JP5281858B2 - Exhaust gas treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus of treating an exhaust gas, which can reduce further SO<SB>3</SB>contained in the exhaust gas without enlarging a wet type electric dust collector. <P>SOLUTION: The apparatus has a dust collector 6 collecting ash dust in combustion exhaust gas of a boiler 2, wet desulfurization equipment 8 removing sulfur oxides from the exhaust gas discharged from the dust collector 6 by using a desulfurization agent slurry, and the wet type electric dust collector 9 collecting mist from the exhaust gas discharged from the wet desulfurization equipment 8. Charging equipment 7 charging mist in the exhaust gas is provided on an exhaust gas passage between the dust collector 6 and the wet desulfurization equipment 8. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to an exhaust gas treatment device, and more particularly to an exhaust gas treatment device that efficiently reduces SO ₃ mist contained in combustion exhaust gas of a boiler.

  In boilers used in thermal power plants and the like, exhaust gas generated by burning, for example, coal, which is fossil fuel, is released to the atmosphere after removing harmful components contained in the gas with an exhaust gas treatment device. As such an exhaust gas treatment device, a denitration device that removes nitrogen oxides in boiler combustion exhaust gas, a dust collector that collects soot in exhaust gas discharged from the denitration device, and a dust collector There is known a wet desulfurization apparatus that removes sulfur oxides in exhaust gas using a desulfurizing agent slurry and a wet electric dust collector that collects mist in exhaust gas discharged from the wet desulfurization apparatus.

As a method for reducing SO ₃ contained in exhaust gas, Patent Document 1 discloses that activated carbon fiber adsorbs sulfur dioxide (SO ₂ ) in gas and oxidizes it to SO ₃ , and then supplies water to dilute rare gas. A wet desulfurization apparatus that removes sulfuric acid (H ₂ SO ₄ ) is described. In particular, the removal rate of SO ₃ mist is increased by providing a pair of electrification units in the vicinity of the nozzle outlet for supplying water, and absorbing the SO ₃ mist in the charged water droplets supplied from the nozzle. Has been proposed.

On the other hand, Patent Document 2 proposes that an electrostatic precipitator is provided at the inlet of the wet desulfurization apparatus to collect soot containing SO ₃ reactant with the electrostatic precipitator. In addition, it has been proposed to increase the SO ₃ removal rate by spraying water to the exhaust gas discharged from the electrostatic precipitator to adsorb charged dust in the exhaust gas.

JP 2007-14931 A JP-A-11-137954

However, although it is desired to collect SO ₃ mist with higher efficiency, the conventional technique is not sufficient. For example, when trying to reduce SO ₃ mist with a wet electrostatic precipitator in the final process, there is a problem that the wet electrostatic precipitator becomes large.

The problem to be solved by the present invention is to further reduce SO ₃ mist contained in the exhaust gas without increasing the size of the wet electrostatic precipitator.

  In order to solve the above-described problem, an exhaust gas treatment apparatus according to a first aspect of the present invention includes an air heater and a gas cooler that recovers heat in a combustion exhaust gas of a boiler, and dust in the exhaust gas from which heat is recovered by the air heater and the gas cooler. A dust collector for collecting, a wet desulfurizer for removing sulfur oxides in the exhaust gas discharged from the dust collector using a desulfurizing agent slurry, and a mist in the exhaust gas discharged from the wet desulfurizer. In the exhaust gas treatment apparatus including a wet electric dust collector that collects, a charging device that charges mist in the exhaust gas is provided in an exhaust gas flow path between the dust collector and the wet desulfurization apparatus. .

That is, the temperature of the exhaust gas discharged from the dust collector is partly recovered by the air heater and gas cooler upstream of the dust collector, and is usually below the acid dew point, so SO ₃ mist is included. According to the present invention, the SO ₃ mist contained in the exhaust gas discharged from the dust collector is charged by the charging device, and the charged SO ₃ mist flows into the wet desulfurization device together with the gas and is adsorbed by the desulfurizing agent slurry. The reaction is removed. At this time, the SO ₃ mist is adsorbed to the droplets of the desulfurizing agent slurry by the Coulomb force of the electric charge, so that the removal rate of the SO ₃ mist in the wet desulfurization apparatus is increased. Since the SO ₃ mist that could not be removed by the wet desulfurization apparatus is collected by the wet electrostatic precipitator, SO ₃ contained in the exhaust gas can be further reduced, and in the gas flowing into the wet electrostatic precipitator Since the amount of SO ₃ mist is small, the wet electrostatic precipitator can be downsized.

  In order to solve the above problems, an exhaust gas treatment apparatus according to a second aspect of the present invention includes a dust collector that collects dust in the combustion exhaust gas of a boiler, and traps dust in the exhaust gas discharged from the dust collector. A wet dust collector for collecting, a wet desulfurizer for removing sulfur oxides in the exhaust gas discharged from the wet dust collector using a desulfurizing agent slurry, and a wet for collecting mist in the exhaust gas discharged from the wet desulfurizer An exhaust gas treatment apparatus including an electric dust collector is characterized in that a charging device for charging mist in the exhaust gas is provided in an exhaust gas flow path between the wet dust collector and the wet desulfurization device.

That is, since the temperature of the exhaust gas discharged from the wet dust collector is usually below the acid dew point, SO ₃ mist is included. According to the present invention, the SO ₃ mist contained in the exhaust gas discharged from the wet dust collector is charged by the charging device, and the charged SO ₃ mist flows into the wet desulfurization device together with the gas and is adsorbed by the desulfurization agent slurry. The reaction is removed. At this time, the SO ₃ mist is adsorbed to the droplets of the desulfurizing agent slurry by the Coulomb force of the electric charge, so that the removal rate of the SO ₃ mist in the wet desulfurization apparatus is increased. Since the SO ₃ mist that could not be removed by the wet desulfurization apparatus is collected by the wet electrostatic precipitator, SO ₃ contained in the exhaust gas can be further reduced, and in the gas flowing into the wet electrostatic precipitator Since the amount of SO ₃ mist is small, the wet electrostatic precipitator can be downsized.

