WO2007138172A1

WO2007138172A1 - An apparatus and a method for purifying a material flow

Info

Publication number: WO2007138172A1
Application number: PCT/FI2007/050317
Authority: WO
Inventors: Niklas TÖRNKVIST; Ari Ahola
Original assignee: Biozone Scientific International Oy
Priority date: 2006-05-31
Filing date: 2007-05-31
Publication date: 2007-12-06
Also published as: FI20065367A0; FI20065367L

Abstract

The invention relates to an apparatus (3-40, 4-40, 5-40) and a method for purifying a material flow (4-35, 4-36, 5-35, 5-36), particularly air, gas or liquid. It comprises a first source of radiation in form of a lamp (3-50, 4-50, 5-50) generating a first UV radiation containing at least one of wavelengths of approximately 187 nm and 254 nm, and a housing surrounding the lamp (3-50, 4-50, 5-50) and confining a flow path between the lamp (3-50, 4 -50, 5-50) and the housing for the fluid to be purified by said first radiation. In the invention, furthermore, a second source of radiation is provided in form of a layer (3-25, 4-37, 4-38) containing fluorescent component and arranged apart from the lamp (3-50, 4-50, 5-50), said fluorescent component being reactive to said first UV radiation emitted by the lamp to generate a second UV radiation containing at least one wavelength in the range of about 300 to 385 nm, and a catalytic material reactive to the second UV radiation to produce photo catalytic oxidation, preferably hydroxyl radicals, to the flow path.

Description

An apparatus and a method for purifying a material flow

Field of the invention

The present invention relates to an apparatus and a method for purifying a material flow, and more particularly to ultraviolet light purifiers.

Background of the invention

Ultraviolet light (UV light, uviol light) is devided into specific subclasses. When considering the effect of UV light on human health and the environment, UV radiation is often subdivided into UVA, UVB and UVC wavelenghts. The UVA light is also called the longwave or blacklight, as it is invisible to the human eye. Its wavelenght varies between about 315 to 380 nm. UVB has the wavelenght of 280 to 315 nm and UVC has the wavelenght smaller than 280 nm.

Fluorescent lamps emit light, because electrons passing through the light tube collide with the electrons of the gas in the tube causing them to move into higher orbits. When they return to their initial state of energy, they give out the excess energy in the form of photons. The wavelength of a photon is determined by the particular electron arrangement in the atom. The electrons in mercury atoms are arranged in such a way that they mostly release light photons in the ultraviolet wavelength range. Moreover, the fluorescent coating on the inside of the tube can absorb the higher energy (equalling with lower wavelength) light and transfer it back on a higher wavelength (equalling with lower energy) thus converting the wavelength into visible light or to the other required wavelength.

When some living cells absorb UV radiation, they can be destroyed as a result of the chemical reactions produced by the ionisation and dissociation of their molecules. For that reason UV rays can be used in medical applications and also in sterilization processes in which microorganisms, such as bacteria, may be killed. A known application is UV light air purifier, which is used to free air from contaminants. These set-ups include germicidal UV light and the emission of ions into the air to react with contaminants and making them harmless.

Fig. 1 shows a standard fluorescent lamp 1 -40 with the light of 365 nm. It has two electrodes 1-2, 1 -4 and mercury (Hg) vapour and argon (Ar) gas 1-10 inside of the tube 1 -6, 1-8. The tube is a highpass filter glass or a fluorescent bandpass filter glass filtering all wavelengths that are above 260 nm. The inside 1 -12, 1-13 of the tube is coated by fluorescent material. Fig. 1 also shows two plugs 1 -14, 1 -16 for retaining the vapour and gas inside the tube and two wires 1 -18, 1 -19 for leading the electricity to the structure. When the lamp is in function a drop of mercury gasifies due to the electric discharge and generates UV radiation. The light emits two wavelengths, namely 254 nm and 187 nm, which are transformed and filtered into 365 nm by the fluorescence coating inside of the tube. The wavelength of 365 nm is important in air purifiers, because it kills bacteria.

The lamp of Fig 1 can be used as an air purifier, but it is expensive and it does not emit the desired light of 254 nm outside of the lamp in amounts that is required. This is due to the used 260 nm highpass filter glass or a fluorescent bandpass filter glass structure 1-6, 1 -8.

