Trichlorosilane multi-tower differential pressure coupling rectification system and rectification method

Abstract

The invention provides a trichlorosilane multi-tower differential pressure coupling rectification system and rectification method. The trichlorosilane multi-tower differential pressure coupling rectification system comprises a coarse separation tower and a light component removal tower, the light component removal tower is provided with a reboiler, and the tower top outlet of the coarse separation tower is communicated with the reboiler of the light component removal tower and then is communicated with the raw material inlet of the light component removal tower. According to the trichlorosilane multi-tower differential pressure coupling rectification system provided by the invention, the reflux ratio of the light component removal tower can be reduced, the energy consumption in the trichlorosilane rectification process is effectively saved, and the equipment investment and operation cost are reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of rectification, and particularly relates to a multi-tower differential pressure coupled rectification system and method for trichlorosilane. BACKGROUND

[0002] In the production of high-purity polysilicon, the Siemens method has been widely used as a traditional process. However, with the rapid development of the solar photovoltaic industry, the demand for high-purity polysilicon has been increasing, and the cost and efficiency problems of the traditional Siemens method have gradually emerged. Therefore, the improved Siemens method has emerged as one of the key technologies to improve production efficiency and resource utilization.

[0003] The core of the improved Siemens method lies in the comprehensive utilization of silicon tetrachloride, a byproduct produced in the traditional Siemens process. How to effectively recover and convert silicon tetrachloride has become an important link to improve the economic efficiency of the process. Cold hydrogenation technology converts silicon tetrachloride into trichlorosilane by using a catalyst to promote the reaction of silicon powder, hydrogen, and silicon tetrachloride at high temperatures. This process not only improves the utilization efficiency of silicon tetrachloride but also reduces waste emissions.

[0004] In the cold hydrogenation process, the formation of synthesis gas is accompanied by some side reactions, generating dichlorosilane and other heavy components (such as methyl dichlorosilane). Therefore, how to effectively separate and purify trichlorosilane in the synthesis gas becomes a key process. Through multi-stage separation of cyclone separators, quench towers, and condensing systems, a synthesis liquid containing silicon tetrachloride, trichlorosilane, dichlorosilane, and other heavy components is obtained, which needs to be further separated to obtain high-purity trichlorosilane.

[0005] Figure 1 A schematic diagram of the existing technology for the rectification system of trichlorosilane is shown in FIG. 1. 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.

[0006] In the prior art rectification system, the crude distillation secondary tower 3 provides heat for the crude distillation tertiary tower 4, the crude distillation tertiary tower 4 provides heat for the crude distillation primary tower 2, the reduction primary tower 7 provides heat for the rectification secondary tower 6, and the rectification secondary tower 6 provides heat for the rectification primary tower 5. However, the reflux ratio of the crude distillation secondary tower 3, the crude distillation tertiary tower 4 and the rectification secondary tower 6 is 3-5, and the gas phase flow rate of the top of the crude distillation secondary tower 3, the crude distillation tertiary tower 4 and the rectification secondary tower 6 is large, and the material amount of the top of the crude distillation primary tower 2 is small. In order to enable the crude distillation primary tower 2 to utilize the heat of the crude distillation secondary tower 3 and the crude distillation tertiary tower 4, and enable the rectification primary tower 5 to utilize the heat of the rectification secondary tower 6, the reflux ratio of the crude distillation primary tower 2 and the rectification primary tower 5 is usually increased to 50-150, which is much larger than the actual reflux ratio required by the crude distillation primary tower 2 and the rectification primary tower 5, thereby increasing the equipment investment and operation cost of the crude distillation primary tower 2 and the rectification primary tower 5. SUMMARY

[0007] The main purpose of the present application is to provide a trichlorosilane multi-tower differential pressure coupled rectification system, which 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.

[0008] The present application also provides a trichlorosilane multi-tower differential pressure coupled rectification method, which uses the above-mentioned rectification system, so that the method can reduce the reflux ratio of the light removal tower and reduce the energy consumption.

[0009] In the first aspect, the present application provides a trichlorosilane multi-tower differential pressure coupled rectification system, which comprises a crude tower and a light removal tower.

[0010] The light removal tower has a reboiler, the top outlet of the crude tower is communicated with the reboiler of the light removal tower, and then communicated with the raw material inlet of the light removal tower.

[0011] The rectification system as described above, the light removal tower comprises a crude distillation primary tower and a rectification primary tower, the crude distillation primary tower has a first reboiler, the rectification primary tower has a fourth reboiler, the top outlet of the crude tower is communicated with the fourth reboiler, and then communicated with the raw material inlet of the crude distillation primary tower, and the top outlet of the rectification primary tower is communicated with the first reboiler.

[0012] The rectification system as described above, the light removal tower comprises a crude distillation primary tower and a rectification primary tower, the crude distillation primary tower has a first reboiler, the rectification primary tower has a fourth reboiler, the top outlet of the crude tower is communicated with the first reboiler and the fourth reboiler respectively, and then communicated with the raw material inlet of the crude distillation primary tower.

