Abstract:
An ozone generator is proposed which comprises a plurality of plate-like ozone generating elements, stacked one on top of the other, which are in at least partial contact with a process water stream, each of the ozone generating elements having at least one plate-like, electrically insulated inner electrode and at least one likewise plate-like counterelectrode, between which a space is provided for a gas discharge. According to the invention, the ozone generating elements are situated at a distance from one another, perpendicular to their plate-like extension, in such a way that process water is able to flow between the ozone generating elements over substantial surface regions of the plate-like ozone generating elements.

Description:
FIELD OF INVENTION  
         [0001]    The invention relates to an ozone generator comprising a plurality of plate-like ozone generating elements, stacked one on top of the other, which are in at least partial contact with a process water stream, each of the ozone generating elements having at least one plate-like, electrically insulated inner electrode and at least one likewise plate-like counterelectrode, between which a space is provided for a gas discharge.  
         BACKGROUND OF THE INVENTION  
         [0002]    An ozone generator having cylindrical plate electrodes in a stacked configuration is known from German Patent 32 47 373 C2, in which two insulating plates are situated between two solid outer electrodes separated at a distance from one another, and an inner electrode is situated between the two insulating plates, forming two discharge chambers. The inner electrode has an outer diameter which is smaller than the diameter of the insulating plates, between which an annular ring running in the vicinity of their edges is clamped. Together with the sealing elements, the stacked electrodes form a cylindrical block which is surrounded by externally flowing process water for cooling.  
           [0003]    To enable the heat generated in the discharge chambers to dissipate, the solid electrodes must be made of aluminum, which allows good outward heat conductance to the process water.  
           [0004]    However, it is this very use of aluminum which causes the heat removal in the aluminum electrodes to be the limiting factor in the design of the allowable maximum capacity.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    The object of the present invention is to provide a more effective design for an ozone generator of the aforementioned type, in particular with respect to the capacity.  
           [0006]    This object is achieved by the features of claim 1.  
           [0007]    Advantageous and useful embodiments of the invention are stated in the subclaims.  
           [0008]    The invention is directed to an ozone generator comprising a plurality of plate-like ozone generating elements, stacked one on top of the other, which are in at least partial contact with process water, that is, water enriched with ozone, each of the ozone generating elements having at least one plate-like, electrically insulated inner electrode and at least one likewise plate-like counterelectrode, between which a space is provided for a gas discharge. The essence of the invention lies in the fact that the ozone generating elements are situated at a distance from one another, perpendicular to their plate-like extension, in such a way that the process water is able to flow between the ozone generating elements over substantial surface regions of the plate-like ozone generating elements. This procedure is based on the knowledge that, in order to provide an ozone generator having a higher capacity with at least the same reliability, the ozone generator must be provided with significantly more effective cooling. By distancing the ozone generating elements from one another, the cooling surface is increased considerably in comparison to the known principle according to German Patent 32 47 373 C2. In this manner the individual ozone generating elements may be operated at significantly higher capacities without overheating, thereby enabling correspondingly more effective ozone generation.  
           [0009]    To achieve even better cooling, it is further proposed that the ozone generating elements be situated and designed in such a way that process water can flow essentially over the entire surface in the region of the gas discharge between the particular ozone generating elements.  
           [0010]    It is also particularly advantageous when the process water is in direct contact with at least one outer electrode of the ozone generating element. In other words, there is no intermediate insulation layer, in particular between the outer electrode and the process water. The effectiveness of the cooling is further increased by use of this measure.  
           [0011]    In a particularly preferred embodiment of the invention, conducting means are provided through which a portion of the process water stream is forced to flow between the ozone generating elements. This procedure further improves the effectiveness of the cooling and thus the capacity of the generator, that is, the maximum possible ozone generation rate. To further improve the cooling, it is also proposed that the conducting means be designed in such a way that the process water flows in a spiral through the intermediate spaces between the ozone generating elements.  
           [0012]    To establish a forced flow between the ozone generating elements in a comparatively simple manner, it is further proposed that the ozone generating elements be at least partially surrounded by a jacket which covers an intermediate space between the ozone generating elements on their front faces, and that recesses be provided in the edge region of the ozone generating elements through which the process water can flow between the ozone generating elements. The jacket may be situated at somewhat of a distance from and outside the ozone generating elements, and for a cylindrical electrode shape, radially outside the ozone generating elements, so that water is not constrained to flow only through the recesses between the ozone generating elements. However, the recesses are preferably dimensioned so that, in comparison to an edge gap between the jacket and the ozone generating elements, the flow characteristics of the cooling water are substantially determined by the recesses.  
