An exhaust gas treatment device for a chemical vapor deposition process

Abstract

An exhaust gas treatment device of a chemical vapor deposition process, the outlet of a decontamination device is connected to the inlet of a safety control pipeline, the exhaust gas of the chemical vapor deposition is pretreated in the front stage to remove solid impurities and high-boiling organic matter in the exhaust gas; the outlet of the safety control pipeline is in communication with the inlet of a pressure stabilizing unit, an explosion-proof unit is arranged on the safety control pipeline, including a master control unit, a pressure sensor, a flow measurement module, a gas concentration detector, a flow control valve and a pressure relief valve; when the gas concentration detector detects that the concentration of the dangerous gas exceeds the first gas threshold value, the master control unit adjusts the flow control valve and the pressure relief valve to reduce the exhaust gas conveying rate; the outlet of the pressure stabilizing unit is in communication with an exhaust gas generator, and the output exhaust gas pressure is adjusted to the demand pressure of the exhaust gas generator. The present application realizes the environmental protection treatment and energy recovery of the exhaust gas, prevents blockage through efficient pretreatment, accurately controls safety, matches pressure to improve efficiency, and reduces the production cost of the owner.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and energy recovery technology, and in particular to a tail gas treatment device for a chemical vapor deposition process. Background Technology

[0002] Chemical vapor deposition (CVD) typically uses hydrocarbon or carbon-silicon materials introduced into the process reaction. These materials contain solid impurities such as tar, carbon black dust, silicone oil, silica dust, and vacuum pump oil; high-boiling-point organic compounds such as aromatic hydrocarbons and heterocyclic silanes; and flammable and explosive gases such as hydrogen, methane, ethylene, and acetylene. After high-temperature decomposition in a vacuum furnace, the carbon or silicon is solidified in the product, while the remaining hydrocarbons, silicon, hydrogen, and other substances are discharged outdoors via a vacuum pump.

[0003] Currently, exhaust gases from chemical vapor deposition (CVD) processes are typically treated by flare incineration or direct combustion, which has significant drawbacks: flare incineration is prone to incomplete combustion, resulting in black smoke emissions and tar condensation; while direct combustion can meet emission standards, the recovered steam or hot water will be wasted if the customer does not require it. Furthermore, impurities in the exhaust gas can easily clog pipes, flammable and explosive components pose an explosion risk during transportation, and the exhaust gas pressure is mismatched with the generator set's requirements, affecting energy recovery efficiency.

[0004] Therefore, the existing technology has problems and needs further improvement and development. Summary of the Invention

[0005] (I) Purpose of the invention: In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a tail gas treatment device for chemical vapor deposition process, which aims to solve the problems of pipeline blockage, safety hazards and difficulty in matching the pressure of generator set caused by the complex composition of tail gas, ensure the safe transportation of tail gas and efficient matching with internal combustion generator set, and ultimately realize the environmental protection treatment of tail gas and the reduction of production costs for small and medium-sized production scale owners.

[0006] (II) Technical Solution: In order to solve the above technical problems, this technical solution provides a tail gas treatment device for chemical vapor deposition process, including an anti-clogging purification device, a safety control pipeline, a pressure stabilizing unit and a tail gas generator. The outlet of the anti-clogging purification device is connected to the inlet of the safety control pipeline, the outlet of the safety control pipeline is connected to the inlet of the pressure stabilizing unit, and the outlet of the pressure stabilizing unit is connected to the tail gas generator.

[0007] The anti-clogging purification device is used for pretreatment of chemical vapor deposition tail gas to remove solid impurities and high-boiling-point organic matter that are prone to clogging safety control pipelines in the tail gas.

[0008] The safety control pipeline is equipped with an explosion-proof unit, which includes a main control unit, a pressure sensor, a flow measurement module, a gas concentration detector, a flow control valve, and a pressure relief valve. The pressure sensor, flow measurement module, and gas concentration detector are respectively connected to the main control unit via signal. The flow control valve and pressure relief valve are connected to the main control unit via control. When the gas concentration detector detects that the concentration of hazardous gas exceeds a first gas threshold, the main control unit adjusts the flow control valve and pressure relief valve to reduce the exhaust gas delivery rate.

[0009] The pressure stabilizing unit is used to adjust the exhaust gas pressure output from the safety control pipeline to match the pressure required by the exhaust gas generator.

[0010] Preferably, the anti-clogging purification device includes a vacuum oil mist separator, an explosion-proof high-speed centrifugal oil mist separator, a 0.3μm activated carbon bag filter, and a particulate carbon collector connected in sequence, for sequentially removing vacuum oil fumes, liquid substances, solid impurities, and residual high-boiling-point organic matter.

[0011] Preferably, a two-stage adaptive flow guiding system is further provided between the outlet of the anti-clogging purification device and the inlet of the safety control pipeline, including a first-stage flow guide and a second-stage flow guide; the first-stage flow guide is located at the outlet of the anti-clogging purification device and includes a flow guide plate group, the angle of which is connected to the main control unit via a stepper motor and the adjustment range is between 0° and 45°; the second-stage flow guide is located at the inlet of the safety control pipeline and includes a fixed curved flow guide plate, the curvature of which matches the maximum angle of the first-stage flow guide.

[0012] When the exhaust gas velocity is less than 5 m / s, the main control unit increases the angle of the guide vane to converge the airflow; when the velocity is greater than or equal to 15 m / s, the main control unit decreases the angle of the guide vane to stabilize the exhaust gas velocity entering the safety control pipeline at 8 to 12 m / s.

