Polycrystalline silicon preparation device

Abstract

The utility model provides a preparation device of polycrystalline silicon, and aims to solve the technical problems that the traditional improved Siemens method for preparing the polycrystalline silicon is often accompanied by side reaction, the reaction efficiency is low, and the yield of the polycrystalline silicon is not high. The device comprises a plasma reaction unit and a raw material pretreatment unit. The plasma reaction unit is sequentially divided into a reaction cylinder and a forming cylinder from top to bottom. And the reaction cylinder is provided with a multi-stage feeding end below the plasma generator. And a homogenizer arranged in the reaction cylinder divides the multi-stage feeding end into an upper feeding end and a lower feeding end. And each feeding end is provided with a nozzle group which is arranged in the circumferential direction of the cross section of the reaction cylinder and is used for spraying silicon raw materials at multiple angles. The forming cylinder is used for cooling forming of silicon liquid drops, and a discharging valve is arranged at the discharging end of the forming cylinder. An atomizer of the raw material pretreatment unit is connected with the feeding end of the reaction cylinder through a discharging pipeline. While the silicon liquid drops are formed by feeding at the lower feeding end, the silicon liquid drops formed by feeding at the upper feeding end disturb the silicon liquid drops in the reaction chamber, so that the yield of polycrystalline silicon grains is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparing polycrystalline silicon by plasma method, and particularly relates to a polycrystalline silicon preparation device. BACKGROUND

[0002] Polycrystalline silicon is a basic raw material for the photovoltaic industry, and the demand for polycrystalline silicon is increasing year by year. At present, there are two major schools for preparing polycrystalline silicon, namely, the modified Siemens method and the silane fluidized bed method. Among them, the modified Siemens method is currently the mainstream method in the industry, which mainly uses hydrogen to reduce silicon tetrachloride on a silicon core (seed crystal) to produce by chemical vapor deposition. It is found by the technical personnel that this method is accompanied by a large number of side reactions to generate silicon tetrachloride, dichlorodisilane and other chlorosilanes, which slow down the reaction rate and reduce the yield of polycrystalline silicon products. Moreover, the use of a reduction furnace for deposition on a silicon core will gradually reduce the surface temperature of the silicon rod as the size of the silicon rod increases, which will also reduce the reaction rate, thereby greatly prolonging the production cycle.

[0003] In order to overcome the shortcomings of the Siemens process, an invention patent with the application number CN201711213856.7 discloses a method for converting silicon tetrachloride into SiHCl3 and polycrystalline silicon. Hydrogen or a mixture of hydrogen and argon is used as the plasma working gas, which is sent into a plasma generator to form a hot plasma jet with a temperature of 4000K or above under the action of a strong electric field. The SiCl4 in the reactor is induced to undergo a reduction reaction to convert SiCl4 into SiHCl3 and polycrystalline silicon, thereby shortening the production cycle and improving the conversion rate of silicon tetrachloride. The yield of polycrystalline silicon can reach 25%~45%. CONTENT OF THE UTILITY MODEL

[0004] The utility model provides a kind of preparation device of polycrystalline silicon to solve the problems raised in the above background technology.

[0005] A kind of preparation device of polycrystalline silicon, it includes:

[0006] Plasma reaction unit is divided into reaction cylinder and forming cylinder from top to bottom direction in sequence;

[0007] The reaction cylinder is provided with multiple-stage feeding end below the plasma generator;The homogenizer is installed in the reaction cylinder, and the homogenizer separates the multiple-stage feeding end into upper feeding end and lower feeding end;Each feeding end is provided with nozzle group arranged around the cross section of the reaction cylinder for multi-angle injection of silicon raw material;

[0008] The forming cylinder is used for cooling and forming of silicon droplets, and the discharge valve is arranged at the discharge end of the forming cylinder;

[0009] The raw material pretreatment unit is connected with the feeding end of the reaction cylinder through the discharge pipeline of the atomizer.

[0010] Further, the nozzle group is installed in the reaction cylinder in two ways: the nozzle group is installed in the reaction cylinder through a first connecting pipe surrounding the outer wall of the reaction cylinder, for spraying the silicon raw material into the reaction cylinder from the outside to the inside of the reaction cylinder; or the nozzle group is installed in the reaction cylinder through a second connecting pipe, for spraying the silicon raw material into the reaction chamber from the inside to the outside of the reaction cylinder.

[0011] Further, the multi-stage feeding end is installed with any one of the nozzle groups or a combination of the two nozzle groups.

