A microwave-assisted high-temperature cracking device

Abstract

The present invention discloses a microwave-assisted high-temperature cracking device, including a microwave reactor and a feeding system. The microwave reactor includes a metal head, a metal cavity, a resonant cavity, a circular waveguide, a rectangular waveguide and a magnetron arranged from top to bottom; an absorbing material plate is fixed between the metal cavity and the resonant cavity, and a droplet micronizing feeder and a discharge port with adjustable spray height are provided on the metal head. The droplet micronizing feeder is used to spray fine droplets onto the upper surface of the absorbing material plate to perform a high-temperature cracking reaction. The present invention uses the metal head, the metal cavity and the absorbing material plate as a reaction site after being sealed by a flange, which not only realizes the flash heating process of the absorbing material plate but also effectively avoids the leakage of the reactant caused by the rupture of the reactor at high temperature. Through the circulation process of the material to be cracked in the outer jacket of the waveguide at the bottom of the device, it can not only preheat the material to be cracked but also reduce the heat transfer from the high-temperature metal reactor to the microwave generator, thereby realizing the effective circulation of energy.

Description

Technical Field

[0001] The invention relates to the field of high-temperature vaporization and high-temperature cracking, and in particular to a microwave-assisted heating high-temperature cracking device. Background Art

[0002] Microwave heating has significant advantages and has been widely used in metallurgy, chemical industry, medicine and other fields. Chinese patent CN104341298A applies microwave assisted heating and spray heat exchange coupling technology to the vaporization and cracking of high-boiling-point materials with continuity and high efficiency. At present, the materials of the reaction material carrier in microwave assisted heating cracking devices at home and abroad are mainly wave-transmitting materials, such as quartz, ceramics, etc. Chinese patent CN104341298A uses quartz crucible as a reactor, but the mechanical strength of quartz material is low. When the quartz crucible is in a high-temperature and complex environment, the strength and sealing performance of the device are difficult to maintain the stable operation of the device, and the leakage of raw materials and cracking gas products is prone to occur, which poses a serious safety hazard. This problem seriously restricts the amplification and industrial application of microwave assisted heating cracking devices.

[0003] High temperature environment will have an adverse effect on the microwave generator. Chinese patent CN208590129U reduces the heat transfer from the high temperature cavity to the microwave generator through a ventilation cavity composed of a wave-transmitting isolation window and a ventilation waveguide, but its application temperature is not high and the heat conducted by the high temperature cavity is not effectively utilized, resulting in energy waste. Summary of the invention

[0004] In view of the problems existing in the microwave high temperature heating device in the prior art, the purpose of the present invention is to provide a new type of microwave assisted heating high temperature cracking device which has a simple structure, high microwave heating efficiency and can effectively avoid the influence of the high temperature working environment on the device structure.

[0005] In order to solve the above technical problems existing in the prior art, the technical solution provided by the present invention is:

[0006] A novel microwave-assisted high-temperature cracking device comprises: a microwave reactor and a feeding system. The microwave reactor comprises: a metal head, a metal cavity, an absorbing material plate, a temperature controller and a temperature measuring element, a resonant cavity, a circular waveguide with a jacket, a wave-transmitting baffle, a rectangular waveguide, and a magnetron. The feeding system comprises: a raw material tank, a droplet micronizing feeder, a circulation pump, and a feeding pump. The metal head, the metal cavity, the resonant cavity, the circular waveguide, the rectangular waveguide, and the magnetron are arranged from top to bottom, the metal head is connected to the metal cavity by a flange, the absorbing material plate is fixed between the metal cavity and the resonant cavity by a flange, and the upper surface of the absorbing material plate is used as a reaction site. The temperature measuring element is placed on the upper surface of the wave-absorbing material plate and is externally connected to a temperature controller. The jacketed circular waveguide is connected to the bottom of the resonance cavity through a flange. The wave-transmitting baffle is located below the jacketed circular waveguide. The rectangular waveguide is located below the wave-transmitting baffle, and the wave-transmitting baffle is fixed between the jacketed circular waveguide and the rectangular waveguide through a flange. The magnetron is connected to the rectangular waveguide through bolts and nuts.

