JPS6359337A - Method and apparatus for treating exhaust gas - Google Patents

Abstract

PURPOSE:To reduce trouble due to dust, by spraying an alkali washing solution such as KOH or NaOH exhaust gas containing a specific silicon compound and an acid component as a high speed jet stream to promote the hydrolysis and neutralizing reaction of the exhaust gas in a spray atmosphere. CONSTITUTION:Untreated exhaust gas is guided to the washing chamber 4 of a jet scrubber main body A through an untreated exhaust gas introducing port 3 while a high pressure alkali washing solution C is injected from a high pressure jet nozzle 2 and air is involved in high speed jet spray 1 within the washing chamber 4 to generate negative pressure. As a result, the exhaust gas is sucked in the jet spray 1 to perform highly efficient gas-liquid contact and, therefore, the hydrolytic reaction of the silicon compound such as SiH2Cl2 or SiF4 in the exhaust gas and the neutralizing reaction of an acid component such as HCl or Cl2 in the gas are promoted. The dust in the exhaust gas or the dust formed by reaction contacts with the water droplets of the high speed jet spray 1 to be collected, and the water droplets are further grown during the falling through a skirt part 6 to be introduced into a liquid receiving tank B to be collected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to 5i11tel, 5iC1, SiF4.
Silicon compounds containing halogens such as SiH4 and l1C1,H
The first invention relates to an exhaust gas treatment method and an improvement of the apparatus for treating exhaust gas containing acids such as P and CI2 with high efficiency and without trouble.
iH1CIt, SiC+4. A cleaning liquid (C) containing alkaline components such as potassium hydroxide and sodium hydroxide is sprayed with a high-speed jet onto exhaust gas containing silicon compounds containing halogens such as SiF, SiH, and acids such as HCI, IIF, and Cl2. A second invention relates to a method for treating exhaust gas characterized by promoting a hydrolysis reaction and a neutralization reaction of the alkaline cleaning liquid (C) of the exhaust gas in the spray (1), and a second aspect of the invention relates to a method for discharging the alkaline cleaning liquid (C) at high pressure. a high-pressure jet nozzle (2) that forms a high-speed jet spray (1) of fine water droplets;
Silicon compounds containing halogens such as SiH4, IIcI, I
An exhaust gas inlet (3) for untreated exhaust gas containing acid content such as P, C1, etc. is provided in the cleaning chamber (4), and an exhaust gas inlet (3) having a smaller cross-sectional area than the cleaning chamber (4) is provided following the outlet of the cleaning chamber (4). Throat part (
5), and a skirt part (6) whose cross-sectional area gradually increases following the throat part (5), and the cleaning chamber (4), throat part (5), and skirt part (6) form a jet scrubber body. (^) consists of the jet scrubber body (^)
Liquid receiver 1'ff (
The present invention relates to an exhaust gas treatment device characterized by comprising B).

(Prior Art) Currently, a filling type scrubber, a perforated plate type scrubber (b) (shown in FIG. 3), etc. have been used in exhaust gas treatment equipment. Here, a perforated plate type scrubber (D) will be explained as a conventional example. For the perforated plate type scrubber (D), the scrubber body (21
), perforated plates (11) are installed in multiple stages, and each stage is provided with an overflow cylinder (12) for the cleaning liquid (C) overflowing in the upper stage to flow down to the lower stage. A water supply nozzle (13) for discharging cleaning liquid (C) is arranged on the uppermost perforated plate (11), and the cleaning liquid (C) discharged from here overflows through the overflow cylinder (12). , gradually flows down to the lower perforated plate (11).On the other hand, the exhaust gas introduced into the interior from the exhaust gas inlet (3) provided at the bottom of the scrubber body (21) flows through the perforated plate (11). The cleaning liquid (C) rises through the through hole (15), during which time it floats up as bubbles in the cleaning liquid (C) that has accumulated on the perforated plate (11), and is gradually purified through gas-liquid contact. The purified exhaust gas passes through a mist removal device (7) provided at the top of the scrubber body (21), and after the mist in the exhaust gas is removed, it is released into the atmosphere. However, 5iHxCI
When processing exhaust gas containing silicon compounds such as t, 5iC1, SiF, SiH4, a large amount of powder is produced! ! 1 (1G) is generated, or when a large amount of dust (10) is generated from the source and a large amount of dust (10) is contained in the exhaust gas, or when the cleaning liquid (C) and the exhaust gas are A viscous substance is produced by a chemical reaction through gas-liquid contact, and the through holes (1) of the perforated plate (11) are formed.
5) or the overflow pipe (12), continuous operation is not possible, so the perforated plate type scrubber (D
) must be installed in multiple units and used in a batch manner to clean the perforated plate (11) of the idle ones, which increases the number of columns and increases the equipment cost. The drawback is that they tend to get bigger, and if the clogging is severe, cleaning must be done more frequently.
Another drawback was that maintenance was extremely time-consuming and costly.

