Wood fiber low-temperature drying device and method
By using a composite drying path and heat recovery system, the problems of fiber clumping, unevenness, and high energy consumption in low-temperature drying are solved, achieving efficient low-temperature uniform drying and energy utilization of wood fibers, protecting fiber quality and reducing energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-15
- Publication Date
- 2026-03-27
AI Technical Summary
While protecting the properties of wood fibers, low-temperature drying technology faces problems such as weakened moisture migration driving force, low drying rate, easy fiber clumping, uneven drying, and high energy consumption. Existing solutions deviate from the original intention of low temperature, making it difficult to balance quality and efficiency.
A composite drying path is adopted, consisting of a pulse dispersion component, a serpentine drying unit, an expansion buffer separation chamber, and a vortex drying tube. Combined with a heat recovery system, the fiber achieves uniform drying and energy utilization through inertial impact, airflow homogenization, swirling drying, and heat recovery.
The system achieves uniform drying of fibers under low-temperature conditions, avoiding keratinization, embrittlement, and yellowing, reducing energy consumption, improving drying rate and equipment stability, ensuring fiber quality, and recovering and utilizing waste gas heat energy.
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Figure CN121739725A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of wood fiber drying equipment, in particular to a wood fiber low-temperature drying device and method. BACKGROUND
[0002] Wood fiber is an important raw material in the fields of papermaking, wood-based panel and composite materials, etc. Its drying process is a key link in the production process, which directly affects the fiber quality and the performance of the final product. Traditional wood fiber drying usually adopts high-temperature airflow fast drying process, and the drying temperature is usually as high as 100℃ or above. Although the high-temperature drying efficiency is relatively high, high temperature (temperature higher than 90℃) can easily lead to the hornification, brittleness and even yellowing of wood fiber, which seriously damages the natural strength, length and color of the fiber, and reduces the product quality and added value.
[0003] In order to protect the characteristics of the fiber, low-temperature drying technology has gradually attracted attention. However, pure low-temperature drying (usually 50-70℃) faces new technical challenges: first, under low-temperature conditions, the driving force of water migration is weakened, and the drying rate is significantly reduced; second, wood fiber is fluffy and has a large specific surface area, which is easy to absorb moisture and form clumps in the early stage of drying, forming a hard core with internal wetness, leading to uneven drying, increased energy consumption, and even pipeline blockage, affecting continuous and stable production. In the prior art, in order to solve the problems of clumping and uniformity, it is often necessary to increase the airflow speed or temperature, which deviates from the original intention of low-temperature protection, and forms a contradiction between quality and efficiency.
[0004] In addition, the drying system has a huge energy consumption, and the exhaust gas discharged by the traditional device contains a large amount of low-grade waste heat and moisture. If it is directly discharged, not only the energy is wasted, but also the water vapor in the exhaust gas can increase the dew point temperature of the system environment, weaken the drying potential barrier, and affect the drying effect. SUMMARY
[0005] The technical solution of the present application provides a significantly different solution than the prior art to solve the technical problems in the prior art, mainly providing a wood fiber low-temperature drying device and method to solve the technical problems in the background art. The low-temperature drying is concerned for protecting the characteristics of the fiber, but the low temperature can weaken the driving force of water migration, and the drying rate is low; and the fiber is easy to absorb moisture and form clumps, which can cause uneven drying, pipeline blockage and other problems. The existing solution deviates from the original intention of low temperature, resulting in a contradiction between quality and efficiency. In addition, the drying system has a high energy consumption, and the direct discharge of waste heat and moisture in the exhaust gas not only wastes energy, but also weakens the drying effect.
