Adjusting method of electrolyte concentration balance automatic adjusting system for water electrolysis hydrogen production

Abstract

The invention discloses an adjusting method of an electrolyte concentration balance automatic adjusting system for water electrolysis hydrogen production, and belongs to the technical field of electrolysis processes, the system comprises an electrolytic bath, an electrolyte is placed in the electrolytic bath, and the electrolytic bath is connected with a hydrogen-liquid separator and an oxygen-liquid separator; the hydrogen-liquid separator, the oxygen-liquid separator and the electrolytic bath are all connected with a premixed liquid storage tank, premixed electrolyte is stored in the premixed liquid storage tank, the premixed liquid storage tank is connected with a pure water storage tank, a pure water electromagnetic valve is arranged between the pure water storage tank and the premixed liquid storage tank, and the pure water is limited in flow through the pure water electromagnetic valve. The method has the following advantages that the concentration of the electrolyte in the electrolytic cell is monitored, when the concentration of the electrolyte is changed due to the change of technological parameters (temperature, pressure, liquid level and current density) in the electrolysis process, the addition of the premixed electrolyte with specific concentration is controlled through an intelligent algorithm, and pure water and electrolyte consumed by electrolysis are supplemented; and dynamically adjusting and balancing the electrolyte concentration of the electrolytic cell to keep the liquid level and the electrolyte concentration of the electrolytic cell constant.

Description

Technical Field

[0001] The present invention is a method for automatically adjusting the electrolyte concentration balance of an electrolytic water hydrogen production electrolyte concentration balance automatic adjustment system, belonging to the technical field of electrolysis processes. Background Art

[0002] During the electrolytic water hydrogen production process, direct current is passed through the electrolyte in the electrolytic cell, and water molecules undergo electrochemical reactions on the electrodes. Hydrogen and hydroxide ions are generated at the cathode, and the hydroxide ions migrate to the anode through the diaphragm. At the anode, the hydroxide ions lose electrons to generate oxygen; the main functions of the electrolyte during the electrolytic water hydrogen production process are to provide ion conduction, reduce power consumption, protect the electrodes, and extend the service life of the electrolytic cell.

[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] The electrolyte concentration is an important parameter in the electrolytic water hydrogen production process. During the electrolysis process, due to the adjustment of process parameters or the interference of accidental factors, the electrolyte concentration in the electrolytic cell is likely to fluctuate. If the fluctuation is not eliminated for a long time, it will cause harm. When the electrolyte concentration is too high, it will corrode the asbestos membrane, precipitate crystals, and block the liquid channels and gas channels, resulting in the abnormal operation of the electrolytic cell; when the electrolyte concentration is too low, it will increase power consumption, weaken the passivation of metals, reduce gas purity, and increase equipment corrosion.

[0005] During the electrolysis process, the electrolyte level must be kept constant. The electrolyte is a medium for ion conduction. Insufficient liquid level will cause part of the electrode to be exposed to the air, reducing the electrode surface area participating in the reaction and lowering the electrolysis efficiency. At the same time, changes in the electrolyte level will change the resistance between the electrodes, resulting in fluctuations in the electrolytic cell voltage. To maintain a constant current, the power supply needs to frequently adjust the output, which may increase energy consumption or affect the equipment life. Therefore, there are electrolyte recovery cycles and water replenishment devices during the electrolysis process. The water replenishment device adds water to the electrolytic cell to maintain a constant electrolytic cell level; after the hydrogen, oxygen, and electrolyte vapor generated by electrolysis are mixed, they enter the gas-liquid separator. The separated hydrogen and oxygen are collected and stored, and the high-concentration electrolyte generated after separation flows back to the electrolytic cell for recycling.

[0006] The prior art has the following disadvantages: The prior art cannot eliminate the influence of accidental interference factors on the control system, resulting in system oscillation or even deterioration. For example, voltage fluctuations reduce the current density of the electrolytic cell, lower the pressure of the electrolytic cell, slow down the flow rate of the electrolyte recovered by gas-liquid separation, reduce the amount of the high-concentration electrolyte in the reflux, lower the concentration of the electrolyte in the entire electrolytic cell, reduce the conductivity, slow down the electrolytic reaction of the electrolytic cell, further lower the pressure, and cause positive feedback deterioration of the electrolytic reaction, further lowering the concentration of the electrolyte in the electrolytic cell.

