Pyrolysis method of waste polymer materials

Abstract

The application belongs to the technical field of solid waste treatment, and relates to a pyrolysis method of waste and old high polymer materials. The pyrolysis method is to make the waste and old high polymer materials pyrolyze in a pyrolysis reactor, and the pyrolysis reactor comprises a stirring handle, the handle comprises a scraper and an elastic member; the elastic member is arranged to be capable of adjusting the inclination angle of the scraper, so that the scraper can continuously contact the inner wall of the pyrolysis reactor and play a scraping role. By using the pyrolysis method of waste and old high polymer materials, the coking produced by pyrolysis on the reactor wall surface can be better removed when the waste and old high polymer materials are pyrolyzed, so that the pyrolysis oil yield and quality of the waste and old high polymer materials pyrolysis are improved on the basis of improving the heat transfer efficiency of the reactor.

Description

A pyrolysis method for waste polymer materials Technical Field

[0001] This application belongs to the field of solid waste treatment technology and relates to a pyrolysis method for waste polymer materials. Background Technology

[0002] Improper disposal of waste polymer materials, such as waste tires, waste rubber, and synthetic fiber clothing waste, can cause environmental pollution and waste usable resources. Furthermore, with the rapid development of my country's textile and synthetic rubber industries, the amount of waste polymer materials generated will continue to increase, leading to secondary pollution if not properly treated. Therefore, the reduction, harmless treatment, and resource recovery of waste polymer materials are urgently needed.

[0003] Through the design, manufacturing, and control of process conditions, countries around the world have developed spiral reactors, fluidized bed reactors, and rotary kiln reactors. However, many problems still exist in the pyrolysis process, such as the easy agglomeration and undercooking of materials, resulting in incomplete pyrolysis; coking on the inner wall causing thermal stagnation and reduced heat exchange efficiency; unsatisfactory pyrolysis oil yield and low pyrolysis oil quality; short operating cycle of pyrolysis methods, and high shutdown and maintenance costs.

[0004] In order to fully pyrolyze waste polymer materials and obtain higher quality pyrolysis oil, new research is needed on pyrolysis methods. Summary of the Invention

[0005] The purpose of this application is to provide a pyrolysis method for waste polymer materials, which can better remove the coking products generated during pyrolysis on the reactor wall, thereby improving the yield and quality of pyrolysis oil from the waste polymer materials based on improving the heat transfer efficiency of the reactor.

[0006] To achieve this objective, in a basic implementation scheme, this application provides a method for pyrolyzing waste polymer materials. The pyrolysis method includes: pyrolyzing the waste polymer materials in a pyrolysis reactor, the pyrolysis reactor including a stirring handle, the stirring handle including a scraper and an elastic element; the elastic element is configured to adjust the tilt angle of the scraper so that the scraper can continuously contact the inner wall of the pyrolysis reactor and perform a scraping action.

[0007] In one embodiment, the elastic element is a tension spring and / or a compression spring.

[0008] In one embodiment, the tension spring has a wire diameter of 2-3 mm, a diameter of 20-35 mm, and an elastic deformation in the range of 15%-25%.

[0009] In one embodiment, the compression spring has a wire diameter of 2-3 mm, a diameter of 20-35 mm, and an elastic deformation in the range of 20-25%.

[0010] In one embodiment, the end of the scraper that contacts the inner wall of the pyrolysis reactor is fan-shaped, and the radius R of the fan-shaped area is 0.5-1 times the thickness of the scraper.

[0011] In this application, the waste polymer material is selected from one or more of waste tires, waste rubber, and synthetic fiber clothing waste.

[0012] In one implementation, the pyrolysis temperature is 400℃-500℃.

[0013] In one embodiment, the waste polymer material is further subjected to crushing and / or dehydration pretreatment before being fed into the pyrolysis reactor.

[0014] In one embodiment, the size of the crushed waste polymer material is no greater than 10 mm.

[0015] In one embodiment, the pyrolysis method includes multiple pyrolysis reactors connected in series and / or in parallel.

[0016] In general, the pyrolysis method of this application involves feeding waste polymer materials into a pyrolysis reactor for pyrolysis. The pyrolysis gas obtained from the pyrolysis is discharged from the outlet of the pyrolysis reactor and then condensed to obtain pyrolysis oil and pyrolysis fuel. The pyrolysis solid obtained from the pyrolysis is discharged from the outlet of the pyrolysis reactor and then cooled to obtain pyrolysis char.

