A device for recycling waste heat of two combustion chambers of a pyrolysis furnace and a use method thereof

Abstract

This invention discloses a waste heat recovery device and its usage method for a secondary combustion chamber in a pyrolysis furnace, relating to the field of pyrolysis furnace technology. The device includes a pyrolysis furnace body, a fan, a secondary combustion chamber body, a thermometer, an explosion relief valve, an ash removal door, a furnace body, a filter mechanism, a blower, an air guide hood, a waste gas pipe, a regenerative diversion pipe, a low-NOx burner, an oxygen supply mechanism, a conveying pipe, air vents, finned tubes, and an air inlet pipe. The top cavity of the pyrolysis furnace body is connected to the bottom air inlet cavity of the secondary combustion chamber body. A fan is installed in the internal cavity of the pyrolysis furnace body, and an air inlet pipe is installed on the side wall of the pyrolysis furnace body, with one end of the air inlet pipe connected to the internal cavity of the pyrolysis furnace body. This invention can effectively decompose harmful components in flue gas, ensuring that flue gas emissions meet standards. Simultaneously, it efficiently recovers waste heat from the flue gas to achieve cascade utilization of thermal energy, reducing system operating energy consumption and improving equipment safety and environmental protection. It is suitable for the harmless pyrolysis disposal and resource recovery of hazardous waste such as decommissioned photovoltaic panels.

Description

Technical Field

[0001] This invention relates to the field of pyrolysis furnace technology, and in particular to a waste heat recovery device for a secondary combustion chamber of a pyrolysis furnace and a method of using the waste heat recovery device for a secondary combustion chamber of a pyrolysis furnace. Background Technology

[0002] Retired photovoltaic panels are mainly composed of tempered glass, crystalline silicon solar cells, aluminum frames, EVA film, and fluorinated backsheets. They contain not only recyclable valuable resources such as silicon, silver, and aluminum, but also toxic and hazardous components such as fluorinated polymers and heavy metals, classifying them as hazardous waste. Direct landfilling or incineration without proper disposal will cause severe soil, water, and air pollution, while also wasting a large amount of valuable resources. Therefore, the harmless disposal and resource recycling of retired photovoltaic panels has become a critical issue urgently needing to be addressed for the sustainable development of the photovoltaic industry. In the disposal of decommissioned photovoltaic panels, anoxic pyrolysis is often used to reduce material volume and recover resources. During operation, existing pyrolysis furnaces generate large amounts of pyrolysis gas containing tar, VOCs, dioxin precursors, CO, and other combustible and harmful components. This pyrolysis gas needs to be sent to a secondary combustion chamber for high-temperature combustion and decomposition to meet emission standards.

[0003] In existing technologies, the high-temperature flue gas generated after combustion in the secondary combustion chamber is usually directly discharged after simple cooling and dust removal. The large amount of excess heat carried in the flue gas is not effectively utilized, resulting in serious energy waste. At the same time, a large amount of fuel needs to be consumed additionally for furnace preheating during the start-up phase of the pyrolysis furnace, resulting in high overall operating energy consumption and low energy utilization rate, making it impossible to achieve the cascade utilization of thermal energy.