[0013] Preferably, the safety control pipeline further includes an eddy current system processing unit, which includes an eddy current detection module and an eddy current processing module; the eddy current detection module is used to detect the eddy currents formed by the exhaust gas and their location, and the eddy current processing module is used to eliminate the eddy currents.

[0014] Preferably, the eddy current detection module includes a tracer particle injector and an infrared high-speed camera; the tracer particle injector is located upstream of the safety control pipeline and injects tracer particles into the safety control pipeline; the tracer particles are fluorescent microspheres with a diameter of less than 10 μm;

[0015] The infrared high-speed camera is installed on the inner wall of the safety control pipeline and is connected to the main control unit. It is used to capture the motion trajectory of the tracer particles and output it to the main control unit.

[0016] When a local area of ​​particles is detected to be rotating or its residence time is greater than 2 seconds, the main control unit determines that an eddy current exists and outputs an eddy current position signal; when a local area of ​​particles is detected to be rotating or its residence time is less than or equal to 2 seconds, it determines that no eddy current exists.

[0017] Preferably, the eddy current processing module includes multiple sets of guide vanes and sliding doors. The guide vanes are embedded in the inner wall of the safety control pipe, and the sliding doors are used to cover the guide vanes. When the main control unit determines that there is an eddy current, it controls the corresponding area sliding door to open, so that the guide vanes are exposed and the eddy current is divided into multiple axial branches.

[0018] Preferably, a dynamic pressure sensor is installed on the outer wall of the safety control pipeline along the axial direction at intervals of 1-2 times the pipe diameter. The sampling frequency of the dynamic pressure sensor is greater than or equal to 100Hz, and the dynamic pressure sensor is connected to the main control unit. When a periodic pressure fluctuation of 5-20Hz or a pressure amplitude deviation absolute value greater than 10% of a set threshold is detected, the main control unit determines that there is a pressure pulsation caused by eddy currents.

[0019] Preferably, a pressure fluctuation pre-compensation system is provided between the safety control pipeline and the pressure stabilizing unit, including a high-frequency pressure pulsation sensor and a dynamic pressure buffer chamber;

[0020] The high-frequency pressure pulsation sensor is installed at the outlet of the safety control pipeline to detect high-frequency pressure fluctuations of the exhaust gas in real time; the dynamic pressure buffer chamber is installed at the inlet of the pressure stabilizing unit, and a diaphragm is installed in the dynamic pressure buffer chamber. The diaphragm is driven by a stepper motor to extend and retract, maintaining positive pressure at both ends.

[0021] Preferably, the main control unit is connected to a high-frequency pressure pulsation sensor and a stepper motor signal. It analyzes the frequency and amplitude of high-frequency pressure fluctuations through Fourier transform to predict the pressure peak value entering the pressure stabilization unit in advance. When the predicted pressure peak value exceeds 120% of the design pressure limit of the pressure stabilization unit, it controls the stepper motor to drive the diaphragm to contract into the dynamic pressure buffer chamber. When the pressure fluctuation frequency resonates with the natural frequency of the buffer chamber, it adjusts the diaphragm expansion and contraction frequency to cancel out the phase.

[0022] Preferably, the exhaust gas generator is connected to a steam-water heat exchanger and a catalytic combustion device; the high-temperature flue gas discharged from the internal combustion engine is cooled by the steam-water heat exchanger, and the generated hot water is used for insulation of the safety control pipeline. The cooled flue gas is purified by the catalytic combustion device before being discharged.

[0023] (III) Beneficial Effects: The tail gas treatment device of the chemical vapor deposition process of this invention firstly removes solid impurities and high-boiling-point organic matter from the tail gas through a multi-stage combined pretreatment device, preventing blockage of safety control pipelines and carbon buildup in the generator, thus extending equipment life. Secondly, the entire device is explosion-proof, monitors tail gas composition and flow rate in real time, and dynamically adjusts the tail gas delivery rate through a flow control valve to avoid local concentration exceeding limits; it uses anti-static materials for safety control pipelines to eliminate the risk of static electricity accumulation, ensuring that flammable and explosive tail gas is transported without leakage or exceeding concentration limits. Thirdly, through the cooperation of a buffer tank and a pressure stabilizing unit, the tail gas pressure is stably regulated, avoiding instrument errors caused by negative pressure in the upstream system, ensuring pressure control accuracy, and guaranteeing stable operation of the generator set. Finally, the tail gas is directly sent to the internal combustion generator set for power generation, realizing energy recovery; the high-temperature flue gas discharged from the internal combustion engine is used to heat hot water for insulation of the upstream process safety control pipeline, and the remaining flue gas is discharged after catalytic purification, realizing the cascade utilization of tail gas for power generation, waste heat insulation, and flue gas purification, reducing the owner's production costs and solving the problem of energy waste. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the tail gas treatment device for a chemical vapor deposition process according to the present invention.

[0025] Figure 2 This is an embodiment of the anti-clogging purification device of the present invention;

[0026] Figure 3 This is an embodiment of the voltage regulator unit of the present invention;

[0027] Figure 4 This is an embodiment of the waste heat utilization of the present invention.

[0028] Figure descriptions: 1-Vacuum oil mist separator, 2-Explosion-proof high-speed centrifugal oil mist separator, 3-0.3μm activated carbon bag filter, 4-Particle carbon collector, 5-Roots booster fan, 6-Buffer tank, 7-Internal combustion generator set, 8-Steam-water heat exchanger. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to preferred embodiments. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0030] The accompanying drawings are schematic diagrams of embodiments of the present invention. It should be noted that these drawings are for illustrative purposes only and are not drawn to scale, and should not be construed as limiting the actual scope of protection of the present invention.

