One-stage internal and external flow-dividing partition temperature control waste rubber and plastic pyrolysis system and method

Abstract

This invention discloses a one-stage, internally and externally guided, zoned temperature-controlled waste rubber and plastic pyrolysis system and method, including a dual-stage sealed feeding module, a one-stage internally heated pyrolysis spiral, a pyrolysis oil and gas outlet, a pyrolysis solid phase outlet, a high-temperature combustion furnace, a flue gas swirl mixing chamber, internal and external flue gas guiding modules, an internal-external heated flue gas connecting pipe, an external heating module, a flue gas circulation fan, a circulating flue gas module, and a zoned temperature measurement module. Addressing the temperature requirements at each stage of the waste rubber and plastic pyrolysis process and the characteristics of high-quality product generation, the system designs a flue gas swirl mixing chamber and internal and external flue gas guiding modules. Combined with the one-stage internally heated pyrolysis spiral structure and the external heating module, this allows for orderly temperature rise of the waste rubber and plastic during pyrolysis, precise and controllable temperature in the pyrolysis zone, increased oil yield, and reduced oil content in the solid phase products due to the high temperature in the conditioning zone, significantly increasing the added value of the products. This invention has the advantages of simple structure, precise zoned temperature control, flexible system adjustment, and high-quality pyrolysis products.

Description

Technical Field

[0001] This invention relates to the field of waste rubber and plastic pyrolysis resource utilization technology, and in particular to a one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis system and method. Background Technology

[0002] Waste rubber and plastic pyrolysis refers to the process of decomposing waste rubber and plastic into combustible gas, pyrolysis oil, and pyrolysis char by heating in an oxygen-free atmosphere.

[0003] There are many methods for pyrolysis of waste rubber and plastics, such as catalytic pyrolysis, vacuum pyrolysis, hydropyrolysis, low-temperature pyrolysis, superheated steam stripping pyrolysis, and co-pyrolysis. Catalytic pyrolysis uses catalysts to directionally regulate product composition; vacuum pyrolysis relies on a low-oxygen environment to improve oil purity; hydropyrolysis uses hydrogen reduction to optimize fuel quality; low-temperature pyrolysis focuses on the recovery of solid products such as carbon black; superheated steam stripping pyrolysis uses steam to enhance heat and mass transfer; and co-pyrolysis improves reaction characteristics through the synergistic effect of multiple raw materials. Each method addresses different challenges, such as product directionality, purity improvement, and energy consumption optimization.

[0004] Pyrolysis reactors mainly consist of moving bed, fixed bed, rotary kiln, and fluidized bed reactors. Moving bed reactors achieve high process control and product purity through continuous material movement and counter-current contact with the heat carrier, but the equipment is complex, the investment is high, and the requirements for raw material uniformity are high. Fixed bed reactors adopt a static material stacking pyrolysis mode, which is simple in structure, low in investment, and easy to operate. Rotary kiln reactors achieve material tumbling and heating through the rotation of the cylinder, which has strong resistance to impurities, but low thermal efficiency. Fluidized bed reactors rely on gas fluidization to achieve efficient heat and mass transfer, with high thermal efficiency, but strict requirements on raw material particle size, requiring the matching fine crushing equipment.

[0005] For example, Chinese patent document CN114540056A discloses a waste rubber and plastic pyrolysis treatment device and its treatment method, which includes a screw feeder, a combined internal and external heating pyrolysis furnace, a water-cooled auger and separation device, and a pyrolysis product collection bin connected in sequence.

[0006] Chinese patent document CN121064869A discloses a waste rubber and plastic pyrolysis system and its application, including: a feeding unit comprising a feeding hopper, a material conveying mechanism, and an oxygen-free protection mechanism; a pyrolysis reaction unit comprising a primary pyrolysis reactor and a secondary pyrolysis reactor; and a product recovery structure comprising a pyrolysis gas purification and condensation device. Although waste rubber and plastic pyrolysis has high economic and environmental value, it is technically challenging and requires sophisticated equipment and systems. Existing technologies and equipment suffer from poor continuity, low oil yield, high energy consumption, and small processing capacity. Therefore, there is an urgent need to develop continuous, stable, efficient, and large-scale waste rubber and plastic pyrolysis technologies and systems. Summary of the Invention

[0007] This invention provides a one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis system and method, which has the advantages of simple structure, precise zoned temperature control, flexible system adjustment, and high quality of pyrolysis products.

