DE102005054319B4 - Modular skull crucible, boundary and extension elements and method for melting and / or refining an inorganic substance, in particular of glass - Google Patents

Abstract

Skull crucible (1), in particular for melting and / or refining glass, which has at least one coolable side wall (2) and at least one bottom plate (3), wherein the side wall (2) has at least a first and a second basic limiting element (20, 200) comprising a plate (24, 240, 241) made of solid material, which has a substantially flat melt contact surface (25), a bottom surface (26) for mounting the basic limiting element (20, 200) on the bottom plate (3), an outer surface ( 27) and a first and a second connection surface (208, 209), wherein at least the first connection surface (208) of the first basic limiting element (20, 200) is complementary to at least one connection surface (209) of the second basic limiting element (20, 200) to the first basic limiting element (20, 200) to the second basic limiting element (20, 200) for building at least a part of the side wall (2) of the Skulltiegels (1), in particular under Ausb Forming a positive connection to connect, wherein the plate (24, 240, 241) at least one channel arranged in its interior ...

Description

The invention relates to a skull crucible, in particular for melting and / or refining glass, boundary and extension elements and a method for melting and / or refining using the skull crucible.

Many different materials undergo the aggregate state of the melt during their production or processing. This applies to elements as well as to alloys, compounds or mixtures. In this case, various types of melting plants are used, depending on the properties and requirements with respect to the products to be manufactured, the materials of the melting vessel, its construction and size and the nature of the heating of the melt are selected. The melting unit and the melting process should be designed so that the highest possible product quality is achieved at the lowest possible cost of manufacture and operation of the melting vessel for melting the material in question.

Usually melting vessels are designed so that they withstand even the temperatures occurring during melting of the materials in question and are attacked as little as possible from the melt at these temperatures. Since an interaction of the melted material with the material of the melting vessel can usually not be completely ruled out, a further requirement for the melting vessel is that the melt contact material, that is the material which is in contact with the melt during operation of the melting plant, neutral the required properties of the melt material affects when it is registered by the attack of the melt in this.

For the melting of metals therefore usually oxide ceramics are used, which are wetted by the metals only very little and leave in an attack of the melt as slag again. For oxidation-endangered metals and alloys, carbonaceous vessels are also used. Enamel, ceramics, crystals and glasses can also be melted in ceramic vessels. Since such materials are chemically very similar to the ceramic material of the melting vessel, melting vessels for the smelting of enamel, ceramics, crystals and glasses are endangered by a more or less strong attack of the chemically very similar melt.

Such an attack can lead to a lack of durability or service life of the melting vessels and at the same time to a high entry of the melt contact material used in the melt. This corrosion effect is also strongly temperature-dependent. In the often desired or necessary high melting temperatures, the attack of the melt on the vessel wall increases extremely. At temperatures above 1800 ° C, the refractory materials used in conventional melting units without further measures no longer able to reliably withstand attack for a long time.

For example, for smelting of chalcogenide, oxide, fluoridic and similar systems can also metallic, at higher melting temperatures and / or higher purity requirements of the melt and noble metal melting vessels are used. In this case, platinum and its alloys, preferably platinum / rhodium or platinum / iridium but also platinum / gold or iridium and its alloys can be used. Such melting vessels can be used in many glasses up to high temperatures.

Even if platinum and its alloys are used under oxidizing conditions and iridium under inert or slightly reducing conditions, it is also possible for these melt vessels to attack and thus introduce the melt contact materials into the melt. Even with an entry with a noble metal content in the ppm range, at least a slight coloration of the product is associated with it, wherein in addition also other properties, such as the crystallization behavior or the electrical conductivity of the glass can be influenced.

In order to realize high temperatures in the melt and yet almost no attack on the melt contact material of the melting vessel, so-called cold wall or Skulltiegel be used. Such skull crucibles are for example in the documents DE 101 33 469 A1 . DE 199 39 772 C1 and DE 102 44 807 A1 the applicant described. The cooling effect of the coolant, which may be water, for example, is so high in skull crucibles that solidifies the melt at the melt contact surfaces of the crucible and thus the melt itself becomes the contact material for the melt. The melt is then, so to speak, melted in the species-specific material, so that contamination of the melt by the material of the melting vessel is excluded.

The EP 0 538 024 A1 describes an inductively heated crucible consisting of segments and whose walls are cooled by water. The number of segments of a crucible can be changed by varying the dimensioning of the segments.

The EP 0 345 541 A2 shows a method for producing a cold crucible. The crucible consists of wall segments and a base part. Cooling channels run in the wall segments. The discharge pipes of the cooling system function as a connecting part between the upper part and the Baisteil of the crucible.

Also the EP 0 398 821 A2 shows a segmented induction crucible. Between the segments forming the sidewalls are slots which are free of packing material to prevent contamination of the melt.

Finally, the shows US Pat. No. 6,817,212 B1 the Applicant a skull crucible for melting glass or glass ceramic. The crucible is heated inductively. The side wall of the crucible consists of metal pipes that can be connected to a coolant supply.

Skull crucibles are usually made using tubes that can be flowed through by coolant. Because of the high thermal conductivity and good processability such tubes are often made of copper. For skull crucibles, however, the use of brass, steels or non-magnetic stainless steels and precious metals comes into question. Likewise, aluminum or its alloys can be used.

Because glasses do not have a defined melting point and practically never solidify completely, the melting and melting of glasses in such skull crucibles inevitably leads to constant buildup and dismantling of the skull layer due to diffusion and convection effects even at low temperatures near the wall Entry of the material of the melting vessel into the melt. Known melting vessels therefore have the disadvantage of contaminating the melts with constituents of the melting vessel material.

The entry of aluminum ions in the melt compared to the other materials mentioned has the advantage that aluminum ions usually do not discolor glass melts. In contrast to the coloring heavy metal ions, aluminum is tolerated in many raw materials anyway as a trace impurity in the production of glass melts. However, a disadvantage with regard to the use of aluminum as a material for a skull crucible is the low mechanical stability of skull crucibles made of aluminum tubes. The processability and above all the availability of pipes and individual parts made of aluminum therefore make these skull crucibles very expensive and expensive. The low hardness at the high temperatures to which the material of Skulltiegels is exposed, the long-term stability against the abrasive glass melts and the mixture also disadvantageously greatly reduced.

Furthermore, during the operation of known skull crucibles, intensive investigations by the inventors on the walls of the crucible have shown that straight tubes are particularly susceptible to corrosion. One reason for this is that, because of their manufacture, the tubes comprise materials that have already undergone a machining history. As a result, the material processed into tubes no longer offers the same strength and hardness characteristics as they actually are a property of the material being processed. In addition, it has been found that the tubes with round cross section, which are mostly used, are more susceptible to corrosion than tubes with an angular cross section.

In order to avoid corrosion of the cooling tubes and thus contamination of the glass melt largely is in the document WO 01/53222 A1 the applicant proposed the use of plastic layers, which act as a diffusion barrier. With such plastic layers, a protective effect for the cooling tubes can be achieved. However, it has been shown that this protective effect can not be maintained over long periods of time. The plastics have a low thermal conductivity and are at the same time poorly wetted by glass melts.

Depending on the treated glass, the combination of both effects can lead to a poorly shaped skull crust and a low adhesion of the skull crust to the plastic-coated cooling tube surfaces. On the one hand, this results in a very high heat removal from the melt compared to uncoated surfaces of the cooling tubes, on the other hand, there is a build-up of heat on the plastic layer, which leads to a strong overheating of the plastic layers and finally to their destruction. The plastic layers are also not very resistant to abrasive substances, such as the discontinued mixture. Especially in the area of the so-called scavenging edge, that is, the three-phase interface between the melt surface, the melting vessel wall and the melting atmosphere, the abrasive material to be melted rapidly destroys the plastic layer and lifts its protective effect.

If contamination of the glass melt by aluminum ions can be tolerated, such diffusion barrier coatings could be dispensed with on the aluminum tubes of a skull crucible. However, the tubes themselves have one Low hardness, especially at the high temperatures to which the material is exposed, that the long-term stability against the abrasive melts and the mixture is not given.

It thus results in an object of the invention to provide a skull crucible, in particular for melting and / or refining of glass available, which has a high mechanical strength even over long periods of time away, and in which a contamination of the melt, which treated in the crucible is largely avoided by due to corrosion in the melt registered components of the crucible wall. The crucible should also be structurally simple.

Another object of the invention is to provide a way to flexibly adapt the crucible to different requirements of the melting process, in particular as regards the throughput of material to be melted, the average residence time of the melt in the crucible and thus the required size of the crucible.

In addition, it is an object of the invention to provide a Skulltiegel, in which a stable, thickest possible skull crust can form on the metallic melt contact surface.

These objects are achieved in a surprisingly simple manner with a skull crucible and with a method for melting and / or refining an inorganic substance, in particular glass, using such a skull crucible according to the independent claims. Advantageous developments are the subject of the respective associated subclaims.

The invention provides a skull crucible, in particular for melting and / or refining glass, which has at least one coolable side wall and at least one bottom plate, wherein the side wall comprises at least a first and a second basic boundary element comprising a plate made of solid material, which has a substantially flat fused contact surface, a bottom surface for mounting the basic limiting element on the bottom plate, an outer surface and a first and a second terminal surface comprises, wherein at least the first connection surface of the first basic limiting element is complementary to at least one connection surface of the second basic limiting element, to the first basic limiting element the second basic limiting element for building at least a part of the side wall of Skulltiegels, in particular to form a positive connection to connect, and wherein the plate at least one in its interior a has subordinate channel, which can be traversed by a cooling medium. In particular, the elements can be designed so that further boundary elements can be connected with identically designed connection surfaces.

By providing a plate of solid material as a basic limiting element, it is advantageously possible to dispense with the use of constructions made of tubes for a side wall of a skull crucible. With the help of the invention, therefore, a Skulltiegel is created, which has a high mechanical strength even over long periods of time away. Since inside the plate at least one channel is arranged, which can be flowed through by a cooling medium, a high cooling capacity is provided at the same time with high strength. Thus, a stable scull crust forms during operation, and the entry of components of the crucible wall in the melt or the melt is largely reduced.

The basic limiting element is made in a preferred embodiment of the invention made of metal, in particular aluminum or an aluminum alloy. The basic limiting element may in particular consist of the plate made of solid material, which can be equipped with connections, for example for the coolant supply. Thus, the invention provides limiting elements for a skull crucible, which have a very simple external structure. By the connecting surfaces of basic boundary elements, as described above, are complementary to each other, can be provided on a modular principle quickly and easily Skulltiegel for the respective predetermined melting task, without measures must be taken in another manufacturing step to build the Skulltiegel measures to the crucible To seal against the melt.

