Three-cavity cooperative microwave pyrolysis equipment based on waste heat recovery and working method thereof

Abstract

The application provides a three-cavity cooperative microwave pyrolysis equipment based on waste heat recovery and a working method thereof, and belongs to the technical field of microwave heating. The equipment adopts longitudinally vertically distributed drying cavities, pyrolysis cavities and cooling cavities, and is communicated through air cylinder driven split closing plates between the cavities to form gravity driven vertical flow channels. The PLC and touch display module realize dynamic balance of material flow and energy flow according to temperature data fed back by thermocouples in the cavities. The equipment is integrated with a waste heat recovery module. Biogas generated by pyrolysis is introduced into the drying cavity heat exchange tube bundle for indirect heat exchange through a circulating gas path pipe group, and then is reflowed to a circulating water cooling tank for further cooling, and finally is introduced into a gas washing, drying and filtering barrel for gas washing, dehydration and multi-stage filtration to ensure that the pyrolysis gas meets the discharge standard. Through three-cavity cooperation and efficient waste heat recovery, the application improves material processing efficiency and energy utilization efficiency, and reduces overall system energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of microwave heating technology, and particularly relates to a three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery and its working method. Background Technology

[0002] Global warming and environmental pollution caused by the use of fossil fuels are becoming increasingly serious problems. Pyrolysis technology, which converts biomass into high-value-added pyrolysis oil, pyrolysis gas, and biochar in an anaerobic or hypoxic environment, has attracted widespread attention for its ability to reduce waste and utilize resources. Compared with traditional pyrolysis processes, microwave pyrolysis directly applies microwave energy to the molecules inside biomass, causing internal particle movement and generating heat. This unique heating mechanism gives it advantages such as rapid heating, high instantaneous temperature rise rate, and selective heating.

[0003] However, traditional intermittent microwave pyrolysis equipment requires frequent heating and cooling processes before and after each batch of reaction, resulting in significant waste of sensible heat from the reactor walls and insulation layer, and a high proportion of energy loss due to system thermal inertia. Existing single-cavity structures struggle to simultaneously handle the initial drying and preheating of materials and the subsequent rapid cooling, making continuous operation difficult and reducing pyrolysis production efficiency. Furthermore, the sensible heat carried by the high-temperature gases generated during pyrolysis is not effectively recovered, leading to low system energy utilization efficiency. To address these issues, this invention provides a three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a three-cavity coordinated microwave pyrolysis equipment and its working method based on waste heat recovery. By constructing a coordinated architecture integrating drying, pyrolysis, and cooling cavities, continuous processing of materials driven by gravity is achieved, improving material processing efficiency. By integrating a waste heat recovery module, the sensible heat of pyrolysis gas is recycled back to the drying stage, effectively reducing the overall energy consumption of the system. In addition, by designing a PLC and touch display module, the monitoring of the material pyrolysis temperature and the control of the coordinated operation of each cavity are realized, ensuring the dynamic balance of material flow and energy flow.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] A three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery includes an installation frame and a drying cavity, a pyrolysis cavity, and a cooling cavity installed on the installation frame from top to bottom. A waste heat recovery module is also installed on one side of the cooling cavity. A PLC and a touch display module are also installed on the installation frame. The PLC and the touch display module are electrically connected to K-type thermocouples in each cavity. The three-cavity synergistic microwave pyrolysis equipment also includes a gas washing and drying filter barrel and a high-pressure self-priming pump.

[0007] Furthermore, the drying chamber includes a drying chamber shell and a drying chamber sealing door installed on the drying chamber shell. A drying chamber split-closing plate controlled by a drying chamber cylinder is provided in the channel between the bottom of the drying chamber and the top of the pyrolysis chamber. The drying chamber cylinder is controlled by a PLC and a touch display module to perform reciprocating motion. Multiple electric heating tubes are also arranged in parallel inside the drying chamber. A heat exchange tube bundle is also provided inside the drying chamber. A water vapor outlet is provided on the side wall of the drying chamber.

[0008] Furthermore, the pyrolysis chamber includes a pyrolysis chamber shell and a pyrolysis chamber sealing door installed on the pyrolysis chamber shell. A pyrolysis chamber split-closing plate, controlled by a pyrolysis chamber cylinder, is provided in the channel between the bottom of the pyrolysis chamber and the top of the cooling chamber. The pyrolysis chamber cylinder is controlled by a PLC and a touch display module to perform reciprocating motion. The sidewall of the pyrolysis chamber is connected to multiple magnetrons through multiple rectangular waveguides. Each magnetron is equipped with an air inlet shroud and a fan on its outer side. The sidewall of the pyrolysis chamber is also provided with a gas outlet.

[0009] Furthermore, the cooling chamber includes a cooling chamber shell and a cooling chamber sealing door installed on the cooling chamber shell. The cooling chamber is provided with a discharge guide rail, and a discharge drawer is installed on the discharge guide rail. A fixed bracket is also installed in the cooling chamber, and a cooling tube bundle is arranged on the fixed bracket.

