A granular polysilicon production system

Abstract

The utility model discloses a granular polycrystal silicon production system relates to polycrystal silicon production technical field, aims at solving the problem of the gas bubble that the polycrystal silicon production in prior art produces in the process of ascending in fluidized bed, reduces the heat transfer, mass transfer efficiency of fluidized bed and the deposition speed and unit output of polycrystal silicon, and it includes the first pipeline and the second pipeline for discharging reaction tail gas that are connected at the top of fluidized bed reactor, and the first pipeline is communicated with seed crystal jar, granular polycrystal silicon jar respectively, the bottom of fluidized bed reactor is equipped with the raw material gas inlet pipe for inputting the silicon-containing reaction gas and the unloading pipeline for discharging polycrystal silicon product. The utility model adds the large diameter granular polycrystal silicon in the seed crystal, mixes and then adds the fluidized bed, owing to the large diameter granular polycrystal silicon particle size is larger and falls in the fluidized bed fast, in the falling process, and the bubble that forms in the fluidized bed contacts, makes the bubble break, destroys the bubble and continues to grow, effectively realizes the effect of reducing the bubble.

Description

Technical Field

[0001] This utility model relates to a granular polycrystalline silicon production system, belonging to the field of polycrystalline silicon production technology. Background Technology

[0002] Polycrystalline silicon is a fundamental raw material for integrated circuits and photovoltaic cells. Generally, polycrystalline silicon is produced through chemical vapor deposition (CVD). Currently, the mainstream polycrystalline silicon production processes are the modified Siemens process and the fluidized bed process. The fluidized bed process uses a suitable silicon-containing gas as a raw material. This gas, along with hydrogen, is introduced into a fluidized bed reactor. In the reactor, at temperatures of 500–1100°C, the silicon-containing gas is reduced or decomposed into elemental silicon, which is deposited on silicon seed particles with a diameter of 300–800 micrometers. The silicon seed particles gradually grow to form silicon particles of 2000–4000 micrometers and are discharged from the fluidized bed reactor, forming granular polycrystalline silicon products. Suitable silicon-containing gases include silanes, trichlorosilanes, and dichlorosilanes.

[0003] In a fluidized bed reactor, gas enters the reactor from the bottom gas distributor through the fluidized bed. Inside the fluidized bed, the gas gradually forms bubbles as it rises and grows larger. The formation of bubbles reduces the heat and mass transfer efficiency of the fluidized bed, as well as the deposition rate and yield of polysilicon. Furthermore, the bubbles in the fluidized bed will naturally burst after growing to a certain size, and the bursting of large bubbles also has an adverse effect on the stable operation of the fluidized bed.

[0004] Currently, improvements to gas distributors or the use of external forces such as vibration, magnetic fields, or ultrasound are employed to reduce or eliminate bubbles. However, this increases costs and may not be suitable for existing granular polysilicon production equipment. Therefore, it is necessary to develop new and easily implemented methods and systems to reduce and eliminate bubbles for granular polysilicon production. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a granular polycrystalline silicon production system. Large-diameter granular polycrystalline silicon is added to the seed crystal. After the large-diameter granular polycrystalline silicon and the seed crystal are added to the fluidized bed, the large-diameter granular polycrystalline silicon falls rapidly in the fluidized bed due to its large diameter. During the falling process, it comes into contact with the bubbles formed in the fluidized bed, breaking the bubbles and preventing them from continuing to grow, thus effectively achieving the effect of bubble breaking.

[0006] To achieve the above objectives, this utility model employs the following technical solution: On one hand, this utility model provides a granular polycrystalline silicon production system, including a fluidized bed reactor. The top of the fluidized bed reactor is connected to a first pipeline and a second pipeline. The end of the first pipeline away from the fluidized bed reactor is provided with a first branch and a second branch. The first branch is connected to a seed crystal tank, in which granular crystals are placed. The second branch is connected to a granular polycrystalline silicon tank, in which granular polycrystalline silicon is placed. The second pipeline is used to discharge reaction tail gas. The fluidized bed reactor is equipped with a raw material inlet pipe and a discharge pipe at the bottom. The raw material inlet pipe is used to input silicon-containing reaction gas into the fluidized bed reactor, and the discharge pipe is used to discharge polycrystalline silicon products.

