Cracking device for waste plastics

Abstract

The invention discloses a cracking device for waste plastics, and relates to the technical field of cracking of waste plastics, the cracking device comprises a reaction tube, a back pressure container is arranged above the reaction tube, the top end of the back pressure container is connected with a pressure pump through a first gas delivery pipe, and a discharge pipe extending into the reaction tube is fixed at the bottom end of the back pressure container; high-pressure airflow is injected into the backpressure container through the pressure pump, so that waste plastic particles can be instantaneously brought into the discharge pipe by the high-pressure airflow, second-level feeding of gram-level plastic is realized, the plastic can quickly perform heat transfer with a high-temperature heat carrier in a thermal cracking section in the reaction pipe, the heat transfer rate is increased, coke is reduced, and the energy consumption is reduced. The defect that more coke is generated due to the fact that plastic is slowly heated and cracked from the room temperature is overcome, pyrolysis product distribution can be effectively improved, the subsequent catalytic modification reaction is facilitated, meanwhile, reaction products obtained after thermal cracking can rapidly enter the catalytic modification section to be subjected to the catalytic modification reaction, coupling of thermal cracking and catalytic modification is achieved, and the service life of the catalytic modification section is prolonged. And the conversion efficiency of the waste plastics to high-added-value products is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of waste plastic pyrolysis technology, and more particularly to a waste plastic pyrolysis device. Background Technology

[0002] Plastics are polymers made from monomers through addition or condensation polymerization. Plastic products refer to various items made primarily from plastics, which are widely used in daily life, industrial production, medical care, construction, and many other fields. With social development and technological progress, various plastic products have entered all aspects of social life and played a huge role. However, this has also led to an increasing amount of plastic waste that is not easily degraded, causing white pollution. Therefore, it is necessary to recycle waste plastics.

[0003] Currently, the main method for chemical recycling of waste plastics is pyrolysis, which has a pyrolysis mechanism similar to thermal pyrolysis and catalytic pyrolysis in petrochemicals. These methods decompose large molecules into smaller molecules either under the action of heat or a catalyst. The methods employed include thermal pyrolysis, catalytic pyrolysis, or a combination of both. However, research on the catalytic pyrolysis of waste plastics is still immature, especially the development of catalysts, which is still in the laboratory-scale research stage. Slowly heating and pyrolyzing plastics at room temperature produces a large amount of coke, which is detrimental to subsequent catalytic reforming reactions and results in a poor overall product distribution. Furthermore, existing thermal pyrolysis devices are complex in structure, difficult to operate, and cannot effectively improve the conversion efficiency of waste plastics into high-value-added products. Therefore, this invention proposes a pyrolysis device for waste plastics to solve the problems existing in the prior art. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a pyrolysis device for waste plastics, which solves the problems of existing waste plastic pyrolysis technologies producing a large amount of coke, which is not conducive to subsequent catalytic reforming reactions, resulting in poor overall product distribution, as well as the problems of existing pyrolysis devices having complex structures, being difficult to operate, and having low catalyst evaluation efficiency.

[0005] To achieve the objectives of this invention, the following technical solution is provided: a pyrolysis device for waste plastics, comprising a reaction tube, a back pressure container above the reaction tube, a pressure pump connected to the top of the back pressure container via a first gas supply pipe, a discharge pipe extending into the reaction tube fixed at the bottom of the back pressure container, an inert gas storage tank connected to the side wall of the discharge pipe via a second gas supply pipe, a condensing sleeve fitted outside the discharge pipe, the condensing sleeve being sealed to the reaction tube via a sealing flange, a metal mesh embedded and inserted inside the reaction tube and divided into a thermal pyrolysis section and a catalytic reforming section distributed vertically by the metal mesh, the catalytic reforming section being filled with a catalyst, a first tubular open furnace and a second tubular open furnace distributed vertically and corresponding to the thermal pyrolysis section and the catalytic reforming section being fitted outside the reaction tube, a cold trap below the reaction tube, an exhaust pipe fixed at the bottom of the reaction tube, a serpentine condensing tube fixed at the bottom of the exhaust pipe and located within the cold trap, and a drainage and gas collection assembly connected to the end of the serpentine condensing tube away from the exhaust pipe via an outlet pipe.

