Feeding system of polycrystalline silicon reduction furnace

Abstract

The invention discloses a feeding system of a polycrystalline silicon reduction furnace, which comprises a tail gas tank, a dichlorosilane tank, a hydrogen tank, a trichlorosilane tank, a nitrogen tank and a reduction furnace body, and a first feeding control valve is arranged on a pipeline between the tail gas tank and the reduction furnace body. A second feeding control valve is arranged on the pipeline between the dichlorosilane tank and the reduction furnace body, the hydrogen tank and the trichlorosilane tank are both connected with a mixing cavity, the mixing cavity is connected with the reduction furnace body, and a third feeding control valve is arranged on the pipeline between the hydrogen tank and the mixing cavity. And a fourth feeding control valve is arranged on the pipeline between the trichlorosilane tank and the mixing cavity. According to the feeding system of the polycrystalline silicon reduction furnace, the feeding mode and components of the reduction furnace are changed, the deposition rate and the conversion rate of a reduction reaction can be increased, power consumption can be reduced, generation of amorphous shapes caused by uneven gas fields can be effectively controlled, the product quality can be improved, and the effect of low cost can be finally achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polycrystalline silicon production, and particularly relates to a feeding system of a polycrystalline silicon reduction furnace. BACKGROUND

[0002] The feeding system of the polycrystalline silicon reduction furnace is a supporting device for feeding in the production of polycrystalline silicon. At present, the production method of polycrystalline silicon mainly adopts the modified Siemens method. The main method is that the reaction gas trichlorosilane and hydrogen gas mixed in a certain proportion in the reduction furnace are subjected to a reduction reaction on the surface of a silicon core at high temperature, and the silicon atoms are chemically vapor deposited on the silicon core to form polycrystalline silicon. With the continuous development of science and technology, people's requirements for the feeding system of the polycrystalline silicon reduction furnace are also getting higher and higher.

[0003] The existing feeding system of the polycrystalline silicon reduction furnace has certain disadvantages in use. The conversion rate and deposition rate of the polycrystalline silicon produced by this method are low, and when the temperature control is uneven, amorphous silicon will be generated, which affects the external quality of the product. Moreover, the structure of the reduction furnace is to feed the mixed gas from the bottom, and the material is sprayed to the top of the reduction furnace by the feeding nozzle and the feeding pressure. However, when the material is sprayed to the top, there will be insufficient material, the temperature of the cross beam is too high, and the gas field distribution is uneven, which will cause the "bark" and "molten silicon" phenomena on the surface of the silicon rod during the production process, and also affect the product quality. Therefore, we propose a feeding system of a polycrystalline silicon reduction furnace. SUMMARY

[0004] The technical problem solved by the present application is that, in view of the deficiencies in the prior art, the present application provides a feeding system of a polycrystalline silicon reduction furnace, which changes the feeding method and components of the reduction furnace, can improve the deposition rate and conversion rate of the reduction reaction, reduce power consumption, effectively control the generation of amorphous caused by uneven gas field, improve product quality, and ultimately achieve the effect of low cost, which can effectively solve the problems in the background art.

[0005] The technical scheme adopted by the present application is as follows: a feeding system of a polycrystalline silicon reduction furnace, comprising a tail gas tank, a dichlorosilane tank, a hydrogen tank, a trichlorosilane tank, a nitrogen tank and a reduction furnace body, a first feeding control valve is arranged on the pipeline between the tail gas tank and the reduction furnace body, a second feeding control valve is arranged on the pipeline between the dichlorosilane tank and the reduction furnace body, the hydrogen tank and the trichlorosilane tank are both connected with a mixing chamber, the mixing chamber is connected with the reduction furnace body, a third feeding control valve is arranged on the pipeline between the hydrogen tank and the mixing chamber, a fourth feeding control valve is arranged on the pipeline between the trichlorosilane tank and the mixing chamber, a fifth feeding control valve is arranged on the pipeline between the nitrogen tank and the reduction furnace body, a bottom disc is positioned and installed at the bottom of the reduction furnace body, a nozzle is installed at the center point in the reduction furnace body, feeding pipelines are uniformly distributed and arranged around the position of the nozzle in the reduction furnace body, and the nozzle comprises two structures.

