Waste rubber and plastic pyrolysis system and application thereof

Abstract

The invention provides a waste rubber and plastic pyrolysis system and application thereof.The waste rubber and plastic pyrolysis system comprises a feeding unit comprising a feeding bin, a material conveying mechanism and an anaerobic protection mechanism, a pyrolysis reaction unit comprising a first-stage pyrolysis reactor and a second-stage pyrolysis reactor, and each pyrolysis reactor at least comprises a heating cavity, a material conveying device and a heating source; the heating cavity provides a closed high-temperature environment under the action of the heating source, the material conveying mechanism pushes materials in the heating cavity in the preset direction, and an outlet of the first-stage pyrolysis reactor communicates with an inlet of the second-stage pyrolysis reactor, so that the materials sequentially pass through the first-stage pyrolysis reactor and the second-stage pyrolysis reactor to be subjected to multi-stage pyrolysis. The product recycling structure comprises a pyrolysis gas purifying and condensing device, the pyrolysis gas purifying and condensing device is connected with the second-stage pyrolysis reactor, and by applying the technical scheme, the technical problem that in the prior art, waste rubber and plastic pyrolysis and equipment carbon residue treatment are difficult can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste rubber and plastic chemical recycling, in particular to a waste rubber and plastic pyrolysis system and application thereof. BACKGROUND

[0002] In recent years, with the continuous expansion of China's manufacturing industry and consumer market, the rubber and plastic product industry has developed rapidly, and the amount of waste rubber and plastic (waste rubber and plastic) has also increased dramatically. If these wastes are not properly treated, not only will they occupy a large amount of land resources and form "white pollution", but also they will cause long-term and deep harm to soil, water and air due to their difficulty in natural degradation. Therefore, promoting the harmless and resourceful treatment of waste rubber and plastic has become a key issue to be solved for China to develop circular economy and achieve the "double carbon" goal.

[0003] At present, waste rubber and plastic recycling includes physical recycling and chemical recycling. Physical recycling technology and market are relatively mature, and chemical recycling can realize resource utilization of low-value and mixed plastics that cannot be processed as garbage by physical recycling. Pyrolysis is the mainstream technology for chemical recycling of waste rubber and plastic, and the pyrolysis reactor mainly adopts rotary kiln and fluidized bed forms.

[0004] Physical recycling: Through physical processes such as cleaning, crushing, and melt granulation, waste rubber and plastic are reproduced into low-grade plastic products. This technology is mature and widely used in the market, but it is mainly suitable for single and clean waste, and there is a problem of downcycling, with limited product value.

[0005] Chemical recycling: It is considered as the fundamental way to solve low-value, mixed, and heavily polluted waste rubber and plastic. It breaks down high molecular polymers into small molecular monomers, fuel oil, or chemical raw materials through chemical methods, realizes "upcycling", and is an important supplement and upgrading direction of physical recycling. Pyrolysis technology, as the mainstream path of chemical recycling, is a process that breaks down the macromolecular chains of waste rubber and plastic into pyrolysis oil, pyrolysis gas, and solid carbon residue under anaerobic or oxygen-poor conditions by heating to a certain temperature. Common reactor forms include rotary kiln (simple operation and strong adaptability) and fluidized bed.

[0006] Although pyrolysis technology has achieved large-scale industrial application, its long-term stable operation and economy still face a series of severe technical bottlenecks, the core problems of which are rooted in the characteristics of waste rubber and plastic materials themselves: 1. Low heat transfer efficiency and uneven reaction; 2. Uneven heat transfer leads to local overheating (hot spots) or insufficient heating (cold zones). Hot spots promote excessive cracking to form carbon, and cold zones make the reaction incomplete, leaving large molecular substances. The above effects together cause the deposition of viscous intermediate products and carbon particles on the inner wall of the reactor, stirring device, etc., forming a hard coking and carbon layer. This coking layer acts as an "insulation layer", further worsening the heat transfer efficiency, forming a vicious cycle. 3. Limited by the non-uniform heat field, the pyrolysis reaction process is difficult to accurately control, resulting in unstable yield and quality of the target product (usually pyrolysis oil). The oil may contain a large amount of heavy components and impurities, which need to be refined through a complex subsequent process, increasing the cost.

[0007] In summary, due to the poor heat transfer performance of waste rubber and plastic, the heating in the pyrolysis furnace is uneven, the pyrolysis reaction process is not uniform, coking and carbon deposition easily occur on the surface of the furnace wall, the heat conduction efficiency is low, and the system cannot run stably for a long period of time, which is economically inefficient. At the same time, the heating area of the pyrolysis furnace is small, the heat transfer is uneven, the completeness of the pyrolysis reaction is affected, and the product yield is low.

