High-pressure differential and fluctuation-resistant hydrogen production system using alkaline electrolysis

Abstract

The application discloses a high-pressure-difference-resistant and fluctuation-resistant operation alkaline electrolytic water hydrogen production system, which comprises a hydrogen separator and an oxygen separator, and an electrolytic tank is arranged between the hydrogen separator and the oxygen separator; the alkaline electrolytic water hydrogen production system further comprises an alkali liquor circulating unit, the alkali liquor circulating unit comprises a hydrogen-side circulating loop and an oxygen-side circulating loop which are independent of each other, the hydrogen-side circulating loop is connected with the hydrogen separator and the electrolytic tank, and the oxygen-side circulating loop is connected with the oxygen separator and the electrolytic tank. The alkaline electrolytic water hydrogen production system has the following advantages: the problem of low pressure difference tolerance and insufficient load response capability of a traditional system is solved, and the operation stability and safety of the system under fluctuation working conditions are significantly improved.

Description

Technical Field

[0001] This utility model relates to the field of water electrolysis hydrogen production technology, and in particular to an alkaline water electrolysis hydrogen production system and its control method that can operate stably under high hydrogen-oxygen pressure difference and has the ability to respond quickly to load fluctuations. Background Technology

[0002] Alkaline water electrolysis for hydrogen production is a mature, large-scale hydrogen production technology. However, its operation requires strict control of the pressure difference between the hydrogen and oxygen separators within a low range (typically no higher than 0.01 bar). Excessive pressure difference can lead to a significant increase in the liquid level difference between the hydrogen and oxygen separators, causing system interlock shutdowns and severely impacting operational continuity and hydrogen production efficiency. This is particularly critical in applications with fluctuating renewable energy power supply, where the system must frequently respond to load changes, placing extremely high demands on the real-time performance and reliability of pressure balance control.

[0003] In existing technologies, such as Figure 1 As shown, there is a connecting pipe between the oxygen separator and the hydrogen separator. The gas pressure difference between the hydrogen and oxygen sides needs to be strictly controlled (<0.1 bar) to ensure that the liquid level difference between the two sides is less than 100 mm. If the liquid level difference between the hydrogen and oxygen sides exceeds 100 mm, the system will shut down and the electrolyzer will no longer operate. Each of the oxygen and hydrogen separators is connected to a regulating valve. Currently, the pressure difference between the hydrogen and oxygen sides is entirely controlled by these regulating valves. Adjusting these valves requires more adjustment time and higher precision. If the electrolyzer load changes too much, the regulating valves are prone to causing a large pressure difference due to untimely adjustment, leading to a system shutdown. This makes it difficult to adapt to wide load fluctuations, has poor anti-interference capabilities, and results in frequent system start-ups and shutdowns, limiting its large-scale coupling application with fluctuating power supplies. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide an alkaline water electrolysis hydrogen production system that is resistant to high pressure differential and fluctuating operation, in order to solve the problems of low pressure differential tolerance and insufficient load response capability of traditional systems, and significantly improve the system's operational stability and safety under fluctuating conditions.

[0005] To solve the above technical problems, the present invention adopts the following technical solution: An alkaline water electrolysis hydrogen production system that is resistant to high pressure differential and fluctuation operation includes a hydrogen separator and an oxygen separator, with an electrolytic cell located between the hydrogen separator and the oxygen separator; The alkaline water electrolysis hydrogen production system also includes an alkaline solution circulation unit, which includes independent hydrogen-side circulation loops and oxygen-side circulation loops. The hydrogen-side circulation loops are connected to the hydrogen separator and the electrolyzer, and the oxygen-side circulation loops are connected to the oxygen separator and the electrolyzer.

[0006] Furthermore, the hydrogen-side circulation loop includes a hydrogen-side circulation pump installed on the pipeline between the electrolyzer and the hydrogen separator, and the oxygen-side circulation loop includes an oxygen-side circulation pump installed on the pipeline between the electrolyzer and the oxygen separator.

[0007] Furthermore, the hydrogen separator is connected to a buffer tank, and a hydrogen-side drain ball valve is installed on the pipeline between the hydrogen separator and the buffer tank. The oxygen separator is connected to a buffer tank, and an oxygen-side drain ball valve is installed on the pipeline between the oxygen separator and the buffer tank.

