Alkaline water electrolysis hydrogen production low-power alkali liquor self-adaptive circulation system and control method

Abstract

The application discloses a kind of alkali water electrolysis hydrogen production low-power alkali liquor self-adaptive circulation system and control method, including composite ejector-pump alkali liquor circulation module and alkaline electrolytic water hydrogen production device;Composite ejector-pump alkali liquor circulation module includes alkali liquor pump and ejector;Alkaline electrolytic water hydrogen production device includes electrolytic cell and gas-liquid separator;Alkali liquor circulation pump output end is connected with the drive input end of ejector by second liquid inlet, and gas-liquid separator liquid outlet end connects the input end of alkali liquor circulation pump;Alkali liquor circulation pump input end is connected to the first liquid inlet of ejector by alkali liquor loop branch, and is connected with the injection input end of ejector;Ejector compression output end is connected to electrolytic cell, and electrolytic cell is connected with gas-liquid separator to form closed loop circulation system.The application improves the adaptability of alkaline electrolytic water system under wide load fluctuation range, and simultaneously, the power consumption of alkali liquor circulation pump is reduced, and the economy of alkali liquor circulation system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen production by alkaline electrolysis of water. More specifically, the present application relates to a low-power alkali solution self-adaptive circulation system and control method for hydrogen production by alkaline water electrolysis. BACKGROUND

[0002] Hydrogen has the characteristics of high energy density and environmental friendliness, and is an important green energy carrier in the future industrialization process. There are many ways to produce hydrogen, which can be divided into blue hydrogen, gray hydrogen and green hydrogen production modes according to the production process and by-products. The main way of green hydrogen production mode is water electrolysis, which can efficiently and continuously produce high-purity hydrogen through electrochemical decomposition of water. Among them, the alkaline water hydrogen production technology has a long history, and is widely used in large industrial fields due to its mature technology and durability.

[0003] In order to realize the high efficiency operation of the alkaline water electrolysis hydrogen production system, an alkali solution circulating pump is used to supply electrolyte to the electrolysis tank system, and an alkali solution tank is used to supplement the electrolyte to maintain the electrolysis efficiency. However, the alkaline water electrolysis hydrogen production system often faces power fluctuations, especially when it is stopped, started or combined with renewable energy. Using only the circulating pump for adjustment will cause the flow and pressure of the loop alkali solution to be unstable, thereby affecting the concentration overpotential on the electrode surface, ultimately causing the electrolysis hydrogen production efficiency of the alkaline electrolysis system to decrease and fluctuate, and affecting the purity of the produced gas. At the same time, the circulating pump faces technical challenges such as energy consumption optimization, cavitation protection, shock absorption and noise reduction. The ejector, as a pure mechanical structure, uses pressure difference and fluid shear stress to drive low-speed low-pressure fluid to recirculate, has the advantages of no parasitic power and low noise, and is widely used in the chemical industry.

[0004] However, most of the existing inventions of alkaline water electrolysis hydrogen production systems do not consider the technical challenges brought by the power increase of the alkali solution pump in actual work, lack dynamic response analysis of the alkaline water electrolysis hydrogen production equipment starting from the alkali solution circulation system, and lack an ejector-pump circulation system and control strategy for the alkaline water electrolysis hydrogen production device. When only the alkali solution circulating pump is used to control the alkali solution flow, if the system load changes rapidly and the power adjustment of the alkali solution circulating pump lags behind, the alkali solution flow rate may not be able to match the load change in time, the electrolyte temperature and ion concentration distribution are uneven, which leads to electrode polarization in local areas of the electrolysis tank, thereby increasing the required input voltage of the alkaline water hydrogen production electrolysis tank, and the optimal electrolysis efficiency of the alkaline water electrolysis hydrogen production system under different loads cannot be achieved. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides a low-power alkali water electrolysis hydrogen production self-adaptive alkali liquor circulating system, which adds an ejector in the alkali liquor circulating system to form a composite ejector-pump alkali liquor circulating module with the alkali liquor circulating pump. When the load of the electrolytic cell is unchanged, the power consumption of the alkali liquor circulating pump is reduced. The alkali liquor before entering the electrolytic cell is divided into two branches, the alkali liquor flow that needs to be accelerated by the circulating pump is reduced, and the power consumption is reduced. In the ejector, the kinetic energy of the alkali liquor in the branch stream through the alkali liquor circulating pump is fully utilized to re-accelerate the alkali liquor in the direct current without the alkali liquor circulating pump, effectively reducing the energy loss caused by the direct diffusion of electrolyte in the electrolytic cell. The alkali liquor at the outlet end of the ejector is fully mixed, the electrolyte flow rate entering the electrolytic cell is stable, the ion concentration distribution on the electrode surface is uniform, and the electrolysis efficiency is effectively improved.

