Internal heating type carbonization system based on countercurrent flow heat exchange of central heating pipe

Abstract

The invention discloses an internal heating type carbonization system based on countercurrent flow heat exchange of a central heating pipe, the internal heating type carbonization system comprises a carbonization furnace, a feeding mechanism and the central heating pipe, the left end of the carbonization furnace is provided with a feeding hole, the right end of the carbonization furnace is provided with a carbon discharge hole, the feeding mechanism is communicated with the feeding hole and is used for conveying biomass raw materials into the carbonization furnace, and the central heating pipe is arranged in a hearth in a penetrating manner; the left end of the central heating pipe is connected with a combustor arranged outside the hearth, the right end of the central heating pipe is communicated with a combustion chamber arranged outside the hearth, and an air inlet is formed in the central heating pipe and located on the left side of the hearth close to the feeding port; in the hearth, the biomass raw material moves from left to right and flows with the combustible pyrolysis gas from right to left to form countercurrent flow heat exchange, the combustible pyrolysis gas generated by carbonization is recycled to the central heating pipe to be combusted for heat supply, and the unburnt pyrolysis gas can be fully combusted in the combustion chamber, so that the resource utilization of the pyrolysis gas is realized, and the energy consumption is reduced. The problems that an existing external combustion type carbonization furnace is low in heat utilization rate, uneven in material heating, high in energy consumption and waste in pyrolysis gas are fundamentally solved.

Description

Technical Field

[0001] This application relates to the field of biomass raw material carbonization technology, and in particular to an internal heating carbonization system based on countercurrent heat exchange through a central heating tube. Background Technology

[0002] Biomass carbonization is an important process for converting biomass raw materials into charcoal. Most of the existing mainstream carbonization equipment adopts an external combustion heating structure, such as setting a jacket or heating chamber outside the carbonization furnace, and achieving indirect heating by introducing high-temperature hot flue gas into the jacket / heating chamber.

[0003] The heat from this type of external combustion design needs to be conducted through the furnace wall to the furnace chamber before coming into contact with the material. The conduction path is long and there is a lot of heat loss, resulting in a generally low heat utilization rate, which can usually only reach 40%-60%. At the same time, there is a temperature gradient in the heat conduction of the furnace wall, which can easily cause uneven heating of the material in the furnace chamber, ultimately affecting the consistency of charcoal quality.

[0004] In addition, externally combusted carbonization furnaces require continuous use of external heat sources to maintain heating, resulting in high energy costs; and the combustible pyrolysis gas generated during the carbonization process is mostly directly emitted or simply treated without being fully recovered and utilized, leading to energy waste. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the existing technology and provide an internal heating carbonization system based on countercurrent heat exchange through a central heating tube.

[0006] This application provides an internally heated carbonization system based on countercurrent heat exchange using a central heating pipe, comprising: a carbonization furnace with a linearly extending furnace chamber, a feed inlet at the left end and a char outlet at the right end; a feeding mechanism connected to the feed inlet for conveying biomass raw materials into the carbonization furnace; and a central heating pipe inserted into the furnace chamber, with its left end connected to a burner located outside the furnace chamber and its right end connected to a combustion chamber located outside the furnace chamber, the central heating pipe having an air inlet located on the left side of the furnace chamber near the feed inlet; during operation, the biomass raw materials move from left to right within the furnace chamber and complete carbonization, the generated charcoal is discharged through the char outlet, and the generated combustible pyrolysis gas flows from right to left within the furnace chamber and enters the central heating pipe through the air inlet; the pyrolysis gas burns within the central heating pipe, heating the pipe wall and then radiating heat into the furnace chamber; unburned pyrolysis gas can enter the combustion chamber along the central heating pipe and burn completely within the combustion chamber.

[0007] Furthermore, the central heating tube is provided with multiple air inlets, which are distributed at intervals along the axial direction of the tube body, and the distribution density of the air inlets is greater closer to the feed inlet; and / or, the air inlets extend obliquely to guide the incoming airflow to tangentially impact the central area inside the central heating tube; and / or, the air inlets are covered with a filter cover to prevent lumpy materials from entering the central heating tube.

[0008] Furthermore, the burner is used to ignite the pyrolysis gas in the central heating tube in the initial stage. After the system is running stably, the pyrolysis gas in the central heating tube can achieve self-sustaining of the system through self-ignition. The carbonization system also includes a combustion monitoring device, which includes: a first flame detector for monitoring the combustion flame of the burner; a second flame detector located in the middle section of the central heating tube or at the entrance of the combustion chamber for monitoring the combustion flame in the self-sustaining state of the system; and a controller configured to determine the combustion state of the system based on the signals from the first and second flame detectors and adjust the operating mode of the burner accordingly. The controller is configured to execute a start-up mode, a transition mode, and a monitoring mode. In the start-up mode, the burner is ignited and preheated at a first preset power. In the transition mode, after the second flame detector detects a stable flame, the power of the burner is gradually reduced. In the monitoring mode, the system is in a self-sustaining state, and the burner is maintained at a second preset power in a constant open flame state or an intermittent operating state, where the second preset power is lower than the first preset power.

[0009] Furthermore, the combustion monitoring device also includes an emergency purge valve, which is located on the central heating tube; the controller is interlocked with the feeding mechanism and the emergency purge valve; when both the first flame detector and the second flame detector detect flameout, the controller executes an emergency shutdown procedure, including closing the feeding mechanism and opening the emergency purge valve to inject purge medium into the central heating tube.

[0010] Furthermore, a water seal device is installed on the section of the central heating pipe located between the carbonization furnace and the combustion chamber. The water seal device is used to regulate system pressure, provide a safe seal, and prevent backfire. The water seal device is equipped with a liquid level sensor and a regulating valve. The liquid level sensor is used to monitor the height of the liquid seal, and the regulating valve is connected to the liquid level sensor signal to maintain a constant liquid seal height. The carbonization furnace is equipped with a pressure sensor to monitor the gas pressure inside the furnace. An induced draft device is installed on the gas exhaust path of the carbonization furnace. The working power of the induced draft device is adjusted according to the detection signal of the pressure sensor, which can control the negative pressure atmosphere inside the carbonization furnace.

[0011] Furthermore, the carbonization furnace is a drum-type carbonization furnace, equipped with a rotary drive device. The rotary drive device is used to drive the carbonization furnace to rotate at a uniform speed and can adjust the speed of the carbonization furnace according to the state of the raw materials or the process stage. The central heating tube is fixed and does not rotate with the carbonization furnace. The central axis of the central heating tube coincides with the axis of the drum of the carbonization furnace. When the carbonization furnace rotates, the material in the furnace can fully contact the central heating tube.

[0012] Furthermore, the rotary drive includes at least two independent drive units to ensure torque balance through electrical synchronization control, thereby preventing torsional deformation of the carbonization furnace; and / or, the carbonization furnace is rotatably mounted on a base, the base including at least two pairs of support rollers, and the carbonization furnace having at least two sets of rolling rings, the carbonization furnace being rotatably supported on the support rollers by the rolling rings; and / or, the carbonization furnace is rotatably mounted on a base, the base having an adaptive self-aligning structure for compensating for deformation of the carbonization furnace caused by heat; and / or, the carbonization system also includes a speed monitoring sensor for triggering a safety interlock action when the speed is abnormal.

[0013] Furthermore, the inner wall of the carbonization furnace is provided with multiple axially extending lifting plates, which are used to lift and scatter materials during the rotation of the carbonization furnace.

[0014] Furthermore, the installation direction of the lifting plates is set at an angle to the axis of the carbonization furnace, so that the material can be fed downstream while being thrown; and / or, the shape, density or installation angle of the lifting plates are differentiated according to the temperature and functional zones inside the carbonization furnace.

[0015] Furthermore, the feed inlet and / or discharge outlet are provided with: a fixed cover, the end of the carbonization furnace being rotatably disposed within the fixed cover; a dynamic sealing mechanism, disposed between the fixed cover and the carbonization furnace, including a labyrinth seal and a flexible contact seal arranged sequentially along the gas leakage direction; the labyrinth seal includes: at least one set of labyrinth moving rings, disposed on the outer wall of the end of the carbonization furnace, capable of rotating synchronously with the carbonization furnace; at least one set of labyrinth stationary rings, disposed on the inner wall of the fixed cover, the labyrinth stationary rings and labyrinth moving rings being alternately and spaced along the axial direction, together forming a tortuous flow channel; the flexible contact seal includes: a sealing ring, sleeved on the end of the carbonization furnace and pressed between the carbonization furnace and the fixed cover; a floating pressure cap, disposed on the side of the sealing ring facing away from the labyrinth seal; and an elastic force application unit, pressed between the floating pressure cap and the fixed cover, used to provide axial pressure to the floating pressure cap so that the sealing ring presses against the carbonization furnace and the fixed cover.

