JPH09866A - Process and device for treatment of exhaust gas - Google Patents

Abstract

PURPOSE: To provide a process in which the use of a wet electric dust collector is not required in the constitution of the treatment process and a device thereof for exhaust gas containing dust and sulfur dioxide. CONSTITUTION: Exhaust gas is introduced into a cooling dust removing column 31, brought into contact with atomized droplet particles, and then extracted therefrom, and fed into a second chamber of a closed tank divided into a first chamber 5, the second chamber 6 and a third chamber 7 by a first interstructure 2 and a second interstructure 3, and blown into absorption fluid in the first chamber through an exhaust gas dispersion tube 9. The exhaust gas in the upper section is raised inside an exhaust gas rising cylinder 10, and the rising exhaust gas is made to collide with an exhaust gas collision plate 26, from the end of which exhaust gas cleaning fluid is flowed down in the liquid curtain shape, and brought into contact with the exhaust gas fluid curtain to be exhausted out of an exhaust gas outlet 11, and introduced into a mist eliminator 12 to remove the droplets in the exhaust gas, and then exhausted into atmosphere. The exhaust gas cleaning fluid on the second interstructure is introduced into an exhaust gas cleaning fluid tank 31 and stored therein, and then fed to a dispersion mechanism of the exhaust gas collision plate, and a part of the cleaning fluid to be fed is introduced into a solid-liquid separation device 33, and the cleaning fluid thus provided is stored in a clean exhaust gas cleaning fluid tank 32, and transferred to the exhaust gas cleaning fluid tank 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for treating exhaust gas containing dust and sulfurous acid gas.

[0002]

2. Description of the Related Art Conventionally, an exhaust gas containing dust and sulfurous acid gas is introduced into a cooling dust removal tower, where the exhaust gas is cooled and dust removed,
It is introduced into a desulfurization device for desulfurization treatment, then the desulfurized exhaust gas is introduced into a mist eliminator, where droplet particles (mist) in the exhaust gas are removed, and then introduced into a wet electrostatic precipitator, where A method of treating exhaust gas released to the atmosphere through an exhaust gas exhaust pipe after removing dust remaining in the exhaust gas is widely used.

By the way, in such an exhaust gas treatment method, in order to remove dust contained in the exhaust gas,
As described above, the wet electrostatic precipitator is used, but this is a large-scale device, its cost is very high, and its installation area is wide. It has become one of the major factors that cause it. Therefore, it is desirable to omit the installation of such a wet electrostatic precipitator if possible, but the dust concentration regulation in the exhaust gas discharged to the atmosphere is becoming stricter year by year. From the point of view, the wet electrostatic precipitator must be arranged.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for treating exhaust gas containing dust and sulfurous acid gas, which method does not require the use of a wet electrostatic precipitator. .

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, in the method for treating an exhaust gas containing dust and sulfurous acid gas, (i) the exhaust gas is introduced into a cooling dust removing tower, brought into contact with atomized droplet particles, and then discharged from the cooling dust removing tower. (Ii) The exhaust gas extracted from the cooling dust removal tower is supplied to the first partition plate and the second partition plate located above the first partition plate.
Supplying to the second chamber in the sealed tank, the interior of which is partitioned by the partition plate into a first chamber, a second chamber adjacent above the first chamber, and a third chamber adjacent above the second chamber. , (Iii)
Blowing the exhaust gas supplied to the second chamber into the absorbent contained in the first chamber through a lung gas dispersion pipe vertically provided in a through hole formed in the first partition plate, (iv) first Connecting the exhaust gas existing in the upper space of the chamber between the first chamber and the third chamber, and raising the upper end of the exhaust gas rising cylinder located above the surface of the second partition plate; (v) rising exhaust gas The exhaust gas rising through the cylinder to the third chamber has a liquid flow-down wall and a liquid dispersion mechanism arranged above the exhaust gas flow-up cylinder, and the exhaust gas cleaning liquid flows down like a liquid curtain from the tip of the liquid flow-down wall. The exhaust gas impinging plate that is in contact with the liquid curtain, and (vi) exhausting the exhaust gas after contacting the liquid curtain in the third chamber from the exhaust gas outlet arranged in the third chamber. (Vii) Mist emission of the exhaust gas after being discharged from the third chamber After being introduced into the exhaust gas and removing the droplet particles contained in the exhaust gas, it is extracted from the mist eliminator, and (viii) The exhaust gas extracted from the mist eliminator is released into the atmosphere without wet electrostatic precipitating treatment. , (Ix) Extracting the exhaust gas cleaning liquid staying on the second partition plate in the closed tank out of the closed tank, introducing it into the exhaust gas cleaning liquid tank, and storing it (x) exhaust gas cleaning liquid stored in the exhaust gas cleaning liquid tank Supplying to the liquid dispersion mechanism arranged on the collision plate, (xi) introducing part of the exhaust gas cleaning liquid supplied to the exhaust gas collision plate into the solid-liquid separation device, (xii) clarification obtained by the solid-liquid separation device Provided is a method for treating exhaust gas, which comprises storing the exhaust gas cleaning liquid in a clear exhaust gas cleaning liquid tank, and (xiii) transferring the stored liquid in the clear exhaust gas cleaning liquid tank to the exhaust gas cleaning liquid tank.