[0008] Pyrolysis technology has achieved industrial application, but the existing waste rubber and plastic pyrolysis device generally has the problem of difficult carbon residue treatment, and the heat source in the pyrolysis process needs to consume a part of the pyrolysis gas product, so in the pyrolysis process, the generated carbon residue can be treated synchronously and efficiently in the pyrolysis process, and the energy released in the treatment process is used to provide heat for the pyrolysis reaction, forming an internal energy cycle. This not only reduces or even replaces the consumption of pyrolysis gas, but also completely solves the problem of carbon residue outlet, realizes "waste treatment with waste", and significantly improves the energy efficiency and economic benefit of the system. Furthermore, the technical personnel in the field are faced with the problem of treating the generated carbon residue, reducing the consumption of pyrolysis gas, solving the problem of pyrolysis carbon residue treatment, and improving the energy efficiency of the waste rubber and plastic pyrolysis system, which has become an urgent need. SUMMARY

[0009] The present application aims to solve the problem of difficult carbon residue treatment of existing waste rubber and plastic pyrolysis equipment, improve the energy efficiency of the pyrolysis system, and design a plastic pyrolysis system with simple structure, high heat transfer efficiency, low coking rate, high oil yield, long running period, high energy utilization rate and low running cost.

[0010] The present application adopts the following technical scheme: a waste rubber and plastic pyrolysis system, comprising: - a feeding unit, the feeding unit comprising a feeding bin, a material conveying mechanism and an anaerobic protection mechanism, the material conveying device is used to convey the waste rubber and plastic material from the feeding bin to the pyrolysis reaction unit under the anaerobic environment provided by the anaerobic protection device; - a pyrolysis reaction unit, the pyrolysis reaction unit comprising a primary pyrolysis reactor and a secondary pyrolysis reactor, each of the pyrolysis reactors comprising at least one heating cavity, a material conveying mechanism and a heating source, the heating cavity providing a closed high-temperature environment under the action of the heating source, the material conveying mechanism advancing the material in a predetermined direction within the heating cavity, the outlet of the primary pyrolysis reactor being in communication with the inlet of the secondary pyrolysis reactor, so that the material sequentially passes through the primary pyrolysis reactor and the secondary pyrolysis reactor for multi-stage pyrolysis; - a product recovery unit, the product recovery unit comprising a pyrolysis gas purification and condensation unit, the pyrolysis gas purification and condensation unit being connected to the secondary pyrolysis reactor for receiving and purifying the pyrolysis gas generated by the secondary pyrolysis reactor, while condensing the pyrolysis gas into pyrolysis oil, the purification process further comprising separating carbon residue particles, wherein the separation of the carbon residue particles is achieved based on the movement trajectory of the pyrolysis gas within the purification unit.

[0011] Further, the material conveying mechanism is a progressive variable-pitch screw feeder, the pitch of the screw feeder gradually decreasing along the material conveying direction.

[0012] Further, the primary pyrolysis reactor is internally provided with a first screw blade, the first screw blade advancing the material within the heating cavity; the secondary pyrolysis reactor is internally provided with a second screw blade, the second screw blade advancing the material within the heating cavity; the first screw blade and the second screw blade are precisely controlled with the gap between the heating cavity bottom to remove internal wall coking.

[0013] Further, a discharge port or a rotary valve is provided between the primary pyrolysis reactor and the secondary pyrolysis reactor to ensure smooth transfer of the material.

[0014] Further, the pyrolysis gas purification and condensation unit further recovers part of the pyrolysis gas as supplemental fuel.

[0015] Further, the rotation speed of the screw feeder and the temperature distribution of the heating cavity are precisely controlled to adjust the residence time of the material at different temperature stages.

[0016] The application can also adopt a waste rubber and plastic pyrolysis production line, comprising: a waste rubber and plastic pyrolysis system and a production line body, the production line body comprising a crushing unit, a pretreatment unit, the waste rubber and plastic pyrolysis system and a subsequent treatment unit, the crushing unit being connected to the pretreatment unit, the pretreatment unit being connected to the feeding unit, and the subsequent treatment unit being connected to the product recovery unit.

[0017] The present invention can also employ a waste rubber and plastic chemical recycling system, comprising: a waste rubber and plastic pyrolysis production line and a recycling structure. The recycling structure includes a product storage unit, a product reuse unit, and an energy recycling unit. The product storage unit is connected to the subsequent processing unit of the waste rubber and plastic pyrolysis production line and is used to store pyrolysis oil and pyrolysis gas. The product reuse unit is connected to the product storage unit and is used to convert the pyrolysis oil and pyrolysis gas into usable products. The energy recycling unit is connected to the product storage unit and the pyrolysis reaction structure and is used to use a portion of the pyrolysis gas as supplementary fuel for the combustion device to provide the heat required by the pyrolysis reaction structure.

[0018] Beneficial effects 1. This invention employs a two-stage pyrolysis reactor with different temperatures in each stage. Waste rubber and plastics are first pyrolyzed at a low temperature in the first-stage reactor, prioritizing the easily decomposable waste rubber and plastics. Then, the less easily decomposable waste rubber and plastics undergo high-temperature pyrolysis in the second-stage reactor. This two-stage pyrolysis increases the pyrolysis reaction time and heating area, improving production speed and ensuring uniform heating of the waste rubber and plastics within the reactor. This prevents coking and carbonization while simultaneously increasing the oil recovery rate.