[0016] This application provides an internally heated carbonization system based on countercurrent heat exchange using a central heating pipe, including a carbonization furnace, a feeding mechanism, and a central heating pipe. The carbonization furnace has a feed inlet at its left end and a char outlet at its right end. The feeding mechanism connects to the feed inlet and is used to feed biomass raw materials into the carbonization furnace. The central heating pipe passes through the furnace chamber, with its left end connected to a burner located outside the furnace chamber and its right end connected to a combustion chamber located outside the furnace chamber. An air inlet is provided on the central heating pipe, located on the left side of the furnace chamber near the feed inlet. By setting up a central heating pipe that passes through the furnace chamber and can directly contact the biomass raw materials, the heat transfer path is effectively shortened, avoiding the large amount of heat loss caused by external combustion furnace wall conduction, thus improving heat utilization and carbonization efficiency. Inside the furnace chamber, the biomass raw materials move from left to right, and the combustible pyrolysis gas flows from right to left, forming countercurrent heat exchange. The air inlet near the feed inlet of the central heating tube allows the material to receive radiant heat evenly and comprehensively throughout the carbonization process, thus avoiding localized over-carbonization or incomplete carbonization and ensuring the consistency of charcoal quality. The combustible pyrolysis gas produced during carbonization is recovered and burned in the central heating tube for heating, and the unburned pyrolysis gas can be fully burned in the combustion chamber, realizing the resource utilization of pyrolysis gas without continuous reliance on external heat sources, which helps to reduce energy consumption costs and ensures clean and safe emissions. This application provides an internal heating carbonization system based on countercurrent heat exchange of the central heating tube, which fundamentally solves the problems of low heat utilization rate, uneven material heating, high energy consumption, and pyrolysis gas waste in existing external combustion carbonization furnaces through the coordinated movement of airflow and material and the in-furnace recovery and utilization of pyrolysis gas, taking into account energy saving, environmental protection, and product stability. Attached Figure Description

[0017] Figure 1 A schematic diagram of an internal heating carbonization system based on countercurrent heat exchange through a central heating tube, provided for this application; Figure 2 This is a structural cross-sectional view of a dynamic sealing mechanism provided in this application. Detailed Implementation

[0018] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0019] This application provides an internal heating carbonization system based on countercurrent heat exchange through a central heating pipe, comprising: a carbonization furnace 1, the furnace chamber of which extends linearly, with a feed inlet at the left end and a char outlet at the right end; a feeding mechanism 2, connected to the feed inlet, for conveying biomass raw materials into the carbonization furnace 1; a central heating pipe 3, which passes through the furnace chamber, with a burner 4 located outside the furnace chamber at its left end and a combustion chamber 5 located outside the furnace chamber at its right end, and an air inlet on the central heating pipe 3, located on the left side of the furnace chamber near the feed inlet; during operation, the biomass raw materials move from left to right within the furnace chamber and complete carbonization, the generated char is discharged through the char outlet, and the generated combustible pyrolysis gas flows from right to left within the furnace chamber and enters the central heating pipe 3 through the air inlet; the pyrolysis gas burns within the central heating pipe 3, heating the pipe wall and then radiating heat into the furnace chamber; unburned pyrolysis gas can enter the combustion chamber 5 along the central heating pipe 3 and burn completely within the combustion chamber 5.

[0020] For details, please refer to Figure 1 In the illustrated embodiment, the carbonization furnace 1 is the core carbonization carrier of the system. Its furnace chamber is straight and extends in the left-right direction. The upper left side of the carbonization furnace 1 has a feed inlet that communicates with the feeding mechanism 2. The feeding mechanism 2 (which can be a belt conveyor, bucket elevator, or a silo with raised structure to allow material to fall by gravity) is used to transport biomass raw materials into the furnace chamber. The lower right side of the carbonization furnace 1 has a charcoal discharge port for discharging the charcoal produced during carbonization.

[0021] Continue to refer to Figure 1 The central heating pipe 3 runs along the furnace axis inside the furnace. The left end of the central heating pipe 3 exits the furnace and connects to the burner 4, which ignites the combustible pyrolysis gas entering the central heating pipe 3. The right end of the central heating pipe 3 exits the furnace and connects to the combustion chamber 5, which receives and burns any unburned pyrolysis gas that has passed through the central heating pipe 3. The central heating pipe 3 has an air inlet located on the left side of the furnace near the feed inlet, serving as the channel for the combustible pyrolysis gas generated inside the furnace to enter the central heating pipe 3.

[0022] When the system is working normally, the biomass raw material enters the furnace of the carbonization furnace 1 through the feeding mechanism 2, and slowly moves from left to right along the furnace, gradually completing the carbonization process. The combustible pyrolysis gas generated during the carbonization process flows in the opposite direction from right to left along the furnace, and enters the interior of the central heating pipe 3 through the air inlet on the left side of the central heating pipe 3. The pyrolysis gas entering the pipe is ignited and burned by the burner 4. During the combustion process, the pipe wall of the central heating pipe 3 is heated, and the pipe wall then provides heat to the biomass raw material in the furnace through radiation, providing continuous heat for the carbonization of the raw material. The unburned pyrolysis gas in the central heating pipe 3 continues to flow to the right along the pipe body and finally enters the combustion chamber 5 to ensure complete combustion. The carbonized charcoal is discharged from the char outlet at the right end of the carbonization furnace 1, completing the entire carbonization process.

[0023] The internal heating carbonization system based on countercurrent heat exchange using a central heating pipe provided in this application effectively shortens the heat transfer path by setting a central heating pipe 3 that penetrates the furnace and can directly contact the biomass raw materials. This avoids the large amount of heat loss caused by external combustion furnace wall conduction, thus improving heat utilization and carbonization efficiency. Inside the furnace, the biomass raw materials move from left to right and the combustible gas flows from right to left, forming countercurrent heat exchange. Combined with the air inlet hole located near the feed inlet of the central heating pipe 3, the material can receive radiant heat evenly and comprehensively throughout the carbonization process, thereby avoiding local over-carbonization or incomplete carbonization and ensuring the quality of the charcoal. The consistency of the carbonization process is ensured; the combustible pyrolysis gas produced during carbonization is recovered and burned in the central heating tube 3 for heating, and the unburned pyrolysis gas can be further fully burned in the combustion chamber 5, realizing the resource utilization of pyrolysis gas without continuous reliance on external heat sources, which helps to reduce energy consumption costs and ensures clean and safe emissions; the internal heating carbonization system based on countercurrent heat exchange of the central heating tube fundamentally solves the problems of low heat utilization rate, uneven heating of materials, high energy consumption and waste of pyrolysis gas in the existing external combustion carbonization furnace through the coordinated movement of airflow and materials and the in-furnace recovery and utilization of pyrolysis gas, taking into account energy saving, environmental protection and product stability.

[0024] Optionally, the central heating tube 3 is provided with multiple air inlets, which are distributed at intervals along the axial direction of the tube body, and the distribution density of the air inlets is greater the closer they are to the feed inlet.

[0025] Multiple air inlets are spaced apart along the axial direction of the tube. This design addresses the axial non-uniformity of the pyrolysis gas flow, the stability of the airflow organization, and the synergistic requirements of system pressure. It is intended to adapt to the right-to-left flow pattern of combustible pyrolysis gas in the furnace and the core design requirement of counter-current heat exchange in the system, thereby achieving efficient recovery and stable heating of pyrolysis gas.

[0026] Specifically, multiple axially spaced air inlets form a multi-channel pyrolysis gas introduction structure in the area where the central heating pipe 3 is located on the left side of the furnace. This ensures that the combustible pyrolysis gas flowing from right to left is continuously captured at different axial positions as it flows through this area, preventing local accumulation of pyrolysis gas that cannot enter the central heating pipe 3 in time. This ensures a stable flow rate of pyrolysis gas entering the pipe, thereby maintaining the continuity of pipe wall heating during combustion of pyrolysis gas in the pipe. It provides uniform and continuous radiant heat to the biomass raw materials moving from left to right in the furnace, and avoids uneven combustion of pyrolysis gas in the pipe caused by single-point air intake. This prevents local overheating or heat fluctuations in the pipe wall, ensuring uniform heating of the biomass raw materials in the furnace throughout the carbonization process. It effectively avoids local over-carbonization or incomplete carbonization, thereby improving the consistency of charcoal quality.

[0027] In addition, by optimizing the opening ratio of multiple air inlets through axial distribution, a fluid network can be formed with the furnace negative pressure, water seal resistance and the rear induced draft fan to avoid negative pressure imbalance caused by single-point air intake and ensure stable system pressure.

