A trichlorosilane purification system in the polysilicon production process

Abstract

This invention relates to the field of polysilicon production equipment technology, and particularly to a trichlorosilane purification system in the polysilicon production process. The system comprises: a primary crude distillation column connected to a cold hydrogenation initial separation column; a low-boiling-point recovery column connected to the primary crude distillation column; a secondary crude distillation column connected to the primary crude distillation column; a primary rectification column connected to the secondary crude distillation column; a high-boiling-point recovery column connected to the primary rectification column; a secondary rectification column connected to the primary rectification column; a secondary rectification column connected to the primary crude distillation column; a tertiary rectification column connected to the secondary rectification column; the reboiler of the tertiary rectification column connected to the primary rectification column; a light-weight removal column connected to both the low-boiling-point and high-boiling-point recovery columns; a heavy-weight removal column connected to the light-weight removal column; the reboiler of the high-boiling-point recovery column connected to the heavy-weight removal column; the gas phase outlet of the heavy-weight removal column sequentially connected to a gas phase adsorption device and a light-weight separation column; the reflux port of the light-weight separation column connected to the light-weight removal column; and a heavy-weight separation column connected to the light-weight separation column. This invention improves the stability and reliability of the distillation system under high load operation.

Description

Technical Field

[0001] This invention relates to the field of polysilicon production equipment technology, and in particular to a trichlorosilane purification system in the polysilicon production process. Background Technology

[0002] In the improved Siemens process for polysilicon production, the mixture of dichlorosilane, trichlorosilane, and silicon tetrachloride synthesized in the cold hydrogenation step needs to be sent to a distillation system for purification. The distillation system purifies the trichlorosilane through multiple stages to achieve a highly pure, qualified product, which is then sent to the reduction furnace for polysilicon production. In recent years, to reduce investment and operating costs, enhance economies of scale, further conserve energy, and improve economic efficiency, the capacity of polysilicon production plants has been gradually expanding, and the scale of distillation systems has also increased. However, the expansion of the distillation system's scale can affect the precision of distillation column parameter control and the stability of distillation column operation; especially when the distillation system is operating under high load, the precision of distillation column parameter control deteriorates, and operational stability also decreases. When the system fluctuates or the impurity content of the cold hydrogenation feed suddenly increases, impurities accumulate in the distillation system, causing an impact. Because the existing distillation system is a single-line distillation system, the accumulation of impurities in the distillation system will directly affect the quality stability of the output liquid trichlorosilane. This will further lead to poor quality control and frequent quality fluctuations in the subsequent production of polysilicon, which will greatly affect economic benefits. Summary of the Invention

[0003] In view of this, the present invention provides a trichlorosilane purification system in the polysilicon production process, the main purpose of which is to improve the stability and reliability of the distillation system under high load operation, ensure the quality stability of trichlorosilane, and thus reduce the impact on the quality of polysilicon products.

[0004] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0005] The present invention provides a trichlorosilane purification system in the polysilicon production process, comprising: a cold hydrogenation primary separation tower, a primary crude distillation tower, a low-boiling recovery tower, a secondary crude distillation tower, a primary rectification tower, a high-boiling recovery tower, a secondary rectification tower, a tertiary rectification tower, a light component removal tower, a heavy component removal tower, a light component separation tower, and a heavy component separation tower.

[0006] The cold hydrogenation primary separation tower is used to separate and purify the synthesized materials;

[0007] The crude distillation primary column is connected to the cold hydrogenation initial separation column;

[0008] The low-boiling recovery tower is connected to the primary crude distillation tower and is used to separate the reflux product from the primary crude distillation tower.

[0009] The secondary crude distillation column is connected to the primary crude distillation column and is used to separate and purify the bottom product of the primary crude distillation column.

[0010] The primary distillation column is connected to the secondary crude distillation column and is used to deweight the reflux product from the secondary crude distillation column.

[0011] The high-boiling recovery tower is connected to the first-stage distillation tower and is used to degravate the material collected from the bottom of the first-stage distillation tower.

[0012] The secondary distillation column is connected to the primary distillation column and is used to remove light substances from the reflux product of the primary distillation column.

[0013] The secondary distillation column is connected to the primary crude distillation column, and is used to reflux a portion of the material to the primary crude distillation column for purification.

