Self-sustaining waste anaerobic pyrolysis volume reduction treatment device and method

Abstract

The application discloses a self-sustaining waste anaerobic pyrolysis volume reduction treatment device and method, which comprises a pyrolysis chamber and a burning chamber completely isolated by a high-temperature-resistant and corrosion-resistant composite material partition plate, and the pyrolysis chamber and the burning chamber are arranged in parallel and are communicated by a pyrolysis gas conveying pipeline. Air and fuel are continuously supplied into the burning chamber and ignited, the heat released by the fuel combustion is transmitted to the pyrolysis chamber through the partition plate, and is used for heating materials in the pyrolysis chamber to start pyrolysis; after the materials are stably pyrolyzed, the fuel supply is stopped, the material pyrolysis gas is used as fuel to maintain the burning chamber combustion and heat release, and the material pyrolysis in the pyrolysis chamber is maintained by the heat released by the combustion, so that the self-sustaining anaerobic pyrolysis stable operation is realized. The application overcomes the inherent defects of the prior art, and the grate at the bottom of the pyrolysis chamber is not needed, thereby providing a new solution for the treatment of plastic solid wastes, especially low-emission combustible solid wastes.

Description

Technical Field

[0001] This invention belongs to the field of waste thermal treatment technology, and particularly relates to a self-sustaining waste anaerobic pyrolysis volume reduction treatment device and method. Background Technology

[0002] The nuclear industry generates a large amount of radioactive waste during operation and decommissioning, of which low-level radioactive combustible solid waste (hereinafter referred to as low-level combustible solid waste) can account for up to 50%, such as plastics, rubber, and textiles. This waste requires inorganic and volume-reducing treatment before final disposal to save on disposal costs and improve the stability and safety of long-term disposal. Incineration is the primary method for treating low-level combustible solid waste and is widely used in my country and Western countries. Initially, waste was treated using oxygen incineration technology; however, oxygen incineration has prominent problems such as high pollutant levels, large fly ash volumes, and severe radionuclide volatilization. Subsequently, oxygen-controlled combustion technology was developed. Currently, the most advanced waste incineration technology is pyrolysis-incineration technology, belonging to the third generation of incineration technology. Among them, the anoxic pyrolysis-incineration technology, which is mainly developed in my country, has achieved good treatment results for combustible solid waste with a plastic content as high as 60%, and its main key technical indicators are still at the international leading level.

[0003] The working principle of anaerobic pyrolysis-incineration technology is as follows: materials are added to the pyrolysis furnace in batches and piled on the grate. Air at a concentration far below the stoichiometric ratio is introduced into the furnace via a blower. After being reorganized by the grate, the air is supplied to the material layer. Initially, external energy is used to ignite the bottom layer of materials. Once a stable char layer forms at the bottom, external energy is no longer needed. Instead, the heat generated by the combustion of the char layer heats the upper layer of materials. The upper layer of materials, upon heating, undergoes decomposition, converting into small-molecule combustible gas, i.e., pyrolysis gas. This pyrolysis gas exits the pyrolysis furnace, is premixed with sufficient air, and then enters the incineration chamber for oxygen-enriched combustion. Based on the inherent principle of anaerobic pyrolysis-incineration technology—that the heat required for material pyrolysis comes from the combustion process of the bottom material—a certain amount of air needs to be introduced into the material layer within the furnace to maintain the combustion of the bottom material. Therefore, anaerobic pyrolysis incinerators are equipped with a grate at the bottom. It is precisely this bottom grate design that makes anaerobic pyrolysis-incineration technology difficult to process plastic waste. This is because most plastic waste is thermoplastic, which melts when heated and has high fluidity. This means the molten plastic leaks through the grate's vents before reacting, making it difficult to form a stable char layer. Consequently, the heat required for the pyrolysis of the upper material cannot be generated, and the self-sustaining anaerobic pyrolysis process cannot occur. Furthermore, the molten plastic and its charring can clog the grate, preventing air from entering above the grate and contacting the material, thus interrupting the reaction. In addition, the incomplete leakage of waste also increases the loss on ignition of the incinerator ash.

