A trichlorosilane multi-column differential pressure coupled rectification system and rectification method

Abstract

The application provides a trichlorosilane multi-tower differential pressure coupled rectification system and a rectification method, the trichlorosilane multi-tower differential pressure coupled rectification system comprising a rough separation tower, a light removal tower and a heavy removal tower; the light removal tower comprising a rough distillation first-stage tower and a rectification first-stage tower, and the heavy removal tower comprising a rough distillation second-stage tower; the rough distillation first-stage tower being provided with a first reboiler, and the rough distillation second-stage tower being provided with a second reboiler; the tower top outlet of the rough separation tower being communicated with the second reboiler and then with the raw material inlet of the rough distillation first-stage tower, and the tower top outlet of the rectification first-stage tower being communicated with the first reboiler. The trichlorosilane multi-tower differential pressure coupled rectification system can reduce the reflux ratio of the light removal tower, effectively save the energy consumption in the trichlorosilane rectification process, and reduce the equipment investment and operation cost.

Description

Technical Field

[0001] This invention belongs to the field of distillation technology, and particularly relates to a trichlorosilane multi-tower differential pressure coupled distillation system and distillation method. Background Technology

[0002] In the production of high-purity polysilicon, the Siemens process has long been considered the standard, using chemical vapor deposition (CVD) technology to decompose trichlorosilane into high-purity silicon. However, with the rapid development of the global solar photovoltaic industry, the demand for high-purity polysilicon has increased dramatically, and the high energy consumption and high cost of the traditional Siemens process have gradually become apparent, limiting its economic viability and sustainability in large-scale production.

[0003] A major challenge of the traditional Siemens process lies in the handling of silicon tetrachloride. During the process, silicon tetrachloride is generated in large quantities as a byproduct, and its treatment and disposal not only increase production costs but also impose an environmental burden. Therefore, how to efficiently utilize silicon tetrachloride has become an important issue for improving the economics of the process.

[0004] The core of the improved Siemens process lies in the comprehensive utilization of silicon tetrachloride through cold hydrogenation technology. Cold hydrogenation technology, under high-temperature conditions, utilizes a catalyst to promote the reaction of silicon powder, hydrogen, and silicon tetrachloride, converting silicon tetrachloride into trichlorosilane. This process not only improves the utilization efficiency of silicon tetrachloride and reduces waste emissions but also lowers production costs and increases resource utilization.

[0005] However, the syngas produced during cold hydrogenation contains various components, including the target product trichlorosilane, the byproduct dichlorosilane, and other heavy components (such as methyldichlorosilane). Therefore, effectively separating and purifying trichlorosilane from the syngas becomes the key to the process.

[0006] Figure 1 This is a schematic diagram of a distillation system for trichlorosilane in the prior art. Figure 1As shown, the existing distillation system mainly includes a crude distillation column 1, a primary crude distillation column 2, a secondary crude distillation column 3, a tertiary crude distillation column 4, a primary rectification column 5, a secondary rectification column 6, and a primary reduction column 7. The material to be separated (synthesis liquid) enters the crude distillation column 1 through the feed inlet for crude distillation. The silicon tetrachloride obtained from the side sample of the crude distillation column 1 is returned to the cold hydrogenation reactor. High-boiling-point substances are removed from the bottom of the column to obtain the first intermediate material (mainly including trichlorosilane and dichlorosilane). The first intermediate material is collected from the top of the crude distillation column 1 and enters the primary crude distillation column 2 through the feed inlet for primary crude distillation, whereby the light components (mainly including dichlorosilane) are collected from the top of the primary crude distillation column 2. The process yields a second intermediate material (mainly trichlorosilane and heavy components). This second intermediate material is collected from the bottom of the primary crude distillation column 2 and enters the secondary crude distillation column 3 through the feed inlet for second-stage crude distillation. The heavy components with boiling points higher than trichlorosilane in the second intermediate material are collected from the bottom of the secondary crude distillation column 3, while the light components (mainly trichlorosilane) are collected from the top of the secondary crude distillation column 3, yielding a third intermediate material. This third intermediate material enters the reboiler of the tertiary crude distillation column 4. After providing heat to the reboiler, a portion is refluxed, and the other portion enters the tertiary crude distillation column 4 through the feed inlet for third-stage crude distillation, further separating the third intermediate material. The heavy components in the intermediate material with boiling points higher than trichlorosilane are collected from the bottom of the third intermediate material via the crude distillation three-stage column 4. The remaining fourth intermediate material, mainly containing trichlorosilane, is collected from the top of the crude distillation three-stage column 4. The fourth intermediate material enters the reboiler at the bottom of the crude distillation first-stage column 2. After providing heat to the reboiler, part of it is refluxed, and the other part enters the rectification first-stage column 5 for separation. In the rectification first-stage column 5, the light components of the fourth intermediate material (mainly boron and phosphorus compounds with boiling points between dichlorosilane and trichlorosilane) are collected from the top of the rectification first-stage column 5. The remaining fifth intermediate material, mainly containing trichlorosilane, is collected from the top of the rectification first-stage column 5. The fifth intermediate material is collected from the bottom of the distillation column; it enters the second-stage distillation column 6 through the feed inlet for separation. In the second-stage distillation column 6, the heavy components in the fifth intermediate material are further separated to obtain high-purity trichlorosilane. The first-stage reduction column 7 in the reduction process provides heat to the reboiler of the second-stage distillation column 6, so that the heavy components of the fifth intermediate material are collected from the bottom of the second-stage distillation column 6 and enter the third-stage crude distillation column 4 for further separation to further extract trichlorosilane from the fifth intermediate material. The high-purity trichlorosilane obtained from the second-stage distillation column 6 is collected from the top of the second-stage distillation column 6 and enters the reboiler of the first-stage distillation column 5 to provide heat to the first-stage distillation column 5. Part of it is refluxed and the other part goes to the reduction process.