[0006] Meanwhile, the present application provides a dynamic adjustable ejector. By setting a spring structure and a horizontally movable nozzle, the horizontal movement distance of the nozzle can be dynamically adjusted according to the output power of the alkali liquor circulating pump under the condition that the load is unchanged, the size of the suction chamber volume of the ejector is adjusted, the suction amount of the alkali liquor is changed, the fluid shear stress is maximally utilized, the intersection and mixing state of the alkali liquor is guided, and the high-speed stable alkali liquor enters the heat exchanger and the alkali liquor filter and is stably supplied to the electrolytic cell. The double dynamic adjustment of the ejector and the circulating pump realizes the self-adaptive demand of the system alkali liquor circulation, and reduces the influence of the performance change lag caused by adjusting only the alkali liquor circulating pump power when the load changes.

[0007] The technical scheme adopted by the present application to solve the technical problem is: a low-power alkali water electrolysis hydrogen production self-adaptive alkali liquor circulating system, comprising a composite ejector-pump alkali liquor circulating module and an alkaline electrolytic water hydrogen production device.

[0008] The composite ejector-pump alkali liquor circulating module comprises an alkali liquor pump and an ejector; the alkaline electrolytic water hydrogen production device comprises an electrolytic cell and a gas-liquid separator;

[0009] The alkali liquor circulating pump and the ejector are arranged in series, the output end of the alkali liquor circulating pump is connected to the driving input end of the ejector through a second liquid inlet, and the liquid outlet end of the gas-liquid separator is connected to the input end of the alkali liquor circulating pump; the input end of the alkali liquor circulating pump is connected to the first liquid inlet of the ejector through an alkali liquor loop branch and connected to the ejector input end; the compression output end of the ejector is connected to the electrolytic cell, and the electrolytic cell and the gas-liquid separator form a closed loop circulating system.

[0010] As a further scheme of the present application, an alkali liquor tank is further included, and an electric regulating valve is installed at the outlet of the alkali liquor tank.

[0011] The alkali liquor tank is connected to the liquid output end of the gas-liquid separator through a pipeline and before the composite ejector-pump alkali liquor circulating module.

[0012] As a further aspect of the present application, the cathode end and the anode end of the electrolytic cell are respectively connected to an independent alkali liquor circulation subsystem.

[0013] Each of the alkali liquor circulation subsystems comprises an alkali liquor circulation pump, an ejector, and a gas-liquid separator.

[0014] The compressed output end of the ejector of each alkali liquor circulation subsystem is connected to the electrolytic cell inlet through an independent pipeline.

[0015] As a further aspect of the present application, each independent alkali liquor circulation subsystem comprises a purification device and a post-processing device, and the gas outlet of the gas-liquid separator is connected to the purification device and the post-processing device through a pipeline.

[0016] As a further aspect of the present application, it further comprises an alkali liquor circulation heat exchanger and an alkali liquor filter, and the compressed output end of the ejector is connected to the electrolytic cell inlet through the alkali liquor circulation heat exchanger and the alkali liquor filter.

[0017] As a further aspect of the present application, the gas-liquid separators in the two independent alkali liquor circulation subsystems are connected in series through a pipeline.

[0018] As a further aspect of the present application, the ejector comprises a shell, a cavity, and an axially movable nozzle.

[0019] The cavity has a suction chamber and an isochoric mixing chamber inside, wherein the suction chamber is formed by the space surrounded by the inner wall of the cavity, the outer surface of the nozzle, and the inlet of the isochoric mixing chamber, the isochoric mixing chamber communicates with the suction chamber and the diffuser chamber, and the diffuser chamber is connected to the steady flow chamber.

[0020] One end of the cavity of the ejector is provided with a first alkali liquor inlet connected to the gas-liquid separator, and the other end of the cavity of the ejector is provided with an alkali liquor outlet.

[0021] The nozzle is internally provided with a second alkali liquor inlet connected to the output end of the alkali liquor circulation pump, and the nozzle is driven to move along the axis of the shell by the dynamic balance of the magnetic force generated by the energization of the electromagnetic winding and the spring pre-tensioning force, so as to dynamically adjust the merging point of the two alkali liquor streams in the suction chamber.

[0022] As a further aspect of the present application, it further comprises a sensing module and an alkali liquor circulation controller.

