A submicron particle removal device

Abstract

The present application relates to a kind of submicron particle removal devices, including gas injection and mixing section, cooling section, condensation growth chamber and inertial impact separator connected in sequence;Gas injection and mixing section is equipped with air inlet and water vapor inlet, the air containing submicron particles from air inlet, water vapor inlet inputs water vapor, water vapor and air are mixed;Cooling section is equipped with heat exchange structure, condensation growth chamber is equipped with rectifier and guide vane;Inertial impact separator is equipped with exhaust passage and guide groove, the air after submicron particle removal is discharged through exhaust passage, and condensate is discharged through guide groove.Compared with prior art, the present application has the advantage of using supersaturation formation mode after mixing, which avoids the problem of traditional high-flow cooling device prone to condensation on the wall;Submicron particles grow rapidly after condensation growth chamber, which improves the efficiency of inertial impact separation.

Description

Technical Field

[0001] This invention relates to suspended particulate matter, and more particularly to a submicron particle removal device. Background Technology

[0002] As semiconductor chip sizes continue to shrink, the requirements for controlling airborne particulate matter in clean environments are becoming increasingly stringent, especially for submicron particles with a diameter of less than 300 nm. These particles are lightweight and exhibit significant Brownian diffusion, making them difficult to remove through inertial settling or gravity capture. However, even trace amounts entering the process area can lead to device defects and reduced yield.

[0003] Currently used air purification technologies include: 1. HEPA / ULPA high-efficiency filtration. High-efficiency filters capture suspended particles through fiber interception, diffusion, and inertial effects. They have extremely high efficiency for particles ≥0.3μm in diameter, but the penetration rate increases significantly for particles smaller than 100nm. To meet higher cleanliness requirements, multi-stage filtration or increased filtration area is often required, which leads to increased system pressure drop, higher fan energy consumption, and more frequent maintenance. 2. Electrostatic precipitators and wet scrubbing. Electrostatic precipitators use an electric field to charge particles and adsorb them onto the collecting plates, while wet scrubbing removes particles through collision or dissolution of droplets. These methods are widely used in air pollution control, but they have shortcomings in cleanroom settings: electrostatic methods easily generate ozone or byproducts, and wet methods increase air humidity and may introduce impurities, both of which are difficult to meet the dryness and chemical cleanliness requirements of semiconductor processes. 3. Condensation growth technology. The condensation growth method introduces saturated or supersaturated vapor into a dust-laden airflow, causing nanoscale particles to grow into micron-sized droplets, which are then removed using conventional filtration or inertial separation. This principle has been widely used in instruments such as condensation nucleus particle counters (CPCs) for detecting submicron particles. However, existing condensation growth devices are mainly designed for low-flow-rate applications. Directly applying them to high-volume cleanroom ventilation systems presents several problems: uneven distribution of the supersaturated zone, leading to condensation on the walls and secondary droplet release; and significant engineering challenges, with increased pressure drop and energy consumption likely after increasing the flow rate.

[0004] A search revealed that application publication number CN107029510A discloses an air purification device utilizing condensation growth. Specifically, this device includes an air saturator that utilizes water spray or the evaporation of water through a porous membrane, a condenser that causes particle growth by condensing water vapor, and a removal machine, thereby removing ultrafine dust under high flow / high concentration conditions. This prior art creates supersaturation through a saturator and condenser or adiabatic expansion cooling method, resulting in a complex design and a tendency for wall condensation.

[0005] In summary, while existing technologies can remove particles to a certain extent, they are difficult to balance efficient removal of submicron particles with low pressure drop operation. Therefore, a new device is urgently needed to improve this technology. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art, which cannot simultaneously satisfy the requirements of submicron particle removal and low-pressure drop operation, and to provide a submicron particle removal device.

[0007] The objective of this invention can be achieved through the following technical solutions.

