JP2003181241A - Wet-type flue gas desulfurization apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet-type flue gas desulfurization apparatus which is compact, has high reliability, is able to suppress the generation of a foamy layer, and can be stably operated. <P>SOLUTION: The wet-type flue gas desulfurization apparatus has an absorption column for desulfurizing by bringing an exhaust gas containing sulfur oxides into contact with a calcium-based absorbing solution, and a circulation tank 6 which is provided at the lower part of the absorption column and stores the absorbing solution used for cleaning treatment of the exhaust gas at the absorption column. In the wet- type flue gas desulfurization apparatus, the solution falling in the circulation tank 6 along the wall surface of the absorption column is recovered with a solution recovering section 18 (trough for recovering the solution) provided at the wall surface of the circulation tank, and the recovered solution is rapidly pored into the solution in the circulation tank from the solution recovering section 18, thereby flowing down of the absorbing solution onto the surface of the solution in the circulation tank along the wall surface of the circulation tank is avoided and the engulfing of the gas in the column during this time is completely suppressed. Accordingly, the generation of the foamy layer at the surface of the solution in the circulation tank is prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet flue gas desulfurization device for removing sulfur dioxide (SO ₂ ) in exhaust gas discharged from a combustion device such as a boiler, and more particularly to a foam layer formed on the liquid surface of a circulation tank. It is about reduction.

[0002]

2. Description of the Related Art Sulfur oxides, especially sulfur dioxide (SO ₂ ) in flue gas generated by combustion of fossil fuels in thermal power plants, etc., is a main cause of environmental problems such as air pollution and acid rain. one of. The flue gas desulfurization system that removes the sulfur oxides in the flue gas is dominated by the wet method using the limestone-gypsum method. Among them, the most proven and highly reliable spray method is widely adopted worldwide. . However, due to diversification of fuel, reduction of wastewater, etc., severe operating conditions for flue gas desulfurization equipment have come to be required.
To maintain desulfurization performance and prevent troubles,
Further advanced technology development is required.

As a known example of a wet type flue gas desulfurization apparatus adopting a spray method of the prior art, a side view of an absorption tower constituting a desulfurization apparatus is shown in FIG. This wet flue gas desulfurization apparatus mainly comprises an absorption tower body 1, an inlet duct 2, an outlet duct 3, an absorbent circulating pump 4, a circulation tank 6, an agitator 7, an air supply pipe 8,
It is composed of a mist eliminator 9, an absorbent extraction pipe 10, a circulation pipe 11, a spray header 12, a spray nozzle 13, a suction pipe 14, and the like.

Exhaust gas discharged from the boiler is introduced into the absorption tower body 1 from the inlet duct 2 and discharged from the outlet duct 3 provided at the top of the tower. During this period, the absorption liquid 5 containing calcium carbonate sent from the absorption liquid circulation pump 4 is sprayed from the spray nozzle 13, and the absorption liquid 5 and the exhaust gas are brought into gas-liquid contact. At this time, the absorbing liquid 5 absorbs the sulfur oxide (SO ₂ ) in the exhaust gas and produces sulfite ion (SO ₃ ²⁻ ). The absorption liquid 5 is temporarily stored in the circulation tank 6, and while being stirred by the oxidation stirrer 7, calcium sulfite Ca (HSO ₃ ) ₂ is oxidized by oxygen in the air supplied from the air supply pipe 8, and calcium sulfate (gypsum) To generate. At this time, since the oxidizing air is supplied from behind the impeller of the stirrer, it becomes fine bubbles, and the oxidizing efficiency is enhanced.

On the other hand, in the circulation tank 6, a foam layer 16 which is fine bubbles is formed in addition to the oxidizing air. Foam layer 1
The absorbing liquid 6 that falls into the circulation tank 6 collides with the liquid surface, so that the exhaust gas in the absorption tower is entrained in the liquid in the tank and is generated. Therefore, the absorbing liquid 5 in the circulation tank 6 contains air bubbles of oxidizing air and fine air bubbles of the foam layer 16. These bubbles cause the bubbles to be sucked into the absorbent circulating pump 4 and the hold-up amount to increase. this house,
Since the fine bubbles forming the foam layer 16 are mainly composed of the gas in the absorption tower, there is almost no oxygen in the bubbles.
It does not contribute to the oxidation of SO ₃ ^2- . On the other hand, the foam layer 16
The fine bubbles inside are sucked into the circulation pump 4 to reduce the amount of circulating liquid and increase (hold up) the liquid level.

