A system and method for producing biochar using cement kiln inert gas

Abstract

The application belongs to the technical field of biomass utilization, and discloses a system and method for producing biomass charcoal by using cement kiln inert gas, wherein the system comprises a feeding module, a pyrolysis gas treatment module and a biomass charcoal storage module, further comprises a drying and pyrolysis device and a cement kiln inert gas supply module, the pyrolysis gas outlet of the drying and pyrolysis device is connected to the pyrolysis gas treatment module, the solid product outlet of the drying and pyrolysis device is connected to the biomass charcoal storage module, the drying and pyrolysis device comprises a drying device, a screw conveying device and a rotary pyrolysis furnace, a spiral coil is fixed to the inner wall of the rotary furnace body of the rotary pyrolysis furnace, one end of the spiral coil is connected to the cement kiln inert gas supply module to receive high-temperature inert gas, and the other end is introduced into the drying device after being cooled by a cooling structure, the inlet of the drying device receives biomass raw materials supplied by the feeding module, the outlet of the drying device is sealingly connected to the inlet of the screw conveying device, and the outlet of the screw conveying device is in communication with the inner cavity of the rotary furnace body. The application introduces the waste gas of high-temperature inert gas into the inside of the biomass pyrolysis furnace for direct heating, which is high in heating efficiency and ensures the stability of the operation of the pyrolysis device.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass utilization, and in particular relates to a system and method for producing biochar by utilizing cement kiln inert gas. Background Art

[0002] Biomass primarily refers to firewood, agricultural and forestry crops, agricultural and forestry food processing residues, animal manure, and household waste. Biomass energy, as a clean energy source, is the only renewable energy source with both a carbon source and a physical carrier. It can be stored and converted into high-quality solid, liquid, and gaseous fuels. The Earth produces 173 billion tons of biomass annually through photosynthesis, containing energy equivalent to 10 to 20 times the world's total energy consumption. However, its utilization rate is currently less than 3%. Furthermore, biomass energy is renewable, low-pollution, widely distributed, and can be flexibly produced into biofuels. Consequently, countries around the world are increasingly interested in its applications.

[0003] Biomass pyrolysis is the process by which biomass, in the absence of oxygen or oxygen, absorbs heat at relatively low temperatures (300-700°C) to undergo thermal cracking, breaking down the biomass's internal macromolecular structure and converting it into solid coke, combustible gases (methane, ethylene, carbon monoxide), and liquid biomass oils (tar, wood vinegar). Biochar can completely replace high-quality "green" fuels such as traditional coal and liquefied petroleum gas. Its smokeless, odorless, high calorific value, and long combustion time make it a suitable alternative to coke, reducing coal use and controlling air pollution, making it a popular choice for biochar applications.

[0004] At present, biomass rotary pyrolysis furnaces mainly use external indirect heating to prevent oxygen from entering the system. The external indirect heating method of the rotary pyrolysis furnace has low heat transfer efficiency, resulting in energy waste and low production efficiency and high operating costs, making biomass fuel charcoal difficult to use as an industrial fuel alternative. Summary of the Invention

[0005] The purpose of the present invention is to provide a system for producing biochar using cement kiln inert gas, which is used to solve the technical problems in the prior art of low heat transfer efficiency, energy waste, low production efficiency and high operating costs caused by the external indirect heating method of the rotary pyrolysis furnace.

[0006] The system for making biochar using cement kiln inert gas includes a feeding module, a pyrolysis gas treatment module and a biochar storage module, and also includes a drying pyrolysis device and a cement kiln inert gas supply module. The pyrolysis gas outlet of the drying pyrolysis device is connected to the pyrolysis gas treatment module, and the solid product outlet of the drying pyrolysis device is connected to the biochar storage module. The drying pyrolysis device includes a drying device, a screw conveying device and a rotary pyrolysis furnace. A spiral coil is fixed on the inner wall of the rotary furnace body of the rotary pyrolysis furnace. One end of the spiral coil is connected to the cement kiln inert gas supply module to receive high-temperature inert gas, and the other end is cooled by a cooling structure and then passed into the drying device. The inlet of the drying device receives the biomass raw material supplied by the feeding module, and the outlet of the drying device is sealed with the inlet of the screw conveying device. The outlet of the screw conveying device is connected to the inner cavity of the rotary furnace body.

