JP3502467B2 - Exhaust gas treatment tank - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment tank,
More specifically, the present invention relates to an exhaust gas treatment tank in which an absorbent is contained in the tank, and harmful substances in the exhaust gas introduced into the tank are brought into contact with and removed by the absorbent, particularly an exhaust gas treatment tank most suitable as a jot bubbling reaction tank. Is.

[0002]

2. Description of the Related Art Wet flue gas desulfurization is widely used to remove sulfur dioxide, dust and other environmental pollutants from exhaust gas. The wet flue gas desulfurization method is a method in which an exhaust gas and a fixative slurry are subjected to a gas-liquid contact reaction to fix and remove sulfurous acid gas as a sulfate. The fixative slurry used is
A fixing agent that fixes sulfurous acid gas as a sulfate, for example, a slurry-like aqueous solution in which limestone is dissolved and / or suspended in water. Among them, a wet flue gas desulfurization device using a jet bubbling reaction tank as an exhaust gas treatment tank for removing the environmental pollutants in the exhaust gas by bringing the exhaust gas and the fixative slurry contained in the tank into gas-liquid contact, It is widely used as a device that has a high removal rate of environmental pollutants and is economically superior. Taking the case of removing the sulfurous acid gas in the exhaust gas as an example,
The structure of a conventional Jott bubbling reaction tank used in a wet flue gas desulfurization apparatus will be described below. A jet bubbling reaction tank is typically, for example, Japanese Patent Publication No. 55-3729.
As shown in FIG. 1 of Japanese Patent Publication No. 5 and FIG. 1 of Japanese Patent Publication No. 3-70532, a fixative slurry for fixing environmental pollutants such as sulfurous acid gas is contained in the lower part of the tank, and exhaust gas containing sulfurous acid gas is contained. Is a gas-liquid contact type reaction tank in which sulfur dioxide is fixed as a sulfate by reacting with a fixative while forming a jet bubbling layer by dispersing and introducing the fixative into a fixative slurry.

Further, referring to FIG. 5, a jet bubbling reaction tank (hereinafter simply referred to as a reaction tank) which uses limestone as a fixing agent and removes sulfurous acid gas in exhaust gas.
10 will be described. As shown in FIG. 5, the reaction tank 10 is divided into an exhaust gas outlet chamber 12, an exhaust gas inlet chamber 14 provided so as to cross the tank body, and a lower space for accommodating an absorbing liquid containing limestone in order from the top. Has been done. Exhaust gas outlet chamber 12
The exhaust gas inlet chamber 14 and the exhaust gas inlet chamber 14 are partitioned by a first partition plate 16 extending horizontally across the tank body, and the exhaust gas inlet chamber 14 and the lower space are separated by a second partition plate 18 extending parallel to the first partition plate 16.
It is partitioned by. The second partition plate 18 is the absorption liquid layer 2
It is located above the liquid level of 0 and forms a space portion 22 for flowing out the exhaust gas therebetween. The exhaust gas outlet chamber 12 is connected to the outlet duct 24, and the exhaust gas inlet chamber 14 therebelow is connected to the inlet duct 26. Further, the treated exhaust gas is supplied to the space 22.
As a gas riser to flow into the exhaust gas outlet chamber 12 from
A plurality of pipe-like communication pipes 28 (only one is shown in FIG. 5 for simplicity) penetrates through the exhaust gas inlet chamber 14 to form a space 22.
And the exhaust gas outlet chamber 12 are communicated with each other.

The exhaust gas dispersion pipe 30 communicates with the exhaust gas inlet chamber 14 at the upper end and descends downward from the second partition plate 18 of the exhaust gas inlet chamber 14 so as to be immersed in the slurry 20 at the lower end. A large number of small openings are provided at the lower end thereof, and the exhaust gas is dispersed in the absorbing liquid layer 20 through these openings to form a jet bubbling layer A. The jet bubbling layer A is a liquid-phase continuous gas-liquid contact layer composed of bubbles of exhaust gas and an absorbing liquid containing limestone. The lower part of the reaction tank 10 is adapted to accommodate the absorbing liquid layer 20, and the lower part of the tank is provided with a stirrer 32 for stirring the absorbing liquid, and for supplying oxygen necessary for immobilizing gypsum of sulfurous acid gas. An air supply pipe 34 having a jet nozzle for jetting an oxygen-containing gas such as air is provided. The stirrer 32 has a rotary shaft 36 extending downward from a drive device 38 on the tank via one of the communication pipes 28. In FIG. 5, 40 is a slurry supply pipe, and 42 is a gypsum slurry discharge pipe produced by the reaction.

