WO2018114713A1

WO2018114713A1 - Bottom drain

Info

Publication number: WO2018114713A1
Application number: PCT/EP2017/083140
Authority: WO
Inventors: Manuel NAGEL; Jörg Schollmayer; Rudolf Singer
Original assignee: Umicore Ag & Co.Kg
Priority date: 2016-12-19
Filing date: 2017-12-15
Publication date: 2018-06-28

Abstract

A drainage device for draining molten glass-based fluid from a borehole provided in a base of a container (furnace) containing said molten glass-based fluid, said drainage device having a body comprising : an anchoring element to be connected to an outer surface of a base of the container (furnace), said anchoring element comprising an inlet orifice connected to a first heating circuit; a base element comprising an outlet orifice being connected to a third heating circuit; and a containing element comprising an internal space connected to a second heating circuit, said containing element being placed between said anchoring element and said base element, said anchoring element, base element, and containing element being removably connected to one another, said first, second and third heating circuits being independent from one another.

Description

Bottom drain Field of Invention

The present patent application falls in the domain of drainage of molten glass coming from a molten-glass container, for instance, from a glass-smelting furnace.

In particular, the present invention concerns a drainage device for draining molten glass-based fluid from a borehole provided in a base of a furnace containing said molten glass-based fluid. However, the bottom drain according to the present invention is suitable for being connected to any molten-glass container, including for instance (but not limited to it) a borehole of a refining furnace, a float bath container, forehearth, (float glass) channel, etc.

Background of Invention

It is well-known that during conditioning of (liquefied) molten glass in a (refractory) container, for instance in a (glass-smelting) furnace which is usually placed upstream to a glass forming process such as a float glass (manufacturing) process, materials constituting and coming from the material constituting said furnace, typically ceramic elements from said furnace's walls inner surface (which are directly contacting the molten glass), are expelled out of the inner surface of the furnace's walls and usually precipitate in the molten glass. Said materials are well-known contaminants which impart/depreciate (decrease) the glass quality required for a given (glass forming) application, for instance a float glass manufacturing process.

What is explained here above for the melting furnace is also valid for a refining furnace, a float bath, or any container destined to contain molten-glass in a liquefied form.

Such contaminants can be zircon - forming for instance zircon cords with the molten glass (also known as cat scratches), stone or even brick elements, or even other substances. When accumulated into cords, contaminants usually precipitate onto the base of the furnace.

A drainage device is therefore used for evacuating said precipitated contaminants before they leave the furnace so as to reach the (float) glass forming line, usually driven by a flow of the molten glass from the furnace to the glass forming line. Such a conventional drainage device for draining glass from a borehole provided at a base of a molten-glass container comprises a body having an inlet orifice, to be fluidically connected to the borehole, for allowing a fraction of the molten glass-based fluid comprising undesired substances (impurities such as the contaminants expelled from the container's, for instance a furnace, internal walls, i.e. zirconium-based substances, ceramic bricks and stones, etc., which precipitate into cords of contaminated molten-glass) to flow from the furnace to an internal space of the body arranged to receive said fraction of the molten glass-based fluid comprising undesired substances, said body comprising a heating circuit to be connected to a heating means for heating : i) an inner surface of the inlet orifice, said inlet orifice being suitable for contacting with the fraction of the molten glass-based fluid; and ii) an inner surface defining the internal space of the body, the body further comprising an outlet orifice, fluidically connected to the internal space of the body, for evacuating therethrough said fraction of molten-glass comprising the impurities from the internal space of the body, the outlet orifice comprising an inner surface that is suitable for contacting with the molten glass-based fluid and arranged to be in contact with the molten-glass so as to guide it out of the body.

In such a conventional drainage device, the fraction of molten-glass comprising the impurities is destined to flow under a driving force, in particular it is destined to drain under gravity from the inlet orifice of the body that is (fluidically) connected to furnace to the outlet orifice of the body.

Under operation, for instance, in a float glass process line, wherein a glass-smelting furnace is provided upstream of the line, such a drainage device is used as follows:

Step 1 : the drain device is beforehand installed (usually irreversibly), usually placed under the furnace base: said drain device is connected to an outer surface of the furnace base, so that said outer surface is placed between the drain and the inner surface of the furnace (i.e. an inner surface of the furnace's walls);

Step 2: the furnace is filled with a molten glass-based fluid;

Step 3: during conditioning of the furnace, said furnace being preferably permanently fed in molten glass-based fluid from a feeding inlet point of the furnace and off loaded of said molten glass-based fluid via a offloading point of the furnace (so that a flow of the molten glass-based fluid is created from the inlet to the offload points of the furnace), undesired substances (impurities) are expelled out (washed out) of the inner surface of the furnace's walls and are suspending in the fluid before precipitating on at least a part of an inner surface of the furnace's base so as to form impurity precipitates;

Step 4: during or after precipitation, said impurities in suspension or precipitated are entrained, under the action of the gravity and/or the flow of molten glass in the furnace, through a part of a wall of the base of the furnace via the borehole and through the inlet orifice whose inner surface has been beforehand heated by the heating means to a predetermined temperature and is maintained at said temperature during operation of the drainage device, toward the internal space of the body whose inner surface has been beforehand heated by the heating means to said first predetermined temperature and is maintained at said first predetermined temperature during operation of the drainage device, so as to allow the fluid to flow, under the effect of the gravity, through said internal space and through the outlet orifice of the body toward a recovering container for further treatment (recovering, recycling, conditioning, wasting treatment).

Also, the outlet orifice has its inner surface that can be indirectly heated by the heating means via for instance radiative heating from said heating means.

Operation of the draining device is defined by a period of time between: i) a first moment during which a step where the inlet orifice is heated at the first predetermined temperature [Step 4]; and ii) a second moment during which a step where the inlet orifice is cooled [see Step 5 below]; and

Step 5: after a certain time of use, i.e. a predetermined time during which the float glass process requires an upstream draining of the molten glass (at the molten glass container, i.e. the furnace, level), the heating means is switched off and the inlet orifice providing an access to the body is clogged/obstructed by a fraction of cooled (solidified) molten glass coming from the borehole. Similarly, the internal space is cooled to a predetermined ambient temperature so that another solidified molten glass fraction is created so as to clog the outlet orifice;

In the context of the present invention, Steps 1 - 5 are usual steps of employing a draining device, for instance, in a conventional process line of manufacturing molten glass.

When Step 5 is achieved, using again the draining device, i.e. when a second manufacturing process is operated on the line, implies additional steps which are as follows:

Step 6: unclogging the outlet orifice of the body by melting the cooled glass with the help of an external heating device, usually a burner, so as to create a first access from the internal space to the recovering container, and to optionally remove the cooled glass remaining in the internal space of the body; and Step 7: heating the inner surfaces of the inlet orifice and of the internal space to start the process disclosed in Steps 1 - 5.

Optionally, Step 7 can be effected before or simultaneously to Step 6. When Steps 6 and 7 are achieved, a new loop can be initiated wherein Steps 1 - 5 are performed, each loop corresponding to an operation of the process line requiring drainage upstream.

Form the above-described operational process of the conventional drainage device, several drawbacks are highlighted:

1 °) First, the use of the burner in Step 6 for (re)starting the drainage operation presents a major inconvenient in that this way of cleaning the body of the draining device implies huge thermal constraints to the drain edifice, as a punctual high-energy heat is often required to allow an efficient unclogging of the outlet orifice and of the internal space of the body.

By applying such a located heat on the outlet orifice of the draining device, the thermal constraint induced can, on short to middle-term basis, impair the stability (change in material crystallographic structure of the drain, etc.) of such a draining device (in particular at the level of the outlet orifice), making it obsolete after that several loops of operation of the process line using draining are done. The burner creates material defects of the drain at a region of the outlet orifice;

2°) In addition, when restarting the drain (and applying Step 7), the huge thermal

expansions/constraints resulting from switching on the heating circuit are hindered by the presence of frozen glass coated on the inner surface of the internal space of the body and of the inner surface of the inlet orifice, generating therefore cracks on the body which typically appear on inner surface area(s) of the internal space and/or of the inlet orifice when the drain is restarted.

In particular, when restarting the drain (and applying Step 7), different thermal expansions between a continuous hot inner surface and colder parts around can occur on the drain wall, resulting from switching on the heating circuit. Additionally the presence of frozen glass coated on the inner surface of the internal space of the body and of the inner surface of the inlet orifice can hinder the thermal expansion. This can therefore lead to generating cracks on the body which typically appear on external and/or inner surface area(s) of the internal space and/or of the inlet orifice when the drain is restarted. In case of a direct heated inner surface, these cracks leading to open fissures making the draining device non-operational anymore;

3°) Even more critical: usually, the remaining frozen melted glass from a draining operation is not homogenously coated on the inner surface (of the internal space of the body) of the drain so that by switching on the heating means and heating via the heating circuit the drain inner surfaces (of the inlet and of the internal space) results in over-heating regions of the drain where no glass is present relative to other regions coated with glass. This is an inherent and particular drawback of the drain according to the invention: removing the remaining glass coated on the internal space of the drain implies heating homogenously the inner surfaces of the drain at a temperature that is sufficient to melt the remaining frozen glass; and 4°) The cracks resulting from the heating effected in Step 7 can be propagated into the body of the drainage device, in particular in a core-region of the body, through a body material, usually ceramic, comprised between said core and external surface-regions, leading to internal fissures making the draining device non-operational anymore. In addition, glass can flow out through the inner surface crack and get into contact with the ceramics. Some kinds of ceramics can be damaged/dissolved if they get in contact with the glass-melt.

If such damages are observed, the draining device, when it can be, must be repaired/restored, which means that the draining device has to be temporarily stopped. This is typically done by cooling the drain. In practice, at least two drainage devices are installed perfurnace, so that when one of these devices has to be repaired, at least one spare/reserve draining device can be used. Nevertheless, in this context, the reparation can be unsafe for an operator that will have to work at proximity of the furnace, this operator has therefore to be equipped accordingly to the tough conditions related to such a working environment (warmness, and the inherent danger or hazard present when working in such an environment) plus a restricted space of working which often does not allow full freedom of movement to the operator.

