JP3202250B2 - Hazardous gas removal method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for purifying a gas or a space, and more particularly to a harmful gas (a toxic gas, a harmful gas, an odorous gas, an odorous gas) existing in a gas or a space. concerning the collection and removal how of). INDUSTRIAL APPLICABILITY The removal method and apparatus of the present invention can be used to remove harmful gas discharged in homes, offices, hospitals, or various industries, and harmful gas generated in a closed space (static space). Next, an example is shown. (1) NOx, tobacco smell in homes, offices and hospitals,
Treatment of toilet odor and various chemical odors. (2) Treatment of exhaust gas such as NOx and SOx from various combustion facilities. (3) Exhaust gas treatment of automobiles. (4) Treatment of various harmful gases in and around clean rooms in the semiconductor industry, the pharmaceutical industry, the food industry, the agriculture and forestry industry, the medical industry, and the precision machinery industry.

[0002]

2. Description of the Related Art Conventionally, the emission of exhaust gas from various industries and industries and the exhaust gas from automobiles into the atmosphere have been legally and other regulated from the viewpoint of pollution prevention. The emission of oxides is severely restricted as a causative agent of acid rain and photochemical smog. Although many methods of treating nitrogen oxides (NOx) and sulfur oxides (SOx) in exhaust gas subject to emission control have been proposed in the past, there are various problems in practice. For example, as a conventional exhaust gas denitration technique, a reduction method by adding ammonia, a reduction method using a catalyst, a radiation irradiation method, and the like have been proposed.

[0003] Each of these conventional methods has the following problems. Reduction method by addition of ammonia; denitration effect is low. Reduction method using a catalyst; when used continuously, catalyst performance is reduced. Since metals and precious metals are used as catalysts, they need to be reviewed from the viewpoint of resource saving.
Susceptible to dust and acidic substances. Irradiation method: Since secondary products such as ammonium nitrate and ammonium sulfate are generated in large quantities, it is necessary to separately treat by-products. In addition, since ammonia is added in any of these methods, ammonia that is not consumed in the denitration reaction is discharged as leaked ammonia, resulting in secondary pollution. In addition, it is necessary to review the use of ammonia and resource saving.

Next, a description will be given of fine particles and harmful gases (including odorous gases) generated by smoking in homes and offices. These substances are generally regarded as a so-called tobacco odor, and the odor is of course harmful (eg, gas generating), and the demand for collection and removal has been particularly increasing in recent years. For the collection and removal of these, there are proposed methods and apparatuses using various removal materials such as those using activated carbon or vegetable essential oil, but all of these removal materials have insufficient performance, and new methods have been proposed. -Appearance of devices is expected.

[0005]

As described above, various methods for treating harmful gases discharged from factories and homes have been proposed. However, there are various problems, and a sufficiently satisfactory removal method has not been proposed. Did not. The present invention solves the above problems, and is easy to handle, compact and inexpensive.
The purpose is to provide the law .

[0006]

In order to achieve the above object, according to the present invention, in removing harmful gas present in a space, ultraviolet rays and / or radiation are irradiated to remove the harmful gas present in the space.
One or more hazardous gases other than at least sulfur compounds
Harmful gases were micronized, after the fine particles are charged by photoelectrons is obtained by a method of removing harmful gas, characterized in that collecting the charged particulates.

Further , the present invention includes a harmful gas atomizing unit having an ultraviolet and / or radiation irradiation source, a charging unit for charging the fine particles by photoelectrons, and a collecting unit for collecting the charged fine particles . Achieved using harmful gas removal equipment
Can be In the above method, the fine particles are charged by irradiating the photoelectron emitting material with ultraviolet light and / or radiation to emit photoelectrons and use the photoelectrons. The charging of the fine particles is preferably performed in an electric field.

Next, various constituent members of the present invention will be described in detail. The atomizing section is a section for converting harmful gas into fine particles, and is mainly composed of an irradiation source for exhaust gas. The irradiation source may be any source that can convert harmful gas into fine particles. In addition to UV irradiation, electromagnetic waves, lasers,
Radiation can be selected and used by conducting preliminary tests as appropriate according to the field of application, the component and concentration of the harmful gas to be treated, the scale of the apparatus, the shape, the effect, the economy, and the like. The irradiation converts the harmful gas into fine particles. In the conversion to fine particles (fine particle formation), 2
Irradiation sources having a wavelength of 60 nm or less, preferably 200 nm or less are effective, and ultraviolet and / or radiation irradiation is usually suitably used in terms of effect and operability.

