A diaphragm coupling process for the reduction of recovered chlorosilane separation and purification

Abstract

The application discloses a kind of for reducing recovery chlorosilane separation and purification baffle coupling process, including two baffle rectifying column, heat exchanger and auxiliary equipment.The application is separated by two series and coupled baffle rectifying column, not only realizes the efficient separation of reducing recovery chlorosilane component, but also purifies product, meets the production requirement of large-scale reduction furnace and electronic grade polysilicon, compared with existing process, significantly improve separation efficiency, reduce impurity purity, and greatly reduce the energy consumption of separation system, with excellent industrial application advantage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chlorosilane separation, and particularly relates to a baffle coupling process for reducing and recycling chlorosilane separation and purification. BACKGROUND

[0002] Polysilicon is a basic raw material for the photovoltaic industry and the semiconductor industry. At present, the main production process of polysilicon is the modified Siemens method. First, metallurgical silicon is reacted with hydrogen chloride to synthesize trichlorosilane crude product, then the trichlorosilane crude product is purified by rectification to obtain high-purity trichlorosilane, then the high-purity trichlorosilane is converted into high-purity polysilicon through a reduction reaction and chemical vapor deposition (CVD), the tail gas produced after reduction is recovered by a dry method, the recovered hydrogen is returned to the reduction process, and the recovered liquid chlorosilane is sent to a rectification device for component separation of chlorosilane, the high-purity trichlorosilane separated and obtained is returned to the reduction process, the silicon tetrachloride is sent to a cold hydrogenation process to prepare trichlorosilane, and the dichlorodisilane is also sent to the rectification process after reacting with the silicon tetrachloride to generate trichlorosilane. The modified Siemens method realizes closed-loop utilization of hydrogen and chlorosilane, and has the advantages of maturity, good safety performance, and easy expansion.

[0003] In the hydrogen reduction process of trichlorosilane, the conversion rate of trichlorosilane is only about 10%, resulting in a large amount of unreacted trichlorosilane in the reduction tail gas, and a large amount of energy consumption is inevitably required in the recovery process. In addition to byproduct silicon tetrachloride and dichlorodisilane, the reduction reaction process also generates polymerized chlorosilanes such as hexachloroethane silane with a higher boiling point than silicon tetrachloride, and light impurities with a lower boiling point than dichlorodisilane and heavy impurities with a boiling point between that of trichlorosilane and silicon tetrachloride. Therefore, the separation and purification process of reduction and recovery of chlorosilane is very important, and is related to the quality of polysilicon products.

[0004] Patent CN105366681B discloses a method and device for processing chlorosilane recovered in the production of polysilicon by reduction, and a method and system for processing chlorosilane in the production of polysilicon, which comprises three rectification towers and auxiliary equipment connected thereto. The device can only perform simple component separation, and the product is not refined, resulting in very low product purity and being unable to meet the increasingly high quality demand of the market for polysilicon.

[0005] Patent CN209411790U discloses a rectification energy-saving device for reducing and purifying chlorosilane, which adopts a rectification process composed of three rectification towers, two of which are in a series tower structure. However, this process has a very complex flow process, and the separated silicon tetrachloride does not remove high-boiling substances, and the trichlorosilane product does not remove light impurities and heavy impurities, resulting in the disadvantages of low purity of the separated and recovered product and no application value. SUMMARY

[0006] To solve the above problems, the application provides a kind of baffle coupling process for the separation and purification of reduction recovery chlorosilane, which uses the separation and purification process integrated by baffle rectification and thermal coupling to separate and purify the components of reduction recovery chlorosilane, comprising the following steps:

[0007] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0008] A kind of baffle coupling process for the separation and purification of reduction recovery chlorosilane, which uses the separation and purification process integrated by baffle rectification and thermal coupling to separate and purify the components of reduction recovery chlorosilane, comprising the following steps:

[0009] Step one: reduction recovery chlorosilane enters from the middle upper part of the baffle feed side of baffle rectification column one. The gas phase rising on both sides of the baffle rectification column one converges in the common rectification section above the baffle, the liquid phase descending on both sides of the baffle converges in the common stripping section at the bottom of the baffle, and the liquid phase at the bottom of the common rectification section is distributed to both sides of the baffle according to the product requirements in a mass ratio of 0.3:1 to 1.2:1. Trichlorosilane and dichlorodisilane with silicon tetrachloride content <50 ppm are obtained from the top of the baffle rectification column one, trichlorosilane with trichlorosilane content <50 ppm and high boiling substance (Si2Cl6) with high boiling substance content <0.1 ppm are obtained from the middle lower part of the baffle extraction side of the baffle rectification column one, and high boiling substance with boiling point higher than that of silicon tetrachloride is discharged from the column bottom of the baffle rectification column one.

