Trichlorosilane purification system in polycrystalline silicon production process

Abstract

The utility model relates to the technical field of polycrystalline silicon production equipment, in particular to a trichlorosilane purification system in a polycrystalline silicon production process, which is characterized in that a coarse distillation primary tower is communicated with a cold hydrogenation primary separation tower; the low-boiling-point recovery tower is communicated with the primary crude distillation tower; the crude distillation secondary tower is communicated with the crude distillation primary tower; the rectification primary tower is communicated with the crude distillation secondary tower; the high-boiling recovery tower is communicated with the rectification primary tower; the rectifying secondary tower is communicated with the rectifying primary tower; the rectification secondary tower is communicated with the crude distillation primary tower; the third-stage rectification tower is communicated with the second-stage rectification tower; a tower kettle of the third-stage rectification tower is communicated with the first-stage rectification tower; the light component removal tower is communicated with the low-boiling-point recovery tower and the high-boiling-point recovery tower; the heavy component removal tower is communicated with the light component removal tower; the high-boiling recovery tower is communicated with the tower kettle of the de-heavy tower; a gas phase outlet of the heavy component removal tower is sequentially connected with a gas phase adsorption device and a light component tower; a reflux inlet of the light component tower is communicated with the light component removal tower; and the heavy separation tower is communicated with the light separation tower. According to the utility model, the stability and reliability of large-load operation of the rectification system can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon production equipment, in particular to a trichlorosilane purification system in the polysilicon production process. Background Art

[0002] In the process of producing polysilicon by the modified Siemens method, the mixture of dichlorosilane, trichlorosilane and silicon tetrachloride synthesized in the cold hydrogenation process needs to be sent to the distillation system for distillation. The distillation system purifies trichlorosilane through multi-stage distillation to achieve a qualified product with extremely high purity, and then it is sent to the reduction furnace for the production of polysilicon. In recent years, in order to reduce investment and operating costs, improve economies of scale, further save energy consumption and improve economic benefits, the production capacity of polysilicon production equipment has been gradually expanded, and the scale of the distillation system has also become larger and larger. However, the expansion of the scale of the distillation system will affect the refinement of the distillation tower parameter control and the stability of the distillation tower operation; especially when the distillation system is running at high load, the refinement of the distillation tower parameter control will be relatively worse, and the stability of the operation will also be worse; when the system fluctuates or the impurity content of the cold hydrogenation feed suddenly increases, the impurities will be enriched in the distillation system, causing an impact on the distillation system. Since the existing distillation system is a single-line distillation, impurities enriched in the distillation system will directly affect the quality stability of the output liquid trichlorosilane, further resulting in poor quality controllability and frequent quality fluctuations in the later production of polysilicon, which greatly affects the economic benefits. Utility Model Content

[0003] In view of this, the utility model 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 thereby reduce the impact on the quality of polysilicon products.

[0004] In order to achieve the above purpose, the utility model mainly provides the following technical solutions:

[0005] The embodiment of the utility model provides a trichlorosilane purification system in a polysilicon production process, comprising: a cold hydrogenation primary separation tower, a crude distillation primary tower, a low boiling recovery tower, a crude distillation secondary tower, a rectification primary tower, a high boiling recovery tower, a rectification secondary tower, a rectification tertiary tower, a light removal tower, a heavy removal tower, a light separation tower and a heavy separation tower;

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

[0007] The crude distillation primary tower is connected to the cold hydrogenation primary fractionation tower;

[0008] The low boiling recovery tower is connected to the primary crude distillation tower and is used to separate the reflux produced materials of the primary crude distillation tower;

[0009] The secondary crude distillation tower is connected to the primary crude distillation tower and is used to separate and purify the materials produced from the bottom of the primary crude distillation tower;

[0010] The primary rectification tower is connected to the secondary crude distillation tower, and is used to perform a weight removal treatment on the reflux produced material of the secondary crude distillation tower;

[0011] The high boiling recovery tower is connected to the primary distillation tower and is used to remove the weight of the material produced from the bottom of the primary distillation tower;