[0010] Furthermore, the waste heat recovery module includes a circulating gas path duct support, a circulating gas path assembly, and a circulating water cooling box; the circulating gas path assembly includes a circulating gas path assembly heating section, a circulating gas path assembly oil outlet section, and a circulating gas path assembly reflux condensation section; the circulating gas path duct support is fixed inside the circulating water cooling box to support the portion of the circulating gas path assembly reflux condensation section inside the circulating water cooling box.

[0011] Furthermore, the gas outlet on the side wall of the pyrolysis chamber is connected to the inlet of the heating section of the circulating gas pipeline group. The two outlets of the heating section of the circulating gas pipeline group are respectively connected to the inlet of the heat exchange tube bundle and the inlet of the oil outlet section of the circulating gas pipeline group. The outlet of the heat exchange tube bundle and the water vapor outlet on the drying chamber are both connected to the inlet of the reflux condensation section of the circulating gas pipeline group. After the circulating gas pipeline group flows through the circulating water cooling box, its outlet is connected to the inlet of the external washing gas drying filter barrel. The outlet of the oil outlet section of the circulating gas pipeline group is vertically downward connected to the air.

[0012] The cooling tube bundle inlet is connected to the high-pressure self-priming pump outlet, and the high-pressure self-priming pump inlet is connected to the circulating water cooling box outlet; the cooling tube bundle outlet is connected to the circulating water cooling box inlet via a connecting pipe.

[0013] Furthermore, the drying chamber cylinder is connected to one end of the transmission rocker arm via a hinge pin at the end of its push rod. The other end of the transmission rocker arm is fixed on the rotational long shaft of the drying chamber split-closing plate. The drying chamber cylinder is controlled by the PLC and touch display module to perform reciprocating motion, thereby driving the drying chamber split-closing plate to open to both sides or close towards the center along a predetermined trajectory via the hinge pin. The control of the pyrolysis chamber split-closing plate by the pyrolysis chamber cylinder is the same as that of the drying chamber cylinder.

[0014] Furthermore, the parts of the push rods of the drying chamber cylinder and the pyrolysis chamber cylinder that penetrate the outer shell are equipped with cut-off waveguides; the contact surfaces of the split-opening closing plates of the drying chamber and the split-opening closing plates of the pyrolysis chamber are equipped with high-temperature resistant metal wire mesh sealing strips.

[0015] Furthermore, the drying chamber sealing door and the drying chamber outer shell both adopt a sheet metal and rock wool sandwich structure; the pyrolysis chamber sealing door and the pyrolysis chamber outer shell are, from the inside out, a high-transmittance refractory lining, a porous ceramic insulation layer, and a metal shielding sheet metal; the cooling chamber sealing door and the cooling chamber outer shell are both made of metal sheet metal.

[0016] A working method for the above-mentioned three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery includes the following processes:

[0017] Place the material in the drying chamber, ensuring it covers the heating element, and close the drying chamber's sealing door. During initial equipment startup, the heating element provides auxiliary heating and dehydration to the material. Water vapor generated during the drying process flows into the circulating gas pipeline group's return condensation section under the negative pressure created by the washing gas drying filter, then sequentially enters the circulating water cooling box and the washing gas drying filter for recovery. When the K-type thermocouple inside the drying chamber detects that the material temperature reaches 100-120℃ and remains constant for a period, it indicates that the free moisture in the material has been largely removed. The PLC and touch display module drive the drying chamber cylinder to retract, opening the drying chamber's split closing plate. The material falls into the pyrolysis chamber by gravity, supported by the support plate to form a dense material layer. Then, the PLC and touch display module control the drying chamber cylinder to extend, closing the drying chamber's split closing plate, and the next batch of material is placed into the drying chamber, with the operation repeating the same process.

[0018] When the microwave source is turned on, the magnetron converts electrical energy into microwave energy, which is then uniformly fed into the pyrolysis cavity from different phases through a rectangular waveguide. The microwaves directly act on the material molecules, causing them to generate intense frictional heat. In an oxygen-free environment, chemical bonds in the material break, generating high-temperature pyrolysis oil, pyrolysis gas, and biochar. The volatilized high-temperature macromolecular pyrolysis oil flows from the gas outlet of the pyrolysis cavity into the heating section of the circulating gas pipeline group. Under gravity, it enters the oil outlet section of the circulating gas pipeline group, where it is cooled by air and collected at the outlet. The high-temperature pyrolysis gas is then dried through a gas washing process. Under the negative pressure created by the filter barrel, the gas flows into the heating section of the circulating gas pipeline group and is then introduced into the heat exchange tube bundle. The high-temperature gas flows inside the tubes, transferring sensible heat to the wet material in the drying chamber through the tube walls. Waste heat is used to pre-dry the next batch of material. The cooled pyrolysis gas flows back to the condensation section of the circulating gas pipeline group and enters the circulating water cooling box for further condensation. At the same time, a high-pressure self-priming pump drives cooling water to circulate in the circulating water cooling box, simultaneously removing the heat from the residual gas. Finally, the pyrolysis gas enters the gas washing and drying filter barrel for washing, dehydration, and multi-stage filtration, and is discharged after meeting the standards.

