A multi-alkali electrolytic tank waste heat storage and release system for off-grid micro-grid

Abstract

The application discloses an off-grid micro-grid multi-alkaline electrolytic cell waste heat storage and release system, comprising: a plurality of alkali liquor primary circuits, respectively connected with each alkaline electrolytic cell and not communicated with each other; a shared heat management network, comprising a shared heat medium main pipe filled with a heat medium and a heat medium circulating pump thereon; a heat storage unit connected with the shared heat medium main pipe; a first heat exchange unit, comprising a heat medium side heat exchange interface, a heat storage side heat exchange interface and a plurality of tank side heat exchange interfaces; a first heat exchange passage is formed between the tank side and the heat medium side heat exchange interface, and is used for bidirectional heat exchange between the alkali liquor primary circuit and the shared heat medium main pipe; a second heat exchange passage is formed between the heat medium and the heat storage side heat exchange interface, and is used for bidirectional heat exchange between the shared heat medium main pipe and the heat storage unit. The system realizes heat sharing under the premise of not mixing alkali liquor through alkali liquor isolation and indirect heat exchange, and guarantees the temperature control independence and high-temperature working condition safety of each alkaline electrolytic cell.

Description

Technical Field

[0001] This invention relates to the field of thermal management and energy storage control technology for hydrogen energy equipment, and more specifically to a waste heat storage and release system for multi-alkaline electrolyzers in an off-grid microgrid. Background Technology

[0002] In off-grid microgrid hydrogen production scenarios using renewable energy sources such as wind and solar power, the power output exhibits significant volatility, intermittency, and randomness. As a result, multiple alkaline electrolyzers typically cannot operate stably at their rated operating conditions for extended periods, instead exhibiting characteristics such as staggered startups, partial shutdowns, frequent load fluctuations, and repeated switching between hot and cold states.

[0003] To adapt to this dynamic power supply environment, electrolytic cell systems must frequently experience cold starts, standby insulation, low-load operation, and high-temperature heat dissipation. Traditional thermal management methods generally suffer from problems such as long start-up times, high start-up power consumption, large parasitic power consumption during standby insulation, and low utilization rate of operating waste heat when dealing with these dynamic conditions, which seriously restricts the overall energy efficiency and operational economy of the system. Therefore, there is an urgent need for a high-efficiency, collaborative, and low-energy-consumption thermal management technology suitable for off-grid microgrid multi-alkaline electrolytic cell scenarios.

[0004] Currently, the typical thermal management architecture for multi-alkaline electrolyzer systems in off-grid microgrids is a shared alkali solution loop system. This system includes multiple alkaline electrolyzers, a common main alkali solution circulation loop, a common circulation pump, and a common cooling unit. The alkali solution outlets of each alkaline electrolyzer are connected to the main supply pipe of the common main alkali solution circulation loop via branch valves, and the alkali solution inlets of each alkaline electrolyzer are connected to the main return pipe of the common main alkali solution circulation loop via branch valves. The common circulation pump is located on the common main alkali solution circulation loop to drive forced circulation of the alkali solution among all alkaline electrolyzers. The common cooling unit is connected to the common main alkali solution circulation loop to cool the circulating alkali solution. In this system architecture, the raw alkali solutions from each alkaline electrolyzer are directly mixed in the same common loop, and natural heat balance is achieved through the flow of the alkali solution between different alkaline electrolyzers.

[0005] However, when a branch of an alkaline electrolyzer in a low-temperature state is connected to the common alkaline solution main circulation loop, its low-temperature alkaline solution will directly mix with the high-temperature alkaline solution of the operating alkaline electrolyzer, causing a sudden drop in the inlet temperature of the operating cell and a decrease in the efficiency of the electrochemical reaction. At the same time, it causes disturbances in the circuit flow distribution and fluctuations in thermal conditions, which seriously affects the operational stability and safety of the system. Summary of the Invention

[0006] To address the problems existing in the aforementioned fields, this invention proposes an off-grid microgrid multi-alkaline electrolyzer waste heat storage and release system. By setting up multiple isolated alkaline primary circuits, the direct mixing path of low-temperature and high-temperature alkaline solutions is fundamentally eliminated, thereby avoiding disturbances to the system's thermal balance when alkaline electrolyzers are switched in or out. Through a first heat exchange path formed within the first heat exchange unit, bidirectional heat exchange occurs between each alkaline primary circuit and the shared heat transfer medium main pipe, enabling the release of waste heat from alkaline electrolyzers in operation and the absorption of heat from alkaline electrolyzers in standby or ready-to-start states. Through a second heat exchange path formed within the first heat exchange unit, bidirectional heat exchange occurs between the shared heat transfer medium main pipe and the heat storage unit, enabling cross-time period storage and on-demand release of heat.