In a preferred development, it is provided that the skull crucible comprises at least one further delimiting element for the modular construction of at least the side wall of the skull crucible, wherein the delimiting elements each have complementary shaped connecting surfaces. The pads can be shaped in the invention in a particularly simple manner, in particular identical.

The term "limiting element" in the following basic limiting elements, as described above, as well as extension limiting elements are discussed in more detail below. In the context of the invention, the boundary elements in different variants arranged and combined with each other.

According to the invention, the limiting elements can be connected to each other mechanically detachable. For this purpose, for example, at least one screw and / or at least one connector can be provided. Advantageously, the limiting elements are thus quickly detachable from each other or quickly connected to each other, so that a large variability for the design of Skulltiegels from the limiting elements is given at the same time fast assembly and disassembly of Skulltiegels.

Advantageously, the skull crucible may comprise at least a first extension-limiting element comprising a plate of solid material comprising a substantially flat melt contact surface, a bottom surface for mounting the first extension-limiting element on the bottom plate, an outer surface and a first and a second pad, wherein at least the first Connecting surface of the first extension limiting element complementary to at least one connection surface of a Grundbegrenzungselements is designed to connect the first extension limiting element to a Grundbegrenzungselement for building at least a portion of the side wall of Skulltiegels, in particular to form a positive connection, said plate having at least one channel disposed in its interior, which can be flowed through by a cooling medium. In the simplest case, in the context of the invention, the skull crucible can be constructed solely from basic boundary elements. This simplest construction can be increased by the use of a first extension limiting element. The extension limiting element also offers the advantages described above for the basic limiting element. The pads can be formed in the invention in particular identically.

In a further preferred embodiment, the skull crucible comprises at least one second extension-limiting element which comprises a plate made of solid material, which has a substantially flat melt contact surface, a bottom surface for placing the second extension-limiting element on the bottom plate, an outer surface, and a first and a second connection surface, wherein the first terminal surface of the second extension-limiting element is complementary to the second terminal surface of the first extension-limiting element, and wherein the second terminal surface of the second extension-limiting element is complementary to the first terminal surface of another second extension-limiting element, around the second extension-limiting element to a first and / or to another second extension-limiting element for building at least a part of the side wall of Skulltiegels, in particular under Form to join a positive connection, wherein the plate has at least one channel disposed in its interior, which can be traversed by a cooling medium. The use of a second extension-limiting element advantageously allows a further enlargement of the skull crucible, wherein in addition to a particular further second boundary elements can be used.

The invention as a whole is constructed so that when joining all n limiting elements, of which at least three are usually used, results in a self-contained side wall. It follows that the melt contact surfaces of the limiting elements have an angle γ of γ = 180 ° / n to the next side wall. That is, if the base is triangular, γ has an angle of 60 °, if the base is quadrangular, γ has an angle of 45 °, if the base is pentagonal, γ has an angle of 36 °, and so on.

In a development of the invention, it is provided that the second connection surface of the first extension limiting element, the first connection surface of the second extension limiting element and the second connection surface of the second extension limiting element enclose an angle of 90 ° with the melt contact surface of the respective limiting element. This allows a particularly simple construction of the skull crucible with straight side walls which comprise the extension limiting elements. The pads of the extension-limiting elements then abut one another at right angles to the melt-contacting surface of the side wall, which is formed by the extension-limiting elements.

For example, if the sidewall is subjected to a large pressure load from the melt inside the skull crucible, the restriction members can contribute to the stability of the sidewall when their lands are complementary and abut each other such that the compressive load on the abutment surfaces can be transmitted so that they do not solely by the connections of the boundary elements must be intercepted.

For this purpose, according to an advantageous development of the invention, it is provided that the melt contact surface of the first basic limiting element with the melt contact surface of the second Basic limiting element include an angle δ, which is δ = 360 ° / n. In this case, the total angle δ can be arbitrarily composed of the two individual angles. In particular, the invention provides that the second connection surface of the basic limiting element encloses an angle β ₁ with the melt-contacting surface of the basic limiting element, and the first connection surface of the first extension-limiting element encloses an angle β ₂ with the melt-contact surface of the first extension-limiting element, where β ₁ + β ₂ = 180 °.

Also, the second pad of the first extension-limiting element may include an angle β ₃ with the melt-contacting surface of the first extension-limiting element, and the first pad of the second extension-limiting element may include an angle β ₄ with the melt-contacting surface of the second extension-limiting element, β ₃ + β ₄ = 180 ° , The extension members may also contribute to the stability of the sidewall when their mating surfaces are complementary and abutting one another such that the compressive load on the abutment surfaces can be transferred so that it is not caught solely by the connections of the restrictor members.

For this purpose, according to an advantageous development of the invention, it is provided that the connection surface of the first basic limiting element with the connecting surface of the second basic limiting element enclose an angle ε which is ε = 180 °. In this case, the total angle ε can be arbitrarily composed of the two individual angles.

With this design of the connecting surfaces of the limiting elements, the mechanical strength against pressure load of the entire side wall can advantageously be increased and yet a straight, even melt contact surface of the side wall can be realized, in which essentially no dead zones for the melt are to be feared.

Depending on the available space, it may be useful to use a skull crucible with curved or polygonal side walls. Instead of an angle sum of 180 ° for the angles β ₁ + β ₂ or β ₃ + β ₄ , a correspondingly different, in particular smaller value than 180 ° can be selected in such a case.

In the invention, depending on which shape of the side walls is selected, the limiting elements comprise plates which, at least in the shape of the melt contact surface flat or - relative to a plane perpendicular to the bottom of Skulltiegels viewed - convex, concave, konvexkonkav or arbitrary, for example V-shaped, including at least one angle between the melt contact surface and the plane perpendicular to the bottom of Skulltiegels are formed. For example, the delimiting elements may be bent in such a way that the assembly of the delimiting elements results in a round, in particular a circular cross-section of the skull crucible.

In a preferred embodiment of the skull crucible according to the invention, the skull crucible has a cross section in the form of a polygon with a number N at corners, wherein the basic boundary elements are designed such that when connecting a basic boundary element to another basic boundary element a corner of the polygonal cross section of Skulltiegels is formed , With only one type of basic boundary elements can thus create a very simple, regularly shaped Skulltiegel. This skull crucible can in particular have an octagonal cross-section. Also skull crucibles with a square cross section are conceivable. By choosing the cross-sectional shape Skulltiegel invention can be easily adapted to different spatial conditions in which the melter must be inserted. In particular, the skull crucible can have an equilateral cross section.

According to the invention, the desired geometrical structure of the skull crucible can advantageously already be determined by the geometric configuration of the delimiting elements. A flexibility is given by the provision of basic and extension limiting elements. By virtue of the limiting elements according to the invention being in direct contact with each other via their connection surfaces, mispositioning or inaccurate alignment, which must be compensated for by the filling of gaps between the limiting elements, is advantageously precluded.

In addition, the invention has the advantage that the adjusting cross-section of the skull crucible is very precisely predetermined by the geometric design of the limiting elements, so that the basis in the design for the operation of the skull crucible metric conditions, which are important to the predetermined average residence times be able to comply with a defined throughput, in the practical implementation compared to the interpretation can be met very accurately.

The basic boundary elements can be used to form a cross-sectional shape of a skull crucible in the form of a polygon with a number N At corners especially easy to be designed so that at least one connection surface of a basic boundary element with the melt contact surface an angle α with α = (1 + 2 / N) · 90 ° includes.

In a preferred embodiment of the invention it is provided that the limiting element has a height H _W and is in contact with the melt crucible with its melt contact surface up to a height H _S measured from the bottom of the limiting element with a melt, which is located in Skulltiegel , wherein H _{S is} smaller than H _W , and that the limiting element at least in its melt contact surface in the range up to H _S measured from the bottoms of the delimiting element free of joints, in particular free of welded joints and / or solder joints and / or adhesive joints and / or frictional connections and / or positive connection and / or screw is.

This inventive design of the delimiting element advantageously reduces the risk of contamination of the melt by the material of the delimiting element and thus of the skull crucible in comparison to skull crucibles, which comprise walls with tubes and thus have the problem described above. In the skull crucible according to the invention, the melt advantageously does not substantially come into contact with material of the limiting element due to the design of the limiting element, which as a result of its processing during joining is susceptible to corrosive attack of the melt.

The limiting element may in particular have a height H _W which has a value in the range of greater than or equal to 10 cm to less than or equal to 1.5 meters, in particular in the range of greater than or equal to 30 cm to less than or equal to 1 meter.

The skull crucible according to the invention can be advantageously adapted to a wide variety of requirements for the operation of the melting. For example, the volume ingestible by the melt in the skull crucible, which is the product of height H _s and the area enclosed by the sidewall, may have a value in the range of greater than or equal to 0.005 m ³ to less than or equal to 0.3 m ³ .

In the context of the invention, the delimiting element may comprise a metal or a metal alloy, in particular platinum, a platinum alloy, aluminum or preferably an aluminum alloy. The inventive design of the limiting element can then be produced particularly easily by casting and / or with the aid of machining methods, in particular by milling.

In the simplest case, the plate may comprise at least one blind hole as a channel arranged in its interior, through which a cooling medium can flow. It is also within the scope of the invention that the plate has in its interior at least one U-shaped channel, which can be flowed through by a cooling medium has. Furthermore, the channel can also be designed by bores, for example by two blind holes whose lower ends are connected to one another. The channel may also be V-shaped by placing two blind holes at an angle in the plate so that their ends lying inside the plate fall together.

In order to ensure the coolant supply to the walls during operation of the skull crucible, the limiting element may comprise at least one coolant supply device and at least one coolant discharge device, which are arranged in particular on the same side of the limiting element. For example, the coolant supply device and the coolant discharge device can be arranged on the outer surface of the delimiting element.

The skull crucible according to the invention furthermore advantageously comprises at least one heating device for heating the melt in the interior of the skull crucible during operation. The heater may include fossil burners.

In a preferred embodiment of the invention it is provided that the heating device comprises a device for electrically heating the melt. This device can be designed in particular for an electrical resistance heating. For example, the heater may comprise electrodes. Furthermore, the heating device may comprise a device for inductive coupling of at least one electromagnetic field into the melt. In this case, it is envisaged that the skull crucible is designed so that it does not form an impenetrable Faraday cage for electromagnetic fields.

For this purpose, it is provided according to the invention that the plate of the limiting element and / or the bottom plate comprises at least one slot, so that the plate and / or the bottom plate can be penetrated by an electromagnetic field. The limiting element may in particular have a plurality of slots which are arranged between the cooling channels. In a preferred embodiment, the channels extend from an upper portion of the limiting element into the interior of its plate, wherein arranged between the channels slots are introduced from a lower portion of the limiting element.

