WO2008034444A1

WO2008034444A1 - Method and system for air cleaning

Info

Publication number: WO2008034444A1
Application number: PCT/DK2007/000411
Authority: WO
Inventors: Lars Leth Pedersen
Original assignee: LLP HOLDING, ASÅ ApS
Priority date: 2006-09-20
Filing date: 2007-09-20
Publication date: 2008-03-27
Also published as: EP2069044A1; DK201000202U3

Abstract

The present invention relates to a system (2) and method for cleaning of air, which system comprises at least one tube (4), which tube comprises at least one air inlet (6), and at least one air outlet (8), which tube (4), forms a mostly open flow channel from the inlet (6), to the outlet (8), which tube (4), comprises means for generating an airflow in the tube (12), which tube comprises means for generating droplets (16), of a liquid, which liquid droplets interact with particles contained in the air flowing through the tube (4), which tube comprises means for separating liquid droplets (18), from the flowing air. The tube (4), comprises, further, blowing means (20) placed in cnj unction with the tube inlet (6), which blowing means (20), generates a full or partly circulating airflow through the tube (4), the outlet (8), comprises means for flow restriction (22).

Description

Method and system for air cleaning

Field of the Invention

The present invention relates to a system and a method for cleaning of air, which system comprises at least one tube, which tube comprises at least one air inlet and at least one air outlet, which tube forms a mostly open flow channel from the inlet to the outlet, which tube comprises means for generating an airflow in the tube, which tube comprises means for generating droplets of a liquid, which liquid droplets interact with particles contained in the air flowing through the tube, which tube comprises means for separating liquid droplets from the flowing air.

Background of the Invention

WO 2005/061078 Al describes an apparatus for cleaning of air including an air ex- haust, a ventilator, a moisturising chamber with a number of nozzles, an air intake and a liquid collecting unit, where a central part is entirely or partly designed as a double- walled pipe section having, that is with an internal and external pipe, and that the apparatus furthermore includes an air diffuser which is disposed downstream of the ventilator at one end of the internal pipe.

In the above-mentioned patent application there is a relatively high demand for water during operation. The nozzles probably use several litres per hour to moisture the incoming air. Some of the water drops of course evaporate, however, many of the drops combine and form much bigger drops, which fall down inside the apparatus as a kind of waste water.

Object of the Invention

It is the object of the invention to describe a highly efficient system for cleaning of air, by means of which system the power demand is low and the consumption of liquids limited. A further object of the invention is to achieve a mostly unrestricted airflow through the system. It is also the object of the invention to clean air without using filters.

Description of the Invention The object of the invention can be achieved, if the tube comprises blowing means placed in conjunction with the tube inlet, which blowing means generates a full or partly circulating airflow through the tube, which tube at least in the direction towards the outlet comprises means for flow restriction.

This way the tube is mostly open for limited flow restriction, and the circulating air moves relatively slow through the tube to let the droplets generated inside the tube stay in the tube for a relatively long period leading to a high degree of contact between the droplets and the particles possibly contained in the contaminated air, this is higly effective if the size of the droplets compares to the size of the particles the contami- nated air.

According to a preferred embodiment of the invention the liquid can be based on water, where the water contains at least one chemical additive, which chemical additive reduces the surface tension of the droplet water surface, which leads to the forming of small and long living droplets, and which chemical additive also is efficient for deodorizing the air. This leads to the production of smaller droplets, where these droplets live much longer simply because the low surface tension does not force the droplets against each other to recombine. This can lead to highly efficient cleaning of air. Where the additive also has a deodorizing effect, bacteria are killed. It will be possible to use essential oil, which is a concentrated, hydrophobic liquid containing volatile aromatic compounds extracted from plants.

One possible chemical additive to deodorize air could be Sinodeen, which exists in many forms. However, Sinodeen is a very efficient chemical substance, which is pro- duced out of natural chemical substances. The flow restriction in the tube can be formed by bending the tube or by forming the outlet in a branch-T connected to the tube. This achieves an efficient and well-defined flow restriction. Other kinds of flow restrictions are also possible.

