KR20190102764A - Wet flue gas desulfurization apparatus and wet flue gas desulfurization method - Google Patents

Abstract

The present invention relates to a wet flue gas desulfurization apparatus and method which can enhance the reactivity of limestone and enhances the desulfurization efficiency by bringing the flue gas and an absorption solution containing limestone (CaCO_3) into gas-liquid contact and bringing the same to be in contact with an alkaline solution separately at the same time for the absorption of sulfur oxides (SO_x).

Description

WET FLUE GAS DESULFURIZATION APPARATUS AND WET FLUE GAS DESULFURIZATION METHOD}

The present invention relates to a wet flue gas desulfurization apparatus and a wet flue gas desulfurization method, and more particularly, to an exhaust gas in contact with an absorption solution containing limestone (CaCO 3) and a gas-liquid solution to absorb sulfur oxides (SOx). The present invention relates to a wet flue gas desulfurization apparatus and method capable of improving the reactivity of limestone and increasing the desulfurization efficiency by gas-liquid contacting separately from the solution.

In the boiler, combustion is carried out by injecting fossil fuel, such as coal, and air containing excess oxygen, and as a result of combustion, fly ash, carbon dioxide (CO2), nitrogen oxides (NOx), and sulfur oxides ( By-products such as SOx), carbon monoxide (CO), and unburned carbon powder (HC) are generated together with heat, and unreacted nitrogen (N2) and oxygen (O2) remain.

As such, when the fuel containing sulfur is burned, sulfur is released to the atmosphere in the form of sulfur dioxide (SO2), except that it is attached to ash. This sulfur dioxide causes air pollution and causes acid rain on the earth, which has a detrimental effect on the environment as well as the human body and animals.

To this end, large-scale incineration plants and power plants have been usually equipped with an exhaust gas desulfurization unit, most of which are wet flue gas desulfurization units.

In a wet desulfurization process, the exhaust gas is gas-liquid contacted with an absorbing fluid containing an alkali such as lime, whereby sulfur dioxide is absorbed and removed from the exhaust gas. At this time, although the gas is classified into various types according to the gas-liquid contact method of the exhaust gas and the absorbing fluid, a spray method of contact is widely used worldwide.

As a result, sulfur dioxide absorbed from the exhaust gas forms sulfite in the absorbing fluid, which is typically oxidized by blowing air into the absorbing fluid to form gypsum as a byproduct.

That is, a wet flue gas desulfurization device is a type of so-called oxidation tank, where air is blown into the tank, where the air comes into contact with an absorbing fluid with absorbed sulfur dioxide inside the tank.

Looking at the conventional wet flue gas desulfurization apparatus disclosed in the Republic of Korea Utility Model Publication No. 1998-0030926, the exhaust gas is introduced into the absorption tower (1) through the inlet duct, the absorption tower (1) in the circulation pump (3) The absorbing liquid containing calcium carbonate supplied by the spray is sprayed in the spray nozzle 2 to make gas-liquid contact between the absorbing liquid and the exhaust gas. The absorbent liquid selectively absorbs sulfur dioxide in the exhaust gas to produce calcium sulfite, and the calcium sulfite (CaSO3) in the absorbent liquid is oxidized by oxygen in the air supplied to the absorption tower circulation tank 4 by the air intake pipe 6. To produce gypsum.

However, in the related art, when the concentration of sulfur oxide (SOx), dust, and the like contained in the exhaust gas flowing into the absorption tower 1 is high, the reactivity of limestone in the absorbent liquid is lowered. It is necessary to inject excessive limestone, there is a problem that the operating cost of the plant, such as a power plant is increased.

Korean Utility Model Publication No. 1998-0030926 (August 17, 1998 release)

The present invention is to improve the reactivity of limestone and increase the desulfurization efficiency by contacting the exhaust gas with the absorption liquid containing limestone (CaCO3) and gas-liquid contact with the alkaline solution separately for the absorption of sulfur oxides (SOx) of the exhaust gas. It is an object of the present invention to provide a wet flue gas desulfurization apparatus and a desulfurization method.