[0008] According to one aspect of the present invention, a submicron particle removal device is provided, comprising a gas injection and mixing section, a cooling section, a condensation growth chamber, and an inertial impact separator connected in sequence; the gas injection and mixing section is provided with an air inlet and a water vapor inlet, the air entering from the air inlet contains submicron particles, and the water vapor inlet introduces water vapor, which mixes with the air; the cooling section is provided with a heat exchange structure, and the condensation growth chamber is provided with rectifier plates and guide plates; the inertial impact separator is provided with a guide channel, a slit nozzle, and an impact collection plate, the slit nozzle is connected to the condensation growth chamber, and an exhaust channel is formed between the slit nozzle and the impact collection plate, the air after submicron particle removal is discharged through the exhaust channel, and the condensate is discharged through the guide channel.

[0009] As a preferred technical solution, the device also includes a steam generator, which is connected to the water inlet of the gas injection and mixing section via a venturi tube or a multi-point tangential injector. The steam generator produces pure water steam at 60~80°C.

[0010] As a preferred technical solution, the heat exchange structure is a jacketed heat exchanger or a coil heat exchanger, and the temperature of the cooling medium inside the heat exchange structure is 4~5℃.

[0011] As a preferred technical solution, submicron particles are grown into droplets of 1~5μm in the condensation growth chamber.

[0012] As a preferred technical solution, the inertial impact separator includes a slit nozzle and an impact collection plate. The slit nozzle is connected to a condensation growth chamber. An exhaust channel is formed between the slit nozzle and the impact collection plate. The exhaust channel is a bendable exhaust channel. The guide channel is located on the side of the impact collection plate near the ground. The guide channel has a slope towards the ground. A one-way drain valve and a collection chamber are installed at the end of the guide channel in sequence.

[0013] As a preferred technical solution, the angle of the curved exhaust channel is less than or equal to 90°.

[0014] As a preferred technical solution, the impact collection plate has a drawer-type structure and a hydrophilic coating on its surface.

[0015] As a preferred technical solution, the device further includes a secondary dehumidification module and a reheat module. The secondary dehumidification module is connected to the exhaust channel, and the reheat module is connected to the secondary dehumidification module. The secondary dehumidification module includes a low-temperature condensation unit or a membrane dehumidification unit.

[0016] As a preferred technical solution, the dew point of the air discharged from the secondary dehumidification module and the reheat module is less than or equal to 15°C.

[0017] As a preferred technical solution, the device further includes a monitoring and control module, which includes a programmable controller and temperature sensors, humidity sensors, dew point sensors, differential pressure sensors, flow sensors and particle counting sensors connected to the programmable controller. The temperature sensor and humidity sensor are installed in the gas injection and mixing section, cooling section and exhaust channel; the dew point sensor is installed in the exhaust channel; the differential pressure sensor, flow sensor and particle counting sensor are installed in the water vapor inlet and exhaust channel.

[0018] Compared with the prior art, the present invention has the following beneficial effects.

[0019] 1) This invention employs a pre-mixing followed by cooling method to form supersaturation. Water vapor is first uniformly injected into and mixed in the mixing section before entering the cooling section to form supersaturation in the central region, avoiding the condensation problem on the walls of traditional high-flow-rate cooling devices. Submicron particles grow rapidly after passing through the condensation growth chamber, improving the efficiency of inertial impaction separation. The rectifier and guide vanes maintain a stable flow field and ensure uniform supersaturation distribution. Air is accelerated through the slit nozzle, resulting in a pressure drop, allowing the device to operate under low pressure.

[0020] 2) The steam generator of the present invention is connected to a venturi tube or a multi-point tangential injector to the water inlet of the gas injection and mixing section, so as to inject water vapor evenly into the air and ensure that the water vapor and the dust-laden airflow are fully mixed.

