Method and system for reclaiming devulcanized rubber

Abstract

The present application relates to the technical field of rubber regeneration, and specifically provides a rubber devulcanization recovery method and system, which at least solves one of the problems of poor devulcanization selectivity, large quality fluctuation of reclaimed rubber and difficulty in effectively controlling harmful by-products caused by inconsistent initial state of raw materials in the existing devulcanization process. The rubber devulcanization recovery method comprises: preheating and dehumidifying the raw materials; crushing the raw materials, and introducing a supercritical fluid into the crushed raw materials, and then applying shear mixing to realize devulcanization reaction; and extruding the reacted materials to obtain rubber products. By adding preheating and dehumidifying treatment of the raw materials before the reaction, the problem of unstable process caused by fluctuation of the initial state of the raw materials in the existing devulcanization process is effectively overcome, which is beneficial to improving the quality stability and physical property retention rate of the reclaimed rubber.

Description

Technical Field

[0001] This invention relates to the field of rubber regeneration technology, specifically providing a method and system for rubber desulfurization and recovery. Background Technology

[0002] With the continuous increase in car ownership and the accelerated pace of vehicle replacement, large quantities of waste rubber (especially waste tires) are accumulating. This not only occupies valuable land resources but also easily breeds mosquitoes and insects, causes fires, and releases toxic leachate and harmful gases during long-term open-air storage, posing a serious threat to the soil, water bodies, and atmospheric environment. Meanwhile, rubber is an important strategic material and industrial raw material; if the natural and synthetic rubber components abundant in waste tires are not fully recycled, it will result in enormous resource waste. Therefore, restoring the processability of waste rubber and putting it back into the material cycle through desulfurization and regeneration is not only a practical need to alleviate environmental pressure but also an important path to achieving the green and sustainable development of the rubber industry.

[0003] However, existing desulfurization processes are generally constrained by the uncertainty of the initial state of raw materials, which is one of the key factors restricting process stability and product quality. Raw materials (such as rubber powder) often enter the reaction unit under uncontrolled temperature and humidity conditions, and their physical state fluctuates with seasonal changes, storage conditions, and pretreatment processes, resulting in a lack of consistency in the initial process conditions. In addition, rubber powder itself has an extremely low thermal conductivity, and heat transfer within the material is extremely slow, further exacerbating the non-uniform temperature distribution along the reaction system and across its cross-section. This non-uniform temperature field easily forms localized overheated regions, whose peak temperatures often exceed the ideal desulfurization temperature window. This causes the desulfurization reaction to deviate from the expected path of selectively breaking sulfur crosslinking bonds, instead inducing irreversible breakage of the carbon-carbon backbone, ultimately resulting in drastic fluctuations in the quality of reclaimed rubber and low retention of physical properties.

[0004] Furthermore, localized overheating can generate a large number of harmful byproducts, such as sulfur-containing vapors, volatile organic compounds, fumes, and heavy condensable components released during high-temperature desulfurization. If these byproducts lack effective graded collection and treatment measures, they will lead to a series of problems, including equipment scaling, increased maintenance burden, excessive pollutant emissions, and threats to the health of operators. Summary of the Invention

[0005] The present invention aims to solve the above-mentioned technical problems, namely, to solve at least one of the problems in the existing desulfurization process, namely, poor desulfurization selectivity, large fluctuations in the quality of reclaimed rubber, and difficulty in effectively controlling harmful by-products due to inconsistent initial states of raw materials.

[0006] In a first aspect, the present invention provides a rubber desulfurization and recovery method, the rubber desulfurization and recovery method comprising: preheating and dehumidifying the raw material; crushing the raw material and introducing a supercritical fluid into the crushed raw material, and then applying shear mixing to achieve a desulfurization reaction; and extruding the reacted material to obtain a rubber product.

[0007] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery method, the "preheating and dehumidification treatment of raw materials" includes: preheating and dehumidifying the raw materials to bring them to a preset temperature and a preset humidity and maintain them for a preset time; wherein the preset temperature is 110℃~130℃, the preset humidity is less than or equal to 0.1%, and the preset time is 3 minutes to 8 minutes.

[0008] In some feasible implementations of the above-mentioned rubber desulfurization and recovery method, the "introduction of supercritical fluid into the crushed raw material" includes: introducing supercritical fluid into the crushed raw material at a preset ratio; wherein the injection volume of supercritical fluid is 2wt% to 3wt% of the material throughput.

[0009] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery method, the rubber desulfurization and recovery method further includes: collecting the reaction tail gas while obtaining the rubber product, and purifying the reaction tail gas.

[0010] In some feasible implementations of the above-mentioned rubber desulfurization and recovery method, the "purification treatment of the reaction tail gas" includes: purifying the reaction tail gas step by step through condensation, washing, and filtration to achieve the separation and extraction of pollutants.

[0011] In a second aspect, the present invention also provides a rubber desulfurization and recovery system, the rubber desulfurization and recovery system including a processor, the processor being used to execute the rubber desulfurization and recovery method described in any of the foregoing technical solutions.

[0012] In some feasible embodiments of the aforementioned rubber desulfurization and recovery system, the system includes: a pretreatment device for preheating and dehumidifying the raw material; and a twin-screw extruder comprising, along the material flow direction, a kneading and sealing zone, a supercritical fluid injection zone, and a kneading reaction zone; wherein the kneading and sealing zone is at least used for kneading and crushing the raw material and forming a high-pressure zone to achieve dynamic sealing of the melt, and the kneading reaction zone is at least used for shearing and mixing the material to promote the desulfurization reaction; the rubber desulfurization and recovery method includes: feeding the raw material into the pretreatment device for preheating and dehumidification; feeding the raw material into the twin-screw extruder and injecting supercritical fluid into the supercritical fluid injection zone; causing the raw material to be crushed at the front end of the kneading and sealing zone, merged with the supercritical fluid in the supercritical fluid injection zone under the high-pressure melt sealing action at the rear end of the kneading and sealing zone, and sheared and mixed in the kneading reaction zone to achieve the desulfurization reaction; and extruding the reacted material through the twin-screw extruder to obtain a rubber product.

[0013] In some feasible embodiments of the aforementioned rubber desulfurization and recovery system, the pretreatment device includes an infrared spiral drying and heating drum; and / or, the kneading and sealing zone is also used to heat the raw materials and increase the pressure; and / or, the twin-screw extruder also includes a raw material conveying zone located upstream of the kneading and sealing zone; and / or, the twin-screw extruder also includes a stable output zone located downstream of the kneading reaction zone.

[0014] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery system, the twin-screw extruder includes a pair of screws meshing in the same direction. The screws are provided with forward thread sections in both the kneading and sealing zone and the supercritical fluid injection zone. The screws are also provided with reverse thread sections between the kneading and sealing zone and the supercritical fluid injection zone, so as to form a reverse seal between the two zones through the reverse thread sections.

[0015] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery system, the screw is provided with multiple kneading discs in the kneading reaction zone; and / or, the twin-screw extruder has a body and an extrusion die, the screw being disposed in the body and the extrusion die being disposed at the downstream end of the body.

[0016] In some feasible embodiments of the rubber desulfurization and recovery system described above, the rubber desulfurization and recovery system further includes a gas treatment device, which is connected to the twin-screw extruder via a pipeline to treat the reaction tail gas.

