JP2004074058A - Apparatus for desulfurizing wet flue gas and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for desulfurizing wet flue gas and a method for the same in which oxidation air is finely distributed without using an agitator, in which ability for oxidizing sulfite in alkali absorbing solution absorbing acidic gas in flue gas is heightened, and of which cost is reduced. <P>SOLUTION: The alkali absorbing solution absorbing the acidic gas in the flue gas by spraying in an absorption tower is recovered in a liquid recovery part 14 provided in a position higher than the liquid level of a circulation tank in the absorption tower main body 1. Then, this recovery liquid absorbing the acidic gas is distributed in the absorbing solution of a circulation tank 6 with use of a two fluid nozzle 17 connected with an oxidation air supply-pipe 8 supplying the oxidation air to a recovery liquid supply-pipe 16 and the absorbing solution in the circulation tank 6. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wet flue gas desulfurization device for removing sulfur dioxide (SO ₂ ) in exhaust gas discharged from a combustion device such as a power boiler, and more particularly to a method for supplying oxidized air.
[0002]
[Prior art]
FIG. 12 shows a schematic side view of an absorption tower constituting a desulfurization device as a known example of a wet flue gas desulfurization device employing a conventional spray method. This wet flue gas desulfurization apparatus mainly includes an absorption tower main body 1, an inlet duct 2, an outlet duct 3, an absorption liquid circulation pump 4, a circulation tank 6, a stirrer 7, an air supply pipe 8, a mist eliminator 9, and an absorption liquid discharge pipe 10. , A circulation pipe 11, a spray header 12, a spray nozzle 13, and the like.
[0003]
The exhaust gas discharged from the boiler is introduced into the absorption tower main body 1 from the inlet duct 2 and discharged from the outlet duct 3 provided at the top of the tower. The absorption liquid 5 containing calcium carbonate sent from the absorption liquid circulation pump 4 is jetted from the spray nozzle 13, and gas-liquid contact between the absorption liquid 5 and exhaust gas is performed. At this time, the absorbing liquid 5 absorbs SO ₂ in the exhaust gas and generates sulfurous acid (Ca (HSO ₃ ) ₂ ). The absorbent 5 that has fallen into the circulation tank 6 descends in the tank, is sucked into the circulation pump 4, and is again ejected from the spray nozzle 13.
[0004]
During this time, Ca (HSO ₃ ) ₂ in the absorbing solution is oxidized by oxygen in the air 15 supplied from the air supply pipe 8 to generate calcium sulfate (gypsum). Since the air 15 is supplied from behind the oxidizing stirrer 7, the air 15 is miniaturized by rotation of the stirrer blades. For this reason, the gas-liquid contact area increases, and the oxidation efficiency is improved.
[0005]
[Problems to be solved by the invention]
In the above-mentioned conventional technology, when the supply amount of the oxidizing air is increased, the number of the oxidizing agitators 7 must be increased. This is because the amount of oxidizing air that can be supplied per stirrer is limited. Further, if air exceeding the limit is supplied to the stirrer 7, the air is not fined by the stirrer 7.
[0006]
An object of the present invention is to reduce the size of oxidizing air without using a stirrer, to enhance the oxidizing performance of sulfite in an alkali absorbing solution that has absorbed acid gas in exhaust gas, and to provide a low-cost wet flue gas desulfurization apparatus and method. It is to provide.
[0007]
[Means for Solving the Problems]
In the present invention described in the following (1) and (2), an air supply method that replaces the conventional oxidation stirrer 7 shown in FIG. The absorbing liquid falling in the absorption tower is collected at a position higher than the liquid level in the circulation tank, and the collected liquid is poured into the circulation tank via the two-fluid nozzle. At this time, by supplying oxidizing air to the two-fluid nozzle at the same time, micronized bubbles can be supplied to the circulation tank, and the sulfite in the alkali absorbing solution that has absorbed the acidic gas in the exhaust gas at low cost. Oxidation performance can be increased.
[0008]
The present invention comprises (1) a wet flue gas desulfurization apparatus and (2) a wet flue gas desulfurization method having the following configurations.
