A circulating hot air drying device and a circulating hot air drying production line thereof

Abstract

A circulating hot air drying device and a circulating hot air drying production line, which mainly solve the technical problems of poor drying effect, high cost of using heat source equipment and low heat source energy recovery capacity of existing drying equipment. The technical scheme points are: the circulating hot air drying device comprises a hot air device, a circulating device and a drying device, the hot air device is connected with the drying device through the circulating device and transports hot air into the drying device, the circulating device comprises a main pipe, a branch pipe and a circulating pipe, the main pipe is connected with the hot air device, one end of the branch pipe is connected with the main pipe, and the other end of the branch pipe is connected with the drying device; one end of the circulating pipe is connected with the drying device, and the other end of the circulating pipe is connected with the branch pipe. It is mainly applied to the drying of materials.

Description

Technical Field

[0001] This invention relates to a circulating hot air drying device, and more particularly to a circulating hot air drying device and its circulating hot air drying production line. Background Technology

[0002] Currently, the traditional drying air supply method involves a blower conveying hot air heated by a hot air furnace into the production line. The material is heated, the moisture evaporates, and the air is collected in the exhaust pipe after passing through the exhaust port before being discharged outdoors. This method has low energy utilization, poor drying effect of the drying equipment, and increases costs due to the use of more heat source equipment. At the same time, a large amount of usable heat is directly discharged outdoors along with the moisture.

[0003] Based on existing production lines or systems, this invention improves the hot air circulation method by circulating heat energy multiple times in the drying equipment, using the same batch of heat energy for multiple drying cycles, thereby making the drying equipment more efficient and saving energy. Summary of the Invention

[0004] The purpose of this invention is to provide a circulating hot air drying device and its circulating hot air drying production line that has high energy utilization, energy saving, low cost and convenient operation.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a circulating hot air drying device, the circulating hot air drying device including a hot air device, a circulation device and a drying device, wherein the hot air device is connected to the drying device through the circulation device and delivers hot air into the drying device; The hot air device of the present invention includes a hot air inlet and a hot air outlet. A preheating pipe is connected to the hot air inlet to preheat the air entering the hot air device. The circulation device of the present invention includes a main pipe, a branch pipe, and a circulation pipe. The main pipe is connected to the hot air outlet of the hot air device. One end of the branch pipe is connected to the main pipe, and the other end of the branch pipe is connected to the drying device. One end of the circulation pipe is connected to the drying device. The drying device of the present invention includes a drying inlet, a drying outlet, a drying air inlet, and a drying air outlet. The drying inlet is located at one end of the drying device, and the drying outlet is located at the other end of the drying device. The one end and the other end of the drying device can be the front and rear ends of the drying device, or the upper and lower ends of the same side of the drying device. The drying air inlet is located at the bottom and / or side of the drying device, preferably at the middle of the bottom of the drying device. The drying air outlet is located at the top of the drying device, preferably at the middle of the top of the drying device. The drying air inlet of the present invention includes