WO2015005066A1 - Exhaust gas treatment method, and exhaust gas treatment device - Google Patents

Abstract

This exhaust gas treatment method is characterized by involving a step for supplying ozone and a first liquid, which is water or an aqueous solution, into an exhaust gas that contains NOx and that is 150°C or higher, and for generating a first mist, in which the water droplets of the first liquid are suspended, in the exhaust gas containing ozone gas. This exhaust gas treatment method may also involve a step for generating, in the exhaust gas that passed through the first mist, a second mist by spraying a second liquid which is a reducing agent aqueous solution.

Description

Exhaust gas treatment method and exhaust gas treatment apparatus

The present invention relates to an exhaust gas treatment method and an exhaust gas treatment apparatus.

Glass products such as glass bottles are manufactured by melting raw materials such as silica sand, soda ash, lime etc. and cullet made by crushing empty bottles with a burner etc. in a melting furnace (about 1500 ° C) and forming melted glass Be done. From the melting furnace that melts the glass, the flue gas containing the combustion exhaust gas from the burner and the component generated from the melted glass is discharged. The flue gas discharged from the melting furnace contains NOx and SOx, which are air pollutants, and these pollutants need to be removed from the flue gas before the flue gas is released to the atmosphere. In addition, since the combustion exhaust gas contains SOx derived from the glass raw material and catalyst poisoning components such as adhesive components, it is difficult to use the "selective catalyst reduction method" which is the conventional NOx treatment technology.

Further, as a method of removing NOx in combustion exhaust gas, there is known a method of reducing NO ₂ into nitrogen gas with a reducing agent after reacting NO gas with ozone gas and converting it into NO ₂ gas (for example, a patent) Reference 1).
In addition, when ozone gas exceeds 150 degreeC, the thermal decomposition amount will increase (for example, refer patent document 2).

JP-A-8-266868 Japanese Patent Application Laid-Open No. 55-1849

In the conventional method of removing NOx using ozone gas, when treating a large amount of flue gas at a high temperature, it is necessary to cool the flue gas with a large amount of water to a temperature of 150 ° C. or less in order to treat ozone gas. When the flue gas is treated with a large amount of water, the treated flue gas contains a large amount of water vapor, and there is a problem that the flue gas released to the atmosphere becomes white smoke. Further, when the flue gas is cooled with a large amount of water, there is a problem that equipment for circulating water and equipment for treating wastewater are required, and the treatment equipment becomes complicated and enlarged.
The present invention has been made in view of such circumstances, and provides an exhaust gas treatment method capable of ozone gas treatment of exhaust gas containing NOx and having a temperature of 150 ° C. or higher, and capable of simplifying treatment equipment.

The present invention supplies a first liquid, which is water or an aqueous solution, and ozone to an exhaust gas containing NOx at 150 ° C. or higher, and generates a first mist in which water droplets of the first liquid float in the exhaust gas containing ozone gas. Providing an exhaust gas treatment method including:

According to the present invention, the method includes the step of generating the first mist in which the water droplets of the first liquid, which is water or an aqueous solution, floats in the exhaust gas of 150 ° C. or higher. The resulting heat of vaporization can lower the temperature of the gas around the water droplet. For this reason, the temperature of the exhaust gas in the first mist can be lowered, and the thermal decomposition of the ozone gas in the first mist can be suppressed.
According to the present invention, since the water droplets of the first liquid float in the exhaust gas containing NOx and ozone gas in the first mist, the chemical reaction in which the NO ₂ gas is generated from the NO gas and the ozone gas in the gas phase of the first mist is It can be advanced. Therefore, the exhaust gas after passing through the first mist can be a gas having a low NO concentration and a high NO ₂ concentration.
While NO gas has the property of being difficult to dissolve in water, NO ₂ gas has the property of being easy to dissolve in water. Therefore, even if the exhaust gas having a low NO ₂ concentration and a high NO concentration is treated with the reducing agent aqueous solution, the NO gas is difficult to dissolve in water, so it is difficult to reduce NOx contained in the exhaust gas to N ₂ . On the other hand, when the exhaust gas having a low NO concentration and a high NO ₂ concentration is treated with the reducing agent aqueous solution, the NO ₂ gas is easily dissolved in water, so NOx contained in the exhaust gas can be reduced to N ₂ . That is, according to the present invention, the exhaust gas at 150 ° C. or higher can be transformed into a gas that is more likely to reduce NOx to N ₂ than the aqueous reducing agent solution treatment.
Further, according to the present invention, since NO can be converted to NO ₂ without using a catalyst, exhaust gas containing catalyst poisoning components such as SOx can be treated.
Further, according to the present invention, since exhaust gas of 150 ° C. or higher can be treated with ozone gas, it is possible to reduce the amount of water used for the treatment of the exhaust gas, thereby reducing the amount of water vapor contained in the exhaust gas released into the atmosphere. It is possible to reduce. As a result, it can be suppressed that the exhaust gas released to the atmosphere becomes white smoke.
Further, according to the present invention, since all the water contained in the first mist can be evaporated, the exhaust gas treatment apparatus can be configured to omit the water circulation device and the wastewater treatment facility, and the exhaust gas treatment apparatus can be simplified. can do.
Further, according to the present invention, the exhaust gas can be configured not to pass through the filler or the catalyst, and the exhaust gas processing apparatus can be easily maintained.

It is a schematic block diagram of the exhaust gas processing apparatus of one embodiment of the present invention. It is a schematic block diagram of the exhaust gas processing apparatus of one embodiment of the present invention. It is a schematic block diagram of the exhaust gas processing apparatus of one embodiment of the present invention. It is a schematic sectional drawing of the exhaust gas processing apparatus of one Embodiment of this invention. FIG. 5 is a schematic cross-sectional view of the sprayer in a range A enclosed by a broken line in FIG. 4; It is explanatory drawing of the chemical reaction in 1st mist. It is explanatory drawing of the chemical reaction in 2nd mist. It is explanatory drawing of the chemical reaction in 2nd mist. It is a schematic block diagram of the exhaust gas processing apparatus of one embodiment of the present invention. It is explanatory drawing of the chemical reaction in 1st mist. It is explanatory drawing of the chemical reaction in 1st mist. FIG. 2 is a schematic cross-sectional view of an exhaust gas processing device used in NOx removal experiment 1; It is a graph which shows the measurement result of NOx removal experiment 1. It is a graph which shows the temperature of the combustion exhaust gas measured by NOx removal experiment 2. It is a graph which shows the NOx concentration in the combustion exhaust gas measured by NOx removal experiment 2. It is a graph which shows the NO concentration in the combustion exhaust gas measured by NOx removal experiment 2. It is a graph which shows the NO removal rate and NOx removal rate in NOx removal experiment 2.

In the exhaust gas treatment method of the present invention, a first liquid, which is water or an aqueous solution, and ozone are supplied into an exhaust gas containing NOx at 150 ° C. or higher, and water droplets of the first liquid float in the exhaust gas containing ozone gas. And generating a signal.
In the present invention, mist refers to that in which a large number of water droplets are suspended in gas. Therefore, the mist includes a large number of floating water droplets (liquid phase) and a gas (gas phase) around the water droplets.

In the exhaust gas treatment method of the present invention, it is preferable to generate the first mist by spraying the first liquid into the exhaust gas, and to supply ozone gas to the generated first mist.
According to such a configuration, it is possible to generate the first mist in which the water droplets of the first liquid float in the exhaust gas containing the ozone gas. In addition, when the first liquid contains a reducing agent, the reducing agent can be suppressed from being consumed by the ozone gas.
In the exhaust gas treatment method of the present invention, it is preferable that the first liquid and the ozone gas be mixed and sprayed into the exhaust gas to generate a first mist.
According to such a configuration, it is possible to generate the first mist in which the water droplets of the first liquid float in the exhaust gas containing the ozone gas. Further, the probability that the ozone gas is exposed to high temperature can be reduced, and the thermal decomposition of the ozone gas can be suppressed.
In the exhaust gas treatment method of the present invention, it is preferable that all the water contained in the first mist evaporates in the process of the first mist flowing through the exhaust gas flow path.
According to such a configuration, it is not necessary to provide an apparatus for circulating water, and the exhaust gas processing apparatus can be simplified.

