A double conveyor tunnel furnace

Abstract

The present application relates to the field of uniform and efficient material processing, and in particular to a double conveyor belt tunnel furnace, comprising a processing chamber, a lower conveyor belt and a material to be processed, part of which is located inside the processing chamber. The lower conveyor belt drives the material to be processed to move in the Z direction or in the -Z direction. It also includes an upper conveyor belt, part of which is located inside the processing chamber and part of which is located above the upper surface of the material to be processed in the Y direction. The upper conveyor belt is used to prevent part of the material to be processed from being lifted and colliding or rubbing against the inner surface of the top of the processing chamber, while also removing the water vapor generated in the processing chamber. This processing device can be used in the field of uniform and efficient material processing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of uniform and efficient material processing, and in particular to a double conveyor belt tunnel furnace. BACKGROUND

[0002] Heating is an indispensable production process in industrial and agricultural production. A tunnel furnace is a continuous material processing equipment, which includes at least one conveyor belt, a processing chamber and a material to be processed. The conveyor belt passes through the processing chamber to send the material to be processed into the processing chamber. After the material is processed in the processing chamber, such as heating, drying, curing, sterilization, etc., it is sent out of the processing chamber by the conveyor belt.

[0003] The energy source of a common tunnel furnace can be natural gas, biofuel and electricity, etc. A microwave tunnel furnace feeds microwaves into the processing chamber to take advantage of the overall, rapid and selective processing of microwaves to process the material.

[0004] In various tunnel furnaces, the material to be processed often releases water vapor with a temperature higher than the ambient temperature when it is processed in the processing chamber. These relatively hot water vapor moves upward and condenses into water droplets when it hits the relatively cold top of the processing chamber, and then drips onto the material to be processed. One solution to this problem is to arrange infrared heating lamp tubes inside the processing chamber. These lamp tubes occupy a certain space in the processing chamber and consume a certain amount of energy, resulting in an increase in the manufacturing cost of the tunnel furnace and a decrease in energy efficiency. SUMMARY

[0005] The purpose of the present application is to provide a tunnel furnace. Specifically, it is a high energy efficient tunnel furnace with an upper conveyor belt and an upper conveyor belt.

[0006] A double conveyor belt tunnel furnace includes a processing chamber, a lower conveyor belt above the upper surface of the bottom of the processing chamber along the -Y direction, and an upper conveyor belt below the lower surface of the top of the processing chamber along the Y direction and above the upper surface of the lower conveyor belt. A gap for accommodating the material to be processed is provided between the upper conveyor belt and the lower conveyor belt. An X direction and a Z direction are also provided, and the X, Y and Z directions form an orthogonal coordinate system. The upper conveyor belt is a mesh structure belt with a plurality of water vapor permeable water droplet blocking mesh holes.

[0007] The water vapor permeable water droplet blocking mesh holes are A type mesh holes or the water vapor permeable water droplet blocking mesh holes are A1 type mesh holes and A2 type mesh holes.

[0008] The maximum transverse dimension of the A type mesh holes, A1 type mesh holes and A2 type mesh holes is less than or equal to 5 mm.

[0009] The maximum transverse dimension of the A type mesh holes, A1 type mesh holes and A2 type mesh holes is 1 mm or 2 mm or 3 mm or 4 mm.

[0010] The maximum lateral dimension of the A1 type of mesh is greater than the maximum lateral dimension of the A2 type of mesh.

[0011] The A1 type of mesh and the A2 type of mesh are arranged at intervals.

[0012] Further comprising at least one microwave feed opening located on the bottom and / or on the top, and at least one microwave source connected to the microwave feed opening.

[0013] The upper conveyor belt surrounds the top and forms a loop, or the upper conveyor belt forms a loop and is stacked in the processing chamber. The lowest surface of the inner portion of the upper conveyor belt moves in the direction of movement of the highest surface of the inner portion of the lower conveyor belt.

[0014] The so-called lowest surface or highest surface of the conveyor belt herein is generally a spatial surface, which is the upper surface or lower surface of the conveyor belt, and in special cases can be approximated as a portion of a plane.

[0015] At least one water trap is arranged at a distance of less than 100 mm from the inner surface or outer surface of the annular upper conveyor belt outside the processing chamber.

[0016] At least one water trap is arranged at a distance of less than 10 mm from the inner surface or outer surface of the annular upper conveyor belt outside the processing chamber.