[0007] Furthermore, the fluidized bed reactor includes a reaction chamber and a gas chamber arranged sequentially from top to bottom, and a gas distribution plate is provided between the reaction chamber and the gas chamber.

[0008] Furthermore, valves are installed on the first branch, the second branch, the second pipeline, the raw material inlet pipe, and the discharge pipeline.

[0009] Furthermore, the first pipeline is used to mix the seed crystal and granular polycrystalline silicon to obtain a mixed solid raw material, wherein the mass percentage of granular polycrystalline silicon in the mixed solid raw material is 0.1~15%.

[0010] Furthermore, the mass percentage of granular polycrystalline silicon in the mixed solid raw material is 0.5-5%.

[0011] Furthermore, the mass percentage of granular polycrystalline silicon in the mixed solid raw material is 1-2%.

[0012] Furthermore, the particle size range of the granular polycrystalline silicon is 1500~4500μm.

[0013] Furthermore, the particle size range of the granular polycrystalline silicon is 2000~3500μm.

[0014] On the other hand, this utility model also provides a method for producing granular polycrystalline silicon, the method being implemented by a granular polycrystalline silicon production system as described in any of the preceding claims, comprising: Seed crystals and granular polycrystalline silicon are respectively transported from seed crystal tank and granular polycrystalline silicon tank to the first pipeline. In the first pipeline, the seed crystals and granular polycrystalline silicon are mixed to obtain a mixed solid raw material, which then enters the fluidized bed reactor. Simultaneously, silicon-containing reaction gas is transported to the fluidized bed reactor through the raw material inlet pipe; The silicon-containing reactive gas decomposes and deposits on the surface of the mixed solid raw material to form a polycrystalline silicon product and generate a reaction tail gas. The polycrystalline silicon product is discharged through the feeding pipeline, and the reaction tail gas is discharged through the second pipeline.

[0015] Furthermore, the silicon-containing reactive gas includes hydrogen and silane.

[0016] Compared with the prior art, the beneficial effects achieved by this utility model are as follows: This invention relates to a method in polycrystalline silicon production where large-diameter granular polycrystalline silicon is incorporated into the seed crystal. When both are added to a fluidized bed, the larger diameter of the granular polycrystalline silicon causes it to fall rapidly. During this fall, it comes into contact with bubbles formed in the fluidized bed, breaking them and preventing further bubble growth, thus reducing the generation of silicon micropowder. This solves the problem of bubble formation during the upward flow of gas in the fluidized bed during polycrystalline silicon production, effectively improving the heat and mass transfer efficiency of the fluidized bed, and increasing the deposition rate and yield of polycrystalline silicon per unit area. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a granular polycrystalline silicon production system in one embodiment of the present invention; In the diagram: 1-fluidized bed reactor, 101-reaction chamber, 102-gas chamber, 103-gas distribution plate, 2-first pipeline, 201-first branch, 202-second branch, 3-second pipeline, 4-raw material inlet pipe, 5-feeding pipeline, 6-seed crystal tank, 7-granular polycrystalline silicon tank, 8-valve. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention. Example 1

[0019] like Figure 1 As shown in the figure, this utility model embodiment provides a granular polycrystalline silicon production system, including a fluidized bed reactor 1. A first pipeline 2 and a second pipeline 3 are connected to the top of the fluidized bed reactor 1. A first branch 201 and a second branch 202 are provided at the end of the first pipeline 2 furthest from the fluidized bed reactor 1. The first branch 201 is connected to a seed crystal tank 6, and the second branch 202 is connected to a granular polycrystalline silicon tank 7. Seed crystals are placed in the seed crystal tank 6, and granular polycrystalline silicon is placed in the granular polycrystalline silicon tank 7. The seed crystals and granular polycrystalline silicon are respectively transported to the first pipeline 2 via the first branch 201 and the second branch 202 to mix and form a mixed solid raw material.