[0007] In existing distillation systems, the second-stage crude distillation column 3 provides heat to the third-stage crude distillation column 4, the third-stage crude distillation column 4 provides heat to the first-stage crude distillation column 2, the first-stage reduction column 7 provides heat to the second-stage rectification column 6, and the second-stage rectification column 6 provides heat to the first-stage rectification column 5. However, the reflux ratios of the second-stage crude distillation column 3, the third-stage crude distillation column 4, and the second-stage rectification column 6 are 3–5, and the overhead vapor flow rates of the second-stage crude distillation column 3, the third-stage crude distillation column 4, and the second-stage rectification column 6 are relatively large. The overhead vapor from the first-stage crude distillation column 2 is... The material volume is very small. In order to enable the first-stage crude distillation column 2 to utilize the heat from the second-stage crude distillation column 3 and the third-stage crude distillation column 4, and to enable the first-stage rectification column 5 to utilize the heat from the second-stage rectification column 6, the reflux ratio of the first-stage crude distillation column 2 and the first-stage rectification column 5 is usually increased to 50-150, which is much greater than the actual reflux ratio required by the first-stage crude distillation column 2 and the first-stage rectification column 5. This increases the equipment investment and operating costs of the first-stage crude distillation column 2 and the first-stage rectification column 5. Summary of the Invention

[0008] The main objective of this invention is to provide a trichlorosilane multi-tower differential pressure coupling distillation system, which can reduce the reflux ratio of the light-light-removal tower, effectively save energy consumption in the trichlorosilane distillation process, and reduce equipment investment and operating costs.

[0009] The present invention also provides a distillation method for trichlorosilane multi-tower differential pressure coupling, which uses the above-mentioned distillation system. Therefore, this method can reduce the reflux ratio of the light tower and reduce energy consumption.

[0010] In a first aspect, the present invention provides a trichlorosilane multi-tower differential pressure coupled distillation system, comprising a crude distillation tower, a light-light distillation tower, and a heavy-light distillation tower; the light-light distillation tower comprises a primary crude distillation tower and a primary distillation tower, and the heavy-light distillation tower comprises a secondary crude distillation tower.

[0011] The primary crude distillation column has a first reboiler, and the secondary crude distillation column has a second reboiler;

[0012] The top outlet of the crude distillation column is connected to the second reboiler, and then to the feed inlet of the primary crude distillation column. The top outlet of the primary rectification column is connected to the first reboiler.

[0013] The distillation system described above further includes a three-stage crude distillation column and a two-stage rectification column, and the distillation system also includes a first-stage reduction column;

[0014] The crude distillation three-stage column has a third reboiler, and the rectification two-stage column has a fourth reboiler;

[0015] The bottom outlet of the primary crude distillation column is connected to the feed inlet of the secondary crude distillation column; the top outlet of the secondary crude distillation column is connected to the feed inlet of the tertiary crude distillation column; the top outlet of the tertiary crude distillation column is connected to the feed inlet of the primary rectification column; the bottom outlet of the primary rectification column is connected to the feed inlet of the secondary rectification column; the bottom outlet of the secondary rectification column is connected to the feed inlet of the tertiary crude distillation column; the top outlet of the primary reduction column is connected to the fourth reboiler; and the top outlet of the secondary rectification column is connected to the third reboiler before proceeding to the reduction process.

