AU606037B2 - Process and device for treating an aqueous liquid - Google Patents

Description

.7/ AU-AI-6,5705/86 PCT WELTORGANIATbON I E%3EEN k INTERNATIONALE ANMELDUNG VEROFFENTLIGHT NACH DEM VERTRAG OIBER DIE INTERNATIONALE ZUSAMMENARBEIT AUF DEM GEBIET DES PATENTWESENS (PCT) (51) Internationale Patentklassifikation 4 Internationale Verdffcntlichungsnummer: WO 87/ 04422 C02F 1/48 Al (43) Internationales Verboffentl ichu ngsdatu m: 30. Juli 1987 (30.07.87) (21) Internationales /iLktenzeichen: PCT/AT86/00055 I (81) Bestimmungsstaateik: AT (europilisches Patent), AU', (22) Internationales Anmeldedatum: September 1986 (15.09.86) BE (europllisches Patent), CH (europllisches Patent), DE (europltisches Patent), DK, FI, FR (europaisches Patent), GB (europtiisches Patent), IT (europtiisches Patent), JP, LU (europlisches Patent), NL (europilisches Patent), NO, SE (europaisches Patent), US.

(31) Priorituitsaktenzeichen: PCT/AT86/00007 (32) PrioritiFntum: 21, Januar 1986 (21,01.86) Verdffentlicht Mil internationalern Rechier~jwnbericht.

(33) Prioritlitsland: AT Mit gednderen AnsprncI: A .'CTION 34(4)(a) DIRECTION SEE F01-0-1 NAME DIRECTED Ma~ 4 q~r3.61U ac.r'6 C-4K cT~V *34, fl-610O 1rt0cA~, EP 1987 3;AbnrVt acers (A (74) Anwilte: SONN, Helmut usw,, Riemnergasse 14, A-1010 Wien (AT).

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AUSTRALIAN

14 AUG 1987 PAT OF lc~ (54) Title: PROCESS AND DEVICE FOR TREATING AN AQUEOUS LIQUID TUNG ZUR DURCHFOH-RUNG DES VERFAH-RENS (57) Abstract According to the process used in particular for r.-moving scale and corrosion, and to prevent the formation of scale and corrosion in vessels and pipelines through which the liquid to be handled passes, the liquid is fed during treatment, through a treatment chamber on theside of which is arranged an electrode which is electrically insulated from the liquid. A high-voltage source is connected via a high-voltage terminal with the electrode and tht, other terminal (10) isconnected electrically with the liquid.

(57) Zusammenfassung 'Verfahren und Vorrichtung zur flehandlung einer wv~sserigen Flflssigkeit, insbesondere zur Beseltigung von Kesselstein und Korro- 1sion und zur Verhtltung der lBildung von Kesseistein und Korrosion in GeftI4en und Rohrleiwungen. die von der behandelten Fltlssigkeit durchflossen werden, B~el d-.r Behandlung wird die Fl~ssigkcit durch einen Behandlungsraum gelielt, an dessen Seite mindestens eine Elektro- 1 de angiordnet list, die von der FIlssigkeit elektrisch Isoliert ist. Einc l-ochspannungsquelle ist mit elnem HochspannungsanschluA mit der Elektrode und mit dem anderen Hochspannungsanschlu4 mit der FliIssigkeit elektrisch leitend verbunden.

FLOSSIGKEIT UNI) VORRICH- MUZ I KMLI ALLUWEs s.

HRF/3459F If Procedure for the treatment of an aqueous liquid and a device for executing the procedure The invention relates to a procedure for the treatment of an aqueous liquid, whereby this liquid is subjected during circulation between two opposing electrodes, separated from the liquid by means of insulation material, to the effect of an electrical field formed by connecting these electrodes to a dc-high-voltage potential, particularly for the removal of boiler scale and corrosion, or for the prevention of the formation of boiler scale and/or corrosion in the containers or pipe systems through ahich the treated liquid flows. In add:ti.ton, the invention relates to a device for the execution of this procedure with a treatment chamber having an inlet and outlet and with two electrodes, arranged opposite each other on either side of the treatment chamber and electrically insulated from the treatment chamber, as well as with an electrical dc-high-voltage sourse connected to the electrodes.

