A gas external circulation system applied to a fluidized bed type silane deposition furnace

Abstract

The present invention relates to the field of new silicon carbide deposition equipment, and particularly to a gas external circulation system applied to a fluidized bed type silane deposition furnace, which includes a support, a columnar fluidized bed, a three-way pipe, a carrier, a cooler, a pressurizer, a heater, a ventilation pipe, an exhaust pipe and an injection pipe; the support is installed with the columnar fluidized bed; the columnar fluidized bed is communicated with the three-way pipe; the support is provided with the carrier; the carrier is sequentially installed with the cooler, the pressurizer and the heater from top to bottom; the cooler, the pressurizer and the heater are jointly communicated with a ventilation pipe; the ventilation pipe and the columnar fluidized bed are jointly communicated with an exhaust pipe; the ventilation pipe and the three-way pipe are jointly communicated with an injection pipe. The present invention filters the process gas through a flexibly adjustable dust-absorbing cloth, solving the problem in the prior art that the cleaning of the dust filtration equipment can only be carried out after the silane deposition furnace equipment is cooled down, and the non-stop cleaning or replacement of the dust filtration equipment cannot be achieved.

Description

Technical Field

[0001] The present invention relates to the field of new silicon carbide deposition equipment, and in particular to a gas external circulation system applied to a fluidized bed type silane deposition furnace. Background Art

[0002] Silicon-based anodes are regarded as the most promising next-generation lithium battery anode materials, which can greatly improve the energy density of lithium batteries. At present, the penetration rate of silicon-based anode materials is gradually increasing. There are two research and development ideas for silicon-based anodes: 1) silicon-oxygen anodes, in which silicon monoxide is combined with graphite materials; 2) silicon-carbon anodes, in which nano-silicon is combined with porous carbon materials. Silicon-carbon anodes can reduce the cost of pre-lithiation or magnesiation and have the potential to significantly reduce costs compared to the silicon-oxygen route. The preparation of silicon-carbon anodes can be divided into two stages. First, a porous carbon skeleton structure is manufactured by high-temperature carbonization and activation etching of carbon-rich materials (preparation of porous carbon). Subsequently, a silicon-containing compound is transported into the pores of the porous carbon skeleton, and the gas is pyrolyzed at high temperature to deposit silicon nanoparticles (silicon deposition).

[0003] Currently, during the preparation of silicon-carbon anodes, when using a fluidized bed to deposit and coat silicon-carbon materials, a large amount of unreacted process gas will directly be discharged from the reactor. Most fluidized bed type silane deposition furnace equipment does not utilize this part of the process gas, resulting in great waste; a small part of fluidized bed type silane deposition furnace equipment will recycle this part of the process gas. During the recycling process of the process gas, generally, steps such as filtration and dust removal - cooling - pressurization - heating are experienced successively, and finally, the process gas is transported into the silane deposition furnace equipment; however, the method of filtering and dust removing first and then cooling will cause the filtering equipment to be in contact with high-temperature gas for a long time, resulting in a short service life of the filtering and dust removal equipment; moreover, when the filtering and dust removal equipment is blocked by particulate matter in the process gas after a long period of filtering and dust removal work, since the filtering and dust removal equipment is directly in contact with high-temperature gas, it is necessary to wait for the silane deposition furnace equipment to cool down before cleaning the filtering and dust removal equipment, and it is impossible to achieve non-stop cleaning or replacement of the filtering and dust removal equipment, which needs to be improved. Summary of the Invention

[0004] In order to overcome the disadvantages mentioned in the background, the present invention provides a gas external circulation system applied to a fluidized bed type silane deposition furnace.