[0031] A tail gas treatment device for a chemical vapor deposition process, such as Figures 1-4 As shown, it includes an anti-clogging purification device, a safety control pipeline, a voltage stabilizing unit, and an exhaust gas generator.

[0032] The outlet of the anti-clogging purification device is connected to the inlet of the safety control pipeline, the outlet of the safety control pipeline is connected to the inlet of the pressure stabilizing unit, and the outlet of the pressure stabilizing unit is connected to the exhaust gas generator.

[0033] The anti-clogging purification device employs a multi-stage pretreatment process to pre-treat the exhaust gas from chemical vapor deposition (CVD), removing solid impurities and high-boiling-point organic matter that could easily clog safety control pipes. Specifically, it includes a vacuum oil mist separator 1, an explosion-proof high-speed centrifugal oil mist separator 2, a 0.3μm activated carbon bag filter 3, and a particulate carbon collector 4, connected in sequence. The vacuum oil mist separator, installed at the pump inlet, captures large particles of vacuum oil fumes, carbon black, and tar in the exhaust gas. The explosion-proof high-speed centrifugal oil mist separator separates liquid substances from gases using centrifugal force. The 0.3μm activated carbon bag filter and particulate carbon collector further filter solid impurities and residual high-boiling-point substances. This multi-stage pretreatment process—"oil mist separation → centrifugal liquid removal → multi-stage filtration"—ensures that the exhaust gas entering the generator set is free of clogging impurities, preventing carbon buildup in the generator and extending equipment life.

[0034] The safety control piping consists of straight and curved pipes connected together, adapting to various applications through this interlocking system. The straight pipes are typically positioned before and after the valve assembly, usually five times the pipe diameter before the valve assembly or three times the pipe diameter after it, to ensure fluid stability and prevent flow / pressure fluctuations caused by pipe bends from affecting the valve assembly's measurement accuracy. The curved pipes connect the valve assembly to the pretreatment device and / or buffer tank, and must meet explosion-proof and anti-clogging requirements. Curved pipes may introduce safety risks, such as fluid disturbance affecting monitoring accuracy, impurity deposition leading to blockage or valve jamming, and increased leakage risk due to mechanical wear.

[0035] Specifically, eddies are easily generated at bends in pipes due to fluid deflection. This can lead to instability in gas velocity and pressure in localized areas, potentially causing concentration detectors and pressure sensors within the valve assembly to collect non-uniform gas mixture data, affecting the judgment of actual concentration / pressure. Therefore, optimizing the bend structure to reduce fluid disturbance can be achieved by using bends with a large radius of curvature to reduce centrifugal force during fluid deflection, thus minimizing eddies and velocity fluctuations. Adding guide vanes (such as thin stainless steel sheets) inside the bend can also guide the fluid to flow uniformly and avoid local stagnation. Straight pipes should be prioritized before and after the valve assembly; if bends are necessary, their length should be minimized to reduce interference with valve measurements.

[0036] Solid impurities such as tar and carbon black in exhaust gas tend to deposit at bends in pipes due to reduced flow velocity. Long-term accumulation can clog safety control pipes or enter valve cavities within valve assemblies, causing valve malfunction or sealing failure. Anti-clogging structures can be designed to inhibit impurity deposition. For example, electric or steam heating pipes can be wrapped around bends to maintain the temperature of safety control pipes and prevent tar and high-boiling-point organic matter from condensing and depositing. Regular purging is also crucial: purge ports can be installed at the lowest points of bends to periodically introduce high-pressure nitrogen to flush away deposited carbon black and tar. Selecting valves with self-cleaning functions, such as ball valves, allows the valve seat to automatically scrape off adhering impurities, preventing them from entering the valve cavity and affecting operation.

[0037] Exhaust gas contains hard impurities such as silane and carbon black particles. When flowing through curved pipes, these impurities impact and wear the pipe walls, potentially causing thinning or even rupture of safety control pipes, leading to exhaust gas leaks and, if mixed with air, an explosion. Mechanical safety is enhanced through wear prevention and leak monitoring. For example, tungsten carbide or ceramic coatings are sprayed onto the inner walls of curved pipes to improve wear resistance; combustible gas detectors are installed at flange and valve assembly interfaces of curved pipes to monitor leaks in real time, triggering an alarm when the concentration at the valve assembly interface exceeds a threshold, preferably 1% LEL (Lower Explosive Limit); and ultrasonic thickness gauges are used to periodically inspect curved pipes to promptly detect pipe wall thinning and replace them in a timely manner.

[0038] The safety control pipeline is equipped with an explosion-proof unit, which includes a main control unit, a pressure sensor, a flow measurement module, a gas concentration detector, and a valve assembly. The valve assembly includes a flow control valve and a pressure relief valve. The pressure sensor, flow measurement module, and gas concentration detector are connected to the main control unit via signal connections, and the flow control valve and pressure relief valve are connected to the main control unit via control connections. When the gas concentration detector detects that the concentration of a hazardous gas exceeds a first gas threshold, the main control unit outputs a signal to adjust the flow control valve and pressure relief valve to reduce the exhaust gas delivery rate. The explosion-proof unit ensures that flammable and explosive exhaust gases are delivered without leakage or exceeding concentration limits, thus avoiding safety hazards during exhaust gas delivery.

