A system for solar-driven pyrolysis product desulfurization and sulfur-doped carbon material cascade

Abstract

The present application belongs to the technical field of waste tire pyrolysis and carbon material cascade sulfur doping, and particularly relates to a system for pyrolysis product desulfurization and carbon material cascade sulfur doping driven by solar energy, which is heated by a pyrolysis furnace and a solar heat collecting mechanism, and pyrolysis oil gas is sent into a fixed bed-fluidized bed coupling mechanism through a flue gas conveying pipeline to realize online desulfurization of the pyrolysis oil gas and reduce the sulfur content of the product; the fixed bed-fluidized bed coupling mechanism cooperates with a fixed bed screening combination mechanism to convert sulfur pollutants into modified components; the fixed bed screening combination mechanism exchanges heat with the flue gas conveying pipeline to recover flue gas waste heat, and purified oil gas is stored in a gas tank after being used for secondary waste heat recovery by a seawater desalination mechanism; the seawater desalination mechanism provides modified conditions for a carbon black collecting tank to ensure the desulfurization and sulfur doping effects; and a molten salt circulation and regeneration mechanism connects the pyrolysis furnace and the fixed bed screening combination mechanism to realize molten salt circulation and regeneration and reduce secondary solid waste.

Description

Technical Field

[0001] This invention belongs to the field of waste tire pyrolysis and carbon material cascade sulfur doping technology, and particularly relates to a solar-driven system for pyrolysis product desulfurization and cascade sulfur doping of carbon materials. Background Technology

[0002] With the increasing global demand for solid waste management and renewable energy utilization, the harmless and high-value treatment of waste tires, as a typical recalcitrant industrial solid waste, has become a key research direction in the industry. Pyrolysis technology can convert waste tires into high-value-added products such as pyrolysis oil, carbon black, and combustible gas, and is currently the mainstream resource utilization method.

[0003] Dish solar concentrator technology features high concentration ratio, high heat conversion efficiency, and a wide range of heating temperatures, providing a clean heat source for the pyrolysis process and replacing traditional fossil fuels.

[0004] Existing waste tire pyrolysis treatment technologies have several prominent drawbacks. Traditional pyrolysis systems are highly dependent on fossil fuels such as natural gas and electricity, resulting in high energy costs and large carbon emissions. Waste tires themselves have a high sulfur content, leading to excessive sulfur pollutants in the pyrolysis products, making subsequent desulfurization processes complex and costly. Conventional desulfurization technologies can only remove gaseous sulfides and cannot utilize sulfur pollutants as resources. Desulfurizing agents are difficult to regenerate and easily generate secondary solid waste. At the same time, pyrolysis carbon black can only be used as a low-end filler with extremely low added value. The systems are mostly simple unit splicing with low integration, failing to form a continuous closed-loop operation system, resulting in insufficient energy cascade utilization, low overall energy efficiency, and difficulty in balancing cleanliness and economy. Summary of the Invention

[0005] The purpose of this invention is to provide a solar-driven system for the desulfurization of pyrolysis products and the cascaded sulfur doping of carbon materials to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following solution: A solar-driven system for synergistic desulfurization of pyrolysis products and cascade sulfur doping with carbon materials includes: a pyrolysis furnace, wherein the pyrolysis furnace has an inner cavity and a spiral flow channel, the spiral flow channel being connected to a solar thermal concentrator; a carbon black collection tank is connected to the inner cavity of the pyrolysis furnace; the inner cavity of the pyrolysis furnace is connected via a flue gas conveying pipe to a fixed-bed-fluidized-bed coupling mechanism for fluidized-bed desulfurization and preliminary sulfur doping of pyrolysis oil and gas; modified biochar and a highly active sulfur-fixing agent are disposed within the fixed-bed-fluidized-bed coupling mechanism; and a device for achieving fixed-bed desulfurization is connected below the fixed-bed-fluidized-bed coupling mechanism. A fixed-bed screening mechanism combining molten salt sulfur transfer and deep sulfur doping with biochar is provided. The fixed-bed screening mechanism is heat-exchange connected to the flue gas conveying pipeline. A gas holder is connected to the fixed-bed-fluidized-bed coupling mechanism. A seawater desalination mechanism is heat-exchange connected between the gas holder and the fixed-bed-fluidized-bed coupling mechanism. The seawater desalination mechanism is connected to the carbon black collection tank for functional group modification of the carbon black. A molten salt circulation and regeneration mechanism is heat-exchange connected between the pyrolysis furnace and the fixed-bed screening mechanism.

