Method for repairing glass furnace

Abstract

The invention relates to a method for thermally repairing an area (301, 302, 303) to be repaired in a glass furnace (10), said area to be repaired being at a temperature above 300 DEG C, said method comprising the following steps: a) installing an internal template (32i) in a position of use in order to create a mold around said area to be repaired; b) filling the mould with a repair product (41), at least a portion of the inner template being made of a ceramic matrix composite (CMC).

Description

Technical Field

[0001] The invention relates to a method for repairing a glass melting furnace. The invention also relates to a nozzle that can be used to carry out the method. Background Art

[0002] Figure 1 Schematically shown is a half cross section of a glass melting furnace 10. The tank 12, the metal structure 14 and the superstructure 16 can be distinguished in particular.

[0003] The tank 12 for containing molten glass has vertical side walls 22 and a floor 24. The side walls 22 are generally formed by side tank blocks extending over the entire height of the tank to an upper edge 25. The floor of the tank defines a substantially horizontal bottom of the tank, while the substantially vertical side walls surround the bottom.

[0004] The assembly consisting of gap bricks (if present), walls and crown is often referred to as the "superstructure" of the glass melting furnace. The superstructure 16 is used to close the furnace by covering the tank. It does not come into contact with the molten glass. It usually includes at its base an intermediate layer 18, a side wall 26, and a crown 28, the upper structure 16 resting on the metal structure through the intermediate layer 18, and the side wall 26 resting on the intermediate layer. In a gas furnace, the burner, not shown, is arranged in the side wall 26. The intermediate layer 18 includes gap bricks 20, preferably consisting of gap bricks 20.

[0005] The "interior" of the furnace is thus defined by the interior surface 29 which is defined by the outer shell formed by the trough and superstructure.

[0006] Molten glass, steam and condensate are very corrosive. Refractory parts will be severely corroded.

[0007] The refractory components used are usually in the form of blocks or plates, either melted and cast or obtained by sintering. Their selection depends on their placement in order to withstand local stresses and give a satisfactory service life of the furnace. The guiding principle for the selection is also that no failures should occur that would render the glass unusable; this would reduce production yields.

[0008] In order to extend the service life of the furnace, glass manufacturers are advised to repair it. Repair consists in filling the empty spaces created by the erosion of the furnace with repair materials, that is, fixing the repair materials in the area originally occupied by the refractory material that disappeared due to the erosion. This area is called the "area to be repaired".

[0009] like Figure 2As shown, the area to be repaired 30 may be "depressed", that is, in the form of a cavity 301, for example on a bottom plate. It may also be "protruding", that is, it is an area 302 in the continuation of an initially protruding block (e.g., a gap brick). The area to be repaired may also pass through the outer shell of the furnace, so that the interior and exterior fluids of the furnace are in communication. Such a through-area to be repaired may in particular lead to leakage of molten glass in the tank. These leaks are dangerous and may cause the furnace to shut down. The area to be repaired 303 is an example of a through-area to be repaired.

[0010] The area to be repaired is thus an empty (without refractory material) space which is partly bounded by one or more refractory components of the furnace and partly by Figure 2 The virtual envelope shown in dashed lines defines the virtual envelope extending along the surface of one or more refractory components prior to erosion of the refractory components.

[0011] To repair a furnace, as shown in EP 0 739 861, a formwork installation is usually carried out to mark the virtual envelope and to make a mould with one or more refractory parts capable of containing the repair product before it hardens. Formwork elements, for example in the form of flat or non-flat plates, are usually held in their position of use defining the mould by means of attachments.

[0012] The template is partially on the inside of the furnace where the corrosion occurs. The template can also be partially on the outside of the furnace to prevent repair material from escaping the furnace when the corrosion causes a channel through the outer shell of the furnace. The outer part of the template is usually coated. For clarity, the parts of the template inside and outside the furnace are called "inner template" and "outer template", respectively.

[0013] "Hot" repairs are repairs carried out at temperatures generally above 300° C. Therefore, hot repairs require only a limited temperature reduction (called "cooling"), or even no temperature reduction, which greatly limits the time the furnace is not in use. However, the introduction of formwork elements into the furnace can lead to their degradation under the effect of thermal shock.

[0014] Furthermore, the interior of the furnace is not very accessible, which makes it difficult to make internal formwork for certain areas to be repaired. In particular, the introduction of internal formwork elements may require the creation of channels in the outer shell of the furnace. Furthermore, during hot repair, no operator can enter the furnace. Therefore, sometimes the internal formwork must be installed at a certain distance from the area to be repaired. Therefore, the volume and weight of the internal formwork elements can significantly delay the production of the formwork.

[0015] These limitations also make it very difficult to create internal formwork with complex shapes, especially when the area to be repaired protrudes into the furnace.

[0016] The mold is then usually filled with the repair product by means of a pump. The repair product experiences a sudden increase in temperature when entering the mold, which leads in particular to a reduction in flowability. As a result, it is difficult to fill the mold evenly.

[0017] Traditionally, the inner formwork is made of metal and is cooled by water circulation. After the repair product has hardened, the inner formwork must therefore be removed because metal can produce bubbles when in contact with the molten glass.

[0018] After the repair product has hardened, the formwork is removed to make room for the rebuilt refractory components. However, in general, the metal formwork is so complex that it is impossible to reconstruct the original shape. Subsequently, in an operation called "heating", the temperature can be increased to resume operation of the furnace.

[0019] EP 0 739 861 B1 describes an example of a method for repairing a glass melting furnace, in particular a tank.

[0020] There are also products for repairing metal smelting furnaces. However, the mechanical stresses in this application are very different from those encountered in glass furnaces. In particular, the corrosion conditions of molten glass or molten metal are very different. Finally, some impurities that can be tolerated in metal smelting furnaces are unacceptable in glassmaking. In particular, the refractory materials used in glass furnaces must not lead to the release of stones due to chipping or the generation of bubbles. Therefore, a priori repair products for metal smelting furnaces cannot be used in glass furnaces, especially in areas that come into contact with molten glass.

[0021] There remains a need for solutions for repairing glass furnaces which address the above-mentioned problems and in particular allow the furnace to be quickly put back into production without reducing the quality of the produced glass.

[0022] The present invention is directed to at least partially satisfying this need. Summary of the invention

[0023] According to a first main aspect, the invention proposes a method for thermally repairing a region in a glass melting furnace (referred to as the "region to be repaired") at a temperature above 300°C, said method comprising the following steps:

[0024] a) Installing internal formwork at the point of use to create a mould around the area to be repaired;

[0025] b) filling the mould with the repair product, preferably by casting,

[0026] At least a portion of the inner formwork is made of ceramic, preferably in the form of a ceramic matrix composite (CMC).

[0027] As will be seen in more detail in the remainder of the specification, the inventors have particularly discovered that ceramics, particularly in the form of CMCs, do not materially change the quality of the glass produced when in contact with molten glass or the corrosive vapors present in a furnace, thereby eliminating the need to remove the internal formwork after repair is complete.

[0028] Furthermore, ceramics, particularly in the form of CMCs:

[0029] - Lightweight, which makes it easier to handle,

[0030] -Can be easily formed into complex geometries, allowing precise adaptation to the configuration of the area to be repaired.

[0031] Furthermore, CMC is able to withstand thermal shock well, which allows thermal repair without degradation of the formwork elements when they are introduced into the furnace.

[0032] The invention thus allows a particularly rapid return of the furnace to production without the repairs having an adverse effect on the quality of the glass, in particular on the number of defects in the glass.

[0033] The method according to the invention may also include one or more of the following optional and preferred features:

[0034] - The area to be repaired is located in the tank and / or superstructure;

[0035] - sintering the ceramic, preferably in the form of a CMC;

[0036] - the ceramic, preferably in the form of a CMC, consists of more than 90% by weight of oxides;

[0037] - in the ceramic, preferably in the form of a CMC, the total SiO2+Al2O3+ZrO2+Cr2O3 proportion, calculated as a percentage by weight based on the oxides, is preferably greater than 80%, preferably greater than 90%, preferably greater than 95%;

[0038] - the CMC comprises more than 20% and less than 80% by volume of fibers, the remainder being composed of matrix;

[0039] - the fibers consist of more than 90%, preferably more than 99%, preferably 100% by weight of oxides, preferably consist of oxides;

[0040] - the fibers preferably contain more than 50% Al2O3 or SiO2 or ZrO2;

[0041] - the fibers are arranged in the form of a woven fabric;

[0042] - the matrix consists of more than 90% by weight, preferably more than 99% by weight, preferably 100% by weight of oxides;

[0043] - the matrix comprises Al2O3 and / or SiO2 and / or ZrO2 and / or Cr2O3;

[0044] - in the matrix, the total SiO2+Al2O3+ZrO2+Cr2O3 proportion, calculated as a percentage by weight based on oxides, is preferably greater than 80%, preferably greater than 90%, preferably greater than 95%;

[0045] - the temperature of the area to be repaired is higher than 400° C., preferably higher than 500° C., preferably higher than 600° C., preferably higher than 700° C., preferably higher than 800° C., preferably higher than 900° C.;

[0046] - step a) involves introducing at least one element of said internal formwork into the furnace through a passage in a first configuration, and then deploying said formwork element from the first configuration into a second configuration incompatible with the removal of said formwork element through said passage, that is to say so that said formwork element has a dimension that, in the second configuration, prevents it from passing through a passage through the outer shell of the furnace;

[0047] - the formwork element is folded in a first configuration and unfolded in a second configuration;

[0048] - The channel:

[0049] - caused by erosion in the furnace, or

[0050] - resulting from the disassembly of the burner and / or electrodes, or

[0051] - made by the operator in order to introduce the formwork elements into the furnace and to be filled again before the furnace is put back into operation;

