CN118543300A - Silane moving bed reaction system - Google Patents
Silane moving bed reaction system Download PDFInfo
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- CN118543300A CN118543300A CN202310188078.XA CN202310188078A CN118543300A CN 118543300 A CN118543300 A CN 118543300A CN 202310188078 A CN202310188078 A CN 202310188078A CN 118543300 A CN118543300 A CN 118543300A
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- reactor
- heater
- stripper
- silane
- gas
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- 238000006243 chemical reaction Methods 0.000 title claims abstract description 55
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 title claims abstract description 53
- 229910000077 silane Inorganic materials 0.000 title claims abstract description 53
- 239000007789 gas Substances 0.000 claims abstract description 83
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 41
- 229920005591 polysilicon Polymers 0.000 claims abstract description 35
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000012495 reaction gas Substances 0.000 claims abstract description 26
- 239000013078 crystal Substances 0.000 claims abstract description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 32
- 239000001257 hydrogen Substances 0.000 claims description 32
- 238000010438 heat treatment Methods 0.000 claims description 26
- 229910052710 silicon Inorganic materials 0.000 claims description 22
- 239000010703 silicon Substances 0.000 claims description 22
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 21
- 150000002431 hydrogen Chemical class 0.000 claims description 13
- 238000005485 electric heating Methods 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 229910010272 inorganic material Inorganic materials 0.000 claims description 5
- 150000002484 inorganic compounds Chemical class 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 239000001307 helium Substances 0.000 claims description 3
- 229910052734 helium Inorganic materials 0.000 claims description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 3
- 229910052743 krypton Inorganic materials 0.000 claims description 3
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052754 neon Inorganic materials 0.000 claims description 3
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000005192 partition Methods 0.000 claims description 3
- 229910052724 xenon Inorganic materials 0.000 claims description 3
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 3
- 239000011863 silicon-based powder Substances 0.000 abstract description 10
- 238000005979 thermal decomposition reaction Methods 0.000 abstract description 5
- 239000002245 particle Substances 0.000 description 16
- 238000000034 method Methods 0.000 description 11
- 238000000354 decomposition reaction Methods 0.000 description 8
- 239000011856 silicon-based particle Substances 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 6
- 230000001681 protective effect Effects 0.000 description 6
- 239000011819 refractory material Substances 0.000 description 5
- 238000004806 packaging method and process Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000007740 vapor deposition Methods 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- -1 silicon inorganic compound Chemical class 0.000 description 1
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 1
- 239000005052 trichlorosilane Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
- B01J8/087—Heating or cooling the reactor
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B28/00—Production of homogeneous polycrystalline material with defined structure
- C30B28/12—Production of homogeneous polycrystalline material with defined structure directly from the gas state
- C30B28/14—Production of homogeneous polycrystalline material with defined structure directly from the gas state by chemical reaction of reactive gases
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention relates to a silane moving bed reaction system, which comprises a heater, a reactor and a stripper, wherein polysilicon enters the heater to be heated to a reaction temperature, the heated polysilicon enters the reactor from top to bottom to generate crystal growth, reaction gas enters the reactor from bottom to top and reversely contacts and reacts with the polysilicon in the reactor, and tail gas after reaction is discharged from the upper part of the reactor; the polysilicon after reaction enters a stripper for stripping; the pressure in the heater is greater than the pressure in the reactor, the stripper pressure is greater than the reactor pressure, the lower part of the heater is provided with a shielding gas inlet, the upper part of the heater is provided with a shielding gas outlet, shielding gas enters the heater from the shielding gas inlet and is discharged from the shielding gas outlet, and the problem that silicon powder is formed by thermal decomposition of silane in the heater is solved by controlling the flow of the shielding gas to maintain the pressure difference between the heater and the reactor to be greater than or equal to 10 kPa.
Description
Technical Field
The disclosure relates to the technical field of polysilicon production, in particular to a silane moving bed reaction system.
Background
At present, the global production of polysilicon mostly adopts the modified Siemens method and the silane thermal decomposition method, and the silane thermal decomposition method is also divided into two forms of rod-shaped heating vapor deposition and fluidized bed vapor deposition.
The improved Siemens method is mainly characterized in that trichlorosilane is adopted to react with hydrogen to generate silicon and other byproducts, the generated silicon is deposited in a heating rod of a bell-type reactor, and the process technology is mature, but the reaction temperature is high, electric heating is adopted, and the comprehensive energy consumption is high. The main characteristic of the thermal decomposition method of silane is that it uses silane to decompose on the surface of silicon crystal to generate silicon and hydrogen, and the silane method has certain advantage in energy consumption due to simple purification of silane and low reaction temperature.