[0004] In addition, existing combined pyrolysis and secondary combustion chamber devices mostly adopt a split layout, which is prone to safety risks such as positive pressure backfire and deflagration in the pyrolysis furnace. Furthermore, the pollutants in the flue gas are not fully decomposed and the amount of nitrogen oxides generated is high, which cannot meet the increasingly stringent environmental emission requirements. The system's operational stability and safety are insufficient. Therefore, there is an urgent need for a waste heat recovery device for the secondary combustion chamber of a pyrolysis furnace to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention discloses a waste heat recovery device and method for a secondary combustion chamber in a pyrolysis furnace. The device directly installs the secondary combustion chamber body on top of the pyrolysis furnace body. Combustible and harmful flue gas generated during pyrolysis, containing tar, VOCs, carbon monoxide, and dioxin precursors, can directly enter the secondary combustion chamber body. Under a high-temperature, oxygen-rich environment, the harmful components are fully oxidized and decomposed, effectively destroying toxic organic matter and significantly reducing the concentration of pollutants in the flue gas. Simultaneously, a filtration mechanism is used to intercept dust, heavy metals, and other components in the flue gas, ensuring that the flue gas meets emission standards, reducing equipment blockage caused by tar adhesion, and improving system operational stability. By coordinating the furnace body, finned tubes, and blower, the waste heat of the high-temperature flue gas discharged from the secondary combustion chamber is efficiently recovered. The heat exchanged gas flow is introduced into the external pyrolysis furnace through the conveying pipe for preheating. This fully utilizes the surplus heat generated by flue gas combustion, reduces fuel consumption during the preheating stage of the external pyrolysis furnace, and lowers the operating cost of the entire system. At the same time, it can quickly increase the furnace body temperature, shorten the pyrolysis furnace heating and start-up time, realize the cascade utilization of thermal energy, significantly improve the energy utilization rate of the entire pyrolysis system, and achieve remarkable energy-saving and environmental protection effects. By introducing nitrogen and air into the pyrolysis furnace body through the air inlet pipe, the oxygen concentration inside the furnace can be precisely controlled. Before pyrolysis, the air inside the furnace is replaced with nitrogen to prevent the pyrolysis gas from mixing with air to form an explosive mixture, thus preventing safety accidents such as deflagration and backfire. In conjunction with the explosion relief valve, temperature measuring instrument and low-NOx burner installed on the secondary combustion chamber, the furnace pressure and temperature can be controlled in real time, while effectively controlling the generation of nitrogen oxides, further improving the system's operational safety and environmental performance, and meeting strict atmospheric emission standards. In summary, the problems in the background technology are solved.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: The present invention provides a waste heat recovery device for a secondary combustion chamber of a pyrolysis furnace, comprising a pyrolysis furnace body, a fan, a secondary combustion chamber body, a thermometer, an explosion relief valve, an ash removal door, a furnace body, a filter mechanism, a blower, an air guide hood, a waste gas pipe, a heat recovery diversion pipe, a low-NOx burner, an oxygen supply mechanism, a conveying pipe, air holes, finned tubes, and an air inlet pipe. The top cavity of the pyrolysis furnace body is connected to the bottom air inlet cavity of the secondary combustion chamber body. A fan is installed in the internal cavity of the pyrolysis furnace body. An air inlet pipe is installed on the side wall of the pyrolysis furnace body. One end of the air inlet pipe is connected to the internal cavity of the pyrolysis furnace body, and the other end of the air inlet pipe extends to the outside of the pyrolysis furnace body. A low-NOx burner, an oxygen supply mechanism, a thermometer, an explosion relief valve, and an ash removal door are respectively installed on the side wall of the secondary combustion chamber body. The combustion end of the low-NOx burner extends into the internal cavity of the secondary combustion chamber body. The outlet end of the oxygen supply mechanism extends into the internal cavity of the secondary combustion chamber body. The detection end of the thermometer extends into the internal cavity of the secondary combustion chamber body. The air inlet end of the explosion relief valve is connected to the internal cavity of the secondary combustion chamber body. The ash removal door is sealed to the inspection port on the side wall of the secondary combustion chamber body. A regenerative diversion pipe is installed at the bottom of one side of the pyrolysis furnace body. One end of the regenerative diversion pipe is connected to the center of the bottom surface inside the pyrolysis furnace body, and the other end extends to the outside of the pyrolysis furnace body. A filter mechanism and a finned tube are sequentially arranged in the internal cavity of the furnace body. The air inlet of the filter mechanism is connected to the air outlet of the secondary combustion chamber body, and the air outlet of the filter mechanism is connected to the bottom air inlet of the finned tube. The tube wall of the finned tube is provided with multiple sets of air holes, and the top air outlet of the finned tube is connected to the air inlet of the air guide shroud. The air guide hood is fixed to the top of the furnace body and communicates with the interior of the furnace body. The air outlet of the air guide hood is connected to one end of the exhaust pipe, and the other end of the exhaust pipe extends to the outside of the furnace body. A blower is installed on the side wall of the furnace body. The air outlet of the blower extends to the internal cavity of the furnace body and faces the outer wall of the finned tube. A conveying pipe is installed on the side wall of the furnace body. One end of the conveying pipe is connected to the internal cavity of the furnace body, and the other end of the conveying pipe extends to the outside of the furnace body and communicates with the air inlet cavity of another pyrolysis furnace.

[0007] Furthermore, the fan is fixed to the top inner wall of the pyrolysis furnace body, and the air outlet direction of the fan is towards the bottom cavity of the pyrolysis furnace body; the air inlet pipe is provided on the lower side wall of the pyrolysis furnace body, and the air outlet end of the air inlet pipe is towards the center of the internal cavity of the pyrolysis furnace body.

[0008] Furthermore, the low-NOx burner and the oxygen supply mechanism are both located on the back of the secondary combustion chamber body, with the combustion end of the low-NOx burner and the outlet end of the oxygen supply mechanism at the same horizontal height; the temperature measuring instrument is located on the upper front of the secondary combustion chamber body, with the detection end of the temperature measuring instrument facing the inner cavity of the secondary combustion chamber body.

