Abstract:
A device for exposure of a fluid to radiation comprising a tube ( 20 ) through which a fluid is caused to flow , a plurality of radiation sources ( 14 ), and a plurality of reflectors ( 48 ) to cause the radiation to be focused on the fluid.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/441,930, filed on Jan. 21, 2003, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to liquid disinfection and, more particularly, to liquid disinfection using ultraviolet (UV) radiation. 
         [0003]    It is known to use UV radiation to disinfect clear or opaque liquids such as water, including wastewater, juices, brines, marinades, beverages, and the like. A couple of examples include U.S. Patent Nos. 3,527,940 and 4,968,891, the disclosures of which are incorporated herein by reference. Using UV radiation to disinfect liquids offers many advantages that often make it a very attractive option as compared to other methods of disinfecting liquids. It will often provide for improved disinfection in a fast, simple, relatively inexpensive manner. 
         [0004]    Still, prior equipment and methods of disinfecting liquids using UV radiation suffer from a number of disadvantages. For example, the relatively fragile nature of the equipment has placed undesirable limitations on the flow rates that may be treated and operating pressures that may be used. The relatively fragile nature of the equipment similarly limited pressures and flow rates that could be used for cleaning purposes, making it more difficult or impossible to provide the convenience of clean in place equipment. The effectiveness of UV radiation to disinfect a liquid diminishes rapidly, likely exponentially, with distance, so relying primarily upon turbulence in a liquid to provide for even, thorough disinfection of the liquid can be unreliable. Also, exposure times for desired levels of disinfection can often lead to the use of undesirably large equipment or the use of an undesirably large number of units of such equipment, adding to the cost of the system and taking up valuable floor space. In a typical prior art unit, a significant portion of the radiation emitted by the bulbs is not directed toward the liquid to be treated and is wasted, making inefficient use of the radiation and of the power consumed to generate the radiation. Prior cabinets or units used to provide UV disinfection of liquids also provided little or no flexibility in handling differing flow patterns, flow rates, and treatment times. Further, prior cabinets and units were difficult and time-consuming to service or repair, and typically required an entire cabinet or unit to be shut down and placed out of service for extended periods. 
       SUMMARY OF THE INVENTION 
       [0005]    It is therefore an object of the present invention to provide a system and method for treating a liquid with radiation that offers increased efficiency. 
         [0006]    It is a further object of the present invention to provide a system of the above type that allows the flexibility of switching between parallel and series flow with minimal adjustments. 
         [0007]    It is a still further object of the present invention to provide a system of the above type that provides a rugged system that may handle high pressures and flow rates. 
         [0008]    It is a still further object of the present invention to provide a system of the above type which uses modular illumination units to allow for fast and easy replacement of bulbs or other components. 
         [0009]    It is a still further object of the present invention to provide a system of the above type that makes highly efficient use of radiation generated by treating bulbs. 
         [0010]    It is a still further object of the present invention to provide a system of the above type which provides for an extended treatment path without a corresponding increase in the length of the treatment chamber. 
         [0011]    It is a still further object of the present invention to provide a system of the above type which provides for more even and thorough exposure of the liquid to be treated. 
         [0012]    It is a still further object of the present invention to provide a system of the above type which provides for the convenience of fluid input and output at the same end of a treatment chamber. 
