Energy-saving polycrystalline silicon reduction furnace bell jar

Abstract

The utility model discloses an energy -saving polycrystal silicon reduction furnace bell jar, including reduction furnace bell jar, it is jacketed structure, is equipped with inner heat -insulating bushing in the inner wall of reduction furnace bell jar, and the inner heat -insulating bushing will be separated to form the preheating chamber to the inside of reduction furnace bell jar and the inner wall side close to it, and the bottom of inner heat -insulating bushing is equipped with material inlet, and the top is equipped with material outlet, and the material is sent into the inner heat -insulating bushing and is preheated and is sprayed into the reduction furnace bell jar from the material outlet of top prearranged position.

Description

Technical Field

[0001] This utility model relates to the technical field of polysilicon production equipment, specifically to an energy-saving polysilicon reduction furnace bell jar. Background Technology

[0002] The new energy consumption standards for polysilicon production are divided into three levels: Level 1, Level 2, and Level 3, with corresponding comprehensive energy consumption requirements of ≤5, 6, and 7.5 kWh / kg-Si, respectively (approximately 41, 49, and 61 kWh / kg-Si). Currently, the energy consumption of domestic silicon material manufacturers using the modified Siemens process is generally between 47 and 55 kWh / kg-Si, far from the Level 1 energy consumption standard. The power consumption of polysilicon production using the improved Siemens process can be mainly divided into two categories: reduction power consumption and power consumption. Reduction power consumption is between 36 and 42 kWh / kg-si, while power consumption is between 8 and 13 kWh / kg-si. Clearly, reduction power consumption accounts for about 80% of the total power consumption. Therefore, reducing reduction power consumption is of paramount importance if the overall power consumption of polysilicon production needs to be reduced.

[0003] The reduction reaction process involves introducing a mixture of chlorosilane gas and H2 (at around 150°C) into a reduction furnace to produce a vapor-phase deposition reaction. The reaction temperature of the silicon rod is approximately 1100°C, and the temperature of the exhaust gas is approximately 700-800°C. All the heat in the production process comes from electric heating. The heat required for the reduction chemical reaction accounts for approximately 5%, the heat carried away by the exhaust gas accounts for approximately 25%, and the heat carried away by the cooling water (chassis, electrodes, bell jar) accounts for approximately 70%. Therefore, if measures are taken to reduce the heat carried away by the cooling water, the power consumption of the reduction process can be reduced.

[0004] For the reasons mentioned above, it is necessary to propose an energy-saving polycrystalline silicon reduction furnace bell jar to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to overcome the defects in the existing technology and provide an energy-saving polycrystalline silicon reduction furnace bell jar.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows: An energy-saving polycrystalline silicon reduction furnace bell jar includes a reduction furnace bell jar with a jacketed structure. The lower part of the reduction furnace bell jar is provided with a bell jar cooling water inlet, and the top part is provided with a bell jar cooling water outlet. The bell jar cooling water enters the water jacket of the reduction furnace bell jar from the bottom bell jar cooling water inlet, and flows out from the top bell jar cooling water outlet after it is full, forming a circulation. An inner heat insulation liner is provided on the inner wall of the reduction furnace bell jar. The inner heat insulation liner divides the inside of the reduction furnace bell jar into a preheating chamber close to its inner wall. The bottom of the inner heat insulation liner is provided with a material inlet and the top is provided with a material outlet. The material is sent into the inner heat insulation liner, preheated, and then sprayed into the reduction furnace bell jar from the material outlet at the preset position at the top.

[0007] Furthermore, the inner heat insulation liner includes a cylindrical wall and a spiral flow guiding reinforcing ring. The diameter of the cylindrical wall is slightly smaller than that of the inner wall of the reduction furnace bell jar, so that an annular preheating cavity is formed between the cylindrical wall and the inner wall of the reduction furnace bell jar. The upper and lower ends of the preheating cavity are sealed to the reduction furnace bell jar. The spiral flow guiding reinforcing ring is arranged in a coaxial spiral ring in the preheating cavity, so that a spiral upward flow channel is formed in the preheating cavity.

[0008] Furthermore, the material inlet includes a ring of cold material intake buffer chambers set at the bottom of the preheating chamber, and a feeding pipe is provided through the bottom of the reduction furnace bell and connected to the intake buffer chambers; multiple feeding nozzles are provided through the side wall of the intake buffer chambers.

[0009] Furthermore, several of the aforementioned feeding nozzles are disposed on the inner ring sidewall and top sidewall of the cold material inlet buffer cavity, and are evenly distributed around the circumference of the reduction furnace bell jar.

[0010] Furthermore, the material spray outlet is disposed through the upper side wall of the inner heat insulation liner, the opening of the material spray outlet points towards the inside of the reduction furnace bell jar, and several material spray outlets are evenly distributed in the circumferential direction.

[0011] Furthermore, the inner heat insulation liner and the reduction furnace bell are detachably installed, and fastening screws are provided at the bottom of the inner heat insulation liner to connect the inner heat insulation liner and the reduction furnace bell into a whole.

