TWM655950U - High efficiency purification treatment device for exhaust gas containing hydrofluoric acid - Google Patents

Abstract

A high-efficiency purification treatment device for waste gas containing hydrofluoric acid includes a shell, a rotor, a power device, a liquid infusion pipe and an exhaust pipe; the shell defines a working chamber and has an air inlet and a water outlet; the rotor is rotatably arranged in the working chamber, and has two radially parallel extending cover plates and a filling area defined between the two cover plates, and the filling area is connected to the working chamber at the periphery of the rotor; the power device is used to drive the rotor to rotate; the liquid infusion pipe is connected to the filling area and has a water outlet nozzle located at an axis of the rotor, and the liquid infusion pipe is used to introduce aqueous solution into the filling area; the exhaust pipe is connected to the filling area and has an exhaust port; wherein the air inlet is used to introduce waste gas containing hydrofluoric acid into the working chamber, and the waste gas containing hydrofluoric acid is discharged from the exhaust port in sequence through the filling area and the exhaust pipe.

Description

High-efficiency purification treatment device for waste gas containing hydrofluoric acid

This novel invention relates to a high-efficiency purification treatment device for waste gas containing hydrofluoric acid, and in particular to a device that uses high-speed liquid droplets to remove hydrofluoric acid from waste gas.

Hydrofluoric acid (HF) is an inorganic acid commonly used in semiconductor manufacturing processes, especially in etching processes. In the past, waste gas containing hydrofluoric acid was mostly treated by wet scrubbing in a scrubber, but studies have found that the scrubber is not efficient in removing hydrofluoric acid gas, and the lower the concentration of hydrofluoric acid in the waste gas, the worse the removal efficiency.

In order to improve the above-mentioned problem of poor removal efficiency, the existing technology proposes to add a cationic surfactant to the scrubbing liquid to increase the capture efficiency of fluoride ions. Even so, the technology of using the wet scrubbing method to treat waste gas containing hydrofluoric acid still has several obvious problems: (1) The scrubbing tower occupies a large volume; (2) The particle size and concentration of the water mist are difficult to control; (3) If the waste gas contains particulate matter, the two-fluid nozzle in the scrubbing tower is easily blocked, so it is not suitable for treating waste gas containing both hydrofluoric acid and particulate matter; (4) The surfactant must be consumed during operation, which will increase the treatment cost.

In view of this, the main purpose of this new technology is to provide a waste gas treatment technology that can effectively remove hydrofluoric acid even without adding a surfactant.

In order to achieve the above and other purposes, the present invention provides a high-efficiency purification treatment device for waste gas containing hydrofluoric acid, which includes a shell, a rotor, a power device, a liquid delivery pipe and an exhaust pipe; the shell defines a working chamber and has an air inlet and a water outlet, the air inlet and the water outlet are respectively connected to the working chamber; the rotor is rotatably arranged in the working chamber, and has two radially parallel extending cover plates and a filler defined between the two cover plates. The filling area is connected to the working chamber at the periphery of the rotor; the power device is used to drive the rotor to rotate; the liquid infusion pipe is connected to the filling area and has a water outlet nozzle located at one axis of the rotor, and the liquid infusion pipe is used to introduce the aqueous solution into the filling area; the exhaust pipe is connected to the filling area and has an exhaust port; wherein the air inlet is used to introduce the hydrofluoric acid waste gas into the working chamber, and the hydrofluoric acid waste gas is discharged from the exhaust port in sequence through the filling area and the exhaust pipe.

This new type of treatment device uses a rotor to convert aqueous solution into high-speed, tiny droplets or liquid films due to the centrifugal force. It not only increases the surface area of the aqueous solution and the chance of contact with hydrofluoric acid, but also allows a large number of high-speed droplets to collide violently with exhaust gas. Therefore, even without the addition of cationic surfactants, this new type of treatment device can still effectively remove hydrofluoric acid.

10: Shell

11: Working chamber

12: Air intake

13: Drainage outlet

14: Upper cover

20: Rotor

21: Cover plate

22: Filling area

23: Ring screen plate

30: Power device

40: Infusion tube

41: Water nozzle

50: Exhaust pipe

51: Exhaust port

60: Water atomizing nozzle

70: Gas pipe

Figure 1 is a cross-sectional schematic diagram of the first embodiment of the novel high-efficiency purification treatment device for hydrofluoric acid-containing waste gas.

Figure 2 is a cross-sectional schematic diagram of the second embodiment of the new high-efficiency purification treatment device for hydrofluoric acid-containing waste gas.

Figure 3 is a cross-sectional schematic diagram of the third embodiment of the new high-efficiency purification treatment device for hydrofluoric acid-containing waste gas.

Figure 4 is a cross-sectional schematic diagram of the fourth embodiment of the novel high-efficiency purification treatment device for hydrofluoric acid-containing waste gas.

Figure 5 is a cross-sectional schematic diagram of the fifth embodiment of the novel high-efficiency purification treatment device for hydrofluoric acid-containing waste gas.