[0010] Step two: trichlorosilane and dichlorodisilane obtained from the top of the baffle rectification column one enter from the middle upper part of the baffle feed side of baffle rectification column two. The gas phase rising on both sides of the baffle rectification column two converges in the common rectification section above the baffle, the liquid phase descending on both sides of the baffle converges in the common stripping section at the bottom of the baffle, and the liquid phase at the bottom of the common rectification section is distributed to both sides of the baffle according to the product requirements in a mass ratio of 0.1:1 to 1:1. Light impurities are discharged from the top of the baffle rectification column two, dichlorodisilane with light impurity content <15 ppm is obtained from the side of the common rectification section of the baffle rectification column two, high-purity trichlorosilane with heavy impurity content <1.0 ppm is obtained from the middle lower part of the baffle extraction side of the baffle rectification column two, and heavy impurities are discharged from the column bottom of the baffle rectification column two.

[0011] The application also provides a kind of baffle coupling system for the separation and purification of reduction recovery chlorosilane, comprising: baffle rectification column one, baffle rectification column two, baffle rectification column one reboiler, baffle rectification column one condenser, baffle rectification column two reboiler and baffle rectification column two condenser.

[0012] The vertical baffle is arranged in the column of the one-stage column of the baffle rectification, and the one-stage column of the baffle rectification is divided into a common rectification section, a baffle feeding side, a baffle discharge side and a common stripping section.

[0013] The vertical baffle is arranged in the column of the two-stage column of the baffle rectification, and the two-stage column of the baffle rectification is divided into a common rectification section, a baffle feeding side, a baffle discharge side and a common stripping section.

[0014] The gas phase outlet of the one-stage column of the baffle rectification is connected with the shell phase gas inlet of the condenser of the one-stage column of the baffle rectification and the shell phase gas inlet of the reboiler of the two-stage column of the baffle rectification respectively, the shell phase liquid outlet of the condenser of the one-stage column of the baffle rectification and the shell phase liquid outlet of the reboiler of the two-stage column of the baffle rectification are combined and then connected with the reflux port of the one-stage column of the baffle rectification, the silicon tetrachloride and dichlorosilane removal pipeline and the trichlorosilane and high-boiling substance removal pipeline respectively.

[0015] The feeding port is arranged in the middle upper part of the baffle feeding side of the one-stage column of the baffle rectification and connected with the reduced chlorosilane recovery pipeline, and the silicon tetrachloride discharge port is arranged in the middle lower part of the baffle discharge side and connected with the trichlorosilane and high-boiling substance removal pipeline.

[0016] The liquid phase inlet of the reboiler of the one-stage column of the baffle rectification is connected with the column sump, the gas phase outlet of the reboiler is connected with the gas phase inlet of the column sump, and the liquid phase outlet of the column sump is connected with the high-boiling substance discharge pipeline.

[0017] The gas phase outlet of the two-stage column of the baffle rectification is connected with the shell phase gas inlet of the condenser of the two-stage column of the baffle rectification, and the shell phase liquid outlet of the condenser of the two-stage column of the baffle rectification is connected with the reflux port of the two-stage column of the baffle rectification and the light impurity discharge pipeline respectively.

[0018] The feeding port is arranged in the middle upper part of the baffle feeding side of the two-stage column of the baffle rectification and connected with the trichlorosilane and dichlorosilane removal pipeline, the liquid phase dichlorosilane discharge port is arranged in the middle part of the common rectification section and connected with the dichlorosilane discharge pipeline, and the high-purity trichlorosilane discharge port is arranged in the middle lower part of the baffle discharge side and connected with the high-purity trichlorosilane discharge pipeline.

[0019] The liquid phase inlet of the reboiler of the two-stage column of the baffle rectification is connected with the column sump, the gas phase outlet of the reboiler is connected with the gas phase inlet of the column sump, and the liquid phase outlet of the column sump is connected with the heavy impurity discharge pipeline.

