KR20040092811A - Air filtration system and method of the same - Google Patents

Abstract

PURPOSE: Provided are a system for filtering and a method therefor which purify air contaminated by toxic contaminants to prepare breathable air by simultaneously using low temperature plasma and catalytic reaction instead of filter papers and activated adsorbents. CONSTITUTION: The system for air filtering comprises a plasma reactor generating low temperature plasma, a catalytic reactor filled up with an adsorbent or a catalyst and an absorption reactor absorbing and removing products generated by decomposing poisonous materials passing through the plasma reactor and the absorption reactor through decomposition of the low temperature plasma and catalytic reaction by using dielectric heat.

Description

AIR FILTRATION SYSTEM AND METHOD OF THE SAME

The present invention relates to an air purification system and a purification method.

The characteristics of NBC are microparticles and radioactive fallout, which are in the form of fine particles, and chemical gases commonly referred to as "chemical agents" exist mainly in aerosol and gaseous conditions at room temperature (hereinafter referred to as "biogas" through microbial and radioactive fallout and chemical gases). ).

Purification container of gas mask is widely used as a device to purify the air contaminated with CBR gas and to produce respirable air under the CBR, and to supply clean air to the spaces such as evacuation shelters. "There is. The gas filter of the gas mask and the gas filter are composed of a particle filtration unit for removing particulate contaminants and a gas filtration unit for adsorbing or decomposing chemicals in the form of gas or aerosol.

All biological agents and radioactive fallout in the form of microparticles, from anthrax to bacteria as well as to viral microorganisms, can be filtered with high-performance particle filter paper from the particle filter. However, as time passes, the particles adhere to the filter, which increases the air flow resistance (ΔP) between the two ends of the filter (inlet and outlet).

The ASC-activated carbon used to adsorb and decompose chemical gases is evenly distributed from very fine pores to relatively large pores, and these well-developed pores are mainly used as nerve gases such as sarin. Phosphorus compounds) are removed by physical adsorption, and small molecular weight blood gases (e.g. CNCl and HCN) are toxic by chemical reactions due to the action of metals such as silver, copper and chromium infiltrated with activated carbon. It is decomposed and removed into a nonexistent substance.

As described above, the existing gas mask purifier or gas particle filter has excellent filtration performance to remove CBR, but has limited filtration life, and risks of exposure to toxic gas when the filter is replaced, and activated carbon under conditions of high temperature and high humidity during use or storage. There are various problems such as deterioration of adsorption performance and disposal of used filters. Especially, CNCl (CK), a blood agent, is removed by chemical reaction with infiltrated metals rather than by physical adsorption power of activated carbon used as adsorbent of gas mask and gas filter. It is extremely vulnerable to the back and severely deteriorates in long term storage. In order to prevent the aging of activated carbon, new activated carbon treated with organic amine-based chemicals has been recently developed and commercialized. However, it is not a fundamental countermeasure against the finite life and deterioration of life during storage. In particular, the gas mask filter can be easily replaced, but in the case of a gas particle filter attached to a building, a vehicle, a ship, etc., it is not only difficult to replace the filter, but also increases the cost burden due to regular replacement.

In order to compensate for the above disadvantages, the inventors of the present invention "recirculating air filtration system for chemical agent removal" (Patent No. 118423) and "Platinum complex carbon catalyst for combustion reaction for chemical agent removal" (Patent No. 127950) Through oxidative adsorption process or a catalyst oxidation method has been proposed through. Jarvis et al., In the United States Patent (USP 5665143, 1997), combines a PSA (Pressure Swing Adsorption), a circulating air filtration system, and a CBR filter composed of existing high-performance filters and activated carbon. It suggests a way to purify and supply respirable air.

Meanwhile, with the development of low-temperature plasma technology, air purification methods are developed to decompose odorous substances and volatile organic compounds generated at industrial sites using low-temperature plasma technology. However, only some of the polluted air is discharged to the atmosphere. For this purpose, in most cases, the treatment gas concentration is a low concentration of several PPM to several hundred PPM, and the decomposition efficiency is only tens of percent. Therefore, it removes toxic substances such as NBC and provides respirable air to the living space. It is not suitable in a way.

In addition, Birmingham et al. (USP 4954320, 1990) suggest a method for purifying air contaminated with CFCs using a coaxial packed low-temperature plasma reactor, but the possibility of practical use of the reactor and the appropriateness for decomposition products Due to the absence of treatment options, it has not been used as a respirable air production method.

