Patent Grant
11471551
This disclosure is directed to an apparatus and method for inactivating airborne pathogens such as viruses, bacteria, and fungal spores with ozone followed by catalytic decomposition of the generated ozone.
Many diseases are transmitted from exposure to airborne pathogens such as viruses and bacteria. These organisms may be spread through sneezing, coughing, spraying of liquids, the spread of dust, or any activity that results in the generation of aerosolized particles. These aerosolized particles may be generated from a source of infection, such as body secretions from an infected patient or animal, flushing of a toilet with the lid open, or from biological waste products that accumulate in garbage, caves, and various other containers.
Once the droplets containing the pathogens have been formed, they are then dispersed via air currents and can be inhaled by susceptible hosts. The aerosolized particles may remain suspended in air for hours and can travel considerable distances. Proper precautions must be taken to mitigate the risk of infection in public places such as hospitals or private places like homes. The airborne particles may remain localized to a single room or may move to other rooms depending on the airflow.
In cases where there is inadequate ventilation, airborne particles may remain in the building or room and be inhaled by one or more occupants. To control and prevent the airborne transmission of pathogens, many methods are implemented, such as air purifiers, the practice of antiseptic techniques, wearing personalized protection equipment (PPE), and performing basic infection prevention measures like hand washing. Airborne diseases are caused by pathogenic microbes small enough to be discharged from an infected person via coughing, sneezing, laughing, and other close personal contact. The discharged microbes remain suspended in air on dust particles or water droplets.
Inhalation exposes the upper and lower respiratory tracts of humans to a variety of airborne particles and vapors. Airborne transmission of pathogenic microorganisms to humans from the environment, animals, or other humans can result in disease. Inhalation is an important route of exposure as the lung is more susceptible to infection than the gastrointestinal tract.
Ingested microorganisms must pass through the acidic environment of the stomach before they can colonize tissue while inhaled microorganisms are deposited directly on the moist surfaces of the respiratory tract. Inhalation of microbial aerosols can elicit adverse human health effects including infection, allergic reaction, inflammation, and respiratory disease. Following inhalation, infectious viruses, bacteria, and fungi can establish in host cells of the respiratory tract. Some are translocated and infect the gastrointestinal tract and other tissues.
Airborne diseases such as the common cold are typically caused by viruses such as rhinoviruses. Rhinoviruses can often change strain allowing for easier infection of humans. Another virus, varicella zoster, causes chickenpox and spreads easily among young children; The virus mumps affects the glands just below the ears, causing swelling and, in some cases, loss of hearing. The bacteria Bordetella pertussis causes the illness called whooping cough which leads to swelling of the airway. Additionally, a rapidly spreading coronavirus, SARS-CoV-2, and the disease it causes, COVID-19, continue to cause worldwide challenges. The most common symptoms of COVID-19 include fever, cough, fatigue, and shortness of breath.
To inactivate pathogens, oxidants such as ozone and hydroxyl radicals have been proposed as alternatives to traditional disinfectant compounds such as chlorinated bleach or hydrogen peroxide. Ozone is capable of being generated from air at the site of disinfection, eliminating the need to store liquid disinfectants. Ozone molecules target the DNA or RNA of viruses and bacteria, damaging the chemical structure and resulting in pathogen inactivation. In the apparatus as disclosed herein, ozone is generated within a reactor to inactivate pathogens within an airstream. The ozone is then removed along with any additional by-products formed to ensure safe release of the airstream into an environment. The apparatus operates continuously and is scalable to handle high flow rates for larger spaces as well as low flow rates for smaller spaces that may result in a smaller reactor configuration.
There exists a tremendous need for an apparatus or system to inactivate or attenuate airborne pathogens such as viruses. To inactivate or attenuate a pathogen means to cause the pathogen to lose disease producing capacity. To render a very high percentage, if not all airborne pathogens inactive, is the ultimate objective of the apparatus disclosed herein. To inactivate pathogens, ozone is generated within a reactor and mixed in an airstream. As air flows through the reactor, ozone is mixed in the airstream, contacting and inactivating airborne pathogens. Before the newly disinfected airstream can be released into the atmosphere, ozone and other by-products are removed, as ozone can cause lung irritation if inhaled. After these processes are completed, the airstream is then released back to the environment.
The apparatus, in a first embodiment as disclosed herein, is configured for placement into an enclosed space, such as a room within a private residence, a movie theater, a warehouse, a fulfillment center, a cabin of an aircraft, public transit buses, and trains. The inactivation of pathogens is critical to avoid infection of the occupants by the pathogen, where air is aspirated by human beings often in constrained spaces. In an alternative embodiment, it is also contemplated by this disclosure to develop a personal, and portable, airborne pathogen inactivation apparatus that allows a user to carry the device with them to include an appropriately configured apparatus to support breathing of the air exiting the apparatus following inactivation of the pathogens.
The apparatus, as disclosed herein, may be sized to accommodate smaller venues such as a residence or a much larger venue such as a warehouse. The apparatus may be appropriately sized to cycle through the entire volume of air contained within the structure in a set amount of time known as the clean air delivery rate (CADR). Ideally the apparatus, depending upon initial design criteria, can be manually transported to another location in the structure, such as another room of a residence should the occupant intend to spend more time in a specific room.