[0006]

In the above prior art, the suction of air bubbles into the circulation pump 4 is performed by the absorption liquid circulation pump.
Suction pipe 1 opened on the wall of circulation tank 6 equipped with 4
It is prevented by a baffle plate 17 which surrounds the connection part of No. 4, but is not considered with respect to the hold-up. When the hold-up amount increases and the liquid level in the circulation tank 6 rises, a backflow of the absorbing liquid 5 to the inlet duct 2 occurs, so that the circulation tank 6 does not retain the liquid even if the hold-up amount due to the fine bubbles is added. It is designed to have a tank capacity that does not reach the level where the inlet duct 2 is installed. The hold-up amount varies depending on the type of the absorbing liquid 5, but may increase by 20 to 40% of the liquid amount in the circulation tank 6.

In the above-mentioned prior art, the generation of the foam layer 16 has not been sufficiently taken into consideration, and it has been necessary to secure an unnecessarily large capacity of the circulation tank 6.

The object of the present invention is to suppress the formation of a foam layer,
It is to provide a wet type flue gas desulfurization device that is compact, reliable, and capable of stable operation.

[0009]

The above object of the present invention is to provide an inlet duct for introducing a sulfur oxide-containing exhaust gas discharged from a combustion device such as a boiler, an exhaust gas introduced from the inlet duct, and a calcium-based absorbent. It was used for purification processing of exhaust gas in the absorption tower provided with an absorption part provided with a gas-liquid contact area to be brought into contact and an outlet duct for discharging the exhaust gas purified by the absorption part, and in the lower part of the absorption tower in the absorption tower. In a wet flue gas desulfurization device having a circulation tank for storing the absorption liquid and an absorption liquid circulation system for supplying a part of the absorption liquid in the circulation tank to the gas-liquid contact region of the absorption tower, the wall surface of the absorption tower A tub-shaped liquid recovery unit is provided on the wall surface of the circulation tank to collect the liquid that has traveled through the tank and drops into the circulation tank, and then pour the collected liquid into the circulation tank to reduce the drop distance to the liquid surface of the circulation tank. Wet flue gas desulfurization It is solved by location.

The liquid that drops along the tower wall of the absorption tower into the circulation tank is prevented from once being collected by the liquid collection unit and directly flowing into the liquid surface in the circulation tank, and is circulated promptly from the liquid collection unit. By pouring the recovered liquid into the liquid in the tank,
It is possible to prevent the gas in the absorption tower from being entrained by the absorption liquid propagating through the tower wall, and suppress the formation of a foam layer on the liquid level in the circulation tank.

The liquid recovery section is provided with a liquid recovery gutter having an inclined surface with respect to the horizontal, which is installed over a part or the whole of the inner surface of the side wall of the circulation tank, and the liquid recovery gutter. By connecting the liquid discharge pipe with the outlet at the lower end immersed in the liquid of the circulation tank to the lowest part of the inclined surface of, the absorbing liquid flowing along the wall surface of the circulation tank and flowing down to the liquid surface of the circulation tank is eliminated, It is possible to more effectively suppress the formation of a foam layer on the liquid level in the circulation tank by eliminating the entrainment of gas in the inside.

When the absorbing liquid collected in the liquid collecting section is discharged vertically downward from the liquid discharge pipe, a strong downward flow is generated near the outlet of the discharge pipe, and depending on the liquid flow in the circulation tank, Since the flow of the absorbing liquid is directly sucked into the absorbing liquid circulation system, the residence time of the liquid discharged from the liquid discharge pipe may be insufficient for the oxidation of sulfite ion (SO ₃ ²⁻ ). In order to prevent this, the outlet of the liquid discharge pipe can be oriented in the horizontal direction to prevent the downward flow.

