Granular silicon surface multi-stage powder removing device

Abstract

The utility model provides a multi-stage powder removing device for a particle silicon surface. The device comprises more than two dust removing chambers which are sequentially arranged from top to bottom, the uppermost dust removal chamber is provided with a feed port for feeding granular silicon materials, the lowermost dust removal chamber is provided with a bottom discharge port, and every two adjacent dust removal chambers are communicated through a communication port; each dust removal chamber is provided with a bottom air inlet and a top air outlet; a stirring mechanism is arranged in each dust removal chamber, and rotates to stir particle silicon in the dust removal chambers, so that the particle silicon rubs with one another, and the rubbed particle silicon is conveyed downwards through a communicating port and finally discharged from a bottom discharge port; and airflow is upwards blown into the corresponding dust removal chamber through the bottom air inlet, and carries powder generated by friction of particle silicon to flow out from the top air outlet.

Description

Technical Field

[0001] The utility model relates to the technical field of surface treatment of granular silicon products, in particular to a multi-stage powder removal device for the surface of granular silicon. Background Art

[0002] Granular silicon is produced by chemical vapor deposition in a fluidized bed. Specifically, the silane gas in the fluidized bed decomposes at high temperature, and the generated silicon grows on the surface of the seed crystal, eventually growing into granular polycrystalline silicon with an average particle size of about 1-2 mm.

[0003] The decomposition of silane is usually based on two different mechanisms: the isochronous mechanism and the homogeneous mechanism. In the isochronous mechanism, silane decomposes on the surface of polycrystalline silicon particles, solid silicon is deposited on the surface of the particles and hydrogen is released. In the homogeneous mechanism, silane decomposes in the gas phase to release hydrogen and aerosol silicon particles, some of which are adsorbed by the polycrystalline silicon particles, while the other part is discharged from the reactor with the exhaust gas in the form of fine powder and ultrafine powder.

[0004] The surface of granular silicon produced by silane decomposition is not as dense as rod-shaped silicon. Under an electron microscope, the surface is relatively sparse and irregular, with a large number of ultrafine particles gathered. These ultrafine particles are silicon powder. Compared with spherical granular silicon of about 1-2mm, the surface area of ​​ultrafine silicon powder is much higher than that of granular silicon itself, and the content of metal impurities on its surface is also much higher than that of granular silicon.

[0005] If the granular silicon produced by silane decomposition is directly put into subsequent use, the metal impurities on its surface will increase extremely, causing the product quality to be unqualified.

[0006] In order to ensure the quality requirements of granular silicon products, the granular silicon material produced in the fluidized bed reactor must be freed of ultrafine silicon powder attached to the surface.

[0007] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the utility model, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to ordinary technicians in this field. Utility Model Content

[0008] Purpose of the utility model: The technical problem to be solved by the utility model is to provide a multi-stage powder removal device for the surface of granular silicon in view of the deficiencies in the prior art, which can continuously remove ultrafine particles on the surface of granular silicon.

[0009] In order to solve the above technical problems, the utility model discloses a multi-stage powder removal device for the surface of granular silicon, including more than two dust removal chambers arranged in sequence from top to bottom. The uppermost dust removal chamber is provided with a feed port for the entry of granular silicon materials, and the lowermost dust removal chamber is provided with a bottom discharge port, and the two adjacent dust removal chambers are connected through connecting ports. Each of the dust removal chambers has a bottom air inlet and a top air outlet. A stirring mechanism is provided in each of the dust removal chambers, and the stirring mechanism rotates to cause friction between the granular silicon in the dust removal chamber and transmits the frictional granular silicon downward through the connecting port to finally be discharged from the bottom discharge port. The airflow is blown upward into the corresponding dust removal chamber through the bottom air inlet, and flows out from the top air outlet carrying the powder generated by the friction of the granular silicon.

[0010] Furthermore, the device also includes a power unit, and the power unit is used to drive the stirring mechanism to rotate.

[0011] Specifically, the stirring mechanism comprises:

[0012] A stirring shaft is vertically arranged and rotatably arranged in the corresponding dust removal chamber;

[0013] And two groups of stirring rods are respectively arranged on both sides of the stirring shaft, each group of stirring rods includes more than two stirring rods arranged at intervals along the length direction of the stirring shaft.

[0014] Specifically, the stirring shafts in the two or more dust removal chambers are combined into an integrated structure from top to bottom; and the stirring rod is made of a single crystal silicon rod.

[0015] Furthermore, the inner wall of each dust removal chamber is provided with an inner lining layer; the inner lining layer is made of polyurethane material.

[0016] Specifically, the power unit includes a motor and a reducer, and the reducer connects the motor and the stirring shaft.

