Silicon tetrachloride purification system and silicon tetrachloride purification method

Abstract

The invention provides a high-purity silicon tetrachloride purification system for synthesizing quartz and a corresponding high-purity silicon tetrachloride purification method. The silicon tetrachloride purification system comprises a light component removal tower, an adsorption tower, a purification tower and a gas chromatograph; the light component removal tower is used for carrying out primary rectification purification on a raw material containing silicon tetrachloride and producing a first intermediate material containing silicon tetrachloride; the adsorption tower is communicated with the light component removal tower and is used for adsorbing and purifying the first intermediate material and producing a second intermediate material containing silicon tetrachloride; the purifying tower is used for carrying out secondary rectification and purification on the second intermediate material and producing a third intermediate material containing silicon tetrachloride; the gas chromatograph is communicated with the light component removal tower and / or the purification tower and is used for analyzing the purity of silicon tetrachloride in the light component removal tower and / or the purification tower in real time. The silicon tetrachloride purification method comprises the following steps: analyzing the purity of silicon tetrachloride by using a gas chromatograph, and adjusting the temperature in the light component removal tower and / or the purification tower, the tower top pressure, the tower kettle pressure and the reflux ratio in real time according to the purity analysis.

Description

Technical Field

[0001] The present application relates to the field of material chemistry, and in particular to a silicon tetrachloride purification system and a silicon tetrachloride purification method. Background Art

[0002] With the rapid development of the optical industry, the quality requirements for synthetic quartz are getting higher and higher, especially for its optical uniformity and transmittance. Synthetic quartz uses silicon tetrachloride as the raw material, which is hydrolyzed in a hydrogen-oxygen flame to form silicon dioxide, and finally sintered at high temperature to obtain synthetic quartz. Therefore, the purity of silicon tetrachloride directly affects the quality of synthetic quartz. At present, the raw material of silicon tetrachloride mainly comes from the by-products produced during the production of polycrystalline silicon, which mainly contain trichlorosilane, silicon tetrachloride, phosphorus, boron, metal impurities, etc. The absorption wavelength of phosphorus, boron, and metal impurities and the size of the loss caused by them vary with the valence state, content, and the glass state around them. Their content has a certain relationship with the absorption loss caused by them (0.2~1.1μm). Therefore, it is necessary to strictly purify silicon tetrachloride to remove various harmful impurities to ensure that the optical properties of synthetic quartz are not affected.

[0003] At present, the main methods for purifying silicon tetrachloride include distillation, adsorption, complexation, etc., and the most commonly used one is distillation. In order to ensure the purity is improved, multiple distillation towers are often used in series to obtain high-purity silicon tetrachloride products. Therefore, the advancement of distillation technology plays a vital role in improving product purity and synthetic quartz quality, and can also reduce the investment cost and operating cost of the device.

[0004] How to solve the above problems and provide a high-purity silicon tetrachloride purification method for synthetic quartz and a corresponding high-purity silicon tetrachloride purification system are what those skilled in the art need to consider. Summary of the invention

[0005] In order to solve the above problems, the embodiments of the present application provide a silicon tetrachloride purification system and a silicon tetrachloride purification method, which can provide high-purity silicon tetrachloride for synthetic quartz.

[0006] The present application provides a silicon tetrachloride purification system, comprising: The light-removal tower is used to carry out the first distillation and purification of the raw material containing silicon tetrachloride and produce the first intermediate material containing silicon tetrachloride; an adsorption tower, connected to the light-removal tower, for adsorbing and purifying the first intermediate material and producing a second intermediate material containing silicon tetrachloride; A purification tower, used for performing a second distillation and purification on the second intermediate material, and producing a third intermediate material containing silicon tetrachloride; A gas chromatograph is connected to the light-removal tower and / or the purification tower, and is used for real-time analysis of the purity of silicon tetrachloride in the light-removal tower and / or the purification tower.

[0007] In one embodiment, the gas chromatograph connected to the lightness removal tower is used to perform real-time analysis of the bottom product of the lightness removal tower.

[0008] In one embodiment, the gas chromatograph connected to the purification tower is used to perform real-time analysis on the top extract of the purification tower.

[0009] In one embodiment, there are two gas chromatographs, which are respectively a first gas chromatograph and a second gas chromatograph. The first gas chromatograph is connected to the bottom of the light-removal tower, and the second gas chromatograph is connected to the top of the purification tower.

[0010] In one embodiment, a material containing silicon tetrachloride is taken out from the side of the lightness removal tower and / or the purification tower through a pipeline, the outer side of the pipeline is coated with a heating belt for maintaining the temperature of the material in the pipeline, and the gas chromatograph is connected to the pipeline and is used to detect the material.

[0011] In one embodiment, the gas chromatograph is used to perform purity analysis on the silicon tetrachloride in the lightness removal tower and / or the purification tower, and to adjust at least one of the tower temperature, tower top pressure, tower bottom pressure, and reflux ratio of the lightness removal tower and / or the purification tower in real time according to the result of the purity analysis.