The present invention for solving the above problems, the absorption tank in which the absorption solution containing limestone (CaCO3) is stored, the absorption tower extending to the upper portion of the absorption tank, the exhaust gas inlet duct provided on one side of the absorption tower And an exhaust gas outlet duct provided on the other side of the absorption tower, a first injection unit installed in the absorption tower for injecting the absorption liquid, and an absorption solution in the absorption tank to the first injection unit. A circulation pump, a second injection unit installed in the absorption tower for injecting an alkali solution, an alkali supply unit for supplying an alkali solution to the second injection unit, and an oxygen supply pipe for supplying an oxygen-containing gas to the absorption tank; Provide a wet flue gas desulfurization system.

The exhaust gas introduced into the inlet duct may be in primary contact with the alkali agent solution injected by the second injector, and may be in secondary contact with the absorption solution injected by the first injector.

The alkaline agent may include at least one of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) 2), magnesium hydroxide (Mg (OH) 2).

The alkaline agent supply unit may include a storage tank in which the alkaline agent solution is stored and a supply pump for supplying the alkaline agent solution stored in the storage tank to the second injection unit.

A flow rate control valve may be installed on an alkaline agent supply line through which an alkaline agent solution is supplied from the storage tank to the second injection unit.

In addition, the control unit for controlling the injection amount of the alkali solution is injected through the second injection unit may be further included.

The flow control valve may be an electric valve.

The apparatus may further include a concentration meter for measuring the sulfur dioxide concentration of the exhaust gas introduced into the inlet duct.

The controller may increase the injection amount of the alkaline agent solution injected through the second injection unit when the sulfur dioxide concentration of the exhaust gas measured by the concentration meter exceeds a reference value.

The control unit may reduce the injection amount of the alkaline agent solution injected through the second injection unit when the sulfur dioxide concentration of the exhaust gas measured by the concentration meter does not exceed a reference value.

In addition, according to another embodiment of the present invention, it may further include a PH meter for measuring the pH of the absorption solution in the absorption tank.

The control unit may increase the injection amount of the alkaline agent solution injected through the second injection unit when the pH of the absorption solution measured by the PH measuring device does not exceed a reference value.

The control unit may reduce the injection amount of the alkaline agent solution injected through the second injection unit when the pH of the absorption solution measured by the PH measuring instrument exceeds a reference value.

In addition, according to another embodiment of the present invention, the control unit, the sulfur dioxide concentration of the exhaust gas measured by the concentration meter exceeds the reference value or the pH of the absorption solution measured by the PH meter does not exceed the reference value In this case, the concentration of limestone in the absorbent solution may be increased.

In addition, according to another embodiment of the present invention, the inlet step of introducing the exhaust gas into the absorption tower, the first contact step of the gas-liquid contacting the exhaust gas with the alkali solution first, and the limestone (CaCO3) A second contact step of performing gas-liquid contact with the absorbent solution containing the second solution and an oxidation step of supplying an oxygen-containing gas into the absorption tank in which the alkali agent solution first contacted with the exhaust gas and the absorbent solution secondary contacted with the exhaust gas are recovered It provides a wet flue gas desulfurization method comprising a.

The first contacting step may spray the alkali solution through a second spraying unit installed in the absorption tower, and the second contacting step may spray the absorbing solution through the first spraying unit installed in the absorption tower.

In addition, the method may further include a control step of controlling the injection amount of the alkali solution injected through the second injection unit.

The method may further include a concentration measuring step of measuring sulfur dioxide concentration of the exhaust gas introduced into the absorption tower.

The control step, when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step exceeds a reference value increases the injection amount of the alkaline agent solution injected through the second injection unit, measured by the concentration measuring step When the sulfur dioxide concentration of the exhaust gas does not exceed the reference value, the injection amount of the alkaline agent solution injected through the second injection unit may be reduced.

In addition, according to another embodiment of the present invention, it may further include a PH measuring step of measuring the pH of the absorption solution in the absorption tank.

In the controlling step, when the pH of the absorbing solution measured by the PH measuring step does not exceed a reference value, the injection amount of the alkaline agent solution injected through the second spraying unit is increased, and the absorption measured by the PH measuring step When the pH of the solution exceeds the reference value, the injection amount of the alkaline agent solution injected through the second injection unit may be reduced.

Further, according to another embodiment of the present invention, the control step, the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step exceeds the reference value or the pH of the absorbing solution measured by the PH measuring step is the reference value If it does not exceed the concentration of limestone in the absorption solution can be increased.

