Molten salt heat supply type methanol reforming fuel cell energy storage device and method

Abstract

The invention discloses a molten salt heat supply type methanol reforming fuel cell energy storage device and method, and belongs to the technical field of comprehensive energy storage. The fused salt energy storage system adopts composite phase change heat storage fused salt, so that the heat storage density and the heat stability are obviously improved; the catalytic reformer adopts a sawtooth spiral tube bundle type structure to strengthen heat transfer; the fuel cell adopts the bionic fractal flow channel bipolar plate to improve the gas distribution uniformity and the power generation efficiency. According to the invention, stable and zero-carbon-emission reaction heat is provided for the methanol reforming hydrogen production system by using green heat energy stored by the fused salt energy storage system; high-temperature tail gas and reaction waste heat generated by the fuel cell power generation system are recycled through the waste heat recycling system and fed back to the molten salt system or used for catalytic reforming and steam generation, and a heat closed loop in the system is constructed. The method comprises the following steps: heating the fused salt by using cheap energy to store energy, thermally driving methanol reforming to produce hydrogen by using the fused salt, and further generating power through the fuel cell.

Description

Technical Field

[0001] This invention belongs to the field of integrated energy storage technology, specifically relating to a molten salt heating type methanol reforming fuel cell energy storage device and method. Background Technology

[0002] With the rapid development of renewable energy sources such as wind and solar power, their inherent intermittency and volatility pose a significant challenge to the stable operation of power grids. Therefore, developing long-duration, high-efficiency energy storage technologies has become an urgent need in the energy sector.

[0003] Among existing energy storage technologies, pumped hydro storage and compressed air storage are limited by geographical conditions; lithium-ion batteries are costly, resource-constrained, and unsuitable for ultra-long-term energy storage. Hydrogen energy is considered an ideal energy storage medium, but hydrogen faces safety and cost bottlenecks in storage and transportation.

[0004] Methanol, as a liquid hydrogen carrier, boasts advantages such as high energy density, safe and convenient storage and transportation, and good infrastructure compatibility. Producing hydrogen through methanol steam reforming and then coupling it with fuel cells for power generation is a very promising technological path. However, traditional methanol reforming reactions require continuous external heating, typically achieved by burning a portion of the methanol or natural gas. This not only reduces system efficiency but also generates carbon emissions.

[0005] On the other hand, molten salt thermal energy storage technology is widely used in the field of concentrated solar power (CSP) due to its high thermal density, wide operating temperature range, and low cost. However, there is currently no mature solution to innovatively couple mature molten salt thermal energy storage technology with chemical energy storage and fuel cell technology to build an efficient, clean, and flexible energy storage system. Summary of the Invention

[0006] The primary objective of this invention is to overcome the inherent defects of existing methanol reforming hydrogen production technology, which relies on combustion heating and leads to limited carbon emissions and system efficiency, and to provide a new zero-carbon emission heating method based on molten salt thermal storage.

[0007] Another objective of this invention is to construct a highly integrated, multi-energy-flow coupled energy storage system that, through internal energy cascade utilization and closed-loop management, enables efficient, stable, and large-scale storage and scheduling of fluctuating renewable energy sources, and outputs high-quality electrical and thermal energy.

[0008] The technical solution adopted in this invention is: A molten salt heating type methanol reforming fuel cell energy storage device, including Molten salt energy storage systems are used to receive and store electrical energy or thermal energy converted from industrial waste heat. The methanol reforming hydrogen production system uses a molten salt energy storage system as a heat source for the methanol reforming reaction. The fuel cell power generation system is connected to the methanol reforming hydrogen production system, receiving hydrogen-rich reformed gas for power generation. A waste heat recovery system is used to transfer the recovered heat to the molten salt energy storage system and / or the methanol reforming hydrogen production system.

[0009] Furthermore, the molten salt energy storage system includes a molten salt heat exchanger, a low-temperature molten salt tank, a molten salt pump, and a high-temperature molten salt tank, which are connected in sequence through a molten salt heat release circuit, as well as an external heat source input device to provide heat to the molten salt in the low-temperature molten salt tank. Furthermore, the molten salt used in the molten salt energy storage system is a composite phase change thermal storage molten salt, which is composed of a matrix molten salt and uniformly dispersed nanofunctional materials therein. The matrix molten salt is a mixture of sodium nitrate and potassium nitrate. The nanofunctional materials include hydrophilic fumed silica nanoparticles and carbon nanotubes.