The operation of the reaction tank 10 will be described below. In the lower part of the reaction tank 10 in FIG. 5, a slurry obtained by dissolving and / or suspending limestone powder that reacts with sulfurous acid gas and is immobilized on gypsum in water is stored as an absorption liquid. Exhaust gas is introduced from the inlet duct 26 through the exhaust gas inlet chamber 14 through the opening of the exhaust gas dispersion pipe 30 to below the liquid surface of the absorbing liquid, and jets out in a jet form to rise while bubbling. As a result, the so-called jet bubbling layer A is generated below the liquid surface. Sulfurous acid gas reacts with water, oxygen and limestone to form gypsum and is removed, and the resulting gypsum is slurried.

The exhaust gas from which the sulfurous acid gas has been removed is discharged to the outside of the system through the communication pipe 28 and the exhaust gas outlet chamber 12 by the outlet duct 24. On the other hand, the slurry containing the crystallized gypsum in a concentrated manner is discharged from the discharge pipe 42. Further, an amount of limestone slurry commensurate with the slurry extracted from the discharge pipe 42 is continuously supplied to the reaction tank 10 from the slurry supply pipe 40.

[0007]

By the way, in the conventional reaction tank, the gas riser for communicating the space above the jot bubbling layer with the exhaust gas outlet chamber and allowing the treated exhaust gas rising from the jot bubbling layer to flow out to the exhaust gas outlet chamber is provided. It is composed of a number of pipe-shaped communicating pipes that penetrate the exhaust gas inlet chamber. The pipe-shaped communication tube has an inner diameter of 300 mm to 600
It is formed of a pipe of mm and extends upward from the peripheral edge of the opening of the second partition plate to the peripheral edge of the opening of the first partition plate. In the second partition plate, a large number of communication tubes 28 and a large number of inner diameters of 50 mm to 20
The exhaust gas dispersion pipes 30 of 0 mm are arranged in an array as shown in FIG. 6, for example.

However, as the amount of exhaust gas treated increases, the reaction tank becomes larger and larger, and the transverse dimension of the tank becomes larger accordingly. Therefore, when the treated exhaust gas is caused to flow from the space above the absorbent to the exhaust gas outlet chamber in the reaction tank, there is a problem that the treated exhaust gas is difficult to smoothly flow out. In order to allow the treated exhaust gas to flow out smoothly, it is necessary to evenly arrange a number of communication pipes that extend through the exhaust gas inlet chamber, but this hinders the flow of the treated exhaust gas in the exhaust gas inlet chamber. , Even distribution does not flow into the exhaust gas dispersion pipe. Furthermore, since the communication pipe is joined to the opening peripheral edges of the first partition plate and the second partition plate on site, increasing the number of communication pipes further increases the amount of construction work on site. Since the cost per unit amount of work on site construction is much higher than that of factory production, if the amount of site construction increases, the construction cost of the reaction tank increases.

In view of the above situation, the object of the present invention is to
Provided is an exhaust gas treatment tank having a gas riser structure capable of smoothly flowing out the treated exhaust gas to the exhaust gas outlet chamber without adversely affecting the flow of the exhaust gas in the exhaust gas inlet chamber even in a large exhaust gas treatment tank. That is.

