Abstract:
Some embodiments of the present disclosure provide an air treatment assembly including a sorbent, such as a carbon fiber cloth, for cleansing circulating indoor air of VOCs. Accordingly, in some embodiments, the air treatment assembly is provided and may be configured for in-situ regeneration, using outside air to flush a sorbent and purge the air treatment assembly in a repeatable adsorption-regeneration cycle, allowing a relatively small mass of sorbent to be used for an extended period of time.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to: U.S. Provisional Patent Application No. 61/622016, filed Apr. 10, 2012 and entitled “Air Cleaning Assembly”; U.S. Provisional Patent Application No. 61/704815, filed Sep. 24, 2012 and entitled “Volatile Organic Compound Remover Assembly” and U.S. Provisional Patent Application No. 61/703739, filed Sep. 20, 2012 and entitled “Method and System for Monitoring Indoor Air Quality”. The disclosures of the above applications are incorporated herein by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    Embodiments of the present disclosure generally relate to air treatment and more particularly to Volatile Organic Compound (VOC) removal from indoor environments. 
       BACKGROUND 
       [0003]    Indoor air within and around buildings and other closed spaces is affected by a plurality of contaminants. Among these contaminants are a group of species of organic vapors, broadly referred to as Volatile Organic Compounds (VOC). The sources of these vapors include, inter alia, the human occupants themselves—from respiration and perspiration to clothing and cosmetics—as well as building materials, equipment, food and consumer products, cleaning materials, office supplies or any other materials emitting VOCs. Other contaminant include inorganic gases such as carbon dioxide (CO 2 ), nitrous oxides, carbon monoxide, sulfur dioxide, ozone, radon, and others, as well as particles and microorganisms. 
         [0004]    Indoor air is normally managed by Heating, Ventilation and Air-Conditioning (“HVAC”) systems. One of the goals of HVAC systems is to provide a comfortable and healthy environment for building occupants, in terms of temperature, humidity, composition and cleanliness of air. HVAC systems constantly circulate air through the building while continually adjusting its temperature and humidity to maintain a comfortable environment. 
         [0005]    It is desirable to reduce VOC levels in indoor air, and ideally to do so without constantly having to replace the air by exhausting indoor air and injecting fresh air. 
       SUMMARY OF DISCLOSURE 
       [0006]    In some embodiments of the present disclosure, an air treatment assembly is provided with a carbon fiber cloth for cleansing circulating indoor air of VOCs. Accordingly, in some embodiments, the air treatment assembly is provided, which may be configured for in-situ regeneration, using outside air to flush a sorbent and purge the air treatment assembly in a repeatable adsorption-regeneration cycle, allowing a relatively small mass of sorbent to be used for an extended period of time. The regeneration process can be enhanced or accelerated by heating the purge air of the sorbent itself. Other sorbents, catalysts, ions or radiation can be added, for example, to improve removal of certain VOC species or remove other contaminants such as CO 2  or microorganisms. 
         [0007]    There is thus provided in accordance with an embodiment of the disclosure an air treatment assembly for reducing VOCs contained in indoor air from an enclosed environment, comprising at least one layer of VOC adsorbent filter supported by a rigid frame or a mesh, an enclosure retaining the VOC adsorbent filter and configured to allow air to flow through the filter, whereby at least some of the VOCs are adsorbed, and a plurality of ports having a plurality of dampers together configured for at least two operation modes including an indoor mode of operation , wherein indoor air is treated for VOC removal, and a filter regeneration mode for in-situ regeneration of the VOC adsorbent filter by a purge gas, and exhausting the purge gas outside of the enclosed environment. 
         [0008]    According to some embodiments, the VOC adsorbent filter comprises a carbon fiber cloth comprising a woven fabric or a sheet of intertwined carbon fibers. The carbon fiber cloth may be generally flat. Alternatively, the carbon fiber cloth may be pleated. The enclosure may include a rigid frame, wherein the carbon fiber cloth is supported in the rigid frame. 
         [0009]    According to some embodiments, the purge gas comprises outside air. The purge gas may be introduced at a temperature between about 20° C. to about 120° C. The purge gas may be heated by at least one of an electric coil, a hot water coil, a gas furnace, a heat pump, solar heat, and waste heat from a nearby source. The carbon fiber cloth may be heated during the filter regeneration mode by an electric current or by radiation. 