[0028] The design of "the closer to the feed inlet, the greater the distribution density of the air inlets" is because the left side of the furnace where the feed inlet is located is the end area where combustible pyrolysis gas flows from right to left. A denser distribution of air inlets can expand the capture range of pyrolysis gas, improve the recovery efficiency of pyrolysis gas in the end area, and reduce the energy waste caused by the escape of pyrolysis gas. At the same time, a denser distribution of air inlets can allow pyrolysis gas to enter the interior of the central heating tube 3 more evenly.

[0029] Meanwhile, the material at the feed inlet has high humidity and uneven particle state, resulting in large fluctuations in gas production during the pyrolysis reaction start-up phase. The high-density pores can also provide more flexible air intake adjustment space, and by sharing the air intake load through multiple channels, it can adapt to the gas production fluctuations caused by different raw materials (wood chips, straw, etc.) or changes in processing volume, thus making up for the dynamic adaptation defects of the fixed air intake mode.

[0030] In addition, the material accumulation in the furnace on the feed port side is relatively concentrated, and the high-density pores can enhance the local suction capacity. Combined with the furnace negative pressure system, it ensures that the pyrolysis gas is extracted in a timely manner while avoiding local airflow obstruction caused by material accumulation, further ensuring the stability of the carbonization environment. It also forms pressure synergy with the downstream water seal and induced draft fan to maintain the optimal operating state of the system.

[0031] Optionally, the air inlet extends at an angle to guide the incoming airflow to tangentially impact the central region within the central heating tube 3.

[0032] "Inlet port oblique extension" refers to the fact that the air inlet port is not opened vertically along the radial direction of the central heating pipe, nor is it arranged parallel to the axial direction of the pipe body. Instead, it extends obliquely at a preset angle relative to the pipe body axis or the pipe wall normal. Specifically, it can be manifested as a long strip-shaped oblique slot hole opened along the pipe body axis, a circular hole forming an angle of 30-60° with the pipe wall, etc. Some designs can also be equipped with a guide baffle on the inside of the channel to further regulate the airflow direction.

[0033] The inclined air inlet is designed to optimize airflow organization, improve anti-clogging performance, and enhance combustion safety. Specifically, the inclined structure guides the pyrolysis gas tangentially into the central heating tube 3, creating a rotating airflow. This airflow effectively mixes with the flame inside the tube, preventing incomplete combustion or overheating, and also increases the residence time of the pyrolysis gas within the tube, thus improving combustion efficiency. Combined with the baffle, it also prevents the flame from directly exiting the orifice and causing backfire. Furthermore, the inclined channel structure optimizes the fluid flow path, similar to the hydrodynamic effect of a Venturi ejector. This creates a more reasonable pressure gradient within the channel, enhancing the active suction capability of the pyrolysis gas in the furnace and providing better adaptability to negative pressure fluctuations within the furnace. This helps ensure stable recovery of the pyrolysis gas and prevents the system's self-sustaining operation from being affected by airflow deviation.

[0034] Optionally, the inlet hole is tilted in the opposite direction to the rotation direction of the drum-type carbonization furnace. In this way, the inertia of the material rotating with the drum can be used to reduce the accumulation of biomass debris at the orifice, reduce the risk of blockage caused by tar condensation and adhesion, and improve the durability of the orifice.

[0035] Optionally, the air inlet is covered with a filter cover to prevent lumpy materials from entering the central heating tube 3.

[0036] The filter cover is a high-temperature and wear-resistant protective component adapted to the air inlet of the central heating tube 3. It is usually made of high-temperature resistant stainless steel with a mesh or grid structure. The mesh aperture is smaller than the air inlet aperture, which can block the entry of lumpy materials without affecting the flow of pyrolysis gas.

[0037] By using a filter cover to prevent lumpy biomass raw materials and carbonized debris from entering the central heating tube 3 in the furnace, the blockage of the air inlet and the obstruction of the flow guiding structure inside the tube are avoided from the source. At the same time, it can reduce the direct friction between the material and the edge of the air inlet, reduce the wear of the channel, and, together with the inclined extended air inlet structure, further reduce the risk of blockage caused by tar condensation and adhesion, maintain stable pyrolysis gas extraction and combustion conditions inside the tube, and ensure the stability of the system's countercurrent heat exchange and self-sustaining operation.

[0038] Optionally, the filter cover can be fixed to the outside of the furnace side where the air inlet is located by means of snap-on connection, bolt fastening or embedded assembly, and adopts a detachable design to facilitate subsequent cleaning, maintenance or replacement.

[0039] In one embodiment, the burner 4 is used to ignite the pyrolysis gas in the central heating tube 3 in the initial stage. After the system is running stably, the pyrolysis gas in the central heating tube 3 can achieve self-sustaining of the system through self-ignition.

[0040] For details, please refer to Figure 1In the illustrated embodiment, the burner 4 is a low-calorific-value gas burner adapted to the combustion of combustible pyrolysis gas in the central heating tube 3. It is made of high-temperature resistant alloy material, fixedly connected to the left end of the central heating tube 3 through a flange, and equipped with an ignition module, a power adjustment unit and an interface linked with the system controller. It is specifically used for the ignition of pyrolysis gas and the monitoring of the combustion status.

[0041] Specifically, in the initial stage, the burner 4 receives a controller command to start, and the ignition module first ignites the external fuel, preheats the central heating tube 3 and the furnace. After feeding, the biomass raw material is carbonized in the furnace to produce combustible pyrolysis gas, which enters the central heating tube 3 and participates in combustion. As pyrolysis gas is continuously generated, it can gradually replace the external fuel, and finally achieve the self-sustaining nature of the system.

[0042] The system's self-sustainability relies on a closed-loop cycle of "pyrolysis gas combustion - heating - regenerated pyrolysis gas". After the system enters a self-sustaining steady state, the pyrolysis gas spontaneously combusts and releases heat in the central heating tube 3. This heat is then radiated through the tube wall to provide a continuous heat source for the carbonization of biomass raw materials in the furnace. During the carbonization process, new combustible pyrolysis gas is continuously generated. The newly generated pyrolysis gas flows back into the central heating tube 3 and continues to spontaneously combust. Unburned pyrolysis gas is fully combusted in the combustion chamber 5, and the residual heat can further help maintain the system temperature, forming a self-circulating state that does not require a continuous external heat source.

[0043] It needs to be explained that the pyrolysis gas can spontaneously combust because of the synergistic effect of the high-temperature environment formed after the system starts operating and the concentration of the pyrolysis gas. As the burner 4 ignites, the temperature of the central heating tube 3 and the furnace continuously rises until it reaches the auto-ignition point of the pyrolysis gas (approximately 300-500℃). At the same time, the output of the pyrolysis gas continuously increases until its concentration is within the combustible range. Thus, without the need for continuous ignition by the burner 4, combustion can be maintained in the central heating tube 3 by relying on the spontaneous combustion of the pyrolysis gas.

[0044] Achieving system self-sustainability has several advantages. First, it significantly reduces external energy consumption, lowers operating costs, and avoids the waste associated with continuous fuel consumption in traditional equipment. Second, it helps ensure the stability and continuity of system operation. The self-circulation mode adapts to the carbonization rhythm of raw materials, maintaining a dynamic balance between furnace temperature and pyrolysis gas generation. This prevents uneven carbonization caused by fluctuations in external heat sources, ensuring consistent charcoal quality. At the same time, the full recovery and combustion of pyrolysis gas reduces energy waste and environmental risks caused by direct emissions, thus balancing energy efficiency and environmental protection.

[0045] Optionally, the carbonization system also includes a combustion monitoring device, which includes: a first flame detector for monitoring the combustion flame of the burner 4; a second flame detector located in the middle section of the central heating tube 3 or at the inlet side of the combustion chamber 5 for monitoring the combustion flame in the self-sustaining state of the system; and a controller configured to determine the combustion state of the system based on the signals from the first and second flame detectors and to adjust the operating mode of the burner 4 accordingly. The controller is configured to execute a start-up mode, a transition mode, and a monitoring mode. In the start-up mode, the burner 4 is ignited and preheated at a first preset power. In the transition mode, after the second flame detector detects a stable flame, the power of the burner 4 is gradually reduced. In the monitoring mode, the system is in a self-sustaining state, and the burner 4 is maintained at a second preset power in a constant open flame state or an intermittent operating state, where the second preset power is lower than the first preset power.