[0014] The third-stage distillation column is connected to the second-stage distillation column and is used to remove weight from the bottom of the second-stage distillation column; the third-stage distillation column can reflux and collect trichlorosilane.

[0015] The reboiler of the three-stage distillation column is connected to the first-stage distillation column, so that part of the material from the reboiler of the three-stage distillation column can be refluxed to the first-stage distillation column for further purification.

[0016] The material inlet of the light-light removal tower is connected to the bottom of the low-boiling recovery tower, and is used to remove light-light materials from the bottom of the low-boiling recovery tower.

[0017] The material inlet of the light-light removal tower is connected to the high-boiling-point recovery tower and is used to remove light-light materials from the reflux of the high-boiling-point recovery tower.

[0018] The reflux outlet of the light-light-removal tower is connected to the low-boiling-point recovery tower;

[0019] The material inlet of the heavy removal tower is connected to the bottom outlet of the light removal tower;

[0020] The high-boiling-point recovery tower is connected to the bottom of the deweighting tower and is used to deweight the material collected from the bottom of the deweighting tower.

[0021] The gas phase outlet of the deweight removal tower is connected to the inlet of the gas phase adsorption device;

[0022] The inlet of the light separation tower is connected to the outlet of the gas phase adsorption device; the reflux outlet of the light separation tower is connected to the light removal tower.

[0023] The heavy separation tower is connected to the bottom of the light separation tower and is used for deweighting the material collected from the bottom of the light separation tower; the heavy separation tower can reflux and collect trichlorosilane.

[0024] Furthermore, it also includes: a disproportionation unit and a hydrogenation disproportionation fractionation tower;

[0025] The anti-disproportionation device is connected to the low-boiling recovery tower;

[0026] The material inlet of the hydrogenation disproportionation fractionation tower is connected to the disproportionation device;

[0027] The material outlet of the hydrogenation disproportionation fractionation tower is connected to the material inlet of the low-boiling recovery tower.

[0028] Furthermore, the crude distillation secondary column has a reflux feed inlet, which is connected to the bottom of the crude distillation primary column;

[0029] The input end of the column bottom pump is connected to the column bottom of the crude distillation secondary column;

[0030] The output end of the bottom pump is connected to the complexation reflux port of the crude distillation secondary column;

[0031] The complexation reflux port of the crude distillation secondary column is located above the reflux feed outlet.

[0032] Furthermore, it also includes: a hydrolysis treatment system;

[0033] The hydrolysis treatment system is connected to the output end of the bottom pump of the tower.

[0034] Furthermore, the crude distillation secondary column is equipped with a siloxane replenishment port, which is located above the reflux outfeed inlet and is used for the input of siloxane.

[0035] Furthermore, the hydrolysis treatment system is connected to the bottom of the high-boiling recovery tower.

[0036] Furthermore, it also includes: a cold hydrogenation system;

[0037] The cold hydrogenation system is connected to the bottom of the cold hydrogenation primary separation tower;

[0038] The cold hydrogenation system is connected to the bottom of the hydrogenation disproportionation fractionation tower.

[0039] Furthermore, a liquid phase adsorption device is connected between the heavy removal tower and the high boiling point recovery tower.

[0040] Furthermore, the adsorbent used in the liquid phase adsorption device is modified activated carbon, adsorption resin, or silica gel.

[0041] The adsorbent used in the gas phase adsorption device is silica-alumina gel, activated carbon, or molecular sieve.

[0042] The adsorbent used in the gas phase adsorption device is different from the adsorbent used in the liquid phase adsorption device.

[0043] Furthermore, the crude distillation secondary column uses siloxane for complexation and impurity removal.

[0044] By employing the above technical solution, the trichlorosilane purification system in the polysilicon production process of the present invention has at least the following advantages:

[0045] It can improve the stability and reliability of the distillation system under high load, ensure the quality stability of trichlorosilane, and thus reduce the impact on the quality of polysilicon products.

[0046] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0047] Figure 1 A schematic diagram of a trichlorosilane purification system in the polycrystalline silicon production process provided by an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of a crude distillation secondary column in a trichlorosilane purification system during polysilicon production, provided as an embodiment of the present invention.