[0021] 3) The present invention features a large temperature difference between the cooling medium and the mixed gas (water vapor and air containing submicron particles) within the heat exchange structure. This causes the mixed gas to cool rapidly within the heat exchange structure, creating a supersaturated environment in the central region. This suppresses condensation on the wall surface and preferentially promotes the growth of submicron particles as condensation nuclei into droplets. The steam generator produces pure water vapor at 60-80°C, while the cooling medium temperature within the heat exchange structure is 4-5°C. This ensures a large temperature difference, thereby guaranteeing a large water-gas pressure difference, facilitating the processing of submicron particles. Furthermore, it prevents excessive water vapor volume from increasing the difficulty of dehumidification at the outlet.

[0022] 4) This invention forms a bend in the exhaust channel between the slit nozzle and the impact collection plate. The airflow accelerates through the slit nozzle and then sharply turns at the bend in the exhaust channel. The droplets, due to their higher Stokes number, deviate from the main trajectory and are captured by the impact collection plate, thus achieving solid-liquid separation. The impact collection plate has a sloping guide channel and a one-way drain valve below it, facilitating timely discharge of condensate and preventing secondary carryover. The collection chamber is used to collect waste liquid generated by the system; the collected waste liquid can be used for subsequent analysis of the composition of airborne particulate matter or for centralized treatment.

[0023] 5) The two-stage dehumidification module and reheat module of this invention reduce the dew point of the airflow from the positive temperature range reached after steam injection to ≤-15℃, or even ≤-20℃, taking into account both particle removal and the low humidity requirements of cleanrooms; it is more suitable for semiconductor process environments than traditional wet collection methods, avoiding process defects caused by excessive air humidity.

[0024] 6) This invention uses a monitoring and control module to adjust the steam injection rate, cooling water flow rate, and reheat module power, thereby achieving fully automatic control of the process. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of a submicron particle removal device according to the present invention.

[0026] Figure 2 This is a schematic diagram of the gas injection and mixing section and the cooling section of the present invention.

[0027] Figure 3 This is a partial structural schematic diagram of the inertial impact separator of the present invention.

[0028] The numbers in the diagram are as follows: 1. Gas injection and mixing section; 10. Air inlet; 11. Water and gas inlet; 2. Cooling section; 20. Jacketed heat exchanger; 200. Cooling water inlet; 201. Cooling water outlet; 21. Multi-point tangential injector; 22. Insulation layer; 3. Condensation growth chamber; 4. Inertial impact separator; 40. Exhaust channel; 41. Guide channel; 42. Slit nozzle; 43. Impact collection plate; 44. One-way drain valve. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0030] like Figure 1As shown, the present invention provides a submicron particle removal device, comprising a gas injection and mixing section 1, a cooling section 2, a condensation growth chamber 3, an inertial impact separator 4, a secondary dehumidification module, and a reheat module connected in sequence, the above parts being connected to form an integrated airflow passage; the device also includes a steam generator and a monitoring and control module.

[0031] like Figure 2 As shown, the gas injection and mixing section 1 is equipped with an air inlet 10 and a water vapor inlet 11. The air inlet 10 is connected to the cleanroom return air or supply air duct to introduce air containing submicron particles into the device. The steam generator is connected to the water vapor inlet 11 of the gas injection and mixing section 1 through a venturi tube or a multi-point tangential injector 21. The steam generator produces pure water vapor at 60~80℃ and injects the water vapor evenly into the main airflow (air containing submicron particles) through the venturi tube or the multi-point tangential injector 21 to ensure that the water vapor and the dust-laden airflow are fully mixed.

[0032] The cooling section 2 is equipped with a heat exchange structure, which can be a jacketed heat exchanger 20 or a coiled heat exchanger. The temperature of the cooling medium inside the heat exchange structure is 4~5℃, and the cooling medium can be cooling water. When a jacketed heat exchanger 20 is used, the jacketed heat exchanger 20 has a cooling water inlet 200 and a cooling water outlet 201 on both sides, and is externally covered with an insulation layer 22. The airflow is rapidly cooled in the cooling section 2, forming a supersaturated environment in the central area, thereby inhibiting condensation on the wall surface and preferentially promoting the growth of particulate matter as condensation nuclei into droplets.