Further, according to the present invention, an exhaust gas cooling dust removing tower for cooling and removing the exhaust gas, a desulfurization device for desulfurizing the exhaust gas from the cooling dust removing tower, and droplet particles in the exhaust gas discharged from the desulfurization device A mist eliminator for removing, and an exhaust gas discharge tube for discharging exhaust gas from the mist eliminator into the atmosphere, wherein the desulfurization device includes a first partition plate and a second partition plate located above the first partition plate. A closed chamber whose interior is divided into a first chamber, a second chamber adjacent above the first chamber, and a third chamber adjacent above the second chamber,
An exhaust gas inlet formed in the peripheral wall of the second chamber, an exhaust gas outlet arranged in the third chamber, a through hole formed in the first partition plate, and an exhaust gas dispersion pipe vertically provided in the through hole, The exhaust gas rising cylinder, which communicates the first chamber and the third chamber and whose upper end is located above the surface of the second partition plate, is disposed above the exhaust gas rising cylinder, and the exhaust gas is provided on the liquid falling wall and the liquid falling wall. An exhaust gas collision plate having a liquid dispersion mechanism for supplying the cleaning liquid, an exhaust gas cleaning liquid discharge pipe for transferring the exhaust gas cleaning liquid staying on the second partition plate to the exhaust gas cleaning liquid tank, and a stored liquid of the exhaust gas cleaning liquid tank are arranged on the exhaust gas collision plate. The exhaust gas cleaning liquid supply pipe to be supplied to the liquid dispersion mechanism and the exhaust gas cleaning liquid withdrawal pipe for withdrawing a part of the exhaust gas cleaning liquid flowing through the exhaust gas cleaning liquid supply pipe and transferring it to the solid-liquid separation device and the exhaust gas cleaning liquid withdrawal pipe. Drawn out A solid-liquid separator for solid-liquid separation of the cleaning liquid, a clarified exhaust gas cleaning liquid tank for storing the clarified exhaust gas cleaning liquid obtained by the solid-liquid separator, and a pipe for transferring the liquid stored in the clarified exhaust gas cleaning liquid tank to the exhaust gas cleaning liquid tank An exhaust gas treatment device is provided.

Next, the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic diagram of an exhaust gas treating apparatus of the present invention. In this figure, 1 is an exhaust gas desulfurization apparatus, 1'is a closed tank, 2
Is a first partition plate, 3 is a second partition plate, 4 is a top plate, 5 is a first chamber, 6
Is a second chamber, 7 is a third chamber, 8 is an exhaust gas introduction duct, 9 is an exhaust gas dispersion pipe, 10 is an exhaust gas rising pipe, 11 is an exhaust gas discharge duct, 12 is a mist eliminator, 13 is an exhaust gas exhaust pipe, and 14 is an exhaust gas cleaning liquid. Extraction pipe, 15 is an exhaust gas collision plate, 16 is a liquid dispersion plate, 17, 34, 36, 38, 39 are exhaust gas cleaning liquid supply pipes, 21 is a cooling dust removing tower, 21 'is a closed cylindrical body, 22 is an exhaust gas introduction duct, 23 Is an exhaust gas cooling liquid discharge pipe, 25 is an exhaust gas cooling liquid supply pipe, 26 is an exhaust gas cooling liquid spray nozzle, 28 is an exhaust gas duct, 29 is a mist eliminator, 31 is an exhaust gas cleaning liquid tank, 32 is a clear exhaust gas cleaning liquid tank, and 33 is a solid liquid. Separators, 37, 40 are exhaust gas cleaning liquid draw-out pipes, 41 are clear exhaust gas cleaning liquid transfer pipes, 4
2, 43 and 46 are clarified exhaust gas cleaning liquid supply pipes, 50 and 5
1, 52 are liquid level controllers, 53 is a flow meter, L ₁ is an absorbing liquid,
L ₂ is an exhaust gas cleaning liquid, and L ₃ is an exhaust gas cooling liquid.