[0008] A single-stage, internal and external flow-guided, zoned temperature-controlled waste rubber and plastic pyrolysis system includes: A dual-stage sealed feeding module is installed at the feed inlet of the one-stage internal heating pyrolysis spiral to achieve sealed feeding of materials and self-cleaning of the feed inlet; A one-stage internal heating pyrolysis spiral is set with a preheating zone, a pyrolysis zone, and a conditioning zone along the material conveying direction. High-temperature flue gas flows inside, and spiral blades with different pitches are set in each zone on the outside for internal heating and conveying of pyrolysis materials. The pyrolysis oil and gas outlet is located in the middle of the rear end of the one-stage internal heating pyrolysis spiral, and is used to discharge the high-temperature oil and gas generated by the pyrolysis of waste rubber and plastic. The pyrolysis solid phase discharge port is located at the rear end of the one-stage internal heating pyrolysis spiral and is used to discharge the solid products generated by the pyrolysis of waste rubber and plastic. A high-temperature combustion furnace is used to burn the non-condensable gases produced by pyrolysis to generate high-temperature flue gas; The flue gas swirl mixing chamber is used to orderly mix the high-temperature flue gas generated by the high-temperature combustion furnace with the recirculated flue gas output from the external heating module. After mixing, the flue gas enters the one-stage internal heating pyrolysis spiral. The flue gas internal and external flow guiding module is set inside the one-stage internal heating pyrolysis spiral. High-temperature flue gas flows inside the front section and through the middle flue gas internal and external flow guiding component, high-temperature flue gas flows outside the rear section, realizing zoned temperature control of the one-stage internal heating pyrolysis spiral and improving the temperature of the rear section of the pyrolysis spiral. The internal-external heating flue gas connection pipe is used to connect the flue gas outlet of the one-stage internal heating pyrolysis spiral and the flue gas inlet of the external heating module; The external heating module is installed outside the one-stage internal heating pyrolysis spiral. Its flue gas flows in the opposite direction to the material conveying direction, heating the material from the outside and reducing the exhaust temperature. Flue gas recirculation fan is used to drive flue gas to flow within the one-stage internal heating pyrolysis spiral and external heating module; The circulating flue gas module is used for controlling the amount of recirculated flue gas and regulating the temperature of pyrolysis flue gas, so as to achieve precise control of the pyrolysis temperature of waste rubber and plastic. The zone temperature measurement module is used to measure the pyrolysis temperature of materials in the preheating zone, pyrolysis zone, and conditioning zone.

[0009] To facilitate assembly, debugging, and overall hoisting and transportation within the factory, the bottom of the one-stage internal and external flow-diverting zone temperature-controlled waste rubber and plastic pyrolysis system is equipped with an integrated skid-mounted base.

[0010] To achieve high-value utilization of waste rubber and plastics through pyrolysis, this invention addresses the temperature requirements at each stage of the pyrolysis process and the characteristics of high-quality product generation. By designing a flue gas swirl mixing chamber and internal and external flue gas guiding modules, combined with a one-stage internal heating pyrolysis spiral structure and an external heating module, the waste rubber and plastics can be heated in an orderly manner during pyrolysis. The temperature in the pyrolysis zone is precisely controllable, improving the oil yield. The high temperature in the conditioning zone reduces the oil content of the solid products, significantly increasing the added value of the products.

[0011] The pyrolysis of waste rubber and plastic is carried out in a slightly negative pressure oxygen-free environment. In order to achieve sealed feeding, the dual-stage sealed feeding module in this invention includes a small hopper, a horizontal feeding screw and an inclined feeding double screw. The horizontal feeding screw and the inclined feeding twin screw are arranged vertically. The horizontal feeding screw is a shaftless screw with a screw length greater than 10 times the screw pitch. During the feeding process, the horizontal feeding screw performs extrusion conveying and acts as a material seal. The inclined feeding twin screw has a self-cleaning function to prevent the feed inlet from clogging. The material temperature at the inlet is low, while the pyrolysis unit dissipates pyrolysis oil and gas. At the material inlet, the material and pyrolysis oil and gas are prone to sticking and clogging. Therefore, the inclined twin screw with self-cleaning function is designed to avoid material blockage at the feed inlet.

[0012] In order to achieve the conveying and heating during the pyrolysis of waste rubber and plastic, the one-stage internal heating pyrolysis spiral consists of a central flue gas inlet and a flue gas outlet. At the same time, along the conveying direction of the pyrolysis material, it includes, in sequence, a feeding reverse spiral blade, a preheating zone spiral blade, a pyrolysis zone spiral blade, a conditioning zone spiral blade, and a discharging reverse spiral blade. Because oil and gas are released during the pyrolysis of waste rubber and plastic, the pyrolysis rate in the tempering zone has reached 90-95%, and the proportion of solid products is less than 40%. Therefore, the pitch of the spiral blades in the preheating zone and the tempering zone is gradually reduced. The pitch of the spiral blades in the tempering zone is 50%-60% of the pitch of the spiral blades in the preheating zone.

[0013] Heat exchange nails are installed on the flue gas side of the quenching zone to increase the heating temperature of the spiral blades in the quenching zone.

[0014] In the single-stage internal heating pyrolysis spiral, high-temperature flue gas flows inside, heating the spiral blades, which then further heat the waste rubber and plastic material. The spiral blades both transport and agitate the material and heat it; here, the spiral blades act like reinforced heat exchange fins, significantly increasing the heat exchange area. In the conditioning zone, the spiral blade pitch decreases, increasing the heat exchange area. Combined with the enhanced heat transfer effect of the flue gas-side heat exchange pins, the spiral blade temperature also rises. This helps to increase the material temperature in the conditioning zone and reduce the oil content of the solid products.