[0007] Furthermore, a heat exchange jacket is provided on the outer side of the circular waveguide, and an inlet and an outlet are provided on the heat exchange jacket. The liquid to be cracked is introduced into the inlet of the heat exchange jacket. While the liquid to be cracked cools the circular waveguide, the preheated liquid to be cracked is discharged from the outlet of the heat exchange jacket.

[0008] Furthermore, the bottom outlet of the raw material tank is divided into two routes, one of which is connected to the inlet of the droplet micronization feeder through a pipeline through a feed pump, and the other is connected to the inlet of the heat exchange jacket on the outside of the circular waveguide side through a pipeline. The outlet of the heat exchange jacket on the outside of the circular waveguide side is further connected to the top inlet of the raw material tank through a pipeline. The cracking liquid circulates between the raw material tank and the heat exchange jacket on the outside of the circular waveguide side under the conveying action of the circulation pump to be preheated.

[0009] As a preferred embodiment, the metal head is made of stainless steel, and a discharge port is provided on the top of the metal head, which is connected to a receiving tank. The droplet micronization feeder includes a nozzle and a metal hose connected to the nozzle inlet pipe. A curved circular tube track is welded inside the top side wall of the metal head. The metal hose of the droplet micronization feeder is sealed and passes through the curved circular tube track and is connected to the feeding system. The height of the nozzle is adjusted by the curved circular tube track to control the distance H from the droplet micronization feeder to the upper surface of the absorbing material plate, where H=R·tan(θ / 2), where R is the radius of the area to be cracked, and θ is the atomization angle of the droplet micronization feeder spray. The droplet micronization feeder is connected to a feed pump, such as a plunger metering pump, through a pipeline outside the tube. The droplet micronization feeder is used to spray fine droplets onto the upper surface of the absorbing material plate for high-temperature cracking reaction.

[0010] As a preferred solution, the metal cavity is a cylinder made of stainless steel, with a metal seal connected to the top by a flange, and the metal seal, metal cavity and absorbing material plate are sealed as a reaction site. The metal cavity is provided with a first nitrogen inlet and a temperature measuring port, and a temperature measuring element is provided above the absorbing material plate. The power connection end of the temperature measuring element passes outward from the temperature measuring port and is connected to a temperature controller for controlling the temperature of the reaction site on the upper surface of the absorbing material plate. The temperature sensing point of the temperature measuring element is placed between the center and the edge of the absorbing material plate, and the temperature measuring element is a thermocouple or an optical fiber temperature sensor.

[0011] As a preferred solution, the absorbing material plate is fixed between the metal cavity and the resonant cavity, and the height of the absorbing material plate from the inner wall of the bottom of the resonant cavity is n / 2 times (n=1~10) of the microwave wavelength, which can maximize the microwave utilization efficiency. The absorbing material plate is made of absorbing materials composed of silicon carbide, activated carbon, iron, cobalt, nickel-loaded alumina and molecular sieve catalyst, and can adopt various sealing methods in the field, such as flange sealing, welding sealing, thread sealing, etc. It can be used as a reaction site and can effectively prevent reactants or products from leaking to the bottom of the device. A temperature measuring element is provided above the absorbing material plate, and the temperature measuring element is connected to a temperature controller to control the temperature of the reaction site on the upper surface of the absorbing material plate. The temperature sensing point is placed between the center and the edge of the upper surface of the absorbing material plate, and a nitrogen outlet is provided on the side of the resonant cavity.

[0012] As a preferred solution, the thickness of the absorbing material plate is 0.5 cm-1.5 cm.

[0013] As a preferred solution, the side of the resonance cavity is provided with a nitrogen outlet, and the bottom is opened, and the hole diameter is adapted to the diameter of the circular waveguide; the upper end of the circular waveguide is inserted into the opening at the bottom of the resonance cavity, and the side of the upper end of the circular waveguide is connected to the bottom of the resonance cavity through a flange.

[0014] As a preferred solution, a second nitrogen inlet is provided at the bottom side of the circular waveguide, and the length of the circular waveguide is n / 2 times (n=1-5) the wavelength of the microwave conducted by the circular waveguide. The liquid of the material to be cracked is passed through the heat exchange jacket on the outside of the circular waveguide side, which can not only preheat the liquid to be cracked but also reduce the heat transfer from the high-temperature metal wall of the reactor to the microwave generator, reduce the temperature of the circular waveguide with the jacket in the working state, and protect the magnetron. The circular waveguide with the jacket is connected to the bottom of the resonant cavity through a flange, and its material can be any one of stainless steel, aluminum, or alloy.