[0019] When the K-type thermocouple in the pyrolysis chamber detects that the material temperature reaches 600-900℃ and no gas is observed being generated at the outlet of the gas washing and drying filter, pyrolysis is complete. The PLC and touch display module control the retraction of the pyrolysis chamber cylinder and the opening of the pyrolysis chamber's split closing plate. After the solid product naturally falls into the cooling chamber, the pyrolysis chamber cylinder is driven to extend to close the split closing plate. Then, the drying chamber cylinder is controlled to retract and the drying chamber's split closing plate is opened, allowing the next batch of material to fall from the drying chamber into the pyrolysis chamber for continuous pyrolysis. The high-pressure self-priming pump drives the cooling water to circulate between the cooling tube bundle and the circulating water cooling box, carrying away the heat from the solid product. When the K-type thermocouple in the cooling chamber detects that the temperature is below 100℃, the cooling chamber sealing door is opened, the discharge drawer is pulled out, and the biochar is removed.

[0020] The present invention has the following beneficial effects:

[0021] 1. This invention transforms discrete batch operations into continuous production through the vertical gravity flow integrated design of the drying, pyrolysis, and cooling chambers, reducing the sensible heat loss of the chamber caused by frequent temperature rises and falls in traditional intermittent equipment; through the recovery of waste heat from biogas, the originally discarded sensible heat is converted into drying power, realizing the effective utilization of waste heat and reducing the microwave energy consumption per unit mass of material.

[0022] 2. This invention integrates drying, pyrolysis, cooling, and waste heat utilization into a single vertical equipment, which occupies a small area and allows multiple chambers to work together. This invention supports power adjustment and a wide range of material load fluctuations, making it applicable to a wide range of scenarios and offering high process flexibility and industrial expansion potential.

[0023] 3. In this invention, the drying, pyrolysis, and cooling chambers are clearly divided and independently designed, ensuring that the material undergoes a uniform thermal process in the pyrolysis chamber, avoiding overheating or incomplete pyrolysis, and effectively improving the stability of biochar and biogas yield. Attached Figure Description

[0024] Figure 1 This is a diaxial projection schematic diagram of the three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery as described in this invention;

[0025] Figure 2 This is a front view of the main body of the three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery as described in this invention;

[0026] Figure 3 for Figure 2 BB-direction cross-section view;

[0027] Figure 4 for Figure 2 CC-direction cross-section view.

[0028] In the diagram: 1-Top cover; 2-Drying chamber; 3-PLC and touch display module; 4-Pyrolysis chamber; 5-Cooling chamber; 6-Base; 7-Washing gas drying filter barrel; 8-Waste heat recovery module; 9-High pressure self-priming pump; 10-Support column; 201-Drying chamber sealing door; 202-Drying chamber outer shell; 203-Drying chamber cylinder; 204-Heating tube; 205-Heat exchange tube bundle; 206-Drying chamber split closing plate; 401-Pyrolysis chamber sealing door; 402-Pyrolysis chamber outer shell; 403-Pyrolysis chamber cylinder; 404-Rectangular Waveguide; 405-Magnetron; 406-Air inlet shroud; 407-Fan; 408-Panel; 409-Pyrolysis chamber split closing plate; 501-Cooling chamber sealing door; 502-Cooling chamber outer shell; 503-Connecting pipe; 504-Discharge drawer; 505-Discharge guide rail; 506-Cooling tube bundle; 507-Fixed bracket; 801-Circulating gas path duct bracket; 802a-Circulating gas path assembly heating section; 802b-Circulating gas path assembly oil outlet section; 802c-Circulating gas path assembly reflux condensation section; 803-Circulating water cooling box. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0030] like Figure 1 As shown, the three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery of the present invention includes a top cover 1, a drying cavity 2, a PLC and touch display module 3, a pyrolysis cavity 4, a cooling cavity 5, a base 6, and a support column 10.

[0031] like Figure 1As shown, the equipment adopts a longitudinal vertical distribution structure, with each cavity connected by a split-opening and closing plate controlled by a cylinder, forming a gravity-driven vertical flow continuous processing channel. The equipment is also equipped with a gas washing and drying filter barrel 7, a waste heat recovery module 8, and a high-pressure self-priming pump 9 to achieve sensible heat recovery of pyrolysis gas and ensure that the exhaust gas meets emission standards.

[0032] like Figure 1 As shown, the top cover 1 is welded from stainless steel sheet metal and is located at the very top of the equipment to fix the drying chamber 2. Four support columns 10 are provided, vertically connected between the top cover 1 and the base 6, forming a stable external frame. The base 6 is used to support the cooling chamber 5 and the waste heat recovery module 8.

