CN219860591U - High-purity two silicon recovery circulation system in polycrystalline silicon production process - Google Patents
High-purity two silicon recovery circulation system in polycrystalline silicon production process Download PDFInfo
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- CN219860591U CN219860591U CN202321377139.9U CN202321377139U CN219860591U CN 219860591 U CN219860591 U CN 219860591U CN 202321377139 U CN202321377139 U CN 202321377139U CN 219860591 U CN219860591 U CN 219860591U
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- 229910021420 polycrystalline silicon Inorganic materials 0.000 title claims abstract description 50
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 40
- 238000011084 recovery Methods 0.000 title claims description 20
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims description 5
- 229910052710 silicon Inorganic materials 0.000 title claims description 5
- 239000010703 silicon Substances 0.000 title claims description 5
- 238000000926 separation method Methods 0.000 claims abstract description 57
- 229920005591 polysilicon Polymers 0.000 claims abstract description 39
- 238000004064 recycling Methods 0.000 claims abstract description 35
- 230000009467 reduction Effects 0.000 claims abstract description 33
- 239000005046 Chlorosilane Substances 0.000 claims abstract description 28
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical compound Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000001257 hydrogen Substances 0.000 claims description 48
- 229910052739 hydrogen Inorganic materials 0.000 claims description 48
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 46
- 239000007789 gas Substances 0.000 claims description 33
- 238000003860 storage Methods 0.000 claims description 29
- 230000008676 import Effects 0.000 claims description 12
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 238000003786 synthesis reaction Methods 0.000 claims description 7
- 238000001179 sorption measurement Methods 0.000 claims description 4
- 230000000153 supplemental effect Effects 0.000 claims 1
- 239000012535 impurity Substances 0.000 abstract description 50
- 238000011946 reduction process Methods 0.000 abstract description 29
- 239000002994 raw material Substances 0.000 abstract description 21
- 238000000034 method Methods 0.000 abstract description 12
- 230000008569 process Effects 0.000 abstract description 10
- 230000001502 supplementing effect Effects 0.000 abstract description 7
- MROCJMGDEKINLD-UHFFFAOYSA-N dichlorosilane Chemical compound Cl[SiH2]Cl MROCJMGDEKINLD-UHFFFAOYSA-N 0.000 description 97
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 74
- 239000005052 trichlorosilane Substances 0.000 description 74
- 238000006722 reduction reaction Methods 0.000 description 30
- 239000008246 gaseous mixture Substances 0.000 description 29
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 12
- 229910052799 carbon Inorganic materials 0.000 description 12
- 238000005984 hydrogenation reaction Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- 238000000605 extraction Methods 0.000 description 7
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 6
- 229910052796 boron Inorganic materials 0.000 description 6
- 229910052698 phosphorus Inorganic materials 0.000 description 6
- 239000011574 phosphorus Substances 0.000 description 6
- 238000009835 boiling Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 238000007323 disproportionation reaction Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- NTQGILPNLZZOJH-UHFFFAOYSA-N disilicon Chemical compound [Si]#[Si] NTQGILPNLZZOJH-UHFFFAOYSA-N 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000012946 outsourcing Methods 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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Abstract
The utility model relates to a high-purity disilicide recycling system in a polysilicon production process, wherein a chlorosilane outlet of a tail gas recycling system is connected with an inlet of a separation tower, the inlet of the separation tower is provided with a first flowmeter, a tower top outlet of the separation tower is provided with a first flowmeter, a tower side outlet of the separation tower is provided with a second flowmeter, a tower side outlet of the separation tower and a supplementing TCS pipeline are both connected with an inlet of a mixer, and the supplementing TCS pipeline is provided with a second flowmeter. The DCS in the reduction tail gas replaces the DCS purchased from the outside in the prior art, the purchase cost and the transportation cost can be reduced without the purchase of the DCS, the production cost of the polysilicon can be reduced, the problems of poor safety and easy safety accidents in the transportation process due to the purchase of the DCS are avoided, the content can be accurately controlled, the impurity content in the raw materials for the reduction process is low, and the produced polysilicon is low in impurity content and high in quality.
Description
Technical Field
The utility model relates to the technical field of polysilicon production, in particular to a high-purity disilicide recycling system in the polysilicon production process.
