Adjustment method of electrolyte concentration balance automatic adjustment system for hydrogen production by electrolysis of water

Abstract

The present application discloses a method for adjusting an automatic electrolyte concentration balance system for hydrogen production by electrolysis of water. The method belongs to the field of electrolysis process technology and includes an electrolytic cell containing an electrolyte and connected to a hydrogen gas-liquid separator and an oxygen gas-liquid separator. The hydrogen gas-liquid separator, the oxygen gas-liquid separator, and the electrolytic cell are all connected to a premixed liquid storage tank containing premixed electrolyte. The premixed liquid storage tank is connected to a pure water storage tank, and a pure water solenoid valve is provided between the pure water storage tank and the premixed liquid storage tank, through which the pure water is limited. The method has the following advantages: the electrolyte concentration in the electrolytic cell is monitored. When the electrolyte concentration changes due to changes in process parameters (temperature, pressure, liquid level, current density) during the electrolysis process, an intelligent algorithm is used to control the addition of a specific concentration of premixed electrolyte to replenish the pure water and electrolyte consumed by the electrolysis, thereby dynamically adjusting and balancing the electrolyte concentration in the electrolytic cell to maintain a constant liquid level and electrolyte concentration.

Description

Technical Field

[0001] The invention discloses a method for regulating an automatic regulating system for electrolyte concentration balance in hydrogen production by electrolyzing water, and belongs to the technical field of electrolysis technology. Background Art

[0002] During the electrolysis of water to produce hydrogen, direct current is passed through the electrolyte in the electrolyzer. Water molecules undergo an electrochemical reaction at the electrodes, generating hydrogen and hydroxide ions at the cathode. The hydroxide ions migrate through the diaphragm to the anode, where the hydroxide ions lose electrons to produce oxygen. The role of the electrolyte in the electrolysis of water to produce hydrogen is mainly to provide ion conduction, reduce power consumption, protect the electrodes, and extend the service life of the electrolyzer.

[0003] Commonly used electrolyte components mainly include potassium hydroxide (KOH) or sodium hydroxide (NaOH). The mass concentration of potassium hydroxide (KOH) is usually 30%, and the mass concentration of sodium hydroxide (NaOH) is generally 26%.

[0004] Electrolyte concentration is a critical parameter in the hydrogen production process by water electrolysis. Fluctuations in the electrolyzer electrolyte concentration can occur easily due to adjustments in process parameters or occasional interference. If these fluctuations persist, they can be harmful. Excessively high electrolyte concentrations can corrode the asbestos membrane, precipitate crystals, and clog the liquid and gas lines, causing the electrolyzer to malfunction. Excessively low electrolyte concentrations can increase power consumption, weaken metal passivation, reduce gas purity, and increase equipment corrosion.

[0005] During the electrolysis process, the electrolyte level must be kept constant. The electrolyte serves as the medium for ion conduction. Insufficient electrolyte levels can partially expose the electrodes to air, reducing the surface area available for reaction and lowering electrolysis efficiency. Furthermore, changes in electrolyte level alter the resistance between the electrodes, causing electrolytic cell voltage fluctuations. To maintain a constant current, the power supply must frequently adjust its output, potentially increasing energy consumption and impacting equipment life. Therefore, the electrolysis process incorporates electrolyte recycling and water replenishment systems. These replenishment systems add water to the electrolytic cell to maintain a constant electrolyte level. The hydrogen and oxygen produced by electrolysis mix with the electrolyte vapor and enter a gas-liquid separator. The separated hydrogen and oxygen are then collected and stored, while the resulting high-concentration electrolyte flows back into the electrolytic cell for recycling.

[0006] The existing technology has the following disadvantages:

[0007] Existing technologies are unable to eliminate the impact of occasional interference factors on the control system, causing system oscillation or even deterioration. For example, voltage fluctuations reduce the current density of the electrolytic cell, reduce the pressure of the electrolytic cell, slow down the flow rate of the electrolyte recovered by gas-liquid separation, reduce the reflux of high-concentration electrolyte, and lower the electrolyte concentration of the entire electrolytic cell. The conductivity is reduced, which slows down the electrolytic cell reaction and further reduces the pressure, causing positive feedback deterioration of the electrolytic reaction and further lowering the electrolyte concentration of the electrolytic cell.

