An energy-saving fluidized bed device for producing high-purity granular silicon
By installing a heat exchanger and auxiliary gas inlet in the fluidized bed reactor, combined with a gas distributor and multi-nozzle design, the silicon deposition problem was solved, enabling efficient utilization of heat and silicon powder in the non-deposition zone, reducing energy consumption, and improving production efficiency and equipment utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG QUHUA FLUOR CHEM CO LTD
- Filing Date
- 2025-07-07
- Publication Date
- 2026-07-03
AI Technical Summary
Fluidized bed reactors suffer from silicon deposition problems when producing granular silicon, which leads to impeded heat transfer, increased energy consumption, and reactor wear. Furthermore, heat in the non-deposition zone cannot be effectively utilized.
A heat exchanger and an auxiliary gas inlet are installed inside the reactor. The heat exchanger recovers heat from the non-deposition zone, and the auxiliary gas is used to blow fine silicon powder back to the reaction zone. Combined with a gas distributor and a multi-nozzle design, uniform gas distribution and silicon powder reuse are achieved.
It effectively reduces silicon deposition, lowers energy consumption, increases production capacity, enables efficient and continuous production of high-purity granular silicon, and reduces equipment investment.
Smart Images
Figure CN224442965U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of high-purity granular silicon production technology, specifically to an energy-saving sprayed fluidized bed device for producing high-purity granular silicon. Background Technology
[0002] Polycrystalline silicon is a core material in the photovoltaic and semiconductor fields. Its mainstream production methods include the modified Siemens process and the fluidized bed reactor (FBR). The former generates silicon rods through the hydrogen reduction of trichlorosilane, which is energy-intensive; the latter uses silane as a raw material to deposit granular silicon in a fluidized bed, allowing for continuous production with lower energy consumption. It is important to note that the fluidized bed process has a larger depositable surface area for seed crystals compared to the Siemens process when producing granular silicon. Therefore, the reaction and deposition efficiency of the fluidized bed process are significantly improved compared to the Siemens process, while energy consumption is relatively reduced. Furthermore, with increasing environmental and energy-saving requirements, the high energy consumption bottleneck of the traditional Siemens process has become prominent, making the production of granular silicon using the fluidized bed process a technological focus. Granular silicon can be directly used for subsequent processing of monocrystalline silicon without crushing, making it suitable for efficient production processes.
[0003] Patent CN102271797B incorporates a baffle (bubble splitter) in a fluidized bed reactor. Its internal channels allow heated fluid to pass through, transferring heat to the reaction zone and improving heat utilization. Cooling gas leaving the bubble splitter can be reheated and participate in the fluidization of the bed, reducing energy waste. However, this method inevitably introduces silica particles, which are not effectively recovered and cause significant damage to the reactor walls.
[0004] Patent CN215783248U uses an external heater to heat the fluidized bed reactor, and combines this with temperature information monitored by a temperature measuring rod to precisely control the heating process, avoiding overheating and achieving energy savings. However, silicon formed by the pyrolysis of silane gas inside the reactor often deposits on the inner wall of the reactor body, hindering heat transfer to the reactor interior. This can also prevent silane from reaching the pyrolysis temperature, reducing reaction efficiency and effective deposition on seed crystals, thus affecting production efficiency. This phenomenon is exacerbated, especially after the fluidized bed reactor is scaled up, leading to silicon deposition on the reactor inner wall, resulting in production shutdowns for maintenance and disruptions to normal operations.
[0005] To address the issue of silicon deposition on the reactor inner wall, patent CN102713001B discloses a novel fluidized bed reactor. By designing a special central inlet nozzle, it creates a vertical column of gas in the center of the reactor chamber, reducing silicon deposition on the nozzle and reactor wall. Patent CN105460938B discloses a reactor with a baffle element. By placing the baffle element in the reactor's freeboard area, it blocks rising particles from impacting the reactor wall and causing silicon powder deposition. Furthermore, the baffle element is made of non-contaminating material or coated with a protective layer, reducing product contamination. While both methods suppress silicon deposition within the reactor wall to some extent, they consume significant energy, and excess heat cannot be effectively utilized.
[0006] In summary, the problem of silicon deposition in fluidized bed reactors has remained largely unresolved during operation. Silicon deposition not only reduces the reactor's heat transfer efficiency, hindering heat transfer and failing to effectively meet reaction demands, but also causes wear and tear on the reactor's internal structure due to the fine silicon powder generated within the reactor, such as eroding the reactor walls and damaging internal components. Finally, the reactor contains a densely packed seed deposition zone at the bottom and a non-deposition zone at the top. The non-deposition zone has a heat surplus that cannot be effectively utilized, significantly increasing energy consumption and imposing a substantial economic burden on production. Utility Model Content
[0007] To address the aforementioned technical problems and shortcomings in the field, this utility model provides an energy-saving jet fluidized bed device for producing high-purity granular silicon, which can effectively utilize the temperature of the non-deposition zone, reduce silicon deposition, and achieve large-scale, efficient, and continuous production of high-purity granular silicon.