[0017] In one embodiment, the pyrolysis reactor described in this application is indirectly heated by flue gas. Waste polymer materials undergo pyrolysis in an oxygen-free environment.

[0018] In a specific implementation scheme, the pyrolysis reactor of this application further includes a feed inlet, a discharge outlet, a pyrolysis gas outlet, a rotating shaft, a connecting rod, a scraper, a connecting sleeve, and tension springs and / or compression springs.

[0019] The rotating shaft is located at the center of the pyrolysis reactor, and one or more connecting rods are connected along the axial direction of the rotating shaft, with each connecting rod connected to a scraper.

[0020] Driven by the rotating shaft, the scraper rotates close to the inner wall of the pyrolysis reactor to scrape off the coking material that adheres to the inner wall due to pyrolysis.

[0021] The middle part of the scraper surface is connected to the connecting rod through the connecting sleeve, so that the scraper can rotate about the central axis of the connecting sleeve.

[0022] In one embodiment of the tension spring, the tension spring is disposed on the plate surface at one end of the scraper that is away from the inner wall of the pyrolysis reactor as the scraper rotates with the rotating shaft, and is connected to the connecting rod for applying tension to the scraper.

[0023] In one embodiment of the compression spring, the compression spring is disposed on the plate surface of one end of the scraper that is in contact with the inner wall of the pyrolysis reactor as the scraper rotates with the rotating shaft, and is connected to the connecting rod for applying pressure to the scraper to press against the inner wall of the pyrolysis reactor.

[0024] In one embodiment, the angle α between each of the connecting rods and the axis of rotation is independently 45-90°, preferably 75-85°.

[0025] Connect 2-2 connecting rods in different directions along a point on the axial direction of the rotation axis, such that the included angle between any two adjacent connecting rods formed therefrom is equal.

[0026] Preferably, the end of the scraper that contacts the inner wall of the pyrolysis reactor is fan-shaped.

[0027] In one embodiment, a spring outer sleeve is provided in addition to the tension spring and / or compression spring.

[0028] In one embodiment, the connecting rod and the compression spring are connected by a compression spring fixing rod.

[0029] In one embodiment, the pyrolysis method of this application includes multiple pyrolysis reactors connected in series and / or in parallel.

[0030] The beneficial effect of this application is that, by using the pyrolysis method of waste polymer materials of this application, it is possible to better remove the coking material generated by pyrolysis on the reactor wall surface when using it for pyrolysis of waste polymer materials, thereby improving the pyrolysis efficiency of waste polymer materials on the basis of improving the heat transfer efficiency of the reactor. Attached Figure Description

[0031] Figure 1 is a schematic cross-sectional view of the pyrolysis reactor in the pyrolysis method for waste polymer materials of this application, wherein the elastic element is a tension spring.

[0032] Figure 2 is a schematic cross-sectional view of the pyrolysis reactor in the pyrolysis method for waste polymer materials of this application, wherein the elastic element is a compression spring. Detailed Implementation

[0033] Waste polymer materials include waste tires, waste rubber, and synthetic fiber garment waste, etc. The pyrolysis of waste polymer materials in this application first involves pretreatment such as crushing and dehydration, and then the materials are fed into a pyrolysis reactor via a feeding device for pyrolysis at a temperature of 400℃-500℃. The high-temperature pyrolysis oil and gas produced by pyrolysis enters a condenser for separation, yielding pyrolysis oil and pyrolysis gas. The pyrolysis solids produced by pyrolysis are cooled and discharged, yielding pyrolysis char. The heat for the pyrolysis reactor can come from various heating methods, such as indirect heating using external flue gas, which is isolated from the waste polymer materials.

[0034] The pyrolysis of waste polymer materials generates a large amount of heat-labile oxygen-containing organic matter, which is prone to secondary decomposition and coking in the pyrolysis reactor. This coking adheres to the heated surfaces (i.e., the inner wall of the pyrolysis reactor), reducing the heat transfer efficiency and causing unstable pyrolysis temperatures, thus exacerbating secondary decomposition. Therefore, this application proposes a pyrolysis method for waste polymer materials, addressing the specific characteristics of waste polymer materials.

[0035] The pyrolysis method for waste polymer materials of this application may include one or more pyrolysis reactors. The pyrolysis reactor includes a feed inlet, a discharge outlet, a pyrolysis gas outlet, and a stirrer for agitating the material and scraping the inner wall of the reactor. In one specific embodiment, the pyrolysis reactor further includes a rotating shaft, a connecting rod, a scraper, a connecting sleeve, and an elastic element. The stirrer, consisting of the connecting rod, scraper, connecting sleeve, and elastic element, is fixedly connected to the rotating shaft via the connecting sleeve.