According to the present invention, in order to absorb sulfur oxides (SOx) of the exhaust gas, the exhaust gas is brought into gas-liquid contact with the absorbing solution containing limestone (CaCO 3), and the gas-liquid contact with the alkaline agent solution separately improves the reactivity of limestone and improves the desulfurization efficiency. You can increase it.

The effects of the present invention are not limited to the above-described effects, but should be understood to include all the effects deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a schematic view showing a wet flue gas desulfurization apparatus according to a first embodiment of the present invention.
Figure 2 is a schematic diagram showing a wet flue gas desulfurization apparatus according to a second embodiment of the present invention.
Figure 3 is a schematic diagram showing a wet flue gas desulfurization apparatus according to a third embodiment of the present invention.

Hereinafter, a preferred embodiment of the wet flue gas desulfurization apparatus of the present invention will be described with reference to the accompanying drawings.

In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users or operators, and the following embodiments do not limit the scope of the present invention. It is merely illustrative of the components set forth in the claims.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification. Throughout the specification, when a part is said to "include" a certain component, it means that it may further include other components, without excluding the other components unless otherwise stated.

The wet flue gas desulfurization apparatus of the present invention is for removing sulfur oxides (mostly sulfur dioxide (SO 2)) from exhaust gases such as boilers by gas-liquid contact between absorption liquid and exhaust gas.

First, referring to FIG. 1, a wet flue gas desulfurization apparatus according to a first embodiment of the present invention will be described.

The wet flue gas desulfurization apparatus according to the first embodiment of the present invention is largely an absorption tank 100, an absorption tower 200, an exhaust gas inlet duct 210, an exhaust gas outlet duct 220, and a first injection unit 300. ), The circulation pump 320, the second injection unit 400, the alkaline agent supply unit 500, the oxygen supply pipe 600, the control unit 700 and the concentration meter 800 may be made.

Specifically, the absorption tank 100 is stored in the absorbent solution containing limestone (CaCO3) as an alkaline absorber, the absorption tank 100 may be formed to have a variety of cross-sections, such as circular or square.

The absorption tower 200 extends to the upper portion of the absorption tank 100 and may be formed integrally with the absorption tank 100.

One side of the absorption tower 200 is provided with an exhaust gas inlet duct 210 for introducing the exhaust gas, and the other side of the absorption tower 200 has an exhaust gas outlet duct 220 for discharging the purified exhaust gas. Is provided.

In the present embodiment, the inlet duct 210 is provided on the upper left side of the absorption tower 200 based on FIG. 1, and the outlet duct 220 is provided on the lower right side of the absorption tower 200. . Accordingly, the exhaust gas flowing through the inlet duct 210 flows downward in the absorption tower 200 and is discharged through the outlet duct 220.

The positions of the inlet duct 210 and the outlet duct 220 are not limited thereto, but the exhaust gas introduced through the inlet duct 210 is injected by the first injector 300 as described below. After contact with the solution and the alkali solution sprayed by the second injection unit 400 is preferably provided to be discharged through the outlet duct 220.

The absorption tower 200 is provided with a first injection unit 300 for injecting the absorption solution, the circulation pump 320 is to recover the absorption solution in the absorption tank 100 to the first injection unit 300 to feed.

In the present embodiment, the first injection unit 300 is provided below the inlet duct 210, and the exhaust gas flowing into the absorption tower 200 through the inlet duct 210 is absorbed in the absorption tower 200. Is flowed to the lower portion of the through the first injection unit 300 is discharged to the outlet duct 220.

In addition, the second injection unit 400 for spraying the alkali solution is installed in the absorption tower 200, and the alkali agent supply unit 500 is for supplying the alkali solution to the second injection unit 400. .

In this case, the second injection unit 400 may be installed in parallel with the first injection unit 300 in the absorption tower 200. In the present embodiment, the second injection unit 400 is the first injection unit. It is formed above the 1 injection part 300.

Accordingly, the exhaust gas introduced into the inlet duct 210 is primarily in contact with the alkali agent solution injected by the second injector 400, and the absorption solution injected by the first injector 300. Can be contacted secondarily. However, the present invention is not limited thereto, and the exhaust gas introduced into the inlet duct 210 may be in primary contact with the absorbing solution and may be in secondary contact with the alkali solution.