[0017] In order to prevent the partial upper conveyor belt from being damaged due to staying in the processing chamber for too long, the partial upper conveyor belt above the processed material moves in the same direction as the partial lower conveyor belt below the processed material. Preferably, the speed of the partial upper conveyor belt above the processed material moving in the same direction as the partial lower conveyor belt below the processed material is similar or identical. Specifically, the upper conveyor belt and the lower conveyor belt move in the same direction, and the processed material is clamped and moved in the same direction by the upper conveyor belt and the lower conveyor belt.

[0018] In order to move the upper conveyor belt and the lower conveyor belt, the two conveyor belts are generally arranged in an annular manner with the first end connected to the second end. The two conveyor belts are partially located in the processing chamber. Each conveyor belt surrounds at least two rotating shafts. In a common case, each conveyor belt surrounds at least four rotating shafts. A portion of the surface of each conveyor belt is in contact with a portion of the cylindrical surface of the rotating shafts surrounded by the annular conveyor belt.

[0019] The apparatus can be a microwave tunnel furnace: the apparatus comprises at least one microwave feed port on the top portion, and a microwave source connected to the at least one microwave feed port. Preferably, there is one microwave source connected to each microwave feed port. The microwave feed ports can be located on the top portion or the bottom portion of the processing chamber, or some on the top portion and some on the bottom portion. The microwave source radiates microwave energy into the processing chamber through the microwave feed ports. Of course, the apparatus can also be any other type of tunnel furnace.

[0020] When the apparatus is in operation, the material to be processed enters the gap between the upper conveyor belt and the lower conveyor belt. The lower conveyor belt moves the material to be processed in the Z direction or in the -Z direction. Here, the processing chamber is generally a two-ended open tunnel structure with a top portion, a bottom portion, and two side portions.

[0021] In a microwave tunnel furnace, we call the processing chamber in which the microwaves are fed from the top portion a top-fed processing chamber, and the processing chamber in which the microwaves are fed from the bottom portion a bottom-fed processing chamber. For ease of expression, we construct a coordinate system with a point in the processing chamber as the origin, and the bottom portion generally in the -Y direction and the top portion generally in the Y direction. We set the direction of movement of the lower conveyor belt as the Z direction, and the direction perpendicular to the YZ plane as the X direction.

[0022] The design concept of the present technical solution is to add an upper conveyor belt above the lower conveyor belt on the basis of the existing processing chamber, so as to isolate the material to be processed from the lower surface of the top portion of the processing chamber. In general, the upper conveyor belt can be set as a loop like the lower conveyor belt. Specifically, the upper conveyor belt moves in the Z direction in the processing chamber. There can be some loading body on the top portion of the processing chamber. The upper conveyor belt prevents the material to be processed from being lifted and colliding with or rubbing against the inner surface of the top portion of the processing chamber in the Y direction or the loading body on the inner surface, so as to affect the smooth passage of the material to be processed through the processing chamber. At the same time, the upper conveyor belt can take out the water vapor generated in the processing chamber, preventing water droplets from forming on the bottom surface of the top portion of the processing chamber and falling onto the material to be processed. Thirdly, in a microwave tunnel furnace, the upper conveyor belt can also improve the uniformity of the processing of the material to be processed.

[0023] In order to improve the energy efficiency of the apparatus, it is beneficial to use thicker material to be processed. A new type of microwave tunnel furnace uses a relatively short processing chamber. However, the relatively short processing chamber leads to collision or friction between the thicker material to be processed and the upper inner surface of the processing chamber or the loading body on the upper inner surface of the processing chamber. The arrangement of the upper conveyor belt can well solve this problem.

[0024] The upper conveyor belt can efficiently carry the water vapor generated by the material being processed in the processing chamber out of the processing chamber and be eliminated by the water eliminator. Otherwise, the water vapor will condense on the lower surface of the top of the processing chamber and drip onto the material being processed.

[0025] In order to maximize the thickness of the material being processed, the upper conveyor belt can be made to move in the processing chamber together with the material being processed and the lower conveyor belt. Preferably, the upper conveyor belt is made to move in the processing chamber synchronously with the material being processed and the lower conveyor belt.

[0026] In order to facilitate the elimination of the water vapor generated in the processing chamber, the material of the upper conveyor belt is made of a mesh medium material, such as gauze, polyethylene mesh, etc. In special cases, the upper conveyor belt can also be made of metal wires.