In the exhaust gas treatment method of the present invention, it is preferable to further include a step of causing the exhaust gas to pass through the first mist and spraying the second liquid which is a reducing agent aqueous solution into the exhaust gas after passing to generate a second mist. .
According to such a configuration, the exhaust gas having a low NO concentration and a high NO ₂ concentration due to the treatment with the first mist can be treated with the reducing agent aqueous solution in the second mist. Since the NO ₂ gas has the property of being easily dissolved in water, the NO ₂ gas can be reduced by the reducing agent in the second liquid contained in the second mist to generate the N ₂ gas. As a result, NOx in the exhaust gas can be removed.
In the exhaust gas treatment method of the present invention, the second liquid is preferably an aqueous solution containing sodium sulfite as a solute.
According to such a configuration, nitrogen gas and sodium sulfate can be generated by reacting NO ₂ with sodium sulfite.
In the exhaust gas treatment method of the present invention, it is preferable that all the water contained in the second mist evaporates in the process of flowing the second mist through the exhaust gas flow path.
According to such a configuration, it is not necessary to provide an apparatus for circulating water, and the exhaust gas processing apparatus can be simplified.

In the exhaust gas treatment method of the present invention, the exhaust gas preferably contains SOx, and the second liquid is preferably an alkaline aqueous solution.
According to such a configuration, the SO ₂ gas contained in the combustion exhaust gas can be dissolved in the second liquid to produce a reducing agent such as sulfite or sodium sulfite. This reducing agent can reduce the NO ₂ gas contained in the exhaust gas to generate N ₂ gas. As a result, NOx in the exhaust gas can be removed.
In the exhaust gas treatment method of the present invention, the second liquid is preferably an aqueous solution containing sodium hydroxide as a solute.
According to such a configuration, sodium sulfite can be produced from SO ₂ and sodium hydroxide.
In the exhaust gas treatment method of the present invention, the first liquid is preferably a reducing agent aqueous solution.
According to such a configuration, the NO ₂ gas generated from the NO gas and the ozone gas can be dissolved in the water droplets, and the NO ₂ can be reduced by the reducing agent to generate the N ₂ gas. As a result, NOx in the exhaust gas can be removed.

In the exhaust gas treatment method of the present invention, the exhaust gas preferably contains SOx, and the first liquid is preferably an alkaline aqueous solution.
According to such a configuration, the SO ₂ gas contained in the combustion exhaust gas can be dissolved in the first liquid to produce a reducing agent such as sulfite or sodium sulfite. In addition, NO ₂ gas generated from NO gas and ozone gas can be dissolved in water droplets, and this NO ₂ can be reduced by a reducing agent to generate N ₂ gas. As a result, NOx in the exhaust gas can be removed.
In the exhaust gas treatment method of the present invention, it is preferable to include the step of removing from the exhaust gas the fine particles produced from the reducing agent contained in the reducing agent aqueous solution and floating in the exhaust gas.
According to such a configuration, it is possible to suppress the release of particulates together with the exhaust gas into the atmosphere.
In the exhaust gas treatment method of the present invention, the exhaust gas is preferably a combustion exhaust gas generated from a melting furnace of glass.
According to such a configuration, it is possible to remove NOx in the flue gas containing the flue gas from the burner or the like and the component generated from the melted glass.

Further, according to the present invention, there is provided an exhaust gas flow path through which exhaust gas containing NO x at 150 ° C. flows, a first spray unit for spraying a first liquid which is water or an aqueous solution into the exhaust gas flow path, and And an ozone supply unit for supplying ozone, wherein the first spray unit and the ozone supply unit are provided such that a first mist in which water droplets of the first liquid float in the exhaust gas containing ozone gas is formed An apparatus is also provided.
According to the exhaust gas treating apparatus of the present invention, the exhaust gas flow path through which exhaust gas containing NOx is 150 ° C. or higher flows, and a first spray unit which sprays the first liquid, which is water or an aqueous solution, into the exhaust gas flow path Since the first spray unit is provided such that the first mist in which the water droplets of the first liquid float is formed in the exhaust gas, the water droplets contained in the first mist are vaporized by the evaporation of the water contained in the water droplets. The temperature of the surrounding gas can be lowered. For this reason, the temperature of the exhaust gas in the first mist can be lowered, and the thermal decomposition of the ozone gas in the first mist can be suppressed.
According to the exhaust gas treatment apparatus of the present invention, the exhaust gas flow path includes the ozone supply unit for supplying ozone, and the first spray unit and the ozone supply unit suspend water droplets of the first liquid in the exhaust gas containing ozone gas. Since the first mist is formed, the chemical reaction in which the NO ₂ gas is generated from the NO gas and the ozone gas in the gas phase of the first mist can be advanced. Therefore, by letting the exhaust gas pass through the first mist, the NO gas contained in the exhaust gas can be converted into the NO ₂ gas. As a result, the exhaust gas at 150 ° C. or higher can be transformed into a gas that is more likely to reduce NOx to N ₂ than the aqueous reducing agent solution treatment.

In the exhaust gas treatment apparatus of the present invention, the ozone supply unit is provided to supply ozone gas into a first mist formed by the first spray unit spraying the first liquid into the exhaust gas flow channel. Is preferred.
According to such a configuration, it is possible to generate the first mist in which the water droplets of the first liquid float in the exhaust gas containing the ozone gas. In addition, when the first liquid contains a reducing agent, the reducing agent can be suppressed from being consumed by the ozone gas.
In the exhaust gas treatment apparatus of the present invention, it is preferable that the first spray unit is provided to mix the first liquid and the ozone gas supplied from the ozone supply unit and spray the mixture into the exhaust gas flow path.
According to such a configuration, it is possible to generate the first mist in which the water droplets of the first liquid float in the exhaust gas containing the ozone gas. Further, the probability that the ozone gas is exposed to high temperature can be reduced, and the thermal decomposition of the ozone gas can be suppressed.

In the exhaust gas treatment apparatus of the present invention, the first liquid is preferably an alkaline aqueous solution or a reducing agent aqueous solution.
According to such a configuration, NO ₂ can be reduced in the liquid phase of the first mist to generate N ₂ gas. As a result, NOx in the exhaust gas can be removed.
In the exhaust gas treatment apparatus of the present invention, it is preferable that the first spray unit and the exhaust gas flow path be provided such that all the water contained in the first mist evaporates.
According to such a configuration, it is not necessary to provide an apparatus for circulating water, and the exhaust gas processing apparatus can be simplified.
The exhaust gas treatment apparatus of the present invention further includes a second spray unit for spraying a second liquid, which is an alkaline aqueous solution or a reducing agent aqueous solution, into the exhaust gas flow path through which the exhaust gas after passing through the first mist flows. preferable.
According to such a configuration, the exhaust gas having a low NO concentration and a high NO ₂ concentration due to the treatment with the first mist can be treated with the reducing agent aqueous solution in the second mist. Since the NO ₂ gas has the property of being easily dissolved in water, the NO ₂ gas can be reduced by the reducing agent in the second liquid contained in the second mist to generate the N ₂ gas. As a result, NOx in the exhaust gas can be removed.

In the exhaust gas treatment apparatus of the present invention, it is preferable that the second spray unit and the exhaust gas flow path be provided such that all the water contained in the second mist evaporates.
According to such a configuration, it is not necessary to provide an apparatus for circulating water, and the exhaust gas processing apparatus can be simplified.
In the exhaust gas treatment apparatus of the present invention, it is preferable to include a dust collector for removing particulates generated from the reducing agent contained in the reducing agent aqueous solution from the exhaust gas.
According to such a configuration, it is possible to suppress the release of particulates together with the exhaust gas into the atmosphere.

In the exhaust gas treatment apparatus of the present invention, the first spray unit has a spray nozzle having a first opening through which water droplets of the first liquid are ejected together with the first gas, and the ozone supply unit is provided around the spray nozzle. It is preferable that the first spray unit and the ozone supply unit constitute a sprayer.
According to such a configuration, it is possible to generate mist in which the fine water droplets of the first liquid float in the exhaust gas. Since the gas-liquid interface is wide in this mist, the exhaust gas can be efficiently brought into gas-liquid contact with the first liquid, and the exhaust gas can be treated with the solvent and the solute contained in the first liquid. In the mist, the temperature of the exhaust gas can be lowered by the heat of vaporization of the first liquid. It is also possible to treat the exhaust gas with the first gas. Furthermore, since the water droplets of the first liquid are ejected together with the first gas that functions as the spray diffusion gas, the spray angle of the first liquid can be broadened, and the region in which the mist is generated can be broadened. Further, the water droplets of the first liquid contained in the generated mist can be miniaturized. In addition, since the sprayer is provided around the spray nozzle and has a second opening through which the ozone-containing gas is ejected, the ozone-containing gas ejected into the exhaust gas from the second opening is immediately suspended by water droplets of the first liquid. Can flow efficiently into the mist. Therefore, the exhaust gas can be treated with the ozone-containing gas in the mist. In the mist, the temperature of the exhaust gas is lowered by the heat of vaporization of the first liquid, so that the thermal decomposition of ozone can be suppressed. Therefore, it becomes possible to treat high temperature exhaust gas with ozone which is easily thermally decomposed. Further, by causing the first liquid and the ozone-containing gas to be ejected from different openings, it is possible to suppress the reaction of the solvent or solute of the first liquid with the ozone-containing gas before the treatment. Further, by providing the first opening and the second opening in the same sprayer, the exhaust gas treatment apparatus can be simplified, and the manufacturing cost and operation cost of the exhaust gas treatment apparatus can be reduced.