The disclosed device comprises a chamber or a reactor into which air is inducted with a fan through an intake opening. The intake air is pre-filtered upon entering the chamber. The objective of the pre-filter is to remove some portion of the airborne particulates; however, the preferred filter efficiency is such that it does not restrict airflow into the reactor. In other words, the preferred pre-filter would be classified as those filters known as MERV filters. MERV stands for “medium efficiency reporting value,” a rating for the capability of a filter to remove particles as large as 10 microns and smaller than 1 micron. The pre-filter would have a MERV rating in the range of 7-16, capable of removing particulates from 3 to 0.3 microns in size such as dust, oils, powders, and various larger pathogens.
The preferred embodiment of the apparatus as disclosed herein also utilizes a backflow preventer to reduce, or preferably eliminate, the potential for air leakage out of the reactor space via the intake opening, as the air may contain ozone that has not been converted to oxygen. The backflow preventer may be as basic as a hinged flapper or semi-flexible panel that stops the airflow moving through the intake area. In an alternative embodiment, an ozone decomposition catalyst located proximate the intake opening of the reactor can also provide the function of a backflow preventer such that when the intake fan to the unit is turned off, any ozone present in the air moving back out through the catalyst will be converted into oxygen before exiting through the pre-filter. The preferred embodiment utilizes manganese dioxide (MnO2) coated on a honeycomb monolithic substrate. The monolithic substrate will typically be a ceramic such as cordierite or a metal compound.
The next component within the reactor space is a fan that serves to draw air in through the intake opening of the reactor and to move it forward into the reactor space. Because the fan rotates at a high rate of speed there are frictional forces that result between the fan blades and the air that results in a build-up of static electricity. This static electricity causes dust particles to adhere to the edges of the fan blades and to reduce efficiency of the fan. The previously detailed pre-filter serves to reduce the potential for admission of dust particles that can adhere to the fan blades and other interior chamber surfaces.
A variable speed fan is also contemplated by this disclosure to address the need for increased throughput of the apparatus or reducing throughput to decrease the sound generated by the movement of air through the device when a quieter setting may be required. In various embodiments, the fan may be located (i) before the backflow preventer or first ozone decomposition catalyst, (ii) after the backflow preventer or first ozone decomposition catalyst, or (iii) proximate the exhaust opening of the apparatus disclosed herein.
Adjacent to the fan is the ozone generating device. Various embodiments of the ozone generation source are contemplated by this disclosure. A first embodiment utilizes solely a corona discharge device. In a corona discharge device, a voltage is applied between two electrodes, causing air between the electrodes to be ionized. This ionization splits diatomic oxygen, producing an atomic oxygen molecule that reacts to form ozone. Common variants of corona discharge devices include dielectric barrier discharge, non-thermal plasma, and ionic wind. It is contemplated by this disclosure that the concentration of ozone within the apparatus would be between 1 and 55 parts per million (PPM).
An undesirable by-product of the production of ozone from corona discharge in ambient air is the formation of nitrogen oxides (NOx) including nitrogen dioxide (NO2), nitrogen oxide (NO) and dinitrogen pentoxide (N2O5). These nitrogen oxides are created from corona discharge because dry air is rich in diatomic nitrogen, composed of 78% by volume. When air enters the corona discharge device, diatomic nitrogen is split in the same manner as diatomic oxygen, creating atomic nitrogen which can react with oxygen or ozone to form nitrogen oxides.
At higher concentrations of produced ozone from corona discharge, the predominant nitrogen oxide is nitrogen dioxide (NO2). This is because ozone will oxidize other nitrogen oxides like NO to NO2. The National Ambient Air Quality Standards established by the U.S. Environmental Protection Agency and codified at 40 CFR § 50.11 set a one-hour maximum nitrogen dioxide concentration of 100 parts per billion (PPB) and an average annual concentration of 53 parts per billion. The objective of the corona discharge device, as previously discussed, is to generate ozone at a sufficiently high concentration and with a residence time sufficient to inactivate airborne pathogens. The nitrogen oxides by-products are undesirable and are preferably removed from the airflow prior to reaching the exhaust opening of the apparatus disclosed herein.
Avoidance of the production of nitrogen dioxide and associated compounds is a preferable path and an embodiment to accomplish such an end is also disclosed. A well-established technology known as “pressure swing adsorption” (PSA), may be employed. Pressure swing adsorption is commonly used in oxygen concentrators to separate nitrogen from oxygen. This process is used to reduce the concentration of nitrogen available for formation of nitrogen oxides in the reactor space.
In a preferred embodiment for use within the reactor disclosed herein, the pressure swing adsorption equipment utilizes two vessels (tanks) that are capable of withstanding internal gas pressures of up to about 150 psi and preferably higher in some instances. While the first vessel is being pressurized the second vessel is depressurized, hence the reason for the use of the term “swing” in the name of the identified technology. Within each vessel, an adsorbent is used that has a high affinity for nitrogen, but not for oxygen, when pressurized. Aluminosilicate compounds called zeolites are among the most commonly used adsorbents in pressure swing adsorption for oxygen concentration.