         [0010]    According to some embodiments, at least one regenerable sorbent material other than the carbon fiber cloth may be present and configured to remove contaminants from the indoor air and for in-situ regeneration using a purge gas. The additional sorbent may be configured to remove CO 2  from indoor air. The additional sorbent may be a solid supported amine. 
         [0011]    There is thus provided in accordance with an embodiment of the disclosure, a permeable air filtration cartridge comprising a rigid frame, at least one sheet of carbon fiber or carbon fiber cloth supported by the frame, and at least one additional solid sorbent material capable of in-situ regeneration, supported by the rigid frame. The additional sorbent material may comprise a granular solid supported by the mesh, and wherein the mesh may be configured to hold the sorbent material and allow air to flow through the cartridge. The additional sorbent material may contain a solid supported amine. The additional sorbent material may be a molecular sieve, a clay, or a porous oxide. The sheet may line at least one interior surface of the cartridge. The cartridge may further comprise at least one additional catalyst material configured to induce a chemical change in at least one contaminant or molecular species in the indoor air. The cartridge may be configured for removable insertion into an air treatment assembly. 
         [0012]    There is thus provided in accordance with an embodiment of the disclosure, a method for reducing VOCs contained in indoor air from an enclosed residential or commercial environment, the method comprising providing the air treatment assembly for removing VOCs from indoor air, streaming indoor air containing VOCs from inside the enclosed residential or commercial environment through the assembly, such that the assembly captures at least some of the of the VOCs from the indoor air, and streaming a purge gas, containing less VOCs than the indoor air , through the assembly such that the assembly releases at least some of the captured VOCs to the purge gas. 
         [0013]    According to some embodiments, the purge gas may be outdoor air. The purge gas may comprise outside air having a temperature in the range of between about 30° C. to about 120° C. The purge gas may comprise outside air with a temperature less than about 80° C. The purge gas may comprise outside air with a temperature less than about 50° C. 
         [0014]    There is thus provided in accordance with an embodiment of the disclosure, a control system for controlling the air treatment assembly, comprising a processor having computer instructions operating thereon for controlling one or more of the dampers, fans and heaters/conditioners associated with the assembly, the instructions comprising instructions for at least the indoor air mode and the filter regeneration mode. 
         [0015]    There is thus provided in accordance with an embodiment of the disclosure, an air treatment monitoring system for monitoring the air treatment assembly comprising one or more VOC sensors configured to monitor concentration of VOCs in the air, wherein one or more electronic signals from the one or more sensors are transmitted to the monitoring system and comprise at least one of: inputs for the control system to determine if the air treatment assembly needs to be regenerated, serviced or turned off or on; data for recording and/or monitoring air quality; and data for recording the performance of the air treatment assembly. 
         [0016]    According to some embodiments, the VOC sensors may comprise photoionization detectors. Additionally, the VOC sensors may comprise metal oxide sensors. Furthermore, the VOC sensors may comprise differential mobility spectrometers. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0017]    The principles and operations of the systems, apparatuses and methods according to some embodiments of the present disclosure may be better understood with reference to the drawings, and the following description. These drawings are given for illustrative purposes only and are not meant to be limiting. 
           [0018]      FIGS. 1A-1C  are each a schematic illustration of an air treatment assembly for reducing VOCs according to some embodiments of the present disclosure; 
           [0019]      FIGS. 2A-2C  are each a schematic illustration of an air treatment assembly for reducing VOCs according to some embodiments of the present disclosure; and 
           [0020]      FIG. 3  is a schematic illustration of an air treatment assembly for reducing VOCs according to some embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Reference is made to  FIGS. 1A-1C , which are each a schematic illustration of an air treatment assembly  100  comprising a VOC adsorbent filter  102  for reducing one or more VOCs in an airflow. Reduction of VOCs may be performed by carbon cloth filters (CCF) formed as, for example, activated carbon fiber cloths  108 , or any other suitable means. 