As a liquid recovery section, a liquid recovery gutter (such as the liquid shield plate 20 in FIG. 6) is provided on the inner wall surface of the absorption tower above the inlet duct, and the liquid recovery gutter provided from the gutter to the circulation tank wall surface. With the configuration in which the liquid discharge pipe for discharging the collected liquid is connected to
Of the absorbing liquid flowing down the tower wall of the absorption tower, there is no liquid falling through the opening connected to the inlet duct, so that no pressure loss occurs in the exhaust gas flow introduced from the inlet duct. Further, since the droplet-shaped absorbing liquid is collected on the inner wall surface of the absorption tower by the liquid collecting gutter (such as the liquid shielding plate 20 in FIG. 6) and the liquid collecting unit and is poured into the circulation tank, the foam layer is not generated. Suppressed.

Further, the lower end outlet of the liquid discharge pipe is provided at a position distant from the circulation tank connection part of the absorption liquid circulation system for supplying a part of the absorption liquid in the circulation tank to the gas-liquid contact region of the absorption tower. You can

The liquid recovered by the liquid recovery unit contains a small amount of air bubbles having a low oxygen content, and the recovered liquid is discharged from a position distant from the circulation tank connection part of the absorption liquid circulation system through a liquid discharge pipe. When poured into the absorption liquid in the circulation tank via
The recovery liquid containing bubbles having a low oxygen content is less likely to enter the circulation tank of the absorption liquid circulation system directly from the liquid discharge pipe, and the desulfurization rate is not adversely affected.

Further, since the gas in the tower may be mixed with the liquid flowing into the circulation tank from the liquid discharge pipe,
If a temporary storage part for the recovered liquid is provided at the connection part of the liquid discharge pipe with the liquid recovery gutter, the liquid recovered in the liquid recovery part will temporarily accumulate in the liquid storage part, so that the gas in the tower together with the liquid. Can be prevented from flowing into the liquid in the circulation tank.

The liquid collecting trough according to the present invention may have a structure including a side wall surface, a bottom surface and a balustrade of the circulation tank or a structure in which the wall surface of the circulation tank and a flat plate are connected in an inverted triangular cross section.

Since the liquid recovery gutter having an inverted triangular vertical section and having no bottom is relatively simple in structure, the cost is lower than that of the liquid recovery gutter composed of the side wall of the circulation tank, the bottom and the balustrade.

Further, the liquid collecting trough is divided into two or more parts along the entire circumference of the wall surface of the circulation tank, and both ends of each of the divided gutters are vertically aligned with both ends of the other gutter. The configuration may be such that they are arranged at overlapping positions.

In this case, since the two end portions of the liquid recovery section, which is divided into two or more parts as viewed in the vertical direction of the tower wall surface, are arranged at positions where the both ends partially overlap, the liquid recovery section is more compact in the vertical direction. It becomes a composition.

The liquid collecting trough may have a structure in which the lowest part of the inclined surface of the liquid collecting trough is immersed in the liquid in the circulation tank. In this case, it is not necessary to provide a liquid discharge pipe.

Further, the liquid collecting tub in this case can reduce the flow-down speed of the absorbing liquid flowing down the wall at the same time when the liquid is collected. And lower it to the tank surface. This has the effect of reducing gas entrainment and reducing the foam layer.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a wet flue gas desulfurization apparatus of the present invention will be described below with reference to the drawings. In the embodiment shown in FIGS. 1 and 2, FIG. 1 shows a side surface of an absorption tower in which a liquid recovery section is provided on the wall of the absorption tower, and a pipe for introducing the liquid recovered by the liquid recovery section into a circulation tank is installed. is there. FIG. 2 is a sectional view taken along the line AA of FIG.

The embodiment shown in FIG. 1 has a prior art shown in FIG. 14 in that a liquid recovery section 18 is provided on the wall surface of the absorption tower and a liquid discharge pipe 19 for supplying the recovered liquid to the circulation tank 6 is provided. Different from The same members as those described in FIG. 14 are designated by the same reference numerals and the description thereof will be omitted.