a first drying air inlet, a second drying air inlet to an nth drying air inlet, and the first drying air inlet to the nth drying air inlet are uniformly arranged along the direction from the drying outlet to the drying inlet to ensure that the area radiated by the hot air entering the drying device from the drying air inlet is the same. The first drying air inlet of the present invention includes a first drying air inlet and a second drying air inlet. Optionally, the first drying air inlet and the second drying air inlet are respectively disposed at the bottom of the drying device; or, the first drying air inlet is disposed at the bottom of the drying device and the second drying air inlet is disposed at the side of the drying device. The first drying air inlet of the present invention includes a first drying air inlet, a second drying air inlet, and a third drying air inlet. Optionally, the first drying air inlet, the second drying air inlet, and the third drying air inlet are respectively located at the bottom of the drying device; alternatively, the first drying air inlet and the second drying air inlet are respectively located at the bottom of the drying device, and the third drying air inlet is located on the side of the drying device; alternatively, the first drying air inlet is located at the bottom of the drying device, and the second drying air inlet and the third drying air inlet are respectively located on the side of the drying device. The second drying air inlet of the present invention includes a second drying air inlet one and a second drying air inlet two. Optionally, the second drying air inlet one and the second drying air inlet two are respectively disposed at the bottom of the drying device; or, the second drying air inlet one is disposed at the bottom of the drying device and the second drying air inlet two is disposed at the side of the drying device. The second drying air inlet of the present invention includes a second drying air inlet one, a second drying air inlet two, and a second drying air inlet three. Optionally, the second drying air inlet one, the second drying air inlet two, and the second drying air inlet three are respectively located at the bottom of the drying device; alternatively, the second drying air inlet one and the second drying air inlet two are respectively located at the bottom of the drying device, and the second drying air inlet three is located on the side of the drying device; alternatively, the second drying air inlet one is located at the bottom of the drying device, and the second drying air inlet two and the second drying air inlet three are respectively located on the side of the drying device. The drying air outlet of the present invention includes a first drying air outlet, a second drying air outlet to an nth drying air outlet, and the first drying air outlet, the second drying air outlet to the nth drying air outlet are uniformly arranged along the direction from the drying outlet to the drying inlet, corresponding to the first drying air inlet to the nth drying air inlet; The circulation device of the present invention includes a first drying branch pipe, a second drying branch pipe to an nth drying branch pipe, wherein the first drying branch pipe, the second drying branch pipe to an nth drying branch pipe are correspondingly connected to the first drying air inlet, the second drying air inlet to an nth drying air inlet of the drying device; The circulation pipe of the circulation device of the present invention includes a first circulation pipe, a second circulation pipe to an nth circulation pipe. One end of the first circulation pipe, the second circulation pipe to the nth circulation pipe is connected to the first drying air outlet, the second drying air outlet to the nth drying air outlet of the drying device. The other end of the first circulation pipe to the (n-1)th circulation pipe is connected to the second drying branch pipe to the nth drying branch pipe of the branch pipe. The nth circulation pipe is fitted with a portion of the preheating pipe of the hot air device; wherein, n≥3.