[0005] Technical solution: A gas external circulation system applied to a fluidized bed type silane deposition furnace, comprising a bracket, a columnar fluidized bed, a three-way pipe, a carrier frame, a cooler, a pressurizer, a heater, a ventilation pipe, an exhaust pipe and an injection pipe; The bracket is installed with a columnar fluidized bed; The columnar fluidized bed is connected to a three-way pipe; The bracket is provided with a carrier frame; The carrier frame is successively installed with a cooler, a pressurizer and a heater from top to bottom; The cooler, the pressurizer and the heater are jointly connected to a ventilation pipe; The ventilation pipe and the columnar fluidized bed are jointly connected to an exhaust pipe; The ventilation pipe and the three-way pipe are jointly connected to an injection pipe; It further comprises a cylinder, a mounting frame, a roller, a driving motor, a rotating rod, a dust-absorbing cloth, a cleaner, an annular frame and a pressing roller; The ventilation pipe is divided into upper, middle and lower sections, and a mounting frame is fixedly connected between each adjacent two sections; The middle section of the ventilation pipe is arranged in a "C" shape; A cylinder is arranged inside the middle section of the ventilation pipe, and there is a gap between the cylinder and the middle section of the ventilation pipe; A plurality of symmetrically distributed rollers are rotatably connected by all the mounting frames; A plurality of driving motors are installed on the upper section of the ventilation pipe, and the driving motors correspond to the rollers one by one, and the output shafts of each driving motor are fixedly connected to the corresponding side rollers respectively; A plurality of annularly distributed rotating rods are rotatably connected by all the mounting frames; A double-layer "C" shaped dust-absorbing cloth is jointly driven by all the rollers and the rotating rods, and the double-layer "C" shaped dust-absorbing cloth covers the middle section of the ventilation pipe; Each mounting frame is fixedly connected with an annular frame; Each annular frame is rotatably connected with a plurality of annularly distributed pressing rollers, and the pressing rollers are attached to the dust-absorbing cloth; A cleaner is jointly installed on the upper section and the lower section of the ventilation pipe, and the cleaner covers the dust-absorbing cloth.

[0006] Further explanation, it further comprises an electric push rod and an arc-shaped pressing plate; A plurality of vertically arrayed electric push rods are installed on the carrier frame; The telescopic parts of all the electric push rods are jointly fixedly connected with an arc-shaped pressing plate, and the arc-shaped pressing plate is attached to the dust-absorbing cloth; The length of the arc-shaped pressing plate is greater than that of the dust-absorbing cloth, and the parts of the arc-shaped pressing plate extending beyond the dust-absorbing cloth at both ends are respectively attached to the upper section and the lower section of the ventilation pipe.

[0007] Further explanation, a number of fine hairs are arranged on the surface of the dust-absorbing cloth.

[0008] Further explanation, a number of vertically arrayed guiding convex strips are arranged on the dust-absorbing cloth, and the guiding convex strips are made of dust-absorbing material; The guiding convex strips have the ability of elastic deformation.

[0009] Further explanation, a number of frustum-shaped guiding rings are arranged on the cylinder, and the frustum-shaped guiding rings and the guiding convex strips are arranged in a staggered manner.

[0010] Further explanation, a fan is installed on the lower section of the ventilation pipe, and the rotating shaft of the fan is fixedly connected to the cylinder, and the cylinder is connected to the lower section of the ventilation pipe through the fan.

[0011] Further explanation: The cylinder is equipped with a crushing knife, and the crushing knife is close to the upper section of the ventilation pipe.

[0012] Further explanation: A flow dividing column is fixedly connected inside the upper section of the ventilation pipe, and there is a gap between the flow dividing column and the upper section of the ventilation pipe.

[0013] Further explanation: A funnel-shaped flow concentrating ring is fixedly connected inside the upper section of the ventilation pipe, and the flow concentrating ring is located below the flow dividing column and cooperates with the crushing knife.

[0014] The beneficial effects of the present invention are as follows:

[0015] 1. The present invention uses a flexible dust-absorbing cloth to filter process gas, solving the problem in the prior art that the cleaning of the dust filtering and removing equipment can only be carried out after the silane deposition furnace equipment cools down, and it is impossible to achieve non-stop cleaning or replacement of the dust filtering and removing equipment.

[0016] 2. In the present invention, the process gas flowing through the middle section of the ventilation pipe from top to bottom will first be guided by the inclined surface of the uppermost frustum-shaped guiding ring and move towards the dust-absorbing cloth. Then, it will be further guided by the guiding convex strips and move towards the inclined surface of the next frustum-shaped guiding ring. Repeating this process multiple times, under the combined action of multiple frustum-shaped guiding rings and multiple guiding convex strips, the process gas will flow in a zigzag pattern, further prolonging the contact time between the process gas and the dust-absorbing cloth, thereby further enhancing the adsorption and interception effect of the dust-absorbing cloth on the particulate matter entrained in the process gas.