[0007] The system is heated by a solar thermal concentrator in conjunction with the inner cavity of the pyrolysis furnace and a spiral flow channel. The carbon black produced by the pyrolysis furnace enters the carbon black collection tank, and the pyrolysis oil and gas enter the fixed bed-fluidized bed coupling mechanism through the flue gas conveying pipeline. Under the action of modified biochar and highly active sulfur-fixing agent, fluidized bed desulfurization and preliminary sulfur doping are completed. The fixed bed screening and combination mechanism below the coupling mechanism realizes molten salt sulfur transfer and deep sulfur doping of biochar. The flue gas conveying pipeline and the fixed bed screening and combination mechanism exchange heat. The purified oil and gas output from the coupling mechanism enters the gas holder after the waste heat of the seawater desalination mechanism is utilized. The seawater desalination mechanism provides functional group modification conditions for the carbon black collection tank and is connected to the molten salt circulation and regeneration mechanism to realize the circulation and regeneration of molten salt between the pyrolysis furnace and the fixed bed screening and combination mechanism. The whole system completes the coordinated operation of desulfurization, sulfur doping, energy recovery and material circulation.

[0008] The system provides heat through a solar thermal concentrator that works in conjunction with the inner cavity of the pyrolysis furnace and the spiral flow channel. The solar thermal concentrator includes a solar concentrator used to heat the molten salt storage tank. The molten salt storage tank is connected to the spiral flow channel through a first conveying pipe. The fixed bed screening mechanism is connected to the spiral flow channel through a second conveying pipe.

[0009] The solar thermal concentrator heats the molten salt storage tank with a solar concentrator. The molten salt enters the spiral flow channel of the pyrolysis furnace through the first conveying pipe, and returns to the molten salt storage tank after heat exchange. The molten salt of the fixed bed screening and combination mechanism flows to the regeneration tank through the second conveying pipe, forming two independent molten salt circulation loops to ensure stable operation of heating and heat replenishment.

[0010] In the solar-driven pyrolysis product desulfurization and cascade sulfur doping system of the present invention, a carbon black screen is provided in the fixed bed screening mechanism, the carbon black screen is located above the molten salt, a molten salt inlet is provided on one side of the fixed bed screening mechanism, the molten salt inlet is located above the screen, a solid phase falling channel is opened at the top of the fixed bed screening mechanism, the solid phase falling channel is connected to the fixed bed-fluidized bed coupling mechanism, and the flue gas conveying pipe sequentially passes through the molten salt, the screen and the top of the fixed bed screening mechanism and then extends into the fixed bed-fluidized bed coupling mechanism.

[0011] The fixed bed screening mechanism is equipped with a carbon black screening screen and a screen. The molten salt inlet is located above the screen. The top is equipped with a solid phase falling channel connected to the coupling mechanism. The flue gas conveying pipe passes through the molten salt and the screen and extends into the coupling mechanism to realize the coordinated heat exchange of pyrolysis oil and gas, material conveying and gas-solid flow.

[0012] In the solar-driven pyrolysis product desulfurization and synergistic carbon material cascade sulfur doping system of the present invention, a fluidized air inlet distributor is provided in the fixed bed-fluidized bed coupling mechanism. The fluidized air inlet distributor is located at the top opening of the flue gas conveying pipe. A flow guide umbrella cap is provided at the top of the fixed bed-fluidized bed coupling mechanism. The flow guide umbrella cap is connected to the gas holder through an air passage.

[0013] The fixed-bed-fluidized-bed coupling mechanism is equipped with a fluidized air inlet distributor located at the top opening of the flue gas conveying pipeline. The top opening is equipped with a flow guide cap, which is connected to the gas holder through the gas channel to realize the uniform fluidization reaction of pyrolysis oil and gas and the conveying after gas-solid separation.

[0014] In the solar-driven pyrolysis product desulfurization and cascade sulfur doping system of carbon materials of the present invention, the carbon black collection tank is located below the pyrolysis furnace, a carbon black screening screen is provided between the carbon black collection tank and the pyrolysis furnace, and a discharge valve is provided on one side of the carbon black collection tank.

