CN116553559A - Method and system for controlling content of carbon impurities in disilicon for reduction process - Google Patents
Method and system for controlling content of carbon impurities in disilicon for reduction process Download PDFInfo
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- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 279
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 278
- 239000012535 impurity Substances 0.000 title claims abstract description 185
- 238000011946 reduction process Methods 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 55
- NTQGILPNLZZOJH-UHFFFAOYSA-N disilicon Chemical compound [Si]#[Si] NTQGILPNLZZOJH-UHFFFAOYSA-N 0.000 title claims description 29
- 238000000926 separation method Methods 0.000 claims abstract description 166
- 239000002994 raw material Substances 0.000 claims abstract description 113
- 239000005046 Chlorosilane Substances 0.000 claims abstract description 69
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical compound Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 claims abstract description 69
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 66
- 229920005591 polysilicon Polymers 0.000 claims abstract description 56
- 239000003463 adsorbent Substances 0.000 claims abstract description 28
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 20
- 239000010703 silicon Substances 0.000 claims abstract description 20
- 230000000295 complement effect Effects 0.000 claims abstract description 7
- 238000006722 reduction reaction Methods 0.000 claims description 74
- 239000001257 hydrogen Substances 0.000 claims description 66
- 229910052739 hydrogen Inorganic materials 0.000 claims description 66
- 238000011084 recovery Methods 0.000 claims description 60
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 58
- 230000009467 reduction Effects 0.000 claims description 56
- 239000007789 gas Substances 0.000 claims description 52
- 238000001179 sorption measurement Methods 0.000 claims description 33
- 238000004064 recycling Methods 0.000 claims description 29
- 239000000306 component Substances 0.000 claims description 28
- 238000005984 hydrogenation reaction Methods 0.000 claims description 21
- 238000005262 decarbonization Methods 0.000 claims description 13
- 230000008676 import Effects 0.000 claims description 12
- 239000012533 medium component Substances 0.000 claims description 11
- 230000000153 supplemental effect Effects 0.000 claims description 10
- 150000002431 hydrogen Chemical class 0.000 claims description 8
- 230000008569 process Effects 0.000 abstract description 25
- 230000008901 benefit Effects 0.000 abstract description 5
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 179
- 239000005052 trichlorosilane Substances 0.000 description 179
- MROCJMGDEKINLD-UHFFFAOYSA-N dichlorosilane Chemical compound Cl[SiH2]Cl MROCJMGDEKINLD-UHFFFAOYSA-N 0.000 description 163
- 238000004519 manufacturing process Methods 0.000 description 21
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 19
- 239000005049 silicon tetrachloride Substances 0.000 description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 18
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 11
- 239000000047 product Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 238000009835 boiling Methods 0.000 description 7
- 238000001514 detection method Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 3
- PZPGRFITIJYNEJ-UHFFFAOYSA-N disilane Chemical compound [SiH3][SiH3] PZPGRFITIJYNEJ-UHFFFAOYSA-N 0.000 description 3
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 3
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000005137 deposition process Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- UOCLXMDMGBRAIB-UHFFFAOYSA-N 1,1,1-trichloroethane Chemical compound CC(Cl)(Cl)Cl UOCLXMDMGBRAIB-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 238000007323 disproportionation reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/08—Compounds containing halogen
- C01B33/107—Halogenated silanes
- C01B33/10778—Purification
- C01B33/10784—Purification by adsorption
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/021—Preparation
- C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
- C01B33/03—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition of silicon halides or halosilanes or reduction thereof with hydrogen as the only reducing agent
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The application relates to a method and a system for controlling the content of carbon impurities in disilicide for a reduction process, which are characterized in that recovered chlorosilane is introduced into a first separation tower for separation treatment, complementary TCS and recovered TCS are introduced into a second separation tower for carbon removal treatment, and the first recovered DCS and/or the second recovered DCS are adsorbed and removed by a special adsorbent. The method has the advantages that the separation treatment is carried out on the recovered chlorosilane through the separation tower, then the deep carbon removal is carried out on the raw material TCS, the raw material TCS is prevented from introducing carbon impurities into the reduction process, meanwhile, on the basis of increasing the introduction of no carbon impurities in the recovered DCS, the carbon impurities in the recovered DCS are removed, the purity of the raw material DCS is ensured, and the carbon impurities accumulated in a circulating mode can be removed from the reduction process through the carbon removal step of the recovered DCS, so that the recovered DCS is free of carbon and recycled, the purity of polysilicon is prevented from being influenced due to the fact that the carbon impurities in the two silicon are more in the original process, and the produced polysilicon is low in carbon impurity content and high in quality.
Description
Technical Field
The application relates to the technical field of polysilicon production, in particular to a method and a system for controlling the content of carbon impurities in disilicon for a reduction process.
Background
The industrialization of the polysilicon in China starts from the 50 th century and rapidly develops in the beginning of the 21 st century, and along with technological innovation and technological progress, the competition of the polysilicon industry is more and more vigorous, how to reduce the production cost of the polysilicon and improve the production efficiency of the polysilicon is a key to the polysilicon industry. Mixtures of Trichlorosilane (TCS), silicon Tetrachloride (STC) and Dichlorosilane (DCS) are known in the polysilicon industry as chlorosilanes.
The reduction process is the most important link in the polysilicon production process, the core equipment of the process is a reduction furnace, the control requirements of the furnace type on a temperature field and a flow field in the polysilicon deposition process are very high, the uniformity of the polysilicon deposition process needs to be ensured, otherwise, the conditions of 'atomization', 'grounding', even 'furnace reversing', and the like can occur. How to make the reduction process run stably and efficiently is a problem that the polysilicon industry is always exploring.
The traditional polysilicon production process is to purify TCS, then mix with hydrogen and enter a reduction furnace to react under the high temperature condition to prepare polysilicon. It was later found that the reduction reaction can be accelerated by the small amount of DCS contained in TCS, and that the reduction reaction can be performed faster and consumes less energy due to the higher activity of DCS. In the prior art, the reduction tail gas is generally recovered and separated to obtain DCS, the recovered DCS is used as the Disilicon (DCS) for the reduction process to be mixed with TCS, and the mixed DCS is mixed with hydrogen to enter a reduction furnace for reduction reaction to prepare polysilicon, so that the recovery and recycling of the DCS are realized.
