EP0654635B1 - Rechargeable steam generator - Google Patents

Abstract

The invention relates to a steam generator comprising an orifice for feeding water to a porous material (109), a heating element (192) passing through this porous material and an outlet orifice for the steam created by heating this water, the generator being characterised in that the porous material and its heating element are contained in an envelope (18) arranged in a sealed cassette (10) which is removable and connected during functioning to a fixed part of the generator (12, 14) containing means for feeding water, means for controlling the heating element and means for taking off steam. The sealed cassette is connected to the fixed part of the generator by means of clips (20) so as to allow rapid connection and disconnection and it comprises an orifice for admission of the water connected to an internal envelope containing an element for heating the water around which a porous material is compressed, this envelope comprising over its entire surface orifices (188) for removal of the steam produced by the heating element and the steam being extracted from the cassette via a steam outlet orifice. <IMAGE>

Description

The present invention relates to a steam generator as defined in the preamble of claim 1.

A steam generator conventionally consists of a water tank comprising a filling duct and communicating with a distribution by a water injection device, this chamber comprising an orifice outlet for the evaporation of the steam created by heating the water in the tank.

It is known that the life of these steam devices is limited by the scale formation resulting from the vaporization of accumulated tank water at the inlet and outlet ports of the vaporization chamber. This service life is all the shorter as the water used has a high rate of limestone.

Current solutions to this problem posed by scaling of generators are multiple but not at all satisfactory: the water pretreatment or the use of demineralized water is expensive and, in this second case, it sometimes requires the use of special materials; regular rinsing of the device constitutes a constraint ill-suited to professional use; the destruction of scale by creating passages between the tank and the area evaporation requires the use of complex mechanical devices such as anti-scale rods; similarly, the detection of scaling by measuring the pressure of the fluid circulating in the generator requires the use of sensors whose surveillance must be constant.

We also know from EP-A-0 317 444 a generator vapor comprising an enclosure containing a liquid to be vaporized and, inside this enclosure, a rapid vaporization block comprising at least one resistance electric heater housed in a porous body which dips into the liquid and is enclosed in an openwork envelope. However, such a steam generator does not optimize maintenance operations.

The present invention aims to overcome the aforementioned drawbacks, that is to say to offer a generator that does not require monitoring or maintenance individuals or specific water treatment. Another object of the invention is to produce a steam generator that is simple to use, reliable and inexpensive.

These aims are achieved by a steam generator comprising a envelope in which a porous material and a heating element are contained passing through this porous material, the envelope itself being arranged in a enclosure connected in operation to water supply means, means for controlling the heating element and the means for withdrawing steam created by heating the water introduced into the enclosure, the enclosure constituting a removable waterproof cassette connected by clips allowing connection and a quick disconnection to a fixed part of the generator containing said means of water supply, said means for controlling the heating element and said vapor withdrawal means.

The separation in a cassette of the elements for generating steam from other components of the generator makes it possible to produce a device particularly economical insofar as the cost of this cassette is reduced (it comprises few elements) and its very high reliability (these elements are simple).

In a first embodiment, the water supply means may include an external reservoir and a pump placed between this reservoir and a water supply orifice and allowing selective introduction of water into the generator. Preferably, the water pumped from the reservoir is introduced into a upper part of the cassette via a spray bar.

The use of this pump / tank assembly allows a supply generator, the tank can be filled at any time without any capacity limitation. In addition, the water being introduced by the pump at a pressure higher than the internal pressure of the generator, it is easy to direct it to a place where its transformation into vapor is the most efficient or even where scaling can be done simply.

In a second embodiment, the water supply means may also include manual filling means comprising a siphon to limit the height of the cassette filling with water, these means of filling being provided with means for cutting off the heating and the power supply in water controlled from the rotation of a filling plug placed in entry of these filling means.

This automatic shutdown ensures maximum safety during filling avoiding any production of steam during this.

This generator also comprises means for regulating the vapor in cassette outlet for continuous steam production.

Control light or sound indicators allow control constant water level, flatness and scaling of the cassette, the latter control being obtained by a device for measuring the conductivity of the water before evaporation which is connected to the cassette.

The present invention also relates to a removable steam cassette intended to be implemented with the preceding steam generator. She includes a sealed external enclosure, a water inlet orifice distributing this water to an envelope internal containing a water heating element around which is compressed a first porous material, this envelope comprising over its entire surface orifices for the evacuation of the steam produced by the heating element and the steam being expelled from the cassette through a steam outlet and the cassette removable being fitted with clips to allow connection and quick disconnection of the box constituting the external enclosure of the cassette by relative to the fixed part of the steam generator.