[0012] In one embodiment, there are multiple adsorption towers, and each of the multiple adsorption towers is connected to the light removal tower and the purification tower.

[0013] In one embodiment, the adsorption medium in the adsorption tower includes one or more of alumina, activated carbon, activated silica gel and molecular sieve.

[0014] In one embodiment, a heater is provided in the trays of the lightness removal tower and the purification tower.

[0015] The present application also provides a method for purifying silicon tetrachloride, using the silicon tetrachloride purification system as described in any one of the above embodiments, and the silicon tetrachloride purification method comprises the following steps: The raw material containing silicon tetrachloride is transported to a lightness removal tower for a first distillation and purification, and a first intermediate material containing silicon tetrachloride is produced at the bottom of the lightness removal tower; The first intermediate material is transported to an adsorption tower for adsorption purification, and a second intermediate material containing silicon tetrachloride is produced; The second intermediate material is transported to a purification tower for a second distillation and purification, and a third intermediate material containing silicon tetrachloride is produced at the top of the purification tower; A gas chromatograph connected to the light-removal tower or the purification tower is used to perform purity analysis on the silicon tetrachloride in the light-removal tower and / or the purification tower, and at least one of the tower temperature, tower top pressure, tower bottom pressure, and reflux ratio of the light-removal tower and / or the purification tower is adjusted in real time according to the result of the purity analysis.

[0016] It can be understood that the silicon tetrachloride purification system provided in the embodiment of the present application is composed of a light removal tower, an adsorption tower, a purification tower and a gas chromatograph; wherein the light removal tower is used to remove light components, so that the heavy components enter the adsorption tower for adsorption to reduce the content of metal elements and elements such as phosphorus and boron, and then enter the purification tower for further purification, and finally obtain silicon tetrachloride with a purity of up to 9N level. The silicon tetrachloride purification system and silicon tetrachloride purification method provided in the embodiment of the present application use a gas chromatograph to connect the light removal tower and the purification tower, analyze the purity of the raw materials in real time, and adjust the distillation tower parameters in time to finally obtain high-purity silicon tetrachloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of a silicon tetrachloride purification system provided in an embodiment of the present application.

[0018] Figure 2 A schematic flow chart of a method for purifying silicon tetrachloride provided in an embodiment of the present application.

[0019] Main component symbols Silicon tetrachloride purification system 10 Light removal tower 11 Light removal tower top outlet 111 Lightness removal tower kettle outlet 112 Adsorption tower 12 Purification tower 13 Purification tower top outlet 131 Purification tower kettle outlet 132 Heating plate 14 Gas chromatograph 15 The first gas chromatograph 151 Second gas chromatography device 152 Crude silicon feed pipe 16 Adsorption feed pipe 17 Adsorption discharge pipe 18 The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0020] The following description will refer to the accompanying drawings to more fully describe the content of the present application. Shown in the accompanying drawings are exemplary embodiments of the present application. However, the present application can be implemented in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. Similar reference numerals represent identical or similar components.

[0021] The terms used herein are only used for the purpose of describing specific exemplary embodiments and are not intended to limit the present application. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to also include the plural forms. In addition, when used herein, "including" and / or "comprising" and / or "having", integers, steps, operations, components and / or components, but do not exclude the existence or addition of one or more other features, regions, integers, steps, operations, components and / or groups thereof.

[0022] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. In addition, unless explicitly defined herein, terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant technology and the content of this application, and will not be interpreted as an idealized or overly formal meaning.

[0023] Usually, the raw materials of silicon tetrachloride mainly come from the by-products produced when producing polysilicon, which mainly contain trichlorosilane, phosphorus, boron, metal impurities, etc. The absorption wavelength of phosphorus, boron and metal impurities and the size of the loss caused by them vary with the valence state, content and the glass state around them. There is a certain relationship between their content and the absorption loss caused by them (0.2~1.1μm). Therefore, it is necessary to strictly purify silicon tetrachloride to remove various harmful impurities to ensure that the optical properties of synthetic quartz are not affected. At present, the main methods for purifying silicon tetrachloride are distillation, adsorption, complexation, etc., and the most commonly used is distillation. In order to ensure the purity is improved, multiple distillation towers are often used in series to obtain high-purity silicon tetrachloride products. Therefore, the advancement of distillation technology plays a vital role in improving the purity of the product and the quality of the synthesized quartz.

[0024] Those skilled in the art have conducted some research on the purification of silicon tetrachloride and provided some solutions, but these solutions still face some problems. For example, Chinese patent CN 200310122893.9 discloses a method for producing silicon tetrachloride for optical fiber, but it mainly involves the control of the temperature of the tower top, the tower bottom and the reflux ratio, but it is not controlled during the distillation process, and there is a lack of monitoring during its production process, and the purity of the obtained silicon tetrachloride is only 6N level. For another example, Chinese patent CN201610528311.4 discloses a method for purifying silicon tetrachloride, but the patent only mentions that the theoretical plate number and the actual plate number are calculated according to the initial content of impurities and their final content, and high-purity silicon tetrachloride is obtained accordingly, which mainly involves parameter control during the distillation process, and the final purity of the obtained silicon tetrachloride can only reach 6N level.