[0017] 3. In the present invention, the process gas flowing through the ventilation pipe from top to bottom will drive the fan to rotate, and thus the fan will drive the cylinder and the crushing knife to rotate. The rotating crushing knife will break up the agglomerated particulate matter, preventing the particulate matter entrained in the process gas from agglomerating.

[0018] 4. The present invention uses the flow concentrating ring to concentrate the process gas and the particulate matter it entrains towards the area where the crushing knife is located, enhancing the effect of the crushing knife in breaking up the agglomerated particulate matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram disclosed by the present invention;

[0020] Figure 2 is a schematic combined structural diagram of a cooler, a pressure booster, a heater and a ventilation pipe disclosed by the present invention;

[0021] Figure 3 is a structural sectional view of a cleaner disclosed by the present invention;

[0022] Figure 4 is a structural sectional view of a ventilation pipe disclosed by the present invention;

[0023] Figure 5 Schematic diagram of the combined structure of the crushing knife, shunt column and confluence ring disclosed by the present invention;

[0024] Figure 6 Schematic diagram of the combined structure of the dust-absorbing cloth and the guiding rib disclosed by the present invention;

[0025] Figure 7 Cross-sectional view of the structure of the dust-absorbing cloth disclosed by the present invention;

[0026] Figure 8 Exploded view of the structure of the ventilation pipe and the mounting bracket disclosed by the present invention;

[0027] Figure 9 Schematic diagram of the combined structure of the ventilation pipe, cylinder and dust-absorbing cloth disclosed by the present invention;

[0028] Figure 10 Schematic diagram of the combined structure of the rotating roller, rotating rod and dust-absorbing cloth disclosed by the present invention;

[0029] Figure 11 Schematic diagram of the airflow direction disclosed by the present invention.

[0030] Reference signs in the drawings: 1 - support, 2 - columnar fluidized bed, 3 - tee pipe, 4 - carrier, 5 - cooler, 6 - pressurizer, 7 - heater, 8 - ventilation pipe, 9 - cylinder, 10 - mounting bracket, 11 - rotating roller, 111 - drive motor, 12 - rotating rod, 13 - dust-absorbing cloth, 14 - exhaust pipe, 15 - injection pipe, 16 - electric push rod, 17 - arc-shaped pressing plate, 18 - cleaner, 19 - annular frame, 191 - pressing roller, 20 - guiding rib, 21 - frustum-shaped guiding ring, 30 - fan, 31 - crushing knife, 40 - shunt column, 41 - confluence ring. Detailed implementation manners

[0031] The present invention will be further described below in conjunction with specific embodiments. The illustrative embodiments and explanations of this invention are used to explain the present invention, but do not limit the present invention.

[0032] Embodiment 1

[0033] A gas external circulation system applied to a fluidized bed type silane deposition furnace, as Figures 1-11As shown in the figure, it includes a support 1, a columnar fluidized bed 2, a three-way pipe 3, a carrier 4, a cooler 5, a pressurizer 6, a heater 7, a ventilation pipe 8, an exhaust pipe 14, and an injection pipe 15; the support 1 is installed with the columnar fluidized bed 2; the columnar fluidized bed 2 is connected to the three-way pipe 3; the support 1 is provided with the carrier 4; the carrier 4 is successively installed with the cooler 5, the pressurizer 6, and the heater 7 from top to bottom; the cooler 5, the pressurizer 6, and the heater 7 are jointly connected to a ventilation pipe 8; the ventilation pipe 8 and the columnar fluidized bed 2 are jointly connected to an exhaust pipe 14; the ventilation pipe 8 and the three-way pipe 3 are jointly connected to an injection pipe 15;