The exhaust gas desulfurization apparatus 1 shown in FIG. 1 is composed of a large closed tank 1 ', and the inside of the tank is composed of a first partition plate 2 and a second partition plate 3 located above the first partition plate 5'. And a second chamber 6 adjacent above the first chamber and a third chamber 7 adjacent above the second chamber. The upper space of the third chamber is sealed by the top plate 4. The first partition plate 2 may be horizontal or slightly inclined. The second partition plate 3 may be horizontal or inclined, and its inclination angle is not particularly limited. The absorbing liquid L ₁ is contained inside the first chamber 5. In addition, the first chamber has a stirrer and an absorbing liquid L ₁
An oxygen-containing gas jet nozzle or the like (not shown) used when it is necessary to supply oxygen therein is provided.
An exhaust gas inlet is arranged on the peripheral wall of the second chamber 6, and an exhaust gas introducing duct 8 is connected to this inlet. A special device is not particularly required to be provided in the space of the second chamber, but a spray nozzle (not shown) for spraying the absorbing liquid can be provided if necessary. An exhaust gas outlet is arranged on the top plate 4 arranged above the third chamber 7, and an exhaust gas discharge duct 11 is connected to this outlet. Further, an exhaust gas discharge tube 13 is connected to the exhaust gas discharge duct 11 via a mist eliminator 12. The exhaust gas outlet can be arranged on the peripheral wall. Outside the closed tank 1 ′, the exhaust gas cleaning liquid L ₂ staying on the second partition plate 3 forming the floor surface of the third chamber 7 is discharged into the exhaust gas collision plate 15 in the third chamber.
A circulation line is provided to circulate the liquid in the liquid dispersion mechanism. This circulation line is for the cleaning liquid extraction pipe 1
4, cleaning liquid tank 31, circulation pump 35, and cleaning liquid supply pipe 3
It consists of 4, 35, 38 and 17.

The first partition plate 2 is provided with a large number of through holes that connect the first chamber 5 and the second chamber 6, and the tip of each through hole is the absorbing liquid L _{1 of} the first chamber. An exhaust gas dispersion pipe 9 extending inside is vertically provided. Further, the first partition plate 2 and the second partition plate 3 are provided with openings for arranging the exhaust gas rising cylinder 10, and the exhaust gas existing in the upper space of the first chamber 5 is provided in these openings. An exhaust gas rising cylinder 10 for introducing into the third chamber 7 is connected. In this case, the upper end of the exhaust gas rising cylinder 10 protrudes above the surface of the second partition plate, and the cleaning liquid on the second partition plate becomes second.
A certain amount is retained on the partition plate. The cross-sectional shape of the exhaust gas rising cylinder can be various shapes such as a circle, a square, and a rectangle. Above the exhaust gas rising cylinder 10,
An exhaust gas collision plate 15 is arranged.

The exhaust gas collision plate 15 used in the present invention has a liquid flow-down wall and a liquid dispersion mechanism for supplying a cleaning liquid to the liquid flow-down wall. This collision plate is used for the exhaust gas rising cylinder 10
Has the effect of receiving the rising exhaust gas on its lower surface and forming droplet particles contained in the exhaust gas as a liquid film on its lower surface. Further, this collision plate has a liquid flow-down wall and a liquid dispersion mechanism for supplying the cleaning liquid to the liquid flow-down wall, and has an action of causing the cleaning liquid to flow down like a liquid curtain from the tip of the liquid flow-down wall.

The overall shape of the exhaust gas impingement plate 15 is not particularly limited, but is generally a hollow structure having a central portion formed on the exhaust gas impingement surface and a liquid flow-down wall on the periphery thereof, the lower end opening. The exhaust gas collision surface can be various surfaces such as a flat surface, a curved surface, and an uneven surface. The liquid flow-down wall surface may be any surface as long as the liquid flows down along the surface and can flow down from the tip thereof, and may be a flat surface, a curved surface, an uneven surface, or the like. Examples of the shape of the collision plate having the liquid flow-down wall include a box shape, a hollow hemispherical shape, and a shape in which the central portion projects upward from the peripheral edge portion, for example, a hat shape.

