JPH10328529A - Flue gas desulfurization equipment - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide a flue gas desulfurization apparatus capable of removing air bubbles from an absorbing liquid extracted from a liquid reservoir of an absorption tower. SOLUTION: In a flue gas desulfurization apparatus 20 in which a pump 2 for spraying and circulating an alkali absorbent is connected to an absorption tower 1, the pump 2 is provided at a lower portion outside the absorption tower 1 and an outlet pipe of the pump 2 is provided. 3b is erected above the liquid reservoir 1a of the absorption tower 1, and the erected outlet pipe 3b and the absorption tower 1
Recycling pipe 8 that connects to the liquid reservoir 1a and returns the slurry
And connects the recycling pipe 8 to the inlet pipe 3a of the pump 2 to connect an air bubble removal pipe 9 for collecting bubbles contained in the slurry from the upper surface of the inlet pipe 3a to the recycling pipe 8. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flue gas desulfurization apparatus for spraying a slurry containing an alkali absorbent in an absorption tower, contacting the exhaust gas, and desulfurizing the exhaust gas. The present invention relates to a flue gas desulfurization apparatus capable of removing bubbles from a slurry sucked by a pump by improving a slurry circulation means for extracting the recovered slurry by a pump and returning the slurry to an upper portion of an absorption tower.

[0002]

2. Description of the Related Art Exhaust gas (smoke exhaust) generated when burning fuel such as coal contains a relatively large amount of sulfur, and it is necessary to desulfurize the exhaust gas with a flue gas desulfurization device.

FIG. 4 is a schematic view of a general flue gas treatment system. As a part of the conventional flue gas treatment system, a slurry liquid (hereinafter, referred to as a slurry) containing an alkali absorbent is sprayed on exhaust gas to desulfurize the exhaust gas. Is shown.

[0004] As shown in the figure, the flue gas treatment system includes a boiler 10, a denitration device 11, an air heater (A / H) 12, an electric dust collector (EP) 13, and a gas gas heater (GGH) 14 which are connected in order. , Flue gas desulfurization equipment 30, chimney 15
Mainly composed of

[0005] The flue gas desulfurization unit 30 comprises an absorption tower 1, a slurry circulation means 3 connected to the absorption tower 1 via a pump 2,
A spray nozzle 4 provided at the top of the absorption tower 1 connected to the slurry circulation means 3; and an oxidizing means 5 provided at the bottom of the absorption tower 1 (for forcibly oxidizing a sulfite or the like generated as a result of the desulfurization reaction). And a mist eliminator 6 provided near the outlet of the absorption tower 1 and a slurry supply means 7 for supplying a slurry to the absorption tower 1.

[0006] The absorption tower 1 is configured such that exhaust gas is introduced from a lower part thereof and discharged from an upper part thereof. At the bottom of the absorption tower 1, there is formed a liquid reservoir 1a in which slurry is stored. Further, a gypsum collecting means (not shown) is connected to the slurry circulating means 3.

[0007] Fuel such as coal is burned in the boiler 10 to generate exhaust gas containing sulfur. Exhaust gas containing sulfur is introduced from the boiler 10 to the denitration device 11 for denitration, and the denitrated exhaust gas is introduced into the lower part of the absorption tower 1 via the air heater 12, the electric dust collector 13 and the gas gas heater 14. You.

The exhaust gas introduced into the lower part of the absorption tower 1 rises in the absorption tower 1. At this time, a liquid (slurry) containing an alkali absorbent is sprayed on the exhaust gas through the spray nozzle 4, and as a result, the slurry and the exhaust gas come into gas-liquid contact, and the sulfur content contained in the exhaust gas is absorbed by the alkali absorbent. , Desulfurization is performed.

The desulfurized exhaust gas is discharged from the top of the absorption tower 1 via the mist eliminator 6 and discharged to the atmosphere via the gas gas heater 14 and the chimney 15.

