JPS6354958A - Method and apparatus for cleaning gas flow - Google Patents

Abstract

PURPOSE:To efficiently charge electricity ad to obtain a highly clean gas flow by supplying water to a charged atmosphere charging fine particles in a gas flow. CONSTITUTION:The air sucked in by a fan part 8 is humidified by a water vapor supply part 25 after the filtration through a prefilter 23, and then is charged by a charging part consisting of a net-type photoelectron emitting member 21 and an ultraviolet wave lamp 22, and is changed to a clean air 60. The water in the gas is so supplied that the relative humidity in the gas is >=50%, and pure water or ultrapure water is used for the water to be supplied. As for the method for supplying water, a method using ultrasonic wave, a heated water vapor, a spraying method, etc. may be used. The humidified fine particles are efficiently charged by the photoelectrons emitted from the charging part.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention is applicable to: ■ electronic industry, pharmaceutical industry, food industry, agriculture and forestry industry, medical care,
A method for removing particulates from gas flows such as air, nitrogen, and oxygen in clean rooms, clean booths, clean tunnels, clean benches, safety nets, sterile rooms, bath boxes, sterile air curtains, clean tubes, etc. in the precision machinery industry.

■ Various industries such as flue gas and automobile exhaust gas, ■ Air purification methods in homes, offices, hospitals, etc.

The present invention also relates to an apparatus for carrying out the methods described in (1), (2) and (2) above.

[Conventional technology and its problems]

Conventional indoor air purification methods and devices can be roughly divided into: (1) Mechanical filtration methods (for example, HIEP filters (2) Filtration using high-voltage charged and conductive filters that collect all particulates electrostatically method (e.g. ME
SA filter), but each of these methods had the following drawbacks.

In other words, in the mechanical filtration method, it is necessary to use a fine-mesh filter in order to improve the air cleanliness (class), but in this case, the pressure drop is high, and the increase in pressure drop due to dirt is also significant. and the filter life is short.
Not only is it troublesome to maintain, manage, or replace the filter, but when replacing the filter, it is necessary to stop the work during that time, and it takes a long time to recover, resulting in poor production efficiency. There are nine drawbacks.

In addition, in order to improve the cleanliness of the air, the number of ventilations (the number of times air is circulated by a fan) is increased by t.
In this case, the disadvantage was that the power cost was high.

In addition, conventional filter methods are only intended to remove particulates, so they can be used in industrial clean rooms, but filters almost always have pinholes, which can cause some of the contaminated air to leak out. Therefore, there was a limit to its use in biological clean rooms.Furthermore, in systems that perform all particulate collection electrostatically, the pre-charging section requires a high voltage of, for example, 15 to 70 kV, making the equipment difficult to use. It was large and had problems in terms of safety and maintenance.

In order to solve these problems, the present inventor developed an air purification method using ultraviolet irradiation (Japanese Patent Application No. 59-216295).
, and air purification method using radiation irradiation (patent application 1986)
-18725, Japanese Patent Application No. 61-85996), these methods are effective depending on the field of application and use, but they are not suitable for purifying air containing ultra-fine particles or for application to specific fields. I still can't say it's enough.

[Purpose of the invention]

The present invention provides a method and apparatus for charging fine particles in a gas stream more efficiently, and more specifically, a method for charging fine particles in a gas stream in an atmosphere containing moisture. It is an object of the present invention to provide a method and an apparatus for performing recharging more effectively and reliably.

[Invention lecture]

The present invention provides: 1. A gas flow characterized by supplying moisture to a charged atmosphere in a method for cleaning a gas flow by charging fine particles in the gas flow and then removing the charged fine particles from the gas flow. 2. A gas flow cleaning device comprising at least a moisture supply section, a particulate charging section, and a charged particle collection section on a flow path from a gas flow inlet to a gas discharge port.

Next, based on FIG. 1, an explanation will be given of an air purification method using an ultraviolet radiation method in combination with a clean bench in a clean room, that is, a method of keeping only a part of the working area at a high level of cleanliness.

Inside the clean room 1, after filtering the coarse particles of the outside air introduced from the piping 2 with a pre-filter 3°, it is taken out from the air outlet 4 of the clean room 1 and sent to the air conditioner 6 through the fan 5 along with the air. Air is circulated and supplied with temperature and humidity control and particulates removed by an HKPA filter 7, with a cleanliness level (class) of 10.00.
It is maintained at about 0.