[0027] In general, the mesh size of the mesh upper conveyor belt should be as large as possible to facilitate the emission of the steam generated by heating, but also small enough to prevent the heated material from passing through the upper conveyor belt.

[0028] The outer shape of the upper conveyor belt is generally a ring-shaped belt. The wide edge of the belt is along the X direction. The width of the belt-shaped upper conveyor belt is equal to or less than the internal width of the processing chamber.

[0029] In order to realize the movement of the lower conveyor belt in the processing chamber during the operation of the double-conveyor belt tunnel furnace, the lower conveyor belt surrounds the bottom of the processing chamber and forms a loop. In general, the loop-shaped lower conveyor belt passes through at least two rotating shafts located outside the processing chamber, at least one of which is a driving rotating shaft driven by external power.

[0030] The lower conveyor belt can also be loop-shaped, but overlaps inside the processing chamber. The two layers of lower conveyor belts located in the processing chamber move in opposite directions. The upper layer of lower conveyor belt drives the material being processed to move in the Z direction.

[0031] The upper conveyor belt can also be loop-shaped, but overlaps inside the processing chamber. The lower layer of upper conveyor belt drives the material being processed to move in the Z direction together with the upper layer of lower conveyor belt.

[0032] In general, the lower conveyor belt forming a loop is made of a medium material. In special cases, the lower conveyor belt can also be made of metal wires.

[0033] For a microwave tunnel furnace, the microwave feed ports are arranged on the bottom of the processing chamber, and can also be arranged on the top of the processing chamber as needed. The internal height of the processing chamber is less than the wavelength of the microwave. Preferably, the internal height of the processing chamber is less than half of the wavelength of the microwave.

[0034] To remove the water vapor carried by the conveying belt, at least one water remover is arranged at a certain distance from the inner surface or the outer surface of the annular conveying belt outside the processing chamber. The water remover is any structure or device that can remove water vapor from the conveying belt. For example, the water remover can be an axial flow fan that blows air from the inside to the outside of the annular conveying belt to dry the water vapor on the conveying belt, or sucks the water vapor on the conveying belt from the outside of the annular conveying belt. The water remover can also be a dryer that bakes the conveying belt at high temperature. The water remover can also be a hygroscopic material such as a sponge. The water remover can also be a roller brush that brushes off the water vapor on the conveying belt and directs the water vapor out of the device through a flow guide structure.

[0035] The water remover should be arranged as close to the conveying belt as possible without interfering with the movement of the conveying belt and minimizing the friction on the conveying belt. For example, at least one water remover is arranged at a distance of less than 100 mm from the inner surface or the outer surface of the annular conveying belt outside the processing chamber. Alternatively, at least one water remover is arranged at a distance of less than 10 mm from the inner surface or the outer surface of the annular conveying belt outside the processing chamber.

[0036] To facilitate the use of an air extractor to extract the water vapor generated in the processing chamber outside the processing chamber, the material of the conveying belt is a mesh medium material.

[0037] The selection of the mesh holes on the conveying belt is critical. The use of mesh conveying belt is beneficial to the removal of water vapor in the processing chamber, but may cause the treated material to pass through the conveying belt. We tend to use small-pore mesh conveying belt as much as possible under the condition of ensuring the removal of water vapor in the processing chamber. Therefore, at least 50% of the mesh holes on the conveying belt have a maximum transverse dimension of less than 10 mm, or less than 3 mm, or less than 1 mm, or less than 0.1 mm.

[0038] It should be particularly noted that:

[0039] The core technical problems to be solved by the present application are two:

[0040] First, due to the possibility of the treated material being raised, to prevent the raised treated material from colliding or rubbing with the metal load inside the processing chamber, the present application conceives a double conveying belt, which allows the upper conveying belt and the lower conveying belt to pass through the processing chamber, and the gap between the two is only large enough to accommodate the thickness of the treated material. The upper conveying belt and the lower conveying belt move in the same direction, so that the treated material is clamped and moves in the same direction with the conveying belt.

[0041] Second: The processed material will overflow steam after heating. The overflow steam will pass through the upper conveyor belt. Since the microwave heating is the processed material itself heating, the temperature in the processing cavity is low, and the overflow steam will condense into water droplets on the top of the processing cavity. The water droplets will drop onto the processed material. In order to prevent the condensation of water droplets from falling onto the processed material, the upper conveyor belt of the present application is improved, and the mesh is arranged on the upper conveyor belt. The mesh has the function of water vapor permeation and water droplet blocking. The mesh has the effect of allowing water vapor to pass upward and blocking water droplets from falling downward.