[0010] Furthermore, the methanol reforming hydrogen production system includes a methanol-water solution storage tank, a transfer pump, a steam generator, and a catalytic reformer connected in sequence; the shell-side flow channel inlet and outlet of the catalytic reformer are connected to the low-temperature side pipeline of the molten salt exothermic heat exchanger.

[0011] Furthermore, the catalytic reformer integrates a serrated tube bundle arranged in a spiral twist, which is inclined and wound from top to bottom with a fixed pitch to form a spiral tube bundle bed structure. The catalytic reformer is equipped with several arc-shaped support plates, which are evenly distributed at different heights to support and constrain the spiral tube bundle, ensuring that the fluid flows along the spiral path in the shell side of the catalytic reformer.

[0012] Furthermore, the fuel cell power generation system includes a fuel cell stack, the anode inlet of the fuel cell stack is connected to the gas production outlet of the catalytic reformer, and the cathode inlet of the fuel cell stack is connected to an air supply device.

[0013] Furthermore, the anode and cathode bipolar plates of the fuel cell stack both adopt a biomimetic fractal flow channel design that mimics the veins of plant leaves. This flow channel structure consists of a primary main flow channel and a secondary branch flow channel, with a smooth transition between each flow channel.

[0014] Furthermore, the waste heat recovery system includes: a tail gas burner connected to the anode tail gas outlet of the fuel cell stack, and a waste heat recovery pipeline installed at the flue gas outlet end of the tail gas burner. The waste heat recovery pipeline includes the following units: Molten salt reheating: High-temperature flue gas flows through a reheating heat exchanger, the cold side of which is connected in series in the molten salt return pipeline from the low-temperature molten salt tank to the external heat source input equipment or the high-temperature molten salt tank; Catalytic reforming: The medium-temperature flue gas flows through a supplementary heat exchanger, the cold side of which is connected in series in the pipeline of the reforming reactor.

[0015] Steam generation: Low-temperature flue gas flows through a supplementary heat exchanger, the cold side of which is connected in series with the pipeline of the steam generator.

[0016] A method for energy storage and power supply of a molten salt heated methanol reforming fuel cell energy storage device includes the following steps: S1. Energy storage stage: Utilizing off-peak electricity from the power grid, abandoned renewable energy, or industrial waste heat, the molten salt flowing out of the low-temperature molten salt tank is heated through the external heat source input device, and the heated high-temperature molten salt is stored in the high-temperature molten salt tank; S2. Power generation stage: S21. Driving high-temperature molten salt through a molten salt exothermic heat exchanger to provide reaction heat for the catalytic reformer; S22. Methanol and water are fed into the steam generator and the catalytic reformer, and a reforming reaction occurs under molten salt heating to generate reformed gas. S23. The high-purity hydrogen gas is delivered to the anode of the fuel cell stack to carry out an electrochemical reaction and generate electrical energy; S24. The anode tail gas discharged from the fuel cell stack is fed into the tail gas burner for combustion, and the generated high-temperature flue gas is fed into the waste heat recovery pipeline to recover its heat for heating the reflux molten salt and / or for catalytic reforming and steam generation.

[0017] Furthermore, during the power generation stage, the reforming reaction temperature is controlled between 200°C and 600°C by dynamically adjusting the flow rate of molten salt through the catalytic reformer; and the heat recovered by the waste heat recovery system is dynamically distributed.

[0018] Compared with the prior art, the present invention has the following advantages: 1. Enhanced Synergistic Performance of Materials and Components: The composite thermal storage molten salt developed in this invention uses nano-SiO2 to suppress overcooling and enhance stability, and utilizes carbon nanotubes to construct a high thermal conductivity network, maintaining good fluidity within the 290℃-565℃ range. Particularly in the 400℃-500℃ range, micro-regional phase transitions induced by nanomaterials achieve synergistic thermal storage of sensible and latent heat, increasing the volumetric thermal storage density by 15%-25% compared to conventional molten salts. This not only reduces tank volume and cost but also provides a stable temperature basis for subsequent reforming reactions. The catalytic reformer adopts a serrated helical tube bundle structure. The secondary flow generated by its curved channels significantly enhances fluid mixing and heat transfer, increasing the heat transfer coefficient by 1.5-3 times. The shell-side helical flow reduces dead zones, achieving a more uniform temperature field and mass transfer effect, thereby improving methanol conversion and suppressing side reactions such as CO. The fuel cell employs a fractal flow channel structure, ensuring extremely uniform distribution of fuel and oxidant throughout the entire electrode active area, while efficiently discharging reaction products, reducing concentration polarization, resulting in more stable voltage output and higher power generation efficiency. Through multi-level optimization of materials and structure, the entire system achieves efficient synergy and performance improvement in energy storage, reaction, and power generation.