The light of 187 nm that shines on oxygen (O2) breaks up the O2 molecular bonds and generates ozone (O3). Ozone is very reactive and can destroy e.g. fungi and mould. Furthermore, it can kill bacteria and break some molecular bonds of some compounds. O3 has a half time, a period of decay of roughly 6 minutes in normal indoor conditions meaning that O3, when generated inside of the air purifier, can cause the purifier to act as an ozone-transmitting device. O3 can then work outside the cleaner in the room it is used in, provided that the ozone levels sent out from the purifier are proportioned to the size and the ventilation speed of the room.

The light of 254 nm wavelength kills bacteria and thus it can be used for sterilizing purposes, e.g. for sterilizing surgical equipment in hospitals. Airborne bacteria that are transported through the purifier will be killed. The level of bacterial purification depends largely on the exposure time, i.e. the time the contaminated air is exposed on said wavelength, and the intensity of the light, i.e. the amount of radiation. The more intense the light is, the stronger the bacteria are exposed to this light and the more efficient the purification is, because more light and time equals more dead bacteria. Figure 2 shows a fluorescent lamp 2-40 with a conventionally used mercury vapour light tube 2-6, 2-8. The tube can be of a quartz glass that passes through light with wavelengths of 187 nm or more, i.e. UVA, UVB and UVC light. Inside 2-12, 2-13 of the tube there is no coating, e.g. no fluorescent coating for allowing the lamp to give light. The light generated by the lamp of Fig. 2 is commonly used in indoor air purifiers for sterilizing purposes. This light emits two wavelengths of interest, namely 254 nm and 187 nm. The stronger the 254 nm emission peak of this light is, the stronger its germicidal effects are. However, the lamp does not emit the desired wavelength of 365 nm.

Some known purifying apparatuses also comprise photo catalytic material, e.g. titanium dioxide (TΪO2), which is excited by a UV radiation to produce hydroxyl radicals (OH^") to provide further purification. Examples of such apparatus are disclosed in US patents 6,761 ,859; 6,884,399; 6,913,637; 5,835,840; 6,501 ,893; 6,589,489; and 6,773,682; and in US patent application publications 2005/0063881 ; 2005/0129591 ; 2005/0191219; 2005/0244309; 2005/0238551 ; and 2005/0201907.

The disadvantage with the known lamps is that if one wishes to generate the 360 nm light, the lights of 254 nm and 187 nm become weak. On the other hand, the lamp, which produces lights of 254 nm and 187 nm, cannot produce the 360 nm light. Thus, to be able to purify the air efficiently, two or more light sources must be provided according to known systems making the systems large, complicated and expensive.

US Patent 6,797,127 discloses an apparatus for purification of oxygen-containing gas. The apparatus comprises three consecutive departments. Each department is provided with a lamp radiating ultraviolet rays of different ranges of wavelengths, namely 110-200 nm, 200-300 nm, and longer than 300 nm. Two of departments comprise photo catalyst coating, such as titanium oxide coating.

Brief disclosure of the invention

An object of the present invention is to provide a method and an apparatus for implementing the method so as to alleviate the above disadvantage. The objects of the invention are achieved by an apparatus and a method, which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims. An apparatus for purifying a material flow, particularly air, gas or liquid, comprises a first source of radiation in form of a lamp generating a first UV radiation containing at least one of wavelengths of approximately 187 nm and 254 nm. A housing surrounds the lamp and confines a flow path between the lamp and the housing for the material flow to be purified by said first radiation. A second source of radiation in form of a layer is arranged apart from the lamp and contains fluorescent component, which is reactive to said first UV radiation emitted by the lamp to generate a second UV radiation containing at least one wavelength in the range of about 300 to 385 nm. Further, the apparatus comprises a catalytic material reactive to the second UV radiation to produce photo catalytic oxidation, preferably hydroxyl radicals, to the flow path. In an embodiment of the invention, the second source of radiation and the catalytic material are formed on a common substrate. In another embodiment of the invention, the second source of radiation is formed on the inner surface of the housing.

In a further embodiment of the invention, the second source of radiation and the catalytic material are formed as a porous filter structure located between the first source of radiation and the housing to divide the flow path into department, so that the material to be purified is adapted to flow from one department to another through said porous filter structure.