On the other hand, the liquid stored in the liquid storage section 1a of the absorption tower 1 is pumped out by the pump 2 and returned to the spray nozzle 4 by the slurry circulating means 3 to be sprayed again. Thereafter, the above steps are repeated. . Slurry is appropriately supplied into the absorption tower 1 by the slurry supply means 7, and oxidizing air is fed into the liquid reservoir 1a of the absorption tower 1 by the oxidization means 5, and the sulfite (CaSO ₃ Etc.) are forcibly oxidized.

[0011]

In the above-mentioned conventional flue gas desulfurization apparatus, a large amount of oxidizing air is blown by the oxidizing means into the liquid stored in the liquid reservoir of the absorption tower.
Many bubbles are necessarily generated in the liquid. Therefore, when the liquid accumulated in the liquid reservoir of the absorption tower is sucked by the pump to be introduced into the slurry circulation means, bubbles are introduced into the pump together with the slurry, which not only affects the operation of the pump, but also affects the operation of the pump. In some cases, there has been a problem that the performance of the pump is reduced.

Accordingly, an object of the present invention is to provide a flue gas desulfurization apparatus capable of removing air bubbles from an absorbing liquid extracted from a liquid reservoir of an absorption tower.

[0013]

In order to achieve the above object, the present invention is directed to a flue gas desulfurization apparatus in which a pump for spraying and circulating an alkali absorbent is connected to an absorption tower. A recycling pipe that is provided at the lower part of the outside of the tower and raises the outlet pipe of the pump above the liquid storage part of the absorption tower, connects the raised outlet pipe to the liquid storage part of the absorption tower, and returns the slurry. The recycling pipe and the inlet pipe of the pump are connected to each other, and a bubble removal pipe for collecting bubbles contained in the slurry from the upper face of the inlet pipe to the recycling pipe is connected.

[0014]

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

FIG. 1 shows a part of a general flue gas treatment system, in which a slurry liquid (hereinafter, referred to as a slurry) containing an alkali absorbent is sprayed on exhaust gas to desulfurize the exhaust gas. Shown is a flue gas desulfurization device 20 of the present invention that can prevent the intrusion of bubbles into the pump when it is withdrawn.

As shown in the figure, this smoke exhaust treatment system includes a boiler 10, a denitration device 11, an air heater (A / H) 12, an electric dust collector (EP) 13, and a gas gas heater (GGH) 14, which are connected in this order. , Flue gas desulfurization equipment 20, chimney 15
Mainly composed of

The flue gas desulfurization apparatus 20 includes an absorption tower 1, a slurry circulation means 3 connected to the absorption tower 1 via a pump 2,
Spray nozzle 4 provided on top of absorption tower 1 connected to slurry circulation means 3 and oxidation means 5 provided on the bottom of absorption tower 1 (for forcibly oxidizing sulfites and the like generated as a result of desulfurization reaction) And a mist eliminator 6 provided near the outlet of the absorption tower 1 and a slurry supply means 7 for supplying a slurry to the absorption tower 1.

The absorption tower 1 is configured such that exhaust gas is introduced from a lower part thereof and discharged from an upper part thereof. At the bottom of the absorption tower 1, there is formed a liquid reservoir 1a in which slurry is stored. In FIG. 1, the absorption tower 1 is shown in a state where a slurry liquid is sufficiently stored in a liquid storage portion 1a. A gypsum collecting means (not shown) is connected to the slurry circulating means 3.

FIG. 2 is an enlarged view of the liquid reservoir 1a, the pump 2 and the slurry circulation means 3 near the pump 2 of the absorption tower 1 shown in FIG.

As shown in FIG. 2, the slurry circulating means 3 of the present invention includes an inlet-side pipe 3a upstream (inlet side) of the pump 2 and a downstream side (outlet side) of the pump 2. ) And the outlet side pipe 3b. Generally, the inlet side pipe 3a of the slurry circulation means 3 is connected to the liquid reservoir 1a of the absorption tower 1.
The slurry discharge port 16 and the pump 2 are connected to each other so as to be substantially horizontal by connecting the pump 2 and the slurry circulation means 3.
The outlet side pipe 3b rises perpendicularly to the inlet side pipe 3a from the pump 2 and extends along the side of the absorption tower 1.

