JP3219493B2 - High-performance flue gas desulfurization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for desulfurizing an exhaust gas containing sulfur oxides such as an exhaust gas from a coal-fired boiler. It is intended to provide a high-performance flue gas desulfurization method that can economically desulfurize up to.

[0002]

2. Description of the Related Art At present, many flue gas desulfurization methods, such as a wet lime method, a wet soda method, and a wet magnesium hydroxide method, have already been put into practical use as desulfurization methods for exhaust gas containing sulfur oxides. As an example, a desulfurization method by the wet lime method, which occupies the mainstream of large-scale flue gas desulfurization equipment of a commercial thermal power plant, will be described with reference to FIG.

[0003] Exhaust gas 2 containing sulfur oxides such as coal-fired boiler exhaust gas is led to a desulfurizer 1. In the desulfurization apparatus 1, a slurry-like absorbent 6 containing CaSO ₄ .2H ₂ O generated by a reaction with CaCO ₃ sent from a passage 15 is ejected from a nozzle 3 via a passage 10 by a pump 9.
The slurry-like absorbing liquid 6 comes into gas-liquid contact with the exhaust gas containing high concentration of sulfur oxide in the absorbing section 4 filled with the grid, and the CaSO _4.
2H ₂ O is produced and desulfurized. The reaction in this absorption section is as follows. _{SO 2 + H 2 O = H} + + HSO 3 - ··· (1) ( ^{_{absorption) H + + HSO 3 - +}} 1 / 2O 2 = 2H + + SO 4 2- ··· (2) ( oxidized) CaCO ₃ ⁺ 2H + + SO ₄ ²⁻ + H ₂ O = CaSO ₄ .2H ₂ O + CO ₂ (3) (neutralization)

In the tank 5, the fuel is supplied from a path 8.
Slurry-like absorbent 6
Injected into the air as fine bubbles, sulfite ions (HS
O_Three ^-) To promote the oxidation of SO_TwoThe absorption rate of
With CaCO_ThreeCaSO by neutralization reaction with_Four・ 2
H_TwoGenerate O. The reaction in this tank 5 is as follows
It is a cage. H⁺+ HSO_Three ^-+ 1/2 O_Two= 2H⁺+ SO_Four ^2- ... (4) (oxidation) CaCO_Three+ 2H⁺+ SO_Four ^2-+ H_TwoO = CaSO_Four・ 2H_TwoO + CO_Two ... (5) (neutralization)

[0005] A part of the slurry-like absorbent 6 containing CaSO ₄ · 2H ₂ O is withdrawn from a passage 11 and separated into solid and liquid by a centrifugal separator 12 to collect by-product gypsum 13. The liquid after the solid-liquid separation is returned to the tank through the path 14. On the other hand, the exhaust gas from which most of the sulfur oxides have been removed is discharged from the flue 16
The mist is guided to a fine water droplet collector (mist kitcher) 17 through the mist removing section, and is discharged as an exhaust gas 22 after removing the mist. The mist collected by the mist kitcher 17 passes through the path 18
, And is returned to the tank 5 via the pump 20 and the path 21 as makeup water.

[0006]

The problem of acid rain is particularly serious at present, when the protection of the global environment is being emphasized, and the spread of flue gas desulfurization equipment is being promoted worldwide.
Improvements in the development of economical and high-performance flue gas desulfurization technology have been made, but the conventional technology has limited desulfurization performance. For example,
For exhaust gas containing high concentration sulfur oxides of several thousand ppm such as coal-fired boiler exhaust gas, grid (1m height x 4)
L / G in a desulfurization unit by wet lime method filled with
By operating the desulfurization device under the conditions of {amount of alkali absorption liquid (liter / hr) / flow rate of processing gas (m ³ N / hr)} = 10 to 20 and pH = 5 to 7, the desulfurization rate is about 95%. can get. Even in such high-performance desulfurization equipment, if the sulfur oxide concentration in the exhaust gas is high, several tens of ppm of sulfur oxides will be discharged into the atmosphere. Efforts are needed to further reduce the sulfur oxide concentration, and it would be more ideal if the sulfur oxide concentration could be reduced to levels below 1 ppm. The means can be solved by using a conventional two-column desulfurization apparatus in which two series of desulfurization apparatuses are arranged, but it is expensive and not economical. Therefore, a more economical and high-performance desulfurization system is desired.