[0039] The key flammable and explosive gases monitored in the tail gas of chemical vapor deposition (CVD) processes include: hydrogen (H2): accounting for 30%–50%, it is the main combustible component, with an explosion limit of 4%–75% by volume concentration. Hydrocarbon gases: methane (CH4), ethylene (C2H4), acetylene (C2H2), propylene (C3H6), propyne (C3H4), butene (C4H8), etc., are all flammable gases, with lower explosive limits generally below 10%, for example, acetylene's explosion limit is 2.5%–80%. Silane gases: silane (SiH4), unsaturated silane substances (such as Si2H6), etc. Silane's explosion limit is 1.4%–96%, and it is easily ignited in air.

[0040] The flow control valve receives signals from the component sensors in the safety valve assembly and adjusts the opening of the flow control valve and pressure relief valve in real time. If the hydrogen concentration exceeds the explosion threshold, the opening is reduced to decrease the delivery rate and prevent the concentration from exceeding the limit after mixing with air; if the concentration is below the safety threshold, the opening is increased to improve processing efficiency. If the concentration continues to exceed the limit and adjustment is ineffective, the safety valve assembly automatically opens, directing the excess exhaust gas into the exhaust gas generator for safe combustion to prevent further increase in concentration within the safety control pipeline; simultaneously, the explosion-proof shut-off valve is triggered to close, isolating the risk area and preventing the spread of danger.

[0041] The flow control valve needs to be integrated into the explosion-proof valve group to ensure that no sparks are generated during the adjustment process. At the same time, the adjustment strategy is constrained by the safety logic of the system's explosion-proof design. When the concentration exceeds the limit, an emergency valve shut-off procedure should be triggered.

[0042] The safety control pipeline also includes an eddy current system processing unit, which is used to detect and eliminate eddies generated by the exhaust gas. The eddy current system processing unit includes an eddy current detection module and an eddy current processing module.

[0043] Specifically, the eddy current detection module includes a tracer particle injector installed upstream of the safety control pipeline and an infrared high-speed camera installed on the inner wall of the safety control pipeline. The tracer particle injector injects specific tracer particles into the safety control pipeline. By displaying the position of the tracer particles within the safety control pipeline, it can assist in detecting the presence and location of eddies within the safety control pipeline. The tracer particles are fluorescent microspheres with a diameter of less than 10 μm. A micro-nozzle is installed axially along the safety control pipeline. The micro-nozzle is embedded in the pipeline wall or connected by a threaded seal to ensure it is flush with the inner wall and has no protruding structures to reduce eddies. The tracer particle injector achieves axial injection through the micro-nozzle on the pipeline wall, ensuring that the particles are aligned with the mainstream direction of the exhaust gas and avoiding localized eddies that could interfere with the flow field due to vertical injection. Furthermore, the injection flow rate of the tracer particle injector should be strictly controlled to be less than or equal to 0.1% of the exhaust gas volumetric flow rate to prevent excessively high tracer particle concentrations from affecting detection accuracy or clogging downstream equipment.

[0044] The micro-nozzle employs a streamlined, tapering structure to reduce airflow turbulence. Specifically, the inlet diameter is larger to facilitate stable particle entry, while the outlet diameter shrinks to a predetermined value. The outlet of the micro-nozzle is either a flat ellipse or a circle, with a circle being preferred to ensure the axial symmetry of particle injection and avoid localized airflow deflection. If directional particle dispersion is required, a flat ellipse outlet can be used, with the major axis along the radial direction of the pipe to enhance the uniformity of particle distribution across the pipe cross-section. The material of the micro-nozzle must be heat-resistant and corrosion-resistant, with stainless steel or ceramic being preferred.

[0045] According to the conventional safety factor requirements for industrial fluid transportation, in order to avoid blockage, the diameter of the outlet end should be greater than or equal to 5-10 times the diameter of the tracer particles. Therefore, when the tracer particles are fluorescent microspheres with a diameter of less than 10 μm, the minimum diameter of the outlet end should be greater than or equal to 50 μm, preferably 0.1-0.5 mm.

[0046] The infrared high-speed camera is embedded in the inner wall of the safety control pipeline, with its lens facing the same direction as the exhaust flow to ensure coverage of the tracer particle trajectory within the detection area. The infrared high-speed camera is connected to the main control unit via an explosion-proof cable, transmitting tracer particle motion image data in real time. Its sampling frequency is matched to the dynamic pressure sensor to ensure the capture of instantaneous flow velocity changes. The infrared high-speed camera captures the tracer particle trajectory and outputs it to the main control unit. The main control unit can determine the presence and location of eddies based on the specific positions of the tracer particles. The infrared high-speed camera uses a sapphire window flush with the inner wall of the pipeline. The sapphire window is made of a material with high hardness and good light transmittance, and its smooth transition with the pipeline wall avoids protruding structures that could cause airflow disturbance. This meets the requirements for flow field monitoring accuracy and pipeline safety.

[0047] The main control unit, based on the pressure pulsations caused by the eddies, and the infrared high-speed camera capturing the particle trajectory in real time, sends a start signal to the tracer particle injector. When a local area is detected to have particles rotating or having a residence time greater than 2 seconds, it determines that an eddy current exists at that location and outputs an eddy current position signal to the main control unit. When a local area is detected to have particles rotating or having a residence time less than or equal to 2 seconds, it determines that no eddy current exists at that location and that the flow is normal.

