A reduction furnace bell jar

Abstract

The utility model provides a kind of reduction furnace bell jar, it is related to reduction furnace technical field, it includes: bell jar body, it includes bell jar inner wall and bell jar outer wall, cooling cavity is had between bell jar inside and bell jar outer wall;Multiple communication holes are opened with the central axis of its own as rotating shaft circumferentially on the side wall surface of bell jar inner wall;Multiple nozzles are respectively arranged in the inside of each communication hole;The outlet of each nozzle is towards the inside of reduction furnace, and the inlet is towards bell jar outer wall;Inlet of each nozzle is equipped with the feed pipe located in communication, and each feed pipe is located in the inside of cooling cavity;The other end of each feed pipe extends to the outside of bell jar by cooling cavity;Wherein, multiple communication holes are all at the middle lower part position of bell jar body, and adjacent communication holes are set apart 90 ° on the radial plane of bell jar body, and the middle lower part position of this reduction furnace bell jar increases multiple nozzles, improves silicon rod deposition uniformity and reduces the rate of pouring furnace.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of reduction furnace, concretely relates to a reduction furnace bell jar. BACKGROUND

[0002] At present, in the production process of polysilicon, the reduction furnace adopts the bottom-in bottom-out gas inlet mode, that is, the material enters from the bottom nozzle, and the tail gas is discharged from the bottom. This mode can cause the formation of airflow from bottom to top in the furnace. Because the density of the cold raw material gas mixed with trichlorosilane and hydrogen is large, it is difficult to fully rise to the top of the silicon rod, which can cause the following two situations:

[0003] 1. The airflow speed near the nozzle is high (up to 20 m / s), which can impact the middle and lower parts of the silicon rod, causing the deposition layer in this area to be loose and grow slowly, and even causing the silicon rod to sway due to airflow impact;

[0004] 2. The top of the silicon rod (especially the beam part) is prone to form a "thin neck" with a fragile structure due to insufficient gas diffusion and low material concentration, which can increase the risk of furnace reversal. SUMMARY

[0005] The utility model discloses a reduction furnace bell jar to solve the problem that the silicon rod growth is affected because the nozzles of the reduction furnace are mostly arranged at the bottom of the reduction furnace. By increasing multiple nozzles at the middle and lower parts of the reduction furnace bell jar, the deposition uniformity of the silicon rod is improved, and the furnace reversal rate is reduced.

[0006] The utility model adopts the technical scheme of:

[0007] A reduction furnace bell jar is provided, which comprises:

[0008] A bell jar body comprising an inner wall and an outer wall, a cooling cavity between the inner wall and the outer wall; a plurality of communication holes are formed on the side wall surface of the inner wall with the central axis as the rotation axis; a plurality of nozzles are arranged inside each communication hole; the outlet of each nozzle faces the inside of the reduction furnace, and the inlet faces the outer wall; a feeding pipe is arranged at the inlet of each nozzle, and each feeding pipe is located inside the cooling cavity; the other end of each feeding pipe extends to the outside of the bell jar through the cooling cavity; wherein, the plurality of communication holes are located at the middle and lower parts of the bell jar body, and the adjacent communication holes are arranged at an interval of 90° on the radial plane of the bell jar body.

[0009] Optionally, the outlet of each nozzle facing the inside of the reduction furnace is flush with the inner surface of the inner wall facing the inside of the reduction furnace.

[0010] Optionally, the adjacent communication holes are crosswise arranged in the direction of rotation of the bell jar body with the central axis as the rotation axis.

[0011] Optionally, the elevation angle of the part of the nozzles located at the middle part of the side wall surface of the inner wall of the bell jar is 25-40 degrees, and the elevation angle of the rest of the nozzles located at the bottom part of the side wall surface of the inner wall of the bell jar is 0-10 degrees.

[0012] Optionally, a corrugated pipe is arranged on the outer wall surface of each feeding pipe inside the corresponding communication hole for radial displacement compensation of the feeding pipe.