In order to avoid any backflow of vapor from the water inlet, means for closing the water inlet orifice activated when the pressure internal of the cassette is less than a determined pressure are provided in this cassette.

In a first variant embodiment of the cassette, it comprises further a second porous material separated from the first surrounding porous material the heating element by a wall extending between two opposite edges of the cassette leaving a free space for the passage of steam, the second material porous which constitutes a trap for limestone being soaked directly by water pumped from the tank through a sprayer boom. The wall has connecting holes between the evaporation zone containing the first porous material and the water supply zone containing the second porous material, in order to allow irrigation of the first porous material from partially water descaled having passed through the second porous material.

In a second variant embodiment of the cassette, the first porous material and the heating element are integrated in a ring, advantageously made of plastic, concentric with the external enclosure of the cassette and providing in its center a free cylinder in which engages up to about half of its height a steam outlet tube secured to this enclosure external circular.

With this circular structure, it is possible to obtain a generator which is capable of supplying steam in all directions of space.

Preferably, this envelope is formed of two half-housings separable with honeycombed upper and lower faces, to ensure a easy replacement of the porous material or the heating element (e.g. heating resistance, ceramic resistance or electrodes).

In a third embodiment of the cassette, the heating element water consists of a ceramic resistor inserted in the center of an element diffuser made of a heat conducting material, the first material porous being engaged under pressure between at least three fins of this diffuser and held in place by the perforated internal envelope.

High and low water level detection means intended to cooperate with means for controlling these levels present in the fixed part of the generator allow constant monitoring of the proper functioning of exchanges of existing heat at the cassette.

To determine the presence of a determined water level in the enclosure, the detection means further include a set of electrical contacts comprising on the one hand the shielding of the heating element and on the other hand a metal strip applied against the internal part of the external enclosure of the cassette.

• la figure 1 montre une vue en perspective du générateur de vapeur selon l'invention,
• la figure 2 est une vue en perspective d'un élément de la partie active du générateur constituée par une cassette amovible,
• la figure 3 est une vue en perspective de la cassette vapeur et de son dispositif de fixation au générateur selon l'invention,
• la figure 4 montre les liaisons existant entre la cassette vapeur et le dispositif de contrôle du bon fonctionnement du générateur selon l'invention,
• la figure 5 représente une variante d'alimentation du générateur à partir d'une pompe et d'un réservoir d'eau extérieur,
• la figure 6 est une vue en coupe d'un exemple de réalisation d'une cassette,
• la figure 7 montre un premier exemple de réalisation d'une cassette à section circulaire,
• la figure 8 montre un second exemple de réalisation d'une cassette à section circulaire, et
• la figure 9 illustre de manière schématique un procédé de détartrage de la cassette vapeur à partir d'un ensemble pompe-réservoir externe.

Other characteristics and advantages of the present invention will emerge more clearly from the following description, given by way of non-limiting illustration, with reference to the appended drawings, in which:

• FIG. 1 shows a perspective view of the steam generator according to the invention,
• FIG. 2 is a perspective view of an element of the active part of the generator constituted by a removable cassette,
• FIG. 3 is a perspective view of the steam cassette and its device for fixing to the generator according to the invention,
• FIG. 4 shows the connections existing between the steam cassette and the device for controlling the correct operation of the generator according to the invention,
• FIG. 5 represents a variant supplying the generator from a pump and an external water tank,
• FIG. 6 is a sectional view of an exemplary embodiment of a cassette,
• FIG. 7 shows a first embodiment of a cassette with a circular section,
• FIG. 8 shows a second embodiment of a cassette with a circular section, and
• FIG. 9 schematically illustrates a method for descaling the steam cassette from an external pump-reservoir assembly.

Figure 1 is a general view of a steam generator according to the invention. This generator comprises a housing assembly provided with a housing upper 14 and a lower housing 12 and inside which can be placed a Steam cassette 10. This connectable and disconnectable cassette by the user is connected to the upper and lower housings 14, 12 by clamps 20 having a classic structure of "clips" and allowing a quick extraction to proceed to the loading / unloading the cassette.

The lower case 12 has a connection plate 16 on which comes into contact with the rear face of the cassette 10 in order to ensure the connections electrical and mechanical between this cassette and the generator body.