[0006] The circulation device of the present invention includes a circulation fan, which includes a first circulation drying fan, a second circulation drying fan, and so on to an nth circulation drying fan. The first circulation drying fan, the second circulation drying fan, and so on to an nth circulation drying fan are arranged on the first drying branch pipe, the second drying branch pipe, and so on to an nth drying branch pipe near the drying device.

[0007] The circulation device of the present invention is also provided with a replenishment air mechanism on the branch pipe, which regulates the temperature and humidity of the drying device.

[0008] The first, second to nth drying air outlets of this invention are tapered horn-shaped openings that gradually decrease in size, making it easier for hot air to flow out of the drying equipment and into the circulation pipe.

[0009] The top of the drying device of the present invention is inclined, and the end of the top near the drying outlet is lower than the end near the drying inlet, so as to use the rising hot air to assist the hot air circulation.

[0010] The nth circulation pipe of the circulation device of the present invention is close to the air inlet of the preheating pipe and wraps a portion of the preheating pipe around the hot air device along the preheating pipe. It can utilize the residual heat of the hot air after circulation to preheat the air entering the hot air device in advance, effectively reducing the power of the hot air device, reducing energy consumption, and saving costs.

[0011] The circulating hot air drying device of the present invention further includes a secondary drying device and a secondary drying circulation device. The hot air device is connected to the secondary drying device through the secondary drying circulation device, which delivers hot air into the secondary drying device and circulates and dries the air before returning it to the circulation device. The secondary drying circulation device of the present invention includes a secondary drying branch pipe and a secondary drying circulation pipe. One end of the secondary drying branch pipe is connected to the main pipe and the other end is connected to the secondary drying device; one end of the secondary drying circulation pipe is connected to the secondary drying device. The secondary drying device of the present invention includes a secondary drying inlet, a secondary drying outlet, a secondary drying air inlet, and a secondary drying air outlet. The secondary drying inlet and the secondary drying outlet are distributed at both ends of the secondary drying device. The secondary drying air inlet is located at the bottom and / or side of the secondary drying device, and the secondary drying air outlet is located at the top of the secondary drying device. The secondary drying air inlet of the present invention includes a first secondary drying air inlet to a mth secondary drying air inlet, and the first secondary drying air inlet to the mth secondary drying air inlet are uniformly arranged along the direction from the secondary drying feed inlet to the secondary drying discharge outlet. The first secondary drying air inlet of the present invention includes a first secondary drying air inlet and a second secondary drying air inlet. Optionally, the first secondary drying air inlet and the second secondary drying air inlet are respectively located at the bottom of the drying device; or, the first secondary drying air inlet is located at the bottom of the drying device, and the second secondary drying air inlet is located on the side of the drying device. The first secondary drying air inlet of the present invention includes a first secondary drying air inlet, a second secondary drying air inlet, and a third secondary drying air inlet. Optionally, the first secondary drying air inlet, the second secondary drying air inlet, and the third secondary drying air inlet are respectively located at the bottom of the drying device; alternatively, the first secondary drying air inlet and the second secondary drying air inlet are respectively located at the bottom of the drying device, and the third secondary drying air inlet is located on the side of the drying device; alternatively, the first secondary drying air inlet is located at the bottom of the drying device, and the second and third secondary drying air inlets are respectively located on the side of the drying device. The secondary drying air outlet of the present invention includes a first secondary drying air outlet to an mth secondary drying air outlet, wherein the first secondary drying air outlet to the mth secondary drying air outlet are provided corresponding to the first secondary drying air inlet to the mth secondary drying air inlet; The secondary drying branch pipe of the secondary drying circulation device of the present invention includes a first secondary drying branch pipe to a mth secondary drying branch pipe, wherein the first secondary drying branch pipe to the mth secondary drying branch pipe are correspondingly connected to the first secondary drying air inlet to the mth secondary drying air inlet of the secondary drying device. The secondary drying circulation pipe of the present invention includes a first secondary circulation pipe to an m-th secondary circulation pipe. One end of the first secondary circulation pipe to the m-th secondary circulation pipe is connected to the first secondary drying air outlet to the m-th secondary drying air outlet. The other end of the (m-1)-th secondary circulation pipe is connected to the m-th secondary drying branch pipe. The other end of the m-th secondary circulation pipe is connected to the main pipe of the circulation device; wherein, m≥2.

[0012] The drying device and the secondary drying device of the present invention are connected by a conveying structure for transporting materials from the discharge port of the drying device to the inlet of the secondary drying device.

[0013] The drying device of this invention is externally wrapped with heat-insulating material.

[0014] The present invention discloses a circulating hot air drying production line, comprising the aforementioned circulating hot air drying device, a feeding mechanism connected to the circulating hot air drying device, a discharging mechanism connected to the circulating hot air drying device, a conveying mechanism, and a control system that simultaneously controls the circulating hot air drying device, the feeding mechanism, the discharging mechanism, and the conveying mechanism. Multiple induction controllers are respectively installed on the hot air device, the circulating device, and the drying device within the circulating hot air drying device. The control system receives signals from the induction controllers to monitor and control the start / stop and adjust the power of the hot air device, the circulating device, and the drying device in real time. It also monitors and detects the airflow and temperature of the hot air device, the circulation status and dry / wet load of the circulating device, and the drying temperature of the drying device in real time, and coordinates and regulates the hot air device, the circulating device, the drying device, the feeding mechanism, the discharging mechanism, and the conveying mechanism.

[0015] The principle of this invention is that the hot air from the hot air device is delivered to the drying device. The hot air output from the branch pipe is dried inside the drying device and then rises and is collected by the top circulation pipe and reintroduced into the branch pipe for multiple drying cycles. After multiple drying cycles, the hot air leaves the drying device.

