A system for treating off-gases of silanes and chlorosilanes

Abstract

The utility model relates to the technical field of silane and chlorosilane waste gas treatment, specifically to a kind of waste gas treatment system of silane and chlorosilane, and gas input pipeline is connected, including silane processing group and chlorosilane processing group;Silane processing group includes silane accident processing unit and silane tail gas processing unit;Silane accident processing unit includes the first liquid separator of being connected and combustion tower;Combustion tower inside top is provided with spray mechanism, inside is also provided with the nitrogen gas pipeline and combustion pipeline of being connected;Chlorosilane processing group includes chlorosilane accident processing unit and chlorosilane tail gas processing unit;Chlorosilane accident processing unit includes the chlorosilane accident condenser of being connected, chlorosilane accident cryogenic unit and second liquid separator, and gas phase recovery unit and liquid phase recovery unit are connected respectively with second liquid separator.Processing system can handle silane and chlorosilane simultaneously, processing process meets environmental protection standard, realizes pollution-free discharge, effectively handles silane and recycles chlorosilane, reduces waste.

Description

Technical Field

[0001] This utility model relates to the field of silane and chlorosilane waste gas treatment technology, specifically a silane and chlorosilane waste gas treatment system. Background Technology

[0002] Silane waste gas is a colorless, odorless gas that reacts with air, causing asphyxiation. It burns upon contact with air, releasing dense, white amorphous silica fumes. Currently, the main method for treating this type of process waste gas is incineration. However, if the pressure or velocity is too high during the introduction of silane waste gas, it can easily trigger a delayed explosion.

[0003] Currently, common methods for treating chlorosilane waste gas include alkaline scrubbing and regenerative thermal oxidizer (RTO). Alkaline scrubbing is low-cost but presents safety hazards and resource waste; RTO has high energy consumption and investment, lacks a recycling component leading to resource waste, and cannot achieve the recovery and reuse of chlorosilanes. Utility Model Content

[0004] To address the technical problems existing in the background art, this utility model provides a waste gas treatment system for silane and chlorosilane.

[0005] The technical solution of this utility model is as follows: A waste gas treatment system for silane and chlorosilane, connected to a gas input pipeline, includes a silane treatment group and a chlorosilane treatment group; The silane treatment group includes a silane emergency response unit and a silane tail gas treatment unit; The silane accident handling unit includes a first liquid separator and a combustion tower connected together, wherein the first liquid separator is connected to a gas input pipeline; A spraying mechanism is installed on the top of the inner side of the combustion tower, and nitrogen pipelines and combustion pipelines are also installed on the inner side; The chlorosilane treatment group includes a chlorosilane accident handling unit and a chlorosilane tail gas treatment unit; The chlorosilane accident handling unit includes a chlorosilane accident condenser, a chlorosilane accident cryostat, and a second liquid separator connected to each other, as well as a gas phase recovery unit and a liquid phase recovery unit connected to the second liquid separator, wherein the chlorosilane accident condenser is connected to a gas input pipeline.

[0006] The nitrogen pipeline design serves a dual purpose: firstly, it can purge solid particles that fall onto the surface of the combustion tower, preventing blockage; secondly, nitrogen can regulate the silane concentration, control the combustion rate, and ensure complete combustion.

[0007] The spray system utilizes the chimney effect of the combustion tower to concentrate oxygen in the air, ensuring a more complete reaction within the tower and guaranteeing incomplete combustion. It also causes small solid particles carried in the airflow to condense into larger particles, which then settle due to gravity, preventing them from being released into the atmosphere and further enhancing environmental protection. Simultaneously, it can also treat residual silane from incomplete combustion, preventing its release into the atmosphere.

[0008] Variable frequency circulating pumps are installed in the silane tail gas treatment unit, the chlorosilane tail gas treatment unit, and the gas phase recovery unit.

[0009] A variable frequency circulating pump is an intelligent device that adjusts the flow rate by changing the motor speed. Its advantage lies in achieving precise control and efficient operation through variable frequency technology, thereby controlling the recycling of sprayed alkaline solution.

[0010] The chlorosilane emergency cryostat is equipped with a refrigeration unit, a first valve, and a second valve. The first valve is connected to the refrigerant outlet of the chlorosilane emergency cryostat and the refrigeration unit at both ends, respectively. The second valve is connected to the refrigerant outlet of the chlorosilane emergency cryostat and is designed to vent excess refrigerant.

[0011] This application designs a two-stage condensation method to recover chlorosilanes from the chlorosilane emergency response unit. The operation is simple and pollution-free. The chlorosilane emergency condenser uses circulating water, and the chlorosilane emergency cryocooler uses a -45°C refrigerant, enabling thorough, efficient, and safe recovery of chlorosilanes.