[0042] In order to set the mesh with the function of water vapor permeation and water droplet blocking, the present application provides two ways to achieve:

[0043] Method one: The mesh of the upper conveyor belt is only one type of mesh, that is, A type mesh. The size of the A type mesh is set to the purpose of preventing water droplets from passing through the upper conveyor belt. Since water droplets have tension, when the size of the A type mesh is small enough, the passage of water droplets can be prevented. Since there is only A type mesh, the mesh serves as a water vapor permeation mesh and a water droplet blocking mesh, and one mesh has two functions.

[0044] Method two: The mesh of the upper conveyor belt includes two types of mesh, that is, A1 type mesh and A2 type mesh, that is, a dedicated A1 type mesh for water vapor permeation and an A2 type mesh for water droplet blocking. The two types of mesh have independent functions, and the size of the A1 type mesh is larger than that of the A2 type mesh. Compared with method one, the water vapor permeation efficiency is increased. Since water droplet dripping is a random event, although there is a probability of passing through the A1 type mesh and falling onto the processed material, the probability is very small in this method. For example: 1 water vapor permeation A1 type mesh is taken as the center, and four directions are A2 type mesh for water droplet blocking, that is, two types of mesh are arranged and spaced according to point arrangement. For another example, the water vapor permeation A1 type mesh is arranged on both sides of the conveying direction of the conveyor belt, and the water droplet blocking A2 type mesh is arranged in the middle of the water vapor permeation A1 type mesh, that is, two types of mesh are arranged and spaced according to line arrangement.

[0045] The present application provides a double-conveyor belt tunnel furnace, which comprises a processing cavity, a lower conveyor belt for processed material in the processing cavity, and the lower conveyor belt drives the processed material to move in the Z direction or in the -Z direction. The upper conveyor belt is arranged above the upper surface of the processed material in the Y direction, which can prevent the processed material from being in conflict or friction with the top inner surface of the processing cavity or the metal loading body, and can also take out the water vapor generated in the processing cavity. This processing device can be used in the field of uniform high-energy efficiency material processing. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is the first side view of the present application.

[0047] Figure 2 Figure 2 is a second side view of the present application.

[0048] Figure 3 Figure 3 is a third side view of the present application.

[0049] Figure 4 Figure 4 is a first mesh pattern of the upper conveyor belt.

[0050] Figure 5 Figure 5 is a second mesh pattern of the upper conveyor belt.

[0051] Figure 6 Figure 6 is a third mesh pattern of the upper conveyor belt.

[0052] Figure 7 Figure 7 is a fourth mesh pattern of the upper conveyor belt.

[0053] Correspondence between reference numbers and names in the drawings: 1 - processing chamber, 11 - bottom, 12 - top, 2 - material to be processed, 3 - lower conveyor belt, 31 - lower conveyor belt rotation shaft, 4 - upper conveyor belt, 41 - upper conveyor belt rotation shaft, 42 - water remover, 5 - microwave feed, 6 - microwave source.

[0054] Some terms in this specification are defined as follows:

[0055] Horizontal plane, any plane parallel to the XZ plane.

[0056] Above, Y direction, that is, the direction perpendicular to the horizontal plane upward.

[0057] Below, -Y direction, that is, the direction perpendicular to the horizontal plane downward.

[0058] Left, X direction.

[0059] Right, -X direction.

[0060] Operating wavelength, the wavelength in air corresponding to the center operating frequency of the microwave source of the microwave device.

[0061] Microwave feed, any interface between a transmission line and a certain metal plate.

[0062] Maximum lateral dimension of a mesh, a plane curve is formed by the intersection of a plane perpendicular to the center line of a mesh and the inner wall of the mesh. The maximum distance between any two points on the plane curve is defined as the maximum lateral dimension of the mesh corresponding to the plane. The maximum lateral dimensions of the mesh corresponding to different planes perpendicular to the center line of the mesh can be different. The maximum lateral dimension of the mesh is defined as the maximum value of the maximum lateral dimensions of the mesh corresponding to different planes perpendicular to the center line of the mesh. DETAILED DESCRIPTION

[0063] Example 1

[0064] like Figure 1 As shown:

[0065] A dual-conveyor-belt tunnel furnace includes a processing chamber 1, a lower conveyor belt 3 located above the upper surface of the bottom 11 along the -Y direction of the processing chamber 1, and an upper conveyor belt 4 located below the lower surface of the top 12 along the Y direction of the processing chamber 1 and above the upper surface of the lower conveyor belt 3. A gap for accommodating the material 2 to be processed is provided between the upper conveyor belt 4 and the lower conveyor belt 3. X and Z directions are also provided, forming a rectangular coordinate system. The upper conveyor belt 4 is a mesh structure belt with several permeable water vapor and water droplet-blocking mesh holes. As shown in the figure, vertically attached... Figure 1 The orientation of the paper is the X direction.