         [0013]    Toward the fulfillment of these and other objects and advantages, a radiation treatment method and device are disclosed. The device comprises a treatment chamber and a radiation source, such as one or more UV bulbs, disposed in close proximity thereto. The treatment chamber has a header to which are connected coaxially aligned inner and outer tubes. The coaxially aligned tubes form an annulus area, and a static mixer defines a spiral liquid travel path through the annulus. An exit path is provided through the center of the inner tube and through the header. Input and output manifolds are provided, and adjacent treatment chambers may alternately be aligned and connected to provide for parallel or serial flow. Modular illumination units may be used in which two mirror image halves each have a bracket that supports and aligns reflectors and UV bulbs adjacent each treatment chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0014]    The above brief description, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of the presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein: 
           [0015]      FIG. 1  is a sectional, side elevation view of a treatment chamber forming part of a radiation treatment device of the present invention; 
           [0016]      FIG. 2  is a sectional, overhead view of a radiation treatment device of the present invention; 
           [0017]      FIG. 3  is a partial, side elevation view of an alternate embodiment of a radiation treatment device of the present invention; 
           [0018]      FIG. 4  is a is a partial, sectional, overhead view of an alternate embodiment of a radiation treatment device of the present invention; 
           [0019]      FIG. 5  is an overhead, perspective view of a parallel flow alignment of a radiation treatment device of the present invention; 
           [0020]      FIG. 6  is an overhead, perspective view of a series flow alignment of a radiation treatment device of the present invention; 
           [0021]      FIG. 7  is a front elevation view of a cabinet for housing a radiation treatment device of the present invention; and 
           [0022]      FIG. 8  is a partial, side elevation view of a cabinet for housing a radiation treatment device of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Referring to  FIG. 1 , the reference numeral  10  refers in general to a radiation treatment device of the above invention. The device  10  comprises a treatment chamber  12  and a radiation source  14  disposed in close proximity thereto. 
         [0024]    The treatment chamber  12  comprises a header  16 , inner and outer tubes  18  and  20 , a static mixer  22 , and an end cap  24 . The header  16  has an outer housing  26 , an inner header tube  28 , an input pipe  30  with an input opening  32 , and an output pipe  34  with an output opening  36 . The outer housing  26  is open at the top, closed at the bottom, and has two side openings disposed on opposite sides, with one side opening being larger than the other. A mount  38  is secured to the bottom wall of the outer housing  26 . The input pipe is affixed to the outer housing  26 , aligned with the larger of the two side openings. The output pipe  34  is affixed to the outer housing  26  aligned with the smaller of the two other side openings. The input and output pipes  30  and  34  both have inner diameters of approximately 1.5 inches. The inner diameter of the output pipe  34  is larger than the diameter of the side opening. The inner header tube  28  has an input opening centrally disposed and coaxially aligned with the outer housing  26  and an output opening aligned with the smaller of the two side openings. The inner diameter of the inner header tube  28  is substantially the same as the diameter of this side opening. The header  16  is preferably made of stainless steel and is of clean in place construction. It is of course understood that the header  16  may be made of any number of different materials or combinations of materials. It is also understood that the header  16  may be assembled or fabricated from a number of different parts or may be cast or molded as one or more integral pieces. 
         [0025]    Outer tube  20  is made of a material that is transparent to UV radiation or to the type of radiation used. The outer tube  20  is preferably constructed of a polymer, is more preferably constructed of a fluoropolymer, and is most preferably constructed of fluorinated ethylene propylene. The outer tube may of course be constructed of any number of materials known to possess the desired degree of transparency. The outer tube  20  has a length of approximately 60 inches and has an inner diameter of approximately 1.25 inches. A lower portion of the outer tube  20  is secured to the header  16 , such as by using a hose clamp  40 . The end cap  24  is affixed to an upper portion of the outer tube  20 , such as by using a hose clamp  40 . A lower surface  42  of the end cap  24  is curved to assist in redirection of the liquid with minimal pressure drop. The cap  24  is preferably stainless steel. 
         [0026]    An output end of the inner tube  18  is affixed to the input end of the inner header tube  28 , and the inner tube  18  extends coaxially aligned within the outer tube  20  along most if not all of the height of the outer tube  20 . The inner tube  18  is preferably stainless steel having an inner diameter of substantially within a range of from approximately 0.5 inch to approximately 3.25 inch. The inner tube has an outer diameter that is substantially within a range of approximately from approximately 0.75 inch to approximately 3.5 inch. The outer diameter of the inner tube  18  and the inner diameter of the outer tube  20  are preferably selected to provide a relatively narrow annulus  44  between the two having a width of approximately 0.25 inch. An inner surface of the inner tube  18  defines an inner flow path. An inner surface of outer tube  20  and an outer surface of inner tube  18  define an outer flow path. An opening in a distal end of the inner tube  18  places the outer flow path in fluid flow communication with the inner flow path. The outer surface of the inner tube  18  is not transparent with respect to the radiation from the radiation source  14  and is preferably reflective of the radiation. 