[0007] To address the aforementioned technical problems, this invention discloses an off-grid microgrid multi-alkaline electrolyzer waste heat storage and release system, comprising: Multiple alkali primary circuits are connected to each of the alkaline electrolytic cells, and the primary circuits of the alkali solutions are not interconnected. A shared heat management network includes a shared heat medium main pipe and a heat medium circulation pump installed on the shared heat medium main pipe. The shared heat medium main pipe is filled with heat medium, and the heat medium circulation pump is used to drive the heat medium to circulate in the shared heat medium main pipe. A heat storage unit, connected to the shared heat medium main pipe, is used to store heat and release it as needed; The first heat exchange unit is a multi-port bidirectional heat exchange unit, including a heat medium-side heat exchange port, a heat storage-side heat exchange port, and multiple tank-side heat exchange ports. The tank-side heat exchange ports are respectively connected to each of the alkali solution primary circuits. The heat medium-side heat exchange ports are connected to the shared heat medium main pipe, and the heat storage-side heat exchange ports are connected to the heat storage unit. A first heat exchange path is formed between the tank-side heat exchange ports and the heat medium-side heat exchange ports for bidirectional heat exchange between the alkali solution primary circuit and the shared heat medium main pipe. A second heat exchange path is formed between the heat medium-side heat exchange ports and the heat storage-side heat exchange ports for bidirectional heat exchange between the shared heat medium main pipe and the heat storage unit.

[0008] Preferably, each of the alkali primary circuits is provided with a local circulation pump and a branch valve, which are connected in series in the alkali primary circuit. The local circulation pump is used to drive the alkali to circulate in each of the alkali primary circuits, and the branch valve is used to control the flow rate of the alkali to the first heat exchange unit.

[0009] Preferably, it further includes a second heat exchange unit and a common cooling unit; the second heat exchange unit is connected to the pipelines of each of the alkaline primary circuits and the common cooling unit, and is used to perform independent or group heat dissipation on the alkaline electrolytic cell whose temperature exceeds the safety threshold.

[0010] Preferably, the interfaces of the first heat exchange unit are connected by pipelines, and the pipelines are equipped with valve groups for controlling the on / off state and flow rate of the heat medium or alkali solution.

[0011] Preferably, the thermal storage unit is a sensible thermal storage device, a phase change thermal storage device, or a combination of the two.

[0012] Preferably, it also includes an auxiliary electric heating unit, which is connected to the pipeline where the shared heat medium main pipe and the heat storage unit are located, and is used to supplement the heat of the shared heat medium main pipe and the heat storage unit.

[0013] Preferably, it further includes a controller; the controller is electrically connected to the temperature sensors of each alkaline electrolytic cell, the heat medium circulation pump, the cell circulation pump, and the branch valves. The controller is used to control the heat distribution according to the real-time operating conditions of each alkaline electrolytic cell, and to adjust the speed of each cell circulation pump and the opening of the branch valves according to the temperature feedback of each alkaline electrolytic cell, so as to adjust the heat exchange intensity between each alkaline electrolytic cell and the first heat exchange unit.

[0014] Preferably, the controller is further configured to: When the temperature of the alkaline electrolyzer in operation is higher than the preset waste heat recovery threshold, the alkaline electrolyzer is allowed to release waste heat to the shared heat medium main pipe through the first heat exchange unit; And when the temperature of the alkaline electrolytic cell in standby mode is lower than the preset lower limit, the first heat exchange unit is controlled to transfer heat from the shared heat medium main pipe to the alkaline electrolytic cell; when the temperature rises to the preset upper limit, the heat transfer is stopped. And when multiple alkaline electrolyzers have preheating or heat preservation requirements at the same time and the heat supply of the shared heat medium main pipe is insufficient, the priority index of each alkaline electrolyzer is determined, and the heat is allocated according to the priority index from high to low.

[0015] Preferably, it also includes a method for the division of labor control of an off-grid microgrid multi-alkaline electrolyzer waste heat storage and release system, comprising the following steps: The controller identifies each alkaline electrolytic cell as being in a cold start, standby, running, or stopped state based on the temperature data collected in real time by the temperature sensors of each alkaline electrolytic cell. The controller determines the operating mode of each alkaline electrolyzer based on the identified operating conditions, the temperature difference between each alkaline electrolyzer, and the preset temperature threshold. The operating modes include: a waste heat recovery mode in which the waste heat generated by the alkaline electrolyzer in operation is transferred to the shared heat transfer medium main pipe through the alkaline solution primary circuit via the first heat exchange unit; a cold start mode in which the heat in the shared heat transfer medium main pipe is transferred to the alkaline solution primary circuit of the target cell through the first heat exchange unit; and a standby heat preservation mode in which the heat in the shared heat transfer medium main pipe is intermittently transferred to the alkaline solution primary circuit of the alkaline electrolyzer in standby mode via the first heat exchange unit. When multiple alkaline electrolytic cells need to absorb heat through the first heat exchange unit at the same time, and the heating capacity of the shared heat medium main pipe is insufficient, the controller allocates heat according to the priority index of each alkaline electrolytic cell. The controller adjusts the speed of the circulating pump in each alkaline electrolytic cell and the opening degree of each branch valve according to the feedback from the temperature sensor of each alkaline electrolytic cell, so as to adjust the heat exchange intensity between each alkaline electrolytic cell and the first heat exchange unit.