[0066] The water-permeable and water-drop-blocking mesh is either a type A mesh or a type A1 mesh that is permeable to water vapor and a type A2 mesh that blocks water droplets.

[0067] The maximum lateral dimension of the A-type, A1-type, and A2-type meshes is less than or equal to 5 mm.

[0068] The maximum lateral dimension of the A-type, A1-type, and A2-type meshes is 1 mm, 2 mm, 3 mm, or 4 mm.

[0069] The maximum lateral dimension of A1 type mesh is greater than that of A2 type mesh.

[0070] The A1 and A2 mesh sizes are set alternately.

[0071] It also includes at least one located on the bottom 11 (such as Figure 1 (as shown) or / and located on the top 12 (as shown) Figure 3 The microwave feed port 5 (shown) and at least one microwave source 6 connected to the microwave feed port 5.

[0072] The upper conveyor belt 4 surrounds the top 12 and forms a loop, or the upper conveyor belt 4 forms a loop and is stacked in the processing cavity 1. The lowest surface of the upper conveyor belt 4 in the interior portion of the processing cavity 1 moves in the same direction as the highest surface of the lower conveyor belt 3 in the interior portion of the processing cavity 1.

[0073] At least one water separator 42 is provided outside the processing chamber 1 at a distance of less than 100 mm from the inner or outer surface of the annular upper conveyor belt 4.

[0074] At least one water separator 42 is provided at a distance of less than 10 mm from the inner or outer surface of the annular upper conveyor belt 4 outside the processing chamber 1.

[0075] To prevent the upper conveyor belt from being damaged by staying in the processing chamber for too long, we make the upper conveyor belt above the processed material move in the same direction as the lower conveyor belt below the processed material. Preferably, the upper conveyor belt above the processed material moves at a speed similar to or the same as the lower conveyor belt below the processed material. Specifically, the upper conveyor belt and the lower conveyor belt move in the same direction, and the processed material is clamped and moved by the upper conveyor belt and the lower conveyor belt.

[0076] To move the upper conveyor belt and the lower conveyor belt, the two conveyor belts are usually arranged in a ring shape with the ends connected. Both conveyor belts are partially located in the processing chamber. Each conveyor belt surrounds at least two rotating shafts. In a more common case, each conveyor belt surrounds at least four rotating shafts. Part of the surface of each conveyor belt is in contact with part of the cylindrical surface of the rotating shafts surrounded in the ring-shaped conveyor belt.

[0077] The device can be a microwave tunnel furnace: the device includes at least one microwave feed port on the top, and a microwave source connected to the at least one microwave feed port. Preferably, there is a microwave source connected to each microwave feed port. The microwave feed ports can be arranged on the top or bottom of the processing chamber, or part of them on the top and the other part on the bottom. The microwave source radiates microwave energy into the processing chamber through the microwave feed ports. Of course, the device can also be any other type of tunnel furnace.

[0078] When the device is in operation, the processed material enters the gap between the upper conveyor belt and the lower conveyor belt. The lower conveyor belt drives the processed material to move in the Z direction or in the -Z direction. Here, the processing chamber is generally a two-end-open tunnel structure with one top, one bottom, and two sides.

[0079] In a microwave tunnel furnace, we call the processing chamber fed from the top a top-fed processing chamber, and the processing chamber fed from the bottom a bottom-fed processing chamber. For ease of expression, we construct a coordinate system with a point in the processing chamber as the origin, and the bottom is generally in the -Y direction and the top is generally in the Y direction. We set the direction of the lower conveyor belt movement as the Z direction, and the direction perpendicular to the YZ plane as the X direction.

