Polycrystalline silicon tail gas absorbing and washing device

Abstract

The utility model provides a polycrystalline silicon tail gas absorbing and washing device and relates to the field of tail gas treatment. Comprising a venturi tube, the upper part of the side wall of the venturi tube is provided with a gas inlet for introducing tail gas to be treated, and the bottom of the venturi tube is provided with a gas-liquid outlet for discharging a gas-liquid mixture; the liquid inlet pipe vertically penetrates through the top of the Venturi pipe, and the bottom end of the liquid inlet pipe downwards extends to the contraction section of the Venturi pipe; the flushing pipe is connected to the bottom end of the liquid inlet pipe, the flushing pipe is of a Venturi structure, and a plurality of spraying holes are formed in the side wall of the contraction section of the flushing pipe in the circumferential direction of the flushing pipe. The polycrystalline silicon tail gas absorption efficiency can be improved, silicon powder deposited in the gas-liquid mixing cavity of the Venturi tube is effectively washed, and a gas flow channel is effectively prevented from being blocked.

Description

Technical Field

[0001] This utility model relates to the field of exhaust gas treatment, and more specifically, to a polycrystalline silicon exhaust gas absorption and scrubbing device. Background Technology

[0002] In the polysilicon production process, exhaust gas treatment is a crucial step. Within this process, the Venturi mixer is one of the core components of the exhaust gas absorption system.

[0003] However, during the operation of the Venturi mixer, the polysilicon tail gas contains chlorosilanes, which undergo hydrolysis within the Venturi mixing chamber, producing a large amount of silica. This silica gradually deposits within the Venturi gas-liquid mixing chamber. As the equipment operates for longer periods, the deposited silica accumulates, narrowing the space within the Venturi gas-liquid mixing chamber until blockage occurs. Once the Venturi mixer channels are blocked, it severely affects the normal absorption and treatment of polysilicon tail gas, thus impacting the normal operation of polysilicon production. Utility Model Content

[0004] The purpose of this invention is to provide a polycrystalline silicon tail gas absorption and washing device, which can improve the absorption efficiency of polycrystalline silicon tail gas and effectively flush the silicon powder deposited in the gas-liquid mixing chamber of the venturi tube, effectively preventing the gas flow channel from being blocked.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0006] A polycrystalline silicon tail gas absorption and scrubbing device, comprising:

[0007] A venturi tube, wherein the upper part of the side wall of the venturi tube is provided with an air inlet for introducing the exhaust gas to be treated, and the bottom of the venturi tube is provided with a gas-liquid outlet for discharging the gas-liquid mixture.

[0008] The inlet pipe is vertically inserted through the top of the venturi tube, and its bottom end extends downward to the constricted section of the venturi tube.

[0009] A flushing tube is connected to the bottom end of the inlet tube. The flushing tube has a venturi structure, and its constriction section sidewall has multiple spray holes along its circumference.

[0010] Furthermore, in this invention, the bottom end of the inlet pipe is provided with a connecting part with a tapered structure, and the flushing pipe is detachably connected to the connecting part.

[0011] Furthermore, in this invention, the constricted section sidewall of the venturi tube is provided with an inspection window, and the inspection window is provided with a sealing cover.

[0012] Furthermore, in this invention, the air inlet is inclined downwards, and the air intake direction of the air inlet is perpendicular to the liquid spraying direction of the spray hole.

[0013] Furthermore, in this invention, the plurality of spray holes are arranged in a spiral pattern on the constricted section of the rinsing pipe.

[0014] Furthermore, in this invention, the diameter of the spray hole is 5mm-10mm and the pitch is 8mm-12mm.

[0015] Furthermore, in this invention, differential pressure sensors are respectively provided in the constriction section, throat, and expansion section of the venturi tube.

[0016] Furthermore, in this invention, the inner wall of the constricted section of the venturi tube is provided with a silicon carbide coating.

[0017] Furthermore, in this invention, the thickness of the silicon carbide coating is 0.2mm-0.5mm, and the surface roughness Ra≦0.8μm.

[0018] Furthermore, in this invention, the Venturi tube and the inlet tube are both made of titanium-steel composite material, and the flushing tube is made of silicon carbide material.

[0019] This utility model has at least the following advantages or beneficial effects:

[0020] This invention features a vertically inserted liquid inlet pipe at the top of a venturi tube, extending downwards to the constriction section of the venturi tube. A flushing pipe is located at this end, and liquid is pumped in through the inlet pipe and flows downwards to the flushing pipe. Multiple spray holes are arranged circumferentially along the constriction section of the flushing pipe, forming an annular liquid film covering the inner wall of the venturi tube throat. Part of the liquid is atomized from these spray holes and then sheared and atomized again by a high-speed airflow, thus absorbing the exhaust gas entering from the venturi tube's air inlet and flushing away deposited silicon powder. Simultaneously, some flushing liquid flows out from the bottom of the flushing pipe, colliding with the high-speed airflow after acceleration in the constriction section, further shearing and atomizing the liquid. This achieves effective absorption of the exhaust gas and flushing of the silicon powder deposited in the gas-liquid mixing chamber, effectively preventing gas flow channel blockage. This application improves the absorption efficiency of polycrystalline silicon exhaust gas and effectively flushes away the silicon powder deposited in the gas-liquid mixing chamber of the venturi tube, effectively preventing gas flow channel blockage. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the polycrystalline silicon tail gas absorption and scrubbing device provided in the embodiment of the application;

[0023] Figure 2 A schematic diagram of the flushing tube provided in the embodiment of the application.