As shown in FIG. 2, the slurry circulation means 3
From the outlet side pipe 3b, at an appropriate position on the pump 2 (for example, a point where the pump 2 rises by about 2 m), a recycle pipe 8 for returning a part of the slurry from the outlet side pipe 3b to the absorption tower 1 is connected to the outlet side. The side of the pipe 3b on the side of the absorption tower 1 and the side of the absorption tower 1 are connected in a substantially horizontal direction.

From the inlet side pipe 3a of the slurry circulating means 3, a bubble removing pipe 9 which captures bubbles in the slurry and flows a part of the slurry from the inlet side pipe 3a to the recycle pipe 8 is connected to the inlet side pipe 3a. 2 and the lower part of the recycle pipe 8 is connected almost vertically to the upper part of FIG.
(And FIG. 3A).

The position of the air bubble removal pipe 9 is determined by a strainer section (shown in the figure) provided below the inlet side pipe 3a in order to effectively separate bubbles from the inlet side pipe 3a of the slurry circulation means 3. However, it may be provided at a location where the flow velocity of the slurry is partially reduced, such as immediately above the location.

Similarly, in order to effectively separate bubbles from the inlet pipe 3a of the slurry circulating means 3, at the connection between the bubble removing pipe 9 and the upper surface of the inlet pipe 3a, the inlet pipe of this portion is connected. The upper surface 3a has a shape that easily collects bubbles (for example, a flat box-shaped portion 3c shown in FIG. 3B).
May be formed.

Further, regarding the specific ratio of the diameter of the recycle pipe 8 to the bubble removal pipe 9 and other specific configurations, the flow rate of the slurry flowing in the recycle pipe 8 is determined by the air bubbles in the bubble removal pipe 9 connected to the recycle pipe 8. In addition, the flow velocity is sufficiently higher than the flow velocity of some of the slurries (flowing together with the bubbles). Therefore, an ejector effect is generated in these pipes 8 and 9 due to the flow velocity difference, and the slurry exiting the bubble removal pipe 9 is quickly moved to the absorption tower 1 side. It is desirable to be configured to be sucked in.

The recycle pipe 8 and the bubble removal pipe 9
In both cases, the diameter of the pipe is set to about 15A to 25A so that the circulation flow rate of the slurry circulation means 3 is not affected.

Fuel such as coal is burned in the boiler 10 to generate sulfur-containing exhaust gas. Exhaust gas containing sulfur is introduced from the boiler 10 to the denitration device 11 for denitration, and the denitrated exhaust gas is introduced into the lower part of the absorption tower 1 via the air heater 12, the electric dust collector 13 and the gas gas heater 14. You.

The exhaust gas introduced into the lower part of the absorption tower 1 rises in the absorption tower 1. At this time, a liquid (slurry) containing an alkali absorbent is sprayed on the exhaust gas through the spray nozzle 4, and as a result, the slurry and the exhaust gas come into gas-liquid contact, and the sulfur content contained in the exhaust gas is absorbed by the alkali absorbent. , Desulfurization is performed.

The desulfurized exhaust gas is discharged from the top of the absorption tower 1 through the mist eliminator 6 and discharged to the atmosphere through the gas gas heater 14 and the chimney 15.

On the other hand, the liquid collected in the liquid storage section 1 a of the absorption tower 1 is pumped by the pump 2 through the slurry circulation means 3.
And is returned to the spray nozzle 4 and sprayed again, and the above process is repeated thereafter. Slurry is appropriately supplied into the absorption tower 1 by the slurry supply means 7, and oxidizing air is fed into the liquid reservoir 1a of the absorption tower 1 by the oxidization means 5, and the sulfite (CaSO ₃ Etc.) are forcibly oxidized.

