Multi-layer self-cleaning mesh belt type drying machine

Abstract

The utility model discloses a multi-layer self-cleaning mesh belt type drying machine, and relates to the technical field of drying. The material conveying device comprises a plurality of material conveying mesh belts which are vertically arranged and arranged in a drying box, the discharging end of the upper material conveying mesh belt is arranged above the feeding side of the lower adjacent material conveying mesh belt, the feeding end of the material conveying mesh belt extends out of the drying box, a cleaning mechanism is arranged below the feeding end, and the cleaning mechanism is arranged below the feeding end of the material conveying mesh belt. The cleaning end of the cleaning mechanism is used for cleaning the lower mesh belt at the feeding end; the problems that an existing drying machine cannot clean a net belt on line, and net sticking materials are difficult to remove are solved.

Description

Technical Field

[0001] This utility model relates to the field of drying technology, specifically, a multi-layer self-cleaning mesh belt dryer. Background Technology

[0002] Multi-layer mesh belt dryers, as a type of continuous drying equipment, are widely used in agricultural product processing (such as dried fruit, aquatic products, Chinese medicinal herbs, and fruit pomace) due to their high capacity, high thermal efficiency, and compact footprint. However, existing equipment generally faces numerous technical bottlenecks in long-term operation when dealing with materials with high moisture, high sugar content, or viscous components.

[0003] In the early stages of drying, materials may adhere to the mesh belt surface due to the precipitation of free water or the melting of sugars, forming localized clumps. As the drying process progresses, sticky substances continue to deposit in the mesh belt pores, leading to a significant decrease in air permeability. This not only causes uneven heating of the material, affecting the consistency of the finished product's moisture content, but also forces frequent equipment shutdowns for manual mesh cleaning, severely restricting continuous production capacity.

[0004] For example, in applications requiring strict purity, such as traditional Chinese medicinal materials, traditional conveyor belt structures lack effective material isolation mechanisms. Trace components remaining in the pores of the conveyor belt (such as volatile oils and alkaloids) can easily migrate to subsequent batches of materials under high-temperature conditions, leading to mixing of herbs or cross-contamination of flavors. Existing technologies rely on high-pressure water rinsing or chemical cleaning after shutdown, which not only increases energy consumption but also raises concerns about secondary pollution due to cleaning agent residues.

[0005] The mechanical scraper screen cleaning solution commonly used in the industry has two major drawbacks: first, the contact between the rigid scraper and the mesh belt is prone to metal fatigue damage; second, it is not efficient at removing deep-seated deposits in micron-sized pores. Utility Model Content

[0006] The purpose of this invention is to provide a multi-layer self-cleaning mesh belt dryer to solve the problems of existing dryers being unable to clean the mesh belt online and the difficulty in removing materials stuck to the mesh.

[0007] To solve the above problems, the present invention adopts the following technical means:

[0008] A multi-layer self-cleaning mesh belt dryer includes several vertically arranged conveyor mesh belts disposed inside a drying chamber. The discharge end of the upper conveyor mesh belt is located above the feed side of the lower adjacent conveyor mesh belt. The feed end of the conveyor mesh belt extends out of the drying chamber. A cleaning mechanism is provided below the feed end, and the cleaning end of the cleaning mechanism is used to clean the lower mesh belt at the feed end.

[0009] Preferably, the conveyor belts are arranged horizontally and parallel to each other.

[0010] Furthermore, the side wall of the drying chamber is constructed with a through channel for the feed end of the conveyor belt to pass through, and an isolation sealing plate is installed in the through channel, the isolation sealing plate being located between the upper and lower mesh belts of the conveyor belt.

[0011] Furthermore, the drying chamber is equipped with a downward-sloping baffle, the inclined surface of which faces the discharge end of the conveyor belt.

[0012] Furthermore, the bottom end of the downward-sloping baffle is fitted to the top surface of the upper side of the conveyor belt, and a buffer zone is formed between the side of the downward-sloping baffle facing away from the discharge end and the inner wall of the drying chamber.

