JPH06170155A - Method and equipment for desulfurizing flue gas - Google Patents

Abstract

PURPOSE:To decrease running cost and the cost of equipment by utilizing air for oxidation necessary to an absorption tower and directly supplying powdery lime stone as it is to the reservoir of the absorption tower and also concentrating liquid of the absorption tower until concentration of the liquid pulled out therefrom is regulated to the specified value. CONSTITUTION:When air for oxidation necessary to an absorption tower 1 is force-fed to the reservoir 6 of the absorption tower 1 through an air supply line 14, powdery lime stone in the hopper 11 thereof is carried to the reservoir 6 on the air because the powdery lime stone supply end 12 of the hopper 11 is communicated and connected with the midway part of the air supply line 14. Powdery lime stone becomes lime stone slurry in the reservoir 6. In short, air for oxidation necessary to the absorption tower 1 can be used as a transport means of lime stone. Powdery lime stone as it is can be directly supplied to the reservoir of the absorption tower 1. Therefore an equipment of lime stone slurry is made unnecessary. Furthermore concentration of liquid pulled out from a line 15 for pulling out the liquid of the absorption tower is detected. When the concentration has been regulated to >=20%, by weight ratio, the pulled-out liquid is directly supplied to a dehydrator 18. Accordingly a thickener of gypsum is made unnecessary.

Description

Detailed Description of the Invention

The present invention relates to a desulfurization method by a wet limestone / gypsum method and an apparatus therefor.

[0002]

2. Description of the Related Art A conventional desulfurization apparatus of this type is, for example,
The configuration is as shown in FIG. In FIG.
21 is an absorption tower, 22 is a gas inlet, 23 is a gas outlet, 24
Is the bottom of the column, 25 is a liquid reservoir, 26 is an absorbing liquid (treatment liquid), 27
Is a liquid surface, 28 is an absorption liquid spray nozzle, 29 is an absorption liquid circulation pump, 30 is an absorption liquid circulation line, 31 is a limestone hopper, 32 is a rotary feeder, 33 is a limestone slurry tank,
34 is a water supply line, 35 is a stirrer, 36 is a limestone slurry pump, 37 is a limestone slurry supply line, 38 is an oxidizing air blower, 39 is an oxidizing air supply line, 40
Is an absorption tower liquid extraction line, 41 is a gypsum thickener, 42
Is an overflow line, 43 is a concentrated liquid line, 44 is a dehydrator, 45 is a filtrate line, and 46 is a recovered gypsum.

That is, in the conventional flue gas desulfurization method, the limestone powder in the limestone hopper 31 is supplied to a limestone slurry tank 33, where it is stirred with water to form a limestone slurry, which is then absorbed by a limestone slurry pump 36. It was supplied to the liquid reservoir 25 of the tower 21, and at the same time, the oxidizing air was pressurized by the oxidizing air blower 38 and supplied to the liquid reservoir 25 of the absorption tower 21.

[0004]

However, in the prior art shown in FIG. 2, means for converting limestone powder into a slurry and supplying it to the absorption tower and means for supplying oxidizing air to the absorption tower are provided. Since it was necessary for each of them, there was a problem that it was uneconomical because operating costs and equipment costs were high.

The present invention is intended to solve the above problems. That is, an object of the present invention is to provide a flue gas desulfurization method and an apparatus therefor capable of reducing operating costs and equipment costs.

[0006]

In order to achieve the above object, the flue gas desulfurization method of the present invention has an absorbent liquid spray nozzle between a gas inlet and a gas outlet and a liquid reservoir at the bottom of the tower. In a desulfurization apparatus equipped with a tower, the oxidizing air required in the absorption tower is used as a means for transporting limestone, and the limestone is supplied as a powder directly to the liquid sump of the absorption tower. The flue gas desulfurization device of No. 1 has an absorption liquid spray nozzle between a gas inlet and a gas outlet, and is a desulfurization device equipped with an absorption tower having a liquid reservoir at the bottom of the tower. It is assumed that the limestone powder supply end of the limestone hopper is connected in the middle of the air supply line for supplying air.

[0007]

According to the present invention, the oxidizing air required in the absorption tower is used as a means for transporting the limestone, and the limestone is directly supplied to the liquid reservoir of the absorption tower as a powder, so that the limestone powder is oxidized. The air for use is transported to the liquid reservoir of the absorption tower, and the limestone slurry is created in the liquid reservoir. Therefore, there is no need for conventional equipment for producing limestone slurry outside the absorption tower.

[0008]

1 shows an embodiment of a flue gas desulfurization apparatus of the present invention, which is also an apparatus for carrying out the method of the present invention. In FIG. 1, 1 is an absorption tower, 2 is a gas inlet, 3 is a gas outlet, 4 is a tower bottom, 5 is a liquid reservoir, 6 is an absorbing liquid, 7 is a liquid surface, 8
Is an absorption liquid spray nozzle, 9 is an absorption liquid circulation pump, 10
Is an absorption liquid circulation line, 11 is a limestone hopper, 12 is a limestone powder supply end, 12a is a rotary feeder, 13 is an air blower for oxidation, 14 is an air supply line, 15 is an absorption tower liquid extraction line, and 16 is a concentration detector. , 16a is a controller, 1
7 is a valve, 18 is a dehydrator, 19 is a filtrate line, and 20 is a recovered gypsum.