[0007] Due to the uncertain factors of gas-liquid separation reflux, the concentration of the electrolyte in the electrolytic cell fluctuates up and down, causing corrosion, blockage of the electrolytic equipment, and reduction of gas purity. The prior art only controls the makeup water volume to keep the liquid level of the electrolytic cell constant. In theory, electrolyzing water only consumes water and does not consume electrolytes. As long as water is replenished to keep the liquid level of the electrolytic cell, it is okay. In actual production, the hydrogen and oxygen generated 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 fluctuations and oscillations of the process parameters during the production process, the concentration and quantity of the refluxed electrolyte change. The instability of the quantity of the refluxed electrolyte causes the concentration of the electrolytic cell to fluctuate up and down.

[0008] The adjustment of production capacity causes the concentration of the electrolyte in the electrolytic cell to fluctuate up and down, resulting in corrosion, blockage of the electrolytic equipment, and reduction of gas purity. The prior art cannot dynamically adjust the electrolyte concentration. When the production capacity of electrolyzing water to produce hydrogen is adjusted, it is necessary to modify the process parameters to increase or decrease the power of the electrolytic cell. The adjustment of the process parameters breaks the electrolyte concentration balance and causes the electrolyte concentration to change. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide an automatic adjustment system and method for the electrolyte concentration balance of electrolyzing water to produce hydrogen to 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 electrolysis, the addition of premixed electrolyte with a specific concentration is controlled through an intelligent algorithm to supplement the pure water and electrolytes consumed by electrolysis, dynamically adjust and balance the electrolyte concentration in the electrolytic cell, and keep the liquid level and electrolyte concentration of the electrolytic cell constant.

[0010] To solve the above technical problems, the present invention adopts the following technical solutions: An automatic adjustment system for the electrolyte concentration balance of electrolyzing water to produce hydrogen includes an electrolytic cell with electrolyte placed inside, and the electrolytic cell is 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. The premixed liquid storage tank stores 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 pure water is limited in flow by the pure water solenoid valve; The electrolytic recovery liquid generated by the gas-liquid separation of the electrolytic cell flows into the premixing storage tank from the bottom of the hydrogen gas-liquid separator and the bottom of the oxygen gas-liquid separator respectively. Pure water dilutes the high-concentration electrolytic recovery liquid and mixes it to form a premixed electrolyte with a certain concentration, and then it flows back to the electrolytic cell. By controlling the flow rate of pure water, the concentration of the electrolyte can be dynamically adjusted.

[0011] Furthermore, a liquid supplement solenoid valve and a liquid supplement pump are provided between the electrolytic cell and the premixing 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, and the electronic control module is connected to the pure water solenoid valve, the liquid supplement solenoid valve, the liquid supplement pump, the liquid level sensor and the conductivity tester.

[0012] A method for adjusting an electrolyte concentration balance automatic adjustment system for electrolytic water hydrogen production includes the following steps: Step 1: The liquid level sensor in the electrolytic cell detects the liquid level of the electrolytic cell, and the electronic control module fills the corresponding premixed electrolyte from the premixing storage tank according to the lacking electrolyte in the electrolytic cell. The premixed electrolyte is continuously filled as the electrolyte in the electrolytic cell is consumed, so that the electrolyte in the electrolytic cell always remains at the same liquid level; Step 2: The conductivity tester in the electrolytic cell continuously detects the concentration of the electrolyte 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 inflow. If the electrolyte concentration is lower than the standard concentration, the conduction frequency of the pure water solenoid valve is gradually decreased to reduce the pure water inflow.

