A continuous mixed waste plastic harmless pyrolysis treatment system and treatment method

Abstract

The invention discloses a continuous harmless pyrolysis disposal system and a disposal method for mixed waste plastics, and relates to the technical field of plastic recycling and utilization, comprising: a pyrolysis reactor, wherein a spiral pusher is arranged in the pyrolysis chamber of the pyrolysis reactor, and along the pushing direction of the spiral pusher, the pyrolysis chamber of the pyrolysis reactor is divided into a plurality of heating sections, and the heating temperatures of different heating sections respectively correspond to the pyrolysis temperatures required for pyrolyzing plastics of different materials to produce oil and gas, and the temperatures of the plurality of heating sections are successively increased, and waste plastics of different materials are pyrolyzed in different heating sections respectively; in the invention, the mixed waste plastics are disposed of by using heating sections providing different pyrolysis temperatures in the same pyrolysis reactor, and plastics of different materials in the mixed waste plastics are pyrolyzed in the heating sections corresponding to the pyrolysis temperatures, thereby realizing the pyrolysis of the mixed waste plastics in the same pyrolysis reactor, saving the pre-sorting link, and greatly improving the disposal efficiency of the waste plastics.

Description

Technical Field

[0001] The invention relates to the technical field of plastic recycling, and in particular to a continuous mixed type harmless pyrolysis disposal system and a disposal method for waste plastics. Background Art

[0002] With the continuous development of society and economy, various plastic products are increasingly widely used in various fields such as industry, agriculture, national defense, medical care and health, as well as in people's daily lives; however, a large amount of waste plastics are also generated, causing serious environmental pollution.

[0003] With the popularization of the concept of waste recycling, plastic pyrolysis technology has become the main means of recycling waste plastics. For example, the invention patent with application number "201410676801.X" and name "Waste Plastic Pyrolysis Internal Heating Continuous Production of Fuel Oil System" discloses a waste plastic pyrolysis system. During the plastic pyrolysis process, the plastics need to be sorted first, classified according to the material of the plastics, and the same type of plastics are placed in the pyrolysis reactor. The temperature in the pyrolysis reactor is controlled to correspond to the pyrolysis temperature of this type of plastics, thereby achieving pyrolysis of the plastics. However, the early sorting step will extend the overall disposal time of the plastics and greatly reduce the disposal efficiency of the plastics.

[0004] Therefore, people are in urgent need of a continuous mixed waste plastic harmless pyrolysis treatment system with high plastic treatment efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a continuous harmless pyrolysis disposal system and method for mixed waste plastics to solve the problems existing in the above-mentioned prior art. Several heating sections are set in the same pyrolysis reactor to achieve pyrolysis of mixed waste plastics in the same pyrolysis reactor, saving the pre-sorting link and greatly improving the disposal efficiency of waste plastics.

[0006] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a continuous mixed waste plastic harmless pyrolysis disposal system, comprising a pyrolysis reactor, wherein a spiral pusher for conveying plastic is arranged in the pyrolysis chamber of the pyrolysis reactor, and along the pushing direction of the spiral pusher, the pyrolysis chamber of the pyrolysis reactor is divided into a plurality of heating sections, and the heating temperatures of different heating sections respectively correspond to the pyrolysis temperatures required for pyrolysis of plastics of different materials to produce oil and gas, and along the pushing direction of the spiral pusher, the temperatures of the plurality of heating sections increase successively, and waste plastics of different materials complete pyrolysis in different heating sections respectively.

[0007] Preferably, the pyrolysis reactor includes the spiral pusher, the heat transfer inner cylinder with heat transfer characteristics and the heat insulation outer cylinder for heat preservation which are sequentially arranged from the inside to the outside, the inner cavity of the heat transfer inner cylinder is the pyrolysis chamber, and a heating coil installation cavity is formed between the heat insulation outer cylinder and the heat transfer inner cylinder, and the heating coil installation cavity includes a plurality of heating segments arranged corresponding to the heating sections, and the plurality of heating segments are all provided with electric heating coils.