It is preferred to keep the size of the contaminant particles in the air in mind, when sizing the droplets. This way water droplets are produced, which droplets approximately compare to the size of the particles, which they have to collect. This may result in very small droplets to clean air from e.g. gases forming relatively small molecules and to the use of rather big droplets, if dust is to be collected.

The droplets can be formed in at least one nozzle, where different nozzles can be selected depending on the size of particles. Thus, different nozzles can be selected depending on the size of the particles in the contaminated air.

The system can comprise means for measuring the size of the contaminant particles in the air, which system comprises a number of different nozzles generating droplets of different sizes, which system furthermore comprises means for selecting one or more nozzles to operate depending on the measured particle size. Hence the nozzles are selected automatically depending on the actual size of the particles in the contaminated air. As an alternative to selecting between nozzles it is possible to develop nozzles producing droplets of different sizes by manual or automatic adjustment.

The system can based on the measured size and number of the contaminant particles in the air adjusts the amount of liquid that is being lead towards the nozzle. Hereby, it can be achieved that the amount of liquid is reduced to the smallest possible amount needed for achieving the best possible result, hi some embodiments of the invention, a situation might occur where this invention is also used for cooling the air flowing through the tube. In this situation, the cooling demand may instead have some influence on the amount of liquid being added through the nozzle. The combined cooling and cleaning effect might in this invention be used as a form of air condition equipment. The system can also based on the measured size of the contaminant particles in the air adjust the amount of additive added to the liquid, hi this way, it can be achieved that the additive which can be rather expensive is only used when absolutely necessary. In a situation where detection means are indicating that there is a high concentration of bacteria and also a high number of gas particles an increasing level of additive can be added to the liquid.

The size of the droplet may vary between 0,25 μm and 200μm. Hence it is possible to clean the air in most gases needing particles in the size from 0,5-5 micrometers, and it is possible to catch nearly all kinds of dust particles which needs particles in the size the droplets bigger than 30 micrometers. Different kinds of gases and different kinds of dust may lead to the use of droplet sizes, which are must different from the ones mentioned, so that the entire range from 0,25-200 micrometers is used.

At least a section of the tube can be coated on the inside by means of a photo catalyst, which photo catalyst generates charged ions when radiated by UV light, and which tube comprises means for generating UV light. This achieves another method for sterilizing the air flowing through the tube. The combined treatment of air results in that the air leaving the tube is extremely clean meaning that the tube may be used in e.g. hospitals.

The photo catalyst can be based on Titaniumdioxid (TiCh ). The use of Titaniumdi- oxid in combination with the water droplets leads to the formation of OH^" and O₂ ^". These active ions lead to oxidation of airborne pollution, and they reduce the chemical pollution into carbon dioxide and water. This way the combined treatment of Sinodeen leads to very efficient reduction of the pollution in air, and all kinds of odours are removed automatically. Thus the invention may be used in e.g. stables; however, it can also apply for private homes and hospitals.

In a preferred embodiment for the invention the tube can be mounted vertical- upwards, where the inlet is placed upwards, where blowing means generates a downwards circulating air stream, where the restriction element is placed at the bottom of the tube, which restriction element is formed of a cup, which cup contains a liquid. Hereby can be achieved that the cup placed at the bottom of the tube in operation works as the flow restriction means and a further effect is achieved by the circulating air through the tube in that the liquid contained in the cup will evaporate and in the central part of the circulating air, the air pressure would be reduced so much that evaporated liquid will be drawn upwards also in a circular movement. If this liquid is a kind of soap which is used for the air cleaning this soap can in this way be added instead of being added to the water that is sprayed through the nozzle. Because the cup is placed at the bottom of the tube, this can be replaceable and it will be easy just to remove the cup, clean it up and fill it up with a new liquid. By placing the inlet upwards it can be achieved that the product could be placed near a sealing or at least in the top of a wall in a room where the air probably is most polluted. The hot polluted air will then be cleaned by passing through the tube and also to a certain degree be cooled down. This cool air will after leaving the tube fall downwards. In this way the air in a room will automatically be replaced just by one air cleaning device placed somewhere at a wall at best placed as high as possible at the wall. The cooling effects of an air cleaning device depend on the amounts of water that is evaporated in the device. If a temperature reduction is the primary reason for operating a device, the amount of water particles sprayed through the nozzle can be adjusted to a higher level than the amount of water which is necessary just for cleaning of air.

