A continuous pyrolysis biochar production containment system and method

Abstract

The present application relates to the technical field of biomass thermo-chemical conversion and carbon removal, and particularly relates to a continuous pyrolysis biochar production sealing system and method, which comprises a feeding assembly, a pyrolysis main furnace and a discharging assembly; a feeding screw in the feeding assembly is provided with a variable-pitch compression structure to form a mechanical bolt seal section in a feeding cylinder; a discharging cylinder in the discharging assembly is upwardly inclined and cooperates with a discharging screw to form a granular carbon seal section in the discharging cylinder; the sum of effective lengths of the mechanical bolt seal section and the granular carbon seal section is not less than an effective stroke length of an internal reaction zone of the pyrolysis main furnace; the discharging assembly can further comprise a jacketed cylinder structure, a hollow screw shaft, a cooling liquid conveying device and a rotary joint to continuously cool the high-temperature biochar. The present application can improve the sealing capacity and operation stability of the pyrolysis main furnace on both sides under the continuous pyrolysis working condition.

Description

Technical Field

[0001] This invention relates to the field of biomass thermochemical conversion and carbon removal technology, specifically to a continuous pyrolysis biochar production sealed system and method. Background Technology

[0002] In the process of industrial continuous pyrolysis to produce biochar, the pyrolysis furnace usually needs to maintain a low-oxygen or anaerobic environment to avoid undesirable oxidation reactions of biomass raw materials before or during pyrolysis, and to reduce the risk of backfire, combustion or explosion caused by contact between high-temperature combustible gases and air.

[0003] Existing continuous pyrolysis devices typically use airlock valves, single-stage screw conveyors, or a combination of both to isolate oxygen at the feed end. However, for biomass materials with low bulk density, easy bridging, and easy entanglement, such as straw, fruit shells, and sawdust, relying solely on airlock valves or ordinary screw conveyor structures often makes it difficult to form a stable and reliable long-path sealing zone. This can easily lead to air seeping into the pyrolysis furnace along material pores, equipment gaps, or conveying channels.

[0004] On the other hand, the biochar discharged after pyrolysis is usually still at a high temperature. If the oxygen barrier at the discharge end is insufficient, or the cooling path is too short or the temperature drop is not sufficient, the high-temperature biochar is at risk of oxidation, spontaneous combustion, or even local high-temperature failure after contact with the outside air, which will affect the safety of system operation and the stability of product quality.

[0005] In existing technologies, the feed end seal and the discharge end seal are often designed as independent local structures, lacking a system-level solution that coordinates the overall operation of the pyrolysis main furnace. Especially under conditions where continuous feeding, continuous pyrolysis, and continuous discharge occur simultaneously, relying solely on a single valve, a single spiral, or a local cooling component makes it difficult to simultaneously meet the comprehensive requirements of oxygen isolation during feeding, stable operation within the furnace, oxygen isolation during high-temperature discharge, and continuous discharge.

[0006] Therefore, there is a need in the field for a sealing system and method for continuous pyrolysis biochar production, which improves the overall sealing capacity and continuous operation reliability of both sides of the pyrolysis main furnace without significantly increasing the system complexity by coordinating the design of the mechanical plug seal on the feed side, the granular char seal on the discharge side, and the cooling path. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a sealing system and method for continuous pyrolysis biochar production, which solves the problems of insufficient sealing capacity at the feed and discharge ends, easy air infiltration into the pyrolysis main furnace, easy contact between high-temperature biochar at the discharge end and air, and insufficient stability in continuous operation in existing continuous pyrolysis devices.

[0008] The technical means adopted by this invention to solve its technical problem is: a continuous pyrolysis biochar production sealed system, including a feeding assembly, a pyrolysis main furnace, and a discharging assembly, wherein the discharging end of the feeding assembly is connected to the feeding port of the pyrolysis main furnace, and the feeding end of the discharging assembly is connected to the discharging port of the pyrolysis main furnace, characterized in that: The feeding assembly includes a feeding cylinder and a feeding screw disposed in the feeding cylinder; the feeding screw is provided with a variable pitch compression structure on the side near the pyrolysis main furnace, which is used to axially compress the input biomass material, so that the biomass material forms a mechanical plug sealing section in the feeding cylinder. The discharge assembly includes a discharge cylinder and a discharge screw disposed within the discharge cylinder; the discharge cylinder is inclined upward along the material conveying direction, and the discharge screw is used to convey the biochar discharged from the pyrolysis main furnace upward along the discharge cylinder, so that the biochar forms a granular carbon sealing section within the discharge cylinder. The mechanical feed plug sealing section and the granular carbon sealing section are located on the feed side and discharge side of the pyrolysis main furnace, respectively.

[0009] In some embodiments, the axial compression ratio of the variable pitch compression structure is 2.0-4.5; and its effective compression length is not less than 6 times the outer diameter of the feed screw.

[0010] In some embodiments, the upward tilt angle of the discharge cylinder is 30°-60°.

[0011] In some embodiments, the discharge cylinder includes a jacketed cylinder structure, the discharge screw includes a hollow screw shaft, the jacketed cylinder structure is connected to the coolant conveying device, and the hollow screw shaft is connected to the coolant conveying device through a rotary joint.

[0012] In some embodiments, the center position of the discharge end of the discharge cylinder is higher than the center position of the end that is connected to the pyrolysis main furnace, and the vertical height difference between the two is not less than the inner diameter of the discharge cylinder.

[0013] In some embodiments, the feeding assembly is connected to an inert protective gas supply device, which is connected to the inside of the feeding cylinder via an air inlet channel, and the air outlet of the air inlet channel is located at or near the axial middle position of the variable pitch compression structure, so as to form an inert gas filling section at that position.

