WO1993018857A1 - Process and device for the regeneration of a water softening resin - Google Patents

Abstract

Process for the regeneration of a water softening resin and resin regenerating devices especially for washing machines. Water softening device comprising a salt reservoir (3) connected on one side to a water inlet (1) and on the other side to a resin container (4) by means of a hydraulic valve (8). The resin container (4) includes an inlet tube for hard water (9) and an evacuating tube (1) for softened water (10) and is characterized in that the volume of brine present in a natural concentration in the salt reservoir (3) and injected into the resin container (4) is less than the volume of brine which the resin container is capable of containing (4). The volume is replenished so that the resin is fully immersed by suppling water from the hard water inlet tube (9) by opening of the latter's hydraulic valve (12) for a given period. Application in all types of machines requiring the use of softened water.

Description

 METHOD AND DEVICE FOR REGENERATING WATER SOFTENING RESIN

This invention relates to a process for regenerating water softening resin and its use devices, in particular for washing machines.

Water softening devices are generally used in dishwashers and sometimes in washing machines in order to remove most of the calcium (limestone) and magnesium contained in machine feed water.

These water softening devices consist of ion exchange resins which have the property of capturing cations, in particular calcium and magnesium ions, which we want to rid the feed water of machines and, to a good degree less, to capture sodium ions.

When all or part of this resin is saturated with calcium and / or magnesium, it loses its softening capacity and must be regenerated. This regeneration is carried out by soaking the resin with a solution, the ions of which will take the place of the calcium and / or magnesium ions of the saturated resin. The solution used can be brine (NaCl solution) because, if the resin is, as mentioned above, less greedy for sodium than calcium or magnesium, the high concentration of brine (and therefore sodium ) around the resin allows sodium to replace calcium and magnesium. This brine is obtained by dissolving salt crystals in water and has a salt concentration of the order of 250 to 300 grams per liter.

On this principle, the methods generally used are of the following type: at a precise moment of the washing cycle, a determined quantity of network water is introduced directly or after a pre-storage-dosing in tanks, in a salt tank consisting of NaCl crystals and supplemented with water which is therefore saturated. This brine solution obtained is thus pushed out of the tank in an amount equivalent to that of the network water introduced into the salt reservoir and will soak the resin jar to regenerate it. This transfer takes place at a predetermined time in the washing cycle using an electrical signal from the machine programmer, which generally actuates an electric valve.

Various improvements to these processes, which have been used for several decades, have focused on optimizing the amount of brine consumed, the shape of the resin pot, on the flows, the distribution, the speed and the circulation of the water to soften and the brine of regeneration in the resin, or on the optimization of chemical exchanges using of the temperature given by the regeneration phase in the washing cycle. All these actions to improve the amount of brine require the development of extremely long and delicate regeneration systems.

The subject of the invention is a process which consists in sending only very little concentrated brine at the time of the regeneration phase. In fact, tests have shown that, while keeping all the other conditions including the volume of brined liquid but with a reduced salt concentration of around 45%, the softening efficiency was comparable. Other conclusive tests were carried out which consisted in optimizing the regeneration function by appreciably increasing the volume but by decreasing by very important factors the concentration. The present invention therefore relates to a process for regenerating water softening resin, characterized in that the resin is immersed for a determined period in brine with a concentration of less than 200 grams of salt per liter, as well as the devices for setting it up. artwork.

The great advantage of using much lower salt concentrations than those used so far is the saving in salt. This leads to having to replenish the salt tank less often, which is easier for the user and better from an ecological point of view. In addition, the devices necessary for implementing the invention are very simple.

The invention will be better understood and other advantages will appear on reading the description which follows, illustrated by the following figures:

FIG. 1 represents a first embodiment of a water softening device according to the present invention,

- And Figure 2 shows a second embodiment of a water softening device according to the present invention. In FIG. 1, the washing water arrives via the conduit 9, passes through the ion exchange resin of the resin pot 4 which largely rids it of its calcium and magnesium ions and is directed towards the tank of the wash (not shown in Figure 1) through line 10. The arrows indicate the direction of the water or brine flow.

The regeneration according to the invention of the resin is carried out in the following manner: the mains water arrives via the pipe 1 directly or after have been stored and dosed in tanks 2, in s salt tank 3. This salt tank 3 is not directly connected to the po: resin 4, but is connected to it by a mixing channel 5. This channel 5 has a fresh water inlet 6 controlled by a hydraulic switch 7. When the resin regeneration operation must be carried out, another hydraulic switch 8 (which can be located anywhere in the mixing channel 5) which controls the entry of brine into the resin pot 4 opens, the network water which arrives through the conduit 1 pushes the brine out of the salt reservoir 3 into the mixing channel 5 and, by the arrival of clear water 6 (l 'switch 7 being open), a supply of clear water in a predetermined quantity dilutes the brine when it passes through the mixing channel 5. Thus, the brine which, initially in the salt tank is saturated (it is "natural concentration" which is a function of the conditions of t temperature and pressure of the device), when it reaches the resin pot 4 is diluted, its final concentration being given by the quantity of clear water to which it has been mixed in channel 5. Thus the concentration of brine used for the regeneration of the ion exchange resin is perfectly controlled. Leaving the salt tank the natural concentration of brine being 250 to 300 grams per liter, the amount of clear water added to it in the mixing channel is calculated to lower the concentration of brine to the value desired.