[0012] The secondary distillation tower is connected to the primary distillation tower and is used to remove light materials from the reflux produced materials of the primary distillation tower;

[0013] The secondary rectification tower is connected to the primary crude distillation tower, and is used to reflux part of the materials to the primary crude distillation tower for purification;

[0014] The three-stage distillation tower is connected to the two-stage distillation tower, and is used to remove the weight of the material produced from the bottom of the two-stage distillation tower; the three-stage distillation tower can reflux and produce trichlorosilane;

[0015] The bottom of the three-stage distillation tower is connected to the first-stage distillation tower, so that part of the materials in the bottom of the three-stage distillation tower are refluxed to the first-stage distillation tower for further purification;

[0016] The material inlet of the light removal tower is connected to the bottom of the low-boiling recovery tower, so as to remove light from the material produced from the bottom of the low-boiling recovery tower;

[0017] The material inlet of the light removal tower is connected to the high boiling point recovery tower, and is used for performing light removal treatment on the reflux produced material of the high boiling point recovery tower;

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

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

[0020] The high boiling recovery tower is connected to the bottom of the de-weighting tower, and is used to perform de-weighting treatment on the material produced from the bottom of the de-weighting tower;

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

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

[0023] The heavy fraction tower is connected to the bottom of the light fraction tower, and is used for removing the heavy materials from the bottom of the light fraction tower; the heavy fraction tower can reflux and produce trichlorosilane.

[0024] Furthermore, it also includes: an anti-disproportionation device and a hydrogenation anti-disproportionation fractionation tower;

[0025] The anti-disproportionation device is in communication with the low-boiling recovery tower;

[0026] The material inlet of the hydrogenation anti-disproportionation fractionation tower is in communication with the anti-disproportionation device;

[0027] The material outlet of the hydrogenation and deproportionation fractionation tower is communicated with the material inlet of the low-boiling recovery tower.

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

[0029] The input end of the tower bottom pump is communicated with the tower bottom of the crude distillation secondary tower;

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

[0031] The complex reflux port of the crude distillation secondary tower is located above the reflux extraction feed port.

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

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

[0034] Furthermore, the crude distillation secondary tower siloxane is provided with a siloxane replenishing port, and the siloxane replenishing port is located above the reflux withdrawal feed port 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] Further, it also includes: a cold hydrogenation system;

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

[0038] The cold hydrogenation system is communicated with the bottom of the hydrogenation anti-disproportionation fractionation tower.

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

[0040] Furthermore, the adsorbent used in the liquid phase adsorption device is modified activated carbon or 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 tower uses siloxane for complexation and impurity removal.

[0044] By means of the above technical solution, the trichlorosilane purification system in the polysilicon production process of the utility model has at least the following advantages:

[0045] It 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.

[0046] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the utility model in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of a trichlorosilane purification system in a polysilicon production process provided by an embodiment of the utility model;

[0048] Figure 2 A system schematic diagram of a crude distillation secondary tower in a trichlorosilane purification system in a polysilicon production process provided by an embodiment of the utility model.

[0049] As shown in the figure:

[0050] 1 is a synthetic material storage tank, 2 is a cold hydrogenation primary fractionation tower, 3 is a crude distillation primary tower, 4 is a crude distillation secondary tower, 4-1 is a siloxane supply port, 5 is a rectification primary tower, 6 is a rectification secondary tower, 7 is a rectification tertiary tower, 8 is a low-boiling recovery tower, 9 is an anti-disproportionation device, 10 is a hydrogenation anti-disproportionation fractionation tower, 11 is a high-boiling recovery tower, 12 is a light removal tower, 13 is a heavy removal tower, 14 is a light fractionation tower, 15 is a heavy fractionation tower, 16 is a gas phase adsorption device, 17 is a liquid phase adsorption device, and 18 is a tower bottom pump. DETAILED DESCRIPTION