[0010]

In order to achieve the above object, the exhaust gas treating tank according to the present invention introduces the exhaust gas into the absorbing liquid contained in the tank and brings them into gas-liquid contact to remove harmful substances in the exhaust gas. In the exhaust gas treatment tank to be contacted and removed by the absorbing liquid, the exhaust gas outlet chamber, which is arranged in order from the top in the treatment tank, communicates with the outlet duct for discharging the exhaust gas,
An exhaust gas inlet chamber that is partitioned from the exhaust gas outlet chamber by a first partition plate that extends in the transverse direction of the treatment tank and communicates with an inlet duct that introduces the exhaust gas, and a second exhaust gas chamber that extends in the transverse direction of the treatment tank.
A gas riser having a space portion partitioned from the exhaust gas inlet chamber by a partition plate, further having a hollow portion having a band-shaped cross section that penetrates the exhaust gas inlet chamber and communicates the space portion and the exhaust gas outlet chamber,
An exhaust gas dispersion cylinder descending from the exhaust gas inlet chamber to the space portion, the first partition plate having a first strip-shaped opening extending along the exhaust gas introduction direction introduced from the inlet duct to the exhaust gas inlet chamber,
The second partition plate has a second strip-shaped opening arranged at a position facing the first strip-shaped opening and a plurality of opening holes arranged in a region other than the second strip-shaped opening, and the gas riser has a hollow side wall. Second
The exhaust gas dispersion cylinder is provided so as to extend upward from the peripheral edge of the strip-shaped opening and reach the peripheral edge of the first strip-shaped opening that opposes, and the exhaust gas dispersion cylinder is provided so as to descend downward from the hole edge of the opening hole and be immersed in the absorbing liquid. It is characterized by being.

The exhaust gas treating tank according to the present invention can be applied without limitation as long as it is a treating tank for contacting and removing environmental pollutants such as sulfurous acid gas from the exhaust gas with an absorbing liquid. Further, the shape of the tank body of the exhaust gas treatment tank is not particularly limited, and its cross section may be rectangular, circular, or polygonal. The shape of the hollow section of the gas riser, that is, the band-shaped opening is not necessarily limited to the rectangular shape, and the widthwise side edges do not need to be parallel.
The width does not have to be the same for all the band-shaped openings, and the band-shaped openings do not necessarily have to be evenly spaced. The position and the size of the strip-shaped opening are determined according to the flow velocity of the treated exhaust gas flowing into the exhaust gas outlet chamber through the strip-shaped opening in accordance with the number of surrounding exhaust gas dispersion cylinders.

In a preferred embodiment of the present invention, the exhaust gas treatment tank is formed of a box-shaped tank body having a rectangular or square cross section, and the first strip-shaped opening and the second strip-shaped opening have respective shapes. Are parallel to each other, and the side edges in the width direction are parallel to each other and extend in one direction across the tank body, and the gas riser has a hollow portion cross section having the same shape as the first band-shaped opening and the second band-shaped opening. Further, it is characterized in that an inlet duct is provided so as to introduce the exhaust gas into the exhaust gas inlet chamber in the same flow direction as the extending direction of the widthwise side edge.

The distance between the gas risers, that is, the distance between the band-shaped openings can be reduced as the distance between the band-shaped openings increases. However, regardless of the width of the gas risers, it is preferably 100 cm to 10 m. The range is more preferably 200 cm to 5 m. When the distance is 10 m or more, the flow rate per gas riser increases by that amount, the flow velocity of the treated exhaust gas increases in the space below the second partition plate, and mist is easily entrained. On the other hand, if the height is 100 cm or less, the apparatus becomes complicated and inspection and maintenance in the exhaust gas inlet chamber becomes difficult, and the construction cost increases, which is not preferable. The width of the gas riser is preferably in the range of 30 cm to 200 cm, more preferably 40 cm to 100 cm. Further, when the exhaust gas flow rate of the exhaust gas dispersion cylinder is V ₁ and the exhaust gas flow rate of the gas riser is V ₂ , V ₁ : V ₂ is 1:
It is preferably in the range of 0.2 to 2.