[0008] Preferably, the continuous mixed waste plastic harmless pyrolysis disposal system also includes a feeding unit, which includes a feeder, a screw feeder and a conveying mechanism for conveying plastic to the feeder, the discharge port of the feeder is connected to the feed port of the screw feeder, the discharge port of the screw feeder is connected to the heat transfer inner cylinder, and the screw feeder is provided with a heating module for heating the plastic to a molten state.

[0009] Preferably, the conveying mechanism includes a first conveyor, a briquetting machine for pressing plastic into blocks, and a second conveyor, wherein one end of the first conveyor is located above the feed port of the briquetting machine, and the other end is arranged on the ground, and one end of the second conveyor is located below the discharge port of the briquetting machine, and the other end is located above the feed port of the dropper.

[0010] Preferably, the continuous mixed waste plastic harmless pyrolysis disposal system also includes a gas product processing unit, which includes a catalytic tower for removing impurity components, a plurality of oil and gas condensers for separating oil and gas, and a non-condensable combustible gas collection system for collecting non-condensable combustible gas, which are connected in sequence. The air inlet of the catalytic tower is connected to the outlet of the heat transfer inner cylinder.

[0011] Preferably, the non-condensable combustible gas collection system includes a plurality of purification tanks for storing water or reactants and storage equipment for storing non-condensable combustible gas, the plurality of purification tanks are connected in sequence, and the end of the purification tank is connected to the storage equipment, the purification tank is provided with an air inlet pipe and an air outlet pipe connected to the air outlet of the oil-gas condenser, one end of the air inlet pipe away from the oil-gas condenser extends into the cavity and is submerged in water or reactants, and the air outlet pipe is arranged on the top of the purification tank.

[0012] Preferably, the continuous mixed waste plastic harmless pyrolysis disposal system also includes a solid product processing unit, which includes a plurality of water-cooled spiral slag dischargers and a receiving silo connected in sequence, and the feed port of the first water-cooled spiral slag discharger is connected to the discharge port of the pyrolysis chamber.

[0013] Preferably, several of the water-cooled spiral slag dischargers are arranged at an angle, and the discharge port of the water-cooled spiral slag discharger is higher than the feed port, and the feed port of the rear water-cooled spiral slag discharger is located below the discharge port of the front water-cooled spiral slag discharger.

[0014] Preferably, a buffer is provided at the outlet of the heat transfer inner cylinder, and the bottom of the buffer is connected to the water-cooled spiral slag discharger through a valve.

[0015] The present invention also provides a method for treating a continuous mixed type waste plastic harmless pyrolysis treatment system, comprising the following steps:

[0016] S1: The mixed waste plastics are conveyed to the briquetting machine by the first conveyor for compaction, and the air contained therein is discharged, and then conveyed to the blanking device by the second conveyor for unloading;

[0017] S2: Blocky mixed waste plastics enter the screw feeder and are transported to the heat transfer inner cylinder. During the transportation process, they are heated to a molten state and some moisture is removed.

[0018] S3: The molten mixed waste plastics move in the heat transfer inner cylinder and pass through the heating areas formed by several heating sections in the heat transfer inner cylinder in sequence. Plastics of different materials are pyrolyzed in different heating areas to generate oil, gas and carbon slag.

[0019] S4: After the oil and gas pass through the catalytic tower to remove impurities, they enter the oil and gas condenser, where the oil and water are condensed and collected, and the non-condensable combustible gas is processed in the purification tank and then collected by the storage equipment; the carbon slag falls into the cold spiral slag discharger and is continuously cooled during the transportation process until it is collected by the receiving silo.

[0020] Compared with the prior art, the present invention has achieved the following technical effects:

[0021] 1. In the present invention, mixed waste plastics are disposed of by using heating sections providing different pyrolysis temperatures in the same pyrolysis reactor. Plastics of different materials in the mixed waste plastics will be pyrolyzed in the heating sections corresponding to the pyrolysis temperatures, thereby realizing the pyrolysis of mixed waste plastics in the same pyrolysis reactor, saving the pre-sorting link, and greatly improving the disposal efficiency of waste plastics. Moreover, in the same pyrolysis reactor, the rear high-temperature heating section will provide certain heat support to the front low-temperature heating section, which can relatively reduce the power of the heating component of the front low-temperature heating section, thereby achieving the purpose of energy saving. In addition, the plastic will have a certain temperature after passing through the front low-temperature heating section, which has a preheating effect, thereby further improving the disposal efficiency of the plastic. In addition, setting different heating sections in the same pyrolysis reactor can reduce the space occupation and cost of the overall device compared to a pyrolysis reactor in which different pyrolysis temperatures are continuously set.