[0016] The beneficial effects of this invention are: by using a multi-fan, multi-outlet hot air circulation method, the circulating air volume is increased, the heat source load is reduced, and the overall energy saving and emission reduction of drying are achieved while ensuring high drying efficiency. By circulating the heat energy multiple times during the drying process, the heat energy utilization rate is increased. The same batch of heat energy is used for multiple drying processes, which greatly reduces energy waste and production costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the device relationship of the present invention; Figure 2 This is a schematic diagram of the circulating hot air drying structure of the present invention; Figure 3 This is a schematic diagram of the structure of the present invention with the addition of a circulating fan; Figure 4 This is a schematic diagram showing the relationship between the secondary circulating hot air drying device added in this invention; Figure 5 This is a schematic diagram of the structure of the additional secondary circulating hot air drying device in this invention; Figure 6 This is a schematic diagram illustrating the principle of the circulating hot air drying of the present invention; Figure 7 These are two schematic diagrams illustrating the principle of the circulating hot air drying of this invention; In the diagram: 1-Hot air device, 2-Circulation device, 3-Drying device, 21-Main pipe, 22-Branch pipe, 23-Circulation pipe, 11-Hot air inlet, 12-Hot air outlet, 13-Preheating pipe, 31-Drying feed inlet, 32-Drying discharge outlet, 33-Drying air inlet, 34-Drying air outlet, 331-First drying air inlet, 332-Second drying air inlet, 333-Third drying air inlet, 341-First drying air outlet, 342-Second drying air outlet, 343-Third drying air outlet, 221-First drying branch pipe, 222-Second drying branch pipe, 223-Third drying branch pipe, 231-First circulation pipe, 232-Second circulation pipe, 233-Third circulation pipe Pipe, 241-First circulating drying fan, 242-Second circulating drying fan, 243-Third circulating drying fan, 4-Secondary drying device, 5-Secondary drying circulation device, 6-Conveying structure, 51-Secondary drying branch pipe, 52-Secondary drying circulation pipe, 41-Secondary drying inlet, 42-Secondary drying outlet, 43-Secondary drying air inlet, 44-Secondary drying air outlet, 431-First secondary drying air inlet, 432-Secondary drying air inlet, 441-First secondary drying air outlet, 442-Secondary drying air outlet, 511-First secondary drying branch pipe, 512-Secondary drying branch pipe, 521-First secondary circulation pipe, 522-Secondary circulation pipe. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is not intended to limit this application or its application or use in any way. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0022] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0023] Furthermore, it should be noted that the use of terms such as "the first" and "the second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0024] Example 1, see Figure 1 The circulating hot air drying device of the present invention includes a hot air device 1, a circulation device 2, and a drying device 3. The hot air device 1 is connected to the drying device 3 through the circulation device 2 and delivers hot air into the drying device 3. The circulation device 2 includes a main pipe 21, a branch pipe 22, and a circulation pipe 23. The main pipe 21 is connected to the hot air device 1. One end of the branch pipe 22 is connected to the main pipe 21, and the other end of the branch pipe 22 is connected to the drying device 3. One end of the circulation pipe 23 is connected to the drying device 3, and the other end is connected to the branch pipe 22.

