Continuous discharging flame curtain pyrolysis kiln and biochar preparation method

Abstract

The invention relates to the field of resource utilization of agricultural and forestry waste biomass and biochar preparation. The invention provides a continuous discharging flame curtain pyrolysis kiln and a biochar preparation method. The pyrolysis kiln comprises a hollow pyrolysis kiln body, a feeding port is formed in the top of the pyrolysis kiln body, and a discharging port is formed in the bottom of the pyrolysis kiln body; the pyrolysis kiln further comprises a support and a discharging pipeline, and the pyrolysis kiln body is arranged on the support, so that the lower end of the pyrolysis kiln body is suspended; one end of the discharging pipeline is provided with a feeding port, the other end of the discharging pipeline is provided with a discharging port, and one end of the feeding port is arranged at the lower end of the discharging port and communicated with the discharging port. The method comprises the following steps: S1, continuously putting straws into a pyrolysis kiln body, igniting, and carrying out a pyrolysis reaction; s2, pyrolysis products enter a discharging pipeline from the bottom of the pyrolysis kiln body and are compressed and cooled in the discharging pipeline, and the prepared biochar is discharged from a discharging opening of the discharging pipeline. The production efficiency of the rice straw biochar is improved, effective cooling is promoted, and the biochar preparation quality is improved.

Description

Technical Field

[0001] The present application relates to the field of resource utilization of agricultural and forestry waste biomass and biochar preparation, and specifically, to a continuous discharge flame curtain pyrolysis kiln and a biochar preparation method. Background Art

[0002] The flame curtain pyrolysis kiln uses the oxygen-deficient environment formed by the combustion of the surface raw materials to pyrolyze the internal raw materials under oxygen-free conditions to produce biochar. This technology has a high efficiency in the carbonization of wood raw materials, but it still faces challenges in the large-scale application of lightweight rice straw.

[0003] The biochar produced by carbonizing rice straw, such as rice, upland rice, wheat, and barley, is light and porous, with a mass-to-volume ratio of less than 1 / 10 of that of wood raw materials, resulting in a low mass load of raw materials per unit volume. The carbonized products quickly fill the interior of the pyrolysis kiln, which needs to be emptied after each round of operation. Production is frequently interrupted, making it difficult to achieve continuous operation. In order to improve production efficiency, traditional solutions attempt to compress the straw before carbonization to increase the raw material load per unit volume. However, rice straw has a high fiber content and is prone to forming dense blocks after compression, which hinders the pyrolysis process, causes uneven carbonization, and causes fluctuations in the quality of biochar. At the same time, the heat storage effect of porous biochar slows down the efficiency of natural cooling and limits the turnover efficiency of the pyrolysis kiln. If water injection annealing is used to accelerate cooling, low-density biochar tends to float in water, cooling is uneven, and water absorption and agglomeration will cause the pore structure to collapse, which will lead to a decrease in the quality of biochar.

[0004] In summary, the existing devices and methods for preparing biochar have low production efficiency and the quality of the obtained biochar is poor. There is an urgent need for a device that can continuously prepare high-quality biochar from lightweight rice straw to achieve efficient and large-scale preparation of rice straw biochar. Summary of the invention

[0005] The purpose of the present invention is to provide a continuous discharging flame curtain pyrolysis kiln and a biochar preparation method to address the deficiencies in the above-mentioned prior art, so as to solve the problems of low rice straw production efficiency and poor quality of biochar produced in the prior art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: The present application provides a continuous discharge flame curtain pyrolysis kiln, which includes a hollow pyrolysis kiln body, a feeding port at the top of the pyrolysis kiln body, and a discharge port at the bottom of the pyrolysis kiln body. The pyrolysis kiln also includes a bracket and a discharge pipe, the pyrolysis kiln body is arranged on the bracket, so that the lower end of the pyrolysis kiln body is suspended; a feed port is arranged at one end of the discharge pipe, and a discharge port is arranged at the other end, and one end of the feed port is arranged at the lower end of the discharge port and is connected to the discharge port. The pyrolysis product enters the discharge pipe from the feed port, is compressed and cooled in the discharge pipe, and is discharged from the discharge port.

[0007] This application combines the pyrolysis kiln with the discharge pipe to achieve efficient pyrolysis and continuous discharge simultaneously, effectively solving the problem of low raw material mass load per unit volume and frequent emptying of the pyrolysis kiln after the carbonized products fill the kiln in the traditional method. The carbonized products directly enter the discharge pipe for compression treatment under the action of gravity, avoiding production interruption, thereby significantly improving production efficiency and realizing the continuous preparation of biochar.

[0008] This application adopts the method of discharging carbonized products from the bottom of the pyrolysis kiln, making full use of the temperature gradient characteristics inside the pyrolysis kiln, combining high-temperature pyrolysis with low-temperature discharge, so that the carbonized products experience a longer period of natural cooling before discharge, and are discharged from the lowest temperature position, thereby effectively reducing the upper temperature limit during discharge, and further improving the cooling effect. At the same time, the heat of the carbonized products of rice straw is mainly stored in the gaps between the carbon particles, rather than the carbon particles themselves. This application uses a discharge pipe to synchronously cool the carbonized products during the compression and transportation process, so that the heat inside the carbonized products can be discharged, accelerating the cooling, and avoiding the phenomenon of low-density carbon floating and pore collapse caused by traditional water injection annealing, thereby ensuring the structural integrity and quality stability of biochar. Compared with the traditional solution, this method not only improves the production efficiency of preparing biochar, but also improves the quality of biochar, making it more suitable for large-scale applications.

