Safety device, glass melting plant and glass articles

Abstract

Safety device for receiving a glass melting tank suitable for preparing, processing and / or holding molten glass, the safety device comprising: at least one wall, wherein the wall comprises several wall elements and at least partially limits a volume into which the glass melting furnace can be accommodated, wherein the wall elements each have at least one channel system through which at least one fluid can flow; and at least one electrode feedthrough, wherein at least one electrode feedthrough is jointly provided and / or formed by two or more of the wall elements, wherein at least one electrode can be inserted from the outside through the wall element into the volume which is at least partially limited by the wall by means of the electrode feedthrough, wherein the electrode feedthrough includes at least a first electrical insulation by means of which the electrode passed through the electrode feedthrough is electrically insulated from the wall element, the channel system and / or the fluid flowing therein.

Description

[0001] The present invention relates to a safety device for holding a glass melting tank suitable for preparing, processing, and / or holding molten glass. The present invention also relates to a glass melting plant comprising such a safety device and a glass melting tank for preparing, processing, and / or holding molten glass. Furthermore, the invention relates to glass articles that are manufactured or can be manufactured using such a glass melting plant. State of the art

[0002] In glass production, glass is melted in a suitable device called a glass melting furnace. These furnaces can hold a volume of molten glass and are now primarily made of ceramic refractory materials. However, these materials are subject to constant corrosion when in contact with the hot molten glass, leading to a continuous decrease in the thickness of the refractory material in the furnace. When the remaining material thickness falls below a defined minimum, the entire system must be taken out of service and repaired, specifically by replacing the refractory material.

[0003] In the worst-case scenario, however, the optimal time to shut down the system is missed, resulting in an unwanted release of molten glass from the melting furnace. This can cause significant damage to the production periphery and infrastructure, and also pose a serious fire hazard. Not to mention the potential for personal injury. Apart from close, continuous visual monitoring of the refractory material's thickness, no other methods are currently known to reliably prevent the risk of molten glass leakage. Existing technical solutions have only provided limited, localized protection, or deliver results that are too imprecise and therefore ultimately unreliable.

[0004] To at least partially address the outlined problems, the prior art has already discussed the use of water-cooled walls (so-called "skulls") in glass melting plants, thereby reducing corrosion of the glass melting tank. However, electrodes are currently inserted through the glass melting tank into the molten glass for conductive heating. So far, it has not been possible to use the electrodes in conjunction with water cooling.

[0005] However, heating solely with fossil fuels using burners above the molten glass is insufficient to compensate for the increased energy losses due to water cooling. Therefore, one possible approach proposed is to introduce energy directly into the molten glass using high-frequency technology instead of electrodes.

[0006] The main problem, however, is that only a small proportion of glasses can actually be heated using high frequencies, as the conductivity of many glasses is not high enough. Furthermore, high-frequency heating leads to an extremely complex design, as well as a departure from the already well-known and proven electrodes. In addition, the high-frequency version with water cooling results in significantly higher energy consumption due to the additional energy losses of the water-cooled glass melting furnace, and thus generally to unacceptable energy costs.

[0007] For example, DE 10 2006 003 535 A1 relates to a method for influencing the temperature of a melt, as well as a method for refining and / or purifying melts, a device for influencing the temperature and / or refining and / or purifying melts, and a product, in particular a glass product, which was melted and / or refined and / or purified and / or produced according to the said method and / or in the said device.

[0008] For example, JP 2001 - 27 692 A relates to a glass melting furnace used for glass solidification of a high-level radioactive waste liquid and for melting the high-level radioactive waste liquid together with a glass raw material, in particular for efficient cooling of a housing.

[0009] For example, EP 0 492 577 A2 concerns phosphate laser glasses.

[0010] For example, US 2007 / 0027016A1 concerns an optical glass with high refractive index and high dispersibility, with good formability in precision pressing and with high transmittance and good internal quality, in which the reduction of transmittance over time is prevented.

[0011] It is therefore an object of the present invention to provide means by which the disadvantages of the prior art can be overcome and which allow a glass melt to be handled safely and reliably and protected against leakage. Furthermore, it is also an object of the present invention to provide means by which the service life of a glass melting furnace can be increased. It is also an object of the present invention to provide glass articles that can be manufactured safely and reliably while maintaining high quality. Description of the invention

[0012] The problem is solved by the invention according to a first aspect in that a safety device for receiving a glass melting tank suitable for preparing, processing and / or holding a glass melt, the safety device comprising: at least one wall, wherein the wall comprises several wall elements and at least partially limits a volume into which the glass melting furnace can be accommodated, wherein the wall elements each have at least one channel system through which at least one fluid can flow; and at least one electrode feedthrough, wherein at least one electrode feedthrough is jointly provided and / or formed by two or more of the wall elements, wherein at least one electrode can be inserted from the outside through the wall element into the volume which is at least partially limited by the wall by means of the electrode feedthrough, wherein at least a first electrical insulation is included by the electrode feedthrough, by means of which the electrode passed through the electrode feedthrough is electrically insulated from the wall element, the channel system and / or the fluid flowing therein, is proposed.

[0013] The invention is based on the surprising finding that the consequences of a glass melting furnace leak can be particularly effectively limited by embedding the furnace in a safety device which itself has a cooled wall. Any escaping molten glass is then collected and contained by the safety device. Furthermore, the water-cooled wall also causes the molten glass to solidify rapidly. This often reliably prevents further leakage of molten glass from the furnace, at least for a certain period of time.

[0014] Once the defective glass melting furnace has been identified, the system can then be safely taken out of service, brought to room temperature, and repaired.

[0015] By equipping the electrode feedthrough with suitable electrical insulation, the inventors have achieved the combination of the well-known, understood, and controllable principle of electrically heating the molten glass using electrodes extending into the glass with the safety advantages of water-cooled walls. This surprisingly ensures that the electrodes do not come into electrical conflict with the wall element or the cooling circuit. Thus, even with metallic walls and / or in the presence of a cooling circuit, current flow from the electrode to the wall or the cooling circuit is effectively prevented.

[0016] Even for glasses that must be melted using electrode heating during production, for example, due to their low electrical conductivity (or the low electrical conductivity of the melt), the advantages of water cooling can be exploited. The content of alkali and alkaline earth ions in the glass material is particularly important for electrical conductivity. Even if these ions fall below a certain percentage (e.g., RO less than 10 wt.% and / or R₂O less than 20 wt.%), melting with the proposed arrangement is possible. In this description, RO stands for alkaline earth metal oxides and R₂O for alkali metal oxides.

[0017] Furthermore, this allows the water cooling to be spatially and technically separated from the glass melting tank, thus overcoming the previously existing problem of electrode feedthrough in a particularly advantageous way.

[0018] Another very advantageous aspect of the present invention is that the proposed solution can be implemented for different geometries of the glass melting furnace to be secured. For example, the geometric structure of the safety device, and in particular the wall, can accordingly be rectangular, round, or polygonal in cross-section. In preferred embodiments, therefore, the wall can be at least partially rectangular, round, or polygonal in cross-section.

[0019] In principle, the wall can have a geometry that differs from that of the glass melting tank. Only the positions of the feedthroughs for the necessary components, such as electrodes, of the wall and the glass melting tank need to be aligned. This allows virtually any existing glass melting tank to be retrofitted with the safety device according to the invention. This is very economical.

[0020] Alternatively or additionally, it may also be provided that the first electrical insulation comprises or consists of a refractory material, preferably quartz and / or mica, and / or has an electrical contact resistance of at least 10 k'Ω. that the first electrical insulation comprises at least one electrical insulation layer, preferably arranged at least partially between the electrode in the installed state and the wall element, and / or that the first electrical insulation, in particular together with the electrode passed through the electrode feedthrough, furthermore constitutes a barrier against molten glass escaping from the glass melting tank, in particular into at least one area between the wall and the glass melting tank.

[0021] The inventors also discovered, quite unexpectedly, that the first electrical insulation, especially when considered together with the electrode present in the operation of the system, can simultaneously serve as leak protection.

[0022] Because the first electrical insulation acts as a barrier to the molten glass, the molten glass contained by the safety device cannot escape from the volume, for example through the hole through which the electrode is inserted. This increases the safety of the safety device.

[0023] Thus, a single feature of the safety device performs a dual function. This is particularly advantageous because it reduces the number of components while simultaneously increasing safety. Furthermore, the design, maintenance, and operation of the safety device are significantly simplified and therefore more efficient.

[0024] Furthermore, it has been shown that, thanks to the electrical insulation in the area around the electrodes, there is no or significantly less corrosion of the wall elements. This also increases the safety and lifespan of the device. With conventional bushings, it was observed that the released electrical energy led to increased corrosion of the wall in the area around the electrodes. At these points, unwanted glass leakage could then occur more easily.

[0025] In other words, the water-cooled wall, in combination with the electrodes integrated into the wall elements and the first layer of electrical insulation, forms a structure that is impermeable to the molten glass. This effectively prevents molten glass from leaking out of the safety device. At the same time, it also prevents electrical short circuits or other unwanted current flow through the wall elements.

