FR2690913A1 - Continuous ion exchange with regeneration - comprises two resin columns functioning alternately with operational times controlled by hardness monitor - Google Patents

Abstract

Continuous softening of water by ion exchange, with regeneration, in two stages. (a) At least part of active resin (A) softens water for time (ta) whilst second part of partially saturated resin (B) is regenerated for a time (tr). (b) At end of this period (ta), resin (B) is active for a period (tb) whilst resin (A) is regenerated for a period (tr). The regeneration period (tr) is equal to or less than softening time (ta, tb). Installation comprises: (a) independent containers (A, B) of ion exchange resin, (b) regeneration system (2), (c) softening circuit (16, 73, 74, 24), (d) regeneration circuit (14, 17-21, C1, 83, 84, 23), (e) link matrix (3, 4) allowing each container (A, B) to be connected to either softening or regeneration circuit, (f) control unit. USE/ADVANTAGE - Steam generators (claimed). Low cost continuous automatic operation.

Description

CONTINUOUS WATER SOFTENING PROCESS, INSTALLATION FOR ITS IMPLEMENTATION
IMPLEMENTATION AND APPLICATION OF THE SAME INSTALLATION TO GENERATORS
STEAM
The present invention relates to a continuous water softening process, using ion exchange resin, as well as to an installation capable of being used for carrying out the process.

 The field of the invention is that of the treatment of water intended for use in installations where it undergoes temperature rises, such as steam generators, water injectors in hot ovens, condensers or boilers.

 These waters naturally loaded with dissolved salts, in particular calcium and magnesium, are the source of a thorny problem of accumulation of limestone and tartar, as a result of evaporation, in the various organs of the installations mentioned above. .

 It is easy to imagine the harmful repercussions of these limestone concretions, in particular with regard to the clogging of the pipes and the deterioration of the heating or heated bodies, such as the immersion heaters, the boiler heating bodies or even the level control probes. of water.

 All this generates heavy maintenance and replacement costs for damaged parts.

 Apart from the installation of an autonomous water softening plant upstream of the installation concerned, the current trend is to propose a solution consisting in introducing descaling products (eg vinegar) into the installation itself, by example in the steam generator boiler.

 This solution suffers from numerous drawbacks. In particular, it requires the implementation of a rigorous and restrictive procedure comprising a certain number of manual operations, namely: introduction of the descaling product, temperature rise, rest, multiple rinses.

 It is difficult to impose this scrupulous and systematic discipline on the user. However, it is certain that without proper application of the maintenance instructions, this solution largely loses its effectiveness.

 In addition, it should be emphasized that this solution requires unproductive and expensive immobilization of the equipment.

 Finally, it does not offer any security allowing to check the good state of functioning.

 More recently, it has been proposed to integrate into a steam cooker type installation, a water softener based on the principle of ion exchange resins, requiring regular regeneration using salts. This technique experiences a rapid limit of use, due to the autonomy, which is in principle low, of the ion exchange resin container, which provides an operating capacity generally close to 10 hours.

 At the end of this period, the user must carry out a long regeneration of the resins inducing numerous manipulations. It follows naturally a corresponding immobilization of the downstream heating installation.

 Note also the lack of adaptability of such a technology to installations consuming different amounts of water, as well as to supply water of different hardness.

 On the industrial level, for heating installations, associated for example with baking ovens, such constraints are practically not acceptable. Indeed, the limited autonomy of the softening device is capable, first of all, of inducing an interruption of cooking detrimental to the user, and, in any event, of limiting the production rates.

 The present invention aims to overcome the drawbacks of known techniques by proposing a method and an installation for softening water using ion exchange resins, requiring only a small involvement of the user and capable of providing a follow-up which can be qualified as continuous, not immobilizing the downstream installation, consuming softened water.

Another object of the invention is to suppress disturbances and interruptions in the operation of
Downstream installation, due to the water softening system.

 These objects must be satisfied, while ensuring optimal elimination of the formation of lime or scale deposits and while respecting the requirements of profitability.