Absorbing liquid 5 sprayed from the spray nozzle 13
Absorbs SO ₂ in the exhaust gas in the absorption tower to produce Ca (HS
O ₃ ) ₂ is produced and falls into the circulation tank 6. In the circulation tank 6, air 15 is supplied from an air blowing pipe 8, and Ca (HSO ₃ ) ₂ in the absorbing liquid that has fallen is oxidized by oxygen in bubbles atomized by the stirrer 7 to generate sulfuric acid. It becomes calcium. The bubbles existing in the circulation tank 6 include a foam layer 16 in addition to the bubbles of oxidizing air. The foam layer 16 is fine bubbles generated by entraining the gas in the absorption tower when the absorbing liquid 5 sprayed from the spray nozzle 13 drops onto the liquid surface in the circulation tank 6.
The fine bubbles forming the foam layer 16 do not contribute to the oxidation of sulfite ion (SO ₃ ²⁻ ) because the low oxygen concentration gas in the absorption tower is the main component. On the other hand, the fine air bubbles forming the foam layer 16 are sucked into the circulation pump 4 and the spray nozzle 1
The amount of circulating liquid of the absorbing liquid 5 for injection from 3 is reduced,
It also causes the liquid level in the circulation tank 6 to increase (hold up).

Regarding the suction of air bubbles into the circulation pump 4, a baffle plate 17 is installed near the suction port of the circulation pump 4 on the wall surface of the circulation tank to separate the liquid from the air bubbles and suck only the liquid into the circulation pump 4. ing.
On the other hand, regarding the hold-up, when the liquid level becomes higher than the wall surface of the absorption tower where the inlet duct 2 is installed, the liquid flows back into the inlet duct 2, so in order to prevent this, in the conventional technology, the liquid level is increased by the hold-up. The tank capacity considering the amount is used as the design value of the circulation tank 6.

However, the increase in the tank capacity of the circulation tank 6 increases the height of the absorption tower, which is an obstacle to downsizing of the desulfurization apparatus. In order to minimize the hold-up, the amount of bubbles in the foam layer 16 that does not contribute to the oxidation of sulfite ion (SO ₃ ²⁻ ) should be reduced. The foam layer 16 is generated by the liquid dropped onto the liquid surface in the circulation tank 6, but the liquid drops are the droplet-shaped absorption liquid 5 as it is jetted from the spray nozzle 13 that drops to the center of the circulation tank 6 and the tower wall. It is classified into two types of absorption liquid that is transmitted and flows into the circulation tank 6. While the droplet-shaped absorbing liquid is dispersed and dropped in the central portion of the tank, the absorbing liquid 5 flowing along the tower wall and flowing into the circulation tank 6 concentrates in a narrow region near the wall. Furthermore, the amount of the absorbing liquid that propagates through the tower wall reaches 20 to 30% of the amount of the liquid injected from the spray nozzle 13. 1/4 to 1 of the total circulating fluid amount near the wall of the circulating tank 6
Since a liquid amount of / 3 flows into a narrow area near the tank wall in a concentrated manner, a large amount of gas is entrained, which is the main cause of forming the foam layer 16.

In the embodiment shown in FIG. 1, the liquid falling along the tower wall of the absorption tower body 1 into the circulation tank 6 is once collected by the trough-shaped liquid collecting section 18, and the absorbing liquid flowing along the tower wall is collected. Is prevented from directly flowing into the liquid surface in the circulation tank 6.
The liquid recovery part 18 is inclined toward the liquid discharge pipe 19 to prevent the gypsum in the absorbing liquid from accumulating in the recovery part, and to collect the recovered liquid in the circulation tank 6 as shown in FIG. It is poured into the arranged liquid discharge pipe 19.

The outlet at the lower end of the liquid discharge pipe 19 is connected to the circulation tank 6
By extending below the liquid surface of the absorbent liquid, the absorbing liquid passes through the liquid discharge pipe 19 and quickly flows into the circulation tank 6, so that the gas in the absorption tower is not entrained and the foam layer 16 Occurrence is suppressed. The size of the liquid recovery unit 18 varies depending on the amount of the absorbing liquid discharged from the spray nozzle 13, the tower diameter, the gas flow rate, etc., but the width is 300 to 1000.
mm, height about 200-500 mm, liquid discharge pipe 1
The diameter of 9 is about 300 mm to 500 mm.

FIG. 3 is a comparison of the amount of bubbles in the foam layer 16 of the above-described embodiment of the present invention with that of the conventional technique as 1.

