Granular silicon production system

Abstract

The utility model provides a granular silicon production system which comprises a cold hydrogenation device, a disproportionation reactor, a seed crystal reactor and a heterogeneous deposition reactor, an inlet of the cold hydrogenation device is used for receiving hydrogen, silicon powder and carbon tetrachloride, an outlet of the cold hydrogenation device is connected with an inlet of the disproportionation reactor, and a silane outlet of the disproportionation reactor is connected with an inlet of the seed crystal reactor and an inlet of the heterogeneous deposition reactor. A dichlorosilane outlet of the disproportionation reactor is connected with an inlet of the seed crystal reactor; a seed crystal outlet of the seed crystal reactor is connected with an inlet of the heterogeneous deposition reactor, and the inlet of the heterogeneous deposition reactor further receives hydrogen. According to the utility model, particle silicon seed crystals can be continuously produced on line, and secondary pollution of the seed crystals is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of polysilicon preparation and relates to a granular silicon production system. Background Art

[0002] Polysilicon (i.e. silicon material) is a non-metallic material that uses industrial silicon as raw material and is purified through a series of physical and chemical reactions to reach a certain purity. The silicon content is above 99.9999%. In the photovoltaic field, polysilicon is processed into silicon wafers, batteries, and modules, and ultimately used in photovoltaic power generation systems. Crystalline silicon modules account for about 97.5% of photovoltaic installations, and the rest are thin-film modules, etc. Therefore, polysilicon is an important upstream of the photovoltaic industry.

[0003] At present, the mainstream polysilicon production technologies are the modified Siemens process using trichlorosilane as raw material and the fluidized bed process using silane gas as raw material. For the Siemens process, the emergence of tail gas recovery system has improved the material utilization rate, the cold hydrogenation process has replaced the hot hydrogenation process to significantly reduce energy consumption, and multiple pairs of rods and large diameter reduction furnaces have effectively reduced the power consumption of the reduction furnace. Under the main goal of reducing costs and increasing efficiency, technological changes are the key to affecting the competitiveness of enterprises. At present, after the successful mass production of the silane fluidized bed method with the advantage of low power consumption, its development potential is gradually being verified by the industry.

[0004] The silane fluidized bed method refers to a technical route that utilizes the thermal decomposition of monosilane (SiH4) in a fluidized bed reactor. Specifically, high-purity seed crystals (about 0.2-0.6 mm in diameter) as seeds are added from the top of the fluidized bed reactor and piled up to form a bed of seed crystal particles. Silane and hydrogen are introduced from the bottom of the reactor to fluidize the bed. Under the action of an external heater, silane is cracked and deposited on the surface of the seed crystals. The seed crystal particles are continuously produced epitaxially until sufficient weight of granular silicon settles to the bottom of the reactor and is discharged. During the production process, solid reactants move from top to bottom, and gaseous reactants flow from bottom to top, thereby achieving uninterrupted continuous production.

[0005] In the process of producing granular silicon by the silane fluidized bed method, the reaction seeds used are fine granular silicon products screened out from the granular silicon products. The seeds for granular silicon production are not produced online continuously. At the same time, when fine granular silicon products are screened out from the granular silicon products, the possibility of the seeds being contaminated by impurities increases, resulting in the problem of unstable quality. Utility Model Content

[0006] In order to solve the above problems of the prior art, the utility model provides a granular silicon production system, which can continuously produce granular silicon seeds online and avoid secondary contamination of the seeds.

[0007] The utility model is realized by the following technical solutions:

[0008] A granular silicon production system comprises a cold hydrogenation device, a disproportionation reactor, a seed reactor and a heterogeneous deposition reactor; the inlet of the cold hydrogenation device is used to receive hydrogen, silicon powder and carbon tetrachloride, the outlet of the cold hydrogenation device is connected to the inlet of the disproportionation reactor, the silane outlet of the disproportionation reactor is respectively connected to the inlet of the seed reactor and the inlet of the heterogeneous deposition reactor, the dichlorodihydrosilane outlet of the disproportionation reactor is connected to the inlet of the seed reactor; the seed outlet of the seed reactor is connected to the inlet of the heterogeneous deposition reactor, and the inlet of the heterogeneous deposition reactor also receives hydrogen.