[0026] The refractory material fulfills the requirements for electrical insulation and providing a barrier for the glass melt in a particularly good way simultaneously.

[0027] Alternatively or additionally, it can also be provided that the wall comprises 5 or more, preferably 10 or more, even more preferably 12, 16 or 20, wall elements. wherein at least one of the wall elements represents a bottom element of the wall and / or at least one of the wall elements represents a side element of the wall, preferably the wall comprises eight or more side elements and / or four or more bottom elements, and / or wherein there are no gaps passable for the glass melt between the individual wall elements of the wall.

[0028] A wall element within the meaning of the present invention can, for example, be a bottom element or a side element. Transition elements are also conceivable, which connect the bottom area of ​​the wall with the side area of ​​the wall or its parts.

[0029] If the wall elements are arranged in such a way that no gaps remain between individual wall elements, a complete seal against liquid glass is achieved.

[0030] Alternatively or additionally, it may also be provided that the safety device comprises several electrode feedthroughs, in particular at least two, preferably three, four or all, of the wall elements each comprise and / or form at least one electrode feedthrough equipped with a first electrical insulation, and / or that at least one of the electrode feedthroughs is provided and / or formed jointly by two or more, preferably three, four or five, of the wall elements, preferably the side elements and / or bottom elements.

[0031] If there are multiple wall elements with electrode feedthroughs, several electrodes can be inserted into the volume from different directions. This allows for better control of the glass melt.

[0032] For example, one electrode can protrude into the volume from below, for instance through a bottom element, and one or more electrodes can protrude from the side, for instance through one or more side elements.

[0033] Each wall element can also provide only a portion of the electrode feedthrough. This allows, for example, central feedthroughs to be achieved even over large areas without having to use a single, and therefore difficult to handle, wall element. This enables a simple and safe system design.

[0034] Alternatively or additionally, it may also be provided that at least one of the wall elements comprises two, three, four, five, six, seven, eight, nine, ten or more channel systems and / or that the channel system(s) of the individual wall elements is formed at least partially in a thickness range of the respective wall element and / or comprises at least partially formed or formable channels through bores or milling within the respective wall element.

[0035] If a wall element comprises multiple channel systems, different areas of the wall can be cooled differently. For example, a different fluid flow rate can be used depending on the channel system. Or the channel systems can be dimensioned differently.

[0036] If the channel system is integrated within the wall thickness, the cooling circuit can be implemented compactly, as the wall elements already provide all the necessary channels. Drilling and milling can be carried out in the wall elements with particular precision and using standard methods.

[0037] Alternatively or additionally, it may also be provided that the channel system of the individual wall elements has at least one inlet and / or outlet encompassed by the respective wall element, in particular that the channel system is permeable to the respective fluid from the inlet to the outlet.

[0038] The cooling circuit of the individual wall elements can be closed particularly safely and easily via the inlet and outlet, by connecting external peripheral devices, such as pumps and the like, using known methods.

[0039] Water, air, thermal oil or another fluid can preferably be used as the fluid.

[0040] If a wall element has multiple channel systems, it preferably also has multiple inlets and outlets, wherein each channel system of the wall element preferably has one or more of its own inlets and one or more of its own outlets. Preferably, each channel system of a wall element is fluidally isolated from any other channel systems of this wall element, which in particular does not preclude two or more channel systems of this wall element from being fluidally connected to each other across multiple wall elements.

[0041] Alternatively or additionally, it can also be provided that the channel system of the individual wall elements has a flow cross-section of 1 - 11 cm. 2 , especially 2-3 cm 2, has and / or has a length that provides the wall element in question with a contact surface with the molten glass, in particular between 0.1 and 10 m per square meter of area.

[0042] Proper dimensioning of the flow cross-section helps to ensure, on the one hand, a sufficiently high cooling capacity and thus good corrosion resistance of the wall, while on the other hand keeping heat extraction from the glass melt as low as possible.

[0043] By aligning the length of the channel system with the available contact area, a good compromise can be achieved between reducing corrosion and extracting heat from the molten glass (if the glass melting tank is in direct contact with the wall). It also allows for precise adjustment of the cooling capacity in case of unexpected glass leakage.

[0044] Alternatively or additionally, it may also be provided that the channel system of the individual wall elements is dimensioned in such a way that the fluid is heated by a maximum of 40 K, in particular between 5 and 15 K, when flowing through the channel system, in particular from the inlet to the outlet, especially in the case that the entire side surface of the wall element facing the limited volume is in direct or indirect contact with a glass melt with a temperature of at least 800°C.

[0045] By designing the channel system to limit the temperature increase of the fluid, a good compromise can be achieved between reducing corrosion and extracting heat from the molten glass (if the glass melting tank is in direct contact with the wall). It also allows for precise adjustment of the cooling capacity in case of an unexpected glass leak.

[0046] In preferred embodiments, the maximum inlet pressure can be 8 bar or less, preferably a maximum of 6 bar, between 5 and 8 bar, between 4 and 6 bar, or less than 5 bar.

[0047] In preferred embodiments, the outlet may be provided to be free. This means it is not subject to any specific pressure limitation and a virtually free discharge of the fluid is possible.

[0048] Alternatively or additionally, it may also be provided that the channel systems of at least some of the wall elements are fluidically connected or connectable to form a common channel system, so that a common fluid can flow through the channel systems of the wall elements concerned, in particular from a common inlet to a common outlet. wherein preferably the common channel system is dimensioned such that the fluid is heated by a maximum of 40 K, in particular between 5 and 15 K, when flowing through the common channel system, in particular from the common inlet to the common outlet, especially in the case that the complete side surfaces of the wall elements facing the limited volume are in direct or indirect contact with a glass melt at a temperature of 800°C.

[0049] If the individual duct systems are all or partially interconnected, the number of peripheral devices such as pumps and the like is reduced. Furthermore, only a single cooling circuit needs to be monitored, instead of several.

[0050] For example, the outlet of one channel system can be connected to the inlet of the adjacent channel system, and only one inlet (of the first channel system) and one outlet (of the last channel system) can be connected to external devices and / or lines.

[0051] Preferably, it may be provided that only the channel systems of the base elements are fluidly connected or connectable to form a common channel system. Preferably, it may also be provided that only the channel systems of the side elements are fluidly connected or connectable to form a common channel system.

[0052] In preferred embodiments, the maximum inlet pressure can be 8 bar or less, preferably a maximum of 6 bar, between 5 and 8 bar, between 4 and 6 bar, or less than 5 bar. If several channel systems are fluidically interconnected, the inlet pressure is preferably the pressure at the (single) inlet of the interconnected channel system.

[0053] In preferred embodiments, the outlet may be provided to be unobstructed. This means it is not subject to any specific pressure limitation, and a virtually free discharge of the fluid is possible. If several channel systems are fluidically interconnected, the outlet is, in this respect, the (only) outlet of the interconnected channel system.

[0054] Alternatively or additionally, it can also be provided that adjacent wall elements are each electrically insulated from each other by means of at least a second electrical insulation, wherein preferably the second electrical insulation (i) comprises or consists of a refractory material, preferably quartz, at least a layered silicate, such as mica, and / or has an electrical contact resistance of at least 10 k'Ω, and / or (ii) comprises at least one electrical insulating layer, preferably arranged at least partially between the adjacent wall elements, which in particular has a thickness of between 2 and 30 mm, in particular between 5 and 15 mm.

[0055] Electrical insulation of adjacent wall elements leads to increased safety, as any unwanted current flows occurring through the water-cooled components, especially the wall elements, are locally limited or even completely avoided.

[0056] If, in unexpected cases, the first insulation between an electrode and a wall element fails and current flows from the electrode to the wall element, such current flow across multiple wall elements can be reliably prevented. This is particularly effective in preventing current flow between two electrodes located in two different wall elements.

[0057] Furthermore, especially with glasses that have low electrical conductivity, and particularly at low temperatures of the glass or the molten glass, the electrical conductivity through the wall elements can be higher than through the glass material itself, especially the molten glass. The secondary insulation then prevents current flow through the (for example, metallic) wall elements and thus reliably prevents potential short circuits.

[0058] Alternatively or additionally, it may also be provided that the safety device has at least one electrode, at least partially arranged in and / or passing through the electrode feedthrough, wherein the electrode preferably has at least one holder and / or at least one electrode material, in particular comprising platinum, which is preferably supported by the holder.

[0059] The electrode can be used particularly advantageously in the safety device.

[0060] The holder allows for particularly easy installation and removal of the electrode. It also ensures that the electrode or electrode material is held securely.

[0061] Preferably, the bracket is made of or comprises stainless steel. Preferably, the bracket can be multi-walled, in particular with a water channel provided between individual walls. The bracket can thus advantageously be arranged in and / or on the wall.

[0062] For example, the fluid could flow into an inner shell with the flow direction from the outside towards the molten glass. At the point of the holder that extends deepest into the wall, the fluid could alternatively or additionally be deflected and / or returned to the outside to the fluid outlet.

[0063] It may be preferred that at least one, preferably all, electrode feedthroughs each have an electrode. The holder keeps the electrode material in position relative to the wall element and / or the device.