[0008] The specific technical solution is as follows:
[0009] An energy-saving spouted fluidized bed device for producing high-purity granular silicon, comprising a reactor;
[0010] The middle section of the reactor is the reaction zone. A seed inlet is set on the side of the reactor corresponding to the reaction zone. A gas distributor is set below the reaction zone in the reactor. The gas distributor is connected to the raw material gas inlet pipe and the product discharge device. Gas inlet 1 and auxiliary carrier gas inlet are set below the gas distributor in the reactor.
[0011] A heat exchanger is installed above the reaction zone inside the reactor. The heat exchanger has a flow channel and is connected to a cold gas inlet pipe and a gas outlet pipe. The gas outlet pipe is connected to an auxiliary carrier gas inlet.
[0012] The reactor is equipped with an auxiliary gas inlet, which is used at least for ventilation to blow fine powders (such as fine silicon powder) that have passed upward through the heat exchanger back to the reactor's reaction zone, facilitating the reuse of these powders. The auxiliary gas inlet can be supplied with nitrogen or similar gases.
[0013] In the aforementioned energy-saving fluidized bed reactor for producing high-purity granular silicon, hydrogen enters the reactor through the gas inlet, and nitrogen enters the reactor through the auxiliary carrier gas inlet. The hydrogen and nitrogen entering the reactor are introduced into the reaction zone through the gas distributor. Raw material gas, such as trichlorosilane, enters the reaction zone through the raw material gas inlet pipe. Granular silicon seed crystals enter the reaction zone through the seed inlet. The granular silicon seed crystals are kept suspended under the combined blowing of the raw material gas, hydrogen, and nitrogen. In the reaction zone, hydrogen reduces the raw material gas, and the generated elemental silicon is deposited on the granular silicon seed crystals. As the reaction proceeds, the granular silicon particles continue to grow. After reaching the process set size, they fall to the product discharge device due to gravity. The product discharge device can be filled with inert gas to prevent the high-temperature product from being oxidized. After the reaction zone has been reacting for a period of time, the temperature of the non-deposition zone above the reaction zone in the reactor rises. At this time, cooling gas, such as nitrogen, can enter the heat exchanger through the cold gas inlet pipe to absorb the heat from the non-deposition zone. Then, it enters the auxiliary carrier gas inlet through the gas outlet pipe and then enters the reaction zone through the gas distributor, thus achieving the purpose of heat recovery and utilization.
[0014] This invention effectively collects fine silicon powder within the reactor into the deposition zone (reaction zone) for reuse by incorporating a heat exchanger within the reactor and using an auxiliary gas inlet. The auxiliary gas inlet can be located above the heat exchanger. For better backflushing of silicon powder particles, preferably, the auxiliary gas inlet extends through a pipeline above the flow channel of the heat exchanger. Further, the pipeline can be divided into multiple branches, each corresponding to a flow channel of the heat exchanger. More preferably, each branch is equipped with a gas flow regulating valve to control the airflow of its corresponding branch; when no airflow is required, the airflow is zero.
[0015] The gas distributor plays a crucial role in ensuring the uniform distribution of gas within the reaction zone and the normal progress of the reaction. This device can evenly distribute the gas entering from the feed gas inlet pipe into the reaction zone, preventing localized excessively high or low gas concentrations. It also buffers and regulates gas flow, resulting in more stable gas flow and pressure entering the reaction zone, which is beneficial for the stable progress of the reaction.
[0016] In some preferred embodiments, the heat exchanger is connected to the gas outlet pipe via a heat exchange outlet pipe.
[0017] In some preferred embodiments, the reactor is located above the heat exchanger with an exhaust gas outlet, through which the waste gas generated during the reaction can be discharged.
[0018] In some preferred embodiments, the product discharge device is connected to the center of the cross-section of the gas distributor.
[0019] In some preferred embodiments, two or more nozzles are evenly distributed around the center of the gas distributor's cross-section; the nozzles are connected to the raw material gas inlet pipe. By installing two or more nozzles within the reactor, mass production of granular silicon can be achieved. If the reactor is large-scale and has a high production capacity, the number of nozzles needs to be increased to ensure that the reactants enter the reactor evenly, improving reaction efficiency and product quality. Multiple nozzles can simultaneously inject reactants into the reactor, resulting in a more uniform distribution of the material within the reactor and avoiding localized over- or under-reaction.