[0034] It also includes a cylinder 9, a mounting frame 10, a roller 11, a driving motor 111, a rotating rod 12, a dust-absorbing cloth 13, a cleaner 18, an annular frame 19, and a pressing roller 191; the ventilation pipe 8 is divided into upper, middle, and lower sections, and a mounting frame 10 is fixedly connected between each adjacent two sections; the middle section of the ventilation pipe 8 is arranged in a "C" shape; a cylinder 9 is arranged inside the middle section of the ventilation pipe 8, and there is a gap between the cylinder 9 and the middle section of the ventilation pipe 8; at least two symmetrically distributed rollers 11 are jointly rotatably connected by all the mounting frames 10; at least two driving motors 111 are installed on the upper section of the ventilation pipe 8, and the driving motors 111 correspond to the rollers 11 one by one, and the output shaft of each driving motor 111 is fixedly connected to the corresponding roller 11; at least six annularly distributed rotating rods 12 are jointly rotatably connected by all the mounting frames 10; a double-layer "C"-shaped dust-absorbing cloth 13 is jointly driven by all the rollers 11 and the rotating rods 12, and the double-layer "C"-shaped dust-absorbing cloth 13 covers the middle section of the ventilation pipe 8; each mounting frame 10 is fixedly connected with an annular frame 19; at least seven annularly distributed pressing rollers 191 are rotatably connected to each annular frame 19, and the pressing rollers 191 are in contact with the dust-absorbing cloth 13, and the dust-absorbing cloth 13 is limited by the pressing rollers 191 to make the dust-absorbing cloth 13 fit the inner wall of the ventilation pipe 8 to prevent the dust-absorbing cloth 13 from deforming; a cleaner 18 is installed on both the upper section and the lower section of the ventilation pipe 8, and the cleaner 18 covers the dust-absorbing cloth 13.

[0035] It also includes an electric push rod 16 and an arc-shaped pressing plate 17; at least three vertically arrayed electric push rods 16 are installed on the carrier 4; the telescopic parts of all the electric push rods 16 are jointly fixedly connected with an arc-shaped pressing plate 17, and the arc-shaped pressing plate 17 is in contact with the dust-absorbing cloth 13; the length of the arc-shaped pressing plate 17 is greater than that of the dust-absorbing cloth 13, and the parts of the arc-shaped pressing plate 17 exceeding both ends of the dust-absorbing cloth 13 are respectively in contact with the upper section and the lower section of the ventilation pipe 8; the arc-shaped pressing plate 17 presses and seals the notch of the double-layer "C"-shaped dust-absorbing cloth 13 to prevent the process gas from overflowing outward from the notch of the double-layer "C"-shaped dust-absorbing cloth 13.

[0036] Several fine hairs are arranged on the surface of the dust-absorbing cloth 13 to improve the adsorption effect of the dust-absorbing cloth 13 on the particulate matter carried in the process gas.

[0037] The specific working process of the present invention is as follows:

[0038] First, silicon-carbon materials are fed into the columnar fluidized bed 2 through the feed inlet on the columnar fluidized bed 2. Then, an external air pump is controlled to input process gas into the columnar fluidized bed 2 through the three-way pipe 3, so as to deposit and coat the silicon-carbon materials by using the columnar fluidized bed 2, thereby realizing the preparation of the silicon-carbon negative electrode. Among them, the unreacted process gas is transported from the columnar fluidized bed 2 to the ventilation pipe 8 through the exhaust pipe 14, so that the process gas passes through the ventilation pipe 8 from top to bottom, and the steps of cooling, filtering, pressurizing and heating are carried out in sequence. Then, the heated process gas is transported into the columnar fluidized bed 2 through the injection pipe 15 and the three-way pipe 3, realizing the recycling operation of the process gas.

[0039] Specifically, in the above process, when the process gas flows through the cooler 5, the cooler 5 cools the process gas to a preset temperature to avoid damaging the dust suction cloth 13 and the pressurizer 6 in the subsequent filtering and pressurizing processes. When the process gas flows through the dust suction cloth 13, the dust suction cloth 13 intercepts and adsorbs the particulate matters carried in the process gas to ensure the purity of the process gas. When the process gas flows through the pressurizer 6, the pressurizer 6 pressurizes the process gas after cooling and filtering, and pressurizes the cooled process gas to the preset reaction pressure. When the process gas flows through the heater 7, the heater 7 heats the pressurized gas to make the process gas heated to the preset reaction temperature.

