CN102674363A - Double-layer structure of inner container of energy-saving type polysilicon reduction furnace and implementation method for double-layer structure - Google Patents

Abstract

The invention discloses a double-layer structure of an inner tank of an energy-saving polysilicon reduction furnace and an implementation method thereof. The inner tank of a polysilicon reduction furnace includes a two-layer structure of an inner wall and an outer wall, and the gap between the inner wall and the outer wall is between the top bottom plate and the top plate of the inner tank. The area is connected; the width of the gap between the inner wall and the outer wall is 5mm-50mm. The high-purity trichlorosilane liquid is passed between the inner wall and the outer wall of the inner tank of the polysilicon reduction furnace. Because a large amount of heat in the reduction furnace radiates to the side of the inner tank, the liquid trichlorosilane is heated and volatilized, and the gas generated by volatilization flows into the inner tank. The area between the top base plate and the top plate. The double-layer structure of the inner tank can greatly reduce the radiation energy of the silicon rods to the inner wall of the bell jar. The inner wall of the bell jar will not deposit silicon powder due to the lower temperature, which maintains the polishing effect of the inner wall of the bell jar and can also reduce the cooling water of the bell jar of the polysilicon reduction furnace. throughput. The energy radiated by the silicon rod is used to make part of the liquid trichlorosilane into a gas to participate in the reaction, which is beneficial to the reduction of the overall energy consumption in the polysilicon preparation process.

Description

An energy-saving polysilicon reduction furnace with a double-layer structure of the inner tank and its implementation method

technical field

The invention belongs to the technical field of polysilicon production, in particular to an energy-saving large-scale polysilicon reduction furnace for producing polysilicon by the Siemens method; it relates to an energy-saving polysilicon reduction furnace with a double-layer inner container structure and an implementation method thereof.

background introduction

Polysilicon is widely used in the fields of electronics and solar energy. At present, polysilicon manufacturers at home and abroad mainly use the "improved Siemens method". The production process of this method is to use chlorine and hydrogen to synthesize hydrogen chloride (or purchased hydrogen chloride), hydrogen chloride and silicon powder react at a certain temperature to form trichlorosilane, and then carry out rectification separation and purification of trichlorosilane, and the purified high After the pure trichlorosilane and hydrogen are mixed in proportion, they are passed into the polysilicon reduction furnace at a certain temperature and pressure, and the deposition reaction is carried out on the electrified high-temperature silicon core to form polysilicon. The reaction temperature is controlled at 1080 ° C ~ 1150 ° C, and finally produces Rod-shaped polysilicon products produce by-products such as silicon tetrachloride, dichlorodihydrosilane, and hydrogen chloride at the same time.

Traditional polysilicon reduction furnaces, such as patents CN200420060144.8, CN200720306394.9, CN200820105591.9, CN200920230836.5, CN201020215600.7, etc., its air inlet and outlet are distributed on the chassis, the disadvantage of this design is due to the flow field , the matching of the temperature field is unreasonable, and it is easy to stay at the top of the reduction furnace, resulting in a flow dead zone, causing the gas temperature in the local area to be too high, and producing silicon powder. Silicon powder is easy to adhere to the inner wall of the bell jar, which reduces the smoothness of the inner wall of the bell jar, causing the energy taken away by radiation to soar, and finally manifested as an increase in reduction power consumption; in addition, because the inlet fluid flows upward, the outlet fluid flows downward. Flow, these two counter-flowing fluids make the fluid in the reduction furnace in a mixed flow state, which affects the conversion rate of the reaction gas and further increases the power consumption of the reduction furnace. Through an industrial experiment conducted in a polysilicon production enterprise, our research group found that when the inner wall of the bell jar is a mirror surface, the reduction power consumption will be significantly reduced. Therefore, this research group proposes to transform the energy-saving problem of the reduction furnace into an operational problem of how to keep the inner wall of the bell jar of the reduction furnace in a mirror state during the polysilicon reduction process. For this reason, through in-depth theoretical calculations, the research group found that by making the gas phase in the reduction furnace realize plug flow, the gas phase temperature of the inner tank of the reduction furnace can be lower than 550°C. The temperature of the wall surface is lower than 575°C, so that the inner wall of the bell jar of the reduction furnace is always kept in a mirror state. On the basis of the above experiments and theoretical research, this research group designed an energy-saving polysilicon reduction furnace, and proposed the double-layer structure and implementation method of the heat preservation inner tank of the reduction furnace.