[0048] The location of eddies in the safety control pipeline needs to be determined comprehensively based on specific flow conditions and the pipeline structure. The location of eddies includes both stationary and drifting eddies. Stationary eddies occur when the fluid in the pipeline is in a stable flow state, with no significant fluctuations in velocity and pressure, and when the eddies are induced by a fixed structure; in this case, the eddy's location is usually relatively fixed. For example, "secondary flow" eddies downstream of a bend will concentrate in a specific area on the outside of the bend. Separated eddies downstream of valves or throttling devices will stably appear at a fixed axial position after the equipment outlet.

[0049] The drifting vortex, also known as a periodic vortex, occurs under unsteady flow or high Reynolds number turbulent conditions. In such conditions, the vortex position may drift, and even periodic shedding may occur. When the exhaust gas velocity fluctuates, for example, when the main control unit adjusts the flow control valve, the core region of the vortex induced by the original fixed structure will move upstream and downstream with the change in flow velocity. Under high turbulence, random small-scale vortices will form in the flow field, and their position and shape will continuously change. Downstream of a bluff body obstacle, a "Kármán vortex street" may also appear, where vortices will periodically detach from both sides of the obstacle and drift downstream.

[0050] Multiple sets of guide vanes are installed on the inner wall of the safety control duct. These vanes are uniformly spirally embedded in the inner wall of the duct in a circumferential direction. The smooth inner surface of the duct has sliding doors that cover the guide vanes. When the main control unit controls the sliding doors to open based on detected vortices, the guide vanes are exposed on the inner surface of the duct, dividing the rotating airflow of the vortex into multiple streams flowing along the surface of the guide vanes. This disperses the rotational energy of the vortex and forces the exhaust gas to flow axially along the safety control duct. The guide vanes also fill the "low-speed zone" formed by the vortex, applying additional force to the flowing gas within the safety control duct, ensuring balanced gas flow, preventing local flow velocities from falling below 50% of the average velocity, or reverse flow. This stabilizes the flow velocity distribution within the duct within the optimal range of 8–12 m / s, fundamentally suppressing the driving force for vortex maintenance. When the main control unit controls the sliding doors to close, the guide vanes are covered by the sliding doors, and the smooth inner wall of the safety control duct prevents any external influence on the flowing gas.

[0051] The main control unit collects flow velocity data from various detection points within the safety control pipeline in real time. Its acquisition frequency matches the sampling frequency of the dynamic pressure sensors installed on the outer wall of the safety control pipeline, ensuring the capture of instantaneous flow velocity changes. Detection points are evenly distributed along the axial and radial directions of the safety control pipeline. A group of detection points is set at 1-2 times the pipe diameter along the axial direction. Each group includes the center of the safety control pipeline and five radial detection points near the inner wall, comprehensively covering the flow velocity field of the safety control pipeline cross-section.

[0052] When the flow velocity at a certain detection point is lower than 50% of the average flow velocity or reverse flow velocity occurs, the main control unit immediately marks that area as an eddy risk zone. This is because the chemical vapor deposition exhaust gas contains a large amount of solid impurities such as tar and carbon black dust, as well as high-boiling-point organic compounds such as hydrocarbon aromatic hydrocarbons and silicon-hydrogen heterocyclic compounds. Such abnormal flow velocities can cause impurities to deposit in low-velocity areas, gradually leading to blockage of the safety control pipeline. At the same time, reverse flow velocity can cause airflow turbulence, exacerbate the rotational energy of the eddy, and thus generate periodic pressure pulsations, interfering with the measurement accuracy of pressure sensors and gas concentration detectors. It can even increase the explosion risk of flammable and explosive components such as hydrogen and methane due to sudden changes in local pressure.

[0053] After marking the eddy risk area, the main control unit links the location information of this area with the tracer particle injector and the infrared high-speed camera to trigger the tracer particle injection and image capture. The existence of the eddy is verified by the particle motion trajectory. At the same time, combined with the pressure fluctuation data detected by the dynamic pressure sensor, the intensity and range of the eddy are further confirmed. This provides a precise basis for the subsequent control of the sliding door to open the guide vanes in the corresponding area, ensuring that the eddy is eliminated in time and the exhaust gas is stably transported in the optimal flow velocity range of 8-12 m / s, avoiding safety hazards and equipment failures caused by eddy.

[0054] Dynamic pressure sensors are installed along the axial direction on the outer wall of the safety control pipeline at intervals of 1-2 times the pipe diameter. The sampling frequency of the dynamic pressure sensors is greater than or equal to 100Hz, and the dynamic pressure sensors are connected to the main control unit. When a periodic pressure fluctuation of 5-20Hz or a pressure amplitude deviation greater than ±10% of a set threshold is detected, the main control unit determines that there is pressure pulsation caused by eddy currents.

[0055] A two-stage adaptive flow guiding system is installed between the outlet of the anti-clogging purification device and the inlet of the safety control pipeline, including a first-stage flow guide and a second-stage flow guide. The first-stage flow guide is located at the outlet of the anti-clogging purification device and is preferably a variable cross-section flow guide plate assembly. The angle of the flow guide plates can be adjusted by a stepper motor, with an adjustment range between 0° and 45°. The second-stage flow guide is located at the inlet of the safety control pipeline and is preferably a fixed curved surface flow guide plate. The curvature of the curved surface flow guide plate matches the maximum angle of the first-stage flow guide, which is 45°.

[0056] The main control unit is connected to the stepper motor of the first-stage flow guide and monitors the exhaust gas velocity output by the anti-clogging purification device in real time through the flow measurement module. When the flow velocity is less than 5 m / s, the main control unit increases the angle of the flow guide to converge the airflow; when the flow velocity is greater than or equal to 15 m / s, the main control unit decreases the angle of the flow guide to disperse the airflow, thereby stabilizing the exhaust gas velocity entering the safety control pipeline in the optimal range of 8 to 12 m / s.

