JP3322654B2 - Exhaust gas purification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust gas purifying apparatus for purifying exhaust gas containing nitrogen oxides, sulfur oxides, dust and the like.

[0002]

2. Description of the Related Art Conventionally, nitrogen oxides (hereinafter sometimes abbreviated as “NOx”) and sulfur oxides (hereinafter “SOx”) discharged from large-capacity boilers such as thermal power plants are known.
x ") is removed by a denitration device and a desulfurization device, respectively.

[0003] In the denitration apparatus, the exhaust gas is usually denitrated by an ammonia reduction method. In the ammonia reduction method, a high-temperature exhaust gas containing NOx is led to a denitration reactor equipped with a catalyst layer, and ammonia is sprayed to react the two with each other.
In this method, NOx is reduced by ammonia to decompose it into nitrogen and water vapor. In this method, a chemical reaction between ammonia and NOx occurs in the denitration reactor, and powdered nitrate may be generated and scattered. Therefore, it is necessary to provide an electric dust collector downstream of the denitration reactor. In addition, ammonia that has not caused a chemical reaction in the denitration reactor may flow out together with the processing gas, so that it is necessary to provide an ammonia outflow prevention device. As described above, in the conventional denitration apparatus,
There is a problem that the configuration is complicated.

In a desulfurization apparatus, desulfurization treatment of exhaust gas is usually performed by a wet lime gypsum method. In the wet lime gypsum method, SOx-containing exhaust gas is guided to an absorption tower, and an absorbent containing an alkali material is sprayed to absorb SOx, and air is blown to oxidize sulfurous acid in the absorbent, thereby producing sulfuric acid produced by an oxidation reaction. Is neutralized with limestone, and gypsum obtained by the neutralization reaction is collected. This method has a problem that the removal efficiency of SO ₃ mist, which is ultrafine coarse particles, is low, and it takes a long time to remove the SO ₃ mist. Further, there is a problem that gypsum which is a solid waste is generated.

Further, the conventional denitration and desulfurization treatments
Since the processes are performed based on different principles as described above, it is necessary to provide a processing device for each process, and there is a problem that the denitration and desulfurization processes cannot be performed simultaneously by one device. Several prior arts have been disclosed in order to solve such problems of the prior art. Japanese Patent Application Laid-Open No. H10-15346 discloses a moisture supply device that includes an exhaust gas passage for conducting exhaust gas, forms a discharge chamber with a pair of pulse discharge electrodes in the exhaust gas passage, and supplies mist or water vapor to the discharge chamber. And a denitration apparatus in which a discharge chamber is formed so as to be freely corona-discharged in the presence of moisture. The pair of pulse discharge electrodes includes a plurality of linear anodes and a disk-shaped cathode. In this prior art, the exhaust gas is denitrated by generating corona discharge between a pair of pulsed discharge electrodes.To efficiently perform the denitration process, one of the disc-shaped electrodes is moved along the flow direction of the exhaust gas. The electrode must be formed so as to extend over the entire discharge chamber, and there is a problem that the size of the electrode is increased.

[0006] Japanese Patent Application Laid-Open No. 8-10643 discloses SOx
Between the discharge electrode having needle-like thorns and the dust collecting electrode plate, while guiding the exhaust gas containing the gas to the wet-type electrostatic precipitator and allowing the alkali absorbing liquid film to flow uniformly over the entire surface of the plate-shaped dust collecting electrode plate. Discloses a desulfurization method in which a corona discharge is generated to perform a desulfurization treatment. In this prior art, the desulfurization treatment is performed by forming a liquid film on the entire surface of the precipitating electrode plate of the wet type electric precipitator, so that it is necessary to provide a circulating device for the absorbing solution, and the configuration becomes complicated. There is.

[0007]

In recent years, in order to protect a wide area environment such as in a tunnel of an automobile road and an intersection with heavy traffic, an apparatus for processing a large amount of exhaust gas containing low-concentration NOx, SOx, dust and the like. Development is required. Since this apparatus needs to treat a large amount of exhaust gas, it is necessary that the denitration efficiency, desulfurization efficiency, and dust removal efficiency are extremely good. According to the investigations of the present inventors, the above-mentioned JP-A-10-15346 and JP-A-8-10
In the prior art disclosed in Japanese Patent No. 643, the denitration efficiency and desulfurization efficiency are relatively low in addition to the problems described above,
There is a problem that it is not enough to be applied to the device for preserving the wide area environment.

