Coupling solar energy to accelerate hydrogen production process and device for pyrolysis of waste tires

Abstract

The application specifically relates to a coupling solar energy accelerating waste tire pyrolysis hydrogen production process and device, which prepares molten salt and waste tire particles first, then adds the reactor into the molten salt and calcium oxide, and generates gaseous substances and ash through waste tire particle cracking reaction under a protective atmosphere, then purifies the gaseous substances, obtains hydrogen and other gases through the action of a catalyst, classifies and stores the hydrogen and other gases, and finally recycles the molten salt. The device is used for waste tire pyrolysis, realizes efficient pyrolysis through self-suction type stirrers and molten salt circulation. The inner curved baffle of the reaction kettle optimizes heat transfer, and a demister separates gas and liquid. Pyrolysis gas is separated into hydrogen and CO for storage after purification, condensation and catalytic reforming, a molten salt loop is provided with a carbon black filter and double energy heating. The application utilizes solar energy to heat molten salt, reduces cost and is environmentally friendly, improves pyrolysis efficiency and reduces pollution. The pyrolysis reactor is provided with a self-suction type stirrer and a hemispherical protrusion on the inner wall of the baffle, which improves mixing effect and heat transfer efficiency.

Description

Technical Field

[0001] This application belongs to the field of resource recycling technology, specifically relating to a process and apparatus for accelerating hydrogen production from waste tires by coupling solar energy. Background Technology

[0002] Due to their heat resistance, mechanical resistance, and resistance to biodegradation, waste tires, when accumulated over a long period, release toxic substances (such as polycyclic aromatic hydrocarbons and heavy metals), polluting soil and water sources, and even posing a fire hazard, thus being known as "black pollution." How to efficiently and cleanly utilize waste tires has become a key issue for the circular economy and low-carbon development.

[0003] Currently, pyrolysis is the mainstream technology for treating waste tires. It decomposes tire components at high temperatures (400-800℃) under anaerobic conditions, producing pyrolysis oil (40-55%), carbon black (30-35%), steel wire (10-15%), and combustible gases (including H2, CH4, CO, etc.). Compared with traditional incineration and landfill, pyrolysis has advantages such as high resource utilization (>95%) and less secondary pollution, but it still faces the following technical bottlenecks:

[0004] Energy consumption and carbon emissions: Existing pyrolysis processes mostly rely on fossil fuels (such as natural gas and coal) or electric heating to maintain high-temperature reactions, resulting in high energy costs and high carbon emission intensity (approximately 0.8-1.2 tons of CO2 are emitted per ton of tires processed). For example, Chinese patent CN114904894B discloses a method and apparatus for treating organic solid waste based on molten salt, which still uses fossil raw materials as the heat source. Uneven heat transfer and reaction efficiency limitations: Waste tires have low thermal conductivity (0.1-0.3 W / m·K), and traditional static or mechanically stirred reactors suffer from low heat and mass transfer efficiency, local overheating and coking, resulting in slow pyrolysis reaction rates and poor product selectivity (low proportion of light components in cracked oil and hydrogen yield of less than 5%). Insufficient product quality and hydrogen yield: The hydrogen component in conventional pyrolysis combustible gas is generally less than 20%, and tar is generated (affecting subsequent utilization).

[0005] Therefore, many scholars have tried to study a new process to overcome the technical bottleneck. CN117604237A discloses a solar-driven circuit board pyrolysis hydrogen production and metal recovery co-production process. It is based on solar heating to crack the circuit board and recover hydrogen. During the day, solar energy can be used to heat molten salt, but when there is no sun, it still needs to rely on fossil fuels.

[0006] Therefore, in view of the problems of high energy consumption, insufficient hydrogen production rate and uneven heat transfer in the existing waste tire pyrolysis process, there is an urgent need to propose a process and device for hydrogen production by coupled solar energy to accelerate the pyrolysis of waste tires, so as to solve the problems existing in the existing technology. Summary of the Invention

[0007] To address the problems of high energy consumption, insufficient hydrogen yield, and uneven heat transfer in existing waste tire pyrolysis processes, this application proposes a solar-coupled accelerated waste tire pyrolysis hydrogen production process and apparatus to solve the problems existing in the prior art.

[0008] The technical solution of this application is as follows:

[0009] On the one hand, this application provides a process for accelerating hydrogen production from waste tire pyrolysis using solar energy, comprising the following steps:

[0010] Step S1. Preparation of molten salt and waste tire pellets

[0011] The three substances Li2CO3, K2CO3 and Na2CO3 were mixed evenly, heated and then kept at the temperature and cooled to room temperature. Finally, the mixture was crushed and sieved to obtain a ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3.

[0012] The steel wires are stripped from the waste tires and crushed to obtain waste tire pellets.

[0013] The preparation of molten salt and waste tire pellets described above are done in no particular order;

[0014] Step S2. Pyrolysis of waste tires

[0015] A ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3, calcium oxide, and waste tire particles are added to a reactor. Under a protective atmosphere, the waste tire particles undergo a pyrolysis reaction to produce gaseous substances and ash. The gaseous substances are H2, small molecule aliphatic hydrocarbons, aromatic hydrocarbons, CO, and CO2. The ash includes elemental metals and inorganic non-metallic components.