[0052] - step a) involves using at least one formwork element having a concave shape, preferably in the form of a cavity which, in the use position, faces the inner surface of the furnace, in order to interact with said inner surface to produce said mould;

[0053] - step a) involves using at least one formwork element having an undercut region (that is to say a region which, due to its shape, hinders the removal of the formwork element after the hardening of the repair product);

[0054] - step a) involves using at least one formwork element in the form of a plate or non-plate, the thickness of the plate being greater than 3 mm, preferably greater than 8 mm and / or less than 50 mm, preferably less than 40 mm, preferably less than 30 mm, preferably less than 20 mm, preferably less than 15 mm;

[0055] - step a) involves shaping the internal formwork so that the mould closely follows the area to be repaired, that is to say so that the shape before the furnace erosion can be restored after step b);

[0056] - the production of the portion of the internal formwork made of ceramic, preferably in the form of a ceramic matrix composite material, consists in leaving an impression on a replica of the portion of the furnace comprising the area to be repaired, before the ablation of the furnace leads to the area to be repaired;

[0057] - at least one element of the internal formwork has the form of a portion of the furnace that protrudes into the furnace, in particular the surface of an interstitial brick that is initially exposed to the furnace interior, before said portion disappears due to erosion;

[0058] The internal formwork comprises a plate made of ceramic (preferably in the form of a ceramic matrix composite material) having two large faces substantially parallel to each other, the surface area of ​​the large faces (in cm 2 ) to the thickness (in cm, measured between the two large faces) is greater than 30 cm, preferably greater than 50 cm, preferably greater than 100 cm, preferably greater than 200 cm, preferably greater than 500 cm, preferably greater than 1000 cm, preferably greater than 2000 cm, and / or less than 250,000, preferably less than 200,000, preferably less than 150,000, preferably less than 100,000, preferably less than 50,000, preferably less than 10,000, preferably less than 8,000, preferably less than 5,000, the surface area of ​​each large face of the plate preferably being greater than 1000 cm 2 , preferably greater than 1500cm 2 , preferably greater than 2000cm 2 , preferably greater than 2500cm 2 , and / or less than 10000cm 2 , preferably less than 8000cm 2 , preferably less than 5000cm 2 ;

[0059] - step a) involves using at least one formwork element having a flat shape, that is to say a panel;

[0060] - step a) involves using at least one formwork element having a shape running along at least 3 faces, preferably at least 4 faces, or even 5 faces of a glass furnace refractory block, in particular an interstitial brick;

[0061] - step a) involves using at least one formwork element having a shape running along a large face (e.g. a rectangle) and along two small faces arranged along opposite sides of the large face (e.g. along two small sides or two large sides of a large rectangular face);

[0062] - step a) involves holding the element of the internal formwork in the position of use using an appendage, preferably tubular, made of a ceramic (preferably in the form of CMC), preferably the same ceramic (preferably in the form of CMC) as the formwork element;

[0063] - step a) involves positioning one or more tubes made of ceramic (preferably in the form of CMC) and / or one or more metal rods (preferably cooled by water circulation) to hold the internal formwork in place;

[0064] - step a) involves using formwork elements and preferably accessories made entirely of ceramic, preferably in the form of CMC, so that the internal formwork is made entirely of ceramic, preferably in the form of CMC;

[0065] - step a) involves the use of formwork elements and preferably accessories made entirely of ceramic, preferably in the form of CMC, which are preferably not cooled, in particular not cooled by water circulation;

[0066] - at least one element of the internal formwork made of ceramic, preferably in the form of CMC, has through-holes and / or recesses arranged to be filled with the repair product during step b);

[0067] - preferably, the weight of the formwork elements, preferably the weight of more than 50% of the formwork elements by number, preferably the weight of each formwork element is greater than 3 kg, preferably greater than 4 kg and / or preferably less than 50 kg, preferably less than 40 kg, preferably less than 30 kg, preferably less than 20 kg;

[0068] Preferably, the maximum dimension of the formwork elements, preferably more than 30% by number of the maximum dimensions of the formwork elements, preferably more than 50% by number of the maximum dimensions of the formwork elements, is greater than 400 mm, preferably greater than 600 mm and preferably less than 1600 mm, preferably less than 1400 mm;

[0069] - step b) involves introducing the repair product into the area to be repaired by passing it through a channel created by furnace erosion, which channel is optionally the same as the channel introduced into the internal formwork element;

[0070] - step b) involves filling the mould by passing the repair product through at least one nozzle, preferably previously introduced into the area to be repaired;

[0071] - the nozzle is provided with radial discharge holes through which the repair product passes, the radial direction being relative to the supply direction of the nozzle;

[0072] - The nozzle penetrates the internal formwork or the wall of the furnace which specifically delimits the area to be repaired;

[0073] a first end of the nozzle bears against the surface of the internal formwork, preferably inserted into a recess in the surface of the internal formwork, and a second end of the nozzle is located on the outside of the area to be repaired, inside or outside the furnace;

[0074] a first end of the nozzle bears against an inner surface of the furnace defining the area to be repaired, preferably inserted in a recess in the surface of the furnace defining the area to be repaired, and a second end of the nozzle is located on the outside of the area to be repaired, inside or outside the furnace;

[0075] - one or more nozzles are made of a ceramic, preferably sintered, preferably having a similar, preferably identical, chemical composition as the hardened, preferably sintered, restoration product;

[0076] - After step b), the method comprises a step 5) of hardening, preferably sintering, the repair product introduced into the mold;

[0077] In step b), the hardened, preferably sintered, restoration product obtained consists of a plurality of components, the proportions of the components of the hardened, preferably sintered restoration product, preferably any component of the hardened, preferably sintered restoration product being present in a proportion greater than 5% by weight based on oxides:

[0078] - differs by less than 20%, preferably by less than 10%, from the proportions of said components in said ceramic (preferably in the form of CMC), and / or

[0079] - differs by less than 20%, preferably by less than 10%, from the proportions of said components in the zone of the furnace delimiting the zone to be repaired, and / or

[0080] - differs from the proportion of said components in said nozzle by less than 20%, preferably less than 10%;

[0081] - after said repair, the internal templates and / or nozzles are discarded in the area to be repaired, that is to say they are not removed before the furnace is put back into operation;

[0082] - The method comprises the following steps before step a):

[0083] - if the area to be repaired is at least partially defined by a surface of a trough of the furnace in contact with the molten glass bath, at least partially draining the molten glass from the trough in order to expose the area to be repaired;

[0084] And, after step b), the method comprises the following steps:

[0085] - introducing the glass composition to be melted into the tank, maintaining the temperature of the furnace in the area to be repaired during all the steps of the method;

[0086] After exposing the area to be repaired, the method comprises a step of rinsing the area to be repaired.

[0087] The invention also relates to a glass melting furnace comprising at least one zone repaired by the method according to the invention.

[0088] According to a second main aspect, the invention proposes a repair product injection nozzle, in particular a nozzle for a glass melting furnace, comprising

[0089] a supply hole through which the repair product is intended to enter the nozzle, and

[0090] - a hole for discharging the repair product from the nozzle, which hole is in fluid communication with the supply orifice and opens out to the outside of the nozzle through a discharge opening oriented in a discharge direction radial to the axis of the nozzle.

[0091] The nozzle according to the present invention may also include one or more of the following optional and preferred features:

[0092] - the axis of the nozzle extends along the length of the nozzle;

[0093] - the axis of the nozzle is parallel to, preferably coincident with, the axis of the supply orifice;

[0094] The nozzle is made of ceramic, which preferably consists of oxides accounting for more than 90% by weight, preferably more than 95% by weight, preferably more than 98% by weight, preferably more than 99% by weight, preferably more than 99.5% by weight;

[0095] - Proportions of the components of the nozzle, preferably any component present in a proportion greater than 5% by weight based on the oxides:

[0096] - differs by less than 20%, preferably by less than 10%, from the proportions of said components in the zone delimiting the area to be repaired in the furnace, and / or

[0097] - differs from the proportions of said components in the hardened, preferably sintered, restorative product by less than 20%, preferably by less than 10%;

[0098] The nozzle has more than 1, preferably more than 3, preferably more than 5, preferably more than 10, preferably more than 20, and / or less than 100, preferably less than 50 discharge openings;

[0099] - the discharge hole, preferably each discharge hole, is a cylindrical hole, preferably having a circular or oval, preferably circular, cross section;

[0100] - the discharge openings of the discharge holes are evenly distributed over at least a portion of the outer surface of the nozzle, preferably over a cylindrical portion of the outer surface of the nozzle;

[0101] The discharge opening of the discharge hole, preferably each discharge opening, has an equivalent diameter greater than 8 mm, preferably greater than 10 mm, and / or less than 50 mm, preferably less than 40 mm, preferably less than 30 mm, preferably less than 25 mm;

[0102] - the nozzle has the general shape of a tube, preferably closed at one end, the axis of the nozzle being the axis of said tube;

[0103] - the nozzle has a cylindrical overall shape, preferably with a circular cross section, one end of the nozzle being preferably closed by an end wall;

[0104] The nozzle has a wall of substantially constant thickness, preferably greater than 5 mm, preferably greater than 7 mm, preferably greater than 10 mm, and preferably less than 30 mm, preferably less than 25 mm, preferably less than 20 mm;

[0105] The nozzle has an equivalent inner diameter greater than 40 mm, and preferably less than 200 mm, preferably less than 150 mm, preferably less than 100 mm.

[0106] In the thermal repair method according to the invention comprising steps a) and b), preferably at least one nozzle according to the invention for injecting the repair product is used.

