WO2011091583A1

WO2011091583A1 - Method and apparatus for air cleaning

Info

Publication number: WO2011091583A1
Application number: PCT/CN2010/070373
Authority: WO
Inventors: Chi Keung Rudy Chan; Yee Lam Chan; Lam Lung Yeung; Ka Tung Ho
Original assignee: RHT Ltd
Current assignee: RHT Ltd
Priority date: 2010-01-27
Filing date: 2010-01-27
Publication date: 2011-08-04
Anticipated expiration: 2012-07-27
Also published as: JP2013517852A; CN103282058A; JP5633759B2; CN103282058B

Abstract

An air cleaning apparatus and a method for removing air contaminants are disclosed. The air cleaning apparatus comprises a housing (1) in which at least one adsorbent filter (2) and at least one reactive oxidizing species (ROS) generator (3) are installed. The adsorbent filter (2) is positioned at the surface of the housing (1) and exposed to the air for adsorption of air contaminants. The ROS generator (3) for generation of ROS is enclosed by both the housing (1) and the adsorbent filter (2). The method comprises the following steps: a) the air cleaning apparatus is placed in the polluted environment; b) the adsorbent filter (2) adsorbs air contaminants from the environment; c) after/during the adsorption of air contaminants by the adsorbent filter (2), ROS are released from the ROS generator (3) for decomposition of air contaminants and rejuvenation of the adsorbent filter (2). The apparatus can operate without power supply and creation of disturbance like airflow and noise during adsorption process.

Description

METHOD AND APPARATUS FOR AIR CLEANING

FIELD OF THE INVENTION

The present invention relates to air cleaning, more particularly, to a method and an apparatus for air cleaning.

BACKGROUND OF THE INVENTION

Nowadays, the problem of indoor air quality is getting more concern for people since it is recognized as the cause of human health hazard. Air contaminants, such as total volatile organic compounds (TVOC), ammonia, hydrogen sulfide, bacteria and virus, can threaten human health. It is essential to have a solution for these problems.

U.S. Pat. No. 7,473,074 and 5,042,457 illustrate that dilution of air contaminants using fresh air is an effective way to maintain good indoor air quality. However, assess to fresh air may not be possible due to site situation constraints, especially in cases where air duct and air delivery unit is difficult to be installed. Furthermore, this approach cannot lead to the elimination of air contaminant while transferring the air contaminants to other areas that may eventually induce more serious air problems.

U.S. Pat. No. 6,152,996, 5,350,444 and 7,316,736 illustrate that air purifier is an alternative solution for improvement of indoor air quality. Most air purifiers consist of an air delivery unit and a filter. The working principle at behind is that air contaminants are adsorbed by the filter when air is diverted into air purifier by the air delivery unit. The drawbacks of this type of air purifier are:

Air contaminants will be adsorbed in the filter which may cause a secondary pollution;

The size of this type of air purifier is large due to the presence of the air delivery unit;

Noise disturbance can be caused by the air delivery unit;

Power supply is required for the air delivery unit.

Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.

SUMMARY OF THE INVENTION

The present invention relates to a method and an air cleaning apparatus for removing air contaminants but without causing disturbance towards environment and secondary pollution so that it can be widely used in various situations.

One aspect of the present invention is providing an air cleaning apparatus for the removal of air contaminants, such as total volatile organic compounds (TVOC), ammonia, hydrogen sulfide, bacteria and virus in domestic, commercial or industrial areas.

The present invention of the air cleaning apparatus comprises a housing in which at least one adsorbent filter and at least one reactive oxidizing generator are installed. The adsorbent filter is positioned at the surface of the housing and exposed to the air. The ROS generator is enclosed by both the housing and the adsorbent filter.

The adsorbent filter used to adsorb air contaminants by diffusion comprises of adsorption materials and a porous enclosure. The ROS generator is used to generate reactive oxidizing species, which diffuse towards the adsorption materials for decomposition of air contaminants, thus the adsorbent filter is rejuvenated for further adsorption. As ROS generator enclosed by the housing and the adsorbent filter, the adsorption materials decompose excessive ROS thereby avoiding the leakage of ROS.

The present invention provides a rejuvenation system, in which the air contaminants and ROS are confined in the pores of adsorption materials. Unlike the gaseous phase reaction, the air contaminants and ROS are held closely with each other in the range of nanometer scale, thereby enhancing the efficiency of the ROS in decomposing air contaminants into non-harmful product, such as water and carbon dioxide, thereby avoiding a secondary pollution. Since the oxidized products are too small to be retained inside the pores, they will diffuse out from the pores for further adsorption of air contaminants.