In the first vessel, nitrogen is adsorbed by the zeolite which is positioned in the form of a bed at the base of the vessel, allowing a concentrated oxygen stream to pass through the bed and out the top. This concentrated oxygen stream can then be routed out of the top of the pressurized vessel and into the corona discharge device, reducing the formation of significant concentrations of nitrogen oxides, i.e., NO2, NO, N2O5, etc., and substantially increasing the concentration of ozone to levels between 1,000 and 60,000 parts per million produced within the corona discharge device. Once the zeolite has reached its maximum adsorption capacity for nitrogen, the first vessel must be regenerated to allow for further nitrogen adsorption. To do this, the inlet airstream is routed to the second vessel to ensure continuous operation while the first vessel is regenerated.
To regenerate the first vessel, the vessel is depressurized, causing the nitrogen to desorb from the surface of the zeolite. This desorbed stream containing concentrated nitrogen can then be safely released into the ambient atmosphere surrounding the pressure swing adsorption vessels without harm to human health because nitrogen does not cause pulmonary distress as do nitrogen oxides. The process is completed again for the second vessel once the maximum nitrogen adsorption capacity is reached, switching the inlet airstream to the newly regenerated first vessel to maintain constant oxygen production. Typically, the oxygen concentration leaving a pressure swing adsorption oxygen concentrator is greater than 90%, but not more than 99%. Some pressure swing adsorption units can generate oxygen at lower concentrations, such as 50% purity.
It is contemplated by this disclosure in at least one embodiment that a portion of the overall airstream passing through the corona discharge device is the oxygen continuously routed from the vessels of the pressure swing adsorption unit. Some nitrogen will be present in the airstream entering the corona discharge device, allowing for minimal creation of nitrogen oxides that will stay below the safe maximum concentration limit set by the U.S. Environmental Protection Agency (U.S. EPA). To minimize the production of nitrogen dioxide and other nitrogen-based pollutants in the corona discharge device, an optimal configuration would maximize the delivery of oxygen from the pressure swing adsorption unit and minimize the delivery of ambient air that passes between the plates of the corona discharge device.
In a second embodiment of the device, an ultraviolet (UV) lamp is used to produce ozone. UV lamps produce ozone in the same manner that ozone is produced in the environment, with UV light contacting diatomic oxygen, causing the oxygen to split into two atomic oxygen atoms. These atoms react with additional diatomic oxygen molecules to form ozone. UV light is classified based on its wavelength, with ranges defined by the World Health Organization (WHO) of UV-A at 315 to 400 nm, UV-B at 280 to 315 nm, and UV-C at 100 to 280 nm. Ozone production from UV light occurs at wavelengths of around 185 nm. Typically, most commercial UV lamps consider ozone an undesirable by-product, so these lamps use a coating to block the release of wavelengths around 185 nm. In UV lamps used for ozone production, these wavelengths are maximized.
UV lamps produce light by passing electricity through a gas such as mercury. To do this, a device called a ballast converts a lower input voltage into a higher output voltage that travels across the lamp, from one electrode to another. This allows the mercury gas between the electrodes to be excited by the electricity to produce UV light. More recently, UV LEDs have also been proposed for producing UV light, although their cost has limited their use. UV lamps such as those containing mercury or argon are not selective with the type of UV light produced and must be optimized for a desired wavelength range, whereas UV LEDs can be tailored to release a very small subset of wavelengths.
Unlike corona discharge devices, UV lamps or UV LEDs produce little to no nitrogen oxides, as the wavelength of UV that splits diatomic oxygen to form ozone does not split diatomic nitrogen. This is the main benefit of producing ozone with UV lamps or UV LEDs. However, corona discharge devices are more efficient at producing ozone, capable of producing much larger quantities for a given air flow rate. Thus, careful selection of the ozone generating device is required to meet the desired application.
As an additional benefit, UV light has disinfectant properties, and is commonly used as a disinfection method. Typically, UV-C is used to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions. The ultraviolet light embodiment preferably utilizes a UV-C germicidal lamp that releases wavelengths of light from 150 to 280 nm, typically producing between 2.5 and 20 g/hour of ozone in a 200-cubic foot per minute (CFM) airstream. The size of the ultraviolet lamp for ozone production may be scaled accordingly to accommodate larger volumes.
Once the ozone generating device has generated the desired concentration of ozone, mixing baffles serve to thoroughly mix the airstream to increase the exposure of the pathogens to the ozonated air and to commensurately increase the potential for inactivation of the pathogens. A more complex configuration of baffles is also contemplated by this disclosure and may include additional suspended plates or rods to generate increased turbulence.
Following the mixing baffles, the disclosed apparatus utilizes a second ozone decomposition catalyst in the reactor that is used to convert ozone to oxygen. This catalyst will typically be the same as described in the alternative backflow preventer embodiment, with MnO2 coated on a monolithic substrate. Table 1 below reveals the results of testing of the ozone decomposition catalyst at 30 parts per million ozone and 100 linear feet per minute (LFM) air velocity, with varying numbers of 6-inch by 6-inch by 1-inch catalyst layers.
Data was also gathered under the same testing criteria for higher ozone concentrations and flow rates of 60 parts per million and 90 parts per million ozone and 100 LFM and 150 LFM with the number of catalyst layers adjusted to achieve 0.02 parts per million ozone or lower on the outlet/exhaust. Table 2 provides the results of testing with additional catalyst layers.
