Pyrolysis processing system and method for waste lithium battery materials

Abstract

The application discloses a pyrolysis treatment system and method for waste lithium battery materials, which comprises a pyrolysis reactor, a pyrolysis rotary kiln and a tail gas treatment unit. The material output end of the pyrolysis reactor is connected with the feeding port of the pyrolysis rotary kiln, and the gas outlet of the pyrolysis reactor and the gas outlet of the pyrolysis rotary kiln are both connected with the tail gas treatment unit. The upstream material enters the pyrolysis reactor for pyrolysis, and air is used as the reaction medium. The gas generated after pyrolysis enters the tail gas treatment unit for absorption, and the upstream material after pyrolysis enters the pyrolysis rotary kiln for high-temperature pyrolysis. The temperature in the pyrolysis rotary kiln is higher than that in the pyrolysis reactor, and the pyrolysis rotary kiln adopts a nitrogen atmosphere. The gas generated after high-temperature pyrolysis enters the tail gas treatment unit for absorption. The pyrolysis reactor, the pyrolysis rotary kiln and the alkali liquor absorption tank and other devices are arranged, so that the problems of insufficient pyrolysis, low energy utilization rate, complex tail gas composition and difficult treatment in the prior art are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste lithium battery recycling, in particular to a pyrolysis treatment system and method for waste lithium battery materials. BACKGROUND

[0002] With the rapid development of the electric vehicle market, the number of retired power lithium batteries is showing a sharp growth trend. Waste lithium batteries contain rich lithium, copper, cobalt and other metal resources, and their content is much higher than that of corresponding metals in natural ores, which has a very high recycling value. At present, waste lithium battery material recycling mainly adopts pyrometallurgy and hydrometallurgy methods, and pretreatment is an essential link for pyrometallurgy and hydrometallurgy. The black powder enriched in positive and negative materials can be obtained, mainly including discharging, disassembling, crushing, heat treatment, sorting and other processes. Among them, heat treatment is the key step to effectively separate electrode materials from electrolyte, separator, binder and current collector, and has a crucial influence on the smooth progress of the subsequent recovery process and the quality of the recovered products.

[0003] The heat treatment method in the prior art is commonly high-temperature vacuum pyrolysis. For example, patent application No. CN202021849209.2 discloses a battery pyrolysis equipment, which specifically uses a rotary kiln to perform high-temperature pyrolysis on waste batteries in a nitrogen atmosphere. In this process, the nitrogen atmosphere is relatively stable, but the pyrolysis process is not sufficient. Insufficient pyrolysis will cause the electrode materials and other components to not be completely separated, thereby affecting the quality of the black powder in the subsequent process and reducing the efficiency and economic benefits of the entire recovery process. For another example, patent application No. CN202410521869.4 discloses a waste lithium battery pyrolysis system and method, which specifically improves the combustion degree of waste lithium battery materials by setting a primary rotary kiln, a cooling kiln and a secondary rotary kiln. However, due to the increase in the number of equipment and the complexity of the process flow, the system energy consumption is greatly increased, and the energy utilization rate is low. For another example, patent application No. CN202311351012.4 discloses a retired lithium battery pyrolysis device, which includes two pyrolysis zones in the pyrolysis chamber, and at least one pyrolysis unit is arranged in each pyrolysis zone. The local temperature in the furnace body can be accurately controlled, and the pyrolysis efficiency of the pyrolysis device is effectively improved. However, due to the temperature gradient of the device and the high-temperature zone being arranged below the low-temperature zone, the tail gas generated during pyrolysis is easily condensed in the equipment, generating pyrolysis oil tightly adhered to the inner wall of the equipment, which affects the temperature control accuracy and reduces the pyrolysis efficiency and the quality of the pyrolysis products.