[0004] With the rapid development of the nuclear industry, the proportion of plastic waste in radioactive combustible solid waste has increased significantly, especially in radioactive combustible solid waste generated by nuclear power plants, where plastic waste accounts for more than 80% of the total waste, sometimes even approaching 100%, far exceeding the design specifications of existing pyrolysis incineration technologies. Due to the inherent limitations of existing anaerobic pyrolysis incineration technology in terms of process and equipment, it is difficult to effectively treat plastic waste. Therefore, there is an urgent need to develop a new thermal volume reduction technology to avoid the drawbacks of existing anaerobic pyrolysis incineration technology, so as to achieve efficient, safe, and clean treatment of waste with high plastic content or even pure plastic waste. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a self-sustaining anaerobic pyrolysis volume reduction treatment device and method for waste, offering a solution for the current treatment of nuclear power waste, which is primarily composed of plastic waste. This invention creatively improves the design of the pyrolysis chamber and incineration chamber of existing anoxic pyrolysis incinerators. Instead of using the combustion of pyrolysis gas in the incineration chamber to indirectly provide heat for the pyrolysis of materials in the pyrolysis chamber, as is done in existing anoxic pyrolysis incineration processes where the combustion of lower-layer materials directly provides heat for the pyrolysis of upper-layer materials, this invention simplifies the pyrolysis process, eliminates the need for air supply to the pyrolysis chamber, truly achieves anaerobic pyrolysis of materials, and eliminates the need for external heating after the device is operating stably. This also eliminates the need for a grate, fundamentally avoiding material leakage problems and improving waste adaptability.

[0006] In a first aspect, the present invention discloses a self-sustaining anaerobic pyrolysis volume reduction treatment device for waste. The device includes an upper chamber and a lower chamber, which are completely separated by a high-temperature and corrosion-resistant composite material partition. The upper chamber is a pyrolysis chamber, in which the material is heated to the pyrolysis temperature and begins to decompose, generating pyrolysis gas. The lower chamber is an incineration chamber, in which the heat released by combustion heats the material in the pyrolysis chamber through the partition. The pyrolysis chamber and the incineration chamber are connected by a pyrolysis gas conveying pipe, through which the pyrolysis gas generated in the pyrolysis chamber enters the incineration chamber.

[0007] Furthermore, the pyrolysis chamber is equipped with a screw conveyor mechanism for conveying the pyrolysis ash formed after the material is pyrolyzed to the ash discharge port.

[0008] Furthermore, the pyrolysis chamber and the spiral conveyor mechanism are both made of high-temperature and corrosion-resistant steel, and are equipped with cooling water jackets on the outside.

[0009] Furthermore, the combustion chamber is provided with a fuel inlet and an air inlet for supplying fuel and air into the combustion chamber, respectively.

[0010] Furthermore, the incineration chamber is provided with a flue gas outlet for the outflow of flue gas generated during the incineration process.

[0011] Furthermore, the incineration chamber is made of high-temperature and corrosion-resistant steel, and the inner walls of the incineration chamber are lined with refractory bricks.

[0012] Furthermore, a feed inlet is provided above the pyrolysis chamber, and an upper insert plate and a lower insert plate are provided sequentially from top to bottom on the feed pipe between the feed inlet and the pyrolysis chamber to ensure that the pyrolysis chamber is always in a sealed state when feeding.

[0013] Furthermore, a spiral feeding mechanism or conveyor belt is provided between the feed inlet and the upper insert plate to transport the material to the top of the upper insert plate.