[0009] Furthermore, a screw and a spiral blade are arranged inside the discharge pipe, the discharge pipe supports the screw to rotate around its central axis, and the spiral blade is fixedly arranged on the screw. The screw and the spiral blade rotate around the central axis of the discharge pipe, so that the carbonized product can be pushed stably and continuously in the discharge pipe to avoid accumulation and ensure uniform discharge of the material. The spiral blade can exert an extrusion effect on the carbonized product during the transportation process to increase the density of the biochar.

[0010] Furthermore, the screw rod penetrates the discharge pipe. This design can effectively enhance the stability of the internal conveying structure of the discharge pipe by having the screw rod penetrate the discharge pipe and form a rotation support connection with the discharge pipe. At the same time, the screw rod is longer, which is convenient for providing rotational power support for the screw rod at both ends.

[0011] Furthermore, the thread pitch of the spiral blade gradually decreases from the feed port to the discharge port. The gradually decreasing thread pitch is to better compress the pyrolysis carbonization products. Through the gradient compression design, the density of the carbon block is increased from the initial loose state to 2-3 times the final state, significantly reducing the debris rate, and the carbon block is more regularly formed.

[0012] Furthermore, a heat sink is provided on the outer wall of the discharge pipe, which can increase the heat dissipation area of ​​the discharge pipe, enhance the heat exchange efficiency, and enable the carbonization product to cool down more quickly during the transportation process.

[0013] Furthermore, the size of the discharge port is larger than that of the feed port. The large size of the discharge port facilitates the discharge of the carbonized product and reduces product accumulation; the small size of the feed port facilitates the control of the feed amount and makes the carbonized product in the discharge pipe uniformly compressed.

[0014] Furthermore, the pyrolysis kiln body comprises a side wall and a bottom wall, and the discharge port is arranged in the middle of the bottom wall. The discharge port in the middle of the bottom wall can facilitate the discharge of materials.

[0015] Furthermore, the angle between the side wall and the bottom wall is 105°-115°. This inclination angle enables the carbonized product to slide smoothly to the bottom of the pyrolysis kiln, reduces the sliding resistance of the carbonized product, and effectively avoids the pyrolysis dead corner caused by accumulation in the horizontal section.

[0016] Furthermore, air inlet holes are provided on the side wall. The combustion surface is controlled within a specified range through the design of the air inlet holes, forming a stable flame curtain, so that the straw is fully pyrolyzed under smokeless combustion conditions.

[0017] The present application also proposes a method for preparing biochar, which comprises the following steps: S1. Continuously put the straw into the pyrolysis kiln and ignite it to carry out pyrolysis reaction; S2, the carbonized product generated by pyrolysis enters the discharge pipe from the bottom of the pyrolysis kiln body, is compressed and cooled in the discharge pipe, and the prepared biochar is discharged from the discharge port of the discharge pipe; The method is implemented using the above-mentioned pyrolysis kiln.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) In the present application, the pyrolysis kiln is connected to the discharge pipe, and the products after pyrolysis are completed enter the discharge pipe from the discharge port at the bottom of the pyrolysis kiln, where they are compressed and dissipated, and finally high-quality biochar is generated and discharged from the discharge port. The carbonized products will not quickly fill up the interior of the pyrolysis kiln, and there is no need to empty it after each round of operation, which avoids production interruptions and improves the discharge efficiency of the carbonized products. It is only necessary to continuously feed biomass raw materials into the feed port to obtain biochar from the discharge port. Therefore, the pyrolysis kiln of the present application can achieve stable and efficient continuous production of biochar. Compared with the traditional intermittent pyrolysis process, it improves production efficiency and avoids the problem of biochar quality degradation caused by water quenching.

[0019] (2) This application adopts a biochar preparation method of pyrolysis followed by compression, which allows the pyrolysis reaction to proceed without interference, avoiding the problem of pyrolysis obstruction caused by material densification in the traditional method. The gas and water produced by pyrolysis can be discharged smoothly, thereby ensuring uniform carbonization and improving the quality of biochar. Subsequently, the carbonized product is compressed in the discharge pipe, ensuring the structural stability of the biochar, avoiding the problem of pore collapse caused by compression first, and making the quality of the biochar finally prepared more stable and reliable.

[0020] (3) In the biochar preparation process of the present application, the carbonized product is discharged from the bottom of the pyrolysis kiln and the temperature in the discharge pipe gradually decreases during the transportation process, thereby achieving uniform heat release. This method avoids excessive carbonization of the biochar due to excessive local temperature, thereby affecting the carbonization quality; it also effectively reduces the internal stress concentration caused by sudden cooling, allowing the carbon particles to maintain the integrity of the pore structure during the shrinkage and shaping process, thereby improving the quality of the final biochar.