[0020] In this embodiment, the granular polycrystalline silicon has a large diameter, ranging from 1500 to 4500 μm, preferably from 2000 to 3500 μm. The mass percentage of granular polycrystalline silicon in the mixed solid raw material is 0.1% to 15%, preferably 0.5% to 5%, and more preferably 1% to 2%.

[0021] The bottom of the fluidized bed reactor 1 is connected to a raw material inlet pipe 4 and a feed line 5. The raw material inlet pipe 4 is used to input silicon-containing reaction gas into the fluidized bed reactor 1. In this embodiment, the silicon-containing reaction gas is a mixture of silane and hydrogen. The feed line 5 is used to output the polycrystalline silicon product prepared by the fluidized reaction.

[0022] The fluidized bed reactor 1 has a reaction chamber 101 and a gas chamber 102 arranged sequentially from top to bottom inside, and the reaction chamber 101 and the gas chamber 102 are separated by a gas distribution plate 103.

[0023] In some embodiments, valves are provided on the first branch 201, the second branch 202, the second pipeline 3, the raw material inlet pipe 4, and the discharge pipeline 5. The valves 8 can control the start and stop of the corresponding pipelines. Example 2

[0024] Based on Example 1, this example also provides a method for producing granular polycrystalline silicon, which specifically includes the following steps: Seed crystals and granular polycrystalline silicon are respectively transported from seed crystal tank 6 and granular polycrystalline silicon tank 7 to the first pipeline 2. In the first pipeline 2, the seed crystals and granular polycrystalline silicon are mixed to obtain a mixed solid raw material, which then enters the reaction chamber of fluidized bed reactor 1.

[0025] Meanwhile, silicon-containing reaction gas is transported from the raw material inlet pipe 4 to the gas chamber 102 of the fluidized bed reactor 1, and then enters the reaction chamber 101 of the fluidized bed reactor 1 through the gas distribution plate 103.

[0026] The silicon-containing reactive gas decomposes and deposits on the surface of the mixed solid raw materials to form polycrystalline silicon products and generate reaction tail gas. The polycrystalline silicon products are discharged through the feeding pipeline 5, and the reaction tail gas is discharged through the second pipeline 3.

[0027] Bubbles begin to form and grow gradually in the lower part of the fluidized bed. Due to the large weight of the large-diameter granular polycrystalline silicon, it falls rapidly after being added to the fluidized bed reactor 1 from the top. This causes the bubbles to be continuously broken up by the large-diameter granular polycrystalline silicon added to the fluidized bed reactor 1 from the top during the production and growth process.

[0028] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A granular polycrystalline silicon production system, characterized in that, The system includes a fluidized bed reactor, with a first pipeline and a second pipeline connected to the top of the fluidized bed reactor. The first pipeline has a first branch and a second branch at the end away from the fluidized bed reactor. The first branch is connected to a seed crystal tank, in which granular crystals are placed. The second branch is connected to a granular polycrystalline silicon tank, in which granular polycrystalline silicon is placed. The second pipeline is used to discharge reaction tail gas. The fluidized bed reactor is equipped with a raw material inlet pipe and a discharge pipe at the bottom. The raw material inlet pipe is used to input silicon-containing reaction gas into the fluidized bed reactor, and the discharge pipe is used to discharge polycrystalline silicon products.

2. The granular polycrystalline silicon production system according to claim 1, characterized in that, The fluidized bed reactor includes a reaction chamber and a gas chamber arranged sequentially from top to bottom, and a gas distribution plate is provided between the reaction chamber and the gas chamber.

3. The granular polycrystalline silicon production system according to claim 1, characterized in that, Valves are installed on the first branch, the second branch, the second pipeline, the raw material inlet pipe, and the discharge pipeline.

4. The granular polycrystalline silicon production system according to claim 1, characterized in that, The particle size range of the granular polycrystalline silicon is 1500~4500μm.

5. The granular polycrystalline silicon production system according to claim 4, characterized in that, The particle size range of the granular polycrystalline silicon is 2000~3500μm.

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