In a still further embodiment of the invention, the second source of radiation and the catalytic material are formed on a common substrate, which folded several times along the longitudinal axis of the lamp forming the first source of radiation.

In an embodiment of the invention, the axis of the flow path is substantially parallel with the longitudinal axis of the lamp forming the first source of radiation.

According to a further embodiment of the invention, the second source of radiation and the catalytic material are formed on a common substrate having a star-like cross sectional profile in the longitudinal axis of the lamp forming the first source of radiation. The axis of the flow path may be substantially tangential to the longitudinal axis of the lamp forming the first source of radiation.

In an embodiment of the invention, the catalytic material and the fluorescent component are constructed layer wise and/or the fluorescent material is distributed within the catalytic material. According to an embodiment of the invention, the second UV radiation contains particularly the wavelength of about 365 nm.

According to an embodiment of the invention, the catalytic material comprises one or more of: photo catalytic material, TΪO2, aluminium, copper, or any other material that can act as a catalyst and generate hydroxyl radicals. According to an embodiment of the invention, the first source of radiation is a mercury-argon light tube. According to an embodiment of the invention, the layer containing fluorescent component is painted and/or printed and/or etched and/or soldered and/or filmed and/or evaporated and/or sputtered.

According to an embodiment of the invention, the apparatus further comprises a negative ion generator.

The invention is based on the idea of providing at least one wavelength in the range of about 300 to 385 nm outside of a lamp, which provides the wavelengths of approximately 187 nm and 254 nm. Thereby, the wavelength in the range of about 300 to 385 nm, and consequently, OH^" radicals can be produced, without having any detrimental effect on the wavelengths of approximately 187 nm and 254 nm. All required wavelengths can be generated with one lamp.

An advantage of the method and arrangement of the invention is a very simple lamp arrangement structure.

Brief description of the drawings

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figure 1 is a schematic picture of a conventional fluorescent lamp; Figure 2 is a schematic picture of a conventional fluorescent lamp;

Figure 3 is a schematic picture of one embodiment of the present invention;

Figure 4 shows one embodiment of the present invention;

Figure 5 shows one embodiment of the present invention; Figure 6 shows one embodiment of the present invention; and

Figure 7 shows one embodiment of the present invention.

Detailed description of the invention

In the present invention and its embodiments all wavelengths and other magnitudes or quantities mentioned disclose certain numerical wavelength or value. It is to be understood that they only are examples. Thus also certain range around them is disclosed, and e.g. the wavelength can have said value or a value smaller or greater than the written value. Thus, e.g. the wavelength of 365 nm can also represent the wavelength of 356nm, 360 nm, 366 nm and/or 370 nm, as long as the wavelength fulfil its function(s). As another example, if ozone is produced or is to be produced, it is the ozone wavelength(s), the end product, that is disclosed independent of the exact value(s). The presentation of value(s) is made more like on a sliding scale than as a step function(s).

Figure 3 shows one embodiment according to the invention and its embodiments. The lamp 3-50 may be e.g. a conventional lamp of the type as described in connection with Figure 2, thus benefiting from the easily controllable light of about 187 nm and the maximal output of the germicidal about 254 nm peak. For example, the lamp 3-50 may be a mercury-argon discharge light tube. It has two electrodes 3-2, 3-4 situated in the tube 3-6, 3-8. The electrodes can be opposite to each other as shown, but they can also be situated e.g. adjacent to each other. Various other configurations of the electrode(s) and the tube itself are also possible. The tube can be e.g. circular, square or arc-like. There can be one or more electrons provided in the tube. The plugs 3-14, 3-16 can retain vapour and/or gas 3-10 inside the tube. The material of the tube can be of quartz glass 3-12, 3-13 filled with mercury vapour and argon gas. However, instead of mercury, any material that can be in vapour and produce light with different wavelengths can be used. Instead of argon, krypton (Kr), neon (Ne), xenon (Xe) or other gases can also be used for controlling the electric conductivity and the ignition and the electric discharging.