[0006] The technical solution adopted by the present application to solve the above technical problems is: A wood fiber low-temperature drying device, comprising a heat source device and a drying device connected in sequence along the material flow direction. The heat source device comprises a heat source and a heat exchanger. Ventilation feeding pipe, connected to the air outlet end of the heat source device; Pulse dispersion assembly, connected to the outlet of the ventilation feeding pipe through an elbow, for inertial impact dispersion of the wet wood fiber mass, increasing the contact area between the fibers and the hot air; Expansion buffer separation chamber, for inertial classification and airflow homogenization of the dispersed fibers, separating and processing the heavy wet fibers; Vortex drying pipe, for uniform drying of the fibers in the rotational flow field, prolonging the material residence time; Drying fan, connected to the outlet of the vortex drying pipe; Cyclone separator, connected to the outlet of the drying fan; Dehumidification device, with its inlet connected to the exhaust port of the cyclone separator and its outlet connected to a three-way pipe; Heat recovery pipeline, connected between one of the air outlets of the three-way pipe and the air inlet of the heat source device, for recycling part of the dry waste air to the system inlet, realizing heat energy recycling; Heat supplement assembly, connected to the other air outlet of the three-way pipe and connected to multiple downward elbows through pipelines, for injecting hot air into the elbows where material is prone to accumulate, preventing fiber deposition and assisting drying.
[0007] Further preferably, the pulse dispersion assembly comprises multiple series-connected Venturi tube units; Each Venturi tube unit comprises an expansion section, a throat section, and a contraction section; The lower half of the expansion section of the Venturi tube unit is configured as an asymmetric structure that is steeper than the upper half.
[0008] Further preferably, the serpentine drying main body composed of at least one drying unit, each drying unit comprises an S-shaped structure formed by a downward elbow, a straight pipe, and an upward elbow connected in sequence; The downward elbow and the upward elbow are both 180° large-radius elbows.
[0009] Further preferably, the heat supplement assembly comprises a heat supplement fan, a heat supplement pipeline, a multi-way pipe, a connecting pipe, and a one-way valve; The air inlet of the heat supplement fan is connected to the three-way pipe, the air outlet is connected to the multi-way pipe through the heat supplement pipeline, and each air outlet of the multi-way pipe is connected to the corresponding downward elbow through the connecting pipe and the one-way valve; The heat supplement pipeline is internally provided with a heating module, and a temperature sensor is arranged near the multi-way pipe inside the heat supplement pipeline.
[0010] Further preferably, the vortex drying pipe is a straight pipe, and a plurality of helical guide vanes are fixed to the inner wall of the pipe; The included angle between the helical guide vane and the pipeline axis is 15 to 45 degrees, and the height of the helical guide vane is 0.2 to 0.4 times the radius of the pipeline.
[0011] Further preferably, the expansion buffer separation chamber is connected to the lower elbow outlet, which is a vertical cavity with a diameter larger than its connecting pipeline, and both its inlet and outlet are trumpet-shaped gradually expanding tubes or gradually tapered tubes.
[0012] Further preferably, the air inlet of the heat source device is provided with an air inlet fan, and the air outlet is provided with a temperature sensor. The air inlet end of the air inlet fan is provided with an air inlet guide cover, and the center point of the air inlet fan and the center point of the air outlet of the heat recovery pipeline are on the same horizontal line.
[0013] Further preferably, the outer wall of the ventilation feeding pipe is provided with a feeding port, and the feeding port is provided with a first air locking feeder, and the feeding port of the first air locking feeder is provided with a feeding hopper. The discharge port of the cyclone separator is provided with a second air locking feeder. The two air outlet ends of the three-way pipe are provided with valves.
[0014] A low-temperature drying method of wood fibers, comprising the following steps: Step one, start the air inlet fan and electric heating / gas heating module of the heat source device, and at the same time start the drying fan; The temperature of the hot air outlet of the heat source device is monitored by the temperature sensor, and the temperature is adjusted to the target range of 50-70℃; The hot air is circulated in the system composed of ventilation feeding pipe, pulse dispersion assembly, serpentine drying unit, expansion buffer separation chamber, vortex drying pipe and connected pipeline.
[0015] Step two, add wet wood fibers to the feeding hopper, and if necessary, start the vibrator or knocking device on it to prevent material sticking; The wet fibers pass through the rotating partition plate of the first air locking feeder to realize continuous, uniform and sealed feeding, and enter the ventilation feeding pipe to mix with hot air; The fiber and air flow mixture enters the pulse dispersion assembly through the ninety-degree elbow pipe, and successively flows through a plurality of series connected Venturi tube units, and at the throat part of the Venturi tube, shear force is generated due to air flow acceleration, and under the action of the steeper asymmetric structure of the lower half of the expansion section, impact dispersion of the fiber group is realized.