[0014] Secondly, the present invention also discloses a self-sustaining anaerobic pyrolysis volume reduction treatment method for waste. This method uses the self-sustaining anaerobic pyrolysis volume reduction treatment device described in the first aspect of the present invention to perform pyrolysis volume reduction treatment, and includes the following steps: S1. Feeding Add materials to the pyrolysis chamber; S2. Oven Air and fuel are continuously supplied to the combustion chamber and ignited. The heat released by the combustion of fuel preheats the combustion chamber. Heat is transferred to the pyrolysis chamber through the partition between the combustion chamber and the pyrolysis chamber to heat the materials in the pyrolysis chamber. S3. Stable operation When the temperature inside the pyrolysis chamber rises to the pyrolysis temperature, the fuel supply to the combustion chamber is gradually reduced; once the temperature inside the pyrolysis chamber stabilizes at the pyrolysis temperature, the fuel supply to the combustion chamber is stopped; the pyrolysis gas generated by the pyrolysis of the material inside the pyrolysis chamber enters the combustion chamber through the pyrolysis gas conveying pipeline, and the pyrolysis gas is burned as fuel in the combustion chamber to release heat and maintain the pyrolysis of the material inside the pyrolysis chamber; during this period, the material is continuously fed into the pyrolysis chamber to ensure the stable operation of the self-sustaining pyrolysis system; S4. Shutdown Stop feeding materials into the pyrolysis chamber and supply fuel to the combustion chamber again. The heat released by the fuel combustion sustains the pyrolysis of the remaining materials in the pyrolysis chamber. After all the materials in the pyrolysis chamber have been pyrolyzed, stop supplying fuel to complete the pyrolysis volume reduction process.

[0015] Furthermore, the pyrolysis temperature is 400~700℃.

[0016] This invention provides a self-sustaining anaerobic pyrolysis and volume reduction treatment device and method for waste. Through innovations in device structure, principle, and process, this invention enables self-sustaining anaerobic pyrolysis of waste, especially plastic waste. Compared to existing anoxic pyrolysis-incineration technologies, in this invention, the heat required for material pyrolysis comes from the heat released by the combustion of pyrolysis gases in the incineration chamber. The heat released by the combustion of pyrolysis gases indirectly heats the material through the partition between the pyrolysis chamber and the incineration chamber. The material undergoes anaerobic pyrolysis in the pyrolysis chamber, therefore, air does not need to be introduced into the pyrolysis chamber. In contrast, existing anoxic pyrolysis-incineration technologies rely entirely on the heat released by the combustion of the bottom char layer, thus requiring a continuous supply of air to the pyrolysis furnace. This invention overcomes the inherent defects of existing technologies and provides a new solution for the treatment of low-level radioactive combustible solid waste generated by nuclear power plants and other nuclear-related entities. Of course, this invention is also fully applicable to the treatment of waste in non-radioactive fields, especially plastic waste. Therefore, compared with existing technologies, this invention has at least the following beneficial effects: (1) The self-sustaining anaerobic pyrolysis volume reduction treatment device and method of the present invention does not require the installation of a grate in the pyrolysis chamber, thus fundamentally avoiding the problem of heat melting and leakage of plastic waste, reducing the heat loss rate of solid residues, and improving the waste volume reduction ratio.

[0017] (2) In the self-sustaining anaerobic pyrolysis volume reduction treatment device and method of the present invention, the heat supplied for the pyrolysis of the material comes entirely from the heat released by combustion in the incinerator, rather than from the heat released by the char layer formed at the bottom of the material. Therefore, it overcomes the inherent defect of existing anaerobic pyrolysis incineration technology that requires a stable char layer to be formed at the bottom of the material before the pyrolysis process can be stably operated. Especially for materials such as plastic waste that are difficult to form a char layer, it greatly reduces the difficulty of starting up the pyrolysis of the material.

[0018] (3) The self-sustaining anaerobic pyrolysis volume reduction treatment device and method of the present invention can maintain the stable operation of the pyrolysis process without the need to introduce air into the pyrolysis chamber, thus realizing anaerobic pyrolysis. Therefore, the material is hardly disturbed by the airflow, and the amount of fly ash is significantly reduced. In particular, it avoids the radioactive nuclides from entering the flue gas through the fly ash carrier when pyrolyzing low-level combustible solid waste, thereby reducing the difficulty of flue gas purification and improving the nuclide retention rate.

[0019] (4) After the self-sustaining anaerobic pyrolysis volume reduction treatment device and method of the present invention is running stably, there is no need to maintain the fuel supply. The pyrolysis gas generated by the pyrolysis of the material is used as fuel and transported from the pyrolysis chamber to the incineration chamber for combustion and heat release. The heat released by combustion provides heat for the pyrolysis of the material in the pyrolysis chamber through the partition. That is, the heat required for the pyrolysis of the material in the pyrolysis chamber is maintained by the heat released by the combustion of the pyrolysis gas entering the incineration chamber. At the same time, the combustion process in the incineration chamber is maintained by the pyrolysis gas generated in the pyrolysis chamber, forming a stable self-sustaining process. This realizes the self-sustaining anaerobic pyrolysis volume reduction treatment of waste, reduces fuel energy consumption, and also reduces waste disposal costs.