[0020] Preferably, the number of theoretical plates of the common rectification section of the one-stage column of the baffle rectification is 35-55, the number of theoretical plates of the baffle feeding side is 60-80, the number of theoretical plates of the baffle discharge side is 60-80, and the number of theoretical plates of the common stripping section is 10-30.

[0021] Preferably, the number of theoretical plates of the common rectification section of the dividing wall rectification one-tower is 35-55, the number of theoretical plates of the dividing wall feed side is 50-70, the number of theoretical plates of the dividing wall production side is 50-70, and the number of theoretical plates of the common stripping section is 10-30.

[0022] Preferably, the top pressure of the dividing wall rectification one-tower is 0.6-0.8 MPaG, the top temperature is 90-110℃, and the reflux ratio is 1.5:1-3:1.

[0023] Preferably, the top pressure of the dividing wall rectification two-tower is 0.2-0.4 MPaG, the top temperature is 40-60℃, and the reflux ratio is 250:1-350:1.

[0024] Compared with the prior art, the present application has the following advantages and technical effects:

[0025] The present application provides a dividing wall coupled process for reducing and recycling chlorosilane separation and purification, which uses a separation and purification process integrated by dividing wall rectification and heat coupling technology, not only realizes efficient separation of reduced and recycled chlorosilane, but also purifies the product, meeting the production requirements of large-scale reduction furnaces and electronic-grade polysilicon. Compared with the prior art, the separation efficiency is significantly improved, the impurity purity is reduced, the impurity content of single chlorosilane product is reduced by more than 80%, and the energy consumption of the device is also reduced by more than 30%. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments illustrated in the drawings are provided to explain the present application and are not intended to limit the present application. In the drawings:

[0027] Figure 1 The present application provides a dividing wall coupled system for reducing and recycling chlorosilane separation and purification, which uses a separation and purification process integrated by dividing wall rectification and heat coupling technology, not only realizes efficient separation of reduced and recycled chlorosilane, but also purifies the product, meeting the production requirements of large-scale reduction furnaces and electronic-grade polysilicon. Compared with the prior art, the separation efficiency is significantly improved, the impurity purity is reduced, the impurity content of single chlorosilane product is reduced by more than 80%, and the energy consumption of the device is also reduced by more than 30%.

[0028] Figure 2The process flow diagram for Example 1 is shown in Figure 1. In Figure 1, T3 is the first reduced distillation column, T4 is the second reduced distillation column, E5 is the first reduced distillation column reboiler, E6 is the first reduced distillation column condenser, E7 is the second reduced distillation column reboiler, and E8 is the second reduced distillation column condenser. T3-1 is the rectifying section of the first reduced distillation column, T3-2 is the stripping section of the first reduced distillation column, T4-1 is the rectifying section of the second reduced distillation column, and T4-2 is the stripping section of the second reduced distillation column. DETAILED DESCRIPTION

[0029] The following detailed description of various example embodiments of the application will not be considered to limit the application, but rather to provide a more detailed description of certain aspects, features, and embodiments of the application.

[0030] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, the use of the term "about" in relation to a value or a range of values is intended to include each individual intermediate value and each smaller range that falls within the range of values. The upper and lower limits of these smaller ranges can be included or excluded from the range.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All publications mentioned in this specification are herein incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference in this specification is not intended as an admission that the reference is prior art, but rather that the reference is part of the technical literature that is relevant to the disclosure.

[0032] Many modifications and variations of this application can be made in the light of the above teachings without departing from the spirit and scope thereof. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only. It is to be understood that the application is not to be limited by the foregoing examples.

[0033] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having", "contain", "containing", and the like are open-ended terms that are intended to mean "including, but not limited to".

[0034] The terms "first", "second", "T1", "T2", "E1", "E2", "T1-1", "T1-2", "T1-3", "T1-4", and the like are merely used to distinguish descriptions, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", and the like do not mean that the components must be absolutely horizontal or vertical, but can be slightly inclined. As "horizontal" merely means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. The term "vertical" in the present application is perpendicular to the ground direction.

[0035] In the description of the present application, it should be further explained that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, can be fixedly connected, can also be detachably connected, or integrally connected; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] The raw materials used in the embodiments of the present application are all commercially available.

[0037] The present application provides a kind of for reducing recovery chlorosilane separation and purification baffle coupling process, process flow chart as Figure 1 As described above, the baffle coupling system includes a baffle rectification column T1, a baffle rectification column T2, a baffle rectification column reboiler E1, a baffle rectification column condenser E2, a baffle rectification column reboiler E3 and a baffle rectification column condenser E4.