[0016] Step three, the preliminarily dispersed mixture successively flows through the serpentine drying unit composed of the upper elbow, straight pipe and the lower elbow; When flowing through the expansion buffer separation chamber, the diameter of the cavity is increased, the air flow velocity is reduced, and the separation and homogenization of heavy wet fibers and light dry fibers are realized by using inertial force; Subsequently, the mixture enters the vortex drying tube, and under the action of the helical guide vanes fixed to the inner wall of the vortex drying tube, the mixture is subjected to rotational movement, the residence time is prolonged, and uniform and thorough drying is achieved.
[0017] Step four, the dried fibers and the gas mixture are transported by the drying fan to the cyclone separator. In the cyclone separator, gas-solid separation is completed, and the dried wood fibers are continuously and sealingly discharged from the system through the rotating partition plate of the second air-locking feeder.
[0018] Step five, the separated exhaust gas enters the dehumidifying device for deep dehumidification. The dry air after dehumidification is distributed through the three-way pipe: a part of the dry air is returned to the air inlet of the heat source device through the regenerative pipeline, mixes with the fresh air introduced by the air inlet guide cover, and then enters the system circulation to realize heat recovery. Another part enters the heat supplement assembly, is heated by the heating module, is transported by the heat supplement fan, is tangentially injected into a plurality of corresponding elbow pipes through the connecting pipe and the one-way valve, and is used as a cleaning gas flow to prevent fiber deposition.
[0019] Further preferably, in step five, the opening degree of the valve on the three-way pipe is automatically adjusted by detecting the humidity parameter of the exhaust gas to control the proportion of the internal circulation exhaust gas. The power of the heating module is adjusted by the temperature sensor in the heat supplement pipeline.
[0020] Compared with the prior art, the present application has the following advantages: 1. The drying device uses a composite and multi-stage drying path composed of a pulse dispersion assembly, a serpentine drying unit, an expansion buffer separation chamber, and a vortex drying tube. First, the wet fibers that are prone to clumping are dispersed by the inertial difference and turbulent force generated by the Venturi effect and the asymmetric structure. Then, the residence time is prolonged in the serpentine pipe, and preliminary classification is performed by the centrifugal force of the elbow. Then, the heavy wet fibers are separated by the sudden speed drop in the expansion buffer chamber. Finally, the fibers are uniformly scattered and three-dimensionally contacted by the spiral motion in the vortex pipe. Therefore, under the condition of low temperature of 50-70 DEG C, the fibers can still be uniformly and thoroughly dried from the surface to the inside, thereby avoiding the problems of external dryness and internal wetness, fiber clumping, uneven drying, and traditional high-temperature drying, which can cause hornification, brittleness, and yellowing of wood fibers due to overheating. The fiber quality can be protected.
[0021] 2、The drying device, through the waste gas energy grading recovery system of the rotary dehumidifier, three-way pipe and heat supplement assembly, first utilizes the rotary dehumidifier to deeply dehumidify the waste gas at the end of the system, obtains low dew point air, and then adjusts the valve of the three-way pipe, and the part of the dehumidified waste gas is heated through the heating module of the heat supplement assembly, and is tangentially injected into the lower elbow area of the material prone to accumulation through the connecting pipe and the one-way valve. This has the following effects. On the one hand, the tangential entering airflow forms a rotating sweep in the elbow, preventing the deposition and blockage of fibers on the bottom of the pipeline due to gravity and centrifugal force, ensuring the smoothness of the flow path. On the other hand, the injected heated dry gas serves as an auxiliary heat source to locally supplement the heating of the fibers that may not have been completely dried, enhancing the drying effect, thereby achieving the dual purposes of preventing blockage and auxiliary drying, and improving the stability of the device operation.
[0022] 3、The drying device, by arranging the outlet of the heat recovery pipeline near the air inlet guide cover of the air inlet fan of the heat source device, and ensuring that the center is coaxial with the center of the fan and is in close proximity, the other part of the low-temperature and low-humidity waste gas treated by the dehumidifying device can be introduced back to the system inlet, thereby reducing the dependence on the new air of the environment, and the initial absolute moisture content of the air supplemented into the system is reduced, creating a low-humidity driving environment for the entire drying process from the source, strengthening the mass transfer driving force of water migration from the inside of the fiber to the dry air under low-temperature conditions, thereby improving the drying rate and the final effect.