[0008] Uncertain factors in gas-liquid separation and reflux: The concentration of the electrolyte in the electrolytic cell fluctuates, causing corrosion and blockage of the electrolytic equipment and reduced gas purity. The existing technology only controls the amount of water replenishment to keep the liquid level in the electrolytic cell constant. In theory, electrolysis of water only consumes water and does not consume electrolytes. It is sufficient to replenish water to maintain the liquid level in the electrolytic cell. In actual production, the hydrogen and oxygen produced by electrolysis are mixed with the electrolyte vapor. After entering the gas-liquid separator, the hydrogen and oxygen are separated and enter the dryer. The electrolyte vapor is liquefied and refluxed, entering the electrolytic cell for secondary circulation. Due to the fluctuation and oscillation of process parameters during the production process, the concentration and amount of the refluxed electrolyte change. The instability of the amount of refluxed electrolyte causes the concentration of the electrolytic cell to fluctuate.

[0009] The adjustment of production capacity causes the electrolyte concentration of the electrolyzer to fluctuate, resulting in corrosion and blockage of the electrolysis equipment and reduced gas purity. The existing technology cannot dynamically adjust the electrolyte concentration. When the production capacity of hydrogen production by electrolysis of water is adjusted, the process parameters need to be modified to increase or decrease the power of the electrolyzer. The adjustment of the process parameters breaks the balance of the electrolyte concentration and causes the electrolyte concentration to change. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to address the above shortcomings and provide an automatic adjustment system and method for the electrolyte concentration balance of hydrogen production by electrolysis of water, which monitors the electrolyte concentration inside the electrolytic cell. When the electrolyte concentration changes due to changes in process parameters (temperature, pressure, liquid level, current density) during the electrolysis process, the system controls the addition of premixed electrolyte of a specific concentration through an intelligent algorithm to replenish the pure water and electrolyte consumed in the electrolysis, and dynamically adjusts the electrolyte concentration of the electrolytic cell to maintain a constant liquid level and electrolyte concentration.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0012] An automatic regulating system for the balance of electrolyte concentration for producing hydrogen by electrolysis of water comprises an electrolytic cell in which electrolyte is placed and the electrolytic cell is connected to a hydrogen gas-liquid separator and an oxygen liquid separator;

[0013] The hydrogen-liquid separator, the oxygen-liquid separator and the electrolyzer are all connected to a premixed liquid storage tank, the premixed liquid storage tank contains premixed electrolyte, the premixed liquid storage tank is connected to a pure water storage tank, a pure water solenoid valve is provided between the pure water storage tank and the premixed liquid storage tank, and the pure water is limited by the pure water solenoid valve;

[0014] The electrolytic recovery liquid generated by the gas-liquid separation of the electrolytic cell flows into the premixed liquid storage tank from the bottom of the hydrogen gas-liquid separator and the bottom of the oxygen liquid separator respectively. Pure water dilutes the high-concentration electrolytic recovery liquid and mixes it to form a premixed electrolyte of a certain concentration, which then flows back to the electrolytic cell. By controlling the pure water flow rate, the electrolyte concentration can be dynamically adjusted.

[0015] Furthermore, a rehydration solenoid valve and a rehydration pump are provided between the electrolytic cell and the premixed liquid storage tank;

[0016] A conductivity tester is installed inside the electrolytic cell to obtain the concentration of the electrolyte in the electrolytic cell;

[0017] A liquid level sensor is installed inside the electrolytic cell to obtain the liquid level of the electrolyte in the electrolytic cell;

[0018] The electrolyte concentration balance automatic adjustment system further comprises an electronic control module, which is connected to the pure water solenoid valve, the liquid replenishment solenoid valve, the liquid replenishment pump, the liquid level sensor and the conductivity tester.

[0019] A method for adjusting an automatic adjustment system for an electrolyte concentration balance for hydrogen production by electrolysis of water comprises the following steps:

[0020] Step 1: The liquid level sensor in the electrolytic cell detects the liquid level in the electrolytic cell. The electronic control module replenishes the corresponding premixed electrolyte from the premixed liquid storage tank according to the electrolyte missing in the electrolytic cell. The premixed electrolyte is continuously replenished as the electrolyte in the electrolytic cell is consumed, so that the electrolyte in the electrolytic cell is always maintained at the same liquid level;

[0021] Step 2: The conductivity tester in the electrolytic cell continuously detects the electrolyte concentration in the electrolytic cell, and adjusts the action of the pure water solenoid valve according to the electrolyte concentration. If the electrolyte concentration is higher than the standard concentration, the conduction frequency of the pure water solenoid valve is gradually increased to increase the pure water inlet. If the electrolyte concentration is lower than the standard concentration, the conduction frequency of the pure water solenoid valve is gradually reduced to reduce the pure water inlet.