[0013] Furthermore, the cleaning mechanism includes a high-pressure nozzle, a brush, and a water tank with an open top surface;

[0014] The water spray end of the high-pressure nozzle is positioned facing the lower mesh belt of the feed end, the bristle side of the brush is in contact with the lower mesh belt of the feed end, and the water tank is located below the high-pressure nozzle and the brush.

[0015] Furthermore, the high-pressure nozzle is located between the upper and lower mesh belts of the conveyor belt, and the high-pressure nozzle is located on the upstream side of the brush.

[0016] Furthermore, the bottom surface of the brush is located below the liquid level in the water tank.

[0017] Furthermore, the cleaning mechanism also includes a cold shrinkage box and a thermal expansion box, which are arranged sequentially along the conveyor belt's moving direction.

[0018] The lower conveyor belt passes sequentially through the cold shrink box and the thermal expansion box. The cold shrink box is used to cool the lower conveyor belt, and the inner cavity of the thermal expansion box is connected to the humid and hot gas exhaust end of the drying box. The thermal expansion box is used to heat and humidify the lower conveyor belt.

[0019] Furthermore, the cold shrink box includes a first heat-insulating box with openings at both ends for the lower mesh belt to pass through. The top of the first heat-insulating box has a cavity for holding dry ice. The cavity is located above the lower mesh belt, and the bottom surface of the cavity has a through-hole for pipe penetration.

[0020] The thermal expansion box includes a second heat insulation box with openings at both ends for the lower mesh belt to pass through. The bottom surface of the second heat insulation box is connected to an air inlet pipe that is connected to the exhaust end of the hot and humid gas, and the top surface of the second heat insulation box is connected to an exhaust pipe.

[0021] The present invention has the following beneficial effects during use:

[0022] Material gradually falls downwards from the top conveyor belt inside the drying chamber, drying along the conveyor belt from top to bottom. The material moves in S-shaped segments as the conveyor belt moves, finally exiting from the bottom conveyor belt. Each conveyor belt's upper belt is used to transport material, from the upper conveyor belt to the lower conveyor belt, until it is unloaded from the drying chamber. As the conveyor belt moves, after completing material transport, the upper belt becomes the lower conveyor belt. The lower conveyor belt moves from the discharge end to the feed end. Because the feed end of the conveyor belt and the cleaning mechanism are located outside the drying chamber, and the cleaning mechanism is used to clean the lower conveyor belt, the cleaned lower conveyor belt, as it moves, becomes the upper belt again. The cleaned upper conveyor belt can then enter the drying chamber from outside to receive material falling from the upper conveyor belt, ensuring the normal operation of the drying process. In this way, the drying operation is carried out inside the drying chamber, while the cleaning operation is carried out independently outside the drying chamber. This allows the system to clean the conveyor belt online while drying, achieving the effect of cleaning and drying simultaneously. This avoids the adhesion and accumulation of materials during the drying process and ensures the ventilation of the conveyor belt at all times, thus ensuring the effectiveness of the drying operation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model.

[0024] Figure 2 This is a schematic diagram of the cold shrink box structure in one embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the thermal expansion box structure in one embodiment of the present invention.

[0026] Among them, 1-drying box, 2-conveying mesh belt, 3-discharge end, 4-feeding end, 5-cleaning mechanism, 6-isolation sealing plate, 7-downward baffle, 8-buffer zone, 9-high pressure nozzle, 10-brush, 11-water tank, 12-cold shrinkage box, 13-thermal expansion box, 14-first heat insulation box, 15-accommodating cavity, 16-through port, 17-second heat insulation box, 18-air inlet pipe, 19-exhaust pipe. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] Please refer to Figure 1 As shown, a multi-layer self-cleaning mesh belt dryer includes several vertically arranged conveyor belts 2 located inside a drying chamber 1. The feed end 4 of the uppermost conveyor belt 2 serves as the feed side of the dryer, where the material to be dried falls from the feeder and enters the drying chamber 1. The discharge end 3 of the lowermost conveyor belt 2 serves as the discharge side of the dryer, where the material falling from the lowermost conveyor belt 2 falls into the discharge conveyor and is then sent out of the drying chamber 1 by the discharge conveyor.