[0006] As a preferred technical solution of the present application, in the first structure, the position of the nozzle is provided with a first extension piece, the first extension piece is positioned at the center point of the bottom disc, and the position of the first extension piece is connected with the dichlorodihydrogen silicon tank, the position of the feeding pipe is connected with the tail gas tank, the hydrogen tank, the trichlorosilane tank and the nitrogen tank, the first extension piece is fed at 2 / 3 of the height of the middle and upper silicon core, and four gas outlets are arranged at the top.

[0007] As a preferred technical solution of the present application, in the second structure, the position of the nozzle is provided with a second extension piece, the top of the second extension piece is positioned with a shunt assembly, the second extension piece is positioned at the center point of the bottom disc, and the second extension piece is connected with the dichlorodihydrogen silicon tank, the second extension piece is fed at a position 10 cm higher than the top of the silicon core, and four gas injection holes are arranged on the four sides of the nozzle, corresponding to four tail gas holes.

[0008] As a preferred technical solution of the present application, the output ends of the tail gas tank, the hydrogen tank, the trichlorosilane tank and the nitrogen tank are connected with the feeding pipe to pump the material into the inside of the reduction furnace body, and the distribution is controlled by the first feeding control valve, the third feeding control valve, the fourth feeding control valve and the fifth feeding control valve.

[0009] As a preferred technical solution of the present application, the output end of the dichlorodihydrogen silicon tank is connected with the nozzle to pump the material into the inside of the reduction furnace body, and the control is performed by the second feeding control valve.

[0010] As a preferred technical solution of the present application, it specifically includes the following operation steps: S1: A plurality of pairs of rod reduction furnaces and reduction furnace mixed gas feeding pipes are arranged around the furnace body bottom disc, and a dichlorodihydrogen silicon feeding pipe is arranged at the most central position of the furnace body bottom disc; S2: The central nozzle is provided with two extension piece structures, which are a first extension piece structure and a second extension piece structure, the first extension piece structure is fed at 2 / 3 of the height of the middle and upper silicon core, four gas outlets are arranged at the top of the nozzle, the second extension piece structure is fed at a position 10 cm higher than the top of the silicon core, and four gas injection holes are arranged on the four sides of the nozzle, corresponding to four tail gas holes; S3: Before the reduction furnace is installed with a silicon core, the nozzle extension piece is installed at the central nozzle position, the extension root is a threaded structure, and it needs to be confirmed to be fastened; S4: After the reduction furnace is broken through, according to the normal production procedure, the hydrogen valve is opened, and a certain flow of hydrogen is introduced into the reduction furnace; S5: The valve of dichlorodihydrogen silicon is opened, the flow is controlled by adjusting the valve, 100 kg of dichlorodihydrogen silicon is introduced into the reduction furnace, at the same time that the dichlorodihydrogen silicon adjusting valve is opened, the valve of trichlorosilane is opened, and 3000 kg of trichlorosilane is introduced into the reduction furnace by adjusting the valve; S6: 30 hours before the reduction furnace is operated, the material is taken out according to the set material table, and the flow rate ratio of dichlorodihydrogen silicon is controlled to be 3%-4% of the total flow rate; S7: 30 hours after the reduction furnace is operated to the shutdown of the reduction furnace, the flow rate ratio of dichlorodihydrogen silicon is controlled to be greater than 4% and less than 10% of the total flow rate, and the ratio in the later period is slightly larger to maintain the reaction temperature in the later period; S8: when the reduction furnace is shut down, the dichlorodihydrogen silicon and trichlorohydrogen silicon are slowly reduced to the initial condition, the dichlorodihydrogen silicon valve is closed, and then the trichlorohydrogen silicon valve is closed; S9: when the reduction furnace is disassembled, since the nozzle extension is arranged at the center, the disassembly of the manipulator is not affected, and after the silicon rod is disassembled, the nozzle can be screwed off for inspection and cleaning.

