A water electrolysis system and control method

Abstract

The application provides a water electrolysis system and a control method. The system comprises an electrolytic cell, a hydrogen-water separation system and a hydrogen drainage system. The hydrogen-water separation system comprises a hydrogen discharge branch and a water separation branch. The hydrogen discharge branch comprises a secondary pressure regulating valve, a primary pressure regulating valve and a hydrogen-water separator. The water separation branch comprises the hydrogen-water separator and a hydrogen-water separator drainage valve. The hydrogen drainage system comprises a water collector branch and at least one pressurizing branch. The water collector branch comprises a water collector. The pressurizing branch comprises a pressurizing valve, one end of which is connected to the water collector through a pipeline, and the other end of which is connected to a pipeline between the secondary pressure regulating valve and the primary pressure regulating valve through a pipeline. The application can ensure that the pressure of the whole system is constant during the drainage process, avoid the system pressure fluctuation caused by the action lag of the hydrogen-side pressure regulating valve and the oxygen-side pressure regulating valve, and avoid the pressure impact on the electrolytic cell to affect the service life of the electrolytic cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrolytic cell, in particular, especially to a water electrolysis system and a control method. BACKGROUND

[0002] The core structure of the electrolytic cell is an electrolytic cell unit composed of bipolar plates, conductive plates and proton exchange membranes. The specific structure of the electrolytic cell unit includes a proton exchange membrane and catalysts attached to both sides, and conductive plates are arranged on both sides. Two bipolar plates press the above structure through a sealing ring, and a plurality of electrolytic cell units are connected in series to form an electrolytic cell. Voltage is applied to both sides and water is provided to the anode. The water at the anode is decomposed to produce hydrogen ions, which combine with electrons to form hydrogen gas on the cathode side after passing through the proton exchange membrane. In this process, part of the water at the anode migrates to the cathode side with the hydrogen ions, and oxygen gas and the remaining unreacted water are mixed and discharged from the electrolytic cell.

[0003] The electrolysis system is essential equipment for hydrogen production by electrolytic cell. The stability of the electrolysis system function has a very important influence on the electrolytic cell. The electrolysis system needs to ensure the stability of the pressure during work in the performance test, industrial application and other aspects of the electrolytic cell, which has a positive effect on the stability and life of the electrolytic cell. The existing hydrogen side and oxygen side pressure control of the electrolysis system is based on the opening degree of the pressure regulating valve. The pressure will change sharply at the moment of hydrogen side drainage, and the action of the pressure regulating valve lags behind, so the system pressure fluctuates greatly. This problem will be more obvious as the hydrogen side pressure rises. Therefore, it is necessary to design a new type of water electrolysis system to avoid pressure fluctuations at the moment of hydrogen side drainage. SUMMARY

[0004] According to the technical problem of the electrolytic cell hydrogen side drainage causing system pressure fluctuation, a water electrolysis system and a control method are provided. The present application mainly increases the water collection branch and the pressure charging branch on the hydrogen water separation system, ensures that the water collection branch is isolated from other containers and pipelines on the hydrogen side at the moment of hydrogen side drainage, so as to not cause pressure change; after the drainage is completed, the pressure charging branch raises the pressure of the water collection branch to the pressure set value of the hydrogen water separation system, and then connects the water collection branch and the whole hydrogen side without causing system pressure change. The hydrogen water separation system is directly connected with the electrolytic cell, so as to avoid the pressure impact on the electrolytic cell.

[0005] The technical means adopted by the present application are as follows:

[0006] The present application provides a water electrolysis system, characterized in that it comprises an electrolytic cell, a hydrogen water separation system and a hydrogen drainage system.

[0007] The hydrogen water separation system comprises a hydrogen gas discharge branch and a water separation branch.

[0008] The hydrogen exhaust branch comprises a secondary pressure regulating valve, a primary pressure regulating valve and a hydrogen-water separator, the inlet of the hydrogen-water separator is connected with the hydrogen outlet of the electrolytic cell through a pipeline, and the gas outlet of the hydrogen-water separator is connected with the primary pressure regulating valve and the secondary pressure regulating valve through a pipeline in sequence;

[0009] The water separation branch comprises a hydrogen-water separator and a hydrogen-water separator drain valve, and the liquid outlet of the hydrogen-water separator is connected with the hydrogen-water separator drain valve through a pipeline;

[0010] The hydrogen drainage system comprises a water collecting branch and at least one pressurizing branch;

[0011] The water collecting branch comprises a water collector, and the inlet of the water collector is connected with the liquid outlet of the hydrogen-water separator through a pipeline and the hydrogen-water separator drain valve;

[0012] The pressurizing branch comprises a pressurizing valve, one end of the pressurizing valve is connected with the water collector through a pipeline, and the other end is connected with the pipeline between the secondary pressure regulating valve and the primary pressure regulating valve through a pipeline.