In addition, in this method, a fan (20) is installed to push in untreated exhaust gas or to suck in purified exhaust gas, but not only untreated exhaust gas but also trace amounts of powder remaining in the purified exhaust gas are
There have also been accidents where the fan (10) adheres to the blade guard of the fan (20) and grows during long-term use, causing the blade to become unbalanced and causing damage to the fan (20).

These points also apply to a filling type scrubber in which the scrubber body is filled with a filler.

(Object of the present invention) The present invention has been made in view of the conventional example, and its object is to 5iHxCI2, 5iCI4. SiF
4. Silicon compounds containing halogens such as Si■, and HCI
, H.F., C.I.

It is possible to continuously process exhaust gases that contain acids such as, and which would generate a large amount of dust and viscous substances and clog the processing equipment when treated with an alkaline cleaning solution. To provide an exhaust gas treatment method and its device which have no moving parts, are less likely to break down, and are easy to maintain.

(Means for solving problems) Hereinafter, the present invention will be described in detail according to illustrated embodiments.

The jet scrubber main body (^) is composed of an uppermost cleaning chamber (4), a throat section (5) following it, and a skirt section (6) following the throat section (5). Washing room (4
) is cylindrical and has a high-pressure spray nozzle (2) vertically installed on its ceiling that sprays the cleaning liquid (C) under high pressure to form a high-speed jet spray (1) of fine water droplets, and the cleaning chamber (4)
An untreated exhaust gas inlet (3) is provided on the side of the tank. The spray pressure of the high pressure jet nozzle (2) is 1 to 5 g/
am', and the suction force is about -30+*mAq to -500s+sAq at the entrance of the exhaust gas introduction hole formed by the high-speed jet spray injected from the high-pressure jet nozzle (2). Also, the liquid-gas ratio = L/G is 3 to 100,
/is.

An exhaust gas introduction pipe (14) is connected to the untreated exhaust gas introduction port (3), and a cleaning nozzle (16) is installed in the exhaust gas introduction pipe (14). Exhaust gas introduction pipe (1
4) is installed on a downward slope toward the untreated exhaust gas inlet (3). A throat portion (5) having a smaller cross-sectional area than the cleaning chamber (4) is provided at the outlet of the cleaning chamber (4). The lower part of the cleaning chamber (4) is the throat part (5).
) is shaped like a morning glory so that it flows smoothly into the A skirt portion (6) whose cross-sectional area gradually increases is provided following the throat portion (5). A liquid receiving tank (B) connected to the skirt part (6) is installed below the jet scrubber body (^), and contains cleaning liquid (C).

Liquid receiving tank (B) on the opposite side of the jet scrubber body (^)
A mist removal device (7) is installed above the. A baffle plate layer (17) bent at an angle effective for the flow of exhaust gas is installed inside the mist removal device (A).
An air outlet (18) is provided on the ceiling. In addition, a cleaning liquid (C) supply pipe (19) and a circulation pump (8) are installed in the liquid receiving tank (B), and the circulation pump (8) is used for cleaning the high-pressure jet nozzle (2) and the mist removal device (7). Bag N
(9). Further, the liquid receiving tank (B) is also provided with a filter W (not shown) for appropriately overflowing the cleaning liquid (C) accumulated inside and filtering the overflowing cleaning liquid (C).

The exhaust gas discharged from the manufacturing equipment and treated by the present invention is
5iHzClz, 5iC14, SiF4. S: Silicon compounds containing halogens such as H4, semiconductor exhaust gas containing acids such as C1, IF, C1, exhaust gas from glass melting processes, etc. In addition, there are other types such as blast furnace exhaust gas, cupola exhaust gas, incinerator exhaust gas, etc. , kiln exhaust gas, etc. Powder II
Items containing a large amount of (10) are also targeted.

The cleaning liquid (C) for exhaust gas treatment is an aqueous solution containing alkaline components such as potassium hydroxide and sodium hydroxide.

This alkaline cleaning solution (C) has an alkaline concentration of 0.1% to 1.
5% and pH 9 to 14 is used. The alkali concentration is appropriately selected depending on the type of untreated exhaust gas.

