CN113701295A

CN113701295A - Air purification equipment and air purification method

Info

Publication number: CN113701295A
Application number: CN202110792427.XA
Authority: CN
Inventors: 不公告发明人
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-07-13
Filing date: 2021-07-13
Publication date: 2021-11-26

Abstract

The invention relates to air purification equipment and an air purification method, which belong to the field of air purification. Then a corona field purifier is adopted to adsorb and remove the particulate matters in the air flow, and the gaseous pollutants are subjected to secondary conversion and decomposition. In addition, a first ultraviolet lamp is arranged at the outlet end of the corona field purifier, and the gaseous pollutants are converted and decomposed for the third time by utilizing the synergistic effect of the corona field processor and the first ultraviolet lamp. Then, the oxidation catalytic purifier is adopted to completely oxidize and decompose the gaseous pollutants into carbon dioxide and water, and simultaneously destroy the protein structure on the surfaces of microorganisms and viruses. Finally, a reduction catalytic purifier is adopted to reduce redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the air flow into oxygen, nitrogen, carbon dioxide and water, thereby purifying the air more comprehensively.

Description

Air purification equipment and air purification method

Technical Field

The invention belongs to the field of air purification, and particularly relates to air purification equipment and an air purification method.

Background

In the present large environment where the air quality is gradually deteriorated, the air purification is gradually receiving attention. The main methods for improving indoor air quality currently include: (1) the air filtering method comprises the following steps: the filter material mainly comprises glass fiber, synthetic fiber, filter paper or filter cloth made of the fiber, active carbon with adsorption effect and the like, and the filter material is used for filtering particulate matters and peculiar smell in air to purify the air. However, these porous filter materials increase the air flow resistance, and as the service life is prolonged, the filtering effect will be reduced, and if the filter materials are not replaced in time, secondary pollution will be generated; (2) an electrostatic dust removal method: firstly, the particulate matters in the air flow are charged, and then the particulate matters are collected by a dust collecting device with heterogeneous electricity to achieve the purpose of purifying the air, but the method can not completely kill bacteria in the air, especially viruses with small volume, has low purification efficiency on gaseous pollutants, and can also generate excessive ozone which is harmful to human bodies; (3) the ultraviolet sterilization method comprises the following steps: the ultraviolet ray is utilized to kill microorganisms and viruses in the air, but the ultraviolet ray has no effect on purifying particles, the purification of gaseous pollutants needs time, and overproof ozone can be generated; (4) the cold plasma purification method comprises the following steps: the strong ionization field and gas discharge generated by the cold plasma generator ionize water molecules and gas molecules in the air, and through complex excitation, dissociation and ionization processes, active groups with extremely active chemical properties are generated to generate a series of oxidation-reduction reactions with pollutants in the air, so that volatile organic matter molecules are decomposed. These free radicals also have a strong inactivating effect on microorganisms. Meanwhile, the floating particulate matters descend after being charged and gathered through the inelastic collision of the charged particles on the floating particulate matters. However, recent studies have shown that (http:// dx. doi. org/10.1016/j. buildenv.2021.107750) the cleaning effect of this method is not significant and has significant side effects. This study, written by researchers at the university of illinois, the university of portland state, and the colorado state university, found that while ionizing devices reduced some of the VOCs, including xylene, other compounds, particularly oxygenated VOCs (e.g., acetone, ethanol), and toluene, increased. It was also found that the overall concentration of PM2.5 was not reduced despite minor changes in the concentration of floating particulate matter. The air purifier market is full of peer review studies of inadequate test standards, confusion in terminology, and lack of effectiveness and safety.

Disclosure of Invention

The invention aims to provide air purification equipment and an air purification method, which can effectively remove particulate matters, microorganisms, viruses and gaseous pollutants.

Therefore, the invention provides air purification equipment, which sequentially comprises the following components in the air flowing direction:

the cold plasma generator is connected with the high-voltage generator, positive and negative ions are emitted into air flow to be purified by the cold plasma generator, the gaseous pollutants are subjected to primary conversion and decomposition by active substances generated by the cold plasma generator, and particles in the air flow become charged particles after the positive and negative ions are adhered to the particles;

the oxidation catalytic purifier thoroughly oxidizes and decomposes the gaseous pollutants into carbon dioxide and water, and destroys protein structures on the surfaces of microorganisms and viruses;

the reduction catalytic purifier reduces redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the gas flow into oxygen, nitrogen, carbon dioxide and water.

Preferably, for the air with higher concentration of gaseous pollutants, the method further comprises the following steps:

the static magnetic field generator is arranged between the cold plasma generator and the oxidation catalytic purifier, the direction of a static magnetic field generated by the static magnetic field generator is perpendicular to the direction of the airflow or the movement direction of the charged particles in the airflow, and the static magnetic field generated by the static magnetic field generator can gather the particles with opposite charges in the airflow;

and a corona field processor connected with the high voltage generator, the corona field processor is arranged between the static magnetic field generator and the oxidation catalytic purifier, the corona field processor comprises a positive corona field and a negative corona field which are arranged in parallel, the positive corona field collects the residual positively charged particles in the air flow, the negative corona field collects the residual negatively charged particles in the air flow, the particles collected by the static magnetic field generator are charged again through the positive corona field and the negative corona field and are attracted and collected by the corona field collecting electrodes with different charges, and active substances generated by the positive corona field and the negative corona field carry out secondary conversion and decomposition on the gaseous pollutants.

Preferably, slit or hole have been seted up to corona field processor's exit end, corona field processor's collection dirt utmost point's surface still is equipped with first ultraviolet lamp, the ultraviolet ray of first ultraviolet lamp passes slit or hole and shines on the corona field filament in the corona field processor, corona field processor and first ultraviolet lamp's synergism carry out the conversion decomposition of gaseous pollutant the third time, and first ultraviolet lamp can carry out ultraviolet inactivation to the remaining virus that is not collected the processing by corona field processor because of small in the air current simultaneously and handle.

Preferably, the outlet end of the oxidation catalytic purifier is further provided with a second ultraviolet lamp, and the oxidation catalytic purifier and the second ultraviolet lamp cooperate to completely oxidize gaseous pollutants remained in the gas flow into carbon dioxide and water.

Preferably, the outlet end of the reduction catalytic purifier is also provided with a far infrared lamp for increasing the reduction catalytic temperature.

Preferably, the positive corona field inlet of the corona field treater is close to the positive ion emitting electrode of the cold plasma generator, and the negative corona field inlet of the corona field treater is close to the negative ion emitting electrode of the cold plasma generator.

Preferably, the oxidation catalytic converter is a two-way catalyst in a motor vehicle, and the reduction catalytic converter is a three-way catalyst in a motor vehicle.

In addition, the invention also provides an air purification method which is realized by the air purification equipment and comprises the following steps:

firstly, emitting positive and negative ions into air flow to be purified by adopting an ion emitting electrode of a cold plasma generator, and carrying out primary conversion and decomposition on gaseous pollutants by using active substances generated in the process; respectively adsorbing positive and negative charges on the particles in the airflow to form charged particles;

secondly, the airflow treated in the first step passes through an oxidation catalytic purifier to thoroughly oxidize and decompose gaseous pollutants into carbon dioxide and water, and simultaneously destroy protein structures on the surfaces of microorganisms and viruses;

and step three, the airflow treated in the step two passes through a reduction catalytic purifier to reduce redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the airflow into oxygen, nitrogen, carbon dioxide and water.

Preferably, for air with higher particulate matter concentration, after the charged particulate matter is formed in the step one, the particulate matter with opposite charges are close to each other by using the dual action of coulomb force between positive and negative charges and lorentz force generated by a static magnetic field generator, and the particles aggregate and grow after collision contact discharge; and the airflow is also led to pass through a corona field processor, so that the residual positively charged particles in the airflow are collected through a positive corona field, the residual negatively charged particles in the airflow are collected through a negative corona field, the particles which lose charges and gather to be long pass through the positive corona field or the negative corona field and are then charged again, and then the particles are attracted and collected by a dust removal electrode with different charges, and meanwhile, active substances generated by the positive corona field and the negative corona field carry out secondary conversion and decomposition on gaseous pollutants.

Preferably, the first step also blows the ozone and the active substances generated by the dielectric barrier discharge ionizer into the air flow, so that the ozone and the active substances are additionally added into the air flow on the basis of the ozone and the active substances generated in the first step.