Because of substances of various kinds that are contained in the water, particularly lime dissolved in water, boiler scale and corrosion are caused in containers and pipes in which water is exposed to physical effects, such as intensive heating in hotwater boilers and steam kettles. It is known that countermeasures can be taken against the unwanted precipitation of substances contained in the water which result in boiler scale, and against the formation of corrosive properties of the water by 1 7-e a: IMt UUMMiSSIONER OF PATENTS

AUSTRALIA

SBR:eah 109M it== 11 subjecting the water, before it reaches the containers or pipes in which it is exposed to special conditions, to the effect of an electrical and/or magnetic field. By this means it is possible to reduce, to a greater or lesser extent, the tendency for the development of corrosive properties of the water, and it is also possible to reduce again the extent of boiler-scale formation and corrosion, produced in containers or pipes by supplying them with untreated water, by supplying these containers or pipes with the water treated as cited above; the extent of the effect of the treatment of water or aqueous liquids with magnetic and/or electrical fields depends also significantly on the intensity of the physical conditions acting on the water of the aqueous liquid after such a preliminary treatment; thus, for example, the effect that can be achieved with techniques that have become known up to know drops the more, the higher the thermal load to which the pretreated water is subjected. Various known devices have only a slight effect and very often these devices have a relatively costly construction and require constant and costly maintenance, and for this reason alone are scarcely suitable for general use.

Many of these devices require that a special prefilter be installed ahead of them, and this results in additional procurement and maintenance costs.

From GB-A 1 274 902 a device of the above cited type is known, in which the two electrodes, separated from the liquid by insulating material, are connected to the two opposing polarity carrying 2 z3r I riii clamps of a dc-voltage source. For this purpose, this GB-A also mentions the possibility, to separate only one of the two electrodes of such a device from the liquid by means of insulating material. A preferred embodiment of the device cited in GB-A 1 274 902 has several sequentially arranged treatment units, each with two electrodes, separated from the liquid by insulating material, whereby two dc-voltage fed treatment units are followed by one fed with ac-voltage.

From US-A 4 073 712 a device for the electrostatic treatment of water is known, in which the liquid to be treated is led through the annular gap formed between two coaxially -arranged cylindrical electrodes, whereby both electrodes are separated from the liquid by means of insulating material and connected to the two clamps with opposing polarity of a dc-voltage source.

In addition, a device is known from BE-A 465 481 in which a liquid in flow-through is exposed to the effect of an electrical alternating field. In this embodiment of this device the liquid flows through a glass tube, on the outside of which, thus separated from the liquid, an electrode is arranged which is connected, as is an electrode located coaxially inside the tube within the liquid, to an ac-voltage source.

S7 J It is the task of the present invention to create a process and a device of the type described in the introduction, with which it is possible to achieve a better effect than it is possible with the known technologies of the type discussed herein, and which can be realized in a simple manner at lower cost.

The process according to the invention of the type discussed in the beginning, is characterized by the fact that the liquid to be treated is subjected to an electrical field effect formed by a dc-high-voltage potential with one pole on the two cited opposing electrodes, which are insulated from the liquid, and with the other pole electrically conducting on the 'liquid. With this process it is well possible to respond to the above cited goal.