[0007] Preferably, the rotary pyrolysis furnace also includes a feed end cover and a discharge end cover, and the inner sides of the feed end cover and the discharge end cover are provided with annular protrusions, and the annular protrusions are rotatably connected with the corresponding rotating rings, and the rotating rings are fixedly connected to the two ends of the rotary furnace body, respectively. An annular cavity 1 is provided in the annular protrusion, and an annular cavity 2 is provided in the rotating ring. The outer edge of the rotating ring extends into the annular protrusion, and the annular cavity 1 is connected to the annular cavity 2, and a sealing structure is provided between the rotating ring and the annular protrusion. The annular protrusion has an interface 1 for connecting to the external air pipe, and the rotating ring has an interface 2 for connecting to the spiral coil.

[0008] Preferably, a spiral conveying structure is provided in the rotary furnace body, and the spiral conveying structure includes spiral heat-conducting blades, the outer edges of the spiral heat-conducting blades are welded to the spiral coil, and the spiral heat-conducting blades divide the inner cavity of the rotary furnace body into a spiral cavity.

[0009] Preferably, a feed hole is provided in the center of the feed end cover, and the spiral conveying structure also includes a transmission shaft located at the spiral heat-conducting blade, one end of the transmission shaft passes through the feed hole and extends into the cylinder of the spiral conveying device, and a spiral heat-insulating blade is provided in the cylinder, and the spiral heat-insulating blade is fixed to the part of the transmission shaft extending into the spiral conveying device, the outer edge of the spiral heat-insulating blade fits into the cylinder and divides the inner cavity of the cylinder to form a spiral cavity, and the rotation direction of the spiral heat-insulating blade is opposite to that of the spiral heat-conducting blade.

[0010] Preferably, the end face of the discharge end cover is provided with a pyrolysis gas outlet, and the pyrolysis gas outlet discharges the pyrolysis gas outward. The end face of the annular protrusion of the discharge end cover is also provided with a ring sleeve that is sleeved on the outside of the rotating cylinder, and the solid product outlet is fixed under the ring sleeve. The side wall of the discharge end of the rotating cylinder is provided with a discharge groove connected to the solid product outlet, and the discharge groove and the ring sleeve are sealed by a seal, and the seal is fixed on the outside of the discharge groove.

[0011] Preferably, a conveying mechanism is provided in the box body of the drying device, an inlet is provided above the feed end of the box body of the drying device, and an outlet is provided below the discharge end of the box body, the upper part of the feed end of the box body is connected to an air outlet pipe 2 for outputting drying gas, and the lower part of the discharge end of the box body is connected to an air inlet pipe 2 for inputting drying gas, and the drying gas is formed by cooling the high-temperature inert gas output by the rotary pyrolysis furnace through a cooling module; the cooling module includes an air mixing device, the air inlet end of the air mixing device is respectively connected to the air outlet pipe 1 and the blower for inputting lower temperature inert gas, and the air outlet end of the air mixing device is connected to the air inlet pipe 2.

[0012] Preferably, the pyrolysis gas treatment module includes a liquid separation cooler connected to the pyrolysis gas outlet and a combustible gas purification tower, a water seal tank, a gas holder and a combustion furnace connected in sequence from the gas outlet of the liquid separation cooler through pipelines. The pyrolysis gas treatment module also includes an infusion pump connected to the liquid outlet of the liquid separation cooler, and the combustion furnace is connected to an oxygen distribution fan for inputting oxygen.

[0013] Preferably, the exhaust port of the combustion furnace is connected to the air inlet of the air mixing device via a pipeline, and the gas obtained after combustion is sent to the air mixing device to supplement the inert gas. The cooling module also includes an air-to-air heat exchanger. The gas cabinet is connected to the combustion furnace via an air supply pipeline. The air outlet pipe 1 and the air supply pipeline both pass through the air-to-air heat exchanger.

[0014] Preferably, the cement kiln inert gas supply module includes a preheater, and the exhaust gas outlet of the preheater is connected to the spiral coil inside the rotary pyrolysis furnace through an air intake duct and a high-temperature fan.