What is important for the material of the tube is that it can pass through the light of different wavelengths. These wavelengths can comprise the light of 187 nm and/or light with higher wavelengths. The lamp can be coated or constructed in such a way that the output of the O₃ generating wavelength can be controlled and thus the generation of ozone can be controlled and/or that the passing of the 254 nm wavelength is not controlled . The material of the tube can be transparent and/or semitransparent for said wavelengths, e.g. lithium fluoride. It is also possible to use said material only in some parts of the tube and/or cover wholly or partly the tube with said material. In one embodiment, there is no coating on the inside 3-12, 3-13 of at least one part of the tube 3-6, 3-8 and thus photons with different wavelengths, e.g. of 254 nm can pass through 3-20 the glass.

In an embodiment, at least part of the lamp is surrounded by a layer 3-25 that can comprise photo catalytic material, e.g. titanium dioxide (Tiθ2,) and a fluorescent compound. Instead of or in addition to Tiθ2 or any other catalyst can be used that can generate photo catalytic oxidation. Thus, catalytic material can comprise one or more of: photo catalytic material, TΪO2, aluminium, copper, or any other material that can act as a catalyst and generate hydroxyl radicals. The fluorescent material, which can be e.g. in powder form, can be distributed with the TΪO2 or it can be separately coated close to it. The layer 3-25 can be constructed in many ways e.g. in layers or such that Tiθ2 and the fluorescent compound are mixed together or that they exist alone or mixed with a third material from layer to layer. The layer can also be so constructed that on one side of the layer is titanium and on the other side is the fluorescent component. Also other substrates than the Tiθ2 substrate can be used. Examples of these are aluminium and copper. The composition of the fluorescent material in the fluorescent layer can also be changed e.g. according to the quality and tone of the different wavelengths and the desired function.

Tiθ2 can be said to be first material in the layer and the fluorescent compound can be said to be the second material of the layer, although they do not have to be in any specific order in the layer or they do not have to form any layer like layer. The thickness of the titanium layer can be varied for each application. It can also be so thin that the titanium layer is transparent or semi transparent. This is especially in applications where titanium is coated onto the tube or inside of it and the fluorescence is made in the tube. In one embodiment of the invention Tiθ2 is the base material of the layer, into which the fluorescent component is introduced. The amount of titanium can vary from about 10% to 90%, e.g. from about 20% to 80%, or from about 30% to 63%, or from about 40% to 48% of the base material. It can be e.g. 8.9 %, 10%, 15%, 23%, 35%, 40%, 42%, 46%, 48%, 50%, 62%, 77%, 81 %, 89% or 91 % of the base material.

When the radiation of about 254 nm hits and/or passes through the layer comprising Tiθ2 and/or the fluorescent compound, a chemical fluorescence reaction can absorb the about 254 nm light photon and emit the about 360 nm light photon. After that or substantially simultaneously the light of about 365 nm can hit the titanium material or the layer comprising e.g. titanium producing hydroxyl radicals (OH^" radicals) and causing photo catalytic oxidation (PCO). Thus, when e.g. air and/or other gas and/or fluid and/or water contaminated with organic material becomes in contact with said radicals, the organic material will be oxidized and the contaminated air and/or fluid and/or water will become decontaminated from the organic compounds. In these reactions the bonds between the atoms are broken and carbon dioxide and water vapour is generated. The contact of said contaminated organic material with said radicals can be affected on the surface of the TΪO2 layer or in its vicinity.

In addition to using hydroxyl radicals for decontamination, also the light of a first wavelength, namely the light of about 295 nm to 390 nm or to even 420, preferably about 340 nm to 388 nm, more preferably of about 385 nm or about 365 nm or about 360 nm or 340 nm, the light of a second wavelength, namely the light of about 220 nm to 280 nm, preferably about 245 to 260, more preferably about 250 nm or about 254 nm or about 256 nm and the light of a third wavelength (a further wavelength), namely the light of about 170 nm to 220 nm, preferably about 182 nm to 189 nm, and more preferably about 183 nm or 184 nm or 185 nm or 186 nm or 187 nm or 188 nm or 189 nm or at least one of these wavelengths can be used for purifying and cleaning purposes. This is due to the fact that the light of about 340 nm to 385 nm can be generated outside of the lamp itself. In other words, the about 360 nm light can be generated without reducing the amount of the 254 nm light and this can thus maximize the 254 nm light shining out from the source, e.g. the lamp, because it is not filtered out e.g. by the fluorescent coating of the layers 1 -12, 1 -13 of the tube 1 -6, 1-8 in Figure 1. Also other wavelengths can be generated inside and/or outside of the tube thus making the purification even more effective.