[0013] Further, the water electrolysis system further comprises an oxygen-water separation system for discharging oxygen and unreacted water generated by the electrolytic cell.

[0014] Further, the water collecting branch further comprises a water collector drain valve and a liquid level switch, the water collector drain valve is connected with the water collector, and the liquid level switch is installed on the water collector.

[0015] Further, the oxygen-water separation system comprises an oxygen exhaust branch and a water circulation branch, the oxygen exhaust branch is connected with the electrolytic cell, and the water circulation branch is connected with the oxygen exhaust branch and the electrolytic cell.

[0016] Further, the oxygen exhaust branch comprises an oxygen-water separator and an oxygen pressure regulating valve, the oxygen-water separator is connected with the electrolytic cell, and the oxygen pressure regulating valve is connected with the oxygen-water separator.

[0017] Further, the water circulation branch comprises a circulating pump, and the circulating pump is connected with the electrolytic cell and the oxygen-water separator of the oxygen exhaust branch respectively.

[0018] The application also provides a control method of the water electrolysis system, comprising the following steps:

[0019] Step 1, the circulating pump is operated to send the electrolyte into the electrolytic cell for electrolysis, and the generated oxygen and unreacted water enter the oxygen-water separator, the separated oxygen is regulated in pressure by the oxygen pressure regulating valve to reach a set value, so as to ensure that the pressure in the oxygen-water separation system is constant;

[0020] Step 2, hydrogen and a small amount of water produced in the electrolytic cell enter into the hydrogen-water separator, the separated hydrogen is regulated by a first regulating valve to reach the set value, so as to ensure the constant pressure in the hydrogen-water separation system and the hydrogen drainage system;

[0021] Step 3, with the rising of the liquid level in the water collector, when reaching the liquid level switch position, the hydrogen-water separator drainage valve is closed and the water collector drainage valve is opened to drain water, at this time, the pressure charging valve is in the closed state and the second regulating valve is in the open state;

[0022] Step 4, when the drainage reaches the predetermined time, the water collector drainage valve is closed, the pressure of the second regulating valve is adjusted to be equal to that of the first regulating valve, the pressure charging valve is opened to charge the water collector;

[0023] Step 5, when the pressure in the water collector is equal to that in the hydrogen-water separation system, the pressure charging valve is closed, the water collector drainage valve and the second regulating valve are opened, at this time, the water in the hydrogen-water separator flows into the water collector under the action of gravity, the water collector and the hydrogen-water separator are in the same pressure, at the moment when the water collector drainage valve is opened, the pressure fluctuation of the hydrogen-water separation system and the hydrogen drainage system is extremely small.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] 1. The hydrogen-water separation system of the present application is isolated from the water collector during drainage, the internal effective space is unchanged, and the pressure of the whole system can be kept unchanged during the drainage process.

[0026] 2. After the drainage is completed, the generated hydrogen is used to recharge the water collector, so that the pressure of the water collector is equal to that of the hydrogen-water separation system, and then the hydrogen-water separator and the water collector are connected, so that the pressure of the whole system is kept unchanged after the drainage is completed.

[0027] 3. The pressure of the electrolytic system is kept unchanged during the whole process, so that the pressure fluctuation caused by the lag of the hydrogen-side regulating valve and the oxygen-side regulating valve can be avoided, and the pressure impact on the electrolytic cell can be avoided to affect the service life.

[0028] 4. The method for ensuring the accurate control of the pressure of the system is completed by the opening and closing or adjustment of the electric valve, and the control logic is easy to realize.

[0029] Based on the above reasons, the present application can be widely popularized in the field of electrolysis. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0031] Figure 1 The system schematic diagram is shown in the specific embodiment of the present application.