[0016] Preferably, the priority index is a weighted sum of the temperature difference of the alkaline electrolyzer, the urgency of startup, and a preset weight; wherein, the temperature difference is the difference between the current temperature and the target temperature of the alkaline electrolyzer; the urgency of startup is determined based on the time difference between the planned startup time and the current time, and the difference between the current temperature and the allowable startup temperature; the preset weight is a coefficient determined based on the rated hydrogen production capacity of the alkaline electrolyzer, the current hydrogen load demand, and the predicted power of the microgrid.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The off-grid microgrid multi-alkaline electrolyzer waste heat storage and release system proposed in this invention fundamentally eliminates the direct mixing path of low-temperature and high-temperature alkaline solutions by setting up multiple isolated alkaline primary circuits. This avoids disturbances to the system's thermal balance when alkaline electrolyzers are switched in or out, significantly improving the operational stability of the multi-cell system. Through a first heat exchange path formed within the first heat exchange unit, bidirectional heat exchange occurs between each alkaline primary circuit and the shared heat transfer medium main pipe, enabling each alkaline electrolyzer to achieve bidirectional heat transfer and real-time sharing without the need for alkaline mixing. Furthermore, through a second heat exchange path formed within the first heat exchange unit, bidirectional heat exchange occurs between the shared heat transfer medium main pipe and the heat storage unit. Excess heat in the shared heat transfer medium main pipe is stored in the heat storage unit, and heat is released from the heat storage unit to the shared heat transfer medium main pipe when needed. This achieves cross-period storage and on-demand release of operating waste heat, further reducing the dependence on auxiliary heating for cold starts. Attached Figure Description

[0018] Figure 1This is a diagram of the off-grid microgrid multi-alkaline electrolyzer waste heat storage and release system proposed in this invention; Figure 2 This is a flowchart of the working condition control method provided in an embodiment of the present invention; Figure 3 The above is a logic diagram for the priority allocation of heat in a multi-alkaline electrolytic cell provided in an embodiment of the present invention. Detailed Implementation

[0019] The following will refer to the appendices in the embodiments of the present invention. Figures 1-3 The technical solutions in the embodiments of the present invention will be clearly and completely described. It should be understood that the terminology used in the present invention is only for describing particular implementation methods and is not intended to limit the present invention.

[0020] The system proposed in this invention adopts a system architecture of "alkaline solution primary loop of each alkaline electrolyzer + shared heat medium main pipe + first heat exchange unit + heat storage unit". Each alkaline electrolyzer is equipped with an alkaline solution primary loop, and the primary loops of each alkaline solution are not interconnected. The original alkaline solution of each alkaline electrolyzer circulates within its own cell and does not directly mix with the original alkaline solution of other alkaline electrolyzers. The shared heat medium main pipe is filled with heat medium and is equipped with a heat medium circulation pump, which drives the heat medium to circulate in the shared heat medium main pipe. The first heat exchange unit is a multi-port bidirectional heat exchange unit, including a heat medium-side heat exchange interface, a heat storage-side heat exchange interface, and multiple cell-side heat exchange interfaces. The heat storage unit is connected to the shared heat medium main pipe and is used to store heat from the shared heat medium main pipe and release it as needed.

[0021] Based on this, the tank-side heat exchange interfaces are connected to each alkaline solution primary circuit, the heat medium-side heat exchange interface is connected to the shared heat medium main pipe, and the heat storage-side heat exchange interface is connected to the heat storage unit. A first heat exchange path is formed between the tank-side and heat medium-side heat exchange interfaces for bidirectional heat exchange between the alkaline solution primary circuit and the shared heat medium main pipe. A second heat exchange path is formed between the heat medium-side and heat storage-side heat exchange interfaces for bidirectional heat exchange between the shared heat medium main pipe and the heat storage unit. This enables the operating tank to release heat to the shared heat medium main pipe via the alkaline solution primary circuit, the tanks awaiting startup or in standby mode to extract heat from the shared heat medium main pipe via the alkaline solution primary circuit, and the switching between heat charging and heat dissipation between the heat storage unit and the shared heat medium main pipe. The second heat exchange unit consists of multiple tank-side second heat exchange interfaces and a common cooling unit. Each tank-side second heat exchange interface is located on each alkaline solution primary circuit and is used for independent or grouped heat dissipation of the target alkaline electrolytic cell under high-temperature conditions.

[0022] The controller integrates the real-time operating conditions and state of charge (SOC) of each alkaline electrolyzer. th Waste heat recovery threshold T recBased on standby temperature limits, hydrogen load demand, planned start-up time, and microgrid predicted power, pattern recognition, heat priority ranking, and heat flow distribution are performed on each tank.

[0023] Example like Figure 1 As shown, this invention proposes a waste heat storage and release system for off-grid microgrid multi-alkaline electrolyzers, comprising: Multiple alkali primary circuits are connected to each alkaline electrolytic cell, and the primary circuits of each alkali solution are not interconnected. A shared heat management network includes a shared heat medium main pipe and a heat medium circulation pump installed on the shared heat medium main pipe. The shared heat medium main pipe is filled with heat medium, and the heat medium circulation pump is used to drive the heat medium to circulate in the shared heat medium main pipe. The heat storage unit, connected to the shared heat medium main, is used to store heat and release it as needed; The first heat exchange unit is a multi-port bidirectional heat exchange unit, including a heat medium-side heat exchange port, a heat storage-side heat exchange port, and multiple tank-side heat exchange ports. The tank-side heat exchange ports are connected to each alkaline solution primary circuit, the heat medium-side heat exchange ports are connected to a shared heat medium main pipe, and the heat storage-side heat exchange ports are connected to the heat storage unit. A first heat exchange path is formed between the tank-side heat exchange ports and the heat medium-side heat exchange ports for bidirectional heat exchange between the alkaline solution primary circuit and the shared heat medium main pipe. A second heat exchange path is formed between the heat medium-side heat exchange ports and the heat storage-side heat exchange ports for bidirectional heat exchange between the shared heat medium main pipe and the heat storage unit.