In the exhaust gas treatment apparatus of the present invention, the sprayer is preferably disposed so that the water droplets of the first liquid, the first gas, and the ozone-containing gas are ejected in substantially the same direction as the exhaust gas flows.
According to such a configuration, the spraying direction of the sprayer and the flowing direction of the exhaust gas can be made to coincide with each other, and the region in which the mist is formed can be widened. Therefore, the exhaust gas can be brought into efficient gas-liquid contact with the first liquid. Further, the ozone-containing gas ejected from the second opening provided around the spray nozzle can efficiently flow into the mist in which the water droplets of the first liquid float on the flow of the exhaust gas. Therefore, the exhaust gas can be efficiently treated with the ozone-containing gas in the mist.

Hereinafter, an embodiment of the present invention will be described using the drawings. The configurations shown in the drawings and the following description are exemplifications, and the scope of the present invention is not limited to those shown in the drawings and the following description.

Exhaust Gas Treatment Method and Exhaust Gas Treatment Apparatus FIGS. 1 to 3 and 9 are schematic configuration diagrams of the exhaust gas treatment apparatus of the present embodiment. FIG. 4 is a schematic cross-sectional view of the exhaust gas processing device of the present embodiment, and FIG. 5 is a schematic cross-sectional view of the sprayer in a range A enclosed by a broken line in FIG.
In the exhaust gas treatment method of the present embodiment, the first liquid, which is water or an aqueous solution, and ozone are supplied into exhaust gas containing NOx at 150 ° C. or higher, and water droplets of the first liquid float in the exhaust gas containing ozone gas. It is characterized in that it includes the step of generating the mist 6.
Further, the exhaust gas treatment method of the present embodiment may include a step of spraying the second liquid 16 which is a reducing agent aqueous solution into the exhaust gas after passing through the first mist 6 to generate the second mist 7.
In the exhaust gas treatment method of the present embodiment, the exhaust gas flowing through the exhaust gas flow path 1 may be treated by a one-step treatment with the first mist 6, and the first treatment with the first mist 6 and the second treatment with the second mist 7 And the treatment by the first mist 6 and the treatment by the absorption tower 80 may be treated.
Furthermore, the exhaust gas treatment method of the present embodiment may include the step of removing the particulates 8 generated in the exhaust gas by the dust collector 17.

The exhaust gas processing apparatus 30 according to the present embodiment includes an exhaust gas flow path 1 through which exhaust gas containing NOx and 150 ° C. or higher flows, and a first spray unit 4 for spraying a first liquid, which is water or an aqueous solution, into the exhaust gas flow path 1; The exhaust gas flow path 1 includes an ozone supply unit 10 for supplying ozone, and the first spray unit 4 and the ozone supply unit 10 form a first mist 6 in which water droplets of the first liquid float in the exhaust gas containing ozone gas. It is characterized in that it is provided.
In addition, even if the exhaust gas processing device 30 of the present embodiment includes the second spray unit 5 that sprays the second liquid 16 that is an alkaline aqueous solution or a reducing agent aqueous solution in the exhaust gas after passing through the first mist 6. Good.
Further, the exhaust gas processing device 30 of the present embodiment includes the exhaust gas flow path 1 through which the exhaust gas flows, and the sprayer 50, and the sprayer 50 has a first opening 32 through which the water droplets 25 of the first liquid are ejected together with the first gas. The spray nozzle 40 and the second opening 33 provided around the spray nozzle 40 and from which the ozone-containing gas is jetted are provided. The sprayer 50 contains the water droplets 25 of the first liquid, the first gas and the ozone-containing gas in the exhaust gas. It may be a device at least a part of which is disposed in the exhaust gas flow path 1 so as to eject.
Hereinafter, the exhaust gas treatment method and the exhaust gas treatment device 30 of the present embodiment will be described.

1. Exhaust gas, exhaust gas flow path The exhaust gas is the gas to be treated in the exhaust gas treatment method and the exhaust gas treatment device 30 of the present embodiment, and is not particularly limited as long as it has a temperature of 150 ° C. or more and contains NOx. It may be the combustion exhaust gas discharged from the glass melting furnace 19 which melts the glass material 23 by the burner 20, or it may be the exhaust gas discharged from the melting furnace which electrically melts the glass material 23, from the combustion chamber of the boiler The exhaust gas may be exhaust gas emitted from an engine, may be exhaust gas emitted from a gas turbine, or may be exhaust gas emitted from an incinerator. Good.
When the exhaust gas is a combustion exhaust gas discharged from the glass melting furnace 19 which melts the glass raw material 23 by the burner 20, the glass melting furnace 19 uses the glass raw material 23 by the flame 21 of the burner 20 as shown in FIG. It can have a structure that holds the melted glass 22.
The exhaust gas flowing into the exhaust gas flow path 1 contains NOx such as NO. Further, the exhaust gas flowing into the exhaust gas flow path 1 may contain SOx such as SO ₂ . Note that NOx or SOx contained in the exhaust gas can be removed by the process performed when the exhaust gas flows through the exhaust gas flow path 1.
The exhaust gas has a temperature of 150 ° C. or more immediately before the portion (first processing region 2) at which the first mist 6 is generated at least in the exhaust gas flow channel 1.
The temperature of the exhaust gas can be, for example, 150 ° C. to 500 ° C., preferably 200 ° C. to 350 ° C., and more preferably 200 ° C. to 300 ° C. immediately before the first processing region 2. In addition, the exhaust gas after passing through the first processing region 2 is preferably 150 ° C. or more and 300 ° C. or less, preferably 150 ° C. or more and 250 ° C. or less. This can suppress the thermal decomposition of NO ₂ in the exhaust gas. Further, the temperature of the exhaust gas can be, for example, 130 ° C. or more and 240 ° C. or less at the stage of removing the particulates 8 in the exhaust gas by the dust collector 17.

The exhaust gas flow path 1 is a flow path which flows until the exhaust gas discharged from the glass melting furnace 19 or the like is released to the atmosphere. The exhaust gas flow path 1 may have a treatment chamber (including the first treatment area 2 or the second treatment area 3) for treating the exhaust gas with mist as shown in FIGS. In addition, the bottom of the treatment chamber may be sealed with water. In addition, the processing chamber can be a cavity which is not filled with the catalyst portion or the filler. In addition, the exhaust gas channel 1 can be provided so as not to have a portion filled with the catalyst portion or the filler.
Although the size of the exhaust gas flow path 1 is not particularly limited, for example, the diameter may be 50 cm or more and 4 m or less. Further, the flow velocity of the exhaust gas flowing through the exhaust gas flow channel 1 is not particularly limited, but can be, for example, 1 m / sec or more and 15 m / sec or less.
Moreover, the exhaust gas flow path 1 may have a waste heat boiler 62, an absorption tower 80, etc. like the exhaust gas processing device 30 shown in FIG.

2. Sprayer The sprayer 9 is a portion for spraying water or an aqueous solution into the exhaust gas. The spray unit 9 is the first spray unit 4 or the second spray unit 5. When water or an aqueous solution is sprayed into the exhaust gas flow path 1 by the spray unit 9, it is possible to generate mist in which a large number of water droplets float in the exhaust gas. The spray unit 9 is, for example, a spray nozzle. Further, the spray unit 9 may be a single fluid nozzle or a two fluid nozzle. When the spray unit 9 is a one-fluid nozzle, the spray unit 9 is provided to spray pressurized water or an aqueous solution into the exhaust gas. When the spray unit 9 is a two-fluid nozzle, the spray unit 9 can mix water or an aqueous solution with a gas and spray it into the exhaust gas. The gas mixed by the two-fluid nozzle may be, for example, air or ozone gas.