Compared with the prior art, the invention has the characteristics and beneficial effects that:

(1) the air purifying equipment adopts the cold plasma generator to carry out primary conversion and decomposition on gaseous pollutants in the air flow, so that particles in the air flow become charged particles, and the static magnetic field generator is utilized to gather the particles with opposite charges. Then, a corona field purifier is adopted to adsorb and remove the particulate matters in the air flow, and the gaseous pollutants are subjected to secondary conversion and decomposition. In addition, a first ultraviolet lamp is arranged at the outlet end of the corona field purifier, and the gaseous pollutants are converted and decomposed for the third time by utilizing the synergistic effect of the corona field processor and the first ultraviolet lamp. Then, the oxidation catalytic purifier is adopted to completely oxidize and decompose the gaseous pollutants into carbon dioxide and water, and simultaneously destroy the protein structure on the surfaces of microorganisms and viruses. Finally, the reduction catalytic purifier is adopted to reduce redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the air flow into oxygen, nitrogen, carbon dioxide and water, thereby achieving the purpose of comprehensively purifying the air.

(2) The air purification equipment of the invention divides oxidation-reduction catalysis into two parts, namely an oxidation catalytic purifier and a reduction catalytic purifier, wherein the oxidation catalytic purifier firstly catalyzes ozone to oxidize and decompose volatile gaseous organic matters into carbon dioxide and water, and simultaneously enables the ozone to destroy protein structures on the surfaces of microorganisms and viruses, and then the reduction catalytic purifier catalyzes nitrogen oxides to reduce nitrogen oxides into nitrogen and oxygen, and simultaneously reduces residual ozone into oxygen, thereby removing the volatile gaseous organic matters, nitrogen oxides, viruses and the like in air flow, and also removing the residual ozone, thereby purifying the air more comprehensively, not generating ozone exceeding the standard and ensuring safe use. Because the invention firstly utilizes the oxidizing power of high-concentration ozone to purify VOC and germ virus, the process can also consume part of ozone and then reduce and purify residual ozone. Therefore, the method is more reasonable compared with a method adopting two types of catalysis to be carried out simultaneously.

(3) The air purification equipment adopts the binary catalyst used by the motor vehicle as the oxidation catalytic purifier and adopts the ternary catalyst used by the motor vehicle as the reduction catalytic purifier, thereby well applying the catalytic conversion technology and components for the motor vehicle to the air purification equipment and reducing the equipment cost.

(4) The air purification equipment of the invention does not adopt filtering material, so the air purification equipment has small wind resistance, low noise, low energy consumption and large treatment flow.

(5) When the concentration of the particulate matters in the air is lower, the air purification equipment can be simplified, so that the volume of the equipment is reduced, and the practicability is improved.

(6) The air purification equipment provided by the invention can be used for purifying air provided with an air conditioning system, is also suitable for purifying indoor air under a simple heating condition, and effectively prevents carbon monoxide poisoning.

Drawings

Fig. 1 is a schematic view of an air cleaning apparatus.

Figure 2 is a schematic diagram of a corona field processor.

Fig. 3 is a schematic view of a bipolar ionizer currently in common use on the market.

Fig. 4 is a schematic circuit diagram of a circuit for converting an ac voltage from an ac power source to a 12V dc voltage.

Fig. 5 is a schematic circuit diagram of a circuit for converting a 12V dc voltage to a dc high voltage.

Fig. 6 is a schematic view of a static magnetic field.

Fig. 7 is a schematic diagram of a winter heating system commonly used in rural areas.

Fig. 8 is a schematic view of an air purification apparatus in which the concentration of particulate matter is low and the concentration of VOC is high, and dangerous germs and viruses may be contained in the air.

Fig. 9 is a schematic diagram of an air purification apparatus in which the concentration of particulate matter and VOC is low, but dangerous germs and viruses may be contained in the air.

Figure 10 is a schematic representation of the air quality change after treatment with a prototype of the invention.

FIG. 11 is a graph showing VOC concentration versus time for various treatment conditions.

FIG. 12 is a graph showing the relationship between the concentration of ozone and time after the high concentration of ozone generated by the dielectric barrier ozone generator is subjected to the reduction catalyst treatment of the present invention.

FIG. 13 is a schematic diagram showing the relationship between ozone concentration and time after a cold plasma treatment step and a reduction catalyst treatment step in a prototype according to the present invention.

The attached drawings are marked as follows: 1-power supply, 2-cold plasma generator, 3-corona field processor, 31-positive corona field dust collecting electrode, 32-negative corona field dust collecting electrode, 33-positive corona field filament, 34-negative corona field filament, 4-slit or hole, 5-first ultraviolet lamp, 6-oxidation catalytic purifier, 7-reduction catalytic purifier, 8-static magnetic field generator, 9-second ultraviolet lamp and 10-far infrared lamp.

Detailed Description

In order to make the technical means, innovative features, objectives and functions realized by the present invention easy to understand, the present invention is further described below.

The examples described herein are specific embodiments of the present invention, are intended to be illustrative and exemplary in nature, and are not to be construed as limiting the scope of the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification of the present application, and these technical solutions include technical solutions which make any obvious replacement or modification for the embodiments described herein.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such as "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Fig. 1 shows an air cleaning device, in which arrows indicate the direction of the air cleaning process. When particulate matter concentration is lower in the air current, in order to save equipment volume, reduce cost, improve the practicality, air purification equipment includes cold plasma generator 2, oxidation catalytic converter 6 and reduction catalytic converter 7 in proper order along the air flow direction. The power supply 1 supplies power to the whole air purification equipment, and the power supply 1 can be a rechargeable battery type direct current or an indoor alternating current power supply.

The cold plasma generator 2 is connected with the high voltage generator, the cold plasma generator 2 is connected with a direct current positive and negative high voltage output electrode and can emit positive and negative ions to air flow to be purified, and particles (including microorganisms and viruses) in the air flow become charged particles after the positive and negative ions are adhered. In addition, the active substance generated by the cold plasma generator 2 carries out primary conversion and decomposition on the gaseous pollutants, and the particles in the air flow are adhered with positive and negative ions to form charged particles.

The oxidation catalytic converter 6 is used for thoroughly oxidizing and decomposing gaseous pollutants into carbon dioxide and water, and destroying protein structures on the surfaces of microorganisms and viruses. The oxidation catalytic converter 6 is preferably a two-way catalytic converter in a motor vehicle. The oxidation catalyst used in the oxidation catalytic converter 6 is a noble metal catalyst (including platinum and palladium), a metal oxide catalyst (e.g., MgO, Al)₂O₃、SiO₂And aluminosilicate molecular sieves), and semiconductive oxides (e.g., Fe₂O₃、V₂O₅、TiO₂CuO, NiO, ZnO, CdO). In order to improve the virus fire extinguishing rate, the humidity of the air flow passing through the catalyst can be increased by adopting an ultrasonic humidifying or water evaporating mode.

The reduction catalytic converter 7 is used to reduce excess ozone, small amounts of nitrogen oxides and residual gaseous pollutants in the gas stream to oxygen, nitrogen, carbon dioxide and water. The reduction catalyst 7 is preferably a three-way catalyst in a motor vehicle. The reduction catalyst used in the reduction catalyst purifier 7 is a noble metal catalyst (including rhodium) or a metal oxide catalyst (including transition metal oxides such as manganese, cobalt, and copper, and rare earth metal oxides).

For air with higher concentration of gaseous pollutants, the air purification equipment sequentially comprises a cold plasma generator 2, a static magnetic field generator 8, a corona field processor 3, a first ultraviolet lamp 5, an oxidation catalytic purifier 6, a second ultraviolet lamp 9, a reduction catalytic purifier 7 and a far infrared lamp 10 along the air flowing direction.

The static magnetic field generator 8 is connected with the high voltage generator, the static magnetic field generator 8 is arranged between the cold plasma generator 2 and the oxidation catalytic purifier 6, and the static magnetic field generated by the static magnetic field generator 8 can gather particles with opposite charges in the air flow. The static magnetic field generated by the static magnetic field generator 8 is perpendicular to the direction of the air flow or the moving direction of the charged particulate matters in the air flow. The static magnetic field generator 8 is a pair of magnets having high coercive force, north and south poles. The direction of the magnetic field generated between the two poles is perpendicular to the direction of the air flow. Under the dual action of Lorentz force and Coulomb force, the particles with positive charges and the particles with negative charges are close to each other, and discharge and aggregation are carried out after collision.

