A dryer

Abstract

The utility model discloses a dryer, including steam generator, steam delivery pipe, frame, first cover, second cover, exhaust fan, power device, mesh belt conveying unit, steam heating pipe and water vapor return pipe, the upper portion of frame is equipped with the first cover all around, and the lower part of frame is left with the air inlet, and the top of frame is equipped with second cover and exhaust fan, and the exhaust fan is the exhaust fan of continuous speed regulation, and the mesh belt conveying unit and steam heating pipe of more than three layers are installed in the vertical direction in the frame, and the steam heating pipe of the even arrangement of a layer of corresponding each layer mesh belt conveying unit below is whole and is rectangular, and the running direction of the mesh belt of adjacent two layers mesh belt conveying units is opposite, and the material of the discharge end of last layer mesh belt conveying unit falls and can fall on the mesh belt of the feeding end of next layer mesh belt conveying unit. The utility model has solved the problem of uneven drying, high heat energy loss, local heat accumulation and even causing the spontaneous combustion of traditional chinese medicinal materials when the existing dryer is used for drying traditional chinese medicinal materials.

Description

Technical Field

[0001] This utility model relates to the field of dryer technology. Background Technology

[0002] Chinese medicinal materials are mainly divided into three categories: plant-based medicines (such as ginseng and astragalus), animal-based medicines (such as deer antler and centipede), and mineral-based medicines (such as cinnabar and gypsum).

[0003] Drying Chinese medicinal herbs is a crucial step in their processing, directly impacting their quality, preservation, the stability of their medicinal components, and their market value. Traditional methods for drying Chinese medicinal herbs often involve natural air drying or simple drying rooms. These methods are not only inefficient and space-consuming but also heavily reliant on weather conditions, making it difficult to guarantee the stability and consistency of the herbs' quality. With the increasing market demand and higher quality requirements for Chinese medicinal herbs, efficient, energy-saving, and controllable mechanized drying equipment is gradually becoming the inevitable choice for the industry's development.

[0004] Chinese medicinal herbs are diverse in type and characteristics. Some contain volatile components, some have high sugar content, and some are fragile, which places higher demands on drying equipment. Ideal drying equipment should be able to precisely control the drying temperature, air velocity, and humidity according to the characteristics of Chinese medicinal herbs, achieving uniform drying as needed, while ensuring energy efficiency and production safety.

[0005] However, existing dryers still have many problems when used to dry Chinese medicinal materials: uneven drying; excessive heat loss, leading to a significant increase in production costs; local heat accumulation, which may even cause spontaneous combustion of Chinese medicinal materials, seriously threatening production safety. Utility Model Content

[0006] To address the problems of uneven drying, high heat loss, localized heat accumulation, and even spontaneous combustion of Chinese medicinal herbs when using existing dryers, this utility model provides a dryer.

[0007] The technical solution adopted in this utility model is as follows:

[0008] A dryer includes a steam generator, a steam conveying pipe, a frame, a first cover plate, a second cover plate, an exhaust fan, a power unit, a mesh belt conveyor unit, a steam heating pipe, and a water vapor return pipe. One end of the steam conveying pipe has a steam inlet connected to the steam outlet of the steam generator. The frame is a multi-layered rectangular frame structure. The upper part of the frame has a first cover plate installed around its perimeter. The lower part of the frame has an air inlet, and the top of the frame has a second cover plate with several air outlets. Each air outlet is equipped with an exhaust fan, which is continuously adjustable in speed. The frame contains three or more layers of mesh belt conveyor units and steam heating pipes installed vertically. Below each layer of mesh belt conveyor units is a uniformly arranged, rectangular steam heating pipe. The steam heating pipe has two adjacent mesh belt conveyor units with opposite running directions, and the two ends of the mesh belt conveyor units are staggered at the ends in the running direction. The material falling from the unloading end of the upper mesh belt conveyor unit can fall onto the feeding end of the lower mesh belt conveyor unit. The power device is an electric motor or an electric motor with a reducer. The power device is installed on the frame, the first cover plate, the second cover plate, or the working area of ​​the dryer. The power device is connected to the mesh belt conveyor unit through a transmission component. The steam inlet of each layer of steam heating pipe is connected to the steam outlet of the steam conveying pipe. The water vapor outlet of each layer of steam heating pipe is connected to the water vapor inlet of the water vapor return pipe. The water vapor outlet of the water vapor return pipe is connected to the return water port of the steam generator.