[0025] Correspondingly, the present application provides a high-purity silicon tetrachloride purification system for synthetic quartz and a corresponding high-purity silicon tetrachloride purification method. Among them, the silicon tetrachloride purification system includes a lightness removal tower, an adsorption tower, a purification tower and a gas chromatograph; the lightness removal tower is used to perform the first distillation and purification of the raw material containing silicon tetrachloride, and output the first intermediate material containing silicon tetrachloride; the adsorption tower is connected to the lightness removal tower, and is used to perform adsorption and purification of the first intermediate material, and output the second intermediate material containing silicon tetrachloride; the purification tower is used to perform the second distillation and purification of the second intermediate material, and output the third intermediate material containing silicon tetrachloride; the gas chromatograph is connected to the lightness removal tower and / or the purification tower, and is used to analyze the purity of silicon tetrachloride in the lightness removal tower and / or the purification tower in real time. The method for purifying silicon tetrachloride comprises the following steps: conveying a raw material containing silicon tetrachloride to a light-removing tower for a first distillation and purification, and producing a first intermediate material containing silicon tetrachloride in the bottom of the light-removing tower; conveying the first intermediate material to an adsorption tower for adsorption and purification, and producing a second intermediate material containing silicon tetrachloride; conveying the second intermediate material to a purification tower for a second distillation and purification, and producing a third intermediate material containing silicon tetrachloride at the top of the purification tower; performing purity analysis on silicon tetrachloride using a gas chromatograph connected to the light-removing tower and / or the purification tower, and adjusting at least one of the tower temperature, tower top pressure, tower bottom pressure, and reflux ratio of the light-removing tower or the purification tower in real time according to the result of the purity analysis.

[0026] Furthermore, the silicon tetrachloride purification system provided in the embodiment of the present application is composed of a light removal tower, an adsorption tower, a purification tower and a gas chromatograph; wherein the light removal tower is used to remove light components, so that the heavy components enter the adsorption tower for adsorption to reduce the content of metal elements and elements such as phosphorus and boron, and then enter the purification tower for further purification, and finally obtain silicon tetrachloride with a purity of up to 9N level. The silicon tetrachloride purification system and silicon tetrachloride purification method provided in the embodiment of the present application use a gas chromatograph to connect the light removal tower and the purification tower, analyze the purity of the raw materials in real time, and adjust the parameters of the distillation tower in time, and finally obtain high-purity silicon tetrachloride.

[0027] The specific implementation methods of the present application are further described in detail below with reference to the accompanying drawings.

[0028] like Figure 1 As shown, the embodiment of the present application provides a silicon tetrachloride purification system 10 including a lightness removal tower 11, an adsorption tower 12, a purification tower 13 and a gas chromatograph 15; the lightness removal tower 11 is used to perform a first distillation and purification on a raw material containing silicon tetrachloride, and output a first intermediate material containing silicon tetrachloride; the adsorption tower 12 is connected to the lightness removal tower 11, and is used to perform adsorption and purification on the first intermediate material, and output a second intermediate material containing silicon tetrachloride; the purification tower 13 is used to perform a second distillation and purification on the second intermediate material, and output a third intermediate material containing silicon tetrachloride; the gas chromatograph 15 is connected to the lightness removal tower 11 and / or the purification tower 13, and is used to analyze the purity of silicon tetrachloride in the lightness removal tower 11 and / or the purification tower 13 in real time.

[0029] It can be understood that the silicon tetrachloride purification system 10 provided in the embodiment of the present application is composed of a light-removal tower 11, an adsorption tower 12, a purification tower 13 and a gas chromatograph 15; wherein the light-removal tower 11 is used to remove light components, allowing the heavy components to enter the adsorption tower 12 for adsorption to reduce the content of metal elements and elements such as phosphorus and boron, and then enter the purification tower 13 for further purification, and finally obtain silicon tetrachloride with a purity of up to 9N.

[0030] In one embodiment, the light removal tower 11 and the purification tower 13 are both distillation towers. Among them, the distillation tower can include a packed tower and a plate tower, wherein the plate tower includes a floating valve tower, a sieve plate tower, and a bubble cap tower. The light removal tower 11 and the purification tower 13 can select a suitable distillation tower form according to actual needs, which will not be repeated here.

[0031] It can be understood that the principle of common distillation is as follows: the entire distillation process is carried out in a common distillation tower, and the steam generated by the vaporized liquid in the tower flows from bottom to top, and the steam rising to the top of the tower is cooled into liquid and flows from top to bottom. In this continuous gas-liquid two-phase contact process, heat transfer and mass transfer occur. The latent heat released when the steam from below is cooled causes part of the liquid above to be vaporized, and the volatile components are transferred from the liquid phase to the gas phase. At the same time, the steam below releases latent heat and partially condenses into liquid, and the non-volatile components change from the gas phase to the liquid phase. In this way, heat and mass exchange between the gas and liquid phases takes place everywhere inside the distillation tower. When the tower body has a certain height and after a certain period of reflux, the volatile components are continuously transferred from the liquid phase to the gas phase. The steam in the top part of the tower is almost entirely volatile components, that is, low-boiling points. Similarly, the concentration of volatile components in the liquid phase decreases from the top to the bottom of the tower, while the concentration of non-volatile components increases. What is finally obtained at the bottom of the tower is almost entirely non-volatile components, that is, the high-boiling point part. At this time, a dynamic equilibrium is reached inside the entire distillation tower. Different heights correspond to component layers composed of different components, thereby achieving the purpose of separating and purifying the mixture.