The light of a first wavelength can also be defined to be the light under about 385 nm.

In Figure 3, the generation of hydroxyl radicals is made outside of the lamp on the Tiθ2 surface by means of the fluorescence. It must be noted however that the fluorescence can also be made on the tube or in its vicinity by bringing titanium material into the fluorescence material at least partly coating the tube. In this case hydroxyl radicals are formed on the tube itself or near to it.

As described above, the UV light of interest that has wavelengths between about 340 to 385 nm and that shine on Tiθ2 or substrate of other material can produce hydroxyl radicals (OH^"). These are among the most reactive radicals of all and can very efficiently break up volatile organic compounds (VOC). Mercury vapour will not, however generate any significant amounts of light of this wavelength, which means that it has to be produced by some other means. The solution for this is to produce the light of these wavelengths by a fluorescence compound placed outside of the glass tube, which compound can be excited by the strong 254 nm light from mercury emission and that emits at the wavelength of 365 nm.

The light of 365 nm for the PCO can also be generated on the TΪO2 surface itself. This arrangement has the benefit that the fluorescence effect does not interfere with the other wavelengths of light, thus maximising the other wavelengths. As a special advantage, the wavelength of about 360 nm or 365 nm is close to that of the Tiθ2, thus maximizing the intensity of the wavelength. The method and apparatus of the invention and its embodiments are based on generating the light of about 340 nm to 385 nm, preferably 360 nm or 365 nm wavelength on the photo catalytic, preferably on TiO2 surface or near to it outside of the lamp. In the present invention, the light of 340 nm to 385 nm wavelength can be produced outside of the mercury-argon light tube instead of producing the fluorescence inside it as is conventionally done in so-called black light or ultraviolet light lamp. As disclosed above, the invention and its embodiments provide an apparatus and a method for purifying a material flow, particularly air, gas or liquid. The apparatus can comprise a first source of radiation e.g. in form of a lamp or other type of radiation source. In one embodiment of the invention the first UV radiation can contain at least one of wavelengths of approximately 187 nm and 254 nm. One or more of these or other wavelengths can be generated by the first source of radiation. It is also possible to bring one ore more wavelengths from outside of the apparatus.

There can also be provided one or more housings that can surround the lamp and confine and/or direct a flow path between the lamp and the housing for the fluid to be purified by said first radiation.

The apparatus can further comprise a second source of radiation in form of a layer, as described above, containing one or more fluorescent components. In one embodiment of the invention the layer can be arranged apart from the lamp. The fluorescent component can be reactive to said first UV radiation emitted by the first source of radiation, e.g. by the lamp, to generate a second UV radiation containing at least one wavelength in the range of about 300 to 385 nm. Furthermore, it can comprise a catalytic material reactive to the second UV radiation to produce photo catalytic oxidation, preferably hydroxyl radicals, to the flow path. In one embodiment of the invention, the second source of radiation and the catalytic material are formed on a common substrate. Alternatively, said second source of radiation is formed on the inner surface of the housing.

As described above, the second source of radiation and the catalytic material can be formed as a porous filter structure located between the first source of radiation and the housing to divide the flow path into one or more departments, so that the material to be purified is adapted to flow from one department to another at least partly through said porous filter structure. When the second source of radiation and the catalytic material are formed on a common substrate, it can be folded several times along the longitudinal axis of the lamp forming the first source of radiation. The second source of radiation and the catalytic material formed on a common substrate can also have a star- like cross sectional profile in the longitudinal axis of the lamp forming the first source of radiation. The axis of the flow path can be substantially tangential to the longitudinal axis of the lamp forming the first source of radiation.

In the method of the invention a first UV radiation can be generated containing at least one of wavelengths of approximately 187 nm and 254 nm, Furthermore, a layer containing fluorescent component can be provided and arranged apart from a source of the first UV radiation. A second UV radiation can be generated containing at least one wavelength in the range of about 300 to 385 nm in response to said first UV radiation reacting with said layer, and a catalytic material reactive to the second UV radiation can be provided to produce photo catalytic oxidation, preferably hydroxyl radicals.