[0009] Furthermore, the explosion relief valve is located at the top of the secondary combustion chamber body, and the pressure relief direction of the explosion relief valve faces the outside and upward of the secondary combustion chamber body; the ash removal door is located on the lower side wall of the secondary combustion chamber body, and the bottom edge of the ash removal door is flush with the bottom surface of the internal cavity of the secondary combustion chamber body.

[0010] Furthermore, the filter mechanism is fixed to the lower cavity of the furnace body, and the outer edge of the filter mechanism is sealed and fitted to the inner wall of the furnace body; the finned tube is vertically arranged along the height direction of the furnace body, and the bottom air inlet end of the finned tube is sealed and connected to the top air outlet end of the filter mechanism.

[0011] Furthermore, the air vents are evenly distributed along the circumference and axial direction of the finned tube wall, and the two ends of the air vents are respectively connected to the internal cavity of the finned tube and the internal cavity of the furnace body; multiple sets of fins are provided on the outer wall of the finned tube, and the fins are arranged at equal intervals along the axial direction of the finned tube.

[0012] Furthermore, the air inlet opening of the air guide hood is larger than the air outlet opening, and the air inlet of the air guide hood covers the outside of the top air outlet of the finned tube; the air inlet of the exhaust pipe is sealed and connected to the air outlet of the air guide hood, and the exhaust pipe extends vertically to the outside of the furnace body.

[0013] Furthermore, the blower is located on the front side wall of the furnace body, with the blower's outlet facing the lower outer wall of the finned tube; the conveying pipe is located on the back of the furnace body, with the inlet of the conveying pipe communicating with the internal cavity of the furnace body.

[0014] A method for using a waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace includes the following steps: Step 1: Nitrogen gas is introduced into the pyrolysis furnace body through the air inlet pipe to replace the internal air. The fan inside the pyrolysis furnace body is started, and the pyrolysis furnace body pyrolyzes the internal materials. The flue gas generated by pyrolysis enters the secondary combustion chamber body. Step 2: The low-NOx burner on the side wall of the secondary combustion chamber is started, the oxygen supply mechanism replenishes oxygen into the secondary combustion chamber, the flue gas burns inside the secondary combustion chamber, the thermometer monitors the internal temperature of the secondary combustion chamber in real time, the explosion relief valve relieves overpressure in the secondary combustion chamber, and the ash cleaning door is used for shutdown and ash cleaning of the secondary combustion chamber. Step 3: The flue gas after combustion in the secondary combustion chamber is filtered by the filtration mechanism and then enters the finned tube. The blower blows air into the furnace body, and the air comes into contact with the outer wall of the finned tube for heat exchange. The heat-exchanged air is then transported to another pyrolysis furnace for preheating through the conveying pipe. Step 4: The flue gas inside the finned tube is guided by the air guide hood and then discharged through the exhaust pipe to the subsequent treatment process.

[0015] The present invention has the following advantages over the prior art: (1) This technical solution directly sets the secondary combustion chamber body on the top of the pyrolysis furnace body. The combustible and harmful flue gas containing tar, VOCs, carbon monoxide and dioxin precursors generated by pyrolysis can directly enter the secondary combustion chamber body. Under the high temperature and oxygen-rich environment, the harmful components are fully oxidized and decomposed, effectively destroying toxic organic matter and significantly reducing the concentration of pollutants in the flue gas. At the same time, the filter mechanism is used to intercept the dust, heavy metals and other components in the flue gas, ensuring that the flue gas meets the emission standards, reducing the equipment blockage problem caused by tar adhesion, and improving the stability of system operation. (2) This technical solution utilizes the combination of furnace body, finned tube and blower to efficiently recover the waste heat of high temperature flue gas discharged from the secondary combustion chamber. The heat exchanged hot gas flow is introduced into the external pyrolysis furnace through the conveying pipe for preheating. This can make full use of the surplus heat generated by flue gas combustion, reduce fuel consumption in the preheating stage of the external pyrolysis furnace, and reduce the operating cost of the whole system. At the same time, it can quickly increase the furnace body temperature, shorten the pyrolysis furnace heating and start-up time, realize the cascade utilization of heat energy, greatly improve the energy utilization rate of the whole pyrolysis system, and achieve significant energy saving and environmental protection effects. (3) This technical solution introduces nitrogen and air into the pyrolysis furnace body through the air inlet pipe, which can accurately control the oxygen concentration in the furnace. Before pyrolysis, nitrogen replaces the air in the furnace to avoid the pyrolysis gas and air mixing to form an explosive mixture, thus preventing safety accidents such as deflagration and backfire. With the explosion relief valve, thermometer and low nitrogen burner installed on the secondary combustion chamber body, the furnace pressure and temperature can be controlled in real time, and the generation of nitrogen oxides can be effectively controlled, further improving the system's operational safety and environmental performance, and meeting strict atmospheric emission standards. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention; Figure 2 This is a schematic diagram of the structure from another perspective of the present invention; Figure 3 This is a schematic diagram of the bottom view structure of the present invention; Figure 4 This is a schematic diagram of the internal structure of the pyrolysis furnace body of the present invention; Figure 5 This is a schematic diagram of the internal cross-sectional structure of the present invention; Figure 6 This is a schematic diagram of the internal cross-sectional structure of the furnace body of the present invention; Figure 7 This is a schematic diagram of the frontal planar structure of the present invention; Figure 8 This is a top-view planar structural diagram of the present invention.