That is, the limestone powder supply end 12 of the limestone hopper 11 is connected in the middle of the air line 14 for supplying the oxidizing air from the oxidizing air blower 13 to the liquid reservoir 6 of the absorption tower 1. Also, the liquid extracted from the absorption tower (bleed liquid)
A concentration detector 16 provided in the middle of the absorption tower liquid withdrawing line 15 for supplying water to the dehydrator 18, and the concentration detector 16
Valve 1 provided in the middle of the line 15 on the further downstream side
7 and the controller 16a for opening the valve 17 when the concentration of the absorption tower withdrawal liquid detected by the concentration detector 16 is equal to or higher than the set concentration.

In the flue gas desulfurization apparatus constructed as shown in FIG. 1, the oxidizing air required in the absorbing tower 1 is passed from the oxidizing air blower 13 through the air supply line 14 to the absorbing tower 1
When the limestone powder supply end 12 of the limestone hopper 11 is communicatively connected in the middle of the air supply line 14, when the limestone powder in the limestone hopper 11 rides on the air, The limestone slurry is transported to the liquid reservoir 6 and becomes the limestone slurry in the liquid reservoir 6. In other words, the oxidizing air required in the absorption tower 1 can be used as a means for transporting limestone, and the limestone can be directly supplied to the liquid reservoir 6 of the absorption tower 1 as a powder. Therefore, the limestone slurry equipment that was conventionally required (in FIG. 2, the limestone slurry tank 33, the water supply line 34,
The agitator 35, the limestone slurry pump 36, and the limestone slurry supply line 37) are unnecessary.

In the prior art shown in FIG. 2, the concentration of the absorption tower withdrawal liquid is about 10% by weight, so that the gypsum thickener as a concentrating means before the absorption tower withdrawal liquid is supplied to the dehydrator 44. Although 41 is required, the flue gas desulfurization apparatus shown in FIG. 1 raises the concentration of the absorption tower extraction liquid to about 20% by weight, so that a gypsum thickener is not provided and the absorption tower extraction line is removed. It can be fed directly from 15 to the dehydrator 18.

Moreover, a concentration detector 16 is provided on the upstream side in the middle of the absorption tower liquid withdrawal line 15, a valve 17 is provided on the downstream side, and the concentration detector 1 is provided.
6 has a controller 16a for opening the valve 17 when the concentration of the liquid to be withdrawn from the absorption tower detected in 6 is a set concentration, for example, 20% by weight or more. When the concentration of the liquid extracted from the absorption tower is less than the set value by weight, the valve 17 is closed,
The liquid is not supplied to the dehydrator 18 from the withdrawal line 15, but if it exceeds a set value, the valve 17 opens and the liquid is supplied to the dehydrator 18. There is no need to provide thickener.

[0013]

As described above, according to the flue gas desulfurization method of the present invention, the absorption tower having the absorbent spray nozzle between the gas inlet and the gas outlet and the liquid reservoir at the bottom of the tower is provided. In the desulfurizer, the air for oxidation required in the absorption tower is used as a means for transporting limestone, and the limestone is directly supplied to the liquid reservoir of the absorption tower as a powder. It is transported to the liquid reservoir of the absorption tower by air, and limestone slurry is created in the liquid reservoir. Therefore,
There is no need for conventional equipment for producing limestone slurry outside the absorption tower, the equipment cost is significantly reduced, and the operating cost is also reduced.

Further, according to the flue gas desulfurization apparatus of the present invention, in the desulfurization apparatus having the absorption tower having the absorbent spray nozzle between the gas inlet and the gas outlet and having the liquid reservoir at the bottom of the tower,
Since the limestone powder supply end of the limestone hopper is connected in the middle of the air supply line for supplying the oxidizing air from the blower to the liquid reservoir of the absorption tower, the desulfurization method of the present invention is surely carried out. be able to.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view showing an embodiment of the present invention.

FIG. 2 is a partially longitudinal front view showing an example of a conventional technique.

[Explanation of symbols]

 1 Absorption Tower 2 Gas Inlet 3 Gas Outlet 4 Tower Bottom 5 Liquid Reservoir 8 Absorbing Liquid Spray Nozzle 11 Limestone Hopper 12 Limestone Powder Supply End 13 Oxidation Air Blower 14 Air Supply Line 15 Absorption Tower Liquid Extraction Line 16 Concentration Detector 16a Control Container 17 valve

Claims (4)

[Claims] 1. A desulfurization apparatus having an absorption tower having an absorbent spray nozzle between a gas inlet and a gas outlet and having a liquid reservoir at the bottom of the tower, wherein the oxidizing air required in the absorption tower is transported by limestone. A flue gas desulfurization method characterized in that the limestone is used as a means to directly supply the limestone as a powder to the liquid reservoir of the absorption tower. 2. The method of claim 1, wherein the concentration of the withdrawal liquid of the absorption tower is detected, and when the concentration becomes 20% or more by weight, the withdrawal liquid is directly supplied to the dehydrator.
Flue gas desulfurization method described. 3. A desulfurization apparatus having an absorption tower having an absorbent spray nozzle between a gas inlet and a gas outlet and having a liquid reservoir at the bottom of the tower, wherein oxidizing air is supplied from a blower to the liquid reservoir of the absorption tower. A flue gas desulfurization apparatus, characterized in that a limestone powder supply end of a limestone hopper is connected in communication with the supply air supply line. 4. A concentration detector provided in the middle of an absorption tower liquid withdrawal line for supplying the absorption tower withdrawal liquid to a dehydrator, and a concentration detector provided in the middle of the absorption tower liquid withdrawal line downstream of this concentration detector. The flue gas desulfurization apparatus according to claim 3, further comprising: a valve, and a controller that opens the valve when the concentration detected by the concentration detector is equal to or higher than a preset concentration. [Industrial applications]