[0038] The baffle rectification column T1 is provided with a vertical baffle in the column, which divides the baffle rectification column T1 into a common rectification section T1-1, a baffle feed side T1-2, a baffle production side T1-3 and a common stripping section T1-4.

[0039] The gas phase outlet at the top of the baffle rectification column T1 is connected to the shell side gas phase inlet of the baffle rectification column condenser E2 and the shell side gas phase inlet of the baffle rectification column reboiler E3, respectively. The shell side liquid phase outlet of the baffle rectification column condenser E2 and the shell side liquid phase outlet of the baffle rectification column reboiler E3 are combined and connected to the reflux port at the top of the baffle rectification column T1, the pipeline for removing silicon tetrachloride, and the pipeline for removing silicon tetrachloride.

[0040] The upper part of the baffle feed side T1-2 of the baffle rectification column T1 is provided with a feed port connected to the pipeline for reducing recovery chlorosilane, and the lower part of the baffle production side T1-3 is provided with a silicon tetrachloride outlet connected to the pipeline for removing silicon tetrachloride and high-boiling substances.

[0041] The liquid phase inlet of the reboiler E1 of the partition rectification one-column T1 is connected with the column still, the gas phase outlet of the reboiler E1 is connected with the gas phase inlet of the column still, and the liquid phase outlet of the column still is connected with the heavy component outlet pipeline.

[0042] The bottom of the common rectification section T1-1 of the partition rectification one-column T1 is provided with a liquid collection and redistribution device, and the liquid is distributed to both sides of the partition according to the product demand at a mass ratio of 0.3:1 to 1.2:1.

[0043] The partition rectification two-column T2 is provided with a vertical partition inside the column, and the partition rectification two-column T2 is divided into a common rectification section T2-1, a partition feeding side T2-2, a partition production side T2-3 and a common rectification section T2-4.

[0044] The gas phase outlet at the top of the partition rectification two-column T2 is connected with the shell side gas phase inlet of the condenser E4 of the partition rectification two-column T2, and the shell side liquid phase outlet of the condenser E4 of the partition rectification two-column T2 is connected with the column top reflux port and the light component outlet pipeline of the partition rectification two-column T2, respectively.

[0045] The upper part of the partition feeding side T2-2 of the partition rectification two-column T2 is provided with a feeding port, which is connected with the silicon tetrachloride removal trichlorosilane and dichlorodisilane outlet pipeline; the middle part of the common rectification section T2-1 is provided with a dichlorodisilane production port, which is connected with the dichlorodisilane outlet pipeline; and the lower part of the partition production side T2-3 is provided with a high-purity trichlorosilane production port, which is connected with the high-purity trichlorosilane outlet pipeline.

[0046] The liquid phase inlet of the reboiler E3 of the partition rectification two-column T2 is connected with the column still, the gas phase outlet of the reboiler E3 is connected with the gas phase inlet of the column still, and the liquid phase outlet of the column still is connected with the heavy component outlet pipeline.

[0047] The bottom of the common rectification section T2-1 of the partition rectification two-column T2 is provided with a liquid collection and redistribution device, and the liquid is distributed to both sides of the partition according to the product demand at a mass ratio of 0.1:1 to 1:1.

[0048] In some embodiments of the present application, the number of theoretical plates of the common rectification section T1-1 of the partition rectification one-column T1 is 35 to 55, the number of theoretical plates of the partition feeding side T1-2 is 60 to 80, the number of theoretical plates of the partition production side T1-3 is 60 to 80, and the number of theoretical plates of the common rectification section T1-4 is 10 to 30. The partition inside the partition rectification one-column T1 can be centrally arranged or eccentrically arranged, and is determined according to the raw material composition and separation index calculation.

[0049] In some embodiments of the present application, the number of theoretical plates of the common rectification section T2-1 of the partitioned rectification two-column T2 is 35-55, the number of theoretical plates of the partitioned feed side T2-2 is 50-70, the number of theoretical plates of the partitioned production side T2-3 is 50-70, and the number of theoretical plates of the common stripping section T2-4 is 10-30. The partition within the partitioned rectification two-column T2 can be centrally arranged or eccentrically arranged, which is determined according to the composition of the raw material and the separation index calculation.

[0050] In some embodiments of the present application, the top pressure of the partitioned rectification one-column (T1) is 0.6-0.8 MPaG, the top temperature is 90-110℃, and the reflux ratio is 1.5:1-3:1.