[0023] The application will be explained in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 is a schematic diagram of the three-dimensional structure of the application; Figure 2 is a schematic diagram of the top view structure of the application; Figure 3 is a schematic diagram of the side view structure of the application; Figure 4 is a schematic diagram of the rear view structure of the application; Figure 5 is a schematic diagram of the air lock feeder structure of the application; Figure 6 is a schematic diagram of the Venturi tube unit structure of the application.
[0025] Markings in the figure: 1, heat source device; 2, ventilation feeding pipe; 3, first air lock feeder; 4, feeding hopper; 5, pulse dispersion assembly; 6, upper elbow; 7, straight pipe; 8, lower elbow; 9, expansion buffer separation chamber; 10, vortex drying pipe; 11, drying fan; 12, cyclone separator; 13, second air lock feeder; 14, dehumidifying device; 15, three-way pipe; 16, heat supplement assembly; 17, heat recovery pipeline. DETAILED DESCRIPTION
[0026] In order to facilitate the understanding of the present application, a more comprehensive description will be made below with reference to the relevant drawings, which show several embodiments of the present application. However, the present application can be realized in different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.
[0027] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can be a middle element, and when an element is referred to as being "connected to" another element, it can be directly connected to the other element or there can be a middle element. The terms "vertical", "horizontal", "left", "right" and the like used herein are for illustrative purposes only.
[0028] Please refer to the drawings Figures 1-6 , a wood fiber low-temperature drying device,
[0029] Embodiment 1: including heat source device 1, ventilation feeding pipe 2, first air-lock feeder 3, feeding hopper 4, pulse dispersion assembly 5, at least one drying unit formed by upper elbow 6, straight pipe 7 and lower elbow 8 in series, expansion buffer separation chamber 9, vortex drying pipe 10, drying fan 11, cyclone separator 12, second air-lock feeder 13, dehumidification device 14, three-way pipe 15, heat supplement assembly 16 and regenerative pipeline 17.
[0030] It also includes a control system for adjusting the rotational speed of the air inlet fan, drying fan 11 and heat supplement fan based on the pipeline pressure signal to maintain system pressure balance.
[0031] In this embodiment, as shown in Figure 1 , Figure 2 , Figure 3 and Figure 4 , the air inlet of heat source device 1 is provided with an air inlet fan, and the air volume ratio of drying fan 11 to air inlet fan is 1:1.2-1.5, and the air outlet of heat source device 1 is provided with a temperature sensor. The air inlet end of the air inlet fan is provided with an air inlet guide cover, and the center point thereof is located on the same horizontal line as the center point of the air outlet of regenerative pipeline 17, and the distance therebetween is close, so as to ensure that the return air can be smoothly sucked in and uniformly mixed. The air outlet end of heat source device 1 is connected with ventilation feeding pipe 2. The air outlet end of heat source device 1 is connected with the flange of ventilation feeding pipe 2.
[0032] The heat source device 1 can be provided with a heating element such as a gas pipeline or an electric heating tube. The heat source device 1 integrates an automatic control system with a PID control algorithm as the core. The system constitutes a closed-loop feedback circuit: a temperature sensor detects the air temperature in real time and feeds back to a programmable logic controller; the PLC compares the detection value with a preset target temperature value (such as 60°C), calculates the control signal through the PID algorithm, and then drives the actuator. If it is an electric heating tube, the output power of the solid-state relay (SSR) or thyristor is adjusted; if it is a gas heating, the opening of the gas electric regulating valve is adjusted, so that the heating power is steplessly adjusted, and the hot air temperature is stabilized in the set range of 50-70°C.
[0033] In this embodiment, as shown in Figure 1 、 Figure 2 and Figure 3 , the outer wall of the ventilation feeding pipe 2 is provided with a feeding port, and the feeding port is provided with a first wind-locking feeder 3. The feeding port of the first wind-locking feeder 3 is provided with a feeding hopper 4, and a vibrator or a knocking device can be arranged on the feeding hopper 4 to prevent the material from sticking. A support is arranged at the lower part of the ventilation feeding pipe 2.