[0014] In some embodiments, a feed star-shaped airlock valve is provided upstream of the feeding assembly. The feed port of the feed star-shaped airlock valve is offset relative to its rotation center axis, and a shearing blade structure is provided on the edge of its rotor blades.

[0015] In some embodiments, the discharge end of the feeding assembly is connected to the pyrolysis main furnace along the circumferential tangential direction of the pyrolysis main furnace.

[0016] In some embodiments, the sum of the effective length of the mechanical plug sealing section measured along the feeding direction and the effective length of the granular carbon sealing section measured along the discharging direction is not less than the effective stroke length of the reaction zone inside the pyrolysis main furnace measured along the material propulsion direction.

[0017] The technical means adopted by this invention to solve its technical problem is: a continuous pyrolysis biochar production method, the method comprising: S1: Continuously supply biomass material to the feeding assembly so that the biomass material enters the feeding cylinder; S2: The biomass material is axially compressed through the variable pitch compression structure of the feeding screw, and a mechanical plug sealing section is formed and maintained in the feeding cylinder; S3: The material processed by the feeding assembly is sent into the pyrolysis main furnace for continuous pyrolysis reaction; S4: The biochar discharged from the pyrolysis main furnace is conveyed upward along the upwardly inclined discharge cylinder by the discharge screw, and the biochar forms a granular carbon sealing section in the discharge cylinder. S5: During continuous feeding and continuous discharging, the two ends of the pyrolysis main furnace are sealed by the mechanical feed plug sealing section and the granular carbon sealing section.

[0018] The beneficial effects of this invention are: (1) By forming a mechanical material plug sealing section through the variable pitch compression structure on the feed side, the local material density in the feed channel can be increased, and the possibility of air penetrating to the main furnace side through the material pores can be reduced. (2) By cooperating with the discharge screw on the discharge side, a granular carbon seal section is formed under continuous discharge conditions, and a continuously updated material sealing path can be constructed on the discharge side. (3) By coordinating the design of the sealing path on the feed side, the sealing path on the discharge side, and the spatial relationship of the reaction zone inside the main furnace, the overall operational stability of the system under continuous feeding, continuous pyrolysis and continuous discharge conditions can be improved. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a continuous pyrolysis biochar production sealing system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the feeding assembly structure shown in an embodiment of the present invention; Figure 3 This is a schematic diagram of the material discharge assembly structure shown in an embodiment of the present invention; Figure 4This is a schematic diagram showing the vertical height difference H on the discharge side, the inner diameter D of the discharge cylinder, and the upward inclination arrangement in this invention. Figure 5 This is a schematic diagram showing the measurement of the effective length of the mechanical plug sealing section, the effective length of the granular carbon sealing section, and the effective stroke length of the internal reaction zone of the pyrolysis main furnace in this invention. Figure 6 This is a flowchart illustrating a continuous pyrolysis biochar production method according to an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached drawings: 100-Pyrolysis main furnace; 200-Feeding assembly; 210-Feeding cylinder; 220-Feeding screw; 221-Variable pitch compression structure; 222-Mechanical feed plug sealing section; 230-Feeding star-shaped airlock valve; 240-Inert protective gas supply device; 241-Air inlet channel; 242-Inert gas filling section; 300-Discharge assembly; 310-Discharge cylinder; 311-Jacket cylinder structure; 320-Discharge screw; 321-Hollow screw shaft; 330-Particle carbon sealing section; 340-Coolant conveying device; 341-Rotary joint.

[0021] In the figure, H represents the vertical height difference between the center position of the discharge end of the discharge cylinder and the center position of the end connected to the pyrolysis main furnace; D represents the inner diameter of the discharge cylinder; L_in represents the effective length of the mechanical plug sealing section measured along the feeding direction; L_char represents the effective length of the granular carbon sealing section measured along the discharge direction; and L_R represents the effective stroke length of the reaction zone inside the pyrolysis main furnace measured along the material propulsion direction. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0024] In this specification, "feeding direction" refers to the direction of movement of biomass material from the feeding assembly into the pyrolysis main furnace; "discharge direction" refers to the direction in which the pyrolyzed biochar enters the discharge assembly from the pyrolysis main furnace and moves towards the discharge end; and "material propulsion direction" refers to the main propulsion direction of the material in the reaction zone inside the pyrolysis main furnace.

[0025] In this specification, "mechanical plug sealing section" refers to a material section formed inside the feed cylinder by axial compression of biomass material by a variable pitch compression structure, which increases bulk density and can serve as part of the sealing path on the feed side.

[0026] In this specification, "granular char sealing section" refers to a section of material within the discharge cylinder, formed by an upwardly inclined discharge cylinder and a discharge screw, allowing the pyrolyzed biochar to continuously accumulate under the combined effects of upward conveying and gravity descent during transport. This granular char sealing section can be dynamically updated under continuous discharge conditions, but its effective length can be determined along the discharge direction at any given time.

[0027] In this specification, "the effective length of the mechanical plug sealing section measured along the feeding direction" refers to the length measured from the starting position to the ending position of the mechanical plug sealing section along the feeding direction; "the effective length of the granular carbon sealing section measured along the discharge direction" refers to the length measured from the discharge port of the pyrolysis main furnace to the end position of the continuous granular carbon accumulation state inside the discharge cylinder along the discharge direction; "the effective stroke length of the reaction zone inside the pyrolysis main furnace measured along the material propulsion direction" refers to the effective reaction length of the main reaction zone inside the pyrolysis main furnace along the material propulsion direction.

