JPH06142445A - Stack gas desulfurizer - Google Patents

Abstract

PURPOSE:To improve desulfurization efficiency, to eliminate the need for a thickener, dehydrator feeding tank and mother liquor tank and to reduce the site area and construction cost. CONSTITUTION:A supernatant tank 28 segmented by the partition wall 26 for interrupting the influence of the compressor 6 and agitator 7 and a side wall 27 and with the bottom communicating with a liq. reservoir 1 is formed at a part of the reservoir 1 of an absorption tower 5. A neutralizer 12 is injected into the lower part of the supernatant tank 28, and a part of the supernatant 29 at the upper part of the tank 28 is blown into a waste water treating device 24.

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.

[0002]

2. Description of the Related Art Conventionally, a flue gas desulfurization apparatus using lime as an absorbent generally absorbs the absorbent 2 in a liquid reservoir 1 formed at the bottom by operating a circulation pump 3 as shown in FIG. , The liquid pool of the absorption tower 5 for spraying and circulating the spray from the spray nozzle 4 arranged at the upper part and for discharging the exhaust gas supplied from the outside after contacting with the absorbent 2 sprayed from the spray nozzle 4 and then discharging it. A compressor 6 for supplying oxidizing air is connected to the part 1, and a stirrer 7 for stirring the absorbing liquid 2 in the liquid reservoir 1 is provided, and a supernatant liquid and a silo 8 are supplied from a mother liquor tank described later. Lime 9 supplied
Is provided to form an absorbent slurry 10 and to supply the absorbent slurry 10 to the liquid pool portion 1 of the absorption tower 5 by providing an absorbent slurry pit 11 from the bottom of the absorption tower 5 A part of the neutralizer 12 such as caustic soda supplied to the liquid reservoir 1 of the absorption tower 5 is supplied to the neutralizer tank 13 for mixing and stirring the absorbent 2 and the neutralizer 12. Is provided, a thickener 15 for concentrating the liquid 14 extracted from the neutralization tank 13 is provided, and a dehydrator supply tank 17 for supplying the liquid 16 concentrated by the thickener 15 and stirring the liquid 16 is provided. Machine supply tank 1
A dehydrator 20 for dehydrating the liquid 16 extracted from 7 to produce gypsum 19 is provided, and water 2 dehydrated by the dehydrator 20 is provided.
1, a filtrate pit 22 for supplying a part of the water 21 to the thickener 15 is provided, and a supernatant 23 is supplied from the thickener 15 and a part of the supernatant 23 is partially absorbed in the absorption tower. 5, a mother liquor tank 25 is provided for supplying the liquid reservoir 1 and the absorbent slurry pit 11 and sending the rest to the waste water treatment device 24.

In FIG. 3, reference numeral 18 denotes make-up water which is appropriately supplied to the absorption tower 5.

In the case of the flue gas desulfurization apparatus as described above, the absorption liquid 2 having a concentration of about 10% is circulated by the operation of the circulation pump 3, and the exhaust gas sent to the absorption tower 5 is sprayed from the spray nozzle 4. By contact with the absorbent 2,
After the sulfur oxide is absorbed and removed, it is discharged to the outside.

On the other hand, a part of the absorption liquid 2 which has absorbed the sulfur oxides from the exhaust gas is supplied to the neutralization tank 13 from the bottom of the liquid pool portion 1 of the absorption tower 5, and the neutralization agent is stored in the neutralization tank 13. 12 is mixed and stirred, and heavy metals such as fluorine and aluminum collected from the exhaust gas are precipitated to form a slurry together with gypsum, and the mixed and stirred liquid 14 is thickener 1
5 and concentrated in the thickener 15 to a concentration of about 20%, and the concentrated liquid 16 is sent to the dehydrator 20 via the dehydrator supply tank 17, where the water is removed in the dehydrator 20 and the gypsum 19 is removed. Are dehydrated and separated. This plaster 1
9 contains heavy metals such as fluorine and aluminum deposited in the neutralization tank 13. As a result, dissolved impurities in the desulfurization system liquid are reduced, and adverse effects on the desulfurization performance and the like can be excluded. In the dehydrator 20, it is most efficient to supply the slurry with a slurry concentration of 20%. This is because when the slurry concentration is 10%, the amount of water to be dehydrated is large, so that the dehydration takes a long time, and when the slurry concentration is higher than 20%, it becomes difficult to drain water from between the gypsum and the dehydration time does not become so short.

The water 21 dehydrated by the dehydrator 20 is returned to the thickener 15 through the filtrate pit 22, and the supernatant liquid 23 which is discharged when the liquid 14 is concentrated in the thickener 15 is stored in the mother liquor tank 25. After that, the liquid is supplied to the liquid pool portion 1 of the absorption tower 5 and the absorbent slurry pit 11 and is also sent to the waste water treatment device 24.

The supernatant liquid 23 supplied to the absorbent slurry pit 11 is kneaded with the lime 9 supplied from the silo 8 in the absorbent slurry pit 11 to form an absorbent slurry 10 in the liquid pool of the absorption tower 5. Supplied to part 1.