         [0022]    The carbon fiber cloth  108  may comprise a woven fabric or a sheet of intertwined carbon fibers. Activated carbon fiber cloths  108  may be commercially available, for example, as the FM-10 ZORFLEX® ACC carbon fiber cloth of Calgon Carbon Corporation. The supple carbon fiber cloth  108  can be formed into uncurved, flat sheets with a relatively flat, straight surface  110  and supported by a frame or a mesh  112 , which may be a substantially rigid frame or mesh (mesh, screen and/or other permeable surface; these terms/phrases being used interchangeably), as seen in  FIG. 1A . In some embodiments, the carbon fiber cloth  108  can be laminated with a permeable material  116 , like filter paper or synthetic fibers, to give it more structural strength, stiffness or protection from dust particles. 
         [0023]    In some embodiments, with or without lamination, the carbon fiber cloth  108  can be pleated in an accordion-like form  120 , as seen in  FIG. 1B . The pleated or curved cloth may also be supported by the frame or mesh  112 . In some embodiments, the pleating may increase the surface area and reduce the pressure drop of the flowing air. 
         [0024]    In some embodiments, flat or pleated carbon fiber cloths  108  can be inserted into an enclosure  130  comprising a framed (e.g., rectangular) sheet. The enclosure  130  can be constructed of any sufficiently rigid material, such as metal or plastic. In some embodiments, the enclosure  130  may comprise an aluminum frame. In some embodiments, the enclosure  130  may comprise plastic polymers. In some embodiments, the enclosure  130  may comprise frames based on paper, cardboard or recycled materials. 
         [0025]    As seen in  FIGS. 1A-1C , for example, in some embodiments, the enclosures  130  may be formed as rectangular (for example) sheets; one of skill in the art will appreciate that enclosures comprising frames (and corresponding sheets) may be configured in any suitable configuration. In some embodiments, the enclosures  130  may be formed of a permeable material or configuration for allowing air to flow therethrough. 
         [0026]    In some embodiments, the carbon fiber cloth  108  may be formed into one of several commonly used three dimensional filter forms, including but not limited to a V-bank shape. As seen in  FIG. 1C , for example, a plurality of carbon fiber cloths  108  supported by enclosures  130  may be provided and arranged in a V-bank arrangement (for example). Supporting walls  134  may also be provided to support the plurality of carbon fiber cloths  108 , as shown in  FIG. 1C . 
         [0027]    In some embodiments, the carbon fiber cloth  108  may be formed as a cylindrical filter (not shown), where air flows radially between an inside and outside surface of the cylinder (for example). 
         [0028]    In some embodiments, multiple layers of the carbon fiber cloth  108  can be used to increase the efficiency and capacity of VOC adsorption. Several layers of carbon fiber cloths  110  (e.g., flat, or textured—i.e., with a topography) and/or several layers of pleated carbon fiber cloths  120  can be positioned in parallel, in the same enclosure  130  (for example), as shown in  FIG. 2B . In some embodiments, several separately framed layers of carbon fiber cloths  108  (flat, pleated, and/or having a surface topography) can be positioned in series so that air flows through them in sequence, as shown in  FIG. 1C . 
         [0029]    In any of these configurations, the VOC adsorbent filter  102  comprising the carbon cloth filter (CCF) may be part of the air treatment assembly  100 , illustrated in  FIGS. 1A-3 , the essential feature of which is the ability to regenerate the adsorptive capacity of the carbon fibers (for example). Some embodiments of the VOC adsorbent filter  102 , comprising a carbon fiber cloth  108 , is shown in  FIGS. 1A-3 . In  FIG. 1A , the VOC adsorbent filter  102  is shown as a flat carbon cloth  110  supported by a mesh or rigid frame  112  within the air treatment assembly  100 . The air treatment assembly  100  may be formed with multiple ports, including dampers, valves or shutters (such terms may be used interchangeably in the present application), and may be configured for at least two separate operational modes: at least one mode of operation comprising an indoor air mode where indoor air is treated for VOC removal, and at least one mode for regeneration of the VOC adsorbent filter  102 , where it is regenerated by purging the air treatment assembly  100  and exhausting the purge gas outside of an enclosed environment, as will be further described. The indoor air mode may also be referred to as an adsorption mode. 