[0015] As a preferred solution, the wave-transmitting baffle is located between the jacketed circular waveguide and the rectangular waveguide. The wave-transmitting baffle is made of polytetrafluoroethylene, mica and other materials, and can adopt various sealing methods in the relevant field, such as flange sealing, welding sealing, threaded sealing, etc., which can effectively transmit microwaves while further isolating heat to protect the magnetron.

[0016] As a preferred solution, the rectangular waveguide is a national standard BJ26 waveguide, the magnetron is a water-cooled magnetron, and a refrigerant circulates inside. The refrigerant material can be ethylene glycol-water type refrigerant or glycerin-water type refrigerant, and its temperature is maintained between -20°C and -10°C. The magnetron is connected to the waveguide by bolts and nuts, and its power can be selected according to actual needs.

[0017] As a preferred solution, thermal insulation material is attached around the metal head, metal cavity, and resonant cavity, which is composed of thermal insulation cotton containing ceramic fibers to reduce radiation heat dissipation of the reactor, and a metal wire mesh is wrapped around the device to isolate microwaves.

[0018] The beneficial effects of the present invention are as follows: the present invention uses a metal head, a metal cavity and an absorbing material plate as a reaction site after being sealed by a flange, which not only realizes the flash heating process of the absorbing material plate but also effectively avoids the leakage of reactants caused by the rupture of the reactor during the high-temperature reaction. By adjusting the distance between the droplet micronization feeder and the upper surface of the absorbing material plate, when the micron-scale to-be-decomposed material under different feed amounts hits the area with uniform temperature distribution on the surface of the high-temperature bed, the heat exchange load per unit area can still be guaranteed to be stable, thereby realizing the flash heating and efficient decomposition of the to-be-decomposed material. Through the circulation process of the to-be-decomposed material at the outer jacket of the waveguide (i.e., circular waveguide) with a jacket at the bottom of the device, it is possible to preheat the to-be-decomposed material and reduce the heat transfer from the high-temperature metal reactor to the microwave generator, thereby realizing the effective utilization of energy circulation. The magnetron is cooled by using a low-temperature refrigerant instead of normal-temperature water to ensure the normal operation of the magnetron in a high-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Explanation of the reference numerals: 1-1 metal head, 1-11 discharge port, 1-2 metal cavity, 1-12 first nitrogen inlet, 1-13 temperature measuring port, 1-3 wave absorbing material plate, 1-4 temperature controller, 1-5 temperature measuring element, 1-6 resonant cavity, 1-14 nitrogen outlet, 1-7 circular waveguide, 1-15 second nitrogen inlet, 1-8 wave-transparent partition, 1-9 rectangular waveguide, 1-10 magnetron, 2-1 raw material tank, 2-2 droplet micronization feeder, 2-3 circulation pump, 2-4 feed pump.

[0021] Figure 2 It is a schematic diagram of the upper surface of the absorbing material plate 1-3. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0023] Comparison Figure 1As shown, a novel microwave-assisted heating high-temperature cracking device includes a microwave reactor and a feeding system.

[0024] The microwave reactor includes a metal end cap 1-1, a metal cavity 1-2, a resonant cavity 1-6, a circular waveguide 1-7, a rectangular waveguide 1-9 and a magnetron 1-10 arranged from top to bottom. The metal end cap 1-1 is connected to the top of the metal cavity 1-2 by a flange, the wave absorbing material plate 1-3 is fixed between the metal cavity 1-2 and the resonant cavity 1-6 by a flange, the circular waveguide 1-7 is connected to the bottom of the resonant cavity 1-6 by screws, the rectangular waveguide 1-9 is fixed to the bottom of the circular waveguide 1-7 by a flange, and the magnetron 1-10 is connected to the rectangular waveguide 1-9 by bolts and nuts. The metal end cap 1-1 is provided with a droplet micronizing feeder 2-2 with adjustable tube length and a discharge port 1-11, and the droplet micronizing feeder 2-2 is used to spray fine droplets onto the upper surface of the wave absorbing material plate 1-3 so as to perform a high temperature cracking reaction.