[0032] In one embodiment, a heater is disposed in the trays of the lightness removal tower 11 and the purification tower 13 .

[0033] It can be understood that the heating body provided in the light removal tower 11 and the purification tower 13 is configured to ensure the stability of the temperature in the entire distillation tower by heating during the distillation process. The heating body can be a heating plate 14, and the number of heating plates 14 can be multiple, and the multiple heating plates 14 are correspondingly provided in the multi-layer tower plates of the light removal tower 11 and the purification tower 13.

[0034] In this embodiment, the light component removal tower 11 is used to remove light components (such as trichlorosilane, etc.), and the heavy components enter the adsorption tower 12 for adsorption to reduce the content of metal elements and elements such as phosphorus and boron, and then enter the purification tower 13 for further purification, and finally obtain silicon tetrachloride with a purity of up to 9N level.

[0035] It can be understood that the silicon tetrachloride prepared in this application has a purity of 9N level and can be used as a raw material for synthetic quartz, and can be used in optical fiber, semiconductor and other industries. The silicon tetrachloride prepared in this application is used as a raw material for synthetic quartz, and is obtained by high-temperature hydrolysis deposition to obtain synthetic quartz with high transmittance and better optical uniformity index.

[0036] In one embodiment, the gas chromatograph 15 connected to the lightness removal tower 11 is used to perform real-time analysis on the bottom product of the lightness removal tower 11 .

[0037] In one embodiment, the gas chromatograph 15 connected to the purification tower 13 is used to perform real-time analysis on the top product of the purification tower 13 .

[0038] In one embodiment, the two gas chromatographs 15 are respectively a first gas chromatograph 151 and a second gas chromatograph 152 . The first gas chromatograph 151 is connected to the bottom of the light-removal tower 11 , and the second gas chromatograph 152 is connected to the top of the purification tower 13 .

[0039] In one embodiment, a material containing silicon tetrachloride is taken out from the side of the lightness removal tower 11 and / or the purification tower 13 through a pipeline, and the outer side of the pipeline is coated with a heating belt to maintain the temperature of the material in the pipeline. A gas chromatograph 15 is connected to the pipeline and is used to detect the material.

[0040] In one embodiment, the gas chromatograph 15 is used to perform purity analysis on the silicon tetrachloride in the lightness removal tower 11 and / or the purification tower 13, and to adjust at least one of the tower temperature, tower top pressure, tower bottom pressure, and reflux ratio of the lightness removal tower 11 or the purification tower 13 in real time according to the result of the purity analysis.

[0041] In one embodiment, for the adjustment of the lightness removal tower 11, after the gas chromatograph 15 (first gas chromatography device 151) matched therewith extracts data for analysis, if the target product concentration is lower than the target value, the reflux ratio of the lightness removal tower 11 is increased, or the bottom temperature of the lightness removal tower 11 is increased, or the whole tower pressure of the lightness removal tower 11 is reduced, or the reflux ratio, bottom temperature and whole tower pressure of the lightness removal tower 11 are adjusted simultaneously to increase the product concentration to the target value.

[0042] In one embodiment, for the adjustment of the purification tower 13, after the gas chromatograph 15 (the second gas chromatograph device 152) matched therewith extracts data for analysis, if the target product concentration is lower than the target value, the reflux ratio of the purification tower 13 is reduced, or the top temperature of the purification tower 13 is increased, or the whole tower pressure of the purification tower 13 is increased, or the reflux ratio, the top temperature, and the whole tower pressure of the purification tower 13 are adjusted simultaneously to increase the product concentration to the target value.

[0043] It can be understood that the material containing silicon tetrachloride is taken out from the side of the light-removal tower 11 through a pipeline, and a heating belt is provided outside the pipeline to ensure the temperature of the raw material. The material is then transported to the industrial gas chromatograph 15 for real-time analysis of the purity of silicon tetrachloride. Through the purity analysis, the temperature, top pressure, bottom pressure and reflux ratio of the light-removal tower 11 are adjusted in real time to maintain the concentration of silicon tetrachloride in the taken-out material at a relatively high level, for example, the purity reaches 9N level.

[0044] Similarly, materials containing silicon tetrachloride are extracted from the side of the purification tower 13 through a pipeline. A heating belt is provided outside the pipeline to ensure the temperature of the raw material. The raw material is then transported to an industrial gas chromatograph 15 for real-time analysis of the purity of silicon tetrachloride. Through the purity analysis, the temperature, top pressure, bottom pressure, and reflux ratio of the purification tower 13 are adjusted in real time to maintain the concentration of silicon tetrachloride in the extracted material at a relatively high level, for example, the purity reaches 9N level.