It can be assumed that the advantageous properties of the procedure according to the invention are due to the fact that the water or aqueous liquid sustain a change in the area of the surface layer flowing along the insulation of the electrode or the electrodes, which strongly counteracts the precipitation of substances contained in the liquid and the creation of corrosive properties in the liquid. In this context it can be stated that aqueous liquids respond to the described field effect because water molecules are themselves dipoles and the substances contained in the water (either dissolved or not dissolved) are present in the form of positive or negative ions and can thus be oriented in accordance with the polarity. Thus, during the preparation of boiling water with rod-type heating elements, in 4 <j .I 'P 3 L practical tests the deposits that result when water with a high lime content is heated could be reduced by pretreatment of the water at a quantity determined for the preparation of boiling water to one-quarter compared to the use of water that was untreated; in addition to this, when water pretreated by the process according to the present invention was used, this brought the added effect that the quantity of deposits that occurred on the ro-type heater elements during the preparation of boiling water did not exceed a specific limiting value even after a longer period of operation. It was also possible to establish the fact that deposits or boiler scale that had formed previously when untreated water was used for the preparation of boiling water were clearly diminished during the subsequent use of water that had previously been treated with the process according to the present invention. It seemed that, for the achievable effect it is not so much the absolute value of the dc-high-voltage used which is the influence, but much rather the electrical field strength present in the liquid which also forms an electrode layer on the electrodes or in the insulation of it, and, in connection with it, the load densities occurring in the liquid, as well as the electrode surface. The respective distance between these electrodes is also of importance.

In addition, it is preferred, for the greatest possible holding back of the precipitation of substances contained in the liquid that the liquid is held in the area of the electrodes, on a negative potential relative to the electrode(s). However, it is also possible to keep the liquid in the area of the electrodes on a positive potential relative to the electrode(s) and thus counteract the intrusion of liquid particles or substances contained in the liquid into the insulation covering the electrode.

The effect of the treatment of the liquid by means of the procedure according to the invention can still be considerably improved if the liquid is subjected in the area of the electrodes to a flow direction change of approximately 1800.

The device according to the invention of the type cited in the beginning is characterized by the fact that the two opposing electrodes are electrically connected and one of the connections of the electrical dc-high-vol%-age source is connected to the two electrodes and the other connection of the electrical dc-highvoltage source with a contact electrode forming the electrically conducting connection to the liquid. This device can provide a very good treatment effect with very simple construction and relatively little high-voltage. A d.c. current source is preferably used as high-voltage source. It is hereby a further advantage if the positive connection of the high-voltage source is connected to the electrically insulated electrodes and the negative connection of the high-voltage source to the contact 6 Ii

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electrode forming the electrically conducting connection to the liquid.

In a simple manner a suitable form for the treatment of the liquid of liquid surface flowing along the electrodes can be attained if it is provided that one each of the two electrodes, connected in an electrically conducting manner is arranged on a flat side of a treatment chamber constructed as a flat box. The processing effect achieved with the device can be further improved, in a simple manner, if it is planned that the flowthrough path in the treatment chamber is formed by a U-shaped bridge and the openings for the inflow and outflow of the liquid are adjoining to each other, on either side of the bridge. With regard to the constructive arrangement of the treatment chamber of the device and the arrangement of the insulated electrodes used for the treatment of the liquid flowing through the treatment chamber, which form, electrically seen, condenser plates, it is of particular advantage if the can is formed from two can halves made from synthetic material, into the flat wall sides of which the insulated electrodes are embedded and which are arranged between and compressed by two clamping plates made of metal. The individual components of the device according to the invention can be produced in a simple manner and good protection of the insulated electrodes, electrically as well as mechanically, is assured; the electrodes are also well protected against chemical effects. It is also possible, should it prove necessary or 7 0

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1' desirable at some time, to easily perform maintenanca and cleaning of the device, due to the construction of the can from two can halves of synthetic material, which permit a simple dismantling of the device. However, it should be pointed out that the device according to the invention is practically maintenance-free. Due to the two clamping plates a mechanically very stable construction is attained which also provides for a high pressure resistance of the can, and it is also possible to attain by means of these clamping plates, to have not only good mechanical protection of the can which forms the treatment chamber, but also an effective electrical shield, which is a security advantage.