The arrangement of figure 3 can be set up in many different configurations depending on e.g. how strong the fluorescent light has to be, how the airflow is to be directed and how much volatile organic compounds (VOC) cleaning is required. The airflow can be generated in many ways, e.g. by one or more fans, one or more fans on the one or more lamps and/or by natural convection.

It is noted that all the figures 1 -3 describe the different lights. Figure 1 describes the light of 365 nm, Figure 2 describes the light of 254 nm and 187 nm, a conventional germicidal light, and Figure 3 describes the lamp where Tiθ2 is situated outside of the lamp but possibly close to it and with fluorescent material that generates the light substantially 340 nm to 385 nm without reducing the effect of other wavelengths of interest.

Figures 4 to 7 show more examples of arrangements of the invention and its embodiments. Figure 4 shows Tiθ2 and fluorescence material 4-37, 4-38 coating the lamp 4-50 as folded layers 4-37, 4-38. The folding can increase the surface area, the substrate area of the layer many times, e.g. along the length of the axis of the lamp thus making the cleaning effect even more efficient. In Figure 4 the airflow 4-35, 4-36 is substantially along the axis of the lamp 4-50 and/or the lamp arrangement although it can be directed also in many other different ways. To the photons having the wavelength of about 254 nm are referred by 4-39. The tube itself is disclosed by 4-50.

Figure 5 shows an arrangement with a substantially porous filter of Tiθ2 and fluorescence material that can be wrapped around the lamp 5-40. In this embodiment air can be forced at least once through the porous filter e.g. by one or more fans or by one or more air guides and by one more blocking and/or directing walls. This arrangement has the advantage of reliable and fast gas-to- surface contact and an effective VOC cleaning. The better the VOC cleaning is, the bigger the pressure drop is.

The purifier apparatus which has the lamp arrangement 3-40, 4-40, 5-40 can further comprise various means 4-30, 4-32, 4-34, 5-30, 5-32, 5-34 for guiding the flow of fluid to be decontaminated such that at least part of the flow of the fluid comes into contact with hydroxyl radicals and/or means 4-30, 4-32, 4-34, 5-30, 5-32, 5-34 for guiding the flow of fluid to be decontaminated such that at least part of the flow of the fluid is guided at least once through the radiation of the first wavelength and/or through the radiation of the second wavelength and/or through the radiation of the further wavelength. The means for the purifying device for directing the air flow at least once through the layer 3-25, 4-37, 4-38, 5-37, 5-38 can comprise e.g. one or more fans and/or one or more air guides and/or one more blocking walls and/or one or more directing walls. One or more layers can be connected 4-33 at least to the other end of the lamp 3-50, 4-50, 5-50 and/or one or more layers 3-25, 4-37, 4-38, 5-37, 5-38 can at least partly surrounds the lamp 3-50, 4-50, 5-50. The air purifiers can comprise one or more base members to which the layer 3-25, 4-37, 4-38, 5-37, 5-38 can be placed using different techniques. The layer or part of it can be painted, and/or printed, and/or etched, and/or soldered, and/or filmed, and/or evaporated and/or sputtered. The base member can be e.g. paper, plastic, wood, and concrete or other solid or semi solid material. Figure 6 shows a side view of the arrangements shown in Figures 3 and 5. The material 6-38 with TΪO2 and fluorescence compound can be wrapped around the lamp 6-40 in a star-shape configuration. The airflow is disclosed by 6-35. This is for increasing the surface size and potential contact points between VOC material and the purifying OH^" material. Many other configurations with or without foldings are possibly depending e.g. on the use of the system. These configurations include diagonal, square, circle, ellipse and hyperbole configurations and their different combinations.

In Figure 7 the air direction 7-35 between and/or through one or more layers 7-38 is tangential in relations to the axis of the lamp 7-40. This can cause turbulence to the gas and hence contact points between VOC material and OH^" material.

As already described above, there are lots of possible basic and more complex layout possibilities for the arrangements shown in Figures 3 to 7, and which can all be more or less equal in purifying capabilities and in terms of cost effectiveness. Common for these arrangements is that there is an arrangement (3-40, 4-40, 5-40) comprising a first source of radiation, e.g. a lamp (3-50, 4-50, 5-50) generating a radiation of a first wavelength (3-20). The arrangement (3-40, 4-40, 5-40) can further comprise a layer (3-25, 4-37, 4-38, 5-37, 5-38) comprising a first material, which is adapted to react to the radiation of the first wavelength (3-20) for producing hydroxyl radicals. The invention is based on the idea of providing one or more different wavelengths outside of a lamp, one of which is a wavelength, with the assistance of which OH^" rad icals can be produced, without loosing the other wavelength(s) and/or its/their efficiency. This can be achieved by only one light source.