[0024] Specifically, each alkaline electrolytic cell is equipped with its own circulation pump, supply and return pipelines, branch valves, temperature sensor, and bypass branch, forming an independent primary alkali circuit. These primary circuits are not interconnected; the original alkali solution in each cell circulates only within its own cell and does not directly mix with the original alkali solution from other cells. This avoids temperature and flow disturbances caused by the incorporation of low-temperature alkali solution from the cell to be started into the operating cell.

[0025] The shared heat transfer medium main is filled with heat transfer medium and is equipped with a heat transfer medium circulation pump, which drives the heat transfer medium to circulate within the main. The shared heat transfer medium main is also equipped with a heat transfer medium distribution valve assembly, as well as interfaces for the heat storage unit, cooling unit, and auxiliary heating unit. The shared heat transfer medium main is coupled to the primary circuit of each tank through a first heat exchange unit, achieving heat sharing rather than sharing the electrolyte itself.

[0026] The first heat exchange unit is a multi-port bidirectional heat exchange unit, including a tank-side heat exchange interface respectively disposed on each alkaline primary circuit, a heat medium-side heat exchange interface disposed on the shared heat medium main pipe, and a heat storage-side heat exchange interface disposed on the heat storage unit. A first heat exchange path is formed between the tank-side heat exchange interface and the heat medium-side heat exchange interface for bidirectional heat exchange between the alkaline primary circuit and the shared heat medium main pipe; a second heat exchange path is formed between the heat medium-side heat exchange interface and the heat storage-side heat exchange interface for bidirectional heat exchange between the shared heat medium main pipe and the heat storage unit. This achieves the following functions: through the first heat exchange path, the alkaline electrolyzer in operation releases waste heat to the shared heat medium main pipe via the alkaline primary circuit; the alkaline electrolyzer in standby or start-up state absorbs heat from the shared heat medium main pipe via the alkaline primary circuit; through the second heat exchange path, the heat storage unit releases heat to the shared heat medium main pipe or stores heat from the shared heat medium main pipe.

[0027] The system also includes a second heat exchange unit and a common cooling unit. The second heat exchange unit is connected to the piping of each alkali primary circuit and the common cooling unit, and is used to provide independent or group heat dissipation for alkaline electrolyzers whose temperature exceeds the safety threshold.

[0028] The interfaces of the first heat exchange unit are connected by pipelines, and the pipelines are equipped with valve groups for controlling the on / off state and flow rate of the heat medium or alkali solution.

[0029] The heat storage unit is connected to the shared heat medium main pipe to store heat from the shared heat medium main pipe and release heat back to the shared heat medium main pipe as needed. The heat storage unit can be a sensible heat storage device, a phase change heat storage device, or a combination of both.

[0030] It also includes an auxiliary electric heating unit, which is connected to the pipeline where the shared heat medium main pipe and the heat storage unit are located, and is used to supplement the heat of the shared heat medium main pipe and the heat storage unit when the heat of the heat storage unit is insufficient.

[0031] It also includes a controller, which is electrically connected to the temperature sensors, heat medium circulation pumps, and the circulation pumps and branch valves in the primary circuit of each alkaline electrolyzer. The controller is used to control the heat distribution according to the real-time operating conditions of each alkaline electrolyzer, and to adjust the speed of each circulation pump and the opening of each branch valve according to the temperature feedback of each alkaline electrolyzer, so as to adjust the heat exchange intensity between each alkaline electrolyzer and the first heat exchange unit.

[0032] The controller is also used to allow the alkaline electrolyzer to release waste heat to the shared heat transfer manifold through the first heat exchange unit when the temperature of the alkaline electrolyzer in operation is higher than the preset waste heat recovery threshold.

[0033] The controller is also used to control the first heat exchange unit to transfer heat from the shared heat medium main pipe to the alkaline electrolyzer when the temperature of the alkaline electrolyzer in standby state is lower than the preset lower limit; and to stop transferring heat when the temperature rises to the preset upper limit.

[0034] The controller is also used to determine the priority index of each alkaline electrolyzer when multiple alkaline electrolyzers have preheating or heat preservation requirements at the same time and the heat from the shared heat medium main pipe is insufficient, and to allocate heat according to the priority index from high to low.

[0035] The controller is also used to control the second heat exchange unit to independently or in groups dissipate heat from the alkaline electrolyzer when the temperature of the alkaline electrolyzer exceeds the safety threshold during operation.

[0036] To characterize the current thermal storage level of the thermal storage unit, this invention introduces the thermal storage state of charge (SOC). th This is used as an important input to the controller. It is defined as: SOC th =(Q th -Q th,min ) / (Q th,max -Q th,min ), where Q th Q represents the amount of heat storage currently available for the thermal storage unit. th,max Q is the rated maximum available heat storage capacity. th,min This represents the minimum available heat storage capacity.