[0021] (4) The compression process and heat dissipation process in the discharge pipeline of this application work together to form a virtuous cycle. During the transportation process, the compression force causes the carbon particles to naturally arrange to form small holes, and the heat is dissipated from the pores; the continuous heat dissipation causes the compressed carbon to harden and shape during the gradual cooling process, maintaining a stable shape and preventing local agglomeration of the carbon. In the end, a high-quality product with good air permeability and stable texture is obtained, further improving the quality of biochar. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a continuous discharging flame curtain pyrolysis kiln provided by the present invention; Figure 2 A schematic diagram of a heat sink of a continuous discharging flame curtain pyrolysis kiln provided by the present invention.

[0023] Icons: 1-pyrolysis kiln body; 11-discharge port; 2-discharge pipe; 21-feed port; 22-discharge port; 3-screw; 4-spiral blade; 5-heat sink; 6-air inlet; 7-motor; 8-controller; 9-rocker arm; 10-pressure relief pipe. DETAILED DESCRIPTION

[0024] In order to make the implementation process of the present invention clearer, it will be described in detail below with reference to the accompanying drawings.

[0025] Embodiment 1: The present invention provides a continuous discharge flame curtain pyrolysis kiln, such as Figure 1As shown (the bracket is not shown in the figure), the pyrolysis kiln includes a hollow pyrolysis kiln body 1, a feeding port is provided at the top of the pyrolysis kiln body 1, and a discharge port 11 is provided at the bottom of the pyrolysis kiln body 1. The pyrolysis kiln also includes a bracket and a discharge pipe 2, the pyrolysis kiln body 1 is arranged on the bracket, so that the lower end of the pyrolysis kiln body 1 is suspended; a feed port 21 is provided at one end of the discharge pipe 2, and a discharge port 22 is provided at the other end, and one end of the feed port 21 is arranged at the lower end of the discharge port 11 and communicated with the discharge port 11. The pyrolysis product enters the discharge pipe 2 from the feed port 21, is compressed and cooled in the discharge pipe 2, and is discharged from the discharge port 22.

[0026] The pyrolysis kiln combines the pyrolysis kiln body 1 with the discharge pipe 2, realizing the simultaneous high-efficiency pyrolysis and continuous discharge, and improving the equipment utilization rate. Specifically, after the carbonized product generated by the pyrolysis of the straw enters the discharge pipe 2, it is compressed inside the discharge pipe 2 to make it tight during the transportation process, thereby improving the production continuity and avoiding production interruption. Experiments show that in a pyrolysis environment above 550°C, when the carbonized product fills three-quarters of the inside of the pyrolysis kiln body 1, the temperature at the bottom of the pyrolysis kiln body 1 can drop to about 40°C. It can be seen that the temperature at the bottom of the pyrolysis kiln body 1 is much lower than the pyrolysis zone, forming a significant temperature gradient. The method of discharging the carbonized product from the discharge port 11 at the bottom of the pyrolysis kiln body 1 utilizes the temperature gradient characteristics to obtain the lowest temperature upper limit and improve the cooling efficiency. Compared with the traditional top or side discharge method, it can effectively reduce the temperature of the carbonized product when discharging, improve the overall cooling efficiency, and enhance the safety and stability of production. At the same time, the heat of the rice straw carbonized product is mainly stored in the gaps between the carbon particles, rather than in the carbon particles themselves, and the internal heat of the carbonized product can be discharged through compression and natural convection heat dissipation of the discharge pipe 2. This cooling method reduces energy consumption, shortens cooling time, and improves the quality of rice straw biochar.

[0027] The pyrolysis kiln body 1 is made of metal material, which can be carbon steel, cast iron, stainless steel, etc., preferably iron. Iron has excellent high temperature resistance and structural strength, can operate stably under high temperature environment, and ensure safety and durability during pyrolysis. The material of the discharge pipe 2 can be carbon steel, stainless steel, alloy steel, aluminum alloy, wear-resistant alloy, etc., preferably, a special aluminum alloy material is used. Aluminum alloy material has light weight, high strength and good heat dissipation performance, which can effectively reduce the heat load of the equipment and maintain stable performance under high temperature environment, thereby preventing overheating and improving the working efficiency of the equipment. In addition, the bracket supporting the pyrolysis kiln body 1 is composed of three support arms, which are distributed at an angle of 120° to each other to form a triangular support surface to provide stable support. The bracket adopts a welded structure or a cast structure, and the material of the bracket can be steel, aluminum alloy or other high-strength metal materials. The shape and structure of the bracket are not specifically limited, and it is sufficient to support the pyrolysis kiln body 1.

[0028] The two ends of the discharge pipe 2 are respectively provided with a feed port 21 and a discharge port 22, wherein the feed port 21 is located on the upper side of one end of the discharge pipe 2 close to the pyrolysis kiln body 1, and the discharge port 22 is located on the lower side of the other end of the discharge pipe 2. Thus, a carbonization product processing path is formed, which enters from the upper feed port 21, is compressed and cooled in the discharge pipe 2, and then discharged from the lower discharge port 22 at the other end. The shape of the pipe body of the discharge pipe 2 can be cylindrical, which has a simple structure, is easy to process, and is suitable for stable discharge; it can also be a tapered cone, that is, the diameter of the pipe body of the discharge pipe 2 on the side of the discharge port 22 is smaller than the diameter on the side of the feed port 21. This shape helps to further compress the carbonization product and improve the discharge efficiency and cooling effect.