[0064] Preferably the holder is electrically non-conductive, in particular it has an electrical contact resistance of more than 10 k'Ω.

[0065] The expert understands that the electrode can also be used independently, i.e., without a safety device.

[0066] Alternatively or additionally, it may also be provided that (i) the holder has at least one further channel system, wherein preferably (a) a fluid can thus be guided within the holder from an inlet to an outlet of the further channel system, both of which are preferably encompassed by the holder, (b) the further channel system has at least a first section and / or at least a second section and in particular (aa) the two sections are arranged at least partially concentrically to each other, in particular the first section is arranged at least partially within the second section, (bb) the first section and / or the second section each have an annular cross-section in a cross-sectional plane perpendicular to the flow direction of the fluid,and / or (cc) the first section and the second section are fluidly connected to each other via a transition area, and in particular the fluid within the transition area has at least partial direct or indirect contact with the electrode material; and / or (c) the further channel system is fluidly connected to the channel system of the wall element; (ii) the holder has at least one stop element and / or locking element, preferably annular in design, which preferably interacts with the electrode feedthrough and / or the associated wall element; (iii) the electrode has at least one thermocouple, preferably arranged at least partially within the electrode material, and wherein the electrode preferably further has at least one protective element, preferably in the form of a tube,that at least partially surrounds the thermocouple and / or within which the electrical connections of the thermocouple are led to the outside of the electrode; and / or (iv) the electrode has at least one connection element for supplying the electrode, in particular the electrode material, with electrical energy, in particular for applying an electrical voltage and / or an electric current to the electrode material.

[0067] The additional channel system effectively prevents the mounting bracket from overheating. This ensures the safe operation of the safety device. Particularly in the area of ​​the electrode feedthrough, corrosion of the wall material can be reliably reduced or even completely prevented.

[0068] Dividing the duct system into several sections allows for a particularly compact design. Especially when different sections are arranged concentrically, cooling can be achieved even in very limited spaces.

[0069] If the fluid is in contact with the electrode material within the wider channel system, heat dissipation can be particularly efficient. Indirect contact between the fluid and the electrode material could occur, for example, if the electrode material is separated from the fluid by a layer of another material. In other words, if the fluid is in contact with the other material, and the other material is in contact with the electrode material.

[0070] A stop element prevents the electrode from being inserted too far, ensuring reliable operation. A locking element securely and reliably positions the electrode within the electrode feedthrough.

[0071] The thermocouple allows monitoring of the electrode temperature, particularly of the electrode material. In case of overheating, the electrode can be switched off. Of course, instead of a thermocouple, another element can preferably be used that enables at least local temperature measurement of the electrode, especially of the electrode material.

[0072] The protective element protects the thermocouple from damage. Preferably, the protective element has virtually no effect on the thermocouple's temperature measurement.

[0073] It may be preferable for the first and / or second section of the further channel system to run in a spiral shape. This allows for a particularly advantageous cooling effect, also with regard to the mounting.

[0074] Preferably, the bracket has a cylindrical body. Preferably, the further channel system is at least partially and / or in cross-section designed in the form of a planar labyrinth. The position of the surface cooling and the transition to the thermally insulated area can preferably be coordinated.

[0075] The expert understands that the electrode can also be used independently, i.e., without a safety device. This is because the advantages of a fluid-cooled, especially water-cooled, electrode can be very effectively utilized even when isolated and / or in conjunction with other devices.

[0076] Alternatively or additionally, the safety device may also include a control unit designed to monitor the cooling circuits provided by the individual duct systems or the common duct system, based on the supply and return temperatures and / or the respective fluid volume flow rate, and / or designed to detect at least one fault current flowing through at least one wall element.

[0077] It is irrelevant whether there is only one common cooling circuit and / or one or more individual cooling circuits. In all three cases, the control unit can, for example, determine whether the relevant fluid temperatures exceed maximum values. This ensures safe operation.

[0078] For example, for a single cooling circuit under consideration (whether for a single wall element or a common circuit), the difference between the supply and return temperatures can be set to a maximum acceptable value. If this value is exceeded, the control unit can initiate an emergency action, such as triggering an alarm. This allows for the reliable detection of, for example, impermissible heating of the safety device, such as that caused by molten glass escaping from the melting furnace.

[0079] For example, the fluid flow rate for a single cooling circuit (whether for a single wall element or a common circuit) can be set to an acceptable range. If this range is exceeded or fallen below, the control unit can initiate an emergency action, such as triggering an alarm. This allows for the quick and reliable detection of blockages or leaks in the duct system.

[0080] Alternatively or additionally, it may also be provided that the wall elements (i) comprise or consist of at least a metal, in particular aluminium, or at least a metal alloy and / or (ii) have a melting temperature greater than 600°C and / or the fluid comprises water.

[0081] The problem is solved by the invention according to a second aspect in that a glass melting plant comprising at least one safety device according to the first aspect of the invention and at least one glass melting tank for preparing, processing and / or holding a glass melt, wherein the glass melting furnace is incorporated into the volume at least partially limited by the wall of the safety device, wherein the glass melting tank has at least one bore for passing an electrode through the glass melting tank, and wherein the bore is coaxially aligned with respect to at least one electrode passage of the safety device, wherein the glass melting apparatus further comprises at least one electrode which is proposed to protrude from the outside through the electrode feedthrough and the bore into the volume enclosed by the glass melting tank.

[0082] By protecting a glass melting furnace with a safety device according to the first aspect of the invention, all the advantages described with regard to the safety device can be exploited directly during the use of the glass melting plant according to the invention.

[0083] In particular, all conventional glass melting furnaces can be used without problems together with the safety device according to the invention. Only the electrode feedthrough and bore need to be arranged and / or aligned appropriately with each other so that the electrode can be positioned in such a way that it projects into the volume enclosed by the glass melting furnace.

[0084] Alternatively or additionally, it may also be provided that the glass melting tank at least partially comprises or consists of one or more refractory materials, in particular that the material of the glass melting tank is applied or can be applied to the wall by spraying, sputtering, slip or manual application, and preferably that the glass melting tank is formed or can be formed in this way.

[0085] If the glass melting tank is made of or includes refractory or non-corrosive materials, the melting volume of the glass melting tank can be kept constant, as it does not change or changes significantly less over a certain operating period.

[0086] This ensures constant process conditions, enabling the production of consistently high-quality glass melts. Despite potentially higher energy costs, this leads to a more economical process, as it can be operated much more stably and the lifespan of such a system is significantly longer compared to previously used systems.

[0087] By incorporating additional refractory materials within the water-cooled wall structure, energy loss through the water-cooled wall can be significantly reduced.

[0088] In preferred embodiments, additional material, such as refractory or non-corrosive material, can be introduced between the glass melting tank (particularly if it consists of or comprises refractory or non-corrosive material) and the wall. For example, this additional material could be at least partially different from the material of the glass melting tank and / or the wall. The additional material advantageously improves the stability of the entire assembly, and especially of the glass melting tank, even when the geometries of the wall and the glass melting tank differ, thereby increasing overall safety. This allows the water cooling system to be used universally with glass melting tanks of different geometries, such as different cross-sections.In preferred embodiments, the refractory material is applied to the wall, at least in certain areas, by bonding. This allows for a simple implementation, since, in other words, the water-cooled walls are covered with refractory material.

[0089] In addition, the construction with glued-on refractory material, such as quartz plates in particular, leads to significantly lower energy losses than a "naked" water-cooled wall.

[0090] The glass melting furnace can advantageously be formed by applying the material directly to its wall. This allows, for example, the safety device to be provided and installed as a single unit with the glass melting furnace. This is very efficient.

[0091] Alternatively or additionally, it may also be provided that (i) the wall is at least partially spaced away from the glass melting tank and / or (ii) at least a part of the wall is in direct or indirect contact with at least one part of the glass melting tank, in particular a part comprising a refractory material, in particular a thermal paste or an adhesive, such as in particular an inorganic adhesive, is provided between the wall and the glass melting tank and / or a non-destructively separable connection exists between the wall and the glass melting tank.

[0092] The inventors were quite surprised to discover that by having the glass melting tank in direct contact with the wall, corrosion of the glass melting tank could be significantly reduced. This is because the heat from the glass melting tank is cooled away directly, thus counteracting corrosion at the core.

[0093] Since the reduced corrosion simultaneously reduces impurities in the glass melt, the invention makes it possible, on the one hand, to produce even sensitive glasses, such as optical glasses or glasses for bio- or pharmaceutical applications, free of impurities. On the other hand, the invention also allows aggressive glasses to be melted and produced without significantly increasing the wear of the refractory material, such as fused silica (sintered silica), or causing impurities in the glass melt or a reduction in refractive power. Aggressive glasses are characterized, for example, by a high B₂O₃ or P₂O₅ content. Even a B₂O₃ content is considered high. 3- A content of more than 4 wt% or more than 6 wt%. In the case of phosphate-containing glasses, this also prevents the glasses from turning brown due to redox reactions between phosphates and metals (Nb, Ti).