This invention may also be used for cleaning exhaust gases, e.g. from cars. Cars operating without catalysts can use a system for cleaning exhaust gas as described above. The tube can be connected to the tail pipe under the car in this way reducing tail pipe emissions from the car.

This invention could probably also be reduced in conjunction with diesel engines where the exhaust gas is cleaned for carbon particles.

This invention can also be used in conjunction with all air condition systems in which the outlets of numeral cooling and humidifying systems are sent through a tube, thereby achieving a sterilization of the air that is led into a building as described in this invention. Also in conjunction with pressurised air, this invention can be very effective as oil contaminated pressurised air can be totally cleaned for oil particles through a system like this. At the same time, the pressured air can be sterilized which can be very important in e.g. hospitals where pressured air is used for a lot of different purposes. The air can be sterilized just after leaving the compressor, but the invention as such can also be used at the outlet of pressurised air in cases where there is a sufficient demand for sterilized air such that the cleaning and sterilization of the air is being performed just before use.

Description of the Drawing Fig. 1 shows a first possible embodiment of the invention and fig. 2 shows a second embodiment of the invention, and fig. 3 shows a third and preferred embodiment of the invention and fig. 4 shows a fourth preferred embodiment of the invention, and fig. 5 shows a fifth preferred embodiment of the invention.

Detailed Description of the Invention

Fig. 1 shows a sectional view of a first embodiment of a system 2 according to the invention. A tube 4 has an inlet 6 and an outlet 8. Near the inlet 6 blowing means 12 are shown, hi the tube means 14 to generate droplets 16 by a nozzle 26 are shown. Means 18 to separate the liquid droplets 16 from the air are shown at the downside of the tube. Near the outlet 8 a flow restriction 22 is shown.

During operation the blowing means 20, which could be formed by a propeller, generate a circulating air stream along the tube 4. This circulating air stream passes near one or more nozzles 26, which nozzles 26 generate droplets 16 of water into the circulat- ing air stream. As the air circulates the period in which droplets 16 are active in the air stream are relatively high. The droplets 16 interact with dust or other particles contained in the air. The droplets of water 16 catch all kinds of particles, and afterwards the droplets are combined into bigger droplets, which due to the circulating air stream, are collected by the inner wall of the tube. The water collected by the inner wall can be led to an outlet (not shown), and the water after a cleaning process is ready to be used again in the nozzles. In the circulating air stream a great part of the water droplets evaporates, at least enough droplets to reduce the temperature of the air passing through the tube. The flow restriction 22 results in that the period in which the droplets operate in the air stream increases, otherwise the air and the water mist is immediately blown out of the tube 4. The flow restriction 22 can be formed in many different ways, and only a few of the possible solutions are mentioned in this patent application.

Fig. 2 shows a first sectional view of an alternative embodiment of the invention. Most of the technical features are identical to the ones shown in fig. 1, thus they will not be mentioned again. The only difference is that the flow restriction 22 is formed as a bending 24 of the tube towards the outlet.

During operation there is a very weak, but absolutely necessary flow restriction of the bending 24.

Fig. 3 shows a sectional view of a third embodiment of the invention. Most of the te- chnical features of fig. 1 and fig. 2 are common and thus not described in detail. The difference is that the tube 4 in fig. 3 comprises a coating 30. This coating 30 may be a photo catalyst containing Titaniumdioxide (TiO₂). In the middle of the tube is shown an ultra violet generating tube 32, which generates the ultra violet light in a wave length of approximately 280 nanometres.

During operation the invention according to the embodiment shown in fig. 3 operates in such way that the water droplets 16 collect dust or other particles contained in the air. The water droplets 16 are half as big as the particles to be collected. This means that water droplets can be sized in the range of 0.25 - 5 micrometers to function against odours and in the range from 10 micrometers and upwards to function against dust. In some applications nozzles are used to form droplets in different sizes. It is preferred that the water contains a chemical additive to reduce the droplet water surface tension. One possible chemical substance is a chemical by the name of Sinodeen. The UV-light generated by the tube 32 activates the photo catalyst 30, which forms OH^" and O₂ ^", which are very active oxidation ions. This leads to a very aggressive oxidation, which is able to kill all kinds of bacteria contained in the air passing between the tube 32 and the coating 30 allowing this system to be used in hospital operation rooms. The system can sterilise an operation room during operation, or it could be used to clean the air, when the operation room is empty.