It can be seen that the formation of the foam layer 16 is suppressed by installing the liquid recovery section 18 according to the present invention. Therefore, the hold-up is reduced, the height of the circulation tank 6 can be set lower than in the prior art, and the absorption tower becomes more compact.

The embodiment shown in FIG. 4 is different from the embodiment shown in FIGS. 1 and 2 in that the outlet of the liquid discharge pipe 19 is oriented in the horizontal direction, and other configurations are the same as those shown in FIGS. It is the same. In the embodiment shown in FIGS. 1 and 2, the absorbing liquid collected along the wall surface of the absorption tower body 1 and collected in the liquid collecting section 18 is a liquid discharge pipe 19
Is discharged vertically from. At this time, a strong downward flow is generated near the outlet of the liquid discharge pipe 19. Depending on the liquid flow in the circulation tank 6, the flow of the absorbing liquid remains as it is in the suction pipe 1.
Since it is sucked into the circulation pump 4 from 4, the residence time of the liquid discharged from the liquid discharge pipe 19 is insufficient for the oxidation of sulfite ion (SO ₃ ²⁻ ). In order to prevent this, in FIG. 4, the outlet of the liquid discharge pipe is oriented in the horizontal direction to prevent the generation of the downward flow.

The essential part of another embodiment of the present invention is shown in FIG. 5. In this embodiment, the liquid recovery part 18 is tilted with respect to the horizontal direction and kept away from the circulation pump suction port connected to the suction pipe 14. The embodiment is different from the embodiment shown in FIGS. 1 to 4 in that the liquid discharge pipe 19 is provided at the lowest position of the liquid recovery unit 18 which is a different position. Other configurations are the same as those of the embodiment shown in FIGS.

The liquid recovered by the liquid recovery unit 18 contains some air bubbles having a small oxygen content. For this reason,
The outlet of the liquid discharge pipe 19 is not provided in the vicinity of the circulation pump suction pipe 14, and the liquid discharge pipe 19 is provided in the liquid recovery unit 18 on the opposite side of the portion where the suction pipe 14 of the circulation tank 6 is installed. Liquid recovery unit 18 into the absorption liquid in the circulation tank 6 from
By pouring the liquid inside, it is possible to reduce the proportion of the collected liquid containing bubbles with a low oxygen content mixed into the circulation pump 14.

In the embodiment shown in FIG. 6, the liquid flowing out from the liquid shield plate 20 provided on the upper part of the inlet duct 2 is poured into the tank together with the liquid recovered by the liquid recovery unit 18. ~ Different from the embodiment shown in FIG. Other configurations are the same as those of the embodiment shown in FIGS.

Of the absorbing liquid flowing down the tower wall of the absorption tower body 1, the liquid falling through the opening of the absorption tower body 1 in which the inlet duct 2 is installed shuts off the exhaust gas flow flowing into the absorption tower. High pressure loss in the flow.

In order to prevent this, in the embodiment shown in FIG.
The liquid shielding plate 20 is provided above the opening of the absorption tower main body 1 in which the inlet duct 2 is installed, and the liquid discharge pipes 21 are provided at both ends of the liquid shielding plate 20, and the opening of the absorption tower main body 1 in which the inlet duct 2 is installed. A liquid recovery unit 18 is provided below for recovering the liquid falling from the liquid discharge pipes 21 provided at both ends of the liquid shield plate 20 and at the same time collecting the absorbed liquid flowing down along the wall surface of the other absorption tower body 1. . Further, an appropriate number of liquid discharge pipes 19 are connected to the liquid recovery unit 18 as in the other embodiments.

In this way, the liquid absorbing plate 20 and the liquid recovery unit 18 absorb the droplet-shaped absorbing liquid as it is ejected from the spray nozzle 13.
Is collected and poured into the circulation tank 6, the foam layer 16
Is suppressed.