For example, a mercury lamp,
Hydrogen discharge tubes (deuterium lamps) emit alpha rays,
β-rays and γ-rays are used.
Radioactive isotopes such as 0, cesium 137, and strontium 90, or radioactive waste produced in a nuclear reactor and a radioactive material that has been appropriately processed and processed as a radiation source, a method using a nuclear reactor as a direct radiation source, A method using a particle accelerator such as an electron beam accelerator is used. When irradiating an electron beam with an accelerator, high-density irradiation can be performed by performing at a low output, which is effective. The accelerating voltage is 500
kV or less, preferably 50 kV to 300 kV.

Next, the charged portion of the fine particles is a portion for applying the charge of the harmful gas which has been made into fine particles, and its structure is shown in FIG. 2, which is a major feature of the present invention. The exhaust gas 7 containing the fine particles is introduced into the charging section 3 of the fine particles. The fine particles are mainly applied to a UV-emitting lamp 9 by a UV-transmitting glass material and a photoelectron emitting material 8 made of Au applied in a thin film on the surface.
The charged particles are efficiently charged by the photoelectrons 10 emitted by the ultraviolet irradiation from the substrate, become charged fine particles, and are collected and removed by the charged fine particle collecting section 4 on the rear side. Reference numeral 11 denotes an electrode, which is provided to charge the fine particles in an electric field.

Regarding the charging of the fine particles by photoelectrons, there are various proposals by the present inventors, and they can be used as appropriate.
The following are the main proposals. 1. JP-A-61-178050 (PS Patent 4,7
No. 50,917), 2. JP-A-62-244459,3. JP-A-63-7
No. 7557,4. JP-A-63-100955; JP-A-2-8638,6. JP-A-2-10034,
7. 7. Japanese Patent Application No. 1-120563, 8. Japanese Patent Application No. 2-153
No. 335

The respective configurations will be described. The photoelectron emitting material may be any material that emits photoelectrons by irradiating ultraviolet rays, and a material having a small photoelectric work function is preferable. Ba, Sr, Ca, Y, G
d, La, Ce, Nd, Th, Pr, Be, Zr, F
e, Ni, Zn, Cu, Ag, Pt, Cd, Pb, A
1, C, Mg, Au, In, Bi, Nb, Si, Ti,
One of Ta, U, B, Bu, Sn, and P, or a compound, alloy, or mixture thereof is preferable, and these are used alone or in combination of two or more. As a composite,
Physical composites such as amalgam may also be used.

For example, compounds include oxides, borides and carbides, and oxides include BaO, SrO, and Ca.
O, Y ₂ O ₅ , Gd ₂ O ₃ , Nd ₂ O ₃ , ThO ₂ , Z
rO ₂ , Fe ₂ O ₃ , ZnO, CuO, Ag ₂ O, La
₂ O ₃ , PtO, PbO, Al ₂ O ₃ , MgO, In _{2
O 3, BiO, NbO, YB} 6 is to include BeO, also _{borides, GdB 6, LaB 5, NdB} 6, CeB
₆ , BuB ₆ , PrB ₆ , ZrB _{2 and the} like, and further, as carbides, UC, ZrC, TaC, TiC, Nb
C and WC. In addition, brass, bronze,
Phosphor bronze, alloy of Ag and Mg (Mg is 2 to 20 wt.
%), An alloy of Cu and Be (Be is 1 to 10 wt%) and an alloy of Ba and Al can be used.
g, an alloy of Cu and Be, and an alloy of Ba and Al are preferable. The oxide can also be obtained by heating only the metal surface in air or oxidizing it with a chemical.

Still another method is to heat before use,
An oxide layer can be formed on the surface to obtain a stable oxide layer over a long period of time. As an example, an oxide film can be formed on the surface of an alloy of Mg and Ag in steam at a temperature of 300 to 400 ° C. at a temperature of 300 to 400 ° C. This oxide thin film is stable for a long time. Also, the present inventor:
As already proposed, a photoelectron emitting material having a multi-layered structure can be suitably used (Japanese Patent Application No. 1-155857).
Further, a substance capable of emitting photoelectrons in the form of a thin film can be added to an appropriate base material and used. This example is an example in which Au is added on a glass base material in the form of a thin film. These materials may be used in any shape such as a plate shape, a pleated shape, a curved surface shape, and a net shape, but a shape having a large ultraviolet irradiation area and a large air contact area is preferable.