The present invention proposes to solve the above problems, namely, the problem of lowering the service life during the use of the NBC filter, and the new filtration having almost no deterioration in life and performance by using a low-temperature plasma and catalytic reaction instead of the conventional HEPA filter paper and activated carbon adsorbent. It is intended to provide a method, and also to provide a method for producing respirable air by purifying the air contaminated with toxic gases such as NBC.

1 is a schematic view showing the configuration of an air purification system of the present invention.

Figure 2 is a schematic diagram showing another configuration of the air purification system of the present invention.

3 is a cross-sectional view showing a planar dielectric barrier discharge plasma reactor.

4 is a cross-sectional view showing a plate-type dielectric barrier discharge plasma reactor and a plasma / catalyst hybrid reactor in which an adsorbent / catalyst is charged in a discharge space.

5 is a cross-sectional view showing a coaxial plasma reactor and a plasma / catalyst hybrid reactor in which an adsorbent / catalyst is charged in a discharge space.

6 is a sectional view showing a ceramic honeycomb plasma reactor.

*** Explanation of symbols for main parts of drawing ***

1: discharge space 2: electrode

3: electrode 4: dielectric material

5: power

In order to achieve the above object, the present invention is an air purifying apparatus for producing a respirable air by removing the war chemical extinguishing agent or industrial toxic gas, a plasma reactor for generating a low-temperature plasma, hybridized or separated from the plasma reactor, Absorbent decomposition products generated by decomposition of the catalytic reactor filled with an adsorbent or catalyst and the toxic substances passing through the plasma reactor and the absorption reactor are decomposed by the decomposition reaction by low temperature plasma and the catalytic reaction using dielectric heat accompanying plasma discharge. It provides an air purification system comprising an absorption reactor to remove by.

The CFCs or industrial toxic gases include organophosphorus compounds, cyan compounds, sulfur or nitrogen-containing compounds, chlorine or fluorine-containing compounds, bacteria, viruses, and toxins that can be used as biological weapons.

The air purifying system according to the present invention decomposes toxic substances in the air contaminated with a chemical emission agent or industrial toxic gas into ions or radicals generated at the time of discharge by low temperature plasma discharge, and simultaneously or sequentially with the low temperature plasma discharge. The material is decomposed by catalytic reaction and the contaminated air is converted into respirable air through the step of absorbing and removing the reaction product generated from the poisonous material decomposed through the plasma and the catalytic reaction.

Characteristic of the air purification system according to the present invention is the decomposition reaction by low-temperature plasma and catalytic reaction using dielectric heat accompanying plasma discharge (in particular, when a semiconductor material having a photocatalyst such as TiO ₂ is charged, the decomposition reaction by photocatalyst). It is possible to use the decomposition reaction of the toxic substances at the same time to achieve a high removal rate and has the advantage of improving the energy efficiency. In addition, contaminants in the form of microparticles, such as biological agents (bacteria, viruses, and toxins) are charged by electric discharge, and due to electrostatic attraction, these particles are attached to electrodes or fillers and are replenished inside the reactor. It is completely sterilized by active radicals, dielectric heat and ultraviolet rays generated by the discharge. This has been found by several research groups since Hoenig et al. (J. Air Pollution Control Association, 30, 288, 1980) demonstrated that Bacillus thermophilius, a type of bacteria, can be completely removed by low-temperature plasma discharge. .

1 and 2 is a schematic view showing the configuration of a system according to the present invention, Figure 1 shows an example of the low-temperature plasma, catalyst and absorption reactor arrangement according to the air flow. That is, the air contaminated with the toxic gas is purified through the plasma / catalyst hybrid reactor and the absorption reactor as shown in FIG. 1.

As another example, as shown in FIG. 2, the plasma reactor and the catalytic reactor are separated, and thus air is passed through the two reactors in sequence and is purified through the absorption reactor. It is not preferable that the catalytic reactor in the apparatus shown in FIG. 2 be too far from the plasma reactor.

1 and 2, a device for guiding contaminated air into the reactor may use a general blower, and the purified air passing through the reactor may be connected to an air conditioner for temperature control.

In general, catalytic reactions such as chemical agents require a high temperature (above 250 ° C.) and thus require a heating device. However, in the present invention, since the catalyst can be heated using heat generated during plasma discharge in the plasma reactor, a separate heating device is not required.