[0029] A screw 3 and a spiral blade 4 are arranged inside the discharge pipe 2. The discharge pipe 2 supports the screw 3. The screw 3 rotates around the central axis of the discharge pipe 2. The screw 3 coincides with the central axis of the discharge pipe 2, and the screw 3 passes through both ends of the discharge pipe 2. At the connection between the screw 3 and the two ends of the discharge pipe 2, bearings or high-temperature resistant sliding components are installed to support and rotate the screw 3, so that the screw 3 cannot move axially and can only rotate around the central axis. In this way, the screw 3 can rotate stably, ensure the continuity of the transportation of the carbonized product, and avoid the deviation of the screw 3 due to gravity or material accumulation. At the same time, it can also reduce the resistance during the transportation of the carbonized product, and avoid the blockage or damage of the carbonized product caused by pipeline vibration or friction during the transportation process. A spiral blade 4 is fixedly arranged on the screw 3, and the spiral blade 4 is located inside the discharge pipe 2. There is a gap between the spiral blade 4 and the inner wall of the discharge pipe 2, and the gap range is 2-5mm. During the conveying process, the spiral blade 4 guides the movement path of the carbonized product to avoid accumulation and ensure uniform discharge of the product; at the same time, it exerts a certain squeezing effect on the carbonized product, so that it is gradually compacted during movement and the density is increased. In addition, the rotating conveying method of the spiral blade 4 can increase the contact area between the carbonized product and the pipe wall and enhance the cooling efficiency. The spiral blade 4 is fixed to the screw 3 by welding, and an integrated spiral conveying structure of the screw 3 and the spiral blade 4 can also be produced by an integrated molding process.

[0030] The thread pitch of the spiral blade 4 gradually decreases from the end of the feed port 21 to the end of the discharge port 22. When the spiral blade 4 is distributed along the axial direction of the screw 3, a tapered pitch design is adopted, that is, the pitch of the spiral blade 4 is larger at the end close to the feed port 21, and the pitch gradually decreases at the end close to the discharge port 22. Near the end of the feed port 21, the thread pitch is 100-150mm. After the carbonized product enters the discharge pipe 2, the larger pitch of the spiral blade 4 provides a larger conveying space, reducing the risk of accumulation and blockage at the feed port 21. As the carbonized product advances along the pipeline, the pitch of the spiral blade 4 gradually decreases, and the pitch range is 80-100mm, which slightly reduces the flow speed of the carbonized product and gradually forms a compaction trend; at the same time, through the change of pitch, the compression effect also allows heat to be conducted through the side wall of the discharge pipe 2 for cooling. Near the discharge port 22, the pitch of the spiral blade 4 is the smallest, and the pitch range is 40-80mm, forming a compression effect and increasing the density of the carbonized product. In practice, the thread pitch of the spiral blade 4 may be optimized and dynamically adjusted according to the physical properties, conveying rate and compression requirements of the biochar. The design of gradually decreasing the thread pitch of the spiral blade 4 enables the carbonized product to enter quickly, be conveyed smoothly, be gradually compacted and be discharged evenly during the conveying process, thereby achieving efficient and stable material conveying, while optimizing cooling and finished product quality, and providing more reliable technical support for large-scale biochar production.

[0031] A pressure relief pipe 10 is provided on the wall of the discharge pipe 2, which is a uniformly distributed tubular structure, and the inner diameter of the pressure relief pipe 10 ranges from 0.1 to 2 mm to ensure the effect of pressure relief and heat removal. During the cooling and molding process of the pyrolysis product, if the residual gas inside cannot be discharged in time, the carbon structure will become loose or the pores will collapse, affecting the density of the final product. The setting of the pressure relief pipe 10 can provide an exhaust channel, so that the gas and heat can be released smoothly and the internal pressure accumulation can be reduced. Some carbon slag will adhere to the inner wall of the pressure relief pipe 10, which helps to maintain the stability of the carbon molding environment, and the carbon slag will be discharged from the pipe due to air pressure when exhausting, and will not cause blockage. Among them, the smaller inner diameter of 0.1-0.5 mm is suitable for high-density carbon materials, which can effectively prevent material loss and ensure molding quality; the larger inner diameter of 1-2 mm is suitable for carbon materials with higher porosity, which helps to discharge gas faster and reduce the risk of pore collapse. In terms of structural layout, the length of the pressure relief pipe 10 ranges from 0.5 to 2 cm to avoid excessive material loss while maintaining appropriate pressure relief and exhaust effects. The pressure relief pipe 10 is longer on the side close to the feed port 21, with a length range of 1.4-2 cm, so that more gas and heat can be released at the beginning of the pyrolysis product entering the cooling area to prevent excessive accumulation of volatiles inside and affect the densification of the carbon. The side close to the discharge port 22 is shorter, with a length range of 0.5-0.8 cm, which is mainly used for trace gas and heat emissions in the final stage to ensure that the biochar has reached the expected molding quality before discharge. In addition, the pressure relief pipe 10 is made of metal, which has good thermal conductivity, helps the conduction and diffusion of heat, and makes the cooling of the carbonized product more uniform. The metal material also ensures the structural strength and durability of the pressure relief pipe 10, so that it can operate stably under long-term high temperature conditions. This design not only optimizes the density and uniformity of biochar, but also improves the stability of the entire cooling and discharge process, thereby improving the density and quality of biochar.