[0033] The condensation growth chamber 3 is equipped with rectifiers and guide vanes to maintain a stable flow field and ensure uniform supersaturation distribution. Submicron particles grow into droplets of 1~5μm within this section.

[0034] like Figure 3As shown, the inertial impact separator 4 includes a slit nozzle 42 and an impact collection plate 43. One end of the slit nozzle 42 is connected to the condensation growth chamber 3, and the other end is fitted with the impact collection plate 43. A bend exhaust channel 40 is formed between the slit nozzle 42 and the impact collection plate 43, with an angle of less than or equal to 90°. The impact collection plate 43 has a drawer-type structure with a hydrophilic coating on its surface, allowing it to be pulled out. Periodic high-temperature steam or pure water rinsing ensures long-term stable operation. The size of the slit nozzle 42 determines the pressure drop of the device. The slit nozzle 42 can be achieved by setting multiple flow-limiting orifices of the same size on a plate. When the airflow passes through the flow-limiting orifices, it is accelerated, resulting in a pressure drop. By increasing the number of flow-limiting orifices, the system can operate under low pressure drop. The impact collection plate 43 has a guide channel 41 on the side closest to the ground. The guide channel 41 has a slope towards the ground, and a one-way drain valve 44 is installed at the end of the guide channel 41. After being captured, the liquid droplets are discharged through the guide channel 41. After being accelerated through the slit nozzle 42, the airflow makes a sharp turn at the bend in the curved exhaust channel 40. Due to its higher Stokes number, the droplets deviate from the main trajectory and are captured by the impact collection plate 43, thus achieving the separation of submicron particles from the gas. A liquid seal is installed on the guide channel 41 to prevent gas from leaving. An automatic drain valve can drain some liquid when it accumulates to a certain height. A bypass design allows manual opening of the valve in case of malfunction. The impact collection plate 43, combined with the automatic drain valve and bypass design, eliminates the need for a complete shutdown during maintenance, reducing downtime losses.

[0035] The secondary dehumidification module is connected to the exhaust channel 40, and the reheat module is connected to the secondary dehumidification module. The secondary dehumidification module includes a low-temperature condensation unit or a membrane dehumidification unit. After inertial separation, the secondary dehumidification module is set up in conjunction with the reheat module to remove residual moisture in the airflow, so that the outlet dew point is controlled at ≤-15℃, ensuring that the air dryness meets the requirements of semiconductor process.

[0036] The monitoring and control module includes a programmable controller, temperature sensor, humidity sensor, dew point sensor, differential pressure sensor, flow sensor, and particle counting sensor. The monitoring and control module monitors the operating status in real time, and the programmable controller adjusts the steam injection rate, cooling water flow rate, and reheat power to achieve closed-loop control of the entire process.

[0037] The working process of this invention is as follows: 1) Air containing submicron particles is mixed with water vapor and then enters the condensation growth chamber 3 through the cooling section 2; 2) In the condensation growth chamber 3, particles with a diameter of less than 300 nm grow to 1~5 μm droplets through heterogeneous condensation; 3) The droplets enter the slit nozzle 42 at high speed with the airflow and make a sharp turn. Due to inertia, they collide with the impact collection plate 43 and are captured. 4) The collected condensate is discharged through the guide channel 41; 5) The airflow continues to pass through the secondary dehumidification module to remove residual moisture, and then is restored to a suitable temperature through the reheat module; 6) The outlet airflow is monitored by a dew point sensor and a particle count sensor to ensure that both the particle count and dew point meet the cleanroom standards.

[0038] The parameter setting ranges during the operation of this invention are shown in Table 1.