An advantage of the method and arrangement of the invention is that very efficient purifying system can be obtained by using only one light source, which system provides hydroxyl radicals and a radiation of at least two different wavelengths. As a further embodiment of the invention, it is also possible to improve even more the efficiency of purifying mechanisms by using one or more negative ion generators and causing O2 and N₂ to become into negative ions O₂ ^" and N2^". It is thus possible to include one or more negative ion generators for the arrangements of the Figures 3 to 7. The intention of the incorporation of one or more negative ion generators with an electronics ballast of the lamp is to make the arrangement even more economical, because now only one circuit board is needed for the device. Letting the air pass over a very high negative potential can generate negative ions. The potential can range even from about -5000V to -10.000V. Negative electric potential has a higher charge density of electrons, which are negatively charged. Electric potential can be said to be basically the amount of or lack of electrons. As the negative potential becomes strong enough, it will not be energetically efficient for the electrons to stay at one place and hence they will start to move into the surrounding air e.g. as a corona discharge or as a spark to conducting material that equalizes the charge. Normally this is the ground. When e.g. air passes or is passed over this extremely high density of electrons, the electrons can attach to the gas molecules causing them to become negatively charged negative ions. These ions are relatively short-lived, which means that they should be generated before the lamp and not after it. Alternatively they can be generated before and after causing the purifier to emit negative ions into the room air. The ion generators can be placed e.g. before the air purifiers.

As yet another embodiment of the invention, the intensity of the peak that generates ozone from oxygen molecules, can be controlled. This can be done for the reason that if the light itself is strong, the generation of O₃ can be too high. The controlling can be done in many ways. One example is constructing the light tube with two different types of glasses, one of which passes the 187 nm light and the other one which blocks the 187 nm light. Alternatively, the amount of ozone that the purifier generates, can be controlled by coating the outside of the light tube partially with a compound that passes the 254 nm light or by restricting the airflow close to the light. A third way is to prevent or inhibit the flow of air close to the light source and thus not generating much ozone out from the purifier.

The light from a mercury lamp is predominantly at discrete wavelengths. Other practical UV sources with more continuous emission spectra include xenon arc lamps (commonly used as sunlight simulators), deuterium arc lamps, mercury-xenon arc lamps, metal-halide arc lamps, and tungsten-halogen incandescent lamps. It must be noted that the main mercury emission wavelength is in the UVC range. Unshielded exposure of the skin or eyes to mercury arc lamps that do not have a conversion phosphor can be dangerous. Although only decontamination is described above, also other types of purifying and cleaning can be achieved according to the invention and its embodiments. These are e.g. disinfection, detoxification, deodorising, deletion of offensive odour, or bad smell, purification of gas (e.g. air) or liquid (e.g. water), processing of exhausting gas, processing of waste liquid, generation of hydrogen and/or oxygen from water or humidity, speeding up of a chemical reaction and dissolving of pollutants or contaminants causing e.g. social pollution.

The invention and its embodiments can be used for air cleaners, for gas cleaners, for fluid cleaners and/or for liquid cleaners in hospitals, in ships, in swimming halls, in space applications, in window manufacturing applications, in clean rooms etc. Other applications comprise the use in ice cube machines.

The present invention and its embodiments provide e.g. an apparatus, a method, a lamp, a lamp arrangement and an air purifier for purifying a material flow.