[0014]

In the present invention, the gas riser for communicating the space above the liquid surface of the absorbing liquid with the exhaust gas outlet chamber is arranged such that the longitudinal direction thereof coincides with the introduction direction of the exhaust gas introduced from the inlet duct into the exhaust gas inlet chamber. ing. Therefore, in the exhaust gas inlet chamber, the longitudinal direction of the gas riser coincides with the introduction direction of the exhaust gas, so the exhaust gas to be treated flows through the space between the gas riser and the gas riser without being disturbed by the gas riser and is evenly distributed. Can flow into the exhaust gas dispersion cylinder. On the other hand, in the space below the exhaust gas inlet chamber, the treated exhaust gas that has risen above the absorption liquid can flow into the nearest gas riser across the exhaust gas dispersion cylinder and enter the exhaust gas outlet chamber via the gas riser.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail based on embodiments with reference to the accompanying drawings. FIG. 1 is a plan view of a reaction tank showing a main configuration of an embodiment in which the present invention is applied to a Giotto bubbling reaction tank (hereinafter simply referred to as a reaction tank).
1 is a side sectional view of the reaction vessel taken along the line I-I in FIG. 1, and FIG.
FIG. 4 is a side sectional view of the reaction vessel taken along line II-II in FIG. 4 and FIG. 4 is a partial plan view of the second partition plate. The reaction tank 50 of this embodiment is shown in FIG.
3 to 3, it is formed of a box-shaped tank body having a rectangular cross section. As shown in FIG. 2, the reaction tank 50 is partitioned into an exhaust gas outlet chamber 52, an exhaust gas inlet chamber 54 provided so as to cross the tank body, and a lower space for accommodating the absorbing liquid in order from the top. . Exhaust gas outlet chamber 52 and exhaust gas inlet chamber 54
Is a first partition plate 56 that extends horizontally across the reaction tank 50.
The exhaust gas inlet chamber 54 and the lower space are partitioned by
It is partitioned by a second partition plate 58 extending parallel to the first partition plate 56. The second partition plate 58 is located above the liquid surface of the absorbing liquid 60, and forms a space 62 for the outflow of exhaust gas therebetween. The exhaust gas outlet chamber 52 is connected to the outlet duct 64, and the exhaust gas inlet chamber 54 thereunder is connected to the inlet duct 66 (see FIG.
And FIG. 3). The reaction tank 50 includes a top plate 68 inclined downward from the connection port with the outlet duct 64 toward the opposite side, a side plate 70 on the outlet duct 64 side, a side plate 72 facing the side plate 72, and a front plate 74 on the inlet duct 66 side. ,
It is formed of a rear plate 76 and a bottom plate 78.

In this embodiment, three gas risers 80A, 80B, 80C each having a rectangular hollow section are provided below the first partition plate 56 as means for flowing the exhaust gas from the space 62 to the exhaust gas outlet chamber 52. The exhaust gas inlet chamber 54 is penetrated to the second partition plate 58. Each gas riser 80A, B,
The Cs have the same width, and the longitudinal directions thereof are arranged in parallel with each other so as to match the exhaust gas introduction direction orthogonal to the front plate 74. As shown in FIG. 1, the gas riser 80
B is located in the center of the reaction tank 50 and is equipped with a gas riser 80A.
And 80C are arranged such that the distance to each gas riser 80B is equal to about twice the distance between the gas riser 80A and the side plate 72 or between the gas riser 80C and the side plate 70, as will be described later. The first partition plate 56 and the second partition plate 58 have the same opening periphery as the hollow section of the gas riser 80 at the joint position with the gas risers 80A, B, C.
Strip-shaped openings 82A, B, C and second strip-shaped openings 84A, B,
C are provided respectively, and the side wall of the gas riser 80 and the first
The strip-shaped opening 82 and the opening peripheral edge of the second strip-shaped opening 84 are joined.