[0006] A further improvement is that the drainage and gas collection assembly includes a gas collection container connected to the gas outlet pipe and a drain pipe fixed to the lower part of the side wall of the gas collection container. A water collection container is provided above the gas collection container, and the end of the drain pipe away from the gas collection container extends into the interior of the water collection container.

[0007] Further improvements include: a base plate at the bottom of the cold trap and gas collection container, a vertical plate fixed to the rear side of the top of the base plate, a first support plate symmetrically fixed to the front of the vertical plate below the second tubular open furnace, a second support plate fixed to the front of the vertical plate below the pressure pump, a support frame fixed to the front of the vertical plate at the bottom of the inert gas storage tank, a third support plate fixed to the front of the vertical plate below the water collection container, a weighing scale placed on the top of the third support plate, and the water collection container placed on the weighing scale.

[0008] A further improvement is that electronic control valves are installed on both the first and second gas supply pipes, and the outlet of the inert gas storage tank is connected to the second gas supply pipe via a mass flow meter. The inert gas stored in the inert gas storage tank is selected from either argon or nitrogen.

[0009] A further improvement is that the condensing medium inside the condensing sleeve is tap water, an inlet pipe is fixed to the upper part of the side wall of the condensing sleeve near the inert gas storage tank, one end of the inlet pipe extends to the lower part of the interior of the condensing sleeve, and an outlet pipe is fixed to the upper part of the side wall of the condensing sleeve away from the inlet pipe.

[0010] A further improvement is that: an upper connecting flange is fixedly sleeved on the outer wall of the condenser sleeve, a lower connecting flange adapted to the upper connecting flange is fixed at the top of the reaction tube, a graphite gasket is fixed at the bottom of the upper connecting flange, an annular groove adapted to the graphite gasket is opened at the top of the lower connecting flange, and the upper connecting flange and the lower connecting flange are fixedly connected by bolts.

[0011] A further improvement is made in that: a first thermocouple measuring instrument is fixed at the bottom of the reaction tube, the detection end of the first thermocouple measuring instrument penetrates through the bottom of the reaction tube and extends into the interior of the catalytic reforming section, a first thermocouple sleeve is fitted around the first thermocouple measuring instrument, a second thermocouple measuring instrument is fixed at the upper part of the side wall of the reaction tube, the detection end of the second thermocouple measuring instrument penetrates through the side wall of the reaction tube and extends into the interior of the thermal decomposition section, and a second thermocouple sleeve is fitted around the second thermocouple measuring instrument.

[0012] A further improvement is that the bottom of the back pressure container is tapered, the filling pressure inside the back pressure container is 0.2 to 0.5 MPa, the material of the reaction tube is selected from one of 310s stainless steel, 316L stainless steel or 304 stainless steel, and the material of the metal mesh is selected from one of 310s stainless steel, 316L stainless steel or 304 stainless steel.

[0013] A further improvement is that the condensing medium in the cold trap is a mixture of water and ethylene glycol in a mass ratio of 1:1, and the temperature of the condensing medium in the cold trap is -18 to -10°C.