[0016] Step S3. Catalytic reforming

[0017] The gaseous substance in step S2 is purified by passing it through an alkaline liquid, then condensed to remove impurities, and finally catalytically reformed under the action of a composite metal oxide nickel-magnesium-aluminum catalyst to obtain hydrogen and other gases for separate storage.

[0018] Step S4. Recycling of molten salt and calcium oxide

[0019] The ash in step S2 is absorbed by the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 and calcium oxide to obtain a mixture. The mixture is then decarbonized and returned to the molten salt storage tank.

[0020] Preferably, the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 in step S1 includes 20-50 wt% Li2CO3, 20-50 wt% Na2CO3, and 20-50 wt% K2CO3.

[0021] More preferably, the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 in step S1 includes 32.1% Li2CO3, 33.4% Na2CO3, and 34.5% K2CO3 (wt%).

[0022] Preferably, in step S1, the three substances Li2CO3, K2CO3, and Na2CO3 are heated to 600℃ at a heating rate of 10℃ / min, held at that temperature for 6 hours, and then passed through a 60-mesh sieve; the waste tire particles are rubber tires.

[0023] Preferably, in step S2, the amount of calcium oxide added is 8-10% of the mass of the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3; the amount of waste tire particles added is 20% of the mass of the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3; the protective gas is nitrogen, and the introduction rate is 25 ml / min; the pyrolysis reaction is heated in a gradient, with a heating rate of 20℃ / min, first heated to 700℃, held for 0.5 h, and then heated to 750-800℃, held for 5-10 min.

[0024] Preferably, the small molecule aliphatic hydrocarbons include methane, ethane, ethylene, propane, and propylene; the aromatic hydrocarbons include benzene, toluene, and xylene.

[0025] Preferably, the alkaline liquid in step S3 is a 5 mol / L sodium hydroxide solution, the condensation temperature is 6°C, the gas flow rate of the gaseous substance is 25 ml / min, and the n(Ni) in the composite metal oxide nickel-magnesium-aluminum catalyst is... 2+ ):n(Mg 2+ ):n(Al 3+ = 0.5:1.2:1.

[0026] On the other hand, this application provides an apparatus for coupling solar energy to accelerate the pyrolysis of waste tires to produce hydrogen, including a pyrolysis reactor. The pyrolysis reactor has a solid waste inlet, a gas inlet, and a gas outlet at its top. A molten salt inlet is located below the side wall of the pyrolysis reactor, and a molten salt outlet is also located below the side wall. The solid waste inlet is connected to a tire shredder, and the molten salt inlet is connected to the inlet of a molten salt storage tank. The molten salt storage tank also has an outlet. A molten salt outlet pipeline is connected to the molten salt outlet. A carbon black filter is installed on the pipeline, and the carbon black filter has a filter outlet and a filter inlet. The carbon black filter inlet is connected to the molten salt outlet, and the carbon black filter outlet is connected to two parallel pipelines. Each of the two parallel pipelines has a valve. One pipeline is connected to an electric heating device, and the other pipeline is connected to a trough-type concentrating solar collector. Both parallel pipelines are connected to the molten salt inlet.

[0027] Preferably, the electric heating device is further connected in series with a photovoltaic panel and a storage battery. The photovoltaic panel is used to convert solar energy into electrical energy and store it in the storage battery. The storage battery heats the molten salt at night or on cloudy days via the electric heating device. The gas outlet on the pyrolysis reactor is connected in sequence to a gas processing device, a condenser, a catalytic reforming reactor, and a gas separator along the gas flow direction. The gas separator is also connected to a hydrogen storage tank and a CO storage tank. A gas detection system for detecting gas composition is provided on the pipeline connecting the catalytic reforming reactor and the gas separator. A heating layer is provided outside the catalytic reforming reactor.

[0028] Preferably, the pyrolysis reactor includes a motor located at the top and a self-priming agitator located inside the pyrolysis reactor. The motor is connected to the self-priming agitator via a coupling. The self-priming agitator includes a hollow drive shaft, a self-priming impeller located near the motor, and an axial flow impeller located away from the motor. A sleeve is welded to the blades of the axial flow impeller, the radius of which is smaller than the radius of the impeller blade, and the sleeve extends to the bottom of the pyrolysis reactor.

[0029] Preferably, the pyrolysis reactor has a reaction vessel inside, a heating layer outside the reaction vessel, and a curved baffle inside the reaction vessel along the axial direction. The surface of the curved baffle is uniformly provided with hemispherical protrusions to increase the heat transfer area and increase the pyrolysis rate of waste tires. A demister is also provided above the reaction vessel to remove foam from the oil and gas. A thermocouple and a pressure gauge are also provided above the pyrolysis reactor to detect the internal temperature of the reaction vessel.

[0030] The beneficial effects of this application are as follows:

[0031] Molten salts have broad application prospects in the energy and industrial fields due to their advantages such as high energy density, wide liquid temperature range, low vapor pressure, good heat transfer performance, long life, high safety, and environmental friendliness. This invention utilizes the excellent heat transfer characteristics of molten salts to transfer solar energy into the molten salt through both light-heat and light-electricity-heat pathways. This allows the high-temperature liquid molten salt to serve as the heat source for the pyrolysis of waste tire particles. The liquid molten salt, combined with the self-priming agitator of this invention, enables the waste tire particles to quickly and uniformly fuse with the molten salt, greatly accelerating the reaction speed and improving product quality. Simultaneously, the alkaline molten salt neutralizes the acidic atmosphere generated during the reaction, reducing corrosion to the equipment.