[0051] In order to further explain the technical means and effects adopted by the utility model to achieve the predetermined utility model purpose, the specific implementation methods, structures, features and effects of the utility model application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0052] like Figure 1As shown, a trichlorosilane purification system in a polysilicon production process proposed by an embodiment of the utility model comprises: a cold hydrogenation primary fractionation tower 2, a crude distillation primary tower 3, a low boiling recovery tower 8, a crude distillation secondary tower 4, a rectification primary tower 5, a high boiling recovery tower 11, a rectification secondary tower 6, a rectification tertiary tower 7, a light removal tower 12, a heavy removal tower 13, a light fractionation tower 14, and a heavy fractionation tower 15. The cold hydrogenation primary fractionation tower 2, the crude distillation primary tower 3, the low boiling recovery tower 8, the crude distillation secondary tower 4, the rectification primary tower 5, the high boiling recovery tower 11, the rectification secondary tower 6, and the rectification tertiary tower 7 constitute the main processing system for purifying trichlorosilane. The light removal tower 12, the heavy removal tower 13, the light fractionation tower 14, and the heavy fractionation tower 15 constitute the secondary processing system for purifying trichlorosilane, which mainly processes the discharge residues of the low boiling recovery tower 8 and the high boiling 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 feed port 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 crude distillation primary tower 3 is connected to the cold hydrogenation primary fractionation tower 2; after separation and purification in the cold hydrogenation primary fractionation tower 2, 99.5% of the silicon tetrachloride is returned from the bottom of the cold hydrogenation primary fractionation tower 2 to the cold hydrogenation system; trichlorosilane and dichlorodihydrosilane are refluxed from the cold hydrogenation primary fractionation tower 2 and extracted to the crude distillation primary tower 3.

[0055] The low-boiling recovery tower 8 is connected to the crude distillation primary tower 3, and is used to separate the refluxed material of the crude distillation primary tower 3; the crude distillation secondary tower 4 is connected to the crude distillation primary tower 3, and is used to separate and purify the material produced from the bottom of the crude distillation primary tower 3; after separation and purification in the crude distillation primary tower 3, dichlorosilane and a small amount of trichlorosilane are refluxed from the crude distillation primary tower 3 to the low-boiling recovery tower 8, and a large amount of trichlorosilane is produced from the bottom of the crude distillation primary tower 3 to the crude distillation secondary tower 4. The low-boiling recovery tower 8 separates trichlorosilane and dichlorosilane refluxed from the crude distillation primary tower 3, and trichlorosilane is produced from the bottom of the low-boiling recovery tower 8 to the lightness removal tower 12. This embodiment is preferred. A trichlorosilane purification system in a polysilicon production process proposed in an embodiment of the utility model also includes: a deproportionation device 9 and a hydrogenation deproportionation fractionation tower 10; the deproportionation device 9 is connected to a low-boiling recovery tower 8; the material inlet of the hydrogenation deproportionation fractionation tower 10 is connected to the deproportionation device 9; the material outlet of the hydrogenation deproportionation fractionation tower 10 is connected to the material inlet of the low-boiling recovery tower 8. The dichlorodihydrosilane refluxed from the low-boiling recovery tower 8 is transported to the deproportionation device 9. The filler of the deproportionation device 9 is deproportionation resin. Under the catalytic action of the deproportionation resin, dichlorodihydrosilane reacts with silicon tetrachloride to generate trichlorosilane, and the primary reaction efficiency can reach more than 90%; at the same time, the deproportionation resin also has the function of adsorbing impurities such as boron. The trichlorosilane, dichlorosilane and silicon tetrachloride that have not participated in the reaction are extracted from the top of the deproportionation device 9 to the hydrogenation deproportionation fractionation tower 10; the hydrogenation deproportionation fractionation tower 10 separates and purifies the trichlorosilane, dichlorosilane and silicon tetrachloride input from the deproportionation device 9, silicon tetrachloride is extracted from the bottom of the hydrogenation deproportionation fractionation tower 10 to the cold hydrogenation system, and trichlorosilane and dichlorosilane are refluxed from the hydrogenation deproportionation fractionation tower 10 to the low-boiling recovery tower 8.