[0017] In some feasible embodiments of the rubber desulfurization and recovery system described above, the gas treatment device includes a condenser, a scrubbing tower, and an activated carbon filter connected in sequence.

[0018] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery system, the condenser tank forms a first cavity, the condenser tank is provided with a first air inlet and a first air outlet communicating with the first cavity, the first cavity is provided with a condenser pipe, the condenser pipe is provided with a cooling water inlet and a cooling water outlet, and the first air inlet is connected to the twin-screw extruder; the washing tower forms a second cavity, the washing tower is provided with a second air inlet, a second air outlet and a washing liquid inlet communicating with the second cavity, the second air inlet is connected to the first air outlet; the activated carbon filter forms a third cavity, the third cavity is provided with an activated carbon adsorption layer, the activated carbon filter is provided with a third air inlet and a third air outlet communicating with the third cavity, the third air inlet is connected to the second air outlet.

[0019] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery system, the condenser tube is a spiral coil; and / or, the liquid flow direction in the condenser tube is from bottom to top; and / or, the condenser tank is also provided with a condensate outlet communicating with the first cavity.

[0020] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery system, the washing tower is provided with a packing layer, and the packing layer has gaps; wherein, the second air inlet is located below the packing layer, and the second air outlet is located above the packing layer; and / or, the washing tower is provided with a plurality of nozzles communicating with the washing liquid inlet, and the nozzles are located above the packing layer.

[0021] In some feasible embodiments of the above-mentioned rubber desulfurization and recovery system, the third cavity is provided with an annular gas collecting chamber and a core gas collecting pipe. The annular gas collecting chamber is arranged around the periphery of the activated carbon adsorption layer, and the core gas collecting pipe passes through the activated carbon adsorption layer. The annular gas collecting chamber is provided with a first vent, and the core gas collecting pipe is provided with a second vent. The first vent is connected to the second vent through the activated carbon adsorption layer. The third air inlet is connected to the top of the annular gas collecting chamber, and the third air outlet is connected to the top of the core gas collecting pipe.

[0022] In some feasible embodiments of the rubber desulfurization and recovery system described above, the supercritical fluid is supercritical carbon dioxide; and / or, the rubber desulfurization and recovery system further includes a supercritical fluid injection device, which is connected to the supercritical fluid injection zone via a pipeline.

[0023] The beneficial effects of this invention are: (1) This invention effectively overcomes the instability problem caused by fluctuations in the initial state of raw materials in existing desulfurization processes by adding preheating and dehumidification treatment of raw materials before the reaction. Among them, preheating raises the overall temperature of the material evenly, while dehumidification eliminates moisture interference. The synergistic effect of the two improves the uneven internal heat transfer caused by the low thermal conductivity of rubber powder, making the temperature distribution of the reaction system more uniform and effectively suppressing local overheating areas. This improvement is conducive to promoting the selective breaking of sulfur crosslinking bonds in the desulfurization reaction within the ideal temperature window, while reducing the irreversible breaking of carbon-carbon backbone, thereby improving the quality stability and property retention rate of reclaimed rubber.

[0024] (2) Simultaneously, the present invention introduces supercritical fluid into the crushed raw materials and applies shear mixing at the same time, so that the desulfurization reaction is completed in a supercritical environment. With its excellent penetration and swelling capacity, supercritical fluid fully softens the rubber crosslinking network and forms a synergistic effect with shear force, making the crosslinking bonds easier to break under the swelling and stretching state, which helps to further improve the quality stability and property retention rate of reclaimed rubber.

[0025] (3) Furthermore, thanks to the preheating and dehumidification that ensures the uniformity of the reaction temperature field, and the synergistic effect of supercritical fluid and shear in effectively controlling the risk of viscous heat generation and local overheating, the peak temperature of the entire desulfurization process is effectively limited within an ideal window. This helps reduce harmful byproducts such as sulfur-containing vapors, volatile organic compounds, smoke, and heavy condensable components generated at high temperatures. This not only effectively reduces the burden of tail gas treatment and avoids equipment scaling and excessive pollutant emissions, but also provides a safer working environment for operators, thus balancing environmental protection and safety. Attached Figure Description

[0026] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which: Figure 1 A schematic diagram of the process flow of the rubber desulfurization and recovery method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the operation process between various devices in the rubber desulfurization and recovery system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the internal structure of the twin-screw extruder in the rubber desulfurization and recovery system provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the gas treatment device of the rubber desulfurization and recovery system provided in an embodiment of the present invention; Figure 5 Gas flow diagram of activated carbon filter in rubber desulfurization and recovery system provided in this embodiment of the invention; Figure 6 This is a schematic diagram of the pretreatment device of the rubber desulfurization and recovery system provided in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Pre-treatment unit; 2. Twin-screw extruder; 21. Raw material conveying zone; 22. Kneading and sealing zone; 23. Supercritical fluid injection zone; 24. Kneading reaction zone; 25. Stable output zone; 26. Screw; 261. Forward thread section; 262. Reverse thread section; 263. Kneading disc; 3. Gas treatment unit; 31. Condenser; 311. First air inlet; 312. First air outlet; 313. Condensate outlet; 314. Condenser pipe; 315. Cooling water inlet; 316. Cooling water outlet; 32. 321. Scrubber; 322. Second air inlet; 323. Second air outlet; 324. Scrubber liquid inlet; 325. First drain outlet; 326. Packing layer; 327. Nozzle; 328. Circulation pump; 339. Activated carbon filter; 331. Third air inlet; 332. Third air outlet; 333. Activated carbon adsorption layer; 334. Annular gas collection chamber; 335. Core gas collection pipe; 336. Second drain outlet; 337. Horizontal exhaust pipe; 34. Short connecting pipe; 35. Long connecting pipe; 4. Supercritical fluid injection device. Detailed Implementation

[0028] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific applications. Numerous specific details are set forth in the following detailed description to better illustrate the present invention. Those skilled in the art should understand that the present invention can be practiced even without certain specific details.

[0029] In the description of this invention, terms such as "upper," "lower," "inner," "outer," "left," "right," "front," and "rear," which indicate direction or positional relationships, are based on actual application and are used merely for ease of description. They do not indicate or imply that the device to be protected must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, ordinal numbers such as "first" and "second" are used only for convenience and are not intended to indicate or imply relative importance.

[0030] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Please see Figure 1 This invention provides a method for desulfurizing and recovering rubber, the method comprising: S1. Preheat and dehumidify the raw materials.

[0032] Before the desulfurization reaction, the raw materials are preheated and dehumidified to ensure that the rubber powder reaches a uniform and stable temperature and moisture content before participating in the reaction. This effectively eliminates the fluctuations in the state of the raw materials caused by seasonal changes, storage conditions and differences in pretreatment processes, and provides a stable and controllable process starting point for the subsequent desulfurization reaction.