In order to be able to efficiently use the heat introduced into the melt by means of the heating device for melting and at the same time to form a defined and stable skull crust, the inventors have found that this can be achieved in particular in a region near the melt contact surface of the side wall and / or the bottom plate of the skull crucible of the heat extraction is as large as possible. It has in fact been found that the skull layer forming in the contact and transition zone from the wall to the melt during operation of the skull crucible can reflect heat radiation from the heated melt.

When crystals or crystalline materials are melted, a polycrystalline skull crust with a high heat reflectivity forms when the temperature at the melt contact surface is kept below the melting temperature. However, when glassy or semi-crystalline materials are melted, there is no defined melting point below which the materials solidify in crystalline form. In this case, it is important to achieve a large temperature difference between the melt and the side wall by the highest possible heat removal at the melt contact surface in order to bring the particular remaining glass phase as much as possible to solidify.

In the material layer facing into the interior of the crucible from this glass phase, a temperature gradient then forms between the melt and the solidified layer. Within this temperature gradient is for most glasses, a temperature range in which the melt solidifies into glass or crystallized or partially crystallized.

If a particularly high heat removal can be achieved directly at the melt contact surface of the side wall, advantageously a dense, mechanically stable skull crust with a high polycrystalline content, which has a high heat reflectivity, is formed. As a result, the energy losses of the entire volume to be melted down can be minimized. With a comparatively low energy input for heating with respect to conventional skull crucibles, it is thus advantageously possible to achieve and maintain very high temperatures. In addition, the stable scull crust counteracts the abrasion caused by the melt, which also increases the long-term stability of the skull crucible.

It has been found that the relationships described above can be realized in particular if the limiting element comprises at least on its melt contact surface an at least partially structured surface. The structuring can be achieved for example by sandblasting or milling, in particular by Querriefenfräsen. In the context of the invention, however, all other methods for structuring the surface can be used. By structuring the surface on the melt contact surface of the limiting element, a very dense skull crust can form during operation of the skull crucible, which has a high heat reflectivity. The structured surface according to the invention comprises raised areas whose smallest dimension, in particular their width or their diameter, is of the order of millimeters or less.

At least on its melt contact surface, the delimiting element comprises a surface provided at least in regions with spaced-apart grooves. The spaced-apart grooves may be milled into the melt contact surface of the restriction member. The grooves may for example have a depth in the range of 0.01 mm to 2 mm, in particular from 0.05 mm to 1.5 mm, in particular from 0.1 mm to 1 mm, preferably a depth of 0.5 mm.

In a preferred embodiment of the invention it is provided that the distance between two spaced-apart grooves substantially coincides with the depth of the grooves. For example, the grooves may have a rectangular cross-section, so that they can be easily manufactured by machining processes.

Hardness and stability of the structured surface can advantageously be increased significantly in the case of a delimiting element comprising aluminum by providing the surface with an aluminum oxide layer by anodizing. Such a layer, even if extremely thin, has a high hardness and negligibly affects the heat transfer to the interior of the restriction member.

In the context of the invention it is provided that also the bottom plate has at least one channel arranged in its interior, which can be flowed through by a cooling medium. For example, several cooling circuits can be arranged in the bottom plate. In a preferred embodiment of the invention, the bottom plate has a surface-related cooling capacity, which substantially coincides with the area-related cooling capacity of the side wall of the skull crucible. Typical dissipated cooling capacities are in the range between 100 and 230 kW / m ² .

In the context of the invention is also provided that the bottom plate, in particular on its melt contact surface, is designed in the same way as the side walls. In particular, the melt contact surface of the bottom plate may have a structuring. The bottom plate can also be modular. The skull crucible according to the invention can be realized, in particular, with a large, universally usable base plate on which the side wall of a skull crucible is made available by setting up the delimiting elements whose bottom surface is a section of the entire base plate. With such a bottom plate advantageously with the help of the invention different sized Skulltiegel can be constructed quickly and flexibly with different cross sections.

With the skull crucible according to the invention, as stated above, melts can be provided which are substantially free from contamination by constituents of the crucible walls. After the melt has melted, however, it must be able to be fed to further processing. This means that the melt leaves the crucible. For this purpose, the invention advantageously provides the ability to remove the melt from the skull crucible so that the melt when removing almost only comes into contact with the Skullkruste to the above-described advantages of low contamination and high temperature in the enamel at least partially during removal to lose again.

The invention provides that the scull crucible comprises at least one valve, which allows stepless adjustments between the closed and fully opened state and thus also allows a stepless throughput regulation. The valve has an open and a closed condition for flowing a melt contained in the skull cup by transferring the valve from its closed to its open state from the skull cup, the valve having a coolable valve body. In particular, the valve may also include a coolable valve seat.

In a preferred embodiment, the valve seat is an integral part of the skull crucible, in particular the bottom plate of the skull crucible. If the valve assumes its closed state, the valve seat is cooled as part of the bottom plate. The valve body is cooled independently. The valve body closes off the opening in the bottom plate of the skull crucible, which is enclosed by the valve seat, at least to the extent that the melt completely freezes over the entire area and forms a dense skull crust. During operation, a scull crust forms in the interior of the skull crucible, which also adjoins the bottom plate, the valve seat and the valve body.

In the context of the invention, the valve can be designed, in particular, as a straight seat valve, in order to allow good operability and maintenance with uniform mechanical loading of the valve components. The valve seat may be formed in the invention in a preferred embodiment as a particular conical lateral surface of a passage opening in the bottom plate or a side wall of Skulltiegels. Also, the valve body may have an at least partially conical lateral surface.

The valve body may have a length L _VK , which is so large, in particular greater than the length of the passage opening L _O , that the valve body in the closed state of the valve partially from the passage opening in the bottom plate or the side wall of Skulltiegels out into the interior of the Skull crucible extends into it, so that during operation of the Skulltiegels a layer of solidified melt surrounds the protruding into the skull crucible part of the valve body. The layer of solidified melt surrounds the adjacent part of the valve of the bottom plate or the side wall of the skull crucible.

If melt is to be removed from the skull crucible, the valve can be opened by removing the valve body from the valve seat. The Skullschicht, which has formed in the closed state of the valve to the valve body and the valve body adjacent part of the bottom plate or the wall on the valve seat, initially remains. That is, in the first step of opening the valve, the valve body is removed from the valve seat and the skull layer prevents the melt from flowing through the valve. The hot melt in the interior of the skull crucible is in contact with the uncooled area of the skull crust, which was cooled by the valve body in the closed state of the valve. This area of the skull crust now melts. This leaves time to completely remove the valve body or place it in the correct position for the desired flow rate.

When the region has completely melted, the melt can flow out of the skull crucible between the valve seat and the valve body. A conical design of valve seat and valve body with a smaller on the melt contact surface dimension than at the existing on the outside of the skull crucible opening and the possibility of adjustment of the valve body relative to the valve seat allows the setting of the forming annular gap adjusting the flow rate. If the valve body to set the maximum possible throughput, for example, to drain the Skulltiegel completely removed, the conical shape of the valve seat ensures that the Skulltiegel leaving melt stream does not touch the lateral surface of the valve seat in the passage opening through the bottom plate or the Skulltiegelwand.

The melt is thus when removing from the Skulltiegel almost only with the scull crust, which surrounds the inlet opening in the valve seat, in contact. In the context of the invention, the scull crust melts in this type of removal, which is made possible by the valve according to the invention, solely by the contact with the melt. The use of thermal bridges, which would lead to a contamination of the melt, is not necessary in the context of the invention.

In a preferred embodiment, the skull crucible may comprise a positioning device to which the valve body can be releasably secured, wherein by means of the positioning of the valve body in relation to the valve seat in the direction of action of the valve is positionable, so that. He a first position in which the valve is closed is, at least one arbitrary intermediate position in which the valve is partially open and a second position in which the valve is fully open, occupy, wherein the projection of the valve body in the direction of action of the valve in the first position, in the intermediate position and in the second. Position of the valve body is at least partially congruent with the area defined by the valve seat. The positioning allows the defined positioning of the valve body to perform the removal operation described above. The valve body may for example be designed as a pin which is connected via a cooled and / or made of precious metal holder with the positioning, so that a movable holding device for the valve body is formed.

According to a preferred refinement, the positioning device may comprise a first displacement element, which is the displacement of the valve body in the effective direction of the valve, in particular the displacement perpendicular to the bottom plate or the side wall of Skulltiegels relative to the valve seat to open or close the valve or to change the flow through the valve allowed. If the valve is not fully opened, the volume flow of the glass flowing through the valve can be adjusted by adjusting the cross-section between the valve body and the valve seat. If the cooling of the valve body and / or the valve seat is thereby maintained, a scull crust can be formed on the valve body and / or the valve seat, so that the glass melt flowing through the partially opened valve is in contact almost exclusively with this scull crust.

The positioning device may further comprise a second displacement element, which allows the displacement of the valve body, in particular the displacement parallel to the bottom plate or the side wall of Skulltiegels relative to the valve seat, wherein the valve body has a third position in the direction of action outside the Skulltiegels and a fourth position outside the Skulltiegels , which is not in the direction of action of the valve, can take. In particular, the second displacement element may comprise a pivoting element with which the valve body can be pivoted from the third to the fourth and from the fourth to the third position.

The scull crucible can have a holder for the valve body, with which the valve body can be detachably fastened to the positioning device, in particular to the first and / or the second displacement element. The valve according to the invention may be controllable and / or controllable and / or adjustable, so that a defined throughput can be realized via the position of the valve body. If the throughput is to be greatly increased, for example in order to drain the skull crucible as quickly and completely as possible, the valve body can also be completely extended out of the valve seat and swung out.

As described above, the invention provides for constructing a skull crucible of limiting elements, which are mechanically connected to one another via rapidly detachable connections. In the case of inductive heating of the melted material in the skull crucible, the occurrence of arcs between the limiting elements must be prevented. This requires a high-frequency short circuit, but at the same time the rapid assembly and disassembly of the skull crucible should not be hindered.

To achieve this, it is provided in a preferred development that the skull crucible comprises at least one, in particular coolable, short-circuit ring. Depending on the height of the delimiting elements, in each case at least one separate continuous optionally cooled high-frequency short-circuit ring, which is preferably made of copper, can be arranged at one or both ends of the delimiting element. The individual plates made of solid material are detachably connected to these short-circuiting rings via electrically conductive connections in order to enable equipotential bonding over the entire melting vessel.

The individual plates of solid material are on the one hand by the contact via the pads and the mechanical connection, for example with screws, hooks, or similar components, electrically shorted together. However, this electrical short circuit is not defined, not the same and unstable in time at each contact surface. Thus, the contact resistance between each plate contact is different and this effect is enhanced in the course of a production cycle by the "working" of the melting vessel. The external, cooled and fixed to each plate segment fixed short-circuit ring, advantageously has a very low and also temporally stable contact resistance. Therefore, essentially all equalizing currents flow via this short-circuit ring.