The emission of photoelectrons from the photoelectron emitting material can be effectively implemented by appropriately using a reflecting surface, a curved reflecting surface, etc., as already proposed by the present inventor (Japanese Patent Application Laid-Open No. Sho 63). -100955 publication). The shape of the photoelectron emitting material and the shape of the reflection surface differ depending on the shape and structure of the device or the desired efficiency, and can be determined as appropriate.

The type of the ultraviolet light may be any as long as the photoelectron emitting material can emit photoelectrons by the irradiation.
Usually, a mercury lamp, a hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube and the like can be appropriately used. Depending on the field of application, those having a bactericidal (sterilizing) action are also preferred. The type of the ultraviolet ray can be appropriately determined depending on the application field, work content, application, economy, and the like. For example, in the biological field, it is preferable to use far ultraviolet rays in combination from the viewpoints of sterilization and efficiency. For example, it is preferable to use a germicidal lamp (254 nm is the main wavelength) because a germicidal (sterilizing) action is added to the charge of the present invention. As the ultraviolet light source, any one that emits ultraviolet light can be used, and the field of application, the shape of the device,
It can be appropriately selected and used depending on the structure, effect, economy, and the like.

The charging of the fine particles by photoelectrons is efficiently performed by irradiating the photoelectron emitting material with ultraviolet light in an electric field. The present inventor has already proposed charging in an electric field (eg, JP-A-61-178050,
JP-A-62-244459, Japanese Patent Application No. 1-120.
No. 563). The electric field of the present invention is between 0.1 V / cm and 5 kV / cm.
The suitable electric field strength can be determined by appropriate preliminary tests and studies in accordance with the application field, conditions, apparatus shape, scale, effect, economy, and the like. For example, a weak electric field may be used for purification of an enclosed space, but a relatively strong electric field is used for various industrial exhaust gases having a large amount of processing gas.

Also, by irradiating radiation instead of irradiating ultraviolet rays, the fine particles are similarly charged, and the same effect can be obtained. Irradiation can be carried out in the same manner as has already been proposed by the present inventor (JP-A-62-24459). Since the charge by photoelectrons is charged with high efficiency even with fine ultrafine particles (eg, <0.1 μm), the collection and removal of the fine particles can be performed efficiently. The charging of the fine particles can be performed by increasing the particle diameter of the fine particles upon charging. Increase the particle size of the fine particles,
The inventor has already proposed a charging method (Japanese Patent Application No. 1-120564), and the method can be used for charging fine particles appropriately depending on the application field. Next, the charged fine particle collecting unit 4 is a part that collects and removes charged fine particles,
A well-known method and apparatus can be applied as appropriate.

That is, any material for collecting charged fine particles can be used as long as it can collect charged fine particles. Generally, a dust collecting plate (dust collecting electrode) or an electrostatic filter method in a normal charging device is used. However, a wool-like substance such as steel wool or tungsten wool is used as an electrode (wool-like electrode material). A structure in which the collecting portion itself forms an electrode is also effective. Electret materials can also be suitably used. Further, an ion exchange filter (fiber) already proposed by the present inventor is also effective depending on the application field. The ion exchange filter is preferable depending on the field of application because it can collect harmful gas, odorous gas, and the like, which are difficult to collect by this method. These trapping materials can be used singly or in combination of two or more depending on the application field, device scale, shape, economy, and the like.

[0020]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. Embodiment 1 As a specific example of the present invention, FIG. 1 shows a schematic diagram of an apparatus when applied to the treatment of SOx in combustion exhaust gas generated from a fuel combustion furnace. In FIG. 1, an exhaust gas 1 containing 120 ppm of SOx (mainly SO ₂ ) discharged from a combustion furnace containing an average of 120 ppm is irradiated with ultraviolet rays in an atomizing section 2 to emit SO ₂ in the exhaust gas 1.
x is converted into fine particles (aerosol). Reference numeral 3 denotes a charged portion of the fine particles. The fine particles are efficiently charged by the photoelectrons generated from the above-described photoelectron emitting material, become charged fine particles, and are then collected by a charged fine particle collecting section 4 at the rear.
The removed and cleaned exhaust gas (SOx 10 ppm) is discharged from the chimney 5. Reference numeral 6 denotes an exhaust gas suction and discharge fan.