Background
In the production of polysilicon, adding a proper amount of Dichlorosilane (DCS) into Trichlorosilane (TCS) used in a reducing furnace is beneficial to inhibiting the progress of side reaction and improving the deposition rate of polysilicon in the reducing furnace. The TCS used in the reduction furnace needs to control the DCS content, which is usually controlled between 1% and 5%. Along with the continuous improvement of the deposition rate and the product quality requirements of various enterprises in the reduction process, the DCS content in the TCS for reduction needs to be accurately controlled.
The method for controlling the DCS content in the TCS in the current industry mainly comprises the following steps: since the purity of DCS greatly affects the quality (impurity content) of polysilicon, most polysilicon manufacturers add outsourced DCS (which is due to the high purity of outsourced DCS) to synthesized TCS after rectification and purification (synthesized TCS obtained by rectifying and purifying hydrochlorosilane generated in the cold hydrogenation process) in proportion, and directly control the content of DCS in TCS by directly controlling the addition amounts of both TCS and DCS. However, the outsourced DCS is expensive, the purchase cost is high, the production cost of the polysilicon is high, and because the DCS is active, the outsourced DCS has poor safety in the transportation process and is easy to have safety accidents, the outsourced DCS needs stricter and comprehensive transportation safety guarantee measures and equipment, the transportation cost of the DCS is increased, the purchase cost of the DCS is further increased, and the production cost of the polysilicon is higher.
Disclosure of Invention
Based on this, it is necessary to add outsourced DCS to the synthesized TCS in proportion to the prior art for most polysilicon manufacturers to increase the deposition rate, but outsourced dichlorosilane is expensive and has high transportation cost, resulting in high purchase cost of dichlorosilane and thus high production cost of polysilicon. The utility model provides a high-purity two silicon recovery circulation system in polycrystalline silicon production process, DCS in the reduction tail gas replaces the DCS who outsources among the prior art, need not outsourcing DCS, can reduce purchase cost and transportation cost, be favorable to reducing polycrystalline silicon manufacturing cost, but also avoid having the problem of security poor, easy emergence incident in the transportation because of needs outsourcing DCS, and can accurate control content, can also make impurity content low in the raw materials for the reduction process, avoid introducing impurity, and then can make the polycrystalline silicon impurity content of production low, the quality is high.
The utility model provides a high-purity two silicon recovery circulation system in polycrystalline silicon production process, includes reducing furnace, tail gas recovery system, knockout tower, supplementary TCS pipeline, controlling means and blender, reducing 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 the import of knockout tower links to each other, just the import of knockout tower is provided with first flowmeter, the top of the tower export of knockout tower is provided with first flowmeter, the tower side export of knockout tower with the import of blender links to each other, just the tower side export of knockout tower is provided with the second flowmeter, supplementary TCS pipeline with the import of blender links to each other, just supplementary TCS pipeline is provided with the second flowmeter, first flowmeter, second flowmeter and second flowmeter all with controlling means electricity is connected, the export of blender with the import of reducing furnace links to each other.
Preferably, in the high-purity disilicide recycling system in the polysilicon production process, the recycling system further comprises a gaseous synthesis TCS storage tank, wherein an outlet of the gaseous synthesis TCS storage tank is connected with an inlet of the mixer through the supplementary TCS pipeline.
Preferably, in the high-purity disilicide recycling system in the production process of polysilicon, a fourth flowmeter is arranged at the bottom outlet of the separation tower, and the fourth flowmeter is electrically connected with the control device.
Preferably, in the recycling system for high-purity disilicide in the production process of polysilicon, the recycling system further comprises a hydrogen storage tank, wherein the outlet of the mixer is provided with a third flowmeter, the outlet of the hydrogen storage tank and the outlet of the mixer are both connected with the inlet of the reduction furnace, the outlet of the hydrogen storage tank is provided with a third flowmeter, and the third flowmeter are both electrically connected with the control device.
Preferably, in the high-purity disilicide recycling system in the production process of polysilicon, a hydrogen outlet of the tail gas recycling system is connected with an inlet of the hydrogen storage tank.
Preferably, in the high-purity disilicon recycling system in the polysilicon production process, an adsorption decarbonizing device is arranged at the inlet or the outlet of the hydrogen storage tank.
