Abstract:
A sterilizer apparatus for treating liquids, especially opaque and turbid ones characterized by a low UV radiation penetration depth, utilizing a novel in-line mixer designed inside an elongated reactor chamber built around an ultraviolet lamp. Other applications and adaptations of the presently disclosed apparatus include mixing fluids as part of various industrial processes.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to UV disinfection systems. More specifically, but not by way of limitation, this disclosure relates to treating opaque liquids using a novel in-line mixer designed to maximize the liquid exposure time to UV radiation, while mixing the liquid to assure whole liquid volume treatment. Furthermore, the present disclosure relates to fluids mixing technologies. 
       CROSS REFERENCE TO RELATED APPLICATIONS 
       [0002]    U.S. Patent Documents
   U.S. Pat. No. 5,393,419—Ultraviolet Lamp Assembly for Water Purification (February 1995)   U.S. Pat. No. 5,626,768—Sterilization of Opaque Liquids with Ultraviolet Radiation (May 1997)   U.S. Pat. No. 5,675,153—UV Apparatus for Fluid Treatment (October 1997)   U.S. Pat. No. 5,785,845—Water Purifying System (July 1998)   U.S. Pat. No. 6,280,615 B1—Fluid Mixer and Water Oxygenator Incorporating Same (September 2001)   U.S. Pat. No. 6,344,176 B1—Device for Treating Liquids, Especially Coolants and Lubricants (February 2002)   U.S. Pat. No. 6,916,452 B1—Sterilization of Liquids Using Ultraviolet Light (July 2005)   
 
         [0010]    U.S. Patent Applications
   2013/0313105 A1—Method and Device for Treating Opaque Fluids with UV Radiation (November 2013)   
 
       BACKGROUND OF THE INVENTION 
       [0012]    In an Ultra Violet (UV) reactor without any or adequate fluid control devices, i.e. a simple or plain chamber with UV source(s), the fluid takes the shortest path in its passage through the reactor between the inlet and outlet piping (see  FIG. 1 ). Laminar flow based reactors require fluids with high transmission levels (low UV absorbance properties) to effect adequate dose levels on the fluid since the fluid in the region of the wall of the reactor (farthest away from the lamp or lamps) will receive the lowest dose from the UV source(s). The lower the transmission of the fluid (i.e. the higher the absorbance properties with respect to the UV wavelength), the lower the UV levels will be at the reactor wall, and with laminar (or short circuit) flow, the higher the biological reactor level breakthrough will be (i.e. higher levels of pathogens passing through the reactor untreated by the UV). From  FIG. 1  it can be seen that the fluid on the opposite side of the inlet and outlet sections (A) are effectively stagnant (zero to no flow) and merely are a void of fluid when the reactor is initially filled with fluid—all (or most) of the fluid flow occurs between the inlet and outlet piping. Laminar flow based reactors have the advantage of lower head pressure requirements to drive fluid through them, but suffer from a small range of transmission level variance that they can effectively cope with or treat (i.e. suited to high water quality only). Laminar flow between the inlet and outlet of a reactor is therefore highly undesirable when the intent is to biologically treat fluids with a large range of transmission levels, and fluids with low or even very low UV transmission levels (UVT), approaching or down to 0% UVT. 