[0080] The design concept of the present technical solution is to add an upper conveyor belt above the existing lower conveyor belt in the processing cavity to isolate the processed material from the lower surface of the top of the processing cavity. In general, the upper conveyor belt can be designed as a loop like the lower conveyor belt. Specifically, the upper conveyor belt moves in the Z direction in the processing cavity. A loading body can be provided on the top of the processing cavity. The upper conveyor belt can prevent the processed material from being lifted and colliding with or rubbing against the inner surface of the top of the processing cavity in the Y direction or the loading body on the inner surface, thereby affecting the smooth passage of the processed material through the processing cavity. At the same time, the upper conveyor belt can carry out the water vapor generated in the processing cavity out of the processing cavity, preventing water droplets from forming on the bottom surface of the top of the processing cavity and falling onto the processed material. Thirdly, in the microwave tunnel furnace, the upper conveyor belt can also improve the uniformity of the processed material.

[0081] To improve the energy efficiency of the equipment, it is beneficial to use thicker processed material. A new type of microwave tunnel furnace uses a relatively short processing cavity. However, a shorter processing cavity leads to a conflict or friction between the thicker processed material and the upper inner surface of the processing cavity or the loading body located on the upper inner surface of the processing cavity. The provision of the upper conveyor belt can well solve this problem.

[0082] The upper conveyor belt can efficiently carry the water vapor generated by the processed material in the processing cavity out of the processing cavity and be eliminated by the water eliminator: blown away, sucked away, brushed away, or guided away. Otherwise, the water vapor will condense on the lower surface of the top of the processing cavity and fall onto the processed material.

[0083] To maximize the thickness of the processed material, the upper conveyor belt can be made to move in the processing cavity together with the processed material and the lower conveyor belt. Preferably, the upper conveyor belt is made to move synchronously with the processed material and the lower conveyor belt in the processing cavity.

[0084] To facilitate the elimination of water vapor generated in the processing cavity, the material of the upper conveyor belt is made of a mesh medium material, such as gauze, polyethylene mesh, etc. In special cases, the upper conveyor belt can also be made of metal wires.

[0085] In general, the mesh size of the mesh upper conveyor belt should be as large as possible to facilitate the emission of steam generated by heating, but also small enough to prevent the heated material from passing through the upper conveyor belt.

[0086] The outer shape of the upper conveyor belt is generally a loop-shaped belt. The wide side of the belt-shaped upper conveyor belt is along the X direction. The width of the belt-shaped upper conveyor belt is equal to or less than the internal width of the processing cavity.

[0087] In operation, the lower conveyor belt encircles the bottom of the processing chamber and forms a loop. Generally, the lower conveyor belt is annular and passes around at least two rollers outside the processing chamber, at least one of which is a driving roller driven by an external power source.

[0088] The lower conveyor belt can also be annular but overlaps inside the processing chamber. The two layers of the lower conveyor belt in the processing chamber move in opposite directions. The upper layer of the lower conveyor belt drives the processed material in the Z direction.

[0089] The upper conveyor belt can also be annular but overlaps inside the processing chamber. The lower layer of the upper conveyor belt, together with the upper layer of the lower conveyor belt, drives the processed material in the Z direction.

[0090] Generally, the lower conveyor belt forming a loop is a dielectric material. In special cases, the lower conveyor belt can also be formed of metal wires.

[0091] For a microwave tunnel furnace, the microwave feed ports are provided on the bottom of the processing chamber. They can also be provided on the top of the processing chamber as needed. The internal height of the processing chamber is less than the wavelength of the microwave. Preferably, the internal height of the processing chamber is less than half the wavelength of the microwave.

[0092] To remove the water vapor carried by the upper conveyor belt, at least one water vapor remover is provided at a distance from the inner or outer surface of the annular upper conveyor belt outside the processing chamber. The water vapor remover is any structure or device that can remove water vapor from the upper conveyor belt. For example, the water vapor remover can be an axial flow fan that blows air from inside or outside the annular upper conveyor belt to dry the water vapor on the upper conveyor belt. The water vapor remover can also be a dryer that bakes the upper conveyor belt at high temperature to dry the water vapor. The water vapor remover can also be a hygroscopic material such as a sponge. The water vapor remover can also be a roller brush that brushes off the water vapor on the upper conveyor belt and directs the water vapor out of the device through a flow guide structure.

[0093] The water vapor remover should be as close to the upper conveyor belt as possible without interfering with the movement of the upper conveyor belt and minimizing the friction on the upper conveyor belt. For example, at least one water vapor remover is provided at a distance of less than 100 mm from the inner or outer surface of the annular upper conveyor belt outside the processing chamber. Alternatively, at least one water vapor remover is provided at a distance of less than 10 mm from the inner or outer surface of the annular upper conveyor belt outside the processing chamber.