[0004] In addition, when the existing high-temperature vacuum pyrolysis method is used to treat waste lithium battery materials, the tail gas components generated are extremely complex, including polycyclic aromatic hydrocarbon organic gas, ester organic gas, fluorine-containing compounds, dioxin and other harmful substances. The treatment of these complex tail gas is extremely difficult, and the traditional tail gas treatment method often fails to achieve the ideal purification effect. If it is directly discharged without effective treatment, it will cause serious pollution to the environment, threaten the ecological balance, and also harm the health of the operating personnel, and cause a series of environmental and social problems. SUMMARY

[0005] In view of the problems in the prior art, the present application provides a pyrolysis treatment system and method for waste lithium battery materials, which solves the problems of insufficient pyrolysis, low energy utilization rate, complex tail gas components and difficult treatment in the prior art by setting a pyrolysis reactor, a pyrolysis rotary kiln and an alkali absorption tank and other devices.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a pyrolysis treatment system for waste lithium battery materials, comprising: a pyrolysis reactor, a pyrolysis rotary kiln and a tail gas treatment unit, the material output end of the pyrolysis reactor is connected with the feed inlet of the pyrolysis rotary kiln, and the gas outlet of the pyrolysis reactor and the gas outlet of the pyrolysis rotary kiln are both connected with the tail gas treatment unit.

[0008] The upstream material enters the pyrolysis reactor for pyrolysis, the pyrolysis reactor uses air as the reaction medium, the gas generated after pyrolysis enters the tail gas treatment unit for absorption, and the upstream material after pyrolysis enters the pyrolysis rotary kiln for high-temperature pyrolysis, the temperature in the pyrolysis rotary kiln is higher than that in the pyrolysis reactor, the pyrolysis rotary kiln uses a nitrogen atmosphere, and the gas generated after high-temperature pyrolysis enters the tail gas treatment unit for absorption.

[0009] As a further technical solution, the tail gas treatment unit comprises a spray tower and an alkali absorption tank; the gas generated after pyrolysis is carbon dioxide and water, which enters the spray tower with air, is condensed into carbonic acid first, and then enters the alkali absorption tank for treatment; the gas generated after high-temperature pyrolysis is a fluorine-containing compound, which enters the alkali absorption tank with nitrogen for treatment.

[0010] As a further technical solution, the temperature in the pyrolysis reactor is set to 200-300 DEG C, and the temperature in the pyrolysis rotary kiln is set to 550-600 DEG C.

[0011] As a further technical solution, the inside of the pyrolysis reactor is provided with a double-shaft stirring structure, the double-shaft stirring structure comprises two stirring shafts, a plurality of stirring units are arranged on each stirring shaft, and the stirring units on the two stirring shafts are staggered; the stirring unit comprises a material belt structure and a scraper; both sides of the material belt structure are provided with material belt hooks for scooping up materials.

[0012] As a further technical solution, the pyrolysis rotary kiln comprises a drum, the inside wall of the drum is provided with a plurality of material scooping plates, and the rotating shaft of the drum is provided with a spiral conveying structure.

[0013] As a further technical solution, it further comprises an air source, a steam source and a nitrogen source; the air source is connected with the pyrolysis reactor, the steam source is connected with the pyrolysis reactor and the pyrolysis rotary kiln respectively, and the nitrogen source is connected with the pyrolysis rotary kiln; wherein a steam heater is arranged between the nitrogen source and the pyrolysis rotary kiln, and the steam heater is used for heating the nitrogen source.

[0014] As a further technical solution, the pyrolysis reactor is connected with a cyclone dust collector, specifically: the air inlet end of the cyclone dust collector is connected with the air outlet end of the pyrolysis reactor, a secondary discharge port is arranged on the cyclone dust collector, the secondary discharge port is connected with the inside of the pyrolysis reactor, and the gas inlet of the cyclone dust collector is connected with a first fan.

[0015] As a further technical solution, one end of the first fan is connected with the gas inlet of the cyclone dust collector, and the other end of the first fan is connected with a spray tower, wherein the spray tower is filled with condensed water, and the outlet of the spray tower is connected with the alkali liquor absorption tank.

[0016] As a further technical solution, the air outlet of the pyrolysis rotary kiln is connected with a dust collector, and the dust collector is connected with the alkali liquor absorption tank through a second fan.

