Rectification system for reducing recycled materials
By designing a distillation system for reducing and recovered materials in the polycrystalline silicon production process, using the anti-disturbance reactor and the silicon tetrachloride purification tower to separate and process the two strands of materials in the exhaust gas recovery section, the increased operation and equipment cost problems in the prior art are solved. , achieving more cost-effective polysilicon production.
Patent Information
- Application Number
- CN202420347121.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-26
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2034-02-26
AI Technical Summary
In the existing polysilicon production process, the separation and purification process of exhaust gas recovery materials has two reduction recovery materials with different temperatures and different dichlorodihydrogen silicon content and are mixed and separated again, which increases the operating cost and equipment cost.
A distillation system for reducing and recovered materials was designed, including a reductive recycling material storage tank, an anti-dispersion reactor and a silicon tetrachloride purification tower. The low-temperature material and silicon tetrachloride material are mixed to form trichlorohydrogen Silicon and output it to the reduction recovery distillation tower, concentrate silicon tetrachloride to the silicon tetrachloride purification tower, dichlorodihydrogen silicon and trichlorosilica enter trichlorosilica storage tank through the top-up pipeline, reducing the The concentration of chlorodihydrogen silicon reduces the separation step.
By separately processing the two strands of materials generated in the exhaust gas recovery section, the operating costs and equipment costs are reduced, a distillation tower is reduced, and the economy and efficiency of the polysilicon production process are optimized.
Smart Images
Figure CN222131012U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of polysilicon production, in particular to a distillation system for reducing and recovering materials. Background Art
[0002] The modified Siemens process is the main production process of polysilicon. The process mainly includes four core sections: cold hydrogenation, distillation, reduction, and tail gas recovery. The cold hydrogenation section converts industrial silicon powder into a chlorosilane mixture (mainly dichlorosilane, trichlorosilane, and silicon tetrachloride, accompanied by other metal and non-metal chloride impurities), the distillation section purifies and separates the chlorosilane mixture into high-purity trichlorosilane, and the reduction section uses the high-purity trichlorosilane obtained in the distillation section to undergo a vapor phase chemical deposition reaction (CVD) in a bell reactor (reduction furnace) to produce polysilicon rods. The tail gas recovery section condenses and cools the high-purity trichlorosilane, hydrogen, and reaction by-products dichlorosilane and silicon tetrachloride that have not participated in the reaction in the bell reactor for recovery. The recovered chlorosilane mixture is sent to the distillation section for further separation and purification to obtain high-purity trichlorosilane, and then enters the reduction section again to produce polysilicon.
[0003] In the prior art, the process flow of separation and purification of reduced recycled materials is as follows:
[0004] like Figure 1 As shown, the tail gas recovery section uses production equipment to condense and cool the chlorosilane vapor mixture sent from the reduction section. In the above condensation and cooling process, due to the extremely strong volatility of chlorosilane and the low freezing point of dichlorosilane, conventional refrigerants can condense most of trichlorosilane and silicon tetrachloride, and only a small part of dichlorosilane is condensed into a liquid phase. Therefore, after the chlorosilane mixture is condensed once, a lower temperature refrigerant is used for deep cooling to condense the uncondensed chlorosilane vapor mixture with dichlorosilane as the main component into a liquid phase. Therefore, after a series of condensation treatments, the chlorosilane vapor mixture is finally condensed into two liquid phase materials, one is a high-temperature material (a chlorosilane mixture with a low dichlorosilane content), and the other is a low-temperature material (a chlorosilane mixture with a high dichlorosilane content). The two materials are mixed and transported to the reduction recovery material storage tank TK01.
[0005] A shielded pump is used to transport the reduction recovery material from the reduction recovery material storage tank TK01 to the reduction recovery primary tower T01 in the distillation section. The kettle-collected material (silicon tetrachloride) of the reduction recovery primary tower T01 goes to the silicon tetrachloride purification tower T03, and the top-collected material (a mixture of trichlorosilane and dichlorosilane) goes to the reduction recovery secondary tower T02.
[0006] The top-collected material (with the content of dichlorosilane component being above 90%) from the secondary reduction recovery tower T02 is divided into two streams, one to the anti-disproportionation reactor R01, and the other to the high-purity trichlorosilane storage tank for proportioning. The side-collected material (high-purity trichlorosilane) is sent to the high-purity trichlorosilane storage tank, and the kettle-collected material is returned to the primary reduction recovery tower T01.
[0007] The top-collected material (high-purity silicon tetrachloride) from the silicon tetrachloride purification tower T03 is mixed with the top-collected material from the reduction recovery secondary tower T02 and sent to the anti-disproportionation reactor R01. The kettle-collected material is the residual material.