On the other hand, the workbench 15 inside the clean pliers 11 provided with the fan section 8, the ultraviolet irradiation section 9, and the filter 10 in the clean room 1 is maintained in a sterile atmosphere of high cleanliness (class 10).

That is, in the clean bench 11, air with a cleanliness level (class) of about 10,000 inside the clean room 1 is sucked by the fan in the fan unit 8, and fine particles in the air are charged by being irradiated with ultraviolet light in the ultraviolet irradiation unit 9. At the same time, after microorganisms such as viruses, bacteria, yeast, and mold are sterilized, the surface of the workbench 13 is maintained at a high level of cleanliness by removing charged particles with the filter 10.

Instruments, products, etc. can be taken in and out of the workbench 15 in the clean pliers 11 through a movable shutter 12 installed in the cleanbench 11.

A charging section with a humidifying section for applying a charge 11 to particulates in an air stream is shown in detail in FIG. 42.

That is, the air sucked by the fan of the fan unit 8 is filtered by the pre-filter 23 and then humidified by the water vapor supply unit 25, and then passed through the reticulated photoelectron emitting material 21 and the ultraviolet lamp 2.
After the particles are charged in the charging section 2, they are collected by the charged particle collection filter 24, and clean air 60 is obtained.

In the charging section, photoelectrons are emitted by irradiating the photoelectron emitting material with ultraviolet rays from the ultraviolet lamp 22, and the particles in the air 50 including the humidified particles are efficiently charged by the photoelectrons.

The amount of water supplied into the gas stream may be such that the concentration will easily charge the fine particles contained in the gas stream.
The moisture content is such that the relative humidity is 50%, preferably 60% or more, preferably 80% or more.

Moisture can be supplied using well-known methods, such as evaporating water using ultrasonic waves, supplying heated steam, spraying water into a gas stream, or supplying gas R through a perforated plate. A method of passing through water, a method of colliding a gas flow with the water surface, etc. can be used as appropriate.

The quality of the water to be supplied may be as long as it is clean; for example, if you want to obtain highly clean air, use water with a purity appropriate for the purpose, such as pure water or ultrapure water from which fine particles have been removed. Bye. That is, the quality of the supplied water may be of such purity that contamination of the clean gas can be ignored.

Next, the photoelectron emitting material 21 may be any material as long as it emits photoelectrons when irradiated with ultraviolet rays, and the smaller the photoelectric work function, the more preferable it is.

From the viewpoint of effectiveness and economy, Ba, Sr, (a, Y,
Gd.

La, Ce, Nd, Th, Pr, Be, Z
r, Fe, Ni, Zn, Cu.

λg, Pt, Cd, Pb, AI! ,
0. Mg, Au, In, Bi, Nb.

Any one of Si, Ti, Ta, P, or a compound or alloy thereof is preferred, and these may be used alone or in combination of two or more. As the composite material, a physical composite material such as amalgam can also be used.

For example, as compounds, oxides, ferrides, and carbides are
, oxides include Bad, SrO, Gap, y2o6°Gd2O3, Nd2O3, The2. ZrO2, Fe2
O3, ZnO, Cub.

Ag, , O, PtO, PbO, AA'205. MgO
, Engineering n203. BiO, NbO.

Examples include BeO, and borides include YB6. GdB
6°LaB6. CeB6. PrB6. ZrB2
etc.l), and carbides such as ZrC, Tag,
? There are iC, NbC, etc.

In addition, alloys include brass, bronze, phosphor bronze, Ag and Mg.
(2 to 20 wt% Mg), alloys of Cu and Be (1 to 10 wt% Be), and alloys of Ba and A/ can be used. and B
Alloys with e and alloys with Ba and A/ are preferred. Oxides can also be obtained by heating only the metal surface in air or by oxidizing it with chemicals.

Still another method is to heat the material before use to form an oxidized layer on the surface to obtain a stable oxidized layer over a long period of time. As an example of this, a thin oxide film can be formed on the surface of an alloy of Mg and Ag in water vapor at a temperature of 500 to 400 DEG C., and this thin oxide film is stable for a long period of time.

These materials may be used in any shape, such as a plate, pleats, or net, but it is preferable to use a shape that has a large area of irradiation of ultraviolet rays and a large area of contact with the air. Preferably. The photoelectron emitting material and the materials used vary depending on the shape and structure of the device, the desired efficiency, etc.