[0020] (5) The self-sustaining anaerobic pyrolysis volume reduction treatment device and method of the present invention has outstanding waste adaptability and can treat waste with high plastic content or even pure plastic. At the same time, it maintains significant advantages in terms of radionuclide retention rate, waste volume reduction ratio and heat loss rate, and is therefore applicable to the treatment of almost all organic solid waste. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the self-sustaining anaerobic pyrolysis volume reduction treatment device for waste according to the present invention.

[0023] Explanation of reference numerals in the attached drawings: 1. Self-sustaining anaerobic pyrolysis volume reduction treatment device for waste; 2. Pyrolysis chamber; 3. Incineration chamber; 4. Baffle plate; 5. Material; 6. Pyrolysis gas conveying pipeline; 7. Screw conveying mechanism; 8. Ash discharge port; 9. Ash bucket; 10. Ball valve; 11. Cooling water inlet; 12. Cooling water outlet; 13. Fuel inlet; 14. Air inlet; 15. Flue gas outlet; 16. Exhaust fan; 17. Feed inlet; 18. Feeding pipeline; 19. Upper insert plate; 20. Lower insert plate; 21. Screw feeding mechanism; 22. Temperature measuring instrument. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] Unless otherwise specified, all temperatures mentioned herein are in degrees Celsius, and the preferred embodiments can be freely combined as needed. Those skilled in the art will understand that the data and parameters described in the examples are merely exemplary and do not constitute a limitation of the invention. All components used in the following examples and comparative examples are compounds known in the art, and all equipment used is equipment publicly known in the art. All components and equipment used in this invention can be obtained commercially or prepared using known techniques.

[0026] This invention provides a self-sustaining anaerobic pyrolysis volume reduction treatment device 1 for waste. The device includes an upper chamber and a lower chamber, which are completely separated by a high-temperature and corrosion-resistant composite material partition 4. The upper chamber is a pyrolysis chamber 2, where the material 5 is heated to the pyrolysis temperature and begins to decompose, generating pyrolysis gas. The lower chamber is an incineration chamber 3, where the heat released from combustion heats the material 5 in the pyrolysis chamber 2 through the partition 4. The pyrolysis chamber 2 and the incineration chamber 3 are connected by a pyrolysis gas conveying pipe 6, through which the pyrolysis gas generated in the pyrolysis chamber 2 enters the incineration chamber 3.

[0027] The pyrolysis chamber 2 of this invention is equipped with a screw conveyor mechanism 7, which transports the pyrolysis ash formed after the material 5 is pyrolyzed to the ash discharge port 8 and falls into the ash bucket 9, which is fixedly connected to the ash discharge port 8. Furthermore, the screw conveyor mechanism 7 can also evenly distribute the material at the bottom of the pyrolysis chamber 2, ensuring uniform pyrolysis. The pyrolysis chamber 2 and the screw conveyor mechanism 7 are preferably made of high-temperature and corrosion-resistant steel. To prevent overheating of the pyrolysis chamber 2 and the screw conveyor mechanism 7, a cooling water jacket can be installed outside them. Circulating cooling water enters the cooling water jacket through the cooling water inlet 11 via the ball valve 10 and exits through the cooling water outlet 12. The pyrolysis chamber 2 of this invention is also equipped with a thermometer 22 for monitoring the temperature of the material layer inside the pyrolysis chamber 2.

