FI77007B - ANORDNING FOER RENING AV EMULSIONER OCH FOERORENADE VATTEN, SPECIELLT AV OLJEHALTIGA VATTEN MED TILLHJAELP AV ELEKTROLYS. - Google Patents

Description

77007

Apparatus for the purification of emulsions and contaminated waters, in particular oily waters, by electrolysis

The invention relates to an apparatus for purifying emulsions and contaminated water by tip-gap electrolysis, which apparatus comprises electrodes superimposed in a reactor vessel and forming a gap between them, at least one of which is a soluble material and separated from each other by a spacer.

A device such as that mentioned above is known from F1 patent publication 55 166. It uses a soluble aluminum electrode as the second electrode and a plate, trough and drum or other similar fixed structure as the second electrode, mainly a cathode. In this known method, electrolytic purification is effected by causing the liquid to be purified to flow along the second electrode through the tip gap formed by the electrodes so that the tip gap is not immersed in the liquid to be treated. This provides a narrow or small cross-sectional current path with a relatively high current density. With this and also with the smallest possible radius of curvature of the tips, the so-called a peak effect which very effectively causes the impurities in the liquid to be purified to flocculate, whereby they can be removed from the liquid by conventional methods. According to said FI patent publication, it is proposed to use one or more anodes, for example wire-like or plate-like, arranged in a position perpendicular or oblique to the cathode, for example made of stainless steel in the form of a trough, a plane, a rotating roller or a plate. Thus, with such an apparatus, very high overall cleaning efficiencies cannot be achieved, and on the other hand, the feeding of wearing anodes requires automatic apparatus, which makes the structure of the apparatus complicated, especially when several anodes are used. Thus, due to its structure, the apparatus 35 is not very suitable for use in industrial, large-scale treatment of contaminated water as such.

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The object of the present invention is to eliminate the above-mentioned problems and to provide an apparatus by means of which large-scale and efficient cleaning of contaminated water can be carried out without, however, using complicated control and adjustment arrangements. This is achieved by a device according to the invention, characterized in that the spacer is a liquid permeable insulating plate and determines the tip gap between the electrodes, that the insoluble electrode is a liquid permeable mesh, perforated plate, grating or the like adapted to rest by gravity on and that the soluble electrode is permeable to the passage of liquid and dissolves from its surface against the spacer where the discharge takes place. By means of said spacer, the distance between the electrodes can be kept at a value which is advantageous for the generation of said tip effect. On the other hand, the superimposition of the electrodes has the advantage that the actual adjustment of the electrode distance is not required, because the upper electrode automatically moves to the desired distance 20 by gravity within the electrodes (dissolving) as long as the electrode power supply arrangement is implemented to allow this movement. Preferably, the soluble electrode, most often the anode, is formed of electrically arranged electrode plates or a uniform web by twisting it into a helical shape.

The device according to the invention will now be described in more detail with reference to the accompanying drawing, in which Figure 1 schematically shows the structure of the device according to the invention and Figure 2 shows in more detail an embodiment of the electrode arrangement used in the device.

Figure 1 schematically shows the structure of the device according to the invention, in which the electrodes 4 and 6 are placed inside the reaction vessel 1. The liquid to be purified is fed to the reaction vessel 1 through an opening 8 formed in its lower end, and the purified liquid is removed from the reaction vessel 1 through the outlet 9. In electrolytic cleaning,

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3 77007 dented flocs are removed from the reaction vessel 1, for example through an outlet 10 located at the top of the vessel. The reactor vessel 1 is formed of an insulating material in order to avoid a short circuit between the anode 4 and the cathode 6 arranged therein. In the embodiment according to Figure 1, the anode 4 of soluble material is formed of parallel-arranged aluminum plates which are arranged on a porous, liquid-permeable and flow-balancing plate 3. The purpose of the plate 3 is to provide a uniform flow 10 over the entire cross-section of the anode 4 and, on the other hand, to provide a flow rate which is advantageous for electrolytic cleaning. In order to further ensure an even distribution of the flow, suitable distribution channels can be arranged in addition to the conical lower part 2 of the reactor vessel 1. A cathode weight-resistant and liquid-permeable spacer 5 is arranged on the anode 4 of soluble material, which provides the desired tip gap between the anode 4 and the cathode 6. The spacer 5 may be made of various materials, such as sintered cullet or so-called plastic material, or it may be a lattice, grating, carpet, fibrous structure or ceramic plate. The properties required of the board are, on the one hand, sufficient liquid permeability and, on the other hand, electrical insulation. A cathode 25 6, which may be a grating, a perforated plate, a mesh or other liquid-permeable structure made of metal, which acts as an insoluble cathode in electrolytic cleaning, is placed on top of the spacer 5. Current is supplied to the cathode through a conductor 7 introduced into the reactor vessel 1 through a flotation outlet 10. Since the cathode 6 rests gravity on the spacer 5, which in turn rests on the anode 4, the tip gap always remains desired despite the wear of the anode. However, the structure of the cathode should be such as to allow uniform dissolution of the anode. This purpose is also served by a pressure and flow equalizing plate 3 placed under the anode 4. This plate 3 can also be a mat, a fibrous structure, a ceramic plate or the like which passes through the liquid to be cleaned and which provides a favorable pressure on the anode side for electrolysis. This component could also be considered to be formed, for example, by means of a sand mattress.