It was after extensive research that the
The Applicant has discovered that it is advisable to have the water softening carried out on at least part of the resin used, to simultaneously regenerate at least one other part of the resin and to repeat cyclically and alternately these steps, so as to ensure continuous softening and regeneration.

Thus, the present invention relates to a continuous water softening process, using ion exchange resins capable of reversibly trapping the ions to be removed from the water and requiring regeneration after a period of time. given use, at the end of which the resin is saturated with ions to be eliminated,
characterized in that it consists essentially in implementing the following successive steps
1) assignment of at least one activated part A of the
Water softening resin over a period of
time ta on the one hand, and simultaneous assignment of at
minus another part B of the resin, possibly
at least partially deactivated, upon regeneration,
over a period of time tr less than or equal to ta,
on the other hand,
2) allocation, at the end of period ta, of at least the
Part B activated from resin to softening
water over a period of time tb on the one hand, and
simultaneous assignment of at least part A of the
resin, at least partially deactivated, at the
regeneration over a shorter period of time or
equal to tb, on the other hand,
3) cyclic repetition of steps 1 and 2.

According to a preferred embodiment of the process according to the invention, the resin comprises two parts A and
B, one of these parts being in service and ensuring
The softening of the water, while the other part is in regeneration, so as to be at least partially activated at the end of the period of time ta or tb, that is to say at the moment when it enters into service.

 According to a first variant, it is expected that ta is equal to tb and constitutes a set value, predetermined as a function of the hardness of the water to be softened.

 According to a second variant, the hardness D5 of the softened water is measured at the output and it is expected that the time period ta or tb expires, as soon as D5 becomes greater than or equal to a predetermined threshold.

 The present invention also relates to an installation capable of being used for implementing the method.

Such a continuous water softening installation, by passage through an ion exchange resin is characterized in that it comprises
- a battery of independent resin containers
ion exchange,
- a regeneration system,
- a softening circuit,
- a regeneration circuit,
- switching means provided for connecting each of the
resin containers from battery to circuit
softening or regeneration circuit,
- a central programming and control unit.

The battery preferably comprises two containers of resin A and B, more preferably still of the column type, each comprising an inlet and an outlet and capable of operating alternately in softening mode and in regeneration mode, the entries of columns A and B being connected via conduits to an upstream switch designed to put each of them in connection with the regeneration system or with a water supply circuit to be softened, while the outputs of said columns
A and B are connected, by means of conduits, to a downstream switch capable of connecting each of them, either to a conduit for softened water to a use installation, or to a drain conduit .

 Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention.

 Fig 1 is a schematic view in a first mode of operation.

 Fig. 2 is a schematic view in a second mode of operation.

 The installation shown in Figs. I and 2 essentially comprises a battery 1 of two columns A and B of ion exchange resin, mounted in parallel and independent, a regeneration system 2, a switch 3 mounted upstream of the battery 1, a switch 4 mounted downstream of the battery 1, a programming and control unit 5, these various elements being interconnected by a set of conduits or pipes represented by two solid parallel lines and / or electrical conductors represented by a solid line.

These two columns A and B contain ion exchange resin of the type sold under the brand
DOWEX MONOSPHERE by the company DOW. This type of resin is formed from a STYRENE DVB polymer loaded with sodium ions. It can be regenerated with a sodium chloride solution.

 The installation is intended for the supply of softened water to a unit 6, such as a cooking oven.

 The upstream switch 3 comprises two inputs 73 and 83 and three outputs 93, 103 and 113. The downstream switch 4 has three inputs 94, 104 and 114 and two outputs 74 and 84.

 The two inputs 73 and 83 of the upstream switch 3 are permanently connected to the two outputs 74 and 84 of the downstream switch.

 The elements of the softening installation located upstream of the input 73 of the switch 3, as well as those located downstream of the output 74 of the switch 4, form the softening circuit. The softening circuit groups together the elements of the installation located upstream of the input 83 of the switch 3, as well as those located downstream of the output 84 of the switch 4.

Each upstream or downstream switch 3 and 4 is designed as a selection slide, actuable by a control member, for example of the double-acting or electromagnet type, slaved to
The programming and control unit 5. Each switch is thus able to adopt two positions.

