Multi stage disinfecting air cleaner

Abstract

A portable air filtration apparatus capable of rapid and efficient room air turnover and recirculation of filtered and decontaminated air with eradication of both microorganisms and biological agents. The invention relates to a compact device that can be used in ultra-clean air purification using a multi stage electrostatic precipitation and air filtration with disinfection and eradication of both microorganisms and biological agents by the application of ultraviolet light radiation. It can be used in any application where space, lower cost or ultra-fine particulate filtering is needed; such as in clean rooms and surgical suites. The device is extremely efficient for purifying contaminated air from entrained dust and organic substances without using chemicals and physical filters, and it is hygienic and fireproof. The device including its multi stage electrostatic precipitator with the filter, connecting, releasing tubes and the fan is easy to clean and can be portable.

Claims

1. An air purification system comprising: a high voltage corona discharge chamber having a discharge electrode and collector electrode fluidly coupled to an air inlet port the high voltage corona discharge chamber being powered by a first high voltage power supply; a high voltage linear electric field chamber fluidly coupled to the corona discharge chamber, the linear electric field chamber containing an outer first electrode, and a concentric porous barrier filter second electrode; the high voltage linear electric field chamber having a hollow interior constructed to allow air to flow from the linear electric field chamber through the porous barrier filter second electrode and into the hollow interior, the high voltage linear electric field chamber being powered by a second high voltage power supply; an ultra-violet (UV) light chamber fluidly coupled to the hollow interior of the porous barrier filter second electrode, the UV light chamber including at least one UV light source; an activated charcoal filter constructed to pass air from the UV light chamber to an exit port through an exhaust fan; wherein, the fan draws ambient air through the corona discharge chamber, through the high voltage linear electric field chamber, through the porous barrier filter second electrode, through the UV light chamber, through the charcoal filter and into the exit port.

2. The air purification system of claim 1 wherein the corona discharge chamber and the linear electric field chambers are cylindrical.

3. The air purification system of claim 1 wherein the system will pass at least 400 cfm of air from the inlet port to the exhaust port.

4. The air purification system of claim 1 further comprising a wheeled housing.

5. The air purification system of claim 1 wherein the UV chamber includes a UV reflective material.

6. The air purification system of claim 1 wherein the UV light chamber includes a plurality of UV sources.

7. The air purification system of claim 1 wherein the at least one UV light source is a mercury vapor discharge light source.

8. The air purification system of claim 1 wherein the at least on UV light source is an LED.

9. The air purification system of claim 1 wherein the system is powered by AC line voltage.

10. The air purification system of claim 1 wherein the system is powered by batteries.

11. An air purification system comprising a fan configured to draw ambient room air through a high voltage corona discharge region powered by a first power source and subsequently through a high voltage linear electric field filter that has a first solid electrode and a second porous electrode, wherein the room air is passed through the second porous electrode; the high voltage linear electric field filter being powered by a second power source; the fan also configured to draw the room air from the linear electric field filter through an ultra-violet (UV) light region and an activated charcoal filter.

12. The air purification system of claim 11 wherein the corona discharge region is a cylindrical corona discharge chamber.

13. The air purification system of claim 11 wherein the linear electric field filter is a cylindrical chamber that includes the first solid electrode and concentrically the second porous electrode.

14. The air purification system of claim 13 wherein the second porous electrode has hollow interior region, and wherein the room air passes through the porous second electrode into the hollow interior region.

15. A method of purifying air from a room comprising: drawing the air from a room through a corona discharge region; drawing the air through a linear electric field region, the linear electric field region having at least one porous electrode; passing the air through the porous electrode; drawing the air through an ultra-violet (UV) light beam; expelling the air back into the room; wherein the linear electric field region comprises outer and inner concentric conductive cylinders, the outer conductive cylinder being solid, and the inner conductive cylinder being porous, wherein the outer and inner conductive cylinders form electrodes configured to produce a linear electric field.

