Multistage catalytic pyrolysis device for polyolefin waste plastics

Abstract

The utility model discloses a multi-stage catalytic pyrolysis device for polyolefin waste plastics. The multi-stage catalytic pyrolysis device comprises a pretreatment system, a multi-stage pyrolysis reaction system and a post-treatment system which are connected in sequence, the waste plastics are sorted and pretreated by the pretreatment system, then enter the multi-stage pyrolytic reaction system for directional preparation to obtain plastic monomers, are separated by the product separation system, and then are treated by the post-treatment system to obtain ethylene and propylene. The pyrolysis device is used for directionally preparing ethylene and propylene through multi-stage catalytic pyrolysis of polyolefin waste plastics, realizes all-component clean high-valued integrated utilization of solid-liquid-gas pyrolysis products of the waste plastics, ensures the feasibility and operability of a technology during amplification of a chemical cycle process of the waste plastics, is beneficial to industrialization, and has a wide application prospect. The device is an integrated device for chemical circulation and efficient utilization of waste plastics. Meanwhile, the pyrolysis device prevents pollutant impurities in the waste plastics from polluting and inactivating the catalyst, improves the yield of ethylene and propylene, and reduces the treatment cost of the catalyst.

Description

Technical Field

[0001] The utility model belongs to the technical field of solid waste recovery devices, and in particular relates to a device for directional preparation of ethylene and propylene through multi-stage catalytic pyrolysis of polyolefin waste plastics. Background Art

[0002] The resource recycling and reuse of urban organic solid waste is of great significance to my country's construction of a green, low-carbon, circular development economic system, solving my country's resource and environmental problems, and achieving the "dual carbon goals" of carbon peak and carbon neutrality. For a long time, the recycling and environmentally friendly treatment of low-residual value waste plastics has been a pain point and missing point in the industry.

[0003] The chemical recycling technology of waste plastics uses the principle of thermal cracking to convert high molecular compounds (waste tires, waste plastics, waste rubber, etc.) into a variety of low molecular compounds under an inert atmosphere, and combines the selective regulation of catalysts to prepare new plastic monomers in a directional manner to achieve the homogenization cycle of waste plastics. Compared with traditional treatment technologies such as landfill, regeneration granulation and incineration, the chemical recycling technology of waste plastics can not only treat mixed dirty plastics and reduce environmental pollution during the treatment process, but also convert them into new plastic monomers to achieve the effects of cleaning, high value and recycling, reduce the consumption of fossil resources in the plastic production process, and effectively reduce carbon emissions.

[0004] Driven by the construction of waste-free cities, garbage classification and resource disposal, the chemical recycling of waste plastics meets the social needs of global energy structure adjustment and environmental protection. It is an effective means to solve the problem of plastic pollution and an effective supplement to the physical recycling of plastics. It is of great significance to the realization of a plastic circular economy. Utility Model Content

[0005] In order to improve the deficiencies of the prior art, the utility model provides a multi-stage catalytic pyrolysis device for polyolefin waste plastics, which can directionally prepare ethylene and propylene, realize the clean and high-value integrated utilization of all components of the solid, liquid and gas pyrolysis products of waste plastics, and ensure the feasibility and operability of the waste plastic chemical recycling process when it is scaled up.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A multi-stage catalytic pyrolysis device for polyolefin waste plastics comprises a pretreatment system, a multi-stage pyrolysis reaction system and a post-treatment system connected in sequence; the waste plastics are sorted and pre-treated by the pretreatment system, then enter the multi-stage pyrolysis reaction system for directional preparation to obtain plastic monomers, which are separated by a product separation system and then processed by a post-treatment system to obtain ethylene and propylene.

[0008] In one embodiment of the utility model, the pretreatment system includes a plastic sorter and a plastic extrusion crusher. A waste plastic inlet is opened on the top of the plastic sorter. The sorted waste plastic enters the plastic extrusion crusher and is then sent into the multi-stage pyrolysis reaction system through an extrusion conveying screw.

[0009] In one embodiment of the utility model, a carrier gas input port is provided above the plastic extrusion crusher.

[0010] In one embodiment of the utility model, the multi-stage pyrolysis reaction system includes a first pyrolysis system, a second pyrolysis system and a third pyrolysis system connected in sequence; the first pyrolysis system is connected to a plastic extrusion crusher through an extrusion conveying screw, the first pyrolysis system is connected to the second pyrolysis system through a first gas conveying pipeline, and the second pyrolysis system is connected to the third pyrolysis system through a second gas conveying pipeline.

[0011] In one embodiment of the utility model, the first pyrolysis system is a rotary kiln pyrolysis system; the second pyrolysis system is a two-stage fixed bed pyrolysis system, and a molecular sieve-based pyrolysis catalyst is placed in the middle; the third pyrolysis system is a three-stage fixed bed pyrolysis system, and a molecular sieve-based pyrolysis catalyst is placed in the middle.