[0040] Among them, after the dust-absorbing cloth 13 has undergone a long period of adsorption and filtration work, a large amount of particulate matter will adhere to its surface. Therefore, to ensure that the dust-absorbing cloth 13 always has good adsorption and filtration effects, after each preparation work of the silicon-carbon negative electrode is completed, first control the telescopic part of the electric push rod 16 to drive the arc-shaped pressing plate 17 to move towards the center point of the ventilation pipe 8, so that the arc-shaped pressing plate 17 is far away from the pipe wall of the ventilation pipe 8 and the dust-absorbing cloth 13, and thus no longer presses the dust-absorbing cloth 13, enabling the dust-absorbing cloth 13 to move under the rotation of the roller 11; then, control the output shaft of the driving motor 111 to drive the roller 11 to rotate clockwise from a top-down perspective, thereby driving the dust-absorbing cloth 13 to move along the middle section of the ventilation pipe 8 through the roller 11, and assisting the movement of the dust-absorbing cloth 13 through the rotating rod 12, so that a part of the dust-absorbing cloth 13 that was originally inside the ventilation pipe 8 and adsorbed a large amount of particulate matter gradually moves to the outside of the ventilation pipe 8, while a part of the dust-absorbing cloth 13 that was originally outside the ventilation pipe 8 and in a clean state gradually moves to the inside of the ventilation pipe 8, realizing the position exchange of the part of the dust-absorbing cloth 13 inside the ventilation pipe 8 and the part of the dust-absorbing cloth 13 outside the ventilation pipe 8. At the same time, control the cleaner 18 to clean the part of the dust-absorbing cloth 13 outside the ventilation pipe 8, and discharge the sewage through an externally connected drain pipe. In this way, the process gas is filtered by the flexibly adjustable dust-absorbing cloth 13, solving the problem in the prior art that the cleaning of the dust removal equipment can only be carried out after the silane deposition furnace equipment cools down, and the non-stop cleaning or replacement of the dust removal equipment cannot be realized.

[0041] Embodiment 2

[0042] On the basis of the above Embodiment 1, as Figures 6-11 shown, the dust-absorbing cloth 13 is provided with at least four guiding convex strips 20 distributed in a vertical array, and the guiding convex strips 20 are made of dust-absorbing material; the guiding convex strips 20 have the ability of elastic deformation, so that the pressing roller 191 can normally press them.

[0043] As Figure 9 shown, the cylinder 9 is provided with at least four frustum-shaped guiding rings 21 distributed in a vertical array, and the frustum-shaped guiding rings 21 and the guiding convex strips 20 are distributed in a staggered manner.

[0044] The specific working process of the present invention is as follows:

[0045] During the above filtering process, the guiding ridges 20 provided on the dust suction cloth 13 play a blocking role on the process gas flowing between the cylinder 9 and the dust suction cloth 13, slowing down the flow rate of the process gas to a certain extent, thereby increasing the contact time and contact area between the process gas and the dust suction cloth 13, and enhancing the adsorption and interception effects of the dust suction cloth 13 on the particulate matter entrained by the process gas. At the same time, since the frustum-shaped guiding rings 21 and the guiding ridges 20 are staggered, the process gas flowing through the middle section of the ventilation pipe 8 from top to bottom will first be guided by the inclined surface of the uppermost frustum-shaped guiding ring 21 and move towards the dust suction cloth 13. Then, it will be guided by the guiding ridges 20 and move towards the inclined surface of the next frustum-shaped guiding ring 21. This repeats multiple times. Under the combined action of multiple frustum-shaped guiding rings 21 and multiple guiding ridges 20, the process gas is repeatedly deflected, as shown in Figure 11 shown, further prolonging the contact time between the process gas and the dust suction cloth 13, thereby further enhancing the adsorption and interception effects of the dust suction cloth 13 on the particulate matter entrained by the process gas.

[0046] Embodiment 3

[0047] Based on the above Embodiment 2, as shown in Figures 7-9 shown, a fan 30 is installed at the lower section of the ventilation pipe 8, and the rotating shaft of the fan 30 is fixedly connected to the cylinder 9. The cylinder 9 is connected to the lower section of the ventilation pipe 8 through the fan 30.