[0015] The present invention also provides a method for producing biochar using cement kiln inert gas, which uses the above-mentioned system for producing biochar using cement kiln inert gas and includes the following steps:

[0016] 1. The high-temperature inert gas generated by the preheater is sequentially passed into the rotary pyrolysis furnace, the air mixing device and the drying device before being discharged;

[0017] 2. Inputting biomass raw materials into the drying and pyrolysis device, and performing drying and pyrolysis reactions in sequence;

[0018] 3. The biochar enters the biochar collection and storage module for storage, and the pyrolysis gas enters the pyrolysis gas treatment module for gas-liquid separation, purification and combustion treatment;

[0019] Fourth, the gas after pyrolysis combustion is sent to the air mixing device to generate sufficient drying gas, and then the drying gas is introduced into the drying process to finally dry the biomass raw materials;

[0020] Among them, high-temperature inert gas at 350°C is introduced into the spiral coil to heat the rotary pyrolysis furnace. The temperature of the high-temperature inert gas output from the rotary pyrolysis furnace is reduced to 300°C, and then the temperature is controlled at 200°C after passing through the air mixing device and air distribution to form drying gas, which is introduced into the drying device for drying.

[0021] The advantages of the present invention are that the waste gas of about 350°C at the outlet of the preheater, which is mainly inert gas, is introduced into the biomass pyrolysis furnace, heat is transferred inside the rotary pyrolysis furnace, and spiral heat-conducting blades are used to contact and heat the biological raw materials, thereby achieving high heating efficiency and ensuring the stability of the pyrolysis device operation.

[0022] The used inert gas at about 300℃ is controlled at about 200℃ after air distribution, thereby forming a lower temperature drying gas. Directly introducing the drying gas into the drying furnace can ultimately achieve the drying and preheating of the biomass raw materials and form an oxygen-deficient atmosphere at the discharge end, and use a spiral conveying device to complete the delivery of the biomass raw materials and the 200℃ inert gas into the rotary pyrolysis furnace in an oxygen-deficient atmosphere.

[0023] This invention utilizes inert gas generated by the cement kiln preheater as a heat source. The biomass pyrolysis system can reduce the energy consumption of boilers and other equipment, as well as the heat source required to generate it. This reduces both equipment investment and operating costs. The preheater's high-temperature exhaust gas temperature is around 350°C, with minimal fluctuations. This provides a stable heat source, further facilitating the slow, low-temperature pyrolysis of biomass and increasing the yield of biomass fuel charcoal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a structural schematic diagram of a system for producing biochar using cement kiln inert gas.

[0025] Figure 2 for Figure 1 Schematic diagram of the structure of the drying and pyrolysis device in the structure shown.

[0026] Figure 3 for Figure 2 Schematic diagram of the internal structure of the structure shown.

[0027] Figure 4 for Figure 2 Schematic diagram of the structure of the feed end cover in the structure shown.

[0028] Figure 5 for Figure 2 Schematic diagram of the structure of the discharge end cover in the structure shown.

[0029] The markings in the accompanying drawings are: 1. Feeding belt, 2. Raw material bin, 3. Frequency conversion metering feeder, 4. Drying device, 401. Box, 402. Conveying mechanism, 403. Inlet pipe 2, 404. Outlet pipe 2, 5. Rotary pyrolysis furnace, 501. Cylinder, 502. Rotary furnace body, 503. Feed end cover, 504. Outlet end cover, 505. Ring sleeve, 506. Solid product outlet, 507. Drive gear ring, 508. Outlet pipe 1, 509. Inlet pipe 1, 510. Pyrolysis gas outlet, 511. Spiral coil, 5 12. Spiral heat-conducting blades, 513. Drive shaft, 514. Spiral insulation blades, 515. Rotating ring, 516. Annular protrusion, 517. Discharge chute, 6. Slag cooler, 7. Coal storage bin, 8. Liquid separation cooler, 9. Infusion pump, 10. Combustible gas purification tower, 11. Water seal tank, 12. Gas cabinet, 13. Preheater, 14. High-temperature fan, 15. Air-to-air heat exchanger, 16. Air mixing device, 17. Combustion furnace, 18. Blower, 19. Oxygen distribution fan, 20. Bag dust collector, 21. Induced draft fan, 22. Chimney. DETAILED DESCRIPTION