[0028] In some implementations, the effective length can be determined not only through observation during shutdown or disassembly inspection, but also indirectly by combining operating parameters reflecting the material filling state inside the cylinder, such as the axial temperature distribution T(x) on the outer wall of the cylinder, changes in the discharge screw drive torque, changes in internal pressure of the discharge cylinder, or material level detection signals. This helps determine the boundary position and effective length of the granular carbon seal section. In one example, the PLC control system acquires the axial temperature T(x) at multiple points on the discharge cylinder. When the axial temperature gradient change rate dT / dx exceeds a preset threshold and the screw shaft torque M ≥ M_set, the point is determined to be the boundary position of the granular carbon seal section, and the effective length L_char of the granular carbon seal section is calculated. The effective length L_char refers to the continuous material coverage area where, at the rated operating frequency, the discharge screw torque reaches the set threshold M_set and the axial temperature gradient of the cylinder changes significantly.

[0029] like Figure 1As shown in the figure, the present invention provides a structural schematic diagram of a continuous pyrolysis biochar production sealing system, including a feeding component 200, a pyrolysis main furnace 100 and a discharging component 300. The discharging end of the feeding component 200 is connected to the feeding port of the pyrolysis main furnace 100, and the feeding end of the discharging component 300 is connected to the discharging port of the pyrolysis main furnace 100. See Figure 2 The feeding assembly 200 includes a feeding cylinder 210 and a feeding screw 220 disposed within the feeding cylinder. The feeding screw 220 is provided with a variable pitch compression structure 221 on the side near the pyrolysis main furnace 100, which is used to axially compress the input biomass material, so that the biomass material forms a mechanical plug sealing section 222 within the feeding cylinder 210; See Figure 3 The discharge assembly 300 includes a discharge cylinder 310 and a discharge screw 320 disposed within the discharge cylinder 310. The discharge cylinder 310 is inclined upward along the material conveying direction. The discharge screw 320 is used to convey the biochar discharged from the pyrolysis main furnace 100 upward along the discharge cylinder 310. During this process, some of the biochar falls back and accumulates within the discharge cylinder 310 under the action of gravity to form a granular char sealing section 330. The mechanical feed plug sealing section 222 and the granular carbon sealing section 330 are located on the feed side and discharge side of the pyrolysis main furnace 100, respectively.

[0030] Specifically, biomass material enters the feed cylinder 210 from the external hopper, and the feed screw 220 begins to rotate, driving the material forward. When the material reaches the variable pitch compression structure 221 area, the pitch gradually decreases, forcing the material to accumulate in a smaller space and be compacted to form a mechanical plug sealing section 222. This high-density material plug almost fills the entire cross-section of the feed cylinder, and even if a small amount of air enters from upstream, it will be blocked by the plug and difficult to pass through. After compression, the material continues to move forward and eventually falls into the pyrolysis main furnace 100. Inside the pyrolysis main furnace 100, the material is heated and decomposed in an oxygen-free or oxygen-deficient environment to generate biochar and combustible gas. The high-temperature biochar is discharged from the outlet of the pyrolysis main furnace 100 into the discharge cylinder 310.

[0031] The discharge cylinder 310 tilts upwards and the discharge screw 320 rotates continuously, pushing the biochar upwards. However, some of the biochar cannot be completely pushed to the top due to gravity and instead falls back and accumulates in the lower middle part of the tilted section. These accumulated particles form a dynamically balanced sealing layer, namely the particle carbon seal section 330. External air must pass through this particle accumulation layer before entering the pyrolysis main furnace 100. The tiny pores between the particles and the constantly updated accumulation state make it difficult for air to penetrate. In this way, the mechanical feed plug on the feed side and the particle carbon seal on the discharge side work together to seal both ends of the pyrolysis main furnace 100.

[0032] In this embodiment, a high-density material plug is formed by mechanical compression on the feed side, and a granular self-sealing layer is formed by gravity accumulation on the discharge side. The two work together to achieve reliable oxygen isolation at both ends of the pyrolysis main furnace 100 under continuous feeding and continuous discharging conditions. This method does not rely on complex valves or external dynamic sealing systems, significantly reducing system complexity and maintenance costs. At the same time, the mechanical plug sealing section 222 uses the material to be processed itself as the sealing medium, while the granular carbon seal 330 uses the product biochar itself as the sealing medium, achieving an organic unity of sealing and material conveying functions.

[0033] In some embodiments, see continue to see Figure 2 As shown, the feeding assembly 200 is connected to an inert protective gas supply device 240. The inert protective gas supply device 240 communicates with the inside of the feeding cylinder 210 via an air inlet channel 241, and the outlet position of the air inlet channel 241 is located at or near the axial center of the variable pitch compression structure 221, so as to form an inert gas filling section 242 at that position. Preferably, the inert protective gas can be nitrogen, carbon dioxide, or other suitable protective gases.

[0034] In some embodiments, the axial midpoint or its vicinity may be located within a predetermined range on both sides of the axial center point of the effective compression section, for example, within the range of 30% to 70% of the total length of the effective compression section. The material in this range has usually been pre-compacted but has not yet entered the more compacted end region near the main furnace. Introducing inert protective gas here helps to form a local inert gas filling section 242 by utilizing the blocking effect of the preceding and following material sections, and improves the overall oxygen isolation state on the feed side.

[0035] In one specific embodiment, the inert protective gas supply device 240 continuously introduces nitrogen gas into the feed cylinder 210. The nitrogen pressure is slightly higher than the working pressure inside the feed cylinder 210, approximately 1.1 atmospheres. When the material enters through the beginning of the compression section, it has already been preliminarily compacted and has a certain degree of airtightness. After the nitrogen gas is injected from the middle position, due to the high-density material blocking both ends, it is not easy for a large amount to escape to both ends, but rather a nitrogen-rich environment is formed in this local area. The oxygen volume fraction in this area is diluted to below 2%, and at the same time, the nitrogen gas also permeates into the tiny pores of the material particles, further displacing the residual air in the pores. In this way, the amount of oxygen carried by the material before entering the mechanical plug sealing section 222 is greatly reduced, thereby reducing the oxygen isolation burden of the mechanical plug sealing section 222 and improving the overall sealing margin.