[0014] The beneficial effects of this invention are as follows: This invention fills a back-pressure container with waste plastic particles and injects a high-pressure airflow into the back-pressure container through a pressure pump, so that the waste plastic particles can be instantly carried into the discharge pipe by the high-pressure airflow, thereby achieving gram-level plastic feeding in seconds. The plastic can quickly transfer heat with the high-temperature heat carrier in the pyrolysis section of the reaction tube, enhancing the heat transfer rate, reducing the generation of coke, and avoiding the disadvantage of the plastic slowly being heated and decomposed from room temperature, which produces a lot of coke. It can effectively improve the distribution of pyrolysis products, which is beneficial to the subsequent catalytic reforming reaction. At the same time, the reaction products after pyrolysis can quickly enter the catalytic reforming section for catalytic reforming reaction, realizing the coupling of pyrolysis and catalytic reforming. In addition, the entire pyrolysis device has a simple structure, is easy to operate, improves product distribution, and improves catalyst evaluation efficiency. Attached Figure Description

[0015] Figure 1 This is a front view of the present invention;

[0016] Figure 2 This is a front sectional view of the present invention;

[0017] Figure 3 This is a cross-sectional view of the back pressure container of the present invention;

[0018] Figure 4 This is a cross-sectional view of the reaction tube of the present invention.

[0019] The components include: 1. Reaction tube; 2. Back pressure vessel; 3. First gas delivery pipe; 4. Pressure pump; 5. Discharge pipe; 6. Second gas delivery pipe; 7. Inert gas storage tank; 8. Condensation sleeve; 9. Metal mesh; 10. First tubular open furnace; 11. Second tubular open furnace; 12. Cold trap; 13. Exhaust pipe; 14. Serpentine condenser; 15. Gas outlet pipe; 16. Gas collection container; 17. Drain pipe; 18. Water collection container; 19. Vertical plate; 20. First support. 21. Second support plate; 22. Support frame; 23. Third support plate; 24. Measuring scale; 25. Mass flow meter; 26. Inlet pipe; 27. Outlet pipe; 28. Upper connecting flange; 29. ​​Lower connecting flange; 30. Graphite gasket; 31. First thermocouple measuring instrument; 32. First thermocouple sheath; 33. Base plate; 34. Second thermocouple measuring instrument; 35. Second thermocouple sheath; 101. Thermal decomposition section; 102. Catalytic reforming section. Detailed Implementation

[0020] 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.

[0021] Example 1

[0022] See Figure 1 , Figure 2 , Figure 3 , Figure 4This embodiment provides a waste plastic pyrolysis device, including a reaction tube 1 made of 310s stainless steel and a back pressure container 2 located above the reaction tube 1 for filling with waste plastic fragments to be pyrolyzed. A first gas supply pipe 3 is fixed to the top of the back pressure container 2, and an electronic control valve is installed on the first gas supply pipe 3. The end of the first gas supply pipe 3 away from the back pressure container 2 is the gas inlet end and is connected to a pressure pump 4. The pressure pump 4 provides high-pressure gas flow to the back pressure container 2 through the first gas supply pipe 3. A discharge pipe 5 is fixed to the bottom of the back pressure container 2, and the lower part of the discharge pipe 5 extends into the interior of the reaction tube 1. A valve is also installed on the discharge pipe 5 to facilitate control of the discharge. The upper part of the right side wall of the discharge pipe 5 is fixed with a second gas supply pipe 6 and an electronic control valve is installed on the second gas supply pipe 6. The end of the second gas supply pipe 6 away from the discharge pipe 5 is the gas inlet and is connected to an inert gas storage tank 7 for storing inert gas. The inert gas storage tank 7 provides inert gas to the reaction pipe 1 through the second gas supply pipe 6 as a heat carrier. The discharge pipe 5 is fitted with a condensing sleeve 8 for cooling the discharge pipe 5. The condensing sleeve 8 is sealed to the reaction pipe 1 through a sealing flange, so that the reaction pipe 1 and the discharge pipe 5 are connected, so that the waste plastic fragments in the discharge pipe 5 can flow into the reaction pipe 1.