The cassette 10 is in the form of a parallelepiped enclosure waterproof, without this particular form being limiting (it will be described later an example of a circular section cassette), inside which is fixed a envelope 18, the structure of which will be better detailed with reference to FIG. 2. The cassette 10 has on its internal surface ribs on which rests the envelope and which, by the difference in size of some of them, in maintain.

FIG. 2 shows more precisely the structure of the envelope 18 which is present in the form of a parallelepiped made up of two half-housings, one upper 180 and the other lower 182, interconnected by fastening means 184, 186 arranged on each of these two half-housings, in order to facilitate the disassembly. The upper and lower faces of this parallelepiped are honeycombed a multitude of orifices 188.

The envelope is filled with a porous material 190 surrounding an element heater, for example a heater resistor 192 (but electrodes or a ceramic resistance for example can also be used), this envelope intended to maintain the porous material geometrically with respect to water and keep its compression around the heating element. Considering temperatures involved, below 100 ° C, the envelope can be produced very simply and inexpensively in a plastic material. An intake port water 194 is practiced at the end of this envelope, the vapor produced by the water heating by the heating element escaping through the different alveoli 188.

FIG. 3 shows in detail the connections made between the cassette 10 and the connection plate 16 of the generator housing. We find some of the elements described above as the fixing means 20 of this cassette to the upper housing 14 of the generator (a similar means is present on the face bottom of the cassette to ensure a connection with the bottom box) or the heating resistance of the envelope which can consist of two resistors in series 192a, 192b and which emerges from the cassette by its rear face 22, to ensure its electrical connection with the connection plate 16. A conduit 24 fixed at the level of the inlet orifice 194 of the envelope also emerges from this rear face and crosses the connection plate 16 in order to be fixed tightly (this tightness being guaranteed by the use of an O-ring for example) on a water supply nozzle 26. At the inlet of this conduit, inside the cassette, are arranged sealing means 28 of the water intake orifice 194 (see figure 1) which are activated when the internal pressure of the cassette is lower than a specified pressure, eliminating the risk of vapor rejection through the water intake port. Finally, a steam outlet orifice 30 is made. also on the rear side of the cassette for steam evacuation escaping through the cells 188 of the envelope 18 contained in this cassette.

Notches, for example 32 and 34, made in the body of the cassette allow to receive electrical contacts or electrodes allowing various detections. Thus, a detection of the water level, high and low, allowing to check an overflow or a lack of water in the cassette can be implemented. A detection of the horizontality of this cassette can also be carried out. Electrodes intended for measuring the conductivity of water before evaporation must also be provided to allow a change of the porous material when it becomes scaled by the presence of limestone or non-mineral too much soluble.

Steam regulation means 36 at the outlet of the cassette are provided in order to limit the vapor volume created and to obtain a continuous emission of steam. These means include a solenoid valve and a pressure switch whose pressure setting (steam pressure produced) is preferably chosen to be less than 0.5 bar. Of course, the diameter of the steam outlet conduits will be adapted in consequence to limit the pressure losses.

The nozzle 26 has a siphon portion 260 to limit the height of the cassette water filling. A contactor 262 placed on this nozzle activates the electrodes for measuring the water level during filling. These filling means 26 also include means for cut off the water supply, for example a cam contact 264, controlled from the rotation of a water filling cap 266 placed at the inlet of these filling means and thus prohibiting any production of steam.

The operation of the generator according to the invention is particularly simple. The water being introduced into the generator through the nozzle 26 (the plug of filling having of course been previously removed, this withdrawal causing a cut automatic heating), this gradually fills the envelope. The different electrodes make it possible to ensure the proper functioning of this filling and signal the moment of its stop to an electronic control unit 40 (see figure 4). The cap can therefore be closed again, the generator being ready for use. Activation of the heating resistance produces steam which escaping through the cells of the envelope emerges from the cassette by the steam outlet orifice to be distributed (after regulation) to the zone (s) use of this steam. Light or sound indicators 420, 410 are designed to alert the user to the need for water level monitoring reload the cassette with water. A check of the flatness (horizontality) of the cassette is also performed.

In an alternative embodiment allowing a reduction in the total volume of the cassette and which will be described further with reference to FIGS. 5 to 8, the water supply to this cassette is carried out by a pump from a water tank outside the generator.

