperature cascade control device for an alkaline electrolyzer according to an embodiment of the present disclosure.

[0038] Figure 3 This is a schematic diagram of a hydrogen production system using an alkaline electrolyzer according to an embodiment of this disclosure;

[0039] Figure label:

[0040] 1000. Hydrogen production system using alkaline electrolyte;

[0041] 100. Main controller; 200. Secondary controller; 300. Temperature transmitter; 400. Flow transmitter; 500. Alkali cooler; 501. Coolant regulating valve; 510. Alkali pump; 520. Alkali filter; 600. Alkali electrolyzer; 700. Oxygen separator; 800. Hydrogen separator. Detailed Implementation

[0042] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0043] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0044] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0045] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0046] like Figures 1 to 3 As shown, an embodiment of the first aspect of this disclosure provides a method for cascade temperature control of an alkaline electrolyzer, comprising the following steps:

[0047] S100: Obtain the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer;

[0048] S200: Based on the actual temperature and set temperature of the alkali solution, a fuzzy control algorithm is used to calculate the theoretical flow rate of the alkali solution after it has been cooled by the alkali solution cooler.

[0049] S300: Obtain the actual flow rate of alkali solution at the alkali solution outlet of the alkali solution cooler;

[0050] S400: Controls the coolant flow rate of the alkali cooler based on the actual and theoretical flow rates of the alkali solution.

[0051] According to the temperature cascade control method for an alkaline electrolyzer according to embodiments of this disclosure, the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer is first obtained. Based on the actual temperature and the set temperature of the alkaline solution, a fuzzy control algorithm is used to calculate the theoretical flow rate of the alkaline solution input to the alkaline electrolyzer, i.e., the theoretical flow rate of the alkaline solution after being cooled by the alkaline solution cooler. Then, the actual flow rate of the alkaline solution at the outlet of the alkaline solution cooler is obtained. Based on the difference between the actual flow rate and the theoretical flow rate of the alkaline solution, the required additional cooling capacity of the alkaline solution cooler is obtained. Without changing the flow rate of the alkaline solution, increasing the flow rate of the coolant in the alkaline solution cooler can increase the cooling capacity of the coolant, thereby transferring the cooling capacity of the coolant to the alkaline solution, achieving the purpose of increasing the cooling capacity of the alkaline solution. The temperature cascade control method for an alkaline electrolyzer of this disclosure, by employing fuzzy calculation and using rules to process temperature information, improves the ability to handle large lag and nonlinear problems, improves the response speed and adaptability of temperature control in the alkaline electrolyzer, makes the temperature control of the alkaline electrolyzer smoother, and achieves fast and accurate temperature adjustment when the load conditions change significantly.

[0052] S200: The step of calculating the theoretical flow rate of the alkali solution after being cooled by the alkali solution cooler using a fuzzy control algorithm based on the actual temperature and set temperature of the alkali solution includes:

[0053] S210: Calculate the difference (e) between the actual temperature of the alkali solution and the set temperature of the alkali solution, and the error change rate (Δe);

[0054] S220: Based on fuzzy rules, the difference (e) and the rate of change of error (Δe) are transformed into a fuzzy set of temperature regulation variables;

[0055] S230: Convert the fuzzy set of temperature regulation variables into a definite theoretical flow rate of alkali solution.

[0056] Specifically, firstly, based on the actual temperature and set temperature of the alkali solution, the difference e and error rate Δe are calculated. Then, according to fuzzy rules, the difference e and error rate Δe are transformed into a fuzzy set of temperature control variables. Finally, the fuzzy set of temperature control variables is transformed into the theoretical flow rate of the alkali solution, thereby obtaining the theoretical flow rate of the alkali solution through a fuzzy control algorithm. The main controller, through the above fuzzy control algorithm, can achieve more precise control in nonlinear environments.

[0057] Specifically, the fuzzy rules include:

[0058] IF e is NB ANDΔe isΔNB THEN u is uPB;

[0059] IF e is NS ANDΔe isΔZ THEN u is uPS;

[0060] IF e is Z ANDΔe isΔZ THEN u is uZ;

[0061] IF e is PS ANDΔe isΔZ THEN u is uNS;

[0062] IF e is PB ANDΔe isΔPB THEN u is uNB;