For example, as shown in FIGS. 1 and 2, the spray unit 9 can be provided with a treatment chamber in the exhaust gas flow path 1 so as to spray water or an aqueous solution into the treatment chamber. In addition, the spray unit 9 may be provided to spray water or an aqueous solution into the exhaust gas flow path 1 which is not a processing chamber.
Moreover, the spraying part 9 can be provided so that the process area | region which processes waste gas with the generated mist may be formed. Further, the spray unit 9 can be provided so that substantially all of the exhaust gas flowing through the exhaust gas flow path 1 flows through the processing region. For example, the diameter of the exhaust gas passage 1 may be reduced, or the amount of mist generated by the spray unit 9 may be increased. Further, a plurality of spray units 9 are provided on the side wall of the exhaust gas flow channel 1 so as to surround the exhaust gas flow channel 1, and each spray unit 9 is provided to spray water or an aqueous solution toward the central portion of the exhaust gas flow channel 1 It is also good. In addition, the spray unit 9 may be provided to spray water or an aqueous solution in the same direction as the exhaust gas of the exhaust gas flow path 1 flows. Furthermore, the spray unit 9 may be provided to spray water or an aqueous solution in a direction opposite to the direction in which the exhaust gas of the exhaust gas flow path 1 flows.
Further, the mist generated by the spray unit 9 moves along the flow of the exhaust gas.

The first spray unit 4 sprays the first liquid, which is water or an aqueous solution, into the exhaust gas at 150 ° C. or higher flowing through the exhaust gas flow path 1 and generates the first mist 6 in which the water droplets 25 float in the exhaust gas. Be As a result, the first processing region 2 in which the exhaust gas is treated with the first mist 6 can be formed in the exhaust gas flow path 1. The first processing region 2 can be formed in a cavity not filled with the catalyst portion or the filler.
The type of the first liquid is a two-stage process comprising the case where the exhaust gas is treated by the one-step treatment with the first mist 6, and the exhaust gas being the first treatment with the first mist 6 and the second treatment with the second mist It depends on the case of processing.
In the first mist 6 generated by the first spray unit 4, water droplets 25 float in the exhaust gas. The exhaust gas has a temperature of at least 150 ° C. immediately before at least the first treatment area 2. For this reason, in the first mist 6, water is vaporized on the surface of the water droplet 25 constituting the first mist 6, and the water droplet 25 gradually becomes smaller. Finally, the water droplets 25 disappear and the first mist 6 also disappears. Further, the temperature of the exhaust gas around the water droplet 25 is lowered by the heat of vaporization associated with the vaporization of water on the surface of the water droplet 25. Therefore, the temperature of the exhaust gas in the first mist 6 can be reduced.
Therefore, by generating the first mist 6, it is possible to partially form a region where the gas temperature is low in the exhaust gas flowing through the exhaust gas flow path 1.
The first spray unit 4 may also include a spray nozzle 40 included in a sprayer 50 described later.

The second spray unit 5 sprays the second liquid 16, which is an alkaline aqueous solution or a reducing agent aqueous solution, into the exhaust gas flow channel 1 and generates a second mist 7 in the exhaust gas flowing through the exhaust gas flow channel 1. As a result, it is possible to form the second processing region 3 in which the exhaust gas flowing through the exhaust gas flow path 1 is treated with the second mist 7. The second processing region 3 can be formed in a cavity not filled with the catalyst portion or the filler. The second spray unit 5 can be omitted when the exhaust gas is treated by the one-step process with the first mist 6.

When the exhaust gas is treated in two steps, the first spray unit 4 and the second spray unit 5 are provided so that the exhaust gas flowing in the exhaust gas flow path 1 flows in the second processing area 3 after flowing in the first processing area 2 Can. This makes it possible to treat the exhaust gas in two stages.
The first spray unit 4 and the second spray unit 5 may be provided so that the first processing area 2 and the second processing area 3 are formed in different processing chambers as in the exhaust gas processing apparatus 30 shown in FIG. Alternatively, as in the exhaust gas processing apparatus 30 shown in FIG. 2, the first processing area 2 and the second processing area 3 may be provided in the same processing chamber.
In addition, a dry state region may exist between the first treatment region 2 and the second treatment region 3 in the exhaust gas flow channel 1, and a part of the first treatment region 2 is the second treatment region 3. It may overlap with part of

3. Ozone Supply Unit The ozone supply unit 10 is a portion that supplies ozone into the exhaust gas flow path 1. Further, the first spray unit 4 and the ozone supply unit 10 are provided such that the first mist 6 in which the water droplets 25 of the first liquid float in the exhaust gas containing ozone gas is formed. As a result, it is possible to suppress the thermal decomposition of the ozone gas supplied into the exhaust gas flow path 1 by the ozone supply unit 10. In addition, ozone gas has the characteristic that the amount of thermal decomposition increases when it becomes 150 degreeC or more.
The ozone supply unit 10 can be provided to supply ozone gas into the first mist 6 formed by the first spray unit 4 spraying the first liquid into the exhaust gas flow path 1. As a result, in the first processing region 2, it is possible to form the first mist 6 in which the water droplets 25 of the first liquid float in the exhaust gas containing ozone gas. Further, in the first mist 6, the temperature of the exhaust gas is lowered due to the heat of vaporization of water contained in the water droplets 25, so that it is possible to suppress the thermal decomposition of the ozone gas supplied in the first mist 6.
The ozone supply unit 10 can be provided to supply ozone gas into the first mist 6 as in the exhaust gas processing device 30 shown in FIG. 1, for example.

Further, the ozone supply unit 10 is provided to supply the ozone gas to the first spray unit 4, and the first spray unit 4 mixes the first liquid and the ozone gas and sprays it into the exhaust gas flow path 1. It may be provided. As a result, in the first processing region 2, it is possible to form the first mist 6 in which the water droplets 25 of the first liquid float in the exhaust gas containing ozone gas. Further, in the first mist 6, the temperature of the exhaust gas is lowered by the heat of vaporization of water contained in the water droplets 25, so that the ozone gas in the first mist 6 can be prevented from being thermally decomposed.
In this case, as in the exhaust gas processing device 30 shown in FIG. 2, a two-fluid nozzle can be used for the first spray unit 4.
The ozone supply unit 10 may supply the ozone gas generated by the ozone generator 12 into the exhaust gas flow path 1. When the exhaust gas contains oxygen gas, the ozone gas supply unit 10 may generate ozone gas from the oxygen gas in the exhaust gas.
Further, the ozone supply unit 10 and the first spray unit 4 may be provided to spray ozone water (water in which ozone is dissolved) into the exhaust gas flow path 1. As a result, in the first processing region 2, it is possible to form the first mist 6 in which the water droplets 25 of the first liquid float in the exhaust gas containing ozone gas. In this case, the ozone supply unit 10 is a portion that supplies ozone water to the first spray unit 4.
In addition, the ozone supply unit 10 may include a second opening 33 included in a sprayer 50 described later.

4. Sprayer The sprayer 50 is provided with the spray nozzle 40 (1st spray part 4) which has the 1st opening 32 which the water droplet 25 of a 1st liquid ejects with 1st gas. Further, at least a part of the sprayer 50 is disposed in the exhaust gas flow path 1 so that the water droplets 25 of the first liquid and the first gas are ejected into the exhaust gas. For example, the sprayer 50 can be fixed to the exhaust gas flow path member 52 in a state where the spray nozzle 40 is inserted into the exhaust gas flow path 1 from the opening provided in the exhaust gas flow path member 52.
The material constituting the sprayer 50 can be, for example, stainless steel. In addition, preferably, SUS316L can be used. This can prevent the sprayer 50 from being corroded by the exhaust gas.
The spray nozzle 40 is a member having a first opening 32, and may have a mixing chamber in which the first liquid and the first gas are mixed.
Further, the spray nozzle 40 may be an internal mixing type two-fluid nozzle. As a result, the water droplets 25 of the first liquid to be sprayed can be miniaturized. In addition, the spray angle of the spray nozzle 40 can be widened. By this, the area | region in which mist is formed can be expanded and exhaust gas can be brought into gas-liquid contact efficiently. The spray angle of the spray nozzle 40 can be, for example, 120 degrees.

