Deflagration-proof cyclone filter device

Abstract

An explosion-proof cyclone filter device relates to the field of waste gas treatment technology in monocrystalline silicon production. It includes: an inner cylinder; an outer cylinder fitted around the outer periphery of the inner cylinder, forming a sealed cooling chamber between them; a cooling water pipe installed within the cooling chamber and spirally coiled around the outer wall of the inner cylinder; and an air inlet pipe sealed and connected to the inner cylinder. The cooling water pipe extends from both ends of the outer cylinder, facilitating the introduction of cooling water. This rapidly reduces the temperature of the inner cylinder and red phosphorus dust to below the auto-ignition point of red phosphorus (260°C), thus eliminating the risk of spontaneous combustion of the red phosphorus dust due to high temperatures. Simultaneously, by introducing gas, the cooled red phosphorus dust in the inner cylinder undergoes an oxidation reaction with the gas, thereby achieving the harmless treatment of the red phosphorus dust. The combination of cooling and oxidation effectively prevents explosions during cleaning, thus avoiding damage to the cyclone filter and personal safety hazards to on-site personnel, and preventing fire accidents.

Description

Technical Field

[0001] This invention relates to the field of waste gas treatment technology in monocrystalline silicon preparation, specifically to a cyclone filtration device that is explosion-proof. Background Technology

[0002] In the field of semiconductor single-crystal silicon fabrication, pulling red phosphorus-doped single-crystal silicon rods using a single-crystal furnace is a common process, with red phosphorus being widely used as an n-type dopant. During the single-crystal silicon rod pulling process, high-temperature waste gas containing red phosphorus dust is inevitably generated. To ensure that the waste gas meets emission standards and to achieve effective raw material recovery, a cyclone filtration device is typically used to separate and collect the red phosphorus dust from the waste gas.

[0003] However, after the drawing process, due to the continuous heat exchange from the high-temperature exhaust gas inside the cyclone filter, the temperature of its inner wall and the accumulated red phosphorus dust typically reaches 300°C to 500°C, far exceeding the auto-ignition point of red phosphorus in air (260°C). During normal operation, the filter is in a sealed, negative-pressure state with almost no oxygen, so the red phosphorus dust does not oxidize at high temperatures. However, when the filter is opened for cleaning, a large amount of outside air rushes into it instantly. At this time, the high-temperature red phosphorus dust comes into rapid contact with oxygen in the air, triggering a violent oxidation reaction. This oxidation reaction releases a large amount of heat in a very short time, causing a sudden increase in local temperature and leading to a deflagration of the red phosphorus dust. This deflagration not only damages the filter and other equipment and results in the loss of red phosphorus raw materials, but also poses a serious personal safety hazard to on-site personnel and is highly likely to cause a fire. Summary of the Invention

[0004] In view of this, it is necessary to provide a cyclone filter device that is designed to prevent deflagration, which can cool down the red phosphorus dust inside to a lower temperature environment and cause it to undergo an oxidation reaction, thereby preventing deflagration during the cleaning of red phosphorus dust.

[0005] An explosion-proof cyclone filter includes: an inner cylinder configured to accommodate exhaust gas containing red phosphorus dust; an outer cylinder fitted around the outer periphery of the inner cylinder, forming a sealed cooling chamber between them; a cooling water pipe disposed within the cooling chamber and spirally wound around the outer wall of the inner cylinder, with both ends extending from the cooling chamber to the outside of the outer cylinder, the cooling water pipe being configured to allow cooling water to circulate, thereby reducing the temperature inside the inner cylinder; and an air inlet pipe sealed and connected to the inner cylinder, the air inlet pipe being configured to allow the introduction of gas that undergoes an oxidation reaction with the red phosphorus dust.

[0006] Preferably, a spiral arc-shaped groove is formed on the outer wall of the inner cylinder, the curvature of the arc-shaped groove is the same as the curvature of the cooling water pipe, and part of the outer wall of the cooling water pipe is attached to the arc-shaped groove.

[0007] Preferably, there is an angle between the flow direction of the cooling water in the cooling water pipe and the flow direction of the red phosphorus dust entering the inner cylinder.

[0008] Preferably, the coiling pitch of the cooling water pipe gradually increases along the flow direction of the red phosphorus dust inside the inner cylinder.

[0009] Preferably, the inner wall of the cooling water pipe is provided with multiple turbulence fins, which are arranged at intervals along the extension direction of the cooling water pipe.