[0009] Preferably, it also includes a steam filter, which is installed on the steam delivery pipe.

[0010] Preferably, the power unit consists of two electric motors or two electric motors with reducers. Each of the two electric motors or reducers is connected to one of the two mesh belt conveyor units with opposite mesh belt running directions, and the mesh belt conveyor units with the same mesh belt running direction are connected to each other.

[0011] Preferably, the power unit is two electric motors or two electric motors with reducers. The transmission assembly includes a drive sprocket, a first-stage chain, a first-stage driven sprocket, and a second-stage chain. The first-stage driven sprocket is a double sprocket. Each electric motor or reducer has a drive sprocket mounted on its power output shaft. Each mesh belt conveyor unit has a first-stage driven sprocket mounted at one end of its power input shaft. The two drive sprockets are each connected to the first-stage driven sprocket of one of the two mesh belt conveyor units with opposite mesh belt running directions via a first-stage chain drive. The first-stage driven sprockets of mesh belt conveyor units with the same mesh belt running direction are connected via a second-stage chain drive.

[0012] Preferably, the mesh belt conveyor unit includes bearings, a power input shaft, a driven shaft, a first sprocket, a second sprocket, a first chain, and a mesh belt. The power input shaft is horizontally mounted at one end of the frame along its length via bearings, and the driven shaft is horizontally mounted at the other end of the frame along its length via bearings. The power input shaft and the driven shaft are parallel. A pair of first sprockets are mounted on the power input shaft, and a pair of second sprockets are mounted on the driven shaft. A first chain is mounted at each end of the mesh belt parallel to its running direction. The first chain meshes with the first and second sprockets and is tensioned.

[0013] Preferably, the steam heating pipe is a multi-turn right-angle rotary coil or a rectangular wave tube.

[0014] Preferably, both the steam delivery pipe and the water vapor return pipe include at least a vertical pipe. The vertical pipe of the steam delivery pipe has three or more steam outlets at different heights, and the vertical pipe of the water vapor return pipe has three or more water vapor inlets at different heights. The steam inlet of each layer of steam heating pipe is connected to the steam outlet at the corresponding height on the vertical pipe of the steam delivery pipe, and the water vapor outlet of each layer of steam heating pipe is connected to the water vapor inlet at the corresponding height on the vertical pipe of the water vapor return pipe.

[0015] Preferably, the exhaust fan is a continuously variable speed exhaust fan or an exhaust fan with a thyristor speed control.

[0016] Preferably, it also includes a feeding device for moving the material to be dried onto the feeding end of the uppermost mesh belt conveyor unit.

[0017] Preferably, the feeding device is a conveyor or a feeding hopper.

[0018] Preferably, a material discharge device is provided below the discharge end of the lowest mesh belt conveyor unit to discharge the falling material from the frame.

[0019] Preferably, the material discharge device is a conveyor or an inclined guide trough.