[0015] In order to reduce the consumption of non-condensable gas in the waste rubber and plastic pyrolysis system and improve the combustion efficiency, a high-temperature combustion furnace was designed to burn off the organic matter in the non-condensable gas at high temperature.

[0016] Preferably, in the flue gas swirl mixing chamber, the high-temperature flue gas (1600-1800°C) generated by the high-temperature combustion furnace enters from the center, while the recirculated flue gas (450-480°C) enters tangentially. After swirling and mixing, the flue gas has a high temperature at the center and a low temperature at the periphery. This high-temperature-at-the-center and low-temperature-at-the-periphery flow field structure reduces heat loss and also facilitates the orderly utilization of flue gas in subsequent internal and external flue gas guiding modules.

[0017] To further increase the material temperature in the conditioning zone while ensuring controllable material temperature in the pyrolysis zone, an internal and external flue gas guiding module was designed. This module includes a front flue pipe, a front central flue gas zone, a front outer flue gas zone, a central flue gas guiding component, a rear flue pipe, a rear outer flue gas zone, a rear central flue gas zone, and internal insulation within the rear flue pipe. Through the flue gas internal and external flow guiding module, the flue gas coming out of the flue gas swirl mixing chamber enters the front central flue gas zone and the front outer flue gas zone respectively. Since the temperature of the flue gas center after swirl mixing is high, the flue gas temperature in the front central flue gas zone is higher than that in the front outer flue gas zone. After passing through the middle flue gas internal and external flow guiding component, the high-temperature flue gas in the front central flue gas zone is transported to the rear outer flue gas zone, thereby increasing the temperature of the rear section of the pyrolysis spiral.

[0018] Since the pyrolysis temperature of waste rubber and plastics is 420~450℃, the material needs to rise from ambient temperature to the pyrolysis temperature to move from the preheating zone to the pyrolysis zone. However, the amount of solid products decreases after the pyrolysis oil and gas are released. The material in the conditioning zone needs to be heated by 100~150℃. Preferably, the flue gas volume in the outer flue gas zone is 4~5 times that in the central flue gas zone to ensure the pyrolysis temperature of the material in the pyrolysis zone. Because the flue gas volume in the central flue gas zone is small, the volume in the outer flue gas zone is also small. To increase the flow rate in the outer flue gas zone, the diameter of the rear flue pipe is increased. Simultaneously, insulation is installed inside the rear flue pipe to reduce the heat transfer from the outer flue gas zone to the central flue gas zone, thereby improving the heating effect of the flue gas in the flue gas guiding modules.

[0019] By setting up flue gas internal and external flow guiding modules, the temperature of the preheating zone, pyrolysis zone and conditioning zone can be precisely controlled. Generally, in order to increase the temperature of the conditioning zone, the temperature of the preheating zone and pyrolysis zone will inevitably be increased, resulting in the inability to accurately control the pyrolysis temperature. Excessively high pyrolysis temperature will reduce the oil yield, increase the heavy components in the pyrolysis oil, and reduce the oil quality.

[0020] To improve the heat utilization of flue gas, an external heating module is installed. The external heating module includes an external heating flue gas inlet, guide vanes, heat exchange pins in the conditioning zone, heat exchange pins in the pyrolysis zone, heat exchange pins in the preheating zone, an external heating flue gas outlet, and external insulation.

[0021] Since the pyrolysis material is mainly located in the lower part of the pyrolysis unit, preferably, the heat exchange nails in the conditioning zone, pyrolysis zone, and preheating zone are arranged in the lower part of the outer heating module cylinder wall. After the pyrolysis zone, the solid products decrease. More preferably, the heat exchange nails in the pyrolysis zone have the largest circumferential proportion, while those in the conditioning zone have the smallest. The arrangement of the heat exchange nails enhances heat transfer on the flue gas side, improving the flue gas heat utilization rate.

[0022] To reduce exhaust gas temperature and simplify flue gas pipelines, preferably, the flue gas from the external heating module flows in the opposite direction to the material conveying direction, and the flue gas discharged from the center of the one-stage internal heating pyrolysis spiral enters the external heating module from the external heating flue gas inlet of the conditioning zone.

[0023] To further improve the heat utilization of the flue gas, a circulating flue gas module is set up to regulate the pyrolysis temperature by controlling the flue gas volume of the pyrolysis system. The circulating flue gas module includes a recirculation pipe, a recirculation flue gas flow meter, a recirculation regulating valve, an exhaust pipe, an exhaust flue gas flow meter, and an exhaust flue gas regulating valve. One end of the recirculation pipe is connected to the outlet of the flue gas recirculation fan, and the other end is connected to the flue gas swirl mixing chamber; The total flue gas volume of the pyrolysis system is calculated based on the recirculated flue gas flow rate and the exhaust flue gas flow rate. The recirculated flue gas volume is then controlled by adjusting the exhaust flue gas regulating valve and the recirculation regulating valve.

[0024] The zone temperature measurement module can display the pyrolysis temperature of materials in the preheating zone, pyrolysis zone, and conditioning zone, providing data for the adjustment of the circulating flue gas module.

[0025] Increasing the system flue gas volume can increase the flue gas velocity, increase the heat transfer coefficient on the flue gas side, reduce the exhaust gas temperature, and reduce system energy consumption.