[0033] Specifically, the raw materials are preheated and dehumidified to reach a preset temperature and humidity and maintain this temperature and humidity for a preset duration. The preset temperature is 110℃–130℃, the preset humidity is ≤0.1%, and the preset duration is 3–8 minutes. For example, the preset temperature is 120℃, the preset humidity is 0.1%, and the preset duration is 5 minutes. By clearly defining these three process parameters (temperature, humidity, and time), the pretreatment state of the raw materials is controlled, ensuring that the rubber powder participating in the desulfurization reaction has uniform and stable physical properties. This eliminates raw material fluctuations caused by seasonality, storage, and pretreatment differences, providing repeatable initial conditions for subsequent desulfurization reactions. Furthermore, it helps ensure that different batches of raw materials participating in the desulfurization reaction have essentially the same initial state, thereby greatly improving process repeatability and product stability. Simultaneously, maintaining the preset duration ensures sufficient heat and moisture transfer and balance within the rubber powder, making the pretreatment more thorough. This lays a reliable foundation for the stability of the entire desulfurization process and the consistency of the quality of the reclaimed rubber products.

[0034] S2. The raw materials are crushed and then supercritical fluid is introduced into the crushed raw materials, followed by shearing and mixing to achieve the desulfurization reaction.

[0035] By crushing the raw materials, the specific surface area of ​​the materials is increased, providing sufficient penetration channels and contact interfaces for the supercritical fluid. On the other hand, it ensures that the materials are subjected to uniform stress during the subsequent shearing and mixing process, avoiding shear dead zones and local stress concentrations. On this basis, the supercritical fluid is introduced, and its excellent penetration and swelling capabilities are used to fully soften the rubber cross-linking network, so that the sulfur cross-linking bonds are in an activated and tensile state. When shearing and mixing is then applied, the selective breaking of sulfur cross-linking bonds can be achieved with lower energy input, and the risk of carbon-carbon backbone breakage can be effectively reduced.

[0036] Specifically, supercritical fluid is introduced into the crushed raw material at a preset ratio, wherein the injection volume of supercritical fluid is 2wt% to 3wt% of the material throughput. By controlling the feed ratio, the injection volume of supercritical fluid can be flexibly adjusted according to actual process requirements to ensure that it achieves appropriate swelling and penetration depth in the rubber matrix, avoiding insufficient desulfurization or over-plasticization due to improper ratio.

[0037] S3. The reacted material is extruded and molded to obtain a rubber product.

[0038] The rubber melt that has completed the desulfurization reaction is extruded through an extrusion die to obtain a continuous strip or sheet rubber product with a specific cross-sectional shape, which facilitates the connection of subsequent cooling, cutting and processing and packaging processes.

[0039] Furthermore, after step S3, the rubber desulfurization and recovery method further includes: S4. Collect the reaction tail gas while obtaining the rubber product, and purify the reaction tail gas.

[0040] While obtaining rubber products, the reaction exhaust gas is collected and purified. The harmful components are effectively removed or transformed, so that the emitted gas meets environmental protection standards. This effectively prevents harmful byproducts such as sulfur-containing vapors, volatile organic compounds, smoke and heavy condensable components generated during high-temperature desulfurization from being directly discharged into the atmosphere. It controls the spread of pollutants from the source and effectively reduces the negative impact on the surrounding environment.

[0041] Specifically, the reaction tail gas is purified step by step through condensation, washing, and filtration to achieve the separation and extraction of pollutants.

[0042] The reaction exhaust gas is purified step-by-step through condensation, washing, and filtration, forming a tiered treatment process of "staged condensation—chemical absorption—deep adsorption," which can classify and remove pollutants with different physicochemical properties in the exhaust gas. Specifically, condensation can liquefy and separate heavy condensable oils and hydrocarbon components in the high-temperature exhaust gas, recovering valuable resources and preventing them from condensing and clogging in subsequent equipment; washing further removes acidic gases, aerosols, and fine particulate matter through gas-liquid countercurrent contact; and filtration performs final adsorption and retention of residual volatile organic compounds and trace pollutants.

[0043] This invention effectively overcomes the instability caused by fluctuations in the initial state of raw materials in existing desulfurization processes by adding preheating and dehumidification treatments to the raw materials before the reaction. Preheating ensures a uniform increase in the overall temperature of the material, while dehumidification eliminates moisture interference. The synergistic effect of these two processes improves the uneven internal heat transfer caused by the low thermal conductivity of rubber powder, resulting in a more uniform temperature distribution in the reaction system and effectively suppressing localized overheating. This improvement facilitates the selective breaking of sulfur crosslinking bonds within an ideal temperature window during the desulfurization reaction, while reducing irreversible breakage of the carbon-carbon backbone, thereby improving the quality stability and property retention rate of the reclaimed rubber.

[0044] Simultaneously, supercritical fluid is introduced into the crushed raw materials, and shear mixing is applied concurrently, allowing the desulfurization reaction to complete in a supercritical environment. The supercritical fluid, with its excellent penetration and swelling capabilities, fully softens the rubber cross-linking network, creating a synergistic effect with shear force. This makes the cross-links easier to break under swollen and stretched conditions, further improving the quality stability and property retention of the reclaimed rubber.

[0045] Furthermore, thanks to the preheating and dehumidification that ensures a uniform reaction temperature field, and the synergistic effect of supercritical fluid and shear to effectively control the risks of viscous heat generation and localized overheating, the peak temperature of the entire desulfurization process is effectively limited within an ideal window. This helps reduce harmful byproducts such as sulfur-containing vapors, volatile organic compounds, fumes, and heavy condensable components generated at high temperatures. This not only effectively reduces the burden of exhaust gas treatment and avoids equipment scaling and excessive pollutant emissions, but also provides a safer working environment for operators, thus balancing environmental protection and safety.

[0046] Based on the aforementioned rubber desulfurization and recovery methods, such as Figures 2 to 6 As shown, the present invention also provides a rubber desulfurization and recovery system adapted to the aforementioned rubber desulfurization and recovery method. The rubber desulfurization and recovery system includes a processor, which is used to execute the rubber desulfurization and recovery method in any of the aforementioned technical solutions.

[0047] In addition, the rubber desulfurization and recovery system also includes a memory adapted to store multiple program codes, which are adapted to be loaded by a processor and executed as the rubber desulfurization and recovery method in any of the aforementioned technical solutions.

[0048] In a preferred embodiment, the rubber desulfurization and recovery system includes a pretreatment unit 1 and a twin-screw extruder 2.

[0049] The pretreatment unit 1 is used at least to preheat and dehumidify the raw materials to achieve thermal equilibrium and reduce moisture content, thereby adjusting the raw materials to a uniform and stable state before they enter the core reaction zone. By uniformly preheating and dehumidifying the raw materials, fluctuations in temperature and moisture content caused by seasonal changes and differences in storage conditions can be mitigated, laying the foundation for a stable desulfurization reaction in the future.

[0050] Furthermore, such as Figure 6 As shown, the pretreatment device 1 includes an infrared spiral drying and heating drum. This drum continuously lifts, tumbles, and throws the rubber powder through the heating zone, achieving dynamic heating of the material rather than static radiant heating. Compared to traditional heating methods, infrared heating has the advantages of strong penetration, uniform heating, and high efficiency. Combined with the spiral drum structure, the material continuously tumbles during its forward movement, receiving all-around radiant heating and avoiding localized overheating. For example, the drum heats the raw material to approximately 120°C and maintains this temperature for about 5 minutes. Simultaneously, the drum is equipped with a dehumidification function to effectively mitigate the impact of seasonal moisture fluctuations. This reduces the shear energy input required for subsequent processes in the twin-screw extruder 2, narrows the temperature distribution range of the feed, reduces material instability caused by moisture, and improves the consistency of the feed entering the core reaction zone. Figure 2 As indicated by arrow A, after the material leaves the drum, it is conveyed to the feeder of the twin-screw extruder 2 via a conveyor.