[0057] The pressure stabilizing unit is located downstream of the safety control pipeline. The pressure stabilizing unit includes a Roots booster blower 5 and a buffer tank 6. It adjusts the exhaust gas pressure output from the safety control pipeline to match the pressure required by the exhaust gas generator. The exhaust gas pressure processed and output by the safety control pipeline is approximately 1000 Pa, and the pressure stabilizing unit uses the Roots booster blower to increase the pressure to over 20 kPa.

[0058] Specifically, the exhaust gas after pretreatment first enters the buffer tank; the Roots blower draws the exhaust gas from the buffer tank and pressurizes it to over 20 kPa; the buffer tank uses a pressure sensor to provide real-time feedback and dynamically adjusts the flow rate matching between the pretreatment unit and the Roots blower. Through the pressure stabilizing effect of the buffer tank, instrument errors caused by negative pressure in the pretreatment system are avoided, ensuring pressure control accuracy and guaranteeing stable operation of the generator set.

[0059] Pressure is monitored by sensors to control valve opening levels, integrated with the UE engine. The UE engine's real-time interface displays data such as buffer tank pressure and flow rate, and performs dynamic simulations to help operators monitor and adjust in real time. More specifically, a "multi-stage buffering + intelligent adjustment" design can be implemented. For example, layered baffles can be added inside the buffer tank to divide the tank space into multiple sub-chambers. Airflow is dispersed step-by-step through small holes in the baffles, reducing the impact of pressure fluctuations on the upstream system. A retractable elastic diaphragm can also be installed inside the buffer tank, automatically adjusting the effective volume according to real-time pressure. When the pressure is too high, the diaphragm expands to increase the volume; when the pressure is too low, it contracts to decrease the volume, improving pressure stabilization. Alternatively, multi-parameter sensors for temperature, humidity, and pressure can be integrated into the buffer tank to not only monitor pressure but also help determine the exhaust gas status and assess the risk of condensation.

[0060] A pressure fluctuation pre-compensation system is installed between the safety control pipeline and the pressure stabilizing unit. The pressure fluctuation pre-compensation system includes a high-frequency pressure pulsation sensor and a dynamic pressure buffer chamber.

[0061] Specifically, the high-frequency pressure pulsation sensor is installed at the outlet of the safety control pipeline to monitor the high-frequency pressure fluctuations of the exhaust gas in real time; the dynamic pressure buffer chamber is installed at the inlet of the pressure stabilizing unit, and a retractable diaphragm is installed in the dynamic pressure buffer chamber. The expansion and contraction displacement of the retractable diaphragm is driven by a stepper motor to maintain positive pressure at the front and back, and to avoid negative pressure affecting the measurement accuracy of the instrument.

[0062] The main control unit is connected to a high-frequency pressure pulsation sensor and a stepper motor signal. It analyzes the frequency and amplitude of high-frequency pressure fluctuations through Fourier transform to predict the pressure peak value entering the voltage stabilization unit in advance. When the predicted pressure peak value exceeds 120% of the design pressure limit of the voltage stabilization unit, it controls the stepper motor to drive the diaphragm to contract into the buffer chamber to absorb some of the pressure energy. When the pressure fluctuation frequency resonates with the natural frequency of the buffer chamber, it adjusts the diaphragm expansion and contraction frequency to cancel out the phase and reduce the pressure regulation load of the voltage stabilization unit.

[0063] The pretreated exhaust gas is pressurized and then fed into an internal combustion generator set 7 for combustion and power generation. The electricity is then directly input into the owner's low-voltage switchgear after voltage transformation and frequency regulation. The high-temperature flue gas discharged from the internal combustion engine is cooled to 450℃ through a steam-water heat exchanger 8. The hot water is used for insulation of upstream process safety control pipelines, and the remaining flue gas is purified by catalytic combustion before being discharged. This achieves a cascade utilization of "exhaust gas power generation → waste heat insulation → flue gas purification," which not only solves environmental problems but also reduces the owner's production costs through electricity recovery.

[0064] Specifically, the implementation of this invention is divided into four stages:

[0065] S1: Pre-processing stage.

[0066] The exhaust gas from chemical vapor deposition (CVD) is highly complex, containing numerous solid impurities, including but not limited to tar, carbon black dust, silicone oil, silica dust, and vacuum pump oil. It also contains complex hydrocarbon aromatics and silicon-hydrogen heterocyclic compounds with high boiling points, which easily condense in the pipeline, causing blockages. Therefore, appropriate technologies must be used upstream to remove impurities and high-boiling-point substances from the exhaust gas to prevent blockages in the delivery pipeline and carbon buildup in the internal combustion engine.

[0067] This invention employs a combination of four methods—vacuum oil mist filter, high-speed centrifugal separator, activated carbon bag filter, and activated carbon adsorber—for pre-treatment of exhaust gas. After being discharged from the vacuum pump, the exhaust gas first passes through a vacuum oil mist separator installed at the pump inlet, capturing large particles of vacuum oil fumes, carbon black, and tar. Then, through two control valves, the exhaust gas is transported to an outdoor explosion-proof high-speed centrifugal oil mist separator, where centrifugal force separates the liquid substances from the gas. The separated gas then passes sequentially through a 0.3μm activated carbon bag filter and a particulate carbon collector for further filtration of solid impurities and residual high-boiling-point substances, resulting in preliminarily purified exhaust gas.