[0008] Furthermore, the alkaline water electrolysis hydrogen production system also includes a replenishment unit, which includes a buffer tank. The buffer tank is connected to a water tank via a pipeline, and the buffer tank is connected to a differential pressure transmitter #1, which monitors the liquid level in the buffer tank.

[0009] Furthermore, a replenishment pump, an oxygen-side replenishment ball valve, and a hydrogen-side replenishment ball valve are installed on the pipeline connecting the buffer tank to the top of the hydrogen separator and the oxygen separator. The oxygen-side replenishment ball valve is located on the pipeline connecting to the top of the oxygen separator, and the hydrogen-side replenishment ball valve is located on the pipeline connecting to the top of the hydrogen separator.

[0010] Furthermore, the alkaline water electrolysis hydrogen production system also includes a pressure detection unit, which includes a pressure sensor, a pressure transmitter, and a differential pressure transmitter. The pressure sensor is located on top of the hydrogen separator and the oxygen separator, and the pressure transmitter is installed on the oxygen separator. Both the hydrogen separator and the oxygen separator are connected to differential pressure transmitters for detecting the pressure difference between the hydrogen separator and the oxygen separator.

[0011] Furthermore, the alkaline water electrolysis hydrogen production system also includes a liquid level detection unit, which includes an oxygen-side differential pressure transmitter and a hydrogen-side differential pressure transmitter. The oxygen-side differential pressure transmitter and the hydrogen-side differential pressure transmitter are respectively installed in the oxygen separator and the hydrogen separator. The oxygen-side differential pressure transmitter is used to monitor the oxygen-side liquid level, and the hydrogen-side differential pressure transmitter is used to monitor the hydrogen-side liquid level.

[0012] Furthermore, the alkaline water electrolysis hydrogen production system also includes an execution unit, which includes a hydrogen-side pressure regulating valve installed on the hydrogen output pipeline and an oxygen-side pressure regulating valve installed on the oxygen output pipeline.

[0013] Furthermore, the alkaline water electrolysis hydrogen production system also includes a PLC control center, which is connected to an execution unit, a liquid level detection unit, a pressure detection unit, a hydrogen-side circulation pump, an oxygen-side circulation pump, and a replenishment pump. The PLC control center receives pressure and liquid level detection signals, controls the opening of the hydrogen-side pressure regulating valve to regulate the hydrogen-side pressure, and simultaneously controls the fluid transfer between the buffer tank and the hydrogen separator and oxygen separator to balance the liquid level and alkaline concentration.

[0014] Furthermore, the diaphragm of the electrolytic cell is a composite reinforced porous diaphragm.

[0015] The present invention adopts the above technical solution and has the following technical effects compared with the prior art: By enhancing the diaphragm's pressure resistance and employing a dual-loop independent circulation design, the system can withstand higher pressure differentials, significantly improving its adaptability to input power fluctuations. The introduction of an external buffer tank and a liquid level balancing mechanism effectively solves the problems of liquid level imbalance caused by pressure difference and performance instability caused by concentration difference. Decoupled control of pressure and liquid level, combined with differential pressure and oxygen-side pressure feedback, improves pressure regulation accuracy and system dynamic response speed; The system boasts high safety, significantly reduces the risk of hydrogen-oxygen mixing, and is suitable for hydrogen production scenarios involving highly volatile renewable energy sources. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. 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.

[0017] Figure 1 This is a schematic diagram of the structure of the water electrolysis hydrogen production system in the background art of this utility model; Figure 2 This is a schematic diagram of the structure of the water electrolysis hydrogen production system in an embodiment of this utility model. Detailed Implementation

[0018] Examples, such as Figure 2 As shown, an alkaline water electrolysis hydrogen production system that is resistant to high pressure differential and fluctuation operation includes a hydrogen separator 2, an oxygen separator 1, and an electrolysis cell 3 between the hydrogen separator 2 and the oxygen separator 1.