[0051] Based on the foregoing, step S1 specifically involves feeding the raw material into the pre-treatment device 1 for preheating and dehumidification. By preheating and dehumidifying the raw material in the pre-treatment device 1, the rubber powder reaches a uniform and stable temperature and moisture content state before entering the extruder. This effectively eliminates fluctuations in the raw material state caused by seasonal changes, storage conditions, and differences in pre-treatment processes, providing a stable and controllable starting point for the subsequent desulfurization reaction. Simultaneously, the preheating treatment allows the rubber powder to carry some heat energy into the extruder, reducing the burden of mechanical shearing and heat generation, narrowing the feed temperature distribution range, and reducing material instability caused by moisture, thereby improving the consistency of the feed state.

[0052] like Figure 3 As shown, the twin-screw extruder 2 includes, along the material flow direction, a kneading and sealing zone 22, a supercritical fluid injection zone 23, and a kneading reaction zone 24. This functional zoning design breaks down the complex desulfurization process into orderly and controllable segmented operations. Through the coordinated operation of each zone, effective control of the desulfurization reaction conditions is achieved.

[0053] The front end of the kneading and sealing zone 22 is used at least for kneading and crushing the raw materials. By initially kneading and crushing the pre-treated raw materials, the density of the material can be increased and the temperature can be raised, which prepares the material for subsequent reactions. At the same time, the front end of the kneading and sealing zone 22 is also used to heat the raw materials and increase the pressure, that is, it undertakes the functions of heating and pressurizing. It can serve as a buffer section for the transition from atmospheric pressure feed to high pressure reaction zone, creating conditions for the pressure building and sealing at the rear end of the kneading and sealing zone 22.

[0054] Simultaneously, the rear end of the kneading and sealing zone 22 is also used to form a high-pressure area to achieve dynamic sealing of the melt. By setting up a reverse conveying element to form a pressure barrier, a dynamic melt seal is formed on the material's forward path, effectively preventing the subsequently injected supercritical fluid from flowing upstream and ensuring that the supercritical fluid is confined within the preset reaction area.

[0055] The supercritical fluid injection zone 23 is used to inject supercritical fluid into the twin-screw extruder 2, allowing the supercritical fluid to fully penetrate into the rubber crosslinking network. Due to its excellent flowability and swelling capacity, the supercritical fluid can effectively reduce the crosslinking density of the rubber and weaken the intermolecular forces, providing a favorable microenvironment for subsequent selective cleavage of sulfur bonds. Simultaneously, the excellent mass and heat transfer characteristics of the supercritical fluid help improve the temperature uniformity within the reaction system and promote the timely removal of low-molecular-weight decomposition products.

[0056] The kneading reaction zone 24 is the core area of ​​the desulfurization reaction, used at least for shearing and mixing the materials to promote the desulfurization reaction, ensuring full contact between the materials and the supercritical fluid, promoting the selective breaking of sulfur crosslinking bonds, and avoiding excessive degradation of the main chain by reasonably controlling the shear intensity. Through the synergistic cooperation of the kneading sealing zone 22, the supercritical fluid injection zone 23, and the kneading reaction zone 24, the system can achieve a highly efficient and selective desulfurization reaction under mild conditions, effectively improving the product quality and batch consistency of the reclaimed rubber.

[0057] Based on the foregoing, step S2 includes steps S21 and S22, as follows: S21. Feed the raw material into the twin-screw extruder 2 and inject supercritical fluid into the supercritical fluid injection zone 23.

[0058] The preheated and dehumidified rubber powder is fed into a twin-screw extruder 2, and supercritical fluid (preferably supercritical carbon dioxide) is injected into the supercritical fluid injection zone 23. Utilizing the excellent flowability and permeability of the supercritical fluid, it fully wets and swells the rubber crosslinking network, weakening the intermolecular forces and creating a favorable microenvironment for subsequent selective cleavage of sulfur crosslinking bonds. Simultaneously, the excellent mass and heat transfer characteristics of the supercritical fluid help improve the temperature uniformity within the reaction system and promote the timely removal of low-molecular-weight decomposition products.

[0059] Specifically, the raw materials and supercritical fluid are fed separately into the twin-screw extruder 2 at a preset ratio. By precisely controlling the feed ratio, the injection volume of the supercritical fluid can be flexibly adjusted according to actual process requirements, ensuring that it achieves appropriate swelling and penetration depth in the rubber matrix, avoiding insufficient desulfurization or over-plasticization due to improper ratios. Simultaneously, the separate injection method ensures that the supercritical fluid is stably injected into the preset reaction zone under the sealing protection of the kneading and sealing zone 22, avoiding the risk of pressure fluctuations or fluid leakage caused by pre-mixing. This helps maintain the stability and repeatability of the supercritical environment within the reaction system, thus providing controllable media conditions for subsequent selective desulfurization reactions and ensuring consistent desulfurization effects.

[0060] For example, the injection amount of supercritical carbon dioxide is 2 wt% to 3 wt% of the material throughput. It should be noted that the values ​​in the above example are merely exemplary and should not be construed as limiting the scope of protection of this invention.

[0061] S22, the raw materials are sequentially crushed at the front end of the kneading and sealing zone 22, sealed by high pressure melt at the rear end of the kneading and sealing zone 22 and merged with supercritical fluid in the supercritical fluid injection zone 23, and sheared and mixed in the kneading reaction zone 24 to achieve desulfurization reaction.

[0062] The raw materials flow sequentially through each functional zone, ensuring the orderly conduct of the desulfurization reaction. The front end of the kneading and sealing zone 22 forcefully kneads and breaks down the rubber powder, increasing its density and continuing to raise the temperature, preparing it physically for subsequent reactions. The rear end of the kneading and sealing zone 22 forms a high-pressure melt seal through a reverse threaded element, effectively preventing the supercritical fluid from escaping upstream and confining it within the preset reaction zone. The kneading reaction zone 24, through the strong shearing, stretching, and folding action of the kneading disc 263, ensures thorough mixing and contact between the rubber powder and the supercritical fluid, achieving selective breakage of sulfur crosslinking bonds under relatively mild conditions while avoiding excessive degradation of the carbon-carbon backbone. This improves desulfurization efficiency while ensuring the retention rate of the reclaimed rubber's physical properties.

[0063] In a preferred embodiment, the supercritical fluid is supercritical carbon dioxide. Supercritical carbon dioxide has mild critical conditions, is easy to implement industrially, and has advantages such as being non-toxic, non-flammable, chemically inert, widely available, and inexpensive. Its excellent penetration and swelling capabilities can effectively reduce the density of the rubber crosslinking network, providing an ideal microenvironment for subsequent selective desulfurization.

[0064] Specifically, such as Figure 2As shown, the rubber desulfurization and recovery system also includes a supercritical fluid injection device 4, which is connected to the supercritical fluid injection zone 23 via a pipeline. The supercritical fluid injection device 4 can stably deliver supercritical fluid to the supercritical fluid injection zone 23 of the twin-screw extruder 2 at a set pressure and flow rate (e.g., ...). Figure 2 As indicated by arrow B, this ensures that the supercritical fluid reaches the required supercritical state at the injection point and is maintained at a constant supply, thereby providing a continuous and controllable fluid medium for the desulfurization reaction. This ensures sufficient contact and penetration between the supercritical fluid and the rubber matrix, which is beneficial to improving the stability and repeatability of the desulfurization reaction.

