Crystalline silicon growth furnace with heat preservation cover

Abstract

The utility model relates to the technical field of reduction furnaces, and provides a crystalline silicon growth furnace with a heat preservation cover, the crystalline silicon growth furnace comprises a furnace bottom assembly, a heat preservation cover assembly and a gas circulation system, the heat preservation cover assembly covers the furnace bottom assembly, the gas circulation system is arranged on the furnace bottom assembly, and the heat preservation cover assembly covers the furnace bottom assembly. An air inlet, an air outlet and an electrode mounting opening are formed in the furnace bottom assembly, the heat preservation cover assembly comprises an inner cover and an outer cover, the inner cover is a piece made of a high-temperature-resistant non-metal material, the outer cover is a piece made of a heat preservation material, and the outer side of the heat preservation cover assembly is further covered with a double-layer water-cooling metal cover. The furnace bottom assembly comprises a double-layer water-cooling metal bottom plate and a high-temperature-resistant non-metal material bottom sleeve. The heat preservation cover assembly is arranged on the inner side of the double-layer water-cooling metal cover, the heat conduction coefficient is reduced and obviously lower than that of a traditional stainless steel cover, the heat insulation performance is remarkably improved, and energy consumption is reduced; and the inner cover is a piece made of a high-temperature-resistant non-metal material, so that metal impurity pollution is effectively avoided, and the purity of the product is effectively ensured.

Description

Technical Field

[0001] This application belongs to the field of reduction furnace technology, and more specifically, relates to a silicon growth furnace with a heat insulation cover. Background Technology

[0002] Currently, stainless steel 31668T is commonly used as the lining material for polysilicon reduction furnaces in China. However, this material has significant drawbacks in practical applications: First, its thermal conductivity is high (approximately 16.3 W / (m·K)), resulting in severe heat loss inside the furnace and poor heat insulation; second, the mechanical properties of stainless steel decrease significantly under high-temperature conditions (>800℃), affecting the service life of the equipment. To improve thermal efficiency, existing technologies typically employ polishing or silver plating of the inner wall of the metal cover, but these methods have the following limitations: (1) the heat reflection effect decreases sharply after the silicon layer is deposited on the surface; (2) the plating layer is prone to oxidation failure under high-temperature conditions; (3) the surface treatment layer is prone to peeling off during cleaning and maintenance, resulting in high maintenance costs. According to statistics, the average energy consumption for producing 1 kg of polysilicon in existing reduction furnaces is as high as 50 kWh, of which approximately 35% of the energy loss is due to insufficient furnace insulation performance. In addition, traditional metal materials may release trace amounts of metal impurities under high-temperature conditions, affecting the purity of polysilicon products. Therefore, developing a high-efficiency heat-preserving reduction furnace that can effectively reduce energy consumption while ensuring the purity of silicon material has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0003] The purpose of this application is to provide a silicon growth furnace with a heat insulation cover to solve the technical problems of poor heat insulation, high energy consumption and high maintenance cost of the reduction furnace in the prior art due to the use of stainless steel furnace body without heat insulation layer. At the same time, it can effectively avoid the adverse effects of metal impurities on the purity of silicon material.

[0004] To achieve the above objectives, the technical solution adopted in this application is as follows: a silicon growth furnace with a heat insulation cover is provided, comprising: a furnace bottom assembly, a heat insulation cover assembly, and a gas circulation system. The heat insulation cover assembly is disposed on the furnace bottom assembly. The furnace bottom assembly is provided with an air inlet, an air outlet, and an electrode mounting port. The heat insulation cover assembly includes an inner cover and an outer cover. The inner cover is made of a high-temperature resistant non-metallic material, and the outer cover is made of a heat insulation material. A double-layer water-cooled metal cover is also provided on the outside of the heat insulation cover assembly. The furnace bottom assembly includes a double-layer water-cooled metal base plate and a high-temperature resistant non-metallic material base sleeve.

[0005] In one embodiment, both the high-temperature resistant non-metallic material component and the high-temperature resistant non-metallic material base sleeve are made of carbon-ceramic composite material.

[0006] In one embodiment, the heat insulation cover assembly is detachably connected to the double-layer water-cooled metal cover.

[0007] In one embodiment, both the double-layer water-cooled metal cover and the double-layer water-cooled metal base plate are made of stainless steel.

[0008] In one embodiment, the insulation material component is a carbon fiber insulation material component, a silicon carbide insulation material component, or a silicon nitride fiber insulation material component.

[0009] In one embodiment, the inner and / or outer walls of the heat insulation cover assembly are provided with reinforcing ribs.

[0010] In one embodiment, the inner cover and the outer cover are connected by screws.