[0020] In some preferred embodiments, a heating device is provided on the side of the reactor corresponding to the reaction zone. The heating device may include one or more combinations of resistance heaters, induction heaters, and microwave heaters. The heating device can be located inside and / or outside the reactor. Placing the heating device in the middle section of the reactor better meets the heat requirements of the reaction. When the heating device is located inside the reactor, it has more direct contact with the reactants, reducing heat loss during the transfer process and improving heating efficiency. Placing the heating device outside the reactor offers advantages such as ease of installation, maintenance, and replacement. External heating devices avoid direct contact with the reactants, reducing the risk of contamination and facilitating monitoring and adjustment. In practical applications, the appropriate location for the heating device needs to be selected based on a comprehensive consideration of the specific structure of the reactor, the properties of the reactants, and the requirements of the production process.
[0021] In some preferred embodiments, the gas distributor has a cavity structure that is connected to the heat exchanger. This connection between the heat exchanger and the gas distributor's cavity structure also allows the gas distributor to connect to the cold gas inlet and outlet pipes, thus better utilizing the heat from the non-deposition zone of the reactor to heat auxiliary carrier gases such as N2. The cavity structure of the gas distributor provides space for heat exchange of the material, allowing the cold material entering the gas distributor from the heat exchanger to be further heated within the cavity. This design effectively avoids localized excessively high or low concentrations of gas and material within the reactor, ensuring the uniformity and stability of the reaction. Simultaneously, the cavity structure of the gas distributor facilitates connection to the heat exchanger. Through a reasonable connection method and structural design, smooth flow of gas and material from the heat exchanger to the distributor can be ensured, reducing flow resistance and increasing heat utilization.
[0022] The cavity structure of the gas distributor is connected to the heat exchanger via a connecting channel, which can be located inside or outside the reactor, depending on the reactor design and process requirements. If the connecting channel is located inside the reactor, it reduces the impact of the external environment on gas and material transport, lowers energy loss, and also contributes to the overall structural stability of the reactor. If the connecting channel is located outside the reactor, it offers advantages in terms of ease of inspection, maintenance, and installation, allowing operation without affecting the normal operation inside the reactor, thus improving the maintainability and reliability of the equipment. Furthermore, externally located connecting channels can be flexibly adjusted and modified according to actual needs to adapt to different production processes and requirements.
[0023] The design of the flow channels in a heat exchanger plays a crucial role in the flow of gas and materials within the reactor. In some preferred embodiments, the cross-sectional diameter of the flow channels ranges from 1 to 100 cm. This is to prevent a significant increase in flow resistance, which could affect the normal progress of the reaction or cause local blockages, thereby reducing reaction efficiency. It also ensures uniform distribution of gas and materials within the channels, achieving an ideal flow guiding effect and guaranteeing reaction stability and product quality. In some preferred embodiments, the channel length ranges from 1 to 50 cm. This aims to ensure efficient material transport while maximizing heat exchange within the channels. By controlling the cross-sectional diameter and channel length within these ranges, smooth flow of gas and materials within the reactor can be ensured, providing favorable conditions for the production of high-purity granular silicon.
[0024] In some preferred embodiments, the heat exchanger's flow channels are inclined holes and / or straight channels with a 10-60 degree angle relative to the vertical direction and a converging tendency at the lower end. This structure better guides gas and material towards the center of the reactor, forming a uniform flow field and avoiding the generation of local eddies. This improves the uniformity and efficiency of the reaction while preventing the accumulation of reactant gas on the reactor wall, thus reducing silicon deposition. In specific cases, the appropriate flow channel form can be selected based on the reactor's specific structure and process requirements to achieve the best flow guidance effect.
[0025] In some preferred embodiments, the heat exchanger is made of one or more combinations of metal silicides, tungsten, tungsten alloys, niobium, niobium alloys, tantalum, and tantalum alloys, which can meet the requirements of the reactor under harsh conditions such as high temperature, high pressure, and strong chemical corrosion. Tungsten, niobium, tantalum metals, and their alloys have good high-temperature strength, thermal stability, and chemical stability, enabling them to withstand the high-temperature environment inside the reactor while also resisting chemical corrosion from the reactants. Heat exchangers made of these materials ensure normal operation within the reactor, effectively guiding the flow of gas and materials, and providing a reliable guarantee for the production of high-purity granular silicon. In practical applications, appropriate materials can be selected to manufacture the heat exchanger according to the specific operating conditions and requirements of the reactor to improve the service life and operating efficiency of the equipment.
