A solar-driven biomass continuous pyrolysis system and method based on thermo-chemical heat storage

Abstract

The application discloses a kind of solar-driven biomass continuous pyrolysis system and method based on thermochemical heat storage, system includes: solar heat collecting unit, for collecting solar radiation energy;Biomass pyrolysis reaction unit is equipped with biomass feed inlet and product discharge port;Thermochemical heat storage unit is equipped with CO2 import and CO2 export, internally filled with thermochemical heat storage material with MgO / MgCO3 as active component;Thermochemical heat storage unit is respectively with solar heat collecting unit and biomass pyrolysis reaction unit by heat exchange medium circulation pipeline heat exchange;CO2 circulation subsystem;Control system, with solar heat collecting unit, biomass pyrolysis reaction unit, thermochemical heat storage unit and CO2 circulation subsystem electric connection, according to preset parameter automatic adjustment operating mode and heat exchange medium flow.This scheme will unstable solar energy into chemical energy storage, and release in the form of heat energy, for biomass pyrolysis provides continuous, controllable heat source.

Description

Technical Field

[0001] This invention belongs to the field of renewable energy utilization and solid waste treatment technology, and specifically relates to a solar-driven continuous biomass pyrolysis system and method based on thermochemical thermal storage. Background Technology

[0002] Biomass pyrolysis refers to the process of heating biomass under an inert atmosphere to decompose it into bio-oil, pyrolysis gas, and biochar. This technology has advantages such as resource recovery, volume reduction, and low carbon emissions, and is one of the important ways to realize the energy utilization of biomass. However, the pyrolysis process has high requirements for continuous heating and temperature stability. Fluctuations in heating can lead to unstable product yields and exacerbate secondary tar reactions.

[0003] Solar energy, as a clean and renewable heat source, can be used to provide energy for biomass pyrolysis. However, solar energy is significantly intermittent and fluctuating, affected by factors such as day-night cycles and weather changes, making it difficult to directly meet the continuous operation requirements of pyrolysis reactors. Existing solar pyrolysis systems typically use electric heating or fossil fuel-assisted heating, increasing system complexity and operating costs, and diminishing environmental benefits. Summary of the Invention

[0004] Objective: In order to overcome the shortcomings of the existing technology, the present invention provides a solar-driven continuous biomass pyrolysis system and method based on thermochemical thermal storage.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows: In a first aspect, a solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage is provided, comprising: A solar thermal collector unit is used to collect solar radiation energy and convert it into heat energy; The biomass pyrolysis reaction unit is equipped with a biomass inlet and a product outlet for the pyrolysis and recovery of biomass. The thermochemical thermal storage unit is equipped with a CO2 inlet and a CO2 outlet, and is filled with thermochemical thermal storage material with MgO / MgCO3 as the active component. The thermochemical thermal storage unit exchanges heat with the solar thermal collector unit and the biomass pyrolysis reaction unit through heat exchange medium circulation pipelines. The CO2 recycling subsystem is used to supply CO2 to the thermochemical storage unit to participate in the exothermic reaction and to recover the discharged CO2 for recycling. The control system is electrically connected to the solar thermal collector, biomass pyrolysis reaction unit, thermochemical thermal storage unit, and CO2 circulation subsystem. It is used to acquire solar irradiance, internal temperature of biomass pyrolysis reaction unit, internal temperature of thermochemical thermal storage unit, and CO2 flow rate, and automatically adjust the operating mode and heat exchange medium flow rate according to preset parameters.

[0006] The solution provided by this invention utilizes MgO / MgCO3 thermochemical heat storage material as an energy storage medium. When solar energy is abundant, excess heat is stored in the form of chemical energy. When solar energy is insufficient or at night, heat is released through carbonation reaction, providing a continuous and stable heat source for the biomass pyrolysis reaction unit. This overcomes the intermittent nature of solar energy and enables continuous operation of biomass pyrolysis around the clock.

[0007] In some embodiments, the solar collector unit is selected from at least one of a parabolic trough collector, a linear Fresnel collector, and a tower heliostat system.

[0008] In some embodiments, the thermochemical thermal storage unit is provided with a first heating jacket; In the connection path between the solar collector unit and the first heating jacket in the heat exchange medium circulation pipeline, a first flow regulating valve and a circulation pump are provided on the path from the solar collector unit to the first heating jacket; a second flow regulating valve is provided on the path from the first heating jacket to the solar collector unit; the flow rate of the heat exchange medium is adjusted to facilitate the absorption or release of heat, and to regulate the internal temperature of the thermochemical heat storage unit and the biomass pyrolysis reaction unit.