Since the part of recovered DCS is recovered from the reduction tail gas, and the reduction tail gas is the product of the reduction process of hydrogen, TCS and DCS, the hydrogen and the DCS are mainly outsourced high-purity hydrogen and high-purity DCS in the initial stage of the reduction process, and basically have no carbon impurities or have little carbon impurities, the carbon impurities in the reduction tail gas are mainly introduced by the TCS, so that the part of recovered DCS contains the carbon impurities and are mainly introduced by the TCS. The part of recovered DCS containing carbon impurities is used as two silicon for the reduction process for recycling, carbon impurities are inevitably introduced into the reduction process, and new carbon impurities are continuously introduced into TCS, so that the carbon impurities are circularly accumulated in the reduction process, the carbon impurities in the reduction tail gas are gradually increased, the carbon impurities in the recovered DCS are further increased, and the like, along with repeated recovery of DCS and repeated recycling of two silicon for the reduction process, the carbon impurities in the reduction tail gas are increasingly accumulated in the reduction process, the carbon impurities in the recovered DCS are increasingly increased, the carbon impurities in the recovered DCS are also increasingly increased, the carbon impurities are also increasingly increased in content, and if the part of recovered DCS with the increasingly increased carbon impurities is used as two silicon for the reduction process, the purity of polysilicon is inevitably influenced, so that the produced polysilicon has high carbon impurities and low quality.
Disclosure of Invention
Based on this, in the prior art, it is necessary to recycle the recovered DCS as the two silicon for the reduction process, carbon impurities are introduced into the reduction process, and new carbon impurities are continuously introduced into the TCS, so that the carbon impurities are accumulated in the reduction process in a circulating manner, and if the recovered DCS with an increasingly higher carbon impurity content is further used as the two silicon for the reduction process, the purity of the polysilicon is affected, so that the produced polysilicon has a high carbon impurity content and a low quality. The method and the system for controlling the content of the carbon impurities in the two silicon for the reduction process are provided, the raw material TCS is deeply decarbonized, so that the raw material TCS is prevented from introducing the carbon impurities into the reduction process, meanwhile, on the basis of increasing the introduction of no carbon impurities in the recovered DCS, the carbon impurities in the recovered DCS are removed, the purity of the raw material DCS is ensured, and the circularly accumulated carbon impurities can be removed from the reduction process through the step of removing the carbon in the recovered DCS, so that the recovered DCS is free of carbon and recycled, the purity of polysilicon is prevented from being influenced due to the fact that the carbon impurities in the two silicon for the original process are more, and the produced polysilicon is low in carbon impurity content and high in quality.
A method for controlling the content of carbon impurities in disilicon for reduction process comprises the following steps:
S10, separating and recycling the reduction tail gas to obtain recovered chlorosilane, introducing the recovered chlorosilane into a separation tower for separation treatment, wherein the separation tower can discharge light components in the recovered chlorosilane from the top of the tower, medium components are discharged from the side of the tower, heavy components are discharged from the bottom of the tower, and a first recovered DCS and a recovered TCS are respectively extracted from the top and the side of the tower of the separation tower;
s20, introducing the supplementary TCS and the recovered TCS into a separation two-tower for decarbonizing treatment, wherein the separation two-tower can discharge light components in the supplementary TCS and the recovered TCS from the tower top, medium components from the tower side, heavy components from the tower bottom, and respectively extracting second recovered DCS and raw material TCS from the tower top and the tower side of the separation two-tower;
s30, adsorbing the first recovery DCS and/or the second recovery DCS by a special adsorbent to remove carbon, so as to obtain a raw material DCS after carbon removal;
s40, mixing the raw material DCS and the raw material TCS in proportion to serve as raw materials for a reduction process, and enabling the raw materials to enter a reduction furnace for reduction reaction to prepare the polycrystalline silicon.
Preferably, in the above method for controlling carbon impurity content in disilicon for reduction process, in the step S20, the carbon removing treatment is performed by passing the supplementary TCS and the recovered TCS into a separation two-column, and the method comprises the following steps:
Introducing the supplementary chlorosilane obtained by cold hydrogenation into a three-tower separation treatment, wherein the three-tower separation treatment can discharge light components in the supplementary chlorosilane from the top of the tower, medium components from the side of the tower, heavy components from the bottom of the tower, and extracting supplementary TCS from the side of the three-tower separation treatment;
and introducing the supplemented TCS and the recovered TCS into a separation second tower for carbon removal treatment.
Preferably, the method for controlling the content of carbon impurities in the disilicon for the reduction process further comprises the following steps:
extracting a third recovered DCS from the top of the separation three tower;
in the step S30, the first recovery DCS and/or the second recovery DCS are/is subjected to carbon removal by adsorption with a special adsorbent to obtain a raw material DCS after carbon removal, which comprises the steps of:
and adsorbing the first recovered DCS and/or the second recovered DCS and/or the third recovered DCS by a special adsorbent to remove carbon, thereby obtaining a raw material DCS after carbon removal.
Preferably, in the method for controlling the content of carbon impurities in disilane for a reduction process, in the step S10, the step of introducing the recovered chlorosilane into a separation-first column for separation treatment includes the steps of:
and introducing the supplementary chlorosilane obtained by cold hydrogenation and the recovered chlorosilane into the separation tower for separation treatment, and extracting mixed supplementary TCS and recovered TCS from the tower side of the separation tower.
Preferably, in the method for controlling the content of carbon impurities in disilicon for reduction process, the step S10 further includes the following steps:
separating and recovering the reduction tail gas to obtain recovered hydrogen, and adsorbing the supplementary hydrogen and the recovered hydrogen by a special adsorbent to remove carbon to obtain raw material hydrogen after carbon removal;
the step S40 includes the steps of:
the raw material DCS, the raw material hydrogen and the raw material TCS are mixed according to a proportion to be used as raw materials for a reduction process, and the raw materials enter a reduction furnace to carry out reduction reaction to prepare the polysilicon.
Preferably, in the method for controlling the carbon impurity content in the disilicon for the reduction process, the carbon impurity content in the raw material DCS is less than 1ppm, and the carbon impurity content in the raw material TCS is less than 8ppm.
The utility model provides a carbon impurity content control system in two silicon for reduction process, includes reduction furnace, tail gas recovery system, separation first tower, separation second tower and first absorption decarbonization device, reduction furnace's reduction tail gas export with tail gas recovery system's import links to each other, tail gas recovery system's chlorosilane export with separation first tower's import links to each other, separation first tower's tower side export with separation second tower's import links to each other, separation second tower's import still is connected with and supplements the TCS pipeline, separation first tower's top of tower export with separation second tower's top of tower export all links to each other with first absorption decarbonization device's import, separation second tower's tower side export with first absorption decarbonization device's export all links to each other with the import of reduction furnace.