[0012] Further, the first connecting pipe comprises a first annular pipe and a plurality of shunt pipes;

[0013] The first annular pipe is connected with the discharge pipe on the outer wall, and surrounds the outer wall of the reaction cylinder.

[0014] The plurality of shunt pipes are connected with the first annular pipe on the inner wall in the circumferential direction, and the other end penetrates the reaction cylinder and is installed with a nozzle.

[0015] Further, the second connecting pipe comprises a second annular pipe, a mounting pipe and a fixing pipe; the second annular pipe is installed in the reaction cylinder; the nozzles are installed on the outer wall of the second annular pipe in the circumferential direction; the second annular pipe is connected with the fixing pipe through the mounting pipe; and the fixing pipe is connected with the discharge pipe.

[0016] Further, the nozzle adopts an elbow structure; one end of the mounting pipe is connected with the second annular pipe, and the other end is rotatably connected with the fixing pipe, for rotating the nozzle group around the axis of the reaction cylinder.

[0017] Further, the mounting pipe is composed of a main pipe and a plurality of branch pipes; one end of the plurality of branch pipes is connected with the inner wall of the second annular pipe in the circumferential direction, and the other end extends to the center of the second annular pipe and is connected with one end of the main pipe.

[0018] The fixing pipe is composed of a vertical pipe part and a horizontal pipe part; one end of the vertical pipe part is rotatably connected with the other end of the main pipe, and the other end is connected with one end of the horizontal pipe part, and the other end of the horizontal pipe part penetrates the side wall of the reaction cylinder and extends outward to be connected with the discharge pipe.

[0019] Further, the upper feeding end is installed with the nozzle group installed in the reaction cylinder through the second connecting pipe.

[0020] Further, the reaction cylinder and the forming cylinder are connected up and down through a buffer cylinder; the buffer cylinder is installed with a material blocking valve for controlling the intercommunication or plugging between the inner chambers of the reaction cylinder and the forming cylinder; the buffer cylinder is also installed with a charging and exhausting device, which is arranged below the material blocking valve; the gas replacement in the forming cylinder is realized through the cooperation of the material blocking valve and the material blocking valve.

[0021] Further, the homogenizer is composed of one or more layers of porous plates.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] (1) The silicon liquid drops formed by the feeding at the lower feeding end disturb the silicon liquid drops in the reaction chamber while the silicon liquid drops formed by the feeding at the upper feeding end, which is beneficial to improve the yield of polysilicon particles and improve the production efficiency.

[0024] (2) The plasma reaction performed by the device not only has wide applicability to raw materials, but also eliminates the process of pre-distillation and purification of materials in the traditional method, reduces the investment cost, and adopts a passive plasma device to control the metal and base metal impurities on the product surface.

[0025] (3) Compared with the traditional method of producing polysilicon by using the Siemens method or the silane fluidized bed method, the device has small volume and small floor area, and can avoid the use of crystal seeds. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0027] Figure 1 It is a front view schematic diagram of a polysilicon preparation device according to an embodiment of the present application.

[0028] Figure 2 It is a front view schematic diagram of a polysilicon preparation device according to an embodiment of the present application.

[0029] Figure 3 It is a top view schematic diagram of a nozzle structure of a polysilicon preparation device according to an embodiment of the present application, which sprays silicon raw materials from the outside of the cavity to the inside of the cavity.

[0030] Figure 4 It is a schematic diagram of a nozzle structure of a polysilicon preparation device according to an embodiment of the present application, which sprays silicon raw materials from the inside of the cavity to the outside of the cavity.

[0031] REFERENCE NUMERALS:

[0032] 1. Reaction cylinder; 10. Plasma generator; 120a. Upper feed end; 120b. Lower feed end; 121. First annular tube; 122. Split tube; 123. Nozzle; 124. Second annular tube; 130. Branch pipe; 131. Main pipe; 140. Vertical pipe portion; 141. Horizontal pipe portion; 15. Homogenizer; 16. Tail gas outlet;

[0033] 2. Buffer cylinder; 21. Material blocking valve;

[0034] 3. Forming cylinder; 31. Discharge valve; 32. Discharge end;

[0035] 4. Atomizer; 41. Discharge valve; 42. Discharge pipeline. DETAILED DESCRIPTION

[0036] Hereinafter, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0037] In the description of the present application, it needs to be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", "axial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the present application is used, or the orientation or positional relationship commonly understood by those skilled in the art, 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 indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0038] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features.