[0045] In this embodiment, the first gas chromatograph 151 and the second gas chromatograph 152 may be the same industrial gas chromatograph.

[0046] It is understandable that the gas chromatograph 15 may be an industrial gas chromatograph 15, or the gas chromatograph 15 may be an infrared gas chromatograph 15. In other embodiments, the gas chromatograph 15 may also be other gas chromatographs 15 capable of real-time analysis, which will not be described in detail herein.

[0047] In one embodiment, there are multiple adsorption towers 12 , each of which is connected to the lightness removal tower 11 and the purification tower 13 , and an adsorption medium is disposed in the adsorption tower 12 .

[0048] In this embodiment, there are two adsorption towers 12, and the two adsorption towers 12 are configured to serve as substitutes for each other, that is, when one adsorption tower 12 is in working state, the other adsorption tower 12 can be in standby state or maintenance state.

[0049] It is understandable that, in general, only one adsorption tower 12 is required to work during production, and the other adsorption tower 12 is a standby, so that the adsorption medium in the adsorption tower 12 needs to be replaced. For example, when replacing the adsorption medium in one adsorption tower 12, the other adsorption tower 12 can still work normally, so as not to affect normal production; in other embodiments, the number of adsorption towers 12 can also be multiple, and several of the multiple adsorption towers 12 can be in working state, while other adsorption towers 12 can be in standby or maintenance state. After adsorption by the adsorption tower 12, the metal elements, phosphorus, and boron elements in silicon tetrachloride are further reduced, which is convenient for further transmission to the purification tower 13.

[0050] In one embodiment, the adsorption medium in the adsorption tower 12 includes one or more of alumina, activated carbon, activated silica gel and molecular sieve. Further, the adsorption medium is preferably activated silica gel or molecular sieve.

[0051] In this embodiment, the silicon tetrachloride purification system 10 provided in the embodiment of the present application includes a light-removal tower 11, two adsorption towers 12, a purification tower 13, two gas chromatographs 15 and several transmission pipelines; wherein the transmission pipeline includes a crude silicon feed pipe 16, an adsorption feed pipe 17, and an adsorption discharge pipe 18.

[0052] In the present embodiment, the crude silicon feed pipe 16 is connected to the light-removing tower 11 and is roughly connected to the middle part of the light-removing tower 11; a light-removing tower top extraction port 111 is correspondingly provided at the top of the light-removing tower 11, and the light-removing tower top extraction port 111 is mainly used to extract trichlorosilane; a light-removing tower kettle extraction port 112 is correspondingly provided at the bottom of the light-removing tower 11, and the light-removing tower kettle extraction port 112 is mainly used to extract materials containing silicon tetrachloride; the adsorption feed pipeline 17 is connected to the light-removing tower kettle extraction port 112 and is further connected to the two adsorption towers 12 respectively, and the adsorption discharge pipeline 18 is respectively connected to the two adsorption towers 12 and is further connected to the purification tower 13; a purification tower top extraction port 131 is correspondingly provided at the top of the purification tower 13, and the purification tower top extraction port 131 is mainly used to extract products containing silicon tetrachloride (high-purity silicon tetrachloride); a purification tower kettle extraction port 132 is correspondingly provided at the bottom of the purification tower 13 for extracting other substances.

[0053] In the present embodiment, the crude silicon tetrachloride raw material enters the lightness removal tower 11 from the crude silicon feed pipe 16, and is distilled in the lightness removal tower 11 by utilizing the different boiling points of each component, and trichlorosilane and other light components are extracted at the top extraction port 111 of the lightness removal tower, and the other part continues to circulate in the lightness removal tower 11, and extracts the material containing silicon tetrachloride by side extraction at the extraction port 112 of the lightness removal tower reactor, at which time the material containing silicon tetrachloride also contains metal impurities and phosphorus and boron compounds thereof. The silicon tetrachloride material containing metal impurities and phosphorus and boron compounds thereof is passed into the adsorption tower 12, and the metal impurities and phosphorus and boron compounds thereof are adsorbed by the adsorption tower 12, and the material containing silicon tetrachloride is further extracted, and then introduced into the purification tower 13 for further purification. Distillation is performed in the purification tower 13 by utilizing the different boiling points of each component, and high-purity silicon tetrachloride is extracted by side extraction at the extraction port 131 of the top of the purification tower, and other components are extracted at the extraction port 132 of the purification tower reactor.