[0033] like Figures 1 to 4 As shown, the drying chamber 2 is located at the top of the equipment and includes a drying chamber sealing door 201, a drying chamber outer shell 202, a drying chamber cylinder 203, an electric heating tube 204, a heat exchange tube bundle 205, and a drying chamber split-closing plate 206. The drying chamber sealing door 201 is fixed to the drying chamber outer shell 202 by a hinge, and its function is both gas sealing and microwave shielding. The drying chamber outer shell 202 adopts a sheet metal and rock wool sandwich structure to prevent heat loss. The drying chamber cylinder 203 is connected to one end of a transmission rocker arm through a hinge pin at the end of its push rod. The other end of the transmission rocker arm is fixed to the rotating long shaft of the drying chamber split-closing plate 206. The drying chamber cylinder 203 is controlled by a PLC and a touch display module 3 to reciprocate, and then drives the drying chamber split-closing plate 206 to open to both sides or close towards the center along a predetermined trajectory through the hinge pin, so as to realize the controlled gravity unloading of materials from the drying chamber 2 to the pyrolysis chamber 4.

[0034] like Figures 1 to 4As shown, three electric heating tubes 204 are arranged in parallel inside the drying chamber 2 to preheat and dehydrate the first batch of materials during the initial startup of the equipment. The inlet of the heat exchange tube bundle 205 is connected to the outlet of the heating section 802a of the circulating gas pipeline in the waste heat recovery module 8. Its function is to introduce the pyrolysis gas generated in the pyrolysis chamber 4 into the drying chamber 2, realizing the transfer of heat to the wet material. The outlet of the heat exchange tube bundle 205 and the water vapor outlet on the side of the drying chamber 2 are connected to the inlet of the return condensation section 802c of the circulating gas pipeline in the waste heat recovery module 8. Its function is to return the pyrolysis gas flowing through the heat exchange tube bundle 205 and the water vapor generated by the drying of the material in the drying chamber 2 to the circulating water cooling box 803 for cooling through the return condensation section 802c of the circulating gas pipeline. The K-type thermocouple of the drying chamber is wall-mounted and fixed inside the drying chamber 2. Its signal end passes through the outer shell 202 of the drying chamber and is electrically connected to the PLC and touch display module 3. Its probe is arranged within the coverage area of ​​the material layer to measure the real-time temperature of the material in the drying chamber 2. The drying chamber split closing plate 206 is located between the drying chamber 2 and the pyrolysis chamber 4. In actual application, the PLC and touch display module 3 control the drying chamber cylinder 203 to retract based on the real-time temperature data fed back by the K-type thermocouple of the drying chamber, and drive the drying chamber split closing plate 206 to open to both sides, so that the dried material falls vertically into the pyrolysis chamber 4 below under the action of gravity.

[0035] like Figures 1 to 4 As shown, the pyrolysis chamber 4 is located in the middle of the equipment and includes a pyrolysis chamber sealing door 401, a pyrolysis chamber outer shell 402, a pyrolysis chamber cylinder 403, a rectangular waveguide 404, a magnetron 405, an air inlet hood 406, a fan 407, a support plate 408, and a pyrolysis chamber split closing plate 409. The pyrolysis chamber sealing door 401 is fixed to the pyrolysis chamber outer shell 402 by hinges. From the inside out, the pyrolysis chamber sealing door 401 and the pyrolysis chamber outer shell 402 consist of a high-transmittance refractory lining, a porous ceramic insulation layer, and a metal shielding sheet metal, which serves to reduce heat dissipation and microwave leakage inside the pyrolysis chamber 4. The bottom of the pyrolysis chamber 4 is equipped with a pyrolysis chamber split-closing plate 409, which is controlled to open and close by a pyrolysis chamber cylinder 403. The pyrolysis chamber cylinder 403 is connected to one end of a transmission rocker arm via a hinge pin at the end of its push rod. The other end of the transmission rocker arm is fixed on the long rotating shaft of the pyrolysis chamber split-closing plate 409. The pyrolysis chamber cylinder 403 is controlled by a PLC and a touch display module 3 to perform reciprocating motion. After the pyrolysis reaction is completed, the hinge pin can drive the pyrolysis chamber split-closing plate 409 to open to both sides along a predetermined trajectory, allowing the residual solids from the pyrolysis to fall naturally into the cooling chamber 5 below. The pyrolysis chamber 4 is also equipped with a support plate 408, which is used to stably receive the material falling from above and assist in forming a dense stacked bed.

[0036] like Figures 1 to 4As shown, the sidewall of the pyrolysis chamber 4 is connected to five magnetrons 405 via five rectangular waveguides 404, with a power adjustment range of 0–7.5 kW. Each magnetron 405 is equipped with an air inlet shroud 406 and a fan 407. The magnetron 405 converts DC power into microwave power, which is transmitted to the pyrolysis chamber 4 via the rectangular waveguides 404. The airflow generated by the fan 407 is delivered to the magnetron 405 via the air inlet shroud 406, and its working heat is removed by forced convection. The K-type thermocouple of the pyrolysis chamber penetrates the outer shell 402 of the pyrolysis chamber through a special high-temperature resistant sealing connector and is fixed inside the pyrolysis chamber 4 in a wall-mounted manner. It is electrically connected to the PLC and touch display module 3. Its probe is arranged within the coverage area of ​​the material layer to measure the real-time temperature of the material inside the pyrolysis chamber 4.