 In a first position I (FIG. 1), the inputs 73 and 83 are respectively connected to the outputs 103 and 93, while the outputs 74 and 84 are in connection with the inputs 104 and 114 respectively. Column A is thus connected to inlet 73 and outlet 74, so that it is included in the softening circuit. Column B is connected to input 83 and output 84, so that it is included in the regeneration circuit.

 In a second position II, (Fig 2), the inputs 73 and 83 are respectively connected to the outputs 113 and 103, while the outputs 74 and 84 are in connection with the inputs 94 and 104 respectively. Column A is thus connected to input 83 and output 84, so that it is then included in the regeneration circuit. Column B is connected to inlet 73 and outlet 74, so that it is included in the softening circuit.

 The hard water supply to the softening system takes place via a supply line 12 (Arrow E) possibly provided with a non-return valve 13. This supply line 12 is divides, on the one hand, into two pipes 14 and 15 belonging to the regeneration circuit and, on the other hand, into a conduit 16 belonging to the softening circuit and connected directly to the input 73 of the upstream switch 3.

 The pipe 14, which is fitted with a solenoid valve 17, is slaved to the programming and control unit 5.

The solenoid valve 17 opens into the lower part of a regeneration container 18 containing a regeneration salt 19 of the resin used.

 The regeneration container 18 is provided, in its upper part, with an evacuation duct 20 connected to the inlet 83 of the upstream switch 3 and provided with a non-return valve 21 in the direction of upstream switch 3 - container 18 The container 18 also comprises a filling orifice 181 closed by a plug 182, the presence of which is detected by a sensor C3 connected to the unit 5, so that the arrival of water in the container 18 is cut when the container 18 is open (plug 182 removed). This sensor C3 also makes it possible to signal the filling of the container 18 by the operator.

 This set of elements 14, 17 to 21 constitutes the regeneration system 2.

 Preferably, the regeneration system also comprises an electrochemical sensor C1 mounted in relation to the evacuation circuit 20. The sensor C1 is able to measure the content of regeneration salt 19 at the outlet of the container 18, so as to generate information on the amount of salt 19 remaining.

The information provided by the sensor C1 can, for example, be transmitted to the programming and control unit 5, via an electrical conductor not referenced and shown in dotted lines in the drawings.

 The pipe 15 forms a rinsing circuit provided with a solenoid valve 22 slaved to the unit 5 and communicating with the discharge pipe 20, downstream of the non-return valve 21.

 The outputs 93 and 113 of the switch 3 are connected by non-referenced conduits, to the input of the column B. The output 103 of the said switch 3 is related to the input of the column A.

 Provision is also made for other unreferenced conduits connecting the outputs of columns A and B, respectively, with the input 104, on the one hand, and the inputs 94 and 114, on the other hand, of the downstream switch 4 which is provided with a drain pipe 23 connected to the outlet 84.

 The output 74 of the switch 4 is connected to a softened water supply pipe 24 of the installation for use 6. The pipe 24, which advantageously comprises a filter 25, supplies the unit 6.

 As shown in Figs. 1 and 2, an electrochemical sensor C2 can be provided symbolized in phantom. This sensor C2 is mounted on the supply pipe 24. It is designed to continuously measure the hardness D5 of the softened water at the outlet of switch 4 and to transmit it to the programming and control unit 5.

 The operation of the installation according to the invention is described in detail below.

The programming and management unit 5 governs the implementation of the method according to the invention, by intervening at the level of the upstream and downstream switches 3 and 4 and of the solenoid valves 17 and 22 and, possibly, by processing information on the hardness D5 of the softened water and on the quantity of regeneration salt 19 remaining, emanating from the sensors C2 and
C1.

 In a first operating state, the unit 5 actuates the switches 3 and 4 in position I. In this example, it will be assumed that the column A contains activated resin ready for use and the column B of the resin disabled to regenerate.

 Fig. 1 illustrates this operating state in which column A is in softening mode and column B in regeneration mode.

 In another scenario, it is possible that columns A and B both contain activated resin ready for use. The unit 5 is naturally programmable, so that only one of the columns operates in softening mode and the other is at rest, for the first implementation of the method.

