JP2002204823A - Method and device for cleaning gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To synergetically improve the removing ratio of hazardous components in the case of cleansing a process gas containing the hazardous components by a corona discharge and a ultraviolet ray irradiation. SOLUTION: Corona discharge is performed by applying voltage between two electrodes 4 and 5 arranged in the process gas. One electrode 5 of the two electrodes 4 and 5 generating oxygen radical by the corona discharge is irradiated with the ultraviolet rays by an ultraviolet lamp 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing gas such as air,
The present invention relates to a method for purifying a harmful component such as an odor contained therein by using corona discharge between two electrodes and irradiation with ultraviolet rays, and a device therefor.

[0002]

2. Description of the Related Art JP-A-7-19468 as prior art
No. 4 and JP-A-8-238441 describe the use of corona discharge between two electrodes and irradiation of ultraviolet rays for purifying a gas such as air.

[0003] In the former, a harmful component in a processing gas is first decomposed by irradiating ultraviolet rays by providing an ultraviolet irradiation section on the upstream side of the gas flow and a corona discharge section on the downstream side. Next, purification is performed by decomposing by corona discharge on the downstream side.

On the other hand, in the latter, a corona discharge portion is provided on the upstream side in the gas flow and an ultraviolet irradiation portion is provided on the downstream side, so that harmful components in the gas are firstly decomposed by corona discharge. Next, it is decomposed and purified by irradiation of ultraviolet rays on the downstream side.

[0005]

By the way, the decomposition of the harmful component by the corona discharge is performed by applying a high voltage between the two electrodes to generate a turbulent state of ion wind to generate ozone. At the same time, oxygen radicals (free radicals) are generated around one of the electrodes, and the ozone and the radicals decompose harmful components.

However, the above-described prior art gas purification method has a configuration in which an ultraviolet irradiation section and a corona discharge section using two electrodes are arranged in series along the flow direction of the processing gas. As a result, the removal rate of harmful components by this method can only be obtained as the sum of the removal rate by irradiation with ultraviolet light and the removal rate by corona discharge, and there is a problem that the removal rate cannot be made higher than this sum. Was.

According to the present invention, oxygen radicals generated around one of the two electrodes are eliminated in a very short time. However, as will be described in detail below, the radicals generate oxygen radicals. By irradiating one electrode with ultraviolet light, it can be more activated,
Focusing on the fact that the service life can be extended, taking advantage of this fact, it is a technical issue to make the removal rate of harmful components higher than the sum of the removal rate by ultraviolet rays and the removal rate by corona discharge. Things.

[0008]

In order to attain this technical object, a purification method according to the present invention comprises the steps of applying a voltage between two electrodes disposed in a processing gas. And a corona discharge is performed, and one of the two electrodes, on which oxygen radicals are generated by the corona discharge, is irradiated with ultraviolet rays. "

According to a third aspect of the present invention, there is provided a purifying apparatus comprising the steps of: "arranging two electrodes for corona discharge in a processing gas, and forming a radical of oxygen by corona discharge among the two electrodes. An ultraviolet lamp for irradiating one of the electrodes with ultraviolet rays with ultraviolet light is disposed adjacent to the one of the electrodes. "

Further, according to the purifying apparatus of the present invention, the two electrodes for performing corona discharge are placed in a container in which the processing gas flows in from one end and flows out from the other end. Disposed so as to extend in the flow direction of the processing gas, and a straight-tube ultraviolet lamp extends along and adjacent to one of the two electrodes where oxygen radicals are generated by corona discharge. It is characterized in that it is arranged as described above. "

[0011] Still further, according to a fifth aspect of the present invention, in the fourth aspect, the cross section of the container is triangular, and the one electrode extending in the flow direction of the processing gas is provided at one corner of the triangle. And while disposing a straight tube ultraviolet lamp, the other electrode is a flat plate or a curved plate, and the other electrode is placed on one side of the respective sides of the triangle facing the one electrode. , And extending in the flow direction of the processing gas. "

[0012] In addition, claim 6 is that, of the two electrodes for corona discharge, one of the two electrodes excluding one electrode on which oxygen radicals are generated by corona discharge is formed in a cylindrical shape. The processing gas is configured to flow in the axial direction in the inside of the shape, and the one electrode and the straight tube-shaped ultraviolet lamp adjacent to the one electrode are axially extended at a center or a substantially central portion in the cylindrical shape. It is characterized by having been arranged in "."