The treatment of aqueous liquids with the process according to the present invention and with the device according to the invention is not only significant with regard to avoiding the precipitation of substances contained in the water and deferring the appearance of corrosion phenomena in the containers or in the pipe system through which the liquid flows, and for the subsequent reduction of boiler scale and corrosion damage that has already occurred; the changes in the properties themselves can be used in various other areas. As an example, the treatment according to the invention makes it possible to condition the water in swimming pools by using a smaller quantity of chemical additives than has been the case up to now; thus, it is possible to achieve a specific disinfection effect with a smaller quantity of added 8

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chlorine than it is possible with untreated water, and one can correct the ph-value of the water in a swimming pool by the addition of a smaller quantity of ph- of ph additives.

It is stated most emphatically that during the process according to the invention there is practically no electrical current between the liquid that is connected electrically to a highvoltage potential relative to the insulated electrodes and the electrically insulated electrodes; there may possibly be a negligible leakage current that is extremely small through the finite insulation resistance to the insulating material that covers the electrodes.

In the process according to the invention, the treatment effect is substantially influenced by the field strength and by the charge density on the surface layer of the liquid to be treated that is facing the insulated electrode.

The invention is described in greater detail below on the bases of examples that are shown in the drawings. The drawings show: Figure 1: A first embodiment of a device according to the invention in a plan view; Figure 2: This embodiment in cross-section on the line II-II in Figure 1; and 9

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1* Figure 3: This embodiment in cross-section on the line III-III in Figure. 1; Figure 4: shows the circuit of a high-voltage source provided for the device according to the invention, and Figures 5 and 6 show another embodiment in two cross-sections, with Figure 5 is a cross-section along line V-V in Figure 6 and Figure 6 a cross-section along line VI-VI in Figure The embodiment of a device according to the invention shown in Figures 1 to 3 has a treatment chamber 1 through which the liquid to be treated is flowing. Inlet and outlet openings 2, 3 are provided for the inflow and outflow of the liquid to be treated.

The direction of flow can be in either direction. On both sides of the treatment chamber 1 two electrodes 4, 5 are arranged which are electrically insulated from the treatment chamber 1.

Electrodes 4, 5 are connected in an electrically conducting manner by means of line 6. One connection 7 of an electrical high-voltage source 8 is connected to the electrodes 4, 5. The high-voltage source 8 is provided with electrical energy through its clamps 9, from an electrical supply network. The other high-voltage connection 10 of the high-voltage source 8 is connected to a contact electrode 11, which forms an electrical connection to the aqueous liquid within the treatment chamber 1.

The contact electrode 11 can, as shown in the case illustrated by Figures 1 to 3, an own electrode arranged in the treatment k hRA a- <'2 i I-

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i chamber 1; this contact electrode may, however, also be formed by another metallically conducting part, in contact with the liquid flowing through the treatment chamber 1, such as by metal pipes, which lead to the inflow or outflow opening of the device.

The high-voltage source 8 can be in the form of a condenserrectifier-cascade circuit, as is shown in Figure 4. However, other configurations of high-voltage sources can be considered, so-called combinatorial circuits with high-voltage output, and, if desired, the high-voltage source can be provided with a separation transformer for the galvanic separation of the power supply. If necessary, the high-voltage source can also by an a.c. source. If necessary, the high-voltage source can also be an ac-voltage source.

The treatment chamber 1 is in the form of a flat can, consisting of two can halves 14, 15 of synthetic material. The electrodes 4, 5 are embedded into the flat wall sides 16, 17 of the can halves 14, 15. The can halves 14, 15 are arranged between two clamping plates 18, 20 made of metal, which, in turn, are held together by clamping screws 21. By means of the clamping plates 18, 20, the can halves 14, 15 are pressed together, whereby a sealing ring 22 is inserted between the facing rims of the can halves 14, 1-1 L -1 Ii a Within the treatment chamber 1 a bridge 23 is provided by ribs molded onto the can halves 14, 15, by means of which a U-shaped flow path through the treatment chamber is formed, which is indicated in Figure 1 by an arrow 24 and leads from the inflow to the outflow opening. These openings 2, 3 are adjoining to each other, arranged on either side of the bridge 23.