(Function) The untreated exhaust gas sent out from the manufacturing process is led to the cleaning chamber (4) of the jet scrubber body (8) through the untreated exhaust gas inlet (3). Washing room (4)
The cleaning liquid (C) is spouted out at high pressure from the high-pressure jet nozzle (2), becomes a high-speed jet spray (1) of fine water droplets, and is blown into the throat part (5), where it is narrowed and the flow rate is increased. The flow velocity is gradually decreased at the skirt portion (6), and the liquid receiver f1! (B). During this time, the air in the cleaning chamber (4) is drawn into the high-speed jet spray N (1) and has a negative pressure, and the aforementioned exhaust gas is sucked in and drawn into the high-speed jet spray (1), resulting in high efficiency. Gas-liquid contact is made, and detoxification is carried out according to the following reaction formula.

(Chemical reaction formula) ...Hydrolysis reaction formula... ■ n5iH,cl x+HzO-” (SiOIl,
)n+2nHcI where (SiOHz>n is polysiloxic acid.

■ 3SiF4+)120→2HtSiFg+5iOz
Here, H,5iFs is hexafluorosilicic acid.

■ SiF4"2H20-+SiO*"4HF The acid content generated by these chemical reactions is removed from the alkaline cleaning solution (4).
is neutralized.

In addition, fine powder n (10) in the exhaust gas generated by the chemical reaction mentioned above and dust carried from the production site (10)
comes into contact with the water droplets of the high-speed jet spray (1) and is collected at a very high rate. Powder JI!
The water droplets collected in (10) gradually grow into larger water droplets as they fall down the skirt part (6), and as mentioned above, the water droplets collect in the liquid receiving tank (6).
In the case of a semiconductor exhaust gas containing something like silane, which is poured into B), it is diluted with an inert gas to the lower explosive limit and introduced into the cleaning chamber (4). In this case, the semiconductor exhaust gas is hydrolyzed when it comes into contact with the cleaning liquid (C), producing a large amount of powder.
! (10) is generated and is collected and removed by the method described above.

Moreover, by using an alkaline liquid as the cleaning liquid (C), the exhaust gas containing acids such as HCl, HF, Ch, etc. is neutralized by gas-liquid contact as described above, and is recovered in the liquid receiving tank (B).

...Neutralization reaction formula... HF4NaO11→NaF+HtO HCI+NaOH-"NaCl+H,0 The exhaust gas purified in this way passes through the upper part of the liquid receiving tank (B) and enters the mist removal device (7).9Then, the mist is removed. While rising in the device (7), it passes through the baffle plate layer (17) and is released into the atmosphere after separating the mist in the exhaust gas. On the other hand, the circulation pump (8) installed in the liquid receiving tank (B) ) pumps up the cleaning liquid (C) from the liquid receiving tank (B), supplies it to the high pressure jet nozzle (2), and circulates the cleaning liquid (C).A part of the cleaning liquid (C) from the liquid receiving tank (B) is overflowed. The liquid is taken out of the receiver Ml (B), filtered, neutralized, diluted, and discharged into the river when the water quality falls below the standard value.A new cleaning liquid (C) in the same amount as the overflow cleaning liquid (C) is poured into the liquid. Receiver (
B), and the concentration of the cleaning liquid (C) in the liquid receiving tank (B) is kept constant. Also, although the mist removal device (7) continuously removes mist, a small amount of powder remains in the purified exhaust gas! ! ! (10) remains and this adheres to the surface of the baffle plate layer (1)).
) The cleaning liquid (C) is supplied from the circulation pump (8) to the cleaning device M (9) which automatically washes off the adhering powder (10). Also, during operation, as shown in Fig. 2, the inside of the exhaust gas inlet pipe (14) or the untreated exhaust gas inlet (3)
1 powder! ! (10) gradually accumulates, but by spraying the cleaning liquid (C) from the cleaning device nozzle, the powder tli (1
0) is washed away.

(Effect) The first invention, as in the above, 5iHtCIz, 5iCI4
．． A cleaning solution containing alkaline components such as potassium hydroxide and sodium hydroxide is sprayed at high speed onto exhaust gas containing silicon compounds containing halogens such as SiF4゜SiH, and acids such as HCI, I(F, CI2, etc.). The exhaust gas and the alkaline cleaning liquid come into contact with each other at a very high rate, promoting hydrolysis and neutralization reactions, and moreover, when they come into contact with the sprayed cleaning liquid, they undergo a detoxifying reaction. The dust generated by the reaction is immediately collected in fine water droplets, which has an excellent dust removal effect, and since the reaction is carried out in a spray state, there is no possibility that the reaction product will clog the processing equipment.

In addition, the second invention includes a high-pressure jet nozzle that jets alkaline cleaning liquid at high pressure to form a high-speed jet spray of fine water droplets, and S+1IzCIz, 5iCI+, SiF4.
Silicon compounds containing halogens such as ゜Sin<, llCl,
IIF, CI.