[0019] 2. The carbon residue generated from the pyrolysis of waste rubber and plastics in this invention enters the fluidized bed combustion device to provide most of the heat for the pyrolysis of waste rubber and plastics. This not only solves the problem of carbon residue treatment, but also reduces system energy consumption, reduces the consumption of pyrolysis gas products, and improves energy utilization.

[0020] 3. In this invention, the high-temperature flue gas enters the fluidized bed combustion device for recirculation and re-combustion, which reduces nitrogen oxides in the high-temperature flue gas and lowers the cost of flue gas purification.

[0021] 4. The pyrolysis system of this invention has a simple structure, is stable and reliable, has a low coking rate, high thermal efficiency, does not produce difficult-to-treat carbon slag, and has low operating costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an embodiment of the waste rubber and plastic pyrolysis system of the present invention.

[0023] Figure label: The components are as follows: 1. Feed hopper; 2. Screw feeder; 3. Nitrogen inlet; 4. Primary pyrolysis reactor; 5. Flue gas outlet; 6. Outer cylinder one; 7. Inner cylinder one; 8. Screw blade one; 9. Rotating shaft one; 10. Drive motor one; 11. Unloading mechanism; 12. Flue gas passage; 13. Drive motor two; 14. Secondary pyrolysis reactor; 15. Outer cylinder two; 16. Inner cylinder two; 17. Rotating shaft two; 18. Screw blade two; 19. Slag outlet; 20. Return feeder one; 21. Pyrolysis gas outlet; 22. Cyclone dust collector; 23. Return feeder two; 24. Condensation tower; 25. Fluidized bed. DETAILED DESCRIPTION

[0024] It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0025] It should be noted that all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs, unless otherwise specified.

[0026] In the present application, unless otherwise specified, the orientation words such as "up, down, top, bottom" are generally directed to the directions shown in the drawings, or are directed to the vertical, perpendicular or gravity directions of the components themselves; similarly, for the convenience of understanding and description, "inner, outer" refers to the inner and outer relative to the contour of the components themselves, but the above orientation words are not used to limit the present application.

[0027] The present application discloses a waste rubber and plastic pyrolysis system, comprising: a feeding unit, the feeding unit comprising a feeding bin, a material conveying mechanism and an anaerobic protection mechanism, the material conveying mechanism being used to convey the waste rubber and plastic material from the feeding bin to the pyrolysis reaction structure under the anaerobic environment provided by the anaerobic protection mechanism; a pyrolysis reaction unit, the pyrolysis reaction unit comprising a primary pyrolysis reactor and a secondary pyrolysis reactor, each pyrolysis reactor comprising at least one heating cavity, a material advancing mechanism and a heating source, the heating cavity providing a closed high-temperature environment under the action of the heating source, the material advancing mechanism advancing the material in a predetermined direction within the heating cavity, the outlet of the primary pyrolysis reaction mechanism being in communication with the inlet of the secondary pyrolysis reaction mechanism, so that the material sequentially passes through the primary pyrolysis reactor and the secondary pyrolysis reactor for multistage pyrolysis; a product recovery unit, the product recovery unit comprising a pyrolysis gas purification and condensation mechanism, the pyrolysis gas purification and condensation mechanism being connected with the secondary pyrolysis reactor, used to receive and purify the pyrolysis gas generated by the secondary pyrolysis reactor, and simultaneously condense the pyrolysis gas into pyrolysis oil, the purification process further comprising separating carbon residue particles, wherein the separation of the carbon residue particles is realized based on the movement trajectory of the pyrolysis gas within the purification device.

[0028] The application of the technical scheme of the embodiment, the waste rubber and plastic pyrolysis system device solves the problems of difficult carbon residue treatment of waste rubber and plastic pyrolysis equipment and energy efficiency improvement through the synergistic effect of the unique feeding unit, pyrolysis reaction unit and product recovery unit. In the feeding unit, the material conveying unit transports the waste rubber and plastic from the feed bin to the pyrolysis reactor in the environment created by the anaerobic protection mechanism, ensuring the anaerobic condition of the pyrolysis process and avoiding the side reactions caused by oxygen, thereby improving the pyrolysis efficiency. The first and second pyrolysis reactors of the pyrolysis reaction unit are designed in series, and the material is pushed in the heating cavity by the material pushing mechanism, realizing multi-stage pyrolysis of the material and ensuring the thoroughness of the pyrolysis, thereby improving the yield of pyrolysis oil and pyrolysis gas. The pyrolysis gas purification and condensation device in the product recovery unit not only condenses the pyrolysis gas to recover the pyrolysis oil, but also effectively separates the carbon residue particles, reducing the fuel demand of the fluidized bed combustion device, thereby reducing the consumption of pyrolysis gas and improving the energy utilization rate of the entire system. At the same time, the separation of carbon residue particles based on the movement trajectory of pyrolysis gas in the purification device further promotes the full recovery and utilization of pyrolysis gas, reduces NOx emissions, and meets the needs of environmental protection. In summary, the technical scheme of the embodiment significantly improves the energy efficiency and economy of the waste rubber and plastic pyrolysis system, while also taking into account the environmental benefits.

