DE3723745C1 - Process and device for breaking emulsions - Google Patents

Abstract

The invention relates to a process for breaking emulsions, in particular oil/water emulsions, by electrolysis, in which, for example, aluminium-containing sacrificial anodes (6) are continuously inserted from the bottom into the emulsion stream flowing through a trough-like cathode (2). This results in the possibility of the active side of the anodes being cleaned, as a result of which a constant current strength and thus constant separation quality are ensured. The invention further relates to a device for carrying out the process, in which the sacrificial anodes (6), passed through the cathode bottom from below, are arranged to be continuously feedable and are simultaneously cleaned on their active surface from the top, for example via a brush device (7). The automatic anode advance is performed continuously by a spindle in combination with a step-down gear and a stepper motor. A particular advantage in this case is further considered to be that the space above the electrolysis region, apart from the scraper device (7) taking up very little space, is free, so that the resulting electrolysis gas can be safely and simply conducted away. <IMAGE>

Description

The invention relates to a method and a direction for separating emulsions, especially oil / water Emulsions according to the preamble of claim 1 or Claim 5.

The in many industrial processes as lubrication, cooling Oils or heat transfer agents are often used in Form of an oil / water emulsion used or come in undesirably associated with water, which is great pro blemishes in disposal.

There are already a wide variety of procedures and one directions for separating emulsions or cleaning polluted water has been developed, but an opti paint, continuous separation under always the same Conditions and always constant quality of the cleaned not allow sufficient water.

So are purely mechanical / physical processes and Facilities known through which be the light oils can be separated peacefully, but the heavy oils cannot be removed satisfactorily from the emulsion. Any emulsifiers that may be present can also be purified mechanical means from the emulsion to be separated be removed.

With the help of purely chemical methods they can be difficult  separable oil / water emulsions with the help of e.g. B. from Alumi nium or iron sulfate and additional flocculants cleaned or separated in a flocculation container. Around The rate of separation can increase with these Additional air can be blown in from below. So-called electrofloatation can also be carried out, where at the bottom of the flocculation tank there is electrolysis is carried out, the ascending electrolysis gases (Hydrogen, oxygen) bring about a faster separation to lead. The separation takes place practically in a closed Container, so discontinuously, so that a conti Nuclear, fully automated working with low Operating costs are not possible.

There are also so-called continuous processes for the separation of Emulsions are known in which by electrolysis flocculation of the impurities is carried out. Doing so for example a relatively continuous stream of verun cleaned liquid to be separated by an electrode area led. The emulsion becomes due to the electrolysis gases foamed and the impurities are flocculated. The use known methods and corresponding facilities each one or more substantially vertical of fed up towards the bottom towards a cathode consuming anode or anodes (sacrificial anodes), for example made of aluminum or aluminum alloys. To always be constant function with constant values or results To maintain the distance between the anode and cathode exactly what is on the forehead side consuming anode, for example from above in a trough-shaped cathode with a flowing emulsion is submerged, is not possible. Because the foam formation in the Electrode area simultaneously promotes the oxidation of the Reaction area of the anode, which means the current flow and thus the electrolysis process will be affected. A  continuous cleaning of the very close to the cathode Reaching active anode area is particularly in one trough-shaped configuration of the cathode is not possible. Also the released electrolysis gas (hydrogen, acid substance) cannot be dissipated safely enough to create an even completely rule out any potential risk of explosion. Because the Arrangement of the anode and its feed mechanism above the Cathode represent an essential handicap for an on capture the released gases just above the electrodes area.

The US-PS 40 48 031 describes a method and an direction for the continuous separation of emulsions or contaminated water, in which a device for the continuous feed of at least one aluminum anode in relation to a cathode is provided to a fixed to maintain a predetermined distance between the anode and cathode hold. The liquid to be separated runs through the electro the area, these previously along the aluminum anode flows, d. H. before going into the space between penetrates the electrodes. Then the flocculent Liquid collected and the so-called floating on top Cake from the cleaned water, which is at the bottom of the separation container is removed.

An unpublished Austrian patent application dung (402/87) proposes a method and a device for Separation of emulsions in which the emulsion in continuous flow, inter alia, by an electro lysis area and partially electrolyzed. The Emulsion is, for example, by mixing in a substance in the material of the sacrificial anode, a desemul gator added, which significantly improves the separation. Here, too, the anode or the anode block is covered with plat from the top into the trough-shaped cathode  introduced, or according to the consumption of the anode on their active side, from above towards the tub floor emotional. It does make a relatively continuous radio tion reached. However, the uniformity of the separation leaves process for the same reasons mentioned above (Irregularity of the electrode gap, contamination of the active anode side, poor electrolysis disposal gases) to be desired. Furthermore, one can always be constant te delivery of the anodes or the anode block during the entire separation process, d. H. in the long run and overall an optimal consistency of the separation process, cannot be optimally ensured.