         [0030]    Accordingly, in some embodiments, the carbon fiber cloth  108  may be placed in any suitable location within the air treatment assembly  100 . The carbon fiber cloth  108  may be arranged generally perpendicular to a flow orientation of incoming air  140 . 
         [0031]    A particle filter  144  may also be provided for removing dust and airborne particles from the incoming air  140 . The particle filter  144  may be formed of any suitable material, such as a filter paper or synthetic fiber cloth. The particle filter  144  may be placed in any suitable location within the air treatment assembly  100 , such as in proximity to an entry port  150 . The particle filter  144  may be omitted. 
         [0032]    The air treatment assembly  100  operates according to, in some embodiments, at least two operational modes. 
         [0033]    In normal, adsorption operation mode (e.g., indoor air mode), incoming air  140  enters through the entry port  150 , controlled by a damper  154 , whereby the incoming air  140  flows through the carbon fiber cloth  108  and exits via an exit port  156  controlled by a damper  158 . In some embodiments, the flow of air is urged by a fan  159  or a blower, which can be placed before or after the carbon fiber cloth  108 . In normal operation, the incoming air  140  flowing through the carbon fiber cloth  108  is indoor air originating from an enclosed environment. 
         [0034]    The enclosed environment may be an office building, a commercial environment or building, a bank, a residential environment or building, a house, a school, a factory, a hospital, a store, a mall, an indoor entertainment venue, a storage facility, a laboratory, a vehicle, an aircraft, a ship, a bus, a theatre, the cabin of a sea vessel, a partially and/or fully enclosed arena, an education facility, a library and/or other partially and/or fully enclosed structure and/or facility which can be at times occupied by equipment, materials, live occupants (e.g., humans, animals, synthetic organisms, etc.), etc., and/or any combination thereof and which has access to outside air. 
         [0035]    The cleaned air, exiting air treatment assembly  100  at exit port  156 , may be returned to the enclosed environment. The entire air treatment assembly  100  can be coupled directly to the enclosed environment or can be connected to ducts (not shown) used for heating, ventilation and air conditioning (HVAC). 
         [0036]    In some embodiments, the HVAC may be performed in a central HVAC system comprising a central air handling unit. In some embodiments, the HVAC may be performed in a distributed air circulation system comprising one or more fan-coil units. In some embodiments, the assembly may connect directly to the enclosed environment independently of any HVAC system or ductwork. 
         [0037]    When the carbon fiber cloth  108 , according to some embodiments, is in need of regeneration, the air treatment assembly  100  can be operated, in some embodiments, in a regeneration mode. For example, dampers  154  and  158  may be closed, effectively disconnecting the air treatment assembly  100  from the enclosed environment or the incoming air  140 . Purge gas  160  may then be injected though a separate entry port  170  controlled by a damper  174 . A fan  180  may be provided to urge the purge gas  160  to flow through the carbon fiber cloth  108  and exit via an exit port  184  and a damper  186 . 
         [0038]    In some embodiments, the purge gas  160  may comprise outside air, namely air brought from outside the building or other enclosed environment, injected through the air treatment assembly  100  and purged back to the outside of the building or enclosed environment. 
         [0039]    In some embodiments the purge gas  160  may comprise a gas containing less VOCs than the indoor air. 
         [0040]    The purge gas  160  may flow during the regeneration phase in the opposite direction of the flow of the incoming air  140 , from entry port  170  to exit port  184 , as shown in Figure lA (according to some embodiments). Alternatively, the purge gas  160  may flow during regeneration in the same direction of the incoming air  140  flow from exit port  184  to entry port  170  (according to some embodiments). 
         [0041]    In some embodiments, heat accelerates desorption. For example, the purge gas  160  can be introduced into the air treatment assembly  100  at ambient temperature or heated. The purge gas  160  may regenerate at a relatively low temperature in the range of 20-120° C. Alternatively, the purge gas  160  may regenerate at a temperature less than 80° C. Alternatively, the purge gas  160  may regenerate at a temperature less than 50° C. 