[0063] Where e is the difference between the actual temperature of the alkali solution and the set temperature of the alkali solution; NB represents a very low temperature deviation with a large negative deviation, NS represents a relatively low temperature deviation with a small negative deviation, and the temperature deviation of NB is less than that of NS; Z represents a zero temperature deviation; PS represents a relatively high temperature deviation with a small positive deviation, PB represents a very high temperature deviation with a large positive deviation, and the temperature deviation of PS is greater than that of NS and less than that of PB; Δe is the rate of change of deviation; ΔNB represents a rapidly decreasing temperature deviation with a large negative rate of change of deviation, ΔNS represents a slowly decreasing temperature deviation with a small negative rate of change of deviation, and the rate of decrease of the temperature deviation of ΔNB is greater than that of ΔNS. The rate of decrease in temperature deviation; ΔZ represents a constant temperature deviation; ΔPS represents a small positive rate of change in deviation, indicating a slow decrease in temperature deviation; ΔPB represents a large positive rate of change in deviation, indicating a rapid increase in temperature deviation, with the rate of increase in temperature difference of ΔPB being greater than that of ΔPS; u represents the flow rate regulation variable; uNB represents a large negative flow rate variable, indicating a significant reduction in flow rate; uNS represents a small negative flow rate variable, indicating a slight reduction in flow rate, with the reduction in flow rate of uNB being greater than that of uNS; uZ represents a constant flow rate; uPS represents a small positive flow rate variable, indicating a slight increase in flow rate; uPB represents a large positive flow rate variable, indicating a significant increase in flow rate, with the increase in flow rate of uPS being greater than that of uPS.

[0064] S400: The steps for controlling the coolant flow rate of the alkali cooler based on the actual and theoretical flow rates of the alkali solution include:

[0065] Based on the actual and theoretical flow rates of the alkali solution, a PID method is used to control the coolant flow rate of the alkali solution cooler.

[0066] The secondary controller uses an adaptive PID method to automatically adjust the PID parameters according to the current operating status to regulate the coolant flow rate of the alkali cooler, thereby improving the system's response speed and stability.

[0067] In some embodiments of this disclosure, the step of controlling the coolant flow rate of the alkali cooler using a PID method based on the actual flow rate and the theoretical flow rate of the alkali solution includes:

[0068] If the difference between the actual flow rate and the theoretical flow rate of the alkali solution is greater than the preset difference, the proportional gain Kp is increased.

[0069] If the difference between the actual flow rate and the theoretical flow rate of the alkali solution is less than the preset difference, the proportional-integral gain Ki is increased.

[0070] When the difference between the actual flow rate and the theoretical flow rate of the alkali solution is greater than the preset difference, the proportional gain Kp is increased to speed up the response; when the difference between the actual flow rate and the theoretical flow rate of the alkali solution is less than the preset difference, the integral gain Ki is increased to eliminate steady-state error.

[0071] An embodiment of the second aspect of this disclosure provides a temperature cascade control device for an alkaline electrolyzer, including a main controller 100, a secondary controller 200, a coolant regulating valve 501 for an alkaline cooler 500, a flow transmitter 400 at the outlet of the alkaline cooler 500, and a temperature transmitter 300 at the outlet of the alkaline electrolyzer 600.

[0072] Temperature transmitter 300 is used to acquire the actual temperature of the alkaline solution at the outlet of alkaline electrolysis cell 600 and transmit the actual temperature of the alkaline solution to main controller 100.

[0073] The flow transmitter 400 is used to obtain the actual flow rate of the alkali solution at the outlet of the alkali solution cooler 500 and transmit the actual flow rate of the alkali solution to the secondary controller 200.

[0074] The coolant regulating valve 501 is used to regulate the coolant flow rate at the coolant inlet of the alkali cooler 500;

[0075] The main controller 100 is used to calculate the theoretical flow rate of the alkali solution after it has been cooled, based on the actual temperature of the alkali solution transmitted by the temperature transmitter 300 and the set temperature of the alkali solution.

[0076] The secondary controller 200 is used to control the cooling liquid regulating valve 501 of the alkali cooler 500 according to the theoretical flow rate and the actual flow rate of the alkali solution, so as to control the temperature of the alkaline electrolytic cell 600.

[0077] According to the temperature cascade control device for the alkaline electrolyzer according to an embodiment of this disclosure, the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer 600 is first obtained by the temperature transmitter 300 and transmitted to the main controller 100. The main controller 100 calculates the theoretical flow rate of the alkaline solution input to the alkaline electrolyzer, i.e., the theoretical flow rate of the alkaline solution after being cooled by the alkaline solution cooler 500, based on the actual temperature and the set temperature of the alkaline solution using a fuzzy control algorithm. Then, the flow transmitter 400 obtains the actual flow rate of the alkaline solution at the outlet of the alkaline solution cooler 500 and transmits it to the secondary controller 200. The secondary controller 200 obtains the amount of cooling capacity of the alkaline solution that needs to be added to the alkaline solution cooler 500 based on the difference between the actual flow rate and the theoretical flow rate of the alkaline solution. By increasing the flow rate of the cooling liquid in the alkaline solution cooler 500 without changing the flow rate of the alkaline solution, the cooling capacity of the cooling liquid can be increased, thereby transferring the cooling capacity of the cooling liquid to the alkaline solution and achieving the purpose of increasing the cooling capacity of the alkaline solution. The temperature cascade control device for the alkaline electrolyzer disclosed herein uses a fuzzy calculation method by the main controller 100 to process temperature information and transmit it to the secondary controller 200. The secondary controller 200 regulates the flow rate of the coolant in the alkaline cooler 500 to regulate the temperature of the alkaline electrolyzer 600. This improves the ability to handle large lag and nonlinear problems, enhances the response speed and adaptability of the temperature control of the alkaline electrolyzer 600, makes the temperature control of the alkaline electrolyzer 600 smoother, and achieves rapid and accurate temperature regulation when the load conditions change significantly.