[0012] The system of this application also includes an exhaust stack. The chlorosilane tail gas treatment unit includes a third absorption tower, a fourth absorption tower, and a second water seal tank connected in sequence, wherein the third absorption tower is connected to the gas input pipeline and the second water seal tank is connected to the exhaust stack.

[0013] The second water seal tank has multiple functions, including backfire prevention, pressure regulation, pressure stabilization, gas isolation, backflow prevention, and pressure relief protection. Meanwhile, the internal liquid is a 5-10% alkaline solution, which can reabsorb and neutralize any residual silanes or chlorosilanes in the exhaust gas from the fourth absorption tower, ensuring that the exhaust gas is free of silanes and chlorosilanes, thus achieving secondary protection and guaranteeing the complete absorption of silanes or chlorosilanes.

[0014] An emergency chlorosilane discharge port is also provided between the second water seal tank and the exhaust stack.

[0015] Adding an emergency chlorosilane discharge outlet effectively prevents pipeline blockage and reduces safety hazards.

[0016] The chlorosilane tail gas treatment unit includes a first alkaline solution tank and a first sedimentation tank connected in sequence. The first alkaline solution tank is configured to recycle the alkaline solution overflowing from the first sedimentation tank.

[0017] The alkaline solution enters the first sedimentation tank, and after overflowing, it enters the first alkaline solution tank for recycling, which saves resources, avoids waste, and reduces the amount of sewage to be treated.

[0018] The first sedimentation tank is equipped with an alkali overflow outlet with a filter screen at the top.

[0019] A filter screen is installed at the alkaline overflow outlet above the sedimentation tank, which can effectively filter out solid matter and ensure that the upper clear liquid is filtered smoothly and recycled.

[0020] The alkaline solution concentration is between 5% and 10%, and the pH value is between 8 and 10.

[0021] Analysis of the experimental results shows that as the concentration of the alkali solution increases, the alkali washing effect is significantly improved, the reaction is more thorough, and the amount of silane or chlorosilane alkali solution required decreases accordingly. Furthermore, increasing the alkali concentration also reduces the amount of reaction required. The research results indicate that controlling the alkali concentration between 5-10% effectively ensures the alkali washing effect while avoiding the problem of NaCl crystallization.

[0022] Beneficial effects: 1. This application can simultaneously process silanes and chlorosilanes, and the process complies with environmental standards with no pollution emissions. It effectively recovers chlorosilanes, reduces waste, and has a simple and clear process.

[0023] 2. This application adopts a two-stage condensation method to recover chlorosilanes in the chlorosilane emergency handling unit. The operation is simple and pollution-free. The chlorosilane emergency condenser uses circulating water and the chlorosilane emergency cryocooler uses -45 degree refrigerant to ensure refrigeration and condensation effect, fully recover chlorosilanes, and achieve a recovery rate of over 95%.

[0024] 3. The design of the spray mechanism in this application can reduce emissions, improve the completeness of combustion in the combustion tower, and reduce the failure rate of the combustion tower being blocked by particles. Attached Figure Description

[0025] In the attached diagram: Figure 1 A schematic diagram of a silane and chlorosilane waste gas treatment system; Figure 2 This is a schematic diagram of the combustion tower structure; Figure 3 This is a schematic diagram of the structure of a chlorosilane emergency cryostat.

[0026] The components represented by the various reference numerals in the diagram are: 1. First separating tank; 2. Combustion tower; 3. First absorption tower; 4. Second absorption tower; 5. First water seal tank; 6. Exhaust stack; 7. Third absorption tower; 8. Fourth absorption tower; 9. Second water seal tank; 10. Chlorosilane emergency condenser; 11. Chlorosilane emergency cryocooler; 12. Second separating tank; 13. Fifth absorption tower; 14. Sixth absorption tower; 15. Chlorosilane recovery tank; 16. Alkali storage tank; 17. First alkali pool; 18. First sedimentation tank; 19. Second sedimentation tank; 20. Second alkali pool; 21. Slurry pump; 22. Wastewater treatment plant; 23. Silane tail gas primary heater; 24. Silane tail gas secondary heater; 25. Chlorosilane tail gas primary cooler; 26. Chlorosilane tail gas secondary cooler; 27. 28. First circulating pump in a chlorosilane accident; 29. ​​Second circulating pump; 30. Third circulating pump; 31. Fourth circulating pump; 32. Fifth circulating pump; 33. Sixth circulating pump; 34. Spraying mechanism; 35. Ultraviolet detection device; 36. Combustible and toxic gas alarm; 37. Combustion unit; 38. Nitrogen pipeline; 39. Cryogenic inlet; 40. Cryogenic outlet; 41. Refrigerant storage tank; 42. Refrigerant inlet of the chlorosilane accident cryogenic cooler; 43. Refrigerant outlet of the chlorosilane accident cryogenic cooler; 44. First valve; 45. Refrigeration unit; 46. Second valve; 47. Refrigerant vent; 48. Third alkali tank; 49. Third sedimentation tank; 50. Fourth alkali tank; 51. Fourth sedimentation tank. Detailed Implementation