Various kinds of plasma reactors may be used to achieve the object of the present invention, but a reactor by “dielectric barrier discharge (DBD)” having low power consumption and relatively low heat generation during discharge is suitable.

Plasma discharge using a dielectric barrier occurs between two metal electrodes and at least one of the two metal electrodes (or both electrodes) is coated with a dielectric material so that no direct discharge current flows between the two metal electrodes. In the present invention, the plasma discharge temperature is in the range of room temperature to 450 ° C.

In the present invention, the adsorbent or catalyst supported on the catalytic reactor is preferably in the form of beads or pellets, as well as in the form of granular catalyst aggregates or honeycomb. As the material to be used, metal oxides such as alumina, noble metals such as Pt, Pd, and Rh, transition metal oxides such as CrO _x and CuO _X, and molecular sieves such as Zeolite 13X can also be applied. In addition, semiconductor materials such as titanium dioxide (TiO ₂ ), zirconia (ZrO ₂ ), and SnO ₂ that can be used as photocatalysts may also be used. In particular, when the semiconductor materials are filled, the effect as a photocatalyst may also be expected by ultraviolet rays generated during plasma discharge.

Meanwhile, the absorption reactor is a dry absorption cleaning device mainly absorbing and removing acidic harmful gases which are discharged as decomposition products as toxic substances are decomposed in the plasma / catalyst reactor, and are disposed at the rear of the plasma / catalyst reactor. As absorbents, basic oxides such as CaCO ₃ , CaO, ZnO, MgO, etc. are used, or impregnated or doped materials are used to increase the absorption of acidic gases in activated carbon. monolith) is advantageous to use. In addition, residual ozone discharged to the rear of the plasma / catalyst reactor may be removed by reaction with activated carbon and may also be removed using a MnO ₂ / CuO mixture.

FIG. 3 shows a representative DBD plasma reactor in which two metal electrodes 2 and 3 facing each other are connected to an AC power source 5 and a dielectric material 4 to prevent direct discharge current flow between the two electrodes. ) Is coated or adhered to the electrode. As the dielectric material, a dense ceramic material such as quartz glass or alpha alumina is suitable, but any dielectric material may be used without departing from the object of the present invention.

When the voltage supplied to the electrodes 2 and 3 in the power supply device 5 is sufficiently high, a discharge occurs in the discharge space 1 between the electrodes, and the voltage required for the discharge is determined by the distance between the two electrodes, the thickness of the dielectric, and the nature of the medium. And many other factors. In the present invention, it is preferable to supply an AC voltage ranging from 5 to 30 kV at a specific frequency in the range of 50 Hz to 50 kHz, but in some cases, a DC power source may be used, and an inductance and a charging circuit may be installed for impedance matching with a reactor. You may.

FIG. 4 is a filler 6 in the form of dielectric beads or pellets larger than the permittivity of air in the same reactor as in FIG. 3, and these fillers are capable of adsorbing or catalyzing toxic gases and are capable of plasma discharge. Since it is activated by the generated dielectric heat, it can be expected not only the low temperature plasma reaction but also the effect by the catalytic reaction.

FIG. 5 shows an adsorbent or catalyst filled in a coaxial plasma reactor. The outer tube 8 may be made of quartz or alumina, and a metal thin film may be coated or adhered to the outside of the electrode 7. Use as. In addition, as the internal electrode 9, a metal rod or a wire is used, and when the power source 5 is supplied, plasma discharge occurs in a space between the internal electrode and the external tube. At this time, since the discharge power increases in proportion to the distance between the two electrodes, it is necessary to maintain an appropriate distance.