[0017] Specifically, the number of the dust removal chambers is three.

[0018] Specifically, from top to bottom, the bottom areas of the two or more relatively closed dust removal chambers gradually increase.

[0019] Specifically, each of the dust removal chambers includes an outer cylinder, an inner cylinder sleeved in the outer cylinder, an inner cylinder bottom plate arranged at the bottom of the inner cylinder, an upper sealing ring and a lower sealing ring; the upper sealing ring is sleeved between the upper part of the outer wall of the inner cylinder and the outer cylinder, and the lower sealing ring is sleeved between the lower part of the outer wall of the inner cylinder and the outer cylinder.

[0020] Specifically, the dust removal chamber at the top includes an upper flange cover, which covers the top of the outer cylinder of the corresponding dust removal chamber to achieve relative closure of the top dust removal chamber; flanges are provided at both ends of the outer cylinder, and the outer cylinders in two adjacent dust removal chambers are connected by flanges.

[0021] Beneficial effects:

[0022] 1) The multi-stage dust removal device for the granular silicon surface provided by the utility model adopts a multi-stage dust removal design, which can effectively remove the dust formed by the detachment of the conveyed silicon powder on the surface of the granular silicon due to the friction between the granular silicon during the rotation and stirring of the granular silicon by the stirring mechanism. The powder is carried out by the airflow blowing through the granular silicon from bottom to top, thereby realizing the granular silicon surface powder removal function and improving the purity of the granular silicon.

[0023] 2) At the same time, the convenience of equipment operation and maintenance is optimized. This equipment can efficiently, safely and in large quantities remove powder from granular silicon. Nitrogen is used for air intake to avoid oxidation of the granular silicon surface and the risk of explosion caused by a large amount of dust. Each unit of this equipment can process about 0.5 tons of granular silicon material per hour, which is larger than the previous equipment.

[0024] 3) The utility model can operate continuously and in multiple stages. At present, most granular silicon powder removal equipment is intermittent operation. The characteristics of intermittent operation are that after each batch of powder removal is completed, the equipment must be stopped and the materials in the equipment must be discharged before the next batch of materials can be fed, and there are a lot of disassembly and assembly operations. In order to achieve the purpose of continuous operation and high efficiency, the utility model adopts the idea of ​​single-stage feeding and multi-stage powder removal to solve the defects of current powder removal equipment in this regard.

[0025] 4) All equipment is closed, which reduces a lot of disassembly and assembly processes, ensures that the production process is environmentally friendly, reduces the impact on the environment, and complies with the modern industrial green production concept.

[0026] 5) The use of multi-stage dust removal technology also effectively reduces the number of dynamic sealing points of rotating equipment and reduces the escape of dust. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods, and the above and / or other advantages of the present invention will become more clear.

[0028] Figure 1 It is a main cross-sectional view of a multi-stage powder removal device for the surface of granular silicon disclosed in one embodiment of the utility model.

[0029] The description of the accompanying drawings is:

[0030] 1. Dust removal chamber; 11. Outer cylinder; 12. Inner cylinder; 13. Upper sealing ring; 14. Lower sealing ring; 15. Upper flange cover; 16. Flange; 17. Inner cylinder bottom plate; 2. Bottom air inlet; 21. Air inlet pipe; 3. Top air outlet; 4. Feed inlet; 41. Feed pipe; 5. Bottom discharge port; 6. Connecting port; 7. Stirring mechanism; 71. Stirring shaft; 72. Stirring rod; 8. Power unit; 81. Motor; 82. Reducer; 9. Discharge flange. DETAILED DESCRIPTION

[0031] The surface of granular silicon produced by silane decomposition is not as dense as rod-shaped silicon. Under an electron microscope, the surface is relatively sparse and irregular, with a large number of ultrafine particles gathered. These ultrafine particles are silicon powder. Compared with spherical granular silicon of about 1-2mm, the surface area of ​​ultrafine silicon powder is much higher than that of granular silicon, and the content of metal impurities on its surface is also much higher than that of granular silicon.

[0032] If the granular silicon produced by silane decomposition is directly put into subsequent use, the metal impurities on its surface will increase extremely, causing the product quality to be unqualified.