Please refer to Figure 1, which shows the first embodiment of the new high-efficiency purification device for hydrofluoric acid-containing waste gas, which includes a housing 10, a rotor 20, a power device 30, a liquid delivery pipe 40 and an exhaust pipe 50.

The housing 10 defines a working chamber 11 and has an air inlet 12, a water outlet 13 and an upper cover 14. The air inlet 12 and the water outlet 13 are respectively connected to the working chamber 11. The water outlet 13 is usually located at the bottom of the housing 10. The air inlet 12 is used to introduce the waste gas containing hydrofluoric acid. The novel treatment device can be used to treat low-concentration waste gas containing hydrofluoric acid. In the working occasion where the concentration of hydrofluoric acid in the waste gas is less than 50ppm, or even less than 10ppm, the novel treatment device can effectively remove hydrofluoric acid, and its hydrofluoric acid removal efficiency can reach more than 85%. In a possible implementation, the waste gas containing hydrofluoric acid may also contain particulate matter (such as PM10 particles). Under the condition that the inlet concentration of particulate matter in the waste gas containing hydrofluoric acid is less than 30mg/m^3, the removal rate of particulate matter by the new treatment device can still reach more than 80%. That is, the new treatment device can be used to treat waste gas containing low-concentration hydrofluoric acid and particulate matter at the same time.

The rotor 20 is rotatably disposed in the working chamber 11, and has two radially parallel extending cover plates 21, a filling area 22 defined between the two cover plates 21, and a plurality of coaxial but unequally calibrated annular screen plates 23. The filling area 22 is connected to the working chamber 11 at the periphery of the rotor 20, and the annular screen plates 23 are disposed in the filling area 22 and have a plurality of screen holes. In a possible implementation, the filling area may also be filled with granular fillers to increase the liquid film area.

The power device 30 is used to drive the rotor 20 to rotate, and it usually includes a motor and a shaft, and may also include a speed reducer and/or other transmission mechanism not shown in the figure. Among them, other shaft seals may also be provided between the rotor 20 and the housing 10 and the power device 30 to increase airtightness and fix the rotor 20.

The liquid infusion pipe 40 is connected to the filling area 22 and has a water outlet nozzle 41 located at the axis of the rotor 20. The liquid infusion pipe 40 is used to introduce the aqueous solution, and the water outlet nozzle 41 can spray the aqueous solution toward the annular screen plate 23. When the rotor 20 is driven to rotate, centrifugal force is generated to throw the aqueous solution out. During the process, an acceleration of up to 100G may be generated to disperse the aqueous solution into the form of droplets or liquid films, thereby increasing the contact area between the phases, and then forcing the materials in different phases to contact each other. Since the aqueous solution will be corrosive after absorbing hydrofluoric acid, a pH adjuster, such as sodium hydroxide, can also be added to the aqueous solution to convert hydrofluoric acid into sodium fluoride to reduce its corrosiveness. In a possible implementation, the aqueous solution can be circulated, and the pH adjuster can adjust the pH value of the circulated aqueous solution to greater than 7, or even further adjust the pH value to greater than 8. It should be noted that since the present invention does not rely on the water outlet nozzle 41 to form tiny droplets, the water outlet hole of the water outlet nozzle 41 can use a larger pore diameter, so even if the hydrofluoric acid waste gas further contains particulate matter, the water outlet nozzle will not be blocked during the circulation of the aqueous solution.

The exhaust pipe 50 is connected to the filling area 22 and has an exhaust port 51. The exhaust pipe 50 and a section of the liquid infusion pipe 40 located in the working chamber 11 can be coaxially arranged, and the diameter of the exhaust pipe 50 is larger than that of the liquid infusion pipe 40, that is, the liquid infusion pipe 40 is partially sheathed in the exhaust pipe 50.

In a real-plant test, the exhaust gas flow was set to 4.4 NCMM, the rotor speed was 1150rpm, the circulating water volume of the aqueous solution was 85 LPM, the water tank overflow was 0.4 LPM, and no surfactant was added during the test. Under the condition of controlling the pH value of the aqueous solution to be greater than 8, the removal efficiency of hydrofluoric acid can reach more than 85%, and the removal efficiency of particulate matter can also reach more than 80%.

Please refer to FIG. 2, which shows a second embodiment of the novel high-efficiency purification treatment device for waste gas containing hydrofluoric acid. The second embodiment is similar to the first embodiment, and the main difference is that it further includes at least one water atomizing nozzle 60 disposed in the working chamber 11. Since the air inlet 12 and the air outlet 51 are closed during the shutdown of the rotor 20, there is still a possibility that the waste gas containing hydrofluoric acid leaks into the working chamber 11 through the air inlet 12 and the air outlet 51. Therefore, when the rotor 20 is not rotating and the air inlet 12 and the air outlet 51 are closed (i.e., when the rotor is shut down), the water atomizing nozzle 60 can be used to inject the pH-added waste gas into the working chamber 11. The aqueous solution of the adjuster is introduced into and rinses the working chamber 11. For example, when the pH adjuster is sodium hydroxide, even if the exhaust gas containing hydrofluoric acid leaks into the working chamber 11 when the rotor 20 is shut down, the sodium hydroxide in the aqueous solution can convert the hydrofluoric acid into sodium fluoride, thereby reducing the concern that the parts in the working chamber 11 (such as the inner wall of the casing, the rotor and its shaft) will be corroded by hydrofluoric acid.