[0011] In one embodiment, the heat insulation cover assembly and the double-layer water-cooled metal cover are snapped together by a snap ring structure;

[0012] In one embodiment, carbon-ceramic composite material tubes are installed at the air inlet, air outlet, and electrode mounting port.

[0013] The beneficial effects of the silicon growth furnace with insulation cover provided in this application are as follows: by setting an insulation cover assembly on the inner side of the double-layer water-cooled metal cover, the thermal conductivity is reduced and is significantly lower than that of the traditional stainless steel cover, which significantly improves the heat insulation performance and reduces energy consumption; moreover, the inner cover is made of high-temperature resistant non-metallic material, which effectively avoids metal impurity contamination and effectively ensures the purity of the product. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A simplified structural diagram of a silicon growth furnace with a heat insulation cover provided in an embodiment of this application;

[0016] Figure 2 A schematic diagram of the structure of the heat insulation cover assembly in a silicon growth furnace with a heat insulation cover provided in an embodiment of this application;

[0017] Figure 3 A cross-sectional view of the heat insulation cover assembly in a silicon growth furnace with a heat insulation cover, provided in an embodiment of this application.

[0018] Figure 4 This is a cross-sectional view of the double-layer water-cooled metal cover in a silicon growth furnace with a heat insulation cover, as provided in an embodiment of this application.

[0019] The following are the labeling elements in the figure:

[0020] 1. Inner cover; 2. Outer cover; 3. Double-layer water-cooled metal cover; 4. High-temperature resistant non-metallic material base sleeve; 5. Double-layer water-cooled metal base plate; 6. Electrode; 7. Inlet pipe; 8. Outlet pipe; 9. Carbon ceramic composite material pipe; 10. Reinforcing rib; 11. T-ring; 12. L-ring. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects to be solved by 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 are not intended to limit the scope of this application.

[0022] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0023] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and 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. Therefore, they should not be construed as limitations on this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0025] like Figures 1-4 As shown, a silicon growth furnace with a heat insulation cover according to an embodiment of this application will now be described. This silicon growth furnace with a heat insulation cover includes: a furnace bottom assembly, a heat insulation cover assembly, and a gas circulation system. The heat insulation cover assembly is disposed on the furnace bottom assembly to form a silicon growth cavity; the furnace bottom assembly is provided with an air inlet, an air outlet, and an electrode mounting port; the gas circulation system is connected to the silicon growth cavity through the air inlet and the air outlet; the electrode mounting port is used to mount electrodes 6.

[0026] In this embodiment, the insulation cover assembly includes an inner cover 1 and an outer cover 2. The inner cover 1 is made of a high-temperature resistant non-metallic material, and the outer cover 2 is made of insulation material. A double-layer water-cooled metal cover 3 is also provided on the outside of the insulation cover assembly. The furnace bottom assembly includes a double-layer water-cooled metal base plate 5 and a high-temperature resistant non-metallic material base sleeve 4. Specifically, both the high-temperature resistant non-metallic material component and the high-temperature resistant non-metallic material base sleeve 4 are made of carbon-ceramic composite material. An insulation material layer is also provided between the high-temperature resistant non-metallic material base sleeve 4 and the double-layer water-cooled metal base plate 5, so that the high-temperature resistant non-metallic material base sleeve 4 protrudes so that it can be installed in the port of the insulation cover assembly to better insulate the silicon growth cavity. The insulation material component and the insulation material layer are made of carbon fiber insulation material, silicon carbide insulation material, or silicon nitride fiber insulation material.

[0027] In this embodiment, the carbon-ceramic composite material part has the following excellent properties:

[0028] 1. Physical properties: density ≤ 2.0 g / cm³, coefficient of thermal expansion ≤ 3.5 x 10⁻⁶ -6 / ℃ (RT-1000℃);

[0029] 2. Chemical properties: Resistant to acid and alkali corrosion, with an oxidation resistance temperature ≥1200℃;

[0030] 3. Mechanical properties: Bending strength ≥ 100 MPa;

[0031] 4. Purity: The total content of all impurities (Li, Na, Al, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, W) is <100ppm.

[0032] Experimental verification shows that the heat insulation cover assembly provided in this embodiment has a significant energy-saving effect on polycrystalline silicon growth furnaces: the energy consumption of the reduction furnace to produce 1 kg of polycrystalline silicon is reduced from more than 50 kWh to less than 30 kWh, with an energy saving rate of more than 40%.

[0033] In this embodiment, the heat insulation cover assembly is detachably connected to the double-layer water-cooled metal cover 3. This facilitates the separation of the heat insulation cover assembly from the double-layer water-cooled metal cover 3 for cleaning, and the silicon layer deposited on the inner wall surface of the heat insulation cover assembly can be removed by melting at high temperature (≥1420℃) or soaking in alkaline solution (40% NaOH solution, 80-90℃), reducing maintenance costs.