Of course the reparation/restoring option is applicable only when the drain device requires to be repaired. However, if replacement of the body is required, because of the damages that are so huge that reparation becomes unaffordable or technically impossible, the process line should be stopped, and the furnace emptied from the molten-glass. Reason is that replacement of the draining device implies disconnection of the drain of the prior art (and therefore of the inlet orifice of said body), which has been beforehand cooled by switching off the heating means, via the heating circuit, inducing cooling of the inlet orifice and of the internal space of the body, from the borehole which cannot be done in presence of cooled glass in the inlet orifice and borehole of the furnace, i.e. in a region defined between the borehole of the furnace and the inlet orifice of the drain, (that would be indeed detrimental to the efficiency of the replacement process), given that the inlet orifice of the body has to be disconnected from the borehole, which is only possible if no cooled glass is present in a region where said inlet orifice is connected to said borehole. If cooled glass is present in the borehole and further obstructs the inlet orifice, this presence prevents any possibilities of disconnecting the drain body from the furnace base, as cooled glass secures and sticks the base and the body together. Therefore, the only way to replace such a drain is to empty the furnace and the drain from the molten glass, so that such a replacement of the draining device remains onerous and not rentable on large scale application. An even worst problem can occur by removing the drain from the borehole: the whole hot glass would flow out from the furnace and cannot be stopped until the furnace is empty. This is due to the much larger borehole of the furnace which is completely free after removing of the drain and there is no possibility to cooling anymore which can freeze the glass inside of the borehole. There is therefore a need for an alternative to the prior art solution in order to resolve the above- mentioned problems, and in particular, to provide a drainage device having a longer lifespan than the prior art solution, while presenting an easier handling, and therefore being less onerous during use. Summary of Invention

The present invention aims to solve or reduce the abovementioned and other problems by providing a first draining (or drainage) device as above-mentioned in the preamble

characterized in that said body comprises:

an anchoring element made of a first material and to be connected to an outer surface of the base of the molten glass container (for instance the furnace), said anchoring element comprising the inlet orifice which is connected to a first heating circuit, said heating circuit being arranged to be connected to a first heating means for heating an inner surface of said inlet orifice;

a base element made of a second material; and

- a containing element made of a third material and placed between said anchoring

element and said base element, and further comprising said internal space and a second heating circuit connected to the inner surface of said internal space, said base element comprising said outlet orifice having its inner surface connected to a third heating circuit to be connected to a third heating means for heating said inner surface of said outlet orifice, said anchoring element, base element, and containing element being removably connected to one another, said first, second and third heating circuits being independent from one another, so that said first, second and third heating circuits are destined to be heated by the corresponding heating means independently from one another.

The drainage device according to the present invention has the following advantages:

firstly, the presence of a anchoring element that is removably connected to the other elements of the body, and which comprises an independent heating circuit that can be switched on or off independently from the other second and third heating circuits, makes possible to an operator to easily repair or even replace the containing and/or the base elements which can be damaged.

Indeed, during operation of the furnace in a process line and during drainage of the molten glass fluid contained in the furnace, when the operator observe that [(a) part(s) of] the body of the drainage device should be repaired and/or replaced, instead of stopping the process, the operator who wants to handle defects on the drainage device will simply switch off the first heating means, inducing a cooling of the inlet orifice and of the borehole and a hardening of a fraction of the molten glass fluid contained in the borehole and/or in the inlet orifice so as to prevent access of the molten glass in the furnace to the internal space of the containing element.

When access to the containing element is blocked, the operator can handle the damages in the containing element and/or the base elements in safe conditions, for instance by disconnecting these elements from the anchoring element connected to the furnace and by transporting said elements in a secured area for handling, allowing the operator to work in safer conditions, i.e. not in proximity of the furnace, having therefore an unhindered and secured access to the part(s) of the body to be repaired.

Also, should the body be so damaged that it cannot be repaired, the containing and/or the base element(s) can be replaced independently from another. This is made possible because these two elements are removably connected to one another.

A benefit of the present invention resides overwhelmingly in that it allows replacement of (a) damaged part(s) of the body without stopping the process. secondly, the presence of the first to third heating circuits in the body, allows, when a loop of drainage is (re)started, not to use a burner for eventually unclogging the drainage device.

When (re)starting the drainage device, the operator does, in a first step, switch on the third heating means, inducing through the third heating circuit a local heating of the inner surface of the outlet orifice and an eventual melting of cooled glass present in and obstructing said outlet orifice. The inner surface of the outlet orifice is heated and maintained during the drainage operation to a first predetermined temperature T1 , T1 being sufficient so as to allow a fraction of molten glass-based fluid to flow through said outlet orifice so as to be expelled out of the drainage device body.

In a second step, the second heating means is switched on so as to heat the inner surface of the internal space of the body contained in the containing element at a second predetermined temperature T2, allowing an eventual melting of cooled glass present in the internal space of the body, said second predetermined temperature T2 being sufficient for allowing a fraction of molten glass-based fluid to flow from the first inlet orifice to the outlet orifice. Said second predetermined temperature T2 is maintained at a sufficient value for allowing a fraction of molten glass-based fluid to flow from the first inlet orifice to the outlet orifice during the drainage operation.

In a third step, the inner surface of the inlet orifice is heated by (via the first heating circuit connected to) the first heating means to a third predetermined temperature T3 that is sufficient for allowing an eventual melting of cooled glass present in and obstructing said inlet orifice. Said third predetermined temperature T3 is maintained at a sufficient value for allowing a fraction of molten glass-based fluid to flow from the borehole to the internal space of the containing element through said outlet orifice during the drainage operation.

Therefore, it has been observed that the use of a drainage device according to the present invention allows, during drainage operation, that the starting, and in particular the restarting, of the drainage device is better controlled and avoid any intense thermal stresses that can be generated when, for instance, an external burner is used for restarting the drainage device. In particular, the drainage device according to the present invention presents a longer lifespan, versus the conventional drain device, as its use implies de facto less thermal stresses on the body during the (re)starting step: in particular, the mechanical stresses through thermal length elongations are minimized. Stopping the drainage process will imply switching off successively or simultaneously the first, second, and third heating means.

Note that, optionally, the first, second, and third heating means can be switched on/off simultaneously, allowing the operator a full control of the temperature gradient.

Temperatures are included in a range that is for instance from 1200°C - 1600°C, preferably, equal or more than 1 100°C and lower or equal to 1600°C, depending on the molten glass -based liquid to be drained. thirdly, in the framework of the present invention, another advantage of the drainage device according to the present invention is that, under drainage operation, due to the specific design of the drainage body wherein each of elements of the body can be heated independently from one another, a temperature gradient created during

(re)starting of the draining device, from the base element in direction of the anchoring element, can be controlled by the operator so as to be minimized during drainage operation, via adequate settings of T1 , T2 and T3 by controlling independently the first to third heating means.

Surprisingly, it has been observed that, although the fact that the anchoring, containing, and base elements are removably connected one to another, it is possible to minimize the temperature gradient during operation of the drainage device, even if an

intermediate space is present between the anchoring element and the containing element and/or between the containing element and the base element, so that an intermediate gap is eventually created between the inlet orifice of the anchoring element and an access orifice of the internal space of the containing element and/or between an exit orifice of the internal space of the containing element and the outlet orifice of the base element.

When the elements (anchoring, containing and base elements) of the body are removably connected to one another, the operator has the possibility, due to the independency of the first, second and third heating circuit - said circuits being independent one to another - to independently and finely tune the predetermined values of T1 , T2 and T3 so that two adjacent heating circuits generates during operation of the draining process sufficient heat to maintain a desired (minimal) gradient at the interface between two adjacent elements, so that the temperature profile can be continuous, even at a region were an intermediate space/gap is present between two adjacent elements. Other details and advantages of the present invention will become apparent from the description hereunder of preferred and non-limitative embodiments of the drainage device according to the invention:

Embodiment 1

In a first embodiment of the drainage device according to the invention, the first heating circuit directly and/or indirectly connected to the inner surface of the inlet orifice of the anchoring element. An indirect heating has the following advantage: with a heating circuit which is indirectly connected to the inner surface of the inlet orifice, effectiveness of the heating is not impaired by an eventual crack in the anchoring element material that would cut a contact which is present (i.e. when said heating circuit and inner surface are directly connected one to another) between the inner surface and the heating circuit.

Embodiment 2

In a second embodiment of the drainage device according to the invention, the second heating circuit is directly and/or indirectly connected to the inner surface of the internal space of the containing element.

Embodiment 3

In a third embodiment of the drainage device according to the invention, the third heating circuit is directly and/or indirectly connected to the inner surface of the outlet orifice of the base element.

Embodiment 4

In a fourth embodiment of the drainage device according to the invention, the inner surface of the internal space of the containing element is corrugated and formed by a series of valleys and ridges.

Embodiment 5

In a fifth embodiment of the drainage device according to the invention, the containing element comprises a (preferably cylindrical) conduit made of at least one metal selected from the group of platinum metals (so-called PMG [Platinum-Metal-Group] group), said conduit being arranged to be fluidically connected to the inlet and outlet orifices, said internal space of the containing element being defined by an inner space of the conduit and said inner surface of the containing element being defined by an inner surface of the conduit.

In particular, the hollow conduit is a hollow tube (of the containing element) or a cylindrical- shaped conduit.

Optionally, the hollow conduit has its inner surface that is corrugated and presents a series of valleys and ridges. The valleys are oriented in direction of the internal space of the containing element. The ridges are oriented in a direction opposite to the orientation direction of the valleys. A corrugated surface allows to better compensate the thermal expansion of the inner surface material during use of the drain. Corrugations allow to offset the deformation of the inner surface length of the hollow conduit when contacting the molten glass and subjected to thermal constraints. In a preferable embodiment of the Embodiment 5 of the drainage device according to the invention, said valleys and said ridges are parallel to one other and arranged so that a valley is intercalated between two ridges.