[0025] Example 2, see Figure 2 The hot air device 1 of the present invention includes a hot air inlet 11 and a hot air outlet 12, and a preheating pipe 13 is connected to the hot air inlet 12. The circulation device 2 of the present invention includes a main pipe 21, a branch pipe 22 and a circulation pipe 23. The main pipe 21 is connected to the hot air outlet 12 of the hot air device 1. One end of the branch pipe 22 is connected to the main pipe 21 and the other end of the branch pipe 22 is connected to the drying device 3. One end of the circulation pipe 23 is connected to the drying device 3. The drying device 3 of the present invention includes a drying inlet 31, a drying outlet 32, a drying air inlet 33 and a drying air outlet 34. The drying air inlet 31 is disposed at the bottom and / or side of the drying device 3, and the drying air outlet 33 is disposed at the top of the drying device 3. The drying air inlet 33 of the present invention includes a first drying air inlet 331, a second drying air inlet 332 and a third drying air inlet 333, wherein the first drying air inlet 331, the second drying air inlet 332 and the third drying air inlet 333 are uniformly arranged along the direction from the drying outlet 32 ​​to the drying inlet 31. The drying air outlet 34 of the present invention includes a first drying air outlet 341, a second drying air outlet 342, and a third drying air outlet 343. The first drying air outlet 341, the second drying air outlet 342, and the third drying air outlet 343 are uniformly arranged along the direction from the drying outlet 32 ​​to the drying inlet 31, corresponding to the first drying inlet 331, the second drying inlet 332, and the third drying inlet 333. The circulation device of the present invention includes a first drying branch pipe 221, a second drying branch pipe 222 and a third drying branch pipe 223, wherein the first drying branch pipe 221, the second drying branch pipe 222 and the third drying branch pipe 223 are respectively connected to the first drying air inlet 331, the second drying air inlet 332 and the third drying air inlet 333 of the drying device; The circulation pipe 23 of the circulation device of the present invention includes a first circulation pipe 231, a second circulation pipe 232 and a third circulation pipe 233. One end of the first circulation pipe 231, the second circulation pipe 232 and the third circulation pipe 233 are respectively connected to the first drying air outlet 341, the second drying air outlet 342 and the third drying air outlet 343. The other end of the first circulation pipe 231 and the second circulation pipe 232 are respectively connected to the second drying branch pipe 222 and the third drying branch pipe 223 of the branch pipe. The third circulation pipe 233 is fitted with part of the preheating pipe 13 of the hot air device.

[0026] Example 3, see Figure 3 The circulation device 2 of the present invention includes a circulation fan, which includes a first circulation drying fan 241, a second circulation drying fan 242, and a third circulation drying fan 243. The first circulation drying fan 241, the second circulation drying fan 242, and the third circulation drying fan 243 are arranged on the first drying branch pipe 221, the second drying branch pipe 222, and the third drying branch pipe 223 near the drying device 3; the rest is the same as any other embodiment of the present invention or a combination of two or more embodiments.

[0027] Example 4, see Figure 4The circulating hot air drying device of the present invention includes a hot air device 1, a circulation device 2, a drying device 3, a secondary drying device 4, and a secondary drying circulation device 5. The hot air device 1 is connected to the secondary drying device 4 through the secondary drying circulation device 5, which delivers hot air into the secondary drying device 4 and circulates and dries the air before returning it to the circulation device 2. A conveying structure 6 is provided between the drying device 3 and the secondary drying device 4. The rest is the same as any other embodiment of the present invention or a combination of two or more embodiments.