Following passage through the MnO2 catalyst the airstream is directed to an adsorbent for removing nitrogen oxides (NOx) created by the corona discharge device. Because nitrogen oxides such as nitrogen dioxide may adversely impact individuals with compromised pulmonary systems it is critical that the concentration of nitrogen oxides be reduced as much as possible. The preferred composition of the adsorbent consists of a third monolith containing an alkaline earth metal such as barium oxide coated on a substrate; however, other catalytic compositions are also contemplated by this disclosure.
Many compounds are known for their capacity to adsorb nitrogen oxides such as NO and NO2, including alkali and alkaline earth metals, activated carbons, molecular sieves, metal organic frameworks, zeolites, noble metals, soda lime (NaOH—CaO mixtures), and activated alumina. Although the preferred embodiment uses a monolithic substrate that can be coated with an NOx adsorbing compound, the adsorbent may also be used as a packed bed or in another configuration. At ozone concentrations higher than 1 part per million, nitrogen dioxide is the most common of the generated nitrogen oxides. Table 3 reveals the test results of the NOx adsorbing monolith in combination with the prior ozone decomposition catalyst, with 4 layers of the ozone decomposition catalyst coated with MnO2 followed by 4 layers of coated monoliths for adsorbing nitrogen oxides. Because all the NOx compounds were oxidized to NO2, the NO2 concentration was recorded.
In a preferred embodiment an exhaust filter may also be employed proximate the reactor's exhaust opening. This exhaust filter is employed to capture any particulates that may have eluded the pre-filter upon entry to the reactor space. Importantly, the exhaust filter is preferably not a filter with an exceedingly tight weave to avoid significantly obstructing the airflow. The filter is beneficial in capturing particulates and some de minimis percentage of still active pathogens that otherwise would have escaped into the space where the apparatus is located.
The apparatus as disclosed herein also preferably employs sensors to measure the concentrations of both ozone and nitrogen oxides. The preferred measurement locations being (i) proximate the ozone generating device, (ii) proximate the second ozone decomposition catalyst monolith utilized to convert ozone to oxygen; (iii) proximate the third adsorbent monolith for removing nitrogen oxides, and (iv) proximate the exhaust opening of the reactor. Sensors that are well known and widely available are employed to sense real-time concentrations of both ozone and NOx may also be connected to a data logger for maintenance of historical information on apparatus operation.
The apparatus as disclosed herein has undergone extensive testing to assess the efficacy of the device at removing aerosolized pathogens. In a test environment, the concentration of the viral RNA bacteriophage MS2 was measured prior to intake and upon exhaust from the apparatus to determine the percent pathogen destruction. MS2 is commonly used as a surrogate for the influenza virus and is now being considered as a possible surrogate for other RNA viruses such as SARS-CoV-2. This is due to SARS-CoV-2 being similar in size to influenza and to having an RNA genome.
A concentration of MS2 was aerosolized into a sealed environmental bioaerosol chamber containing the disclosed apparatus. An impinger instrument was used to collect samples of suspended particles in air at 0, 30, 60, 120 and 180 minutes in the chamber. All impinger samples were serially diluted, plated, and enumerated in triplicate to yield viable bioaerosol concentrations at each sampling point and time. Chamber control trial data was subtracted from the trial data to yield net LOG reduction in pathogen concentrations. The apparatus showed a consistent net LOG reduction throughout the trial with almost a full net LOG reduction at each time interval.
The average net LOG reduction went from 1.03 at the 30-minute interval to 4.12 at the 180-minute interval. A net LOG reduction over 4.00 in 180 minutes indicates the efficacy of the disclosed apparatus against the MS2 bacteriophage. See Table 4 below for a summary of the average net LOG reduction of MS2 by the device disclosed herein. The study was conducted in compliance with FDA Good Laboratory Practices which is defined at 21 CFR, Part 58.
During the trials conducted in a sealed environmental bioaerosol chamber, the room levels of ozone were also measured. See Table 5 for the Lowest, Highest, and Average output measurements of ozone across all four trials. The concentration of ozone at the exhaust opening and in the overall sealed chamber was maintained at a lower concentration than that mandated by the National Ambient Air Quality Standards (NAAQS) at 40 CFR § 50.19.
Additional testing conducted at MRIGlobal in February of 2021 showed that the apparatus disclosed herein had a high level of aerosol viable virus reduction of SARS-CoV-2 (the cause of COVID-19) over 99.7% for all conducted tests (maximum reduction of 99.974% for the 500 mg/m3 ozone test) with a reactor flow through residence of less than 14 seconds and an ozone generation rate ranging between 250 and 1,000 mg/m3 as seen in Table 6 below. The table provides that with a full turnover of air in the enclosed space, the apparatus provides an achievable net LOG reduction of active airborne pathogens within a room in the range of 4.0 to 5.0 with the net LOG reduction per pass through the device being between 2.6 to 3.4. TCID50 in the table below refers to the method used to quantify the concentration of viruses used in the test and AGI-30 refers to the type of impinger.
It is an object of the apparatus disclosed herein to inactivate a high percentage of airborne pathogens prior to discharging the exhausted air.
It is a further object of the apparatus as disclosed herein to economically inactivate the airborne pathogens prior to discharge from the apparatus.
It is a further object of the apparatus as disclosed herein to minimize the volume and concentration of ozone that is discharged from the apparatus to the occupied space.
