Field of the invention

The present invention relates to a system for air cleaning in a completely or partially closed room, the system having at least a first system of channels connected to at least an air inlet from the closed room for suction of a first airflow of polluted air to a first chamber, and a outlet from the first chamber, the outlet via a channel system being in connection with the closed room for introduction of another air flow of completely or partly cleaned air, the system having a number of light-sources for generation of UV- light which UV-light transforms part of the oxygen molecules in the air to ozone by irradiation.

The present invention also relates to an apparatus for air cleaning, the apparatus having at least a first air inlet to a first chamber, this first chamber being connected to at least an air outlet incorporating a blower for exhaust where the apparatus comprises at least a UV-light source where UV-radiation of air results in ozone enrichment of the air.

Background of the invention

Using both UV-radiation and ozone in treatment of air for sterilizing air is commonly known. This technique is also known from water treatment, it being possible by means of combined UV-light and simultaneously flow through liquid including ozone to sterilize almost completely, and attaining decomposition of all organic compounds at the same time, hi the art of air-treatment, it is known from WO 97/34682 and WO 99/13956 and WO 99/13956 to apply light-generating sources in the form of tubes creating UV-light, air flowing around such tubes in a manner such that the air is exposed to UV-radiation to carry out sterilisation, and subsequently the air will be mixed with ozone created during UV-radiation of air. Ozone can be produced from the same tube, possibly as the tube in one end comprises a coating such that the tube is radiating light with another wavelength. From said patent applications, it is also known that controlling and regulating the content of ozone in the air to be blown into a room is desired.

WO 92/10429 relates to air cleaning by means of ozone, the ozone being produced from a UV-tube around which a medium to be sterilized is flowing, and which medium by means of deflector plates is forced to flow around a centrally placed UV-tube.

WO 03/061717 describes automatic control of the content of ozone in airflow by applying means for controlling the airflow in that computer-based measuring-equipment is monitoring and controlling the content of ozone in the discharge air.

WO 03/092752 also relates to air sterilizing by letting polluted air pass through a fil- ter, before the air is exposed to UV-radiation producing ozone in the air passing through. Measuring and control systems for controlling the content of ozone in the cleaned air are described.

A disadvantage in the art is that lamps or tubes producing UV-light are surrounded by polluted air, in this way either providing the possibility to influence a shield which is situated around the lamps or giving rise to direct settling of particles on the lamps.

Any kind of dirt will reduce the effective amount of light. At the same time, greater amounts of dirt will eventually have the consequence that the light sources are being overheated, whereby the operating life of the light sources is strongly reduced. At the same time, the general pollution of lamps means that quite often cleaning or premature replacement of lamps must be done, because the operating life of the lamps is reduced, and cleaning maybe necessary with relative short time intervals.

Objective of the invention The objective of the invention is to achieve an effective air cleaning by means of a controlled addition of ozone to polluted air, and a second objective is to avoid contact between polluted air and UV-light sources in order to obtain a stabile system.

Description of the invention A system as described in the introduction may advantageously be performed with at least a second inlet for a third air flow of fresh air, where the UV-generating light sources may be placed in another chamber which is provided with fresh air, where ozone enriched fresh air can be passed through a partly separation into the first cham-

ber where the third flow of air with ozone enriched fresh air can be mixed with the first flow of air of polluted air from the first inlet, and where the second air flow of the mixed airstreams can be passed through the channel system to the closed room.

Hereby it can be achieved that light sources are not being placed in the air flow of the polluted air, but instead in an air flow of relatively fresh air. At the same time a very effective mixture of ozone enriched fresh air with polluted air is obtainable. During the mixture, a considerable reduction of ozone content in the completely mixed air which is conducted to the outlet occurs. By this, it is relatively easy to maintain an ozone concentration at a level beneath a certain limit. A system such as the one mentioned above may advantageously cooperate with a fresh air system such that the fresh air being supplied will be brought through the system as indicated here, but the fresh air being able to pass the plant in time periods without developing ozone. In this way, the plant will be effective and can be applied indoor, e.g. in living areas for people, where the fresh air system functions normally, while people are staying in the rooms, but during time periods without people staying in the rooms, ozone concentration in the injection air may be increased substantially, and sterilisation in the surrounding room is established.

