JPH11156154A - Flue gas desulfurization apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent stopping of a feed opening of a slurry feed pipe, and sedimentation and deposition of a solid content in the slurry feed pipe. SOLUTION: An absorbent slurry is fed from a plurality of feed openings 6a of a slurry feed pipe 6 to a liquid storage part 1a of an absorption tower 3 wherein the liquid storage part 1a of the absorption liquid 1 is formed in its lower part and many spray nozzles 2 are arranged in its upper part. Further, industrial water in a make-up water tank 7 is fed to the liquid storage part 1a through a feed water mother pipe 8. A feed water branch 15 is branched from midway to the feed water mother pipe 8, and its tip is connected to a slurry feed pipe to a downstream of a flow rate adjusting valve 14. Thereby, the absorbent slurry in the slurry feed pipe 6 is diluted with the industrial water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coal-fired boiler,
The present invention relates to a wet type flue gas desulfurization device for removing sulfur oxides contained in exhaust gas (gas to be treated) from other combustion equipment,
In particular, the present invention relates to technology for preventing solidification and accumulation of absorbent slurry.

[0002]

2. Description of the Related Art In a wet type flue gas desulfurization apparatus, an absorbent is pumped up from a liquid reservoir at the bottom and sprayed from above, and in the process of dropping the absorbent, the absorbent is brought into contact with exhaust gas to form a sulfur oxide. The liquid is returned to the liquid reservoir while absorbing the water, and oxidized by blowing air for oxidation while stirring the liquid in the liquid reservoir with stirring blades.

As shown in FIG. 4, this type of flue gas desulfurization apparatus has an absorption tower 3 in which a liquid reservoir 1a for absorbing liquid 1 is formed in a lower part and a number of spray nozzles 2 are arranged in an upper part. A circulating pump 4 for pumping up the absorbent 1 in the liquid reservoir 1 a of the absorption tower 3 and circulating it so as to spray it from the spray nozzle 2.
And an oxidizing air blower 5 for supplying oxidizing air to the liquid reservoir 1a of the absorption tower 3.

In the example shown in FIG.
The exhaust gas A, which is being circulated while being sprayed from the spray nozzle 2 by the operation of the exhaust gas A and sent into the absorption tower 3 through the exhaust gas introduction pipe 10 from a coal-fired boiler or the like (not shown) The contact with the upper exhaust pipe 11 after the sulfur oxides are absorbed and removed.
Is discharged to the outside via the.

On the other hand, a part of the absorbing liquid 1 having absorbed the sulfur oxides from the exhaust gas A is recovered as gypsum slurry from the bottom of the liquid reservoir 1a of the absorption tower 3, and water is removed from the gypsum slurry to remove gypsum. Is to be generated.

[0006] Further, in the liquid reservoir 1a of the absorption tower 3, a slurry supply pipe 6 having a supply port 6a opened near the liquid surface of the absorbent 1 in the liquid reservoir 1a is supplied with an absorbent slurry by a flow control valve. 14
Thus, the flow rate is appropriately controlled and supplied.

Further, a water supply mother pipe 8 for supplying make-up water from a make-up water tank 7 is connected to the liquid storage section 1a of the absorption tower 3, and a bottom of the liquid storage section 1a is connected to the absorption liquid 1a. A stirring blade 9 for stirring the water is provided.

The silo 12 in which the absorbent (lime, calcium carbonate, etc.) is stored upstream of the slurry supply pipe 6 (upstream in the flow direction of the absorbent slurry).
And an absorbent slurry pit 13 for kneading the absorbent supplied from the silo 12 and the absorbent supplied from a mother liquor tank (not shown) to produce an absorbent slurry.

[0009]

However, in such a conventional flue gas desulfurization apparatus, since the absorbent slurry has a high concentration, the absorbent slurry comes into contact with the exhaust gas A at the supply port 6a of the slurry supply pipe 6. In this case, solidification (scaling) due to heating is likely to occur, and the supply port 6a may be closed.

In addition, since the absorbent slurry having a high concentration of about 20% to 30% is used for reasons such as reducing the capacity of the transport pump, the solid content (absorbent) in the slurry supply pipe 6 is reduced. ) Tend to settle and deposit. When the solid content in the pipe increases, the absorbent slurry does not flow smoothly, and there is a possibility that a predetermined amount of the absorbent slurry cannot be supplied to the absorption tower 3.
Deposition was likely to occur when the input flow rate of the absorbent slurry was reduced due to a decrease in boiler load or the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a flue gas desulfurization apparatus capable of preventing a supply port of a slurry supply pipe from being clogged, and preventing sedimentation and accumulation of solids in the slurry supply pipe. It is intended for.

