Off-grid alkaline electrolysis total hot standby method based on multi-source waste heat deep integrated recovery

Abstract

The invention relates to the technical field of renewable energy source hydrogen production, and discloses an off-grid alkaline electrolysis total hot standby method based on multi-source waste heat deep integrated recovery, which comprises the following steps: S1, constructing a frame which comprises an electrolytic cell array, a graded waste heat recovery loop, a phase change heat storage tank and an auxiliary and emergency assembly; s2, synchronously capturing multi-source waste heat of the system: starting a circulating power assembly of a graded waste heat recovery loop, and synchronously collecting process cooling waste heat and product gas waste heat generated in the operation process of the electrolytic cell array through the graded waste heat recovery loop; and S3, heat storage and cascade distribution. By constructing an independent closed type grading waste heat recovery loop, alkali liquor cooling waste heat in the process of operating an electrolytic cell captures sensible heat of high-temperature wet oxygen at an outlet of an oxygen separator through the waste heat recovery heat exchangers connected in parallel, direct loss of the two kinds of waste heat is avoided, external power or fuel does not need to be relied on for supplying energy to hot standby, and energy consumption in the hot standby stage is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of renewable energy hydrogen production technology, specifically to an off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat. Background Technology

[0002] The off-grid alkaline electrolysis full-hot standby method is a thermal maintenance technology system designed for alkaline electrolysis hydrogen production systems disconnected from the public power grid. During shutdown or load fluctuation phases, it aims to maintain the electrolyzer, electrolyte solution, and related equipment at suitable operating temperatures. Its core objective is to ensure the system can quickly reach rated operating conditions upon restart, avoiding energy consumption spikes, equipment damage, and startup delays caused by low-temperature startup. The fundamental reason for implementing multi-source waste heat recovery is that off-grid alkaline electrolysis systems rely heavily on renewable energy sources. These energy sources are intermittent and unstable, causing the electrolysis system to frequently alternate between start-stop and load adjustments. During the hot standby phase, continuous heat replenishment is required to maintain thermal balance.

[0003] Currently, off-grid alkaline electrolysis systems often employ independent electric heating or fuel heating for hot standby. However, during operation, the waste heat generated is difficult to capture synchronously and efficiently, and a large amount of heat is directly dissipated through the cooling or exhaust system. This means that during the hot standby phase, external electric power is still required to drive the electric heater, or fossil fuels are consumed to maintain the temperature. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat, which solves the problem that the generated waste heat is difficult to capture synchronously and efficiently, and that a large amount of heat is directly lost through the cooling system or exhaust system.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat, comprising the following steps:

[0006] S1. Constructing a framework, the framework including an electrolytic cell array, a staged waste heat recovery loop, a phase change thermal storage tank, and auxiliary and emergency components;

[0007] S2. Synchronous capture system for multi-source waste heat: Start the circulating power component of the staged waste heat recovery loop to synchronously collect the process cooling waste heat and product gas waste heat generated during the operation of the electrolyzer array through the staged waste heat recovery loop;

[0008] S3. Heat storage and tiered distribution: When there is excess heat in the staged waste heat recovery loop, the excess heat is stored in the phase change heat storage tank. At the same time, the heat in the staged waste heat recovery loop is distributed to each heat reserve tank according to the priority of the heat reserve tank.

[0009] S4. Dynamically execute heat transfer between the operating tank and the hot standby tank: By controlling the flow switching component, regulate the heat transfer path between the staged waste heat recovery loop and the operating tank and the hot standby tank, realize the heat output from the operating tank to the staged waste heat recovery loop, and the heat input from the staged waste heat recovery loop to the hot standby tank.

[0010] S5. Dynamic scheduling of electrolyzers based on wind and solar power prediction: Adjust the number and operating status of operating cells and hot standby cells in the electrolyzer array according to the wind and solar power prediction results.

[0011] S6. Activate the safety redundancy protection mechanism, monitor the operating parameters of the staged waste heat recovery circuit and the system power supply status, and perform emergency handling operations when parameters are abnormal or power supply is interrupted.

[0012] Preferably, in step S1, the electrolytic cell array comprises at least two independently operating alkaline electrolytic cell units, each of which is switchable between a running cell and a hot standby cell, and the electrolytic cell array has reserved expansion interfaces.

[0013] The staged waste heat recovery loop is a closed-loop circulation pipeline filled with a heat-conducting medium. The staged waste heat recovery loop is equipped with a circulation power component, a temperature monitoring component, and a pressure monitoring component. The circulation power component is a variable frequency circulation pump, and the temperature monitoring component includes at least five thermometers. The phase change heat storage tank is filled with phase change material, and the phase change temperature of the phase change material matches the preset hot standby temperature range of the hot standby tank. The auxiliary and emergency components include a cooler, an emergency heat exchanger, a flow switching component, and an uninterruptible power supply. The flow switching component consists of at least two three-way valves. The cooler is connected to the alkaline solution circulation path of the electrolytic cell array, and the emergency heat exchanger is connected to the staged waste heat recovery loop.

[0014] Preferably, in step S2, the circulating power component includes a first waste heat recovery heat exchanger connected in parallel on the process alkali cooling path of the operating tank. The first waste heat recovery heat exchanger is connected to the staged waste heat recovery loop. When the reflux alkali from the operating tank flows through the first waste heat recovery heat exchanger, it transfers the process cooling waste heat to the staged waste heat recovery loop.

[0015] A second waste heat recovery heat exchanger is connected in series in the oxygen exhaust path of the oxygen separator. The second waste heat recovery heat exchanger is connected to the staged waste heat recovery circuit. When the high-temperature humid oxygen discharged from the oxygen separator flows through the second waste heat recovery heat exchanger, the waste heat of the product gas is transferred to the staged waste heat recovery circuit.

[0016] The temperature data corresponding to the process cooling waste heat and product gas waste heat are collected in real time by the temperature monitoring component. The speed of the variable frequency circulating pump is adjusted according to the temperature data collected by the temperature monitoring component, thereby regulating the circulation rate of the heat transfer medium in the staged waste heat recovery loop.

[0017] Preferably, in step S3, when the temperature of the staged waste heat recovery loop is higher than the preset heat standby requirement temperature of the heat standby tank, and the phase change material in the phase change storage tank has not reached the phase change saturation state, the heat transfer medium in the staged waste heat recovery loop is guided to transfer heat to the phase change storage tank, and the phase change material absorbs and stores the heat.

[0018] Determine the first start-up tank in the hot standby tank, prioritize the distribution of heat from the staged waste heat recovery loop to the first start-up tank, maintain the first start-up tank at the target hot standby temperature, and maintain the remaining hot standby tanks at a temperature lower than the target hot standby temperature; when the temperature of the staged waste heat recovery loop meets the target hot standby temperature requirements of all hot standby tanks, adjust the heat distribution ratio to ensure that all hot standby tanks are maintained at the target hot standby temperature.

[0019] Preferably, the dynamic execution of heat transfer between the operating tank and the hot standby tank in step S4 includes the following steps:

[0020] The temperature monitoring component monitors the total temperature of the staged waste heat recovery loop. When the total temperature exceeds the preset temperature threshold, the flow switching component controls the flow switching component to switch the alkali circulation path of the operating tank, so that the return alkali in the operating tank is switched from entering the first waste heat recovery heat exchanger to entering the cooler. The cooler cools down the alkali in the operating tank. The preset temperature threshold is the highest temperature that ensures effective cooling of the alkali in the operating tank.