[0054] It can be understood that the silicon tetrachloride purification system 10 provided in the embodiment of the present application has at least the following advantages: a gas phase industrial chromatograph (gas chromatograph 15) is used to perform real-time analysis on the produced material from the bottom of the light removal tower 11 and / or the produced material from the top of the purification tower 13, so as to facilitate timely adjustment of the bottom and top temperatures and reflux ratios of the light removal tower 11 and / or the purification tower 13, and finally obtain silicon tetrachloride raw materials with a purity level of 9N; after purification in the light removal tower 11, the metal elements and nitrogen, phosphorus and boron elements in the remaining heavy components are adsorbed, and then further purification is performed in the purification tower 13 to greatly improve the purity of silicon tetrachloride; the light removal tower 11 and / or the purification tower 13 have a heating body in the tray, which can ensure the temperature stability of the light removal tower 11 and / or the purification tower 13, thereby ensuring the purification efficiency and purity.

[0055] Further integration Figure 2As shown, the embodiment of the present application also provides a method for purifying silicon tetrachloride, using a silicon tetrachloride purification system as in any one of the above embodiments, the silicon tetrachloride purification method comprises the following steps: The raw material containing silicon tetrachloride is transported to a lightness removal tower for a first distillation and purification, and a first intermediate material containing silicon tetrachloride is produced in the bottom of the lightness removal tower; The first intermediate material is transported to an adsorption tower for adsorption purification, and a second intermediate material containing silicon tetrachloride is produced; The second intermediate material is transported to a purification tower for a second distillation and purification, and a third intermediate material containing silicon tetrachloride is produced at the top of the purification tower; A gas chromatograph connected to the lightness removal tower and / or the purification tower is used to perform purity analysis on the silicon tetrachloride in the lightness removal tower and / or the purification tower, and at least one of the tower temperature, tower top pressure, tower bottom pressure, and reflux ratio of the lightness removal tower or the purification tower is adjusted in real time according to the result of the purity analysis.

[0056] It can be understood that the silicon tetrachloride purification system and silicon tetrachloride purification method provided in the embodiments of the present application use a gas chromatograph to connect the lightness removal tower and the purification tower, and analyze the purity of the raw materials in real time, so as to adjust the distillation tower parameters in time and finally obtain high-purity silicon tetrachloride.

[0057] Embodiment 1: After being preheated, crude silicon tetrachloride enters from the middle of the light removal tower. The number of light removal tower plates is 60, and the crude silicon tetrachloride feeding position is the 29th tower plate from the top. The top temperature of the light removal tower is controlled at 86℃ to 87℃, and the bottom temperature of the light removal tower is controlled at 116℃ to 117℃; the whole tower pressure of the light removal tower is controlled at 0.4Mpa to 0.5Mpa, and the reflux ratio is controlled between 20:1 and 18:1. After entering the light removal tower, the crude silicon tetrachloride is continuously evaporated and refluxed. A portion of silicon tetrachloride material is extracted from the side of the tower kettle of the light-removal tower in real time for real-time analysis of the concentration of the target product. The material extracted from the side of the tower kettle of the light-removal tower is sent to an industrial gas chromatograph through a pipeline. This pipeline has a heating function, and the concentration of silicon tetrachloride in the extracted material is analyzed in real time by the industrial gas chromatograph. When the concentration of silicon tetrachloride is low, the pressure of the entire tower, the temperature of the tower kettle at the top of the tower, and the reflux ratio are adjusted. At the same time, each tower plate has a heating function during the production process, which can quickly adjust the temperature distribution of the entire tower to ensure that trichlorosilane can be effectively separated from crude silicon tetrachloride. The light-removal tower extracts trichlorosilane from the top of the tower and silicon tetrachloride from the tower kettle. The extracted material from the tower kettle also contains metal impurities and their phosphorus and boron compounds.

[0058] After the silicon tetrachloride is extracted from the light-removal tower, it is adsorbed in the adsorption tower to greatly reduce the content of metal impurities, phosphorus and boron. The adsorption medium of the adsorption tower is selected from activated silica gel and molecular sieve; since the adsorption medium needs to be replaced regularly, in order not to affect its production, one adsorption tower is often used and the other is used as a switch, but when the adsorption medium needs to be replaced, the other is switched to another adsorption tower to work.

[0059] Furthermore, after adsorption in the adsorption tower, it enters the middle part of the purification tower. The number of plates in the purification tower is 75, and the feed position is the 35th plate from the top. The top temperature is controlled at 85°C to 86°C, the bottom temperature is controlled at 112°C to 113°C, the whole tower pressure is controlled at 0.3 Mpa to 0.4 Mpa, and the reflux ratio is controlled between 30:1 and 28:1. The industrial gas chromatograph analyzes the top extract to control the parameters of the whole tower in real time. Finally, the purity of silicon tetrachloride after extraction can reach 9N level.