[0018] In the diagram: 1. Pyrolysis furnace body; 2. Fan; 3. Secondary combustion chamber body; 4. Thermometer; 5. Explosion relief valve; 6. Ash removal door; 7. Furnace body; 8. Filter mechanism; 9. Blower; 10. Air guide hood; 11. Exhaust gas pipe; 12. Regenerator diversion pipe; 13. Low-NOx burner; 14. Oxygen supply mechanism; 15. Conveying pipe; 16. Air vent; 17. Finned tube; 18. Inlet pipe. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "surface", "side", "gap", "peripheral", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0021] Reference Figures 1-8 A waste heat recovery device for a secondary combustion chamber of a pyrolysis furnace includes a pyrolysis furnace body 1, a fan 2, a secondary combustion chamber body 3, a thermometer 4, an explosion relief valve 5, an ash cleaning door 6, a furnace body 7, a filter mechanism 8, a blower 9, an air guide hood 10, an exhaust pipe 11, a heat recovery diversion pipe 12, a low-NOx burner 13, an oxygen replenishment mechanism 14, a conveying pipe 15, an air hole 16, a finned tube 17, and an air inlet pipe 18. The top cavity of the pyrolysis furnace body 1 is connected to the bottom air inlet cavity of the secondary combustion chamber body 3. A fan 2 is installed in the internal cavity of the pyrolysis furnace body 1. An air inlet pipe 18 is installed on the side wall of the pyrolysis furnace body 1. One end of the air inlet pipe 18 is connected to the internal cavity of the pyrolysis furnace body 1, and the other end of the air inlet pipe 18 extends to the outside of the pyrolysis furnace body 1. A low-NOx burner 13, an oxygen supply mechanism 14, a thermometer 4, an explosion relief valve 5, and an ash removal door 6 are respectively installed on the side wall of the secondary combustion chamber body 3. The combustion end of the low-NOx burner 13 extends to the internal cavity of the secondary combustion chamber body 3. The outlet end of the oxygen supply mechanism 14 extends to the internal cavity of the secondary combustion chamber body 3. The detection end of the thermometer 4 extends to the internal cavity of the secondary combustion chamber body 3. The air inlet end of the explosion relief valve 5 is connected to the internal cavity of the secondary combustion chamber body 3. The ash removal door 6 is sealed to the inspection port on the side wall of the secondary combustion chamber body 3. A regenerating diversion pipe 12 is installed at the bottom of one side of the pyrolysis furnace body 1. One end of the regenerating diversion pipe 12 is connected to the center of the bottom surface inside the pyrolysis furnace body 1, and the other end of the regenerating diversion pipe 12 extends to the outside of the pyrolysis furnace body 1. A filter mechanism 8 and a finned tube 17 are sequentially installed in the internal cavity of the furnace body 7. The air inlet of the filter mechanism 8 is connected to the air outlet of the secondary combustion chamber body 3, and the air outlet of the filter mechanism 8 is connected to the bottom air inlet of the finned tube 17. Multiple sets of air holes 16 are provided on the tube wall of the finned tube 17, and the top air outlet of the finned tube 17 is connected to the air inlet of the air guide shroud 10. The air guide hood 10 is fixed to the top of the furnace body 7 and communicates with the interior of the furnace body 7. The air outlet of the air guide hood 10 is connected to one end of the exhaust pipe 11, and the other end of the exhaust pipe 11 extends to the outside of the furnace body 7. A blower 9 is provided on the side wall of the furnace body 7. The air outlet of the blower 9 extends to the internal cavity of the furnace body 7 and faces the outer wall of the finned tube 17. A conveying pipe 15 is provided on the side wall of the furnace body 7. One end of the conveying pipe 15 is connected to the internal cavity of the furnace body 7, and the other end of the conveying pipe 15 extends to the outside of the furnace body 7 and communicates with the air inlet cavity of another pyrolysis furnace. The fan 2 is fixed to the top inner wall of the pyrolysis furnace body 1, and the air outlet of the fan 2 is directed towards the bottom cavity of the pyrolysis furnace body 1; the air inlet pipe 18 is located on the lower side wall of the pyrolysis furnace body 1, and the air outlet of the air inlet pipe 18 is directed towards the center of the internal cavity of the pyrolysis furnace body 1; the low-NOx burner 13 and the oxygen supply mechanism 14 are both located on the back of the secondary combustion chamber body 3, and the combustion end of the low-NOx burner 13 and the air outlet of the oxygen supply mechanism 14 are at the same horizontal level; the thermometer 4 is located on the upper front of the secondary combustion chamber body 3, and the detection end of the thermometer 4 is directed towards the inner cavity of the secondary combustion chamber body 3. The explosion relief valve 5 is located on the top of the secondary combustion chamber body 3, and the pressure relief direction of the explosion relief valve 5 is towards the outside and above of the secondary combustion chamber body 3; the ash removal door 6 is located on the lower side wall of the secondary combustion chamber body 3, and the bottom edge of the ash removal door 6 is flush with the bottom surface of the internal cavity of the secondary combustion chamber body 3; the filter mechanism 8 is fixed to the lower cavity of the furnace body 7, and the outer edge of the filter mechanism 8 is sealed and fitted to the inner wall of the furnace body 7; the finned tube 17 is vertically arranged along the height direction of the furnace body 7, and the bottom air inlet end of the finned tube 17 is sealed and connected to the top air outlet end of the filter mechanism 8. The air vents 16 are evenly distributed along the circumference and axial direction of the finned tube 17. The two ends of the air vents 16 are connected to the internal cavity of the finned tube 17 and the internal cavity of the furnace body 7, respectively. Multiple sets of fins are provided on the outer wall of the finned tube 17. The fins are arranged at equal intervals along the axial direction of the finned tube 17. The air inlet opening size of the air guide shroud 10 is larger than the air outlet opening size. The air inlet of the air guide shroud 10 covers the outside of the top air outlet of the finned tube 17. The air inlet of the exhaust pipe 11 is sealed and connected to the air outlet of the air guide shroud 10. The exhaust pipe 11 extends vertically to the outside of the furnace body 7. Blower 9 is located on the front side wall of furnace body 7, with the air outlet of blower 9 facing the lower outer wall of finned tube 17; conveying pipe 15 is located on the back of furnace body 7, with the air inlet of conveying pipe 15 connected to the internal cavity of furnace body 7.