[0037] like Figures 1 to 4 As shown, the gas outlet on the side of the pyrolysis chamber 4 is connected to the inlet of the heating section 802a of the circulating gas pipeline in the waste heat recovery module 8. One outlet of the heating section 802a is connected to the inlet of the heat exchange tube bundle 205 in the drying chamber 2. Under the negative pressure of the pipeline caused by the washing gas drying filter barrel 7, the pyrolysis gas is introduced into the heat exchange tube bundle 205 through the heating section 802a to achieve heat transfer to the wet material. The other outlet of the heating section 802a is connected to the inlet of the oil outlet section 802b. The outlet of the oil outlet section 802b is vertically downward to the air. After the high-temperature macromolecular bio-oil evaporates from the heating section 802a, it flows into the oil outlet section 802b under the action of gravity, condenses upon encountering air at the outlet, and finally flows out from the outlet of the oil outlet section 802b.

[0038] like Figures 1 to 4As shown, the cooling chamber 5 is located at the bottom of the equipment and includes a cooling chamber sealing door 501, a cooling chamber outer shell 502, a connecting pipe 503, a discharge drawer 504, a discharge guide rail 505, a cooling tube bundle 506, and a fixing bracket 507. The cooling chamber sealing door 501 is fixed to the cooling chamber outer shell 502 by hinges. Both are made of sheet metal and serve to provide gas sealing and microwave shielding. A K-type thermocouple for the cooling chamber is wall-mounted and passes through the cooling chamber outer shell 502 to be fixed inside the cooling chamber 5. Its probe is arranged within the coverage area of ​​the material layer to measure the real-time temperature of the material inside the cooling chamber 5, thereby determining the discharge time. The cooling chamber 5 is equipped with a discharge guide rail 505, on which a discharge drawer 504 is installed. The discharge drawer 504 is used to receive solid residues falling from the pyrolysis chamber 4, and the discharge guide rail 505 ensures that the discharge drawer 504 can be smoothly pushed into or pulled out of the cooling chamber 5 along a fixed path. To accelerate cooling, a fixed bracket 507 is installed inside the cooling chamber 5. A cooling tube bundle 506 is arranged on the fixed bracket 507. The outlet of the cooling tube bundle 506 is connected to the inlet of the circulating water cooling box 803 in the waste heat recovery module 8 via a connecting pipe 503. The inlet of the cooling tube bundle 506 is connected to the outlet of the high-pressure self-priming pump 9. The outlet of the circulating water cooling box 803 and the inlet of the high-pressure self-priming pump 9 form a closed-loop circulation. The high-pressure self-priming pump 9 drives the cooling water in the circulating water cooling box 803 to flow within the cooling tube bundle 506, removing the sensible heat of the solid products through forced heat exchange.

[0039] like Figures 1 to 4 As shown, the waste heat recovery module 8 is fixed to the bottom of the equipment and located on one side of the cooling chamber 5, and includes a circulating gas duct support 801, a circulating gas pipe assembly 802, and a circulating water cooling box 803. The circulating gas pipe assembly 802 includes a circulating gas pipe assembly heating section 802a, a circulating gas pipe assembly oil outlet section 802b, and a circulating gas pipe assembly return condensation section 802c. The circulating gas duct support 801 is fixed inside the circulating water cooling box 803 and is used to support the portion of the circulating gas pipe assembly return condensation section 802c within the circulating water cooling box 803. The inlet of the heating section 802a of the circulating gas pipeline is connected to the gas outlet of the pyrolysis chamber 4. The two outlets of the heating section 802a of the circulating gas pipeline are connected to the inlet of the heat exchange tube bundle 205 and the inlet of the oil outlet section 802b of the circulating gas pipeline, respectively. The outlet of the heat exchange tube bundle 205 and the water vapor outlet of the drying chamber 2 are both connected to the inlet of the reflux condensation section 802c of the circulating gas pipeline. After the circulating gas pipeline reflux condensation section 802c flows through the circulating water cooling box 803, its outlet is connected to the inlet of the external washing gas drying filter barrel 7. The outlet of the oil outlet section 802b of the circulating gas pipeline is vertically downward connected to the air.

[0040] The pyrolysis gas generated in the pyrolysis chamber 4 at 400-600℃ enters the heating section 802a of the circulating gas pipeline group from the gas outlet of the pyrolysis chamber 4 under the negative pressure of the pipeline group caused by the gas washing and drying filter tank 7. It first flows through the heat exchange tube bundle 205 in the drying chamber 2, transferring heat to the wet material in the drying chamber 2. After cooling, the pyrolysis gas returns to the circulating water cooling box 803 through the condensation section 802c of the circulating gas pipeline group for secondary cooling. The cooled gas finally enters the gas washing and drying filter tank 7 through the pipeline, and is discharged after condensation, gas washing and multi-stage filtration. The circulating water cooling box 803 is fixed on the base 6 and is connected to the cooling tube bundle 506 and the high-pressure self-priming pump 9 in the cooling chamber 5 through the connecting pipe 503. Its function is to drive the flow of cooling water through the high-pressure self-priming pump 9 to remove the heat from the cooling chamber 5 and the condensation section 802c of the circulating gas pipeline group.