[0032] Compared with traditional pyrolysis technology, the technical solution of the present invention has the following advantages:

[0033] This invention utilizes solar energy to heat molten salt. Solar energy is a renewable and pollution-free energy source. By using solar energy to drive the pyrolysis of waste tires to produce hydrogen, there is no need to consume traditional fossil fuels or large amounts of electricity, thus significantly reducing energy costs and meeting the requirements of sustainable development.

[0034] This invention uses molten salt as an intermediate heat transfer medium to heat waste tires. Molten salt has excellent thermal conductivity, which can quickly and evenly transfer heat to waste tires, significantly improving pyrolysis efficiency. Furthermore, as a liquid medium, molten salt can fully contact waste tires, avoiding the uneven heat transfer problem commonly found in traditional pyrolysis. Molten salt can also suppress the release of harmful gases during pyrolysis, while retaining harmful metal elements within the molten salt, reducing environmental pollution.

[0035] This invention adds a self-priming stirrer to the traditional pyrolysis reactor, which enables more uniform mixing of liquid molten salt and waste tire particles, significantly improving the reaction rate and product quality.

[0036] This invention adds numerous hemispherical protrusions to the inner wall of the baffle outside the self-priming stirrer in the pyrolysis reactor. The presence of these protrusions increases the actual heat transfer area and improves heat transfer efficiency. The protrusion structure can work in synergy with the stirrer to further enhance the mixing effect of molten salt and tire debris. By changing the flow direction and speed of the fluid, the protrusions can make the material more evenly dispersed in the reactor.

[0037] This application incorporates calcium oxide (CaO) into the molten salt. CaO reacts with sulfur-containing compounds released during the pyrolysis of waste tires to form stable sulfides, reducing the sulfur content in the exhaust gas. CaO also reacts with CO2 generated during the pyrolysis of waste tires to form CaCO3, which can be regenerated back to CaO through high-temperature calcination, enabling recycling. CaO neutralizes acidic gases in the pyrolysis gas, preventing corrosion of the reactor and pipelines. CaO regulates the acid-base balance of the molten salt, preventing performance degradation due to the accumulation of acidic gases, enhancing the adsorption capacity of the molten salt for heavy metals, and reducing the risk of heavy metal leaching from the ash. By absorbing CO2 and sulfides, CaO reduces the generation of tar and impurity gases, improves hydrogen selectivity in the catalytic reforming stage, and simultaneously inhibits carbon deposition, extending catalyst life. Attached Figure Description

[0038] Figure 1 This application presents a process flow diagram for accelerating hydrogen production from waste tire pyrolysis using solar energy.

[0039] Figure 2 This is a diagram of a device for accelerating hydrogen production from waste tire pyrolysis using solar energy coupled with the present application.

[0040] Figure 3 This is a schematic diagram of a pyrolysis reactor for a solar-coupled accelerated waste tire pyrolysis hydrogen production device according to this application;

[0041] Figure 4 This is a schematic diagram of the interior of the pyrolysis reactor of a solar-coupled accelerated waste tire pyrolysis hydrogen production device according to this application;

[0042] Figure 5 This is a schematic diagram of a self-priming agitator for a solar-coupled accelerated waste tire pyrolysis hydrogen production device according to this application;

[0043] Figure 6 This is a schematic diagram of a curved baffle for a solar-coupled accelerated hydrogen production device from waste tire pyrolysis.

[0044] Explanation of symbols in the attached diagram: 1. Tire shredder; 2. Pyrolysis reactor; 3. Electric heating device; 4. Storage battery; 5. Photovoltaic panel; 6. Parabolic trough concentrator; 7. Valve; 8. Molten salt storage tank; 9. Carbon black filter; 10. Nitrogen cylinder; 11. Gas processing device; 12. Condenser; 13. Catalytic reforming reactor; 14. Gas detection system; 15. Gas separator; 16. Hydrogen storage tank; 17. CO storage tank;

[0045] 201. Gas outlet; 202. Molten salt inlet; 203. Molten salt outlet; 204. Motor; 205. Gas inlet; 206. Solid waste inlet; 207. Demister; 208. Reactor; 209. Curved baffle; 210. Self-priming stirrer; 211. Hollow drive shaft; 212. Pressure gauge; 213. Thermocouple; 214. Heating layer;

[0046] 2101. Coupling; 2102. Self-priming impeller; 2103. Axial flow propeller; 2104. Sleeve. Detailed Implementation

[0047] To further illustrate the technical means and effects adopted by this application in order to achieve the intended purpose of the invention, the following detailed description of the specific implementation methods, structures, features and effects of this application, in conjunction with preferred embodiments, is provided below.