[0030] The specific implementation methods of the present invention will be further explained in detail below through the description of embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0031] like Figure 1-Figure 5 As shown, the present invention provides a system for making biochar using cement kiln inert gas, which includes a feeding module, a drying and pyrolysis device, a pyrolysis gas treatment module, a cement kiln inert gas supply module and a biochar collection and storage module. The pyrolysis gas outlet 510 of the drying and pyrolysis device is connected to the pyrolysis gas treatment module, and the solid product outlet 506 of the drying and pyrolysis device is connected to the biochar collection and storage module. The drying and pyrolysis device includes a drying device 4, a screw conveying device and a rotary pyrolysis furnace 5. A spiral coil 511 is fixed to the inner wall of the rotary furnace body 502 of the rotary pyrolysis furnace 5. One end of the spiral coil 511 is connected to the cement kiln inert gas supply module to receive high-temperature inert gas, and the other end is cooled by a cooling structure and then passed into the drying device 4. The inlet of the drying device 4 receives the biomass raw material supplied by the feeding module. The outlet of the drying device 4 is sealed with the inlet of the screw conveying device, and the outlet of the screw conveying device is connected to the inner cavity of the rotary furnace body 502.

[0032] The cement kiln inert gas supply module includes a preheater 13. An air intake is provided at the exhaust outlet of the preheater 13. An air intake duct is constructed based on the air volume, and a double-gate valve is installed on the duct to control the air flow. A high-temperature fan 14 is installed on the air inlet duct 509. The high-temperature inert gas generated by the preheater 13 is introduced into the rotary pyrolysis furnace 5 through the high-temperature fan 14. Combustion in the cement kiln system's preheater 13 produces inert gas at approximately 350°C. This system delivers this high-temperature inert gas to the rotary pyrolysis furnace 5 via the air inlet duct 509, where it is used to heat the biomass and achieve pyrolysis. This heating method uses the high-temperature inert gas delivery structure to directly heat the biomass feedstock within the rotary furnace body 502, overcoming the low heat transfer efficiency and energy waste of indirect heating methods. Furthermore, the inert gas itself contains very little oxygen, so even contact with the biomass feedstock has little impact on the pyrolysis process. This ensures high heating efficiency while ensuring stable operation of the pyrolysis unit.

[0033] The rotary pyrolysis furnace 5 also includes a feed end cover 503 and a discharge end cover 504. The inner sides of each of the feed end cover 503 and the discharge end cover 504 are provided with an annular protrusion 516. The annular protrusion 516 is rotatably connected to a corresponding rotating ring 515. The rotating ring 515 is fixedly connected to both ends of the rotary furnace body 502. The annular protrusion 516 has an annular cavity 1, and the rotating ring 515 has an annular cavity 2. The outer edge of the rotating ring 515 extends into the annular protrusion 516. The annular cavity 1 is connected to the annular cavity 2, and a sealing structure is provided between the rotating ring 515 and the annular protrusion 516. The annular protrusion 516 has an interface 1 for connecting to an external air pipe, and the rotating ring 515 has an interface 2 for connecting to the spiral coil 511. This structure prevents direct contact between the inert gas and the biomass feedstock. This can not only prevent a large amount of inert gas from mixing with the pyrolysis gas and reducing the combustion effect after the pyrolysis gas output, but also further utilize the inert gas outputted by the pyrolysis furnace at a still relatively high temperature.

[0034] The rotary furnace body 502 is fixedly sleeved with a driving gear ring 507, which is in transmission connection with the driving device of the rotary pyrolysis furnace 5 through the gear meshing effect. The rotary furnace body 502 is internally provided with a spiral conveying structure, which comprises spiral heat-conducting blades 512, the outer edges of the spiral heat-conducting blades 512 are welded to the spiral coil 511, and the spiral heat-conducting blades 512 divide the inner cavity of the rotary furnace body 502 into spiral cavities. The interface one on the discharge end cover 504 is connected to the gas inlet pipe one 509 for inputting high-temperature inert gas, and the interface one on the feeding end cover 503 is connected to the gas outlet pipe one 508 for outputting high-temperature inert gas. This structure allows the high-temperature inert gas to be heated through the spiral coil 511 and the spiral heat-conducting blades 512 connected thereto, and the spiral heat-conducting blades 512 increase the contact surface with the biomass raw materials and increase the heating efficiency. At the same time, when the rotary furnace body 502 is driven to rotate, the spiral heat-conducting blades 512 can also move the biomass raw materials towards the discharge end while turning the rotary furnace body 502, thereby achieving the effect of automatically and continuously conveying materials.