The problem with conventional silane rod-shaped heated vapor deposition is that the reaction take-out needs to be stopped when the silicon rod grows to a certain size, and continuous production cannot be realized. The problem of the silane fluidized bed vapor deposition is that on one hand, heat sources are needed to be provided for the endothermic reaction of the silane decomposition, and the heated part of the silane is subjected to homogeneous nucleation to form silicon powder, so that product waste is brought, and on the other hand, seed crystal particles are in a fluidized state in a reactor and constantly scour the walls, so that impurities are entrained, and the purity of the product is influenced.
However, the heating zone and the reaction zone in the related art are not completely separated, so that reacted silane flows from a channel where particles fall to the heating zone, and in fact, homogeneous decomposition of silane still occurs in the heating zone to generate silicon powder, and the generated silicon powder blocks a discharging channel, which is unfavorable for the reaction.
Disclosure of Invention
The purpose of the present disclosure is to provide a silane moving bed reaction system, which can solve the technical problems in the related art.
In order to achieve the above object, the present disclosure provides a silane moving bed reaction system including a heater, a reactor, and a stripper, and an outlet of the heater is in communication with an inlet of the reactor, and an outlet of the reactor is in communication with an inlet of the stripper; the polycrystalline silicon enters the heater to be heated to the reaction temperature, the heated polycrystalline silicon enters the reactor from top to bottom to generate crystal growth, and the reaction gas enters the reactor from bottom to top and reversely contacts and reacts with the polycrystalline silicon in the reactor, and the tail gas after the reaction is discharged from the upper part of the reactor; the polysilicon after reaction enters the stripper for stripping;
The pressure in the heater is greater than the pressure in the reactor, the pressure in the stripper is greater than the pressure in the reactor, the lower part of the heater is provided with a shielding gas inlet, the upper part of the heater is provided with a shielding gas outlet, shielding gas enters the heater from the shielding gas inlet and is discharged from the shielding gas outlet, and the flow rate of the shielding gas is controlled to maintain the pressure difference between the heater and the reactor to be greater than or equal to 10kPa.
Optionally, a hydrogen inlet is arranged at the upper part of the stripper, stripped hydrogen enters the stripper from the hydrogen inlet and is discharged from an outlet of the stripper, and the pressure difference between the stripper and the reactor is maintained to be more than or equal to 10kPa by controlling the flow rate of the stripped hydrogen.
Optionally, the heating mode of the heater is to heat the gas in the heater firstly and then to heat the polysilicon by using the gas, and the mode of heating the gas is one or a combination of a plurality of modes of direct microwave heating, electric heating rod heating and heat exchange tube partition wall heating.
Optionally, the reactor is configured as a conical structure, the reactor tapers from top to bottom, the inlet of the reactor is provided with a gas distributor, and the outlet of the reactor is provided with a filtering internal.
Optionally, the heater, the reactor and the inner wall of the stripper are all provided with silicon or an inorganic compound of silicon.
Optionally, the reaction gas is silane or a mixture of silane and hydrogen.
Optionally, the shielding gas is one or a mixture of several of helium, neon, argon, krypton, xenon, hydrogen and nitrogen.
Optionally, the reactor adopts a moving bed container with an upper elliptical seal head and a lower conical seal head, wherein the inner diameter of the upper part is between 1000mm and 2000mm, the inner diameter of the lower part is between 500mm and 1000mm, and the tangential length is between 3000mm and 5000 mm.
Optionally, the stripper adopts a container with an upper elliptic seal head and a lower conical seal head, wherein the inner diameter of the container is between 800mm and 1200mm, and the tangential length of the container is between 1000mm and 2000 mm.
Optionally, the stripper is made of a material lined with a silicon inorganic compound.
In the technical scheme, the protective gas is introduced into the heater, and the flow rate of the protective gas entering or exiting the heater is controlled by the pressure difference between the heater and the reactor, so that the pressure of the heater is ensured to be higher than that of the reactor. Therefore, in the falling process of the heated polysilicon, gas flows from the heater to the reactor, so that no silane is ensured in the heater, the problem that the silane of the heater is thermally decomposed to form silicon powder is thoroughly solved, and the silicon powder is prevented from blocking a discharging channel. And the pressure in the stripper 3 is higher than the pressure in the reactor 2, so that the gas can flow from bottom to top.