[0009] Preferably, the granular silicon production system further comprises a first distillation device; the outlet of the cold hydrogenation device is connected to the inlet of the first distillation device, and the chlorosilane outlet of the first distillation device is connected to the inlet of the disproportionation reactor.

[0010] Furthermore, the silicon tetrachloride outlet of the first distillation device is connected to the inlet of the cold hydrogenation device.

[0011] Preferably, the granular silicon production system further comprises a second distillation device; the silane outlet of the disproportionation reactor is connected to the inlet of the second distillation device, and the silane gas outlet of the second distillation device is respectively connected to the inlet of the seed reactor and the inlet of the heterogeneous deposition reactor.

[0012] Preferably, the granular silicon production system further comprises a third distillation device; the dichlorosilane outlet of the disproportionation reactor is connected to the inlet of the third distillation device; and the dichlorosilane outlet of the third distillation device is connected to the inlet of the seed reactor.

[0013] Preferably, the granular silicon production system further comprises a first purification device, the gas outlet of the heterogeneous deposition reactor is connected to the inlet of the first purification device, and the hydrogen outlet of the first purification device is respectively connected to the inlet of the heterogeneous deposition reactor and the inlet of the cold hydrogenation device.

[0014] Furthermore, the granular silicon production system also includes a second purification device, the silicon granule outlet of the heterogeneous deposition reactor is connected to the inlet of the second purification device, and the two solid outlets of the second purification device are outlets for granular silicon and nano silicon, respectively.

[0015] Furthermore, the gas outlet of the second purification device is connected to the inlet of the first purification device.

[0016] Preferably, the silicon tetrachloride outlet of the disproportionation reactor is connected to the inlet of the cold hydrogenation device.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] The granular silicon production system of the utility model uses silicon powder, silicon tetrachloride and hydrogen as raw materials, performs a hydrogenation reaction in a cold hydrogenation device to obtain trichlorosilane; trichlorosilane performs a one-step disproportionation reaction in a disproportionation reactor, and separates the reaction products to obtain dichlorosilane, silicon tetrachloride and silane respectively; silane reacts with dichlorosilane in a seed reactor to obtain a seed; silane reacts with hydrogen in a heterogeneous deposition reactor to generate silicon, and the silicon is deposited on the seed to obtain coarse granular silicon. The utility model obtains dichlorosilane, silicon tetrachloride and silane through a one-step disproportionation reaction of trichlorosilane, reacts part of the silane with dichlorosilane to provide seeds for the heterogeneous deposition reactor. Compared with taking seeds from silicon granule products, the method of the utility model can continuously produce granular silicon seeds online, avoid secondary pollution of seeds, solve the problem of unstable seed quality, and improve the production efficiency of granular silicon production equipment.

[0019] Furthermore, the utility model is provided with three distillation devices, which are respectively used for purifying trichlorosilane, silane and dichlorosilane, so as to provide high-purity raw gas for the disproportionation reactor, seed reactor and heterogeneous deposition reactor, thereby improving the purity of the product.

[0020] Furthermore, the utility model is provided with a first purification device for purifying the gas coming out of the heterogeneous deposition reactor, removing the hydrogen from silane and microsilicon powder and returning it to the heterogeneous deposition reactor and the cold hydrogenation device for recycling, which can improve the utilization rate of raw materials.

[0021] Furthermore, during the production of granular silicon by the silane fluidized bed method, hydrogen is attached to the inside of the granular silicon product in the form of dangling bonds, which is usually referred to as dissolved hydrogen. The dissolved hydrogen will cause hydrogen jumps in the downstream single crystal pulling process, affecting the continuity and stability of silicon single crystal pulling. At the same time, a large amount of microsilicon powder will be contaminated on the surface of the granular silicon, and the surface is prone to adsorb impurities, reducing product quality. For this reason, the utility model is provided with a second purification device for purifying the granular silicon product coming out of the heterogeneous deposition reactor, removing the microsilicon powder on the surface of the granular silicon and the hydrogen coated in the granular silicon product, which can effectively reduce the residual hydrogen concentration of the granular silicon and the microsilicon powder content in the granular silicon, thereby further improving product quality.