[0039] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the communication or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can include the first and second features directly contacting, or the first and second features not directly contacting but contacting through another feature between them. Moreover, the first feature "on", "above" and "on top of" the second feature includes the first feature directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "underneath" the second feature includes the first feature directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0041] The disclosure below 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. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0042] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0043] The present embodiment also provides a device for producing granular polysilicon by plasma method, please refer to Figures 1-4 which comprises a plasma reaction unit and a raw material pretreatment unit.

[0044] Specifically,

[0045] The plasma reaction unit is sequentially divided into a reaction cylinder 1, a buffer cylinder 2 and a forming cylinder 3 from top to bottom. A blocking valve 21 is installed on the buffer cylinder 2 to control the intercommunication or blockage between the inner chamber of the reaction cylinder (hereinafter collectively referred to as "reaction chamber") and the inner chamber of the forming cylinder (hereinafter collectively referred to as "forming chamber").

[0046] The reaction cylinder 1 is equipped with a plasma generator 10 for emitting a plasma energy beam. An initial plasma carrier gas is introduced into the reaction cylinder 1 for stabilizing the plasma reaction of the material. The reaction cylinder 1 is provided with an exhaust outlet 16 near its top end for facilitating the discharge of the exhaust gas generated after the plasma reaction of the silicon material. A homogenizer 15 is installed in the inner chamber of the reaction cylinder 1, which can be composed of one or more porous plates, and the homogenizer 15 is arranged below the plasma generator 10. Meanwhile, the feeding end of the reaction cylinder 1 is also located below the plasma generator 10. The feeding end is divided into an upper feeding end 120a and a lower feeding end 120b, and the homogenizer 15 is arranged between the upper feeding end 120a and the lower feeding end 120b. When the silicon material is simultaneously introduced into the reaction cylinder 1 from the upper feeding end 120a and the lower feeding end 120b, the silicon material introduced into the reaction chamber through the upper feeding end 120a and the silicon material dispersed by the homogenizer 15 through the lower feeding end 120b both undergo plasma reaction to form silicon droplets. The silicon droplets formed after the introduction through the upper feeding end 120a collide with the silicon droplets in the reaction chamber to form larger silicon droplets, which is beneficial to improve the yield of the polycrystalline silicon product.

[0047] Either the upper feeding end 120a or the lower feeding end 120b can be matched with a nozzle group for spraying the silicon material into the reaction chamber. The nozzle group can be arranged in the following two ways in the reaction cylinder 1: the nozzle group is installed in the reaction cylinder 1 through a first connecting pipe arranged around the outer wall of the reaction cylinder, so that the nozzles 123 realize the spraying of the silicon material from the outside of the chamber to the inside of the chamber into the reaction chamber; or the nozzle group is arranged along the circumferential direction of the cross section of the reaction cylinder 1 through a second connecting pipe arranged in the reaction cylinder, so that the silicon material is sprayed from the inside of the chamber to the outside of the chamber into the reaction chamber. When the nozzles 123 are installed at the upper feeding end 120a and the lower feeding end 120b, either of the above-mentioned nozzle group arrangement ways or both of the nozzle group arrangement ways can be used. Meanwhile, either the upper feeding end 120a or the lower feeding end 120b can be installed with multiple nozzle groups.

[0048] Preferably, the installation of the above-mentioned two nozzle groups in the reaction cylinder 1 is as follows: the installation of the nozzle group for spraying the silicon material from the outside of the chamber to the inside of the chamber is as follows: the first connecting pipe includes a first annular pipe 121 and a shunt pipe 122. The first annular pipe 121 is arranged around the outer wall of the reaction cylinder, and the inner wall thereof is connected with the shunt pipe 122 along the circumferential direction thereof. The shunt pipe 122 is installed through the upper feeding end 120a or the lower feeding end 120b of the reaction cylinder 1, and extends into the reaction chamber and is connected with the nozzles 123. Therefore, after the silicon material is introduced into the first annular pipe 121, it is shunted and transmitted to the corresponding nozzles 123 through the shunt pipe 122 for spraying.

[0049] The installation mode of the nozzle group spraying silicon raw materials from the cavity to the cavity is as follows: taking the center of the reaction chamber as the center, the nozzle group is arranged in the reaction chamber through the second connecting pipe, so that the silicon raw materials are sprayed from the center to the outside in the reaction chamber. The second connecting pipe includes a second annular pipe 124, a mounting pipe, and a fixed pipe. The nozzle 123 is mounted on the outer wall of the second annular pipe, the second annular pipe 124 is rotationally connected to one end of the fixed pipe through the mounting pipe, and the other end of the fixed pipe leads out of the reaction cylinder 1. The nozzle 123 adopts a bent pipe structure. Among them,

[0050] The nozzles 123 are installed on the second annular pipe 124 in a circumferential direction. The mounting pipe can be composed of a main pipe 131 and a plurality of branch pipes 130. Along the circumferential direction of the second annular pipe 124, the plurality of branch pipes 130 are connected to the inner wall of the second annular pipe at one end, and the other end extends to the center of the second annular pipe 124 and is connected to one end of the main pipe 131, and the other end of the main pipe 131 is rotationally connected to the fixed pipe.