[0023] A metal mesh 9 made of 310s stainless steel is embedded and inserted inside the reaction tube 1, dividing the internal space of the reaction tube 1 into upper and lower parts. The upper part is a pyrolysis section 101, used for the pyrolysis reaction of waste plastic fragments, and the lower part is a catalytic modification section 102. The catalytic modification section 102 is filled with a catalyst and used for the catalytic reaction of the pyrolysis products. The catalyst used in this embodiment is a microsphere catalyst with ZSM-5, Y-type or β molecular sieve as the active component. The upper part of the outer wall of the reaction tube 1 is fitted with a metal mesh 9 made of 310s stainless steel. A first tubular open furnace 10 is provided at the position of the pyrolysis section 101. A second tubular open furnace 11 is provided at the lower part of the outer wall of the reaction tube 1, corresponding to the position of the catalytic reforming section 102. The pyrolysis section 101 is heated by the first tubular open furnace 10, and the catalytic reforming section 102 is heated by the second tubular open furnace 11. The two-stage heating achieves segmented temperature control. A cold trap 12 is provided below the reaction tube 1 for cooling the catalytic reforming reaction products. An exhaust pipe 13 connected to the catalytic reforming section 102 is fixed at the bottom of the reaction tube 1.

[0024] A serpentine condenser 14 is fixed to the bottom of the exhaust pipe 13 and is used to collect the condensate of the catalytic reforming reaction products. The serpentine condenser 14 is located inside the cold trap 12. The end of the serpentine condenser 14 away from the exhaust pipe 13 is fixed to an outlet pipe 15 and is connected to it. The other end of the outlet pipe 15 extends to the outside of the cold trap 12 and is connected to a drainage and gas collection assembly. The gas products in the serpentine condenser 14 are collected by the drainage and gas collection assembly. Waste plastic particles are filled into the back pressure container 2 and high-pressure gas flow is injected into the back pressure container 2 by the pressure pump 4. The waste plastic particles can be instantly carried into the discharge pipe 5 by the high-pressure gas flow, thereby achieving gram-level plastic feeding in seconds. The plastic can quickly transfer heat with the high-temperature heat carrier of the pyrolysis section 101 in the reaction tube 1, enhance the heat transfer rate, reduce the generation of coke, and avoid the disadvantage of the plastic slowly being heated and decomposed from room temperature to produce more coke. It can effectively improve the distribution of pyrolysis products and is beneficial to the subsequent catalytic reforming reaction.

[0025] The drainage and gas collection assembly includes a gas collection container 16 and a drain pipe 17. The gas collection container 16 stores water and is connected to the gas outlet pipe 15. The drain pipe 17 is fixed to the lower part of the right side wall of the gas collection container 16. A water collection container 18 is provided above the gas collection container 16 for collecting the drainage in the gas collection container 16. The end of the drain pipe 17 away from the gas collection container 16 extends into the water collection container 18. The catalytic reaction products are carried out of the reaction tube 1 by the gas flow and injected into the serpentine condenser tube 14 through the exhaust pipe 13. At this time, under the cooling effect of the cold trap 12, a portion of the products in the serpentine condenser tube 14 condenses. The gas that cannot be condensed is injected into the gas collection container 16 through the gas outlet pipe 15. As the gas increases, the water in the gas collection container 16 is pressurized and injected into the water collection container 18 through the water outlet pipe 27.

[0026] The cold trap 12 and the gas collection container 16 are both provided with a base plate 33 at their bottom ends, which provides support for the cold trap 12 and the gas collection container 16. A vertical plate 19 is welded and fixed to the rear side of the top of the base plate 33. A first support plate 20 is symmetrically provided below the second tubular open furnace 11, and the first support plate 20 is welded and fixed to the front of the vertical plate 19 to provide support for the second tubular open furnace 11. A second support plate 21 is provided below the pressure pump 4, and the second support plate 21 is welded and fixed to the front of the vertical plate 19 to provide support for the pressure pump 4. Inert gas A support frame 22 is fitted at the bottom of the gas storage tank 7, and the support frame 22 is welded and fixed to the front of the upright plate 19 to provide support for the inert gas storage tank 7. A third support plate 23 is provided below the water collection container 18, and the third support plate 23 is welded and fixed to the front of the upright plate 19. A weighing scale 24 is placed at the top of the third support plate 23, and the water collection container 18 is placed on the weighing scale 24. The mass change of water in the water collection container 18 is recorded by the weighing scale 24, so as to calculate the mass of gas received in the gas collection container 16 by means of the gas state equation.