[0016] In the distillation system described above, the pressure of the crude fractionation column is 0.40 MPaG to 0.47 MPaG, the column temperature is 87℃ to 122℃, the reflux ratio is 3.2 to 4.2, and the column diameter is 3700 mm to 4300 mm.

[0017] In the distillation system described above, the pressure of the crude distillation first-stage column is 0.23 MPaG to 0.25 MPaG, the column temperature is 58℃ to 72℃, the reflux ratio is 13 to 23, and the column diameter is 3300 mm to 3900 mm.

[0018] In the distillation system described above, the pressure of the crude distillation secondary column is 0.15 MPaG to 0.19 MPaG, the column temperature is 61℃ to 65℃, the reflux ratio is 2.5 to 3.5, and the column diameter is 6000 mm to 6600 mm.

[0019] In the distillation system described above, the crude distillation three-stage column has a column pressure of 0.15 MPaG to 0.18 MPaG, a column temperature of 61℃ to 65℃, a reflux ratio of 2.3 to 3.3, and a column diameter of 5400 mm to 6000 mm.

[0020] In the distillation system described above, the pressure of the first-stage distillation column is 0.40 MPaG to 0.41 MPaG, the column temperature is 87℃ to 88℃, the reflux ratio is 30 to 50, and the column diameter is 3100 mm to 3700 mm.

[0021] In the distillation system described above, the pressure of the secondary distillation column is 0.28 MPaG to 0.30 MPaG, the column temperature is 76℃ to 78℃, the reflux ratio is 2.7 to 3.7, and the column diameter is 4900 mm to 5500 mm.

[0022] In the distillation system described above, the pressure of the first-stage reduction column is 0.50 MPaG to 0.52 MPaG, the temperature is 93℃ to 127℃, the reflux ratio is 2.0 to 3.0, and the diameter is 5700 mm to 6800 mm.

[0023] Secondly, the present invention provides a distillation method using trichlorosilane multi-tower differential pressure coupling, which is carried out using the distillation system described above.

[0024] The trichlorosilane multi-tower differential pressure coupled distillation system provided by this invention, through the coupling of the crude distillation tower and the crude distillation secondary tower, and the separate coupling of the light-light removal tower, the crude distillation primary tower and the rectification primary tower, can reduce the reflux ratio of the light-light removal tower, effectively save energy consumption in the trichlorosilane distillation process, and reduce equipment investment and operating costs. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a trichlorosilane distillation system in the prior art;

[0027] Figure 2 This is a schematic diagram of a trichlorosilane multi-tower differential pressure coupling distillation system provided by the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1-Crude distillation column; 2-First-stage crude distillation column; 3-Second-stage crude distillation column; 4-Third-stage crude distillation column; 5-First-stage rectification column; 6-Second-stage rectification column; 7-First-stage reduction column; 8-First reboiler; 9-Second reboiler; 10-Third reboiler; 11-Fourth reboiler. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] In a first aspect, the present invention provides a trichlorosilane multi-tower differential pressure coupled distillation system, such as... Figure 2 As shown, it includes a crude distillation column 1, a light distillation removal column, and a heavy distillation removal column; the light distillation removal column includes a primary crude distillation column 2 and a primary rectification column 5, and the heavy distillation removal column includes a secondary crude distillation column 3; the primary crude distillation column 2 has a first reboiler 8, and the secondary crude distillation column 3 has a second reboiler 9; the top outlet of the crude distillation column 1 is connected to the second reboiler 9, and then connected to the feed inlet of the primary crude distillation column 2, and the top outlet of the primary rectification column 5 is connected to the first reboiler 8.

[0032] The materials to be separated in this invention come from the condensation system and mainly include trichlorosilane, silicon tetrachloride, dichlorosilane and other impurity components.

[0033] The distillation system of this invention specifically includes: the material to be separated enters the crude distillation column 1 from the feed inlet for crude distillation column 1 for crude separation; silicon tetrachloride is collected from the lower side of the crude distillation column 1 and returned to the cold hydrogenation reactor; high-boiling-point substances are ejected from the bottom of the column, i.e., heavy components are separated, yielding a first intermediate material (mainly including trichlorosilane and dichlorosilane). The first intermediate material is output from the top outlet of the crude distillation column 1 and enters the second reboiler 9 of the crude distillation secondary column 3 to provide heat for the crude distillation secondary column 3, forming a liquid phase. A portion of the liquid phase enters the crude distillation primary column 2 through the feed inlet for first crude distillation treatment, so that the light components (mainly including dichlorosilane) in the first intermediate material are collected from the top of the crude distillation primary column 2, yielding a second intermediate material (mainly including trichlorosilane and heavy components). The crude distillation secondary column 3 can fully utilize the heat of the gas phase at the top of the crude distillation column 1, reducing the total steam consumption.