16. The method of claim 15 wherein the corona discharge region is contained in a high voltage corona discharge chamber.

17. The method of claim 15 wherein said room air is passed through a charcoal filter prior to being expelled back into the room.

18. An air purification system comprising: (a) an electrostatic barrier filter (EBF) comprising: (i) a high voltage corona discharge chamber having a discharge electrode and collector electrode fluidly coupled to an air inlet port; (ii) a high voltage linear electric field chamber fluidly coupled to the corona discharge chamber, the linear electric field chamber containing a conductive porous barrier filter element having a hollow interior constructed to allow air to flow from the linear electric field chamber through the conductive porous barrier filter element and into the hollow interior; (b) a germicidal section comprising: an ultra-violet (UV) light chamber fluidly coupled to the hollow interior of the porous filter element, the UV light chamber including at least one UV light source; (c) an activated carbon section comprising: an activated charcoal filter constructed to pass air from the UV light chamber to an exit port through an exhaust fan; wherein, the fan is configured to draw ambient air from a room through the electrostatic barrier filter, through the germicidal section, and, through the activated carbon section, returning purified air to the room.

Description

DESCRIPTION OF THE FIGURES

(1) Attention is now directed to several figures that illustrate features of the present invention.

(2) FIG. 1 shows a stage-by-stage representation of an embodiment of the present invention.

(3) FIG. 2 is a schematic diagram of the embodiment of FIG. 1.

(4) FIG. 3 shows a corona discharge mechanism.

(5) FIG. 4 shows an arrangement of electrodes in an electrostatic precipitator.

(6) FIG. 5 shows details of an electrostatic cleaning cell.

(7) FIG. 6 shows details of a barrier filter.

(8) Several illustrations have been provided to aid in understanding the present invention. The scope of the present invention is not limited to what is shown in the figures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) FIG. 1 shows a side-by-side layout of an embodiment of the present invention. The invention relates to a filter device for removing and/or destroying organic substances in contaminated air. Embodiments comprise a housing and at least one ventilator or fan for sending an air stream through the housing. There are, in open connection with each other, a first zone with an opening which is connected to a source of contaminated air; a second zone 1 where the airflow can be immediately exposed to a high-tension corona discharge electric field which results in a strong ionic flow thus charging and collecting the incoming effluent. Subsequently, the charged flow enters a third zone 2 containing a high-tension uniform electric field that causes the charged particles to migrate to one of the oppositely charged electrodes. One of the electrodes can be made of porous filter material such as sinter metal, sinter stainless steel or other porous conducting material that allows the cleaned gas to flow into a fourth zone while filtering the remaining effluent that is collected prior to the ultra-clean gas being directed into a forth zone 3 with a number of lamps for radiating the air current with ultra-violet light. This zone has a volume allowing it to contain the air current for a predetermined interval of time, and includes an opening through which the purified air may be released to the ambient. An optional activated charcoal filter 4 and follow the fourth zone, or the air can be directly returned by the ambient after the fourth zone. A fan or ventilator 5 moves the air through the system.

(10) After entering through the inlet opening (first zone) the air moves into the second zone of the housing. The air first passes through one or more ionizing wires or charging points 1. The wires are energized at a relatively high voltage of several thousand volts. There the ionizing wires impart an electrical charge on the molecules air flow (second zone), creating charged molecules known as ions, some of which eventually cling to airborne particles. Additionally, a corona created on the ionizing wires generates ozone which is capable of chemically reacting with organic molecules so as to break down organic contaminants, this in addition to the germicidal action of the subsequent UVC lamp can kill pathogens. The air flow next encounters the third stage of the electrostatic precipitator 2 or series of concentric particle collection tubes 8, 9, which are energized in a bi-polar fashion, separately from the ionizing wires thus creating a uniform high-tension electrostatic field. The charged concentric collection tubes attract the charged particles from the air stream, and due to the static charge thereon from the power source, deposits the particles removed from the air stream onto the concentric precipitator tubes.