[0022] 2. In the present invention, the waste plastics are melted before entering the pyrolysis reactor, which can effectively remove most of the water contained in the waste plastics, avoiding the problem that a large amount of water contained in the plastics absorbs too much heat during the subsequent pyrolysis process, increases the power consumption of the device, and prolongs the plastic disposal time.

[0023] 3. In the present invention, the air contained in the expanded plastic is discharged through the compaction effect of the briquetting machine, which greatly reduces the oxygen content and water content in the subsequent pyrolysis process, thereby greatly reducing the generation of dioxin harmful gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 It is a structural schematic diagram of the continuous mixed waste plastic harmless pyrolysis disposal system of the present invention;

[0026] Among them, 1. the first conveyor; 2. the briquetting machine; 3. the second conveyor; 4. the feeder; 5. the screw feeder; 6. the pyrolysis reactor; 7. the first heating section; 8. the second heating section; 9. the third heating section; 10. the buffer; 11. the catalytic tower; 12. the oil-gas condenser; 13. the water collecting tank; 14. the oil storage tank; 15. the purification tank; 16. the storage equipment; 17. the water-cooled screw slag discharger; 18. the cooling water inlet; 19. the cooling water outlet; 20. the receiving silo; 21. the ton bag. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The purpose of the present invention is to provide a continuous harmless pyrolysis disposal system and method for mixed waste plastics to solve the problems existing in the prior art. Several heating sections are set in the same pyrolysis reactor to achieve pyrolysis of mixed waste plastics in the same pyrolysis reactor, saving the pre-sorting link and greatly improving the disposal efficiency of waste plastics.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Please refer to Figure 1 As shown, a continuous mixed waste plastic harmless pyrolysis disposal system is provided, including a pyrolysis reactor 6, wherein a spiral pusher for conveying plastic is arranged in the pyrolysis chamber of the pyrolysis reactor 6, and along the pushing direction of the spiral pusher, the pyrolysis chamber of the pyrolysis reactor 6 is divided into a plurality of heating sections, and the lengths of different heating sections are the same, and the heating temperatures of different heating sections correspond to the pyrolysis temperatures required for pyrolysis of plastics of different materials to produce oil and gas, and along the pushing direction of the spiral pusher, the temperatures of the plurality of heating sections are successively increased, and waste plastics of different materials are pyrolyzed in different heating sections respectively, and the pushing speed of the spiral pusher and the length of the heating section can be determined by the pyrolysis time of plastics of different materials, and on the basis of the same length of different heating sections, the pushing speed of the spiral pusher should be calculated according to the longest pyrolysis time of plastics of different materials, and the device is arranged in the same pyrolysis reactor 6 Mixed waste plastics are disposed of by using heating sections that provide different pyrolysis temperatures. Plastics of different materials in the mixed waste plastics will be pyrolyzed in the heating sections with corresponding pyrolysis temperatures, thereby realizing the pyrolysis of mixed waste plastics in the same pyrolysis reactor 6, saving the pre-sorting link, and greatly improving the disposal efficiency of waste plastics. Moreover, in the same pyrolysis reactor 6, the high-temperature heating section at the rear will provide a certain amount of heat support to the low-temperature heating section at the front, which can relatively reduce the power of the heating component of the low-temperature heating section at the front, thereby achieving the purpose of saving energy. In addition, the plastic will have a certain temperature after passing through the low-temperature heating section at the front, which has a preheating effect, thereby further improving the disposal efficiency of the plastic. In addition, setting different heating sections in the same pyrolysis reactor 6 can reduce the space occupancy and cost of the overall device compared to the pyrolysis reactor 6 with continuously set different pyrolysis temperatures.

