Air treatment system, and a method of using said air treatment system

Abstract

An air treatment system (1) arranged for treating polluted air (A.sub.pol) at least by means of an air particle filter, and wherein said air treatment system comprises an air treatment unit placed upstream of the air particle filter and being arranged for directing a sub-flow (A.sub.sub) of the polluted air (A.sub.pol) through said air treatment unit (2) and for subjecting the sub-flow (A.sub.sub) to a photooxidation process. The photooxidation process in the air treatment unit (2) is so efficient that the overall concentration of gas-pollution of the combined air flow A.sub.corn is significantly reduced whereby large volumes of polluted air can be treated in a fast, inexpensive and effective manner.

Claims

1. An air treatment system arranged for treating polluted air (A.sub.pol) at least by means of an air particle filter, said system comprises at least one duct and a fan for directing air though the air treatment system and expelling it after treatment, wherein said air treatment system comprises an air treatment unit comprising at least one UV-lamp, said air treatment unit being placed upstream of the air particle filter and being arranged for directing a sub-flow (A.sub.sub) of the polluted air (A.sub.pol) through said air treatment unit and for subjecting only said sub-flow to photooxidation, and wherein the system is arranged such that the sub-flow, after being subjected to photooxidation in the air treatment unit, is combined with the polluted air that bypass the air treatment unit and the combined air-flow is then passed over the air particle filter that is placed after the air treatment unit seen in the flow direction.

2. The air treatment system according to claim 1, wherein the air treatment unit comprises at least one catalyst, and wherein said catalyst is adapted for treating the air as a photocatalyst, or reduce the concentration of submitted ozone into the surroundings.

3. The air treatment system according to claim 1, wherein the sub-flow (A.sub.sub) directed though the air treatment unit is between 1/10 and ? of the polluted air (A.sub.pol).

4. The air treatment system according to claim 1, wherein the UV-lamp is an excimer lamp arranged for emitting a wavelength in the range between 126 nm and 240 nm.

5. The air treatment system according to claim 1, wherein the air treatment unit comprises an air treatment housing with walls, and wherein the direct distance between the walls of the unit and the surface of the UV-lamps is below 2 cm whereby the sub-flow (A.sub.sub) flowing though said unit will flow over the surface of the at least one UV-lamp and/or close to the surface of said lamp, thereby ensuring that at least 90% of the sub-flow will be exposed to irradiation.

6. The air treatment system according to claim 1, wherein the system is arranged for passing the sub-flow (A.sub.sub) through the air treatment unit with a lower flow rate than the flow rate of the polluted air (A.sub.pol) entering into the air treatment system.

7. The air treatment system according to claim 1, wherein the flow rate of the sub-flow (A.sub.sub) is about ? of the flow rate of the polluted air (A.sub.pol).

8. The air treatment system according to claim 1, wherein the air treatment system is configured to recycle the air though said system.

9. The air treatment system according to claim 1, wherein the air treatment system is a heating and/or ventilation and/or air conditioning system comprising an electrostatic precipitator and the air treatment unit is a separate unit placed in a duct of said heating and/or ventilation and/or air conditioning system upstream of the electrostatic precipitator.

10. The air treatment system according to claim 1, wherein the air particle filter is an electrostatic precipitator.

11. Use of an air treatment system according to claim 1 for treating a contaminated air steam comprising pollutants in the form of particles and organic compounds, such as VOCs.

12. A method of treating polluted air using the air treatment system according to claim 1, wherein said method comprises the consecutive steps of: passing a sub-flow of the polluted air through an air treatment unit comprising at least one UV-lamp, combining the clean sub-flow (A.sub.clean) delivered from the air treatment unit with the remainder of the polluted air (A.sub.pol) providing a combined air flow (A.sub.corn), and passing the combined air flow (A.sub.corn) over an air particle filter.

13. The method according to claim 12, wherein the sub-flow (A.sub.sub) is passed thought the air treatment unit with a lower flow rate than the flow rate of the remaining polluted air (A.sub.pol) and/or the combined air flow (A.sub.corn).

14. The method according to claim 12, wherein the polluted air is passed through the air particle filter before a sub-flow of said polluted air enters the air treatment unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in greater detail below, describing only exemplary embodiments of the exhaust gas treatment system and method with reference to the sole drawing, in which

(2) FIG. 1 schematically shown a first and preferred embodiment of an air treatment system according to the invention,

(3) FIG. 2 schematically shown a second embodiment of an air treatment system according to the invention, and

(4) FIG. 3 schematically shown a third embodiment of an air treatment system according to the invention.