[0056] The primary distillation tower 5 is connected to the secondary crude distillation tower 4, and is used to remove the weight of the refluxed material of the secondary crude distillation tower 4; the high boiling recovery tower 11 is connected to the primary distillation tower 5, and is used to remove the weight of the material extracted from the bottom of the primary distillation tower 5; the primary distillation tower 5 removes the weight of trichlorosilane again, and a small amount of heavy component impurities and trichlorosilane are extracted from the bottom of the primary distillation tower 5 to the high boiling recovery tower 11; a large amount of trichlorosilane is refluxed from the primary distillation tower 5 to the secondary distillation tower 6. A large amount of trichlorosilane is refluxed from the high boiling recovery tower 11 to the light removal tower 12, and a small amount of heavy component impurities, monomethyldichlorosilane and part of trichlorosilane are extracted from the bottom of the high boiling recovery tower 11 to the hydrolysis treatment system.

[0057] The secondary distillation tower 6 is connected to the primary distillation tower 5, and is used for removing light impurities from the refluxed material of the primary distillation tower 5; the secondary distillation tower 6 is connected to the primary crude distillation tower 3, and is used for refluxing part of the material to the primary crude distillation tower 3 for purification; the secondary distillation tower 6 removes light impurities from trichlorosilane, and a small amount of light component impurities and trichlorosilane are refluxed from the secondary distillation tower 6 and extracted to the primary crude distillation tower 3; a large amount of trichlorosilane is extracted from the bottom of the secondary distillation tower 6 to the tertiary distillation tower 7.

[0058] The three-stage rectifying tower 7 is connected to the two-stage rectifying tower 6, and is used to remove the weight of the material extracted from the bottom of the two-stage rectifying tower 6; the three-stage rectifying tower 7 can reflux and extract trichlorosilane; the extracted trichlorosilane is transported to the trichlorosilane storage tank for storage or pumped to the reduction process to produce polysilicon. The bottom of the three-stage rectifying tower 7 is connected to the first-stage rectifying tower 5, and part of the materials in the bottom of the three-stage rectifying tower 7 are refluxed to the first-stage rectifying tower 5 for further purification; the three-stage crude distillation tower removes the weight of trichlorosilane again, and the heavy component impurities and a small amount of trichlorosilane are extracted from the bottom of the three-stage rectifying tower 7 to the first-stage rectifying tower 5, and a large amount of trichlorosilane is refluxed from the three-stage crude distillation tower to the trichlorosilane storage tank or pumped to the reduction process to produce polysilicon.

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

[0060] The high boiling recovery tower 11 is connected to the bottom of the deweighting tower 13, and is used to deweight the materials extracted from the bottom of the deweighting tower 13; in this embodiment, preferably, a liquid phase adsorption device 17 is connected between the deweighting tower 13 and the high boiling recovery tower 11, and is used to adsorb metal impurities such as boron and phosphorus in trichlorosilane. It is further preferred that the adsorbent used in the liquid phase adsorption device 17 is modified activated carbon or adsorption resin or silica gel. It is further preferred that the resin or modified activated carbon, and the boron and phosphorus adsorption efficiency can reach more than 50%.

[0061] The gas phase outlet of the deweighting tower 13 is connected to the inlet of the gas phase adsorption device 16; in this embodiment, the adsorbent used by the gas phase adsorption device 16 is preferably silica-alumina gel or activated carbon or molecular sieve, and the selection of the adsorbent can be comprehensively considered from the perspectives of safety, adsorption efficiency, etc. The adsorbent used by the gas phase adsorption device 16 is different from the adsorbent used by the liquid phase adsorption device 17. Due to the different characteristics of the adsorbents, different adsorbents can adsorb impurities in the material in a balanced manner.