In addition, in the reactor, the solids gradually move downwards, the reaction gas is injected from the lower part and flows upwards through the solid bed layer in the reactor to react, and the tail gas after the reaction is discharged from the upper part of the reaction gas. As the silane decomposition is an endothermic reaction, heat is derived from sensible heat carried by the polysilicon, and the temperature of the polysilicon is reduced along with the growth of the polysilicon, so that the whole reactor presents a state of upper heat and lower cold, the upper temperature of the reactor reaches the highest temperature of the silane decomposition, and the lower temperature is lower than the lowest temperature of the silane decomposition. The reaction gas flows from bottom to top and gradually reacts, the concentration of the reaction gas at the lower part is high, and the concentration of the reaction gas gradually decreases along with the progress of the reaction and the generation of hydrogen at the upper part. Because of the countercurrent contact mode, the concentration of the reaction gas is low at the position with high temperature, the concentration of the reaction gas is high at the position with low temperature, the overall reaction rate is uniform, the gas phase temperature is lower than the temperature of polysilicon, the reaction is easy to occur on the surface of particles rather than in the gas phase, and the dust generation amount is further reduced.
Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:
FIG. 1 is a schematic block diagram of a silane moving bed reaction system according to one embodiment of the present disclosure.
Description of the reference numerals
1. Heater 2 reactor
3. Stripper 11 shielding gas inlet
12. The shielding gas outlet 4 is used for shielding gas
7. Reaction gas 8 tail gas
9. Stripping hydrogen 20 polysilicon
Detailed Description
Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.
Referring to fig. 1, the present disclosure provides a silane moving bed reaction system including a heater 1, a reactor 2, and a stripper 3, with an outlet of the heater 1 communicating with an inlet of the reactor 2, and an outlet of the reactor 2 communicating with an inlet of the stripper 3; the polysilicon 20 enters the heater 1 to be heated to the reaction temperature, the heated polysilicon 20 enters the reactor 2 from top to bottom to generate crystal growth, the reaction gas 7 enters the reactor 2 from bottom to top and reversely contacts with the polysilicon 20 in the reactor 2 to generate reaction, and the tail gas 8 after the reaction is discharged from the upper part of the reactor 2; the polysilicon 20 after the reaction enters a stripper 3 for stripping;
The pressure in the heater 1 is greater than the pressure in the reactor 2, the pressure in the stripper 3 is greater than the pressure in the reactor 2, the lower part of the heater 1 is provided with a shielding gas inlet 11, the upper part of the heater 1 is provided with a shielding gas outlet 12, shielding gas 4 enters the heater 1 from the shielding gas inlet 11 and is discharged from the shielding gas outlet 12, and the pressure difference between the heater 1 and the reactor 2 is maintained to be greater than or equal to 10kPa by controlling the flow rate of the shielding gas 4.
In the above technical scheme, the protective gas 4 is introduced into the heater 1, and the flow rate of the protective gas 4 entering or exiting the heater 1 is controlled by the pressure difference between the heater 1 and the reactor 2, so that the pressure of the heater 1 is ensured to be higher than the pressure of the reactor 2. In this way, in the falling process of the heated polysilicon 20, gas flows from the heater 1 to the reactor 2, so that no silane is ensured in the heater 1, the problem that silicon powder is formed by thermal decomposition of silane in the heater 21 is thoroughly solved, and the problem that the silicon powder can block a discharging channel is avoided. And the pressure in the stripper 3 is higher than the pressure in the reactor 2, so that the gas can flow from bottom to top. In the reactor 2, the solids gradually move downward, the reaction gas 7 is injected from the lower part, the reaction proceeds by flowing upward through the solid bed in the reactor 2, and the tail gas after the reaction is discharged from the upper part of the reaction gas 7. Since the silane decomposition is an endothermic reaction, heat is derived from sensible heat carried by the polysilicon 20, and as the polysilicon 20 grows in size, the polysilicon 20 temperature decreases, so that the entire reactor 2 presents an upper hot-to-lower cold state, the upper temperature of the reactor reaches the highest temperature of the silane decomposition, and the lower temperature is lower than the lowest temperature of the silane decomposition. Since the reaction gas 7 flows from bottom to top and gradually reacts, the concentration of the reaction gas 7 is high in the lower portion, and the concentration of the reaction gas 7 gradually decreases in the upper portion as the reaction proceeds and hydrogen gas is generated. Because of the countercurrent contact mode, the concentration of the reaction gas 7 at the position with high temperature is low, the concentration of the reaction gas 7 at the position with low temperature is high, the overall reaction rate is uniform, the gas phase temperature is lower than that of the polysilicon 20, the reaction is easy to occur on the surface of particles rather than in the gas phase, and the dust generation amount is further reduced.