[0051] In some embodiments of the present application, the top pressure of the partitioned rectification two-column (T2) is 0.2-0.4 MPaG, the top temperature is 40-60℃, and the reflux ratio is 250:1-350:1.

[0052] The technical solutions of the present application are further illustrated by the following examples.

[0053] Example 1

[0054] This example accounts for the treatment of 410892 kg / h of reduced and recovered chlorosilane.

[0055] According to the process flow of Figure 1 , the separation and purification of reduced and recovered chlorosilane is carried out, and the partitioned coupling system for the separation and purification of reduced and recovered chlorosilane includes a partitioned rectification one-column T1, a partitioned rectification two-column T2, a partitioned rectification one-column reboiler E1 (which is a thermosyphon reboiler with saturated steam at 0.5 MPaG as heat source), a partitioned rectification one-column condenser E2 (which is a condenser with circulating water as condensing medium), a partitioned rectification two-column reboiler E3, and a partitioned rectification two-column condenser E4 (which is a condenser with circulating water as condensing medium); the top pressure of the partitioned rectification one-column T1 is 0.63 MPaG, the top temperature is 101.2℃, the top reflux ratio is 2.2:1, and the material temperature controlled by the partitioned rectification one-column condenser E2 is 90℃; the top pressure of the partitioned rectification two-column T2 is 0.35 MPaG, the top temperature is 55.9℃, the top reflux ratio is 299:1, and the material temperature controlled by the partitioned rectification two-column condenser E4 is 46℃.

[0056] The middle part of the one-column partition rectification tower T1 is provided with a vertical partition plate, so that the one-column partition rectification tower T1 is divided into a common rectification section T1-1, a partition plate feeding side T1-2, a partition plate recovery side T1-3 and a common stripping section T1-4; the common rectification section T1-1, the partition plate feeding side T1-2, the partition plate recovery side T1-3 and the common stripping section T1-4 are filled with separation elements in the form of regular packing-tray combination, the theoretical plate number of the common rectification section T1-1 is 45, the theoretical plate number of the partition plate feeding side T1-2 is 75, the theoretical plate number of the partition plate recovery side T1-3 is 75, and the theoretical plate number of the common stripping section T1-4 is 15.

[0057] The gas phase outlet of the one-column partition rectification tower T1 is connected with the shell side gas phase inlet of the condenser E2 of the one-column partition rectification tower T1 and the shell side gas phase inlet of the reboiler E3 of the two-column partition rectification tower T2, respectively; the shell side liquid phase outlet of the condenser E2 of the one-column partition rectification tower T1 and the shell side liquid phase outlet of the reboiler E3 of the two-column partition rectification tower T2 are combined and then connected with the tower top reflux port of the one-column partition rectification tower T1, a trichlorosilane and dichlorosilane removal pipeline and a silicon tetrachloride removal pipeline, respectively.

[0058] The theoretical plate number 6 of the partition plate feeding side T1-2 of the one-column partition rectification tower T1 is provided with a feeding port connected with a reduced chlorosilane recovery pipeline; the theoretical plate number 61 of the partition plate recovery side T1-3 is provided with a silicon tetrachloride recovery outlet connected with a trichlorosilane and high-boiling substance removal pipeline.

[0059] The liquid phase inlet of the reboiler E1 of the one-column partition rectification tower T1 is connected with the tower bottom, the gas phase outlet of the reboiler E1 is connected with the gas phase inlet of the tower bottom, and the liquid phase outlet of the tower bottom is connected with a high-boiling substance removal pipeline.

[0060] The bottom of the common rectification section T1-1 of the one-column partition rectification tower T1 is provided with a liquid collection and redistribution device, and the liquid is distributed to the partition plate feeding side and the partition plate recovery side according to the product demand in a mass ratio of 0.53:1.

[0061] The two-column partition rectification tower T2 is provided with a vertical partition plate, so that the two-column partition rectification tower T2 is divided into a common rectification section T2-1, a partition plate feeding side T2-2, a partition plate recovery side T2-3 and a common stripping section T2-4; the common rectification section T2-1, the partition plate feeding side T2-2, the partition plate recovery side T2-3 and the common stripping section T2-4 are filled with separation elements in the form of regular packing-tray combination, the theoretical plate number of the common rectification section T2-1 is 45, the theoretical plate number of the partition plate feeding side T2-2 is 60, the theoretical plate number of the partition plate recovery side T2-3 is 60, and the theoretical plate number of the common stripping section T2-4 is 15.