[0046] Specifically, burner 4 adopts a premixed structure, equipped with a porous ceramic / metal fiber flame stabilizer and a graded adjustable power module. The high-voltage ignition electrode is precisely positioned on the burner head outlet side to ensure stable ignition within the confined space. The combustion monitoring device includes a first flame detector (monitoring the flame of burner 4 itself) and a second flame detector (located in the middle section of the central heating tube 3 or at the inlet of the combustion chamber 5 to confirm the self-sustaining flame of the system), supplemented by a furnace pressure sensor and a combustible gas concentration sensor. The combustion monitoring device also includes an intelligent controller that links the feeding mechanism 2, the emergency purge valve, and the induced draft device (detailed below). It has a built-in "start-transition-monitoring" three-stage program and multi-parameter interlocking logic, forming a complete safety control matrix.

[0047] More specifically, the start-up mode requires the fulfillment of pre-interlock conditions—after the controller detects that the concentration of combustible gas in the central heating tube 3 is within a safe range and the negative pressure in the furnace is normal, it instructs the burner 4 to operate at the first preset high power, forming a rigid and stable flame through a dedicated burner head, quickly preheating the central heating tube 3, creating temperature conditions for the spontaneous combustion of pyrolysis gas, solving the ignition problem of unstable gas source and limited space in the tube during cold start-up, and efficiently completing system preheating.

[0048] The transition mode is triggered by the signal feedback of the second flame detector. When the pyrolysis gas in the central heating tube 3 is detected to have been successfully ignited and formed a stable flame, the intelligent controller determines that the system has entered the self-sustaining transition stage, gradually reduces the power of the burner 4, avoids mutual interference between the main combustion and the self-sustaining flame, and continuously verifies the combustion status through dual detectors to achieve a smooth transition from "external ignition" to "self-sustaining".

[0049] The monitoring mode is activated on the premise that the system maintains stable combustion (continuously confirmed by the second flame detector). The controller instructs burner 4 to switch to the second preset low-power or periodic pulse operation state, becoming a "safe flame". At this time, if the raw material fluctuation causes the self-maintaining flame to be unstable, the burner can instantly increase the power to achieve "self-healing". If the loss of the self-maintaining flame is detected, the power is first increased to attempt to restore it and an alarm is triggered. If the flame of burner 4 itself is also extinguished, the feeding mechanism is immediately interlocked and shut down, the emergency purge valve is opened to inject purge medium, and the emergency shutdown procedure is initiated. The purpose of this mode is to balance the low energy consumption of the system in steady-state operation with the safety redundancy under abnormal operating conditions, avoid the risk of combustible gas accumulation or backfire, and ensure the continuity and safety of the system's self-circulation.

[0050] Optionally, the combustion monitoring device also includes an emergency purge valve, which is located on the central heating tube 3; the controller is interlocked with the feeding mechanism 2 and the emergency purge valve; when both the first flame detector and the second flame detector detect flameout, the controller executes an emergency shutdown procedure, including closing the feeding mechanism 2 and opening the emergency purge valve to inject purge medium into the central heating tube 3.

[0051] The emergency purge valve is a normally closed, fast-acting valve adapted to the safety protection requirements of the central heating tube 3. Specifically, it is a solenoid valve or pneumatic valve made of high-temperature and corrosion-resistant materials. It is installed between the burner interface on the left end of the central heating tube 3 and the first air inlet. In some scenarios, a supplementary purge valve can be added at the inlet of the combustion chamber 5 or on the side wall of the furnace. The valve is equipped with an upstream gas storage tank, pressure reducing valve, flow meter, check valve and manual shut-off valve. It is connected to the central heating tube through an annular distribution pipe or a multi-hole nozzle to ensure that the purge medium is injected evenly in the circumference.

[0052] The use of the emergency purge valve must strictly follow the interlock control logic. The controller will only immediately trigger the emergency shutdown procedure when both the first and second flame detectors detect flameout. The emergency purge valve will open synchronously (or with a delay of less than 1 second), simultaneously shutting down burner 4, feeding mechanism 2, and related process valves. In some scenarios, the rotation of carbonization furnace 1 can be stopped. The purge medium is selected from inert gases such as nitrogen and carbon dioxide or saturated steam (compressed air is the second choice, subject to explosion risk assessment). It is injected at a stable pressure of 0.2-0.5 MPa and purges continuously for at least 30 seconds (ensuring a replacement rate greater than 3 times the internal volume of the pipe). After purging, the valve can automatically close or remain open, and the system will be locked in a shutdown state. The operator must confirm safety on-site and manually reset the system using a dedicated reset button before restarting the system.

[0053] The addition of an emergency shutdown procedure addresses the safety hazard of combustible gas accumulation in the central heating tube 3 and furnace after double flameout. By rapidly injecting an inert medium, residual combustible pyrolysis gas in the central heating tube 3, air inlet, and part of the furnace space is efficiently replaced, preventing the gas from reaching explosive concentrations. Simultaneously, it blocks the path of flame backflow to the burner 4 gas supply line or furnace, preventing backfire and explosion accidents. Stable purging pressure and uniform injection ensure thorough replacement, protecting core components such as the central heating tube 3 and combustion chamber 5 from damage by residual gas combustion. This provides a safe environment for operators to troubleshoot on-site, compensating for the lack of active protection in simple flameout alarms and establishing system safety redundancy.

[0054] Optionally, a water seal device 6 is provided on the section of the central heating pipe 3 located between the carbonization furnace 1 and the combustion chamber 5. The water seal device 6 is used to regulate the system pressure, provide a safe seal and prevent backfire. The water seal device 6 is equipped with a liquid level sensor and a regulating valve. The liquid level sensor is used to monitor the height of the liquid seal, and the regulating valve is connected to the liquid level sensor signal to maintain a constant height of the liquid seal.

[0055] For details, please refer to Figure 1 In the illustrated embodiment, the water seal device 6 is an insert-type water seal tank adapted for pressure regulation and safety protection between the central heating pipe 3 and the combustion chamber 5. It is a vertical cylindrical sealed structure made of corrosion-resistant and high-temperature-resistant stainless steel, including an air inlet pipe (an extension of the central heating pipe 3) extending below the liquid surface inside the tank, an air outlet pipe connecting the top of the tank to the combustion chamber 5, a side water level gauge / sight glass, an upper water inlet and overflow outlet, a bottom conical slag collection hopper and drain valve, and a top maintenance manhole. It is also equipped with a liquid level sensor and a regulating valve. The water seal device 6 is fixed to the ground or base by a bracket, providing both physical protection and automatic control functions.

[0056] During installation, first disconnect the right end of the central heating pipe 3, and connect it to the air inlet pipe at the top of the water seal tank through a horizontal transition pipe, so that the air inlet pipe is inserted into the tank 100-200mm from the bottom (below the design water level line); connect the air outlet pipe at the top of the tank to the air inlet of the combustion chamber 5. During operation, clean water is added through the water inlet, and the water level is observed in real time with the help of the water level gauge / sight glass. The liquid level sensor and the regulating valve are linked to automatically maintain a constant liquid seal height of 100-250mm (adapting to the operating pressure difference required by the system). In cold environments, the tank and pipelines need to be insulated or equipped with a heating device to prevent freezing. In daily life, wastewater containing tar and impurities needs to be discharged regularly through the bottom drain valve, and internal cleaning and maintenance should be carried out through the maintenance manhole. In case of overpressure, secondary pressure relief protection is achieved by relying on the explosion-proof plate or safety valve on the tank.

[0057] The liquid level sensor and the regulating valve work together to maintain a constant liquid seal height within the water seal device 6, ensuring the stable operation of the water seal device 6 in regulating system pressure, providing a safe seal, and preventing backfire. During operation, the liquid level sensor monitors the actual liquid seal height within the water seal device in real time and converts the monitored liquid level data into an electrical signal, which is transmitted to the regulating valve with which it has a signal connection. When the monitored liquid seal height is lower than a preset constant value, the regulating valve receives the signal and opens or increases its opening to replenish liquid into the water seal device until the liquid seal height rises back to the preset value. When the monitored liquid seal height is higher than the preset constant value, the regulating valve receives the signal and closes or decreases its opening to stop replenishing liquid, thereby precisely maintaining the liquid seal height within the preset constant range. This ensures that the water seal device 6 always possesses reliable sealing performance, pressure regulation capability, and backfire prevention effect.

[0058] The water seal device 6 achieves sealing and pressure regulation, forming a stable pressure difference through a constant liquid seal to ensure a stable micro-negative pressure environment within the carbonization furnace 1. This ensures that the pyrolysis gas is smoothly drawn into the central heating pipe 3 and flows into the combustion chamber 5. Combined with the induced draft device, it achieves precise system pressure balance. The water seal device 6 also provides safety flame arrest, acting as a physical barrier to prevent the flame or high-temperature airflow in the combustion chamber 5 from backfireing into the central heating pipe 3 and the carbonization furnace 1, fundamentally avoiding the risk of combustible gas deflagration. The water seal device 6 also has a condensation and purification function. When the high-temperature pyrolysis gas passes through the water, some tar and water are cooled and condensed in the water, thus initially purifying the gas and reducing subsequent coking in the combustion chamber 5. The sight glass allows for direct observation of airflow conditions and system resistance, and the bottom drainage and maintenance structure facilitates regular cleaning of impurities, ensuring long-term stable operation of the device. The water seal device 6 is a key component for system pressure regulation, safety protection, and preliminary gas purification.