Preferably, in the high-purity disilicide recycling system in the production process of polysilicon, the inlet of the hydrogen storage tank is also connected with a hydrogen supplementing pipeline.
Preferably, in the high-purity disilicide recycling system in the production process of polysilicon, the system further comprises a DCS storage tank, and an outlet at the top of the separation tower is connected with the DCS storage tank.
The technical scheme adopted by the utility model can achieve the following beneficial effects:
in the recycling system for high-purity disilicide in the production process of the polysilicon disclosed by the embodiment of the utility model, (1) the carbon impurities and the phosphorus impurities of heavy components in the recovered chlorosilane are discharged through the bottom of the separation tower, and the boron impurities of light components are discharged through the top of the separation tower, so that the gaseous mixture A extracted from the side of the separation tower basically does not contain the carbon impurities, the phosphorus impurities and the boron impurities, the impurity content is low, the purity is high, and the gaseous mixture A is introduced into a reduction furnace for recycling in the subsequent process, so that the impurity content in raw materials for the reduction process is low, the introduction of impurities is avoided, and the produced polysilicon is low in impurity content and high in quality. (2) The DCS in the reduction tail gas replaces the DCS purchased from the outside in the prior art, the DCS purchased from the outside is not needed, the purchase cost and the transportation cost can be reduced, the production cost of the polysilicon can be reduced, and the problems that the safety is poor and the safety accident occurs easily in the transportation process because the DCS purchased from the outside is needed can be avoided. (3) The control of the DCS content ratio in the raw materials for the reduction process is realized by adjusting the size of V2 to control the specific value of B%, and the stability of B% is high by adjusting the size of V2, so that the control precision is high, and the stable and accurate control of the DCS molar ratio in the gaseous mixture C plays a very large role in the stable operation of the reduction furnace 100. (4) Compared with the mode of mixing high-purity DCS and TCS in proportion in the prior art, the TCS contains a small amount of DCS, the existence of the DCS can interfere with a calculation result, the actual proportion of the high-purity DCS and the TCS obtained by recovering the reduction tail gas after being mixed in proportion is different from the theoretical proportion, and a certain amount of DCS is reserved in the extracted TCS directly, so that the proportion of the final material is accurately controlled, and the stability of the reduction process is prevented from being influenced. (5) In the prior art, the chlorosilane obtained by the hydrogenation process is separated to obtain DCS, and the DCS is used for being mixed with TCS to be used as a raw material for the reduction process, compared with the DCS which is obtained by recycling the reduction tail gas and is used as the raw material for the reduction process, the purity of the gaseous mixture A obtained by recycling the reduction tail gas is higher than that of the TCS obtained by the hydrogenation process and the impurity content is lower than that of the TCS obtained by the hydrogenation process, therefore, compared with the DCS which is used as the raw material for the reduction process and is used in the reduction tail gas, the impurity content in the raw material for the reduction process is lower, the introduction of impurities is avoided, and the produced polycrystalline silicon has low impurity content and high quality.
Drawings
Fig. 1 is a schematic diagram of a recycling system of high purity disilicon in a polysilicon production process according to an embodiment of the present utility model, wherein a dotted line represents an electrical connection line.
Description of the drawings: a reduction furnace 100, an exhaust gas recovery system 200, a separation tower 300, a gaseous synthesis TCS storage tank 400, a control device 500, a hydrogen storage tank 600, a mixer 700 and a DCS storage tank 800.