[0015] The carbon black collection tank is located below the pyrolysis furnace, with a carbon black screening screen between them. A discharge valve is installed on one side of the carbon black collection tank to complete the screening, collection and discharge of pyrolysis carbon black.

[0016] In the solar-driven pyrolysis product desulfurization and carbon material cascade sulfur doping system of the present invention, the molten salt circulation regeneration mechanism includes a separation component, the separation component includes a regeneration tank, the regeneration tank is connected to the second conveying pipeline, a circulation control valve is provided between the regeneration tank and the second conveying pipeline, and a separation baffle is provided inside the regeneration tank.

[0017] In the solar-driven pyrolysis product desulfurization and carbon material cascade sulfur doping system of the present invention, the seawater desalination unit is connected to the regeneration tank through a steam circulation pipeline, and the seawater desalination unit is connected to the carbon black collection tank through a seawater steam delivery pipeline.

[0018] The seawater desalination unit is connected to the regeneration tank via a steam circulation pipeline and to the carbon black collection tank via a seawater steam transmission pipeline, providing a steam heat source for molten salt regeneration and carbon black functional group modification.

[0019] In the solar-driven pyrolysis product desulfurization and cascade sulfur doping system of the present invention, a feeding conveyor belt is provided on one side of the pyrolysis furnace, and the feeding conveyor belt is correspondingly arranged with the tire feed port of the pyrolysis furnace.

[0020] A feeding conveyor belt is installed on one side of the pyrolysis furnace, corresponding to the tire inlet, to achieve continuous and stable feeding of waste tires.

[0021] In the solar-driven pyrolysis product desulfurization and synergistic carbon material cascade sulfur doping system of the present invention, a biochar feed inlet is provided on one side of the fixed bed-fluidized bed coupling mechanism.

[0022] A biochar feed inlet is provided on one side of the fixed-bed-fluidized-bed coupling mechanism for quantitative replenishment of modified biochar, ensuring the continuous desulfurization and sulfur doping reactions.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects: This invention utilizes a pyrolysis furnace combined with a solar thermal concentrator for heating, reducing the reliance on fossil fuels in the waste tire pyrolysis process and decreasing system carbon emissions. Pyrolysis oil and gas are directly transported to a fixed-bed-fluidized-bed coupling mechanism via a flue gas pipeline. Through the synergistic effect of modified biochar and a highly active sulfur-fixing agent, online desulfurization of the pyrolysis oil and gas is achieved, reducing the sulfur content of the pyrolysis products. The fixed-bed-fluidized-bed coupling mechanism, combined with a fixed-bed screening mechanism, converts sulfur pollutants into carbon material modification components, increasing the added value of pyrolysis carbon black. The fixed-bed screening... The combined mechanism and flue gas conveying pipeline heat exchange connection can recover the waste heat of high-temperature flue gas and improve the system energy utilization rate; the purified pyrolysis oil and gas enter the gas holder after the waste heat is recovered by the seawater desalination mechanism, realizing the secondary utilization of waste heat; the seawater desalination mechanism is connected to the carbon black collection tank, providing conditions for the modification of carbon black functional groups and ensuring the desulfurization and sulfur doping effect of modified biochar; the molten salt circulation and regeneration mechanism is connected to the pyrolysis furnace and the fixed bed screening mechanism to realize the circulation and regeneration of molten salt, reduce the generation of secondary solid waste, and enable the system as a whole to achieve clean, efficient and resource-based operation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort: Figure 1 This is a schematic diagram of the overall system of the present invention; Figure 2 This is a schematic diagram of the circulation of molten salt and water vapor in this invention; The components include: 1. Solar concentrator; 2. First conveying pipe; 3. Feed conveyor belt; 4. Waste tires; 5. Tire inlet; 6. Pyrolysis furnace; 7. Flue gas conveying pipe; 8. Second conveying pipe; 9. Carbon black collection tank; 10. Discharge valve; 11. Separation component; 12. Molten salt; 13. Fixed bed screening mechanism; 14. Molten salt inlet; 15. Solid phase falling channel; 16. Modified biochar; 17. Biochar inlet; 18. Fluidized air distributor; 19. Fixed bed-fluidized bed coupling mechanism; 20. Guide umbrella cap; 21. Air duct; 22. Seawater desalination mechanism; 23. Gas holder; 24. Screen; 25. Carbon black screening screen; 26. Circulation control valve; 27. Seawater steam conveying pipe; 28. Separation baffle; 29. ​​Regeneration tank; 30. Water steam circulation pipe. Detailed Implementation