           [0013]    In a further embodiment of the invention, it is preferred that the recesses, viewed in the direction of stacking of the ozone generating elements, are offset with respect to one another. The recesses are preferably situated in the edge region of the ozone generating elements, and are offset in such a way that the configuration resembles a stairstep structure when viewed in the direction of the plane of the plates.  
           [0014]    This design is particularly suited for forcing a spiral flow of process water in the intermediate spaces between the stacked ozone generating elements when partitions, for example separating ridges, are provided to ensure circular flow through the intermediate space between the ozone generating elements, from one recess to the next recess in an adjoining ozone generating element, and the flow in the intermediate space situated above, between the adjoining ozone generating element and the subsequent ozone generating element, likewise has a circular design. In other words, speaking in graphical terms, the circular flow along the width, for example, of a recess continues in an offset manner to the next plane, and so forth. Flow preferably passes through the intermediate spaces between all the ozone generating elements until the water stream exits into a process chamber at the top ozone generating element.  
           [0015]    A significant portion of the electrode surfaces may be effectively cooled by this procedure. Thus, it is possible to achieve high ozone generation rates using a comparatively small space. In addition, the number of stacked ozone generating elements is basically unlimited since, with respect to the maximum possible heat removal for a number of ozone generating elements used up to that point, the cooling of the ozone generating elements is far from reaching its capacity limit.  
           [0016]    In a further preferred embodiment of the invention, at least the outer surfaces of the ozone generating elements are made of stainless steel. The outer electrodes are advantageously produced entirely from stainless steel. As the result of the cooling principle for the ozone generating elements via their intermediate spaces, materials may be used which have a considerably lower heat conductivity compared to aluminum, but which have other advantages in contrast to aluminum. The use of stainless steel results in an exceedingly corrosion-resistant design which in turn ensures a comparatively long service life and reliability of the ozone generator. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    Two exemplary embodiments of the invention are illustrated in the drawings, and are explained in greater detail with reference to further details and advantages.  
         [0018]    [0018]FIG. 1 a  shows an ozone oxidizer in a partially cutaway side view;  
         [0019]    [0019]FIG. 1 b  shows an enlarged detail of an ozone generating element according to FIG. 1 a;    
         [0020]    [0020]FIG. 2 shows an ozone generating element of an ozone generating unit according to FIGS. 1 a  and  1   b , in a top view;  
         [0021]    [0021]FIG. 3 a  shows partially mounted stacked ozone generating elements in an oblique perspective view from the bottom; and  
         [0022]    [0022]FIG. 3 b  shows an enlarged perspective view of a detail of the stack of ozone generating elements according to FIG. 3 a.   
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    [0023]FIGS. 1 a  and  1   b  show an ozone oxidizer  1  having a process chamber housing  2  which is sealed with respect to the outside. An ozone generating unit  3  is situated in process chamber  2   a  of housing  2 . A water feed pipe  4  is sealingly inserted in base  2   b  of housing  2 . Water feed pipe  4  merges into a Venturi nozzle unit  5  mounted on the underside of ozone generating unit  3 . Venturi nozzle unit  5  comprises a Venturi nozzle  5   a , inside of which an injector element  6  having discharge outlets  7  is centrally situated. Injector element  6  is attached at separate locations to the underside of a stack of ozone generating elements  8  of ozone generating unit  3  by a valve arrangement  19 . Water flowing in through water feed pipe  4  is led at high velocity past discharge outlets  7 , from which gas having a specified proportion of ozone which has been formed in ozone generating elements  8  flows out.  
         [0024]    Ozone generating elements  8  comprise two outer electrodes  9 ,  10  (see in particular FIG. 1 b ), along each of which, viewed inwardly, a glass plate  11 ,  12  runs as electrical insulation. The glass plates are positioned at a specified interval by spacers (not shown), the intermediate space between the glass plates being sealed gas-tight by a sealing element which runs in a clamped manner along the outer edge. In the region between glass plates  11 ,  12  an inner electrode  15  is situated, preferably centrally, the diameter of which is smaller than that of glass plates  11 ,  12 . Two discharge chambers  13 ,  14  are thus created in which a corona discharge may be established between each of glass plates  11 ,  12  when high voltage is applied to inner electrode  15  and appropriate process gas is led in.  
         [0025]    A high-voltage unit  17  is provided for the high voltage supply which can apply high voltage to the inner electrodes via connecting elements  17   a ,  17   b . Connecting elements  17   b  are each centrally led from inner electrode  15  to inner electrode  15  in a core region  8   a  of ozone generating elements  8 . Core region  8   a  is sealed gas-tight with respect to the outside by outer electrodes  9 ,  10 , sealing elements  16 , and annular wall sections  8   b  (also see FIG. 2).  