[0041] The signal input terminals of the PLC and touch display module 3 are electrically connected to the K-type thermocouples in each cavity to collect temperature data in each cavity in real time. The signal output terminals are electrically connected to the magnetron 405 and each cylinder to control the start and stop of the microwave and the opening and closing of each split-type closing plate.

[0042] Furthermore, all sheet metal connections in this invention are made using continuous welding. Cut-off waveguides are installed at the points where the push rods of the drying chamber cylinder 203 and the pyrolysis chamber cylinder 403 penetrate the outer shell. High-temperature resistant metal wire mesh sealing strips are provided on the contact surfaces of the drying chamber split-closing plate 206 and the pyrolysis chamber split-closing plate 409 to reduce external microwave leakage during equipment operation.

[0043] The working principle of the above-mentioned three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery is as follows:

[0044] Solid granular material weighing 5-20 kg is placed in drying chamber 2, ensuring that the material covers the heating element 204, and the drying chamber sealing door 201 is closed. During the initial startup phase, the material is assisted in being heated and dehydrated by the three heating elements 204. The water vapor generated during the drying process flows into the circulating gas pipeline group's return condensation section 802c under the negative pressure created by the washing gas drying filter barrel 7, and then sequentially enters the circulating water cooling box 803 and the washing gas drying filter barrel 7 for recovery. When the K-type thermocouple in the drying chamber detects that the material temperature in drying chamber 2 reaches 100-120℃ and remains constant for a period of time, it indicates that the free moisture in the material has been largely removed. The drying chamber cylinder 203 is then driven to retract via the PLC and touch display module 3, opening the drying chamber's split closing plate 206. The material falls into the pyrolysis chamber 4 by gravity, where it is supported by the support plate 408 to form a dense material layer. Then, the PLC and touch display module 3 control the drying chamber cylinder 203 to extend, close the drying chamber double-opening closing plate 206, and put the next batch of materials into the drying chamber 2. The operation is the same as above.

[0045] When the microwave source is turned on, five magnetrons 405 convert electrical energy into microwave energy with a frequency of 2450MHz and a power of 0-7.5kW, which is then uniformly fed into the pyrolysis chamber 4 from different phases through five rectangular waveguides 404. The microwaves directly act on the material molecules, causing them to generate intense frictional heat. Because the outer shell 402 of the pyrolysis chamber is equipped with a high-transmittance lining and a porous ceramic insulation layer, the microwave energy is locked in the material area, achieving rapid heating from the inside out. In an oxygen-free environment, the chemical bonds of the material break, generating high-temperature pyrolysis oil, pyrolysis gas, and biochar. The volatilized high-temperature macromolecular pyrolysis oil flows from the gas outlet of the pyrolysis chamber 4 into the heating section 802a of the circulating gas pipeline group, and enters the oil outlet section 802b of the circulating gas pipeline group under the action of gravity. After being cooled by air, it is collected at the outlet of the oil outlet section 802b of the circulating gas pipeline group. High-temperature pyrolysis gas flows into the heating section 802a of the circulating gas pipeline group under the negative pressure created by the gas washing and drying filter barrel 7. It is then introduced into the heat exchange tube bundle 205 in the drying chamber 2. The high-temperature gas flows inside the tubes and transfers sensible heat to the wet material in the drying chamber 2 through the tube walls. Waste heat is used to complete the pre-drying of the next batch of material. The cooled pyrolysis gas enters the circulating water cooling box 803 for further condensation through the reflux condensation section 802c of the circulating gas pipeline group. At the same time, the high-pressure self-priming pump 9 drives the cooling water to circulate in the circulating water cooling box 803, simultaneously removing the heat of the residual gas. Finally, the pyrolysis gas enters the gas washing and drying filter barrel 7 for gas washing, dehydration and multi-stage filtration to ensure that the pyrolysis gas meets the emission standards.

[0046] When the temperature of the material in the pyrolysis chamber 4 reaches 600-900℃ and no gas is observed being generated at the outlet of the gas washing and drying filter tank 7, pyrolysis is complete. At this point, the pyrolysis chamber cylinder 403 is retracted via the PLC and touch display module 3, opening the pyrolysis chamber split closing plate 409. After the solid product naturally falls into the cooling chamber 5, the pyrolysis chamber cylinder 403 is extended to close the pyrolysis chamber split closing plate 409. Then, the drying chamber cylinder 203 is retracted, opening the drying chamber split closing plate 206, allowing the next batch of material to fall from the drying chamber into the pyrolysis chamber 4 for continuous pyrolysis. The high-pressure self-priming pump 9 drives cooling water to circulate between the cooling tube bundle 506 in the cooling chamber 5 and the circulating water cooling box 803, carrying away the heat from the solid product. When the temperature in the cooling chamber 5 is observed to be below 100℃, the cooling chamber sealing door 501 is opened, the discharge drawer 504 is pulled out, and the biochar is removed.

