Reactor Having a Sacrificial Anode

Abstract

A reactor is proposed that comprises a cathode and a sacrificial anode, in which a spacing between cathode and anode is kept constant by the cathode following, or tracking, the anode.

Claims

1. A reactor comprising a housing (1, 4), a cathode (3), and an anode (2), wherein the cathode (3) and the anode (2) delimit a channel (10), the cathode (3) being movable in the housing (4) relative to the anode (2).

2. A reactor as in claim 1, wherein the anode is a sacrificial anode and a spacing (S) is included between surfaces (25, 27) of the anode (2) and the cathode (3) delimiting the channel (10), independent of consumption of the anode (2).

3. A reactor as in claim 1, wherein at least one electrically nonconductive spacer (9) is disposed between surfaces (25, 27) of the anode (2) and the cathode (3) that delimit the channel (10).

4. A reactor as in claim 3, wherein the spacing (S) is kept constant with the help of gravity, one or more springs, or one or more actuators.

5. A reactor as in claim 2, wherein the surfaces (25, 27) of the anode (2) and the cathode (3) that delimit the channel (10) are planar.

6. A reactor as in claim 2, wherein at least one of the anode (2) and the cathode (3) is rectangular.

7. A reactor as in claim 1, wherein the housing includes an upper part and a lower part, and wherein the lower part (1) serves as a transport container for the anode (2).

8. A reactor as in claim 7, wherein outer measurements (L, B) of the lower part correspond to the measurements of a standardized transport system.

9. A reactor as in claim 1, wherein a surface (27) of the cathode (3) that delimits the channel (10) or a surface (25) of the anode (2) that delimits the channel (10) has a plurality of flushing nozzles (12).

10. A reactor as in claim 9, wherein the cathode (3) has a distribution chamber (11), and the flushing nozzles (12) are hydraulically linked to the distribution chamber (11).

11. A reactor as in claim 1, further including means (7) for detection of the position of the anode (2) and/or the cathode (3).

12. A reactor as in claim 1, further including means for detection of electrical current (I) that flows between the anode (2) and the cathode (3), or electrical voltage (U) that is applied between the anode (2) and the cathode (3).

13. A reactor as in claim 1, wherein the anode (2) is a sacrificial anode and comprises a magnesium-containing material.

14. A reactor as in claim 1, wherein a liquid containing phosphate salts flows through the channel, and phosphate salts are removed at the anode.

15. A reactor as in claim 3, wherein the surfaces (25, 27) of the anode (2) and the cathode (3) that delimit the channel (10) are planar.

16. A reactor as in claim 5, wherein at least one of the anode (2) and the cathode (3) is rectangular.

17. A reactor as in claim 2, wherein a surface (27) of the cathode (3) that delimits the channel (10) or a surface (25) of the anode (2) that delimits the channel (10) has a plurality of flushing nozzles (12).

18. A reactor as in claim 3, wherein a surface (27) of the cathode (3) that delimits the channel (10) or a surface (25) of the anode (2) that delimits the channel (10) has a plurality of flushing nozzles (12).

19. A reactor as in claim 5, wherein a surface (27) of the cathode (3) that delimits the channel (10) or a surface (25) of the anode (2) that delimits the channel (10) has a plurality of flushing nozzles (12).

20. A reactor as in claim 2, further including means for detection of electrical current (I) that flows between the anode (2) and the cathode (3), or electrical voltage (U) that is applied between the anode (2) and the cathode (3).

Description

DRAWINGS

[0017] Here:

[0018] FIG. 1 shows a lengthwise section through an embodiment example of a reactor according to the invention.

[0019] FIGS. 2A, 2B and 2C show three different states of the sacrificial anode.

[0020] FIG. 3 shows a plurality of reactors connected in series and in parallel.

DESCRIPTION OF THE EMBODIMENT EXAMPLE

[0021] In this embodiment example, the reactor according to the invention consists of a two-part housing with a lower part 1 and an upper part 4. The housing can be separated along a horizontal separation plane in FIG. 1. The contact surface between the lower part 1 and the upper part 4 is indicated with the reference number 21. The separation plane also lies there.

[0022] A circumferential seal 23, which can be made, for example, as an O-ring, is disposed in the region of the contact surface 21 so that the liquid inside the housing does not get into the environment.

[0023] In order to be able to seal the upper part 4 tightly to the lower part 1 of the reactor, there are additionally closures 8 arranged in the region of the contact surface. By opening the closures 8, the upper part 4 can be separated from the lower part very quickly and with low personnel cost.