(1) A flue gas discharged from a combustion device such as a boiler is introduced from an inlet duct, and a flue gas flow path discharged from an outlet duct is provided. In a wet flue gas desulfurization device equipped with an absorption tower for treating sulfur oxides in exhaust gas and a circulation tank for storing the absorbing liquid falling from the absorption tower, the exhaust gas and gas-liquid This is a wet flue gas desulfurization apparatus provided with one or more two-fluid nozzles in the circulation tank for supplying the absorption liquid and the oxidizing air to the circulation tank while mixing them.
[0009]
A liquid recovery section is provided at a position higher than the liquid level in the circulation tank in the absorption tower, and a recovery liquid supply pipe for supplying the recovery liquid from the liquid recovery section into the absorption liquid in the circulation tank and an oxidizing air in the circulation tank. A configuration in which the oxidizing air supply pipe for supplying the liquid is connected to the two-fluid nozzle may be adopted.
[0010]
Also, a configuration in which one or more two-fluid nozzles are arranged on the bottom of the circulation tank or the opposing side wall, or the two-fluid ejection direction of the one or more two-fluid nozzles is horizontal or substantially horizontal or lower than the horizontal. , The bubbles discharged from the two-fluid nozzle may be uniformly dispersed in the circulation tank, or the gypsum may be prevented from being deposited on the bottom surface of the circulation tank.
[0011]
In addition, vanes are provided at the discharge ports of the one or more two-fluid nozzles so that the gas-liquid mixed fluid is discharged into the absorbing liquid as a swirling flow to promote finer oxidizing air and oxidize the absorbing liquid. Efficiency may be increased.
[0012]
Further, the liquid recovery unit may be provided in the entire horizontal or substantially horizontal cross section of the lower part of the absorption tower in order to collect all of the absorption liquid after being brought into gas-liquid contact with the exhaust gas in the absorption tower. good.
[0013]
Further, a pump for liquid circulation may be arranged in a recovery liquid supply pipe for supplying the recovery liquid from the liquid recovery section to one or more two-fluid nozzles.
[0014]
A blow-off pump for supplying an absorbing liquid or air for discharging solids in the recovery liquid supply pipe and the oxidizing air supply pipe into the circulation tank may be provided in a piping system connected to the supply pipe.
[0015]
(2) It has an exhaust gas channel that introduces exhaust gas discharged from a combustion device such as a boiler from an inlet duct and discharges it from an outlet duct. In the wet flue gas desulfurization method using an absorption tower for treating sulfur oxides in the exhaust gas and a circulation tank for storing the absorption liquid sprayed in the absorption tower, the gas-liquid contact with the exhaust gas in the absorption tower This is a wet flue gas desulfurization method in which the oxidized air is refined while the absorbent after mixing with the oxidized air is mixed with one or more two-fluid nozzles and supplied to the absorbent in the circulation tank.
[0016]
A method of supplying the recovered liquid from the liquid recovery unit provided at a position higher than the liquid level of the circulation tank in the absorption tower to one or more two-fluid nozzles may be adopted.
[0017]
In addition, bubbles discharged from one or more two-fluid nozzles are uniformly dispersed in the circulation tank.
[0018]
Further, the gas-liquid mixed fluid discharged by one or more two-fluid nozzles is jetted obliquely downward from the bottom surface or side surface of the circulation tank toward the horizontal direction, substantially horizontal direction, or the bottom surface.
[0019]
By discharging the gas-liquid mixed fluid into the absorbing liquid while swirling by one or more two-fluid nozzles, the oxidizing air can be made finer and dispersed in the absorbing liquid to increase the oxidizing efficiency of the absorbing liquid.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic side view of an absorption tower constituting a desulfurization apparatus according to an embodiment of the present invention. This wet flue gas desulfurization apparatus mainly includes an absorption tower main body 1, an inlet duct 2, an outlet duct 3, an absorption liquid circulation pump 4, a circulation tank 6, an air supply pipe 8, a mist eliminator 9, an absorption liquid discharge pipe 10, a circulation pipe. 11, a spray header 12, a spray nozzle 13, a liquid recovery unit 14, a liquid recovery supply pipe 16, a two-fluid nozzle 17, and the like.
[0021]
Exhaust gas discharged from a combustion device (not shown) such as a boiler is introduced into the absorption tower main body 1 from an inlet duct 2 and discharged from an outlet duct 3 provided at the top of the tower. The absorption liquid 5 containing calcium carbonate sent from the absorption liquid circulation pump 4 is jetted from the spray nozzle 13, and gas-liquid contact between the absorption liquid 5 and exhaust gas is performed. At this time, the absorbing liquid 5 absorbs SO ₂ in the exhaust gas and generates sulfurous acid (Ca (HSO ₃ ) ₂ ). The absorbent 5 that has fallen into the circulation tank 6 descends in the circulation tank 6, is sucked into the circulation pump 4, and is ejected from the spray nozzle 13 again.