[0026] Compared with the prior art, the advantages of this utility model are as follows:
[0027] 1. Low energy consumption: The cavity connection design of the heat exchanger and gas distributor effectively utilizes the heat in the non-deposition zone of the reactor to heat auxiliary carrier gases such as N2, reducing energy waste.
[0028] 2. Effectively avoids silicon deposition. By setting up a heat exchanger and auxiliary gas inlet in the reactor, fine silicon powder and other micro-powders in the reactor can be effectively collected in the deposition zone of the reactor for reuse, increasing production capacity while avoiding silicon deposition.
[0029] 3. High production capacity and low investment: By setting two or more nozzles in the reactor, granular silicon can be produced in large quantities, effectively reducing equipment investment. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of an energy-saving jet-fluidized bed device for producing high-purity granular silicon in a specific embodiment.
[0031] Figure 2 This is a top view of the heat exchanger and the cold gas inlet pipe and heat exchange outlet pipe connected to the heat exchanger in a specific embodiment of an energy-saving sprayed fluidized bed device for producing high-purity granular silicon.
[0032] Figure 3 This is a schematic diagram of the heat exchanger of the energy-saving jet fluidized bed device for producing high-purity granular silicon in a specific embodiment, as well as the cold gas inlet pipe and heat exchange outlet pipe connected to the heat exchanger.
[0033] Figure 4 This is a top view of the gas distributor in an energy-saving jet-fluidized bed device for producing high-purity granular silicon, as described in a specific embodiment. Detailed Implementation
[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.
[0035] See Figures 1 to 4 An energy-saving fluidized bed reactor for producing high-purity granular silicon includes a reactor 1. The middle section of the reactor 1 is the reaction zone. A seed inlet 4 and a heating device 7 are located on the side of the reactor 1 corresponding to the reaction zone. The heating device 7 includes one or more combinations of a resistance heater, an induction heater, and a microwave heater. The heating device 7 is located outside the reactor 1. A heat exchanger 5 is located above the reaction zone inside the reactor 1. The heat exchanger 5 has a flow channel and is connected to a cold gas inlet pipe 5-1. The heat exchanger 5 is also connected to a gas outlet pipe 8 via a heat exchange outlet pipe 5-2. During operation, cold gas can be introduced into the cold gas inlet pipe 5-1, and after passing through the heat exchanger 5, the cold gas flows out from the heat exchange outlet pipe 5-2 and into the gas outlet pipe 8. The cross-sectional diameter of the flow channel of the heat exchanger 5 is 1~100 cm, and the channel length is 1~50 cm. The flow channel of the heat exchanger 5 is an oblique hole and / or a straight channel inclined at 10~60 degrees relative to the vertical direction with a converging tendency at the lower end. The heat exchanger 5 is made of one or more of the following materials: metal silicide, tungsten, tungsten alloy, niobium, niobium alloy, tantalum, and tantalum alloy. The reactor 1, located above the heat exchanger 5, is equipped with an exhaust gas outlet 2, a backup exhaust gas outlet 6 (exhaust gas can be discharged through the backup exhaust gas outlet 6 if necessary), and an auxiliary gas inlet 3. The auxiliary gas inlet 3 is used at least for ventilation to blow the fine powder passing upward through the heat exchanger 5 back to the reaction zone. Furthermore, the auxiliary gas inlet 3 extends above the flow channel of the heat exchanger 5 via a pipeline, which is divided into multiple branches, each corresponding to a flow channel of the heat exchanger 5. Each branch is equipped with a gas flow regulating valve to control the ventilation volume of its corresponding branch. A gas distributor 9 is located below the reaction zone inside the reactor 1. The center of the cross-section of the gas distributor 9 is connected to a product discharge device 10. Two nozzles 14 are evenly distributed around the center of the cross-section of the gas distributor 9; the nozzles 14 are connected to a raw material gas inlet pipe 11. The reactor 1 is located below the gas distributor 9 and is equipped with a gas inlet 12 and an auxiliary carrier gas inlet 13. The gas outlet pipe 8 is connected to the auxiliary carrier gas inlet 13.