[0036] Waste polymer materials enter the pyrolysis reactor through the feed inlet for pyrolysis.

[0037] The pyrolysis solids produced after the pyrolysis of waste polymer materials are discharged from the pyrolysis reactor through the discharge port, and the pyrolysis oil and gas produced are discharged from the pyrolysis gas outlet of the pyrolysis reactor.

[0038] Figure 1 shows a schematic cross-sectional view of the pyrolysis reactor, in which the rotating shaft 2 is located at the center of the pyrolysis reactor, and one or more connecting rods 3 are connected along the axial direction of the rotating shaft 2, and each connecting rod 3 is connected to a scraper 4.

[0039] Driven by the rotating shaft 2, the scraper 4 can rotate closely inside the pyrolysis reactor and scrape off the coking material on the inner wall of the reactor.

[0040] The middle part of the scraper 4 is connected to the connecting rod 3 through the connecting sleeve 6, so that the scraper 4 can rotate about the central axis of the connecting sleeve 6.

[0041] In Figure 1, the elastic element is a tension spring. The tension spring 5 is a helical spring subjected to the axial tension of the rotating shaft 2. It is set on the plate surface of the scraper 4 at the end away from the inner wall 1 of the pyrolysis reactor as it rotates with the rotating shaft 2, and is connected to the connecting rod 3 to apply tension to the scraper 4, so that the scraper 4 is in closer contact with the inner wall 1 of the pyrolysis reactor.

[0042] In one implementation, the wire diameter of the tension spring is 2-3 mm, for example, 3 mm; the diameter is 20-35 mm, for example, 30 mm; the initial length is 110-130 mm, for example, 125 mm; and the maximum tensile length is 140-150 mm. The elastic deformation of the tension spring should not be too large, because if the deformation is too large, the spring may not be able to return to its original shape after the external force is removed. The elastic deformation of the tension spring should also not be too small, because if the deformation is too small, the tension will be too small, and insufficient scraping force will be generated. The preferred elastic deformation of the tension spring is in the range of 15%-25%.

[0043] In one embodiment, the angle α between each connecting rod and the axis of rotation is independently 45-90°, preferably 75-85°. Preferably, two-thirds of the connecting rods are inclined towards the discharge port and one-third are inclined towards the feed port, so that the material can be fully scooped up and mixed in the reactor and the residence time of the material in the reactor is extended.

[0044] In one implementation, multiple connecting rods are connected in different directions from a point along the axial direction of the rotation axis, and the included angle between any two adjacent connecting rods is equal.

[0045] Furthermore, the end of the scraper that contacts the inner wall of the pyrolysis reactor is fan-shaped, and the radius R of the fan-shaped area is 0.3-1 times the thickness of the scraper.

[0046] In one implementation, the length of the connecting rod is 0.5m to 0.8m.

[0047] In one implementation, the tension spring has a wire diameter of 3mm, a diameter of 30mm, an initial length of 125mm, and a maximum tensile length of 150mm.

[0048] In one embodiment, the scraper has a length of 10-20cm, for example 15cm; a thickness of 5-10mm, for example 8mm; and a width of 5-10cm, for example 8cm.

[0049] In one implementation, the rotational speed of the rotating shaft is 1-5 r / min.

[0050] In Figure 2, the elastic element is a compression spring. The compression spring 7 is a helical spring that bears axial pressure. It is located on the plate surface of one end of the scraper 4 that is in contact with the inner wall 1 of the pyrolysis reactor as it rotates with the rotating shaft 2. It is connected to the connecting rod 3 via the compression spring fixing rod 9 and is used to apply pressure to the scraper 4, causing the scraper 4 to generate a scraping force on the inner wall 1 of the pyrolysis reactor. A compression spring outer sleeve 8 is provided outside the compression spring 7. The compression spring outer sleeve 8 can maintain the axial deformation of the compression spring 7 and prevent bending deformation, thereby ensuring the axial compressive force of the compression spring 7. In one implementation, the spring has a wire diameter of 2-3 mm, e.g., 3 mm; a diameter of 20-35 mm, e.g., 30 mm; and an initial length of 110-140 mm, e.g., 130 mm. The elastic deformation of the spring should not be too large, as excessive deformation would prevent the scraper from generating sufficient resistance when in contact with the inner wall of the pyrolysis reactor, resulting in insufficient scraping force. Conversely, the elastic deformation should not be too small, as insufficient deformation would limit the rotation or tilting of the scraper, causing it to deform due to the reaction force of the inner wall, such as bending or breaking. An elastic deformation of 20-25% is suitable, allowing the scraper to generate appropriate resistance against the inner wall of the pyrolysis reactor, providing sufficient scraping force without deformation. The length of the spring under maximum compressive force can be 50-100 mm.