[0034] In this embodiment, as shown in Figure 1 、 Figure 2 、 Figure 3 and Figure 6 , the pulse dispersion assembly 5 is connected to the outlet of the ventilation feeding pipe 2 through a ninety-degree elbow. The pulse dispersion assembly 5 includes a plurality of series-connected Venturi tube units, each of which includes an expansion section, a throat section, and a contraction section, and the lower half of the expansion section is designed to be more asymmetric than the upper half, the inclination angle ratio of the lower half to the upper half of the expansion section of each Venturi tube unit is 1.5:1 to 3:1, and a wear-resistant ceramic lining is arranged in the Venturi tube unit to enhance the bottom airflow speed, prevent fiber deposition, and enhance the fiber cluster breaking effect by using inertia.
[0035] In this embodiment, as shown in Figure 1 、 Figure 2 and Figure 4 , the outlet of the pulse dispersion assembly 5 is connected to a straight pipe 7 through an upper elbow 6, and the outlet of the straight pipe 7 is connected to an expansion buffer separation chamber 9 through a lower elbow 8. The upper elbow 6 and the lower elbow 8 are both 180° large-radius elbows. The expansion buffer separation chamber 9 is a vertical cavity with a diameter larger than that of the connecting pipeline, the cavity diameter is 2-3 times that of the connecting pipeline, the inlet and outlet of the cavity are both trumpet-shaped gradually expanding pipes or gradually tapering pipes, which are used to slow down the airflow and separate and homogenize the heavy wet fibers and the light dry fibers by using the inertial force. A support is arranged at the lower part of the lower elbow 8.
[0036] In this embodiment, as shown in Figure 1 、 Figure 3 and Figure 4As shown, the outlet of the expansion buffer separation chamber 9 is connected to the vortex drying tube 10 sequentially via an upper elbow 6, a straight pipe 7, and a lower elbow 8. The vortex drying tube 10 is a straight tube with several spiral guide vanes fixed to its inner wall. The angle between the spiral guide vanes and the pipe axis is 15 to 45 degrees, and their height is 0.2 to 0.4 times the pipe radius. These vanes are used to guide the fibers to generate spiral motion, prolong the residence time, and achieve uniform and deep drying.
[0037] The expansion buffer separation chamber 9 is also equipped with a dehumidification port and a discharge pipe, and a corresponding pneumatic dehumidification valve is installed. When the internal humidity sensor detects that the humidity in the settling area is >40%, it will automatically open to discharge the settled heavy wet fibers in time, thereby ensuring the drying uniformity of the mainstream fibers and preventing blockage at the bottom of the separation chamber.
[0038] In this embodiment, as Figure 1 , Figure 3 and Figure 5 As shown, the outlet of the vortex drying tube 10 is connected to the inlet of the cyclone separator 12 via the drying fan 11. A second airlock feeder 13 is installed at the outlet of the cyclone separator 12. Both the first airlock feeder 3 and the second airlock feeder 13 include a housing, a motor, a shaft, and multiple partition plates arranged in a ring around the shaft's centerline, used to achieve continuous, sealed material conveying and prevent gas leakage between the inside and outside of the system.
[0039] In this embodiment, as Figure 1 and Figure 2 As shown, the exhaust port of the cyclone separator 12 is connected to the inlet of the dehumidifier 14 via a pipe. The dehumidifier 14 can be a rotary dehumidifier. The outlet of the dehumidifier 14 is connected to a three-way pipe 15, and both outlet ends of the three-way pipe 15 are equipped with electric or pneumatic regulating valves.
[0040] One outlet of the three-way pipe 15 is connected to the air inlet of the heat source device 1 via the regenerating pipe 17, which is used to return part of the dried exhaust gas to the system inlet to realize heat energy recovery and utilization. A support is provided at the bottom of the regenerating pipe 17. The other outlet of the three-way pipe 15 is connected to the supplementary heating component 16.