It is an object of the present invention to solve the above-mentioned problems and to provide an exhaust gas purifying apparatus capable of efficiently purifying exhaust gas containing low-concentration NOx, SOx, dust and the like.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a processing container having an exhaust gas inlet and an exhaust gas outlet, in which water is partially stored and a discharge space is formed on the water surface. A container, a first electrode provided in the discharge space at an interval above the water surface, and a second electrode provided in the water or at the bottom of the water.
The first electrode is a second electrode between the electrode and the first and second electrodes.
A power source for generating a corona discharge in the discharge space by applying a voltage so as to have a higher potential than the electrode, wherein the first electrode is substantially horizontal along a flow direction of the exhaust gas introduced from the exhaust gas inlet. A flat base having a surface substantially parallel to the water surface, and a plurality of bases formed on the side end of the base along the longitudinal direction of the base and projecting outward from the side end in the width direction of the base. The projections are formed so as to move diagonally upward or diagonally downward from the virtual plane including the base as heading toward the tip, and the projections diagonally upward and the diagonally downward are formed in the longitudinal direction of the base. An exhaust gas purifying apparatus characterized in that the exhaust gas purifying apparatus is arranged alternately along the exhaust gas.

According to the present invention, water is partially stored inside the processing container, and a discharge space is formed above the water surface. A first electrode is provided in the discharge space, and a second electrode is provided below the water surface. The power supply applies a voltage so that the first electrode has a higher potential than the second electrode via the water surface between the first electrode and the second electrode, that is, sets the first electrode to positive, and applies a voltage. Generate corona discharge in space. When the first electrode is set to be positive, using an electrode having a specific shape, for example, a saw-shaped electrode as the first electrode, as compared with the case where the first electrode is set to be negative as shown in FIG. As a result, the discharge current can be increased. This also makes it possible to increase the ozone concentration in the discharge space as shown in FIG. 10 to be described later, and to increase the corona wind accompanying the corona discharge.

When exhaust gas containing substances to be removed such as NOx and SOx is introduced into the processing vessel, insoluble components in NOx and SOx are converted into soluble components by the oxidizing power of ozone. The converted soluble components are sprayed toward the water surface by corona wind together with the originally existing soluble components, so that the reaction between these soluble components and water is promoted, and the soluble components are efficiently dissolved in water and removed. Is done. Therefore, for example, FIG.
As shown in FIG. 3, the denitration efficiency can be improved. Further, since the dust can be charged by the corona discharge and attracted to the second electrode, the dust can be attached to the water surface and removed from the exhaust gas. As a result, substances to be removed such as NOx, SOx, and dust in the exhaust gas can be efficiently removed.
The present invention can be suitably applied to an apparatus for processing a large amount of exhaust gas containing x and dust (hereinafter, abbreviated as low-concentration exhaust gas).

[0012]

According to the present invention, the first electrode has a flat base and a saw-toothed projection, and the entire shape is formed in a sawtooth shape. When applied, the exhaust gas can be efficiently purified as described above.

The present invention also provides a processing container having an exhaust gas inlet and an exhaust gas outlet, wherein water is partially stored therein and a discharge space is formed on the water surface.
A first space provided in the discharge space at a distance above the water surface;
An electrode; a second electrode provided in water or on the bottom of the water;
A power source for generating a corona discharge in the discharge space by applying a voltage so that the first electrode has a higher potential than the second electrode, between the electrode and the second electrode, the first electrode comprising: A flat base extending substantially horizontally along the flow direction of the exhaust gas introduced from the exhaust gas inlet and having a surface substantially parallel to the water surface, and formed at the side end of the base along the longitudinal direction of the base, A plurality of projections projecting outward from the end in the width direction of the base in a tapered shape, wherein the projections are formed so as to be obliquely downwardly away from a virtual plane including the base toward the tip. It is an exhaust gas purification device.

According to the present invention, the projections of the first electrode are formed so as to be obliquely downward from the imaginary plane including the base toward the tip, so that all the projections are formed downward. And the distance from the water surface can be shortened. Therefore, the exhaust gas can be more efficiently purified.

Further, in the present invention, a water spray device for generating spray water is provided near the exhaust gas inlet of the processing container.

According to the present invention, since the spray water can be supplied to the discharge space from the water spray device, the soluble components of NOx and SOx converted by ozone can be dissolved in the spray water on the spot. In addition, dust can be removed by adhering to spray water. Therefore, the exhaust gas can be efficiently purified.

In the present invention, the second electrode extends along a flow direction of the exhaust gas introduced from the exhaust gas inlet.

According to the present invention, since the second electrode extends along the flow direction of the exhaust gas, corona discharge can be generated along the flow direction of the exhaust gas. Thereby, the stay time of the exhaust gas in the corona discharge region can be lengthened, and the exhaust gas can be efficiently purified.