Optionally, referring to fig. 1, the upper part of the stripper 3 is provided with a hydrogen inlet 31, and the stripped hydrogen 9 enters the stripper 3 from the hydrogen inlet 31 and is discharged from an outlet of the stripper 3, and the pressure difference between the stripper 3 and the reactor 2 is maintained to be 10kPa or more by controlling the flow rate of the stripped hydrogen 9.
In this embodiment, by injecting hydrogen 9 into stripper 3, the pressure in stripper 3 is maintained higher than the pressure in reactor 2, ensuring that the gas can flow from bottom to top.
In one embodiment, the heating mode of the heater 1 is to heat the gas in the heater 1 first and then to heat the polysilicon 20 by using the gas, and the heating mode of the gas is one or a combination of a plurality of modes of direct microwave heating, electric heating rod heating and partition wall heating of a heat exchange tube, which is not limited in the disclosure.
Alternatively, the reactor 2 is constructed in a conical structure, and the reactor 2 is tapered from top to bottom, the inlet of the reactor 2 is provided with a gas distributor, and the outlet of the reactor 2 is provided with a filtering internal. The present disclosure is not limited to the specific structural shape of the reactor 2.
In other embodiments, the heater 1, the reactor 2 and the inner wall of the stripper 3 are provided with silicon or an inorganic compound of silicon, which facilitates the reaction of the polysilicon 20.
Alternatively, the reaction gas 7 is silane or a mixture of silane and hydrogen, but the present disclosure is not limited to the specific type of the reaction gas 7.
The shielding gas 4 is one or a mixture of helium, neon, argon, krypton, xenon, hydrogen, and nitrogen, but the disclosure is not limited to the shielding gas 4.
In one embodiment, reactor 2 employs a moving bed vessel with an upper elliptical head and a lower conical head having an upper inner diameter of between 1000mm and 2000mm, a lower inner diameter of between 500 and 1000mm, and a tangential length of between 3000mm and 5000mm, although the specific shape and dimensions of reactor 2 are not limited by the present disclosure.
In other embodiments, the stripper 3 employs a vessel having an inner diameter of between 800mm and 1200mm, an upper elliptical head and a lower conical head with a tangential length of between 1000mm and 2000mm, although the specific shape and dimensions of the stripper 3 are not limited by the present disclosure.
Example 1: silane countercurrent moving bed reaction system heated by airflow
As shown in the attached drawing, the silane countercurrent moving bed reaction system heated by the airflow is specifically designed as follows:
the heater 1 adopts an upper elliptical seal head with an inner diameter of 1500mm and a tangent line length of 4000mm, and a container with a lower conical seal head. The cone angle of the conical end enclosure is 60 degrees, the nickel-based alloy shell is selected as the material of the heater 1, and the silicon-based refractory material is lined with a silicon plate. A jacket can be arranged outside the outer wall for cooling according to the heat conduction condition of the refractory material. The bottom of the cone angle connects the flange and the line to the reactor 2. After heating to 1000 ℃, the hot hydrogen enters the heater 1 through the shielding gas inlet 11 and leaves the heater 1 through the shielding gas outlet 12. In addition, regulating valves can be arranged on pipelines of the protective gas inlet 11 and the protective gas outlet 12, the temperature of hot hydrogen entering the heater 1 is controlled through the temperature of the polysilicon 20 falling to the reactor 2, the temperature is low by the increased temperature, and the temperature of the polysilicon 20 falling to the reactor 2 is ensured to be controlled at 1000 ℃; the heating of the hydrogen gas may be performed in a heating furnace or an electric heater. The control is to control the heating power of the electric heater, and the control is to control the fuel flow of the heating furnace.
The reactor 2 can adopt a moving bed container with an upper elliptical seal head and a lower conical seal head, wherein the inner diameter of the upper part is 2000mm, the inner diameter of the lower part is 1000mm, the tangential length is 5000mm, the cone angle of the conical seal head is 60 degrees, and the material is 316L lining silicon-based refractory material lining silicon plate. The gas inlet of the reactor 2 is provided with an annular distributor, so that the reaction gas can be uniformly distributed. The gas outlet of the reactor 2 is provided with a filter to avoid fines and seeds from being carried out of the reactor 2. The bottom of the cone angle connects the flange and the line to the stripper 3. The upper reaction temperature was 1000 ℃, and the silicon particles were discharged from the bottom at a temperature of about 500 ℃. The pressure in reactor 2 was 0.2MPag. The mixed gas containing 5% of silane and the rest of hydrogen is preheated to 500 ℃ and then enters from the bottom of the reactor 2, and the tail gas 8 is discharged from the upper part of the reactor 2.