Figure 4 shows a system 102 comprising a tube 104. The tube 104 has an inlet 106 and an outlet 108. Air blowing means 112 are placed in the middle of the tube 104, and just behind these blowing means 112, means 114 to generate droplets 116 by a nozzle 126 are shown. At the bottom of the tube 104 are indicated means 118 for collecting liquid. The blowing means 112 comprise a rotating propeller 120. At the outlet 108 is indicated a flow restriction 122. Inside the tube, a photo catalyst 130 is indicated, and in the middle of the tube an UV-tube 132 is indicated. At the inlet 106, blowing means 140 are indicated which contain propeller means 142. Inside the tube 104 is seen a body 144 which takes up part of the internal volume between the blowing means 120 and the blowing means 140. Outside the tube 104 is seen a chamber 146 containing a liquid. The liquids are collected inside the tube near the means 118 which are sepa- rates the liquid droplets from the air where the liquid is sent to a tube 150 through pumping means 152 into a tube 154 which is connected to a chamber 146. Also from the chamber 146, a tube 156 is connected to the nozzles 126 which nozzles 126 are generating droplets 116.

In operation, contaminated air, e.g. from deep frying, can be led into the inlet 106 at a very high temperature where the blowing means 140 and the propeller 142 press the hot air around the body 144, which is formed of a heat conducting material such as aluminium, where the liquid in the chamber 146 rapidly reduces the temperature of the air. Blowing means 122 and the propeller 120 send the contaminated air further into contact with the water droplets 116 where all particles from the deep frying process are bound by the water droplets. As the contaminated air continues, it reaches the region where the UV-tube 132 produces UV-light which activates the photo catalyst 130, which further sterilizes the air. At the same time, the cleaned air is cooled down to a normal temperature and leaves the tube 104 through the opening 108.

Figure 5 shows an upwards directed embodiment of the invention. A system 202 comprises a tube 204, which tube 204 has an inlet 206 and an outlet 208. At the inlet 206, the tube 204 comprises blowing means 212. In the tube 204 is shown a nozzle fixture 21 for a nozzle 226 which generates droplets 216. The tube 204 has an inner wall 218. In the bottom of the tube 204 is shown restrictions means 222 in form of a cup. This cup 222 contains a liquid 223. Inside the tube 204 is also shown a tube 232 for generating ultra violet light. Inside the tube is further shown a coating 230. This coating could comprise titanium oxide. The tube 204 is connected to a wall 240 by a fixture 242 mounted at the wall. Also a shield 244 that covers this tube 204 is indicated.

In operation, polluted air will be drawn into the tube 204 at the opening 206 which is pointing upwards. This air will start a downwards circulating movement through the tube 204. Water droplets 216 are sprayed into the downwards circulating air. Afterwards, this air starts circulating around the UV-radiating tube 232. And the circulating air will then come in close contact with the coating 230 which is generating active oxygen ions. Because the air is circulating around the cup 222 at the outlet 208, a low pressure is achieved at the surface of the liquid 223. This very low pressure can lead to forming an upwards circulating stream of evaporated liquid. This upwards circulation continues up to the top of the tube 204 where evaporated liquid is mixed more or less with the droplets generated in the top. The cup 222 can easily be removed and be filled with a new liquid. This liquid could be a kind of soap product which otherwise should be added to the water generated as droplets in the nozzle. Hereby is achieved that the nozzle as such is only spraying clear water.

The system according to the five figures can comprise nozzles 26,126,226 producing droplets of different diameters. The system can also contain a measuring system measuring the size of the particles or the molecule size of the odour contained in the air. Based on the measurement nozzles can be selected to generate water droplets in a size matching the actual concentration of particles or odour molecules contained in the air passing through the tube.