[0035] The feeding end cover 503 is provided with a feeding hole in the center, and the spiral conveying structure further comprises a transmission shaft 513 located in the spiral heat-conducting blades 512. One end of the transmission shaft 513 penetrates the feeding hole and extends into the cylinder body 501 of the spiral conveying device. The cylinder body 501 is provided with spiral heat-insulating blades 514, which are fixed to the part of the transmission shaft 513 extending into the spiral conveying device. The outer edges of the spiral heat-insulating blades 514 are attached to the cylinder body 501 and divide the inner cavity of the cylinder body 501 into spiral cavities. The rotation direction of the spiral heat-insulating blades 514 is opposite to that of the spiral heat-conducting blades 512. This structure allows the biomass raw materials output by the drying device 4 to be conveyed to the rotary furnace body 502 by the spiral heat-insulating blades 514 rotating synchronously with the rotary furnace body 502. The two rotate synchronously, and the conveying speed ratio of the spiral heat-insulating blades 514 and the spiral heat-conducting blades 512 can be set by the corresponding spiral blade spacing ratio. Unlike the spiral heat-conducting blades 512, the spiral heat-insulating blades 514 automatically convey the heat medium raw materials and have a certain heat-insulating effect, reduce the heat transfer from the rotary pyrolysis furnace 5 to the drying device 4, and ensure the stable temperature difference between the cavities.

[0036] The end surface of the discharge end cover 504 is provided with a pyrolysis gas outlet 510, which discharges pyrolysis gas outward. The end surface of the annular protrusion 516 of the discharge end cover 504 is also provided with a ring sleeve 505 that is sleeved outside the rotating cylinder 501. The solid product outlet 506 is fixed below the ring sleeve 505. The side wall of the discharge end of the rotating cylinder 501 is provided with a discharge groove 517 that is connected to the solid product outlet 506. The discharge groove 517 and the ring sleeve 505 are sealed by a seal, and the seal is fixed to the outside of the discharge groove 517. This structure allows the pyrolyzed material inside to be directly discharged after the discharge groove 517 is aligned and connected with the solid product outlet 506 when the rotary furnace body 502 rotates. In other states, the ring sleeve 505 and the seal seal the discharge groove 517 to prevent the pyrolysis gas from leaking out.

[0037] The drying device 4 has a conveying mechanism 402 disposed within the housing 401. The housing 401 of the drying device 4 has an inlet disposed above the feed end and an outlet disposed below the discharge end. The upper portion of the feed end of the housing 401 is connected to a second outlet pipe 404 for outputting drying gas, and the lower portion of the discharge end of the housing 401 is connected to a second inlet pipe 403 for inputting drying gas. The drying gas is formed by cooling the high-temperature inert gas outputted from the rotary pyrolysis furnace 5 via a cooling module. The cooling module includes an air mixing device 16, the inlet end of which is respectively connected to the first outlet pipe 508 and the blower 18 for inputting lower-temperature inert gas, and the outlet end of the air mixing device 16 is connected to the second inlet pipe 403. The conveying mechanism 402 includes a plurality of conveyor belts arranged from top to bottom, and the discharge end of each conveyor belt is located at the feed end of the conveyor belt below. This structure realizes the input of drying gas from the outlet position, which flows from bottom to top in a closed environment, and achieves drying and preheating effects at the same time. Moreover, the drying gas is an inert gas with a relatively high temperature, and can also blow the external air entering the drying device 4 upward, ensuring that the biomass raw materials output by the drying device 4 are in an oxygen-deficient atmosphere, thereby ensuring the stability of the pyrolysis process.

[0038] The pyrolysis gas treatment module includes a liquid separation cooler 8 connected to the pyrolysis gas outlet 510 and a combustible gas purification tower 10, a water seal tank 11, a gas cabinet 12 and a combustion furnace 17 connected in sequence from the gas outlet of the liquid separation cooler 8 through pipelines. The pyrolysis gas treatment module also includes an infusion pump 9 connected to the liquid outlet of the liquid separation cooler 8, and the combustion furnace 17 is connected to an oxygen distribution blower 19 for inputting oxygen. The combustion furnace 17 is also provided with a backup fuel input port for inputting backup fuel (such as diesel). The above structure can separate the liquid substances mixed into the pyrolysis gas in a high-temperature environment, and complete the purification and water washing of the combustible pyrolysis gas, ensuring that the subsequent combustion process is stable and reliable, and avoiding the generation of a large amount of harmful gases.