[0048] Currently, the main methods for disposing of waste tires are landfill and incineration, which present the following problems:

[0049] Low resource utilization: Landfilling and incineration methods cannot effectively recover useful components from waste tires, resulting in resource waste. Severe environmental pollution: Landfilling occupies a large amount of land resources and may cause soil and groundwater pollution; incineration produces large amounts of waste gas and residue, polluting the environment. High processing costs: Both landfilling and incineration require significant land resources or fuel consumption, resulting in high processing costs. Existing technologies mostly use molten salt as a catalytic cracking material, but the cracking products are mostly pyrolysis oil, and the molten salt cracking of waste tires is incomplete, not a clean energy source, and cannot be directly utilized. The applicant first attempts to utilize solar energy as a clean heat source. During the day, molten salt is heated using a parabolic trough concentrator, and at night, it is heated using an electric heating device. The electricity in the electric heating device is generated by converting solar energy into electrical energy through photovoltaic panels. Secondly, the applicant initially used a KCl:NaCl = 1:1 mixture, but the pyrolysis effect was not ideal. This may be because the molten chloride salt has poor thermal conductivity and cannot quickly transfer heat to the tires, resulting in low pyrolysis efficiency of waste tires. Therefore, the applicant used a ternary mixed acid of Li2CO3-Na2CO3-K2CO3 as the molten salt and found that the pyrolysis performance was improved. However, more sulfides were produced during pyrolysis. After extensive research, the applicant tried to introduce calcium oxide into the pyrolysis and found that it had a better absorption effect on sulfides.

[0050] Device Examples

[0051] This embodiment provides a device for accelerating hydrogen production from waste tire pyrolysis using solar energy, as shown in the attached diagram. Figures 2-6 As shown, the details are as follows:

[0052] The pyrolysis reactor 2 includes a motor 204 mounted at the top and a self-priming agitator 210 mounted inside the reactor. The motor 204 is connected to the self-priming agitator 210 via a coupling 2101. The self-priming agitator 210 includes a hollow drive shaft 211, a self-priming impeller 2102 mounted on the hollow drive shaft 211 near the motor 204, and an axial flow impeller 2103 mounted away from the motor 204. A sleeve 2104 is welded to the blades of the axial flow impeller 2103, the radius of which is smaller than the radius of the blades. The sleeve 2104 extends to the bottom of the pyrolysis reactor 2. A reaction vessel 208 is located inside the pyrolysis reactor 2. A heating layer 214 is located outside the reaction vessel 208. A curved baffle 209 is fixed inside the reaction vessel 208 along its axial direction. Hemispherical protrusions are evenly distributed on the surface of the baffle. A demister 207 is installed above the reaction vessel 208. The pyrolysis reactor 2 is equipped with a solid waste inlet 206, a gas inlet 205, and a gas outlet 201 at its top. A molten salt inlet 202 and a molten salt outlet 203 are located at the bottom of the side wall of the pyrolysis reactor 2. The solid waste inlet 206 is connected to the tire shredder 1 via a pipe. The pyrolysis reactor 2 is also equipped with a pressure gauge 212 and a thermocouple 213 for monitoring the pressure and temperature inside the reactor 208.

[0053] The molten salt storage tank 8 is located near the pyrolysis reactor 2 and has an inlet and an outlet. The outlet of the molten salt storage tank 8 is connected to the molten salt inlet 202 of the pyrolysis reactor 2 via a pipe. The molten salt outlet 203 of the pyrolysis reactor 2 is connected to the inlet of the molten salt storage tank 8. A carbon black filter 9 is installed on the pipe connecting the molten salt outlet 203 and the inlet of the molten salt storage tank 8. The filter has a filter outlet and a filter inlet. The filter outlet is connected to two parallel pipes, each equipped with a valve 7. One pipe is connected to an electric heating device 3, and the other pipe is connected to a solar thermal collector. Both parallel pipes are ultimately connected to the molten salt inlet 202. The electric heating device 3 is also connected in series with a photovoltaic panel 5 and a battery 4. The photovoltaic panel 5 is used to convert solar energy into electrical energy stored in the battery 4. The battery heats the molten salt at night or on cloudy days via the electric heating device 3 to ensure the heating needs of the molten salt.

[0054] The gas outlet 201 on the pyrolysis reactor 2 is connected in sequence to the gas processing device 11, the condenser 12, the catalytic reforming reactor 13, the gas detection system 14, and the gas separator 15 via pipelines. The gas separator 15 is connected to the hydrogen storage tank 16 and the CO storage tank respectively. The gas detection system 14 for detecting gas composition is provided on the pipeline connecting the catalytic reforming reactor 13 and the gas separator 15. The catalytic reforming reactor 13 is provided with a heating layer 214 on its exterior.

[0055] Implementation principle of the device:

[0056] At the start of the experiment, nitrogen cylinder 10 is opened, and nitrogen gas is purged through the outlet of nitrogen cylinder 10 via a flow meter to purge the entire reaction system, ensuring the entire reaction system is under a nitrogen atmosphere to prevent oxygen in the air from affecting the reaction. Then, carbon dioxide cylinder is opened, and carbon dioxide and nitrogen enter the pyrolysis reactor 2 together as a protective gas for the pyrolysis reaction. During the day, valve 7 on the pipeline connecting to the trough-type concentrator 6 is opened. At this time, the system relies on the trough-type concentrator 6 to absorb solar energy and convert it into heat, which is then transferred to the molten salt and calcium oxide in the pipeline. The liquid molten salt and calcium oxide flow into the molten salt storage tank 8. The molten salt enters the reactor 208 of the pyrolysis reactor 2 through the molten salt inlet 202. Simultaneously, waste tires pass through a tire shredder and then enter the reactor 208 of the pyrolysis reactor 2 through the solid waste inlet 206. Calcium oxide also enters the reactor 208 of the pyrolysis reactor 2 through the solid waste inlet 206.