[0065] In this embodiment, as Figure 3 As shown, the twin-screw extruder 2 also includes a raw material conveying zone 21, which is located upstream of the kneading and sealing zone 22. The raw material conveying zone 21 is used at least to reduce the raw material flow rate by changing the screw pitch and to push the pretreated raw material toward the kneading and sealing zone 22 after pressure is established.

[0066] Furthermore, such as Figure 3 As shown, the twin-screw extruder 2 includes a pair of co-rotating screws 26. The screws 26 are provided with forward thread sections 261 in the raw material conveying zone 21, the kneading and sealing zone 22, and the supercritical fluid injection zone 23. Furthermore, the screws 26 are provided with a reverse thread section 262 between the rear end of the kneading and sealing zone 22 and the supercritical fluid injection zone 23, forming a reverse seal between the two zones. The forward thread section 261 ensures stable material delivery along the extrusion direction and establishes the necessary pressure, while the reverse thread section 262 forms a pressure barrier between the kneading and sealing zone 22 and the supercritical fluid injection zone 23, causing material to accumulate at the front end of the reverse thread section 262, forming a high-pressure melt dynamic seal. This ensures that the supercritical fluid is stably confined within the preset reaction zone, effectively preventing upstream leakage of subsequently injected supercritical fluid. This design relies on a purely mechanical structure, effectively preventing the supercritical fluid from flowing backwards, and achieving reliable sealing during continuous flow without additional power.

[0067] like Figure 3 As shown, the screw 26 is equipped with multiple kneading discs 263 in the kneading reaction zone 24. The kneading discs 263 are non-conveying screw elements. Their special geometry can exert strong shearing, stretching and folding forces when the material passes through, thereby achieving micro-dispersion and uniform mixing of the material. This is beneficial for the supercritical fluid to fully penetrate into the interior of the rubber matrix and fully interact with the sulfur crosslinking points, thereby effectively improving the efficiency and uniformity of the desulfurization reaction.

[0068] In this embodiment, the twin-screw extruder 2 has a body and an extrusion die. The screw 26 is located within the body, and the extrusion die is located at the downstream end of the body. The body provides a closed extrusion channel and reaction space for the screw 26, ensuring that the material is stably conveyed in a set direction within each functional zone and that the desulfurization reaction is completed; for example... Figure 2 As indicated by arrow C, the extrusion die is used to impart a specific cross-sectional shape to the desulfurized rubber melt, forming a continuous strip or sheet extrudate to facilitate subsequent cooling, pelletizing, and packaging processes. Through the cooperation between the machine body and the extrusion die, the system achieves continuous production from powdered raw materials to molded reclaimed rubber products.

[0069] Furthermore, the twin-screw extruder 2 also includes a stable output zone 25, located downstream of the kneading reaction zone 24, with the extrusion die positioned at the end of the stable output zone 25. As a transition area between the desulfurization reaction section and the forming section, the stable output zone 25 maintains pressure and temperature for the rubber melt that has completed the desulfurization reaction, preventing phase separation or degradation due to sudden pressure drops or uneven temperatures before the melt enters the extrusion die. This ensures the melt enters the extrusion die with a uniform flow rate and temperature distribution, thereby ensuring the dimensional stability and surface quality of the extruded product and achieving a smooth transition from the desulfurization reaction to product forming.

[0070] Building upon the aforementioned steps, step S3 specifically involves: extruding the reacted material through a twin-screw extruder 2 to obtain a rubber product. The desulfurized rubber melt is extruded through an extrusion die at the downstream end of the twin-screw extruder 2 to obtain a continuous strip or sheet-like rubber product with a specific cross-sectional shape, facilitating subsequent cooling, cutting, and packaging processes. Through pressure-holding and temperature maintenance in the stable output zone 25, the melt enters the die with a uniform flow rate and temperature distribution, ensuring the dimensional stability and surface quality of the extruded product and achieving continuous production from powdered raw materials to molded reclaimed rubber products.

[0071] In this embodiment, the rubber desulfurization and recovery system also includes a gas treatment device 3, which is connected to the twin-screw extruder 2 via a pipeline to treat the reaction tail gas. Figure 2 As indicated by arrow D, the reaction tail gas is collected simultaneously with the rubber product and then passed into gas treatment device 3 for purification. Since the desulfurization reaction and subsequent pressure release process generate complex reaction tail gas containing supercritical fluids, volatile organic compounds, sulfur-containing compounds, and condensable oils, direct emission not only causes environmental pollution but also wastes resources. By setting up gas treatment device 3 and connecting it to the twin-screw extruder 2 via pipeline, the reaction tail gas can be purified in multiple stages, achieving compliant emissions and the recovery and utilization of valuable components, thereby ensuring the safe, clean, and sustainable operation of the entire desulfurization and regeneration process.

[0072] Furthermore, such as Figure 4 As shown, the gas treatment device 3 includes a condenser 31, a scrubbing tower 32, and an activated carbon filter 33 connected in sequence, forming a three-stage purification system. Based on this, step S4 specifically involves: passing the reaction tail gas through the condenser 31, the scrubbing tower 32, and the activated carbon filter 33 in sequence for purification, so as to achieve the separation and extraction of pollutants. The gas treatment unit 3 consists of three stages: Condensation tank 31, the first stage unit, which pre-cools the high-temperature reaction exhaust gas from the rubber desulfurization system, liquefying condensable components (such as heavy hydrocarbons and oils) to achieve gas-liquid separation; Scrubbing tower 32, the second stage unit, removes residual aerosols, soluble acidic gases (such as sulfur-containing gases), and fine particulate matter by spraying scrubbing liquid (such as water or prepared scrubbing liquid) and counter-current contact between the scrubbing liquid and gas in the packing layer 325; and Activated carbon filter 33, the third stage unit, further removes residual volatile organic compounds (VOCs), odors, and trace pollutants from the gas through the physical adsorption of activated carbon. This three-stage treatment system effectively removes various complex pollutants from the desulfurization exhaust gas, overcoming the shortcomings of traditional single-treatment methods that result in incomplete purification, effectively reducing the risk of equipment scaling and clogging, lowering maintenance costs, and ensuring the long-term stable operation of the production line.

[0073] In this embodiment, as Figure 4 As shown, the condenser 31 has a first cavity. The condenser 31 is provided with a first air inlet 311 and a first air outlet 312 communicating with the first cavity. A condenser pipe 314 is provided inside the first cavity. The condenser pipe 314 is provided with a cooling water inlet 315 and a cooling water outlet 316. The first air inlet 311 is connected to the twin-screw extruder 2. The first cavity provides a cooling space for the high-temperature reaction exhaust gas. The first air inlet 311 and the first air outlet 312 guide the gas discharged from the twin-screw extruder 2 to flow through the condensation area along a set path. The built-in condenser pipe 314 introduces circulating cooling water through the cooling water inlet 315 and the cooling water outlet 316. The cooling water exchanges heat with the high-temperature gas through the pipe wall, so that condensable heavy hydrocarbons and oils are liquefied and separated. This not only recovers valuable oil resources, but also effectively avoids scaling and clogging problems caused by the condensation and deposition of such components in subsequent pipelines and equipment.