[0039] The exhaust port of the combustion furnace 17 is connected to the air inlet of the air mixing device 16 via a pipeline, and the gas obtained after combustion (mainly inert gas) is sent to the air mixing device 16 to supplement the inert gas. The cooling module also includes an air-to-air heat exchanger 15. The gas cabinet 12 is connected to the combustion furnace 17 via an air supply pipeline. The air outlet pipe 508 and the air supply pipeline both pass through the air-to-air heat exchanger 15. Since the pyrolysis gas will be cooled during the separation and purification process, the ventilation air heat exchanger 15 realizes heat exchange between the high-temperature inert gas in the air outlet pipe 508 and the treated pyrolysis gas in the air supply pipe. On the one hand, the pyrolysis gas is preheated, which is conducive to its full combustion in the combustion furnace 17. On the other hand, the temperature of the high-temperature inert gas input into the air mixing device 16 is reduced, which is conducive to meeting the temperature requirements of the drying gas after air mixing and reducing the amount of mixed inert gas at a lower temperature or the temperature requirement.

[0040] The feeding module includes a feeding belt 1, a raw material bin 2, and a variable frequency metering feeder 3. The discharge end of the feeding belt 1 is located above the top opening of the raw material bin 2, and the outlet at the bottom of the raw material bin 2 is located at the feed port of the variable frequency metering feeder 3. The discharge port of the variable frequency metering feeder 3 is located at the entrance of the drying device 4. The second outlet pipe 404 is connected to the bag filter 20 and the induced draft fan 21 in sequence, and then to the chimney 22. The biochar storage module includes a slag cooler 6 and a charcoal storage bin 7. The biochar output from the rotary pyrolysis furnace 5 is cooled in the slag cooler 6 and then transported to the charcoal storage bin 7 for storage.

[0041] Based on the above system, the present invention also provides a method for producing biochar using cement kiln inert gas, which includes the following steps.

[0042] 1. The high-temperature inert gas generated by the preheater 13 is sequentially passed into the rotary pyrolysis furnace 5, the air mixing device 16 and the drying device 4 and then discharged.

[0043] At the exhaust gas outlet of the preheater 13, high-temperature inert gas is obtained through the air intake duct, and the high-temperature inert gas is introduced into the rotary pyrolysis furnace 5 from the air inlet pipe 509 through the high-temperature fan 14 for heating. After the high-temperature inert gas is output from the rotary pyrolysis furnace 5, it is mixed with the inert gas at a lower temperature to form a drying gas at a lower temperature. The drying gas is then input into the drying device 4 and finally discharged to the outside.

[0044] The initial high-temperature inert gas temperature is approximately 350°C, with the inlet and outlet air volumes controlled by a double-gate valve on the air intake duct. A high-temperature induced draft fan 21 introduces the approximately 350°C high-temperature inert gas into the spiral coil 511 to heat the rotary pyrolysis furnace 5. The high-temperature inert gas output from the rotary pyrolysis furnace 5 is cooled to approximately 300°C. It then passes through the air mixing device 16, where it is distributed and controlled to approximately 200°C, forming a dry gas. This dry gas is then introduced into the drying device 4 for drying.

[0045] 2. Input biomass raw materials into the drying and pyrolysis device, and carry out drying and pyrolysis reactions in sequence.

[0046] The feeding module transports biomass raw materials to the inlet of the drying device 4. The drying gas contacts the biomass raw materials in the drying device 4 to achieve drying and preheating of the biomass raw materials, and at the same time, the air flowing into the drying device 4 is brought out upward. Since the inert gas produced by the reaction is mainly composed of nitrogen, nitrogen oxides, carbon dioxide and a small amount of oxygen, the oxygen content is only about 1.2%, so the inert gas density is greater. After continuously passing into the box 401 of the drying device 4, the oxygen-containing air with lower density will be discharged upward, so that the biomass raw materials discharged from the drying device 4 can be in an oxygen-deficient atmosphere.

[0047] Biomass feedstock is delivered to the rotary pyrolysis furnace 5 via a spiral conveyor, isolated from the outside world. This ensures an oxygen-deficient atmosphere within the furnace. Simultaneously, the temperature within the rotary furnace body 502, heated by high-temperature inert gas, rises to a pyrolysis temperature exceeding 300°C. Spiral heat-conducting blades 512 contact and heat the biomass feedstock while guiding the pyrolyzing biomass toward the discharge port. By the time the biomass feedstock reaches the discharge port, it has been fully pyrolyzed into biochar. The generated pyrolysis gas is discharged through the pyrolysis gas outlet 510, and the biochar is discharged through the solid product outlet 506.