[0011] As a preferred technical solution of the present application, in the S1 step, the dichlorodihydrogen silicon is directly supplied to the reduction from the raw material workshop, the pressure is controlled to be the same as that of the trichlorohydrogen silicon and oxygen, and is generally controlled to be 0.8-0.9 MPa.

[0012] As a preferred technical solution of the present application, in the S4 step, when the pressure of the reduction furnace is 0.02 MP higher than that of the tail gas, the tail gas valve is opened, and after the system is connected, the temperature of the silicon core is raised to 1080 DEG C.

[0013] Beneficial effects: compared with the prior art, the present application provides a feeding system of a polysilicon reduction furnace, which has the following beneficial effects: the feeding system of the polysilicon reduction furnace changes the feeding mode and components of the reduction furnace, can improve the deposition rate and conversion rate of the reduction reaction, reduce power consumption, effectively control the generation of irregular shapes caused by uneven gas field, improve product quality, and ultimately achieve the effect of low cost; The byproduct dichlorodihydrogen silicon of the tail gas can be directly used for reduction. The change of the reduction feeding components can improve the reduction conversion rate and deposition rate, reduce power consumption, the change of the layout of the nozzle and the optimization of the feeding position can make the reaction gas field and temperature of the reduction furnace more uniform, improve product quality, and reduce the output of abnormal materials. The whole feeding system structure of the polysilicon reduction furnace is simple, convenient to operate, and has better effect than the traditional way. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a whole structure schematic view of the feeding system of the polysilicon reduction furnace.

[0015] Figure 2 It is a structure schematic view of the internal top view of the reduction furnace body in the feeding system of the polysilicon reduction furnace.

[0016] Figure 3It is a kind of polycrystalline silicon reduction furnace feeding system in the first structure of the schematic diagram of the internal structure of the reduction furnace body.

[0017] Figure 4 It is a kind of polycrystalline silicon reduction furnace feeding system in the first structure of the schematic diagram of the internal structure of the reduction furnace body.

[0018] Figure 5 It is a kind of polycrystalline silicon reduction furnace feeding system in the first structure of the schematic diagram of the internal structure of the reduction furnace body.

[0019] Figure 6 It is a kind of polycrystalline silicon reduction furnace feeding system in the first structure of the schematic diagram of the internal structure of the reduction furnace body.

[0020] In the figure: 1, tail gas tank; 2, first feeding control valve; 3, second feeding control valve; 4, nitrogen tank; 5, dichloro dihydrogen silicon tank; 6, hydrogen tank; 7, third feeding control valve; 8, trichloro hydrogen silicon tank; 9, fourth feeding control valve; 10, mixing cavity; 11, fifth feeding control valve; 12, reduction furnace body; 13, feeding pipeline; 14, nozzle; 15, bottom disc; 16, first extension; 17, second extension; 18, shunt assembly. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described clearly and completely in the following description in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application. The specific conditions are not specified in the embodiments, which are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, which are conventional products that can be purchased on the market.

[0022] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship 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. In addition, the terms "first", "second", "third" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present application, it should be noted that unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside 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.