[0029] Further, in the present embodiment, a first screw blade is arranged inside the first pyrolysis reactor.

[0030] In the present embodiment, the first pyrolysis reactor 4 is equipped with a first screw blade 8 arranged inside the heating cavity, which functions to push the material forward from left to right. The material is continuously pushed during this process, ensuring uniform distribution and continuous pyrolysis of the waste rubber and plastic in a high-temperature anaerobic environment. The design of the first screw blade 8 promotes full contact between the material and the inner wall of the heating cavity, improving heat transfer efficiency and also having the function of cleaning the coking on the inner wall, thereby reducing the coking rate and prolonging the operating cycle of the equipment. The waste rubber and plastic, guided by the first screw blade 8, undergoes the entire heating path of the first pyrolysis reactor 4, ensuring the full pyrolysis reaction and improving the yield of pyrolysis oil. The implementation results show that this design can effectively improve the pyrolysis efficiency of the material in the reactor, reduce energy consumption, and simplify the subsequent treatment of carbon residue, thereby improving the energy efficiency and economy of the waste rubber and plastic pyrolysis system as a whole. In other configurations of the present embodiment, the shape and size of the first screw blade 8 can be adjusted according to the properties of the material and the requirements of the pyrolysis process to optimize its role in material pushing and coking cleaning. Of course, the precision of the cooperation between the first screw blade 8 and the first rotating shaft 9, as well as the gap design between the first screw blade 8 and the inner cylinder 7, are also key factors to ensure the stability and efficiency of the equipment. By precisely controlling these parameters, the conversion rate of the material during the pyrolysis process can be further improved, achieving stable production of high-quality pyrolysis products.

[0031] Further, in this embodiment, the secondary pyrolysis reactor is internally provided with a second spiral blade, which pushes the material forward inside the heating cavity.

[0032] In this embodiment, the secondary pyrolysis reactor is internally provided with a second spiral blade 18, which makes the material inside the heating cavity of the secondary pyrolysis reactor 14 advance along the guide of the second spiral blade 18 and move forward. The second spiral blade 18, driven by the second rotating shaft 17, can effectively push the material to uniformly advance under high temperature conditions, ensuring that the residence time and heating degree of the material in the secondary pyrolysis reactor are accurately controlled. This technical solution increases the movement trajectory of the material in the heating cavity, expands the contact area between the material and the heat source, and thus improves the pyrolysis efficiency and product quality. At the same time, the second spiral blade 18 can also assist in cleaning the coking that may form on the wall of the inner cylinder 16, maintaining the cleanliness of the reactor interior and avoiding the risk of heat transfer efficiency reduction and blockage due to coking, thereby prolonging the operation cycle of the equipment and reducing maintenance costs. The strategy of pushing the material forward by the second spiral blade realizes uniform heating and decomposition of the material in a high-temperature environment, promotes the improvement of pyrolysis gas and pyrolysis oil yield, and also ensures the continuity and stability of the entire pyrolysis process.

[0033] Further, in this embodiment, the gap between the first spiral blade and the second spiral blade and the bottom of the heating cavity is accurately controlled to remove the coking on the inner wall.

[0034] In this embodiment, the gap between the first spiral blade 8 and the second spiral blade 18 and the bottom of the heating cavity is accurately controlled to be between 4 to 8 mm, which ensures that at the operating temperature, both the loss caused by excessive friction of the material with the bottom of the heating cavity and the material retention, and the effective removal of the coking that may form on the inner wall. Through the rotation of the spiral blade, not only the material is pushed forward, but also the inner wall is periodically cleaned by the gap between the spiral blade and the cavity bottom, thereby significantly reducing the risk of heat efficiency reduction and blockage due to coking, improving the operation stability and economy of the pyrolysis system. The precise gap control combined with the structure of the spiral blade realizes the dual function of material conveying and wall cleaning, ensuring uniform heating and sufficient pyrolysis of the material during the heating process, thereby improving the yield and quality of pyrolysis oil and pyrolysis gas, and prolonging the continuous operation time of the equipment.

[0035] Further, in this embodiment, the particle size of the waste rubber and plastic material received by the feeding bin is less than 10 mm.

[0036] In this embodiment, the particle size of the waste rubber and plastic material received by the feed bin is limited to less than 10 mm. This standardization process ensures uniform heating and efficient pyrolysis of the material during the pyrolysis process, avoiding the problem of low internal heat transfer efficiency and incomplete pyrolysis caused by oversized material. By controlling the particle size of the material, waste rubber and plastic can move more smoothly in the primary and secondary pyrolysis reactors, reducing the risk of blockage, while the spiral blades can also more effectively remove the coke on the inner wall when pushing the material forward, maintaining the long-term stable operation of the reactor. In addition, smaller material particle size also promotes the generation of pyrolysis gas, improves the yield and quality of pyrolysis oil, and achieves higher energy utilization and economic benefits. The standardization of the material particle size, combined with the overall design of the pyrolysis system, can ensure that the pyrolysis process of waste rubber and plastic achieves resource recovery under the premise of environmental protection and energy saving.