The invention will be well suited as fresh air plant in stables, where polluted air with a content of ammonium and sulphur compounds can be cleaned by means of ozone. Ozone is a strong means of oxidation, which in the correct concentrations, is able to oxidize other reducing chemical compounds, including ammonium and different sulphur compounds. In this way, admixture of ozone can have a very useful effect on a stable environment, but in connection with renewed injection of the cleaned air it may be of necessity to control the level of ozone in the injected air to avoid damaging animals or people.

The system may advantageously include at least a detector for detecting the ozone air content in at least one of the air streams or in the closed room. In this way, it is possible to control the current ozone level in the air streams e.g., inside channels before air is blown into a closed room. If the concentration is crossing a limit value, the system

is able to close down automatically, such that the ozone concentration automatically will decrease.

The system can include at least one blower for moving air. Hereby, a forced flow- through of air in the system can be achieved. A number of blowers may be necessary in connection with a bigger system of channels, both in the supply direction to the system and in the channels leading from the system. In the same way, other blowers may be necessary in connection with the fresh air inlet, if a long channel is necessary to provide access to fresh air.

The system can include means for automatic control of the ozone level in the closed room, where the system can be cooperating with at least one detector, where the ozone level is controlled in such a way that a first limit value is not exceeded in the control of the UV-producing light sources. Hereby, an automatic control of the ozone content can be achieved in that the amount of produced ozone and injection speeds into the closed room will be varied as a function of the measured value in this way securing that the ozone content in the closed room always lies beneath a first limit value which is completely without risks for animals and people, while a further limit value for instance could be a safety value never to be exceeded. The system maybe so constructed that exceeding the safety value means an immediately closing down of the system. Automatic control of the UV-producing light-sources may be provided by on/off- switching of a number of different light sources. In this way, it will be possible to regulate in increasing or decreasing direction by alternating switching on and off the individual light sources. The light sources may be so constructed that they have a minimal, optimal burning time, i.e. a minimal time for reasonable operation. This means, that the illumination from the light sources may be controlled via an effective pulse-width-modulation, the minimum pulse-width being the minimum time for the lamp to be switched on.

Advantageously, the system can cooperate with a cooling system which can cool down the injected air, the cooling effect being regulated as a function of at least a temperature measurement in the closed room. In this way it can be realized that together with sterilisation of the air before this air is blown back to e.g. a stable, the air can be

cooled down, such that by means of the cooling system an effective temperature control of the climate in the stable is established. By cooling down the inlet air, it is possible completely or partly to cut off existing exhaust systems, because a cooling system together with ozone cleaning of the air may result in such an effective cleaning of the air in a stable and further ventilation not is necessary.

A further advantage can be achieved, if the injection system will be regulated in such a way that the air pressure in the closed room or in the stable is higher than the pressure in the surroundings. In this way, it can be realised that ammonia gas primary is passed along the floor and out through existing slurry channels. Because ammonia is heavier than the surrounding air, this is an optimal solution for reduction of the concentration of ammonia in a stable.

Optimal temperature control can be achieved, if the cooling system is formed as a real air-condition system, whereby a cooling system also can be used as a heat pump, and when the ambient temperature is critically low, it will be possible to realise a heating of a closed room or a stable in such way that the heat pump most probably produces heat in a competitive manner to other sources of energy.

A combination of climate control and cleaning of air will most likely result in a lower mortality among pigs in piggeries. It is also to be expected that better living conditions for pigs will result in an increased body growth of the pigs. Said system results in significant economical improvements for the farmer who possibly chooses to establish a system of this type.