[0009] In some embodiments, the CO2 inlet is also connected to a gas distributor, which facilitates the uniform distribution of CO2 into the thermochemical thermal storage unit.

[0010] In some embodiments, the thermochemical thermal storage unit is further provided with a first insulation layer on its outer periphery.

[0011] In some embodiments, the internal structure of the thermochemical thermal storage unit is a fixed bed, a fluidized bed, or a moving bed to enhance heat and mass transfer efficiency.

[0012] In some embodiments, the biomass pyrolysis reaction unit is provided with a second heating jacket; the second heating jacket is connected to the first heating jacket through a heat exchange medium circulation pipeline; a first flow meter is provided on the connection path of the heat exchange medium flowing from the first heating jacket to the second heating jacket; the flow rate of the heat exchange medium is monitored in real time, thereby regulating the internal temperature of the biomass pyrolysis reaction unit.

[0013] In some embodiments, the product outlet includes a bio-oil outlet, a pyrolysis gas outlet, and a biochar outlet; In some embodiments, a nitrogen inlet is provided on the side of the biomass feed inlet; In some embodiments, a second heat insulation layer is provided on the outer periphery of the biomass pyrolysis reaction unit.

[0014] In some embodiments, the solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage further includes a waste heat recovery unit electrically connected to the control system to obtain the temperature of the waste heat recovery unit; the waste heat recovery unit is provided with a nitrogen passage and a pyrolysis gas passage; the nitrogen passage is connected to the nitrogen inlet, and the pyrolysis gas passage is connected to the pyrolysis gas outlet, for recovering the heat energy carried by the pyrolysis gas to preheat the nitrogen entering the biomass pyrolysis reaction unit.

[0015] In some embodiments, the thermochemical storage material filling the thermochemical storage unit further includes a framework support phase material and a thermally conductive enhancement phase material; The framework support phase material is selected from at least one of MnO2, Co3O4, Fe2O3 and Al2O3, and the thermally conductive enhancement phase material is selected from at least one of graphite and silicon carbide.

[0016] In some embodiments, the CO2 circulation subsystem includes a CO2 storage tank, a compressor, and a condenser; the CO2 outlet of the thermochemical thermal storage unit is connected to the CO2 storage tank inlet via a CO2 gas path, with a compressor installed along the connection path; the CO2 storage tank outlet is connected to the CO2 inlet of the thermochemical thermal storage unit via a CO2 gas path, with a condenser installed along the connection path; the CO2 circulation subsystem achieves closed-loop utilization of the gas, reducing gas consumption and emissions. In some embodiments, a second flow meter and a pressure gauge are provided on the connection path between the CO2 storage tank outlet and the condenser.

[0017] In some embodiments, the heat exchange medium is molten salt with an operating temperature of 200~600℃; the circulation pipeline can be an electrically heated insulated pipeline with a maximum operating temperature of 300℃ to ensure that the molten salt is in the liquid phase; indirect heat exchange is used to avoid mutual interference between CO2 in the thermochemical heat storage unit and nitrogen in the biomass pyrolysis reaction unit.

[0018] In some embodiments, the pyrolysis reaction temperature in the biomass pyrolysis reaction unit and the operating temperature of the thermochemical thermal storage unit are both 300~500℃.

[0019] In some embodiments, the operating modes include energy storage mode, heat release mode, and synchronization mode; Among them, the energy storage mode is suitable for solar irradiance ≥600W / m 2 Furthermore, it is activated when the temperature inside the biomass pyrolysis reaction unit is ≥500℃, and is used to store the heat energy collected by the solar collector unit into the thermochemical heat storage unit for subsequent use; this mode is used to store excess energy for subsequent use when solar energy is sufficient. Exothermic mode at solar irradiance ≤400W / m 2It can be activated when the temperature inside the biomass pyrolysis reactor is ≤300℃, and is used to transfer the thermal energy stored in the thermochemical thermal storage unit to the biomass pyrolysis reactor to maintain the pyrolysis reaction temperature inside the biomass pyrolysis reactor; this mode is used to provide a continuous and stable heat source when solar energy is insufficient. Synchronous mode at solar irradiance ≥600W / m 2 Furthermore, the system is activated when the temperature inside the biomass pyrolysis reaction unit is ≤500℃. This system first supplies the heat energy collected by the solar collector to the biomass pyrolysis reaction unit to ensure the pyrolysis reaction proceeds, and then supplies the remaining heat energy to the thermochemical storage unit for storage. This mode enables the simultaneous utilization and storage of solar energy.