[0057] When the motor 204 is powered on, it drives the hollow drive shaft 211 to rotate. The hollow drive shaft 211 then drives the self-priming stirrer 210 to work. The self-priming stirrer 210 can generate a strong stirring force, which quickly mixes the molten salt with the solid particles, allowing the reactants to come into full contact and creating favorable conditions for the pyrolysis reaction. This helps to improve the conversion rate and product uniformity. In addition, the self-priming stirrer can make the materials in the reactor form a good heat exchange, allowing the heat to be distributed more evenly in the materials. The protrusions on the curved baffle 209 added inside the reactor 208 will change the fluid flow state on the surface of the curved baffle 209, forming small eddies and turbulence around the protrusions. These eddies and turbulence effectively disrupt the boundary layer formed by the fluid on the baffle surface, reducing thermal resistance and enhancing heat transfer. After the molten salt enters the pyrolysis reactor 2, the heating layer 214 outside the reactor continuously provides heat to the molten salt in the reactor 208 via electric heating. During the pyrolysis of waste tires, a large amount of oil-gas mixture is generated. This mixture may contain a lot of foam. After the foamy gas flows through the demister 207, the gas changes its flow direction due to the complex structure, while the droplets in the foam continue to move in the original direction due to inertia, thus colliding with the demister. After the collision, the droplets aggregate and grow larger, separating from the gas under gravity and flowing down the demister wall. The temperature and pressure inside the reactor 208 are controlled by the thermocouple 213 and pressure device on the pyrolysis reactor 2. The gas generated by pyrolysis is discharged through the gas outlet 201 at the top of the pyrolysis reactor 2, and the molten salt after the reaction leaves the pyrolysis reactor 2 through the molten salt outlet 203 in the upper part.

[0058] The gas discharged from the gas outlet 201 at the top of the pyrolysis reactor 2 is treated by the gas treatment device 11 to absorb alkaline liquid. Then, it passes through the condenser 12 to remove moisture and alkaline liquid mixed in with other gases. The purified gas enters the catalytic reforming reactor 13, where small molecule aliphatic hydrocarbons and aromatic hydrocarbons are further catalytically cracked under the action of a catalyst, improving the hydrogen production and recovery rate. The gas exiting the catalytic reforming reactor 13 is initially detected by the gas detection system 14 to detect the content of each component. Then, it passes through the gas separator 15 to separate hydrogen from other gases. The hydrogen enters the hydrogen storage tank 16, the carbon monoxide enters the CO storage tank 17, and the other substances are treated as by-products.

[0059] After the reaction, the molten salt leaves the pyrolysis reactor 2 through the molten salt outlet 203 in the upper part, and enters the carbon black filter 9 through the inlet of the carbon black filter 9 on the pipeline to remove carbon black and other impurities. Then, the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 and calcium oxide enter the molten salt storage tank 8 from the outlet of the carbon black filter 9 through heating and reuse.

[0060] At night or on cloudy days, close valve 7 on the pipeline connecting the trough-type concentrating solar collector 6 and open valve 7 on the pipeline connecting the electric heating device 3. Due to the influence of the external environment at this time, solar energy cannot be directly absorbed. Instead, the electrical energy stored in the battery 4 through the photovoltaic panel 5 during the day can be used to heat the molten salt using the electric heating device 3. Some subsequent processes are the same as during the day.

[0061] Method Example 1

[0062] This embodiment provides a process for accelerating hydrogen production from waste tire pyrolysis using solar energy, as shown in the attached diagram. Figure 1 As shown,

[0063] Step S1. Preparation of molten salt and waste tire pellets: Accurately weigh 32.1% Li₂CO₃, 33.4% Na₂CO₃, and 34.5% K₂CO₃ (wt%), mix the three substances evenly, and heat to 600℃ at a heating rate of 10℃ / min. Hold at this temperature for 6 hours, then allow to cool naturally to room temperature. Finally, crush the cooled mixture and pass it through a 60-mesh sieve to obtain a ternary mixed molten salt of Li₂CO₃-Na₂CO₃-K₂CO₃. Remove the steel wires from the waste rubber tires and crush them into pellets using a shredder to obtain waste tire pellets for later use.

[0064] Step S2: Waste Tire Pyrolysis: The prepared Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt and calcium oxide were added to the reactor, wherein the amount of calcium oxide added was 9% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt; and the amount of waste tire particles added was 20% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt. The pyrolysis reaction of the waste tire particles was carried out under a protective atmosphere, with nitrogen as the protective gas, and the introduction rate was 25 ml / min. The pyrolysis reaction adopts a gradient heating method with a heating rate of 20℃ / min. The temperature is first raised to 700℃ and held for 0.5h, then raised to 770℃ and held for 8min to cause the waste tire particles to undergo a pyrolysis reaction, producing gaseous substances containing H2, small molecule aliphatic hydrocarbons (such as methane, ethane, ethylene, propane, and propylene), aromatic hydrocarbons (such as benzene, toluene, and xylene), CO, and CO2. Among them, CO and CO2 are acidic gases. The ash produced at the same time (including elemental metals and inorganic non-metallic components) and some acidic gases are absorbed by the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 and calcium oxide to obtain a mixture.