[0022]
The feature of this embodiment is that the liquid recovery unit 14 is provided on the side wall of the absorption tower of the absorption tower main body 1 and the liquid recovered by the liquid recovery unit 14 is supplied to the two-fluid nozzle 17 provided on the bottom wall of the circulation tank 6. At this time, an air supply pipe 8 is also provided on the bottom wall of the circulation tank 6, and the oxidizing air supplied from the air supply pipe 8 flows into the two-fluid nozzle 17 together with the liquid recovered by the liquid recovery part 14, It is supplied from the nozzle 17 into the circulation tank 6.
[0023]
In the embodiment shown in FIG. 1, the absorbing liquid 5 injected from the spray nozzle 13 absorbs SO ₂ in the exhaust gas in the absorption tower. The absorbed SO ₂ reacts with CaCO ₃ in the absorbing solution to become sulfurous acid (Ca (HSO ₃ ) ₂ ). The absorbing liquid falls into the circulation tank 6 and the liquid collecting section 14. The absorbent dropped on the liquid surface of the circulation tank 6 descends in the tank and is oxidized by the oxidizing air 15 supplied from the air supply pipe 8 in the absorbent before being sucked into the circulation pump 4, and calcium sulfate It becomes.
[0024]
Therefore, it is important how to oxidize Ca (HSO ₃ ) ₂ efficiently in the circulation tank 6. In the prior art shown in FIG. 12, the impeller of the stirrer 7 is disposed in front of the air supply pipe 8, and the rotation of the impeller turns the oxidized air 15 into microbubbles. By making the air finer, the contact area between the absorbing liquid and the bubbles was increased, and the oxidation efficiency was improved. However, for example, when treating a high SO ₂ concentration exhaust gas, the amount of Ca (HSO ₃ ) ₂ in the absorbing solution increases, and the amount of air supplied accordingly increases. Since the amount of oxidizing air that can be supplied to one stirrer 7 is limited, the number of stirrers 7 must be increased.
[0025]
On the other hand, in the embodiment of the present invention shown in FIG. 1, a stirrer 7 for finely oxidizing air as shown in FIG. 12 is not provided. The absorbing liquid that has dropped into the liquid recovery unit 14 flows through the liquid recovery supply pipe 16 into the two-fluid nozzle 17. At this time, since the pressure corresponding to the height from the liquid surface of the circulation tank 6 to the liquid recovery section is applied to the liquid flowing into the two-fluid nozzle 17, a large amount of high-pressure recovered liquid flows into the two-fluid nozzle 17.
[0026]
On the other hand, air is supplied to the two-fluid nozzle 17 from the oxidizing air supply pipe 8. The inside of the two-fluid nozzle 17 has a cross-sectional structure shown in FIG. 2. The high-pressure recovery liquid and the air are mixed, and fine bubbles are discharged from the tip of the nozzle 17. However, the structure of the two-fluid nozzle 17 does not necessarily need to be the structure shown in FIG. 2, and may be any structure as long as the liquid and the oxidizing air are mixed.
[0027]
As described above, instead of the conventional oxidizing stirrer 7, the liquid recovery unit 14 is installed on the side wall of the absorption tower main body 1, and the two-fluid nozzle 17 is installed on the wall surface (not limited to the bottom wall) of the circulation tank 6. The air supplied into the absorption liquid in the circulation tank 6 becomes fine bubbles only by performing the above operation, and Ca (HSO ₃ ) ₂ can be efficiently oxidized by increasing the gas-liquid contact.
[0028]
As shown in FIG. 1, collecting the absorbing liquid falling into the circulation tank 6 and supplying the oxidizing air into the pipe through which the collected liquid flows into the circulation tank 6 is disclosed in Japanese Patent Application Laid-Open No. 8-257347. However, the present invention differs from these conventional inventions in that the air is made finer by using a two-fluid nozzle 17.