[0022] In the specific implementation process, nitrogen gas is first introduced into the pyrolysis furnace body 1 through the air inlet pipe 18 to replace the air in the furnace and create an inert oxygen-free environment inside the furnace. After the replacement is completed, the decommissioned photovoltaic panel material to be processed is sent into the pyrolysis furnace body 1. The heating system and fan 2 of the pyrolysis furnace body 1 are started. The fan 2 drives the airflow circulation in the furnace to maintain the furnace temperature at 500-600℃. The material completes pyrolysis in an oxygen-deficient environment. The pyrolysis flue gas containing tar, VOCs, dioxin precursors, CO and other combustible and harmful components produced by pyrolysis enters the secondary combustion chamber body 3 directly from the top of the pyrolysis furnace body 1. Subsequently, the low-NOx burner 13 and the oxygen supply mechanism 14 are started. The low-NOx burner 13 ignites the pyrolysis flue gas, and the oxygen supply mechanism 14 replenishes oxygen into the secondary combustion chamber 3, so that the temperature inside the secondary combustion chamber 3 is stably controlled at 1000℃. The flue gas stays in the high-temperature and oxygen-rich environment for more than 2 seconds to complete the full oxidation and decomposition of harmful components. The thermometer 4 monitors the flue gas temperature inside the secondary combustion chamber 3 in real time. When the temperature is lower than the set value, the system automatically adjusts the output power of the low-NOx burner 13 to ensure the decomposition effect of harmful components. When the pressure inside the secondary combustion chamber 3 rises instantaneously, the explosion relief valve 5 automatically opens to complete the pressure relief and ensure the safe operation of the equipment. After the equipment is shut down, the coke and dust deposited inside the secondary combustion chamber 3 can be cleaned through the ash cleaning door 6. After being treated by the secondary combustion chamber 3, the high-temperature flue gas flows through the filtration mechanism 8. Dust, heavy metals, and other solid particles carried in the flue gas are trapped by the filtration mechanism 8. The filtered clean high-temperature flue gas enters the interior of the finned tube 17. At the same time, the blower 9 starts and blows room-temperature air into the furnace body 7. The airflow flows from bottom to top along the outer wall of the finned tube 17, and completes efficient heat exchange with the high-temperature flue gas inside the finned tube 17. The heated airflow gathers in the cavity of the furnace body 7 and is transported to the interior of the external pyrolysis furnace through the conveying pipe 15, providing a preheating heat source for the start-up stage of the external pyrolysis furnace. After heat exchange, the flue gas enters the air guide hood 10 through the top of the finned tube 17. After being guided and gathered by the air guide hood 10, it is discharged through the exhaust pipe 11 to the subsequent flue gas treatment process, completing the entire pyrolysis flue gas purification and waste heat recovery process. Among them, the fan 2 is fixed to the top inner wall of the pyrolysis furnace body 1 and the air outlet direction is towards the bottom cavity. It can effectively drive the airflow in the furnace to form an up-and-down circulation, so that the temperature and oxygen content in the furnace are evenly distributed, and the uniformity and stability of the material pyrolysis are improved. The air inlet pipe 18 is set on the lower side wall of the pyrolysis furnace body 1 and the air outlet is facing the center of the cavity. It can effectively improve the diffusion efficiency of the nitrogen and air introduced into the furnace, realize the precise control of the oxygen concentration in the furnace, and at the same time avoid the fluctuation of the pyrolysis state caused by the airflow directly impacting the material. Among them, the combustion end and the gas outlet end of the low-NOx burner 13 and the oxygen supply mechanism 14 are at the same horizontal height, which can effectively mix the supplied oxygen with the combustible flue gas and the combustion flame, improve the completeness of flue gas combustion, and at the same time effectively reduce the formation of local high temperature zones and inhibit the generation of nitrogen oxides. The thermometer 4 is set on the upper front of the secondary combustion chamber body 3 with the detection end facing the inner cavity of the secondary combustion chamber body 3, which can effectively monitor the real-time temperature of the flue gas after combustion and decomposition, accurately judge the decomposition effect of harmful components in the flue gas, provide a reliable basis for adjusting the combustion power, and ensure that the flue gas treatment meets the standards. Among them, the explosion relief valve 5 is located at the top of the secondary combustion chamber body 3 and the pressure relief direction is facing outward and upward. It can quickly open to relieve pressure when the pressure in the furnace exceeds the limit, effectively avoiding the impact of the pressure relief airflow on the surrounding equipment and operators, and improving the safety protection performance of the equipment operation. The ash removal door 6 is located on the lower side wall of the secondary combustion chamber body 3 and the bottom edge is flush with the bottom surface of the inner cavity. It can effectively reduce the difficulty of cleaning the coke and dust deposited in the furnace, facilitate the comprehensive development of cleaning operations, avoid flue blockage, and ensure the long-term stable operation of the equipment. The filter mechanism 8 is fixed to the lower cavity of the furnace body 7 and its outer edge is sealed to the inner wall of the furnace body 7. This can effectively prevent high-temperature flue gas from flowing directly without filtration, ensuring the interception effect of particulate matter such as dust and heavy metals in the flue gas, improving the flue gas purification quality, and at the same time preventing particulate matter from entering the finned tube 17 and causing wear and blockage of the tube wall. The finned tube 17 is set vertically along the height of the furnace body 7 and its bottom is sealed to the air outlet of the filter mechanism 8. This can effectively ensure that all the filtered clean flue gas enters the interior of the finned tube 17 to complete heat exchange, improving the efficiency and stability of waste heat recovery. Among them, the air holes 16 are evenly distributed along the circumference and axial direction of the finned tube 17, which can effectively promote the heat exchange between the high temperature flue gas inside the finned tube 17 and the airflow outside the tube, improve the uniformity and sufficiency of heat exchange, and balance the pressure inside and outside the finned tube 17 to avoid equipment damage caused by excessive pressure inside the tube. The fins on the outer wall of the finned tube 17 are arranged at equal intervals along the axial direction, which can effectively increase the contact area between the finned tube 17 and the airflow outside the tube, accelerate the heat transfer rate, and further improve the waste heat recovery efficiency. Among them, the air inlet opening of the air guide hood 10 is larger than the outlet opening, which can effectively gather and guide the flue gas after heat exchange, reduce the flue gas flow resistance, and ensure the smooth discharge of flue gas. The air inlet of the air guide hood 10 is covered outside the top outlet of the finned tube 17, which can effectively prevent the flue gas from lingering in the top cavity of the furnace body 7 and reduce heat loss. The exhaust pipe 11 is sealed and connected to the outlet of the air guide hood 10 and extends vertically to the outside of the furnace body 7, which can effectively prevent the flue gas from leaking, ensure the stable delivery of flue gas to the subsequent processing process, and improve the environmental performance of the equipment operation. The blower 9 has its outlet facing the lower outer wall of the finned tube 17, allowing the ambient temperature airflow to flow from bottom to top along the outer wall of the finned tube 17. This effectively prolongs the contact heat exchange time between the airflow and the finned tube 17, improving the heating effect and heat exchange uniformity of the airflow. The conveying pipe 15 is located on the back of the furnace body 7 and its inlet is connected to its cavity. This effectively concentrates and discharges the hot airflow that has completed heat exchange and heating in the furnace body 7 cavity, ensuring the temperature stability of the airflow delivered to the external pyrolysis furnace and improving the preheating effect.