In the exhaust gas treatment apparatus according to the first or second aspect of the present invention, the exhaust gas flow path in which the charging device is provided has two divided flow paths that are connected in parallel and each provided with the charging device, The two charging devices provided in the two divided flow paths can be positive or negative or the same in polarity. According to this, the aggregation effect of SO ₃ mist can be obtained by changing the polarity of the charge to positive and negative. However, even with the same polarity, the removal rate in the wet desulfurization apparatus increases. Two dust collectors are provided to individually collect the dust in the combustion exhaust gas of the two boilers, and the two exhaust gas flow paths of the exhaust gas discharged from the two dust collectors are Each of the two exhaust gas channels is connected to a single exhaust gas flow channel connected to a wet desulfurization device, and charging devices for charging mist in the exhaust gas are provided. Or they can be the same.

In the exhaust gas treatment apparatus according to the first or second aspect of the present invention, the wet desulfurization apparatus is provided with a charge spray device that charges a part of a nozzle that sprays the desulfurization agent slurry, and the charge spray device includes the charge spray device. It is preferable to charge a positive or negative charge different from that of the device. As a result, some of the slurry droplets sprayed in the wet desulfurization apparatus are charged to a different charge from the charged mist, so that the SO ₃ mist and the desulfurization agent slurry droplets approach each other. Are attracted to each other by the coulomb force of each other, and the SO ₃ mist is adsorbed to the droplets of the desulfurizing agent slurry. Therefore, the removal rate of SO ₃ mist in the wet desulfurization apparatus becomes higher.

  An exhaust gas treatment apparatus according to a third aspect of the present invention includes a dust collector that collects soot and dust in boiler combustion exhaust gas, and wet desulfurization that removes sulfur oxides in the exhaust gas discharged from the dust collector. In an exhaust gas treatment apparatus comprising a device and a wet electrostatic precipitator that collects mist in exhaust gas discharged from the wet desulfurization device, the exhaust gas flow path between the wet desulfurization device and the wet electrostatic precipitator, A charging device for charging mist in the exhaust gas is provided.

According to the present invention, the SO ₃ mist that could not be removed by the wet desulfurization apparatus flows into the charging device and is charged, and the charged SO ₃ mist flows into the wet electrostatic precipitator, for example, the dust collecting of the wet electrostatic precipitator. It is collected on the plate and removed. At this time, the SO ₃ mist is adsorbed to the dust collecting plate by the coulomb force of the electric charge, so that the removal rate of the SO ₃ mist in the wet electric dust collector is increased. Therefore, SO ₃ contained in the exhaust gas can be further reduced, and since the removal rate of SO ₃ mist in the wet electrostatic precipitator is high, the wet electrostatic precipitator can be downsized.

In this case, in the exhaust gas flow path between the charging device and the wet electrostatic precipitator, a charging spray device that sprays a liquid charged with positive or negative charges different from the charging device in the exhaust gas is provided. Is preferred. As a result, since the water droplets sprayed by the charge spray device are charged to a different charge from the charged mist, when the SO ₃ mist and the spray water droplets approach each other, they are attracted by the coulomb force of each other. ₃ mist adsorbs on spray water droplets with a large particle size. Therefore, the removal rate of SO ₃ mist in the wet electrostatic precipitator becomes higher.

In this case, the exhaust gas flow path in which the charging device is provided has two divided flow paths that are connected in parallel and each provided with the charging device, and the two charging charges that are provided in the two divided flow paths. The device can have a positive or negative charge polarity. According to this, the aggregation effect of SO ₃ mist can be obtained by changing the polarity of the charge to positive and negative. However, even with the same polarity, the removal rate in the wet desulfurization apparatus increases. In addition, the exhaust gas flow path in which the charging device is provided has two divided flow paths that are connected in parallel and each provided with the charging device, and the two divided flow paths are different from the charging device. A charge spray device that charges positive or negative charges may be provided.

According to the present invention, SO ₃ contained in the exhaust gas can be further reduced without increasing the size of the wet electrostatic precipitator.

  Hereinafter, an embodiment of an exhaust gas treatment apparatus according to the present invention will be described with reference to FIGS.

(First embodiment)
FIG. 1 is a diagram showing an overall configuration of an exhaust gas treatment apparatus according to a first embodiment of the present invention. As shown in FIG. 1, the exhaust gas treatment apparatus 1 of the first embodiment treats exhaust gas discharged from a coal fired boiler 2 that burns fossil fuel, for example, coal, and generates steam by its heat, In order from the upstream side of the exhaust gas, for example, a denitration device 3, an air heater (A / H) 4, a gas cooler 5, a dust collector 6, a charging device 7, a wet desulfurization device 8, a wet electric dust collector 9, an induction blower not shown, A chimney 15 or the like is provided. The apparatuses are connected to each other by, for example, a substantially rectangular exhaust gas duct 11 that forms an exhaust gas flow path.

  The denitration apparatus 3 removes nitrogen oxide (NOx) in exhaust gas by a selective catalytic reduction reaction using ammonia as a reducing agent, for example, using a denitration catalyst. The air heater 4 heats the combustion air of the coal fired boiler 2 by exchanging heat. The gas cooler 5 is for lowering the temperature of the exhaust gas at the outlet of the air heater 4. For example, the gas cooler 5 heats the exhaust gas discharged from the wet electrostatic precipitator 9 with the recovered heat to prevent purple smoke from being generated from the chimney 15. It may be like a gas heater. The dust collector 6 collects soot and mist in the exhaust gas and is not particularly limited as long as it can collect soot and mist in the gas, and an electric dust collector, a bag filter, or the like is used.

  The charging device 7 charges the mist in the exhaust gas, and is preferably provided at a location where the exhaust gas temperature is below the acid dew point. The charging device 7 is not particularly limited as long as the mist in the exhaust gas can be charged. For example, the discharge electrode and the counter electrode are provided to face each other with a predetermined interval between the discharge electrode and the counter electrode. A gas or the like that charges the mist in the gas is used.

  The wet desulfurization apparatus 8 removes sulfur oxides in exhaust gas using a desulfurization agent slurry. In the wet desulfurization apparatus 8, for example, a plurality of nozzles for spraying a desulfurization agent slurry such as limestone are provided at predetermined intervals in the vertical direction, and droplets of the desulfurization agent slurry sprayed from the plurality of nozzles are wet desulfurization apparatus. In the process of falling inside the wet desulfurizer 8, the sulfur oxide in the exhaust gas reacts with the desulfurizing agent and is absorbed and removed by contact between the exhaust gas rising in the wet desulfurization apparatus 8 and the desulfurizing agent slurry.