Preferably, in the above-mentioned control system for carbon impurity content in disilicon for reduction process, further comprising a third separation tower, wherein the inlet of the third separation tower is connected with a first cold hydrogenation product pipeline, the tower side outlet of the third separation tower is connected with the inlet of the second separation tower through the additional TCS pipeline, and the tower top outlet of the third separation tower is connected with the inlet of the first adsorption carbon removal device.
Preferably, in the system for controlling the carbon impurity content in the disilicon for the reduction process, the inlet of the first separation tower is also connected with a second cold hydrogenation product pipeline.
Preferably, in the system for controlling the content of carbon impurities in disilicon for reduction process, the system further comprises a second adsorption carbon removal device, wherein the hydrogen outlet of the tail gas recovery system is connected with the inlet of the second adsorption carbon removal device, and the outlet of the second adsorption carbon removal device is connected with the inlet of the reduction furnace.
The technical scheme that this application adopted can reach following beneficial effect:
in the method and the system for controlling the content of carbon impurities in the disilane for the reduction process, the first recovery DCS and the recovery TCS are obtained by separating the recovery chlorosilane through the first separation tower, and the first separation tower can perform preliminary carbon removal treatment on the recovery TCS while playing a role in separating and recovering the chlorosilane, so that the effect of dual purposes of one object is realized. And the recovered TCS and the supplemented TCS are deeply decarbonized through the separation two towers, so that the second recovered DCS and the raw material TCS are obtained, the purity of the raw material TCS is ensured, the carbon impurity content in the raw material TCS is ensured to be lower, the carbon impurity in the reducing process is prevented from being introduced into the raw material TCS, and the carbon impurity in the reducing tail gas is mainly introduced into the raw material TCS, under the condition that the carbon impurity is not introduced into the reducing process by the raw material TCS, the carbon impurity in the reducing tail gas is not introduced into the raw material TCS, the recovered DCS can be recycled as the two silicon for the reducing process, the carbon impurity is not introduced into the reducing process in the process, and the raw material TCS can not continuously introduce new carbon impurity, so that the carbon impurity is prevented from being circularly accumulated in the reducing process, the carbon impurity content in the reducing tail gas is lower, the influence on the purity of polysilicon is reduced, and the produced polysilicon is low in content and high in quality.
The method has the advantages that the carbon impurities in the recovered DCS are prevented from being increasingly removed by introducing carbon impurities into the reduction process by the raw material TCS, the recovered DCS is adsorbed and removed through the special adsorbent, the carbon impurities in the recovered DCS are further removed on the basis of no carbon impurity introduction increase in the recovered DCS, the purity of the raw material DCS is ensured, the carbon impurities in the raw material DCS are ensured to be lower, the recovered DCS is subjected to carbon removal treatment before entering the reduction furnace as the reduction process for the two silicon to carry out reduction reaction with the raw material TCS to prepare the polysilicon, namely the recovered DCS is subjected to carbon removal treatment before each recycling, even if the raw material TCS can introduce the carbon impurities into the reduction process, the carbon impurities accumulated in a recycling way can be removed from the reduction process through the carbon removal step of the recovered DCS, the carbon impurities can be prevented from being circularly accumulated in the reduction process, the recycling of the recovered DCS containing the carbon impurities can be prevented from being circularly utilized as the reduction process, the two silicon for the reduction process is circularly utilized, the carbon impurities are circularly accumulated in the reduction process, the recovered DCS is prevented from being free of carbon recycling, and the polysilicon is prevented from being influenced by the carbon impurities in the reduction process, and the polysilicon is high in purity, and the polysilicon is prevented from being produced.
Drawings
FIG. 1 is a schematic diagram of a system for controlling the content of carbon impurities in disilicide for reduction process disclosed in the embodiment of the present application, wherein B1 to B8 represent carbon impurity detection points;
fig. 2 is a schematic diagram of a system for controlling the content of carbon impurities in disilicon for a reduction process according to another embodiment of the present application.
Description of the drawings: the reduction furnace 100, the tail gas recovery system 200, the first separation tower 300, the second separation tower 400, the third separation tower 500, the first adsorption decarbonization device 600, the supplemental TCS pipeline 710, the first cold hydrogenation product pipeline 720, the second cold hydrogenation product pipeline 730, the second adsorption decarbonization device 740, and the feed mixer 800.
Detailed Description
In order that the present application may be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Preferred embodiments of this application are given in the examples. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," "top," "bottom," "top," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1 to 2, an embodiment of the present application discloses a method for controlling the content of carbon impurities in disilicon for a reduction process, comprising the following steps:
s10, separating and recycling the reduction tail gas to obtain recovered chlorosilane, introducing the recovered chlorosilane into a first separation tower 300 for separation treatment, wherein the first separation tower 300 can discharge light components in the recovered chlorosilane from the top of the tower, medium components are discharged from the side of the tower, heavy components are discharged from the bottom of the tower, and a first recovered DCS and a recovered TCS are respectively extracted from the top and the side of the tower of the first separation tower 300;
the reducing tail gas mainly comprises chlorosilane, hydrogen and hydrogen chloride, and various methods for separating and recovering the reducing tail gas are available, and the method is not limited in the application. The reduction tail gas can be separated and recovered to obtain recovered hydrogen chloride, recovered hydrogen and recovered chlorosilane. The recovered chlorosilane contains a large amount of TCS, the content of which can reach about 30 percent, and has a larger recovery value. The recovered chlorosilane is introduced into a separation column 300 for separation treatment, and since the recovered chlorosilane mainly comprises DCS, TCS and STC, DCS with a low boiling point in the recovered chlorosilane is discharged through the column top by the separation column 300, STC with a high boiling point in the recovered chlorosilane and heavy component carbon impurities (monomethyl trichloro) are discharged through the column bottom, TCS with a middle boiling point and light component carbon impurities (monomethyl dichloro) are discharged through the column side, the separation column 300 can discharge light components (DCS) in the recovered chlorosilane from the column top, medium components (TCS and light component carbon impurities) from the column side, and heavy components (STC and heavy component carbon impurities) from the column bottom.