The corona field processor 3 is connected to a high voltage generator. The plasma generator 2, the static magnetic field generator 8 and the corona field processor 3 are connected with the same high voltage generator. The corona field treater 3 is disposed between the static magnetic field generator 8 and the oxidation catalytic converter 6, and the corona field treater 3 includes a positive corona field and a negative corona field arranged in parallel, as shown in fig. 2. The positive corona field comprises a positively charged positive corona field filament 33 and a negatively charged positive corona field collector 31 arranged in parallel; the negative corona field includes negatively charged negative corona field filaments 34 and positively charged negative corona field collector electrodes 32 arranged in parallel. The positive corona field collecting electrode 31 and the negative corona field collecting electrode 32 are plate-shaped or cylindrical metal plates or metal cylinders. The negative corona field dust collecting electrode 32 is connected with a positive high-voltage output electrode of the high-voltage generator, the voltage of which is not lower than 4000V, and the negative corona field filament electrode 34 is connected with a negative high-voltage output electrode of the high-voltage generator, the voltage of which is not lower than 4000V. The positive corona field dust collecting electrode 31 is connected with a negative high-voltage output electrode of the high-voltage generator, which is not lower than 3000V, and the positive corona field filament 33 is connected with a positive high-voltage output electrode of the high-voltage generator, which is not lower than 3000V.

The positive corona field air inlet of the corona field processor 3 is close to the positive ion emission electrode of the cold plasma generator 2, and the residual particles with positive charges in the air flow are relatively close to the positive corona field air inlet, and rapidly fly to the positive corona field dust collecting electrode 31 to be discharged and deposited under the double actions of the repulsion of the positive corona field filament 33 and the attraction of the positive corona field dust collecting electrode 31. The negative corona field air inlet of the corona field processor 3 is close to the negative ion emission electrode of the cold plasma generator 2. The particles with negative charges remained in the air flow are relatively close to the air inlet of the negative corona field, and quickly fly to the negative corona field dust collecting electrode 32 to be discharged and deposited under the dual actions of the repulsion of the negative corona field filament electrode 34 and the attraction of the negative corona field dust collecting electrode 32. The particulate matter collected by the static magnetic field generator 8 is newly charged by the positive corona field and the negative corona field and attracted and collected by the dust removing electrodes charged with different kinds of electric charges, and the active substances generated by the positive corona field and the negative corona field perform secondary conversion decomposition on the gaseous pollutants.

In addition, corona field treater 3's exit end still is equipped with first ultraviolet lamp 5, and corona field treater 3 and first ultraviolet lamp 5's synergism carry out the conversion decomposition of gaseous pollutant for the third time, and first ultraviolet lamp 5 can carry out the ultraviolet inactivation to the remaining virus that is not collected the processing by corona field treater 3 because of small in the air current simultaneously. Preferably at the exit end of corona field treater 3 has seted up slit or hole 4, first ultraviolet lamp 5 sets up the surface at corona field treater 3's collection dirt utmost point, the ultraviolet ray of first ultraviolet lamp 5 passes slit or hole 4 and shines on the corona in corona field treater 3. The ultraviolet light generated by the first ultraviolet lamp 5 has a wavelength of not more than 154 nm.

The outlet end of the oxidation catalytic purifier 6 is also provided with a second ultraviolet lamp 9, and the residual gaseous pollutants in the air flow are thoroughly oxidized into carbon dioxide and water under the synergistic action of the oxidation catalytic purifier 6 and the second ultraviolet lamp 9. The second ultraviolet lamp 9 is installed in such a manner that ultraviolet light is irradiated in parallel to the gas flow passage of the oxidation catalyst converter 6. The wavelength range of the ultraviolet light generated by the second ultraviolet lamp 9 is 185-375 nm.

The outlet end of the reduction catalytic purifier 7 is also provided with a far infrared lamp 10 for increasing the reduction catalytic temperature. The far-infrared lamp 10 is installed in such a manner that infrared light is irradiated in parallel to the gas flow path of the reduction catalyst 7. The far-infrared lamp 10 generates infrared light in a wavelength range of 8 to 25 μm. It should be noted that other means for increasing the reduction catalyst temperature may also be employed, including: 1. the heat generated by the oxidation catalytic converter 6 is directly introduced into the reduction catalytic converter 7; 2. the reduction catalytic purifier 7 is put into the heating air flow or the fuel gas coal-fired smoke exhaust air flow; 3. communicating the reduction catalytic purifier 7 with the inlet air or the outlet air of an air conditioning system; 4. the reduction catalyst is heated by resistance heating.

When the concentration of particulate matter in the air flow is low, the air purification method specifically comprises the following steps:

firstly, emitting positive and negative ions into air flow to be purified by adopting an ion emitting electrode of a cold plasma generator 2, and carrying out primary conversion and decomposition on gaseous pollutants by using active substances generated in the process; the particles in the air flow respectively adsorb positive and negative charges to form charged particles.

And step two, the airflow treated in the step one passes through an oxidation catalytic purifier 6, so that gaseous pollutants are thoroughly oxidized and decomposed into carbon dioxide and water, and protein structures on the surfaces of microorganisms and viruses are damaged.

And step three, the airflow treated in the step two passes through a reduction catalytic purifier 7, and redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the airflow are reduced into oxygen, nitrogen, carbon dioxide and water.

When the concentration of particulate matter in the air flow is high, the air purification method specifically comprises the following steps:

firstly, emitting positive and negative ions into air flow to be purified by adopting an ion emitting electrode of a cold plasma generator 2, and carrying out primary conversion and decomposition on gaseous pollutants by using active substances generated in the process; the particles in the air flow respectively adsorb positive and negative charges to form charged particles. After the charged particles are formed, the particles of opposite charges are close to each other by the dual action of the coulomb force between the positive and negative charges and the lorentz force generated by the static magnetic field generator 8, and are aggregated and grown after collision contact discharge. The gas stream is then passed through a corona field processor 3, the positively charged particles remaining in the gas stream are collected by a positive corona field, the negatively charged particles remaining in the gas stream are collected by a negative corona field, the particles which have lost their charge and accumulated in large particles are recharged after passing through the positive or negative corona field and are then attracted to and collected by the differently charged dust-collecting electrodes, and at the same time the active species generated by the positive or negative corona field undergo a second conversion decomposition of the gaseous pollutants. In addition, in order to effectively purify the air, a first ultraviolet lamp 5 is arranged outside the outlet end of the corona field processor 3, the gaseous pollutants are converted and decomposed for the third time by utilizing the synergistic effect of the corona field processor 3 and the first ultraviolet lamp 5, and meanwhile, the first ultraviolet lamp 5 can perform ultraviolet inactivation treatment on residual viruses which are not collected and treated by the corona field processor 3 due to small volume in the air flow. And additionally blowing the ozone and the active substances generated by the dielectric barrier discharge ionizer into the air flow, thereby additionally adding the ozone and the active substances into the air flow on the basis of the ozone and the active substances generated in the step one.

And step two, in order to improve the virus fire extinguishing rate, the humidity of the air flow passing through the catalyst can be increased by adopting an ultrasonic humidifying or water evaporating mode. The gas stream is then passed through an oxidation catalytic converter 6 to completely oxidize and decompose the gaseous pollutants into carbon dioxide and water, while destroying the microbial and viral surface protein structures. In addition, in order to better purify the air, a second ultraviolet lamp 9 is arranged at the outlet of the oxidation catalytic purifier 6, and the residual gaseous pollutants in the air flow are more effectively and completely oxidized into carbon dioxide and water by utilizing the synergistic action of the oxidation catalytic purifier 6 and the second ultraviolet lamp 9.

And step three, the airflow treated in the step two passes through a reduction catalytic purifier 7, and redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the airflow are reduced into oxygen, nitrogen, carbon dioxide and water. In addition, in order to improve the reduction catalytic efficiency, a far infrared lamp 10 is provided at the outlet of the reduction catalytic converter 7 to increase the reduction catalytic temperature.