[0031] In this embodiment, three heating sections are provided. The temperature of the first heating section 7 is controlled in the range of 130°C to 230°C. At this temperature, low-boiling-point molten waste plastics undergo thermal cracking reactions, such as methacrylic resin, polyvinyl chloride, polyoxymethylene, polyvinylidene chloride, etc.; then, the molten waste plastics that have not yet been pyrolyzed enter the second heating section 8, and the temperature is controlled in the range of 170°C to 320°C. At this temperature, medium-boiling-point molten waste plastics undergo thermal cracking reactions, such as polypropylene, PET, PC, PS, PP, polyethylene, polystyrene, polyvinylidene chloride, etc. Vinylidene fluoride, etc.; the remaining molten waste plastics enter the third heating section 9, and the temperature is controlled in the range of 280℃~430℃. At this temperature, the molten waste plastics with high boiling point undergo thermal cracking reaction, such as nylon 6, polypropylene, polystyrene, ABD, alloy plastics, HD and other high-density waste plastics. The reason for processing plastics of the same material in different heating sections is that even if they are plastics of the same name, there are slight differences in the internal additives during actual production, that is, they are essentially different, so they need to be processed in different heating sections.

[0032] The pyrolysis reactor 6 includes a spiral pusher that is sequentially arranged from the inside to the outside, a heat transfer inner cylinder with heat transfer characteristics, and a heat insulation outer cylinder for insulation. The heat transfer inner cylinder can be made of cast iron. The heat insulation outer cylinder includes an outer shell and an inner layer of insulation material. The outer shell can be made of Q235 steel plate and reinforced channel steel. The insulation material can be divided into an inner layer of insulation material and an outer layer of insulation material. The inner layer is Class A non-combustible refractory rock wool, and the outer layer material is refractory cement. The inner cavity of the heat transfer inner cylinder is a pyrolysis cavity. A heating coil installation cavity is formed between the heat insulation outer cylinder and the heat transfer inner cylinder. The heating coil installation cavity includes several heating sections arranged corresponding to the heating sections. Several heating sections are all provided with electric heating coils. The electric heating coils are used to provide heat to the heating sections. The electric heating coils in adjacent heating sections are arranged at intervals.

[0033] The continuous mixed waste plastic harmless pyrolysis disposal system also includes a feeding unit, which includes a feeder 4, a screw feeder 5 and a conveying mechanism for conveying plastic to the feeder 4. The discharge port of the feeder 4 is sealed and connected with the feed port of the screw feeder 5, and the discharge port of the screw feeder 5 is sealed and connected with the heat transfer inner cylinder. The screw feeder 5 conveys the plastic to the heat transfer inner cylinder through a bolt conveying rod. The screw feeder 5 is provided with a heating module for heating the plastic to a molten state. The heating module can select an electric heating coil. The heating module is used to melt the waste plastic before it enters the pyrolysis reactor 6, which can effectively remove most of the water contained in the waste plastic, and avoid the problem that a large amount of water contained in the plastic absorbs too much heat in the subsequent pyrolysis process, increases the power consumption of the device and prolongs the plastic disposal time. The heating rate of the heating module is set according to the composition of the waste plastic and its own thermal melting point. The feeding rate of the screw feeder 5 is controlled at 5-8 kg / min.

[0034] The conveying mechanism includes a first conveyor 1, a briquetting machine 2 for pressing plastic into blocks, and a second conveyor 3. Both the first conveyor 1 and the second conveyor 3 can be belt conveyors. One end of the first conveyor 1 is located above the feed port of the briquetting machine 2, and the other end is arranged on the ground. One end of the second conveyor 3 is located below the discharge port of the briquetting machine 2, and the other end is located above the feed port of the dropper 4. Through the compaction effect of the briquetting machine 2, the air contained in the plastic in the expanded state is discharged, which greatly reduces the oxygen content and water content in the subsequent pyrolysis process, thereby greatly reducing the generation of dioxin harmful gases.

