JPH10202049A - Stack gas desulfurizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize oxidizing air and to miniaturize an oxidation tower and an oxidizing air blower. SOLUTION: This stack gas desulfurizer is provided with an absorption tower 3 and an oxidation tower 25. A liq. absorbent 1 in a reservoir 4 storing the supplied absorbent 1 is supplied to a spray nozzle 5 by a circulating pump 6, sprayed and brought into contact with an exhaust gas 9 to absorb and remove the sulfur dioxide in the exhaust gas 9 by the absorption tower 3. A part of the absorbent 1 having absorbed sulfur dioxide by contact with the exhaust gas 9 is introduced into the oxidation tower 25 and stored, the absorbent 1 is oxidized by the oxidizing air 16 from an oxidizing air blowing nozzle 14, and a part of the oxidized absorbent 1 is discharged to the outside in the oxidation tower 25. An air outlet pipe 26 provided at the upper part of the oxidation tower 25 is connected to an air blowing nozzle 24 furnished in the reservoir 4 of the absorption tower 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a flue gas desulfurization device.

[0002]

2. Description of the Related Art As shown in FIG. 2, a flue gas desulfurization apparatus which has been widely used for industrial purposes, as shown in FIG. 2, uses lime [NaOH] (limestone, slaked lime or quicklime) or magnesium oxide [Mg (OH) as an absorbent. ₂ ) is dissolved in water so that the absorbing liquid 1 is stored in a liquid reservoir 4 formed below the absorbing tower 3 by an absorbing liquid supply pipe 2, and a spray nozzle 5 is provided in the upper part of the absorbing tower 3. The absorption liquid 1 is taken out from the lower part of the liquid reservoir 4 and circulated to the spray nozzle 5 through a circulation pipe 7 by a circulation pump 6 for spraying.
To remove sulfur dioxide SO ₂ in the exhaust gas 9,
Exhaust gas 9 from which sulfur dioxide SO ₂ has been removed is discharged to the upper outlet 10
From the atmosphere.

[0003] Lime [Na
OH], the absorbing solution 1 and sulfur dioxide SO ₂
With sodium sulfite Na ₂ SO ₃ , and magnesium oxide [Mg (O
H) ₂ ], magnesium sulphite MgSO ₃
Is generated.

The absorbing solution 1 containing sodium sulfite Na ₂ SO ₃ or magnesium sulfite MgSO ₃ is COD
Due to the problem of (chemical oxygen demand), it cannot be discharged as it is.

For this reason, a drain pipe 12 provided with a flow control valve 11 is connected to the circulation pipe 7 for taking out the absorbent 1 from the lower part of the liquid reservoir 4 as described above. By connecting to the oxidation tower 13, a part of the absorption liquid 1 circulating in the circulation pipe 7 is supplied to the oxidation tower 13 through the drain pipe 12 and stored.

A plurality of oxidizing air blowing nozzles 14 are provided at the inner bottom of the oxidizing tower 13. The oxidizing air blowing nozzles 14 are provided outside the oxidizing tower 13 to suck and compress air. Oxidizing air 1 from oxidizing air blower 15
6 is supplied via an oxidizing air supply pipe 17.

As shown in FIG. 3, the oxidizing air blowing nozzle 14 is provided with a large number of small openings 18 facing downward so as to prevent clogging by solid matter generated in the absorbing liquid, and generates a large amount of fine bubbles 19. The oxidation tower 1
The bubbles 19 are brought into contact with the absorbing liquid 1 in 3 to oxidize the absorbing liquid 1.

The oxidizing air 16 used for oxidizing the absorbing liquid 1 is supplied to the air outlet pipe 2 connected to the upper end of the oxidizing tower 13.
The gas is supplied to the gas space 21 above the liquid reservoir 4 of the absorption tower 3 through the exhaust gas 9 and is discharged to the outside through the upper discharge port 10 together with the exhaust gas 9.

When sodium sulphite Na ₂ SO ₃ is contained in the absorption liquid 1 supplied into the oxidation tower 13, the oxidation by the oxidizing air 16 results in sodium sulfate Na ₂ SO ₄ as shown in the following formula I. ,

Embedded image_TwoSO_Three+ 1 / 2O_Two→ Na_TwoSO_Four... (I) Magnesium sulfite MgSO_ThreeContains
If oxidized by air 16
As shown in Formula II, magnesium sulfate MgSO _FourTona
And

Embedded image MgSO ₃ + 1 / 2O ₂ → MgSO ₄ (II) Thereby, both are rendered harmless and can be discharged.