[0025] The technical solutions of the embodiments 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 scope of protection of the present invention.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Reference Figures 1 to 2This invention discloses a solar-driven system for synergistic desulfurization of pyrolysis products and cascade sulfur doping with carbon materials, comprising: a pyrolysis furnace 6, the pyrolysis furnace 6 having an inner cavity and a spiral flow channel, the spiral flow channel being connected to a solar thermal concentrator; a carbon black collection tank 9 being connected to the inner cavity of the pyrolysis furnace 6; and a fixed-bed-fluidized-bed coupling mechanism 19 for fluidized-bed desulfurization and preliminary sulfur doping of pyrolysis oil and gas being connected to the inner cavity of the pyrolysis furnace 6 via a flue gas conveying pipe 7; modified biochar 16 and a highly active sulfur-fixing agent being disposed within the fixed-bed-fluidized-bed coupling mechanism 19; and a system for... A fixed-bed screening and combining mechanism 13 is used to realize the transfer of sulfur from molten salt in a fixed bed and the deep addition of sulfur to biochar. The fixed-bed screening and combining mechanism 13 is heat-exchange connected to the flue gas conveying pipeline 7. A fixed-bed-fluidized-bed coupling mechanism 19 is connected to a gas holder 23. A seawater desalination mechanism 22 is heat-exchange connected between the gas holder 23 and the fixed-bed-fluidized-bed coupling mechanism 19. The seawater desalination mechanism 22 is connected to the carbon black collection tank 9 for functional group modification of carbon black. The seawater desalination mechanism 22 is heat-exchange connected to a molten salt circulation and regeneration mechanism. The molten salt circulation and regeneration mechanism is connected between the pyrolysis furnace 6 and the fixed-bed screening and combining mechanism 13.

[0028] In one alternative embodiment, the solar thermal concentrator includes a solar concentrator 1 for heating a molten salt storage tank. The outlet of the molten salt storage tank is connected to a spiral flow channel via a first conveying pipe 2, and the fixed bed screening mechanism 13 is connected to the spiral flow channel via a second conveying pipe 8.

[0029] In one alternative embodiment, a carbon black screen 25 is provided inside the fixed bed screening mechanism 13, with the carbon black screen 25 located above the molten salt 12. A molten salt inlet 14 is provided on one side of the fixed bed screening mechanism 13, with the molten salt inlet 14 located above the screen 24. A solid phase falling channel 15 is provided at the top of the fixed bed screening mechanism 13, and the solid phase falling channel 15 is connected to the fixed bed-fluidized bed coupling mechanism 19. The flue gas conveying pipe 7 passes sequentially through the molten salt 12, the screen 24, and the top of the fixed bed screening mechanism 13 before extending into the fixed bed-fluidized bed coupling mechanism 19.

[0030] In one alternative embodiment, a fluidized air inlet distributor 18 is provided inside the fixed bed-fluidized bed coupling mechanism 19. The fluidized air inlet distributor 18 is located at the top opening of the flue gas conveying pipe 7. A flow guide cap 20 is provided at the top of the fixed bed-fluidized bed coupling mechanism 19. The flow guide cap 20 is connected to the gas holder 23 through the air passage 21.

[0031] In one alternative embodiment, the carbon black collection tank 9 is located below the pyrolysis furnace 6, and a carbon black screening screen 25 is provided between the carbon black collection tank 9 and the pyrolysis furnace 6. A discharge valve 10 is provided on one side of the carbon black collection tank 9.

[0032] In one alternative embodiment, the molten salt circulation regeneration mechanism includes a separation component 11, which includes a regeneration tank 29 connected to a second conveying pipe 8. A circulation control valve 26 is provided between the regeneration tank 29 and the second conveying pipe 8, and a separation baffle 28 is provided inside the regeneration tank 29.

[0033] In one alternative, the seawater desalination unit 22 is connected to the regeneration tank 29 via a steam circulation pipe 30, and the seawater desalination unit 22 is connected to the carbon black collection tank 9 via a seawater steam delivery pipe 27.