[0019] 2. Zero-carbon emission, high-efficiency chemical process: Traditional methanol reforming requires the combustion of some fuel for heating, inevitably generating carbon emissions. This invention utilizes green electricity or waste heat stored in molten salt as a heat source, fundamentally cutting off direct carbon emissions from the reforming process and providing stable, zero-carbon emission reaction heat for the methanol reforming hydrogen production system. Molten salt heating avoids the problems of localized overheating and low thermal efficiency that may occur with combustion heating, keeping the reforming reaction always within the optimal catalytic temperature range. This improves methanol conversion and hydrogen production efficiency, and also extends catalyst life.

[0020] 3. The system achieves tiered energy utilization and internal circulation: It realizes tiered energy utilization through a process of "high-temperature molten salt (565℃) → medium-temperature reforming (250-400℃) → exhaust gas combustion (600-800℃) → waste heat recovery," ensuring that heat energy of different grades is used to its fullest potential and significantly reducing the ineffective devaluation of energy quality. By recovering the combustion heat of the fuel cell stack anode exhaust gas, it provides "reheating" for the molten salt system, catalytic reforming, and steam generation, forming a highly efficient internal energy cycle and significantly reducing the dependence on external high-quality heat energy during the power generation stage.

[0021] 4. Excellent energy resilience, flexibility, and economy: The system can flexibly accommodate various heat sources such as off-peak electricity / abandoned electricity from the grid and industrial waste heat. This multi-source coupling characteristic not only reduces operating costs but also makes the system more resilient and able to withstand fluctuations in a single energy source. This invention also cleverly combines large-capacity, long-duration, low-cost molten salt thermal energy storage with high-energy-density, easily transportable methanol-hydrogen storage. The synergy between thermal energy storage and chemical hydrogen storage leverages the advantages of large-scale, low-cost molten salt thermal energy storage while circumventing the safety and cost bottlenecks of large-scale hydrogen storage and transportation, providing a highly commercially viable technical route for achieving long-term energy storage at the weekly or even monthly level.

[0022] 5. Provides excellent dual service capabilities to the power grid: The device of this invention is both a stable power source and a flexible load. During peak electricity demand, the device can act as a stable and adjustable distributed generator, supplying high-quality power to the grid. During off-peak hours or when renewable energy is abundant, it transforms into a large "thermal battery" load, absorbing abandoned power and helping the grid to smooth out peak demand and fill valleys.

[0023] 6. Diverse application scenarios: The device of this invention can not only serve as the core of an independent power plant or microgrid, but also be widely used in industrial parks (to absorb off-peak electricity and its own waste heat to achieve combined heat and power), remote areas (to achieve energy self-sufficiency by utilizing wind and solar energy storage), and as a backup power source for data centers, communication base stations and other high-reliability applications. The market application prospects are extremely broad. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the device of the present invention; Figure 2 This is a schematic diagram of the catalytic reformer structure of the present invention; Figure 3 This is a front view of the catalytic reformer of the present invention; Figure 4 This is a cross-sectional view of the catalytic reformer of the present invention; Figure 5 This is a top view of the catalytic reformer of the present invention; Figure 6 This is a cross-sectional view of the serrated tube of the present invention; Figure 7 This is a schematic diagram of the sawtooth tube structure of the present invention; Figure 8 This is a schematic diagram of the fuel cell structure of the present invention; Figure 9 This is a schematic diagram of the biomimetic fractal flow channel of the fuel cell of the present invention; The components include: 1. High-temperature molten salt tank; 2. Low-temperature molten salt tank; 3. Molten salt pump; 4. Molten salt heat exchanger; 7. Methanol-water solution storage tank; 8. Transfer pump; 9. Steam generator; 10. Catalytic reformer; 11. Fuel cell stack; 12. Air supply device; 13. Exhaust gas burner. Detailed Implementation

[0025] To better understand the purpose, structure, and function of this invention, the invention will be described in further detail below with reference to the accompanying drawings.