The stripper 3 can adopt a container with an inner diameter of 1200mm, an upper elliptic seal head with a tangential line length of 2000mm and a lower conical seal head. The pressure of the stripper 3 is kept higher than that of the reactor 2 by injecting hydrogen into the stripper 3, the stripped hydrogen 9 enters from the upper part of the stripper 3, a regulating valve can be arranged at the upper part of the stripper 3, and the flow of the stripped hydrogen 9 is increased when the pressure difference is small and is controlled by the pressure difference between the stripper 3 and the reactor (2), so that the pressure difference is maintained at 10kPa. This control scheme ensures that the gas flows from bottom to top.
After the silicon particles at the outlet of the lower part of the stripper 3 are cooled, the silicon particles are primarily screened according to the thickness of 1mm and 1.5mm and are divided into three parts: less than 1mm,1mm-1.5 mm, greater than 1.5mm. A small part of the particles with the diameter smaller than 1mm are sent back to the seed crystal preparation device again, and the residual high purity silicon required by the seed crystal preparation unit is replenished by the particle size part with the diameter of 1mm to 1.5mm. The remaining silicon particles enter a post-treatment packaging unit. The seed preparation unit and the post-treatment packaging unit are not represented in the figures.
The size of the polysilicon 20 was 0.8mm in average equivalent diameter, the void fraction was 0.4, the particle retention time was 40h, and the average equivalent diameter at the time of particle discharge was 1.5mm. The residence time of the particles is controlled by the particle transport means at the outlet of the stripper 3. The polysilicon particles produced by the technology can reach the first-level standard of solar energy, and the silicon powder yield is only about one third of that of the fluidized bed method.
Example 2: silane countercurrent moving bed reaction system utilizing electric heating
As shown in figure 1 of the specification, the countercurrent moving bed reaction system of silane by electric heating is specifically as follows:
The heater 1 can adopt an upper elliptical seal head with an inner diameter of 2000mm and a tangential length of 5000mm, and a container with a lower conical seal head is internally inserted with an electric heating rod. The cone angle of the conical end enclosure is 60 degrees, and the material is 316L lining silicon-based refractory material lining silicon plate. The bottom of the cone angle connects the flange and the line to the reactor 2. The power of the electric heater is controlled through the temperature of the polysilicon 20 falling to the reactor 2, the power of the electric heater is increased due to the low temperature, and the temperature of the polysilicon 20 falling to the reactor 2 is controlled at 850 ℃; the hydrogen serving as the shielding gas 4 enters the shielding gas inlet 11 of the heater 1, a regulating valve is arranged at the shielding gas inlet 11, the flow of the shielding gas 4 is controlled by the pressure difference between the heater 1 and the reactor 2, the flow of the shielding gas 4 is increased by small pressure difference, and the pressure difference between the heater 1 and the reactor 2 is ensured to be 40kPa. Under this control scheme, the shielding gas is totally introduced into the reactor 2, ensuring that the gas flow is from the heater 1 to the reactor 2.
The reactor 2 adopts a moving bed container with an upper elliptical seal head and a lower conical seal head, wherein the inner diameter of the upper part is 3000mm, the inner diameter of the lower part is 2200mm, the tangential length is 7000mm, the cone angle of the conical seal head is 60 degrees, and the material is 316L lining silicon-based refractory material lining silicon plate. The bottom of the cone angle connects the flange and the line to the stripper 3. The upper reaction temperature was 800 ℃, and the silicon particles were discharged from the bottom at a temperature of about 600 ℃. The reactor 2 pressure was 0.7MPag. The reaction gas 7 silane is preheated to 500 ℃ and then enters from the bottom of the reactor 2, and the tail gas 8 is discharged from the upper part of the reactor 2. The gas inlet of the reactor 2 is provided with an annular distributor, so that the reaction gas can be uniformly distributed. The gas outlet of the reactor 2 is provided with a filter to avoid bringing fines and seeds out of the reactor.