[0020] In a second aspect, a method for continuous pyrolysis of biomass based on thermochemical thermal storage, using a solar-driven biomass pyrolysis system based on thermochemical thermal storage as described in any one of the first aspects, is provided, comprising: The control system first preheats the heat exchange medium until it is in the liquid phase and has fluidity, then starts the circulation of the heat exchange medium. Preset parameters, including a first threshold of 600 W / m² solar irradiance. 2 The second threshold is a solar irradiance of 400 W / m². 2 The upper limit of the temperature in the biomass pyrolysis reaction unit is 500℃, and the lower limit of the temperature is 300℃. The operating temperature of the thermochemical thermal storage unit is 300~500℃. The solar irradiance intensity, the internal temperature of the biomass pyrolysis reaction unit, the internal temperature of the thermochemical thermal storage unit, and the CO2 flow rate were obtained. Adjusting the operating mode and heat exchange medium flow rate according to preset parameters includes the following steps: When solar irradiance intensity is detected to be ≥600 W / m 2 Furthermore, when the internal temperature of the biomass pyrolysis reactor reaches ≥500℃, the control system enters energy storage mode. The energy storage mode execution steps include: Turn on the circulation pump and close the CO2 inlet of the thermochemical thermal storage unit. The heat energy collected by the solar thermal collector is transferred to the thermochemical thermal storage unit through the heat exchange medium. The internal temperature of the thermochemical thermal storage unit rises, driving the decomposition of MgCO3 to generate MgO and CO2. The heat energy is stored in the thermochemical thermal storage unit in the form of chemical energy. The CO2 enters the CO2 storage tank through the CO2 outlet for subsequent use. The heat exchange medium carries the remaining heat energy to the biomass pyrolysis reaction unit to keep the pyrolysis reaction warm. When the detected solar irradiance intensity is ≤400W / m 2 When the internal temperature of the biomass pyrolysis reaction unit is ≤300℃, the control system enters the exothermic mode. The exothermic mode execution steps include: When the CO2 inlet and circulation pump are turned on, the CO2 in the CO2 storage tank enters the thermochemical heat storage unit after being dehydrated by the condenser. It reacts with MgO to generate MgCO3 and releases heat energy. The remaining CO2 that does not participate in the reaction is discharged from the CO2 outlet and returned to the CO2 storage tank. The released heat energy is transferred to the biomass pyrolysis reaction unit through the heat exchange medium, providing a heat source for the pyrolysis reaction; the control system adjusts the CO2 flow rate and the heat exchange medium flow rate according to the internal temperature of the biomass pyrolysis reaction unit. When solar irradiance intensity is detected to be ≥600 W / m 2 Furthermore, when the internal temperature of the biomass pyrolysis reaction unit is ≤500℃, the control system enters synchronization mode. The synchronization mode execution steps include: Turn on the circulation pump and close the CO2 inlet; the heat energy collected by the solar thermal collector flows through the biomass pyrolysis reaction unit through the heat exchange medium to provide a heat source for the pyrolysis reaction, and then carries the remaining heat energy to the thermochemical thermal storage unit to drive the decomposition of MgCO3 to generate MgO and CO2. The heat energy is stored in the thermochemical thermal storage unit in the form of chemical energy; the CO2 enters the CO2 storage tank through the CO2 outlet for subsequent use.

[0021] The control system automatically and seamlessly switches between the three modes based on real-time data collected from solar irradiance, the internal temperature of the biomass pyrolysis reactor, the internal temperature of the thermochemical thermal storage unit, and CO2 flow rate, ensuring that the biomass pyrolysis reactor can obtain a continuous and stable heat supply under any conditions.

[0022] When the system switches from energy storage mode or synchronous mode to heat release mode, the control system first opens the CO2 inlet and starts the CO2 circulation subsystem. After the thermochemical heat storage unit starts to release heat, the flow rate of the heat exchange medium is adjusted as needed. When the system switches from heat release mode to energy storage mode or synchronous mode, the control system first shuts down the CO2 inlet and the CO2 circulation subsystem, and then proceeds with subsequent operations after the solar thermal collectors start supplying heat.