[0022] Furthermore, the utility model connects the silicon tetrachloride outlet of the first distillation device with the inlet of the cold hydrogenation device, and connects the silicon tetrachloride outlet of the disproportionation reactor with the inlet of the cold hydrogenation device, so that the separated silicon tetrachloride is returned to the cold hydrogenation device for recycling, thereby improving the utilization efficiency of raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural schematic diagram of a granular silicon production system in a specific embodiment of the utility model.

[0025] Among them: 1 is a cold hydrogenation device, 2 is a first distillation device, 3 is a disproportionation reactor, 4 is a second distillation device, 5 is a third distillation device, 6 is a seed reactor, 7 is a heterogeneous deposition reactor, 8 is a first purification device, and 9 is a second purification device. DETAILED DESCRIPTION

[0026] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0027] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0028] It should be noted that the terms "include" and "have" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the utility model. Changes or adjustments in their relative relationships should also be regarded as the scope of the utility model without substantially changing the technical content.

[0029] The granular silicon production system described in the utility model comprises a cold hydrogenation device 1, a disproportionation reactor 3, a seed reactor 6 and a heterogeneous deposition reactor 7; the inlet of the cold hydrogenation device 1 is used to receive hydrogen, silicon powder and carbon tetrachloride, the outlet of the cold hydrogenation device 1 is connected to the inlet of the disproportionation reactor 3, the silane outlet of the disproportionation reactor 3 is respectively connected to the inlet of the seed reactor 6 and the inlet of the heterogeneous deposition reactor 7, the dichlorosilane outlet of the disproportionation reactor 3 is connected to the inlet of the seed reactor 6; the seed outlet of the seed reactor 6 is connected to the inlet of the heterogeneous deposition reactor 7, and the inlet of the heterogeneous deposition reactor 7 also receives hydrogen.

[0030] In some specific embodiments of the utility model, the granular silicon production system also includes a first distillation device 2, a second distillation device 4 and a third distillation device 5; the outlet of the cold hydrogenation device 1 is connected to the inlet of the first distillation device 2, the chlorosilane outlet of the first distillation device 2 is connected to the inlet of the disproportionation reactor 3, the silane outlet of the disproportionation reactor 3 is connected to the inlet of the second distillation device 4, and the dichlorosilane outlet of the disproportionation reactor 3 is connected to the inlet of the third distillation device 5; the silane gas outlet of the second distillation device 4 is respectively connected to the inlet of the seed reactor 6 and the inlet of the heterogeneous deposition reactor 7, and the dichlorosilane outlet of the third distillation device 5 is connected to the inlet of the seed reactor 6.

[0031] In the cold hydrogenation device 1, hydrogenation reaction is carried out with hydrogen, silicon powder and carbon tetrachloride as raw materials to obtain trichlorosilane; the components of trichlorosilane include dichlorodihydrosilane, trichlorosilane and silicon tetrachloride. The first distillation device 2 is used to purify and separate the trichlorosilane from the cold hydrogenation device 1, and purify and separate it into a mixture of dichlorodihydrosilane and trichlorosilane and silicon tetrachloride. In the disproportionation reactor 3, the mixture of dichlorodihydrosilane and trichlorosilane from the first distillation device 2 is subjected to disproportionation reaction, and trichlorosilane reacts to produce dichlorodihydrosilane and silane, which are separated to obtain dichlorodihydrosilane, silane and silicon tetrachloride respectively. The second distillation device 4 is used to purify silane from the disproportionation reactor 3 to obtain silane gas; the third distillation device 5 is used to purify dichlorodihydrosilane from the disproportionation reactor 3 to obtain dichlorodihydrosilane. In the seed reactor 6, silane gas reacts with dichlorodihydrosilane to obtain polysilicon seeds. In the heterogeneous deposition reactor 7, silane gas reacts with hydrogen to generate silicon, which is deposited on the seed crystal to form granular silicon.

[0032] In some specific embodiments of the present invention, the silicon tetrachloride outlet of the first distillation device 2 is connected to the inlet of the cold hydrogenation device 1, so that the silicon tetrachloride separated by the first distillation device 2 is returned to the cold hydrogenation device 1 for recycling.