The advantage of the invention is that instead of the two different light sources, only one light source can be used for obtaining the desired purifying system with one or more required wavelengths and/or hydroxyl radicals.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. An apparatus (3-40, 4-40, 5-40) for purifying a material flow (4-35, 4-36, 5-35, 5-36), particularly air, gas or liquid, comprising a first source of radiation (3-50, 4-50, 5-50) in form of a lamp (3-50,

4-50, 5-50) generating a first UV radiation containing at least one of wavelengths of approximately 187 nm and 254 nm; a housing surrounding the lamp (3-50, 4-50, 5-50) and confining a flow path between the lamp (3-50, 4-50, 5-50) and the housing for the flow to be purified by said first radiation; characterized in that the apparatus (3-40, 4-40, 5-40) further comprising a second source of radiation in form of a layer (3-25, 4-37, 4-38) containing fluorescent component and arranged apart from the lamp (3-50, 4-50, 5-50), said fluorescent component being reactive to said first UV radiation emitted by the lamp (3-50, 4-50, 5-50) to generate a second UV radiation containing at least one wavelength in the range of about 300 to 385 nm; and a catalytic material reactive to the second UV radiation to produce photo catalytic oxidation, preferably hydroxyl radicals, to the flow path.

2. An apparatus (3-40, 4-40, 5-40) as claimed in claim 1, characterized in that the second source of radiation and the catalytic material are formed on a common substrate.

3. An apparatus (3-40, 4-40, 5-40) as claimed in claim 1 or 2, characterized in that said second source of radiation is formed on the inner surface of the housing.

4. An apparatus (3-40, 4-40, 5-40) as claimed in claim 1 or 2, characterized in that the second source of radiation and the catalytic material are formed as a porous filter (5-37, 5-38) structure located between the first source of radiation and the housing to divide the flow path into department, so that the material to be purified is adapted to flow from one department to another through said porous filter (5-37, 5-38) structure.

5. An apparatus (3-40, 4-40, 5-40) as claimed in claim in any one of claims 1 to 4, characterized in that the second source of radiation and the catalytic material are formed on a common substrate, which is folded (4-37, 4-38) several times along the longitudinal axis of the lamp (3-50, 4-50, 5-50) forming the first source of radiation.

6. An apparatus (3-40, 4-40, 5-40) as claimed in any one of the preceding claims, characterized in that the axis of the flow path is substantially parallel with the longitudinal axis of the lamp (3-50, 4-50, 5-50) forming the first source of radiation.

7. An apparatus (3-40, 4-40, 5-40) as claimed in claim in any one of claims 1 to 4, characterized in that the second source of radiation and the catalytic material are formed on a common substrate having a star-like (6- 37, 7-37) cross sectional profile in the longitudinal axis of the lamp (3-50, 4-50, 5-50) forming the first source of radiation.

8. An apparatus (3-40, 4-40, 5-40) as claimed in claim 7, characterized in that the axis of the flow path is substantially tangential to the longitudinal axis of the lamp (3-50, 4-50, 5-50) forming the first source of radiation.

9. An apparatus (3-40, 4-40, 5-40) as claimed in any one of the preceding claims, characterized in that the catalytic material and the fluorescent component are constructed layerwise and/or the fluorescent material is distributed within the catalytic material.

10. An apparatus (3-40, 4-40, 5-40) as claimed in any one of the preceding claims, characterized in that the second UV radiation contains particularly the wavelength of about 365 nm.

11. An apparatus (3-40, 4-40, 5-40) as claimed in any one of the preceding claims, characterized in that the catalytic material comprises one or more of: photo catalytic material, TΪO2, aluminium, copper, or any other material that can act as a catalyst and generate hydroxyl radicals.

12. An apparatus (3-40, 4-40, 5-40) as claimed in any one of the preceding claims, characterized in that the first source of radiation is a mercury-argon light tube.

13. An apparatus (3-40, 4-40, 5-40) as claimed in any one of the preceding claims, characterized in that the layer containing fluorescent component is painted and/or printed and/or etched and/or soldered and/or filmed and/or evaporated and/or sputtered.

14. An apparatus (3-40, 4-40, 5-40) as claimed in any one of the preceding claims, characterized in that it further comprises a negative ion generator.

15. A method for purifying a material flow (4-35, 4-36, 5-35, 5-36), the method comprising generating a first UV radiation containing at least one of wavelengths of approximately 187 nm and 254 nm, c h a r a c t e r i z e d by providing a layer (3-25, 4-37, 4-38) containing fluorescent component and arranged apart from a source of the first UV radiation; generating a second UV radiation containing at least one wavelength in the range of about 300 to 385 nm in response to said first UV radiation reacting with said layer; and providing a catalytic material reactive to the second UV radiation to produce photo catalytic oxidation, preferably hydroxyl radicals.