The recovered TCS is recovered from the column side of the separation column 300, and the recovered TCS is mainly TCS and contains a small amount of DCS and monomethyl dichloride. In this step, the separation of DCS, TCS and STC in the recovered chlorosilane can be achieved by the separation of the first column 300, TCS can be separated from monomethyl trichloro, carbon impurities (monomethyl trichloro) in the recovered TCS can be reduced, DCS, TCS and STC in the recovered chlorosilane can be separated and recovered, and preliminary decarbonization treatment (removal of monomethyl trichloro in the recovered TCS) can be performed on the recovered TCS, thereby achieving the effect of one product for two purposes. Since the recovered TCS contains a small amount of monomethyl dichloro, indicating that the recovered TCS also contains carbon impurities, further carbon removal is required based on the initial carbon removal.
S20, introducing the supplementary TCS and the recovered TCS into a second separation tower 400 for decarbonizing treatment, wherein the second separation tower 400 can discharge light components in the supplementary TCS and the recovered TCS from the top of the tower, medium components from the side of the tower, heavy components from the bottom of the tower, and respectively extracting second recovered DCS and raw material TCS from the top and the side of the tower of the second separation tower 400;
the amount of recovered TCS recovered and separated by the reduction tail gas is small, and the TCS required in the raw material for the reduction process cannot be satisfied, so that additional TCS is required, the additional TCS is called as additional TCS, and the additional TCS can be outsourced high-purity TCS. Since the recovered TCS still contains carbon impurities (monomethyl dichloro), further decarbonization is required, and in order to avoid the high carbon impurity content of the raw material TCS caused by the presence of carbon impurities in the supplemental TCS, both the supplemental TCS and the recovered TCS are introduced into the separation two column 400 to undergo decarbonization treatment, so as to ensure the low carbon impurity content in the raw material TCS and prevent the occurrence of accidental events (high carbon impurity content in the supplemental TCS) which result in the high carbon impurity content in the raw material TCS. Therefore, the supplemented TCS and the recovered TCS are both introduced into the separation second tower 400 for carbon removal treatment, so that the purity of the raw material TCS is ensured, and the content of carbon impurities in the raw material TCS is ensured to be lower.
Since monomethyl dichloro has a higher boiling point than TCS, monomethyl dichloro is a heavy component carbon impurity than TCS, so that the lower boiling DCS in make-up TCS and recovered TCS are discharged through the top of the column by separating the second column 400, the higher boiling monomethyl dichloro in make-up TCS and recovered TCS are discharged through the bottom of the column, and the intermediate boiling TCS are discharged through the side of the column, whereby separating the second column 400 enables the light component (DCS) in make-up TCS and recovered TCS to be discharged from the top of the column, the medium component (TCS) to be discharged from the side of the column, and the heavy component (monomethyl dichloro) to be discharged from the bottom of the column. The raw material TCS having a high purity is extracted from the column side of the separation two column 400. In this step, the separation of the additional TCS and the recovery of DCS, TCS and monomethyl dichloride in the TCS is achieved by the separation of the second column 400, and the additional TCS and the recovery of TCS are further decarbonized to ensure the purity of the raw TCS, and to ensure a lower carbon impurity content in the raw TCS, thereby reducing the introduction of carbon impurities during the reduction process.
S30, adsorbing the first recovered DCS and/or the second recovered DCS by a special adsorbent to remove carbon, so as to obtain a raw material DCS after carbon removal;
the first recovery DCS is extracted from the top of the first separation column 300 and/or the second recovery DCS is extracted from the top of the second separation column 400, and further decarbonized by adsorption with special adsorbents (such as decarbonizing resin, chelating resin, etc.), thereby ensuring the purity of the raw DCS and ensuring the low carbon impurity content in the raw DCS. Meanwhile, in the reduction process, DCS in the raw material is basically not consumed, and DCS is generated along with the occurrence of side reaction in the reduction reaction process, so that the total amount of the first recovered DCS and the second recovered DCS obtained by recovering the reduction tail gas can meet the requirement of disilicon in the raw material for the reduction process, and additional supplement of DCS is not needed.
S40, mixing the raw material DCS and the raw material TCS in proportion as raw materials for a reduction process, entering a reduction furnace 100 for reduction reaction to prepare polysilicon, recycling the DCS and the TCS in the reduction tail gas, and specifically, mixing the DCS and the TCS through a feed mixer 800, and then introducing the mixed materials into the reduction furnace 100.
In the method for controlling the content of carbon impurities in the disilane for the reduction process disclosed by the embodiment of the application, the first recovery DCS and the recovery TCS are obtained by separating the recovery chlorosilane through the first separation tower 300, and the first separation tower 300 can perform preliminary carbon removal treatment on the recovery TCS while playing a role in separating and recovering the chlorosilane, so that the effect of dual purposes of one object is realized. And the recovered TCS and the supplemented TCS are deeply decarbonized through the separation two towers 400 to obtain a second recovered DCS and a raw material TCS, the purity of the raw material TCS is ensured, the carbon impurity content in the raw material TCS is ensured to be lower, the carbon impurity in the reducing tail gas is prevented from being introduced into the reducing process, and because the carbon impurity in the reducing tail gas is mainly introduced from the raw material TCS, under the condition that the carbon impurity is not introduced into the reducing process by the raw material TCS, the carbon impurity in the recovered DCS is not introduced into the reducing tail gas, the recovered DCS can be recycled as the disilicon for the reducing process, the carbon impurity is not introduced into the reducing process in the process of repeatedly recovering the recovered DCS and recycling the disilicon for the reducing process, and the raw material TCS is not continuously introduced with new carbon impurity, so that the carbon impurity is prevented from being circularly accumulated in the reducing tail gas, the carbon impurity content in the reducing tail gas is lower, the influence on the purity of polysilicon is reduced, and the produced polysilicon is low in content and high in quality.
The method has the advantages that the carbon impurities in the recovered DCS are prevented from being increasingly removed by introducing carbon impurities into the reduction process by the raw material TCS, the recovered DCS is adsorbed and removed through the special adsorbent, the carbon impurities in the recovered DCS are further removed on the basis of no carbon impurity introduction increase in the recovered DCS, the purity of the raw material DCS is ensured, the carbon impurities in the raw material DCS are ensured to be lower, the recovered DCS is subjected to carbon removal treatment before entering the reduction furnace as the reduction process for the two silicon to carry out reduction reaction with the raw material TCS to prepare the polysilicon, namely the recovered DCS is subjected to carbon removal treatment before each recycling, even if the raw material TCS can introduce the carbon impurities into the reduction process, the carbon impurities accumulated in a recycling way can be removed from the reduction process through the carbon removal step of the recovered DCS, the carbon impurities can be prevented from being circularly accumulated in the reduction process, the recycling of the recovered DCS containing the carbon impurities can be prevented from being circularly utilized as the reduction process, the two silicon for the reduction process is circularly utilized, the carbon impurities are circularly accumulated in the reduction process, the recovered DCS is prevented from being free of carbon recycling, and the polysilicon is prevented from being influenced by the carbon impurities in the reduction process, and the polysilicon is high in purity, and the polysilicon is prevented from being produced.