[0027] Example: This embodiment provides a waste gas treatment system for silane and chlorosilane, which is connected to a gas input pipeline and combined with... Figure 1 This includes the silane treatment group and the chlorosilane treatment group. The silane treatment group will be described in detail below with reference to the accompanying drawings.

[0028] In this embodiment, the silane treatment group includes a silane accident treatment unit and a silane tail gas treatment unit.

[0029] The silane accident handling unit includes a first liquid separator 1 and a combustion tower 2 connected to each other, with the first liquid separator 1 connected to a gas input pipeline.

[0030] Specifically, the process for handling a silane accident is as follows: the silane accident emission gas enters the first separating tank 1 through the gas input pipeline for separation. If high-silane liquid is found during the separation process, it is vaporized and then sent to the silane tail gas treatment unit. Other separated silane accident emission gases are divided into three stages according to the emission volume and enter the combustion tower 2 for incineration. Finally, the incinerated gas is discharged from the combustion tower 2.

[0031] The pressure and temperature inside the first separating tank 1 are controlled at atmospheric pressure and ambient temperature; and a remote level gauge is installed on one side of the tank.

[0032] The combustion tower 2 in this application does not contain an ignition system; combustion relies on the self-ignition properties of silane in air.

[0033] Further, see Figure 2 Combustion tower 2 is equipped with a combustion unit 37, which can burn different amounts of gas separated from the first liquid separator 1. A spray mechanism 34 is provided on the top inner side of combustion tower 2. A nitrogen pipeline 38 and a combustion pipeline are also provided on the inner side. The two ends of the nitrogen pipeline 38 are connected to the gas inlet pipeline and the combustion pipeline of combustion tower 2, respectively.

[0034] Nitrogen is used to control the combustion rate, and water mist spraying is used to treat the SiO2 formed after combustion, preventing it from being released into the atmosphere and forming dust, thus achieving spraying and settling and ensuring environmentally friendly combustion. In addition, the system can also absorb residual silane gas, preventing it from being emitted into the atmosphere, reducing environmental pollution and safety hazards.

[0035] Furthermore, an ultraviolet detection device 35 is installed on one side of the combustion tower 2, and a combustible and toxic gas alarm 36 is installed on the other side. The ultraviolet detection device 35 and the combustible and toxic gas alarm 36 can monitor the combustion effect and the content of SiO2 particles and silane in the air in real time to prevent potential problems.

[0036] Combustion tower 2 has a height between 18-30m and a diameter between 8-15m.

[0037] Combustion tower 2 is equipped with 30-45 burners, divided into 3 pressure levels based on pressure differences. The burners are directly exposed to the air, and a spray mechanism 34 is installed above them. Utilizing the chimney effect, it can effectively collect oxygen in the air, thereby promoting a more complete reaction and achieving complete combustion.

[0038] The silane tail gas treatment unit includes a first absorption tower 3, a second absorption tower 4, and a first water seal tank 5 connected in sequence, wherein the first absorption tower 3 is connected to the gas input pipeline.

[0039] Furthermore, the system of this application also includes an exhaust pipe 6, and the first water seal tank 5 is connected to the exhaust pipe 6.

[0040] Specifically, the process for treating silane tail gas is as follows: First, the silane tail gas enters the first absorption tower 3 through the gas input pipeline for alkaline washing treatment, and then enters the second absorption tower 4 for alkaline washing treatment; the treated gas phase passes through the first water seal tank 5 and is finally discharged into the atmosphere through the exhaust stack 6.

[0041] The pressure inside the first absorption tower 3 is controlled at atmospheric pressure, the temperature is controlled at room temperature, the alkaline solution concentration is 10-15% NaOH solution, and the alkaline solution temperature is controlled between 50-70℃.

[0042] Furthermore, the silane tail gas treatment unit also includes a third alkaline solution tank 48, a first circulating pump 28, a silane tail gas primary heater 23 and a third sedimentation tank connected in sequence, wherein the silane tail gas primary heater 23 is connected to the first absorption tower 3.

[0043] The third alkali solution tank 48 is kept at normal pressure and temperature, and is equipped with a stirrer made of carbon steel.

