Feeding device for granular silicon

Abstract

The utility model relates to a feeding device for granular silicon, which comprises a feeding cylinder, a feeding device, a feeding device, a feeding device and a discharging device, wherein a discharging opening is formed in the bottom of the feeding cylinder; the discharging bottom cover is arranged in the bottom of the feeding cylinder; the lifting mechanism is connected with the discharging bottom cover and controls the discharging bottom cover to move up and down in the feeding cylinder so as to block or open the discharging opening; the outer diameter of the discharging bottom cover is gradually increased and then gradually decreased from top to bottom; a reducing area with a reducing cylinder diameter is arranged at a position where the bottom of the charging cylinder is connected with the discharging bottom cover; in a closed state, the discharging bottom cover is tightly connected with the inner wall of the reducing area and is used for sealing particle silicon; and in a separation state, the discharging bottom cover is positioned below the necking area, and a gap is formed between the discharging bottom cover and the inner wall of the necking area, so that the granular silicon flows out and finally falls into a quartz crucible below the discharging bottom cover. The feeding device can effectively avoid silicon splashing and silicon jumping of particle silicon, and improves the single crystal forming rate.

Description

Technical Field

[0001] This application relates to the field of polycrystalline silicon preparation technology, and in particular to a feeding device for granular silicon. Background Technology

[0002] With the continuous advancement of the silane fluidized bed process, granular silicon will occupy the majority of the silicon raw material market in the future. The silane fluidized bed process for producing granular silicon has low overall energy consumption and high output, resulting in low-priced granular silicon. Currently, granular silicon is used as one of the raw materials for solar photovoltaic silicon monocrystalline silicon, and it has also become one of the effective ways to reduce the cost of solar photovoltaic silicon. The production process of granular silicon requires hydrogen to participate in the chemical reaction. Generally, the surface of the produced granular silicon will be coated with adsorbed hydrogen. Contact with molten silicon in an insufficiently heated state will cause silicon splashing and jumping phenomena, contaminating the thermal field components and reducing the crystallization rate.

[0003] Current technologies use feeding cylinders to add granular silicon. However, most existing feeding cylinders have a straight cylindrical structure. During actual feeding, the raw material falls vertically at a rapid rate, which can easily lead to cone embedding anomalies. The raw material is dispersed in a ring along the bottom support over a large area, resulting in significant silicon powder volatilization. Furthermore, the bottom support obstructs the flow of material, leaving the lower part of the support without material. This creates a concave center and convex edges, which can cause premature melting of the central raw material and lead to bubbling and splashing anomalies.

[0004] Therefore, it is necessary to develop a feeding device for granular silicon to solve the technical problems mentioned above. Utility Model Content

[0005] Based on this, a feeding device for granular silicon is provided, which can effectively avoid silicon sputtering and silicon jumping in granular silicon and improve the single crystal formation rate.

[0006] To address the above problems, this application provides a feeding device for granular silicon, comprising: a feeding cylinder with a discharge port at its bottom; a discharge bottom cover disposed within the bottom of the feeding cylinder; and a lifting mechanism connected to the discharge bottom cover, which controls the discharge bottom cover to move up and down within the feeding cylinder to block or open the discharge port. The discharge bottom cover is configured such that its outer diameter gradually increases and then gradually decreases from top to bottom. A diameter-reducing zone is provided at the bottom of the feeding cylinder where it connects with the discharge bottom cover. In a closed state, the discharge bottom cover and the inner wall of the diameter-reducing zone are tightly connected to seal the granular silicon. In a separated state, the discharge bottom cover is located below the diameter-reducing zone, creating a gap with the inner wall of the diameter-reducing zone, allowing the granular silicon to flow out and ultimately fall into a quartz crucible below.

[0007] Preferably, the inner diameter of the narrowing region gradually decreases from top to bottom and then gradually increases.

[0008] Preferably, the minimum inner diameter of the reduced diameter region is located at the middle position of the reduced diameter region.

[0009] Preferably, the inner wall of the reduced diameter region is an arc surface.

