JPH0857249A - Absorbing column - Google Patents

Abstract

PURPOSE: To enhance gas-liquid contact and to efficiently oxidize sulfite, in an absorbing column, wherein air is blown into a liquid storage tank storing an absorbing soln. having absorbed and removed sulfur oxide from gas to be treated to oxidize sulfite, by providing a packed bed of a packing material in the absorbing soln. CONSTITUTION: A part of the absorbing soln. 4 in a liquid storage tank 5 is transferred to spray nozzles 7 by a circulating pump 6 through a transfer pipe 8 and sprayed into an absorbing column 1 from the spray nozzles 7 and falls therein. The absorbing soln. and gas to be treated are countercurrently brought into contact with each other and sulfur oxide in the gas is absorbed by the absorbing soln. 4 and the gas to be treated is subjected to desulfurization treatment. The absorbing soln. after desulfurization treatment falls within the absorbing column to be stored in the liquid storage tank 5. Air is blown in the absorbing soln. 4 from an air blow-in port 15 to oxidize the absorbing soln. (sulfite) after desulfurization treatment. Since a packed bed 14 of a packing material 13 is provided in the way of the absorbing soln. 4, air and the absorbing soln. are brought to a sufficient contact state and the oxidation reaction of sulfite can be accelerated even if much air is not used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption tower for desulfurizing a gas to be treated such as exhaust gas from a combustion device and oxidizing a desulfurized absorption liquid.

[0002]

2. Description of the Related Art A wet flue gas desulfurization device is one of the devices for removing sulfur oxides contained in a gas to be treated such as exhaust gas from a combustion device.

This flue gas desulfurization apparatus performs desulfurization treatment of a gas to be treated by bringing the gas to be treated into contact with a slurry-like absorbing liquid containing an absorbent such as calcium carbonate or magnesium hydroxide in an absorption tower. Is. The absorption liquid is stored in a liquid storage tank in the lower part of the absorption tower, and a part of this is sprayed into the tower from a spray nozzle provided in the upper part of the tower and circulates while the gas to be treated rises in the tower. Upon contact with gas and liquid, the sulfur oxide in the gas is absorbed and removed by the absorbing liquid. The absorption liquid (sulfite) that has absorbed the sulfur oxides falls into the liquid storage tank, and a part of the absorption liquid is transferred to the oxidation tower for oxidation treatment.

[0004]

By the way, in the above-mentioned wet flue gas desulfurization apparatus, an absorption tower for desulfurizing exhaust gas and an oxidation tower for oxidizing the absorption liquid after desulfurization from the absorption tower are separately provided. Therefore, there is a problem that costs such as equipment cost and operation cost become high.

For this reason, as shown in FIGS. 4 and 5, an air blowing pipe 27 is provided in the liquid reservoir tank 26 of the absorption tower 25 to blow air directly into the absorption liquid and desulfurize in the absorption tower 25. It is possible to oxidize the absorption liquid (sulfite) after the treatment. At this time, if air is simply blown into the absorption liquid, the air rises in the absorption liquid as it is and reaches the liquid surface.
A plurality of air blowing pipes 27 are arranged in the liquid storage tank 26 of No. 5,
Air is blown from a plurality of air outlets 28 provided at predetermined intervals in the longitudinal direction of these blow pipes 27, and the tank 26
(Absorbing liquid) It has been proposed to disperse air almost uniformly over the entire surface. However, since air is blown out to the whole absorption liquid, a large amount of air is required to oxidize sulfite,
Sulfite cannot be efficiently oxidized.

Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide an absorption tower capable of efficiently oxidizing sulfite.

[0007]

In order to achieve the above-mentioned object, the present invention oxidizes sulfite by blowing air into a liquid storage tank which stores an absorbing liquid from which sulfur oxides in a gas to be treated are absorbed and removed. In the absorption tower, a packing layer filled with a packing material is provided in the absorption liquid of the liquid storage tank in order to improve gas-liquid contact.

[0008]

By providing the packed layer in the absorbent of the liquid storage tank, the air reaches the liquid surface after being sufficiently contacted with the absorbent through the packed layer, and therefore, a large amount of air is not required and sulfurous acid is not required. The oxidation reaction of the salt is promoted, and the sulfite can be efficiently oxidized.

