JPH0634893B2 - How to dispose of dust - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for treating dust in a gas with water, and in particular, a method capable of treating even if the particle diameter of dust is 0.1 μm or less. Regarding

[Conventional technology]

As a method for removing dust in gas with water, conventionally, a gas containing dust is bubbled in water to bring the dust into contact with water and capture it with water (underwater bubbling method).
Alternatively, a method (shower ring method) in which a gas containing dust is circulated in the form of shower water to bring the dust into contact with water droplets to capture the dust with water (shower ring method) is used.

[Problems to be solved by the invention]

However, in the above conventional method, the particle size is generally 0.1 μm.
Dust of m or more can be removed because there is sufficient chance of contact with water, but the particle size of dust is 0.1 μm or less, especially 0.05 μm.
In the following cases, there is an inconvenience that the removal rate is significantly reduced. That is, in the bubbling method, the fine dust is included in the bubbles generated when the gas is jetted into the water, and the opportunity to contact with the water cannot be obtained, so that the fine dust cannot be removed. Further, in the showering method, since the amount of fine dust is very small, there is not enough opportunity to associate with the mist droplets of the sprayed water and the dust cannot be removed.

For these reasons, it has been generally considered difficult to capture fine dust with water. For example, when the silane gas is burned and then the silicon dioxide (SiO ₂ ) generated by the burning of the silane gas in the combustion gas is treated with water and treated, the particle size of the silicon dioxide immediately after burning is almost 0.
It is less than 05 μm, and it is difficult to capture it with water by the conventional method, and most of it is released into the atmosphere without being captured, which is harmful to the human body.

Therefore, it has been desired to develop a method of completely capturing even the extremely small amount of dust as described above with water.

The present invention has been made in view of the above, and relates to a method of completely capturing dust with water even if the particle diameter of dust in the gas is 0.1 μm or less.

[Means for solving problems]

A feature of the present invention is that when capturing dust contained in a gas with water, water is added to a gas containing dust to pass through an orifice, and the outlet side of the orifice is set to atmospheric pressure or lower, and Dust is captured by water by passing the pressure difference between the upstream side and the downstream side under a differential pressure of 2500 mmAq or more.

〔Example〕

The figure shows an example in which the method of the present invention is applied to a silane gas combustion abatement apparatus, 1 is a silane gas combustion apparatus, 2 is a processing gas introduction pipe connected to the combustion apparatus 1, and 3 is water in the combustion apparatus 1. It is a water supply pipe to supply.

Next, 4 is an exhaust pipe connected to the bottom of the combustion apparatus 1. The exhaust pipe 4 is connected to a vacuum pump 7 via a valve 5 and a gas-liquid separator 6 which form an orifice described later. Reference numeral 8 is a filter press connected to the gas-liquid separator 6.

In the configuration as described above, for example, exhaust gas containing silane gas discharged from a semiconductor manufacturing apparatus (not shown) is introduced into the combustion apparatus 1 through the processing gas introduction pipe 2 and burned. As a result, most of the silane gas is converted to silicon dioxide. Next, water is added to the combustion gas accompanying the combustion through the water supply pipe 3. When water is added, it is effective to cool the combustion gas at the same time by passing the combustion gas into the shower formed water.

On the other hand, the vacuum pump 7 is operated, and the combustion gas containing fine particles of silicon dioxide and water are sucked from the bottom of the combustion device 1 in a gas-liquid two-phase state and passed through the valve 5. An orifice is formed in the valve 5 by appropriately adjusting the opening thereof, and the two-phase flow is vigorously stirred and ejected when passing through the orifice.
Then, at this time, the outlet side of the valve 5 is set to a pressure equal to or lower than atmospheric pressure,
When the differential pressure when passing through the valve 5 is set to 2500 mmAq or more, silicon dioxide having a particle size of 0.05 μm or less is mixed with water at the time of stirring and is captured by water.

The water thus containing silicon dioxide is introduced into the gas-liquid separator 6 and then treated in the filter press 8 and the silicon dioxide is taken out as a solid. On the other hand, the gas phase portion in the combustion gas is sucked into the vacuum pump 7 as it is and then released into the atmosphere.

As described above, according to this embodiment, even silicon dioxide having a particle size of 0.05 μm or less, which is generated immediately after the combustion of silane, can be captured by water and can be removed.

In the above configuration, the valve 5 is used as the orifice for passing the gas-liquid two-phase flow, but the same effect can be obtained by using a thin tube as the orifice.

Experimental Example Next, an experiment was carried out using the apparatus illustrated in the figure, which will be described.

Gas containing approximately equal amounts of silane, hydrogen and nitrogen 10 Nl / min
The fuel is burned in the combustion device 1 at a rate of 1, then water is added from the water supply pipe 3 and then passed through the valve 5, and at this time, the opening degree of the valve 5 is adjusted. As a result of observing the degree of white smoke in the gas exhausted from the vacuum pump 7 after changing and passing it, the results shown in the table were obtained.

As described above, the valve 5 outlet pressure is adjusted to -2 by closing and adjusting the valve 5.
Reduce the pressure below 500 mmAq and further reduce the differential pressure across valve 5 by 2
When it was 500 mmAq or more, fine powder having a particle size of 0.05 μm or less could be almost completely captured in water.

〔The invention's effect〕

(1) According to the method of the present invention, fine powder having a particle size of 0.05 μm or less can be captured in water. As a result, even silicon dioxide having a particle diameter of 0.05 μm or less immediately after the combustion of silane gas can be captured in water, and can be applied to a silane gas combustion apparatus, which is highly effective.

(2) As an orifice for passing a gas-liquid two-phase flow, a normal one such as a valve or a thin tube can be used, so that it can be easily constructed and is highly practical.

[Brief description of drawings]

The figure is a systematic diagram for explaining the processing method of the present invention. 1 ... Silane gas combustion device, 2 ... Process gas introduction pipe, 3
...... Water supply pipe, 4 ... Drainage pipe, 5 ... Valve, 6 ... Gas-liquid separator, 7 ... Vacuum pump, 8 ... Filter press

Claims (2)

[Claims] 1. When capturing dust contained in a gas with water, water is added to the dust-containing gas to allow the gas to pass through an orifice, and the outlet side of the orifice is set to atmospheric pressure or less, and upstream of the orifice. A method for treating dust, characterized in that the dust is captured with water by passing a pressure difference between the downstream side and the downstream side under a differential pressure of 2500 mmAq or more. 2. The method for treating dust according to claim 1, wherein the particle diameter of the dust is 0.1 μm or less.