[0034] Meanwhile, the light components (mainly boron and phosphorus compounds with boiling points between dichlorosilane and trichlorosilane) in the fourth intermediate material of the first-stage distillation column 5 are discharged through the top outlet of the first-stage distillation column 5 and enter the first reboiler 8 of the first-stage crude distillation column 2. This provides heat to the first-stage crude distillation column 2 and discharges the light components (mainly dichlorosilane), thus reducing the reflux ratio of the first-stage crude distillation column 2 and the first-stage distillation column 5. The heat of the first-stage distillation column 5 is provided by steam. The first-stage crude distillation column 2 can fully utilize the vapor phase heat at the top of the first-stage distillation column 5, reducing the total steam consumption.

[0035] The trichlorosilane multi-tower differential pressure coupled distillation system provided by the present invention, through the coupling of the crude distillation tower 1 and the crude distillation secondary tower 3, and the separate coupling of the light-light removal tower crude distillation primary tower 2 and the rectification primary tower 5, can reduce the reflux ratio of the light-light removal tower, effectively save energy consumption in the trichlorosilane distillation process, and reduce equipment investment and operating costs.

[0036] In some embodiments of the present invention, the deweighting tower further includes a crude distillation three-stage tower 4 and a rectification two-stage tower 6, and the rectification system further includes a reduction first-stage tower 7; the crude distillation three-stage tower 4 has a third reboiler 10, and the rectification two-stage tower 6 has a fourth reboiler 11; the bottom outlet of the crude distillation first-stage tower 2 is connected to the feed inlet of the crude distillation second-stage tower 3, the top outlet of the crude distillation second-stage tower 3 is connected to the feed inlet of the crude distillation three-stage tower 4, the top outlet of the crude distillation three-stage tower 4 is connected to the feed inlet of the rectification first-stage tower 5, the bottom outlet of the rectification first-stage tower 5 is connected to the feed inlet of the rectification second-stage tower 6, the bottom outlet of the rectification second-stage tower 6 is connected to the feed inlet of the crude distillation three-stage tower 4, the top outlet of the reduction first-stage tower 7 is connected to the fourth reboiler 11, and the top outlet of the rectification second-stage tower 6 is connected to the third reboiler 10 before proceeding to the reduction process.

[0037] In this invention, the second intermediate material (mainly including trichlorosilane and heavy components) is collected from the bottom of the first crude distillation column 2 and enters the second crude distillation column 3 through the raw material inlet for second crude distillation treatment, so that the heavy components in the second intermediate material with boiling points higher than trichlorosilane are collected from the bottom of the second crude distillation column 3 to obtain the third intermediate material (mainly including trichlorosilane).

[0038] The third intermediate material is collected from the top of the second-stage crude distillation column 3 and enters the third-stage crude distillation column 4 through the feed inlet for third-stage crude distillation. This further separates the heavy components with boiling points higher than trichlorosilane from the third intermediate material. These heavy components are then collected from the bottom of the third-stage crude distillation column 4. The remaining fourth intermediate material, mainly containing trichlorosilane, is collected from the top of the third-stage crude distillation column 4 and enters the first-stage rectification column 5 through the feed inlet for first-stage rectification. In the first-stage distillation column 5, the light components of the fourth intermediate material (mainly boron and phosphorus compounds with boiling points between dichlorosilane and trichlorosilane) are collected from the top of the first-stage distillation column 5, and the remaining fifth intermediate material, mainly containing trichlorosilane, is collected from the bottom of the first-stage distillation column 5. The fifth intermediate material is then fed into the second-stage distillation column 6 through the feed inlet for a second distillation process. In the second-stage distillation column 6, the heavy components of the fifth intermediate material are further separated to obtain high-purity trichlorosilane. In the reduction process, after the first-stage reduction column 7 provides heat to the fourth reboiler 11 of the second-stage distillation column 6, part of it is refluxed, and the other part enters the third-stage crude distillation column 4 through the feed inlet for further separation to further extract trichlorosilane from the fifth intermediate material. The high-purity trichlorosilane obtained from the second-stage distillation column 6 is collected from the top of the second-stage distillation column 6 and enters the third reboiler 10 of the third-stage crude distillation column 4 to provide heat to the third-stage crude distillation column 4. The high-purity trichlorosilane that has used up the heat is then sent to the reduction process.

[0039] This invention optimizes the coupling relationship between the primary crude distillation column 2, the secondary crude distillation column 3, the tertiary crude distillation column 4, the primary rectification column 5, the secondary rectification column 6, and the primary reduction column 7. This reduces the reflux ratio of the primary crude distillation column 2 and the primary rectification column 5, effectively saving energy consumption in the trichlorosilane distillation process, reducing equipment investment and operating costs, and has broad application prospects.