[0013] Furthermore, the specific steps of Step 2 include the following steps: Step 1: Obtain data; Step 1.1: The electronic control module detects the concentration of the electrolyte in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and obtains the integral fraction value A of the concentration change amount of the current electrolyte concentration relative to the standard concentration within the k sampling time; Step 1.2: The electronic control module detects the concentration of the electrolyte in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and obtains the numerical value B of the concentration change speed of the current electrolyte concentration relative to the standard concentration within the k sampling time; Step 1.3: The electronic control module detects the concentration of the electrolyte in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and obtains the difference D between the current electrolyte concentration and the standard concentration at the end of the k sampling time; Among them, the integral fraction value of the concentration change amount , where j is the number of sampling periods within k sampling times, and D(j) is the difference between the electrolyte concentration and the standard concentration in the j-th sampling period.

[0014] Further, the specific steps of the second step further include the following steps: Step 2: Determine the adjustment scheme; Introduce a proportional-integral-derivative comprehensive adjustment method to adjust the pure water solenoid valve: E = K1*D + K2*A + K3*B; Where: E is the conduction frequency of the pure water solenoid valve; K1, K2, and K3 are system adjustment coefficients; K1*D is the proportional adjustment term, which proportionally adjusts the conduction time of the pure water solenoid valve according to the deviation between the current electrolyte concentration in the electrolytic cell and the standard concentration; K2*A is the integral adjustment term, which is used to eliminate the steady-state error of the system. It integrates the concentration deviation. As time accumulates, the integral term will gradually increase, causing the conduction time of the pure water solenoid valve to gradually increase to ensure that the standard concentration can be finally achieved; K3*B is the derivative adjustment term, 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 fast, the derivative link will make corresponding adjustments to the conduction time of the pure water solenoid valve to prevent excessive concentration adjustment and play a role in stabilizing the adjustment process; Since the amount of pure water passing through within one conduction time of the pure water solenoid valve is a fixed value, changing the conduction frequency E of the pure water solenoid valve can change the pure water flow rate; 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 electrolytic mixture in the premixed storage tank can be adjusted; When the value of E increases, the proportion of pure water added increases, and the concentration of the premixed electrolyte decreases; when the value of E decreases, the proportion of pure water added decreases, and the concentration of the premixed electrolyte increases.

[0015] Further, the specific steps of the second step further include the following steps: Step 3: System tuning, calculate the 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, and its value is obtained by the conductivity tester installed inside the electrolytic cell; Calculate the difference D = C_C - S_C between the current concentration and the standard addition concentration; 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 record the system oscillation period.

[0016] Furthermore, the step 3 further comprises the following steps: Only set K2 to zero, multiply Ku by the Ziegler-Nichols coefficient 0.6, that is, K1=0.6*Ku, obtain the concentration change rate value B within one oscillation cycle, obtain the difference D between the current concentration and the standard added 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. The K3 value at this time is recorded. Although the system is stable at this time, a stable deviation △D appears in the output.

[0017] Furthermore, 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, 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 set.

[0018] Furthermore, the step 2 specifically 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 value of the conduction frequency E 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 frequency and time of the pure water solenoid valve 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.

[0019] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art: Monitor the concentration of the electrolyte inside the electrolytic cell. When the concentration of the electrolyte changes due to changes in process parameters (temperature, pressure, liquid level, current density) during the electrolysis process, control the addition of premixed electrolyte at a specific concentration through an intelligent algorithm to supplement the pure water and electrolyte consumed by electrolysis, dynamically adjust and balance the concentration of the electrolyte in the electrolytic cell, and keep the liquid level and electrolyte concentration in the electrolytic cell constant. Brief Description of the Drawings

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0021] Figure 1 It is a schematic structural diagram of the automatic adjustment system for the balance of the electrolyte concentration in the present invention; Among them, 1 - electrolytic cell, 2 - hydrogen-liquid separator, 3 - oxygen-liquid separator, 4 - deoxidizer, 5 - dryer, 6 - hydrogen storage tank, 7 - premixed liquid storage tank, 8 - pure water storage tank, 9 - liquid addition solenoid valve, 10 - liquid addition pump, 11 - pure water solenoid valve. Specific Embodiments

[0022] Example, as Figure 1 shown, an automatic adjustment system for the balance of the electrolyte concentration in hydrogen production by electrolyzing water includes an electrolytic cell 1 with electrolyte placed inside. The electrolytic cell 1 is connected to a hydrogen-liquid separator 2 and an oxygen-liquid separator 3. The hydrogen-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.