[0027] The outlet of the inert gas storage tank 7 is connected to the second gas supply pipe 6 via a mass flow meter 25. The inert gas in the inert gas storage tank 7, after the flow rate is controlled by the mass flow meter 25, enters the reaction pipe 1 through the second gas supply pipe 6. The inert gas stored in the inert gas storage tank 7 is nitrogen.

[0028] The condensing medium inside the condenser sleeve 8 is tap water at 20°C. An inlet pipe 26 for connecting to external tap water is fixed on the upper part of the left side wall of the condenser sleeve 8. One end of the inlet pipe 26 extends into the lower part of the condenser sleeve 8 to facilitate the injection of tap water into the condenser sleeve 8. An outlet pipe 27 is fixed on the upper part of the right side wall of the condenser sleeve 8 to facilitate the discharge of tap water from the condenser sleeve 8 to the external tap water recycling equipment.

[0029] The outer wall of the condenser sleeve 8 is fixedly fitted with an upper connecting flange 28, and the top of the reaction tube 1 is fixed with a lower connecting flange 29. The lower connecting flange 29 is compatible with the upper connecting flange 28 and the two are fixed together by bolts. A graphite gasket 30 is fixed at the bottom of the upper connecting flange 28, and an annular groove that is compatible with the graphite gasket 30 is opened at the top of the lower connecting flange 29 to improve the sealing between the lower connecting flange 29 and the upper connecting flange 28.

[0030] A first thermocouple measuring instrument 31 for temperature measurement is fixed at the bottom of the reaction tube 1. The detection end of the first thermocouple measuring instrument 31 passes through the bottom of the reaction tube 1 and extends into the catalytic reforming section 102. A first thermocouple sheath 32 is sleeved on the outside of the first thermocouple measuring instrument 31. The actual temperature inside the catalytic reforming section 102 is measured by the first thermocouple measuring instrument 31, while the first thermocouple sheath 32 plays a protective role.

[0031] A second thermocouple measuring instrument 34 for temperature measurement is fixed on the upper part of the side wall of the reaction tube 1. The detection end of the second thermocouple measuring instrument 34 penetrates through the side wall of the reaction tube 1 and extends into the interior of the pyrolysis section 101. It is positioned on the left to avoid affecting the feed. A second thermocouple sheath 35 is sleeved on the outside of the second thermocouple measuring instrument 34. The actual temperature inside the pyrolysis section 101 is measured by the second thermocouple measuring instrument 34, while the second thermocouple sheath 35 serves a protective function.

[0032] The bottom of the back pressure container 2 is tapered, and the angle between the tapered part and the horizontal line is 50°. The filling pressure inside the back pressure container 2 is 0.2MPa.

[0033] The condensing medium inside the cold trap 12 is a mixture of water and ethylene glycol in a mass ratio of 1:1, and the temperature of the condensing medium inside the cold trap 12 is -13℃.

[0034] Example 2

[0035] See Figure 1 , Figure 2, Figure 3 , Figure 4 This embodiment provides a waste plastic pyrolysis device. The difference from Embodiment 1 is that the reaction tube 1 is made of 316L stainless steel, the metal mesh 9 is made of 316L stainless steel, the filling pressure in the back pressure container 2 is 0.35MPa, the temperature of the condensing medium in the cold trap 12 is -18℃, and the angle between the bottom conical part of the back pressure container 2 and the horizontal line is 55°.