[0048] 3. The biochar enters the biochar collection and storage module for storage, and the pyrolysis gas enters the pyrolysis gas treatment module for gas-liquid separation, purification and combustion treatment.

[0049] The biochar output from the rotary pyrolysis furnace 5 is cooled in the slag cooler 6 and then transported to the charcoal storage bin 7 for storage. For the pyrolysis gas, this method separates the liquid substances mixed into the pyrolysis gas under high temperature environment through gas-liquid separation, then completes the purification and water washing of the combustible pyrolysis gas and stores it in the gas cabinet 12. As needed, the pyrolysis gas after water washing and cooling is transported to the combustion furnace 17 through the gas-to-gas heat exchanger 15 for oxygen-assisted combustion. This process preheats the pyrolysis gas through the gas-to-gas heat exchanger 15 while cooling the 300°C inert gas output from the rotary pyrolysis furnace 5.

[0050] Fourth, the gas after the pyrolysis gas is burned is sent to the air mixing device 16 to generate sufficient drying gas after air distribution, and then the drying gas is introduced into the drying process to finally dry the biomass raw materials.

[0051] In this step, the high-temperature gas generated by combustion is also input into the air mixing device 16 to increase the supply of drying gas. The heat generated by combustion is used to mix with the lower-temperature inert gas to meet the supply of drying gas.

[0052] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the inventive concept and technical solution of the present invention, or the inventive concept and technical solution are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A system for producing biochar using cement kiln inert gas, comprising a feeding module, a pyrolysis gas processing module, and a biochar collection and storage module, characterized in that: It also includes a drying pyrolysis device and a cement kiln inert gas supply module, the pyrolysis gas outlet (510) of the drying pyrolysis device is connected to the pyrolysis gas processing module, and the solid product outlet (506) of the drying pyrolysis device is connected to the biomass charcoal storage module. The drying pyrolysis device includes a drying device (4), a screw conveying device and a rotary pyrolysis furnace (5). A spiral coil (511) is fixed to the inner wall of the rotary furnace body (502) of the rotary pyrolysis furnace (5). One end of the spiral coil (511) is connected to the cement kiln inert gas supply module to receive high-temperature inert gas, and the other end is cooled by a cooling structure and then passed into the drying device (4). The inlet of the drying device (4) receives the biomass raw material supplied by the feeding module. The outlet of the drying device (4) is sealed and connected to the inlet of the screw conveying device. The outlet of the screw conveying device is connected to the inner cavity of the rotary furnace body (502). The rotary pyrolysis furnace (5) further comprises a feed end cover (503) and a discharge end cover (504), wherein an annular protrusion (516) is provided on the inner side of each of the feed end cover (503) and the discharge end cover (504), wherein each of the annular protrusions (516) is rotatably sleeved with a corresponding rotating ring (515), wherein the rotating ring (515) is fixedly sleeved on both ends of the rotary furnace body (502), and an annular cavity is provided in the annular protrusion (516). The rotating ring (515) is provided with an annular cavity 2, the outer edge of the rotating ring (515) extends into the annular protrusion (516), the annular cavity 1 is communicated with the annular cavity 2, and a sealing structure is provided between the rotating ring (515) and the annular protrusion (516), the annular protrusion (516) is provided with an interface 1 for connecting to an external air pipe, and the rotating ring (515) is provided with an interface 2 for connecting to the spiral coil (511); A spiral conveying structure is provided in the rotary furnace body (502), and the spiral conveying structure includes a spiral heat-conducting blade (512). The outer edge of the spiral heat-conducting blade (512) is welded to the spiral coil (511), and the spiral heat-conducting blade (512) divides the inner cavity of the rotary furnace body (502) into a spiral cavity.

2. The system for producing biochar using cement kiln inert gas according to claim 1, characterized in that: A feed hole is provided at the center of the feed end cover (503), and the spiral conveying structure further comprises a transmission shaft (513) located at the center of the spiral heat-conducting blade (512), one end of the transmission shaft (513) passes through the feed hole and extends into the barrel (501) of the spiral conveying device, a spiral heat-insulating blade (514) is provided in the barrel (501), and the spiral heat-insulating blade (514) is fixed to the part of the transmission shaft (513) extending into the spiral conveying device, the outer edge of the spiral heat-insulating blade (514) is in contact with the barrel (501) and separates the inner cavity of the barrel (501) to form a spiral cavity, and the rotation direction of the spiral heat-insulating blade (514) is opposite to that of the spiral heat-conducting blade (512).