[0047] Throughout the process, the PLC and touch display module 3 collect data from the K-type thermocouples in the drying chamber, the pyrolysis chamber, and the cooling chamber in real time to identify the pre-dehydration reference, the pyrolysis reaction endpoint, and the safe discharge temperature.

[0048] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A three-cavity synergistic microwave pyrolysis device based on waste heat recovery, characterized in that, The equipment includes a mounting frame and a drying chamber (2), a pyrolysis chamber (4), and a cooling chamber (5) mounted on the mounting frame from top to bottom. A waste heat recovery module (8) is also installed on one side of the cooling chamber (5). A PLC and a touch display module (3) are also installed on the mounting frame. The PLC and the touch display module (3) are electrically connected to the K-type thermocouples in each chamber. The three-chamber synergistic microwave pyrolysis equipment also includes a gas washing and drying filter barrel (7) and a high-pressure self-priming pump (9). The drying chamber (2) includes a drying chamber shell (202) and a drying chamber sealing door (201) installed on the drying chamber shell (202). A drying chamber split-closing plate (206) controlled by a drying chamber cylinder (203) is provided in the channel between the bottom of the drying chamber (2) and the top of the pyrolysis chamber (4). The drying chamber cylinder (203) is controlled by a PLC and a touch display module (3) to perform reciprocating motion. Multiple electric heating tubes (204) are also arranged in parallel inside the drying chamber (2). A heat exchange tube bundle (205) is also provided inside the drying chamber (2). A water vapor outlet is provided on the side wall of the drying chamber (2).

2. The three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery according to claim 1, characterized in that, The pyrolysis chamber (4) includes a pyrolysis chamber shell (402) and a pyrolysis chamber sealing door (401) installed on the pyrolysis chamber shell (402). A pyrolysis chamber split-closing plate (409) controlled by a pyrolysis chamber cylinder (403) is provided in the channel between the bottom of the pyrolysis chamber (4) and the top of the cooling chamber (5). The pyrolysis chamber cylinder (403) is controlled by a PLC and a touch display module (3) to perform reciprocating motion. The side wall of the pyrolysis chamber (4) is connected to multiple magnetrons (405) through multiple rectangular waveguides (404). Each magnetron (405) is equipped with an air inlet hood (406) and a fan (407) on its outer side. The side wall of the pyrolysis chamber (4) is also provided with a gas outlet.

3. The three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery according to claim 2, characterized in that, The cooling chamber (5) includes a cooling chamber shell (502) and a cooling chamber sealing door (501) installed on the cooling chamber shell (502). The cooling chamber (5) is provided with a discharge guide rail (505) and a discharge drawer (504) is installed on the discharge guide rail (505). A fixed bracket (507) is also installed in the cooling chamber (5) and a cooling tube bundle (506) is arranged on the fixed bracket (507).

4. The three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery according to claim 3, characterized in that, The waste heat recovery module (8) includes a circulating gas duct support (801), a circulating gas pipeline assembly (802), and a circulating water cooling box (803); the circulating gas pipeline assembly (802) includes a circulating gas pipeline assembly heating section (802a), a circulating gas pipeline assembly oil outlet section (802b), and a circulating gas pipeline assembly reflux condensation section (802c); the circulating gas duct support (801) is fixed inside the circulating water cooling box (803) to support the portion of the circulating gas pipeline assembly reflux condensation section (802c) inside the circulating water cooling box (803).

5. The three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery according to claim 4, characterized in that, The gas outlet of the side wall of the pyrolysis chamber (4) is connected to the inlet of the heating section (802a) of the circulating gas pipeline group. The two outlets of the heating section (802a) of the circulating gas pipeline group are connected to the inlet of the heat exchange tube bundle (205) and the inlet of the oil outlet section (802b) of the circulating gas pipeline group, respectively. The outlet of the heat exchange tube bundle (205) and the water vapor outlet on the drying chamber (2) are both connected to the inlet of the reflux condensation section (802c) of the circulating gas pipeline group. After the reflux condensation section (802c) of the circulating gas pipeline group flows through the circulating water cooling box (803), its outlet is connected to the inlet of the external washing gas drying filter barrel (7). The outlet of the oil outlet section (802b) of the circulating gas pipeline group is vertically downward connected to the air. The inlet of the cooling tube bundle (506) is connected to the outlet of the high-pressure self-priming pump (9), and the inlet of the high-pressure self-priming pump (9) is connected to the outlet of the circulating water cooling box (803); the outlet of the cooling tube bundle (506) is connected to the inlet of the circulating water cooling box (803) through the connecting pipe (503).

6. The three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery according to claim 2, characterized in that, The drying chamber cylinder (203) is connected to one end of the transmission rocker arm via a hinge pin at the end of its push rod. The other end of the transmission rocker arm is fixed on the long rotating shaft of the drying chamber split-closing plate (206). The drying chamber cylinder (203) is controlled by the PLC and the touch display module (3) to perform reciprocating motion, and then drives the drying chamber split-closing plate (206) to open to both sides or close to the center along a predetermined trajectory via the hinge pin. The control of the pyrolysis chamber cylinder (403) on the pyrolysis chamber split-closing plate (409) is the same as that of the drying chamber cylinder (203).

