EP1419675B1 - Cold crucible with induction heating and heat pipe cooling - Google Patents

Description

Field of the invention

The invention lies in the field of fusion certain materials with high melting temperature, such as glass, refractory oxides, oxides metal and some metals, by means of a electromagnetic induction heating. She in particular, the cold crucibles to cooled sectors and direct spinning crucibles.

Prior art and problem

Among the processes for casting and pouring products such as glass, refractory oxides, metals or even to levitate these products it is current to use cold crucibles cooled to water, heating by induction electromagnetic applied to the material contained in the crucible. Two examples of crucibles used are represented by FIGS. 1, 2 and 3.

Figure 1 represents a first type of sectorized crucible, used for these purposes. It is consisting mainly of sectors 1, a bottom 2, of an inductor 3 with several turns and a circuit of cooling 4. Sectors 1 are placed vertically, against each other, for to constitute the enclosure of the crucible. The complete background 2 this enclosure. It is specified that this background 2 can be retractable or have one or more holes for the evacuation of the materials poured into the crucible. The sectors 1 are kept against each other, thanks to a fixation by means of a wrapping 5. The cooling circuit 4 is constituted by a arrival 4E and a departure 4S of liquid from cooling, which is, in most cases, the water.

The crucible thus formed is of a shape usually cylindrical, without it being imperative. High intensity alternating current is of the order of a few thousand amps, at a frequency between a few tens of hertz and several megahertz. The tension can reach several thousand volts. The bottom of crucible 2 can to be cooled or not.

FIG. 2 shows in section a sector 1, as well as the circulation of water in a pipe 6 and 4E arrival and 4S exit. We aknowledge water circulates along the entire height of sector 1.

Figure 3 shows another kind of inductor 6, said to direct turn, consisting of a single and cylindrical spire constituting the enclosure directly containing the product to be heated. The circuit 7 is here constituted by a spiral surrounding the inductor 6. To close the crucible and to avoid the drawbacks of electrical voltages between the two terminals 6A and 6B of the inductor 6, a cold finger 8 is placed between them.

• l'utilisation d'un circuit de refroidissement dans lequel circule en grande quantité un fluide présente des risques d'explosion de vapeur en cas de fuite d'un secteur, chacun de ceux-ci étant alimenté de façon continue et à fort débit ;
• le circuit de refroidissement 4, 7, est relativement complexe.

The main disadvantages inherent to these two types of cold crucibles are the following:

• the use of a cooling circuit in which a large quantity of fluid circulates presents risks of steam explosion in the event of leakage from a sector, each of which is fed continuously and at a high flow rate;
• the cooling circuit 4, 7 is relatively complex.

Finally, there are great difficulties in maintenance in the event of damage to one of the elements of this installation.

Summary of the invention

• un fond ;
• au moins un inducteur entourant l'enceinte ;
• des secteurs juxtaposés ; et
• des moyens de refroidissement.

For this purpose, the main object of the invention is a cold crucible with electromagnetic induction heating, intended for the melting of glass, refractory oxides and metals. It mainly includes:

• a fund ;
• at least one inductor surrounding the enclosure;
• juxtaposed sectors; and
• cooling means.

According to the main characteristic of the invention, the sectors are each made up of one heat pipe with electrically insulated walls constituting the crucible as well as their own ways of cooling.

Heat pipe technology, known to man of the trade, is exposed in particular in the "Techniques of the Engineer ", Article B9545, vol. BE6.

In a preferred embodiment, each heat pipe preferably has an upper part exceeding the enclosure of the crucible constituted by the low parts from each sector, and deported to the outside. This allows the evacuation of heat by a circulation forced fluid against the upper part of the heat pipes, while allowing access from the top of the crucible.

The heat pipes of each sector can be extend under the enclosure to form the bottom. In another achievement, the bottom can also be consisting of other heat pipes different from those constituting the enclosure of the crucible.

In order to fix the upper parts of heat pipes constituting each sector, it is possible to use an electrically insulating fixing ferrule surrounding all the upper parts.

With the aim of solidariser the heat pipes, especially in their lower part, these are surrounded a wrapping.

They can also be attached to each other at by means of self-locking collars.

According to the invention, provision is also made to use an additional inductor placed under the bottom of the crucible.

Finally, it is also envisaged to use several layers of supercooled heat pipes constituting thus a long and high enclosure, the inductor being able be constituted by the superposition of inductors respective of each floor.

In a second preferred embodiment of the invention, the inductor is a single turn and direct formed of a ferrule cooled by heatpipes.

In these two achievements, cold fingers (or fingers) may consist of one (or more) heat pipe (s).

Similarly, the ferrule of the direct coil can be constituted by the continuous assembly of heat pipes not electrically isolated.

Finally, the thick ferrule, constituting the direct spire, can be machined for the realization in located heat pipes.