The stripper 3 adopts a container with an inner diameter of 1200mm, an upper elliptical seal head and a lower conical seal head with a tangential line length of 2000 mm. The stripping hydrogen 9 enters from the upper part of the stripper 3, the upper part of the stripper 3 can be provided with a regulating valve, the flow of the stripping hydrogen 9 is increased when the pressure difference is small through the pressure difference control of the stripper 3 and the reactor 2, and the pressure difference is maintained at 50kPa. This control scheme ensures that the gas flows from bottom to top.
After the silicon particles at the outlet of the lower part of the stripper 3 are cooled, the silicon particles are primarily screened according to 1.4mm and 2mm and are divided into three parts: less than 1.4mm,1.4mm-2mm and more than 2mm. A small part of the particles with the diameter smaller than 1.4mm are sent back to the seed crystal preparation device again, and the residual high-purity silicon required by the seed crystal preparation unit is replenished by the particle size part with the diameter of 1.4mm-2 mm. The remaining silicon particles enter a post-treatment packaging unit. The seed preparation unit and the post-treatment packaging unit are not represented in the figures.
The polysilicon 20 has a size of 0.8-1mm in average equivalent diameter, a void fraction of 0.4, a particle residence time of 50 hours, and an average equivalent diameter of 2mm when the particles are discharged. The polysilicon particles produced by the technology can reach the solar primary standard, and the silicon powder yield is only about 24% of that of the fluidized bed method.
The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the embodiments described above, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.
In addition, the specific features described in the foregoing embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present disclosure does not further describe various possible combinations.
Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.
Claims (10)
1. A silane moving bed reaction system, which is characterized by comprising a heater, a reactor and a stripper, wherein an outlet of the heater is communicated with an inlet of the reactor, and an outlet of the reactor is communicated with an inlet of the stripper; the polycrystalline silicon enters the heater to be heated to the reaction temperature, the heated polycrystalline silicon enters the reactor from top to bottom to generate crystal growth, and the reaction gas enters the reactor from bottom to top and reversely contacts and reacts with the polycrystalline silicon in the reactor, and the tail gas after the reaction is discharged from the upper part of the reactor; the polysilicon after reaction enters the stripper for stripping;
the pressure within the heater is greater than the pressure within the reactor, and the pressure within the stripper is greater than the pressure within the reactor;
The lower part of the heater is provided with a shielding gas inlet, the upper part of the heater is provided with a shielding gas outlet, shielding gas enters the heater from the shielding gas inlet and is discharged from the shielding gas outlet, and the pressure difference between the heater and the reactor is maintained to be more than or equal to 10kPa by controlling the flow of the shielding gas.
2. A silane moving bed reaction system according to claim 1, wherein a hydrogen inlet is provided at an upper portion of the stripper, stripped hydrogen enters the stripper from the hydrogen inlet and is discharged from an outlet of the stripper, and a pressure difference between the stripper and the reactor is maintained to be 10kPa or more by controlling a flow rate of the stripped hydrogen.
3. The silane moving bed reaction system of claim 1, wherein the heater is heated by heating gas in the heater first and then heating polysilicon by using gas, and the heating gas is one or a combination of direct microwave heating, electric heating rod heating and heat exchange tube partition wall heating.
4. The silane moving bed reaction system according to claim 1, wherein the reactor is configured in a conical structure, the reactor tapers from top to bottom, a gas distributor is arranged at an inlet of the reactor, and a filtering internal is arranged at an outlet of the reactor.
5. A silane moving bed reaction system according to claim 1, characterized in that the heater, the reactor and the inner wall of the stripper are all provided with silicon or an inorganic compound of silicon.
6. A silane moving bed reaction system according to claim 1, wherein the reaction gas is silane or a mixture of silane and hydrogen.
7. The silane moving bed reaction system according to claim 2, wherein the shielding gas is one or a mixture of helium, neon, argon, krypton, xenon, hydrogen, and nitrogen.
8. The silane moving bed reaction system according to claim 1, wherein the reactor adopts a moving bed container with an upper inner diameter of 1000mm-2000mm, a lower inner diameter of 500mm-1000mm, an upper elliptical head with a tangential length of 3000mm-5000mm and a lower conical head.
9. The silane moving bed reaction system according to claim 1, wherein the stripper adopts a container with an upper elliptical head and a lower conical head, wherein the inner diameter of the container is 800mm-1200mm, and the tangential length of the container is 1000mm-2000 mm.
10. A silane moving bed reaction system according to claim 9, wherein the stripper is made of a silicon-lined inorganic compound material.
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| CN202310188078.XA CN118543300A (en) | 2023-02-24 | 2023-02-24 | Silane moving bed reaction system |
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