 In the hypothesis considered, it should be added, with regard to unit 5, that at time t0, it controls the closing of the solenoid valve 22 and the opening of the solenoid valve 17.

 After switching on the installation, hard water is admitted under pressure into your supply line 12. Part of this water is conveyed, via pipe 16 and the upstream switch 3, to column A containing at least partially activated resin. Hard water migrates through the resin and thus discharges calcium and magnesium ions. The softened water obtained at the outlet of column A reaches the downstream switch 4, which directs it into the supply line 24 of the installation of use 6.

 Simultaneously with this, another part of the hard water coming from the supply line 12 circulates through the pipe 14. This hard water is devoted to the regeneration of column B and, to this end, percolates through the regeneration salt 19 contained in the container 18. The regeneration solution thus obtained is conveyed to column B, via the evacuation duct 20 and the upstream switch 3. This solution then migrates through column B containing resin , at least partially deactivated, which thus discharges calcium and magnesium ions and recharges sodium ions.

At the outlet of column B, the solution containing the calcium and magnesium ions is directed towards the drain pipe 23 via the downstream switch 4. This regeneration operation properly takes place over a limited period tr1 pre programmed by the user on unit 5, depending on the characteristics of the resin (quantity, nature, etc.) and
Installation (flow).

 At the end of tr1, the unit 5 activates the control means 17 and 18, so that the water from the supply line 12 passes through the rinsing line 15, then in the same way as the previous regeneration solution. via line 20 via switch 3, column B and switch 4 to be finally discharged as effluent via line 23. This water allows rinsing of column B which has just been regenerated or reactivated. This rinsing step takes place over a period tr2, which is also a set value, entered beforehand in the unit 5 by the user. Like tr1, tr2 is determined according to the characteristics of the resin and the installation.

 The duration tr equal to tr1 + tr2 of the regeneration and rinsing steps is preferably chosen so that it is in all cases less than or equal to the duration ta of operation of the column A in softening mode.

 Furthermore, as soon as the sensor C1 signals to the central unit 5 a salt content of the regeneration solution below a certain threshold fixed in advance and entered in the central unit 5, the latter warns the user, by any suitable means, from the depletion of the generation salt reserve. If necessary, it can interrupt the process.

 According to a first form of the invention, the unit 5 is placed under the dependence of the sensor C2 which is responsible for assessing the quality of the water supplied to the oven 6. The sensor C2 signals to the central unit 5 the passage of the hardness DS of the softened water, below a certain sensitivity threshold, predetermined as a function of the tolerance of the installation for use 6 with respect to limestone.

 As soon as this threshold is reached, the central unit 5 controls the permutation of the columns by actuating the switches 3 and 4 from position I towards position II (FIG. 2).

In the absence of a sensor C2, the duration of the operation of column A in softening mode, and consequently of column B in regeneration mode, is predetermined by the user as a function of the hardness of the water in the network used. This fixed duration is programmed in the central unit 5, which, for this purpose, is provided with time switches. At the end of this period,
The central unit 5 controls the permutation of the columns and the situation is that illustrated in FIG. 2. Switches 3 and 4 are then in position II.

 The operation is established in contrast to that described above from column A placed in regeneration mode and from column B placed in softening mode.

 The permutation cycle is thus repeated throughout the duration of the softened water supply of the installation of use 6.

 The user thus benefits from an installation implementing a continuous softening process, operating automatically, practically requiring no human intervention. In addition, this installation is of reasonable cost both in manufacturing and in use.

Furthermore, this installation and this following process
The invention can easily be incorporated into an installation of the cooking oven type using a steam generator.

 The invention is not limited to the example described and shown. Various modifications can be made without departing from its scope.