[0017] In a second aspect, the present application provides a pyrolysis treatment method for waste lithium battery materials, based on the pyrolysis treatment system for waste lithium battery materials in any one of the first aspect, comprising: upstream materials enter the inside of the pyrolysis reactor through the material input end, the temperature in the pyrolysis reactor is set to 200-300℃, and the inside of the pyrolysis reactor is an air atmosphere, the upstream materials are decomposed in the inside of the pyrolysis reactor, and air enters the cyclone dust collector from the air outlet of the pyrolysis reactor, the materials carried out by the air are collected in the cyclone dust collector, and after collection, they are returned to the inside of the pyrolysis reactor again through the secondary discharge port; the gas after dust removal of the cyclone dust collector passes through the first fan into the spray tower, and after condensation in the spray tower, it enters the alkali liquor absorption tank for absorption;

[0018] The upstream material after pyrolysis in the pyrolysis reactor enters a roller inside the pyrolysis rotary kiln, wherein the temperature inside the pyrolysis rotary kiln is set to 550-600 DEG C, and the inside of the pyrolysis rotary kiln is a nitrogen atmosphere, the material is pyrolyzed in the roller, and is accompanied by nitrogen to pass through the gas outlet of the pyrolysis rotary kiln, then passes through a dust collector and a second fan in turn, and enters an alkali absorption tank for absorption.

[0019] The one or more technical solutions of the present application have the following beneficial effects:

[0020] (1) Firstly, in the present application, the pyrolysis reactor is connected with an air source, and an air atmosphere is adopted. Compared with the traditional inert atmosphere, the pyrolysis is more complete and more sufficient. Secondly, the internal structures of the pyrolysis reactor and the pyrolysis rotary kiln are optimized. A double-shaft stirring structure is arranged in the pyrolysis reactor, which includes a material carrying structure and a scraper. A material lifting plate and a screw conveying structure are arranged in the pyrolysis rotary kiln. Through the synergistic effect of the internal structures of the pyrolysis reaction device and the pyrolysis rotary kiln, the degree of pyrolysis is significantly improved, the pyrolysis is more sufficient, the impurity content of the pyrolysis product is greatly reduced, the quality of the raw material for the subsequent recovery process is improved, and the metal recovery rate and the product quality of the entire recovery process are improved.

[0021] (2) The pyrolysis treatment system of the present application mainly includes a pyrolysis reactor and a pyrolysis rotary kiln. Compared with the traditional vacuum pyrolysis method, this reaction path avoids the problem of generating pyrolysis oil from alkane compounds in a vacuum high-temperature environment. The reduction of pyrolysis oil not only reduces the content of organic pollutants in the tail gas, but also makes the composition of the tail gas relatively simple. The tail gas can be absorbed and treated by the alkali absorption tank, which simplifies the tail gas treatment process, makes it easier to handle, greatly reduces the difficulty of tail gas treatment, and improves the efficiency and effect of tail gas treatment.

[0022] (3) The pyrolysis treatment system of the present application mainly includes a pyrolysis reactor and a pyrolysis rotary kiln. The inside of the pyrolysis reactor is an air atmosphere, and the inside of the pyrolysis rotary kiln is a nitrogen atmosphere. Compared with the traditional vacuum pyrolysis method, the amount of nitrogen used is greatly reduced, and the temperature segments set in the pyrolysis reactor and the pyrolysis rotary kiln are different. While ensuring sufficient pyrolysis, the energy utilization rate is also greatly improved, and the energy utilization rate is high. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings accompanying the specification of the present application serve to provide a further understanding of the present application, and the schematic embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0024] Figure 1 It is a structural schematic diagram of the pyrolysis treatment system of waste lithium battery materials of the present application;

[0025] Figure 2 It is a schematic diagram of the double-shaft stirring structure inside the pyrolysis reactor in the present application;

[0026] The components include: 1. Pyrolysis reactor; 1-1. Twin-shaft stirring structure; 1-1-1. Material conveying structure; 1-1-2. Scraper; 1-1-3. Material hook; 2. Pyrolysis rotary kiln; 2-1. Material lifting plate; 2-2. Screw conveyor structure; 3. Cyclone dust collector; 4. First fan; 5. Spray tower; 6. Alkali absorption tank; 7. Second fan; 8. Dust collector; 9. Steam heater; 10. Air source; 11. Steam source; 12. Nitrogen source; 13. Discharge port; 14. Condensate; 15. Material input end. Detailed Implementation