1. Cold plasma treatment

The mechanism of low temperature plasma contaminant removal is generally thought to be accomplished by excitation of energetic electrons generated by a gas discharge. Electrons in the gas are accelerated in the high-voltage electric field and then undergo inelastic collision and elastic collision with surrounding molecules, atoms, electrons and other particles, wherein the molecules and atoms are excited, dissociated and ionized to generate more free electrons, and the newly generated electrons are accelerated by the high-voltage electric field, and the collision, excitation and ionization occur again to excite the gas molecules or atoms to a higher energy level. In which high-energy electrons play a leading role, and which strike O in the background gas₂、N₂And H₂O generation O, N, OH and O₃And the active particles react with pollutant groups or molecules through a series of reactions of the free radicals with strong oxidizing property, and finally, the pollutants are completely oxidized.

As shown in fig. 3, a bipolar ionizer currently used in the market has two high voltage output electrodes, positive and negative, for emitting positive and negative ions, respectively. In order to reduce the emission resistance and increase the ion emission, the output electrode is usually in a needle tip shape or a carbon fiber bundle shape, and even fullerene is used as an electrode material. The two electrodes are separated by a certain distance D, a large number of gas molecules with the same charge can appear around one output electrode, and the gas molecules can also make particles in the air carry the same charge, so that the gas molecules repel each other to form ion wind. In the region between the two electrodes, there will be some gas molecules or particles (including microorganisms and viruses) with different sign charges, which attract each other due to coulomb force, and annihilate into neutral molecules or particles with larger size after collision. However, a large number of ionic gas molecules which have no chance of colliding with the opposite sign charges and being annihilated still exist in the whole space, and the ionic gas molecules meet with the particulate matters to charge the particulate matters, so that the particulate matters can be converted from fly ash into dust fall.

The proportion P of the particles which can collide with each other and annihilate to all the particles mainly depends on the air velocity S, the distance D between the two output electrodes and the dc output voltage V. I.e. there is a functional relationship of P ═ f (S, D, V). Under the condition that S and V are fixed, the smaller D is, the larger P is, the better the effects of sterilizing, disinfecting and purifying gaseous pollutants are, but the smaller D value can cause air to be directly punctured to form arc discharge between two poles, so that the power of the ion generator is rapidly increased, and the parts are heated and heated to cause safety problems. Furthermore, the concentration of ozone generated by the ionizer is also directly related to the value of D, with smaller D giving higher ozone concentration. In order to avoid ozone exceeding the standard, manufacturers usually calculate the appropriate D value according to S and V, or use electrode material with very small resistance (such as fullerene) to reduce the ozone concentration. The same problem also exists in the selection of the parameter V, the direct-current voltage V is improved, the purification and dust collection effects are good, but the risk of air breakdown short circuit is high, and particularly the ozone concentration is easy to exceed the standard. The output voltage of the bipolar ionizer on the market is greatly limited. The output voltage of the ion purifier for window air conditioner is not more than 3000V, and the output voltage of the ion purifier for central air conditioner is not more than 6000V. When the distance between the output electrodes is less than 25mm, the directions of ions emitted by the two electrodes are required to be staggered so as to avoid that positive and negative particles collide and annihilate relatively quickly to generate excessive ozone. Due to the limitations of output voltage and electrode distance, the power of the conventional bipolar ion generator is small, generally not more than 5W, and the concentration of generated ions is not large. Although there are products on the market that are rated to generate 1000 ten thousand ions per second, 4000-6000 ten thousand ions per cubic centimeter, at distances of 3, 4 meters from the electrode, there are still 4-5 ten thousand ions per cubic centimeter. But is virtually negligible (less than 10 < 11 > min) compared to 1 cc containing 2.69 x 10 < 19 > oxygen molecules. The actual decontamination of such products is far less effective than advertising. The main reason for this is that ozone limits the increase in power.

The last step of the air treatment in the present invention can reduce ozone to oxygen, so there is no concern that the bipolar ionizer will generate too much ozone in the first step. Therefore, the output voltage of the bipolar ionizer can exceed 6000V, and a suitable range is 3000-20000V. The spacing D between the generator output electrodes may be small, but too small a spacing may still cause short circuit overheating, with a suitable electrode spacing in the range of 20-250 mm. The bipolar ion generator can reach the power of more than 20-30 watts, and the quantity of emitted ions is far more than that of similar products on the market. Therefore, the dust collecting effect is greatly enhanced, tiny viruses can also carry positive or negative charges in airflow with higher ion concentration, if viruses with different polarity charges are close to each other, the viruses can attract each other, and the viruses are gathered into uncharged particles after discharge. Part of the virus is also inactivated during the discharge aggregation process.

The circuit design of the bipolar ionizer employed in the present invention is not substantially different from the products already on the market. In order to be suitable for various power supplies, such as 24, 115 and 208 ac power supplies shown from left to right in fig. 3, manufacturers generally use the circuit shown in fig. 4 to convert ac voltage from ac power supply into 12V dc voltage, and then convert 12V dc voltage into dc high voltage output through the circuit design shown in fig. 5.

Although the distance between the positive and negative ion emitting electrodes is not large, there is still a large proportion of charged particles (including microorganisms and viruses) that do not have the opportunity to collide with each other and to accumulate after discharge. To this end, the present invention employs a static magnetic field during the last of steps one to enhance the aggregation of the charged particles. The static magnetic field is shown in fig. 6, where the distance between the two poles is referred to as the gap width d. The direction of the magnetic field lines in the air gap is from top to bottom, and is perpendicular to the direction of the moving speed v (from the paper surface to the inside in the figure) of the negatively charged particles and the positively charged particles in the magnetic field.

The lorentz force vector F felt by an electric particle in an x-y plane motion is qv × B. Wherein q is the particle charge, v is the particle motion velocity vector, and B is the magnetic induction vector. From the formula, the direction of F should be perpendicular to the x-y plane. So, according to the left-hand rule, negatively charged particles are subjected to a lorentz force F1 from left to right, and positively charged particles are subjected to a lorentz force F2 from right to left. Under the dual action of the lorentz force and the electrostatic force (coulomb force) between the particles, the negatively charged particles and the positively charged particles move along with the airflow and simultaneously and rapidly approach to each other until the particles collide with each other and are discharged, and then the particles are aggregated into neutral particles with larger volume.

The generation of the static magnetic field in the present invention requires a permanent magnetic material of high coercive force. The neodymium iron boron is a magnet product which is most widely applied at present, and the magnetic energy product can reach 50MGOe which is 10 times of that of ferrite. The coercive force Hc (coercive force) is large, and a stable static magnetic field can be generated for a long time. Considering the adverse effect of the width d of the air gap between the north (N) pole and the south (S) pole of the static magnetic field on Hc, and taking into account the air flow rate, a suitable range for d in the present invention is 10-100 mm.

Although most of the charged particles can be collected after the static magnetic field is used, a part of the charged particles can still go forward along with the airflow and enter the corona field before being collected.

2. Corona field treatment

Direct current corona refers to a special discharge phenomenon under the action of an electrostatic field. Is a non-uniform electric field discharge at (or above) standard atmospheric pressure. The non-uniformity of the electric field is due to the small radius of curvature of the surface of one or more of the electrodes. The electrode structure of the corona field may be for a needle, for a plate, a wire pair coaxial cylinder, two parallel wires, etc. The corona discharge is self-sustaining discharge without any effect of a catalyst, and the discharge current is generally 10^-6-10^-3Ampere, whose discharge is characterized by intense spatial ionization and excitation at the surface of an electrode with a small radius of curvature, producing a distinct luminescent layer (corona layer). The electric field strength at which the drying air generates corona is about 3MV per meter or 30KV per cm at 1 atm. When there is only one small radius of curvature corona electrode, it is called a unipolar corona. The unipolar corona has a positive corona and a negative corona, depending on the high electrostatic polarity of the corona-initiating electrode connection. The positive corona and the negative corona have different discharge mechanisms, and the positive corona structure is easy to corona due to the fact that space charge distribution is beneficial to the positive corona (corona can be generated by an electrode with small curvature radius and positively charged at a lower voltage), so that less ozone is generated. But also tends to create an arc between the corona-initiating positive electrode and the negatively charged electrode. Therefore, the voltage is limited and the purification efficiency is low. On the contrary, the negative corona is not easy to riseThe corona has more ozone, but the breakdown voltage is higher than that of the positive corona, and the purification efficiency is higher. If both electrodes are electrodes with a small radius of curvature, a bipolar corona is formed, a positive corona and a negative corona are present simultaneously, and the current through the outer zone is bidirectional and consists of positively and negatively charged particles. Under the same conditions, the corona inception voltage of the bipolar corona is lower than that of the unipolar corona inception voltage. The invention adopts two parallel corona fields to treat particulate matters and gaseous pollutants.