[0020]

[0021]

[0022]

According to the present invention, there is provided an exhaust gas purifying apparatus described in one of the above, and an exhaust gas containing a substance to be removed is introduced into the processing vessel, and a gas is supplied between the first electrode and the second electrode. An exhaust gas purifying method, wherein a voltage is applied so that the first electrode has a higher potential than the second electrode to generate corona discharge in the discharge space.

According to the present invention, a voltage is applied between the first electrode having the sawtooth-shaped projections and the second electrode by setting the first electrode to a positive value, and a corona discharge is generated in the discharge space. Since the exhaust gas containing the substance to be removed is supplied in a state where the discharge has occurred, the exhaust gas can be reliably purified.

[0025]

[0026]

[0027]

FIG. 1 is a simplified perspective view showing the structure of an exhaust gas purifying apparatus 1 according to one embodiment of the present invention, and FIG. 2 is a front view as viewed from II-II in FIG. FIG. 3 is a side view as viewed from III-III in FIG. The exhaust gas purifying device 1 includes a processing container 3. The processing container 3
For example, it is made of a stainless steel plate, and water is partially stored inside, and the discharge space 4 is formed above the water surface. An exhaust gas inlet 5 is formed at one end of the processing container 3, and an exhaust gas inlet pipe 8 is connected to the exhaust gas inlet 5. At the other end of the processing container 3,
An exhaust gas outlet 6 is formed, and an exhaust gas discharge pipe 9 is connected to the exhaust gas outlet 6. A current plate 10 is provided adjacent to the exhaust gas inlet 6 side of the exhaust gas inlet 5, and a plurality of throttle holes 11 are formed in the current plate 10.

Exhaust gas containing at least one of substances to be removed, such as NOx, SOx and dust, flows into the processing vessel 3 from the exhaust gas introduction pipe 8,
Through the discharge space 4 and discharged from the exhaust gas discharge pipe 9. A pair of metal first electrodes 13 is provided above the discharge space 4 of the processing container 3 at an interval L1 above the water surface. The number of the first electrodes 13 is
The number is not limited to one pair, and may be one or three or more. The configuration of the first electrode 13 will be described later.

Below the first electrode 13 and below the water surface, a flat metal second electrode 14 is provided.
Are provided opposite to each other. In the present embodiment, the bottom plate of the processing container 3 forms the second electrode 14. by this,
Since the bottom plate of the processing container 3 and the second electrode 14 are shared, the apparatus can be simplified. The second electrode 14
It is not limited to the bottom plate of the processing vessel 3 and may be a flat electrode provided in the water of the storage water, and may be a flat electrode provided separately from the bottom plate of the processing vessel 3 on the bottom of the storage water. It may be an electrode.

A power supply 16 is provided near the processing container 3. The power supply 16 is, for example, a DC high-voltage power supply,
A high voltage is applied between the first electrode 13 and the second electrode 14 via the stored water to generate a corona discharge in the discharge space 4. The voltage is applied such that the potential of the first electrode 13 is higher than the potential of the second electrode 14, in other words, the polarity of the first electrode 13 is set to be positive.

The first and second electrodes 13 and 14 extend along the flow direction 17 of the exhaust gas. by this,
Since the corona discharge region can be formed along the flow direction 17 of the exhaust gas, the residence time of the exhaust gas in the corona discharge region can be lengthened, and the exhaust gas can be efficiently purified.

FIG. 4 is a simplified plan view showing the structure of the first electrode 13 shown in FIG. 1, FIG. 5 is a front view of FIG. 4, and FIG. 6 is a side view of FIG. The first electrode 13 includes a base 18 and a plurality of protrusions 19. Base 18
Has a substantially flat shape, and extends substantially horizontally along the flow direction 17 of the exhaust gas. The surface of the base 18 is substantially parallel to the water surface. The protrusion 19 is formed at one end of the base 18 along the longitudinal direction of the base 18, and protrudes outward from the side end in the width direction of the base 18. Protrusion 1
The shape of 9 is substantially triangular. The longitudinal direction of the base 18 is
It matches the flow direction 17 of the exhaust gas.

The projection 19 is formed so as to be obliquely upward or obliquely away from the imaginary plane 21 including the base 18 toward the distal end 20, and the projection which is obliquely upward and the projection which is obliquely downward is formed in the longitudinal direction of the base 18. Are alternately arranged along. The dimensions of the first electrode 13 are, for example, a plate thickness T: 0.64 mm and a pitch P of the projections 19: 2.54.
mm, the protrusion height h of the protrusion 19 from the side end of the base 18:
1.26 mm, the protrusion height s of the protrusion 19 from the surface of the base 18 is 0.24 mm, and the angle θ of the protrusion 19 is 55 °. Thus, since the projection 19 is formed in a sawtooth shape,
Hereinafter, the first electrode 13 may be referred to as a saw-shaped electrode. In the present embodiment, the protrusion 19 is provided on one side end of the base 18.
However, as shown in FIG. 7, it may be formed along both sides of the base 18 along the longitudinal direction of the base 18 as shown in FIG.