7. The three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery according to claim 6, characterized in that, The parts of the push rods of the drying chamber cylinder (203) and the pyrolysis chamber cylinder (403) that penetrate the outer shell are equipped with cut-off waveguides; the contact surfaces of the drying chamber split closing plate (206) and the pyrolysis chamber split closing plate (409) are equipped with high-temperature resistant metal wire mesh sealing strips.

8. The three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery according to claim 3, characterized in that, The drying chamber sealing door (201) and the drying chamber shell (202) are both made of sheet metal and rock wool sandwich structure; the pyrolysis chamber sealing door (401) and the pyrolysis chamber shell (402) are, from the inside out, a high-transmittance refractory lining, a porous ceramic insulation layer, and a metal shielding sheet metal; the cooling chamber sealing door (501) and the cooling chamber shell (502) are both made of metal sheet metal.

9. A method for operating the three-cavity synergistic microwave pyrolysis equipment based on waste heat recovery as described in claim 5, characterized in that, The process includes the following: Place the material in the drying chamber (2), ensuring that the material covers the heating tube (204), and close the drying chamber sealing door (201). In the initial stage of equipment startup, the heating tube (204) provides auxiliary heating and dehydration for the material. The water vapor generated during the drying process flows into the reflux condensation section (802c) of the circulating gas pipeline group under the negative pressure created by the washing gas drying filter (7), and then enters the circulating water cooling box (803) and the washing gas drying filter (7) in sequence for recovery. When the K-type thermocouple inside the drying chamber detects that the material temperature in the drying chamber (2) reaches the specified value, the material is dried. When the temperature reaches 100-120℃ and is kept constant for a period of time, it indicates that the free moisture in the material has been basically removed. The PLC and touch display module (3) drive the drying chamber cylinder (203) to retract, open the drying chamber double-opening closing plate (206), and the material falls into the pyrolysis chamber (4) by gravity. The support plate (408) supports and forms a dense material layer. Then, the PLC and touch display module (3) control the drying chamber cylinder (203) to extend, close the drying chamber double-opening closing plate (206), and put the next batch of material into the drying chamber (2). The operation is the same as above. When the microwave source is turned on, the magnetron (405) converts electrical energy into microwave energy, which is fed into the pyrolysis cavity (4) uniformly from different phases through the rectangular waveguide (404). The microwaves directly act on the material molecules, causing them to generate intense frictional heat. The chemical bonds of the material break in an oxygen-free environment, generating high-temperature pyrolysis oil, pyrolysis gas, and biochar. The volatilized high-temperature macromolecular pyrolysis oil flows from the gas outlet of the pyrolysis cavity (4) into the heating section (802a) of the circulating gas pipeline group, and enters the oil outlet section (802b) of the circulating gas pipeline group under the action of gravity. After being cooled by air, it is collected at the outlet of the oil outlet section (802b) of the circulating gas pipeline group. The high-temperature pyrolysis gas is dried and filtered in the gas washing and drying filter barrel ( 7) The gas flows into the heating section (802a) of the circulating gas pipeline under negative pressure, and is then introduced into the heat exchange tube bundle (205). The high-temperature gas flows in the tube and transfers sensible heat to the wet material in the drying chamber (2) through the tube wall. The waste heat is used to complete the pre-drying of the next batch of material. The pyrolysis gas after cooling enters the circulating water cooling box (803) through the reflux condensation section (802c) of the circulating gas pipeline for further condensation. At the same time, the high-pressure self-priming pump (9) drives the cooling water to circulate in the circulating water cooling box (803) and simultaneously removes the heat of the residual gas. Finally, the pyrolysis gas enters the gas washing and drying filter barrel (7) for gas washing, dehydration and multi-stage filtration, and is discharged after meeting the standards. When the K-type thermocouple in the pyrolysis chamber (4) detects that the temperature of the material reaches 600-900℃ and no gas is observed to be generated at the outlet of the gas washing and drying filter barrel (7), the pyrolysis is completed. The pyrolysis chamber cylinder (403) is retracted by the PLC and the touch display module (3), the pyrolysis chamber double-opening closing plate (409) is opened, and after the solid product falls naturally into the cooling chamber (5), the pyrolysis chamber cylinder (403) is driven to extend to close the pyrolysis chamber double-opening closing plate (409), and then the drying is controlled. The cavity cylinder (203) retracts, opening the drying chamber's split closing plate (206), allowing the next batch of material to fall from the drying chamber into the pyrolysis chamber (4) for continuous pyrolysis; the high-pressure self-priming pump (9) drives cooling water to circulate between the cooling tube bundle (506) and the circulating water cooling box (803), carrying away the heat of the solid product; when the temperature detected by the K-type thermocouple in the cooling chamber (5) is below 100°C, the cooling chamber sealing door (501) is opened, the discharge drawer (504) is pulled out, and the biochar is taken out.

Images