[0034] In one alternative, a feeding conveyor belt 3 is provided on one side of the pyrolysis furnace 6, and the feeding conveyor belt 3 is configured to correspond to the tire feed port 5 of the pyrolysis furnace 6.

[0035] Waste tires 4 are placed on the feeding conveyor belt 3 for automatic feeding.

[0036] In one alternative, a biochar inlet 17 is provided on one side of the fixed-bed-fluidized-bed coupling mechanism 19.

[0037] Workflow: First, the waste tire rubber powder, after being sheared and crushed, is fed into the pyrolysis furnace 6 through the tire inlet 5 using the feeding conveyor belt 3. The pyrolysis furnace 6 is a closed waste tire pyrolysis furnace. The solar concentrator 1 is a dish-type solar concentrator. The solar concentrator 1 heats the molten salt to 1000~1100℃ through concentrated photothermal conversion. The high-temperature molten salt enters the spiral flow channel of the pyrolysis furnace 6 through the closed first conveying pipe 2. The spiral flow channel is a double-jacketed spiral heat exchange pipe, which provides a uniform heat source for the pyrolysis furnace 6, so that the pyrolysis temperature range of 500~1000℃ is stably maintained in the pyrolysis furnace 6. The waste tire 4 completes continuous pyrolysis, producing high-temperature, high-sulfur pyrolysis oil and gas and pyrolysis carbon black at 1000℃. The pyrolysis products remain in a gaseous state throughout the process above 300℃, with no risk of condensation and coking.

[0038] The 1000℃ high-temperature, high-sulfur pyrolysis oil and gas generated by the pyrolysis furnace 6 is directly sent to the fixed-bed molten salt heat storage and sulfur transfer zone of the fixed-bed-fluidized-bed coupling mechanism 19 through the flue gas conveying pipe 7. The flue gas conveying pipe 7 is a closed and insulated pipe. The top of the flue gas conveying pipe 7 is connected to the heat exchange tank inside the fixed-bed screening and combination mechanism 13. The high-temperature, high-sulfur pyrolysis oil and gas and the solid molten salt exchange heat efficiently. The molten salt absorbs a large amount of latent heat through solid-liquid phase change, and completes the efficient storage of waste heat from the high-temperature flue gas. At the same time, the temperature of the pyrolysis oil and gas is precisely reduced to 500~600℃ after heat exchange, providing the optimal temperature conditions for the subsequent fluidized-bed desulfurization reaction.

[0039] The pyrolysis oil and gas, cooled to 500-600℃ by heat exchange, are uniformly introduced into the fixed-bed-fluidized-bed coupling mechanism 19 through the fluidized air inlet distributor 18. Within the fixed-bed-fluidized-bed coupling mechanism 19, modified biochar 16, enriched with sulfur-fixing active functional groups such as hydroxyl and carboxyl groups, works synergistically with highly active metal sulfur-fixing agents such as calcium-based and magnesium-based agents to efficiently capture and remove gaseous sulfides from the pyrolysis oil and gas, achieving deep desulfurization of the pyrolysis oil and gas. Simultaneously, during the desulfurization process, the modified biochar 16 captures gaseous sulfides, forming solid organic sulfur on its surface, thus completing the sulfur doping of the biochar.

[0040] After desulfurization and purification, the pyrolysis oil and gas flow out from the top of the fluidized bed. After the solid dust entrained by the flow guide cap 20 is removed, it enters the subsequent waste heat utilization unit through the three-way reversing valve. The flow guide cap 20 is a gas-solid separation flow guide cap. The modified biochar 16 and the sulfur-fixing agent loaded with sulfides that have completed the sulfur fixation reaction directly enter the lower fixed bed molten salt heat storage and sulfur transfer zone through the solid phase falling channel.

[0041] After the modified biochar 16 and the sulfur-fixing agent are fed into the fixed bed screening and combining mechanism 13, they are thoroughly mixed with the molten salt formed by high-temperature oil and gas heat exchange. The system uses a binary mixed molten salt of NaCl-CaCl2 with a mass ratio of 6:4 and a melting point between 500℃ and 510℃. The sulfur-fixing agent is a CaO-based high-activity sulfur-fixing agent.