[0032] Heat sinks 5 are provided on the outer wall of the discharge pipe 2. A plurality of heat sinks 5 are distributed radially and fixed to the outer wall surface by welding or bolts. The heat sink 5 can increase the heat dissipation area of ​​the discharge pipe 2, reduce the heat storage effect of the carbonized product, and quickly cool down the carbonized product during transportation, thereby avoiding local overheating and causing a decrease in the quality of the biochar. The surface design of the heat sink 5 adopts a non-smooth structure, the purpose of which is to increase the contact area with the air by increasing the surface roughness, thereby enhancing the heat exchange efficiency. This rough surface can also adopt a fin-like structure or a wavy structure to increase the surface area, improve the overall performance of the heat sink 5, and promote faster heat dissipation of the carbonized product. Compared with a smooth wall surface, this design can increase the heat exchange area by 2-3 times, so that the carbonized product can be better hardened and shaped during compression, thereby improving the quality of the generated biochar. The shape of the heat sink 5 can also adopt an annular sheet structure, such as Figure 2As shown, the heat sink 5 surrounds the outer wall of the discharge pipe 2 and is connected to the pressure relief pipe 10, which can effectively increase the heat dissipation area, evenly distribute heat, improve heat dissipation efficiency, and promote rapid cooling of the carbonized product. Specifically, the length of the heat sink 5 is 50-150mm, the thickness is 2-10mm, and the spacing between the heat sinks 5 is 10-30mm. At one end near the pyrolysis kiln body 1, due to the high temperature, in order to further improve the heat dissipation efficiency, the spacing between the heat sinks 5 can be 10-15mm, and the length can be 100-150mm, so as to better and quickly dissipate heat; a blowing device can also be set to force air flow to further improve the heat dissipation effect. The material of the heat sink 5 is selected from materials with excellent thermal conductivity, high temperature resistance, and corrosion resistance, such as aluminum alloy, copper, stainless steel, magnesium alloy or titanium alloy, to ensure long-term stable operation. The heat sink 5 achieves heat diffusion and dissipation by increasing the surface area of ​​the outer wall and air convection, and conducts heat from the discharge pipe 2 to the external environment. The cooling efficiency is high, and the cooling effect can be distributed more evenly to avoid overheating in a certain area. This design allows the carbonized product to be cooled quickly without long annealing or additional large amounts of water quenching, achieving efficient cooling and ensuring that the cooled biochar can be discharged smoothly.

[0033] The size of the discharge port 11 of the pyrolysis kiln body 1 is larger than the size of the feed port 21 of the discharge pipe 2. The shapes of the above-mentioned discharge port 11, feed port 21 and discharge port 22 can be various, preferably circular, so as to facilitate the passage of materials. The diameter of the discharge port 11 is larger than the feed port 21, forming a conical transition structure, so that the carbonized product has enough space to flow when entering the discharge pipe 2, and will not accumulate or be blocked due to the small channel before the carbonized product is discharged, thereby ensuring continuous discharge. Specifically, the size of the discharge port 11 is 1-1.5 times the size of the feed port 21. This design can ensure that the carbonized product is discharged from the pyrolysis kiln body 1 and smoothly enters the discharge pipe 2, reducing the accumulation of carbonized products and facilitating the control of the feed amount. A pipe is used between the discharge port 11 and the feed port 21 to connect them, and the two ends of the pipe are connected to the discharge port 11 and the feed port 21 by flanges and fixed by bolts. If necessary, a sealing gasket can be added to prevent leakage. This connection method ensures a stable structure and enhances the durability of the equipment; at the same time, it is easy to disassemble and maintain, improving the operability of the equipment.

[0034] In order to further optimize the smoothness of the discharge process, a vibration device is also provided at the pipe connection, which includes an eccentric wheel and a connecting rod. The eccentric wheel is installed at the end of the screw 3 near the feed port 21, and is connected to the screw 3 through a bearing to ensure that the eccentric wheel can rotate with the rotation of the screw 3. The eccentricity range of the eccentric wheel is set between 2-10mm, and the specific value can be adjusted according to actual needs to control the amplitude of the vibration. One end of the connecting rod is fixed to the eccentric wheel, and the other end is fixed to the outside of the pipe connection. When the screw 3 rotates, the centrifugal force of the eccentric wheel is transmitted to the pipe connection through the connecting rod, causing the pipe connection to vibrate periodically. This vibration can effectively reduce the accumulation and blockage of carbonization products at the pipe connection, ensuring the continuity and stability of the discharge process. At the same time, installing elastic supports such as spring washers and rubber gaskets at the flange connection between the feed port 21 and the pipe connection can enhance the response of the pipe connection to the vibration of the screw 3, thereby effectively amplifying the vibration amplitude and further promoting smooth discharge. The pipe and flange can be made of high temperature resistant materials such as stainless steel and high temperature alloy, and the sealing gasket can be made of metal gasket, graphite gasket and ceramic gasket to ensure the sealing performance. The eccentric wheel and connecting rod can be made of high strength wear-resistant alloy to ensure long-term stable operation in high temperature and vibration environment.