The embodiment shown in FIG. 7 shows a liquid storage part 18 provided between the liquid recovery part 18 and the liquid discharge pipe 19 in the embodiment shown in FIGS.
It differs from the embodiment shown in FIG. In the embodiment shown in FIGS. 1 to 6, the liquid recovered by the liquid recovery unit 18 flows into the opening of the liquid discharge pipe 19 as it is. At this time, the gas in the tower may be mixed with the liquid. When the liquid reservoir 22 is installed, the liquid recovered by the liquid recovery unit 18 temporarily accumulates in the liquid reservoir, so that the exhaust gas can be prevented from flowing into the liquid in the circulation tank 6 together with the liquid.

In the embodiment shown in FIG. 8, the liquid recovery section 18 is constituted by a flat plate having an opening vertically above and having an angle with respect to the tower wall, and has a bottom surface whose vertical section is an inverted triangle. It is different from the embodiment shown in FIGS. The liquid recovery unit 18 of this embodiment is an inclined liquid recovery unit 18 in which the wall surface side connected to the absorption liquid suction pipe 14 is the highest portion and the wall surface side connected to the inlet duct 2 is the lowest portion.

In this embodiment, since the liquid recovery section 18 is formed of a flat plate, the structure becomes simpler than that of the embodiment shown in FIGS. 1 to 7, and the cost is reduced.

In the embodiment shown in FIG. 9, the liquid recovery part 18 is divided into two parts in the inner peripheral surface direction of the side wall of the circulation tank 6, and both ends of the trough of the liquid recovery part 18 are one when viewed from the vertical direction of the tower wall surface. It is characterized in that they are arranged at positions overlapping in the upper and lower parts.

For example, in the embodiment shown in FIG. 5, since the liquid recovery part 18 is inclined toward the liquid discharge pipe 19,
The liquid recovery part 19 becomes higher in the vertical direction, and the height of the absorption tower body 1 or the circulation tank 6 becomes higher. However, in the embodiment shown in FIG. 9, the liquid recovery unit 18 is divided in the circumferential direction, and each liquid recovery unit 1
Since 8a and 18b are arranged so as to be inclined, the collected liquid drops into the circulation tank 6 from the liquid discharge pipes 19a and 19b connected to the lowest part thereof.

Moreover, since both ends of the tubs of the liquid recovery parts 18a and 18b partially overlap each other when viewed from the vertical direction of the tower wall surface, the liquid recovery part 18 can be made compact in the vertical direction.

Further, the number of divisions of the liquid recovery section 18 along the inner peripheral surface of the side wall of the circulation tank 6 may be an appropriate number of two or more.

The embodiment shown in FIG. 10 is an example in which the liquid recovery part 18 is inclined so that the lowest part of the liquid recovery part 18 is immersed in the absorbing liquid in the circulation tank 6, and no liquid discharge pipe is installed. Is.

By pouring the liquid collected by the liquid collecting section 18 along the slope as it is onto the liquid surface (shaded portion) of the circulation tank 6, the liquid discharge pipe 19 is omitted and the vertical height of the circulation tank 6 is reduced. Therefore, the liquid recovery unit 18 can be simplified and the circulation tank 6 can be made compact.

The embodiment shown in FIG. 11 is similar to the embodiment shown in FIG. 10 in that the lowermost part of the liquid recovery part 18 is soaked in the absorbing liquid in the circulation tank 6 or in the vicinity of the liquid surface. This is an example in which the recovery unit 18 is arranged obliquely and a liquid discharge pipe is not installed. The embodiment shown in FIG. 11 differs from the embodiment shown in FIG. 10 in that the liquid recovery part 18 is divided into two (or two or more) in the inner peripheral direction of the side wall of the circulation tank 6. The vertical height of 6 can be reduced, the liquid recovery part 18 can be simplified, and the circulation tank 6 can be made compact.

The embodiment shown in FIG. 12 is different from the embodiments shown in FIGS. 1 to 10 in that the liquid recovery section 18 is a flat plate perpendicular to the tower wall and there is no liquid discharge pipe. 12
In the embodiment shown in (1), the liquid recovery unit 18 is a flat plate perpendicular to the wall surface, and the liquid flowing down along the tower wall once collides with the liquid recovery unit 18 to reduce the falling speed, and then the flat plate Fall from the edge. At this time, since the speed of the liquid falling on the liquid surface in the circulation tank 6 is slower than that in the case where the liquid recovery unit 18 is not provided, the amount of gas in the tower that is entrained in the liquid also decreases, and the foam layer 16 generated decreases. . Although its effect is inferior to that of the other embodiments, it is effective when it is desired to simplify the structure of the liquid recovery unit 18 and thus reduce the installation cost of the liquid recovery unit 18.