[0033] Based on this, see Figure 1 The utility model discloses a multi-stage powder removal device for the surface of granular silicon, which includes a relatively closed dust removal chamber 1, a bottom air inlet 2, a top air outlet 3, a feed port 4, a bottom discharge port 5, a connecting port 6 and a stirring mechanism 7. There are more than two dust removal chambers 1, and the more than two dust removal chambers 1 are arranged in sequence from top to bottom. The top dust removal chamber 1 is provided with a feed port 4 for the entry of granular silicon materials, and the bottom dust removal chamber is provided with a bottom discharge port 5. The two adjacent dust removal chambers 1 are connected through the connecting port 6. Each dust removal chamber 1 has a bottom air inlet 2 and a top air outlet 3, respectively, and the bottom air inlet 2 and the top air outlet 3 are connected inside the dust removal chamber 1 to form an air flow channel. A stirring mechanism 7 is provided in each dust removal chamber 1, and the stirring mechanism 7 rotates and stirs the granular silicon in the dust removal chamber 1, so that the granular silicon rubs against each other and transmits the rubbed granular silicon downward through the connecting port 6, so as to finally be discharged from the bottom discharge port 5. The friction between the granular silicon will cause the loose silicon powder on the surface of the granular silicon to fall off and form powder. The airflow can be blown upward into the corresponding dust removal chamber 1 through the bottom air inlet 2, taking away the powder generated by the friction of the granular silicon and then flowing out from the top air outlet 3.

[0034] Figure 1 In the figure, the dotted arrows represent the flow direction and trajectory of materials such as air flow or granular silicon.

[0035] In some embodiments, see Figure 1The stirring mechanism 7 includes a stirring shaft 71 and two groups of stirring rods 72 respectively arranged on both sides of the stirring shaft 71. The stirring shaft 71 is vertically arranged and rotatably arranged in the corresponding dust removal chamber 1. Each group of stirring rods 72 includes more than two stirring rods 72 spaced apart along the length direction of the stirring shaft 71.

[0036] In some embodiments, see Figure 1 , the stirring rod 72 is made of a single crystal silicon rod to avoid the introduction of impurities.

[0037] In some embodiments, see Figure 1 The stirring shafts 71 in more than two dust removal chambers 1 are combined into an integrated structure from top to bottom.

[0038] This embodiment allows the use of a set of power units to drive the agitator shafts 71 by combining the plurality of agitator shafts 71 into an integrated structure from top to bottom.

[0039] In some embodiments, see Figure 1 The inner wall of the dust removal chamber 1 is provided with an inner lining layer. In some embodiments, the inner lining layer is made of a clean polyurethane material that meets the processing requirements of photovoltaic-grade polycrystalline silicon.

[0040] In this embodiment, an inner lining layer is provided. The inner lining layer is a high-purity non-metallic material. Its function is to protect silicon from direct contact with the cylinder of the device and reduce the pollution caused by metal impurities.

[0041] In some embodiments, see Figure 1 The device further comprises a power unit 8, which is used to drive the stirring mechanism 7 to rotate. In some embodiments, the power unit 8 comprises a motor 81 and a reducer 82, and the reducer 82 connects the motor 81 and the stirring shaft 71. In some embodiments, the power unit 8 is installed at the top of the uppermost dust removal chamber 1.

[0042] In some embodiments, a dust collection and purification system is also included, which is not shown in the figure. The top air outlet 3 of each dust removal chamber 1 is connected to the dust collection and purification system. In some embodiments, the dust collection and purification system is a vacuum device.

[0043] In some embodiments, the gas is nitrogen.

[0044] In some embodiments, see Figure 1 , the number of the dust removal chambers 1 is three.

[0045] In some embodiments, the bottom areas of the two or more relatively closed dust removal chambers 1 gradually increase from top to bottom.

[0046] This embodiment adopts a gradually expanding chamber design. The design of gradually increasing the bottom area helps to improve the airflow distribution, so that the airflow speed gradually slows down when passing through different chambers, which is conducive to more thorough removal of silicon powder on the surface of granular silicon. This design can also increase the residence time of granular silicon in the chamber and improve the powder removal efficiency.

[0047] In one embodiment, see Figure 1 Each dust removal chamber 1 includes an outer cylinder 11, an inner cylinder 12 sleeved in the outer cylinder 11, an inner cylinder bottom plate 17 arranged at the bottom of the inner cylinder 12, an upper sealing ring 13 and a lower sealing ring 14. The upper sealing ring 13 is sleeved between the upper part of the outer wall of the inner cylinder 12 and the outer cylinder 11, and the lower sealing ring 14 is sleeved between the lower part of the outer wall of the inner cylinder 12 and the outer cylinder 11.

[0048] See also Figure 1 The feed port 4 is opened in the middle of the wall of the inner cylinder 12 of the uppermost dust removal chamber 1. The bottom air inlet 2 is opened in the inner cylinder bottom plate 17 of the dust removal chamber 1. The top air outlet 3 is opened in the wall of the outer cylinder 11 of the dust removal chamber 1.

[0049] See also Figure 1 The device further comprises a feed pipe 41 and an air inlet pipe 21, one end of the feed pipe 41 passes through the outer cylinder 11 and is connected to the feed port 4. One end of the air inlet pipe 21 passes through the outer cylinder 11 and is connected to the bottom air inlet 2.