[0026] A one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis method, based on the aforementioned one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis system, includes the following steps: (1) Waste rubber and plastic materials are conveyed to a single-stage internal heating pyrolysis spiral through a double-stage sealed feeding module; (2) The material is conveyed by a one-stage internal heating and pyrolysis screw conveyor and passes through the preheating zone, pyrolysis zone and conditioning zone in sequence, and the material is heated and pyrolyzed; (3) The material temperature gradually increases from the preheating zone to the conditioning zone. By setting up internal and external flue gas guiding modules, the internal heating flue gas temperature first decreases and then increases. (4) Adjust the burner load and recirculated flue gas volume of the high-temperature combustion furnace according to the material quantity, thereby controlling the pyrolysis temperature of different zones; (5) The oil and gas generated from the pyrolysis of waste rubber and plastic should be discharged from the pyrolysis oil and gas outlet in a timely manner to avoid secondary reactions caused by prolonged residence; (6) After most of the oil and gas are discharged, the temperature of the conditioning zone is increased so that the solid products are completely discharged from the pyrolysis solid outlet.

[0027] In step (3), the pyrolysis temperature of the conditioning zone is increased by setting the flue gas internal and external flow guiding module, which improves the physical properties of the solid products and avoids the increase of heavy products of pyrolysis oil and gas caused by excessively high temperature in the pyrolysis zone, thus achieving zoned temperature control.

[0028] Compared with the prior art, the present invention has the following beneficial effects: This invention addresses the temperature requirements at each stage of the waste rubber and plastic pyrolysis process and the characteristics of high-quality product generation. By designing a flue gas swirl mixing chamber and flue gas internal and external flow guiding modules, combined with a one-stage internal heating pyrolysis spiral structure and an external heating module, the waste rubber and plastic are heated in an orderly manner during pyrolysis. The temperature in the pyrolysis zone is precisely controllable, which improves the oil yield. The high temperature in the conditioning zone reduces the oil content of the solid products, significantly increasing the added value of the products. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The images show a side view and a top view of the single-stage internal and external flow-diverting zone temperature-controlled waste rubber and plastic pyrolysis system according to an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of a single-stage internal heating pyrolysis spiral in this embodiment.

[0032] Figure 3 This is the temperature distribution at the outlet of the flue gas cyclone mixing chamber in this embodiment.

[0033] Figure 4 This is a schematic diagram of the flue gas internal and external flow guiding module in this embodiment.

[0034] Figure 5 This is a three-dimensional diagram of the internal and external flue gas guiding components in this embodiment.

[0035] Figure 6 This is a top view of the heat exchange pin distribution of the external heating module in this embodiment.

[0036] Figure 7 The temperature of each zone in the single-stage internal and external flow-guided zone temperature-controlled waste rubber and plastic pyrolysis system of this embodiment is set. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that, unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0039] like Figure 1 As shown, the one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis system includes: a dual-stage sealed feeding module 1, a one-stage internal heating pyrolysis spiral 2, a pyrolysis oil and gas outlet 3, a pyrolysis solid phase outlet 4, a high-temperature combustion furnace 5, a flue gas swirl mixing chamber 6, a flue gas internal and external flow-guided module 7, an internal-external heating flue gas connecting pipe 8, an external heating module 9, a flue gas circulation fan 10, a circulating flue gas module 11, a zoned temperature measurement module 12, and an integrated skid-mounted base 13.

[0040] The dual-stage sealed feeding module 1 consists of a small hopper 101, a horizontal feeding screw 102, and an inclined feeding double screw 103, achieving sealed feeding of materials and self-cleaning of the feed inlet; the one-stage internal heating pyrolysis screw 2 carries high-temperature flue gas internally and is equipped with screw blades of different pitches externally for internal heating and conveying of pyrolysis materials; the pyrolysis oil and gas outlet 3 is located in the middle of the pyrolysis device near the rear end, used to promptly discharge the high-temperature oil and gas generated by the pyrolysis of waste rubber and plastics; the pyrolysis solid phase outlet 4 is located at the rear end of the pyrolysis device, used to discharge the solid products generated by the pyrolysis of waste rubber and plastics; the high-temperature combustion furnace 5 consists of a burner 501, a high-temperature combustion section 502, and a high-temperature flue gas outlet 503, used to efficiently burn the non-condensable gas generated by pyrolysis to generate high-temperature flue gas; the flue gas swirl mixing chamber 6 is used to orderly mix the high-temperature flue gas generated by the high-temperature combustion furnace with the recirculated flue gas, and the mixed flue gas enters the one-stage internal heating pyrolysis screw; the flue gas internal and external flow guiding module 7 is located inside the one-stage internal heating pyrolysis screw. The system comprises a flow-guiding module with high-temperature flue gas flowing through the front section, internally and externally through the middle section, and externally through the rear section, achieving zoned temperature control of the internally heated pyrolysis spiral and increasing the temperature of the rear section of the pyrolysis spiral. An internal-external heating flue gas connecting pipe 8 connects the flue gas outlet of the single-stage internally heated pyrolysis spiral to the flue gas inlet of the external heating module. The external heating module 9 has flue gas flowing counter-currently to the material conveying direction, heating the material from the outside and reducing the exhaust temperature. A flue gas circulation fan 10, located at the external heating flue gas outlet of the external heating module 9, drives the flue gas to flow within the single-stage internally heated pyrolysis spiral 2 and the external heating module 9. A circulating flue gas module 11 controls the amount of recirculated flue gas and adjusts the temperature of the pyrolysis flue gas, achieving precise control of the waste rubber and plastic pyrolysis temperature. A zoned temperature measurement module 12 measures the pyrolysis temperature of materials in the preheating zone, pyrolysis zone, and conditioning zone. An integrated skid-mounted base 13 houses the single-stage internal and external flow-guiding zoned temperature control waste rubber and plastic pyrolysis system, facilitating in-plant assembly, debugging, and overall hoisting and transportation.