[0025] Comparison Figure 1 In the figure, the droplet micronization feeder 2-2 includes a nozzle and a metal hose connected to the nozzle inlet pipe. A curved circular tube track is welded inside the top side wall of the metal head 1-1. The metal hose of the droplet micronization feeder 2-2 is sealed and passes through the curved circular tube track and then connected to the feeding system. Figure 1 The bottom end of the curved circular tube track opens vertically downward. The distance H between the droplet micronizing feeder 2-2 and the upper surface of the wave absorbing material plate 1-3 is controlled, H=R·tan(θ / 2), where R is the radius of the area to be cracked, and θ is the atomization angle of the droplet micronizing feeder 2-2 spray.

[0026] A heat exchange jacket is provided on the outer side of the circular waveguide 1-7, and an inlet and an outlet are provided on the heat exchange jacket. The liquid to be cracked is introduced into the inlet of the heat exchange jacket, and the liquid to be cracked cools the circular waveguide 1-7 while the preheated liquid to be cracked is discharged from the outlet of the heat exchange jacket. Figure 1 A second nitrogen inlet 1-15 is provided on the bottom side of the circular waveguide 1-7.

[0027] The feeding system includes a raw material tank 2-1, a circulation pump 2-3 and a feeding pump 2-4. The bottom outlet of the raw material tank 2-1 is divided into two routes, one of which is connected to the metal hose inlet of the droplet micronization feeder 2-2 through a pipeline through the feeding pump 2-4, and the other is connected to the inlet of the heat exchange jacket on the outside of the side of the circular waveguide 1-7 through the circulation pump 2-3. The outlet of the heat exchange jacket on the outside of the side of the circular waveguide 1-7 is further connected to the top inlet of the raw material tank 2-1 through a pipeline. The feed liquid to be cracked circulates and flows between the raw material tank 2-1 and the heat exchange jacket on the outside of the side of the circular waveguide 1-7 for preheating under the conveying action of the circulation pump 2-3.

[0028] Comparison Figure 1A first nitrogen inlet 1-12 and a temperature measuring port 1-13 are provided on the metal cavity 1-2, and a temperature measuring element 1-5 is provided above the absorbing material plate 1-3. The power connection end of the temperature measuring element 1-5 passes outward from the temperature measuring port 1-13 and is connected to a temperature controller 1-4, which is used to control the temperature of the reaction place on the surface of the absorbing material plate 1-3. The temperature sensing point of the temperature measuring element 1-5 is placed between the center and the edge of the absorbing material plate 1-3, and the temperature measuring element 1-5 is a thermocouple or an optical fiber temperature sensor.

[0029] Comparison Figure 1 The side of the resonant cavity 1-6 is provided with a nitrogen outlet 1-14, and the bottom is opened, and the aperture is adapted to the diameter of the circular waveguide 1-7; the upper end of the circular waveguide 1-7 is inserted into the bottom opening of the resonant cavity 1-6, and the upper end side of the circular waveguide 1-7 is connected to the bottom of the resonant cavity 1-6 through a flange. A wave-transmitting baffle 1-8 is also provided between the circular waveguide 1-7 and the rectangular waveguide 1-9. The wave-transmitting baffle 1-8 is made of polytetrafluoroethylene or mica material, and the wave-transmitting baffle 1-8 is connected and fixed between the circular waveguide 1-7 and the rectangular waveguide 1-9 through a flange.

[0030] The rectangular waveguide is located at the bottom of the device. The microwaves generated by the magnetron are transmitted through the rectangular waveguide and through the wave-transmitting baffle to the jacketed circular waveguide. The wave-transmitting baffle can be made of wave-transmitting materials such as quartz and polytetrafluoroethylene. A heat exchange jacket is provided around the circular waveguide, and the inside of the heat exchange jacket passes through the liquid to be cracked. The top of the circular waveguide is connected to the bottom of the resonant cavity through a flange. An absorbing material plate (such as silicon carbide) is provided 11 cm away from the inner wall of the bottom of the resonant cavity as a heat source for auxiliary heating. It is fixed between the metal cavity and the resonant cavity through a flange. The metal cavity and the resonant cavity are made of stainless steel, and there is thermal insulation cotton around them to reduce the radiation heat dissipation of the device.