[0023] The sensing module comprises:

[0024] A capacitive liquid level meter installed at the top of the electrode chamber of the electrolytic cell is used to detect the liquid level difference on the cathode and anode sides. ;

[0025] Temperature sensors installed at the inlet and outlet of the electrolytic cell are used to obtain the temperature difference between the inlet and outlet. ;

[0026] Electromagnetic flowmeter installed at the compression output end of the ejector, used for monitoring the actual caustic soda flow ;

[0027] Mass flowmeter arranged at the output pipeline of the caustic soda tank, the mass flowmeter being located between the electric regulating valve and the caustic soda circulating pump

[0028] Caustic soda circulation controller, which is internally provided with:

[0029] Liquid level management module, which is configured to: Trigger a caustic soda supplement instruction, calculate a caustic soda supplement flow And control the electric regulating valve

[0030] Temperature difference flow conversion module, which is configured to generate a caustic soda circulation flow demand based on the temperature difference ΔT and an empirical coefficient k ;

[0031] Nozzle dynamic control module, which is configured to change the spring pre-tightening force by adjusting the electromagnetic winding current, so as to control the horizontal distance L between the nozzle outlet and the mixing chamber inlet

[0032] Synergistic optimization module: compare And Q, if , The flow tolerance deviation, the nozzle adjustment is started and the caustic soda circulating pump power is reduced

[0033] Backflow protection module: when the flow fluctuation at the compression end of the ejector is greater than 5% or backflow is detected, the caustic soda circulating pump power is increased

[0034] PID correction module: when Q exceeds the adjustable range of the ejector, the caustic soda circulating pump power is adjusted in steps to maintain ;

[0035] The caustic soda circulation controller forms a closed-loop control link of the caustic soda supplement and circulation flow through the mass flowmeter and the electromagnetic flowmeter.

[0036] The application also provides a control method of a low-power caustic soda self-adaptive circulation system for hydrogen production by alkaline water electrolysis, characterized by comprising the following sequentially executed closed-loop control steps:

[0037] 1) System state monitoring and demand calculation: the liquid level difference Δh of the anode and cathode sides of the electrolytic cell is monitored in real time through the capacitive liquid level meter, and a caustic soda supplement instruction is generated when Δh is lower than a set threshold value

[0038] The temperature difference ΔT of the electrolytic cell inlet and outlet is obtained through the temperature sensor, and the caustic soda circulation flow demand is calculated in combination with the preset empirical coefficients k, α and β ;

[0039] 2) Adaptive alkali replenishment control: When Δh is lower than the set threshold, the alkali circulation controller calculates the alkali replenishment flow rate. Where V is the volume corresponding to the liquid level difference, T is the preset replenishment time, and the electric regulating valve at the outlet of the alkali tank controls the liquid level difference according to Q. b Alkali replenishment;

[0040] The alkali replenishment flow rate is monitored by a mass flow meter and fed back to the alkali circulation controller to form a closed-loop regulation.

[0041] 3) Coordinated control of ejector and pump: If Effective and δ represents the allowable flow rate deviation, and dynamic adjustment of the ejector is performed:

[0042] a) By energizing the electromagnetic winding, the spring preload is changed, driving the nozzle to move axially;

[0043] b) Adjust the horizontal distance L between the nozzle outlet and the mixing chamber inlet to increase the volume of the suction chamber and enhance the Venturi effect;

[0044] c) Simultaneously reduce the power of the alkali circulation pump to the lowest feasible point;

[0045] Real-time monitoring of flow fluctuations at the ejector compression end: If the fluctuation amplitude is greater than 5% or backflow occurs, increase the power of the alkali circulation pump until the fluctuation is eliminated;

[0046] 4) Circulating pump power correction: When Q exceeds the adjustable range of the ejector, the circulating pump power is dynamically adjusted based on the PID algorithm: if Step-type booster pump power;

[0047] like Reduce pump frequency in a stepwise manner;

[0048] The PID parameters are corrected in real time by feedback from the electromagnetic flowmeter to maintain... .

[0049] The present invention has at least the following beneficial effects:

[0050] (1) The present invention adopts a composite ejector-pump alkali circulation system. The outlet of the alkali circulation pump is connected to the inlet of the ejector drive, which divides the alkali circuit at the liquid outlet of the gas-liquid separator into two branches. One branch is accelerated by the alkali circulation pump and enters through the inlet of the ejector drive. The negative pressure area formed by acceleration in the ejector suction chamber is used to draw in the alkali from the other branch ejected by the ejector inlet. This effectively reduces the working flow rate of the alkali circulation pump under the same load, thereby reducing the power consumption of the alkali circulation pump, improving the economy of the alkali circulation system, and reducing the operation and maintenance cost of the alkali circulation pump.

[0051] (2) This invention introduces an ejector component based on the Venturi effect. Through the geometric design of the cavity, the ejection efficiency is improved over a wide load range, making full use of the kinetic energy of the alkali solution accelerated by the alkali solution circulation pump and reducing energy loss during fluid convergence. At the same time, the design of the mixing chamber and the diffuser chamber stabilizes the pressure and flow rate of the mixed alkali solution and supplies it to the alkaline water electrolysis hydrogen production electrolyzer, reducing the electrolyte temperature and the gradient of ion concentration distribution on the electrode surface, as well as the concentration overpotential caused by an excessively high concentration gradient. This reduces the required input voltage of the alkaline water hydrogen production electrolyzer, effectively improving the overall electrolysis efficiency.