[0033] In some specific embodiments of the present invention, the silicon tetrachloride outlet of the disproportionation reactor 3 is connected to the inlet of the cold hydrogenation device 1, so that the silicon tetrachloride separated from the disproportionation reactor 3 is returned to the cold hydrogenation device 1 for recycling.

[0034] In some specific embodiments of the utility model, the granular silicon production system further includes a first purification device 8, the gas outlet of the heterogeneous deposition reactor 7 is connected to the inlet of the first purification device 8, and the hydrogen outlet of the first purification device 8 is respectively connected to the inlet of the heterogeneous deposition reactor 7 and the inlet of the cold hydrogenation device 1. The first purification device 8 is used to purify the hydrogen from the heterogeneous deposition reactor 7, and the purified hydrogen returns to the heterogeneous deposition reactor 7 and the cold hydrogenation device 1 to achieve the recycling of hydrogen; the silicon powder obtained by hydrogen purification forms a nano-silicon product.

[0035] In some specific embodiments of the utility model, the granular silicon production system further includes a second purification device 9, the silicon granule outlet of the heterogeneous deposition reactor 7 is connected to the inlet of the second purification device 9, the gas outlet of the second purification device 9 is connected to the inlet of the first purification device 8, and the two solid outlets of the second purification device 9 are outlets for granular silicon and nano silicon, respectively. The second purification device 9 mainly includes heating, degassing, replacement, screening, cleaning, and drying processes, which are used to purify the granular silicon from the heterogeneous deposition reactor 7, remove silicon powder on the surface of silicon particles and hydrogen in silicon particles, and obtain high-purity granular silicon products and nano silicon products. The hydrogen from the second purification device 9 enters the first purification device 8 for purification and then recycling.

[0036] Based on the above-mentioned granular silicon production system, the granular silicon production method described in the utility model includes the following steps:

[0037] Silicon powder, silicon tetrachloride and hydrogen are used as raw materials, and a hydrogenation reaction is carried out in a cold hydrogenation device 1 to obtain trichlorosilane;

[0038] The trichlorosilane from the cold hydrogenation device 1 is subjected to a disproportionation reaction in the disproportionation reactor 3, and the reaction products are separated to obtain dichlorosilane, silicon tetrachloride and silane respectively;

[0039] The silane and dichlorosilane from the disproportionation reactor 3 are reacted in the seed reactor 6 to obtain seed crystals;

[0040] Using hydrogen, silane from the disproportionation reactor 3 and seeds from the seed reactor 6 as raw materials, a heterogeneous deposition reaction is carried out in the heterogeneous deposition reactor 7 to obtain granular silicon.

[0041] When the granular silicon production system includes a first distillation device 2, a second distillation device 4 and a third distillation device 5, the granular silicon production method specifically includes the following steps:

[0042] Silicon powder, silicon tetrachloride and hydrogen are used as raw materials, and a hydrogenation reaction is carried out in a cold hydrogenation device 1 to obtain trichlorosilane;

[0043] The trichlorosilane from the cold hydrogenation device 1 is purified and separated into a mixture of dichlorosilane and trichlorosilane and silicon tetrachloride by a first rectification device 2;

[0044] The mixture of dichlorosilane and trichlorosilane from the first distillation device 2 is subjected to a disproportionation reaction in a disproportionation reactor 3, and the reaction products are separated to obtain dichlorosilane, silicon tetrachloride and silane respectively;

[0045] Purifying the silane from the disproportionation reactor 3 through the second distillation device 4 to obtain silane gas;

[0046] Purifying the dichlorosilane from the disproportionation reactor 3 through the third distillation device 5 to obtain dichlorosilane;

[0047] The silane gas purified by the second distillation device 4 and the dichlorodihydrosilane purified by the third distillation device 5 are reacted in a seed crystal reactor 6 to obtain seed crystals;

[0048] The silane gas purified by the second distillation device 4 is reacted with the seed crystals and hydrogen from the seed crystal reactor 6 as raw materials in the heterogeneous deposition reactor 7 to obtain granular silicon.

[0049] In some specific embodiments of the present invention, the granular silicon production method further comprises: returning the silicon tetrachloride from the first distillation device 2 and the silicon tetrachloride from the disproportionation reactor 3 to the cold hydrogenation device 1 .