[0035] The continuous mixed waste plastic harmless pyrolysis disposal system also includes a gas product processing unit, which includes a catalytic tower 11 for removing impurity components, a plurality of oil and gas condensers 12 for separating oil and gas, and a non-condensable combustible gas collection system for collecting non-condensable combustible gas, which are connected in sequence. The catalytic tower 11 mainly uses catalytic combustion to remove impurity components. The air inlet of the catalytic tower 11 is connected to the discharge port of the heat transfer inner cylinder. The oil and gas condenser 12 is a double-cylinder structure with a water-cooling pipe coiled between the two cylinders. A condensed water outlet and a condensed oil outlet are provided on the inner cylinder. The different densities of oil and water are used to realize the separate discharge of condensed water and condensed oil. The condensed water outlet is connected to a water collecting tank 13 for collection, and the condensed oil outlet is connected to an oil storage tank 14 for collection.

[0036] Four oil and gas condensers 12 are arranged in this device. The oil and gas discharged from the catalytic tower 11 first enter the first group of condensers to exchange heat with cooling water. The low melting point oil and gas in the oil and gas are condensed into heavy pyrolysis oil and flow into the oil storage tank 14. Part of the water vapor in the oil and gas is condensed into water and flows into the water collecting tank 13. The remaining oil and gas are discharged into the second group of condensers through the exhaust port at the upper end of the first group of condensers for condensation. Then the sub-heavy pyrolysis oil and water distilled out flow into the oil storage tank 14 and the water collecting tank 13, respectively. By analogy, the medium pyrolysis oil and water distilled out from the third group of condensers flow into the oil storage tank 14 and the water collecting tank 13, respectively. The light pyrolysis oil and water distilled out from the fourth group of condensers flow into the oil storage tank 14 and the water collecting tank 13, respectively.

[0037] The non-condensable combustible gas collection system includes a plurality of purification tanks 15 for storing water or reactants and a storage device 16 for storing non-condensable combustible gas. The plurality of purification tanks 15 are connected in sequence, and the terminal purification tank 15 is connected to the storage device 16. The first purification tank 15 is provided with an air inlet pipe and an air outlet pipe connected to the air outlet of the oil-gas condenser 12. The air inlet pipe of the rear purification tank 15 is connected to the air outlet of the oil-gas condenser 12 through the front purification tank 15. The end of the air inlet pipe away from the oil-gas condenser 12 extends into the cavity and is submerged in water or reactants. The air outlet pipe is provided on the top of the purification tank 15. In this device, two purification tanks 15 for containing water and a purification tank 15 for containing reactants for removing solidified silicon are arranged in sequence. Water is used to remove impurities and chlorine in the non-condensable combustible gas, and the system pressure is maintained in the range of 0.07MPa to 0.09MPa, and the solidified silicon is removed by reactants.

[0038] The storage device 16 may be a plurality of groups of air compressors and gas storage tanks, and the air compressors may be used to compress the non-condensable combustible gas and then store it in the gas storage tanks.

[0039] The continuous mixed waste plastic harmless pyrolysis disposal system also includes a solid product processing unit, which includes a plurality of water-cooled spiral slag dischargers 17 and a receiving silo 20 connected in sequence. The feed port of the first water-cooled spiral slag discharger 17 is connected to the discharge port of the pyrolysis chamber. The carbon slag is cooled by the multi-stage water-cooled spiral slag discharger 17 and then transported to the receiving silo 20 for storage.

[0040] The receiving silo 20 includes a cylindrical box body at the upper end and a bell-shaped box body at the lower end. The large diameter end of the bell-shaped box body is connected to one end of the cylindrical box body, and the two have the same diameter. A valve is provided at the lower end of the bell-shaped box body. A ton bag 21 for transporting carbon slag can be provided at the valve port away from the bell-shaped box body.

[0041] A cooling water circulation pipe can be coiled outside the cylindrical box to cool the carbon slag inside. Several water-cooled spiral slag dischargers 17 and the cooling water circulation pipes outside the cylindrical box can be interconnected to form a cold water circulation system. The first water-cooled spiral slag discharger 17 is provided with a cooling water inlet 18, and the cylindrical box body is provided with a cooling water outlet 19. The cold water circulation order is that the cold water flowing out of the cold water tank passes through several water-cooled spiral slag dischargers 17 and the cylindrical box body in turn, and flows out from the cooling water outlet 19 provided on the cylindrical box body, and flows back to the cold water tank through the refrigeration equipment.