[0034] The discharge end 3 of the conveyor belt 2 is located above the feed side of the adjacent conveyor belt 2 below, and the conveyor belts 2 are arranged horizontally and parallel to each other. Here, the discharge end 3 refers to the end where the material falls off the conveyor belt 2 as it is conveyed along the conveyor belt 2, while the feed side is the side of the conveyor belt 2 closest to the feed end 4; thus, after the material enters the drying chamber 1, it continuously falls from the upper conveyor belt 2 to the lower conveyor belt 2 along the conveying direction of the conveyor belt 2, so that the material moves in an S-shaped segment within the drying chamber 1 as the conveyor belts 2 run.

[0035] Furthermore, the feed end 4 of the conveyor belt 2 extends out of the drying box 1, and a cleaning mechanism 5 is provided below the feed end 4. The cleaning end of the cleaning mechanism 5 is used to clean the lower conveyor belt of the feed end 4.

[0036] In this way, the material gradually falls downwards from the top conveyor belt 2 inside the drying chamber 1. The material is dried from top to bottom along the conveyor belt 2, moving in an S-shaped segment as it travels within the drying chamber 1, and finally exits from the bottom conveyor belt. Each conveyor belt 2 has a top belt for transporting material, which is conveyed from the top belt of the upper conveyor belt 2 to the top belt of the lower conveyor belt 2 until it is unloaded from the drying chamber 1. As the conveyor belt 2 continues to move, after completing the material transport, the top belt transitions into the lower conveyor belt. The lower conveyor belt moves from the discharge end 3 to the feed end 4. Because the feed end 4 of the conveyor belt 2 and the cleaning mechanism 5 are located outside the drying chamber 1, and the cleaning mechanism 5 is used to clean the lower conveyor belt, the cleaned lower conveyor belt is transferred back to the upper conveyor belt as it moves. The cleaned upper conveyor belt can then enter the drying chamber 1 from outside as the conveyor belt 2 runs, catching the material falling from the upper conveyor belt 2 and ensuring the normal operation of the drying process. In this way, the drying operation takes place inside the drying chamber 1, while the cleaning operation is carried out independently outside the drying chamber 1. This allows the system to clean the conveyor belt online while drying, achieving the effect of simultaneous cleaning and drying. This avoids the adhesion and accumulation of materials during the drying process and ensures the ventilation of the conveyor belt 2 at all times, guaranteeing the effectiveness of the drying operation.

[0037] In addition, the side wall of the drying chamber 1 is constructed with a through channel for the feed end 4 of the conveyor belt 2 to pass through, allowing the feed end 4 of the conveyor belt 2 to extend smoothly out of the drying chamber 1. To prevent liquid generated by the cleaning mechanism 5 during the cleaning of the conveyor belt from splashing into the drying chamber 1, an isolation sealing plate 6 is installed in the through channel. The isolation sealing plate 6 is located between the upper and lower mesh belts of the conveyor belt 2. Thus, the isolation sealing plate 6 seals the through channel, leaving only a gap for the upper and lower mesh belts of the conveyor belt 2 to pass through, and also ensuring that the temperature inside the drying chamber 1 does not fluctuate significantly.

[0038] Furthermore, the drying chamber 1 is equipped with a downward-sloping baffle 7, the inclined surface of which faces the discharge end 3 of the conveyor belt 2.

[0039] The downward-sloping baffle 7 is designed to prevent materials from hitting the inner wall of the drying chamber 1 due to inertia as they fall from the upper conveyor belt 2 to the lower conveyor belt 2.

[0040] Meanwhile, the bottom end of the downward-sloping baffle 7 is fitted to the top surface of the upper side of the conveyor belt 2, and a buffer zone 8 is formed between the side of the downward-sloping baffle 7 facing away from the discharge end 3 and the inner wall of the drying box 1.