[0013] The rectification system as described above, further comprising a heavy-removing column and a reducing primary column, the heavy-removing column comprising a crude distillation secondary column, a crude distillation tertiary column and a rectification secondary column; the crude distillation secondary column having a second reboiler, the crude distillation tertiary column having a third reboiler, and the rectification secondary column having a fifth reboiler;

[0014] The column bottom outlet of the crude distillation primary column is communicated with the raw material inlet of the crude distillation secondary column, the column top outlet of the crude distillation secondary column is communicated with the raw material inlet of the crude distillation tertiary column, the column top outlet of the crude distillation tertiary column is communicated with the second reboiler and then with the raw material inlet of the rectification primary column, the column bottom outlet of the rectification primary column is communicated with the raw material inlet of the rectification secondary column, the column bottom outlet of the rectification secondary column is communicated with the raw material inlet of the crude distillation tertiary column, the column top outlet of the reducing primary column is communicated with the fifth reboiler, and the column top outlet of the rectification secondary column is communicated with the third reboiler and then goes to the reducing process.

[0015] The rectification system as described above, the tower pressure of the crude fractionation column is 0.65MPaG-0.72MPaG, the tower temperature is 106℃-140℃, the reflux ratio is 3.2-4.2, and the tower diameter is 3700mm-4400mm;

[0016] And / or, the tower pressure of the crude distillation primary column is 0.23MPaG-0.25MPaG, the tower temperature is 58℃-72℃, the reflux ratio is 48-68, and the tower diameter is 5500mm-6200mm;

[0017] And / or, the tower pressure of the rectification primary column is 0.40MPaG-0.41MPaG, the tower temperature is 87℃-88℃, the reflux ratio is 105-120, and the tower diameter is 4800mm-5500mm.

[0018] The rectification system as described above, the tower pressure of the crude fractionation column is 0.45MPaG-0.52MPaG, the tower temperature is 91℃-126℃, the reflux ratio is 3.2-4.2, and the tower diameter is 3900mm-4400mm;

[0019] And / or, the tower pressure of the crude distillation primary column is 0.23MPaG-0.25MPaG, the tower temperature is 58℃-72℃, the reflux ratio is 25-35, and the tower diameter is 4000mm-5000mm;

[0020] And / or, the tower pressure of the rectification primary column is 0.15MPaG-0.16MPaG, the tower temperature is 61℃-62℃, the reflux ratio is 55-75, and the tower diameter is 3700mm-4700mm.

[0021] The rectification system as described above, wherein the crude distillation secondary tower has a tower pressure of 0.15-0.19 MPaG, a tower temperature of 61-65℃, a reflux ratio of 2.2-3.2, and a tower diameter of 6000-6500 mm.

[0022] The rectification system as described above, wherein the crude distillation tertiary tower has a tower pressure of 0.32-0.35 MPaG, a tower temperature of 80-83℃, a reflux ratio of 2.3-3.3, and a tower diameter of 5100-6000 mm.

[0023] The rectification system as described above, wherein the rectification secondary tower has a tower pressure of 0.55-0.57 MPaG, a tower temperature of 98-100℃, a reflux ratio of 2.9-3.9, and a tower diameter of 4800-5300 mm.

[0024] And / or, the reduction primary tower has a tower pressure of 0.85-0.87 MPaG, a tower temperature of 114-149℃, a reflux ratio of 2.0-3.0, and a tower diameter of 5700-6800 mm.

[0025] In a second aspect, the present application provides a method for rectifying trichlorosilane by using a multi-tower differential pressure coupled rectification system as described above.

[0026] The multi-tower differential pressure coupled rectification system for trichlorosilane provided by the present application can reduce the reflux ratio of the light-removing tower by optimizing the coupling relationship between the crude distillation tower and the light-removing tower, effectively saving the energy consumption in the rectification process of trichlorosilane, and reducing the equipment investment and operating cost. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the description of the embodiments of the present application or the related art are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0028] Figure 1 A schematic diagram of a rectification system for trichlorosilane in the prior art;

[0029] Figure 2 A schematic diagram of a multi-tower differential pressure coupled rectification system for trichlorosilane provided by the present application;

[0030] Figure 3 A schematic diagram of another multi-tower differential pressure coupled rectification system for trichlorosilane provided by the present application.

[0031] Explanation of reference signs:

[0032] 1 - crude column; 2 - first rectification column; 3 - second rectification column; 4 - third rectification column; 5 - first rectification column; 6 - second rectification column; 7 - first reduction column; 8 - first reboiler; 9 - second reboiler; 10 - third reboiler; 11 - fourth reboiler; 12 - fifth reboiler. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present application clearer, the following will describe the technical solutions in the embodiments of the present application in a clear and complete manner with reference to the embodiments of the present application. Obviously, the described embodiments are only some, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0034] In a first aspect, the present application provides a multi-column differential pressure coupled rectification system for trichlorosilane, as shown in Figure 2 or Figure 3 The rectification system comprises a crude column 1 and a light-removing column. The light-removing column has a reboiler. The overhead outlet of the crude column 1 is communicated with the reboiler of the light-removing column, and then communicated with the raw material inlet of the light-removing column.

[0035] The material to be separated in the present application comes from a condensation system, and mainly comprises trichlorosilane, silicon tetrachloride, dichlorosilane, and other impurities.