The wet electrostatic precipitator 9 collects and removes mist and dust in the exhaust gas discharged from the wet desulfurization apparatus 8, and sets the SO ₃ concentration in the exhaust gas discharged from the chimney 15 to the atmosphere below a predetermined value. It is necessary for As the wet electrostatic precipitator 9, for example, a discharge electrode and a flat or cylindrical dust collection electrode are provided facing each other with a predetermined interval, and the discharge electrode and the dust collection are collected while dropping water on the dust collection electrode surface. Exhaust gas is allowed to flow between the electrode and mist or dust in the gas, for example, is charged with a negative polarity and collected by a positive polarity dust collecting electrode for removal.

Next, the operation of the exhaust gas treatment apparatus 1 of the first embodiment will be described. The high-temperature combustion exhaust gas discharged from the coal fired boiler 2 is subjected to removal of NOx in the exhaust gas by the denitration device 3, and then a part of the heat is recovered by the air heater 4 and the gas cooler 5, for example, 110 to 90 ° C. To be cooled. When the exhaust gas reaches 110 to 90 ° C. below the acid dew point (approximately 150 to 160 ° C.), a part of SO _{3 in} the gas becomes mist. For example, when coal burns, sulfur (S) in the coal is released in the form of gas, and most of it becomes sulfur dioxide (SO ₂ ), but a part of SO ₂ is heated by the exhaust gas by the air heater 4 or the gas cooler 5. When it is recovered, it is oxidized to SO ₃ . The ratio from SO ₂ to SO ₃ varies depending on the type of coal and the operating conditions of the boiler 2 (air ratio, gas temperature, etc.), but is about 1 to 3%. Further, SO ₂ in the exhaust gas undergoes an oxidation reaction of SO ₃ in the denitration device 3. The ratio varies depending on the type of the denitration device 3, but is about 0.5 to 2%. A part of the SO ₃ becomes mist when the gas temperature is below the acid dew point. The SO ₃ mist floats in the exhaust gas and flows together with the exhaust gas, and the exhaust gas containing the SO ₃ mist flows into the dust collector 6.

In the dust collector 6, most of the dust and SO ₃ mist in the exhaust gas are collected by the dust collector 6. The SO ₃ mist that has not been collected by the dust collector 6 flows into the charging device 7 together with the exhaust gas, where it is charged to a positive or negative polarity. The charged SO ₃ mist flows into the wet desulfurization device 8 together with the exhaust gas, and rises in the wet desulfurization device 8. Sulfur oxides (SO ₂ and SO ₃ ) contained in the exhaust gas come into contact with droplets of the desulfurizing agent slurry sprayed from the nozzle and react with the desulfurizing agent to be absorbed and removed.

The SO ₃ mist collides with the desulfurizing agent slurry while being elevated in the wet desulfurization apparatus 8 and is absorbed and removed by reaction. For example, in the wet desulfurization apparatus 8, since the gas temperature is lowered to about 50 to 60 ° C. below the acid dew point, SO ₃ becomes a fine mist of 1 μm or less, and the removal rate of this SO ₃ mist is determined by the wet desulfurization apparatus. Although it changes with the structure of 8, it is generally about 60 to 80%. However, in the present embodiment, since the SO ₃ mist is charged by the charging device 7, the SO ₃ mist is adsorbed to the droplets of the desulfurizing agent slurry by the electrostatic attraction force. That is, the SO ₃ mist is adsorbed to the water droplets by electrostatic attraction when approaching the droplets of the desulfurizing agent slurry. Therefore, the removal rate of SO ₃ mist in the wet desulfurization apparatus 8 can be set to 60 to 80% or more. Thus, since the removal rate of SO ₃ mist in the wet desulfurization apparatus 8 is increased, the amount of SO ₃ mist that has not been removed by the wet desulfurization apparatus 8 is reduced.

The SO ₃ mist that could not be removed by the wet desulfurization apparatus 8 flows into the wet electrostatic precipitator 9 together with the exhaust gas and is collected together with soot, and the exhaust gas is discharged from the chimney 15 to the atmosphere. In the wet electrostatic precipitator 9, the larger the particle size of the SO ₃ mist, the easier it is to collect. Therefore, the removal rate in the wet electrostatic precipitator 9 increases. For example, the relationship of SO ₃ mist removal rate of the (SO ₃ removal rate) SO ₃ mist average particle diameter in the wet electrostatic precipitator 9, as shown in FIG. 13, as the particle diameter of the SO ₃ mist is large SO ₃ It is known from the fact that the removal rate of mist is high.

Thus, since the amount of SO ₃ mist in the gas flowing into the wet electrostatic precipitator 9 is small and the removal rate is high, the wet electrostatic precipitator 9 can be downsized. As a result, in the wet electrostatic precipitator 9, when SO ₃ mist adheres to the dust collecting electrode, it reacts with moisture in the exhaust gas to form a strongly acidic aqueous solution. Therefore, the material used for the wet electrostatic precipitator 9 is made of a corrosion-resistant material. Although it is necessary to employ, the wet electrostatic precipitator 9 can be reduced in size, so that the equipment cost can be reduced.

Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9. For example, the amount of SO ₃ is about several% with respect to SO _2, SO ₃ is a harmful substance, and, since the cause of tobacco smoke when discharged from the stack 15, the emission concentration e.g. 1 ppm or less, that is, the removal rate of SO ₃ can be 90 to 99% or more, for example, 99% or more.

(Second Embodiment)
FIG. 2 is a diagram showing an overall configuration of an exhaust gas treatment apparatus according to a second embodiment of the present invention. As shown in FIG. 2, the exhaust gas treatment device 20 of the second embodiment is different only in that a charge spray device 21 is provided in the wet desulfurization device 8 in the exhaust gas treatment device 1 of the first embodiment. Since the other configuration is the same, the same functional parts are denoted by the same reference numerals and description thereof is omitted.

  The charging spray device 21 charges a part of the nozzle for spraying the desulfurizing agent slurry and charges the slurry droplet sprayed from the nozzle. The charging spray device 21 may be configured in any way as long as the slurry droplets can be charged. The charging spray device 21 preferably charges positive or negative charges having a polarity opposite to that of the charging device 7. The installation location of the charge spray device 21 is not particularly limited, and may be on the gas inlet side or the outlet side. For example, in the example of FIG. That is, the charging spray device 21 is arranged so as to charge the uppermost nozzle of the wet desulfurization device 8.

With this configuration, in the wet desulfurization apparatus 8, a droplet of the desulfurization agent slurry sprayed from the charged nozzle is included in the charging spray device 21, and this droplet is charged with a polarity opposite to that of the charging device 7. Has been. For this reason, when the charged SO ₃ mist rising in the wet desulfurization apparatus 8 and the droplet of the desulfurizing agent slurry having the opposite polarity approach each other, the SO ₃ mist is attracted by the coulomb force of each other and the SO ₃ mist is the droplet of the desulfurizing agent slurry. To be adsorbed.

The diameter of the SO ₃ mist is discharged from the wet desulfurization system 8, as shown in FIG. 6, the diameter of the SO ₃ mist is increased by applying a charge as compared to a blank test which does not over charged, In the wet desulfurization apparatus 8, the probability of contact with the droplets of the desulfurizing agent slurry increases.

Therefore, the removal rate of SO ₃ mist in the wet desulfurization apparatus 8 becomes higher. Even if the SO ₃ mist cannot be completely removed by the wet desulfurization device 8, it is removed by the wet electrostatic precipitator 9. At this time, if the diameter of the SO ₃ mist is large, it is collected by the wet electrostatic precipitator 9. Since it becomes easy, the removal rate in the wet electrostatic precipitator 9 becomes high. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

(Third embodiment)
FIG. 3 is a diagram showing an overall configuration of an exhaust gas treatment apparatus according to a third embodiment of the present invention. As shown in FIG. 3, the exhaust gas treatment device 30 of the third embodiment omits the gas cooler 5 in the exhaust gas treatment device 1 of the first embodiment and is downstream of the dust collector 6 (actually the dust collector 6 The wet dust collector 12 is provided between the charging device 7 and the charging device 7. Since the other configuration is the same, the same functional parts are denoted by the same reference numerals and description thereof is omitted.

  As the wet dust collector 12, for example, as shown in FIG. 5, one having a nozzle 12 a for spraying spray water in the exhaust gas duct 11 is used. Specifically, the size of the exhaust gas duct 11 is gradually reduced, and the nozzle 12a is installed in the exhaust gas duct 11 so as to spray the spray water against the gas flow in the reduced portion 11a. It collects dust and mist.

With this configuration, for example, the exhaust gas temperature flowing into the dust collector 6 is about 160 ° C. When the exhaust gas collected by the dust collector 6 is collected by the wet dust collector 12, the gas temperature is The temperature drops below the acid dew point. Therefore, the gas discharged from the wet dust collector 12, contains SO ₃ mist, the SO ₃ mist is charged at charging device 7. The charged SO ₃ mist flows into the wet desulfurization apparatus 8 as described above, and is adsorbed and removed by the desulfurization agent slurry. Therefore, since the removal rate of SO ₃ mist in the wet desulfurization apparatus 8 is increased, SO ₃ contained in the exhaust gas can be efficiently further reduced without increasing the size of the wet electrostatic precipitator 9.

(Fourth embodiment)
FIG. 4 is a diagram showing an overall configuration of an exhaust gas treatment apparatus according to a fourth embodiment of the present invention. FIG. 5 is a view showing a main part of the exhaust gas treatment apparatus of the fourth embodiment according to the present invention. As shown in FIGS. 4 and 5, the exhaust gas treatment device 40 of the fourth embodiment charges part of the nozzle 8 a that causes the wet desulfurization device 8 in the exhaust gas treatment device 1 of the third embodiment to spray the desulfurization agent slurry. The difference is that a charging spray device 41 is provided. Since the other configuration is the same, the same functional parts are denoted by the same reference numerals and description thereof is omitted.

  In the charging device 7, for example, the discharge electrode plate 7a and the counter electrode plate 7b are provided to face each other with a predetermined interval, and an exhaust gas is allowed to flow between the discharge electrode plate 7a and the counter electrode plate 7b. The mist is charged positively or negatively (positively in the illustrated example).

  The charging spray device 41 charges a part of the nozzle 8a for spraying the desulfurizing agent slurry to charge the slurry droplet sprayed from the nozzle 8a. The charging spray device 41 may be any device as long as it can charge the slurry droplets. Further, the charge spray device 41 is preferably charged with a negative or positive charge in the example shown in FIG. The installation location of the charge spray device 41 is not particularly limited, and may be on the gas inlet side or the outlet side, for example, on the inlet side. That is, the charge spray device 41 is provided so as to charge the lower nozzle 8a of the wet desulfurization device 8.

With such a configuration, in the wet desulfurization apparatus 8, a droplet of the desulfurization agent slurry sprayed from the charged nozzle is included in the charge spray device 21, and the droplet has a charge having a polarity opposite to that of the charging device 7. Is charged. For this reason, when the charged SO ₃ mist rising in the wet desulfurization apparatus 8 and the desulfurizing slurry slurry charged in the opposite polarity approach each other, the SO ₃ mist attracts the desulfurizing agent slurry by mutual coulomb force. Adsorbed to the droplet.

Further, as shown in FIG. 6, the diameter of the SO ₃ mist discharged from the wet desulfurization apparatus 8 is larger than that in the case of the blank test in which no charge is applied, and compared with the case where only the charge is applied. In addition, since the diameter of the SO ₃ mist is further increased, the probability of contact with the droplets of the desulfurizing agent slurry in the wet desulfurization apparatus 8 is increased.

Therefore, the removal rate of SO ₃ mist in the wet desulfurization apparatus 8 becomes higher. In addition, the SO ₃ mist is removed by the wet electrostatic precipitator 9 even if it is not removed by the wet desulfurization device 8. At this time, if the diameter of the SO ₃ mist is large, it is easily collected by the wet electrostatic precipitator 9. Thus, the removal rate in the wet electrostatic precipitator 9 is increased. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

(Fifth embodiment)
FIG. 7 is a view showing a main part of an exhaust gas treatment apparatus according to a fifth embodiment of the present invention. As shown in FIG. 7, the exhaust gas treatment device 50 of the fifth embodiment divides the inside of the exhaust gas duct 11 (exhaust gas flow path) in which the charging device 7 is provided into two divided flow paths 11 b and 11 c. The charging device 7 is provided. Since the exhaust gas treatment apparatus 50 of the fifth embodiment shows another example in the case of providing the charging device 7 in the exhaust gas treatment apparatus of the first to fourth embodiments, only the main part is shown in FIG. . Since the other configuration is the same, the same functional parts are denoted by the same reference numerals and description thereof is omitted.

  A partition plate 13 extending in the gas flow direction is provided in the middle of the exhaust gas duct 11, and the interior of the exhaust gas duct 11 is divided into two divided flow paths 11b and 11c. The two divided flow paths 11b and 11c are connected in parallel by providing the partition plate 13 in the exhaust gas duct 11, but the invention is not limited to this. For example, the exhaust gas duct 11 is branched into two ducts and joined again. You may make it form. A charging device 7 is provided in each of the two divided flow paths 11b and 11c.

  As the two charging devices 7, for example, a discharge electrode 7 c is provided at a substantially central portion of the divided flow paths 11 b and 11 c, and an inner wall forming the divided flow paths 11 b and 11 c and an inner wall of the partition plate are formed as counter electrodes. . The discharge electrode 7c is, for example, provided with a plurality of stages (for example, six stages) of linear electrode portions 7d extending in the gas flow direction, and connecting both ends of the electrode portions 7d to flow through the divided flow paths 11b and 11c. Are preferably charged substantially uniformly. The structure of the discharge electrode 7c is not particularly limited, but the mist can be charged substantially uniformly using another structure such as a mesh electrode. The two charging devices 7 may have either the same polarity or the opposite polarity, but it is preferable that the polarity of the charging be reversed.

  When the charging polarities of the two charging devices 7 are the same, the exhaust gas discharged from the dust collecting device 6 is divided into two in the middle of flowing through the exhaust gas duct 11 and enters the two divided flow paths 11b and 11c, respectively. Inflow. The mist contained in the exhaust gas flowing into the two divided flow paths 11b and 11c is charged to the same polarity by the respective charging devices 7, and then merges and flows into the wet desulfurization device 8, so that the first -There exists an effect substantially the same as the exhaust gas processing apparatus of 4th Embodiment.

On the other hand, when the charging polarities of the two charging devices 7 are opposite, the mists contained in the two exhaust gases are charged to the opposite polarities by the two charging devices 7. When the two exhaust gases are merged, when mists having opposite polarities approach each other, they are attracted and aggregated by the mutual Coulomb force, resulting in a mist having a large particle diameter. The mist having a large particle diameter flows into the wet desulfurization device 8 together with the exhaust gas and rises in the wet desulfurization device 8. Since the mist has a large particle size, the probability of being absorbed and removed by colliding with the desulfurizing agent slurry while rising in the wet desulfurization apparatus 8 is increased, so that the SO ₃ mist is removed by the wet desulfurization apparatus 8. The rate will be higher. Also, in the wet electrostatic precipitator 9, if the mist has a large particle size, the mist removal rate increases. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

  In addition, although the inside of the exhaust gas duct 11 in which the charging device 7 is provided is divided into two and the charging device 7 is provided in each of the two divided flow paths 11b and 11c, the present invention is not limited to this. The charging device may be provided in each of the divided flow paths divided into three or more and divided into three or more.

(Sixth embodiment)
FIG. 8 is a view showing a part of an exhaust gas treatment apparatus according to a sixth embodiment of the present invention. As shown in FIG. 8, the exhaust gas treatment apparatus 60 of the sixth embodiment removes NOx and soot contained in the gas from the combustion exhaust gas discharged from the two coal fired boilers 2, respectively, And the sulfur oxide is removed by one wet desulfurization apparatus 8. The same functional parts as those in the exhaust gas treatment apparatus of the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The exhaust gas treatment device 60 of the sixth embodiment processes the combustion exhaust gas discharged from the two coal fired boilers 2, and the two first exhaust gas ducts into which the combustion exhaust gas discharged from the two coal fired boilers 2 flows. 61 and the second exhaust gas duct 62, and the first exhaust gas duct 61 and the second exhaust gas duct 62 are connected to each other to join the two exhaust gases to guide the exhaust gas. The first exhaust gas duct 61 and the second exhaust gas duct 62 are respectively provided with a denitration device 3, an air heater 4, a gas cooler 5, a dust collector 6, a charging device 7 and the like in order from the upstream side of the exhaust gas. The third exhaust gas duct 63 is provided with a wet desulfurization device 8, a wet electric dust collector 9, an induction blower (not shown), a chimney 15, and the like. The two charging devices 7 may have either the same polarity or the opposite polarity.

  When the charging polarities of the two charging devices 7 are the same, the mist contained in the exhaust gas discharged from each dust collecting device 6 is charged to the same polarity by each charging device, and merges to wet. It flows into the desulfurization device 8. For this reason, there exists an effect substantially the same as the exhaust gas processing apparatus 1, 20, 30, 40 of said 1st-4th embodiment.

On the other hand, when the charging polarities of the two charging devices 7 are opposite, the mists contained in the two exhaust gases are charged to the opposite polarities by the two charging devices 7. When the two exhaust gases are merged, when mists having opposite polarities approach each other, they are attracted and aggregated by the mutual Coulomb force, resulting in a mist having a large particle diameter. The mist having a large particle diameter flows into the wet desulfurization device 8 together with the exhaust gas and rises in the wet desulfurization device 8. Since the mist has a large particle size, the probability of being absorbed and removed by colliding with the desulfurizing agent slurry while rising in the wet desulfurization apparatus 8 is increased, so that the SO ₃ mist is removed by the wet desulfurization apparatus 8. The rate will be higher. Also, in the wet electrostatic precipitator 9, if the mist has a large particle size, the mist removal rate increases. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

Next, the removal rate of SO ₃ in the wet electrostatic precipitator 9 depending on whether or not the mist is charged was examined using the exhaust gas treatment device 60 of the sixth embodiment. Dust collector (DEP) 4 outlet of the SO ₃ concentration and the wet electrostatic precipitator (W-EP) 9 measures the SO ₃ concentration at the outlet, the dust collecting device (DEP) 4 SO ₃ concentration in the outlet as 1, a wet electrostatic precipitator (W-EP) The value at 9 outlets was determined. When the two charging devices 7 were turned on (when the charging polarities of the two charging devices 7 were reversed), the SO ₃ removal rate was 94.5% at 0.055. On the other hand, when the charging device 7 was turned off, the SO ₃ removal rate was 89% at 0.090. As a result, it was found that the SO ₃ removal rate can be reduced to about ½ by turning on the charging device 7. Therefore, in order to obtain an equivalent SO ₃ removal rate without using a charging device, it is necessary to increase the size of the wet electrostatic precipitator by 40%. By installing the charging device according to the present invention, the size of the wet electrostatic precipitator is increased. The effect that can reduce the thickness was confirmed.

  In addition, although the case of the combustion exhaust gas from two coal fired boilers 2 was demonstrated, it is not limited to this, Even when the combustion exhaust gas from three or more coal fired boilers is processed, the exhaust gas treatment of the sixth embodiment It goes without saying that the device can be applied.

(Seventh embodiment)
FIG. 9 is a diagram showing an overall configuration of an exhaust gas treatment apparatus according to a seventh embodiment of the present invention. The exhaust gas treatment apparatuses of the seventh embodiment and the eighth to tenth embodiments described later are exhaust gas treatment apparatuses having a different form from the exhaust gas treatment apparatuses of the first to sixth embodiments. As shown in FIG. 9, the exhaust gas treatment device 70 of the seventh embodiment is, for example, sequentially from the upstream side of the combustion exhaust gas discharged from the coal fired boiler 2, for example, a denitration device 3, an air heater 4, a dust collector 6, wet desulfurization. A device 8, a charging device 7, a wet electrostatic precipitator 9, an induction blower (not shown), a chimney 15 and the like are provided. Each apparatus is mutually connected by the exhaust gas duct 11 which forms an exhaust gas flow path.

  The charging device 7 is not particularly limited as long as the mist in the exhaust gas can be charged. For example, the discharge electrode and the counter electrode are provided to face each other with a predetermined interval between the discharge electrode and the counter electrode. A gas or the like that charges the mist in the gas is used. The polarity of the charging of the charging device is not particularly limited, whether positive or negative. For example, the mist is negatively charged by corona discharge. Thereby, in the case where the wet electrostatic precipitator 9 has a structure in which mist or the like is collected by a positive polarity dust collecting electrode, it is easily collected by the dust collecting electrode.

  As the wet electrostatic precipitator 9, for example, a discharge electrode and a flat or cylindrical dust collection electrode are provided facing each other with a predetermined interval, and the discharge electrode and the dust collection are collected while dropping water on the dust collection electrode surface. Exhaust gas is allowed to flow between the electrode and mist or dust in the gas, for example, is charged with a negative polarity and collected by a positive polarity dust collecting electrode for removal.

If comprised in this way, after high temperature combustion exhaust gas discharged | emitted from the coal fired boiler 2 removes NOx in exhaust gas with the NOx removal apparatus 3, after a part of the heat | fever is collect | recovered with the air heater 4, it will be a dust collector. 6 flows in. In the dust collector 6, dust and mist in the exhaust gas are collected. The exhaust gas discharged from the dust collector 6 flows into the wet desulfurizer 8 and rises in the wet desulfurizer 8. Sulfur oxides (SO ₂ and SO ₃ ) contained in the exhaust gas come into contact with droplets of the desulfurizing agent slurry sprayed from the nozzle and react with the desulfurizing agent to be absorbed and removed.

Since the wet desulfurization system within 8 gas temperature is below the acid dew point in the gas contains SO ₃ mist, SO ₃ mist is absorbed by collisions with the desulfurizing agent slurry during the rise of the wet desulfurization apparatus 8 The reaction is removed. For example, in the wet desulfurization apparatus 8, the gas temperature decreases to about 50 to 60 ° C. below the acid dew point, so SO ₃ becomes a fine mist of 1 μm or less. The removal rate of this SO ₃ mist is the same as that of the wet desulfurization apparatus 8. Although it varies depending on the structure, it is generally about 60 to 80%.

The SO ₃ mist that could not be removed by the wet desulfurization device 8 flows into the charging device 7 together with the exhaust gas, and is charged, for example, with a negative polarity. The charged SO ₃ mist flows into the wet electrostatic precipitator 9 together with the exhaust gas and is collected together with the dust, and the exhaust gas is discharged from the chimney 15 to the atmosphere. In the wet type electrostatic precipitator 9, gas flows between the discharge electrode and the dust collecting electrode, and mist or dust in the gas is charged to, for example, a negative polarity and collected by the dust collecting electrode having a positive polarity. At this time, since the SO ₃ mist is charged with a negative polarity, the SO ₃ mist is efficiently collected on the dust collecting plate by the Coulomb force of the charge.

Thus, since the removal rate of SO ₃ mist increases, the size of the wet electrostatic precipitator 9 can be reduced. As a result, in the wet electrostatic precipitator 9, when SO ₃ mist adheres to the dust collecting electrode, it reacts with moisture in the exhaust gas to form a strongly acidic aqueous solution. Therefore, the material used for the wet electrostatic precipitator 9 is made of a corrosion-resistant material. Although it is necessary to employ, the wet electrostatic precipitator 9 can be reduced in size, so that the equipment cost can be reduced. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

(Eighth embodiment)
FIG. 10 is a diagram showing an overall configuration of an exhaust gas treatment apparatus according to an eighth embodiment of the present invention. As shown in FIG. 10, the exhaust gas treatment device 80 of the eighth embodiment includes a charged spray device 10 in the exhaust gas duct 11 between the wet desulfurization device 8 and the wet electrostatic precipitator 9 in the exhaust gas treatment device 70 of the seventh embodiment. The only difference is that it is provided. Since the other configuration is the same, the same functional parts are denoted by the same reference numerals and description thereof is omitted.

  The charging spray device 10 may be any device as long as it sprays a liquid (for example, water) into the exhaust gas duct 11 and the sprayed liquid is charged. Further, the charge spray device 10 may have the same polarity of the spray liquid as the charge device 7, but is preferably positive or negative, for example, positive, opposite to the charge device 7.

According to this structure, the liquid which is charged to the opposite polarity for example the positive polarity is sprayed from the charging device 7 by the charged spray device 10 into the flue gas duct 11 to SO ₃ mist charged by charging device 7 passes. As a result, when the charged SO ₃ mist and the spray droplet charged to the opposite polarity approach each other, the SO ₃ mist is attracted by the mutual Coulomb force and absorbed by the spray droplet having a large particle diameter. Thus, the SO ₃ mist is absorbed by the spray droplets having a large particle diameter and flows into the wet electrostatic precipitator 9 in a state where the particle diameter is large, so that it is easy to be collected by the wet electrostatic precipitator 9. The removal rate of SO ₃ mist in the electric dust collector 9 becomes higher. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

(Ninth embodiment)
The exhaust gas treatment apparatus of the ninth embodiment is characterized in that the inside of an exhaust gas duct provided with a charging device is divided into two to form two divided flow paths, and the charging devices are provided in the two divided flow paths, respectively. It is said. The exhaust gas treatment apparatus of the ninth embodiment shows another example in the case where the charging device in the exhaust gas treatment apparatus of the seventh and eighth embodiments is provided, and the other configuration is the same, so the same functional parts Are given the same reference numerals and their description is omitted.

  The main part of the exhaust gas treatment apparatus 90 of the ninth embodiment has the same structure as that shown in FIG. 7, for example, and will be described with reference to FIG. As shown in FIG. 7, a partition plate 13 extending in the gas flow direction is provided in the middle of the exhaust gas duct 11, and the interior of the exhaust gas duct 11 is divided into two divided flow paths 11b and 11c. The two divided flow paths 11b and 11c are connected in parallel by providing the partition plate 13 in the exhaust gas duct 11, but the invention is not limited to this. For example, the exhaust gas duct 11 is branched into two ducts and joined again. You may make it form. A charging device 7 is provided in each of the two divided flow paths 11b and 11c.

  As the two charging devices 7, for example, a discharge electrode 7 c is provided at a substantially central portion of the divided flow paths 11 b and 11 c, and an inner wall forming the divided flow paths 11 b and 11 c and an inner wall of the partition plate are formed as counter electrodes. . The discharge electrode 7c is, for example, provided with a plurality of stages (for example, six stages) of linear electrode portions 7d extending in the gas flow direction, and connecting both ends of the electrode portions 7d to flow through the divided flow paths 11b and 11c. Are preferably charged substantially uniformly. The structure of the discharge electrode 7c is not particularly limited, but the mist can be charged substantially uniformly using another structure such as a mesh electrode. The two charging devices 7 may have either the same polarity or the opposite polarity, but it is preferable that the polarity of the charging be reversed.

When the charging polarities of the two charging devices are the same, the exhaust gas discharged from the wet desulfurization device 8 is divided into two while flowing through the exhaust gas duct 11, and flows into the two divided flow paths 11b and 11c, respectively. To do. The mist contained in the exhaust gas flowing into the two divided flow paths 11b and 11c is charged to the same polarity by each charging device 7, and then merges into the wet electrostatic precipitator 9 to be collected and removed. The At this time, since the SO ₃ mist is charged, for example, to a negative polarity, it is collected on the dust collecting electrode by the Coulomb force of the charge.

Further, as shown in FIG. 11, the particle diameter of the SO ₃ mist discharged from the charging device 7 is larger than that when no charge is applied (OFF), so that it is collected by the wet electrostatic precipitator 9. It becomes easier removal ratio of SO ₃ mist on the wet electrostatic precipitator 9 is increased.

Thus, since the removal rate of SO ₃ mist increases, the size of the wet electrostatic precipitator 9 can be reduced. As a result, in the wet electrostatic precipitator 9, when SO ₃ mist adheres to the dust collecting electrode, it reacts with moisture in the exhaust gas to form a strongly acidic aqueous solution. Therefore, the material used for the wet electrostatic precipitator 9 is made of a corrosion-resistant material. Although it is necessary to employ, the wet electrostatic precipitator 9 can be reduced in size, so that the equipment cost can be reduced. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

On the other hand, when the polarities of the charging of the two charging devices are opposite, the mists contained in the two exhaust gases are charged with opposite polarities by the two charging devices 7. When the two exhaust gases are merged, when mists having opposite polarities approach each other, they are attracted and aggregated by the mutual Coulomb force, resulting in a mist having a large particle diameter. For example, as shown in FIG. 11, the particle diameter of SO ₃ mist discharged from the charging device 7 is larger than when no charge is applied (OFF), and when charged with the same polarity. In comparison, the particle size of the SO ₃ mist is further increased. As a result, the SO ₃ mist is easily collected by the wet electrostatic precipitator 9, and the removal rate of the SO ₃ mist by the wet electrostatic precipitator 9 is increased. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

  In addition, although the exhaust gas flow path in which the charging device is provided is divided into two and the charging device is provided in each of the two divided flow paths, the exhaust gas flow path is divided into three or more without being limited thereto, You may make it provide a charging device in each division | segmentation flow path divided | segmented into 3 or more, respectively.

(10th Embodiment)
FIG. 12 is a view showing a part of the exhaust gas treatment apparatus of the tenth embodiment of the present invention. As shown in FIG. 12, the exhaust gas treatment apparatus 100 of the tenth embodiment removes NOx and dust contained in the gas from the combustion exhaust gas discharged from the two coal fired boilers 2, respectively, And the sulfur oxide is removed by one wet desulfurization apparatus 8. The same functional parts as those in the exhaust gas treatment apparatus of the above embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The exhaust gas treatment apparatus 100 of the tenth embodiment processes the combustion exhaust gas discharged from the two coal fired boilers 2, and the two first exhaust gas ducts into which the combustion exhaust gas discharged from the two coal fired boilers 2 flows. 61 and the second exhaust gas duct 62, and the first exhaust gas duct 61 and the second exhaust gas duct 62 are connected to each other so as to join the two exhaust gases and guide the gas. The first exhaust gas duct 61 and the second exhaust gas duct 62 are respectively provided with a denitration device 3, an air heater 4, a gas cooler 5, a dust collector 6 and the like in order from the upstream side of the exhaust gas. The third exhaust gas duct 63 is provided with a wet desulfurization device 8, a charging device 7, a wet electrostatic precipitator 9, an induction blower (not shown), a chimney 15, and the like.

  A partition plate 64 extending in the gas flow direction is provided in the middle of the third exhaust gas duct 63, and the interior of the third exhaust gas duct 63 is divided into two divided flow paths 63b and 63c. The two divided flow paths 63b and 63c are connected in parallel by providing a partition plate 64 in the third exhaust gas duct 63. However, the present invention is not limited to this. For example, the exhaust gas duct is branched into two ducts and merged again. You may make it form. A charging device 7 is provided in each of the two divided flow paths 63b and 63c. For example, the two charging devices 7 may be configured such that a discharge electrode is provided at substantially the center of the divided flow path, and the inner wall forming the divided flow path and the inner wall of the partition plate are used as counter electrodes. The two charging devices may have either the same polarity or the opposite polarity.

  When the charging polarities of the two charging devices 7 are the same, the mists contained in the exhaust gas discharged from the wet desulfurization device 8 are charged to the same polarity by the respective charging devices, and then merge to form the wet electricity It flows into the dust collector 9. For this reason, there exists an effect substantially the same as the exhaust gas processing apparatuses 70 and 80 of the said 7th and 8th embodiment.