         [0013]    Typical applications for low UVT fluids disinfection by UV radiation are found in copper forming industry an oil-water emulsion is used to cool and lubricate the copper forming process as it passes through the extrusion mold. The emulsion after forming is fed through a filter to remove any metallic debris. After the filter, the heated emulsion is fed though a heat exchanger to reduce the temperature and recycled back to the extrusion process. After the emulsion exits the heat exchanger and returns the extrusion mold its temperature is typically around 110° F. (43.3° C.), at this temperature bacteria and pathogens are able to consume the oil as nutrient. Microbial contamination of Metal Working Fluids (MWFs) causes biofouling and degradation and is also associated with several health hazards. Development of an effective control method is therefore essential to reduce microbial loading in MWFs. In order to demonstrate the harmful pathogenic potential to humans, some biological background of the species is necessary. Bacteria,  Pseudomonas fluorescens, P. oleovorans  subsp.  lubricantis  and  Mycobacterium chelonae  are found in the MWF&#39;s ( Pseudomonas  species).  Stenotrophomonas maltophilia  is an emerging multidrug-resistant global opportunistic pathogen found in the MWF&#39;s. The increasing incidence of nosocomial and community-acquired  S. maltophilia  infections is of particular concern for immunocompromised individuals, as this bacterial pathogen is associated with a significant fatality/case ratio.  S. maltophilia  is an environmental bacterium found in aqueous habitats, including plant rhizospheres, animals, foods, and water sources. Infections of  S. maltophilia  can occur in a range of organs and tissues; the organism is commonly found in respiratory tract infections.  S. maltophilia  has been reported to survive and persist in chlorinated water distribution systems. Treating the bacteria in the MWF&#39;s with chemicals (biocides) poses tremendous health issues to the factory workers, making them ill and affecting production; not using biocides allows the pathogens to consume the oil in the MWF&#39;s which negatively affects the forming process and exposes the workers to a pathogen bio-hazard. The solution is to treat the pathogens with a non-chemical process such as UV radiation which protects both the oil in the MWF&#39;s and the factory personnel, however the UVT values of the MWF&#39;s can be as low as zero %; for this application a reactor with a high fluid mixing ratio, along with high levels of turbulence is required to effectively channel all the fluid within the reactor to the UV source as often, and for as long as possible. To achieve this objective the in-line mixer in this publication will be used. 
         [0014]    Fruit juice and liquid dairy products requires sterilization after production and prior to the packaging process (bottles, cartons etc); this can be achieved by an electron beam irradiating process which is a costly piece of equipment, or alternatively with a UV reactor with an in-line mixer. 
         [0015]    In the off-shore marine oil extraction process, sea water is often driven into the well to displace the oil; however this water requires disinfection otherwise the bio-loading of the sea water will consume the oil as nutrient. A UV reactor with an in-line mixer will ensure maximum UV dose to the sea water with a range of UVT properties prior to the introduction into the well site. 
         [0016]    Existing prior art apparatuses recognize the benefits of creating turbulences in the fluid under treatment with the purpose of thoroughly mixing it to assure that all the volume of the fluid under treatment will be submitted to UV radiation and to eliminate stagnant zones where the microorganisms are able to multiply while avoiding exposure to UV radiation. One invention (U.S. Pat. No. 5,626,768) proposes as method of creating turbulences to increase the fluid velocity, failing to realize that radiating the whole fluid is only part of the disinfection process. As important is the time of exposure to UV radiation that needs to be long enough in order for the fluid under treatment to get the necessary dose of energy to deactivate the microorganisms&#39; DNA. Since UV radiation energy is proportional with both radiation intensity and exposure time, when increasing the fluid velocity, the exposure time decreases, with its undesirable consequences. 
         [0017]    Other existing inventions are using devices meant to create fluid turbulences, which upon careful examination do not deliver the claimed results. U.S. Pat. No. 5,675,153 includes a UV disinfection reactor which has a cylindrical shape and an internal helical deflector having also radial slots. Liquid flow simulation studies on this apparatus shows that the claim is actually overstated. There is indeed some swirling effect which will result in turbulences, but it can be easily demonstrated using modern liquid flow simulation software that the ECO-UV invention is superior for opaque liquid treatment using UV radiation technology. Besides, ECO-UV&#39;s solution is much simpler and cheaper to manufacture. Same conclusion applies to U.S. Pat. No. 5,785,845 which develops an elaborate and complex internal profile of grooves and ridges to create a baffling structure that will alternate rings-like with spiral-like paths in the contaminated liquid&#39;s way throughout an elongated reactor, or U.S. Pat. No. 6,280,615 B1 which develops an elaborate and complex internal profile of scallop shapes having peaks and troughs, with the peaks of the two surfaces being relatively offset so as to cause the liquid and the gas entering the chamber to flow along a generally sinuous path through the chamber to create a turbulent flow which promotes intimate mixing. Although the swirling effect will cause the fluid to spend additional time in the treatment zone, the turbulences created by this solution were found to have questionable efficiency. 