[0042] The CaO-based sulfur-fixing agent that completes sulfur fixation generates CaS. After being fully contacted with the molten mixed salt, the decomposition temperature of CaS drops from above 1200℃ to below 580℃ under the eutectic effect, which is perfectly matched with the reaction temperature of 550~650℃ in the fixed bed. The sulfur-fixing agent and molten salt are mixed at a mass ratio of 1:10~1:15 and eutectic is rapidly completed in the molten environment, which accelerates the directional decomposition of CaS and releases highly active sulfur atoms, providing a sulfur source for deep sulfur doping of biochar. Preliminary chemical sulfur doping in fluidized bed: Under the fluidized bed reaction environment of 500~600℃, the hydroxyl and carboxyl active functional groups enriched on the surface of modified biochar 16 undergo in-situ chemical bonding with gaseous sulfides in pyrolysis oil and gas, forming shallow stable CS bonds on the surface of the carbon material, thus completing the first stage of in-situ chemical sulfur doping.

[0043] Fixed-bed deep bulk sulfur doping: In the molten salt reaction environment of 550~650℃, the highly active sulfur atoms released by the decomposition of the sulfur fixation agent diffuse into the carbon skeleton of biochar and form deep bonds with the carbon matrix to form stable bulk CS and CSC bonds, completing the second-stage deep controllable sulfur doping and realizing the directional resource transformation of sulfur pollutants in pyrolysis oil and gas into functional dopants for carbon materials.

[0044] Thus, the entire process achieves deep removal of gaseous sulfur pollutants from the pyrolysis gas, and cascade sulfur doping with carbon materials, realizing the synergistic process of "desulfurization and purification - sulfur resource utilization - high-value modification of carbon materials". Finally, the cascaded sulfur-doped biochar and molten salt achieve precise solid-liquid separation through sieve 24, which is a gradient pore size sieve. The modified biochar 16 on sieve 24 is collected as a high-value-added sulfur-doped carbon product; the molten salt below sieve 24 enters the molten salt circulating heat storage unit.

[0045] The high-temperature molten salt generated by solar concentrator 1 provides the main heat source for pyrolysis furnace 6. The waste heat from the high-temperature, high-sulfur pyrolysis oil and gas is first used to melt the molten salt in the fixed bed and provide heat for the sulfur transfer reaction, achieving primary waste heat recovery. The desulfurized pyrolysis oil and gas after heat exchange and cooling then provides a heat source for the seawater desalination unit 22, achieving secondary waste heat recovery. The molten salt that still retains heat after sulfur transfer provides insulation and supplementary heating to the pyrolysis furnace through independent pipelines when sunlight is insufficient, achieving stable utilization of solar energy across time periods. The high-temperature heating molten salt and the supplementary heating molten salt circulate through independent pipelines to avoid cross-loss of heat, achieving a full-dimensional energy closed loop of solar energy, flue gas waste heat, and molten salt heat storage, significantly improving the overall energy utilization efficiency of the system.

[0046] After the molten salt completes its heat preservation and replenishment in pyrolysis furnace 6 at night, circulation is stopped and it is discharged into separation component 11. It is then allowed to cool naturally to room temperature and completely solidify, with sulfur-fixing byproducts and carbon powder adhering only to the surface of the molten salt crystals. The pre-separated molten salt crystals are sent to the water-soluble chamber and mixed with fresh water produced by seawater desalination unit 22 at a liquid-to-solid ratio of 2:1 at room temperature. After the molten salt is completely dissolved, it is filtered. The filter residue consists of sulfur-fixing byproducts and carbon powder, while the filtrate is a high-purity molten salt aqueous solution. The filtered molten salt aqueous solution is sent to the recrystallization chamber. The next day, after solar concentrator 1 is started, a portion of the residual heat (150~200℃) from the low-temperature section of the molten salt is used to pass through the molten salt conveying pipeline, and circulation control valve 26 is opened to evaporate the aqueous solution at low temperature, causing the molten salt to recrystallize and precipitate. The evaporated water vapor is condensed and recovered to the fresh water tank for the next water-soluble separation, forming a water-molten salt closed-loop cycle. The molten salt after recrystallization has high purity and is recycled back into the fixed bed for reuse; the filter residue is activated and the desulfurizing agent is returned to the fluidized bed for reuse, with no secondary solid waste throughout the process.