The first liquid is a liquid that treats the exhaust gas. When the first liquid is a solution, the exhaust gas may be treated with a solvent contained in the first liquid, or the exhaust gas may be treated with a solute contained in the first liquid. The first liquid is, for example, water, an aqueous solution, an alkaline aqueous solution, a reducing agent aqueous solution or the like. Thus, the exhaust gas can be treated with water or an aqueous solution, and the temperature of the exhaust gas can be reduced by the heat of vaporization of water. In addition, the exhaust gas can be treated with an alkali or a reducing agent.
The first gas is a gas for atomizing the first liquid. Further, the first gas may be a gas for treating an exhaust gas. The first gas is, for example, air or an ozone-containing gas. When an ozone-containing gas is used as the first gas, the exhaust gas can be oxidized with ozone.

A portion of the spray nozzle 40 provided with at least the first opening 32 is disposed in the exhaust gas flow path 1. As a result, it is possible to spray the water droplets 25 of the first liquid and the first gas into the exhaust gas flowing through the exhaust gas flow path 1 and generate the first mist 6 in which the water droplets 25 of the first liquid float in the exhaust gas. Can. Since the gas-liquid interface is wide in the first mist 6, the exhaust gas can be efficiently brought into gas-liquid contact with the first liquid, and the exhaust gas can be treated with the solvent and the solute contained in the first liquid. In the first mist 6, the temperature of the exhaust gas can be lowered by the heat of vaporization of the first liquid. It is also possible to treat the exhaust gas with the first gas.

The sprayer 50 may be disposed such that the water droplets 25 of the first liquid and the first gas are ejected in substantially the same direction as the flow direction of the exhaust gas. By this, the spraying direction of the sprayer 50 and the flowing direction of exhaust gas can be made to correspond, and the area | region in which the 1st mist 6 is formed can be expanded. Therefore, the exhaust gas can be brought into efficient gas-liquid contact with the first liquid. For example, the first opening 32 may be disposed downstream of the exhaust gas flow channel 1, and the sprayer 50 may be disposed such that the first liquid and the first gas are sprayed toward the downstream side of the exhaust gas flow channel 1.

The shape of the spray nozzle 40 can be, for example, cylindrical. In this case, the diameter of the spray nozzle 40 can be, for example, 5 mm or more and 100 mm or less.
Further, in this case, one end of the spray nozzle 40 can be connected to the first liquid flow channel 35 or the first gas flow channel 36, and the other end can have the first opening 32. The number of first openings 32 of the spray nozzle 40 may be one or more. Further, the end of the spray nozzle 40 provided with the first opening 32 may have a convex shape, and the first opening 32 may be provided on a convex slope. The shape of the first opening 32 may be circular.
The tip of the spray nozzle 40 is the tip of the end provided with the first opening 32, and may be a portion provided with the first opening 32, or may be a tip having a convex shape.

The sprayer 50 includes a second opening 33 (ozone supply unit 10) provided around the spray nozzle 40 and from which the ozone-containing gas is ejected. Further, at least a part of the sprayer 50 is disposed in the exhaust gas flow path 1 so that the ozone-containing gas is ejected into the exhaust gas. Further, a portion of the sprayer 50 provided with at least the second opening 33 is disposed in the exhaust gas flow path 1. As a result, the ozone-containing gas can be jetted into the exhaust gas flowing through the exhaust gas flow path 1, and the ozone-containing gas can flow into the first mist 6 in which the water droplets 25 of the first liquid float. Then, the exhaust gas can be treated with the ozone-containing gas in the first mist 6. In the first mist 6, since the temperature of the exhaust gas is lowered by the heat of vaporization of the first liquid, the thermal decomposition of the ozone-containing gas can be suppressed. Therefore, it becomes possible to treat the high temperature exhaust gas with the ozone containing gas which is easily thermally decomposed. Further, by causing the first liquid and the ozone-containing gas to be ejected from different openings, it is possible to suppress the reaction of the solvent or solute of the first liquid with the ozone-containing gas before the treatment.

The sprayer 50 can be arranged such that the ozone-containing gas spouts in substantially the same direction as the exhaust gas flows. Thus, the ozone-containing gas ejected from the second opening 33 provided around the spray nozzle 40 efficiently flows into the first mist 6 in which the water droplets 25 of the first liquid float on the flow of the exhaust gas. can do.

The second opening 33 may be provided such that the distance d2 from the tip of the spray nozzle 40 to the second opening 33 is longer than the distance d1 from the tip of the spray nozzle 40 to the first opening 32. By this, it can suppress that the spray angle of the spray nozzle 40 is restrict | limited by the 2nd opening 33, and can make the spray angle of the spray nozzle 40 wide. Therefore, the area | region in which the 1st mist 6 in which the water droplet 25 of a 1st liquid floats in waste gas is formed can be made wide.

5. Two-Stage Treatment with First Mist and Second Mist Here, the case where exhaust gas is treated by two-stage treatment composed of the first treatment with the first mist 6 and the second treatment with the second mist 7 will be described. The exhaust gas flowing through the exhaust gas flow path 1 can be treated in two stages by the exhaust gas processing device 30 shown in FIGS. In the two-stage treatment, the exhaust gas is first treated with the first mist 6 in the first treatment area 2, and the exhaust gas treated with the first mist 6 is treated with the second mist 7 in the second treatment area 3.

In the two-stage process, the first liquid can be water. In the first processing region 2, water (first liquid) and ozone are supplied into the exhaust gas at 150 ° C. or higher flowing through the exhaust gas flow path 1, and the first mist 6 in which the water droplets 25 float in the exhaust gas containing ozone gas and NOx gas Generate In this case, the first liquid functions as cooling water that lowers the temperature of the exhaust gas.
Further, all the water contained in the first mist 6 may evaporate in the process of the first mist 6 flowing through the exhaust gas flow path 1.

FIG. 6 is an explanatory view of a chemical reaction in the first mist 6. In the first mist 6, as shown in FIG. 6, water droplets 25 (liquid phase) float in the exhaust gas (gas phase) containing NOx gas and ozone gas. In addition, since the exhaust gas in the first mist 6 is lowered in temperature due to the heat of vaporization of water contained in the water droplets 25, the thermal decomposition of the ozone gas in the first mist 6 is suppressed.
Since the NOx gas and the ozone gas can coexist in the gas phase of the first mist 6, the reaction of oxidizing the NO gas contained in the exhaust gas into the NO ₂ gas by the ozone gas can be advanced.
For this reason, the exhaust gas after passing through the first processing region 2 where the first mist 6 is generated has a lower NO gas concentration and a higher NO ₂ gas concentration than the exhaust gas before passing through the first processing region 2 It becomes. Further, since the exhaust gas is cooled by the heat of vaporization of the first liquid in the first processing region 2, the temperature of the exhaust gas after passing through the first processing region 2 is lower than that of the exhaust gas before passing through the first processing region 2. It has fallen.

In the two-step process, the second liquid 16 can be an aqueous alkaline solution or an aqueous reductant solution. For example, the second liquid 16 can contain, as a solute, a substance such as sodium hydroxide or potassium hydroxide in which the aqueous solution exhibits alkalinity. The second liquid 16 can also contain a reducing agent such as sodium sulfite as a solute. In addition, the second liquid 16 can include both a substance whose aqueous solution exhibits alkalinity and a reducing agent.
The second liquid 16 has both a function as cooling water to lower the temperature of the exhaust gas and a function as a treatment liquid for removing NOx in the exhaust gas.
In the second treatment area 3, the second liquid 16 is sprayed into the exhaust gas after passing through the first treatment area 2, and the second mist 7 in which the water droplets 25 of the second liquid 16 float in the exhaust gas containing NO ₂ gas 7 Generate The water contained in the second mist 7 may all evaporate in the process of the second mist 7 flowing through the exhaust gas channel 1. Further, the second mist 7 can be generated by supplying the second liquid 16 stored in the second liquid tank 14 to the second spray unit 5 by the pump 15.
FIG. 7 is an explanatory view of a chemical reaction in the second mist 7 in the case where the second liquid 16 is an aqueous solution containing sodium sulfite which is a reducing agent. In the second mist 7, as shown in FIG. 7, water droplets 25 (liquid phase) containing sodium sulfite as a solute float in the exhaust gas (gas phase) containing NO ₂ gas.
The gas phase NO ₂ gas is considered to react with the H ₂ O of the water droplets 25 and the chemical reaction of the following formula (1) proceeds to move to the liquid phase as nitrous acid or nitric acid.
2NO ₂ + H ₂ O → HNO ₃ + HNO ₂ (1)
The liquid phase nitrous acid or nitric acid is considered to react with the reducing agent sodium sulfite, and the chemical reaction of the following formulas (2) and (3) proceeds.
2HNO ₃ + 5Na ₂ SO ₃ → N ₂ + 5Na ₂ SO ₄ + H ₂ O (2)
2HNO ₂ + 3Na ₂ SO ₃ → N ₂ + 3Na ₂ SO ₄ + H ₂ O (3)

During the second mist 7, when these chemical reactions proceed, it is possible to reduce the NOx contained in the exhaust gas to N _2, can be removed NOx contained in the exhaust gas.
The water droplets 25 contained in the second mist 7 gradually become smaller due to the vaporization of water, and it is considered that eventually the fine particles 8 of Na ₂ SO ₄ are left to disappear.
Therefore, the exhaust gas after passing through the second processing region 3 in which the second mist 7 is generated becomes a gas having low NO gas concentration and low NO ₂ gas concentration.
Further, since the exhaust gas is cooled by the heat of vaporization of the second liquid in the second processing region 3, the exhaust gas after passing through the second processing region 3 has a temperature which is higher than that of the exhaust gas before passing through the second processing region 3. It has fallen.