[0013] Optionally, a graphite packing is arranged on the outer wall surface of each corrugated pipe and abuts against the inner wall surface of the inner wall of the bell jar at the communication hole for radial sealing of the feeding pipe between the communication hole and the inner wall of the bell jar.

[0014] Optionally, an expansion joint is arranged at the part of each feeding pipe outside the bell jar body for axial displacement compensation of the feeding pipe when it is heated and elongated.

[0015] Optionally, a ceramic fiber gasket is arranged inside the inner wall of the bell jar at each communication hole for blocking the heat conduction path between the nozzle and the inner wall of the bell jar.

[0016] Optionally, a tungsten carbide coating is arranged on the inner wall surface of each feeding pipe.

[0017] Optionally, an observation port is arranged on the side wall surface of the outer wall of the bell jar, and a quartz glass observation window is arranged inside the observation port.

[0018] The beneficial effects of the present application are as follows:

[0019] A plurality of communication holes are circumferentially arranged on the inner wall of the bell jar of the bell jar body with the central axis of the inner wall as the rotation axis, the plurality of communication holes are distributed at the middle and lower parts of the side wall surface of the inner wall, and the adjacent communication holes are separated by 90 degrees, and a nozzle is arranged inside each communication hole, that is, compared with the traditional reduction furnace in which the nozzles are concentrated at the bottom for material spraying, a plurality of nozzles are additionally arranged, the part of the nozzles can effectively increase the speed of the silicon rods at the bottom of the reduction furnace, and the silicon core is stable, and the initial silicon core is prevented from being broken. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 It is a front view structural schematic diagram of a reduction furnace bell jar disclosed in the present embodiment.

[0022] Figure 2Fig. 1 is a schematic view of a bell-shaped body according to the present application; Figure 1 Fig. 2 is a partial enlarged view of the center A in Fig. 1;

[0023] Figure 3 Fig. 3 is a schematic view of a bell-shaped body according to the present application; Figure 1 Fig. 4 is a partial enlarged view of the center B in Fig. 3;

[0024] Figure 4 Fig. 5 is a schematic view of a bell-shaped body according to the present application;

[0025] Reference signs:

[0026] 1-bell-shaped body, 10-inner wall of the bell-shaped body, 11-outer wall of the bell-shaped body, 12-cooling cavity;

[0027] 2-bottom plate;

[0028] 3-nozzle, 30-feeding pipe;

[0029] 4-bellow;

[0030] 5-graphite packing;

[0031] 6-expansion joint;

[0032] 7-ceramic fiber gasket. DETAILED DESCRIPTION

[0033] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0034] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0035] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0036] Embodiment

[0037] Please refer to Figures 1-4As shown in the figure, this embodiment discloses a reduction furnace bell jar, including a bell jar body 1 and multiple nozzles 3. Specifically, the bell jar body 1 includes a bell jar inner wall 10 and a bell jar outer wall 11. There is a cooling cavity 12 between the bell jar inner wall 10 and the bell jar outer wall 11. When used in cooperation with a reduction furnace, the bell jar body 1 is arranged on the chassis 2 of the reduction furnace. A plurality of communication holes are circumferentially formed on the side wall surface of the bell jar inner wall 10 with its own central axis as the rotation axis. The plurality of communication holes are distributed on the middle and lower part side wall surfaces of the bell jar inner wall 10, and the adjacent communication holes are separated by 90°, that is, the number of communication holes is 4. A nozzle 3 is provided inside each communication hole, and the nozzle 3 is connected to the bell jar inner wall 10 by means of welding or flange. The outlet of the nozzle 3 faces the inside of the reduction furnace, and the inlet faces the direction of the bell jar outer wall 11. A feed pipe 30 is connected to the inlet of the nozzle 3. The feed pipe 30 does not penetrate the bell jar outer wall 11 but is distributed inside the cooling cavity 12. And the other end of the feed pipe 30 penetrates through one end of the bell jar body 1 close to the chassis 2 and extends out. The extended feed pipe 30 also penetrates and extends into the chassis 2, that is, the feed pipe 30 needs to enter the cooling cavity 12 of the bell jar body 1 from the chassis 2 to feed the nozzle 3. Since during the use of the reduction furnace, a jacket for cooling is provided on the outer wall surface of the bell jar body 1. If the feed pipe 30 penetrates the bell jar outer wall 11 and extends to the outside of the bell jar body 1, it will penetrate the jacket. Then during the use of the reduction furnace, there may be a situation where the cooling medium in the jacket leaks. Therefore, the feed pipe 30 is placed in the cooling cavity 12 between the bell jar inner wall 10 and the bell jar outer wall 11, making the overall structure relatively compact. It can not only avoid occupying the furnace body space when the feed pipe 30 is laid outside the bell jar body 1, but also indirectly cool the feed pipe 30 through the bell jar outer wall 11, reducing the risk of high-temperature creep.