[0037] Further, in this embodiment, the pyrolysis gas purification and condensation device also recovers part of the pyrolysis gas as supplementary fuel.

[0038] In this embodiment, the pyrolysis gas purification and condensation device recovers part of the pyrolysis gas as supplementary fuel. Specifically, after the pyrolysis gas removes solid impurities through the cyclone dust collector 22, it is then condensed through the condensation tower 24, separating out pyrolysis oil and uncondensed pyrolysis gas. The uncondensed pyrolysis gas is rich in light component hydrocarbons and has a high calorific value, making it a good choice for supplementary fuel. This part of the pyrolysis gas is then sent back to the fluidized bed 25 to be burned together with the carbon residue, providing continuous heat to the pyrolysis unit. In this way, not only does it improve the energy self-sufficiency of the system and reduce dependence on external fuel, but it also realizes the recycling of pyrolysis gas, optimizes the energy structure, and reduces operating costs. The recycling mechanism of pyrolysis gas ensures the stability and thermal efficiency of combustion, while reducing the complexity of carbon residue disposal, overall improving the economic and environmental performance of the waste rubber and plastic pyrolysis system. While ensuring complete combustion, appropriate measures are taken to reduce the negative impact on the fluidized bed combustion device, such as selecting an appropriate combustion temperature, regular maintenance to remove ash and coke, and controlling the combustion conditions by recycling flue gas back to the combustion device. These measures work together to ensure the long-term stable operation of the fluidized bed combustion device and the flue gas emissions meet environmental standards.

[0039] In this embodiment, the pyrolysis gas purification and condensation device recovers part of the pyrolysis gas as supplementary fuel. After removing solid impurities through the cyclone dust collector 22, the pyrolysis gas enters the condensation tower 24 for condensation, separating pyrolysis oil and incompletely condensed pyrolysis gas. Among them, the incompletely condensed pyrolysis gas, rich in high-calorie light component hydrocarbons, is sent back to the fluidized bed 25 to mix and burn with carbon residue. This process takes advantage of the energy value of pyrolysis gas, reduces the need for additional fuel, and improves the energy utilization efficiency and economy of the system. At the same time, by controlling the combustion conditions and strengthening the device maintenance, the stability of the fluidized bed combustion device is ensured and the impact on the environment is reduced, realizing the overall optimization of the pyrolysis system.

[0040] Further, in this embodiment, a star-type unloader or rotary valve is provided between the first pyrolysis reactor and the second pyrolysis reactor to ensure smooth transfer of materials.

[0041] In this embodiment, a discharge mechanism 11 is provided between the first pyrolysis reactor 4 and the second pyrolysis reactor 14, which includes a star-type unloader or rotary valve to ensure smooth transfer of materials from one reactor to another. This design allows the material that has completed the initial pyrolysis in the first pyrolysis reactor to enter the second pyrolysis reactor in an orderly and uninterrupted manner for further pyrolysis processing, thereby improving the processing capacity and continuity of the entire system. The star-type unloader or rotary valve, through its unique structure, not only effectively isolates oxygen from entering and maintains an oxygen-free environment in the system, but also precisely controls the flow of materials, avoiding the accumulation or blockage of materials during the transfer process. The implementation of this transition mechanism not only optimizes the pyrolysis efficiency and product quality of the materials, but also enhances the stability and safety of the system, achieving a more efficient and environmentally friendly pyrolysis process.

[0042] Further, in this embodiment, the rotational speed of the screw propeller and the temperature distribution of the heating cavity are precisely controlled to adjust the residence time of the materials at different temperature stages.

[0043] In this embodiment, the rotation speed of the screw propeller and the temperature distribution of the heating cavity are regulated to accurately control the residence time of the material in different temperature zones. Based on the deep understanding of the pyrolysis process of the material, the material will undergo a gradual pyrolysis process from low temperature to high temperature after entering the heating cavity. The adjustment of the rotation speed of the screw propeller can ensure that the material is fully preheated and starts to decompose in the low temperature section, and then smoothly transitions to the high temperature section to complete the complete cracking reaction and generate high-quality pyrolysis oil and pyrolysis gas. The optimization of the temperature distribution combined with the control of the rotation speed makes the movement of the material in the heating cavity synchronized with the pyrolysis reaction, avoiding local overheating or incomplete reaction, and improving the pyrolysis efficiency and product yield. The implementation effect shows that the material pyrolysis under this scheme is more uniform, the carbon residue generation is significantly reduced, and the consumption of pyrolysis gas is also reduced, improving the energy self-sufficiency of the system.