[0012]

According to the present invention, an absorbing solution is pumped up from a liquid reservoir formed at the bottom of an absorbing tower, and the absorbing solution is sprayed from a spray nozzle provided at an upper portion of the absorbing tower. In the flue gas desulfurization device that makes the exhaust gas and the absorbing liquid that are sent into the absorption tower come into contact with the absorption tower in the falling process to absorb the sulfur oxides in the exhaust gas, the slurry supply pipe that supplies the absorbent slurry to the liquid reservoir is And a diluting liquid mixing means for mixing the diluting liquid into the absorbent slurry on the downstream side of the liquid amount adjusting valve.

With this configuration, the diluting liquid is injected into the slurry supply pipe on the downstream side of the liquid amount adjusting valve, and the diluting liquid and the absorbent slurry are mixed, so that the concentration of the absorbent slurry is reduced. .

In the present invention, the diluting liquid mixing means is branched from a water supply main pipe for replenishing water to the liquid reservoir in order to maintain a constant level of the absorbing liquid in the liquid reservoir, and a tip end thereof. Is preferably constituted by a water supply branch pipe connected to the slurry supply pipe, and in this case, the industrial water is injected into the slurry supply pipe on the downstream side of the liquid amount adjusting valve to dilute the absorbent slurry. Becomes possible.

The supply port at the tip of the slurry supply pipe is
It is preferable to be branched into a plurality of portions via the header and open at appropriate portions of the absorption tower, so that the absorbent slurry can be uniformly supplied over a wide range of the liquid reservoir of the absorption tower. Becomes possible.

[0016]

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

FIGS. 1 and 2 show an embodiment of the present invention. In this embodiment, the basic structure is almost the same as that of the conventional example shown in FIG. At the downstream side of the flow control valve 14 provided in the middle of the pipe 6, the tip of a water supply branch pipe 15 branched from the middle of the water supply mother pipe 8 so as to mix the diluting liquid with the absorbent slurry in the slurry supply pipe 6. Is connected to the slurry supply pipe 6 on the downstream side of the flow control valve 14 to constitute a diluting liquid mixing means.

The industrial water in the makeup water tank 7 is
The water is supplied to the liquid reservoir 1a of the absorption tower 3 as needed by the water supply mother pipe 8, and is also injected into the inside of the slurry supply pipe 6 through the water supply branch pipe 15 through the flow control valve 16.

Mixing industrial water with the absorbent slurry
The high concentration (about 20% to 30%) absorbent slurry is diluted to prevent blockage due to scaling at the supply port 6a of the slurry supply pipe 6, and to prevent sedimentation and accumulation of solids in the slurry supply pipe 6. To do that. Therefore, the diluting liquid does not have to be industrial water, and for example, a low-concentration slurry such as a filtrate of a gypsum recovery system may be used.

The supply flow rate of the industrial water is controlled by the flow control valve 16 of the water supply branch pipe 15 in accordance with the increase or decrease of the supply amount of the absorbent slurry so that the flow rate of the diluted absorbent slurry is always constant. Good to do.

In such a configuration, a part of the absorbing liquid 1 is pumped up from the liquid reservoir 1a by the circulation pump 4 and sprayed from the spray nozzles 2 of each stage. In this state, the exhaust gas A to be desulfurized is introduced into the exhaust gas. When the exhaust gas A is introduced into the absorption tower 3 from the pipe 10, the exhaust gas A comes into contact with the absorption liquid 1 sprayed from the spray nozzles 2 of each stage while ascending the inside of the absorption tower 3 to remove sulfur oxides. 1 and is discharged from the exhaust pipe 11.

On the other hand, the absorbent 1 having absorbed sulfur oxides from the exhaust gas A is dropped into the liquid reservoir 1a.
When the oxidizing air is blown by the oxidizing air blower 5 and stirred by the rotation of the stirring blades 9, the absorbing solution 1 having absorbed the sulfur oxides absorbs the sulfur oxides from the exhaust gas A, and thus is absorbed in the absorbing solution 1. The generated calcium sulfite is oxidized to generate stable gypsum (calcium sulfate). This gypsum is collected from a gypsum outlet (not shown).

In such a series of flue gas desulfurization processes,
As the water in the liquid reservoir 1a evaporates and goes out of the absorption tower 3,
Since the water level of the absorbing liquid 1 in the liquid reservoir 1a drops, industrial water is supplied to the liquid reservoir 1a from the makeup water tank 7 through the water supply mother pipe 8 as appropriate. By replenishing this industrial water,
The level of the absorbing liquid 1 in the liquid reservoir 1a is kept constant.

