CN116288517A - Alkaline electrolysis system and alkali liquor mixing proportion control method thereof - Google Patents

Alkaline electrolysis system and alkali liquor mixing proportion control method thereof Download PDF

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Publication number
CN116288517A
CN116288517A CN202310133427.8A CN202310133427A CN116288517A CN 116288517 A CN116288517 A CN 116288517A CN 202310133427 A CN202310133427 A CN 202310133427A CN 116288517 A CN116288517 A CN 116288517A
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China
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alkali liquor
cathode
anode
hydrogen
oxygen
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Inventor
史翊翔
张蔚喆
刘梦华
刘厚权
李爽
郝培璇
王海光
蔡宁生
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Beijing Huayi Hydrogen Technology Co ltd
Tsinghua University
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Beijing Huayi Hydrogen Technology Co ltd
Tsinghua University
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Priority to CN202310133427.8A priority Critical patent/CN116288517A/en
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/50—Processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Abstract

The present disclosure relates to an alkaline electrolysis system and a control method of alkali liquor mixing ratio thereof. The control method comprises mixing part of the anode alkali liquor and part of the cathode alkali liquor, and adjusting the mixing proportion to obtain mixed alkali liquor; equally distributing the mixed alkali liquor and respectively inputting the mixed alkali liquor into the cathode side and the anode side of the alkaline electrolysis stack; wherein, based on the purity of oxygen in the anode gas, the proportion of the cathode alkali liquor in the mixed alkali liquor is adjusted, and based on the purity of hydrogen in the cathode gas, the proportion of the anode alkali liquor in the mixed alkali liquor is adjusted. The mixing proportion of the alkaline solution in the cathode and anode loops can be dynamically adjusted so as to synchronously meet the requirements of the running performance and the safety characteristic of the system according to the actual working conditions. In the aspect of the system, a multi-precision coupling alkali liquor mixing proportion control module is adopted, and the alkali liquor mixing proportion of the cathode and anode loops is dynamically adjusted by selecting proper precision, so that the common promotion of adjusting speed, stability and accuracy is realized.

Description

Alkaline electrolysis system and alkali liquor mixing proportion control method thereof
Technical Field
The present disclosure relates to the field of hydrogen production by alkaline electrolysis of water, and more particularly, to an alkaline electrolysis system and a control method for alkali liquor mixing ratio thereof.
Background
The renewable energy sources such as wind power, photovoltaic, water power and the like are used as power sources for water electrolysis hydrogen production, so that the efficient preparation of green hydrogen and the dynamic absorption of renewable energy sources can be synchronously realized, and the development of renewable energy sources and the transformation of energy structures can be effectively promoted.
In various water electrolysis hydrogen production technologies, the running life of alkaline water electrolysis is longer, the construction cost is lower, the technology is the most mature, and the large-scale commercialization process is completed, but the higher electrolysis voltage leads to high unit hydrogen production energy consumption, and the electrolysis performance needs to be further improved to reduce the electricity cost. Meanwhile, the mutual blending of hydrogen and oxygen in the alkaline electrolysis system reduces the purity of the product gas, provides challenges for the safety characteristics of the system, can cause the generation of explosive mixtures and limits the coordinated operation of the alkaline electrolysis system and the fluctuation renewable energy source.
In the existing alkaline electrolysis systems, the cathode and anode lye is mostly adopted to be completely circulated independently or completely mixed, and a worker is usually required to manually adjust the opening of a single valve to realize the flow dynamic control. When completely independent circulation is adopted, gas mixing caused by mixing of alkaline solution of anode and cathode can be avoided, but during long-term operation, OH-is generated at the cathode and at the anode due to electrode reactionGenerates obvious alkali solution concentration gradient in the electrolytic tank, causes the lack of reactants at the anode and the reduction of alkali solution conductivity, increases the mass transfer overpotential eta under the same current density mass Ohmic overpotential eta ohm The electrolysis performance is obviously reduced; when the complete mixing circulation is adopted, the concentration gradient of the alkaline solution of the anode and the cathode can be balanced to improve the electrolysis performance, but the mixing of the alkaline solution of the anode and the cathode aggravates the gas mixing, improves the content of outlet gas HTO (hydrogen in oxygen) and OTH (oxygen in hydrogen), weakens the safety characteristic of the system operation, and is more remarkable when the renewable energy sources with the fluctuation of wind power, photovoltaic, water power and the like are used as the electric power sources. The control method for dynamically adjusting the mixing ratio of the cathode and anode alkali solutions based on the real-time values of HTO and OTH is lacking, and the requirements of the system on the running performance and the safety characteristic are difficult to synchronously meet according to the actual working conditions. Meanwhile, when a single valve is adopted for alkali liquor flow regulation, if the valve regulation precision is obviously smaller than the regulation requirement, the valve opening is required to be changed to a large extent, the required regulation time is longer, oscillation is easy to occur, and the regulation speed and stability are poor; if the valve adjusting precision is obviously greater than the adjusting requirement, the opening change of the valve with smaller degree can cause larger fluctuation of alkali liquor flow, and the adjusting accuracy is poor.