Embodiment 6

In a sixth embodiment of the drainage device according to the invention, the anchoring element comprises a duct fluidically connected to the inlet orifice, said duct being arranged to be

(preferably irreversibly) inserted during glass manufacturing (i.e. when the furnace comprises glass in a molten state) in an inner space of the borehole of the furnace so as to be anchored to the furnace.

Optionally, said duct is directly and/or indirectly connected to the first heating circuit and is therefore arranged to be (preferably directly and/or indirectly) heated by said first heating circuit.

In a specific embodiment of the Embodiment 6 of the drainage device, the duct is made of at least one metal selected from the PMG group.

Embodiment 7

In a seventh embodiment of the drainage device according to the invention, the base element of the body included in the drainage device according to the invention comprises a nozzle fluidically connected to said outlet orifice of the base element, said nozzle being arranged to be crossed by the molten glass-based fluid. In particular, the nozzle is directly connected to the third heating circuit, so that the third heating circuit is arranged to directly heat the nozzle.

Preferably, the nozzle has a hollow conical shape, having a first open end fluidically connected to the internal space of the containing element and defined by a first opening surface S1 and a second open end, opposite to the first open end, and defined by a second opening surface S2.

In particular, the nozzle has a funnel shape, so that the second open end is extended by a hollow tube (of the nozzle).

Embodiment 8

In an eighth embodiment of the drainage device according to the invention, the first heating circuit is indirectly and/or indirectly connected to the duct and the inner surface of the first orifice.

Optionally, the first heating circuit is indirectly and/or directly connected to the duct or to the inner surface of the first orifice.

In this Embodiment 8 of the drainage device according to the invention, said duct and first heating circuit are preferably at least partially encased into said anchoring element.

Preferably, said duct and said inner surface of the inlet orifice are separated from at least a part of the first heating circuit by the first material of said anchoring element, so that the first heating circuit is arranged to indirectly heat the duct and the inner surface of the inlet orifice.

Optionally, said duct or said inner surface of the inlet orifice are separated from at least a part of the first heating circuit by the first material of said anchoring element, so that the first heating circuit is arranged to indirectly heat the duct or the inner surface of the inlet orifice. Embodiment 9

In a ninth embodiment of the drainage device according to the invention, the second heating circuit is indirectly and/or directly connected to the inner surface of the internal space of the containing element of the body, said second heating circuit being preferably at least partially encased in said containing element of the body element. Optionally, the inner surface of the internal space of the containing element of the body and at least a part of the second heating circuit being separated from each other by the third material of said body element, so that the second heating circuit is arranged to indirectly heat the inner surface of the internal space. Embodiment 10

In a tenth embodiment of the drainage device according to the invention, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the duct and the inner surface of the inlet orifice, the duct and the inner surface of the inlet orifice being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element.

Alternatively, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the duct or the inner surface of the inlet orifice, the duct or the inner surface of the inlet orifice being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element.

Embodiment 11

In a eleventh embodiment of the drainage device according to the invention, when said base element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice and to the nozzle, the inner surface of the outlet orifice and the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element and said containing element.

Alternatively, when said base element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice or to the nozzle, the inner surface of the outlet orifice or the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element or said containing element.

Embodiment 12

In a twelfth embodiment of the drainage device according to the present invention, the first, second, and third materials comprise ceramic, preferably firebricks ceramic, more preferably mullite ceramic and silicon oxide-based material.

Embodiment 13

In a thirteenth embodiment of the drainage device according the present invention, the first, second, and third heating circuits are made, at least partially, of a thermally conductive material and are arranged to be connected to a heat generator destined to generate heat to be distributed independently by the first, second and third heating circuits.

Embodiment 14

In a fourteenth embodiment of the drainage device according the present invention, the first, second, and third heating circuits are made, at least partially, of an electrically resistant material for converting an electric current into heat, and are arranged to be connected to an electric current generator destined to generate an electric current to be converted independently by the first, second and third heating circuits into heat.

Embodiment 15

In a fifteenth embodiment of the drainage device according to the invention, the first, second, and third heating circuits are made of at least one metal of the PMG of metals. Embodiment 16

In a sixteenth embodiment of the drainage device according to the invention, the inner surface of the inlet opening, the inner surface of the internal space, and the inner surface of the outlet orifice are covered, at least partially, by a covering material comprising at least one metal chosen from the PMG group of metals.

Optionally, the inner surface of the inlet opening is covered, at least partially, by a first covering material comprising at least one metal chosen from the PMG group of metals, said first covering material being directly and/or indirectly connected to the first heating circuit. Preferably, the inner surface of the internal space is, at least partially, covered by a second covering material comprising at least one metal chosen from the PMG group of metals, said second covering material being directly and/or indirectly connected to the second heating circuit. More preferably, the inner surface of the outlet orifice is covered by a third covering material comprising at least one metal chosen from the PMG group of metals, said second covering material being directly and/or indirectly connected to the third heating circuit.

Each of the individual drainage device Embodiments 1 to 16 described hereabove may be combined with one or more of the drainage device embodiments described before it. The present invention also covers an anchoring element (or anchoring device) of the drainage device according to the invention, said anchoring element being made of a first material and arranged to be connected to an outer surface of a base of a furnace, said anchoring element comprising a first heating circuit to be connected to a first heating means for heating an inner surface of an inlet orifice of the anchoring element to be fluidically connected to a borehole presents on the base of the furnace and to be fluidically connected to an internal space of an containing element, said anchoring element being arranged to be removably connected to the containing element of the drainage device according to the invention which comprises the internal space and a second heating circuit to be connected to a second heating means for heating an inner surface of the internal space, said first and second heating circuits being independent to one another when said anchoring element and said containing elements are connected together.

Other details and advantages of the anchoring element included in the present invention will become apparent from the description hereunder of preferred and non-limitative embodiments of the anchoring element according to the invention:

Embodiment 1

In a first embodiment of the anchoring device according to the invention, the first heating circuit is directly and/or indirectly connected to the inner surface of the inlet orifice of the anchoring element.

Embodiment 2

In a second embodiment of the anchoring device according to the invention, the anchoring element comprises a duct fluidically connected to the inlet orifice, said duct being arranged to be (preferably irreversibly) inserted in an inner space of the borehole of the furnace so as to be anchored to the furnace.

Optionally, said duct is directly and/or indirectly connected to the first heating circuit and is therefore arranged to be (preferably directly and/or indirectly) heated by said first heating circuit. In a specific embodiment of the Embodiment 2 of the anchoring device according to the present invention, the duct is made of at least one metal selected from the PMG group.

Embodiment 3

In a third embodiment of the anchoring device according to the invention, the first heating circuit is indirectly connected to the duct and the inner surface of the first orifice. Optionally, the first heating circuit is indirectly connected to the duct or to the inner surface of the first orifice

In this Embodiment 3 of the anchoring device according to the present invention, said duct and first heating circuit are preferably at least partially encased into said anchoring element.

Optionally, said duct or said inner surface of the inlet orifice are separated from at least a part of the first heating circuit by the first material of said anchoring element, so that the first heating circuit is arranged to indirectly heat the duct or the inner surface of the inlet orifice. Embodiment 4

In a fourth embodiment of the anchoring device according to the present invention, the first material comprises ceramic.

Embodiment 5

In a fifth embodiment of the anchoring device according to the present invention, the first heating circuit is made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the first heating circuit. Embodiment 6

In a sixth embodiment of the anchoring device according to the present invention, the first heating circuit is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the first heating circuit into heat.

Embodiment 7

In a seventh embodiment of the anchoring device according to the invention, the first heating circuit is made of at least one metal of the PMG of metals. Embodiment 8

In an eighth embodiment of the anchoring device according to the invention, the inner surface of the inlet opening and/or of the duct is covered, at least partially, by a covering material comprising at least one metal chosen from the PMG group of metals.

In particular, the duct is made, at least partially, of at least one PGM-based material.

Optionally, the inner surface of the inlet opening is covered, at least partially, by a first covering material comprising at least one metal chosen from the PMG group of metals, said first covering material being directly and/or indirectly connected to the first heating circuit.

Each of the individual anchoring device (anchoring element) Embodiments 1 to 8 described hereabove may be combined with one or more of the anchoring element embodiments described before it. The present invention also claims a containing element of the drainage device according to the invention, said containing element being made of a third material and being arranged to be removably connected to an anchoring and to a base elements of the drainage device according to the invention, so as to be interposed between said anchoring and base elements, said containing element comprising an internal space to be fluidically connected to an inlet orifice of the anchoring element and to an outlet orifice of the base element, said containing element comprising a second heating circuit connected to an inner surface of the internal space, said second heating circuit being arranged to be connected to a second heating means for heating the inner surface of the internal space, said second heating circuit, a first heating circuit of the anchoring element and a third heating circuit of the base element, being independent to one another when said containing element, said anchoring element, and said base element are connected together.

Other details and advantages of the containing element included in the present invention will become apparent from the description hereunder of preferred and non-limitative embodiments of the containing element according to the invention:

Embodiment 1

In a first embodiment of the containing element according to the invention, the second heating circuit is directly and/or indirectly connected to the inner surface of the internal space of the containing element. Embodiment 2

In a second embodiment of the containing element according to the invention, the inner surface of the internal space is corrugated and formed by a series of valleys and ridges. Embodiment 3

In a third embodiment of the containing element according to the invention, the containing element comprises a (preferably cylindrical) conduit made of at least one metal selected from the group of platinum metals (so-called PMG [Platinum-Metal-Group] group), said conduit being arranged to be fluidically connected to the inlet and outlet orifices, said internal space of the containing element being defined by an inner space of the conduit and said inner surface of the containing element being defined by an inner surface of the conduit.

Optionally, the hollow conduit has its inner surface that is corrugated and presents a series of valleys and ridges. The valleys are oriented in direction of the internal space of the containing element. The ridges are oriented in a direction opposite to the orientation direction of the valleys.

In a preferable embodiment of the Embodiment 3 of the containing element, said valleys and said ridges are parallel to one other and arranged so that a valley is intercalated between two ridges.