[0107] In general, the present invention proposes a method for repairing an area in a glass melting furnace (referred to as the "area to be repaired"), preferably at a temperature above 300°C, comprising the following steps:

[0108] a') Installing the internal formwork at the point of use so as to create a mould around the area to be repaired;

[0109] b') filling the mould with the repair product, preferably by casting,

[0110] At least a portion of the inner formwork is preferably made of ceramic, preferably in the form of CMC,

[0111] The nozzle according to the invention is installed in step a') in a supply position in which at least one discharge opening, preferably each injection opening, opens into the area to be repaired and at least one supply opening, preferably each supply opening, leads out of the area to be repaired, preferably out of the furnace.

[0112] Preferably, in the supply position, one end of the nozzle, preferably the end of the nozzle opposite the supply orifice, bears against, preferably is fixed to, a surface delimiting the area to be repaired, in particular the surface of an internal template or the inner surface 29 of the furnace defined by the tank and the superstructure of the furnace. This fixing preferably results in the insertion of said nozzle end into a recess formed in the surface of the internal template or the inner surface of the furnace, said recess preferably having a shape complementary to said end.

[0113] Preferably, in the supply position the nozzle passes through a wall of the furnace, for example a side wall of the furnace trough, and is preferably fixed to an inner formwork, or passes through an inner formwork and is preferably fixed to a wall of the furnace.

[0114] The support of the nozzle, preferably the fixing of the nozzle, advantageously increases the rigidity of the internal formwork. The presence of the nozzle may also advantageously increase the strength of the repair by anchoring the repair product after it has hardened.

[0115] The nozzle is preferably discarded in the furnace after the repair. Thus, it can help to anchor the repair product. This in turn also makes the repair method easier.

[0116] Preferably, the method according to the second main aspect of the invention is a repair method according to the first main aspect of the invention, and vice versa. In particular, step a') may include one or more optional or non-optional features of step a), and step b') may include one or more optional or non-optional features of step b).

[0117] The present invention also relates to a method comprising the following steps:

[0118] 2) preferably flushing the area to be repaired;

[0119] 3) optionally reducing the temperature in the furnace to a temperature above 300° C.;

[0120] 4) implementing steps a) and b) or steps a') and b');

[0121] 5) Preferably, especially when the method includes step 3), the temperature of the furnace is increased and maintained between 900° C. and 1400° C. to sinter the repaired product;

[0122] 6) Introducing the glass composition to be melted into the tank and, if the method comprises step 3), raising the temperature of the furnace to an operating temperature that causes the composition to melt.

[0123] The method preferably comprises the step 2) of flushing the area to be repaired.

[0124] In one embodiment, the method comprises step 3) of reducing the temperature within the furnace to a temperature above 900°C and below 1500°C and step 5) of maintaining the furnace at a temperature between 900°C and 1400°C.

[0125] The method preferably comprises step 5), wherein the temperature is maintained for a period of time longer than 8 hours and shorter than 15 hours.

[0126] In a first specific embodiment, the area to be repaired is at least partially defined by a surface of the tank of the furnace in contact with the molten glass bath, and the method comprises, before step 2), the following steps:

[0127] 1) At least partially draining the molten glass from the tank to fully expose the area to be repaired.

[0128] In a second particular embodiment, the area to be repaired is completely delimited by surfaces of the trough of the furnace that are not in contact with the molten glass bath, and the method does not comprise step 1). BRIEF DESCRIPTION OF THE DRAWINGS

[0129] Other features and advantages of the present invention will become more apparent upon examination of the following description and accompanying drawings, in which:

[0130] -[ Figure 1 ] Figure 1 It is described in the introduction, schematically showing a half cross section of a glass furnace before ablation;

[0131] - Figure 2 [ Figure 2 ] schematically shows the erosion after Figure 1 The furnace in

[0132] - Figure 3 [ Figure 3 ] schematically illustrates the method according to the present invention;

[0133] - Figure 4 [ Figure 4 ] schematically shows the partition area to be repaired;

[0134] - Figure 5 [ Figure 5 ] schematically shows an example of a nozzle for delivering a repair product to an area to be repaired according to the present invention;

[0135] - Figure 6 [ Figure 6 ] schematically illustrates a first step for generating a template in one embodiment of the present invention;

[0136] - Figure 7 [ Figure 7 ] schematically shows Figure 6 A second step for generating a template in an embodiment of the present invention;

[0137] - Figure 8 [ Figure 8 ] shows an example of a template according to the present invention;

[0138] - Fig. 9 [ Fig. 9 ] shows an example of an internal template element having through holes. DETAILED DESCRIPTION

[0139] definition

[0140] The "template" is the portion of the "mold" into which the repair product is introduced.

[0141] A "template" is produced by assembling one or more "template elements" and positioning the one or more assembled template elements in a "position of use." The portion of the mold defined by the template is supplemented by a portion of the furnace interior surface to form the mold.

[0142] In addition to the formwork elements, the formwork also includes "accessories", which are used to assemble the formwork elements and fix them in place and do not come into contact with the repair material during the repair process. In contrast to the accessories, the formwork elements are the parts that come into contact with the repair material during the repair process.

[0143] The area to be repaired can be divided by partitions. Partitions are considered formwork elements.

[0144] "Passages" are holes through the outer shell of the furnace, allowing communication between the interior and exterior of the furnace.

[0145] The "equivalent diameter" of a surface is the diameter of a disk having the same area as that surface.

[0146] "Unformed product" refers to the dry granular mixture.

[0147] A product “made of a certain material” or a product “having a certain material” is understood to mean a product consisting of more than 95%, more than 98%, preferably substantially 100% by weight of said material.

[0148] "Refractory materials" are understood to mean materials with a melting point above 1500° C. This definition is generally adopted by those skilled in the art and is cited in "Matériaux réfractaires et céramiques techniques (éléments de céramurgie et de technologie [Engineering refractory materials and ceramic materials (ceramics and technical components))]" by G. Aliprandi, published Septima Paris, 1979. This publication also gives examples of refractory materials, in particular oxides, carbides and nitrides, on pages 297 to 301.

[0149] The "glass transition temperature" of a glass is understood to mean the temperature at which the glass changes from a solid state to a viscous state. The glass transition temperature can be determined by differential thermal analysis (DTA). The glass transition temperature is the temperature at which the glass exhibits a temperature substantially equal to 10 12The temperature at which a glass is below its glass transition temperature is considered to be "solid".

[0150] A "thermoadhesive" is understood to be a component which has a melting point above 600° C. and which, after hardening under the effect of a drop in temperature, is able to bind together the particles mixed therewith.

[0151] The maximum particle size is the 99.5% (D 99.5 ) percentile, which corresponds to the 99.5% weight percentage on the cumulative particle size distribution curve of the powder particle size, where the particle size is classified in ascending order. The particle size distribution and the maximum particle size can be determined using a laser particle size analyzer. The laser particle size analyzer can be Partica LA-950 from Horiba.

[0152] "Impurities" are to be understood as unavoidable components that are unavoidably introduced with the raw materials or are produced by reactions with these components. Impurities are not necessary components, but only acceptable components. Preferably, the amount of impurities is less than 2%, less than 1%, less than 0.5%, or even substantially zero.

[0153] "Self-flowing under hot conditions" is understood to mean a repair product that is able to spread under its own inherent weight and fill the mold without causing segregation in a temperature range of 300°C to 1550°C. Segregation is considered to have occurred when the flow surface of the product obtained after placing the repair product and sintering exhibits a milky surface layer extending from said flow surface for more than 3 mm or more. This milky surface layer can be easily demonstrated by sawing in a plane perpendicular to the flow surface after the product has been dried or sintered.

[0154] AZS products are products, preferably fused products, whose main components are aluminum oxide (Al2O3), zirconium oxide (ZrO2) and silicon dioxide (SiO2). In other words, aluminum oxide, zirconium oxide and silicon dioxide are the components with the highest weight proportion. These products are very suitable for the manufacture of glass furnaces. More specifically, current AZS products are mainly used in areas that come into contact with molten glass, but also in the superstructure of glass furnaces. AZS products include in particular the products sold by Saint-Gobain SEFPRO, such as ER-1681, ER-1685 or ER-1711.

[0155] When ZrO2 or zirconium oxide is mentioned, it is understood to be ZrO2 and trace amounts of HfO2. This is because a small amount of HfO2, which is chemically inseparable from ZrO2 and exhibits similar properties, is always naturally present in the zirconium oxide source in a proportion of usually less than 2% during the melting process. Therefore, hafnium oxide is not considered an impurity. The content of HfO2 in the AZS particles is preferably less than 5%, less than 3%, less than 2%.

[0156] "Ceramic matrix composite" or "CMC" is generally understood to be a ceramic consisting of a textile made of ceramic reinforced by a ceramic matrix.

[0157] A "textile" is a combination of fibers, which may be yarns, and in particular a combination of yarns. The textile typically comprises 20% to 80% of the volume of the CMC, with the remainder to 100% being the matrix.

[0158] In general, when referring to volume percentages relative to an object, such as CMC (e.g., percentage of fibers) or a matrix of CMC (as described in the previous sentence), the volume considered is the volume of the object defined by its outer surface, that is, it includes the empty space inside the object.

[0159] "Fiber" refers to a filament whose length is greater than 5 times its equivalent diameter. The "equivalent diameter" of a fiber is the diameter of a disk having the same surface area as its mid-length cross section.

[0160] In textiles, the fibers may be assembled randomly, such as in felt or paper, or along one or more preferred directions, preferably in the form of yarns, which themselves are preferably in the form of one or more woven fabrics. The yarns of textiles may be:

[0161] - a "single yarn", which is a combination of fibers having a cross-section comprising more than 10 and preferably less than 500,000 fibers, and having a length greater than 5 times the diameter, or

[0162] - A "combination yarn" which is a combination of single yarns, the cross section of which preferably comprises more than 2 and preferably less than 500 single yarns.