[0013]

Next, an embodiment of the present invention will be described.

FIG. 1 and FIG. 2 show a first embodiment.

In the first embodiment, for example, a pipe-shaped container 1 having a circular section with an inner diameter d of 38 mm made of a non-conductive material such as glass is prepared. A gas inlet 2 is provided, and a gas outlet 3 is provided at an upper end.
The processing gas is configured to flow axially in the pipe-like container 1 upward from below.

Inside the pipe-shaped container 1, a flat plate-shaped anode electrode 4 made of a stainless steel plate and having a width W of about 25 mm is placed in the axial direction of the container 1, that is, the processing gas in the container 1. And a cathode electrode 5 made of a stainless steel wire having a wire diameter of 0.5 mm.
That is, they are disposed so as to extend in the flow direction of the processing gas in the container 1.

By connecting one cathode electrode 5 of the two electrodes 4 and 5 to the anode side of the DC power supply circuit 6 and connecting the other anode electrode 4 to the cathode side of the DC power supply circuit 6, , 5, a negative corona discharge from the cathode electrode 5 to the anode electrode 4 is performed by applying a high DC voltage.

Further, inside the pipe-shaped container, a 0.3 A, 12 V, ie, 3.6 watt, straight tubular ultraviolet lamp 7 having a diameter of 6 mm for emitting ultraviolet light having a main wavelength of 253.7 nm is provided with the cathode. It is arranged adjacent to and parallel to the electrode 5, that is, so as to extend in the flow direction of the processing gas in the container 1.

Reference numeral 8 denotes a power supply for the ultraviolet lamp 7. Further, the cathode electrode 5 made of the wire is held in tension by a spring 9.

In this case, portions of the cathode electrode 5 corresponding to the upper and lower ends 4a, 4b of the anode electrode 4 are covered with insulating films 10, 11, and the two insulating films 10, 10 of the cathode electrode 5 are covered. By exposing only a portion having a length L of about 100 mm between the anode electrodes 4 to the anode electrode 4, the length L can be reduced without causing spark discharge at the upper and lower ends 4a and 4b of the anode electrode 4. It was configured to perform corona discharge only in the portion.

It should be noted that the configuration in which the corona discharge is performed only in the portion having the length L is as described above, except that the portion having the length L is left on the cathode electrode 5 as described above.
Instead of forming the insulating film, an insulating film may be formed on the upper and lower ends 4a and 4b of the anode electrode 4 except for a portion having a length L for corona discharge.

Then, 20p is placed in the pipe-shaped container 1.
(1). A processing gas (air) containing acetaldehyde having a flow rate of 1000 pm per minute flows through the gas inlet 2 at a flow rate of 1000 cc per minute and then continuously flows out of the gas outlet 3. A case where corona discharge is performed by applying a voltage of about 8 to 8.5 kV at 0.1 mA between the electrodes 4 and 5 (this is referred to as corona discharge I). (2). When a voltage of about 8 to 10 kV is applied at 0.2 mA between the electrodes 4 and 5 to perform corona discharge (this
Corona discharge II). (3). When a voltage of about 8 to 10 kV is applied at 0.3 mA between the electrodes 4 and 5 to perform corona discharge (this
Corona discharge III). (Four). When a voltage of about 10 to 11 kV is applied at 0.4 mA between the electrodes 4 and 5 to perform corona discharge (this is referred to as corona discharge IV). (Five). When a voltage of about 11 to 12.5 kV is applied at 0.6 mA between the electrodes 4 and 5 to perform corona discharge (this is referred to as corona discharge V). With respect to the above, the result of performing an experiment for obtaining the acetaldehyde removal rate by measuring the concentration of acetaldehyde at the gas inlet 2 and the gas outlet 3 is as follows:
As shown in FIG.