An exhaust gas inlet for untreated exhaust gas containing acids, such as The cleaning chamber, the throat part, and the skirt part constitute the jet scrubber main body, and a liquid receiving tank connected to the skirt part is provided below the jet scrubber main body, so that high-speed jet spray can be Negative pressure is created inside the scrubber body, and as a result, no fan is required to introduce untreated exhaust gas or release purified exhaust gas.
Not only does it not require the cost of powering the fan, it also eliminates fan damage caused by dust adhesion as in conventional systems.Furthermore, since there is no structural part inside the jet scrubber body where dust can become clogged, ,5iCI<,
Even if exhaust gas containing silicon compounds containing halogens such as SiF4 is detoxified to generate a large amount of dust, or exhaust gas containing large amounts of dust transported directly from the source is continuously treated for a long period of time, there is no effect. It does not cause trouble (especially clogging due to dust), can be operated continuously, requires significantly less equipment cost and installation area than conventional methods, and has the advantage of requiring almost no maintenance.

[Brief explanation of the drawing]

Figure 1: Flowchart of the present invention; Figure 2: Cross-sectional view of an embodiment of the cleaning chamber of the present invention; Figure 3:
Figure: Flow diagram of a conventional example. (^)...Jet scrubber body, (B)...Liquid receiving tank, (C)...Cleaning liquid, (
D)...Perforated plate scrubber, (1)...High speed jet spray, (2)...High pressure jet nozzle, (3)...Untreated exhaust gas inlet, (4)...Cleaning chamber, (5)...Throat part, (6)...Skirt part, (7)...Mist removal device, (8)...Circulation pump, (9)...Cleaning device, (10)... ...Dust, (11)...
・Perforated plate, (12)...Overflow tube, (13)...Water supply nozzle, (14)...Exhaust gas introduction pipe, (15)...Through hole, (16)...Washing nozzle, (1))...Baffle plate layer, (18)...
・Atmospheric outlet, (19)...Cleaning liquid supply pipe, (20)
...Fan, (21)...Scrubber body. Inventor: Ken Miyazaki Inventor: Akira Mazari

Claims (11)

[Claims] (1) SiH_2Cl_2, SiCl_4, SiF_4
, silicon compounds such as SiH_4, HCl, HF, Cl_2
A cleaning solution containing alkaline components such as potassium hydroxide and sodium hydroxide is sprayed with a high-speed jet onto the exhaust gas containing acids such as potassium hydroxide, sodium hydroxide, etc., and the hydrolysis reaction and neutralization reaction of the exhaust gas by the alkaline cleaning solution are promoted within the high-speed jet spray. Characteristic exhaust gas treatment method. (2) Adjust the spray pressure of high-speed jet spray to 1 to 5 kg/
2. The exhaust gas treatment method according to claim 1, wherein the exhaust gas treatment method is set to cm^2. (3) The concentration of the alkaline cleaning solution is 0.1% to 15%,
The exhaust gas treatment method according to claim 1, characterized in that the pH is adjusted to 9 to 14. (4) The exhaust gas treatment method according to claim 1, characterized in that L/G is 3 to 100 weight/weight. (5) A high-pressure jet nozzle that jets alkaline cleaning liquid at high pressure to form a high-speed jet spray of fine water droplets, and a SiH
_2Cl_2, SiCl_4, SiF_4, SiH_4
Silicon compounds containing halogens such as HCl, HF, Cl_
An exhaust gas inlet for untreated exhaust gas containing acids such as No. A jet scrubber main body is configured by a cleaning chamber, a throat part, and a skirt part by increasing the number of skirt parts.
An exhaust gas treatment device comprising a liquid receiving tank connected to a skirt portion below a jet scrubber body. (6) Adjust the spray pressure of high-speed jet spray to 1 to 5 kg/
cm^2, and the suction force at the exhaust gas introduction hole formed by high-speed jet spraying is -30 mmAq to -500 mmA.
The exhaust gas treatment device according to claim 5, characterized in that q. (7) The concentration of the alkaline cleaning solution is 0.1% to 15%,
The exhaust gas treatment device according to claim 5, characterized in that the pH thereof is set to 9 to 14. (8) The exhaust gas treatment device according to claim 5, characterized in that L/G is 3 to 100 weight/weight. (9) The stray gas treatment device according to claim 5, characterized in that the liquid receiving tank is provided with a mist removing device for removing mist of the clean gas discharged through the liquid receiving tank. (10) The exhaust gas device according to claim 5, characterized in that a circulation pump is installed in the liquid receiving tank, and the circulation pump is connected to a high-pressure jet nozzle. (11) The exhaust gas treatment device according to claim 9, characterized in that a cleaning device is installed in the mist removal device.