It is a further object of the apparatus as disclosed herein to minimize the volume and concentration of nitrogen oxides that are discharged from the apparatus to the occupied space.
It is a further object of the apparatus as disclosed herein to scale the apparatus to inactivate pathogens in venues of any volume.
It is a further object of the apparatus as disclosed herein to inactivate airborne pathogens on a personal mobility level such that the apparatus is linked to a breathing apparatus capable of intaking ambient air and supplying it to a breathing apparatus on a personal scale.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements.
The detailed description of exemplary embodiments herein refers to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the inventions, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the inventions.
The detailed description herein is presented for purposes of illustration only and not of limitation. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.
To inactivate pathogens, the apparatus as disclosed herein produces ozone using either a corona discharge device in conjunction with an oxygen concentrator or one or more UV-C lamps. The ozone mixes with pathogens in the airstream, causes them to be inactivated. Once the pathogens are inactivated, ozone and any other by-products such as nitrogen oxides are removed. The apparatus has undergone extensive testing to ensure uniform ozone production, high pathogen inactivation, and removal of both ozone and nitrogen oxides.
The mg/m3 ratings for ozone generators are measured when they are used with a concentrated oxygen supply of 90% to 99%. Since ambient air contains only around 21% oxygen, ozone generators often produce far less ozone than the rating supplied by their manufacturer. To account for this and other environmental conditions, sensors for Temperature (° C.), Relative Humidity (%), and Ozone (PPM) were built into the Test Device. As seen in
Concentrations of ozone below 25 parts per million have likewise been shown in published academic studies to inactivate over 99% of airborne pathogens. One study in particular—Chun-Chieh Tseng & Chih-Shan Li (2006) Ozone for Inactivation of Aerosolized Bacteriophages, Aerosol Science and Technology, 40:9, 683-689, published by the American Association for Aerosol Research, disclosed that for 99% virus inactivation of phi 6, phi X174, MS2, and T7 required ozone doses of 2.50 parts per million, 3.84 parts per million, 6.63 parts per million, and 10.33 parts per million, respectively with a contact time of 13.8 seconds.
The apparatus 10 as illustrated in
The apparatus 10, as further illustrated in
The reactor 12 has an intake opening 14 and an exhaust opening 16. Ambient air 18 is drawn into the reactor 12 through the intake opening 14 and after passing through the various zones of the reactor 12 passes out through the exhaust opening 16 with a high percentage of the airborne pathogens inactivated and therefore substantially reducing the potential for infecting those in the surrounding spaces.
As shown in
As illustrated in
Ozone generation occurs in area 40 interior to the reactor 12 away from the intake opening 14 and beyond the backflow preventer 26. In this area 40, as illustrated at
In operation, the fan 20 moves the airstream 98 into the space gap 44 between the corona discharge plates 50 where the high voltage, high frequency and alternating current results in the generation of ozone molecules 76. It is ozone that serves to inactivate the airborne pathogens within the reactor 12. In an alternative embodiment, as further illustrated in
Alternative cooling of the heat sink such as with a supplemental fan or water-cooling device yields even higher ozone concentrations and therefore increased inactivation of airborne pathogens. The methodologies described above for cooling the corona discharge device 42 are all contemplated by this disclosure.
An alternative embodiment of the apparatus 10 employs a corona discharge device 42 in combination with an oxygen concentrator 54 utilizing “pressure swing adsorption.” An exemplary oxygen concentrator configuration is shown in
With a substantially reduced percentage of nitrogen passing between the plates 50 of the corona discharge device 42 there is a greatly reduced potential for nitrogen oxides to be produced from the corona discharge device 42. Since nitrogen oxides are considered air pollutants and are regulated by the U.S. Environmental Protection Agency at 40 CFR § 50.11, there is a human health based reason, specifically a pulmonary concern, to increased exposure to high concentrations of nitrogen oxides. The 8-hour standard for the National Primary ambient air quality standard for nitrogen oxides codified at 40 CFR § 50.11 provides that the concentration of nitrogen oxides in the ambient air shall not exceed 53 parts per billion and the one-hour standard provides that the concentration of nitrogen oxides shall not exceed 100 parts per billion. The airstream 98 exiting the apparatus 10 as disclosed herein ejects the airstream to the ambient air 18 with a concentration of nitrogen oxides less than 100 parts per billion.
As illustrated in
Once zeolite 62 has adsorbed a maximum concentration of nitrogen 66, the left vessel 58 is pressurized and the process is repeated within the left vessel 58. As shown in
It is contemplated by this disclosure that, in at least one embodiment, a portion of the overall airstream passing through the corona discharge device 42 is the oxygen continuously routed from the vessels of the oxygen concentrator 54. With highly purified oxygen entering the corona discharge device 42 from the oxygen concentrator 54 the corona discharge device 42 is capable of producing ozone at concentrations ranging from 1,000 to 60,000 parts per million. This highly concentrated ozone is commingled with the airstream 98 passing through the reactor 12 thereby reducing the overall concentration of ozone for inactivating the pathogens. To minimize the production of nitrogen dioxide and other nitrogen oxides in the corona discharge device 42 an optimal configuration directs the delivery of oxygen 64 from the oxygen concentrator 54 and minimizes the delivery of ambient air that passes through the plates 50 of the corona discharge device 42. The rationale for this being that ambient air contains roughly 78% nitrogen while the gas supplied by the oxygen concentrator 54 contains a very high percentage of oxygen 64 with little nitrogen 66 available for conversion to nitrogen oxides in the corona discharge unit.
