Method for repairing a glass furnace

Abstract

The present invention relates to a method for repairing a wall of a tank (10) of a glass furnace, the method comprising: - solidifying at least part of the glass (50) contained in the tank, - removing the damaged part (11, 12) of the wall as far as the solidified glass (51), - placing a formwork (30, 40, 41, 42) delimiting a cavity (20), the formwork (30, 40, 41, 42) comprising at least an external part (30), the cavity (20) being delimited internally, at least in a lower portion (55), by an exposed face (53) of the solidified glass (51), - pouring an unshaped material (21) into the cavity (20), - solidifying the unshaped material, - returning the solidified glass (51) to the molten state.

Description

[0001] METHOD FOR REPAIRING A GLASS FURNACE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method for repairing a tank of a glass furnace.

[0004] STATE OF THE ART

[0005] A glass furnace comprises a tank for containing molten glass. As illustrated in Figure 1, the tank comprises a substantially vertical side wall and a floor 90 defining a substantially horizontal bottom. The side wall is typically made up of lateral tank blocks 10 forming a bottom belt. The tank blocks 10 extend over the entire height of the tank up to an upper edge.

[0006] The molten glass 50 contained in the vessel is very corrosive and causes significant wear of the vessel. In the case of a gas furnace, with reference to Figure 2, wear is often greatest in an area close to the surface 58 of the molten glass due to the higher temperature. Contact with air above the surface 58 of the glass 50 accelerates corrosion in the vessel blocks close to the surface of the molten glass. Other types of furnaces, for example electric melting furnaces, may have other different wear profiles with a maximum wear point located lower on the height of the vessel.

[0007] To increase the lifespan of a glass furnace, it is necessary to repair the side wall to prevent molten glass from leaking. The goal is to carry out the repairs without emptying and cooling the furnace.

[0008] Typically, with reference to Figure 2, one or more platings are carried out, i.e. the addition of a thickness of plating blocks 11 made of a refractory material to the outside of the tank to restore the thickness of the tank. However, the number of successive platings on a tank is limited by the space available around the furnace. In addition, with reference to Figure 3, corrosion continues to progress further in the area close to the surface, and the wear profile becomes increasingly inhomogeneous over the height of the tank.

[0009] In order to repair the oven by restoring the original dimensions of the tank, several repair techniques can be used.

[0010] In some cases, the tank is partially emptied to lower the level of molten glass. This allows one or more layers of veneer blocks to be replaced in an upper portion of the wall. However, this technique cannot compensate for wear in the lower areas of the tank wall. In other cases, the glass is kept in the tank and cooled in a repair area. The damaged blocks and some of the solidified glass are then removed. New prefabricated blocks are inserted to form a replacement wall, close to the position of the original tank wall.

[0011] Alternatively, the molten glass is completely drained from the tank and the furnace is shut down after emptying. The damaged portion of the blocks is removed and an unshaped material such as liquid concrete is applied to form a replacement wall internally. This technique is known as "cast-in-place." To carry out such casting, a formwork consisting of an outer formwork and an inner formwork is used.

[0012] However, steps such as emptying and / or cooling the tank and subsequent filling and / or reheating are lengthy procedures that result in a prolonged shutdown of the glass furnace.

[0013] STATEMENT OF THE INVENTION

[0014] An aim of the invention is to provide a method for repairing a glass furnace tank that can be implemented without emptying the furnace and that allows great flexibility for adjustments in situ or just before the repair, without requiring the prior manufacture of specific blocks. The repair must also be able to be carried out while minimizing the impact on the quality of the glass.

[0015] To this end, the invention proposes a method for repairing a wall of a tank of a glass furnace containing molten glass, comprising:

[0016] • the solidification of at least part of the glass contained in the tank in contact with a damaged part of the wall of the tank,

[0017] • removal of the damaged part of the tank wall down to the solidified glass,

[0018] • the installation of a formwork delimiting, with the solidified glass, an imprint of the part of the wall to be replaced, said formwork comprising at least one external part, the imprint being delimited internally, at least in a lower portion, by an exposed face of the solidified glass,

[0019] • pouring unshaped material into the impression,

[0020] • solidification of the unshaped material, return of the solidified glass to the molten state.

[0021] The method may further comprise, after casting the unshaped material, placing an upper block of refractory material on the unshaped material. The formwork may further comprise an inner portion extending into a region of the free surface of the glass such that the impression is delimited, in an upper portion, by the inner portion of the formwork.

[0022] The use of unshaped material and the use of solidified glass to delimit the lower part of the impression allows for great adaptability of the geometry during the process. Such a process also allows the preservation of undamaged parts of the furnace.

[0023] In some embodiments, the inner portion of the formwork comprises a refractory material adapted to form, with the unformed material, a portion of the repaired wall of the vessel.