[0074] Furthermore, the condenser tube 314 is a spiral coil. By setting the condenser tube 314 as a spiral coil, the effective length of the heat exchange pipeline is effectively extended within the limited space of the first cavity, increasing the heat exchange area between the cooling water and the high-temperature gas, thereby improving the condensation efficiency. At the same time, the spiral structure causes the high-temperature gas to continuously change its flow direction as it flows through the gaps in the coil, enhancing gas turbulence and mixing, promoting the collision and liquefaction separation of condensable components on the tube wall surface, and ensuring that heavy oil and hydrocarbon components are fully condensed and recovered.

[0075] like Figure 4 As shown, the first air inlet 311 and the first air outlet 312 are respectively located on both sides of the condenser tank 31; furthermore, the liquid flow direction in the condenser tube 314 is from bottom to top. The first air inlet 311 and the first air outlet 312 located on both sides allow the high-temperature exhaust gas to pass through the entire condensation space along a transverse path within the cavity, extending the residence time of the gas in the condenser tube 314 area, avoiding airflow short-circuiting, and ensuring sufficient heat exchange. At the same time, the cooling water in the condenser tube 314 adopts a bottom-up flow direction, forming cross-flow or counter-flow contact with the high-temperature exhaust gas, which is conducive to maintaining a uniform temperature of the heat exchange tube wall, avoiding local overheating that leads to a decrease in condensation efficiency, and allowing condensable heavy components to be fully condensed and liquefied in the passage path, improving condensation recovery efficiency and effectively reducing the processing burden of subsequent purification units.

[0076] Furthermore, the condenser 31 is also equipped with a condensate outlet 313 connected to the first chamber. The condensable oils and water-soluble components that have been liquefied and separated and collected at the bottom of the tank are discharged from the chamber in a timely manner through the condensate outlet 313. This not only achieves efficient recovery and collection of valuable oil resources, but also prevents the problem of excessive liquid level caused by long-term accumulation of condensate in the chamber, which could submerge part of the condenser tubes 314 and affect the heat exchange efficiency, thus ensuring the continuous and stable operation of the condenser 31.

[0077] In this embodiment, as Figure 4 As shown, the scrubbing tower 32 has a second cavity. The scrubbing tower 32 is equipped with a second air inlet 321, a second air outlet 322, and a scrubbing liquid inlet 323, all of which are connected to the second cavity. The second air inlet 321 is connected to the first air outlet 312. The second cavity provides reaction space for gas-liquid two-phase contact. The second air inlet 321 introduces the exhaust gas from the condenser 31 into the cavity, and the scrubbing liquid inlet 323 introduces the scrubbing liquid into the cavity, allowing the scrubbing liquid to fully contact the gas. This ensures that acidic gases, aerosols, and fine particulate matter in the exhaust gas are captured in a timely manner, achieving effective purification of the reaction exhaust gas. The second air outlet 322 discharges the purified gas to the next stage of processing.

[0078] Furthermore, the scrubbing tower 32 is equipped with a packing layer 325, which has voids. The numerous voids formed in the packing layer 325 effectively increase the contact area between the gas and the scrubbing liquid and prolong the contact time. When the exhaust gas passes through the packing layer 325, the gas flow is repeatedly dispersed and converged in the voids of the packing, forming a highly turbulent state; at the same time, the scrubbing liquid spreads evenly on the surface of the packing to form a liquid film. In this state, the gas and liquid phases are in full contact inside the packing layer 325 with the help of the voids in the packing, which enhances the mass transfer process and enables the effective absorption and capture of acidic gases, aerosols, and fine particulate matter.

[0079] Based on the packing layer 325, a second air inlet 321 is located below the packing layer 325, and a second air outlet 322 is located above the packing layer 325. This forces the exhaust gas to pass through the packing layer 325 from bottom to top, forming a counter-current contact with the washing liquid distributed from top to bottom. This counter-current operation maintains a high mass transfer driving force throughout the entire height of the packing layer 325, ensuring that the exhaust gas continues to be in contact with fresh washing liquid during its ascent. This fully utilizes the purification efficiency of the packing layer 325, ensuring that acidic gases, aerosols, and fine particulate matter are adequately absorbed and efficiently captured during passage.

[0080] Based on the packing layer 325, the scrubbing tower 32 is equipped with multiple nozzles 326 connected to the scrubbing liquid inlet 323, located above the packing layer 325. These evenly distributed nozzles 326 spray the scrubbing liquid uniformly onto the top of the packing layer 325, ensuring uniform distribution of the scrubbing liquid across the entire tower cross-section. This effectively avoids the problem of reduced gas-liquid contact area caused by unwetted packing material due to flow deviation or spray dead zones. Simultaneously, the nozzles 326's location above the packing layer 325 allows the scrubbing liquid to naturally penetrate downwards by gravity, forming a continuously renewing liquid film on the packing surface. This maintains a stable gas-liquid contact interface and effectively prevents fine particulate matter entrained in the exhaust gas from depositing and clogging the nozzles 326, ensuring the long-term reliability of the equipment.

[0081] Furthermore, the scrubbing tower 32 is also equipped with a first drain port 324 connected to the second chamber. Waste liquid, suspended solids, and sediment generated after absorbing pollutants are promptly discharged from the tower through the first drain port 324, enabling periodic or continuous sludge removal. On the one hand, this effectively controls the liquid level inside the tower, preventing excessively high liquid levels from submerging the second air inlet 321 or interfering with gas flow due to liquid level fluctuations. On the other hand, it promptly removes accumulated solid particles and reaction products from the packing layer 325, avoiding increased system pressure drop and decreased absorption efficiency caused by packing void blockage, thereby ensuring the long-term, stable, and efficient operation of the scrubbing tower 32.

[0082] In an optional embodiment, the scrubbing tower 32 is also equipped with a circulation pipeline, on which a circulation pump 327 is installed for recycling a portion of the scrubbing liquid. This improves the utilization efficiency of the scrubbing liquid, reduces the consumption of fresh scrubbing liquid and waste discharge, thereby lowering operating costs. Simultaneously, this circulation operation can be coordinated with periodic sludge discharge to achieve effective renewal and concentration of the scrubbing liquid, helping to extend the effective service life of a single batch of scrubbing liquid and further improving the overall removal efficiency of pollutants.

[0083] In this embodiment, the activated carbon filter 33 forms a third cavity, within which an activated carbon adsorption layer 333 is disposed. The activated carbon filter 33 has a third air inlet 331 and a third air outlet 332 communicating with the third cavity. The third air inlet 331 is connected to the second air outlet 322. By forming the third cavity, the activated carbon filter 33 provides a space and airflow channel for the deep adsorption of residual pollutants. The third air inlet 331 and the second air outlet 322 communicate to allow the exhaust gas, after condensation and washing, to be introduced into the third cavity in a sealed manner, ensuring that the gas can flow through the activated carbon adsorption layer 333 along a set path. The activated carbon adsorption layer 333 fills the third cavity, utilizing the rich microporous structure and large specific surface area of ​​activated carbon to physically adsorb and retain residual volatile organic compounds, odors, and trace pollutants in the exhaust gas. The third air outlet 332 discharges the finally purified clean gas from the device.

