Alkaline electrolytic water hydrogen production system and control method suitable for sea

Abstract

The application discloses a kind of alkali electrolytic water hydrogen production systems and control methods suitable for sea.This system includes alkali electrolytic cell;Hydrogen side lye circulation loop and oxygen side lye circulation loop are independently arranged;Hydrogen side vertical separator and oxygen side vertical separator are respectively connected to the independent lye circulation loop;And control system;The hydrogen production system of the application adopts double independent circulation framework to permanently isolate the path of hydrogen and oxygen gas mixing in external lye circulation loop physically, and completely eliminates the explosion risk caused thereby;The vertical separator of the application combines internal damping structure, effectively attenuates liquid level fluctuation;The application overcomes the problem that single liquid level signal is unreliable under the shaking of offshore environment, realizes the adaptive dynamic balance of system, fundamentally avoids false alarm and shutdown, and guarantees continuous production.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, and in particular to an alkaline water electrolysis hydrogen production system and its control method suitable for offshore floating platforms such as floating wind power platforms and ships in environments with continuous or irregular swaying. Background Technology

[0002] Against the backdrop of my country's "dual carbon" goals, offshore wind power has become a key method for utilizing renewable energy in coastal provinces in recent years due to its advantages such as high wind energy utilization rate, no land occupation, and proximity to energy consumption centers. The integration of offshore wind power with the hydrogen production industry is an important direction for the sustainable development of offshore wind power and has promising prospects for widespread application. Therefore, transferring mature land-based hydrogen production technologies to offshore floating platforms, such as floating wind power platforms, is a highly promising direction. However, in existing alkaline water electrolysis hydrogen production systems, the core component, the gas-liquid separator, has revealed design flaws in the dynamic marine environment.

[0003] Currently, alkaline water electrolysis hydrogen production systems used on land generally employ horizontal gas-liquid separators, typically connecting the hydrogen and oxygen mixtures within the same separator housing. The basic operating principle of this system is as follows: the hydrogen-alkaline mixture from the electrolyzer cathode and the oxygen-alkaline mixture from the anode enter a shared horizontal gas-liquid separator via separate pipelines. Although the separator is internally equipped with baffles that roughly divide the chamber into hydrogen and oxygen chambers, the two chambers are connected at the bottom via a connecting port, ultimately allowing the separated alkaline solutions to converge in a common alkaline pool. Subsequently, a shared circulating pump pressurizes the mixed alkaline solution, cools it, and then returns it to the electrolyzer.

[0004] If the gas-liquid separator of a land-based hydrogen production system is directly used at sea, it will face the problem of irregular and violent shaking of the floating platform during operation, resulting in the following issues: 1. Traditional horizontal gas-liquid separators have a large free liquid surface. Shaking causes the liquid surface to "slosh," resulting in fluctuating liquid level gauge signals, frequent false alarms, and system shutdowns, making continuous operation impossible.

[0005] 2. Shaking disrupts the separation environment and causes hydrogen and oxygen bubbles within the separator to violently flow with the alkaline solution. In a traditional single-cycle architecture, the hydrogen-containing and oxygen-containing alkaline solutions eventually mix, leading to cross-contamination of hydrogen and oxygen gases within the system, a decrease in purity, and the creation of an explosion hazard, posing an inherent safety risk.

[0006] 3. Conventional diaphragms and bipolar plates are prone to fatigue and damage under continuous mechanical stress, resulting in a sharp drop in system reliability.

[0007] Existing improvement solutions, such as using flexible pipelines and increasing the number of separator stages, can only alleviate local mechanical problems or improve the separation effect to a limited extent. They fail to provide a systematic solution in terms of system architecture, anti-sway design of core components, and intelligent control, and cannot meet the requirements for long-term safe and stable operation in harsh dynamic marine environments. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide an alkaline water electrolysis hydrogen production system and control method that can fully adapt to the dynamic swaying environment at sea in terms of system architecture, core component structure and control logic, and fundamentally solve the problems of safety, stability and continuous operation.