[0059] Optionally, the carbonization furnace 1 is equipped with a pressure sensor to monitor the gas pressure inside the furnace; an induced draft device is provided on the gas exhaust path of the carbonization furnace 1, and the working power of the induced draft device is adjusted according to the detection signal of the pressure sensor, so as to control the negative pressure atmosphere inside the carbonization furnace 1.

[0060] The pressure sensor is a high-precision detection component used for real-time monitoring of the gas pressure inside the carbonization furnace 1. It typically employs temperature-resistant and dust-resistant differential pressure or absolute pressure sensors, installed on the side wall at the end of the furnace, avoiding direct impact from materials. The pressure sensor's signal is connected to the system controller, enabling accurate capture of gas pressure fluctuations inside the furnace (the measurement range is adapted to micro-negative pressure requirements from -500Pa to 500Pa).

[0061] The induced draft device is a centrifugal or axial flow fan equipped with a frequency conversion adjustment module, installed at the rear end of the gas emission path of carbonization furnace 1 (such as between the waste heat boiler and the chimney), and linked with the controller signal. The extraction rate can be changed by adjusting the working power.

[0062] Specifically, the pressure sensor continuously transmits the actual gas pressure signal inside the furnace to the controller. The controller compares it with the preset target negative pressure value. If the negative pressure inside the furnace is lower than the set value (i.e., the gas pressure is too high), the power of the induced draft device is increased to enhance the suction force; if the negative pressure is higher than the set value (i.e., the gas pressure is too low), the power of the induced draft device is reduced to weaken the suction force. The entire process is automatically and dynamically adjusted without manual intervention.

[0063] By precisely maintaining a slightly negative pressure atmosphere inside the furnace, it is possible to prevent the leakage of combustible pyrolysis gas in the furnace, which could lead to energy waste or safety hazards. On the other hand, it is also possible to prevent air from seeping in and affecting the carbonization environment (leading to material oxidation or incomplete combustion). At the same time, it provides a stable pressure driving force for the pyrolysis gas to flow smoothly from right to left and enter the central heating tube 3 and combustion chamber 5, ensuring the efficiency of countercurrent heat exchange and pyrolysis gas recovery.

[0064] Furthermore, the pressure sensor, induced draft fan, and water seal device 6 constitute a collaborative pressure control system of "baseline setting - real-time monitoring - dynamic fine-tuning". The water seal device 6 maintains a constant liquid seal height through a level sensor and regulating valve, providing a stable baseline resistance for the system, acting as a "baseline anchor" for pressure control and preventing pressure runaway due to system resistance fluctuations. The pressure sensor, as a "monitoring terminal", accurately feeds back error signals deviating from the target value by capturing real-time changes in gas pressure within the furnace; the induced draft fan, as an "actuator", performs fine-tuned power adjustment based on the feedback signal from the pressure sensor, using the stable resistance baseline provided by the water seal device 6, to compensate for gas pressure fluctuations caused by changes in raw material characteristics and gas production rate.

[0065] Specifically, the water seal device 6 first establishes a basic pressure difference in the system through a constant liquid seal to ensure the stability of the pyrolysis gas flow path; the pressure sensor continuously monitors the furnace gas pressure and transmits the deviation signal to the controller; the controller drives the induced draft device to adjust the suction force, dynamically balancing the system gas flow rate above the basic resistance, so that the furnace gas pressure is always stable within the target negative pressure range.

[0066] This collaborative mode enables higher pressure control precision, avoids drastic pressure fluctuations caused by single adjustment methods, ensures the stability of pyrolysis gas recovery and combustion, provides a foundation for the system's self-sustaining operation, and effectively isolates the pressure influence between combustion chamber 5 and carbonization furnace 1. The physical barrier of water seal device 6, combined with the suction adjustment of the induced draft device, can prevent backfire caused by a sudden increase in pressure in combustion chamber 5, and avoid excessive furnace negative pressure caused by excessive induced draft, thus helping to improve system safety. In addition, it can adapt to different operating conditions. The combination of stable resistance of water seal and dynamic adjustment of induced draft can cope with gas production fluctuations caused by changes in raw material type and processing volume, ensuring that the furnace negative pressure is always in the optimal range, thereby ensuring the uniformity of material carbonization and heat utilization rate.

[0067] In one embodiment, the carbonization furnace 1 is a drum-type carbonization furnace. The carbonization furnace 1 is equipped with a rotary drive device 10, which is used to drive the carbonization furnace 1 to rotate at a uniform speed and can adjust the rotation speed of the carbonization furnace 1 according to the state of the raw materials or the process stage. The central heating pipe 3 is fixedly installed and does not rotate with the carbonization furnace 1. The central axis of the central heating pipe 3 coincides with the axis of the drum of the carbonization furnace 1. When the carbonization furnace 1 rotates, the material in the furnace can fully contact the central heating pipe 3.

[0068] For details, please refer to Figure 1 In the illustrated embodiment, the rotary drive device 10 is a variable frequency speed control drive mechanism adapted to a drum-type carbonization furnace. Its core consists of a variable frequency motor and a reducer, which cooperate with the rolling ring 12 of the carbonization furnace 1 through a transmission structure to drive the carbonization furnace 1 to rotate at a uniform speed. The rotary drive device 10 relies on variable frequency control, enabling flexible start-up and stepless speed regulation. During start-up, the speed can be gradually increased to avoid impact on the transmission and support structures. During operation, the speed can be dynamically adjusted according to the raw material condition and process stage.

[0069] The specific adjustment method can be flexibly adapted to actual needs. For example, when processing biomass raw materials with high moisture content (more than 30%), the rotation speed can be adjusted to 0.5-0.8 r / min to extend the preheating time of the raw materials in the furnace, ensure that the moisture evaporates fully, and avoid the sticking of wet materials that affects the carbonization effect. When processing wood chips with fine particle size (particle size less than 5 mm), the rotation speed can be adjusted to 1.0-1.2 r / min to ensure that the raw materials are turned over evenly and to prevent dust or local accumulation caused by excessive rotation speed. When processing fruit shell raw materials with high density (bulk density exceeding 0.6 g / cm³), the rotation speed can be increased to 1.5-2.0 r / min to enhance the collision and contact between the raw materials and the central heating tube 3.

[0070] The central heating tube 3 is fixed and does not rotate with the carbonization furnace 1. The central axis of the central heating tube 3 is completely aligned with the axis of the drum of the carbonization furnace 1, so that the central heating tube 3 is located in the center of the furnace. In this way, when the carbonization furnace 1 rotates, the material in the furnace is continuously turned, lifted and scattered under the action of gravity and friction of the inner wall of the drum. The central arrangement of the central heating tube 3 ensures that the material can fully collide and contact the tube surface during the turning process, regardless of its position in the furnace, avoiding dead corners. Combined with the dynamic effect of the drum rotation, it can achieve full and uniform contact between the material and the central heating tube 3, ensuring the efficiency of radiative heat exchange.

[0071] Optionally, the rotary drive 10 includes at least two independent drive units to ensure torque balance through electrical synchronization control, thereby preventing torsional deformation of the carbonization furnace 1.

[0072] The drive unit is the core actuator of the rotary drive device 10. It consists of a variable frequency motor and a matching reducer. Each drive unit is driven by a gear meshing with a gear ring (set in the form of an external gear) on the outer wall of the carbonization furnace 1. It is specially adapted to the drive requirements of large long drums to ensure stable power transmission.

[0073] Specifically, the two independent drive units operate in coordination through a "master-slave electrical synchronous control" system. One drive unit is the active drive unit, and the other is the driven drive unit. These two independent drive units are located at opposite ends of the length of the carbonization furnace 1. The active unit receives speed commands from the system controller and outputs a set speed and torque. The driven unit tracks the active unit's operating parameters (such as speed, torque, and current) in real time through a signal acquisition module and dynamically adjusts its own output under the controller's control to ensure that the speeds of the two units remain consistent. Simultaneously, the controller incorporates a torque balancing algorithm that continuously monitors the output torque difference between the two drive units. When the difference exceeds a preset threshold, the controller automatically adjusts the power of the driven unit's variable frequency motor to compensate for the torque deviation, ensuring that both units apply a uniform driving force to the carbonization furnace 1.