[0041] In this embodiment, as Figure 1 and Figure 2 As shown, the heating assembly 16 includes a heating fan, a heating pipe, a multi-way pipe, a connecting pipe, and a one-way valve. The heating fan is connected to the valve of the three-way pipe 15, and its outlet is connected to the multi-way pipe through the heating pipe. Each outlet of the multi-way pipe is tangentially connected to the corresponding lower elbow 8 through the connecting pipe and the one-way valve. A heating module is installed inside the heating pipe, and a temperature sensor is installed inside the pipe near the multi-way pipe to provide controllable auxiliary hot air to areas prone to material accumulation, preventing blockage and enhancing local drying. The heating module is an electric heating wire or a hot water coil, and the outlet temperature can be controlled between 50-70℃.
[0042] A method for low-temperature drying of wood fibers, comprising the following steps: Step one, start the air inlet fan and the electric / gas heating module of the heat source device 1, and simultaneously start the drying fan 11; The temperature of the hot air outlet of the heat source device 1 is monitored by a temperature sensor, and the temperature is adjusted to a target range of 50-70℃; The hot air is circulated in the system composed of the ventilation feed pipe 2, the pulse dispersion assembly 5, the serpentine drying unit, the expansion buffer separation chamber 9, the vortex drying pipe 10, and the connected pipelines.
[0043] Step two, wet wood fibers are added to the feed hopper 4, and the vibrator or knocking device on it is started if necessary to prevent material adhesion; The wet fibers are continuously, uniformly, and sealingly fed through the rotating partition plate of the first air-lock feeder 3, and enter the ventilation feed pipe 2 to mix with hot air; The fiber-air flow mixture enters the pulse dispersion assembly 5 through a ninety-degree elbow, and sequentially flows through multiple series-connected Venturi tube units. At the throat of the Venturi tube, shear force is generated due to airflow acceleration, and the impact dispersion of fiber clusters is realized under the action of the more steep asymmetric structure in the lower half of the expansion section.
[0044] Step three, the preliminarily dispersed mixture sequentially flows through the serpentine drying unit composed of the upper elbow 6, the straight pipe 7, and the lower elbow 8; When flowing through the expansion buffer separation chamber 9, the airflow velocity decreases due to the increase in the diameter of the chamber, and the separation and homogenization of heavy wet fibers and light dry fibers are realized by using inertial force; Subsequently, the mixture enters the vortex drying pipe 10, and under the action of the fixed helical guide vanes on the inner wall, it produces rotational motion, prolongs the residence time, and realizes uniform and deep drying.
[0045] Step four, the dried fiber-air flow mixture is transported by the drying fan 11 to the cyclone separator 12; In the cyclone separator 12, gas-solid separation is completed, and the dried wood fibers are continuously and sealingly discharged from the system through the rotating partition plate of the second air-lock feeder 13.
[0046] Step five, the separated exhaust gas enters the dehumidification device 14 for deep dehumidification; The dry air after dehumidification is distributed through the three-way pipe 15: part of it is returned to the air inlet of the heat source device 1 through the regenerative pipeline 17, mixes with the fresh air introduced by the air inlet guide cover, and then enters the system circulation to realize heat recovery; Another part enters the heat supplement assembly 16, is heated by the heating module, is transported by the heat supplement fan, is injected into a plurality of corresponding lower elbows 8 through the connecting pipe and the one-way valve as a cleaning airflow to prevent fiber deposition.
[0047] In this embodiment, as shown in Figure 1 and Figure 2 In step S5, the humidity parameter of the exhaust gas at the outlet of the dehumidification device 14 is detected in real time by the humidity sensor at the outlet of the dehumidification device 14, and the opening of the two valves on the three-way pipe 15 is automatically adjusted, so as to control the proportion of the internal circulating exhaust gas entering the regenerative pipeline 17 and the proportion of the exhaust gas entering the heat supplement assembly 16, and to realize self-adaptive optimization of energy utilization according to the drying stage, such as high humidity in the early stage or low humidity in the later stage. At the same time, the temperature of the cleaning airflow about to be injected into the lower elbow 8 is monitored in real time by the temperature sensor arranged near the multi-way pipe in the heat supplement pipeline, and the power of the heating module inside the heat supplement pipeline is dynamically adjusted according to the feedback signal, so as to ensure that the temperature of the cleaning airflow is stable within a preset range, which can prevent fiber deposition at the elbow and avoid local overheating damage to the fiber.