[0050] In some specific embodiments of the present invention, the granular silicon production method further includes at least one of the following steps:

[0051] Purifying and separating the granular silicon from the heterogeneous deposition reactor 7 through the second purification device 9 to obtain a granular silicon product and a nano-silicon product;

[0052] The gas from the heterogeneous deposition reactor 7 is purified, separated and pressurized by the first purification device 8 and then returned to the heterogeneous deposition reactor 7 and the cold hydrogenation device 1 .

[0053] Example 1

[0054] The granular silicon production system described in this embodiment includes a cold hydrogenation device 1, a first distillation device 2, a disproportionation reactor 3, a second distillation device 4, a third distillation device 5, a seed reactor 6, a heterogeneous deposition reactor 7, a first purification device 8 and a second purification device 9; the inlet of the cold hydrogenation device 1 is used to receive hydrogen, silicon powder and carbon tetrachloride, the outlet of the cold hydrogenation device 1 is connected to the inlet of the first distillation device 2, the chlorosilane outlet of the first distillation device 2 is connected to the inlet of the disproportionation reactor 3, the silicon tetrachloride outlet of the first distillation device 2 is connected to the inlet of the cold hydrogenation device 1, the silane outlet of the disproportionation reactor 3 is connected to the inlet of the second distillation device 4, the dichlorodihydrosilane outlet of the disproportionation reactor 3 is connected to the inlet of the third distillation device 5, and the silicon tetrachloride outlet of the disproportionation reactor 3 is connected to the inlet of the cold hydrogenation device 1 ; The silane gas outlet of the second distillation device 4 is connected to the inlet of the seed reactor 6 and the inlet of the heterogeneous deposition reactor 7 respectively; the dichlorodihydrosilane outlet of the third distillation device 5 is connected to the inlet of the seed reactor 6; the seed outlet of the seed reactor 6 is connected to the inlet of the heterogeneous deposition reactor 7, and the inlet of the heterogeneous deposition reactor 7 also receives hydrogen; the gas outlet of the heterogeneous deposition reactor 7 is connected to the inlet of the first purification device 8, and the hydrogen outlet of the first purification device 8 is connected to the inlet of the heterogeneous deposition reactor 7 and the inlet of the cold hydrogenation device 1 respectively; the silicon particle outlet of the heterogeneous deposition reactor 7 is connected to the inlet of the second purification device 9, and the gas outlet of the second purification device 9 is connected to the inlet of the first purification device 8, and the two solid outlets of the second purification device 9 are outlets for granular silicon and nano silicon, respectively.

[0055] The method for producing granular silicon in this embodiment comprises the following steps:

[0056] Step 1: Using silicon powder, silicon tetrachloride and hydrogen as raw materials, a hydrogenation reaction is carried out in a cold hydrogenation device 1 to obtain crude trichlorosilane; wherein the crude trichlorosilane comprises dichlorodihydrosilane, trichlorosilane and silicon tetrachloride.

[0057] Step 2: Purify and separate the crude trichlorosilane into a mixture of dichlorosilane and trichlorosilane and silicon tetrachloride through a first distillation device 2; the separated silicon tetrachloride returns to the cold hydrogenation device 1, and the mixture of dichlorosilane and trichlorosilane enters the disproportionation reactor 3, and after reaction, separates and purifies to obtain crude dichlorosilane, silicon tetrachloride and crude silane.

[0058] Step 3: Purify and separate the crude silane from the disproportionation reactor 3 through the second distillation device 4 to obtain high-purity silane gas. Purify and separate the crude dichlorosilane from the disproportionation reactor 3 through the third distillation device 5 to obtain high-purity dichlorosilane.

[0059] Step 4: High-purity silane gas from the second distillation device 4 and high-purity dichlorosilane from the third distillation device 5 are introduced into the seed crystal reactor 6 to react and generate polysilicon seed crystals.

[0060] Step five, the high-purity silane gas from the second distillation device 4, the seeds from the seed reactor 6 and the hydrogen circulating in the heterogeneous deposition reactor 7 undergo a heterogeneous deposition reaction in the heterogeneous deposition reactor 7, and the silicon decomposed from the silane gas is deposited on the surface of the seed to form a coarse granular silicon product.