[0023] Beneficial effects: The solar-driven continuous biomass pyrolysis system and method based on thermochemical thermal storage provided by this invention have the following advantages: 1. By utilizing the energy storage and heat release functions of the thermochemical thermal storage unit, unstable solar energy is converted into chemical energy for storage and released stably as thermal energy when needed, providing a continuous and controllable heat source for biomass pyrolysis, overcoming the intermittent nature of solar energy and enabling all-weather operation; 2. The operating temperature range (300~500℃) of the MgO / MgCO3 thermochemical thermal storage system highly overlaps with the main reaction temperature range (300~500℃) of biomass pyrolysis, eliminating the need for additional temperature zone conversion equipment, reducing heat loss, and improving system thermal efficiency; 3. The closed-loop utilization of reaction gases is achieved through the CO2 circulation subsystem, reducing gas consumption and emissions; the indirect heat exchange method effectively avoids cross-interference between the CO2 atmosphere in the heat storage unit and the inert atmosphere in the biomass pyrolysis reaction unit, ensuring the quality of pyrolysis products. 4. The system can automatically switch between three modes—energy storage, heat release, and synchronization—based on solar irradiance and pyrolysis requirements, thereby optimizing energy allocation in time and space and improving solar energy utilization efficiency. 5. The system uses solar energy as the main heat source and utilizes biomass waste for pyrolysis to achieve a carbon-negative emission process driven by renewable energy, which has good environmental and economic benefits. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of a solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage, according to an embodiment of the present invention.

[0025] Reference numerals: 1. Solar collector unit; 2. Thermochemical storage unit; 3. Biomass pyrolysis reaction unit; 4. Control system; 5. CO2 inlet; 6. CO2 outlet; 7. First heating jacket; 8. First flow regulating valve; 9. Circulation pump; 10. Second flow regulating valve; 11. Gas distributor; 12. First insulation layer; 13. Second heating jacket; 14. First flow meter; 15. Bio-oil outlet; 16. Pyrolysis gas outlet; 17. Biochar outlet; 18. Biomass inlet; 19. Second insulation layer; 20. Waste heat recovery unit; 21. CO2 storage tank; 22. Compressor; 23. Condenser; 24. Second flow meter; 25. Pressure gauge; 26. Nitrogen inlet. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below 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 protection scope of the present invention.

[0027] The present invention will be further described below with reference to specific embodiments.

[0028] Example 1: As Figure 1 As shown, the various components of this system are physically connected through pipes, flanges, valves, and sensors, as detailed below: Solar thermal collector unit 1 is used to collect solar radiation energy and convert it into heat energy; The biomass pyrolysis reaction unit 3 is equipped with a biomass inlet 18 and a product outlet, and is used for the pyrolysis and recovery of biomass. The thermochemical thermal storage unit 2 is equipped with a CO2 inlet 5 and a CO2 outlet 6, and is filled with thermochemical thermal storage material with MgO / MgCO3 as the active component. The thermochemical thermal storage unit 2 exchanges heat with the solar thermal collector unit 1 and the biomass pyrolysis reaction unit 3 through heat exchange medium circulation pipelines. The CO2 recycling subsystem is used to supply CO2 to the thermochemical thermal storage unit 2 to participate in the exothermic reaction and to recover the discharged CO2 for recycling. The control system 4 is electrically connected to the solar thermal collector unit 1, the biomass pyrolysis reaction unit 3, the thermochemical thermal storage unit 2, and the CO2 circulation subsystem. It is used to acquire solar irradiance, the internal temperature of the biomass pyrolysis reaction unit 3, the internal temperature of the thermochemical thermal storage unit 2, and the CO2 flow rate, and automatically adjust the operating mode and heat exchange medium flow rate according to preset parameters. In this embodiment, the heat exchange medium is molten salt with an operating temperature of 200~600℃; the biomass pyrolysis reaction unit 3 uses a biomass pyrolysis reactor; the pyrolysis reaction temperature and the operating temperature of the thermochemical thermal storage unit 2 are both 300~500℃.

[0029] The solar collector unit 1 is selected from a parabolic trough collector.

[0030] The thermochemical thermal storage unit 2 is a vertical fixed-bed reactor. The upper and lower ends of the shell are respectively welded with molten salt inlet and outlet first heating jackets 7. The top of the shell is provided with CO2 inlet 5 and connected to gas distributor 11. Gas distributor 11 is a porous plate structure and is connected to CO2 gas path through flange. The bottom of the shell is provided with CO2 outlet 6 and connected to CO2 gas path through flange. The interior is filled with MgO / MgCO3 particles with a particle diameter of about 2~5mm. In addition, it also includes skeleton support phase material and thermally conductive reinforcing phase material. The skeleton support phase material is selected from Co3O4, and the thermally conductive reinforcing phase material is selected from graphite. The shell is covered with a first insulation layer 12.