[0035] Furthermore, in order to achieve efficient driving and stable control of the discharge pipe 2, two power systems, an electric drive and a manual drive, are respectively arranged at both ends of the screw 3. The length of the screw 3 is greater than the axial length of the discharge pipe 2, and the screw 3 runs through the discharge pipe 2. Among them, the electric drive system is arranged at one end close to the feed port 21, and the manual drive system is arranged at one end close to the discharge port 22. At the end of the screw 3 close to the feed port 21, a motor 7 is arranged, and the motor 7 is located on the lower side of the discharge pipe 2, and the motor shaft is parallel to the screw 3. The motor 7 provides power for the screw 3 to drive the rotation of the screw 3, and the motor shaft is connected to the screw 3 by a belt. The belt drive system is adapted to high temperature environments, has high transmission efficiency and low noise, and this connection method can reduce mechanical wear and extend the service life of the system. A controller 8 is also provided, and the controller 8 is electrically connected to the motor 7. The controller 8 adjusts the working parameters of the motor 7, such as the rotation speed, by adjusting the output power. The greater the output power, the higher the rotation speed, and the smaller the output power, the lower the rotation speed, thereby controlling the discharge rate of the discharge port 22, adapting to different material characteristics and transportation requirements, and ensuring the stability and controllability of the transportation process. A rocker arm 9 is provided at one end of the screw 3 near the discharge port 22. The rocker arm 9 provides power to the screw 3 by manual drive to ensure that the transportation process of the carbonized product is not interrupted. A ball bearing connection is provided between the rocker arm 9 and the screw 3. This connection method reduces the resistance of the rocker arm 9 to the rotational movement of the screw 3, improves the transmission efficiency, and at the same time reduces wear and extends the service life.

[0036] In order to achieve isolation between electric drive and manual drive, live flywheels are also provided at both ends of the screw 3. A first live flywheel is provided between the screw 3 and the belt, and a second live flywheel is provided between the screw 3 and the ball bearing. The live flywheel is a mechanical component that can provide rapid decoupling between electric drive and manual drive, and can reduce the impact and interference when switching between different drive modes. The live flywheel ensures that the motor 7 will not drive the rocker arm 9 to rotate when it is running, and manual intervention in the rocker arm 9 will not affect the operation of the motor 7. Through the buffering effect of the live flywheel, the operations of the motor 7 and the rocker arm 9 do not interfere with each other, which not only improves the convenience of operation, but also provides reliable guarantee for manual intervention in emergency situations, and improves the adaptability of the discharge pipe 2 under different working conditions, so that it can operate stably in various environments.

[0037] Furthermore, the pyrolysis kiln body 1 includes a side wall and a bottom wall, and the discharge port 11 is arranged in the middle of the bottom wall, so as to avoid the problem that the carbonized product flows unevenly or is difficult to discharge due to the offset discharge port 11. The side wall of the pyrolysis kiln body 1 is designed with an inclination angle, specifically, the angle between the side wall and the bottom wall is 105º-115º. This angle optimizes the sliding path of the carbonized product, so that it can slide smoothly to the bottom of the pyrolysis kiln body 1, reduce the resistance during the sliding process, and reduce the retention and accumulation of the carbonized product. If the angle is too small, the product slides too fast, and the pyrolysis may not be complete, affecting the quality of the generated biochar; if the angle is too large, the carbonized product may be retained on the side wall, increasing the sliding resistance, causing the carbon layer to break, thereby affecting the integrity of the biochar. The selection of the angle range of 105º-115º can effectively balance the sliding speed and pyrolysis uniformity, and improve the pyrolysis efficiency.

[0038] In order to optimize the combustion process, an air inlet 6 is also provided on the side wall of the pyrolysis kiln body 1, and the air inlet 6 is distributed circumferentially along the top edge of the pyrolysis kiln body 1. The design of the air inlet 6 helps to control the height and combustion intensity of the combustion surface, thereby maintaining the stability of the flame curtain and allowing the straw to be fully pyrolyzed under smokeless combustion conditions. Specifically, the position of the air inlet 6 is 10-15 cm away from the top edge of the pyrolysis kiln body 1. The position selection in this range helps to optimize the air inflow path, so that the incoming air is evenly distributed to the combustion area to form a stable flame curtain. The aperture range of the air inlet 6 is 5-20 mm, which can be adjusted according to the pyrolysis kiln bodies 1 of different sizes to ensure sufficient air flow. In this way, it can ensure that the flame curtain covers the entire top surface of the pyrolysis kiln body 1 and achieve efficient and smokeless combustion, and avoid excessive air supply causing temperature drop, resulting in unstable pyrolysis environment, or insufficient air supply causing uneven combustion. When the straw is ignited, air enters the combustion area through the air inlet 6, which helps to maintain the stability of the flame curtain, ensure uniform combustion, improve pyrolysis efficiency, and optimize the overall energy efficiency of the equipment.

[0039] In actual application, the pyrolysis kiln body 1 is arranged on a bracket, which provides a stable support for the pyrolysis kiln body 1, so that the bottom end of the pyrolysis kiln body 1 is suspended in the air, and the safety and stability of the pyrolysis kiln body 1 during operation are ensured. When in use, the pyrolysis kiln body 1 is filled with dried light rice straw, such as rice, wheat, barley and other straws, until the filler is close to the position below the air inlet 6. When the straw raw material is filled to this position, the straw is ignited, and the raw material is continued to be filled while burning to ensure that the combustion surface is always kept within a specific range. In this way, a stable flame curtain can be continuously formed to promote the smooth start of the pyrolysis reaction. In this process, the stability of the flame curtain ensures the uniformity and efficiency of the pyrolysis process and improves the pyrolysis efficiency.