To purify the exhaust gas in the exhaust gas purifying apparatus 1, the saw-shaped electrode 13 is attached to the discharge space 4 at an interval above the water surface, and the exhaust gas contains at least one substance to be removed such as NOx, SOx or dust. Is introduced into the processing vessel 3, the polarity of the saw-shaped electrode 13 is set to be positive, a high DC voltage is applied between the saw-shaped electrode 13 and the second electrode 14 via a water surface, and the corona discharge This is done by generating Next, the reason why the voltage is applied with the polarity of the saw-shaped electrode 13 set to plus and the chemical reaction in the discharge space 4 will be described.

FIG. 8 is a graph showing the relationship between the discharge voltage and the discharge current in the discharge space using the polarity of the saw-shaped electrode 13 as a parameter, and FIG. 9 shows the relationship between the discharge voltage and the discharge current in the discharge space in the form of a needle. 4 is a graph showing the polarity of an electrode having a protrusion as a parameter. The measured values in FIG. 8 are obtained by attaching the sawtooth electrode 13 shown in FIGS. 4 to 6 to the discharge space 4 and applying a voltage between the sawtooth electrode 13 and the second electrode 14. The measurement conditions in FIG. 8 are as shown in Table 1.

[0036]

[Table 1]

The measured values shown in FIG. 9 are shown in FIGS. 1 to 3 by preparing an electrode (hereinafter, referred to as a “needle electrode”) in which a plurality of metal needle-like protrusions are evenly arranged on a metal flat plate. The needle electrode is attached to the exhaust gas purifying apparatus 1 instead of the first electrode 13, and the voltage is obtained by applying a voltage between the needle electrode and the second electrode 14. The measurement conditions in FIG. 9 are as shown in Table 2.

[0038]

[Table 2]

Reference numeral 23a in FIG. 8 indicates that the polarity of the saw-like electrode 13 is positive, reference numeral 23b indicates that the polarity of the saw-like electrode 13 is negative, and reference numeral 23 in FIG. 24a indicates that the polarity of the needle electrode 13 is positive, and reference numeral 24b indicates that the polarity of the needle electrode 13 is negative.

8 and 9, it can be seen from FIG. 8 that the discharge current increases as the discharge voltage increases for both the saw-shaped electrode 13 and the needle electrode.
Is set to be positive, the discharge current is larger than that of the saw-shaped electrode 13 is set to minus. In the case of the needle electrode, setting the needle electrode to minus in the high voltage region is more effective than setting the needle electrode to plus. It can be seen that the current is large. The reason why the polarity of the electrode at which the discharge current becomes large differs between the saw-like electrode and the needle electrode is probably due to the difference in the pitch of the protrusions and the electrode shape.

FIG. 10 is a graph showing the relationship between the discharge current of the saw-like electrode 13 and the ozone concentration in the discharge space 4. Reference numeral 25 in the figure indicates that the polarity of the saw-like electrode 13 is positive, and reference numeral 26 indicates that the polarity of the saw-like electrode 13 is negative.

From FIG. 10, it can be seen that the ozone concentration in the discharge space 4 increases as the discharge current increases, and that the polarity of the saw-shaped electrode 13 is set to be negative when the same discharge current is used. It can be seen that the ozone concentration in the discharge space 4 is higher than that in the discharge space 4. The reason why the ozone concentration in the discharge space 4 varies depending on the polarity of the saw-shaped electrode 13 even when the magnitude of the discharge current is the same is explained as follows.

When the polarity of the saw-like electrode 13 is set to minus and a high voltage is applied, the tip 2
Electrons are emitted from 0. Since the electrons have high mobility, a strong corona discharge is generated in a narrow region 22a near the tip of the projection 19 as shown in FIG. On the contrary,
When the polarity of the saw-like electrode 13 is set to plus and a high voltage is applied, ions are emitted from the tip 20 of the protrusion 19 of the saw-like electrode 13. Since ions have lower mobility than electrons, corona discharge is generated in a relatively large region 22b near the tip of the protrusion 19 as shown in FIG. Ozone is more likely to be generated when corona discharge occurs in the wide area 22b than when corona discharge occurs in the narrow area 22a.