As described above, the supplemental TCS may be outsourced high purity TCS, which is expensive, resulting in a high cost of polysilicon production. Optionally, in step S20, the make-up TCS and the recovered TCS are passed to the separation second column 400 for decarbonizing treatment, comprising the steps of:
introducing the supplementary chlorosilane obtained by cold hydrogenation into a three-column 500 for separation treatment, wherein the three-column 500 can discharge light components in the supplementary chlorosilane from the top of the column, medium components from the side of the column, heavy components from the bottom of the column, and the supplementary TCS is extracted from the side of the three-column 500;
the supplemental TCS and the recovered TCS are passed to a second separation column 400 for decarbonizing.
Specifically, the cold hydrogenation process converts STC recovered in the production process of polycrystalline silicon (for example, STC obtained by separating the STC in the step S10 by the first separation column 300) into TCS, obtains supplementary chlorosilane containing a large amount of TCS by the cold hydrogenation process, separates the supplementary chlorosilane by the third separation column 500 to obtain supplementary TCS therein, and similarly, the third separation column 500 can separate DCS, TCS and STC in the supplementary chlorosilane, and also separate TCS from monomethyl trichloro, reduce carbon impurities (monomethyl trichloro) in the supplementary TCS, and perform preliminary carbon removal treatment (removal of monomethyl trichloro in the supplementary TCS) on the supplementary TCS while playing a role in separating DCS, TCS and STC in the supplementary chlorosilane, thereby realizing a dual-purpose effect. The production cost is reduced by converting the STC recovered in the production process of the polysilicon into the complementary TCS, and the carbon removal treatment is further performed by the separation two tower 400, so that the purity of the raw material TCS is ensured, the carbon impurity content in the raw material TCS is ensured to be lower, and the introduction of the carbon impurity in the reduction process is reduced.
Of course, DCS can also be taken from the top of the separation three column 500, specifically S20 further comprises the steps of:
a third recovered DCS is withdrawn from the top of the separation three column 500;
in the step S30, adsorbing the first recovered DCS and/or the second recovered DCS by a special adsorbent to remove carbon to obtain a raw material DCS after carbon removal, wherein the method comprises the following steps of:
and adsorbing the first recovered DCS and/or the second recovered DCS and/or the third recovered DCS by a special adsorbent to remove carbon, thereby obtaining the raw material DCS after carbon removal. Realize the recovery of DCS in the supplementary chlorosilane and avoid waste.
The second recovery DCS taken out from the top of the separation second tower 400 is preferably introduced into the reduction furnace 100 in proportion because the second recovery DCS taken out from the top of the separation second tower 400 has a higher purity than the separation first tower 300 and the separation third tower 500, has a better quality than the second recovery DCS, can avoid the introduction of impurities, and has an advantage of low price compared to the outsourced high purity DCS.
Further, in step S10, the recovered chlorosilane is introduced into the separation-column 300 for separation treatment, comprising the steps of:
the supplemental chlorosilane obtained by cold hydrogenation and the recovered chlorosilane are fed together to the separation column 300 to be separated, and the mixed supplemental TCS and recovered TCS are extracted from the column side of the separation column 300.
Through directly introducing supplementary chlorosilane into the separation tower 300, separate and preliminary decarbonize together with retrieving chlorosilane, separation tower 300 not only can separate and preliminary decarbonize to retrieving chlorosilane, can also separate and preliminary decarbonize to retrieving chlorosilane, realizes the effect of a thing is multi-purpose, simultaneously, avoids adding extra separation tower and separates supplementary chlorosilane, reduces polycrystalline silicon production construction investment and cost.
Preferably, the content of carbon impurities in the raw material DCS is less than 1ppm, the content of carbon impurities in the raw material TCS is less than 8ppm, the content of carbon impurities in the raw material TCS is further ensured to be lower by limiting the content of carbon impurities in the raw material TCS to be less than 8ppm, the introduction of carbon impurities is further avoided, the content of carbon impurities in the raw material DCS is further ensured to be lower by limiting the content of carbon impurities in the raw material DCS to be less than 1ppm, the introduction of carbon impurities into a reduction process is avoided, and meanwhile, the recycling DCS containing the carbon impurities is further prevented from being recycled as disilicide for the reduction process to cause the recycling accumulation of the carbon impurities in the reduction process, so that the recycling DCS is free from carbon recycling.
Preferably, S10 further comprises the steps of:
separating and recovering the reduction tail gas to obtain recovered hydrogen, and adsorbing the supplementary hydrogen and the recovered hydrogen by a special adsorbent to remove carbon to obtain raw material hydrogen after carbon removal;
S40 comprises the steps of:
raw material DCS, raw material hydrogen and raw material TCS are mixed according to a proportion and used as raw materials for a reduction process to enter a reduction furnace 100 for reduction reaction to prepare polysilicon.
The recovery hydrogen obtained by separation in the reduction tail gas is subjected to carbon removal and is recovered for polysilicon production, carbon impurities in raw material hydrogen can be reduced while hydrogen recovery is realized, and the problem that the recovery hydrogen is similar to the recovery DCS in the recovery cyclic utilization process is avoided, so that the recovery hydrogen containing carbon impurities is used as hydrogen for the reduction process to be recycled, and the carbon impurities are accumulated in the reduction process in a cyclic manner, so that the recovery hydrogen is free from carbon cyclic utilization, the purity of polysilicon is prevented from being influenced due to more carbon impurities in the hydrogen for the original process, and the produced polysilicon has low carbon impurity content and high quality.