An apparatus such as described in the introduction may advantageously be designed in such a way that the apparatus includes at least a second chamber, where this second chamber may include the UV-generating light source(s), whereby this second chamber can be in communication with a fresh air inlet having a partly open connection with an air stream from the second chamber to the first chamber.

Hereby, an effective apparatus can be achieved which may be suspended in a closed room, where a reduction of bacteria or virus is desired. It is necessary for the operation

of the apparatus to have a fresh air inlet, but apart from this an apparatus may be constructed for application in hospitals, in domestic houses, in physical training centres or in other places where a relatively sterilized atmosphere is wanted. Of course it will also be possible to apply the device in stables where it could be part of a larger system, as mentioned above. Several apparatuses are able cooperate in larger stable systems, naturally.

The first and the second chamber may advantageously be separated by a perforated plate through which ozone enriched fresh air is flowing. Hereby, it may be realized that the perforated plate is providing an effective separation between the first and the second chamber such that the polluted air only in very limited degree is going to move against the flow of fresh air being sucked through the perforated plate such that the ozone generating tubes by means of the perforated plate will effectively be protected against pollution coming from the air. Other embodiments than perforated plates could be mentioned, all technical means, which in some way or another creates a pressure drop and ensuring a separation between the two airstreams and blocking the flow of polluted air into the second chamber, could be applied as an alternative to the perforated plate. A perforated plate is applied, as it at present time is a relatively cheap and effective way of separating the two chambers.

The apparatus can include a number of UV-generating light sources being switched on and off as a function of the actual level of ozone in relation to at least a limit value. In this way, control of the separate light sources can be realized in a simple manner and so establish an effective control of the ozone level in that room which is in comrnuni- cation with the apparatus. So it will also be possible to make a measurement of the degree of air pollution, and based on this determine how much ozone should be produced and thereby how many light sources should be switched on. hi this way, the apparatus is able to operate with a feed-forward control instead of the most probable - using a signal indicating the real ozone content for determining how many of the light sources must be active.

The apparatus can include an electronic, automatic control system, the UV-generating light-sources being in connection with an electronic automatic control system, also in

connection with at least one ozone detector, the electronic, automatic control system on the base of measured ozone values regulates the speed of at least one blower, whereby the electronic, automatic control system regulates the setting of at least one inlet damper. In this way, it can be achieved that the electronic, automatic control sys- tern totally controls the different functions of the apparatus. Advantageously, the electronic, automatic control system can include one or more microprocessors being programmed to implement the different functions. So, on the base of different measuring values, it will be necessary to establish a picture of the real ozone content and the current need for adding ozone to a closed room, after which, based on the actual need, also may comprise measurement of temperature. Hereafter, the system is able to control and regulate the ozone producing light-sources and one or more blowers respectively, which are being applied to secure an air passage through the apparatus and at the same time control the possible dampers being arranged for achieving a limitation of the amount of air being sucked into the apparatus, hi this way a completely auto- matic working apparatus can be realized. The apparatus may be extended to include time-based controlling deciding that the ozone content in a closed room on different times has a different value. This can for instance be applied, if the apparatus is being used in connection with an operating room, where a relatively high ozone level is wanted during the time span where the operating room not is in use, while during op- erating periods, lower ozone content is wanted in order not to hurt staff or patients.

Description of the drawing

Fig. 1 illustrates an elementary sketch of a system according to the invention, where

fig. 2 illustrates a sectional view through an apparatus, where

fig. 3 illustrates a sectional view through the same apparatus as in fig. 2.

Detailed description of the invention Fig. 1 illustrates an elementary sketch of a system (2), comprising an ozone generating apparatus (4), this ozone generating apparatus (4) being equipped with an inlet (6) for access of polluted air to a first chamber (7), from which chamber (7) is arranged an outlet (8) for passing cleaned air back to the closed room. The apparatus also incorpo-

rates an inlet (10) for fresh air being passed into another chamber (11) being limited partly from inlet (10), but also towards the first chamber (7) by perforated plates (12), where, between the perforated plates (12), ozone generating lamps of the UV-tube (14) are arranged. A damper (16) is regulating the amount of fresh air, whereas the damper (18) regulates the amount of polluted air. A blower (20) is connected with the chamber (7) and provides the necessary transport of air into and out of the apparatus (4). In the outlet connection (8) an ozone detector (22) is placed.