[0051] In this application, the scraper, constructed from elastic elements (tension and / or compression springs), scrapers, and connecting rods, possesses unique advantages. Under the tension and / or pressure of the elastic elements, the scraper can maintain close contact with the inner wall of the pyrolysis reactor, generating a suitable scraping force. This not only effectively removes coking deposits from the inner wall of the pyrolysis reactor but also prevents the scraper from deforming. Such a scraper is highly suitable for handling materials in a hot state. Furthermore, the scraper can tumble the scraped material for uniform heating and propel it towards the discharge port.

[0052] The waste polymer material pyrolysis method of this application may include multiple pyrolysis reactors, which are connected together in series and / or in parallel. The series and / or parallel connection is achieved by connecting the discharge port of the previous pyrolysis reactor with the inlet of the next pyrolysis reactor, preferably forming a 2-3 stage mixed pyrolysis reactor.

[0053] The following examples illustrate this application in detail.

[0054] In the following example, the waste polymer material is waste tires, and the size of the crushed material is ≤10mm.

[0055] Example 1:

[0056] In this embodiment, the pyrolysis reactor is shown in Figure 1, wherein: the length of the connecting rod 3 is 0.4m; the wire diameter of the tension spring 5 is 3mm, the diameter is 30mm, the original length is 125mm, and the maximum tensile length is 150mm; the scraper 4 is 15cm long, 8mm thick, and 8cm wide; the rotation speed of the rotating shaft 2 is 2r / min;

[0057] The shredded waste tires are fed into the pyrolysis reactor by a screw feeder. The pyrolysis reactor is a horizontal reactor with an inner diameter of 1.2m and a length of 8m, and its working efficiency is 2 tons / hour. The pyrolysis temperature is 500℃, and the residence time of the waste tires in the pyrolysis reactor is 30 minutes. The high-temperature pyrolysis oil and gas generated by pyrolysis are condensed in a condenser to obtain pyrolysis oil and pyrolysis gas, while the pyrolysis solids are discharged through the outlet. The pyrolysis method in this embodiment was continuously implemented for 60 days. The coking condition on the inner wall of the pyrolysis reactor was checked, and it was found that the average thickness of the coking material was 0.5mm, which was a thin black layer and was discharged from the outlet along with the pyrolysis solids. The handles and other components of the pyrolysis reactor showed no deformation. The analysis of the pyrolysis products is shown in Tables 1 and 2 below.

[0058] Table 1 Analysis of pyrolysis products:

[0059]

[0060] Table 2 shows the composition of the pyrolysis oil:

[0061]

[0062] Example 2:

[0063] This embodiment is the same as embodiment 1, except that the elastic element is a compression spring, as shown in Figure 2. The compression spring 7 has a wire diameter of 3mm, a diameter of 30mm, an original length of 130mm, and a compressed length of 100mm after use; the compression spring outer sleeve 8 has a length of 100mm and a diameter of 32mm; and the compression spring fixing rod 9 has a length of 120mm.

[0064] The pyrolysis method in this embodiment was continuously implemented for 60 days. The coking condition on the inner wall of the pyrolysis reactor was inspected. The average thickness of the coking material was found to be 0.7 mm, a thin, black layer, which was discharged from the outlet along with the pyrolysis solids. No deformation was observed in the handles and other components of the pyrolysis reactor. The analysis of the pyrolysis products is shown in Table 3-4 below.

[0065] Table 3 Analysis of pyrolysis products:

[0066]

[0067]

[0068] Table 4 shows the composition of the pyrolysis oil:

[0069]

[0070] Comparative Example 1:

[0071] This example is the same as Example 1, except that it lacks a tension spring.

[0072] The pyrolysis method was continuously implemented for 60 days. An inspection of the coking condition on the inner wall of the pyrolysis reactor revealed an average coking thickness of 5 mm, characterized by a hard, black substance, which was discharged from the outlet along with the pyrolysis solids. No deformation was observed in the scrapers and other components of the pyrolysis reactor.