In the present invention, for the exhaust gas collision plate,
A liquid dispersion mechanism is provided. FIG. 2 shows an example of a collision plate provided with a liquid dispersion mechanism. In FIG. 2, reference numeral 15 denotes a collision plate, which is composed of an exhaust gas collision portion A and a liquid flow-down wall B formed on the periphery thereof. The liquid dispersion mechanism arranged on the collision plate supplies the cleaning liquid to the liquid flow-down wall of the collision plate. The liquid supply pipe 17 opens below the central portion of the collision plate and the opening of the liquid supply pipe. And a liquid dispersion plate 16 disposed at the tip opening of the short cylinder 20 that surrounds the short cylinder 20.
Consists of The liquid dispersion plate 16 may have a structure that ejects or flows out the liquid radially. 3 and 4 are perspective views of the liquid dispersion plate.

When the exhaust gas cleaning liquid is supplied through the liquid supply pipe 17 to the exhaust gas collision plate 15 having the liquid dispersion mechanism shown in FIG. 2, the cleaning liquid is jetted or discharged in the direction of arrow a, and the liquid of the collision plate 15 is discharged. It is received on the inner surface of the falling wall B, flows down on the inner surface, and flows down from the tip of the liquid falling wall in the direction of arrow b in a liquid curtain shape. The exhaust gas that has risen in the exhaust gas riser collides with the lower surface of the collision portion A of the collision plate 15, and its flow path is guided by the liquid flow-down wall B to change downward, and is directed downward from the tip of the liquid flow-down wall. The cleaning liquid thus formed passes through the liquid curtain, and comes into contact with the liquid curtain during the passage. Then, the dust in the exhaust gas is removed from the exhaust gas by contact with the liquid curtain.

A cooling dust removing tower 21 is arranged upstream of the exhaust gas desulfurization apparatus 1. This cooling dust removal tower 21
Is a closed cylindrical body 21 ', an exhaust gas introduction duct 22 connected to the top plate thereof, an exhaust gas outlet formed on the peripheral wall of the closed cylindrical body, and an exhaust gas cooling liquid L ₃ stored in the bottom of the closed cylindrical body.
A coolant circulation line for supplying the upper part of the sealed tubular body, and the cooling liquid L ₃ from the spray nozzles 26 for spraying. Further, the cooling liquid circulation line is provided with the cooling liquid drain pipe 23.
And a circulation pump 24 and a cooling liquid supply pipe 25.

To treat the exhaust gas using the system shown in FIG. 1, the exhaust gas is introduced into the cooling dust removal tower 21 through the exhaust gas introduction duct 22. In the cooling dust removing tower 21, the cooling liquid L ₃ is sprayed from the spray nozzle 26 through the cooling liquid extracting pipe 23, the circulation pump 24 and the cooling liquid supply pipe 25, and the exhaust gas introduced into the cooling dust removing tower 21 is sprayed by this spray. The exhaust gas is contacted with the generated cooling liquid particles, dust is removed from the exhaust gas, and the exhaust gas is cooled and humidified. Coolant supply pipe 2
A part of the cooling liquid flowing through 5 is withdrawn through the cooling liquid withdrawal pipe 27, and accordingly, the replenishing cooling liquid is supplied through the cooling liquid replenishment pipe 27 '. As the cooling liquid, water, an absorbing liquid, an alkaline aqueous solution or the like is used. Cooling dust removal 21
The dust concentration in the exhaust gas supplied to the
The concentration of mg / Nm ³ and SO ₂ is 300 to 800 ppm.

The exhaust gas treated in the cooling dust removal tower 21 is passed through the exhaust gas duct 28, the mist eliminator 29, and the exhaust gas introduction duct 8 connected to the cooling dust removal tower 21 to the second chamber 6 of the closed tank of the exhaust gas desulfurization apparatus. Is introduced into the first chamber 5 and blown into the absorbent L ₁ in the first chamber 5 through the exhaust gas dispersion pipe 9. The exhaust gas blown into the absorbing liquid L ₁ rises as bubbles, and a floss layer composed of a mixed phase of bubbles and absorbing liquid is formed above the gas ejection holes of the dispersion pipe.
While the exhaust gas rises as bubbles in the absorption liquid, contaminants such as dust and sulfur dioxide contained in the exhaust gas are captured by the absorption liquid and removed from the exhaust gas. The dust concentration in the exhaust gas introduced into the desulfurization device 1 is usually 150 mg / Nm.
^{It is 3} or less, preferably 100 mg / Nm ³ or less. The exhaust gas purified in this way is diffused from the floss layer to the upper space, and then introduced into the third chamber 7 through the exhaust gas rising cylinder 10. A collision plate having a liquid flow-down wall and a liquid dispersion mechanism is arranged in the third chamber, and the liquid dispersion mechanism has an exhaust gas cleaning liquid L ₂ staying on the upper surface of the second partition plate 3 forming the floor surface thereof. The cleaning liquid is circulated through the cleaning liquid extraction pipe 14, the cleaning liquid tank 31, the pump 35, and the cleaning liquid supply pipes 34, 38, and 17 for discharging the cleaning liquid, and the cleaning liquid is discharged from the tip of the liquid flow-down wall of the collision plate 15. It is flowing like a curtain. The exhaust gas that has collided with the lower surface of the collision plate 15 passes through the falling liquid curtain of the cleaning liquid, but at that time, the exhaust gas comes into contact with the falling liquid curtain of the cleaning liquid, and the dust remaining in the exhaust gas is captured by the liquid curtain. It is removed from the exhaust gas.