[0010] Preferably, the inner diameter r1 at the lower end of the reduced diameter zone is greater than the maximum outer diameter of the discharge bottom cover; the minimum inner diameter r2 of the reduced diameter zone is equal to or less than the maximum outer diameter of the discharge bottom cover.

[0011] Preferably, the discharge bottom cover is spherical.

[0012] Preferably, the discharge bottom cover is ellipsoidal.

[0013] Preferably, the major axis of the ellipsoidal bottom cover is set vertically, and the minor axis is set horizontally.

[0014] Preferably, the bottom of the feeding cylinder is further provided with a narrowing area, the upper end of which is connected to the lower end of the diameter reduction area.

[0015] Preferably, the inner diameter of the closing area gradually decreases from top to bottom.

[0016] This application also provides a single crystal furnace, in which the aforementioned feeding device for granular silicon is used to feed granular silicon.

[0017] Beneficial effects:

[0018] The aforementioned feeding device for granular silicon uses a discharge bottom cover whose outer diameter gradually increases and then decreases from top to bottom. During the feeding process, a lifting mechanism moves the discharge bottom cover downwards until it is located below the necking section at the bottom of the feeding cylinder, creating a gap between it and the inner wall of the necking section. At this point, the granular silicon inside the feeding cylinder can enter the quartz crucible through the gap between the discharge bottom cover and the inner wall of the necking section. Due to the special outer diameter of the bottom cover, the granular silicon, guided by the lines on the upper part of the discharge bottom cover, first flows into the space between the discharge bottom cover and the inner wall of the necking section. The silicon particles are separated by gaps and then guided by the lines at the bottom of the discharge cover to gather in the middle of the discharge port. In other words, after the silicon particles enter the crucible, they are more likely to gather in the middle of the quartz crucible. Since the center of the crucible is farthest from the heater, its temperature is the lowest in the entire thermal field. The silicon particles will not melt rapidly in advance when they gather here, avoiding the volcano phenomenon and reducing the probability of furnace blockage. At the same time, it can also effectively slow down the bubbling and splashing of silicon particles, prevent the silicon liquid from splashing onto the water-cooled screen, reduce single crystal breakage, and improve the crystallization rate, thereby increasing the output per unit and achieving cost reduction and efficiency improvement. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a feeding device for granular silicon in one embodiment, with the discharge bottom cover in a closed state.

[0020] Figure 2 This is a schematic diagram of a feeding device for granular silicon in one embodiment, with the discharge bottom cover in a separated state.

[0021] Figure 3 for Figure 2 Enlarged view of part A in the image.

[0022] Reference numerals in the attached drawings: 1. Feeding cylinder; 11. Discharge port; 12. Reduction zone; 121. Arc surface; 13. Closing zone; 2. Discharge bottom cover; 3. Lifting mechanism; 31. Connecting part; 32. Protective sleeve; 4. Quartz crucible. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0024] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0025] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0026] The orientations or positional relationships indicated by terms such as "upper," "lower," "left," "right," "middle," "longitudinal," "lateral," "horizontal," "inner," "outer," "radial," and "circumferential" used in this specification are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the purpose of simplifying the description. They 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 limiting this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] This application provides a feeding device for granular silicon. The outer diameter of the discharge bottom cover inside the feeding cylinder is set to gradually increase from top to bottom and then gradually decrease, which has a guiding effect. With the help of special external lines, the granular silicon falls and is more likely to accumulate in the center of the quartz crucible, making it less likely to melt prematurely, thereby solving the problem of bubbling and splashing silicon.

[0028] The following is a detailed description of a feeding device for granular silicon provided in this embodiment, with reference to the accompanying drawings. Figure 1 , Figure 2 As shown, it includes: a feeding cylinder 1, a discharge bottom cover 2, and a lifting mechanism 3. The bottom of the feeding cylinder 1 is provided with a discharge port 11; the discharge bottom cover 2 is located inside the bottom of the feeding cylinder 1; the lifting mechanism 3 is connected to the discharge bottom cover 2 and is used to control the discharge bottom cover 2 to move up and down inside the feeding cylinder 1, blocking or opening the discharge port 11; wherein, the discharge bottom cover 2 is configured such that the outer diameter gradually increases from top to bottom and then gradually decreases; the bottom of the feeding cylinder 1 is provided with a diameter reduction zone 12 at the position where it connects with the discharge bottom cover 2; in the closed state, the discharge bottom cover 2 and the inner wall of the diameter reduction zone 12 are in close contact to seal the granular silicon; in the separated state, the discharge bottom cover 2 is located below the diameter reduction zone 12, creating a gap with the inner wall of the diameter reduction zone 12, for the granular silicon to flow out and finally fall into the quartz crucible 4 below.