In this case, the alkaline agent may include at least one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) 2), magnesium hydroxide (Mg (OH) 2), in the present embodiment The explanation is based on the fact that the alkali agent is sodium hydroxide (NaOH).

The alkaline agent supply unit 500 includes a storage tank 520 in which the alkaline agent solution is stored and a supply pump 540 for supplying the alkaline agent solution stored in the storage tank 520 to the second injection unit 400. .

In addition, a flow rate control valve (V1) is provided on the alkali supply line for supplying the alkali solution to the second injection unit 400 from the storage tank 520 of the alkali solution supplied to the second injection unit 400 Allow the flow rate to be adjusted. Hereinafter, the flow rate control of the alkali solution supplied to the second injection unit 400 will be described in detail below.

Accordingly, the alkali agent solution injected through the second injector 400, in this embodiment, the sodium hydroxide solution and the exhaust gas introduced through the inlet duct 210 come into gas-liquid contact, and the alkali solution It absorbs sulfur dioxide present in the exhaust gas.

Specifically, the absorption tower 200 is made as follows.

(1) 2NaOH + SO 2 → Na 2 SO 3 + H 2 O

Next, the absorbing solution which is lifted by the circulation pump 320 and sprayed through the first spraying unit 300 and the exhaust gas passing through the second spraying unit 400 come into gas-liquid contact. The absorbent solution will absorb sulfur dioxide present in the exhaust gas.

Specifically, the absorption tower 200 is made as follows.

(2) SO2 + H2O → H + + HSO3-

In this case, the first injection unit 300 and the second injection unit 400 is the absorption tower 200 so that the exhaust gas passing through the absorption tower 200 does not come into contact with the absorption solution and the alkali solution does not occur. It is preferable that it is formed uniformly in all positions in the cross section of ().

Accordingly, the exhaust gas from which sulfur dioxide is removed is discharged through the outlet duct 220, and the absorbing solution and the alkaline agent solution absorbing the sulfur dioxide fall back into the absorption tank 100.

Hereinafter, after the alkali agent solution absorbing sulfur dioxide falls into the absorption tank 100 as described above, the absorbing solution will be referred to as an absorbent solution.

At this time, water (mist) is contained in the exhaust gas flowing through the first injection unit 300 and the second injection unit 400 toward the outlet duct 220, to absorb and remove the exit duct The moisture eliminator 230 may be installed at 220.

As described above, in order to absorb sulfur oxides (SOx) of the exhaust gas, the exhaust gas is brought into gas-liquid contact with the absorption solution containing limestone (CaCO 3), and at the same time, the gas-liquid contact with the alkali agent solution improves the reactivity of limestone and increases the desulfurization efficiency. You can.

The absorption tank 100 is provided with an oxygen supply pipe 600 for supplying an oxygen-containing gas, in this embodiment air.

As air is supplied into the absorption solution of the absorption tank 100 by the oxygen supply pipe 600, the oxidation reaction of sulfite is performed in the absorption tank 100, thereby gypsum (CaSO 4 .2H 2 O) as a by-product. Is formed. The gypsum thus formed is suspended in the absorbent solution and sinks to the lower side of the absorbent tank 100.

Hereinafter, in the absorption tank 100, the following reactions are made.

(3) Na2SO3 + 1/2 O2 → Na2SO4 → 2Na + + SO42-

    2Na + + SO42- + CaCO3 + 2H2O → CaSO4, 2H2O + Na2CO3

(4) H + + HSO3- + 1/2 O2 → 2H + + SO42-

    2H + + SO42- + CaCO3 + H2O → CaSO4, 2H2O + CO2

At this time, the oxidation reaction of the sulfite may be naturally oxidized in the absorption tower 200 or the absorption tank 100 by the oxygen contained in the exhaust gas.

It may further include a stirrer 120 for stirring the absorbing solution in the absorption tank 100, the air supplied through the oxygen supply pipe 600 is fine as the rotational flow is formed in the absorption tank 100 It can be divided so that the contact area and time between the air and the absorbent solution can be increased, and the oxidation efficiency can be improved.

In addition, according to another embodiment of the present invention, the oxygen supply pipe is arranged in a plurality of spaced apart from each other along the circumferential direction of the absorption tank 100, so as to be inclined in the same direction along the circumferential direction of the absorption tank 100. It may be arranged, so that the absorption of the absorption solution may be made by the air supplied through the plurality of oxygen supply pipe without a separate stirrer.