[0022] Furthermore, the step 2 specifically includes the following steps:

[0023] Step 1: Get data;

[0024] Step 1.1: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the integral value A of the concentration change of the current electrolyte concentration relative to the standard concentration within the k sampling time;

[0025] Step 1.2: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the concentration change rate value B of the current electrolyte concentration relative to the standard concentration within the k sampling time;

[0026] Step 1.3: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the difference D between the current electrolyte concentration and the standard concentration at the end of the k sampling time;

[0027] The integral value of the concentration change , j is the number of sampling cycles within the k sampling time, and D(j) is the difference between the electrolyte concentration and the standard concentration in the jth sampling cycle.

[0028] Furthermore, the step 2 specifically further includes the following steps:

[0029] Step 2: Determine the adjustment plan;

[0030] Introduce the proportional differential integral comprehensive regulation method to adjust the pure water solenoid valve:

[0031] E=K1*D+K2*A+K3*B;

[0032] in:

[0033] E is the conduction frequency of the pure water solenoid valve;

[0034] K1, K2, and K3 are system adjustment coefficients;

[0035] K1*D is a proportional adjustment item, which proportionally adjusts the conduction time of the pure water solenoid valve according to the deviation between the current electrolyte concentration of the electrolytic cell and the standard concentration;

[0036] K2*A is the integral adjustment item, which is used to eliminate the steady-state error of the system. It will integrate the concentration deviation. As time accumulates, the integral item will gradually increase, causing the conduction time of the pure water solenoid valve to gradually increase to ensure that the standard concentration can be reached in the end;

[0037] K3*B is the differential adjustment item, which adjusts the conduction time of the pure water solenoid valve in advance according to the change rate of the concentration deviation. When the concentration changes too quickly, the differential link will make corresponding adjustments to the conduction time of the pure water solenoid valve to prevent excessive concentration adjustment and stabilize the adjustment process.

[0038] Since the amount of pure water passing through the pure water solenoid valve within one conduction time is a fixed value, the pure water flow rate can be changed by changing the conduction frequency E of the pure water solenoid valve; by adjusting the size of the pure water flow rate, the mixing ratio of pure water in the premixed electrolyte can be changed, and the concentration of the premixed electrolyte mixture in the premixed liquid storage tank can be adjusted;

[0039] As the E value increases, the proportion of pure water added increases and the concentration of the premixed electrolyte decreases; as the E value decreases, the proportion of pure water added decreases and the concentration of the premixed electrolyte increases.

[0040] Furthermore, the step 2 specifically further includes the following steps:

[0041] Step 3: System tuning, calculation of adjustment coefficient;

[0042] Assume that the standard concentration of the electrolyte in the electrolytic cell is S_C, and its value is obtained by the conductivity tester installed inside the electrolytic cell;

[0043] Assume that the current concentration of the electrolyte in the electrolytic cell is C_C, whose value is obtained by the conductivity meter installed inside the electrolytic cell;

[0044] Calculate the difference between the current concentration and the standard addition concentration D=C_C-S_C;

[0045] First, set K2 and K3 to zero, then: E=K1*D+0*A+0*B=K1*D;

[0046] Gradually increase K1 from zero until the system output oscillates with equal amplitude. Note the K1 value at this time, define the K1 value at this time as Ku, and note the system oscillation period.

[0047] Furthermore, the step 3 further includes the following steps:

[0048] Only set K2 to zero, and multiply Ku by the Ziegler-Nichols coefficient 0.6, that is, K1=0.6*Ku. Within one oscillation cycle, obtain the concentration change rate value B, and obtain the difference D between the current concentration and the standard addition concentration, and substitute it into the formula:

[0049] E=K1*D+K3*B=0.6*Ku*D+K3*B;

[0050] Since K1, D, and B are known, by gradually increasing K3 from zero, the E value changes until the system stops oscillating. Note the K3 value at this time. Although the system is stable at this time, the output has a stable deviation △D.