In the example shown in FIG. 1, the fine particle forming section 2, the fine particle charging section 3, and the charged fine particle collecting section 4 are individually installed. However, these parts are applied to the application field, the apparatus scale, the shape, the effect, and the like.
The functions can be integrated as appropriate depending on the economic efficiency or the like, or can be installed and implemented at an appropriate position. For example, (1) the fine particle forming section 2 and the fine particle charging section 3 are integrated, (2) the fine particle charging section 3 and the collecting section 4 are integrated, and further (3) the fine particle forming section 2 and the charging section 3,
All of the collecting units 4 can be integrated. The selection of the irradiation source of the atomizing unit 2 and the charging unit 3 and the collection material of the charged particles, the presence or absence of the integration of the atomizing unit 2, the charging unit 3 and the collecting unit 4, and the type of integration Whether to integrate the functions) or the method of installing these parts can be determined by appropriately examining and conducting preliminary tests according to the application field, the shape, structure, effect, economy, etc. of the device.

As an example of a general form, in the case of a large-scale treatment such as industrial exhaust gas, radiation is used as an irradiation source, and the atomizing section 2, the charging section 3, and the collecting section 4 are arranged as shown in FIG. And set it up individually. That is, in a large-scale processing, it is practically important to keep the running cost of the apparatus low because of a large processing amount. For this purpose, it is preferable to operate each component under optimal conditions. In addition, collection part 4
Is required to be independent, to be able to discharge trapped fine particles appropriately, and to be able to continuously operate for a long time. For collecting the charged fine particles in such a case, a dust collecting plate (dust collecting electrode) can be suitably used.

Next, as a small-scale form, there is removal of harmful gas (odorous gas) generated by smoking or the like in a home or office. In this case, as in the embodiment described later, the microparticulation unit, the charged part of the fine particles, and the collection part of the charged fine particles are all performed by one part using ultraviolet rays as the irradiation source. That is, in a field having a small amount of processing such as a home or an office, it is practically preferable that the apparatus be compact (miniaturized). Therefore, all functions are performed in one box.

Embodiment 2 Air cleaning in an office will be described with reference to the basic configuration diagram of the present invention shown in FIG. In the room 11, fine particles (particulate matter) 12 and harmful gases (including odorous gases, such as aldehydes, ketones, pyridines,
Pyrroles, nitriles, nitrogen oxides, NO, NO ₂ )
13 are floating. The air cleaning is performed by an ultraviolet lamp 14, a photo-emissive material 15, an electrode 16 for installing an electric field, a collecting plate 16 for charged fine particles, and an ultraviolet reflecting surface 17 installed on the ceiling.

Here, the electrode for setting the electric field also serves as a collecting plate for charged fine particles. That is, the fine particles 12
Charged by photoelectrons 18 emitted from the photoelectron emitting material 15 irradiated with the ultraviolet lamp 14 to become charged fine particles 19, and the charged fine particles 19 are collected by a charged fine particle collecting plate 16. On the other hand, the harmful gas 13 is collected and removed by the configuration of the present invention.

That is, the harmful gas 13 is the ultraviolet lamp 1
4 is converted into fine ultrafine particles (aerosol) 20 by ultraviolet rays having a wavelength of 260 nm or less. The fine ultrafine particles 20 are left as they are, or a part thereof adheres and aggregates to the fine particles 12 generated by smoking, and the photoelectron emission material 1
The charged particles are charged by the photoelectrons 18 emitted from the sample 5 and become charged particles 19, and the charged particles are collected by the collecting plate 1 of the charged particles 1.
Collected in 6. The fine ultrafine particles are highly efficiently charged by photoelectrons, and thus can be easily collected and removed. In this way, the fine particles (particulate matter) 12 and the harmful gas (including odorous gas) 13 in the room 11 are collected and removed, and the room 11 becomes clean air.

In the above, the irradiation of the photoelectron emitting material with ultraviolet rays uses the curved reflecting surface 17 and the ultraviolet lamp 14.
UV light is applied to the plate-shaped photoelectron emitting material 15 with high efficiency. As the ultraviolet lamp 14, a deuterium lamp is used. The electrode 16 is provided to charge the fine particles 12 generated by smoking or the like and the fine particles generated from the harmful gas in an electric field. That is, the photoelectron emitting material 15 and the electrode 16
An electric field is formed between them.

The fine particles are charged efficiently by irradiating the photoelectron emitting material 15 with ultraviolet rays in an electric field. The electric field voltage here is 50 V / cm. Also,
The electrode 16 also serves as a collecting material for charged fine particles, and uses a dust collecting plate. In this example, if an air agitation (mixing) unit, for example, a low-power fan is installed in one part of the room or in the vicinity where the ultraviolet irradiation is performed, indoor air flows, so that
The effect is enhanced, which is preferable.