After the air flow passes through the positive and negative electrodes of the cold plasma generator 2, most of the particles (including microorganisms and viruses) of the air flow are charged, and after the charged particles pass through the north and south poles of the static magnetic field generator 8, the discharges are aggregated into uncharged particles under the dual action of lorentz and coulomb forces. If entering the positive corona field, the polymerized particles firstly adsorb the positive charges around the filament 33 of the positive corona field to be charged again, and then are attracted to the positive corona field dust collecting electrode 31 to be discharged and deposited by the coulomb force of the negatively charged positive corona field dust collecting electrode 31. If the polymerized particles enter the negative corona field, the polymerized particles firstly adsorb negative charges around the negative corona field filament 34 to be charged again, and then are attracted to the negative corona field dust collecting electrode 32 to be discharged and deposited by the coulomb force of the positively charged negative corona field dust collecting electrode 32. While positively charged particles that have not been polymerized with negatively charged particles after passing through the magnetic field, due to their proximity to the positive corona field (because the positive electrode of the ionizer is closer to the air inlet of the positive corona field than the negative electrode), are immediately repelled by the positively charged positive corona field filaments 33, attracted by the negatively charged positive corona field collector 31, and finally discharged for deposition on the positive corona field collector 31. Similarly, negatively charged particles that have not been polymerized with positively charged particles after passing through the magnetic field will also enter the closer negative corona field and discharge deposit on the positively charged negative corona field collector electrode 32.

The adoption of corona field to purify particles is a well-established technology. The corona wire material is typically stainless steel or tungsten, and to reduce the corona voltage, the wire diameter is typically no more than 0.5 mm. Some have sharp burrs on the filament to make corona more likely and reduce the amount of ozone. The corona collector material is typically stainless steel. The structural design of the positive and negative corona field in the invention includes, but is not limited to, filament-plate-shaped dust collecting electrode structure and filament-cylindrical dust collecting electrode structure, wherein the filament is parallel to the dust collecting electrode, and the distance between the filament and the dust collecting electrode is related to the diameter of the filament and the electrostatic voltage. The smaller the diameter, the higher the voltage, and the larger the pitch may be. The invention does not consider the ozone generating quantity when the corona field is treated, so the voltage of the corona field can be designed to be higher. The voltage of the positive corona filament is not lower than +3000V, and the voltage of the dust collecting electrode is not lower than-3000V. The voltage of the negative corona filament electrode is not lower than-4000V, and the voltage of the dust collecting electrode is not lower than + 4000V. The invention can also adopt a needle corona electrode-plate dust collecting electrode structure or a double corona design with a plurality of metal wires arranged in parallel. In a dicorotron design with multiple wires arranged in parallel, all particulate matter is deposited on the wires and over time can affect corona generation and require frequent cleaning. However, the corona field is small in size and is very suitable for being installed on an air inlet of an air conditioner.

3. Corona in conjunction with ultraviolet light treatment

In addition to treating purified particles, corona fields can also be used to treat Volatile Organic Compounds (VOCs). The corona discharge ionizes the gas, i.e. the gas medium near the electrodes is locally broken down to appear corona. When the active electrons generated by ionization have bond energies similar to or identical to those of C-H, C-C or C ═ C bonds in VOCs, these bonds are broken, thereby destroying the structure of the VOCs. The free radicals can react with organic molecules or radicals to oxidize organic substances into CO completely in the presence of oxygen₂And H₂And O. Research shows that when the direct current corona discharge current is 1.5mA, the degradation rate of indoor benzene reaches 90-95%. Studies have also shown that negative coronas are somewhat more efficient at purifying than positive coronas, especially in humid air conditions. Additional studies have shown that the peak voltage, pulse rise time, and frequency and gas residence time of the pulsed corona field have a large effect on the efficiency of VOCs degradation. However, the energy consumption of the corona treatment of VOC is high, and O is generated₃And harmful byproducts such as nitrogen oxides (NOx). In addition, the structural design and manufacturing accuracy of the equipment components are highly required to prevent short-circuiting of the arc.

The ultraviolet light treatment of the VOCs is called UV photolysis, and the VOCs are irradiated in a short distance by using an ultraviolet lamp with a specific wavelength, and partial VOCs are oxidized into carbon dioxide, water and hydrogen chloride by destroying chemical bonds of pollutants; and simultaneously part of the macromolecular VOCs is cracked into small molecular compounds containing C-O, C ═ O bonds. However, the single UV photolysis technique has a large limitation in purification use. First, more toxic incomplete oxidation byproducts may be produced. Such as UV, photolysis of trichloroethylene, generates phosgene (phosgene) which is about 10 times more toxic than chlorine. Second, photolysis with shorter wavelength (185nm or less) UV light also produces ozone. The use of ultraviolet rays having a longer wavelength can reduce the amount of ozone, but the purification efficiency is poor.

The invention adopts the mode of corona field and ultraviolet light to cooperatively process VOCs. The chemical bonds of substances with bond energies less than 647KJ/mol are first broken using ultraviolet light at a wavelength of 185 nm: such as H-H (436KJ/mol), C-C (332KJ/mol), C ═ C (611KJ/mol), S-H (339KJ/mol), S-S (268KJ/mol), O ═ O (498KJ/mol), C-H (413KJ/mol), C-F (485KJ/mol), C-N (305KJ/mol), C-O (326KJ/mol), O-H (464 KJ/mol). The chemical bonds of most common VOC contaminants, including hydrogen sulfide, ammonia, thiols, benzenes, etc., are broken by 185nm uv light. However, the bond energy of C ═ O is 728KJ/mol, and UV light is applied to contaminants containing this chemical bond, such as phosgene (COCl) mentioned above₂) Has a limited treatment effect. Thus, corona field co-processing is required. The energy of the active substance generated by the corona field is related to the voltage, and the bond energy level of C ═ O can be reached under certain conditions, so that the bond energy level is damaged, and the deficiency of UV photolysis can be compensated. On the contrary, the chemical bond energy of the byproduct oxynitride of the corona field is generally lower than the upper limit of the bond energy decomposed by 185nm ultraviolet light, for example, 230KJ/mol for O-N and 607KJ/mol for O ═ N. Therefore, under the condition of weak corona field, the ultraviolet light decomposition can make up the deficiency of the purification effect and reduce the amount of the by-products generated by the former.

As shown in figure 2, in order to simplify the equipment, the invention installs the first ultraviolet lamp 5 on the back half external surface of the corona field dust collecting electrode, and opens the slit or hole 4 on the plate or cylinder dust collecting electrode, so that the ultraviolet light can penetrate the slit or hole 4 to enter the interior of the corona field and irradiate on the positive corona field filament 33 and the negative corona field filament 34. The slit is suitable for long tubular ultraviolet lamp and has length corresponding to that of the lamp tube. The wavelength of the UV lamp is generally no higher than 154 nm. The power of the uv lamp can be selected from a range of several watts to hundreds of watts depending on the concentration of VOCs contained in the air stream and the size of the room space to be purified. Considering that the time required for the ultraviolet photolysis is generally 0.05 to 0.5s, if the air flow rate is 1m/s, the corona field length (or ultraviolet lamp tube length) of the portion participating in the ultraviolet photolysis ranges from 50 to 500 mm. The length of the whole corona field including the dust collecting section should not be less than 450 mm.