[0051] Furthermore, the step 3 further includes the following steps:

[0052] Set a sampling period, obtain the values ​​of D, A, and B, and substitute them together with K1 and K3 into the formula: E=K1*D+K2*A+K3*B;

[0053] Increase or decrease the K2 value, and the E value changes, so that the above-mentioned stable deviation △D decreases and approaches zero, and record the K2 value at this time;

[0054] At this point, the system is stable and does not oscillate, the deviation is close to zero, and the adjustment coefficients K1, K2, and K3 are adjusted.

[0055] Furthermore, the step 2 specifically further includes the following steps:

[0056] Step 4: concentration adjustment;

[0057] After the pure water solenoid valve conduction frequency E value is executed, the electrolyte concentration will not change immediately due to the hysteresis of the system;

[0058] By continuously performing n sampling times and constantly revising the conduction frequency E value of the pure water solenoid valve according to A, B, and D, the electrolyte concentration of the balanced electrolytic cell can be dynamically adjusted to keep it consistent with the electrolyte concentration of the electrolytic cell;

[0059] The electronic control module continuously compares the new concentration data with the standard concentration and adjusts the conduction frequency and time of the pure water solenoid valve until the concentration reaches the target value;

[0060] When the concentration approaches the target value, the electronic control module automatically adjusts to gradually reduce the conduction frequency and time of the pure water solenoid valve to avoid excessive concentration adjustment.

[0061] The present invention adopts the above technical solution, which has the following technical effects compared with the prior art:

[0062] Monitor the electrolyte concentration inside the electrolytic cell. When the electrolyte concentration changes due to changes in process parameters (temperature, pressure, liquid level, current density) during the electrolysis process, the intelligent algorithm controls the addition of premixed electrolyte of a specific concentration to replenish the pure water and electrolyte consumed in the electrolysis, and dynamically adjusts the electrolyte concentration in the electrolytic cell to maintain a constant liquid level and electrolyte concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0064] Figure 1 Schematic diagram of the structure of the automatic adjustment system for electrolyte concentration balance in the present invention;

[0065] Among them, 1-electrolyzer, 2-hydrogen gas-liquid separator, 3-oxygen liquid separator, 4-deoxygenator, 5-dryer, 6-hydrogen storage tank, 7-premixed liquid storage tank, 8-pure water storage tank, 9-liquid replenishing solenoid valve, 10-liquid replenishing pump, 11-pure water solenoid valve. DETAILED DESCRIPTION

[0066] Examples, such as Figure 1As shown, an automatic adjustment system for electrolyte concentration balance for producing hydrogen by electrolysis of water includes an electrolytic cell 1, in which electrolyte is placed, the electrolytic cell 1 is connected to a hydrogen gas-liquid separator 2 and an oxygen liquid separator 3, the hydrogen gas-liquid separator 2 is connected to a deoxidizer 4, the deoxidizer 4 is connected to a dryer 5, and the dryer 5 is connected to a hydrogen storage tank 6.

[0067] The hydrogen-liquid separator 2, the oxygen-liquid separator 3 and the electrolyzer 1 are all connected to a premixed liquid storage tank 7, which contains premixed electrolyte. The premixed liquid storage tank 7 is connected to a pure water storage tank 8. A liquid replenishing solenoid valve 9 and a liquid replenishing pump 10 are provided between the electrolyzer 1 and the premixed liquid storage tank 7. A pure water solenoid valve 11 is provided between the pure water storage tank 8 and the premixed liquid storage tank 7. Pure water is limited by the pure water solenoid valve 11 and flows into the premixed liquid storage tank 7 at a set flow rate.

[0068] A conductivity tester is installed inside the electrolytic cell 1 to obtain the concentration of the electrolyte in the electrolytic cell.

[0069] A liquid level sensor is installed inside the electrolytic cell 1 to obtain the liquid level of the electrolyte in the electrolytic cell.

[0070] The electrolytic recovery liquid generated by the gas-liquid separation of the electrolytic cell 1 flows into the premixed liquid storage tank from the bottom of the hydrogen gas-liquid separator and the bottom of the oxygen liquid separator respectively. Pure water dilutes the high-concentration electrolytic recovery liquid and mixes it to form a premixed electrolyte of a certain concentration, which then flows back to the electrolytic cell 1. By controlling the pure water flow rate, the electrolyte concentration can be dynamically adjusted.

[0071] The electrolyte concentration balance automatic adjustment system further comprises an electronic control module, which is connected to the pure water solenoid valve, the liquid replenishment solenoid valve, the liquid replenishment pump, the liquid level sensor and the conductivity tester.