[0084] Furthermore, such as Figure 5 As shown, the third cavity is provided with an annular gas collecting chamber 334 and a core gas collecting pipe 335. The annular gas collecting chamber 334 is arranged around the periphery of the activated carbon adsorption layer 333, and the core gas collecting pipe 335 passes through the activated carbon adsorption layer 333. The annular gas collecting chamber 334 is provided with a first vent, and the core gas collecting pipe 335 is provided with a second vent. The first vent is connected to the second vent through the activated carbon adsorption layer 333. The third air inlet 331 is connected to the top of the annular gas collecting chamber 334, and the third air outlet 332 is connected to the top of the core gas collecting pipe 335. The activated carbon filter 33, through the arrangement of an annular gas collection chamber 334 and a core gas collection pipe 335, allows exhaust gas to enter the top of the annular gas collection chamber 334 via the third inlet 331. The gas then diffuses evenly through the first pore to the periphery of the activated carbon adsorption layer 333, where it is fully adsorbed and purified as it radially passes through the layer. The purified gas is then collected through the second pore into the core gas collection pipe 335 and finally discharged through the third outlet 332. This radial flow pattern from the outside in effectively increases the contact area between the gas and the activated carbon, avoiding localized penetration and uneven adsorption, thus improving the utilization efficiency of the activated carbon adsorption layer 333 and ensuring a stable and reliable deep adsorption effect.

[0085] Specifically, the first vent is located in the middle and / or bottom of the side wall of the annular gas collection chamber 334, allowing the exhaust gas entering the annular gas collection chamber 334 to first diffuse downwards within the annular space, and then penetrate radially into the activated carbon adsorption layer 333 from the middle or bottom of the side wall. This helps to achieve a relatively uniform distribution of the exhaust gas along the axial direction of the adsorption layer, avoiding local adsorption saturation caused by concentrated gas intake, thereby improving the overall utilization efficiency of the adsorption layer and extending the service life of the activated carbon. The second vent is located in the middle and / or bottom of the side wall of the core gas collection pipe 335, allowing the purified gas to converge into the core gas collection pipe 335 from various height positions of the adsorption layer, thereby ensuring a relatively uniform radial flow of airflow, avoiding airflow short-circuiting caused by local convergence, and ensuring that the entire cross-section of the adsorption layer can effectively participate in the purification process.

[0086] like Figure 5 As shown, a horizontal exhaust pipe 337 is provided at the top of the core gas collection pipe 335. The horizontal exhaust pipe 337 extends to the outside of the activated carbon filter 33, and one end of the horizontal exhaust pipe 337 extends to the outside to form a third air outlet 332. This allows the purified gas that gathers upward at the top of the core gas collection pipe 335 to be smoothly discharged through the horizontal exhaust pipe 337, ensuring a smooth gas flow path. It also avoids the installation height limitations or pipe interference problems caused by direct vertical discharge of gas at the top of the filter, and facilitates flexible connection with downstream pipelines.

[0087] In addition, the activated carbon filter 33 is also provided with a second drain port 336 that communicates with the third chamber. The second drain port 336 can periodically discharge some of the fine particulate matter trapped in the activated carbon adsorption layer 333, as well as condensate or dust accumulations that may be generated during the adsorption process, to prevent deposits from accumulating at the bottom of the chamber and blocking the airflow channels of the activated carbon adsorption layer 333, and at the same time prevent condensate from wetting the activated carbon for a long time and reducing its adsorption capacity.

[0088] In a preferred embodiment, such as Figure 4 As shown, the first air inlet 311 of the condenser 31 is connected to the twin-screw extruder 2 via a short connecting pipe 34, and the third air inlet 331 of the activated carbon filter 33 is connected to the second air outlet 322 of the scrubbing tower 32 via a long connecting pipe 35. The direct connection of the condenser 31 to the twin-screw extruder 2 via the short connecting pipe 34 shortens the transport path of the reaction tail gas, enabling the condenser 31 to process the reaction tail gas in a timely manner. This helps prevent premature condensation and scaling of high-temperature waste gas in the pipes, which would affect gas flow. The connection of the activated carbon filter 33 to the scrubbing tower 32 via the long connecting pipe 35 allows for natural heat dissipation and condensation effects through the pipes, reducing the waste gas temperature and separating water vapor, thereby minimizing the impact of moisture on the adsorption performance of the activated carbon.

[0089] The rubber desulfurization and recovery system of this invention effectively overcomes the problems of inconsistent initial state of raw materials and uneven heat transfer by preheating and dehumidifying the raw materials and combining this with the kneading and sealing zone 22 in the twin-screw extruder 2. Specifically, the raw materials enter the extruder after being preheated and dried by the pretreatment device 1. This not only avoids the increase in extrusion load caused by residual moisture and helps eliminate safety hazards, but also ensures that the rubber powder reaches a relatively uniform temperature before entering the desulfurization section, thereby eliminating fluctuations in initial process conditions caused by seasonal changes, storage conditions, and differences in pretreatment processes. At the same time, the kneading and sealing zone 22 strongly kneads and crushes the material, improving the uniformity of rubber powder distribution in the screw 26, which is conducive to the uniform establishment of the subsequent temperature field and alleviates the problems of local overheating and hot spot concentration caused by the extremely low thermal conductivity of rubber powder from the source.

[0090] Secondly, the high-pressure dynamic seal formed by the kneading and sealing zone 22 creates conditions for the stable injection of supercritical fluid, and utilizes supercritical fluid-assisted desulfurization to promote the selective breaking of sulfur crosslinking bonds, effectively reducing excessive degradation of the main chain. Specifically, the kneading and sealing zone 22 establishes pressure inside the extruder with the help of a reverse screw element, forming an effective seal for the melt, preventing the supercritical fluid from escaping backward along the screw 26, and ensuring the stability of pressure and temperature within the supercritical fluid injection zone 23. Simultaneously, the supercritical fluid has excellent fluidity and permeability, which can fully swell the rubber crosslinking network, allowing the desulfurizing agent to penetrate uniformly and promote the breaking of sulfur crosslinking bonds under relatively mild conditions, thereby effectively improving desulfurization selectivity and maintaining a high property retention rate in the reclaimed rubber. Furthermore, the excellent mass and heat transfer capabilities of the supercritical fluid also promote the timely discharge of decomposition products, improving the operational stability of the extrusion process.

[0091] Furthermore, through the aforementioned technical means, while effectively reducing the generation of harmful byproducts, continuous and green desulfurization and regeneration of waste rubber are achieved. This enables effective control of the raw material state, uniformity of the temperature field, and gentle desulfurization assisted by supercritical fluid, avoiding local overheating and effectively suppressing the generation of sulfur-containing vapors, volatile organic compounds, and heavy condensable components at the source. Based on this, a gas treatment device 3 is installed, particularly a multi-stage purification system consisting of a condenser tank 31, a scrubbing tower 32, and an activated carbon filter 33 connected in sequence. This system effectively treats the tail gas generated during the desulfurization reaction, helping to alleviate problems such as equipment scaling, increased maintenance burden, excessive pollutant emissions, and operator health exposure.