[0062] The inlet of the light fraction tower 14 is connected to the outlet of the gas phase adsorption device 16; the reflux outlet of the light fraction tower 14 is connected to the light removal tower 12; the heavy fraction tower 15 is connected to the bottom of the light fraction tower 14, and is used for the material produced from the bottom of the light fraction tower 14 to remove the heavy weight; the heavy fraction tower 15 can reflux and produce trichlorosilane. The produced trichlorosilane is transported to the trichlorosilane storage tank for storage or transported to the reduction process by a pump to produce polysilicon.

[0063] The de-weighting tower 13 de-weights the trichlorosilane again, and a small amount of heavy component impurities and trichlorosilane are extracted from the bottom of the de-weighting tower 13 to the liquid phase adsorption device 17. The liquid phase adsorption device 17 uses a modified activated carbon fixed bed to adsorb metal impurities such as boron and phosphorus in the trichlorosilane. The liquid phase trichlorosilane after adsorption is discharged from the top of the liquid phase adsorption device 17 and enters the high-boiling recovery tower 11. A large amount of gas phase trichlorosilane is extracted from the gas phase pipeline at the top of the de-weighting tower 13 to the gas phase adsorption device 16. The gas phase adsorption device 16 uses a silica-alumina gel adsorbent to adsorb trace metal impurities such as boron and phosphorus in the gas phase trichlorosilane. The gas phase of the trichlorosilane after adsorption is discharged from the top of the gas phase adsorption device 16 to the light fraction tower 14. The light fraction tower 14 further removes light components from the trichlorosilane, and a small amount of light component impurities and trichlorosilane are refluxed from the light fraction tower 14 to the light removal tower 12, and a large amount of trichlorosilane is extracted from the bottom of the light fraction tower 14 to the heavy fraction tower 15. The heavy fraction tower 15 removes heavy components from the trichlorosilane again, and a small amount of heavy component impurities and trichlorosilane are extracted from the bottom of the heavy fraction tower 15 to the heavy removal tower 13, and a large amount of qualified trichlorosilane is refluxed from the heavy fraction tower 15 to the trichlorosilane storage tank or pumped to the reduction process to produce polysilicon. As a preferred embodiment of the above, the hydrolysis treatment system is connected to the bottom of the high boiling recovery tower 11, and is used to hydrolyze the material extracted from the bottom of the high boiling recovery tower 11.

[0064] An embodiment of the utility model proposes a trichlorosilane purification system in a polysilicon production process, which purifies and separates the materials output by the low-boiling recovery tower 8 and the high-boiling recovery tower 11, and the processing capacity is relatively small; when the system fluctuates, or the impurity content of the cold hydrogenation incoming material suddenly rises, the waste material produced by the low-boiling recovery tower 8 and the high-boiling recovery tower 11 will flow to the secondary processing system composed of the light removal tower 12, the heavy removal tower 13, the light fraction tower 14 and the heavy fraction tower 15, and the impurities will be preferentially enriched in the waste material processing system, which will cause a certain impact on the secondary processing system, thereby reducing the impact on the main processing system composed of the crude distillation first-stage tower 3, the crude distillation second-stage tower 4, the rectification first-stage tower 5, the rectification second-stage tower 6 and the rectification third-stage tower 7, and ensuring the stability of the trichlorosilane output by the main processing system. Because the load of the secondary processing system is small, the risk of resisting quality fluctuations is relatively large, and it can cope with the impact of general quality fluctuations, thus improving the stability and reliability of the distillation system under high load operation, and ensuring the stability of the quality of polysilicon products.

