Pressure three-out-of-center adjusting loop of water electrolysis hydrogen production system

Abstract

The utility model discloses a pressure three-in-one regulating loop of a water electrolysis hydrogen production system. The pressure three-in-one regulating loop comprises an electrolytic bath, an oxygen separator, an oxygen washer, an oxygen side gas-water separator, a pressure regulating valve and an emptying pipeline which are connected in sequence, the oxygen separator is connected with a liquid level transmitter, a first pressure transmitter, a second pressure transmitter and a third pressure transmitter, the first pressure transmitter, the second pressure transmitter and the third pressure transmitter are all connected with the control system, and the control system is connected with the pressure regulating valve. According to the scheme, the water electrolysis hydrogen production system adopts a'three-out-of-one 'regulating loop, so that system overpressure caused by a fault of single sensor equipment can be reduced, three signals can be subjected to mutual deviation inspection, a maintainer can quickly position a fault point, the system has higher reliability, and the maintenance cost is reduced. Therefore, the safe and stable operation of the water electrolysis hydrogen production system is ensured, and the stability of hydrogen quality is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of water electrolysis hydrogen production, and specifically relates to a pressure three-centering regulating loop of a water electrolysis hydrogen production system. Background Art

[0002] Installing a water electrolysis hydrogen production unit in renewable energy hydrogen production projects primarily based on wind and solar power can reduce wind and solar power curtailment rates, allowing hydrogen to participate in peak load regulation as an energy storage medium. However, the volatility and randomness of renewable energy can cause constant fluctuations in the hydrogen production system load, leading to sudden changes in system pressure, ultimately affecting hydrogen production and quality. For electrolyzers, system pressure should not be too high or too low. Excessive pressure can damage equipment and pipelines, resulting in safety incidents, while excessively low pressure can reduce system efficiency and increase energy consumption. In existing water electrolysis hydrogen production systems, because the pressure on the oxygen side is more stable during the water electrolysis process, a pressure regulation control loop is installed on the oxygen side. The pressure of the oxygen-side gas-liquid separator is selected as the system pressure measurement point, and a regulating valve is installed on the oxygen outlet pipeline. A single-seat diaphragm regulating valve is used as the regulating valve, and the control strategy adopts a single closed-loop fixed-value regulation system using PID regulation. In existing technologies, system pressure is measured at a single point. Since failure of individual components is often unavoidable, a failure of the pressure sensor can lead to loss of control of the regulation loop. Utility Model Content

[0003] The technical problem to be solved by the present invention is to provide a three-way pressure regulation circuit for a water electrolysis hydrogen production system, solve the problem that the pressure regulation system in the existing technical solution is prone to failure and loss of control, realize system pressure regulation that can be better applied to the water electrolysis hydrogen production system, improve the safety and stability of the operation of the water electrolysis hydrogen production system, and achieve stable hydrogen quality.

[0004] According to the technical solution of the present invention, the present invention provides a three-way pressure control circuit for a water electrolysis hydrogen production system, comprising an electrolytic cell, an oxygen separator, an oxygen scrubber, an oxygen-side gas-water separator, a pressure regulating valve and an emptying pipeline connected in sequence; the oxygen separator is connected to a liquid level transmitter, a first pressure transmitter, a second pressure transmitter and a third pressure transmitter, the first pressure transmitter, the second pressure transmitter and the third pressure transmitter are all connected to a control system, and the control system is connected to the pressure regulating valve.

[0005] Furthermore, the control system includes a first AI card, a second AI card and a third AI card. The first pressure transmitter, the second pressure transmitter and the third pressure transmitter are respectively connected to the first AI card, the second AI card and the third AI card. The first AI card, the second AI card and the third AI card are all connected to the three-centering logic function block, and the three-centering logic function block is connected to the pressure regulating valve.