Disclosure of Invention
In order to solve the defects in the prior art, the present disclosure provides an alkaline electrolysis system and a control method for the alkali liquor mixing ratio thereof.
The technical solution of the first aspect of the present disclosure provides a method for controlling a mixing ratio of alkaline solution in an alkaline electrolysis system, the method comprising:
carrying out gas-liquid separation on the mixture from the cathode outlet of the alkaline electrolytic stack to obtain cathode alkali liquor and cathode gas;
carrying out gas-liquid separation on the mixture from the anode outlet of the alkaline electrolytic stack to obtain anode alkali liquor and anode gas;
mixing a part of the anode alkali liquor with a part of the cathode alkali liquor, and adjusting the mixing proportion to obtain mixed alkali liquor;
equally distributing the mixed alkali liquor and respectively inputting the mixed alkali liquor into the cathode side and the anode side of the alkaline electrolysis stack;
wherein, adjusting the mixing ratio comprises:
adjusting the proportion of the cathode lye in the mixed lye based on the purity of the oxygen in the anode gas, and
the ratio of the anode lye in the mixed lye is adjusted based on the purity of the hydrogen in the cathode gas.
According to the alkali liquor mixing proportion control method of the alkaline electrolysis system, provided by the scheme, based on the measurement results of the oxygen and hydrogen purity analysis module and the specific deviation of the real-time values and the set values of HTO (hydrogen in oxygen) and OTH (oxygen in hydrogen), the alkali liquor mixing proportion of the cathode and anode loops is selected to be dynamically adjusted with proper precision, so that the requirements of the system on the running performance and the safety characteristic are synchronously met according to the actual working conditions, and the common promotion of the adjustment speed, the stability and the accuracy is realized.
The more specific technical scheme comprises the following steps:
preferably, the main component of the cathode gas is hydrogen and mixed with oxygen impurities, and the main component of the anode gas is oxygen and mixed with hydrogen impurities;
the adjusting of the mixing ratio comprises:
the amount of oxygen in hydrogen in the cathode gas and the amount of hydrogen in oxygen in the anode gas are continuously measured.
Preferably, adjusting the proportion of the cathodic lye in the mixed lye comprises:
setting a preset range of hydrogen in oxygen and a multi-level deviation threshold value of hydrogen in oxygen;
when the hydrogen value in oxygen exceeds the preset range of hydrogen in oxygen, obtaining a hydrogen deviation value in oxygen;
and according to the grade which is met by the hydrogen deviation value in oxygen in the hydrogen deviation threshold value in oxygen, adjusting the proportion of the cathode alkali liquor in the mixed alkali liquor according to the grade.
Preferably, the electrolysis system is controlled to shut down when the hydrogen-in-oxygen bias value exceeds a maximum level in the hydrogen-in-oxygen bias threshold.
Preferably, adjusting the ratio of the anode lye in the mixed lye comprises:
setting a preset hydrogen-in-oxygen range and a multi-level hydrogen-in-oxygen deviation threshold;
when the oxygen value in the hydrogen exceeds the preset range of oxygen in the hydrogen, obtaining an oxygen deviation value in the hydrogen;
and according to the grade which is met by the oxygen deviation value in hydrogen in the oxygen deviation threshold value in hydrogen, adjusting the proportion of the anode alkali liquor in the mixed alkali liquor according to the grade.
Preferably, the electrolysis system is controlled to shut down when the hydrogen oxygen bias value exceeds a maximum level in the hydrogen oxygen bias threshold.
