EP0186544A1 - Self-descaling device - Google Patents

Abstract

1. Installation for the production of hot water or vapor of a type comprised of a cold water source, means for controlling the cold water flow from said source to a receiver, a receiver heated by appropriate means and means for producing hot water or vapor supplied with water through said receiver, said receiver comprising, furthermore, drainage means, the part of the installation upstream of all heating means being called "cold zone" (Zf) and the part of the installation dowstream of said receiver being called "hot zone" (Zc), characterized in that it comprises, in the hot zone (Zc), a chamber (6) which opens, on the one hand, into said production zone (2) and, on the other hand, into the drainage means (5) and it that the supply conduit (1) is equipped, in the cold zone (Zc), immediately dowstream from the control means (3), with a derivation (4) discharging into said drainage means (5).

Description

The subject of the present invention is a self-descaling process for installations for producing hot water or steam, for example that an appliance has been misted for bakery ovens, a water heater, a percolator, or any other installation. domestic or industrial using steam or hot water.

In such installations, scale formation is all the more rapid and tenacious as the water stays longer in the hot zone of the installation.

It follows that it is necessary to descale the installation periodically, with the drawbacks that this entails in terms of costs and the inconvenience caused by the interruption of the operation of the installation.

Of course, it is possible to largely avoid scaling of the installation by providing, upstream of the latter, a water softener, but in this case, on the one hand, we must face the costs represented by the periodic replacement of the ion exchange resin and, on the other hand, the installation for producing hot water or steam is supplied with water whose pH has been modified.

The object of the present invention is to remedy these drawbacks by proposing a method and an installation of self-scaling which require no intervention by the user, no energy input, no chemical product and which are simple and economical.

More specifically, the present invention applies to installations of the type comprising a source of cold water, means for controlling the flow of cold water from said source to a receiver, a receiver heated by suitable means and means for producing hot water or steam supplied with water via said receiver. said receiver comprising, in addition, means of evacuation to the sewer, the part of the installation upstream of all heating means being called "cold zone" (Zf) and the part of the installation downstream of said receiver being called "hot zone" (Zc).

• - à prévoir lesdits moyens de commande de l'écoulement de l'eau en zone froide (Zf) et
• - à interrompre, de temps à autre, l'écoulement de l'eau à l'aide desdits moyens de commande, en permettant l'évacuation rapide à l'égout de l'eau en aval de la zone froide (Zf), au moins au travers dudit récepteur (6) provoquant ainsi la montée en température du récepteur vide, puis
• - à rétablir l'écoulement de l'eau froide, avec pour résultat un choc thermique dans le récepteur.

The object which the invention has set itself is achieved in the sense that it proposes a process consisting of:

• - to provide said means for controlling the flow of water in the cold zone (Zf) and
• - to interrupt, from time to time, the flow of water using said control means, allowing rapid evacuation to the sewer of water downstream of the cold zone (Zf), at less through said receiver (6) thus causing the temperature of the empty receiver to rise, then
• - to restore the flow of cold water, resulting in a thermal shock in the receiver.

Advantageously, the method consists in giving said receiver the form of a chamber.

In this way, when the water supply to the installation is interrupted and the water is quickly evacuated to the sewer, through the chamber, the water still being downstream of the control means of the 'flow, only a film of water remains on the walls of the chamber, which film evaporates instantly, leaving, if necessary, only a thin film of unstructured tartar on the walls of the chamber. When the water supply is restored, it begins to vaporize as soon as it reaches the hot zone and the water-steam mixture suddenly enters the chamber with instant transformation of the residual water into turbulent vapor and effect which detach the thin film of tartar and reduce it to particles which the water immediately entails.

The intermittent and rapid evacuation of the room, in a hot zone, then the intermittent and abrupt re-admission of cold water, therefore results in self-descaling.

It has certainly already been proposed, in French Patent No. 1,112,473, a process for removing the salts which are deposited on the heating surfaces of the steam generators.