Meanwhile, hydrogen is taken as a raw material to participate in the reaction in the reduction reaction process, and residual hydrogen after the reaction is less, and hydrogen is generated along with the occurrence of side reaction in the reduction reaction process, but in general, the amount of recovered hydrogen obtained by recovering the reduction tail gas is less, and the hydrogen in the raw material for the reduction process cannot be satisfied. Therefore, additional hydrogen is needed, the additional hydrogen is called as additional hydrogen, and the additional hydrogen is generally outsourced high-purity hydrogen, basically has no carbon impurity or has a small content, so the additional hydrogen can be subjected to carbon removal through special adsorbents (such as carbon removal resin, ethanol-containing adsorbent and the like, which are the known technology, and the application is not limited), or can be subjected to carbon removal through adsorption without special adsorbents, and preferably, the additional hydrogen is subjected to carbon removal through adsorption with special adsorbents so as to ensure that the carbon impurity content in the raw material hydrogen is low, and the occurrence of accidental events (such as higher carbon impurity content in the additional hydrogen) is prevented so that the carbon impurity content in the raw material hydrogen is higher, and both the additional hydrogen and the recovered hydrogen are subjected to carbon removal through adsorption with special adsorbents so as to ensure the purity of the raw material hydrogen and ensure the lower carbon impurity content in the raw material hydrogen.
According to the scheme, the reduction tail gas is separated and recycled into hydrogen, DCS and TCS through a tail gas recycling system, the hydrogen, the DCS and the TCS are respectively decarbonized, and the carbon removing principle and the process are different. In the original design, the tail gas recovery system does not separate hydrogen and chlorosilane, and directly removes carbon as a mixture, and carbon components are different, so that the carbon removal effect is poor. Meanwhile, the DCS is not decarbonized in the original design, and the DCS is directly introduced into the anti-disproportionation device to be anti-disproportionated with the STC, so that the carbon content in the DCS is not controlled.
The hydrogen and DCS are adsorbed by special adsorbents, and the special adsorbent for removing carbon for hydrogen and the special adsorbent for removing carbon for DCS are not confused, and are different adsorbents, and although the adsorbents may be resin materials, the filled adsorbents are different, and the structure, pore diameter and the like are also different.
Referring to fig. 1 to 2 again, the embodiment of the present application further discloses a system for controlling the content of carbon impurities in disilicon for reduction process, which includes a reduction furnace 100, an exhaust gas recovery system 200, a first separation tower 300, a second separation tower 400, and a first adsorption carbon removal device 600, wherein:
the reducing tail gas outlet of the reducing furnace 100 is connected with the inlet of the tail gas recovery system 200 so as to introduce the reducing tail gas into the tail gas recovery system 200 for separation and recovery, the recovered hydrogen chloride, the recovered hydrogen and the recovered chlorosilane can be obtained after the separation and recovery of the reducing tail gas, the chlorosilane outlet of the tail gas recovery system 200 is connected with the inlet of the first separation tower 300, the recovered chlorosilane is introduced into the first separation tower 300 for separation treatment, the tower side outlet of the first separation tower 300 is connected with the inlet of the second separation tower 400, the recovered TCS is obtained from the tower side outlet of the first separation tower 300 so as to introduce the recovered TCS into the second separation tower 400 for carbon removal, the inlet of the second separation tower 400 is also connected with a complementary TCS pipeline 710, and meanwhile, the complementary TCS is also introduced into the second separation tower 400 for carbon removal, and the raw material TCS with higher purity is obtained from the tower side outlet of the second separation tower 400.
The top outlet of the first separation tower 300 and the top outlet of the second separation tower 400 are connected with the inlet of the first adsorption carbon removing device 600, a first recovery DCS is obtained from the top outlet of the first separation tower 300, a second recovery DCS is obtained from the top outlet of the second separation tower 400, the first recovery DCS and the second recovery DCS are introduced into the first adsorption carbon removing device 600, carbon is removed through adsorption by a special adsorbent, and a raw material DCS after carbon removal is obtained from the outlet of the adsorption carbon removing device 600.
The column side outlet of the separation two column 400 and the outlet of the first adsorption carbon removing apparatus 600 are both connected to the inlet of the reduction furnace 100. Raw materials DCS and TCS are taken as raw materials for a reduction process and enter a reduction furnace 100 for reduction reaction to prepare polycrystalline silicon, so that recycling of DCS and TCS in reduction tail gas is realized, and the DCS and TCS can be mixed through a feed mixer 800 and then introduced into the reduction furnace 100.
Preferably, the tower side outlet of the separation two tower 400 and the outlet of the first adsorption decarbonizing device 600 are both connected with the inlet of the feed mixer 800, and the outlet of the feed mixer 800 is connected with the inlet of the reduction furnace 100, so that the raw material TCS and the raw material DCS are firstly introduced into the feed mixer 800 for mixing, and then introduced into the reduction furnace 100 for reduction reaction after being uniformly mixed to prepare polysilicon, and the uniformly mixed raw material TCS and raw material DCS are uniformly and stably reacted in the reduction furnace 100, thereby being beneficial to the stability of the reduction reaction.
In the system for controlling the content of carbon impurities in the two silicon for the reduction process disclosed by the embodiment of the application, the recovered chlorosilane is subjected to separation treatment through the separation tower 300, then the raw material TCS is subjected to deep carbon removal through the separation tower 400, so that the raw material TCS is prevented from introducing carbon impurities into the reduction process, meanwhile, on the basis of increasing the introduction of carbon impurities in the recovered DCS, the carbon impurities in the recovered DCS are removed through the first adsorption carbon removal device 600, the purity of the raw material DCS is ensured, and the carbon impurities accumulated in a circulating way can be removed from the reduction process through the step of removing the carbon in the recovered DCS, so that the recovered DCS is free of carbon recycling, the purity of polysilicon is prevented from being influenced due to the fact that the carbon impurities in the two silicon for the original process are more, and the produced polysilicon is low in carbon impurity content and high in quality.
As described above, the supplemental TCS may be outsourced high purity TCS, which is expensive, resulting in a high cost of polysilicon production. Optionally, the system for controlling the carbon impurity content in the disilicon for the reduction process disclosed in the application may further include a third separation tower 500, wherein an inlet of the third separation tower 500 is connected with a first cold hydrogenation product pipe 720, a tower side outlet of the third separation tower 500 is connected with an inlet of the second separation tower 400 through a supplementary TCS pipe 710, the cold hydrogenation process converts STC (for example, STC obtained by separating the step S10 by the first separation tower 300) recovered in the polysilicon production process into TCS, a supplementary chlorosilane containing a large amount of TCS is obtained by the cold hydrogenation process, the supplementary chlorosilane is introduced into the third separation tower 500 through the first cold hydrogenation product pipe 720 to be separated, the supplementary TCS therein is obtained, and then the supplementary TCS is introduced into the second separation tower 400 through the supplementary TCS pipe 710 to be subjected to carbon removal treatment. Similarly, the separation tri-column 500 can separate DCS, TCS and STC from the supplementary chlorosilane, can separate TCS from monomethyl trichloro, reduce carbon impurities (monomethyl trichloro) in the supplementary TCS, and can perform preliminary decarbonization treatment (removal of monomethyl trichloro in the supplementary TCS) on the supplementary TCS while separating DCS, TCS and STC from the supplementary chlorosilane, thereby achieving a dual-purpose effect. The production cost is reduced by converting the STC recovered in the production process of the polysilicon into the complementary TCS, and the carbon removal treatment is further performed by the separation two tower 400, so that the purity of the raw material TCS is ensured, the carbon impurity content in the raw material TCS is ensured to be lower, and the introduction of the carbon impurity in the reduction process is reduced.