[0036] The rectification system of the present application specifically comprises: the material to be separated enters the crude column 1 from the raw material inlet of the crude column 1 for crude separation treatment. The silicon tetrachloride is returned to a cold hydrogenation reactor from the lower side of the crude column 1, and the high-boiling substances are discharged from the column sump, i.e. the heavy components are separated, to obtain a first intermediate material (mainly comprising trichlorosilane and dichlorosilane). The first intermediate material is output from the overhead outlet of the crude column 1, enters the reboiler of the light-removing column to provide heat for the light-removing column, and then enters the light-removing column from the raw material inlet of the light-removing column for light-removing treatment (mainly removing dichlorosilane), which can reduce the reflux ratio of the light-removing column. The heat of the crude column 1 is provided by steam. The light-removing column can fully utilize the overhead gas phase heat of the crude column 1, and reduce the total steam consumption.

[0037] The multi-column differential pressure coupled rectification system for trichlorosilane provided by the present application can reduce the reflux ratio of the light-removing column by optimizing the coupling relationship between the crude column 1 and the light-removing column, effectively save the energy consumption in the trichlorosilane rectification process, and reduce the equipment investment and operating cost.

[0038] In some embodiments of the present application, as shown in Figure 2As shown, the light removal column includes a first-stage rough distillation column 2 having a first reboiler 8 and a first-stage rectification column 5 having a fourth reboiler 11, and the overhead outlet of the rough separation column 1 is communicated with the fourth reboiler 11 and then with the raw material inlet of the first-stage rough distillation column 2, and the overhead outlet of the first-stage rectification column 5 is communicated with the first reboiler 8.

[0039] In the present application, the first intermediate material is output from the overhead outlet of the rough separation column 1, enters the fourth reboiler 11 of the first-stage rectification column 5 to provide heat for the first-stage rectification column 5, forms a liquid phase, and a part of the liquid phase is output from the overhead outlet of the first-stage rectification column 5, enters the first reboiler 8 of the first-stage rough distillation column 2 to provide heat for the first-stage rough distillation column 2, and outputs the light component (mainly including dichlorodihydrogen silicon).

[0040] In the present application, the coupling relationship between the light removal column and the rough separation column 1 can further make full use of the heat of the gas phase at the overhead of the rough separation column 1, reduce the total steam consumption, reduce the reflux ratio of the light removal column, effectively save the energy consumption in the trichlorosilane rectification process, and reduce the equipment investment and operation cost.

[0041] In some embodiments of the present application, as shown in Figure 3 As shown, the light removal column includes a first-stage rough distillation column 2 having a first reboiler 8 and a first-stage rectification column 5 having a fourth reboiler 11, and the overhead outlet of the rough separation column 1 is communicated with the first reboiler 8 and the fourth reboiler 11 respectively and then with the raw material inlet of the first-stage rough distillation column 2.

[0042] In the present application, the first intermediate material is output from the overhead outlet of the rough separation column 1, enters the fourth reboiler 11 of the first-stage rectification column 5 to provide heat for the first-stage rectification column 5, forms a liquid phase, and a part of the liquid phase is output from the overhead outlet of the first-stage rectification column 5, enters the first reboiler 8 of the first-stage rough distillation column 2 to provide heat for the first-stage rough distillation column 2, and outputs the light component (mainly including dichlorodihydrogen silicon).

[0043] In the present application, the coupling relationship of the light removal column and the coarse separation column 1 can further make full use of the heat of the gas phase at the top of the coarse separation column 1, reduce the total steam consumption, reduce the reflux ratio of the light removal column, effectively save the energy consumption in the trichlorosilane rectification process, and reduce the equipment investment and operation cost.

[0044] In some embodiments of the present application, as shown in Figure 2 or Figure 3 The rectification system further comprises a heavy removal column and a reduction primary column 7, the heavy removal column comprises a coarse distillation secondary column 3, a coarse distillation tertiary column 4 and a rectification secondary column 6; the coarse distillation secondary column 3 is provided with a second reboiler 9, the coarse distillation tertiary column 4 is provided with a third reboiler 10, and the rectification secondary column 6 is provided with a fifth reboiler 12; the column kettle outlet of the coarse distillation primary column 2 is communicated with the raw material inlet of the coarse distillation secondary column 3, the top outlet of the coarse distillation secondary column 3 is communicated with the raw material inlet of the coarse distillation tertiary column 4, the top outlet of the coarse distillation tertiary column 4 is communicated with the second reboiler 9 and then with the raw material inlet of the rectification primary column 5, the column kettle outlet of the rectification primary column 5 is communicated with the raw material inlet of the rectification secondary column 6, the column kettle outlet of the rectification secondary column 6 is communicated with the raw material inlet of the coarse distillation tertiary column 4, the top outlet of the reduction primary column 7 is communicated with the fifth reboiler 12, and the top outlet of the rectification secondary column 6 is communicated with the third reboiler 10 and then goes to the reduction process.