The type of ultraviolet rays may be any type as long as the photoelectron emitting material can emit photoelectrons when irradiated with the ultraviolet rays, but it is preferable to use one that also has a bactericidal effect.

Laws can be established as appropriate depending on the field of application, content of work, purpose, economic efficiency, etc. For example, in the biological field, it is preferable to use deep ultraviolet rays together in terms of bactericidal action and efficiency.

Charged particles, including dead organisms, are filtered through the filter 10.
．． Collected at 24.

Any collector for charged particles may be used.

A dust collection plate (dust collection electrode) or an electrostatic filter in a normal charging device is common, but a structure in which the collection part itself constitutes an electrode, such as a steel wool electrode, is also effective.

Furthermore, a method of collection using an ion exchange filter, which has already been proposed by the present inventor, is also effective.

For collection, these collection methods can be used alone or in combination of two or more of these methods as appropriate.

Among these collection methods, preferable methods include filter-based methods such as ion-exchange filters (anion-exchange filters, cation-exchange filters), and electrostatic filters, which are highly efficient and can reliably collect charged particles. This is convenient because it allows you to

This is thought to be because excess moisture is also charged, and charged particles are trapped in a portion of the filter in the form of being encapsulated in moisture.

The ion exchange filter is one in which an ion exchanger is supported (supported) on a suitable thin film-like cloth, preferably a cage net-like, woven or fibrous porous support, and is appropriately prepared by a well-known method. be able to.

Examples of the support include aliphatic polymers such as polyethylene, polyglobylene, polybutylene, and polybutene, aromatic polymers such as polystyrene and polyα-styrene, alicyclic polymers such as polyvinylcycloxane, or alicyclic polymers such as polyvinylcycloxane. Hydrocarbon polymers such as copolymers of monomers for producing polymers, polytetrafluoroethylene, polyvinyl 7-vinyl IJ
fluorine-containing polymers such as ethylene-tetrafluoroethylene copolymer, tetra7-ethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, or polyvinyl alcohol. , polyamide, cellulose, polyester, wool, silk or mixtures thereof.

These are used as porous supports, and their shape may be any shape as long as they have a large contact area with the gas flow and have low resistance, for example, an appropriate thin film-like cloth, preferably a woven fabric such as a net, or A fibrous material is used.

The porosity is 10-95%, preferably 50-85%. The shape, thickness, and porosity of the support can be determined as appropriate depending on the shape of the device, the material used, the structure, the desired effect, etc.

The method for supporting (carrying) the ion exchanger on the support is not particularly limited, and the ion exchanger can be supported by any known method.

For example, the support is irradiated with ultraviolet rays or ionizing radiation such as alpha rays, beta rays, electron beams, and gamma rays, or irradiated with oxygen, ozone, chlorosulfonic acid, hydrogen peroxide, benzoyl peroxide,
A method in which, after treatment with peracetic acid or the like, or treatment with two or more of these, an ion exchanger (a monomer having an ion exchange group) or a monomer capable of forming these is grafted onto the entire support. Alternatively, after polyethylene (support) is irradiated with ionizing radiation, a graft copolymer is obtained by reacting with an aqueous solution of acrylic acid and/or methacrylic acid, and this is treated with an aqueous sodium hydroxide solution to perform ion exchange. You get a filter.

Another method is to graft side chains containing styrene or its derivatives, preferably hydroxystyrene, as a main component to the above-mentioned support, and to ionize the graft copolymer partially cross-linked and networked with a diene compound. There is a method of introducing an exchange group.

In this way, fibrous or woven anion exchange filters and cation exchange filters are obtained.

The type, filling amount, and ratio of the anion exchange filter and cation exchange filter to be used depend on the charge state and concentration of charged particles in the gas flow, or accompanying acid gas,
It can be determined as appropriate depending on the type, concentration, etc. of alkaline gas and odorous gas. For example, anion exchange filters are effective for collecting negatively charged particulates and acidic gases, and cation exchange filters are effective for collecting positively charged particulates and alkaline gases. The filling amount of the filter and its ratio may be appropriately determined in accordance with the above-mentioned concentration and concentration ratio of the substance to be collected, taking into account the shape, structure, pressure drop, etc. of the device.