Embodiment 4

In a fourth embodiment of the containing element according to the invention, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to a duct and an inner surface of the inlet orifice of the anchoring element, the duct and the inner surface of the inlet orifice being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element.

Alternatively, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to a duct or an inner surface of the inlet orifice of the anchoring element, the duct or the inner surface of the inlet orifice of the anchoring element being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element. Embodiment 5

In a fifth embodiment of the containing element according to the invention, when said base element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice of the base element and to a nozzle of the base element, the inner surface of the outlet orifice and the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element and said containing element. Alternatively, when said base element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice or to a nozzle of the base element, the inner surface of the outlet orifice or the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element or said containing element.

Embodiment 6

In a sixth embodiment of the containing element according to the present invention, the third material comprises ceramic.

Embodiment 7

In a seventh embodiment of the containing element according to the present invention, the second heating circuit is made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the second heating circuit.

Embodiment 8

In an eight embodiment of the containing element according to the present invention, the second heating circuit is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the second heating circuit into heat.

Embodiment 9

In a ninth embodiment of the containing element according to the invention, the second heating circuit is made of at least one metal of the PMG of metals. Embodiment 10

In a tenth embodiment of the containing element according to the invention, the inner surface of the internal space is covered, at least partially, by a covering material comprising at least one metal chosen from the PMG group of metals.

Optionally, the inner surface of the internal space is covered, at least partially, by a second covering material comprising at least one metal chosen from the PMG group of metals, said second covering material being directly and/or indirectly connected to the second heating circuit.

Each of the individual containing element Embodiments 1 to 10 described hereabove may be combined with one or more of the containing element embodiments described before it.

The present invention also concerns a base element of the drainage device according to the invention made of a second material and arranged to be removably connected to a containing element of the drainage device according to the invention, said base element comprising an outlet orifice to be fluidically connected to an internal space of the containing element, said base element comprising a third heating circuit connected to an inner surface of the outlet orifice, said third heating circuit being arranged to be connected to a third heating means for heating the inner surface of the outlet orifice, said third heating circuit of the base element, a second heating circuit of the containing element being independent to one another when said containing element and said base element are connected together.

Other details and advantages of the base element included in the present invention will become apparent from the description hereunder of preferred and non-limitative embodiments of the base element according to the present invention:

Embodiment 1

In a first embodiment of the base element according to the present invention, the third heating circuit is directly and/or indirectly connected to the inner surface of the outlet orifice of the base element.

Embodiment 2

In a second embodiment of the base element according to the present invention, the base element includes a nozzle fluidically connected to said outlet orifice of the base element, said nozzle being arranged to be crossed by the molten glass-based fluid. In particular, the nozzle is directly connected to the third heating circuit, so that the third heating circuit is arranged to directly heat the nozzle.

Preferably, the nozzle has a hollow conical shape, having a first open end to be fluidically connected to the internal space of the containing element and defined by a first opening surface S1 and a second open end, opposite to the first open end, and defined by a second opening surface S2.

Optionally, the nozzle is at least partially encased in the second material of the base element.

Embodiment 3

In a third embodiment of the base element according to the present invention, the second material comprises ceramic.

Embodiment 4

In a fourth embodiment of the base element according to the present invention, the third heating circuit is made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the third heating circuit.

Embodiment 5

In an fifth embodiment of the base element according to the present invention, the third heating circuit is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the third heating circuit into heat. Embodiment 6

In a sixth embodiment of the base element according to the invention, the third heating circuit is made of at least one metal of the PMG of metals.

Embodiment 7

More preferably, in a 7^th embodiment of the base element according to the invention, the inner surface of the outlet orifice is covered by a third covering material comprising at least one metal chosen from the PMG group of metals, said second covering material being directly and/or indirectly connected to the third heating circuit

Each of the individual base element Embodiments 1 to 7 described hereabove may be combined with one or more of the containing element embodiments described before it.

The present invention is also inclusive of a kit-of-parts comprising:

i) an anchoring element of the drainage device according to the invention, said

anchoring element being made of a first material and arranged to be connected to an outer surface of a base of a furnace, said anchoring element comprising an inlet orifice to be fluidically connected to a borehole presents on the base of the furnace and to fluidically connected to an internal space of a containing element, and a first heating circuit to be connected to a first heating means for heating an inner surface of the inlet orifice;

ii) a base element of the drainage device according to the invention made of a second material, said base element comprising an outlet orifice to be fluidically connected to an internal space of the containing element, said base element comprising a third heating circuit connected to an inner surface of the outlet orifice, said third heating circuit being arranged to be connected to a third heating means for heating the inner surface of the outlet orifice; and

iii) a containing element of the drainage device according to the invention, said

containing element being made of a third material and being arranged to be removably connected to the anchoring and to the base elements of the drainage device according to the invention, so as to be interposed between said anchoring and base elements, said containing element comprising an internal space to be fluidically connected to the inlet orifice of the anchoring element and to the outlet orifice of the base element, said containing element comprising a second heating circuit connected to an inner surface of the internal space

, said parts i), ii) and iii) being arranged to be (removably) assembled to form the body of the drainage device according to the present invention, said first heating circuit of the anchoring element and said third heating circuit of the base element, being independent to one another when said containing element, said anchoring element, and said base element are connected together.

Other details and advantages of the kit-of-parts included in the present invention will become apparent from the description hereunder of preferred and non-limitative embodiments of the kit- of-parts according to the invention, preferably when said parts i), ii) and iii) are removably connected one another so as to form the body of the drainage device according to the present invention: Embodiment 1

In a first embodiment of the kit-of-parts according to the invention, the first heating circuit is directly and/or indirectly connected to the inner surface of the inlet orifice of the anchoring element. Embodiment 2

In a second embodiment of the kit-of-parts according to the invention, the second heating circuit is directly and/or indirectly connected to the inner surface of the internal space of the containing element. Embodiment 3

In a third embodiment of the kit-of-parts according to the invention, the third heating circuit is directly and/or indirectly connected to the inner surface of the outlet orifice of the base element.

Embodiment 4

In a fourth embodiment of the kit-of-parts according to the invention, the inner surface of the internal space is corrugated and formed by a series of valleys and ridges.

Embodiment 5

In a fifth embodiment of the kit-of-parts according to the invention, the containing element comprises a (preferably cylindrical) conduit made of at least one metal selected from the group of platinum metals (so-called PMG [Platinum-Metal-Group] group), said conduit being fluidically connected to the inlet and outlet orifices, said internal space of the containing element being defined by an inner space of the conduit and said inner surface of the containing element being defined by an inner surface of the conduit.

In a preferable embodiment of the Embodiment 5 of the kit-of-parts, said valleys and said ridges are parallel to one other and arranged so that a valley is intercalated between two ridges.

Embodiment 6

In a sixth embodiment of the kit-of-parts according to the invention, the anchoring element comprises a duct fluidically connected to the inlet orifice, said duct being arranged to be

(preferably irreversibly) inserted in an inner space of the borehole of the furnace so as to be anchored to the furnace.

In a specific embodiment of the Embodiment 6 of the kit-of-parts, the duct is made of at least one metal selected from the PMG group.

Embodiment 7

In a seventh embodiment of the kit-of-parts according to the invention, the base element of the body included in the kit-of-parts according to the invention comprises a nozzle fluidically connected to said outlet orifice of the base element, said nozzle being arranged to be crossed by the molten glass-based fluid. In particular, the nozzle is directly connected to the third heating circuit, so that the third heating circuit is arranged to directly heat the nozzle.

In particular, the nozzle has a funnel shape, so that the second open end is extended by a hollow tube (of the nozzle). Embodiment 8

In an eighth embodiment of the kit-of-parts according to the invention, the first heating circuit is indirectly connected to the duct and the inner surface of the first orifice. Optionally, the first heating circuit is indirectly connected to the duct or to the inner surface of the first orifice.

In this Embodiment 8 of the kit-of-parts according to the invention, said duct and first heating circuit are preferably at least partially encased into said anchoring element.

Preferably, said duct and said inner surface of the inlet orifice are separated from at least a part of the first heating circuit by the first material of said anchoring element, so that the first heating circuit is arranged to indirectly heat the duct and the inner surface of the inlet orifice. Optionally, said duct or said inner surface of the inlet orifice are separated from at least a part of the first heating circuit by the first material of said anchoring element, so that the first heating circuit is arranged to indirectly heat the duct or the inner surface of the inlet orifice.

Embodiment 9

In a ninth embodiment of the kit-of-parts according to the invention, the second heating circuit is indirectly and/or directly connected to the inner surface of the internal space of the containing element of the body.

The second heating circuit is preferably at least partially encased in said containing element of the body element, and the inner surface of the internal space of the containing element of the body and at least a part of the second heating circuit being separated from each other by the third material of the containing element of the body element, so that the second heating circuit is arranged to indirectly heat the inner surface of the internal space. Embodiment 10

In a tenth embodiment of the kit-of-parts according to the invention, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the duct and the inner surface of the inlet orifice, the duct and the inner surface of the inlet orifice being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element. Alternatively, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the duct or the inner surface of the inlet orifice, the duct or the inner surface of the inlet orifice being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element.

Embodiment 11

In a eleventh embodiment of the kit-of-parts according to the invention, when said base element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice and to the nozzle, the inner surface of the outlet orifice and the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element and said containing element. Alternatively, when said base element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice or to the nozzle, the inner surface of the outlet orifice or to the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element or said containing element.

Embodiment 12

In a twelfth embodiment of the kit-of-parts according to the present invention, the first, second, and third materials comprise ceramic.

Embodiment 13

In a thirteenth embodiment of the kit-of-parts according the present invention, the first, second, and third heating circuits are made, at least partially, of a thermally conductive material and are arranged to be connected to a heat generator destined to generate heat to be distributed by the first, second and third heating circuits.

