Electrolytic reactor comprising a cathode and an anode

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, whereby between the inlet and the reaction chamber a pre-chamber is provided in which the inserts are arranged such that the inlet stream is divided by the inserts into two partial streams and directed around the inserts.

Claims

1. 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, characterized in that between the inlet the reaction chamber a pre-chamber is provided in which inserts are arranged such that the inlet stream is divided by the inserts into two partial streams and directed around the inserts.

2. Reactor according to claim 1, characterized in that between the reaction chamber and the outlet an after-chamber is provided in which the inserts are arranged such that the outlet stream is divided into two partial streams by the inserts and directed around the inserts.

3. Reactor according to claim 1, characterized in that the inserts consist of one or more bulkheads.

4. Reactor according to claim 1, characterized in that the inlet and/or the outlet have a circular stream cross-section and the reaction chamber has a rectangular stream cross-section.

5. Reactor according to claim 1, characterized in that the distance between the inserts and the reaction chamber is at least one tenth of the width of the reaction chamber.

6. Reactor according to claim 1, characterized in that die inserts on both sides are wider by at least the length C than an entry cross-section of the reaction chamber.

7. Reactor according to claim 1, characterized in that the stream cross-section of the reaction chamber is much wider than it is high, in particular that the height to with ratio is at least 1:50, preferably at least 1:70 and more preferably at least 1:100.

8. Reactor according to claim 1, characterized in that the reaction chamber has a rectangular cross-section in flow direction and a constant stream cross-section throughout the entire reaction chamber.

9. Reactor according to claim 1, characterized in that the electrode which is on top during operation is movable and that the bottom electrode can be tracked to maintain a constant height (S) of the reaction chamber.

10. Reactor according to claim 1, characterized in that between the housing, preferably between a housing half in the operating state, and the electrode which is at the top in the operating state, a covering is provided which prevents liquid from entering that region.

11. Reactor according to claim 10, characterized in that the covering consists of a flexible material and is arranged such that a movement of the top electrode can be adjusted by a movement thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other advantages and advantageous embodiments of the invention are shown in the figures below where:

[0025] FIG. 1 shows an inventive reactor in sectional view, and

[0026] FIG. 2 shows an inventive reactor in sectional top view.

DETAILED DESCRIPTION

[0027] FIG. 1 shows a reactor 10 with a housing 12 comprising a housing base 14 and a housing top 16. The reactor also comprises an inlet 18 and an outlet 20. The flow direction is marked by an arrow 22. Arranged in the housing, which is closed by the housing top 16, here shown as a lid, are two electrodes 24 and 26, both designed as sacrificial electrodes, and both serving in alteration at different time intervals as anode and as cathode. Both electrodes 24 and 26 consist of a magnesium-containing material and are consumed in the course of the reaction when phosphorus is converted with the phosphate into MAP from the liquid. Between the two electrodes 24 and 26 is a reaction chamber 28 designed as a spacing whereby the length L of the reaction chamber is much greater than the height of spacing S. In particular the spacing height S is also much smaller than the width B of the electrodes, as shown in FIG. 2. In particular, a height/length ratio of 1:150 and a height/width ratio of at least 1:100 is provided. Electrode 26 is movable in the housing and can be tracked to electrode 24 such that the spacing height S always remains constant, even when electrodes 24 and 26 are consumed.

[0028] To equalize the liquid stream in reaction chamber 28, a pre-chamber 30 and an after-chamber 32 are provided, each with an Insert 34, 36. These inserts are bulkheads or dividing walls with the purpose of diverting the liquid entering reactor 10 from Inlet 18 in a plane vertical to the plane of the drawing in FIG. 1, such that the liquid has to flow around dividing walls 34 and 36. In the same manner, an after-chamber 32 is provided in the outlet region in which the liquid is diverted such that it can enter outlet 20 with especially good fluidic properties. This is to accomplish that the stream in the entire reactor 28 is as even as possible and that entering fluid remains in the reaction chamber for about the same time. This improves the transfer from a stream of circular cross-section, as with Inlet 18, to a stream with a flat cross-section, as that of the reaction chamber, and then again to the outlet stream with a circular cross-section.

[0029] In addition, as FIG. 1 shows, a covering 40 is provided on the upper electrode 26 which can be rigidly connected with the housing lid 16 and is attached to the upper electrode 26, for example with a weight 42. If the upper electrode is moved for tracking on account of its consumption, the spacingidentified in FIG. 1 by the letter abecomes larger. Thus, the risk increases that liquid flows across the electrodes instead of through reaction chamber 28. This can be prevented with covering 40, which in particular can be a flexible film, such that the tracking of electrode 26 is possible without a problem.

[0030] FIG. 2 shows reactor 20 in sectional top view. The section plane runs through reaction spacing 28. Liquid which enters in inlet 18 is diverted to the right in the area of pre-chamber 30 and to the left in the direction of the drawing, and flows around a dividing wall 34. This dividing wall 34 is arranged at a distance D before wall 31 that is facing pre-chamber 30. Bulkhead 34 protrudes by at least one length C on both sides beyond the width of reaction chamber 28 in the entry section thereof, whereby width C corresponds to at least width D, with the stream being directed such that the liquid enters the reaction chamber with an even flow geometry distributed across the entire reaction chamber. In the embodiment, the entry cross-section is slightly smaller than width B of the electrodes. It can thus be achieved that for every point in the inlet region there is a defined point in the entry region to reaction chamber 28, and the points can be connected via a partial flow path, whereby the sum of all stream resistances of the partial flow path is always the same.

[0031] If the flow enters the reactor with as even a stream cross-section as possible and as simultaneously as possible, particularly good reaction rates can be achieved in the reactor, andas mentioned abovecrystals can be produced with as even a grain size as possible, which facilitates the later separation and further processing. This measure can be further improved when in the outlet region 20 between reaction chamber 28 and outlet 20 an after-chamber 32 is interposed in which a bulkhead 36 is provided around which the liquid flows such that it can be directed through the outlet with circular cross-section. Preferably, the selected distances D and C should be equal. In the above manner, the throughput rates can be optimized.

[0032] The dividing walls 34, 36 are arranged in the pre-chamber and after-chamber such that when they are installed, the liquid can only flow past them on both sides, but not above or below and through them.