Feeding system of reduction furnace

Abstract

The utility model relates to the technical field of polycrystalline silicon production, in particular to a feeding system of a reduction furnace, which is characterized in that a material inlet of an evaporator is used for inputting materials to be added; the superheater is communicated with the evaporator; a material inlet I of the mixer is communicated with the superheater; a material inlet of the heat exchanger I communicates with a material outlet of the mixer; a material inlet of the second heat exchanger communicates with a material outlet of the first heat exchanger. A medium inlet of the heat exchanger II is communicated with an exhaust port of the reduction furnace; a material outlet of the heat exchanger II is communicated with a gas inlet of the reduction furnace; a material inlet of the heat exchanger III is used for inputting nitrogen; a material outlet of the heat exchanger III is communicated with a gas inlet of the reduction furnace; a communicating pipe is arranged between the material inlet of the heat exchanger III and the material outlet of the heat exchanger III; and a medium inlet of the heat exchanger III is used for inputting a refrigerant medium. The cooling device can improve the cooling speed of the silicon rod in the reduction furnace, reduce metal on the surface of the silicon rod, improve the quality of the silicon rod and reduce nitrogen consumption at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon production, in particular to a reduction furnace feeding system. Background Art

[0002] High-purity polysilicon is the main material for solar cell manufacturing. At present, the Siemens improved process is mainly used in the domestic production of high-purity polysilicon. The process principle is to introduce high-purity trichlorosilane and hydrogen into the reduction furnace in a certain ratio, and a reduction reaction occurs at 1080℃~1200℃ and 6bar to generate high-purity polysilicon, while producing by-products such as hydrogen chloride, silicon tetrachloride and dichlorodihydrogen silicon. After the growth time is reached, the silicon rods of a single furnace are disassembled after power failure, reduction, replacement cooling, and then sent for crushing and packaging. The feeding method of the reduction furnace is: the concentrated vaporized trichlorosilane is mixed with hydrogen and sprayed into the reduction furnace for reaction; after the furnace is shut down and the power is cut off, the reduction furnace is first replaced with hot hydrogen to reduce the chlorosilane content in the reduction furnace, and then nitrogen at room temperature is introduced to replace the chlorosilane and hydrogen in the reduction furnace, and the sample is disassembled after passing the sampling. In actual production, a large amount of nitrogen is consumed in the process of replacing chlorosilane and hydrogen and cooling silicon rods. After the replacement is qualified and the furnace is dismantled, the surface temperature of the silicon rod can still reach 120-250°C. The silicon rod needs to be exposed to the air to continue cooling down to meet the disassembly conditions. When the silicon rod is exposed to the air for a long time, the surface will accelerate the adsorption of impurity ions due to the high temperature, resulting in an increase in the surface metal and affecting the quality of the silicon rod. Utility Model Content

[0003] In view of this, the utility model provides a reduction furnace feeding system, the main purpose of which is to increase the cooling rate of silicon rods in the reduction furnace, reduce the surface metal of the silicon rods, improve the quality of the silicon rods, and reduce nitrogen consumption.

[0004] In order to achieve the above purpose, the utility model mainly provides the following technical solutions:

[0005] The embodiment of the utility model provides a reduction furnace feeding system, comprising: an evaporator, a superheater, a mixer, a heat exchanger 1, a heat exchanger 2, a heat exchanger 3 and a reduction furnace;

[0006] The material inlet of the evaporator is used for inputting materials to be added to the reduction furnace;

[0007] The material inlet of the superheater is connected to the material outlet of the evaporator;

[0008] The material inlet 1 of the mixer is connected to the material outlet of the superheater; the material inlet 2 of the mixer is used for hydrogen input;

[0009] The material inlet of the heat exchanger 1 is connected to the material outlet of the mixer;

[0010] The material inlet of the heat exchanger 2 is connected to the material outlet of the heat exchanger 1;

[0011] The medium inlet of the second heat exchanger is communicated with the exhaust port of the reduction furnace; the medium outlet of the second heat exchanger is communicated with the tail gas treatment system;

[0012] The material outlet of the second heat exchanger is connected to the air inlet of the reduction furnace;

[0013] The material inlet of the heat exchanger 3 is used for nitrogen input; the material outlet of the heat exchanger 3 is connected to the air inlet of the reduction furnace;

[0014] A connecting pipe is provided between the material inlet of the heat exchanger 3 and the material outlet of the heat exchanger 3; a control valve is provided on the connecting pipe;

[0015] The medium inlet of the heat exchanger three is used for inputting the cold medium.