[0044] The application provides a waste rubber and plastic chemical recycling system, comprising: A waste rubber and plastic pyrolysis production line, which is the waste rubber and plastic pyrolysis production line described above; A recycling structure, which comprises a product storage unit, a product reuse unit and an energy recycling unit. The product storage unit is connected to the subsequent processing unit of the waste rubber and plastic pyrolysis production line and is used to store pyrolysis oil and pyrolysis gas. The product reuse unit is connected to the product storage unit and is used to convert the pyrolysis oil and pyrolysis gas into usable products. The energy recycling unit is connected to the product storage unit and the pyrolysis reaction structure and is used to use part of the pyrolysis gas as supplementary fuel for the combustion device to provide the heat required by the pyrolysis reaction structure.

[0045] In this embodiment, a waste rubber and plastic chemical recycling system is conceived to improve the energy efficiency and economy of the waste rubber and plastic pyrolysis process. The system integrates a waste rubber and plastic pyrolysis production line and a recycling structure, where the pyrolysis production line is responsible for cracking waste rubber and plastic into pyrolysis oil, pyrolysis gas and carbon residue under high temperature and anaerobic conditions. The recycling structure includes a product storage unit, a product reuse unit and an energy recycling unit, the product storage unit receives and stores pyrolysis oil and pyrolysis gas, the product reuse unit further converts these products into high value-added commodities, and the energy recycling unit ingeniously uses part of the pyrolysis gas as a supplementary fuel for the fluidized bed combustion device to burn with the carbon residue, thereby generating high temperature flue gas to provide heat for the pyrolysis reaction. By re-introducing the combustion heat of carbon residue and pyrolysis gas into the pyrolysis process, the system realizes internal recycling of energy, significantly reducing the dependence on external energy. In addition, the light hydrocarbon components in the pyrolysis gas are used as efficient fuel, which is uniformly mixed with the carbon residue in the fluidized bed for combustion, ensuring the stability of the combustion process and efficient use of pyrolysis gas. The system realizes high conversion rate of carbon residue and full combustion of pyrolysis gas by precisely controlling the combustion temperature and air / fuel ratio, combined with good gas-solid contact conditions in the fluidized bed, reducing solid residue and improving the overall energy efficiency of the pyrolysis system. Overall, the design of the system not only solves the problem of carbon residue disposal in the waste rubber and plastic pyrolysis process, but also enhances energy closed loop through the reuse of pyrolysis gas, reduces environmental pollution, improves economic benefits, and provides an efficient and green solution for waste rubber and plastic resource utilization.

[0046] In this embodiment, the primary pyrolysis reactor 4 and the secondary pyrolysis reactor 14 are closely coupled in structure and function through the discharge mechanism 11 and the flue gas passage 12, effectively promoting the smooth transition of materials and flue gas. The material discharge mechanism 11 adopts a star-shaped discharger design, ensuring the orderly transfer of materials from the primary pyrolysis reactor to the secondary pyrolysis reactor, while maintaining an anaerobic environment between the two reactors, avoiding the mixing of oxygen. The design of the flue gas passage 12 ensures efficient and leak-free transmission of flue gas between the two reactors, improving heat energy utilization efficiency through flue gas circulation. In the entire transition mechanism, the transmission of materials and flue gas is achieved through the synchronous control of drive motor one 10 and drive motor two 13, ensuring the continuity of material movement in the reactor and the stability of flue gas circulation, thereby improving the efficiency of the pyrolysis process and the quality of the products. In addition, the sealing and heat insulation design of the flue gas passage 12, as well as the precise control of the material discharge mechanism 11, together ensure the stability and safety of the system in long-term operation, reducing maintenance costs and improving economic efficiency.

[0047] The actual application design of the waste rubber and plastic pyrolysis system of the present application is as follows: Figure 1The pyrolysis system is composed of a feeding unit, a heat supply unit, a pyrolysis unit and a condensation and purification unit. The waste rubber and plastic is transported by the feeding unit to the pyrolysis unit to generate pyrolysis gas and carbon residue under high-temperature and anaerobic environment, the pyrolysis gas is generated into pyrolysis oil and pyrolysis gas through the condensation and purification unit, and the carbon residue and part of the pyrolysis gas enter the fluidized bed combustion device to generate high-temperature flue gas to provide heat for the pyrolysis unit.