[0049] As shown in the figure:

[0050] 1 is the synthesis feed storage tank; 2 is the cold hydrogenation primary separation tower; 3 is the crude distillation primary tower; 4 is the crude distillation secondary tower; 4-1 is the siloxane replenishment port; 5 is the rectification primary tower; 6 is the rectification secondary tower; 7 is the rectification tertiary tower; 8 is the low-boiling recovery tower; 9 is the disproportionation unit; 10 is the hydrogenation disproportionation fractionation tower; 11 is the high-boiling recovery tower; 12 is the light component removal tower; 13 is the heavy component removal tower; 14 is the light component separation tower; 15 is the heavy component separation tower; 16 is the gas phase adsorption unit; 17 is the liquid phase adsorption unit; 18 is the tower bottom pump. Detailed Implementation

[0051] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0052] like Figure 1As shown in one embodiment of the present invention, a trichlorosilane purification system in a polysilicon production process includes: a cold hydrogenation primary separation tower 2, a crude distillation primary tower 3, a low-boiling-point recovery tower 8, a crude distillation secondary tower 4, a rectification primary tower 5, a high-boiling-point recovery tower 11, a rectification secondary tower 6, a rectification tertiary tower 7, a light-light removal tower 12, a heavy-light removal tower 13, a light separation tower 14, and a heavy separation tower 15. The cold hydrogenation primary separation tower 2, crude distillation primary tower 3, low-boiling-point recovery tower 8, crude distillation secondary tower 4, rectification primary tower 5, high-boiling-point recovery tower 11, rectification secondary tower 6, and rectification tertiary tower 7 constitute the main processing system for purifying trichlorosilane. The light-light removal tower 12, heavy-light removal tower 13, light separation tower 14, and heavy separation tower 15 constitute the secondary processing system for purifying trichlorosilane, mainly processing the residue discharged from the low-boiling-point recovery tower 8 and the high-boiling-point recovery tower 11.

[0053] The cold hydrogenation primary separation tower 2 is used to separate and purify the synthetic material. The synthetic material comes from the cold hydrogenation system. Preferably, the inlet of the cold hydrogenation primary separation tower 2 is connected to the synthetic material storage tank 1 to achieve temporary storage and buffering of the material. The synthetic material sent from the cold hydrogenation system enters the synthetic material storage tank 1, and the material in the synthetic material storage tank 1 is pressurized and transported to the cold hydrogenation primary separation tower 2 by a pump.

[0054] The primary distillation column 3 is connected to the cold hydrogenation primary separation column 2; after separation and purification in the cold hydrogenation primary separation column 2, 99.5% of silicon tetrachloride is returned from the bottom of the cold hydrogenation primary separation column 2 to the cold hydrogenation system; trichlorosilane and dichlorosilane are refluxed from the cold hydrogenation primary separation column 2 to the primary distillation column 3.

[0055] The low-boiling recovery tower 8 is connected to the primary crude distillation tower 3 and is used to separate the reflux product from the primary crude distillation tower 3. The secondary crude distillation tower 4 is connected to the primary crude distillation tower 3 and is used to separate and purify the bottom product from the primary crude distillation tower 3. After separation and purification in the primary crude distillation tower 3, dichlorosilane and a small amount of trichlorosilane are refluxed from the primary crude distillation tower 3 to the low-boiling recovery tower 8, while a large amount of trichlorosilane is collected from the bottom of the primary crude distillation tower 3 to the secondary crude distillation tower 4. The low-boiling recovery tower 8 separates the trichlorosilane and dichlorosilane collected from the reflux of the primary crude distillation tower 3, and the trichlorosilane is collected from the bottom of the low-boiling recovery tower 8 to the light component removal tower 12. In a preferred embodiment of this invention, a trichlorosilane purification system in the polycrystalline silicon production process further includes: a disproportionation device 9 and a hydrogenation disproportionation fractionation tower 10; the disproportionation device 9 is connected to a low-boiling recovery tower 8; the material inlet of the hydrogenation disproportionation fractionation tower 10 is connected to the disproportionation device 9; the material outlet of the hydrogenation disproportionation fractionation tower 10 is connected to the material inlet of the low-boiling recovery tower 8. The dichlorosilane refluxed from the low-boiling recovery tower 8 is transported to the disproportionation device 9. The packing material of the disproportionation device 9 is a disproportionation resin. Under the catalytic action of the disproportionation resin, dichlorosilane reacts with silicon tetrachloride to produce trichlorosilane, with a single reaction efficiency of over 90%; simultaneously, the disproportionation resin also has the function of adsorbing impurities such as boron. The reacted trichlorosilane, dichlorosilane, and unreacted silicon tetrachloride are collected from the top of the disproportionation unit 9 and fed into the hydrogenation disproportionation fractionation tower 10. The hydrogenation disproportionation fractionation tower 10 separates and purifies the trichlorosilane, dichlorosilane, and silicon tetrachloride input from the disproportionation unit 9. Silicon tetrachloride is collected from the bottom of the hydrogenation disproportionation fractionation tower 10 and fed into the cold hydrogenation system. Trichlorosilane and dichlorosilane are refluxed from the hydrogenation disproportionation fractionation tower 10 and fed into the low-boiling recovery tower 8.