[0029] During the feeding process, the lifting mechanism 3 controls the up-and-down movement of the discharge bottom cover 2 within the feeding cylinder 1. For example, if the discharge bottom cover 2 moves downward within the feeding cylinder 1 to a position below the necking area 12, a gap is created between it and the inner wall of the necking area 12. Due to the special outer diameter of the discharge bottom cover 2, the silicon particles, guided by the upper lines of the discharge bottom cover 2, first flow into the gap between the discharge bottom cover 2 and the inner wall of the necking area 12. Then, guided by the lower lines of the discharge bottom cover 2, they gather towards the middle position of the discharge port 11, thus achieving discharge. Furthermore, it is easier for the silicon particles to accumulate in the center of the quartz crucible 4. When the discharge bottom cover 2 rises, it is in close contact with the inner wall of the narrowed section 12 at the bottom of the feeding cylinder 1, at which point the silicon particles cannot flow out. Therefore, the special outer diameter structure of the discharge bottom cover 2 in this embodiment has a guiding effect, making it easier for the silicon particles to accumulate in the center of the quartz crucible 4 when falling. This can effectively reduce the bubbling and splashing of silicon particles, improve the crystallization rate, thereby increasing the production capacity. At the same time, it can also prevent the occurrence of volcano phenomenon, reduce the probability of furnace blockage accidents, and reduce costs.

[0030] Please continue to refer to Figure 1 , Figure 2As shown in this embodiment, it should be noted that the diameter reduction zone 12 is located near the bottom of the feeding cylinder 1, and its inner diameter gradually decreases and then increases from top to bottom. The minimum inner diameter of the diameter reduction zone 12 is located in the middle of the diameter reduction zone 12, and the inner wall of the diameter reduction zone 12 is an arc surface 121. The outer diameter of the discharge bottom cover 2 is set to gradually increase and then decrease from top to bottom, and the outer wall of the discharge bottom cover 2 can also be set as an arc surface. In this way, when the outer wall of the discharge bottom cover 2 and the inner wall of the diameter reduction zone 12 are tightly connected, the upper section of the discharge bottom cover 2 and the diameter reduction zone 12 together form a constricted space, which is convenient for material accumulation; the lower section of the discharge bottom cover 2 and the diameter reduction zone 12 together form a flared space, which is convenient for material discharge. In other words, the diameter reduction zone 12 is set as an inwardly convex structure, and the discharge bottom cover 2 is an outwardly convex structure. Through the connection of the outwardly convex structure and the inwardly convex structure, a tighter seal can be achieved, while also realizing the functions of material collection and discharge.

[0031] In some embodiments, the inner diameter r1 of the lower end of the narrowing zone 12 is greater than the maximum outer diameter of the discharge bottom cover 2, and the minimum inner diameter r2 of the narrowing zone 12 is equal to or less than the maximum outer diameter of the discharge bottom cover 2. This configuration ensures that the maximum outer diameter portion of the discharge bottom cover 2 can pass through the lower end of the narrowing zone 12 and enter the middle position of the narrowing zone 12 when it moves upwards. When the minimum inner diameter r2 of the narrowing zone 12 is set to be equal to the maximum outer diameter of the discharge bottom cover 2, the discharge bottom cover 2 can move upwards until the maximum outer diameter portion is tightly connected to the middle position of the narrowing zone 12, achieving a more tight seal. When the minimum inner diameter r2 of the narrowing zone 12 is set to be less than the maximum outer diameter of the discharge bottom cover 2, the discharge bottom cover 2 can move upwards until the maximum outer diameter portion is tightly connected to the middle position of the narrowing zone 12. In this case, when the discharge bottom cover 2 moves downwards, it is easier to separate from the inner wall of the narrowing zone 12, creating a gap and resulting in faster discharge. Therefore, regardless of the above situation, when the discharge bottom cover 2 moves upward to the point where its outer wall meets the inner wall of the narrowing zone 2, there is no gap between the outer wall of the discharge bottom cover 2 and the inner wall of the narrowing zone 2. Then, granular silicon can be added into the feeding cylinder 1. The granular silicon is concentrated in the narrowing space formed by the upper part of the discharge bottom cover 2 and the narrowing zone 2. When discharge is required, the discharge bottom cover 2 is controlled to move downward, so that the outer wall of the discharge bottom cover 2 and the inner wall of the narrowing zone 2 are separated, i.e., a gap is created. At this time, the granular silicon is guided to fall and concentrate in the center of the quartz crucible 4 due to the special external structure of the discharge bottom cover 2.