[0044] The third sedimentation tank 49 is also kept at normal temperature and pressure, and has a silane overflow port at the top, which is equipped with a filter device.

[0045] The first circulating pump, 28, is a variable frequency circulating pump. The inlet pressure is controlled at atmospheric pressure, and the inlet temperature is controlled between 25-30℃; the outlet pressure is controlled between 0.25-0.40 MPaG, and the outlet temperature is controlled between 30-40℃; the pump flow rate is controlled between 5-15 m³ / s. 3 Between / h.

[0046] Variable frequency circulating pumps precisely control speed, flow rate, and head by adjusting the motor frequency, meeting dynamic demands without relying on valve throttling and achieving constant pressure liquid supply. Equipped with soft start-stop function, it effectively reduces starting current surges and integrates overvoltage and undervoltage protection mechanisms, significantly improving automation levels. During low-load operation, it reduces energy consumption by lowering the speed, resulting in significant energy savings while also reducing mechanical wear and extending equipment lifespan. It uses a dedicated variable frequency motor and is equipped with an independent cooling fan, optimizing heat dissipation during low-frequency operation and enhancing resistance to high-order harmonic interference. It operates smoothly with minimal mechanical wear, significantly reducing maintenance frequency.

[0047] Furthermore, the tube-side pressure of the silane tail gas primary heater 23 is controlled at atmospheric pressure, the tube-side temperature is controlled at room temperature, and the cooling medium is circulating water.

[0048] Specifically, the alkali solution circulation route is as follows: the first circulation pump 28 extracts the alkali solution from the third alkali solution tank 48, and after being heated by the silane tail gas primary heater 23, it enters the first absorption tower 3 to react with the silane tail gas. After the reaction, the alkali solution flows into the third precipitation tank 49 for solid-liquid separation, and the supernatant overflows back to the third alkali solution tank 48 for recycling.

[0049] The pressure inside the second absorption tower 4 is controlled at atmospheric pressure, the temperature is controlled at room temperature, the alkali solution concentration is 10-15% NaOH solution, and the alkali solution temperature is controlled between 50-70℃.

[0050] Furthermore, the silane tail gas treatment unit also includes a fourth alkaline solution tank 50, a second circulating pump 29, a silane tail gas secondary heater 24, and a fourth sedimentation tank 51 connected in sequence, wherein the silane tail gas secondary heater 24 is connected to the second absorption tower 4.

[0051] The tube-side pressure of the silane tail gas secondary heater 24 is controlled between 1.0-2.5 MPaG, and the tube-side temperature is controlled between 40-70℃; the steam pressure is controlled between 0.40-0.70 MPaG; the heat medium is steam, and the steam temperature is controlled between 120-150℃.

[0052] Specifically, the alkali solution circulation route is as follows: the second circulation pump 29 extracts the alkali solution from the fourth alkali solution tank 50, and after being heated by the silane tail gas secondary heater 24, it enters the second absorption tower 4 to react with the silane tail gas. After the reaction, the alkali solution flows into the fourth precipitation tank 51 for solid-liquid separation, and the supernatant overflows back to the fourth alkali solution tank 50 for recycling.

[0053] The fourth alkali tank 50 has the same internal layout as the third alkali tank 48, and the fourth sedimentation tank 51 has the same internal layout as the third sedimentation tank 49. The second circulation pump 29 is configured the same as the first circulation pump 28.

[0054] The pressure inside the first water seal tank 5 is controlled at atmospheric pressure, and the temperature is controlled at room temperature; the internal solution is a 5-10% NaOH solution. Furthermore, an emergency silane discharge port is added between the vent pipe of the first water seal tank 5 and the exhaust stack 6; the pressure inside the exhaust stack 6 is controlled at atmospheric pressure, the temperature is controlled at room temperature, and the combustion smoke velocity is controlled between 15-30m / s.

[0055] The chlorosilane treatment group includes a chlorosilane accident treatment unit and a chlorosilane tail gas treatment unit.

[0056] The chlorosilane accident handling unit includes a chlorosilane accident condenser 10, a chlorosilane accident cryocooler 11, and a second liquid separator 12 connected to each other, as well as a gas phase recovery unit and a liquid phase recovery unit connected to the second liquid separator 12 respectively, wherein the chlorosilane accident condenser 10 is connected to a gas input pipeline.

[0057] The chlorosilane accident gas enters the silane accident condenser and chlorosilane accident cryostat 11 through the gas input pipeline for condensation. After two-stage condensation, the chlorosilane accident gas enters the second liquid separator 12 for gas-liquid separation. The liquid phase chlorosilane accident gas enters the liquid phase recovery unit, and the gas phase chlorosilane accident gas enters the liquid phase recovery unit.