[0016] Further, it also includes: a heat exchanger four;

[0017] The material inlet of the heat exchanger four is connected to the exhaust port of the reduction furnace; the material outlet of the heat exchanger four is connected to the medium inlet of the heat exchanger two.

[0018] Furthermore, the heat exchanger four is a jacketed heat exchanger.

[0019] Furthermore, there are at least two heat exchangers four; and at least two heat exchangers four are arranged in series.

[0020] Furthermore, the tail gas treatment system is a tail gas separation and purification system.

[0021] By means of the above technical solution, the reduction furnace feeding system of the utility model has at least the following advantages:

[0022] It can increase the cooling rate of silicon rods in the reduction furnace, reduce the surface metal of silicon rods, improve the quality of silicon rods, and reduce nitrogen consumption.

[0023] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the utility model in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a reduction furnace feeding system provided in an embodiment of the utility model.

[0025] As shown in the figure:

[0026] 1 is an evaporator, 2 is a superheater, 3 is a heat exchanger 1, 4 is a heat exchanger 2, 5 is a heat exchanger 3, 6 is a reduction furnace, 7 is a heat exchanger 4, 8 is a mixer, and 9 is a connecting pipe. DETAILED DESCRIPTION

[0027] In order to further explain the technical means and effects adopted by the utility model to achieve the predetermined utility model purpose, the specific implementation methods, structures, features and effects of the utility model application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0028] like Figure 1 As shown, a reduction furnace feeding system proposed in an embodiment of the utility model includes: an evaporator 1, a superheater 2, a mixer 8, a heat exchanger 3, a heat exchanger 2 4, a heat exchanger 3 5 and a reduction furnace 6; the material inlet of the evaporator 1 is used for the input of materials to be added to the reduction furnace 6; the material inlet of the superheater 2 is connected to the material outlet of the evaporator 1; the material inlet 1 of the mixer 8 is connected to the material outlet of the superheater 2; the material inlet 2 of the mixer 8 is used for hydrogen input; the material inlet of the heat exchanger 3 is connected to the material outlet of the mixer 8; the material inlet of the heat exchanger 2 4 is connected to the material outlet of the heat exchanger 3; the medium inlet of the heat exchanger 2 4 is connected to the exhaust port of the reduction furnace 6; the medium outlet of the heat exchanger 2 4 is connected to the exhaust gas treatment system; preferably, the exhaust gas treatment system is an exhaust gas separation and purification system, so that the exhaust gas can be separated and purified and then continued to be used. The material outlet of heat exchanger 2 4 is connected to the air inlet of reduction furnace 6, so that the material heated by heat exchanger 2 4 can be passed into reduction furnace 6; the material inlet of heat exchanger 3 5 is used for nitrogen input; the material outlet of heat exchanger 3 5 is connected to the air inlet of reduction furnace 6; the medium inlet of heat exchanger 3 5 is used for the input of cold medium. The cold medium exchanges heat with nitrogen through heat exchanger 3 5, so that the temperature of nitrogen entering reduction furnace 6 is reduced, which can accelerate the cooling of silicon rods. There is a connecting pipe 9 between the material inlet of heat exchanger 3 5 and the material outlet of heat exchanger 3 5; a control valve is arranged on the connecting pipe 9; so that heat exchanger 3 5 can be put into use and cut out at any time according to different replacement stages and different seasons.

[0029] After the reduction furnace 6 is started, trichlorosilane is heated by the evaporator 1, enters the superheater 2 to be further heated by medium-pressure steam, then mixed with hydrogen, and then heated by the heat exchanger 1 3. After secondary heat exchange with the tail gas from the reduction furnace 6 through the heat exchanger 2 4, it enters the reduction furnace 6 for reaction. The tail gases such as chlorosilane and hydrogen produced by the reaction pass through the heat exchanger 4 7, are heat exchanged and cooled by cooling water, and then pass through the heat exchanger 2 4 to the subsequent section for separation and purification; after the reduction furnace 6 completes a growth cycle, after power off, reduction, and hydrogen replacement, nitrogen is cooled by the refrigerant through the heat exchanger 3 5, and then enters the reduction furnace 6 to cool the silicon rods and replace the gas; after the replacement is qualified and the furnace is dismantled, the silicon rods can be directly disassembled without being exposed to the air for cooling, thereby effectively reducing the accumulation of metal impurities on the surface of the silicon material, reducing the surface metal content, and improving the quality of the silicon material.