[0060] Embodiment 2: After being preheated, crude silicon tetrachloride enters from the middle of the light removal tower. The number of light removal tower plates is 60, and the crude silicon tetrachloride feeding position is the 29th tower plate from the top. The top temperature of the light removal tower is controlled at 87℃ to 90℃, and the top tower kettle temperature of the light removal tower is controlled at 115℃ to 116℃; the whole tower pressure of the light removal tower is controlled at 0.3Mpa to 0.35Mpa, and the reflux ratio is controlled between 19:1 and 16:1. After entering the light removal tower, the crude silicon tetrachloride is continuously evaporated and refluxed. A portion of the product is extracted from the side of the tower kettle of the light-removal tower in real time for real-time analysis of the concentration of the target product. The product is extracted from the side of the tower kettle of the light-removal tower and sent to an industrial gas chromatograph through a pipeline. The pipeline has a heating function, and the concentration of silicon tetrachloride extracted from the extracted material is analyzed in real time by the industrial gas chromatograph. When the concentration of silicon tetrachloride is low, the pressure of the entire tower, the temperature of the tower kettle at the top of the tower, and the reflux ratio are adjusted. At the same time, each tower plate has a heating function during the production process, which can quickly adjust the temperature distribution of the entire tower to ensure that trichlorosilane can be effectively separated from crude silicon tetrachloride. The light-removal tower extracts trichlorosilane from the top of the tower and silicon tetrachloride from the tower kettle. The extracted material from the tower kettle also contains metal impurities and their phosphorus and boron compounds.

[0061] After the silicon tetrachloride is extracted from the light-removal tower, it is adsorbed in the adsorption tower to greatly reduce the content of metal impurities, phosphorus and boron. The adsorption medium of the adsorption tower is selected from activated silica gel and molecular sieve; since the adsorption medium needs to be replaced regularly, in order not to affect its production, one adsorption tower is often used and the other is used as a switch, but when the adsorption medium needs to be replaced, the other is switched to another adsorption tower to work.

[0062] Furthermore, after adsorption in the adsorption tower, it enters the middle part of the purification tower. The number of plates in the purification tower is 75, and the feed position is the 35th plate from the top. The top temperature is controlled at 86°C to 87°C, the bottom temperature is controlled at 112°C to 113°C, the whole tower pressure is controlled at 0.3 Mpa to 0.35 Mpa, and the reflux ratio is controlled between 30:1 and 27:1. The industrial gas chromatograph analyzes the top extract to control the parameters of the whole tower in real time. Finally, the purity of silicon tetrachloride after extraction can reach 9N level.

[0063] Embodiment 3: After being preheated, the crude silicon tetrachloride enters the middle of the light removal tower. The number of plates of the light removal tower is 60, and the feeding position of the crude silicon tetrachloride is the 29th plate from the top. The top temperature of the light removal tower is controlled at 85℃ to 87℃, and the top kettle temperature of the light removal tower is controlled at 116℃ to 117℃; the whole tower pressure of the light removal tower is controlled at 0.2Mpa to 0.3Mpa, and the reflux ratio is controlled between 16:1 and 10:1. After entering the light removal tower, the crude silicon tetrachloride is continuously evaporated and refluxed. A portion of the product is extracted from the side of the tower kettle of the light-removal tower in real time for real-time analysis of the concentration of the target product. The product is extracted from the side of the tower kettle of the light-removal tower and sent to an industrial gas chromatograph through a pipeline. The pipeline has a heating function, and the concentration of silicon tetrachloride extracted from the extracted material is analyzed in real time by the industrial gas chromatograph. When the concentration of silicon tetrachloride is low, the pressure of the entire tower, the temperature of the tower kettle at the top of the tower, and the reflux ratio are adjusted. At the same time, each tower plate has a heating function during the production process, which can quickly adjust the temperature distribution of the entire tower to ensure that trichlorosilane can be effectively separated from crude silicon tetrachloride. The light-removal tower extracts trichlorosilane from the top of the tower and silicon tetrachloride from the tower kettle. The extracted material from the tower kettle also contains metal impurities and their phosphorus and boron compounds.

[0064] After the silicon tetrachloride is extracted from the light-removal tower, it is adsorbed in the adsorption tower to greatly reduce the content of metal impurities, phosphorus and boron. The adsorption medium of the adsorption tower is selected from activated silica gel and molecular sieve; since the adsorption medium needs to be replaced regularly, in order not to affect its production, one adsorption tower is often used and the other is used as a switch, but when the adsorption medium needs to be replaced, the other is switched to another adsorption tower to work.

[0065] Furthermore, after adsorption in the adsorption tower, it enters the middle part of the purification tower. The number of plates in the purification tower is 75, and the feed position is the 35th plate from the top. The top temperature is controlled at 84°C to 87°C, the bottom temperature is controlled at 110°C to 113°C, the whole tower pressure is controlled at 0.3 Mpa to 0.5 Mpa, and the reflux ratio is controlled between 25:1 and 15:1. The industrial gas chromatograph analyzes the top extract to control the parameters of the whole tower in real time. Finally, the purity of silicon tetrachloride after extraction can reach 9N level.

[0066] Comparative Example: After being preheated, crude silicon tetrachloride enters the middle of the light removal tower. The number of light removal tower plates is 60, and the crude silicon tetrachloride feed position is the 29th tower plate from the top. The top temperature of the light removal tower is controlled at 85℃ to 87℃, and the tower bottom temperature of the light removal tower is controlled at 115℃ to 116℃; the whole tower pressure of the light removal tower is controlled at 0.2Mpa to 0.3Mpa, and the reflux ratio is controlled between 15:1 and 25:1. After entering the light removal tower, the crude silicon tetrachloride is continuously evaporated and refluxed. The light removal tower produces trichlorosilane from the top of the tower and silicon tetrachloride from the bottom of the tower. The materials produced from the bottom of the tower also contain metal impurities and their phosphorus and boron compounds.