[0056] The primary distillation column 5 is connected to the secondary crude distillation column 4, and is used to remove heavy metals from the reflux product of the secondary crude distillation column 4. The high-boiling recovery column 11 is connected to the primary distillation column 5, and is used to remove heavy metals from the bottom of the primary distillation column 5. The primary distillation column 5 further removes heavy metals from trichlorosilane. A small amount of heavy component impurities and trichlorosilane are collected from the bottom of the primary distillation column 5 and sent to the high-boiling recovery column 11. A large amount of trichlorosilane is refluxed from the primary distillation column 5 and sent to the secondary distillation column 6. A large amount of trichlorosilane is refluxed from the high-boiling recovery column 11 and sent to the light metal removal column 12. A small amount of heavy component impurities, monomethyldichlorosilane, and some trichlorosilane are collected from the bottom of the high-boiling recovery column 11 and sent to the hydrolysis treatment system.

[0057] The secondary distillation column 6 is connected to the primary distillation column 5 and is used to remove light components from the reflux product of the primary distillation column 5. The secondary distillation column 6 is also connected to the primary crude distillation column 3 and is used to reflux a portion of the product to the primary crude distillation column 3 for purification. The secondary distillation column 6 removes light components from trichlorosilane, and a small amount of light component impurities and trichlorosilane are refluxed from the secondary distillation column 6 to the primary crude distillation column 3. A large amount of trichlorosilane is collected from the bottom of the secondary distillation column 6 and sent to the tertiary distillation column 7.

[0058] The third-stage distillation column 7 is connected to the second-stage distillation column 6 and is used to remove heavy components from the bottom of the second-stage distillation column 6. The third-stage distillation column 7 can also reflux trichlorosilane. The refluxed trichlorosilane is transported to a trichlorosilane storage tank for storage or pumped to the reduction process to produce polysilicon. The bottom of the third-stage distillation column 7 is connected to the first-stage distillation column 5, and a portion of the bottom material from the third-stage distillation column 7 is refluxed to the first-stage distillation column 5 for further purification. The crude distillation column further removes heavy components from the trichlorosilane. Heavy impurities and a small amount of trichlorosilane are collected from the bottom of the third-stage distillation column 7 and transported to the first-stage distillation column 5. The large amount of trichlorosilane is refluxed from the crude distillation column to a trichlorosilane storage tank or pumped to the reduction process to produce polysilicon.

[0059] The material inlet of the light component removal tower 12 is connected to the bottom of the low-boiling recovery tower 8, and is used to remove light components from the bottom of the low-boiling recovery tower 8. The material inlet of the light component removal tower 12 is connected to the high-boiling recovery tower 11, and is used to remove light components from the reflux product of the high-boiling recovery tower 11. The reflux product outlet of the light component removal tower 12 is connected to the low-boiling recovery tower 8. The light component removal tower 12 further removes trichlorosilane from the bottom of the low-boiling recovery tower 8 and the reflux product of the high-boiling recovery tower 11. A small amount of light component impurities and trichlorosilane are refluxed from the light component removal tower 12 to the low-boiling recovery tower 8, and a large amount of trichlorosilane is collected from the bottom of the light component removal tower 12 to the heavy component removal tower 13. The material inlet of the heavy component removal tower 13 is connected to the bottom product outlet of the light component removal tower 12.

[0060] The high-boiling-point recovery tower 11 is connected to the bottom of the deweighting tower 13 for deweighting the material collected from the bottom of the deweighting tower 13. Preferably, in this embodiment, a liquid-phase adsorption device 17 is connected between the deweighting tower 13 and the high-boiling-point recovery tower 11 for adsorbing metallic impurities such as boron and phosphorus from trichlorosilane. More preferably, the adsorbent used in the liquid-phase adsorption device 17 is modified activated carbon, adsorption resin, or silica gel. Even more preferably, resin or modified activated carbon is used, and the boron and phosphorus adsorption efficiency can reach over 50%.