[0036] This embodiment forms a series double-sealing structure by combining the inert gas filling section 242 and the mechanical plug sealing section 222. The mechanical plug sealing section 222 mainly relies on physical blocking, while the inert gas filling section 242 mainly relies on creating a chemically inert environment. The two complement each other, significantly improving the oxygen isolation capacity on the feed side. By setting the air inlet position in the middle of the variable pitch compression structure 221, the self-sealing effect of the compressed material is cleverly utilized to reduce the consumption of inert gas. Compared with the traditional method of directly introducing protective gas at the feed inlet, this method uses less gas and achieves better results.

[0037] In some embodiments, the axial compression ratio of the variable pitch compression structure 221 is 2.0-4.5; and its effective compression length is not less than 6 times the outer diameter of the feed screw 220.

[0038] Among them, the axial compression ratio is a structural parameter used to characterize the ability of the variable pitch compression structure 221 to increase the bulk density of materials. It is achieved by changing the screw propulsion pitch or the pitch gradually changing. Optionally, the axial compression ratio can be designed with an overall gradual pitch design, that is, the pitch changes uniformly from the beginning to the end according to a fixed decrease rate. Alternatively, a multi-stage stepped compression design can be adopted, that is, the compression section is divided into multiple sub-sections, the pitch in each sub-section is constant, but the pitch of each subsequent section is significantly reduced compared to the previous section, thereby achieving segmented compression.

[0039] Effective compression length refers to the axial distance traveled by the variable pitch structure 221 from the start of compression to the end of compression; the outer diameter of the feed screw 220 refers to the diameter of the outermost edge of the screw blade.

[0040] When the compression ratio is in the range of 2.0 to 4.5, the material can be fully compacted to form a sufficiently dense plug without causing the material to clump or jam the screw due to excessive compression. Within this range, the pores between the material particles are greatly compressed, and air cannot pass through the pores to form a continuous flow path.

[0041] An effective compression length of more than 6 times the outer diameter means that the material has sufficient travel to complete the gradual compression process. If the compression section is too short, the material is compressed rapidly in a short time, which can easily cause local blockage and uneven internal stress, affecting the sealing stability. Sufficient compression length allows the material to smoothly transition from a loose state to a high-density state, forming a uniform and stable mechanical plug sealing section 222.

[0042] In one exemplary embodiment, for agricultural waste materials with a pre-treated particle size of less than 20 mm, a feed screw 220 with an outer diameter of 160 mm can be used, and the effective compression section length can be set to approximately 1500 mm, which is approximately 9.3 times the outer diameter of the screw. Simultaneously, the variable pitch compression ratio can be set to approximately 2.5:1. Under these conditions, the bulk density of the material can be increased to more than 1.8 times the original density, the pore connectivity of the material is significantly reduced, and airtightness tests show a significant reduction in convective air permeation from the outside to the main furnace side, thereby improving the formation stability of the mechanical plug sealing section 222. The above data are merely examples and do not constitute a limitation on the scope of protection of this invention.

[0043] This embodiment ensures the stability of the mechanical plug sealing section 222 and the reliability of the seal by precisely defining the compression ratio and compression length. Too low a compression ratio will result in insufficient plug density and ineffective oxygen isolation, while too high a compression ratio may cause excessive friction and heat generation within the compression section, leading to premature combustion or material degradation. A compression ratio range of 2.0 to 4.5 has been experimentally verified to adapt to the characteristics of most biomass feedstocks, while the length requirement of not less than 6 times the outer diameter ensures a smooth compression process and plug uniformity, preventing localized failures caused by excessively rapid compression.

[0044] In some embodiments, the upward tilt angle of the discharge cylinder 310 is 30°-60°.

[0045] The upward tilt angle refers to the angle at which the central axis of the discharge cylinder 310 is tilted upward relative to the horizontal plane. This angle determines the conveying and accumulation behavior of biochar within the discharge cylinder 310. When the tilt angle is less than 30 degrees, the discharge cylinder 310 is nearly horizontal. At this point, the effect of gravity on the material's fall is weak, and most of the biochar is directly pushed to the discharge end by the discharge screw, making it difficult to form a stable and sufficiently long granular char sealing section within the cylinder, resulting in poor sealing. When the tilt angle is greater than 60 degrees, the discharge cylinder 310 is nearly vertical. At this point, the effect of gravity is too strong, and most of the biochar slides down the cylinder wall back into the pyrolysis main furnace 100 before the screw blades can effectively push it upward, leading to difficulties in discharge or even blockage of the discharge port. A balance is achieved within the tilt angle range of 30°-60°. Within this range, the discharge screw 320 can effectively convey most of the material upward, while the remaining material falls naturally under gravity, forming a dynamically balanced accumulation layer at the bottom or middle section of the cylinder, namely the granular char sealing section 330.

[0046] In one exemplary embodiment, the angle between the discharge cylinder 310 and the horizontal plane is set to 45 degrees. High-temperature biochar enters the lower end of the discharge cylinder 310 from the discharge port of the pyrolysis main furnace 100. The discharge screw 320 begins to rotate, and the screw blades push the biochar upwards at a certain rotational speed. Under the 45-degree inclination, the biochar particles are subjected to the combined force of the screw blades and their own gravity. Some particles are completely lifted by the screw blades and move upwards along the cylinder wall, eventually reaching the discharge end. Other particles, especially those near the lower part of the cylinder wall, slide downwards after moving upwards a certain distance because the component of gravity along the inclined plane is greater than the frictional force provided by the screw blades. These sliding particles meet with newly entering particles and form a local accumulation area in the lower middle part of the discharge cylinder. The height and length of this accumulation area dynamically adjust with fluctuations in the feed and discharge rates but always maintain a certain size. This dynamic accumulation layer effectively fills the gaps between the screw blades and the cylinder wall, as well as the gaps between the screw blades, thus forming a tight sealing barrier.