The exhaust gas in the third chamber is an exhaust gas discharge duct 11 connected to the opening of the top plate 4 arranged above the third chamber.
Through the mist eliminator 12 to remove the absorbing liquid particles and the like contained in the gas, and then enter a heater (not shown) if necessary, Here, after the mist remaining in the gas is vaporized, it is discharged to the atmosphere through the exhaust gas discharge cylinder 13.

The cleaning liquid that has flowed down in the form of a liquid curtain from the tip of the liquid flow-down wall of the collision plate 15 drops and stays on the upper surface of the second partition plate 3 and is returned from here to the cleaning liquid tank 31 through the cleaning liquid discharge pipe 14.

As the exhaust gas dispersion pipe 9, various types can be used, such as one having a gas ejection hole on the peripheral wall surface at the lower end, one having a nozzle structure at the lower end, and the like. FIG.
The perspective view of the gas dispersion pipe which has a gas ejection hole in the peripheral wall surface of a lower end part is shown in FIG. In FIG. 5, 9 indicates a gas dispersion pipe, and 5
Reference numeral 5 denotes a gas ejection hole formed on the peripheral wall surface of the lower end portion.

The exhaust gas cleaning liquid tank 31 acts as a storage tank for temporarily storing the cleaning liquid L ₂ transferred from the upper surface of the second partition plate 3 forming the floor surface of the third chamber, and also receives the replenishing cleaning liquid tank. Shows the action as. The cleaning solution for replenishment is
The cleaning liquid tank 31 is supplied from the clarified exhaust gas cleaning liquid tank 32 through a pipe 42, a pump 43, and pipes 44, 45.

A part of the cleaning liquid circulated in the liquid dispersion mechanism attached to the collision plate 15 or the spray nozzle 18 is withdrawn from the circulation line, for example, the cleaning liquid withdrawing pipe 14 or the cleaning liquid supply pipe 36, and is taken out of the system. Can be discharged,
It is preferably introduced into the absorbent L ₁ through conduit 37, as shown in FIG. By such an operation, the component composition of the cleaning liquid circulated in the liquid dispersion mechanism of the collision plate can always be kept within a predetermined range, and the ability of removing the solid content in the exhaust gas of the cleaning liquid can be kept high.

The amount of the total cleaning liquid flown down from the liquid flow-down wall of the collision plate 15 in the form of a liquid curtain is usually 0.2 to about 1 m ³ / hr of the total exhaust gas converted to the standard state rising from the exhaust gas rising cylinder 10. 0.8 kg / hr, preferably 0.2-0.
It is 3 kg / hr. Such an amount of cleaning liquid is applied to the collision plate 15
By flowing the liquid in the form of a liquid curtain from the liquid flow-down wall, it is possible to effectively remove the dust contained in the exhaust gas rising in the exhaust gas rising cylinder 10. In the exhaust gas rising in the exhaust gas rising column 10, in addition to the dust originally contained in the exhaust gas to be treated supplied to the cooling dust removal tower 21, the absorbing liquid L
Solid fine particles such as gypsum contained in ₁ are included,
In the case of the present invention, such solid fine particles can be effectively removed.

Referring again to FIG. 1, part of the cleaning liquid supplied from the exhaust gas cleaning liquid tank 31 through the pump 35 and the cleaning liquid supply pipe 38 to the liquid dispersion mechanism arranged on the exhaust gas collision plate 15 is supplied to the cleaning liquid drawing pipe 40. It is introduced into the solid-liquid separation device 33 through. The solid-liquid separation device 33 may have any structure as long as it can separate and remove solid particles from the liquid, and may be, for example, a thickener, a centrifuge, a filter or the like.

The clear cleaning liquid obtained by the solid-liquid separation device 33 is introduced into the clear cleaning liquid tank 32 through the pipe 41 and stored therein. The liquid stored in the clarification cleaning liquid tank 32 is supplied to the pipe 4
2, it is transferred to the cleaning liquid tank 31 through the pump 43, the pipe 44, and the pipe 45.