[0078] In some embodiments of this disclosure, a temperature transmitter 300 is located at the alkaline outlet of the alkaline electrolysis cell. The output of the temperature transmitter is connected to the input of the main controller 100 to transmit the temperature information of the alkaline outlet of the alkaline electrolysis cell 600 to the main controller 100. The output of the main controller 100 is connected to the secondary controller 200 to transmit the theoretical flow rate of the alkaline obtained by the main controller 100 through a fuzzy algorithm to the secondary controller 200.

[0079] In some embodiments of this disclosure, the output of the main controller 100 is connected to the input of the secondary controller 200 to transmit the theoretical flow rate of the alkali solution obtained by the main controller 100 through a fuzzy algorithm to the secondary controller 200. The output of the flow transmitter 400 is connected to the input of the secondary controller 200. The flow transmitter 400 is located at the alkali solution outlet of the alkali solution cooler 500 to transmit the actual flow rate of the alkali solution output by the flow transmitter 400 to the secondary controller. The output of the secondary controller 200 is connected to the coolant regulating valve 501 so that the secondary controller 200 can control the opening degree of the coolant regulating valve 501 according to the difference between the actual flow rate of the alkali solution and the theoretical flow rate of the alkali solution.

[0080] In some embodiments of this disclosure, a coolant regulating valve 501 is provided in the coolant inlet pipe of the alkali cooler 500, so as to control the cooling capacity of the alkali output from the alkali cooler 500 by adjusting the coolant regulating valve 501, thereby controlling the temperature of the alkaline electrolytic cell 600.

[0081] like Figure 3 As shown, the third aspect of this disclosure provides a hydrogen production system 1000 for an alkaline electrolyzer, including a temperature cascade control device for the alkaline electrolyzer according to any of the above embodiments.

[0082] Specifically, the hydrogen production system for the electrolyzer also includes an alkali pump 510, an alkali filter 520, an alkaline electrolyzer 600, an oxygen separator 700, and a hydrogen separator 800. The oxygen-side outlet of the alkaline electrolyzer 600 is connected to the oxygen separator 700. A temperature transmitter 300 is installed on the pipeline connecting the oxygen-side outlet of the alkaline electrolyzer 600 and the oxygen separator 700. The hydrogen-side outlet of the alkaline electrolyzer 600 is connected to the hydrogen separator 800. The oxygen separator 700... The outlet of 0 merges with the outlet of hydrogen separator 800 and is connected to alkaline cooler 500 via alkaline pump 510. The coolant inlet of alkaline cooler 500 is equipped with coolant regulating valve 501. The outlet of alkaline cooler 500 is connected to the inlet of alkaline filter 520. The outlet of alkaline filter 520 is connected to the alkaline inlet of alkaline electrolysis cell 600. Flow transmitter 400 is installed at the alkaline outlet of alkaline cooler 500 or at the outlet of alkaline filter 520.

[0083] The hydrogen production system of the alkaline electrolyzer in this embodiment has the same technical effect as the temperature cascade control device of the alkaline electrolyzer, and will not be described again here.

[0084] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the atoms of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for cascade temperature control of an alkaline electrolyzer, characterized in that, Includes the following steps: Obtain the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer; Based on the actual temperature and set temperature of the alkali solution, a fuzzy control algorithm is used to calculate the theoretical flow rate of the alkali solution after being cooled by the alkali solution cooler. Obtain the actual flow rate of alkali solution at the alkali solution outlet of the alkali solution cooler; The flow rate of the coolant in the alkali cooler is controlled based on the actual flow rate and the theoretical flow rate of the alkali solution.

2. The temperature cascade control method for an alkaline electrolyzer according to claim 1, characterized in that, The step of calculating the theoretical flow rate of the alkali solution after cooling by the alkali solution cooler using a fuzzy control algorithm based on the actual temperature and set temperature of the alkali solution includes: Calculate the difference (e) between the actual temperature of the alkali solution and the set temperature of the alkali solution, and the error change rate (Δe); The difference (e) and the rate of change of error (Δe) are transformed into a fuzzy set of temperature regulation variables according to the fuzzy rules. The fuzzy set of temperature regulation variables is converted into a definite theoretical flow rate of alkali solution.