[0024] Advantageously, the internal part of the formwork comprises chromium oxide, alumina-zirconia-silica, alumina or zirconia.

[0025] Advantageously, the internal part of the formwork comprises an inserted block of refractory material held by a holding system, the method further comprising removing the holding system after pouring the unshaped material.

[0026] In other embodiments, the internal portion of the formwork comprises a vitreous silica plate or a glass plate or a fiberglass plate.

[0027] Preferably, the inner portion of the formwork is removable, the method further comprising removing the inner portion of the formwork after casting the unshaped material into the impression. Removing the inner portion of the formwork prevents said formwork from being absorbed by the molten glass and thus prevents the introduction of impurities into the glass.

[0028] In other embodiments, the internal portion of the formwork comprises a metal frame.

[0029] Advantageously, the method further comprises cooling the internal part of the formwork.

[0030] Preferably, the exposed surface of the glass has a temperature between 50°C and 300°C.

[0031] Advantageously, the unshaped material is a phosphatic setting material, a colloidal setting material or a sodium silicate setting material.

[0032] In some embodiments, a lower portion of the imprint is delimited by a residue of the tank wall to be repaired.

[0033] Advantageously, removal of the damaged portion of the tank includes removal of a portion of the solidified glass.

[0034] In some embodiments, the method further comprises embedding at least one wear sensor into the unshaped material. Embedding the wear sensors and / or tracers allows monitoring of corrosion progress to plan future repairs of the same tank.

[0035] BRIEF DESCRIPTION OF THE FIGURES

[0036] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:

[0037] Figure 1 is a sectional view of a side wall and a portion of the bottom of a glass furnace in contact with molten glass.

[0038] Figure 2 illustrates the sidewall corrosion of Figure 1 and a plating repair.

[0039] Figure 3 illustrates advanced corrosion of the sidewall of the wall in Figure 2.

[0040] Figure 4 illustrates advanced corrosion of a side wall and a repair area by a method according to the invention.

[0041] Figure 5 illustrates a first step of repair by a method according to the invention.

[0042] Figure 6 illustrates a second repair step using a method according to the invention.

[0043] Figure 7A illustrates a third repair step by a method according to the invention using an inserted block.

[0044] Figure 7B illustrates the third step of residue-free repair of a block of the initial wall.

[0045] Figure 7C illustrates the third repair step using a push bar.

[0046] Figure 7D illustrates the third embodiment with a wide inserted block.

[0047] Figure 7E is a sectional view of an inserted block.

[0048] Figure 7F illustrates one embodiment of the third repair step using an inserted plate.

[0049] Figure 7G illustrates an embodiment of the third repair step using a removable internal formwork portion.

[0050] Figure 7H illustrates an embodiment of the third repair stage with external formwork up to an intermediate height.

[0051] Figure 8 illustrates a fourth repair step using a method according to the invention.

[0052] Figure 9A illustrates a fifth repair step using an inserted block.

[0053] Figure 9B illustrates a fifth repair step using an inserted plate. Figure 9C illustrates a fifth repair step using a removable internal formwork portion.

[0054] Figure 9D illustrates a fifth repair step in which a block of refractory material is placed on top of the unshaped material.

[0055] Figure 10 illustrates an embodiment comprising the embedding of several wear sensors.

[0056] DETAILED DESCRIPTION OF EMBODIMENTS

[0057] In this text, the terms "inner" and "outer", "internal" and "external" are understood in relation to the central part of the tank containing molten glass. An "inner" wall is to be understood as facing the molten glass (towards the right in Figures 1 to 10), and an "outer" wall is facing the outside of the tank (towards the left in Figures 1 to 10). The wall thickness and the width of the cavity and the formwork extend between the inner edge and the outer edge of the respective element.

[0058] Figure 4 illustrates a side wall of a vessel to be repaired. The vessel contains molten glass 51. The side wall of the vessel includes starting blocks 10 used for the manufacture or a previous repair of the vessel, and may include one or more plating blocks 11 added later. The side wall initially extended to a position Pi at which the molten glass was delimited. During use of the furnace, the starting blocks 10 and, if applicable, the plating blocks 11 were broken down in a corrosion zone 59. The corrosion zone 59 is therefore also filled with molten glass.

[0059] In order to carry out a repair, the glass is locally cooled to a repair temperature TR in a cooling zone Z in contact with the area to be repaired. Such cooling of the glass makes it possible to solidify the glass locally and to avoid emptying the furnace. The cooling is carried out using a cooling means 60 allowing the temperature of the glass to be lowered in a zone ZR around said cooling means 60. The cooling system 60 is typically immersed in the molten glass from the free face 58 of the glass, for example through openings in the superstructure of the furnace. The free face is understood to mean the upper face of the solidified or molten glass.

