A hydrogen content control system and method for hydrogen content in oxygen under low load state of an alkaline electrolytic water hydrogen production system

Abstract

The application discloses a kind of hydrogen content control system and method of hydrogen in oxygen under low load state of alkaline electrolytic water hydrogen system, including electrolytic cell, hydrogen separator, oxygen separator, lye cooler, temperature monitor and lye circulating pump.The system of the application along with the decline of electrolytic cell load, the operating temperature of lye of electrolytic cell also declines along with the decline of load, when the load of electrolytic cell drops below low load and operates, by lye cooler, the temperature of lye drops along with the decline of load, the temperature of lye drops synchronous control adjustment, both are according to corresponding proportional relationship and track adjustment control, to ensure that hydrogen in oxygen is controlled within the allowable safe range and operates, when the load fluctuates up and down, the controlled lye temperature tracks the load up and down and changes accordingly.

Description

A control system and method for controlling the hydrogen content in oxygen under low load conditions in an alkaline water electrolysis hydrogen production system. Technical Field

[0001] This invention belongs to the field of water electrolysis technology, specifically relating to a control system and method for controlling the hydrogen content in oxygen under low load conditions in an alkaline water electrolysis hydrogen production system. Background Technology

[0002] Gas purity is a crucial indicator in alkaline water electrolysis. The hydrogen produced during operation typically has a purity higher than 99.9 vol.% (without additional purification), while the oxygen produced is usually required to have a purity higher than 98.5 vol.%. Since these two product gases can form an explosive mixture within a range of approximately 4-96 vol.%, the technical safety limit for emergency shutdown of the entire electrolyzer system is 1.5 vol.%. Therefore, during operation, the hydrogen content in the product gas (oxygen) must be below this limit to ensure continuous operation and production of the hydrogen production system.

[0003] In the process of producing hydrogen through alkaline water electrolysis, the purity of the gas increases with the increase of current density. However, at lower current densities, the hydrogen content produced is lower, causing the hydrogen content in oxygen produced by alkaline water hydrogen production systems operating at low loads to exceed the required technical safety limit of 1.5 vol .% Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling hydrogen in oxygen under low-load operation of an alkaline water electrolysis hydrogen production system, so as to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A control system for controlling the hydrogen content in oxygen under low-load conditions in an alkaline water electrolysis hydrogen production system includes an electrolyzer, a hydrogen separator, an oxygen separator, an alkaline solution cooler, a temperature monitor, and an alkaline solution circulation pump.

[0007] The electrolytic cell is connected to a hydrogen separator and an oxygen separator, both of which are connected to an alkali cooler. The alkali cooler is connected to the electrolytic cell via an alkali circulation pump. An alkali temperature monitor is installed at the inlet of the electrolytic cell to monitor the temperature of the alkali solution. The alkali temperature monitor is connected to a central controller. When the central controller controls the electrolytic cell to operate at a low load, it controls the alkali cooler to lower the alkali temperature so that the temperature of the alkali solution in the electrolytic cell also decreases as the load decreases.

[0008] Preferably, the alkali circulation pump includes alkali circulation pump A or alkali circulation pump B, which transports the alkali in the alkali cooler to the electrolytic cell.

[0009] Preferably, the hydrogen separator is connected to a hydrogen synthesis tower, the hydrogen synthesis tower is connected to a hydrogen-water cooler, the hydrogen-water cooler is connected to a hydrogen-water separator, the hydrogen-water separator discharges unqualified hydrogen and qualified hydrogen in two separate streams, and the hydrogen-water separator is connected to a hydrogen drainer.

[0010] Preferably, the oxygen separator is connected to an aerobic integrated tower, the oxygen integrated tower is connected to an aerobic water cooler, the oxygen water cooler is connected to an oxygen water separator, the oxygen water separator discharges oxygen, and the oxygen water separator is connected to an aerobic drain.

[0011] A control method for controlling the hydrogen content in oxygen in an alkaline water electrolysis hydrogen production system under low load conditions, wherein the operating temperature of the alkaline solution in the electrolyzer varies according to the operating load of the electrolyzer.

[0012] Preferably, a low-load operating parameter range for the electrolyzer is set, and when the electrolyzer enters the low-load parameter range, the operating temperature control system of the alkaline solution in the electrolyzer system is activated to adjust the temperature.

[0013] Preferably, the operating temperature of the alkali solution in the electrolytic cell system is reduced as the operating load of the electrolytic cell decreases.

[0014] Preferably, the low-load operating parameter range of the electrolytic cell is set to 0-50% load.