[0009] To achieve the above objectives, the present invention provides the following technical solution: An alkaline water electrolysis hydrogen production system suitable for marine applications includes: an alkaline electrolyzer; a hydrogen-side alkaline solution circulation loop and an oxygen-side alkaline solution circulation loop, which are independent of each other in terms of fluid passages and each includes a circulation pump and a heat exchanger to achieve independent circulation and physical isolation of the hydrogen-side and oxygen-side alkaline solutions. The hydrogen-side vertical separator and the oxygen-side vertical separator are respectively connected to their respective independent circulation loops; each of the vertical separators is equipped with a damping structure to suppress violent fluctuations in the internal fluid caused by platform shaking. The control system includes a controller and sensors for detecting the liquid level of the hydrogen-side separator, the liquid level of the oxygen-side separator, and the system pressure. The controller is configured to: receive the liquid level and pressure signals, fuse the hydrogen-side liquid level signal and the system pressure signal to generate a dynamic setpoint, and use the oxygen-side liquid level signal as the process feedback value. After calculation by a closed-loop control algorithm, the controller outputs a control signal to drive a pneumatic diaphragm regulating valve installed in the oxygen-side pipeline, thereby maintaining the dynamic balance of the liquid levels of the two separators.

[0010] In the above scheme, the damping structure is a physical structure that suppresses liquid surface sloshing by consuming fluid kinetic energy and disrupting regular fluctuations. It includes, but is not limited to, baffles, grid plates or packing layers. As a preferred embodiment, the damping structure is an inclined baffle or a horizontally arranged porous baffle.

[0011] In the above scheme, the baffle is a solid baffle with an inclination angle of 5-15 degrees. Through shaking and swaying simulation comparison, 6-10 degrees can most effectively prevent the liquid surface from shaking.

[0012] In the above scheme, the alkaline electrolytic cell is provided with a high mechanical strength composite diaphragm and a plate-mesh structure bipolar plate for supporting the diaphragm.

[0013] In the above scheme, the composite membrane comprises a porous reinforced framework layer and an alkali-resistant polymer microporous functional layer composite thereon.

[0014] In the above scheme, the porous reinforcing skeleton layer is a mesh structure woven from polyphenylene sulfide fibers or ceramic fibers.

[0015] In the above scheme, the material of the alkali-resistant polymer microporous functional layer is sulfonated polyether ether ketone. In the above scheme, the contact surface of the plate mesh structure bipolar plate is a continuous mesh support surface composed of raised ridges. The raised ridges form multiple recessed fluid micro-grooves, which are used to provide uniform elastic support for the composite diaphragm and accommodate its slight deformation.

[0016] In the above scheme, the closed-loop control algorithm is a PID control algorithm; the fusion processing includes weighted summation of the hydrogen side liquid level signal and the system pressure signal.

[0017] In the above scheme, the connecting pipes between the components of the system are at least partially flexible connecting pipes.

[0018] This invention also provides a control method for an alkaline water electrolysis hydrogen production system suitable for marine applications, comprising: S1: Real-time acquisition of hydrogen-side separator liquid level signal LH, oxygen-side separator liquid level signal LO, and system pressure signal P; S2: Based on the LH signal and the P signal, perform fusion processing to generate a dynamic setpoint L-set; S3: Using the LO signal as a process variable, compare it with the L-set, and calculate the control output using a PID control algorithm; S4: Adjust the action state of an actuator according to the control output so that the LO signal tracks the L-set, thereby achieving an adaptive dynamic balance of the liquid levels on both sides of the hydrogen-oxygen separator.

[0019] Traditional PID control algorithms, as a classic single-loop feedback controller, aim to enable the controlled variable to accurately and stably track a preset fixed setpoint or a single variable setpoint. This structure performs well in static or slowly changing systems where the measurement signal is reliable and the disturbance source is clear.

[0020] This invention addresses the unique dynamic environment of hydrogen production on floating platforms at sea. Instead of directly assigning a fixed value, it constructs a "dynamic setpoint generator" as a front-end intelligent unit for PID control. This unit receives multiple key parameters characterizing different system states in real time, particularly the hydrogen level signal LH and the system pressure signal P. Based on specific fusion rules, such as weighted fusion, it calculates an adaptively changing dynamic setpoint L-set online, which is then used as the tracking target for the PID controller.

[0021] Traditional PID control focuses solely on maintaining the stability of a single variable, LO, neglecting the coupling relationships between variables. This invention incorporates pressure P into the calculation of the dynamic setpoint, enabling the control target L-set to reflect and adapt to the overall pressure-level balance of the system in real time. When system conditions change, the controller can proactively and smoothly guide the system to a new optimal equilibrium point, achieving coordinated stability between the hydrogen and oxygen levels and the system pressure, thus improving the overall system safety.

