JPH11137957A - Desulfurizer for stack gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desulfurizer for stack gas capable of remarkably decreasing the pieces of pipelines equipped in an absorption column and attaining further simplification of the whole equipment. SOLUTION: In the desulfurizer for stack gas for performing the reaction and absorption of sulfur dioxide in a waste gas by forcibly feeding the waste gas while forcibly feeding a gas for oxidation into an absorbing solution stored in the absorption column to allow to gas-liquid contact, the absorbing solution and the air for oxidation are supplied to the absorption column through the same pipe line 28 used for each other by connecting a supply pipe 22 for replenishing the absorbing solution to the absorption column to a supply pipe 21, for forcibly supplying the gas for oxidation to the absorption column.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for reacting sulfur dioxide gas in an exhaust gas by bringing the exhaust gas containing the sulfur dioxide gas into contact with an absorbing solution comprising a sulfur dioxide neutralizing agent slurry solution in an absorption tower. The present invention relates to a flue gas desulfurization unit that absorbs gas.

[0002]

2. Description of the Related Art Conventionally, as one type of flue gas desulfurization apparatus for detoxifying a large amount of exhaust gas generated in a boiler or the like of a thermal power plant, sulfur dioxide gas (SO ₂ ) contained in exhaust gas is converted to limestone (CaCO ₃ ). It is widely known that a gas is brought into gas-liquid contact with an absorbing solution consisting of an aqueous solution (sulfurous acid gas neutralizing agent slurry solution) in which is dissolved or suspended, thereby absorbing and removing the same in the absorbing solution.

FIG. 3 shows the structure of a main part of a conventional flue gas desulfurization apparatus of this type. An absorption tower 1, which is a main part of the flue gas desulfurization apparatus, has a circular or square horizontal section, and an upper deck 3 and a lower deck 2 are arranged in an upper space at an interval in the vertical direction. ing. These decks 3 and 2 are provided as partition walls for airtightly defining the internal space of the absorption tower 1. The lower space of the lower deck 2 is a storage tank 4, and the space between the upper deck 3 and the lower deck 2 is an entrance. The plenum 6 and the upper space of the upper deck 3 form an exit plenum 8. In the storage tank 4, an absorption liquid K made of limestone slurry is stored at a predetermined level. The inlet plenum 6 is connected to an inlet duct 5 for introducing exhaust gas into the absorption tower 1, while the outlet plenum 8 is connected to an outlet duct 7 for leading treated exhaust gas from the absorption tower 1 to the outside. ing.

A number of openings are formed in the lower deck 2 in a distributed manner, and each opening is connected to an upper end of a sparger pipe (exhaust gas introducing pipe) 9 hanging down from the lower surface of the lower deck 2. ing. The sparger pipe 9 has a lower end inserted into the absorbent K in the storage tank 4, and an exhaust gas discharge hole 9a formed in the outer periphery of the lower end in a horizontal direction. The exhaust gas discharge hole 9a is opened at a predetermined depth below the liquid level of the absorbing liquid K, and discharges exhaust gas horizontally below the liquid level of the absorbing liquid K.

A gas riser 10 is provided between the lower deck 2 and the upper deck 3 so as to communicate an upper space 4 a above the absorbent surface of the storage tank 4 with the outlet plenum 8 so as to penetrate the inlet plenum 6. Have been. Further, at the bottom of the storage tank 4, a supply pipe 11 for oxidizing air for blowing out oxidizing air (oxidizing gas) and a stirrer 12 for stirring the absorbing liquid K are provided. The end side is connected to a blower 15 for pumping oxidizing air. A slurry pump 13 is connected to the storage tank 4. Further, a supply pipe 14 for supplying limestone slurry (neutralizing agent slurry) into the absorption tower 1 is connected to the absorption tower 1. The proximal end of the supply pipe 14 is connected to a liquid pump (not shown) that is a pressure supply source of the absorbing liquid. Further, the absorption tower 1 is provided with a supply pipe for returning the mother liquor after removing gypsum (sulfate) generated from the absorption liquid K extracted by the slurry pump 13 back into the absorption tower 1, and the absorption pipe. A circulation supply line for circulating the absorption liquid K in the tower 1 is provided.