Therefore, the absorption liquid 1 oxidized in the oxidation tower 13 and made harmless is supplied to the bottom of the oxidation tower 13 by the pump 2.
A discharge pipe 23 is connected to the discharge pipe 23 through the discharge pipe 2.

In the above-mentioned conventional flue gas desulfurization apparatus,
The absorbent 1 in the liquid reservoir 4 of the absorption tower 3 is circulated to the spray nozzle 5 by the operation of the circulation pump 6, and the exhaust gas 9 sent to the absorption tower 3 from the gas inlet 8 is sprayed from the spray nozzle 5. The sulfur dioxide SO ₂ is absorbed and removed by coming into contact with the absorbing solution 1 to be discharged, and then discharged from the upper discharge port 10 to the outside.

On the other hand, sulfur dioxide SO ₂
A part of the absorbing liquid 1 which has been absorbed and stored in the liquid reservoir 4 is taken out by the drain pipe 12 connected to the circulation pipe 7 and stored in the oxidation tower 13, and the operation of the oxidizing air blower 15 is performed. As a result, the oxidizing air 16 ejected from the oxidizing air blowing nozzle 14 forms a large amount of air bubbles 19 in the absorbing liquid 1, whereby the absorbing liquid 1 is oxidized.

When the absorption liquid 1 in the oxidation tower 13 contains sodium sulfite Na ₂ SO ₃ ,
The sodium sulfate Na ₂ SO _4, and the by oxidation with, if the absorbing liquid 1 contains magnesium sulfite MgSO ₃ is harmless absorption liquid becomes 1 magnesium sulfate MgSO _4, thereby the oxidation by oxidation air 16 .

The detoxified absorbent 1 can be discharged to the outside by the pump 22 through the discharge pipe 23.

The oxidizing air 16 supplied and jetted to the oxidizing air blowing nozzle 14 is partially oxidized in the oxidizing tower 13 to oxidize the absorbing liquid 1, and then is passed through an air outlet pipe 20. The gas is supplied to the gas space 21 above the liquid reservoir 4 of the absorption tower 3, and is discharged to the outside together with the exhaust gas 9 from the upper discharge port 10.

[0016]

When the absorption liquid 1 is brought into contact with the oxidizing air 16 to oxidize sodium sulfite Na ₂ SO ₃ or magnesium sulfite MgSO ₃ in the absorption liquid 1 as in the oxidation tower 13, The reaction efficiency is low because it is a reaction by contact between gas and liquid.
The oxidizing air 16 is supplied three to four times the stoichiometric air ratio.

Therefore, the oxygen in the oxidizing air 16 supplied to the oxidizing tower 13 is only slightly used in the reaction with the absorbing liquid 1 and is discharged from the air outlet pipe 20 with most of the oxygen remaining unreacted. Will be.

In the conventional apparatus, the oxidizing air 16 containing a large amount of oxygen from the air outlet pipe 20 is supplied to the gas space 21 above the liquid reservoir 4 of the absorption tower 3 as described above. As a result, the effective oxidizing air 16 is simply discharged to the outside together with the exhaust gas 9, and thus the oxidizing air 16 is not effectively used. Therefore, the oxidizing tower 13 has a large capacity. Or the size of the oxidizing air blower 15 needs to be increased.

The present invention has been made in view of the above-mentioned circumstances, and an exhaust gas desulfurization apparatus capable of effectively utilizing oxidizing air and thereby reducing the size of an oxidation tower and the size of an oxidizing air blower. It is intended to provide.

[0020]

SUMMARY OF THE INVENTION The present invention relates to a method of supplying an absorbing liquid in a liquid reservoir, in which the absorbing liquid is supplied and stored, to a spray nozzle by a circulating pump and spraying the absorbing liquid so that the absorbing liquid is brought into contact with the exhaust gas. An absorption tower that absorbs and removes sulfur dioxide, and a part of the absorbing solution that has absorbed sulfur dioxide by contact with exhaust gas is introduced and stored, and the absorbing solution is oxidized by oxidizing air from the oxidizing air blowing nozzle provided at the bottom. A flue gas desulfurization device comprising: an oxidation tower configured to discharge a part of the oxidized absorption liquid to the outside, and an air outlet pipe provided at an upper portion of the oxidation tower, The present invention relates to a flue gas desulfurization device characterized by being connected to a liquid reservoir air blowing nozzle provided in the liquid reservoir.