The object of the invention is a method and a Vorrich device for the separation of emulsions, especially oil / water Emulsions or contaminated water of the type mentioned to indicate which in a problem-free operation or a simple, reliable construction an optimal, constant anode feed with a reliable separation process chen.

This task is accomplished by a process with the characteristics of Claim 1 or by a device with the features of Claim 5 solved.

Accordingly, the inventive method is that the anode from below evenly through the bottom of the trough-shaped cathode in the emulsion stream to be separated is pushed. The automatic anode achieved in this way feed from below through the cathode tub has very large Advantages compared to the known anode feed from above.

As mentioned earlier, the biggest problem is the anode front pushes from above that the anodes ver in the electrolysis area dirty, d. H. an oxide layer is formed, which the  Anode conductivity greatly reduced. Therefore wear the anodes differ. However, according to the invention the anodes passed from below through the cathode, so that the active side of the anode out of the cathode into the emul Sionsstrom protrudes, is a cleaning of the active surface of the Anodes possible from above in a relatively simple manner.

In a further development of the inventive idea, this cleaning can be carried out by a removal mechanism, which for example, a brush mechanism. So there is the possibility of a brushed component in Flow direction of the emulsion over the anode face to arrange the tape as a removal device. The This makes it easy to clean anodes. this has the advantage that the flocculation of the contaminants Foam formation actually desired between anode and catho de, without special arrangement problems of the brush mechanism, is transported into the downstream separation container. There one Always have the same size, clean surface of the anode This is not the case due to foam accumulation is contaminated, causing oxide formation on the reaction Favored area, the electrolysis effect is optimal Way consistent.

Another advantage is that when you run the anode by the cathode from below a fixed Electrode gap can be realized by the steady Anode removal not changed.

In a further development of the inventive concept, the constant Anode spacing can be achieved in particular that under the cathode tub arranged at least one plastic plate is the leadership of the anode or the anode block and electrical insulation and sealing at the same time against emulsion leakage. By order  an O-ring in the cutout of the plastic plate on it, that this ring surrounds the respective anode plate can the management, sealing and keeping the distance of the Anode to the cathode can be optimally realized.

In this solution according to the invention a short circuit is over closed because of the O-ring and the plastic plates at the same time, guiding the anode or the respective anode of the anode block are, therefore, an unwanted, too close approach lead the anode or the anodes to the cathode not possible is.

To carry out the separation even better and more continuously According to the invention, it is also advantageous if the Emulsion flow through into the emulsion stream reaching weir is controlled. This weir can for example a wall reaching into the cathode tub from above be the cathode tub in an inlet basin and in a Electrolysis basin or divided into corresponding areas and an adjustable flow cross section between the wall and Leaves the bottom of the cathode tub. However, the weir can too be a wall standing on the tub floor, over which the Emulsion from the feed area to the electrolysis area crosses. This cross-section can also have a cross-section Can be controlled using a pivoting flap. Here by ensures that given parameters ent optimal fluid throughput is always available is, especially that the anode surface is always sufficient or is optimally rinsed with the emulsion to be separated.

For the inventive device for separating Emul sions, which include an electrolysis unit a trough-shaped cathode and at least one in it has reaching sacrificial anode, it is essential that the at least one sacrificial anode from below through the bottom of the  trough-shaped cathode into the flowing emulsion enough and continuously according to the consumption from below is pushed upwards. Depending on the size of the Electrolysis unit, one or more anodes used who the. A particularly advantageous embodiment is achieved if several plate-shaped anodes in one anode block too be summarized and with the help of at least one under the Insulating guide and you arranged cathode tub tion plate are held or guided. It could be before trains two plastic plates to be provided, then one the plates is a sealing plate, in its cutout or cutouts for the anodes each have an O-ring seal is provided, which acts both sealing and leading. This ensures that the distance of the anode jacket area to the cutout in the bottom of the cathode tub, d. H. the electrode gap or gap is always constant. From this point of view, an opti times constant current underflow are guaranteed. The anodes The feed is not, as usual, perpendicular to that of the anode opposite cathode surface made, but paral lel to this, which makes the electrode gap practical not changed.

The anode distance to the cathode is thus determined by the O-ring Seal specified and can be about 1 to 1.5 mm. Out the anode distance is obtained with the same voltage applied and always constant conductivity of the one to be separated Medium and a constant flow of the medium always constant current density. The electrolysis unit therefore works very evenly, which means that the Alumniniumver need the sacrificial anode and therefore the anode feed exactly can be calculated in advance.