Preferably, the part of the cathode alkali liquor which does not participate in mixing and the equally distributed mixed alkali liquor are jointly input to the cathode side;
and (3) inputting the part which does not participate in mixing in the anode alkali liquor and the equally distributed mixed alkali liquor to the anode side.
The technical solution of the second aspect of the present disclosure provides an alkaline electrolysis system, which includes:
an alkaline electrolytic stack;
the cathode loop comprises a cathode outlet of the alkaline electrolytic stack, a main gas-liquid separator of the cathode loop, an alkali liquor circulating pump of the cathode loop and a cathode side of the alkaline electrolytic stack which are connected in sequence;
the anode loop comprises an anode outlet of the alkaline electrolytic stack, an anode loop main gas-liquid separator, an anode loop alkali liquor circulating pump and an anode side of the alkaline electrolytic stack which are connected in sequence;
the hydrogen purity analysis module is capable of measuring the hydrogen purity of the gas from the cathode loop main gas-liquid separator;
an oxygen purity analysis module capable of measuring the oxygen purity of the gas from the anode loop main gas-liquid separator;
the alkali liquor mixing proportion control module is connected with the cathode loop, the anode loop and the cathode side and the anode side of the alkaline electrolytic stack, and can respectively acquire and mix part of alkali liquor in the cathode loop and part of alkali liquor in the anode loop, and the mixed alkali liquor is equally input into the cathode side and the cathode side;
the alkali liquor mixing proportion control module is configured to receive control signals from the hydrogen purity analysis module and/or the oxygen purity analysis module and control the alkali liquor mixing proportion according to the control signals.
Preferably, the hydrogen purity analysis module is configured to generate a control signal comprising the oxygen value in hydrogen;
the oxygen purity analysis module is configured to generate a control signal comprising a hydrogen quantity in oxygen.
Preferably, the alkali liquor mixing proportion control module comprises:
a mixing circuit connected to the cathode side and the anode side, capable of mixing and equally delivering the alkali solution inputted thereto;
the input end of the cathode loop alkali liquor mixing proportion control module is connected with the cathode loop, the output end of the cathode loop alkali liquor mixing proportion control module is connected with the mixing loop, and the flow rate of alkali liquor output to the mixing loop can be regulated based on a control signal from the oxygen purity analysis module;
and the input end of the anode loop alkali liquor mixing proportion control module is connected with the anode loop, the output end of the anode loop alkali liquor mixing proportion control module is connected with the mixing loop, and the alkali liquor flow output to the mixing loop can be regulated based on a control signal from the hydrogen purity analysis module.
Preferably, the cathode loop alkali liquor mixing proportion control module and/or the anode loop alkali liquor mixing proportion control module comprises a plurality of stages of parallel regulating valve sub-loops with different precision, and the opening degree of one stage of regulating valve can be increased or decreased based on a control signal.
Preferably, the method further comprises: a water replenishing storage module and a water replenishing pump; the water replenishing pump can be used for extracting pure water in the water replenishing storage module and inputting the pure water into the cathode loop main gas-liquid separator under pressure when in operation.
Preferably, the method further comprises:
the cathode loop auxiliary gas-liquid separator is connected with the hydrogen purity analysis module and the cathode loop main gas-liquid separator;
the anode loop auxiliary gas-liquid separator is connected with the oxygen purity analysis module and the anode loop main gas-liquid separator.
Preferably, the method further comprises: a direct current power supply connected to the cathode side and the anode side of the alkaline electrolyte stack, respectively;
the direct current power supply is connected with a rectifier, and the rectifier is connected with a fluctuation renewable energy source.
The control method and the control system provided in the technical scheme aim to dynamically adjust the mixing proportion of alkaline solution in the cathode and anode loops based on the specific deviation between the real-time values of HTO and OTH and the set values according to the measurement results of the oxygen and hydrogen purity analysis modules so as to synchronously meet the requirements of the system on the operation performance and the safety characteristics according to the actual working conditions.
In the aspect of adjusting the mixing proportion, the technical scheme disclosed by the invention emphasizes on adopting a multi-precision coupling alkali liquor mixing proportion control module, and selects proper precision to dynamically adjust the mixing proportion of the cathode and anode loop alkali liquor so as to realize the common promotion of adjusting speed, stability and accuracy.
Drawings
The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.