[0052] (3) The ejector described in this invention has a movable nozzle at the drive input end. The nozzle structure design allows the liquid to be directly injected into the suction chamber, preventing backflow and other unstable phenomena caused by load changes from filling the suction chamber and causing a decrease in the ejector's performance. At the same time, the axial movement of the nozzle structure can be achieved by cooperating with the electromagnetic winding and spring. By adjusting the axial distance between the nozzle outlet and the cross-section at the inlet of the isochoric mixing chamber, the entrainment and mixing effects of the alkaline liquid flow at the drive input end can be optimized when the load remains constant. The adjustable performance of the ejector and the alkaline liquid circulation pump ensure the adaptability of the alkaline water electrolysis hydrogen production system when the load changes.

[0053] (4) An alkaline circulating pump control strategy based on the current power and flow requirements of the alkaline water hydrogen production system was adopted. Therefore, a wider power control range of the alkaline pump can be guaranteed, reducing the loss problem caused by power mismatch due to excessive flow variation range, and enhancing the stability of alkaline water electrolysis hydrogen production system equipment.

[0054] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the alkaline water electrolysis hydrogen production system of the present invention;

[0056] Figure 2 This is a control block diagram of the composite ejector-pump alkali circulation device of the present invention;

[0057] Figure 3 This is an assembly diagram of the ejector described in this invention;

[0058] Figure 4 This is a diagram showing the initial position of the nozzle as described in this invention;

[0059] Figure 5 This is a diagram showing the position of the nozzle after it has moved, as described in this invention.

[0060] In the diagram: 1-Electrolytic cell; 2-Alkali filter; 3-Rectifier transformer; 4-Alkali tank; 5-Alkali circulation heat exchanger; 6-Alkali circulation pump; 7-Ejector; 8-Gas-liquid separator; 9-Purification equipment; 10-Gas collection and / or post-treatment equipment; 11-Alkali circulation controller; 701-Shell; 702-Cavity; 703-Nozzle; 704-Electromagnetic winding; 705-Spring; 706-First alkali inlet; 707-Second alkali inlet; 708-Suction chamber; 709-Isovolescent mixing chamber; 710-Diffuser chamber; 711-Flow stabilizing chamber. Detailed Implementation

[0061] The present invention will now be described in detail and completely with reference to the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention with reference to the accompanying drawings, it should be particularly noted that the technical solutions and features provided in various parts of the present invention, including the following description, can be combined with each other without conflict.

[0062] Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Example

[0063] like Figure 1 As shown, a low-power alkaline solution adaptive circulation system for alkaline water electrolysis hydrogen production is provided for alkaline solution replenishment in alkaline water electrolysis hydrogen production. The alkaline solution circulation systems on the cathode side and the anode side use the same components and adopt a symmetrical auxiliary equipment (Balance of Plant, BoP) system arrangement. Therefore, the working principle of the alkaline solution circulation system on the anode side is the same as that on the cathode side. This embodiment takes the alkaline solution circulation system on the anode side as an example as the main body of the description, and the alkaline solution circulation system on the cathode side will not be described again.

[0064] A low-power alkaline solution adaptive circulation system for alkaline water electrolysis hydrogen production includes a composite ejector 7-pump alkaline solution circulation module and an alkaline water electrolysis hydrogen production device. The composite ejector 7-pump alkaline solution circulation module includes an alkaline solution pump and an ejector 7. The alkaline water electrolysis hydrogen production device includes an electrolyzer 1 and a gas-liquid separator 8. The alkaline solution circulation pump 6 and the ejector 7 are arranged in series. The output end of the alkaline solution circulation pump 6 is connected to the drive input end of the ejector 7 through a second liquid inlet. The liquid outlet end of the gas-liquid separator 8 is connected to the input end of the alkaline solution circulation pump 6, accelerating the low-speed alkaline solution into a second alkaline solution branch through the alkaline solution circulation pump 6. The input end of the alkaline solution circulation pump 6 is connected to the first liquid inlet of the ejector 7 through an alkaline solution circuit branch, and is connected to the ejector input end of the ejector 7. The compression output end of the ejector 7 is connected to the electrolyzer 1. The electrolyzer 1 and the gas-liquid separator 8 are connected to form a closed-loop circulation system. During operation, the ejector 7 and the alkaline solution circulation pump 6 work together.

[0065] In the above technical solution, the low-speed alkaline liquid at the outlet of the gas-liquid separator 8 is the first alkaline liquid branch. After being accelerated by the alkaline liquid circulation pump 6, it is attracted by the shear stress generated by the high-speed flow formed by the second alkaline liquid branch in the ejector 7 and enters the ejector 7. Thereby, it is fully mixed with the second alkaline liquid branch to form a mixed alkaline liquid flow. The mixed alkaline liquid flow enters the alkaline liquid circulation heat exchanger 5 and the electrolytic cell 1 in sequence through the compression outlet of the ejector 7.