It is advantageous if the anode feed is carried out using a stepper motor also located under the cathode tub,  in conjunction with a reduction gear and one, one very low pitch threaded spindle made becomes. Due to the exact predeterminability of the anode feed there is now the possibility to use the stepper motor continuously Lich, and let it run very slowly, so here is minimized by the consumption of sacrificial anodes.

However, there is also the option of the anode guide to regulate via the current density. Because the electricity drops tight, then this is an indication that the anode is too wide is worn. Other factors leading to the drop in electricity could lead to density, there is in the invention Construction of the electrolysis device is not. Because the anode is constantly cleaned by the brush mechanism; the The conductivity is then at a constant flow of the medium always constant and the applied voltage is also constant.

The degree of tracking of the anodes depends on the medium that is to be separated, or from its conductivity. With help an inductive conductivity probe, which is also equipped with a can be equipped with a very high O-P amplifier Possibility of con. Conductivity over a controlled system keep stant. The salting of the medium to be split can be done via a pulse pump by a PID controller can be controlled. The PID controller gets its impulses from the inductive conductivity probe, which is able Regi actual and target values for the specified controlled system strate. If the current density drops, this is registered; the stepper motor gets a pulse and the anode block will be followed accordingly. When the required The stepper motor receives a stop impulse in terms of current density.

As already mentioned, according to the invention there is the advantageous one Possibility of continuous cleaning of the active Ano  surface from above. By ordering one Scraper device, for example a parallel to the Anode face can be brushing device both the oxide layer with the anode and the electro lysis foam, through which the separation of the emulsion positive is influenced, shot towards a separation container ben. The wiping or cleaning mechanism can be very be designed. So the brush elements on the Outside of a band element, which is parallel to the Ano the front is moved, can be provided. This will saved a lot of space above the cathode tub where through appropriate simple precautions for safe discharge tion of the electrolysis gases can be taken.

Another advantage of the device according to the invention Anode feed from below through the cathode tub is that a very large anode length can be provided. It be there is also the possibility of already existing facilities for the continuous separation of emulsions with the invent retrofit electrolysis unit according to the invention, or the in existing electrolysis unit with Ano the feed from above, by an electrolyte according to the invention unit with anode feed from below to replace. So can be installed in certain separators by installing the electrolysis unit according to the invention one up to 10 times longer anode than usual can be used. Here this ensures a real continuity of the separation process posed.

Due to the inventive design of the leadership of Anodes due to the arrangement of the guide plates directly on the Underside of the cathode trough, so optimally close to the area where the accuracy of the anode guide is directly affects, this leadership does not have to be so long. These high accuracy can also with the guidance according to the invention  can be achieved with relatively thin electrode plates which, when feeding from above, the guides are proportionate would have to be drawn deep into the cathode tub.

The invention will be explained in the following with the aid of an embodiment game of the electrolysis unit according to the invention with reference took explained in more detail on the drawing. It shows:

Fig. 1 shows a schematic longitudinal section through a dung OF INVENTION modern electrolysis unit,

Fig. 2 is a schematic section transverse to the flow of the emulsion, the feed mechanism showing direction,

Fig. 3 shows a detail from the section of FIG. 1, another embodiment of the inlet side of the Katho denwanne, and

Fig. 4 is a schematic representation of a plan view of the cathode pan, with anodes extending into it from below.

As can be seen in particular from FIG. 1, the electrolysis unit according to the invention has as its main component a cathode trough 2 , into which a plate-shaped anode 6 extends with its active end face from below.

From Fig. 3 it can be seen that several anodes 6 are combined to form an anode block, for example via cross members 13 . Below the cathode trough 2 is a plastic made insulating and guide plate 3 and underneath a possibly also made of plastic guide plate 4 is provided, which carries O-rings 5 on their respective passage cutout for the anodes. The respective O-ring 5 lies snugly against the anode 6 , so that a constant electrode gap 14 is ensured between the cutout in the cathode trough for the passage of the anode and the Anodenman.

On one narrow side of the cathode tub 2 , the emulsion to be separated is introduced into the cathode tubs with the aid of an inlet pipe 1 . On this side, a weir 15 can be arranged directly behind the outflow end of the inlet pipe 1 , which divides the cathode trough 2 into an inlet area and an electrolysis area. The emulsion can be dammed up in the feed area, which is guided continuously to the electrolysis area with the help of the weir 15 in a precisely metered manner.

In the exemplary embodiment according to FIG. 1, the weir 15 is a wall that extends into the emulsion stream from above. However, it can also be a wall 16 standing on the tub floor, which creates an overflow weir. The overflow of this weir can be controlled with the aid of a pivotable control flap 17 .