[0015] Preferably, the temperature of the alkaline solution in the electrolyzer is controlled by a cooling water system, thereby stabilizing the outlet temperature of the electrolyzer within the range required for low load, so that the electrolyzer system can operate stably under low load conditions.

[0016] The technical effects and advantages of this invention are as follows: As the load on the electrolyzer decreases, the operating temperature of the alkaline solution in the electrolyzer also decreases accordingly. When the load on the electrolyzer drops below a low load, the alkaline solution temperature is controlled and adjusted synchronously with the load decrease through the alkaline solution cooler. The two are adjusted and controlled in a corresponding proportional relationship to ensure that the hydrogen in the oxygen is controlled within the allowable safe range. When the load on the electrolyzer fluctuates, the controlled alkaline solution temperature changes accordingly in response to the load fluctuations. Attached Figure Description

[0017] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0018] Figure 1 is a schematic diagram of the system of the present invention.

[0019] Figure 2 is a schematic diagram of the relationship between temperature and load in this invention. Detailed Implementation

[0020] To better understand the technical content of this invention, specific embodiments are described below in conjunction with the accompanying drawings. Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments of this disclosure are not necessarily defined to include all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed in this invention are not limited to any particular implementation. Furthermore, some aspects of this invention can be used alone or in any suitable combination with other aspects of this invention.

[0021] As shown in Figure 1, the present invention provides a control system for the hydrogen content in oxygen under low load conditions of an alkaline water electrolysis hydrogen production system, including an electrolyzer, a hydrogen separator, an oxygen separator, an alkaline cooler, a temperature monitor, and an alkaline circulating pump.

[0022] The electrolytic cell is connected to a hydrogen separator and an oxygen separator, both of which are connected to an alkali cooler. The alkali cooler is connected to the electrolytic cell via an alkali circulation pump. An alkali temperature monitor is installed at the inlet of the electrolytic cell to monitor the temperature of the alkali solution. The alkali temperature monitor is connected to a central controller. When the central controller controls the electrolytic cell to operate at a low load, it controls the alkali cooler to lower the alkali temperature so that the temperature of the alkali solution in the electrolytic cell also decreases as the load decreases.

[0023] The alkali circulation pump includes alkali circulation pump A or alkali circulation pump B, which transports the alkali in the alkali cooler to the electrolytic cell.

[0024] The hydrogen separator is connected to a hydrogen synthesis tower, the hydrogen synthesis tower is connected to a hydrogen-water cooler, the hydrogen-water cooler is connected to a hydrogen-water separator, the hydrogen-water separator discharges unqualified hydrogen and qualified hydrogen in two separate streams, and the hydrogen-water separator is connected to a hydrogen drainer.

[0025] The oxygen separator is connected to the aerobic integrated tower, the oxygen integrated tower is connected to the aerobic water cooler, the oxygen water cooler is connected to the oxygen water separator, the oxygen water separator discharges oxygen, and the oxygen water separator is connected to the aerobic drain.

[0026] To achieve the above objectives, the present invention provides another technical solution as follows:

[0027] A method for controlling the hydrogen content in oxygen under low load conditions in an alkaline water electrolysis hydrogen production system, wherein the operating temperature of the alkaline solution in the electrolyzer system varies according to the operating load of the electrolyzer.

[0028] Specifically, a low-load operating parameter range for the electrolyzer is set. Once the electrolyzer enters the low-load parameter range, the operating temperature control system of the alkali solution in the electrolyzer system is activated to regulate the temperature.

[0029] Specifically, the operating temperature of the alkali solution in the electrolytic cell system is reduced as the operating load of the electrolytic cell decreases.

[0030] Specifically, the low-load operating parameter range of the electrolytic cell is set to 0-50% load.

[0031] Specifically, the temperature of the alkaline solution in the electrolyzer is controlled by a cooling water system, thereby stabilizing the outlet temperature of the electrolyzer within the range required for low load. At this time, the electrolyzer system can operate stably under low load conditions.

[0032] Working principle: The automatic control system adopts a programmable logic controller (PLC). The system is configured with a Siemens 1500 series-1513 CPU master station + ET200sp slave station, with the PLC acting as the slave station. The entire alkaline water electrolysis hydrogen production system is in automatic mode. The hydrogen and oxygen side valves are automatically opened to maintain a continuous venting state. The hydrogen and oxygen side regulating valves, cooling water regulating valve, rectifier, circulating pump, and makeup water pump are in automatic mode. The alkaline solution inlet regulating valve is in manual mode at 50% opening. The rectifier current gain, current rise target value, and system pressure are set. The circulating pump is selected. Once ready, on-site personnel are notified for inspection. If no problems are found, the one-button start is pressed. If problems occur, the above steps are repeated.