[0061] The gas phase outlet of the deweight removal tower 13 is connected to the inlet of the gas phase adsorption device 16. Preferably, in this embodiment, the adsorbent used in the gas phase adsorption device 16 is silica-alumina gel, activated carbon, or molecular sieve. The selection of the adsorbent can be based on a comprehensive consideration of safety, adsorption efficiency, and other factors. The adsorbent used in the gas phase adsorption device 16 differs from that used in the liquid phase adsorption device 17. Due to the different characteristics of the adsorbents, different adsorbents can uniformly adsorb impurities in the material.

[0062] The inlet of the light fractionation tower 14 is connected to the outlet of the gas phase adsorption device 16; the reflux outlet of the light fractionation tower 14 is connected to the light fraction removal tower 12; the heavy fractionation tower 15 is connected to the bottom of the light fractionation tower 14 and is used for the removal of heavy materials from the bottom of the light fractionation tower 14; the heavy fractionation tower 15 can reflux and collect trichlorosilane. The collected trichlorosilane is transported to a trichlorosilane storage tank for storage or pumped to the reduction process to produce polysilicon.

[0063] The deweighting tower 13 further deweights the trichlorosilane. A small amount of heavy component impurities and trichlorosilane are collected from the bottom of the deweighting tower 13 and sent to the liquid phase adsorption unit 17. The liquid phase adsorption unit 17 uses a modified activated carbon fixed bed to adsorb metallic impurities such as boron and phosphorus in the trichlorosilane. After adsorption, the liquid phase trichlorosilane exits from the top of the liquid phase adsorption unit 17 and enters the high-boiling recovery tower 11. A large amount of gaseous trichlorosilane is collected from the top gas phase pipeline of the deweighting tower 13 and sent to the gas phase adsorption unit 16. The gas phase adsorption unit 16 uses a silica-alumina gel adsorbent to adsorb trace amounts of metallic impurities such as boron and phosphorus in the gaseous trichlorosilane. After adsorption, the gaseous trichlorosilane exits from the top of the gas phase adsorption unit 16 and goes to the light fractionation tower 14. Light fractionation tower 14 further removes light components from trichlorosilane. A small amount of light component impurities and trichlorosilane are refluxed from light fractionation tower 14 to light component removal tower 12, while a large amount of trichlorosilane is collected from the bottom of light fractionation tower 14 to heavy fractionation tower 15. Heavy fractionation tower 15 further removes heavy components from trichlorosilane. A small amount of heavy component impurities and trichlorosilane are collected from the bottom of heavy fractionation tower 15 to heavy component removal tower 13, while a large amount of qualified trichlorosilane is refluxed from heavy fractionation tower 15 to a trichlorosilane storage tank or pumped to the reduction process for polysilicon production. Preferably, in the above embodiment, the hydrolysis treatment system is connected to the bottom of high-boiling recovery tower 11 for hydrolysis treatment of the bottom product of high-boiling recovery tower 11.

[0064] One embodiment of the present invention provides a trichlorosilane purification system in the polysilicon production process. This system purifies and separates the materials output from the low-boiling-point recovery tower 8 and the high-boiling-point recovery tower 11, with a relatively small processing capacity. When the system fluctuates, or the impurity content of the cold hydrogenation feed suddenly increases, the residual material discharged from the low-boiling-point recovery tower 8 and the high-boiling-point recovery tower 11 flows to the secondary processing system, which consists of a light-light separation tower 12, a heavy-light separation tower 13, a light separation tower 14, and a heavy separation tower 15. Impurities will preferentially accumulate in the residual material processing system, causing a certain impact on the secondary processing system. This reduces the impact on the main processing system, which consists of a primary distillation tower 3, a secondary distillation tower 4, a primary rectification tower 5, a secondary rectification tower 6, and a tertiary rectification tower 7, ensuring the stability of the trichlorosilane output from the main processing system. Because the secondary processing system has a smaller load, it is more resistant to quality fluctuations and can cope with the impact of general quality fluctuations. This improves the stability and reliability of the rectification system under high load operation, ensuring the stability of the polysilicon product quality.