[0072] During the electrolysis process, pure water is consumed to generate hydrogen and oxygen, and part of the electrolyte enters the gas-liquid separator along with the hydrogen and oxygen. Due to the above reasons, the pure water and electrolyte in the electrolytic cell gradually decrease, causing the electrolytic cell liquid level to decrease and the concentration to change. By real-time monitoring of the electrolyte concentration in the electrolytic cell, the electronic control module continuously samples and calculates the changing trend, standard deviation, and changing speed of the electrolyte concentration. The electronic control module weights these three variables with coefficients and converts the weighted results into the action parameters of the pure water solenoid valve. The adjustment of the action parameters of the pure water solenoid valve can change the proportion of pure water in the premixed electrolyte, thereby changing the concentration of the premixed electrolyte. The change in the electrolyte concentration of the electrolytic cell can be dynamically balanced by adding premixed electrolyte of appropriate concentration to the electrolytic cell.

[0073] A method for adjusting an automatic adjustment system for an electrolyte concentration balance for hydrogen production by electrolysis of water comprises the following steps:

[0074] Step 1: The liquid level sensor in the electrolytic cell detects the liquid level of the electrolytic cell. The electronic control module replenishes the corresponding premixed electrolyte from the premixed liquid storage tank according to the missing electrolyte in the electrolytic cell. The premixed electrolyte is continuously replenished as the electrolyte in the electrolytic cell is consumed, so that the electrolyte in the electrolytic cell is always maintained at the same liquid level.

[0075] Step 2: Use the conductivity tester in the electrolytic cell to continuously detect the electrolyte concentration in the electrolytic cell, and adjust the action of the pure water solenoid valve according to the electrolyte concentration. If the electrolyte concentration is higher than the standard concentration, gradually increase the conduction frequency of the pure water solenoid valve to increase the pure water inlet. If the electrolyte concentration is lower than the standard concentration, gradually reduce the conduction frequency of the pure water solenoid valve to reduce the pure water inlet. The specific adjustment steps are as follows:

[0076] Step 1: Get the data.

[0077] Step 1.1: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the integral value A of the concentration change of the current electrolyte concentration relative to the standard concentration within the k sampling time;

[0078] Step 1.2: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the concentration change rate value B of the current electrolyte concentration relative to the standard concentration within the k sampling time;

[0079] Step 1.3: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the difference D between the current electrolyte concentration and the standard concentration at the end of the k sampling time;

[0080] The integral value of the concentration change , j is the number of sampling cycles within the k sampling time, D(j) is the difference between the electrolyte concentration and the standard concentration in the j-th sampling cycle. For example, assuming that the sampling cycle △t is 1 minute, and the concentration deviations within k of 5 minutes are 3%, 4%, 4.5%, 4.8%, and 5%, respectively, then A=(3%+4%+4.5%+4.8%+5%)×1=21.3%.

[0081] Concentration change rate value , D(k-1) is the difference between the current electrolyte concentration and the standard concentration at the end of k-1 sampling time.

[0082] Step 1.1, step 1.2, and step 1.3 are performed synchronously within one unit sampling period.

[0083] Step 2: Determine the adjustment plan;

[0084] The difficulty in accurately controlling a hysteresis system is that the output does not change immediately after the input is changed, but rather takes a certain amount of time to change. This makes it difficult to control the value of the input.

[0085] If the input changes too much, the output will overshoot and oscillate. If the input changes too little, the output will be slow to respond. When the system finally stabilizes, large errors are found.

[0086] In order to solve the above problems, the proportional differential integral comprehensive regulation method is introduced to adjust the pure water solenoid valve:

[0087] E=K1*D+K2*A+K3*B;

[0088] in:

[0089] E is the conduction frequency of the pure water solenoid valve;

[0090] K1, K2, and K3 are system adjustment coefficients.

[0091] K1*D is a proportional adjustment item, which proportionally adjusts the conduction time of the pure water solenoid valve according to the deviation between the current electrolyte concentration of the electrolytic cell and the standard concentration.

[0092] K2*A is the integral adjustment item, which is used to eliminate the steady-state error of the system. It will integrate the concentration deviation. As time accumulates, the integral item will gradually increase, causing the conduction time of the pure water solenoid valve to gradually increase to ensure that the standard concentration can be reached in the end.