[0060] Such a cooling system may be in the form of an elongated tube, open or closed at its lower end. A circuit of a cooling fluid is arranged inside the tube. The cooling fluid may be cold water which is conveyed to the circuit from outside the tank. The cooling means 60 is inserted into the furnace near the area to be repaired, and typically does not penetrate to the bottom of the furnace. In certain cases, in particular for a large area of ​​the area to be repaired, several cooling means 60 are used simultaneously. A person skilled in the art will know how to size the cooling means 60 and adjust the extent of the cooling zone ZR according to the geometry of the tank and the repair to be carried out. This avoids cooling all of the glass present in the tank.

[0061] The repair temperature TR is lower than the glass transition temperature TG of the glass, i.e. the temperature at which the cooled glass has a viscosity greater than 10 12 Pa.s and is therefore in a solid state. The repair temperature TR can be chosen lower than the glass transition temperature TG to allow an operator to access an area near the furnace to carry out manipulations on the wall. For example, molten glass at an initial temperature of approximately 1500°C can be locally cooled to a repair temperature TR of approximately 300°C to solidify the glass. The cooling zone ZR in which the glass is solidified extends, for example, within a radius of between 1 and 3 m around the cooling means. The cooling means is maintained in the tank in order to cool the glass continuously to the repair temperature TR.

[0062] After cooling the glass, with reference to Figure 5, at least part of the damaged starting blocks 10 and / or plating blocks 11 and at least part of the cooled glass are removed. The removal is carried out in a removal zone 52 extending to an interior position PR of the tank which will delimit the internal wall after the repair.

[0063] In some embodiments, only a first portion 11 is removed,

[0064] 12 of the wall blocks in an area of ​​the top of the tank, and a first portion 52 of the molten glass having filled the corrosion area. For example, any plating blocks 11 and a first portion 12 of the initial wall having already undergone significant corrosion are removed, typically in the upper part of the initial wall. Simultaneously, a first portion 52 of the glass is removed near the edge of the tank and in contact with the first portion 11, 12 of the wall blocks.

[0065] A second portion 13 of the blocks, typically near the bottom of the tank, and / or a second portion 51' of the cooled glass is retained in its position. Such a second portion 13 has typically undergone less corrosion and / or transformation and remains sufficiently strong for further use. The second portion 13 of the blocks will be used as the bottom of a new wall of the tank. Retaining a portion

[0066] 13 of the blocks makes it possible to avoid shrinkage close to the bottom of the tank, which is difficult to access and in which the cooling of the glass is often less effective. This approach also makes it possible to avoid cooling in depth of the tank. In certain cases, said portion 13 is shaped by mechanical tools in order to adjust its geometry for the fixing of a formwork, and / or according to the casting properties of the unshaped material. The surface of the portion 13 can also be structured to facilitate the adhesion of the material forming the replacement wall.

[0067] The PR position of the inner face after the repair can be shifted towards the outside of the tank compared to the Pi position of the initial inner face.

[0068] In other embodiments, all damaged blocks and solidified glass are removed up to the initial inner face position Pi, so that the position PR of the inner face after repair is identical to the initial position Pi.

[0069] Removal of the damaged starter blocks 10 and / or plating blocks 11 may be carried out by tools known for attacking refractory material, for example by an air hammer or a diamond chain saw.

[0070] After removal, with reference to Figure 6, the cooled glass has an exposed outer face 53 corresponding to the position PR of the inner face of the tank after repair.

[0071] A formwork is then installed to prepare an impression. The formwork includes an external part and may also include an internal part. The impression will then be filled with an unformed material to form a new wall of the tank.

[0072] With reference to Figure 7A, the imprint 20 is delimited, on its outer side, by the external part 30 of the formwork. The external part 30 of the formwork is typically a plate made of metal, wood, or a refractory material. By refractory material, we mean a material having a melting temperature greater than 1500°C. Said plate extends vertically between the residue 13 of the starting block and / or plating block and the upper limit of the replacement wall to be formed. Alternatively, the external part of the formwork is one or more plating blocks extending over the height of the tank, for example a plating block with a thickness of between 75 mm and 120 mm. To prepare the imprint, the external part 30 of the formwork is fixed to the preserved portion 13 of the starting block and / or the plating block.

[0073] On its lower side, the imprint 20 may be delimited by the preserved portion 13 of a starting block and / or a plating block. Alternatively, the imprint may be delimited on its lower side by the sole 90 of the furnace.