[0023] The hydrogen-liquid separator 2, the oxygen-liquid separator 3, and the electrolytic cell 1 are all connected to a premixed liquid storage tank 7 which stores premixed electrolyte. The premixed liquid storage tank 7 is connected to a pure water storage tank 8. There is a liquid addition solenoid valve 9 and a liquid addition pump 10 between the electrolytic cell 1 and the premixed liquid storage tank 7, and there is a pure water solenoid valve 11 between the pure water storage tank 8 and the premixed liquid storage tank 7. The pure water is limited in flow by the pure water solenoid valve 11 and flows into the premixed liquid storage tank 7 at a set flow rate.

[0024] An electric conductivity tester is installed inside the electrolytic cell 1 to obtain the concentration of the electrolyte in the electrolytic cell.

[0025] A liquid level sensor is installed inside the electrolytic cell 1 to obtain the liquid level of the electrolyte in the electrolytic cell.

[0026] The electrolytic recovery liquid generated by the gas-liquid separation of the electrolytic cell 1 flows into the premixing storage tank from the bottom of the hydrogen gas-liquid separator and the bottom of the oxygen gas-liquid separator respectively. Pure water dilutes the high-concentration electrolytic recovery liquid to form a premixed electrolytic solution with a certain concentration, and then it flows back to the electrolytic cell 1. By controlling the flow rate of pure water, the concentration of the electrolytic solution can be dynamically adjusted.

[0027] The electrolytic solution concentration balance automatic adjustment system further includes an electric control module, which is connected to a pure water solenoid valve, a liquid supplement solenoid valve, a liquid supplement pump, a liquid level sensor, and a conductivity tester.

[0028] 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 hydrogen and oxygen. For the above reasons, the pure water and electrolyte in the electrolytic cell gradually decrease, resulting in a decrease in the liquid level of the electrolytic cell and a change in concentration. By real-time monitoring the concentration of the electrolytic solution in the electrolytic cell, the electric control module continuously samples and calculates the change trend, standard deviation, and change speed of the electrolytic solution concentration. The electric control module performs coefficient weighting on these three variables, and converts the weighted result into the action parameters of the pure water solenoid valve. By adjusting the action parameters of the pure water solenoid valve, the proportion of pure water in the premixed electrolytic solution can be changed, thereby changing the concentration of the premixed electrolytic solution. By adding a premixed electrolytic solution with a suitable concentration to the electrolytic cell, the change in the concentration of the electrolytic solution in the electrolytic cell can be dynamically balanced.

[0029] A method for adjusting the balance of the electrolytic solution concentration in an electrolytic water hydrogen production system includes the following steps: Step 1: The liquid level sensor in the electrolytic cell detects the liquid level of the electrolytic cell, and the electric control module replenishes the corresponding premixed electrolytic solution from the premixing storage tank according to the lacking electrolytic solution in the electrolytic cell. The premixed electrolytic solution is continuously replenished as the electrolytic solution in the electrolytic cell is consumed, so that the electrolytic solution in the electrolytic cell always remains at the same liquid level.

[0030] Step 2: The conductivity tester in the electrolytic cell continuously detects the concentration of the electrolytic solution in the electrolytic cell, and adjusts the action of the pure water solenoid valve according to the concentration of the electrolytic solution. If the concentration of the electrolytic solution is higher than the standard concentration, gradually increase the conduction frequency of the pure water solenoid valve to increase the inflow of pure water. If the concentration of the electrolytic solution is lower than the standard concentration, gradually decrease the conduction frequency of the pure water solenoid valve to reduce the inflow of pure water. The specific adjustment steps are as follows: Step 1: Obtain data.