[0024] In this embodiment example, the lower part 1 accommodates a sacrificial anode 2, which consists of a magnesium-containing material, if the reactor is used, for example, for recovery of phosphate salts from a liquid. One such process is described in the applicant's DE 10 2010 050 691 B3. Using the reactor according to the invention, it is possible, by applying a low electrical DC voltage, to supply magnesium ions to the phosphate- and ammonium-containing liquid and to split the water contained in the liquid into OH.sup. and H.sup.+ ions, so that the pH becomes elevated and the reactions needed for precipitation can take place. Through the low energy demand and the omission of the feed of an alkali to raise the pH value, the costs for operating the system are lower than in the process known from the prior art. A pH of about 9 is desirable for the desired precipitation.

[0025] Since hydrogen builds up in the operation of the reactor, in the upper part 4, there is a connection 28 through which the hydrogen can be drawn off and sent to another use.

[0026] Of course, the anode 2 can also consist of a different material if the process in the reactor according to the invention requires it.

[0027] The anode 2 is made as a rectangular plate having a certain thickness; therefore, it is, if all three dimensions are considered, cubical. Frequently, the anode 2 consists of a magnesium-containing material, which must be transported safely and without damage.

[0028] This is why provision is made according to the invention to use the lower part 1 at the same time as a reusable transport container for the anode 2. In order to optimize the transport of the lower parts 1, the lower parts 1 preferably have the dimensions of a Euro pallet or another standardized transport container. It is especially preferable if the empty lower parts 1 can be nested. In this way, the transport of the anode 2 from the manufacturer of anode 2 to the user and of the empty lower parts from the user to the manufacturer becomes optimized.

[0029] A cathode 3, which as a rule is made of stainless steel, is disposed above the anode 2. The cathode 3 is accommodated in the upper part 4 of the housing so as to be guided in it, such that the cathode 3 moves in the direction of the anode 2 under the effect of gravity.

[0030] To keep the cathode 3 from lying directly on the anode 2, spacers 9 are arranged between the anode 2 and the cathode 3. The distance between the surface 25 of the anode 2 and the surface 27 of the cathode 3, which delimit a channel 10, is called the spacing S. A liquid that is being treated in the reactor flows through the channel 10. The spacing S is an important parameter for optimizing the functioning and/or the energy consumption of the reactor. This is why it is very advantageous that the spacing S can be established simply and precisely in correspondence with the requirements of the specific case by means of the spacers 9.

[0031] The lateral boundaries (side walls) of channel 10 are not visible in the lengthwise section in FIG. 1. The side walls of the channel 10, which is rectangular in cross section, are formed by the lower part 1 and the upper part 4 of the housing.

[0032] In this embodiment example, the surfaces 25 and 27 delimiting the channel 10 are planar. Thus it is extremely simple to keep the spacing S between anode 2 and cathode 3 constant, independent of the consumption of the anode 2.

[0033] The upper part of the housing 4 has an inlet 5 and an outlet 6. The liquid to be treated in the reactor is supplied via the inlet 5 and then flows through the channel 10, which is rectangular in cross section, between the anode 2 and the cathode 3 to the outlet 6. The transition regions 31 between the inlet 5 and the channel 10 and between the channel 10 and the outlet 6 are dimensioned very generously.

[0034] Of course, it is also possible to provide the inlet 5 and the outlet 6 in the lower part of the housing 1 [sic; lower part 1 of the housing]. Combinations are also possible. If the lower parts 1 are used as transport containers, it is advantageous if there are no connections in the lower part 1, since this simplifies the exchange of lower parts 1 and the anodes 2 in them.

[0035] In the operation of the reactor, deposits can form on the surfaces 25 and 27 of channel 10, which will impede the liquid treatment process or even make it impossible. To be able to remove such deposits during the operation of the reactor, a distribution chamber 11 and a plurality of flushing nozzles 12 are made in the cathode 3. The distribution chamber 11 is supplied with a cleaning liquid as necessary via a connection, which is not shown. The cleaning liquid is pumped into the distribution chamber 11 at sufficient pressure and in a sufficient amount and flows through the flushing nozzles 12 into channel 10. Through the number of flushing nozzles 12 and their arrangement and design, in combination with the pressure of the flushing liquid in the distribution chamber 11, it is possible to remove even stubborn deposits on the surface 25 of anode 2, as well as on surface 27 of cathode 3.