[0009]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an absorption tower of a flue gas desulfurization apparatus for desulfurizing exhaust gas (gas to be treated) from a combustion device such as a boiler. The absorption tower 1 is formed in a vertical cylindrical shape, for example. An inlet 2 for the gas to be treated is provided on the lower side of the side portion, and an outlet 3 for the gas after desulfurization treatment is provided on the upper portion.

The absorption tower 1 is supplied with an absorption solution in the form of a slurry in which an absorption agent such as calcium carbonate or magnesium hydroxide for absorbing the sulfur content of the sulfur oxide in the gas to be treated is dissolved. The pipe 4 is connected, and a liquid storage tank 5 for storing the absorbing liquid is provided below the inside thereof. A transfer pipe 8 is connected to the liquid storage tank 5 of the absorption tower 1 to transfer a part of the absorption liquid in the tank 5 to a spray nozzle 7 provided above the tower 1 by a circulation pump 6, The absorption liquid sprayed from the spray nozzle 7 and the exhaust gas rising in the tower 1 come into countercurrent gas-liquid contact to absorb and remove the sulfur content in the gas into the absorption liquid, so that the gas to be treated is desulfurized. Therefore, the desulfurized gas is guided to the discharge port 3 after the mist is removed via the eliminator 9.

Further, below the inside of the liquid storage tank 5 of the absorption tower 1, a propeller-shaped side surface type stirring blade 10 is provided near the side wall. The stirring blade 10 is attached to a shaft 12 of a motor 11 provided through the side wall of the motor 11, and the shaft of the shaft 12 (stirring blade 10) is arranged with a predetermined angle offset from the center of the tank 5. The drive causes the stirring blade 10 to rotate to generate a discharge flow in the liquid, which causes a water flow in the circumferential direction to stir the absorbing liquid in the tank 5.

Further, a filling layer 14 is provided in the absorption liquid of the liquid storage tank 5 to be filled with a filling 13 for improving gas-liquid contact. The packing 13 may be spherical, cylindrical, Raschig ring, Lessing ring, berl saddle, or the like as long as it improves gas-liquid contact. For example, the spherical shape may be hollow, and the diameter thereof is preferably about 20 to 100 mm. The material of the filler 13 is a material having a smaller specific gravity than the absorbing liquid and can be moved by the water flow of the stirring blade 10, and examples thereof include polypropylene and vinyl chloride. Since the filling material is formed of a material having a smaller specific gravity than the absorbing liquid such as polypropylene, it floats in the absorbing liquid. Therefore, if the filling material 13 is floated by a predetermined number, the filling layer 14 at a predetermined distance from the liquid surface is formed. It is formed.

The height (layer thickness) of the filling layer 14 is arbitrarily determined as long as gas-liquid contact is sufficiently performed. For example, when the diameter of the absorption tower 1 (liquid reservoir tank 5) is 10 m and the height of the liquid surface of the tank 5 is about 7 to 8 m, the layer thickness of the packed bed 14 is 50 to 10
It is preferably 0 cm. This is because if it is less than 50 cm, gas-liquid contact is not sufficiently performed, and if it exceeds 100 cm, a significant improvement in efficiency cannot be expected. As a specific example, the filling layer 14 is formed by filling polypropylene spheres (filling material) having a diameter of 38 mm with the absorbing liquid in the liquid storage tank 5 about 50 cm from the liquid surface.

Further, below the filling layer 14 of the liquid storage tank 5, an air blowing port 15 is provided at a predetermined interval in the circumferential direction.
4 or more are provided, and the air blowing port 15 is formed so as to blow out air in a tangential direction. Air inlet 1
No. 5 is, for example, 90 ° because the air blown into the absorbing liquid reaches the liquid surface through the packed bed 14 and makes sufficient contact with the absorbing liquid.
About four intervals are sufficient.

Next, the operation of this embodiment will be described.

Exhaust gas (gas to be treated) is introduced into the absorption tower 1 through the inlet 2 and rises in the tower 1. This absorption tower 1
A slurry-like absorbing liquid in which an absorbing agent such as calcium carbonate is dissolved is introduced into the liquid from the absorbing liquid supply pipe 4, and the liquid collecting tank 5
Accumulate inside. A part of it is transferred to the spray nozzle 7 through the transfer pipe 8 by the circulation pump 6, and sprayed and dropped from the nozzle 7 into the tower 1. The absorption liquid and the gas come into countercurrent contact with each other, the sulfur oxide in the gas is absorbed by the absorption liquid, and the gas to be treated is desulfurized. The desulfurized gas has its mist removed via the eliminator 9, reaches the discharge port 3, and is then introduced to another system.