6 is a plasma reactor in which another honeycomb 11 is inserted between two electrodes 10 made of a porous metal material coated with a dielectric material in another type of plasma reactor for achieving the object of the present invention. It can be expected to facilitate the decomposition of toxic substances by plasma reaction and catalytic reaction. At this time, not only AC but also DC or pulse power may be used. In FIG. 6, since the honeycomb micro-channel array is parallel to the air flow, the air flow resistance is reduced and the plasma discharge start voltage is considerably lowered due to the honeycomb. The honeycomb material may be a ceramic material such as cordierite, mullite, or alumina, and the surface of the honeycomb may be coated with a noble metal catalyst or a metal oxide catalyst to impart oxidative decomposition capability by catalytic reaction. In addition, when the surface of the honeycomb is coated with a semiconductor material capable of exhibiting a function as a photocatalyst, such as TiO ₂ , or when a mixture of these materials during the production of honeycomb is produced, the photocatalytic effect of ultraviolet rays generated during plasma discharge can be expected. In FIG. 6, the electrode 10 may be in close contact with the honeycomb 11 or may be spaced apart from the honeycomb. However, when the distance from the honeycomb is too long or the thickness of the honeycomb itself is too thick, the discharge start voltage is increased. Therefore, it is preferable that the thickness of the honeycomb does not exceed 10 cm, and the distance between the electrode and the honeycomb does not exceed 1 cm. In order to obtain higher removal efficiency, two or more honeycomb electrode configurations as shown in FIG. 6 may be arranged in the housing 12 to increase the residence time of the toxic gas.

Hereinafter, the present invention will be described in more detail with reference to Examples, and the following Examples are intended to explain the present invention more clearly and the scope of the present invention is not limited to these Examples.

Examples 1 to 4 were experiments to remove the NBC and toxic gas by filling the coaxial plasma reactor as shown in FIG. 5 to generate a plasma and installing an absorption reactor packed with activated carbon absorbent pellets at the rear of the plasma reactor. . In order to confirm the breakthrough of the reactor, the exhaust gas concentration was periodically measured by using equipment such as gas chromatography at the rear end of the reactor, and the breakthrough criterion was to detect more than 1 × 10 ^-5 of the inlet pollutant gas concentration. In this case, breakthrough means that the air purification capacity of the reactor is reduced and more than a certain concentration of polluted gas is discharged.In general, 1/10 ⁵ of the inlet concentration is required to remove the polluted gas to release respirable air. Therefore, the breakthrough criteria as above were selected.

Example 1

CK (Cyanogen Chloride) decomposition (1 kHz, AC power supply)

Reactor Fill Discharge power (watt) Inlet concentration (ppm) Test flow rate (liters / minute) Driving time Breakthrough Diameter: 3.0 cm Discharge length: 10 cm Tube material: Quartz Pt / Al ₂ O ₃ 40 2000 2 More than 8 hours radish TiO ₂ 20

Example 2

GB (Sarin) resolution (400 Hz, using AC power)

Reactor Fill Discharge power (watt) Inlet concentration (ppm) Test flow rate (liters / minute) Driving time Breakthrough Diameter: 3.0 cm Discharge length: 10 cm Tube material: Quartz Pt / Al ₂ O ₃ 40 1,000 2 More than 8 hours radish TiO ₂ 40

Example 3

COCl ₂ decomposition (1 kHz, using AC power)

Reactor (Coaxial) Fill Discharge power (watt) Inlet concentration (ppm) Test flow rate (liters / minute) Driving time Breakthrough Diameter: 3.0 cm Discharge length: 10 cm Tube material: Quartz Pt / Al ₂ O ₃ 40 1,000 2 More than 8 hours radish TiO ₂ 40

Example 4

HCN decomposition (400 Hz, using AC power)

Reactor (Coaxial) Fill Discharge power (watt) Inlet concentration (ppm) Test flow rate (liters / minute) Driving time Breakthrough Diameter: 3.0 cm Discharge length: 10 cm Tube material: Quartz Pt / Al ₂ O ₃ 40 1,000 2 More than 8 hours radish TiO ₂ 40

Examples 5 and 6 are experiments to remove the toxic gas by filling the filler in the reactor prepared by stacking the multiple-layered plasma reactor as shown in Figure 4 and generating a plasma, the breakthrough criteria is the previous embodiment Is the same as

Example 5

CH ₃ CN resolution (400 Hz, using AC power)

Reactor (flat type) Fill Discharge power (watt) Inlet concentration (ppm) Test flow rate (liters / minute) Driving time Breakthrough Clearance gap: 3mm Pt / Al ₂ O ₃ 200 1,000 10 More than 8 hours radish

Example 6

DMMP resolution (400 Hz, using AC power)

Reactor (flat type) Fill Discharge power (watt) Inlet concentration (ppm) Test flow rate (liters / minute) Driving time Breakthrough Clearance gap: 3mm Pt / Al ₂ O ₃ 200 1,000 10 More than 8 hours radish

In Example 7, the plasma reactor and the catalyst reactor, which are manufactured by stacking a flat plasma reactor as shown in FIG. 3, are arranged in a separated form as shown in FIG. And an embodiment of the present invention for removing toxic gas by generating a plasma. The results below indicate that when the reactor is connected in series stages, the energy efficiency of the reactor is increased when the toxic gas is removed. That is, in Examples 5 and 6, the energy efficiency is 1/20 (liters / minute.W), whereas in Example 7, 3/20 (liters / minute.W) shows an increase of about three times the efficiency.