[0074] This configuration eliminates the power lag or force concentration problems that may occur with single-point drive through electrical synchronization, making the rotation of large long drums more stable and effectively avoiding torsional deformation of the drum body caused by uneven force at both ends or different parts.

[0075] Optionally, the carbonization furnace 1 is rotatably mounted on a base, the base including at least two pairs of support rollers 11, and the carbonization furnace 1 is provided with at least two sets of rolling rings 12, the carbonization furnace 1 being rotatably supported on the support rollers 11 by the rolling rings 12.

[0076] The support roller 11 is a load-bearing component adapted to the support requirements of the drum-type carbonization furnace. It is made of high temperature resistant and wear-resistant material. Each set of support rollers 11 is rotatably mounted on the base bracket through bearings, and the whole is arranged in a V-shaped symmetrical arrangement.

[0077] The rolling ring 12 is a ring structure that is fixedly sleeved on the outer wall of both ends of the drum of the carbonization furnace 1. It is made of high-strength alloy material and is set coaxially with the drum. It serves as the core force support point of the carbonization furnace 1 and is precisely matched with the wheel surface of the support roller 11.

[0078] When the two are used together, the carbonization furnace 1 sits stably on the support rollers 11 of the base through the rolling rings 12 at both ends. The outer circumferential surface of the rolling rings 12 is in close contact with the wheel surface of the support rollers 11 to form a rolling friction fit. When the rotary drive device 10 drives the carbonization furnace 1 to run, the rolling rings 12 rotate synchronously with the drum, thereby driving the support rollers 11 to rotate passively around their own central axis. This not only ensures the stability of the carbonization furnace rotation, but also greatly reduces the running resistance.

[0079] The matching support rollers 11 and rolling rings 12 serve two purposes: firstly, they provide strong load-bearing capacity, stably supporting the heavy-duty, long drum-type carbonization furnace, and are adapted to the overall weight and operating load of the equipment; secondly, the rolling friction fit structure is simple, reliable, and easy to maintain, effectively avoiding the shortcomings of traditional large bearings such as insufficient load-bearing capacity and susceptibility to high-temperature failure, thus contributing to the long-term and stable operation of the carbonization system. Furthermore, the V-shaped arrangement of the support rollers 11 automatically corrects the radial offset of the drum during the rotation of the carbonization furnace, ensuring that the central axis of the central heating tube 3 always coincides with the drum axis, guaranteeing sufficient contact between the material and the central heating tube.

[0080] Optionally, the carbonization furnace 1 is rotatably mounted on a base, which is provided with an adaptive self-aligning structure to compensate for the deformation of the carbonization furnace 1 caused by heating.

[0081] In one embodiment, the adaptive self-aligning structure is a spherical pad type adaptive self-aligning structure, specifically consisting of a paired upper spherical pad and a lower spherical pad. The lower surface of the upper spherical pad is a convex spherical surface, and the upper surface of the lower spherical pad is a matching concave spherical surface. The two are constrained by a central pin to prevent horizontal misalignment, and the contact surfaces are coated with high-temperature grease to reduce friction.

[0082] During installation, the top plane of the upper spherical pad is fixedly connected to the bottom of the roller bearing seat, and the bottom plane of the lower spherical pad is fastened to the base plate of the base, forming the intermediate self-adaptive layer of the roller support.

[0083] During use, when the carbonization furnace 1 experiences thermal bending due to uneven heating at both ends of the furnace chamber, gravity-induced sag due to the weight of the long drum itself and the material, or slight uneven settlement of the equipment foundation, the deformation will cause the rolling ring 12 of the carbonization furnace 1 to shift synchronously, thereby generating a tilting torque on the support roller 11. After this torque is transmitted to the support roller bearing seat, it will force the upper spherical pad to slide and rotate slightly along the concave spherical surface of the lower spherical pad, causing the entire support roller assembly to deflect at an angle that matches the bending direction of the cylinder, so that the axis of the support roller always maintains full-width parallel contact with the axis of the rolling ring.

[0084] Adding an adaptive self-aligning structure can avoid the problem of edge contact between the rolling ring 12 and the support roller 11 caused by the "locking" deformation of the rigid support, thereby reducing local stress concentration and abnormal wear, preventing drive power overload, reducing vibration and noise during equipment operation, eliminating jamming failures caused by deformation, ensuring the long-term and stable operation of the carbonization furnace 1, and extending the service life of key support components such as the rolling ring 12 and the support roller 11.

[0085] In another embodiment, the adaptive self-aligning structure is a double-row self-aligning roller bearing, whose outer ring raceway is designed as a spherical surface with the bearing center as the center. The inner ring, rolling elements, and cage can achieve a preset angle of deflection within the spherical surface range. The double-row self-aligning roller bearing replaces the traditional rigid bearing and is directly installed in the bearing housing at both ends of the support roller 11 as the support bearing for the roller 11.

[0086] When the cylinder of the carbonization furnace 1 undergoes slight bending due to thermal deformation or gravity, the rolling ring 12 applies an tilting force to the support roller 11. After this force is transmitted to the support roller shaft, the inner ring and rolling elements of the self-aligning roller bearing can automatically adapt to the deflection along the outer ring spherical raceway, causing the support roller shaft to make slight angle adjustments following the bending trend of the cylinder, ensuring that the wheel surface of the support roller 11 and the rolling ring 12 always maintain uniform contact.

[0087] Using double-row self-aligning roller bearings, the bearings can achieve self-alignment through their own structural characteristics, eliminating the need for additional complex mechanical structures. This makes installation and maintenance more convenient. The bearings can effectively compensate for the deflection angle of the cylinder during operation, avoiding increased wear and drive overload caused by uneven local stress. They are also suitable for the high-temperature working environment of the carbonization furnace, ensuring the reliability of the equipment under deformation conditions. They are especially suitable for scenarios with certain limitations on installation space.

[0088] Optionally, the carbonization system also includes a speed monitoring sensor to trigger a safety interlock action when the speed is abnormal.

[0089] The rotation speed monitoring sensor is a non-contact detection component adapted for the safe monitoring of the rotation speed of a drum-type carbonization furnace. Specifically, it is a proximity switch with high temperature resistance and dust interference resistance. It is installed on the outside of the rolling ring 12 of the carbonization furnace 1 or near the transmission component of the rotary drive device 10. It is connected to the system controller signal and can accurately collect the rotation frequency of the carbonization furnace 1 and convert it into an electrical signal.

[0090] Specifically, the speed monitoring sensor continuously monitors the real-time speed of the carbonization furnace 1 in a non-contact manner and transmits the signal to the controller in real time. The controller has a built-in preset normal speed range. When it detects that the drum stops rotating, the speed is lower than the lower limit or higher than the upper limit (such as abnormal high speed caused by slippage), it immediately triggers the safety interlock action, automatically starts the alarm device, and at the same time cuts off the operation of the feeding mechanism 2 or adjusts the power of the burner 4 to avoid the dangerous working condition from continuing.

[0091] Adding a speed monitoring sensor can ensure the safe operation of the system and the stability of the equipment. By timely detecting abnormal speed, it can prevent local overheating, heat accumulation, or even fire caused by the material in the furnace being stationary or flowing abnormally when the drum stops or the speed is unbalanced, so as to avoid the risk of fire. At the same time, it can avoid overload of drive components, uneven carbonization of materials, or mechanical damage to equipment caused by abnormal speed, reduce the incidence of equipment accidents, and provide safety redundancy for the continuous and stable operation of the carbonization system.

[0092] Optionally, the inner wall of the carbonization furnace 1 is provided with a plurality of axially extending lifting plates, which are used to lift and scatter materials during the rotation of the carbonization furnace 1.

[0093] Lifting plates are material turning and guiding components adapted to drum-type carbonization furnaces. They are made of high-temperature resistant and wear-resistant alloy plates and can be straight, L-shaped, or fan-shaped, extending along the length of the carbonization furnace. The lifting plates can be fixed to the inner wall of the drum by welding, bolting, or other methods to withstand the impact of material turning.

[0094] During use, as the carbonization furnace 1 rotates at a constant speed under the drive of the rotary drive device 10, the lifting plate rotates synchronously with the drum, continuously lifting the biomass raw material at the bottom of the drum to a certain height. When the raw material exceeds the bearing capacity of the lifting plate, it will be evenly thrown down under the action of gravity, forming a continuous "material curtain".

[0095] This increases the contact area between the material and the radiant heat of the central heating pipe 3, as well as the hot airflow inside the furnace, enhancing heat and mass transfer efficiency and preventing material from accumulating mainly at the bottom of the drum, which would lead to uneven heating. At the same time, the formation of the material curtain allows each piece of material to fully receive heat, effectively solving the problem of incomplete or excessive carbonization in certain areas and ensuring the consistency of charcoal quality.