[0051] The fixed pipe is composed of a vertical pipe part 140 and a horizontal pipe part 141. One end of the vertical pipe part 140 is connected to the main pipe 131, and the other end is connected to one end of the horizontal pipe part 141. The other end of the horizontal pipe part 141 extends outwards through the side wall of the reaction cylinder 1.

[0052] When the silicon raw materials pass through the fixed pipe, the nozzle 123 changes the direction of the jet in the reaction chamber during the water spraying process, using the reaction force of the water to drive the rotation of the second annular pipe 124 relative to the fixed pipe, so as to expand the jet range.

[0053] In order to enhance the collision effect between silicon droplets in the reaction chamber, at least one set of the aforementioned nozzle structure arranged in the reaction chamber through the second connecting pipe is installed on the upper feeding end 120a.

[0054] The buffer cylinder 2 is connected to the bottom end of the reaction cylinder 1 and can be integrally formed with the reaction cylinder 1. When the blocking valve 21 of the buffer cylinder 2 is in an open state, the products in the reaction chamber, hydrogen, hydrogen chloride and other harmful gases generated in the reaction can be outputted outwards. The buffer cylinder 2 is also provided with a charging and exhausting device, which can be arranged below the blocking valve 21.

[0055] The forming cylinder 3 is connected to the bottom end of the buffer cylinder 2 and can be integrally formed with the buffer cylinder 2. The forming cylinder 3 can accommodate the products and harmful gases transported from the reaction cylinder 1 when the blocking valve 21 is open. A lower end 32 is arranged at the bottom end of the forming cylinder 3, and a lower valve 31 is arranged at the lower end 32 of the forming cylinder 3 to control the output of the products in the forming cylinder 3.

[0056] When the forming cylinder 3 is discharged before the material is discharged, the inert gas can be filled into the forming chamber by closing the blocking valve 21 and opening the charging and exhausting device to carry out gas replacement. After the gas replacement in the forming chamber is completed, the discharge of the forming cylinder 3 can be carried out by opening the discharge valve 31.

[0057] The raw material pretreatment unit has an atomizer 4 and a discharge pipeline 42. The input end of the discharge pipeline 42 is connected with the atomizer 4, and the output end thereof is connected with the upper feeding end 120a and the lower feeding end 120b respectively. Specifically, the connection of the discharge pipeline 42 with the first connecting pipe or the second connecting pipe can realize the connection of the discharge pipeline 42 with the reaction cylinder 1. In order to control the discharge amount of the atomizer 4, the discharge pipeline 42 is provided with a discharge valve 41. The atomizer 4 can be any one of a thermal vaporizer, an ultrasonic atomizer, a compressed atomizer and a bubbling atomizer. Through the atomizer 4, the liquid silicon-containing material forms steam or aerosol, which is convenient for being sent into the reaction cylinder 1.

[0058] Based on the above embodiment, the working mode of the present application is as follows:

[0059] (1) Plasma reaction: open the blocking valve 21 and close the discharge valve 31. The silicon raw material treated by the atomizer 4 is transmitted to the upper feeding end 120a and the lower feeding end 120b through the discharge pipeline 42, and then enters the reaction chamber to carry out plasma reaction to form small silicon droplets. The feeding of the upper feeding end 120a drives the rotation of the second annular pipe 124, so that the nozzle 123 arranged on the second annular pipe 124 can be sprayed at a variable angle.

[0060] (2) Cooling and forming: the silicon droplets formed by the plasma reaction fall into the forming chamber to be cooled and formed. When the material in the forming chamber accumulates to a certain amount, the blocking valve 21 is closed, and the charging and exhausting device is started to replace the harmful gas in the forming chamber. After the gas replacement is completed, the discharge of the forming cylinder 3 can be carried out by opening the discharge valve 31.

[0061] Based on the above embodiment, the advantages of the present application are as follows:

[0062] (1) The feeding of the upper feeding end 120a forms silicon droplets, which disturb the silicon droplets in the reaction chamber, which is beneficial to improve the yield of polysilicon particles and improve the production efficiency.