[0037] SOC th The value range is 0 to 1; when SOC th =1 indicates full storage, when SOC th A value close to 0 indicates that the system is approaching its minimum available heat capacity. The remaining heat storage capacity can be calculated from 1 - SOC. th Characterization.

[0038] Waste heat recovery threshold T rec To determine whether the temperature of the alkaline electrolyzer in operation meets the temperature threshold for recovering excess heat, the operating temperature T of the alkaline electrolyzer is used. i Higher than T rec And the thermal storage unit is not fully charged (i.e., SOC). th When <1), the controller allows the alkaline electrolyzer to release waste heat to the shared heat transfer medium main pipe via the first heat exchange unit. rec Essentially, it is the dividing temperature at which "the alkaline electrolytic cell is allowed to supply heat to the outside after it has satisfied its own temperature maintenance."

[0039] Standby temperature preservation adopts a hysteresis control strategy, and a standby temperature limit T is set. stb,low and upper limit T stb,high When the temperature of the alkaline electrolytic cell in standby mode is lower than T stb,lowInitiate heat release and / or auxiliary heating when the temperature reaches T. stb,high Stop heat release and / or stop heating when necessary; maintain the current state between the upper and lower limits to avoid frequent start-stop of valves, pumps and heaters.

[0040] When multiple alkaline electrolyzers simultaneously require preheating or insulation and the heat supply from the shared heat transfer medium main is insufficient, the controller is configured with priority indicators.

[0041] The priority indicators are the weighted sum of the temperature difference of the alkaline electrolyzer, the urgency of startup, and the preset weights; where the temperature difference is the difference between the current temperature and the target temperature of the alkaline electrolyzer; the urgency of startup is determined based on the time difference between the planned startup time and the current time, as well as the difference between the current temperature and the allowable startup temperature; the preset weights are coefficients determined based on the rated hydrogen production capacity of the alkaline electrolyzer, the current hydrogen load demand, and the predicted power of the microgrid.

[0042] The priority indicators are as follows: PRI i =α1·ΔT i +α2·D i +α3·P i +α4·H i +α5·P mg,pred Where, ΔT i For the temperature difference in the alkaline electrolytic cell, D i To ensure the urgency of launching the plan, P i H represents the weight of the rated hydrogen production capacity of the alkaline electrolyzer. i As the weight of hydrogen load demand, P mg,pred For microgrid prediction, use relevant weights.

[0043] like Figure 2 The diagram shown is a flowchart of the working condition control method provided in this embodiment. The specific control logic is explained as follows: (1) Step S1 parameter acquisition: The controller collects in real time the inlet / outlet temperature, branch flow rate, shared heat medium supply and return temperature, heat storage unit temperature and heat storage state of charge (SOC) of each alkaline electrolyzer. th The status of the cooling unit, as well as the real-time available power and predicted power of the microgrid, provide input information for subsequent operating condition identification and heat dispatching.

[0044] (2) Step S2 Operating condition identification: The controller identifies the operating condition of each alkaline electrolyzer based on the current temperature, operating status and start-up / shutdown plan of each alkaline electrolyzer and classifies it into cold start, standby, running or shutdown status.

[0045] (3) Step S3 Waste heat recovery determination: The controller determines whether the alkaline electrolytic cell in operation meets the waste heat recovery conditions.

[0046] When the temperature T of the alkaline electrolyzer in operation i Satisfy T rec <T i <T safe Furthermore, the thermal storage unit is not fully charged (i.e., SOC). th When <1), it indicates that the alkaline electrolytic cell has the conditions to release excess heat to the outside and can enter the waste heat recovery process. Further, the controller opens the first heat exchange interface on the cell side corresponding to the alkaline electrolytic cell, so that the alkaline electrolytic cell releases waste heat to the shared heat medium main pipe through the first heat exchange unit, and transfers the heat to the heat storage unit for storage through the shared heat medium main pipe, thereby realizing the storage of waste heat during operation.

[0047] When the temperature T of the alkaline electrolytic cell in operation i If the above waste heat recovery conditions are not met, further determine whether T is met. i ≥T safe or SOC th If ≥1 is met, it indicates that the system has entered a high-temperature limited or heat storage limited state, and the system should be switched to a high-temperature heat dissipation process.

[0048] When switching to high-temperature heat dissipation mode, the controller opens the second heat exchange interface on the side of the alkaline electrolytic cell, so that the alkaline electrolytic cell exchanges heat with the common cooling unit through the second heat exchange unit to remove excess heat and ensure its safe operation.

[0049] When not switched to high-temperature heat dissipation mode, further determine whether there is an alkaline electrolytic cell in the current system that needs to be put into operation but has not yet reached the allowable start-up temperature and is in a cold start state. If so, the alkaline electrolytic cell enters the cold start mode; if not, further determine whether there is an alkaline electrolytic cell that needs to maintain a standby state within the standby temperature range.