The by-product discharge portion 900 for discharging the gypsum generated as described above is provided at the lower portion of the absorption tank 100. The by-product discharge section 900 includes a discharge pump 920 and a solid-liquid separator 940, the absorbing solution containing gypsum is recovered by the discharge pump 920, the solid-liquid separator 940 It can be introduced into, so that the absorbed sulfur dioxide can be completely removed by separating the solid material gypsum and filtrate.

Furthermore, the filtrate may be transferred to a filtration tank (not shown), mixed with limestone, and then returned to the absorption tank 100.

In order to adjust the flow rate of the alkali agent solution supplied to the second injection unit 400, that is, to adjust the injection amount of the alkali agent solution injected through the second injection unit 400, the present invention is the control unit 700 and the concentration Meter 800.

The concentration measuring unit 800 is for measuring the sulfur dioxide concentration of the exhaust gas flowing into the inlet duct 210, the control unit 700 according to the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring unit 800 The injection amount of the alkaline solution injected through the second injection unit 400 may be controlled.

At this time, the flow control valve (V1) is made of an electric valve to adjust the flow rate by receiving an electrical signal to adjust the opening, the control unit 700 is an electrical signal to adjust the opening degree of the flow control valve (V1). can send.

Specifically, the control unit 700, when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring instrument 800 exceeds a reference value, the injection amount of the alkali solution injected through the second injection unit 400 Can be increased. That is, the controller 700 may increase the flow rate of the alkaline agent solution supplied to the second injection unit 400 by sending an electrical signal to open the flow control valve V1.

In addition, when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring instrument 800 does not exceed a reference value, the controller 700 decreases the injection amount of the alkaline agent solution injected through the second injection unit 400. You can. That is, the control unit 700 may reduce the flow rate of the alkaline agent solution supplied to the second injection unit 400 by sending an electrical signal to close the flow control valve (V1).

Therefore, by adjusting the injection amount of the alkali agent solution injected through the second injection unit 400 in accordance with the sulfur dioxide concentration of the exhaust gas, the absorption of sulfur dioxide contained in the exhaust gas can be made efficiently, and the sulfur dioxide of the exhaust gas. Even when the concentration is increased, the reactivity of limestone can be prevented from being lowered. Moreover, the operating cost can be reduced by adjusting the injection amount of the alkali solution.

Next, a wet flue gas desulfurization apparatus according to a second embodiment of the present invention will be described with reference to FIG. 2.

The wet flue gas desulfurization apparatus according to the second embodiment of the present invention is largely an absorption tank 100, an absorption tower 200, an exhaust gas inlet duct 210, an exhaust gas outlet duct 220, and a first injection unit 300. ), The circulation pump 320, the second injection unit 400, the alkaline agent supply unit 500, the oxygen supply pipe 600, the control unit 2700 and the PH measuring device 2800 may be made.

At this time, the control unit 2700 and the PH measuring device for adjusting the flow rate of the alkali agent solution supplied to the second injection unit 400, that is, to adjust the injection amount of the alkali agent solution injected through the second injection unit 400 Only 2800 is different from the first embodiment, and the rest of the configuration is the same, and thus different parts will be mainly described.

The PH measuring device 2800 is for measuring the pH of the absorbing solution in the absorption tank 100, the control unit 2700 is the second minute in accordance with the pH of the absorbing solution measured by the PH measuring device 2800 It is possible to control the injection amount of the alkaline solution is injected through the sand 400.

Similarly, the flow control valve V1 is an electric valve to adjust the flow rate by receiving an electrical signal to adjust the opening degree, the control unit 2700 is an electrical signal to adjust the opening degree of the flow control valve (V1). can send.

Specifically, the control unit 2700, when the PH of the absorbing solution measured by the PH measuring device 2800 does not exceed the reference value increases the injection amount of the alkaline solution injected through the second injection unit 400 You can. That is, the control unit 2700 may increase the flow rate of the alkaline agent solution supplied to the second injection unit 400 by sending an electrical signal to open the flow control valve V1.