On the other hand, since SO ₃ mist becomes a problem when in acid rain is ultrafine particles is poor removal performance in the conventional desulfurizer. Therefore, when desulfurizing the sulfur oxide concentration to a level of 1 ppm or less, it is necessary to consider not only the improvement of the absorption rate of SO ₂ but also the removal of SO ₃ .

In view of the above technical level, the present invention provides a method for desulfurizing both SO ₂ and SO ₃ sulfur oxides, which will be required as a measure against acid rain in the future, more economically and with high performance.
That is, the sulfur oxides (SO ₂ and S
It is an object of the present invention to provide a method for achieving an extremely high desulfurization performance capable of reducing the emission concentration level of O ₃ ) to 1 ppm or less.

[0009]

According to the present invention, (1) a combustion exhaust gas containing sulfur oxides is led to a desulfurization device,
A first desulfurization step of removing most of the sulfur oxides in the exhaust gas by an absorbent using a Ca-based alkaline substance as an absorbent,
Sulfur remaining in the exhaust gas by spraying an alkali absorbing solution by installing a spraying device at the upstream of the fine water droplet collector attached to the outlet of the absorption tower of the desulfurization device and facing the gas flow. By a second desulfurization step of removing oxides, a high-performance flue gas desulfurization method for performing two-step desulfurization, wherein Na ₂ CO ₃ is used as an absorbent in the second desulfurization step.
Atomized from the above spraying device using the alkaline absorbing solution containing, and the absorbing solution contained in the exhaust gas from the second desulfurization step.
And then mixed with the absorbent of the first desulfurization step,
A high-performance flue gas desulfurization method characterized by improving the ionic strength of the absorbent in the desulfurization step ; (2) gas-liquid contact between the combustion exhaust gas containing sulfur oxides and the absorbent using a Ca-based alkaline substance as an absorbent; A first desulfurization step for removing most of the sulfur oxides in the exhaust gas by the method, and a second desulfurization step for further increasing the desulfurization rate by spraying an alkaline absorbing solution containing Na ₂ CO ₃ onto the exhaust gas from the first desulfurization step. a step seen including, contained in exhaust gas from the second desulfurization step
Liquid mist collected in the first desulfurization step
To improve the ionic strength of the absorbent in the first desulfurization step , and (3) spraying the absorbent in the second desulfurization step with air and absorption high-performance flue gas desulfurization method (1) or (2) characterized in that it is a two-fluid spray simultaneously spraying liquid, (4) spraying of the absorbing liquid in the second desulfurization step, ultrasonic spraying device (1) or the above (1),
(2) High-performance flue gas desulfurization method.

[0010]

The flue gas containing SO ₂ and SO ₃ is led to the existing desulfurization process, and for example, CaCO ₃ is used as an absorbent,
Most of the absorber and the gas-liquid contact is not SO ₂ absorbing and removing. The desulfurization rate is the exhaust gas load and L / G {Alkaline absorption liquid amount (liter / hr) / processing gas flow rate (m ³ N / hr)}
The ratio is slightly different depending on the ratio, but is about 95%. Next, the SO ₂ and SO ₃ that could not be absorbed and removed by the existing desulfurization unit are sprayed in a two-stage desulfurization system in which atomization of alkali absorption liquid is sprayed by a sprayer installed in the flue section at the outlet of the absorption tower of the desulfurization unit. Thus, desulfurization can be performed more economically and efficiently.

[0011] On the other hand, the SO _3, is temporarily aggregating and enlarging the alkaline absorption liquid SO ₃ mist is miniaturized, mostly in the installed water microdroplets collector after flow is collected. By this effect, the concentration of sulfur oxides (SO ₂ and SO ₃ ) at the outlet of the desulfurization facility of the present invention can be suppressed to a low concentration level of 1 ppm or less.