[0042] In order to save space, several water-cooled spiral slag dischargers 17 are arranged at an angle, and the discharge port of the water-cooled spiral slag discharger 17 is higher than the feed port, and the feed port of the rear water-cooled spiral slag discharger 17 is located below the discharge port of the front water-cooled spiral slag discharger 17.

[0043] A buffer 10 is provided at the outlet of the heat transfer inner cylinder, and the bottom of the buffer 10 is connected to the water-cooled spiral slag discharger 17 through a valve, and the flow rate of carbon slag flowing into the water-cooled spiral slag discharger 17 can be controlled by the valve.

[0044] The present invention also provides a method for treating a continuous mixed type waste plastic harmless pyrolysis treatment system, comprising the following steps:

[0045] S1: The mixed waste plastics are conveyed to the briquetting machine 2 by the first conveyor 1 for compaction, and the air contained therein is discharged, and then conveyed to the blanking device 4 by the second conveyor 3 for unloading;

[0046] S2: The bulk mixed waste plastics enter the screw feeder 5 and are transported to the heat transfer inner cylinder. During the transportation process, the bulk mixed waste plastics are heated to a molten state by the heating module to remove part of the moisture in the mixed waste plastics.

[0047] S3: The molten mixed waste plastics are controlled to move in the heat transfer inner cylinder by a screw pusher, and pass through the heating areas formed by the electric heating coils of several heating sections in the heat transfer inner cylinder in turn. Plastics of different materials are pyrolyzed in different heating areas to generate oil gas and carbon slag. When the heat transfer inner cylinder is initially fed, the running speed of the screw pusher can be slightly increased to increase the stirring and dispersion of the molten mixed waste plastics in the heat transfer inner cylinder, thereby avoiding the problem that the molten mixed waste plastics do not absorb enough heat to reach the pyrolysis temperature when the temperature in the heat transfer inner cylinder has not reached the specified temperature during the initial feeding. For example, the speed can be set to 80-130r / min initially, and 80-120r / min after the subsequent temperature reaches the specified temperature.

[0048] S4: After the oil and gas pass through the catalytic tower 11 to remove impurity components, they enter the oil and gas condenser 12, where the oil and water are condensed and collected. The non-condensable combustible gas is processed in the purification tank 15 to remove impurities, chlorine and solid silicon and then collected by the storage equipment 16; the carbon slag falls into the cold spiral slag discharger and is continuously cooled during the transportation process until it is collected by the receiving silo 20 and finally falls into the ton bag 21 for transportation.

[0049] Adaptive changes made according to actual needs are all within the protection scope of the present invention.

[0050] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any reference numerals in the claims should not be regarded as limiting the claims involved.