[0031] Application Implementation Case

[0032] In this embodiment, Figure 1 A novel microwave-assisted high-temperature cracking device is shown in the figure and applied to the cracking of biomass fuel, taking microwave-assisted cracking of ricinoleic acid ester as an example. The specific steps are as follows:

[0033] 1. Open the nitrogen valve and introduce nitrogen into the device at a flow rate of 300 ml / min. After the air inside the device is evacuated, set the reaction temperature of temperature controllers 1-4 to between 450-550°C, and start the microwave power supply to start heating;

[0034] 2. When the temperature of the reaction bed reaches 100°C, start the circulation pump 2-3. After the bed temperature stabilizes at the set temperature and the temperature of the raw material tank 2-1 reaches 180°C, start the feed pump 2-4 to transport the methyl ricinoleate in the raw material tank 2-1 to the droplet micronizing feeder 2-2. The methyl ricinoleate is sprayed on the upper surface of the high-temperature silicon carbide bed in the form of micro droplets.

[0035] 3. Methyl ricinoleate in the form of micro-droplets contacts the upper surface of the high-temperature silicon carbide bed and rapidly heats up, cracking to generate a variety of products, which are collected in the condensation collection tank. The condensation temperature is set to -20 °C, and the collected products are weighed with an electronic balance.

[0036] Embodiment: A droplet micronizing feeder 2-2 with an aperture of 0.1 mm and an atomization angle θ of 80° is selected. The distance between the droplet micronizing feeder 2-2 and the upper surface of the absorbing material plate 1-3 is 5 cm. The radius R of the area to be cracked on the upper surface of the absorbing material plate 1-3 is 4.3 cm. The absorbing material plate 1-3 (using a silicon carbide plate) is 1 cm thick, and the height from the inner wall of the bottom of the resonant cavity 1-6 is 3 / 2 times the microwave wavelength (19 cm). The microwave power is 1200 W. The area to be cracked (such as Figure 2 The average temperature of the raw material tank 2-1 is 470°C, and the methyl ricinoleate is preheated by circulating between the heat exchange jacket on the outside of the side of the circular waveguide 1-7 under the conveying action of the circulating pump 2-3. The length of the circular waveguide 1-7 is 1 times the wavelength of the microwave conducted by the circular waveguide (18 cm). The methyl ricinoleate is preheated to 180°C. The methyl ricinoleate with a mass flow rate of 14 g / min is conveyed to the droplet micronization feeder 2-2 by the feed pump 2-4. The methyl ricinoleate is sprayed on the upper surface of the absorbing material plate 1-3 in the form of micro droplets by the droplet micronization feeder 2-2. The micro droplets are flash-heated and cracked, and the cracking products enter the receiving tank through the discharge port 1-11 above the metal head 1-1. The results of the embodiment are as follows: the microwave heating of the absorbing material plate can reach the set reaction temperature after 15 minutes. After the cracking experiment, the mass percentage of the target product, heptanal, is 31.4%; the mass percentage of methyl undecenoate is 34.9%. Compared with the experiment of preheating the solution to be cracked by electric heating, the energy saving is 20%.