4. Oxidative catalytic treatment

The invention can generate new oxidation by-products when corona is cooperated with ultraviolet light treatment. Such as aldehydes or ketones, from the oxidation of hydrocarbons. These by-products need to be further oxidized to CO₂And H₂And the waste water can be discharged after O. The present invention employs oxidation catalysis in the next step. Generally the corona field may act synergistically with the photocatalytic technique. The design thereof is divided into two types. One is built-in, that is, the photocatalyst is arranged in a corona field, high-energy particles in a corona discharge area are transited to generate ultraviolet rays, and electrons of catalytic molecules are excited to transit to a high energy level, so that the synergistic effect of a plasma technology and a catalytic technology is realized. The advantage of this design is that the ultraviolet light generated by corona is directly used as the light source needed by the photocatalyst, and no additional light source is added. However, the limitation is that the contact area of the catalyst with the gas flow is small and charged particles can accumulate on the surface of the catalyst, resulting in catalytic failure. Another synergistic design is the post-position, i.e. after the photocatalyst is placed in the corona area, the harmful by-products and residual organics from corona treatment are treated by catalytic techniques. The design can remove the particulate matter firstly, reduce the accumulation of the particulate matter on the catalyst, and has large contact area and low resistance between the gas flow and the catalyst. But requires the addition of a special light source in the gas flow channel of the photocatalyst. As shown in figure 1, the invention adopts a post-positioned design, namely, a honeycomb-shaped oxidation catalyst net is arranged behind a corona field, and airflow directly enters the catalytic net after coming out of the corona field. But does not arrange a light source inside the airflow channel of the catalytic net so as to avoid blockageInstead of a second uv lamp 9, a channel is provided at the exit end of the catalytic mesh. Ultraviolet light is injected into the catalytic mesh through a plurality of gas flow channels. Promoting the continuous oxidation of newly generated and residual VOC. In addition, an ultrasonic humidifier can be arranged before the airflow enters the catalytic net to increase the humidity of the airflow entering the catalytic net so as to improve the virus inactivation rate.

The key factors for improving the efficiency of the oxidation catalysis step include catalyst components, resistance of the catalyst to the gas flow, catalytic action time, gas flow temperature and humidity, ultraviolet lamp parameters and the like. The following are distinguished:

(1) oxidation catalyst

The most important influencing factors are the performances of the photocatalytic material, including catalytic activity, use conditions, service life, cost price and the like. The noble metal catalyst has strong activity, high efficiency and wide range of catalytic pollutants, and can catalyze without ultraviolet irradiation. But is easy to be poisoned and has higher cost. The metal oxide has low cost, is not easy to be poisoned and has loose light source condition. But the activity and catalytic efficiency are poor. The semiconductor oxide has high efficiency and low cost, but needs stronger ultraviolet light. In general, the oxidation catalyst employed in this step includes noble metal catalysts, including platinum and palladium; metal oxide catalyst including MgO, Al₂O₃、SiO₂And an aluminosilicate molecular sieve; and a semiconductor oxide catalyst comprising Fe₂O₃、V₂O₅、TiO₂CuO, NiO, ZnO and CdO.

In order to reduce the manufacturing cost, the present invention may employ a catalytic converter for an automobile as the honeycomb catalyst in this step. The vehicle catalyst has been completely marketed after decades of research by engineering technicians in various countries, and the cost is greatly reduced as the technology is mature day by day. The price of high-end commercial ternary purifiers has dropped below $ 50. However, the direct use of commercial purifiers still requires some attention to problems and modifications. The detailed description is as follows:

(1.1) the so-called catalytic converter for vehicle converts CO, hydrocarbons and nitrogen oxides in exhaust gas into those which are harmless to human body by the action of catalystAn exhaust gas purifying apparatus for a harmful gas. Oxidation catalytic converters developed decades ago can only oxidize CO and hydrocarbons in the exhaust gas to CO₂And H₂O, and therefore such a catalytic converter is also referred to as a two-way catalytic converter. Binary catalytic converters have been currently eliminated due to their inability to convert nitrogen oxides. But the knowledge about its catalytic technology and product manufacturing process remains intact and most patents have expired. And so can be directly adopted by the present invention.

(1.2) according to the existing binary catalytic technology, the oxidation catalysts used in the binary catalytic converter used in this step are platinum (Pt) and palladium (Pd).

(1.3) in order for the two-way catalytic converter to operate properly, it is necessary to supply secondary air as an oxidant to make up for the shortage of oxygen content in the exhaust gas. However, if used for the purification of air VOCs, no additional oxygen is required, and the oxygen and the ozone which is additionally produced in the gas stream are sufficient to ensure complete oxidation. The secondary air intake component can be omitted.

(1.4) the catalytic converters for vehicles all adopt carriers made of honeycomb ceramic materials (such as cordierite and aluminum oxide), and catalyst active component coatings such as Pd, Rh and the like are attached to the carriers. The ceramic carriers with various shapes contain higher-density airflow channels (the aperture ratio can reach 400 meshes/inch)²Above, the minimum wall thickness can reach below 0.16 mm), so as to reduce exhaust resistance and prevent the normal operation of the engine from being influenced by overhigh back pressure of the converter. The invention can reduce the airflow resistance by directly adopting the carrier of the vehicle catalytic converter, and the purified air flow is far larger than that of the filtering type air purifier.

(1.5) the catalytic converter for vehicle must withstand high exhaust temperatures (generally higher than 300 ℃), so stainless steel is required as a housing, and a gasket between the two is made of a temperature-resistant material such as ceramic fiber and vermiculite. The temperature of the purified air is generally room temperature. Heavy metal casings and complicated liner materials are omitted. To this end, the converter manufacturer may be required to change the manufacturing process to produce the desired oxidation catalyst specifically for the air purifier.

(1.6) since the gas flow of the step contains a large amount of active substances and excessive ozone generated in the previous step, and the auxiliary effect of the ultraviolet lamp injected into the carrier gas flow channel, the oxidation process of VOC generated on the surface of the catalyst molecules can be fully performed at room temperature without the onset temperature (250-350 ℃) required by the catalytic conversion of the traditional vehicle. And as the reaction proceeds, the heat generated by oxidation gradually increases the temperature of the gas flow, and the oxidation reaction rate is accelerated.

(2) Catalyst duration, catalyst length and airflow velocity range

And the length of the two-way catalytic converter is 110-250mm, the residence time of the tail gas in the two-way catalytic converter can be calculated to be not more than 0.002 s. When used for air purification, the length of the oxidation catalyst purifier is only 40mm at an air flow rate of 2m/s, considering that the air flow temperature is low, even if the catalytic time is extended by 10 times (0.02 s). The length of the oxidation catalyst employed in the present invention is in the range of 40-100mm, and the suitable gas flow rate is in the range of 1-5 m/s.

(3) Temperature and humidity

As previously mentioned, the temperature of the gas stream passing through the oxidation catalyst may be controlled between 20-65 ℃. Too low or too high a temperature is not favorable for the ultraviolet photolysis efficiency. When the humidity of the air flow is high, the inactivation of the virus is facilitated, and in the occasions (such as hospitals, toilets or public activity places) where the virus needs to be mainly purified, the relative humidity can be increased to more than 70% by increasing the moisture in the air flow. Methods of adding moisture include, but are not limited to, ultrasonic humidification or water heating evaporation.

(4) Ultraviolet light source

The wavelength range of the ultraviolet lamp is between 185-375nm, the purification efficiency is higher at shorter wavelength, the efficiency is poorer at longer wavelength, but the ozone amount and the oxidation by-products are less.

5. Reduction catalytic treatment

Ozone is a second-site strong oxidant known by human beings and only second to fluorine, and ozone can generate biochemical oxidation reaction with microorganisms such as bacteria, viruses and the like under a certain concentration and can be used as a high-efficiency sterilization disinfectant. Domestic ozone is used for air intake in sickrooms, operating rooms and other placesThe sterilization and disinfection are the main popularization directions. But the ozone concentration must be reduced to the national allowable concentration (0.2 mg/m) in the room after disinfection³) In the following, personnel can enter. Therefore, the indoor residual ozone needs to be rapidly purified. The treatment method mainly includes catalytic decomposition, thermal decomposition, and activated carbon adsorption. The thermal decomposition method has high energy consumption and high requirements on the reactor. The activated carbon adsorption process produces unstable ozonated products, the absorber is prone to combustion and explosion, and the adsorbent needs to be replaced frequently. The catalytic decomposition method adopts transition metal oxides such as manganese, cobalt, copper and the like and rare earth metal oxides to form an ozone decomposition catalyst, and can play a role in catalytic decomposition of ozone at normal temperature. One current theory that is reasonable is: ozone first contacts with the surface of the catalyst and is adsorbed on the active sites of the catalyst to produce an oxygen molecule and a surface active oxygen atom, and then the oxygen atom is combined with other ozone molecules to produce two oxygen molecules. The method has the advantages of low equipment investment and low operation energy consumption. The present inventors believe that ozonolysis is the process by which ozone molecules lose oxygen atoms, essentially a reduction reaction, requiring a catalyst different from the oxidation catalyst. Just as the three-way catalytic converter for a vehicle differs from the two-way converter. The latter catalyst has platinum (Pt) and palladium (Pd) to catalyze the oxidation reaction of hydrocarbon and CO. The former adds rhodium (Rn) and can catalyze the reduction reaction of nitrogen oxide. The present invention can directly use a three-way catalytic converter for vehicles to promote the reduction of ozone, in addition to the conventional reduction catalyst. The inventors' experiments have shown that this concept works well, but there are still some problems to be noticed. The description is as follows:

(1) catalyst arrangement sequence

According to early studies, a three-way catalytic converter for a vehicle can reduce nitrogen oxides NOx to nitrogen (N) using CO and hydrocarbons in exhaust gas as reducing agents₂) And oxygen (O)₂) In the reduction reaction, CO and hydrocarbon are simultaneously oxidized into CO₂And H₂And O. When both converters are used simultaneously, the three-way catalytic converter is usually placed in front of the two-way catalytic converter. The exhaust gas is first passed through a three-way catalytic converter to remove nitrogen contained thereinAfter the oxide is reduced, the oxide enters the binary catalytic converter, and the residual CO and hydrocarbon compound which are not oxidized continue to carry out oxidation reaction with the oxygen in the secondary air.

However, in the present invention, the oxidation catalyst is placed in front of the reduction catalyst for the following reasons:

(1.1) the invention is used for air purification but not locomotive exhaust purification, the concentration of nitrogen oxide in the air is very low, VOC is mostly hydrocarbon and oxygen compound, the pollutant needing to be reduced is mainly ozone, and the invention needs ozone to oxidize VOC under the condition of room temperature, so a certain ozone concentration is ensured firstly, and redundant ozone is reduced finally.

(1.2) As mentioned above, according to the ozone catalytic decomposition theory, no other reducing agent is needed for reducing ozone, and two molecules of ozone can be reduced into 3 molecules of oxygen under the action of the catalyst. So that the ozone treatment is left in the last step without the problem of insufficient reducing agent.

(1.3) under normal conditions, a large amount of heat is generated in the oxidation reaction, a higher temperature is required in the reduction reaction, and ozone can be rapidly decomposed into oxygen at 200 ℃. In most of the normally working oxidation catalytic converters, the temperature of the outlet airflow is about 20-25% higher than that of the inlet airflow. The oxidation catalyst is arranged before the reduction catalyst, so that heat generated by the oxidation reaction is favorably brought into the reduction reaction, and the decomposition of ozone is accelerated.

(2) Increasing the catalytic temperature

In addition to utilizing the heat generated by the oxidation conversion in the previous step, it is also desirable to try to increase the temperature of catalytic reduction of ozone where the residual ozone concentration is high. The invention adopts the following measures to heat the catalyst per se:

(2.1) heating the reduction catalyst by using heating air flow or fuel gas and coal-fired exhaust flue gas;

fig. 7 shows a winter heating system commonly used in rural areas, in which high-temperature flue gas generated by a coal-fired furnace is discharged to the outside of a room through a chimney pipe penetrating the room, and heat of the high-temperature flue gas is transferred to indoor air in the form of radiation and convection through a metal casing of the pipe. Although simple and practical, the greatest problem of the winter heating system is the risk of CO poisoning. In order to isolate cold outdoor air, people are used to close doors and windows at night, so that oxygen in the room is insufficient, fuel cannot be combusted fully, a large amount of CO is generated, and people are poisoned in sleep. If the air cleaning apparatus of the present invention is employed, various benefits can be obtained:

1) CO generated by the coal-fired furnace is fully oxidized into CO in the oxidation catalytic purifier 6 after entering the purification system₂Effectively eliminating the poisoning risk;

2) compared with fuel oil and natural gas, coal has high impurity content, and generates a large amount of toxic VOC after combustion. These VOCs can be purified in the corona field processor 3, oxidation catalytic purifier 6, reduction catalytic purifier 7;

3) because the heating furnace is directly arranged indoors, under the condition of higher combustion temperature, nitrogen oxide which is not common in urban heating can be generated. These contaminants can be reduced to nitrogen and oxygen in the reduction catalytic converter 7;

4) the coal combustion value is not high, a large amount of ash generated after combustion can be left indoors, the content of particulate matters in air is increased violently, and most of the particulate matters can be collected in the cold plasma generator 2 and the magnetic field generator 8 after the purification system is adopted;

5) in order to improve the catalytic efficiency of the reduction catalyst, the reduction catalytic purifier 7 is placed in a smoke exhaust pipeline (but is isolated from the smoke), and the reduction catalyst is heated by high-temperature smoke.

For an urban heating system adopting central heating, the reduction catalytic purifier 7 can be placed in the discharged heating (but isolated from the heating) or placed around the radiator to play a role in heating the reduction catalyst.

(2.2) communicating the air inlet and outlet of the air conditioning system

Determining a communication mode according to the working property of the air conditioning system:

1) under the condition that the air conditioning system blows out warm air in winter, the warm air is used as the inlet air of the purification system to improve the efficiency of ozone reduction and decomposition;

2) and under the condition that the air conditioning system blows out cold air in summer, the air outlet of the purifier is used as the air inlet of the air conditioning system, so that the reduction of the ozone reduction decomposition efficiency is avoided.

(2.3) heating the catalyst by resistance heating

The electric heating wires are arranged inside and outside the reduction catalyst, and the catalyst is directly heated by an electric heating mode, so that the efficiency of ozone reduction decomposition is improved.

(2.4) heating the catalyst by means of infrared

The catalyst was reduced by heating with an infrared lamp. The method is simple and does not influence the structure of the catalyst. But still two points of attention need to be paid:

1) selection of infrared wavelength: in order to improve the heating efficiency, it is necessary to make the radiation wavelength of the infrared heater substantially coincide with the absorption wavelength of the material to be heated. For this purpose, the effective absorption wavelength range of the reduced catalyst support material must first be determined. According to the report of the literature, the nano Al₂O₃The carrier is at 450-1000cm^-1Has a broad infrared absorption band in the wavenumber range of (a), which is called its characteristic absorption band. The absorption wavelength converted range is 10 to 22.28. mu.m. Therefore, the invention adopts a far infrared lamp with the wavelength ranging from 8 to 25 mu m to heat the reduction catalyst.

2) The installation method of the infrared lamp comprises the following steps: the infrared light was irradiated parallel to the gas flow channel of the catalyst. The infrared ray is emitted to the deep inside of the catalyst through the airflow channel.

(3) Catalyst time, catalyst length and gas flow rate

The length of the reduction catalyst used in the present invention is in the range of 40 to 100mm, and the gas flow rate is suitably in the range of 1 to 5 m/s.

6. Simplification of air purification step

The above 5 steps are suitable for air purification of high-concentration particulate matters, high-concentration VOC, high-lethal viruses and high-concentration ozone. For the special case that the concentration of pollutants is lower, the steps can be simplified so as to reduce the volume of equipment, improve the practicability, save the energy consumption and reduce the cost. Generally, when the concentration of particulate matter is high, the VOC concentration is also high, so the following cases are simplified:

1) the particulate matter concentration is very low, the VOC concentration is high, and the situation that dangerous germs and viruses are possibly contained is avoided

The corona field treatment step can be omitted while the static magnetic field in the cold plasma treatment is cancelled. As shown in fig. 8, positive and negative ions generated from the cold plasma generator 2 charge viruses and germs before entering the positive and negative corona fields, and after entering the corona fields, the charged germs and viruses are expelled by corona wires to the surface of the dust collecting electrode and inactivated by discharge. The VOC in the air flow is decomposed by the corona and ultraviolet rays, and then is completely oxidized after entering the oxidation catalytic converter 6, and the residual ozone is reduced in the reduction catalytic converter 7.

2) Low particulate matter and VOC concentrations, but air may contain dangerous germs and viruses

The corona field treatment step and corona synergistic ultraviolet light treatment step of the present invention can be omitted, as shown in fig. 9, positive and negative ions generated by the cold plasma generator 2 charge germs and viruses before entering the oxidation catalytic purifier 6, and after entering the oxidation catalytic purifier 6, the charged germs and viruses discharge on the surface of the catalyst, and the surface protein structure is inactivated by oxidation damage under the multiple actions of the catalyst, ozone generated by the cold plasma generator 2 and the second ultraviolet lamp 9. The VOC in the air stream is decomposed by both corona and uv light. The residual ozone is reduced in the reduction catalytic converter 7.