[0094] Particularly in remelting processes with changing glass components and / or changing melting temperatures, corrosion phenomena and the associated consequential problems can be reliably avoided with the invention.

[0095] In addition to classic defects such as bubbles or inclusions, undesirable and intolerable changes in the product properties of the final glass article can also be effectively addressed.

[0096] In any case, the reduced corrosion also prevents the release of SiO2 into the glass melt. This conventionally occurs through corrosion of quartz in the glass melting tank. Therefore, with the present invention, the refractive index of the glass is no longer affected by SiO2, and specified areas of the glass can be reliably guaranteed.

[0097] The inventors also recognized a particular advantage in the fact that the reduced corrosion ensures the melting tank maintains a constant thickness throughout its operating life. This means the volume available for molten glass remains virtually constant. Process settings therefore only need to be defined once at the beginning. The constant and consistently known volume of the glass melting tank is a major advantage in design and process control, as practically no readjustment of the process settings is necessary.

[0098] In summary, the present invention makes it particularly easy to prevent or at least reduce corrosion of the glass melting tank through water cooling. At the same time, the molten glass can still be heated via electrodes extending into the glass, in particular by means of fossil fuel heating and conductive heating. This leads to a longer lifespan for the glass melting tank and a reduction in impurities in the glass melt. Consequently, even highly aggressive and / or impurity-sensitive glasses can be melted more effectively than in conventional tanks.

[0099] Furthermore, there are no restrictions regarding the materials used for the glass melting furnace (or parts thereof). All common materials, such as metals or ceramics, including, for example, refractory materials such as oxide ceramics, e.g., high zirconia fused cast (HZFC) material (melt-cast ZrO2), AZS (melt-cast or ceramic-bonded mixture of Al2O3, ZrO2, SiO2), fused silica (sintered silica glass, quartz), SiO2, Al2O3, ZrO2, and combinations thereof, can be used. In a preferred embodiment, the oxide ceramic contains at least 50 wt.% SiO2, in particular at least 70 wt.% or at least 90 wt.%.

[0100] Refractory materials within the meaning of the present invention are all metallic and ceramic materials with a temperature resistance of at least 600°C and / or for operating temperatures above 600°C.

[0101] In preferred embodiments, it can therefore be provided that the glass melting tank consists at least partially of or comprises at least one ceramic material, preferably a refractory material, such as in particular HZFC, AZS, aluminates, zirconates, silicates, aluminum oxide, zirconium oxide, silicon oxide, quartz, silica or alumina, or combinations thereof.

[0102] The contact and heat transfer between the wall and the glass melting tank can be improved by using thermal paste or adhesive, thereby making the cooling effect more efficient. This results in less corrosion and lower energy consumption.

[0103] In other words, by designing the glass melting tank in such a way that the water-cooled wall elements have a flat, intimate contact with the (ceramic) material, in particular refractory material, and especially by using a suitable thermal paste or adhesive, an optimal heat flow between the (ceramic) material and the water-cooled wall elements is achieved.

[0104] This can significantly reduce the wear and tear on the glass melting furnace.

[0105] By directly integrating the (ceramic) material within the structure of a water-cooled wall, the energy loss through the cooled walls can preferably be significantly reduced.

[0106] Due to the increase in the temperature gradient between the inside and outside of the glass melting plant caused by the water-cooled wall elements, the corrosion of the ceramic material is reduced.

[0107] Preferably, the wall thickness of the glass melting tank can be thinner than in conventional systems. Due to the thinner walls and direct contact with the tank's surface, the water cooling system of the safety enclosure can dissipate heat from the entire thickness range of the melting tank. This prevents corrosion of the melting tank, thus preventing leaks and contamination of the molten glass. And in the worst-case scenario of the melting tank rupturing, the glass solidifies immediately against the water-cooled wall of the safety enclosure.

[0108] Alternatively or additionally, it may also be provided that the material of the glass melting tank has a thickness, preferably varying locally, adapted to the cooling capacity of the cooling circuit(s) of the safety device and / or has at least in some areas an average thickness of between 5 and 150 mm, in particular side parts having an average thickness of 5 to 50 mm and / or bottom parts having an average thickness of 50 to 150 mm.

[0109] The inventors made the remarkable observation that a material layer thickness adapted to the specific requirements of the system achieves an optimum balance between minimal energy loss and maximum dimensional stability. This is especially true when the glass melting furnace has indirect or direct contact with the wall of the safety device.

[0110] By using a suitable thickness, the glass melting tank can be designed to be just as thick as necessary (to provide sufficient stability and resistance to the molten glass) and as thin as possible (to achieve a cooling effect throughout the entire depth range and thus prevent corrosion).

[0111] A permanently dimensionally stable glass melting tank can be achieved by adapting the thickness of the ceramic material to the depth of penetration of the water cooling system in the wall. This is particularly surprising because it typically leads to a significant reduction in the material thickness of the glass melting tank. Contrary to expectations, however, this does not reduce the safety, especially the leakage resistance, of the glass melting tank. Since corrosion of the glass melting tank is simultaneously stopped or significantly reduced, it is sometimes even increased. And even in the unexpected event that the glass melting tank breaks at a certain point, the molten glass escaping from the tank is contained by the water-cooled wall and can solidify there. This ensures extremely effective leakage protection.

[0112] To minimize corrosion of the ceramic material, it is advantageous to achieve a close, surface-covering bond between the water-cooled wall and the ceramic material. This can be achieved, for example, by using a special inorganic adhesive.

[0113] This allows for optimal achievement of both safe operation of the glass melting plant and purity of the glass melt.

[0114] The problem is solved by the invention according to a third aspect by proposing a glass article, at least partially manufactured or manufacturable with a glass melting plant according to the second aspect of the invention.

[0115] Glass articles manufactured / manufacturable with a glass melting plant according to the second aspect of the invention can be produced with higher purity due to the improved corrosion resistance of the glass melting furnace. Furthermore, glass articles with aggressive glass compositions can also be easily produced using this method.

[0116] According to the invention, glass articles that can be produced / produced with a glass melting plant according to the second aspect of the invention are also included, wherein the glass article has less than 300 ppm, preferably less than 100 ppm, (w / w) SiO2 in its glass material, that the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) iron in its glass material, that the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) copper in its glass material, that the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) cobalt in its glass material, that the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) nickel in its glass material, that the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) vanadium in its glass material, that the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) manganese in its glass material.that the glass article contains less than 100 ppm (w / w) zirconium in its glass material, and / or that the glass article contains less than 100 ppm, preferably less than 50 ppm, (w / w) hafnium in its glass material.

[0117] Glass with no or very low SiO2 content is particularly advantageous for various applications because its refractive power is especially precise. Glass without coloring elements such as iron, copper, cobalt, nickel, vanadium, or manganese, or with only small amounts of these elements, is very beneficial for optical lenses.

[0118] When this description states that the glasses are "without" or "free" of a component, or do not contain a certain component, this means that this component may only be present in the glasses as an impurity. This means that it is not added in significant quantities. According to the invention, non-significant quantities are amounts of less than 100 ppm, preferably less than 50 ppm, and most preferably less than 10 ppm (w / w).

[0119] For other colored glasses, glasses without zirconium and hafnium, or with only a small proportion of them, are particularly advantageous.

[0120] Alternatively or additionally, it may also be stipulated that the specific electrical resistance of the glass is a maximum of 10 k'Ωcm, particularly at 1200°C.

[0121] A glass article with low electrical conductivity of the glass material is particularly preferred, as it is a good insulator. Above all, such a glass can be produced particularly advantageously with the device according to the invention, since even glasses with low conductivity can be melted with it.

[0122] The problem is solved by the invention according to a fourth aspect in that a glass article, in particular according to the third aspect of the invention, wherein the glass article has less than 3 ppm, preferably less than 1 ppm, more preferably less than 100 ppb, even more preferably less than 50 ppb, and most preferably less than 15 ppm (w / w) Pt in its glass material; and / or wherein the glass article has less than 10 wt.%, preferably less than 5 wt.%, even more preferably less than 2 wt.% F in its glass material is proposed.

[0123] The inventors recognized that a suitable choice of glass material leads to a particularly high-quality glass product. It was discovered that a low platinum content is precisely what distinguishes a particularly durable glass product, which, above all, exhibits exceptionally high transmission. A low platinum content can even be achieved for aggressive glasses using the solutions described herein. Aggressive glasses are, in particular, glasses with more than 4 wt% or more than 6 wt% B₂O₃, as well as glasses containing P₂O₅. The invention provides, for the first time, glasses of this type with the purity described here. If such aggressive glasses were melted in a conventional furnace with wall elements made of oxide ceramic, the ceramic erosion would be very high, and a large amount of ceramic would enter the melt, thereby contaminating it with, for example, SiO₂, Al₂O₃, and / or ZrO₂.Such glasses are therefore melted in platinum baths, resulting in a significant influx of platinum into the melt.

[0124] In a preferred embodiment, the glass article contains less than 3 ppm, preferably less than 1 ppm, more preferably less than 100 ppb, even more preferably less than 50 ppb, and most preferably less than 15 ppm of platinum in its glass material. Platinum can reduce transmission and should therefore be avoided as much as possible.

