Abstract:
An ozone generator comprises an electrode located within a dielectric tube with a ground electrode formed on the outer surface of the tube. The tube and ground electrode are surrounded by a coding jacket to allow the coolant to come into contact with the ground electrode and provide efficient cooling.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of U.S. utility patent application Ser. No. 09/730,319, filed Dec. 4, 2000 (the &#39;319 application), pending, which in turn corresponds to and claims priority to Canadian Application No. 2,291,525, filed Dec. 3, 1999 (the &#39;525 application). The &#39;319 and &#39;525 applications are hereby incorporated by reference as though fully set forth herein. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    a. Field of the Invention The present invention relates to an ozone generator.  
           [0003]    b. Background Art  
           [0004]    Ozone is a gas that has an aggressive oxidizing action and is used among other things to sterilize water. In this application the gas is bubbled through the water and contaminants are oxidized and may be removed during the subsequent processing.  
           [0005]    Ozone may be generated by subjecting an oxygen bearing gas, typically air, to a high intensity electric field. The electric field is applied by imposing a high frequency voltage between a pair of electrodes as air passes between the electrodes.  
           [0006]    The application of the high voltage at high frequency generates significant heat which must be removed by cooling. In typical installation the voltage is applied to an active electrode and the electric field established between the active electrode and a ground electrode. The electrodes face each other and the gas is passed between them to generate the ozone. The ground electrode is supported on an insulating structure which in turn is encompassed by a cooling jacket.  
           [0007]    The application of high frequency current to the electrode produces significant heat which in turn must be removed efficiently by the cooling jacket. The efficiency of the ozone generation is in part a function of the temperature of the gas and accordingly efficient heat removal is a prime consideration. However the support of the electrode within an insulating structure inhibits heat transfer from the ozone-producing region and thereby limits the efficiencies that may be attained in conventional apparatus.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    It is therefore an object of the present invention to provide an ozone generator in which the above disadvantages are obviated or mitigated.  
           [0009]    In general terms the present invention provides an ozone generator comprising an active electrode to be connected to a power supply, a housing encompassing said electrode to define an enclosed chamber through which gas can flow and having a wall formed from a dielectric material, a ground electrode disposed on the opposite side of said wall to said electrode and a coolant contacting said ground electrode to remove heat therefrom. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which  
         [0011]    [0011]FIG. 1 is a side view, partly in section of an ozone generator.  
         [0012]    [0012]FIG. 2 is an enlarged view of a portion of the generator shown in FIG. 1.  
         [0013]    [0013]FIG. 3 is a section on the line  3 - 3  of FIG. 2. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    Referring therefore to FIG. 1, an ozone generator generally indicated  10  includes an outer tubular body  12  extending between a pair of T fittings  14 . Each of the T fittings  14  has an end cap  16  with a through bore  18  to receive a support tube  20 . The support tube  20  is formed by a wall of a dielectric material, typically ceramics and extends through the body  12  to project beyond each of the end caps  16 . The tube  20  and the body  12  in conjunction with the end caps  16  define a cooling chamber  22  through which water can circulate from an inlet port  24  in one branch of one of the fittings  14  to a corresponding outlet port  25  on the other fitting. The tube  20  extends through a protective boss  26  to a second T fitting  28 . The fitting  28  has a gas inlet port  30  that receives a supply of oxygen gas and a sealing plate  32  in the branch aligned with the tube  20 . The sealing plate  32  supports an electrical conductor  34  that is connected to a high voltage oscillating power source  36 . The power source  36  is a power unit available from Plasma Technics Inc. of Rancine, Wis. and provides a 6-kilovolt supply at 20 kilohertz.  
         [0015]    The conductor  34  passes through the interior of the tube  20  and is connected to an electrode  38 . The electrode  38  comprises a stainless steel wire mesh that is supported on a cylindrical dielectric rod  40  within the tube  20 . The mesh  38  is wrapped about the rod  40  and provides a sliding fit within the interior of the tube  20 . The interweaving of the mesh  38  provides voids through which the gas may pass from the inlet  30  along the interior of the tube to an outlet  42  in the opposite end fitting  14 .  
         [0016]    A ground electrode  44  is formed on the outer surface of the tube  20  from a conductive epoxy coating. Typically the electrode  44  is a silver filled epoxy such as that available from Chomerics Div. of Parker Hannifin Corp. of Wolbum, Me.  
         [0017]    The ground electrode  44  is connected through cable  46  to a ground terminal  48  provided in the fitting  14 .  
         [0018]    In operation, oxygen bearing gas typically air or air enriched with oxygen is fed through the inlet  30  and along the interior of the tube  20  to the outlet  42 . Power is supplied from the power supply  36  to the electrode  38  to generate an alternating electric field between the electrodes  38 ,  44 . As the gas passes the electrode a portion of the oxygen in the gas is converted to ozone and passing through the outlet  42 .  
         [0019]    The heat generated is removed by water flowing through the inlet  24  and through the chamber  22  to the outlet  25 . The water is in intimate contact with the ground electrode  44  and thus provides an efficient heat removal.  
         [0020]    During operation, the close fit of the grid between the rod  40  and the tube  20  promotes turbulence in the gas flow to facilitate the conversion process. In preliminary tests, ozone generation in the order of 10 grams per hour has been achieved using a 6-kilovolt 20 hertz supply. In this arrangement, the radial spacing between the support  40  and tube  20  is in the order of 1.5 millimeters with a diameter of the rod  40  is approximately 6 millimeters. The efficiency of the cooling provided by the chamber  22  is such that the body  12  and fittings  14  may be made from PVC and the fittings in contact with the ozone are made from kynar. However it should be noted that as the cooling and ozone generation functions are separated by the tube  20  the fittings on the cooling jacket may be conventional PVC fittings.  
         [0021]    The dielectric tube  20  and rod  40  are preferably an alumina ceramic AD 998 available from Coors Ceramics Company, Golden, Colo. or an equivalent material.  
         [0022]    Enhanced performance from the generator may be obtained by utilizing oxygen rather than air as a feed or enriching an air stream with oxygen. An improved performance may also be attained by chilling the coolant flow to maintain the ambient temperature of the air at a minimum.  
         [0023]    The generators  10  may be arranged in an array with similar units, either in series flow or parallel flow, to provide the requisite mass flow.  
         [0024]    Alternative coolants may be used to water including air if sufficient heat transfer can be attained.