[0036] Example 3

[0037] See Figure 1 , Figure 2 , Figure 3 , Figure 4 This embodiment provides a pyrolysis device for waste plastics. The difference from Embodiment 1 is that the reaction tube 1 is made of 304 stainless steel, the metal mesh 9 is made of 304 stainless steel, the filling pressure in the back pressure container 2 is 0.5 MPa, and the temperature of the condensing medium in the cold trap 12 is -10°C.

[0038] When pyrolysis of waste plastics is required, the waste plastic fragments to be pyrolyzed are pre-filled into the back pressure container 2. The first tubular open furnace 10 and the second tubular open furnace 11 are turned on to heat the reaction tube 1 to a preset temperature. After the temperature stabilizes, the pressure pump 4 is started to fill the back pressure container with a high-pressure gas flow of 0.5 MPa, and the valve of the discharge pipe 5 at the bottom of the back pressure container 2 is opened, so that the waste plastic fragments in the back pressure container 2 are instantly carried into the discharge pipe 5 by the high-pressure gas flow. At the same time, the inert gas storage tank 7 is turned on to inject inert gas into the discharge pipe 5 (the gas flow rate is controlled by the mass flow meter 25). Then, the waste plastic fragments are injected from the discharge pipe 5 into the pyrolysis section 101 in the reaction tube 1. At this time, the inert gas is used as a heat carrier to cause the waste plastic fragments to undergo a pyrolysis reaction (the heating temperature of the pyrolysis section 101 is controlled at 300-600℃). During the pyrolysis, the inert gas is used to generate heat. The condensing medium in the condensing sleeve 8 cools the discharge pipe 5 to prevent the temperature in the reaction tube 1 from radiating upwards. The intermediate products of the thermal cracking reaction continue to flow downwards through the metal mesh 9 into the catalytic reforming section 102, where they come into contact with the catalyst and undergo a catalytic reforming reaction (the heating temperature of the catalytic reforming section 102 is controlled at 400-800℃). The catalytic reaction products are carried out of the reaction tube 1 by the gas flow and injected into the serpentine condenser 14 through the exhaust pipe 13. At this time, under the cooling effect of the cold trap 12, a portion of the products in the serpentine condenser 14 condenses. The gas that cannot be condensed is injected into the gas collection container 16 through the gas outlet pipe 15. As the gas increases, the water in the gas collection container 16 is pressurized and injected into the water collection container 18 through the water outlet pipe 27. Finally, the mass change of the water in the water collection container 18 is recorded by the metering scale 24 to calculate the mass of the gas collected in the gas collection container 16.

[0039] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pyrolysis device for waste plastics, comprising a reaction tube (1), characterized in that: A back pressure container (2) is provided above the reaction tube (1). A pressure pump (4) is connected to the top of the back pressure container (2) through a first gas supply pipe (3). A discharge pipe (5) extending into the reaction tube (1) is fixed at the bottom of the back pressure container (2). An inert gas storage tank (7) is connected to the side wall of the discharge pipe (5) through a second gas supply pipe (6). A condensing sleeve (8) is fitted outside the discharge pipe (5). The condensing sleeve (8) is sealed to the reaction tube (1) through a sealing flange. A metal mesh (9) is embedded inside the reaction tube (1) and is divided into a vertically distributed pyrolysis section (101) and a horizontally distributed pyrolysis section (101). The catalytic reforming section (102) is filled with a catalyst. The reaction tube (1) is fitted with a first tubular open furnace (10) and a second tubular open furnace (11) that are distributed vertically and correspond to the thermal cracking section (101) and the catalytic reforming section (102). A cold trap (12) is provided below the reaction tube (1). An exhaust pipe (13) is fixed at the bottom of the reaction tube (1). A serpentine condenser (14) located in the cold trap (12) is fixed at the bottom of the exhaust pipe (13). The end of the serpentine condenser (14) away from the exhaust pipe (13) is connected to a drainage and gas collection assembly through an outlet pipe (15).