[0051] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A continuous mixed type harmless pyrolysis treatment system for waste plastics, characterized in that: It comprises a pyrolysis reactor, wherein a screw pusher for conveying plastic is arranged in the pyrolysis chamber of the pyrolysis reactor, and the pyrolysis chamber of the pyrolysis reactor is divided into a plurality of heating sections along the pushing direction of the screw pusher, and the heating temperatures of different heating sections correspond to the pyrolysis temperatures required for pyrolyzing plastics of different materials to produce oil and gas, and along the pushing direction of the screw pusher, the temperatures of the plurality of heating sections are successively increased, and waste plastics of different materials are pyrolyzed in different heating sections respectively, and the pyrolysis of the waste plastics is completed in different heating sections, and the pyrolysis reactor comprises the screw pusher, a heat transfer inner cylinder with heat transfer characteristics, and a heat insulation outer cylinder for heat preservation, which are sequentially sleeved from the inside to the outside, and the inner cavity of the heat transfer inner cylinder is the pyrolysis chamber, and a heating coil installation cavity is formed between the heat insulation outer cylinder and the heat transfer inner cylinder, and the heating coil installation cavity comprises a plurality of heating sections arranged corresponding to the heating sections, and the plurality of heating sections are all provided with electric heating coils, and the electric heating coils in adjacent heating sections are arranged at intervals; It also includes a feeding unit, which includes a feeder, a screw feeder and a conveying mechanism for conveying plastic to the feeder, the discharge port of the feeder is connected to the feed port of the screw feeder, the discharge port of the screw feeder is connected to the pyrolysis chamber of the pyrolysis reactor, and the screw feeder is provided with a heating module for heating the plastic to a molten state; The conveying mechanism includes a first conveyor, a briquetting machine for pressing plastic into blocks, and a second conveyor, wherein one end of the first conveyor is located above the feed port of the briquetting machine, and the other end is arranged on the ground, and one end of the second conveyor is located below the discharge port of the briquetting machine, and the other end is located above the feed port of the dropper; The continuous mixed waste plastic harmless pyrolysis disposal system also includes a solid product processing unit, which includes a plurality of water-cooled spiral slag dischargers and a receiving silo connected in sequence, and the feed port of the first water-cooled spiral slag discharger is connected to the discharge port of the pyrolysis chamber; the plurality of water-cooled spiral slag dischargers are arranged obliquely, and the discharge ports of the water-cooled spiral slag dischargers are higher than the feed ports, and the feed port of the rear water-cooled spiral slag discharger is located below the discharge port of the front water-cooled spiral slag discharger, and the first water-cooled spiral slag discharger is provided with a cooling water inlet, and the cooling water inlet is located at the feed port of the first water-cooled spiral slag discharger.

2. The continuous mixed waste plastic harmless pyrolysis treatment system according to claim 1 is characterized in that: The continuous mixed waste plastic harmless pyrolysis disposal system also includes a gas product processing unit, which includes a catalytic tower for removing impurity components, a plurality of oil and gas condensers for separating oil and gas, and a non-condensable combustible gas collection system for collecting non-condensable combustible gas, which are connected in sequence. The air inlet of the catalytic tower is connected to the outlet of the heat transfer inner cylinder.

3. The continuous mixed waste plastic harmless pyrolysis treatment system according to claim 2 is characterized in that: The non-condensable combustible gas collection system includes a plurality of purification tanks for storing water or reactants and storage equipment for storing non-condensable combustible gas. The plurality of purification tanks are connected in sequence, and the end of the purification tank is connected to the storage equipment. The purification tank is provided with an air inlet pipe and an air outlet pipe connected to the air outlet of the oil-gas condenser. One end of the air inlet pipe away from the oil-gas condenser extends into the cavity of the purification tank and is submerged in water or reactants. The air outlet pipe is arranged on the top of the purification tank.

4. The continuous mixed waste plastic harmless pyrolysis treatment system according to claim 1 is characterized in that: A buffer is provided at the outlet of the heat transfer inner cylinder, and the bottom of the buffer is connected to the water-cooled spiral slag discharger through a valve.

5. A method for harmless pyrolysis treatment of continuous mixed waste plastics using a harmless pyrolysis treatment system according to claim 3, characterized in that: The following steps are involved: S1: The mixed waste plastics are transported to the briquetting machine by the first conveyor for compaction, and the air contained therein is discharged, and then transported to the blanking device by the second conveyor for unloading; S2: Blocky mixed waste plastics enter the screw feeder and are transported to the heat transfer inner cylinder. During the transportation process, they are heated to a molten state and some moisture is removed. S3: The molten mixed waste plastics move in the heat transfer inner cylinder and pass through the heating areas formed by several heating sections in the heat transfer inner cylinder in sequence. Plastics of different materials are pyrolyzed in different heating areas to generate oil, gas and carbon slag. S4: After the oil and gas pass through the catalytic tower to remove impurities, they enter the oil and gas condenser, where the oil and water are condensed and collected, and the non-condensable combustible gas is processed in the purification tank and then collected by the storage equipment; The carbon slag falls into the water-cooled spiral slag discharger and is continuously cooled during the transportation process until it is collected by the receiving silo.

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