The cleaning liquid for replenishment is supplied by the cleaning liquid supply pipe 4 for replenishment.
It is supplied to the clarification washing liquid tank 32 through 7.

The stored liquid in the clarification cleaning liquid tank 32 is a clear liquid which does not substantially contain solid particles, and therefore, if necessary,
As the cooling liquid which is used in the cooling dust removing tower 21 and is not preferable in the presence of solid particles, it can be supplied to the cooling dust removing tower 21 from the pipe 46 through the cooling liquid supply pipe 27 '.
Further, the cleaning liquid stored in the cleaning liquid tank 31 contains dust, but since the amount thereof is extremely small,
This cleaning liquid can also be used as a cleaning liquid for the mist eliminator 12 or 29 through the pipe 39, if necessary.

The liquid level controller 50 shown in FIG. 1 is for adjusting the liquid level of the stored liquid in the cleaning liquid tank 31 to a constant height, and works in conjunction with the flow rate control valve 50 '. Liquid level controller 5
Reference numeral 1 is for adjusting the liquid level of the stored absorbent in the first chamber 5 to a constant height, and works in conjunction with the flow rate adjusting valve 51 '.
The liquid level controller 52 is for adjusting the liquid level of the stored liquid in the clarification cleaning liquid tank 32 to a constant height, and the flow rate control valve 5
Works with 2 '. The flow meter 53 is for adjusting the amount of cleaning liquid flowing through the pipe 40, and is a flow rate adjusting valve 53 ′.
Works with

As the absorbing liquid L ₁ used in the first chamber 5, various liquids which are reactive with sulfurous acid gas are used. As such a material, for example, a solution or slurry containing an alkaline substance such as an alkali metal compound or an alkaline earth metal compound is used, and particularly, a calcium hydroxide slurry or a calcium carbonate slurry is used. When calcium carbonate slurry or calcium hydroxide slurry is used as the absorbing liquid, these calcium compounds react with sulfurous acid gas to form calcium sulfite. In this case, by introducing air or oxygen into the absorbing liquid. , Calcium sulfate can be obtained.

As the exhaust gas cleaning liquid, any liquid can be used as long as it is a liquid. As such a cleaning liquid, any readily available liquid such as water or seawater can be used. In particular, the use of water is preferable because it does not become dust even if the droplet particles remain in the treated exhaust gas.

[0030]

Next, the present invention will be described in more detail with reference to examples. Example 1 Using the exhaust gas treating apparatus having the structure shown in FIG. 1, dust: 1
50 mg / Nm ³ , SO ₂ : 800 volppm, O ₂ :
After treating the flue gas containing 5 vol% in the cooling dust removal tower 21,
It processed with the desulfurization apparatus 1. The conditions of the desulfurizer in this case are as follows. (1) Diameter of the closed tank 1: 3.2 m (2) Height of the first chamber 5: 4 m (3) Height of the second chamber 6: 2 m (4) Height of the third chamber 7: 2.5 m (5) Diameter of exhaust gas dispersion pipe 9: 4 inches and number: 11
0 (6) Diameter of exhaust gas rising pipe 10: 410 mm and number:
Six (7) Structure of the exhaust gas collision plate: the structure shown in FIG. 2 (8) Height of the stationary liquid surface of the absorbing liquid in the first chamber 5: 3 m The structure of the exhaust gas dispersion pipe 9 shown in FIG. The position of the gas ejection hole 55 provided on the peripheral wall surface of the lower end portion was set to a position 180 mm below the absorbing liquid surface. Further, in the first chamber 5 of the closed tank 1 ′ having the structure shown in FIG. 1, a water slurry liquid having a gypsum concentration of 20% by weight was previously stored as an absorbing liquid so that the height thereof was 3 m.

Next, exhaust gas (SO ₂ : 800 ppm, dust: 150 mg /
Nm ³ ) from the exhaust gas introduction duct 8 to 40,000 Nm ³
/ H was supplied into the second chamber 6 of the desulfurization apparatus 1 for desulfurization treatment. In this case, air is jetted at 200 Nm ³ / h from the oxygen-containing gas jet nozzle arranged at a position 2500 mm below the stationary liquid level of the absorbent in the first chamber 5, and the stirrer is rotated to stir the absorbent. I went.