[0032] In the figure: 1, electrolytic cell; 2, circulating pump; 3, oxygen water separator; 4, oxygen pressure regulating valve; 5, secondary pressure regulating valve; 6, primary pressure regulating valve; 7, hydrogen water separator; 8, hydrogen water separator drain valve; 9, water collector; 10, water collector drain valve; 11, pressure charging valve; 12, liquid level switch. Specific embodiment

[0033] It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0034] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, operation, device, component and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples provided herein are not intended to limit the scope of the application. It should also be understood that the size of the various parts shown in the figures can not be to scale, and that the dimensions of the parts can be arbitrarily enlarged or reduced for the sake of clarity. Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the specification, where appropriate. In all examples shown and discussed herein, any specific value should be interpreted as merely an example, and not as a limitation. Thus, other examples of the exemplary embodiments can have different values. It should be noted that like reference numerals and letters in the following drawings represent similar items, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0037] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate and imply that the devices or elements referred to must have a particular orientation or be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the scope of protection of the present application: the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component itself.

[0038] Embodiment 1

[0039] The present application provides a water electrolysis system, including electrolytic tank 1, oxygen water separation system, hydrogen water separation system, hydrogen drainage system, oxygen water separation system includes oxygen discharge branch, water circulation branch, hydrogen water separation system includes hydrogen discharge branch, water separation branch, hydrogen drainage system includes water collection branch, pressure charging branch, oxygen discharge branch is connected with electrolytic tank 1, water circulation branch is connected with oxygen discharge branch and electrolytic tank 1, hydrogen discharge branch is connected with electrolytic tank 1, water separation branch is connected with hydrogen discharge branch, water collection branch is connected with water separation branch, pressure charging branch is connected with hydrogen discharge branch and water collection branch.

[0040] Oxygen discharge branch is composed of oxygen water separator 3, oxygen pressure regulating valve 4 and pipeline, water circulation branch is composed of circulating pump 2 and pipeline, oxygen water separator 3 is connected with electrolytic tank 1 through pipeline, oxygen pressure regulating valve 4 is connected with oxygen water separator 3 through pipeline, circulating pump 2 is connected with oxygen water separator 3 through pipeline, and is connected with electrolytic tank 1 through pipeline at the same time.

[0041] Hydrogen discharge branch is composed of primary pressure regulating valve 6, secondary pressure regulating valve 5, hydrogen water separator 7 and pipeline, water separation branch is composed of hydrogen water separator drain valve 8 and pipeline, the inlet of hydrogen water separator 7 is connected with the hydrogen outlet of electrolytic tank 1 through pipeline, primary pressure regulating valve 6 is connected with the hydrogen outlet of hydrogen water separator 7 through pipeline, secondary pressure regulating valve 5 is connected with primary pressure regulating valve 6 through pipeline. Hydrogen water separator drain valve 8 is connected with the liquid outlet of hydrogen water separator 7 through pipeline.

[0042] Water collection branch is composed of water collector 9, water collector drain valve 10, liquid level switch 12 and pipeline, and pressure charging branch is composed of pressure charging valve 11 and pipeline. The inlet of water collector 9 is connected with hydrogen water separator drain valve 8 through pipeline, water collector drain valve 10 is connected with water collector 9 through pipeline, liquid level switch 12 is installed on water collector 9, one end of pressure charging valve 11 is connected with water collector drain valve 10 through pipeline, and the other end is connected on the pipeline between secondary pressure regulating valve 5 and primary pressure regulating valve 6 through pipeline.

[0043] The electrolytic cell 1 is connected to direct current, and the oxygen and water produced by electrolysis enter the oxygen-water separator 3. The circulating pump 2 in the water circulating branch absorbs water from the oxygen-water separator 3 and pumps the separated water into the electrolytic cell 1, and the produced oxygen and unreacted water flow back to the oxygen-water separator 3, wherein the separated oxygen flows into the oxygen pressure regulating valve 4 in the oxygen discharge branch and is discharged.

[0044] The hydrogen and a small amount of water produced by the electrolytic cell 1 flow into the hydrogen-water separator 7 in the hydrogen discharge branch, wherein the separated hydrogen flows into the primary pressure regulating valve 6 and the secondary pressure regulating valve 5 in the hydrogen discharge branch and is discharged; the water separated in the hydrogen-water separator 7 flows through the hydrogen-water separator drain valve 8 and enters the water collector 9 in the water collecting branch; the water in the water collector 9 is discharged through the water collector drain valve 10 after the liquid level switch 12 sends a signal; the hydrogen discharged from the primary pressure regulating valve 6 can enter the water collector 9 through the pressure charging valve 11 in the pressure charging branch before the secondary pressure regulating valve 5.