[0027] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] Example 1

[0029] This invention provides a pyrolysis treatment system for waste lithium battery materials, such as... Figure 1 As shown, the pyrolysis treatment system includes a pyrolysis reactor 1, a pyrolysis rotary kiln 2, an alkaline absorption tank 6, an air source 10, a steam source 11, and a nitrogen source 12. The material output end of the pyrolysis reactor 1 is connected to the feed inlet of the pyrolysis rotary kiln 2, and both the gas outlet of the pyrolysis reactor and the gas outlet of the pyrolysis rotary kiln are connected to the alkaline absorption tank 6. In this embodiment, the temperature inside the pyrolysis rotary kiln is higher than the temperature inside the pyrolysis reactor. Specifically, the temperature inside the pyrolysis reactor is set to 200℃-300℃ to facilitate the volatilization and decomposition of the electrolyte (mainly carbonate compounds) in the waste lithium battery materials into gaseous alkane compounds. The temperature inside the pyrolysis rotary kiln is set to 550℃-600℃ to facilitate the decomposition of the binder in the waste lithium battery materials. Other temperature ranges would lead to insufficient decomposition of the binder, affecting the pyrolysis treatment efficiency of the waste lithium battery materials.

[0030] Specifically: The pyrolysis reactor 1 is equipped with a biaxial stirring structure 1-1, such as... Figure 2As shown, the dual-shaft stirring structure includes two stirring shafts, each with several stirring units arranged in a staggered pattern. Each stirring unit includes a material-carrying structure 1-1-1 and a scraper 1-1-2. The material-carrying structure 1 scoops up the material, increasing the contact area between the material and the dual-shaft stirring structure. The scraper 2 removes material from the inner wall of the pyrolysis reactor and the stirring shafts. The rotation of the stirring shafts moves the material forward and provides shear force, breaking up clumps and ensuring complete pyrolysis in the subsequent rotary kiln. In this embodiment, material-carrying hooks 1-1-3 are provided on both sides of the material-carrying structure for scooping up the material. In this embodiment, a cyclone dust collector 3 is connected to the pyrolysis reactor. Specifically, the inlet of the cyclone dust collector is connected to the outlet of the pyrolysis reactor. The cyclone dust collector is provided with a secondary discharge port, which is connected to the interior of the pyrolysis reactor. The outlet of the cyclone dust collector is connected to a first fan 4. One end of the first fan is connected to the outlet of the cyclone dust collector, and the other end of the first fan is connected to a spray tower 5. The spray tower contains condensate 14, and the outlet of the spray tower is connected to an alkaline absorption tank 6. In this embodiment, the tail gas composition is relatively simple, and subsequent absorption and treatment by the spray tower and the alkaline absorption tank can simplify the tail gas treatment process, greatly reduce the difficulty of tail gas treatment, and improve the efficiency and effect of tail gas treatment.

[0031] In this embodiment, as Figure 1 As shown, the air source 10 is connected to the pyrolysis reactor 1, so that the atmosphere inside the pyrolysis reactor is air, ensuring that air is used as the reaction medium in the pyrolysis reaction device. On the one hand, compared with the traditional inert atmosphere, the pyrolysis in this embodiment is more complete and more thorough. On the other hand, it reduces the dependence on inert gases (such as nitrogen), thereby reducing the amount of nitrogen used.

[0032] Steam source 11 is connected to pyrolysis reactor 1 and pyrolysis rotary kiln 2 respectively. Specifically, steam is introduced into the rotating shaft of pyrolysis reactor and the inner wall of pyrolysis reaction device to exchange heat with materials in an indirect heating manner; steam is introduced into the inner wall of pyrolysis rotary kiln to provide heat to materials.

[0033] The nitrogen source is connected to the pyrolysis rotary kiln, specifically: such as Figure 1 As shown, a steam heater 9 is installed between the nitrogen source 12 and the pyrolysis rotary kiln. One end of the steam heater is connected to the nitrogen source, and the other end of the steam heater is connected to the pyrolysis rotary kiln. The steam heater is used to heat the nitrogen source.