That is, the removal rate in the state where only the 3.6-watt tubular ultraviolet lamp 7 is turned on without performing the corona discharge described above is as shown by the dashed line A. The removal rate when only the above-described corona discharges were performed in a state where the light emitting device 7 was turned off was as shown by a dotted line B, and the sum of the dashed line A and the dashed line B was as shown by a two-dot chain line C. .

On the other hand, under the condition that each corona discharge was performed, the 3.6 watt ultraviolet lamp 7 was used.
By lighting, the removal rate of acetaldehyde is
A solid line D is shown, which is much higher than the two-dot chain line C in which the case where only the ultraviolet lamp 7 is turned on and the case where only corona discharge is performed.

In particular, the 3.6 watt ultraviolet lamp 7
As shown in FIG. 4 which is a modified example of the first embodiment, as shown in FIG. 4, two acetaldehyde removal ratios are provided on the left and right sides of the cathode electrode 5.
As shown by the dotted line, it is much higher than the two-dot chain line C 'which is the sum of the one-dot chain line A' when only the ultraviolet lamp 7 is used and the dotted line B 'when only corona discharge is used. It was possible to further improve the situation even more.

This is because the corona discharge between the two electrodes 4 and 5 causes the discharge and discharge in a region within an angle θ between dotted lines α1 and α2 connecting the cathode electrode 5 and the left and right ends 4c and 4d of the anode electrode 4. Ozone is generated by a reaction relating to oxygen, and the flow state becomes turbulent due to negative ion wind from the cathode electrode 5 toward the anode electrode 4, and acetaldehyde is decomposed by the ozone generated here, Around the cathode electrode 5 having a large electric field density, oxygen radicals are generated by the reaction between greatly accelerated electrons and oxygen molecules, and acetaldehyde is also decomposed by the oxygen radicals. Oxygen radicals generated around are irradiated with ultraviolet rays from an ultraviolet lamp 7, Ri In addition to activating, and so the time until the radicals are lost is prolonged, since the radical can long life, and as it can synergistically enhance the removal rate of acetaldehyde, moreover,
The activation of the radical and the extension of the life are performed by the ultraviolet lamp 7.
It is believed that increasing the wattage can further enhance the wattage.

It is to be noted that substantially the same result can be obtained when an ultraviolet lamp having a double wattage is used instead of using two ultraviolet lamps 7. 185 nm, 320 n
When the wavelength was set to m, 365 nm or 420 nm, the same result as in the case where the dominant wavelength was set to 253.7 nm could be obtained as described above.

In short, one of the two electrodes 4 and 5 for performing corona discharge is irradiated with ultraviolet light by an ultraviolet lamp 7 disposed adjacent to one of the cathode electrodes 5 where oxygen radicals are generated by corona discharge. By irradiating, the removal rate of acetaldehyde can be synergistically higher than the sum of the case of only corona discharge and the case of only ultraviolet irradiation.

As described above, in the pipe-shaped container 1,
Decomposition of acetaldehyde in the processing gas (air) is achieved by forming the anode electrode 4, the cathode electrode 5, and the ultraviolet lamp 7 so as to extend in the flow direction of the processing gas in the pipe-shaped container 1. However, the removal rate of acetaldehyde can be reduced, for example, by arranging a plurality of electrode pairs composed of two electrodes for corona discharge at appropriate intervals along the flow direction of the processing gas, or And the anode electrode 4, the cathode electrode 5, and the ultraviolet lamp 7 extend in the direction in which the processing gas flows. Thus, the flow resistance of the processing gas (air) can be reduced because the flow resistance can be reduced.

As another modified example of the first embodiment, the anode electrode 4 is replaced by the anode electrode 4 shown in FIGS.
As shown in FIG. 6, the present invention is not limited to a flat plate, but may be an arc-shaped curved plate having a radius R substantially at the center of the cathode electrode 5 as shown in FIG. Can be averaged. Thus, the anode electrode 4
Is also applicable to the case of a second embodiment described later.