[0012] In one embodiment of the utility model, the lower outlet of the rotary kiln pyrolysis system is connected to a pyrolysis carbon slag storage tank for containing the pyrolysis product residue.

[0013] In one embodiment of the present invention, the outlet of the third pyrolysis system is communicated with the inlet of the product separation system.

[0014] In one embodiment of the present invention, the first outlet of the product separation system located on the upper side is connected to the ethylene / propylene product storage tank through the first gas filtration system.

[0015] In one embodiment of the utility model, a second outlet at the bottom of the product separation system is connected to a second gas filtration system, and the second gas filtration system is connected to the inlet of the third pyrolysis system. The heavy components at the lower end of the product separation system are filtered by the second gas filtration system and circulated to the third pyrolysis system.

[0016] In one embodiment of the utility model, the third outlet of the product separation system located at the top is connected to the CO and H2 rich combustion energy supply system, and the CO / H2 / CH4 ultra-light components separated from the upper layer enter the combustion energy supply system; a vacuum pump is also arranged between the third outlet and the CO and H2 rich combustion energy supply system.

[0017] Beneficial effects of the utility model:

[0018] The pyrolysis device provided by the utility model is used for the multi-stage catalytic pyrolysis of polyolefin waste plastics to prepare ethylene and propylene in a directional manner. The device structure realizes the clean and high-value integrated utilization of all components of the solid, liquid and gas pyrolysis products of the waste plastics, ensures the feasibility and operability of the technology when the chemical recycling process of the waste plastics is enlarged, is conducive to industrialization, and is an integrated device for efficient utilization of the chemical recycling of waste plastics. At the same time, the pyrolysis device avoids the contamination and deactivation of the catalyst by pollutants and impurities in the waste plastics, improves the yield of ethylene and propylene, and reduces the cost of catalyst treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a multi-stage catalytic pyrolysis device for polyolefin waste plastics;

[0020] Figure 2 It is a schematic diagram of the process flow of multi-stage catalytic pyrolysis of polyolefin waste plastics. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be interpreted as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope of protection of the present invention.

[0022] like Figure 1 As shown, the utility model provides a multi-stage catalytic pyrolysis device for polyolefin waste plastics, comprising a pretreatment system, a multi-stage pyrolysis reaction system, a product separation system and a post-treatment system connected in sequence; the waste plastics are sorted and pre-treated by the pretreatment system, and then enter the multi-stage pyrolysis reaction system for directional preparation to obtain plastic monomers, which are separated by the product separation system and then processed by the post-treatment system to obtain ethylene and propylene.

[0023] like Figure 1 As shown, the pretreatment system includes a plastic sorter 1 and a plastic extrusion crusher 2. A waste plastic inlet is opened on the top of the plastic sorter 1. The sorted waste plastic enters the plastic extrusion crusher 2 and is then sent to the multi-stage pyrolysis reaction system through the extrusion conveying screw 3.

[0024] Preferably, a nitrogen inlet is provided on the top of the plastic extrusion crusher 2, and nitrogen is input as a carrier gas during use.

[0025] According to the utility model, the multi-stage pyrolysis reaction system includes a first pyrolysis system 4, a second pyrolysis system 6 and a third pyrolysis system 8 connected in sequence. The first pyrolysis system 4 is connected to the plastic extrusion crusher 2 through an extrusion conveying screw 3, the first pyrolysis system 4 is connected to the second pyrolysis system 6 through a first gas conveying pipeline 5, and the second pyrolysis system 6 is connected to the third pyrolysis system 8 through a second gas conveying pipeline 7.

[0026] Specifically, the first pyrolysis system 4 is a rotary kiln pyrolysis system. The lower outlet of the rotary kiln pyrolysis system is connected to a pyrolysis carbon residue storage tank 13 for storing the residue of the pyrolysis product.

[0027] Specifically, the second pyrolysis system 6 is a two-stage fixed-bed pyrolysis system, and the third pyrolysis system 8 is a three-stage fixed-bed pyrolysis system. Molecular sieve-based pyrolysis catalysts are placed between the second pyrolysis system 6 and the third pyrolysis system 8 .

[0028] The outlet of the third pyrolysis system 8 is connected to the inlet of the product separation system 9. The product separation system 9 has at least three outlets, and the first outlet located on the upper side is connected to the ethylene / propylene product storage tank 15 through the first gas filtration system 10. The second outlet located at the bottom of the product separation system 9 is connected to the second gas filtration system 14, and the second gas filtration system 14 is connected to the inlet of the third pyrolysis system 8. The heavy components at the lower end of the product separation system 9 are filtered by the second gas filtration system 14 and circulated to the third pyrolysis system 8 for re-pyrolysis. The third outlet at the top of the product separation system 9 is connected to the CO and H2-rich combustion energy supply system 12, and the ultra-light components of CO / H2 / CH4 separated from the upper layer enter the combustion energy supply system.