Detailed Description
In order that the utility model may be readily understood, a more particular description of the utility model will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Preferred embodiments of the present utility model are shown in the examples. This utility model may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth 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 utility model belongs. The terminology used herein in the description of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. 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, an embodiment of the utility model discloses a recycling system for high purity disilicide in a polysilicon production process, which comprises a reduction furnace 100, an exhaust gas recycling system 200, a separation tower 300, a supplementing TCS pipeline, a control device 500 and a mixer 700, wherein:
the reducing exhaust outlet of the reducing furnace 100 is connected to the inlet of the exhaust recovery system 200 to introduce the reducing exhaust into the exhaust recovery system 200 for separation, and the reducing exhaust mainly includes chlorosilane, hydrogen and hydrogen chloride, and there are various methods for separating and recovering the reducing exhaust, which are not limited in the present utility model. 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 chlorosilane outlet of the tail gas recovery system 200 is connected with the inlet of the separation tower 300, and the recovered chlorosilane is introduced into the separation tower 300 for separation treatment, because the recovered chlorosilane mainly comprises DCS, TCS and STC, the DCS with low boiling point in the recovered chlorosilane is discharged from the tower top through the separation tower 300, the STC with high boiling point in the recovered chlorosilane and heavy component carbon impurities are discharged from the tower bottom, the TCS with middle boiling point and a small amount of DCS are discharged from the tower side, and therefore, the separation tower 300 can discharge the light component (DCS) in the recovered chlorosilane from the tower top, the middle component (TCS and a small amount of DCS) is discharged from the tower side, and the heavy component (STC and heavy component carbon impurities) is discharged from the tower bottom. And the inlet of the separation tower 300 is provided with a first flowmeter, and the flow velocity V1 of the recovered chlorosilane flowing into the separation tower 300 is detected, and the cross-sectional area of the pipeline of the recovered chlorosilane flowing into the separation tower 300 is S1, which indicates that the flow rate of the recovered chlorosilane flowing into the separation tower 300 is V1S 1, and in the polycrystalline silicon production process, the mass ratio of DCS, TCS and STC in the reducing tail gas is basically stable, so that the mass ratio of DCS, TCS and STC in the gaseous recovered chlorosilane obtained by separating and recovering the reducing tail gas is basically stable, and therefore, the flow rate of DCS flowing into the separation tower 300 is V1S 1 a% and the mass ratio of DCS in the recovered chlorosilane is a%. Typically, the chlorosilane recovery is about 3% DCS, 30% TCS, and 66% STC, in which case A% is 3%.
Since the chlorosilane is recovered to contain the heavy component carbon impurities and the phosphorus impurities and the light component boron impurities, the heavy component carbon impurities and the phosphorus impurities are discharged from the bottom of the separation tower 300, and the light component boron impurities are discharged from the top of the separation tower 300, so that the materials extracted from the side of the separation tower 300 are basically free of the impurities, and the materials extracted from the side of the separation tower 300 are required to be introduced into the reduction furnace 100 for recycling, the recycled materials have higher purity, the introduction of impurities is avoided, and the influence of the impurities on the purity of the produced polysilicon is reduced, so that the produced polysilicon has low impurity content and high quality. Therefore, the separation tower 300 can separate and recycle DCS, TCS and STC in the chlorosilane, and simultaneously remove impurities from materials extracted from the side of the separation tower 300, so that the purity of the recycled materials is high, and the effect of one-object dual-purpose is realized.
The first flow valve is disposed at the top outlet of the separation column 300, the opening of the first flow valve is controlled, and the gaseous recovery DCS is extracted from the top of the separation column 300 at the flow rate V2, and the cross-sectional area of the extraction pipe for recovering DCS from the top of the separation column 300 is S2, which means that the flow rate of recovery DCS extracted from the top of the separation column 300 is V2 x S2, and at this time, the residual DCS in the separation column 300 is extracted through the column side of the separation column 300, and at the same time, TCS is also extracted through the column side of the separation column 300, so the material extracted from the column side of the separation column 300 is the gaseous mixture a of DCS and TCS. The outlet on the tower side of the separation tower 300 is connected to the inlet of the mixer 700, and the outlet on the tower side of the separation tower 300 is provided with a second flow rate meter, and the second flow rate meter detects that the extracted flow rate of the gaseous mixture a is V3, and the cross-sectional area of the extracted pipe is S3, which means that the flow rate of the gaseous mixture a extracted from the tower side of the separation tower 300 is V3S 3, and since the remaining DCS is extracted through the tower side of the separation tower 300, the flow rate of the extracted DCS is V1S 1 a% -V2S 2 in the extracted gaseous mixture a.
The additional TCS pipe is connected to the inlet of the mixer 700, and since the amount of TCS recovered and separated by the reduction tail gas is small, it is not enough to meet the requirement of TCS in the raw material for the reduction process, and thus additional TCS is required, and the additional TCS may be outsourced high purity TCS, which is not limited in the present utility model. The supplemented TCS is supplemented into the raw material for the reduction process through a supplementing TCS pipeline so as to meet the requirement of TCS in the raw material for the reduction process.