[0047] This embodiment utilizes an inclined arrangement and gravity to naturally form a dynamic sealing structure at the discharge end, eliminating the need for additional valves or power units and reducing equipment investment and operating energy consumption. The 30-60 degree inclination range has been experimentally verified to meet the sealing requirements of most common biochar. During continuous discharge, this structure automatically adapts to fluctuations in material flow; as the feed rate increases, the accumulation layer automatically grows, and as the discharge speed increases, the accumulation layer shortens accordingly, while always maintaining the sealing function.

[0048] In some embodiments, continue reading Figure 3 As shown, the discharge cylinder 310 includes a jacketed cylinder structure 311, and the discharge screw 320 includes a hollow screw shaft 321. The jacketed cylinder structure 311 is connected to the coolant conveying device 340, and the hollow screw shaft 321 is connected to the coolant conveying device 340 through a rotary joint 341.

[0049] The jacketed cylinder structure 311 refers to a closed cavity formed by encasing an outer shell outside the outer wall of the discharge cylinder 310. The coolant delivery device 340 communicates with this cavity, and the coolant circulates within it, exchanging heat with the biochar inside the cylinder wall to remove heat. The hollow spiral shaft 321 refers to a shaft with a hollow interior, forming a channel for the flow of cooling medium. The coolant enters the hollow spiral shaft 321 through the rotary joint 341 and flows inside the shaft, exchanging heat with the surrounding biochar through the shaft wall. In this way, the biochar in the discharge cylinder 310 is simultaneously cooled from both the outer wall of the cylinder and the interior of the spiral shaft, forming a dual heat exchange path. This structure significantly improves cooling efficiency and uniformity, avoiding the problem of slow cooling of biochar near the shaft center when cooled only from the outside.

[0050] Specifically, biochar at approximately 500°C continuously enters the discharge cylinder 310 from the outlet of the pyrolysis main furnace 100. A coolant conveying device 340 simultaneously supplies coolant at 20°C to both the jacket cylinder structure 311 and the hollow spiral shaft 321. The coolant in the jacket cylinder structure 311 flows from one end of the discharge cylinder 310 to the other, absorbing heat transferred through the cylinder wall. The coolant in the hollow spiral shaft 321 enters through the rotary joint 341 and flows along the inside of the spiral shaft, absorbing heat transferred through the shaft wall. Driven upwards by the discharge spiral 320, the biochar simultaneously releases heat to the cylinder wall and the spiral shaft. After a certain distance, the temperature of the biochar significantly decreases to below approximately 100°C. Simultaneously, the coolant in the jacket cylinder structure 311 and the hollow spiral shaft 321, after its temperature rises, flows out and is sent to a cooling tower for cooling and recycling. This dual cooling process ensures that the biochar is already within a safe temperature range when it reaches the discharge end, preventing spontaneous combustion or severe oxidation even when exposed to air.

[0051] In some embodiments, the coolant can be water, an aqueous solution of ethylene glycol, an aqueous solution of propylene glycol, or other suitable heat exchange media. For systems with different processing capacities, discharge temperatures, and discharge rates, different heat exchange effects can be achieved by adjusting the coolant flow rate, inlet temperature, and effective length of the discharge assembly. The dual heat exchange path formed by the jacketed cylinder structure 311 and the hollow spiral shaft 321 can improve the continuous cooling capacity during the discharge process and reduce the risk of oxidation or self-heating of the high-temperature biochar when it comes into contact with air during subsequent unloading, packaging, or storage.

[0052] In this embodiment, the discharge-side cooling structure and the granular biochar sealing section 330 can work together: on the one hand, the discharge assembly 300 serves as the conveying path for high-temperature biochar; on the other hand, the discharge assembly 300 forms a discharge-side sealing path through its upward tilting arrangement and granule accumulation. Thus, the discharge path not only undertakes the functions of material conveying and cooling, but also the sealing function for the discharge side of the pyrolysis main furnace 100.

[0053] In some embodiments, such as Figure 4 As shown, the center position of the discharge end of the discharge cylinder 310 is higher than the center position of the end that is connected to the pyrolysis main furnace 100, and the vertical height difference H between the two is not less than the inner diameter D of the discharge cylinder 310.

[0054] This geometric condition ensures that the inclination and length of the discharge cylinder 310 meet a certain proportional relationship, and a sufficient vertical height difference H allows the particle carbon sealing section 330 to have enough space to form and maintain under the action of gravity. If the height difference is too small, the discharge cylinder may be too flat, causing the particles to not fall back effectively and form a continuous accumulation; if the height difference is large enough, the inside of the discharge cylinder can accommodate a long particle accumulation area, which provides a more complete and stable coverage of the cylinder cross-section.

[0055] Preferably, H / D can be greater than or equal to 1. Under the combined action of upward conveying and gravity fall, biochar particles have a natural accumulation tendency. When H is not less than D, it is more conducive to the falling particles forming a continuous cover on the cross-section of the discharge cylinder, and to compensating for the instantaneous gaps between the spiral blades during operation fluctuations, thereby improving the continuous stability of the granular char sealing section 330.

[0056] In some embodiments, a feed star-shaped airlock valve 230 is provided upstream of the feed assembly 200. The feed port of the feed star-shaped airlock valve 230 is offset relative to its rotation center axis, and a shearing blade structure is provided on the edge of its rotor blades.