[0037] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. A microwave-assisted heating high-temperature cracking device, characterized in that: The invention comprises a microwave reactor and a feeding system, wherein the microwave reactor comprises a metal end cap (1-1), a metal cavity (1-2), a resonant cavity (1-6), a circular waveguide (1-7), a rectangular waveguide (1-9) and a magnetron (1-10) arranged from top to bottom; the metal end cap (1-1) is connected to the top of the metal cavity (1-2) via a flange, the wave absorbing material plate (1-3) is fixed between the metal cavity (1-2) and the resonant cavity (1-6) via a flange, and the circular waveguide (1-7) is connected to the top of the metal cavity (1-2) via a screw. The nail is connected below the resonant cavity (1-6), the rectangular waveguide (1-9) is fixed below the circular waveguide (1-7) via a flange, and the magnetron (1-10) is connected to the rectangular waveguide (1-9) via bolts and nuts; wherein a droplet micronizing feeder (2-2) and a discharge port (1-11) with adjustable spray height are provided on the metal end cap (1-1), and the droplet micronizing feeder (2-2) is used to spray fine droplets onto the upper surface of the absorbing material plate (1-3) to perform a high-temperature cracking reaction; A heat exchange jacket is provided on the outer side of the circular waveguide (1-7), and an inlet and an outlet are provided on the heat exchange jacket. The liquid to be cracked is introduced into the inlet of the heat exchange jacket. While the liquid to be cracked cools the circular waveguide (1-7), the preheated liquid to be cracked is discharged from the outlet of the heat exchange jacket. The droplet micronizing feeder (2-2) comprises a nozzle and a metal hose connected to the nozzle inlet pipe, a curved circular tube track is welded inside the top side wall of the metal seal (1-1), and the metal hose of the droplet micronizing feeder (2-2) is connected to the feeding system after passing through the curved circular tube track in a sealed manner, and the distance H from the droplet micronizing feeder (2-2) to the upper surface of the wave-absorbing material plate (1-3) is controlled, H=R·tan(θ / 2), wherein R is the radius of the area of ​​the to-be-cracking region, and θ is the atomization angle of the droplet micronizing feeder (2-2); The feeding system comprises a raw material tank (2-1), a circulation pump (2-3) and a feeding pump (2-4); the bottom outlet of the raw material tank (2-1) is divided into two routes, one route is connected to the metal hose inlet of the droplet micronization feeder (2-2) through a pipeline through the feeding pump (2-4), and the other route is connected to the inlet of the heat exchange jacket on the outside of the side of the circular waveguide (1-7) through the circulation pump (2-3). The outlet of the heat exchange jacket on the outside of the side of the circular waveguide (1-7) is then connected to the top inlet of the raw material tank (2-1) through a pipeline. The feed liquid to be cracked circulates and flows between the raw material tank (2-1) and the heat exchange jacket on the outside of the side of the circular waveguide (1-7) under the conveying action of the circulation pump (2-3) to be preheated.

2. A microwave-assisted heating pyrolysis device according to claim 1, characterized in that: The metal cavity (1-2) is provided with a first nitrogen inlet (1-12) and a temperature measuring port (1-13); a temperature measuring element (1-5) is provided above the absorbing material plate (1-3); an electrical connection end of the temperature measuring element (1-5) extends outward from the temperature measuring port (1-13) and is connected to a temperature controller (1-4) for controlling the temperature of a reaction site on the surface of the absorbing material plate (1-3); a temperature sensing point of the temperature measuring element (1-5) is located between the center and the edge of the absorbing material plate (1-3); and the temperature measuring element (1-5) is a thermocouple or an optical fiber temperature detector.

3. A microwave-assisted heating pyrolysis device according to claim 1, characterized in that: The height of the absorbing material plate (1-3) from the bottom inner wall of the resonant cavity (1-6) is n / 2 times the wavelength of the microwave, where n=1-10; the thickness of the absorbing material plate (1-3) is 0.5 cm-1.5 cm, and its material is a plate having both microwave absorption performance and high-temperature sealing performance, and is selected from a silicon carbide plate.

4. A microwave-assisted heating pyrolysis device according to claim 1, characterized in that: The resonant cavity (1-6) is provided with a nitrogen outlet (1-14) on the side, and has an opening at the bottom, the diameter of which matches the diameter of the circular waveguide (1-7); the upper end of the circular waveguide (1-7) is inserted into the opening at the bottom of the resonant cavity (1-6), and the upper end side of the circular waveguide (1-7) is connected to the bottom of the resonant cavity (1-6) via a flange.

5. A microwave-assisted heating pyrolysis device according to claim 1, characterized in that: A second nitrogen inlet (1-15) is provided at the bottom side of the circular waveguide (1-7), and the length of the circular waveguide (1-7) is n / 2 times the wavelength of microwaves conducted by the circular waveguide, where n=1-5.

6. A microwave-assisted heating pyrolysis device according to claim 1, characterized in that: A wave-transmitting baffle (1-8) is also provided between the circular waveguide (1-7) and the rectangular waveguide (1-9); the wave-transmitting baffle (1-8) is made of polytetrafluoroethylene or mica material; the wave-transmitting baffle (1-8) is connected and fixed between the circular waveguide (1-7) and the rectangular waveguide (1-9) via a flange.

7. A microwave-assisted heating pyrolysis device according to claim 1, characterized in that: A low-temperature freezing liquid flows inside the magnetron (1-10), and the temperature of the freezing liquid is between -20°C and -10°C; the material of the low-temperature freezing liquid is ethylene glycol-water freezing liquid or glycerin-water freezing liquid.

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