[0040] The distillation system of the present invention can reduce the reflux ratio, column diameter, steam consumption, reflux tank volume and reflux pump flow rate of the crude distillation first-stage column 2 and the rectification first-stage column 5; and reduce the column pressure of the crude distillation second-stage column 3 and the crude distillation third-stage column 4. High-purity trichlorosilane can be obtained while saving energy consumption, equipment investment and operating costs.

[0041] In this invention, an example of an annual polysilicon production capacity of 5wt is used for illustrative purposes.

[0042] In some embodiments of the present invention, the pressure of the coarse separation tower 1 is 0.40 MPaG to 0.47 MPaG, for example, it can be a range of 0.40 MPaG, 0.41 MPaG, 0.42 MPaG, 0.43 MPaG, 0.44 MPaG, 0.45 MPaG, 0.46 MPaG, 0.47 MPaG, or any combination thereof; the tower temperature is 87°C to 122°C, for example, it can be 87°C, 90°C, 92°C, 95°C, or 100°C. The temperature range is 110℃, 120℃, 122℃ or any two of these; the reflux ratio is 3.2 to 4.2, for example, it can be 3.2, 3.4, 3.6, 3.8, 4.0, 4.2 or any two of these; the tower diameter is 3700mm to 4300mm, for example, it can be 3700mm, 3800mm, 3900mm, 4000mm, 4100mm, 4200mm, 4300mm or any two of these.

[0043] Figure 1 In the distillation system shown, the pressure of the crude distillation column 1 is 0.15 MPaG to 0.22 MPaG, the temperature is 60℃ to 97℃, the reflux ratio is 3.7, and the diameter is 4600 mm. It can be seen that the distillation system of the present invention can reduce the diameter of the crude distillation column 1, and the higher pressure and temperature of the crude distillation column 1 can provide heat for the secondary crude distillation column 3, reducing steam consumption.

[0044] In some embodiments of the present invention, the pressure of the crude distillation primary column 2 is 0.23 MPaG to 0.25 MPaG, for example, it can be a range of 0.23 MPaG, 0.235 MPaG, 0.24 MPaG, 0.245 MPaG, 0.25 MPaG, or any two of these; the column temperature is 58°C to 72°C, for example, it can be a range of 58°C, 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, or any two of these; the reflux ratio is 13 to 23, for example, it can be a range of 13, 15, 17, 19, 20, 23, or any two of these; the column diameter is 3300 mm to 3900 mm, for example, it can be a range of 3300 mm, 3400 mm, 3500 mm, 3600 mm, 3700 mm, 3800 mm, 3900 mm, or any two of these.

[0045] Figure 1In the distillation system shown, the pressure of the crude distillation column 2 is 0.23 MPaG to 0.25 MPaG, the column temperature is 58℃ to 72℃, the reflux ratio is 66.4, and the column diameter is 6400 mm. It can be seen that the distillation system of the present invention can reduce the reflux ratio and column diameter of the crude distillation column 2, effectively saving energy consumption in the trichlorosilane distillation process.

[0046] In some embodiments of the present invention, the pressure of the crude distillation secondary column 3 is 0.15 MPaG to 0.19 MPaG, for example, it can be a range of 0.15 MPaG, 0.16 MPaG, 0.17 MPaG, 0.18 MPaG, 0.19 MPaG, or any two of these; the column temperature is 61℃ to 65℃, for example, it can be a range of 61℃, 62℃, 63℃, 64℃, 65℃, or any two of these; the reflux ratio is 2.5 to 3.5, for example, it can be a range of 2.5, 2.7, 2.9, 3.0, 3.3, 3.5, or any two of these; the column diameter is 6000 mm to 6600 mm, for example, it can be a range of 6000 mm, 6100 mm, 6200 mm, 6300 mm, 6400 mm, 6500 mm, 6600 mm, or any two of these.

[0047] Figure 1 In the distillation system shown, the pressure of the crude distillation stage 3 is 0.75 MPaG to 0.79 MPaG, the temperature is 111℃ to 113℃, the reflux ratio is 4.1, and the diameter is 6700 mm. It can be seen that the distillation system of this invention can reduce the pressure, temperature, reflux ratio, and diameter of the crude distillation stage 3, which is beneficial for the removal of heavy components in the crude distillation stage 3, effectively saving energy consumption in the trichlorosilane distillation process, and reducing equipment investment and operating costs.