Contents of the invention

The invention provides an energy-saving polysilicon reduction furnace with a double-layer inner tank structure and its implementation method, which solves the problem of silicon powder deposited on the inner wall of the bell jar of the traditional polysilicon reduction furnace

Technical scheme of the present invention is as follows:

An energy-saving polysilicon reduction furnace with a double-layer inner tank structure. The inner tank of the polysilicon reduction furnace includes a two-layer structure of an inner wall 20 and an outer wall 21. The area is connected, and the connection between the inner wall 20 and the top bottom plate 22 and the connection between the outer wall 21 and the top top plate 23 are connected. The width of the gap between the inner wall 20 and the outer wall 21 is 5mm-50mm, and the distance between the bottom plate 22 and the top plate 23 is 100mm-300mm ;

The bottom plate 22 at the top of the polysilicon reduction furnace liner is fixedly connected with the inner wall 20 of the liner, and the top plate 23 at the top of the liner is fixedly connected with the outer wall of the liner 21 by bolts.

The high-purity trichlorosilane liquid is passed between the inner wall 20 and the outer wall 21 of the inner tank of the polysilicon reduction furnace. Since a large amount of heat in the reduction furnace radiates to the side of the inner tank, the liquid trichlorosilane is volatilized by heat, and the volatilized The gas flows into the area between the bottom plate 22 and the top plate 23 of the inner tank top.

If required in production, a temperature probe can be installed in the gap between the inner wall 20 and the outer wall 21 of the liner.

The advantage that the present invention has is:

First of all, compared with the traditional polysilicon reduction furnace, the double-layer structure of the inner tank can greatly reduce the radiation energy of the silicon rods to the inner wall of the bell jar. The inner wall of the bell jar will not deposit silicon powder due to the lower temperature, and the polishing effect of the inner wall of the bell jar is maintained. It can reduce the intake of cooling water for the bell jar of the polysilicon reduction furnace.

Compared with the traditional polysilicon reduction furnace again, liquid high-purity trichlorosilane is introduced into the inner wall and outer wall of the inner tank. Since the boiling point of trichlorosilane is lower, the heat radiated from the silicon rods to the side wall of the inner tank passes through The heat conduction heats the liquid trichlorosilane, so that part of the liquid trichlorosilane becomes gas. Since the side wall of the inner tank is connected with the top structure, the gaseous trichlorosilane enters the top area of the inner tank, and then passes through the inner tank. The air return pipe at the top of the tank enters the reaction area to participate in the reaction. Liquid trichlorosilane is injected into the side wall of the inner tank to ensure that the temperature of the inner tank will not be too high, which is conducive to safe production. The energy radiated by the silicon rods turns part of the liquid trichlorosilane into gas to participate in the reaction, which is beneficial to the reduction of the overall energy consumption in the polysilicon preparation process.

Description of drawings

Fig. 1 is a front view of an energy-saving polysilicon reduction furnace of the patent of the present invention;

Figure 2 is a schematic diagram of the double-layer structure of the inner tank of an energy-saving polysilicon reduction furnace of the patent of the present invention;

Among them: 1-reduction furnace bell jar, 2-insulation liner, 3-silicon core, 4-chassis, 5-chassis inlet pipe, 6-chassis outlet pipe, 7-electrode, 8-graphite jacket, 9-furnace body Cooling water inlet, 10-cooling water outlet of the furnace body, 11-chassis air intake control device, 12-chassis drain pipe, 13-chassis liquid trichlorosilane inlet pipe, 14-liquid trichlorosilane inlet pipe at the top of the liner , 15- liquid trichlorosilane inlet pipe on the side wall of the inner tank, 16- chassis cooling air box, 17- air outlet pipe on the top of the inner tank, 18- return air pipe on the top of the inner tank, 19- chassis exhaust control device, 20- inner tank The inner wall of the inner container, the outer wall of the 21-inner container, the top bottom plate of the 22-inner container, and the top top plate of the 23-inner container.

