Water electrolysis hydrogen production device based on pneumatic control back pressure valve and control method

Abstract

The invention provides a water electrolysis hydrogen production device based on a pneumatic control back pressure valve and a control method, and can solve the problems that the system pressure is out of control and the hydrogen and oxygen side liquid level is unbalanced due to dynamic fluctuation of hydrogen production / oxygen production of water electrolysis hydrogen production equipment under the new energy power generation coupling working condition. Comprising an electrolytic bath, a gas-liquid processor and a control cabinet, the electrolytic bath is used for providing electrolyte for the gas-liquid processor, and the control cabinet is used for controlling the system pressure of the gas-liquid processor to be stable. The amount of oxygen discharged by the oxygen side separator is controlled only through the oxygen side pneumatic control back pressure valve, and then the system pressure is controlled to reach the set pressure target; the amount of hydrogen discharged by the hydrogen side separator is adjusted through the gas control back pressure valve on the hydrogen side, so that the hydrogen pressure in the hydrogen side separator follows the gas pressure in the oxygen side separator all the time, and the liquid level balance is controlled.

Description

Technical Field

[0001] This invention belongs to the field of process control technology for water electrolysis hydrogen production equipment, specifically relating to a method for pressure regulation and hydrogen-oxygen side liquid level balance control of a water electrolysis hydrogen production equipment system based on a gas-controlled back pressure valve. It is particularly suitable for water electrolysis hydrogen production scenarios coupled with new energy power generation systems and can adapt to the intermittent, random, and fluctuating operating conditions of new energy power generation. Background Technology

[0002] With the large-scale development of new energy power generation, the demand for "curtailed electricity" utilization has driven water electrolysis hydrogen production technology to become an important path for new energy storage. By using new energy power to drive electrolyzers to produce hydrogen, the cost of hydrogen production electricity can be significantly reduced. However, the output power of new energy power generation has inherent fluctuations, intermittency, and randomness, causing the hydrogen and oxygen production of the electrolyzer to change dynamically with the power generation. This leads to system pressure fluctuations and imbalances in the hydrogen and oxygen levels within the gas-liquid separation and treatment device. If not properly controlled, this can easily result in substandard hydrogen purity or even safety risks due to hydrogen-oxygen cross-contamination. Therefore, an efficient and reliable pressure-level coordinated control scheme is needed.

[0003] Currently, pressure-level control in isobaric water electrolysis hydrogen production equipment mainly relies on two types of valves, but both have significant drawbacks:

[0004] Solenoid valve control scheme: High-frequency on / off regulation of hydrogen / oxygen flow to match pressure and level requirements. On the one hand, high-frequency operation easily causes valve seat wear and sealing performance degradation, significantly shortening valve lifespan and increasing equipment maintenance costs and downtime risks; on the other hand, the discrete regulation characteristics of solenoid valves cannot achieve smooth flow transitions, easily causing system pressure fluctuations and hydrogen / oxygen level deviations, directly leading to fluctuations in hydrogen purity and failing to meet the requirements of high-precision hydrogen production.

[0005] The diaphragm control valve solution, while achieving smooth flow control through continuous opening adjustment from 0-100%, has a narrow flow capacity (CV) range, making it difficult to cover the wide variations in electrolyzer gas production under new energy operating conditions. When gas production is in the low-load range, the diaphragm control valve opening is extremely small, easily leading to insufficient adjustment accuracy due to valve stem jamming; when gas production is in the high-load range, the valve's flow capacity is limited, easily causing system pressure to rise and triggering overpressure interlock shutdown.

[0006] Improved Dual-Thin-Film Control Valve Solution: Some equipment adopts a dual-thin-film control valve with "large CV value + small CV value" to cover a wide flow range. However, this solution has three major drawbacks: First, sudden flow changes are prone to occur during valve switching, causing a sudden rise / fall in system pressure; second, the dual-valve structure increases equipment complexity (additional valves, switching valve groups, and control logic), increasing installation and maintenance costs and potential failure points; third, the switching logic has a lag, which cannot match the rapid fluctuations of new energy power generation, and still cannot achieve stable control under all operating conditions.

[0007] In summary, existing control schemes, due to limitations in valve lifespan, adjustment accuracy, and adaptability to operating conditions, cannot meet the stable operation requirements of water electrolysis hydrogen production equipment in new energy coupling scenarios. There is an urgent need for a control scheme that combines a wide CV value range, continuous adjustment capability, and high reliability. Summary of the Invention

[0008] In view of this, the present invention proposes a water electrolysis hydrogen production device and control method based on a gas-controlled back pressure valve, which can solve the problems of system pressure runaway and hydrogen-oxygen side liquid level imbalance caused by dynamic fluctuations in hydrogen / oxygen production in water electrolysis hydrogen production equipment under new energy power generation coupling conditions. The specific technical solution is as follows:

[0009] A water electrolysis hydrogen production device based on a gas-controlled back pressure valve includes: an electrolyzer, a gas-liquid processor, and a control cabinet. The electrolyzer is used to supply electrolyte to the gas-liquid processor, and the control cabinet is used to control the system pressure stability of the gas-liquid processor.