As described above, air is blown into the (slurry) liquid stored in the liquid storage section 1a of the absorption tower 1 by the oxidizing means 5 as described above, and as a result, fine bubbles are generated in the slurry. Therefore, when the slurry is withdrawn from the liquid reservoir 1a of the absorption tower 1 by the pump 2 and introduced into the inlet-side pipe 3a of the slurry circulating means 3, these minute bubbles are also sucked together with the slurry and are sent to the inlet-side pipe 3a. enter.

However, due to its specific gravity, the bubbles flow along the upper part of the pipe of the inlet side pipe 3a of the slurry circulating means 3 together with part of the slurry. It rises in the bubble removal pipe 9 together with a part of the slurry. On the other hand, the remaining slurry from which bubbles have been removed by the bubble removing pipe 9 enters the outlet side pipe 3b of the slurry circulating means 3 via the pump 2, and a part of the slurry branches off to the recycling pipe 8 and via the recycling pipe 8. The remainder is returned to the absorption tower 1, and the remainder goes up the outlet side pipe 3 b of the slurry circulation means 3 and is guided to the spray nozzle 4.

The bubbles and the slurry branched to the bubble removing pipe 9 rise in the bubble removing pipe 9 and enter the recycling pipe 8. Then, since the ejector effect is generated in the pipes 8 and 9 as described above, the bubbles and the slurry that have flowed out of the bubble removing pipe 9 are quickly sucked toward the absorption tower 1 by the ejector effect.

That is, the bubbles separated by the bubble removal pipe 9 are returned to the absorption tower 1 through the recycling pipe 8 without being lost, and the bubbles thus returned are collected in the liquid storage of the absorption tower 1. Even if they are extracted again from the section 1a, they are surely captured again by the bubble removal pipe 9 and returned into the absorption tower 1. Therefore, the amount of bubbles flowing into the pump 2 together with the slurry is greatly reduced, and as a result, the pump 2
Can always be maintained at an amount that does not affect the operation of the pump 2.

[0035]

In summary, according to the flue gas desulfurization apparatus of the present invention, the slurry is extracted from the absorption tower by improving the piping of the slurry circulating means for extracting and circulating the slurry from the absorption tower. Since the bubbles contained in the slurry can be reliably separated and returned to the absorption tower in a relatively simple manner, the amount of bubbles flowing into the pump can be significantly reduced, and therefore, the undesirable effects of the bubbles on the operation of the pump. Can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a schematic view of a general flue gas treatment system including a flue gas desulfurization device of the present invention.

FIG. 2 is a partially enlarged view of the flue gas desulfurization device of FIG.

FIG. 3A is an enlarged side sectional view of a connection portion between an inlet-side pipe and a bubble removing pipe in FIG. 2;

FIG. 3B is another enlarged sectional side view of a connection portion between the inlet-side pipe and the bubble removing pipe in FIG. 2;

FIG. 4 is a schematic view of a general flue gas treatment system including a conventional flue gas desulfurization device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Absorption tower 1a Liquid storage part 2 Pump 3a Inlet side piping 3b Outlet side piping 8 Recycle piping 9 Air bubble removal piping 20 Smoke flue gas desulfurization equipment

Claims (1)

[Claims] In a flue gas desulfurization apparatus in which a pump for spraying and circulating an alkali absorbent is connected to an absorption tower, a pump is provided at a lower portion outside the absorption tower and an outlet pipe of the pump is connected to the absorption tower. A recycle pipe for returning the slurry by connecting the outlet pipe that has been raised up to the upper part of the liquid reservoir and the liquid reservoir of the absorption tower is connected, and connecting the recycle pipe to the inlet pipe of the pump. A flue gas desulfurization apparatus, wherein a bubble removal pipe for collecting bubbles contained in the slurry from the upper surface of the inlet side pipe to the recycling pipe is connected.