[0020] This invention allows the Chinese medicinal herbs to be dried to pass through three layers of mesh belts. During each layer, an exhaust fan mounted on the second cover plate at the top of the frame draws air in from the air inlet at the bottom of the frame and directs it upwards. As the air flows upwards through the steam heating pipes, it is heated, and this heating occurs once per layer of steam heating pipes. Simultaneously, the steam within the pipes is cooled into water vapor. As the hot air continues to flow upwards through the mesh openings of each layer of mesh belts, it heats the Chinese medicinal herbs on that layer and carries away the evaporated water vapor. Finally, the air and water vapor flowing through the mesh openings of the top layer of mesh belts are drawn away and discharged by the exhaust fan. The process of drying the Chinese medicinal herbs from top to bottom is achieved by... Each time the medicinal herbs pass through a mesh belt conveyor unit, they are dried once, with their moisture content decreasing sequentially. The herbs that finally fall from the bottommost mesh belt conveyor unit's discharge end are those that have met the drying requirements or have reached a certain degree of dryness. Herbs that have not yet met the drying requirements can be dried again using the same process until they do. As the herbs move along the mesh belt, the side facing the mesh belt is in direct contact with the upward-flowing hot air, resulting in faster moisture evaporation on that side. During the process of the herbs falling from the discharge end of one mesh belt conveyor unit to the loading end of the next, the side with higher moisture content is dried more quickly than the other side. One side is heavier, so during the descent, the medicinal herbs flip over, with the side with higher moisture content facing down. Finally, the herbs land on the feed end of the next conveyor belt and come to a stop, with the side with higher moisture content facing down (in this state, the center of gravity is lower and the stability is better). In this way, each time the herbs fall from the feed end of the upper conveyor belt to the feed end of the lower conveyor belt, the side with higher moisture content always faces the feed end of the lower conveyor belt, achieving rapid and uniform drying. The air and water vapor flowing past the lower conveyor belt with lower moisture content can release residual heat as the airflow continues upwards across the upper conveyor belt. This invention fully utilizes the high moisture content of traditional Chinese medicinal materials. Therefore, the dryer of this invention has the advantages of low heat loss, high energy utilization efficiency, and energy saving. Compared with drying methods that use electric heating, the dryer uses hot air flowing through uniformly arranged rectangular steam heating pipes to dry the traditional Chinese medicinal materials moving with the conveyor belt. The materials are heated more evenly, without local heat accumulation or spontaneous combustion. By adjusting the speed of the exhaust fan, and if necessary, by adjusting the heating power of the steam generator to adjust the speed or temperature of the steam generated, the speed of the airflow flowing through the steam heating pipes, the speed and temperature of the airflow flowing through the traditional Chinese medicinal materials to be dried, and the rate of moisture evaporation of the materials can be easily adjusted, thereby meeting the different drying needs of various traditional Chinese medicinal materials. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of a portion of the dryer according to an embodiment of the present utility model;

[0022] Figure 2 for Figure 1 The diagram shows a front view of part of the dryer's structure.

[0023] Figure 3 for Figure 2 The diagram shows an enlarged view of part of the dryer's structure at point A.

[0024] Figure 4 for Figure 2 The diagram shows an enlarged view of part of the dryer's structure at point B.

[0025] Figure 5 for Figure 2 A front view schematic diagram of the steam heating pipe in a portion of the dryer's structure;

[0026] Figure 6 This is a front view schematic diagram of another steam heating pipe that can be used in the dryer of this utility model;

[0027] In the diagram: 1. Steam conveying pipe; 2. Frame; 3. First cover plate; 4. Mesh belt; 5. Chain 1; 6. Sprocket 1; 7. Sprocket 2; 8. First stage driven sprocket; 9. Electric motor; 10. Reducer; 11. Water vapor return pipe. Detailed Implementation

[0028] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0029] like Figures 1-5 As shown, the dryer in this embodiment includes a steam generator (not shown in the figure), a steam conveying pipe 1, a frame 2, a first cover plate 3, a second cover plate (not shown in the figure), an exhaust fan (not shown in the figure), a power unit, a mesh belt conveyor unit, a steam heating pipe, and a water vapor return pipe 11. The steam inlet at one end of the steam conveying pipe 1 is connected to the steam outlet of the steam generator. The frame 2 is a multi-layered rectangular frame structure. The upper part of the frame 2 is equipped with the first cover plate 3 (for easy display of the internal structure). Figure 1 and Figure 2Part of the first cover plate 3 was removed. An air inlet is left at the bottom of the frame 2. A second cover plate is installed at the top of the frame 2, with several air outlets on the second cover plate. Each air outlet is equipped with an exhaust fan, which is a continuously adjustable speed exhaust fan. Five layers of mesh belt conveyor units and steam heating pipes are installed vertically inside the frame 2. Below each layer of mesh belt conveyor unit is a uniformly arranged, rectangular layer of steam heating pipes. The mesh belts 4 of adjacent mesh belt conveyor units run in opposite directions, and the mesh belts of adjacent mesh belt conveyor units are in opposite directions. The conveyor belts are staggered, and the material falling from the unloading end of the upper layer of the mesh belt conveyor unit can fall onto the upper end of the mesh belt 4 of the lower layer of the mesh belt conveyor unit. The power unit is an electric motor 9 with a reducer 10. The power unit is installed at one end of the bottom of the frame 2. The power unit and the mesh belt conveyor unit are connected by a transmission assembly. The steam inlet of each layer of steam heating pipe is connected to the steam outlet of the steam conveying pipe 1. The water vapor outlet of each layer of steam heating pipe is connected to the water vapor inlet of the water vapor return pipe 11. The water vapor outlet of the water vapor return pipe 11 is connected to the return water port of the steam generator.