[0067] After the silicon tetrachloride is extracted from the light-removal tower, it is adsorbed in the adsorption tower to greatly reduce the content of metal impurities, phosphorus and boron. The adsorption medium of the adsorption tower is selected from activated silica gel and molecular sieve; since the adsorption medium needs to be replaced regularly, in order not to affect its production, one adsorption tower is often used and the other is used as a switch, but when the adsorption medium needs to be replaced, the other is switched to another adsorption tower to work.

[0068] After adsorption, it enters the middle part of the purification tower. The number of plates of the light-removal tower is 75. The feed position is the 35th plate from the top. The top temperature is controlled at 87°C to 89°C, the bottom temperature is controlled at 113°C to 115°C, the whole tower pressure is controlled at 0.3Mpa to 0.35Mpa, and the reflux ratio is controlled between 30:1 and 20:1. During this process, the industrial gas chromatographs of the light-removal tower and the purification tower are closed and under artificial control. Finally, the purity of the produced silicon tetrachloride reaches 6N level.

[0069] In the above, the specific embodiments of the present application are described with reference to the accompanying drawings. However, those skilled in the art will appreciate that various changes and substitutions may be made to the specific embodiments of the present application without departing from the scope of the present application. These changes and substitutions are all within the scope defined by the present application.

Claims

1. A silicon tetrachloride purification system, characterized in that: include: The light-removal tower is used to carry out the first distillation and purification of the raw material containing silicon tetrachloride and produce the first intermediate material containing silicon tetrachloride; an adsorption tower, connected to the light-removal tower, for adsorbing and purifying the first intermediate material and producing a second intermediate material containing silicon tetrachloride; A purification tower, used for performing a second distillation and purification on the second intermediate material, and producing a third intermediate material containing silicon tetrachloride; A gas chromatograph is connected to the light-removal tower and / or the purification tower, and is used for real-time analysis of the purity of silicon tetrachloride in the light-removal tower and / or the purification tower.

2. The silicon tetrachloride purification system according to claim 1, characterized in that: The gas chromatograph connected to the lightness removal tower is used for real-time analysis of the bottom product of the lightness removal tower.

3. The silicon tetrachloride purification system according to claim 1, characterized in that: The gas chromatograph connected to the purification tower is used for real-time analysis of the top extraction material of the purification tower.

4. The silicon tetrachloride purification system according to claim 1, characterized in that: There are two gas chromatographs, which are respectively a first gas chromatograph and a second gas chromatograph. The first gas chromatograph is connected to the bottom of the light-removal tower, and the second gas chromatograph is connected to the top of the purification tower.

5. The silicon tetrachloride purification system according to claim 1, characterized in that: The material containing silicon tetrachloride is taken out through a pipeline at the side of the light-removal tower and / or the purification tower. The outer side of the pipeline is coated with a heating belt for maintaining the temperature of the material in the pipeline. The gas chromatograph is connected to the pipeline and is used to detect the material.

6. The silicon tetrachloride purification system according to claim 1, characterized in that: The gas chromatograph is used to perform purity analysis on the silicon tetrachloride in the light-removal tower and / or the purification tower, and to adjust at least one of the tower temperature, tower top pressure, tower bottom pressure, and reflux ratio of the light-removal tower and / or the purification tower in real time according to the result of the purity analysis.

7. The silicon tetrachloride purification system according to claim 1, characterized in that: There are multiple adsorption towers, and each of the multiple adsorption towers is connected to the light removal tower and the purification tower.

8. The silicon tetrachloride purification system according to claim 1, characterized in that: The adsorption medium in the adsorption tower includes one or more of alumina, activated carbon, activated silica gel and molecular sieve.

9. The silicon tetrachloride purification system according to claim 1, characterized in that: A heating body is arranged in the tower plates of the lightness removal tower and the purification tower.

10. A method for purifying silicon tetrachloride, characterized in that: Using the silicon tetrachloride purification system as described in any one of claims 1 to 9, the silicon tetrachloride purification method comprises the following steps: The raw material containing silicon tetrachloride is transported to a lightness removal tower for a first distillation and purification, and a first intermediate material containing silicon tetrachloride is produced at the bottom of the lightness removal tower; The first intermediate material is transported to an adsorption tower for adsorption purification, and a second intermediate material containing silicon tetrachloride is produced; The second intermediate material is transported to a purification tower for a second distillation and purification, and a third intermediate material containing silicon tetrachloride is produced at the top of the purification tower; A gas chromatograph connected to the light-removal tower and / or the purification tower is used to perform purity analysis on the silicon tetrachloride in the light-removal tower and / or the purification tower, and at least one of the tower temperature, tower top pressure, tower bottom pressure, and reflux ratio of the light-removal tower or the purification tower is adjusted in real time according to the result of the purity analysis.

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