[0092] In the description of this invention, "processor" can include hardware, software, or a combination of both. A processor can be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. A processor has data and / or signal processing capabilities. A processor can be implemented in software, in hardware, or a combination of both. Non-transitory computer-readable storage media includes any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc.

[0093] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by hardware related to computer program instructions. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0094] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for desulfurizing and recovering rubber, characterized in that, The rubber desulfurization and recovery method includes: The raw materials are preheated and dehumidified. The raw materials are crushed and then supercritical fluid is introduced into the crushed raw materials, followed by shear mixing to achieve the desulfurization reaction. The reacted material is then extruded to obtain a rubber product.

2. The rubber desulfurization and recovery method according to claim 1, characterized in that, The "preheating and dehumidification treatment of raw materials" includes: preheating and dehumidifying the raw materials to bring them to a preset temperature and humidity and maintain them for a preset time; The preset temperature is 110℃~130℃, the preset humidity is less than or equal to 0.1%, and the preset duration is 3 minutes to 8 minutes.

3. The rubber desulfurization and recovery method according to claim 1, characterized in that, The aforementioned "introducing supercritical fluid into the crushed raw material" includes: Supercritical fluid is introduced into the crushed raw material at a preset ratio; The injection rate of supercritical fluid is 2 wt% to 3 wt% of the material throughput.

4. The rubber desulfurization and recovery method according to claim 1, characterized in that, The rubber desulfurization and recovery method also includes: The reaction exhaust gas is collected while obtaining the rubber product, and the reaction exhaust gas is then purified.

5. The rubber desulfurization and recovery method according to claim 4, characterized in that, The "purification treatment of the reaction tail gas" includes: The reaction exhaust gas is purified step by step through condensation, washing, and filtration to achieve the separation and extraction of pollutants.

6. A rubber desulfurization and recovery system, characterized in that, The rubber desulfurization and recovery system includes a processor for performing the rubber desulfurization and recovery method according to any one of claims 1 to 5.

7. The rubber desulfurization and recovery system according to claim 6, characterized in that, The rubber desulfurization and recovery system includes: a pretreatment device (1), which is used at least for preheating and dehumidifying the raw materials; and a twin-screw extruder (2), which includes, in sequence along the material flow direction: a kneading and sealing zone (22), a supercritical fluid injection zone (23), and a kneading reaction zone (24); wherein, the kneading and sealing zone (22) is used at least for kneading and crushing the raw materials and forming a high-pressure zone to achieve dynamic sealing of the melt, and the kneading reaction zone (24) is used at least for shearing and mixing the materials to promote the desulfurization reaction; The rubber desulfurization and recovery method includes: feeding the raw material into the pretreatment device (1) for preheating and dehumidification; feeding the raw material into the twin-screw extruder (2) and injecting supercritical fluid into the supercritical fluid injection zone (23); causing the raw material to be crushed at the front end of the kneading and sealing zone (22), merged with supercritical fluid in the supercritical fluid injection zone (23) under the high-pressure melt sealing action at the rear end of the kneading and sealing zone (22), and sheared and mixed in the kneading reaction zone (24) to achieve desulfurization reaction; and extruding the reacted material through the twin-screw extruder (2) to obtain rubber products.

8. The rubber desulfurization and recovery system according to claim 7, characterized in that, The pretreatment device (1) includes an infrared spiral drying and heating drum; and / or The kneading and sealing zone (22) is also used to heat the raw materials and increase pressure; and / or The twin-screw extruder (2) further includes a raw material conveying zone (21) located upstream of the kneading and sealing zone (22); and / or The twin-screw extruder (2) further includes a stable output zone (25) located downstream of the kneading reaction zone (24).

9. The rubber desulfurization and recovery system according to claim 7, characterized in that, The twin-screw extruder (2) includes a pair of screws (26) meshing in the same direction. The screws (26) are provided with forward thread sections (261) in both the kneading and sealing zone (22) and the supercritical fluid injection zone (23). The screws (26) are provided with reverse thread sections (262) between the kneading and sealing zone (22) and the supercritical fluid injection zone (23) to form a reverse seal between the two zones through the reverse thread sections (262).

10. The rubber desulfurization and recovery system according to claim 9, characterized in that, The screw (26) is provided with a plurality of kneading discs (263) in the kneading reaction zone (24); and / or The twin-screw extruder (2) has a body and an extrusion die, the screw (26) is located in the body, and the extrusion die is located at the downstream end of the body.

11. The rubber desulfurization and recovery system according to claim 7, characterized in that, The rubber desulfurization and recovery system also includes a gas treatment device (3), which is connected to the twin-screw extruder (2) via a pipeline to treat the reaction tail gas.

12. The rubber desulfurization and recovery system according to claim 11, characterized in that, The gas processing device (3) includes a condenser (31), a scrubbing tower (32), and an activated carbon filter (33) connected in sequence.

13. The rubber desulfurization and recovery system according to claim 12, characterized in that, The condenser (31) has a first cavity, and the condenser (31) is provided with a first air inlet (311) and a first air outlet (312) communicating with the first cavity. The first cavity is provided with a condenser pipe (314), and the condenser pipe (314) is provided with a cooling water inlet (315) and a cooling water outlet (316). The first air inlet (311) is connected to the twin-screw extruder (2). The washing tower (32) has a second cavity. The washing tower (32) is provided with a second air inlet (321), a second air outlet (322) and a washing liquid inlet (323) that are connected to the second cavity. The second air inlet (321) is connected to the first air outlet (312). The activated carbon filter (33) has a third cavity, and an activated carbon adsorption layer (333) is provided in the third cavity. The activated carbon filter (33) has a third air inlet (331) and a third air outlet (332) that are connected to the third cavity. The third air inlet (331) is connected to the second air outlet (322).

14. The rubber desulfurization and recovery system according to claim 13, characterized in that, The condenser (314) is a spiral coil; and / or The liquid flow direction in the condenser (314) is from bottom to top; and / or The condenser (31) is also provided with a condensate outlet (313) that communicates with the first cavity.

15. The rubber desulfurization and recovery system according to claim 13, characterized in that, The washing tower (32) is provided with a packing layer (325), and the packing layer (325) has voids; wherein, The second air inlet (321) is located below the packing layer (325), and the second air outlet (322) is located above the packing layer (325); and / or The washing tower (32) is provided with a plurality of nozzles (326) that communicate with the washing liquid inlet (323), and the nozzles (326) are located above the packing layer (325).

16. The rubber desulfurization and recovery system according to claim 13, characterized in that, The third cavity is provided with an annular gas collection chamber (334) and a core gas collection pipe (335). The annular gas collection chamber (334) is arranged around the periphery of the activated carbon adsorption layer (333), and the core gas collection pipe (335) passes through the activated carbon adsorption layer (333). The annular gas collecting chamber (334) is provided with a first gas hole, and the core gas collecting pipe (335) is provided with a second gas hole. The first gas hole is connected to the second gas hole through the activated carbon adsorption layer (333). The third air inlet (331) is connected to the top of the annular air collection chamber (334), and the third air outlet (332) is connected to the top of the core air collection pipe (335).

17. The rubber desulfurization and recovery system according to claim 7, characterized in that, The supercritical fluid is supercritical carbon dioxide; and / or The rubber desulfurization and recovery system also includes a supercritical fluid injection device (4), which is connected to the supercritical fluid injection zone (23) via a pipeline.

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