[0019] The alkaline water electrolysis hydrogen production system also includes an alkaline solution circulation unit, which comprises independent hydrogen-side circulation loops and oxygen-side circulation loops. The hydrogen-side circulation loop connects the hydrogen separator 2 and the electrolyzer 3, and the oxygen-side circulation loop connects the oxygen separator 1 and the electrolyzer 3. The hydrogen-side circulation loop includes a hydrogen-side circulation pump 6, which is installed on the pipeline between the electrolyzer 3 and the hydrogen separator 2. The hydrogen separator 2 is connected to a buffer tank 4, and a hydrogen-side drain ball valve 18 is installed on the pipeline between the hydrogen separator 2 and the buffer tank 4. The oxygen-side circulation loop includes an oxygen-side circulation pump 5, which is installed on the pipeline between the electrolyzer 3 and the oxygen separator 1. The oxygen separator 1 is connected to the buffer tank 4, and an oxygen-side drain ball valve 17 is installed on the pipeline between the oxygen separator 1 and the buffer tank 4. The oxygen flow goes from the oxygen separator 1 to the oxygen-side circulation pump 5, then to the electrolyzer 3, and then back to the oxygen separator 1; the hydrogen flow goes from the hydrogen separator 2 to the hydrogen-side circulation pump 6, then to the electrolyzer 3, and finally back to the hydrogen separator 2.

[0020] The alkaline water electrolysis hydrogen production system also includes a replenishment unit, which includes a buffer tank 4. The buffer tank 4 is connected to a water tank 19 via a pipeline. The water tank 19 is connected to a #2 differential pressure transmitter 20, which monitors the liquid level in the water tank 19. The buffer tank 4 is connected to a #1 differential pressure transmitter 13, which monitors the liquid level in the buffer tank 4. The inlet of the buffer tank 4 is connected to the bottom of the hydrogen separator and the oxygen separator via a pipeline. The outlet of the buffer tank 4 is connected to the top of the hydrogen separator and the oxygen separator via a pipeline. A replenishment pump 7, an oxygen-side replenishment ball valve 15, and a hydrogen-side replenishment ball valve 16 are installed on the pipeline connecting the buffer tank 4 to the top of the hydrogen separator and the oxygen separator, respectively. The oxygen-side replenishment ball valve 15 is located on the pipeline connecting to the top of the oxygen separator, and the hydrogen-side replenishment ball valve 16 is located on the pipeline connecting to the top of the hydrogen separator.

[0021] The alkaline water electrolysis hydrogen production system also includes a pressure detection unit, which includes a pressure sensor, a pressure transmitter 14, and a differential pressure transmitter 10. The pressure sensor is located on top of the hydrogen separator 2 and the oxygen separator 1. The pressure transmitter 14 is installed on the oxygen separator 1. Both the hydrogen separator 2 and the oxygen separator 1 are connected to the differential pressure transmitter 10 for detecting the pressure difference between the hydrogen separator 2 and the oxygen separator 1.

[0022] The alkaline water electrolysis hydrogen production system also includes a liquid level detection unit, which includes an oxygen-side differential pressure transmitter 11 and a hydrogen-side differential pressure transmitter 12. The oxygen-side differential pressure transmitter 11 and the hydrogen-side differential pressure transmitter 12 are respectively installed in the oxygen separator and the hydrogen separator. The oxygen-side differential pressure transmitter 11 is used to monitor the oxygen-side liquid level, and the hydrogen-side differential pressure transmitter 12 is used to monitor the hydrogen-side liquid level.

[0023] The alkaline water electrolysis hydrogen production system also includes an execution unit, which includes a hydrogen-side pressure regulating valve 9 installed on the hydrogen output pipeline and an oxygen-side pressure regulating valve 8 installed on the oxygen output pipeline.

[0024] The alkaline water electrolysis hydrogen production system also includes a PLC control center, which is connected to the execution unit, liquid level detection unit, pressure detection unit, hydrogen-side circulation pump 6, oxygen-side circulation pump 5 and replenishment pump 7. The PLC control center receives pressure and liquid level detection signals, controls the opening of the hydrogen-side pressure regulating valve to regulate the hydrogen-side pressure, and simultaneously controls the fluid transfer between the buffer tank and the hydrogen separator 2 and oxygen separator 1 to balance the liquid level and alkaline concentration.

[0025] A method for implementing an alkaline water electrolysis hydrogen production system that is resistant to high pressure differentials and fluctuations includes the following steps: Step 1: Pressure is monitored on the oxygen side by pressure transmitter 14, and then the pressure signal is transmitted to the PLC control center. The PLC control center compares the pressure with the set pressure and then controls the oxygen side regulating valve 8 to control the system pressure.