[0036] The liquid that is to be treated in the reactor can be used as the flushing liquid. In this case, the flushing effect is ultimately achieved through the kinetic energy with which the flushing liquid flows through the flushing nozzles 12 and strikes surface 25. Through the deflection of the flushing liquid at surface 25, the flushing liquid also reaches surface 27 and cleans it.

[0037] However, it is also possible to use a flushing liquid containing cleaning additives or chemically active substances.

[0038] The anode 2 is electrically contacted, for example, via an electrical contact 14. Correspondingly, cathode 3 is contacted via an electrical contact 15. The electrical connections and the voltage source that supplies the anode 2 and cathode 3 with electric power are not shown in FIG. 1.

[0039] As already noted, cathode 3 can drop downward under the force of gravity. This means that with increasing consumption of the anode 2, the cathode 3 will continue to fall farther downward in the direction of the lower housing part 1.

[0040] The invention makes use of this effect in that the position of the cathode 3 relative to the upper part 4 of the housing is used as an indicator for the consumption of anode 2. This relationship is explained in more detail by means of FIGS. 2A, 2B and 2C. In each case, means for registering the position of the cathode (also called position sensor 7 below) are arranged on the upper part 4 of the housing. Said position sensor can be a commercially available position sensor.

[0041] The relationship between the consumption of the sacrificial anode 2 and the position of the cathode 3 relative to the upper part 4 of the housing is illustrated in three stages in FIGS. 2A-2C.

[0042] In FIG. 2A, the situation is presented as in FIG. 1. The sacrificial anode 2 is unused. Consequently, the cathode 3 has taken its highest point in the upper part 4 of the housing. Now, when the thickness of the sacrificial anode 2 decreases due to the continuous operation of the reactor, cathode 3 sinks farther downward and consequently a pin 29 of the position sensor 7 moves downward relative to the upper part 4 of the housing. This situation is shown in FIG. 2B. At this point, the sacrificial anode 2 still has only about half the thickness of the unused state. The position of cathode 3 can be measured from the relative movement of the pin 29 relative to the upper part 4 of the housing and, due to the spacer 9, the thickness of the sacrificial anode 2 can also be determined.

[0043] In FIG. 2B, it can easily be seen that the channel 10, which is delimited by the surfaces 25 and 27, likewise moves downward with increasing consumption of anode 2. Consequently, transition regions 31 made in the lower part 1 of the housing both at the inlet 5 and at the outlet 6 must be sufficiently long, mainly in the vertical direction. This ensures that the treated liquid gets into channel 10 and from there reaches outlet 6 independent of the thickness of anode 2.

[0044] FIG. 2C shows the state in which the anode 2 has been completely consumed. In this state, the spacers 9 lie directly on the lower part 1 of housing 1 [sic]. Of course, current can no longer flow through the cathode 3. Thus, the complete consumption of anode 2 can also be detected through this decrease of the current to zero. Of course, it is also possible to detect the complete consumption of anode 2 by detecting the position of the output signal of the position sensor 7.

[0045] According to the invention, it is possible to operate a plurality of reactors according to the invention in series and/or in parallel. This arrangement is shown schematically in FIG. 3.

[0046] It is possible here that, in each case according to the consumption of anode 2, not all of the reactors will be supplied with electric voltage. Rather, there is the possibility of providing only a part of the reactors with electric power in correspondence with the amount of accruing liquid that must be treated.

[0047] When a plurality of parallel lines of reactors are present, it is also possible to hydraulically uncouple a reactor or a line of reactors from the system and then to replace at least one anode in the reactor or idle line. The operation, or the treatment of the liquid, can then be continued in the parallel connected reactors or lines of reactors without interruption.

[0048] In FIG. 3, the reference numbers mean:

[0049] 119 Inlet

[0050] 120 Outlet

[0051] 121 Sensor for measurement of phosphate content in outflow

[0052] 122 Control

[0053] 123 Power supply of a reactor

[0054] 124 Output signal of position sensor 7

[0055] 125 Output signal of sensor 121

[0056] 126 Control signal of control 122 for the performance (voltage U and/or current I) of a power supply 123

[0057] 127 Output performance of a power supply 123

[0058] It becomes clear from this presentation that the performance of the overall system is scalable in a very wide range by connecting and disconnecting individual reactors or lines and, because of the redundancy of the parallel and series connected reactors, the overall system can be operated very reliably.