[0006] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0007] The "three-center" method is typically used in relatively important control loops. It uses three redundant inputs for analog signals, with the middle value taken as the actual value. Water electrolysis hydrogen production systems have high requirements for system pressure stability during operation. The system pressure control loop is a critical loop. Using a "three-center" control loop in this loop can not only reduce system overpressure caused by failure of a single sensor device, but also enable the three signals to perform mutual deviation checks. That is, when the deviation of three measured values ​​at the same location is too large, the system loop needs to be checked immediately. This helps maintenance personnel quickly locate the fault point, making the system more reliable, thereby ensuring the safe and stable operation of the water electrolysis hydrogen production system and achieving stable hydrogen quality. The "three-center" control loop also serves as a reference for other important loops in the water electrolysis hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a structural diagram of the oxygen side of the water electrolysis hydrogen production system provided by the utility model.

[0009] Figure 2 It is a structural block diagram of the control system part provided by the utility model.

[0010] Figure 3 This is a control circuit diagram provided by the utility model.

[0011] Description of reference numerals in the accompanying drawings:

[0012] 1. Electrolyzer; 2. Oxygen separator; 3. Oxygen scrubber; 4. Oxygen-side gas-water separator; 5. Pressure regulating valve; 6. Drain pipe; 7. Liquid level transmitter; 8. First pressure transmitter; 9. Second pressure transmitter; 10. Third pressure transmitter; 11. Control system; 12. First AI card; 13. Second AI card; 14. Third AI card; 15. Three-centering logic function block. DETAILED DESCRIPTION

[0013] The utility model provides a three-way pressure regulation circuit for a water electrolysis hydrogen production system, which solves the problem that the pressure regulation system in the existing technical solution is prone to failure and loss of control, realizes system pressure regulation that can be better applied to the water electrolysis hydrogen production system, improves the safety and stability of the water electrolysis hydrogen production system operation, and achieves stable hydrogen quality.

[0014] See also Figure 1The present invention provides a three-way pressure control circuit for a water electrolysis hydrogen production system, comprising an electrolytic cell 1, an oxygen separator 2, an oxygen scrubber 3, an oxygen-side gas-water separator 4, a pressure regulating valve 5, and an exhaust line 6, which are connected in sequence. A liquid level transmitter 7 is connected to the oxygen separator 2 via a ring line. A first pressure transmitter 8, a second pressure transmitter 9, and a third pressure transmitter 10 are also connected to the ring line. The first, second, and third pressure transmitters 8, 9, and 10 are all connected to a control system 11, which is in turn connected to the pressure regulating valve 5.

[0015] In electrolyzer 1 (alkaline electrolyzer), water is electrolyzed into hydrogen and oxygen. On the oxygen side, a mixture of oxygen and alkaline solution flows through a pipeline into oxygen separator 2. The separated oxygen then flows into oxygen scrubber 3 for scrubbing and cooling, before entering oxygen-side gas-water separator 4 for drying and dehumidification. Finally, the output is controlled by pressure regulating valve 5 and discharged through exhaust pipeline 6. The opening of pressure regulating valve 5 is controlled by control system 11, thereby regulating the pressure (gas pressure) in the water electrolysis hydrogen production system (in the oxygen separator) to keep it within the required normal range.

[0016] More specifically, see Figure 2 The control system 11 includes a first AI card 12, a second AI card 13 and a third AI card 14. The first pressure transmitter 8, the second pressure transmitter 9 and the third pressure transmitter 10 are respectively electrically connected to the first AI card 12, the second AI card 13 and the third AI card 14 to transmit electrical signals. The first AI card 12, the second AI card 13 and the third AI card 14 are all electrically connected to the three-centering logic function block 15 to transmit point signals. The three-centering logic function block 15 is electrically connected to the pressure regulating valve 5 to transmit point signals and control the opening of the pressure regulating valve 5.

[0017] In the existing technical solution, only one pressure transmitter is provided on the oxygen side. When it fails, the regulating circuit controlling the pressure regulating valve will lose control. While the failure of a single component is often unavoidable, the probability of two or more components failing at the same time is relatively small.