As described above, when the polarity of the saw-shaped electrode 13 is set to be positive, the discharge current is larger than when the polarity is set to be negative, so that the amount of generated ozone is increased. When the discharge current is the same, the generation amount of ozone is larger when the polarity of the saw-shaped electrode 13 is set to be positive than when it is set to be negative. Therefore, setting the polarity of the saw-shaped electrode 13 to positive can greatly increase the amount of ozone generated as compared to setting the polarity to negative. Furthermore, when the amount of generated ozone is the same, the magnitude of the discharge current can be made smaller by setting the polarity of the saw-shaped electrode 13 to be positive than by setting the polarity to be negative. Can be generated.

FIG. 12 is a graph showing the relationship between the discharge voltage, the discharge current, and the denitration efficiency in the discharge space using the polarity of the saw-like electrode 13 as a parameter. The measurement values in FIG. 12 are obtained by using the same measuring apparatus as in FIG. 8 and introducing exhaust gas containing NOx and dust into the processing container 3. 12, the distance L1 between the saw-shaped electrode 13 and the water surface is 1
6 mm, and other measurement conditions are the same as in Table 1. FIG.
Reference numerals 27 and 28 in FIG. 2 respectively show the denitration efficiency and discharge current when the polarity of the saw-like electrode 13 is set to plus, and reference numerals 29 and 30 in FIG. The denitration efficiency and the current value when the value is set to minus are shown.

From FIG. 12, as the discharge voltage increases, the denitration efficiency increases regardless of the polarity of the saw-shaped electrode 13,
In addition, it can be seen that the discharge current increases, and that in a region where the discharge voltage is high, the denitration efficiency and the discharge current are higher when the polarity of the saw-like electrode 13 is set to be positive than when the polarity is set to be negative.

The denitration reaction in the discharge space 4 is caused by the following chemical reaction. In the discharge space 4, ozone is generated from oxygen in the air by corona discharge, and nitrogen monoxide (hereinafter, referred to as “NO”), which is a component of NOx in exhaust gas that is hardly dissolved in water, is oxidized by the ozone, In the reaction formula shown in Chemical Formula 1, NOx is converted to nitrogen dioxide (hereinafter referred to as “NO ₂ ”) which is a component easily soluble in water, and the converted soluble NO ₂ and the originally existing soluble NO ₂ are converted.
Is dissolved in water by the reaction formula shown in Chemical formula 2 and removed from the exhaust gas. In the corona discharge, since the ion wind accompanying the discharge occurs towards the water surface, with N0 ₂ soluble moves toward the water surface, to facilitate the dissolution of the water surface is ruffled N0 ₂ in water.

[0048]

## STR1 ## NO + O ₃ → NO ₂ + O ₂

[0049]

## STR2 ## _{3N0 2 + H 2 O → 2HNO} 3 + NO in such a denitration reactions, the discharge current, as shown in FIGS. 8 and 12 than when set to negative by setting the polarity of the sawtooth electrode 13 to the positive Since it becomes large, the ozone generation amount increases as shown in FIG. When the amount of generated ozone is increased, the reaction of Chemical Formula 1 is promoted and Chemical Formula 2
Reaction is promoted. Further, the corona wind becomes stronger as the discharge current increases, so that the reaction of Chemical Formula 2 is promoted. As a result, the denitration efficiency increases. As shown in FIG.
It is for this reason that the denitration efficiency can be increased by setting the polarity of the positive polarity to be higher than by setting the polarity to the negative polarity. Furthermore, since water vapor is generated in the discharge space 4 with an increase in the discharge current, it is considered that OH radicals are generated and a decomposition reaction of NO ₂ by the OH radicals is also occurring. NO ₂ is converted to N ₂ and O by the OH radical.
Decomposed into _two .

FIG. 13 is a graph showing the relationship between the discharge voltage in the discharge space and the denitration efficiency using the polarities of the saw-like electrode and the needle electrode as parameters. The measured values in FIG.
9 was obtained by introducing exhaust gas containing NOx and dust into the processing vessel 3 using the same measuring apparatus as that shown in FIG.
The distance L between the saw-shaped electrode 13 and the water surface among the measurement conditions shown in FIG.
1 is 16 mm, and other measurement conditions are the same as Tables 1 and 2. Reference numeral 27 in FIG. 13 indicates the denitration efficiency when the polarity of the saw-shaped electrode 13 is set to plus, and reference numeral 29 indicates the denitration efficiency when the polarity of the saw-shaped electrode 13 is set to minus. Reference numeral 31 indicates the denitration efficiency when the polarity of the needle electrode is set to minus, and reference numeral 32 indicates the denitration efficiency when the polarity of the needle electrode is set to plus.