That is, in the conventional grid filling method, an absorption reaction occurs at the wetted portion of the grid surface, the gas-liquid contact area is small, and L / G = 1 to improve desulfurization performance.
Although it was necessary to increase the alkaline absorption liquid to 0 to 20 as described in the present invention, the alkali absorption liquid was atomized by a spray device (for example, 30 to 300 μm).
m), the surface area of the droplet increases and the gas-liquid contact area increases. Therefore, when L / G is about 0.05 to 2 (liter / m ³ N), the SO ₂ absorption performance is sufficiently exhibited, and the amount of the spray liquid can be reduced. Coal exhaust gas containing such high concentrations of SO ₂ of the boiler exhaust gas to remove most of the SO ₂ gas in the first desulfurization step according to the conventional desulfurization apparatus used, the obtained high-quality by-product, in the first desulfurization step The residual SO ₂ gas that could not be removed is subjected to two-stage desulfurization by a spraying device, which is the second desulfurization step,
Desulfurization performance can be greatly improved compared to the conventional method,
Moreover, since the SO ₂ load is low in the second desulfurization step, it is possible to sufficiently remove SO _{2 in a} region where the concentration of the alkali absorbing solution is low.

Therefore, as in the present invention, by adopting a two-stage desulfurization system, the cost can be reduced and the system can be simplified as compared with installing two conventional desulfurization units, and the economic effect is extremely great. It is.

The alkali absorbing solution used in the spraying device in the second desulfurization step is an alkali absorbing solution containing Na ₂ CO ₃ . Here, the absorption liquid used in the first desulfurization step may be used as a part of the alkali absorption liquid used in the second desulfurization step . In particular, when this Na ₂ CO ₃ absorbing solution is used, SO ₂
By absorbing solution became Na ₂ SO ₄ to absorb is returned to the first desulfurization step, increasing the ionic strength in the first desulfurization step, and the dissolution rate of CaCO ₃ becomes large, the absorption rate of SO ₂ The synergistic effect of improving is produced. In addition, CaSO ₄ scattered from the first desulfurization step adheres to the fine water droplet collector and causes scaling, but as in the present invention, by using a Na ₂ CO ₃ absorbent in the second desulfurization step ,
The substitution reaction between CaSO ₄ and Na ₂ CO ₃ results in CaSO 4
_{Since 4} replaces CaCO ₃ , an effect of preventing scaling of the fine water droplet collector can be obtained.

As the alkali absorbing solution used in the second desulfurization step, an alkali absorbing solution containing Na ₂ CO ₃ is used. However, even if the process is returned to the first desulfurization step, it is used in a region where the SO ₂ load is extremely low. Since the concentration is small, the purity of the by-product produced in the first desulfurization step has no particular problem.

On the other hand, SO which is particularly problematic in acid rain_ThreeMiss
Are ultra-fine particles and can be removed with conventional desulfurization equipment.
Performance was poor, but fine suction from the spray device according to the present invention.
By spraying the collected liquid, SO_ThreeMist is temporarily agglomerated
It can be enlarged, and it can be largely
Fractions are collected and sulfur oxides (SO _Two
And SO_ThreeThe emission concentration level of 1) or less
And extremely high desulfurization performance is exhibited.

As the spraying device, a spraying nozzle can be used, but usually only 30 minutes by spraying the liquid from a single nozzle.
It is difficult to produce fine particles of １００100 μm, and it is generally better to use a two-fluid spray nozzle that sprays air and liquid simultaneously. This two-fluid spray nozzle has a narrow tip, is easily blocked by slurry-like absorbing liquid and dust, and requires a large amount of high-pressure air (air consumption rate 30 to 50).
wt%), it is preferable to use an ultrasonic spraying device as the spraying device. An ultrasonic spraying device is a device that generates a capillary wave or cavitation bubbles specific to a frequency on the liquid surface or in the liquid by vibrating energy of, for example, 30 to 100 kHz to divide the liquid, and the liquid supply may be performed at a low pressure, and the liquid may be supplied from outside. Since compressed air is not required and frequency-specific liquid particles can be obtained, it is suitable for atomization spraying of the absorbing liquid. Further, the ultrasonic atomizer has a feature that the droplet spectrum is almost constant in the entire flow rate range and the particle size distribution width is narrower than the two-fluid spray level. This has very important implications. That is, even if the average particle diameter is the same, if the particle size distribution width is wide like a two-fluid spray nozzle, the mixing ratio of large particles increases, and the performance deteriorates. Alkaline absorbing liquid scattered in the downstream part because it could not be collected by the collector,
It is also a cause of secondary pollution. The ultrasonic spraying device may be any type of spraying such as thin-walled hollow cylindrical horn spraying, bending wave spraying, and standing wave spraying. If the ultrasonic spraying device can efficiently atomize finely, the type is particularly limited. is not.