[0021] When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop has dropped below the preset temperature threshold, the flow control switching component switches the alkaline circulation path of the operating tank again, so that the reflux alkaline solution of the operating tank is reconnected to the first waste heat recovery heat exchanger.

[0022] The flow control switching component connects the alkali circulation path of the hot standby tank to the staged waste heat recovery loop. The heat transfer medium in the staged waste heat recovery loop exchanges heat with the circulating alkali in the hot standby tank through the heat exchange component corresponding to the hot standby tank, which is used to heat the hot standby tank to maintain its temperature within the preset hot standby temperature range or to maintain the temperature.

[0023] Preferably, the dynamic scheduling of electrolyzers based on wind and solar power prediction in step S5 includes a wind and solar power sufficient or increasing condition, a wind and solar power insufficient or decreasing condition, and a wind and solar power severely insufficient condition in which all electrolyzers need to switch to hot standby condition.

[0024] The operating procedures for wind and solar power supply conditions that are sufficient or increasing are as follows:

[0025] Based on the wind and solar power forecast results, determine the number of new operating slots and the target hot standby slots that need to be switched to operating slots;

[0026] The heat transfer medium in the staged waste heat recovery loop is controlled to transfer heat to the target hot standby tank in a concentrated manner, so that the temperature of the target hot standby tank reaches the start-up temperature. The start-up temperature is the optimal initial temperature when the target hot standby tank is switched to the operating tank, and the start-up temperature is consistent with the preset hot standby temperature range.

[0027] When the actual wind and solar power reaches the starting power requirement of the target hot standby tank, the target hot standby tank is switched to the operating tank. At the same time, the next batch of hot standby tanks to be started is selected, and heat is transferred to the next batch of hot standby tanks to be started through a staged waste heat recovery circuit, so that the next batch of hot standby tanks to be started is maintained in the preset hot standby temperature range.

[0028] Preferably, the operating steps for the insufficient or reduced wind and solar power are as follows:

[0029] Based on the wind and solar power prediction results, determine the operating tanks that need to be deloaded and the corresponding deload slope;

[0030] The current of the tank that needs to be de-loaded is gradually reduced according to the preset de-load slope, so that the load of the tank that needs to be de-loaded gradually decreases.

[0031] When the load of the operating cell that needs to be unloaded drops to the preset minimum technical operating limit, the operating cell is disconnected from the operating circuit of the electrolytic cell array and the electrolytic reaction is stopped.

[0032] The operating tank that is cut out is guided to transfer residual heat to the staged waste heat recovery loop through the corresponding heat exchange components. Once the temperature monitoring component detects that the temperature of the cut-out operating tank has dropped to the preset hot standby temperature range or the maintenance temperature, it is switched to the hot standby tank.

[0033] Preferably, the following operation is performed when wind and solar power are severely insufficient and all electrolyzers need to be switched to hot standby mode:

[0034] Based on the wind and solar power prediction results, the shutdown sequence and corresponding shutdown load reduction slope of all operating slots are set in advance;

[0035] According to the set shutdown sequence and shutdown load reduction slope, the load of each operating tank is gradually reduced until all operating tanks stop electrolytic reaction;

[0036] After stopping all operating tanks, start the phase change heat storage tank to release the latent heat stored in the phase change material in the tank, and heat the heat transfer medium in the staged waste heat recovery loop.

[0037] The temperature of all hot standby tanks was lowered from the preset hot standby temperature range to the maintenance temperature. At the same time, the operation mode of the variable frequency circulating pump was adjusted, in which the variable frequency circulating pump operated in intermittent low frequency mode.

[0038] Prioritize guiding the heat transfer medium in the staged waste heat recovery loop to transfer heat to the first start-up tank, so that the temperature of the first start-up tank is maintained within the preset hot standby temperature range, while the temperature of the remaining hot standby tanks is maintained at the maintenance temperature.

[0039] Preferably, step S5 further includes the periodic switching operation between the running tank and the hot standby tank, with the following steps:

[0040] First, set the continuous operating time threshold for the alkaline electrolysis cell unit. When the continuous operating time of any operating cell reaches the continuous operating time threshold, or when the system enters the planned maintenance phase, determine the target hot standby cell that needs to be switched to the operating cell.

[0041] Within a preset time before switching, the preheating program of the target hot standby tank is started, and heat is transferred to the target hot standby tank through a staged waste heat recovery loop so that the temperature of the target hot standby tank reaches the start-up temperature.

[0042] Gradually reduce the load on the standby operating tank while increasing the load on the target hot standby tank until the load on the standby operating tank drops to zero and the load on the target hot standby tank reaches the rated operating load, thus completing the switch between the operating tank and the hot standby tank.

[0043] After the standby tank stops operating, residual heat is recovered through the corresponding heat exchange components. Once the temperature monitoring components detect that the temperature has dropped to the preset hot standby temperature range or maintained temperature, it switches to hot standby tank.

[0044] Preferably, the activation of the security redundancy protection mechanism in step S6 includes the following steps:

[0045] A temperature safety valve is installed on the staged waste heat recovery loop. When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop exceeds the safe temperature threshold and the phase change material in the phase change heat storage tank has reached the phase change saturation state, the temperature safety valve is opened and the emergency heat exchanger is started to cool the heat transfer medium in the staged waste heat recovery loop through the emergency heat exchanger.

[0046] When the main power supply of the system fails, the uninterruptible power supply is started to supply power to the temperature monitoring component, the flow switching component and the variable frequency circulating pump.

[0047] If there is a running slot in the system before the main power supply fails, the running slot is controlled to reduce the load to the shutdown state according to the preset load reduction slope, and then switched to the hot standby slot.

[0048] If the system is already in hot standby mode before the main power supply fails, maintain the intermittent low-frequency operation mode of the variable frequency circulating pump.

[0049] This invention provides an off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat. It has the following beneficial effects:

[0050] 1. This invention constructs an independent closed-loop staged waste heat recovery loop, which simultaneously recovers the waste heat from the cooling of the alkaline solution in the electrolytic cell process through parallel waste heat recovery heat exchangers, and the sensible heat and latent heat of condensation of the high-temperature humid oxygen at the outlet of the oxygen separator through series product gas waste heat recovery coolers. This avoids the direct loss of the two types of waste heat, eliminates the need to rely on external electricity or fuel for heat backup, and significantly reduces energy consumption during the heat backup phase.

[0051] 2. This invention integrates a heat storage tank filled with a material with a specific phase change temperature (PCM) in a staged waste heat recovery loop. The PCM phase change temperature matches the hot standby temperature range. When there is excess waste heat, it absorbs and stores latent heat. When wind and solar power is insufficient or waste heat is interrupted, it releases heat, realizing heat scheduling across time and space, and ensuring a hot standby state when there is no external input for a long time.

[0052] 3. Through pipeline design and three-way valve control, the present invention can flexibly switch the heat transfer path between the operating tank and the hot standby tank. The waste heat of the operating tank is fed into the staged waste heat recovery loop in real time, and the hot standby tank absorbs heat from the loop to maintain the standby temperature. When the temperature of the staged waste heat recovery loop exceeds the threshold, the three-way valve switches to the cooler to cool the alkaline solution in the operating tank, which not only ensures the stability of the main electrolysis process, but also maximizes the internal heat utilization efficiency.