[0062] The overhead vapor phase outlet of the said dividing wall distillation two-column T2 is connected with the shell phase vapor inlet of the condenser E4 of the dividing wall distillation two-column T2, and the shell phase liquid outlet of the condenser E4 of the dividing wall distillation two-column T2 is connected with the overhead reflux port of the dividing wall distillation two-column T2 and the light impurity outlet pipeline respectively.

[0063] The theoretical plate number of the dividing wall feed side T2-2 of the said dividing wall distillation two-column T2 is 31, and a feed port is arranged at the position, which is connected with the silicon tetrachloride removal trichlorosilane and dichlorodisilane outlet pipeline; the theoretical plate number of the common distillation section T2-1 is 16, and a dichlorodisilane sampling outlet is arranged at the position, which is connected with the dichlorodisilane outlet pipeline; the theoretical plate number of the dividing wall sampling side T2-3 is 46, and a high-purity trichlorosilane sampling outlet is arranged at the position, which is connected with the high-purity trichlorosilane outlet pipeline.

[0064] The liquid phase inlet of the reboiler E3 of the said dividing wall distillation two-column T2 is connected with the column bottom, the vapor phase outlet of the reboiler E3 is connected with the vapor phase inlet of the column bottom, and the liquid phase outlet of the column bottom is connected with the heavy impurity outlet pipeline.

[0065] The bottom of the common distillation section T2-1 of the said dividing wall distillation two-column T2 is provided with a liquid collection and redistribution device, and the liquid is distributed to the dividing wall feed side and the dividing wall sampling side according to the product demand in a mass ratio of 0.137:1.

[0066] The reduced chlorosilane with a pressure of 0.9 MPaG and a temperature of 80°C is introduced from the feed port of the dividing wall feed side T1-2 of the dividing wall distillation one-column T1, and the calculation results are as follows according to the above-mentioned suitable column structure and optimized operation conditions:

[0067] The heating capacity of the reboiler E1 of the said dividing wall distillation one-column T1 is 39124kw;

[0068] The energy consumption of the condenser E2 of the said dividing wall distillation one-column T1 is -17291kw, the energy consumption of the condenser E4 of the dividing wall distillation two-column T2 is -19266kw, and the total cold load is -36557kw.

[0069] The material balance table of the embodiment is shown in Table 1.

[0070]

[0071] Comparative Example 1

[0072] According to the above-mentioned suitable column structure and optimized operation conditions, the calculation results are as follows: Figure 2The process flow of the application is subjected to conventional reduction recovery chlorosilane separation and purification, and the conventional reduction recovery chlorosilane separation and purification device comprises a reduction rectification column T3, a reduction rectification column T4, a reboiler E5 of the reduction rectification column T3 (a thermosyphon reboiler taking saturated steam at 0.5 MPaG as heat source), a condenser E6 of the reduction rectification column T3 (a condenser taking circulating water as condensing medium), a reboiler E7 of the reduction rectification column T4 (a thermosyphon reboiler taking saturated steam at 0.2 MPaG as heat source), and a condenser E8 of the reduction rectification column T4 (a condenser taking circulating water as condensing medium). The top pressure of the reduction rectification column T3 is 0.63 MPaG, the top temperature is 101.2℃, the top reflux ratio is 2.2:1, and the material temperature controlled by the condenser E6 of the reduction rectification column T3 is 90℃. The top pressure of the reduction rectification column T4 is 0.35 MPaG, the top temperature is 55.9℃, the top reflux ratio is 299:1, and the material temperature controlled by the condenser E8 of the reduction rectification column T4 is 46℃.

[0073] The reduction rectification column T3 is divided into a reduction rectification column rectification section T3-1 and a reduction rectification column stripping section T3-2, and the rectification section T3-1 and the stripping section T3-2 are filled with separation elements in the form of regular packing-tray combination. The theoretical plate number of the rectification section T3-1 is 60, and the theoretical plate number of the stripping section T3-2 is 75.

[0074] The gas phase outlet of the top of the reduction rectification column T3 is connected with the gas phase inlet of the shell side of the condenser E6 of the reduction rectification column T3, and the liquid phase outlet of the shell side of the condenser E6 of the reduction rectification column T3 is connected with the top reflux port of the reduction rectification column T3, the trichlorosilane and dichlorodisilane removal pipeline of silicon tetrachloride.