After a certain period of use, scaling of the cassette which must then be removed from the generator to be changed. This scaling is signaled by the electronic control unit which includes the water conductivity measurement. The light 420 or sound 410 indicators of this set allows the user to be informed of the scaling of this cassette.

Figure 5 shows another embodiment of a generator. steam according to the invention supplied by a pump-reservoir assembly. The reservoir 60 has cold water and can be filled at any time without any capacity limitation. It can be removable or not. Between the generator whose for a question of simplification of the illustration only the cassette 10 has been shown and this tank is arranged a pump 50 serving as a valve and preventing any return of hot water to the tank. This pump allows to introduce a minimum of water in the generator to keep it running knowing that the less there is faster water production is steam. Of course, the generator will include adequate detection devices, in particular level detection of water inside the generator, to determine the instants of control of the pump.

As in the previous embodiment (by manual feeding through the filling plug 266), the pump can be controlled to fill the lower part of the cassette 10 and thus soak the lower part of the porous material (the capillary body 190) which is heated by the resistor heating 192, the water being transformed from droplets within the capillary body in steam which escapes through the steam outlet orifice 30. However, in order to allow easier penetration of water into the upper part of the material porous which constitutes a zone of strong evaporation, it is preferable to bring the direct arrival of water above this porous material, for example by means a spray bar 19 arranged above the casing 18 of the cassette 10 and connected to the water inlet duct 24. Unlike the aforementioned supply, the lower part of the cassette, which provides volume scaling of the body capillary pressed around the heating resistor, this supply from above essentially causes scaling on the upper part of this porous body.

FIG. 6 shows an example of a cassette using two porous bodies 18a, 18b, one of which is directly soaked with water from a spraying boom constitutes a limestone trap. This ramp 19 brings the water pumped from the reservoir into an area comprising the second porous material 18b and separated from the area evaporator comprising the first porous material 18a surrounding the resistance heater 192 by a wall 196 extending between two opposite edges of this cassette leaving a free space for the passage of steam from the contiguous evaporation zone. Cold water from the tank is sprayed onto the upper part of the second material and creates there, due to the heat released by the vapor produced in the evaporation zone, precipitation of salts and in particular tartar. The partially descaled water will pass through the body porous 18b and come to settle on the bottom of the cassette from where it will irrigate, at through connecting holes 198 drilled in the wall 196, the first porous body 18a housed in the evaporation zone from where the steam escapes through the outlet steam 30.

Figure 7 is another embodiment of the cassette 10 which has a cylindrical shape. Of course, the other elements of the generator must be adapted to this particular geometrical configuration which makes it possible to provide steam in all directions of space. The porous body 190 and the resistance 192 are integrated in a ring 200, advantageously in material plastic, concentric with the outer casing of the cassette and sparing in its centers a free cylinder in which engages up to about half of its height a vapor outlet tube 202 secured to this outer casing. The volume of water injected by the pump and resting at the bottom of the cassette is determined to avoid a flow through the steam outlet tube during a reversal of this cassette. This volume (i.e. in practice the level of water in the envelope) can be controlled by means of a set of electrical contacts comprising by example the shielding of resistors 192 and a metal strip 204 applied against the internal part of the envelope 10. As in the embodiment previous of the cassette, the envelope can be mounted in two separable parts to facilitate maintenance, i.e. changing the element of heating or porous material.

In FIG. 8, a particular embodiment of the cassette 10 is illustrated. comprising a resistance preferably of ceramic type 210, inserted, by crimping or fitting for example, in the center of a diffuser 212 produced in a heat conductive material such as aluminum for example and provided at least three fins 214a to 214d placed on either side of its center. A porous body 216 is inserted under pressure (compressed) between each fin and held in place by a perforated circular envelope 218 advantageously consisting of a simple grid.

Figure 9 attempts to illustrate very schematically a method allowing a soiling of a cassette to allow its reuse. For this, it is necessary to connect the water intake duct of the cassette to pumping means (for example the water supply pump 50) themselves connected to a water tank (for example the external tank 60) and to connect the heating element to an external control device 70. The pump draws water from the tank and enters it into the cassette where it is heated to a determined temperature below its evaporation value but above 60 ° C, to retain tartar and insoluble minerals. The water can then be extracted through the steam outlet 30.

Claims (18)

1. A steam generator comprising a case (18) which contains a porous material (190) and a heater element (192) passing through said porous material (190), the case (18) being itself disposed in an enclosure (10) that is connected in operation to water feed means, means for controlling the heater element, and means for taking off the steam created by heating the water injected into the enclosure, characterised in that the case (10) constitutes a removable sealed cassette that is connected by means of clamps (20) suitable for enabling rapid connection and disconnection to a fixed portion of the generator (12, 14) containing said water feed means, said means for controlling the heater elements, and said means for taking off the steam.
2. A steam generator according to claim 1, characterised in that the water feed means comprise an external tank (60) and a pump (50) placed between the tank and the water feed orifice, and enabling water to be selectively injected into the generator.
3. A steam generator according to claim 2, characterised in that the water pumped from the tank (60) is injected into the top portion of the cassette (10) by means of a spray strip (19).
4. A steam generator according to claim 1, characterised in that the water feed means comprise manual filling means (26) having a siphon (260) for limiting the depth to which water can be filled in the cassette.
5. A steam generator according to claim 4, characterised in that the manual filling means further comprise means (264) for interrupting heating and water feed, which means are controlled by rotation of a filler stopper (266) placed at the inlet of said filler means.
6. A steam generator according to claim 1, characterised in that it further comprises steam regulator means (36) at the outlet from the cassette (10).
7. A steam generator according to claim 1, characterised in that it further comprises visible indicators (420) or audible indicators (410) for monitoring water level, planeness, and clogging by scale of the cassette (10).
8. A steam generator according to claim 7, characterised in that clogging by scale is monitored by a device (40) for measuring the conductivity of the water prior to evaporation, which device is connected to the cassette (10).
9. A removable steam cassette designed to be implemented with a steam generator according to any one of claims 1 to 8, comprising an extended outer enclosure, a water inlet duct (24) distributing said water to an internal case (18) containing a heater element for heating said water (192), a first porous material (190) being compressed around the heater element, said case including orifices (188) over its entire surface for evacuating the steam produced by the heater element, the steam being expelled from the cassette via a steam outlet orifice (30), and the removable cassette being fitted with clamps (20) for enabling rapid connection and disconnection from the box constituting the outer enclosure of the cassette with respect to the fixed portion (12, 14) of the steam generator.
10. A removable steam cassette according to claim 9, characterised in that it comprises shutter means (28) for shutting the water admission orifice and activated when the pressure inside the cassette is less than a determined pressure.
11. A removable steam cassette according to claim 9, characterised in that it further comprises a second porous material (18b) that is separated from the first porous material (18a) surrounding the heater element (192) by a wall (196) extending between two opposite sides of the cassette and leaving an empty space for the passage of steam, the second porous material (18b) which constitutes a trap for scale being soaked by means of a spray strip (19) directly with the water pumped from the tank.
12. A removable steam cassette according to claim 11, characterised in that the wall (196) includes orifices (198) providing communication between the evaporation zone that contains the first porous material (18a) and the water feed zone that contains the second porous material (18b), thereby enabling the first porous material to be irrigated with partially descaled water that has passed through the second porous material.
13. A removable steam cassette according to claim 9, characterised in that the first porous material and the heater element are integrated in a ring (200) that is advantageously made of plastics material, that is concentric with the outer enclosure of the cassette (10) and that has a free cylinder in its center into which a steam outlet tube (202) secured to said circular outer enclosure plunges to about half-depth.
14. A removable steam cassette according to any one of claims 9, 11 and 13, characterised in that the case (18) is made up of two separable half-boxes (180, 182; 200) having pierced top and bottom faces in order to make it easy to replace the porous material or the heater elements.
15. A removable steam cassette according to any one of claims 9, 11 and 13, characterised in that the heater element (192) for the water circulating through the porous material is selected from the elements of the following group: a heater resistance element, a ceramic resistance, and electrodes.
16. A removable steam cassette according to claim 9, characterised in that the water heater element is constituted by a ceramic resistance (210) inserted in the center of a diffuser element (212) made of a heat-conducting material, the first porous material (216) being engaged under pressure between at least three fins (214a to 214d) of said diffuser and being held in place by the perforated internal case (218).
17. A removable steam cassette according to any one of claims 9 to 16, characterised in that it includes high and low water level detection means detecting the levels for co-operating with means (40) for monitoring said levels and present in the fixed portion of the generator.
18. A removable steam cassette according to claim 17, characterised in that, in order to determine the presence of a determined level of water in the enclosure, said detection means further include a set of electrical contacts including both the screening of the heater element (192) and a metal strip (204) pressed against the internal portion of the outer enclosure of the cassette (10).

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