As shown in FIG. 4, in the area other than the second strip-shaped openings 84A, B, C of the second partition plate 58, a large number of about 10 pieces are provided.
A 0 mm circular opening 86 is provided, the exhaust gas dispersion cylinder 88 descends downward from the peripheral edge of each opening 86, and is immersed in the absorbent 60 at the lower end. The openings 86 are arranged in a grid pattern having the same vertical and horizontal pitches, and when viewed in a direction parallel to the second strip-shaped openings 84, the openings 86 arranged between the second strip-shaped openings 84A and the second strip-shaped openings 84B. The number of rows is arranged to be twice the number of rows of the openings 86 arranged between the side edge on the side plate 72 side and the second band-shaped opening 84A. As a result, the exhaust gas in the vicinity of the side plate 72 and the exhaust gas in the vicinity of just the middle between the second strip openings 84A and 84B can flow into the second strip opening 84A across the same distance. In the present embodiment, the width of the second strip-shaped opening 84 is 500 mm,
Since the number n ₂ of the strip-shaped openings 84 is 3 and the total number n ₁ of the exhaust gas dispersion cylinders 88 is about 950, n ₁ / n ₂ is about 31.
6 and V _{1 is} the exhaust gas flow rate of the exhaust gas dispersion cylinder 88 and V ₂ is the exhaust gas flow rate of the gas riser 80, V ₁ : V ₂
Is 1: 0.5. The stirrer 90 has a rotary shaft 92 extending downward from a drive device 94 on the tank through the central gas riser 80B. The lower structure of the reaction tank 50 including the details of the lower end of the exhaust gas dispersion cylinder 88 is the same as the lower structure of the conventional reaction tank 10 shown in FIG.

With the structure of the gas risers 80A, 80B, and 80C, the treated exhaust gas higher than the absorption liquid 60 is treated as the space 6
It is possible to evenly disperse into the second strip-shaped opening 84 without causing severe turbulence in the second inside. Further, even if the total cross-sectional area is the same, the gas riser 84 has a remarkably large cross-sectional area per unit as compared with the conventional communication pipe having a relatively small diameter, so that the pressure loss is reduced by that much in terms of hydrodynamics. Can be suppressed. Further, in the exhaust gas inlet chamber 54, since many obstacles such as conventional communication pipes do not exist in the flow direction of the exhaust gas, the exhaust gas introduced into the exhaust gas inlet chamber 54 via the inlet duct 66 flows between the gas riser 80. Flow through the space of the exhaust gas inlet chamber 54 to the depth of the exhaust gas inlet chamber 54, and the exhaust gas dispersing cylinder 88 disposed there also has the exhaust gas dispersing cylinder 88 in front of the exhaust gas inlet chamber 54.
Can flow in the same way as.

[0019]

According to the structure of the present invention, the gas riser for communicating the space above the liquid surface of the absorbing liquid with the exhaust gas outlet chamber has its longitudinal direction in the direction of introduction of the exhaust gas introduced from the inlet duct into the exhaust gas inlet chamber. It is arranged to match. Therefore, in the exhaust gas inlet chamber, there are no obstacles such as conventional communication pipes in the exhaust gas flow direction, so the exhaust gas introduced into the exhaust gas inlet chamber through the inlet duct passes through the space between the gas riser and the gas riser. It is possible to flow to the depth of the exhaust gas inlet chamber and evenly flow into the exhaust gas dispersion cylinder arranged there. Furthermore, in the case of the conventional exhaust gas treatment tank, there are obstacles such as communication pipes, the flow of the exhaust gas in the exhaust gas inlet chamber is disturbed, and solid particles in the exhaust gas locally adhere and accumulate, causing the exhaust gas dispersion cylinder. However, such problems do not occur in the exhaust gas treatment tank according to the present invention. Further, in the space below the exhaust gas inlet chamber, the treated exhaust gas that has risen above the absorption liquid can flow into the nearest gas riser across the exhaust gas dispersion cylinder and enter the exhaust gas outlet chamber via the gas riser. Since the opening of the gas riser is large, the pressure loss is small and the exhaust gas easily flows in. Further, even if the exhaust gas flow cross-sectional area is the same as the conventional pipe-shaped communication pipe, the gas riser of the present embodiment, compared to the conventional pipe-shaped communication pipe,
Since the structure is much simpler, the amount of work at the site is significantly reduced, the construction cost can be reduced, and the maintenance is easy.

[Brief description of drawings]

FIG. 1 is a plan view of a reaction tank showing an essential configuration of an embodiment of an exhaust gas treatment tank (Jotte bubbling reaction tank) according to the present invention.