Detailed ways

A polysilicon reduction furnace equipped with a chassis cooling device provided by the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the reduction furnace bell jar 1 is fixed on the reduction furnace chassis 4 and sealed, the silicon core 3 is connected and sealed with the chassis electrode 7 through the graphite jacket 8, and the chassis electrode 7 is fixed to the reduction furnace chassis 4 and sealed, And be connected with the power supply system; The liquid trichlorosilane enters the chassis cooling gas box 16 of the polysilicon reduction furnace through the liquid trichlorosilane inlet pipe 13 of the chassis, and the liquid trichlorosilane enters the top of the polysilicon reduction furnace through the liquid trichlorosilane inlet pipe 14 at the top of the liner, and the liquid trichlorosilane Chlorosilane enters the polysilicon reduction furnace liner side wall through the liquid trichlorosilane inlet pipe 15 on the side wall of the inner tank, and the reduction furnace chassis 4 and the reduction furnace bell jar 1 pass through the cooling water inlet of the chassis and the cooling water inlet of the furnace body respectively. Water, and the chassis cooling water outlet and the furnace body cooling water outlet are respectively connected to the heat-requiring system.

Embodiment 1: Operation process 1 of the novel polysilicon reduction furnace:

(1) First turn on the chassis air intake control device 11 and the chassis exhaust control device 19;

(2) Next, cooling water is introduced into the body of the reduction furnace and the chassis of the reduction furnace at the same time, and the liquid trichlorosilane is passed into the side wall of the inner tank of the polysilicon reduction furnace through the liquid trichlorosilane inlet pipe 15 on the side wall of the inner tank. The gap width between the inner wall of the liner and the outer wall of the liner is 5 mm, and the distance between the bottom plate 22 and the top plate 23 is 100 mm;

(3) Mix the purified SiHCl ₃ and H ₂ in a certain proportion, and then pass the mixed gas into the polysilicon reduction furnace from the chassis intake pipe 5;

(4) Start the power supply system of the reduction furnace to heat the silicon core, and keep the temperature of the silicon core at 1150°C, and the pressure in the reduction furnace is 0.8Mpa. When the temperature of the surface of the silicon core reaches the conditions for the reaction of SiHCl ₃ and H ₂ , the mixed gas begins to undergo a reduction reaction, and the reacted silicon will be deposited on the silicon core, and the temperature of the inner wall of the bell jar of the polysilicon reduction furnace can be found by measuring the temperature with a temperature probe Always below 550°C;

(5) The exhaust gas after the reaction is discharged through the chassis outlet pipe 6, and the temperature of the exhaust gas is controlled at 350 ° C ± 20. When the diameter of the silicon core grows to more than 200 mm, stop power supply, and wait until the silicon core cools down, take out the silicon core, and pass It is estimated that the energy saving is about 15%.

Embodiment 2: Operation process 2 of the novel polysilicon reduction furnace:

(1) First turn on the chassis air intake control device 11 and the chassis exhaust control device 19;

(2) Next, cooling water is introduced into the body of the reduction furnace and the chassis of the reduction furnace at the same time, and the liquid trichlorosilane is passed into the side wall of the inner tank of the polysilicon reduction furnace through the liquid trichlorosilane inlet pipe 15 on the side wall of the inner tank. The gap width between the inner wall of the liner and the outer wall of the liner is 25mm, and the distance between the bottom plate 22 and the top plate 23 is 200mm;

(3) Mix the purified SiHCl ₃ and H ₂ in a certain proportion, and then pass the mixed gas into the polysilicon reduction furnace from the chassis intake pipe 5;