[0075] The theoretical plate number of the reduction rectification column stripping section T3-2 of the reduction rectification column T3 is provided with a silicon tetrachloride outlet at a position of 46, which is connected with the trichlorosilane and high-boiling substance removal pipeline of silicon tetrachloride.

[0076] The liquid phase inlet of the reboiler E5 of the reduction rectification column T3 is connected with the column still, the gas phase outlet of the reboiler E5 is connected with the gas phase inlet of the column still, and the liquid phase outlet of the column still is connected with the high-boiling substance removal pipeline.

[0077] The liquid phase inlet of the reboiler E1 of the baffle rectification column T1 is connected with the column still, the gas phase outlet of the reboiler E1 is connected with the gas phase inlet of the column still, and the liquid phase outlet of the column still is connected with the high-boiling substance removal pipeline.

[0078] The reducing rectification two-tower T4 is divided into a reducing rectification two-tower rectification section T4-1 and a reducing rectification two-tower stripping section T4-2, the rectification section T3-1 and the stripping section T3-2 are filled with regular packing-tray combined separation elements, the theoretical plate number of the rectification section T4-1 is 60, and the theoretical plate number of the stripping section T4-2 is 60;

[0079] The tower top gas phase outlet of the reducing rectification two-tower T4 is connected with the shell phase gas phase inlet of the reducing rectification two-tower T4 condenser E8, and the shell phase liquid phase outlet of the reducing rectification two-tower T4 condenser E8 is connected with the reducing rectification two-tower T4 tower top reflux port and the dichlorodihydrogen silicon discharge pipeline, respectively.

[0080] The theoretical plate number 46 of the stripping section T4-2 of the reducing rectification two-tower T4 is provided with a high-purity trichlorosilane sampling outlet connected with a high-purity trichlorosilane discharge pipeline.

[0081] The liquid phase inlet of the reducing rectification two-tower T4 reboiler E7 is connected with the tower pot, the gas phase outlet of the reboiler E7 is connected with the gas phase inlet of the tower pot, and the liquid phase outlet of the tower pot is connected with a heavy impurity discharge pipeline.

[0082] The reducing recovery chlorosilane with a pressure of 0.9 MPaG and a temperature of 80 DEG C is introduced from the feed inlet of the rectification section bottom T3-1 of the reducing rectification one-tower T3, and the calculation results are as follows under the same operation conditions as those in example 1 according to the above suitable tower structure:

[0083] The heating capacity of the reboiler E5 of the reducing rectification one-tower T3 is 39122kw, the heating capacity of the reboiler E7 of the reducing rectification two-tower T4 is 18661kw, and the total heat load is 57783kw;

[0084] The energy consumption of the condenser E6 of the reducing rectification one-tower T3 is -35957kw, the energy consumption of the condenser E8 of the reducing rectification two-tower T4 is -19266kw, and the total cold load is -55223kw.

[0085] The material balance table of the example is shown in Table 1.

[0086]

[0087] The comparison of example 1 and comparative example 1 is shown in Tables 3-4:

[0088] Table 3 Product comparison of example 1 and comparative example 1

[0089] Comparative Example 1 Example 1 Comparative Example 1 Impurity reduction ratio ppm of Si2Cl6 in silicon tetrachloride ＜0.1 56.8 99.0％ Light impurity content in dichlorodihydrogen silicon, ppm 10.3 163 93.7％ Heavy impurity content in trichlorohydrogen silicon, ppm 0.8 6.0 86.7％

[0090] Table 4 Energy consumption comparison of example 1 and comparative example 1

[0091] Comparative Example 1 Example 1 Comparative Example 1 Energy saving ratio Thermal load, kw 39124 57783 32.3％ Cooling load, kw 36557 55223 33.8％

[0092] As can be found by comparing Table 3 and Table 4, thanks to the separation and purification process integrated with the baffle rectification and heat coupling technology, not only the high-efficiency separation of chlorosilane recovered by reduction is realized, but also the products are purified to meet the production requirements of large-scale reduction furnace and electronic-grade polysilicon. The baffle reaction rectification process coupled with the reaction rectification and baffle rectification technologies, the process presented by the present application has higher separation efficiency, less impurity content of products and lower energy consumption compared with the two-tower process using conventional rectification.