In the absorption tower 1 having the above structure,
When supplying exhaust gas from the inlet duct 5 to the inlet plenum 6 while supplying oxygen into the absorbing liquid K through the supply pipe 11,
The exhaust gas is ejected from the ejection holes 9a at the lower end of each sparger pipe 9, and vigorously mixes with the absorbing liquid K to form a liquid phase continuous jet bubbling layer. At this time, the stirrer 1
2 to stir the absorbing liquid K and supply pipe 1
The oxidizing air supplied from 1 is continuously supplied into the absorbing liquid K from the nozzle at the tip. Thereby, highly efficient gas-liquid contact is performed in the jet bubbling layer, and SO ₂ + CaCO ₃ +1/2 O ₂ + H ₂ O → CaSO _4.
As shown by 2H ₂ O ↓ + CO ₂硫酸, sulfurous acid gas (S
O ₂ ) is oxidized and a reaction neutralized by the limestone in the absorbing solution K is performed, whereby the sulfur dioxide gas is absorbed and removed. The desulfurized and detoxified exhaust gas is discharged from the gas riser 10 through the outlet plenum 8 and the outlet duct 7 to the outside through the chimney.

On the other hand, gypsum (CaSO ₄₎ formed in the absorbing solution by oxidizing and neutralizing sulfurous acid gas (SO ₂ )
2H ₂ O) · becomes a absorbing liquid gypsum slurry by coarse particles by being grown, upon reaching a predetermined concentration, it is withdrawn from the reservoir 1 by the slurry pump 13, to the mother liquor and plaster Separated. The mother liquor is mixed with a new liquid and stored in the slurry tank 21 as a replenishing absorbing liquid. Then, in accordance with the output of the level meter 20, a replenishing absorbent is supplied into the absorption tower 1 through the supply line.

According to the flue gas desulfurization apparatus using such an absorption tower 1, the stirrer 1 is supplied while oxidizing air is supplied into the absorbing solution.
2 and the exhaust gas is blown out from the lower end of each sparger pipe 9 to form a jet bubbling layer that is continuous with the absorbing liquid, so that sulfur dioxide gas (SO ₂ ) in the exhaust gas is absorbed and oxidized. -The entire process of neutralization and gypsum crystallization can be performed in one tank, and there is an advantage that sulfur dioxide gas can be removed with extremely high efficiency.

[0009]

In the above-mentioned conventional flue gas desulfurization apparatus, the sulfur dioxide gas and the absorbent are brought into gas-liquid contact with high efficiency in the jet bubbling layer to react with each other. It is necessary to supply the air and the absorbing liquid to be dispersed uniformly over the entire area of the storage tank 4 in the horizontal plane. For this reason, in the absorption tower 1, the supply pipe 11 for the oxidizing air and the supply pipe 14 for the absorption liquid are branched into a number of branch pipes inside the storage tank 4 and extended to various places in the horizontal plane. By piercing a plurality of ejection nozzles at predetermined intervals in each branch pipe, the oxidizing air and the limestone slurry to be replenished as much as possible, and the absorbing liquid circulated and supplied into the absorption tower 1 are all over the horizontal plane of the storage tank 4. It is designed to be evenly distributed over

For this reason, at the bottom of the absorption tower 1, a large number of branch pipes from the supply pipe 11 for oxidizing air, branch pipes from the supply pipe 14 for limestone slurry, and supports for supporting these branch pipes are provided. Because of the crossing, the structure becomes complicated, and the construction of these pipes requires a lot of trouble, and the crossed branch pipes and their supports are often used for maintenance inspection and cleaning of the bottom part. There was a problem that time was required. In addition, since the inside of the storage tank 4 is in an atmosphere of metal corrosion, metal materials such as a large number of branch pipes and supports described above and bolts and nuts for mounting are replaced with expensive metal having excellent corrosion resistance. , Or a treatment such as applying a coating for corrosion resistance to the surface is required, which has generally contributed to an increase in equipment costs.

The present invention has been made in order to effectively solve the problems of the above-mentioned conventional flue gas desulfurization apparatus, and can greatly reduce the number of pipes installed in the absorption tower. It is an object of the present invention to provide a flue gas desulfurization device capable of achieving further simplification.

[0012]

According to a first aspect of the present invention, there is provided a flue gas desulfurization apparatus comprising: an absorbing liquid stored in an absorption tower;
In a flue gas desulfurization device that reacts and absorbs sulfurous acid gas in exhaust gas by pumping the oxidizing gas and bringing the exhaust gas into gas-liquid contact, a supply pipe that circulates or replenishes the absorbing solution into the absorption tower, The absorption liquid and the oxidizing gas are supplied into the absorption tower by connecting the supply pipe for pumping the oxidizing gas into the absorption tower by the same pipe which also serves as the absorption liquid. It is.
Here, the absorbing liquid referred to in claim 1 is the absorbing liquid itself circulated and supplied into the absorption tower, or is replenished to the absorbing liquid in the absorption tower after the sulfate is extracted from the absorption tower and the sulfate is separated. And a neutralizing agent slurry to be supplied to the mother liquor or the absorbing solution in the absorbing tower. According to a second aspect of the present invention, the absorbent according to the first aspect is a neutralizing agent slurry to be supplied to the absorbent.