[0032] In some embodiments, the discharge bottom cover 2 is spherical. When the discharge bottom cover 2 is spherical, the outer line of the discharge bottom cover 2 can be understood as an outwardly convex arc surface. The arc surface of the discharge bottom cover 2 can be closely connected with the inwardly convex arc surface 121 of the diameter reduction area 12 to seal the silicon particles. Furthermore, the outwardly convex arc surface has a flow guiding effect, which enables the silicon particles to gather at the center of the quartz crucible 4 when falling.

[0033] In some embodiments, the discharge bottom cover 2 is ellipsoidal. When the discharge bottom cover 2 is ellipsoidal, the major axis a of the ellipsoid of the discharge bottom cover 2 is set vertically and the minor axis b is set horizontally. With this setting, the outer line of the discharge bottom cover 2 can be understood as an outwardly convex arc surface. The arc surface of the discharge bottom cover 2 can be closely connected with the inwardly convex arc surface 121 of the diameter reduction zone 12 to seal the particulate silicon. Furthermore, the outwardly convex arc surface has a flow guiding effect, which enables the particulate silicon to gather at the center of the quartz crucible 4 when it falls.

[0034] Please continue to refer to Figure 1 , Figure 2 As shown in this embodiment, it should also be noted that the bottom of the feeding cylinder 1 is also provided with a narrowing area 13. The upper end of the narrowing area 13 is connected to the lower end of the diameter reduction area 12, and the inner diameter of the narrowing area 13 gradually decreases from top to bottom. Through the special structural design of the narrowing area 13, the granular silicon particles after being guided by the discharge bottom cover 2 can be guided again to the middle position of the discharge port 11 to achieve discharge. After discharge, the granular silicon particles gather towards the center position of the quartz crucible 4. Preferably, the inner wall of the narrowing area 13 is also set as an arc surface. The arc surface setting can guide the falling of the granular silicon particles without jamming them.

[0035] Please refer to Figures 1-3 As shown in this embodiment, it should also be noted that the lifting mechanism 3 includes a connecting part 31. The lower end of the connecting part 31 is connected to the discharge bottom cover 2, and the upper end extends out of the feeding cylinder 1 and is connected to the crystal lifting mechanism in the auxiliary chamber of the single crystal furnace. This crystal lifting mechanism is a conventional structure in the art and will not be described in detail here. During the feeding process, the lifting mechanism is controlled to control the raising and lowering of the connecting part 31, and then the connecting part 31 is used to control the up and down movement of the discharge bottom cover 2 in the feeding cylinder 1, thereby creating a gap between it and the diameter reduction zone 12. The silicon material enters the quartz crucible 4 at the bottom through this gap. It can be understood that the descent speed and quantity of the silicon particles can be controlled by controlling the descent speed and descent distance of the connecting part 31.

[0036] In some embodiments, the connecting part 31 is configured as a connecting rod, and the connecting rod and the discharge bottom cover 2 are arranged coaxially. By using a connecting rod for the connecting part, it is more stable when the discharge bottom cover 2 is lifted, and it will not sway left and right. Furthermore, it is connected to the top center position of the discharge bottom cover 2, that is, it is arranged coaxially with the discharge bottom cover 2. When the discharge bottom cover 2 is lowered, a balanced gap can be generated between it and the diameter reduction zone 12.