[0031] Step 1.1: The electric control module detects the concentration of the electrolytic solution in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and obtains the integral fraction value A of the concentration change amount of the current electrolytic solution relative to the standard concentration within the k sampling time. Step 1.2: The electric control module detects the concentration of the electrolytic solution in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and obtains the numerical value B of the concentration change speed of the current electrolytic solution relative to the standard concentration within the k sampling time. Step 1.3: The electronic control module detects the concentration of the electrolyte in the electrolytic cell through a conductivity tester, sets the sampling period as △t, and at the end of the k sampling time, obtains the difference D between the current electrolyte concentration and the standard concentration. where the integral value of the concentration change , j is the number of sampling periods within the k sampling time, D(j) is the difference between the electrolyte concentration and the standard concentration in the j-th sampling period. For example, assuming the sampling period △t is 1 minute, and the concentration deviations within k = 5 minutes are 3%, 4%, 4.5%, 4.8%, and 5% respectively, then A = (3% + 4% + 4.5% + 4.8% + 5%) × 1 = 21.3%.

[0032] The numerical value of the concentration change rate , D(k - 1) is the difference between the current electrolyte concentration and the standard concentration at the end of the (k - 1) sampling time.

[0033] Step 1.1, Step 1.2, and Step 1.3 are carried out synchronously within a unit sampling period.

[0034] Step 2: Determine the adjustment scheme; The difficulty in precisely controlling a lag system is that after changing the input quantity, the output quantity will not change immediately but requires a certain amount of time; this poses a problem in controlling the magnitude of the input quantity; If the input quantity changes too much, the output quantity will overshoot and oscillate. If the input quantity changes too little, the output quantity will be sluggish. When the system finally stabilizes, it is found that there is still a large error; To solve the above problems, a proportional-integral-derivative comprehensive adjustment method is introduced to adjust the pure water solenoid valve: E = K1 * D + K2 * A + K3 * B; where: E is the conduction frequency of the pure water solenoid valve; K1, K2, and K3 are system adjustment coefficients.

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

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

[0037] K3*B is the differential regulation term, 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 fast, the differential link will make corresponding adjustments to the conduction time of the pure water solenoid valve to prevent excessive concentration regulation and play a role in stabilizing the regulation process.

[0038] Since the amount of pure water passing through in one conduction time of the pure water solenoid valve is a fixed value, changing the conduction frequency E of the pure water solenoid valve can change the pure water flow rate; 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 electrolytic mixed solution in the premixed storage tank can be adjusted.

[0039] When the value of E increases, the proportion of the pure water addition amount increases, and the concentration of the premixed electrolyte decreases; when the value of E decreases, the proportion of the pure water addition amount decreases, and the concentration of the premixed electrolyte increases.

[0040] Step 3: System tuning, calculate the regulation coefficients; The numerical values of the regulation coefficients K1, K2, and K3 determine the performance of the system regulation.

[0041] K1 corresponds to the proportional regulation term. If the value of K1 is too large, the system will oscillate violently and cannot be stable, manifested as the concentration of the electrolyte in the electrolytic cell fluctuating greatly.

[0042] K2 corresponds to the integral regulation term. If the value of K2 is too large, the system will have a steady-state error, manifested as the concentration of the electrolyte in the electrolytic cell stably deviating from the set value.

[0043] K3 corresponds to the differential regulation term. If the value of K3 is too large, the system will be very sensitive to interference, manifested as a large fluctuation in the concentration of the electrolyte in the electrolytic cell caused by minor interference factors (such as flow rate and temperature changes).

[0044] If K1, K2, and K3 are too small, the system response will be severely lagged, and it will take a long time for the concentration of the electrolyte in the electrolytic cell to change or even not change.

[0045] Let the standard concentration of the electrolyte in the electrolytic cell be S_C, and its value is obtained by the conductivity tester installed inside the electrolytic cell.

[0046] Let the current concentration of the electrolyte in the electrolytic cell be C_C, and its value is obtained by the conductivity tester installed inside the electrolytic cell.

[0047] Calculate the difference D = C_C - S_C between the current concentration and the standard addition concentration.

[0048] 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 shows equal-amplitude oscillation (critical stable state), record the value of K1 at this time, define the K1 value at this time as Ku, and record the system oscillation period.

[0049] Only set K2 to zero, multiply Ku by the Ziegler-Nichols coefficient 0.6, that is, K1=0.6*Ku, obtain the concentration change rate value B within one oscillation cycle, obtain the difference D between the current concentration and the standard added concentration, and substitute it into the formula: 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, and the K3 value at this time is recorded. At this time, although the system is stable, the output has a stable deviation △D; 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; Increasing or decreasing the K2 value will change the E value, so that the above-mentioned stable deviation △D will decrease and approach zero. Record the K2 value at this time.