[0058] The tube-side pressure of the silane emergency condenser is controlled at atmospheric pressure, and the tube-side temperature is controlled at room temperature; the shell-side pressure is controlled between 0.20-0.40 MPaG, and the shell-side temperature is controlled between 25-40℃; the refrigerant is circulating water.

[0059] Next to the chlorosilane emergency cryocooler 11, there is also a refrigerant storage tank 41 connected to it. The tube side pressure of the chlorosilane emergency cryocooler 11 is controlled at atmospheric pressure, and the tube side temperature is controlled at room temperature; the shell side pressure is controlled between 0.00-0.05MPaG, and the shell side temperature is controlled at -45℃. The refrigerant is Freon R507 refrigerant, which is supplied by the refrigerant storage tank 41.

[0060] See Figure 3 The chlorosilane emergency cryocooler 11 is equipped with a refrigeration unit 45, a first valve 44, and a second valve 46. The two ends of the first valve 44 are connected to the refrigerant outlet of the chlorosilane emergency cryocooler 11 and the refrigeration unit 45, respectively. The second valve 46 is connected to the refrigerant outlet of the chlorosilane emergency cryocooler 11 and is designed to drain excess refrigerant, ensuring refrigeration and condensation effects, and fully recovering chlorosilane with a recovery rate of over 95%.

[0061] Furthermore, when the discharge rate of the chlorosilane emergency gas is within the preset range that the chlorosilane emergency cryocooler 11 can withstand, the refrigerant of the chlorosilane emergency cryocooler 11 enters the shell side through the refrigerant inlet 42 to cool the gas entering through the cryocooler inlet 39. After cooling, it is discharged from the cryocooler outlet 40, and the refrigerant is discharged from the refrigerant outlet 43. Then, the first valve 44 is opened to enter the gas phase refrigeration system. When the discharge rate of the chlorosilane emergency gas exceeds the preset range that the chlorosilane emergency cryocooler 11 can withstand, in order to ensure the cryogenic effect, the second valve 46 needs to be opened to allow the excess refrigerant to be discharged through the refrigerant vent 47.

[0062] The second separating tank 12 is controlled at atmospheric pressure and ambient temperature. It has a condenser inlet pipe and a gas outlet pipe at the top, connected to the chlorosilane emergency condenser 10 and the chlorosilane emergency cryostat 11. At the bottom, it has a silicon tetrachloride inlet pipe and a liquid outlet pipe. A certain amount of silicon tetrachloride is introduced into the second separating tank 12 through the silicon tetrachloride inlet pipe. The presence of silicon tetrachloride slows down the flow rate of chlorosilane, prolonging its residence time in the second separating tank 12, thereby improving the separation effect and ensuring complete liquefaction and separation of chlorosilane. The recovered chlorosilane liquid is reused in the production system, while the remaining gas is discharged through the top gas outlet pipe and enters the fifth absorption tower 13.

[0063] The liquid phase recovery unit includes a chlorosilane recovery tank 15. Liquid chlorosilane is discharged from the bottom of the second separator 12 and enters the chlorosilane recovery tank 15 for recovery. Furthermore, the pressure of the chlorosilane recovery tank 15 is controlled at atmospheric pressure and the temperature is controlled at room temperature.

[0064] The gas phase recovery unit includes a fifth absorption tower 13 and a sixth absorption tower 14. Gas phase chlorosilane accident gases sequentially enter the fifth absorption tower 13 and the sixth absorption tower 14 for alkaline washing treatment. The treated, qualified gas is finally discharged into the atmosphere through exhaust stack 6.

[0065] The gas phase recovery unit also includes a first alkali tank 17, a fifth circulating pump 32, and a chlorosilane emergency first-stage cooler 27 connected in sequence. The chlorosilane emergency first-stage cooler 27 is connected to the fifth absorption tower 13. It also includes a first sedimentation tank 18, which is connected to the fifth absorption tower 13.

[0066] The circulation route of the washing alkali solution in the fifth absorption tower 13 is as follows: The fifth circulation pump 32 draws the alkali solution from the first alkali solution tank 17, cools it down through the first-stage cooler 27 in the chlorosilane emergency situation, and then enters the fifth absorption tower 13, where it reacts with the chlorosilane emergency gas to produce sodium chloride and sodium silicate. After the reaction, the liquid flows into the first sedimentation tank 18 for solid-liquid separation, and the supernatant overflows back to the first alkali solution tank 17 for recycling.

[0067] The entire circulation system ensures the removal rate of chlorosilanes and the recycling rate of alkaline solution is >95% through temperature control and pH monitoring, achieving safe and efficient treatment of chlorosilane accident gas.