[0050] In one embodiment, see Figure 1 The uppermost dust removal chamber 1 includes an upper flange cover 15 , and the upper flange cover 15 covers the top of the outer cylinder 11 of the corresponding dust removal chamber 1 .

[0051] In one embodiment, see Figure 1 Flanges 16 are provided at both ends of the outer cylinder 11, and the outer cylinders 11 in two adjacent dust removal chambers 1 are connected by the flanges 16 to realize a structure in which more than two relatively closed dust removal chambers 1 are combined into one from top to bottom.

[0052] The flange 16 at the lower end of the outer cylinder 11 in the lowest dust removal chamber 1 can be connected to the downstream process equipment through the discharge flange. After the material exits the flange 16, it becomes the dust removal material.

[0053] The utility model provides a concept and method for a multi-stage powder removal device on the surface of granular silicon. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the utility model. These improvements and modifications should also be regarded as the protection scope of the utility model. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A multi-stage powder removal device for granular silicon surface, characterized in that: The invention comprises two or more dust removal chambers (1) arranged in sequence from top to bottom; the uppermost dust removal chamber (1) is provided with a feed port (4) for allowing granular silicon material to enter, and the lowermost dust removal chamber is provided with a bottom discharge port (5), and two adjacent dust removal chambers (1) are connected via a connecting port (6); each dust removal chamber (1) has a bottom air inlet (2) and a top air outlet (3); a stirring mechanism (7) is provided in each dust removal chamber (1), and the stirring mechanism (7) rotates to cause the granular silicon in the dust removal chamber (1) to rub against each other and transfer the granular silicon after friction downward through the connecting port (6) to be finally discharged from the bottom discharge port (5); the air flow is blown upward into the corresponding dust removal chamber (1) through the bottom air inlet (2), and flows out from the top air outlet (3) carrying the powder generated by the friction of the granular silicon.

2. The multi-stage powder removal device for granular silicon surface according to claim 1, characterized in that: It also comprises a power unit (8), wherein the power unit (8) is used to drive the stirring mechanism (7) to rotate.

3. The multi-stage powder removal device for granular silicon surface according to claim 2, characterized in that: The stirring mechanism (7) comprises: A stirring shaft (71) is arranged vertically and rotatably in the corresponding dust removal chamber (1); and two groups of stirring rods (72) respectively arranged on both sides of the stirring shaft (71), each group of stirring rods (72) comprising more than two stirring rods (72) arranged at intervals along the length direction of the stirring shaft (71).

4. The multi-stage powder removal device for granular silicon surface according to claim 3, characterized in that: The stirring shafts (71) in the two or more dust removal chambers (1) are combined from top to bottom into an integrated structure; and the stirring rod (72) is made of a single crystal silicon rod.

5. The multi-stage powder removal device for granular silicon surface according to claim 1, characterized in that: The inner wall of each dust removal chamber (1) is provided with an inner lining layer; the inner lining layer is made of polyurethane material.

6. The multi-stage powder removal device for granular silicon surface according to claim 3, characterized in that: The power unit (8) comprises a motor (81) and a reducer (82), wherein the reducer (82) connects the motor (81) and the stirring shaft (71).

7. The multi-stage powder removal device for granular silicon surface according to claim 1, characterized in that: The number of the dust removal chambers (1) is three.

8. The multi-stage powder removal device for granular silicon surface according to claim 1, characterized in that: From top to bottom, the bottom areas of the two or more relatively closed dust removal chambers (1) gradually increase.

9. The multi-stage powder removal device for granular silicon surface according to claim 1, characterized in that: Each of the dust removal chambers (1) comprises an outer cylinder (11), an inner cylinder (12) sleeved in the outer cylinder (11), an inner cylinder bottom plate (17) arranged at the bottom of the inner cylinder (12), an upper sealing ring (13) and a lower sealing ring (14); the upper sealing ring (13) is sleeved between the upper part of the outer wall of the inner cylinder (12) and the outer cylinder (11), and the lower sealing ring (14) is sleeved between the lower part of the outer wall of the inner cylinder (12) and the outer cylinder (11).

10. The multi-stage powder removal device for granular silicon surface according to claim 9, characterized in that: The dust removal chamber (1) at the top comprises an upper flange cover (15), and the upper flange cover (15) covers the top of the outer cylinder (11) of the corresponding dust removal chamber (1) to achieve relative closure of the dust removal chamber (1) at the top; flanges (16) are provided at both ends of the outer cylinder (11), and the outer cylinders (11) in two adjacent dust removal chambers (1) are connected via the flanges (16).

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