[0045] The system separates the hydrogen-water separation system from the water collector during water drainage, avoiding pressure fluctuations in the system; after the water drainage is completed, the produced hydrogen backflow is used to connect the hydrogen-water separator and the water collector after the hydrogen-water separation system is isobaric, avoiding pressure fluctuations in the hydrogen-water separation system, and further avoiding pressure impact on the electrolytic cell. This method precisely controls the constant pressure during the entire water drainage process.

[0046] Embodiment 2

[0047] As shown in Figure 1 The present application provides a water electrolysis system, which comprises an electrolytic cell 1, a circulating pump 2, an oxygen-water separator 3, an oxygen pressure regulating valve 4, a secondary pressure regulating valve 5, a primary pressure regulating valve 6, a hydrogen-water separator 7, a hydrogen-water separator drain valve 8, a water collector 9, a water collector drain valve 10, a pressure charging valve 11, and a liquid level switch 12; in addition, some necessary connecting pipelines are included.

[0048] The control method of the water electrolysis system of the present application comprises the following steps:

[0049] Step 1: The circulating pump 2 operates to send the electrolyte into the electrolytic cell 1 for electrolysis, and the produced oxygen and unreacted water enter the oxygen-water separator 3, wherein the separated oxygen is pressure-regulated by the oxygen pressure regulating valve 4 to reach a set value, ensuring that the pressure in the oxygen-water separation system is constant;

[0050] Step 2: The hydrogen and a small amount of water produced by the electrolytic cell 1 enter the hydrogen-water separator 7, wherein the separated hydrogen is pressure-regulated by the primary pressure regulating valve 6 to reach a set value, ensuring that the pressure in the hydrogen-water separation system and the hydrogen drainage system is constant;

[0051] Step 3, as the water level in the water collector 9 rises, when the water level reaches the position of the water level switch 12, the hydrogen water separator drain valve 8 is closed, the water collector drain valve 10 is opened to drain water, at this time the pressure charging valve 11 is in the closed state, and the secondary pressure regulating valve 5 is in the open state;

[0052] Step 4, when the water drainage reaches a predetermined time, the water collector drain valve 10 is closed, the pressure of the secondary pressure regulating valve 5 is adjusted to be equal to that of the primary pressure regulating valve 6, the pressure charging valve 11 is opened to charge the water collector 9 with pressure;

[0053] Step 5, when the pressure in the water collector 9 is equal to that of the hydrogen water separation system, the pressure charging valve 11 is closed, the water collector drain valve 10 and the secondary pressure regulating valve 5 are opened, at this time the water in the hydrogen water separator 7 flows into the water collector 9 under the action of gravity, since the water collector 9 and the hydrogen water separator 7 are at the same pressure, therefore the pressure fluctuation of the hydrogen water separation system and the hydrogen drainage system is extremely small at the moment when the water collector drain valve 10 is opened.

[0054] When the system is working, the oxygen side pipeline pressure P 氧 is set by using the oxygen pressure regulating valve 4. The hydrogen side pipeline pressure P 氢 is set by using the primary pressure regulating valve 6, the secondary pressure regulating valve 5 is fully opened, the hydrogen water separator drain valve 8 is opened, and the water collector drain valve 10 and the pressure charging valve 11 are closed. The water in the hydrogen water separator 7 flows into the water collector 9 through the hydrogen water separator drain valve 8, when the water level reaches the set position of the water level switch 12, the hydrogen water separator drain valve 8 is closed, the water collector drain valve 10 and the pressure charging valve 11 are opened, at this time the water collector 9 is drained, but the pressure P 氢 before the primary pressure regulating valve 6 remains constant. After the water in the water collector 9 is drained, the water collector drain valve 10 is closed, the pressure of the secondary pressure regulating valve 5 is set to P 氢 , the pressure charging valve 11 is opened, at this time hydrogen is injected into the water collector 9, after the pressure reaches the set value, the pressure charging valve 11 is closed, the hydrogen water separator drain valve 8 and the secondary pressure regulating valve 5 are opened, at this time the hydrogen water separator 7 and the water collector 9 are at the same pressure, the water flows into the water collector 9 relying on gravity, and the hydrogen side pipeline pressure P 氢 remains constant.

[0055] When working, there is no pressure fluctuation before the primary pressure regulating valve 6 during the moment of hydrogen side pipeline drainage and the process of increasing the pressure of the water collector 9, especially under high pressure (≥3.5 MPa) of the system, the pressure stabilizing effect is obvious.