[0041] In order to achieve high-value utilization of waste rubber and plastic (waste tires) through pyrolysis, this embodiment addresses the temperature requirements at each stage of the waste tire pyrolysis process and the characteristics of high-quality product generation. By designing a flue gas swirl mixing chamber and flue gas internal and external flow guiding modules, combined with a one-stage internal heating pyrolysis spiral structure and an external heating module, the waste tires are heated in an orderly manner during pyrolysis. The temperature in the pyrolysis zone is precisely controllable, which improves the oil yield. The high temperature in the tempering zone reduces the oil content of the solid product pyrolysis carbon black, significantly increasing the added value of the product.

[0042] The pyrolysis of waste tires is carried out in a slightly negative pressure, oxygen-free environment. To achieve sealed feeding, the horizontal feeding screw 102 and the inclined feeding double screw 103 in the dual-stage sealed feeding module are arranged vertically. The horizontal feeding screw 102 is a shaftless screw with a screw length greater than 10 times the screw pitch. During the feeding process, the horizontal feeding screw 102 performs extrusion conveying, acting as a material seal. The material temperature at the inlet is low, while the pyrolysis oil and gas inside the pyrolysis device can easily adhere and clog at the material inlet. Therefore, the inclined feeding double screw 103 is designed with a self-cleaning function to prevent material blockage at the inlet.

[0043] To achieve the conveying and heating during the pyrolysis of waste tires, the one-stage internally heated pyrolysis spiral 2 consists of a central flue gas inlet 201, a flue gas outlet 202, a feed reverse spiral blade 203, a preheating zone spiral blade 204, a pyrolysis zone spiral blade 205, a conditioning zone spiral blade 206, a discharge reverse spiral blade 207, a conditioning zone flue gas side heat exchange nail 208, and end-support internal insulation 209. Figure 2 As shown. Due to the release of oil and gas during the pyrolysis of waste tires, the pyrolysis rate has reached 95% in the tempering zone, and the proportion of solid products is less than 40%. Therefore, the pitch of the spiral blade 204 in the preheating zone and the spiral blade 206 in the tempering zone gradually decreases, with the latter pitch being about half that of the former.

[0044] The internal heating pyrolysis spiral 1 carries high-temperature flue gas, which heats the spiral blades and then reheats the waste tire material. The spiral blades both transport and agitate the material and heat it; here, the spiral blades act like enhanced heat exchange fins, significantly increasing the heat exchange area. In the conditioning zone, the pitch of the spiral blades 206 decreases, increasing the heat exchange area. Combined with the enhanced heat transfer effect of the flue gas-side heat exchange pins, the spiral blade temperature also rises. This helps to increase the material temperature in the conditioning zone and reduce the oil content of the solid product, pyrolytic carbon black.

[0045] To reduce the consumption of non-condensable gases and improve combustion efficiency in the waste tire pyrolysis system, a high-temperature combustion furnace was designed to ensure the complete combustion of organic matter in the non-condensable gases at high temperatures. The high-temperature flue gas generated during combustion then enters the flue gas swirl mixing chamber 6, where it is orderly mixed with the recirculated flue gas. In the flue gas swirl mixing chamber 6, the recirculated flue gas (450~480℃) enters tangentially at 602, while the high-temperature flue gas (1600~1800℃) generated by the high-temperature combustion furnace enters from the center at 601. The swirling and mixed flue gas exits from the center at 603. The flue gas temperature is high at the center and low at the periphery, as shown in the diagram. Figure 3 This creates a flow field structure where low-temperature flue gas envelops high-temperature flue gas, reducing heat loss and facilitating the orderly utilization of flue gas in subsequent internal and external flue gas guiding modules.