FIG. 1 shows a schematic view of an alkaline electrolysis system provided in an embodiment of the present application;
FIG. 2 is an example of a method for dynamically adjusting the mixing ratio of alkaline solution in a cathode loop in an embodiment of the present application;
FIG. 3 is an example of a method for dynamically adjusting the mixing ratio of alkaline solution in an anode loop in an embodiment of the present application;
reference numerals in the drawings denote:
1. renewable energy sources; 2. a rectifier; 3. a direct current power supply; 4. an alkaline electrolytic stack;
5. a cathode loop main gas-liquid separator; 6. an anode loop main gas-liquid separator; 7. a cathode loop auxiliary gas-liquid separator; 8. an anode loop auxiliary gas-liquid separator;
9. a hydrogen purity analysis module; 10. an oxygen purity analysis module;
11. a cathode loop alkali liquor circulating pump; 12. an anode loop alkali liquor circulating pump;
13. a water replenishing storage module; 14. a water supplementing pump;
15. a cathode loop alkali liquor mixing proportion control module; 16. and the anode loop alkali liquor mixing proportion control module.
Detailed Description
The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This application may, however, be embodied in many different forms and should not be construed as 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. Like numbers refer to like elements throughout.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, "a," "an," "the," and "at least one" are not meant to limit the amount, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, the meaning of "a component" is the same as "at least one component". The "at least one" should not be construed as limited to the number "one". "or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.
Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms as defined in commonly used dictionaries should be interpreted as having the same meaning as that of the relevant art context and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "comprising" or "including" indicates a property, quantity, step, operation, component, element, or combination thereof, but does not preclude other properties, quantities, steps, operations, components, elements, or combinations thereof.
In the prior art, lye circulation loops in alkaline electrolysis systemsMost of the main control methods adopt completely independent circulation or completely mixed circulation of the alkaline solution of the cathode and the anode. The applicant has realized in research that when completely independent circulation is adopted, gas mixing caused by mixing of alkaline solution of anode and cathode can be avoided, but when the device is operated for a long time, OH is reacted by electrodes - The generation at the cathode and the consumption at the anode generate obvious alkali solution concentration gradient in the electrolytic tank, which leads to the loss of reactants at the anode and the reduction of alkali solution conductivity, and increases the mass transfer overpotential eta under the same current density mass Ohmic overpotential eta ohm The electrolysis performance is obviously reduced; when the complete mixing circulation is adopted, although the concentration gradient of the cathode and anode alkali liquor can be balanced to improve the electrolysis performance, the mixing of the cathode and anode alkali liquor aggravates the gas mixing, the contents of hydrogen HTO (Hydrogen to Oxygen) in oxygen and oxygen OTH (Oxygen to Hydrogen) in hydrogen in outlet gas are improved, the safety characteristic of system operation is weakened (the low explosion limit of the hydrogen is 4%), and the system is more remarkable when the fluctuation renewable energy sources such as wind power, photovoltaic, hydropower and the like are used as electric power sources.
In view of the above, the technical idea of the present disclosure aims to provide a brand-new cathode-anode alkali solution mixing idea on the basis of overcoming the advantages and disadvantages of the above-mentioned "complete independent circulation" and "complete mixing circulation".
In addition, in the prior art, for the flow adjustment of the alkali liquor in the circulation loop, a worker is required to manually adjust the opening of a single valve to realize dynamic flow control, that is, the prior art lacks a control method for dynamically adjusting the mixing ratio of the cathode and anode alkali liquor based on real-time values of HTO and OTH, and is difficult to synchronously meet the requirements of the running performance and the safety characteristic of the system according to the actual working condition; meanwhile, the applicant further discovers that when a single valve is adopted for alkali liquor flow regulation, if the valve regulation precision is obviously smaller than the regulation requirement, the valve opening is required to be changed to a greater extent, the required regulation time is longer, oscillation is easy to occur, and the regulation speed and stability are poor; if the valve adjusting precision is obviously greater than the adjusting requirement, the opening change of the valve with smaller degree can cause larger fluctuation of alkali liquor flow, and the adjusting accuracy is poor.
In this regard, the technical idea of the present disclosure further includes that a plurality of stages of parallel regulating valves (and sub-circuits thereof) having different accuracies are provided in the proportional control module, and a proper accuracy is selected to dynamically regulate the mixing ratio of the alkaline solutions of the cathode and anode circuits, so as to achieve a common improvement in regulating speed, stability and accuracy.