[0125] Alternatively or additionally, it may also be provided that the glass article has more than 4 wt.%, preferably more than 8 wt.%, even more preferably more than 15 wt.% B2O3 in its glass material; that the glass article contains between 0 and 10 wt.%, preferably between 0 and 5 wt.%, more preferably between 0 and 3 wt.%, and most preferably 0 wt.% P2O5 in its glass material; that the sum of RO + R'2O in the glass material of the glass article is less than 30 wt.%, preferably less than 20 wt.%, more preferably less than 10 wt.%; that the proportion of RO (R = Mg, Ca, Sr, Ba) in the glass material of the glass article is less than 15 wt.%, preferably less than 10 wt.%, most preferably less than 5 wt.%; and / or that the proportion of R'2O (R' = Li, Na, K, Rb, Cs) in the glass material of the glass article is less than 20 wt.%, preferably less than 10 wt.%, more preferably less than 5 wt.%.

[0126] The sum of RO + R'2O in the glass material of the glass article can be less than 15 wt.%, preferably less than 10 wt.%, even more preferably less than 5 wt.%, or the glass material of the glass article can be free of these oxides.

[0127] In one embodiment, the glass material of the glass article comprises more than 4 wt% B₂O₃, 0 to 10 wt% P₂O₅, and less than 3 ppm platinum, wherein the sum of RO + R'₂O in the glass material of the glass article is less than 15 wt%. The glass material of the glass article may be free of RO and / or R'₂O.

[0128] In one embodiment, the glass material of the glass article comprises more than 4 wt% B₂O₃, 0 to 10 wt% P₂O₅, and less than 3 ppm platinum, wherein the sum of RO + R'₂O in the glass material of the glass article is 5 to 20 wt%, the proportion of RO (R = Mg, Ca, Sr, Ba) in the glass material of the glass article being 0–10 wt% and the proportion of R'₂O (R' = Li, Na, K, Rb, Cs) in the glass material of the glass article being less than 20 wt%. The glass material of the glass article may be free of RO or R'₂O.

[0129] The glass articles according to the invention are particularly well suited as optical glasses or colored glasses. It has been shown that optical glasses and colored glasses exhibit particularly good properties when they have a high boron content and / or are essentially free of phosphates.

[0130] In one embodiment, it is alternatively or additionally provided that the glass article has more than 4.0 wt.%, preferably more than 5.0 wt.%, even more preferably more than 15.0 wt.%, of B2O3 in its glass material.

[0131] In one embodiment, it is alternatively or additionally provided that the glass article contains between 0 and 10 wt.%, preferably between 0 and 5 wt.%, and even more preferably between 0 and 3 wt.% of P₂O₅ in its glass material. Optionally, the glass material is free of P₂O₅.

[0132] It has also been shown that, depending on the electrical conductivity, particularly mediated by conductive (alkali / alkaline earth) ions, especially good glasses for different applications can be obtained. Accordingly, in preferred embodiments, the glass material of the glass article is either non-alkaline or only slightly alkaline (earth-)based. Such glasses were difficult to produce platinum-free in the prior art, as their poor conductivity makes them unsuitable for crucible glass production.

[0133] In one embodiment, it is alternatively or additionally provided that the sum of RO + R₂O in the glass material of the glass article is less than 15.0 wt.%, preferably less than 10.0 wt.%, more preferably less than 5.0 wt.%, more preferably less than 3.0 wt.%, and most preferably less than 1.0 wt.%. In one embodiment, these glasses are essentially free of RO and / or R₂O.

[0134] Glass articles that not only have a high boron content and / or are essentially free of phosphates, but are also free of (earth) alkali, are particularly preferred for optical glasses.

[0135] Two alternative preferred composition ranges for high boron glasses that are essentially free of P₂O₅ and RO are limited by the range boundaries specified in the table below. The glass material of the glass article, particularly for optical glasses, may comprise the following components (in wt.%): Komponenten min. max. min. max. SiO2 3,00 12,00 4,00 10,00 B2O3 4,00 29,00 4,5 28,00 BaO 0 1,00 0 0,4 ZnO 0,00 25,00 0,00 24,00 TiO2 0,00 15,00 0,00 12,00 ZrO2 2,00 10,00 2,50 8,50 La2O3 30,00 60,00 35,00 50,00 Gd2O3 0,00 10,00 0,00 8,00 Y2O3 0,00 10,00 0,00 9,00 Ta2O5 0,00 10,00 0,00 8,00 Nb2O3 0,00 12,00 0,00 10,00 As2O3 0,00 1,00 0,00 0,50 Sb2O3 0,00 1,00 0,00 0,50

[0136] Since it has been shown that, depending on the electrical conductivity, particularly mediated by conductive (alkali / alkaline earth) ions, especially good glasses for different applications can be obtained, the glass material of the glass article is accordingly (alkaline earth) in preferred embodiments.

[0137] In one embodiment, it is alternatively or additionally provided that the sum of RO + R2O in the glass material of the glass article is between 4 and 20 wt.%, preferably between 10 and 18 wt.%, even more preferably between 12 and 15 wt.%.

[0138] In one embodiment, it is alternatively or additionally provided that the proportion of RO (R = Mg, Ca, Sr, Ba) in the glass material of the glass article is less than 15 wt.%, preferably less than 10 wt.%, even more preferably less than 5 wt.%, and most preferably less than 0.1 wt.%. Optionally, the glass is free of RO.

[0139] In one embodiment, it is alternatively or additionally provided that the proportion of R2O (R = Li, Na, K, Rb, Cs) in the glass material of the glass article is between 0 and 20 wt.%, preferably between 5 and 15 wt.% or between 12 and 18 wt.%.

[0140] Glass articles that not only have a high boron content and / or are essentially free of phosphates, but also have a comparatively high proportion of (earth) alkali, are particularly preferred for colored glasses.

[0141] Two alternative preferred composition ranges for glasses with high boron content and low RO content are limited by the range limits specified in the table below. The glass material of the glass article, particularly for colored glasses, may comprise the following components (in wt.%): Komponenten min. max. min. max. SiO2 45,00 70,00 50,00 61,00 B2O3 14,00 24,00 16,00 22,00 Al2O3 0,00 5,00 >0,00 2,50 Na2O 0,00 5,00 >0,00 1,00 K2O 8,00 20,00 10,00 16,50 ZnO 2,00 6,00 3,00 5,00 CoO 0,00 1,00 >0,00 0,50 Fe2O3 0,00 12,00 >0,1 10,0 F2-O 0,00 4,00 >0,50 2,50 Cl2-0 0,00 1,00 >0,1 0,80

[0142] Alternatively or additionally, it may also be provided that the glass article contains between 0 and 12 wt.%, preferably between 0 and 10 wt.%, even more preferably between 0 and 7 wt.% B2O3 in its glass material; that the glass article contains more than 10 wt.%, preferably more than 15 wt.%, even more preferably more than 20 wt.% P2O5 in its glass material; that the glass article contains less than 1 wt.%, preferably less than 0.5 wt.%, even more preferably less than 0.1 wt.%, and most preferably less than 0.01 wt.% SiO2 in its glass material; and / or that the glass article contains less than 8 wt.%, preferably less than 5 wt.% F in its glass material.

[0143] In one embodiment, it is alternatively or additionally provided that the glass article has more than 10 wt.%, preferably more than 15 wt.%, even more preferably more than 20 wt.%, of P2O5 in its glass material.

[0144] In one embodiment, it is alternatively or additionally provided that the glass article contains between 0 and 12 wt.%, preferably between 0 and 10 wt.%, more preferably between 0 and 7 wt.%, of B2O3 in its glass material.

[0145] Optionally, the RO content in the glass is from 15.00 to 60.00 wt.%, in particular at least 18.00 wt.% and / or at most 52.00 wt.%.

[0146] In the preferred first embodiment, it is alternatively or additionally provided that the glass article contains less than 1 wt.%, preferably less than 0.5 wt.%, more preferably less than 0.1 wt.%, and most preferably less than 0.01 wt.%, of SiO2 in its glass material. Optionally, the glass is SiO2-free.

[0147] It has been shown that glasses exhibit good properties when they are made from glasses with a high phosphate content and a larger amount of boron and / or alkali / alkaline earth ions. Preferably, the glasses are free of SiO2 or almost free of it.

[0148] Glass articles that not only have a high boron content, a low SiO2 content, and / or a higher proportion of (earth) alkali, but also a high phosphate content, are particularly preferred. Fluorine-free glass is optional.