[0018] As the alkali absorption solution used in the spraying device
It can be used NaO H in addition to Na ₂ CO _3.

One embodiment of the method of the present invention will be described with reference to FIG. Exhaust gas 1 containing sulfur oxides (SO ₂ and SO ₃ ) is led to a desulfurizer 2. An alkaline absorbing solution (here, CaCO ₃ will be described as an example) 3 attached to the lower part of the desulfurization device 2 is supplied to the inlet of the desulfurization device 2 by a circulation pump 4, sprayed by a nozzle 5, and sulfur-oxidized. A gas-liquid contact reaction is performed with the exhaust gas 1 containing substances to desulfurize. This feeling
Grids 6 are stacked in multiple stages to increase the liquid contact efficiency.

The exhaust gas 1a that could not be completely removed is led to a fine water droplet collector 7 installed downstream of the desulfurizer.
Here, a spray nozzle 8 for atomizing and spraying an alkali absorbing liquid is installed upstream of the collector 7 so that the exhaust gas 1a containing residual SO ₂ is again absorbed and reacted.
Here, the alkali absorbing liquid 3 ′ put into the tank 11 is supplied to the spray nozzle 8 by the spray pump 9, and is brought into gas-liquid contact with the exhaust gas 1 a that is finely divided and contains residual SO ₂ , and is brought into a low concentration level (1 ppm). Below).

On the other hand, SO ₃ is coagulated and enlarged by the fine particles sprayed from the spray nozzle 8, and is almost completely removed by the fine water droplet collector 7. The collector 7
Since a drain is naturally generated in the lower part, the drain is collected by the hopper 10 and returned to the tank 11.

The pump 12 is a preliminary pump in the case of using either the alkali absorbing solution 3 or the alkali absorbing solution 3 ', and is also a pump considering the maintenance of the level of the filling solution in the desulfurization device. A line 13 is provided in which a new alkali absorbent can be introduced from another line. In addition, 14 is a stirring motor, 15 is a stirring blade, 1b
Indicates a purified gas.

One embodiment of the method of the present invention will be described with reference to FIG. Exhaust gas 2 containing sulfur oxides such as coal-fired boiler exhaust gas is led to an existing desulfurization unit 1. Desulfurization device 1
Then, the slurry-like absorbing liquid 6 containing CaSO ₄ .2H ₂ O generated by the reaction with CaCO ₃ sent from the passage 15 is ejected from the nozzle 3 through the passage 10 by the pump 9. The slurry-like absorbing liquid 6 comes into gas-liquid contact with the exhaust gas containing the sulfur oxide of the item concentration in the absorbing section 4 filled with the grid, and the CaSO
₄ · 2H generating and desulfurize ₂ O.

In the tank 5, air supplied from a passage 8 is blown as fine bubbles into the slurry-like absorbing liquid 6 by an arm-rotating sparger 7, and sulfite ions (HSO
₃ ^- The oxidized promote), CaSO ₄ · 2H by neutralization reaction with CaCO ₃ with improving the absorption rate of SO ₂
Produces ₂ O.

A part of the slurry-like absorbing liquid 6 containing the generated CaSO ₄ .2H ₂ O is withdrawn from the passage 11, separated into solid and liquid by the centrifugal separator 12, and the by-product gypsum 13 is recovered. The liquid after the solid-liquid separation is returned to the tank 5 through the path 14. On the other hand, the exhaust gas from which most of the sulfur oxides have been removed is discharged from the flue 16
Through the ultrasonic spraying device 23.

[0026] The ultrasonic atomizing device 23, N a ₂ CO ₃ that will be supplied from the path 25 through the tank 19, is supplied as an alkaline absorbing solution through a pump 20 and accounting 24 are miniaturized spray. The exhaust gas from which residual sulfur oxides have been removed by spraying the alkali absorbing liquid is discharged to a fine water droplet collector 17.
After being guided by the mist and removing the mist, it is discharged as exhaust gas 22.

The mist collected by the fine water droplet collector 17 is extracted to a tank 19 through a path 18. A part of the alkali absorbing liquid drawn out to the tank 19 is returned to the tank 5, which is the first desulfurization step, via the pump 20 and the path 21 to increase the ionic strength of the first desulfurization step absorbent to improve the activity. measure.