[0024] As Figures 1-6 The feeding system of the polycrystalline silicon reduction furnace includes a tail gas tank 1, a dichlorosilane tank 5, a hydrogen tank 6, a trichlorosilane tank 8, a nitrogen tank 4 and a reduction furnace body 12. A first feeding control valve 2 is arranged on the pipeline between the tail gas tank 1 and the reduction furnace body 12. A second feeding control valve 3 is arranged on the pipeline between the dichlorosilane tank 5 and the reduction furnace body 12. The hydrogen tank 6 and the trichlorosilane tank 8 are both connected with a mixing chamber 10. The mixing chamber 10 is connected with the reduction furnace body 12. A third feeding control valve 7 is arranged on the pipeline between the hydrogen tank 6 and the mixing chamber 10. A fourth feeding control valve 9 is arranged on the pipeline between the trichlorosilane tank 8 and the mixing chamber 10. A fifth feeding control valve 11 is arranged on the pipeline between the nitrogen tank 4 and the reduction furnace body 12. A bottom disc 15 is arranged at the bottom of the reduction furnace body 12. A nozzle 14 is arranged at the center point inside the reduction furnace body 12. Feeding pipelines 13 are uniformly arranged around the nozzle 14 inside the reduction furnace body 12. The nozzle 14 includes two structures, which changes the feeding mode and components of the reduction furnace, can improve the deposition rate and conversion rate of the reduction reaction, reduce the power consumption, effectively control the generation of irregular shapes caused by uneven gas field, improve the product quality, and finally achieve the effect of low cost.

[0025] Further, in the first structure, the nozzle 14 is provided with a first extension piece 16. The first extension piece 16 is positioned at the center point of the bottom disc 15. The first extension piece 16 is connected with the dichlorosilane tank 5. The feeding pipelines 13 are connected with the tail gas tank 1, the hydrogen tank 6, the trichlorosilane tank 8 and the nitrogen tank 4. The first extension piece 16 feeds at the position of 2 / 3 of the height of the silicon core from the top, and four gas outlets are arranged at the top.

[0026] Further, in the second structure, the nozzle 14 is provided with a second extension piece 17. The second extension piece 17 is positioned at the center point of the bottom disc 15. The second extension piece 17 is connected with the dichlorosilane tank 5. The second extension piece 17 feeds at the position of 10 cm higher than the silicon core from the top. Four gas injection holes are arranged on the four sides, corresponding to four tail gas holes.

[0027] Further, the output ends of the tail gas tank 1, the hydrogen tank 6, the trichlorosilane tank 8 and the nitrogen tank 4 pump the materials into the inside of the reduction furnace body 12 through the feeding pipeline 13, and the distribution is controlled through the first feeding control valve 2, the third feeding control valve 7, the fourth feeding control valve 9 and the fifth feeding control valve 11.

[0028] Further, the output end of the dichlorosilane tank 5 pumps the material into the inside of the reduction furnace body 12 through the nozzle 14, and is controlled through the second feeding control valve 3.

[0029] Further, the specific operation steps include the following steps: S1: A plurality of pairs of rod reduction furnaces and reduction furnace mixed gas feeding pipelines enter the furnace body bottom plate around, and the dichlorosilane feeding pipeline enters the most central position of the furnace body bottom plate; S2: The central nozzle is provided with two kinds of extension structure, which are respectively a first extension structure and a second extension structure, the first extension structure is to feed at the height of 2 / 3 of the silicon core, and the top of the nozzle is provided with 4 gas outlets, and the second extension structure is to feed at the top which is higher than the silicon core by 10 cm, and the nozzle is provided with 4 jet holes on four sides, corresponding to 4 tail gas holes; S3: Before the reduction furnace is installed with the silicon core, the nozzle extension is installed to the central nozzle position, the extension root is a threaded structure, and needs to be confirmed to be fastened; S4: After the reduction furnace is broken down, according to the normal production procedure, the hydrogen valve is opened, and a certain flow of hydrogen is introduced into the reduction furnace; S5: The valve of the dichlorosilane is opened, the flow is controlled through the regulating valve, 100 kg of dichlorosilane is introduced into the reduction furnace, at the same time of opening the dichlorosilane regulating valve, the valve of the trichlorosilane is opened, and 3000 kg of trichlorosilane is introduced into the reduction furnace through the regulating valve; S6: 30 hours before the reduction furnace is operated, the material is lifted according to the set material table, and the flow ratio of the dichlorosilane introduced is controlled to be 3%-4% of the total flow; S7: From 30 hours of the operation of the reduction furnace to the shutdown of the reduction furnace, the flow ratio of the dichlorosilane introduced is controlled to be greater than 4% of the total flow, and does not exceed 10%, and the ratio in the later period is slightly larger to maintain the reaction temperature in the later period; S8: When the reduction furnace is shut down, the dichlorosilane and the trichlorosilane are slowly reduced to the initial condition, the dichlorosilane valve is closed, and then the trichlorosilane valve is closed; S9: When the reduction furnace is disassembled, since the nozzle extension is arranged at the most center, it does not affect the disassembly of the mechanical hand, after the silicon rod is disassembled, the nozzle can be screwed off for inspection and cleaning.