[0048] As shown in Figure 5 shown, a crushing knife 31 is installed on the cylinder 9, and the crushing knife 31 is close to the upper section of the ventilation pipe 8.

[0049] As shown in Figures 4-5 shown, a flow dividing column 40 is fixedly connected inside the upper section of the ventilation pipe 8, and there is a gap between the flow dividing column 40 and the upper section of the ventilation pipe 8. The high-temperature process gas is divided by the flow dividing column 40, so that the high-temperature process gas enters the gap between the flow dividing column 40 and the upper section of the ventilation pipe 8, making the high-temperature process gas closer to the cooler 5 and enhancing the cooling effect on the high-temperature process gas.

[0050] As shown in Figures 4-5 shown, a funnel-shaped converging ring 41 is fixedly connected inside the upper section of the ventilation pipe 8, and the converging ring 41 is located below the flow dividing column 40 and cooperates with the crushing knife 31.

[0051] The specific working process of the present invention is as follows:

[0052] In the above process, the process gas flowing through the vent pipe 8 from top to bottom drives the fan 30 to rotate, so that the fan 30 drives the cylinder 9 and the frustum-shaped guide ring 21 to rotate. When the particulate matter contacts the cylinder 9 and the frustum-shaped guide ring 21, the rotating cylinder 9 and frustum-shaped guide ring 21 cause the particulate matter to be centrifugally thrown away, and the particulate matter entrained in the process gas is thrown towards the dust-absorbing cloth 13 in a dispersed state, so that the particulate matter entrained in the process gas can be evenly adsorbed on the inner side of the dust-absorbing cloth 13.

[0053] It should be noted that after the process gas is cooled by the cooler 5, due to the decrease in temperature, a part of the moisture originally in a saturated state in the process gas will precipitate from the air, form liquid water, and form water droplets on the inner wall of the vent pipe 8, thereby causing the moisture inside the vent pipe 8 to rise, resulting in the process gas flowing through the vent pipe 8 entraining some moisture, and further causing the particulate matter entrained in the process gas to agglomerate. The agglomerated particulate matter is not conducive to the adsorption of the dust-absorbing cloth 13 due to the increase in weight and volume. Therefore, in this process, the process gas flowing through the vent pipe 8 from top to bottom drives the fan 30 to rotate, so that the fan 30 drives the cylinder 9 and the crushing knife 31 to rotate, and the rotating crushing knife 31 disperses the agglomerated particulate matter to avoid the agglomeration of the particulate matter entrained in the process gas.

[0054] At the same time, the process gas and the particulate matter it entrains are collected towards the area where the crushing knife 31 is located through the converging ring 41 to improve the dispersion effect of the crushing knife 31 on the agglomerated particulate matter.

[0055] Although the present disclosure has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art should understand that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above embodiments, but should be determined not only by the appended claims but also by the equivalents of the appended claims.