[0031] The outlet of CO2 storage tank 21 is connected to the inlet of condenser 23 via a flange. The outlet of condenser 23, after passing through a gas-liquid separator, is connected to the CO2 inlet 5 at the top of thermochemical thermal storage unit 2 via a flange. The bottom CO2 outlet 6 is connected to compressor 22 via a flange. The outlet of compressor 22 is connected to CO2 storage tank 21 via a flange, forming a closed loop. A pressure gauge 25 and a second flow meter 24 are installed on the pipeline at the outlet of CO2 storage tank 21.

[0032] The biomass pyrolysis reactor is a horizontal screw propulsion structure. A second heating jacket 13 is welded to the outside of the reactor cylinder. One end of the reactor is provided with a biomass inlet 18, and a hopper and screw feeder are provided above it. A nitrogen inlet is provided next to the biomass inlet 18. The other end of the reactor is provided with pyrolysis product outlets, including a bio-oil outlet 15, a pyrolysis gas outlet 16, and a biochar outlet 17. The outer periphery is covered with a second insulation layer 19.

[0033] The receiving pipes of the solar collector are connected to the molten salt circulation pipeline through flanges at both ends. The molten salt is driven by the circulation pump 9 to flow sequentially through the solar collector, the first heating jacket 7 of the thermochemical heat storage unit 2 and the second heating jacket 13 of the biomass pyrolysis reactor, and then returns to the solar collector, forming a closed circulation loop. Each section of the pipeline is equipped with a shut-off valve and a temperature sensor. In the connection path between the solar collector unit 1 and the first heating jacket 7, a first flow regulating valve 8 and a circulation pump 9 are provided on the path from the solar collector unit 1 to the first heating jacket 7; a second flow regulating valve 10 is provided on the path from the first heating jacket 7 to the solar collector unit 1; and a first flow meter 14 is provided on the connection path from the first heating jacket 7 to the second heating jacket 13.

[0034] Waste heat recovery unit 20 is electrically connected to control system 4 to obtain the temperature of waste heat recovery unit 20; it is installed on the pyrolysis gas outlet 16 pipeline of biomass pyrolysis reactor and adopts shell and tube heat exchanger structure, with pyrolysis gas flowing through the shell side and nitrogen flowing through the tube side. The nitrogen outlet is connected to the nitrogen inlet 26 of biomass pyrolysis reactor through flange to realize the preheating of nitrogen.

[0035] The operating modes include energy storage mode, heat release mode, and synchronization mode; Among them, the energy storage mode is suitable for solar irradiance ≥600W / m 2 Furthermore, the biomass pyrolysis reaction unit 3 is activated when the temperature inside reaches ≥500℃, and is used to store the thermal energy collected by the solar collector unit 1 into the thermochemical thermal storage unit 2 for subsequent use; this mode is used to store excess energy for subsequent use when solar energy is sufficient. Exothermic mode at solar irradiance ≤400W / m 2 It can be activated when the temperature inside the biomass pyrolysis reaction unit 3 is ≤300℃, and is used to transfer the thermal energy stored in the thermochemical thermal storage unit 2 to the biomass pyrolysis reaction unit 3 to maintain the pyrolysis reaction temperature inside the biomass pyrolysis reaction unit 3; this mode is used to provide a continuous and stable heat source when solar energy is insufficient. Synchronous mode at solar irradiance ≥600W / m 2 Furthermore, the system is activated when the temperature inside the biomass pyrolysis reaction unit 3 is ≤500℃. This system first supplies the heat energy collected by the solar collector unit 1 to the biomass pyrolysis reaction unit 3 to ensure the pyrolysis reaction proceeds, and then supplies the remaining heat energy to the thermochemical heat storage unit 2 for storage. This mode enables the simultaneous utilization and storage of solar energy.