[0045] In the present application, the second intermediate material (mainly including trichlorosilane and heavy components) is taken out from the bottom of the first crude distillation column 2, enters the second crude distillation column 3 through the raw material inlet of the second crude distillation column 3, and is subjected to the second crude distillation treatment, so that the heavy components with a boiling point higher than that of trichlorosilane in the second intermediate material are taken out from the bottom of the second crude distillation column 3, and the third intermediate material (mainly including trichlorosilane) is obtained; the third intermediate material is taken out from the top of the second crude distillation column 3, enters the third crude distillation column 4 through the raw material inlet of the third crude distillation column 4, and is subjected to the third crude distillation treatment, so that the heavy components with a boiling point higher than that of trichlorosilane in the third intermediate material are taken out from the bottom of the third crude distillation column 4, and the fourth intermediate material (mainly including trichlorosilane) remaining in the third intermediate material is taken out from the top of the third crude distillation column 4, enters the second reboiler 9 of the second crude distillation column 3 to provide heat for the second crude distillation column 3, forms a liquid phase, part of which is refluxed, and the other part enters the first rectification column 5 through the raw material inlet of the first rectification column 5 and is subjected to the first rectification treatment; in the first rectification column 5, the light components (mainly including boron and phosphorus compounds with a boiling point between dichlorosilane and trichlorosilane) in the fourth intermediate material are taken out from the top of the first rectification column 5, and the fifth intermediate material (mainly including trichlorosilane) remaining in the fourth intermediate material is taken out from the bottom of the first rectification column 5; the fifth intermediate material enters the second rectification column 6 through the raw material inlet of the second rectification column 6 and is subjected to the second rectification treatment; in the second rectification column 6, the heavy components in the fifth intermediate material are further separated, and high-purity trichlorosilane is obtained; the first reduction column 7 in the reduction process provides heat for the fifth reboiler 12 of the second rectification column 6, part of which is refluxed, and the other part enters the third crude distillation column 4 for further separation, so as to further extract trichlorosilane in the fifth intermediate material, and the high-purity trichlorosilane obtained by the second rectification column 6 is taken out from the top of the second rectification column 6, enters the third reboiler 10 of the third crude distillation column 4 to provide heat for the third crude distillation column 4, and the high-purity trichlorosilane after the heat is used to reduce the first reduction column 7.

[0046] By optimizing the coupling relationship among the first crude distillation column 2, the second crude distillation column 3, the third crude distillation column 4, the first rectification column 5, the second rectification column 6 and the first reduction column 7, the present application can reduce the reflux ratio of the first crude distillation column 2 and the first rectification column 5, effectively save the energy consumption in the trichlorosilane rectification process, reduce the equipment investment and operation cost, and has a wide application prospect.

[0047] The rectification system of the present application can reduce the reflux ratio, column diameter, steam consumption, volume of reflux tank and flow of reflux pump of the first crude distillation column 2 and the first rectification column 5, and can reduce the column pressure of the second crude distillation column 3 and the third crude distillation column 4, so as to obtain high-purity trichlorosilane under the conditions of saving energy consumption, equipment investment and operation cost.

[0048] In the present application, the annual production capacity of 5wt polysilicon is taken as an example for illustrative description.

[0049] In some embodiments of the present application, as shown in Figure 2 The tower pressure of the crude fractionating tower 1 is 0.65 MPaG-0.72 MPaG, for example, can be 0.65 MPaG, 0.67 MPaG, 0.69 MPaG, 0.70 MPaG, 0.72 MPaG or a range consisting of any two of them; the tower temperature is 106℃-140℃, for example, can be 106℃, 110℃, 120℃, 125℃, 130℃, 140℃ or a range consisting of any two of them; the reflux ratio is 3.2-4.2, for example, can be 3.2, 3.4, 3.6, 3.8, 4.0, 4.2 or a range consisting of any two of them; the tower diameter is 3700 mm-4400 mm, for example, can be 3700 mm, 3800 mm, 3900 mm, 4000 mm, 4100 mm, 4200 mm, 4300 mm, 4400 mm or a range consisting of any two of them.

[0050] Figure 1 In the rectification system shown, the tower pressure of the crude fractionating tower 1 is 0.15 MPaG-0.22 MPaG, the tower temperature is 60℃-97℃, the reflux ratio is 3.7, and the tower diameter is 4600 mm. It can be seen that the rectification system of the present application can reduce the tower diameter of the crude fractionating tower 1, and the tower pressure and tower temperature of the crude fractionating tower 1 of the present application are higher, which can provide heat for the crude distillation primary tower 2 and the rectification primary tower 5, reducing the steam consumption.

[0051] In some embodiments, the tower pressure of the crude distillation primary tower 2 is 0.23 MPaG-0.25 MPaG, for example, can be 0.23 MPaG, 0.235 MPaG, 0.24 MPaG, 0.245 MPaG, 0.25 MPaG or a range consisting of any two of them; the tower temperature is 58℃-72℃, for example, can be 58℃, 60℃, 62℃, 65℃, 70℃, 72℃ or a range consisting of any two of them; the reflux ratio is 48-64, for example, can be 48, 50, 52, 55, 60, 62, 64 or a range consisting of any two of them; the tower diameter is 5500 mm-6200 mm, for example, can be 5500 mm, 5700 mm, 6000 mm, 6100 mm, 6200 mm or a range consisting of any two of them.

[0052] Figure 1 In the rectification system shown, the tower pressure of the crude distillation primary tower 2 is 0.23 MPaG-0.25 MPaG, the tower temperature is 58℃-72℃, the reflux ratio is 66.4, and the tower diameter is 6400 mm. It can be seen that the rectification system of the present application can reduce the reflux ratio and tower diameter of the crude distillation primary tower 2, which can effectively save the energy consumption in the trichlorosilane rectification process.