2. The pyrolysis device for waste plastics according to claim 1, characterized in that: The drainage and gas collection assembly includes a gas collection container (16) connected to the gas outlet pipe (15) and a drain pipe (17) fixed to the lower part of the side wall of the gas collection container (16). A water collection container (18) is provided above the gas collection container (16), and one end of the drain pipe (17) away from the gas collection container (16) extends into the interior of the water collection container (18).

3. The pyrolysis device for waste plastics according to claim 2, characterized in that: The cold trap (12) and the gas collection container (16) are provided with a base plate (33) at the bottom end. A vertical plate (19) is fixed to the rear side of the top of the base plate (33). A first support plate (20) is symmetrically provided below the second tubular open furnace (11) and fixed to the front of the vertical plate (19). A second support plate (21) is provided below the pressure pump (4) and fixed to the front of the vertical plate (19). A support frame (22) is fitted at the bottom of the inert gas storage tank (7) and fixed to the front of the vertical plate (19). A third support plate (23) is provided below the water collection container (18) and fixed to the front of the vertical plate (19). A weighing scale (24) is placed on the top of the third support plate (23) and the water collection container (18) is placed on the weighing scale (24).

4. The pyrolysis device for waste plastics according to claim 1, characterized in that: Electronic control valves are installed on both the first gas supply pipe (3) and the second gas supply pipe (6). The outlet of the inert gas storage tank (7) is connected to the second gas supply pipe (6) through a mass flow meter (25). The inert gas stored in the inert gas storage tank (7) is selected from either argon or nitrogen.

5. The pyrolysis device for waste plastics according to claim 1, characterized in that: The condensing medium inside the condensing sleeve (8) is tap water. A water inlet pipe (26) is fixed on the upper part of the side wall of the condensing sleeve (8) near the inert gas storage tank (7). One end of the water inlet pipe (26) inside the condensing sleeve (8) extends to the lower part of the interior of the condensing sleeve (8). A water outlet pipe (27) is fixed on the upper part of the side wall of the condensing sleeve (8) away from the water inlet pipe (26).

6. The pyrolysis device for waste plastics according to claim 1, characterized in that: The outer wall of the condenser sleeve (8) is fixedly fitted with an upper connecting flange (28), the top of the reaction tube (1) is fixed with a lower connecting flange (29) that is compatible with the upper connecting flange (28), the bottom of the upper connecting flange (28) is fixed with a graphite gasket (30), the top of the lower connecting flange (29) is provided with an annular groove that is compatible with the graphite gasket (30), and the upper connecting flange (28) and the lower connecting flange (29) are fixedly connected by bolts.

7. The pyrolysis device for waste plastics according to claim 1, characterized in that: A first thermocouple measuring instrument (31) is fixed at the bottom of the reaction tube (1). The detection end of the first thermocouple measuring instrument (31) penetrates the bottom of the reaction tube (1) and extends into the catalytic reforming section (102). A first thermocouple sleeve (32) is fitted outside the first thermocouple measuring instrument (31). A second thermocouple measuring instrument (34) is fixed at the upper part of the side wall of the reaction tube (1). The detection end of the second thermocouple measuring instrument (34) penetrates the side wall of the reaction tube (1) and extends into the thermal decomposition section (101). A second thermocouple sleeve (35) is fitted outside the second thermocouple measuring instrument (34).

8. The pyrolysis device for waste plastics according to claim 1, characterized in that: The bottom of the back pressure container (2) is conical. The filling pressure inside the back pressure container (2) is 0.2 to 0.5 MPa. The material of the reaction tube (1) is selected from 310s stainless steel, 316L stainless steel or 304 stainless steel. The material of the metal mesh (9) is selected from 310s stainless steel, 316L stainless steel or 304 stainless steel.

9. The pyrolysis device for waste plastics according to claim 1, characterized in that: The condensing medium in the cold trap (12) is a mixture of water and ethylene glycol in a mass ratio of 1:1, and the temperature of the condensing medium in the cold trap (12) is -18 to -10°C.

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