[0048] In example 2, the layout of the drying unit is further optimized based on example 1. According to the actual site and production capacity demand, the drying unit composed of the upper elbow 6, the straight pipe 7 and the lower elbow 8 can be connected in multiple stages to form a longer serpentine drying path, so as to further prolong the drying time and improve the drying uniformity. The connection mode between the drying units at different stages is the same as that in example 1.
[0049] In example 3, the heat supplement assembly 16 is refined based on example 1. The heat supplement fan of the heat supplement assembly 16 can be a variable frequency fan, which can automatically adjust the air speed according to the pressure difference sensor signal at the lower elbow 8 to realize on-demand cleaning. The heating module can adopt a PID temperature control system to form a closed loop control with the temperature sensor in the pipeline, so as to more accurately control the temperature of the cleaning airflow injected into the lower elbow 8 and stabilize it within an optimal range, which can prevent material accumulation, avoid energy waste and prevent fiber heat damage.
[0050] The above description of the application is exemplary in combination with the drawings, and it is obvious that the specific implementation of the application is not limited by the above method. Any non-essential improvement or direct application of the concept and technical solution of the application to other occasions is within the protection scope of the application.
Claims
1. A wood fiber low-temperature drying apparatus, characterized by, The device comprises, in sequence along the material flow direction: a heat source device (1); a ventilation feeding pipe (2) connected to the air outlet end of the heat source device (1); a pulse dispersion assembly (5) connected to the outlet of the ventilation feeding pipe (2) through an elbow pipe, for performing inertial impact dispersion on the wet wood fiber mass, increasing the contact area of the fibers and hot air; an expansion buffer separation chamber (9) for performing inertial classification and airflow homogenization on the dispersed fibers, separating and processing the heavy wet fibers; a vortex drying pipe (10) for uniformly drying the fibers in a vortex field, prolonging the material residence time; a drying fan (11) connected to the outlet of the vortex drying pipe (10); a cyclone separator (12) connected to the outlet of the drying fan (11); a dehumidification device (14) with its inlet connected to the exhaust port of the cyclone separator (12) and its outlet connected to a three-way pipe (15); a heat recovery pipeline (17) connected between one air outlet end of the three-way pipe (15) and the air inlet of the heat source device (1), for returning part of the dry waste air to the system inlet, realizing heat energy recycling; a heat supplement assembly (16) connected to the other air outlet end of the three-way pipe (15) and tangentially connected to multiple lower elbows (8) through pipes, for injecting hot air into the elbows prone to material accumulation, preventing fiber deposition and assisting drying.
2. A wood fiber low temperature drying apparatus according to claim 1, characterized in that: The pulse dispersion assembly (5) comprises multiple series-connected Venturi tube units. Each Venturi tube unit comprises an expansion section, a throat section and a contraction section. The lower half of the expansion section of the Venturi tube unit is configured as an asymmetric structure that is steeper than the upper half.
3. A wood fiber low temperature drying apparatus according to claim 1, characterized in that: A serpentine drying main body composed of at least one drying unit, each drying unit comprising an S-shaped structure formed by a upper elbow (6), a straight pipe (7) and a lower elbow (8) connected in sequence; The lower elbow (8) and the upper elbow (6) are both 180° large-radius elbows.
4. A wood fiber low temperature drying apparatus according to claim 1, characterized in that: The heat supplement assembly (16) comprises a heat supplement fan, a heat supplement pipe, a multi-way pipe, a connecting pipe and a one-way valve; The air inlet of the heat supplement fan is connected to the three-way pipe (15), the air outlet of the heat supplement fan is connected to the multi-way pipe through the heat supplement pipe, and each air outlet of the multi-way pipe is tangentially connected to a corresponding lower elbow (8) through the connecting pipe and the one-way valve; The heat supplement pipe is internally provided with a heating module, and a temperature sensor is arranged near the multi-way pipe inside the heat supplement pipe.
5. A wood fiber low temperature drying apparatus according to claim 1, characterized in that: The vortex drying pipe (10) is a straight pipe, and a plurality of helical guide vanes are fixed to the inner wall of the pipe; The included angle between the helical guide vane and the pipe axis is 15 to 45 degrees, and the height of the helical guide vane is 0.2 to 0.4 times the radius of the pipe.