[0030] Preferably, the system also includes a steam filter, which is installed on the steam delivery pipe 1. The function of the steam filter is to intercept impurities (such as rust and welding slag) that may be mixed in with the steam, improve the purity of the steam, protect the downstream steam heating pipe and water vapor return pipe 11 from blockage or wear, make the heating system operate more stably, and reduce failures and energy consumption.

[0031] Preferably, the power unit consists of two electric motors 9 equipped with reducers 10. The transmission assembly includes a drive sprocket, a first-stage chain (not shown in the figure), a first-stage driven sprocket 8, and a second-stage chain (not shown in the figure). The first-stage driven sprocket 8 is a double sprocket. Each reducer 10 has a drive sprocket mounted on its power output shaft. Each of the mesh belt conveyor units has a first-stage driven sprocket 8 mounted at one end of its power input shaft. The two drive sprockets are each connected to the first-stage driven sprocket 8 of one of the two mesh belt conveyor units with opposite mesh belt running directions via a first-stage chain drive. The first-stage driven sprockets 8 of the mesh belt conveyor units with the same mesh belt running direction are connected via a second-stage chain drive.

[0032] Preferably, the mesh belt conveyor unit includes bearings, a power input shaft, a driven shaft, a first sprocket 6, a second sprocket 7, a first chain 5, and a mesh belt 4. The power input shaft is horizontally mounted at one end of the frame 2 along its length via bearings, and the driven shaft is horizontally mounted at the other end of the frame 2 along its length via bearings. The power input shaft and the driven shaft are parallel. A pair of first sprockets 6 are mounted on the power input shaft, and a pair of second sprockets 7 are mounted on the driven shaft. A first chain 5 is mounted at each end of the mesh belt 4 parallel to its running direction. The first chain 5 meshes with the first sprocket 6 and the second sprocket 7, and the first chain 5 is tensioned.

[0033] The steam heating pipe is a single layer of multi-turn right-angle rotating coil.

[0034] Both the steam delivery pipe 1 and the water vapor return pipe 11 include a vertical pipe and a horizontal pipe connected to the lower end of the vertical pipe. The vertical pipe of the steam delivery pipe 1 has five steam outlets at different heights, and the vertical pipe of the water vapor return pipe 11 has five water vapor inlets at different heights. The steam inlet of each layer of steam heating pipe is connected to the steam outlet at the corresponding height on the vertical pipe of the steam delivery pipe 1, and the water vapor outlet of each layer of steam heating pipe is connected to the water vapor inlet at the corresponding height on the vertical pipe of the water vapor return pipe 11.

[0035] Preferably, the exhaust fan is a continuously variable speed exhaust fan (achieved through a frequency converter or electronic speed controller) or an exhaust fan with thyristor speed regulation.

[0036] For ease of feeding, preferably, a feeding device is also included to move the material to be dried onto the mesh belt at the feeding end of the uppermost mesh belt conveyor unit. The feeding device can be a conveyor or any other suitable appliance for performing the feeding task. When the material to be dried is located above the dryer, the feeding device can be a hopper, which moves the material to be dried onto the mesh belt at the feeding end of the uppermost mesh belt conveyor unit.

[0037] Preferably, a material discharge device is provided below the discharge end of the lowest mesh belt conveyor unit to discharge the falling material from the frame.

[0038] Preferably, the material discharge device is a conveyor or an inclined guide trough.

