Abstract
The invention concerns an electrolytic reactor, in particular for separating phosphate from phosphate-containing liquids and recovering phosphate salts, comprising a housing, an inlet and an outlet for the liquid and two electrodes of different polarity, which enclose a reactor chamber between them, whereby at least one of the two electrodes is a sacrificial electrode and consists of a magnesium-containing material, whereby the sacrificial electrode is constructed of trapezoid bars which have a first and a second upper surface, whereby the first upper surface is smaller than the second upper surface, and whereby four lateral surfaces connect the first upper surface with the second upper surface.
Claims
1. Electrolytic reactor for separating phosphate from phosphate-containing liquids and recovering phosphate salts, comprising a housing, an inlet and an outlet for the liquid, and first and second sacrificial magnesium anodes which enclose a reactor chamber between them where the liquid may flow in a direction, characterized in that each of the anodes are constructed of trapezoid bars which have a first upper surface and a second upper surface, whereby the first upper surface is smaller than the second upper surface, and four lateral surfaces which each connect the first with the second upper surface, characterized in that the trapezoid bars for building a continuous surface are alternately arranged with the first and second upper surface facing the reaction chamber and complement each other in form.
2. Reactor according to claim 1, characterized in that the trapezoid bars have a longitudinal direction and in terms of their longitudinal direction are arranged transverse to the flow direction of the reactor chamber.
3. Reactor according to claim 1, characterized in that the reaction chamber has a rectangular cross-section in the flow direction and a constant cross-section dimension throughout the entire reaction chamber.
4. Reactor according to claim 1, characterized in that one anode is movable relative to the other anode such that the spacing between the two anodes is constant.
5. Reactor according to claim 1, characterized in that the trapezoid bars of the anodes form a rectangular surface facing the reactor chamber.
6. Reactor according to claim 1, characterized in that the anodes can be alternated to act as anode and as cathode.
7. Reactor according to claim 4, characterized in that the movable anode is contacted via a flexible contact strip or a flexible contact chain that is in contact with every one of the trapezoid bars.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Other advantages and characteristics of the invention are shown in the following drawings where
(2) FIG. 1 shows a longitudinal section through a magnesium bar in view (a) and a cross-section thereof in view (b),
(3) FIG. 2 shows a first electrode design,
(4) FIG. 3 shows an alternative electrode design, and
(5) FIG. 4 shows an arrangement of the upper and lower electrode,
(6) FIG. 5 shows an electrode in top view, and
(7) FIG. 6 shows a sectional view through the bars of the upper electrode with intended contacting,
(8) FIG. 7 shows two views of inventive reactors.
DETAILED DESCRIPTION
(9) FIG. 1 shows a longitudinal section through a commercially available magnesium bar with a smaller upper side 1 and a larger upper side 2, whereby the two lateral surfaces 4 and 5 between the upper surfaces 1 and 2 are shown in Fig. (a) and (b). The bar is all-round trapezoid.
(10) FIG. 2 illustrates the alternate laying of the bars where the upper surface 1 and the upper surface 2 are alternating depending on the assembly situation. Due to the alternate laying of the bars whose side surfaces 5 have the same slant, a plane upper surface 10 results which serves to delimit the reaction chamber and as the upper surface of an electrode. The slanted parts of the lateral surfaces 4 and the slant of the outermost lateral surfaces 5 (here shown as 5a) have the effect that the plane surface in the edge regions cannot be completely maintained. However, the portion of this edge region is less than 5% of the total surface and can therefore be neglected, such that the electrode surface can be called a plane surface 10. Apart from that it is also possible to connect further rows of bars, as shown in FIG. 3, with the result being an electrode 12 with a plane surface. In this case, depending on the arrangement, there can also be regions between the rows of all-round trapezoid bars which deviate from the plane surface. These regions are shown here as 4a. However, according to the invention, the total of all these regions is smaller than 5% of the total surface 10 of electrode 12.
(11) The flow direction of a medium is indicated by reference number 14.
(12) Such magnesium electrodes are used in particular to separate phosphate from phosphate-containing waste water where they serve as sacrificial electrodes in the reactor.
(13) FIG. 4 shows the arrangement of two electrodes 12 and 16, whereby electrode 16, which is the upper electrode in the drawing, is movable in the direction of arrow 18 such that the reaction chamber 20 between the electrodes always remains of the same size and is thus able to provide flow rates and conversion rates as constant as possible. The polarity of electrodes 12, 16 is alternated at intervals to reduce deposits forming on electrodes 12, 16. Both electrodes 12, 16 serve as sacrificial electrodes as required, whereby deposits usually form on the cathode. After the polarity is changed, the deposits can be removed by the liquid stream. In this case, too, the flow direction is indicated by reference number 14.
(14) FIG. 5 shows a top view of the lower electrode 12 where the upper surfaces 1 and 2, but also the lateral surfaces 4 and 5 can be seen. The tapered lateral regions ought to be no more than 2% of the plane electrode surface.
(15) FIG. 6 shows the upper electrode 16 in a cut-out view which indicates that due to differences in casting, the upper surfaces 1 and 2 on the side opposite surface 10 can have different height levels when surface 10 is plane, such that it is difficult to establish contact via a plate. Therefore, it is preferable according to the invention to make contact for alternating the polarity via a flexible contact strip 22, for example in the form of a link chain, such that every single bar comes in contact with contact strip 22.
(16) In this manner, the secure contacting of all bars can be achieved.
(17) In views (a) and (b), FIG. 7 shows inventive reactors 30, whereby FIG. 7a shows a section through a reactor 20 with a view of electrode 12 according to FIG. 5. Here, the liquid flows via inlet 32 into a pre-chamber 34 and around a bulkhead 36 provided such that the whole stream is directed around bulkhead 36 which serves to equalize the flow. Then the liquid enters reaction chamber 20 between the electrodes 12 and 16. In reaction room 20, the electrodes 12 and 16 are provided in the form of bars laid in alternation. After flowing through reaction chamber 20, the liquid flows through an after-chamber 38, and there again around a bulkhead 40 and through an outlet 42.
(18) FIG. 7b shows a reactor 30 in another sectional plane, without any pre-chamber or after-chamber. Electrodes 12 and 16 constructed of the bars are accommodated in housing 44 which comprises an upper part 48 and a base 46.