[0028] The combustion chamber 3 of this invention is provided with a fuel inlet 13 and an air inlet 14 for supplying fuel and air to the combustion chamber 3 respectively. Diesel fuel, which has relatively high combustion efficiency, can be selected as the fuel in this invention. The fuel passes sequentially through a check valve and a ball valve along the delivery pipeline, and enters the combustion chamber 3 through the fuel inlet 13, where it is ignited by the ignition system. The combustion chamber 3 of this invention also has a flue gas outlet 15. Under the action of the induced draft fan 16 at the end of the device, the flue gas generated during combustion flows out of the combustion chamber 3 from the flue gas outlet 15. Under the action of the induced draft fan 16, a negative pressure condition is formed in the combustion chamber 3. The pyrolysis gas in the pyrolysis chamber 2 flows out of the pyrolysis chamber 2 along the pyrolysis gas delivery pipeline 6 under the action of the pressure difference, and mixes with the air flowing in through the air inlet 14 in the pyrolysis gas delivery pipeline 6 before entering the combustion chamber 3 together for combustion. Preferably, a butterfly valve is installed on the air delivery pipeline to control the opening and closing of the air inlet 14. Once the pyrolysis of material 5 in pyrolysis chamber 2 has stabilized, fuel supply to incineration chamber 3 is stopped. At this point, the heat required for the pyrolysis of material 5 in pyrolysis chamber 2 is maintained by the heat released from the combustion of pyrolysis gas entering incineration chamber 3. Simultaneously, the combustion process in incineration chamber 3 is maintained by the pyrolysis gas generated in pyrolysis chamber 2, forming a stable, self-sustaining pyrolysis process. Throughout the entire process, no air supply is required in pyrolysis chamber 2, and material 5 undergoes pyrolysis under anaerobic conditions. This achieves self-sustaining anaerobic pyrolysis of the material, unlike the existing oxygen-deficient pyrolysis incineration process. The incineration chamber 3 of this invention is preferably made of high-temperature and corrosion-resistant steel. To prevent overheating of the incineration chamber 3, refractory bricks are preferably lined the inner wall of the incineration chamber 3.

[0029] The present invention provides a feed inlet 17 above the pyrolysis chamber 2 for feeding materials into the pyrolysis chamber 2. A feed pipe 18 between the feed inlet 17 and the pyrolysis chamber 2 is Z-shaped, and an upper insert plate 19 and a lower insert plate 20 are sequentially arranged from top to bottom on the feed pipe 18 to ensure that the pyrolysis chamber 2 remains sealed during feeding. A spiral feeding mechanism 21 is provided on the horizontal section of the feed pipe between the feed inlet 17 and the upper insert plate 19 to uniformly transport the material fed from the feed inlet 17 to above the upper insert plate 19. During the feeding operation, the material is fed into the feed port 17, and the screw feed mechanism 21 is started at the same time to transport the material to the upper insert plate 19. Under the action of gravity, the material falls onto the upper insert plate 19. While keeping the lower insert plate 20 in the closed state, the upper insert plate 19 is opened, and the material falls between the upper insert plate 19 and the lower insert plate 20. The upper insert plate 19 is closed, the lower insert plate 20 is opened, and the material falls into the bottom of the pyrolysis chamber 2. The lower insert plate 20 is then closed, thus completing the material feeding operation.

[0030] It is understandable that, in order to keep the pyrolysis chamber 2 in a sealed state, the upper plate 19 and the lower plate 20 cannot be opened simultaneously, and at least one plate should always be closed. Of course, in order to avoid material jamming on the screw feed mechanism 21, the screw feed mechanism can also be replaced with a conveyor belt mechanism. After the material is fed into the feed port 17, the conveyor belt mechanism is started at the same time to transport the material to the upper plate 19.

[0031] The flue gas generated during the incineration process in the incineration chamber 3 can flow out from the flue gas outlet 15. Preferably, it is treated in sequence by dust removal, cooling, filtration, acid gas absorption, demisting, and filtration before being discharged into the environment.

[0032] After the volume reduction treatment and furnace shutdown cooling are completed, the spiral conveyor mechanism 7 in the pyrolysis chamber 2 is started to transport the pyrolysis ash formed after the waste pyrolysis to the ash discharge port 8. The ash discharge port 8 is opened and the pyrolysis ash falls into the ash bucket 9 which is fixedly connected to the ash discharge port 8. After the ash discharge port 8 is closed, the ash bucket 9 is removed.