         [0018]    Another invention (U.S. Pat. No. 6,344,176 B1) adopts a different approach in order to assure whole liquid volume exposure to UV radiation. It creates a thin film of the treated fluid by a partially immersing a rotating drum structure that will transport the. fluid through an area with powerful UV radiation. The shortcomings associated with this invention are that it will need a large surface structure to efficiently treat enough fluid flow, since it is able to move just a thin layer into the treatment zone. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  represents a typical UV Reactor used for biological sterilization of a liquid using UV radiation. 
           [0020]      FIG. 2  illustrates the in-line mixer detail that constitutes the object of the present invention, including the plates designed to create the liquid flow turbulences and their support rods. 
           [0021]      FIG. 3  is a two-dimensional illustration of the in-line mixer design that constitutes the object of the present invention emphasizing the turbulence enhancing plates orientation, in-line mixer turbulence zones and the in-line mixer end plates. 
           [0022]      FIG. 4  represents the complete UV Reactor incorporating the in-line mixer which is the object of this invention. Suggested liquid flow patterns are graphically represented to highlight the benefits claimed by this invention. 
           [0023]      FIG. 5  represents the complete fluid mixing apparatus for various industrial processes which is another object of this invention. Suggested fluid flow patterns are graphically represented to highlight further benefits claimed by this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Certain aspects and features of the present disclosure relate to a UV sterilization apparatus including an in-line mixer to enhance the disinfection process and make it efficient when treating turbid and opaque fluids (Low UVT % and high UV absorbance). The in-line mixer ( FIG. 2 ) is comprised of a series of plates held together by means of a support system (typically multiple rods). In this disclosure each individual plate has a “horseshoe” type appearance, the top or round section (A) practically and purposely closes off the pipe-like section of the reactor where it is positioned into fluid flow. The lower section (C) of the plate is open to allow the fluid to pass freely. The individual plate has small openings (B) on the circumference where the plate arc and reactor inner wall mate to allow small amounts of fluid to pass. It also has an inner plate arc (D) to allow the UV source to pass in the proximity of typically the quartz sleeve which houses the UV lamp. The inner plate arc (D) is larger than that of the quartz sleeve allowing a small volume of fluid to pass between the quartz sleeve and the in-line mixer plate at the said location (D). 
         [0025]    In some examples in  FIG. 3 , each plate has 3 securing holes, however there are 4 supporting rods in the assembly; each in-line mixer plate is attached by three of the four rods allowing the forth rod to pass through the opening of the plate (C in  FIG. 2 ) in each case. Following the first plate in the assembly (Zone 1), each sequential in-line mixer plate is rotated 90 degrees in succession (Zones 2 through 9 in this configuration). The plate openings along the assembly follow the 2D Cartesian coordinate plane of 270 degrees for zone 1, 0 degree for zone 2, 90 degrees for zone 3, 180 degrees for zone 4 and repeating thereafter for as many partial rotations that are required for the particular application. For the in-line mixer design, a minimum of one plate is required. One plate will interrupt the short-circuiting laminar fluid flow effect between the inlet and outlet reactor or general piping as long as the in-line mixer plate opening (C in  FIG. 2 ) is located on the opposite end of the said reactor piping. Any number of plates can be used for a particular application; in this example two complete fluid rotations are achieved with eight plates. In this example fluid is introduced into zone 1 and exits at zone 9. For the minimum configuration using one plate, fluid would be introduced into zone 1 and exit at zone 2; there would be no zones beyond zone 2 in the minimum configuration. A typical in-line mixer design has, but is not limited to, two end plates to complete the assembly and is the start and finish of the support rod mechanism. The end plates typically have a locking screw type mechanism to lock the assembly to the reactor walls or pipe (application dependant); the locking screws serve to secure the in-line mixer inside the vessel in which it is installed such that the passing fluid around the in-line mixer assembly does not cause it to rotate. 