In normal service the water passes through the receiver that constitutes the exchanger (4) to reach the superheater (7) and the scale is deposited in this exchanger which is, moreover, there for this purpose (protection of the superheater).

When a critical quantity of scale has settled in the exchanger (4), most of the water is drifted which by-passes the exchanger and. feeds the superheater directly, while the remaining fraction of the water continues to reach the exchanger, passes through it and is. evacuated to the sewer after having dissolved the scale, deposited in the exchanger.

It is specified, page 2 right column, end of the same paragraph, that the exchanger wash water must be as hot as possible to avoid cooling it. Under these conditions, it is permissible to wonder why the passage of the current of hot water in the heater causes a scale deposit in normal operation phase and the removal of the scale deposit in the washing phase, nothing distinguishing these two otherwise the quantity of water circulating in the exchanger.

On the contrary, according to the invention, the elimination of tartar results from the thermal shock which occurs as a result of the total interruption of the flow of water in the chamber, of the rise in temperature of the chamber which does not then exchanges more calories with the water, and the re-admission into the hot room of the cold water supplying the installation.

Given the operating mode of the installation known from French Patent No. 1,112,473, there can be no thermal shock since the flow in the exchanger is not interrupted, but only reduced the flow, taking care not to cool the exchanger during the washing phase.

According to the invention, in the case where the production of hot water or steam is discontinued, the interruption and restoration of the flow of water for the intermittent production of hot water or steam is not distinguished the interruption and restoration of water for the implementation of the auto-scaling operation.

In other words, there is no need to provide special means for obtaining an intermittent flow of water, with a view to self-descaling.

It is understood that, in this case, the time which elapses between the interruption and the reestablishment of the flow of the water may be irregular, depending on the frequency of hot water or steam needs.

To guarantee total emptying of the chamber, the method according to the invention consists in providing, in the cold zone, immediately downstream of the means for controlling the flow of water, means for evacuating the water. down the drain.

In this way, when the means for controlling the flow of water are closed and after a portion of the water contained between these control means and the chamber has escaped by said means of evacuation, air enters these evacuation means into the zone between the control means and the chamber, thus facilitating its emptying. In addition, the air advantageously cools the control means.

In a simple form of implementation of the invention, the method consists in permitting permanent evacuation of the water in the sewer from the chamber, and possibly, from the zone immediately downstream of the control means of the water flow, the evacuation rate not being significant compared to the rate towards said production area.

Advantageously, the method consists in maintaining, in said chamber, a tank bottom adapted to form a floatation bath for possible particles of tartar.

• - en zone froide, des moyens de commande de l'écoulement de l'eau, et
• - en zone chaude, une chambre débouchant d'une part dans ladite zone de production et, d'autre part, à l'égout.

The present invention also relates to an installation for implementing the method described above, said installation using a water supply pipe for supplying a zone for producing hot water or steam and comprising :

• - in the cold zone, means for controlling the flow of water, and
• - in a hot zone, a chamber opening on the one hand into said production zone and, on the other hand, into the sewer.

The supply line may have, in the cold zone, immediately downstream of the control means, a bypass leading to the sewer. The drainage outlet (s) are advantageously permanently open, the discharge rate is not significant compared to the flow to the production area.

To make a flotation bath for possible particles of tartar, the evacuation to the sewer of the chamber is done by a tube whose evacuation opening is raised relative to the bottom of the chamber.

Advantageously, the chamber contains, opposite its water inlet, a jet breaker capable of storing calories when the chamber is empty and of returning them to the water when the latter is readmitted into said bedroom. When the mixture of water and steam mentioned above enters the chamber, it collides with the hot jet breaker which instantly completes its vaporization.

• - la figure 1 représente schématiquement l'installation selon l'invention adaptée à produire de la buée dans un four de boulangerie,
• - la figure 2 est une vue à plus grande échelle de la chambre, avec omission de la paroi frontale, et
• - la figure 3 est un schéma illustrant l'application de l'invention à une installation de production.

The invention will be better understood on reading the following description made with reference to the accompanying drawings, in which:

• FIG. 1 schematically represents the installation according to the invention adapted to produce fogging in a bakery oven,
• FIG. 2 is an enlarged view of the chamber, with the front wall omitted, and
• - Figure 3 is a diagram illustrating the application of the invention to a production installation.

If we refer to Figure 1, we see a supply line 1 adapted to convey water to a zone 2 of steam production.

The installation includes a cold zone Zf and a hot zone Zc. By cold zone is meant an area in which the temperature is between ambient temperature and about 35 ° C. In the cold zone, there is provided a valve 3 controlling the flow of water in the pipe 1 and a bypass 4 joining the pipe 1 to a pipe 5 for evacuation to the sewer.

A chamber 6 is interposed, in the hot zone, between the pipe 1 and the steam production zone 2. This chamber 6 is mounted against the wall of the furnace (not shown) by appropriate fixing means 7. The chamber 6 comprises a water inlet pipe 8, a water outlet pipe 9 extending through a pipe 10, the end of which forms a water spray nozzle, and a pipe 11 joined to a bypass 12 opening into the drain pipe 5. The pipe 11 protrudes inside the chamber 6, which has the effect of maintaining a tank bottom 13 as best seen in FIG. 2.

A jet breaker 14 is provided directly above the water inlet pipe 8 in the chamber 6.

As can be seen from FIG. 1, the diameter of the branches 4 and 12 is much smaller than that of the pipe 9, so that the leaks towards the sewer are not significant compared to the flow of water injected into the zone of steam production 2.

The operation of the installation is as follows: When it is desired to produce steam, the valve 3 is opened so that the water is conveyed through line 1 into the chamber 6 from which it emerges through line 10 to be sprayed by the nozzle in the steam production zone 2. A minor quantity of water escapes to the sewer via leads 4 and 12.

When it is desired to interrupt the production of steam, the valve 3 is closed, so that a large part of the water contained in the pipe 1, in the zone between the valve 3 and the bypass 4, escapes by this bypass to the evacuation pipe in the sewer 5, while the rest of the water contained in the pipe 1 downstream of the valve 3 and the water contained in the chamber 6 flows by the bypass 12 towards the evacuation pipe to the sewer 5. When the bypass 4 is empty, air enters the circuit from the pipe 5, which has the effect of facilitating the emptying of the chamber 6 and cooling the valve 3. The chamber 6 empties quickly and the liquid film remaining on its walls evaporates instantly. The mineral salts contained in this liquid film are deposited on the walls of the chamber 6 in the form of a thin film of unstructured tartar. When the water circulation is restored by opening valve 3, the cold water heats up and vaporizes at least partially as soon as it enters the hot zone. When it enters the hot chamber 6 through the pipe 8, the water-steam mixture strikes the hot jet breaker 14 so that the mixture finishes vaporizing, causing a thermal shock and a turbulence effect. It follows that the thin film of tartar previously deposited disintegrates into fine particles which are entrained either in the steam production zone 2, or directly in the sewer by the leak taking place according to the bypass 12. It particles of tartar may not be immediately removed, in which case they fall to the bottom of the chamber 6. The mouth of the tube 11 being raised relative to this bottom, the latter cannot be blocked by these particles. When the water supply to the system is again interrupted, there remains, after the water contained in the chamber 6 has flowed through the bypass 12, a tank bottom 13 which disappears by evaporation.

The particles of tartar resting on the bottom are swept away by the turbulence created during the re-admission of water and evacuated like those which come from the deposit of tartar on the other walls of the tank.

It is understood that, in this way, the hot water does not remain in any part of the installation, a stay which promotes the formation of structured tartar strongly adhering to the walls. In the case of the invention, the hot water is periodically and rapidly removed, which only allows the formation of an unstructured tartar film easily removable by thermal shock and turbulence.

The invention is applicable both to an installation for the discontinuous production of hot water or steam and to an installation for continuous production, as shown in FIG. 3, where the same components are designated by the same references as 'in Figure 1 but accompanied by the prime or second signs.

The reference 15 designates a timer actuation mechanism alternately actuating the valves 3 'and 3 ". It is understood that, when the mechanism 15 opens the valve 3', the water enters the chamber 6 ′ and flows through the line 10 ′ to the steam production zone 2. When the mechanism 15 closes the valve 3 ′ and opens the valve 3 ″, the water enters the chamber 6 "and flows through line 10" to the steam producing zone 2. In this way, steam is produced continuously in zone 2 while the periodic and alternative interruption of the flow of the water in chambers 6 'and 6 "and the periodic and alternative re-establishment of this flow in said chambers give the self-scaling effect described in detail with reference to FIGS. 1 and 2.

It is understood that the invention is not limited to the embodiment described and shown: in particular, the communication between the pipe 1 and the pipe 5, by branch 4, may not be open permanently, but only when valve 3 is closed. Furthermore, the bypass 12 permanently open, could be doubled with a discharge pipe of larger diameter and which can be opened when the valve 3 is closed to increase the speed of evacuation from the tank 6.

Claims (11)

1 - Self-descaling method for installations for producing hot water or steam of the type comprising a source of cold water, means for controlling the flow of cold water from said source to a receiver, a receiver heated by appropriate means and means for producing hot water or steam supplied with water via said receiver, said receiver further comprising means for evacuation to the sewer, the part of the installation upstream of all heating means being called "cold zone" (Zf) and the part of the installation downstream of said receiver being called "hot zone" (Zc), characterized in that it consists: - to provide said means for controlling the flow of water in the cold zone (Zf) and - to interrupt, from time to time, the flow of water using said control means, allowing rapid evacuation to the sewer of water downstream of the cold zone (Zf), at less through said receiver (6) thus causing the temperature of the empty receiver to rise, then - to restore the flow of cold water, resulting in a thermal shock in the receiver. 2 - Method according to claim 1, characterized in that it consists in giving said receiver the form of a chamber. 3 - Method according to claim 1, characterized in that, in the case where the production of hot water or steam is discontinuous, the interruption and restoration of the flow of water for the intermittent production of water hot or steam is indistinguishable from interrupting and restoring water for the implementation of the auto-scaling operation. 4 - Method according to any one of claims 1 to 3, characterized in that it consists in further providing, in the cold zone (Zf), immediately downstream of the control means (3) of the flow of the water, means of evacuation (4) of water to the sewer. 5 - Method according to any one of claims 1 to 4, characterized in that it consists in permitting permanent evacuation of the water in the sewer, the evacuation rate not being significant with respect to the rate to said production area (2). 6 - Method according to any one of claims 2 to 5, characterized in that it consists in maintaining, in said chamber (6), a tank bottom (13) adapted to form a flotation bath for possible particles. of tartar. ' 7 - Installation for implementing the method according to any one of claims 2 to 6, said installation using a water supply line for the supply of a hot water or steam production zone, characterized in that it includes: - in the cold zone (Zf), control means (3) for the flow of water, and - In the hot zone (Zc), a chamber (6) opening on the one hand into said production zone (2) and, on the other hand, into the sewer (5). 8 - Installation according to claim 7, characterized in that the supply line (1) has, in the cold zone (Zf), immediately downstream of the control means (3), a bypass (4) opening into the sewer (5). 9 - Installation according to claim 7 or 8, characterized in that the discharge (4 and / or 12) in the sewer is permanently open, the flow of the discharge is not significant compared to the flow to the production area (2). 10 - Installation according to any one of claims 7 to 9, characterized in that the evacuation to the sewer (12) of the chamber (6) is done by a tube (11) whose discharge opening is raised relative to the bottom of the chamber (6). 11 - Installation according to any one of claims 7 to 10, characterized in that the chamber (6) contains, vis-à-vis its water inlet (8), a jet breaker capable of storing calories when said chamber (6) is empty and return them to the water when the latter is readmitted into said chamber.

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