The embodiment shown in FIG. 13 is different from the embodiment shown in FIGS. 1 to 6 in that the present invention is applied to a desulfurization apparatus in which the diameter of the circulation tank 6 is larger than the diameter of the absorption tower body 1. When the diameter of the circulation tank 6 is larger than the diameter of the absorption tower body 1,
As shown in FIG. 13, a step is formed between the absorber of the absorber main body 1 and the side wall of the circulation tank 6. The absorbing liquid flowing down along the tower wall of the absorbing section once separates from the wall surface and falls into the circulation tank 6 due to this step. At this time, since a large amount of gas is entrained, the amount of bubbles in the foam layer 16 is larger than in an absorption tower having no steps that flow along the wall surface and flow into the circulation tank 6.

Therefore, the liquid recovery unit 18 with the liquid discharge pipe 19
The formation of the foam layer 16 can suppress the generation of the foam layer 16, and its effect is greater than that of the embodiment shown in FIGS.

[0052]

As described above, according to the present invention, it is possible to suppress the formation of a foam layer on the absorbing liquid surface in the circulation tank. Since the amount of fine bubbles in the foam layer decreases and the hold-up amount decreases, the volume of the circulation tank can be small and the desulfurization device can be made compact. Furthermore, since the suction of the foam layer into the circulation pump is reduced, it is possible to prevent a decrease in the amount of circulating liquid and a reduction in the desulfurization rate, and to provide a highly reliable and high-performance wet flue gas desulfurization device.

[Brief description of drawings]

FIG. 1 is a side view of an absorption tower in which a liquid recovery unit is provided on a wall of an absorption tower according to an embodiment of the present invention, and a liquid discharge pipe for introducing a liquid recovered by the recovery unit into a circulation tank is installed.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a diagram comparing the amount of bubbles in a foam layer according to the related art with that of the related art, with the related art as 1.

FIG. 4 is a side view of the absorption tower showing a liquid recovery unit in which the liquid discharge pipe outlet of the embodiment of the present invention is oriented in the horizontal direction.

FIG. 5 is a schematic view of an absorption tower showing a liquid recovery section provided with a discharge pipe for injecting the recovered liquid on the side opposite to the suction port of the circulation pump according to the embodiment of the present invention.

FIG. 6 is a schematic view of an absorption tower in which a liquid shielding plate provided on an upper portion of an inlet duct of the embodiment of the present invention is installed.

FIG. 7 is a schematic diagram of an absorption tower in which a liquid reservoir is provided between a liquid recovery unit and a liquid discharge pipe according to an embodiment of the present invention.

FIG. 8 is a schematic view of an absorption tower in which the liquid recovery section of the embodiment of the present invention is a flat plate having an opening vertically upward and having an angle with respect to the tower wall.

FIG. 9 is a schematic view of an absorption tower when the liquid recovery unit of the embodiment of the present invention is divided in the inner peripheral surface direction of the side wall of the circulation tank.

FIG. 10 is a schematic view of an absorption tower in which the liquid discharge pipe of the embodiment of the present invention is omitted.

FIG. 11 is a schematic view of an absorption tower in which the liquid discharge pipe of the embodiment of the present invention is omitted.

FIG. 12 is a side view of an absorption tower in which the liquid recovery part of the embodiment of the present invention is a flat plate perpendicular to the tower wall.

FIG. 13 is a side view of a desulfurization device in which the diameter of the circulation tank is larger than the diameter of the absorption tower of the embodiment of the present invention.

FIG. 14 is a side view of a prior art desulfurizer.