[0163] Textiles may in particular:

[0164] - an organized structure of individual fibers or combinations of fibers and / or yarns, in particular a knitted or woven fabric, or

[0165] - Random structures of single or combined fibers and / or yarns, such as a web, and / or fibers not bound in yarn form, such as paper or felt, which are not preferred.

[0166] A "woven fabric" consists of a network of parallel warp yarns and weft yarns running transversely through the network.

[0167] A "knitted fabric" consists of a network of yarns in the form of a loop, which may be reinforced by one or more groups of yarns extending substantially parallel to one another, said one or more groups of yarns being trapped in said loop.

[0168] The "mat" consists of a group of parallel yarns.

[0169] "Ceramics" should be understood as products that are neither metallic nor organic. Within the scope of the present invention, carbon is considered a ceramic product.

[0170] "Sialon" SiAlON is an oxynitride of at least one of the elements Si, Al, and N, in particular a compound satisfying one of the following formulas:

[0171] -Si x Al y O u N v , where:

[0172] -x is greater than or equal to 0, greater than 0.05, greater than 0.1, or greater than 0.2, and less than or equal to 1, less than or equal to 0.8, or less than or equal to 0.4,

[0173] -y is greater than or equal to 0, or greater than 0.1, greater than 0.3, or greater than 0.5, and less than or equal to 1,

[0174] -u is greater than 0, greater than 0.1, or greater than 0.2, and less than or equal to 1, or less than or equal to 0.7,

[0175] -v is greater than 0, greater than 0.1, greater than 0.2, or greater than 0.5, or greater than 0.7, and less than or equal to 1,

[0176] -x + y > 0,

[0177] where x, y, u, and v are stoichiometric indices normalized with respect to the highest value, which is equal to 1;

[0178] -Me x Si 12-(m+n) Al (m+n) O n N 16-n , where 0 ≤ x ≤ 2, Me is a cation selected from the group consisting of lanthanide elements, Fe, Y, Ca, Li, and mixtures thereof, 0 ≤ m ≤ 12, 0 ≤ n ≤ 12, and 0 < n + m ≤ 12. According to this formula, SiAlON is commonly referred to as "α'-SiAlON" or "SiAlON-α'".

[0179] Unless otherwise specified, all percentages are weight percentages based on oxides. The weight ratios of the elements are expressed in the form of the most stable oxides.

[0180] "Comprising" or "including" or "having" or "exhibiting" should not be construed as restrictive.

[0181] Detailed Description

[0182] The preamble has described Figure 1 and Figure 2, now refer to Figure 3 .

[0183] Hotfixes

[0184] The method according to the invention is used for the thermal repair of areas of a glass melting furnace.

[0185] The area 30 to be repaired can be located in particular in the tank 12 , preferably in the side walls 22 and / or the superstructure 16 of the tank, in particular in the middle layer 18 and / or the side walls 26 of the superstructure.

[0186] The invention is particularly suitable for repairing the side walls 22 or superstructures of tanks. In particular, it is necessary to retain the repair product to avoid it flowing out due to gravity. This is generally not a problem for the repair of the bottom plate. The use of formwork elements made of ceramic, in particular in the form of plates, and in particular made of ceramics in the form of CMCs, advantageously makes it possible to produce a formwork that does not require cooling. Therefore, such a formwork can be lighter (especially if it is realized by thin plates). In addition, since there is no cooling and it can be left in place after the repair, such a formwork can be installed very quickly and does not need to be disassembled. This in turn advantageously reduces the downtime of the furnace for repair. Finally, the formwork can have a complex shape.

[0187] The region to be repaired can be in the form of a through cavity or a blind cavity, for example a recessed region, in particular a region recessed by erosion, which opens into the furnace, for example a trough.

[0188] In one embodiment, particularly for repairing a tank that initially contains a bath of molten glass in contact with the area to be repaired, the method includes the step of 1) at least partially draining molten glass from the tank to expose the area to be repaired.

[0189] Thus, the trough of the furnace is at least partially drained of the molten glass it contains until the area to be repaired is exposed. This draining can be performed by any technique known to those skilled in the art.

[0190] For example, molten glass may be discharged from the furnace through channels made in the bottom plate or through channels formed by removing one or more electrodes or one or more burners.

[0191] Step 1) is optional for repairing areas not in contact with the molten glass bath.

[0192] In step 2), which is optional but preferred, the area to be repaired is rinsed, that is to say cleaned of glass residues, by any conventional technique. Preferably, a product designed to increase the fluidity of the molten glass is sprayed at least on the area to be repaired. The fluidized glass can thereby be more easily discharged from the furnace. The fluidized product is preferably selected from sodium sulfate, sodium carbonate, sodium hydroxide and mixtures thereof.

[0193] In step 3), which is optional, the temperature within the furnace may be reduced to a temperature preferably greater than 400°C, preferably greater than 500°C, preferably greater than 600°C, preferably greater than 700°C, preferably greater than 800°C, preferably greater than 900°C, and preferably less than 1550°C, preferably less than 1500°C, or in fact less than 1450°C or 1400°C.

[0194] In one embodiment, the repair product used in step b) comprises a thermal adhesive and in step 3) the temperature in the furnace is reduced to a temperature at which the thermal adhesive is not in a solid state. In particular, when the thermal adhesive is a glass, the temperature in the furnace is reduced to a temperature that is still above the glass transition temperature of the glass. The glass is preferably selected such that its glass transition temperature is between 600°C and 1350°C, preferably between 900°C and 1350°C, more preferably between 1000°C and 1300°C, preferably between 1150°C and 1250°C.

[0195] In step 4), the repair product is put into place according to steps a) and b).

[0196] In step a), the area to be repaired is defined using a template 32 in order to form, together with a furnace, a mold for the repaired product.

[0197] The template 32 includes an inner template 32i which defines the mold 36 inside the furnace. Figure 2 The dashed line shown in the figure extends inside the furnace. The inner template particularly follows the opening of the area to be repaired 301 in the form of a cavity.

[0198] When the area to be repaired passes through a furnace, in particular a tank, such as the area to be repaired 303, the template 32 preferably includes an external template (not shown), which defines an external opening of the area to be repaired, through which it is led out of the furnace, thereby retaining the repair product before it hardens (preferably sintered).

[0199] According to the invention, at least a portion of the inner formwork, preferably all of the inner formwork, is made of ceramic, preferably in the form of CMC.

[0200] In one embodiment, at least a portion of the outer formwork, or indeed all of the outer formwork, is made of ceramic, preferably in the form of a CMC.

[0201] Preferably, in particular when the area to be repaired is at least partially defined by the surface of the tank of the furnace, at least a part of the internal template, preferably all of the internal template, and optionally the external template and / or accessories are made of ceramic, preferably in the form of CMC, which consists of oxides accounting for more than 90% of its weight, preferably more than 95% of its weight, preferably more than 98% of its weight, preferably more than 99% of its weight, preferably more than 99.5% of its weight. This advantageously improves the compatibility of the ceramic, especially the ceramic in the form of CMC, with the molten glass during normal use of the furnace.

[0202] The outer template is preferably made of the same material as the plating that may already be present.In one embodiment, the outer template is made of a ceramic in the form of a CMC, which is preferably the same ceramic as the inner template.

[0203] Ceramics, particularly in the form of CMCs, may be manufactured by any conventional process.

[0204] In particular, the ceramic can be produced by casting, pressing, vibrocasting or melting methods. The formwork elements made of ceramic can be obtained directly according to these methods or processed into blocks obtained according to these methods.

[0205] Those skilled in the art will know to adjust the parameters of the chosen ceramic manufacturing process, in particular determining the particle size of the raw materials, the water content during forming, and the sintering temperature (if the ceramic is sintered).

[0206] The manufacture of CMCs may include in particular the following steps:

[0207] i) disposing a slurry on or in the textile that is capable of forming a ceramic matrix after consolidation;

[0208] ii) before or after step i), shaping the textile;

[0209] iii) consolidating the preform obtained after the preceding steps, preferably by drying and / or sintering, to form said matrix and obtain a CMC.

[0210] In step i), the textile is a group of fibers, preferably a group of fibers combined in the form of a yarn, the yarn typically comprising several hundred to several thousand fibers. The fibers, preferably the yarns, are preferably greater than 50 mm in length, or indeed greater than 100 mm in length. In one embodiment, the fibers, preferably the yarns, are arranged in the form of at least one woven fabric.

[0211] The textile can in particular be in the form of a felt, a mat (for example a mat consisting of yarns extending essentially parallel to one another (these yarns are called "unidirectional fibers")), a knitted fabric, a woven fabric (that is to say a woven textile), or a stack of one or more felts and / or mats, and / or knitted fabrics and / or woven fabrics, of disordered yarns or fibers.

[0212] The textile is preferably in the form of a felt, or a woven fabric, or a mat, or a stack of (one or more) felts and / or (one or more) mats and / or (one or more) woven fabrics. The stack of woven fabrics and / or mats can be produced such that the yarns of the various woven fabrics or mats extend essentially in the same direction, or in 2, 3, 5, 5 or 6 different directions, depending in particular on the desired mechanical properties.

[0213] Preferably, at least some, preferably all, of the ceramic fibers of the textile, possibly combined in the form of single yarns and / or combined yarns, are:

[0214] - fibers comprising more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides, and / or

[0215] - fibres comprising more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of silicon carbide, and / or

[0216] - Fibres comprising more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of carbon.

[0217] Preferably, the fibers of the textile contain more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides.