The supplementary TCS pipe is provided with a second flow rate valve, and the first flow rate meter, the first flow rate valve, the second flow rate meter, and the second flow rate valve are all electrically connected with the control device 500, and the outlet of the mixer 700 is connected with the inlet of the reduction furnace 100. By controlling the opening of the second flow valve, the additional TCS obtained by hydrogenation and rectification is mixed with the gaseous mixture a according to the flow velocity V4 to obtain the gaseous mixture C, that is, the additional TCS at the flow velocity V4 is mixed with the gaseous mixture a at the flow velocity V3 to obtain the gaseous mixture C, the cross-sectional area of the additional TCS additional conduit is S4, which means that the flow rate of the additional TCS additional is V4S 4, the amount (volume) of the gaseous mixture C is v3+v4S 4 in unit time, the gaseous mixture a contains DCS in the form of v1×s1% -v2×s2, so that the gaseous mixture C also contains DCS in the form of v1×s1% -v2×s2, the molar ratio of DCS in the gaseous mixture C is b%, the molar ratio of DCS in the form of (((v1×s1% -v2×s2)/(M1)/(M1×v3)/(S2) is S2) in the molar ratio of DCS in the gaseous mixture C is 1×v2), and the molar ratio of DCS in the gaseous mixture C is equal to the molar ratio of DCS in the mass of cs 2 is equal to M2, and the molar ratio of DCS in the gaseous mixture is equal to M2. And finally, introducing the gaseous mixture C serving as a raw material for a reduction process into a reduction furnace 100 for reduction reaction to prepare the polycrystalline silicon. The calculation control process is completed by the control device 500.
The specific value of B% is controlled by adjusting the size of V2, that is, the amount of DCS in the gaseous mixture A extracted from the tower side of the separation tower 300 is controlled by controlling the amount of DCS extracted from the tower top of the separation tower 300, so that the molar ratio of DCS in the finally obtained gaseous mixture C meets the process requirement. Meanwhile, the content of substances is basically kept stable in the whole process, and the stability of B% is high by adjusting the size of V2, so that the control precision is high, and the stable and accurate control of the molar ratio of DCS in the gaseous mixture C plays a very great role in the stable operation of the reduction furnace 100.
In the recycling system for high-purity disilicide in the production process of polysilicon disclosed by the embodiment of the utility model, (1) the carbon impurities and the phosphorus impurities of heavy components in the recovered chlorosilane are discharged through the bottom of the separation tower 300, and the boron impurities of light components are discharged through the top of the separation tower, so that the gaseous mixture A extracted from the side of the separation tower 300 basically does not contain the carbon impurities, the phosphorus impurities and the boron impurities, the impurity content is low, the purity is high, and the gaseous mixture A is introduced into the reduction furnace 100 for recycling in the subsequent process, thereby the impurity content in the raw materials for the reduction process is low, the introduction of the impurities is avoided, and the produced polysilicon is low in impurity content and high in quality. (2) The DCS in the reduction tail gas replaces the DCS purchased from the outside in the prior art, the DCS purchased from the outside is not needed, the purchase cost and the transportation cost can be reduced, the production cost of the polysilicon can be reduced, and the problems that the safety is poor and the safety accident occurs easily in the transportation process because the DCS purchased from the outside is needed can be avoided. (3) The control of the DCS content ratio in the raw materials for the reduction process is realized by adjusting the size of V2 to control the specific value of B%, and the stability of B% is high by adjusting the size of V2, so that the control precision is high, and the stable and accurate control of the DCS molar ratio in the gaseous mixture C plays a very large role in the stable operation of the reduction furnace 100. (4) Compared with the mode of mixing high-purity DCS and TCS in proportion in the prior art, the TCS contains a small amount of DCS, the existence of the DCS can interfere with a calculation result, the actual proportion of the high-purity DCS and the TCS obtained by recovering the reduction tail gas after being mixed in proportion is different from the theoretical proportion, and a certain amount of DCS is reserved in the extracted TCS directly, so that the proportion of the final material is accurately controlled, and the stability of the reduction process is prevented from being influenced. (5) In the prior art, the chlorosilane obtained by the hydrogenation process is separated to obtain DCS, and the DCS is used for being mixed with TCS to be used as a raw material for the reduction process, compared with the DCS which is obtained by recycling the reduction tail gas and is used as the raw material for the reduction process, the purity of the gaseous mixture A obtained by recycling the reduction tail gas is higher than that of the TCS obtained by the hydrogenation process and the impurity content is lower than that of the TCS obtained by the hydrogenation process, therefore, compared with the DCS which is used as the raw material for the reduction process and is used in the reduction tail gas, the impurity content in the raw material for the reduction process is lower, the introduction of impurities is avoided, and the produced polycrystalline silicon has low impurity content and high quality.