[0030] A reduction furnace feeding system proposed in an embodiment of the utility model can increase the cooling speed of silicon rods in the reduction furnace 6, reduce the exposure time of silicon materials in the air after the furnace is dismantled, reduce the metal content on the surface of the silicon rods, and improve the quality of the silicon rods. At the same time, it can reduce nitrogen consumption, reduce the nitrogen introduction time, and improve the replacement and cooling efficiency.

[0031] As a preference of the above-mentioned embodiments, a reduction furnace feeding system proposed in one embodiment of the utility model further includes: a heat exchanger 47; the material inlet of the heat exchanger 47 is connected to the exhaust port of the reduction furnace 6 to cool the gas discharged from the reduction furnace 6; the material outlet of the heat exchanger 47 is connected to the medium inlet of the heat exchanger 24 to heat the material passing through the heat exchanger 24 by the waste heat of the gas discharged from the reduction furnace 6. Further preferably, the heat exchanger 47 is a jacketed heat exchanger to perform heat exchange while ensuring the fluidity of the material. Further preferably, there are at least two heat exchangers 47; at least two heat exchangers 47 are arranged in series to further reduce the temperature of the gas discharged from the reduction furnace 6.

[0032] Research shows that as the silicon material is placed for a longer time, the amount of metal impurities accumulated on the surface of the silicon material continues to increase. After the furnace is dismantled, the silicon material is sampled at different cooling time periods, and some index data of the surface metal are tested, as shown in the following table:

[0033] Fe Mg Cu Zn Al K Na Ca Remark Group 2 0.64 0.05 0.02 0.10 0.14 0.07 0.69 0.30 2H after unpacking Group 1 0.02 0.00 0.00 0.01 0.11 0.03 0.03 0.02 0.5H after disassembly

[0034] Further explanation, although the terms first, second, etc. can be used to describe various elements in this article, these terms should not limit these elements. These terms are only used to distinguish one element from another element. For example, the first element can be called the second element, and, similarly, the second element can be called the first element, and these terms are only used to distinguish one element from another element. This does not depart from the scope of exemplary embodiments. Similarly, element one and element two do not represent the order of elements, and these terms are only used to distinguish one element from another element. As used herein, the term "and / or" includes any combination and all combinations of one or more associated listed items.

[0035] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] The standard parts used in the utility model can all be purchased from the market, and special-shaped parts can be customized according to the instructions and the drawings. The specific connection methods of each part adopt the conventional means such as mature bolts, rivets, welding, etc. in the existing technology. The machinery, parts and equipment all adopt the conventional models in the existing technology, and the circuit connection adopts the conventional connection method in the existing technology, which will not be described in detail here.

[0037] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A reduction furnace feeding system, characterized in that: Including: evaporator, superheater, mixer, heat exchanger 1, heat exchanger 2, heat exchanger 3 and reduction furnace; The material inlet of the evaporator is used for inputting materials to be added to the reduction furnace; The material inlet of the superheater is connected to the material outlet of the evaporator; The material inlet 1 of the mixer is connected to the material outlet of the superheater; the material inlet 2 of the mixer is used for hydrogen input; The material inlet of the heat exchanger 1 is connected to the material outlet of the mixer; The material inlet of the heat exchanger 2 is connected to the material outlet of the heat exchanger 1; The medium inlet of the second heat exchanger is communicated with the exhaust port of the reduction furnace; the medium outlet of the second heat exchanger is communicated with the tail gas treatment system; The material outlet of the second heat exchanger is connected to the air inlet of the reduction furnace; The material inlet of the heat exchanger 3 is used for nitrogen input; the material outlet of the heat exchanger 3 is connected to the air inlet of the reduction furnace; A connecting pipe is provided between the material inlet of the heat exchanger 3 and the material outlet of the heat exchanger 3; a control valve is provided on the connecting pipe; The medium inlet of the heat exchanger three is used for inputting the cold medium.

2. The reduction furnace feeding system according to claim 1, characterized in that: Also included: heat exchanger four; The material inlet of the heat exchanger four is connected to the exhaust port of the reduction furnace; the material outlet of the heat exchanger four is connected to the medium inlet of the heat exchanger two.

3. The reduction furnace feeding system according to claim 2, characterized in that: The heat exchanger four is a jacketed heat exchanger.

4. The reduction furnace feeding system according to claim 3, characterized in that: There are at least two heat exchangers four; at least two heat exchangers four are arranged in series.

5. The reduction furnace feeding system according to claim 1, characterized in that: The tail gas treatment system is a tail gas separation and purification system.

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