[0218] Preferably, at least some, preferably all, of the ceramic fibers are:

[0219] - Fibers containing more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides and having a chemical composition such that, in percentage by weight based on the oxides, SiO2+Al2O3+ZrO2>50%, preferably SiO2+Al2O3+ZrO2>60%, or indeed SiO2+Al2O3+ZrO2>70%, or indeed SiO2+Al2O3+ZrO2>80%, or indeed SiO2+Al2O3+ZrO2>90%, and / or

[0220] - fibers containing more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides and having a chemical composition such that, in percentage by weight based on oxides, SiO2>70%, preferably SiO2>80%, preferably SiO2>90%, or indeed SiO2>99%, and / or

[0221] - Fibers containing more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% oxides by weight and having a chemical composition such that, in terms of weight percentage based on oxides, Al2O3>65%, preferably Al2O3>70%, or indeed Al2O3>80%, or indeed Al2O3>90%, or indeed Al2O3>95%.

[0222] It is further preferred that at least some, preferably all, of the ceramic fibers are:

[0223] - fibres consisting of more than 95%, preferably more than 98%, preferably more than 99%, preferably substantially 100% by weight of aluminium oxide, and / or

[0224] - fibres consisting of more than 95%, preferably more than 98%, preferably more than 99%, preferably substantially 100% by weight of silica, preferably fibres consisting of more than 95%, preferably more than 98% amorphous, and / or

[0225] - fibres consisting of more than 95%, preferably more than 98%, preferably more than 99%, preferably substantially 100% by weight of mullite and corundum, and / or

[0226] - Fibers consisting of more than 95%, preferably more than 98%, preferably more than 99%, preferably substantially 100% by weight of glass (preferably leached glass) and mixtures thereof.

[0227] All fibers preferably have the same composition.

[0228] The slurry can be arranged on or in the textile, for example, by impregnation.The stack can be produced by pressing or vacuum forming, preferably after impregnation.

[0229] The preparation of slurries is well known to those skilled in the art. Slurries are generally suspensions, such as water-based or organic solvent suspensions, which contain:

[0230] - ceramic particles and / or ceramic particle precursors (that is to say compounds which are converted into ceramic particles during the CMC manufacturing process, in particular during hardening, in particular during sintering), and

[0231] -Optional dispersants, plasticizers, lubricants and / or temporary binders.

[0232] The composition of the slurry, the size distribution of the ceramic particles or ceramic precursors, and the mineral filler of the slurry are all adapted to the type of fiber and the forming technique. For example, the slurry can be arranged around or in the textile, especially in the form of a direct laminate, at ambient temperature or higher, by soaking, injection, infiltration, or deposition, at atmospheric pressure or higher pressure, or by vacuum forming.

[0233] In step ii), the obtained fabric is shaped, preferably impregnated with a slurry. The desired shape is preferably the final shape of the CMC. However, in one embodiment, the shape can be modified after the matrix has hardened, for example by machining or deformation.

[0234] Preferably, in order to produce the internal formwork, the textile is shaped so that the shape of the CMC is adapted so that after the formwork is installed, the repair material replaces only the material removed by ablation, preferably all the material removed by ablation. In other words, the shape is preferably determined so that in the use position, the internal formwork element made of CMC follows Figure 2 The dotted line in .

[0235] The shape can be imparted by leaving an impression on a replica of the part of the furnace to be repaired with a textile before erosion occurs (before or preferably after the introduction of the slurry). The mold is then a "negative" of the area to be repaired. For example, if the area to be repaired is a gap brick, the CMC can be produced by depositing a textile (preferably a woven fabric or a superposition of multiple woven fabrics) on a replica of the gap brick before or after impregnation with the slurry but before consolidation, so that this textile closely follows the surface of the gap brick, at least in the area corresponding to the area to be repaired. The use of ceramics, in particular ceramics in the form of CMCs, advantageously makes it possible to easily produce complex shapes that may not be developable. Therefore, the repair can accurately reconstruct the original contour of the inner surface of the furnace.

[0236] CMC can be manufactured by stacking prepregs, each consisting of a woven fabric impregnated with a slurry of ceramic particles. The prepregs are flexible so that they can be given a desired shape.

[0237] In step iii), consolidation is preferably carried out before mounting the formwork, preferably by sintering, in order to make this mounting easier.

[0238] The properties of ceramics in general, and in particular in the form of CMCs, are determined by their manufacturing process.

[0239] Preferably, the ceramic, preferably in the form of a CMC, has one or more of the following optional features:

[0240] - preferably a sintered ceramic, preferably in the form of a CMC;

[0241] The ceramic, preferably in the form of a CMC, preferably has an open porosity measured by imbibition according to the Archimedean principle of buoyancy of greater than 10%, preferably greater than 15%, and less than 50%, preferably less than 45%, preferably less than 40%;

[0242] The ceramic is in the form of a CMC and preferably has an open porosity greater than 25%, preferably greater than 30%, measured by imbibition according to the Archimedean buoyancy principle;

[0243] - the ceramic is not in the form of a CMC and preferably has an open porosity of preferably less than 30%, preferably less than 25%, measured by imbibition according to the Archimedean buoyancy principle;

[0244] - the ceramic, preferably in the form of a CMC, preferably consists of more than 90% by weight, preferably more than 95% by weight, preferably more than 98% by weight, preferably more than 99% by weight, preferably more than 99.5% by weight of oxides;

[0245] - the CMC preferably contains more than 20%, preferably more than 25%, preferably more than 30%, preferably more than 40%, preferably more than 50%, preferably more than 60%, and / or less than 80%, preferably less than 70% fiber volume;

[0246] - CMC comprises fibers consisting of more than 90%, preferably more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides;

[0247] At least some, preferably all, of the ceramic fibers are:

[0248] - Fibers containing more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides and having a chemical composition such that, in percentage by weight based on the oxides, SiO2+Al2O3+ZrO2>50%, preferably SiO2+Al2O3+ZrO2>60%, or indeed SiO2+Al2O3+ZrO2>70%, or indeed SiO2+Al2O3+ZrO2>80%, or indeed SiO2+Al2O3+ZrO2>90%, and / or

[0249] - fibers containing more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides and having a chemical composition such that, in percentage by weight based on oxides, SiO2>70%, preferably SiO2>80%, preferably SiO2>90%, or indeed SiO2>99%, and / or

[0250] - Fibers containing more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% oxides by weight and having a chemical composition such that, in terms of weight percentage based on oxides, Al2O3>65%, preferably Al2O3>70%, or actually Al2O3>80%, or actually Al2O3>90%, or actually Al2O3>95%, or actually Al2O3>97%, or actually Al2O3>98%.

[0251] the ceramic is in the form of a CMC and the matrix of the CMC consists of oxides, carbides and / or nitrides and / or sialons, in particular more than 90%, preferably more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides, carbides, nitrides and / or sialons of the aforementioned type;

[0252] the ceramic is in the form of a CMC and preferably the matrix of said CMC consists of more than 90%, preferably more than 95%, preferably more than 97%, preferably more than 98%, preferably more than 99%, preferably more than 99.5% by weight of oxides;

[0253] - the matrix of the CMC preferably consists essentially entirely of oxides;

[0254] - the matrix comprises Al2O3 and / or SiO2 and / or ZrO2 and / or Cr2O3;

[0255] - The matrix of the CMC preferably comprises Al2O3 and SiO2;

[0256] - in one embodiment, the proportion of Al2O3 in the matrix of the CMC is greater than 65%, preferably greater than 70%, expressed as a percentage by weight based on the oxides of the matrix;

[0257] - in one embodiment, the proportion of SiO2 in the matrix of the CMC is greater than 15%, preferably greater than 20%, and / or less than 35%, preferably less than 30%, measured as a percentage by weight based on the oxides of the matrix;

[0258] - in one embodiment, the proportion of SiO2 in the matrix of the CMC is greater than 60%, preferably greater than 70%, preferably greater than 80%, expressed as a percentage by weight based on the oxides of the matrix;

[0259] - in one embodiment, the proportion of oxides other than Al2O3 and SiO2 in the matrix of the CMC is less than 3%, preferably less than 2%, preferably less than 1%, expressed as a percentage by weight of the oxides of the matrix;

[0260] - in one embodiment, the proportion of total Al2O3 and SiO2 in the matrix of the CMC is greater than 80%, preferably greater than 85%, preferably greater than 90%, preferably greater than 95%, measured in weight percentage based on the oxides of the matrix;

[0261] - In one embodiment, the silica of the matrix of the CMC is amorphous;

[0262] - preferably, the ceramic, preferably in the form of a CMC, has a total SiO2+Al2O3+ZrO2+Cr2O3 ratio of more than 80%, preferably more than 85%, preferably more than 90%, preferably more than 95%, preferably more than 97%, preferably more than 97%. Further preferably, the ceramic, preferably in the form of a CMC, has a total SiO2+Al2O3 ratio of more than 80%, preferably more than 85%, preferably more than 90%, preferably more than 95%, preferably more than 97%, preferably more than 97%;

[0263] In a preferred embodiment, the ceramic, preferably in the form of a CMC, has the following chemical analysis, expressed as percentages by weight based on the oxides (totaling 100%):

[0264] -SiO2: 47%-67%,

[0265] -Al2O3: 32%-52%,

[0266] - oxides other than Al2O3 and SiO2: <5%, preferably <4%, preferably <3%, preferably <2%;

[0267] In one embodiment, the ceramic, preferably in the form of a CMC, is preferably amorphous and has the following chemical analysis, expressed in weight percentages based on oxides (totaling 100%):

[0268] -SiO2:>95%, preferably>96%, preferably>97%, preferably>98%, preferably 99%;

[0269] - The ceramic is in the form of CMC and has a mass greater than 1.0 g / cm 3 , preferably greater than 1.20 g / cm 3 , preferably greater than 1.40g / cm 3 , or actually greater than 1.50g / cm 3 , and / or less than 2.00g / cm3 , preferably less than 1.90g / cm 3 , preferably less than 1.80g / cm 3 The bulk density;

[0270] - Ceramics that are not in the form of CMC and have a mass greater than 1.80 g / cm 3 , or actually greater than 2.00g / cm 3 , and / or less than 3.20g / cm 3 , preferably less than 3.00g / cm 3 , preferably less than 2.80g / cm 3 The volume density of .