[0024] Reference numerals: 1-Venturi tube, 11-Air inlet, 12-Gas-liquid outlet, 13-Inspection window, 14-Sealing cover, 2-Liquid inlet pipe, 21-Connection, 3-Flushing pipe, 31-Spray hole. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Example

[0027] Please refer to Figures 1-2 The figure shown is a schematic diagram of the structure of the polycrystalline silicon tail gas absorption and scrubbing device in an embodiment of this utility model.

[0028] This embodiment provides a polycrystalline silicon tail gas absorption and scrubbing device, including a venturi tube 1. An air inlet 11 is provided on the upper side wall of the venturi tube 1, extending outwards for a certain length to allow tail gas with a certain velocity to be introduced. After being accelerated through the converging section of the venturi tube 1, a high-speed airflow (generally ≥25m / s) is formed, enabling shearing of the introduced liquid. A gas-liquid outlet 12 is provided at the bottom of the venturi tube 1, i.e., the bottom of its expansion section is used to discharge the gas-liquid mixture. A liquid inlet pipe 2 is vertically inserted through the top of the venturi tube 1, with its bottom end extending downwards to the converging section of the venturi tube 1. Liquid is pumped into the liquid inlet pipe 2, flowing axially downwards to the converging section of the venturi tube 1, where the tail gas can be absorbed and the attached silicon powder can be washed away. The bottom end of the liquid inlet pipe 2 is connected to the flushing pipe 3. The flushing pipe 3 has a Venturi structure, which can accelerate the liquid through cross-sectional changes. Multiple spray holes 31 are opened along its axial direction on the side wall of its converging section. After the liquid is accelerated, it is sprayed out in a ring from the multiple spray holes 31 to form an annular liquid film covering the inner wall of the Venturi tube 1. The liquid is broken into droplets, which can atomize and spray the airflow to absorb it, improve the exhaust gas absorption efficiency, and suppress the deposition of SiO2 through continuous flushing. It is set in the converging section, and its spray direction can form an opposing angle with the airflow so that the spray can cover the entire circumference of the inner wall of the Venturi tube 1, avoiding the accumulation of silicon powder caused by dry walls.

[0029] As an example, the bottom end of the aforementioned inlet pipe 2 is provided with a tapered connecting portion 21, meaning the bottom diameter of the inlet pipe 2 decreases. This allows the liquid to be accelerated once by the inlet pipe 2 before entering the flushing pipe 3, and then accelerated a second time by the venturi structure of the flushing pipe 3. Through the secondary venturi structure, combined with the washing pressure (liquid pumping pressure), multi-stage atomization of the liquid can be achieved. Specifically, the connecting portion 21 is formed by a constricted section of the venturi structure and a throat section. The constricted section acts as an acceleration unit, while the throat section acts as a connection unit. The flushing pipe 3 is detachably connected to the throat section of the connecting portion 21. Preferably, a threaded connection is used, allowing the flushing pipe 3 to be detached from the inlet pipe 2 for maintenance.

[0030] It should be noted that the aforementioned multi-stage atomization specifically involves the following steps: Liquid with a certain pressure and velocity is first accelerated through the converging section of the inlet pipe 2 and enters the flushing pipe 3. It is then accelerated again by the converging section of the flushing pipe 3, with some liquid being sprayed out from multiple spray holes 31. Due to the pressure and velocity, this liquid is broken and atomized into 100-200 μm droplets at the spray holes 31. After being sprayed into the converging section of the Venturi tube 1, it is sheared by the high-speed airflow and atomized again into even smaller droplets, with a particle size of 50-80 μm. The remaining liquid, after acceleration, exits from the bottom of the flushing pipe 3. Since it remains within the converging section of the Venturi tube 1, it is still sheared and atomized by the high-speed airflow, absorbing the exhaust gas and flushing the inner walls of the converging section and throat, preventing silicon powder adhesion. This structure not only flushes away silicon powder but also improves the absorption efficiency and effect of the exhaust gas.

[0031] As an example, to facilitate the maintenance of the flushing pipe 3, a maintenance window 13 is provided on the side wall of the contraction section of the venturi pipe 1. The maintenance window 13 is provided with a sealing cover 14. When not under maintenance, it is sealed by the sealing cover 14 to prevent gas and liquid leakage.