[0149] Two alternative preferred composition ranges for glasses with high P₂O₅ content and high B₂O₃ and / or RO content are limited by the range limits specified in the table below. The glass material of the glass article may comprise the following components (in wt.%): Komponenten min. max. min. max. P2O3 10,00 45,00 20,00 36,00 B2O3 0,00 15,00 0,00 10,00 Al2O3 0,00 5,00 0,00 3,00 K2O 0,00 5,00 0,00 3,50 MgO 0,00 6,00 0,00 5,00 CaO 0,00 12,00 0,00 10,00 BaO 15,00 45,00 19,00 40,00 SrO 0,00 5,00 0,00 2,00 ZnO 0,00 5,00 0,00 2,00 TiO2 0,00 10,00 0,00 6,00 Nb2O3 0,00 60,00 >0,20 50,00 As2O3 0,00 1,00 0,00 0,50 Sb2O3 0,00 1,00 0,00 0,50

[0150] Two alternative preferred composition ranges for glasses with high P₂O₅ content and high B₂O₃ and / or R₂O / RO content are limited by the range limits specified in the table below. The glass material of the glass article, particularly for blue glasses, may comprise the following components (in wt.%): Komponenten min. max. min. max. B2O3 0,00 0,50 0,00 0,10 Al2O3 0,00 10,00 1,00 5,00 Na2O 2,00 8,00 3,50 7,00 K2O 3,00 12,00 5,00 10,00 BaO 0,00 6,00 1,50 5,00 SrO 0,00 0,50 0,00 0,10 CaO 5,00 15,00 8,00 12,00 MgO 2,00 9,00 4,50 8,00 As2O3 0,00 1,00 0,00 0,50 Sb2O3 0,00 1,00 0,00 0,50 CuO >0,00 6,00 >0,10 4,50 P2O3 45,00 65,00 50,00 60,00 F 1,00 10,00 2,00 8,50

[0151] Alternatively or additionally, it may also be provided that the glass article contains more than 4 wt.%, preferably more than 8 wt.%, even more preferably more than 15 wt.%, of B₂O₃ in its glass material; that the glass article contains between 0 and 10 wt.%, preferably between 0 and 5 wt.%, even more preferably between 0 and 3 wt.%, and most preferably 0 wt.%, of P₂O₅ in its glass material; that the sum of RO + R'₂O in the glass material of the glass article is 5 to 20 wt.%, preferably 10 to 18 wt.%, even more preferably 12 to 15 wt.%; that the proportion of RO (R = Mg, Ca, Sr, Ba) in the glass material of the glass article is less than 10 wt.%, preferably less than 5 wt.%, most preferably 0 wt.%; and / or that the proportion of R'2O (R' = Li, Na, K, Rb, Cs) in the glass material of the glass article is less than 20 wt%, preferably 5 to 18 wt%, more preferably 12 to 15 wt%. Brief description of the characters

[0152] Further features and advantages of the invention will become apparent from the following description, in which preferred embodiments of the invention are explained with reference to schematic drawings.

[0153] This shows: Fig. 1 a safety device according to the invention in accordance with the first aspect of the invention in a perspective view; Fig. 2a a first wall element of the safety device made of Fig. 1 in a first cross-sectional view; Fig. 2b the first wall element in a second cross-sectional view; Fig. 3a a second wall element of the safety device made of Fig. 1 in a first cross-sectional view; Fig. 3b the second wall element in a second cross-sectional view; Fig. 4 a third wall element of the safety device made of Fig. 1 in a cross-sectional view; Fig. 5 a first glass melting furnace of a glass melting plant according to the second aspect of the invention in a cross-sectional view; Fig. 6 a second glass melting furnace of a glass melting plant according to the second aspect of the invention in a cross-sectional view; and Fig. 7 A cross-sectional view of an electrode. Examples

[0154] Fig. Figure 1 shows a safety device 1 according to the invention in a perspective view, in accordance with the first aspect of the invention.

[0155] The safety device 1 can be used to hold a glass melting tank suitable for preparing, processing and / or holding molten glass.

[0156] The safety device 1 comprises a wall 3. The wall 3 comprises several wall elements 5a, 5b, 5c and at least partially defines a volume 7 into which the glass melting tank can be received.

[0157] In fact, wall 3 comprises eight wall elements 5a, 5b in the form of side elements and four in Fig. 1. Only partially visible wall elements 5c in the form of base elements. There are no gaps passable for the glass melt between the individual wall elements 5a, 5b, 5c of the wall 3.

[0158] The wall elements each have at least one channel system through which at least one fluid can flow. The channel system of the individual wall elements has an inlet 9a and an outlet 9b encompassed by the respective wall element. While the channel systems in Fig. While not visible in 1, some of the inlets and outlets 9a, 9b can be seen there. The channel systems are described with reference to the Fig. 2a, Fig. 2b, Fig. 3a, Fig. 3b and Fig. 4 described in detail below.

[0159] It was in Fig. 1. No specific distinction is made between an inlet and an outlet. Depending on the flow direction of the fluid in the channel system and its interconnection, any opening can be used as an inlet or an outlet. An inlet is, for example, an opening through which the fluid flows into the channel system, and an outlet is, for example, an opening through which the fluid flows out of the channel system.

[0160] Wall 3 can therefore also be accurately described as a water-cooled wall. This is because the channel system allows a fluid to flow through wall 3, thus transporting heat away from the wall. This makes the wall suitable for use, for example, in cooling a glass melting furnace and / or molten glass.

[0161] The safety device 1 also includes four electrode feedthroughs 11.

[0162] Another opening is in Fig. 1 not visible. This further opening can be designed similarly to the electrode feedthroughs 11. A precious metal channel system can be flanged there to transport the glass or the molten glass for hot forming.

[0163] The four in Fig. The electrode feedthroughs 11 shown in Figure 1 are each provided and formed by one of the wall elements 5a.

[0164] Each electrode (not shown) can be connected via the electrode feedthroughs 11. Fig. 1) can be passed from the outside through the respective wall element 5a into the volume 7, which is at least partially bounded by the wall 3. An exemplary electrode, which in a preferred embodiment may also be provided by the safety device itself, will be described later with reference to Fig. 7 explained.

[0165] Each of the electrode feedthroughs 11 includes a first electrical insulation 13, by means of which the electrode passed through the respective electrode feedthrough 11 is electrically insulated from the respective wall element 5a, the channel system and / or the fluid flowing therein.

[0166] The first electrical insulation 13 comprises an intermediate layer made of an electrically insulating refractory material arranged between the electrode in the installed state and the wall element 5a.

[0167] Adjacent wall elements 5a, 5b, 5c are each connected by means of at least one (in Fig. 1 (not shown) second electrical insulation from each other, wherein the second electrical insulation comprises an electrical insulation layer arranged between the adjacent wall elements 5a, 5b, 5c.

[0168] Fig. 2a shows one of the wall elements 5a of the safety device Fig. 1 in a first cross-sectional view. This is therefore a side element with an electrode feedthrough 11. Here the channel system 15a of the wall element 5a with an inlet 9a and outlet 9b can be seen.

[0169] Fig. 2b shows the wall element 5a of the Fig. 2a in a second cross-sectional view, which runs along the in Fig. 2a, the dashed line shown runs perpendicularly to the drawing plane of the Fig. 2a is listed.

[0170] Fig. 3a shows one of the wall elements 5b of the safety device. Fig. 1 in a first cross-sectional view. This is therefore a side element without an electrode feedthrough. Here, the channel system 15b of the wall element 5b with an inlet 9a and outlet 9b can be seen.

[0171] Fig. Figure 3b shows the wall element 5b of the Fig. 3a in a second cross-sectional view, perpendicular to the drawing plane of the Fig. 3a is listed.

[0172] The wall elements 5a and 5b each have only one channel system 15a and 15b respectively.

[0173] Fig. Figure 4 shows one of the wall elements 5c of the safety device. Fig. 1 in a first cross-sectional view. This is therefore a floor element.

[0174] In the base of wall 3, a further opening 12, for example in the form of a wall penetration, is provided. This opening can serve as a discharge opening for the molten glass from the glass melting tank. This opening can thus be used to drain the glass from the safety device 1.

[0175] The opening 12 is only partially separated from the wall element 5c of the Fig. 4 provided or formed. In fact, this opening 12 is provided or formed jointly by four of the wall elements 5c. That is to say, in other words, the entire opening 12 is provided or formed by four wall elements 5c.

[0176] Instead of the opening 12, other embodiments could also use an electrode feedthrough, as described above in relation to Fig. As described in section 1, the electrode feedthrough should be provided in the base area of ​​wall 3. Then, accordingly, the four wall elements 5c could jointly provide or form the electrode feedthrough.

[0177] By means of such an electrode feedthrough, an electrode could be passed from the outside through the wall element 5c into the volume 7, which is at least partially limited by the wall 3.

[0178] Such an electrode feedthrough could also include initial electrical insulation, with reference to the corresponding explanations regarding electrode feedthroughs 11 above, as it could then be constructed in a completely analogous manner.

[0179] The wall elements 5c, as shown in Fig. Figure 4 shows a channel system 15c with an inlet 9a and an outlet 9b. The assignment of one opening as inlet 9a and the other as outlet 9b is arbitrary, and the assignment could equally be reversed. This is because which opening functions as outlet and which as inlet depends on the flow direction of the fluid, and this can ultimately be determined by the external connection with peripheral devices, such as pumps. It is therefore in Fig. 4 exactly that one channel system 15c comprises the wall element 5c.

