Abstract:
An ozone generator to produce highly pure ozone gas which uses ordinary water for the low voltage electrode and for directly cooling the glass dielectric and utilizing a high frequency resonant circuit and a threaded rod high voltage electrode of which the pitch and depth can be varied to improve performance efficiency and reliability.

Description:
BACKGROUND Of THE INVENTION  
         [0001]    Ozone, O 3 , is made from stable oxygen, O 2 , and has many widespread industrial applications including the destruction of organic and inorganic contaminants in waste water and sludge disinfection, environmentally friendly bleaching of paper, etching surfaces of semiconductors, decolorizing water, removing odour from clothing and killing insects, to name but a few.  
           [0002]    Since ozone is unstable at ambient temperatures and decomposes quickly, it must be manufactured on site for industrial applications. Two general techniques in ozone production ate currently available. One utilizes electrochemical techniques to generate ozone atoms, requiring electrochemical cells composed of an anode and a cathode conducting electricity through a solution or a solid. This technique produces toxic by-products which can be difficult to dispose of. The second general technique utilizes an electrical discharge to generate ozone atoms, requiring that a discharge passes through an oxygen gas and converts oxygen to ozone.  
           [0003]    Industrial ozone generators using tubular electrodes are generally composed of elementary electrodes connected in parallel, each electrode being composed of a cylindrical glass dielectric, which is closed at one end and coated with a metallic coating on its interior, An annular space is formed between the outside of the dielectric and the interior of the larger diameter metallic cylinder. The exterior of the metallic electrode is cooled wild water. A gas containing oxygen is passed through the annular space and a high alternating voltage is applied to the inner metallic coating. The outer electrode is carth grounded for safety and the voltage supplied to the inner electrode is ether stepped up from the n supply or through a DC/AC inverter.  
           [0004]    Both of the above techniques suffer from high electrical consumption and low conversion efficiencies There exists other specific methods of producing ozone using high energy methods, for example, UV lights, beta rays or lasers, to convert oxygen to ozone but these methods have not found significant commercial application.  
           [0005]    Current applications of ozone are limited by the cost of instrumentation required, as well as the previously mentioned high consumption of electricity during ozone production and the low efficiencies of converting oxygen to ozone. Furthermore, over the years, significant efforts have been made to refine ozone generators and the power supplies which form an integral par of their operating circuitry. These efforts have been particularly directed at increasing their efficiency to reduce their cost of operation and the cost of manufacture of ozone per unit of power consumed. May factors have contributed to setting prior art limitations of efficiency, including tie characteristics of the voltage and current periodic waveforms.  
           [0006]    It is clear that there exists a need for a new and improved apparatus for improving the ozone generating efficiency of current devices and methods.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention overcomes the above shortcomings.  
           [0008]    Briefly, it is an object of the present invention to provide an ozone generator wherein the capacitance and surface area of the inner electrode are adapted thereby resulting in improved ozone generating efficiency.  
           [0009]    A further object of the present invention is the novel means providing a self-resonant center tapped high voltage transformer using only two switching devices for inversion of the DC supply voltage.  
           [0010]    To achieve the foregoing objects, the present invention provides an ozone generator, comprising: a high voltage source including means for connecting to electrodes; an ozone generating tube constructed of a high voltage threaded rod electrode having variable pitch and depth, a ground electrode and an unmetallized cylindrical glass dielectric positioned between said high voltage electrode and ground electrode; a gas inlet pipe for feeding oxygen to said ozone generator; a water jacket for cooling said ozone generator; and an ozone outlet pipe for delivering resulting ozone gas from said ozone generator to a desired location for use.  
           [0011]    A still further object of the present invention is to provide a current source inverter power supply circuit for supplying an ozone generator, comprising: a AC/DC semiconductor switch bridge rectifier coupled at its input terminals to an alternating current power source and at its output terminals to an electrical network, commutating capacitors; said electrical network having a step up high voltage transformer forming a resonant circuit; and transistors switched via feedback winding; wherein a self-resonant center tapped high voltage transformer using switching devices for inversion of the DC supply voltage is provided for coupling to the ozone generator.  