Depending on the width of the individual segments of solid material, there may already be voltage differences within a segment, which should be reduced.

For this purpose, the skull segments, in particular from a width of 200 mm, can be connected according to the invention on both sides with the short-circuit ring.

The short-circuit ring may have at least one channel through which a cooling medium can flow. The short-circuit ring may in particular be arranged on the same side of the side wall of the skull crucible as the coolant supply device and the coolant discharge device of the delimiting element. The skull crucible may comprise a plurality, in particular two short-circuit rings, one being arranged in the upper third, in particular at the upper end, and one in the lower third, in particular at the lower end of the side wall. However, the invention can also be realized in a particularly simple manner by isolating all limiting elements used for the construction of the side wall against each other.

In particular, if only a short-circuit ring is used, it is advantageous to use an electrically insulated support device to support the mechanical stability of the then not short-circuited opposite side of the boundary elements. This support device is designed to be able to absorb the mechanical forces acting on the open ends of the individual limiting elements made of solid material. In particular, in the case of an inductive heating of the melting material, in which a high-frequency inductor is arranged around the skull crucible, the supporting device is positioned in the immediate vicinity of the electromagnetic heating field. It is therefore preferably designed so that there is no electrical short circuit on the extent to be supported.

The invention provides for the supporting device to have at least one first non-conductive insulating material, which in particular comprises plastic and / or ceramic and / or at least one composite material. In order to keep the thermal load of the first conductive insulating material as low as possible, the support device may comprise at least a second insulating layer, in particular a temperature-resistant ceramic filling compound, which is arranged between the limiting element and the first non-conductive insulating material. The ceramic filling compound may consist, for example, of a SiO ₂ -rich casting compound, of an Al ₂ O ₃ -rich casting composition, of a casting composition of an SiO ₂ / Al ₂ O ₃ mixture or other compositions of refractory materials.

In the context of the invention, however, the support device may also comprise a first conductive insulation material, which in particular comprises at least one metal and / or at least one conductive composite material. For example, the skull crucible may be configured such that a short-circuit ring is arranged in its lower region and a conductive support device in its upper region. In order to avoid a high-frequency short circuit, in the case of a supporting device with a conductive insulating material, provision is made for the supporting device to comprise at least one insulating element in order to avoid a short circuit. For example, a corresponding insulation point can be installed in the scope of the conductive support device.

In order to provide a skull crucible, in particular for melting and / or refining of glass available, which has a high mechanical strength even over long periods of time, and in which a contamination of the melt, which is treated in the crucible, due to corrosion in the Melt registered components of the crucible wall is largely avoided, which is structurally simple and can be flexibly adapted to different requirements of the melting process, and in which can form a stable, thickest possible skull crust on the metallic melt contact surface, the invention provides the Skulltiegel described above available. The stated objects are also achieved by a delimiting element, in particular a basic delimiting element or first extension delimiting element or second extension delimiting element for such a skull crucible. Also, a valve for such Skulltiegel contributes to the solution of the above tasks. The stated objects are also achieved with a method for melting and / or refining an inorganic substance, in particular glass, using the skull crucible according to the invention.

• a) Bereitstellen zumindest eines ersten und eines zweiten Grundbegrenzungselements sowie zumindest eines weiteren Begrenzungselements zum modularen Aufbau zumindest der Seitenwand eines Skulltiegels,
• b) Aufbau eines Skulltiegels durch Positionieren der Begrenzungselemente auf einer insbesondere kühlbaren Bodenplatte zum Ausbilden der Seitenwand des Skulltiegels,
• c) Positionieren zumindest einer Stützvorrichtung um die Seitenwand des Skulltiegels,
• d) Anlegen zumindest eines Kurzschlussrings um die Seitenwand des Skulltiegels,
• e) Anschließen der zumindest einen Kühlmittelzufuhreinrichtung und der zumindest einen Kühlmittelabfuhreinrichtung der Begrenzungselemente und gegebenenfalls der Bodenplatte an zumindest eine Kühlmittelversorgung, insbesondere an einen Kühlmittelkreislauf,
• f) Einlegen von Gemenge und/oder Scherben in den Skulltiegel,
• g) Beheizen des Gemenges und/oder der Scherben im Skulltiegel unter Entstehung einer Schmelze, wobei sich zumindest an den Seitenwänden eine Schicht aus erstarrtem Material abscheidet.

The inventive method for melting and / or refining an inorganic substance, in particular glass, in a preferred embodiment comprises the following steps:

• a) providing at least one first and one second basic limiting element and at least one further limiting element for the modular construction of at least the side wall of a skull crucible,
• b) construction of a skull crucible by positioning the limiting elements on a particularly coolable bottom plate for forming the side wall of the skull crucible,
• c) positioning at least one support device around the side wall of the skull crucible,
• d) applying at least one short-circuit ring around the side wall of the skull crucible,
• e) connecting the at least one coolant supply device and the at least one coolant discharge device of the delimiting elements and optionally the bottom plate to at least one coolant supply, in particular to a coolant circuit,
• f) placing mixtures and / or shards in the skull crucible,
• g) heating the mixture and / or the shards in Skulltiegel to form a melt, wherein at least on the side walls, a layer of solidified material is deposited.

• h) Verschieben des Ventilkörpers aus seiner ersten Position in seine Zwischenposition unter Aufhebung der Kühlung der zuvor über dem Ventilkörper entstandenen Schicht aus erstarrtem Material,
• i) Schmelzen der zuvor über dem Ventilkörper entstandenen Schicht aus erstarrtem Material und
• j) Entnehmen der Schmelze aus dem Skulltiegel

durchgeführt werden. In Schritt j) kann dabei ein durch die Ventilstellung in der Zwischenposition des Ventilkörpers definierter Volumenstrom an Schmelze aus dem Skulltiegel entnommen werden.The process can also be done with the following steps:

• h) displacing the valve body from its first position to its intermediate position while eliminating the cooling of the layer of solidified material previously formed above the valve body,
• i) melting the previously formed over the valve body layer of solidified material and
• j) Remove the melt from the skull crucible

be performed. In step j), a volume flow of melt defined by the valve position in the intermediate position of the valve body can be removed from the skull crucible.

• hh) Verschieben des Ventilkörpers aus seiner ersten Position in die zweite Position unter Aufhebung der Kühlung der zuvor über dem Ventilkörper entstandenen Schicht aus erstarrtem Material,
• k) Verschieben des Ventilkörpers aus der zweiten Position in die dritte Position, so daß der Ventilkörper parallel zur Seitenwand oder Bodenplatte verschieblich wird,
• l) Verschieben des Ventilkörpers aus der dritten Position in die vierte Position außerhalb des Skulltiegels,
• i) Schmelzen der zuvor über dem Ventilkörper entstandenen Schicht aus erstarrtem Material
• j) Entnehmen der Schmelze aus dem Skulltiegel

durchzuführen.For discharging the skull crucible, the invention offers the possibility of the method with the further steps:

• hh) displacing the valve body from its first position to the second position while eliminating the cooling of the previously formed over the valve body layer of solidified material,
• k) displacing the valve body from the second position to the third position, so that the valve body is displaceable parallel to the side wall or bottom plate,
• l) shifting the valve body from the third position to the fourth position outside the skull crucible,
• i) melting the previously formed over the valve body layer of solidified material
• j) Remove the melt from the skull crucible

perform.

In a preferred development, a skull crust is formed on the side walls in the method according to the invention by depositing a layer of solidified material on side walls, which has a total thickness measured perpendicular to the melt contact surface of greater than or equal to 1 mm to less than or equal to 12 mm, in particular of greater than or equal to 4 mm to less than or equal to 9 mm, in particular forms with a total thickness of 7 mm.

The layer of solidified material depositing on the side walls has, in a preferred embodiment, at least one first partial layer with an amorphous structure. The depositing layer of solidified material may additionally have at least one second partial layer with an at least partially crystalline structure. With a Skullkruste designed in this way, which is produced by the method according to the invention, a contamination of the melt by corrosion of the walls of Skulltiegels can be largely prevented. In addition, the layer of solidified material deposited on the sidewalls reflects heat radiation impinging on the inside of the skull crucible to a proportion of at least 25%.

The process according to the invention can be operated batchwise or continuously.

gekoppelt ist.The throughput V. Melted by the skull crucible can have a value in the range of greater than or equal to 2 kilograms a day, up to less than or equal to 50 tons a day. In particular, it is within the scope of the invention that in step b) of the method, a skull crucible is constructed, the melt occupied by the volume volume V _melt with the throughput V. and the mean residence time t _dwell on the context

is coupled.

The invention will be explained in more detail below with reference to the accompanying figures. The same components are denoted by the same reference numerals in all figures.

Show it

1 1 is a schematic representation of a plate of solid material according to a first embodiment of the invention in perspective view,

2 a schematic representation of the plate made of solid material according to the first embodiment of the invention in front view,

3 1 is a schematic representation of a plate made of solid material according to a second embodiment of the invention in perspective view,

4 1 is a schematic representation of a plate made of solid material according to a third embodiment of the invention in perspective view,

5 a schematic representation of an outbreak from the Skulltiegel according to the invention in cross section,

6 a schematic representation of a section of a side wall of Skulltiegels according to another embodiment of the invention in plan view,

7 a schematic representation of a skull crucible according to another embodiment of the invention in supervision,

8th a schematic representation of a section of a side wall of Skulltiegels in front view,

9 a schematic representation of the skull crucible according to the invention according to another embodiment of the invention in supervision,

10 a schematic representation of an enlarged section of the contact area between the surface of the plate of solid material and the melt with Skullkruste,

11 a photograph of the in 10 schematically illustrated transition region,

• – vollständig geschlossenes Ventil (1. Position) in 12A,
• – Zwischenposition zu einem Zeitpunkt t₁ in 12B,
• – Zwischenposition zu einem Zeitpunkt t₂ > t₁ in 12C,
• – zweite Position in 12D,
• – dritte Position in 12E,
• – vierte Position in 12F.

12 a schematic representation of a section of the Skulltiegel in another embodiment with a valve in cross section in different positions of the valve:

• - fully closed valve (1st position) in 12A .
• Intermediate position at a time t ₁ in 12B .
• Intermediate position at a time t ₂ > t ₁ in 12C .
• - second position in 12D .
• - third position in 12E .
• - fourth position in 12F ,

As in 1 is shown, there is the plate 24 made of solid material. That means that to manufacture the plate 24 a solid block of the material from which the plate is to be made, for example of aluminum or an aluminum alloy, is provided. This block is then processed by cutting processes, in particular by milling and drilling to the inventive design of the plate substantially. The plate 24 has a melt contact surface 25 , a floor area 26 which a footprint for the plate 24 forms an outer surface 27 and a first pad 208 and a second pad 209 , The plate 24 which may be part of a basic limiting element and in particular even the basic limiting element, is thus a compact unit.