Example 7

CH ₃ CN resolution (10 kHz, AC power supply)

Reactor (flat type) Fill Discharge power (watt) Inlet concentration (ppm) Test flow rate (liters / minute) Driving time Breakthrough Pole spacing: 1.5mm Pt / Al ₂ O ₃ 2,000 1,000 300 More than 8 hours radish

According to the present invention, it is possible to produce respirable air by purifying air contaminated with toxic gases such as NBC, by means of a new filtration method having almost no deterioration in life and performance. It has excellent air purification ability and can be applied to various fields such as military and industrial use.

Claims (15)

Air purifying device to manufacture respirable air by removing war chemicals and industrial toxic gases, Plasma reactor for generating a low temperature plasma; And, A catalytic reactor mixed with or separated from the plasma reactor and filled with an adsorbent or a catalyst; And Absorption reactor that absorbs and removes the decomposition products generated by decomposition of the toxic substances passing through the plasma reactor and the absorption reactor by the decomposition reaction by the low temperature plasma and the catalytic reaction using the dielectric heat accompanying the plasma discharge; Air purification system configured to include. The air purification system according to claim 1, wherein the CFC or industrial toxic gas includes organophosphorus compounds, cyan compounds, sulfur or nitrogen compounds, chlorine or fluorine compounds, bacteria, viruses, and toxins that can be used as biological weapons. . The air purification system of claim 1, wherein the plasma reactor generates a dielectric barrier discharge (DBD), wherein two electrodes and at least one of the electrodes are coated with a dielectric material. 4. The air purification system as recited in claim 3, wherein said plasma reactor is comprised of two planar electrodes. The air purifying system of claim 3, wherein the plasma reactor comprises a coaxial external electrode and a core type internal electrode. The air purifying system according to claim 1, wherein when a plasma reactor and a catalytic reactor are mixed, a filler such as an adsorbent or a catalyst is filled between two electrodes of the plasma reactor. The air purifying system according to claim 1, wherein in the case where the plasma reactor and the catalytic reactor are mixed, an integrated ceramic honeycomb coated with a catalyst material is inserted between two electrodes of the plasma reactor. The air purification system according to claim 1, wherein an AC power source of 5 to 30 kV in a frequency range of 50 Hz to 50 kHz is applied to the plasma reactor. The air purification system according to claim 1, wherein the plasma reactor and the catalytic reactor are connected in two or more stages in series. The air purification system of claim 1, wherein the catalyst is in the form of a bead, pellet, granular aggregate, or honeycomb. 12. The material used as a catalyst is a metal oxide supported by precious metals such as Pt, Pd, and Rh, a metal oxide supported by transition metal oxides such as CrO _X and CuO _X , zeolite 13X, and the like. Molecular sieve or air purification system which is at least one selected from a semiconductor such as TiO ₂ , ZrO ₂ , SnO ₂ . The air purification system according to claim 1, wherein the absorbent included in the absorption reactor is obtained by processing activated carbon type absorbent or basic oxides such as CaCO ₃ , CaO, ZnO, MgO, etc. into pellets or monoliths. Decompose toxic substances in the air contaminated with chemical and biological agents or industrial toxic gases into ions or radicals generated during discharge by low temperature plasma discharge, Simultaneously or sequentially with the low temperature plasma discharge, decompose the toxic substance by a catalytic reaction, Absorbing and removing the reaction product generated from the toxic substances decomposed through the plasma and the catalytic reaction. The method of claim 13, wherein the CFC or industrial toxic gas includes organophosphorus compounds, cyan compounds, sulfur or nitrogen-containing compounds, chlorine or fluorine-containing compounds, bacterial anaviruses and toxins that can be used as biological weapons. . The method of claim 13, wherein the catalytic reaction is performed by a catalytic reaction activated by dielectric heat generated during plasma discharge and a photocatalytic reaction by ultraviolet rays.