Please refer to Figure 3, which shows the third embodiment of the novel high-efficiency purification treatment device for hydrofluoric acid-containing waste gas. It is similar to the first embodiment, and the main difference is that it further includes at least one air supply pipe 70 disposed in the working chamber 11 of the shell 10. When the rotor 20 is stopped, that is, the rotor 20 is not rotating and the air inlet 12 and the air outlet 51 are closed, the air supply pipe 70 can be used to introduce air, nitrogen or inert gas into the working chamber 11 to make the air pressure in the working chamber 11 higher than the air pressure on the upstream side of the air inlet 12 and the downstream side of the air outlet 51, thereby preventing the hydrofluoric acid-containing waste gas from leaking into the working chamber 11 through a higher chamber pressure, and playing a role in preventing the parts in the working chamber from being corroded by hydrofluoric acid.

Please refer to Figure 4, which shows the fourth embodiment of the novel high-efficiency purification treatment device for hydrofluoric acid-containing waste gas. It is similar to the first embodiment, and the main difference is that a water atomizing nozzle 60 and an air supply pipe 70 are provided in the working chamber 11 at the same time. The working principles of the water atomizing nozzle 60 and the air supply pipe 70 are similar to those described in the second and third embodiments, and both can protect or prevent the parts in the working chamber from being corroded by hydrofluoric acid.

Please refer to Figure 5, which shows the fifth embodiment of the novel high-efficiency purification treatment device for waste gas containing hydrofluoric acid. It is similar to the third embodiment, and the main difference is that the air supply pipe 70 is arranged at the air inlet 12 and the air outlet 51 (located between the air inlet and exhaust valves and the working chamber), and can also be used to introduce air, nitrogen or inert gas to make the air pressure in the working chamber 11 higher than the air pressure on the upstream side of the air inlet 12 and the downstream side of the air outlet 51, which plays a role in preventing the parts in the working chamber from being corroded by hydrofluoric acid.

10: Shell

11: Working chamber

12: Air intake

13: Drainage outlet

14: Upper cover

20: Rotor

21: Cover plate

22: Filling area

23: Ring screen plate

30: Power device

40: Infusion tube

41: Water nozzle

50: Exhaust pipe

51: Exhaust port

Claims (6)

A high-efficiency purification treatment device for waste gas containing hydrofluoric acid comprises: a housing defining a working chamber and having an air inlet and a water outlet, the air inlet and the water outlet being connected to the working chamber respectively; a rotor rotatably arranged in the working chamber, the rotor having two radially parallel extending cover plates and a filling area defined between the two cover plates, the filling area being connected to the working chamber at the periphery of the rotor; a power device for to drive the rotor to rotate; a liquid delivery pipe connected to the filling area and having a water outlet nozzle located at an axis of the rotor, the liquid delivery pipe is used to introduce the aqueous solution into the filling area; and an exhaust pipe connected to the filling area and having an exhaust port; wherein the air inlet is used to introduce the hydrofluoric acid-containing waste gas into the working chamber, and the hydrofluoric acid-containing waste gas is discharged from the exhaust port through the filling area and the exhaust pipe in sequence. As described in claim 1, the high-efficiency purification treatment device for waste gas containing hydrofluoric acid, wherein the aqueous solution is added with a pH adjuster, and the pH adjuster is used to adjust the pH value of the aqueous solution to greater than 7. A high-efficiency purification treatment device for waste gas containing hydrofluoric acid as described in claim 2, wherein the pH adjuster is sodium hydroxide. As described in claim 1, the high-efficiency purification treatment device for waste gas containing hydrofluoric acid, wherein the rotor further has a plurality of coaxial annular screen plates of different diameters, and the screen plates are arranged in the filling area. The high-efficiency purification treatment device for waste gas containing hydrofluoric acid as described in claim 2 further includes at least one water atomizing nozzle disposed in the working chamber, wherein when the rotor is not rotating and the air inlet and the air outlet are both closed, the water atomizing nozzle is used to introduce the aqueous solution added with the pH adjuster into and rinse the working chamber. The high-efficiency purification treatment device for waste gas containing hydrofluoric acid as described in claim 1 or 5 further includes at least one air supply pipe arranged in the housing, wherein, when the rotor is not rotating and the air inlet and the air outlet are closed, the air supply pipe is used to introduce air, nitrogen or inert gas to make the air pressure in the working chamber higher than the air pressure on the upstream side of the air inlet and the downstream side of the air outlet.

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