[0066] This technical solution may also include the following technical details to better achieve the technical effect: it also includes an alkali tank 4, the outlet of which is equipped with an electric regulating valve for accelerating the replenishment of alkali to the circulation system according to a set flow rate, and adjusting the power of the alkali circulation pump 6 according to the alkali circulation flow rate requirement.

[0067] The alkali tank 4 is connected by a pipe to the liquid output end of the gas-liquid separator 8 and the front of the compound ejector 7-pump alkali circulation module.

[0068] This technical solution may also include the following technical details to better achieve the technical effect: the cathode and anode of the electrolytic cell 1 are respectively connected to an independent alkali circulation subsystem;

[0069] Each of the aforementioned alkali circulation subsystems includes: an alkali circulation pump 6, an ejector 7, and a gas-liquid separator 8;

[0070] The compression output of the ejector 7 of each alkali circulation subsystem is connected to the inlet of the electrolytic cell 1 through independent pipelines.

[0071] This technical solution may also include the following technical details to better achieve the technical effect: Each independent alkali circulation subsystem includes a purification device 9 and a post-processing device. The gas outlet of the gas-liquid separator 8 is connected to the purification device 9 and the post-processing device through pipelines. After the gas-liquid separator 8 separates the gas from the alkali solution, the hydrogen gas is washed and cooled on the cathode side of the gas-liquid separator 8, and the oxygen gas is washed and cooled on the anode side of the gas-liquid separator 8. They then enter the purification devices 9 on the cathode side and the anode side, respectively, and are finally pressurized and stored in the gas collection and post-processing device.

[0072] This technical solution may also include the following technical details to better achieve the technical effect: it also includes an alkaline circulating heat exchanger 5 and an alkaline filter 2; the compression output end of the ejector 7 is connected to the inlet of the electrolytic cell 1 through the alkaline circulating heat exchanger 5 and the alkaline filter 2, and the alkaline circulating heat exchanger 5 is connected to an external cooling or energy storage system to form a circulating heat exchange loop.

[0073] This technical solution may also include the following technical details to better achieve the technical effect: the gas-liquid separators 8 in the two independent alkali circulation subsystems are connected in series through pipelines to avoid excessive pressure difference between the cathode side and the anode side.

[0074] like Figures 3-5 As shown, the ejector 7 is based on the Venturi ejection principle and includes: a housing 701, a cavity 702 and an axially movable nozzle 703;

[0075] The cavity 702 has an intake cavity 708, an isochoric mixing cavity 709, a diffuser cavity 710, and a flow stabilizing cavity 711. The isochoric mixing cavity 709 connects the intake cavity 708 and the diffuser cavity 710, and the diffuser cavity 710 is connected to the flow stabilizing cavity 711. The intake cavity 708 is a space enclosed by the inner wall of the cavity 702, the outer surface of the nozzle 703, and the inlet of the isochoric mixing cavity 709. The structure of the isochoric mixing cavity 709 and the flow stabilizing cavity 711 are the same in any cross section perpendicular to the axis. The diffuser cavity 710 has a cross section that gradually increases from the inlet to the outlet.

[0076] One end of the ejector 7 cavity 702 is provided with a first alkaline solution inlet 706 connected to the gas-liquid separator 8, and the other end of the ejector 7 cavity 702 is provided with an alkaline solution outlet;

[0077] The nozzle 703 has a second alkali inlet 707 connected to the output end of the alkali circulation pump 6. The nozzle 703 is driven to move along the axis of the housing 701 by the dynamic balance between the magnetic force generated by the energization of the electromagnetic winding 704 and the preload of the spring 705, so as to dynamically adjust the confluence point of the two alkali streams in the suction chamber 708. By moving the nozzle 703, the horizontal distance between the outlet of the nozzle 703 and the inlet of the equal volume mixing chamber 709 changes, adjusting the volume of the suction chamber 708 702 under different loads, thereby enhancing the ejection capability and further dynamically reducing the power consumption of the circulation pump, so that the composite ejector 7-pump alkali circulation module can adapt to different working conditions.

[0078] Work process:

[0079] Alternating current is applied to electrolytic cell 1, which is then converted to direct current by rectifier transformer 3 and enters electrolytic cell 1 as the site of electrochemical reactions. With the assistance of alkaline solution, the current passes through the electrodes to decompose water into hydrogen and oxygen. The generated hydrogen and oxygen, along with the circulating alkaline solution, enter the gas-liquid separator 8 from the outlet of electrolytic cell 1. Due to the density difference between gas and liquid, the gas-liquid separator 8 separates the gas from the alkaline solution under the action of gravity. Subsequently, the hydrogen is washed and cooled on the cathode side, and the oxygen is washed and cooled on the anode side, and then enters the purification equipment 9 on the cathode side and anode side, respectively. Finally, the gas is pressurized and stored in the gas collection and / or post-treatment equipment 10.