In addition, when the pH of the absorbing solution measured by the PH measuring instrument 2800 exceeds a reference value, the control unit 2700 may reduce the injection amount of the alkaline agent solution injected through the second injection unit 400. Can be. That is, the controller 2700 may reduce the flow rate of the alkaline agent solution supplied to the second injection unit 400 by sending an electric signal to close the flow control valve V1.

Therefore, by adjusting the injection amount of the alkali agent solution injected through the second injection unit 400 in accordance with the pH of the absorption solution, the absorption of sulfur dioxide contained in the exhaust gas can be made efficiently, the sulfur dioxide concentration of the exhaust gas Even if becomes high, the reactivity of limestone can be prevented from falling. Moreover, the operating cost can be reduced by adjusting the injection amount of the alkali solution.

Finally, referring to FIG. 3, the wet flue gas desulfurization apparatus according to the third embodiment of the present invention will be described.

The wet flue gas desulfurization apparatus according to the third embodiment of the present invention is the same as the wet flue gas desulfurization apparatus according to the first embodiment, and further includes a limestone tank 140 and a flow control valve V2, and thus different parts are provided. Focus on explanation.

The limestone tank 140 stores an absorption solution including limestone (CaCO 3), and is for supplying limestone into the absorption tank 100.

A flow rate control valve V2 is installed on the absorption solution supply line through which the absorption solution is supplied from the limestone tank 140 to the absorption tank 100. The absorption tank 100 is provided by the flow control valve V2. Supply amount of the absorption solution supplied to the can be adjusted.

At this time, the flow rate control valve (V2) is made of an electric valve can receive the electrical signal to adjust the flow rate by adjusting the opening degree.

Accordingly, the controller 700 controls and controls the opening degree of the flow rate control valve V1 to control the flow rate of the alkaline agent solution supplied to the second injection part 400, and the limestone tank 140. In order to control the opening degree of the flow control valve (V2) to control the amount of the absorption solution supplied to the absorption tank 100 in the control, for this purpose it can send an electrical signal to the flow control valve (V1, V2) have.

Specifically, the control unit 700 may increase the concentration of limestone in the absorption solution when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring instrument 800 exceeds the reference value. That is, the control unit 700 may increase the flow rate of the absorption solution supplied to the absorption tank 100 by sending an electrical signal to open the flow rate control valve (V2).

Therefore, the same effect as in the first embodiment may be obtained by adjusting the injection amount of the alkali agent solution injected through the second injection unit 400 according to the sulfur dioxide concentration of the exhaust gas, and further, from the limestone tank 140. By adjusting the supply amount of the absorption solution supplied to the absorption tank 100, it is possible to further increase the reactivity and desulfurization efficiency of limestone.

However, the present invention is not limited thereto, and the limestone tank 140 and the flow control valve V2 are applied to the second embodiment, so that the controller 2700 measures the pH of the absorbing solution measured by the PH meter 2800. Does not exceed the reference value to increase the concentration of limestone in the absorption solution, or the injection amount of the solution sprayed through the first injection unit 300 and the second injection unit 400 is not controlled and the concentration meter ( 800 or the amount of absorption liquid supplied from the limestone tank 140 to the absorption tank 100 may be adjusted according to the sulfur dioxide concentration of the exhaust gas measured by the PH measuring unit 2800 or the pH of the absorption liquid.

Hereinafter, referring to the wet flue gas desulfurization method of the present invention, the wet flue gas desulfurization method of the present invention includes an inflow step of introducing the exhaust gas into the absorption tower 200 and a primary contact of the exhaust gas to the gas-liquid contact with the alkali solution first. And a second contact step of gas-liquid contacting the exhaust gas with an absorbing solution containing limestone (CaCO 3) in a second step; and recovering the alkaline agent solution in primary contact with the exhaust gas and the absorbing solution in secondary contact with the exhaust gas. And an oxidation step of supplying an oxygen-containing gas into the absorption tank 100.

In detail, as described in the embodiment of the wet flue gas desulfurization apparatus, exhaust gas may be introduced into the absorption tower 200 through the inlet duct 210.

In addition, the first contacting step is to spray the alkali solution through the second injection unit 400 installed in the absorption tower 200, the second contacting step is a first installed in the absorption tower 200 The absorption solution may be injected through the injection unit 300.