Embodiment 14

In a fourteenth embodiment of the kit-of-parts according the present invention, the

the first, second, and third heating circuits are made, at least partially, of an electrically resistant material for converting an electric current into heat, and are arranged to be connected to an electric current generator destined to generate an electric current to be converted by the first, second and third heating circuits into heat. Embodiment 15

In a 15^th embodiment of the kit-of-parts according to the invention, the first, second, and third heating circuits are made of at least one metal of the PMG of metals. Embodiment 16

In a 16^th embodiment of the kit-of-parts according to the invention, the inner surface of the inlet opening, the inner surface of the internal space, and the inner surface of the outlet orifice are covered, at least partially, by a covering material comprising at least one metal chosen from the PMG group of metals.

Each of the individual kit-of-parts Embodiments 1 to 16 described hereabove may be combined with one or more of the kit-of-parts embodiments described before it.

In the context of the present invention, the term "PMG" must be understood as the Platinum- Metal-Group, a group mainly comprising at least one of the following elements: ruthenium, rhodium, palladium, osmium, iridium, and platinum.

In the context of the present invention, the terms "directly connected" or "indirectly connected" refer to two or more entities which are respectively connected to one another by respectively contacting each other (i.e. direct connection), or are subjected to a contact-free connexion (i.e. indirect connection). For instance, but not limited to this example: in a preferred embodiment of the invention wherein the first heating circuit, arranged to be connected to a first heating means, that is indirectly connected to a first entity (for instance the duct of the anchoring element), said first circuit is separated from the duct by a buffer region (for instance the [first] material of the anchoring element). Said duct does therefore not contact with said first heating circuit, so that, when the first heating means is switched on, the heat conducted by said first heating circuit is transferred indirectly through the (first) material, for instance by a heat radiation and/or a heat conduction mechanism(s), to the duct.

When heating is performed indirectly, via said heat radiation and/or a heat conduction mechanism(s), it is preferable that the buffer material (which can be a material constituting the drain [if a clearance is separating the heating circuit from an element to be heated indirectly [for instance the duct of the anchoring element]) is a heat conductor and/or infra-red radiation conductor material.

In another preferred embodiment of the invention wherein the third heating circuit, arranged to be connected to a third heating means, is directly connected to a second entity (i.e. the nozzle of the base element), said second entity does contact with the third heating circuit so that, when the third heating means is switched on, the heat conducted by said third heating circuit is directly transferred to the second entity via at least one contact point between said third heating circuit and the second entity.

In the context of the present invention, the terms "said first, second and third heating circuits being independent from one another" means that the second, first and third heating circuits can be heated independently from one another.

In the context of the present invention, the terms "fluidically connected" means that a connexion is created so that it allows a fluid to flow through said connexion. A fluidical connexion can be hermetic or non-hermetic.

Brief Description of the Figures

In order to explain the invention; a non-limiting example of a specific embodiment of a drain according to the invention and its use is given below, with reference to the following figures: figure 1 shows an exploded view of a first embodiment of a body of the draining device according to the invention, and figure 2 depicts a view of another embodiment of a body of the draining device according to the invention wherein an anchoring element of the invention, a containing element of the invention, and a base element are assembled so as to form said body. figure 3 shows a view of an alternative embodiment of a body of the draining device according to the invention wherein an anchoring element of the invention and a base element are assembled so as to form said body. Detailed Description

Figure 1 shows an exploded view of a body 1 of the draining device 2 according to the invention.

The body 1 comprises an anchoring element 3, a containing element 4 (or container), and a base element 5.

These elements (anchoring, containing and base elements) are removably connected to one another by a first screw-nut system. The terms "removably connected" mean here "connected in a removable way".

In the exploded view depicted in figure 1 , it is shown that the containing element 4 is arranged to be fixed to the anchoring element 1 and to the base element 5 so as to be interposed between these anchoring and base elements.

Figure 2 shows a cross sectional view of the body of figure 1 wherein the anchoring, the containing and the base element are connected to one another, so as to form the body according to the present invention. In figure 2, the base element is placed at a first level L0 which is a reference (horizontal) level, for instance the floor/ground level. The base of the furnace is at a second level L1 , at a first (vertical) height H1 from the level HO. The anchoring element is disposed between the base element and the furnace. The anchoring element is placed so as to be at a second (vertical) height H2 (height measured vertically between L0 and a third level L2 on which said anchoring element relies) which is inferior to H1. The containing element is placed between the anchoring and the base elements and relies on a third (horizontal) level L3 at a third (vertical) height HO for the ground.

The cross section depicted in figure 2 is a longitudinal cross section, in a direction from the base element 5 to the anchoring element 3. The anchoring element 3 of the drainage device according to the invention is made of a first material 10, preferably a ceramic material.

This anchoring element 3 is arranged to be connected to an outer surface 1 1 of a base of a molten glass container such as a furnace 12 (not shown in figure 1 ).

As depicted in figure 1 , the anchoring element 3 is also arranged to be removably connected to the containing element 4 via a second screw-nut system; and the base element is arranged to be removably connected to the containing element 4 via a third screw-nut system

The anchoring element 3 comprises an inlet orifice 6 to be fluidically connected to a borehole 13 presents on the base 1 1 of the furnace 12 and crossing through the base of said furnace (not show in figure 1 ). A duct 7, included in the anchoring element 3 and fluidically connected to the inlet orifice 6, is arranged to be fluidically connected to an internal space 8 of the containing element 4.

The anchoring element further comprises a first heating circuit HC1 to be connected to a first heating means (not shown in figures 1 and 2) for heating an inner surface 14 of the inlet orifice.

The first heating circuit HC1 is connected to the inner surface 14 of the inlet orifice 6 and to the duct 7 which is therefore arranged to be heated by said first heating circuit HC1.

The first heating circuit HC1 is preferably indirectly connected to the duct 7 and the inner surface of the first orifice. In such an arrangement, the duct and first heating circuit may be in at least partially encased into the anchoring element. For instance, the duct and the inner surface of the inlet orifice can be separated from the first heating circuit HC1 by the first material 10 of the anchoring element 2, so that the first heating circuit is arranged to indirectly heat the duct and the inner surface of the inlet orifice.

In the particular (and non-limitative) embodiment of the body depicted in figure 1 , the first heating circuit HC1 comprises an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate the electric current to be converted by the first heating circuit into heat. A suitable material for composing the electrically resistant material can be at least one metal of the PMG of metals. So as to allow heat to be transferred from the first heating circuit HC1 to the inner surface of the inlet opening, said inner surface of the inlet opening can be covered, at least partially, by a first covering material comprising at least one metal chosen from the PMG group of metals, said first covering material being indirectly connected to the first heating circuit HC1. The duct can also be made of at least one metal selected from the PMG group, so that heat transfer is improved.

When the duct and the inner surface of the inlet orifice are indirectly connected to the first heating circuit HC1 , the duct and the inner surface of the inlet orifice are arranged to be heated by heat radiation and/or heat conduction from the first heating circuit through the ceramic material of the anchoring element. In this particular embodiment, it is preferred that the first material separating the duct and the inner surface of the inlet orifice from the first heating circuit is made of a heat conductor material.

When the heating source of the first heating circuit HC1 , and to which the first heating circuit has been beforehand connected, the first heating circuit heats the inner surface of the duct and/or of the inlet orifice, and it results that the heat of said inner surface, when contacting the molten glass coming from the borehole, is transferred from the first heating circuit via the inner surface (of the duct and/or of the inlet orifice) to the molten glass, keeping said molten glass in a molten stat, allowing it to flow in direction of the outlet orifice of the draining device. The heat transfer from the inner surface of the duct and/or of the inlet orifice can also be ensured by radiative heating of the molten glass, so that said molten glass can be kept under its molten phase without contacting the inner surface of the duct and/or the inlet orifice.

The containing element 4 is made of a third material 4a that can be for instance ceramic.

The containing element 4 is arranged to be removably connected to the anchoring 3 and to the base elements 5, so as to be interposed between the anchoring and the base elements.

The containing element 4 comprises an internal space 8 to be fluidically connected to the inlet orifice 6 of the anchoring element 3 (via the duct 7 of the anchoring element) and to an outlet orifice 9 of the base element 5.

The containing element 4 comprises a second heating circuit HC2 directly connected to an inner surface 16 of the internal space 15. The second heating circuit is arranged to be connected to a second heating means (not depicted in figures 1 and 2) for heating the inner surface 16 of the internal space 15. When the anchoring element 3 is connected to the containing element 4, a clearance is preferably formed between a base B1 of the anchoring element facing a frontal face F1 of the containing element (see Figure 1 ), so as to prevent mechanical constraints on each of the anchoring and containing elements when the first and second heating circuit are operating, due to the thermic dilatation/expansion of these elements.

As shown in figure 2, the inner surface 16 of the internal space 8 is corrugated. The corrugated inner surface comprises a series of valleys 17 and ridges 18. In the specific embodiment depicted in figure 2, the containing element 4 comprises a

(preferably cylindrical) conduit made of at least one metal selected from the group of platinum metals (so-called PMG [Platinum-Metal-Group] group). The conduit encased in the containing element is fluidically connected to the inlet 6 and outlet 9 orifices. The internal space 8 of the containing element 4 is defined by an inner space of the conduit 15 and the inner surface 16 of the containing element is defined by an inner surface of the conduit 15.

In particular, the hollow conduit 15 is a hollow tube (of the containing element) or a cylindrical- shaped conduit. Optionally, the hollow conduit 15 has its inner surface that is corrugated. The inner surface of the conduit 15 may present a series of valleys 17 and ridges 18. The valleys are preferably oriented in direction of the internal space of the containing element. The ridges are preferably oriented in a direction opposite to the orientation direction of the valleys. Optionally, when the anchoring element 3 is removably connected to said containing element 4, the second heating circuit HC2 is arranged so as to be directly connected to the duct 7 and the inner surface 14 of the inlet orifice 6.