[0080] The water electrolysis hydrogen production system releases a large amount of heat during operation, heating the electrolyte solution. The temperature of the electrolyte solution affects the activation overpotential of the electrolysis process, thus impacting the energy efficiency of the system. The system employs an alkali circulation process; therefore, the electrolyte solution needs to be cooled before re-entering electrolyzer 1. An alkali circulation heat exchanger 5 is used to cool the separated circulating alkali solution, maintaining the temperature of electrolyzer 1 within its operating range. During operation, the hot circulating alkali solution exchanges heat with the cooling medium through the alkali circulation heat exchanger 5, thus cooling down. After absorbing heat, the cooling medium re-enters an external cooling or energy storage system to release the heat.

[0081] The composite ejector 7-pump circulation device removes mechanical impurities from the alkali solution after gas removal and then re-introduces it into the electrolytic cell 1. An alkali circulation controller 11 controls the alkali circulation pump 6, managing the flow rate of the alkali branch discharged from the liquid output end of the gas-liquid separator 8. After passing through the ejector 7-pump circulation module and the alkali circulation heat exchanger 5, it enters the alkali filter 2 to remove mechanical impurities before being introduced into the electrolytic cell 11, forming a closed-loop alkali system. Simultaneously, due to the continuous water consumption during electrolysis, the concentration of the circulating alkali solution continuously increases. Therefore, an alkali tank 4 needs to be added after the liquid output end of the gas-liquid separator 8 and before the composite ejector 7-pump circulation device. The prepared electrolyte is added to the alkali circulation system to adjust the concentration of the circulating alkali solution. Furthermore, the alkali tank 4 can adjust the flow rate into and out of the alkali circulation system in a timely manner to maintain a relative balance of the alkali flow rate in the circulation system when the load of the electrolytic cell 1 changes.

[0082] This technical solution may also include the following technical details to better achieve the technical effect: it also includes: a sensing module and an alkali circulation controller 11;

[0083] The sensing module includes:

[0084] The capacitive level gauge installed on the top of the electrode chamber of electrolytic cell 1 is used to detect the level difference Δh between the anode and cathode sides.

[0085] Temperature sensors installed at the inlet and outlet of electrolytic cell 1 are used to obtain the inlet and outlet temperature difference ΔT.

[0086] An electromagnetic flowmeter installed at the compression output end of ejector 7 is used to monitor the actual alkali flow rate. ;

[0087] A mass flow meter is installed on the output pipeline of the alkali tank 4, and the mass flow meter is located between the electric regulating valve and the alkali circulation pump 6.

[0088] The alkali circulation controller 11 has the following built-in features:

[0089] The liquid level management module calculates the alkali replenishment flow rate based on the Δh trigger alkali replenishment command. And control the electric regulating valve;

[0090] The temperature difference flow conversion module generates the alkali solution circulation flow requirement based on ΔT and the empirical coefficient k. ;

[0091] The nozzle 703 dynamic control module changes the preload of the spring 705 by adjusting the current of the electromagnetic winding 704, and controls the horizontal distance L between the nozzle 703 outlet and the mixing chamber inlet.

[0092] Collaborative optimization module: comparison With Q, if If δ is the allowable deviation of flow rate, then start nozzle 703 to adjust and reduce the power of alkali circulation pump 6;

[0093] Backflow protection module: When the flow fluctuation at the compression end of ejector 7 is greater than 5% or backflow is detected, the power of alkali circulation pump 6 is increased;

[0094] PID correction module: When Q exceeds the adjustable range of ejector 7, the power of alkali circulation pump 6 is maintained by stepwise adjustment. ;

[0095] The alkali circulation controller 11 forms a closed-loop control link between alkali replenishment and circulation flow through a mass flow meter and an electromagnetic flow meter.

[0096] In another embodiment, such as Figure 2 As shown, a control method for a low-power alkaline solution adaptive circulation system for alkaline water electrolysis hydrogen production is provided, including the following closed-loop control steps executed in sequence:

[0097] 1) System status monitoring and demand calculation: The liquid level difference Δh between the anode and cathode sides of electrolytic cell 1 is monitored in real time by a capacitive level gauge. When Δh is lower than the set threshold, an alkali replenishment command is generated.

[0098] The temperature difference ΔT between the inlet and outlet of electrolytic cell 1 is obtained by a temperature sensor. Combined with preset empirical coefficients k, α, and β, where k is the dominant coefficient for alkali circulation temperature difference, α is the current compensation coefficient, and β is the system's basic flow constant, the required alkali circulation flow rate is calculated. This directly translates thermal management requirements into flow control targets, strengthening the energy efficiency correlation of the entire system and thus solving the technical problem of uneven temperature distribution mentioned in the background technology; the empirical coefficients k, α, and β are obtained as follows:

[0099] A. Under typical system operating conditions, three sets of data are collected simultaneously: the DC current value I of the electrolytic cell, the inlet and outlet temperature difference ΔT, and the actual alkali flow rate of ejector 7. ;