7. Experimental verification

The invention adopts corona field to remove particles, which is a mature technology in the industry and has undoubted effect. But the removal effect of VOC and ozone needs to be experimentally verified. The inventors monitored 5X 3m using an Air Quality monitor (HTO-132 Air Quality Detector master by Hytop Innovation and Technology Co., Ltd.)³The air quality in the room after the prototype treatment of the invention is changed. As shown in fig. 10, the units of the contaminant parameters in the graph are as follows: HCHO (mg/M)³),TVOC(10mg/M³),PM2.5(ug/M³),PM10(ug/M³),CO(ppm),CO₂(100ppm)。

From the experimental results, the concentrations of the various pollutants were reduced to different degrees within 120 minutes: PM10 decreased from 35ug/L to 8ug/L, HCHO from 25mg/M³Reduced to 15mg/M³TVOC is 150mg/M³Reduced to 90mg/M³The CO was reduced from 10ppm to 6 ppm. Because the experimental prototype only adopts the cold plasma treatment step and the corona field treatment step, the reduction of the particulate matters is obvious, and the reduction of VOC and CO is not obvious.

Figure 11 uses a prototype comprising a cold plasma treatment step and an oxidative catalytic treatment step to treat artificial VOCs containing 70% ethanol. Wherein the oxidation catalyst directly adopts a vehicle binary catalyst. Experiments show that the VOC purifying effect is very obvious under the synergistic action of plasma and oxidation catalysis.

5X 3m was monitored using an Ozone monitor (gradient: I2C Ozone Sensor and Arduino Romeo V1.3 analog circuit) t³The concentration of ozone in the room after the treatment by the prototype of the invention (room temperature 25 ℃, humidity 55%) was determined.

FIG. 12 shows the results of treating high concentrations of ozone generated by a dielectric barrier ozone generator (ozone amount 5g/h) by a reduction catalytic treatment step. Wherein the reduction catalyst adopts a three-way converter for vehicles. Experiments have shown that although the ozone concentration in the first 70s room rises sharply, it begins to drop rapidly thereafter, although not reaching the standard, because the original ozone concentration in this experiment is far beyond that of real-life air.

FIG. 13 is a graph showing the relationship between ozone concentration and time after a cold plasma treatment step and a reduction catalyst treatment step in a prototype according to the present invention. The bipolar plasma generator adopted in the cold plasma treatment step is a product of XX company of America (D1.2-1cold plasma, power supply 115VAC), and the reduction catalysis treatment step directly adopts a three-way catalytic converter for vehicles. It is clear from the figure that the reduction catalytic treatment step enables the concentration of ozone generated by the cold plasma treatment step to be rapidly reduced and reach the standard, which is sufficient for the effectiveness of the technology of the present invention.

The above examples are only for describing the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An air purification device, characterized in that includes in proper order along the air flow direction:

the cold plasma generator (2) is connected with the high-voltage generator, positive and negative ions are emitted into air flow to be purified by the cold plasma generator (2), the active substances generated by the cold plasma generator (2) carry out primary conversion and decomposition on gaseous pollutants, and particles in the air flow become charged particles after the positive and negative ions are adhered to the particles;

the oxidation catalytic purifier (6) thoroughly oxidizes and decomposes the gaseous pollutants into carbon dioxide and water, and destroys protein structures on the surfaces of microorganisms and viruses;

and the reduction catalytic purifier (7) is used for reducing redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the gas flow into oxygen, nitrogen, carbon dioxide and water.

2. The air cleaning apparatus according to claim 1, further comprising, for air with a high concentration of gaseous pollutants:

the static magnetic field generator (8) is arranged between the cold plasma generator (2) and the oxidation catalytic purifier (6), the direction of the static magnetic field generated by the static magnetic field generator (8) is vertical to the direction of the airflow or vertical to the movement direction of the charged particles in the airflow, and the static magnetic field generated by the static magnetic field generator (8) can gather the particles with opposite charges in the airflow;

and a corona field processor (3) connected with the high voltage generator, wherein the corona field processor (3) is arranged between the static magnetic field generator (8) and the oxidation catalytic purifier (6), the corona field processor (3) comprises a positive corona field and a negative corona field which are arranged in parallel, the positive corona field collects the residual positively charged particles in the air flow, the negative corona field collects the residual negatively charged particles in the air flow, the particles collected by the static magnetic field generator (8) are charged again through the positive corona field and the negative corona field and are attracted and collected by the corona field collecting electrodes with different charges, and the active substances generated by the positive corona field and the negative corona field carry out secondary conversion and decomposition on the gaseous pollutants.

3. The air cleaning apparatus according to claim 2, characterized in that: slit or hole (4) have been seted up to the exit end of corona field treater (3), the surface of the collection dirt utmost point of corona field treater (3) still is equipped with first ultraviolet lamp (5), the ultraviolet ray of first ultraviolet lamp (5) passes slit or hole (4) and shines on the corona field filament in corona field treater (3), the synergism of corona field treater (3) and first ultraviolet lamp (5) carries out the third time conversion with gaseous pollutant and decomposes, and first ultraviolet lamp (5) can be to carrying out the ultraviolet inactivation processing because of the small residual virus that is not collected by corona field treater (3) and handles in the air current simultaneously.

4. The air cleaning apparatus according to claim 1, characterized in that: the outlet end of the oxidation catalytic purifier (6) is also provided with a second ultraviolet lamp (9), and the residual gaseous pollutants in the air flow are thoroughly oxidized into carbon dioxide and water under the synergistic action of the oxidation catalytic purifier (6) and the second ultraviolet lamp (9).

5. The air cleaning apparatus according to claim 1, characterized in that: the outlet end of the reduction catalytic purifier (7) is also provided with a far infrared lamp (10) for increasing the reduction catalytic temperature.

6. The air cleaning apparatus according to claim 2, characterized in that: the positive corona field air inlet of the corona field processor (3) is close to the positive ion emitting electrode of the cold plasma generator (2), and the negative corona field air inlet of the corona field processor (3) is close to the negative ion emitting electrode of the cold plasma generator (2).

7. The air cleaning apparatus according to claim 1, characterized in that: the oxidation catalytic purifier (6) adopts a binary catalyst in a motor vehicle, and the reduction catalytic purifier (7) adopts a three-way catalyst in the motor vehicle.

8. An air cleaning method, which is implemented by the air cleaning apparatus of any one of claims 1 to 7, comprising the steps of:

firstly, emitting positive and negative ions into air flow to be purified by adopting an ion emitting electrode of a cold plasma generator (2), and carrying out primary conversion and decomposition on gaseous pollutants by using active substances generated in the process; respectively adsorbing positive and negative charges on the particles in the airflow to form charged particles;

secondly, the airflow treated in the first step passes through an oxidation catalytic purifier (6) to thoroughly oxidize and decompose the gaseous pollutants into carbon dioxide and water, and simultaneously destroy the protein structures on the surfaces of microorganisms and viruses;

and step three, the airflow treated in the step two passes through a reduction catalytic purifier (7) to reduce redundant ozone, a small amount of nitrogen oxides and residual gaseous pollutants in the airflow into oxygen, nitrogen, carbon dioxide and water.

9. The air purification method according to claim 8, characterized in that: for air with higher particulate matter concentration, in the first step, after the charged particulate matter is formed, the particulate matters with opposite charges are close to each other by utilizing the dual functions of coulomb force between positive and negative charges and Lorentz force generated by a static magnetic field generator (8), and are aggregated and grown after collision contact discharge; and also let the airstream pass the corona field processor (3), make the residual particle matter with positive charge in the airstream collect through the positive corona field, the residual particle matter with negative charge in the airstream collects through the negative corona field, have lost the electric charge and gather the long particle matter and pass the positive corona field or the negative corona field and charge again, then attract by the dust-collecting electrode with different electric charges and collect, meanwhile, the active material that the positive corona field produces carries on the second conversion to decompose to the gaseous pollutant.

10. The air purification method according to claim 9, characterized in that: and blowing the ozone and the active substances generated by the dielectric barrier discharge ionizer into the air flow in the step one, so that the ozone and the active substances are additionally added into the air flow on the basis of the ozone and the active substances generated in the step one.