[0046] To further increase the material temperature in the conditioning zone while ensuring controllable material temperature in the pyrolysis zone, a flue gas internal and external flow guiding module 7 was designed. This module includes a front flue pipe 701, a front central flue gas zone 702, a front outer flue gas zone 703, a middle flue gas internal and external flow guiding component 704, a rear flue pipe 705, a rear outer flue gas zone 706, a rear central flue gas zone 707, and rear flue pipe internal insulation 708. (See...) Figure 4 Through the flue gas internal and external flow guiding module, the flue gas exiting the flue gas swirl mixing chamber 6 enters the front central flue gas zone 702 and the front outer flue gas zone 703 respectively. Because the temperature of the flue gas at the center after swirl mixing is high, the flue gas temperature in the front central flue gas zone 702 is higher than that in the front outer flue gas zone 703. For example... Figure 4 and Figure 5 As shown, the end of the front central flue gas zone 702 is closed and connected to the interior of the middle flue gas inner and outer guide component 704. After passing through the middle flue gas inner and outer guide component 704, the light blue arrow indicates that the high-temperature flue gas in the front central flue gas zone 702 flows through the interior of the middle flue gas inner and outer guide component 704 to the rear outer flue gas zone 706. The dark blue arrow indicates that the flue gas in the front outer flue gas zone 703, after heat exchange, flows through the outside of the middle flue gas inner and outer guide component 704 to the rear central flue gas zone 707. In this way, the high-temperature flue gas in the front central flue gas zone 702 is transported to the rear outer flue gas zone 706, thereby increasing the temperature of the rear section of the pyrolysis spiral.

[0047] Since the pyrolysis temperature of waste tires is between 420 and 450°C, the material needs to rise from ambient temperature to the pyrolysis temperature to move from the preheating zone to the pyrolysis zone. However, the amount of solid products decreases after the pyrolysis oil and gas are released. The material in the conditioning zone only needs to be heated by 100 to 150°C. Therefore, the flue gas volume in the outer flue gas zone 703 is five times that of the central flue gas zone 702 to ensure the pyrolysis temperature of the material in the pyrolysis zone. Because the flue gas volume in the central flue gas zone 702 is small, the flue gas volume in the outer flue gas zone 706 is also small. To increase the flow rate in the outer flue gas zone 706, the diameter of the rear flue pipe 705 is increased. Simultaneously, an internal insulation 708 is installed in the rear flue pipe to reduce the heat transfer from the outer flue gas zone 706 to the central flue gas zone 707, thereby improving the heating effect of the flue gas in the internal and external flue gas guiding modules. To further achieve the distribution of flue gas volume between the outer flue gas zone and the central flue gas zone of the inner and outer diversion modules, a butterfly valve can be installed at the inlet of the front flue pipe 701, and the flue gas volume entering the central flue gas zone 702 can be adjusted by adjusting the valve opening.

[0048] By setting up flue gas internal and external flow guiding modules, the temperature of the preheating zone, pyrolysis zone and conditioning zone can be precisely controlled. Generally, in order to increase the temperature of the conditioning zone, the temperature of the preheating zone and pyrolysis zone will inevitably be increased, resulting in the inability to accurately control the pyrolysis temperature. Excessively high pyrolysis temperature will reduce the oil yield, increase the heavy components in the pyrolysis oil, and reduce the oil quality.

[0049] To improve the heat utilization of flue gas, an external heating module 9 is installed. This module includes an externally heated flue gas inlet 901, guide vanes 902, heat exchange nails in the conditioning zone 903, heat exchange nails in the pyrolysis zone 904, heat exchange nails in the preheating zone 905, an externally heated flue gas outlet 906, and external insulation 907. Since the pyrolysis material is mainly located in the lower part of the pyrolysis unit, the heat exchange nails are also arranged in the lower part of the pyrolysis unit. After the pyrolysis zone, the solid products decrease, and the heat exchange nails in the pyrolysis zone have the largest circumferential proportion, while those in the conditioning zone have the fewest. Figure 6 The image shows a top view of the heat exchange pin distribution of the external heating module. The arrangement of the heat exchange pins enhances heat transfer on the flue gas side and improves the utilization rate of flue gas heat.

[0050] To reduce exhaust gas temperature and simplify the flue gas pipeline, the flue gas from the external heating module flows in the opposite direction to the material conveying direction. The flue gas discharged from the center of the one-stage internal heating pyrolysis spiral 2 enters the external heating module from the external heating flue gas inlet of the conditioning zone.

[0051] Furthermore, to improve the heat utilization of the flue gas, the pyrolysis temperature is controlled by adjusting the flue gas volume of the pyrolysis system. A circulating flue gas module is installed, which includes a recirculation flue pipe 1101, a recirculation flue gas flow meter 1102, a recirculation regulating valve 1103, an exhaust flue pipe 1104, an exhaust flue gas flow meter 1105, and an exhaust flue gas regulating valve 1106. The total flue gas volume of the pyrolysis system can be calculated based on the recirculation flue gas flow rate and the exhaust flue gas flow rate. The recirculation flue gas volume can be controlled by adjusting the exhaust flue gas regulating valve and the recirculation regulating valve.

[0052] The zoned temperature measurement module is divided into three measurement points: preheating zone 1201, pyrolysis zone 1202, and conditioning zone 1203. It can display the pyrolysis temperature of materials in the preheating, pyrolysis, and conditioning zones. The temperatures of each measurement point in this embodiment are shown below. Figure 7 This provides data for the regulation of the circulating flue gas module.

[0053] Increasing the system flue gas volume can increase the flue gas velocity, increase the heat transfer coefficient on the flue gas side, reduce the exhaust gas temperature, and reduce system energy consumption.