[0100] B. Electrolytic cell 1 shall collect at least 20 sets of data under different operating conditions within the load range of 30% (low load standby) to 110% (overload operation). ;

[0101] C. Based on the heat-fluid balance equation, a model is established through linear regression: The coefficients k, α, and β are solved using the least squares method to ensure a fitting error ≤ 5%, and then stored in the temperature difference flow conversion module. The heat-flow balance equation originates from the total heat output P of electrolytic cell 1 and the convective heat transfer of the alkali solution. The steady-state equilibrium, that is , The density of the alkali solution is (kg / m³). The specific heat capacity of the alkali solution is given in J / kg·K. The alkali solution circulation flow rate requirement formula addresses the underestimation of flow rate under high current and low temperature difference conditions, and avoids flow overload under low current and high temperature difference conditions. It also resolves the flow matching lag problem caused by rapid load changes, as pointed out in the background technology. Furthermore, the automatic compensation system for flow deviations caused by aging (such as pipe scaling) eliminates the need for manual calibration.

[0102] 2) Adaptive alkali replenishment control: When Δh is lower than the set threshold, the alkali circulation controller 11 calculates the alkali replenishment flow rate. Where V is the volume corresponding to the liquid level difference, T is the preset replenishment time, and the electric regulating valve at the outlet of the alkali tank 4 is controlled according to... Alkali replenishment;

[0103] The alkali replenishment flow rate is monitored by a mass flow meter and fed back to the alkali circulation controller 11 to form a closed-loop regulation.

[0104] 3) Coordinated control of ejector 7 and pump: If Effective and δ represents the allowable flow rate deviation, and the ejector 7 is dynamically adjusted accordingly.

[0105] a) By energizing the electromagnetic winding 704, the preload of the spring 705 is changed, driving the nozzle 703 to move axially.

[0106] b) Adjust the horizontal distance L between the outlet of nozzle 703 and the inlet of mixing chamber to increase the volume of suction chamber 708 and enhance the Venturi effect;

[0107] c) Simultaneously reduce the power of the alkaline solution circulation pump 6 to the lowest feasible point;

[0108] Real-time monitoring of flow fluctuations at the compression end of ejector 7: If the fluctuation amplitude is >5% or backflow occurs, increase the power of alkali circulation pump 6 until the fluctuation is eliminated;

[0109] 4) Circulating pump power correction: When Q exceeds the adjustable range of ejector 7, the circulating pump power is dynamically adjusted based on the PID algorithm: if Step-type booster pump power;

[0110] like Reduce pump frequency in a stepwise manner;

[0111] The PID parameters are corrected in real time by feedback from the electromagnetic flowmeter to maintain... .

[0112] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A low-power alkali liquor self-adaptive circulation system for hydrogen production by alkaline water electrolysis, characterized in that, The application relates to a composite ejector-pump alkali liquid circulation module and an alkali electrolytic water hydrogen production device. The composite ejector-pump alkali liquid circulation module comprises an alkali liquid circulation pump and an ejector; the alkali electrolytic water hydrogen production device comprises an electrolytic tank and a gas-liquid separator, and a liquid outlet end of the gas-liquid separator is provided with an alkali liquid loop branch. The ejector comprises a shell, a cavity and an axially movable nozzle. The cavity is internally provided with a suction cavity and an isochoric mixing cavity, wherein the suction cavity is formed by a space surrounded by the cavity inner wall, the nozzle outer surface and the isochoric mixing cavity inlet, the isochoric mixing cavity communicates with the suction cavity and a diffuser cavity, and the diffuser cavity is connected with a steady flow cavity at the rear end. One end of the ejector cavity is provided with a first alkali liquid inlet which is communicated with the liquid outlet end of the gas-liquid separator through the alkali liquid loop branch, and the other end of the ejector cavity is provided with an alkali liquid outlet. The nozzle is internally provided with a second alkali liquid inlet which is communicated with the output end of the alkali liquid circulation pump, and the nozzle is driven to move along the shell axis by the dynamic balance of the magnetic force generated by the energization of the electromagnetic winding and the spring pre-tightening force, so as to dynamically adjust the merging point of the two alkali liquid streams in the suction cavity. The alkali liquid circulation pump and the ejector are arranged in series, the output end of the alkali liquid circulation pump is connected with the driving input end of the ejector through the second liquid inlet, the liquid outlet end of the gas-liquid separator is connected with the input end of the alkali liquid circulation pump, the input end of the alkali liquid circulation pump is connected with the first liquid inlet of the ejector through the alkali liquid loop branch, and the compression output end of the ejector is connected with the electrolytic tank. The first alkali liquid inlet is a first liquid inlet, and the second alkali liquid inlet is a second liquid inlet.

2. The low-power alkali solution self-adaptive circulation system for hydrogen production by alkaline water electrolysis according to claim 1, characterized in that, The alkali liquid tank is further provided with an electric regulating valve mounted on the outlet thereof. The alkali liquid tank is connected with the liquid output end of the gas-liquid separator through a pipeline and is arranged in front of the composite ejector-pump alkali liquid circulation module.