[0053] 4. Based on wind and solar power prediction results, this invention dynamically manages the electrolytic cell cluster: when power is sufficient, parallel hot standby is executed to preheat multiple cells to be started; when power decreases, the load is gradually reduced, and cells with low load operation are switched out and put into hot standby; when power is severely insufficient, temperature hierarchical management is initiated to prioritize the temperature of the first cell to be started, ensuring that the system responds quickly to power fluctuations and can quickly resume operation.

[0054] 5. This invention establishes a dynamic model of waste heat production and electrolytic cell operating status, which can actively fine-tune operating parameters to match waste heat with heat backup requirements; at the same time, it is equipped with an emergency heat exchanger with a temperature safety valve and an uninterruptible power supply, which can start emergency cooling when heat accumulates abnormally, and maintain the operation of key components when the main power supply fails, so as to avoid equipment damage and ensure the long-term safety and stability of the system. Attached Figure Description

[0055] Figure 1 This is a flowchart of the method of the present invention;

[0056] Figure 2 This is a schematic diagram of the system architecture of the present invention. Detailed Implementation

[0057] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. 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.

[0058] Please see the appendix Figure 1 -Appendix Figure 2 This invention provides an off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat, comprising the following steps:

[0059] S1. Construction framework, which includes an electrolytic cell array, a staged waste heat recovery loop, a phase change thermal storage tank, and auxiliary and emergency components;

[0060] S2. Synchronous capture system for multi-source waste heat: Start the circulating power component of the staged waste heat recovery loop to synchronously collect the process cooling waste heat and product gas waste heat generated during the operation of the electrolyzer array through the staged waste heat recovery loop;

[0061] S3. Heat storage and tiered distribution: When there is excess heat in the staged waste heat recovery loop, the excess heat is stored in the phase change heat storage tank. At the same time, the heat in the staged waste heat recovery loop is distributed to each heat reserve tank according to the priority of the heat reserve tank.

[0062] S4. Dynamically execute heat transfer between the operating tank and the hot standby tank: By controlling the flow switching component, regulate the heat transfer path between the staged waste heat recovery loop and the operating tank and the hot standby tank, realize the heat output from the operating tank to the staged waste heat recovery loop, and the heat input from the staged waste heat recovery loop to the hot standby tank.

[0063] S5. Dynamic scheduling of electrolyzers based on wind and solar power prediction: Adjust the number and operating status of operating cells and hot standby cells in the electrolyzer array according to the wind and solar power prediction results.

[0064] S6. Activate the safety redundancy protection mechanism, monitor the operating parameters of the staged waste heat recovery circuit and the system power supply status, and perform emergency handling operations when parameters are abnormal or power supply is interrupted.

[0065] By adopting the above technical solution, a framework is constructed in S1, in which the electrolytic cell array provides the hardware foundation for switching between the operating cell and the hot standby cell, the staged waste heat recovery loop constitutes the heat transfer channel, the phase change heat storage tank has the function of heat storage, and auxiliary and emergency components are used to deal with abnormal operating conditions of the system.

[0066] In S2, the circulating power component of the staged waste heat recovery loop is activated. Through the staged waste heat recovery loop, the process cooling waste heat and product gas waste heat generated during the operation of the electrolytic cell array are collected synchronously. This can prevent the process cooling waste heat and product gas waste heat from being directly lost and provide a heat source for heating the hot standby tank without relying on external electricity or fuel to heat the hot standby tank.

[0067] In S3, when there is excess heat in the staged waste heat recovery loop, the excess heat is stored in the phase change heat storage tank. This storage process can release heat when there is insufficient heat in the subsequent staged waste heat recovery loop. At the same time, the heat in the staged waste heat recovery loop is distributed to each heat standby tank according to the priority of the heat standby tank, ensuring that the heat standby tank with high priority can continuously obtain heat to maintain the heat standby state, and avoiding disordered heat distribution that causes some heat standby tanks to be unable to maintain the heat standby state.

[0068] In S4, the heat transfer path between the staged waste heat recovery loop and the operating tank and the hot standby tank is regulated by controlling the flow switching component. This enables the heat output from the operating tank to the staged waste heat recovery loop, preventing the operating tank from being affected by heat accumulation and affecting the electrolysis conditions. At the same time, it enables the heat input from the staged waste heat recovery loop to the hot standby tank, ensuring that the temperature of the hot standby tank is maintained within the range that allows for rapid start-up, and avoiding the need for a long preheating period before the hot standby tank can be started due to excessively low temperature.

[0069] In S5, the number and operating status of the operating cells and hot standby cells in the electrolyzer array are adjusted according to the wind and solar power prediction results. When the wind and solar power is sufficient, the number of operating cells is increased to increase the hydrogen production. When the wind and solar power is insufficient, the number of operating cells is reduced and they are converted into hot standby cells to avoid frequent start-up and shutdown of the electrolyzer due to wind and solar power fluctuations and to reduce the thermal stress damage caused by frequent start-up and shutdown of the electrolyzer.

[0070] In S6, the operating parameters of the staged waste heat recovery loop and the power supply status of the system are monitored. When the operating parameters of the staged waste heat recovery loop are abnormal, emergency handling operations are performed to adjust the loop parameters to the normal range. When the power supply to the system is interrupted, emergency handling operations are performed to maintain the operation of key components, prevent equipment damage caused by abnormal parameters or power interruption, and ensure the continuous and stable operation of the system.

[0071] In step S1, the electrolytic cell array consists of no less than two independently operating alkaline electrolytic cell units. Each alkaline electrolytic cell unit is switchable between a running cell and a hot standby cell, and the electrolytic cell array has reserved expansion interfaces.

[0072] The staged waste heat recovery loop is a closed-loop pipeline filled with a heat-conducting medium. The loop is equipped with a circulation power component, a temperature monitoring component, and a pressure monitoring component. The circulation power component is a variable frequency circulation pump, and the temperature monitoring component includes at least five thermometers. The phase change heat storage tank is filled with phase change material, and the phase change temperature of the material matches the preset hot standby temperature range of the hot standby tank. The auxiliary and emergency components include a cooler, an emergency heat exchanger, a flow switching component, and an uninterruptible power supply. The flow switching component consists of at least two three-way valves. The cooler is connected to the alkaline circulation path of the electrolytic cell array, and the emergency heat exchanger is connected to the staged waste heat recovery loop.

[0073] By adopting the above technical solution, the electrolyzer array consists of no less than two independently operating alkaline electrolyzer units. Each alkaline electrolyzer unit can be switched to a running cell or a hot standby cell. The number of running cells and hot standby cells can be adjusted according to the changes in wind and solar power, avoiding thermal stress caused by the need for frequent start-up and shutdown of a single alkaline electrolyzer unit to adapt to power fluctuations. The electrolyzer array is reserved with expansion interfaces, and the number of alkaline electrolyzer units can be increased according to hydrogen production needs.