On the other hand, when the charging polarities of the two charging devices 7 are opposite, the mists contained in the two exhaust gases are charged to the opposite polarities by the two charging devices 7. When the two exhaust gases are merged, when mists having opposite polarities approach each other, they are attracted and aggregated by the mutual Coulomb force, resulting in a mist having a large particle diameter. Mist having a large particle diameter flows into the wet electrostatic precipitator 9 together with the exhaust gas. Therefore, since tends to be trapped in the wet electrostatic precipitator 9, the removal rate of SO ₃ mist on the wet electrostatic precipitator 9 is increased. Therefore, SO ₃ contained in the exhaust gas can be more efficiently reduced without increasing the size of the wet electrostatic precipitator 9.

  In addition, although the case of the combustion exhaust gas from two coal fired boilers 2 was demonstrated, it is not limited to this, Even when the combustion exhaust gas from three or more coal fired boilers is processed, the exhaust gas treatment of the tenth embodiment It goes without saying that the device can be applied.

It is a figure showing the whole exhaust gas treatment device composition of a 1st embodiment of the present invention. It is a figure which shows the whole structure of the waste gas processing apparatus of 2nd Embodiment of this invention. It is a figure which shows the whole structure of the waste gas processing apparatus of 3rd Embodiment of this invention. It is a figure which shows the whole structure of the waste gas processing apparatus of 4th Embodiment of this invention. It is a figure which shows the principal part of the waste gas processing apparatus of 4th Embodiment of this invention. Is a diagram showing the particle size of the relationship between the SO ₃ mist. It is a figure which shows the principal part of the waste gas processing apparatus of 5th Embodiment of this invention, (a) is a schematic perspective view, (b) is a schematic plan view. It is a schematic perspective view which shows a part of structure of the waste gas processing apparatus of 6th Embodiment of this invention. It is a figure which shows the whole structure of the waste gas processing apparatus of 7th Embodiment of this invention. It is a figure which shows the whole structure of the waste gas processing apparatus of 8th Embodiment of this invention. It is a diagram showing a relationship SO ₃ removal rate in the wet electrostatic precipitator. It is a schematic perspective view which shows a part of structure of the waste gas processing apparatus of 10th Embodiment of this invention. Is a diagram showing a relationship between SO ₃ removal rate and the SO ₃ mist average particle size.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas treatment apparatus of 1st Embodiment 2 Boiler 6 Dust collector 7 Charging apparatus 8 Wet desulfurization apparatus 9 Wet electrostatic precipitator 10 Charge spray apparatus 11 Exhaust gas duct 12 Wet dust collector 20 Exhaust gas treatment apparatus 21 of 2nd Embodiment 21 Charge spray apparatus 30 Exhaust gas treatment apparatus according to the third embodiment 40 Exhaust gas treatment apparatus according to the fourth embodiment 41 Charge spray apparatus 50 Exhaust gas treatment apparatus according to the fifth embodiment 60 Exhaust gas treatment apparatus according to the sixth embodiment 61 First exhaust gas duct 62 Second exhaust gas duct 63 Third exhaust gas duct 70 Exhaust gas treatment device of the seventh embodiment 80 Exhaust gas treatment device of the eighth embodiment 90 Exhaust gas treatment device of the ninth embodiment 100 Exhaust gas treatment device of the tenth embodiment

Claims (9)

An air heater and gas cooler that recovers heat in the combustion exhaust gas of the boiler, a dust collector that collects dust in the exhaust gas whose heat has been recovered by the air heater and gas cooler, and sulfur in the exhaust gas discharged from the dust collector In an exhaust gas treatment apparatus comprising a wet desulfurization apparatus that removes oxide using a desulfurization agent slurry, and a wet electric dust collector that collects mist in exhaust gas discharged from the wet desulfurization apparatus,
An exhaust gas treatment apparatus, wherein a charge device for charging mist in the exhaust gas is provided in an exhaust gas flow path between the dust collector and the wet desulfurization device. A dust collector that collects dust in the combustion exhaust gas of a boiler, a wet dust collector that collects dust in the exhaust gas discharged from the dust collector, and sulfur oxides in the exhaust gas discharged from the wet dust collector In an exhaust gas treatment apparatus comprising a wet desulfurization device that removes using a desulfurization agent slurry, and a wet electric dust collector that collects mist in the exhaust gas discharged from the wet desulfurization device,
An exhaust gas treatment apparatus, wherein a charging device for charging mist in the exhaust gas is provided in an exhaust gas flow path between the wet dust collector and the wet desulfurization apparatus.
The exhaust gas flow path in which the charging device is provided has two divided flow paths that are connected in parallel and each provided with the charging device,
The exhaust gas treatment apparatus according to any one of claims 1 to 2, wherein the two charging devices provided in the two divided flow paths have a positive or negative charge polarity or the same polarity.   Two dust collectors are provided to individually collect the dust in the combustion exhaust gas of the two boilers, and two exhaust gas passages of the exhaust gas discharged from the two dust collectors are provided with the wet desulfurization. Each of the two exhaust gas channels is connected to one exhaust gas flow channel connected to the apparatus, and a charging device for charging mist in the exhaust gas is provided, and the two charging devices have a positive or negative charge polarity. The exhaust gas treatment device according to claim 1, wherein the exhaust gas treatment device is a waste gas treatment device.   The wet desulfurization apparatus is provided with a charge spray device that charges a part of a nozzle that sprays the desulfurization agent slurry, and the charge spray device charges a positive or negative charge different from the charge device. The exhaust gas treatment apparatus according to any one of claims 1 to 4. Dust collector that collects dust in combustion exhaust gas of boiler, wet desulfurizer that removes sulfur oxide in exhaust gas discharged from dust collector, and mist in exhaust gas discharged from wet desulfurizer In an exhaust gas treatment apparatus equipped with a wet electric dust collector that collects
An exhaust gas treatment apparatus, wherein a charging device for charging mist in the exhaust gas is provided in an exhaust gas flow path between the wet desulfurization apparatus and the wet electrostatic precipitator.   The exhaust gas flow path between the charging device and the wet electrostatic precipitator is provided with a charging spray device for spraying a liquid charged with positive or negative charges different from the charging device in the exhaust gas. The exhaust gas treatment apparatus described. The exhaust gas flow path in which the charging device is provided has two divided flow paths that are connected in parallel and each provided with the charging device,
The exhaust gas treatment apparatus according to claim 6 or 7, wherein the two charging devices provided in the two divided flow paths have a positive or negative charge polarity or the same polarity. The exhaust gas flow path in which the charging device is provided has two divided flow paths that are connected in parallel and each provided with the charging device,
The exhaust gas processing apparatus according to claim 6, wherein a charge spray device that charges positive or negative charges different from the charging device is provided in each of the two divided flow paths.

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