[0096] Optionally, the installation direction of the lifting plate is set at an angle to the axis of the carbonization furnace 1, so that the material can be fed downstream while being thrown.

[0097] Specifically, the lifting plate is not along the axial direction of carbonization furnace 1 (i.e., Figure 1 Instead of the material being fed in parallel from left to right, the lifting plates are arranged at a preset tilt angle to form an angle with the axial direction, so that the lifting plates present a spiral distribution trend. Essentially, through a specific spiral tilt angle design, the lifting plates can both lift and scatter the material and generate a directional axial driving force when rotating with the drum.

[0098] In industrial applications, this included angle is usually set to 15-30 degrees. This angle range is the optimal range for balancing axial thrust and material throwing effect (if the angle is too small, the axial driving force is insufficient, and the material is easy to stay in the furnace and cannot be fed in time; if the angle is too large, the material is not thrown enough, the contact efficiency with the central heating tube 3 decreases, and the carbonization may be incomplete due to feeding too fast).

[0099] The angled arrangement allows the lifting plates to rotate with the carbonization furnace 1, lifting and scattering the material to form a material curtain. At the same time, the tilt angle generates a continuous and constant axial thrust, which pushes the material steadily from left to right along the furnace towards the carbon discharge port. This allows for precise control of the material's residence time in the furnace, ensuring that each piece of material is fully carbonized. It also avoids the shortcomings of simple axial parallel lifting plates, which can only scatter the material and cannot actively control the feeding rhythm. This solves the problems of accumulation and uneven feeding that easily occur when the material is fed by its own gravity or by the tilting of the roller.

[0100] Optionally, the shape, density, or installation angle of the scraper plates can be differentiated according to the temperature and functional zones within the carbonization furnace 1.

[0101] For details, please refer to Figure 1 In the illustrated embodiment, based on the material's movement path from left to right, the temperature gradient within the furnace, and the process stages (preheating and drying → pyrolysis and carbonization → high-temperature refining), the carbonization furnace 1 is divided into three functionally distinct zones: a preheating section (adjacent to the feeding mechanism 2, located at the material inlet, its core task being to quickly dry the moisture in the biomass raw materials and preliminarily decompose volatile components), a dry distillation section (located in the middle of the furnace, where the temperature is most stable, its core task being to allow the material to remain sufficiently at the target carbonization temperature, achieving full volatile matter release and the conversion of biomass into charcoal, which is a key area determining charcoal quality), and a charcoal discharge section (away from the ignition area, located at the charcoal discharge port).

[0102] To enhance the functionality of the lifting plates, their design can be differentiated to meet the process requirements of each zone. Specifically, the left section (preheating section) uses L-shaped or large-volume lifting plates, distributed at a medium to high density along the circumference of the furnace, with an installation angle of 40°-55°. This allows for rapid passage of wet material through a large axial thrust, preventing accumulation, while the large volume structure and high-frequency turning create a thick material curtain, fully utilizing the hot airflow within the area for efficient drying and heat exchange. The middle section (dry distillation section) uses straight or folded durable lifting plates, arranged at a medium density with a small installation angle of 0°-20°. This reduces axial thrust, extending the residence time of the material in the core carbonization temperature range, ensuring sufficient volatile matter release, while gentle turning reduces mechanical breakage of already carbonized particles. The right section (charcoal discharge section) uses straight plates or short lifting plates with a low density distribution and a medium installation angle of 20°-35°. This allows the basically carbonized material to pass through at a reasonable speed, avoiding the burning of fixed carbon. The low turning frequency can protect the quality of charcoal and reduce dust generation, which is suitable for the characteristics of this area where heat transfer is mainly radiation and convection.

[0103] This zoned differentiated design allows the lifting plates to precisely match the temperature environment and process objectives of each zone while rotating and scattering materials along with the carbonization furnace 1 to form a material curtain and increase the contact area between the material and the heat flow. This not only helps to ensure heat and mass transfer efficiency, but also allows for flexible control of material feeding speed and residence time. It effectively solves the problems of uneven carbonization, excessive crushing, or inappropriate residence time, and helps to ensure continuous and stable operation of the system and ensure the consistency of charcoal quality.

[0104] Optionally, the feed inlet and / or discharge outlet are provided with: a fixed cover 7, the end of the carbonization furnace 1 being rotatably disposed within the fixed cover 7; a dynamic sealing mechanism, disposed between the fixed cover 7 and the carbonization furnace 1, including a labyrinth seal and a flexible contact seal arranged sequentially along the gas leakage direction; the labyrinth seal includes: at least one set of labyrinth moving rings 21, disposed on the outer wall of the end of the carbonization furnace 1, capable of rotating synchronously with the carbonization furnace 1; at least one set of labyrinth stationary rings 22, disposed on the inner wall of the fixed cover 7, the labyrinth stationary rings... The 22 and labyrinth ring 21 are distributed alternately and at intervals along the axial direction, and together they form a tortuous flow channel; the flexible contact sealing part includes: a sealing ring 23, which is sleeved on the end of the carbonization furnace 1 and is pressed between the carbonization furnace 1 and the fixed cover 7; a floating pressure cover 24, which is located on the side of the sealing ring 23 facing away from the labyrinth sealing part; and an elastic force application unit 25, which is pressed between the floating pressure cover 24 and the fixed cover 7, and is used to provide axial pressure to the floating pressure cover 24 so that the sealing ring 23 presses the carbonization furnace 1 and the fixed cover 7.

[0105] For details, please refer to Figure 2 In the illustrated embodiment, a fixed cover 7 is provided at the end of the carbonization furnace 1. The fixed cover 7 is rotatably connected to the carbonization furnace 1 through a bearing. The central heating pipe 3 passes through the fixed cover 7. The fixed cover 7 can both seal the end of the carbonization furnace 1 and support the central heating pipe 3.

[0106] Continue to refer to Figure 2 The labyrinth seal, as the main flow-blocking component of the dynamic sealing mechanism, consists of at least one labyrinth moving ring 21 and one labyrinth stationary ring 22 (the figure shows three labyrinth moving rings 21 and two labyrinth stationary rings 22, which are arranged alternately; the more rings, the more winding the labyrinth path). The labyrinth moving ring 21 is fixed to the outer wall of the end of the carbonization furnace 1 and can rotate synchronously with the carbonization furnace 1; the labyrinth stationary ring 22 is installed on the inner wall of the fixed cover 7, and is distributed alternately and at intervals with the labyrinth moving ring 21 along the axial direction. Together, they form a series of axially arranged annular cavities and narrow radial gaps alternating tortuous flow channels, and adopt a non-contact design, with reserved small gaps to accommodate the thermal deformation and dynamic jump of the carbonization furnace 1.

[0107] Continue to refer to Figure 2The flexible contact seal, serving as the final sealing barrier, is located on the outside of the labyrinth seal (away from the furnace end) and includes a flexible sealing ring 23, a floating pressure cap 24, and an elastic force application unit 25. The flexible sealing ring 23 is a complete annular component made of multiple layers of high-temperature resistant flexible materials (such as reinforced graphite composite plates). Its inner diameter is slightly smaller than the outer diameter of the sealing sleeve at the end of the carbonization furnace 1. It is fitted onto the carbonization furnace 1 and pressed between the inner wall of the fixed cover 7 and the outer wall of the carbonization furnace 1, forming an interference fit. The floating pressure cap 24 is an annular structure located on the outside of the flexible sealing ring 23 away from the labyrinth seal and fixed to the inner wall of the fixed cover 7. The elastic force application unit 25 consists of multiple high-temperature resistant springs (or sheet springs or block structures made of other materials) evenly distributed circumferentially. It is pressed between the floating pressure cap 24 and the flexible sealing ring 23, providing continuous axial pressure.

[0108] The labyrinth seal maximizes leakage path resistance through its tortuous flow channels, achieving primary flow obstruction. When gas inside the furnace attempts to leak out or outside air attempts to infiltrate, it must repeatedly pass through annular cavities and narrow gaps. Each time it passes through an annular gap, pressure and flow velocity decrease significantly due to throttling and expansion. After passing through multiple annulus gaps, most of the gas pressure differential is consumed, greatly suppressing leakage. Simultaneously, the labyrinth seal's non-contact design makes it resistant to the high-temperature environment at the end of the carbonization furnace and adaptable to changes in the length and diameter of the cylinder after heating, eliminating wear risks and ensuring long-term operational stability. This lays the physical foundation for maintaining a precise atmosphere inside the furnace (combustible pyrolysis gas concentration and oxygen content).