[0010] Furthermore, the gas-liquid processor includes a circulating pump, a hydrogen-side separator, an oxygen-side separator, a hydrogen-side gas-controlled back pressure valve, an oxygen-side gas-controlled back pressure valve, a hydrogen-side differential pressure transmitter, an oxygen-side differential pressure transmitter, and an oxygen-side pressure transmitter. A connecting pipe is provided between the hydrogen and oxygen-side separators, and the circulating pump is placed between the electrolytic cell and the connecting pipe. The hydrogen-side gas-controlled back pressure valve is placed at the top of the hydrogen-side separator to control the liquid level in the hydrogen-side separator. The hydrogen-side differential pressure transmitter is placed in the hydrogen-side separator to measure the liquid level in the hydrogen-side separator. The oxygen-side gas-controlled back pressure valve is placed at the top of the oxygen-side separator to control the gas pressure in the oxygen-side separator, i.e., the system pressure. The oxygen-side differential pressure transmitter is placed in the oxygen-side separator to measure the liquid level in the oxygen-side separator. The oxygen-side pressure transmitter is placed in the oxygen-side separator to measure the system pressure. The control cabinet is used to output control signals for the hydrogen-side gas-controlled back pressure valve and the oxygen-side gas-controlled back pressure valve.

[0011] Furthermore, the control cabinet collects the output signals of the hydrogen-side differential pressure transmitter, the oxygen-side differential pressure transmitter, the oxygen-side pressure transmitter, and the electrolysis current of the electrolyzer in real time.

[0012] Furthermore, an electrical converter is installed to convert the control signals sent from the control cabinet into pneumatic signals, thereby controlling the hydrogen and oxygen side pneumatic back pressure valves.

[0013] Furthermore, the hydrogen and oxygen side gas-controlled back pressure valve has both automatic and manual control modes.

[0014] A water electrolysis hydrogen production control method based on a gas-controlled back pressure valve, specifically, based on the aforementioned device, controls the amount of oxygen discharged from the oxygen-side separator solely through the oxygen-side gas-controlled back pressure valve, thereby controlling the system pressure to reach the set pressure target; and adjusts the amount of hydrogen discharged from the hydrogen-side separator through the hydrogen-side gas-controlled back pressure valve, so that the hydrogen pressure in the hydrogen-side separator always follows the gas pressure in the oxygen-side separator, thereby controlling the liquid level balance.

[0015] Furthermore, the control methods include traditional PID control algorithms, fuzzy PID control algorithms, and model prediction-based control algorithms. The model prediction-based control algorithm also needs to collect real-time parameters of the electrolytic cell current, calculate the gas production rate using the formula between current and gas production rate, and open or close the back pressure valve of the gas vent in advance when the gas production rate suddenly increases or decreases, thereby achieving proactive control.

[0016] By implementing this invention, the following beneficial effects can be achieved:

[0017] 1. Stable control of system pressure: Avoid system overpressure chain shutdown caused by pressure fluctuations and adapt to wide range of gas production changes;

[0018] 2. Achieve precise balance of hydrogen and oxygen levels: Eliminate the safety hazard of hydrogen and oxygen cross-contamination caused by level imbalance;

[0019] 3. Ensure stable hydrogen purity: Through pressure-liquid level coordinated control, meet the requirements of industrial-grade high-purity hydrogen;

[0020] 4. Improve the reliability and economy of the control scheme: The pneumatic back pressure valve (with 0-100% continuous adjustable characteristics and wide CV value range) is adopted to avoid the high-frequency wear problem of solenoid valve and the insufficient adaptability of diaphragm regulating valve. At the same time, the system structure is simplified, maintenance costs and failure risks are reduced, and the long-term stable operation of water electrolysis hydrogen production equipment in new energy coupling scenarios is finally achieved. Attached Figure Description

[0021] Figure 1 Structural principle diagram of the device described in this invention;

[0022] Figure 2 The control flowchart of the method described in this invention. Detailed Implementation

[0023] The present invention achieves the above objectives through the following technical solutions:

[0024] This invention is based on Figure 1The system shown includes an electrolyzer, a gas-liquid processor, and a control cabinet. The gas-liquid processor includes a circulating pump, a hydrogen-side separator, an oxygen-side separator, a hydrogen-side gas-controlled back pressure valve LV1001, an oxygen-side gas-controlled back pressure valve PV1001, a hydrogen-side differential pressure transmitter LT1003, an oxygen-side differential pressure transmitter LT1001, and an oxygen-side pressure transmitter PT1001.