[0063] (2) The plasma reaction carried out by the device is not only suitable for a wide range of raw materials, but also eliminates the process of pre-distillation and purification of the material in the traditional method, thereby reducing the investment cost. Compared with the traditional method of producing polysilicon by using the Siemens method or the silane fluidized bed method, the device has small size and small floor area, and can avoid the use of crystal seeds.

Claims

1. An apparatus for preparing polycrystalline silicon, characterized in that, The device includes: The plasma reaction unit is divided into a reaction cylinder and a forming cylinder from top to bottom. The reaction cylinder is provided with a multi-stage feed end below the plasma generator; a homogenizer is installed inside the reaction cylinder, which divides the multi-stage feed end into an upper feed end and a lower feed end; each feed end is equipped with a nozzle group arranged circumferentially around the cross-section of the reaction cylinder for multi-angle injection of silicon raw material. The forming cylinder is used for cooling and forming silicon droplets, and its discharge end is equipped with a discharge valve; The raw material pretreatment unit has an atomizer connected to the feed end of the reaction cylinder via a discharge pipe.

2. The apparatus for preparing polycrystalline silicon according to claim 1, characterized in that: The nozzle assembly can be installed in the reaction cylinder in two ways: the nozzle assembly is installed inside the reaction cylinder through a first connecting pipe surrounding the outer wall of the reaction cylinder, and is used to spray silicon raw material into the reaction cylinder from the outside to the inside of the reaction cylinder; or the nozzle assembly is installed inside the reaction cylinder through a second connecting pipe, so that silicon raw material is sprayed into the reaction chamber from the inside to the outside of the reaction cylinder.

3. The apparatus for preparing polycrystalline silicon according to claim 2, characterized in that: The multi-stage feed end is equipped with any one type of nozzle group or a combination of two nozzle groups.

4. The apparatus for preparing polycrystalline silicon according to claim 3, characterized in that: The first connecting pipe includes a first annular pipe and multiple branch pipes; The outer wall of the first annular pipe is connected to the discharge pipe; the first annular pipe surrounds the outer wall of the reaction cylinder; Multiple diversion tubes are provided, one end of which is connected at intervals along the circumference of the first annular tube to the inner wall of the first annular tube, and the other end of which passes through the reaction cylinder and is fitted with a nozzle.

5. The apparatus for preparing polycrystalline silicon according to claim 3, characterized in that: The second connecting pipe includes a second annular pipe, an mounting pipe, and a fixing pipe; the second annular pipe is disposed inside the reaction cylinder; the nozzles are installed at intervals along the circumference of the second annular pipe on the outer wall of the second annular pipe; the second annular pipe is connected to the fixing pipe through the mounting pipe; the fixing pipe is connected to the discharge pipe.

6. The apparatus for preparing polycrystalline silicon according to claim 5, characterized in that: The nozzle adopts a bent tube structure; one end of the mounting tube is connected to the second annular tube, and the other end is rotatably connected to the fixed tube, so as to allow the nozzle assembly to rotate around the axial direction of the reaction cylinder.

7. The apparatus for preparing polycrystalline silicon according to claim 6, characterized in that: The installation pipe consists of a main pipe and multiple branch pipes; the multiple branch pipes are arranged circumferentially along the second annular pipe with one end connected to the inner wall of the second annular pipe, and the other end extends toward the center of the second annular pipe and merges with one end of the main pipe. The fixed pipe consists of a vertical pipe section and a horizontal pipe section; one end of the vertical pipe section is rotatably connected to the other end of the main pipe, and the other end of the vertical pipe section is connected to one end of the horizontal pipe section. The other end of the horizontal pipe section extends outward through the side wall of the reaction cylinder to connect with the discharge pipe.

8. The apparatus for preparing polycrystalline silicon according to claim 6, characterized in that: The upper feed end is equipped with a nozzle assembly located inside the reaction cylinder via a second connecting pipe.

9. The apparatus for preparing polycrystalline silicon according to claim 1, characterized in that: The reaction cylinder and the forming cylinder are connected vertically via a buffer cylinder; the buffer cylinder is equipped with a baffle valve to control the communication or blockage between the inner chambers of the reaction cylinder and the forming cylinder; the buffer cylinder is also equipped with a filling and venting device, which is located below the baffle valve; the gas replacement inside the forming cylinder is achieved through the cooperation of the discharge valve and the baffle valve.

10. The apparatus for preparing polycrystalline silicon according to claim 1, characterized in that: The homogenizer consists of one or more perforated plates.

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