[0008]

However, in the flue gas desulfurization apparatus as described above, since the concentration of the absorbing liquid 2 in the absorption tower 5 is maintained at about 10%, the desulfurization efficiency is not very good, and moreover, Since the thickener 15, the dehydrator supply tank 17, and the mother liquor tank 25 are required, the site area for the flue gas desulfurization device is increased and the construction cost is increased.

In view of the above situation, the present invention provides a flue gas desulfurization apparatus capable of improving desulfurization efficiency and eliminating thickener, dehydrator supply tank, and mother liquor tank and reducing site area and construction cost. It is the one we are trying to provide.

[0010]

According to the present invention, an absorption liquid using lime in a liquid pool formed in a lower portion is sprayed from a spray nozzle arranged in the upper portion to be circulated and supplied from the outside. Exhaust gas is brought into contact with the absorption liquid sprayed from the spray nozzle, and then the liquid pool part of the absorption tower to be discharged is configured to blow the oxidizing air, and a stirrer for stirring the absorption liquid in the liquid pool part is provided, In a part of the liquid pool portion, a supernatant tank is formed which is defined by a partition wall for blocking the influence of the oxidizing air and the influence of a stirrer and a side wall of the absorption tower and in which the liquid pool portion and the bottom portion communicate with each other. It is characterized in that a neutralizing agent is injected into the lower part of the supernatant tank and a part of the supernatant liquid in the upper part of the supernatant tank is blown to a waste water treatment device.

[0011]

Therefore, when the exhaust gas is sent to the absorption tower while the absorption liquid having a concentration of about 20% is circulated, the exhaust gas comes into contact with the high-concentration absorption liquid sprayed from the spray nozzle, so that the sulfur oxidation is performed. After the substances are efficiently absorbed and removed, they are discharged to the outside.

On the other hand, if a part of the absorption liquid that has absorbed sulfur oxides from the exhaust gas is supplied to the neutralization tank and mixed and stirred with the neutralizing agent, the heavy metals such as fluorine and aluminum collected in the absorption tower are removed. By depositing as a solid content and sending the mixed and stirred liquid to a dehydrator, water is removed in the dehydrator, gypsum containing heavy metals such as fluorine and aluminum is dehydrated and separated, and dehydrated by the dehydrator. Water can be returned to the lower part of the supernatant tank.

Further, in the above-mentioned supernatant tank, the influence of the blowing of the oxidizing air and the influence of the stirrer are blocked by the partition wall. Therefore, if a neutralizing agent is supplied to the lower portion of the supernatant tank, heavy metals such as fluorine and aluminum can be supplied. The substances precipitate and settle together with gypsum, and as the supernatant liquid, a liquid containing few heavy metals such as fluorine and aluminum and very few dissolved impurities is formed in the upper part of the supernatant tank, and a part of the supernatant liquid is formed. Is sent to the wastewater treatment equipment.

As a result, the supernatant tank formed inside the absorption tower plays a role of a mother liquor tank in the conventional example, and the concentration of the absorption liquid is increased.
The thickener and dehydrator supply tank in the conventional example are also unnecessary.

[0015]

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

FIG. 1 shows an embodiment of the present invention.
The parts denoted by the same reference numerals as those in FIG. 3 represent the same things, and the basic structure is the same as that of the conventional one shown in FIG. 3, but the feature of this embodiment is shown in FIG. as,
A compressor 6 and a stirrer 7 are provided in a part of the liquid reservoir 1 of the absorption tower 5.
To form a supernatant tank 28 which is defined by a partition wall 26 and a side wall 27 of the absorption tower 5 and which communicates between the liquid reservoir 1 and the bottom, and the neutralizing agent 12 is placed below the supernatant tank 28. The point is that it is configured to inject and blow a part of the supernatant liquid 29 above the supernatant tank 28 to the wastewater treatment device 24.

Further, in this embodiment, the supernatant tank 28 is used.
To knead the supernatant liquid 29 supplied from the upper part and the lime 9 supplied from the silo 8 to produce the absorbent slurry 10 and to supply the absorbent slurry 10 to the liquid reservoir 1 of the absorption tower 5. An absorbent slurry pit 11 is provided to supply a part of the absorbent 2 circulated in the absorption tower 5 and the neutralizer 12 supplied to the liquid reservoir 1 of the absorption tower 5 and the lower part of the supernatant tank 28. A neutralization tank 13 is provided for mixing and stirring the absorption liquid 2 and the neutralizing agent 12 which are partially supplied, and a dehydrator 20 for dehydrating the liquid 30 extracted from the neutralization tank 13 to generate gypsum 19. An overflow pit 32 is provided for supplying the water 31 dehydrated by the dehydrator 20 and supplying a part of the water 31 to the lower portion of the supernatant tank 28.

If the top of the partition wall 26 is disposed above the liquid surface of the liquid reservoir 1 and the gas vent 33 is installed here, the supernatant tank 28 is degassed when the liquid is filled before starting the operation. It is not necessary and is convenient, and even if there is a fluctuation in the liquid level in the supernatant tank 28 due to fluctuations in the amount of liquid withdrawn from the supernatant tank 28, it will interlock with the liquid surface of the liquid pool 1 having a large area. There is an advantage that the fluctuation of the liquid surface is small. Also, the supernatant tank 28
Even if the top is lower than the liquid surface of the liquid reservoir 1, it can be used without any problem as long as the gas can be released during the liquid filling before the start of operation.