Of course, DCS can also be extracted from the top of the three separation column 500, specifically, the top outlet of the three separation column 500 is connected to the inlet of the first adsorption decarbonization device 600 to introduce the third recovered DCS extracted from the top of the three separation column 500 into the first adsorption decarbonization device 600 for decarbonization, to obtain decarbonized raw DCS. Realize the recovery of DCS in the supplementary chlorosilane and avoid waste.
The second recovery DCS taken out from the top of the separation second tower 400 is preferably introduced into the reduction furnace 100 in proportion because the second recovery DCS taken out from the top of the separation second tower 400 has a higher purity than the separation first tower 300 and the separation third tower 500, has a better quality than the second recovery DCS, can avoid the introduction of impurities, and has an advantage of low price compared to the outsourced high purity DCS.
Further, the inlet of the first separation tower 300 is further connected with a second cold hydrogenation product pipe 730, so that the supplementary chlorosilane obtained in the cold hydrogenation process is introduced into the first separation tower 300 through the second cold hydrogenation product pipe 730, the supplementary chlorosilane is directly introduced into the first separation tower 300, and is separated and primarily decarbonized together with the recovered chlorosilane, the first separation tower 300 not only can separate and primarily decarbonize the recovered chlorosilane, but also can separate and primarily decarbonize the recovered chlorosilane, thereby realizing the effect of one object with multiple purposes, simultaneously avoiding the need of adding an additional separation tower to separate the supplementary chlorosilane, and reducing the production and construction investment and cost of the polysilicon.
Preferably, the system for controlling the content of carbon impurities in the disilicon for the reduction process disclosed herein may further include a second adsorption carbon removing device 740, wherein the hydrogen outlet of the tail gas recovery system 200 is connected to the inlet of the second adsorption carbon removing device 740, and the outlet of the second adsorption carbon removing device 740 is connected to the inlet of the reduction furnace 100. The recovered hydrogen obtained by separation in the reduction tail gas is introduced into the second adsorption decarbonizing device 740 for decarbonizing and is recycled for polysilicon production, carbon impurities in raw material hydrogen can be reduced while hydrogen recovery is realized, the problem similar to that of recovered DCS in the process of recycling the recovered hydrogen is avoided, and thus the recovered hydrogen containing carbon impurities is avoided to be recycled as hydrogen for a reduction process, so that the carbon impurities are accumulated in the reduction process in a circulating way, the recovered hydrogen is recycled without carbon, the purity of polysilicon is prevented from being influenced due to more carbon impurities in the hydrogen for the original process, and the produced polysilicon has low carbon impurity content and high quality.
Embodiment one:
referring to fig. 1, according to the system for controlling the content of carbon impurities in the two silicon for the reduction process shown in fig. 1, and by applying the method for controlling the content of carbon impurities in the two silicon for the reduction process disclosed in the application, a furnace reducing furnace 100 is started (the production parameter of the reducing furnace 100 is 40 pairs of rods, the yield is 5 tons), the parameters in the production process of the polycrystalline silicon are matched according to the requirement of the reducing furnace 100, and after the reaction in the reducing furnace 100 is stable, i.e. the materials in the whole polycrystalline silicon production process reach dynamic balance, carbon impurities are detected according to the positions of B1 to B8 in fig. 1, the interval is 5 hours, and the measurement is performed three times, so that the carbon impurities in the polycrystalline silicon of the final product are also detected.
The results are shown in the following Table (in ppm).
According to the table, along with the recycling of DCS and repeated circulation for a plurality of times, the content of carbon impurities detected at each detection position tends to be stable in three times of detection, the situation of gradual increase does not occur, the variation range is smaller and does not exceed 10%, and the fact that the carbon impurities do not accumulate in the reduction process in a circulating way is indicated to be more and more. According to the principle, the content of the carbon impurities detected at each detection position is supposed to be reduced along with the increase of the cycle times, but the data tend to be stable, because DCS carbon removal and TCS carbon removal cannot be completely removed, and the content of the carbon impurities in each detection data is smaller, the content of the carbon impurities tends to be stable, so that the reduction process is not introduced with the carbon impurities, the carbon impurities in the raw materials are ensured to meet the process requirements while the carbon impurities are prevented from being introduced into the reduction process, and the DCS realizes the carbon-free accumulated cyclic utilization.
Meanwhile, the prior art is used for preparing polysilicon by taking recovered DCS as two silicon for a reduction process to enter a reduction furnace to carry out reduction reaction with TCS (TCS normally supplied in the prior art), the same raw materials are adopted in the initial stage of the reduction process, the reaction in the reduction furnace 100 is stable, namely, after the materials reach dynamic balance in the whole polysilicon production process, the content of carbon impurities in the recovered DCS and the produced polysilicon is detected, the interval is 5 hours, and the results are measured for three times, and are shown in the following table (unit is ppm).
According to the table, in the prior art, along with the recycling of DCS, and along with repeated recycling, the content of carbon impurities in the recycled DCS is greatly increased, and the carbon impurities are accumulated in a recycling way in a reduction process and are more and more, the content of the carbon impurities in the obtained polycrystalline silicon is as high as 8.2ppm, and the content of the carbon impurities in the polycrystalline silicon obtained by the method is only 3.9ppm, so that the reduction amplitude can reach 52.1%, and the DCS is free of carbon recycling in the method.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.