[Explanation of symbols]

1 Absorption tower main body 2 Entrance duct 3 Outlet duct 4 Absorbing liquid circulation pump 5 absorption liquid 6 circulation tank 7 Stirrer 8 Air supply pipe 9 Mist eliminator 10 Absorption liquid extraction pipe 11 Circulation piping 12 Spray header 13 Spray nozzle 14 Suction pipe 15 Oxidized air bubbles 16 Foam layer 17 Baffle plate 18 Liquid recovery part 19 Liquid discharge pipe 20 Liquid shield plate 21 liquid discharge pipe 22 liquid reservoir

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirofumi Yoshikawa             Babcock Hitachi 3-36 Takaracho, Kure City, Hiroshima Prefecture             Kure Institute Co., Ltd. (72) Inventor Naoki Oda             Babcock Hitachi 6-9 Takaracho, Kure City, Hiroshima Prefecture             Kure Office Co., Ltd. F-term (reference) 4D002 AA02 AC01 BA02 BA16 CA01                       CA20 DA05 DA16 EA02 EA12                       FA03

Claims (12)

[Claims] 1. An absorption part provided with an inlet duct for introducing a sulfur oxide-containing exhaust gas discharged from a combustion device such as a boiler, and a gas-liquid contact region for contacting the exhaust gas introduced from the inlet duct with a calcium-based absorption liquid. And an absorption tower having an outlet duct for discharging the exhaust gas purified by the absorption section, a circulation tank for storing an absorption liquid used for purification processing of the exhaust gas in the absorption tower under the absorption tower, and the circulation In a wet flue gas desulfurization device equipped with an absorbing liquid circulation system that circulates a portion of the absorbing liquid in the tank to the gas-liquid contact region of the absorption tower, the liquid that falls along the wall of the absorbing tower into the circulation tank A wet flue gas desulfurization apparatus, characterized in that a trough-shaped liquid recovery unit is provided on a wall surface of the circulation tank to collect and then pour the collected liquid into a circulation tank so as to reduce a fall distance to the liquid level of the circulation tank. 2. The liquid recovery part is provided with a liquid recovery gutter having an inclined surface with respect to the horizontal, which is installed over a part or the whole of the inner surface of the side wall of the circulation tank in the inner circumferential direction. Wet flue gas desulfurization equipment. 3. The liquid recovery part is characterized in that a liquid discharge pipe having a lower end outlet immersed in the liquid of the circulation tank is connected to the lowest part of the inclined surface of the liquid recovery gutter. Wet flue gas desulfurization equipment. 4. The wet flue gas desulfurization apparatus according to claim 3, wherein the outlet of the lower end of the liquid discharge pipe is oriented horizontally. 5. A liquid recovery section is provided with a trough for liquid recovery on the inner wall surface of the absorption tower above the inlet duct, and a liquid discharge pipe for discharging the recovered liquid from the trough to a liquid recovery trough provided on the wall surface of the circulation tank. The wet flue gas desulfurization apparatus according to claim 1, which is connected. 6. The lower end outlet of the liquid discharge pipe is provided at a position distant from the circulation tank connection part of the absorption liquid circulation system for supplying a part of the absorption liquid in the circulation tank to the gas-liquid contact region of the absorption tower. The wet flue gas desulfurization device according to claim 1. 7. The wet flue gas desulfurization apparatus according to claim 3, wherein a temporary storage part for the recovered liquid is provided at a connection part of the liquid discharge pipe with the liquid recovery gutter. 8. The wet process according to claim 1, wherein the liquid collecting trough has a structure including a side wall surface and a bottom surface of the circulation tank and a balustrade, or a structure in which the circulation tank wall surface and a flat plate are connected in an inverted triangular cross section. Flue gas desulfurization equipment. 9. The liquid collecting gutter is divided into two or more parts for the entire circumference of the wall surface of the circulation tank, and both end parts of each divided gutter overlap vertically with the other end parts of other gutters. The wet flue gas desulfurization apparatus according to claim 1, wherein the wet flue gas desulfurization apparatus is disposed at a predetermined position. 10. The wet flue gas desulfurization apparatus according to claim 9, wherein a liquid discharge pipe is connected to the lowest part of each of the divided gutters. 11. The wet flue gas desulfurization apparatus according to claim 1, wherein the liquid recovery gutter has the lowest part of the inclined surface of the liquid recovery gutter immersed in the liquid in the circulation tank. 12. The wet flue gas desulfurization apparatus according to claim 1, wherein the liquid recovery gutter comprises a flat plate which is erected in a direction substantially vertical to a side wall surface of the circulation tank.