[0012] Furthermore, the assembly gap between the spiral flow guiding reinforcing ring and the bell jar of the reduction furnace should be ≤1mm.

[0013] Furthermore, the distance between the inner wall of the inner insulation liner and the outermost silicon rod is ≥300mm.

[0014] Furthermore, the polishing precision of the inner wall of the inner heat insulation liner is Ra0.05~0.2.

[0015] The advantages and beneficial effects of this invention are as follows: This structure utilizes an inner heat-insulating liner and a preheating cavity between the inner heat-insulating liner and the bell jar of the reduction furnace to form two heat-insulating layers, thereby reducing the heat carried away by the cooling water of the bell jar. Simultaneously, the material entering the preheating cavity is preheated through the jacket before entering the reaction chamber from the top, which improves the gas field and material distribution at the top of the reduction furnace, increasing the proportion and growth rate of dense material at the top. Under these optimized conditions, the reduction power consumption can be significantly reduced. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an energy-saving polycrystalline silicon reduction furnace bell jar according to this utility model; Figure 2 This is a utility model Figure 1 Enlarged schematic diagram of point I in the middle; Figure 3 This is a utility model Figure 1 Enlarged schematic diagram at point II; In the diagram: 1. Reduction furnace bell jar; 2. Inner heat insulation liner; 3. Spiral guide reinforcing ring; 4. Cold material inlet buffer chamber; 5. Bell jar cooling water inlet; 6. Bell jar cooling water outlet; 7. Fastening screw; 8. Material spray outlet; 9. Feeding pipe; 10. Feeding nozzle; 11. Silicon rod. Detailed Implementation

[0017] The specific embodiments of this utility model will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0018] An electrode insulation structure for a polycrystalline silicon reduction furnace, such as Figure 1-3 As shown, it includes a reduction furnace bell jar 1, an inner heat insulation liner 2, a spiral flow guiding reinforcing ring 3, a cold material inlet buffer chamber 4, a bell jar cooling water inlet 5, a bell jar cooling water outlet 6, and fastening screws 7. The bell jar 1 of the reduction furnace is provided with a bell jar cooling water inlet 5 at the bottom and a bell jar cooling water outlet 6 at the top. The bell jar cooling water enters the bell jar 1 of the reduction furnace from the bottom bell jar cooling water inlet 5, and after it is full, it comes out from the top bell jar cooling water outlet 6, forming a circulation. The inner heat insulation liner 2 is welded with a spiral flow guiding ring 3 on the outside. The spiral flow guiding ring 3 can improve the rigidity of the inner heat insulation liner 2 on the one hand, and guide the cold material on the other hand, thus enhancing the cooling effect. A fastening screw 7 is provided at the bottom of the inner heat insulation liner 2. The inner heat insulation liner 2 and the reduction furnace bell jar 1 are connected into a whole by the fastening screw 7, which is convenient for hoisting and use. A material spray outlet 8 is provided at the top of the inner heat insulation liner 2. The cold material inlet buffer chamber 4 is located at the bottom of the bell jar 1 of the reduction furnace, and the top and sides of the cold material inlet buffer chamber 4 are provided with feeding nozzles 10.

[0019] Furthermore, the spiral flow guiding reinforcing ring 3 needs to be assembled with the reduction furnace bell jar 1 with a controlled gap to prevent cold materials from short-circuiting within the gap. It is recommended that the gap be controlled to ≤1mm.

[0020] Furthermore, the inner cylinder of the inner heat insulation liner 2 needs to be polished to enhance surface emission and reduce heat radiation. A polishing precision of Ra 0.05~0.2 is recommended.

[0021] Furthermore, the height of the inner cylinder of the inner insulation liner 2 is slightly higher than that of the silicon rod 11.

[0022] Furthermore, it is recommended that the distance between the inner wall of the inner heat insulation liner 2 and the outermost silicon rod 11 be ≥300mm.

[0023] Furthermore, it is recommended that the inner cylinder of the inner insulation liner 2 be made of high-temperature resistant stainless steel or high-temperature resistant nickel-based alloy.

[0024] Furthermore, the top of the inner cylinder of the inner insulation liner 2 is provided with a material spray outlet 8. It is recommended that the material spray outlet 8 be arranged in 2 to 3 rows with a nozzle diameter of 3 to 5 mm and evenly distributed in the circumferential direction.

[0025] Furthermore, the top and lower sides of the cold material inlet buffer cavity 4 are provided with feeding nozzles 10, with a recommended nozzle diameter of 3~5mm, evenly distributed, and the total flow area of ​​the feeding nozzles 10 is equivalent to the total area of ​​the material outlet 8 at the top of the inner cylinder of the inner heat insulation liner 2.

[0026] Furthermore, the inner heat insulation liner 2 needs to be connected to the reduction furnace bell jar 1 by a movable connection structure, such as bolt fastening, and should be cleaned after each furnace is used.