(11) One of the electrodes 9 can be made of porous filter material that allows the cleaned gas to flow into the fourth zone while filtering the remaining effluent that is collected prior to the ultra-clean air being directed into a fourth zone 4 with a number of lamps for radiating the airflow with ultra-violet light with a volume allowing the airflow, at predetermined interval of time, to stay in the zone, and which has an opening through which the purified air is released to the ambient or put through an optional activated charcoal filter.

(12) The ionizing and precipitator plates are energized by power sources 6, 7 contained in a separate portion of the Disinfecting Air Cleaner housing. Typically, the power sources may be located in a base portion directly under or next to the electrostatic filter portion. In other embodiments the power source may be located in a location where space and electrical wire routing best permits. An inverter converts a relatively low voltage to the high voltage required to drive the ionizing wires and electrostatic precipitator pipes. The lower voltage supply may be a 115-volt alternating current supply, or other voltage supply as available. Other embodiments can be powered by self-contained batteries, either rechargeable or disposable varieties. The power consumption of the ionic wires and the precipitator is quite low making the powering of the invention from batteries feasible. Depending on the type of germicidal lamp used, the largest consumer of electrical energy in the device can be the germicidal UVC lamp. For example, for illustration, using a commonly available germicidal mercury arc UVC GTL3 series miniature lamp having an ANSI standard E17 base lamp powered at 10 volts, the lamp consumes 3 watts, or about 300 mA at 10 volts. In the case of battery powered embodiments, for lower power consumption, the UVC lamp can be switched off if desired, although its use is highly desirable. The power consumption of the UVC germicidal lamp is a motivator for the use of an externally powered arrangement.

(13) As discussed previously, one of the concentric electrodes can be made of porous filter material that allows the cleaned gas to flow into the next zone while filtering the remaining effluent that is collected prior to the ultra-clean gas being directed into a zone with a number of UV-C lamps for radiating the air current with ultra-violet light. This zone has a volume allowing it to contain the air current for a predetermined interval of time, and includes an opening through which the purified air is released to the ambient.

(14) In other words, prior to exiting the Disinfecting Air Cleaner, the air encounters the germicidal section having an ultraviolet (UV) lamp which emits short wavelength UV light in the germicidal spectrum (UVC). For highest germicidal efficiency the UVC light source should emit at around 222 to 270 nm wavelength. The air duct region surrounding the UVC light source is provided with a UVC reflective material to multiply by reflection the germicidal effect of the UV lamp emissions. As stated, particular embodiments of the subject air purifier are battery operated, and in such battery-operated embodiments, the UVC lamp is necessarily of limited wattage so as to conserve battery life and limit the space requirements for the UVC lamp. In such battery powered embodiments, the use of reflective materials in the germicidal portion of the Disinfecting Air Cleaner are especially beneficial. It is seen as preferable that the Disinfecting Air Cleaner be powered from an external power supply since the battery operation has its limits on the use of higher wattage and therefore higher UVC intensity germicidal lamps.

(15) Air flow leaving the germicidal portion then enters the ozone filter portion of the housing. The apparatus can be equipped with an activated charcoal filter to help remove odors that may have made it past the ionic purifier as well as to remove ozone. Ozone is produced by all ionic air purifiers as a byproduct to the air ionization process. Ozone in significant concentrations is an irritant to the human body, and it is desirable to reduce its presence in the outlet air stream of the purifier. A limitation of conventional ionic purifiers is that they do not provide a means of removing ozone from the outlet air stream. In the air purifier of the present invention, the purifier is provided with a replaceable activated charcoal filter located after the electrostatic and germicidal purifier portion of the housing. Activated charcoal has been tested and shown to be very effective in removing ozone from an air stream directed through the filter.