The operating principle of the invention as illustrated in fig. 1 is that polluted air from a closed room, which could be an operating room in a hospital or perhaps a stable or another closed room, where it is wanted to sterilize the inflowing air to the chamber (7), where an admixture with fresh air takes place, which fresh air coming from the channel system (10) through the damper (16) and through the perforated plates (12) into the UV-tubes (14) irradiating the fresh air with ultraviolet light, whereby ozone is created. Ozone-enriched air will thereafter flow from the chamber (11), through the perforated plate (12) into the first chamber (7), where the ozone-enriched air is admixed with the polluted air, which is blown through the tube systems (6). Here ozone will react with bacteria and other living organisms incorporated in the polluted air, after which cleaned air will be sucked into the outlet pipe stub (8) through the blower (20) and back to the closed room. For reasons of health, it is necessary to control the ozone concentration in the closed room, which is why an ozone detector (22) is applied. In praxis, a large number of ozone detectors will be placed partly in the tube systems, but also in the closed room in different distances from possible inlet nozzles. So it will be possible to control the ozone-concentration in the closed room in a very effective way. This concentration can be varied depending on whether animals or people are present in the closed room. If animals or people will have to stay in the room, the concentration will be lower, while in periods where cleaning of for instance an operating room or a stable is wanted, it will be reasonable to significantly increase the ozone-concentration.

Fig. 2 illustrates a section through an apparatus (104) having air injecting stubs (106) for injecting polluted air into a first chamber (107). From the chamber (107) an outlet connection (108) back to the closed room is provided. In the bottom of the apparatus

(104) an inlet stub (110) for fresh air is shown. This fresh air stub (110) is in communication with second chamber (111), which is delimited by perforated plates (112) in relation to the first chamber (107). The second chamber (112) comprises a number of UV-tubes (114). The inlet stub (110) incorporates a control damper (116). The inlet stubs (106) incorporate control dampers (118). Connected with the outlet stub (108), a ventilator in the form of a blower (120) is shown. In the bottom of the apparatus (104) is shown an electronic, automatic control system (124) which by means of cables (126) is connected to the UV-tubes (114).

Fig. 3 is a sectional view through the illustration in fig. 2, and the same numbering is used for the different technical details, hi fig. 3 the electronic control units (124) are depicted more clearly, and at the same time doors (130) in the front of the apparatus (104) are shown. These doors can cooperate with a system of contacts, the function of the contacts is, that the UV-light from the tubes immediately will be switched off, when the doors are being opened. So it is avoided that persons operating the apparatus (104) will be exposed to radiation.

An apparatus as illustrated in fig. 2 can be applied in connection with any fresh air system in that the apparatus is able to work as fresh air system without the UV-tubes being active, in this way securing a common injection of air, e.g. during periods of time, where ozone in the air is not wanted, but during periods without a closed room being used, the UV-tubes may be switched on, and it is possible to increase the UV- concentration. In closed rooms e.g. like a operating room, a high ozone concentration in time periods, where the room is not in use, will provide a nearly total sterilisation of the entire room. In a stable, a small ozone concentration will result in significantly better living conditions for animals living in the stable. For people occasionally bound to stay in the stables, the indoor climate will be significantly more pleasant. So there will not be an inconvenient smell of ammonia in the stables, and the amount of bacteria traditionally staying in a stable will be heavily reduced. The better living conditions in the stables, will, in relation to pigs, result in significant lower medicine consumption, but at the same time a faster growth and therewith an increased earning for the farmer applying a system such as the one described.