[0093] K3*B is the differential adjustment item, which adjusts the conduction time of the pure water solenoid valve in advance according to the change rate of the concentration deviation. When the concentration changes too quickly, the differential link will make corresponding adjustments to the conduction time of the pure water solenoid valve to prevent excessive concentration adjustment and stabilize the adjustment process.

[0094] Since the amount of pure water passing through the pure water solenoid valve within one conduction time is a fixed value, the pure water flow rate can be changed by changing the conduction frequency E of the pure water solenoid valve; by adjusting the size of the pure water flow rate, the mixing ratio of pure water in the premixed electrolyte can be changed, and the concentration of the premixed electrolyte mixture in the premixed liquid storage tank can be adjusted.

[0095] As the E value increases, the proportion of pure water added increases and the concentration of the premixed electrolyte decreases; as the E value decreases, the proportion of pure water added decreases and the concentration of the premixed electrolyte increases.

[0096] Step 3: System tuning, calculation of adjustment coefficient;

[0097] The numerical values ​​of the adjustment coefficients K1, K2, and K3 determine whether the system adjustment performance is good or not.

[0098] K1 corresponds to the proportional adjustment item. If the value of K1 is too large, the system will oscillate violently and become unstable, which is manifested as the concentration of the electrolyte in the electrolytic cell fluctuating.

[0099] K2 corresponds to the integral adjustment item. If the value of K2 is too large, it will lead to the steady-state error of the system, which is manifested as the stable deviation of the electrolyte concentration of the electrolytic cell from the set value.

[0100] K3 corresponds to the differential adjustment item. If the value of K3 is too large, the system will be very sensitive to interference, which will manifest as small interference factors (such as flow rate and temperature changes) causing large fluctuations in the electrolyte concentration of the electrolytic cell.

[0101] If K1, K2, and K3 are too small, the system reaction will be severely delayed, and the electrolyte concentration in the electrolytic cell will take a long time to change or may not change at all.

[0102] Assume that the standard concentration of the electrolyte in the electrolytic cell is S_C, and its value is obtained by the conductivity tester installed inside the electrolytic cell.

[0103] Assume that the current concentration of the electrolyte in the electrolytic cell is C_C, whose value is obtained by the conductivity tester installed inside the electrolytic cell.

[0104] Calculate the difference between the current concentration and the standard addition concentration D=C_C-S_C.

[0105] First, set K2 and K3 to zero, then: E=K1*D+0*A+0*B=K1*D;

[0106] Gradually increase K1 from zero until the system output shows equal-amplitude oscillation (critical stable state), record the K1 value at this time, define the K1 value at this time as Ku, and record the system oscillation period.

[0107] Only set K2 to zero, and multiply Ku by the Ziegler-Nichols coefficient 0.6, that is, K1=0.6*Ku. Within one oscillation cycle, obtain the concentration change rate value B, and obtain the difference D between the current concentration and the standard addition concentration, and substitute it into the formula:

[0108] E=K1*D+K3*B=0.6*Ku*D+K3*B.

[0109] Since K1, D, and B are known, by gradually increasing K3 from zero, the E value changes until the system stops oscillating. Note the K3 value at this time. Although the system is stable at this time, the output has a stable deviation △D.

[0110] Set a sampling period, obtain the values ​​of D, A, and B, and substitute them together with K1 and K3 into the formula: E=K1*D+K2*A+K3*B;

[0111] Increasing or decreasing the K2 value will change the E value, reducing the above-mentioned stable deviation △D and approaching zero. Note the K2 value at this time.

[0112] At this point, the system is stable and does not oscillate, the deviation is close to zero, and the adjustment coefficients K1, K2, and K3 are adjusted.

[0113] Step 4: concentration adjustment;

[0114] During the first sampling time △t1, obtain the integral value A1 of the change of the current electrolyte concentration C_C relative to the standard concentration S_C;

[0115] During the sampling time △t1, the value B1 of the change rate of the current electrolyte concentration C_C relative to the standard concentration S_C is obtained;

[0116] At the end of sampling time △t1, the difference D1 between the current electrolyte concentration C_C and the standard concentration S_C is obtained;

[0117] Substitute the values ​​of A, B, and D into the formula E = K1*D1+K2*A1+K3*B1;

[0118] Since the system adjustment coefficients K1, K2, and K3 are known, the conduction frequency E value of the pure water solenoid valve can be obtained;