Further, as described above, the absorbent slurry has a high concentration, and as the load on the combustion equipment decreases and the flow rate of the absorbent slurry decreases, the solids settle in the slurry supply pipe 6,
Easy to deposit. Further, the absorbent slurry may be solidified at the supply port 6a of the slurry supply pipe 6 due to the high heat of the exhaust gas A, and may block the supply port 6a.

Therefore, if the industrial water in the makeup water tank 7 is injected into the slurry supply pipe 6 through the water supply branch pipe 15, the absorbent slurry is diluted, and the above-mentioned problem does not occur.

In this embodiment, as shown in FIG. 2, the supply port 6a of the slurry supply pipe 6 is divided into a plurality of parts via a header 6b so as to be opened at a plurality of appropriate locations in the absorption tower 3. This makes it possible to supply the absorbent slurry uniformly over a wide range of the liquid reservoir 1a of the absorption tower 3.

In the example shown in FIG. 2, the rectangular absorption tower 3
(Thus, the liquid reservoir 1a is also square.)
As shown in FIG. 3, the cylindrical absorption tower 3 (accordingly, the liquid reservoir 1a)
A similar configuration can also be adopted in the case of a cylindrical type. In particular, in the drawing, the header 6b is formed in an arc shape,
A plurality of supply ports 6a are opened at an equal angle on the outer periphery of the absorption tower 3.

Thus, the supply port 6a of the slurry supply pipe 6
Is divided into a plurality through the header 6b, and the absorbent slurry is uniformly supplied over a wide range of the liquid reservoir 1a, whereby the stirring efficiency of the absorbing liquid 1 by the stirring blade 9 can be increased.

Incidentally, the flue gas desulfurization apparatus of the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the scope of the present invention.

[0030]

According to the above-mentioned flue gas desulfurization apparatus of the present invention, the following various excellent effects can be obtained.

(I) According to the first aspect of the present invention, the diluting liquid is mixed with the absorbent slurry on the downstream side of the liquid amount adjusting valve in the slurry supply pipe, so that the absorbent slurry is diluted. Blockage of the supply port of the slurry supply pipe, and sedimentation and accumulation of solids in the slurry supply pipe can be prevented.

(II) According to the second aspect of the present invention, the absorbent slurry can be diluted with a simple structure that only branches industrial water for adjusting the level of the absorbent in the liquid reservoir.

(III) According to the third aspect of the present invention,
Since the supply port of the slurry supply pipe is divided into a plurality of parts via the header, the absorbent slurry can be supplied uniformly over a wide range of the liquid reservoir of the absorption tower, and the stirring efficiency of the absorbent can be increased. it can.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an example of an embodiment for implementing the present invention.

FIG. 2 is a plan view showing an example of arrangement of supply ports of a slurry supply pipe in the absorption tower of FIG.

FIG. 3 is a plan view showing an example of arrangement of supply ports of a slurry supply pipe adopted in a cylindrical absorption tower.

FIG. 4 is an overall configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Absorbent liquid 1a Liquid storage part 2 Spray nozzle 3 Absorption tower 6 Slurry supply pipe 6a Supply port 6b Header 8 Water supply main pipe 14 Flow control valve 15 Water supply branch pipe (diluting liquid mixing means) A Exhaust gas

Claims (3)

[Claims] An absorption liquid is pumped up from a liquid reservoir formed at the bottom of an absorption tower, and the absorption liquid is sprayed from a spray nozzle disposed at an upper part of the absorption tower. In the flue gas desulfurization device that makes the exhaust gas and the absorption liquid come into contact with each other and absorbs the sulfur oxides in the exhaust gas, the slurry supply pipe that supplies the absorbent slurry to the liquid reservoir portion has a liquid amount adjustment valve downstream side. A flue gas desulfurization apparatus comprising a diluting liquid mixing means for mixing a diluting liquid with an absorbent slurry. 2. A diluting liquid mixing means is branched from a water supply pipe for replenishing water to the liquid reservoir in order to maintain a constant level of the absorbing liquid in the liquid reservoir, and a tip thereof is connected to a slurry supply pipe. The flue gas desulfurization device according to claim 1, wherein the flue gas desulfurization device is constituted by a supplied water supply branch pipe. 3. The flue gas desulfurization apparatus according to claim 1, wherein the supply port at the tip of the slurry supply pipe is branched into a plurality of parts via a header and opened at appropriate plural places in the absorption tower.