[0065] An embodiment of the present invention provides a trichlorosilane purification system in the polysilicon production process, which can improve the stability and reliability of the distillation system under high load operation, ensure the quality stability of trichlorosilane, and thus reduce the impact on the quality of polysilicon products.

[0066] As a preferred embodiment of the above, refer to Figure 2 The crude distillation secondary column 4 has a reflux feed inlet, which is connected to the bottom of the crude distillation primary column 3. The input end of the bottom pump 18 is connected to the bottom of the crude distillation secondary column 4, and the output end of the bottom pump 18 is connected to the complexing reflux port of the crude distillation secondary column 4. The complexing reflux port of the crude distillation secondary column 4 is located above the reflux feed inlet. The crude distillation secondary column 4 utilizes siloxane complexation for impurity removal. During operation, a large amount of siloxane is transported through the bottom pump 18 to the top of the reflux feed inlet, where it comes into countercurrent contact with the reflux feed from the crude distillation primary column 3 on the packing. The siloxane complexes boron, phosphorus, and other metallic impurities in the feed. Further preferably, an embodiment of the present invention provides a trichlorosilane purification system in the polycrystalline silicon production process, which further includes a hydrolysis treatment system connected to the output end of the bottom pump 18. Because the complex has a high boiling point, it accumulates and concentrates in the bottom of the crude distillation secondary column 4. Small quantities can be drawn off intermittently or continuously via the bottom pump 18 and sent to the hydrolysis treatment system for hydrolysis. Further preferably, the crude distillation secondary column 4 is equipped with a siloxane replenishment port 4-1, located above the reflux feed inlet, for the input of siloxane. When the crude distillation secondary column 4 lacks siloxane, it can be replenished from the feed line from the tank area through the siloxane replenishment port 4-1. The complexed trichlorosilane is drawn off from the outlet of the reflux pump and sent to the rectification primary column 5.

[0067] As a preferred embodiment of the above, the crude distillation secondary column 4 uses siloxane complexation to remove metallic impurities such as boron and phosphorus from trichlorosilane. This can complex impurities with boiling points close to those of trichlorosilane, and better ensure the quality of the distillation liquid product, trichlorosilane.

[0068] As a preferred embodiment of the above embodiments, one embodiment of the present invention provides a trichlorosilane purification system in the polycrystalline silicon production process, which further includes: a cold hydrogenation system; the cold hydrogenation system is connected to the bottom of the cold hydrogenation primary separation tower 2; the cold hydrogenation system is connected to the bottom of the hydrogenation disproportionation fractionation tower 10, for cold hydrogenation treatment of the bottom product of the hydrogenation disproportionation fractionation tower 10.

[0069] An embodiment of the present invention provides a trichlorosilane purification system in the polycrystalline silicon production process. During operation, the secondary processing system has a small load and good parameter controllability. At the same time, a gas phase adsorption device 16 and a liquid phase adsorption device 17 are added to enhance the impurity removal capability. When the quality fluctuates, the quality fluctuation can be easily controlled by increasing the reflux ratio, increasing the residual discharge, and short-term material sealing, so as to minimize the loss.

[0070] Taking a distillation system with an annual production capacity of 50,000 tons of polysilicon as an example, after the implementation of this invention, the main processing system accounts for approximately 70% to 90% of the total load, and the secondary processing system accounts for approximately 10% to 30% of the total load. When the system fluctuates or the impurity content increases, it will affect at most 10% to 30% of the total load, while the remaining 70% to 90% will maintain stable quality.

[0071] To further clarify, while the terms "first," "second," etc., may be used herein to describe various elements, these terms should not limit the elements. These terms are used only to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element; these terms are used only to distinguish one element from another. This does not depart from the scope of the exemplary embodiments. Similarly, "element one," "element two," and so on do not represent the order of elements; these terms are used only to distinguish one element from another. As used herein, the term "and / or" includes any and all combinations of one or more associated listed items.