[0023] A method for using a waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace includes the following steps: Step 1: Nitrogen gas is introduced into the pyrolysis furnace body 1 through the air inlet pipe 18 to replace the internal air. The fan 2 inside the pyrolysis furnace body 1 is started. The pyrolysis furnace body 1 pyrolyzes the internal materials. The flue gas generated by pyrolysis enters the secondary combustion chamber body 3. Step 2: The low-NOx burner 13 on the side wall of the secondary combustion chamber body 3 is started, the oxygen supply mechanism 14 supplies oxygen to the interior of the secondary combustion chamber body 3, the flue gas is burned inside the secondary combustion chamber body 3, the thermometer 4 monitors the internal temperature of the secondary combustion chamber body 3 in real time, the explosion relief valve 5 relieves overpressure in the secondary combustion chamber body 3, and the ash cleaning door 6 is used for shutdown ash cleaning of the secondary combustion chamber body 3. Step 3: The flue gas after combustion in the secondary combustion chamber 3 is filtered by the filter mechanism 8 and then enters the finned tube 17. The blower 9 blows air into the furnace body 7. The airflow contacts the outer wall of the finned tube 17 for heat exchange. The heat-exchanged airflow is then transported to another pyrolysis furnace for preheating through the conveying pipe 15. Step 4: The flue gas inside the finned tube 17 is guided by the air guide hood 10 and then discharged through the exhaust pipe 11 to the subsequent treatment process.