[0030] Further, in the S1 step, the dichlorosilane is directly supplied from the raw material workshop for reduction, the pressure is controlled to be the same as that of the trichlorosilane and oxygen, and is generally controlled to be 0.8-0.9 MPa.

[0031] Further, when the furnace pressure in the S4 step is reduced to 0.02 MPa higher than the tail gas pressure, the tail gas valve is opened, and after the system is connected, the temperature of the silicon core is raised to 1080 DEG C.

[0032] Working principle: the present application comprises a tail gas tank 1, a first feed control valve 2, a second feed control valve 3, a nitrogen tank 4, a dichlorosilane tank 5, a hydrogen tank 6, a third feed control valve 7, a trichlorosilane tank 8, a fourth feed control valve 9, a mixing cavity 10, a fifth feed control valve 11, a reduction furnace body 12, a feed pipeline 13, a nozzle 14, a base plate 15, a first extension 16, a second extension 17, a flow distribution assembly 18, the feed mode and components of the reduction furnace are changed, the deposition rate and conversion rate of the reduction reaction can be improved, the power consumption is reduced, the generation of irregular shapes caused by uneven gas field is effectively controlled, the product quality is improved, and the effect of low cost is finally achieved.

[0033] The present application comprises multiple pairs of rod reduction furnaces, reduction furnace mixed gas feed pipelines, dichlorosilane feed pipelines and nozzle extensions; The reduction furnace is divided into two feed pipelines, which are a mixed gas feed pipeline of hydrogen and trichlorosilane, and a dichlorosilane feed pipeline, which are extended to the periphery of the base plate and the center of the base plate, respectively; The dichlorosilane is a liquid feed, which is directly supplied to the reduction furnace from the raw material workshop, according to the material characteristics of dichlorosilane, the boiling point is low, according to the maximum heat field temperature at the center of the reduction furnace during operation, the reduction workshop does not need to set a vaporizer or a heat exchanger to heat the dichlorosilane alone, and the liquid feed at the center can achieve the effect of optimizing the temperature field; The nozzle extension is a modified part of the dichlorosilane feed nozzle; The reduction furnace is installed with the nozzle extension before the silicon core is loaded; During the operation of the reduction furnace, the mixed gas enters the reduction furnace from the bottom of the reduction furnace; The dichlorosilane feed mode is changed, and the nozzle extension enters the reduction furnace into the upper part or the top of the silicon rod; The two kinds of materials are mixed in a certain proportion to produce polysilicon, a fast silicon deposition rate can be obtained, the thickness deposition rate is greater than 1.5 mm per hour, the temperature of the upper part of the silicon rod and the gas field of the entire reduction furnace can be optimized, and the generation of irregular silicon is reduced; The nozzle extension is arranged at the center position, which does not affect the disassembly operation, and can be disassembled for cleaning and inspection after the furnace is disassembled.