That is, the alkali solution may be supplied from the storage tank 520 to the second injection unit 400 by the supply pump 540 and injected therethrough, and the absorption solution may be injected from the absorption tank 100. It is supplied to the first injection unit 300 by the circulation pump 320 can be injected through it.

In the oxidation step, oxidation of sulfite may occur as the oxygen-containing gas (air) is supplied into the absorption tank 100 by the oxygen supply pipe 600.

In addition, the method may further include a control step of controlling the injection amount of the alkali solution injected through the second injection unit 400.

First, referring to the wet flue gas desulfurization apparatus according to the first embodiment, it may further include a concentration measuring step of measuring the sulfur dioxide concentration of the exhaust gas flowing into the absorption tower 200, the control step The injection amount of the alkali agent solution injected through the second injection unit 400 may be controlled according to the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step.

Specifically, the control step, when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step exceeds the reference value increases the injection amount of the alkaline agent solution injected through the second injection unit 400, When the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step does not exceed the reference value, the injection amount of the alkaline agent solution injected through the second injection unit 400 may be reduced.

As described in the first embodiment, the controller 700 may control the opening degree of the flow rate control valve V1 according to the sulfur dioxide concentration of the exhaust gas measured by the concentration meter 800. .

Next, referring to the wet flue gas desulfurization apparatus according to the second embodiment, it may further include a PH measuring step of measuring the pH of the absorption solution in the absorption tank 100, the control step is the PH According to the pH of the absorbing solution measured by the measuring step, it is possible to control the injection amount of the alkali solution sprayed through the second injection unit 400.

Specifically, the control step, when the PH of the absorbing solution measured by the PH measuring step does not exceed the reference value increases the injection amount of the alkaline agent solution injected through the second injection unit, by the PH measuring step When the measured pH of the absorbent solution exceeds a reference value, the injection amount of the alkaline agent solution injected through the second injection unit may be reduced.

As described in the second embodiment, the controller 2700 may be controlled by controlling the opening degree of the flow regulating valve V1 according to the pH of the absorbing solution measured by the PH measuring instrument 2800.

Finally, when the wet flue gas desulfurization apparatus according to the third embodiment is described as a reference, the control step includes the concentration of limestone in the absorption solution when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step exceeds a reference value. Can be increased.

As described in the third embodiment, the controller 700 controls the opening degree of the flow rate control valve V2 according to the sulfur dioxide concentration of the exhaust gas measured by the concentration meter 800 to control the limestone tank. It may be made by adjusting the supply amount of the absorption solution supplied to the absorption tank 100 in 140.

The present invention is not limited to the above-described specific embodiments and descriptions, and various modifications can be made by those skilled in the art without departing from the gist of the present invention claimed in the claims. Such variations are within the protection scope of the present invention.

100: absorption tank 120: stirrer
140: limestone tank 200: absorption tower
210: exhaust gas inlet duct 220: exhaust gas outlet duct
230: moisture dehumidifier 300: first injection unit
320: circulation pump 400: second injection portion
500: alkali supply unit 520: storage tank
540: supply pump 600: oxygen supply pipe
700: control unit 800: concentration meter
900: by-product discharge unit 920: discharge pump
940: solid-liquid separator
V1, V2: flow control valve
2700 control unit 2800 PH meter

Claims (22)