[0180] The channel systems 15a, 15b, 15c of the individual wall elements 5a, 5b, 5c are each formed in a thickness range of the respective wall element 5a, 5b, 5c and comprise, in particular, channels formed or formable by drilling or milling within the respective wall element 5a, 5b, 5c.

[0181] Fig. Figure 5 shows a first glass melting tank 17 of a glass melting system according to the second aspect of the invention in a cross-sectional view. The glass melting tank 17 is suitable for preparing, processing and / or holding a molten glass.

[0182] The glass melting tank 17 can be accommodated within the volume at least partially limited by the wall of a safety device, such as safety device 1, of the glass melting plant. The glass melting tank 17 has five bores 19, of which in Fig. Only four of them are recognizable. Three of them are in Fig. The 5 depicted boreholes 19 are for carrying out the (in Fig. 5 electrodes (not shown) through the glass melting tank. The bore in the bottom of the glass melting tank 17 serves as the outlet for the molten glass.

[0183] The wall of the safety device can be spaced apart from the glass melting furnace 17.

[0184] The openings 19 of the glass melting tank 17 should preferably be aligned concentrically with the electrode and wall penetrations 11, 12 of the safety device when the glass melting tank 17 is received by the safety device.

[0185] Fig. Figure 6 shows a second glass melting tank 21 of a glass melting system according to the second aspect of the invention in a cross-sectional view. The glass melting tank 21 is suitable for preparing, processing and / or holding a molten glass.

[0186] The glass melting tank 21 can be accommodated within the volume at least partially limited by the wall of a safety device, such as safety device 1, of the glass melting plant. The glass melting tank 21 has five bores 23, of which in Fig. Only four of them are recognizable. Three of them are in Fig. The 6 depicted boreholes 23 are for carrying out the (in Fig. 6 electrodes (not shown) pass through the glass melting tank. The bore in the bottom of the glass melting tank 17 serves as the outlet for the molten glass.

[0187] The openings 19 of the glass melting tank 17 should preferably be aligned concentrically with the electrode and wall penetrations 11, 12 of the safety device when the glass melting tank 17 is received by the safety device.

[0188] The wall of the safety device can be in direct contact with the glass melting tank 21. Due to this direct contact, the thickness of the glass melting tank 21 can be increased compared to that specified in relation to Fig. The cooling capacity of the safety device is reduced in the glass melting furnace 17 discussed in section 5, so that the cooling capacity of the safety device acts on the entire material of the glass melting furnace 21.

[0189] Fig. Figure 7 shows a cross-sectional view of an electrode 25, as it may be guided through the individual electrode feedthroughs 11.

[0190] The electrode 25 has a holder 27 and an electrode material 29, which is supported by the holder 27. The electrode material 29 is platinum. The holder 27, in turn, has a channel system 31 through which a fluid can be guided from an inlet 33 to an outlet 35. The channel system 31 has a first section 37 and a second section 39. The two sections 37 and 39 are arranged concentrically to each other. The first section 37 is located within the second section 39. Both sections have an annular cross-section in a cross-sectional plane perpendicular to the flow direction. The first section 37 is connected to the inlet, and the second section 39 is connected to the outlet 35. The arrows within sections 37 and 39, as well as at the inlet and outlet 33 and 35, indicate the flow direction of the fluid. A reverse flow direction would be possible in principle and is determined by the external circuitry.

[0191] The fluid flowing in the channel system 31 cools the holder 27 and the electrode material 29. In a transition region 41, the fluid passes from the first section 37 into the second section 39. In this transition region, the flowing fluid has direct contact with the electrode material 29 and can thus cool the electrode material in a targeted manner by dissipating heat from it. The holder 27, within which the channel system 31 extends, is also cooled in the same way.

[0192] The holder 27 has a ring-shaped stop element 43. This allows the electrode to be securely guided into one of the electrode feedthroughs 11.

[0193] The electrode 25 also has a connection element 45, via which the electrode 25, in particular the electrode material 29, can be supplied with current and voltage.

[0194] The electrode 25 further comprises a thermocouple 47 arranged within the electrode material 29. The thermocouple 47 is surrounded by a protective element in the form of a protective tube 49. The protective tube 49, which runs along the central axis of the electrode 25, allows the electrical terminals of the thermocouple 47 to be routed from the electrode material 29 to the outside. There, the voltage that can be measured at the electrical terminals can be converted into a temperature that exists in the region of the thermocouple 47, and thus in the region of the electrode material 29.

[0195] The channel system 31 of the holder 27 can, for example, be connected to the channel system of the wall, thus enabling a common channel system. This allows the entire fluid flow for cooling both the wall and the electrode 27 to be routed, for example, from a single inlet to a single outlet. Glass compositions

[0196] Exemplary glass compositions of glasses according to the invention are shown below.

[0197] The following table shows exemplary glass compositions of glasses that, due to their absence of RO and R₂O or their only minimal RO and R₂O content, cannot be melted in crucibles and can be produced in high purity for the first time with the present invention. All of these glasses were platinum-free. Komponenten B1 B2 B3 B4 B5 SiO2 6,50 5,41 9,10 4,65 5,30 B2O3 5,10 19,61 6,66 24,90 27,85 BaO 0,30 ZnO 23,51 21,90 3,25 TiO2 10,50 4,21 5,03 0,35 ZrO2 6,40 3,02 7,86 3,60 7,55 La2O3 48,00 36,77 49,00 38,60 46,70 Gd2O3 7,60 7,42 Y2O3 0,50 0,50 8,25 Ta2O3 6,00 5,21 Nb2O3 9,50 7,90 9,11 6,35 As2O3 0,40 Sb2O3 0,10 0,1 0,10 0,10

[0198] The following table shows examples of glass compositions of glasses that, due to their relatively high boron content, are classified as aggressive glasses. All of these glasses were platinum-free. Komponenten B6 B7 B8 B9 B10 B11 B12 B13 SiO2 53,46 56,3 57,12 57,72 55,82 54,99 58,21 59,02 B2O3 16,79 17,68 17,94 18,13 17,53 17,27 18,28 20,97 Al2O3 1,33 1,4 1,42 1,43 1,39 1,37 1,44 1,47 Na2O 0,47 0,49 0,5 0,51 0,49 0,48 0,51 0,52 K2O 13,29 14,0 14,2 14,35 13,87 13,67 14,47 11,75 ZnO 3,54 3,72 3,78 3,82 3,69 3,64 3,85 3,9 CoO 0,3840 0,0660 0,0440 0,0230 0,0940 0,1700 0,0096 0,0044 Fe2O3 9,1 4,61 3,25 2,25 5,39 6,72 1,44 0,45 F2-O 1,23 1,29 1,31 1,33 1,28 1,26 1,34 1,36 Cl2-O 0,42 0,44 0,44 0,45 0,43 0,43 0,45 0,46

[0199] The notation "F2-O" or "Cl2-O," commonly used by experts, indicates how much F2 or Cl2 replaces one O. The following table shows exemplary glass compositions of glasses that, due to their relatively high phosphorus content, are classified as aggressive glasses. All of these glasses were platinum-free. Komponenten B14 B15 P2O5 34,68 22,75 B2O3 9,30 Al2O3 2,50 K2O 2,9 MgO 4,30 CaO 8,15 BaO 38,29 20,75 SrO 1,30 ZnO 0,98 0,50 TiO2 4,76 Nb2O3 0,45 48,04 As2O3 0,01 Sb2O3 0,05

[0200] The following table shows examples of glass compositions of glasses that, due to their relatively high phosphorus content, are classified as aggressive glasses. All of these glasses were platinum-free. Komponenten B16 B17 B18 B19 B20 B2O3 0,05 0,05 0,05 Al2O3 3,10 3,13 3,15 3,03 2,93 Na2O 5,35 5,77 5,44 4,92 4,92 K2O 7,89 7,89 7,95 7,45 7,65 BaO 3,19 3,18 3,23 2,97 2,97 SrO 0,012 0,028 0,012 CaO 10,67 10,52 10,73 11,75 10,548 MgO 6,60 6,60 6,72 6,5 6,5 As2O3 0,026 0,025 0,026 Sb2O3 0,012 0,011 0,012 CuO 3,47 3,51 2,83 0,38 3,05 P2O3 55,59 56,35 56,40 51,94 51,94 F 4,052 2,94 3,46 7,16 7,8

[0201] The features disclosed in the preceding description, in the claims and in the drawings can be essential to the invention in its various embodiments, both individually and in any combination. Reference symbol list 1 safety device 3 walls 5a, 5b, 5c wall element 7 volumes 9a Entrance 9b Exit 11 Electrode feedthrough 12 Wall penetration 13 Electrical Insulation 15a, 15b, 15c Canal system 17 Glass melting furnace 19 bore 21 Glass melting furnace 23 bore 25 electrode 27 bracket 29 Electrode material 31 canal system 33 Admission 35 Outlet Section 37 Section 39 41 Transition area 43 Stop element 45 Connection element 47 Thermocouple 49 Protective tube