[0036] Here is an example of producing high-purity granular silicon using the energy-saving jet-fluidized bed device described above:
[0037] Reactor 1 is preheated to 800-1200°C. Hydrogen and N2 are then introduced into the lower section of reactor 1 through gas inlet 12 and auxiliary carrier gas inlet 13, respectively. These gases are introduced into the reaction zone through gas distributor 9. Subsequently, trichlorosilane feed gas enters feed gas inlet pipe 11 and enters reactor 1 through nozzle 14. Next, granular silicon seeds preheated to 1000-1100°C are added to reactor 1 through seed inlet 4. At this time, the granular silicon seeds are agitated and kept suspended by the reaction gas and auxiliary carrier gas. The temperature of the granular silicon seeds is maintained at 1000-1100°C using heating device 7. At this temperature, hydrogen reduces trichlorosilane, and the generated elemental silicon continuously deposits on the granular silicon seeds. As the reaction proceeds, the granular silicon particles continue to grow. Once they reach the process-set size, they fall to product discharge device 10 due to gravity. Inert gas is introduced into product discharge device 10 to prevent oxidation of the high-temperature product. The waste gas generated by the reaction is discharged through waste gas outlet 2 (if necessary, it can be discharged through backup waste gas outlet 6). After the reaction has been going on for a period of time, the temperature of the non-deposition zone of reactor 1 rises. At this time, N2 enters the heat exchanger 5 through the cold gas inlet pipe 5-1 to absorb the heat of the non-deposition zone. Then, it enters the auxiliary carrier gas inlet 13 through the heat exchange outlet pipe 5-2 and the gas outlet pipe 8, and then enters the reaction zone through the gas distributor 9, so as to achieve the purpose of heat recovery and utilization.
[0038] Furthermore, it should be understood that after reading the above description of this utility model, those skilled in the art can make various alterations or modifications to this utility model, and these equivalent forms also fall within the scope defined by the appended claims.
Claims
1. An energy saving spouted fluid bed apparatus for producing high purity granular silicon, characterized in that, Including reactors; The middle section of the reactor is the reaction zone. A seed inlet is set on the side of the reactor corresponding to the reaction zone. A gas distributor is set below the reaction zone in the reactor. The gas distributor is connected to the raw material gas inlet pipe and the product discharge device. Gas inlet 1 and auxiliary carrier gas inlet are set below the gas distributor in the reactor. A heat exchanger is installed above the reaction zone inside the reactor. The heat exchanger has a flow channel and is connected to a cold gas inlet pipe and a gas outlet pipe. The gas outlet pipe is connected to an auxiliary carrier gas inlet. The reactor is equipped with an auxiliary gas inlet, which is used at least for ventilation to blow the fine powder that has passed through the heat exchanger upward back to the reaction zone of the reactor.
2. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 1 wherein, The auxiliary gas inlet is located above the heat exchanger.
3. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 1 wherein, The auxiliary gas inlet extends through a pipeline to the top of the heat exchanger's flow channel.
4. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 3 wherein, The pipeline is divided into multiple branches, each of which corresponds one-to-one with the flow channel of the heat exchanger.
5. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 4 wherein, Each branch is equipped with a gas flow regulating valve, which is used to control the ventilation volume of the corresponding branch.
6. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 1 wherein, The heat exchanger is connected to the gas outlet pipe via the heat exchange outlet pipe.
7. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 1 wherein, The reactor is located above the heat exchanger and has an exhaust gas outlet.
8. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 1 wherein, The product discharge device is connected to the center of the cross-section of the gas distributor.
9. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon as claimed in claim 1 wherein, Around the center of the cross-section of the gas distributor, there are two or more nozzles evenly distributed on the gas distributor; the nozzles are connected to the raw material gas inlet pipe.
10. The energy-saving jet fluidized bed apparatus for producing high-purity granular silicon according to claim 1, characterized in that, A heating device is installed on the side of the reactor corresponding to the reaction zone.
11. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 10, wherein, The heating device includes one or more combinations of resistance heaters, induction heaters, and microwave heaters.
12. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 10, wherein, The heating device is located inside and / or outside the reactor.
13. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 1, wherein, The gas distributor has a cavity structure, and the cavity structure of the gas distributor is connected to the heat exchanger.
14. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 13, wherein, The cavity structure of the gas distributor is connected to the heat exchanger via a connecting channel located inside and / or outside the reactor.
15. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 1, wherein, The cross-sectional diameter of the heat exchanger's flow channel is between 1 and 100 cm.
16. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 1, wherein, The length of the flow channel in the heat exchanger ranges from 1 to 50 cm.
17. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 1, wherein, The heat exchanger's flow channel is an inclined hole and / or a straight channel that is inclined at 10 to 60 degrees relative to the vertical direction and tends to converge at the lower end.
18. The energy efficient spouted fluid bed apparatus for producing high purity particulate silicon of claim 1, wherein, The heat exchanger is made of one or more of the following materials: metal silicide, tungsten, tungsten alloy, niobium, niobium alloy, tantalum, and tantalum alloy.