[0041] Thus, with the downward-sloping baffle 7 installed, the material falling from the upper conveyor belt 2 into the lower conveyor belt 2 can strike the downward-sloping baffle 7 and then slide down the inclined surface of the downward-sloping baffle 7 onto the lower conveyor belt 2. This ensures that when the material contacts the upper conveyor belt 2, it is kept away from the side wall of the drying chamber 1, i.e., away from the aforementioned through-channel. Furthermore, after cleaning, when the conveyor belt enters the drying chamber 1, before contacting the falling material, the conveyor belt moves within the buffer zone 8 between the inner wall of the drying chamber 1 and the downward-sloping baffle 7. This allows the conveyor belt to preheat and dry using the heat within the drying chamber 1 while moving within the buffer zone 8, preventing the conveyor belt from retaining a large amount of liquid generated by the cleaning mechanism 5 during cleaning.

[0042] Furthermore, by utilizing the close fit between the bottom end of the downward-sloping baffle 7 and the mesh belt, for some large but small droplets remaining on the mesh belt, the downward-sloping baffle 7 can scrape away this part of the liquid that has not dried in the aforementioned buffer zone 8. On the one hand, by scraping and blocking, it prevents the droplets from contacting the material falling from above through the downward-sloping baffle 7; on the other hand, by flattening, it increases the contact area between the droplets and the mesh belt, increases the heating area, and thus accelerates the drying process.

[0043] Therefore, by setting up the downward-sloping baffle 7, it is possible to effectively prevent the liquid remaining on the mesh belt outside the drying chamber 1 from the cleaning mechanism 5 during the online cleaning process from affecting the dried material. This ensures that online drying will not affect the drying process of the material.

[0044] As for the cleaning mechanism 5, the cleaning mechanism 5 includes a high-pressure nozzle 9, a brush 10 and a water tank 11 with an open top surface;

[0045] The water spray end of the high-pressure nozzle 9 is positioned towards the lower mesh belt of the feed end 4, the bristle side of the brush 10 is in contact with the lower mesh belt of the feed end 4, and the water tank 11 is located below the high-pressure nozzle 9 and the brush 10.

[0046] Meanwhile, the high-pressure nozzle 9 is located between the upper and lower mesh belts of the conveyor belt 2, and the high-pressure nozzle 9 is located on the upstream side of the brush 10.

[0047] Thus, during the cleaning process of the conveyor belt, the high-pressure nozzle 9 is first used to spray water to rinse the material adhering to the conveyor belt, preparing for the scraping and cleaning by the brush 10; then the brush 10 is used to scrape off the material adhering to the conveyor belt, and the water tank 11 is used to spray water and scrape off the residue.

[0048] The brush 10 rotates in the opposite direction to the mesh belt, thereby enhancing the cleaning effect of the brush 10 on the mesh belt.

[0049] Furthermore, the bottom surface of the brush 10 is located below the liquid level in the water tank 11.

[0050] In this way, not only can the liquid in the water tank 11 be used to clean the brush 10 after cleaning, avoiding a large amount of residue remaining on the brush 10, but the brush 10 can also carry the cleaning liquid, making the brush 10 clean the mesh belt more thoroughly.

[0051] In this preferred embodiment, based on the foregoing description, please refer to... Figure 2 and Figure 3 As shown, the cleaning mechanism 5 also includes a cold shrinkage box 12 and a thermal expansion box 13, which are arranged sequentially along the conveyor belt 2.

[0052] The lower conveyor belt 2 passes sequentially through the cold shrink box 12 and the thermal expansion box 13. The cold shrink box 12 is used to cool the lower conveyor belt. The inner cavity of the thermal expansion box 13 is connected to the humid and hot gas exhaust end of the drying box 1. The thermal expansion box 13 is used to heat and humidify the lower conveyor belt.