[0039] Table 1. Parameter Settings for Submicron Particle Removal Process The following is an example of quick verification and size estimation: 1) Flow conversion: Q = 3000 m3 / h = 0.833 m3 / s; if the target wind speed U ≈ 12 m / s, then the cross-sectional area A ≈ 0.0694 m2, and the equivalent circular pipe diameter D ≈ 297 mm (DN300 or rectangular equivalent pipe can be used in engineering).

[0040] 2) Inertial separation Stokes number: Stk = ρ•d²•U / (18μD). When U = 15 m / s and D = 3 mm, d = 2 μm → Stk ≈ 0.06; d = 3 μm → Stk ≈ 0.14. The design target is to satisfy Stk ≥ 0.3 to ensure effective impact.

[0041] 3) Condensation growth time scale: Assuming the growth rate G≈2×10-5m / s, the growth characteristic time τ of a radius of 1μm is ≈0.050s (for illustration only, actual calibration requires an energy and mass transfer model).

[0042] 4) Dew point and steam volume: The steam volume fraction is adjusted from 0.8% to 3.0%, and optimized in conjunction with cooling capacity, target particle size increase and secondary dehumidification capacity.

[0043] In Table 1, silicon sealing rings can be selected as the material and seal. They are installed at the connection points of each part, such as between the gas injection and mixing section 1 and the cooling section 2, between the cooling section 2 and the condensation growth chamber 3, and between the condensation growth chamber 3 and the inertial impact separator 4.

[0044] The temperature in the cooling section 2 and the condensation growth chamber 3 of this invention determines the amount of usable water vapor. This temperature can be adjusted according to the concentration of particulate matter. For example, when the pure water vapor generated by the steam generator is 60°C and the temperature in the cooling section 2 and the condensation growth chamber 3 is 5°C, the usable water vapor pressure difference is 19.93 - 0.87 = 19.06 kPa; when the pure water vapor generated by the steam generator is 80°C and the temperature in the cooling section 2 and the condensation growth chamber 3 is 5°C, the usable water vapor pressure difference is 47.37 - 0.87 = 46.5 kPa. At this time, the amount of particulate matter that can be processed is twice that at 60°C. However, if the amount of water vapor is too high, it will greatly increase the humidity at the outlet, thereby increasing the difficulty of dehumidification. Therefore, the steam generator is controlled to generate pure water vapor at 60~80°C, and the temperature of the cooling medium in the heat exchange structure is 4~5°C.

[0045] This invention employs a pre-mixing and post-cooling method, uniformly injecting and mixing water vapor before it enters the cooling section 2 to form a supersaturated central area. This avoids the problem of condensation on the wall surface that is common in traditional high-flow-rate cooling devices, preventing secondary release of droplets. A stable inertial separation field is formed by a narrow nozzle 42 with right-angle or acute-angle bends. The narrow nozzle 42, with a width of 0.3~1.0mm and a length of 20~80mm, combined with right-angle or acute-angle bends, ensures that the condensed and grown droplets have a Stokes number ≥0.3 at a characteristic velocity of 10~20m / s, guaranteeing efficient droplet collection by deviating from the mainstream. A secondary dehumidification module and a reheat module are added to ensure that the outlet dew point is ≤-15℃, or even ≤-20℃, while achieving particle removal, thus balancing particle removal with the low humidity requirements of cleanrooms. This invention can be connected to cleanroom ductwork or fan filter unit (FFU) units for easy expansion. The monitoring and control module ensures the stability and reliability of the operation process. By reducing energy consumption and the frequency of consumable replacement, the operating cost of this invention can be reduced by approximately 25–40% compared to traditional multi-stage filtration systems; at the same time, it does not generate additional waste, which contributes to green production.