[0119] After the pure water solenoid valve conduction frequency E value is executed, the concentration of the electrolytic mixed liquid in the premixed liquid storage tank will not change immediately due to the hysteresis of the system;

[0120] During the second sampling time △t2, the integral value A2 of the change of the current electrolyte concentration C_C relative to the standard concentration S_C is obtained;

[0121] During the sampling time △t2, the value B2 of the change rate of the current electrolyte concentration C_C relative to the standard concentration S_C is obtained;

[0122] At the end of sampling time △t2, the difference D2 between the current electrolyte concentration C_C and the standard concentration S_C is obtained;

[0123] Substitute the values ​​of A2, B2, and D2 into the formula E = K1*D2+K2*A2+K3*B2 to obtain the conduction frequency E value of the pure water solenoid valve;

[0124] This is done continuously for n times (△t1, △t2...△tn), and the value of the conduction frequency E of the pure water solenoid valve is constantly revised according to A, B, and D, so that the electrolyte concentration of the balanced electrolytic cell can be dynamically adjusted to keep it consistent with the electrolyte concentration of the electrolytic cell.

[0125] The electronic control module continuously compares the new concentration data with the standard concentration, and adjusts the conduction frequency and time of the pure water solenoid valve until the concentration reaches the target value.

[0126] When the concentration approaches the target value, the electronic control module automatically adjusts to gradually reduce the conduction frequency and time of the pure water solenoid valve to avoid excessive concentration adjustment.

[0127] The description of the present invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the form disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as are suited for specific applications.

Claims

1. A method for adjusting an automatic regulating system for the balance of electrolyte concentration for hydrogen production by electrolysis of water, characterized by: The regulating system includes an electrolyzer connected to a hydrogen gas-liquid separator and an oxygen liquid separator; The hydrogen-liquid separator, the oxygen-liquid separator and the electrolyzer are all connected to a premixed liquid storage tank, the premixed liquid storage tank contains premixed electrolyte, the premixed liquid storage tank is connected to a pure water storage tank, and a pure water solenoid valve is provided between the pure water storage tank and the premixed liquid storage tank; The adjustment method comprises the following steps: Step 1: The liquid level sensor in the electrolytic cell detects the liquid level in the electrolytic cell. The electronic control module replenishes the corresponding premixed electrolyte from the premixed liquid storage tank according to the electrolyte missing in the electrolytic cell. The premixed electrolyte is continuously replenished as the electrolyte in the electrolytic cell is consumed, so that the electrolyte in the electrolytic cell is always maintained at the same liquid level; Step 2: The conductivity tester in the electrolytic cell continuously detects the electrolyte concentration in the electrolytic cell, and adjusts the action of the pure water solenoid valve according to the electrolyte concentration. Based on the fact that the amount of pure water passing through the pure water solenoid valve within one conduction time is a fixed value, if the electrolyte concentration is higher than the standard concentration, the conduction frequency of the pure water solenoid valve is gradually increased to increase the amount of pure water inlet. If the electrolyte concentration is lower than the standard concentration, the conduction frequency of the pure water solenoid valve is gradually reduced to reduce the amount of pure water inlet. A rehydration solenoid valve and a rehydration pump are provided between the electrolytic cell and the premixed liquid storage tank; A conductivity tester is installed inside the electrolytic cell to obtain the concentration of the electrolyte in the electrolytic cell; A liquid level sensor is installed inside the electrolytic cell to obtain the liquid level of the electrolyte in the electrolytic cell; The electrolyte concentration balance automatic adjustment system further includes an electronic control module, which is connected to the pure water solenoid valve, the liquid replenishment solenoid valve, the liquid replenishment pump, the liquid level sensor and the conductivity tester; The step 2 specifically includes the following steps: Step 1: Get data; Step 1.1: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the integral value A of the concentration change of the current electrolyte concentration relative to the standard concentration within the k sampling time; Step 1.2: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the concentration change rate value B of the current electrolyte concentration relative to the standard concentration within the k sampling time; Step 1.3: The electronic control module detects the electrolyte concentration in the electrolytic cell using a conductivity tester, sets the sampling period to △t, and obtains the difference D between the current electrolyte concentration and the standard concentration at the end of the k sampling time; The integral value of the concentration change , j is the number of sampling cycles within the k sampling time, and D(j) is the difference between the electrolyte concentration and the standard concentration in the j-th sampling cycle; The step 2 specifically further includes the following steps: Step 2: Determine the adjustment plan; Introduce the proportional differential integral comprehensive regulation method to adjust the pure water solenoid valve: E=K1*D+K2*A+K3*B; in: E is the conduction frequency of the pure water solenoid valve; K1, K2, and K3 are system adjustment coefficients; K1*D is a proportional adjustment item, which proportionally adjusts the conduction time of the pure water solenoid valve according to the deviation between the current electrolyte concentration of the electrolytic cell and the standard concentration; K2*A is the integral adjustment item, which is used to eliminate the steady-state error of the system. It will integrate the concentration deviation. As time accumulates, the integral item will gradually increase, causing the conduction time of the pure water solenoid valve to gradually increase to ensure that the standard concentration can be reached in the end; K3*B is the differential adjustment item, which adjusts the conduction time of the pure water solenoid valve in advance according to the change rate of the concentration deviation. When the concentration changes too quickly, the differential link will make corresponding adjustments to the conduction time of the pure water solenoid valve to prevent excessive concentration adjustment and stabilize the adjustment process. Since the amount of pure water passing through the pure water solenoid valve within one conduction time is a fixed value, the pure water flow rate can be changed by changing the conduction frequency E of the pure water solenoid valve; by adjusting the size of the pure water flow rate, the mixing ratio of pure water in the premixed electrolyte can be changed, and the concentration of the premixed electrolyte mixture in the premixed liquid storage tank can be adjusted; As the E value increases, the proportion of pure water added increases and the concentration of the premixed electrolyte decreases; as the E value decreases, the proportion of pure water added decreases and the concentration of the premixed electrolyte increases.

