GB1596073A - Scale preventing and descaling device - Google Patents

Description

(54) SCALE PREVENTING AND DESCALING DEVICE (71) We, SALANON S.A., a French corporation of 99, route de Noisy, 93230 Romainville, France. do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a scale preventing an descaling device.

French Patent Specification No. 2,221,407 described a scale preventing device wherein a metal diaphragm, placed inside a processing chamber holding the water to be treated and attached to the pipes to be descaled, is caused to vibrate. Such a device has given practical satisfactory results.

On the other hand, numerous tests have been carried out on devices of the prior art with a view to obtaining such a scale preventing effect by applying an electrical field to flowing water, an electrical voltage being applied to one or a plurality of electrodes immersed in the water flowing in the pipes to be descaled. All the devices to tested have shown the same drawback, i.e., the corroding of electrodes or pipes.

An object of the present invention is to provide an improved descaling device.

The above object as well as others are strained by combining with the device described in the above mentioned French Patent Specification No. 2,221,407 means for generating a pulsating alternating electrical field.

According to the present invention there is provided a processing device to be coupled in a liquid flow line for preventing formation of scale and removing scale foimed in said flow line, said device including a housing having walls defining a treatment chamber and having a liquid inlet and a liquid outlet for connection to said liquid flow line, a flexible diaphragm extending substantially parallel to a wall of said housing in said chamber substantially perpendicular to the liquid flow in sadd chamber, adjacent said liquid inlet, controllable means for causing said diaph- ragm to vibrate, an electrode grid extending through said chamber between said liquid inlet and outlet, and means for applying alternating electric pulses to said electrode grid simultaneously with vibration of said diaphragm.

In fact, tests carried out by the applicant have shown that, by combining a vibrating means and an electrical field generating means, the efficiency of the vibrating means is improved and, by suitably selecuing the voltages applied to the electrical means, the common drawbacks of such an electrical means were eliminated. i.e. especially the corroding effect of electrodes or pipes as well as the dirtying of electrodes.

A further advantage of the present invention is the fact that, while water is flowing from the processing of the present invention, not only no scale settles in the down-stream pipes but also a descaling effect is produced, i.e. the pre-existing scale is carried away from the pipes.

Incidentally, those skilled in the art will understand that a scale preventing device should be distinguished from a descaling one.

By "scale preventing device" one means a device which prevents any water flowing in pipes from fanning a deposit of scale on said pipes. By "descaling device", one means a device which ensures, on one hand that the scale contained in the water does not form a deposit on said pipes, on the other hand, that pre-existing scale on said pipes is removed. One shouls also define the durability of the scale preventing effect produced by a scale preventing device. Indeed, should such a scale preventing or descaling device only operate when water is flowing in the pipes, when no water is flowing during an extended period, a further deposit of scale can occur on the pipes. The durability aorresponds to the time period during which no deposit occurs. Finally, water itself can gain descaling properties, i.e. after treatment in a descaling device it can act, when transferred to pipes which are not connected to the descaling device, as a aause of scale inside said pipes.

So, the vibrating device of the prior art was a scale preventing device, partly descaling, and having a low durability. The device of the present invention is both a scale preventing device and a descaling one. It provides water with high durability and descaling properties as hereafter described.

The invention is described below with reference to the drawings which show preferred embodiments.

Figure 1 shows a first embodiment of the present invention.

Figure 2 shows another embodiment of the present invention.

Figures 3a, 3b and 3c show various waveforms which can be applied to the device shown in Figures 1 and 2; and Figure 4 shows an electrical circuit suitable to feed the device of the present invention.

Figure 1 shows a first embodiment of the present invention Water to be treated flows in a cylindrical chamber 1 from an inlet 2 to an outlet 3. At the end of the chamber opposite to the outlet 3, a flexible diaphragm 4 integral with a metal piece 5 is caused to vibrate by an electro-magnet 6 as known to those skilled in the art. Said chamber is com preied of an electrically conductive grid 11, which is piaced between two insulating rings 12 and 13, made of a material such as a polytetrag#fluoroethylene sold under the trademark "TEFLON". A voltage is applied to the grid by an electrode 14 which is connected to a terminal 15. The electrode 14 is shown as being placed at the center of the grid 11, but it can be connected to any place of said grid.

Figure 2 shows a modified construction of the device of Figure 1, wherein like reference characters designate like or corresponding parts. In this embodiment, the grid 11 extends longitudinally in the cylinder or processing chamber 1, said grid being hold by an insulting material frame 16, 17. Operating the device of the invention requires causing diaphragm 4 to vibrate by applying an alternating field to electro-magnet 6 simultaneously with applying an alternating pulse voltage to grid 13.