[0029]

According to the present invention, the following effects can be obtained. (1) Upon removal of the harmful gas, the harmful gas was irradiated with ultraviolet light and / or radiation, so that the harmful gas was turned into fine particles and became easy to handle (easily processed). (2) In removing the harmful gas, by performing charging by photoelectrons subsequent to 1 above, fine ultrafine particles (for example,
<0.1 μm), the particles easily became charged fine particles, and were easily collected and removed. Since the charge by photoelectrons is uniform and highly efficient, the handling of the charged fine particles is facilitated. Since the charged particles are substantially uniform, the collection, removal, and hand rigging of the charged particles are facilitated.
As described above, the charged fine particles could be easily collected and removed by using an appropriate charged fine particle collecting material.

(3) By using ultraviolet irradiation and / or radiation irradiation, it is possible to give the irradiation both the action of making the harmful gas fine (action) and the action of charging the fine particles (action). Can be formed in a single box and the generated fine particles can be charged in one box), so that a compact and inexpensive device is obtained depending on the application field. A suitable irradiation source can be appropriately selected depending on the application field, the scale of the apparatus, the shape, the effect, the economic efficiency, and the like, so that it can be widely applied to various fields. For example, large-scale treatment fields such as exhaust gas treatment in various industries are useful for radiation irradiation, and small-scale treatment fields such as offices and homes are useful for sterilization (sterilization) like ultraviolet irradiation and biotechnology. Fields requiring good operability and small-scale but highly efficient removal of harmful gases include ultraviolet irradiation, particularly in combination with ultraviolet light having a sterilizing wavelength.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus in which the present invention is applied to exhaust gas treatment.

FIG. 2 is a configuration diagram of an apparatus for charging fine particles.

FIG. 3 is a schematic explanatory view in which the present invention is applied to office air purification.

[Explanation of symbols]

1, 7: exhaust gas, 2: atomizing part, 3: charging part, 4: trapping part, 5: chimney, 6: exhaust fan, 8, 15: photoelectron emitting material, 9, 14: ultraviolet lamp, 10, 18 : Photoelectron,
11: electrode, 12: fine particle, 16: electrode / collecting plate, 1
7: UV reflective surface, 19: charged fine particles

Continued on the front page (51) Int.Cl. ⁷ Identification code FIG21H 5/00 B01D 53/34 132A // B03C 3/38 (72) Inventor Kazuhiko Sakamoto 2-4-1 Minamimotojuku, Urawa-shi, Saitama (56) References JP-A-54-5865 (JP, A) JP-A-63-267423 (JP, A) JP-A-1-99633 (JP, A) JP-A-63-77557 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) B01D 53/32 B01D 53/56 B01D 53/60 B01D 53/74 B03C 3/38

Claims (6)

(57) [Claims] 1. A method for removing harmful gas present in a space by irradiating ultraviolet light and / or radiation to the harmful gas present in the space.
A method for removing harmful gas, comprising: forming at least one harmful gas other than at least a sulfur compound of the harmful gas, charging the fine particles by photoelectrons, and collecting the charged fine particles. 2. The method for removing harmful gases according to claim 1, wherein the wavelength of the fine particles formed by irradiation with ultraviolet rays and / or radiation is 260 nm or less. 3. The method for removing harmful gases according to claim 1, wherein the charging of the fine particles by photoelectrons is performed by irradiating the photoelectron emitting material with ultraviolet rays and / or radiation. 4. The method for removing harmful gases according to claim 3, wherein at least a part of the photoelectron emitting material is made of a substance having a small photoelectric work function. 5. The photoelectron emitting material has at least one part thereof
Ba, Sr, Ca, Y, Gd, La, Ce, Nd, T
h, Pr, Be, Zr, Fe, Ni, Zn, Cu, A
g, Pt, Cd, Pb, Al, C, Mg, Au, In,
Bi, Nb, Si, Ta, Ti, U, B, Eu, Sn,
4. The method for removing harmful gases according to claim 3, wherein the method comprises one kind of material selected from P and its compounds. 6. The photoelectron emitting material has at least one part thereof,
Ba, Sr, Ca, Y, Gd, La, Ce, Nd, T
h, Pr, Be, Zr, Fe, Ni, Zn, Cu, A
g, Pt, Cd, Pb, Al, C, Mg, Au, In,
Bi, Nb, Si, Ta, Ti, U, B, Eu, Sn,
4. The method for removing harmful gases according to claim 3, comprising two or more alloys, mixtures or composites selected from P and its compounds.