Further, in the invention described in claim 1 or 2, in the invention described in claim 3, the supply pipe for the absorbing liquid is connected in a direction intersecting the extending direction of the supply pipe for the oxidizing gas. By utilizing the ejector effect of the oxidizing gas, the oxidizing gas and the absorbing liquid are mixed and supplied into the absorption tower in the same pipe, The invention according to claim 4 is that, by forming a reduced-diameter portion in the supply pipe for the oxidizing gas and connecting the supply pipe for the absorbing solution to the reduced-diameter section, the same pipe is formed in the same pipe by a venturi effect. An oxidizing gas and an absorbing liquid are mixed and supplied to the absorption tower.

In the invention according to any one of claims 1 to 4, the absorption liquid and the oxidizing gas are supplied into the absorption tower through the same common pipe by connecting the supply pipes to each other. As a result, the number of pipes in the absorption tower can be reduced to about half of the conventional one. As a result, in particular, the structure at the bottom of the absorption tower is simplified, pipes and their supports are easily installed, and maintenance and inspection and cleaning at the bottom of the absorption tower are further facilitated. Also,
By reducing the number of pipes, a significant reduction in equipment cost can be achieved.

In particular, in the invention according to any one of claims 2 to 4, the oxidizing gas and the neutralizing agent slurry are mixed in the same pipe by utilizing the Venturi effect by the oxidizing gas. And can be supplied into the absorption tower. As a result, the supply of the oxidizing gas and the neutralizer slurry becomes smoother, and the two can be uniformly mixed and dispersed / supplied from all the ejection nozzles over the entire area. When the pH is obtained, the desulfurization efficiency can be improved. In addition, since the bubbles of the oxidizing air become finer, the oxidation efficiency is increased and the generation of scale can be prevented.

In particular, in the invention according to claim 4,
Since the absorbing liquid is introduced into the high-speed and low-pressure oxidizing gas in the reduced diameter portion, the absorbing liquid is finely divided by the high-speed oxidizing gas, and the absorption liquid and the oxidized gas reduced in the enlarged diameter portion When the relative velocity with the working gas increases and the particles collide with each other, the oxidizing gas and the absorbing liquid can be supplied from the ejection nozzle in a more uniform mixed fluid, which is preferable. .

[0017]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same components as those of the conventional example shown in FIG. FIG. 1 is a system diagram schematically showing a main part configuration of an embodiment of a flue gas desulfurization apparatus according to the present invention. In this flue gas desulfurization device, a supply pipe 21 for oxidizing air whose base end is connected to a pressure blower (not shown) is disposed horizontally above the absorption tower 1 and extends vertically. It is inserted into the lower part of the storage tank 4 via 23. A horizontal distribution pipe 24 (only one of which is shown in the drawing) is branched at the lower end of the hanging pipe 23 and extends over the entire bottom of the absorption tower 1. The ejection nozzle 25 is attached downward. Oxidizing air can be ejected into the absorbing liquid K from the tips of the ejection nozzles 25.

A supply pipe 22 of limestone slurry (neutralizing agent slurry) vertically merges with a horizontal portion of the oxidation air supply pipe 21 on the inlet side of the absorption tower 1 from above. A further downstream side is a supply pipe (same pipe) 28 that also serves as a supply pipe for the oxidizing air and a supply pipe for the neutralizing agent slurry. Here, at the junction X, as shown in FIG. 2, a reduced diameter portion 21a is formed in the supply pipe 21 for the oxidizing air, and the supply pipe 22 for the limestone slurry is connected to the reduced diameter portion 21. Have been. Thus, the limestone slurry to be replenished is supplied to the supply line 28 by the Venturi effect due to the change in the flow rate of the oxidizing air.
Inside, it is mixed with the oxidizing air and supplied to the absorption tower 1.

Next, the operation of the flue gas desulfurization apparatus having the above configuration will be described. First, during the operation of the flue gas desulfurization apparatus, the supply pipe 21 is supplied with oxidizing air by a blower. Then, when the pH in the storage tank 4 changes with the progress of the operation and it becomes necessary to replenish the limestone slurry, the limestone slurry is injected from the supply pipe 22. On the other hand, the oxidizing air in the supply pipe 21 becomes high-speed and low-pressure in the reduced diameter portion 21a.
The limestone slurry supplied from 2 is sucked by the flow of the oxidizing air, is fined, and is sent to the enlarged diameter portion 21b on the supply pipe 28 side. Then, when the flow rate of the oxidizing air decreases again at the enlarged diameter portion 21b,
When the relative speed between the limestone slurry and the decelerated oxidizing air increases and the particles collide with each other, the oxidizing air and the finely divided absorbent are mixed uniformly, and are horizontally mixed from the supply pipe 28. Sent to the distribution pipe 24,
5 is supplied into the absorbing liquid in the storage tank 4.