Claims

[1] Safety device for receiving a glass melting tank suitable for preparing, processing and / or holding molten glass, the safety device comprising: at least one wall, wherein the wall comprises several wall elements and at least partially limits a volume into which the glass melting furnace can be accommodated, wherein the wall elements each have at least one channel system through which at least one fluid can flow; and at least one electrode feedthrough, wherein at least one electrode feedthrough is jointly provided and / or formed by two or more of the wall elements, wherein at least one electrode can be inserted from the outside through the wall element into the volume which is at least partially limited by the wall by means of the electrode feedthrough, wherein the electrode feedthrough includes at least a first electrical insulation by means of which the electrode passed through the electrode feedthrough is electrically insulated from the wall element, the channel system and / or the fluid flowing therein. [2] Safety device according to claim 1, wherein the first electrical insulation material comprises or consists of a refractory material, preferably quartz and / or mica, and / or has an electrical contact resistance of at least 10 k'Ω, wherein the first electrical insulation comprises at least one electrical insulation layer, preferably arranged at least in certain areas between the electrode in the installed state and the wall element, and / or wherein the first electrical insulation, in particular together with the electrode passed through the electrode feedthrough, furthermore constitutes a barrier against molten glass escaping from the glass melting tank, in particular into at least one area between the wall and the glass melting tank. [3] Safety device according to one of the preceding claims, wherein the wall comprises 5 or more, preferably 10 or more, more preferably 12, 16 or 20, wall elements, wherein at least one of the wall elements represents a bottom element of the wall and / or at least one of the wall elements represents a side element of the wall, preferably the wall comprises eight or more side elements and / or four or more bottom elements, and / or where there are no gaps between the individual wall elements of the wall that are passable for the glass melt. [4] Safety device according to one of the preceding claims, wherein the safety device comprises several electrode feedthroughs, in particular at least two, preferably three, four or all, of which each wall element at least partially comprise and / or form an electrode feedthrough equipped with a first electrical insulation, wherein the at least one electrode feedthrough, which is jointly provided and / or formed by two or more of the wall elements, is jointly provided and / or formed by, preferably three, four or five, wall elements of the side elements and / or bottom elements. and / or wherein the at least one electrode feedthrough, which is jointly provided and / or formed by two or more of the wall elements, is jointly provided and / or formed by three, four or five of the wall elements, preferably the side elements and / or bottom elements. [5] Safety device according to any of the preceding claims, wherein at least one of the wall elements comprises two, three, four, five, six, seven, eight, nine, ten or more channel systems, and / or wherein the channel system(s) of the individual wall elements is formed at least partially in a thickness range of the respective wall element and / or comprises at least partially formed or formable channels through bores or milling within the respective wall element. [6] Safety device according to one of the preceding claims, wherein the channel system of the individual wall elements has at least one inlet and / or outlet encompassed by the respective wall element, in particular the channel system is permeable to the respective fluid from the inlet to the outlet. [7] Safety device according to one of the preceding claims, wherein the channel system of the individual wall elements has a flow cross-section of 1 - 11 cm 2 , especially 2-3 cm 2 , has and / or has a length that provides the wall element in question with a contact surface with the molten glass, in particular between 0.1 and 10 m per square meter of area. [8] Safety device according to one of the preceding claims, wherein the channel system of the individual wall elements is dimensioned such that the fluid is heated by a maximum of 40 K, in particular between 5 and 15 K, when flowing through the channel system, in particular from the inlet to the outlet, especially in the case that the entire side surface of the wall element facing the limited volume is in direct or indirect contact with a glass melt at a temperature of at least 800°C. [9] Safety device according to one of the preceding claims, wherein the channel systems of at least some of the wall elements are fluidly connected or connectable to form a common channel system, so that a common fluid can flow through the channel systems of the wall elements concerned, in particular from a common inlet to a common outlet, wherein preferably the common channel system is dimensioned such that the fluid is heated by a maximum of 40 K, in particular between 5 and 15 K, when flowing through the common channel system, in particular from the common inlet to the common outlet, especially in the case that the complete side surfaces of the wall elements facing the limited volume are in direct or indirect contact with a glass melt at a temperature of 800°C. [10] Safety device according to any of the preceding claims, wherein adjacent wall elements are each electrically insulated from each other by means of at least a second electrical insulation, wherein preferably the second electrical insulation (i) comprises or consists of a refractory material, preferably quartz, at least a layered silicate, such as mica and / or has an electrical contact resistance of at least 10 k'Ω, and / or (ii) comprises at least one electrical insulating layer, preferably arranged at least in certain areas between the adjacent wall elements, which in particular has a thickness of between 2 and 30 mm, in particular between 5 and 15 mm. [11] Safety device according to one of the preceding claims, wherein the safety device has at least one electrode, at least partially arranged in and / or passing through the electrode feedthrough, wherein the electrode preferably has at least one holder and / or at least one electrode material, in particular comprising platinum, which is preferably supported by the holder. [12] Safety device according to claim 11, wherein (i) the support has at least one further channel system, preferably (a) thus a fluid can be guided within the holder from an inlet to an outlet of the further channel system, both of which are preferably enclosed by the holder, (b) the further canal system has at least a first section and / or at least a second section and in particular (aa) the two sections are arranged concentrically to each other at least in certain areas, in particular the first section is arranged at least in certain areas within the second section, (bb) the first section and / or the second section each have an annular cross-section in a cross-sectional plane perpendicular to the direction of fluid flow, and / or (cc) the first section and the second section are fluidly connected to each other via a transition region and, in particular, the fluid within the transition region has direct or indirect contact with the electrode material at least in some areas; and / or (c) the further channel system is fluidly connected to the channel system of the wall element; (ii) the holder has at least one stop element and / or locking element, in particular one of an annular design, which preferably interacts with the electrode feedthrough and / or the associated wall element; (iii) the electrode comprises at least one thermocouple, which is preferably arranged at least partially within the electrode material, and wherein the electrode preferably further comprises at least one protective element, in particular in the form of a tube, which at least partially surrounds the thermocouple and / or within which the electrical terminals of the thermocouple are led to the outside of the electrode; and / or (iv) the electrode has at least one connection element for supplying the electrode, in particular the electrode material, with electrical energy, in particular for applying an electrical voltage and / or an electric current to the electrode material. [13] Safety device according to one of the preceding claims, wherein the safety device comprises a control unit which is configured to monitor the cooling circuits provided by the individual duct systems or the common duct system on the basis of the supply and return temperatures and / or on the basis of the respective fluid volume flow, and / or which is configured to detect at least one fault current flowing through at least one wall element. [14] Safety device according to one of the preceding claims, wherein the wall elements (i) comprise or consist of at least a metal, in particular aluminium, or at least a metal alloy and / or (ii) have a melting temperature greater than 600°C and / or the fluid comprises water. [15] Glass melting plant comprising at least one safety device according to one of claims 1 to 14 and at least one glass melting tank for preparing, processing and / or holding a glass melt, wherein the glass melting furnace is incorporated into the volume at least partially limited by the wall of the safety device, wherein the glass melting tank has at least one bore for passing an electrode through the glass melting tank, and wherein the bore is coaxially aligned with respect to at least one electrode passage of the safety device, wherein the glass melting apparatus further comprises at least one electrode which protrudes from the outside through the electrode feedthrough and the bore into the volume enclosed by the glass melting tank. [16] Glass melting plant according to claim 15, wherein the glass melting furnace at least partially comprises or consists of one or more refractory materials, in particular the material of the glass melting tank is applied or can be applied to the wall by spraying, sputtering, slip or manual application, and preferably the glass melting tank is formed or can be formed by this. [17] Glass melting apparatus according to claim 15 or 16, wherein (i) the wall is at least partially spaced apart from the glass melting tank and / or (ii) at least a part of the wall is in direct or indirect contact with at least one part of the glass melting tank, in particular comprising a refractory material, in particular a thermal paste or an adhesive, such as in particular an inorganic adhesive, is provided between the wall and the glass melting tank and / or a non-destructively separable connection exists between the wall and the glass melting tank. [18] Glass melting plant according to one of claims 15 to 17, wherein the material of the glass melting tank has a thickness, preferably varying locally, adapted to the cooling capacity of the cooling circuit(s) of the safety device and / or has at least in certain areas an average thickness of between 5 and 150 mm, in particular side parts having an average thickness of 5 to 50 mm and / or bottom parts having an average thickness of 50 to 150 mm. [19] Glass articles, at least partially manufactured or manufacturable using a glass melting plant according to any one of claims 15 to 18, wherein the glass article has less than 300 ppm, preferably less than 100 ppm, (w / w) SiO2 in its glass material, wherein the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) iron in its glass material, wherein the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) copper in its glass material, wherein the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) cobalt in its glass material, wherein the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) nickel in its glass material, wherein the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) vanadium in its glass material, wherein the glass article has less than 20 ppm, preferably less than 5 ppm, (w / w) manganese in its glass materialwherein the glass article contains less than 100 ppm (w / w) zirconium in its glass material, and / or wherein the glass article contains less than 100 ppm, preferably less than 50 ppm, (w / w) hafnium in its glass material. [20] Glass articles according to claim 19, wherein the specific electrical resistance of the glass is a maximum of 10 k'Ωcm, particularly at 1200°C.

Images