Also, when the base element 5 is removably connected to the containing element 3, the second heating circuit HC2 is arranged so as to be indirectly connected to an inner surface 20 of the outlet orifice 9 of the base element and to a nozzle 21 , fluidically connected to the outlet orifice, the inner surface 20 of the outlet orifice 9 and the nozzle 21 being preferably separated from at least a part of the second heating circuit by the third material of the containing element (and/or the second material of the base element) and/or by a second intermediate space formed between said base element and said containing element. In such a case, the nozzle and the inner surface of the outlet orifice are arranged to be indirectly heated via heating radiation from the second heating circuit HC2 of the containing element 4. Indirect heating of the nozzle by the second heating circuit HC2 is for instance made possible by an optional embodiment of the containing element which presents a niche wherein the nozzle can be lodged/encased so as to be surrounded by at least a part of the second heating circuit, a part of the third material of the containing element being present between said nozzle and said second heating circuit. This is an optional embodiment to permit indirect heating of the nozzle via the HC2 circuit. In such a case, the temperature gradient between the containing element and the base element is ensured to be constant and minimized. Preferably, between the containing element and the base element, the temperature gradient is minimized so that the heat loss through radiation to the ambient is minimized.

Optionally, having a thermally insulating third material is preferred so that the direct heating is not dissipated from the internal space of the containing element to an outer region of the containing element. Also, at least a first part of the third material is suitable for allowing the second heating means HC2 to indirectly heat the outlet orifice and/or the nozzle of the base element when the containing element and the base elements are connected together. Similarly, at least a second part of the third material is suitable for allowing the second heating means HC2 to indirectly heat the inlet orifice and/or the duct of the anchoring element when the containing element and the anchoring elements are connected together. The second heating circuit is preferably made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the second heating circuit.

The second heating circuit can also be made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the second heating circuit into heat.

A second heating circuit made of at least one metal chosen from the PMG of metals can satisfy the electrically resistant condition and/or the thermally conduction to allow direct heating of the inner surface 16 of the internal space or internal (open) cavity 8 of the containing element.

Similarly, a second heating circuit made of at least one metal chosen from the PMG of metals can satisfy the electrically resistant condition and/or the thermally conduction to allow indirect heating of the nozzle and the inner surface of the outlet orifice and/or the duct and the inner surface of the inlet orifice. In particular, the inner surface 16 of the internal space 8 is covered, at least partially, by a second covering material comprising at least one metal chosen from the PMG group of metals. This second covering material is directly connected to the second heating circuit HC2. When the heating source of the second heating circuit HC2, and to which the second heating circuit has been beforehand connected, the second heating circuit heats the inner surface of the internal space of the containing element, and it results that the heat of said inner surface, when contacting the molten glass coming from the inlet orifice, is transferred from the second heating circuit via the inner surface (of the internal space) to the molten glass, keeping said molten glass in a molten stat, allowing it to flow in direction of the outlet orifice of the draining device. The heat transfer from the inner surface of the internal space can also be ensured by radiative heating of the molten glass, so that said molten glass can be kept under its molten phase without contacting the inner surface of the internal space. The base element 5 has a third heating circuit HC3 that is directly and/or indirectly connected to the inner surface 20 of its outlet orifice 9.

Also, the base element has a nozzle 21 that may be directly connected to the third heating circuit, so that the third heating circuit is arranged to directly heat the nozzle. The base element is made of a second material that can be for instance ceramic, like mullite ceramic, or even preferably firebricks, and which is preferably a heat insulator material. The nozzle is preferably encased, at least partially, in the base element. In particular, the nozzle has a funnel shape, so that the second open end is extended by a hollow tube (of the nozzle) in the base element. Said hollow tube having an end opening to be connected with an outside of the draining device. In particular, the end opening of the hollow tube of the funnel-shaped nozzle is to be connected with a recovering container arranged to be disposed under the base element, so as to be place between the ground (level L0) and the base element (level L3).

When the base and the containing elements are (removably) connected, the nozzle is preferably (at least partially) encased in an open cavity that is present in the containing element. When the containing element is removably connected to the base element, the nozzle is encased in the open cavity of the containing element and fluidically connected to the internal space of the containing element. Preferably, the nozzle has a hollow conical shape, having a first open end arranged to be fluidically connected to the internal space 8 of the containing element 4 and defined by a first opening surface S1 and a second open end, opposite to the first open end, and defined by a second opening surface S2.

The third heating circuit HC3 of the base element is preferably made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the third heating circuit.

Alternatively, the third heating circuit HC3 is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the third heating circuit into heat.

Optionally, the third heating circuit is made of at least one metal of the PMG of metals. When the heating source of the third heating circuit HC3, and to which the third heating circuit has been beforehand connected, the third heating circuit heats the inner surface of the nozzle and/or of the outlet orifice, and it results that the heat of said inner surface, when contacting the molten glass coming from the borehole, is transferred from the third heating circuit via the inner surface (of the nozzle and/or of the outlet orifice) to the molten glass, keeping said molten glass in a molten stat, allowing it to flow in direction of the outside of the draining device. The heat transfer from the inner surface of the nozzle and/or of the outlet orifice can also be ensured by radiative heating of the molten glass, so that said molten glass can be kept under its molten phase without contacting the inner surface of the nozzle and/or the outlet orifice. When said containing element, said anchoring element, and said base element are removably connected together, the second heating circuit of the containing element, the first heating circuit of the anchoring element and the third heating circuit of the base element are independent to one another. Preferably, the first, second, and third material are made of silicon oxide-based material or firebrick-based material. Even more preferably, any one of the first, second, and third material is made of a silicon oxide-based material or a firebrick-based material.

Beforehand to the start of a drainage (or draining) process, the body of the drainage device according to the invention is mounted on the molten glass container (for instance a furnace) according to an installation process including the steps of: i) providing the anchoring element according to the invention; connecting the anchoring element to a borehole present on a base of a furnace, for instance by inserting the duct in the borehole, so that the anchoring element is irreversibly fluidically connected to an inside region of the furnace arranged to contain the molten glass fluid;

providing the containing element according to the invention;

connecting in a removable way the containing element to the anchoring element, for instance with a first screw-nut system, so as to allow the internal cavity of the containing element to be fluidically connected to the inlet opening of the anchoring element;

providing the base element according to the present invention; and

connecting in a removable way the containing element to the base element, for instance with a second screw-nut system, so as to allow the internal cavity of the containing element to be fluidically connected to the outlet opening of the base element; and

connecting each of the first, second and third heating circuit to its respective (first, second and third) heating means.

During operation of the drainage device, implying that the furnace has been filled with a molten- glass-based fluid after installation of the drainage device, a fraction of contaminated molten glass-based fluid (i.e. a fraction of molten glass comprising impurities) flows through the inlet orifice 6 and the duct 7 toward the internal cavity of the containing element. Such a transfer of this fraction of molten glass is made possible by switching on the first heating means for heating the inner surface of the inlet orifice and the duct, so that an access for the molten glass-based fluid to the inside cavity of the containing element is created, by allowing the fraction of molten glass to remain in a liquid form when flowing out of the furnace via the borehole.

The fraction of molten glass flows through the internal cavity toward the base element and resides for a certain time in this internal cavity before to be expelled out of the body of the drainage device through the outlet orifice of the base element.

The passage of the fraction of molten glass-based fluid through the internal cavity and the outlet orifice is ensured by switching on the second and third heating means for heating the inner surfaces of the internal cavity and of the outlet orifice.

The drainage operation is stopped when the first heating means is switch off, so that the inlet orifice inner surface and the duct are cooled to an ambient temperature and the access of the molten glass-based fluid to the internal cavity of the containing element is prevented. The present invention also concerns a process of repairing/restoring the draining device according to the present invention, the drainage device being fluidically connected to the molten glass container (which can be a furnace), each of the heating circuits being connected to its respective heating means.

The process comprises the following steps: a) switching off the first heating means, so as to make a fraction of molten- glass-based fluid present in the duct to cool down and to solidify, preventing access of the molten glass-fluid to the containing element of the body of the drainage device;

b) optionally keeping the second heating means switched on so as to allow a remaining fraction of the molten glass-based fluid present in the internal cavity to be evacuated (via flowing) in direction to the base element;

c) optionally keeping the third heating means switched on so as to allow the remaining fraction of molten glass-based fluid to be expelled out of the body of the drainage device;

d) switching off the second and third heating means so as to cool down the containing and the base element to an ambient temperature. Also, switching off the second means can be done before or after switching off the third means;

e) eventually disconnecting the base element from the containing element;

f) eventually disconnecting the containing element from the anchoring element;

g) eventually transporting the base element and/or the containing element for

restoring/reparation in a handling area;

h) restoring and/or replacing the containing element and/or the base element of the body; i) connecting in a removable way a restored/repaired containing element and/or a

restored/repaired base element to the anchoring element, so that the anchoring element, the containing element and the base element are again removably connected to one another; and/or

j) connecting in a removable way a new (replaced) containing element according to the invention and/or a new (replaced) base element according to the invention to the anchoring element, so that the anchoring element, the containing element and the base element are again removably connected to one another; and

k) implementing a new loop (restarting) of (the) draining (process) by operating again the drainage device.

Optionally, the steps a) and d) can be realized simultaneously. Preferably, the drain comprises a water cooling system so that steps a) and d) can be further implemented by cooling the anchoring, containing, and base elements via said water cooling system.

When (re)starting the drainage device, the operator does:

A) In a first step, switch on the third heating means, inducing through the third heating

circuit a local heating of the inner surface of the outlet orifice and an eventual melting of cooled glass present in and obstructing said outlet orifice, if present. The inner surface of the outlet orifice is heated and maintained during the drainage operation to a first predetermined temperature T1 , T1 being sufficient so as to allow a fraction of molten glass-based fluid to flow through said outlet orifice so as to be expelled out of the drainage device body.

B) In a second step, the second heating means is switched on so as to heat the inner

surface of the internal space of the body contained in the containing element at a second predetermined temperature T2, allowing an eventual melting of cooled glass present in the internal space of the body, said second predetermined temperature T2 being sufficient for allowing a fraction of molten glass-based fluid to flow from the first inlet orifice to the outlet orifice. Said second predetermined temperature T2 is

maintained at a sufficient value for allowing a fraction of molten glass-based fluid to flow from the first inlet orifice to the outlet orifice during the drainage operation.

C) In a third step, the inner surface of the inlet orifice is heated by (via the first heating

circuit connected to) the first heating means to a third predetermined temperature T3 that is sufficient for allowing an eventual melting of cooled glass present in and obstructing said inlet orifice. Said third predetermined temperature T3 is maintained at a sufficient value for allowing a fraction of molten glass-based fluid to flow from the borehole to the internal space of the containing element through said outlet orifice during the drainage operation.

An operator can therefore design and control/monitor a predetermined temperature profile (from the contribution of T1 + T2 + T3) so as to define an appropriate gradient of temperature during operation of the drainage device. Please note that steps A), B) and C) can be performed in any successive order.

Alternatively, the first, second and third heating means can be switched on simultaneously. It is understood that the present invention is by no means limited to the forms of the above drainage device embodiments and that many modifications can be made without departing from the scope of the appended claims. For instance, it must be understood that if the description discloses that each heating circuit HC1 , HC2 and HC3 is connected to a corresponding heating means, the scope of the invention also covers an embodiment wherein the heating circuit are connected to a single heating means suitable for modulating independently a heating input to each of the heating circuits. Also, it must be understood that, for (re)starting a draining device according to the present invention; provided that the draining device is connected to the furnace [when the above- mentioned steps i) - vii) or steps h) to k) are accomplished]; the operator can (re)start the draining process by heating, via the respective heating circuits, the different elements in an optimal order, not necessarily by heating: i) first the inlet orifice and eventually the duct; ii) secondly the inner surface of the internal space of the containing element; iii) thirdly the outlet orifice and eventually the nozzle; but the operator can also first heat the outlet orifice (and eventually the nozzle) before heating the inner surface of the internal cavity of the containing element. The present invention also concerns a second drainage device (see for instance, but not limited to, figure 3) for draining molten glass-based fluid from a borehole 13 provided in a base 1 1 of a container containing said molten glass-based fluid. This second draining device is a variant of the (first) draining device according to the present invention described above. The second drainage device comprising a body 1 having an inlet orifice 6, to be fluidically connected to the borehole 13, for allowing a fraction of the molten glass-based fluid comprising undesired substances to flow from the container to an outlet orifice 9 of the body, fluidically connected to the inlet orifice of the body, for evacuating therethrough said fraction of molten-glass comprising the impurities from the container, an inner surface of the outlet orifice 9 being suitable for contacting with the molten glass-based fluid, said draining device being characterized in that said body comprises:

an anchoring element 3 made of a first material and to be connected to an outer surface of the base of the container, said anchoring element comprising the inlet orifice 6 and a first heating circuit HC1 ' to be connected to a first heating means for heating an inner surface 14 of the inlet orifice 6 suitable for contacting with the fraction of the molten glass-based fluid; and a base element 5 made of a second material and comprising said outlet orifice 9 having its inner surface connected to a second heating circuit HC2' to be connected to a second heating means for heating said inner surface of said outlet orifice,

said anchoring element 3 and base element 5 being removably connected to one another, said first and second heating circuits being independent from one another, so that said first and second heating circuits are arranged to be heated by the corresponding heating means independently from one another.

Other details and advantages of the present invention will become apparent from the

description hereunder of preferred and non-limitative embodiments of the second drainage device according to the invention:

Embodiment 1

In a first embodiment of the second drainage device according to the invention, the first heating circuit HC1 ' is directly and/or indirectly connected to the inner surface 14 of the inlet orifice 6 of the anchoring element 3.

Embodiment 2

In a second embodiment of the second drainage device according to the invention, the anchoring element 3 comprises a duct 7 fluidically connected to the inlet orifice 6, said duct being arranged to be (preferably irreversibly) inserted in an inner space of the borehole of the container (furnace) so as to be anchored to the container (furnace).

In a specific embodiment of the Embodiment 2, the duct is made of at least one metal selected from the PMG group. Embodiment 3

In a third embodiment of the second drainage device according to the invention, the first heating circuit is indirectly connected to the duct and the inner surface of the first orifice.

Optionally, the first heating circuit is indirectly connected to the duct or to the inner surface of the first orifice. In this Embodiment 3, said duct and first heating circuit are preferably at least partially encased into said anchoring element.

Optionally, said duct or said inner surface of the inlet orifice are separated from at least a part of the first heating circuit by the first material of said anchoring element, so that the first heating circuit is arranged to indirectly heat the duct or the inner surface of the inlet orifice.

Embodiment 4

In a fourth embodiment of the second drainage device according to the invention, the first material comprises ceramic.

Embodiment 5

In a fifth embodiment of the second drainage device according to the invention, the first heating circuit is made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the first heating circuit.

Also, the second heating circuit can be made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the second heating circuit.

Embodiment 6

In a sixth embodiment of the second drainage device according to the invention, the first heating circuit is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the first heating circuit into heat.

Also, the second heating circuit can be made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the second heating circuit into heat. Embodiment 7

In a seventh embodiment of the second drainage device according to the invention, the first heating circuit is made of at least one metal of the PMG of metals. Embodiment 8

In an eighth embodiment of the second drainage device according to the invention, the inner surface of the inlet opening is covered, at least partially, by a covering material comprising at least one metal chosen from the PMG group of metals. Optionally, the inner surface of the inlet opening is covered, at least partially, by a first covering material comprising at least one metal chosen from the PMG group of metals, said first covering material being directly and/or indirectly connected to the first heating circuit.

Embodiment 9

In a 9^th embodiment of the second drainage device according to the invention, the outlet orifice is fluidically connected to a nozzle. When the base and the anchoring elements are (removably) connected, the nozzle is preferably (at least partially) encased in an open cavity that is present in the anchoring element. Optionally, when the anchoring element is removably connected to the base element, the nozzle is encased in the open cavity of the anchoring element and fluidically connected to the inlet orifice. Moreover, the nozzle is preferably surrounded by the second material of the base element and therefore at least partially encased in the base element.

Embodiment 10

In a 10^th embodiment of the second drainage device according to the invention, the first heating circuit HC1 ' is encased in the first material of the anchoring element and indirectly connected to the inner surface of the inlet orifice, preferably of the inlet orifice and/or of the duct, said first material being a heat conductor material. In an optional embodiment of Embodiment 10, the second heating circuit is directly connected to the outlet orifice (and optionally the nozzle) and encased at least partially in the second material constituting said base element. The second material is preferably made of a heat insulator material. When the base element and the anchoring elements are assembled together, the presence of a heat conductor material in the first material of the anchoring element allows indirect heating of the outlet orifice and optionally of the nozzle. Embodiment 11

In a 1 1 ^th embodiment, the second drain according to the invention optionally comprises a containing element 4 made of a third material, said containing element being destined to be placed between and removably connected to said anchoring element 3 and said base element 5, said containing element having an internal space 8 arranged to be fluidically connected to the inlet and outlet orifices.

Embodiment 12

In a 12^th embodiment which is an alternative to the 1 1 ^th embodiment, the second drain according to the invention optionally comprises a containing element 4 made of a third material, said containing element extending from the anchoring element so that the anchoring element and the containing element constitute a single piece (i.e. a single entity). The containing element has internal space fluidically connected to the inlet orifice. The containing element is destined to be removably connected to said base element 5, the internal space 8 is further arranged to be fluidically connected the outlet orifice of the base element.

Embodiment 13

In a 13^th embodiment, the second drain according to the invention comprises a third heating circuit HC3' to be connected to a third heating means for heating an inner surface 16 of the internal space 8 suitable for contacting the fraction of the molten glass-based fluid, said third heating circuit being independent to the first and second heating circuits HC1 '; HC2', so that said first, second, and third heating circuits are arranged to be heated by the corresponding heating means independently from one another. Optionally, said containing element comprises said third heating circuit.

Preferably, said third heating circuit is directly and/or indirectly connected to the inner surface of the internal space of the containing element. Embodiment 14

In a 14^th embodiment of the second drain, the inner surface of the internal space is corrugated and formed by a series of valleys and ridges.

Embodiment 15

In a 15^th embodiment of the second drain according to the invention, the containing element comprises a (preferably cylindrical) conduit made of at least one metal selected from the group of platinum metals (so-called PMG [Platinum-Metal-Group] group), said conduit being arranged to be fluidically connected to the inlet and outlet orifices, said internal space of the containing element being defined by an inner space of the conduit and said inner surface of the containing element being defined by an inner surface of the conduit. In particular, the hollow conduit is a hollow tube (of the containing element) or a cylindrical- shaped conduit.

In a preferable embodiment of the Embodiment 15 of the second drain, said valleys and said ridges are parallel to one other and arranged so that a valley is intercalated between two ridges.

Embodiment 16

In a 16^th embodiment of second drain according to the invention, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to a duct and an inner surface of the inlet orifice of the anchoring element, the duct and the inner surface of the inlet orifice being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element.

Alternatively, when said anchoring element is removably connected to said containing element, the second heating circuit is arranged so as to be indirectly connected to a duct or an inner surface of the inlet orifice of the anchoring element, the duct or the inner surface of the inlet orifice of the anchoring element being preferably separated from at least a part of the second heating circuit by the first material of the anchoring element.

Embodiment 17

In a 17^th embodiment of the containing element according to the invention, when said base element is removably connected to said containing element, the third heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice of the base element and to a nozzle of the base element, the inner surface of the outlet orifice and the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element and said containing element. Alternatively, when said base element is removably connected to said containing element, the third heating circuit is arranged so as to be indirectly connected to the inner surface of the outlet orifice or to a nozzle of the base element, the inner surface of the outlet orifice or to the nozzle being preferably separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element or said containing element.

Embodiment 18

In an 18^th embodiment of the second draining device according to the present invention, the third material comprises ceramic, mullite, firebricks, or silicon oxides.

Embodiment 19

In a 19^th embodiment of the second drain according to the present invention, the third heating circuit is made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the third heating circuit.

Embodiment 20

In a 20^th embodiment of the containing element according to the present invention, the third heating circuit is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the third heating circuit into heat.

Embodiment 21

In a 21 ^st embodiment of the containing element according to the invention, the second heating circuit is made of at least one metal of the PMG of metals.

Embodiment 22

In a 22^nd embodiment of the containing element according to the invention, the inner surface of the internal space is covered, at least partially, by a covering material comprising at least one metal chosen from the PMG group of metals.