[0057] The offset setting refers to the fact that the centerline of the feed inlet does not coincide with the rotation centerline of the rotor. This design ensures that when material enters, it does not directly impact the middle of the blades but is offset to one side, thus reducing the positive pressure of the material on the rotor and lowering the risk of jamming. The shearing blade structure refers to the blade edges being machined into sharp blade shapes or having blades additionally installed on the blade edges. When long fibers or sheet-like materials are entangled between the blades or stuck between the blades and the housing, the shearing force generated by the rotor's rotation can cut these materials, thereby preventing blockage and jamming.

[0058] Specifically, the biomass feedstock to be processed contains a large amount of corn stalk fiber, which can reach 50 mm or even longer in length. The feedstock first enters the offset feed port of the star-shaped airlock valve 230. Because the feed port is offset, the material first falls on the front half of the rotor rather than the center, which makes it easier for the material to be cut rather than squeezed when the blades cut into it. At the same time, the shearing blade structure on the edge of the rotor blades forms a shearing action similar to scissors when the blades rotate past the edge of the shell inlet. Once the long fiber material is caught between the blade and the shell, it is cut off by the sharp blades and thus smoothly enters the blade chamber. The cut short fibers continue to rotate with the rotor and eventually fall into the feed cylinder. The whole process avoids the fiber from getting tangled on the shaft or stuck on the blade tip, which would cause the airlock valve to overheat or stop rotating.

[0059] This embodiment effectively solves the problem of blockage at the airlock valve in low-density, easily entangled biomass feedstock by combining an offset feed inlet and a shearing blade structure. This improves the feeding stability and long-term operational reliability of the continuous pyrolysis system. Furthermore, the feed star-shaped airlock valve 230 itself has a certain airlock function, forming a three-stage sealing structure with the subsequent mechanical plug sealing section 222 and inert gas filling section 242. This progressively reduces the oxygen content, ensuring a high degree of sealing at the feed end of the pyrolysis main furnace.

[0060] In some embodiments, the discharge end of the feeding assembly 200 is connected to the pyrolysis main furnace 100 along the circumferential tangential direction of the pyrolysis main furnace 100.

[0061] This tangential introduction method gives the material a certain angular velocity when it enters the main furnace. The material does not rush straight into the material propulsion direction inside the main furnace, but is thrown out along the tangential direction of the inner wall of the furnace. In this way, the material can land smoothly on the surface of the material layer inside the furnace or naturally merge with the direction of the material flow inside the furnace without generating a violent frontal impact.

[0062] This embodiment reduces the disturbance of the material layer and gas flow field inside the pyrolysis main furnace 100 by the tangential feeding method, which is beneficial to maintaining the stability of the pyrolysis process. At the same time, this connection method reduces the possibility of material directly impacting the furnace wall opposite the feed inlet, extending the service life of the furnace body. The tangential connection with the mechanical plug sealing section 222 also avoids the problem of the plug suddenly opening at the outlet and destroying the sealing effect due to improper feeding direction.

[0063] In some embodiments, such as Figure 5 As shown, the sum of the effective length L_in of the mechanical plug sealing section 222 along the feeding direction and the effective length L_char of the granular carbon sealing section 330 along the discharging direction is not less than the effective stroke length L_R of the internal reaction zone of the pyrolysis main furnace 100 along the material propulsion direction, that is, L_in + L_char ≥ L_R.

[0064] This relationship characterizes the system-scale matching relationship between the feed-side sealing path and the discharge-side sealing path relative to the internal reaction zone of the main furnace. When the sum of the effective length of the mechanical plug sealing section 222 and the effective length of the granular carbon sealing section 330 is not less than the effective travel length of the internal reaction zone of the pyrolysis main furnace 100, a continuous sealing path covering both ends of the reaction zone can be formed, thereby reducing the possibility of pressure fluctuations inside the main furnace propagating to the feed and discharge ends and improving the stability of continuous low-oxygen pyrolysis operation.

[0065] Specifically, in a pilot plant, the effective travel length of the reaction zone inside the pyrolysis main furnace 100 is 3.0 meters. Measurements and calibrations show that the effective length of the mechanical plug sealing section 222 along the feed direction is 1.55 meters, and the effective length of the granular carbon seal section 330 on the discharge side along the discharge direction is 1.58 meters, totaling 3.13 meters, which is greater than 3.0 meters. During continuous operation, complex pyrolysis reactions occur inside the pyrolysis main furnace 100, generating pressure fluctuations. Without a sufficiently long sealing path, these pressure fluctuations might push the sealing sections apart, causing air infiltration. However, since the total length of the sealing sections on both sides exceeds the length of the reaction zone, any pressure disturbance inside the main furnace must overcome a long sealing resistance before propagating to the outside. The compacted material in the mechanical plug sealing section 222 and the accumulated particles in the granular carbon seal section 330 together form a high-resistance flow channel. The pressure wave gradually attenuates during propagation and cannot penetrate the entire sealing section. Therefore, the main furnace can maintain a stable slightly negative or slightly positive pressure state for a long time without sealing failure.

[0066] This embodiment establishes a collaborative design principle that the sum of the feed-side sealing length and the discharge-side sealing length must match the length of the main furnace reaction zone. This principle elevates the sealing performance of the pyrolysis system from the level of local components to the level of the entire system. After meeting this length matching condition, the pressure stability inside the pyrolysis main furnace 100 is significantly improved, and its resistance to external air infiltration is greatly enhanced. Compared with designs that do not meet this condition, the reliability and safety of continuous operation are substantially improved. Furthermore, this principle provides a quantifiable theoretical basis for the design of pyrolysis units of different scales.