[0025] The specific work process is as follows:

[0026] S1. The circulating pump starts working, and the electrolytic cell is powered on;

[0027] S2, hydrogen and alkaline solution are mixed and flow out of the electrolyzer and enter the hydrogen-side separator;

[0028] S3, oxygen and alkaline solution are mixed and flow out of the electrolytic cell and enter the oxygen-side separator;

[0029] S4. Hydrogen and oxygen are separated in the hydrogen-oxygen side separator. The gas flows upward from the outlet, while the liquid remains in the separator.

[0030] S5, the control cabinet collects signals from hydrogen-side differential pressure transmitter LT1003, oxygen-side differential pressure transmitter LT1001, oxygen-side pressure transmitter PT1001, and electrolytic cell current IT1001 in real time.

[0031] S6. When the valve control mode is set to manual, the valve opening degree can be directly input to control the opening size of the valve.

[0032] S7. When the valve control mode is set to automatic mode, the control cabinet collects signals from the hydrogen-side differential pressure transmitter LT1003, the oxygen-side differential pressure transmitter LT1001, the oxygen-side pressure transmitter PT1001, and the electrolysis current IT1001 of the electrolyzer in real time. Through the corresponding automatic control algorithm, it controls the opening degree of the hydrogen-side gas-controlled back pressure valve LV1001 and the oxygen-side gas-controlled back pressure valve PV1001. Through one of the three control algorithms, the pressure and liquid level of the hydrogen production unit are stably controlled.

[0033] The technical solution of the present invention is further described below:

[0034] After the device is started up, the electrolyte is driven by a circulation pump to circulate between the gas-liquid processor and the electrolytic cell. When direct current is applied to the electrolytic cell, hydrogen and oxygen are produced. The hydrogen and alkali solution mix and flow into the hydrogen separator, while the oxygen and alkali solution mix and flow into the oxygen separator. The gas flows upward by gravity, while the liquid remains in the separator. A connecting pipe is installed between the hydrogen and oxygen side separators, allowing the alkali solutions from the two separators to mix.

[0035] Because the hydrogen production is twice that of oxygen, the oxygen-side pressure rises more slowly than the hydrogen-side pressure during pressurized operation. Since the separators on both sides are connected by a connecting pipe at the bottom, the pressures on both sides remain consistent and are collectively referred to as the system pressure. If the hydrogen-side pressure is high, the hydrogen level will drop, and the oxygen level will rise. Therefore, the hydrogen-side pneumatic back pressure valve LV1001 needs to be opened wider to release hydrogen and balance the levels. When the hydrogen-side pressure is lower than the oxygen-side pressure, the hydrogen-side level will be higher. In this case, the hydrogen-side valve should be closed slightly to allow the hydrogen-side pressure to rise and balance the levels. The oxygen-side pneumatic back pressure valve controls the release of oxygen to control the system pressure and achieve the set pressure target. The hydrogen-side pneumatic back pressure valve regulates the hydrogen-side pressure to always follow the oxygen-side pressure, thus controlling the level balance. Therefore, the hydrogen-side back pressure valve controls the liquid level, while the oxygen-side back pressure valve controls the system pressure.

[0036] The control cabinet collects signals from the hydrogen-side differential pressure transmitter LT1003, the oxygen-side differential pressure transmitter LT1001, the oxygen-side pressure transmitter PT1001, and the electrolysis current IT1001 of the electrolyzer in real time. Through corresponding automatic control algorithms, it controls the opening degree of the hydrogen-side gas-controlled back pressure valve LV1001 and the oxygen-side gas-controlled back pressure valve PV1001 to achieve stable control of the pressure and liquid level of the hydrogen production unit.

[0037] The hydrogen / oxygen side pneumatic back pressure valve of this invention can be controlled automatically and manually. In manual control, the desired valve opening degree can be directly output to control the valve's opening size. In automatic control mode, the opening degree of the hydrogen / oxygen side pneumatic back pressure valve is calculated using a corresponding pressure and level automatic control algorithm, achieving automatic control of pressure and level. The control flowchart is shown below. Figure 2 As shown. The three automatic control algorithms are as follows:

[0038] The first type is the traditional PID control algorithm. By setting the target system pressure value, a proportional-integral-derivative control algorithm is used to send a control signal to the electrical converter, which then controls the two pneumatic back pressure valves to achieve the control target.