[0051] 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 set.

[0052] Step 4: concentration adjustment; In 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; During the sampling time △t1, obtain the value B1 of the change rate of the current electrolyte concentration C_C relative to the standard concentration S_C; At the end of the sampling time △t1, the difference D1 between the current electrolyte concentration C_C and the standard concentration S_C is obtained; Substitute the values ​​of A, B, and D into the formula E = K1*D1+K2*A1+K3*B1; Since the system adjustment coefficients K1, K2, and K3 are known, the value of the conduction frequency E of the pure water solenoid valve can be obtained; After the pure water solenoid valve conduction frequency E value is executed, the concentration of the electrolyte mixed liquid in the premixed liquid storage tank will not change immediately due to the hysteresis of the system; In the second sampling time △t2, obtain the integral value A2 of the change of the current electrolyte concentration C_C relative to the standard concentration S_C; During the sampling time △t2, obtain the value B2 of the change rate of the current electrolyte concentration C_C relative to the standard concentration S_C; At the end of the sampling time △t2, the difference D2 between the current electrolyte concentration C_C and the standard concentration S_C is obtained; Substitute the values of A2, B2, and D2 into the formula E = K1*D2 + K2*A2 + K3*B2 to obtain the value of the conduction frequency E of the pure water solenoid valve; Perform this continuously for n time intervals (△t1, △t2... △tn), and continuously revise the conduction frequency E value of the pure water solenoid valve according to A, B, and D, then the electrolyte concentration in the electrolytic cell can be dynamically adjusted to be consistent with the electrolyte concentration in the electrolytic cell.

[0053] 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.

[0054] 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.

[0055] The description of the present invention is given for purposes of illustration and description, and is not intended to be exhaustive or to limit the invention to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are chosen and described in order to best explain the principles of the invention and its practical application, and to enable those of ordinary skill in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

Claims

1. Adjusting method for electrolyte concentration balance automatic adjustment system in hydrogen production by electrolyzing water, characterized in that: The described adjustment system includes an electrolytic cell, which is connected to a hydrogen - liquid separator and an oxygen - liquid separator; The hydrogen - liquid separator, oxygen - liquid separator, and electrolytic cell are all connected to a premixed liquid storage tank. The premixed liquid storage tank stores 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 described adjustment method includes the following steps: 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 lacking 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 always remains at the same liquid level; Step 2: The conductivity tester in the electrolytic cell continuously detects the concentration of the electrolyte 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 within one conduction time of the pure - water solenoid valve 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 pure - water inflow. If the electrolyte concentration is lower than the standard concentration, the conduction frequency of the pure - water solenoid valve is gradually decreased to reduce the pure - water inflow.

2. The adjustment method of the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolyzing water according to claim 1, characterized in that: A liquid - supplement solenoid valve and a liquid - supplement pump are provided between the electrolytic cell and the premixed liquid storage tank; A conductivity tester is installed inside the electrolytic cell, which can obtain the concentration of the electrolyte in the electrolytic cell; A liquid - level sensor is installed inside the electrolytic cell, which can obtain the liquid level of the electrolyte in the electrolytic cell; The automatic adjustment system for electrolyte concentration balance further includes an electronic control module, which is connected to the pure - water solenoid valve, liquid - supplement solenoid valve, liquid - supplement pump, liquid - level sensor, and conductivity tester.

3. The adjustment method of the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolyzing water according to claim 1, characterized in that: The specific content of Step 2 includes the following steps: Step 1: Obtain data; Step 1.1: The electronic control module detects the concentration of the electrolyte in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and within the k - th sampling time, obtains the integral value A of the concentration change amount of the current electrolyte concentration relative to the standard concentration; Step 1.2: The electronic control module detects the concentration of the electrolyte in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and within the k - th sampling time, obtains the numerical value B of the concentration change speed of the current electrolyte concentration relative to the standard concentration; Step 1.3: The electronic control module detects the concentration of the electrolyte in the electrolytic cell through the conductivity tester, sets the sampling period as △t, and at the end of the k - th sampling time, obtains the difference D between the current electrolyte concentration and the standard concentration; where the integral value of the concentration change , j is the number of sampling periods within the k sampling time, and D(j) is the difference between the electrolyte concentration and the standard concentration in the j-th sampling period.