Claims (10)
1. The method for controlling the content of carbon impurities in the disilicon for the reduction process is characterized by comprising the following steps of:
s10, separating and recycling the reduction tail gas to obtain recovered chlorosilane, introducing the recovered chlorosilane into a separation tower (300) for separation treatment, wherein the separation tower (300) can discharge light components in the recovered chlorosilane from the top of the tower, medium components are discharged from the side of the tower, heavy components are discharged from the bottom of the tower, and first recovered DCS and recovered TCS are respectively extracted from the top and the side of the tower of the separation tower (300);
s20, introducing the supplementary TCS and the recovered TCS into a separation two-tower (400) for carbon removal treatment, wherein the separation two-tower (400) can discharge light components in the supplementary TCS and the recovered TCS from the top of the tower, medium components are discharged from the side of the tower, heavy components are discharged from the bottom of the tower, and a second recovered DCS and a raw material TCS are respectively extracted from the top and the side of the tower of the separation two-tower (400);
s30, adsorbing the first recovery DCS and/or the second recovery DCS by a special adsorbent to remove carbon, so as to obtain a raw material DCS after carbon removal;
s40, mixing the raw material DCS and the raw material TCS in proportion to serve as raw materials for a reduction process, and enabling the raw materials to enter a reduction furnace (100) for reduction reaction to prepare the polycrystalline silicon.
2. The method for controlling the carbon impurity content in disilicon for reduction process according to claim 1, wherein in the step S20, the additional TCS and the recovered TCS are introduced into a separation two column (400) to perform a decarbonization treatment, comprising the steps of:
introducing the supplementary chlorosilane obtained by cold hydrogenation into a three-separation tower (500) for separation treatment, wherein the three-separation tower (500) can discharge light components in the supplementary chlorosilane from the top of the tower, medium components from the side of the tower, heavy components from the bottom of the tower, and the supplementary TCS is extracted from the side of the three-separation tower (500);
and introducing the supplemented TCS and the recovered TCS into a separation two-tower (400) for carbon removal treatment.
3. The method for controlling the content of carbon impurities in disilicon for a reduction process according to claim 2, further comprising the steps of:
withdrawing a third recovered DCS from the top of the separation three column (500);
in the step S30, the first recovery DCS and/or the second recovery DCS are/is subjected to carbon removal by adsorption with a special adsorbent to obtain a raw material DCS after carbon removal, which comprises the steps of:
and adsorbing the first recovered DCS and/or the second recovered DCS and/or the third recovered DCS by a special adsorbent to remove carbon, thereby obtaining a raw material DCS after carbon removal.
4. The method for controlling the carbon impurity content in disilicon for reduction process according to claim 1, wherein in the step S10, the recovered chlorosilane is introduced into a separation column (300) for separation treatment, comprising the steps of:
and introducing the complementary chlorosilane obtained by cold hydrogenation and the recovered chlorosilane into the first separation tower (300) together for separation treatment, and extracting the complementary TCS and the recovered TCS in a mixed state from the tower side of the first separation tower (300).
5. The method for controlling the carbon impurity content in disilicon for reduction process according to claim 1, wherein the step S10 further comprises the steps of:
separating and recovering the reduction tail gas to obtain recovered hydrogen, and adsorbing the supplementary hydrogen and the recovered hydrogen by a special adsorbent to remove carbon to obtain raw material hydrogen after carbon removal;
the step S40 includes the steps of:
the raw material DCS, the raw material hydrogen and the raw material TCS are mixed according to a proportion and used as raw materials for a reduction process to enter a reduction furnace (100) for reduction reaction to prepare the polysilicon.
6. The method for controlling the carbon impurity content in disilicon for reduction process according to claim 1, wherein the carbon impurity content in the raw material DCS is less than 1ppm, and the carbon impurity content in the raw material TCS is less than 8ppm.
7. The utility model provides a carbon impurity content control system in two silicon for reduction process, its characterized in that includes reduction furnace (100), tail gas recovery system (200), separation first tower (300), separation second tower (400) and first adsorption carbon removal device (600), reduction furnace (100) reduce tail gas export with the import of tail gas recovery system (200) links to each other, the chlorosilane export of tail gas recovery system (200) with the import of separation first tower (300), the tower side export of separation first tower (300) with the import of separation second tower (400) links to each other, the import of separation second tower (400) still is connected with supplementary TCS pipeline (710), the top of a tower export of separation first tower (300) with the top of a tower export of separation second tower (400) all links to each other with the import of first adsorption carbon removal device (600), the tower side export of separation second tower (400) with the export of first adsorption carbon removal device (600) all links to each other with the import of reduction furnace (100).
8. The system for controlling the content of carbon impurities in disilicon for a reduction process according to claim 7, further comprising a three-separation column (500), wherein the inlet of the three-separation column (500) is connected with a first cold hydrogenation product pipe (720), the column-side outlet of the three-separation column (500) is connected with the inlet of the two-separation column (400) through the supplemental TCS pipe (710), and the column-top outlet of the three-separation column (500) is connected with the inlet of the first adsorption carbon removing device (600).
9. The system for controlling the carbon impurity content in disilicon for reduction process according to claim 7, wherein the inlet of the first separation tower (300) is further connected with a second cold hydrogenation product pipe (730).
10. The system for controlling the content of carbon impurities in disilicon for a reduction process according to claim 7, further comprising a second adsorption and carbon removal device (740), wherein the hydrogen outlet of the tail gas recovery system (200) is connected to the inlet of the second adsorption and carbon removal device (740), and the outlet of the second adsorption and carbon removal device (740) is connected to the inlet of the reduction furnace (100).
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| CN111232986A (en) * | 2018-11-29 | 2020-06-05 | 新特能源股份有限公司 | Tail gas recovery method and recovery system in polycrystalline silicon reduction production |
| CN110143595A (en) * | 2019-06-04 | 2019-08-20 | 新疆大全新能源股份有限公司 | The recovery process of tail gas is restored in a kind of production of polysilicon |
| CN110639328A (en) * | 2019-09-16 | 2020-01-03 | 新疆大全新能源股份有限公司 | Method for removing trace carbon impurities in tail gas recovery hydrogen treatment process |
| CN212315554U (en) * | 2020-02-24 | 2021-01-08 | 洛阳中硅高科技有限公司 | Device for removing carbon-containing impurities in high-purity chlorosilane production |
| CN212864156U (en) * | 2020-08-20 | 2021-04-02 | 新疆协鑫新能源材料科技有限公司 | Impurity removing device for polycrystalline silicon reduction tail gas |
| CN115838175A (en) * | 2022-11-02 | 2023-03-24 | 新特能源股份有限公司 | Method and system for removing carbon impurities in chlorosilane |
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