[0022] This invention has positive effects: The hydrogen production system of this invention adopts a dual independent circulation architecture to physically and permanently isolate the path of hydrogen and oxygen gas mixing in the external alkaline solution circuit, completely eliminating the risk of explosion caused by this. The vertical separator of this invention, combined with an internal damping structure, effectively attenuates liquid level fluctuations. The plate mesh bipolar plate and composite diaphragm work together to form a robust combination resistant to mechanical stress, ensuring the long service life of core components. Based on the intelligent control algorithm of liquid level-pressure signal fusion, this invention overcomes the problem of unreliability of single liquid level signals under marine environmental swaying, realizes the adaptive dynamic balance of the system, fundamentally avoids false alarms and shutdowns, and ensures continuous production. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the system of the present invention.

[0024] Figure 2 This is a schematic diagram of the overall system structure of Embodiment 2 of the present invention.

[0025] Figure 3 This is a schematic diagram of the damping structure in Embodiment 2 of the present invention.

[0026] Figure 4 This is a logic block diagram of the control system of the present invention.

[0027] The attached figures are labeled as follows: 1-Alkaline electrolyzer; 2-Hydrogen-side vertical separator; 3-Oxygen-side vertical separator; 4-Controller; 5-Hydrogen-alkali solution circulation pump; 6-Oxygen-alkali solution circulation pump; 7-First baffle; 8-Second baffle; 9-Porous baffle one; 10-Porous baffle two; 11-Hydrogen-side liquid level sensor; 12-Oxygen-side liquid level sensor; 13-System pressure sensor; 14-Pneumatic diaphragm regulating valve. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1 This embodiment provides a method such as Figure 1 The illustrated system is an alkaline water electrolysis hydrogen production system suitable for offshore applications. Installed on a floating wind turbine platform, the system includes an alkaline electrolyzer 1, a hydrogen-side circulation unit, an oxygen-side circulation unit, and a controller 4. The alkaline circulation on the hydrogen and oxygen sides is completely independent and physically isolated in its fluid pathways. The hydrogen-side unit consists of a vertical hydrogen separator 2, a hydrogen-alkali circulation pump 5, a filter, and corresponding piping, forming an independent loop. The oxygen-side unit is symmetrically structured, consisting of an oxygen-side vertical separator 3, an oxygen-alkali circulation pump 6, a filter, and corresponding piping, forming an independent loop. There are no external mixing points between the alkaline solutions in the two loops.

[0031] like Figure 1 As shown, the hydrogen-side vertical separator 2 and the oxygen-side vertical separator 3 have the same structure. Their cylinder height-to-diameter ratio is 3:1. Two first baffles 7 inclined at 8° are installed in the internal liquid phase space, and two second baffles 8 inclined at 8° are installed in the gas phase space. All baffles 8, including the first and second baffles 7, are solid baffles, with a diameter of 4 / 5 of the cylinder's inner diameter. This structure has been verified through computational fluid dynamics sloshing simulation, effectively breaking up large liquid surface fluctuations and reducing the signal fluctuation amplitude at the hydrogen-side liquid level sensor 11 by more than 70%.

[0032] The alkaline electrolytic cell 1 employs a high-mechanical-strength composite diaphragm, formed by impregnating a polyphenylene sulfide woven mesh reinforcement with sulfonated polyether ether ketone. Matched with this is a plate-mesh structure bipolar plate, the side facing the diaphragm featuring a continuous mesh support surface composed of raised ridges. The raised ridges are 0.5 mm high, the ridge width is 0.3 mm, and the enclosed diamond-shaped fluid microchannels have an equivalent pore size of 2 mm. This structure provides uniform elastic support for the composite diaphragm and, under pressure fluctuations, accommodates its micro-deformation through the microchannels, collectively resisting sway stress.

[0033] like Figure 4 As shown, the controller 4 PLC receives the LH signal from the hydrogen-side liquid level sensor 11, the LO signal from the oxygen-side liquid level sensor 12, and the P signal from the system pressure sensor 13.

[0034] The control algorithm executed by controller 4 includes the following steps: S1: Real-time reading of LH, LO, and P.

[0035] S2: A weighted summation method is used to fuse the values, generating a dynamic setpoint L-set. The specific formula is: L-set = 0.4 * LH + 0.6 * P. The pressure signal P is given a higher weight of 0.6 because it is more stable and reliable under turbulent conditions.