[0050] In cold start mode, the controller prioritizes transferring heat from the shared heat medium main pipe to the alkaline solution primary circuit of the alkaline electrolyzer through the first heat exchange unit; when the heat in the shared heat medium main pipe is insufficient, the controller controls the heat storage unit to release heat to the shared heat medium main pipe to supplement it; when the heat in the heat storage unit is still insufficient, the auxiliary electric heating unit is started to supplement the heat, so that the alkaline electrolyzer completes the temperature rise and preheating in its alkaline solution primary circuit.

[0051] In standby heat preservation mode, the controller intermittently transfers heat from the shared heat transfer medium main pipe to the alkaline electrolyzer through the first heat exchange unit, and uses a hysteresis control strategy to maintain its temperature within the standby temperature range; when the temperature of the alkaline electrolyzer is lower than the standby lower limit T... stb,low Heat release and auxiliary heating are activated when the temperature reaches the standby upper limit T. stb,high Stop releasing heat and stop heating.

[0052] When there are no alkaline electrolyzers in the system that are either in a cold start state or in a standby state, the system enters a maintenance monitoring phase. The controller maintains the current system monitoring state and waits for the next control cycle to reassess the operating conditions of each alkaline electrolyzer.

[0053] Multi-cell heat priority allocation and closed-loop correction: When multiple alkaline electrolyzers simultaneously require preheating or insulation and the heat supply from the shared heat transfer main is insufficient, the controller allocates heat according to the priority index PRI. i Prioritize heat energy and combine it with the state of charge (SOC) of the stored heat. th The remaining heat release capacity and the predicted power of the microgrid are used to optimize the heat flow distribution, and the valve opening, heat medium flow rate and heat dissipation intensity are corrected in a closed loop according to the temperature response and changes in the heat storage state.

[0054] In this embodiment, a multi-cell system consisting of two or more alkaline electrolyzers is used as an example. Some alkaline electrolyzers are in operation, while others are in a standby or ready-to-start state. The alkaline electrolyzers in operation release waste heat to the shared heat transfer medium manifold through their first heat exchange interface on the cell side. The shared heat transfer medium manifold then transfers the heat to the heat storage unit for storage and directly to the cell requiring heat transfer. The alkaline electrolyzers in the ready-to-start state circulate at a low flow rate within their alkaline solution primary circuit and obtain heat from the shared heat transfer medium manifold and the heat storage unit through their corresponding interfaces. This allows for heat transfer between cells and preheating of the target cell without direct mixing of the original alkaline solutions.

[0055] Once the temperature of the alkaline electrolytic cell in the standby state reaches the standby temperature zone or the allowable operating temperature, the controller gradually increases its operating current and increases the speed of the circulating pump in the cell. During this process, if the alkaline electrolytic cell in the operating state does not release enough heat, the heat storage unit releases heat to the shared heat medium main pipe to supplement it. If it is still insufficient, the auxiliary electric heating unit will supplement the heat.

[0056] The temperature of the alkaline electrolyzer in standby mode drops to T. stb,low When the temperature reaches T, the controller opens the first heat exchange port on the cell side corresponding to the alkaline electrolyzer, allowing the shared heat transfer medium main pipe to transfer heat to the alkaline electrolyzer; when the temperature rises to T... stb,high It stops transferring heat at certain times, thus achieving standby hysteresis insulation. If the current SOC th If the temperature is low, the controller can reduce the heat preservation power, shorten the heat release duty cycle, or switch to auxiliary electric heating unit for compensation.

[0057] When the temperature of the alkaline electrolyzer in operation rises to T safe The above, or the thermal storage unit reaches full storage state (i.e., SOC). th=1) When the alkaline electrolyzer can no longer absorb heat, the controller cuts off the path for the alkaline electrolyzer to continue releasing heat to the shared heat medium main pipe, and opens the second heat exchange interface on the tank side corresponding to the alkaline electrolyzer, so that it can exchange heat with the common cooling unit through the second heat exchange unit, thereby implementing independent or group heat dissipation for the alkaline electrolyzer without affecting the normal operation of other alkaline electrolyzers.

[0058] like Figure 3 The diagram shown is a logic diagram for heat priority allocation in a multi-alkaline electrolyzer. The meanings of each module and decision node in the diagram are as follows: (1) Input parameter module: The controller inputs parameters that participate in the heat priority calculation, including the temperature difference ΔT of the alkaline electrolyzer. i Planned start time D i Rated hydrogen production capacity weight P i Hydrogen load demand weight H i and the microgrid predicted power related weight P mg,pred .

[0059] (2) Resource constraint module: The controller obtains the thermal storage unit's state of charge (SOC). th And the remaining heat that can be released, used to characterize the availability of currently shared heat resources.

[0060] (3) Priority Calculation Module: The controller calculates the priority index PRI of each target alkaline electrolyzer based on the input parameters. i This is used to characterize the priority order in which each target alkaline electrolyzer obtains heat resource security within the current control cycle.

[0061] (4) Sorting module: The controller sorts the data according to the PRI of each target alkaline electrolyzer. i The values ​​are sorted from largest to smallest to obtain the priority sequence of the target alkaline electrolyzer.