(4) Start the power supply system of the reduction furnace to heat the silicon core, and keep the temperature of the silicon core at 1150°C, and the pressure in the reduction furnace is 0.8Mpa. When the temperature of the surface of the silicon core reaches the conditions for the reaction of SiHCl ₃ and H ₂ , the mixed gas begins to undergo a reduction reaction, and the reacted silicon will be deposited on the silicon core, and the temperature of the inner wall of the bell jar of the polysilicon reduction furnace can be found by measuring the temperature with a temperature probe Always below 475°C;

(5) The exhaust gas after the reaction is discharged through the chassis outlet pipe 6, and the temperature of the exhaust gas is controlled at 330°C±20°C. When the diameter of the silicon core grows to more than 200mm, stop the power supply, and wait until the silicon core cools down, take out the silicon core, and pass It is estimated that the energy saving is about 17%.

Embodiment 3: Operation process 3 of the novel polysilicon reduction furnace:

(1) First turn on the chassis air intake control device 11 and the chassis exhaust control device 19;

(2) Next, cooling water is introduced into the body of the reduction furnace and the chassis of the reduction furnace at the same time, and the liquid trichlorosilane is passed into the side wall of the inner tank of the polysilicon reduction furnace through the liquid trichlorosilane inlet pipe 15 on the side wall of the inner tank. The width of the gap between the inner wall of the liner and the outer wall of the liner is 50 mm, and the distance between the bottom plate 22 and the top plate 23 is 300 mm;

(3) Mix the purified SiHCl ₃ and H ₂ in a certain proportion, and then pass the mixed gas into the polysilicon reduction furnace from the chassis intake pipe 5;

(4) Start the power supply system of the reduction furnace to heat the silicon core, and keep the temperature of the silicon core at 1150°C, and the pressure in the reduction furnace is 0.8Mpa. When the temperature of the surface of the silicon core reaches the conditions for the reaction of SiHCl ₃ and H ₂ , the mixed gas begins to undergo a reduction reaction, and the reacted silicon will be deposited on the silicon core, and the temperature of the inner wall of the bell jar of the polysilicon reduction furnace can be found by measuring the temperature with a temperature probe Always below 400°C;

(5) The exhaust gas after the reaction is discharged through the chassis outlet pipe 6, and the temperature of the exhaust gas is controlled at 320 ° C ± 20. When the diameter of the silicon core grows to more than 200 mm, stop the power supply, and wait until the silicon core cools down, take out the silicon core, and pass It is estimated that the energy saving is about 18%.

The above examples are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be determined by the claims.

Claims (4)

1. An energy-saving polysilicon reduction furnace with a double-layer inner tank, which is characterized in that the inner tank of the polysilicon reduction furnace includes a two-layer structure of an inner wall (20) and an outer wall (21), and the inner wall (20) and the outer wall (21). The gap communicates with the area between the top bottom plate (22) and the top plate (23) of the inner tank, and the connection between the inner wall (20) and the top bottom plate (22) and the connection between the outer wall (21) and the top top plate (23). The width of the gap between (20) and the outer wall (21) is 5mm-50mm, and the distance between the bottom plate (22) and the top plate (23) is 100mm-300mm. 2. The double-layer structure of the liner as claimed in claim 1 is characterized in that the bottom plate at the top of the polysilicon reduction furnace liner is fixedly connected with the inner wall of the liner, the top plate at the top of the liner is fixedly connected with the outer wall of the liner, and the connection method adopts Bolt on. 3. A double-layer structure of an inner tank of an energy-saving polysilicon reduction furnace and its implementation method, which is characterized in that high-purity trichlorosilane liquid is passed between the inner wall and the outer wall of the inner tank of the polysilicon reduction furnace. The heat is radiated to the side of the inner tank, the liquid trichlorosilane is heated and volatilized, and the gas generated by volatilization flows into the area between the top bottom plate and the top plate of the inner tank. 4. An energy-saving polysilicon reduction furnace with a double-layer inner tank structure and its implementation method. The feature is that a temperature probe can be installed in the gap between the inner wall and the outer wall of the inner tank if required during production. the

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