[0033] The present invention also provides a self-sustaining anaerobic pyrolysis volume reduction treatment method for waste. This method uses the self-sustaining anaerobic pyrolysis volume reduction treatment device 1 described in the first aspect of the present invention to perform pyrolysis volume reduction treatment, and includes the following steps: S1. Feeding Material 5 is added into pyrolysis chamber 2; S2. Oven Air and fuel are continuously supplied to the combustion chamber 3 and ignited. The heat released by the combustion of fuel preheats the combustion chamber 3. Heat is transferred to the pyrolysis chamber 2 through the partition 4 between the combustion chamber 3 and the pyrolysis chamber 2 to heat the material 5 in the pyrolysis chamber 2. S3. Stable operation When the temperature inside pyrolysis chamber 2 rises to the pyrolysis temperature, the fuel supply to combustion chamber 3 is gradually reduced. After the temperature inside pyrolysis chamber 2 stabilizes at the pyrolysis temperature, the material 5 inside pyrolysis chamber 2 has begun stable pyrolysis, at which point the fuel supply to combustion chamber 3 is stopped. The pyrolysis gas generated by the pyrolysis of material 5 inside pyrolysis chamber 2 enters combustion chamber 3 through the pyrolysis gas conveying pipe 6. The pyrolysis gas is used as fuel to burn and release heat in combustion chamber 3, maintaining the pyrolysis of material 5 inside pyrolysis chamber 2. The pyrolysis gas generated by pyrolysis enters combustion chamber 3 to maintain the continued combustion and heat release in combustion chamber 3. During this period, material is continuously fed into pyrolysis chamber 2 to ensure the stable operation of the self-sustaining pyrolysis. The pyrolysis temperature varies depending on the type of material, and is usually 400~700℃. S4. Shutdown Stop feeding material into pyrolysis chamber 2, and resume supplying fuel to combustion chamber 3. The heat released by fuel combustion sustains the pyrolysis of the remaining material in pyrolysis chamber 2. Continue supplying fuel until all material 5 in pyrolysis chamber 2 has been pyrolyzed, then stop supplying fuel to complete the pyrolysis volume reduction process. When using diesel fuel, continuous fuel supply for 20-40 minutes is usually sufficient to complete the pyrolysis of the remaining material, at which point fuel supply can be stopped, and the system can be allowed to cool down.

[0034] The present invention will now be described in more detail with reference to exemplary embodiments. The following embodiments or experimental data are intended to illustrate the present invention by way of example, and those skilled in the art should understand that the present invention is not limited to these embodiments or experimental data.

[0035] Example 1 The self-sustaining anaerobic pyrolysis volume reduction treatment device of the present invention is used to perform pyrolysis volume reduction treatment on polyethylene solid waste.

[0036] S1. Feeding Material is fed into the inlet 17, and the screw feeding mechanism 21 is activated to convey the material to the upper plate 19. Under the action of gravity, the material falls onto the upper plate 19. While keeping the lower plate 20 closed, the upper plate 19 is opened, and the material falls between the upper plate 19 and the lower plate 20. The upper plate 19 is closed, and the lower plate 20 is opened, and the material falls to the bottom of the pyrolysis chamber 2. The lower plate 20 is then closed. The screw conveying mechanism 7 in the pyrolysis chamber 2 is activated to distribute the material evenly at the bottom of the pyrolysis chamber 2.

[0037] S2. Oven Open the butterfly valve on the air delivery pipeline, open the induced draft fan 16 at the end of the system and the blower at the front end of the air delivery pipeline, and supply air to the combustion chamber 3 through the air inlet 14; The ignition system inside the combustion chamber 3 is started, and the check valve and ball valve on the fuel delivery pipeline are opened. Diesel fuel is supplied to the combustion chamber 3 through the fuel inlet 13, and the fuel nozzle is ignited by the ignition system. The heat released by the combustion of diesel fuel preheats the combustion chamber 3 and transfers heat to the pyrolysis chamber 2 through the partition 4 between the combustion chamber 3 and the pyrolysis chamber 2, which is used to heat the material 5 inside the pyrolysis chamber 2.