[0094] To facilitate the use of an air extractor to extract the water vapor generated in the processing chamber outside the processing chamber, the material of the upper conveyor belt is a mesh dielectric material.

[0095] The selection of the mesh on the upper conveyor belt is critical. The use of a mesh conveyor belt is beneficial for the evacuation of water vapor in the treatment chamber, but can cause the treated material to pass through the upper conveyor belt. We tend to use a mesh with small holes as much as possible, provided that the evacuation of water vapor in the treatment chamber is ensured. Thus, at least 50% of the mesh on the upper conveyor belt has a maximum transverse dimension of less than 10 mm, or less than 3 mm, or less than 1 mm, or less than 0.1 mm.

[0096] It should be particularly noted that:

[0097] The core technical problems to be solved by the present application have two aspects:

[0098] First: Since the treated material will be raised after heating, in order to prevent the raised treated material from colliding or rubbing with the metal load inside the treatment chamber, the present application conceives a double conveyor belt, as shown in Figure 1 、 Figure 2 、 Figure 3 , which allows the upper conveyor belt and the lower conveyor belt to pass through the treatment chamber, and the gap between them is only large enough to accommodate the thickness of the treated material. The upper conveyor belt and the lower conveyor belt move in the same direction, so that the treated material is clamped and moves in the same direction with the conveyor belt.

[0099] Second: Since the treated material will overflow water vapor after heating. The overflow water vapor will pass through the upper conveyor belt. Since microwave heating is the heating of the treated material itself, the temperature inside the treatment chamber is relatively low. The overflow water vapor will condense into water droplets at the top of the treatment chamber, which will fall onto the treated material. In order to avoid the condensation of water droplets falling back onto the treated material, the upper conveyor belt of the present application is improved by setting a mesh on the upper conveyor belt, which has the function of allowing water vapor to pass through and blocking water droplets from falling down. The mesh has the function of allowing water vapor to pass through and blocking water droplets from falling down.

[0100] In order to set a mesh with the function of allowing water vapor to pass through and blocking water droplets from falling down, the present application provides two ways to achieve it:

[0101] Method one: as shown in Figure 4 , the mesh of the upper conveyor belt is only one type of mesh, i.e. A type mesh. The size of the A type mesh is set to the purpose of preventing water droplets from passing through the upper conveyor belt. Since water droplets have tension, when the size of the A type mesh is small enough, it can prevent water droplets from passing through. Since there is only A type mesh, the mesh serves as a water vapor passing mesh and a water droplet blocking mesh, a mesh with two functions.

[0102] Method two: as shown in Figures 5 to 7As shown, the mesh of the upper conveyor belt includes two categories of mesh, namely A1 mesh and A2 mesh, namely A1 mesh for water vapor and A2 mesh for water droplets. The two meshes are independent of each other, and the size of the A1 mesh is larger than that of the A2 mesh. Compared with the first mode, the water vapor transmission efficiency is increased. Since water droplet falling is a random event, although there is a probability of passing through the A1 mesh to fall on the treated material, the probability is very small in this mode. For example, as shown in Figure 5 As shown, 1 A1 mesh for water vapor is in the center, and A2 mesh for water droplets is arranged in four directions, that is, two kinds of mesh are arranged in a dot arrangement. Figure 6 Figure 7 As shown, A1 mesh for water vapor is arranged on both sides of the running direction of the conveyor belt, and A2 mesh for water droplets is arranged in the middle of the A1 mesh for water vapor, that is, two kinds of mesh are arranged in a row arrangement. Figure 7 As shown, since the top of the processor 1 can be provided with some loading body, preferably, the A2 mesh is arranged in the central area, and the A1 mesh is arranged on both sides of the A2 mesh. In this way, the condensed water droplets will condense at the loading body in the central area of the top, and therefore, fall in the central area and be blocked by the A2 mesh. At the same time, the A2 mesh can be infinitely small or zero. Preferably, in order to increase the water vapor transmission effect, the A2 mesh can be set to a size greater than zero, but should be limited to blocking water droplets from falling. Generally, it is 1 mm or 2 mm. In addition, preferably, in order to improve the effect of blocking water droplets, the A2 mesh can be arranged as a plum blossom hole or a cross rib in the hole. In order to improve the water vapor transmission effect, the A1 mesh is arranged as a circular hole.

[0103] In use, the treated material enters the gap between the upper conveyor belt and the lower conveyor belt. The lower conveyor belt drives the treated material to move in the Z direction or in the -Z direction.