[0061] Step 6: More than 95% of the equivalent diameters of the granular silicon obtained by the reaction in the heterogeneous deposition reactor 7 are within the range of 150-2000 microns. The coarse granular silicon is treated in the second purification device 9 to remove silicon powder, thereby obtaining a granular silicon product and a nano-silicon product after the silicon powder is removed. The second purification device 9 can remove the silicon powder adsorbed on the surface of the granular silicon and the hydrogen coated by the silicon powder, so that the dissolved hydrogen in the granular silicon is reduced to 5ppma-50ppma.

[0062] Step seven, purifying and separating the gas from the heterogeneous deposition reactor 7 through the first purification device 8 and pressurizing it to form high-purity hydrogen gas, which is then returned to the heterogeneous deposition reactor 7 and the cold hydrogenation device 1 for recycling.

[0063] The utility model can continuously produce granular silicon seeds online, avoid secondary contamination of the seeds, improve the raw material utilization rate of the silane fluidized bed device, and improve the production efficiency of the product; the granular silicon and hydrogen are purified by a purification device to remove the hydrogen coated in the silicon particles, and the granular silicon product after the silicon powder is removed is obtained by processing, which can effectively reduce the residual hydrogen concentration of the granular silicon and the microsilicon powder in the granular silicon, thereby further improving the product quality and stability.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A granular silicon production system, characterized in that: The invention comprises a cold hydrogenation device (1), a disproportionation reactor (3), a seed reactor (6) and a heterogeneous deposition reactor (7); the inlet of the cold hydrogenation device (1) is used to receive hydrogen, silicon powder and carbon tetrachloride, the outlet of the cold hydrogenation device (1) is connected to the inlet of the disproportionation reactor (3), the silane outlet of the disproportionation reactor (3) is connected to the inlet of the seed reactor (6) and the inlet of the heterogeneous deposition reactor (7) respectively, the dichlorosilane outlet of the disproportionation reactor (3) is connected to the inlet of the seed reactor (6); the seed outlet of the seed reactor (6) is connected to the inlet of the heterogeneous deposition reactor (7), and the inlet of the heterogeneous deposition reactor (7) also receives hydrogen.

2. The granular silicon production system according to claim 1, characterized in that: The granular silicon production system further comprises a first distillation device (2); the outlet of the cold hydrogenation device (1) is connected to the inlet of the first distillation device (2), and the chlorosilane outlet of the first distillation device (2) is connected to the inlet of the disproportionation reactor (3).

3. The granular silicon production system according to claim 2, characterized in that: The silicon tetrachloride outlet of the first distillation device (2) is connected to the inlet of the cold hydrogenation device (1).

4. The granular silicon production system according to claim 1, characterized in that: The granular silicon production system also includes a second distillation device (4); the silane outlet of the disproportionation reactor (3) is connected to the inlet of the second distillation device (4), and the silane gas outlet of the second distillation device (4) is respectively connected to the inlet of the seed reactor (6) and the inlet of the heterogeneous deposition reactor (7).

5. The granular silicon production system according to claim 1, characterized in that: The granular silicon production system further comprises a third distillation device (5); the dichlorosilane outlet of the disproportionation reactor (3) is connected to the inlet of the third distillation device (5); and the dichlorosilane outlet of the third distillation device (5) is connected to the inlet of the seed reactor (6).

6. The granular silicon production system according to claim 1, characterized in that: The granular silicon production system also includes a first purification device (8), the gas outlet of the heterogeneous deposition reactor (7) is connected to the inlet of the first purification device (8), and the hydrogen outlet of the first purification device (8) is respectively connected to the inlet of the heterogeneous deposition reactor (7) and the inlet of the cold hydrogenation device (1).

7. The granular silicon production system according to claim 6, characterized in that: The granular silicon production system further comprises a second purification device (9), the silicon granule outlet of the heterogeneous deposition reactor (7) is connected to the inlet of the second purification device (9), and the two solid outlets of the second purification device (9) are outlets for granular silicon and nano silicon, respectively.

8. The granular silicon production system according to claim 7, characterized in that: The gas outlet of the second purification device (9) is connected to the inlet of the first purification device (8).

9. The granular silicon production system according to claim 1, characterized in that: The silicon tetrachloride outlet of the disproportionation reactor (3) is connected to the inlet of the cold hydrogenation device (1).

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