Claims

1. A gas external circulation system applied to a fluidized bed type silane deposition furnace, comprising a support (1), a columnar fluidized bed (2), a three-way pipe (3), a carrier (4), a cooler (5), a pressurizer (6), a heater (7), a ventilation pipe (8), an exhaust pipe (14) and an injection pipe (15); the support (1) is installed with the columnar fluidized bed (2); the columnar fluidized bed (2) is communicated with the three-way pipe (3); the support (1) is provided with the carrier (4); the carrier (4) is successively installed with the cooler (5), the pressurizer (6) and the heater (7) from top to bottom; the cooler (5), the pressurizer (6) and the heater (7) are commonly communicated with a ventilation pipe (8); the ventilation pipe (8) and the columnar fluidized bed (2) are commonly communicated with an exhaust pipe (14); the ventilation pipe (8) and the three-way pipe (3) are commonly communicated with an injection pipe (15); characterized in that: It also includes a cylinder (9), a mounting bracket (10), a rotating roller (11), a driving motor (111), a rotating rod (12), a dust-absorbing cloth (13), a cleaner (18), an annular bracket (19) and a pressing roller (191); the ventilation pipe (8) is divided into upper, middle and lower sections, and a mounting bracket (10) is fixedly connected between every two adjacent sections; the middle section of the ventilation pipe (8) is arranged in a "C" shape; a cylinder (9) is arranged inside the middle section of the ventilation pipe (8), and there is a gap between the cylinder (9) and the middle section of the ventilation pipe (8); several symmetrically distributed rotating rollers (11) are rotatably connected by all the mounting brackets (10) together; several driving motors (111) are installed on the upper section of the ventilation pipe (8), and the driving motors (111) correspond to the rotating rollers (11) one by one, and the output shafts of each driving motor (111) are fixedly connected to the corresponding rotating rollers (11) on the corresponding side; several annularly distributed rotating rods (12) are rotatably connected by all the mounting brackets (10) together; a double-layer "C" shaped dust-absorbing cloth (13) is driven and connected by all the rotating rollers (11) and the rotating rods (12) together, and the double-layer "C" shaped dust-absorbing cloth (13) covers the middle section of the ventilation pipe (8); each mounting bracket (10) is fixedly connected with an annular bracket (19); several annularly distributed pressing rollers (191) are rotatably connected to each annular bracket (19), and the pressing rollers (191) are in contact with the dust-absorbing cloth (13); a cleaner (18) is installed on the upper section and the lower section of the ventilation pipe (8) together, and the cleaner (18) covers the dust-absorbing cloth (13).

2. The gas external circulation system applied to a fluidized bed type silane deposition furnace according to claim 1, wherein: It also includes an electric push rod (16) and an arc-shaped pressing plate (17); several vertically arrayed electric push rods (16) are installed on the bearing bracket (4); the telescopic parts of all the electric push rods (16) are fixedly connected with an arc-shaped pressing plate (17) together, and the arc-shaped pressing plate (17) is in contact with the dust-absorbing cloth (13); the length of the arc-shaped pressing plate (17) is greater than that of the dust-absorbing cloth (13), and the parts of the arc-shaped pressing plate (17) extending beyond the dust-absorbing cloth (13) at both ends are in contact with the upper section and the lower section of the ventilation pipe (8) respectively.

3. A gas external circulation system applied to a fluidized bed type silane deposition furnace according to any one of claims 1-2, characterized in that: Several fine hairs are arranged on the surface of the dust-absorbing cloth (13).

4. The gas external circulation system applied to a fluidized bed type silane deposition furnace according to claim 3, characterized in that: The dust-absorbing cloth (13) is provided with several vertically arrayed guiding convex strips (20), and the guiding convex strips (20) are made of dust-absorbing material; the guiding convex strips (20) have the ability of elastic deformation.

5. The gas external circulation system applied to a fluidized bed type silane deposition furnace according to claim 4, characterized in that: The cylinder (9) is provided with several vertically arrayed frustum-shaped guiding rings (21), and the frustum-shaped guiding rings (21) and the guiding convex strips (20) are arranged in a staggered manner.

6. The gas external circulation system applied to a fluidized bed type silane deposition furnace according to claim 5, characterized in that: A fan (30) is installed on the lower section of the ventilation pipe (8), and the rotating shaft of the fan (30) is fixedly connected with the cylinder (9), and the cylinder (9) is connected with the lower section of the ventilation pipe (8) through the fan (30).

7. The gas external circulation system applied to a fluidized bed type silane deposition furnace according to claim 6, characterized in that: The cylinder (9) is installed with a crushing knife (31), and the crushing knife (31) is close to the upper section of the ventilation pipe (8).

8. The gas external circulation system applied to a fluidized bed type silane deposition furnace according to claim 7, characterized in that: A flow dividing column (40) is fixedly connected inside the upper section of the ventilation pipe (8), and there is a gap between the flow dividing column (40) and the upper section of the ventilation pipe (8).

9. The gas external circulation system applied to a fluidized bed type silane deposition furnace according to claim 8, wherein: A funnel-shaped flow concentrating ring (41) is fixedly connected inside the upper section of the vent pipe (8), and the flow concentrating ring (41) is located below the flow dividing column (40), and the flow concentrating ring (41) cooperates with the crushing knife (31).

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