[0048] In some embodiments of the present invention, the pressure of the crude distillation three-stage column 4 is 0.15 MPaG to 0.18 MPaG, for example, it can be a range of 0.15 MPaG, 0.16 MPaG, 0.165 MPaG, 0.17 MPaG, 0.18 MPaG, or any two of these; the column temperature is 61℃ to 65℃, for example, it can be a range of 61℃, 62℃, 63℃, 64℃, 65℃, or any two of these; the reflux ratio is 2.3 to 3.3, for example, it can be a range of 2.3, 2.5, 2.8, 3.0, 3.1, 3.3, or any two of these; the column diameter is 5400 mm to 6000 mm, for example, it can be a range of 5400 mm, 5500 mm, 5600 mm, 5700 mm, 5800 mm, 5900 mm, 6000 mm, or any two of these.

[0049] Figure 1In the distillation system shown, the pressure of the crude distillation three-stage column 4 is 0.41 MPaG to 0.44 MPaG, the temperature is 88℃ to 90℃, the reflux ratio is 3.8, and the column diameter is 6100 mm. It can be seen that the distillation system of the present invention can reduce the pressure, temperature, reflux ratio, and diameter of the crude distillation three-stage column 4, effectively saving energy consumption in the trichlorosilane distillation process and reducing equipment investment and operating costs.

[0050] In this invention, using a crude distillation three-stage column 4 as the last stage of the coupling can reduce the column pressure, column temperature, reflux ratio and column diameter of the crude distillation three-stage column 4, which is beneficial to the removal of heavy components in the crude distillation three-stage column 4.

[0051] In some embodiments of the present invention, the pressure of the first-stage distillation column 5 is 0.40 MPaG to 0.41 MPaG, for example, it can be a range of 0.40 MPaG, 0.402 MPaG, 0.404 MPaG, 0.406 MPaG, 0.408 MPaG, 0.41 MPaG, or any combination thereof; the column temperature is 87°C to 88°C, for example, it can be 87°C, 87.2°C, 87.4°C, 87.6°C, or 87°C. The temperature range is 8℃, 88℃, or any two of these; the reflux ratio is 30 to 50, for example, it can be 30, 32, 35, 38, 40, 42, 45, 48, 50, or any two of these; the tower diameter is 3100mm to 3700mm, for example, it can be 3100mm, 3200mm, 3300mm, 3400mm, 3500mm, 3600mm, 3700mm, or any two of these.

[0052] Figure 1 In the distillation system shown, the pressure of the first-stage distillation column 5 is 0.15 MPaG to 0.16 MPaG, the temperature is 61℃ to 62℃, the reflux ratio is 123.1, and the column diameter is 5700 mm. It can be seen that the distillation system of the present invention can reduce the reflux ratio and column diameter of the first-stage distillation column 5, effectively saving energy consumption in the trichlorosilane distillation process. Furthermore, the higher pressure and temperature of the first-stage distillation column 5 of the present invention can provide heat for the crude distillation column 2, reducing steam consumption.

[0053] In some embodiments of the present invention, the pressure of the secondary distillation column 6 is 0.28 MPaG to 0.30 MPaG, for example, it can be a range of 0.28 MPaG, 0.285 MPaG, 0.29 MPaG, 0.295 MPaG, 0.30 MPaG, or any two of these; the column temperature is 76°C to 78°C, for example, it can be a range of 76°C, 76.5°C, 77°C, 77.5°C, 78°C, or any two of these; the reflux ratio is 2.7 to 3.7, for example, it can be a range of 2.7, 3.0, 3.2, 3.5, 3.6, 3.7, or any two of these; the column diameter is 4900 mm to 5500 mm, for example, it can be a range of 4900 mm, 5000 mm, 5100 mm, 5200 mm, 5300 mm, 5400 mm, 5500 mm, or any two of these.

[0054] Figure 1 In the distillation system shown, the pressure of the secondary distillation column 6 is 0.28 MPaG to 0.30 MPaG, the temperature is 76℃ to 78℃, the reflux ratio is 3.2, and the column diameter is 5500 mm. It can be seen that in the distillation system of this invention, the secondary distillation column 6 and... Figure 1 The pressure, temperature, reflux ratio, and diameter of the secondary distillation column 6 are basically the same.

[0055] In some embodiments of the present invention, the pressure of the reduction primary column 7 is 0.50 MPaG to 0.52 MPaG, for example, it can be a range of 0.50 MPaG, 0.505 MPaG, 0.51 MPaG, 0.515 MPaG, 0.52 MPaG, or any combination thereof; the column temperature is 93℃ to 127℃, for example, it can be 93℃, 95℃, 98℃, 100℃, 110℃, 120℃, 125℃, etc. The temperature range is 127℃ or any combination thereof; the reflux ratio is 2.0 to 3.0, for example, it can be 2.0, 2.2, 2.4, 2.5, 2.7, 3.0 or any combination thereof; the tower diameter is 5700mm to 6800mm, for example, it can be 5700mm, 5900mm, 6000mm, 6100mm, 6300mm, 6500mm, 6800mm or any combination thereof.