In another embodiment, the oxygen concentrator 54 utilizes a continuously variable control valve, also known as a proportional isolation valve 71, is illustrated at
This embodiment may also employ a microcomputer, a microcontroller, or a programmable logic controller 70A that is in communication with the valve 71 to control the volumetric flow of oxygen 64 through the valve 71 to the corona discharge device 42. Implementation of such controllers is well known in the industry and need not be detailed herein. Fine variable control of the valve 71 facilitates control of the production of ozone by the corona discharge device 42 as well as limiting the production of nitrogen oxides. An exemplary programmable logic controller 70A for use in this application is sold by Clippard such as the SCPVD-1 Stepper-Controller Proportional Valve Driver.
This fine level of control is accomplished by utilizing the valve 71 to balance the displacement of ambient air with oxygen 64 from the oxygen concentrator 54. Signals from the ozone and nitrogen oxides sensors (discussed in greater detail below) mounted within the reactor 12 will provide input to the programmable logic controller, microcomputer, or microcontroller to optimize operational inflow of oxygen 64 to the corona discharge device 42.
Another embodiment contemplated by the disclosure for ozone generation within the reactor 12 is by using ultraviolet light. Lamps that produce ozone from ultraviolet light maximize the production of wavelengths around 185 nm. These lamps also produce many other wavelengths of light in the UV-C spectrum. In contrast to ozone generators using corona discharge, UV-C lamps produce little to no nitrogen oxides, although they are less efficient, producing smaller concentrations of ozone for a given airstream. The ultraviolet light embodiment preferably utilizes UV-C germicidal lamps that produce, for example, between 2.5 to 20 g/hour of ozone and with an airflow rate of about 200 CFM for a 500 to 1,500 ft3 space in a residence, office, or industrial setting.
The size of the UV-C device may be scaled accordingly to accommodate larger volumes. Multiple vendors produce UV-C lamps that can produce up to 3 g/hour of ozone. As illustrated in
Following generation of the ozone 76, the ozonated and the pathogen laden air is moved over and around at least one baffle 78 within the reactor 12 to provide for thorough mixing and contact of the pathogens with ozone. The concentration of ozone 76 within the reactor 12, proximate the ozone generator, is in the range of 1 to 55 parts per million, a concentration that is sufficient to inactive a very high percentage of the airborne pathogens transiting through the reactor 12. A single plate baffle 78 with multiple channels or a plurality of long cutouts may suffice to create the desired mixing. Multiple baffles in series are also contemplated to achieve thorough mixing; however, with increasing baffle placement comes the need for increased fan output to drive the airflow through the reactor. Additional baffle configurations are contemplated by this disclosure and multiple configurations may be employed to increase the exposure of the pathogens to ozonated air. As indicated above, when the airborne pathogens are exposed to an ozone concentration of between 1 and 55 parts per million, they are rapidly inactivated by such exposure.
Once thorough mixing has been completed and sufficient residence time has passed for the ozone to inactivate the pathogens in the airstream, the airstream containing the inactivated pathogens and their components and any excess ozone 76 is exposed to an ozone conversion decomposition catalyst 82 for converting the ozone 76 to oxygen. It is critical to remove as much ozone as possible from the airstream because ozone is considered an air pollutant according to federal regulation at 40 CFR § 50.19 and exposure of 1 hour is limited to a concentration no greater than 70 parts per billion.
As illustrated in
Once the airstream 98 advances beyond the ozone decomposition catalyst 82 it may still be laden with nitrogen dioxide and other associated nitrogen oxides, i.e., NO, N2O5, etc., that are harmful to human pulmonary function. Both the ceramic and metallic monolithic substrates 88 as shown in
In a preferred embodiment, several ozone decomposition catalyst monoliths 88 are placed before the nitrogen oxides adsorbing monoliths 100 to ensure that ozone does not compete with nitrogen oxides for adsorption sites.
With the combined monoliths 88, 102 within a module 123 and the stacking of such modules, both the ozone decomposition catalyst monoliths 88 and the NOx adsorption monoliths 100 are preferably positioned within the reactor 12 in such a manner that they can be extracted from the reactor 12 through a slot 104, as illustrated at
Once the adsorption of the nitrogen oxides has been accomplished the airstream 98 optionally advances to an exhaust filter 110, such as illustrated at
The exhaust filter 110 is preferably in the range of a minimum efficiency reporting value (MERV) of 7-16 and is capable of trapping air particles in the 0.3 to 1.0-micron size range but of not such a high MERV rating that it is difficult for the apparatus 10 to exhaust the airstream 98 out of the reactor 12. The exhaust filter 110 is preferably disposed within the reactor 12 in such a manner as with the ozone decomposition catalyst monolith 82 and NOx adsorbent monolith 100 that it can be readily removed from the reactor for replacement or cleaning.