[0271] The formwork is then installed by assembling these elements.

[0272] Installation of internal formwork was tricky due to the difficulty in access.

[0273] When they are in place, the formwork elements may be supported by the face or opposing faces which are exposed to the furnace in the position of use.

[0274] At least one element of the internal formwork made of CMC and / or one CMC accessory may be configured to be deformable between a first configuration designed for introduction into the furnace and a second configuration designed for a position of use. The elements of the internal formwork made of CMC and / or the CMC accessories may be foldable so as to be able to be introduced through an available access channel, such as a penetration area to be repaired, or through an access channel that can be easily created, such as by moving a burner.

[0275] Preferably, at least some elements of the internal formwork are made of ceramic, preferably CMC, which is configured to be foldable. These elements of the internal formwork may for example comprise two rigid panels connected to each other by a hinge. The hinge may be a component fixed to the two panels.

[0276] The formwork element may also comprise a plurality of panels connected to each other by hinges made of deformable refractory material, such as prepreg.

[0277] After being folded for introduction into the furnace, the formwork elements are unfolded to give them the desired shape.

[0278] Figure 6 and Figure 7 The steps for installing a formwork to rebuild the interstitial bricks 20 in one embodiment are schematically illustrated.

[0279] Figure 6The state of the gap bricks before repair can be seen, in particular the corroded area 33 which partially defines the inner surface of the furnace before repair. The dotted lines allow the gap bricks to be seen in a new state.

[0280] Two channels shown in dashed lines have been formed to connect the area to be repaired 302 with the outside of the furnace. The first channel 341 is cylindrical and is configured to introduce a nozzle 50, which will be described in more detail below. The second channel 342 has a substantially rectangular cross-section and is configured to introduce a set of template elements. The template elements include a first panel 351 and a second panel 352, respectively, and a hinge 353 connecting two adjacent edges of the first panel 351 and the second panel 352. Compared with the essentially non-deformable panels, the hinge is flexible. It is preferably made of prepreg, that is, made of a textile impregnated with a ceramic matrix precursor, so that after sintering, the hinge is made of CMC.

[0281] exist Figure 6 In the embodiment, the first panel 351 and the second panel 352 are stacked on each other by folding with the help of hinges. This compact construction makes it easier to introduce them into the furnace, as shown by the arrows.

[0282] After the second panel 352 is introduced, it is unfolded and positioned to follow the area to be repaired, e.g. Figure 7 Then, the template element forms a template 32. In this embodiment, the template 32 only includes an internal template 32i. The template defines a mold 36 through a portion of the inner surface. The internal volume of the mold 36 (such as Figure 6 The gray area in B) has a similar shape to the area to be repaired.

[0283] The nozzle 50 is then introduced through the first passage 341 so as to be led out of the furnace and into the area to be repaired.

[0284] The nozzle preferably bears against the internal formwork, preferably to help hold the formwork element in place.The end of the nozzle introduced into the area to be repaired is preferably housed in a complementary shaped recess 37 formed in the formwork.

[0285] The repair product can then be introduced into the area to be repaired through the nozzle.

[0286] Many variations are possible. In particular,

[0287] - the nozzle can be introduced into the furnace by means of the channel of the template element through which it is introduced into the furnace beforehand,

[0288] - the formwork elements can be introduced through channels that lead into the furnace but not to the area to be repaired,

[0289] -The nozzle may not be in contact with the template,

[0290] - The repair product can be introduced without the use of a nozzle, e.g. by Figure 6 The repair product is introduced by casting it on the top of the (open) mold,

[0291] The nozzle can be introduced into the area to be repaired by passing through a template and optionally anchored in a preferably complementary shaped recess formed in the inner surface of the furnace.

[0292] In one embodiment, if Figure 4 As shown, the area to be repaired is divided into at least two compartments 38 by introducing one or more partitions 40. It is worth noting that the partitioning can limit the risk of delamination of the repaired product and make the repair last longer.

[0293] The partitions are preferably determined so that each compartment has a surface area less than or equal to 25 m 2 , preferably less than 16m 2 , and / or greater than or equal to 3m 2 The base of.

[0294] In one embodiment, the separators of the compartments are made of said ceramic, preferably in the form of CMC.

[0295] In one embodiment, at least one element of the internal formwork made of ceramic, preferably in the form of CMC, has through holes and / or recesses. Filling these holes and recesses with the repair product during step b) advantageously enables better fixation of the internal formwork and enables reduction of thermal gradients in the repair product during step 5). Preferably, the average equivalent diameter of the holes is greater than 8 mm, preferably less than 20 mm, preferably less than 15 mm.

[0296] In one embodiment, the template element made of ceramic (preferably in the form of CMC) is in the form of a grid, and the pores are preferably evenly distributed, and the total surface area of ​​the pores accounts for more than 10%, preferably more than 15%, and preferably less than 50%, preferably less than 40% of the inner surface area of ​​the template element (that is, the surface area that helps to define the mold around the area to be repaired (the surface area of ​​the pores and the grid material)).

[0297] In one embodiment, the pores are located in the lower two thirds of the template element and are preferably evenly distributed. Further preferably, in the embodiment, the total surface area of ​​the pores accounts for more than 1% and less than 5% of the internal surface area of ​​the template element (the surface area of ​​the pores and the template element material).

[0298] The through holes and / or recesses can be made by any technique known to the person skilled in the art. In particular, the through holes can be made, for example, by drilling or water jet cutting in the ceramic, preferably in the form of a CMC obtained after sintering. In CMC, the through holes and / or recesses can also be made in the textile, preferably a woven fabric, which is then coated with the slurry.

[0299] Attachments are then usually used to hold the formwork elements in the position of use.

[0300] In one embodiment, the seal between the inner formwork and the inner surface of the furnace is improved by arranging a ceramic fiber mat between the inner formwork and the surface.

[0301] Figure 8 An example of an internal formwork according to the invention is shown. Particularly shown is an internal formwork 32i, in particular 3 adjacent panels 351 , 352 and 353, which are held in place by metal clamps 39, wedges 43 and cooling tubes 45.

[0302] In step b), the mould defining the area to be repaired is filled with the repair product, preferably by casting.

[0303] Repair products

[0304] The repair product may be a conventional repair product and may be prepared by any known technique.

[0305] The repair product is preferably the result of wetting the unshaped product. The wetting can be carried out by any known technique, for example in a kneader. A person skilled in the art will know how to determine the amount of solvent, preferably water, used to wet the unshaped product and obtain the repair product.

[0306] Unshaped products may in particular be:

[0307] - Repair of hot bottom AZS, especially when the area to be repaired is located on the floor of the furnace tank,

[0308] - repair thermal coating AZS, repair thermal coating Alumina or repair thermal coating Chrom50, in particular when the area to be repaired is located on the wall of a furnace tank, or

[0309] -Restoration thermal coating fused silica, when the area to be restored is located in the coronal part.

[0310] These unformatted products are marketed by Saint-Gobain Sefpro.

[0311] Preferably, the maximum particle size of the particles of the repair product or equivalently the unshaped product is less than 10 mm, preferably less than 8 mm, preferably less than 6 mm.

[0312] The particle size distribution of the repair product or equivalently the unshaped product is preferably determined such that the repair product is self-flowing under hot conditions.

[0313] Preferably, the repair product is selected so that its chemical analysis closely approximates the chemical composition of the furnace material defining the area to be repaired, preferably so that the proportion of any component of the repair product differs by less than 10% from the proportion of said component in said material.

[0314] For example, if the area to be repaired is defined by one or more refractory blocks made of AZE (alumina-zirconia-silica) products, the unshaped product used to make the repair product is preferably a repair hot bottom AZS or a repair hot coating AZS, depending on the location of the area to be repaired in the glass melting furnace. If the area to be repaired is defined by one or more refractory blocks made of AZS chromium products, the unshaped product used to make the repair product is preferably a repair hot coating Chrom50. Finally, if the area to be repaired is defined by one or more refractory blocks made of silica products, the unshaped product used to make the repair product is preferably a repair hot coating fused silica.

[0315] The repair product may be brought to the area to be repaired using any technique known to those skilled in the art.

[0316] If the area to be repaired is difficult to access, one or more channels, such as channels formed by drilling, can be formed from the outside of the furnace to the inside. These channels advantageously enable the introduction of means for transporting the repair product to the area to be repaired, such as cooling rods or nozzles.

[0317] In one embodiment, the repair product is pumped by a pump generating a suction pressure preferably less than or equal to 180 bar and is preferably delivered to the area to be repaired through a water-cooled wand or nozzle.

[0318] In one embodiment, the repair product is supplied ready for use, that is to say stored in an already wetted state. Advantageously, the filling rate of the area to be repaired can be increased and / or the number or capacity of pumps can be reduced.

[0319] Throughout step b), the area to be repaired is preferably maintained at a temperature above 300°C, preferably above 400°C, preferably above 500°C, preferably above 600°C, preferably above 700°C, preferably above 800°C, preferably above 900°C, and / or preferably below 1550°C, preferably below 1500°C.