[0038] Based on the above piping method of the feed pipe 30, most of the traditional nozzle 3 layout methods are distributed at the position of the chassis 2 of the reduction furnace, that is, the bottom-in and bottom-out air intake method, which will cause an upward airflow to form inside the reduction furnace. Since the cold raw material gas mixture of trichlorosilane and hydrogen has a relatively high density, it is difficult to fully rise to the top of the silicon rod. There will be a high airflow velocity near the nozzle 3 at the chassis 2, impacting the middle and lower parts of the silicon rod, resulting in slow deposition layer transportation and growth in this area, and even causing the silicon rod to shake due to the airflow impact. In addition, there will be a low material concentration and a slow deposition rate at the top of the silicon rod due to insufficient gas diffusion, and it is easy to form a structurally fragile "neck", increasing the risk of furnace tipping. Based on this, in this embodiment, a plurality of communication holes are formed on the side wall surface of the middle and lower parts of the bell jar inner wall 10, and a nozzle 3 is provided at each communication hole to blow air into the reduction furnace, compensating for the defect that the air intake at the bottom of the reduction furnace in the traditional jetting method is difficult to reach the top.

[0039] Furthermore, in this embodiment, the four connecting holes on the inner wall 10 of the bell jar are distributed in a crisscross pattern along the direction of rotation of the central axis of the inner wall 10 of the bell jar. That is, the first connecting hole is located on the middle side wall of the inner wall 10 of the bell jar, and the second connecting hole is located on the lower side wall of the inner wall 10 of the bell jar. This cycle continues, with adjacent connecting holes still spaced 90° apart. This distribution of connecting holes can form a stepped gas supply in the reduction furnace. That is, the bottom gas flow ejected by the nozzle 3 located on the side wall of the inner wall 10 of the bell jar near its own bottom impacts the root of the silicon rod, enhancing the initial deposition intensity. The middle gas flow ejected by the nozzle 3 located on the side wall of the inner wall of the bell jar near its own middle section covers the middle and upper section of the silicon rod, suppressing the occurrence of the "neck" phenomenon. The two gas flows converge to form an upward spiral flow, improving the radial diffusion efficiency. Compared with the connecting holes distributed circumferentially on the same plane, this can avoid the "waist drum" growth imbalance caused by excessive middle gas flow.

[0040] Furthermore, the end face of each nozzle 3 facing the reduction furnace is flush with the inner surface of the bell jar facing the reduction furnace. During the operation of the reduction furnace, silicon powder is generated inside. If the end face of the nozzle 3 at the outlet exceeds the inner surface of the bell jar inner wall 10 and extends into the interior of the reduction furnace, silicon powder will accumulate at the angle between the nozzle 3 and the bell jar inner wall 10. This will affect product quality, reduce the heat transfer efficiency inside the reduction furnace, and cause localized high-temperature oxidation or chemical corrosion of the equipment due to the accumulation. In addition, in this embodiment, the feed pipe 30 is made of Hastelloy C276 or 310S heat-resistant steel.