[0026] Step 2: The hydrogen-oxygen pressure balance is achieved by monitoring the pressure difference between the hydrogen and oxygen sides through the differential pressure transmitter 10, and then transmitting the pressure difference signal to the PLC control center. The PLC control center then compares the signal with the set pressure difference and controls the hydrogen-side regulating valve 9 to control the pressure balance between the hydrogen and oxygen sides.

[0027] Step 3: Separate pressure balancing and liquid level balancing. Since the electrolyzer reduces electrolyte solution permeation, the liquid level balancing in the hydrogen-oxygen separator needs to be adjusted via a buffer tank. First, the oxygen-side differential pressure transmitter 11 monitors the oxygen-side liquid level, and the hydrogen-side differential pressure transmitter 12 monitors the hydrogen-side liquid level. These hydrogen-oxygen liquid level signals are transmitted to the PLC control center and compared with the set liquid level difference. Then, the PLC control center controls either the hydrogen-side drain ball valve 18 or the oxygen-side drain ball valve 17 to open. Whichever side has a higher separator liquid level, the corresponding pneumatic ball valve opens to drain the liquid until the liquid level is below the set difference.

[0028] Step 4: The PLC control center compares the total liquid level of the hydrogen-oxygen separator transmitted in real time with the designed replenishment liquid level, and controls the replenishment pump 7 to replenish the liquid. When the replenishment pump is turned on, the differential pressure transmitter 13 of the buffer tank 4 monitors the liquid level in real time. When the liquid level is higher than the set liquid level in the PLC control center, the bottom outlet ball valve of the buffer tank is opened and the outlet ball valve of the water tank is closed. At the same time, the oxygen-side replenishment ball valve 15 or the hydrogen-side replenishment ball valve 16 are controlled respectively to replenish the liquid level in the hydrogen-oxygen separator to the set liquid level. When the liquid level in the buffer tank 4 is lower than the set liquid level in the PLC control center, the bottom outlet ball valve of the buffer tank is closed and the outlet ball valve of the water tank is opened to replenish the separator.

[0029] Step 5: The permeability of the electrolyte in the connected pipe and electrolytic cell decreases. During long-term electrolysis, the electrolyte concentration on both the hydrogen and oxygen sides will change, resulting in inconsistent electrolyte concentrations. This is addressed by periodically discharging a portion of the liquid from the hydrogen-oxygen separator into a buffer tank. This step is achieved by controlling the PLC control center to open the hydrogen-side drain ball valve 18 or the oxygen-side drain ball valve 17 at the bottom of the hydrogen-oxygen separator, discharging the set amount of liquid from the hydrogen-oxygen separator into the buffer tank for mixing. Then, following the same steps as in Step 4, the mixed electrolyte solution in the buffer tank is replenished into the hydrogen-oxygen separator. In this way, the electrolyte solution concentration will be controlled within a suitable range.

[0030] The electrolytic cell diaphragm is a composite reinforced porous diaphragm with a burst pressure of not less than 1.0 bar and a gas cross-permeability lower than that of traditional diaphragms.

[0031] The alkali circulation loops on the hydrogen and oxygen sides are completely independent. Differential pressure transmitter 10 detects the pressure difference between hydrogen separator 2 and oxygen separator 1, and transmits the signal to the control system. The control system maintains pressure balance by adjusting the opening of the hydrogen-side pressure regulating valve, keeping the hydrogen-oxygen pressure difference within a maximum range of -0.5 bar to +0.5 bar. The hydrogen-side and oxygen-side differential pressure transmitters monitor the separator liquid levels in real time. If the liquid level deviation exceeds the allowable value, the corresponding valve is opened to introduce alkali from the high-level side into the buffer tank, and then sent to the low-level side via the replenishment pump.

[0032] The system can operate continuously and stably for more than 5 minutes under a pressure difference of 0.5 bar, and can quickly respond to fluctuations of ±50% of the rated load. It is suitable for direct coupling hydrogen production from fluctuating power sources such as wind power and photovoltaic power.

[0033] The external buffer tank has a volume of not less than 20% of the effective volume of the separator, and its inlet and outlet are equipped with control valves that are interlocked with the liquid level signal.

[0034] The description of this utility model is given for illustrative and descriptive purposes only, and is not intended to be exhaustive or to limit the utility model to the forms 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 and practical application of the utility model, and to enable those skilled in the art to understand the utility model and design various embodiments with various modifications suitable for a particular purpose.