[0068] Specifically, the pressure inside the fifth absorption tower 13 and the sixth absorption tower 14 is controlled at atmospheric pressure and the temperature is controlled at room temperature.

[0069] The inlet pressure of the fifth circulating pump 32 is controlled at atmospheric pressure, and the inlet temperature is controlled between 25-30℃; the outlet pressure is controlled between 0.50-0.70 MPaG, and the outlet temperature is controlled between 30-40℃; the pump flow rate is controlled between 240-300 m³ / h. 3 Between / h.

[0070] The tube-side pressure of the chlorosilane emergency primary cooler 27 is controlled between 0.50-0.70 MPaG, and the tube-side temperature is controlled between 25-30℃; the shell-side pressure is controlled at atmospheric pressure, and the shell-side temperature is controlled at room temperature; the cooling medium is air. This cooler adopts an air cooler, which has the advantages of low investment, good effect, and strong economy.

[0071] The reaction between chlorosilane gas and alkaline solution is exothermic, as is the reaction between HCl gas and alkaline solution; both reactions release a large amount of heat. According to the principle of chemical equilibrium shift ("upward absorption, downward release"), as the temperature rises, the reaction will proceed in the endothermic direction, leading to a weakening of the reaction effect and a reduction in the alkaline washing effect. To ensure the alkaline washing effect of the fifth absorption tower 13, a chlorosilane emergency primary cooler 27 is added between the first alkaline solution tank 17 and the fifth absorption tower 13 to reduce the temperature of the sprayed alkaline solution, thereby controlling the temperature inside the fifth absorption tower 13 and ensuring the alkaline washing effect.

[0072] The temperature of the fifth absorption tower 13 was controlled between 20-30℃, while the temperature of the sprayed alkaline solution was controlled between 10-20℃. Under the action of the chlorosilane emergency primary cooler 27, the overall temperature of the sprayed alkaline solution and the fifth absorption tower 13 remained stable, approaching room temperature, throughout the reaction process. Sampling and testing of the material at the top of the fifth absorption tower 13 showed that it contained almost no chlorosilane components, indicating a significant alkaline washing effect.

[0073] The gas phase recovery unit also includes a second alkali tank 20, a sixth circulation pump 33, and a second sedimentation tank 19.

[0074] Furthermore, the circulation route of the washing alkaline solution in the sixth absorption tower 14 is as follows: the sixth circulation pump 33 transports the alkaline solution from the second alkaline solution tank 20 to the sixth absorption tower 14, where it undergoes a secondary reaction with the chlorosilane accident gas. After the reaction, it flows into the second precipitation tank 19 for solid-liquid separation, and the supernatant overflows back to the second alkaline solution tank 20.

[0075] This cycle serves as a supplement to the fifth absorption tower 13. It automatically adjusts the pH value to ensure that the final exhaust gas meets emission standards, achieves a high total removal rate of chlorosilanes, and simultaneously realizes the efficient recycling of alkaline solution.

[0076] Specifically, the inlet pressure of the sixth circulating pump 33 is controlled at atmospheric pressure, and the inlet temperature is controlled between 25-30℃; the outlet pressure is controlled between 0.50-0.70 MPaG, and the outlet temperature is controlled between 30-40℃; the pump flow rate is controlled between 240-300 m³ / h. 3 The pump operates between [number] and [number] hours, and uses a variable frequency circulating pump.

[0077] For the chlorosilane emergency gas handling unit, compared with the traditional treatment, a secondary condensation process is added to recover chlorosilanes, which is convenient to operate and pollution-free. The primary condensation uses circulating water, while the secondary condensation uses a -45°C refrigerant to ensure full, efficient and safe recovery of chlorosilanes.

[0078] The chlorosilane tail gas treatment unit includes a third absorption tower 7, a fourth absorption tower 8, and a second water seal tank 9, wherein the third absorption tower 7 is connected to the gas input pipeline.

[0079] The chlorosilane tail gas enters the third absorption tower 7, and then enters the fourth absorption tower 8 for alkaline washing treatment; the qualified gas phase passes through the second water seal tank 9 and is finally discharged into the atmosphere from the exhaust stack 6.

[0080] Furthermore, the pressure inside the second water seal tank 9 is controlled at atmospheric pressure, and the temperature is controlled at room temperature; the internal solution is a 5-10% NaOH solution; an emergency discharge port is added between the vent pipe of the second water seal tank 9 and the exhaust pipe 6.

[0081] The second water seal tank 9 has multiple functions, including backfire prevention, pressure regulation, pressure stabilization, gas isolation, backflow prevention, and pressure relief protection. Simultaneously, the internal liquid is a 5-10% alkaline solution, which can reabsorb and neutralize any residual silanes or chlorosilanes in the exhaust gas from the third absorption tower 7, ensuring that the gas in the exhaust cylinder is free of silanes and chlorosilanes, achieving secondary protection and guaranteeing the complete absorption of silanes or chlorosilanes. An emergency discharge port is added to effectively prevent pipeline blockage and reduce safety hazards.