         [0042]    In some embodiments, heated purge gas  160  can be used to improve or accelerate the regeneration process. The purge gas  160  can be heated by any number of heat sources, including, for example, a gas furnace, an electric coil, a solar heater, a heat pump, or a coil with hot water or other hot fluid or waste heat from a nearby source. In some embodiments, the carbon fiber cloth  108  is heated directly by an electric current or by radiation such as light or infra-red light configured to reach the carbon cloth filter  100  during the regeneration process. 
         [0043]    Certain types of VOCs, including, but not limited to, light species, like formaldehyde and acetone, for example, may not be sufficiently adsorbed by the carbon fibers of the carbon fiber cloth  108  in certain operating conditions. These operating conditions may be, for example, temperature, air flow velocity, and concentration of these species. The removal of these species from the airflow can be further aided by means of catalyst materials that change the molecular structure of these species. In a non-limiting example, catalysts can turn light VOCs into heavier species that are better adsorbed. In another non-limiting example, catalysts can break down VOCs into smaller molecules like CO 2  and water. 
         [0044]    The air treatment assembly  100  according to some embodiments may comprise an access door  190  placed at any suitable location, providing access to the VOC adsorbent filter  102 . Accessibility may be provided for installation and/or removal of the VOC adsorbent filter  102  from the air treatment assembly  100 , such as when maintenance activities are required, typically wherein the VOC adsorbent filter  102  reaches the end of its prescribed operating life and needs to be replaced. 
         [0045]    In some embodiments, removal of other contaminants, such as CO 2 , requires a solid sorbent. The solid sorbent may comprise a granular sorbent or any other suitable sorbent. It has been previously described in applicant&#39;s US Patent Publication No. 20110198055, which is incorporated herein by reference in its entirety, how in-situ regenerable granular sorbents can be formed into cartridges and assemblies for treating indoor air. Thus, according to some embodiments of the present disclosure, granular sorbents may be combined with carbon cloth filters into a cartridge that contains both, and thus, may be capable of removing a larger number of contaminants, for example CO 2  and VOCs, which together represent the most common indoor gas contaminants. 
         [0046]    In some embodiments, the removal of CO 2  from the air is achieved by a sorbent based on solid supported amines, as was described, for example, in applicant&#39;s PCT application PCT/US12/038343, which is incorporated herein by reference in its entirety. 
         [0047]      FIGS. 2A-2C  each illustrates some embodiments of a sorbent cartridge  200  including a VOC filtration cartridge that comprises solid sorbent  210  as well as a layer of carbon fiber cloth  108 . Air flowing through the cartridge  200  may come into contact first with the solid sorbent  210  and then with the carbon fiber cloth  108 , thereby being at least in part cleansed of the gas species that are captured by the solid sorbent  210  and subsequently flowing to the carbon fiber cloth  108 . Alternatively, the air flowing through the cartridge  200  may come into contact first with the carbon fiber cloth  108 . 
         [0048]    In some embodiments, the carbon fiber cloth  108  lines an interior of mesh  112  of the cartridge  200  that holds the solid sorbent  210 . The sorbent cartridge  200  may further include, according to some embodiments, permeable material  116 , and the enclosure  130 . The combination of the carbon fiber cloth  108  and the solid sorbent  210  in the same cartridge  200 , as seen in  FIG. 2A , presents a simplified deployment of the solution, i.e., contaminant removal from air, and determines that adsorption and regeneration of the two materials will be concurrent (according to some embodiments). 
         [0049]    As described above, in some embodiments, several layers of flat carbon fiber cloths  108  may be positioned in parallel, and in the same cartridge  200 , as shown in  FIG. 2B . The sorbent cartridge  200  may also comprise an additional sorbent  216  for removal of other contaminants and may be formed in any suitable configuration. The additional sorbent  216  may be formed as a layer or slab and a single or plurality of layers may be provided, as shown in  FIG. 2B . 
         [0050]    In  FIG. 2C , a plurality of sorbent cartridges  200  may be provided and arranged in a V-bank arrangement or any other suitable arrangement, according to some embodiments. In  FIG. 2C , the sorbent cartridges  200  may be configured as shown in  FIG. 2A , though the sorbent cartridges  200  may be configured as shown in  FIG. 2B . 