[0034] Multiple pairs of rod reduction furnaces and reduction furnace mixed gas feed pipelines are arranged to enter the furnace body base plate periphery, and the dichlorosilane feed pipeline enters the furnace body base plate center position; The center nozzle is provided with two extension structures, namely a first extension structure and a second extension structure, the first extension structure is to feed at a position of 2 / 3 of the height of the upper part of the silicon core, four gas outlets are arranged at the top of the nozzle, the second extension structure is to feed at a position of 10 cm higher than the silicon core, four gas injection holes are arranged on the four sides of the nozzle, corresponding to four tail gas holes; before the reduction furnace is installed with the silicon core, the nozzle extension is installed to the center nozzle position, the extension root is a threaded structure, and fastening needs to be confirmed; after the reduction furnace is broken through, according to the normal production procedure, the hydrogen valve is opened, a certain flow of hydrogen is introduced into the reduction furnace; the dichlorodihydrogen silicon valve is opened, the flow is controlled by the regulating valve, 100 kg of dichlorodihydrogen silicon is introduced into the reduction furnace, at the same time that the dichlorodihydrogen silicon regulating valve is opened, the trichlorohydrogen silicon valve is opened, 3000 kg of trichlorohydrogen silicon is introduced into the reduction furnace by the regulating valve; 30 hours before the reduction furnace is operated, the material is lifted according to the set material table, the flow ratio of the introduced dichlorodihydrogen silicon is controlled to be 3%-4% of the total flow; from 30 hours of the operation of the reduction furnace to the shutdown of the reduction furnace, the flow ratio of the introduced dichlorodihydrogen silicon is controlled to be greater than 4% and not more than 10% of the total flow, the ratio in the later period is slightly larger to maintain the reaction temperature in the later period; when the reduction furnace is shut down, the dichlorodihydrogen silicon and the trichlorohydrogen silicon are slowly reduced to the initial condition together, the dichlorodihydrogen silicon valve is closed, and then the trichlorohydrogen silicon valve is closed; when the reduction furnace is disassembled, since the nozzle extension is arranged at the most center position, the disassembly of the mechanical hand is not affected, after the silicon rod is disassembled, the nozzle can be screwed off for inspection and cleaning.

[0035] It should be noted that the relational terms herein such as first and second (one and two) are used only to differentiate one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or equipment including the element.

[0036] The basic principles and main features of the present application and the advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, the above examples and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the present application.

Claims

1. A feeding system for a polycrystalline silicon reduction furnace, comprising a tail gas tank (1), a dichlorosilane tank (5), a hydrogen tank (6), a trichlorosilane tank (8), a nitrogen tank (4), and a reduction furnace body (12), characterized in that: A first feed control valve (2) is installed on the pipeline between the tail gas tank (1) and the reduction furnace body (12). A second feed control valve (3) is installed on the pipeline between the dichlorosilane tank (5) and the reduction furnace body (12). The hydrogen tank (6) and the trichlorosilane tank (8) are both connected to a mixing chamber (10). The mixing chamber (10) is connected to the reduction furnace body (12). A third feed control valve (7) is installed on the pipeline between the hydrogen tank (6) and the mixing chamber (10). The trichlorosilane tank (8) A fourth feed control valve (9) is provided on the pipe between the nitrogen tank (4) and the mixing chamber (10), and a fifth feed control valve (11) is provided on the pipe between the nitrogen tank (4) and the reduction furnace body (12). A chassis (15) is installed at the bottom of the reduction furnace body (12). A nozzle (14) is installed at the center point inside the reduction furnace body (12). Feed pipes (13) are evenly distributed around the nozzle (14) inside the reduction furnace body (12). The nozzle (14) includes two structures.

2. The feeding system for a polycrystalline silicon reduction furnace according to claim 1, characterized in that: In the first structure, the nozzle (14) is provided with a first extension (16), the first extension (16) is positioned at the center point of the chassis (15), and the position of the first extension (16) is connected to the dichlorosilane tank (5). The position of the feed pipe (13) is connected to the tail gas tank (1), the hydrogen tank (6), the trichlorosilane tank (8) and the nitrogen tank (4). The first extension (16) is for feeding at 2 / 3 of the height of the silicon core in the middle and upper part, and 4 gas outlets are provided at the top.