Hereinafter, exemplary embodiments according to the present application will be described with reference to the accompanying drawings.
An embodiment of a method for controlling the mixing ratio of alkaline solution in an alkaline electrolysis system is provided as follows, which mainly comprises the following steps:
carrying out gas-liquid separation on the mixture from the cathode outlet of the alkaline electrolytic stack to obtain cathode alkali liquor and cathode gas; carrying out gas-liquid separation on the mixture from the anode outlet of the alkaline electrolytic stack to obtain anode alkali liquor and anode gas; the mixture is mainly the alkali liquor to be recycled which is electrolyzed and mixed with gas generated by electrolysis. The cathode gas is mainly hydrogen and a small amount of oxygen, and the anode gas is mainly oxygen and a small amount of hydrogen.
Mixing a part of the anode alkali liquor with a part of the cathode alkali liquor, and adjusting the mixing proportion to obtain mixed alkali liquor; part of the anode lye and cathode lye which do not participate in the mixing process are directly circulated into the anode or cathode side of the electrolytic stack.
Equally distributing the mixed alkali liquor and respectively inputting the mixed alkali liquor into the cathode side and the anode side of the alkaline electrolysis stack;
wherein, adjusting the mixing ratio comprises:
adjusting the proportion of the cathode lye in the mixed lye based on the purity of the oxygen in the anode gas, and
the ratio of the anode lye in the mixed lye is adjusted based on the purity of the hydrogen in the cathode gas.
In accordance with an embodiment of the present disclosure, in a preferred embodiment, it is desirable to continuously measure the hydrogen-in-oxygen value in the anode gas and the oxygen-in-hydrogen value in the cathode gas to achieve dynamic adjustment based on the HTO and OTH real-time values.
In accordance with an embodiment of the present disclosure, in a preferred embodiment, as shown in fig. 2, 3:
setting a preset range of hydrogen in oxygen and a multi-level deviation threshold value of hydrogen in oxygen;
when the hydrogen value in oxygen exceeds the preset range of hydrogen in oxygen, obtaining a hydrogen deviation value in oxygen;
and according to the grade which is met by the hydrogen deviation value in oxygen in the hydrogen deviation threshold value in oxygen, adjusting the proportion of the cathode alkali liquor in the mixed alkali liquor according to the grade.
Setting a preset hydrogen-in-oxygen range and a multi-level hydrogen-in-oxygen deviation threshold;
when the oxygen value in the hydrogen exceeds the preset range of oxygen in the hydrogen, obtaining an oxygen deviation value in the hydrogen;
and according to the grade which is met by the oxygen deviation value in hydrogen in the oxygen deviation threshold value in hydrogen, adjusting the proportion of the anode alkali liquor in the mixed alkali liquor according to the grade.
Exemplary, setting the upper hydrogen in oxygen limit HTO max Lower limit HTO min Hydrogen bias threshold delta in multi-stage oxygen HTO,i (i=0, 1, …, n) and the real-time outlet gas HTO measured by the oxygen purity analysis module are control signals. When the HTO exceeds the set range, the HTO can be based on HTO and HTO max And HTO min According to the flow scheme shown in FIG. 2, the flow of the cathode lye into the mixture is changed.
Illustratively, the upper limit OTH of oxygen in hydrogen is set max Lower limit OTH min Oxygen bias threshold delta in multi-stage hydrogen OTH,i (i=0, 1, …, n) and the real-time outlet gas OTH measured by the hydrogen purity analysis module are control signals. When the OTH exceeds the set range, the OTH can be based on the OTH and the OTH max And OTH min According to the flow scheme shown in fig. 3, the flow of the anode lye into the mix is changed.
In accordance with an embodiment of the present disclosure, in a preferred embodiment, the electrolysis system is controlled to shut down when the hydrogen to oxygen deviation value exceeds a maximum level in the hydrogen to oxygen deviation threshold. Alternatively, controlling the electrolysis system to shut down when the hydrogen-in-oxygen bias value exceeds a maximum level in the hydrogen-in-oxygen bias threshold
According to the implementation mode of the disclosure, in a preferred embodiment, the part of the cathode alkali liquor which does not participate in mixing is input to the cathode side together with the equally distributed mixed alkali liquor; and (3) inputting the part which does not participate in mixing in the anode alkali liquor and the equally distributed mixed alkali liquor to the anode side.