The plate has a coolant supply device 7 and a coolant removal device 8th on. The coolant supply device 7 and the coolant removal device 8th stand with the inside of the plate 24 arranged channel 4 in contact. The channel 4 exists in the 1 shown example of a plurality of U-shaped individual channels, wherein the upper ends of these U-shaped individual channels in a trough-shaped depression of the upper end surface of the plate 24 end up. Through this trough-shaped depression, the individual channels can be manufactured, and by closing the trough-shaped depression with a correspondingly shaped closure element (not shown), a continuous channel 4 be created from adjoining U-shaped channels

The plate 24 has further devices 6 to provide a mechanical connection of delimiting elements to the plate 24 include, allow. In the example shown is a through hole 6 shown, can be made by a screw connection between two adjacent boundary elements.

2 shows the in 1 illustrated plate 24 in front view. The non-visible boundary lines drawn with dashed lines illustrate the course of the channel 4 inside the plate 24 and also show the edges of the pads 208 and 209 the plate 24 , Furthermore, the through holes 6 for one to see mechanical connection. Between the individual U-shaped channels, the plate 24 slots 211 on. Will the plate 24 used to build a Skulltiegels in which a melt is inductively heated, is through the slots 211 Ensure that no Faraday cage is formed.

In 3 is a plate 240 of solid material according to a second embodiment of the invention in perspective view. The plate 24 has a passage opening 95 on, which as a removal opening of Skulltiegels, which is a limiting element with a plate 240 has, can serve. Also the plate 240 has slots 211 on, which are arranged between U-shaped individual channels. The U-shaped individual channels form two in the interior of the plate in the second embodiment of the invention 240 arranged channels 4 , each with a coolant supply device 7 and a coolant discharge device 8th are connected. The plate 240 can through the two channels 4 be almost completely cooled by a cooling medium, although the plate is the through hole 95 includes.

In order to ensure as full as possible cooling the cooling channels 4 at the passage opening 95 be redirected in addition. To make this possible, additional deflection channels 41 Milled into the outside of the plate. These are then closed with appropriate glued, soldered or welded lids. For example, a precious metal system can be introduced into the through-hole for a glass removal. This system can be attached to four threaded holes 76 mechanically fastened.

The lateral surface 92 the through hole 95 but can also serve as a valve seat. A design according to the plate 240 can be used, for example, to form the bottom plate of a skull crucible. In this case could be on the slots 211 be waived. The plate 240 However, it can also be used to build the sidewall of a skull crucible. In particular, it is conceivable plates having a design according to the plate 24 and plates having a design according to the plate 240 to combine with each other. This can be done both by lateral juxtaposition of the plates, as well as by arranging different plates one above the other, which with the mechanical connections 6 can be interconnected.

Another embodiment of the solid material plate according to the invention is shown in FIG 4 shown. The plate 241 has compared to the plate 240 , which have a symmetrical construction with equidistant slots 211 has a construction in which the slots 211 in the area of the passage opening 95 have a greater distance from the respective adjacent slots than the slots 211 , which the passage opening 95 are not adjacent. The plate 241 in particular has a slot 211 on, passing through the passage opening 95 goes through it. The upper part of the plate 241 shows another embodiment of the around the passage opening 95 guided cooling channels 4 and their cooling medium supply 7 and 8th on. The second oblong milled cooling channel 46 serves to reduce the number of cooling medium connections. The plates 24 . 240 and 241 may be components of boundary elements that make up the sidewall 2 a skull crucible 1 can be built.

In 5 is an outbreak from a skull crucible 1 shown in cross section. The skull crucible 1 includes a cooled bottom plate 3 , which, as indicated by the arrows, is flowed through by a cooling medium. On the bottom plate 3 is partially an insulation layer 32 appropriate. On the insulation layer 32 stands the side wall 2 of the skull crucible 1 , The side wall 2 has a coolant supply device 7 , through which, as indicated by the arrow, the cooling medium in the side wall 2 can occur. There is a melt in the skull crucible 5 , which is heated inductively. For heating the melt 5 is one around the skull crucible 1 arranged coil 11 intended. The sink 11 may in particular be part of a heating device comprising a high-frequency inductor. The skull crucible 1 further includes a shorting ring 12 and a mechanical support device 13 passing through an insulation layer 14 from the side wall 2 is spaced.

The side wall 2 can be constructed in different ways from limiting elements according to the invention. In 6 is a section of a sidewall 2 according to an embodiment of the invention. The side wall 2 according to this embodiment comprises an area comprising a corner, wherein the corner is formed at the location at which two basic boundary elements 20 with their respective first connection surfaces 208 collide. To a basic boundary element 20 closes a first extension limiting element 21 at.

The second interface 209 of the basic boundary element 20 closes with the melt contact surface 25 of the basic boundary element 20 an angle β ₁ . The first connection surface 218 of the first extension limiting element 21 closes with the melt contact surface 25 of the first extension limiting element 21 an angle β ₂ . The following applies: β ₁ + β ₂ = 180 °. The first extension limiting element is for forming a straight wall 2 together with the basic boundary element 20 educated.

To the first extension delimiter 21 closes a second extension limiting element 22 at. The second interface 219 of the first extension limiting element 21 closes with the melt contact surface 25 of the first extension limiting element 21 an angle β ₃ . The first connection surface of the second extension-limiting element 228 . 22 closes with the melt contact surface 25 of the second extension limiting element 22 an angle β ₄ . The following applies: β ₃ + β ₄ = 180 °.

Also, the second extension limiting element is for forming a straight wall 2 formed together with the first extension limiting element. The second interface 229 of the second extension limiting element 22 especially with the melt contact surface 25 of the second extension limiting element 22 include an angle β ₁ . In the context of the invention, for example, the angle β ₃ = β ₁ can be selected. Thus, one comes with a kind of extension limiting elements.

In the example shown in 6 is the angle a, which is the first pad 208 of the basic boundary element 20 with the melt contact surface 25 of the basic boundary element 20 includes, 135 °. The abutting melt contact surfaces 25 the basic boundary elements 20 include an angle of 90 °.

According to another embodiment of the invention, a skull crucible 1 with a side wall 2 be built, which alone from basic boundary elements 200 consists. Such an arrangement is in 7 shown in supervision. The skull crucible 1 According to this further embodiment of the invention has a side wall 2 which defines an octagonal cross-section of the skull crucible. The side wall 2 This skull crucible consists of eight basic boundary elements 200 , The basic boundary elements have connection surfaces 208 , wherein a connection surface 208 a basic boundary element 200 to a connection surface 208 of the next basic boundary element 200 encounters. The angle a, which the connection surfaces 208 with the melt contact surface 25 of the basic boundary element 200 include, is 112.5 °.

Adjacent delimiting elements are used to form the side wall 2 of the skull crucible 1 mechanically interconnected.

8th shows a front view in the breakout of a skull crucible 1 , The side wall 2 of the skull crucible 1 includes a section, which consists of two plates 24 made of solid material. The plates 24 abut each other with their connection surfaces and are mechanically connected 6 connected with each other. The plates 24 stand on the floor plate 3 of the skull crucible 1 , being between the plates 24 and the bottom plate 3 an insulation layer 32 is introduced. The plates 24 each have a coolant inlet 7 and a coolant drain 8th on. In the field of mechanical connections 6 and the coolant supply device 7 or coolant removal device 8th , which are in the in 8th shown embodiment in the lower region of the plates 24 is an HF shorting ring 12 appropriate.

To stabilize the sidewall 2 of boundary elements with panels of solid material 24 includes the skull crucible 1 a mechanical support device 13 , which in the example shown in the upper part of the plates 24 is arranged. The support device 13 takes the mechanical shear forces on the open ends of each plate 24 Act on. As the support device 13 in close proximity to the electromagnetic heating field through the RF inductor 11 is positioned so that there is no electrical short circuit over the circumference to be supported.

In the embodiment shown, the support device 13 made of a non-conductive insulating material, which comprises plastic.

To preserve the necessary distance to hot areas is an isolation layer 14 from a temperature-resistant ceramic filling material or a temperature-resistant glass (for example silica glass or borosilicate glass) between the mechanical support device 13 and the outer wall 27 the plate 24 the side wall 2 arranged.

9 shows a plan view of a Skulltiegel according to another embodiment of the invention with a square cross-section. On the bottom plate 3 are four side walls 2 arranged, wherein the respective connection surfaces of the corners forming the basic boundary elements connect to corresponding connection surfaces of adjacent basic boundary elements. The geometry of the basic boundary elements is chosen so that they are within the size of the bottom plate 3 can be combined to any shape. The resulting shape of the sidewall 2 is determined by the shape of the basic boundary elements 20 certainly. In the example shown results in a rectangular shape. The square arrangement shown is the smallest possible arrangement of the basic boundary elements used 20 , which can be increased by using extension limiting elements.

As in the front view in 8th is shown in the embodiment shown there is the Height of the boundary elements equal for all boundary elements used. The invention provides limiting elements as a kit for the side wall 2 a skull crucible 1 to disposal. The height of the boundary elements for a kit is the same, since it has been found that the melting performance, that is per unit time meltable amount of mixture and / or shards heated even by direct inductive coupling electromagnetic waves or by direct electrical resistance heating Skulltiegel in essentially from the surface of the melt 5 depends, wherein the melt volume determines the total energy input into the melt and thus the maximum achievable temperature. By expanding the in 9 shown embodiment of Skulltiegels square cross section thus the surface of the molten bath can be increased.

The skull crucible 1 in the in 9 embodiment shown comprises in its side wall 2 a basic boundary element 20 which is a plate 240 . 241 with a passage opening 95 includes. At this passage opening 95 closes a sampling system 10 on, through which the melt 5 the further treatment can be supplied.

The basic boundary elements 20 that the side wall 2 Skulltiegels are each about their coolant supply 7 and coolant removal device 8th connected to a cooling system. Also the bottom plate 3 is coolant-cooled and has a cooling circuit (not shown).