[0068] S2: Safe transport phase.

[0069] Chemical vapor deposition exhaust contains a large amount of hydrogen (30% to 50%), as well as a large amount of flammable and explosive hydrocarbons (methane, ethylene, acetylene, propylene, propyne, butene) and silanes (silanes, unsaturated silanes). These components can cause violent combustion or explosion when exposed to static electricity or open flame in the presence of oxygen.

[0070] The purified exhaust gas enters a safety control pipeline, where an explosion-proof unit monitors the pressure, flow rate, and gas concentration in real time. When the gas concentration detector detects that the concentration of hazardous gas exceeds the threshold, the main control unit controls the flow control valve and pressure relief valve to reduce the exhaust gas delivery rate. Simultaneously, eddies are detected using devices such as a dynamic pressure sensor, a tracer particle injector, and an infrared high-speed camera. When eddies are detected, the main control unit controls the sliding door to open, exposing the guide vanes on the inner wall to eliminate the eddies. The two-stage adaptive flow guidance system automatically adjusts the angle of the guide vanes according to the exhaust gas velocity, ensuring that the exhaust gas velocity entering the safety control pipeline remains stable within the optimal range.

[0071] S3: Pressure matching phase.

[0072] Matching the pressure control of the internal combustion generator set, the exhaust gas pressure after pretreatment is around 1000 Pa, while the generator set requires a pressure of 20 kPa. A Roots booster blower is then installed for further pressurization. During the pressurization process, the pretreatment stage can easily be drawn into a negative pressure state. Excessive negative pressure can cause errors in the measurement accuracy of the instruments on the safety control valve assembly.

[0073] The exhaust gas from the safety control pipeline enters the pressure stabilizing unit. A high-frequency pressure pulsation sensor detects high-frequency pressure fluctuations in the exhaust gas in real time. The dynamic pressure buffer chamber absorbs pressure energy or cancels it out with an anti-phase effect through a stretchable diaphragm, reducing the pressure regulation load on the pressure stabilizing unit. The Roots booster blower increases the exhaust gas pressure from approximately 1000 Pa to over 20 kPa, while the buffer tank maintains positive pressure before and after, ensuring pressure stability.

[0074] S4: Exhaust gas power generation and waste heat utilization stage.

[0075] The pressurized exhaust gas is fed into the internal combustion generator set, where it is combusted at high temperature in the engine chamber, driving the generator rotor to generate electricity. The electricity is then input to the owner's low-voltage switchgear after being transformed and regulated by frequency converter. The high-temperature flue gas of about 500°C discharged from the internal combustion engine is cooled to 450°C through a steam-water heat exchanger. The resulting hot water is used for insulation of upstream process safety control pipelines. After being purified by catalytic combustion equipment, the cooled flue gas is discharged through the chimney in compliance with emission standards.

[0076] This invention discloses a tail gas treatment device for a chemical vapor deposition process. First, a multi-stage pretreatment unit effectively removes solid impurities and high-boiling-point organic compounds from the tail gas, preventing blockage of safety control pipelines and carbon buildup in the generator, thus extending equipment lifespan. Second, the entire device features an explosion-proof design, real-time monitoring of tail gas composition and flow rate, and dynamic adjustment of the tail gas delivery rate via a flow control valve to avoid local concentration exceeding limits. Anti-static materials are used in the safety control pipelines to eliminate the risk of static electricity accumulation, ensuring no leakage or concentration exceeding limits during the delivery of flammable and explosive tail gas. Third, the cooperation of a buffer tank and a pressure stabilizing unit achieves stable tail gas pressure regulation, avoiding instrument errors caused by negative pressure in the upstream system, ensuring pressure control accuracy, and guaranteeing stable generator operation. Finally, the tail gas is directly fed into an internal combustion engine generator set for power generation, achieving energy recovery. The high-temperature flue gas from the internal combustion engine heats hot water for insulation of the upstream process safety control pipelines, and the remaining flue gas is discharged after catalytic purification, realizing the cascade utilization of "tail gas power generation, waste heat insulation, and flue gas purification," reducing the owner's production costs and solving the problem of energy waste.

[0077] In summary, the exhaust gas treatment device of the present invention, based on chemical vapor deposition process, achieves environmental protection treatment and energy recovery of exhaust gas. Through efficient pretreatment to prevent clogging, precise control to ensure safety, and pressure matching to improve efficiency, it reduces the owner's production costs.

[0078] The above description illustrates preferred embodiments of the present invention and helps those skilled in the art to more fully understand the technical solution of the present invention. However, these embodiments are merely illustrative and should not be construed as limiting the specific implementation of the present invention to these embodiments. For those skilled in the art, several simple deductions and modifications can be made without departing from the inventive concept, and all such modifications should be considered within the protection scope of the present invention.