3. The temperature cascade control method for an alkaline electrolyzer according to claim 2, characterized in that, The fuzzy rules include: IF eis NB ANDΔeisΔNB THEN uis uPB; IF eis NS ANDΔeisΔZ THEN uis uPS; IF eis Z ANDΔeisΔZ THEN uis uZ; IF eis PS ANDΔeisΔZ THEN uis uNS; IF eis PB ANDΔeisΔPB THEN uis uNB; Where e is the difference between the actual temperature of the alkali solution and the set temperature of the alkali solution; NB is a large negative deviation, NS is a small negative deviation, and the temperature deviation of NB is less than that of NS; Z is a zero temperature deviation; PS is a small positive deviation, PB is a large positive deviation, and the temperature deviation of PS is greater than that of NS and less than that of PB; Δe is the rate of change of deviation; ΔNB is a large negative rate of change of deviation, ΔNS is a small negative rate of change of deviation, and the rate of decrease of the temperature deviation of ΔNB is greater than that of ΔNS; ΔZ is a constant temperature deviation; ΔPS is a small positive rate of change of deviation, ΔPB is a large positive rate of change of deviation, and the rate of increase of the temperature difference of ΔPB is greater than that of ΔPS; u is the flow rate regulation variable; uNB is a large negative flow rate variable, uNS is a small negative flow rate variable, and the decrease in flow rate of uNB is greater than that of uNS; uZ is a constant flow rate; uPS is a small positive flow rate variable, uPB is a large positive flow rate variable, and the increase in flow rate of uPS is greater than that of uPS.

4. The temperature cascade control method for an alkaline electrolyzer according to claim 1, characterized in that, The steps for controlling the coolant flow rate of the alkali cooler based on the actual and theoretical flow rates of the alkali solution include: Based on the actual and theoretical flow rates of the alkali solution, a PID method is used to control the coolant flow rate of the alkali solution cooler.

5. The temperature cascade control method for an alkaline electrolyzer according to claim 4, characterized in that, The method of controlling the coolant flow rate of the alkali cooler using the PID method based on the actual and theoretical flow rates of the alkali solution includes: If the difference between the actual flow rate and the theoretical flow rate of the alkali solution is greater than the preset difference, the proportional gain Kp is increased. If the difference between the actual flow rate and the theoretical flow rate of the alkali solution is less than the preset difference, the proportional-integral gain Ki is increased.

6. A temperature cascade control device for an alkaline electrolytic cell, characterized in that, Includes a main controller, a secondary controller, a coolant regulating valve for the alkali cooler, a flow transmitter at the outlet of the alkali cooler, and a temperature transmitter at the outlet of the alkaline electrolysis cell; The temperature transmitter is used to acquire the actual temperature of the alkaline solution at the outlet of the alkaline electrolyzer and transmit the actual temperature of the alkaline solution to the main controller. The flow transmitter is used to obtain the actual flow rate of alkali at the outlet of the alkali cooler and transmit the actual flow rate of alkali to the secondary controller; The coolant regulating valve is used to regulate the coolant flow rate at the coolant inlet of the alkaline cooler; The main controller is used to calculate the theoretical flow rate of the alkali solution after cooling based on the actual temperature of the alkali solution transmitted by the temperature transmitter and the set temperature of the alkali solution. The secondary controller is used to control the cooling fluid regulating valve of the alkali cooler according to the theoretical flow rate and the actual flow rate of the alkali solution, so as to control the temperature of the alkaline electrolytic cell.

7. The temperature cascade control device for an alkaline electrolytic cell according to claim 6, characterized in that, The temperature transmitter is located at the alkaline outlet of the alkaline electrolysis cell. The output terminal of the temperature transmitter is connected to the input terminal of the main controller, and the output terminal of the main controller is connected to the auxiliary controller.

8. The temperature cascade control device for an alkaline electrolytic cell according to claim 6, characterized in that, The output of the main controller is connected to the input of the secondary controller, the output of the flow transmitter is connected to the input of the secondary controller, the output of the secondary controller is connected to the coolant regulating valve, and the flow transmitter is located at the alkali outlet of the alkali cooler.

9. The temperature cascade control device for an alkaline electrolytic cell according to claim 6, characterized in that, The coolant regulating valve is located on the coolant inlet pipe of the alkali cooler.

10. A hydrogen production system using an alkaline electrolyzer, characterized in that, The device includes the temperature cascade control device for the alkaline electrolyzer as described in any one of claims 6-9.

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