[0053] In some embodiments, the column pressure of the primary rectification column 5 is 0.40 MPaG to 0.41 MPaG, for example, can be 0.40 MPaG, 0.402 MPaG, 0.405 MPaG, 0.407 MPaG, 0.41 MPaG or a range consisting of any two of them; the column temperature is 87°C to 88°C, for example, can be 87°C, 87.2°C, 87.5°C, 87.8°C, 88°C or a range consisting of any two of them; the reflux ratio is 105 to 120, for example, can be 105, 107, 110, 105, 120 or a range consisting of any two of them; the column diameter is 4800 mm to 5500 mm, for example, can be 4800 mm, 5000 mm, 5200 mm, 5300 mm, 5500 mm or a range consisting of any two of them.

[0054] Figure 1 In the shown rectification system, the column pressure of the primary rectification column 5 is 0.15 MPaG to 0.16 MPaG, the column temperature is 61°C to 62°C, the reflux ratio is 123.1, and the column diameter is 5700 mm. It can be seen that the rectification system of the present application can reduce the reflux ratio and column diameter of the primary rectification column 5, and can effectively save the energy consumption in the trichlorosilane rectification process.

[0055] In some embodiments of the present application, the column pressure of the primary rectification column 5 is 0.40 MPaG to 0.41 MPaG, for example, can be 0.40 MPaG, 0.402 MPaG, 0.405 MPaG, 0.407 MPaG, 0.41 MPaG or a range consisting of any two of them; the column temperature is 87°C to 88°C, for example, can be 87°C, 87.2°C, 87.5°C, 87.8°C, 88°C or a range consisting of any two of them; the reflux ratio is 105 to 120, for example, can be 105, 107, 110, 105, 120 or a range consisting of any two of them; the column diameter is 4800 mm to 5500 mm, for example, can be 4800 mm, 5000 mm, 5200 mm, 5300 mm, 5500 mm or a range consisting of any two of them.

[0056] Figure 1 In the shown rectification system, the column pressure of the primary rectification column 5 is 0.15 MPaG to 0.16 MPaG, the column temperature is 61°C to 62°C, the reflux ratio is 123.1, and the column diameter is 5700 mm. It can be seen that the rectification system of the present application can reduce the reflux ratio and column diameter of the primary rectification column 5, and can effectively save the energy consumption in the trichlorosilane rectification process.

[0057] In some embodiments, the crude distillation primary column 2 has a column pressure of 0.23-0.25 MPaG, for example, 0.23 MPaG, 0.235 MPaG, 0.24 MPaG, 0.245 MPaG, 0.25 MPaG, or a range defined by any two of them; a column temperature of 58-72°C, for example, 58°C, 60°C, 62°C, 65°C, 70°C, 72°C, or a range defined by any two of them; a reflux ratio of 25-35, for example, 25, 27, 30, 32, 35, or a range defined by any two of them; and a column diameter of 4000-5000 mm, for example, 4000 mm, 4200 mm, 4500 mm, 4700 mm, 5000 mm, or a range defined by any two of them.

[0058] Figure 1 In the shown rectification system, the crude distillation primary column 2 has a column pressure of 0.23-0.25 MPaG, a column temperature of 58-72°C, a reflux ratio of 66.4, and a column diameter of 6400 mm. It can be seen that the rectification system of the present application can reduce the reflux ratio and column diameter of the crude distillation primary column 2, and can effectively save the energy consumption in the trichlorosilane rectification process.

[0059] In some embodiments, the rectification primary column 5 has a column pressure of 0.15-0.16 MPaG, for example, 0.15 MPaG, 0.152 MPaG, 0.155 MPaG, 0.157 MPaG, 0.16 MPaG, or a range defined by any two of them; a column temperature of 61-62°C, for example, 61°C, 61.2°C, 61.5°C, 61.8°C, 62°C, or a range defined by any two of them; a reflux ratio of 55-75, for example, 55, 58, 60, 65, 70, 75, or a range defined by any two of them; and a column diameter of 3700-4700 mm, for example, 3700 mm, 4000 mm, 4200 mm, 4500 mm, 4700 mm, or a range defined by any two of them.

[0060] Figure 1 In the shown rectification system, the rectification primary column 5 has a column pressure of 0.15-0.16 MPaG, a column temperature of 61-62°C, a reflux ratio of 123.1, and a column diameter of 5700 mm. It can be seen that the rectification system of the present application can reduce the reflux ratio and column diameter of the rectification primary column 5, and can effectively save the energy consumption in the trichlorosilane rectification process.

[0061] In some embodiments of the present application, the tower pressure of the crude distillation secondary tower 3 is 0.15-0.19 MPaG, for example, it can be 0.15 MPaG, 0.16 MPaG, 0.17 MPaG, 0.18 MPaG, 0.19 MPaG or a range consisting of any two of them; the tower temperature is 61-65℃, for example, it can be 61℃, 62℃, 63℃, 64℃, 65℃ or a range consisting of any two of them; the reflux ratio is 2.2-3.2, for example, it can be 2.2, 2.5, 2.7, 3.0, 3.2 or a range consisting of any two of them; the tower diameter is 6000-6500 mm, for example, it can be 6000 mm, 6200 mm, 6300 mm, 6400 mm, 6500 mm or a range consisting of any two of them.