[0026] This invention relates to an energy storage method and corresponding apparatus that utilizes molten salt as a heat source / heat storage medium to catalytically reform methanol for supplying hydrogen to fuel cells.

[0027] like Figure 1 As shown, a molten salt heating type methanol reforming fuel cell energy storage device includes... Molten salt energy storage systems are used to receive and store electrical energy or thermal energy converted from industrial waste heat. They employ composite phase change thermal storage molten salt, which significantly improves thermal storage density and thermal stability. The methanol reforming hydrogen production system uses a molten salt energy storage system as a heat source for the methanol reforming reaction and adopts a serrated spiral tube bundle structure to enhance heat transfer. The fuel cell uses a biomimetic fractal flow channel bipolar plate to improve gas distribution uniformity and power generation efficiency.

[0028] The fuel cell power generation system is connected to the methanol reforming hydrogen production system, receiving hydrogen-rich reformed gas for power generation; and utilizes the green thermal energy stored in the molten salt energy storage system to provide stable, zero-carbon emission reaction heat for the methanol reforming hydrogen production system.

[0029] A waste heat recovery system is used to transfer the recovered heat to the molten salt energy storage system and / or the methanol reforming hydrogen production system. By recovering the high-temperature exhaust gas and reaction waste heat generated by the fuel cell power generation system and feeding it back to the molten salt system or using it for catalytic reforming and steam generation, a closed-loop heat system is constructed within the system.

[0030] like Figure 1 As shown, the molten salt energy storage system includes a molten salt heat exchanger 4, a low-temperature molten salt tank 2, a molten salt pump 3, and a high-temperature molten salt tank 1, which are connected in sequence through a molten salt heat release circuit, as well as at least one external heat source input device to provide heat to the molten salt in the low-temperature molten salt tank 2. The external heat source input device includes an electric heater and / or an external heat exchanger connected to an external industrial waste heat source.

[0031] The electric heating equipment is installed in the pipeline between the low-temperature molten salt tank 2 and the high-temperature molten salt tank 1.

[0032] The molten salt used in the molten salt energy storage system is a composite phase change thermal storage molten salt, which consists of a matrix molten salt and uniformly dispersed nanomaterials. The matrix molten salt is a mixture of sodium nitrate and potassium nitrate; the nanomaterials include hydrophilic fumed silica nanoparticles and carbon nanotubes. This composite phase change thermal storage molten salt achieves synergistic thermal storage of sensible and latent heat through the micro-regional phase change effect induced by nanoparticles. Compared with traditional solar salt, its volumetric thermal storage density is increased by about 15%-25%, and the output temperature is more stable.

[0033] like Figure 1 As shown, the methanol reforming hydrogen production system includes a methanol-water solution storage tank 7, a transfer pump 8, a steam generator 9, and a gas inlet of a catalytic reformer 10 connected in sequence. like Figures 2-7 As shown, the catalytic reformer 10 is integrated with a serrated tube bundle arranged in a spiral twist, which is inclined and wound from top to bottom with a fixed pitch to form a spiral tube bundle bed structure. The catalytic reformer 10 is provided with several arc-shaped support plates, which are evenly distributed at different heights to support and constrain the spiral tube bundle, ensuring that the fluid flows along the spiral path in the shell side of the catalytic reformer 10.

[0034] The serrated tube bundle is a spiral reaction tube with serrated undulations on the outer wall. Compared to a smooth straight tube structure, this serrated spiral tube generates secondary flow due to the curved channels, which significantly enhances fluid mixing and continuously disturbs the boundary layer. Furthermore, the increased surface area and turbulence effect of the serrated outer surface improve the heat transfer coefficient between the inside and outside of the tube by 1.5-3 times. Simultaneously, it forces a spiral flow in the shell side, reducing dead zones, thus achieving higher heat transfer efficiency and a more uniform temperature field. For methanol reforming, this uniform temperature and enhanced mass transfer improve heat transfer and diffusion around the catalyst, reduce external diffusion limitations, avoid local overheating or cold spots, increase methanol conversion, and suppress side reactions such as CO formation. This shell-side flow channel is connected to the outlet and inlet of the molten salt exothermic heat exchanger 4 via piping, ensuring that the molten salt flowing out of the high-temperature molten salt tank 1 provides the full heat required for the internal catalytic reforming reaction.