List of Figures

• figure 1, déjà décrite, un creuset froid selon l'art antérieur ;
• figure 2, déjà décrite, en coupe, un secteur du creuset froid décrit à la figure 1 ;
• figure 3, déjà décrite, une deuxième réalisation de l'inducteur d'un creuset selon l'art antérieur ;
• figure 4, un premier creuset selon l'invention ;
• figure 5, un collier autobloquant pouvant être utilisé sur le creuset selon l'invention ;
• figure 6, un détail du collier autobloquant de la figure 5 ;
• figure 7, une vue du dessous du creuset décrit à la figure 4 ;
• figure 8, en vue de dessous, une autre réalisation du fond du creuset ;
• figure 9, en vue frontale, une deuxième réalisation d'un creuset selon l'invention ;
• figure 10A et 10B, d'autres réalisations possibles du fond du creuset de la figure 9 ;
• figure 11, une troisième réalisation du creuset selon l'invention ;
• figure 12, un détail d'une variante de la troisième réalisation décrite à la figure 11 ;
• figure 13, une autre réalisation possible du creuset selon l'invention ;
• figure 14, un exemple de fixation des creusets les uns sur les autres ; et
• figure 15, une réalisation du creuset à spire directe refroidie par caloducs et à doigt froid constitué d'un ou plusieurs caloducs.

The invention and its various technical features will be better understood on reading the following description of several embodiments of the invention; it is accompanied by several figures representing respectively:

• Figure 1, already described, a cold crucible according to the prior art;
• Figure 2, already described in section, a sector of the cold crucible described in Figure 1;
• FIG. 3, already described, a second embodiment of the inductor of a crucible according to the prior art;
• FIG. 4, a first crucible according to the invention;
• Figure 5, a self-locking collar that can be used on the crucible according to the invention;
• Figure 6, a detail of the self-locking collar of Figure 5;
• Figure 7, a bottom view of the crucible described in Figure 4;
• Figure 8, in view from below, another embodiment of the bottom of the crucible;
• Figure 9, in front view, a second embodiment of a crucible according to the invention;
• FIGS. 10A and 10B, other possible embodiments of the bottom of the crucible of FIG. 9;
• FIG. 11, a third embodiment of the crucible according to the invention;
• Figure 12, a detail of a variant of the third embodiment described in Figure 11;
• Figure 13, another possible embodiment of the crucible according to the invention;
• Figure 14, an example of fixing the crucibles on each other; and
• FIG. 15, an embodiment of the cold-pipe cooled direct-coil crucible consisting of one or more heat pipes.

Detailed description of several achievements of the invention

A first possible realization of the crucible according to the invention is shown in FIG. materials are always melted into a part similar to that of the crucible described in FIG. formed here of sectors 11 of which part 11B is similar to the plurality of sectors 1 of the crucible of Figure 1.

The major difference is that these sectors 11 have a high portion 11H, extending from above the lower parts 11B and deviating by report in the center of the crucible. In this way, their part high 11H does not interfere with the placement of elements complementary to the installation, such as filling, thermal insulation and inductor 3. In fact, it is analogous to that used on the crucible of the prior art, represented in FIG. Figure 1.

Each sector 11 consists of a heat pipe, preferably of cylindrical section, without this form is imperative. She might be cuboid. The wall of the heat pipe must be copper or stainless steel, or any other product or metal likely to be suitable for the application considered. The coolant contained in the heat pipe constituting a sector 11 may be water or any other suitable fluid, such as sodium, germanium, the money. The upper part 11H of each sector 11, where the evacuation of the heat captured in the crucible, is surrounded by a device for forced circulation of a fluid, symbolized via a 14E entrance and a 14S exit, which runs alongside 11H high parts of sectors 11. We take advantage besides, without this being a unique solution, that the forced circulation device is present around 11H high parts to ensure the fixation of these by means of a ferrule 16 perforated, insulating electrically and made of composite material. The wall of each sector is electrically rendered insulating in its lower part 11B where the sectors 11 adjacent ones are in contact with each other by a suitable coating. For example, one thinks of a Plasma or process-sprayed alumina coating PVD. Regarding the fixing of sectors 11 in the lower part 11B, in this embodiment, the same wrapping as the one used in the crucible, previously described in Figure 1. With reference to the FIG. 5, this wrapping can be replaced by a self-locking collar 15, made of composite material, electrically insulating. Closing such a necklace self-locking device 15 is illustrated in FIG. two ends 15A and 15B snap one into the other, by means of hooks 15C.

The crucible, as shown in Figure 4, has a bottom 12 which is, in this case, cooled by extension 11F of sectors 11, below their lower parts 11B.

It is noted that bottom 2 might not be cooled and be open in the middle to allow the passage of long pieces or to evacuate the resolidified product.

Figure 7 shows, in bottom view, the same crucible of Figure 4, the bottom 12 being removed. We thus distinguish the low ends 11B of sectors 11 that extend from the periphery towards the center of the crucible. In order to cover all the surface of the bottom of the crucible, these different low ends 11B of sectors 11 have lengths different, so as to entangle the others like a wooden floor with sticks and to carry out the complete recovery of the bottom. Else on the other hand, the high parts 11H sectors 11 with inputs 14E and outputs 14S from coolant circulation.