[0104] We let the upper conveyor belt move in the treatment cavity together with the treated material and the lower conveyor belt. The upper conveyor belt surrounds the top of the treatment cavity and forms a loop. The upper conveyor belt passes around 4 shafts outside the treatment cavity, one of which is a driving shaft driven by external power.

[0105] The material of the upper conveyor belt is a mesh polyethylene material. The wide side of the conveyor belt is along the X direction. The width of the annular upper conveyor belt is equal to or less than the internal width of the treatment cavity.

[0106] The internal height of the treatment cavity is less than half of the wavelength of the microwave.

[0107] ​Two water extractors 42 are arranged outside the processing chamber 1 at a distance of less than 10 mm from the outer surface of the annular upper conveyor belt 4. The water extractors are axial flow fans which extract the water vapor from the upper conveyor belt 4.

[0108] At least 50% of the holes in the upper conveyor belt 4 have a maximum lateral dimension of less than 3 mm.

[0109] The above description is only the preferred embodiments of the present application and does not limit the present application in any form. The main innovation of the present application is that the upper conveyor belt is arranged above the material to be processed, which prevents the material from being lifted and improves the energy efficiency of the equipment by removing the water vapor in the processing chamber with the upper conveyor belt. For a microwave tunnel furnace, the present application also improves the uniformity of the material processing. Any simple modification, equivalent replacement and improvement of the above embodiments within the spirit and principles of the present application are still within the protection scope of the present application. For example, the lower conveyor belt of the equipment is horizontally arranged. However, in actual applications, the entire equipment can be arranged in an inclined manner.

Claims

1. A double conveyor tunnel furnace comprising a treatment chamber (1), a lower conveyor (3) located above the upper surface of the bottom (11) of the treatment chamber (1) in the -Y direction, an upper conveyor (4) located below the lower surface of the top (12) of the treatment chamber (1) in the Y direction and above the upper surface of the lower conveyor (3), a gap being defined between the upper conveyor (4) and the lower conveyor (3) to accommodate the material to be treated (2); an X direction and a Z direction being defined, the X, Y and Z directions forming an orthogonal coordinate system, characterized in that: The upper conveyor belt (4) is a mesh structure belt with a plurality of water vapor permeable and water droplet blocking mesh holes; the water vapor permeable and water droplet blocking mesh holes are A type mesh holes that serve as both water vapor permeable mesh holes and water droplet blocking mesh holes, or the water vapor permeable and water droplet blocking mesh holes are A1 type water vapor permeable mesh holes and A2 type water droplet blocking mesh holes; the maximum transverse dimension of the A type mesh holes, the A1 type mesh holes and the A2 type mesh holes is less than or equal to 5 millimeters; the maximum transverse dimension of the A1 type mesh holes is greater than the maximum transverse dimension of the A2 type mesh holes.

2. A twin conveyor tunnel oven according to claim 1, characterized in that, The maximum transverse dimension of the A type mesh holes, the A1 type mesh holes and the A2 type mesh holes is 1 millimeter or 2 millimeters or 3 millimeters or 4 millimeters.

3. A twin conveyor tunnel oven according to claim 1, characterized in that, The A1 type mesh holes and the A2 type mesh holes are arranged at intervals.

4. A twin conveyor tunnel furnace according to any one of claims 1-3, characterized in that, Further comprising at least one microwave feed port (5) located on the bottom (11) and / or on the top (12), and at least one microwave source (6) connected to the microwave feed port (5).

5. A twin conveyor tunnel furnace according to any one of claims 1-3, characterized in that, The upper conveyor belt (4) surrounds the top (12) and forms a loop, or the upper conveyor belt (4) forms a loop and is stacked in the processing cavity (1); the lowest surface of the inner portion of the upper conveyor belt (4) in the processing cavity (1) moves in the direction of movement of the highest surface of the lower conveyor belt (3) in the inner portion of the processing cavity (1).

6. A twin conveyor tunnel furnace according to any one of claims 1-3, characterized in that, At least one water trap (42) is arranged at a distance of less than 100 millimeters from the inner surface or the outer surface of the annular upper conveyor belt (4) outside the processing cavity (1).

7. A twin conveyor tunnel furnace according to any one of claims 1-3, characterized in that At least one water trap (42) is arranged at a distance of less than 10 millimeters from the inner surface or the outer surface of the annular upper conveyor belt (4) outside the processing cavity (1).

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