[0038] S3. Stable operation Open the cooling water inlet 11, cooling water outlet 12 and cooling water circulation system, observe the reading of the material layer thermometer 22 in the pyrolysis chamber 2, when the material layer temperature rises to 400℃, gradually reduce the oil supply to the combustion chamber 3, the material layer temperature in the pyrolysis chamber 2 continues to rise and stabilizes at about 470℃, at this time the material 5 in the pyrolysis chamber 2 has begun to stably decompose, stop supplying oil to the combustion chamber 3; Under the action of the induced draft fan 16, a negative pressure condition is formed in the combustion chamber 3. The pyrolysis gas generated by the cracking of the material 5 in the pyrolysis chamber 2 flows out of the pyrolysis chamber 2 along the pyrolysis gas conveying pipe 6 under the action of pressure difference. It is mixed with the air flowing in through the air inlet 14 in the pyrolysis gas conveying pipe 6 and then enters the combustion chamber 3 together. The pyrolysis gas is used as fuel to burn in the combustion chamber 3. The heat released by the combustion sustains the pyrolysis of the material 5 in the pyrolysis chamber 2. The pyrolysis gas generated by the pyrolysis enters the combustion chamber 3 to sustain the combustion and heat release in the combustion chamber 3. The system enters the self-sustaining stable operation stage. During the self-sustaining stable operation phase, materials are continuously fed into the pyrolysis chamber 2 according to step S1 to ensure a stable self-sustaining process. Throughout the process, no air supply is required in the pyrolysis chamber 2, and the material 5 undergoes pyrolysis under anaerobic conditions, thus achieving self-sustaining anaerobic pyrolysis of the material. The flue gas generated during the incineration process in the incineration chamber 3 is discharged from the flue gas outlet 15 and is discharged into the atmosphere after passing through dust removal, cooling, filtration, acid gas absorption, demisting and filtration in sequence.

[0039] S4. Shutdown Stop feeding materials into pyrolysis chamber 2, turn on the ignition system of the incineration chamber, and supply oil to the incineration chamber 3 again. The heat released by the diesel combustion maintains the pyrolysis of the residual materials in pyrolysis chamber 2. After 30 minutes of continuous oil supply and combustion, all materials 5 in pyrolysis chamber 2 are pyrolyzed. Stop the oil supply and wait for the system to cool down.

[0040] S5. Ash Removal Turn on the screw conveyor 7 inside the pyrolysis chamber 2 to transport the pyrolysis ash formed after the material 5 is pyrolyzed to the ash discharge port 8. Open the ash discharge port 8 to allow the pyrolysis ash to fall into the ash bucket 9, which is fixedly connected to the ash discharge port 8. After closing the ash discharge port 8, remove the ash bucket 9. The pyrolysis volume reduction treatment of polyethylene solid waste is completed.

[0041] In summary, this invention, through innovations in device structure, principle, and process, provides a self-sustaining anaerobic pyrolysis volume reduction treatment device and method for solid waste, especially plastic waste, enabling self-sustaining anaerobic pyrolysis. Compared to existing anoxic pyrolysis-incineration technologies, in this invention, the heat required for material pyrolysis comes entirely from the heat released by the combustion of pyrolysis gas in the incineration chamber. The heat released by the combustion of pyrolysis gas indirectly heats the material through the partition between the pyrolysis chamber and the incineration chamber, maintaining the pyrolysis of the material in the pyrolysis chamber. Furthermore, the pyrolysis gas produced by the anaerobic pyrolysis of the material in the pyrolysis chamber can be used as fuel to maintain the heat release from combustion in the incineration chamber, truly achieving stable operation of self-sustaining anaerobic pyrolysis without the need to introduce air into the pyrolysis chamber during the pyrolysis process. In contrast, existing anoxic pyrolysis-incineration technologies rely entirely on the heat released from the combustion of the bottom char layer material for material pyrolysis, thus requiring a continuous supply of air to the pyrolysis furnace. This invention overcomes the inherent defects of existing technologies and proposes a brand-new solution for solid waste treatment, especially for the treatment of low-level radioactive combustible solid waste such as plastics generated by nuclear power plants and other nuclear-related entities.