         [0026]    In some examples ( FIG. 4 ) the fundamental fluid flow (A) is forced through the in-line mixer openings (C in  FIG. 2 ). Since each of the plates is rotated 90 degrees (from  FIG. 3 ), the fundamental fluid flow rotates as it passes from the inlet to the outlet sections. Since there is a small gap between the inner arc of the in-line mixer plate(s) and the outer diameter of the quartz sleeve, a relatively small volume of fluid passes between the plate and the quartz sleeve (B) at a high velocity with respect to the fundamental fluid flow (A). Fluid flow (B) is a mechanically forced thin film and passes directly over the quartz sleeve and is exposed to the maximum radiant flux of the UV source, after passing the in-line mixer plate Fluid (B) joins the fundamental fluid path (A) until the next plate in the in-line mixer assembly is encountered by the flow where after the process repeats itself. Relatively small amounts of fluid (C) located at the reactor extremities (location farthest from the UV source), flow through the openings located at the upper arc of the turbulator plate (B in  FIG. 2 ) and join the fundamental fluid flow (A). The fluid flow through these openings rotate with the fundamental flow though the alternating openings of the in-line mixer plates to alleviate reactor wall extremity fluid dead zones (areas with stagnant or no fluid flow). The effects of fluid flows (A), (B) and (C) create effective mixing of all the fluid within the reactor or vessel, break up otherwise stagnant fluid regions and eliminate inlet to outlet fluid short circuiting. UV dose of the fluid inside a reactor is defined as the product of UV intensity (radiant flux) and residence time spent therein; from this definition the biological effectiveness of a UV reactor would therefore be dependant on the aggregate or average delivered dose throughout the fluid, i.e. fluid passing directly over the UV source would receive the maximum radiant flux, while the fluid passing at the reactor walls would receive the minimum radiant flux. In a reactor without an in-line mixer, fluids with high transmission properties would receive adequate UV intensity levels at the reactor walls making the aggregate dose throughout the reactor biologically effective, while fluids with low transmission properties would have low or inadequate radiant flux at the reactor wall location allowing a volume of untreated fluid to bypass the reactor; the aggregate of the untreated fluid combined with the treated fluid that did receive an adequate dose (close to the UV source) could render the reactor biologically ineffective depending on how low the UVT properties were (regardless of the flow rate). In a reactor with an in-line mixer where all of the fluid is forced into a close proximity of the UV source, albeit for short periods of time, but repetitive; the radiant flux and residence time distribution in the reactor would effect a much higher aggregate UV dose on the fluid than a reactor style without an in-line mixer; the effect magnifies as the UVT properties of the fluid decreases. 
         [0027]    Other applications and adaptations (refer to  FIG. 5 ) include but are not limited to: 
         [0028]    a) Chemical mixing (E.g. sodium hypochlorite with water). In this case, the “quartz sleeve” would be replaced by a pipe with orifice(s) for this description herein referred to as the center pipe. A fluid or chemical (possibly concentrated), pressurized in the center pipe would discharge through orifice(s) into the fundamental flow of fluid between the inlet and outlet piping (previously described). The in-line mixer would then thoroughly mix the induced or injected chemical or substance from the center pipe into the fundamental fluid flow stream. 
         [0029]    b) Gas to liquid mixing (E.g. chlorine gas with water). In this example the “quartz sleeve” would be replaced by a pipe with orifice(s) for this description herein referred to as the center pipe. A pressurized gas in the center pipe would discharge through orifice(s) into the fundamental flow of fluid between the inlet and outlet piping (previously described). The in-line mixer would then thoroughly mix the induced or injected gas from the center pipe into the fundamental fluid flow stream. 
         [0030]    These illustrative examples are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts.