Biomass supercritical water gasification hydrogen production system and method based on heat energy self-circulation and heat stirring enhancement

Abstract

The invention discloses a biomass supercritical water gasification hydrogen production system and method based on heat energy self-circulation and heat stirring intensification, and belongs to the technical field of hydrogen production energy. The system comprises a supercritical water gasification reaction device, the top of the supercritical water gasification reaction device is connected with a storage tank, the bottom of the supercritical water gasification reaction device is connected with a water tank and a slag collecting device, and a stirring device and a palladium membrane are arranged in the supercritical water gasification reaction device; a solar heater is arranged outside; a heat conversion device is arranged on the supercritical water gasification reaction device; a gas outlet of the supercritical water gasification reaction device is connected with a decompression separator, and a gas outlet of the decompression separator is connected with a carbon monoxide combustion device. The supercritical water gasification system is used for solving the technical problems that a traditional supercritical water gasification system is low in internal heat transfer efficiency and insufficient in material mixing.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen production energy technology, specifically relating to a system and method for producing hydrogen from biomass supercritical water gasification based on thermal energy self-circulation and enhanced thermal stirring. Background Technology

[0002] Biomass, as a widely distributed, renewable, and carbon-neutral resource, is a key area of ​​current clean energy research. Utilizing biomass to produce hydrogen not only helps alleviate the fossil fuel crisis but also effectively reduces greenhouse gas emissions. Supercritical water gasification technology, leveraging the unique physical and chemical properties of water above its critical point, can efficiently convert high-moisture-content biomass directly into gases such as hydrogen, carbon monoxide, and carbon dioxide without the need for drying pretreatment. This avoids the high energy consumption and pollution problems of traditional thermochemical pathways, demonstrating significant advantages in resource utilization and environmental protection.

[0003] However, existing supercritical water gasification systems still face many bottlenecks in practical engineering applications, such as harsh reaction conditions, low internal heat transfer efficiency, insufficient material mixing, and low energy utilization efficiency. In particular, since traditional devices mainly rely on external wall heating, there is a significant delay and attenuation in the transfer of heat from the inside of the reactor to the center, making it difficult to reach the ideal temperature in the core reaction zone, thus affecting gasification efficiency and hydrogen production rate.

[0004] Furthermore, traditional supercritical water gasification systems generally rely on external heat sources for energy supply, resulting in limited energy self-sufficiency and restricting their application in remote areas or regions with difficult energy access. Therefore, developing gasification devices with energy recovery and self-circulation capabilities has become a research hotspot. Recovering the heat generated during the reaction to provide energy input to the system not only helps improve energy utilization efficiency but also enables partial self-heating operation, enhancing the system's economy and sustainability. Traditional devices also suffer from large temperature gradients and incomplete reactions, leading to low gasification efficiency and poor hydrogen production performance.

[0005] In summary, there is an urgent need to propose a biomass supercritical water gasification hydrogen production system that integrates a thermal stirring device and has heat recovery and self-circulation functions, in order to break through the existing technical bottlenecks and improve the overall reaction performance and engineering adaptability. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention aims to provide a system and method for producing hydrogen from biomass supercritical water gasification based on thermal energy self-circulation and thermal stirring enhancement, so as to solve the technical problems of low internal heat transfer efficiency and insufficient material mixing in traditional supercritical water gasification systems.

[0007] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a biomass supercritical water gasification hydrogen production system based on thermal energy self-circulation and thermal stirring enhancement. The system is characterized by including a supercritical water gasification reactor, wherein the top of the supercritical water gasification reactor is connected to a storage tank, the bottom is connected to a water tank and a slag collection device, the internal part is equipped with a stirring device and a palladium membrane, and the external part is equipped with a solar heater. The supercritical water gasification reactor is equipped with a heat conversion device, and a hydrogen storage tank and a gas collection bottle are connected to the outlet of the heat conversion device. The outlet of the supercritical water gasification reactor is connected to a pressure reducing separator, the outlet of the pressure reducing separator is connected to a carbon monoxide combustion device, and the inlet of the carbon monoxide combustion device is connected to an oxygen cylinder.

[0008] The system comprises the following components: a storage tank for storing biomass feedstock; a water tank for storing water; a solar heater for preheating during system startup; a water pump connected to the water tank outlet for water delivery; a palladium membrane for hydrogen separation; a slag hopper for collecting solid residue; a feed pump for transporting biomass feedstock; a first heat exchanger for heat recovery; a second heat exchanger for further heat conversion; a carbon monoxide combustion device for burning carbon monoxide to generate heat; an inlet pipe for uniformly injecting oxygen; a hydrogen storage tank for storing hydrogen; a gas collecting bottle for collecting carbon dioxide; an oxygen cylinder for providing oxygen; and a pressure reducing separator for gas-liquid separation and pressure reduction. The system achieves self-circulation of thermal energy through the heat exchangers and enhances reaction efficiency through a stirring paddle. The stirring paddle is made of high-temperature and corrosion-resistant materials, with uniformly distributed blades that directly heat the core reaction area during stirring, reducing the temperature gradient and improving gasification efficiency.

[0009] Preferably, the heat conversion device includes a first heat converter and a second heat converter, the first heat converter being connected to the hydrogen outlet of the supercritical water gasification reactor, and the second heat converter being connected to the outlet of the carbon monoxide combustion device.

[0010] Preferably, the stirring device is a stirring paddle with stirring and heating functions, used to enhance the uniformity of material mixing and reaction, and the stirring paddle is provided with several blades.

[0011] Preferably, the palladium membrane is a selective permeation membrane, which can separate hydrogen in real time during the reaction process, ensuring that the purity of hydrogen is not less than 99%, and continuously output to the first heat exchanger.

[0012] Preferably, the air inlet of the carbon monoxide combustion device is connected to the oxygen cylinder via an air inlet tube, and the surface of the air inlet tube is provided with evenly distributed holes.

[0013] Preferably, the heat conversion device adopts a counter-current heat exchange to recover the heat energy generated by the combustion of hydrogen and carbon monoxide, and to provide auxiliary heating for the supercritical water gasification reactor, feed pump and water pump, so as to realize the cascade utilization of heat energy.

[0014] The present invention also provides a method for the above-mentioned biomass supercritical water gasification hydrogen production system based on thermal energy self-circulation and thermal stirring enhancement, comprising the following steps: The supercritical water gasification reactor is preheated using a solar heater. Start the stirring device to stir and assist heating inside the supercritical water gasification reactor; Biomass feedstock in storage tanks is fed into the top of the supercritical water gasification reactor, while water in water tanks is fed into the bottom of the supercritical water gasification reactor to form a counter-flow to enhance contact. In a supercritical water gasification reactor, biomass is gasified under high temperature and high pressure to produce hydrogen, carbon monoxide and carbon dioxide. Hydrogen gas is separated using a palladium membrane and then transported to a first heat exchanger for heat recovery. The remaining gas is separated by a pressure reducing separator, the gaseous products are burned in a carbon monoxide combustion device, and the liquid water is recycled to a supercritical water gasification reactor. Carbon monoxide is converted into carbon dioxide through a carbon monoxide combustion device, and the released heat energy is used to heat the second heat exchanger. The recovered heat energy is used to maintain the reaction temperature and water circulation, enabling the system to operate in a self-circulating manner.

[0015] Preferably, in the preheating step, the solar heater raises the initial temperature of the system to 300-400°C, and then relies on heat recovery to maintain the reaction temperature at a supercritical state above 374°C.

[0016] Preferably, in the hydrogen separation step, the palladium membrane operates at a pressure of 20-25 MPa and a temperature of 300-500°C.

[0017] Preferably, the heat recovery step includes: using the waste heat of hydrogen to heat the feed pipeline through a first heat converter, and using the combustion heat of carbon monoxide to heat the water supply pipeline through a second heat converter, forming a closed-loop energy utilization and reducing dependence on external energy.

[0018] Furthermore, the supercritical water gasification reactor of this invention is equipped with a palladium membrane for hydrogen separation, which can efficiently separate hydrogen from the complex reaction mixture during the reaction process, improving the purity of the hydrogen and ensuring continuous and stable hydrogen production, providing a high-quality gas source for subsequent hydrogen collection and utilization. The separated hydrogen also ensures that there is no risk of explosion in the subsequent carbon monoxide combustion device.

[0019] Furthermore, this invention incorporates a depressurization separation device within the system to reduce the pressure of the supercritical mixed gas (mainly carbon monoxide and carbon dioxide) to a subcritical state, achieving effective separation of the gas and liquid phases. The separated gas enters a second heat exchanger for subsequent energy recovery, while the separated water is recycled and reintroduced into the supercritical water gasification reactor, forming a closed-loop cycle. This design not only improves the system's energy efficiency and reduces dependence on external water resources but also lowers operating costs and enhances overall sustainability and environmental performance.

[0020] Furthermore, this invention incorporates a carbon monoxide combustion device, introducing carbon monoxide and carbon dioxide gases from the gaseous products of the supercritical water gasification device after passing through a pressure-reducing separator, and introducing a high concentration of oxygen. This allows the carbon monoxide to burn rapidly and completely under high-temperature conditions, releasing a large amount of heat energy. This process not only effectively improves the system's heat recovery rate, providing a reusable heat source for reactions or other related processes, but also enhances overall energy utilization efficiency and reduces external heating requirements, thereby contributing to energy conservation and emission reduction goals. In addition, this combustion process can achieve the harmless treatment of carbon monoxide, reducing its environmental risks.

[0021] Furthermore, this invention incorporates a heat exchanger, directly introducing the carbon dioxide produced by combustion and the existing carbon dioxide into the heat exchanger. This not only utilizes the high-temperature gas to provide heat energy for the device but also enables efficient collection of carbon dioxide. This structural design effectively avoids the difficulties and high costs associated with separating the mixed carbon monoxide and carbon dioxide in traditional systems, simplifying and optimizing the gas production process. Simultaneously, the collected high-purity carbon dioxide can be directly applied to other industrial uses, such as food preservation, gas fire suppression, and greenhouse gas utilization, improving the comprehensive utilization rate of resources and enhancing the device's green environmental characteristics and industrial application value.

[0022] Furthermore, this invention incorporates an oxygen inlet pipe within the carbon monoxide combustion device. This inlet pipe has evenly distributed holes to ensure uniform oxygen release within the reaction zone. This design effectively enhances the contact area between the gas and the reaction medium, promoting a more complete reaction and improving gasification efficiency.

[0023] Furthermore, this invention utilizes solar energy as the primary energy source in the early stages of the system reaction. A solar heating device provides the necessary heat for the reaction process, and the heat from the reaction products is continuously supplied to the supercritical gasification reactor, material pipelines, and water pipelines via a heat exchanger. This design achieves internal energy circulation within the system, eliminating the need for external energy supply, reducing operating costs, and enhancing the system's green environmental performance and energy self-sufficiency.

[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention addresses the low heat transfer efficiency in supercritical water gasification by innovatively designing a reactor feed and water inlet structure: the material is sprayed in from the top of the reactor, while water is introduced from the bottom by a pump. This bidirectional feeding method, from top to bottom and bottom to top, creates counter-current flows between the material and water inside the reactor, significantly enhancing the contact interface and mixing degree. This effectively promotes heat and mass exchange and reaction rate under supercritical conditions, thereby optimizing reaction conditions and improving gasification efficiency and product quality. Simultaneously, this structural design also helps to rationally distribute the heat of reaction, avoiding localized overheating or cold spots, and ensuring the stability and continuity of the reaction process.

[0025] To improve the temperature uniformity and reaction completeness of the reaction system, this invention incorporates a stirring device with high temperature and corrosion resistance inside the reactor. This device combines stirring and heating functions, which not only enhances the transfer of matter and energy in the reaction zone and increases the contact frequency between reactants and catalysts, but also provides directional heating to the core reaction zone directly through an internal heating mechanism.

[0026] By recovering waste heat from the reaction through a heat conversion device to provide auxiliary heating for the system, dependence on external energy sources is significantly reduced, and energy utilization efficiency is improved. The carbon monoxide combustion device and heat recovery achieve the harmless treatment of greenhouse gases, meeting the requirements for green hydrogen production.

[0027] Furthermore, the stirring device consists of several rationally distributed stirring blades, which continuously break up the agglomeration of raw materials during operation, significantly enhancing the fluidity and mixing efficiency of the reaction medium throughout the reaction space. The integrated multi-bladed internally heated stirring paddle combines stirring and heating functions, solving the temperature gradient problem caused by traditional external heating. This results in a more uniform temperature distribution inside the reactor, increasing gasification efficiency by approximately 20%. Simultaneously, the stirring device itself integrates heating functionality, providing auxiliary heating to the reaction chamber. This effectively compensates for the excessive internal temperature gradient caused by external heating in traditional devices, achieving internal and external temperature equilibrium and improving reaction rate and conversion efficiency. This device not only helps reduce the formation of unreacted substances and residual carbon but also inhibits bottom sedimentation and slagging, thereby extending equipment lifespan, reducing operating and maintenance costs, and enhancing system stability and economy.

[0028] Furthermore, heat conversion device Furthermore, the high selectivity of the palladium membrane eliminates the need for subsequent purification steps, directly producing high-purity hydrogen that meets fuel cell or industrial hydrogen standards, simplifying the process. In-situ separation enables continuous hydrogen collection, avoiding the intermittent issues of batch processing and increasing system capacity. Timely hydrogen separation reduces the risk of explosion within the reactor, and enhances operational safety, especially in the presence of carbon monoxide.

[0029] Furthermore, the perforated design ensures thorough mixing of oxygen and carbon monoxide, resulting in a more complete combustion reaction, improved carbon monoxide conversion rate, and reduced harmful gas emissions. Complete combustion releases a large amount of heat energy, which is effectively recovered through the heat exchanger, providing a stable heat source for the system and reducing external heating requirements. Uniform air intake avoids localized high temperatures or flameout, extending the lifespan of the device.

[0030] Furthermore, counter-current heat exchange improves heat transfer efficiency, significantly increasing waste heat recovery and substantially reducing total system energy consumption. The recovered heat energy is directly used to preheat feed and water sources, achieving an energy closed loop, making it particularly suitable for remote areas or off-grid applications. Simultaneously, it reduces dependence on electricity or fossil fuels and lowers operating costs.

[0031] This invention also provides a method for the above-mentioned biomass supercritical water gasification hydrogen production system based on thermal energy self-circulation and enhanced thermal stirring. Through solar preheating and enhanced thermal stirring, the reaction start-up time is shortened and the production capacity is increased. The top-down feeding method of biomass and bottom-up feeding of water enhances mixing efficiency, resulting in a more complete gasification reaction and increased hydrogen yield. Water separated by depressurization is reused in the reaction unit, reducing water consumption and achieving zero wastewater discharge. The method covers the entire chain from raw materials to products, ensuring operational continuity and repeatability.

[0032] Furthermore, using solar energy as the initial heat source avoids the use of fossil fuels, reducing the carbon footprint and meeting the requirements of sustainable development. The preset temperature range ensures rapid formation of supercritical water, avoiding energy waste and improving reaction start-up efficiency. The free nature of solar energy reduces system operating costs, making it particularly suitable for areas with abundant sunshine.

[0033] Furthermore, a specific pressure and temperature range ensures optimal permeability of the palladium membrane, significantly improving hydrogen recovery. Parameters are matched to supercritical water vaporization conditions, avoiding additional energy input and simplifying integrated design. Controllable operating conditions reduce the risk of membrane damage and extend equipment lifespan.

[0034] Furthermore, the closed-loop design increases the system's energy self-sufficiency rate, reducing dependence on the external power grid. Low operating costs improve the return on investment, making it particularly suitable for large-scale hydrogen production projects. The near-zero emissions from end-to-end heat recovery support carbon neutrality goals. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the biomass supercritical water gasification hydrogen production system of the present invention.

[0036] The components are: 1-storage tank; 2-water tank; 3-solar heater; 4-water pump; 5-supercritical water gasification reactor; 6-multi-blade internally heated stirring paddle; 7-palladium membrane; 8-slag hopper; 9-pump; 10-first heat exchanger; 11-second heat exchanger; 12-carbon monoxide combustion device; 13-gas inlet pipe; 14-hydrogen storage tank; 15-gas collecting bottle; 16-oxygen cylinder; 17-pressure reducing separator. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings: It should be understood that the structural diagrams disclosed in this invention are not drawn to scale. Some diagrams are only used to help readers better understand the structure and working principle of this invention, rather than to accurately show the actual structure of the device.

[0040] See Figure 1The supercritical water gasification reactor 5 has a material inlet at the top connected to the material outlet of the storage tank 1 via a pipeline; an energy inlet at the top connected to the energy outlet of the first heat converter 10; a solar heater 3 connected to one side of the supercritical water gasification reactor 5; a water inlet at the bottom connected to the outlet of the water tank 2; a residue outlet at the bottom connected to the residue inlet of the slag hopper 8; a gas outlet at the bottom connected to the gas inlet of the pressure reducing separator 17; a gas outlet at the pressure reducing separator 17 connected to the gas inlet of the carbon monoxide combustion device 12; a water outlet on one side connected to the water inlet at the bottom of the supercritical water gasification reactor 5; and two palladium membranes 7 and a stirring paddle 6 with stirring and heating functions, arranged from left to right inside the supercritical water gasification reactor 5, with four blades on the stirring paddle 6.

[0041] The first heat exchanger 10 is located at the hydrogen outlet of the supercritical water gasification reactor 5. The two energy outlets at the upper end of the first heat exchanger 10 are connected to the energy inlet of the feed pump 9 and the energy inlet of the supercritical water gasification reactor 5, respectively. The right outlet of the first heat exchanger 10 is connected to the inlet of the hydrogen storage tank 14. The inlet of the carbon monoxide combustion device 12 is connected to the outlet of the pressure reducing separator 17. The top inlet of the carbon monoxide combustion device 12 is connected to the outlet of the oxygen cylinder 16. An inlet pipe 13 is provided inside the carbon monoxide combustion device 12. The bottom outlet of the carbon monoxide combustion device 12 is connected to the inlet of the second heat exchanger 11. The energy outlet at the bottom left of the second heat converter 11 is connected to the energy inlet of the water pump 4; the air outlet at the bottom of the second heat converter 11 is connected to the air inlet of the gas collecting bottle 15.

[0042] The working principle and workflow of the above-mentioned biomass supercritical water gasification hydrogen production system and method based on thermal energy self-circulation and thermal stirring enhancement are as follows: The biomass feedstock in storage tank 1 is pumped by feed pump 9 to the upper left material inlet of supercritical water gasification reactor 5; water in water tank 2 enters the lower left water inlet of reactor 5 driven by water pump 4. At the initial stage of system startup, solar heater 3 is first turned on to preheat supercritical water gasification reactor 5, providing initial reaction temperature conditions; subsequently, the agitator 6, which integrates heating and stirring functions, is activated to ensure thorough mixing and maintain temperature equilibrium within the reaction system, significantly improving reaction uniformity and conversion efficiency.

[0043] The hydrogen generated during the reaction undergoes selective permeation separation via a palladium membrane separator 7 before entering the first heat exchanger 10. This heat exchanger absorbs the heat energy carried by the high-temperature hydrogen gas to provide secondary heating for the supercritical water gasification reactor 5 and its raw material conveying pipelines, thus achieving partial heat energy recovery and utilization. The hydrogen gas, after releasing heat, is then piped into a hydrogen storage tank 14 for storage.

[0044] Meanwhile, the carbon dioxide and carbon monoxide generated in the reaction are discharged from the outlet at the bottom of the reaction device 5 and enter the inlet of the pressure reducing separator 17. This device converts the supercritical mixed gas into a subcritical state by reducing the pressure, thus achieving gas-liquid separation. The separated CO and CO2 gases are sequentially introduced into the carbon monoxide combustion device 12, where oxygen from the oxygen cylinder 16 is uniformly injected through the inlet pipe 13 with multiple outlet holes, and undergoes high-temperature combustion with the carbon monoxide, promoting its conversion into carbon dioxide.

[0045] The high-temperature CO2 gas produced by combustion, along with the original CO2, is introduced into the second heat exchanger 11 through the inlet. Its heat energy is used to heat the supercritical water gasification reactor 5 and the water pipeline, realizing the cascade recovery and reuse of heat energy. After heat exchange, the carbon dioxide gas is transported through pipelines to the gas collecting bottle 15 for centralized collection.

[0046] In addition, a water outlet is provided on the right side of the pressure reducing separator 17 to discharge the separated water. This water is reintroduced into the reaction chamber through the water inlet at the bottom of the reaction device 5, forming a closed water circulation system. After the reaction is completed, the residue discharge outlet at the bottom of the reaction device 5 is opened, and the generated solid residue is guided into the slag hopper 8 for centralized collection and treatment, ensuring the cleanliness and maintainability of the system operation.

[0047] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A system for hydrogen production by supercritical water gasification of biomass based on thermal energy self-circulation and thermal agitation intensification, characterized in that, The supercritical water gasification reaction device (5) is provided with a storage tank (1) at the top, a water tank (2) and a slag collecting device at the bottom, a stirring device and a palladium membrane (7) inside, and a solar heater (3) outside. A heat conversion device is arranged on the supercritical water gasification reaction device (5), and a hydrogen storage tank (14) and a gas collecting bottle (15) are connected to the outlet of the heat conversion device. A pressure reducing separator (17) is connected to the gas outlet of the supercritical water gasification reaction device (5), and a carbon monoxide combustion device (12) is connected to the gas outlet of the pressure reducing separator (17).

2. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-circulation and thermal agitation intensification according to claim 1, characterized in that, The stirring device is a stirring paddle (6) with stirring and heating functions, and a plurality of blades are arranged on the stirring paddle (6).

3. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-circulation and thermal agitation intensification according to claim 1, characterized in that, The heat conversion device comprises a first heat converter (10) and a second heat converter (11), wherein the first heat converter (10) is connected to the hydrogen outlet of the supercritical water gasification reaction device (5), and the second heat converter (11) is connected to the outlet of the carbon monoxide combustion device (12).

4. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-circulation and thermal agitation intensification according to claim 1, characterized in that, The palladium membrane (7) is a selective permeation membrane.

5. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-circulation and thermal agitation intensification according to claim 1, characterized in that, The gas inlet of the carbon monoxide combustion device (12) is connected to the oxygen cylinder (16) through a gas inlet cannula (13), and the surface of the gas inlet cannula (13) is provided with uniformly distributed holes.

6. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-cycling and thermal agitation intensification according to claim 1, characterized in that, The heat conversion device adopts a counter-flow heat exchange mode.

7. The method of the biomass supercritical water gasification system for hydrogen production based on thermal energy self-circulation and thermal agitation intensification according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: The supercritical water gasification reaction device (5) is preheated by the solar heater (3); The stirring device is started to stir and assist heating in the supercritical water gasification reaction device (5); The biomass raw material in the storage tank (1) is input from the top of the supercritical water gasification reaction device (5), and the water in the water tank (2) is input from the bottom of the supercritical water gasification reaction device (5) to form a reverse flow to enhance the contact; In the supercritical water gasification reaction device (5), the biomass is gasified at high temperature and high pressure to produce hydrogen, carbon monoxide and carbon dioxide; The hydrogen is separated by the palladium membrane (7) and transported to the first heat converter (10) for heat recovery; The remaining gas is separated by the pressure reducing separator (17), the gas phase product is burned in the carbon monoxide combustion device (12), and the liquid phase water is reused in the supercritical water gasification reaction device (5); The carbon monoxide is converted into carbon dioxide by the carbon monoxide combustion device (12), and heat energy is released to heat the second heat converter (11); The recovered heat energy is used to maintain the reaction temperature and water circulation, and the system is operated in a self-circulation mode.

8. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-circulation and thermal agitation intensification according to claim 7, characterized in that, In the preheating step, the solar heater (3) raises the initial temperature of the system to 300-400℃, and then relies on heat recovery to maintain the reaction temperature above 374℃ in a supercritical state.

9. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-circulation and thermal agitation intensification according to claim 7, characterized in that, In the hydrogen separation step, the operating pressure of the palladium membrane (7) is 20-25MPa, and the temperature is maintained at 300-500℃.

10. The system for hydrogen production from biomass gasification in supercritical water based on thermal self-circulation and thermal agitation intensification according to claim 7, characterized in that, The heat energy recovery step comprises: heating the feed pipeline by hydrogen waste heat through a first heat converter (10), and heating the water supply pipeline by carbon monoxide combustion heat through a second heat converter (11), forming a closed-loop energy utilization and reducing external energy dependence.

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