[0109] The flexible contact seal is used to block trace amounts of gas that pass through the labyrinth seal, forming a final sealing barrier. Figure 2 In the illustrated embodiment, the preload of the elastic force-applying unit 25 pushes the flexible sealing ring 23 tightly against the last labyrinth moving ring 21 through the floating pressure cap 24, forming a reliable seal. During operation, the flexible nature of the elastic force-applying unit 25 can tolerate minute radial and axial displacements of the cylinder caused by thermal expansion and contraction, manufacturing errors, or rotational runout. The elastic force-applying unit 25 can dynamically compress or release with the displacement, causing the floating pressure cap 24 and the sealing ring 23 to move synchronously and maintain a close fit, avoiding the formation of new gaps.

[0110] The labyrinth seal and the flexible contact seal work together to form a dual sealing system that combines rigidity and flexibility. On the one hand, the dynamic sealing mechanism has reliable sealing performance. It significantly reduces gas leakage dynamics through the labyrinth seal and blocks trace residual leakage through the flexible contact seal. This effectively prevents the infiltration of external air (avoiding dilution of pyrolysis gas and disruption of internal combustion balance) and the leakage of combustible gas from the furnace (reducing energy waste and pollution), ensuring a slightly negative pressure atmosphere and a stable reaction atmosphere inside the carbonization furnace 1, providing a core guarantee for the system's self-circulating operation. On the other hand, the dynamic sealing mechanism has extremely strong adaptability to operating conditions. The non-contact design of the labyrinth seal is resistant to high temperatures and thermal deformation, while the floating structure of the flexible contact seal adapts to the dynamic movement of the cylinder. Together, they can cope with multiple complex operating conditions during continuous operation of the carbonization furnace and avoid seal failure. In addition, the dynamic sealing mechanism has high mechanical reliability. The non-contact labyrinth seal is wear-free, and the automatic wear compensation function of the flexible seal can extend the life of the sealing components. Together, they can effectively ensure continuous and stable operation of the equipment.

[0111] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An internal heating carbonization system based on countercurrent heat exchange through a central heating tube, characterized in that, include: Carbonization furnace (1), the furnace chamber of the carbonization furnace (1) extends in a straight line, with a feed port at the left end and a carbon discharge port at the right end; The feeding mechanism (2) is connected to the feed inlet and is used to transport biomass raw materials into the carbonization furnace (1); A central heating tube (3) is installed inside the furnace. Its left end is connected to a burner (4) located outside the furnace, and its right end is connected to a combustion chamber (5) located outside the furnace. An air inlet is provided on the central heating tube (3), and the air inlet is located on the left side of the furnace near the feed inlet. During operation, the biomass raw materials move from left to right in the furnace and complete carbonization. The generated charcoal is discharged through the charcoal outlet, while the generated combustible thermal decomposition gas flows from right to left in the furnace and enters the central heating pipe (3) through the air inlet. The pyrolysis gas is burned in the central heating tube (3), and after heating the tube wall, it supplies heat to the furnace by radiation. Unburned pyrolysis gas can enter the combustion chamber (5) along the central heating tube (3) and be fully burned in the combustion chamber (5).

2. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 1, characterized in that, The central heating tube (3) is provided with multiple air inlets, which are distributed at intervals along the axial direction of the tube body. The closer to the feed inlet, the greater the distribution density of the air inlets. And / or, the air inlet extends obliquely to guide the incoming airflow to tangentially impact the central region within the central heating tube (3); And / or, the air inlet is covered with a filter cover to prevent lumpy materials from entering the central heating tube (3).

3. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 1, characterized in that, The burner (4) is used to ignite the pyrolysis gas in the central heating tube (3) in the initial stage. After the system is running stably, the pyrolysis gas in the central heating tube (3) can achieve the self-sustaining of the system through self-ignition. The carbonization system further includes a combustion monitoring device, which includes: A first flame detector is used to monitor the combustion flame of the burner (4); The second flame detector is located in the middle section of the central heating tube (3) or at the entrance of the combustion chamber (5) to monitor the combustion flame in the self-sustaining state of the system. The controller is configured to determine the combustion state of the system based on the signals from the first flame detector and the second flame detector, and to adjust the operating mode of the burner (4) accordingly. The controller is configured to perform startup mode, transition mode, and monitor mode; In the start-up mode, the burner (4) is ignited and the central heating tube (3) is preheated at a first preset power. In the transition mode, after the second flame detector detects a stable flame, it gradually reduces the power of the burner (4); In the monitoring mode, the system is in a self-sustaining state, which enables the burner (4) to maintain a constant open flame state or an intermittent operation state with a second preset power, the second preset power being lower than the first preset power.

4. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 3, characterized in that, The combustion monitoring device also includes an emergency purge valve, which is located on the central heating tube (3); The controller is interlocked with the feeding mechanism (2) and the emergency purge valve; When both the first flame detector and the second flame detector detect flameout, the controller executes an emergency shutdown procedure, including shutting down the feeding mechanism (2) and opening the emergency purge valve to inject purge medium into the central heating tube (3).

5. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 1, characterized in that, A water seal device (6) is provided on the section of the central heating pipe (3) located between the carbonization furnace (1) and the combustion chamber (5). The water seal device (6) is used to regulate the system pressure, provide a safety seal and prevent backfire. The water seal device (6) is equipped with a liquid level sensor and a regulating valve. The liquid level sensor is used to monitor the height of the liquid seal, and the regulating valve is connected to the liquid level sensor to maintain a constant height of the liquid seal. The carbonization furnace (1) is equipped with a pressure sensor to monitor the gas pressure inside the furnace; The carbonization furnace (1) is equipped with an exhaust fan in the gas emission path. The working power of the exhaust fan is adjusted according to the detection signal of the pressure sensor, which can control the negative pressure atmosphere inside the carbonization furnace (1).

6. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 1, characterized in that, The carbonization furnace (1) is a drum-type carbonization furnace. The carbonization furnace (1) is equipped with a rotary drive device (10). The rotary drive device (10) is used to drive the carbonization furnace (1) to rotate at a uniform speed and can adjust the rotation speed of the carbonization furnace (1) according to the raw material state or process stage. The central heating tube (3) is fixed and does not rotate with the carbonization furnace (1); The central axis of the central heating tube (3) coincides with the axis of the drum of the carbonization furnace (1). When the carbonization furnace (1) rotates, the material inside the furnace can fully contact the central heating tube (3).

7. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 6, characterized in that, The rotary drive device (10) includes at least two independent drive units to ensure torque balance through electrical synchronization control, thereby preventing the carbonization furnace (1) from torsional deformation; And / or, the carbonization furnace (1) is rotatably mounted on a base, the base including at least two pairs of rollers (11), the carbonization furnace (1) is provided with at least two sets of rolling rings (12), and the carbonization furnace (1) is rotatably supported on the rollers (11) by the rolling rings (12); And / or, the carbonization furnace (1) is rotatably mounted on a base, the base being provided with an adaptive self-aligning structure for compensating for the deformation of the carbonization furnace (1) caused by heating; And / or, the carbonization system further includes a speed monitoring sensor for triggering a safety interlock action when the speed is abnormal.

8. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 6, characterized in that, The inner wall of the carbonization furnace (1) is provided with a plurality of axially extending lifting plates, which are used to lift and scatter materials during the rotation of the carbonization furnace (1).

9. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 8, characterized in that, The installation direction of the lifting plate is set at an angle to the axis of the carbonization furnace (1), so that the material can be fed downstream while being thrown. And / or, the shape, density or installation angle of the scraper plate is set differently according to the temperature and functional zones inside the carbonization furnace (1).

10. The internal heating carbonization system based on countercurrent heat exchange with a central heating tube according to claim 1, characterized in that, The feed inlet and / or the carbon discharge outlet are provided with: A fixed cover (7) is provided, in which the end of the carbonization furnace (1) is rotatably disposed; A dynamic sealing mechanism is provided between the fixed cover (7) and the carbonization furnace (1), including a labyrinth seal and a flexible contact seal arranged sequentially along the gas leakage direction; The labyrinth sealing section includes: At least one set of labyrinth moving rings (21) are provided on the outer wall of the end of the carbonization furnace (1) and can rotate synchronously with the carbonization furnace (1); At least one set of labyrinth static rings (22) are provided on the inner wall of the fixed cover (7). The labyrinth static rings (22) and the labyrinth dynamic rings (21) are distributed alternately and at intervals along the axial direction, and together they form a tortuous flow channel. The flexible contact seal includes: A sealing ring (23) is fitted onto the end of the carbonization furnace (1) and is pressed between the carbonization furnace (1) and the fixed cover (7); A floating pressure cap (24) is provided on the side of the sealing ring (23) facing away from the labyrinth seal; The elastic force application unit (25) is pressed between the floating cover (24) and the fixed cover (7) to provide axial pressure to the floating cover (24) so ​​that the sealing ring (23) presses the carbonization furnace (1) and the fixed cover (7).

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