[0034] In this embodiment, as Figure 1As shown, the pyrolysis rotary kiln includes a drum. Several lifting plate structures are installed on the inner wall of the drum, and a spiral conveying structure is installed on the rotating shaft of the drum. Specifically, as the drum rotates, the lifting plate structures on the inner wall of the drum can lift the material. The spiral conveying structure inside the drum drives the material to move. While conveying the material, it also provides a certain shearing force to the material that falls after being lifted by the lifting plate structures, breaking up the clumps in the material and ensuring the uniformity of pyrolysis.

[0035] In this embodiment, a dust collector 8 is connected to the outlet of the pyrolysis rotary kiln, and the dust collector is connected to the alkaline absorption tank 6 via a second fan 7. Furthermore, the pyrolysis rotary kiln utilizes a rational structural design (such as a lifting plate structure and a spiral conveyor structure to improve heat exchange efficiency) to make the pyrolysis process more efficient, further reducing energy consumption.

[0036] Meanwhile, due to the relatively simple composition of the exhaust gas, the treatment difficulty is reduced, and the energy consumption in the exhaust gas treatment process is also reduced accordingly. Therefore, the energy utilization rate of the entire system is greatly improved, meeting the requirements of energy conservation, emission reduction, and sustainable development. In addition, pollutants such as fluorine-containing compounds generated during pyrolysis can be effectively treated through an alkaline absorption tank, further reducing the potential harm to the environment and making the entire pyrolysis treatment process of waste lithium battery materials more environmentally friendly and safe.

[0037] Example 2

[0038] This embodiment provides a pyrolysis treatment method for waste lithium battery materials, based on the pyrolysis treatment system for waste lithium battery materials provided in Embodiment 1. The pyrolysis treatment method includes two parts: a pyrolysis process and a high-temperature pyrolysis process. The specific method of the pyrolysis process is as follows: upstream materials (waste lithium batteries after discharge, dismantling, and crushing) enter the interior of the pyrolysis reactor through the material input end. The internal temperature of the pyrolysis reactor is set to 200℃-300℃. The electrolyte (mainly carbonate compounds) in the waste lithium battery materials volatilizes and decomposes into gaseous alkane compounds at this temperature. Since the interior of the pyrolysis reactor is an air atmosphere, the gaseous alkane compounds can fully contact oxygen and undergo an oxidation reaction, ultimately producing carbon dioxide and water. Compared with the traditional vacuum pyrolysis method, this reaction path avoids the problem of alkane compounds generating pyrolysis oil under vacuum and high-temperature conditions. The reduction of pyrolysis oil not only reduces the content of organic pollutants in the exhaust gas, making the exhaust gas composition relatively simple, but also greatly reduces the difficulty of exhaust gas treatment.

[0039] The twin-shaft stirring structure in the pyrolysis reactor drives the material movement. The material-carrying structure on the twin-shaft stirring structure can lift the material, increasing the contact area between the material and the stirring unit. The scraper on the twin-shaft stirring structure can remove the material on the inner wall of the pyrolysis reactor. The rotation of the stirring shaft of the twin-shaft stirring structure drives the material movement and provides shear force to break up the clumps in the material. The material decomposes inside the pyrolysis reactor and enters the cyclone dust collector from the gas outlet of the pyrolysis reactor along with the air. The material carried out by the air is collected in the cyclone dust collector and then returned to the inside of the pyrolysis reactor through the secondary discharge port. The gas after dust removal by the cyclone dust collector enters the spray tower through the air outlet via the first fan. After condensation in the spray tower, it enters the alkaline absorption tank for absorption. In other words, the subsequent tail gas treatment process only requires condensing carbon dioxide and water in the spray tower to generate carbonic acid, and then treating it through the alkaline absorption tank. This greatly simplifies the tail gas treatment process and improves the efficiency and effect of tail gas treatment.