An example of an alkaline electrolysis system is provided below.
As shown in fig. 1, after the renewable energy source 1 with fluctuation such as wind power, photovoltaic, water power and the like is rectified by the rectifier 2, an electric power source is provided for the alkaline electrolysis stack 4 in the form of a direct current power supply 3 to drive the water electrolysis reaction to be carried out:
H 2 O→H 2 +0.5O 2
the alkaline electrolysis stack cathode outlet alkali liquor sequentially passes through a cathode loop main gas-liquid separator 5 and an auxiliary gas-liquid separator 7, gas components enter a hydrogen purity analysis module 9 (mainly hydrogen and a small amount of oxygen), alkali liquor components enter a subsequent circulation loop after being pressurized by a cathode loop alkali liquor circulation pump 11, part of cathode alkali liquor passes through a cathode loop alkali liquor mixing proportion control module 15, is mixed with anode alkali liquor passing through an anode loop alkali liquor mixing proportion control module 16 in the mixing loop, and enters the cathode loop again after being evenly distributed, and enters the cathode side of the alkaline electrolysis stack 4 together with part of cathode alkali liquor which does not participate in the mixing process;
the alkaline electrolysis stack anode outlet alkali liquor sequentially passes through an anode loop main gas-liquid separator 6 and an auxiliary gas-liquid separator 8, gas components enter an oxygen purity analysis module 10 (mainly oxygen and a small amount of hydrogen), alkali liquor components enter a subsequent circulation loop after being pressurized by an anode loop alkali liquor circulation pump 12, part of the anode alkali liquor passes through an anode loop alkali liquor mixing proportion control module 16, is mixed with cathode alkali liquor passing through a cathode loop alkali liquor mixing proportion control module 15 in the mixing loop, and then enters the anode loop again after being evenly distributed, and enters the anode side of the alkaline electrolysis stack 4 together with part of the anode alkali liquor which does not participate in the mixing process.
Illustratively, the cathode loop comprises a cathode outlet of the alkaline electrolytic stack, a cathode loop main gas-liquid separator 5, a cathode loop alkali liquor circulating pump 11 and a cathode side of the alkaline electrolytic stack which are connected in sequence; the anode loop comprises an anode outlet of the alkaline electrolytic stack, an anode loop main gas-liquid separator 6, an anode loop alkali liquor circulating pump 12 and an anode side of the alkaline electrolytic stack which are connected in sequence.
According to the embodiment of the disclosure, in the preferred embodiment, due to the consumption of water in the electrolysis system by the electrolysis reaction and the gas-liquid separation process, pure water in the water replenishing storage module 13 enters the cathode loop main gas-liquid separator 5 after being pressurized by the water replenishing pump 14, so as to maintain the stable operation of the system.
Illustratively, the cathode loop lye mixing ratio control module 15 and the anode loop lye mixing ratio control module 16, as well as the mixing loops, together form a lye mixing ratio control module configured to be able to receive control signals from the hydrogen purity analysis module 9 and/or the oxygen purity analysis module 10 and to control the lye mixing ratio in accordance with said control signals.
Illustratively, the cathode loop alkali liquor mixing proportion control module 15 consists of n stages of parallel regulating valve sub-loops with different precision, and the regulating precision meets the requirement of delta Q c,1 <ΔQ c,2 <…<ΔQ c,n And with a set upper limit HTO of hydrogen in oxygen max Lower limit HTO min Hydrogen bias threshold delta in multi-stage oxygen HTO,i (i=0, 1, …, n) and the real-time outlet gas HTO measured by the oxygen purity analysis module 10 are control signals. When the HTO exceeds the set range, the HTO can be based on HTO and HTO max And HTO min The flow of lye through the loop in which the cathode loop lye mix ratio control module 15 is located is varied according to the flow scheme shown in figure 2. So as to dynamically adjust the mixing proportion of the alkali liquor in the cathode loop.
The anode loop alkali liquor mixing proportion control module 16 consists of n stages of parallel regulating valve sub-loops with different precision, and the regulating precision meets the requirement of delta Q a,1 <ΔQ a,2 <…<ΔQ a,n And with a set upper limit OTH of oxygen in hydrogen max Lower limit OTH min Oxygen bias threshold delta in multi-stage hydrogen OTH,i (i=0, 1, …, n) and the real-time outlet gas OTH measured by the hydrogen purity analysis module 9 are control signals. When OTH exceeds the set range, the method can be based onOTH and OTH max And OTH min The flow of lye through the loop in which the anodic loop lye mix ratio control module 16 is located is varied according to the flow scheme shown in figure 3. So as to dynamically adjust the mixing proportion of the alkaline liquor in the anode loop.