Claims

1. A tail gas treatment device for a chemical vapor deposition process, comprising an anti-clogging purification device, a safety control pipeline, a voltage stabilizing unit, and a tail gas generator, characterized in that, The outlet of the anti-clogging purification device is connected to the inlet of the safety control pipeline, the outlet of the safety control pipeline is connected to the inlet of the pressure stabilizing unit, and the outlet of the pressure stabilizing unit is connected to the exhaust gas generator. The anti-clogging purification device is used for pretreatment of chemical vapor deposition tail gas to remove solid impurities and high-boiling-point organic matter that are prone to clogging safety control pipelines in the tail gas. The safety control pipeline is equipped with an explosion-proof unit and an eddy current system processing unit. The explosion-proof unit includes a main control unit, a pressure sensor, a flow measurement module, a gas concentration detector, a flow control valve, and a pressure relief valve. The pressure sensor, flow measurement module, and gas concentration detector are respectively connected to the main control unit via signal. The flow control valve and pressure relief valve are controlled by the main control unit. When the gas concentration detector detects that the concentration of hazardous gas exceeds a first gas threshold, the main control unit adjusts the flow control valve and pressure relief valve to reduce the exhaust gas delivery rate. The eddy current system processing unit includes an eddy current detection module and an eddy current processing module. The eddy current detection module is used to detect the eddies formed by the exhaust gas and their location. The eddy current processing module is used to eliminate eddies and includes multiple sets of guide vanes and sliding doors. The guide vanes are uniformly embedded in the inner wall of the safety control pipeline, and the sliding doors are used to cover the guide vanes. When the main control unit determines that eddies exist, it controls the corresponding area's sliding door to open, exposing the guide vanes and dividing the eddy current into multiple axial branches. The pressure stabilizing unit is used to adjust the exhaust gas pressure output from the safety control pipeline to match the pressure required by the exhaust gas generator. A pressure fluctuation pre-compensation system is set between the safety control pipeline and the pressure stabilizing unit. The pressure fluctuation pre-compensation system includes a high-frequency pressure pulsation sensor and a dynamic pressure buffer chamber. By analyzing the frequency and amplitude of the high-frequency pressure fluctuation through Fourier transform, the pressure peak value entering the pressure stabilizing unit can be predicted in advance.

2. The tail gas treatment device for a chemical vapor deposition process according to claim 1, characterized in that, The anti-clogging purification device includes a vacuum oil mist separator, an explosion-proof high-speed centrifugal oil mist separator, a 0.3μm activated carbon bag filter, and a particulate carbon collector connected in sequence, which are used to remove vacuum oil fumes, liquid substances, solid impurities, and residual high-boiling-point organic matter in sequence.

3. The tail gas treatment device for a chemical vapor deposition process according to claim 1, characterized in that, A two-stage adaptive flow guiding system is also provided between the outlet of the anti-clogging purification device and the inlet of the safety control pipeline, including a first-stage flow guide and a second-stage flow guide. The first-stage flow guide is located at the outlet of the anti-clogging purification device and includes a flow guide plate group. The angle of the flow guide plate is connected to the main control unit via a stepper motor, and the adjustment range is between 0° and 45°. The second-stage flow guide is located at the inlet of the safety control pipeline and includes a fixed curved flow guide plate. The curvature of the curved flow guide plate matches the maximum angle of the first-stage flow guide. When the exhaust gas velocity is less than 5 m / s, the main control unit increases the angle of the guide vane to converge the airflow; when the velocity is greater than or equal to 15 m / s, the main control unit decreases the angle of the guide vane to stabilize the exhaust gas velocity entering the safety control pipeline at 8 to 12 m / s.

4. The tail gas treatment device for a chemical vapor deposition process according to claim 1, characterized in that, The eddy current detection module includes a tracer particle injector and an infrared high-speed camera; the tracer particle injector is located upstream of the safety control pipeline and injects tracer particles into the safety control pipeline; the tracer particles are fluorescent microspheres with a diameter of less than 10 μm; The infrared high-speed camera is installed on the inner wall of the safety control pipeline and is connected to the main control unit. It is used to capture the motion trajectory of the tracer particles and output it to the main control unit. When a local area of ​​particles is detected to be rotating or its residence time is greater than 2 seconds, the main control unit determines that an eddy current exists and outputs an eddy current position signal; when a local area of ​​particles is detected to be rotating or its residence time is less than or equal to 2 seconds, it determines that no eddy current exists.

5. The tail gas treatment device for a chemical vapor deposition process according to claim 1, characterized in that, Dynamic pressure sensors are installed on the outer wall of the safety control pipeline at axial intervals of 1-2 times the pipe diameter. The sampling frequency of the dynamic pressure sensors is greater than or equal to 100Hz, and the dynamic pressure sensors are connected to the main control unit. When a periodic pressure fluctuation of 5-20Hz or a pressure amplitude deviation absolute value greater than 10% of the set threshold is detected, the main control unit determines that there is pressure pulsation caused by eddy currents.

6. The tail gas treatment device for a chemical vapor deposition process according to claim 1, characterized in that, The high-frequency pressure pulsation sensor is installed at the outlet of the safety control pipeline to detect high-frequency pressure fluctuations of the exhaust gas in real time; the dynamic pressure buffer chamber is installed at the inlet of the pressure stabilizing unit, and a diaphragm is installed in the dynamic pressure buffer chamber. The diaphragm is driven by a stepper motor to extend and retract, maintaining positive pressure at both ends.

7. The tail gas treatment device for a chemical vapor deposition process according to claim 6, characterized in that, When the predicted pressure peak exceeds 120% of the design pressure limit of the pressure stabilizing unit, the stepper motor is controlled to drive the diaphragm to contract into the dynamic pressure buffer chamber; when the pressure fluctuation frequency resonates with the natural frequency of the buffer chamber, the diaphragm extension and contraction frequency is adjusted to cancel out the phase.

8. The tail gas treatment device for a chemical vapor deposition process according to claim 1, characterized in that, The exhaust gas generator is connected to a steam-water heat exchanger and a catalytic combustion device; the high-temperature flue gas discharged from the internal combustion engine is cooled by the steam-water heat exchanger, and the generated hot water is used for insulation of the safety control pipeline. The cooled flue gas is then purified by the catalytic combustion device before being discharged.

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