[0036] S3: Using L-set as the setpoint and LO as the measured value, perform proportional-integral-derivative (PID) calculations to output a 4-20mA current control signal.

[0037] S4: The current signal drives the pneumatic diaphragm regulating valve 14 installed on the oxygen side outlet main pipeline via an electrical converter. By adjusting the opening of the pneumatic diaphragm regulating valve 14, the resistance of the oxygen side system is changed, thereby precisely regulating the liquid level of the oxygen side vertical separator 3, so that LO tracks L-set in real time and achieves dynamic balance.

[0038] Example 2 like Figure 2 , 3 The main difference between this embodiment and Embodiment 1 is the damping structure inside the vertical separator. Other structures, such as dual independent circulation, plate mesh bipolar plate, and control algorithm, are the same, to demonstrate the replaceability of the damping structure.

[0039] In this embodiment, the damping structure used to suppress sloshing is not a baffle plate, but a porous baffle, including one porous baffle 9 disposed in the liquid phase space of the separator and two porous baffles 10 disposed in the gas phase space. The porous baffles 9 and 10 are staggered, and each baffle occupies four-fifths of the inner diameter of the separator cylinder. Figure 3 As shown in the upper figure, after multiple layers are stacked, the entire inner diameter of the separator cylinder is equipped with perforated baffles.

[0040] When platform swaying causes violent liquid movement within the separator, the porous baffle, with its large surface area and pore channels, significantly increases the resistance to fluid flow, dissipating the kinetic energy of the liquid fluctuations. This transforms the macroscopic swaying of the liquid surface into microscopic turbulence within the pores, achieving efficient damping and stabilizing of the liquid surface. Testing has shown that this structure also meets the requirements for liquid level stability in swaying marine environments.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An alkaline water electrolysis hydrogen production system suitable for marine applications, characterized in that, include: Alkaline electrolytic cell; The hydrogen-side alkaline solution circulation loop and the oxygen-side alkaline solution circulation loop are set up independently. The hydrogen-side vertical separator and the oxygen-side vertical separator are respectively connected to the corresponding independent alkaline solution circulation loop; and, The control system includes a controller and a sensor group, the sensor group being used to acquire hydrogen-side separator liquid level, oxygen-side separator liquid level and system pressure signals; The controller is configured to generate dynamic setpoints based on the liquid level signal of the hydrogen-side separator and the system pressure signal, and output control signals through a closed-loop control algorithm with the liquid level signal of the oxygen-side separator as feedback, thereby adjusting the actuator to maintain the dynamic balance of the liquid levels of the two separators.

2. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 1, characterized in that: The hydrogen side-mounted separator and / or oxygen side-mounted separator are internally equipped with a damping structure to suppress fluid sloshing.

3. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 2, characterized in that: The damping structure includes inclined baffles.

4. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 3, characterized in that: The baffle plate is a solid baffle plate.

5. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 4, characterized in that: The solid baffle plate has an inclination angle of 5-15 degrees.

6. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 2, characterized in that: The damping structure includes a horizontally arranged porous baffle.

7. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 1, characterized in that: The alkaline electrolytic cell is equipped with a composite diaphragm and a plate-and-mesh bipolar plate.

8. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 1, characterized in that: The controller is configured to generate the dynamic setpoint by weighted fusion of the hydrogen-side separator level signal and the system pressure signal.

9. The alkaline water electrolysis hydrogen production system suitable for marine applications according to claim 1, characterized in that: The closed-loop control algorithm is a PID control algorithm; the actuator is a pneumatic diaphragm regulating valve installed on the oxygen side pipeline.

10. A control method for an alkaline water electrolysis hydrogen production system suitable for marine applications, characterized in that, include: S1: Real-time acquisition of hydrogen-side separator liquid level signal LH, oxygen-side separator liquid level signal LO, and system pressure signal P; S2: Based on the hydrogen-side separator liquid level signal LH and the system pressure signal P, perform weighted summation to generate a dynamic setpoint L-set; S3: Using the oxygen-side separator liquid level signal LO as a process variable, compare it with the dynamic setpoint L-set, and calculate the control quantity through the control algorithm; S4: Adjust the actuator according to the control quantity so that the oxygen-side separator level signal LO tracks the dynamic setpoint L-set.

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