[0010] Preferably, the top of the inner cylinder is sealed and connected to an exhaust gas connecting pipe, and an air inlet is provided on the side wall of the exhaust gas connecting pipe, with the air inlet pipe sealed and connected to the air inlet.

[0011] Preferably, a flow regulating valve is installed on the air intake pipe.

[0012] Preferably, a check valve is installed on the air inlet pipe between the air inlet and the flow regulating valve, and the allowable flow direction of the check valve is from the outside of the air inlet pipe to the inside of the air inlet.

[0013] Preferably, the inner cylinder has a conical structure that is smaller at the top and larger at the bottom, so that the red phosphorus dust can be collected at the bottom of the inner cylinder.

[0014] Preferably, the inner wall of the inner cylinder is provided with a high-temperature resistant and non-stick coating.

[0015] The present invention employs the above-mentioned technical solution, and its beneficial effects are as follows: By setting an outer cylinder fitted around the outer circumference of the inner cylinder, and spirally winding cooling water pipes within the cooling chamber between the inner and outer cylinders, efficient cooling of the inner cylinder and the red phosphorus dust inside is achieved. The cooling water pipes extend from both ends of the outer cylinder, facilitating the introduction of cooling water, which can rapidly reduce the temperature of the inner cylinder and the red phosphorus dust to below the auto-ignition point of red phosphorus (260°C), thereby eliminating the risk of spontaneous combustion of the red phosphorus dust due to high temperatures. Simultaneously, by introducing gas, the cooled red phosphorus dust in the inner cylinder undergoes an oxidation reaction with the gas, thereby achieving the harmless treatment of the red phosphorus dust. The combination of cooling and oxidation effectively prevents deflagration during cleaning, thus avoiding damage to the cyclone filter and personal safety hazards to on-site personnel, and preventing fire accidents. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the explosion-proof cyclone filter device provided in an embodiment of the present invention.

[0017] Figure 2 for Figure 1 The main perspective view.

[0018] Figure 3 for Figure 1 Longitudinal section view.

[0019] Figure 4 for Figure 3 A magnified view of part A in the image.

[0020] Figure 5 for Figure 1 A schematic diagram of the cooling water pipe structure of the explosion-proof cyclone filter device.

[0021] In the figure: Inner cylinder 10, arc-shaped groove 11, outer cylinder 20, cooling water pipe 30, air inlet pipe 40, exhaust gas connecting pipe 50, air inlet 51. Detailed Implementation

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Please refer to Figures 1 to 5 This invention provides an explosion-proof cyclone filter device, comprising: an inner cylinder 10, configured to accommodate exhaust gas containing red phosphorus dust; an outer cylinder 20, fitted around the outer periphery of the inner cylinder 10, forming a sealed cooling chamber between the outer and outer cylinders; a cooling water pipe 30, disposed within the cooling chamber and spirally wound around the outer wall of the inner cylinder 10, with both ends of the cooling water pipe 30 extending from the cooling chamber to the outer cylinder 20, and configured to allow cooling water to circulate, thereby reducing the temperature inside the inner cylinder 10; and an air inlet pipe 40, sealed and connected to the inner cylinder 10, configured to allow the introduction of gas that reacts with the red phosphorus dust in an oxidation reaction.

[0024] After cooling water is introduced into the cooling water pipe 30, it can efficiently cool the inner cylinder 10 and the high-temperature red phosphorus dust entering the inner cylinder 10. Since the temperature of the inner cylinder 10 and the accumulated red phosphorus dust is usually as high as 300℃~500℃ after the drawing process, the cooling water pipe 30 can quickly reduce its temperature to below the auto-ignition point of red phosphorus in air (260℃), thereby fundamentally eliminating the risk of severe oxidation and deflagration caused by contact with air during cleaning, significantly improving the safety performance of the equipment. Simultaneously, air can be introduced into the inner cylinder 10 through the air inlet pipe 40. The oxygen in the air reacts with the red phosphorus dust in the inner cylinder 10, causing the red phosphorus dust to oxidize into phosphorus pentoxide. Phosphorus pentoxide does not deflagrate upon contact with air. This method avoids severe oxidation during cleaning, and phosphorus pentoxide is easy to handle, with no toxic gases emitted during cleaning, meeting industrial environmental protection requirements. By combining cooling and oxidation, deflagration during cleaning can be effectively prevented, thereby avoiding damage to the cyclone filter and personal safety hazards to on-site personnel, and preventing fire accidents.