As described above, the additional TCS may be an outsourced high purity TCS, which may result in higher production costs due to the higher price of the outsourced high purity TCS, and based on this, optionally, a gaseous synthesis TCS tank 400 is further included, the outlet of the gaseous synthesis TCS tank 400 being connected to the inlet of the mixer 700 through an additional TCS pipe. The hydrogenation process converts STC recovered in the production process of polysilicon (such as STC extracted from the bottom of the separation tower 300) into TCS, the hydrogenation process obtains supplementary chlorosilane containing a large amount of TCS, the supplementary chlorosilane is purified by rectification to obtain gaseous synthetic TCS therein, the gaseous synthetic TCS is stored in the gaseous synthetic TCS storage tank 400, and the gaseous synthetic TCS is supplemented into the raw material for the reduction process through the supplementary TCS pipeline so as to meet the requirement of TCS in the raw material for the reduction process, thereby effectively reducing the production cost.
Preferably, a fourth flow rate meter is provided at the bottom outlet of the separation column 300, and the fourth flow rate meter is electrically connected to the control device 500. The recovered chlorosilane introduced into the separation column 300 is separated and then extracted through the column top, the column side and the column bottom, and since the recovered chlorosilane generally has about 3% DCS, 30% TCS and 66% STC, at least 66% STC is required to be extracted from the column bottom of the separation column 300, and therefore, at most 33% DCS and TCS are extracted from the column top and the column side of the separation column 300, in order to avoid the extraction of STC from the column side, the actual extraction amounts of the column side and the column top should be less than 33%, and by controlling the extraction amounts of the column side, the unnecessary extraction of STC is avoided, thereby being advantageous in improving the purity of the gaseous mixture C and preventing the presence of STC impurities. The amount of extraction from the bottom outlet of the separation column 300 was detected by the fourth flowmeter so as to exceed 66% and to avoid the influence of the purity by extraction of non-extracted STC from the column side.
The raw material for the reduction process should further include hydrogen, specifically, a hydrogen storage tank 600, wherein a third flow rate meter is disposed at an outlet of the mixer 700, the outlet of the hydrogen storage tank 600 and the outlet of the mixer 700 are both connected with an inlet of the reduction furnace 100, and the outlet of the hydrogen storage tank 600 is provided with a third flow rate valve, and the third flow rate meter and the third flow rate valve are both electrically connected with the control device 500. The third flow rate meter is matched with the control of the third flow rate valve, so that the hydrogen and the gaseous mixture C are mixed in proportion, automatic control is realized, and the control precision is high.
The hydrogen can be outsourced hydrogen, but the cost is higher, alternatively, the hydrogen outlet of the tail gas recovery system 200 is connected with the inlet of the hydrogen storage tank 600, and the hydrogen obtained by recovering the tail gas is introduced into the hydrogen storage tank 600 for recovering and recycling the hydrogen for the reduction process, so that the production cost can be reduced while the hydrogen is prevented from being wasted.
Because the content of carbon impurities in the hydrogen recovered through the tail gas is higher, optionally, an adsorption carbon removal device is arranged at the inlet or outlet of the hydrogen storage tank 600, and the recovered hydrogen is adsorbed and removed by a special adsorbent in the adsorption carbon removal device, so that the influence on the reduction process and the purity and quality of the produced polysilicon due to the high content of carbon impurities in the recovered hydrogen is avoided.