Claims

1. System (2,102,202) for cleaning of air, which system (2,102,202) comprises at least one tube (4,104,204), which tube (4,104,204) comprises at least one air inlet (6,106,206) and at least one air outlet (8,108,208), which tube (4,104,204) forms a mostly open flow channel from the inlet (6,106,206) to the outlet (8,108,208), which tube (4,104,204) comprises means (12,112,212) for generating an airflow in the tube (4,104,204), which tube (4,104,204) comprises means for generating droplets (16,116,216) of a liquid, which liquid droplets (16,116,216) interact with particles contained in the air flowing through the tube (4,104,204), which tube (4,104,204) comprises means (18,118,218) for separating liquid droplets from the flowing air, characterized in that the tube (4,104,204) comprises blowing means (20,120,220) placed in conjunction with the tube inlet (6,106,206), which blowing means (20,120,220) generates a full or partly circulating airflow through the tube (4,104,204), which tube (4,104,204) at least in the direction towards the outlet (8,108,208) comprises means (22,122,222) for flow restriction.

2. System for cleaning of air according to claim 1, characterized in that the liquid is based on water, where the water contains at least one chemical additive, which chemi- cal additive reduces the surface tension of the droplet water surface, which leads to the forming of small and long-living droplets, and which chemical additive also is efficient for deodorizing the air.

3. System for cleaning of air according to claim 1 or 2, characterized in that the flow restriction (22) in the tube is formed by bending (24) the tube (4) or forming the outlet in a branch-T connected to the tube (4).

4. System for cleaning of air according to one of the claims 1-3, characterized in that the size of the contaminant particles in the air are kept in mind, when sizing the drop- lets.

5. System for cleaning of air according to one of the claims 1-4, characterized in that the droplets are formed in at least one nozzle (26,126,226), where different nozzles (26,126,226) are selected depending on the size of particles.

6. System for cleaning of air according to claim 5, characterized in that the system comprises means for measuring the size of the contaminant particles in the air, which system comprises a number of different nozzles (26,126,226) generating droplets (16,116,216) of different size, which system furthermore comprises means for selecting one or more nozzles (26,126,226) to operate depending on the measured particle size.

7. System for cleaning of air according to claim 6, characterized in that the system based on the measured size and number of the contaminant particles in the air adjust the amount of liquid that is being lead towards the nozzle.

8. System for cleaning of air according to claim 7, characterized in that the system based on the measured size of the contaminant particles in the air adjust the amount of additive added to the liquid.

9. System for cleaning of air according to one of the claims 1-8, characterized in that the droplet size varies between lμm to lOOμm.

10. System for cleaning of air according to one of the claims 1-9, characterized in that at least a section of the tube is coated on the inside by a photo catalyst (30,130,230), which photo catalyst (30,130,230) generates charged ions when radiated by UV light, and which tube comprises means (32,132,232) for generating UV light.

11. System for cleaning of air according to one of the claims 1-8, characterized in that the photo catalyst (30,130,132) is based on Titaniumdioxid (TiCh ).

12. System for cleaning of air according to one of the claims 1-8, characterized in that the tube is mounted vertical-upwards, where the inlet (206) is placed upwards, where blowing means (212,220) generates a downwards circulating air stream, where the restriction element (222) is placed at the bottom of the tube (204), which restriction element is formed of a cup, which cup contains a liquid (223).

13. Method for cleaning of air, which method comprises at least one tube (4,104,204), which tube (4,104,204) comprises at least one air inlet (6,106,206) and at least one air outlet (8,108,208), which tube (4,104,204) forms a mostly open flow channel from the inlet (6,106,206) to the outlet (8,108,208), which tube (4,104,204) comprises means (12,112,212) for generating an airflow in the tube (4,104,204), which method generates of droplets of a liquid, which liquid droplets (16,116,216) interact with particles contained in the air flowing through the tube (4,104,204), which tube (4,104,204) comprises means (18,1 18,218) for separating liquid droplets from the flowing air, characterized in that the method concerns blowing (20,120,220) means placed in conjunction with the tube inlet (6,106,206), for generating a full or partly circulating airflow through the tube (4,104,204), which tube (4,104,204) at least in the direction towards the outlet (8, 108,208) comprises means (22, 122,222) for flow restriction.