By the way, in the above-mentioned apparatus, the angle θ between the dotted lines α1 and α2 connecting the cathode electrode 5 and the left and right ends 4c and 4d of the anode electrode 4 is generated by the negative corona discharge at the electrodes 4 and 5. Mainly by the turbulent flow of ion wind
Since acetaldehyde is decomposed in the region within the angle θ, if the cross-sectional shape of the container 1 is round as shown in FIGS. The processing gas (air) flowing in the container 1 in the axial direction due to the larger cross-sectional area in the portion outside the region portion does not pass through the region portion within the angle θ but passes through the outside portion. , The acetaldehyde removal rate is reduced accordingly.

On the other hand, the present invention proposes a second embodiment shown in FIGS.

That is, in the second embodiment, the cross section of a pipe-shaped container 1 'having a gas inlet 2' at the lower end and a gas outlet 3 'at the upper end is circular as in the first embodiment. The anode electrode 4 formed in a strip shape from a stainless steel plate is disposed on one side of the triangle inside the triangle, while the anode electrode 4 is formed as a regular triangle or a triangle close to the triangle. Electrode 5 and a straight tubular ultraviolet lamp 7 adjacent thereto
Is disposed at one of the three corners of the triangle facing the anode electrode 4, and the other configuration is the same as that of the first embodiment.

With this configuration, the anode electrode 4 and the left and right end portions 4c, 4a of the anode electrode 4 in the cross-sectional area in the pipe-shaped container 1 'having a triangular cross-section.
d, the cross-sectional area in the portion outside the region within the angle θ between the dotted lines α1 and α2 can be made much smaller than when the cross section of the container is rounded,
Since the frequency of the processing gas (air) flowing in the container 1 'in the axial direction passing through the area of the angle θ increases, the removal rate of acetaldehyde is reduced by two ultraviolet fluorescent lamps as shown in FIG. Thus, the flow resistance of the processing gas can be improved to the extent that it is used without significantly increasing the flow resistance.

By the way, the above two embodiments are as follows.
In any case, the anode electrode 4 of the two electrodes 4 and 5 for corona discharge is formed as a strip-shaped flat plate or a curved plate, and this is disposed in the pipe-shaped container 1 so as to extend in the axial direction thereof. However, the present invention is not limited to this, and may be configured as in the third embodiment shown in FIGS. 9 and 10.

That is, a cylindrical anode electrode 4 'is formed so that the processing gas flows therein as shown by the arrow, and the center or substantially center of the cylindrical anode electrode 4 A cathode electrode 5 'extending in the vertical direction and at least one or a plurality of straight tubular ultraviolet lamps 7' extending in the axial direction are arranged adjacent to the cathode electrode 5 '. It is. In this case, the cylindrical anode electrode 4 'is a container in which the processing gas flows.

With this configuration, ionic wind is generated in all the regions in the cylindrical anode electrode 4, and all the processing gas flowing in the container 1 in the axial direction is converted into the region in which the ionic wind is generated. Since the gas can be reliably passed, the removal rate can be further improved without increasing the flow resistance of the processing gas.

As a modification of the third embodiment, as shown in FIGS. 11 and 12, one straight tube-shaped ultraviolet ray is placed at the center or substantially the center of the cylindrical anode electrode 4 ″. The lamp 7 "can be arranged so as to extend in the axial direction, and a plurality of cathode electrodes 5" extending in the axial direction can be arranged around the ultraviolet lamp 7 ".

Further, as a modification of the embodiment shown in FIGS. 11 and 12, as shown in FIG. 13, the cathode electrode 5a can be formed by winding a metal net into a cylindrical shape.

In each of the above embodiments, the corona discharge between the electrodes 4, 4 ', 4 ", 5, 5', 5" is performed.
One electrode 5, 5 ', 5 "to the other electrode 4, 4',
Although a positive corona discharge toward 4 ″ was performed, the present invention is not limited to this.
4 ', 4 ", 5, 5', and 5", the other electrode 4, 4 ', 4 "
A negative corona discharge toward 5 ', 5 "may be performed, or the two electrodes 4, 4', 4", 5, 5 ',
Needless to say, the present invention can be applied to a case in which negative and positive corona discharges are alternately performed by applying an AC power supply during 5 ″.