Will the bottom plate 3 provided with the same specific cooling capacity as the side wall 2 , forms on the bottom plate 3 a much thicker skull crust than on the sidewall 2 , This is due to the structure of the entire skull crucible 1 and the selected heating. With electric heating forms in the middle of Skulltiegels 1 a core zone in which the highest temperatures in the melt 5 to rule. An upward convection flow transports there the heat from the core zone to the surface of the melt 5 , There, the heat is needed to melt the melt. The at the contact surfaces 25 the side wall 2 downward cold downward flow of the melt 5 on the other hand, it ensures cooling in the area of the melt 5 which is in the area of the ground 3 located. It therefore forms between core zone and bottom plate 3 a transition zone. For example, for low viscosity borate based optical glasses, the transition zone is typically 7-12 cm thick (for example, eight centimeters for N-LaSF44) in a melt vessel with 0.1 m ³ melt volume and a melt area of 1500 cm ² .

The relatively wide transition zone in turn promotes the formation of a particularly strong scull crust, which can be several centimeters thick. The skull crust may be in the area of the bottom plate 3 about ten times thicker than in the area of the sidewall 2 , To the energy loss by cooling the side wall 2 and the bottom plate 3 to minimize, according to the invention, the boundary elements of the side wall 2 and / or the bottom plate 3 with structured surfaces 28 Mistake.

In 10 is a comparison with the other representations enlarged section of the melt contact surface of a plate 24 made of solid material in contact with the cooling medium 40 and the melt 5 shown in the outbreak. The plate 24 has a structured surface 28 , which with the melt 5 is in contact, being between the melt 5 and the textured surface 28 a skull crust with the areas explained in more detail below 551 . 552 and 553 is trained. The plate 24 is over a cooling medium 40 cooled.

In the area of the small dimensions considered here, it has been found to maximize local heat extraction as much as possible in order to minimize the total energy loss of the skull crucible. Important for the energy and heat extraction of the melt 5 Among other things, the forming at the contact and transition zone skull layer and their reflectivity for thermal radiation. When crystals or crystalline materials are melted, a polycrystalline skull crust with a high heat reflectivity forms when the interfacial temperature is below the melting temperature of the material.

If glassy or semicrystalline materials are melted, on the other hand, there is no definite melting point below which the materials solidify in crystalline form. When melting glassy or semi-crystalline materials, it is therefore useful, by the highest possible local heat extraction in the range of these small dimensions, the interface temperature between melt 5 and melt contact surface of the plate 24 Lower as far as possible to bring the glass phase or the remaining glass phase as completely as possible to solidify. This forms in direct contact with the melt contact surface of the plate 24 the glassy layer 551 out.

In the overlying material layer 552 then forms a temperature gradient between melt 5 and solidified glassy layer 551 out. Within this temperature gradient is also present for the vast majority of glasses crystallization between melt 5 and solidified glass 551 , The result of high heat extraction in the immediate boundary layer 551 between melt 5 and melt contact surface of the plate 24 is a dense, mechanically stable skull crust with the highest possible crystalline content, which has a particularly high heat reflectivity. The layer 552 is thus a partially crystalline or fully crystalline layer, which with the glassy layer 551 in contact.

Due to the high heat reflectivity of the melt contact surface 25 the side wall 2 or at the contact surface to the bottom plate 3 forming Skullkruste can the energy losses of the entire volume of melt 5 be minimized. Thus, maximum temperatures in the melt can be achieved with minimum energy input 5 be achieved. In addition, the stable scull crust counteracts abrasion through the melt, so that the long-term stability of the skull crucible 1 is increased. To the semi-crystalline or fully crystalline mechanically hard layer 552 closes a semi-crystalline in the melting increasingly softening layer 553 as a transition zone between the scull crust and the melt 5 at.

The formation of such a stable skull crust is promoted by structuring the melt contact surface. By the melt contact surface 25 a structured surface 28 In particular, the value for the entire surface is increased in relation to an unstructured surface, so that the removal of heat and thus the formation of a glassy layer 551 is encouraged. In the in 10 embodiment shown has the structured surface 28 groove 281 on.

In 11 is the in 10 schematically illustrated Skullkruste shown by a photograph. You can clearly see the different layers 551 . 552 and 553 the skull crust 55 , which has a total thickness of about 12 mm.

Especially in the area of the bottom plate 3 training skull crust 55 offers in the context of the invention the possibility of removing the melt 5 from the skull crucible 1 perform such a way that the melt 5 essentially not with the materials of the sidewalls 2 or the bottom plate 3 comes into contact. The basis of the illustrations in 12 below described removal of the melt 5 through a valve 9 which is in the bottom plate 3 is arranged in the context of the invention can also be realized with a valve which in the side wall 2 of the skull crucible 1 is arranged.

In 12A is the valve 9 shown in its fully closed first position. The valve 9 includes a valve body 91 and a valve seat 92 , The valve 9 seals the opening in the bottom plate 3 opposite the melt 5 from. The valve body 91 is designed as a conical pin, which at least one cooling channel 94 having. The valve body 91 protrudes in the closed position of the valve 9 in operation in the area of the melt 5 into it, with a scull crust 55 which forms into the melt 5 protruding part of the valve body 91 as well as to the valve 9 adjoining areas of the floor slab 3 coats. The valve seat 92 is an integral part of the bottom plate in the example shown 3 , The valve body 91 is via a connection, not shown, with a cooled or uncooled positioning 93 connected. The positioning device 93 allows in particular the positioning of the valve body 91 along the effective direction 90 of the valve 9 ,

In 12B is the valve 9 shown in its intermediate position at a time t ₁ , in which the valve body 91 by shifting from the first position along the direction of action 90 the valve to cancel the contact between the valve body 91 and valve 92 with the help of the positioning device 93 was brought. The contact between the cooled valve body 91 and the skull crust 55 is canceled in the intermediate position at time t ₁ . At a time t ₂ > t ₁ is due to the now lack of cooling the skull crust 55 the area in the first position of the valve in contact with the cooled valve body 91 stood, melted. The valve is in control position.

Through the gap between the valve body 91 and the valve seat 92 can the melt 5 leave the skull crucible, with the melt 5 while largely in contact with the skull crust 55 on the bottom plate 3 of the skull crucible 1 stands. The vertical position of the valve body 91 determines the size of the annular gap between the valve body 91 and valve seat 92 and thus determines the flow rate through the valve.

The valve 9 can with respect to the control position by further process of the valve body 91 with the help of the positioning device 93 along the effective direction 90 of the valve are brought into a fully open second position. In the second position of the valve 9 is the valve body 91 with its entire length from the valve seat 92 moved out.

The dimensions of valve body 91 and valve seat 92 or passage opening in the bottom plate 3 are in the 12E dimensioned. The valve body 91 has a length L _VK and the passage opening at which the valve seat 92 located in the bottom plate 3 has a length L _O , which is smaller than the length L _VK to the in 12A illustrated position of the valve in closed form with in the melt 5 protruding valve body 91 to enable.

In the in 12E shown third position of the valve is the valve body 91 in the direction of action 90 of the valve 9 outside the skull crucible 1 spaced from the bottom plate 3 of the skull crucible 1 positioned. From this third position, the valve body can 91 completely out of the melt area 5 be moved out, leaving a fourth position outside the skull crucible 1 that does not take effect 90 the valve is located. This fourth position of the valve is in 12F shown. The positioning device 93 is formed such that it the valve body 91 in the example shown here perpendicular to the effective direction 90 of the valve 9 can move.

This can be done in particular by pivoting the valve body 91 happen. The in 12F cross-section through the valve and the surrounding areas of the melt and Skullkruste shown can therefore an angle> 0 ° with the in 12E include illustrated cross-section.

The in the 12A to 12F illustrated movement of the valve body from the first position on the intermediate position to the second and third and from there to the fourth position can be carried out very quickly in practice, so that in particular the fourth position is reached before the Skullkruste located in the first Position of the valve above that there from the valve body 91 closed valve seat has formed, melts. In the 12A to 12F Stations of a slow opening of the valve were presented.

In the case of the very rapid opening of the valve, which is carried out according to a further embodiment, the valve body is never in contact with the skull crucible in the intermediate position until reaching the fourth position 1 outflowing glass melt 5 ,

Within the scope of the invention, the features described above with respect to individual embodiments may be combined and interchanged.

LIST OF REFERENCE NUMBERS

1

skull crucible

2

Sidewall of skull crucible

20, 200

Basic limiting element

21

first extension limiting element

22

second extension limiting element

24, 240, 241

Plate made of solid material

25

Melt contact surface

26

floor area

27

outer surface

28

structured surface

281

groove

208

first connection surface of the basic boundary element

209

second connection surface of the basic boundary element

218

first pad of the first extension limiting element

219

second pad of the first extension limiting element

228

first pad of the second extension limiting element

229

second pad of the second extension limiting element

211

slot

3

Bottom plate of skull crucible

32

insulation layer

4

channel

40

cooling medium

41

diversion channel

46

elongated cooling channel

5

melt

55

Skull crust, frozen layer

551

glassy layer

552

semi-crystalline or fully crystalline layer

553

semi-crystalline layer, transition zone

6

mechanical connection

7

Coolant feeder

76

mounting holes

8th

Coolant discharge device

9

Valve

90

Effective direction of the valve

91

valve body

92

valve seat

93

positioning

94

Cooling channel of the valve

95

Through opening

10

Extraction device, removal system

11

RF inductor

12

Shorting ring

13

support device

14

insulating

Claims (67)