As shown in FIG. 1, a cleaning liquid tank 31, a clarification cleaning liquid tank 32, and a solid-liquid separator (thickener) 33 are arranged outside the closed tank 1 ', and a cleaning liquid is supplied through a cleaning liquid supply pipe 47. To supply those cleaning liquid tanks 3
The cleaning liquid was previously stored in the 1 and the clear cleaning liquid tank 32. As shown in FIG. 1, the cleaning liquid in the cleaning liquid tank 31 is supplied through a cleaning liquid supply pipes 38 and 17 to a liquid disperser tank arranged on the collision plate 15, and the liquid is discharged from the tip of the liquid flow-down wall of the collision plate. The cleaning liquid accumulated on the second partition plate 3 forming the floor of the third chamber 7 while being made to flow in the form of a curtain is withdrawn through the cleaning liquid discharge pipe 14 to the outside of the closed tank, and the cleaning liquid tank 31
Sent back to. In this case, the third liquid is supplied via the cleaning liquid supply pipe 17.
The total amount of cleaning liquid supplied to the liquid dispersion mechanism arranged on the collision plate 15 in the room was 0.2 kg / h with respect to the amount of exhaust gas 1 Nm ³ / h supplied from the exhaust gas introduction duct 8.
In addition, a part of the cleaning liquid flowing through the cleaning liquid supply pipe 38 is withdrawn and introduced into the thickener 33, and the clear cleaning liquid after the dust obtained in the thickener 33 is separated is passed through the pipe 41 to the clarifying cleaning liquid tank 32. Then, the clarification cleaning liquid in the clarification cleaning liquid tank 32 was further introduced into the cleaning liquid tank 31 via the pipe 42, the pump 43, the pipe 44 and the pipe 45.

As a result of the treatment of the exhaust gas as described above, the solid particles in the cleaning liquid flowing through the cleaning liquid supply pipe 38 (this is the dust contained in the exhaust gas in advance and the particles from the first chamber 5). The amount of gypsum particles contained in the exhaust gas is 800 mg / L or less, the dust concentration in the exhaust gas after passing through the mist eliminator 12 is 2.0 mg / Nm ³ , and the SO ₂ concentration is It was 25 ppm.

Next, for comparison, when the exhaust gas was treated without the provision of the exhaust gas collision plate, the dust concentration in the exhaust gas after passing through the mist eliminator 12 was 4.0.
It was as high as mg / Nm ³ .

[0035]

EFFECTS OF THE INVENTION According to the present invention, a high dust removal rate, which is difficult to achieve by the conventional method, can be easily obtained with low power consumption without requiring an extra increase in treatment cost, and its industrial significance is great. Is.

[Brief description of drawings]

FIG. 1 shows a schematic view of an example of an exhaust gas treatment system of the present invention.

FIG. 2 is an explanatory diagram of an example of an exhaust gas collision plate provided with a liquid dispersion mechanism.

FIG. 3 shows a perspective view of an example of a liquid dispersion plate.

FIG. 4 is a perspective view of another example of the liquid dispersion plate.

FIG. 5 shows a perspective view of an example of an exhaust gas dispersion pipe.

[Explanation of Codes] 1 desulfurization device 1'closed tank 2 first partition plate 3 second partition plate 4 top plate 5 first chamber 6 second chamber 7 third chamber 8 exhaust gas introduction duct 9 exhaust gas dispersion pipe 10 exhaust gas rising cylinder 11 Exhaust gas discharge duct 12, 29 Mist eliminator 13 'Exhaust gas discharge tube 14 Cleaning liquid extraction pipe 15 Exhaust gas collision plate 16 Liquid dispersion plate 17 Cleaning liquid supply pipe 21 Exhaust gas cooling and dust removing tower 31 Exhaust gas cleaning liquid tank 32 Clearing exhaust gas cleaning liquid tank 33 Solid-liquid separation device 47 Exhaust gas cleaning liquid supply pipe 55 Gas injection hole L ₁ Absorbing liquid L ₂ Exhaust gas cleaning liquid L ₃ Exhaust gas cooling liquid

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B01D 50/00 501 B01D 50/00 501G 502A 502 53/18 E 53/18 53/34 ZAB 53 / 34 ZAB

Claims (4)