[0024] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace, characterized in that, It includes the pyrolysis furnace body (1), fan (2), secondary combustion chamber body (3), thermometer (4), explosion relief valve (5), ash removal door (6), furnace body (7), filter mechanism (8), blower (9), air guide hood (10), exhaust pipe (11), regenerating diversion pipe (12), low nitrogen burner (13), oxygen supplementation mechanism (14), conveying pipe (15), air hole (16), finned tube (17) and air inlet pipe (18); The top cavity of the pyrolysis furnace body (1) is connected to the bottom air inlet cavity of the secondary combustion chamber body (3). A fan (2) is installed in the internal cavity of the pyrolysis furnace body (1). An air inlet pipe (18) is installed on the side wall of the pyrolysis furnace body (1). One end of the air inlet pipe (18) is connected to the internal cavity of the pyrolysis furnace body (1), and the other end of the air inlet pipe (18) extends to the outside of the pyrolysis furnace body (1). A low-NOx burner (13) and an oxygen supplementation mechanism (14) are respectively installed on the side wall of the secondary combustion chamber body (3). The low-NOx burner (13) has a combustion end that extends into the internal cavity of the secondary combustion chamber body (3), an oxygen supply mechanism (14) has an outlet end that extends into the internal cavity of the secondary combustion chamber body (3), a temperature measuring instrument (4) has a detection end that extends into the internal cavity of the secondary combustion chamber body (3), an air inlet end of the explosion relief valve (5) is connected to the internal cavity of the secondary combustion chamber body (3), and the ash removal door (6) is sealed to the side wall inspection port of the secondary combustion chamber body (3). A regenerating diversion pipe (12) is provided at the bottom of one side of the pyrolysis furnace body (1). One end of the regenerating diversion pipe (12) is connected to the center of the bottom surface inside the pyrolysis furnace body (1), and the other end of the regenerating diversion pipe (12) extends to the outside of the pyrolysis furnace body (1). A filter mechanism (8) and a finned tube (17) are arranged sequentially in the internal cavity of the furnace body (7). The air inlet of the filter mechanism (8) is connected to the air outlet of the secondary combustion chamber body (3), and the air outlet of the filter mechanism (8) is connected to the bottom air inlet of the finned tube (17). Multiple sets of air holes (16) are provided on the tube wall of the finned tube (17), and the top air outlet of the finned tube (17) is connected to the air inlet of the air guide hood (10). The air guide hood (10) is fixed to the top of the furnace body (7) and communicates with the interior of the furnace body (7). The air outlet of the air guide hood (10) is connected to one end of the exhaust pipe (11), and the other end of the exhaust pipe (11) extends to the outside of the furnace body (7). A blower (9) is provided on the side wall of the furnace body (7). The air outlet of the blower (9) extends to the internal cavity of the furnace body (7). The air outlet of the blower (9) faces the outer wall of the finned tube (17). A conveying pipe (15) is provided on the side wall of the furnace body (7). One end of the conveying pipe (15) is connected to the internal cavity of the furnace body (7), and the other end of the conveying pipe (15) extends to the outside of the furnace body (7) and communicates with the air inlet cavity of another pyrolysis furnace.