[0065] Step S3. Catalytic reforming:

[0066] The gaseous substance generated in step S2 was passed into a 5 mol / L sodium hydroxide solution, followed by condensation and drying. The condensation temperature was controlled at 6°C, and the gas flow rate was 25 ml / min. Finally, the treated gaseous substance was catalytically reformed under the action of a composite metal oxide nickel-magnesium-aluminum catalyst to obtain hydrogen and other gases, which were then classified and stored. Hydrogen was stored in a hydrogen storage tank, nitric oxide in a CO storage tank, and other byproducts were further processed. The composite metal oxide nickel-magnesium-aluminum catalyst contains n(Ni) 2+ ):n(Mg 2+ ):n(Al 3+ = 0.5:1.2:1.

[0067] Step S4. Recycling of molten salt and calcium oxide:

[0068] The mixture from step S2 is processed to remove the carbon black and then returned to the molten salt storage tank for use in the next pyrolysis reaction.

[0069] In this embodiment, a solar-powered self-priming agitator accelerates the hydrogen production process from waste tire pyrolysis. A specific ratio of mixed molten salt and calcium oxide absorbs the ash and some acidic gases generated during pyrolysis. Following catalytic reforming and other steps, the hydrogen yield and purity are effectively improved. Simultaneously, the molten salt and calcium oxide are recycled, reducing production costs and resulting in significant economic and environmental benefits. In practical applications, the parameters of each step can be appropriately adjusted and optimized based on the source and composition of the waste tires, as well as the required hydrogen yield and quality, to achieve the best pyrolysis hydrogen production effect.

[0070] Method Example 2

[0071] The difference between this method embodiment and Method Embodiment 1 is that in this method embodiment, step S2, waste tire pyrolysis, involves adding the prepared Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt and calcium oxide to the reactor. The amount of calcium oxide added is 8% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt, and the amount of waste tire particles added is 20% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt. The pyrolysis reaction of the waste tire particles is carried out under a protective atmosphere, with nitrogen as the protective gas, and the introduction rate is 25 ml / min. The pyrolysis reaction adopts a gradient heating method with a heating rate of 20℃ / min. The temperature is first raised to 700℃ and held for 0.5h, then raised to 800℃ and held for 5min to cause the waste tire particles to undergo a pyrolysis reaction, producing gaseous substances containing H2, small molecule aliphatic hydrocarbons (such as methane, ethane, ethylene, propane, and propylene), aromatic hydrocarbons (such as benzene, toluene, and xylene), CO, and CO2. Among them, CO and CO2 are acidic gases. The ash produced at the same time (including elemental metals and inorganic non-metallic components) and some acidic gases are absorbed by the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 and calcium oxide to obtain a mixture.

[0072] Method Example 3

[0073] The difference between this method embodiment and Method Embodiment 1 is that in this method embodiment, step S2, waste tire pyrolysis, involves adding the prepared Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt and calcium oxide to the reactor. The amount of calcium oxide added is 10% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt, and the amount of waste tire particles added is 20% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt. The pyrolysis reaction of the waste tire particles is carried out under a protective atmosphere, with nitrogen as the protective gas, and the introduction rate is 25 ml / min. The pyrolysis reaction adopts a gradient heating method with a heating rate of 20℃ / min. The temperature is first raised to 700℃ and held for 0.5h, then raised to 750℃ and held for 10min to cause the waste tire particles to undergo a pyrolysis reaction, producing gaseous substances containing H2, small molecule aliphatic hydrocarbons (such as methane, ethane, ethylene, propane, and propylene), aromatic hydrocarbons (such as benzene, toluene, and xylene), CO, and CO2. Among them, CO and CO2 are acidic gases. The ash produced at the same time (including metallic elements and inorganic non-metallic components) and some acidic gases are absorbed by the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 and calcium oxide to obtain a mixture.

[0074] Method Example 4

[0075] The difference between this method embodiment and Example 1 is as follows: Step S1. Preparation of molten salt and waste tire granules: Accurately weigh 20% Li2CO3, 30% Na2CO3, and 50% K2CO3 (wt%), mix the three substances evenly, heat to 600℃ at a heating rate of 10℃ / min, hold at that temperature for 6 hours, then allow to cool naturally to room temperature. Finally, crush the cooled mixture and pass it through a 60-mesh sieve to obtain a ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3. Remove the steel wires from the waste rubber tires, and use a shredder to crush the waste tires into granules to obtain waste tire granules for later use.

[0076] Method Example 5

[0077] The difference between this method embodiment and Example 1 is as follows: Step S1. Preparation of molten salt and waste tire granules: Accurately weigh 50% Li2CO3, 20% Na2CO3, and 50% K2CO3 (wt%), mix the three substances evenly, heat to 600℃ at a heating rate of 10℃ / min, hold at that temperature for 6 hours, then allow to cool naturally to room temperature. Finally, crush the cooled mixture and pass it through a 60-mesh sieve to obtain a ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3. Remove the steel wires from the waste rubber tires, and use a shredder to crush the waste tires into granules to obtain waste tire granules for later use.