[Claims] 1. A method for treating an exhaust gas containing dust and sulfurous acid gas, comprising: (i) introducing the exhaust gas into a cooling dust removal tower, bringing it into contact with atomized droplet particles, and then withdrawing from the cooling dust removal tower; (Ii) The inside of the exhaust gas extracted from the cooling dust removal tower has a first partition plate and a second partition plate located above the first partition plate.
Supplying to the second chamber in the closed tank divided into a second chamber above the first chamber and a second chamber above the first chamber and a third chamber above the second chamber, and (iii) supplying to the second chamber. The discharged exhaust gas is blown into the absorbing liquid contained in the first chamber through an exhaust gas dispersion pipe vertically provided in a through hole formed in the first partition plate, (iv) existing in the upper space of the first chamber The exhaust gas to be communicated between the first chamber and the third chamber, and to raise the inside of the exhaust gas rising cylinder whose upper end is located above the surface of the second partition plate, (v) through the exhaust gas rising cylinder to the third chamber The rising exhaust gas has a liquid flow-down wall and a liquid dispersion mechanism arranged above the exhaust gas rising cylinder, and the exhaust gas cleaning liquid flows down from the tip of the liquid flow-down wall to the exhaust gas collision plate. Causing the exhaust gas to come into contact with the liquid curtain while causing the collision, (vi) after coming into contact with the liquid curtain Discharging the exhaust gas from an exhaust gas outlet provided in the third chamber, (vii) introducing the exhaust gas discharged from the third chamber into a mist eliminator, removing droplet particles contained in the exhaust gas, and then removing the mist eliminator. (Viii) releasing the exhaust gas extracted from the mist eliminator into the atmosphere without performing wet electrostatic precipitating treatment, (ix) sealing the exhaust gas cleaning liquid remaining on the second partition plate in the sealed tank (X) Supplying the exhaust gas cleaning liquid stored in the exhaust gas cleaning liquid tank to the liquid dispersion mechanism arranged on the exhaust gas collision plate, (xi) Exhaust gas collision plate A part of the exhaust gas cleaning liquid to be supplied to the solid-liquid separator, (xii) storing the clear exhaust gas cleaning liquid obtained by the solid-liquid separator in a clear exhaust gas cleaning liquid tank, (xiii) the clear exhaust gas Transferring the liquid contained in the cleaning liquid tank into the exhaust gas washing liquid tank, processing method of an exhaust gas characterized by. 2. The method according to claim 1, wherein an exhaust gas cleaning liquid spray nozzle is provided above the third chamber in the closed tank, and the exhaust gas cleaning liquid stored in the exhaust gas cleaning liquid tank is supplied to the spray nozzle for spraying. 3. An exhaust gas cooling dust removal tower for cooling and removing dust from an exhaust gas, a desulfurization device for desulfurizing exhaust gas from the cooling dust removal tower, and a mist eliminator for removing droplet particles in the exhaust gas discharged from the desulfurization device. And an exhaust gas discharge tube that discharges the exhaust gas from the mist eliminator into the atmosphere, wherein the desulfurization device has a first partition plate and a second partition plate located above the first partition plate. Chamber and first
A closed chamber partitioned into a second chamber adjacent above the chamber and a third chamber adjacent above the second chamber, an exhaust gas inlet formed on the peripheral wall of the second chamber, and a third chamber The exhaust gas outlet, the through hole formed in the first partition plate, the exhaust gas dispersion pipe vertically provided in the through hole, the first chamber and the third chamber, and the upper end thereof is the surface of the second partition plate. On the second partition plate, there is an exhaust gas riser located at a higher position, an exhaust gas collision plate disposed above the exhaust gas riser cylinder and having a liquid flow-down wall and a liquid dispersion mechanism for supplying an exhaust gas cleaning liquid to the liquid flow-down wall. The exhaust gas cleaning liquid withdrawal pipe for transferring the accumulated exhaust gas cleaning liquid to the exhaust gas cleaning liquid tank, the exhaust gas cleaning liquid supply pipe for supplying the stored liquid of the exhaust gas cleaning liquid tank to the liquid dispersion mechanism arranged on the exhaust gas collision plate, and the exhaust gas cleaning liquid supply pipe Part of the circulating exhaust gas cleaning liquid is extracted and transferred to the solid-liquid separation device. Exhaust gas cleaning liquid withdrawing pipe, a solid-liquid separation device for solid-liquid separating the exhaust gas cleaning liquid drawn through the exhaust gas cleaning liquid withdrawing pipe, and a clear exhaust gas cleaning liquid tank for storing the clear exhaust gas cleaning liquid obtained by the solid-liquid separation device An exhaust gas treatment apparatus comprising a pipe for transferring a liquid stored in a clarified exhaust gas cleaning liquid tank to the exhaust gas cleaning liquid tank. 4. The apparatus according to claim 3, wherein an exhaust gas cleaning liquid spray nozzle is disposed above the third chamber of the closed tank, and the spray nozzle and the exhaust gas cleaning liquid tank are connected via a pipe.