After the desulfurization treatment, the absorbing liquid drops in the tower 1 and collects in the liquid tank 5. This absorption liquid has an air inlet 15
Air is blown into the absorbent, and the desulfurized absorption liquid (sulfite) is oxidized. At this time, since the absorbing liquid is filled with the filling material, for example, the spherical filling material 13 and the filling layer 14 is provided, the air and the absorbing liquid are sufficiently in contact with each other. The salt oxidation reaction can be accelerated.
For example, when a polypropylene hollow sphere (filler) 13 having a diameter of 38 mm is filled in the absorbing liquid of the liquid storage tank 5 by about 50 cm from the liquid surface to form a filling layer 14, an air blowing port 15 for blowing air in a tangential direction. Even if there are about 4 points, the air and the absorbing solution are in sufficient contact. Further, since the number of air inlets is smaller than that in the case where the air is substantially evenly distributed over the entire surface of the tank 5, maintenance is facilitated and there is an economic effect.

Further, when the stirring blade 10 is rotationally driven by the motor 11, the liquid on the back surface (suction side) of the blade 10 is pushed out in front of the blade to generate a discharge flow, and the discharge flow is generated in the tank 5 in the circumferential direction. A stream of water is created and the absorbent is stirred. As a result, air can be dispersed in the absorbing liquid, and uniform oxidation reaction can be promoted. Further, it is possible to prevent SS from settling in the absorbent. Further, the filler 13 is polypropylene,
When the filler 13 is made of a material having a smaller specific gravity than the absorbing liquid such as vinyl chloride, the filler 13 floats in the absorbing liquid, and is freely moved by the water flow by the stirring blades 10, so that the air dispersion is improved and the gas-liquid mixture is improved. The contact becomes more effective. Also,
The solid content is prevented from being clogged in the filling material 13, and the gas-liquid contact effect in the filling layer 14 is sufficiently exerted.

Therefore, by providing the filling layer 14 in the absorbing liquid, the sulfite can be efficiently oxidized.

FIG. 2 is a diagram showing a modification of the first embodiment. The difference from the first embodiment is that the filling layer 14 is formed at an arbitrary position in the absorbent. That is, as shown in the drawing, a net (for example, a wire net 16) having a coarse mesh (to the extent that the filler 13 does not pass) is stretched at a predetermined position in the absorbent, and the filler 13 is filled under the wire net 16. To form the filling layer 14. Even if the packing layer 14 is provided in the middle of the absorbing solution as described above, the absorbing solution (sulfite) obtained by the desulfurization treatment has substantially the same function and effect as the above embodiment.
Can be efficiently oxidized. The wire net 17 below the filling layer 14 may or may not be provided, but by providing it, it is possible to suppress the bias of the filling 13 due to a water flow or the like.

FIG. 3 is a view showing a second embodiment. The difference from the above-mentioned embodiment is that the filling material 18 has a specific gravity larger than that of the absorbing liquid and is made of a material such as glass which can be moved by the water flow of the stirring blade 10. Is. That is, as shown in the figure, a net having a coarse mesh, for example, a wire net 19 is stretched at a predetermined position in the absorbent, and a glass filler 18 is filled on the wire net 19 to form a filling layer 20. Even if the filling layer 20 is provided in this way, the same effects and advantages as in the above-described embodiment can be obtained, and the sulfite can be efficiently oxidized. Further, the wire net 21 above the filling layer 20 may or may not be provided, but by providing it, it is possible to suppress the bias of the filling material 18 due to a water flow or the like.

[0023]

In summary, according to the present invention, since the filling layer is provided in the absorbing liquid of the liquid storage tank, the excellent effect that the sulfite can be efficiently oxidized is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a modification of the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing an example of an absorption tower proposed previously.

5 is a view taken along the line AA in FIG.

[Explanation of symbols]

 5 Liquid Storage Tank 13 Packing Material 14 Packing Bed

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B01D 53/34 ZAB B01D 53/34 125 D 125 E

Claims (1)

[Claims] 1. An absorption tower which oxidizes sulfite by injecting air into a liquid storage tank for storing an absorption liquid in which a sulfur oxide in a gas to be treated is absorbed and removed, and a gas-liquid mixture is contained in the absorption liquid in the liquid storage tank. An absorption tower provided with a packed bed filled with a packing material for improving contact.