[0054] This embodiment also provides a one-stage internal and external flow-guided zoned temperature-controlled waste tire pyrolysis method, including the following steps: S1, the waste tire material in the small hopper is conveyed to the one-stage internal heating pyrolysis spiral through the double-stage sealed feeding module; S2, the material is conveyed by a one-stage internal heating and pyrolysis screw conveyor and passes through the preheating zone, pyrolysis zone and conditioning zone in sequence, and the material is heated and pyrolyzed; S3, the material temperature gradually increases from the preheating zone to the conditioning zone. Due to the design of the flue gas internal and external flow guiding module, the internal heating flue gas temperature first decreases and then increases. S4, adjust the burner load and recirculated flue gas volume according to the material quantity, thereby controlling the pyrolysis temperature of different zones; S5, the oil and gas generated from the pyrolysis of waste tires are discharged in a timely manner from the pyrolysis oil and gas outlet at the rear end of the middle of the pyrolysis unit to avoid prolonged residence in the unit and subsequent reforming reaction. S6, after most of the oil and gas are discharged, the temperature of the conditioning zone is increased so that the solid products are completely discharged from the pyrolysis solid phase outlet.

[0055] To improve the quality of waste tire pyrolysis products, the setting of the flue gas internal and external flow guiding module in step S3 can significantly increase the pyrolysis temperature of the conditioning zone, improve the physical properties of solid products, and at the same time avoid the increase of heavy products (tar, rubber, asphalt, etc.) caused by excessively high temperature in the pyrolysis zone, thus achieving zoned temperature control.

[0056] To improve the quality of waste tire pyrolysis products, in step S5, the outlet position of the pyrolysis oil and gas can be adjusted according to the pyrolysis characteristics of the material. When a large amount of pyrolysis oil and gas is released, it should be discharged in time to avoid the oil and gas from heating up and undergoing a reforming reaction, which would degrade the oil quality and increase energy consumption.

[0057] In summary, the system and method of this embodiment have the advantages of simple structure, precise temperature control by partition, flexible system adjustment, and high quality of pyrolysis products.

[0058] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis system, characterized in that, include: A dual-stage sealed feeding module is installed at the feed inlet of the one-stage internal heating pyrolysis spiral to achieve sealed feeding of materials and self-cleaning of the feed inlet; A one-stage internal heating pyrolysis spiral is set with a preheating zone, a pyrolysis zone, and a conditioning zone along the material conveying direction. High-temperature flue gas flows inside, and spiral blades with different pitches are set in each zone on the outside for internal heating and conveying of pyrolysis materials. The pyrolysis oil and gas outlet is located in the middle of the rear end of the one-stage internal heating pyrolysis spiral, and is used to discharge the high-temperature oil and gas generated by the pyrolysis of waste rubber and plastic. The pyrolysis solid phase discharge port is located at the rear end of the one-stage internal heating pyrolysis spiral and is used to discharge the solid products generated by the pyrolysis of waste rubber and plastic. A high-temperature combustion furnace is used to burn the non-condensable gases produced by pyrolysis to generate high-temperature flue gas; The flue gas swirl mixing chamber is used to orderly mix the high-temperature flue gas generated by the high-temperature combustion furnace with the recirculated flue gas output from the external heating module. After mixing, the flue gas enters the one-stage internal heating pyrolysis spiral. The flue gas internal and external flow guiding module is set inside the one-stage internal heating pyrolysis spiral. High-temperature flue gas flows inside the front section and through the middle flue gas internal and external flow guiding component, high-temperature flue gas flows outside the rear section, realizing zoned temperature control of the one-stage internal heating pyrolysis spiral and improving the temperature of the rear section of the pyrolysis spiral. The internal-external heating flue gas connection pipe is used to connect the flue gas outlet of the one-stage internal heating pyrolysis spiral and the flue gas inlet of the external heating module; The external heating module is installed outside the one-stage internal heating pyrolysis spiral. Its flue gas flows in the opposite direction to the material conveying direction, heating the material from the outside and reducing the exhaust temperature. Flue gas recirculation fan is used to drive flue gas to flow within the one-stage internal heating pyrolysis spiral and external heating module; The circulating flue gas module is used for controlling the amount of recirculated flue gas and regulating the temperature of pyrolysis flue gas, so as to achieve precise control of the pyrolysis temperature of waste rubber and plastic. The zone temperature measurement module is used to measure the pyrolysis temperature of materials in the preheating zone, pyrolysis zone, and conditioning zone.

2. The one-stage internal and external flow-diverting zoned temperature-controlled waste rubber and plastic pyrolysis system according to claim 1, characterized in that, The dual-stage sealed feeding module includes a small hopper, a horizontal feeding screw, and an inclined feeding twin screw; The horizontal feeding screw and the inclined feeding double screw are arranged vertically. The horizontal feeding screw is a shaftless screw with a screw length greater than 10 times the screw pitch. During the feeding process, the horizontal feeding screw performs extrusion and conveying, and acts as a material seal. The inclined feeding double screw has a self-cleaning function to prevent the feed port from being blocked.