On the other hand, when the absorption solution 6 of the existing desulfurization device is used as a part of the alkali absorption solution used in the ultrasonic spraying device 23, the alkali absorption solution is supplied to the tank 19 via the pump 26 and the path 27. Used as part of

[0029]

For EXAMPLES Reference Example 1 coal combustion exhaust gas, the following results were tested according to the way shown in FIG. Coal combustion amount 25kg / hr
Directing exhaust gas 200m ³ N / hr generated from the combustion furnace to the dry denitrator with ammonia catalytic reduction method, then cooled to 0.99 ° C. through a heat exchanger, was treated with dry dust collector, it was shown in FIG. 1 It had guiding the desulfurization apparatus that is configured by law. However, the spray nozzle 8 was not used. The operating conditions of the desulfurizer at this time are as shown in Table 1 below.

[0030]

[Table 1]

Under the above conditions, the SO ₂ concentration at the outlet of the absorption tower was 50 ppm, the desulfurization rate was 95%, and the SO ₃ concentration was 18%.
→ 14 ppm, about 8% removed in the absorption tower.

This residual sulfur oxide (SO ₂ = 50 pp)
(m, SO ₃ = 14 ppm) The exhaust gas was sprayed with an alkali absorbing solution from a spray nozzle 8 upstream of the fine water droplet collector 7 to perform two-stage absorption. FIG. 3 shows the spray conditions at that time together with the results.

As can be seen from FIG. 3 above, it was confirmed that the desulfurization performance was improved by increasing L / G, and that the performance was further improved as the spray particle diameter became smaller. For example, the desulfurization performance at each spray particle diameter when L / G = 0.3 (60 L / m ³ N) is as shown in Table 2 below.

[0034]

[Table 2] From the above results, it was confirmed that when the spray particle diameter was 50 μm or less and the L / G ratio was 0.3 or more, the SO ₂ concentration was 1 ppm or less. By further increasing the residence time of the spray particles, the SO ₂ concentration can be reduced to 1 ppm or less with a smaller L / G.

[0035] On the other hand, the SO ₃ mist, typically, 50-55 ° C. at desulfurizer, has a dew point or less, but in theory it should be collected, SO ₃ particle size of the mist is submicron (1 μm or less), it is not completely removed, and as described above, only about 8% is collected in the desulfurization apparatus at present. Therefore, as a result of improving the collection efficiency of the fine water droplet collector 7 by making the spray liquid finer under the above spraying conditions and coagulating and expanding the SO ₃ mist, L / G = 0.3 It was also confirmed that SO ₃ was almost completely removed at the outlet of the fine water droplet collector 7 at the spray particle diameter of.

Example 1 A test using the method of the present invention shown in FIG. 2 was performed on coal combustion exhaust gas, and the following results were obtained. 25kg of coal combustion
200 m ³ N / hr exhaust gas generated from a combustion furnace
Guidance for dry denitration apparatus with ammonia catalytic reduction method, then cooled to 0.99 ° C. through a heat exchanger, was treated with dry dust collector, had guiding the desulfurization apparatus that is configured from the process of the present invention shown in FIG. 2 . The operating conditions of the desulfurizer at this time are as shown in Table 3 below.

[0037]

[Table 3]

Under the above conditions, the desulfurization rate in the first desulfurization step was 95%, the SO ₂ concentration at the outlet of the absorption tower was 50 ppm,
The O ₃ concentration was 14 ppm.

This residual sulfur oxide (SO ₂ = 50 pp)
m, was SO ₃ = 14 ppm) was sprayed Na ₂ CO ₃ 2wt% solution in an ultrasonic spraying device with the exhaust gas in the second desulfurization step comprising performing the two-step desulfurization. FIG. 4 shows the test results.
As is clear from FIG. 4, the desulfurization rate increases with an increase in L / G, and increases as the spray particle diameter decreases.
Needless to say, the longer the residence time of the particles (the time during which the spray particles are in contact with the exhaust gas), the higher the desulfurization rate. For example, particle residence time 0.3 sec, L / G =
The desulfurization rate for each spray particle size at 0.3 L / m ³ N is as shown in Table 4 below.