In summary, the method or the system provided in the embodiments of the present application can dynamically adjust the mixing ratio of the alkaline solution in the cathode and anode circuits based on the specific deviation between the real-time values and the set values of the HTO and OTH according to the measurement results of the oxygen and hydrogen purity analysis modules, so as to synchronously satisfy the requirements of the system operation performance and the safety characteristics according to the actual working conditions. And a multi-precision coupling alkali liquor mixing proportion control module is adopted, and the alkali liquor mixing proportion of the cathode and anode loops is dynamically adjusted with proper precision, so that the common promotion of adjusting speed, stability and accuracy is realized.
The foregoing is merely a specific implementation of the embodiments of the present application, but the protection scope of the embodiments of the present application is not limited thereto, and any person skilled in the art may easily think about changes or substitutions within the technical scope of the embodiments of the present application, and all changes and substitutions are included in the protection scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.

Claims (14)

1. A method for controlling the mixing ratio of alkaline solution in an alkaline electrolysis system, comprising the steps of:
carrying out gas-liquid separation on the mixture from the cathode outlet of the alkaline electrolytic stack to obtain cathode alkali liquor and cathode gas;
carrying out gas-liquid separation on the mixture from the anode outlet of the alkaline electrolytic stack to obtain anode alkali liquor and anode gas;
mixing a part of the anode alkali liquor with a part of the cathode alkali liquor, and adjusting the mixing proportion to obtain mixed alkali liquor;
equally distributing the mixed alkali liquor and respectively inputting the mixed alkali liquor into a cathode side and an anode side of the alkaline electrolytic stack;
wherein, the adjusting the mixing ratio comprises:
adjusting the proportion of the cathode alkali liquor in the mixed alkali liquor based on the purity of the oxygen in the anode gas, and
based on the purity of the hydrogen in the cathode gas, the proportion of the anode lye in the mixed lye is adjusted.
2. The control method according to claim 1, wherein the main component of the cathode gas is hydrogen and mixed with oxygen impurities, and the main component of the anode gas is oxygen and mixed with hydrogen impurities;
the adjusting of the mixing ratio comprises:
the amount of hydrogen in oxygen in the cathode gas and the amount of hydrogen in oxygen in the anode gas are continuously measured.
3. The control method according to claim 2, wherein said adjusting the proportion of said cathode lye in the mixed lye comprises:
setting a preset range of hydrogen in oxygen and a multi-level deviation threshold value of hydrogen in oxygen;
when the hydrogen in oxygen value exceeds the preset range of hydrogen in oxygen, obtaining a hydrogen in oxygen deviation value;
and according to the grade which is met by the hydrogen deviation value in oxygen in the hydrogen deviation threshold value in oxygen, adjusting the proportion of the cathode alkali liquor in the mixed alkali liquor according to the grade.
4. A control method according to claim 3, characterized in that when the hydrogen in oxygen deviation value exceeds a maximum level in the hydrogen in oxygen deviation threshold, an electrolysis system shutdown is controlled.
5. The control method according to claim 2, wherein said adjusting the ratio of the anode lye in the mixed lye comprises:
setting a preset hydrogen-in-oxygen range and a multi-level hydrogen-in-oxygen deviation threshold;
when the oxygen content value in the hydrogen exceeds the preset range of oxygen content in the hydrogen, obtaining an oxygen content deviation value in the hydrogen;
and according to the grade which is met by the hydrogen oxygen deviation value in the hydrogen oxygen deviation threshold, adjusting the proportion of the anode alkali liquor in the mixed alkali liquor according to the grade.
6. The control method according to claim 5, characterized in that when the hydrogen oxygen deviation value exceeds a maximum level of the hydrogen oxygen deviation threshold value, an electrolysis system stop is controlled.
7. A control method according to any one of claims 1 to 6,
the part of the cathode alkali liquor which does not participate in mixing and the equally distributed mixed alkali liquor are input to the cathode side together;
and (3) inputting the part which does not participate in mixing in the anode alkali liquor and the equally distributed mixed alkali liquor to the anode side together.