[0035] like Figure 1 As shown, the fuel cell power generation system includes at least one fuel cell stack 11. The anode inlet of the fuel cell stack 11 is connected to the gas production outlet of the catalytic reformer 10 through a reforming gas delivery pipeline to receive hydrogen-rich reforming gas. The fuel cell stack 11 may be a solid oxide fuel cell (SOFC) stack.

[0036] The cathode air inlet of the fuel cell stack 11 is connected to the air supply device 12.

[0037] The air supply unit 12 may be a blower.

[0038] like Figure 8 , Figure 9 As shown, the anode and cathode bipolar plates of the fuel cell stack 11 both adopt a biomimetic fractal flow channel design that mimics the veins of plant leaves. This flow channel structure consists of a primary main channel and a secondary branch channel, with smooth transitions between each level, following the laws of natural fractals. This design ensures that the reactant gas can uniformly cover the entire electrode active area with low flow resistance, significantly reducing concentration polarization and improving current density and power generation efficiency.

[0039] like Figure 1 As shown, the waste heat recovery system includes: a tail gas burner 13 connected to the anode tail gas outlet of the fuel cell stack 11, and a waste heat recovery pipeline installed at the flue gas outlet of the tail gas burner 13, for transferring the recovered heat to the molten salt energy storage system and / or the methanol reforming hydrogen production system. The waste heat recovery pipeline includes the following units: Molten salt reheating: High-temperature flue gas flows through the reheating heat exchanger, and its cold side is connected in series with the electric heater from the low-temperature molten salt tank 2 to the external heat source input equipment or the molten salt return pipeline of the high-temperature molten salt tank 1. Catalytic reforming: The medium-temperature flue gas flows through a supplementary heat exchanger, the cold side of which is connected in series in the pipeline of the reforming reactor 10.

[0040] Steam generation: Low-temperature flue gas flows through a supplementary heat exchanger, the cold side of which is connected in series with the pipeline of steam generator 9.

[0041] A method for energy storage and power supply of a molten salt heated methanol reforming fuel cell energy storage device includes the following steps: S1. Energy storage stage: When there is a power surplus or industrial waste heat, the molten salt flowing out of the low-temperature molten salt tank 2 is heated by the external heat source input device using off-peak electricity from the power grid, abandoned renewable energy, or industrial waste heat, and the heated high-temperature molten salt is stored in the high-temperature molten salt tank 1. S2. High-efficiency power generation and internal circulation stage: S21. Molten salt heating reforming: When power is required, start the molten salt pump 3 to transport high-temperature molten salt from the high-temperature molten salt tank 1 to the molten salt heat exchanger 4, and then provide heat to the reforming reactor 10 and the steam generator 9 in turn. S22. Continuous Hydrogen Production: Simultaneously, a methanol-water mixture is pumped to a steam generator 9 via a transfer pump 8 and then injected into a reforming reactor 10. Under the action of a catalyst, a steam reforming reaction is carried out using the heat provided by the molten salt, continuously producing hydrogen-rich reformed gas; S23. Fuel cell power generation: The reformed gas generated is purified and then delivered to the anode of the fuel cell stack 11; at the same time, air is introduced into the cathode to carry out an electrochemical reaction to generate direct current. S24. Internal Waste Heat Recovery: This step is performed concurrently with S2.3 and includes two levels of recovery: a. The high-temperature anode exhaust gas discharged from the fuel cell stack 11 is introduced into the exhaust gas burner 13 for combustion.

[0042] b. Pass the high-temperature flue gas generated by combustion into the waste heat recovery pipeline and use its heat to perform the following operations: Operation 1 (Molten Salt Reheating): Heat the reflux molten salt flowing out of the low-temperature molten salt tank 2.

[0043] Operation 2 (Catalytic Reforming): Provides heat for the methanol-water vapor reaction in reforming reactor 10.

[0044] Operation 3 (Steam Generation): Evaporate the methanol-water solution flowing to Steam Generator 9.

[0045] During the power generation stage, the reforming reaction temperature is controlled between 200°C and 600°C by dynamically adjusting the flow rate of molten salt through the catalytic reformer 10; and the heat recovered by the waste heat recovery system is dynamically allocated to prioritize the heating of the reflux molten salt.

[0046] Example 1: This embodiment details the preparation method of the composite phase change thermal storage molten salt used in the energy storage system of the present invention.

[0047] 1. Raw materials and proportions: a. Matrix molten salt: Industrial grade sodium nitrate (NaNO3) and potassium nitrate (KNO3) are prepared in a mass ratio of 60:40.