[0074] The staged waste heat recovery loop is a closed-loop pipeline. The heat transfer medium filled inside the pipe enables heat transfer. A circulation power component on the pipeline provides power for the circulation of the heat transfer medium, allowing it to flow within the loop and carry heat. A temperature monitoring component monitors the temperature at different locations within the loop in real time, providing data for subsequent heat distribution and control. A pressure monitoring component monitors the pressure within the loop to prevent damage due to abnormal pressure. The closed-loop structure reduces heat loss during transmission, providing a stable transmission channel for the recovered waste heat. The phase change material filled inside the phase change storage tank has a phase change temperature that matches the preset standby temperature range of the heat standby tank. When there is excess heat in the staged waste heat recovery loop, the phase change material absorbs and stores heat; when there is insufficient heat in the loop, the phase change material releases the stored heat to maintain the required temperature of the heat standby tank, preventing the heat standby tank from failing to maintain its standby state due to unstable heat supply. Auxiliary and emergency components include... The cooler is connected to the alkali circulation path of the electrolytic cell array. When the alkali temperature in the operating cell is too high and the staged waste heat recovery loop cannot remove the heat in time, the cooler can cool the alkali to ensure the normal electrolysis reaction in the operating cell. The emergency heat exchanger is connected to the staged waste heat recovery loop. When the temperature in the loop rises abnormally and other control methods cannot effectively cool it down, the emergency heat exchanger can cool the heat transfer medium in the loop to prevent the loop and related components from being damaged by high temperature. The flow switching component can control the flow path of the heat transfer medium to realize the switching of the heat transfer path between the staged waste heat recovery loop and the operating cell and the hot standby cell. The uninterruptible power supply can supply power to key components such as the temperature monitoring component, flow switching component, and variable frequency circulating pump when the main power of the system is interrupted, to ensure that the key components can still operate when the power is interrupted, so as to perform necessary temperature control or safe shutdown operations, and prevent the system from being unable to maintain the hot standby state or from being damaged due to the interruption of the main power.

[0075] In step S2, the circulating power component includes a first waste heat recovery heat exchanger connected in parallel on the process alkali cooling path of the operating tank. The first waste heat recovery heat exchanger is connected to the staged waste heat recovery loop. When the reflux alkali from the operating tank flows through the first waste heat recovery heat exchanger, it transfers the process cooling waste heat to the staged waste heat recovery loop.

[0076] A second waste heat recovery heat exchanger is connected in series in the oxygen exhaust path of the oxygen separator. The second waste heat recovery heat exchanger is connected to the staged waste heat recovery loop. When the high-temperature humid oxygen discharged from the oxygen separator flows through the second waste heat recovery heat exchanger, the waste heat of the product gas is transferred to the staged waste heat recovery loop.

[0077] The temperature data corresponding to the process cooling waste heat and product gas waste heat are collected in real time by the temperature monitoring component. The speed of the variable frequency circulating pump is adjusted according to the temperature data collected by the temperature monitoring component, thereby regulating the circulation rate of the heat transfer medium in the staged waste heat recovery loop.

[0078] By adopting the above technical solution, a first waste heat recovery heat exchanger is connected in parallel on the process alkali cooling path of the operating tank, and the first waste heat recovery heat exchanger is connected to the staged waste heat recovery loop. When the return alkali from the operating tank flows through the first waste heat recovery heat exchanger, the process cooling waste heat can be transferred to the staged waste heat recovery loop, which can avoid the direct loss of process cooling waste heat through traditional cooling methods and eliminate the need to rely on external electricity or fuel to provide the heat source required for heating the hot standby tank. A second waste heat recovery heat exchanger is connected in series on the oxygen venting path of the oxygen separator, and the second waste heat recovery heat exchanger is connected to the staged waste heat recovery loop. When the high-temperature humid oxygen discharged from the oxygen separator flows through the second waste heat recovery heat exchanger, the product gas waste heat can be transferred to the staged waste heat recovery loop, which can prevent the product gas waste heat from being directly lost with the oxygen venting, further improving the staged waste heat recovery loop. The heat recovery loop supplements the heat, forming an internal heat recovery channel for the system and reducing the system's dependence on external energy. The temperature monitoring component collects real-time temperature data corresponding to the waste heat from process cooling and product gas. Based on this temperature data, the speed of the variable frequency circulating pump is adjusted. By changing the speed of the variable frequency circulating pump, the circulation rate of the heat transfer medium in the staged waste heat recovery loop can be controlled. When the temperature data shows a large amount of waste heat, the speed is increased to accelerate the circulation of the heat transfer medium, allowing more waste heat to be carried into the loop. When the temperature data shows a small amount of waste heat, the speed is decreased to slow down the circulation of the heat transfer medium, avoiding heat loss due to excessively rapid circulation. This ensures that the staged waste heat recovery loop can efficiently recover heat according to the actual waste heat situation, improving the system's internal energy utilization efficiency and reducing the need for additional energy consumption due to insufficient heat recovery.

[0079] In step S3, when the temperature of the staged waste heat recovery loop is higher than the preset heat standby requirement temperature of the heat standby tank, and the phase change material in the phase change storage tank has not reached the phase change saturation state, the heat transfer medium in the staged waste heat recovery loop is guided to transfer heat to the phase change storage tank, and the phase change material absorbs and stores the heat.

[0080] Determine the first start-up tank in the hot standby tank, prioritize the distribution of heat from the staged waste heat recovery loop to the first start-up tank, maintain the first start-up tank at the target hot standby temperature, and maintain the remaining hot standby tanks at a temperature lower than the target hot standby temperature; when the temperature of the staged waste heat recovery loop meets the target hot standby temperature requirements of all hot standby tanks, adjust the heat distribution ratio to ensure that all hot standby tanks are maintained at the target hot standby temperature.

[0081] By adopting the above technical solution, when the temperature of the staged waste heat recovery loop is higher than the preset backup temperature of the heat standby tank, and the phase change material in the phase change storage tank has not reached phase change saturation, the heat transfer medium in the staged waste heat recovery loop is guided to transfer heat to the phase change storage tank. The phase change material absorbs and stores the heat, which can prevent the staged waste heat recovery loop from abnormally rising in temperature due to excess heat. At the same time, the excess heat is retained in the phase change storage tank in the form of latent heat. When the temperature of the staged waste heat recovery loop is lower than the preset backup temperature, there is no need to rely on external electricity or fuel to supplement the heat required for backup. After determining the first start-up tank in the heat standby tank, the heat in the staged waste heat recovery loop is preferentially allocated to the first start-up tank, so that the first start-up tank is maintained at the target temperature. The system maintains a standby temperature, with the remaining standby tanks kept below the target standby temperature. This ensures that the first-start tank is always at a temperature that meets the requirements for rapid startup, allowing it to be put into operation promptly when wind and solar power recovers. This avoids the problem of insufficient heat distribution caused by all standby tanks needing to maintain the target standby temperature. When the temperature of the staged waste heat recovery loop meets the target standby temperature requirements of all standby tanks, the heat distribution ratio is adjusted to maintain all standby tanks at the target standby temperature. This allows for full utilization of the waste heat recovered by the staged waste heat recovery loop when there is sufficient heat, ensuring that more standby tanks are in a startable state. This improves the system's responsiveness to wind and solar power fluctuations, reduces the idle waste of recovered waste heat, and improves the energy utilization efficiency within the system.