3. The system for producing biochar using cement kiln inert gas according to claim 2, characterized in that: The end face of the discharge end cover (504) is provided with a pyrolysis gas outlet (510), and the pyrolysis gas outlet (510) discharges pyrolysis gas outward. The end face of the annular protrusion (516) of the discharge end cover (504) is also provided with a ring sleeve (505) sleeved outside the cylinder (501), and the solid product outlet (506) is fixed below the ring sleeve (505). The side wall of the discharge end of the cylinder (501) is provided with a discharge groove (517) connected to the solid product outlet (506), and the discharge groove (517) and the ring sleeve (505) are sealed by a sealing member, and the sealing member is fixed on the outside of the discharge groove (517).

4. The system for producing biochar using cement kiln inert gas according to claim 3, characterized in that: A conveying mechanism (402) is provided in the housing (401) of the drying device (4), an inlet is provided on the upper side of the feed end of the housing (401) of the drying device (4), and an outlet is provided on the lower side of the discharge end of the housing (401). The upper part of the feed end of the housing (401) is connected to an outlet pipe 2 (404) for outputting drying gas, and the lower part of the discharge end of the housing (401) is connected to an inlet pipe 2 (403) for inputting drying gas. The drying gas is formed by cooling the high-temperature inert gas outputted from the rotary pyrolysis furnace (5) through a cooling module; the cooling module includes an air mixing device (16), the air inlet end of the air mixing device (16) is respectively connected to an outlet pipe 1 (508) and a blower (18) for inputting a lower-temperature inert gas, and the air outlet end of the air mixing device (16) is connected to the inlet pipe 2 (403).

5. The system for producing biochar using cement kiln inert gas according to claim 4, characterized in that: The pyrolysis gas treatment module includes a liquid separation cooler (8) connected to the pyrolysis gas outlet (510) and a combustible gas purification tower (10), a water seal tank (11), a gas cabinet (12) and a combustion furnace (17) connected in sequence from the gas outlet of the liquid separation cooler (8) through pipelines. The pyrolysis gas treatment module also includes an infusion pump (9) connected to the liquid outlet of the liquid separation cooler (8), and the combustion furnace (17) is connected to an oxygen distribution fan (19) for inputting oxygen.

6. The system for producing biochar using cement kiln inert gas according to claim 5, characterized in that: The exhaust port of the combustion furnace (17) is connected to the air inlet end of the air mixing device (16) through a pipeline, and the gas obtained after combustion is sent to the air mixing device (16) to supplement the inert gas; the cooling module also includes an air-to-air heat exchanger (15), and the gas cabinet (12) is connected to the combustion furnace (17) through an air supply pipeline, and the air outlet pipe (508) and the air supply pipeline both pass through the air-to-air heat exchanger (15).

7. The system for producing biochar using cement kiln inert gas according to claim 6, characterized in that: The cement kiln inert gas supply module includes a preheater (13), and the exhaust gas outlet of the preheater (13) is connected to the spiral coil (511) inside the rotary pyrolysis furnace (5) through an air intake duct and a high-temperature fan (14).

8. A method for producing biochar using cement kiln inert gas, characterized in that: The system for producing biochar using cement kiln inert gas according to claim 7 comprises the following steps:

1. The high-temperature inert gas generated by the preheater (13) is sequentially passed through the rotary pyrolysis furnace (5), the air mixing device (16), and the drying device (4) before being discharged; 2. Inputting biomass raw materials into the drying and pyrolysis device, and performing drying and pyrolysis reactions in sequence; 3. The biochar enters the biochar collection and storage module for storage, and the pyrolysis gas enters the pyrolysis gas treatment module for gas-liquid separation, purification and combustion treatment; Fourth, the gas after the pyrolysis gas combustion is sent to the air mixing device (16) to generate sufficient drying gas after air distribution, and then the drying gas is introduced into the drying device (4) to finally dry the biomass raw material; The high-temperature inert gas at 350°C is introduced into the spiral coil (511) to heat the rotary pyrolysis furnace (5). The temperature of the high-temperature inert gas output from the rotary pyrolysis furnace (5) is reduced to 300°C. The high-temperature inert gas is then controlled at 200°C after passing through the air mixing device (16) and air distribution to form drying gas. The drying gas is then introduced into the drying device (4) for drying.

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