From FIG. 13, it can be seen that the denitration efficiency increases as the discharge voltage increases, regardless of the polarity of the saw-shaped electrode 13 and the needle electrode. The denitration efficiency is higher in the region where the discharge voltage is higher than setting the polarity to minus, and setting the polarity of the needle electrode to minus is higher than setting the polarity of the needle electrode to plus regardless of the discharge voltage. It can be understood that the denitration efficiency is higher when the polarity of the saw-shaped electrode 13 is set to be positive than when the polarity of the needle electrode is set to be negative in a region where the discharge voltage is high. Each of the measurement results in FIG. 13 is due to an increase in the amount of ozone generated and an increase in corona wind as the discharge current increases, as in the case of FIG.

As described above, when the saw-shaped electrode 13 is attached to the discharge space 4, the polarity of the saw-shaped electrode 13 is set to plus, and the corona discharge is generated in the discharge space 4 to perform the denitration process, the needle electrode is discharged. The denitration efficiency can be higher than any of the method of attaching to the space 4 and performing the denitration processing by setting the polarity of the needle electrode to minus, and the method of performing the denitration treatment by setting the polarity of the saw-shaped electrode 13 to minus. . The reason why the polarity of the saw-like electrode 13 is set to be positive as described above is that the denitration efficiency can be increased as compared with other methods.

The principle of removing NOx in the exhaust gas is as follows.
It can also be applied to the removal of SOx in exhaust gas. That is, SO and SO ₂ in the exhaust gas are oxidized by ozone to be converted into SO ₃ which is a component easily dissolved in water, and SO ₃ in the exhaust gas can be removed by dissolving SO ₃ in water. The desulfurization reaction in the discharge space proceeds according to the reaction formulas (3) to (5).

[0054]

Embedded image SO + O ₃ → SO ₂ + O ₂

[0055]

Embedded image SO ₂ + O ₃ → SO ₃ + O ₂

[0056]

Embedded image attached to the _{SO 3 + H 2 O → H} 2 SO 4 denitration and the discharge space 4 a serrated electrode 13 also in such a desulfurization treatment, a corona the polarity of the sawtooth-shaped electrode 13 is set to positive By generating a discharge,
The discharge current can be increased as compared with the other methods described above, and the desulfurization efficiency can be increased.

Further, NOx and SO in the exhaust gas
The principle of removing x can be similarly applied to the removal of dioxin in exhaust gas. That is, dioxin in exhaust gas is oxidized by ozone and converted into a component easily soluble in water, and the component is dissolved in water to remove dioxin in exhaust gas.

As described above, in the denitration and desulfurization treatment, the saw-shaped electrode 13 is attached to the discharge space 4, the polarity of the saw-shaped electrode 13 is set to be positive, and a high voltage is applied between the electrodes.
This is performed by generating a corona discharge.
Such a configuration can also be applied to the removal of dust in exhaust gas. That is, the dust is charged by the corona discharge and is attracted to the second electrode, so that the dust can be attached to the water surface and removed. In this case, the dust removal rate can be increased by setting the polarity of the saw-shaped electrode 13 to a positive value, and the dust collected on the water surface and adhered to the water surface is less likely to be scattered again due to the viscosity of the water. Very good for the reasons.

As described above, in the present embodiment, the exhaust gas purifying apparatus 1 can efficiently remove NOx, SOx and dust in the exhaust gas. This is 1
This means that NOx, SOx and dust in the exhaust gas can be efficiently removed simultaneously by the two devices.
Therefore, the exhaust gas purifying apparatus 1 of the present embodiment can be suitably applied to an apparatus for processing a large amount of the low concentration exhaust gas.

FIG. 14 is a simplified plan view showing the structure of a first electrode 33 according to another embodiment of the present invention.
5 is a front view of FIG. 14, and FIG. 16 is a side view of FIG. The first electrode 33 of the present embodiment is similar to the first electrode 13 shown in FIGS. 4 to 6, and corresponding portions are denoted by the same reference numerals and description thereof will be omitted. It should be noted that all of the projections 19 are formed so as to be inclined obliquely downward from the imaginary plane 21 including the base 18 toward the tip 20. As a result, the distance between the tip 20 of the projection 19 and the water surface becomes shorter, so that the discharge current can be increased as a whole as compared with the first electrode 13. Therefore,
The first electrode 33 of the present embodiment can increase the ozone concentration in the discharge space 4 and generate a strong corona wind more than the first electrode 13, and further enhance the denitration efficiency, desulfurization efficiency, and dust removal rate. be able to.