[0082] The dynamic heat transfer between the operating tank and the hot standby tank in step S4 includes the following steps:

[0083] The temperature monitoring component monitors the total temperature of the staged waste heat recovery loop. When the total temperature exceeds the preset temperature threshold, the flow switching component controls the flow switching component to switch the alkali circulation path of the operating tank, so that the return alkali in the operating tank is switched from entering the first waste heat recovery heat exchanger to entering the cooler. The cooler cools down the alkali in the operating tank. The preset temperature threshold is the highest temperature that ensures effective cooling of the alkali in the operating tank.

[0084] When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop has dropped below the preset temperature threshold, the flow control switching component switches the alkaline circulation path of the operating tank again, so that the reflux alkaline solution of the operating tank is reconnected to the first waste heat recovery heat exchanger.

[0085] The flow control switching component connects the alkali circulation path of the hot standby tank to the staged waste heat recovery loop. The heat transfer medium in the staged waste heat recovery loop exchanges heat with the circulating alkali in the hot standby tank through the heat exchange component corresponding to the hot standby tank, which is used to heat the hot standby tank to maintain its temperature within the preset hot standby temperature range or to maintain the temperature.

[0086] By adopting the above technical solution, during the dynamic heat transfer process between the operating tank and the hot standby tank, the thermometer in the temperature monitoring component monitors the total temperature of the staged waste heat recovery loop. When the total temperature exceeds a preset temperature threshold (the highest temperature to ensure effective cooling of the alkali solution in the operating tank), the flow switching component switches the alkali solution circulation path of the operating tank, changing the reflux alkali solution from being connected to the first waste heat recovery heat exchanger to being connected to the cooler. The cooler cools the alkali solution in the operating tank, preventing the alkali solution temperature from exceeding the temperature range required for normal electrolysis and avoiding abnormal electrolysis efficiency due to excessively high alkali solution temperature. When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop has dropped below the preset temperature threshold, the flow switching component switches the alkali solution circulation path of the operating tank again, allowing the reflux alkali solution to reconnect to the first waste heat recovery heat exchanger, thus restoring the operating tank's operation. The transfer of process cooling waste heat to the staged waste heat recovery loop avoids energy waste caused by continuous loss of process cooling waste heat through the cooler, and replenishes the staged waste heat recovery loop with heat to support the heating needs of the subsequent hot standby tank. The flow control switching component connects the alkaline solution circulation path of the hot standby tank to the staged waste heat recovery loop. The heat transfer medium in the staged waste heat recovery loop exchanges heat with the circulating alkaline solution of the hot standby tank through the heat exchange components of the corresponding hot standby tank, heating the hot standby tank to maintain its temperature within the preset hot standby temperature range or to maintain the temperature. During operation, there is no need to rely on external electricity or fuel to provide heat to the hot standby tank, reducing the system's operating energy consumption. At the same time, it keeps the hot standby tank at a temperature that can be quickly put into operation, avoiding the need for a long preheating time before starting due to low temperature. This avoids thermal stress damage caused by frequent start-stop, extends the service life of the hot standby tank, and ensures that the system can respond in a timely manner when wind and solar power recovers, improving the system's adaptability to wind and solar power fluctuations.

[0087] The dynamic scheduling of electrolyzers based on wind and solar power prediction in step S5 includes the following conditions: sufficient or increasing wind and solar power, insufficient or decreasing wind and solar power, and severe insufficient wind and solar power, in which all electrolyzers need to be switched to hot standby mode.

[0088] The operating procedures for wind and solar power supply conditions that are sufficient or increasing are as follows:

[0089] Based on the wind and solar power forecast results, determine the number of new operating slots and the target hot standby slots that need to be switched to operating slots;

[0090] The heat transfer medium in the staged waste heat recovery loop is controlled to transfer heat to the target hot standby tank in a concentrated manner, so that the temperature of the target hot standby tank reaches the start-up temperature. The start-up temperature is the optimal initial temperature when the target hot standby tank is switched to the operating tank, and the start-up temperature is consistent with the preset hot standby temperature range.

[0091] When the actual wind and solar power reaches the starting power requirement of the target hot standby tank, the target hot standby tank is switched to the operating tank. At the same time, the next batch of hot standby tanks to be started is selected, and heat is transferred to the next batch of hot standby tanks to be started through a staged waste heat recovery circuit, so that the next batch of hot standby tanks to be started is maintained in the preset hot standby temperature range.

[0092] By adopting the above technical solution, in situations where wind and solar power is sufficient or increasing, the number of newly added operating cells and the target hot standby cells to be switched to operating cells are determined based on the wind and solar power prediction results. This avoids the power supply and demand mismatch caused by blindly starting electrolyzers without considering power prediction, ensuring that the number of newly added operating cells matches the actual available wind and solar power and preventing energy loss caused by ineffective startup. The heat transfer medium in the staged waste heat recovery loop is controlled to concentrate heat transfer to the target hot standby cells, bringing their temperature to the startup temperature. The startup temperature is the optimal initial temperature when the target hot standby cells are switched to operating cells, and it coincides with the preset hot standby temperature range. Because the startup temperature matches the preset hot standby temperature range, the target hot standby cells do not need to rely on external electricity or fuel to supplement heat to reach the startup temperature. The waste heat recovered solely through the staged waste heat recovery loop is sufficient to meet the temperature requirements, reducing the system's additional energy consumption. When the actual wind and solar power reaches the starting power requirement of the target hot standby tank, the target hot standby tank is switched to the operating tank. Since the target hot standby tank is already at the starting temperature, it can directly enter the electrolysis reaction state, avoiding the slow temperature rise and high energy consumption during the cold start process. At the same time, it avoids the thermal stress generated by the cold start from damaging the core components of the electrolyzer, ensuring the stable operation of the electrolyzer and enabling it to quickly respond to the working conditions of sufficient wind and solar power, allowing the system to enter the corresponding load operating range in a timely manner. After selecting the next batch of hot standby tanks to be started, heat is transferred to them through a staged waste heat recovery loop, so that the next batch of hot standby tanks to be started is maintained in the preset hot standby temperature range. This ensures that when the wind and solar power continues to rise, the next batch of hot standby tanks to be started can quickly switch to the operating tank without long-term reheating, improving the system's response capability to the continuous rise of wind and solar power. At the same time, the waste heat of the staged waste heat recovery loop is continuously utilized to avoid direct loss of waste heat and improve the energy utilization efficiency of the system.

[0093] The operating procedures for insufficient or reduced wind and solar power are as follows:

[0094] Based on the wind and solar power prediction results, determine the operating tanks that need to be deloaded and the corresponding deload slope;

[0095] The current of the tank that needs to be de-loaded is gradually reduced according to the preset de-load slope, so that the load of the tank that needs to be de-loaded gradually decreases.

[0096] When the load of the operating cell that needs to be unloaded drops to the preset minimum technical operating limit, the operating cell is disconnected from the operating circuit of the electrolytic cell array and the electrolytic reaction is stopped.

[0097] The operating tank that is cut out is guided to transfer residual heat to the staged waste heat recovery loop through the corresponding heat exchange components. Once the temperature monitoring component detects that the temperature of the cut-out operating tank has dropped to the preset hot standby temperature range or the maintenance temperature, it is switched to the hot standby tank.