[0047] This invention utilizes a pyrolysis furnace 6 in conjunction with a solar thermal concentrator to reduce the reliance on fossil fuels in the pyrolysis of waste tires 4, thereby reducing system carbon emissions. Pyrolysis oil and gas are directly fed into a fixed-bed-fluidized-bed coupling mechanism 19 via a flue gas conveying pipe 7. Under the synergistic effect of modified biochar 16 and a highly active sulfur-fixing agent, online desulfurization of the pyrolysis oil and gas is achieved, reducing the sulfur content of the pyrolysis products. Furthermore, the fixed-bed-fluidized-bed coupling mechanism 19, in conjunction with a fixed-bed screening and combining mechanism 13, converts sulfur pollutants into carbon material modification components, increasing the added value of pyrolysis carbon black. The fixed-bed screening and combining mechanism 13... 3 is connected to the flue gas conveying pipeline 7 for heat exchange, recovering the waste heat of high-temperature flue gas and improving the energy utilization rate of the system; the purified pyrolysis oil and gas enter the gas holder 23 after recovering waste heat through the seawater desalination mechanism 22, realizing the secondary utilization of waste heat; the seawater desalination mechanism 22 is connected to the carbon black collection tank 9, providing conditions for the modification of carbon black functional groups and ensuring the desulfurization and sulfur doping effect of modified biochar 16; the molten salt circulation and regeneration mechanism is connected to the pyrolysis furnace 6 and the fixed bed screening and combining mechanism 13 to realize the circulation and regeneration of molten salt, reduce the generation of secondary solid waste, and enable the system as a whole to achieve clean, efficient and resource-based operation. The solar concentrator 1, together with the first conveying pipe 2 and the second conveying pipe 8, forms an independent molten salt circulation loop, ensuring stable heating and preventing cross-loss of heat, thus improving the system's energy supply stability and efficiency. The fixed-bed screening mechanism 13 includes a carbon black screening screen 25, a screen 24, a molten salt inlet 14, and a solid phase falling channel 15, achieving precise material separation and continuous conveying, ensuring stable connection between desulfurization and sulfur blending processes. The fixed-bed-fluidized-bed coupling mechanism 19 includes a fluidized air inlet distributor 18 and a guide umbrella cap 20, ensuring uniform distribution of pyrolysis oil and gas and completing gas-solid separation, improving desulfurization efficiency and preventing dust entrainment. The carbon black collection tank 9, in conjunction with the carbon black screening screen 25 and the discharge valve 10, realizes the screening, collection, and discharging of pyrolysis carbon black. Quantitative discharge ensures a stable supply of modified biochar; the molten salt circulation and regeneration mechanism, with its regeneration tank 29, circulation control valve 26, and separation baffle 28, enables offline regeneration and purification of molten salt, solving the problems of difficult desulfurizer regeneration and the generation of secondary solid waste; the seawater desalination mechanism 22, through the water vapor circulation pipeline 30 and the seawater vapor transmission pipeline 27, simultaneously provides a heat source for molten salt regeneration and carbon black modification, improving the comprehensive utilization level of waste heat in the system; the feeding conveyor belt 3, in conjunction with the tire feed inlet 5, enables continuous and stable feeding of waste tires 4, ensuring continuous operation of the pyrolysis process; the biochar feed inlet 17 can replenish modified biochar 16 as needed, maintaining the continuous and stable operation of fluidized bed desulfurization and sulfur doping reactions, ensuring long-term reliable operation of the system.