[0008] The feed to the deproportionation reactor R01 is a chlorosilane mixture obtained by mixing the top material of the reduction recovery secondary tower T02 and the top material of the silicon tetrachloride purification tower T03. The product of the deproportionation reactor R01 (a chlorosilane mixture mainly composed of trichlorosilane and silicon tetrachloride) is returned to the reduction recovery primary tower T01 for separation.
[0009] The above-mentioned prior art separation and purification process has the following disadvantages:
[0010] The two reduced recycled materials with different temperatures and different contents of dichlorosilane are mixed and then separated again, which increases the operating cost and equipment cost. Utility Model Content
[0011] In view of this, the utility model provides a distillation system for reducing and recovering materials, the main purpose of which is to reduce the operating cost and equipment cost of the separation and purification process.
[0012] In order to achieve the above purpose, the utility model mainly provides the following technical solutions:
[0013] The utility model provides a distillation system for reduction recovery materials, comprising: a reduction recovery material storage tank, an anti-disproportionation reactor, a reduction recovery distillation tower and a silicon tetrachloride purification tower;
[0014] The inlet of the reduction recovery material storage tank is connected to the high-temperature material pipeline of the tail gas recovery section;
[0015] The feed pipe of the silicon tetrachloride purification tower is connected to the bottom of the reduction recovery distillation tower;
[0016] Among them, the outlet of the reduction recovery material storage tank and the outlet of the anti-disproportionation reactor are respectively connected to the feed inlet of the reduction recovery distillation tower, the top production pipeline of the reduction recovery distillation tower is connected to the trichlorosilane storage tank, and the low-temperature material pipeline of the tail gas recovery section and the top production pipeline of the silicon tetrachloride purification tower are respectively connected to the inlet of the anti-disproportionation reactor.
[0017] The purpose of the utility model and the solution to its technical problems can also be further achieved by adopting the following technical measures.
[0018] Optionally, a heat exchanger is also included, and the heat exchanger is installed in the low-temperature material pipeline of the tail gas recovery section.
[0019] Optionally, a residue discharge pipeline is also included, and the residue discharge pipeline is connected to the bottom of the silicon tetrachloride purification tower.
[0020] By means of the above technical solution, the utility model has at least the following advantages:
[0021] The low-temperature material (dichlorosilane content is about 50wt%) of the tail gas recovery section and the purified silicon tetrachloride material enter the anti-disproportionation reactor to generate trichlorosilane. The anti-disproportionation reactor outputs trichlorosilane and surplus silicon tetrachloride to the reduction recovery distillation tower. At the same time, the reduction recovery material storage tank outputs the high-temperature material (dichlorosilane content is about 10wt%) of the tail gas recovery section to the reduction recovery distillation tower, so that the multi-component mixture is gathered in the reduction recovery distillation tower.
[0022] In the reduction recovery distillation tower, silicon tetrachloride as a heavy component is concentrated in the tower bottom and transported to the silicon tetrachloride purification tower, while dichlorosilane and trichlorosilane as light components enter the trichlorosilane storage tank through the top extraction pipeline. Because most of the dichlorosilane is consumed in the anti-disproportionation reactor, the content of dichlorosilane distilled from the top extraction pipeline is relatively small, so that the concentration of dichlorosilane in the trichlorosilane storage tank is reduced to about 5wt%, so that the material ratio in the trichlorosilane storage tank is beneficial to the chemical deposition reaction in the reduction furnace.
[0023] Through the above process, the two reduced recycled materials with different contents of dichlorosilane produced in the tail gas recovery section are treated separately, which reduces the operating cost, reduces one distillation tower compared with the prior art, and reduces the equipment cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a structural schematic diagram of a reduction recovery material separation and purification device in the prior art;
[0025] Figure 2 A schematic structural diagram of a distillation system for reducing and recovering materials provided in an embodiment of the utility model.
[0026] The figure marks in the drawings of the specification include: reduction recovery material storage tank 1, anti-disproportionation reactor 2, reduction recovery distillation tower 3, silicon tetrachloride purification tower 4, high temperature material pipeline 5, trichlorosilane storage tank 6, low temperature material pipeline 7, heat exchanger 8, and residual discharge pipeline 9. DETAILED DESCRIPTION
[0027] 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.
[0028] The utility model is further described in detail below in conjunction with the accompanying drawings and embodiments.
[0029] like Figure 2 As shown, an embodiment of the utility model provides a distillation system for reduction recovery material, which comprises: a reduction recovery material storage tank 1, an anti-disproportionation reactor 2, a reduction recovery distillation tower 3 and a silicon tetrachloride purification tower 4;
[0030] The inlet of the reduction recovery material storage tank 1 is connected to the high-temperature material pipeline 5 of the tail gas recovery section;
[0031] The feed pipe of the silicon tetrachloride purification tower 4 is connected to the bottom of the reduction recovery distillation tower 3;
[0032] Among them, the outlet of the reduction recovery material storage tank 1 and the outlet of the anti-disproportionation reactor 2 are respectively connected to the feed port of the reduction recovery distillation tower 3, the top extraction pipeline of the reduction recovery distillation tower 3 is connected to the trichlorosilane storage tank 6, and the low-temperature material pipeline 7 of the tail gas recovery section and the top extraction pipeline of the silicon tetrachloride purification tower 4 are respectively connected to the inlet of the anti-disproportionation reactor 2.