         [0027]    The static mixer or helical member  22  is an auger style static mixer that is affixed to the outer diameter of the inner tube  18 , such as by welding. The mixer  22  extends between the outer wall of the inner tube  18  and the inner wall of the outer tube  20  and preferably contacts the inner wall of the outer tube  20 . The mixer  22  is preferably stainless steel. Different degrees of winding may be used depending upon desired characteristics of the device  10 . In one preferred embodiment the winding provides a liquid travel path of approximately 3.9 inches for each 1 inch of annulus  44  height. For a treatment chamber  12  in which the height of the annulus  44  area is approximately 60 inches, this would provide a liquid travel path of approximately 234 inches. 
         [0028]    Referring to  FIG. 2 , a modular illumination unit  46  is provided, formed from two mirror image sections  47 . The sections  47  are connected to one another by a hinge  49  or in any conventional manner. Each section  47  comprises a plurality of bulbs  14 , one or more reflectors  48 , and a bracket  50 . The bracket  50  supports and aligns the bulbs  14  and supports and aligns the reflector or reflectors  48  positioned adjacent to the bulbs  14 . The reflector  48  is configured with a curved portion or segment, such as a semi-circular, hyperbolic, or parabolic shaped portion or segment, associated with each bulb  14 , disposed and aligned to reflect and focus radiation emitted from outer portions of the bulb  14  back toward the treatment chamber  12 . The segments are disposed so that the reflector  48  is generally clamshell shaped. In that regard, a cross section of one segment falling in a common plane of a cross section of an adjoining segment does not form a portion of a common circle or semi-circle with the cross section of the adjoining segment. Each cross section is preferably semi-circular, and each cross section of a segment has an arc length that is greater than approximately 45°. The inner surface of the reflector  48  is selected to be highly reflective of the radiation used. For example, if a UV bulb  14  is used, the inner surface is preferably polished aluminum. Each section  47  is secured to its mating section  47  and is secured within the cabinet  66  in any number of ways, such as being secured to a back wall of the cabinet or to brackets disposed within the cabinet  66 . In the preferred embodiment, one section  47  is disposed toward a back portion of the cabinet  66 , and a mating section  47  is disposed toward a front portion of the cabinet  66  so that the front section  47  may be easily opened to provide access to the treatment chamber  12  and to the sections  47  of the illumination unit  46 . Each section  47  is independently removable without the need to remove an associated treatment chamber or mated section  47 . The brackets  50  of each section  47  are disposed to place the bulbs  14  in very close proximity to the outer surface of the outer tube  20 . In the preferred embodiment, in which the modular concept is used, a separate modular illumination unit  46  is associated with each treatment chamber  12 . It is also preferred to provide an extra or spare modular illumination unit  46  along with the device  10 . This will reduce down time by making it easy to quickly replace an installed unit  46  with a spare unit  46  if the installed unit is in need of repair, maintenance, or replacement. 
         [0029]    In an alternate embodiment depicted in  FIGS. 3 and 4 , one or more bulb racks  52  may be used to support and align a plurality of outer tubes  20  of a plurality of treatment chambers  12 , along with the bulbs  14  and reflectors  48  to be used with each treatment device  10 . As seen in  FIG. 3 , sets of holes or openings  54  and  56  are provided to support and align the outer tubes  20  and bulbs  14 , respectively. 