As described above, according to the flue gas desulfurization apparatus,
The limestone slurry and the oxidizing air are supplied to each other in a supply pipe 21,
By connecting 22, the water is supplied into the absorption tower 1 via the shared supply pipe 28, so that the horizontal distribution pipe 24 in the absorption tower 1 can be reduced to about half of the conventional one. Therefore, the structure at the bottom of the absorption tower 1 is further simplified, the construction of the horizontal distribution pipe 24 and its support is facilitated, and the maintenance and inspection and cleaning at the bottom of the absorption tower 1 are further facilitated. By reducing the number of pipes at the bottom of the absorption tower 1, a significant reduction in equipment cost can also be achieved.

In addition, a reduced diameter portion 21a is formed in the today's space 21 for the oxidizing air, and the supply pipe 22 for the limestone slurry absorbing liquid is connected to the reduced diameter portion 21a.
The oxidation air and the limestone slurry can be uniformly mixed and supplied into the absorption tower 1 by utilizing the Venturi effect of the oxidation air flowing in the inside, so that the supply of the oxidation air and the limestone slurry is further increased. In addition to being smooth, both can be uniformly mixed and dispersed and supplied from each ejection nozzle 25 over the entire area of the storage tank 4. In addition, the bubbles of the oxidizing air become finer, so that the oxidizing efficiency increases and the generation of scale can be prevented.

In the above embodiment, only the case where the oxidizing air and the limestone slurry to be supplied to the absorbing solution are supplied into the absorption tower 1 through the same supply pipe 28 has been described. However, the present invention is not limited to this, and can be applied to supply of a mother liquor to be supplied into the absorption tower 1 or an absorption liquid circulated in the absorption tower 1 as described above. Further, as the oxidizing gas, only the case where oxidizing air is used has been described, but the present invention is not limited to this, and the same applies to the case where another oxygen-containing gas is used. It is.

[0023]

As described above, according to the present invention, the absorbing liquid and the oxidizing gas are supplied into the absorption tower through the same common pipe. The piping in the absorption tower can be reduced to about half that of the conventional one, thereby simplifying the structure at the bottom of the absorption tower, facilitating the construction of the piping and its support, etc., and at the bottom of the absorption tower. Maintenance inspections, cleaning, and the like are further facilitated, and the reduction in the number of pipes can also achieve a significant reduction in equipment costs.

According to the invention of any one of claims 2 to 4, the supply of the oxidizing gas and the absorbing solution can be further smoothly performed by utilizing the Venturi effect and the like by the oxidizing gas. Both can be uniformly mixed and dispersed and supplied from each ejection nozzle over the entire area in the absorption tower.Also, since the bubbles of the oxidizing air become finer, the oxidation efficiency increases and the generation of scale is reduced. The effect that can be prevented is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic system configuration diagram of an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing a connection part of a supply pipe of FIG.

FIG. 3 is a system configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Absorption tower 21 Supply pipe of oxidizing air (oxidizing gas) 21a Reduced diameter part 22 Supply pipe of limestone slurry (neutralizing agent slurry) 24 Horizontal distribution pipe 25 Spout nozzle 28 Supply pipe (same pipe)

Claims (4)

[Claims] 1. A flue gas desulfurization device that reacts and absorbs sulfurous acid gas in exhaust gas by pumping an oxidizing gas into the absorbing solution stored in the absorption tower and ejecting the exhaust gas to make gas-liquid contact. A supply pipe for circulating or replenishing the absorption liquid into the absorption tower,
By connecting a supply pipe for feeding the oxidizing gas into the absorption tower by pressure, the absorption liquid and the oxidizing gas are supplied into the absorption tower by the same piping that also serves as the absorption pipe. Flue gas desulfurization equipment. 2. The flue gas desulfurization apparatus according to claim 1, wherein said absorbing liquid is a neutralizing agent slurry to be supplied to said absorbing liquid. 3. The oxidizing gas and the absorbing liquid are mixed in the same pipe by connecting the absorbing liquid supplying pipe in a direction intersecting with the extending direction of the oxidizing gas supplying pipe. 3. The flue gas desulfurization apparatus according to claim 1, wherein the flue gas is supplied into the absorption tower. 4. An oxidizing gas supply pipe is formed with a reduced diameter portion, and the absorbing liquid supply pipe is connected to the reduced diameter portion, so that the oxidizing gas and the oxidizing gas are absorbed in the same pipe by a Venturi effect. 3. The flue gas desulfurization apparatus according to claim 1, wherein the liquid is mixed and supplied into the absorption tower.