           [0012]    Further objects and advantages of the present invention will be apparent from the following description, wherein preferred embodiments of the invention are clearly shown. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The present invention will be further understood from the following description with reference to the drawings in which:  
         [0014]    [0014]FIG. 1 is a front cross-sectional view of a ozone generator in accordance wit the present inventions FIG. 2 is a transverse cross-sectional view tale along line A-A of FIG. 1 showing one of the ozone generator segments;  
         [0015]    [0015]FIG. 3 is an enlarged view of section B of FIG. 1 showing the threaded rod;  
         [0016]    [0016]FIG. 4 is a circuit diagram of an exemplary embodiment of a solid state power supply and control circuit for an ozone generator in accordance wit the present invention;  
         [0017]    [0017]FIG. 5 is a cutaway perspective view of all exemplary ozone generator assembly in accordance with the present invention  
         [0018]    [0018]FIG. 6 is a graph showing the results of ozone production relative to the amount of power applied with an unthreaded rod; and  
         [0019]    [0019]FIG. 7 is a graph showing the results of ozone production relative to the amount of power applied with a treaded rod in accordance with tile present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    Generally shown in FIGS.  1  to  3 , ozone generators  10  of the type contemplated herein generally include an outer casing or housing  12 , a ground electrode  14  formed with a lining of its inner surface with glass  16  by way of welding or the like. The resulting cylindrical glass dielectric  16  is interlaid between the ground electrode  14  and a high voltage electrode  18 . The cylindrical glass dielectric  16  is cooled on its outside wits water which passes over the unmetallized cylindrical dielectric  16  in a water jacket. The water should have some mineral content for electrical conductivity and ordinary tap water generally has sufficient mineral content for that purpose. Further, the dielectric  16  need not be coated with a metallized film since the water will act as a conductor. The inner, high voltage electrode  18  is made from a metallic threaded rod, fox instance SUS  316  stainless steel, The threaded rod  20  tread pitch and depth can be varied to achieve different level of performance which may improve the efficiency of the discharge even Her. The inner rod  18  is held coaxially within the glass dielectric  16  with TEFLON™ or similar material O-rings  22 . The headed rod  20  reduces the capacitance and surface area of the electrode  18 .  
         [0021]    Describing the power supply structure to the high voltage electrode  18 , reference will be made to key parts of FIG. 4. The power supply circuit for supplying the ozone generator  10  comprises a AC/DC semiconductor switch bridge inverter  44  (BR 1 ) coupled at its input to an alterative current power source and at its output to the electrical network which includes filtering capacitor  45  (C 1 ). This voltage is modulated by transistor  48  (Q 3 ) and passes through diode  53  (D 5 ) to the inductor  46  (L 1 ). The smoothing inductor  46  connects to the center tap of the high voltage transformer. The DC voltage modulation is accomplished by the voltage regulator integrated circuit  47 . Potentiometer  51  (P 2 ) adjusts the DC voltage from 2 to 30 VDC. Resistor  55  (R 1 ) serves as a current measuring device shunt, which feeds back into  49  (Q 1 ) for setting he current limit, the current limit being ultimately set by potentiometer  50  (P 1 ). The power circuit is made up of a DC power supply delivering DC voltage to the center tap of a high voltage step up transformer  40 . A smoothing inductor is placed in series between the DC voltage and the centre tap transformer. The transformer characteristics are adjusted to form a resonant circuit with the capacitive load of the generator cell to resonate at a desired frequency. This frequency can be from 1 to 40 kHz. Each leg of the transformer  40  is connected through a transistor  42 . The transistors are switched via a feedback winding in the transformer  40 . Without the load connected the circuit oscillates at a higher frequency. When the ozone generator  10  capacitive cell is connected the frequency self adjusts to a lower frequency depending on the total capacitance and the saturating characteristics of the transformer  40 . The air gap of the transformer  40  will also affect the resonant frequency. The result is a self-resonant center tapped high voltage transformer using only two switching devices for inversion of the DC supply voltage.  
         [0022]    The power source as described above is connected across the electrode  18  to produce ozone in the channels formed in the space between the electrodes. Air is then blown or drawn through the ozone generator  10  by means of a blower or fan to discharge the ozone eider into or onto the product or material to be treated.  
         [0023]    In FIG. 5, an ozone generator module is schematically shown having interconnected a power entry module  50 , a DC section of power supply board  52  an inverter section  54  of power supply board, a supply transformer  56 , a high voltage transformer  58 , said resulting high voltage Fen being fed to the ozone generator  10  via the high voltage cable  60 . A gas inlet pipe  62  and an ozone outlet pipe  64  are specifically provided, respectively, on the upper side and the lower side of the module since the ozonized gas is greater in specific gravity than oxygen and therefore tends to stay on the bottom. Further, cooling water inlet  66  and outlet  68  are provided forming a U-shaped cooling water passage in the water jacket of the ozone generator  10 . The corona discharge cell  70 , combined to passing gaseous oxygen or air though a high voltages provides for molecular oxygen (O 2 ) disassociating into atomic oxygen in an energizing environment that allows the recombination of atoms into ozone (O 3 ) form. A cooing air inlet filter  72 , an outlet fan  64  and a flow meter  76  are also provided for measuring and ensuring peak performance,  
         [0024]    Next, operation characteristics of the ozone generator  10  of the above construction will be described. Referring to FIGS. 6 and 7, it can be seen that tests were performed in order to evaluate tie performance of the unthreaded and threaded rods in a similar applied power range. Oxygen flow, oxygen pressure, cooling water flow and cooling water temperature were maintained at the same levels, more or less 5%, for all of the tests, The test results are revealing. A linear curve was fitted to both the unthreaded and threaded rod data. As shown on the figures, the rate of production increase versus the applied power was 50% higher in the case of the threaded rod as compared to the unthreaded one. It follows that a particularly important increase in efficiency will help reduce the cost of operation of the ozone generator and the cost of manufacturing of ozone per unit of power consumed,  
         [0025]    The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of e claims are therefore intended to be embraced therein.