[0062] (5) "Are the resources sufficient to cover all target operating states of the alkaline electrolyzer? Judgment node: Controller integrated SOC" th The remaining releaseable heat and predicted available power are used to determine whether the current shared heat resources can meet the heat requirements of all target alkaline electrolyzers, including: The result corresponding to the "Yes" branch indicates that when the shared heat resources are sufficient to cover all target alkaline electrolyzers, the controller distributes heat to each target alkaline electrolyzer according to priority, and completes preheating or heat preservation control by adjusting the opening of the corresponding branch valves and the flow rate of the heat medium. The result corresponding to the "No" branch indicates that when the shared heat resources are insufficient to cover all target alkaline electrolyzers, the controller prioritizes the heat demand of high-priority alkaline electrolyzers, while switching to auxiliary heating, delaying startup, or continuing to wait for low-priority alkaline electrolyzers.

[0063] (6) Output results: The controller outputs the final heat distribution results, that is, it clarifies the heat supply sequence, heat distribution method and corresponding control measures of each target alkaline electrolyzer.

[0064] In this invention, multiple alkaline electrolyzers can simultaneously have both heat release and heat absorption requirements. The controller does not limit the unidirectional timing of "storage first, release later," but allows real-time heat transfer between alkaline electrolyzers and net charging / releasing of the heat storage unit to coexist. For example, alkaline electrolyzer A in operation meets the waste heat recovery conditions and needs to release heat to the shared heat medium main pipe through its first heat exchange interface on the cell side; alkaline electrolyzer B in the start-up state or alkaline electrolyzer C in the standby state needs to absorb heat from the shared heat medium main pipe through its corresponding first heat exchange interface on the cell side. At this time, the system can perform the following scheduling according to the heat balance relationship: when the heat release of alkaline electrolyzer A in operation is greater than the heat absorption of the target alkaline electrolyzer, the surplus is transferred to the heat storage unit for storage through the shared heat medium main pipe; when the heat release of alkaline electrolyzer A in operation is insufficient, the heat storage unit releases heat to the shared heat medium main pipe and / or the auxiliary electric heating unit makes up the difference.

[0065] Therefore, the first heat exchange unit should be understood as a multi-port bidirectional heat exchange system, rather than a single main heat exchanger. The shared heat transfer manifold is essentially a heat transfer carrier and buffer bus between multiple alkaline electrolyzers, while the heat storage unit acts as a heat buffer node, participating in net heat charging, net heat release, or only undertaking short-term buffering.

[0066] At the control level, the system proposed in this invention should preferentially avoid directly connecting the low-temperature alkaline solution of the alkaline electrolyzer in the standby state to the alkaline solution circuit of the operating tank. The alkaline electrolyzer in the standby state should first be preheated at a low flow rate in its own alkaline solution primary circuit through a shared heat transfer main pipe, and the load should be gradually increased after the allowable start-up temperature is reached.

[0067] The system proposed in this invention has the following technical advantages: First, by setting up primary circuits for each alkali solution, the direct integration of low-temperature alkali solution into the operating tank circuit is avoided, significantly reducing temperature and flow disturbances during independent start-up and shutdown of multiple tanks; Second, by utilizing the synergistic effect of operating waste heat, heat storage units, and auxiliary heating, the cold start time is effectively shortened and start-up power consumption is reduced; Third, by employing a standby hysteresis insulation strategy, parasitic power consumption during standby is reduced; Fourth, real-time heat transfer between multiple tanks and cross-period heat allocation of heat storage units can be achieved, significantly improving waste heat utilization efficiency; Fifth, under off-grid microgrid power fluctuation conditions, by combining the state of charge of heat storage, start-up plan, and predicted power execution priority allocation, the efficiency of heat resource utilization is improved; Sixth, by using independent or grouped cooling interfaces, the safety and temperature control independence of the system under high-temperature conditions are improved.

[0068] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0069] Furthermore, unless otherwise stated, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All references to this specification are incorporated by way of citation to disclose and describe methods relating to those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

Claims

1. A waste heat storage and release system for multi-alkaline electrolyzers in an off-grid microgrid, characterized in that, include: Multiple alkali primary circuits are connected to each of the alkaline electrolytic cells, and the primary circuits of the alkali solutions are not interconnected. A shared heat management network includes a shared heat medium main pipe and a heat medium circulation pump installed on the shared heat medium main pipe. The shared heat medium main pipe is filled with heat medium, and the heat medium circulation pump is used to drive the heat medium to circulate in the shared heat medium main pipe. A heat storage unit, connected to the shared heat medium main pipe, is used to store heat and release it as needed; The first heat exchange unit is a multi-port bidirectional heat exchange unit, including a heat medium-side heat exchange port, a heat storage-side heat exchange port, and multiple tank-side heat exchange ports. The tank-side heat exchange ports are respectively connected to each of the alkali solution primary circuits. The heat medium-side heat exchange ports are connected to the shared heat medium main pipe, and the heat storage-side heat exchange ports are connected to the heat storage unit. A first heat exchange path is formed between the tank-side heat exchange ports and the heat medium-side heat exchange ports for bidirectional heat exchange between the alkali solution primary circuit and the shared heat medium main pipe. A second heat exchange path is formed between the heat medium-side heat exchange ports and the heat storage-side heat exchange ports for bidirectional heat exchange between the shared heat medium main pipe and the heat storage unit.