[0028] Example 5, see Figure 5 The secondary drying circulation device 5 of the present invention includes a secondary drying branch pipe 51 and a secondary drying circulation pipe 52. One end of the secondary drying branch pipe 51 is connected to the main pipe 21 and the other end is connected to the secondary drying device 4; one end of the secondary drying circulation pipe 52 is connected to the secondary drying device 4. The secondary drying device 4 of the present invention includes a secondary drying inlet 41, a secondary drying outlet 42, a secondary drying air inlet 43, and a secondary drying air outlet 44. The secondary drying inlet 41 and the secondary drying outlet 42 are distributed at both ends of the secondary drying device, the secondary drying air inlet 43 is located at the bottom and / or side of the secondary drying device, and the secondary drying air outlet 44 is located at the top of the secondary drying device. The secondary drying air inlet 43 of the present invention includes a first secondary drying air inlet 431 and a second secondary drying air inlet 432, wherein the first secondary drying air inlet 431 and the second secondary drying air inlet 432 are uniformly arranged along the direction from the secondary drying feed inlet 41 to the secondary drying discharge outlet 42. The secondary drying air outlet 44 of the present invention includes a first secondary drying air outlet 441 and a second secondary drying air outlet 442, wherein the first secondary drying air outlet 441 and the second secondary drying air outlet 442 are provided corresponding to the first secondary drying air inlet 431 and the second secondary drying air inlet 432. The secondary drying branch pipe 51 of the present invention includes a first secondary drying branch pipe 511 and a second secondary drying branch pipe 512, wherein the first secondary drying branch pipe 511 and the second secondary drying branch pipe 512 are respectively connected to the first secondary drying air inlet 431 and the second secondary drying air inlet 432. The secondary drying circulation pipe 52 of the present invention includes a first secondary circulation pipe 521 and a second secondary circulation pipe 522. One end of the first secondary circulation pipe 521 and the second secondary circulation pipe 522 corresponds to the first secondary drying air outlet 441 and the second secondary drying air outlet 442, respectively. The other end of the first secondary circulation pipe 521 is connected to the second secondary drying branch pipe 512, and the other end of the second secondary circulation pipe 522 is connected to the main pipe 21 of the circulation device. The rest is the same as any other embodiment of the present invention or a combination of two or more embodiments.

Claims

1. A circulating hot air drying device, characterized in that: The circulating hot air drying device includes a hot air device, a circulation device, and a drying device. The hot air device is connected to the drying device through the circulation device and delivers hot air into the drying device. The hot air device includes a hot air inlet and a hot air outlet, and a preheating pipe is connected to the hot air inlet. The circulation device includes a main pipe, branch pipes, and a circulation pipe. The main pipe is connected to the hot air outlet of the hot air device. One end of the branch pipe is connected to the main pipe, and the other end of the branch pipe is connected to the drying device. One end of the circulation pipe is connected to the drying device. The drying device includes a drying inlet, a drying outlet, a drying air inlet, and a drying air outlet. The drying inlet is located at one end of the drying device, the drying outlet is located at the other end of the drying device, the drying air inlet is located at the bottom and / or side of the drying device, and the drying air outlet is located at the top of the drying device. The drying air inlet includes a first drying air inlet, a second drying air inlet, and so on up to an nth drying air inlet. The first drying air inlet and the nth drying air inlet are evenly arranged along the direction from the drying outlet to the drying inlet. The drying air outlet includes a first drying air outlet, a second drying air outlet to an nth drying air outlet, and the first drying air outlet, the second drying air outlet to an nth drying air outlet are uniformly arranged along the direction from the drying outlet to the drying inlet, corresponding to the first drying air inlet to the nth drying air inlet; The circulation device includes a first drying branch pipe, a second drying branch pipe, and so on up to the nth drying branch pipe. The first drying branch pipe, the second drying branch pipe, and so on up to the nth drying branch pipe are respectively connected to the first drying air inlet, the second drying air inlet, and so on up to the nth drying air inlet of the drying device. The circulation pipe of the circulation device includes a first circulation pipe, a second circulation pipe to an nth circulation pipe. One end of the first circulation pipe, the second circulation pipe to the nth circulation pipe is connected to the first drying air outlet, the second drying air outlet to the nth drying air outlet of the drying device. The other end of the first circulation pipe to the (n-1)th circulation pipe is connected to the second drying branch pipe to the nth drying branch pipe of the branch pipe. The nth circulation pipe is fitted with part of the preheating pipe of the hot air device; wherein, n≥3.

2. The circulating hot air drying device according to claim 1, characterized in that: The circulation device includes a circulation fan, which includes a first circulation drying fan, a second circulation drying fan, and so on up to an nth circulation drying fan. The first circulation drying fan, the second circulation drying fan, and so on up to an nth circulation drying fan are installed on the first drying branch pipe, the second drying branch pipe, and so on up to an nth drying branch pipe, which are close to the drying device.