The present invention comprises two processes: adsorption of air contaminants and rejuvenation of adsorbent filter. These two processes can take place at different or same time. Hence there are two kinds of combination in operation:

1) Adsorbing the air contaminants until the adsorbent filter being saturated, then releasing ROS for rejuvenation of the adsorbent filter;

2) Adsorbing the air contaminants by the adsorbent filter and releasing ROS for rejuvenation of adsorbent filter at the same time.

Regarding the first combinations operation, adsorption of air contaminants and rejuvenation of adsorbent filter can take place at different locations. The time for adsorption of air contaminants and rejuvenation of adsorbent filter is not limited and can be adjusted separately depending on application.

Regarding the second combination operation, adsorption of air contaminants and rejuvenation of adsorbent filter should take place at same time and of course at same place.

Unlike the traditional air purifier, the air cleaning apparatus of the present invention operates without electricity during adsorption process, thereby being applicable at different locations in flexible time. Furthermore, no air delivery unit is installed in the air cleaning apparatus thereby preventing from operational constraints such as supply of electricity and generation of disturbance towards the environment, such as airflow and noise. For speeding up the adsorption process by the adsorbent filter, the air cleaning apparatus of the present invention can be placed somewhere with airflow such as outlets of fan and air conditioner.

Another aspect of the present invention is to provide an air cleaning method for removing air contaminants by employing the air cleaning apparatus according to the present invention, said method comprising following steps:

1) The air cleaning apparatus is placed in the polluted environment;

2) The adsorbent filter of the air cleaning apparatus adsorbs air contaminants from the environment;

3) After/During the adsorption of air contaminants by the adsorbent filter, ROS are released from the ROS generator for decomposition of air contaminants and rejuvenation of the adsorbent filter;

Moreover, the adsorbent filter is re-used again for further adsorption.

These and other aspects of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the following drawings, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate one or more embodiments of the invention and, together with the written description, serve to explain the principles of the invention. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment, and wherein:

FIG.1 is a schematic diagram of the air cleaning apparatus according to one embodiment of the present invention;

FIG.2 is a schematic diagram of the adsorbent filter according to one embodiment of the present invention;

FIG.3 is an air cleaning method by employing the air cleaning apparatus according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

These and other advantage, aspect and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understand from the following description and drawings. While various embodiments of the present invention has been presented by way of example only, and not limitation.

In one embodiment (referring FIG.1), the air cleaning apparatus of the present invention comprises a housing 1, in which an adsorbent filter 2 and a ROS generator 3 are installed. The adsorbent filter 2 is situated at the surface of the housing 1 and exposed to air so that the adsorbent filter 2 has large surface area to adsorb air contaminants from surrounding by diffusion. The ROS generator 3 enclosed by both the housing 1 and the adsorbent filter 2 generates ROS. There is no boundary between the adsorbent filter 2 and the ROS generator 3 so that ROS can diffuse into the adsorbent filter 2 for decomposition of adsorbed air contaminants and rejuvenation of the adsorbent filter 2.

The shape of the housing 1 can be rectangular, cubic, square, cylindrical or other regular or irregular shapes. The materials of the housing can be metal, wood, plastic, ceramic or other suitable materials. The housing 1 is sealed to avoid leakage of ROS.

FIG. 2 shows the structure of the adsorbent filter 2 according to one embodiment of the present invention. The adsorbent filter 2 comprises a porous enclosure 4 and adsorption materials 5. The shape of the adsorbent filter 2 can be rectangular, cubic, square, cylindrical or other regular or irregular shapes. The adsorption materials 5 are impregnated into the porous enclosure 4, which comprises of at least one covering layer 6 and a framework 7. The pore size of the covering layer 6 is smaller than the diameter of the adsorbent materials 5 for preventing the loss of adsorption materials 5, while it is large enough to allow either air contaminants or ROS to diffuse into the adsorption materials 5. The covering layers 6 can be plastic net, metal net, cloth, HEPA (High efficiency particulate air Filter) and/or foam. The framework 7 forms the shape of the adsorbent filter 2 and provides mechanical support to the adsorbent filter 2. The materials of the framework 7 can be metal, paper, wood, plastic or other suitable materials.