Figure 8 shows another configuration of the lower ends 21B of the sectors 21 for constitute the cooling of the bottom of the crucible. In this one, we see that each low end 21B is moving towards the center of the crucible, these different lower ends 21B having different lengths to be able, not to entangle, but to cover, roughly speaking, the bottom of the crucible.

As shown in FIG. 9, the bottom 22 can also be cooled by heat pipes 24, independent of sectors 21 by penetrating the bottom 22. This arrangement is intended, inter alia, where additional inductor 29 is placed under the bottom 22 to provide additional heating of the crucible. The independent heat pipes 24 have a high part 24H similar to the upper part 14H of the sectors represented on the crucible of Figure 4, that is to say, deviating from the center of the crucible, beyond the inductor 23.

Figures 10A and 10B show the heat pipes which can be used under the substance of the crucible. The independent heat pipes 21A of FIG. 10A extend on either side of a plane of symmetry of the crucible which has been shown cylindrical. In the case of FIG. 10B, the heat pipes 21B each extend over the entire bottom surface and extend only one side of the crucible.

Figure 11 shows that the lower part crucible can be constituted by heat pipes 32 independent, positioned slightly inclined so as to cover the bottom of the crucible. They complete the sectors 31 placed between the inductor 33 and the crucible itself, the heat being evacuated through the cooling circuit the entrance has been referenced 34E and the exit 34S. This realization is particularly suitable for crucibles cold, sectorized parallelepipedic shape.

Figure 12 shows that heat pipes 32 of Figure 10 can be replaced by inclined independent heat pipes 42, the circuit cooling being adapted to this geometry, the 44E inputs and 44S outputs no longer found horizontal.

Figure 13 shows another variant of the crucible according to the invention. Indeed, she shows the superposition of several crucibles to form only one of a significant height, so a increased capacity. In view of the separated form of high parts 51H, sectors 51, the nesting of different crucibles one above the other is possible. It is noted that the lower crucible is equipped independent heat pipes 52, similar to heat pipes 32 of Figure 11. The different successive inductors 53 are equivalent to one much longer inductor that would be constituted in only one part.

As shown in Figure 14, the fixation of these different crucibles on each other can be performed by means of brazed pimples 57 on each lower end of a central part of the sector 51 and engaging in a fastener 56 attached to the lower end of the lower part 51B of sector 51 of the crucible which is just higher.

The design of this crucible applies also to a crucible using an inductor constituted of a single turn, like that of Figure 3.

Figure 15 shows the realization of a direct spin crucible whose ferrule 58 is cooled using the heat pipes 59 attached to it, one or several heat pipe (s) 60 constituting the cold finger. A variant embodiment consists in using a ferrule thick in the realization of the direct turn, a adequate machining for the in situ production of heat pipes or simply their insertion.

Claims (13)

1. Cold crucible with electromagnetic induction heating, intended for the fusion of glass, refractory oxides and metals, and principally comprising:

   a base (2, 22);

   at least one inductor (3, 33, 53);

   segments (11, 21, 31, 51) juxtaposed and constituting a crucible chamber; and

   cooling means.

   characterised in that the segments (11, 21, 31, 51) are constituted of heat pipes with electrically insulated walls, themselves constituting the cooling means.
2. Cold crucible according to claim 1, characterised in that the heat pipes have an upper part (11H, 31H, 51H) extending beyond the crucible chamber, constituted by the lower parts (11B, 31B, 51B,) of each segment and being offset to allow evacuation of heat by forced circulation of fluid against the upper part (11H, 31H, 51H) of the segments.
3. Cold crucible according to claim 1, characterised in that the sectors (11F) are prolonged under the crucible chamber to constitute the base or to cool the base (12).
4. Cold crucible according to claim 1, characterised in that the crucible base is constituted of independent heat pipes (24) independent from those (11, 31, 51) constituting the crucible chamber.
5. Cold crucible according to claim 2, characterised in that it comprises a hoop (16) for fixation of the upper parts (11H) of segments (11, 21), electrically insulating and surrounding these upper parts as a whole (11H).
6. Cold crucible according to claim 1, characterised in that the segments (11, 21, 51) are held together by strapping (5) in the lower part (11B) of the segments.
7. Cold crucible according to claim 1, characterised in that the segments are held together by self-locking collars (15).
8. Cold crucible according to claim 1, characterised in that it comprises a complementary inductor (29) to heat the crucible by being placed under the base (22).
9. Cold crucible according to claim 2, characterised in that it comprises several stages of superposed segments (51), thus constituting a long and high crucible chamber and with an inductor constituted of the inductors (53) of each of the stages superposed in this way.
10. Cold crucible according to claim 1, characterised in that the inductor is a single and direct coil constituted of a hoop (58) cooled by heat pipes (59).
11. Cold crucible according to either one of claims 1 or 10, characterised in that the cold finger (or fingers) are constituted of one (or several) heat pipes(s) (60).
12. Cold crucible according to either one of claims 1 or 10, characterised in that the hoop (58) of the direct coil is constituted by continuous assembly of non-electrically insulated heat pipes.
13. Cold crucible according to either one of claims 1 or 10, characterised in that the thick hoop, constituent of the direct coil, is machined for production of heat pipes in situ.

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