Obviously, these regeneration operations are automatically controlled during a washing cycle by the programmer, or the presets can be made manually by the user, this operation consisting in the opening of the hydraulic switch 8 controlling the entry of the resin pot 4 and of the hydraulic switch 7 for a determined time. These hydraulic switches can be flaps, valves or gates.

In this nonlimiting embodiment, the water softening circuit has been modified compared to a conventional circuit (addition of a mixer channel 5, distribution and storage of volumes), however, in the case where this circuit does not could be modified, another embodiment of the invention illustrated in FIG. 2, allows the implementation of the invention by simpler modifications of the circuit.

In this FIG. 2, the elements identical or similar to FIG. 1 have kept the same indexing. In the same way as in the previous embodiment, the mains water arrives through the conduit 9, passes through the resin in the pot

4 which removes most of its calcium and magnesium, then is discharged into the machine tank through line 10. The arrows indicate the direction of the water flow.

A conventional brine production device is connected via a conduit 11 and a hydraulic switch 8 to this resin pot 4. The difference with a conventional brine production device is that the volume of brine at concentration natural used, that is to say saturated, is significantly lower, for example 1.5 to 4 times lower. A simple modification of the storage, of the dosages and possibly of the dimensions of the salt reservoir 3 makes it possible to obtain such quantities of brine in natural concentration. When the switch 8 electrically controlled by the programmer is open, the volume of naturally concentrated brine present in the resin pot 4 does not allow total immersion of the resin in the brine. After a time of impregnation of a few tens of seconds to a few minutes of the resin by the brine, mains water is introduced into the resin pot by the conventional filling circuit of the machine symbolized in FIG. 2 by the conduit 9 through a hydraulic intake switch 12 located somewhere in this filling circuit.

This switch 12 remains open for a very short time (of the order of 0.5 to a few seconds depending on its flow rate) sufficient for the volume of water added to allow total immersion of the resin in the brine, the latter having now a larger volume but being much more diluted than initially when it had its natural concentration. Once again, the final concentration of the brine is perfectly under control.

As in the previous embodiment, the hydraulic switches 8 and 9 can be valves, valves or gates. Typically the free water capacity of a resin pot is around 40 centilitres and the resin can effectively soften up to about 30 liters of water for a hardness of 75 degrees hydrotimetric. Regeneration must therefore take place after each passage of 30 liters of softened water. In the prior art, the volume of brine at a natural concentration necessary for such a resin pot and such a hardness is 30 centilitres, the same result can be obtained thanks to the invention for 15 centilitres of brine in natural concentration and 10 to 30 centilitres of clear water added according to one or the other of the proposed devices.

In these two devices, the circulation of water and brine is done by network pressure or by gravity but can also be done by means of pumps. On the other hand, the conduit 1 can be provided in the two devices with a hydraulic switch preventing the rise by diffusion of the salt present in the reservoir 3.

The present invention applies to all types of machines requiring the use of water free of its limescale.

Claims

1. Water softening device comprising a salt reservoir (3) connected on one side to a water inlet (1), and on the other thanks to a hydraulic switch (8) to a resin pot (4) comprising a water inlet pipe to be softened (9) and a softened water discharge pipe (10) characterized in that the volume of naturally concentrated brine contained in the salt tank (3 ) and injected into the resin pot (4) is less than the volume of brine that the resin pot (4) can contain, and that this volume is completed to fully immerse the resin by a supply of water coming from the water inlet (9) to be softened by opening a hydraulic switch (12) of this conduit for a determined period. 2. Water softening device according to claim 1 characterized in that the opening of the hydraulic switch (12) of the water inlet pipe to be softened (9) is controlled by a programmer after opening and closing the hydraulic switch (8). 3. Water softening device according to claims 1 and 2 characterized in that the volume of naturally concentrated brine contained in the salt reservoir (3) and injected into the resin jar (4) is less than order of a factor of 2 to the volume of brine that the resin container (4) can contain. 4. Water softening device according to any one of the preceding claims, characterized in that the hydraulic switches (7,8,12) are valves, valves or gates. 5. Water softening device according to any one of the preceding claims, characterized in that the brine occupying the entire resin pot and in which the resin is immersed, has a concentration of less than 200 grams of salt per liter. 6. Household appliance characterized in that it comprises a device according to any one of the preceding claims.