Abstract:
The invention relates to a device for purifying water contaminated with organic substances, which is drained or collected from filters, especially fuel filters or elements of a fuel system. Hydroxyl radicals are formed from the water by means of a separating device where the hydroxyl radicals oxidize the impurities, especially organic substances, as much as possible, and convert them into compounds such as CO 2 .

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for purifying water drained or collected from filters, especially fuel filters or elements of the fuel system, where the water is contaminated with organic matter. 
     BACKGROUND OF THE INVENTION 
     In order to ensure the operational reliability of drive units, such as in particular internal combustion engines, which are supplied with liquid fuels, it is conventional practice to provide fuel supply systems with water-separating fuel filters. The separation of water which is contained or entrained fuel and in particular in diesel fuel is required to protect the sensitive injection system from damage. The water which has been separated in these systems is loaded with various types of organic matter, for example, with suspended droplets of oil from the diesel fuel flowing through the fuel filter. Therefore, for reasons of environmental protection, the release of water which has been separated from the fuel filter systems into the environment without further treatment is not an option. 
     SUMMARY OF THE INVENTION 
     Accordingly, one object of the present invention is to provide a device for purifying water which has been separated from a fuel supply systems, where the device, can be easily and economically operated, and enables effective removal of the organic loads so that the purified water can be released into the environment quite safely. 
     Accordingly, the important feature of the is the device having a separating means by which hydroxyl radicals can be separated from the water to be purified, so that said hydroxyl radicals oxidize the organic matter contained in the water as much as possible into inorganic compounds such as CO 2 . Since hydroxyl radicals are chemically highly reactive, they are able to develop such a high oxidation potential that organic loads such as, for example, oil-water emulsions or suspended diesel droplets in the water which has been separated from diesel fuel filters are oxidized almost completely into CO 2 . 
     In especially advantageous exemplary embodiments, the separating means has an electrolysis apparatus and/or hydroxyl radical-forming media, for example, catalysts such as titanium dioxide. 
     When the hydroxyl radicals are produced by splitting water by means of electrolysis, the configuration can be made especially advantageously such that the electrolysis apparatus has at least one diamond electrode which is anodically active during electrolysis. Water decomposition can be achieved by means of a diamond electrode which is electrically conductive by doping with the element boron. While water is typically split into hydrogen and oxygen during electrolysis, the diamond electrode provides a working range in which highly reactive hydroxyl radicals are formed instead of oxygen and hydrogen. 
     In advantageous exemplary embodiments, the electrolysis apparatus can have two diamond electrodes which, when energized with polarity reversal, the electrodes function alternately as an anode and as a cathode. This device with two diamond electrodes can be operated, with alternating current. 
     If alternatively a diamond electrode is acting as anode for the electrolysis, a high-grade steel electrode is preferably used as the cathode. The steel electrode is subjected to cathodic protection during electrolysis according to the method of electrochemical protection, as is used for corrosion protection, for example, in tanks or ships. 
     Preferably, the arrangement is made such that the device has a treatment chamber downstream of the pertinent fuel filter for the water which is to be purified. The chamber has a controllable outlet or conveyor device or overflow for the purified water as well as the separating means in order to make contact between the water in the treatment chamber and the hydroxyl radicals which have been formed in the chamber. 
     As an alternative to the arrangement of the electrolyzing electrodes, the separation means can have a body which is located in the treatment chamber and in contact with the water. The body contains or is coated with titanium dioxide and forms the hydroxyl radicals when in contact with the water. 
     In especially advantageous exemplary embodiments, it is furthermore provided that the separating means, preferably in addition to the part of the means which produces hydroxyl radicals and which is located in the treatment chamber, has a filter medium which is provided with titanium dioxide for the formation of hydroxyl radicals in the associated fuel filter. 
     To promote the formation of hydroxyl radicals by titanium dioxide, the separating means can have a means for supplying radiant energy. For this purpose, there can be an artificial or natural light source, preferably with wavelengths from 180 to 300 nm. 
     Depending on where the formation of the hydroxyl radicals by titanium dioxide takes place, a radiation source of this type can be provided for irradiation of the treatment chamber and/or of the interior of the fuel filter. 
     Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses various embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following is a brief description of the drawings in which: 
         FIG. 1  is a schematic diagram of one exemplary embodiment of the device according to the invention, and 
         FIG. 2  is a schematic diagram of a second exemplary embodiment of the device corresponding to  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is explained below using examples in which the purification device  2  is integrated into the fuel supply system such that water  6  which has been removed from a water-separating fuel filter  4  is drained directly into a tank  8  of the device  2 , which tank forms a treatment chamber. Alternatively, the purification device  2  can also form a unit which is separate from a fuel supply system and in which captured water is purified. 
     In the examples described here, the fuel filter  4  is located in the route of the fuel line  10 , and fuel, for example, diesel fuel, flows through the filer before it is delivered to a system to be supplied (not shown), for example, the injection pump of a diesel engine. The water  6  which has been separated in the filter  4  is drained directly into the tank  8  of the device  2 . The tank  8  forms a treatment chamber for the drained water  9  with a controllable drain  12  and a controllable outlet  14  by means of which a feed amount of water  9  to be purified for a specified treatment interval is maintained using level sensor means which are conventional in the art and where the water is released after the purification is completed. 
     In the two exemplary embodiments of  FIG. 1  and  FIG. 2 , the water  6 ,  9  originating from the fuel filter is purified by the oxidation of organic loads by bringing these loads into contact with highly reactive hydroxyl radicals in the tank  8 , which is used as a treatment chamber. In the two exemplary embodiments, the hydroxyl radicals are split off from the water molecules in the tank  8 , using a separating means. In the exemplary embodiment of  FIG. 1 , water decomposition takes place by electrolysis, which is carried out by means of two diamond electrodes  16  and  18 . While water typically is split into hydrogen and oxygen during electrolysis, a diamond electrode  16 ,  18  yields a working range in which highly aggressive hydroxyl radicals are formed instead of oxygen. 
     The diamond electrodes  16 ,  18  can be formed such that a crystalline diamond layer of only few microns thick obtained from hydrogen gas and a hydrocarbon gas such as methane is applied to a conductive substrate at very high temperatures between 2000° C. and 3000° C., rendering the diamond layer electrically conductive by doping with the element boron. 
     If, as in the exemplary embodiment of  FIG. 1 , the two electrodes  16  and  18  are diamond electrodes, electrolysis can take place by applying an AC voltage whereby, corresponding to polarity reversal, one electrode  16  or  18  at a time acts as an anode and the other electrode  16  or  18  as a cathode. Alternatively, the arrangement can be made such that only one of the electrodes—in the example shown in  FIG. 1 , the electrode  16 —is a diamond electrode and is connected to the positive terminal  20  of a DC voltage source. In this case, the electrode  18 , which is connected to the negative terminal  22  and which is acting as cathode, is a high-grade steel electrode. In operation, a cathodic protection occurs for the electrode  18  acting as cathode, corresponding to conventional methods of electrochemical protection for corrosion protection of tanks or ships. 
     In any event, the high oxidation potential of the hydroxyl radicals which have been formed ensures that the organic substances found in the water are oxidized into harmless inorganic compounds, especially into CO 2  which escapes from the tank  8 . The purified water can then be safely released into the environment. 
       FIG. 2  shows one example in which a chemical separating means is used instead of a separating means made as an electrolysis apparatus, specifically such that a titanium dioxide-containing body  30  located in the tank  8  is brought into contact with the water  9  to be purified. Making contact with titanium dioxide results in the splitting of hydroxyl radicals from the pertinent water  9 . As has been found, this chemical mechanism can be enhanced by a supply of radiant energy. The supply of radiant energy can take place by an artificial or natural light source  24  which irradiates the contents of the tank within the tank  8 . A wavelength range from 180 to 300 nm has proven especially effective. The light source  24  can be sunlight, lights such as LEDs, or the like. 
     In the two exemplary embodiments of  FIG. 1  and  FIG. 2 , it can also be provided that the fuel filter  4  is provided with a filter medium  26  which has a coating with titanium dioxide so that a separating means for splitting off hydroxyl radicals from the water  6  is already formed in the fuel filter  4 . The resulting purification can replace the water purification in the tank  8  or in addition thereto can be provided as a preliminary purification. As in the separating means within the tank  8 , there can also be an arrangement for the supply of radiant energy as a reaction enhancement means for the separating means formed in the fuel filter  4 , in this example another light source  28 . 
     The invention enables effective purification with a device which is simple to operate and which does not require any consumable materials, but simply requires a supply of electrical energy for electrolysis or optionally for radiation sources in the form of light sources  24 ,  28 . 
     While various embodiments have been chosen to illustrate the invention, it will be understood that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.