[0065] An embodiment of the utility model provides a trichlorosilane purification system in a 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 tower 4 is provided with a reflux extraction feed port, which is connected to the bottom of the crude distillation primary tower 3; the input end of the bottom pump 18 is connected to the bottom of the crude distillation secondary tower 4; the output end of the bottom pump 18 is connected to the complexation reflux port of the crude distillation secondary tower 4; the complexation reflux port of the crude distillation secondary tower 4 is located above the reflux extraction feed port. The crude distillation secondary tower 4 uses siloxane complexation to remove impurities. During operation, a large amount of siloxane is transported to the top of the reflux extraction feed port through the bottom pump 18, and countercurrently contacts with the reflux extraction material of the crude distillation primary tower 3 on the filler, and siloxane will complex metal impurities such as boron and phosphorus in the feed. Further preferably, a trichlorosilane purification system in a polysilicon production process proposed in an embodiment of the utility model also includes: a hydrolysis treatment system; the hydrolysis treatment system is connected to the output end of the bottom pump 18. Since the complex has a high boiling point, it is concentrated in the bottom of the crude distillation secondary tower 4 and can be intermittently or continuously extracted in small quantities to the hydrolysis treatment system through the bottom pump 18 for hydrolysis treatment. Further preferably, a siloxane replenishment port 4-1 is provided on the crude distillation secondary tower 4, and the siloxane replenishment port 4-1 is located above the reflux extraction feed port for the input of siloxane. When the crude distillation secondary tower 4 lacks siloxane, it can be replenished from the feed pipeline from the tank area through the siloxane replenishment port 4-1. The trichlorosilane after complexation treatment is extracted from the outlet of the reflux pump to the distillation primary tower 5.

[0067] As a preferred embodiment of the above, the crude distillation secondary tower 4 uses siloxane complexation to remove metal impurities such as boron and phosphorus in trichlorosilane, which can complex impurities with a boiling point close to that of trichlorosilane and better ensure the quality of the distillation liquid product trichlorosilane.

[0068] As a preference for the above embodiments, an embodiment of the utility model proposes a trichlorosilane purification system for a polysilicon production process, which also 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 anti-disproportionation fractionation tower 10, and is used to perform cold hydrogenation treatment on the material extracted from the bottom of the hydrogenation anti-disproportionation fractionation tower 10.

[0069] In the operation of a trichlorosilane purification system in a polysilicon production process proposed by an embodiment of the utility model, since the load of the secondary treatment system is small and the parameter controllability is good, a gas phase adsorption device 16 and a liquid phase adsorption device 17 are added at the same time 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 volume, and sealing the materials for a short time, thereby minimizing the loss.

[0070] Taking the distillation system of 50,000 tons of polysilicon per year as an example, after the implementation of the utility model, the main processing system accounts for about 70% to 90% of the total load, and the secondary processing system accounts for about 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, and the remaining 70% to 90% will still maintain stable quality.

[0071] Further explanation, although the terms first, second, etc. can be used to describe various elements in this article, these terms should not limit these elements. These terms are only used to distinguish one element from another element. For example, the first element can be called the second element, and, similarly, the second element can be called the first element, and these terms are only used to distinguish one element from another element. This does not depart from the scope of exemplary embodiments. Similarly, element one and element two do not represent the order of elements, and these terms are only used to distinguish one element from another element. As used herein, the term "and / or" includes any combination and all combinations of one or more associated listed items.

[0072] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] The standard parts used in the utility model can all be purchased from the market, and special-shaped parts can be customized according to the instructions and the drawings. The specific connection methods of each part adopt the conventional means such as mature bolts, rivets, welding, etc. in the existing technology. The machinery, parts and equipment all adopt the conventional models in the existing technology, and the circuit connection adopts the conventional connection method in the existing technology, which will not be described in detail here.