3. The one-stage internal and external flow-diverting zoned temperature-controlled waste rubber and plastic pyrolysis system according to claim 1, characterized in that, The single-stage internal heating pyrolysis spiral includes, in sequence along the pyrolysis material conveying direction, a feeding reverse spiral blade, a preheating zone spiral blade, a pyrolysis zone spiral blade, a conditioning zone spiral blade, and a discharging reverse spiral blade; The pitch of the spiral blades in the preheating zone gradually decreases from the spiral blades in the quenching and tempering zone, and the pitch of the spiral blades in the quenching and tempering zone is 50% to 60% of the pitch of the spiral blades in the preheating zone.

4. The one-stage internal and external flow-diverting zoned temperature-controlled waste rubber and plastic pyrolysis system according to claim 3, characterized in that, Heat exchange nails are installed on the flue gas side of the quenching zone to increase the heating temperature of the spiral blades in the quenching zone.

5. The one-stage internal and external flow-diverting zoned temperature-controlled waste rubber and plastic pyrolysis system according to claim 1, characterized in that, In the flue gas swirl mixing chamber, the high-temperature flue gas of 1600~1800℃ generated by the high-temperature combustion furnace enters from the center, while the recirculated flue gas of 450~480℃ enters tangentially. After swirl mixing, the flue gas has a high temperature at the center and a low temperature at the periphery.

6. The one-stage internal and external flow-diverting zoned temperature-controlled waste rubber and plastic pyrolysis system according to claim 1, characterized in that, The flue gas internal and external flow guiding module includes a front flue pipe, a front central flue gas zone, a front outer flue gas zone, a middle flue gas internal and external flow guiding component, a rear flue pipe, a rear outer flue gas zone, a rear central flue gas zone, and internal insulation of the rear flue pipe. Through the flue gas internal and external flow guiding module, the flue gas coming out of the flue gas swirl mixing chamber enters the front central flue gas zone and the front outer flue gas zone respectively. Since the temperature of the flue gas center after swirl mixing is high, the flue gas temperature in the front central flue gas zone is higher than that in the front outer flue gas zone. After passing through the middle flue gas internal and external flow guiding component, the high-temperature flue gas in the front central flue gas zone is transported to the rear outer flue gas zone, thereby increasing the temperature of the rear section of the pyrolysis spiral.

7. The one-stage internal and external flow-diverting zoned temperature-controlled waste rubber and plastic pyrolysis system according to claim 1, characterized in that, The external heating module includes an external heating flue gas inlet, guide vanes, heat exchange pins in the conditioning zone, heat exchange pins in the pyrolysis zone, heat exchange pins in the preheating zone, an external heating flue gas outlet, and external insulation; The heat exchange nails in the quenching zone, pyrolysis zone, and preheating zone are arranged at the lower part of the outer heating module cylinder wall.

8. The one-stage internal and external flow-diverting zoned temperature-controlled waste rubber and plastic pyrolysis system according to claim 1, characterized in that, The recirculating flue gas module includes a recirculating flue pipe, a recirculating flue gas flow meter, a recirculating regulating valve, an exhaust flue pipe, an exhaust flue gas flow meter, and an exhaust flue gas regulating valve; One end of the recirculation pipe is connected to the outlet of the flue gas recirculation fan, and the other end is connected to the flue gas swirl mixing chamber; The total flue gas volume of the pyrolysis system is calculated based on the recirculated flue gas flow rate and the exhaust flue gas flow rate. The recirculated flue gas volume is then controlled by adjusting the exhaust flue gas regulating valve and the recirculation regulating valve.

9. A one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis method, characterized in that, The single-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis system according to any one of claims 1 to 8 includes the following steps: (1) Waste rubber and plastic materials are conveyed to a single-stage internal heating pyrolysis spiral through a double-stage sealed feeding module; (2) The material is conveyed by a one-stage internal heating and pyrolysis screw conveyor and passes through the preheating zone, pyrolysis zone and conditioning zone in sequence, and the material is heated and pyrolyzed; (3) The material temperature gradually increases from the preheating zone to the conditioning zone. By setting up internal and external flue gas guiding modules, the internal heating flue gas temperature first decreases and then increases. (4) Adjust the burner load and recirculated flue gas volume of the high-temperature combustion furnace according to the material quantity, thereby controlling the pyrolysis temperature of different zones; (5) The oil and gas generated from the pyrolysis of waste rubber and plastic should be discharged from the pyrolysis oil and gas outlet in a timely manner to avoid secondary reactions caused by prolonged residence; (6) After most of the oil and gas are discharged, the temperature of the conditioning zone is increased so that the solid products are completely discharged from the pyrolysis solid outlet.

10. The one-stage internal and external flow-guided zoned temperature-controlled waste rubber and plastic pyrolysis method according to claim 9, characterized in that, In step (3), the pyrolysis temperature of the conditioning zone is increased by setting the flue gas internal and external flow guiding module, which improves the physical properties of the solid products and avoids the increase of heavy products of pyrolysis oil and gas caused by excessively high temperature in the pyrolysis zone, thus achieving zoned temperature control.

Images