(16) An article as published in the American Industrial Hygiene Association Journal of September, October 1999, summarizes the results of a study at the University of Minnesota on the removal of ozone using activated carbon filters. The findings include the following quotation “Activated carbon filters can be very effective at ozone removal, although not indefinitely because chemical reactions of ozone and carbon change the carbon.” Therefore the addition of a user replaceable activated carbon filter following the ionic purifier can be advantageous in two ways, first by absorbing additional odors and chemicals from the air stream that may have made it past the ionic purifier, and secondly by removing ozone created in the ionic purifier from the air stream and thereby preventing the addition of another chemical irritant to the air.

(17) The Multi Stage Disinfecting Air Cleaner according to the present invention is designed to operate quietly as it has no moving parts except of the fan, and relies upon the forced air flow through the “tail” air vents to provide the motive force to drive the air through the device.

(18) By means of this construction, the procedure according to the invention can be carried through efficiently and economically. The respective zones are following each other with the fifth zone being the last. The air current, which is generated by the fan, is then successively passing the various zones and thereby run through the processes which finally result in purified and decontaminated air being released into the environment.

(19) The fan can in principle be inserted any place at all in the air current, but it is most expedient to place the fan after the exit zone and connect its opening with the suction side of the ventilator.

(20) The air passing through the fan is thereby purified and decontaminated air only, which prevents the build-up of a coating of organic substances from contaminated air in the fan, which would reduce the efficiency of the fan.

(21) From the source of contamination, the contaminated air streams into the first zone via its inlet. Since it may be more than a single gas passage required to accommodate the overall gas flow, it is important that the air is distributed equally in the parallel channels for the processes to run at their optimum. For this purpose, according to the invention, there can advantageously be placed one or more distribution plates in the first zone, preferably somewhere behind the inlet opening of the air.

(22) Filtered and purified air flows then into the outlet portion of the housing where it flows through diffusers and out into the surrounding ambient of the Disinfecting Air Cleaner.

(23) FIG. 3 shows details of a corona discharge section. An ionizing electrode 14 creates a corona 10 that forms ions 12 that are attracted to a ground electrode 11. The ionizing electrode is usually negative; however, a reversed system will also work with the center electrode positive. Either configuration is within the scope of the present invention.

(24) FIG. 4 shows a corona discharge section in tandem with a set of linear field electrodes 12, 13. This embodiment of an electrostatic precipitator simply passes the air through a passage. There is no bag or porous filter in this embodiment.

(25) FIG. 5 shows details of an electrostatic cleaning cell with a porous filter in the center. FIG. 6 shows details of the operation of a porous pass-through filter.

(26) In a second embodiment of the Multi Stage Disinfecting Air Cleaner particularly suited to low power operation from self-contained batteries, the mercury arc UVC lamp is replaced with one or more ultraviolet UVC spectrum rated light-emitting diodes (LEDs). The LEDs consume nominally 20 mA each up to 50 mA each for the ‘superflux’ LED varieties and so greatly reduce the power drain compared to the GTL3 series or larger more effective UVC lamps.

(27) In a third series of embodiments of the present invention, the Multi Stage Disinfecting Air Cleaner is provided with means of connecting an external power source, eliminating the need for batteries internal to the air purifier housing. Embodiments of the externally powered MSDAC are well supplied with the power to utilize higher wattage UVC lamps such as available UVC rated mercury arc lamps to provide potent germicidal irradiation of the ducted ambient air.

(28) Thus, the air purification system of the invention is portable and extremely easy to use. All that an operator need do is to wheel it into a room and plug it into an electrical receptacle. The resident can benefit from clean, purified air immediately. Further, embodiments of the invention can be equipped with a set of directional vanes designed to set up the correct air patterns.

(29) The clean, purified air is most effectively directed upwards, across the ceiling, and drops down around the total room area via the walls, pushing any dust, pollen or odors toward the floor and back into the unit. While the unit of the invention is effective wherever it is placed within the room, its placement is recommended at a wall opposite the region in which the clean air benefits are most desired.