6. A wood fiber low temperature drying apparatus according to claim 3, characterized in that: The expansion buffer separation chamber (9) is connected to the outlet of the lower elbow (8), and is a vertical cavity with a larger diameter than the connecting pipe, and the inlet and outlet of the expansion buffer separation chamber (9) are both trumpet-shaped gradually expanding pipes or gradually tapered pipes.
7. A wood fiber low temperature drying apparatus according to claim 1, characterized in that: The air inlet of the heat source device (1) is provided with an air inlet fan, and the air outlet is provided with a temperature sensor; The air inlet end of the air inlet fan is provided with an air inlet flow guide cover, and the center point of the air inlet fan and the center point of the air outlet of the heat recovery pipeline (17) are on the same horizontal line.
8. A wood fiber low temperature drying apparatus according to claim 1, characterized in that: The outer wall of the ventilation feeding pipe (2) is provided with a feeding port, and a first air locking feeder (3) is mounted on the feeding port, and a feeding hopper (4) is mounted on the feeding port of the first air locking feeder (3); The discharge port of the cyclone separator (12) is provided with a second air-locking feeder (13); Both of the two gas outlets of the tee pipe (15) are provided with valves.
9. A method for low-temperature drying of wood fibers using a low-temperature drying device for wood fibers according to any one of claims 1 to 8, characterized in that The method comprises the following steps: Step one, start the air inlet fan and heating module of the heat source device (1), and simultaneously start the drying fan (11); The temperature of the hot air is monitored by the temperature sensor at the air outlet of the heat source device (1), and is adjusted to the target range of 50-70℃; The hot air is circulated in the system composed of the ventilation feeding pipe (2), the pulse dispersion assembly (5), the serpentine drying unit, the expansion buffer separation chamber (9), the vortex drying pipe (10) and the connecting pipes to form a circulating air flow; Step two, wet wood fibers are added into the feeding hopper (4), and the wet fibers are continuously, uniformly and sealingly fed into the ventilation feeding pipe (2) through the rotating partition plate of the first air-locking feeder (3) and mixed with the hot air; The fiber-air flow mixture enters the pulse dispersion assembly (5) through the elbow pipe, and sequentially flows through multiple series-connected Venturi pipe units, so that the shear force is generated at the throat of the Venturi pipe due to the air flow acceleration, and the impact dispersion of the fiber group is realized under the action of the more steep asymmetric structure in the lower half of the expansion section of the Venturi pipe; Step three, the preliminarily dispersed mixture sequentially flows through the serpentine drying unit composed of the upper elbow (6), the straight pipe (7) and the lower elbow (8); When flowing through the expansion buffer separation chamber (9), the air flow speed is reduced due to the increase of the cavity diameter, and the separation and homogenization of the heavy wet fibers and the light dry fibers are realized by using the inertial force; Subsequently, the mixture enters the vortex drying pipe (10), and rotates under the action of the fixed helical guide vane on the inner wall of the vortex drying pipe, so that the residence time is prolonged, and uniform and deep drying is realized; Step four, the dried fiber-air flow mixture is transported to the cyclone separator (12) by the drying fan (11); The gas-solid separation is completed in the cyclone separator (12), and the dried wood fibers are continuously and sealingly discharged from the system through the rotating partition plate of the second air-locking feeder (13); Step five, the separated waste gas enters the dehumidification device (14) for deep dehumidification; The dry air after dehumidification is distributed through the tee pipe (15): part of the dry air is returned to the air inlet of the heat source device (1) through the heat recovery pipe (17), mixed with the fresh air introduced by the air inlet guide cover, and then enters the system circulation to realize heat recovery; The other part enters the heat supplement assembly (16), is heated by the heating module of the heat supplement assembly (16), is transported by the heat supplement fan, is tangentially injected into multiple corresponding lower elbows (8) through the connecting pipe and the one-way valve, and is used as the cleaning air flow to prevent fiber deposition.
10. A method of drying wood fibres at low temperature according to claim 9, characterized in that: In step five, the opening degree of the valve on the tee pipe (15) is automatically adjusted according to the humidity parameter of the waste gas to control the proportion of the internal circulating waste gas; The power of the heating module is adjusted according to the feedback of the temperature sensor in the heat supplement pipe.