Absorption tank in which the absorption solution containing limestone (CaCO3) is stored;
An absorption tower extending to an upper portion of the absorption tank;
An exhaust gas inlet duct provided at one side of the absorption tower;
An exhaust gas outlet duct provided on the other side of the absorption tower;
A first injection unit installed in the absorption tower to inject the absorption solution;
A circulation pump for supplying the absorption liquid in the absorption tank to the first injection portion;
A second injector installed in the absorption tower to inject an alkaline solution;
An alkaline agent supply unit supplying an alkaline agent solution to the second injection unit; And
An oxygen supply pipe for supplying an oxygen-containing gas to the absorption tank;
Including, wet flue gas desulfurization apparatus. The method of claim 1,
The exhaust gas introduced into the inlet duct is primarily in contact with the alkali agent solution injected by the second injector, and secondly in contact with the absorption solution injected by the first injector. The method of claim 1,
The alkaline agent comprises at least one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) 2), magnesium hydroxide (Mg (OH) 2), wet flue gas desulfurization apparatus. The method of claim 1,
The alkaline agent supply unit,
A storage tank in which the alkaline solution is stored; And
A supply pump for supplying an alkali solution stored in the storage tank to the second injection unit;
Including, wet flue gas desulfurization apparatus. The method of claim 4, wherein
The flue gas desulfurization apparatus is provided with a flow rate control valve on the alkaline agent supply line to which the alkaline agent solution is supplied from the storage tank to the second injection portion. The method of claim 5,
A control unit for controlling the injection amount of the alkali solution injected through the second injection unit;
Further comprising, a wet flue gas desulfurization apparatus. The method of claim 6,
A concentration meter for measuring sulfur dioxide concentration of the exhaust gas flowing into the inlet duct;
Further comprising, a wet flue gas desulfurization apparatus. The method of claim 7, wherein
And the control unit increases the injection amount of the alkaline agent solution injected through the second injection unit when the sulfur dioxide concentration of the exhaust gas measured by the concentration meter exceeds a reference value. The method of claim 7, wherein
The control unit, wet flue gas desulfurization apparatus to reduce the injection amount of the alkali agent solution injected through the second injection unit when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring instrument does not exceed a reference value. The method of claim 6,
A pH meter for measuring the pH of the absorption solution in the absorption tank;
Further comprising, a wet flue gas desulfurization apparatus. The method of claim 10,
The control unit, when the pH of the absorbing solution measured by the PH measuring instrument does not exceed the reference value, the wet flue gas desulfurization apparatus to increase the injection amount of the alkali agent solution injected through the second injection unit. The method of claim 10,
The control unit, the wet flue gas desulfurization apparatus to reduce the injection amount of the alkali agent solution injected through the second injection unit when the pH of the absorption solution measured by the PH measuring instrument exceeds the reference value. The method of claim 6,
The flow regulating valve is an electric valve, wet flue gas desulfurization apparatus. The method according to claim 7 or 10,
The control unit increases the concentration of limestone in the absorbent solution when the sulfur dioxide concentration of the exhaust gas measured by the concentration meter exceeds a reference value or when the pH of the absorbent solution measured by the PH meter does not exceed the reference value. Wet flue gas desulfurization apparatus. An inflow step of introducing exhaust gas into the absorption tower;
A first contact step of gas-liquid contacting the exhaust gas with an alkali solution first;
A second contact step of gas-liquid contacting the exhaust gas with an absorption solution containing limestone (CaCO 3) in a second manner; And
An oxidation step of supplying an oxygen-containing gas into an absorption tank in which an alkaline solution in primary contact with the exhaust gas and an absorption solution in secondary contact with the exhaust gas are recovered;
Wet flue gas desulfurization method comprising a. The method of claim 15,
The first contacting step sprays the alkali solution through a second spraying unit installed in the absorption tower, and the second contacting step sprays the absorbing solution through the first spraying unit installed in the absorption tower. Desulfurization method. The method of claim 16,
A control step of controlling the injection amount of the alkali agent solution injected through the second injection unit;
Further comprising, wet flue gas desulfurization method. The method of claim 17,
A concentration measuring step of measuring sulfur dioxide concentration of exhaust gas flowing into the absorption tower;
Further comprising, wet flue gas desulfurization method. The method of claim 18,
The control step, when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step exceeds a reference value increases the injection amount of the alkaline agent solution injected through the second injection unit, measured by the concentration measuring step When the sulfur dioxide concentration of the exhaust gas does not exceed the reference value, the wet flue gas desulfurization method for reducing the injection amount of the alkaline agent solution injected through the second injection unit. The method of claim 17,
PH measuring step of measuring the pH of the absorption solution in the absorption tank;
Further comprising, wet flue gas desulfurization method. The method of claim 20,
In the controlling step, when the pH of the absorbing solution measured by the PH measuring step does not exceed a reference value, the injection amount of the alkaline agent solution injected through the second spraying unit is increased, and the absorption measured by the PH measuring step And when the pH of the solution exceeds the reference value, reducing the injection amount of the alkali solution injected through the second injection unit. The method of claim 18 or 20,
The controlling step may include the case of limestone in the absorbent solution when the sulfur dioxide concentration of the exhaust gas measured by the concentration measuring step exceeds the reference value or when the pH of the absorbing solution measured by the PH measuring step does not exceed the reference value. Wet flue gas desulfurization method to increase the concentration.

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