(30) Industry guidelines suggest four (4) to six (6) air changes (turnovers) per hour (ACH) for adequate airborne cleaning and allergy control. Particular embodiments of the system of the present invention will change up to 393 cfm (667 m.sup.3/hr), or as high or higher than 400 cfm.

(31) The upward air discharge provided by the system of the invention more completely mixes the air in a room by using the ceiling and upper spaces of the room to completely distribute the air to all areas. When air flow patterns move across the ceiling and upper spaces, there is no obstruction for the air getting back to the Disinfecting Air Cleaner unit. When there is no obstruction, the mixing of all the air is more complete, and therefore, the filter unit is more effective with less drafts than prior art side, bottom or front air discharge type units seen on the market today. This top discharge allows higher air flow rates to better clean the air rapidly with complete mixing, resulting in cleaner and purer air to breathe throughout the room.

(32) As can be appreciated, the size or capacity of the fan assembly depends on the size of the housing and the size of the room in which air purification is desired, and the extent of purification needed. The American Society of Heating, Refrigeration and Air Conditioning Engineers or ASHRAE has published recommendations for ventilation in Tuberculosis (AFB) isolation rooms. Clearly, the most current experience with the COVID-19 pandemic had taught that the requirement dictated by the COVID-19 requirements should be at least as stringent as ones described herein. These recommendations specify that such rooms should have at least four (4) to six (6) total air changes per hour, including at least two (2) outside air changes per hour, with sufficient within-room air distribution to dilute or remove tuberculosis bacilli from locations where healthcare facility personnel or visitors are likely to be exposed. ASHRAE recommends that emergency rooms, waiting rooms, and the like have at least ten (10) air changes per hour. The recommended air changes for trauma rooms are twelve (12) air changes per hour, five (5) of which should be outside air. The LEGI-SLATE Report for the Federal Register, L-S ID Number 471062 (4506 lines), Page: 58 FR 52810 NO. 195, dated Oct. 12, 1993, by the Department of Health and Human Services, Centers for Disease Control and Prevention provides a draft of guidelines for preventing the transmission of tuberculosis in health care facilities. Table S3-1 of that report shows how many air changes per hour and time in minutes are required for removal efficiencies of 90%, 99% or 99.9% of airborne contaminants. That report states that with 6 air changes/hour, it takes 69 minutes to reach a 99.97% removal efficiency; at 10 air changes/hour, it takes 41 minutes to reach a 99.97% removal efficiency; and at 20 air changes/hour, it takes 21 minutes to reach a 99.97% removal efficiency.

(33) The updated Table B.1. below, revised by the CDC, substitutes the Table S3-1 of the report.

(34) TABLE-US-00002 TABLE B.1 Air changes/hour (ACH) and time required for airborne-contaminant removal by efficiency* Mins. Req for Removal Mins. Req for Removal ACH 99% Efficiency 99.8% efficiency 2 138 207 4 69 104 6 46 69 8 35 52 10 28 41 12 23 35 15 18 28 20 14 21 50 6 8 *This table is revised from Table S3-1 in reference 4, and has been adapted from the formula for the rate of purging airborne contaminants.

(35) The particular embodiments of the present invention are designed to achieve up to 20 air changes per hour for a typical room installation.

(36) As can bee appreciated, power consumption, unit noise and room size, and hence volume of air to be filtered, are all design factors to be considered in choosing a particular fan for a particular size unit. For example, to provide 10 room air changes per hour in a room having a 15 by 20 floor area and an 8 foot ceiling (2,400 cubic feet volume), it would require moving 400 cubic feet per minute (cfm) of air for one (1) hour, or sixty (60) minutes.

(37) Several descriptions, illustrations and examples have been given to aid in understanding the present invention. One with skill in the art will realize that numerous changes and variations may be made without departing from the spirit of the invention. Each of these changes and variations is within the scope of the present invention.