[0040]

[Table 4]

From the above results, the sulfur oxide concentration was set to 1 pp
m or less, if the spray particle diameter is 50 μm, L
/G=0.3 l / m ³ N or more, and 70 μm can be achieved by setting L / G = 0.4 l / m ³ N or more. By further increasing the residence time of the spray particles, the sulfur oxide concentration can be reduced to 1 ppm or less with a smaller L / G.

On the other hand, SO_ThreeFor mist, mist grains
Existing because the diameter is submicron (less than 1μm)
Only about 10% is collected in the desulfurization equipment of
At present, as in the present invention, the alkali absorption liquid is finer
And SO around it_ThreeTo make the mist coagulated and enlarged
Collision collection is possible with a fine water droplet collector installed in the downstream
No, SO_ThreeTrapping efficiency is improved. For example, L / G
= 0.3 liter / m ^ThreeN at each spray particle size under the condition of N
SO_ThreeAs a result of measuring the collection efficiency of
Also SO_ThreeIs almost completely collected.
Thus, the effectiveness of the present invention was proved.

In this embodiment, the ultrasonic spraying device was installed at the exit flue of the absorption tower of the existing desulfurization device.
It can be installed in existing desulfurization equipment.

[0044]

The SO ₂ absorption rate of the conventional wet lime-gypsum method flue gas desulfurization apparatus was about 95%, and the removal of SO ₃ was not considered at all. However, according to the method of the present invention, SO ₂ and SO ₃ were removed. Can be desulfurized to a level of 1 ppm or less, which is 99% in terms of desulfurization rate.
The above can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a reference example of a high-performance flue gas desulfurization method of the present invention.

FIG. 2 is an explanatory view of one embodiment of the high-performance flue gas desulfurization method of the present invention.

FIG. 3 is a table showing the effects of one reference example of the present invention.

FIG. 4 is a table showing effects of one embodiment of the present invention.

FIG. 5 is an explanatory view of one embodiment of a conventional flue gas desulfurization method.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naohiko Ugawa 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Inside the Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Mitsuyasu Honda Kannon-Shimmachi 4 No. 6-22 Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Koichiro Iwashita 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Heavy Industries, Ltd. Headquarters (56) References JP-A-3-221119 (JP, A) JP-A-63-97216 (JP, A) JP-A-63-242322 (JP, A) JP-A-51-13380 (JP, A) JP-A-51-104477 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) B01D 53/50 B01D 53/34 ZAB B01D 53/77

Claims (4)

(57) [Claims] 1. A first desulfurization step in which a combustion exhaust gas containing a sulfur oxide is guided to a desulfurization device, and a majority of the sulfur oxide in the exhaust gas is removed by an absorbing solution containing a Ca-based alkali substance as an absorbent; Sulfur oxides remaining in the exhaust gas by spraying the alkali absorbing solution by installing a spray device in the gas flow direction or facing the gas flow upstream of the fine water droplet collector attached to the outlet of the absorption tower of the device And a second desulfurization step of removing sulfur. A high-performance flue gas desulfurization method for performing two-step desulfurization, wherein Na _{2 is} used as an absorbent in the second desulfurization step.
Miniaturization sprayed from the spray device using an alkaline absorbing solution containing CO _3, contained in the exhaust gas from the second desulfurization step
Collect the absorbent mist and mix it with the absorbent in the first desulfurization step.
And improving the ionic strength of the absorbent in the first desulfurization step . 2. A first desulfurization step of removing most of the sulfur oxides in the exhaust gas by gas-liquid contact between a combustion exhaust gas containing a sulfur oxide and an absorbing solution containing a Ca-based alkaline substance as an absorbent. A second desulfurization step of further increasing the desulfurization rate by spraying an alkali absorption liquid containing Na ₂ CO ₃ onto the exhaust gas from one desulfurization step, and recovering the absorbent mist contained in the exhaust gas from the second desulfurization step A high-performance flue gas desulfurization method comprising mixing with the absorption liquid in the first desulfurization step to improve the ionic strength of the absorption liquid in the first desulfurization step. 3. The spraying of the absorbing solution in the second desulfurization step is performed by air.
It is a two-fluid spray that sprays water and absorbing liquid at the same time.
The high-performance flue gas desulfurization method according to claim 1 or 2, wherein 4. The spraying of the absorbing liquid in the second desulfurization step is performed by using a supersonic
2. Spraying by a wave spraying device.
Or the high-performance flue gas desulfurization method according to 2.