[0033] The working process of the distillation system for reducing and recovering materials is as follows:
[0034] The low-temperature material (with a relatively high content of dichlorosilane, about 50 wt%) of the tail gas recovery section and the purified silicon tetrachloride material enter the anti-disproportionation reactor 2 to generate trichlorosilane. The anti-disproportionation reactor 2 outputs trichlorosilane and surplus silicon tetrachloride to the reduction recovery distillation tower 3. At the same time, the reduction recovery material storage tank 1 outputs the high-temperature material (with a relatively low content of dichlorosilane, about 10 wt%) of the tail gas recovery section to the reduction recovery distillation tower 3, so that the multi-component mixture is gathered in the reduction recovery distillation tower 3.
[0035] In the reduction recovery distillation tower 3, silicon tetrachloride as a heavy component is concentrated in the tower bottom and is transported to the silicon tetrachloride purification tower 4, while dichlorosilane and trichlorosilane as light components enter the trichlorosilane storage tank 6 through the top extraction pipeline. Since most of the dichlorosilane is consumed in the anti-disproportionation reactor 2, the content of dichlorosilane distilled from the top extraction pipeline is relatively small, so that the concentration of dichlorosilane in the trichlorosilane storage tank 6 is reduced to a reasonable range, about 5wt%. The material ratio in the trichlorosilane storage tank 6 (i.e., the ratio of dichlorosilane and trichlorosilane) is beneficial to the chemical deposition reaction in the reduction furnace.
[0036] In the technical solution of the utility model, through the above process, the two streams of reduced silicon dichloride recovery materials with different contents produced in the tail gas recovery section are treated separately, which reduces the operating cost, reduces one distillation tower compared with the prior art, and reduces the equipment cost.
[0037] Specifically, after the two streams of reduction recovery materials are treated separately, the content of dichlorosilane directly entering the reduction recovery distillation tower 3 is reduced, and the dichlorosilane in the top material of the reduction recovery distillation tower 3 does not need to be further separated before being mixed with high-purity trichlorosilane, thereby reducing one distillation tower and reducing equipment costs.
[0038] like Figure 2 As shown, in a specific implementation, a heat exchanger 8 is also included, and the heat exchanger 8 is installed on the low-temperature material pipeline 7 of the tail gas recovery section.
[0039] In this embodiment, specifically, the temperature of the low-temperature material in the tail gas recovery section is increased by the heat medium of the heat exchanger 8, and the dichlorosilane in the low-temperature material and the purified silicon tetrachloride are mixed and enter the anti-disproportionation reactor 2 to promote the forward anti-disproportionation reaction and improve the yield of trichlorosilane.
[0040] like Figure 2 As shown, in a specific embodiment, it also includes a residue discharge pipeline 9, and the residue discharge pipeline 9 is connected to the bottom of the silicon tetrachloride purification tower 4.
[0041] In this embodiment, specifically, the heavy component materials in the bottom of the silicon tetrachloride purification tower 4 can reach the cold hydrogenation section through the residual discharge pipeline 9.
[0042] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.
Claims
1. A distillation system for reducing and recovering materials, characterized in that: include: A reduction recovery material storage tank, wherein the inlet of the reduction recovery material storage tank is connected to the high-temperature material pipeline of the tail gas recovery section; Anti-disproportionation reactor; Reduction recovery distillation tower; A silicon tetrachloride purification tower, wherein a feed pipe of the silicon tetrachloride purification tower is connected to the bottom of the reduction recovery distillation tower; Among them, the outlet of the reduction recovery material storage tank and the outlet of the anti-disproportionation reactor are respectively connected to the feed inlet of the reduction recovery distillation tower, the top production pipeline of the reduction recovery distillation tower is connected to the trichlorosilane storage tank, and the low-temperature material pipeline of the tail gas recovery section and the top production pipeline of the silicon tetrachloride purification tower are respectively connected to the inlet of the anti-disproportionation reactor.
2. The distillation system for reducing and recovering materials according to claim 1, characterized in that: It also includes a heat exchanger, which is installed on the low-temperature material pipeline of the tail gas recovery section.
3. The distillation system for reducing and recovering materials according to claim 1, characterized in that: It also includes a residue discharge pipeline, which is connected to the bottom of the silicon tetrachloride purification tower.