[0078] Method Example 6

[0079] The difference between this method embodiment and Example 1 is as follows: S1. Preparation of molten salt and waste tire pellets: Accurately weigh 30% Li2CO3, 50% Na2CO3, and 20% K2CO3 (wt%), mix the three substances evenly, heat to 600℃ at a heating rate of 10℃ / min, hold at that temperature for 6 hours, then allow to cool naturally to room temperature. Finally, crush the cooled mixture and pass it through a 60-mesh sieve to obtain a ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3. Remove the steel wires from the waste rubber tires, and use a shredder to crush the waste tires into granules to obtain waste tire pellets for later use.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Method Example 1 is that in step S2, waste tire pyrolysis: the prepared Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt and calcium oxide are added to the reactor, wherein the amount of calcium oxide added is 9% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt; and the amount of waste tire particles added is 20% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt. The pyrolysis reaction of the waste tire particles is carried out under a protective atmosphere, with nitrogen as the protective gas, and the introduction rate is 25 ml / min. The pyrolysis reaction involves directly heating to 770℃ and holding at that temperature for 38 minutes to cause the waste tire particles to undergo a pyrolysis reaction, producing gaseous substances containing H2, small molecule aliphatic hydrocarbons (such as methane, ethane, ethylene, propane, and propylene), aromatic hydrocarbons (such as benzene, toluene, and xylene), CO, and CO2. The gas yield is 0.39 g / g tire. Among them, CO and CO2 are acidic gases. The ash produced at the same time (including elemental metals and inorganic non-metallic components) and some of the acidic gases are absorbed by the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 and calcium oxide to obtain a mixture.

[0082] Comparative Example 2

[0083] The difference between this comparative example and Method Example 1 is that in step S2, waste tire pyrolysis: the prepared Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt is added to the reactor, and the amount of waste tire particles added is 20% of the mass of the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt. The pyrolysis reaction of the waste tire particles is carried out under a protective atmosphere, with nitrogen as the protective gas, and the introduction rate is 25 ml / min. The pyrolysis reaction adopts a gradient heating method with a heating rate of 20℃ / min. The temperature is first raised to 700℃ and held for 0.5h, then raised to 770℃ and held for 8min to cause the waste tire particles to undergo a pyrolysis reaction, producing gaseous substances containing H2, small molecule aliphatic hydrocarbons (such as methane, ethane, ethylene, propane, and propylene), aromatic hydrocarbons (such as benzene, toluene, and xylene), CO, and CO2. Among them, CO and CO2 are acidic gases. The ash produced at the same time (including elemental metals and inorganic non-metallic components) and some acidic gases are absorbed by the ternary mixed molten salt of Li2CO3-Na2CO3-K2CO3 and calcium oxide to obtain a mixture.

[0084] Performance testing

[0085] The composition of the gas after catalytic integration is shown in Table 1 below.

[0086] Table 1

[0087]

[0088]

[0089] Results Analysis

[0090] As can be seen from Examples 1-6, Comparative Examples 1-2, and Table 1, by employing the method and apparatus of this application, solar energy is used to heat molten salt, reducing costs and being environmentally friendly. The molten salt exhibits good heat transfer performance, improving pyrolysis efficiency and reducing pollution. The addition of a self-priming stirrer to the pyrolysis reactor, along with hemispherical protrusions on the inner wall of the baffles, enhances mixing and heat transfer efficiency. The addition of calcium oxide to the molten salt reduces polluting gases, maintains the performance of the molten salt, improves hydrogen selectivity, and extends catalyst life.

[0091] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A process for coupling solar energy to accelerate the pyrolysis of waste tires for hydrogen production, characterized in that, The method comprises the following steps: Step S1. Preparing molten salt and waste tire particles Li2CO3, K2CO3, Na2CO3 are mixed uniformly, heated, then kept warm and cooled to room temperature, finally crushed and sieved to obtain Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt; The steel wires in the waste tires are stripped off and crushed to obtain waste tire particles; The above preparation of molten salt and waste tire particles is not in chronological order; Step S2. Waste tire pyrolysis Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt, calcium oxide and waste tire particles are added into the reactor, and the waste tire particles are pyrolyzed under a protective atmosphere to produce gaseous substances and ash; the gaseous substances are H2, small molecule aliphatic hydrocarbons, aromatic hydrocarbons, CO and CO2, and the ash includes elemental metals and inorganic non-metal components; The amount of calcium oxide added in step S2 is 8-10% of the mass of Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt; the amount of waste tire particles added is 20% of the mass of Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt; the protective gas is nitrogen, and the inlet speed is 25 ml / min; the pyrolysis reaction is gradient heating, and the heating rate is 20℃ / min, first heated to 700℃, kept warm for 0.5h, then heated to 750-800℃, kept warm for 5-10min; The process of utilizing solar energy during waste tire pyrolysis: open the valve connected to the pipe of the trough-type concentrating collector, and the system relies on the trough-type concentrating collector to absorb solar energy and convert it into heat to transfer to the molten salt and calcium oxide in the pipe. The molten salt and calcium oxide enter the molten salt storage tank, and the molten salt enters the reaction kettle of the pyrolysis reactor through the molten salt inlet. At the same time, the waste tire passes through the tire crusher and then enters the reaction kettle of the pyrolysis reactor through the solid waste inlet. The calcium oxide enters the reaction kettle of the pyrolysis reactor through the solid waste inlet; Step S3. Catalytic reforming The gaseous substances in step S2 are introduced into an alkaline liquid for purification, then condensed and impurities are removed, and finally catalytic reforming is carried out under the action of a composite metal oxide nickel-magnesium-aluminum catalyst to obtain hydrogen and other gases for classification and storage; Step S4. Recycling of molten salt and calcium oxide The ash in step S2 is absorbed by Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt and calcium oxide to obtain a mixture, the mixture is removed from the carbon black, and returned to the molten salt storage tank.