Claims

1. An alkaline water electrolysis hydrogen production system resistant to high pressure differential and fluctuation operation, characterized in that: It includes a hydrogen separator (2) and an oxygen separator (1), with an electrolytic cell (3) provided between the hydrogen separator (2) and the oxygen separator (1); The alkaline water electrolysis hydrogen production system also includes an alkaline solution circulation unit, which includes an independent hydrogen-side circulation loop and an oxygen-side circulation loop. The hydrogen-side circulation loop is connected to the hydrogen separator (2) and the electrolyzer (3), and the oxygen-side circulation loop is connected to the oxygen separator (1) and the electrolyzer (3).

2. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 1, characterized in that: The hydrogen-side circulation loop includes a hydrogen-side circulation pump (6), which is installed on the pipeline between the electrolyzer (3) and the hydrogen separator (2). The oxygen-side circulation loop includes an oxygen-side circulation pump (5), which is installed on the pipeline between the electrolyzer (3) and the oxygen separator (1).

3. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 1, characterized in that: The hydrogen separator (2) is connected to a buffer tank (4), and a hydrogen-side drain ball valve (18) is installed on the pipeline between the hydrogen separator (2) and the buffer tank (4). The oxygen separator (1) is connected to a buffer tank (4), and an oxygen-side drain ball valve (17) is installed on the pipeline between the oxygen separator (1) and the buffer tank (4).

4. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 1, characterized in that: The alkaline water electrolysis hydrogen production system also includes a replenishment unit, which includes a buffer tank (4). The buffer tank (4) is connected to a water tank (19) through a pipeline. The buffer tank (4) is connected to a #1 differential pressure transmitter (13), which monitors the liquid level of the buffer tank (4).

5. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 4, characterized in that: The buffer tank (4) is connected to the top of the hydrogen separator and the oxygen separator by a replenishment pump (7), an oxygen-side replenishment ball valve (15) and a hydrogen-side replenishment ball valve (16). The oxygen-side replenishment ball valve (15) is located on the top of the oxygen separator, and the hydrogen-side replenishment ball valve (16) is located on the top of the hydrogen separator.

6. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 1, characterized in that: The alkaline water electrolysis hydrogen production system also includes a pressure detection unit, which includes a pressure sensor, a pressure transmitter (14) and a differential pressure transmitter (10). The pressure sensor is located on the top of the hydrogen separator (2) and the oxygen separator (1), and the pressure transmitter (14) is installed on the oxygen separator (1). Both the hydrogen separator (2) and the oxygen separator (1) are connected to a differential pressure transmitter (10) for detecting the pressure difference between the hydrogen separator (2) and the oxygen separator (1).

7. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 1, characterized in that: The alkaline water electrolysis hydrogen production system also includes a liquid level detection unit, which includes an oxygen-side differential pressure transmitter (11) and a hydrogen-side differential pressure transmitter (12). The oxygen-side differential pressure transmitter (11) and the hydrogen-side differential pressure transmitter (12) are respectively installed in the oxygen separator and the hydrogen separator. The oxygen-side differential pressure transmitter (11) is used to monitor the oxygen-side liquid level, and the hydrogen-side differential pressure transmitter (12) is used to monitor the hydrogen-side liquid level.

8. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 1, characterized in that: The alkaline water electrolysis hydrogen production system also includes an execution unit, which includes a hydrogen-side pressure regulating valve (9) installed on the hydrogen output pipeline and an oxygen-side pressure regulating valve (8) installed on the oxygen output pipeline.

9. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 8, characterized in that: The alkaline water electrolysis hydrogen production system also includes a PLC control center, which is connected to an execution unit, a liquid level detection unit, a pressure detection unit, a hydrogen-side circulation pump (6), an oxygen-side circulation pump (5), and a replenishment pump (7). The PLC control center receives pressure and liquid level detection signals, controls the opening of the hydrogen-side pressure regulating valve to regulate the hydrogen-side pressure, and controls the fluid transfer between the buffer tank and the hydrogen separator (2) and the oxygen separator (1) to balance the liquid level and alkaline concentration.

10. The alkaline water electrolysis hydrogen production system with high pressure differential resistance and fluctuation resistance as described in claim 1, characterized in that: The diaphragm of the electrolytic cell (3) is a composite reinforced porous diaphragm.

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