[0034] In this embodiment, both the double-layer water-cooled metal cover 3 and the double-layer water-cooled metal base plate 5 are made of stainless steel to ensure their reliability and durability as a cooling system.

[0035] To ensure the structural strength of the insulation cover assembly, reinforcing ribs 10 are provided on the inner and / or outer walls of the insulation cover assembly. The structural design of the reinforcing ribs 10 extends the service life of the insulation cover assembly to more than twice that of the unreinforced structure.

[0036] Specifically, in this embodiment, the inner cover 1 and the outer cover 2 are first assembled by fitting together, and then connected by screws, thus ensuring the stability of the assembled structure. The screws are made of high-temperature resistant ceramic matrix composites or ceramic materials such as carbon-carbon or carbon-ceramic. In practice, the port of the inner cover 1 is provided with a raised ring, and the port of the outer cover 2 abuts against the raised ring, and then is tightened using screws. Furthermore, the double-layer water-cooled metal cover 3 is also provided with a raised ring, and the two raised rings can be connected by screws after they are fitted together.

[0037] In this embodiment, the heat insulation cover assembly and the double-layer water-cooled metal cover 3 are connected by a snap ring structure. Specifically, a T-shaped ring 11 is provided on the outer wall of the heat insulation cover assembly, and a snap groove is formed between the T-shaped ring 11 and the outer wall of the heat insulation cover assembly. An L-shaped ring 12 is provided on the inner wall of the double-layer water-cooled metal cover 3, and the L-shaped ring 12 is snapped into the snap groove, thereby realizing a detachable connection between the heat insulation cover assembly and the double-layer water-cooled metal cover 3.

[0038] To improve the heat preservation effect, carbon-ceramic composite material tubes 9 are installed at the air inlet, air outlet, and electrode 6 mounting port. The air inlet pipe 7, air outlet pipe 8, and electrode 6 are installed inside the carbon-ceramic composite material tubes 9. Alternatively, high-purity high-temperature resistant ceramic tubes can be installed at the air inlet, air outlet, and electrode mounting port.

[0039] In this embodiment, water is used as the cooling medium in the double-layer water-cooled metal cover 3 and the double-layer water-cooled metal base plate 5. Of course, other liquids such as oil can also be used as the cooling medium.

[0040] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A silicon growth furnace with a heat insulation cover, comprising: The furnace bottom assembly, the heat insulation cover assembly, and the gas circulation system are characterized in that: the heat insulation cover assembly is covered on the furnace bottom assembly, and the furnace bottom assembly is provided with an air inlet, an air outlet, and an electrode mounting port; the heat insulation cover assembly includes an inner cover (1) and an outer cover (2), the inner cover (1) is made of high temperature resistant non-metallic material, the outer cover (2) is made of heat insulation material, and the outer side of the heat insulation cover assembly is also covered with a double-layer water-cooled metal cover (3); the furnace bottom assembly includes a double-layer water-cooled metal base plate (5) and a high temperature resistant non-metallic material base sleeve (4).

2. The silicon growth furnace with a heat insulation cover as described in claim 1, characterized in that: Both the high-temperature resistant non-metallic material component and the high-temperature resistant non-metallic material base sleeve (4) are made of carbon ceramic composite material.

3. The silicon growth furnace with a heat insulation cover as described in claim 1, characterized in that: The heat insulation cover assembly is detachably connected to the double-layer water-cooled metal cover (3).

4. The silicon growth furnace with a heat insulation cover as described in claim 2, characterized in that: Both the double-layer water-cooled metal cover (3) and the double-layer water-cooled metal base plate (5) are made of stainless steel.

5. The silicon growth furnace with a heat insulation cover as described in any one of claims 1-4, characterized in that: The insulation material component is a carbon fiber insulation material component, a silicon carbide insulation material component, or a silicon nitride fiber insulation material component.

6. The silicon growth furnace with a heat insulation cover as described in claim 5, characterized in that: The inner and / or outer walls of the heat insulation cover assembly are provided with reinforcing ribs (10).

7. The silicon growth furnace with a heat insulation cover as described in claim 6, characterized in that: The inner cover (1) and the outer cover (2) are connected by screws.

8. The silicon growth furnace with a heat insulation cover as described in claim 3, characterized in that: The heat insulation cover assembly and the double-layer water-cooled metal cover (3) are connected by a snap ring structure.

9. The silicon growth furnace with a heat insulation cover as described in claim 5, characterized in that: Carbon ceramic composite tubes (9) are installed at the air inlet, air outlet and electrode (6) mounting port.

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