         [0051]    In  FIG. 3 , a plurality of sorbent cartridges  240  may be provided and arranged in a V-bank arrangement, for example, according to some embodiments. In such embodiments, the sorbent cartridges  240  may comprise the granular sorbent  210  and the carbon fiber cloth  108  may be provided in a substantially perpendicular orientation in respect to the plurality of sorbent cartridges  240 . The carbon fiber cloth  108  may be provided upstream, i.e., before the sorbent cartridges  240 . Alternatively, the carbon fiber cloth  108  may be provided downstream, i.e., after the sorbent cartridges  240 , as shown in  FIG. 3 . In  FIG. 3  the carbon fiber cloth  108  is shown pleated, though a flat carbon fiber cloth  108  may be provided, or one with surface topography that, for example, increases surface area. Additionally, a plurality of carbon fiber cloths  108  may be provided (according to some embodiments). 
         [0052]    The cartridges  200  shown in  FIGS. 2A-2C  and cartridges  240  of  FIG. 3 , may be configured for removable insertion into the air treatment assembly  100 , such as via access door  190 . 
         [0053]    In some embodiments, the air treatment assembly  100  may be operated with the help of control system  250  which may comprise an automated electromechanical control unit that determines at what time or period to open or close one or more of dampers  154  and  158 , for example, when to activate one or more fans  159  and  180 , responsible for flowing air through the air treatment assembly  100 , for example, when to activate a heating (or cooling) component, that is configured to heat the purge gas  160 , and also when to signal for a service call if necessary, for example. 
         [0054]    The control system  250  may comprise a processor having computer instructions operating thereon for controlling one or more of the dampers, fans and heaters/conditioners associated with the air treatment assembly  100 . The instructions may comprise instructions operating the adsorption mode (i.e. the indoor mode of operation) and the regeneration mode. 
         [0055]    To assure the air quality as well as the performance and benefits of the VOC removal system, in some embodiments, detection and/or monitoring functionality for detecting and/or monitoring of VOC levels in the air is provided. An air treatment monitoring system, for monitoring an air treatment assembly for reducing VOCs contained in indoor air, may comprise one or more sensors  260  configured to monitor concentration of VOCs in the air stream, wherein one or more electronic signals from the sensors  260  are transmitted to the monitoring system and comprise at least one of inputs for the control system to determine if the air treatment assembly  100  needs to be regenerated, serviced or turned off or on, data for recording and/or monitoring air quality, and data for recording the performance of the air treatment assembly  100 . 
         [0056]    The sensors  260  and/or systems are capable of measuring concentrations of specific VOC species and/or total VOC concentration and can be installed upstream and/or downstream from the VOC removal system, and/or in other suitable locations in the building or the enclosed environment. The measurements can be electronically transmitted, by wireline or wireless signals, to the control system that monitors, records and controls the operation of the VOC removal assembly, or simply to a recording unit to collect and save the measured data. 
         [0057]    Sensing of the VOC concentrations can be done in any number of ways. In some embodiments, a photoionization detector unit may be provided to measure total VOCs. In some embodiments, a differential mobility spectrometer can be provided to detect specific species of contaminants. In some embodiments, metal-oxide VOC sensors can also be used, as can infrared spectrometers. In some embodiments, any other suitable sensor that is sensitive to the target VOC species can be used for this purpose. 
         [0058]    Although a few variations have been described in detail above, other modifications are possible. For example, any logic flows depicted in the accompanying figures and described herein does not require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of at least some of the following exemplary claims. 
         [0059]    Example embodiments of the devices, systems and methods have been described herein. As may be noted elsewhere, these embodiments have been described for illustrative purposes only and are not limiting. Other embodiments are possible and are covered by the disclosure, which will be apparent from the teachings contained herein. Thus, the breadth and scope of the disclosure should not be limited by any of the above-described embodiments but should be defined only in accordance with claims supported by the present disclosure and their equivalents. Moreover, embodiments of the subject disclosure may include methods, systems and devices which may further include any and all elements from any other disclosed methods, systems, and devices, including any and all elements corresponding to translocation control. In other words, elements from one or another disclosed embodiments may be interchangeable with elements from other disclosed embodiments. In addition, one or more features/elements of disclosed embodiments may be removed and still result in patentable subject matter (and thus, resulting in yet more embodiments of the subject disclosure).