[0082] The chlorosilane tail gas treatment unit also includes a first alkali pool 17 that works in conjunction with the third absorption tower 7 to complete the first-stage alkali circulation, a third circulation pump 30, a chlorosilane tail gas first-stage cooler 25, and a first sedimentation tank 18.

[0083] Specifically, the circulation route of the washing alkali solution in the third absorption tower 7 is as follows: The third circulation pump 30 draws the alkali solution from the first alkali solution tank 17, cools it through the chlorosilane tail gas primary cooler 25, and then enters the third absorption tower 7, where it undergoes a neutralization reaction with the introduced chlorosilane tail gas. After the reaction, the liquid flows into the first sedimentation tank 18 for solid-liquid separation, and the supernatant overflows back to the first alkali solution tank 17 for recycling, thus completing the circulation process of the first-stage washing alkali solution.

[0084] Furthermore, the pressure inside the first alkali tank 17 is controlled at atmospheric pressure, the temperature is controlled at room temperature, an internal stirrer is installed, the material is CS, the alkali concentration is between 5% and 10%, and the pH value is 8-10.

[0085] The pressure and temperature of the first sedimentation tank 18 are controlled at atmospheric pressure and ambient temperature. An alkali overflow port is opened at the top, and a filter screen device is installed on the overflow port.

[0086] An overflow outlet is provided above the first sedimentation tank 18. When the liquid level in the tank exceeds the overflow outlet, the upper clear liquid will naturally overflow from the alkali overflow outlet and flow into the first alkali tank 17. The filter screen device can effectively filter out colloidal substances, preventing them from clogging the spray pipes and nozzles, ensuring that the upper clear liquid is smoothly filtered into the first alkali tank 17 for recycling. At the same time, alkali is replenished in a timely manner according to the actual alkali concentration in the first alkali tank 17 to maintain the alkali concentration in the tank within a suitable range of 5-10%. The overflow rate of the first sedimentation tank 18 is closely related to the alkali concentration in the first alkali tank 17. By controlling the overflow rate and replenishing alkali in a timely manner, the concentration in the first alkali tank 17 is kept within the normal range.

[0087] The pressure and temperature of the third absorption tower 7 are controlled at atmospheric pressure and ambient temperature.

[0088] The inlet pressure of the third circulation pump 30 is controlled at atmospheric pressure, and the inlet temperature is controlled between 25-30℃; the outlet pressure is controlled between 0.25-0.40 MPaG, and the outlet temperature is controlled between 30-40℃; the pump flow rate is controlled between 5-15 m³ / s.3 Between / h.

[0089] The tube-side pressure of the chlorosilane tail gas primary cooler 25 is controlled between 0.21-0.40 MPaG, and the tube-side temperature is controlled between 30-45℃; the shell-side pressure is controlled between 0.20-0.40 MPaG, and the shell-side temperature is controlled between 25-40℃; the cooling medium is circulating water.

[0090] The chlorosilane tail gas treatment unit also includes a second alkali pool 20 that works in conjunction with the fourth absorption tower 8 to complete a two-stage alkali circulation, a fourth circulation pump 31, a chlorosilane tail gas secondary cooler 26, and a second sedimentation tank 19.

[0091] Specifically, the circulation route of the washing alkali solution in the fourth absorption tower 8 is as follows: The fourth circulation pump 31 draws the alkali solution from the second alkali solution tank 20, cools it through the chlorosilane tail gas secondary cooler 26, and then enters the fourth absorption tower 8, where it undergoes a neutralization reaction with the introduced chlorosilane tail gas. After the reaction, the liquid flows into the second sedimentation tank 19 for solid-liquid separation, and the supernatant overflows back to the second alkali solution tank 20 for recycling, thus completing the circulation process of the secondary washing alkali solution.

[0092] Furthermore, the pressure of the second alkali tank 20 is controlled at atmospheric pressure, the temperature is controlled at room temperature, and it is equipped with a stirrer made of carbon steel.

[0093] The pressure and temperature of the second sedimentation tank 19 are controlled at atmospheric pressure and ambient temperature. An overflow port is opened at the top, and a filter screen device is installed on the overflow port.

[0094] As the precipitate continuously accumulates in the second sedimentation tank 19 and the first sedimentation tank 18, the concentration of NaCl gradually increases. When the NaCl concentration reaches a certain level, NaCl crystals begin to precipitate. The precipitate is then pumped to the wastewater treatment plant 22 for treatment.