[0033] Once the entire system reaches the set values ​​according to the pre-set parameters, and the pressure, temperature, flow rate, liquid level, oxygen-hydrogen ratio, and hydrogen-oxygen ratio are stable, the SV temperature setting of the cooling water regulating valve and the alkali inlet temperature are set to 40-70℃. This 40-70℃ range is not unique and can be set according to the user's actual needs. The PV temperature feedback value of the electrolytic cell inlet temperature and the SV setting value are used to calculate the appropriate regulating valve opening through PID control. Then, the inlet temperature is quickly reduced to the SV setting value, and the electrolytic cell outlet temperature also drops rapidly along with the inlet temperature. Finally, the current target is set to 50% load.

[0034] The regulating valves on both sides of the hydrogen and oxygen system rapidly reduce their openings as the load decreases and the gas production decreases, ensuring parameter stability after the operating conditions change.

[0035] At this point, the hydrogen content in oxygen fluctuates from a steady state to a rated value and then gradually decreases; Step 5: After reaching a steady state, the load is reduced sequentially to 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, and 5% in the same manner to achieve the final low-load operation target. Finally, under the premise of ensuring that the volume ratio of hydrogen in oxygen is within a safe value, the opening of the temperature regulating valve is measured to understand the relationship trend between the opening of the temperature regulating valve, temperature, and hydrogen content in oxygen, so that it can be adjusted accordingly to achieve safe production.

[0036] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control system for the hydrogen content in oxygen under low-load conditions in an alkaline water electrolysis hydrogen production system, characterized in that: The system includes an electrolytic cell, a hydrogen separator, an oxygen separator, an alkali cooler, a temperature monitor, and an alkali circulation pump. The electrolytic cell is connected to both the hydrogen and oxygen separators, which are in turn connected to the alkali cooler. The alkali cooler is connected to the electrolytic cell via the alkali circulation pump. An alkali temperature monitor is installed at the inlet of the electrolytic cell to monitor the temperature of the alkali solution. This monitor is connected to a central controller. When the central controller operates the electrolytic cell at a low load, it controls the alkali cooler to lower the alkali temperature, ensuring that the temperature of the alkali solution in the electrolytic cell decreases as the load decreases. The liquid circulation pump includes either alkali circulation pump A or alkali circulation pump B, which transports the alkali solution in the alkali cooler to the electrolytic cell; the hydrogen separator is connected to a hydrogen synthesis tower, the hydrogen synthesis tower is connected to a hydrogen-water cooler, the hydrogen-water cooler is connected to a hydrogen-water separator, the hydrogen-water separator discharges unqualified hydrogen and qualified hydrogen in two separate streams, and the hydrogen-water separator is connected to a hydrogen drainer; the oxygen separator is connected to an oxygen synthesis tower, the oxygen synthesis tower is connected to an oxygen-water cooler, the oxygen-water cooler is connected to an oxygen-water separator, the oxygen-water separator discharges oxygen, and the oxygen-water separator is connected to an oxygen drainer.

2. The control method for the control system of hydrogen content in oxygen under low load conditions in an alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The operating temperature of the alkaline solution in the electrolyzer varies according to the operating load of the electrolyzer.

3. The method for controlling the hydrogen content in oxygen under low-load conditions in an alkaline water electrolysis hydrogen production system according to claim 2, characterized in that: Set the low-load operating parameter range for the electrolyzer. Once the electrolyzer enters the low-load parameter range, activate the alkaline solution operating temperature control system in the electrolyzer system to regulate the temperature.

4. The method for controlling the hydrogen content in oxygen under low-load conditions in an alkaline water electrolysis hydrogen production system according to claim 2, characterized in that: The operating temperature of the alkali solution in the electrolytic cell system is reduced as the operating load of the electrolytic cell decreases.

5. The method for controlling the hydrogen content in oxygen under low-load conditions in an alkaline water electrolysis hydrogen production system according to claim 2, characterized in that: The low-load operating parameter range of the electrolytic cell is set to 0-50% load.

6. The method for controlling the hydrogen content in oxygen under low-load conditions in an alkaline water electrolysis hydrogen production system according to claim 5, characterized in that: The temperature of the alkaline solution in the electrolyzer is controlled by a cooling water system, thereby stabilizing the outlet temperature of the electrolyzer within the range required for low load. Under these conditions, the electrolyzer system can operate stably under low load.

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