[0067] In one exemplary embodiment, the continuous pyrolysis biochar production sealing system of the present invention was verified by pilot-scale continuous operation. The experimental conditions were as follows: the biomass raw material was agricultural waste straw with a pretreated particle size of less than 20 mm, and the initial bulk density was approximately 120 kg / m³. 3 The moisture content is 12% to 15%; the effective stroke length L_R of the reaction zone inside the pyrolysis main furnace 100 along the material feeding direction is approximately 3.0m, the pyrolysis temperature is controlled at 550±20℃, and the target oxygen content inside the main furnace is less than 1 vol%; the outer diameter of the feed screw 220 is 160mm, the effective compression section length is 1500mm, and the axial compression ratio is 2.5:1; the discharge cylinder 310 is set at a 45° upward inclination angle along the material conveying direction, and the ratio of the vertical height difference H between the center position of the discharge end of the discharge cylinder 310 and the center position of the end connected to the pyrolysis main furnace 100 to the inner diameter D of the discharge cylinder is 1.2, where the inner diameter D of the discharge cylinder is 200mm; the cooling water inlet temperature is 25℃, and the flow rate is 4L / min to 5L / min; the inert protective gas is nitrogen, with a flow rate of approximately 2Nm³. 3 / h, the air intake position is set near the axial center of the variable pitch compression structure 221.

[0068] Continuous operation verification results show that after the action of the variable pitch compression structure 221, the bulk density of the material on the feed side is reduced from approximately 120 kg / m³. 3 Increased to approximately 215 kg / m 3 Up to 225kg / m 3 The porosity of the material is reduced from approximately 62% to approximately 30% to 34%, and the tendency of air on the feed side to permeate into the pyrolysis main furnace 100 along the material pore channels is significantly reduced. Combined with the inert gas filling section 242 located in the middle region of the variable pitch compression structure 221, the oxygen content inside the pyrolysis main furnace 100 can be stably maintained in the range of approximately 0.3 vol% to 0.6 vol%. On the discharge side, when the discharge cylinder 310 is set at a 45° upward inclination angle and the ratio of the vertical height difference H to the inner diameter D of the discharge cylinder (H / D) is 1.2, the effective length L_char of the granular char sealing section 330 can be maintained in the range of approximately 1.52 m to 1.62 m. When the high-temperature biochar is discharged from the pyrolysis main furnace 100, the temperature is approximately 455°C to 470°C. After passing through the dual cooling path formed by the jacket cylinder structure 311 and the hollow spiral shaft 321, the temperature at the discharge end can be reduced to approximately 68°C to 78°C. In this embodiment, the effective length L_in of the mechanical plug sealing section 222 on the feed side is approximately 1.55m, and the effective length L_char of the granular carbon sealing section 330 on the discharge side is approximately 1.58m, with a sum of approximately 3.13m, which is greater than the effective travel length L_R of the internal reaction zone of the pyrolysis main furnace 100. Under the condition that the length matching relationship L_in + L_char ≥ L_R is satisfied, the system has operated continuously for 240 hours without any backfire, spontaneous combustion, or significant sealing failure events, indicating that this length matching relationship is beneficial to improving the sealing stability and operational safety under continuous low-oxygen pyrolysis operation.

[0069] To further verify the aforementioned length matching relationship and the impact of the vertical height difference setting on the discharge side on sealing stability, comparative observations were conducted under essentially identical operating conditions. In one comparative example, by shortening the effective length of the granular carbon seal section 330 on the discharge side, the sum of the effective length L_in of the mechanical plug seal section 222 on the feed side and the effective length L_char of the granular carbon seal section 330 on the discharge side satisfies the relationship L_in + L_char < L_R. The results show that the axial boundary fluctuation of the granular carbon seal section 330 increases, the oxygen content fluctuation range near the discharge end of the pyrolysis main furnace 100 increases, pressure disturbances inside the main furnace are more easily propagated along the discharge channel direction, and the risk of instantaneous gas leakage on the discharge side increases. In another comparative example, by reducing the vertical height difference between the center position of the discharge end of the discharge cylinder 310 and the center position of the end connected to the pyrolysis main furnace 100, the ratio of the vertical height difference H to the inner diameter D of the discharge cylinder satisfies the relationship H / D < 1. The results show that the continuous coverage of the granular carbon accumulation zone within the discharge cylinder 310 by the cylinder cross-section is reduced, and the effective length stability of the granular carbon sealing section 330 is weakened. The above comparative results demonstrate that geometrical settings satisfying the relationships L_in + L_char ≥ L_R and H / D ≥ 1 are beneficial for forming a stable and coordinated sealing structure.

[0070] The above continuous operation verification results show that, through the coordinated arrangement of the mechanical plug sealing section 222 on the feed side, the inert gas filling section 242, the granular carbon sealing section 330 on the discharge side, and the cooling path structure on the discharge side, the present invention can improve the oxygen isolation capacity at both ends of the pyrolysis main furnace 100, the safe discharge capacity of high-temperature biochar on the discharge side, and the overall continuous operation reliability of the system under the condition of simultaneous continuous feeding, continuous pyrolysis, and continuous discharge. In some embodiments, the dynamic boundary and sealing state of the granular carbon sealing section 330 can be judged online by combining operating parameters such as the driving torque M of the discharge screw 320, the axial temperature gradient dT / dx of the discharge cylinder 310, and the changes in oxygen content or pressure signal at the discharge end. This provides physical parameter basis for monitoring and recording the continuous pyrolysis operation status and evaluating the operational stability, and further illustrates that the length matching relationship is not an empirically selected parameter, but a structural collaborative design condition related to the sealing stability of the continuous pyrolysis system.