In practically arranged devices which were used for the treatment of water for the purpose of preventing the formation of boiler scale or the removal of boiler scale, a high-voltage between and 6 kV, preferably a high-voltage of 5 kV was used. The walls 16 separating the electrodes 4, 5 from the water in the treatment chamber 1 had a thickness of 3 mm.

In the embodiment of a device according to the invention, the treatment chamber 1 has an elongated shape and is constructed as cavity of a synthetic material container 26, in the walls 27, 28 of which the electrodes 4, 5 are embedded. Analogous to the embodiment according to Figures 1 to 3, the electrodes 4, 5 are electrically connected by a line 6 and are located on one highvoltage contact 7 of a high-voltage source 8; the other high voltage contact 10 of the high-voltage source 8 is located on a metallic feed tube, through which the liquid flows into the treatment room 1. In this case too, the high-voltage source 8 can be constructed in various forms, as this has been discussed above.

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Claims (10)

1. A process for the treatment of an aqueous liquid, for the prevention of formation of boiler scale and/or corrosion in containers or pipe systems through which the treated liquid flows, comprising subjecting the liquid to be treated to an electrical field effect formed by connecting a dc-high-voltage potential to two essentially flat, electrically connected opposed electrodes, between which the liquid flows, the electrodes being insulated from the liquid, with one pole of the potential being connected to the two electrodes, and with the other pole being electrically connected to the liquid.

2. A process according to claim 1, wherein the liquid is held, in the region of the electrodes, to a negative potential relative to the electrode(s).

3. A process according to either claim 1 or claim 2, wherein the liquid is subjected, in the region of the electrodes, to an approximately e• 180 change of flow direction.

4. A device for carrying out the process according to any one of claims 1 to 3 comprising a substantially planar treatment chamber provided with an inflow opening and an outflow opening, two substantially flat, electrodes arranged on opposite sides of, and electrically insulated from, the treatment chamber, and an electrical dc-high-voltage source, one pole of which is connected to the two electrodes, wherein the two electrodes are electrically connected to each other, and the other pole of the electrical dc-high-voltage source is connected to a contact electrode establishing an 25 electrically conducting connection to the liquid.

5. A device according to claim 4, wherein the positive contact of the high-voltage source is connected to the electrically insulated electrode(s) and the negative contact of the high-voltage source is connected to the contact electrode establishing the electrically conducting 30 contact to the liquid.

6. A devIce according to either claim 4 or claim 5, wherein the two electrodes are arranged each on a flat side of the treatment chamber which is shaped in the form of a flat can whereby the flow path of the fluid between the electrodes is substantially planar. 5556 S S. S' SS*S S 6 .5 5 S -13- HRF/0344r

7. A device according to claim 6, wherein a U-shaped flow path is formed in the treatment chamber by means of a bridge and the openings for the inflow and outflow of the liquid are arranged adjoining each other on either side of the bridge.

8. A device according to either claim 6 or claim 7, wherein the flat can is formed out of two can halves made from synthetic material, in the flat wall sides of which the insulated electrodes are embedded and which is arranged between two clamping plates made of metal and compressed by the same.

9. A device according to any one of the claims 4 to 8, wherein the contact electrode which provides the electrically conducting connection to the liquid, is a metal tube which leads to the inflow or outflow opening of the device.

10. A device substantially as hereinbefore described with reference 15 to Figures 1 to 4 or 5 and 6 of the drawings. S11. A process for the treatment of an aqueous liquid substantially as hereinbefore described with reference to the drawings. DATED this TWENTY FOURTH day of APRIL 1990 Maitron Geratebau Ges.M.B.H. Co. KG Patent Attorneys for the Applicant SPRUSON FERGUSON 0 -14-