[0056] Figure 1 In the distillation system shown, the pressure of the first-stage reduction column 7 is 0.50 MPaG to 0.52 MPaG, the temperature is 93℃ to 127℃, the reflux ratio is 2.5, and the column diameter is 5700 to 6800 mm. It can be seen that the first-stage reduction column 7 in the distillation system of this invention... Figure 1The pressure, temperature, reflux ratio and diameter of the first-stage reduction column 7 are basically the same, which can provide heat for the second-stage distillation column 6 and the third-stage crude distillation column 4, reducing steam consumption.

[0057] This invention can improve the separation efficiency of crude distillation column 1, crude distillation primary column 2, crude distillation secondary column 3, crude distillation tertiary column 4, rectification primary column 5, and rectification secondary column 6 while saving energy, thus obtaining high-purity trichlorosilane. In particular, by making crude distillation tertiary column 4 the last coupled column, the column pressure, column temperature, reflux ratio, and column diameter of crude distillation tertiary column 4 can be reduced, which is beneficial to the removal of heavy components in crude distillation tertiary column 4; at the same time, the column pressure, column temperature, reflux ratio, and column diameter of crude distillation secondary column 3 can also be reduced, which is beneficial to the removal of heavy components in crude distillation secondary column 3.

[0058] It is understood that the tower pressure in this invention is the total tower pressure. In each tower, the pressure at the bottom of the tower is greater than the pressure at the top of the tower, and the pressure of the next stage tower coupled with the tower is less than the pressure of the previous stage tower coupled with the tower.

[0059] The tower temperature in this invention refers to the temperature of the entire tower.

[0060] like Figure 2 As shown, compared to Figure 1 The existing distillation system shown is different from the distillation system of the present invention. In the distillation system of the present invention, the crude separation column 1 is coupled to the crude distillation secondary column 3, the primary distillation column 5 is coupled to the crude distillation primary column 2, the reduction primary column 7 is coupled to the secondary distillation column 6, and the secondary distillation column 6 is coupled to the crude distillation tertiary column 4 (the crude separation column 1 provides heat to the crude distillation secondary column 3, the primary distillation column 5 provides heat to the crude distillation primary column 2, the reduction primary column 7 provides heat to the secondary distillation column 6, and the secondary distillation column 6 provides heat to the crude distillation tertiary column 4). The distillation system of the present invention reduces the column pressure and column temperature of the crude distillation secondary column 3 and the crude distillation tertiary column 4, reduces the reflux ratio of the crude distillation primary column 2, the crude distillation secondary column 3, the crude distillation tertiary column 4, and the primary distillation column 5, and reduces the column diameter of the crude separation column 1, the crude distillation primary column 2, the crude distillation secondary column 3, the crude distillation tertiary column 4, and the primary distillation column 5, which not only improves the separation efficiency but also effectively reduces equipment investment and operating costs.

[0061] Furthermore, Figure 1 The total steam consumption at 0.4 MPa in the distillation system shown is 194.5 t / h; Figure 2 The total steam consumption at 0.4 MPa in the distillation system of the present invention is 144.4 t / h. It can be concluded that, compared to... Figure 1 Compared with the existing distillation system, the distillation system of the present invention reduces the total steam consumption, demonstrating that the distillation system of the present invention can effectively save energy consumption in the distillation process of trichlorosilane.

[0062] Secondly, the present invention provides a distillation method using a trichlorosilane multi-tower differential pressure coupling system, which is carried out using the distillation system described above.

[0063] The trichlorosilane multi-tower differential pressure coupling distillation method of the present invention uses the distillation system described above. This method can reduce the reflux ratio of the light distillation tower, namely the crude distillation first-stage tower 2 and the rectification first-stage tower 5, and has the advantage of low energy consumption, making it suitable for widespread application.

[0064] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0065] Example 1

[0066] The trichlorosilane multi-tower differential pressure coupled distillation system in this embodiment is as follows: Figure 2 As shown, it includes:

[0067] The distillation tower consists of: 1. Crude distillation first-stage tower; 2. Crude distillation second-stage tower; 3. Crude distillation third-stage tower; 4. Rectification first-stage tower; 5. Rectification second-stage tower; 6. Reduction first-stage tower; and 7.

[0068] The primary crude distillation column 2 has a first reboiler 8, the secondary crude distillation column 3 has a second reboiler 9, the tertiary crude distillation column 4 has a third reboiler 10, and the secondary rectification column 6 has a fourth reboiler 11.