         [0030]    Referring to  FIG. 5 , input and output manifolds  58  and  60  are provided and are disposed to allow for parallel flow of a liquid through a plurality of adjacent treatment chambers  12 . The manifolds are provided in a modular arrangement with a first set of associated input and output manifold segments  58   a  and  60   a , a second set of associated input and output manifold segments  58   b  and  60   b , and so on for the desired number of treatment chambers  12  to be used. The length  62  of the each input and output manifold  58 ,  60  segment is equal to the distance  64  between the input opening  32  of the input pipe  30  and the output opening  36  of the output pipe  34 . This allows each treatment chamber  12  to be quickly and easily adjusted to provide for either parallel flow as seen in  FIG. 5  or to provide for series flow as seen in  FIG. 6 . 
         [0031]      FIG. 6  shows a plurality of treatment chambers  12  arranged to provide for series flow through a plurality of treatment chambers  12 . In this arrangement, the output opening  36  of an output pipe  34  of a first treatment chamber  12  is aligned with an input opening  32  of an input pipe  30  of a second treatment chamber  12 , and so on for the desired number of treatment chambers  12 . 
         [0032]    As shown in  FIG. 7 , a radiation treatment device  10  of the present invention may also include a cabinet  66  and related components. One or more treatment chambers  12  and sets of associated bulbs  14 , reflectors  48 , and input and output manifolds  58 ,  60  are housed within the cabinet  66 . The cabinet  66  is preferably made primarily of stainless steel. Other components may be disposed within or positioned near the cabinet  66 . For example, a power line  68  may supply power to controls  70  and to ballast  72  associated with each bulb  14 , which may be housed in the cabinet  66  or separately above the cabinet  66 . A fan  74  may be provided for cooling the ballast  72  and controls  70 , and drain pipes  78  may be provided in the cabinet  66  floor. In the preferred embodiment, a separate fan  74  will be associated each modular illumination unit  46 , with the fan  74  disposed to provide a positive pressure cabinet. It is of course understood that any number of different fan  74  arrangements may be used and that one or more fans may be disposed to provide either a positive pressure cabinet or a negative pressure cabinet. One or more input or output pipes  80 ,  82 , and  84  may be provided, disposed in lower side walls of the cabinet  66 . As best seen in  FIG. 8 , outer pipes  80  and  82  are disposed to align with input and output manifolds  58  and  60 , respectively, to provide a path for parallel flow of liquid through the treatment chambers  12  such as when the treatment chambers  12  are aligned as depicted in  FIG. 5  . The centrally located pipes  84  are disposed to align with input and output pipes  30  and  34  of the treatment chambers  12  when the treatment chambers  12  are aligned for series flow, such as seen in  FIG. 6 . 
         [0033]    Referring to  FIGS. 5 and 6 , in operation, a plurality of treatment chambers  12  are aligned as desired to provide for parallel or series flow through the desired number of treatment chambers  12 . It is of course understood that a single treatment chamber  12  may also be used if desired. Once the treatment chambers  12  are aligned as desired and the cabinet doors  86  closed for added protection against exposure to UV radiation, the bulbs  14  are activated to provide UV radiation. The liquid to be treated is then provided to the device  10  at the desired pressure and flow rate. It is understood that the device  10  may be used in connection with most any liquid, including but not limited to clear or opaque liquids such as water, including wastewater, juices, brines, marinades, beverages, and the like. 
         [0034]    In parallel flow ( FIG. 5 ) the liquid will pass through and fill the desired number of input manifold segments  58   a ,  58   b ,  58   c  and will pass from each input manifold  58  segment into an associated treatment chamber  12 . As best seen in  FIG. 1 , the liquid passes through the input pipe  30 , through the housing  26 , and into the annulus  44  between the inner tube  18  and outer tube  20 . The static mixer  22  routes the liquid in a tight spiral pattern along a helical path upward through the annulus  44  to an upper portion of the treatment chamber  12 . As the liquid passes through the narrow annulus  44  in close proximity to the bulbs  14 , UV radiation from the bulbs  14  provides the desired degree of disinfection. The use of the auger style static mixer  22  provides for significant mixing and churning of the liquid as it passes upward through the annulus  44  so that different portions of the liquid are constantly being moved closer to and further from the bulbs  14 . This ensures thorough and even radiation exposure throughout the liquid and greatly reduces the chances of leaving isolated portions relatively untreated or significantly over-treated. The end cap  24  arrests upward flow of the liquid and redirects the liquid to flow downward through the inner tube  18 . The liquid then passes through the inner tube  18 , through the inner header tube  28 , and through the output pipe  34 . If the treatment chamber  12  is aligned to provide for parallel flow ( FIG. 5 ), the liquid passes from the output pipe  34  to and through the associated output manifold  60  segment for further use or treatment. If the treatment chamber  12  is aligned to provide for series flow ( FIG. 6 ), the liquid passes from the output pipe  34  of one treatment chamber  12  to the input pipe  30  of another treatment chamber  12  to repeat the process described above. 