[0036] Example 2: This example provides a solar-driven continuous biomass pyrolysis method based on thermochemical thermal storage, including: The control system 4 first preheats the heat exchange medium until it is in the liquid phase and has fluidity, and then starts the circulation of the heat exchange medium. Preset parameters, including a first threshold of 600 W / m² solar irradiance. 2 The second threshold is a solar irradiance of 400 W / m². 2 The upper limit of the temperature in biomass pyrolysis reaction unit 3 is 500℃, and the lower limit of the temperature is 300℃. The working temperature of thermochemical heat storage unit 2 is 300~500℃. The solar irradiance intensity, the internal temperature of biomass pyrolysis reaction unit 3, the internal temperature of thermochemical thermal storage unit 2, and the CO2 flow rate were obtained. Adjusting the operating mode and heat exchange medium flow rate according to preset parameters includes the following steps: When solar irradiance intensity is detected to be ≥600 W / m 2 Furthermore, when the internal temperature of biomass pyrolysis reaction unit 3 is ≥500℃, control system 4 enters energy storage mode. The energy storage mode execution steps include: Turn on the circulation pump 9 and close the CO2 inlet 5 of the thermochemical thermal storage unit 2. The heat energy collected by the solar thermal collector 1 is transferred to the thermochemical thermal storage unit 2 through the heat exchange medium. The internal temperature of the thermochemical thermal storage unit 2 rises, driving the decomposition of MgCO3 to generate MgO and CO2. The heat energy is stored in the thermochemical thermal storage unit 2 in the form of chemical energy. The CO2 enters the CO2 storage tank 21 through the CO2 outlet 6 for storage and subsequent use. The heat exchange medium carries the remaining heat energy to the biomass pyrolysis reaction unit 3 to keep the pyrolysis reaction warm. When the detected solar irradiance intensity is ≤400W / m 2 When the internal temperature of biomass pyrolysis reaction unit 3 is ≤300℃, control system 4 enters exothermic mode. The exothermic mode execution steps include: When the CO2 inlet 5 and circulation pump 9 are turned on, the CO2 in the CO2 storage tank 21 enters the thermochemical heat storage unit 2 after being dehydrated by the condenser 23. It reacts with MgO to generate MgCO3 and releases heat energy. The remaining CO2 that does not participate in the reaction is discharged from the CO2 outlet 6 and returned to the CO2 storage tank 21. The released heat energy is transferred to the biomass pyrolysis reaction unit 3 through the heat exchange medium, providing a heat source for the pyrolysis reaction; the control system 4 adjusts the CO2 flow rate and the heat exchange medium flow rate according to the internal temperature of the biomass pyrolysis reaction unit 3. When solar irradiance intensity is detected to be ≥600 W / m 2 When the internal temperature of biomass pyrolysis reaction unit 3 is ≤500℃, control system 4 enters synchronization mode. The synchronization mode execution steps include: Turn on the circulation pump 9 and close the CO2 inlet 5; the heat energy collected by the solar collector unit 1 flows through the biomass pyrolysis reaction unit 3 through the heat exchange medium to provide a heat source for the pyrolysis reaction, and then carries the remaining heat energy to the thermochemical heat storage unit 2 to drive the decomposition of MgCO3 to generate MgO and CO2. The heat energy is stored in the thermochemical heat storage unit 2 in the form of chemical energy; CO2 enters the CO2 storage tank 21 through the CO2 outlet 6 for storage and subsequent use.

[0037] The control system 4 automatically and seamlessly switches between the three modes based on the real-time collected solar irradiance, the internal temperature of the biomass pyrolysis reaction unit 3, the internal temperature of the thermochemical heat storage unit 2, and the CO2 flow rate, ensuring that the biomass pyrolysis reaction unit 3 can obtain a continuous and stable heat supply under any conditions.

[0038] When the system switches from energy storage mode or synchronous mode to heat release mode, the control system 4 first opens CO2 inlet 5 and starts CO2 circulation subsystem. After the thermochemical heat storage unit 2 starts to release heat, the flow rate of heat exchange medium is adjusted as needed. When the system switches from heat release mode to energy storage mode or synchronous mode, the control system 4 first shuts down the CO2 inlet 5 and the CO2 circulation subsystem, and then proceeds with subsequent operations after the solar thermal collector unit 1 starts supplying heat.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage, characterized in that, include: A solar thermal collector unit (1) is used to collect solar radiation energy and convert it into thermal energy; The biomass pyrolysis reaction unit (3) is equipped with a biomass inlet (18) and a product outlet for the pyrolysis and recovery of biomass. The thermochemical heat storage unit (2) is equipped with a CO2 inlet (5) and a CO2 outlet (6), and is filled with thermochemical heat storage material with MgO / MgCO3 as the active component. The thermochemical heat storage unit (2) exchanges heat with the solar heat collection unit (1) and the biomass pyrolysis reaction unit (3) through heat exchange medium circulation pipelines. The CO2 recycling subsystem is used to provide CO2 that participates in the exothermic reaction to the thermochemical thermal storage unit (2) and to recover the discharged CO2 for recycling. The control system (4) is electrically connected to the solar thermal collector (1), the biomass pyrolysis reaction unit (3), the thermochemical thermal storage unit (2) and the CO2 circulation subsystem. It is used to obtain the solar irradiance, the internal temperature of the biomass pyrolysis reaction unit (3), the internal temperature of the thermochemical thermal storage unit (2) and the CO2 flow rate, and automatically adjust the operation mode and the flow rate of the heat exchange medium according to the preset parameters.

2. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 1, characterized in that, The solar collector unit (1) is selected from at least one of a parabolic trough collector, a linear Fresnel collector, and a tower heliostat system.

3. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 1, characterized in that, The thermochemical heat storage unit (2) is provided with a first heating jacket (7); In the connection path between the solar collector unit (1) and the first heating jacket (7) in the heat exchange medium circulation pipeline, a first flow regulating valve (8) and a circulation pump (9) are provided on the path of the heat exchange medium flowing from the solar collector unit (1) to the first heating jacket (7); a second flow regulating valve (10) is provided on the path of the heat exchange medium flowing from the first heating jacket (7) to the solar collector unit (1). And / or, the CO2 inlet (5) is also connected to a gas distributor (11); And / or, the thermochemical thermal storage unit (2) is further provided with a first insulation layer (12) on its outer periphery.

4. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 3, characterized in that, The biomass pyrolysis reaction unit (3) is provided with a second heating jacket (13); the second heating jacket (13) is connected to the first heating jacket (7) through a heat exchange medium circulation pipeline; a first flow meter (14) is provided on the connection path of the heat exchange medium flowing from the first heating jacket (7) to the second heating jacket (13); And / or, the product outlets include a bio-oil outlet (15), a pyrolysis gas outlet (16), and a biochar outlet (17). And / or, a nitrogen inlet (26) is provided on the side of the biomass feed inlet (18); And / or, the outer periphery of the biomass pyrolysis reaction unit (3) is also provided with a second heat insulation layer (19).

5. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 4, characterized in that, The solar-driven continuous pyrolysis system based on thermochemical thermal storage also includes a waste heat recovery unit (20), which is electrically connected to the control system (4). The waste heat recovery unit (20) is provided with a nitrogen passage and a pyrolysis gas passage. The nitrogen passage is connected to the nitrogen inlet (26), and the pyrolysis gas passage is connected to the pyrolysis gas outlet (16) to recover the heat energy carried by the pyrolysis gas in order to preheat the nitrogen entering the biomass pyrolysis reaction unit (3).

6. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 1, characterized in that, The thermochemical thermal storage unit (2) is filled with a thermochemical thermal storage material that also includes a skeleton support phase material and a thermally conductive enhancement phase material. The framework support phase material is selected from at least one of MnO2, Co3O4, Fe2O3 and Al2O3, and the thermally conductive enhancement phase material is selected from at least one of graphite and silicon carbide.

7. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 1, characterized in that, The CO2 circulation subsystem includes a CO2 storage tank (21), a compressor (22), and a condenser (23); the CO2 outlet (6) of the thermochemical thermal storage unit (2) is connected to the inlet of the CO2 storage tank (21) through a CO2 gas path, and a compressor (22) is installed on the connection path; the outlet of the CO2 storage tank (21) is connected to the CO2 inlet (5) of the thermochemical thermal storage unit (2) through a CO2 gas path, and a condenser (23) is installed on the connection path. And / or, a second flow meter (24) and a pressure gauge (25) are provided on the connection path between the outlet of the CO2 storage tank (21) and the condenser (23).

8. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 1, characterized in that, The heat exchange medium is molten salt, and the operating temperature is 200~600℃; And / or, the pyrolysis reaction temperature in the biomass pyrolysis reaction unit (3) and the operating temperature of the thermochemical heat storage unit (2) are both 300~500℃.