[0029]
If only the oxidizing air is supplied into the pipe into which the absorbing liquid flows into the circulation tank 6, the bubbles are not uniformly reduced, and the oxidation efficiency is poor. In the prior art, as shown in FIG. 13, there is a case where a supply hole 21 is provided in an air supply pipe 8 provided at the bottom of the circulation tank 6 to supply the air 15 into the absorbing liquid. Is hard to get. By using the two-fluid nozzle 17 as in the present invention, the oxidizing air must be actively miniaturized.
[0030]
In the present invention, the liquid recovered by the liquid recovery unit 14 is injected together with the oxidizing air 15 from the two-fluid nozzle 17. The liquid recovered by the liquid recovery unit 14 is a liquid immediately after absorbing SO ₂ , and has a high Ca (HSO ₃ ) ₂ concentration. The liquid recovered by the liquid recovery unit 14 is injected into the absorbing liquid while being mixed with the oxidized air that has been miniaturized by the two-fluid nozzle 17. Since the absorbent having a high Ca (HSO ₃ ) ₂ concentration and the oxidizing air are in efficient contact with each other, the oxidation efficiency is high.
[0031]
The two-fluid nozzle 17 is disposed on the entire bottom surface of the circulation tank 6. Since the oxidizing air 15 is supplied from these two-fluid nozzles 17, the oxidizing air is uniformly supplied into the circulation tank 6. However, when a large amount of air bubbles are contained in the liquid sucked into the circulation pump 4, the two-fluid nozzle 17 may not be disposed near the circulation pump 4 in order to prevent a decrease in the amount of the circulation liquid and damage to the pump. is there.
[0032]
In the prior art shown in FIG. 12, the oxidizing stirrer 7 must be installed on the side wall of the circulation tank 6. For this reason, the supplied oxidizing air is also supplied from the vicinity of the side wall of the circulation tank 6, and it is difficult to uniformly disperse the oxidation air throughout the circulation tank 6.
[0033]
Further, in the present invention, the air (fine bubbles) supplied to the two-fluid nozzle 17 rises inside the circulation tank 6 immediately after being injected from the two-fluid nozzle 17. As the bubbles rise, the liquid flow also rises. On the other hand, the absorbing liquid sprayed from the spray 13 always falls on the liquid surface of the circulation tank 6. The absorbing liquid that has dropped onto the liquid surface of the circulation tank 6 descends inside the circulation tank 6. This downward flow and the upward flow due to the bubbles ejected from the two-fluid nozzle 17 collide in the absorption liquid in the circulation tank 6 to promote liquid mixing and gas-liquid contact. Therefore, the oxidation efficiency is further improved.
[0034]
FIG. 3 is a diagram comparing the oxidizing performance of the absorbent in the circulation tank 6 to which the present invention is applied with the conventional technology shown in FIG. FIG. 12 shows respective values when the present invention is applied when the oxidation rate and the air amount of the circulation tank 6 to which the conventional technique shown in FIG. 12 is applied are set to 1. The amount of oxidizing air to be supplied and the concentration of sulfurous acid in the absorbing liquid falling on the tank liquid surface were kept constant, and a part of the falling absorbing liquid was supplied to the two-fluid nozzle 17 in the circulation tank 6 to which the present invention was applied. From FIG. 3, it can be seen that even if the same amount of air is supplied, the oxidation rate of the circulation tank 6 to which the present invention is applied is improved about 1.2 times as compared with the conventional art.
[0035]
In the embodiment shown in FIG. 4, the absorbing liquid jetted from the spray nozzle of the absorption tower main body 1 is temporarily stored in the lower part of the tower main body 1, and all of the absorbing liquid is supplied to the two-fluid nozzle 17 by the recovery liquid supply pipe 16. This is different from the embodiment shown in FIG. In general, in the two-fluid nozzle 17, when the amount of liquid supplied for miniaturizing a gas increases, the miniaturization of bubbles is promoted. By supplying all of the absorbing liquid falling into the circulation tank 6 to the two-fluid nozzle 17, it is possible to make the air finer than in the embodiment shown in FIG. 1 and improve the oxidation rate. The absorbing liquid 5 sprayed from the spray nozzle 13 is collected in a collecting liquid supply pipe 16 at a lower part of the absorption tower main body 1, and flows into the circulation tank 6 through the collecting liquid supply pipe 16. At this time, fine bubbles are supplied by the two-fluid nozzle 17. The absorbent flowing into the circulation tank 6 from the two-fluid nozzle 17 descends in the tank. On the other hand, the fine bubbles simultaneously supplied to the two-fluid nozzle 17 begin to rise after having once descended in the circulation tank 6 with the downward flow. Air bubbles are reduced near the bottom surface of the circulation tank 6, and the air bubbles sucked into the circulation pump 4 are also reduced. For this reason, it is also possible to prevent a decrease in the circulating flow rate of the pump 4 due to air bubbles.