[0039] The second control algorithm uses a fuzzy PID control algorithm. Based on the deviation of the controlled variable and the rate of change of the deviation, a fuzzy control table is formulated to achieve better control results.

[0040] The third control algorithm is a model prediction-based control algorithm. In addition to the above algorithms, this control algorithm also needs to collect real-time parameters of the electrolytic cell current. The gas production is calculated by using the formula between current and gas production. When the gas production suddenly increases or decreases, the back pressure valve of the gas vent is opened or closed in advance to achieve proactive control and provide stability of the controlled quantity.

[0041] Hydrogen production = Current × Number of chambers / 2390

[0042] The aforementioned electrical converter can convert the electrical control signals sent from the control cabinet into pneumatic signals, thereby controlling the pneumatic back pressure valve.

[0043] Based on existing pressure and level control schemes, this system is adapted to the operating mode of water electrolysis hydrogen production equipment in new energy power generation scenarios. The original control scheme addresses issues such as poor system pressure and hydrogen / oxygen level control, leading to poor hydrogen purity, system overpressure-induced shutdowns, and even safety hazards caused by excessive level deviations leading to hydrogen-oxygen cross-contamination.

Claims

1. A water electrolysis hydrogen production device based on a gas-controlled back pressure valve, characterized in that... include: An electrolytic cell, a gas-liquid processor, and a control cabinet are included. The electrolytic cell is used to supply electrolyte to the gas-liquid processor, and the control cabinet is used to control the system pressure stability of the gas-liquid processor.

2. The water electrolysis hydrogen production device based on a gas-controlled back pressure valve according to claim 1, characterized in that: The gas-liquid processor includes a circulating pump, a hydrogen-side separator, an oxygen-side separator, a hydrogen-side gas-controlled back pressure valve, an oxygen-side gas-controlled back pressure valve, a hydrogen-side differential pressure transmitter, an oxygen-side differential pressure transmitter, and an oxygen-side pressure transmitter. A connecting pipe is provided between the hydrogen and oxygen-side separators, and the circulating pump is placed between the electrolyzer and the connecting pipe. The hydrogen-side gas-controlled back pressure valve is located at the top of the hydrogen-side separator and is used to control the liquid level in the hydrogen-side separator. The hydrogen-side differential pressure transmitter is placed in the hydrogen-side separator to measure the liquid level inside the separator; the oxygen-side gas-controlled back pressure valve is placed at the top of the oxygen-side separator to control the gas pressure inside the separator, i.e., the system pressure; the oxygen-side differential pressure transmitter is placed in the oxygen-side separator to measure the liquid level inside; and the oxygen-side pressure transmitter is placed in the oxygen-side separator to measure the system pressure. The control cabinet is used to output control signals for the hydrogen-side gas-controlled back pressure valve and the oxygen-side gas-controlled back pressure valve.

3. The water electrolysis hydrogen production device based on a gas-controlled back pressure valve according to claim 1, characterized in that: The control cabinet collects the output signals of the hydrogen-side differential pressure transmitter, the oxygen-side differential pressure transmitter, the oxygen-side pressure transmitter, and the electrolysis current of the electrolyzer in real time.

4. A water electrolysis hydrogen production device based on a gas-controlled back pressure valve according to claim 1, characterized in that: An electrical converter is also installed to convert the control signals sent from the control cabinet into pneumatic signals, which in turn control the gas-controlled back pressure valves on the hydrogen and oxygen sides.

5. The apparatus according to any one of claims 1-4, characterized in that: The hydrogen and oxygen side gas-controlled back pressure valve has two control modes: automatic and manual.

6. A method for controlling hydrogen production by water electrolysis based on a gas-controlled back pressure valve, based on the apparatus described in claim 5, characterized in that: The amount of oxygen discharged from the oxygen-side separator is controlled by the oxygen-side gas-controlled back pressure valve, thereby controlling the system pressure to reach the set pressure target; the amount of hydrogen discharged from the hydrogen-side separator is adjusted by the hydrogen-side gas-controlled back pressure valve, so that the hydrogen pressure in the hydrogen-side separator always follows the gas pressure in the oxygen-side separator, thereby controlling the liquid level balance.

7. The control method according to claim 6, characterized in that: The control methods include traditional PID control algorithm, fuzzy control PID algorithm, and model prediction-based control algorithm. The model prediction-based control algorithm also needs to collect real-time parameters of the electrolytic cell current, calculate the gas production rate using the formula between current and gas production rate, and open or close the back pressure valve of the gas vent in advance when the gas production rate suddenly increases or decreases, so as to achieve proactive control.

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