[0040] As the pyrolysis reaction of the straw in the pyrolysis kiln body 1 proceeds, the carbonized product falls into the discharge pipe 2 from the discharge port 11 at the bottom of the pyrolysis kiln body 1 under the action of gravity. After the carbonized product enters the discharge pipe 2, the motor 7 is started by the controller 8, and the power of the motor 7 is transmitted to the screw 3 through the belt, driving the spiral blade 4 to rotate, thereby pushing the carbonized product to move toward the discharge port 22. As the thread pitch of the spiral blade 4 gradually decreases, the carbonized product is not only pushed forward, but also gradually compressed during the movement, and the density continues to increase, forming a more compact block. At the same time, the heat sink 5 on the outer wall of the discharge pipe 2 increases the contact area of ​​the air, effectively promotes the natural convection heat dissipation of the carbonized product, thereby reducing the temperature of the carbonized product, preventing excessive heat accumulation during the transportation process, and improving the quality of biochar preparation. Finally, after compression and cooling of the discharge pipe 2, the carbonized product is smoothly discharged through the discharge port 22 to form high-density and high-quality biochar. The whole process not only improves the continuity of biochar preparation, but also improves the density and quality of biochar.

[0041] In general, the pyrolysis kiln generates biochar by first making carbon and then compressing it, and cooling it while compressing. This solves the problems of poor continuity and low production quality of lightweight rice straw in the existing technology, and is suitable for improving the production efficiency and cooling effect of rice straw biochar.

[0042] Embodiment 2: Based on the pyrolysis kiln in Example 1, the present application also proposes a method for preparing biochar, which comprises the following steps: S1, continuously put straw into the pyrolysis kiln body 1, and ignite it to carry out pyrolysis reaction; the straw is a light rice straw, such as rice, upland rice, wheat and highland barley straw. To ensure the stable progress of the pyrolysis reaction, the straw can be pre-treated as needed, such as drying and cutting, to improve the combustion efficiency. The straw raw material is continuously put into the pyrolysis kiln body 1 for combustion. The heat released during the combustion process maintains the high temperature environment in the pyrolysis kiln body 1 to ensure the smooth progress of the pyrolysis reaction. During the pyrolysis process, the straw raw material decomposes at high temperature to generate volatile gases and solid carbonized products, and the flame curtain generated by the combustion effectively provides the required heat energy to promote the continuous pyrolysis reaction. By controlling the straw combustion surface to be maintained within the range of 20-30cm below the air inlet 6, the stability of the flame curtain is ensured, and the excessive straw raw material input is prevented from affecting the inflow of air, thereby ensuring the uniformity of the pyrolysis process.

[0043] S2, the carbonized product generated by pyrolysis enters the discharge pipe 2 from the bottom of the pyrolysis kiln body 1, is compressed and cooled in the discharge pipe 2, and the prepared biochar is discharged from the discharge port 22 of the discharge pipe 2; the carbonized product generated by the pyrolysis reaction enters the discharge pipe 2 from the bottom of the pyrolysis kiln body 1 by gravity, and the pyrolysis carbonized product with the lowest temperature is obtained. At this time, the belt connection between the motor 7 and the screw 3 drives the spiral blade 4 to start rotating, pushing the carbonized product to move along the discharge pipe 2 toward the discharge port 22. In this process, the rotation of the spiral blade 4 not only pushes the carbonized product forward, but also gradually compresses the carbonized product through its structure, so that the density of the carbonized product continues to increase. At the same time, the heat sink 5 on the discharge pipe 2 and its outer wall promotes the natural convection heat dissipation of the carbonized product by increasing the contact area with the air, effectively reduces the temperature of the carbonized product, and avoids the occurrence of overheating, thereby ensuring the production quality of biochar. Finally, under the effects of cooling and compression, the biochar with uniform quality and high density is discharged smoothly from the discharge port 22, completing the entire discharge process. In order to ensure the continuous production of biochar, the controller 8 adjusts the speed of the motor 7 so that the discharge rate of the discharge pipe 2 matches the straw feeding rate, ensuring that the straw combustion surface remains within the height range set in step S1. This adjustment mechanism can ensure the stability of the pyrolysis process, keep the biochar production process balanced and continuous, avoid fluctuations in pyrolysis efficiency due to unstable combustion surfaces, and effectively improve the production efficiency and quality of biochar.

[0044] The method of the present application is implemented using the pyrolysis kiln of Example 1, thereby achieving continuous preparation of straw biochar.