[0041] During the setting of the nozzle 3 in the above-mentioned connecting hole, the elevation angle of the nozzle 3 located in the middle of the connecting hole in the inner wall 10 of the bell is 25° to 40°, and the elevation angle of the nozzle 3 located in the bottom connecting hole inside the bell is 0° to 10°. Specifically, in this embodiment, the reference system is defined as follows: the plane where the reduction furnace chassis 2 is located is the horizontal reference plane, that is, the 0° horizontal plane, and the angle between the center line of the nozzle 3 and the horizontal plane is defined as the elevation angle. Based on the above definition of elevation angle, for the nozzle 3 located in the middle of the inner wall 10 of the bell jar, the angle between the central axis of the nozzle 3 and the 0° horizontal plane is the elevation angle. Within this elevation angle range, it is mainly used to compensate for the 2.5 to 3.5m height range that the airflow of the bottom nozzle 3 cannot reach, and can cooperate with the airflow at the bottom to form a stepped air field, promoting the deposition and molding of silicon rods in the middle and upper parts. For the nozzle 3 located at the bottom of the inner wall 10 of the bell jar, the inner wall 10 of the bell jar is almost vertical, and the angle between the airflow direction of the nozzle 3 and the radial direction of the bell jar is the elevation angle. Within this elevation angle range, the airflow climbs along the surface of the silicon rod, forming an "air film effect", improving the coverage of the middle and lower parts, and thus improving the silicon rod deposition rate.

[0042] A corrugated pipe 4 is provided on the outer wall of each feed pipe 30. Specifically, in this embodiment, the corrugated pipe 4 is a spiral corrugated pipe 4, which can accommodate both axial and radial changes. The corrugated pipe 4 is welded onto the outer wall of the feed pipe 30 to compensate for axial displacement. During the operation of the reduction furnace, the temperature inside the furnace gradually increases, causing thermal expansion of the feed pipe 30, which then moves radially. In this process, the corrugated pipe 4 on the outer wall of the feed pipe 30 can compensate for the radial displacement of the feed pipe 30. That is, the corrugated pipe 4 absorbs the deformation caused by the thermal expansion of the feed pipe 30 through radial compression or extension, preventing the feed pipe 30 wall from cracking or breaking due to stress concentration. It is worth noting that the corrugated pipe 4 is only used for radial displacement compensation of the portion of the feed pipe 30 located inside the connecting hole. In addition, vibrations will occur during the operation of the reduction furnace. The bellows 4 can reduce the amplitude of vibration transmitted to the feed pipe 30, thereby reducing the impact on the feed pipe 30.

[0043] Furthermore, graphite packing 5 is provided on the outer wall of each bellows 4. The graphite packing 5 is pressed against the bellows 4 and the inner wall of the bell jar 10 located in the connecting hole of the feed pipe 30. Specifically, the graphite packing 5 is made of graphite wire reinforced with various reinforcing fibers, metal wires (steel wire, copper wire, nickel wire, carbon fiber, pre-oxidized fiber, glass yarn, etc.). The graphite packing 5 is suitable for dynamic sealing under high temperature and high pressure conditions. For the feed pipe 30 that undergoes thermal expansion, when the feed pipe 30 moves in its own radial direction, the gap between the bellows 4 on the outer wall of the feed pipe 30 and the inner wall of the bell jar 10 located in the connecting hole will change. The graphite packing 5 can then dynamically seal the gap between the bellows 4 and the connecting hole according to the changes in the feed pipe 30 and the bellows 4.

[0044] A ceramic fiber gasket is installed inside each connecting hole on the inner wall 10 of the bell jar. The ceramic fiber gasket is a high-temperature industrial sealing element made of aluminum silicate fiber as the main material. It has the characteristics of strong thermal shock resistance and low thermal conductivity. When used at the connection between the nozzle 3 and the inner wall 10 of the bell jar, it can block the heat conduction path and prevent the temperature inside the connecting hole from being too high.