8. An alkaline electrolysis system, comprising:
an alkaline electrolysis stack (4);
the cathode loop comprises a cathode outlet of the alkaline electrolytic stack, a main gas-liquid separator (5) of the cathode loop, a cathode loop alkali liquor circulating pump (11) and a cathode side of the alkaline electrolytic stack which are connected in sequence;
the anode loop comprises an anode outlet of the alkaline electrolytic stack, an anode loop main gas-liquid separator (6), an anode loop alkali liquor circulating pump (12) and an anode side of the alkaline electrolytic stack which are connected in sequence;
a hydrogen purity analysis module (9) capable of measuring the hydrogen purity of the gas coming from the cathode loop main gas-liquid separator (5);
an oxygen purity analysis module (10) capable of measuring the oxygen purity of the gas from the anode loop main gas-liquid separator (6);
the alkali liquor mixing proportion control module is connected with the cathode loop, the anode loop and the cathode side and the anode side of the alkaline electrolysis stack (4) and can respectively acquire and mix part of alkali liquor in the cathode loop and the anode loop, and the mixed alkali liquor is equally input into the cathode side and the cathode side;
the alkali liquor mixing proportion control module is configured to receive control signals from the hydrogen purity analysis module (9) and/or the oxygen purity analysis module (10) and control the alkali liquor mixing proportion according to the control signals.
9. The alkaline electrolysis system of claim 8, wherein,
the hydrogen purity analysis module (9) is configured to generate a control signal comprising an oxygen value in hydrogen;
the oxygen purity analysis module (10) is configured to generate a control signal comprising a hydrogen quantity in oxygen.
10. The alkaline electrolysis system of claim 9, wherein the lye mixing ratio control module comprises:
a mixing circuit connected to the cathode side and the anode side, capable of mixing and equally delivering the input lye to the cathode side and the anode side;
the input end of the cathode loop alkali liquor mixing proportion control module (15) is connected with the cathode loop, the output end of the cathode loop alkali liquor mixing proportion control module is connected with the mixing loop, and the alkali liquor flow output to the mixing loop can be adjusted based on a control signal from the oxygen purity analysis module (10);
and the anode loop alkali liquor mixing proportion control module (16) is connected with the anode loop, the output end of the anode loop alkali liquor mixing proportion control module is connected with the mixing loop, and the alkali liquor flow output to the mixing loop can be regulated based on a control signal from the hydrogen purity analysis module (9).
11. Alkaline electrolysis system according to claim 10, characterized in that the cathode loop lye mix ratio control module (15) and/or the anode loop lye mix ratio control module (16) comprises a multistage parallel regulating valve sub-loop with different precision, the opening of one of the regulating valves being able to be increased or decreased based on the control signal.
12. The alkaline electrolysis system of any one of claims 8 to 11, further comprising: a water replenishing storage module (13) and a water replenishing pump (14); the water supplementing pump (14) can be used for extracting pure water in the water supplementing storage module (13) and inputting the pure water into the cathode loop main gas-liquid separator (5) in a pressurized mode when the water supplementing pump is operated.
13. The alkaline electrolysis system of any one of claims 8 to 11, further comprising:
a cathode loop auxiliary gas-liquid separator (7) connected with the hydrogen purity analysis module (9) and the cathode loop main gas-liquid separator (5);
and the anode loop auxiliary gas-liquid separator (8) is connected with the oxygen purity analysis module (10) and the anode loop main gas-liquid separator (6).
14. The alkaline electrolysis system of any one of claims 8 to 11, further comprising: a direct current power supply (3) respectively connected with the cathode side and the anode side of the alkaline electrolysis stack (4);
the direct current power supply (3) is connected with the rectifier (2), and the rectifier (2) is connected with the fluctuation renewable energy source (1).
CN202310133427.8A 2023-02-20 2023-02-20 Alkaline electrolysis system and alkali liquor mixing proportion control method thereof Pending CN116288517A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117904675A (en) * 2024-03-19 2024-04-19 浙江大学 Seawater direct hydrogen production control device and control method based on osmotic environment regulation and control

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117904675A (en) * 2024-03-19 2024-04-19 浙江大学 Seawater direct hydrogen production control device and control method based on osmotic environment regulation and control

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