[0039] The working principle of the dryer in this embodiment is as follows: Steam generated by the steam generator enters the steam heating pipe below each layer of mesh belt conveyor unit after passing through the steam conveying pipe 1 and the steam filter installed on it. At the same time, the Chinese medicinal materials to be dried are successively moved to the feeding end of the mesh belt 4 of the uppermost (i.e., the fifth layer) mesh belt conveyor unit through the feeding device. As the mesh belt 4 of the mesh belt conveyor unit moves, the Chinese medicinal materials that have moved to the feeding end of the uppermost mesh belt conveyor unit are moved from the feeding end to the unloading end and fall onto the feeding end of the next layer mesh belt conveyor unit. This process continues until the Chinese medicinal materials finally fall from the unloading end of the mesh belt 4 of the lowermost (i.e., the first layer) mesh belt conveyor unit. During this process, at the top of the frame 2 Under the action of the exhaust fan installed on the second cover plate, air flows in from the air inlet at the bottom of the frame 2, and flows sequentially through the bottom layer of steam heating pipes, the mesh of the bottom layer of mesh belt conveyor unit 4, the three middle layers of steam heating pipes and the mesh of the corresponding mesh belt conveyor units 4, the top layer of steam heating pipes, and the mesh of the top layer of mesh belt conveyor unit 4. As the air flows through the steam heating pipes, it is heated, and is heated once each time it flows through a layer of steam heating pipes. Simultaneously, the steam in the steam heating pipes is cooled into water vapor. When the (hot) air flows through the mesh of each layer of mesh belt conveyor unit 4, it heats the Chinese medicinal materials on that layer of mesh belt conveyor unit 4 and carries away the evaporated water vapor. Finally, the air flows through the top layer of mesh belt conveyor unit 4... Air and water vapor in the mesh of the conveyor belt 4 of the conveyor unit are drawn away and discharged by the exhaust fan. The medicinal herbs to be dried are dried once each time they pass through a conveyor belt unit from top to bottom, with their moisture content decreasing accordingly. The medicinal herbs that finally fall from the bottommost conveyor belt 4 are those that have met the drying requirements or have been dried to a certain extent. For medicinal herbs that have not yet met the drying requirements, they can be dried again according to the above drying process until they do. As the medicinal herbs move with the conveyor belt, the side of the herbs facing the conveyor belt is in direct contact with the upward-flowing hot air, resulting in faster moisture evaporation on that side and faster drying. The medicinal herbs to be dried are then conveyed from the upper conveyor belt... During the process of the herb falling from the feed end of the unit onto the feed end of the next layer of the mesh belt conveyor unit, the side with higher moisture content is heavier than the other side. Therefore, during the falling process, the herb flips over, and the side with higher moisture content remains facing down. Finally, after the herb falls onto the feed end of the next layer of the mesh belt conveyor unit and comes to a stop, the side with higher moisture content is facing down (in this state, the center of gravity of the herb is low and the stability is good). In this way, every time the herb to be dried falls from the feed end of the mesh belt of the previous layer of the mesh belt conveyor unit onto the feed end of the next layer of the mesh belt conveyor unit, the side with higher moisture content will always face the feed end of the next layer of the mesh belt conveyor unit, thereby achieving fast and uniform drying.The air and water vapor flowing through the lower-moisture-content medicinal herbs on the lower mesh belt conveyor unit 4 have residual heat that can be fully utilized as the airflow continues upward through the upper-moisture-content medicinal herbs on the upper mesh belt conveyor unit 4. Therefore, the dryer in this embodiment has the advantages of low heat loss, high energy utilization efficiency, and energy saving. Compared with drying methods using electric heating, using hot airflow generated by air flowing through uniformly arranged and rectangular steam heating pipes to dry the medicinal herbs moving with the mesh belt results in more uniform heating of the herbs, preventing localized heat accumulation and spontaneous combustion. By adjusting the speed of the exhaust fan, and if necessary, adjusting the heating power of the steam generator to adjust the steam generation speed or temperature, the speed of the airflow flowing through the steam heating pipes, the speed and temperature of the airflow flowing through the medicinal herbs to be dried, and the rate of moisture evaporation of the medicinal herbs can be easily adjusted, thereby meeting the different drying requirements of various medicinal herbs.