[0062] Figure 1 In the shown distillation system, the tower pressure of the crude distillation secondary tower 3 is 0.75-0.79 MPaG, the tower temperature is 111-113℃, the reflux ratio is 4.1, and the tower diameter is 6700 mm. It can be seen that the distillation system of the present application can reduce the tower pressure, tower temperature, reflux ratio and tower diameter of the crude distillation secondary tower 3, which is conducive to the removal of heavy components in the crude distillation secondary tower 3, effectively saves the energy consumption in the trichlorosilane distillation process, and reduces the equipment investment and operating cost.

[0063] In some embodiments of the present application, the tower pressure of the crude distillation tertiary tower 4 is 0.32-0.35 MPaG, for example, it can be 0.32 MPaG, 0.33 MPaG, 0.335 MPaG, 0.34 MPaG, 0.35 MPaG or a range consisting of any two of them; the tower temperature is 80-83℃, for example, it can be 80℃, 81℃, 81.5℃, 82℃, 83℃ or a range consisting of any two of them; the reflux ratio is 2.2-3.2, for example, it can be 2.2, 2.5, 2.7, 3.0, 3.2 or a range consisting of any two of them; the tower diameter is 5100-6000 mm, for example, it can be 5100 mm, 5300 mm, 5500 mm, 5700 mm, 5900 mm, 6000 mm or a range consisting of any two of them.

[0064] Figure 1 In the shown distillation system, the tower pressure of the crude distillation tertiary tower 4 is 0.41-0.44 MPaG, the tower temperature is 88-90℃, the reflux ratio is 3.8, and the tower diameter is 6100 mm. It can be seen that the distillation system of the present application can reduce the tower pressure, tower temperature, reflux ratio and tower diameter of the crude distillation tertiary tower 4, effectively saves the energy consumption in the trichlorosilane distillation process, and reduces the equipment investment and operating cost.

[0065] In the present application, the crude distillation three-stage column 4 is coupled with the last-stage column, so that the column pressure, column temperature, reflux ratio and column diameter of the crude distillation three-stage column 4 can be reduced, and the removal of heavy components in the crude distillation three-stage column 4 is facilitated.

[0066] In some embodiments of the present application, the column pressure of the rectification two-stage column 6 is 0.55 MPaG to 0.57 MPaG, for example, 0.55 MPaG, 0.555 MPaG, 0.56 MPaG, 0.565 MPaG, 0.57 MPaG or a range formed by any two of them; the column temperature is 98℃ to 100℃, for example, 98℃, 98.5℃, 99℃, 99.5℃, 100℃ or a range formed by any two of them; the reflux ratio is 2.9 to 3.9, for example, 2.9, 3.0, 3.2, 3.5, 3.9 or a range formed by any two of them; and the column diameter is 4800mm to 5300mm, for example, 4800mm, 5000mm, 5100mm, 5200mm, 5300mm or a range formed by any two of them.

[0067] Figure 1 In the illustrated rectification system, the column pressure of the rectification two-stage column 6 is 0.28 MPaG to 0.30 MPaG, the column temperature is 76℃ to 78℃, the reflux ratio is 3.2, and the column diameter is 5500mm. It can be seen that the rectification system of the present application can reduce the column diameter of the rectification two-stage column 6.

[0068] In some embodiments, the column pressure of the reduction one-stage column 7 is 0.85 MPaG to 0.87 MPaG, for example, 0.85 MPaG, 0.855 MPaG, 0.86 MPaG, 0.865 MPaG, 0.87 MPaG or a range formed by any two of them; the column temperature is 114℃ to 149℃, for example, 114℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 149℃ or a range formed by any two of them; the reflux ratio is 2.0 to 3.0, for example, 2.0, 2.2, 2.5, 2.7, 3.0 or a range formed by any two of them; and the column diameter is 5700mm to 6800mm, for example, 5700mm, 5900mm, 6000mm, 6200mm, 6500mm, 6800mm or a range formed by any two of them.

[0069] Figure 2In 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 diameter is 5700 to 6800 mm. It can be seen that the first-stage reduction column 7 in the distillation system of this invention has relatively high pressure and temperature, which can provide heat for the second-stage distillation column 6, the third-stage crude distillation column 4, and the second-stage crude distillation column 3, thus reducing steam consumption.

[0070] 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.

[0071] 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.

[0072] The tower temperature in this invention refers to the temperature of the entire tower.

[0073] like Figure 1 As shown, compared to Figure 3 The prior art distillation system shown is different from the distillation system of the present invention. In the distillation system of the present invention, the crude distillation column 1 is coupled to the first-stage distillation column 5, the first-stage distillation column 5 is coupled to the first-stage crude distillation column 2, the first-stage reduction column 7 is coupled to the second-stage distillation column 6, the second-stage distillation column 6 is coupled to the third-stage crude distillation column 4, and the third-stage crude distillation column 4 is coupled to the second-stage crude distillation column 3 (the crude distillation column 1 provides heat to the first-stage distillation column 5, the first-stage distillation column 5 provides heat to the first-stage crude distillation column 2, the first-stage reduction column 7 provides heat to the second-stage distillation column 6, the second-stage distillation column 6 provides heat to the third-stage crude distillation column 4, and the third-stage crude distillation column 4 provides heat to the second-stage crude distillation column 3). The distillation system of the present invention reduces the tower pressure and temperature of the crude distillation stage 2 column 3 and crude distillation stage 3 column 4, reduces the reflux ratio of the crude distillation stage 1 column 2, crude distillation stage 2 column 3, crude distillation stage 3 column 4 and rectification stage 1 column 5, and reduces the tower diameter of the crude distillation stage 1 column 1 column 2 column 2 column 3 column 3 column 4 column 4, rectification stage 1 column 5 and rectification stage 2 column 6. This not only improves the separation efficiency, but also effectively reduces equipment investment and operating costs.