[0048] The feeding unit is composed of a feeding bin 1, a screw feeder 2 and a nitrogen inlet 3. The pyrolysis unit adopts a two-stage pyrolysis reactor composed of a first-stage pyrolysis reactor 4 and a second-stage pyrolysis reactor 14. The first-stage pyrolysis reactor 4 is composed of an outer cylinder 6, an inner cylinder 7, a spiral blade 8, a rotating shaft 9 and a driving motor 10. The second-stage pyrolysis reactor 14 is composed of a driving motor 13, an outer cylinder 15, an inner cylinder 16, a rotating shaft 17 and a spiral blade 18. The left upper side of the first-stage pyrolysis reactor 4 is provided with a flue gas outlet 5. The material unloading mechanism 11 and the flue gas passage 12 are arranged between the first-stage pyrolysis reactor 4 and the second-stage pyrolysis reactor 14. The left lower side of the second-stage pyrolysis reactor 14 is provided with a fluidized bed 25. The left lower side of the inner cylinder 16 is provided with a slag outlet 19. The left side of the inner cylinder 16 is provided with a pyrolysis gas outlet 21. The lower side of the slag outlet 19 is provided with a first material return device 20 connected with the bottom of the fluidized bed. The condensation and purification unit includes a cyclone dust collector 22 and a condensation tower 24. The pyrolysis gas outlet 21 is connected with the cyclone dust collector 22. The lower side of the cyclone dust collector 22 is provided with a second material return device 23 connected with the bottom of the fluidized bed. The outlet of the cyclone dust collector 22 is connected with the condensation tower 24. The heat supply unit is provided with a fluidized bed. The crushed waste rubber and plastic is put into the feeding bin 1. The broken particle size of the waste rubber and plastic is less than 10 mm. The waste rubber and plastic enters the first-stage pyrolysis reactor 4 through the screw feeder 2. The screw feeder is a gradually variable pitch screw feeder. The plastic is compacted in the conveying process. The nitrogen inlet 3 is arranged on the feeding pipeline. Nitrogen is introduced before starting to ensure that the waste rubber and plastic is pyrolyzed in an anaerobic environment.

[0049] The outer cylinder 6 of the first-stage pyrolysis reactor 4 is stationary. The rotating shaft 9 drives the inner cylinder 7 to rotate by the driving motor 10. The rotating shaft 9 penetrates the inner cylinder 7. One end of the rotating shaft 9 is connected with the inner cylinder 7 through a sleeve with sealing function. The other end of the rotating shaft 9 penetrates the end cover of the inner cylinder 7 through a sealing structure. The inner cylinder 7 and the outer cylinder 6 are connected through dynamic sealing. A hot air cavity is formed between the inner cylinder 7 and the outer cylinder 6. The outer cylinder 6 is made of refractory bricks and covered with heat preservation materials for heat preservation. The pyrolysis time is controlled by controlling the rotating speed of the rotating shaft 9. The spiral blade 8 is fixed on the rotating shaft 9 to form a material conveying guide groove in the inner cylinder 7. The waste rubber and plastic is conveyed from the left end to the right end by the rotation of the inner cylinder 7 and is reasonably distributed in the inner cylinder 7 to realize the full pyrolysis of the waste rubber and plastic. At the same time, the spiral blade 8 can also remove the coking substances on the inner wall of the inner cylinder 7 to avoid the problems of low heat conduction efficiency and blockage caused by the accumulation of coking substances.

[0050] The operation mode of the secondary pyrolysis reactor 14 is the same as the primary pyrolysis reactor 4. The helical pitch of the helical blade one 8 and the helical blade two 18 is greater than the size of the waste rubber and plastic particles, and the gap between the helical blade one 8 and the bottom of the inner cylinder one 7 and the gap between the helical blade two 18 and the bottom of the inner cylinder two 16 is between 4-8mm at the operating temperature, which ensures smooth rotation and timely cleaning of the wall coking.

[0051] The temperature of the inner cylinder one 7 in the primary pyrolysis reactor 4 is controlled at 350℃-450℃, and the waste rubber and plastic is moved from the feed inlet to the material unloading mechanism 11 at the right end under the push of the helical blade one 8. As the viscosity of the waste rubber and plastic continuously increases due to continuous pyrolysis and gasification, the waste rubber and plastic that has not been completely decomposed is conveyed to the secondary pyrolysis reactor 14 through the material unloading mechanism 11 by the helical push for further heat decomposition. The temperature of the inner cylinder two 16 in the secondary pyrolysis reactor 14 is controlled at 450℃-550℃. The pyrolysis gas generated by pyrolysis is discharged from the pyrolysis gas outlet 21 on the left side of the secondary pyrolysis reactor 14. The carbon residue generated by pyrolysis falls into the material return device one 20 from the slag outlet 19 at the lower end of the secondary pyrolysis reactor 14 and is sent into the fluidized bed.

[0052] The two-stage pyrolysis reactor increases the travel distance of the waste rubber and plastic in the pyrolysis reactor, increases the heating area, and at the same time, the waste rubber and plastic is moved by the rotation and push of the helical blade, so that the waste rubber and plastic is evenly heated in the inner cylinder, avoiding uneven heating. The two-stage pyrolysis reactor controls different reaction temperatures and controls the residence time of the material by different rotating speeds, so as to more accurately control the reaction process and improve the yield and quality of the pyrolysis oil and pyrolysis gas.

[0053] The pyrolysis gas enters the cyclone dust collector 22 to collect the carbon residue in the pyrolysis gas and is sent back to the fluidized bed through the material return device two 23. The pyrolysis gas coming out of the cyclone dust collector 22 enters the condensation tower to separate and obtain the product pyrolysis oil and pyrolysis gas. Part of the pyrolysis gas is transported to the fluidized bed combustion device as supplementary fuel.