[0036]
The embodiment shown in FIG. 5 is different from the embodiments shown in FIGS. 1 to 4 in that when the diameter of the circulation tank 6 is small, a two-fluid nozzle 17 is installed on the side of the circulation tank 6 and oxidized air is supplied from the side of the tank 6. Is different from the embodiment shown in FIG. When the diameter of the circulation tank 6 is small, even when the two-fluid nozzle 17 is provided on the side wall of the tank, the bubbles can be uniformly dispersed in the tank 6 by the discharge flow from the nozzle 17.
[0037]
The embodiment shown in FIG. 6 is different from the embodiment shown in FIGS. 1 to 5 in that the two-fluid nozzle 17 is installed horizontally at the bottom of the circulation tank 6. By disposing a two-fluid nozzle 17 at the bottom of the circulation tank 6 and directing the longitudinal direction of the nozzle 17 in the horizontal direction, the gypsum at the bottom of the circulation tank 6 is discharged by the discharge flow jetted horizontally from the nozzle 17. It is possible to prevent deposition.
[0038]
Further, as shown in FIG. 7, the same effect can be obtained by directing the two-fluid nozzle 17 installed on the side of the circulation tank 6 downward and injecting the discharge flow from the nozzle 17 toward the bottom of the circulation tank 16. It is possible.
[0039]
The embodiment shown in FIG. 8 differs from the embodiment shown in FIGS. 1 to 6 in that a supply pump 18 is provided in a pipe 16 for supplying a liquid from a liquid recovery unit 14 to a two-fluid nozzle 17. The liquid supplied to the two-fluid nozzle 17 must be at a high pressure. The pressure of the difference between the liquid recovery unit 14 and the liquid level of the circulation tank 6 is the pressure of the liquid supplied to the two-fluid nozzle 17. When the absorption tower is low and the liquid recovery unit 14 cannot be installed at a high position of the absorption tower, a supply pump 18 is installed in a pipe 16 that supplies the recovered liquid from the liquid recovery unit 14 to the two-fluid nozzle 17, and the necessary pressure is reduced. Obtainable.
[0040]
The embodiment shown in FIG. 9 is different from the embodiments shown in FIGS. 1 to 8 in that a blow-off pump 19 is provided in a pipe 16 for supplying a recovery liquid from a liquid recovery unit 14 to a two-fluid nozzle 17. When the gypsum concentration in the absorbent 5 in the circulation tank 6 is high and the apparatus is stopped, such as during inspection, gypsum may accumulate in the nozzle 17. When the apparatus is started again, the nozzle 17 is blocked by the deposited gypsum, and oxidizing air cannot be supplied.
[0041]
In the embodiment shown in FIG. 9, the blow-off pump 19 is installed on the absorption liquid supply pipe 22 for supplying the absorption liquid to the pipe 16 and the air supply pipe 8 from the side wall of the circulation tank 6, so that oxidized air is supplied when the apparatus is started. The absorbing liquid is fed into the supply pipe 8 and the recovered liquid supply pipe 16, and solids such as gypsum accumulated in the pipes 8 and 16 can be removed. FIG. 9 shows an example in which the absorbing liquid is supplied by a blow-off pump. However, the same effect can be obtained by using an oxidizing air supply blower (not shown). When the apparatus is started, the oxidizing air supply blower supplies the oxidizing air 15 to the oxidizing air supply pipe 8 and the recovery liquid supply pipe 16 to remove the gypsum accumulated in the two-fluid nozzle 17.
[0042]
The embodiment shown in FIG. 10 differs from the embodiment shown in FIGS. 1 to 9 in that a two-fluid nozzle 17 which does not need to supply a liquid is used. In the embodiment shown in FIG. 10, when the oxidized air 15 supplied to the two-fluid nozzle 17 rises inside the two-fluid nozzle 17, the surrounding absorption liquid is sucked into the rising flow, and the air inside the two-fluid nozzle 17 becomes air. And the air 15 is miniaturized. By providing the two-fluid nozzle 17 capable of miniaturizing the air only by supplying the oxidizing air 15, there is no need to supply the recovered liquid. In addition, the blow-off pump 19 and its piping at the time of starting the apparatus shown in FIG. It becomes possible to remove the gypsum deposited in the nozzle 17.