[0098] By adopting the above technical solution, in operation under conditions of insufficient or declining wind and solar power, the operating cells requiring load reduction and the corresponding load reduction slope are determined based on the wind and solar power prediction results. This ensures that the load reduction plan is precisely matched with the declining trend of wind and solar power, avoiding an imbalance between the total operating power of the electrolytic cell array and the actual available wind and solar power due to random load reduction without a basis, and preventing instantaneous power gaps or overload impacts in the system. The current of the operating cells requiring load reduction is gradually reduced according to the preset load reduction slope, causing the load of the operating cells to gradually decrease. This prevents the electrical shock caused by sudden current changes from being transmitted to the core components of the electrolytic cell, such as electrodes and diaphragms, reducing the thermal and mechanical stresses caused by instantaneous load fluctuations and ensuring the structural integrity of the components. When the load of the operating cell requiring load reduction drops to the preset minimum technical operating limit, the operating cell is disconnected from the operating circuit of the electrolytic cell array and the electrolysis reaction is stopped, preventing the operating cell from operating below the minimum technical operating level. Inefficient operation within a limited range prevents increased energy consumption per unit of hydrogen production due to low load, reducing energy waste; the cut-off operating tank is guided to transfer residual heat to the staged waste heat recovery loop through the corresponding heat exchange components, recovering the heat remaining in the cut-off operating tank, such as tank waste heat and alkali waste heat, to the staged waste heat recovery loop, avoiding direct loss of residual heat into the environment, supplementing the heat source for the staged waste heat recovery loop, and reducing dependence on external electricity or fuel during hot standby; once the temperature monitoring component detects that the temperature of the cut-off operating tank has dropped to the preset hot standby temperature range or maintained temperature, it is switched to a hot standby tank, allowing the cut-off operating tank to directly enter the ready-to-start state without undergoing a long preheating process before cold start, avoiding high energy consumption and thermal cycle damage during cold start, extending the service life of the electrolyzer, and ensuring that the tank can be quickly switched back to operating tank when wind and solar power recovers, improving the system's response capability to wind and solar power fluctuations.

[0099] The following procedures are required when wind and solar power are severely insufficient and all electrolytic cells need to be switched to hot standby mode:

[0100] Based on the wind and solar power prediction results, the shutdown sequence and corresponding shutdown load reduction slope of all operating slots are set in advance;

[0101] According to the set shutdown sequence and shutdown load reduction slope, the load of each operating tank is gradually reduced until all operating tanks stop electrolytic reaction;

[0102] After stopping all operating tanks, start the phase change heat storage tank to release the latent heat stored in the phase change material in the tank, and heat the heat transfer medium in the staged waste heat recovery loop.

[0103] The temperature of all hot standby tanks was lowered from the preset hot standby temperature range to the maintenance temperature. At the same time, the operation mode of the variable frequency circulating pump was adjusted, in which the variable frequency circulating pump operated in intermittent low frequency mode.

[0104] Prioritize guiding the heat transfer medium in the staged waste heat recovery loop to transfer heat to the first start-up tank, so that the temperature of the first start-up tank is maintained within the preset hot standby temperature range, while the temperature of the remaining hot standby tanks is maintained at the maintenance temperature.

[0105] By adopting the above technical solution, in operations where wind and solar power are severely insufficient and all electrolyzers need to be switched to hot standby mode, the shutdown sequence and corresponding shutdown load reduction slope of all operating cells can be pre-set based on the wind and solar power prediction results. This allows the shutdown plan to be precisely matched with the wind and solar power attenuation trend, avoiding random shutdowns caused by the lack of a preset sequence and slope, and preventing electrical or thermal stress shocks to the system caused by a sudden drop in the total load of the operating cell array. Gradually reducing the load of each operating cell according to the set shutdown sequence and shutdown load reduction slope until the electrolysis reaction stops can avoid problems such as electrode potential fluctuations and sudden changes in diaphragm stress caused by a sudden drop in load, ensuring the structural integrity of the electrolyzers. After all operating cells are shut down, since the system loses the two major heat sources of process cooling waste heat and product gas waste heat, the phase change heat storage tank is started to release the latent heat stored in the phase change material to heat the heat transfer medium in the staged waste heat recovery loop. This can replace external electricity or fuel to provide heat for hot standby, avoiding reliance on external power or fuel. This approach mitigates the additional energy consumption caused by external energy sources while simultaneously enabling the secondary utilization of recovered waste heat, thus constructing an energy cycle. By lowering the temperature of all standby tanks from the preset standby temperature range to the maintenance temperature, and adjusting the variable frequency circulating pumps to an intermittent low-frequency operation mode, the heat demand of the standby tanks and the energy consumption of the heat transfer medium in the staged waste heat recovery loop can be reduced. This also reduces the heat consumption rate of the phase change thermal storage tank and extends its heating duration. Prioritizing the transfer of heat from the heat transfer medium in the staged waste heat recovery loop to the first-start tank ensures that the first-start tank remains within the preset standby temperature range, while the remaining standby tanks remain at the maintenance temperature. This ensures that when wind and solar power recover, the first-start tank can quickly switch to operation without prolonged preheating, shortening the system's response time for hydrogen production recovery. Furthermore, in situations with limited heat, priority is given to ensuring core startup needs, avoiding the problem of uneven heat distribution preventing all standby tanks from starting quickly, and improving the system's recovery capability under extreme conditions.

[0106] Step S5 also includes the periodic switching between the running slot and the hot standby slot. The steps are as follows:

[0107] First, set the continuous operating time threshold for the alkaline electrolysis cell unit. When the continuous operating time of any operating cell reaches the continuous operating time threshold, or when the system enters the planned maintenance phase, determine the target hot standby cell that needs to be switched to the operating cell.

[0108] Within a preset time before switching, the preheating program of the target hot standby tank is started, and heat is transferred to the target hot standby tank through a staged waste heat recovery loop so that the temperature of the target hot standby tank reaches the start-up temperature.

[0109] Gradually reduce the load on the standby operating tank while increasing the load on the target hot standby tank until the load on the standby operating tank drops to zero and the load on the target hot standby tank reaches the rated operating load, thus completing the switch between the operating tank and the hot standby tank.

[0110] After the standby tank stops operating, residual heat is recovered through the corresponding heat exchange components. Once the temperature monitoring components detect that the temperature has dropped to the preset hot standby temperature range or maintained temperature, it switches to hot standby tank.