9. The solar-driven continuous biomass pyrolysis system based on thermochemical thermal storage according to claim 1, characterized in that, The operating modes include energy storage mode, heat release mode, and synchronization mode; Among them, the energy storage mode is suitable for solar irradiance ≥600W / m 2 The biomass pyrolysis reaction unit (3) is activated when the temperature inside is ≥500℃, and is used to store the heat energy collected by the solar thermal collector (1) into the thermochemical thermal storage unit (2) for subsequent use. Exothermic mode at solar irradiance ≤400W / m 2 It can be started when the temperature inside the biomass pyrolysis reaction unit (3) is ≤300℃, and is used to transfer the heat energy stored in the thermochemical heat storage unit (2) to the biomass pyrolysis reaction unit (3) to maintain the pyrolysis reaction temperature inside the biomass pyrolysis reaction unit (3); Synchronous mode at solar irradiance ≥600W / m 2 The biomass pyrolysis reaction unit (3) is activated when the temperature inside is ≤500℃. It is used to provide the heat energy collected by the solar collector unit (1) to the biomass pyrolysis reaction unit (3) to ensure the pyrolysis reaction. The remaining heat energy is then provided to the thermochemical heat storage unit (2) for storage.

10. A method for continuous solar-driven biomass pyrolysis based on thermochemical thermal storage, according to any one of claims 1 to 9, characterized in that, include: The control system (4) first preheats the heat exchange medium until it is in the liquid phase and has fluidity, and then starts the heat exchange medium circulation. Preset parameters, including a first threshold of 600 W / m² solar irradiance. 2 The second threshold is a solar irradiance of 400 W / m². 2 The upper limit of the temperature in the biomass pyrolysis reaction unit (3) is 500℃, the lower limit of the temperature is 300℃, and the working temperature of the thermochemical heat storage unit (2) is 300~500℃. The solar irradiance intensity, the internal temperature of the biomass pyrolysis reaction unit (3), the internal temperature of the thermochemical thermal storage unit (2), and the CO2 flow rate were obtained. Adjusting the operating mode and heat exchange medium flow rate according to preset parameters includes the following steps: When solar irradiance intensity is detected to be ≥600 W / m 2 Furthermore, when the internal temperature of the biomass pyrolysis reaction unit (3) is ≥500℃, the control system (4) enters the energy storage mode. The energy storage mode execution steps include: Turn on the circulation pump (9), close the CO2 inlet (5) of the thermochemical thermal storage unit (2), and transfer the heat energy collected by the solar thermal collector (1) to the thermochemical thermal storage unit (2) through the heat exchange medium. The internal temperature of the thermochemical thermal storage unit (2) rises, driving the decomposition of MgCO3 to generate MgO and CO2. The heat energy is stored in the thermochemical thermal storage unit (2) in the form of chemical energy. CO2 enters the CO2 storage tank (21) through the CO2 outlet (6) for storage for subsequent use. The heat exchange medium carries the remaining heat energy to the biomass pyrolysis reaction unit (3) to keep the pyrolysis reaction warm; When the detected solar irradiance intensity is ≤400W / m 2 When the internal temperature of the biomass pyrolysis reaction unit (3) is ≤300℃, the control system (4) enters the exothermic mode. The exothermic mode execution steps include: Turn on the CO2 inlet (5) and the circulation pump (9). After the CO2 in the CO2 storage tank (21) is dehydrated by the condenser (23), it enters the thermochemical heat storage unit (2), reacts with MgO to generate MgCO3 and releases heat energy; the remaining CO2 that does not participate in the reaction is discharged from the CO2 outlet (6) and returned to the CO2 storage tank (21). The released heat energy is transferred to the biomass pyrolysis reaction unit (3) through the heat exchange medium to provide a heat source for the pyrolysis reaction; the control system (4) adjusts the CO2 flow rate and the heat exchange medium flow rate according to the internal temperature of the biomass pyrolysis reaction unit (3); When solar irradiance intensity is detected to be ≥600 W / m 2 When the internal temperature of the biomass pyrolysis reaction unit (3) is ≤500℃, the control system (4) enters the synchronization mode. The synchronization mode execution steps include: Turn on the circulation pump (9) and close the CO2 inlet (5); the heat energy collected by the solar thermal collector (1) flows through the biomass pyrolysis reaction unit (3) through the heat exchange medium to provide a heat source for the pyrolysis reaction, and then carries the remaining heat energy to the thermochemical thermal storage unit (2) to drive the decomposition of MgCO3 to generate MgO and CO2. The heat energy is stored in the thermochemical thermal storage unit (2) in the form of chemical energy; CO2 enters the CO2 storage tank (21) through the CO2 outlet (6) for storage for subsequent use.

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