As illustrated at
These concentration measurements are beneficial in alerting the operator to the proper operation of the apparatus 10 and whether maintenance, or system tuning, may be required to adjust the concentration of ozone produced by the apparatus. When an oxygen concentrator 54 is used, the data from these sensors may optionally but preferably be fed to a microprocessor, microcontroller, or a programmable logic controller 70A for adjusting as necessary, the continuously variable control or proportional control valve 71 that feeds oxygen from the oxygen concentrator 54 as illustrated at
If the concentration of ozone in the airstream 98 exiting the apparatus is higher than the maximum concentration limit, the sensor 116, 118 relays to the microcomputer, PLC, or microcontroller 70A the measured concentration, and a pre-programmed instruction is executed by the control device 70A to reduce the magnitude of ozone produced by the ozone generator 42. Similarly, if the concentration of nitrogen oxides, whether nitrogen dioxide or any similar compound, exceeds a set maximum concentration limit as measured by the designated sensor 118, the ozone generator 42 in concert with the oxygen concentrator 54 can adjust flow rate accordingly to increase the output of the oxygen concentrator or reduce the output of the ozone generator. Other electronic components may be used in combination with those described above to ensure proper control of ozone and nitrogen oxides, such as printed circuit boards, transistors, capacitors, resistors, and diodes.
As illustrated in
The airstream 98 carrying a high percentage of inactivated pathogens then flows past the ozone decomposition catalyst 82 to convert ozone 76 in the airstream to oxygen and past the NOx adsorption monolith 100. Finally, the airstream 98 passes through the exhaust filter 110, around the heating and cooling elements 132, 134, and out the exhaust opening 16. Ozone and nitrogen oxides sensor banks 116, 118, and 120 disposed within and around the reactor 12 monitor the concentration of ozone and nitrogen oxides leaving the apparatus to ensure the maximum concentration limits set by the U.S. EPA are not exceeded. Throughout the process, the fan 20 pulls the airstream 98 through the reactor 12 and out the exhaust opening 16.
In an alternative configuration for integration in HVAC ducting, the heating 132 and cooling 134 elements may also be placed within the reactor 12, as opposed to after the reactor 12.
The reactor 12 contains an inlet pipe or tubing for injection of ozone 76 from the oxygen concentrator 54 fed corona discharge 42 or UV-C ozone generator 74. The oxygen concentrator releases a highly concentrated stream of oxygen into the space surrounding the corona discharge generator 42 or UV-C ozone generator 74, limiting the production of NOx compounds and increasing the production of ozone. Once the ozone 76 is injected into the airstream, the airstream passes over the baffles which increase mixing and improves pathogen inactivation, until moving to the ozone decomposition catalyst which removes the ozone.
As shown in
In a final embodiment, the configuration as illustrated at
The disclosed apparatus, and systems should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The disclosed apparatus and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present or problems be solved.
In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only examples of the disclosure and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope of these claims.
The disclosure presented herein is believed to encompass at least one distinct invention with independent utility. While the at least one invention has been disclosed in exemplary forms, the specific embodiments thereof as described and illustrated herein are not to be considered in a limiting sense, as numerous variations are possible. Equivalent changes, modifications, and variations of the variety of embodiments, materials, compositions, and methods may be made within the scope of the present disclosure, achieving substantially similar results. The subject matter of the at least one invention includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions and/or properties disclosed herein and their equivalents.
Benefits, other advantages, and solutions to problems have been described herein regarding specific embodiments. However, the benefits, advantages, solutions to problems, and any element or combination of elements that may cause any benefits, advantage, or solution to occur or become more pronounced are not to be considered as critical, required, or essential features or elements of any or all the claims of at least one invention.
Many changes and modifications within the scope of the instant disclosure may be made without departing from the spirit thereof, and the one or more inventions described herein include all such modifications. Corresponding structures, materials, acts, and equivalents of all elements in the claims are intended to include any structure, material, or acts for performing the functions in combination with other claim elements as specifically recited. The scope of the one or more inventions should be determined by the appended claims and their legal equivalents, rather than by the examples set forth herein.
Benefits, other advantages, and solutions to problems have been described herein regarding specific embodiments. Furthermore, the connecting lines, if any, shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions.