[0073] The analysis of the pyrolysis products is shown in Table 5-6 below.

[0074] Table 5 Analysis of pyrolysis products:

[0075]

[0076] Table 6 shows the composition of the pyrolysis oil:

[0077]

[0078] Comparative Example 2:

[0079] This example is the same as Example 1, except that a spiral pyrolysis reactor is used for the pyrolysis reaction. The specifications of the spiral pyrolysis reactor are: inner diameter of 1.2m, length of 8m, and spiral pitch of 0.5m.

[0080] The pyrolysis method was continuously implemented for 60 days. The coking condition on the inner wall of the spiral pyrolysis reactor was checked. It was found that the average thickness of the coking material was 15 mm, and it was hard and black. It was discharged from the outlet along with the pyrolysis solids.

[0081] The analysis of the pyrolysis products is shown in Table 7-8 below.

[0082] Table 7 Analysis of pyrolysis products:

[0083]

[0084] Table 8 shows the composition of the pyrolysis oil:

[0085]

[0086] Overall, compared with rotary kiln pyrolysis reactors and spiral pyrolysis reactors, the advantages of the pyrolysis reactor of this application are as follows: because the scraper effectively removes the coking material inside the pyrolysis reactor, the heat exchange efficiency of the pyrolysis reactor of this application is higher as the pyrolysis reactor operates for a long time, which can ensure that the pyrolysis conditions remain stable for a long time, thus ensuring the quality of the pyrolysis products and improving the yield and quality of pyrolysis oil.

[0087] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations. The above embodiments or implementations are merely illustrative examples of this application, and this application can also be implemented in other specific ways or forms without departing from the gist or essential characteristics of this application. Therefore, the described implementations should be considered illustrative rather than limiting in any respect. The scope of this application should be defined by the appended claims, and any changes equivalent to the intent and scope of the claims should also be included within the scope of this application.

Claims

1. A method for pyrolyzing waste polymer materials, characterized in that: The pyrolysis method includes: pyrolyzing waste polymer materials in a pyrolysis reactor, the pyrolysis reactor including a stirring handle, the stirring handle including a scraper and an elastic element; the elastic element is configured to adjust the tilt angle of the scraper so that the scraper can continuously contact the inner wall of the pyrolysis reactor and perform a scraping action; the pyrolysis reactor also includes a rotating shaft, connecting rods and connecting sleeves, the rotating shaft being located at the center of the pyrolysis reactor, one or more connecting rods being connected along the axial direction of the rotating shaft, each connecting rod being connected to a scraper; the middle part of the scraper surface is connected to the connecting rod through the connecting sleeve; the elastic element is disposed on the plate surface of one end of the scraper that is in contact with the inner wall of the pyrolysis reactor during rotation with the rotating shaft, and is connected to the connecting rod through a compression spring fixing rod, for applying tension to the scraper; the elastic element is a tension spring or a compression spring, the wire diameter of the elastic element is 2-3mm, the diameter is 20-35mm, and the elastic deformation is in the range of 15%-25%.

2. The pyrolysis method according to claim 1, characterized in that: The compression spring has a wire diameter of 2-3mm, a diameter of 20-35mm, and an elastic deformation in the range of 20-25%.

3. The pyrolysis method according to any one of claims 1-2, characterized in that: The end of the scraper that contacts the inner wall of the pyrolysis reactor is fan-shaped, and the radius R of the fan-shaped area is 0.5-1 times the thickness of the scraper.

4. The pyrolysis method according to any one of claims 1-2, characterized in that: The waste polymer materials mentioned are selected from one or more types of waste tires and synthetic fiber clothing waste.

5. The pyrolysis method according to any one of claims 1-2, characterized in that: The waste polymer material mentioned is waste rubber.

6. The pyrolysis method according to any one of claims 1-2, characterized in that: The pyrolysis temperature is 400℃-500℃.

7. The pyrolysis method according to any one of claims 1-2, characterized in that: The waste polymer materials are subjected to pretreatment of crushing and / or dehydration before being fed into the pyrolysis reactor.

8. The pyrolysis method according to claim 6, characterized in that: The size of the crushed waste polymer material is no greater than 10 mm.

9. The pyrolysis method according to any one of claims 1-2, characterized in that: The pyrolysis method includes multiple pyrolysis reactors connected in series and / or in parallel.

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