[0040] In this embodiment, the driving process of the mesh belt 4 of the mesh belt conveyor unit is as follows: one of the motors 9 drives the power input shaft of the lowest mesh belt conveyor unit to rotate through the reducer 10, the driving sprocket, the first-stage chain, and the first-stage driven sprocket 8, thereby driving the sprocket 6 on its power input shaft to rotate. The rotating sprocket 6 drives the mesh belt 4 to run through the chain 5 meshing with it, and at the same time drives the second sprocket 7 and the driven shaft to rotate. The first-stage driven sprocket 8 on the power input shaft of the third mesh belt conveyor unit is connected to the first-stage driven sprocket 8 on the power input shaft of the lowest mesh belt conveyor unit through the second-stage chain. The power input shaft of the uppermost (i.e., the fifth layer) mesh belt conveyor unit... The first-stage driven sprocket 8 on the input shaft is connected to the first-stage driven sprocket 8 on the power input shaft of the third-layer mesh belt conveyor unit via the second-stage chain. When the first-stage driven sprocket 8 on the power input shaft of the lowest-layer mesh belt conveyor unit rotates under the drive of the first-stage chain, the first-stage driven sprocket 8 on the power input shaft of the third-layer mesh belt conveyor unit and the first-stage driven sprocket 8 on the power input shaft of the highest-layer (i.e., fifth-layer) mesh belt conveyor unit also rotate synchronously and in the same direction under the drive of the second-stage chain, ultimately driving the mesh belt 4 of the lowest-layer mesh belt conveyor unit, the mesh belt 4 of the third-layer mesh belt conveyor unit, and the mesh belt 4 of the highest-layer mesh belt conveyor unit to run synchronously and in the same direction.

[0041] Another motor 9 drives the power input shaft of the second layer mesh belt conveyor unit to rotate via another reducer 10, another driving sprocket, another first-stage chain, and another first-stage driven sprocket 8. This drives the sprocket 6 on its power input shaft to rotate. The rotating sprocket 6 drives the mesh belt 4 through the chain 5 meshing with it, and simultaneously drives the sprocket 7 and driven shaft to rotate. The first-stage driven sprocket 8 on the power input shaft of the fourth layer mesh belt conveyor unit is connected to the first-stage driven sprocket 8 on the power input shaft of the second layer mesh belt conveyor unit through the second-stage chain. When the first-stage driven sprocket 8 on the power input shaft of the second layer mesh belt conveyor unit rotates under the drive of the other first-stage chain, the first-stage driven sprocket 8 on the power input shaft of the fourth layer mesh belt conveyor unit also rotates synchronously and in the same direction under the transmission of the second-stage chain. Finally, it drives the mesh belt 4 of the second layer mesh belt conveyor unit and the mesh belt 4 of the fourth layer mesh belt conveyor unit to run synchronously and in the same direction.

[0042] By rotating the power output shafts of the two opposing motors 9 or reducers 10 clockwise (i.e., clockwise when viewed from the front end of each power output shaft), the mesh belts 4 of the bottom layer mesh belt conveyor unit, the third layer mesh belt conveyor unit, and the top layer (i.e., the fifth layer) mesh belt conveyor unit can be made to run in the opposite direction to the mesh belts 4 of the second layer mesh belt conveyor unit and the fourth layer mesh belt conveyor unit, thus achieving opposite running directions of the mesh belts 4 of adjacent mesh belt conveyor units.

[0043] Obviously, the above embodiments are not the only implementations of this utility model. Many simple modifications can be made without departing from its technical essence. For example: the power unit can be installed on the second cover plate or at the working site of the dryer; the power unit can be two electric motors, each connected to one of two mesh belt conveyor units with opposite running directions, and mesh belt conveyor units with the same running direction can be connected; the power unit can be a single electric motor with a reducer, which has two power output shafts extending in the same direction but rotating in opposite directions, each connected to one of two mesh belt conveyor units with opposite running directions, and mesh belt conveyor units with the same running direction can be connected; the power unit can be three or more electric motors, each installed on the first cover plate, and each electric motor connected to one mesh belt conveyor unit via a coupling; the steam heating pipe can be a single layer of rectangular wave pipe, and so on, which will not be elaborated further here.

[0044] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Various changes made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present utility model should also be considered within the protection scope of the present utility model.