Claims (11)

 1 - Continuous water softening process, using ion exchange resin capable of reversibly trapping the ions to be removed from the water and, requiring regeneration after a given period of use , at the end of which the resin is saturated with ions to be eliminated,  characterized in that it consists essentially in implementing the following successive steps  1) assignment of at least one activated part (A) of the  water softening resin over a period of  time (ta), on the one hand, and simultaneous assignment  at least one other part (B) of the resin,  possibly at least partially deactivated, at  regeneration over a period of time (tr)  less than or equal to (ta), on the other hand,  2) allocation, at the end of period (ta), of at least  the active part (B) of the softening resin  water over a period of time (tb), on the one hand,  and simultaneous assignment of at least part (A) of  the resin, at least partially deactivated, at the  regeneration over a shorter period of time (tr)  or equal to (tb), on the other hand,  3) cyclic repetition of steps 1 and 2.  2 - A softening method according to claim 1, characterized in that the resin is divided into two parts (A) and (B).  3 - Softening method according to claim 1 or 2, characterized in that (ta) is equal to (tb) and constitutes a predetermined set value, depending on the hardness of the water to be softened.  4 - Softening process according to claim 1 or 2, characterized in that the duration (Ds) of the water after softening is measured using at least one suitable sensor and in that it is expected that the time period (ta) or (tb) comes to an end when (D5) becomes greater than a certain predetermined threshold.  5 - Installation for continuous water softening by passage through an ion exchange resin, characterized in that it comprises  - a battery (1) of containers (A, B) independent of  ion exchange resin,  - a regeneration system (2),  - a softening circuit (16, 73, 74, 24),  - a regeneration circuit (14, 17 to 21, C1, 83, 84,  23),  - switching means (3, 4) provided for connecting  each of the resin containers (A, B) of the  battery (1) to the softening circuit or  regeneration circuit,  - a central unit (5) for programming and  ordered.  6 - Installation according to claim 5, characterized in that the battery comprises two resin containers (A) and (B), preferably of the column type, each comprising an inlet and an outlet and capable of operating alternately in softening mode and in regeneration mode, the inputs of columns (A) and (B) being connected by means of conduits to an upstream switch (3) designed to put each of them in connection with the regeneration system or with a conduit water supply (12) to be softened, while the outlets of said columns (A) and (B) communicate, via conduits, to a downstream switch (4) capable of connecting each of them, either to a conduit for softened water (24) to a use installation (6), or to a drain conduit (26).  7 - Installation according to claim 5 or 6, characterized in that the softening circuit comprises  - a pipe (16) connected to the supply line (12),  - an input (73) of the upstream switch (3)  connected to the pipe (16),  - a water supply pipe (24)  softened installation installation (6)  connected to the output (74).  8 - Installation according to any one of claims 5 to 7, characterized in that the regeneration circuit comprises  - a pipe (14) connected to the pipe  inlet (12) and provided with a solenoid valve (17),  subject to the unit (5),  - a regeneration container (18) containing a  regeneration salt (19) connected to the  pipeline (14),  - an exhaust duct (20) provided with a valve  non-return (21) and connected to the container (18),  - a drain pipe (15) equipped with a  solenoid valve (22) slaved to the unit (5), said  pipe (15) connecting the supply line  (12) to the exhaust duct (20), downstream of the  non-return valve (21),  - an input (83) of the upstream switch (3)  connected to the exhaust duct (20),  - an output (84) of the downstream switch (4),  - and a drain pipe (23) connected to  Said outlet (84).  9 - Installation according to any one of claims 5 to 8, characterized in that the central unit (5) is equipped with a member for programming the operating time in softening mode, so that at each term of programmed duration, the central unit controls the permutation of the resin containers (A, B) by action on the upstream and downstream switches (3, 4).  10 - Installation according to any one of claims 5 to 9, characterized in that it comprises a sensor for measuring (C2) the hardness (D5) of the water softened by the resin, this sensor being in communication with The central unit (5) and the latter being able to compare the measured hardness (Ds) with a set value and to generate the command for the permutation of the resin containers (A, B) via the switches (3, 4) , as soon as the hardness (Ds) measured is greater than the set value.  II - Installation according to any one of claims'5 to 10, characterized in that it comprises a sensor (C1) for measuring the regeneration salt content disposed at the outlet of the regeneration container (18) and coupled to The central unit (5).  12 - Installation according to any one of claims 5 to 11, characterized in that it is applied to steam generators.