[0025] Specifically, the explosion-proof cyclone filter also includes a sealing cover. Before the red phosphorus dust undergoes its oxidation reaction, to ensure the airtightness of the inner cylinder 10, the sealing cover is located at the inlet of the air inlet pipe 40. The inner cylinder 10 is made of 316L stainless steel, and the outer cylinder 20 is made of 304 stainless steel. The upper and lower ends of both the inner cylinder 10 and the outer cylinder 20 are sealed by welding with sealing flanges, forming a sealed cooling chamber. The inner wall of the inner cylinder 10 forms a cyclone flow channel to achieve cyclone separation of the exhaust gas. A clean gas outlet is also provided at the top of the inner cylinder 10 to allow the separated gas to be discharged. The cyclone flow channel and clean gas outlet can use the structure of existing cyclone separators.

[0026] Furthermore, a spiral arc-shaped groove 11 is formed on the outer wall of the inner cylinder 10. The arc of the arc-shaped groove 11 is the same as the arc of the cooling water pipe 30, and part of the outer wall of the cooling water pipe 30 is attached to the arc-shaped groove 11.

[0027] This fitted structural design increases the contact area between the cooling water pipe 30 and the outer wall of the inner cylinder 10, thereby improving the heat transfer efficiency between them. This allows the cooling water to carry away the heat from the inner cylinder 10 and the red phosphorus dust inside more quickly, enhancing the cooling and anti-explosion effect.

[0028] Furthermore, there is an angle between the flow direction of the cooling water in the cooling water pipe 30 and the flow direction of the red phosphorus dust entering the inner cylinder 10.

[0029] Specifically, the two ends of the cooling water pipe 30 are the upper end and the lower end respectively. The upper end extends out from the upper part of the outer cylinder 20, and the lower end extends out from the lower part of the outer cylinder 20. The lower end is connected to the cooling water source, so that the cooling water enters the cooling water pipe 30 from the lower end and then discharges from the upper end. In this way, the flow direction of the cooling water is from bottom to top, forming a countercurrent heat exchange with the red phosphorus dust flowing from top to bottom in the inner cylinder 10. In this way, the cooling water can always exchange heat with the wall surface of the inner cylinder 10 with a higher temperature during the whole flow process, maintaining a large heat exchange temperature difference, thereby improving the heat exchange efficiency.

[0030] Quick-connect interfaces are provided at both the upper end and the lower end of the cooling water pipe 30 to quickly connect the cooling water source and the circulating water pipe. The cooling water source is industrial deionized water with a temperature of 20°C to 30°C. The cooling water in the cooling water system supporting the single crystal furnace can be used, thereby reducing the cost of additionally installing refrigeration equipment.

[0031] Furthermore, along the flow direction of the red phosphorus dust in the inner cylinder 10, the coiling pitch of the cooling water pipe 30 gradually increases.

[0032] In the upper part of the inner cylinder 10, the coiling pitch of the cooling water pipe 30 is relatively dense, and in the lower part, the coiling pitch is relatively sparse. This design is to accurately match the heat load distribution at different positions of the inner cylinder 10: Since the temperature of the red phosphorus dust is the highest and the heat load is the largest when it first enters the upper part of the inner cylinder 10, more dense cooling water pipes 30 are required for strong cooling; as the red phosphorus dust flows downward and gradually cools, its heat load gradually decreases, so the cooling water pipes 30 in the lower part can be appropriately sparse. In this way, not only can the optimal allocation of cooling resources be achieved, but also the energy waste caused by excessive cooling can be avoided.

[0033] Furthermore, multiple turbulence fins (not shown in the figure) are provided on the inner wall of the cooling water pipe 30, and the multiple turbulence fins are arranged at intervals along the extension direction of the cooling water pipe 30.

[0034] The turbulence fins can break the laminar flow state of the cooling water when it flows in the cooling water pipe 30, enhance the turbulence degree of the cooling water, thereby greatly increasing the convective heat transfer coefficient between the cooling water and the pipe wall of the cooling water pipe 30, making the cooling process more rapid and efficient.

[0035] Furthermore, an exhaust gas connection pipe 50 is hermetically connected to the top of the inner cylinder 10, and an air inlet 51 is provided on the side wall of the exhaust gas connection pipe 50. The intake pipe 40 is hermetically connected to the air inlet 51.

[0036] The exhaust gas connection pipe 50 is used to introduce high-temperature exhaust gas containing red phosphorus dust. An air inlet 51 is provided on the side wall of the exhaust gas connection pipe 50 for connecting the intake pipe 40. The inlet of the intake pipe 40 is provided with a KF16 ultra-high vacuum quick-connect flange standard interface, which is convenient for connecting to the gas source.