Figure 2 illustrates in more detail the anode 4 and its power supply structure. In the embodiment of Figure 2, the anode 4 is adapted to rest on a support structure 11 which at the same time acts as a power supply part for the anode 4. The anode 4 is illustrated in Figure 2 to consist of vertically arranged electrode plates 12. These plates may preferably be about 10-20 mm thick and made of soluble material, such as for example, aluminum. In the embodiment of Fig. 2, the pressure equalizing member 3 is described as being fixed to the lower surface of the anode support structure 11. An electrode tip adjusting plate 5 is arranged on the anode 4 and a cathode 6 is arranged to rest on it, to which current is supplied by a conductor 7.

Since the soluble anode in the electrolysis device according to the invention has a fixed position, it can be implemented very massively. When the anode is worn out, it can be simply replaced by lifting the entire electrode package from above or by disconnecting the reactor vessel at the anode support structure 11 by opening the bolts 13 shown in Fig. 2, whereby the new anode can be easily placed. Since the reactor vessel 1 is columnar and relatively high, its structure is advantageous from the point of view of floc formation, since the floc has time to form well in the liquid column inside the vessel 1.

Although the embodiment described above may be considered the most preferred in most cases, it will be appreciated that the idea of the invention, i.e. to provide a tip gap using a porous plate and an electrode adapted to rest thereon, can be applied in many ways other than those described above. This applies in particular to the structure and relative order of the electrodes. Thus, both electrodes could be imagined

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5 77007 of soluble material, in which case they could be fed, for example, with a direct current of varying polarity to prevent passivation. Likewise, one could imagine an insoluble cathode to be placed in the lower reactor vessel and a soluble anode to rest thereon, although such an arrangement is probably less favorable than the arrangement described in Figures 1 and 2. It should also be mentioned that the electrolytic cleaning device according to the invention is intended to be placed primarily as part of an industrial cleaning process, the purified liquid leaving it being further treated in other suitable units, such as oxidation with insoluble electrodes and polyelectrolyte feed and floc removal. A preferred embodiment could be an arrangement in which the reaction vessel 1, cut off, for example at the height of the outlet 9, is placed in a larger vessel surrounding it, whereby the liquid removal can be carried out from the inlet 8 level and the flocs 20 can be removed from the upper end of the outer treatment vessel.

The invention has been described above with the aid of only one exemplary embodiment, and it is to be understood that changes other than those mentioned above may be made without departing from the scope of the appended claims.

Claims (4)

6 77007 An apparatus for purifying emulsified and contaminated water 5 by tip-gap electrolysis, the apparatus comprising electrodes (4, 6) superimposed on the reactor vessel (1) and forming a gap between them, at least one (4) of which is a soluble material and separated by a spacer 10 (5), characterized in that the spacer (5) is a liquid-permeable insulating plate and defines the tip spacing of the discharge between the electrodes (4, 6), that the insoluble electrode (6) is a liquid-permeable mesh, perforated plate, grating or the like rest 15 by gravity on the spacer (5) and that the soluble electrode (4) is permeable to the passage of liquid and dissolves from its surface against the spacer (5) where the discharge takes place. Device according to Claim 1, characterized in that the soluble electrode (4) is formed by electrode plates (12) arranged in a vertical position. Device according to Claim 1, characterized in that the soluble electrode (4) is formed from a unitary web by twisting it into a helical shape 25. Device according to Claim 1, characterized in that a fluid-permeable spacer (3) is arranged in front of the electrodes (4, 6), on the inlet side of the flow, in order to equalize the pressure and the flow in the discharge gap (5). Il