         [0035]    The rugged device  10  of the present invention may be operated under wide ranges or pressures and flow rates without fear of damaging the device  10 . For example, the device  10  of the present invention may be safely operated at a working pressure reaching or exceeding a pressure that is preferably substantially within a range of from approximately 30 psig to approximately 60 psig and that is more preferably approximately 57 psig. The device  10  may withstand burst pressures reaching or exceeding a pressure that is preferably substantially within a range of from approximately 100 psig to approximately 300 psig and that is more preferably approximately 286 psig. Desired flow rates for many applications will typically be within a range of from approximately 1 gallon per minute to approximately 20 gallons per minute. Similarly, desired flow rates for typical clean in place cleaning will typically be less than or equal to approximately 25 gallons per minute. Still, much higher flow rates may be desirable for some applications, such as for the batch processing of juice. In the batch processing of juice, it is sometimes desirable to process flow rates reaching or exceeding approximately 70 gallons per minute. Because of limitations imposed by the relatively fragile nature of prior radiation treatment devices, it is not believed that UV radiation treatment has been used in applications calling for such high flow rates. In contrast, the rigid construction of the present invention will preferably allow the present invention to safely process flows rates of up to approximately 30 gallons per minute, will more preferably allow the present invention to safely process flows rates of up to approximately 55 gallons per minute, and will most preferably allow the present invention to safely process flows rates of up to approximately 80 gallons per minute. A treatment chamber  12  typically processes approximately 10 to 12 gallons per minute. Parallel flow is typically used for higher rates. 
         [0036]    Other modifications, changes and substitutions are intended in the foregoing, and in some instances, some features of the invention will be employed without a corresponding use of other features. For example, any number of treatment chambers  12  may be used, from one to several. Similarly, although it is preferred to use a configuration of eight bulbs  14  per treatment chamber  12 , any number of bulbs  14  may be used in connection with a treatment chamber  12 , from one to several. Also, any number of different types of mixers  22  may be used in the annulus  44 , or a mixer  22  may be omitted. Further, any number of different flow paths may be used, including but not limited to a flow path that is roughly the reverse of that described in the preferred embodiment. Similarly, strictly series flow may be used, strictly parallel flow may be used, or any number of combinations of series and parallel flows may be used. Also, the header  16  may be disposed in different locations, such as at the top of the treatment chamber  12 . Similarly, any number of different methods may be used to route the fluid to or from the annulus  44  area and to or from the inner tube  18 . Although bulbs  14  providing UV radiation are preferred, any number of different types of radiation and types of radiation sources  14  may be used depending upon the desired application. Further, the reflectors  48  may take any number of shapes, sizes or configurations or may be omitted. Further still, any number of different structures and arrangements may be used for supporting and aligning the various components of the device. Similarly, any number of different structures and arrangements may be provided for shielding users and surrounding environments from radiation exposure. Although the preferred embodiment is particularly useful for treating liquids, it is of course understood that the invention may be used in connection with treating any number of different forms of matter. For example, a device of the present invention may also be used to treat a gas or to treat fluid matter, including but not limited to solid particulate matter. It is of course understood that all quantitative information is given by way of example only and is not intended to limit the scope of the present invention.