[0037] Specifically, the intake pipe 40 has an "L" shaped structure, with one end located outside the exhaust gas connecting pipe 50 and the other end extending into the inner cylinder 10 and coaxial with the exhaust gas connecting pipe 50. This avoids the exhaust gas connecting pipe 50, prevents affecting the separation efficiency of gas and red phosphorus dust in the exhaust gas, and allows the gas to directly enter the inner cylinder 10, preventing gas from leaking out from the exhaust gas connecting pipe 50.

[0038] Furthermore, a flow regulating valve (not shown in the figure) is provided on the intake pipe 40.

[0039] By adjusting the flow regulating valve, the flow rate of gas entering the inner cylinder 10 can be controlled, thereby enabling the cooled red phosphorus dust inside the inner cylinder 10 to undergo a slow and uniform oxidation reaction with the oxygen in the gas, thus achieving the harmless treatment of the red phosphorus dust. Compared with existing technologies that directly open the cover, causing a large influx of air and triggering a deflagration, or that introduce expensive inert gas for replacement, this application achieves safe and low-cost harmless treatment through precise control of gas flow.

[0040] Specifically, the flow control valve uses a needle valve, with a flow rate range of 50 mL / min to 200 mL / min, to adapt to the oxidation requirements of different amounts of red phosphorus dust.

[0041] Furthermore, a check valve (not shown in the figure) is installed on the air inlet pipe 40 between the air inlet 51 and the flow regulating valve. The allowable flow direction of the check valve is from the outside of the air inlet pipe 40 to the inside of the air inlet 51.

[0042] The check valve can effectively prevent the high-temperature exhaust gas in the inner cylinder 10 from being discharged in reverse from the air inlet pipe 40 when the filter device is working normally, that is, when the inner cylinder 10 is in a high-temperature negative pressure state, thereby ensuring the sealing and safety of the entire system and avoiding exhaust gas leakage from polluting the working environment.

[0043] Furthermore, the inner cylinder 10 has a conical structure that is smaller at the top and larger at the bottom, so that the red phosphorus dust can be collected at the bottom of the inner cylinder 10.

[0044] The structural design of the inner cylinder 10 allows red phosphorus dust to slide more smoothly down the inclined inner wall of the inner cylinder 10 under the combined action of gravity and centrifugal force during the cyclone separation process, and eventually accumulate at the bottom of the inner cylinder 10. This not only improves the separation and collection efficiency of red phosphorus dust from other substances in the exhaust gas, but also prevents excessive accumulation of red phosphorus dust on the upper part of the inner cylinder 10 wall, facilitating subsequent centralized treatment and cleaning.

[0045] Furthermore, the inner wall of the inner cylinder 10 is provided with a high-temperature resistant and non-stick coating.

[0046] The high-temperature resistant and non-stick coating can remain stable in high-temperature environments, effectively preventing high-temperature red phosphorus dust from adhering and caking on the inner wall of the inner cylinder 10. This reduces the difficulty of cleaning for workers, lowers maintenance costs, and also avoids potential safety hazards caused by residual red phosphorus dust.

[0047] Furthermore, the bottom of the inner cylinder 10 is provided with a cleaning port (not shown in the figure), and the cleaning port is provided with an openable first sealing door. The bottom of the outer cylinder 20 is provided with a connecting port (not shown in the figure) that is sealed to the cleaning port, and the connecting port is provided with an openable second sealing door. After the red phosphorus dust in the inner cylinder 10 has cooled and oxidized, the first sealing door and the second sealing door are opened in sequence to expose the cleaning port in order to clean the oxidation products in the inner cylinder 10.

[0048] The explosion-proof cyclone filter of this application operates in three stages: normal filtration, cooling and slow oxidation, and safety cleaning, as detailed below:

[0049] 1. Normal filtration stage

[0050] S11. Close the flow regulating valve on the air inlet pipe 40, and cover it with the sealing cap to ensure the airtightness of the filter device.

[0051] S12. Turn on the cooling water source and let the cooling water circulate in the cooling water pipe 30 at a flow rate of 0.5m³ / h~1m³ / h to cool the inner cylinder 10 wall and prevent the high temperature exhaust gas from burning the inner cylinder 10 wall.

[0052] S13. The high-temperature exhaust gas containing red phosphorus dust generated during the pulling of red phosphorus doped products in the single crystal furnace enters the inner cylinder 10 through the exhaust gas connecting pipe 50. Through the cyclone separation, the red phosphorus dust settles to the bottom of the inner cylinder 10, and the separated gas is discharged from the clean gas outlet set at the top of the inner cylinder 10.