[0054] The high-temperature flue gas generated by the combustion of carbon residue and pyrolysis gas in the fluidized bed is introduced into the pyrolysis cavity of the secondary pyrolysis reactor 14. The high-temperature flue gas enters the primary pyrolysis reactor 4 through the flue gas passage 12, and the high-temperature flue gas is distributed around the inner cylinder of the pyrolysis reactor, so as to uniformly heat the inner cylinder. The flow direction of the high-temperature flue gas is opposite to the flow direction of the waste rubber and plastic, which ensures that the waste rubber and plastic is fully pyrolyzed in the pyrolysis reactor. The pyrolysis gas outlet 5 is arranged at the upper left of the primary pyrolysis reactor 4, part of the pyrolysis gas is sent back to the fluidized bed, and the rest is discharged into the atmosphere after flue gas purification.

[0055] The carbon residue transported by the first return feeder 20 and the second return feeder 23 to the fluidized bed serves as the main fuel of the heat supply unit, and the insufficient heat is supplemented by the pyrolysis gas, and part of the high-temperature flue gas enters the fluidized bed for circulation and back burning, the oxygen content of the flue gas is low, the emission of nitrogen oxides is reduced, and the temperature of the flue gas entering the pyrolysis reactor from the outlet of the fluidized bed combustion device is controlled between 700-800℃. The medium transported by the first return feeder 20 and the second return feeder 23 is nitrogen.

[0056] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A waste rubber and plastic pyrolysis system, characterized by, The system comprises: a feeding unit, which comprises a feeding bin, a material conveying mechanism and an anaerobic protection mechanism, the material conveying mechanism being used to convey waste rubber and plastic materials from the feeding bin to a pyrolysis reaction unit in an anaerobic environment provided by the anaerobic protection mechanism; a pyrolysis reaction unit, which comprises a primary pyrolysis reactor and a secondary pyrolysis reactor, each of the pyrolysis reactors comprising at least one heating cavity, a material conveying mechanism and a heating source, the heating cavity providing a closed environment under the action of the heating source, the material conveying mechanism advancing the material in a predetermined direction within the heating cavity, the outlet of the primary pyrolysis reactor being in communication with the inlet of the secondary pyrolysis reactor, so that the material sequentially passes through the primary pyrolysis reactor and the secondary pyrolysis reactor for multi-stage pyrolysis; a product recovery unit, which comprises a pyrolysis gas purification and condensation unit, the pyrolysis gas purification and condensation unit being connected to the secondary pyrolysis reactor for receiving and purifying the pyrolysis gas generated by the secondary pyrolysis reactor, and simultaneously condensing the pyrolysis gas into pyrolysis oil, the purification process further comprising separating carbon residue particles, wherein the separation of the carbon residue particles is achieved based on the movement trajectory of the pyrolysis gas within the purification unit.

2. The waste rubber and plastic pyrolysis system of claim 1, wherein, The material conveying mechanism is a progressive variable-pitch screw feeder, the pitch of the screw feeder gradually decreasing along the material conveying direction.

3. The waste rubber and plastic pyrolysis system of claim 1, wherein, The primary pyrolysis reactor is internally provided with screw blades one, which advance the material within the heating cavity; the secondary pyrolysis reactor is internally provided with screw blades two, which advance the material within the heating cavity; the screw blades one and the screw blades two are precisely controlled in the gap with the bottom of the heating cavity to remove the internal wall coking.

4. The waste rubber and plastic pyrolysis system of claim 1, wherein, A discharging mechanism is provided between the primary pyrolysis reactor and the secondary pyrolysis reactor to ensure smooth transfer of the material.

5. The waste rubber and plastic pyrolysis system of claim 1, wherein, The pyrolysis gas purification and condensation unit further recovers part of the pyrolysis gas as supplemental fuel.

6. The waste rubber and plastic pyrolysis system of claim 2, wherein, The rotation speed of the screw feeder and the temperature distribution of the heating cavity are precisely controlled to adjust the residence time of the material at different temperature stages.

7. A production line for pyrolysis of waste rubber and plastic, characterized in that, The system comprises: a waste rubber and plastic pyrolysis system, which is the waste rubber and plastic pyrolysis system according to any one of claims 1-6; a production line body, which comprises a crushing unit, a pretreatment unit, the waste rubber and plastic pyrolysis system and a subsequent treatment unit, the crushing unit being connected to the pretreatment unit, the pretreatment unit being connected to the feeding unit, and the subsequent treatment unit being connected to the product recovery unit.

8. A waste rubber and plastic pyrolysis system application, characterized by, The system comprises: a waste rubber and plastic pyrolysis production line, which is the waste rubber and plastic pyrolysis production line according to claim 7; The recycling structure comprises a product storage unit, a product recycling unit and an energy recycling unit, the product storage unit is connected with a subsequent processing unit of the waste rubber and plastic pyrolysis production line, and is used for storing pyrolysis oil and pyrolysis gas; the product recycling unit is connected with the product storage unit, and is used for converting the pyrolysis oil and pyrolysis gas into available products; the energy recycling unit is connected with the product storage unit and a pyrolysis reaction structure, and is used for taking part of the pyrolysis gas as a supplementary fuel of a combustion device to provide heat required by the pyrolysis reaction structure.

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