2. The process for hydrogen production by coupling solar energy with accelerated pyrolysis of waste tires according to claim 1, characterized in that, In step S1, the Li2CO3-Na2CO3-K2CO3 ternary mixed molten salt comprises 20-50wt% Li2CO3, 20-50wt% Na2CO3 and 20-50wt% K2CO3.

3. The process for hydrogen production by coupling solar energy with accelerated pyrolysis of waste tires according to claim 1, characterized in that, In step S1, Li2CO3, K2CO3 and Na2CO3 are heated to 600℃ at a heating rate of 10℃ / min, kept warm for 6h, and sieved through a 60 mesh sieve; the waste tire particles are rubber tires.

4. The process for hydrogen production by coupling solar energy with accelerated pyrolysis of waste tires according to claim 1, characterized in that, The small molecule aliphatic hydrocarbons include methane, ethane, ethylene, propane and propylene; the aromatic hydrocarbons include benzene, toluene and xylene.

5. The process for hydrogen production by coupling solar energy with accelerated pyrolysis of waste tires according to claim 1, wherein, The alkaline liquid in the step S3 is a 5 mol / L sodium hydroxide solution, the condensation temperature is 6°C, the gas flow rate of the gaseous substance is 25 ml / min, and the composite metal oxide nickel-magnesium-aluminum catalyst has n(Ni 2+ ):n(Mg 2+ ):n(Al 3+ )=0.5:1.2:

1.

6. The process for hydrogen production by coupling solar energy with accelerated pyrolysis of waste tires according to claim 1, wherein, The device for hydrogen production by pyrolysis process comprises a pyrolysis reactor (2), a solid waste inlet (206), a gas inlet (205) and a gas outlet (201) arranged above the pyrolysis reactor (2), a molten salt inlet (202) arranged below the sidewall of the pyrolysis reactor (2), a molten salt outlet (203) arranged below the sidewall of the pyrolysis reactor (2), the solid waste inlet (206) being communicated with a tire crusher (1), the molten salt inlet (202) being communicated with an inlet of a molten salt storage tank (8), the molten salt storage tank (8) being further provided with an outlet, the molten salt outlet (203) being communicated with a pipeline, the pipeline being provided with a carbon black filter (9), the carbon black filter (9) being provided with a filter outlet and a filter inlet, the filter inlet being communicated with the molten salt outlet (203), the filter outlet being communicated with two parallel pipelines, the two parallel pipelines being provided with valves (7), one of the two parallel pipelines being connected with an electric heating device (3), the other pipeline being connected with a trough type concentrating collector (6), the two parallel pipelines being communicated with the molten salt inlet (202) after being connected in parallel.

7. The process of claim 6, wherein the process is coupled with solar energy. The electric heating device (3) is further connected in series with a photovoltaic panel (5) and a storage battery (4), the photovoltaic panel (5) is used for storing solar energy into electric energy in the storage battery (4), the storage battery (4) is used for heating the molten salt by the electric heating device (3) at night or on cloudy days; the gas outlet (201) of the pyrolysis reactor (2) is communicated with a gas treatment device (11), a condenser (12), a catalytic reforming reactor (13) and a gas separator (15) in sequence along the gas flow direction, the gas separator (15) is further communicated with a hydrogen storage tank (16) and a CO storage tank (17) respectively, the pipeline connected between the catalytic reforming reactor (13) and the gas separator (15) is provided with a gas detection system (14) for detecting the gas composition, and the catalytic reforming reactor (13) is externally provided with a heating layer (214).

8. The process of claim 6, wherein the process is coupled with solar energy to accelerate the pyrolysis of waste tires to produce hydrogen. The pyrolysis reactor (2) comprises a motor (204) arranged at the top end and a self-suction stirrer (210) arranged inside the pyrolysis reactor (2), the motor (204) is connected with the self-suction stirrer (210) through a shaft coupling (2101), the self-suction stirrer (210) comprises a hollow transmission shaft (211), a self-suction impeller (2102) arranged on the hollow transmission shaft (211) close to the motor (204) and an axial flow paddle (2103) arranged on the hollow transmission shaft (211) away from the motor (204), a sleeve (2104) is welded on the paddle of the axial flow paddle (2103), the radius of the sleeve (2104) is smaller than the radius of the paddle, and the sleeve (2104) extends to the bottom of the pyrolysis reactor (2).

9. The process of claim 6, wherein the process is coupled with solar energy to accelerate the pyrolysis of waste tires to produce hydrogen. The pyrolysis reactor (2) is internally provided with a reaction kettle (208), the outside of the reaction kettle (208) is provided with a heating layer (214), the inside of the reaction kettle (208) is provided with a curved baffle (209) along the axial direction, the curved baffle (209) is uniformly provided with a hemispherical protrusion on the surface, for increasing the heat transfer area, increasing the waste tire cracking speed, the top of the reaction kettle (208) is also provided with a demister (207) for removing foam; The pyrolysis reactor (2) is also provided with a thermocouple (213) and a pressure gauge (212) for detecting the temperature inside the reaction kettle (208).

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