[0045] In actual operation, straw is continuously put into the pyrolysis kiln body 1 for combustion to provide heat and induce pyrolysis reaction. When the straw is filled to the combustion surface close to the air inlet 6, in order to prevent the screw 3 from suddenly running at high speed and causing uneven quality of discharged biochar, the power of the controller 8 needs to be adjusted to "0" first, and then the controller 8 switch is turned on, and the power is slowly adjusted to make the spiral blade 4 rotate smoothly, and the carbonized product is pushed to move to the discharge port 22 for compression and cooling. At the same time, due to the movement of the carbonized product, the straw layer in the pyrolysis kiln body 1 gradually decreases, so that the combustion surface falls back to the range of 20-30cm below the air inlet 6. In order to ensure the stability of the pyrolysis process, it is necessary to adjust the power of the controller 8 so that the discharge rate matches the straw feeding rate. For example, when the output power of the controller 8 is adjusted to the 1 / 2 position of the maximum power, the discharge rate and the feeding rate reach a balance, ensuring the continuity of the straw combustion process, and maintaining the height of the combustion surface within the setting range of step S1. After compression and cooling of the discharge pipe 2, the discharge port 22 will continuously discharge high-quality and uniformly dense biochar. In this way, the pyrolysis process can be ensured to proceed stably, the biomass raw materials can be heated evenly, and stable and continuous biochar emissions can be achieved, thereby improving the quality and production efficiency of biochar.

[0046] Furthermore, the discharge rate of the discharge port 22 can also be controlled by manually rotating the rocker arm 9. In actual operation, first, the straw raw material is continuously fed into the pyrolysis kiln body 1 for combustion to start the pyrolysis reaction. When the straw is filled to the point where the combustion surface is close to the air inlet 6, the feeding is stopped, and the rocker arm 9 is manually rotated to drive the screw 3 to rotate, thereby driving the spiral blade 4 to rotate. The carbonized product moves from the bottom end of the pyrolysis kiln body 1 into the discharge pipe 2, and the filling surface drops accordingly. When the combustion surface drops to a predetermined height, the feeding is resumed to maintain the continuous pyrolysis process until the straw combustion surface is close to the air inlet 6 again, and the above steps are repeated. In this way, when the electric mode is limited, semi-continuous processing of straw can still be achieved to ensure the stable discharge of biochar, thereby enhancing the adaptability and reliability of the device under various working conditions.

[0047] The pyrolysis kiln device and method of the present application can also be integrated into a harvester or agricultural vehicle to achieve on-site pyrolysis of straw and direct return to the field for utilization. For example, a continuous discharge flame curtain pyrolysis kiln can be integrated with a rice harvester. During the harvesting process, the rice is processed by the harvester and stored in the rice bin, while the rice straw directly enters the pyrolysis kiln body 1 to undergo a pyrolysis reaction under high temperature. The generated rice straw carbonization product is compressed and cooled in the discharge pipe 2, and the straw biochar is discharged from the discharge port 22 to the field. Subsequently, the rotary tiller can further mix the biochar into the soil to increase the soil organic matter content and improve the soil aggregate structure. The pyrolysis kiln device reduces transportation and storage costs, reduces incineration emissions, and improves soil fertility through on-site pyrolysis. At the same time, the device is suitable for different operating environments and can be integrated into a variety of agricultural machinery to improve equipment utilization and agricultural production efficiency.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous discharging flame curtain pyrolysis kiln, the pyrolysis kiln comprising a hollow pyrolysis kiln body, the top of the pyrolysis kiln body having a feeding port, characterized in that: A discharge port is provided at the bottom of the pyrolysis kiln body. The pyrolysis kiln also includes a bracket and a discharge pipe. The pyrolysis kiln body is arranged on the bracket so that the lower end of the pyrolysis kiln body is suspended. A feed port is provided at one end of the discharge pipe, and a discharge port is provided at the other end. One end of the feed port is provided at the lower end of the discharge port and is connected with the discharge port. The pyrolysis product enters the discharge pipe from the feed port, is compressed and cooled in the discharge pipe, and is discharged from the discharge port.

2. The continuous discharge flame curtain pyrolysis kiln according to claim 1, characterized in that: A screw and a spiral sheet are arranged inside the discharge pipe. The discharge pipe supports the screw to rotate around its central axis, and the spiral sheet is fixedly arranged on the screw.

3. The continuous discharge flame curtain pyrolysis kiln according to claim 2, characterized in that: The screw rod passes through the discharge pipe.

4. The continuous discharge flame curtain pyrolysis kiln according to claim 3, characterized in that: The thread pitch of the spiral sheet gradually decreases from one end of the feed inlet to one end of the discharge outlet.

5. The continuous discharge flame curtain pyrolysis kiln according to claim 4, characterized in that: The outer side wall of the discharge pipe is provided with a heat sink.

6. The continuous discharge flame curtain pyrolysis kiln according to claim 5, characterized in that: The size of the discharge port is greater than the size of the feed port.

7. The continuous discharge flame curtain pyrolysis kiln according to claim 6, characterized in that: The pyrolysis kiln body comprises a side wall and a bottom wall, and the discharge port is arranged in the middle of the bottom wall.

8. The continuous discharge flame curtain pyrolysis kiln according to claim 7, characterized in that: The included angle between the side wall and the bottom wall is 105°-115°.

9. The continuous discharge flame curtain pyrolysis kiln according to claim 8, characterized in that: The side wall is provided with an air inlet.

10. A method for preparing biochar, characterized in that: The method comprises the following steps: S1. Continuously put the straw into the pyrolysis kiln and ignite it to carry out pyrolysis reaction; S2, the carbonized product generated by pyrolysis enters the discharge pipe from the bottom of the pyrolysis kiln body, is compressed and cooled in the discharge pipe, and the prepared biochar is discharged from the discharge port of the discharge pipe; The method is implemented using the pyrolysis kiln described in any one of claims 1-9.

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