FIG. 8 is an explanatory view of a chemical reaction in the second mist 7 when the exhaust gas contains SO ₂ and the second liquid 16 contains sodium hydroxide. In the second mist 7, as shown in FIG. 8, water droplets 25 (liquid phase) containing sodium hydroxide as a solute float in the exhaust gas (gas phase) containing SO ₂ gas and NO ₂ gas.
The SO ₂ gas in the gas phase of the second mist 7 is considered to react with the NaOH in the water droplets 25, and the chemical reaction of the following formula (4) proceeds to move to the liquid phase as sodium sulfite.
SO ₂ +2 NaOH → Na ₂ SO ₃ + H ₂ O (4)
The gaseous phase NO ₂ gas of the second mist 7 is considered to react with the H ₂ O of the water droplets 25 to advance the chemical reaction of the formula (1) to move to the liquid phase as nitrous acid or nitric acid. The liquid phase nitrous acid or nitric acid is considered to react with sodium sulfite generated from SO ₂ to advance the chemical reaction of the above formulas (2) and (3).

During the second mist 7, when these chemical reactions proceed, it is possible to reduce the NOx contained in the exhaust gas to N _2, can be removed NOx contained in the exhaust gas.
The water droplets 25 contained in the second mist 7 gradually become smaller due to the vaporization of water, and it is considered that eventually the fine particles 8 of Na ₂ SO ₄ are left to disappear.
Therefore, the exhaust gas after passing through the second processing region 3 in which the second mist 7 is generated becomes a gas having low NO gas concentration and low NO ₂ gas concentration.
In addition, when the second liquid 16 contains both a substance in which the aqueous solution is alkaline and a reducing agent, NOx in the exhaust gas can be removed more effectively.

6. Two-Step Treatment with First Mist and Absorption Tower In the two-step treatment with the first mist 6 and the absorption tower 80, the absorption tower 80 can be provided downstream of the region in which the first mist 6 is generated. For example, the two-stage process by the first mist 6 and the absorption tower 80 can be performed by the exhaust gas processing device 30 shown in FIG. 3.
The treatment with the first mist 6 is the same as the above-mentioned “two-step treatment with the first mist and the second mist”, and thus the description thereof is omitted here.
In accordance with the two-stage process the absorption tower 80 and the first mist 6, the first step of the process according to the first mist 6, poorly soluble in water NO is converted into easily NO ₂ dissolved in water exhaust gas absorption tower 80 In the second stage of the absorption tower 80, NOx contained in the exhaust gas is removed.

The absorption tower 80 has an area filled with the filler 75, and the nozzle 77 sprays the third liquid from the top toward the filler 75. The sprayed third liquid flows in the filler 75 and accumulates in the liquid tank at the bottom of the absorber 80. The third liquid accumulated in the liquid tank is pumped by the circulation pump 68 and supplied to the nozzle 77. Thus, the absorber 80 is configured to circulate the third liquid.
The third liquid can be supplied from the chemical solution tank 70 to the liquid tank or the circulation channel 69 in the lower part of the absorption tower 80. Further, a pH meter 72 and an ORP meter 73 can be provided in the circulation channel 69 of the third liquid.
The region filled with the filler 75 can have, for example, a structure in which a plurality of metal plates having a plurality of holes are stacked. For the material of the metal plate, for example, stainless steel can be used. Further, a Raschig ring can also be used as the filler 75.
Further, an inlet for exhaust gas is provided in the lower part of the absorption tower 80, and an exhaust for the exhaust gas is provided in the upper part of the absorption tower 80. Therefore, the exhaust gas flows in the filler 75 from the lower part to the upper part of the absorber 80. Therefore, the exhaust gas and the third liquid can be brought into gas-liquid contact in the filler 75.

The third liquid can be a reducing agent aqueous solution containing a reducing agent such as sodium sulfite as a solute. As a result, the exhaust gas containing NO ₂ can be brought into gas-liquid contact with the aqueous solution of sodium sulfite in the region filled with the filler 75. When brought into gas-liquid contact, the NO ₂ gas contained in the exhaust gas reacts with H ₂ O, and the chemical reaction of the above-mentioned formula (1) proceeds, and it is thought that it moves to sodium sulfite aqueous solution as nitrous acid or nitric acid.
The nitrous acid or nitric acid transferred to the sodium sulfite aqueous solution is considered to react with the reducing agent sodium sulfite to advance the chemical reaction of the above formulas (2) and (3).
In the absorption tower 80, when these chemical reactions proceed, NOx contained in the exhaust gas can be reduced to N ₂ and NOx contained in the exhaust gas can be removed.
In addition, the third liquid can include a substance exhibiting alkalinity such as NaOH as a solute. This can prevent the exhaust gas component from being dissolved in the third liquid and the third liquid from becoming acidic.
Further, since the exhaust gas discharged from the absorption tower 80 contains a large amount of water, an eliminator 82 can be provided downstream of the absorption tower 80. Moreover, the dust collector 17, the fan 88, etc. can be provided in the downstream. The dust collector 17 may be, for example, an electric dust collector, a centrifugal dust collector, or a filtration dust collector.

7. One-Step Treatment with First Mist Here, the case where the exhaust gas is treated by the one-step treatment composed of the first treatment with the first mist 6 will be described. The exhaust gas flowing through the exhaust gas flow path 1 can be treated in one step by the exhaust gas processing device 30 shown in FIG.
In the one-step process, the first liquid 27 can be an alkaline aqueous solution or a reducing agent aqueous solution. For example, the first liquid 27 can contain, as a solute, a substance such as sodium hydroxide or potassium hydroxide in which an aqueous solution exhibits alkalinity. Also, the first liquid 27 can contain a reducing agent such as sodium sulfite as a solute. In addition, the first liquid 27 can contain both a substance whose aqueous solution exhibits alkalinity and a reducing agent. In this case, the first liquid 27 has both a function as cooling water to lower the temperature of the exhaust gas and a function as a treatment liquid for removing NOx in the exhaust gas.
In the first processing region 2, the alkaline aqueous solution or the reducing agent aqueous solution (the first liquid 27) and the ozone are supplied into the exhaust gas flowing in the exhaust gas flow path 1 at 150 ° C. or higher, and the first liquid is contained in the exhaust gas containing ozone gas and NOx gas. A water droplet 25 of 27 generates a first mist 6 in which the water droplet 25 floats. The water contained in the first mist 6 may be entirely evaporated in the process of the first mist 6 flowing through the exhaust gas flow path 1. The first mist 6 can be generated by supplying the first liquid 27 stored in the first liquid tank 26 to the first spray unit 4 by the pump 15.

FIG. 10 is an explanatory view of a chemical reaction in the first mist 6 in the case where the first liquid 27 is an aqueous solution containing sodium sulfite which is a reducing agent as a solute. In the first mist 6, as shown in FIG. 10, water droplets 25 (liquid phase) float in the exhaust gas (gas phase) containing the NOx gas and the ozone gas. In addition, since the exhaust gas in the first mist 6 is lowered in temperature due to the heat of vaporization of water contained in the water droplets 25, the thermal decomposition of the ozone gas in the first mist 6 is suppressed.
Since the NOx gas and the ozone gas can coexist in the gas phase of the first mist 6, it is possible to advance a reaction in which the NO gas contained in the exhaust gas is oxidized to the NO ₂ gas by the ozone gas.