[0042] The materials and equipment used in this invention are all commercially available and can be purchased from retail sources. The above description is merely a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A self-sustaining anaerobic pyrolysis volume reduction treatment device for waste, characterized in that, The device includes an upper chamber and a lower chamber, which are completely separated by a high-temperature and corrosion-resistant composite material partition. The upper chamber is a pyrolysis chamber, in which the material is heated to the pyrolysis temperature and begins to decompose, producing pyrolysis gas. The lower chamber is an incineration chamber, in which the heat released from combustion heats the material in the pyrolysis chamber through the partition. The pyrolysis chamber and the incineration chamber are connected by a pyrolysis gas delivery pipe, through which the pyrolysis gas generated in the pyrolysis chamber enters the incineration chamber. The incineration chamber is equipped with a flue gas outlet for the outflow of flue gas generated during the incineration process; The incineration chamber is equipped with a fuel inlet and an air inlet for supplying fuel and air into the incineration chamber, respectively. The device is equipped with an induced draft fan at the end. Under the action of the induced draft fan, a negative pressure condition is formed in the combustion chamber, and the pyrolysis gas in the pyrolysis chamber flows out of the pyrolysis chamber along the pyrolysis gas conveying pipe under the action of pressure difference.

2. The self-sustaining anaerobic pyrolysis volume reduction treatment device for waste according to claim 1, characterized in that, The pyrolysis chamber is equipped with a screw conveyor mechanism to transport the pyrolysis ash formed after the material is pyrolyzed to the ash discharge port.

3. The self-sustaining anaerobic pyrolysis volume reduction treatment device for waste according to claim 2, characterized in that, The pyrolysis chamber and the spiral conveyor mechanism are both made of high-temperature and corrosion-resistant steel and are equipped with cooling water jackets.

4. The self-sustaining anaerobic pyrolysis volume reduction treatment device for waste according to claim 1, characterized in that, The incineration chamber is made of high-temperature and corrosion-resistant steel, and the inner walls of the incineration chamber are lined with refractory bricks.

5. The self-sustaining anaerobic pyrolysis volume reduction treatment device for waste according to claim 1, characterized in that, The pyrolysis chamber is provided with a feed inlet above it. An upper insert plate and a lower insert plate are provided from top to bottom on the feed pipe between the feed inlet and the pyrolysis chamber to ensure that the pyrolysis chamber is always sealed during feeding.

6. The self-sustaining anaerobic pyrolysis volume reduction treatment device for waste according to claim 1, characterized in that, A spiral feeding mechanism or conveyor belt is provided between the feed inlet and the upper insert plate to transport materials to the top of the upper insert plate.

7. A self-sustaining anaerobic pyrolysis volume reduction treatment method for waste, characterized in that, The method uses the self-sustaining anaerobic pyrolysis volume reduction device for waste treatment according to any one of claims 1-6 to perform pyrolysis volume reduction treatment, and the method includes the following steps: S1. Feeding Add materials to the pyrolysis chamber; S2. Oven Air and fuel are continuously supplied to the combustion chamber and ignited. The heat released by the combustion of fuel preheats the combustion chamber. Heat is transferred to the pyrolysis chamber through the partition between the combustion chamber and the pyrolysis chamber to heat the materials in the pyrolysis chamber. S3. Stable operation When the temperature inside the pyrolysis chamber rises to the pyrolysis temperature, the fuel supply to the combustion chamber is gradually reduced; once the temperature inside the pyrolysis chamber stabilizes at the pyrolysis temperature, the fuel supply to the combustion chamber is stopped; the pyrolysis gas generated by the pyrolysis of the material inside the pyrolysis chamber enters the combustion chamber through the pyrolysis gas conveying pipeline, and the pyrolysis gas is burned as fuel in the combustion chamber to release heat and maintain the pyrolysis of the material inside the pyrolysis chamber; during this period, the material is continuously fed into the pyrolysis chamber to ensure the stable operation of the self-sustaining pyrolysis system; S4. Shutdown Stop feeding materials into the pyrolysis chamber and supply fuel to the combustion chamber again. The heat released by the fuel combustion sustains the pyrolysis of the remaining materials in the pyrolysis chamber. After all the materials in the pyrolysis chamber have been pyrolyzed, stop supplying fuel to complete the pyrolysis volume reduction process.

8. The self-sustaining anaerobic pyrolysis volume reduction treatment method for waste according to claim 7, characterized in that, The pyrolysis temperature is 400~700℃.

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