3. The feeding system for a polycrystalline silicon reduction furnace according to claim 1, characterized in that: In the second structure, a second extension (17) is provided at the position of the nozzle (14). A diversion component (18) is positioned at the top of the second extension (17). The second extension (17) is positioned at the center point of the chassis (15). The second extension (17) is connected to the dichlorosilane canister (5). The second extension (17) is fed 10cm above the silicon core at the top. A total of 4 jet holes are provided on the four sides, corresponding to 4 exhaust holes.

4. The feeding system for a polycrystalline silicon reduction furnace according to claim 1, characterized in that: The output ends of the tail gas tank (1), hydrogen tank (6), trichlorosilane tank (8) and nitrogen tank (4) pump the material into the interior of the reduction furnace body (12) through the feed pipe (13), and the distribution is controlled by the first feed control valve (2), the third feed control valve (7), the fourth feed control valve (9) and the fifth feed control valve (11).

5. The feeding system for a polycrystalline silicon reduction furnace according to claim 1, characterized in that: The output end of the dichlorosilane tank (5) pumps the material into the interior of the reduction furnace body (12) through the nozzle (14), and is controlled by the second feed control valve (3).

6. The feeding system for a polycrystalline silicon reduction furnace according to claim 1, characterized in that: Specifically, the following steps are included: S1: Set up multiple pairs of rod reduction furnaces and the mixed gas feed pipes of the reduction furnace to enter the furnace body chassis around the perimeter, and the dichlorosilane feed pipe to enter the center of the furnace body chassis. S2: The center nozzle is equipped with two extension structures, namely the first extension structure and the second extension structure. The first extension structure feeds at 2 / 3 of the height of the silicon core in the middle and upper part, and four air outlets are set at the top of the nozzle. The second extension structure feeds at the top 10cm above the silicon core, and four air jet holes are set on the four sides of the nozzle, corresponding to four exhaust holes. S3: Before installing the silicon core in the reduction furnace, install the nozzle extension to the center nozzle position. The root of the extension has a threaded structure, and you need to confirm that it is tight. S4: After the reduction furnace breaks down, open the hydrogen valve according to the normal production procedure and introduce a certain flow of hydrogen into the reduction furnace. S5: Open the valve of dichlorosilane, control the flow rate through the regulating valve, and introduce 100 kg of dichlorosilane into the reduction furnace. At the same time as opening the dichlorosilane regulating valve, open the valve of trichlorosilane, and control the flow rate through the regulating valve to introduce 3000 kg of trichlorosilane into the reduction furnace. S6: 30 hours before the reduction furnace starts operation, feed materials according to the set material list, and control the proportion of dichlorosilane fed in at 3%-4% of the total flow rate; S7: During the 30 hours of operation of the reduction furnace until the furnace is shut down, the proportion of dichlorosilane introduced should be greater than 4% of the total flow rate but not more than 10%. A slightly higher proportion in the later stages can maintain the reaction temperature in the later stages. S8: When the reduction furnace is shut down, dichlorosilane and trichlorosilane are slowly reduced to the initial conditions together, the dichlorosilane valve is closed, and then the trichlorosilane valve is closed; S9: When dismantling the reduction furnace, since the nozzle extension is set at the very center, it does not affect the disassembly and assembly of the robotic arm. After the silicon rod is removed, the nozzle can be unscrewed for inspection and cleaning.

7. The feeding system for a polycrystalline silicon reduction furnace according to claim 6, characterized in that: In step S1, dichlorosilane is supplied directly from the raw material workshop for reduction, and the pressure is controlled to be the same as that of trichlorosilane and oxygen, generally controlled at 0.8MPa-0.9MPa.

8. The feeding system for a polycrystalline silicon reduction furnace according to claim 6, characterized in that: In step S4, when the pressure in the reduction furnace reaches 0.02 MPa higher than the tail gas pressure, the tail gas valve is opened, and after the system is connected, the temperature of the silicon core is raised to 1080°C.

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