Figure 3a, 3b and 3c show examples of alternating, pulse voltage shapes, which can be applied to grid 11 according to the present invention. The various waveforms result from experiments. It should be pointed out that those experiments have shown that applying a voltage whose waveform is a pure sinewave or of a crenellated appearance will produce no substantial effect. On the contrary, by sucessively applying pulses with an alternate polarity, for instance sinewave portions as shown in Figure 3a, or alternate rectangular pulses as shown in Figure 3b, or groups of sequentially alternate pulses as shown in Figure 3c, one can obtain the favourable effects of the present invention As an example, to a device according to the present invention has been applied, on one hand a 50 Hertz frequency in order to energize electro-magnet 6, on the other hand portions of 50 Hertz sinewaves such as shown in Figure 3a having a shape factor lower than 1/2. In such conditions a scale preventing device and a descaling one, as well as a descaling water having a high durability, were obtained. So, during one experiment carried out by the applicant, water processed as mentioned above was taken after treatment and poured into a car radiator. After a few days' use, said radiator was drained into a vessel and after settling the liquid contained in said vessel showed limestone agglomerate sediment, Such results were not obtained from water which had been submitted only to the vibrating effect or which had only been sub mitted to an electrical field. Therefore, some form of synergy takes place between both effects.

Figure 4 shows an embodiment of an electrical circuit adapted to feed the water processing device according to the present invention. This circuit includes a transformer 20 with two secondary windings 21 and 22.

The first secondary winding 21 is connected to the electro-magnet 6. The second secondary winding 22 is connected to a grounding terminal which is linked to the processing chamber housing. The electrode terminal 15 of the processing chamber is connected through a triac 23 to the other terminal of the secondary winding of the transformer 22. The gate of the triac 23 is connected through a diac 24, a fixed resistor 25 and a potentiometer 26 to the terminal 15. Capacitors 27 and 28 are also provided according to the diagram shown in Figure 4. By property adjusting potentiometer 26, a wave form similar to that shown by Figure 3a can be obtained. On the other hand, by parallel putting a capacitor 30 with the processing grid, sinewave modulated pulses can be obtained as shown by Figure 3c.

One will note that, with a water having a pH of 7.5 and a TH hardness of 17, at a temperature of 20 C, the resistance value between terminal 15 of the grid and the ground terminal is in the range of 100 to 700 Ohms.

When the water temperature reaches 900C, this resistance value can drop to 4 to 10 Ohms. In a like manner, when the TH is very high, i.e. when water is vary rich in minerals, said resistance value can drop to as low a value as 1 to 5 Ohms. If pulses having the shape shown in Figure 3a with a 50 volt amplitude are applied, a power as high as 50 watts can be obtained when the apparent resistance at the grid terminal drop.

The foregoing description relates to preferred embodiments of the invention using an electrical grid. Said grid could be replaced by a substantially central electrode or a ring placed concentrically with the pro cessing chamber, in so far as proper eectrioal pulses such as those previously described are applied. From the foregoing it can be realized that this invention can assume various embodiments. Thus, it is to be understood that the invention is not limited to the specific embodiments described herein, but is to be linrited only by the appended claims.

Claims (6)

WHAT WE CLAIM IS: -

1. A processing device to be coupled in a liquid flow line for preventing formation of scale and removing scale formed in said flow line, said device including a housing having walls defining a treatment chamber and having a liquid inlet and a liquid outlet for connection to said liquid flow line, a flexible diaphragm extending substantially parallel to a wall of said housing in said chamber substantially perpendlicular to the liquid flow in said chamber, adjacent said liquid inlet, controllable means for causing said diaph ragin to vibrate, an electrode grid extending through said chamber between said liquid inlet and outlet, and means for applying alternating electric pulses to said electrode grid simultaneously with vibration of said diaphragm.

2. A device as charmed in claim 1 wherein the means for applying alternating electric pulses to said electrode grid is adapted to apply alternating electric pulse groups comprising portions of a sinewave thereto.

3. A device as claimed in claim 1 or claim 2 wherein the means for applying alternating electric pulses to said electrode grid is adapted to apply successive electric pulses with opposite polarities thereto.

4. A device as claimed in any one of claims 2 to 4, wherein said grid extends transversaiy, perpendicularly to the liquid flow in said chamber.

5. A device as claimed in any one of claims 2 to 4, wherein said grid extends longwtudi- nally, parallel to the liquid flow in said chamber.

6. A scale preventing and descaling processing chamber substantially as herein described with reference to Figure 1 or Figure 2, and Figures 3 and 4 of the accompanying drawings.