(5) The invention will be described below with the assumption that the air treatment system is a HVAC system, and that the air particle filter is an electrostatic precipitator. However, this assumption is not to be construed as limiting, as the system also could be used as a stand alone system, and/or the air particle filter could be any other kind of conventional air particle filter.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(6) FIG. 1 shows a simplified embodiment of an air treatment system 1 according to the invention. The system 1 comprises an air treatment unit 2 placed upstream of an electrostatic precipitator 3 in an air duct 4 of a HVAC system; a fan 5 is arranged at the outlet for sucking/drawing polluted air A.sub.pol into the system at a first end 6a of the duct/system, and blow treated air A.sub.treat out of the other end 6b of the duct/system 1.

(7) The air treatment unit 2 comprises an UV-lamp 7 placed in close proximity to the walls 8 of the unit 2, a fan 9 for sucking a sub-flow A.sub.sub, of the polluted air A.sub.pol into a first end 10a of the unit 2 and for expelling clean sub-flow A.sub.clean at the other end 10b of said unit, and a catalyst 11 arranged for decomposing excess ozone to oxygen.

(8) The UV-lamp 7 is an elongated cylindrically tube having a longitudinal axis X arranged in the flow direction of the air treatment unit (illustrated by arrows). i.e. the air will flow along the length of the UV-lamp 7, thereby ensuring that the sub-flow A.sub.sub that enters the unit 2 has the longest possible contact time with the UV-lamp 7 and accordingly the UV-light emitted from said lamp.

(9) The speed of the two fans 5, 9 are adjusted such that the sub-flow A.sub.sub is passed thought the air treatment unit 2 with a lower flow rate than the flow rate of the polluted air A.sub.pol passing though the air treatment system 1. Such an arrangement will effectively ensure that the UV-light will get in contact with substantially all contaminates in the subflow A.sub.sub and effectively clean/treat said sub-flow, as the emitting irradiation will initiate a photooxidation process in the air, and/or ensure that ozone will be generated from oxygen present in the air.

(10) Even thought the fans 5,9 is placed at the outlet of the system 1 and the inlet of the air treatment unit 2 in FIG. 1, a person skilled in the art will understand that one or both fans also could be placed at any another suitable position.

(11) Even though the photooxidation process will basically remove organic pollutants e.g. VOCs from the sub-flow A.sub.sub, the photooxidation process is so efficient that the overall content of the organic pollutants of the combined air flow A.sub.com, i.e. in the air-flow after the air A.sub.treat that has been treated in the air treatment unit 2 is combined with the remained of the polluted air A.sub.pol, is significantly reduced.

(12) Since the major part of the polluted air A.sub.pol by-passes the air treatment unit 2, and only has to pass the electrostatic precipitator 3, which does not involve large pressure drops etc, large volumes of air can be treated using the air treatment system 1 according to the invention in a fast and effective manner.

(13) As the air treatment unit 2 in the embodiment shown is placed in a HVAC system, it is preferred that the air treatment unit 2 is an individual unit that easily can be retrofitted in the duct system 4 of the HVAC system.

(14) Existing HVAC systems will comprise means for recycling the air though said system, which is relevant if the polluted air is indoor air e.g. in a home, office or in an air plane, in which pollutants continuously is added to the air. Recycling the air thought the air treatment system according to the invention, will therefore ensure that low levels of both gas-pollutants and particles continuously will be maintained.

(15) The UV-lamp used in the present invention may be any UV-lamp capable of initiating a photooxidation process. However, in a preferred embodiment the at least one UV-lamp is an excimer lamp, which offers a number of advantages, high intensity at a defined wavelength, no-self absorption, and flexibility in the construction of the air treatment system according to the present invention. Furthermore, excimer lamps only generate little heat, making them highly suitable for air-condition and/or ventilation purposes, as cooling is not required before the treated air may be submitted into the surroundings

(16) FIG. 1 only shows the use of a single UV-lamp, however a person skilled in the art will understand that the air treatment unit may comprise two, or more UV-lamps if a larger UV-emission area is desired or if the UV-lamps are arranged for emitting different wavelengths. Accordingly, the system according to the invention can be adapted to be used in both large-area industrial applications and for domestic uses.

(17) Furthermore, a person skilled in the art will understand that even thought a catalyst is preferred in the system according to the invention, said catalyst can be omitted in the embodiment of FIG. 1.

(18) Alternative embodiments are shown in FIGS. 2 and 3, these embodiments correspond to the embodiment shown in FIG. 1, with the modification of the placement of the electrostatic precipitator 3. The embodiment shown in FIG. 2 comprises two electrostatic precipitators 3, one placed before the air treatment unit and one placed after said unit. In the embodiment of FIG. 3 the electrostatic precipitators 3 is placed before the air treatment unit, seen in the flow direction.

(19) Modifications and combinations of the above principles and designs are foreseen within the scope of the present invention.