3. The low-power consumption alkali solution self-adaptive circulation system for hydrogen production by alkaline water electrolysis according to claim 2, characterized in that, The cathode end and the anode end of the electrolytic tank are respectively connected with an independent alkali liquid circulation subsystem. Each alkali liquid circulation subsystem comprises an alkali liquid circulation pump, an ejector and a gas-liquid separator. The compression output ends of the ejectors of the alkali liquid circulation subsystems are respectively connected with the electrolytic tank inlet through independent pipelines.

4. The low-power consumption alkali solution self-adaptive circulation system for hydrogen production by alkaline water electrolysis according to claim 3, characterized in that, Each independent alkali liquid circulation subsystem comprises a purification device and a post-processing device, and the gas outlet of the gas-liquid separator is connected with the purification device and the post-processing device through pipelines.

5. The low-power consumption alkali solution self-adaptive circulation system for hydrogen production by alkaline water electrolysis according to claim 4, characterized in that, The alkali liquid circulation module further comprises an alkali liquid circulation heat exchanger and an alkali liquid filter, and the compression output end of the ejector is connected with the electrolytic tank inlet through the alkali liquid circulation heat exchanger and the alkali liquid filter.

6. The low-power consumption alkali solution self-adaptive circulation system for hydrogen production by alkaline water electrolysis according to claim 3, characterized in that, The gas-liquid separators in the two independent alkali liquid circulation subsystems are connected in series through pipelines.

7. The low-power consumption alkali solution self-adaptive circulation system for hydrogen production by alkaline water electrolysis according to claim 1, characterized in that, The application further comprises a sensing module and an alkali liquid circulation controller. The sensing module comprises a mass flowmeter arranged on the output pipeline of the alkali liquid tank and located between the electric regulating valve and the alkali liquid circulation pump. ​ Capacitance liquid level meter installed on top of electrolytic cell electrode chamber for detecting liquid level difference on anode and cathode sides ; Temperature sensors are installed at the inlet and outlet of the electrolytic cell to obtain the temperature difference between the inlet and outlet ; Electromagnetic flowmeter mounted on the compression output end of an ejector for monitoring the actual caustic flow ; ​ The alkali liquor circulation controller is internally provided with a liquid level management module, a temperature difference flow conversion module, a cooperative optimization module, a counter flow protection module, a PID correction module and a nozzle dynamic control module; wherein the nozzle dynamic control module changes the spring pre-tightening force by adjusting the electromagnetic winding current to control the horizontal distance L between the nozzle outlet and the mixing chamber inlet; the alkali liquor circulation controller forms a closed loop control link of the alkali supplement and circulation flow by the mass flow meter and the electromagnetic flow meter.

8. The control method of the low-power alkali electrolytic hydrogen production self-adaptive caustic circulation system according to claim 7, characterized in that, The closed loop control steps include the following sequentially executed steps: 1) System state monitoring and demand calculation: the liquid level difference Δh of the anode and cathode sides of the electrolytic cell is monitored in real time by the capacitive liquid level meter, and the alkali supplement instruction is generated when Δh is lower than the set threshold value; Obtain temperature difference between inlet and outlet of electrolytic cell through temperature sensor , combine preset experience coefficients k, a and β to calculate lye circulation flow requirement ; wherein, k is lye circulation temperature difference leading coefficient, a is current compensation coefficient, β is system basic flow constant, and I is electrolytic cell direct current value 2) Adaptive make-up control: when Δh is below a set threshold, the lye circulation controller calculates the make-up flow where V is the volume corresponding to the liquid level difference, and T is the preset replenishment time. The electric regulating valve at the outlet of the lye tank is controlled according to make-up lye The alkali supplement flow is monitored by the mass flow meter and fed back to the alkali liquor circulation controller to form a closed loop regulation; 3) Ejector and pump coordinated control: if efficient and , δ is the flow tolerance deviation, the dynamic adjustment of the ejector is performed: a) The spring pre-tightening force is changed by the electromagnetic winding power to drive the nozzle axial movement; b) The horizontal distance L between the nozzle outlet and the mixing chamber inlet is adjusted to expand the suction chamber volume to enhance the Venturi effect; c) The alkali liquor circulation pump power is simultaneously reduced to the lowest possible point; The flow fluctuation at the compression end of the ejector is monitored in real time: if the fluctuation amplitude is >5% or counter flow occurs, the alkali liquor circulation pump power is increased to eliminate the fluctuation; 4) Circulating pump power correction: when Q exceeds the adjustable range of the ejector, the circulating pump power is dynamically adjusted based on the PID algorithm: if Q < Q , the circulating pump power is reduced in steps; If , the pump frequency is reduced stepwise; The PID parameters are corrected in real time by the electromagnetic flowmeter feedback to maintain .

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