[0074] like Figure 1 As shown, compared to Figure 1Compared with the prior art distillation system shown in the table, the total steam consumption of the distillation system of the present application is reduced, which shows that the distillation system of the present application can effectively save the energy consumption in the distillation process of trichlorosilane.

[0075] Further, Figure 2 The total steam consumption of the distillation system shown in the table is 194.5 t / h; Figure 3 The total steam consumption of the distillation system of the present application shown in the table is 125.6 t / h, Figure 1 The total steam consumption of the distillation system of the present application shown in the table is 125.1 t / h, which can be concluded that, compared with the prior art distillation system shown in the table, Figure 2 Compared with the prior art distillation system shown in the table, the total steam consumption of the distillation system of the present application is reduced, which shows that the distillation system of the present application can effectively save the energy consumption in the distillation process of trichlorosilane.

[0076] In a second aspect, the present application provides a multi-tower differential pressure coupled distillation method for trichlorosilane, which is carried out using the distillation system described above.

[0077] The multi-tower differential pressure coupled distillation method for trichlorosilane of the present application is carried out using the distillation system described above, which can reduce the reflux ratio of the light removal tower, i.e. the first-stage rough distillation tower 2 and the first-stage distillation tower 5, has the advantage of low energy consumption, and is suitable for widespread application.

[0078] In the following, the technical solutions of the present application will be further described in conjunction with specific examples.

[0079] Example 1

[0080] The multi-tower differential pressure coupled distillation system for trichlorosilane of the present embodiment is shown in the table, which includes: Figure 3

[0081] The first-stage rough distillation tower 2, the second-stage rough distillation tower 3, the third-stage rough distillation tower 4, the first-stage distillation tower 5, the second-stage distillation tower 6 and the first-stage reduction tower 7.

[0082] ​The first crude distillation column 2 is provided with a first reboiler 8, the second crude distillation column 3 is provided with a second reboiler 9, the third crude distillation column 4 is provided with a third reboiler 10, the first rectification column 5 is provided with a fourth reboiler 11, and the second rectification column 6 is provided with a fifth reboiler 12.

[0083] The overhead outlet of the coarse separation column 1 is communicated with the first reboiler 8 and the fourth reboiler 11, and then communicated with the raw material inlet of the first crude distillation column 2.

[0084] The bottom outlet of the first crude distillation column 2 is communicated with the raw material inlet of the second crude distillation column 3, the overhead outlet of the second crude distillation column 3 is communicated with the raw material inlet of the third crude distillation column 4, the overhead outlet of the third crude distillation column 4 is communicated with the second reboiler 9 and then communicated with the raw material inlet of the first rectification column 5, the bottom outlet of the first rectification column 5 is communicated with the raw material inlet of the second rectification column 6, the bottom outlet of the second rectification column 6 is communicated with the raw material inlet of the third crude distillation column 4, the overhead outlet of the first reduction column 7 is communicated with the fifth reboiler 12, and the overhead outlet of the second rectification column 6 is communicated with the third reboiler 10, and then goes to the reduction process.

[0085] Example 2

[0086] The three-chlorosilane multi-column differential pressure coupled rectification system of the present embodiment is shown in FIG. 1, which comprises: ​

[0087] The coarse separation column 1, the first crude distillation column 2, the second crude distillation column 3, the third crude distillation column 4, the first rectification column 5, the second rectification column 6, and the first reduction column 7.

[0088] The first crude distillation column 2 is provided with a first reboiler 8, the second crude distillation column 3 is provided with a second reboiler 9, the third crude distillation column 4 is provided with a third reboiler 10, the first rectification column 5 is provided with a fourth reboiler 11, and the second rectification column 6 is provided with a fifth reboiler 12.

[0089] The overhead outlet of the coarse separation column 1 is communicated with the first reboiler 8 and the fourth reboiler 11, and then communicated with the raw material inlet of the first crude distillation column 2.

[0090] The bottom outlet of the first crude distillation column 2 is communicated with the raw material inlet of the second crude distillation column 3, the overhead outlet of the second crude distillation column 3 is communicated with the raw material inlet of the third crude distillation column 4, the overhead outlet of the third crude distillation column 4 is communicated with the second reboiler 9 and then communicated with the raw material inlet of the first rectification column 5, the bottom outlet of the first rectification column 5 is communicated with the raw material inlet of the second rectification column 6, the bottom outlet of the second rectification column 6 is communicated with the raw material inlet of the third crude distillation column 4, the overhead outlet of the first reduction column 7 is communicated with the fifth reboiler 12, and the overhead outlet of the second rectification column 6 is communicated with the third reboiler 10, and then goes to the reduction process.