According to the above means, since the liquid reservoir of the absorption tower is made to act as a part of the oxidation tower, the capacity of the oxidation tower can be reduced or the capacity of the oxidation air blower provided in the oxidation tower can be reduced. The size can be reduced.

[0022]

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

FIG. 1 is an example of an embodiment of the present invention. In the figure, the portions denoted by the same reference numerals as those in FIG. 2 represent the same components, and the basic configuration is the same as that of the conventional device shown in FIG. The feature of the present example is the same as that shown in FIG. 1, but as shown in FIG. 1, a liquid reservoir air blowing nozzle 24 is provided in the liquid reservoir 4 of the absorption tower 3 to further reduce the capacity of the oxidation tower. An air outlet pipe 26 provided at an upper part of the nozzle 25 is connected to the liquid reservoir air blowing nozzle 24. In addition, as shown in FIG. 3, the liquid pool air blowing nozzle 24 blows out the oxidizing air 16 from the lower part and generates a large number of fine bubbles 19 as in the case of the oxidizing air blowing nozzle 14.

According to the above-described configuration, a part of the absorbent 1 in the liquid reservoir 4 that has been in contact with the exhaust gas 9 in the absorption tower 3 and has absorbed the sulfur dioxide is removed from the drain pipe 12 connected to the circulation pipe 7. The oxidizing air blower 15 sends the oxidizing air 16 to the oxidizing air blowing nozzle 14 through the oxidizing air blower 15 to generate a large amount of air bubbles 19 in the absorbing solution 1, whereby the sulfurous acid in the absorbing solution 1 is reduced. Oxidation of sodium Na ₂ SO ₃ or magnesium sulfite MgSO ₃ is performed.

At this time, since the reaction efficiency between the absorbing solution 1 and the oxidizing air 16 is low, the oxidizing tower 25 has three times the theoretical air ratio.
Since the oxidizing air 16 supplied to the air outlet pipe 26 still contains a large amount of oxygen, the oxidizing air 16 is supplied to the above-mentioned liquid reservoir air blowing section. By supplying the liquid to the nozzle 24, a large amount of bubbles 19 are generated in the absorbing liquid 1 in the liquid reservoir 4.

As a result, the sodium sulfite N generated in the absorbent 1 stored in the liquid reservoir 4 of the absorption tower 3
a ₂ SO ₃ or magnesium sulfite MgSO ₃ is oxidized by the oxidizing air 16 from the oxidizing tower 25.

Therefore, the liquid reservoir 4 of the absorption tower 3 acts as a part of the oxidation tower, and therefore, the sodium sulfite Na ₂ SO ₃ or magnesium sulfite MgSO _{3 in} the absorption liquid 1 guided to the oxidation tower 25 is formed. The concentration is reduced, so that the capacity of the oxidation tower 25 can be reduced, the capacity of the oxidizing air blower 15 can be reduced, and the power consumption of the oxidizing air blower 15 can be reduced.

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

[0029]

As described above, according to the flue gas desulfurization apparatus of the present invention, the liquid pool portion of the absorption tower is made to act as a part of the oxidation tower. An excellent effect that the capacity can be reduced or the capacity of the oxidizing air blower provided in the oxidation tower can be reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is an overall schematic configuration diagram of a conventional example.

3 is an enlarged view in the direction of arrow III in FIG. 2;

[Description of Signs] 1 Absorbing liquid 3 Absorption tower 4 Liquid reservoir 5 Spray nozzle 6 Circulation pump 9 Exhaust gas 14 Oxidation air injection nozzle 16 Oxidation air 24 Liquid reservoir air injection nozzle 25 Oxidation tower 26 Air outlet tube

Claims (1)

[Claims] 1. An absorption device for supplying and storing an absorbing liquid to a spray nozzle by a circulating pump and spraying the absorbing liquid to contact the exhaust gas to absorb and remove sulfur dioxide in the exhaust gas. A part of the absorbing solution that has absorbed the sulfur dioxide by contact with the tower and the exhaust gas is introduced and stored, and the absorbing solution is oxidized by oxidizing air from an oxidizing air blowing nozzle provided at a lower portion, and the oxidized absorbing solution is oxidized. A flue gas desulfurization apparatus comprising: an oxidation tower configured to discharge a part of the gas to the outside, wherein an air outlet pipe provided at an upper part of the oxidation tower is provided at a liquid pool part of the absorption tower. A flue gas desulfurization device connected to a partial air blowing nozzle.