Single-filter types are easy to handle, have good performance,
Although it is effective in terms of economy, it can become clogged if used for a certain period of time.
pt occurs, so by adopting a cartridge structure as necessary and replacing it by detecting pressure loss, stable operation for a longer period of time is possible.

In the above explanation, the humidifying section is installed on the backlight side of the coarse filter 25 and on the upstream side of the ultraviolet lamp, but there is no particular limitation on the installation location. Alternatively, it can be provided at an appropriate location, such as on the downstream side of an ultraviolet lamp, depending on the moisture supply method, the shape of the device, its purpose, effects, etc.

In addition, as a method of charging fine particles in the air, we explained a method of charging without forming an electric field on the charging part, but by irradiating the photoelectron emitting material with ultraviolet rays in an electric field with a relatively high voltage applied, photoelectrons can be charged. is released efficiently,
It is also possible to efficiently charge particles in a gas flow.

Moreover, the same effect can be obtained by irradiating the fine particles with radiation instead of irradiating them with ultraviolet rays.

Example 1 The influence of moisture content was investigated using the air purifier shown in Fig. 2. Air supply amount: 51/1 nin Particles generated: Cigarette smoke (average particle size Q, 5 to α4μ) was diluted as appropriate. The ultraviolet light source used; the photoelectron emission surface of a mercury-xenon lamp; a brass collection filter; a mixture of an anion exchange filter of 60 volume and a cation exchange filter of 40 volume.The water content was adjusted by sending ultrapure water as steam.

The results are shown in Table-1.

Table 1 The method for manufacturing the ion exchange filter used in the examples was as follows.

■ Anion exchange filter Fibrous polypropylene (30μ) is exposed to 2 electron beams in nitrogen.
The sample was irradiated with 0 Mrad and then immersed in a solution containing hydroxystyrene monomer and isoprene to perform graft polymerization.

After the reaction, quaternary amination was performed to obtain an anion exchange filter.

■ Cation exchange filter Fibrous polypropylene (50μ) is exposed to electron beams in nitrogen
A graft reaction was carried out by irradiating with 0 Mrad and then immersing in an aqueous acrylic acid solution. After the reaction, a cation exchange filter was obtained by treatment with a sodium hydroxide solution.

〔Effect of the invention〕

(1) By charging the fine particles in the gas stream in the presence of moisture, (1) charging can be carried out efficiently, and therefore a highly efficient and highly clean gas stream can be obtained.

■ Since the charging efficiency is good, the required energy can be reduced and the device can be made smaller.

(2) Practicality has been further improved in application fields where an atmosphere with high moisture content is preferred, such as the field of biotechnology. In other words, it is possible to supply devices that meet needs.

(3) By collecting charged particles using an ion exchange filter, (1) acidic gas, alkaline gas, or odorous gas can also be collected at the same time.

■ Therefore, the application fields and uses of hydraulic power have been further expanded.

(4) By using ultraviolet irradiation or radiation irradiation as the charging method, it is possible to not only charge fine particles but also sterilize microorganisms and fungi in the gas flow at the same time, resulting in an ultra-highly clean gas.

[Brief explanation of the drawing]

Fig. 1 is a drawing for explaining an air purification method in a clean bench combined method in a clean room using an ultraviolet irradiation method to which the present invention can be applied, and Fig. 2 specifically explains a part for charging particles and a humidifying part. This is a drawing for

Claims (1)

[Claims] 1. A method for cleaning a gas flow by charging particles in the gas flow and then removing the charged particles from the gas flow, characterized by supplying moisture to the charged atmosphere. A method of cleaning gas streams. 2. The method for cleaning a gas stream according to claim 1, wherein water is supplied so that the concentration of water is at least 50% relative humidity. 3. The method for cleaning a gas stream according to claim 1 or 2, wherein the water to be supplied is pure water or ultrapure water. 4. A method for cleaning a gas stream according to claim 1, 2 or 3, in which fine particles in the gas stream are charged by irradiating them with ultraviolet rays or radiation. 5. A method for cleaning a gas stream according to any one of claims 1 to 4, wherein charged particles are collected by a filter method. 6. A method for cleaning a gas stream according to claim 5, wherein the filter is an ion exchange filter or an electrostatic filter. 7. A gas flow purifying device comprising at least a moisture supply section, a particulate charging section, and a charged particle collection section on a flow path from a gas flow inlet to an outlet.