[0072] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0073] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A trichlorosilane purification system in the polycrystalline silicon production process, characterized in that, Includes: cold hydrogenation primary separation column, crude distillation primary column, low-boiling recovery column, crude distillation secondary column, rectification primary column, high-boiling recovery column, rectification secondary column, rectification tertiary column, light component removal column, heavy component removal column, light component separation column, and heavy component separation column; The cold hydrogenation primary separation tower is used to separate and purify the synthesized materials; The crude distillation primary column is connected to the cold hydrogenation initial separation column; The low-boiling recovery tower is connected to the primary crude distillation tower and is used to separate the reflux product from the primary crude distillation tower. The secondary crude distillation column is connected to the primary crude distillation column and is used to separate and purify the bottom product of the primary crude distillation column. The primary distillation column is connected to the secondary crude distillation column and is used to deweight the reflux product from the secondary crude distillation column. The high-boiling recovery tower is connected to the first-stage distillation tower and is used to degravate the material collected from the bottom of the first-stage distillation tower. The secondary distillation column is connected to the primary distillation column and is used to remove light substances from the reflux product of the primary distillation column. The secondary distillation column is connected to the primary crude distillation column, and is used to reflux a portion of the material to the primary crude distillation column for purification. The third-stage distillation column is connected to the second-stage distillation column and is used to remove weight from the bottom of the second-stage distillation column; the third-stage distillation column can reflux and collect trichlorosilane. The reboiler of the three-stage distillation column is connected to the first-stage distillation column, so that part of the material from the reboiler of the three-stage distillation column can be refluxed to the first-stage distillation column for further purification. The material inlet of the light-light removal tower is connected to the bottom of the low-boiling recovery tower, and is used to remove light-light materials from the bottom of the low-boiling recovery tower. The material inlet of the light-light removal tower is connected to the high-boiling-point recovery tower and is used to remove light-light materials from the reflux of the high-boiling-point recovery tower. The reflux outlet of the light-light-removal tower is connected to the low-boiling-point recovery tower; The material inlet of the heavy removal tower is connected to the bottom outlet of the light removal tower; The high-boiling-point recovery tower is connected to the bottom of the deweighting tower and is used to deweight the material collected from the bottom of the deweighting tower. The gas phase outlet of the deweight removal tower is connected to the inlet of the gas phase adsorption device; The inlet of the light separation tower is connected to the outlet of the gas phase adsorption device; the reflux outlet of the light separation tower is connected to the light removal tower. The heavy separation tower is connected to the bottom of the light separation tower and is used for deweighting the material collected from the bottom of the light separation tower; the heavy separation tower can reflux and collect trichlorosilane.

2. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 1, characterized in that, Also includes: Disproportionation unit and hydrogenation disproportionation fractionation tower; The anti-disproportionation device is connected to the low-boiling recovery tower; The material inlet of the hydrogenation disproportionation fractionation tower is connected to the disproportionation device; The material outlet of the hydrogenation disproportionation fractionation tower is connected to the material inlet of the low-boiling recovery tower.

3. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 1, characterized in that, The crude distillation secondary column has a reflux feed inlet, which is connected to the bottom of the crude distillation primary column; The input end of the reboiler pump is connected to the reboiler of the crude distillation secondary column; The output end of the bottom pump is connected to the complexation reflux port of the crude distillation secondary column; The complexation reflux port of the crude distillation secondary column is located above the reflux feed outlet.

4. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 3, characterized in that, Also includes: Hydrolysis treatment system; The hydrolysis treatment system is connected to the output end of the bottom pump of the tower.

5. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 4, characterized in that, The crude distillation secondary column is equipped with a siloxane replenishment port, which is located above the reflux outfeed inlet and is used for the input of siloxane.

6. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 5, characterized in that, The hydrolysis treatment system is connected to the bottom of the high-boiling recovery tower.

7. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 2, characterized in that, Also includes: Cold hydrogenation system; The cold hydrogenation system is connected to the bottom of the cold hydrogenation primary separation tower; The cold hydrogenation system is connected to the bottom of the hydrogenation disproportionation fractionation tower.

8. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 1, characterized in that, A liquid phase adsorption device is connected between the deweight removal tower and the high-boiling recovery tower.

9. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 8, characterized in that, The liquid phase adsorption device uses modified activated carbon, adsorption resin, or silica gel as the adsorbent. The adsorbent used in the gas phase adsorption device is silica-alumina gel, activated carbon, or molecular sieve. The adsorbent used in the gas phase adsorption device is different from the adsorbent used in the liquid phase adsorption device.

10. The trichlorosilane purification system in the polycrystalline silicon production process according to claim 1, characterized in that, The crude distillation secondary column uses siloxane for complexation and impurity removal.

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