         [0026]    For the preparation of process gas, which may be technical grade oxygen, air, or an oxygen-gas mixture, a gas inlet is provided via a valve unit  18  which feeds the process gas under pressure to the gas-tight sealed region of ozone generating unit  8 . A silent electric discharge (corona discharge) is formed by a high voltage applied to the inner electrodes, resulting in the generation of ozone in a known manner. The ozone-enriched process gas is fed to outlet openings  7  of Venturi nozzle unit  5  via valve arrangement  19 , and at that location streams into the process water flowing by.  
         [0027]    Valve arrangement  19  prevents process water from entering the sealed region of ozone generating elements  8  via Venturi nozzle  5 .  
         [0028]    The process water flowing out of Venturi nozzle unit  5  enters a region  20  below stacked ozone generating elements  8 . At this point, part of the process water leaves region  20  in process chamber  2 , through outlet openings  21  in a jacket  24  surrounding the ozone generating elements and region  20 , and can run off via an outlet pipe  22  in process chamber housing  2 . The volume encompassed by jacket  24  is bounded on the lower side by a base plate  24   a  in which Venturi nozzle  5   a  is securely inserted.  
         [0029]    Stacked ozone generating elements  8  are held at a distance from one another by spacers  23 , thereby forming intermediate spaces  26 ,  29  between ozone generating elements  8  up to a core cross section  28  defined by annular wall sections  8   a.    
         [0030]    The portion of the process water which does not leave region  20  through outlet openings  21  is forced to flow through these intermediate spaces  26 ,  29 , and does not exit ozone generating unit  3  until reaching the topmost ozone generating element  8  in process chamber  2   a.    
         [0031]    For the formation of a circular, spiral-shaped water flow through intermediate spaces  26 ,  29  via the stack of ozone generating elements  8 , ozone generating elements  8  have recesses  25   a ,  25   b ,  25   c ,  25   d  at their outer edges which are configured in a stairstep manner, viewed in the direction of jacket surface  24  (see in particular FIGS. 3 a  and  3   b ).  
         [0032]    The stack of ozone generating elements illustrated in FIGS. 3 a  and  3   b  may be used in an ozone generator  1  according to FIG. 1 a.    
         [0033]    Process water is able to flow into intermediate space  26  between the first two bottom ozone generating elements  8  via a recess  25   a . The water entering through recess  25   a  is forced into a circular flow, shown here in the counterclockwise direction as an example, about core cross section  28  by means of a baffle plate  27  and the surrounding jacket  24  (not illustrated in FIGS. 3 a  and  3   b ). In the same manner, an interference in the clockwise direction is also possible. In addition, it is conceivable to reverse the direction of flow from ozone generating element to ozone generating element.  
         [0034]    Baffle plate  27  separates intermediate space  26  from wall section  8   b  approximately to the point of jacket  24 . As before, small gaps appearing toward the outside may be disregarded by appropriate dimensioning in the hydrodynamic sense.  
         [0035]    The water flowing in through recess  25   a  thus reaches the back side of baffle plate  27 . At that point, the water can flow, through a recess  25   b  situated in this segment in ozone generating element  8  situated above, into intermediate space  29  between this ozone generating element  8  and subsequent ozone generating element  8 . A baffle plate  27  likewise situated at that location ensures that the identical circular flow is produced in the clockwise direction. Corresponding recesses  25   c ,  25   d , and so forth are provided with corresponding baffle plates  27  in ozone generating elements  8  situated above, so that a spiral flow is established between ozone generating elements  8  up to the topmost ozone generating element  8 , the spiral flow exiting ozone generating unit  3  into process chamber  2  at the first ozone generating element situated above. This portion of the water as well may then run off through outlet pipe  22 .  
         [0036]    A particularly effective cooling of the ozone generating elements is thus achieved. In this manner the ozone generating elements may be operated in a capacity range which, in a conventional design without intermediate spaces between the ozone generating elements, would result in premature destruction of the ozone generating unit. By operating the ozone generating unit at a higher capacity the ozone generation rate can be significantly increased, so that the ozone generating unit operates much more effectively. In a system performing sterilization using ozone, ozone generating units may thus be conserved, or designed with smaller volumes.  
         [0037]    A further significant advantage of such a design lies in the fact that, on account of the improved cooling, outer electrodes  9 ,  10  of ozone generating elements  8  as well as wall sections  8   b  may be produced from stainless steel. The high corrosion resistance of stainless steel ensures a long service life and high reliability.  
         [0038]    When such an ozone generating unit is used for processing water in swimming pools, the heating of the water during cooling of ozone generating elements  8  contributes to heating the water in the swimming pool as well.