The NO ₂ gas generated in the gas phase of the first mist 6 reacts with the H ₂ O of the water droplets 25 and the chemical reaction of the above formula (1) proceeds to move to the liquid phase as nitrous acid or nitric acid Conceivable.
The liquid phase nitrous acid or nitric acid is considered to react with the reducing agent sodium sulfite to advance the chemical reaction of the above formulas (2) and (3).
When these chemical reactions proceed in the first mist 6, NOx contained in the exhaust gas can be reduced to N _2, and NOx contained in the exhaust gas can be removed.
The water droplets 25 contained in the first mist 6 may gradually become smaller due to the vaporization of water, and may eventually disappear leaving fine particles 8 of Na ₂ SO ₄ .
For this reason, the exhaust gas after passing through the first processing region 2 in which the first mist 6 is generated becomes a gas having low NO gas concentration and low NO ₂ gas concentration. Further, since the exhaust gas is cooled by the heat of vaporization of the first liquid 27 in the first processing region 2, the exhaust gas after passing through the first processing region 2 has a temperature compared to the exhaust gas before passing through the first processing region 2. Is declining.

FIG. 11 is an explanatory view of a chemical reaction in the first mist 6 in the case where the exhaust gas contains SO ₂ and the first liquid 27 is an aqueous solution containing sodium hydroxide as a solute. In the first mist 6, as shown in FIG. 11, water droplets 25 (liquid phase) containing sodium hydroxide float in the exhaust gas (gas phase) containing ozone gas, SO ₂ gas and NO gas. In addition, since the exhaust gas in the first mist 6 is lowered in temperature due to the heat of vaporization of water contained in the water droplets 25, the thermal decomposition of the ozone gas in the first mist 6 is suppressed.
Since the NO gas and the ozone gas can coexist in the gas phase of the first mist 6, it is possible to advance the reaction of the NO gas contained in the exhaust gas being oxidized to the NO ₂ gas by the ozone gas.

The gas phase SO ₂ gas of the first mist 6 is considered to react with the NaOH of the water droplets 25 to advance the chemical reaction of the above formula (4) to move to the liquid phase as sodium sulfite.
It is believed that the NO ₂ gas generated by the oxidation of NO reacts with the H ₂ O of the water droplets 25 to advance the chemical reaction of the above formula (1) to move to the liquid phase as nitrous acid or nitric acid. The liquid phase nitrous acid or nitric acid is considered to react with sodium sulfite generated from SO ₂ to advance the chemical reaction of the above formulas (2) and (3).

When these chemical reactions proceed in the first mist 6, NOx contained in the exhaust gas can be reduced to N _2, and NOx contained in the exhaust gas can be removed.
The water droplets 25 contained in the first mist 6 may gradually become smaller due to the vaporization of water, and may eventually disappear leaving fine particles 8 of Na ₂ SO ₄ .
For this reason, the exhaust gas after passing through the first processing region 2 in which the first mist 6 is generated becomes a gas having low NO gas concentration and low NO ₂ gas concentration.
In addition, when the first liquid 27 is an aqueous solution containing both a substance exhibiting an alkalinity and a reducing agent, NOx in exhaust gas can be more effectively removed.

8. Dust Collector The dust collector 17 can be provided so that the exhaust gas treated by the one-step treatment or the two-step treatment flows in. As a result, the particulates 8 generated in the exhaust gas can be removed from the exhaust gas by the one-step or two-step treatment.
The dust collector 17 may be, for example, an electric dust collector, a centrifugal dust collector, or a filtration dust collector.

NOx removal experiment 1
FIG. 12 is a schematic cross-sectional view of the exhaust gas processing device (reaction tower) used in the NOx removal experiment 1. This reaction tower is a cylindrical cylinder made of SUS304 with an inner diameter of 54.9 mm and a height of 1000 mm, and the simulated exhaust gas to be treated flows from the lower portion of the reaction tower and is treated in the reaction tower and then discharged from the upper portion . The length from the gas inlet to the gas outlet was 600 mm. In order to reproduce high temperature exhaust gas (300 ° C), two heaters were attached to the top and bottom of the reactor wall. The simulated exhaust gas was used by setting the cylinder gas of 100 ppm NO concentration based on N ₂ to 10 L / min with a mass flow controller. The simulated exhaust gas was preheated in an electric tube furnace and then introduced into the reactor. In the reaction tower, the reducing agent (Na ₂ SO ₃ ) aqueous solution (spray solution) is sprayed from the top from the nozzle (first spray unit 4), and the simulated exhaust gas is cooled by the mist (first mist 6). The ozone-containing gas generated by the plasma generator is an ozone generator 12 (ozonizer) is injected into the first mist 6 of the reaction column was oxidizes NO simulated in the exhaust gas to NO _2. Also, NO ₂ reacts with the reducing agent (Na ₂ SO ₃ ) in the first mist 6 and is reduced to N ₂ . The treated gas was discharged from the upper outlet of the reactor. The reductant aqueous solution which did not evaporate was discharged from the outlet provided in the lower part of the reactor. Gas analysis was performed at the outlet of the reactor, and the concentration of NO, NOx and O ₂ was measured using a NOx meter (PG240 manufactured by Horiba, Ltd.).

The ozonizer used OZS-EPIII-05 manufactured by Masuda Research Institute, Inc. This ozonizer has a discharge voltage of about 5 to 8.6 kV, a maximum current of 0.4 A, a frequency of 9.6 kHz, and a maximum power consumption of 32 W. The ozone gas generation amount is 0 to 1.26 g / h, the ozone gas concentration is 0 to 95 g / m ³ , and the ozone gas flow rate is 0.1 to 1 L / min.
For the spray liquid, powdered Na ₂ SO ₃ was dissolved in water to prepare a chemical aqueous solution of a predetermined concentration. The chemical aqueous solution was stored in a beaker with an inner volume of 3 L, and the aqueous solution adjusted by the liquid feed pump and the flow meter was sent to the nozzle (first spray unit 4).

A pH / ORP meter (D-53 manufactured by Horiba, Ltd.) was placed in the beaker to measure the pH and ORP of the aqueous solution. The lower the value for ORP, the stronger the reducing power, and the higher the value, the more the reducing atmosphere changes to an oxidizing atmosphere. In a reducing atmosphere, NO ₂ is reduced to N ₂ by contact between Na ₂ SO ₃ and NO ₂ .
The liquid feed pump used was a diaphragm pump (NDP-5FST manufactured by Yamada Corporation), and the flow meter used was an area type (float type) flow meter (manufactured by KOFLOC) whose connection portion is made of SUS. As a nozzle, a single fluid nozzle (B1 / 4TT-SS + TX-SS1) manufactured by Spraying System Japan Ltd. was used. The flow rate is 65 mL / min under a pressure of 0.3 MPa, and the injection angle is 54 degrees.

An example of an experimental result is shown in FIG. The simulated exhaust gas introduced into the reaction tower was set at a flow rate of 10 L / min and an NO concentration of 100 ppm. First, without spraying the reducing agent aqueous solution, the simulated exhaust gas was passed through the reaction tower, and the gas temperature at the upper and lower portions of the reaction tower was set to be 300 ° C. The flow rate is set to 0.2 L / min, and the ozone concentration is set to 9 g / m ³ from 0 minutes to 30 minutes and 40 minutes to 50 minutes in FIG. 13 from 30 minutes to 40 minutes. Then, the ozone concentration was set to 15 g / m ³ . Also, in 50 to 60 minutes, the ozone gas-containing gas was not injected into the reaction tower.
The reducing agent aqueous solution was supplied from the nozzle (first spray unit 4) for 10 minutes to 60 minutes to generate a first mist 6. The supplied reducing agent aqueous solution was set to a flow rate of 40 mL / min, and the SO ₃ concentration was set to 10000 ppm. The first mist 6 is not generated from 0 minutes to 10 minutes.
It can be seen from FIG. 13 that, at 0 to 10 minutes, the temperature of the simulated exhaust gas is 300 ° C. and the concentration of NO is hardly decreased regardless of the fact that the ozone gas is injected into the reaction tower. This is considered to be because the injected ozone gas was thermally decomposed and was not used for the oxidation of NO.
It is considered that the thermal decomposition of the ozone gas in the first mist 6 is suppressed by cooling the gas in the first mist 6 by spraying the reducing agent aqueous solution in 10 minutes to 50 minutes. It is thought that the oxidation of NO by the ozone gas was efficiently performed in the first mist 6 by this. Further, it is found from FIG. 13 that the NOx concentration is also lowered by the NO ₂ reduction by the reducing agent in 10 minutes to 50 minutes.
The exhaust gas temperature in the upper part of the reaction tower in 10 minutes to 50 minutes was about 190.degree.