[0095] The pressure of the fourth absorption tower 8 is controlled at atmospheric pressure, and the temperature is controlled at room temperature.

[0096] The inlet pressure of the fourth circulating pump 31 is controlled at atmospheric pressure, and the inlet temperature is controlled between 25-30℃; the outlet pressure is controlled between 0.25-0.40MPaG, and the outlet temperature is controlled between 30-40℃; the pump flow rate is controlled between 5-15m3 / h; and a variable frequency circulating pump is used.

[0097] The tube-side pressure of the chlorosilane tail gas secondary cooler 26 is controlled between 0.21-0.40 MPaG, and the tube-side temperature is controlled between 30-45℃; the shell-side pressure is controlled between 0.20-0.40 MPaG, and the shell-side temperature is controlled between 25-40℃; the cooling medium is circulating water.

[0098] In addition, this application also includes an alkali storage tank 16 for storing alkali solution and supplying alkali solution to the first alkali solution tank 17, the second alkali solution tank 20, the third alkali solution tank 48, and the fourth alkali solution tank 50.

[0099] Preferably, this application also includes a mud pump 21 for extracting sediment from the second sedimentation tank 19, the first sedimentation tank 18, the third sedimentation tank 49 and the fourth sedimentation tank 51, and then transporting it to the sewage treatment plant 22 for treatment.

[0100] The entire system of this application is placed in a N2 protective gas environment and adopts a fully sealed design: the system is completely sealed and placed in an N2 environment, effectively isolating air and ensuring safe operation; it significantly improves the exhaust gas treatment effect and further enhances the safety of the system.

[0101] This application eliminates the need for a catalyst, thereby reducing investment costs, saving operating expenses, and eliminating the cumbersome steps and procedures of replacing the catalyst.

Claims

1. A waste gas treatment system for silane and chlorosilane, connected to a gas input pipeline, characterized in that, Includes silane treatment group and chlorosilane treatment group; The silane treatment group includes a silane accident treatment unit and a silane tail gas treatment unit. The silane accident handling unit includes a first liquid separator (1) and a combustion tower (2) connected to each other, wherein the first liquid separator (1) is connected to a gas input pipeline; The combustion tower (2) is equipped with a spraying mechanism (34) on the top of its inner side, and is also equipped with a nitrogen pipeline (38) and a combustion pipeline connected to it. The chlorosilane treatment group includes a chlorosilane accident handling unit and a chlorosilane tail gas treatment unit. The chlorosilane accident handling unit includes a chlorosilane accident condenser (10), a chlorosilane accident cryostat (11), and a second liquid separator (12) connected together, as well as a gas phase recovery unit and a liquid phase recovery unit connected to the second liquid separator (12) respectively, wherein the chlorosilane accident condenser (10) is connected to a gas input pipeline.

2. The waste gas treatment system for silanes and chlorosilanes according to claim 1, characterized in that, The silane tail gas treatment unit, the chlorosilane tail gas treatment unit, and the gas phase recovery unit are all equipped with variable frequency circulating pumps.

3. The waste gas treatment system for silanes and chlorosilanes according to claim 1, characterized in that, The chlorosilane emergency cryostat (11) is equipped with a refrigeration unit (45), a first valve (44) and a second valve (46). The first valve (44) is connected to the refrigerant outlet (47) of the chlorosilane emergency cryostat (11) and the refrigeration unit (45) at both ends, respectively. The second valve (46) is connected to the refrigerant outlet (47) of the chlorosilane emergency cryostat (11) and is configured to drain excess refrigerant.

4. The waste gas treatment system for silanes and chlorosilanes according to claim 1, characterized in that, The chlorosilane tail gas treatment unit also includes an exhaust stack (6) comprising a third absorption tower (7), a fourth absorption tower (8), and a second water seal tank (9) connected in sequence, wherein the third absorption tower (7) is connected to a gas input pipeline and the second water seal tank (9) is connected to the exhaust stack (6).

5. The waste gas treatment system for silanes and chlorosilanes according to claim 4, characterized in that, A chlorosilane emergency discharge port is also provided between the second water seal tank (9) and the exhaust pipe (6).

6. The waste gas treatment system for silanes and chlorosilanes according to claim 1, characterized in that, The chlorosilane tail gas treatment unit includes a first alkaline tank (17) and a first sedimentation tank (18) connected in sequence. The first alkaline tank (17) is configured to recycle the alkaline solution overflowing from the first sedimentation tank (18).

7. The waste gas treatment system for silanes and chlorosilanes according to claim 6, characterized in that, The first sedimentation tank (18) is equipped with an alkali overflow port with a filter screen at the top.

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