The hydrogen amount recovered by the tail gas is small, and the hydrogen requirement for the reduction process cannot be met, so that additional hydrogen is required, further, the inlet of the hydrogen storage tank 600 is also connected with a hydrogen supplementing pipeline, outsourced hydrogen is introduced into the hydrogen storage tank 600 through the hydrogen supplementing pipeline, and the outsourced hydrogen and the hydrogen recovered by the reduction tail gas are used together for the hydrogen requirement for the reduction process, so that the hydrogen requirement for the reduction process is met.
As described above, part of DCS is extracted from the top of the separation tower 300, and the extracted DCS can be introduced into the anti-disproportionation device to be anti-disproportionated with STC to generate TCS, so that the apparatus further comprises a DCS storage tank 800, the top outlet of the separation tower 300 is connected with the DCS storage tank 800, and DCS extracted from the top outlet of the separation tower 300 is introduced into the DCS storage tank 800 for use in the subsequent process, or the outlet of the DCS storage tank 800 is connected with the anti-disproportionation device, and DCS is introduced into the anti-disproportionation device to be anti-disproportionated with STC to generate TCS, thereby improving the recycling rate of useful resources and simultaneously avoiding serious environmental pollution caused by DCS emission.
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 illustrate only a few embodiments of the utility model, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the utility model, which are all within the scope of the utility model. Accordingly, the scope of protection of the present utility model is to be determined by the appended claims.
Claims (8)
1. The utility model provides a high-purity two silicon recovery circulation system in polycrystalline silicon production process, its characterized in that includes reduction furnace (100), tail gas recovery system (200), separator tower (300), supplementary TCS pipeline, controlling means (500) and blender (700), 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 separator tower (300) links to each other, just the import of separator tower (300) is provided with first flowmeter, the top of a tower export of separator tower (300) is provided with first flowmeter, the tower side export of separator tower (300) with the import of blender (700) links to each other, just the tower side export of separator tower (300) is provided with the second flowmeter, supplementary TCS pipeline with the import of blender (700) links to each other, just supplementary TCS pipeline is provided with the second flowmeter, first flowmeter, second flowmeter with the export of controller (300) is connected with the import of blender (700).
2. A high purity disilicide recycling system in a polysilicon production process according to claim 1, further comprising a gaseous synthesis TCS tank (400), an outlet of the gaseous synthesis TCS tank (400) being connected to an inlet of the mixer (700) through the supplemental TCS conduit.
3. The recycling system for high purity disilicide in polysilicon production process according to claim 1, wherein a fourth flowmeter is provided at a bottom outlet of the separation tower (300), and the fourth flowmeter is electrically connected with the control device (500).
4. The recycling system for high purity disilicide in the production process of polysilicon according to claim 1, further comprising a hydrogen storage tank (600), wherein a third flowmeter is provided at an outlet of the mixer (700), the outlet of the hydrogen storage tank (600) and the outlet of the mixer (700) are both connected to an inlet of the reduction furnace (100), and a third flowmeter valve is provided at an outlet of the hydrogen storage tank (600), and the third flowmeter valve are both electrically connected to the control device (500).
5. The recycling system for high purity disilicide in polysilicon manufacturing process according to claim 4, wherein the hydrogen outlet of said tail gas recycling system (200) is connected to the inlet of said hydrogen tank (600).
6. The recycling system for high purity disilicide in polysilicon manufacturing process according to claim 5, wherein an adsorption decarbonizing device is provided at an inlet or an outlet of the hydrogen tank (600).
7. The recycling system for high purity disilicide in polysilicon manufacturing process according to claim 5, wherein the inlet of said hydrogen tank (600) is further connected with a supplementary hydrogen pipe.
8. The recycling system for high purity disilicide in polysilicon production process according to claim 1, further comprising a DCS tank (800), wherein the top outlet of the separation column (300) is connected to the DCS tank (800).
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116654942A (en) * | 2023-05-31 | 2023-08-29 | 内蒙古润阳悦达新能源科技有限公司 | Method and system for measuring and controlling recovery of high-purity disilicon in polysilicon reduction raw material |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116654942A (en) * | 2023-05-31 | 2023-08-29 | 内蒙古润阳悦达新能源科技有限公司 | Method and system for measuring and controlling recovery of high-purity disilicon in polysilicon reduction raw material |
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