[0045] An expansion joint 6 is provided at the other end of the feed pipe 30 away from the connecting hole. The expansion joint 6 is a flexible element that can effectively compensate for axial deformation. Specifically, in this embodiment, the feed pipe 30 extends from the chassis 2 and enters the cooling chamber 12 of the bell body 1. During the operation of the reduction furnace, due to factors such as vibration and thermal expansion, the gap between the bell body 1 and the chassis 2 will change, and the feed pipe 30 located between the bell body 1 and the chassis 2 will be affected. Based on this, an expansion joint 6 is provided at the feed pipe 30 located at this gap to alleviate the axial deformation caused by the gap change.

[0046] A tungsten carbide coating (not shown in the figure) is provided on the inner wall surface of each feed pipe 30. The tungsten carbide coating has the advantages of high strength and wear resistance, which can prevent silane / chlorosilane from condensing and corroding the pipe wall when the reduction furnace is shut down. In addition, an observation port (not shown in the figure) is provided on the side wall surface of the outer wall 11 of the bell jar. A quartz glass observation window is provided at the observation port to observe the actual operating status of the feed pipe 30.

[0047] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Without conflict, the embodiments and features described in the embodiments of this application can be arbitrarily combined with each other. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bell jar for a reduction furnace, characterized in that, include: The bell jar body includes an inner wall and an outer wall, with a cooling cavity between the inner wall and the outer wall; the inner wall of the bell jar has multiple connecting holes circumferentially arranged on its own central axis as the axis of rotation. Multiple nozzles are respectively disposed inside each of the connecting holes; the outlet of each nozzle faces the interior of the reduction furnace, and the inlet faces the outer wall of the bell jar; each nozzle has a feed pipe located in the connecting hole at its inlet, and each feed pipe is located inside the cooling chamber; the other end of each feed pipe extends through the cooling chamber to the exterior of the bell jar; The multiple connecting holes are all located in the lower middle part of the bell body, and adjacent connecting holes are spaced 90° apart on the radial plane of the bell body.

2. The bell jar of the reduction furnace according to claim 1, characterized in that, The outlet of each nozzle facing the inside of the reduction furnace is flush with the inner surface of the bell jar facing the inside of the reduction furnace.

3. The bell jar of the reduction furnace according to claim 2, characterized in that, The adjacent connecting holes are arranged intersectingly in the direction in which the bell body rotates about the central axis.

4. The bell jar of the reduction furnace according to claim 1 or 3, characterized in that, The elevation angle of some nozzles located in the middle of the side wall of the inner wall of the bell jar is 25° to 40°, and the elevation angle of the remaining nozzles located at the bottom of the side wall of the inner wall of the bell jar is 0° to 10°.

5. The bell jar of the reduction furnace according to claim 1, characterized in that, Each of the feed pipes has a corrugated pipe on the outer wall surface inside the corresponding connecting hole for radial displacement compensation of the feed pipe.

6. The bell jar of the reduction furnace according to claim 5, characterized in that, Each of the bellows has a graphite packing on its outer wall surface that abuts against the inner wall surface of the bell jar at the connecting hole, for radial sealing of the feed pipe between the connecting hole and the inner wall of the bell jar.

7. The bell jar of the reduction furnace according to claim 1, characterized in that, Each of the feed tubes located outside the bell jar body is provided with a communicating expansion joint for axial displacement compensation when the feed tube expands due to heat.

8. The bell jar of the reduction furnace according to claim 1, characterized in that, The inner wall of the bell jar is provided with ceramic fiber gaskets inside each of the connecting holes to block the heat conduction path between the nozzle and the inner wall of the bell jar.

9. The bell jar of the reduction furnace according to claim 1, characterized in that, Each of the feed tubes has a tungsten carbide coating on its inner wall surface.

10. The bell jar of the reduction furnace according to claim 1, characterized in that, An observation port is provided on the side wall of the outer wall of the bell jar, and a quartz glass observation window is provided inside the observation port.

Images