[0018] See also Figure 3 This solution uses three pressure transmitters at three pressure measurement points on the oxygen side of the water electrolysis hydrogen production system. The median value of the three redundant input pressure signals is used as the actual adjustment value. This value is used for pressure regulation and controls the opening of the pressure regulating valve via PID. In special circumstances, when one point is faulty, the average of the remaining two signals is taken. If another point is faulty, the third signal is automatically taken; this improves the system's ability to overcome random errors.

[0019] To further demonstrate the technical effects of the present invention, a specific redundant fault-tolerant judgment mechanism is provided below:

[0020] 1. Under triple redundancy (when all three pressure transmitters are normal), the two closest readings among the three transmitters are normally averaged (choose 2 from 3); if one of the three readings deviates significantly from the other two, the output of this transmitter is blocked, and the system switches to double redundancy and issues an alarm.

[0021] 2. Under double redundancy (one of the three pressure transmitters fails), the two transmitters are normally read with an average value (2 out of 2), or the reading that is close to (or deviates from) the historical record is read (1 out of 2). Furthermore, if the difference between the readings of the two transmitters exceeds a certain range, it means that one of the two pressure transmitters is faulty. The transmitter that deviates more (or less) from the historical record, or the transmitter with a larger (or smaller) pressure change rate, is blocked, and the system is switched to a single transmitter operating state and an alarm is issued.

[0022] More specifically, when the water electrolysis hydrogen production system is operating in automatic control mode, a pressure transmitter collects pressure signal values, outputting 4mA to 20mA. These are then connected to three AI cards in the DCS / PLC control system. The intermediate value is then determined by the three-way logic function block. When the measured system pressure (the value determined by the three-way logic function block according to the aforementioned mechanism) is lower than the set pressure, the PID control valve is used to decrease its opening. When the measured system pressure is higher than the set pressure, the PID control valve is used to increase its opening.

[0023] When the hydrogen production system is shut down, when the measured system pressure is greater than the set automatic pressure-maintaining pressure, the valve opening of the pressure regulating valve is increased to 50%; when the measured system pressure is less than the automatic pressure-maintaining pressure, the opening of the pressure regulating valve is adjusted to 0%.

[0024] In summary, the water electrolysis hydrogen production system has high requirements for system pressure stability during operation. The system pressure regulation circuit is a critical circuit. Using a "three-center" regulation circuit in this circuit can not only reduce system overpressure caused by single sensor equipment failure, but also enable the three signals to check for deviations from each other. In other words, when the deviation of three measured values ​​at the same location is too large, the system circuit needs to be checked immediately. This helps maintenance personnel quickly locate the fault point, making the system more reliable, thereby ensuring the safe and stable operation of the water electrolysis hydrogen production system and achieving stable hydrogen quality. The "three-center" regulation circuit also serves as a reference for other important circuits in the water electrolysis hydrogen production system.

Claims

1. A pressure three-way centering regulating circuit for a water electrolysis hydrogen production system, characterized in that: The invention comprises an electrolytic cell (1), an oxygen separator (2), an oxygen scrubber (3), an oxygen-side gas-water separator (4), a pressure regulating valve (5) and an exhaust pipe (6) which are connected in sequence; the oxygen separator (2) is connected to a liquid level transmitter (7), a first pressure transmitter (8), a second pressure transmitter (9) and a third pressure transmitter (10); the first pressure transmitter (8), the second pressure transmitter (9) and the third pressure transmitter (10) are all connected to a control system (11); and the control system (11) is connected to the pressure regulating valve (5).

2. The pressure three-centering regulating circuit of the water electrolysis hydrogen production system according to claim 1 is characterized in that: The control system (11) includes a first AI card (12), a second AI card (13) and a third AI card (14); the first pressure transmitter (8), the second pressure transmitter (9) and the third pressure transmitter (10) are respectively connected to the first AI card (12), the second AI card (13) and the third AI card (14); the first AI card (12), the second AI card (13) and the third AI card (14) are all connected to a three-centering logic function block (15); and the three-centering logic function block (15) is connected to the pressure regulating valve (5).

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