[0069] After the top outlet of the crude distillation column 1 is connected to the second reboiler 9, it is then connected to the feed inlet of the crude distillation first-stage column 2, and the top outlet of the rectification first-stage column 5 is connected to the first reboiler 8.

[0070] The bottom outlet of the first-stage crude distillation column 2 is connected to the feed inlet of the second-stage crude distillation column 3. The top outlet of the second-stage crude distillation column 3 is connected to the feed inlet of the third-stage crude distillation column 4. The top outlet of the third-stage crude distillation column 4 is connected to the feed inlet of the first-stage rectification column 5. The bottom outlet of the first-stage rectification column 5 is connected to the feed inlet of the second-stage rectification column 6. The bottom outlet of the second-stage rectification column 6 is connected to the feed inlet of the third-stage crude distillation column 4. The top outlet of the first-stage reduction column 7 is connected to the fourth reboiler 11. The top outlet of the second-stage rectification column 6 is connected to the third reboiler 10 before proceeding to the reduction process.

[0071] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A trichlorosilane multi-tower differential pressure coupled distillation system, characterized in that, It includes a crude distillation column, a light distillation column, and a heavy distillation column; the light distillation column includes a primary crude distillation column and a primary rectification column, and the heavy distillation column includes a secondary crude distillation column. The primary crude distillation column has a first reboiler, and the secondary crude distillation column has a second reboiler; The top outlet of the crude distillation column is connected to the second reboiler, and then to the feed inlet of the primary crude distillation column. The top outlet of the primary rectification column is connected to the first reboiler.

2. The distillation system according to claim 1, characterized in that, The deweight removal tower also includes a three-stage crude distillation tower and a two-stage rectification tower, and the rectification system also includes a first-stage reduction tower; The crude distillation three-stage column has a third reboiler, and the rectification two-stage column has a fourth reboiler; The bottom outlet of the primary crude distillation column is connected to the feed inlet of the secondary crude distillation column; the top outlet of the secondary crude distillation column is connected to the feed inlet of the tertiary crude distillation column; the top outlet of the tertiary crude distillation column is connected to the feed inlet of the primary rectification column; the bottom outlet of the primary rectification column is connected to the feed inlet of the secondary rectification column; the bottom outlet of the secondary rectification column is connected to the feed inlet of the tertiary crude distillation column; the top outlet of the primary reduction column is connected to the fourth reboiler; and the top outlet of the secondary rectification column is connected to the third reboiler before proceeding to the reduction process.

3. The distillation system according to claim 1 or 2, characterized in that, The coarse separator has a pressure of 0.40 MPaG to 0.47 MPaG, a temperature of 87℃ to 122℃, a reflux ratio of 3.2 to 4.2, and a diameter of 3700 mm to 4300 mm.

4. The distillation system according to claim 1, characterized in that, The crude distillation primary column has a pressure of 0.23 MPaG to 0.25 MPaG, a temperature of 58℃ to 72℃, a reflux ratio of 13 to 23, and a diameter of 3300 mm to 3900 mm.

5. The distillation system according to claim 1, characterized in that, The crude distillation secondary column has a column pressure of 0.15 MPaG to 0.19 MPaG, a column temperature of 61℃ to 65℃, a reflux ratio of 2.5 to 3.5, and a column diameter of 6000 mm to 6600 mm.

6. The distillation system according to claim 2, characterized in that, The crude distillation three-stage column has a column pressure of 0.15 MPaG to 0.18 MPaG, a column temperature of 61℃ to 65℃, a reflux ratio of 2.3 to 3.3, and a column diameter of 5400 mm to 6000 mm.

7. The distillation system according to claim 1, characterized in that, The first-stage distillation column has a pressure of 0.40 MPaG to 0.41 MPaG, a temperature of 87℃ to 88℃, a reflux ratio of 30 to 50, and a diameter of 3100 mm to 3700 mm.

8. The distillation system according to claim 2 or 6, characterized in that, The distillation column has a pressure of 0.28 MPaG to 0.30 MPaG, a temperature of 76℃ to 78℃, a reflux ratio of 2.7 to 3.7, and a diameter of 4900 mm to 5500 mm.

9. The distillation system according to claim 2, characterized in that, The reduction first-stage column has a column pressure of 0.50 MPaG to 0.52 MPaG, a column temperature of 93℃ to 127℃, a reflux ratio of 2.0 to 3.0, and a column diameter of 5700 mm to 6800 mm.

10. A distillation method using trichlorosilane multi-tower differential pressure coupling, characterized in that, The distillation system described in any one of claims 1-9 shall be used.

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