[0071] The system of this invention is applicable to straw, wood, fruit shells, garden waste, and other biomass raw materials suitable for continuous pyrolysis charcoal production. In practical applications, the feed screw compression ratio, compression section length, discharge cylinder inclination angle, vertical height difference, and coolant parameters can be adjusted according to parameters such as raw material particle size, moisture content, initial bulk density, and pyrolysis temperature.

[0072] This invention also provides a continuous pyrolysis biochar production method, which is based on the aforementioned continuous pyrolysis biochar generation sealed system, such as... Figure 6 As shown, it includes the following steps: S1: Biomass material is continuously supplied to the feeding assembly 200, so that the biomass material enters the feeding cylinder 210; S2: The biomass material is axially compressed by the variable pitch compression structure 221 of the feeding screw 220, and a mechanical plug sealing section 222 is formed and maintained in the feeding cylinder 210. S3: The material processed by the feeding component 200 is sent into the pyrolysis main furnace 100 for continuous pyrolysis reaction; S4: The biochar discharged from the pyrolysis main furnace is conveyed upward along the upwardly inclined discharge cylinder 310 by the discharge screw 320, and the biochar forms a granular carbon sealing section 330 in the discharge cylinder 310. S5: During continuous feeding and continuous discharging, the two ends of the pyrolysis main furnace are sealed by the mechanical plug sealing section 222 and the granular carbon sealing section 330.

[0073] In some preferred embodiments, the method further includes: S6: During continuous feeding, inert protective gas is introduced into the feed cylinder 210 through the air inlet channel 241 located at or near the axial middle position of the variable pitch compression structure 221, forming an inert gas filling section 242 at the location. S7: During the continuous discharge process, the high-temperature biochar in the discharge is continuously cooled by the jacketed cylinder structure 311, the hollow spiral shaft 321, the coolant conveying device 340 and the rotary joint 341. In the method of this invention, S2, S3, S4, S5, S6, and S7 can be in a continuous coupled operation state, rather than being strictly divided into mutually isolated time stages. In other words, under continuous industrial operation conditions, feed compression, inert gas introduction, in-furnace pyrolysis, discharge conveying, and discharge cooling can be carried out in parallel.

[0074] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A continuous pyrolysis biochar production sealing system, comprising a feeding assembly, a pyrolysis main furnace, and a discharging assembly, wherein the discharging end of the feeding assembly is connected to the inlet of the pyrolysis main furnace, and the feeding end of the discharging assembly is connected to the outlet of the pyrolysis main furnace, characterized in that: The feeding assembly includes a feeding cylinder and a feeding screw disposed in the feeding cylinder; the feeding screw is provided with a variable pitch compression structure on the side near the pyrolysis main furnace, which is used to axially compress the input biomass material, so that the biomass material forms a mechanical plug sealing section in the feeding cylinder. The discharge assembly includes a discharge cylinder and a discharge screw disposed within the discharge cylinder; the discharge cylinder is inclined upward along the material conveying direction, and the discharge screw is used to convey the biochar discharged from the pyrolysis main furnace upward along the discharge cylinder, so that the biochar forms a granular carbon sealing section within the discharge cylinder. The mechanical feed plug sealing section and the granular carbon sealing section are located on the feed side and discharge side of the pyrolysis main furnace, respectively.

2. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: The axial compression ratio of the variable pitch compression structure is 2.0-4.5; and its effective compression length is not less than 6 times the outer diameter of the feed screw.

3. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: The upward tilt angle of the discharge cylinder is 30°-60°.

4. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: The discharge cylinder includes a jacketed cylinder structure, the discharge screw includes a hollow screw shaft, the jacketed cylinder structure is connected to the coolant conveying device, and the hollow screw shaft is connected to the coolant conveying device through a rotary joint.

5. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: The center position of the discharge end of the discharge cylinder is higher than the center position of the end that is connected to the pyrolysis main furnace, and the vertical height difference between the two is not less than the inner diameter of the discharge cylinder.

6. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: The feeding assembly is connected to an inert protective gas supply device. The inert protective gas supply device is connected to the inside of the feeding cylinder through an air inlet channel. The air outlet of the air inlet channel is located at or near the axial middle position of the variable pitch compression structure, so as to form an inert gas filling section at that position.

7. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: An upstream feed star-shaped airlock valve is provided for the feeding assembly. The feed port of the feed star-shaped airlock valve is offset relative to its rotation center axis, and a shearing blade structure is provided on the edge of its rotor blades.

8. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: The discharge end of the feeding assembly is connected to the pyrolysis main furnace along the circumferential tangential direction of the pyrolysis main furnace.

9. The continuous pyrolysis biochar production sealing system according to claim 1, characterized in that: The sum of the effective length of the mechanical plug sealing section measured along the feeding direction and the effective length of the granular carbon sealing section measured along the discharging direction shall not be less than the effective stroke length of the reaction zone inside the pyrolysis main furnace measured along the material propulsion direction.

10. A method for continuous pyrolysis biochar production using the continuous pyrolysis biochar production sealed system according to any one of claims 1 to 9, characterized in that, include: S1: Continuously supply biomass material to the feeding assembly so that the biomass material enters the feeding cylinder; S2: The biomass material is axially compressed through the variable pitch compression structure of the feeding screw, and a mechanical plug sealing section is formed and maintained in the feeding cylinder; S3: The material processed by the feeding assembly is sent into the pyrolysis main furnace for continuous pyrolysis reaction; S4: The biochar discharged from the pyrolysis main furnace is conveyed upward along the upwardly inclined discharge cylinder by the discharge screw, and the biochar forms a granular carbon sealing section in the discharge cylinder. S5: During continuous feeding and continuous discharging, the two ends of the pyrolysis main furnace are sealed by the mechanical feed plug sealing section and the granular carbon sealing section.

Images