[0048] b. Nano-additives: hydrophilic fumed silica nanoparticles (particle size 7-40 nm), added at 2.0% of the total mass of the matrix molten salt; multi-walled carbon nanotubes (outer diameter <8 nm, length 10-30 μm), added at 1.0% of the total mass of the matrix molten salt.

[0049] c. Dispersion medium: anhydrous ethanol.

[0050] 2. Preparation equipment: electronic balance, planetary ball mill, high-temperature melting furnace, mechanical stirrer (with heating function, speed adjustable from 0-1500 rpm), ultrasonic cell disruptor.

[0051] 3. Preparation steps: a. Base Salt Mixing and Initial Melting: Weigh out sodium nitrate and potassium nitrate powders and mix them in a planetary ball mill for 2 hours to ensure initial uniformity. Transfer the mixed salt to a high-temperature melting furnace and heat it to 300°C at a rate of 5°C / min, and hold it until completely melted to form a uniform Solar Salt base salt liquid.

[0052] b. Nanoparticle slurry pretreatment: Weighed silica nanoparticles and carbon nanotubes are added to an appropriate amount of anhydrous ethanol and ultrasonically dispersed for 30 minutes at 800W using an ultrasonic cell disruptor to form a stable nanomaterial suspension.

[0053] c. High-temperature composite: The molten base salt liquid is transferred to a reactor equipped with heating and mechanical stirring, and the temperature is maintained at 350°C. Under high-speed mechanical stirring (speed set to 1000 rpm), the above-mentioned nano-suspension is slowly and uniformly added to the molten salt using a constant-pressure dropping funnel. This process lasts for about 1 hour.

[0054] d. Solvent evaporation and aging: After the addition is complete, maintain stirring and heat to 400°C. Continue stirring at this temperature for 2 hours to ensure that the anhydrous ethanol evaporates completely and that the nanomaterials are fully dispersed and aged in the molten salt.

[0055] e. Cooling and Shaping: Remove the reactor from the heat source and allow it to cool naturally to room temperature with continuous stirring to obtain a gray-black, solid composite phase change thermal storage molten salt block. When needed, reheat to above its melting point.

[0056] Example 2: See Figure 1 The schematic diagram of the system structure of the present invention shown illustrates a molten salt heating type methanol reforming fuel cell energy storage device, which includes a molten salt energy storage system, a methanol reforming hydrogen production system, a solid oxide fuel cell power generation system, and a thermal management and control system.

[0057] 1. Molten Salt Energy Storage System: The composite phase change thermal storage molten salt prepared in Example 1 is used as the thermal storage medium, with an operating temperature range of 290℃ to 565℃. The system includes a high-temperature molten salt tank 1 and a low-temperature molten salt tank 2, which are connected by a molten salt pipeline. The pipeline is equipped with a molten salt pump 3 and a molten salt heat exchanger 4. The system is equipped with an electric heater (not shown), whose heating element is inserted into the outlet pipeline of the low-temperature molten salt tank 2, for heating the molten salt using electrical energy during the energy storage phase. As another heat source input, the system can also optionally connect an external waste heat exchanger (6 not shown) for recovering the waste heat of the 400-500℃ exhaust gas from industrial kilns.

[0058] 2. Methanol Reforming Hydrogen Production System: An aqueous methanol solution is stored in storage tank 7 and transported by pump 8. After being heated to approximately 180°C by steam generator 9, it is atomized and injected into reforming reactor 10 to produce hydrogen. Reforming reactor 10 employs a jacketed structure, with a sealed heat-conducting oil flow channel jacket surrounding the reaction tube walls. This flow channel jacket is connected to molten salt exothermic heat exchanger 4 via pipelines.

[0059] 3. Fuel Cell Power Generation System: A planar solid oxide fuel cell (SOFC) stack with biomimetic flow channels is adopted, with a rated operating temperature of 750°C. The anode inlet of the fuel cell stack 11 is connected to the outlet of the reforming reactor 10 via a reforming gas delivery pipeline, with a gas purification device (not shown) in between to remove trace impurities that may be toxic to the electrodes. The cathode inlet of the fuel cell stack 11 is connected to an air blower (air supply device 12) to provide oxidant and control the stack temperature.