[0111] By adopting the above technical solution, in the periodic switching operation between the operating tank and the hot standby tank, a continuous operating time threshold for the alkaline electrolytic cell unit is set. When the continuous operating time of any operating tank reaches this threshold or the system enters the planned maintenance phase, the target hot standby tank that needs to be switched to the operating tank is determined. This can avoid electrode damage caused by long-term continuous operation of a single operating tank by balancing the operating time of each alkaline electrolytic cell unit. Before the switch, the preheating program of the target hot standby tank is started within a preset time. Heat is transferred to the target hot standby tank through a staged waste heat recovery loop to bring the temperature of the target hot standby tank to the start-up temperature. This can provide heat for the target hot standby tank without relying on external electricity or fuel. The temperature requirement can be met by only the waste heat recovered by the staged waste heat recovery loop, reducing the extra energy consumption in the preheating stage, and at the same time, ensuring that the target hot standby tank is in a temperature state that meets the start-up requirements in advance. The load of the operating tank to be shut down is gradually reduced, while the load of the target hot standby tank is increased. The load transition continues until the load of the standby tank drops to zero and the load of the target hot standby tank reaches its rated operating load to complete the switchover. This load transition method avoids fluctuations in the total system load caused by the sudden shutdown of the standby tank and the sudden full-load operation of the target hot standby tank, ensuring continuous and stable operation of the system during the switchover process and preventing the impact of sudden load changes on the efficiency of the electrolysis reaction. After the standby tank stops, its residual heat is recovered through the corresponding heat exchange components. Once the temperature monitoring components detect that its temperature has dropped to the preset hot standby temperature range or the maintenance temperature, it switches to the hot standby tank. This can recover the residual heat remaining in the standby tank to the staged waste heat recovery loop, avoiding direct loss of residual heat and supplementing the heat source for the staged waste heat recovery loop. At the same time, it allows the standby tank to directly enter the hot standby state without having to undergo a long preheating period before cold start, reducing energy consumption and thermal stress damage during cold start and extending the service life of the alkaline electrolytic cell unit.

[0112] Activating the security redundancy protection mechanism in step S6 includes the following steps:

[0113] A temperature safety valve is installed on the staged waste heat recovery loop. When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop exceeds the safe temperature threshold and the phase change material in the phase change heat storage tank has reached the phase change saturation state, the temperature safety valve is opened and the emergency heat exchanger is started to cool the heat transfer medium in the staged waste heat recovery loop through the emergency heat exchanger.

[0114] When the main power supply of the system fails, the uninterruptible power supply is started to supply power to the temperature monitoring component, the flow switching component and the variable frequency circulating pump.

[0115] If there is a running slot in the system before the main power supply fails, the running slot is controlled to reduce the load to the shutdown state according to the preset load reduction slope, and then switched to the hot standby slot.

[0116] If the system is already in hot standby mode before the main power supply fails, maintain the intermittent low-frequency operation mode of the variable frequency circulating pump.

[0117] By adopting the above technical solution and activating the safety redundancy protection mechanism, a temperature safety valve is installed on the staged waste heat recovery loop. When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop exceeds the safe temperature threshold, and the phase change material in the phase change storage tank has reached phase change saturation, the temperature safety valve is opened and the emergency heat exchanger is activated. The emergency heat exchanger cools the heat transfer medium in the staged waste heat recovery loop, preventing overheating damage to components such as pipes and heat exchangers due to continuous temperature increases. When the system's main power supply fails, the uninterruptible power supply (UPS) is activated to power the temperature monitoring component, flow switching component, and variable frequency circulating pump, ensuring basic operation is maintained during the main power outage and preventing the inability to monitor loop temperature or switch heat transfer paths due to component shutdown. This prevents the system from falling into an uncontrolled state. If the system has an operating tank before the main power fails, the operating tank is controlled to reduce the load to the shutdown state according to the preset load reduction slope and then switch to a hot standby tank. This avoids the sudden load drop and thermal stress impact caused by the sudden power failure and shutdown of the operating tank, reduces damage to components such as electrodes and diaphragms caused by instantaneous state changes, and extends the service life of the operating tank. If the system is already in a hot standby state before the main power fails, the intermittent low-frequency operation mode of the variable frequency circulating pump is maintained. This ensures that the heat transfer medium in the staged waste heat recovery loop can still circulate slowly, keeping the temperature of the hot standby tank within the preset hot standby temperature range or maintaining the temperature. This avoids the hot standby tank from rapidly dropping in temperature due to circulation stagnation. When the wind and solar power recovers, it can quickly switch to an operating tank without long-term reheating, while reducing the additional energy consumption generated by the continuous high-frequency operation of the variable frequency circulating pump.

[0118] 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. A method for off-grid alkaline electrolysis full-heat backup based on deep integrated recovery of multi-source waste heat, characterized in that, Includes the following steps: S1. Constructing a framework, the framework including an electrolytic cell array, a staged waste heat recovery loop, a phase change thermal storage tank, and auxiliary and emergency components; S2. Synchronous capture system for multi-source waste heat: Start the circulating power component of the staged waste heat recovery loop to synchronously collect the process cooling waste heat and product gas waste heat generated during the operation of the electrolyzer array through the staged waste heat recovery loop; S3. Heat storage and tiered distribution: When there is excess heat in the staged waste heat recovery loop, the excess heat is stored in the phase change heat storage tank. At the same time, the heat in the staged waste heat recovery loop is distributed to each heat reserve tank according to the priority of the heat reserve tank. S4. Dynamically execute heat transfer between the operating tank and the hot standby tank: By controlling the flow switching component, regulate the heat transfer path between the staged waste heat recovery loop and the operating tank and the hot standby tank, realize the heat output from the operating tank to the staged waste heat recovery loop, and the heat input from the staged waste heat recovery loop to the hot standby tank. S5. Dynamic scheduling of electrolyzers based on wind and solar power prediction: Adjust the number and operating status of operating cells and hot standby cells in the electrolyzer array according to the wind and solar power prediction results. S6. Activate the safety redundancy protection mechanism, monitor the operating parameters of the staged waste heat recovery circuit and the system power supply status, and perform emergency handling operations when parameters are abnormal or power supply is interrupted.

2. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 1, characterized in that, In step S1, the electrolytic cell array consists of no less than two independently operating alkaline electrolytic cell units. Each alkaline electrolytic cell unit is switchable between a running cell and a hot standby cell, and the electrolytic cell array has reserved expansion interfaces. The staged waste heat recovery loop is a closed-loop circulation pipeline filled with a heat-conducting medium. The staged waste heat recovery loop is equipped with a circulation power component, a temperature monitoring component, and a pressure monitoring component. The circulation power component is a variable frequency circulation pump, and the temperature monitoring component includes at least five thermometers. The phase change heat storage tank is filled with phase change material, and the phase change temperature of the phase change material matches the preset hot standby temperature range of the hot standby tank. The auxiliary and emergency components include a cooler, an emergency heat exchanger, a flow switching component, and an uninterruptible power supply. The flow switching component consists of at least two three-way valves. The cooler is connected to the alkaline solution circulation path of the electrolytic cell array, and the emergency heat exchanger is connected to the staged waste heat recovery loop.

3. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 1, characterized in that, In step S2, the circulating power component includes a first waste heat recovery heat exchanger connected in parallel on the process alkali cooling path of the operating tank. The first waste heat recovery heat exchanger is connected to the staged waste heat recovery loop. When the reflux alkali from the operating tank flows through the first waste heat recovery heat exchanger, it transfers the process cooling waste heat to the staged waste heat recovery loop. A second waste heat recovery heat exchanger is connected in series in the oxygen exhaust path of the oxygen separator. The second waste heat recovery heat exchanger is connected to the staged waste heat recovery circuit. When the high-temperature humid oxygen discharged from the oxygen separator flows through the second waste heat recovery heat exchanger, the waste heat of the product gas is transferred to the staged waste heat recovery circuit. The temperature data corresponding to the process cooling waste heat and product gas waste heat are collected in real time by the temperature monitoring component. The speed of the variable frequency circulating pump is adjusted according to the temperature data collected by the temperature monitoring component, thereby regulating the circulation rate of the heat transfer medium in the staged waste heat recovery loop.

4. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 1, characterized in that, In step S3, when the temperature of the staged waste heat recovery loop is higher than the preset heat standby requirement temperature of the heat standby tank, and the phase change material in the phase change storage tank has not reached the phase change saturation state, the heat transfer medium in the staged waste heat recovery loop is guided to transfer heat to the phase change storage tank, and the phase change material absorbs and stores the heat. Determine the first start-up tank in the hot standby tank, prioritize the distribution of heat from the staged waste heat recovery loop to the first start-up tank, maintain the first start-up tank at the target hot standby temperature, and maintain the remaining hot standby tanks at a temperature lower than the target hot standby temperature; when the temperature of the staged waste heat recovery loop meets the target hot standby temperature requirements of all hot standby tanks, adjust the heat distribution ratio to ensure that all hot standby tanks are maintained at the target hot standby temperature.

5. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 1, characterized in that, The dynamic heat transfer between the operating tank and the hot standby tank in step S4 includes the following steps: The temperature monitoring component monitors the total temperature of the staged waste heat recovery loop. When the total temperature exceeds the preset temperature threshold, the flow switching component controls the flow switching component to switch the alkali circulation path of the operating tank, so that the return alkali in the operating tank is switched from entering the first waste heat recovery heat exchanger to entering the cooler. The cooler cools down the alkali in the operating tank. The preset temperature threshold is the highest temperature that ensures effective cooling of the alkali in the operating tank. When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop has dropped below the preset temperature threshold, the flow control switching component switches the alkaline circulation path of the operating tank again, so that the reflux alkaline solution of the operating tank is reconnected to the first waste heat recovery heat exchanger. The flow control switching component connects the alkali circulation path of the hot standby tank to the staged waste heat recovery loop. The heat transfer medium in the staged waste heat recovery loop exchanges heat with the circulating alkali in the hot standby tank through the heat exchange component corresponding to the hot standby tank, which is used to heat the hot standby tank to maintain its temperature within the preset hot standby temperature range or to maintain the temperature.

6. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 1, characterized in that, The dynamic scheduling of electrolyzers based on wind and solar power prediction in step S5 includes the following conditions: sufficient or increasing wind and solar power, insufficient or decreasing wind and solar power, and severe insufficient wind and solar power, in which all electrolyzers need to be switched to hot standby mode. The operating procedures for wind and solar power supply conditions that are sufficient or increasing are as follows: Based on the wind and solar power forecast results, determine the number of new operating slots and the target hot standby slots that need to be switched to operating slots; The heat transfer medium in the staged waste heat recovery loop is controlled to transfer heat to the target hot standby tank in a concentrated manner, so that the temperature of the target hot standby tank reaches the start-up temperature. The start-up temperature is the optimal initial temperature when the target hot standby tank is switched to the operating tank, and the start-up temperature is consistent with the preset hot standby temperature range. When the actual wind and solar power reaches the starting power requirement of the target hot standby tank, the target hot standby tank is switched to the operating tank. At the same time, the next batch of hot standby tanks to be started is selected, and heat is transferred to the next batch of hot standby tanks to be started through a staged waste heat recovery circuit, so that the next batch of hot standby tanks to be started is maintained in the preset hot standby temperature range.

7. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 6, characterized in that, The operating procedures for insufficient or reduced wind and solar power are as follows: Based on the wind and solar power prediction results, determine the operating tanks that need to be deloaded and the corresponding deload slope; The current of the tank that needs to be de-loaded is gradually reduced according to the preset de-load slope, so that the load of the tank that needs to be de-loaded gradually decreases. When the load of the operating cell that needs to be unloaded drops to the preset minimum technical operating limit, the operating cell is disconnected from the operating circuit of the electrolytic cell array and the electrolytic reaction is stopped. The operating tank that is cut out is guided to transfer residual heat to the staged waste heat recovery loop through the corresponding heat exchange components. Once the temperature monitoring component detects that the temperature of the cut-out operating tank has dropped to the preset hot standby temperature range or the maintenance temperature, it is switched to the hot standby tank.

8. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 6, characterized in that, The following procedures are required when wind and solar power are severely insufficient and all electrolytic cells need to be switched to hot standby mode: Based on the wind and solar power prediction results, the shutdown sequence and corresponding shutdown load reduction slope of all operating slots are set in advance; According to the set shutdown sequence and shutdown load reduction slope, the load of each operating tank is gradually reduced until all operating tanks stop electrolytic reaction; After stopping all operating tanks, start the phase change heat storage tank to release the latent heat stored in the phase change material in the tank, and heat the heat transfer medium in the staged waste heat recovery loop. The temperature of all hot standby tanks was lowered from the preset hot standby temperature range to the maintenance temperature. At the same time, the operation mode of the variable frequency circulating pump was adjusted, in which the variable frequency circulating pump operated in intermittent low frequency mode. Prioritize guiding the heat transfer medium in the staged waste heat recovery loop to transfer heat to the first start-up tank, so that the temperature of the first start-up tank is maintained within the preset hot standby temperature range, while the temperature of the remaining hot standby tanks is maintained at the maintenance temperature.

9. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 1, characterized in that, Step S5 also includes the periodic switching operation between the operating slot and the hot standby slot, and the operation steps are as follows: First, set the continuous operating time threshold for the alkaline electrolysis cell unit. When the continuous operating time of any operating cell reaches the continuous operating time threshold, or when the system enters the planned maintenance phase, determine the target hot standby cell that needs to be switched to the operating cell. Within a preset time before switching, the preheating program of the target hot standby tank is started, and heat is transferred to the target hot standby tank through a staged waste heat recovery loop so that the temperature of the target hot standby tank reaches the start-up temperature. Gradually reduce the load on the standby operating tank while increasing the load on the target hot standby tank until the load on the standby operating tank drops to zero and the load on the target hot standby tank reaches the rated operating load, thus completing the switch between the operating tank and the hot standby tank. After the standby tank stops operating, residual heat is recovered through the corresponding heat exchange components. Once the temperature monitoring components detect that the temperature has dropped to the preset hot standby temperature range or maintained temperature, it switches to hot standby tank.

10. The off-grid alkaline electrolysis full-heat backup method based on deep integrated recovery of multi-source waste heat according to claim 1, characterized in that, The activation of the security redundancy protection mechanism in step S6 includes the following steps: A temperature safety valve is installed on the staged waste heat recovery loop. When the thermometer in the temperature monitoring component detects that the total temperature of the staged waste heat recovery loop exceeds the safe temperature threshold and the phase change material in the phase change heat storage tank has reached the phase change saturation state, the temperature safety valve is opened and the emergency heat exchanger is started to cool the heat transfer medium in the staged waste heat recovery loop through the emergency heat exchanger. When the main power supply of the system fails, the uninterruptible power supply is started to supply power to the temperature monitoring components, flow switching components and variable frequency circulating pump. If there is a running slot in the system before the main power supply fails, the running slot is controlled to reduce the load to the shutdown state according to the preset load reduction slope, and then switched to the hot standby slot. If the system is already in hot standby mode before the main power supply fails, maintain the intermittent low-frequency operation mode of the variable frequency circulating pump.

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