[0053] Before the high-pressure nozzle 9 acts on the mesh belt, the mesh belt passes through the cold shrink box 12 and the thermal expansion box 13 in sequence.

[0054] For the cold shrink chamber 12, it is used to cool the mesh belt. When the mesh belt passes through the cold shrink chamber 12, the mesh belt, which was originally heated in the drying chamber 1, is rapidly cooled. On the one hand, this reduces the temperature of the mesh belt, preparing it for subsequent operations in the thermal expansion chamber 13. On the other hand, after the mesh belt is rapidly cooled in the cold shrink chamber 12, it can shrink due to the thermal expansion and contraction properties of the metal mesh belt. In this way, for some of the material embedded in the mesh, the embedded material itself has a low moisture content and is relatively brittle. When the mesh belt shrinks rapidly due to cooling, the mesh also shrinks. This shrinkage of the mesh then applies a slight compression to the dried material embedded in the mesh, causing some cracks to appear on the surface or inside of the embedded dried material. Combined with the subsequent thermal expansion chamber 13, this reduces the embedding effect between the material embedded in the mesh and the mesh, thus facilitating the subsequent high-pressure nozzle 9 to flush the material in the mesh.

[0055] For the thermal expansion chamber 13, it is used to heat the mesh belt. The heat source for heating the mesh belt in the thermal expansion chamber 13 comes from the high-temperature and humid gas discharged from the drying chamber 1. This heat source not only enables energy recovery, but more importantly, it not only heats the mesh belt, but also allows the large amount of moisture carried in the gas to condense on the surface of the mesh belt after contacting it with the mesh belt cooled by the cold contraction chamber 12. This results in a liquid film covering the surface of the mesh belt. Furthermore, by setting up the thermal expansion box 13, on the one hand, the cooled and shrunken mesh belt is heated, causing it to expand and the mesh holes to expand as well. The material trapped in the mesh holes remains in its original shape. After the material is squeezed and partially cracked, the expansion of the mesh holes reduces the squeezing effect between the mesh holes and the embedded material, thus loosening the material inside the mesh holes. This allows the material embedded in the mesh holes to be better removed from the mesh holes when sprayed by the high-pressure nozzle 9, thereby improving the cleaning efficiency of the mesh holes. On the other hand, the condensate film covering the surface of the mesh belt can soak the material adhering to the mesh belt, reducing the adhesion between the material and the mesh belt. This makes it easier to clean the material adhering to the surface of the material using the brush 10, thereby improving the cleaning effect of the brush 10.

[0056] More specifically, for the cold shrink box 12, the cold shrink box 12 includes a first heat insulation box 14 with openings at both ends for the lower mesh belt to pass through. The inner top of the first heat insulation box 14 is provided with a receiving cavity 15 for placing dry ice. The receiving cavity 15 is located above the lower mesh belt. The bottom surface of the receiving cavity 15 is provided with a through port 16 for passing through a pipe.

[0057] By placing dry ice in the containment cavity 15, since the density of dry ice is greater than that of air, the sublimation of dry ice can not only absorb heat to cool the inside of the cold shrink chamber 12, but also allow the lower temperature gas after sublimation to fall through the through port 16 and then come into contact with the mesh belt passing through the cold shrink chamber 12, further cooling the mesh belt.

[0058] As for the thermal expansion box 13, the thermal expansion box 13 includes a second heat insulation box 17 with two ends configured for the lower mesh belt to pass through the opening. The bottom surface of the second heat insulation box 17 is connected to an air inlet pipe 18 that is connected to the exhaust end of the hot and humid gas, and the top surface of the second heat insulation box 17 is connected to an exhaust pipe 19.

[0059] In this way, by supplying air from bottom to top, the mesh belt passing through the thermal expansion box 13 can better contact the high-temperature and humid gas, which facilitates the formation of a liquid film on the surface of the mesh belt and allows the mesh belt to be well heated.