2 is a side cross-sectional view of the reaction vessel taken along the line II of FIG.

FIG. 3 is a side sectional view of the reaction vessel taken along the line II-II in FIG.

FIG. 4 is a partial plan view of a second partition plate.

FIG. 5 is a schematic view of a conventional Giotto bubbling reaction tank.

FIG. 6 is a partial plan view of a second partition plate.

[Explanation of symbols]

10 Giotto bubbling reaction tank 12, 52 Exhaust gas outlet chamber 14, 54 Exhaust gas inlet chamber 16, 56 First partition plate 18, 58 Second partition plate 20, 60 Absorbing liquid layer 22, 62 Space part 24, 64 Outlet duct 26, 66 Inlet duct 28, 80 Gas riser 30, 88 Exhaust gas dispersion pipe 32, 90 Stirrer 34 Air supply pipe 36, 92 Rotating shaft 38, 94 Drive device 40 Slurry supply pipe 42 Discharge pipe 50 Example of exhaust gas treatment tank according to the present invention (Jott) Bubbling reaction tank) 68 top plate 70, 72 side plate 74 front plate 76 rear plate 78 bottom plate 82 first belt-shaped opening 84 second belt-shaped opening 86 circular opening

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-317634 (JP, A) JP-A-8-229339 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 53/14-53/18 B01D 53/34-53/85

Claims (4)

(57) [Claims] 1. An exhaust gas treatment tank in which exhaust gas is introduced into an absorption liquid housed in the tank and brought into gas-liquid contact so that harmful substances in the exhaust gas are brought into contact with and removed by the absorption liquid. An exhaust gas outlet chamber, which is arranged in order and communicates with an outlet duct for discharging the exhaust gas, and an exhaust gas inlet which is partitioned from the exhaust gas outlet chamber by a first partition plate extending in the transverse direction of the treatment tank and which communicates with an inlet duct for introducing the exhaust gas. Chamber and a space portion partitioned from the exhaust gas inlet chamber by a second partition plate extending in the transverse direction of the treatment tank, and further having a band-shaped hollow section that penetrates the exhaust gas inlet chamber and connects the space portion and the exhaust gas outlet chamber. A gas riser having a portion and an exhaust gas dispersion cylinder that descends from the exhaust gas inlet chamber to the space portion, and the first partition plate extends along the exhaust gas introduction direction introduced from the inlet duct to the exhaust gas inlet chamber. It has Jo opening, the second
The partition plate has a second strip-shaped opening arranged at a position facing the first strip-shaped opening and a plurality of opening holes arranged in a region other than the second strip-shaped opening. The gas riser has a hollow side wall having a second side. It is provided so as to extend upward from the peripheral edge of the strip-shaped opening to reach the peripheral edge of the first strip-shaped opening that opposes, and the exhaust gas dispersion cylinder is provided so as to descend downward from the hole edge of the opening hole and be immersed in the absorbing liquid. Exhaust gas treatment tank characterized by being present. 2. The exhaust gas treatment tank is formed of a box-shaped tank body having a rectangular or square cross section, and the first strip-shaped opening and the second strip-shaped opening have the same shape, and The side edges in the width direction are parallel to each other and extend in one direction across the tank body, and the gas riser has a hollow section cross-section having the same shape as the first band-shaped opening and the second band-shaped opening. The exhaust gas treatment tank according to claim 1, wherein an inlet duct is provided so as to introduce the exhaust gas into the exhaust gas inlet chamber in the same flow direction as the extending direction of the side edge. 3. The distance between the gas risers is 10
It is in the range of 0 cm to 10 m and the width of the gas riser is 3
The exhaust gas treatment tank according to claim 2, which is in a range of 0 cm to 200 cm. 4. When the exhaust gas flow rate of the exhaust gas dispersion cylinder is V ₁ and the exhaust gas flow rate of the gas riser is V ₂ , V ₁ : V ₂ is in the range of 1: 0.2 to 2. Two
Or the exhaust gas treatment tank according to any one of 3.