[0046] This invention rapidly grows particles <300nm into 1–5μm droplets through condensation and growth, achieving an inertial impaction collection efficiency of over 95%. Compared to simple HEPA filtration, the residual concentration of submicron particles can be reduced by an order of magnitude under the same pressure drop. The overall pressure drop of this invention is controlled below 600Pa, lower than multi-stage HEPA / ULPA series solutions (typically >1000Pa). Fan energy consumption can be reduced by approximately 20–30%, and the impactor plates can be repeatedly washed and reused, avoiding frequent filter replacements. This invention employs a two-stage dehumidification module and a reheat module, making it more suitable for semiconductor process environments than traditional wet collection methods, avoiding process defects caused by excessively humid air. This invention uses only pure water as the raw material medium throughout the entire process, without adding chemical collectors, ensuring that no additional organic / inorganic contaminants are introduced, meeting the air chemical cleanliness requirements for chip processing.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A submicron particle removal device, characterized in that, The system includes a gas injection and mixing section (1), a cooling section (2), a condensation growth chamber (3), and an inertial impact separator (4) connected in sequence. The gas injection and mixing section (1) is provided with an air inlet (10) and a water vapor inlet (11). The air entering from the air inlet (10) contains submicron particles, and the water vapor inlet (11) introduces water vapor, which mixes with the air. The cooling section (2) is provided with a heat exchange structure, and the condensation growth chamber (3) is provided with a rectifier plate and a guide plate. The inertial impact separator (4) is provided with a guide channel (41), a slit nozzle (42), and an impact collection plate (43). The slit nozzle (42) is connected to the condensation growth chamber (3), and an exhaust channel (40) is formed between the slit nozzle (42) and the impact collection plate (43). The air after the submicron particles are removed is discharged through the exhaust channel (40), and the condensate is discharged through the guide channel (41).

2. The submicron particle removal device according to claim 1, characterized in that, The device also includes a steam generator, which is connected to the water inlet (11) of the gas injection and mixing section (1) via a venturi tube or a multi-point tangential injector (21). The steam generator produces pure water steam at 60~80°C.

3. The submicron particle removal device according to claim 1, characterized in that, The heat exchange structure is a jacketed heat exchanger (20) or a coil heat exchanger, and the temperature of the cooling medium inside the heat exchange structure is 4~5℃.

4. The submicron particle removal device according to claim 1, characterized in that, Submicron particles grow into droplets of 1~5 μm in the condensation growth chamber (3).

5. The submicron particle removal device according to claim 1, characterized in that, The exhaust channel (40) is a bend exhaust channel (40), the guide groove (41) is located on the side of the impact collection plate (43) close to the ground, the guide groove (41) has a slope towards the ground, and a one-way drain valve (44) and a liquid collection chamber are installed at the end in sequence.

6. The submicron particle removal device according to claim 5, characterized in that, The angle of the curved exhaust channel (40) is less than or equal to 90°.

7. The submicron particle removal device according to claim 5, characterized in that, The impact collection plate (43) is a drawer-type structure with a hydrophilic coating on its surface.

8. The submicron particle removal device according to claim 1, characterized in that, The device also includes a secondary dehumidification module and a reheat module. The secondary dehumidification module is connected to the exhaust channel (40), and the reheat module is connected to the secondary dehumidification module. The secondary dehumidification module includes a low-temperature condensation unit or a membrane dehumidification unit.

9. The submicron particle removal device according to claim 8, characterized in that, The dew point of the air discharged from the secondary dehumidification module and the reheat module is less than or equal to 15°C.

10. The submicron particle removal device according to claim 1, characterized in that, The device also includes a monitoring and control module, which includes a programmable controller and temperature sensors, humidity sensors, dew point sensors, differential pressure sensors, flow sensors and particle counting sensors connected to the programmable controller. The temperature sensor and humidity sensor are installed in the gas injection and mixing section (1), the cooling section (2) and the exhaust channel (40); the dew point sensor is installed in the exhaust channel (40); the differential pressure sensor, the flow sensor and the particle counting sensor are installed in the water and gas inlet (11) and the exhaust channel (40).

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