[0032] As an example, the air inlet 11 is inclined downwards, and the air intake direction of the air inlet 11 is perpendicular to the liquid spraying direction of the spray hole 31. This allows the high-speed airflow and high-speed liquid to collide at a vertical angle, prolonging the gas-liquid contact time, ensuring that the HCl absorption rate in the exhaust gas is ≥99%, and improving the exhaust gas absorption effect.

[0033] As an example, multiple spray holes 31 are spirally arranged in the constricted section of the flushing pipe 3, which can increase the coverage area of ​​the annular liquid film, thereby increasing the contact area with the high-speed airflow, improving the exhaust gas absorption effect, and the silicon powder flushing effect. Preferably, the diameter of the spray holes 31 is 5mm-10mm and the pitch is 8mm-12mm.

[0034] As an example, differential pressure sensors are installed in the contraction section, throat, and expansion section of the aforementioned Venturi tube 1. These sensors detect the pressure difference between different parts, thereby controlling the pumping pressure and flow rate of the liquid. If the pressure difference is too large, it indicates potential blockage of the inner wall of the Venturi tube 1, and the pumping pressure, speed, and flow rate of the liquid can be adjusted accordingly to ensure the stable operation of the exhaust gas absorption system. Automatic control of the flushing frequency and washing pressure through differential pressure sensing effectively prevents blockage of the gas-liquid mixing chamber.

[0035] As an example, the inner wall of the contraction section of the Venturi tube 1 is coated with a silicon carbide coating, which can resist the erosion of high-speed silicon-containing particles, resulting in a long service life and low maintenance frequency of the Venturi tube 1.

[0036] Furthermore, the silicon carbide coating has a thickness of 0.2-0.5 mm and a surface roughness Ra≤0.8 μm, which can reduce the micro-cutting effect during particle impact.

[0037] As an example, the Venturi tube 1 and the liquid inlet tube 2 are both made of titanium steel composite material, and the rinsing tube 3 is made of silicon carbide material, which can effectively extend the service life of the washing device and reduce the frequency of inspection and maintenance.

[0038] As an example, the distance from the outer end of the air inlet 11 to the center line of the liquid inlet pipe 2 is 620 mm, the distance from the outer end of the liquid inlet pipe 2 to its bottom is 871 mm, and the distance from the outer end of the liquid inlet pipe 2 to the bottom of the venturi tube 1 is 2100 mm. By setting the washing device with a suitable length-to-diameter ratio, sufficient contact time between the exhaust gas and the washing liquid can be ensured, ensuring that the exhaust gas is fully absorbed and meets emission standards.

[0039] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A polysilicon off-gas absorption scrubbing apparatus, characterized by, include: A venturi tube, wherein the upper part of the side wall of the venturi tube is provided with an air inlet for introducing the exhaust gas to be treated, and the bottom of the venturi tube is provided with a gas-liquid outlet for discharging the gas-liquid mixture. The inlet pipe is vertically inserted through the top of the venturi tube, and its bottom end extends downward to the constricted section of the venturi tube. A flushing tube is connected to the bottom end of the inlet tube. The flushing tube has a venturi structure, and its constriction section sidewall has multiple spray holes along its circumference.

2. The polysilicon off-gas absorption scrubbing apparatus of claim 1, wherein, The bottom end of the inlet pipe is provided with a tapered connecting part, and the flushing pipe is detachably connected to the connecting part.

3. The polysilicon off-gas absorption scrubbing apparatus of claim 2, wherein, The venturi tube has an inspection window on the side wall of the constriction section, and the inspection window is equipped with a sealing cover.

4. The polycrystalline silicon tail gas absorption and scrubbing device according to claim 1, characterized in that, The air inlet is inclined downwards, and the air intake direction of the air inlet is perpendicular to the liquid spraying direction of the spray hole.

5. The polysilicon off-gas absorption scrubbing apparatus of claim 4, wherein, The plurality of spray holes are arranged in a spiral pattern in the constricted section of the flushing pipe.

6. The polysilicon off-gas absorption scrubbing apparatus of claim 5, wherein, The diameter of the spray holes is 5mm-10mm and the pitch is 8mm-12mm.

7. The polysilicon off-gas absorption scrubbing apparatus of claim 1 or 6, wherein, Differential pressure sensors are respectively installed in the constriction section, throat, and expansion section of the venturi tube.

8. The polysilicon off-gas absorption scrubbing apparatus of claim 1, wherein, The inner wall of the constricted section of the venturi tube is coated with silicon carbide.

9. The polysilicon off-gas absorption scrubbing apparatus of claim 8, wherein, The thickness of the silicon carbide coating is 0.2mm-0.5mm, and the surface roughness Ra≤0.8μm.

10. The polysilicon off-gas absorption scrubbing apparatus of claim 1, wherein, Both the Venturi tube and the inlet tube are made of titanium-steel composite material, and the flushing tube is made of silicon carbide material.

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