4. The adjustment method of the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolyzing water according to claim 1, characterized in that: The specific content of Step 2 further includes the following steps: Step 2: Determine the adjustment plan; Introduce the use of a proportional - integral - derivative comprehensive adjustment method to adjust the pure - water solenoid valve: E = K1*D+K2*A+K3*B; Where: E is the conduction frequency of the pure - water solenoid valve; K1, K2, and K3 are system adjustment coefficients; K1*D is the proportional adjustment term, which proportionally adjusts the conduction time of the pure - water solenoid valve according to the deviation between the current electrolyte concentration in the electrolytic cell and the standard concentration; K2*A is the integral adjustment term, which is used to eliminate the steady - state error of the system. It integrates the concentration deviation. As time accumulates, the integral term will gradually increase, causing the conduction time of the pure - water solenoid valve to gradually increase to ensure that the standard concentration can be finally achieved; K3*B is the differential adjustment term, 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 fast, the differential link will make corresponding adjustments to the conduction time of the pure water solenoid valve to prevent excessive concentration adjustment and play a role in stabilizing the adjustment process; Since the amount of pure water passing through within one conduction time of the pure water solenoid valve is a fixed value, changing the conduction frequency E of the pure water solenoid valve can change the pure water flow rate; 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 electrolytic mixture in the premixed storage tank can be adjusted; When the value of E increases, the proportion of pure water added increases and the concentration of the premixed electrolyte decreases; when the value of E decreases, the proportion of pure water added decreases and the concentration of the premixed electrolyte increases.

5. The adjustment method of the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolyzing water according to claim 4, characterized in that: The specific steps of step two further include the following steps: Step 3: System tuning, calculating the adjustment coefficients; Let the standard concentration of the electrolyte in the electrolytic cell be S_C, and its value is obtained by the conductivity tester installed inside the electrolytic cell; Let the current concentration of the electrolyte in the electrolytic cell be C_C, and its value is obtained by the conductivity tester installed inside the electrolytic cell; Calculate the difference D = C_C - S_C between the current concentration and the standard addition concentration; 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 shows equal-amplitude oscillation, record the value of K1 at this time, define the K1 value at this time as Ku, and record the system oscillation period.

6. The adjustment method of the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolyzing water according to claim 5, characterized in that: Step 3 further includes the following steps: Only set K2 to zero, multiply Ku by the Ziegler-Nichols coefficient 0.6, that is, K1 = 0.6*Ku. Within one oscillation period, obtain the value B of the concentration change rate, 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, gradually increase K3 from zero, the value of E changes until the system stops oscillating, record the value of K3 at this time. Although the system is stable at this time, there is a stable deviation △D in the output.

7. The adjustment method of the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolyzing water according to claim 6, characterized in that: Step 3 further includes the following steps: Set a sampling period, obtain the values of D, A, and B, together with K1 and K3, and substitute them into the formula: E = K1*D + K2*A + K3*B; Increase or decrease the value of K2, the value of E changes, so that the above stable deviation △D decreases and approaches zero, and record the value of K2 at this time; At this point, the system is stable and does not oscillate, the deviation approaches zero, and the adjustment coefficients K1, K2, and K3 are tuned.

8. The adjustment method of the electrolyte concentration balance automatic adjustment system for hydrogen production by electrolyzing water according to claim 4, characterized in that: The specific steps of step two further include the following steps: Step 4: Concentration adjustment; After the value of the conduction frequency E of the pure water solenoid valve is executed, due to the hysteresis of the system, the electrolyte concentration will not change immediately; Continuously perform n sampling times, and continuously revise the value of the conduction frequency E of the pure water solenoid valve according to A, B, and D, so as to dynamically adjust and balance the electrolyte concentration in the electrolytic cell to make it consistent with the electrolyte concentration in the electrolytic cell; 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; 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.

Images