[0048] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0049] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A solar-driven system for synergistic desulfurization of pyrolysis products and cascade sulfur doping of carbon materials, characterized in that, include: The pyrolysis furnace (6) is equipped with an inner cavity and a spiral flow channel. The spiral flow channel is connected to a solar thermal concentrator. The inner cavity of the pyrolysis furnace (6) is connected to a carbon black collection tank (9). The inner cavity of the pyrolysis furnace (6) is connected to a fixed bed-fluidized bed coupling mechanism (19) for fluidized bed desulfurization and preliminary sulfur doping of pyrolysis oil and gas through a flue gas conveying pipe (7). Modified biochar (16) and a highly active sulfur-fixing agent are provided in the fixed bed-fluidized bed coupling mechanism (19). The fixed bed-fluidized bed coupling mechanism (19) is connected to a fixed bed screening mechanism below it for realizing fixed bed molten salt sulfur transfer and deep sulfur doping of biochar. The fixed bed screening and combining mechanism (13) is heat-exchange connected to the flue gas conveying pipeline (7), the fixed bed-fluidized bed coupling mechanism (19) is connected to the gas holder (23), the gas holder (23) and the fixed bed-fluidized bed coupling mechanism (19) are heat-exchange connected to the seawater desalination mechanism (22), the seawater desalination mechanism (22) is connected to the carbon black collection tank (9) for functional group modification of carbon black, the seawater desalination mechanism (22) is heat-exchange connected to the molten salt circulation and regeneration mechanism, the molten salt circulation and regeneration mechanism is connected between the pyrolysis furnace (6) and the fixed bed screening and combining mechanism (13).

2. The system for solar-driven pyrolysis product desulfurization and cascade sulfur doping of carbon materials according to claim 1, characterized in that: The solar thermal concentrator includes a solar concentrator (1) for heating a molten salt storage tank. The molten salt storage tank is connected to a spiral flow channel via a first conveying pipe (2). The fixed bed screening and combining mechanism (13) is connected to the spiral flow channel via a second conveying pipe (8).

3. The system for solar-driven pyrolysis product desulfurization and cascade sulfur doping of carbon materials according to claim 1, characterized in that: A carbon black screen (25) is provided inside the fixed bed screening and combining mechanism (13). The carbon black screen (25) is located above the molten salt (12). A molten salt inlet (14) is provided on one side of the fixed bed screening and combining mechanism (13). The molten salt inlet (14) is located above the screen (24). A solid phase falling channel (15) is opened at the top of the fixed bed screening and combining mechanism (13). The solid phase falling channel (15) is connected to the fixed bed-fluidized bed coupling mechanism (19). The flue gas conveying pipe (7) passes through the molten salt (12), the screen (24) and the top of the fixed bed screening and combining mechanism (13) in sequence and then extends into the fixed bed-fluidized bed coupling mechanism (19).

4. The system for solar-driven pyrolysis product desulfurization and cascade sulfur doping of carbon materials according to claim 1, characterized in that: The fixed-bed-fluidized-bed coupling mechanism (19) is provided with a fluidized air inlet distributor (18), which is located at the top opening of the flue gas conveying pipe (7). The top of the fixed-bed-fluidized-bed coupling mechanism (19) is provided with a flow guide cap (20), which is connected to the gas holder (23) through the air passage (21).

5. The system for solar-driven pyrolysis product desulfurization and cascade sulfur doping of carbon materials according to claim 1, characterized in that: The carbon black collection tank (9) is located below the pyrolysis furnace (6), and a carbon black screening screen (25) is provided between the carbon black collection tank (9) and the pyrolysis furnace (6). A discharge valve (10) is provided on one side of the carbon black collection tank (9).

6. The system for solar-driven pyrolysis product desulfurization and cascade sulfur doping of carbon materials according to claim 1, characterized in that: The molten salt circulation regeneration mechanism includes a separation component (11), the separation component (11) includes a regeneration tank (29), the regeneration tank (29) is connected to the second conveying pipe (8), a circulation control valve (26) is provided between the regeneration tank (29) and the second conveying pipe (8), and a separation baffle (28) is provided inside the regeneration tank (29).

7. The system for solar-driven pyrolysis product desulfurization and cascade sulfur doping of carbon materials according to claim 1, characterized in that: The seawater desalination unit (22) is connected to the regeneration tank (29) through a water vapor circulation pipe (30), and the seawater desalination unit (22) is connected to the carbon black collection tank (9) through a seawater steam transmission pipe (27).

8. A solar-driven system for synergistic desulfurization of pyrolysis products and cascade sulfur doping of carbon materials according to claim 1, characterized in that: A feeding conveyor belt (3) is provided on one side of the pyrolysis furnace (6), and the feeding conveyor belt (3) is provided in correspondence with the tire feed port (5) of the pyrolysis furnace (6).

9. A solar-driven system for synergistic desulfurization of pyrolysis products and cascade sulfur doping of carbon materials according to claim 1, characterized in that: A biochar inlet (17) is provided on one side of the fixed bed-fluidized bed coupling mechanism (19).

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