Above the anodes 6 , a removal or brushing device 7 is provided which essentially consists of two drive rollers 8 , via which a belt equipped with brush elements 19 , possibly a toothed belt, is guided. The brush elements 19 streak in the drawing shown Darge drive direction of the rollers 8 in the direction of flow of the emulsion over the anode face.

The medium passed through the cathode trough and through the electrode area or the emulsion to be separated then flows together with the stripped oxide layer and the resulting electrolysis foam into an inlet funnel 9 provided at the outlet end, which in turn opens into a separation container 10 .

In the separation container 10 , the electrolytically separated liquid builds up, the flocculated Ver contaminations collecting on the surface in the form of a so-called cake 11 , while the cleaned water 12 is underneath and is then drawn off.

Fig. 2 shows the parallel arrangement of the anode plates 6 in an anode block, summarized by transverse support 13. It can be seen that the respective guidance of the anodes at their front end through the plate 4 and the O-ring 5 is optimal. The anode feed is carried out via a threaded spindle 20 which is connected to a stepping motor 22 via a reduction gear 21 . The mode of operation of the brush device 7 is also clearly recognizable here. The brush belt 18 guided over the toothed belt roller 8 brushes with its brush elements 19 over the end faces of the anodes 6 or extends with these brush elements 19 into the emulsion flow. As a result, apart from the wiping of the anodes, the flow of the emulsion is also ensured without a flow trough having to be provided at the bottom of the cathode trough.

As can also be seen from FIG. 2, the cathode or the cathode trough 2 and the anode block 6 are connected to a current source 23 .

From Fig. 4 the arrangement of the anodes 6 in the cathode tub 2 can be seen, with the weir 15 the division of the tub in the inlet and the electrolysis area is made light.

Claims (13)

1. Process for the separation of emulsions and contaminated water, in particular oil / water emulsions and heavy metals or heavy metal compounds, by at least partially electrolysis, in which

• at least one sacrificial anode is held in a trough-shaped cathode with its active end face at a predetermined distance from the cathode and is advanced in the direction of the cathode in proportion to its consumption,
• the emulsion flows through the cathode trough and thus the electrolytic area and reaches a separating container arranged thereafter, the contaminants being flocculated by the material removed from the anode,

characterized,

• - That the sacrificial anode ( 6 ) is pushed with its active end face from below through the bottom of the cathode trough ( 2 ) into the emulsions current and between the outer surface of the anode ( 6 ) and the cathode bottom section, a constant electrode gap ( 14 ) is maintained.

2. The method according to claim 1, characterized in that the spent, upper anodes layer and the resulting electrolysis foam with flocculation in the flow direction of the emulsion, essentially the same moderate, is stripped.   3. The method according to claim 2, characterized in that the stripping is carried out from above over a substantially parallel to the anode face brush device ( 7 ). 4. The method according to claim 1, characterized in that the emulsion flow is controlled by a weir ( 15 ) extending into the emulsion stream. 5. A device for separating emulsions for carrying out the method according to claims 1 to 4, the reactor center comprises an electrolysis unit with a continuous flow of the emulsion to be separated, trough-shaped cathode, into which at least one sacrificial anode which is displaceable in relation to the cathode is inserted , characterized in that the sacrificial anode ( 6 ) extends from below through the bottom of the cathode trough ( 2 ) into the emulsion flowing through it and is arranged so that it can be moved continuously from bottom to top. 6. Device according to claim 5, characterized in that a plurality of plate-shaped anodes ( 6 ) are combined to form an anode block and are arranged together via a threaded spindle ( 20 ), a reduction gear ( 21 ) and a stepper motor ( 22 ) continuously from bottom to top . 7. Device according to claim 5, characterized in that below the cathode trough ( 2 ) at least one insulating and at the same time sealing guide plate ( 3 , 4 ) for the anodes ( 6 ) is provided. 8. Device according to claim 7, characterized in that two plastic plates are provided below the cathode trough ( 2 ), an insulating plate ( 3 ) and a sealing and guide plate ( 4 ) in which an O-ring enclosing the respective anode ( 6 ) ( 5 ) is provided. 9. Device according to claim 5, characterized in that above the anodes ( 6 ) a stripping device ( 7 ) is arranged for cleaning the active anode surface. 10. The device according to claim 9, characterized in that the stripping device ( 7 ) is a brush mechanism which enables movement of the brush elements ( 19 ) in the direction of passage of the emulsion. 11. The device according to claim 10, characterized in that the brush mechanism is a with brush elements ( 19 ) and via drive rollers ( 8 ) guided belt which is arranged substantially parallel to the end face of the anodes ( 6 ), running in the flow direction of the emulsion is. 12. Device according to claim 5, characterized in that to keep the guide constant ability of the emulsion an inductive conductivity probe Connection with a high O-P amplifier and a pulse pump is provided.