[0060] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-tiered self-cleaning mesh belt dryer characterized by, The utility model provides a kind of drying oven, including vertically arranged and be located in several material conveying mesh belt (2) of drying oven (1), the discharge end (3) of upper material conveying mesh belt (2) is located in the feeding side of lower adjacent material conveying mesh belt (2) above, the feeding end (4) of material conveying mesh belt (2) is stretched out drying oven (1), the lower side of feeding end (4) is provided with cleaning mechanism (5), and the cleaning end of cleaning mechanism (5) is used to clean the lower mesh belt of feeding end (4).

2. A multi-stage self-cleaning mesh belt dryer according to claim 1, characterized in that, The side wall of the drying oven (1) is provided with a through channel for the feeding end (4) of the material conveying mesh belt (2) to pass through, and an isolation sealing plate (6) is installed in the through channel. The isolation sealing plate (6) is arranged between the upper mesh belt and the lower mesh belt of the material conveying mesh belt (2).

3. A multi-stage self-cleaning mesh belt dryer according to any one of claims 1 or 2, characterized in that, The drying oven (1) is provided with a downward inclined baffle (7), and the inclined surface of the downward inclined baffle (7) faces the discharge end (3) of the material conveying mesh belt (2).

4. A multi-stage self-cleaning mesh belt dryer according to claim 3, characterized in that The bottom end of the downward inclined baffle (7) is arranged in close contact with the top surface of the upper mesh belt of the material conveying mesh belt (2), and a buffer zone (8) is formed between the side of the downward inclined baffle (7) facing away from the discharge end (3) and the inner wall of the drying oven (1).

5. A multi-stage self-cleaning mesh belt dryer according to claim 1, characterized in that, The cleaning mechanism (5) includes a high-pressure spray head (9), a brush (10), and a water tank (11) with an open top surface. The water spraying end of the high-pressure spray head (9) is arranged towards the lower mesh belt of the feeding end (4), the bristle side of the brush (10) is arranged in contact with the lower mesh belt of the feeding end (4), and the water tank (11) is arranged below the high-pressure spray head (9) and the brush (10).

6. A multi-stage self-cleaning mesh belt dryer according to claim 5, characterized in that The high-pressure spray head (9) is arranged between the upper mesh belt and the lower mesh belt of the material conveying mesh belt (2), and the high-pressure spray head (9) is arranged on the upstream side of the brush (10).

7. A multi-stage self-cleaning mesh belt dryer according to claim 5 or 6, characterized in that The bottom surface of the brush (10) is arranged below the liquid level in the water tank (11).

8. A multi-stage self-cleaning mesh belt dryer according to claim 5, characterized in that, The cleaning mechanism (5) further includes a cold contraction box (12) and a thermal expansion box (13), which are arranged in sequence along the mesh belt moving direction of the material conveying mesh belt (2). The lower mesh belt of the material conveying mesh belt (2) sequentially passes through the cold contraction box (12) and the thermal expansion box (13), the cold contraction box (12) is used for cooling the lower mesh belt, and the inner cavity of the thermal expansion box (13) is in communication with the wet hot gas exhaust end of the drying oven (1), and the thermal expansion box (13) is used for heating and humidifying the lower mesh belt.

9. A multi-stage self-cleaning mesh belt dryer according to claim 8, characterized in that The cold contraction box (12) includes a first heat insulation box (14) having through openings at both ends for the lower mesh belt to pass through, an accommodating cavity (15) for placing dry ice is formed at the inner top of the first heat insulation box (14), the accommodating cavity (15) is arranged above the lower mesh belt, and a through opening (16) for a pipe is formed at the bottom surface of the accommodating cavity (15).

10. A multi-stage self-cleaning mesh belt dryer according to claim 8, characterized in that The thermal expansion box (13) includes a second heat insulation box (17) having through openings at both ends for the lower mesh belt to pass through, an air inlet pipe (18) in communication with the wet hot gas exhaust end is communicated with the bottom surface of the second heat insulation box (17), and an air outlet pipe (19) is communicated with the top surface of the second heat insulation box (17).

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