[0043]
The embodiment shown in FIG. 11 differs from the embodiment shown in FIGS. 1 to 10 in that a vane 20 is provided at the discharge port of the two-fluid nozzle 17 and the flow of the discharged gas-liquid mixture is a swirling flow. By providing the vane 20 at the discharge port of the nozzle 17, the discharged gas-liquid mixed flow becomes a swirl flow, and in the swirl flow, the bubbles are dispersed into the circulation tank 6 and finer. Therefore, the oxidation efficiency can be further improved.
[0044]
【The invention's effect】
According to the present invention, the number of oxidizing agitators can be reduced or omitted, and fine oxidizing air bubbles can be uniformly supplied into the circulation tank. Further, by efficiently mixing the liquid having a high sulfurous acid concentration with the bubbles of the oxidizing air, the oxidizing performance of sulfurous acid can be improved. It is possible to provide a high-performance wet flue gas desulfurization apparatus and method with lower equipment and running costs than the prior art.
[Brief description of the drawings]
FIG. 1 is a side view of an absorption tower according to an embodiment of the present invention, in which a liquid recovery unit is provided on a side wall of an absorption tower, and the recovered liquid and oxidized air are supplied to a two-fluid nozzle to make air finer.
FIG. 2 is a cross-sectional view of the two-fluid nozzle of FIG.
FIG. 3 is a diagram comparing the oxidation rates of sulfurous acid between the conventional technology and the absorption tower of the embodiment shown in FIG.
FIG. 4 is a diagram of an absorption tower according to an embodiment of the present invention in which an absorption liquid is temporarily stored in a lower portion of a tower main body, and all of the absorption liquid is supplied to a two-fluid nozzle by a recovery liquid supply pipe.
FIG. 5 shows an absorption tower having a small circulation tank diameter according to an embodiment of the present invention, and a two-fluid nozzle is installed on a side surface of the tank.
FIG. 6 is a diagram of an absorption tower in which a two-fluid nozzle according to an embodiment of the present invention is horizontally installed at the bottom of a circulation tank.
FIG. 7 is a diagram of an absorption tower in which a two-fluid nozzle installed on a side surface of a circulation tank according to an embodiment of the present invention is directed toward the bottom of the tank.
FIG. 8 is a diagram of an absorption tower in which a pump is installed in a pipe for supplying a liquid from a liquid recovery unit to a two-fluid nozzle according to the embodiment of the present invention.
FIG. 9 is a diagram of an absorption tower in which a blow-off pump is installed in a pipe for supplying a liquid from a liquid recovery unit to a two-fluid nozzle according to an embodiment of the present invention.
FIG. 10 is a view showing a two-fluid nozzle which does not need to supply a liquid according to the embodiment of the present invention.
FIG. 11 is a view showing a two-fluid nozzle provided with a vane at a discharge port according to the embodiment of the present invention.
FIG. 12 is a diagram showing an absorption tower according to the related art.