FIG. 17 is a simplified front view showing the structure of an exhaust gas purifying apparatus 35 according to still another embodiment of the present invention. The exhaust gas purifying apparatus 35 of the present embodiment is similar to the exhaust gas purifying apparatus 1, and the corresponding parts are denoted by the same reference numerals and description thereof will be omitted. It should be noted that a water spray device 36 is provided near the exhaust gas inlet 5 of the processing container 3 of the exhaust gas purification device 35. The water spray device 36 is, for example, an ultrasonic mist generator, and supplies spray water (hereinafter, referred to as “mist”) into exhaust gas. Thereby, the exhaust gas purifying device 35 can dissolve and remove the soluble component originally converted from the insoluble component in the exhaust gas and the soluble component originally present in the mist in the discharge space 4 in the mist. Further, dust can be removed by attaching to the mist. Therefore, the exhaust gas purifying apparatus 35 of the present embodiment can remove NOx, SOx and dust in the exhaust gas more efficiently than the exhaust gas purifying apparatus 1, and is suitable for an apparatus that processes a large amount of the low-concentration exhaust gas. Can be applied.

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

As described above, in the present invention, although the electrode having the sawtooth-shaped protrusion is used as the first electrode 13,
An electrode having another configuration, for example, an electrode having a barbed wire mounted on a flat plate may be used. In this case, the same effect as that of the first electrode 13 having the saw-tooth projection can be obtained by using a barbed wire having a pitch as short as the saw-tooth projection.
Although a DC power supply is used as the power supply, other power supplies, for example, a pulse voltage generating power supply and an AC power supply may be used. The first and second electrodes 13 and 14 are configured to extend along the flow direction 17 of the exhaust gas, but may have other configurations.

[0070]

As described above, according to the first aspect of the present invention, since the voltage is applied so that the first electrode has a higher potential than the second electrode, the saw-shaped electrode is used as the first electrode. When used, the discharge current can be larger than when the first electrode is at a lower potential than the second electrode. Thereby, the ozone concentration in the discharge space can be increased, and the corona wind accompanying the corona discharge can be strengthened. When exhaust gas containing substances to be removed such as NOx and SOx is introduced into the processing vessel, the oxidizing power of ozone causes NOx
And the insoluble components in SOx are converted to soluble components. The converted soluble components are blown toward the water surface by the corona wind together with the originally existing soluble components, so that the reaction between these soluble components and water is promoted,
Soluble components are efficiently dissolved in water and removed. Further, since the dust can be charged by the corona discharge and attracted to the second electrode, the dust can be attached to the water surface and removed from the exhaust gas. As a result, substances to be removed such as NOx, SOx and dust in the exhaust gas can be efficiently removed, so that the present invention can be suitably applied to an apparatus for processing a large amount of low-concentration exhaust gas.

Further, according to the present invention, the first electrode has a flat base and a saw-toothed protrusion, and the entire shape is formed in a saw-tooth shape. When applied, the exhaust gas can be efficiently purified.

According to the second aspect of the present invention, the first
Since all the projections of the electrode are formed downward, the distance between the projections and the water surface can be shortened, and the exhaust gas can be more efficiently purified.

According to the third and fourth aspects of the present invention,
Since spray water can be supplied from the water spray device to the discharge space, NOx and SOx converted by ozone
The soluble components therein can be dissolved in the spray water in situ. In addition, dust can be removed by adhering to spray water. Therefore, the exhaust gas can be efficiently purified.

According to the fifth aspect of the present invention, the second
Since the electrodes extend along the flow direction of the exhaust gas, a corona discharge region can be formed along the flow direction of the exhaust gas. Thereby, the stay time of the exhaust gas in the corona discharge region can be lengthened, and the exhaust gas can be efficiently purified.

[0075]

According to the sixth aspect of the present invention, the first electrode is set to a positive voltage between the first electrode having the saw-toothed protrusion and the second electrode, and a voltage is applied to the discharge space. Discharge is generated, and the exhaust gas containing the substance to be removed in the state where the corona discharge is generated is supplied, so that the exhaust gas can be reliably purified.

[0077]

[Brief description of the drawings]

FIG. 1 is an exhaust gas purification apparatus 1 according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a simplified configuration of FIG.

FIG. 2 is a front view as viewed from II-II in FIG. 1;

FIG. 3 is a side view as viewed from III-III in FIG. 1;

FIG. 4 is a simplified plan view showing a configuration of a first electrode 13 shown in FIG.

FIG. 5 is a front view of FIG. 4;

FIG. 6 is a side view of FIG. 4;

FIG. 7 is a simplified plan view showing another configuration of the first electrode 13;

FIG. 8 is a graph showing a relationship between a discharge voltage and a discharge current in a discharge space, using the polarity of the saw-like electrode as a parameter.

FIG. 9 is a graph showing a relationship between a discharge voltage and a discharge current in a discharge space, using the polarity of an electrode having needle-like protrusions as a parameter.