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A water electrolysis system, characterized by, Comprise: Electrolytic cell (1), hydrogen water separation system and hydrogen drainage system; The hydrogen water separation system comprises a hydrogen discharge branch and a water separation branch; The hydrogen discharge branch comprises a secondary pressure regulating valve (5), a primary pressure regulating valve (6) and a hydrogen water separator (7), the inlet of the hydrogen water separator (7) is connected with the hydrogen outlet of the electrolytic cell (1) through a pipeline, and the gas outlet of the hydrogen water separator (7) is connected with the primary pressure regulating valve (6) and the secondary pressure regulating valve (5) through a pipeline in sequence; The water separation branch comprises the hydrogen water separator (7) and a hydrogen water separator drainage valve (8), and the liquid outlet of the hydrogen water separator (7) is connected with the hydrogen water separator drainage valve (8) through a pipeline; The hydrogen drainage system comprises a water collecting branch and at least one pressurizing branch; The water collecting branch comprises a water collector (9), and the inlet of the water collector (9) is connected with the liquid outlet of the hydrogen water separator (7) through a pipeline and the hydrogen water separator drainage valve (8); The pressurizing branch comprises a pressurizing valve (11), one end of the pressurizing valve (11) is connected with the water collector (9) through a pipeline, and the other end is connected on the pipeline between the secondary pressure regulating valve (5) and the primary pressure regulating valve (6) through a pipeline; The water electrolysis system further comprises an oxygen water separation system for discharging oxygen and unreacted water generated by the electrolytic cell (1); The water collecting branch further comprises a water collector drainage valve (10) and a liquid level switch (12), the water collector drainage valve (10) is connected with the water collector (9), and the liquid level switch (12) is installed on the water collector (9).

2. The water electrolysis system of claim 1, wherein, The oxygen water separation system comprises an oxygen discharge branch and a water circulation branch, the oxygen discharge branch is connected with the electrolytic cell (1), and the water circulation branch is connected with the oxygen discharge branch and the electrolytic cell (1).

3. The water electrolysis system of claim 2, wherein, The oxygen discharge branch comprises an oxygen water separator (3) and an oxygen pressure regulating valve (4), the oxygen water separator (3) is connected with the electrolytic cell (1), and the oxygen pressure regulating valve (4) is connected with the oxygen water separator (3).

4. The water electrolysis system of claim 2, wherein, The water circulation branch comprises a circulating pump (2), and the circulating pump (2) is connected with the electrolytic cell (1) and the oxygen water separator (3) of the oxygen discharge branch respectively.

5. A control method of a water electrolysis system as claimed in any one of claims 1 to 4, characterized in that, Comprise the following steps: Step 1, the circulating pump (2) operates, the electrolyte is sent into the electrolytic cell (1) for electrolysis, the generated oxygen and unreacted water enter the oxygen water separator (3), the separated oxygen is pressure-regulated through the oxygen pressure regulating valve (4), reaches the set value, and the pressure in the oxygen water separation system is constant; Step 2, the hydrogen and a small amount of water generated in the electrolytic cell (1) enter the hydrogen water separator (7), the separated hydrogen is pressure-regulated through the primary pressure regulating valve (6), reaches the set value, and the pressure in the hydrogen water separation system and the hydrogen drainage system is constant; Step 3, as the liquid level in the water collector (9) rises continuously, when reaching the position of the liquid level switch (12), the hydrogen water separator drainage valve (8) is closed, the water collector drainage valve (10) is opened for drainage, and the pressurizing valve (11) is in a closed state and the secondary pressure regulating valve (5) is in an open state; Step 4, when the water reaches the predetermined time, the water collector drain valve (10) is closed, the secondary pressure regulating valve (5) pressure is adjusted to be equal to the primary pressure regulating valve (6), the pressure charging valve (11) is opened, and the water collector (9) is charged; Step 5, when the water collector (9) pressure is equal to the hydrogen water separation system, the pressure charging valve (11) is closed, the water collector drain valve (10) and the secondary pressure regulating valve (5) are opened, at this time, the water in the hydrogen water separator (7) flows into the water collector (9) under the action of gravity, the water collector (9) and the hydrogen water separator (7) are equal in pressure, and at the moment when the water collector drain valve (10) is opened, the pressure fluctuation of the hydrogen water separation system and the hydrogen water drainage system is extremely small.

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