[0060] 4. Thermal Management System: The anode exhaust outlet of the fuel cell stack 11 is connected to the catalytic burner 13 through a pipeline. It mixes with the added air and, under the action of the catalyst, completely burns the unreacted combustible components such as H2 and CO, producing high-temperature flue gas of about 800°C.

[0061] In this embodiment, the high-temperature flue gas is configured to flow through a multi-stage heat exchange pipeline: First stage (high temperature heat recovery): High-temperature flue gas at 800℃ flows through molten salt heat exchanger 4, directly transferring its heat to the molten salt flowing out from low-temperature molten salt tank 2 (heated from 250℃ to 400℃), realizing the return of heat to the core of the molten salt system.

[0062] Second stage (medium-temperature heat recovery): Flue gas at ~400°C from molten salt heat exchanger 4 flows sequentially through catalytic reformer 10 and steam generator 9, providing heat for the methanol-water reforming reaction and gasification.

[0063] Finally, the flue gas, with its temperature reduced to ~150°C, was discharged from the system.

[0064] The working process and method of the device: 1. Energy Storage Stage: When the system receives off-peak electricity or wind and solar power curtailment from the grid, it starts the electric heater. Molten salt pump 3 operates at low speed, pumping molten salt at approximately 300°C from the low-temperature molten salt tank 2. The molten salt flows through the electric heater, is heated to 565°C, and then stored in the high-temperature molten salt tank 1, completing the conversion and storage of electrical energy into thermal energy.

[0065] 2. Hydrogen Production Stage: Increase the speed of molten salt pump 3 to pump high-temperature molten salt (565℃) from high-temperature molten salt tank 1. After flowing through molten salt exothermic heat exchanger 4, it is heated and enters the jacket of reforming reactor 10. By adjusting the molten salt flow rate, the bed temperature of reforming reactor 10 is stably controlled at 280℃~300℃. Simultaneously start transfer pump 8 and air blower 12. A methanol-water solution prepared at a molar ratio of 1:1.3 is pumped by transfer pump 8 into steam generator 9, where it is converted into a methanol-water vapor mixture (~200℃) using medium-grade waste heat before entering reforming reactor 10. Under the action of a catalyst, a reforming reaction occurs, producing a mixed reformed gas with H2, CO2, and CO components.

[0066] 3. Power Generation Stage: The generated reformed gas, after cooling and dehydration, is transported to the anode of the SOFC stack 11. At 750°C, H2 and CO undergo electrochemical oxidation at the anode to generate direct current, which is then connected to the power grid or supplied to the load via an inverter (not shown). In this stage, thanks to the biomimetic fractal flow channel, the reactant gas achieves uniform distribution on the electrode surface, thereby obtaining higher power generation efficiency.

[0067] 4. Exhaust Gas Treatment and Waste Heat Recovery Stage: The ~700°C anode exhaust gas from the SOFC mixes with the cathode exhaust gas and enters a high-temperature exhaust gas burner 13, where unreacted fuel is completely burned, producing high-temperature flue gas at ~800°C. This flue gas flows through the molten salt heat exchanger 4, directly transferring its heat to the molten salt flowing out of the low-temperature molten salt tank 2, achieving heat return to the core of the molten salt system. The ~400°C flue gas from the molten salt heat exchanger 4 flows sequentially through the catalytic reformer 10 and the steam generator 9, providing heat for the methanol-water reforming reaction and gasification. Finally, the flue gas, with its temperature reduced to ~150°C, is discharged from the system.

[0068] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A molten salt heating type methanol reforming fuel cell energy storage device, characterized in that: include Molten salt energy storage systems are used to receive and store electrical energy or thermal energy converted from industrial waste heat. The methanol reforming hydrogen production system uses a molten salt energy storage system as a heat source for the methanol reforming reaction. The fuel cell power generation system is connected to the methanol reforming hydrogen production system, receiving hydrogen-rich reformed gas for power generation. A waste heat recovery system is used to transfer the recovered heat to the molten salt energy storage system and / or the methanol reforming hydrogen production system.

2. The molten salt heating type methanol reforming fuel cell energy storage device according to claim 1, characterized in that: The molten salt energy storage system includes a molten salt heat exchanger (4), a low-temperature molten salt tank (2), a molten salt pump (3), a high-temperature molten salt tank (1) connected in sequence through a molten salt heat release circuit, and an external heat source input device to provide heat to the molten salt in the low-temperature molten salt tank (2).