Optionally, the inner surface of the internal space is covered, at least partially, by a second covering material comprising at least one metal chosen from the PMG group of metals, said second covering material being directly and/or indirectly connected to the second heating circuit. Each of the individual second drainage device Embodiments 1 to 22 described hereabove may be combined with one or more of the second draining device embodiments described before it.

The present invention also concerns a third drainage device for draining molten glass-based fluid from a borehole provided in a base of a container suitable for containing said molten glass- based fluid, said drainage device comprising a body having an inlet orifice to be fluidically connected to the borehole, for allowing a fraction of the molten glass-based fluid comprising undesired substances to flow from the container to an internal space of the body arranged to receive said fraction of the molten glass-based fluid comprising undesired substances, the body comprising an outlet orifice, fluidically connected to the internal space of the body, for evacuating therethrough said fraction of molten-glass comprising the impurities from the internal space of the body, said draining device being characterized in that said body comprises a duct fluidically connected to the inlet orifice, said duct being arranged to be (preferably irreversibly) inserted in an inner space of the borehole of the furnace so as to be anchored to the furnace, said drainage device comprising a first heating circuit to be connected to a first heating means for heating an inner surface of the duct.

description hereunder of preferred and non-limitative embodiments of the third drainage device according to the invention:

Embodiment 1

Optionally, in the third drainage device according to the invention, said duct is directly and/or indirectly connected to the first heating circuit and is therefore arranged to be (preferably directly and/or indirectly) heated by said first heating circuit.

In a specific embodiment of the Embodiment 1 of the third draining device according to the present invention, the duct is made of at least one metal selected from the PMG group. Embodiment 2

In a 2^nd embodiment of the third drainage device according to the invention, the first heating circuit is indirectly connected to the duct and the inner surface of the first orifice.

Optionally, the first heating circuit is indirectly connected to the duct or to the inner surface of the first orifice. In this Embodiment 2 of the third drainage device according to the invention, said duct and first heating circuit are preferably at least partially encased into said anchoring element.

The advantage of an indirect heated anchoring element (which is inserted in the borehole of the furnace) is that the inner surface can still be heated even if it is cracked. Those cracks can be mechanical cracks caused by different or hindered thermal expansions of the PGM. Cracks or material damages can also occur due to a chemical attack of aggressive glass components to the PGM.

Therefore an indirectly heated anchoring element is a preferred execution which allows longer lifetime.

Embodiment 3

In a 3^rd embodiment of the of the third drainage device according to the invention, the first material comprises ceramic. Embodiment 4

In a 4^th embodiment of the of the third drainage device according to the invention, the first heating circuit is made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the first heating circuit.

Embodiment 5

In a 5^th embodiment of the third drainage device according to the invention, the first heating circuit is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the first heating circuit into heat. Embodiment 6

In a sixth embodiment of the third drainage device according to the invention, the first heating circuit is made of at least one metal of the PMG of metals. Embodiment 7

In a 7^th embodiment of the third drainage device according to the invention, the inner surface of the inlet opening is covered, at least partially, by a covering material comprising at least one metal chosen from the PMG group of metals. Optionally, the inner surface of the inlet opening is covered, at least partially, by a first covering material comprising at least one metal chosen from the PMG group of metals, said first covering material being directly and/or indirectly connected to the first heating circuit.

Preferably, the duct comprises at least one metal chosen from the PMG group of metals.

Each of the individual third drainage device Embodiments 1 to 7 described hereabove may be combined with one or more of the third draining device embodiments described before it.

The present invention also concerns a fourth drainage device for draining molten glass-based fluid from a borehole provided in a base of a container suitable for containing said molten glass- based fluid, said drainage device comprising a body having an inlet orifice to be fluidically connected to the borehole, for allowing a fraction of the molten glass-based fluid comprising undesired substances to flow from the container to an internal space of the body arranged to receive said fraction of the molten glass-based fluid comprising undesired substances, the body comprising an outlet orifice, fluidically connected to the internal space of the body, for evacuating therethrough said fraction of molten-glass comprising the impurities from the internal space of the body, said draining device being characterized in that said body comprises a nozzle fluidically connected to said outlet orifice and encased in the body of the draining device, said nozzle being arranged to be crossed by the molten glass-based fluid, said nozzle being connected to a first heating circuit, so that the first heating circuit is arranged to heat the nozzle when said heating circuit is connected to a heat source.

Encasement of the nozzle in the body allows to reduce the heat loss at the outlet region of the drain and to the ambient. Other details and advantages of the present invention will become apparent from the

description hereunder of preferred and non-limitative embodiments of the fourth drainage device according to the invention: Embodiment 1

In a 1^st embodiment of the fourth draining device according to the invention, the first heating circuit is made, at least partially, of a thermally conductive material and is arranged to be connected to a heat generator destined to generate heat to be distributed by the first heating circuit.

Embodiment 2

In a second embodiment of the fourth draining device according to the invention, the first heating circuit is made, at least partially, of an electrically resistant material for converting an electric current into heat, and is arranged to be connected to an electric current generator destined to generate an electric current to be converted by the first heating circuit into heat.

Embodiment 3

In a 3^rd embodiment of the fourth draining device according to the invention, the first heating circuit is made of at least one metal of the PMG of metals.

Embodiment 4

More preferably, in a fourth embodiment of the fourth draining device according to the invention, the inner surface of the outlet orifice is covered by a covering material comprising at least one metal chosen from the PMG group of metals, said second covering material being directly and/or indirectly connected to the first heating circuit.

Each of the individual 4^th drainage device Embodiments 1 to 4 described hereabove may be combined with one or more of the fourth draining device embodiments described before it. Although the different embodiments of the inventions described above may relate to a specific application of the draining device and its elements in combination with a furnace, it must be understood that these embodiments relate to a draining device (and its elements) which are suitable for draining glass from a molten-glass container, including for instance (but not limited to it) a borehole of a refining furnace, a float bath container, etc.

Claims

1 . - A drainage device (2) for draining molten glass-based fluid from a borehole (13) provided in a base (1 1 ) of a container suitable for containing said molten glass-based fluid, said drainage device comprising a body (1 ) having an inlet orifice (6) to be fluidically connected to the borehole (13), for allowing a fraction of the molten glass-based fluid comprising undesired substances to flow from the container to an internal space (8) of the body arranged to receive said fraction of the molten glass-based fluid comprising undesired substances, the body comprising an outlet orifice (9), fluidically connected to the internal space (8) of the body, for evacuating therethrough said fraction of molten-glass comprising the impurities from the internal space (8) of the body, said draining device being characterized in that said body comprises: an anchoring element (3) made of a first material to be connected to the base of the container, said anchoring element comprising the inlet orifice (6) and a first heating circuit (HC1 ) to be connected to a first heating means for heating an inner surface (14) of the inlet orifice (6);

a base element (5) made of a second material; and optionally

a containing element (4) made of a third material and comprising said internal space (8) and a second heating circuit (HC2) to be connected to a second heating means for heating an inner surface (16) of the internal space (8), said containing element (4) being placed between said anchoring element (3) and said base element (5),

said base element comprising the outlet orifice (9) having its inner surface that is connected to a third heating circuit (HC3) to be connected to a third heating means for heating said inner surface of said outlet orifice, said anchoring element (3), base element (5), and the optional containing element (4) being removably connected to one another, said first, the optional second; and the third heating circuits being independent from one another, so that said first, the optional second; and the third heating circuits are arranged to be heated by the corresponding heating means independently from one another.

2. - The drainage device according to claim 1 , characterized in that it comprises a duct (7) fluidically connected to the inlet orifice (6), said duct being arranged to be inserted in an inner space of the borehole of the container so as to be anchored to the container and to be crossed by the molten glass-based fluid.

3. - The drainage device according to claim 2, characterized in that the duct (7) is connected to the first heating circuit (HC1 ) and is arranged to be heated by said first heating circuit.

4.- The drainage device according to any of claim 1 to 3, characterized in that the base element (5) comprises a nozzle (21 ) fluidically connected to said outlet orifice (9) of the base element, said nozzle being arranged to be crossed by the molten glass-based fluid.

5.- The drainage device according to claim 4, characterized in that the nozzle (21 ) is directly connected to the third heating circuit (HC3), so that the third heating circuit is arranged to directly or indirectly heat the nozzle.

6. - The drainage device according to any of claim 1 to 5, characterized in that the first heating circuit (HC1 ) is indirectly connected to the duct (7) and/or the inner surface (14) of the first orifice (6), said duct and first heating circuit being preferably at least partially encased into said anchoring element (1 ), and said duct and/or inner surface of the inlet orifice being separated from at least a part of the first heating circuit by the first material of said anchoring element, so that the first heating circuit is arranged to indirectly heat the duct and/or the inner surface of the inlet orifice.

7. - The drainage device according to any of claim 1 to 6, characterized in that the second heating circuit (HC2) is directly connected to the inner surface (16) of the internal space (8) of the containing element (4).

8. - The drainage device according to any of claim 1 to 7, characterized in that, when said base element (5) is removably connected to said containing element (4), the second heating circuit (HC2) of the containing element (4) is arranged so as to be indirectly connected to the inner surface (20) of the outlet orifice (9) and/or to the nozzle (21 ), the inner surface of the outlet orifice and/or to the nozzle being separated from at least a part of the second heating circuit by the second material of the base element or by an intermediate space formed between said base element and said containing element.

9. - The drainage device according to any of claim 1 to 8, characterized in that the first, second, and third heating circuits are made, at least partially, of a thermally conductive material and are arranged to be connected to a heat generator destined to generate heat to be distributed by the heating circuits.

10.- The drainage device according to any of claim 1 to 9, characterized in that the first, second, and third heating circuits are made, at least partially, of an electrically resistant material for converting an electric current into heat, and are arranged to be connected to an electric current generator destined to generate an electric current to be converted by the heating circuits into heat.

1 1 .- The drainage device according to any of claim 9 or 10, characterized in that the first, second, and third heating circuits are made of at least one metal of the Platinum-Metal-Group (PMG) of metals.