The adsorption materials 5 can be activated carbon, zeolite, metal oxide framework, alumina, silica or in mixture of the aforementioned materials. The shape of the adsorption materials 5 can be spherical, cylindrical, or other rectangular, irregular, or in the form of pellets and granules with length or diameter in the range of 1 to 10 mm. Also, the adsorption materials 5 can be sponge coated with adsorption granules or powders. The pore size of the adsorption materials 5 is tuned in the range of 4 to 20 Angstrom for effective adsorption of air contaminants. The property of the adsorption materials 5 can either be hydrophobic or hydrophilic or in physical mixture of both for enhancing the adsorption capacity of both polar and non-polar air contaminants. Catalysts (such as transition metals) can be incorporated into the porous structure of the adsorption materials 5 so as to enhance the decomposition rate of air contaminants. The choice and amount of the adsorption materials 5 are determined by the nature and amount of air contaminants, one skilled in the art may choose appropriate species and amount of adsorption materials 5 based on the polluted environment.

In other embodiment (referring FIG. 1), the ROS generator 3 is positioned near the adsorbent filter 2 so that ROS generated by the ROS generator 3 can diffuse into the adsorbent filter 2 for decomposition of air contaminants. The ROS generator 3 can be ion generator, charged particle generator, ozone generator, peroxide generator, radical generator (such as hydroxyl radical generator), reactive oxidizing gas generator, and/or electrostatic precipitator. The ROS can be cation, anion, charged particles, ozone, peroxide, radicals (such as hydroxyl radical), or any other reactive oxidizing gases. The ROS can be generated by electrical method such as electrostatic precipitator and corona discharge, chemical method and photolytic method (such as UV). Excessive ROS are easily confined and decomposed by the adsorption materials 5 for avoiding leakage. The choice and amount of ROS are determined by the nature and amount of air contaminants, one skilled in the art may choose appropriate species and amount of ROS based on the polluted environment.

In the present invention, no air delivery unit is installed so the apparatus can operate without power supply and creation of disturbance like airflow and noise during adsorption process. The rejuvenation process makes the adsorbent filter become semi permanent without causing secondary pollution. As the adsorption and rejuvenation process can be taken place separately, the present invention is more versatile to be applied in different location at flexible time even in case of no power supply.

The present invention also provides a rejuvenation system, in which the adsorption materials 5 are rejuvenated by ROS for further adsorption. Unlike the gaseous phase reaction, the air contaminants and ROS are confined in the pores of the adsorption materials 5 and held closely with each other in the range of nanometer scale, thereby enhancing the efficiency of ROS in decomposing air contaminants into non-harmful product such as water and carbon dioxide thereby avoiding the secondary pollution. Since the oxidized products are too small to be retained inside the pores, they will diffuse out from the pores for further adsorption of air contaminants thus rejuvenating the adsorption materials 5.

The present invention comprises two processes: adsorption of air contaminants and rejuvenation of adsorbent filter 2. These two processes can take place at different or same time. Hence there are two kinds of combination in operation:

1) Adsorbing the air contaminants until the adsorbent filter 2 being saturated, then releasing ROS for rejuvenation of the adsorbent filter 2;

2) Adsorbing the air contaminants by the adsorbent filter 2 and releasing ROS for rejuvenation of adsorbent filter 2 at the same time.

Both of the two combinations in operation can be applied for different application. Regarding the first combination operation, adsorption of air contaminants and rejuvenation of adsorbent filter 2 can take place at different locations. Hence electricity is not needed at the working environment during adsorption process. The period for adsorption of air contaminants and rejuvenation of adsorbent filter 2 is not limited and can be adjusted separately depending on actual application.

Regarding the second combination operation, adsorption of air contaminants and rejuvenation of adsorbent filter should take place at same time and of course at same place. That has higher air contaminant removal rate because the adsorbent filter 2 gets refreshed continuously but electricity is needed at the working environment for the ROS generator 3.

According to present invention, the rejuvenation process makes the adsorbent filter become semi permanent without causing secondary pollution. As the adsorption and rejuvenation process can be taken place separately, the present invention is more versatile to be applied in different location at flexible time even in case of no power supply. For speeding up the adsorption process by the adsorbent filter, the air cleaning apparatus of the present invention can be placed somewhere with airflow such as outlets of fan and air conditioner.

FIG.3 is an air cleaning method by employing the air cleaning apparatus according to one embodiment of the present invention. The method of present invention comprises following steps.