[0040] The specific method of the high-temperature pyrolysis process is as follows: the waste lithium batteries processed by the pyrolysis reactor enter the drum inside the pyrolysis rotary kiln through the feed port of the pyrolysis rotary kiln from the material output end of the pyrolysis reactor. The internal temperature of the pyrolysis rotary kiln is set at 550℃-600℃, and the interior of the pyrolysis rotary kiln is in a nitrogen atmosphere. The screw conveyor structure drives the material to move in the drum. The material is pyrolyzed at high temperature in the drum. The high-temperature pyrolysis process removes the binder in the material at 550℃-600℃. The main component of the binder is polyvinylidene fluoride. After high-temperature pyrolysis, fluorine-containing compounds are generated. The fluorine-containing compounds, along with nitrogen gas, pass through the gas outlet of the pyrolysis rotary kiln and enter the alkaline absorption tank after passing through the dust collector and the second fan. The fluorine-containing compounds react with the alkaline solution to form a precipitate for removal.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for pyrolysis treatment of waste lithium battery materials, characterized in that, include: After being discharged, disassembled, and crushed, the waste lithium batteries enter the pyrolysis reactor through the material input end. The internal temperature of the pyrolysis reactor is set at 200℃-300℃. At this temperature, the electrolyte in the waste lithium battery material volatilizes and decomposes into gaseous alkane compounds. Since the inside of the pyrolysis reactor is an air atmosphere, the gaseous alkane compounds can fully contact oxygen and undergo an oxidation reaction, ultimately producing carbon dioxide and water. The carbon dioxide and water produced after pyrolysis are then treated sequentially through a cyclone dust collector, a spray tower, and an alkaline absorption tank. The pyrolyzed material then enters the pyrolysis rotary kiln for high-temperature pyrolysis. The internal temperature of the pyrolysis rotary kiln is set at 500℃-600℃, and it is in a nitrogen atmosphere. The fluorine-containing compounds produced after high-temperature pyrolysis are then treated in the alkaline absorption tank. The material carried out by the air is collected in the cyclone dust collector, and after collection, it returns to the interior of the pyrolysis reactor through the secondary discharge port, and enters the pyrolysis rotary kiln together with the pyrolysis material; and the fluorine-containing compounds generated after high-temperature pyrolysis are discharged from the gas outlet of the pyrolysis rotary kiln, pass through the dust collector and the second fan in sequence, and then enter the alkaline absorption tank for absorption.

2. The pyrolysis treatment method for waste lithium battery materials as described in claim 1, characterized in that, The gases produced after pyrolysis in the pyrolysis reactor are carbon dioxide and water, which enter the spray tower with the air, first condense into carbonic acid, and then enter the alkaline absorption tank for treatment; the gases produced after high-temperature pyrolysis in the pyrolysis rotary kiln are fluorine-containing compounds, which enter the alkaline absorption tank with nitrogen for treatment.

3. The pyrolysis treatment method for waste lithium battery materials as described in claim 1, characterized in that, The pyrolysis reactor is equipped with a dual-shaft stirring structure, which includes two stirring shafts. Each stirring shaft has several stirring units, and the stirring units on the two stirring shafts are arranged alternately. Each stirring unit includes a material carrying structure and a scraper. The material carrying structure has material carrying hooks on both sides, which are used to pick up the material.

4. The pyrolysis treatment method for waste lithium battery materials as described in claim 1, characterized in that, The pyrolysis rotary kiln includes a drum, on the inner wall of which are provided several lifting plates, and on the rotating shaft of the drum are provided a spiral conveying structure.

5. The pyrolysis treatment method for waste lithium battery materials as described in claim 1, characterized in that, It also includes an air source, a steam source, and a nitrogen source; the air source is connected to the pyrolysis reactor, the steam source is connected to both the pyrolysis reactor and the pyrolysis rotary kiln, and the nitrogen source is connected to the pyrolysis rotary kiln; wherein a steam heater is provided between the nitrogen source and the pyrolysis rotary kiln, and the steam heater is used to heat the nitrogen source.

6. The pyrolysis treatment method for waste lithium battery materials as described in claim 1, characterized in that, A cyclone dust collector is connected to the pyrolysis reactor. The inlet of the cyclone dust collector is connected to the outlet of the pyrolysis reactor. The cyclone dust collector has a secondary discharge port connected to the interior of the pyrolysis reactor. A first fan is connected to the air outlet of the cyclone dust collector. One end of the first fan is connected to the air outlet of the cyclone dust collector, and the other end of the first fan is connected to a spray tower, in which condensate is circulated. The outlet of the spray tower is connected to the alkali absorption tank. A dust collector is connected to the outlet of the pyrolysis rotary kiln, and the dust collector is connected to the alkali absorption tank via a second fan.

Images