[0037] In some embodiments, the connecting rod is made of molybdenum and is covered by a protective sleeve 32, preferably made of quartz. By making the connecting rod of molybdenum and covering it with a quartz protective sleeve 32, metal contamination of the silicon material can be avoided during the feeding process.

[0038] In this embodiment, a single crystal furnace is also provided, which uses the above-described feeding device for granular silicon to feed granular silicon.

[0039] The implementation principle of this embodiment is as follows: To reduce silicon sputtering and improve the crystal formation rate, this embodiment designs a feeding device for granular silicon. This device is an upgrade of the existing feeding cylinder, with the triangular conical quartz bottom cover designed as a spherical or ellipsoidal discharge bottom cover 2. Utilizing the spherical or ellipsoidal external lines and the high fluidity of granular silicon, during the feeding process, the discharge bottom cover 2 is lowered, creating a gap between the discharge bottom cover 2 and the inner wall of the diameter reduction zone 12. At this time, the granular silicon in the feeding cylinder 1... The falling path will flow along the gap. When the granular silicon flows, it can be guided by the shape of the discharge bottom cover 2 to the middle position of the discharge port 11. After discharge, the granular silicon can fall to the center of the quartz crucible 4. Since the center of the crucible is farthest from the heater, its temperature is the lowest in the entire thermal field. The granular silicon will not melt rapidly in advance, thus effectively slowing down the bubbling and splashing of granular silicon, thereby preventing the silicon liquid from splashing onto the water cooling screen, reducing single crystal breakage, improving the crystallization rate, and thus increasing the unit output to achieve cost reduction and efficiency improvement.

[0040] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A feeding device for granular silicon, characterized in that, include: Feeding cylinder (1), the bottom of which is provided with a discharge port (11); The discharge bottom cover (2) is disposed inside the bottom of the feeding cylinder (1); Lifting mechanism (3) is connected to the discharge bottom cover (2) and controls the discharge bottom cover (2) to move up and down in the feeding cylinder (1) to block or open the discharge port (11); The discharge bottom cover (2) is configured such that its outer diameter gradually increases from top to bottom and then gradually decreases; the bottom of the feeding cylinder (1) is provided with a diameter reduction area (12) where the cylinder diameter shrinks at the position where it connects with the discharge bottom cover (2); In the closed state, the discharge bottom cover (2) and the inner wall of the narrowed diameter area (12) are in close contact to seal the granular silicon; In the separated state, the discharge bottom cover (2) is located below the necking area (12) and creates a gap with the inner wall of the diameter reduction area (12) for the particle silicon to flow out and finally fall into the quartz crucible (4) below.

2. The feeding device for granular silicon according to claim 1, characterized in that, The inner diameter of the narrowing region (12) gradually decreases from top to bottom and then gradually increases.

3. The feeding device for granular silicon according to claim 2, characterized in that, The minimum inner diameter of the reduced diameter region (12) is located in the middle of the reduced diameter region (12).

4. The feeding device for granular silicon according to claim 3, characterized in that, The inner wall of the narrowed region (12) is an arc surface (121).

5. The feeding device for granular silicon according to claim 4, characterized in that, The inner diameter r1 at the lower end of the reduced diameter zone (12) is greater than the maximum outer diameter of the discharge bottom cover (2); The minimum inner diameter r2 of the reduced diameter zone (12) is equal to or less than the maximum outer diameter of the discharge bottom cover (2).

6. The feeding device for granular silicon according to claim 5, characterized in that, The discharge bottom cover (2) is spherical.

7. The feeding device for granular silicon according to claim 5, characterized in that, The discharge bottom cover (2) is ellipsoidal.

8. The feeding device for granular silicon according to claim 7, characterized in that, The ellipsoidal bottom cover (2) has its major axis set vertically and its minor axis set horizontally.

9. The feeding device for granular silicon according to claim 6 or 8, characterized in that, The bottom of the feeding cylinder (1) is also provided with a narrowing area (13), the upper end of which is connected to the lower end of the diameter reduction area (12).

10. The feeding device for granular silicon according to claim 9, characterized in that, The inner diameter of the closing area (13) gradually decreases from top to bottom.

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