[0041]

As described above, according to the purifying method and the purifying apparatus according to the first and third aspects, the harmful components are synergistically higher than the sum of the case where only corona discharge is used and the case where only ultraviolet irradiation is used. It has the effect of being able to reliably decompose and purify at the removal rate.

Further, according to the device described in claim 4,
Since the purification treatment can be performed while the treatment gas flows in the container in the axial direction, there is an effect that the harmful component removal rate can be further improved while the flow resistance of the treatment gas is reduced.

Further, according to the purifying apparatus of the fifth aspect, there is an effect that the removal rate according to the fourth aspect can be further promoted.

In addition, according to the purifying device of the sixth aspect, the removal rate according to the fourth aspect can be promoted more significantly without causing an increase in the flow resistance of the processing gas.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along the line II-II of FIG.

FIG. 3 is a diagram showing acetaldehyde removal rate by the apparatus shown in FIG. 1;

FIG. 4 is a cross-sectional view showing a modification of the first embodiment.

FIG. 5 is a view showing the acetaldehyde removal rate by the apparatus shown in FIG. 4;

FIG. 6 is a sectional view showing another modified example of the first embodiment.

FIG. 7 is a longitudinal sectional front view showing an apparatus according to a second embodiment of the present invention.

FIG. 8 is an enlarged sectional view taken along line VIII-VIII of FIG. 7;

FIG. 9 is a perspective view showing an apparatus according to a third embodiment of the present invention.

FIG. 10 is an enlarged sectional view taken along line XX of FIG. 9;

FIG. 11 is a perspective view showing a modified example of the third embodiment.

FIG. 12 is an enlarged sectional view taken along the line XII-XII in FIG. 11;

FIG. 13 is a perspective view showing another modified example of the third embodiment.

[Explanation of symbols]

 1,1 'pipe-shaped container 2,2' gas inlet 3,3 'gas outlet 4,4', 4 "anode electrode 5,5 ', 5", 5a cathode electrode 6 DC power supply circuit 7,7', 7 " Straight UV lamp 8 Power supply for UV lamp

Claims (6)

[Claims] A corona discharge is generated by applying a voltage between two electrodes disposed in a processing gas, and ultraviolet rays are applied to one of the two electrodes, on which oxygen radicals are generated by the corona discharge. A gas purification method characterized by irradiating. 2. The gas purification method according to claim 1, wherein the main wavelength of the ultraviolet light is 253.7 nm. 3. An ultraviolet lamp for arranging two electrodes for corona discharge in a processing gas, and irradiating one of the two electrodes, on which one of the two electrodes oxygen radicals are generated by corona discharge, with ultraviolet light. Is disposed adjacent to the one electrode. 4. A container in which a processing gas flows in from one end and flows out from the other end is provided with two electrodes for corona discharge so as to extend in the flow direction of the processing gas. Wherein the ultraviolet lamp is disposed so as to be adjacent to and extend along one of the two electrodes where oxygen radicals are generated by corona discharge. 5. The container according to claim 3, wherein the cross section of the container is triangular, and the one electrode and the straight tube ultraviolet lamp extending in the flow direction of the processing gas are provided at one corner of the triangle. On the other hand, the other electrode is a flat plate or a curved plate, and the other electrode is disposed on one of the sides of the triangle facing the one electrode, in the flow direction of the processing gas. A gas purification device, wherein the gas purification device is disposed so as to extend. 6. The other electrode of the two electrodes for corona discharge, except for one electrode on which oxygen radicals are generated by corona discharge, is formed in a cylindrical shape, and the inside of the cylindrical shape is filled with a processing gas. The one-electrode and the straight-tube ultraviolet lamp adjacent to the one electrode are arranged so as to extend in the axial direction at a central or substantially central portion in the cylindrical shape, while being configured to flow in the axial direction. Gas purifier.