Since the structure is as described above, the concentration is about 20.
% Of the absorbing liquid 2 is circulated by the operation of the circulation pump 3, the exhaust gas is sent to the absorption tower 5, and the exhaust gas is
The sulfur oxide is efficiently absorbed and removed by coming into contact with the high concentration absorbent 2 sprayed from the spray nozzle 4, and then discharged to the outside.

Here, FIG. 2 is a line based on experimental results showing the desulfurization efficiency with respect to the liquid-gas ratio (liquid amount of the absorbing liquid 2 sprayed per unit amount of exhaust gas) when the concentration of the absorbing liquid 2 is changed. It is a figure, and it can be seen that the desulfurization efficiency is improved by increasing the concentration of the absorbing liquid 2 from 10% to 20%.

On the other hand, a part of the absorption liquid 2 which has absorbed the sulfur oxides from the exhaust gas is supplied to the neutralization tank 13 from the discharge side of the circulation pump 3, and in the neutralization tank 13, the liquid pool of the absorption tower 5 is collected. Part 1 and a part of the neutralizing agent 12 supplied to the lower part of the supernatant tank 28 are mixed and stirred, and heavy metals such as fluorine and aluminum collected in the absorption tower 5 are precipitated as a solid content,
The mixed and agitated liquid 30 is sent to a dehydrator 20, the moisture is removed in the dehydrator 20, and the gypsum 19 containing heavy metals such as fluorine and aluminum is dehydrated and separated.

The water 31 dehydrated by the dehydrator 20 is returned to the lower part of the supernatant tank 28 through the overflow pit 32.

Further, in the supernatant tank 28, the effect of the oxidizing air supplied from the compressor 6 and the effect of the agitator 7 are blocked by the partition wall 26, and the neutralizing agent 12 is placed below the supernatant tank 28. In this case, as in the neutralization tank 13, heavy metals such as fluorine and aluminum are deposited and settled together with gypsum, and the supernatant 29 is a liquid containing few heavy metals such as fluorine and aluminum and containing very few dissolved impurities. Is formed on the upper part of the supernatant tank 28, the supernatant liquid 29 is sent to the waste water treatment device 24, and a part of the supernatant liquid 29 is supplied to the absorbent slurry pit 11, and the upper part of the absorbent slurry pit 11 is used. A part of the clear liquid 29 is kneaded with the lime 9 supplied from the silo 8 and supplied as the absorbent slurry 10 to the liquid reservoir 1 of the absorption tower 5.

As a result, the supernatant tank 28 formed inside the absorption tower 5 plays the role of the mother liquor tank 25 in the conventional example, and at the same time, the concentration of the absorbent 2 is increased, so that in the conventional example. The thickener 15 and the dehydrator supply tank 17 are also unnecessary.

Thus, the desulfurization efficiency can be improved, and the thickener 15, the dehydrator supply tank 17, and the mother liquor tank 25, which have been conventionally required, can be eliminated, and the site area and the construction cost can be reduced. It is possible to plan.

The flue gas desulfurization apparatus of the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0027]

As described above, according to the flue gas desulfurization apparatus of the present invention, the desulfurization efficiency can be improved, and the thickener, the dehydrator supply tank, and the mother liquor tank are unnecessary, and the site area and the construction cost can be reduced. The excellent effect of achieving reduction can be achieved.

[Brief description of drawings]

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

FIG. 2 is a diagram showing the relationship between liquid gas ratio and desulfurization efficiency.

FIG. 3 is a schematic diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid pool part 2 Absorption liquid 4 Spray nozzle 5 Absorption tower 6 Compressor 7 Stirrer 8 Silo 9 Lime 10 Absorbent slurry 11 Absorbent slurry pit 12 Neutralizer 13 Neutralization tank 19 Gypsum 20 Dehydrator 24 Wastewater treatment device 26 Partition wall 27 Side wall 28 Supernatant tank 29 Supernatant liquid 30 Liquid 31 Water 32 Overflow pit

Claims (1)

[Claims] 1. An absorption liquid using lime in a liquid pool formed in a lower part is sprayed from a spray nozzle arranged in the upper part and circulated, and exhaust gas supplied from the outside is sprayed from the spray nozzle. In the liquid pool part of the absorption tower to be discharged after being brought into contact with the absorbing liquid, a stirring machine for stirring the absorbing liquid in the liquid pool part is provided with the oxidizing air, and a part of the liquid pool part is provided. Forming a supernatant tank defined by a partition wall that blocks the influence of the blowing of the oxidizing air and the influence of a stirrer and a side wall of the absorption tower, and connecting the liquid reservoir portion and the bottom portion to each other. A flue gas desulfurization device, characterized in that a hydrating agent is injected and a part of the supernatant liquid in the upper part of the supernatant liquid tank is blown to a wastewater treatment device.