2. The waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace according to claim 1, characterized in that, The fan (2) is fixed to the top inner wall of the pyrolysis furnace body (1), and the air outlet direction of the fan (2) is towards the bottom cavity of the pyrolysis furnace body (1); the air inlet pipe (18) is located on the lower side wall of the pyrolysis furnace body (1), and the air outlet end of the air inlet pipe (18) is towards the center of the internal cavity of the pyrolysis furnace body (1).

3. The waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace according to claim 1, characterized in that, The low-NOx burner (13) and the oxygen supply mechanism (14) are both located on the back of the secondary combustion chamber body (3). The combustion end of the low-NOx burner (13) and the outlet end of the oxygen supply mechanism (14) are at the same horizontal height. The thermometer (4) is located on the upper front of the secondary combustion chamber body (3). The detection end of the thermometer (4) faces the inner cavity of the secondary combustion chamber body (3).

4. The waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace according to claim 1, characterized in that, The explosion relief valve (5) is located on the top of the secondary combustion chamber body (3), and the pressure relief direction of the explosion relief valve (5) is towards the outside and above of the secondary combustion chamber body (3); the ash removal door (6) is located on the lower side wall of the secondary combustion chamber body (3), and the bottom edge of the ash removal door (6) is flush with the bottom surface of the internal cavity of the secondary combustion chamber body (3).

5. A waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace according to claim 1, characterized in that, The filter mechanism (8) is fixed to the lower cavity of the furnace body (7), and the outer edge of the filter mechanism (8) is sealed and fitted to the inner wall of the furnace body (7); the finned tube (17) is vertically arranged along the height direction of the furnace body (7), and the bottom air inlet end of the finned tube (17) is sealed and connected to the top air outlet end of the filter mechanism (8).

6. The waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace according to claim 1, characterized in that, The air holes (16) are evenly distributed along the circumference and axial direction of the finned tube (17). The two ends of the air holes (16) are respectively connected to the internal cavity of the finned tube (17) and the internal cavity of the furnace body (7). Multiple sets of fins are provided on the outer wall of the finned tube (17). The fins are arranged at equal intervals along the axial direction of the finned tube (17).

7. A waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace according to claim 1, characterized in that, The air inlet opening of the air guide hood (10) is larger than the air outlet opening. The air inlet of the air guide hood (10) is covered outside the top air outlet of the finned tube (17). The air inlet of the exhaust pipe (11) is sealed and connected to the air outlet of the air guide hood (10). The exhaust pipe (11) extends vertically to the outside of the furnace body (7).

8. A waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace according to claim 1, characterized in that, The blower (9) is located on the front side wall of the furnace body (7), and the outlet of the blower (9) faces the lower outer wall of the finned tube (17); the conveying pipe (15) is located on the back of the furnace body (7), and the inlet of the conveying pipe (15) is connected to the internal cavity of the furnace body (7).

9. A method of using a waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace, providing a method of use for the waste heat recovery device for a secondary combustion chamber in a pyrolysis furnace as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Nitrogen gas is introduced into the pyrolysis furnace body (1) through the air inlet pipe (18) to replace the internal air. The fan (2) inside the pyrolysis furnace body (1) is started. The pyrolysis furnace body (1) pyrolyzes the internal materials. The flue gas generated by pyrolysis enters the secondary combustion chamber body (3). Step 2: The low-NOx burner (13) on the side wall of the secondary combustion chamber body (3) is started, the oxygen supply mechanism (14) supplies oxygen to the interior of the secondary combustion chamber body (3), the flue gas burns inside the secondary combustion chamber body (3), the thermometer (4) monitors the internal temperature of the secondary combustion chamber body (3) in real time, the explosion relief valve (5) relieves the overpressure of the secondary combustion chamber body (3), and the ash cleaning door (6) is used for the shutdown and ash cleaning of the secondary combustion chamber body (3); Step 3: The flue gas after combustion in the secondary combustion chamber (3) is filtered by the filter mechanism (8) and then enters the finned tube (17). The blower (9) blows air into the furnace body (7). The airflow contacts the outer wall of the finned tube (17) for heat exchange. The airflow after heat exchange is transported to another pyrolysis furnace for preheating through the conveying pipe (15). Step 4: The flue gas in the finned tube (17) is guided by the air guide hood (10) and discharged through the exhaust pipe (11) to the subsequent treatment process.

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