[0091] ​It should be understood that many of the materials and devices exemplified in this disclosure are articles of manufacture (i.e., articles of manufacture) according to this disclosure. The articles of manufacture can be employed as such to provide advantageous results. The articles of manufacture can also be employed in the practice or testing of the present disclosure. The articles of manufacture can also be employed in the practice or testing of other examples of the present disclosure. The articles of manufacture employed as such for realizing the advantageous results described herein, for practicing the instant disclosure, and for practicing other examples of the instant disclosure will vary depending on the specific context.

Claims

1. A rectification system of trichlorosilane with multi-tower differential pressure coupling, characterized in that, The crude column and the light-removing column are included. The light-removing column has a reboiler, and the overhead outlet of the crude column is communicated with the reboiler of the light-removing column and then communicated with the raw material inlet of the light-removing column.

2. The rectification system of claim 1, wherein, The light-removing column includes a rough distillation primary column and a rectification primary column, the rough distillation primary column has a first reboiler, and the rectification primary column has a fourth reboiler, the overhead outlet of the crude column is communicated with the fourth reboiler and then communicated with the raw material inlet of the rough distillation primary column, and the overhead outlet of the rectification primary column is communicated with the first reboiler.

3. The rectification system of claim 1, wherein, The light-removing column includes a rough distillation primary column and a rectification primary column, the rough distillation primary column has a first reboiler, and the rectification primary column has a fourth reboiler, the overhead outlet of the crude column is communicated with the fourth reboiler and then communicated with the raw material inlet of the rough distillation primary column, and the overhead outlet of the rectification primary column is communicated with the first reboiler.

4. Distillation system according to claim 2 or 3, characterized in that The rectification system further includes a heavy-removing column and a reduction primary column, the heavy-removing column includes a rough distillation secondary column, a rough distillation tertiary column and a rectification secondary column; the rough distillation secondary column has a second reboiler, the rough distillation tertiary column has a third reboiler, and the rectification secondary column has a fifth reboiler; The bottom outlet of the rough distillation primary column is communicated with the raw material inlet of the rough distillation secondary column, the overhead outlet of the rough distillation secondary column is communicated with the raw material inlet of the rough distillation tertiary column, the overhead outlet of the rough distillation tertiary column is communicated with the second reboiler and then communicated with the raw material inlet of the rectification primary column, the bottom outlet of the rectification primary column is communicated with the raw material inlet of the rectification secondary column, the bottom outlet of the rectification secondary column is communicated with the raw material inlet of the rough distillation tertiary column, the overhead outlet of the reduction primary column is communicated with the fifth reboiler, and the overhead outlet of the rectification secondary column is communicated with the third reboiler and then goes to the reduction process.

5. Distillation system according to claim 2 or 4, characterized in that The crude column has a column pressure of 0.65 MPaG to 0.72 MPaG, a column temperature of 106°C to 140°C, a reflux ratio of 3.2 to 4.2, and a column diameter of 3700 mm to 4400 mm; And / or, the rough distillation primary column has a column pressure of 0.23 MPaG to 0.25 MPaG, a column temperature of 58°C to 72°C, a reflux ratio of 48 to 64, and a column diameter of 5500 mm to 6200 mm; And / or, the rectification primary column has a column pressure of 0.40 MPaG to 0.41 MPaG, a column temperature of 87°C to 88°C, a reflux ratio of 105 to 120, and a column diameter of 4800 mm to 5500 mm.

6. Distillation system according to claim 3 or 4, characterized in that The crude column has a column pressure of 0.45 MPaG to 0.52 MPaG, a column temperature of 91°C to 126°C, a reflux ratio of 3.2 to 4.2, and a column diameter of 3900 mm to 4400 mm; And / or, the rough distillation primary column has a column pressure of 0.23 MPaG to 0.25 MPaG, a column temperature of 58°C to 72°C, a reflux ratio of 25 to 35, and a column diameter of 4000 mm to 5000 mm; And / or, the rectification primary column has a column pressure of 0.15 MPaG to 0.16 MPaG, a column temperature of 61°C to 62°C, a reflux ratio of 55 to 75, and a column diameter of 3700 mm to 4700 mm.

7. The rectification system of claim 4, wherein, The tower pressure of the crude distillation secondary tower is 0.15-0.19 MPaG, the tower temperature is 61-65 ℃, the reflux ratio is 2.2-3.2, and the tower diameter is 6000-6500 mm.

8. The rectification system of claim 4, wherein, The tower pressure of the crude distillation tertiary tower is 0.32-0.35 MPaG, the tower temperature is 80-83 ℃, the reflux ratio is 2.3-3.3, and the tower diameter is 5100-6000 mm.

9. The rectification system of claim 4, wherein, The tower pressure of the refined distillation secondary tower is 0.55-0.57 MPaG, the tower temperature is 98-100 ℃, the reflux ratio is 2.9-3.9, and the tower diameter is 4800-5300 mm. The tower pressure of the reduction primary tower is 0.85-0.87 MPaG, the tower temperature is 114-149 ℃, the reflux ratio is 2.0-3.0, and the tower diameter is 5700-6800 mm.

10. A method for rectifying trichlorosilane by multi-column differential pressure coupling, characterized in that, The refined distillation system of any one of claims 1-9 is used.

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