Skull crucible ( 1 ), in particular for melting and / or refining glass, which at least one coolable side wall ( 2 ) and at least one bottom plate ( 3 ), wherein the side wall ( 2 ) at least a first and a second basic boundary element ( 20 . 200 ) comprising a plate ( 24 . 240 . 241 ) made of solid material, which has a substantially flat melt contact surface ( 25 ) a floor surface ( 26 ) for setting up the basic boundary element ( 20 . 200 ) on the bottom plate ( 3 ), an outer surface ( 27 ) and a first and a second pad ( 208 . 209 ), wherein at least the first connection surface ( 208 ) of the first basic boundary element ( 20 . 200 ) complementary to at least one pad ( 209 ) of the second basic boundary element ( 20 . 200 ) is formed around the first basic limiting element ( 20 . 200 ) to the second basic boundary element ( 20 . 200 ) for building at least a part of the side wall ( 2 ) of the skull crucible ( 1 ), in particular to form a positive connection, connect the plate ( 24 . 240 . 241 ) at least one channel disposed in its interior ( 4 ), which of a cooling medium ( 40 ) can be flowed through, and wherein the limiting element at least at its melt contact surface ( 25 ) comprises an at least partially structured surface with spaced-apart grooves. Skull crucible ( 1 ) according to claim 1, characterized in that the skull crucible ( 1 ) at least one further delimiting element ( 21 . 22 ) to the modular structure of the side wall ( 2 ) of the skull crucible ( 1 ), wherein the boundary elements ( 20 . 21 . 22 ) mutually complementary connection surfaces ( 208 . 209 . 218 . 219 . 228 . 229 ) exhibit. Skull crucible ( 1 ) according to claim 1 or 2, characterized in that the boundary elements ( 20 . 200 . 21 . 22 ) detachable to one another, in particular by means of at least one mechanical connection ( 6 ), in particular at least one screw connection and / or at least one plug connection, are connectable. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) at least a first extension limiting element ( 21 ) comprising a plate ( 24 . 240 . 241 ) made of solid material, which has a substantially flat melt contact surface ( 25 ), a floor surface ( 26 ) for placing the first extension-limiting element on the bottom plate ( 3 ), an outer surface ( 27 ) and a first and a second pad ( 218 . 219 ), wherein at least the first connection surface ( 218 ) of the first extension delimiting element ( 21 ) complementary to at least one pad ( 208 . 209 ) of a basic boundary element ( 20 . 200 ) is formed around the first extension limiting element ( 21 ) to a basic boundary element ( 20 . 200 ) for building at least a part of the side wall ( 2 ) of the skull crucible ( 1 ), in particular to form a positive connection to connect, and wherein the plate ( 24 . 240 . 241 ) at least one channel disposed in its interior ( 4 ), which of a cooling medium ( 40 ) can be flowed through. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) at least one second extension limiting element ( 22 ) comprising a plate ( 24 . 240 . 241 ) made of solid material, which has a substantially flat melt contact surface ( 25 ), a floor surface ( 26 ) for setting up the second extension delimiting element ( 22 ) on the bottom plate ( 3 ), an outer surface ( 27 ) and a first and a second pad ( 228 . 229 ), wherein the first connection surface ( 228 ) of the second extension limiting element ( 22 ) complementary to the second pad ( 219 ) of the first extension limiting element ( 21 ), and wherein the second connection surface ( 229 ) of the second extension limiting element ( 22 ) complementary to the first pad ( 228 ) of a further second extension limiting element ( 22 ) is formed to the second extension-limiting element ( 22 ) to a first and / or to another second extension limiting element ( 21 . 22 ) for building at least a part of the side wall ( 2 ) of the skull crucible ( 1 ), in particular to form a positive connection to connect, and wherein the plate ( 24 . 240 . 241 ) at least one channel disposed in its interior ( 4 ), which of a cooling medium ( 40 ) can be flowed through. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the second connection surface ( 219 ) of the first extension limiting element ( 21 ), the first pad ( 228 ) of the second extension limiting element ( 22 ) and the second pad ( 229 ) of the second extension limiting element ( 22 ) with the melt contact surface ( 25 ) of the respective delimiting element ( 21 . 22 ) enclose an angle of 90 °. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the second interface ( 209 ) of the basic boundary element ( 20 . 200 ) with the melt contact surface ( 25 ) of the basic boundary element ( 20 . 200 ) includes an angle β ₁ , and the first pad ( 218 ) of the first extension limiting element ( 21 ) with the melt contact surface ( 25 ) of the first extension limiting element ( 21 ) includes an angle β ₂ , where β ₁ + β ₂ = 180 °. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the second connection surface ( 219 ) of the first extension limiting element ( 21 ) with the melt contact surface ( 25 ) of the first extension limiting element ( 21 ) includes an angle β ₃ , and the first pad ( 228 ) of the second extension limiting element ( 22 ) with the melt contact surface ( 25 ) of the second extension limiting element ( 22 ) includes an angle β ₄ , where β ₃ + β ₄ = 180 °. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) has a cross section in the form of a polygon with a number N at corners, and the basic boundary elements ( 20 . 200 ) are designed such that when connecting a basic limiting element ( 20 . 200 ) to another basic boundary element ( 20 . 200 ) a corner of the polygonal cross section of the skull crucible ( 1 ) is formed. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) has an octagonal cross-section. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) has a quadrangular cross-section. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) has an equilateral cross-section. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that at least one connection surface ( 208 . 209 ) of a basic boundary element ( 20 . 200 ) with the melt contact surface ( 25 ) an angle α with α = (1 + 2 / N) · 90 ° includes. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the limiting element ( 20 . 200 . 21 . 22 ) has a height H _W and during operation of the skull crucible ( 1 ) with its melt contact surface ( 25 ) to a height H _S measured from the bottom of the limiting element with a melt ( 5 ), which are in the Skulltiegel ( 1 is in contact, where H _S <H _W , and at least in its melt contact surface ( 25 ) in the area up to H _S free of joints, in particular free of welds and / or solder joints and / or glued joints and / or friction joints and / or form-locking connections and / or screw is. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the limiting element has a height H _W , which has a value in the range of greater than or equal to 10 cm to less than or equal to 1.5 m, in particular in the range of greater than or equal to 50 cm to smaller or equal to 1.0 m. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the melt ( 5 ) in the skull crucible ( 1 ) ingestible volume, which is the product of the height H _S and that of the side wall ( 2 ) enclosed surface of the bottom plate ( 3 ), has a value in the range of greater than or equal to 0.005 m ³ to less than or equal to 0.3 m ³ . Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the limiting element ( 20 . 200 . 21 . 22 ) comprises a metal or a metal alloy, in particular platinum, preferably aluminum and / or an aluminum alloy. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the plate ( 24 . 240 . 241 ) as in its interior arranged channel ( 4 ), which of a cooling medium ( 40 ) can be flowed through, at least includes a blind hole. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the plate ( 24 . 240 . 241 ) in its interior at least one U-shaped channel ( 4 ), which of a cooling medium ( 40 ) can be flowed through. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the limiting element ( 20 . 200 . 21 . 22 ) at least one coolant supply device ( 7 ) and at least one coolant removal device ( 8th ), which in particular on the same side of the limiting element ( 20 . 200 . 21 . 22 ) are arranged. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the Plate ( 24 . 240 . 241 ) and / or the bottom plate ( 3 ) comprises at least one slot, so that the plate ( 24 . 240 . 241 ) and / or the bottom plate ( 3 ) can be penetrated by an electromagnetic field. Skull crucible ( 1 ) according to claim 1, characterized in that the spaced apart grooves in the melt contact surface ( 25 ) of the boundary element are milled. Skull crucible ( 1 ) according to claim 22, characterized in that the spaced-apart grooves have a depth of in the range of 0.01 mm to 2 cm, in particular from 0.05 mm to 0.5 cm, in particular from 0.1 mm to 1 mm have a depth of 0.5 mm. Skull crucible ( 1 ) according to any one of claims 22 to 23, characterized in that the distance of each two spaced-apart grooves substantially coincides with the depth of the grooves. Skull crucible ( 1 ) according to one of claims 22 to 24, characterized in that the spaced-apart grooves have a rectangular cross-section. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the limiting element at least on its melt contact surface ( 25 ) at least partially a metal oxide layer, which comprises in particular Al ₂ O ₃ . Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the bottom plate ( 3 ) at least one channel disposed in its interior ( 4 ), which of a cooling medium ( 40 ) can be flowed through. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the bottom plate ( 3 ) has a surface-related cooling capacity, which substantially with the area-related cooling capacity of the side wall ( 2 ) of the skull crucible ( 1 ) matches. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) at least one valve ( 9 ) with a valve body ( 91 ) and a valve seat ( 92 ), which has an open and a closed state, to form a melt ( 5 ), which are in the Skulltiegel ( 1 ) by transferring the valve ( 9 ) from its closed to its open state from the Skulltiegel ( 1 ), whereby the valve ( 9 ) a coolable valve body ( 91 ) having. Skull crucible ( 1 ) according to claim 29, characterized in that the valve seat ( 92 ) integral part of the skull crucible ( 1 ), in particular the bottom plate ( 3 ) of the skull crucible ( 1 ) is. Skull crucible ( 1 ) according to one of claims 29 or 30, characterized in that the valve ( 9 ) is a straight seat valve. Skull crucible ( 1 ) according to one of claims 29 to 31, characterized in that the valve seat ( 92 ) as, in particular conical, lateral surface of a passage opening ( 95 ) in the bottom plate ( 3 ) or a side wall ( 2 ) of the skull crucible ( 1 ) is trained. Skull crucible ( 1 ) according to one of claims 29 to 32, characterized in that the valve body ( 91 ) has an at least partially conical lateral surface. Skull crucible ( 1 ) according to one of claims 29 to 33, characterized in that the valve body ( 91 ) has a length L _VK , which is so large, in particular greater than the length L _{O of} the passage opening ( 95 ), is that the valve body ( 91 ) in the closed state of the valve ( 9 ) partly from the passage opening ( 95 ) in the bottom plate ( 3 ) or the side wall ( 2 ) of the skull crucible ( 1 ) out into the skull of the skull ( 1 ), so that during operation of the skull crucible ( 1 ) a layer of solidified melt ( 55 ) into the skull crucible ( 1 ) protruding part of the valve body ( 91 ) surrounds. Skull crucible ( 1 ) according to one of claims 29 to 34, characterized in that the skull crucible ( 1 ) a positioning device ( 93 ), on which the valve body ( 91 ) can be releasably secured, wherein by means of the positioning ( 93 ) the valve body ( 91 ) in relation to the valve seat ( 92 ) in the direction of action ( 90 ) of the valve ( 9 ) is positionable so that it has a first position in which the valve ( 9 ) is closed, an intermediate position in which the valve ( 9 ) is partially open, and a second position in which the valve ( 9 ) is fully open, can take, wherein the projection surface of the valve body ( 91 ) in the direction of action ( 90 ) of the valve ( 9 ) in the first position, in the intermediate position and in the second position of the valve body ( 91 ) at least partially with the through the valve seat ( 92 ) defined surface is congruent. Skull crucible ( 1 ) according to claim 35, characterized in that the positioning device ( 93 ) comprises a first displacement element, which is the Moving the valve body in the direction of action ( 90 ) of the valve ( 9 ), in particular the displacement perpendicular to the bottom plate ( 3 ) or the side wall ( 2 ) of the Skultiegel ( 1 ), relative to the valve seat ( 92 ) for opening or closing the valve ( 9 ) or to change the flow through the valve ( 9 ) allowed. Skull crucible ( 1 ) according to one of claims 35 or 36, characterized in that the positioning device ( 93 ) comprises a second displacement element which controls the displacement of the valve body ( 91 ), in particular the displacement parallel to the bottom plate ( 3 ) or the side wall ( 2 ) of the Skultiegel ( 1 ), relative to the valve seat ( 92 ), wherein the valve body ( 91 ) a third position in the direction of action ( 90 ) outside the skull crucible ( 1 ) and a fourth position outside the skull crucible ( 1 ) that are not working ( 90 ) is the valve, can take. Skull crucible ( 1 ) according to claim 37, characterized in that the second displacement element comprises a pivoting element, with which the valve body ( 91 ) can be pivoted from the third to the fourth and from the fourth to the third position. Skull crucible ( 1 ) according to one of claims 29 to 38, characterized in that the valve ( 9 ) is controllable and / or controllable and / or adjustable. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) at least one, in particular coolable, short-circuit ring ( 12 ). Skull crucible ( 1 ) according to claim 40, characterized in that the short-circuit ring ( 12 ) at least one channel ( 4 ), which of a cooling medium ( 40 ) can be flowed through. Skull crucible ( 1 ) according to one of claims 40 or 41, characterized in that the short-circuit ring ( 12 ) Comprises copper. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) at least one electrically conductive connection for releasably securing the short-circuit ring ( 12 ) on at least one boundary element ( 20 . 200 . 21 . 22 ). Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the short-circuit ring ( 12 ) on the same side of the side wall ( 2 ) of the skull crucible ( 1 ) is arranged as coolant supply device ( 7 ) and coolant removal device ( 8th ) of the delimiting element ( 20 . 200 . 21 . 22 ). Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) two short-circuit rings ( 12 ), one in the upper third and one in the lower third of the side wall ( 2 ) is arranged. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that all for the construction of the side wall ( 2 ) limiting elements ( 20 . 21 . 22 . 200 ) are electrically isolated from each other. Skull crucible ( 1 ) according to one of the preceding claims, characterized in that the skull crucible ( 1 ) a supporting device ( 13 ) for the side wall ( 2 ). Skull crucible ( 1 ) according to claim 47, characterized in that the supporting device ( 13 ) electrically opposite the skull crucible ( 1 ) is isolated. Skull crucible ( 1 ) according to claim 47 or 48, characterized in that the supporting device ( 13 ) comprises at least one first electrically non-conductive insulating material, which in particular comprises plastic and / or ceramic and / or at least one electrically nonconductive composite material. Skull crucible ( 1 ) according to one of claims 47 to 49, characterized in that the supporting device ( 13 ) at least one second electrical insulating layer ( 14 ), in particular a temperature-resistant ceramic filling compound, which comprises between the delimiting element ( 20 . 200 . 21 . 22 ) and the supporting device ( 13 ), in particular the first electrically non-conductive insulating material is arranged. Skull crucible ( 1 ) according to one of claims 47 to 50, characterized in that the supporting device ( 13 ) comprises at least one first electrically conductive insulating material, which in particular comprises at least one metal and / or at least one electrically conductive composite material. Skull crucible ( 1 ) according to one of claims 47 to 51, characterized in that the supporting device ( 13 ) comprises at least one electrical insulating element to avoid a short circuit. Basic limiting element ( 20 . 200 ) which is used to construct at least part of a coolable side wall ( 2 ) of a skull crucible ( 1 ) is formed according to one of claims 1 to 52, wherein the basic limiting element ( 20 . 200 ) a plate ( 24 . 240 . 241 ) made of solid material, which has a substantially flat melt contact surface ( 25 ), a floor surface ( 26 ) to set up the Basic boundary element ( 20 . 200 ) on a bottom plate ( 3 ) of the skull crucible ( 1 ), an outer surface ( 27 ) and a first and a second pad ( 208 . 209 ), wherein at least the first connection surface ( 208 ) of the first basic boundary element ( 20 . 200 ) complementary to at least one pad ( 209 ) of the second basic boundary element ( 20 . 200 ) is formed around the first basic limiting element ( 20 . 200 ) to the second basic boundary element ( 20 . 200 ) for building at least a part of the side wall ( 2 ) of the skull crucible ( 1 ), in particular to form a positive connection, connect the plate ( 24 . 240 . 241 ) at least one channel disposed in its interior ( 4 ), which of a cooling medium ( 40 ) can be flowed through, and wherein the basic limiting element at least at its melt contact surface ( 25 ) comprises an at least partially structured surface with mutually spaced grooves. First extension limiting element ( 21 ) which is used to construct at least part of a coolable side wall ( 2 ) of a skull crucible ( 1 ) according to one of claims 1 to 52 in combination with a basic limiting element ( 20 . 200 ) according to claim 53 and a plate ( 24 . 240 . 241 ) made of solid material, which has a substantially flat melt contact surface ( 25 ), a floor surface ( 26 ) for placing the first extension limiting element on a base plate ( 3 ) of the skull crucible ( 1 ), an outer surface ( 27 ) and a first and a second pad ( 218 . 219 ), wherein at least the first connection surface ( 218 ) of the first extension delimiting element ( 21 ) complementary to at least one pad ( 208 . 209 ) of a basic boundary element ( 20 . 200 ) is formed around the first extension limiting element ( 21 ) to a basic boundary element ( 20 . 200 ) for building at least a part of the side wall ( 2 ) of the skull crucible ( 1 ), in particular to form a positive connection to connect, and wherein the plate ( 24 . 240 . 241 ) at least one channel disposed in its interior ( 4 ), which of a cooling medium ( 40 ), and wherein the first extension element at least on its melt contact surface ( 25 ) comprises an at least partially structured surface with spaced-apart grooves. Second extension element ( 22 ) which is used to construct at least part of a coolable side wall ( 2 ) of a skull crucible ( 1 ) according to one of claims 1 to 52 in combination with a first extension element ( 21 ) is formed according to claim 54 and which a plate ( 24 . 240 . 241 ) made of solid material, which has a substantially flat melt contact surface ( 25 ), a floor surface ( 26 ) for setting up the second extension delimiting element ( 22 ) on a bottom plate ( 3 ) of the skull crucible ( 1 ), an outer surface ( 27 ) and a first and a second pad ( 228 . 229 ), wherein the first connection surface ( 228 ) of the second extension limiting element ( 22 ) complementary to the second pad ( 219 ) of the first extension limiting element ( 21 ), and wherein the second connection surface ( 229 ) of the second extension limiting element ( 22 ) complementary to the first pad ( 228 ) of a further second extension limiting element ( 22 ) is formed to the second extension-limiting element ( 22 ) to a first and / or to another second extension limiting element ( 21 . 22 ) for building at least a part of the side wall ( 2 ) of the skull crucible ( 1 ), in particular to form a positive connection to connect, and wherein the plate ( 24 . 240 . 241 ) at least one channel disposed in its interior ( 4 ), which of a cooling medium ( 40 ), and wherein the second extension element at least at its melt contact surface ( 25 ) comprises an at least partially structured surface with spaced-apart grooves. Skull crucible ( 1 ) with a valve ( 9 ), which has a valve body ( 91 ) and a valve seat ( 92 ) and has an open and a closed state to a melt ( 5 ), which are in the Skulltiegel ( 1 ) by transferring the valve ( 9 ) from its closed to its open state from the Skulltiegel ( 1 ), whereby the valve ( 9 ) a coolable valve body ( 91 ) and the valve seat ( 92 ) integral part of the skull crucible ( 1 ), in particular the bottom plate ( 3 ) of the skull crucible ( 1 ) is. Method for melting and / or refining an inorganic substance, in particular glass, using a skull crucible according to one of claims 1 to 52, comprising the following steps: a) providing at least one first and one second basic limiting element ( 20 . 200 ) and at least one further delimiting element ( 21 . 22 ) to the modular construction of at least the side wall ( 2 ) of a skull crucible ( 1 ) b) Construction of a skull crucible ( 1 ) by positioning the boundary elements ( 20 . 200 . 21 . 22 ) on a coolable bottom plate ( 3 ) for forming the side wall ( 2 ) of the skull crucible ( 1 ), c) positioning at least one supporting device ( 13 ) around the side wall ( 2 ) of the skull crucible ( 1 ), d) applying at least one short-circuit ring ( 12 ) around the side wall ( 2 ) of the skull crucible ( 1 ), e) connecting the at least one coolant supply device ( 7 ) and the at least one coolant removal device ( 8th ) of the delimiting elements ( 20 . 200 . 21 . 22 ) and the bottom plate ( 3 ) to at least one coolant supply, in particular to a coolant circuit, f) introduction of mixtures and / or shards into the skull crucible ( 1 g) heating the mixture and / or the broken pieces in the skull crucible ( 1 ) with formation of a melt ( 5 ), at least on the side walls ( 2 ), in particular also on the bottom plate ( 3 ), a layer ( 55 ) deposited from solidified material and located on the side walls ( 2 ) depositing layer ( 55 ) of solidified material from within the skull crucible ( 1 ) reflects incident heat radiation to a level of at least 25%. Method according to claim 57 with the further steps h) displacement of the valve body ( 91 ) from its first position to its intermediate position with the cancellation of the cooling above the valve body ( 91 ) layer ( 55 ) of solidified material, i) melting the previously above the valve body ( 91 ) layer ( 55 ) of solidified material, j) removal of the melt ( 5 ) from the skull crucible ( 1 ). A method according to claim 58, characterized in that in step j) a by the valve position in the intermediate position of the valve body ( 91 ) defined volume flow of melt ( 5 ) is taken. Method according to one of claims 57 to 59 with the further steps hh) displacement of the valve body ( 91 ) from its first position to the second position with the cancellation of the cooling above the valve body ( 91 ) layer ( 55 ) of solidified material, k) displacement of the valve body ( 91 ) from the second position to the third position, so that the valve body ( 91 ) parallel to the side wall ( 2 ) or bottom plate ( 3 ) is displaceable, l) displacement of the valve body ( 91 ) from the third position to the fourth position outside the skull crucible ( 1 ), i) melting the previously above the valve body ( 91 ) layer ( 55 ) of solidified material, j) removal of the melt ( 5 ) from the skull crucible ( 1 ). Method according to one of claims 57 to 60, characterized in that at least on the side walls ( 2 ) depositing layer ( 55 ) of solidified material has a total thickness perpendicular to the melt contact surface ( 25 ) of greater than or equal to 1 mm to less than or equal to 12 mm, in particular of greater than or equal to 4 mm to less than or equal to 9 mm, in particular of 7 mm. Method according to one of claims 57 to 61, characterized in that at least on the side walls ( 2 ) depositing layer ( 55 ) of solidified material at least a first sub-layer ( 551 ) having an amorphous structure. Method according to one of claims 57 to 62, characterized in that at least on the side walls ( 2 ) depositing layer ( 55 ) of solidified material at least a second sub-layer ( 552 . 553 ) having an at least partially crystalline structure. Method according to one of claims 57 to 63, characterized in that the throughput V. on melt ( 5 ) through the skull crucible ( 1 ) has a value ranging from greater than or equal to 2 kg / day to less than or equal to 50 tons / day. Method according to one of claims 57 to 64, characterized in that in b) of the method a Skulltiegel ( 1 ) is built, whose from the melt ( 5 ) occupied volume V _melt with the throughput V. and the mean residence time t _Vervweil about the context

is coupled. Method according to one of claims 57 to 65, characterized in that the method is operated continuously. Method according to one of claims 57 to 65, characterized in that the method is operated discontinuously.

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