In step 1, the air cleaning apparatus is placed in the polluted environment;

In step 2, the adsorbent filter of the air cleaning apparatus adsorbs air contaminants from the environment;

In step 3, after/during the adsorption of air contaminants by the adsorbent filter, ROS are released from the ROS generator for decomposition of air contaminants and rejuvenation of the adsorbent filter;

In step 4, the adsorbent filter is re-used again for further adsorption.

In other embodiment of present invention, other air cleaning apparatus discussed above also can be used to perform the operation flow chart disclosed in FIG. 3. Moreover, the adsorbent filter according to present invention can be used again and again for further adsorption without any additional cleaning.

The foregoing description is just the preferred embodiment of the invention. It is not intended to limit the invention. Any modifications, variations, and amelioration without departing from the spirit and scope of the present invention should be included in the scope of the prevent invention.

Claims

1. An air cleaning apparatus, which comprising of a housing in which at least one adsorbent filter and at least one reactive oxidizing generator are installed, wherein, the adsorbent filter is positioned at the surface of the housing and exposed to the air for adsorption of air contaminants, wherein the ROS generator for generation of ROS is enclosed by both the housing and the adsorbent filter.

2. The air cleaning apparatus according to claim 1, wherein a plurality of adsorbent filters are positioned at the surface of housing, and a plurality of ROS generators are enclosed by both the housing and the plurality of adsorbent filters.

3. The air cleaning apparatus according to claim 1, wherein the shape of the adsorbent filter is rectangular, spherical, cylindrical, square or cubic.

4. The air cleaning apparatus according to claim 3, wherein the adsorbent filter comprises a porous enclosure with adsorption materials impregnated in.

5. The air cleaning apparatus according to claim 4, wherein the porous enclosure comprises a framework for forming the shape of the adsorbent filter and at least one covering layer covering the framework.

6. The air cleaning apparatus according to claim 5, wherein the pore size of the covering layer is smaller than the diameter of the adsorbent materials for preventing the loss of adsorption materials, meanwhile the pore size of the covering layer is large enough to allow either air contaminants or ROS to diffuse into the adsorption materials.

7. The air cleaning apparatus according to claim 5, wherein the materials of the framework are metal, paper, wood or plastic, wherein the covering layer are plastic net, metal net, cloth, HEPA or foam.

8. The air cleaning apparatus according to claim 4, wherein the adsorption materials are activated carbon, zeolite, metal oxide framework, alumina, silica or in mixture of the aforementioned adsorption materials.

9. The air cleaning apparatus according to claim 8, wherein the shape of adsorption materials is spherical, cylindrical, rectangular, irregular or in the form of granule and pellet with size from 1 to 10mm.

10. The air cleaning apparatus according to claim 8, wherein the pore size of the adsorption materials is in the range of 4 to 20 Angstrom.

11. The air cleaning apparatus according to claim 8, wherein the adsorption materials are hydrophobic, hydrophilic or in a mixture of both.

12. The air cleaning apparatus according to claim 8, wherein catalysts are incorporated into the porous structure of the adsorption materials to enhance the decomposition rate of air contaminants.

13. The air cleaning apparatus according to claim 4, wherein the adsorption material is sponge coated with adsorption granules or powders.

14. The air cleaning apparatus according to claim 1, wherein the ROS are cation, anion, charged particles, ozone, peroxide, radicals or reactive oxidizing gases.

15. The air cleaning apparatus according to claim 14, wherein, the ROS generator includes at least one of the listed generators: ion generator, charged particle generator, ozone generator, peroxide generator, radical generator, reactive oxidizing gas generator and electrostatic precipitator.

16. The air cleaning apparatus according to claim 15, wherein the ROS are generated by electrical, chemical or photolytic method.

17. The air cleaning apparatus according to claim 10, wherein air contaminants are confined and decomposed inside the pores of the adsorption materials.

18. The air cleaning apparatus according to claim 17, wherein the ROS diffuse into adsorption materials and decompose the confined air contaminants into non-harmful products and rejuvenate the pores of the adsorption materials.

19. The air cleaning apparatus according to claim 14, wherein excessive ROS are decomposed by the adsorption materials for avoiding leakage.

20. An air cleaning method by employing the air cleaning apparatus according to any one of claim 1-19, wherein, said method comprising the steps:

a) the air cleaning apparatus is placed in the polluted environment;

b) the adsorbent filter of the air cleaning apparatus adsorbs air contaminants from the environment;

c) after/during the adsorption of air contaminants by the adsorbent filter, ROS are released from the ROS generator for decomposition of air contaminants and rejuvenation of the adsorbent filter.