3. The molten salt heating type methanol reforming fuel cell energy storage device according to claim 2, characterized in that: The molten salt used in the molten salt energy storage system is a composite phase change thermal storage molten salt, which is composed of a matrix molten salt and uniformly dispersed nanomaterials therein. The matrix molten salt is a mixture of sodium nitrate and potassium nitrate. The nanomaterials include hydrophilic fumed silica nanoparticles and carbon nanotubes.

4. The molten salt heating type methanol reforming fuel cell energy storage device according to claim 1, characterized in that: The methanol reforming hydrogen production system includes a methanol aqueous solution storage tank (7), a transfer pump (8), a steam generator (9), and a catalytic reformer (10) connected in sequence; the shell-side flow channel inlet and outlet of the catalytic reformer (10) are connected to the low-temperature side pipeline of the molten salt exothermic heat exchanger (4).

5. The molten salt heating type methanol reforming fuel cell energy storage device according to claim 4, characterized in that: The catalytic reformer (10) integrates a serrated tube bundle arranged in a spiral twist, which is inclined and wound from top to bottom with a fixed pitch to form a spiral tube bundle bed structure. The catalytic reformer (10) is provided with several arc-shaped support plates, which are evenly distributed at different heights to support and constrain the spiral tube bundle, ensuring that the fluid flows along the spiral path in the shell side of the catalytic reformer (10).

6. The molten salt heating type methanol reforming fuel cell energy storage device according to claim 1, characterized in that: The fuel cell power generation system includes a fuel cell stack (11), the anode inlet of the fuel cell stack (11) is connected to the gas production outlet of the catalytic reformer (10), and the cathode inlet of the fuel cell stack (11) is connected to an air supply device (12).

7. The molten salt heating type methanol reforming fuel cell energy storage device according to claim 6, characterized in that: The anode and cathode bipolar plates of the fuel cell stack (11) are designed with a biomimetic fractal flow channel that mimics the veins of plant leaves. The flow channel structure consists of a primary main flow channel and a secondary branch flow channel, with a smooth transition between each flow channel.

8. The molten salt heating type methanol reforming fuel cell energy storage device according to claim 7, characterized in that: The waste heat recovery system includes: a tail gas burner (13) connected to the anode tail gas outlet of the fuel cell stack (11), and a waste heat recovery pipeline installed at the flue gas outlet end of the tail gas burner (13). The waste heat recovery pipeline includes the following units: Molten salt reheating: High-temperature flue gas flows through the reheating heat exchanger, and its cold side is connected in series to the molten salt return pipeline from the low-temperature molten salt tank (2) to the external heat source input equipment or the high-temperature molten salt tank (1); Catalytic reforming: The medium-temperature flue gas flows through a heat exchanger, the cold side of which is connected in series in the pipeline of the reforming reactor (10); Steam generation: Low-temperature flue gas flows through a heat exchanger, the cold side of which is connected in series with the pipeline of the steam generator (9).

9. A method for energy storage and power supply using a molten salt heating type methanol reforming fuel cell energy storage device as described in any one of claims 1-8, characterized in that: Includes the following steps: S1. Energy storage stage: Utilize off-peak electricity from the power grid, abandoned renewable energy, or industrial waste heat to heat the molten salt flowing out of the low-temperature molten salt tank (2) through the external heat source input device, and store the heated high-temperature molten salt in the high-temperature molten salt tank (1); S2. Power generation stage: S21. Drive the high-temperature molten salt through the molten salt exothermic heat exchanger (4) to provide reaction heat for the catalytic reformer (10); S22. Methanol and water are fed into the steam generator (9) and the catalytic reformer (10) to undergo a reforming reaction under molten salt heating to generate reformed gas; S23. The high-purity hydrogen gas is delivered to the anode of the fuel cell stack (11) to carry out an electrochemical reaction and generate electrical energy; S24. The anode tail gas discharged from the fuel cell stack (11) is fed into the tail gas burner (13) for combustion, and the generated high-temperature flue gas is fed into the waste heat recovery pipeline to recover its heat for heating the reflux molten salt and / or for catalytic reforming and steam generation.

10. The energy storage and power supply method of the molten salt heating type methanol reforming fuel cell energy storage device according to claim 9, characterized in that: During the power generation stage, the reforming reaction temperature is controlled between 200°C and 600°C by dynamically adjusting the flow rate of molten salt through the catalytic reformer (10); and the heat recovered by the waste heat recovery system is dynamically distributed.

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