Pneumatic drying system for silicon powder recovery
By designing an efficient silicon powder recycling and airflow drying system, using inert gas circulation and cyclone separation technology, the problems of low silicon powder processing efficiency and high energy consumption are solved, and the recycling and reuse of silicon powder and chlorosilane are realized, reducing production costs and environmental pollution.
Patent Information
- Application Number
- CN202422685526.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-05
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2034-11-05
AI Technical Summary
The existing silicon powder treatment methods are inefficient and have high energy consumption, the traditional drying system is unevenly drying, and the silicon powder and chlorosilane are not effectively recovered, resulting in environmental pollution and high production costs.
Design a silicon powder recovery airflow drying system including feed system, circulating air system, airflow drying system, silicon powder recovery system and exhaust gas recovery and treatment system. Using inert gas circulation and high-efficiency airflow drying technology, combined with cyclone separator and filter, high-efficiency drying of silicon powder and condensation recovery of chlorosilane, adopting a modular design to reduce maintenance costs.
Significantly reduce energy consumption and waste emissions, improve silicon powder recycling efficiency, reduce production costs, achieve environmental protection goals, and reduce raw material demand through the recycling and reuse of chlorosilane.
Smart Images
Figure CN223064287U_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of polysilicon production, and particularly to a silicon powder recovery pneumatic drying system. Background Art
[0002] The information provided in this section is only background information related to the present disclosure, and it is not necessarily prior art.
[0003] The invention background of the silicon powder recovery and pneumatic drying system is mainly closely related to the requirements of industries such as semiconductors and solar photovoltaics. In these industries, silicon is a key material for manufacturing transistors, integrated circuits, and solar panels. During the production process, a large amount of silicon powder or silicon chips are generated as by-products or waste, and these silicon powders usually contain high-value pure silicon components. And if the waste generated during the processing of silicon materials is not properly treated, it may cause environmental pollution. By developing effective recovery technologies, environmental pollution can be reduced, meeting the requirements of environmental protection policies.
[0004] Therefore, with the growth of the demand for silicon materials, finding ways to effectively utilize silicon resources has become increasingly important. Recycling silicon powder can reduce the demand for raw materials, lower production costs, and contribute to sustainable development. By recycling silicon powder and reprocessing it, the market demand for high-quality silicon materials can be met.
[0005] Traditional silicon powder treatment methods are often inefficient and energy-consuming. In the past, a large amount of silicon powder or silicon chip by-products or waste in the polysilicon industry were hydrolyzed and finally treated as solid waste. The treatment process incurred a large amount of production costs, and at the same time, the external transportation of solid waste also generated solid waste treatment fees. At the same time, the previous drying systems had characteristics such as low drying efficiency and uneven drying of materials. Summary of the Invention
[0006] To solve the above technical problems, the present invention discloses a silicon powder recovery pneumatic drying system, which can effectively recover silicon powder while ensuring that the quality of the recovered silicon powder meets the standards for reuse.
[0007] A silicon powder recovery pneumatic drying system includes a feeding system, a circulating air system, a pneumatic drying system, a silicon powder recovery system, and a tail gas recovery and treatment system; one end of the pneumatic drying system is connected to the feeding system, the other end of the pneumatic drying system is connected to the silicon powder recovery system, and the circulating air system is respectively connected to the pneumatic drying system, the silicon powder recovery system, and the tail gas recovery and treatment system to circulate gases.
[0008] The feeding system is used to feed wet silicon powder into the drying system. The circulating air system provides a high-temperature drying medium, which is an inert gas, and the medium can be nitrogen. The pneumatic drying system mixes the wet silicon powder with hot air here and quickly dries it. The silicon powder recovery system is used to separate the dried silicon powder from the air flow. The tail gas recovery and treatment system condenses the evaporated chlorosilane into a liquid after secondary cooling for recovery.
[0009] Furthermore, the circulating air system includes a preheater, a circulating fan, a precooler, and a hot air heater; the circulating fan is connected to the preheater to convey gas, the preheater is connected to the hot air heater, the hot air heater is connected to the pneumatic drying system, the pneumatic drying system is connected to the silicon powder recovery system, the silicon powder recovery system is connected to the preheater to circulate gas, the preheater is connected to the precooler, the precooler is connected to the tail gas recovery and treatment system, and the precooler is connected to the circulating fan to convey the treated gas.
[0010] Furthermore, the feeding system includes a wet material transfer tank and a screw conveyor; the wet material transfer tank is connected to the screw conveyor, and the screw conveyor is connected to the pneumatic drying system to convey wet materials.
[0011] Furthermore, the pneumatic drying system includes a cage crusher and a pneumatic drying cylinder; the cage crusher is arranged at the bottom of the pneumatic drying cylinder, and the pneumatic drying cylinder is connected to the silicon powder recovery system.
[0012] Furthermore, the silicon powder recovery system includes a cyclone separator and a filter; the cyclone separator is connected to the filter, and the filter is connected to the circulating air system.
[0013] Furthermore, the cyclone separator is provided with a switching valve. At the initial stage of driving, if the drying is not thorough, the silicon powder separated by the cyclone separator can be sent back to the drying system again through the screw conveyor by means of the switching valve.
[0014] Furthermore, the tail gas recovery and treatment system includes a chlorosilane cooler and a chlorosilane collection tank; one end of the chlorosilane cooler is connected to the circulating air system, the other end of the chlorosilane cooler is connected to the chlorosilane collection tank, and there is a return air pipeline between the chlorosilane cooler and the circulating air system to convey the treated gas. The chlorosilane collection tank is provided with a chlorosilane external delivery pump.
[0015] The gas after passing through the cyclone separator still contains fine particles and chlorosilane, and needs to be further purified by the filter. The vaporized chlorosilane is recovered and treated through the preheater, the precooler, and the chlorosilane cooler. The condensed chlorosilane liquid enters the chlorosilane collection tank, and after the chlorosilane collection tank reaches a certain liquid level, it is sent out by the chlorosilane external delivery pump to achieve the recycling and reuse of chlorosilane.
[0016] Furthermore, sensors are respectively provided for the feeding system, the circulating air system, the pneumatic drying system, the silicon powder recovery system, and the tail gas recovery and treatment system. The system includes a control system, which consists of sensors disposed in each system to monitor and control the operating parameters of the entire system.
[0017] The utility model discloses a pneumatic drying system for silicon powder recovery, which condenses and recovers the separated chlorosilane while recovering silicon powder. Through efficient pneumatic drying technology and the recycling of inert gas, the energy consumption and waste emissions are significantly reduced, achieving the goal of energy conservation and environmental protection.
[0018] Adopting modular design enables each component to be independently maintained and replaced, reducing maintenance costs and downtime. The internal structure is designed to be easily cleaned, such as detachable internal components, facilitating regular cleaning to keep the equipment in the best operating condition.
[0019] The optimized drying process and equipment design ensure that the silicon powder is fully dried, reducing the loss of silicon powder. During the drying process of silicon powder, a large amount of nitrogen is usually used as the drying medium. Through a series of equipment, including cyclone separators, filters, pre-coolers, and chlorosilane coolers, the effective recovery and reuse of nitrogen are achieved, thereby reducing production costs and improving overall efficiency. By using heat and cold recovery technologies, the heat and cold generated during the drying process are reused for the drying process or other technological processes to reduce energy consumption. Description of the Drawings
[0020] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.
[0021] Figure 1 It is a system diagram of the utility model. Specific Embodiments
[0022] 1 - Wet material transfer tank; 2 - Screw conveyor; 3 - Cage crusher; 4 - Pneumatic drying cylinder; 5 - Cyclone separator; 6 - Filter; 7 - Preheater; 8 - Circulating fan; 9 - Pre-cooler; 10 - Chlorosilane cooler; 11 - Chlorosilane collection tank; 12 - Chlorosilane external delivery pump; 13 - Hot air heater; 14 - Silicon powder dry material discharge port; 15 - Silicon powder collection port; 16 - Conversion valve; 17 - Freon inlet; 18 - Freon outlet; 19 - Nitrogen supplement port; 20 - Nitrogen discharge port.
[0023] A silicon powder recovery pneumatic drying system, comprising a feeding system, a circulating air system, a pneumatic drying system, a silicon powder recovery system, and a tail gas recovery and treatment system; one end of the pneumatic drying system is connected to the feeding system, the other end of the pneumatic drying system is connected to the silicon powder recovery system, and the circulating air system is respectively connected to the pneumatic drying system, the silicon powder recovery system, and the tail gas recovery and treatment system to circulate gas.
[0024] The circulating air system includes a preheater 7, a circulating fan 8, a precooler 9, and a hot air heater 13; the circulating fan 8 is connected to the preheater 7 to convey gas, the preheater 7 is connected to the hot air heater 13, the hot air heater 13 is connected to the pneumatic drying system, the pneumatic drying system is connected to the silicon powder recovery system, the silicon powder recovery system is connected to the preheater 7 to circulate gas, the preheater 7 is connected to the precooler 9, the precooler 9 is connected to the tail gas recovery and treatment system, the precooler 9 is connected to the circulating fan 8 to convey the treated gas, and a nitrogen supplement port 19 and a nitrogen discharge port 20 are provided in the connecting pipeline between the precooler 9 and the circulating fan 8 for adding and replacing inert gas and dealing with a small amount of leakage of nitrogen during circulation.
[0025] The feeding system includes a wet material transfer tank 1 and a screw conveyor 2; the wet material transfer tank 1 is connected to the screw conveyor 2, and the screw conveyor 2 is connected to the pneumatic drying system to convey wet material.
[0026] The pneumatic drying system includes a cage crusher 3 and a pneumatic drying cylinder 4; the cage crusher 3 is arranged at the bottom of the pneumatic drying cylinder 4, and the pneumatic drying cylinder 4 is connected to the silicon powder recovery system.
[0027] The silicon powder recovery system includes a cyclone separator 5 and a filter 6; the cyclone separator 5 is connected to the filter 6, and the filter 6 is connected to the circulating air system.
[0028] The cyclone separator 5 is provided with a conversion valve 16.
[0029] The tail gas recovery and treatment system includes a chlorosilane cooler 10 and a chlorosilane collection tank 11; one end of the chlorosilane cooler 10 is connected to the circulating air system, the other end of the chlorosilane cooler 10 is connected to the chlorosilane collection tank 11, and a return air pipeline is provided between the chlorosilane cooler 10 and the circulating air system to convey the treated gas. The chlorosilane cooler 10 is provided with a Freon inlet 17 and a Freon outlet 18.
[0030] Working principle The working process is as follows:
[0031] Feeding: The by-products or wastes containing chlorosilane and silicon powder are sent from the wet material transfer tank 1 to the bottom of the pneumatic drying cylinder 4 through the screw conveyor 2. The wet material is crushed by the cage crusher 3 to facilitate the uniform distribution of the material in the pneumatic drying cylinder 4. By precisely controlling the speed of nitrogen (inert gas) entering from the bottom, the particulate matter is in a suspended and slowly rising state.
[0032] Heating: The recycled nitrogen sent by the circulation fan 8 is preheated by the preheater 7 with the hot air from the pneumatic drying cylinder 4, achieving the purpose of preheating and precooling simultaneously, and maximizing the energy recovery. The hot nitrogen preheated by the preheater 7 is adjusted in temperature by the hot air heater 13 to adapt to the characteristics of different materials, and then enters the pneumatic drying cylinder 4 after being mixed with the materials in the feeding system.
[0033] Drying: The wet silicon powder is rapidly dispersed in the pneumatic drying cylinder 4 under the action of high-speed air flow and comes into full contact with the hot nitrogen, and the chlorosilane in the silicon powder evaporates rapidly.
[0034] Separation: The dried silicon powder enters the cyclone separator 5 with the air flow and is separated under the action of centrifugal force. In the initial stage of operation, if the drying is not thorough, the silicon powder separated by the cyclone separator 5 can be sent back to the drying system again through the screw conveyor 2 by means of the switching valve 16.
[0035] Tail gas recovery and treatment: The gas after passing through the cyclone separator still contains fine particles and chlorosilane, and needs to be further purified by the filter 6. The vaporized chlorosilane is recovered and treated by the preheater 7, precooler 9, and chlorosilane cooler 10. The condensed chlorosilane liquid enters the chlorosilane collection tank 11, and is sent out by the chlorosilane external delivery pump 12 after the chlorosilane collection tank 11 reaches a certain liquid level, so as to achieve the recycling and reuse of chlorosilane.
[0036] Collection and packaging: The dried and separated silicon powder is collected through the silicon powder dry material discharge port 14 and the silicon powder collection port 15, and can be further processed or packaged according to needs.
[0037] The feeding system, circulation air system, pneumatic drying system, silicon powder recovery system, and tail gas recovery and treatment system are respectively equipped with sensors. The sensor monitoring system ensures the normal operation of the system. It includes temperature control to precisely control the hot air temperature to ensure drying efficiency and product quality; gas flow rate adjustment to adjust the air flow rate according to the material characteristics and production requirements; and automatic monitoring to achieve real-time monitoring and automatic adjustment of the drying process using sensors and controllers.
[0038] The system feeds materials through the screw conveyor 2 and adds a cage crusher 3 at the bottom of the pneumatic drying cylinder 4, enabling the material to be dispersed more quickly and come into full contact with the hot air, enhancing the material dispersion and thus improving the drying efficiency.
[0039] Add waste heat recovery devices, such as preheater 7 and precooler 9, to recover the heat and cold in the discharged circulating nitrogen, reduce energy consumption, and reduce the usage of fresh nitrogen by recycling the drying medium (such as nitrogen).
[0040] Adopt modular design so that each component can be independently maintained and replaced, reduce maintenance costs and downtime, and design an internal structure that is easy to clean, such as detachable internal components, to facilitate regular cleaning and keep the equipment in the best operating condition.
[0041] The tail gas treatment system extracts by-products while treating the tail gas, and adopts more efficient filtration technology and harmful substance capture technology to ensure compliance with emissions standards.
[0042] This solution is applied to the silicon powder recovery scenario with a solid content of 0.06% in the slurry. The gas velocity is controlled and adjusted according to the moisture content, which is 300 - 1000 Nm3 / h. The daily dry recovery of silicon powder reaches 8t, and the annual recovery of silicon powder reaches 2336t. In this scenario, compared with the environmental protection treatment of the traditional process, the electricity consumption for treatment is reduced from 450 KWH / t to 312 KWH / t. In the traditional environmental protection treatment, the sewage treatment cost is 6534 yuan / t, and the solid waste treatment cost is 346.8 yuan / t. This solution not only has no sewage treatment cost, but also can sell the obtained silicon powder and chlorosilane to make a profit of 1500 yuan / t.
[0043] The present invention provides an idea and method for a silicon powder recovery pneumatic drying system. There are many methods and ways to specifically implement this technical solution. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be realized by existing technologies.
Claims
1. A silicon powder recovery pneumatic drying system, characterized in that, It includes a feeding system, a circulating air system, a pneumatic drying system, a silicon powder recovery system, and a tail gas recovery and treatment system; one end of the pneumatic drying system is connected to the feeding system, the other end of the pneumatic drying system is connected to the silicon powder recovery system, and the circulating air system is respectively connected to the pneumatic drying system, the silicon powder recovery system, and the tail gas recovery and treatment system to circulate gas.
2. The silica powder recovery pneumatic drying system according to claim 1, wherein The circulating air system includes a preheater (7), a circulating fan (8), a precooler (9), and a hot air heater (13); the circulating fan (8) is connected to the preheater (7) to transport gas, the preheater (7) is connected to the hot air heater (13), the hot air heater (13) is connected to the pneumatic drying system, the pneumatic drying system is connected to the silicon powder recovery system, the silicon powder recovery system is connected to the preheater (7) to circulate gas, the preheater (7) is connected to the precooler (9), the precooler (9) is connected to the tail gas recovery and treatment system, and the precooler (9) is connected to the circulating fan (8) to transport the treated gas.
3. The silica powder recovery pneumatic drying system according to claim 1, characterized in that The feeding system includes a wet material transfer tank (1) and a screw conveyor (2); the wet material transfer tank (1) is connected to the screw conveyor (2), and the screw conveyor (2) is connected to the pneumatic drying system to transport wet material.
4. The silica powder recovery pneumatic drying system according to claim 1, characterized in that The pneumatic drying system includes a cage crusher (3) and a pneumatic drying cylinder (4); the cage crusher (3) is arranged at the bottom of the pneumatic drying cylinder (4), and the pneumatic drying cylinder (4) is connected to the silicon powder recovery system.
5. The silica powder recovery pneumatic drying system according to claim 1, characterized in that The silicon powder recovery system includes a cyclone separator (5) and a filter (6); the cyclone separator (5) is connected to the filter (6), and the filter (6) is connected to the circulating air system.
6. The silica powder recovery pneumatic drying system according to claim 5, wherein The cyclone separator (5) is provided with a switching valve (16).
7. The silica powder recovery pneumatic drying system according to claim 1, characterized in that, The tail gas recovery and treatment system includes a chlorosilane cooler (10) and a chlorosilane collection tank (11); one end of the chlorosilane cooler (10) is connected to the circulating air system, the other end of the chlorosilane cooler (10) is connected to the chlorosilane collection tank (11), and a return air pipeline is provided between the chlorosilane cooler (10) and the circulating air system to transport the treated gas.
8. The silica powder recovery pneumatic drying system according to claim 7, wherein The chlorosilane cooler (10) is provided with a Freon inlet (17) and a Freon outlet (18).
9. The silica powder recovery pneumatic drying system according to claim 1, wherein The gas is an inert gas.
10. The silica powder recovery pneumatic drying system according to claim 1, characterized in that, Sensors are respectively provided in the feeding system, the circulating air system, the pneumatic drying system, the silicon powder recovery system, and the tail gas recovery and treatment system.