[0029] Preferably, a vacuum pump 11 is further provided between the third outlet and the CO and H2 rich combustion energy supply system 12 .

[0030] In the present invention, the product separation system 9, the first gas filtration system 10, the ethylene / propylene product storage tank 15, the second gas filtration system 14, and the CO and H2-rich combustion energy supply system 12 are collectively referred to as a post-processing system.

[0031] The processing technology of the utility model is as follows:

[0032] like Figure 1 As shown, after the waste plastics are sorted and pretreated by the pretreatment system, they enter the multi-stage pyrolysis reaction system, in which the first stage of pyrolysis uses a low-cost and widely adaptable clay catalyst for in-situ pyrolysis, and the initial pyrolysis product enters the subsequent second stage upgrading and third stage recombination with the carrier gas, avoiding the contamination of the second upgrading and third recombination stage catalysts by pollutants and impurities in the waste plastics. The second and third stages use modified molecular sieve catalysts, and the modified molecular sieves are upgraded and the modified molecular sieves are recombined to produce the initial pyrolysis products, and new plastic monomers are prepared in a directional manner. The multi-stage pyrolysis, upgrading and recombination uses modified molecular sieve catalysts. After the first stage of in-situ initial pyrolysis treatment, the deactivation of the modified molecular sieve catalyst can be effectively avoided, reducing the processing cost.

[0033] The above describes the implementation methods of the present invention. However, the present invention is not limited to the above implementation methods. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-stage catalytic pyrolysis device for polyolefin waste plastics, characterized in that: It includes a pre-treatment system, a multi-stage pyrolysis reaction system and a post-treatment system connected in sequence; The pretreatment system comprises a plastic sorting machine (1) and a plastic extrusion crusher (2). A waste plastic inlet is provided on the top of the plastic sorting machine (1). The sorted waste plastic enters the plastic extrusion crusher (2) and is then fed into a multi-stage pyrolysis reaction system via an extrusion conveying screw (3). The multi-stage pyrolysis reaction system comprises a first pyrolysis system (4), a second pyrolysis system (6) and a third pyrolysis system (8) which are connected in sequence; the first pyrolysis system (4) is connected to the outlet of a plastic extrusion crusher (2) via an extrusion conveying screw (3), the first pyrolysis system (4) is connected to the second pyrolysis system (6) via a first gas conveying pipeline (5), and the second pyrolysis system (6) is connected to the third pyrolysis system (8) via a second gas conveying pipeline (7).

2. The multi-stage catalytic pyrolysis device for polyolefin waste plastics according to claim 1, characterized in that: The first pyrolysis system (4) is a rotary kiln pyrolysis system; the second pyrolysis system (6) is a two-stage fixed bed pyrolysis system; and the third pyrolysis system (8) is a three-stage fixed bed pyrolysis system.

3. The multi-stage catalytic pyrolysis device for polyolefin waste plastics according to claim 2, characterized in that: The lower outlet of the rotary kiln type pyrolysis system is connected to a pyrolysis carbon slag storage tank (13) configured to contain the pyrolysis product residue.

4. The multi-stage catalytic pyrolysis device for polyolefin waste plastics according to claim 2, characterized in that: The outlet of the third pyrolysis system (8) is communicated with the inlet of the product separation system (9) of the post-processing system.

5. The multi-stage catalytic pyrolysis device for polyolefin waste plastics according to claim 4, characterized in that: The first outlet located at the top of the product separation system (9) is connected to the ethylene / propylene product storage tank (15) through the first gas filtration system (10).

6. The multi-stage catalytic pyrolysis device for polyolefin waste plastics according to claim 4, characterized in that: A second outlet at the bottom of the product separation system (9) is connected to a second gas filtration system (14), and the outlet of the second gas filtration system (14) is connected to the inlet of the third pyrolysis system (8), so that the heavy components at the lower end of the product separation system (9) are filtered by the second gas filtration system (14) and then circulated to the third pyrolysis system (8).

7. The multi-stage catalytic pyrolysis device for polyolefin waste plastics according to claim 6, characterized in that: The third outlet located above the product separation system (9) is connected to the CO and H2-rich combustion energy supply system (12), and the CO / H2 / CH4 ultra-light components separated from the upper layer enter the combustion energy supply system; a vacuum pump (11) is also provided between the third outlet and the CO and H2-rich combustion energy supply system (12).

8. The multi-stage catalytic pyrolysis device for polyolefin waste plastics according to claim 1, characterized in that: A carrier gas input port is provided above the plastic extrusion crusher (2).

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