NOx removal experiment 2
An experiment was conducted to remove NOx contained in the combustion exhaust gas continuously discharged from the glass melting furnace 19 using the exhaust gas processing apparatus 30 as shown in FIG.
In the experiment, the combustion exhaust gas continuously discharged from the glass melting furnace 19 is treated by the waste heat boiler 62, the first mist 6 generated by the sprayer 50, the absorption tower 80, the eliminator 82, and the dust collector 17, and combustion after treatment The exhaust gas was released to the atmosphere. Further, at the measurement points A to E shown in FIG. 3, the temperature of the combustion exhaust gas being processed was measured. Further, the flue gas was sampled at measurement points D and E shown in FIG. 3, and the concentrations of NOx and NO contained in the flue gas were measured.

The experiment time was 9 hours, and the time for performing the ozone treatment with the first mist 6 and the time for not performing the ozone treatment with the first mist 6 were provided during the experiment. In the experiment, the treatment with the first mist 6 for 80 minutes was performed twice.
The amount of exhaust gas flowing through the exhaust gas flow path 1 was about 6700 Nm ³ / h. Further, an aqueous solution containing Na ₂ SO ₃ and NaOH was used for the reducing agent aqueous solution 67 circulated in the absorption tower 80, and the Na ₂ SO ₃ concentration was made 201 to 268 ppm. Further, NaOH was supplied to the aqueous reducing agent solution 67 so that the pH of the aqueous reducing agent solution 67 was about 8.
Further, the first mist 6 was generated by supplying water, air and an ozone-containing gas to the sprayer 50. The ozone-containing gas was generated by the ozone generator 12 that discharges air or oxygen gas, and was supplied to the sprayer 50. In the first treatment with the first mist 6, the ozone generator 12 generated 1255 g / h of ozone gas, and in the second treatment with the first mist 6, the ozone generator 12 generated 1436 g / h of ozone gas .

FIG. 14 shows the results of temperature measurement of the flue gas at the measurement points A to E. The temperature of the flue gas is about 450 ° C. at the outlet A of the glass melting furnace 19 and about 380 ° C. at the inlet B of the waste heat boiler 62 and about 180 ° C. at the outlet C of the waste heat boiler 62 It was about 160 ° C. in the previous D and about 50 ° C. at the outlet E of the eliminator 82.

FIG. 15 shows a time transition graph of the NOx concentration of the combustion exhaust gas at measurement points D and E every 20 minutes. Further, FIG. 16 shows a time transition graph of NO concentration of the combustion exhaust gas at the measurement points D and E every 20 minutes. Moreover, in FIG. 15, 16, the time which ozone-treated by the 1st mist 6 was shown by the arrow.
The NOx concentration shown in FIG. 15 and the NO concentration shown in FIG. 16 are converted values obtained by converting the measured values with the converted oxygen concentration being 15%. The converted value was calculated according to the provisions of the Air Pollution Control Law. Moreover, the converted values of NOx concentration and the converted values of NO concentration shown in FIGS. 15 and 16 are average values obtained from measurement data for 15 minutes excluding measurement data for 5 minutes at the time of combustion replacement from measurement data for 20 minutes. It is.
The NO x removal rate and NO removal rate calculated from the NO x concentration and NO concentration shown in FIGS. 15 and 16 are shown in FIG. The removal rate is a rate at which NOx or NO in the combustion exhaust gas is removed by both the ozone treatment with the first mist 6 and the reductant treatment with the absorption tower 80 or the reductant treatment with the absorption tower 80.

From FIGS. 15 to 17, in the time zone where the ozone treatment with the first mist 6 was not performed, the ozone treatment with the first mist 6 was performed while the NOx removal rate and the NO removal rate were about 0 to 7%. In the time zone, it was found that the NOx removal rate and the NO removal rate were about 14 to 39%.
From this, in the time zone where the ozone treatment was performed, the first mist 6 is generated in the combustion exhaust gas at about 160 ° C. by the atomizer 50, and the combustion exhaust gas is ozonated in the first mist 6 It is considered that the contained NO gas could be oxidized to the NO ₂ gas, and the generated NO ₂ gas could be removed from the combustion exhaust gas by the reducing agent treatment in the absorber 80.
In addition, since NO gas contained in combustion exhaust gas is not oxidized to NO ₂ gas in a time zone in which ozone treatment is not performed, it is considered that the NOx removal rate and the NO removal rate are low.

1: Exhaust gas flow path 2: First treatment area 3: Second treatment area 4: First spraying part 5: Second spraying part 6: First mist 7: Second mist 8: Fine particles 9: Spraying part 10: Ozone supply Part 12: Ozone generator 14: Second liquid tank 15: Pump 16: Second liquid 17: Dust collector 19: Glass melting furnace 20: Burner 21: Flame 22: Melted glass 23: Glass raw material 25: Water droplets 26: First Liquid tank 27: first liquid 30: exhaust gas treatment device 32: first opening 33: second opening 35: first liquid flow path 36: first gas flow path 37: ozone gas flow path 38: inner pipe 39: outer pipe 40 : Spray nozzle 41: Middle tube 42: Protective tube 43: Space 45: Third opening 46 Flange 47: Clearance 50: Sprayer 52: Exhaust gas flow path member 62: Waste heat boiler 67: Reductant aqueous solution 68: Circulation pump 69: Circulation flow path 70: Chemical solution tank 72: pH meter 73: ORP meter 75: Filler 77: Nozzle 80: Absorption tower 82: Eliminator 88: Fan 89: Chimney

Claims (12)

The exhaust gas treatment includes the steps of supplying a first liquid, which is water or an aqueous solution, and ozone into an exhaust gas containing NOx at 150 ° C. or higher, and generating a first mist in which water droplets of the first liquid float in the exhaust gas containing ozone gas. Method. The method according to claim 1, wherein the first liquid is an aqueous alkaline solution or an aqueous reducing agent solution or an aqueous alkaline solution containing a reducing agent as a solute. Further including a step of passing the exhaust gas into the first mist and spraying the second liquid into the exhaust gas after passing to generate a second mist,
The method according to claim 1, wherein the second liquid is an aqueous alkaline solution or an aqueous reducing agent solution or an aqueous alkaline solution containing a reducing agent as a solute. The method according to any one of claims 1 to 3, wherein the exhaust gas comprises SOx. 5. The method according to any one of claims 1 to 4, wherein the exhaust gas is an exhaust gas generated from a melting furnace of glass. An exhaust gas flow path through which exhaust gas containing NO x 150 ° C. flows, a first spray unit for spraying a first liquid which is water or an aqueous solution into the exhaust gas flow path, and ozone supply supplying ozone into the exhaust gas flow path Equipped with
The first spray unit and the ozone supply unit are provided such that a first mist in which water droplets of the first liquid float in the exhaust gas containing ozone gas is formed. The apparatus according to claim 6, wherein the ozone supply unit is provided to supply ozone gas into a first mist formed by the first spray unit spraying the first liquid into the exhaust gas flow channel. 7. The apparatus according to claim 6, wherein the first spray unit is provided to mix the first liquid and the ozone gas supplied from the ozone supply unit and spray the mixture into the exhaust gas flow path. The device according to any one of claims 6 to 8, wherein the first liquid is an alkaline aqueous solution or a reducing agent aqueous solution or an alkaline aqueous solution containing a reducing agent as a solute. The exhaust gas flow path through which the exhaust gas after passing through the first mist flows further includes a second spray unit for spraying a second liquid which is an alkaline aqueous solution or a reducing agent aqueous solution or an alkaline aqueous solution containing a reducing agent as a solute Item 9. The apparatus according to any one of Items 6 to 8. The first spray unit has a spray nozzle having a first opening from which water droplets of the first liquid are ejected together with the first gas,
The ozone supply unit has a second opening provided around the spray nozzle and from which the ozone-containing gas is jetted.
The apparatus according to claim 6, wherein the first spray unit and the ozone supply unit constitute a sprayer. The apparatus according to claim 11, wherein the sprayer is arranged to eject the water droplets of the first liquid, the first gas, and the ozone-containing gas in substantially the same direction as the flow direction of the exhaust gas.

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