FIG. 13 is a diagram showing an absorption tower according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Absorption tower main body 2 Inlet duct 3 Outlet duct 4 Absorbent circulation pump 5 Absorbent 6 Circulation tank 7 Stirrer 8 Air supply pipe 9 Mist eliminator 10 Absorbent extraction pipe 11 Circulation pipe 12 Spray header 13 Spray nozzle 14 Liquid recovery part 15 Oxidizing air Bubbles 16 Recovered liquid supply pipe 17 Two-fluid nozzle 18 Recovered liquid supply pump 19 Blow-off pump 20 Vane 21 Air supply hole 22 Absorbent liquid supply pipe

Claims (15)

Exhaust gas discharged from a combustion device such as a boiler is introduced from an inlet duct, and has an exhaust gas passage discharged from an outlet duct. Absorbent liquid extracted from a circulation tank is sprayed at a gas absorbing section to make gas-liquid contact with the exhaust gas. By doing so, in an absorption tower that treats sulfur oxides in exhaust gas, and in a wet flue gas desulfurization apparatus that includes a circulation tank that stores the absorbing solution that falls from the absorption tower,
Wet flue gas desulfurization characterized in that the circulation tank is provided with one or more two-fluid nozzles for mixing the absorption liquid and the oxidized air, which have been brought into gas-liquid contact with the exhaust gas in the absorption tower, and supplying the mixture to the circulation tank. apparatus. A liquid recovery section is provided at a position higher than the liquid level in the circulation tank in the absorption tower, and a recovery liquid supply pipe for supplying the recovery liquid from the liquid recovery section into the absorption liquid in the circulation tank and the oxidizing air in the absorption liquid in the circulation tank. 2. The wet flue gas desulfurization apparatus according to claim 1, wherein an oxidizing air supply pipe for supplying the inside is connected to a two-fluid nozzle. 3. The wet flue gas desulfurization apparatus according to claim 1, wherein one or more two-fluid nozzles are arranged on the bottom of the circulation tank or on the side wall facing the circulation tank. The wet flue gas desulfurization apparatus according to any one of claims 1 to 3, wherein the one or more two-fluid nozzles are arranged such that the two-fluid blowing direction is horizontal, substantially horizontal, or lower than the horizontal. The wet flue gas desulfurization apparatus according to any one of claims 1 to 4, wherein a vane is provided at a discharge port of the one or more two-fluid nozzles so that the gas-liquid mixed fluid forms a swirling flow. The liquid recovery section is provided in the entire horizontal or substantially horizontal cross section at the lower portion of the absorption tower for recovering all of the absorption liquid after being brought into gas-liquid contact with the exhaust gas in the absorption tower. Item 6. The wet flue gas desulfurization device according to any one of Items 1 to 5. The wet smoke exhaust according to any one of claims 1 to 6, wherein a pump for liquid circulation is arranged in a collection liquid supply pipe for supplying the collection liquid from the liquid collection section to one or more two-fluid nozzles. Desulfurization equipment. 3. A piping system connected to the supply pipe, wherein a blow-off pump for supplying an absorbent or air for discharging solids in the recovery liquid supply pipe and the oxidizing air supply pipe into the circulation tank is provided. 8. The wet flue gas desulfurization device according to any one of claims 7 to 7. Exhaust gas discharged from a combustion device such as a boiler is introduced from an inlet duct, and has an exhaust gas passage discharged from an outlet duct. Absorbent liquid extracted from a circulation tank is sprayed at a gas absorbing section to make gas-liquid contact with the exhaust gas. By doing so, in a wet flue gas desulfurization method using an absorption tower for treating sulfur oxides in exhaust gas and a circulation tank for storing the absorption liquid sprayed in the absorption tower,
A wet method characterized in that the absorbing liquid after gas-liquid contact with the exhaust gas in the absorption tower is mixed with the oxidizing air by one or more two-fluid nozzles while the oxidizing air is refined and supplied to the absorbing liquid in the circulation tank. Flue gas desulfurization method. 10. The wet flue gas desulfurization method according to claim 9, wherein the recovered liquid from the liquid recovery unit provided at a position higher than the liquid level of the circulation tank in the absorption tower is supplied to one or more two-fluid nozzles. 11. The wet flue gas desulfurization method according to claim 9, wherein bubbles discharged to one or more two-fluid nozzles are uniformly dispersed in the circulation tank. The gas-liquid mixed fluid discharged by one or more two-fluid nozzles is jetted horizontally or substantially horizontally or obliquely downward from the bottom or side surface of the circulation tank toward the bottom surface. The wet flue gas desulfurization method according to any one of the above. The wet flue gas desulfurization method according to any one of claims 9 to 12, wherein the gas-liquid mixed fluid is discharged into the absorbing liquid while being swirled by one or more two-fluid nozzles. The wet method according to any one of claims 9 to 13, wherein after collecting all of the absorbing liquid falling in the absorption tower in the liquid collecting part, the collected liquid is supplied to one or more two-fluid nozzles. Flue gas desulfurization method. It is characterized in that the solid matter in the gas-liquid mixed fluid of the absorbing liquid and the oxidizing air after being brought into gas-liquid contact with the exhaust gas in the absorption tower at the time of startup is discharged into the circulation tank from one or more two-fluid nozzles by the absorbing liquid or air. The wet flue gas desulfurization method according to any one of claims 9 to 14.

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