2. The off-grid microgrid multi-alkaline electrolytic cell waste heat storage and release system according to claim 1, characterized in that, Each of the alkali solutions primary circuits is equipped with a local circulation pump and a branch valve. The local circulation pump and the branch valve are connected in series in the alkali solution primary circuit. The local circulation pump is used to drive the alkali solution to circulate in each of the alkali solution primary circuits, and the branch valve is used to control the flow rate of the alkali solution to the first heat exchange unit.

3. The off-grid microgrid multi-alkaline electrolytic cell waste heat storage and release system according to claim 1, characterized in that, It also includes a second heat exchange unit and a common cooling unit; the second heat exchange unit is connected to the pipelines of each of the alkaline primary circuits and the common cooling unit, and is used to provide independent or group heat dissipation for alkaline electrolyzers whose temperature exceeds the safety threshold.

4. The off-grid microgrid multi-alkaline electrolytic cell waste heat storage and release system according to claim 1, characterized in that, The interfaces of the first heat exchange unit are connected by pipelines, and the pipelines are equipped with valve groups for controlling the on / off state and flow rate of the heat medium or alkali solution.

5. The off-grid microgrid multi-alkaline electrolytic cell waste heat storage and release system according to claim 1, characterized in that, The heat storage unit is a sensible heat storage device, a phase change heat storage device, or a combination of the two.

6. The off-grid microgrid multi-alkaline electrolytic cell waste heat storage and release system according to claim 1, characterized in that, It also includes an auxiliary electric heating unit, which is connected to the pipeline where the shared heat medium main pipe and the heat storage unit are located, and is used to supplement the heat of the shared heat medium main pipe and the heat storage unit.

7. The off-grid microgrid multi-alkaline electrolytic cell waste heat storage and release system according to claim 2, characterized in that, It also includes a controller; the controller is electrically connected to the temperature sensors of each alkaline electrolytic cell, the heat medium circulation pump, the cell circulation pump, and the branch valves. The controller is used to control the heat distribution according to the real-time operating conditions of each alkaline electrolytic cell, and to adjust the speed of each cell circulation pump and the opening of the branch valves according to the temperature feedback of each alkaline electrolytic cell, so as to adjust the heat exchange intensity between each alkaline electrolytic cell and the first heat exchange unit.

8. The off-grid microgrid multi-alkaline electrolytic cell waste heat storage and release system according to claim 7, characterized in that, The controller is also used for: When the temperature of the alkaline electrolyzer in operation is higher than the preset waste heat recovery threshold, the alkaline electrolyzer is allowed to release waste heat to the shared heat medium main pipe through the first heat exchange unit; And when the temperature of the alkaline electrolytic cell in standby mode is lower than the preset lower limit, the first heat exchange unit is controlled to transfer heat from the shared heat medium main pipe to the alkaline electrolytic cell; when the temperature rises to the preset upper limit, the heat transfer is stopped. And when multiple alkaline electrolyzers have preheating or heat preservation requirements at the same time and the heat supply of the shared heat medium main pipe is insufficient, the priority index of each alkaline electrolyzer is determined, and the heat is allocated according to the priority index from high to low.

9. A method for division of labor control of a waste heat storage and release system for an off-grid microgrid with multiple alkaline electrolyzers according to any one of claims 1 to 8, characterized in that, Includes the following steps: The controller identifies each alkaline electrolytic cell as being in a cold start, standby, running, or stopped state based on the temperature data collected in real time by the temperature sensors of each alkaline electrolytic cell. The controller determines the operating mode of each alkaline electrolyzer based on the identified operating conditions, the temperature difference between each alkaline electrolyzer, and the preset temperature threshold. The operating modes include: a waste heat recovery mode in which the waste heat generated by the alkaline electrolyzer in operation is transferred to the shared heat transfer medium main pipe through the alkaline solution primary circuit via the first heat exchange unit; a cold start mode in which the heat in the shared heat transfer medium main pipe is transferred to the alkaline solution primary circuit of the target cell through the first heat exchange unit; and a standby heat preservation mode in which the heat in the shared heat transfer medium main pipe is intermittently transferred to the alkaline solution primary circuit of the alkaline electrolyzer in standby mode via the first heat exchange unit. When multiple alkaline electrolytic cells need to absorb heat through the first heat exchange unit at the same time, and the heating capacity of the shared heat medium main pipe is insufficient, the controller allocates heat according to the priority index of each alkaline electrolytic cell. The controller adjusts the speed of the circulating pump in each alkaline electrolytic cell and the opening degree of each branch valve according to the feedback from the temperature sensor of each alkaline electrolytic cell, so as to adjust the heat exchange intensity between each alkaline electrolytic cell and the first heat exchange unit.

10. The division of labor control method according to claim 9, characterized in that, The priority index is a weighted sum of the temperature difference of the alkaline electrolyzer, the urgency of startup, and a preset weight; wherein, the temperature difference is the difference between the current temperature and the target temperature of the alkaline electrolyzer; the urgency of startup is determined based on the time difference between the planned startup time and the current time, and the difference between the current temperature and the allowable startup temperature; the preset weight is a coefficient determined based on the rated hydrogen production capacity of the alkaline electrolyzer, the current hydrogen load demand, and the predicted power of the microgrid.

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