FIG. 10 is a graph showing the relationship between the discharge current of the sawtooth electrode 13 and the ozone concentration in the discharge space 4.

FIG. 11 is a graph showing a relationship between the polarity of the saw-like electrode 13 and a corona discharge generation region.

FIG. 12 is a graph showing the relationship between discharge voltage, discharge current, and denitration efficiency in a discharge space, using the polarity of the saw-like electrode 13 as a parameter.

FIG. 13 is a graph showing the relationship between the discharge voltage in the discharge space and the denitration efficiency using the polarities of the saw-like electrode and the needle electrode as parameters.

FIG. 14 shows a first electrode 33 according to another embodiment of the present invention.
FIG. 2 is a plan view showing a simplified configuration of FIG.

FIG. 15 is a front view of FIG.

FIG. 16 is a side view of FIG. 14;

FIG. 17 is a simplified front view showing a configuration of an exhaust gas purifying apparatus 35 according to still another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1,35 Exhaust gas purifier 3 Processing vessel 4 Discharge space 5 Exhaust gas inlet 6 Exhaust gas outlet 8 Exhaust gas inlet pipe 9 Exhaust gas exhaust pipe 10 Rectifier plate 11 Restrictor hole 13 First electrode 14 Second electrode 16 Power supply 18 Base 19 Projection 36 Water Spraying equipment

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B03C 3/02 B01D 53/34 ZAB 3/16 133 3/41 (72) Inventor Tomi Fujii 8 Gakuen Higashicho, Nishi-ku, Kobe-shi, Hyogo Prefecture Chome 3 Kobe City National College of Technology Department of Electrical Engineering (56) References JP-A-8-108028 (JP, A) JP-A-8-10643 (JP, A) Jpn. (58) Field surveyed (Int. Cl. ⁷ , DB name) B03C 3/00-3/88

Claims (6)

(57) [Claims] 1. A processing container having an exhaust gas inlet and an exhaust gas outlet, in which water is partially stored and a discharge space is formed on the surface of the water, First spaced apart above
An electrode, a second electrode provided in water or on the bottom of the water, and a voltage applied between the first electrode and the second electrode so that the first electrode has a higher potential than the second electrode. A power source for generating corona discharge, wherein the first electrode extends substantially horizontally along the flow direction of the exhaust gas introduced from the exhaust gas inlet, and has a flat base having a surface substantially parallel to the water surface; A plurality of protrusions formed along the longitudinal direction of the base at the side end of the base, and protruding from the side end outward in the width direction of the base, the protrusion including a base toward the tip. An exhaust gas purifying apparatus formed so as to be obliquely upward or obliquely downward from a plane, and wherein projections which obliquely upwardly and projections which obliquely downwardly extend are alternately arranged along the longitudinal direction of the base. 2. A processing container having an exhaust gas inlet and an exhaust gas outlet, in which water is partially stored and a discharge space is formed on the surface of the water, First spaced apart above
An electrode, a second electrode provided in water or on the bottom of the water, and a voltage applied between the first electrode and the second electrode so that the first electrode has a higher potential than the second electrode. A power source for generating corona discharge, wherein the first electrode extends substantially horizontally along the flow direction of the exhaust gas introduced from the exhaust gas inlet, and has a flat base having a surface substantially parallel to the water surface; A plurality of protrusions formed along the longitudinal direction of the base at the side end of the base, and protruding from the side end outward in the width direction of the base, the protrusion including a base toward the tip. An exhaust gas purifying device formed so as to be obliquely downward from a plane. 3. In the vicinity of an exhaust gas inlet of the processing container,
3. The exhaust gas purifying apparatus according to claim 1, further comprising a water spray device for generating spray water. 4. A processing container having an exhaust gas inlet and an exhaust gas outlet, wherein a processing space in which water is partially stored and a discharge space is formed on the surface of the water is provided. First spaced apart above
An electrode, a second electrode provided in water or on the bottom of the water, and a voltage applied between the first electrode and the second electrode so that the first electrode has a higher potential than the second electrode. An exhaust gas purifying apparatus, comprising: a power supply for generating corona discharge; and a water spray device for generating spray water provided near an exhaust gas inlet of the processing container. 5. The exhaust gas purifying apparatus according to claim 1, wherein the second electrode extends along a flow direction of the exhaust gas introduced from the exhaust gas inlet. 6. An exhaust gas purifying apparatus according to claim 1, wherein an exhaust gas containing a substance to be removed is introduced into the processing container, and a first electrode and a second electrode are connected to each other. A method for purifying exhaust gas, comprising applying a voltage so that the first electrode has a higher potential than the second electrode, to generate a corona discharge in the discharge space.