[0027] Furthermore, it is recommended that the cold material be a mixture of chlorosilane and H2 gas. After preheating, the mixture gas enters the reaction chamber inside the bell jar 1 of the reduction furnace from the top, which can improve the gas field and material distribution at the top of the reduction furnace.

[0028] Furthermore, the cold material inlet buffer chamber 4 needs to be separated from the reduction furnace feeding system. When the early thermal zone temperature is low, no material is fed into the cold material inlet buffer chamber 4. The cold material is then fed in after the temperature inside the reduction furnace rises.

[0029] Combined with appendix Figure 1-3 As can be seen, this utility model comprises a reduction furnace bell jar 1, an inner heat-insulating liner 2, a spiral flow-guiding reinforcing ring 3, a cold material inlet buffer chamber 4, a bell jar cooling water inlet 5, a bell jar cooling water outlet 6, and fastening screws 7. The inner heat-insulating liner 2 is installed inside the reduction furnace bell jar 1 by fastening screws 7. When the furnace temperature rises, a mixture of chlorosilane and H2 in a specific ratio is introduced into the cold material inlet buffer chamber 4. The cold material inlet buffer chamber 4 has material spray outlets 8 at its top and bottom. The low-temperature mixed gas enters the cavity between the reduction furnace bell jar 1 and the inner heat-insulating liner 2 through the feeding nozzle 10, flows upward along the spiral flow-guiding reinforcing ring 3 in the cavity, and absorbs heat from the inner heat-insulating liner 2 during this process. The heat-absorbing material enters the reaction chamber from the material spray outlet at the top of the inner heat-insulating liner 2 to participate in the reduction reaction.

[0030] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. An energy-saving bell jar for a polycrystalline silicon reduction furnace, characterized in that, The bell jar of the reduction furnace is a jacketed structure. The bell jar has a cooling water inlet at the bottom and a cooling water outlet at the top. The cooling water enters the water jacket of the bell jar from the bottom cooling water inlet and flows out from the top cooling water outlet after it is full, forming a circulation. An inner heat insulation liner is provided on the inner wall of the reduction furnace bell jar. The inner heat insulation liner divides the inside of the reduction furnace bell jar into a preheating chamber close to its inner wall. The bottom of the inner heat insulation liner is provided with a material inlet and the top is provided with a material outlet. The material is sent into the inner heat insulation liner, preheated, and then sprayed into the reduction furnace bell jar from the material outlet at the preset position at the top.

2. The energy-saving polycrystalline silicon reduction furnace bell jar according to claim 1, characterized in that, The inner heat insulation liner includes a cylindrical wall and a spiral flow guiding reinforcing ring. The diameter of the cylindrical wall is slightly smaller than that of the inner wall of the reduction furnace bell jar, so that a ring-shaped preheating cavity is formed between the cylindrical wall and the inner wall of the reduction furnace bell jar. The upper and lower ends of the preheating cavity are sealed to the reduction furnace bell jar. The spiral flow guiding reinforcing ring is arranged in a coaxial spiral ring in the preheating cavity, so that a spiral upward flow channel is formed in the preheating cavity.

3. The energy-saving polycrystalline silicon reduction furnace bell jar according to claim 1, characterized in that, The material inlet includes a ring of cold material intake buffer chambers set at the bottom of the preheating chamber, and a feeding pipe is provided through the bottom of the reduction furnace bell and connected to the intake buffer chambers; multiple feeding nozzles are provided through the side wall of the intake buffer chambers.

4. The energy-saving polycrystalline silicon reduction furnace bell jar according to claim 3, characterized in that, Several of the aforementioned feeding nozzles are disposed on the inner ring sidewall and top sidewall of the cold material inlet buffer cavity, and are evenly distributed around the circumference of the reduction furnace bell jar.

5. The energy-saving polycrystalline silicon reduction furnace bell jar according to claim 1, characterized in that, The material ejector is installed through the upper side wall of the inner heat insulation liner, and the opening of the material ejector points towards the inside of the reduction furnace bell jar. Several material ejectors are evenly distributed in the circumferential direction.

6. The energy-saving polycrystalline silicon reduction furnace bell jar according to any one of claims 2-5, characterized in that, The inner heat insulation liner and the reduction furnace bell are detachably installed. Fastening screws are provided at the bottom of the inner heat insulation liner, and the inner heat insulation liner and the reduction furnace bell are connected into a whole by the fastening screws.

7. The energy-saving polycrystalline silicon reduction furnace bell jar according to claim 2, characterized in that, The assembly gap between the spiral flow guiding reinforcing ring and the bell jar of the reduction furnace should be ≤1mm.

8. The energy-saving polycrystalline silicon reduction furnace bell jar according to claim 1, characterized in that, The distance between the inner wall of the inner insulation liner and the outermost silicon rod is ≥300mm.

9. The energy-saving polycrystalline silicon reduction furnace bell jar according to claim 1, characterized in that, The polishing precision of the inner wall of the inner heat insulation liner is Ra0.05~0.2.

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