2. The method for adjusting the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolysis of water according to claim 1, characterized in that: The step 2 specifically further includes the following steps: Step 3: System tuning, calculation of adjustment coefficient; Assume that the standard concentration of the electrolyte in the electrolytic cell is S_C, and its value is obtained by the conductivity tester installed inside the electrolytic cell; Assume that the current concentration of the electrolyte in the electrolytic cell is C_C, whose value is obtained by the conductivity meter installed inside the electrolytic cell; Calculate the difference between the current concentration and the standard addition concentration D=C_C-S_C; First, set K2 and K3 to zero, then: E=K1*D+0*A+0*B=K1*D; Gradually increase K1 from zero until the system output oscillates with equal amplitude. Note the K1 value at this time, define the K1 value at this time as Ku, and note the system oscillation period.

3. The method for adjusting the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolysis of water according to claim 2, characterized in that: The step 3 further comprises the following steps: Only set K2 to zero, and multiply Ku by the Ziegler-Nichols coefficient 0.6, that is, K1=0.6*Ku. Within one oscillation cycle, obtain the concentration change rate value B, and obtain the difference D between the current concentration and the standard addition concentration, and substitute it into the formula: E=K1*D+K3*B=0.6*Ku*D+K3*B; Since K1, D, and B are known, by gradually increasing K3 from zero, the E value changes until the system stops oscillating. Note the K3 value at this time. Although the system is stable at this time, the output has a stable deviation △D.

4. The method for adjusting the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolysis of water according to claim 3, characterized in that: The step 3 further comprises the following steps: Set a sampling period, obtain the values ​​of D, A, and B, and substitute them together with K1 and K3 into the formula: E=K1*D+K2*A+K3*B; Increase or decrease the K2 value, and the E value changes, so that the above-mentioned stable deviation △D decreases and approaches zero, and record the K2 value at this time; At this point, the system is stable and does not oscillate, the deviation is close to zero, and the adjustment coefficients K1, K2, and K3 are adjusted.

5. The method for adjusting the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolysis of water according to claim 4, characterized in that: The step 2 specifically further includes the following steps: Step 4: concentration adjustment; After the pure water solenoid valve conduction frequency E value is executed, the electrolyte concentration will not change immediately due to the hysteresis of the system; By continuously performing n sampling times and constantly revising the conduction frequency E value of the pure water solenoid valve according to A, B, and D, the electrolyte concentration of the balanced electrolytic cell can be dynamically adjusted to keep it consistent with the electrolyte concentration of the electrolytic cell; The electronic control module continuously compares the new concentration data with the standard concentration and adjusts the conduction of the pure water solenoid valve. Frequency and time until the concentration reaches the target value; When the concentration approaches the target value, the electronic control module automatically adjusts to gradually reduce the conduction frequency and time of the pure water solenoid valve to avoid excessive concentration adjustment.

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