Claims

1. A dryer, characterized in that: The system includes a steam generator, steam delivery pipes, a frame, a first cover plate, a second cover plate, an exhaust fan, a power unit, a mesh belt conveyor unit, steam heating pipes, and a steam return pipe. One end of the steam delivery pipe has a steam inlet connected to the steam outlet of the steam generator. The frame is a multi-layered rectangular frame structure. The upper part of the frame has a first cover plate installed around its four sides. An air inlet is located at the lower part of the frame, and a second cover plate is installed at the top of the frame. The second cover plate has several air outlets, each equipped with an exhaust fan. The exhaust fan is a continuously adjustable speed exhaust fan. The frame contains three or more layers of mesh belt conveyor units and steam heating pipes installed vertically. Below each layer of mesh belt conveyor units is a uniformly arranged, rectangular layer of steam heating pipes. The mesh belts of two adjacent mesh belt conveyor units run in opposite directions, and the two ends of the mesh belts of the two adjacent mesh belt conveyor units are staggered at both ends in the running direction. The material falling from the unloading end of the upper mesh belt conveyor unit can fall onto the feeding end of the mesh belt of the lower mesh belt conveyor unit. The power device is an electric motor or an electric motor with a reducer. The power device is installed on the frame, the first cover plate, the second cover plate, or the working area of ​​the dryer. The power device and the mesh belt conveyor unit are connected by a transmission component. The steam inlet of each layer of steam heating pipe is connected to the steam outlet of the steam conveying pipe. The water vapor outlet of each layer of steam heating pipe is connected to the water vapor inlet of the water vapor return pipe. The water vapor outlet of the water vapor return pipe is connected to the return water port of the steam generator.

2. The dryer according to claim 1, characterized in that: It also includes a steam filter, which is installed on the steam delivery pipe.

3. The dryer according to claim 1, characterized in that: The power unit consists of two electric motors or two electric motors with reducers. Each of the two electric motors or reducers is connected to one of the two mesh belt conveyor units with opposite mesh belt running directions. Mesh belt conveyor units with the same mesh belt running direction are connected to each other.

4. The dryer according to claim 1, characterized in that: The power unit consists of two electric motors or two electric motors with reducers. The transmission assembly includes a drive sprocket, a first-stage chain, a first-stage driven sprocket, and a second-stage chain. The first-stage driven sprocket is a double sprocket. Each electric motor or reducer has a drive sprocket mounted on its power output shaft. Each mesh belt conveyor unit has a first-stage driven sprocket mounted at one end of its power input shaft. The two drive sprockets are each connected to the first-stage driven sprocket of one of the two mesh belt conveyor units with opposite mesh belt running directions via a first-stage chain drive. The first-stage driven sprockets of mesh belt conveyor units with the same mesh belt running direction are connected via a second-stage chain drive.

5. The dryer according to claim 1, characterized in that: The mesh belt conveyor unit includes bearings, a power input shaft, a driven shaft, a first sprocket, a second sprocket, a first chain, and a mesh belt. The power input shaft is horizontally mounted at one end of the frame along its length via bearings, and the driven shaft is horizontally mounted at the other end of the frame along its length via bearings. The power input shaft and the driven shaft are parallel. A pair of first sprockets are mounted on the power input shaft, and a pair of second sprockets are mounted on the driven shaft. A first chain is mounted at each end of the mesh belt parallel to its running direction. The first chain meshes with the first and second sprockets and is tensioned.

6. The dryer according to claim 1, characterized in that: The steam heating pipe is a single layer of multi-turn right-angle rotary coil or a single layer of rectangular wave tube.

7. The dryer according to claim 1, characterized in that: Both the steam delivery pipe and the water vapor return pipe include at least a vertical pipe. The vertical pipe of the steam delivery pipe has three or more steam outlets at different heights, and the vertical pipe of the water vapor return pipe has three or more water vapor inlets at different heights. The steam inlet of each layer of steam heating pipe is connected to the steam outlet at the corresponding height on the vertical pipe of the steam delivery pipe, and the water vapor outlet of each layer of steam heating pipe is connected to the water vapor inlet at the corresponding height on the vertical pipe of the water vapor return pipe.

8. The dryer according to claim 1, characterized in that: The exhaust fan is a continuously variable speed exhaust fan or an exhaust fan with a thyristor speed control.

9. The dryer according to claim 1, characterized in that: It also includes a feeding device for moving the material to be dried onto the feeding end of the uppermost mesh belt conveyor unit.

10. The dryer according to claim 1, characterized in that: Below the discharge end of the lowest mesh belt conveyor unit is a material discharge device for discharging the falling material from the frame.

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