[0320] nozzle

[0321] like Figure 4As shown, the repair product 41 is usually delivered to the area to be repaired through a tubular pipe 42 or channel, the first end of which is connected to the outlet of a pump 44 supplied by a reservoir 46 of the repair product, and the second end is free or connected to a nozzle 50, which is preferably introduced and fixed in the area to be repaired, preferably fixed to the internal template and / or the internal surface of the furnace, in particular to the part of the internal surface that defines the area to be repaired.

[0322] The nozzle is used to dispense the repair product, but preferably also to anchor in the cast repair product, and / or to help hold the internal formwork in place. The nozzle preferably helps hold the internal formwork in place after the repair product has hardened.

[0323] When the repair product emerges from the second end or nozzle 50, it is subjected to a sudden increase in temperature of the surrounding area, which may lead to, among other things, a reduction in its flowability. In order to distribute the repair product evenly, the number of nozzles may be increased.

[0324] The inventors have found that it is advantageous if the repair product can come out radially, preferably on all sides of the nozzle, preferably over the entire length.

[0325] Figure 5 A non-limiting embodiment of a nozzle 50 in a preferred embodiment of the present invention is shown.

[0326] The nozzle 50 has the general shape of a cylindrical sleeve with a circular base of axis X. The nozzle has a supply orifice 54 of axis X through which the repair product enters the nozzle. Axis X is therefore the supply direction of the nozzle.

[0327] Two circumferential through-cut recesses 58 are shown at the supply opening 54 for fixing the nozzles.

[0328] At the other end of the supply aperture, the nozzle preferably has an end wall 56. During injection of the repair product, the end wall 56 preferably extends substantially horizontally, so that the length direction of the nozzle is vertical.

[0329] The sleeve has a wall of substantially constant thickness, which is preferably greater than 5 mm, preferably greater than 7 mm, preferably greater than 10 mm, and preferably less than 30 mm, preferably less than 25 mm, preferably less than 20 mm. Its equivalent inner diameter is preferably greater than 40 mm, and preferably less than 200 mm, preferably less than 150 mm, preferably less than 100 mm.

[0330] The length of the nozzle is determined based on the shape of the area to be repaired. It can be between 1 and 10 times the equivalent inner diameter of the sleeve.

[0331] The side wall of the nozzle has a plurality of discharge holes 52, each of which emerges on the outer surface 53 of the nozzle through a respective discharge opening having an axis Y extending radially, that is to say intersecting the axis X, perpendicular to the axis X. The nozzle preferably has more than 1, preferably more than 3, preferably more than 5, preferably more than 10, preferably more than 20, and / or less than 100, preferably less than 50 discharge holes 52, identical or different.

[0332] The discharge holes 52 are preferably evenly distributed along the circumference. Along a circle with axis X intersecting the discharge holes 52, preferably along each circle with axis X intersecting the discharge holes 52, the discharge holes 52 are evenly distributed. The discharge holes intersecting the same circle with axis X form a "row" of discharge holes 52.

[0333] The discharge holes 52 are preferably evenly distributed along a direction parallel to the axis X, that is to say along the length of the nozzle. Along this direction, the nozzle preferably has more than 1 row, preferably more than 2 rows, preferably more than 3 rows, and / or less than 10 rows, preferably less than 8 rows, preferably less than 5 rows of discharge holes 52. Figure 5 There are 4 rows of nozzles in this way.

[0334] Therefore, all the discharge holes 52 preferably form a regular pattern. This further improves the uniformity of the distribution of the repair product.

[0335] Preferably, each discharge hole is a cylindrical hole, preferably with a circular or rectangular cross section, preferably a circular cross section. The discharge openings of the injection holes on the outer surface of the sleeve are preferably evenly distributed on the outer surface. This improves the uniformity of the distribution of the repair product.

[0336] Further preferably, the discharge opening of the discharge hole, preferably each discharge hole, has an equivalent diameter greater than 8 mm, preferably greater than 10 mm, and less than 50 mm, preferably less than 40 mm, preferably less than 30 mm, preferably less than 25 mm.

[0337] The nozzle is preferably formed in one piece.

[0338] Preferably, the nozzle is made of ceramic, preferably sintered. Preferably, the chemical composition of the nozzle is similar to, preferably identical to, the chemical composition of the repair product. Preferably, the proportion of any component of the repair product present in an amount greater than 5% by weight differs from the proportion of said component in the nozzle by less than 20%, preferably less than 10%. Advantageously, after the area to be repaired has been filled with the repair product, the nozzle can remain in the area to be repaired without causing, by its presence, a lack of homogeneity in the composition in the area to be repaired.

[0339] In step 5), which is optional, in particular if the method comprises step 3), the furnace is maintained in a temperature range of between 900°C and 1400°C, preferably between 1250°C and 1400°C, preferably between 1300°C and 1400°C, so as to be able to sinter the repair product, preferably for a duration longer than 8 hours, preferably longer than 10 hours, and preferably shorter than 15 hours.

[0340] In step 6), normal operation of the furnace is resumed: the glass composition to be melted is introduced into the furnace, and if the method includes step 3), the temperature of the furnace is increased to resume operation of the furnace.

[0341] Example

[0342] To illustrate the present invention, the following non-limiting examples are given.

[0343] In a first specific embodiment, in particular when the area to be repaired is located in the superstructure of a glass melting furnace, the internal formwork is made of ceramic, preferably in the form of CMC, preferably of one or more plates made of ceramic, preferably in the form of CMC, preferably held against the surrounding of the superstructure portion using one or more metal rods, preferably cooled by water circulation. If the area to be repaired leads to the outside of the furnace, a coating preferably made of ceramic, preferably in the form of CMC, constituting the external formwork is fixed so as to close the area to be repaired from the outside.

[0344] The area to be repaired is then filled with the repair product, which is preferably delivered from outside the furnace through a pipe through one or more channels formed through the outer wall of the furnace and then cast into the area to be repaired through at least one nozzle according to the invention, which is preferably arranged in the area to be repaired.

[0345] The nozzle or nozzles are made of a ceramic material, the chemical composition of which is preferably similar, preferably identical, to the chemical composition of the repair product.

[0346] Preferably, the template made of ceramic, preferably in the form of CMC, and / or the one or more nozzles are not removed after the repair product is in place.

[0347] In a second specific embodiment, in particular when the area to be repaired is located at the gap bricks, the part of the gap bricks that disappears during the use of the furnace is replaced by the repair product. The template comprises a plate made of ceramic (preferably in the form of CMC), preferably made of plates made of ceramic (preferably in the form of CMC), which are arranged to at least partially recreate the shape of the new gap bricks. One or more template elements are preferably introduced into the furnace in a folded state and then unfolded and fixed to define the area to be repaired. In one embodiment, the area to be repaired defined by the template made of ceramic (preferably in the form of CMC) is filled with the repair product through the inside of the furnace. In one embodiment, the area to be repaired defined by the template made of ceramic (preferably in the form of CMC) is filled with the repair product through the outside of the furnace.

[0348] In a third specific embodiment, in particular when the area to be repaired is caused by the erosion of the furnace tank, the molten glass is at least partially discharged. The internal template is made of ceramic (preferably in the form of CMC), preferably made of one or more plates made of ceramic (preferably in the form of CMC), which are preferably kept against the tank using one or more tubes made of ceramic (preferably in the form of CMC) and / or one or more metal rods (these metal rods are preferably cooled by water circulation). If the area to be repaired leads to the outside of the furnace, a coating constituting the external template and preferably made of ceramic (preferably in the form of CMC) is fixed to close the area to be repaired from the outside.

[0349] The area to be repaired is then filled with the repair product, which is preferably delivered from outside the furnace through a pipe through one or more channels formed through the furnace shell and then cast into the area to be repaired through at least one nozzle according to the invention, which is preferably arranged in the area to be repaired.

[0350] The nozzle or nozzles are made of a ceramic material which is preferably selected to be a material having a chemical composition similar to, preferably identical to, that of the repair product.

[0351] Preferably, the template made of ceramic, preferably in the form of CMC, and / or the one or more nozzles are not removed after the repair product is in place.

[0352] In a preferred embodiment, the elements of the internal formwork, the optional partitions arranged in the area to be repaired, and the accessories used to assemble these elements and the partitions are not removed after the repair product is in place.

[0353] Two embodiments have been realized with the same repair product, which embodiments differ in the rate at which the repair product is raised in the mould.

[0354] To make the repaired product, the unshaped product Repair Hot Overcoat AZS sold by Saint-Gobain Sefpro was mixed for 5 minutes with 10% by weight of a colloidal silica solution equal to 20% in concentration based on the unshaped product in a kneader with rotating blades and a stationary tank.

[0355] The unshaped product has the following composition by weight, based on the weight of the oxides of the unshaped product:

[0356] -Al2O3: 56%,

[0357] -SiO2: 8%,

[0358] -ZrO2: 35%,

[0359] - Other oxides: 1%.

[0360] 250 kg of repair product were prepared. This repair product was self-flowing under hot conditions.

[0361] For each example, a one-piece mold made of CMC was created.

[0362] The mould has the general shape of a cuboid, with a flat base of length equal to 600 mm, width equal to 150 mm, and side walls extending from the periphery of the base to a height equal to 450 mm, the wall thickness of said mould being substantially constant equal to 10 mm.

[0363] The thermal conductivity of the CMC components of both molds is less than 0.6Wm between 20℃ and 500℃ -1 .K -1 .

[0364] CMC is composed of:

[0365] - a superposition of woven fabrics made of leached glass fibers (whose proportion by weight of silica is greater than 90%), representing 44% of the mass of the CMC, and

[0366] - A matrix made of alumina and silica, which accounts for 56% of the CMC mass.