3. The circulating hot air drying device according to claim 1, characterized in that: The circulation device is also equipped with a make-up air mechanism on its branch pipe, which regulates the temperature and humidity of the drying device.

4. The circulating hot air drying device according to claim 1, characterized in that: The first, second, and nth drying air outlets are successively smaller conical horn-shaped openings.

5. The circulating hot air drying device according to claim 1, characterized in that: The top of the drying device is inclined, with the end of the top near the drying outlet lower than the end near the drying inlet.

6. The circulating hot air drying device according to claim 1, characterized in that: The nth circulation pipe of the circulation device is close to the air inlet of the preheating pipe and wraps around a portion of the preheating pipe towards the hot air device.

7. The circulating hot air drying device according to claim 1, characterized in that: The circulating hot air drying device also includes a secondary drying device and a secondary drying circulation device. The hot air device is connected to the secondary drying device through the secondary drying circulation device, which delivers hot air into the secondary drying device and circulates and dries the air before returning it to the circulation device. The secondary drying circulation device includes a secondary drying branch pipe and a secondary drying circulation pipe. One end of the secondary drying branch pipe is connected to the main pipe, and the other end is connected to the secondary drying device. One end of the secondary drying circulation pipe is connected to the secondary drying device; The secondary drying device includes a secondary drying inlet, a secondary drying outlet, a secondary drying air inlet, and a secondary drying air outlet. The secondary drying inlet and the secondary drying outlet are distributed at both ends of the secondary drying device. The secondary drying air inlet is located at the bottom and / or side of the secondary drying device, and the secondary drying air outlet is located at the top of the secondary drying device. The secondary drying air inlet includes a first secondary drying air inlet to a mth secondary drying air inlet, and the first secondary drying air inlet to the mth secondary drying air inlet are uniformly arranged along the direction from the secondary drying feed inlet to the secondary drying discharge outlet. The secondary drying air outlet includes a first secondary drying air outlet to a mth secondary drying air outlet, and the first secondary drying air outlet to the mth secondary drying air outlet are set to correspond to the first secondary drying air inlet to the mth secondary drying air inlet. The secondary drying circulation device includes a first secondary drying branch pipe to a mth secondary drying branch pipe, and the first secondary drying branch pipe to the mth secondary drying branch pipe are connected to the first secondary drying air inlet to the mth secondary drying air inlet of the secondary drying device. The secondary drying circulation pipe includes a first secondary circulation pipe to an m-th secondary circulation pipe. One end of the first secondary circulation pipe to the m-th secondary circulation pipe is connected to the first secondary drying air outlet to the m-th secondary drying air outlet. The other end of the (m-1)-th secondary circulation pipe is connected to the m-th secondary drying branch pipe. The other end of the m-th secondary circulation pipe is connected to the main pipe of the circulation device; wherein, m≥2.

8. The circulating hot air drying device according to claim 7, characterized in that: A conveyor structure is provided to connect the drying device and the secondary drying device.

9. The circulating hot air drying apparatus according to any one of claims 1-8, characterized in that: The drying device is wrapped with heat-insulating material.

10. A circulating hot air drying production line, characterized in that: The production line includes a circulating hot air drying device as described in any one of claims 1-8, a feeding mechanism connected to the circulating hot air drying device, a discharging mechanism connected to the circulating hot air drying device, a conveying mechanism, and a control system that simultaneously controls the circulating hot air drying device, the feeding mechanism, the discharging mechanism, and the conveying mechanism. Multiple induction controllers are respectively installed on the hot air device, the circulating device, and the drying device within the circulating hot air drying device. The control system receives signals from the induction controllers to monitor and control the start / stop power of the hot air device, the circulating device, and the drying device in real time. It also monitors and detects the air volume and temperature of the hot air device, the circulation status and dry / wet load of the circulating device, and the drying temperature of the drying device in real time, and coordinates and regulates the hot air device, the circulating device, the drying device, the feeding mechanism, the discharging mechanism, and the conveying mechanism.

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