[0074] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A trichlorosilane purification system in a polysilicon production process, characterized in that: Including: cold hydrogenation primary separation tower, crude distillation first tower, low boiling recovery tower, crude distillation second tower, rectification first tower, high boiling recovery tower, rectification second tower, rectification tertiary tower, light removal tower, heavy removal tower, light separation tower and heavy separation tower; The cold hydrogenation primary separation tower is used to separate and purify the synthetic materials; The crude distillation primary tower is connected to the cold hydrogenation primary fractionation tower; The low boiling recovery tower is connected to the primary crude distillation tower and is used to separate the reflux produced materials of the primary crude distillation tower; The secondary crude distillation tower is connected to the primary crude distillation tower and is used to separate and purify the materials produced from the bottom of the primary crude distillation tower; The primary rectification tower is connected to the secondary crude distillation tower, and is used to perform a weight removal treatment on the reflux produced material of the secondary crude distillation tower; The high boiling recovery tower is connected to the primary distillation tower and is used to remove the weight of the material produced from the bottom of the primary distillation tower; The secondary distillation tower is connected to the primary distillation tower and is used to remove light materials from the reflux produced materials of the primary distillation tower; The secondary rectification tower is connected to the primary crude distillation tower, and is used to reflux part of the materials to the primary crude distillation tower for purification; The three-stage distillation tower is connected to the two-stage distillation tower, and is used to remove the weight of the material produced from the bottom of the two-stage distillation tower; the three-stage distillation tower can reflux and produce trichlorosilane; The bottom of the three-stage distillation tower is connected to the first-stage distillation tower, so that part of the materials in the bottom of the three-stage distillation tower are refluxed to the first-stage distillation tower for further purification; The material inlet of the light removal tower is connected to the bottom of the low-boiling recovery tower, so as to remove light from the material produced from the bottom of the low-boiling recovery tower; The material inlet of the light removal tower is connected to the high boiling point recovery tower, and is used for performing light removal treatment on the reflux produced material of the high boiling point recovery tower; The reflux outlet of the light removal tower is connected to the low boiling recovery tower; The material inlet of the de-heavy tower is connected to the bottom outlet of the light-removal tower; The high boiling recovery tower is connected to the bottom of the de-weighting tower, and is used to perform de-weighting treatment on the material produced from the bottom of the de-weighting tower; The gas phase outlet of the deweighting tower is connected to the inlet of the gas phase adsorption device; The inlet of the light fraction tower is connected to the outlet of the gas phase adsorption device; the reflux outlet of the light fraction tower is connected to the light removal tower; The heavy fraction tower is connected to the bottom of the light fraction tower, and is used for removing the heavy materials from the bottom of the light fraction tower; the heavy fraction tower can reflux and produce trichlorosilane.

2. The trichlorosilane purification system in the polysilicon production process according to claim 1, characterized in that: Also includes: Deproportionation unit and hydrogenation deproportionation fractionation tower; The anti-disproportionation device is in communication with the low-boiling recovery tower; The material inlet of the hydrogenation anti-disproportionation fractionation tower is in communication with the anti-disproportionation device; The material outlet of the hydrogenation and deproportionation fractionation tower is communicated with the material inlet of the low-boiling recovery tower.

3. The trichlorosilane purification system in the polysilicon production process according to claim 1, characterized in that: The secondary crude distillation tower is provided with a reflux feed inlet, and the reflux feed inlet is connected to the bottom of the primary crude distillation tower; The input end of the tower bottom pump is connected to the tower bottom of the crude distillation secondary tower; The output end of the tower bottom pump is connected to the complex reflux port of the crude distillation secondary tower; The complex reflux port of the crude distillation secondary tower is located above the reflux extraction feed port.

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

5. The trichlorosilane purification system in the polysilicon production process according to claim 4, characterized in that: The crude distillation secondary tower siloxane is provided with a siloxane replenishing port, and the siloxane replenishing port is located above the reflux withdrawal feed port and is used for inputting siloxane.

6. The trichlorosilane purification system in the polysilicon production process according to claim 5, characterized in that: The hydrolysis treatment system is communicated with the bottom of the high boiling point recovery tower.

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

8. The trichlorosilane purification system in the polysilicon production process according to claim 1, characterized in that: A liquid phase adsorption device is connected between the deweighting tower and the high boiling point recovery tower.

9. The trichlorosilane purification system in the polysilicon production process according to claim 8, characterized in that: The adsorbent used in the liquid phase adsorption device is modified activated carbon or adsorption resin or silica gel; 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 polysilicon production process according to claim 1, characterized in that: The crude distillation secondary tower uses siloxane for complexation and impurity removal.

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