[0367] The CMC has an open porosity of 38%, a porosity of 1.65 g / cm 3 A bulk density of 42%, an Al2O3 proportion equal to 57%, and a proportion of other oxides equal to 1%, the proportions of Al2O3, SiO2 and other oxides being expressed in weight percentages based on the oxides of the CMC.

[0368] The two moulds were arranged in a furnace comprising a gas burner.

[0369] The furnace was then started to reach a temperature of 1200°C in 2 hours and 40 minutes, simulating the introduction of a mould made of CMC into a glass melting furnace under hot conditions. The temperature was then raised to 1500°C, with a heating rate between 1200°C and 1500°C equal to 35°C / h.

[0370] The repaired product was cast into each mould maintained at 1500°C through a metal channel arranged over an opening made in the crown of the furnace.

[0371] The repaired product was continuously cast at a flow rate substantially equal to 100 kg / min for Example 1 according to the invention and at a flow rate substantially equal to 300 kg / min for Example 2 according to the invention.

[0372] During the filling process, it was noted that the molds made of CMC were able to withstand the impact of the repaired product without breaking or opening.

[0373] After filling the mould, the temperature is maintained at 1500° C. for 24 hours. The temperature is then gradually reduced to 800° C. at a rate substantially equal to 25° C. / h. The burner is then stopped and the temperature is allowed to fall naturally without opening the furnace.

[0374] The inventors believe that this test closely replicates the conditions encountered during the repair of furnace tank components.

[0375] The sintered repair product located in each mold is then recovered.

[0376] After sawing, they have a uniform grain without cracks or internal cavities that could correspond to interruptions in supply.

[0377] Similar tests can be carried out with a one-piece mould of the same dimensions as the mould made of the CMC described above, made of the same ceramic composition as the CMC, but obtained by casting the slurry into a mould of suitable shape, without incorporating fibres, and then sintering.

[0378] The results obtained using this cast one-piece mold (not in CMC form) were similar to those obtained with previously tested molds made from CMC.

[0379] Thus, as is now clear, the present invention provides a method for thermally repairing a glass melting furnace, the method utilizing elements made of ceramic, preferably in the form of CMC, to create an internal formwork, and the method:

[0380] - enables rapid production that is well suited to the area to be repaired, in particular because ceramics, preferably in the form of CMCs, can be formed into complex shapes, in particular in order to closely follow the contours of the area to be repaired;

[0381] - makes it easier to introduce the elements into the furnace, especially when they are folded so as to be introduced through narrow passages through the furnace;

[0382] - Makes it easier to arrange these elements, as they are lightweight and can be elastically deployed;

[0383] - Allows the sacrificial formwork element, that is to say to remain in the furnace after the repair, in particular since the composition of the ceramic (preferably in the form of CMC) can be chosen to be similar to that of the repaired product.

[0384] The nozzle according to the present invention can also:

[0385] - Simultaneous casting of the repair product in several directions and at different heights, which allows rapid filling of the area to be repaired but also enables a uniform distribution without delamination;

[0386] - Sacrificial nozzles when the chemical composition of the nozzle is chosen to be similar to the chemical composition of the repair product.

[0387] Of course, the invention is not limited to the embodiments described or shown, provided by way of illustrative and non-limiting examples.

[0388] In particular, the ceramic composition and / or CMC structure of various parts of the mold plate and / or nozzle and / or attachment may be the same or different.

Claims

1. A method for thermally repairing a region to be repaired (30) in a glass melting furnace (10) 1 , 30 2 , 30 3 ), wherein the area to be repaired is at a temperature higher than 300° C., and the method The following steps are involved: a) installing an internal formwork (32i) at the location of use so as to create a mould (36) around the area to be repaired; b) filling the mould with a repair product (41), At least a portion of the inner template is made of a ceramic matrix composite material.

2. The method according to the preceding claim, in, The furnace comprises: - a tank (12) comprising side walls (22), and - superstructure (16), The area to be repaired is located in the side wall (22) of the tank and / or in the upper structure.

3. A method according to any one of the preceding claims, in, Step a) involves introducing at least one element of the internal formwork into the furnace through a passage in a first configuration and then deploying the formwork element from the first configuration into a second configuration incompatible with removal of the formwork element through the passage.

4. The method according to the immediately preceding claim, in, The formwork element is folded in the first configuration and unfolded in the second configuration.

5. The method according to any of the two preceding claims, in, The channels are produced by erosion of the furnace.

6. A method as claimed in any one of the preceding claims, in, At least one element of the inner formwork has the form of a portion of the furnace that protrudes into the furnace before the portion disappears due to erosion.

7. The method according to the immediately preceding claim, in, The elements of the internal formwork have the form of surfaces of interstitial bricks which delimit the furnace interior before the ablation.

8. A method as claimed in any one of the preceding claims, in, The production of the portion of the internal template comprises leaving an impression on a replica of the portion of the furnace including the area to be repaired, before the abrasion of the furnace leads to the area to be repaired.

9. A method as claimed in any one of the preceding claims, in, Step b) involves filling the mould by passing the repair product through a nozzle (50) provided with discharge orifices (52) which are radial with respect to the supply direction (X) of the nozzle.

10. The method according to the immediately preceding claim, in, - a first end (56) of the nozzle bears against the surface of the internal formwork and a second end of the nozzle is located outside the area to be repaired; or - the first end (56) of the nozzle bears against the inner surface of the furnace defining the area to be repaired, the second end of the nozzle being located outside the area to be repaired.

11. The method according to any of the two preceding claims, in, The nozzle is made of a ceramic, which is preferably sintered and preferably has a similar chemical composition as the hardened, preferably sintered, restoration product.

12. The method according to any one of the preceding claims, comprising, after step b), a step 5) of sintering the repair product introduced into the mould in step b), the sintered repair product obtained consisting of a plurality of components, the proportion of any component of the sintered repair product present in a proportion greater than 5% being: - differs by less than 20% from the proportions of said components in said ceramic matrix composite material, and / or - differs by less than 20% from the proportions of said composition in the zone of said furnace which delimits said zone to be repaired, and / or - when any one of claims 8 to 10 is applicable, differs by less than 20% from the proportions of said components in said nozzle, The proportions are given as weight percent based on the oxides.

13. A method as claimed in any one of the preceding claims, in, After said repair, said inner template (32i) is discarded in said area to be repaired, and / or said nozzle (50) is discarded when any one of claims 8 to 10 is applicable.

14. A method as claimed in any one of the preceding claims, in, The inner template (32i) is made entirely of ceramic-based composite material.

15. A method as claimed in any one of the preceding claims, in, At least one element of the internal formwork made of a ceramic matrix composite material has through holes and / or recesses arranged to be filled with the repair product during step b).

16. A method as claimed in any one of the preceding claims, in, At least one of the formwork elements has the form of a flat or non-flat plate, the thickness of which is greater than 3 mm and less than 50 mm.

17. A method as claimed in any one of the preceding claims, in, The internal template has: - formwork elements partially delimiting the area to be repaired, and - attachments for holding said formwork element in the position of use, The attachment is made of a ceramic matrix composite material which is the same as or different from the ceramic matrix composite material of the formwork element.

18. A method as claimed in any one of the preceding claims, in, A ceramic matrix composite material of at least a portion of the internal formwork, and / or when claim 16 is applicable, a ceramic matrix composite material of at least one accessory: - is sintered, and / or - has an open porosity greater than 25% and less than 50%, and / or - consists of more than 90% by weight of oxides, and / or - contains more than 20% and less than 80% by volume of fibres, and / or - comprising fibres made of oxides and / or arranged in the form of a woven fabric, and / or - comprises a matrix consisting of more than 90% by weight of oxides, and / or -Including Al 2 O 3 and / or SiO 2 and / or ZrO 2 and / or Cr 2 O 3 of the matrix, and / or - has a value greater than 1.0 g / cm 3 And less than 2g / cm 3 The bulk density, and / or - having a total SiO content greater than 80% by weight based on oxides 2 +Al 2 O 3 +ZrO 2 +Cr 2 O 3 Proportion.

19. A method as claimed in any one of the preceding claims, comprising: Prior to step a), the following steps are performed: - if the area to be repaired is at least partially defined by a surface of a trough of the furnace in contact with a bath of molten glass, at least partially draining the molten glass from the trough in order to expose the area to be repaired; And, after step b), the following steps: - introducing the glass composition to be melted into the tank, During all the steps of the method, the temperature of the furnace is maintained in the area to be repaired.

20. The method according to any one of claims 1 to 17, wherein the method include: Prior to step a), the following steps are performed: 1) if the area to be repaired is at least partially defined by a surface of a tank of the furnace in contact with a molten glass bath, at least partially draining the molten glass from the tank to expose the area to be repaired; 3) lowering the temperature in the furnace to a temperature above 300° C.; And, after step b), the following steps: 5) increasing and maintaining the temperature of the furnace between 900° C. and 1400° C. to sinter the repaired product; 6) Introducing a glass composition to be melted into the tank, and raising the temperature of the furnace to an operating temperature that causes the composition to melt.

21. The method according to the immediately preceding claim, in, In step 3), the temperature in the furnace is lowered to a temperature higher than 900°C and lower than 1500°C.

22. A method as claimed in any one of the three immediately preceding claims, comprising, after exposing the area to be repaired, the step of rinsing the area to be repaired.

23. A method as claimed in any one of the preceding claims, in, The internal formwork comprises panels made of CMC connected to each other by at least one hinge made of CMC.

24. A method as claimed in any one of the preceding claims, in, More than 50% of the formwork elements by number have a weight greater than 3 kg and less than 50 kg, and / or wherein, More than 30% by number of the formwork elements have a maximum dimension greater than 400 mm and less than 1600 mm.

25. A glass melting furnace comprising at least one zone repaired by the method of any preceding claim.

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