[0093] Finally, it should be noted that the above is only the preferred embodiment of the present application, rather than limiting it; although the content of the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the content of the present application.

Claims

1. A diaphragm coupled process for the reduction of the separation and purification of chlorosilane recovered, characterized in that, Comprising the following steps: The reduced chlorosilane is fed from the upper part of the baffle feed side (T1-2) of the first baffle rectification column (T1), the silicon trichloride and dichlorodisilane removed at the top of the column, the silicon tetrachloride removed at the lower part of the baffle discharge side (T1-3), and the high-boiling residue discharged from the column bottom; The silicon trichloride and dichlorodisilane removed at the top of the first baffle rectification column (T1) are fed from the upper part of the baffle feed side (T2-2) of the second baffle rectification column (T2), the light impurities are discharged from the top of the second baffle rectification column (T2), the dichlorodisilane is discharged from the middle side of the middle part of the common rectification section (T2-1), the high-purity silicon trichloride is discharged from the lower part of the baffle discharge side (T2-3), and the heavy impurities are discharged from the column bottom; The gas phase outlet at the top of the first baffle rectification column (T1) is connected to the gas phase inlet of the condenser (E2) of the first baffle rectification column (T1) and the gas phase inlet of the reboiler (E3) of the second baffle rectification column (T2), respectively, the liquid phase outlet of the condenser (E2) of the first baffle rectification column (T1) and the liquid phase outlet of the reboiler (E3) of the second baffle rectification column (T2) are combined and connected to the top reflux port of the first baffle rectification column (T1) and the silicon trichloride and dichlorodisilane removal pipeline, respectively; The top pressure of the first baffle rectification column (T1) is 0.6-0.8 MPaG, the top temperature is 90-110℃, and the reflux ratio is 1.5:1-3:1; The top pressure of the second baffle rectification column (T2) is 0.2-0.4 MPaG, the top temperature is 40-60℃, and the reflux ratio is 250:1-350:

1.

2. A barrier coupling process for the separation and purification of reduced recycle chlorosilane as claimed in claim 1, wherein: The theoretical plate number of the common rectification section (T1-1) of the first baffle rectification column (T1) is 35-55, the theoretical plate number of the baffle feed side (T1-2) is 60-80, the theoretical plate number of the baffle discharge side (T1-3) is 60-80, and the theoretical plate number of the common stripping section (T1-4) is 10-30.

3. A barrier coupling process for the separation and purification of reduced recycle chlorosilane as claimed in claim 1, wherein: The theoretical plate number of the common rectification section (T2-1) of the second baffle rectification column (T2) is 35-55, the theoretical plate number of the baffle feed side (T2-2) is 50-70, the theoretical plate number of the baffle discharge side (T2-3) is 50-70, and the theoretical plate number of the common stripping section (T2-4) is 10-30.

4. A barrier coupling process for the separation and purification of reduced recycle chlorosilane according to claim 1, characterized in that: The liquid phase inlet of the reboiler (E1) of the first baffle rectification column (T1) is connected to the column bottom, the gas phase outlet of the reboiler (E1) is connected to the gas phase inlet of the column bottom, and the liquid phase outlet of the column bottom is connected to the high-boiling residue removal pipeline.

5. A barrier coupling process for the separation and purification of reduced recycle chlorosilane according to claim 1, characterized in that: The gas phase outlet at the top of the second baffle rectification column (T2) is connected to the shell side gas phase inlet of the condenser (E4) of the second baffle rectification column (T2), the shell side liquid phase outlet of the condenser (E4) of the second baffle rectification column (T2) is connected to the top reflux port of the second baffle rectification column (T2) and the light impurities removal pipeline, respectively; The middle part of the common rectification section (T2-1) of the second baffle rectification column (T2) is provided with a liquid phase side tapping port, which is connected to the dichlorodisilane discharge pipeline; The liquid phase inlet of the reboiler (E1) of the first baffle rectification column (T1) is connected to the column bottom, the gas phase outlet of the reboiler (E1) is connected to the gas phase inlet of the column bottom, and the liquid phase outlet of the column bottom is connected to the high-boiling residue removal pipeline. The liquid phase inlet of the said partition rectification two-tower (T2) reboiler (E3) is connected with the tower kettle, the gas phase outlet of the reboiler (E3) is connected with the gas phase inlet of the tower kettle, and the liquid phase outlet of the tower kettle is connected with the heavy impurity outlet pipeline.

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