The scope of the inventions is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a feature, structure, or characteristic, but every embodiment may not necessarily include the feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a feature, structure, or characteristic is described relating to an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic relating to other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4343765 | Elston et al. | Aug 1982 | A |
| 4370301 | Doi et al. | Jan 1983 | A |
| 5681533 | Hiromi | Oct 1997 | A |
| 5961919 | Tachibana et al. | Oct 1999 | A |
| 6312606 | Conrad | Nov 2001 | B1 |
| 6528023 | Fleischer | Mar 2003 | B2 |
| 6537484 | Nakagawa et al. | Mar 2003 | B2 |
| 6558636 | Tamura et al. | May 2003 | B2 |
| 6589486 | Spanton | Jul 2003 | B1 |
| 6605260 | Busted | Aug 2003 | B1 |
| 6620379 | Piuk et al. | Sep 2003 | B1 |
| 6620380 | Thomas et al. | Sep 2003 | B2 |
| 6630105 | O'Neill et al. | Oct 2003 | B1 |
| 6635153 | Whitehead | Oct 2003 | B1 |
| 6652816 | Hwang | Nov 2003 | B2 |
| 6680033 | Ishii | Jan 2004 | B2 |
| 6682707 | Chao | Jan 2004 | B2 |
| 6764659 | Perlov et al. | Jul 2004 | B2 |
| 6793897 | Shannon | Sep 2004 | B2 |
| 6824693 | Sauska et al. | Nov 2004 | B1 |
| 6866828 | Segawa et al. | Mar 2005 | B2 |
| 6872366 | Thomas et al. | Mar 2005 | B2 |
| 6893618 | Kotlyar | May 2005 | B2 |
| 6967008 | Barnes | Nov 2005 | B1 |
| 6974560 | Taylor et al. | Dec 2005 | B2 |
| 6984361 | Carman et al. | Jan 2006 | B2 |
| 6991768 | Keras et al. | Jan 2006 | B2 |
| 7098462 | Chua et al. | Aug 2006 | B2 |
| 7121079 | Calvo et al. | Oct 2006 | B2 |
| 7250145 | Miller et al. | Jul 2007 | B1 |
| 7326387 | Arts et al. | Feb 2008 | B2 |
| 7407624 | Cumberland et al. | Aug 2008 | B2 |
| 7407633 | Potember et al. | Aug 2008 | B2 |
| 7438870 | Anno | Oct 2008 | B2 |
| 7588720 | Turcot et al. | Sep 2009 | B2 |
| 7604774 | Mole et al. | Oct 2009 | B2 |
| 7604780 | Teran et al. | Oct 2009 | B2 |
| 7608217 | Champagne | Oct 2009 | B2 |
| 7901618 | McVey et al. | Mar 2011 | B2 |
| 7943098 | Phillips et al. | May 2011 | B2 |
| 8038936 | Sim et al. | Oct 2011 | B2 |
| 8105546 | Lanz | Jan 2012 | B2 |
| 8128869 | Sunderland | Mar 2012 | B2 |
| 8211208 | Chan et al. | Jul 2012 | B2 |
| 8211374 | Hallam | Jul 2012 | B2 |
| 8221678 | Hedman | Jul 2012 | B2 |
| 8236236 | Garner | Aug 2012 | B2 |
| 8241563 | Kolve et al. | Aug 2012 | B2 |
| 8318084 | Johnson et al. | Nov 2012 | B2 |
| 8329096 | Elrod et al. | Dec 2012 | B2 |
| 8337759 | Alford et al. | Dec 2012 | B1 |
| 8354057 | Heselton | Jan 2013 | B2 |
| 8357331 | McVey et al. | Jan 2013 | B2 |
| 8361402 | Tsui | Jan 2013 | B2 |
| 8367010 | Chen et al. | Feb 2013 | B2 |
| 8388900 | Benedek et al. | Mar 2013 | B2 |
| 8549994 | Mole | Oct 2013 | B2 |
| 8627531 | Ninomiya et al. | Jan 2014 | B2 |
| 8667817 | Smith et al. | Mar 2014 | B2 |
| 8747763 | Tandou et al. | Jun 2014 | B2 |
| 8758679 | Hyde et al. | Jun 2014 | B2 |
| 8845782 | Metteer | Sep 2014 | B2 |
| 8865065 | Kain et al. | Oct 2014 | B2 |
| 8992837 | Jung et al. | Mar 2015 | B2 |
| 9034249 | Foreman et al. | May 2015 | B2 |
| 9119892 | Mueller et al. | Sep 2015 | B2 |
| 9205166 | Segura Rius et al. | Dec 2015 | B2 |
| 9216233 | Ota et al. | Dec 2015 | B2 |
| 9233183 | Kim | Jan 2016 | B2 |
| 9474822 | Jung et al. | Oct 2016 | B2 |
| 9509125 | Waddell et al. | Nov 2016 | B2 |
| 9610559 | Riskin et al. | Apr 2017 | B2 |
| 9711317 | Weibel et al. | Jul 2017 | B2 |
| 9987388 | Jurak et al. | Jun 2018 | B2 |
| 10010644 | Burnett | Jul 2018 | B2 |
| 10143763 | Campalans | Dec 2018 | B2 |
| 10265432 | Paranhos et al. | Apr 2019 | B2 |
| 10281168 | Meirav et al. | May 2019 | B2 |
| 10363522 | Bender et al. | Jul 2019 | B2 |
| 10386080 | Lee et al. | Aug 2019 | B2 |
| 10478517 | Hauville et al. | Nov 2019 | B2 |
| 10581227 | Haruna et al. | Mar 2020 | B2 |
| 10583213 | Stibich et al. | Mar 2020 | B2 |
| 10675375 | Jiang | Jun 2020 | B2 |
| 10729801 | Woodbridge | Aug 2020 | B2 |
| 10739023 | Buske et al. | Aug 2020 | B2 |
| 10933158 | Benedek | Mar 2021 | B2 |
| 10988270 | Gorbatenko et al. | Apr 2021 | B2 |
| 20040262241 | Socha | Dec 2004 | A1 |
| 20080175671 | Bowman | Jul 2008 | A1 |
| 20150297771 | Law | Oct 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 109631195 | Apr 2019 | CN |
| Entry |
|---|
| U.S. Appl. No. 63/019,522, filed May 4, 2020, 31 pages. |
| U.S. Appl. No. 63/003,344, filed Apr. 1, 2020, 39 pages. |
| U.S. Appl. No. 62/944,397. |