[0053] S14. During this stage, the inner cylinder 10 is under negative pressure, and no oxygen enters. The red phosphorus dust only accumulates and does not oxidize.

[0054] 2. Cooling and slow oxidation stage

[0055] After the single crystal furnace pull is completed, the exhaust gas stops entering the inner cylinder 10.

[0056] S21. Continue to perform step S12, keep the cooling water circulating in the cooling water pipe 30, continue to cool the inner cylinder 10, and gradually reduce the temperature of the inside of the inner cylinder 10 and the accumulated red phosphorus dust to below 200°C through heat exchange.

[0057] S22. Open the sealing cover, adjust the flow regulating valve, and slowly introduce air into the inner cylinder 10 through the air inlet pipe 40, with the introduction rate controlled at 50mL / min~200mL / min.

[0058] S23. The air entering the inner cylinder 10 comes into slow contact with the red phosphorus dust and undergoes a slow oxidation reaction. The heat released by the reaction is absorbed by the cooling water in the cooling water pipe 30. The temperature inside the inner cylinder 10 is always maintained below 200℃, and there is no local high temperature accumulation.

[0059] S24. The slow oxidation process lasts for 60 to 120 minutes. When there is no obvious heat release in the inner cylinder 10 and the temperature remains stable, it is determined that the red phosphorus dust in the inner cylinder 10 has been basically oxidized, and the flow regulating valve is closed.

[0060] 3. Safety Cleanup Phase

[0061] S31. Turn off the cooling water source and stop supplying cooling water into the cooling water pipe 30;

[0062] S32. Open the first and second sealing doors and clean the residual oxidation products (phosphorus pentoxide) inside the inner cylinder 10 through the cleaning port. At this time, the temperature inside the inner cylinder 10 is below 200°C, and the red phosphorus dust has been oxidized. There is no risk of explosion and the operation is safe.

[0063] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A cyclone filtration device with explosion-proof properties, characterized in that, include: The inner cylinder is designed to accommodate exhaust gas containing red phosphorus dust. The outer cylinder is fitted around the outer periphery of the inner cylinder, and a sealed gap is formed between the outer cylinder and the inner cylinder; A cooling water pipe is disposed within the gap and spirally wound around the outer wall of the inner cylinder. Both ends of the cooling water pipe extend from the gap to the outside of the outer cylinder. The cooling water pipe is configured to allow cooling water to flow through, thereby reducing the temperature inside the inner cylinder. An air inlet pipe is sealed and connected to the inner cylinder, and the air inlet pipe is configured to allow the introduction of gas that reacts with red phosphorus dust to undergo an oxidation reaction.

2. The explosion-proof cyclone filter device as described in claim 1, characterized in that, A spiral arc-shaped groove is formed on the outer wall of the inner cylinder. The arc of the arc-shaped groove is the same as the arc of the cooling water pipe. Part of the outer wall of the cooling water pipe is attached to the arc-shaped groove.

3. The explosion-proof cyclone filter device as described in claim 1, characterized in that, There is an angle between the flow direction of the cooling water in the cooling water pipe and the flow direction of the red phosphorus dust entering the inner cylinder.

4. The explosion-proof cyclone filter device as described in claim 1, characterized in that, Along the flow direction of the red phosphorus dust inside the inner cylinder, the coiling pitch of the cooling water pipe gradually increases.

5. The explosion-proof cyclone filter device as described in claim 1, characterized in that, The inner wall of the cooling water pipe is provided with multiple turbulence fins, which are arranged at intervals along the extension direction of the cooling water pipe.

6. The explosion-proof cyclone filter device as described in claim 1, characterized in that, The top of the inner cylinder is sealed and connected to a feed pipe, and an air inlet is provided on the side wall of the feed pipe. The air inlet pipe is sealed and connected to the air inlet.

7. The explosion-proof cyclone filter device as described in claim 6, characterized in that, The intake pipe is equipped with a flow regulating valve.

8. The explosion-proof cyclone filter device as described in claim 7, characterized in that, A check valve is provided on the air intake pipe between the air inlet and the flow regulating valve. The allowable flow direction of the check valve is from outside the air intake pipe to inside the air inlet.

9. The explosion-proof cyclone filter device as described in claim 1, characterized in that, The inner cylinder has a conical structure that is smaller at the top and larger at the bottom, so that red phosphorus dust can accumulate at the bottom of the inner cylinder.

10. The explosion-proof cyclone filter device as described in claim 1, characterized in that, The inner wall of the inner cylinder is provided with a high-temperature resistant and non-stick coating.

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