[0074] On its inner side, the imprint is at least partially delimited by a lower portion 55 of the exposed face 53 of the cooled glass. Optionally, an inner portion of the formwork may be placed only on an upper portion 54 of the outer face of the cooled glass. The inner portion of the formwork is separate and distinct from the outer portion 30 of the formwork. Figures 7A to 7F illustrate several embodiments of an imprint formed by an inner portion of formwork disposed on an upper portion 54 of the exposed face of the cooled glass, and a lower portion 55 of the exposed face of cooled glass. In other embodiments, as illustrated in Figure 7H, the imprint is formed only by a lower portion 55 of the exposed face of cooled glass.

[0075] In a first embodiment, with reference to Figure 7A, the internal part of the formwork is in the form of an inserted block 40 made of a refractory material. The refractory material of the inserted block 40 is compatible with the molten glass which will be in contact with the wall after the repair, that is to say it considerably limits the creation of defects, the contamination of the glass and the formation of bubbles which can hinder the implementation of the glass. In an illustrative and non-limiting manner, such an inserted block 40 can be made of chromium oxide, electrofused or agglomerated alumina-zirconia-silica (AZS), electrofused or agglomerated alumina, or mullite-zirconia.

[0076] The inserted block 40 is kept in this position after the tank has been repaired. The inserted block 40 therefore forms, with the material used for filling the impression, the new wall of the tank.

[0077] During the filling of the impression, the inserted block 40 is held on the upper part 54 of the exposed face 53 of the solidified glass by one or more holding systems. Typically, the holding system is chosen according to the dimensions of the inserted block 40 and the geometry of the impression. A holding system may comprise a bar 80 fixed on an upper face and / or on an external face of the inserted block 40. Such a bar 80 is typically removable and can be removed at the end of the repair process. For example, each bar can be inserted into a bore arranged on an upper or external face of the inserted block 40.

[0078] In a variant, with reference to Figure 7B, no portion 13 of the wall blocks has been retained. One or more joint covers 94 may be exposed between the side wall of the glass 55 and the base 90.

[0079] The external part 30 of the formwork is fixed on the belt 95 of the furnace and on one or more fixing sub-layers 92, 93 below the sole 90 of the furnace. Other sub-layers 91 can be arranged between the sole 90, the belt 95 and the fixing sub-layers 92, 93.

[0080] The presence of a portion of the blocks 13 of the wall and the fixing of the external part 30 of the formwork are independent of the type of internal formwork. Thus, fixing of an external part 30 of the formwork can also be applied to the embodiments of the internal part of the formwork illustrated in Figures 7B and 7C. Alternatively, with reference to Figure 7C, the inserted block can be held by a push bar 81 which is pressed against the inserted block 40 in the direction of the exposed face 53 of the glass without a fixing system on the inserted block 40.

[0081] In some cases, as illustrated in Figure 7D, the push bar 82 extends through the outer portion 30 of the formwork. In this case, the outer portion 30 of the formwork is provided with an opening 85 forming a passage for the push bar 82. In other cases (not illustrated), the push bar extends outwardly above the upper edge of the outer portion of the formwork. In some embodiments, a primary or additional holding system may be arranged at the underside of the block.

[0082] In some embodiments, with reference to Figures 7A to 7C, the thickness D of the inserted block 40 is less than the thickness of the impression. In other embodiments, with reference to Figure 7D, the thickness D of the inserted block 40 corresponds to the thickness of the wall to be formed.

[0083] With reference to Figure 7E, the inserted block 40 typically has a trapezoidal section. The upper face 40S of the inserted block is intended to partially or entirely form the upper face of the replacement wall of the tank. Typically, said upper face 40S of the inserted block is aligned with the initial height of the tank.

[0084] The inner face 40I of the inserted block 40 extends along the upper portion 54 of the exposed face 53 of the cooled glass and, in the upward extension of said exposed face 53, beyond said exposed face. The inner face 40I typically extends by a height Hs of at least 75 to 100 mm below the free face 58 of the glass. The inner face 40I of the inserted block is typically smooth and adapted to establish good mechanical contact with the exposed face 53 of the cooled glass.

[0085] The outer face 40E of the inserted block may extend parallel to the inner face 40I or obliquely. When the outer face 40E is intended to be covered during filling of the impression, it may have a texture facilitating the adhesion of the material used for filling, for example holes or grooves. When the width D of the inserted block corresponds to the width of the impression, the outer face 40E of the inserted block is intended to form a part of the outer wall of the tank. In this case, the outer face 40E is typically smooth.

[0086] The lower face 40B of the inserted block 40 is preferably oblique, so that the height Hi of the inner face of the inserted block 40 is greater than the height HE of the outer face of the inserted block 40.

[0087] The oblique orientation of the lower face 40B of the inserted block 40 allows air to escape during the filling of the impression to evacuate the air contained in the impression and also air coming from air bubbles present in the material used for the filling. This avoids creating areas of porosity in the replacement wall.

[0088] Another advantage of the oblique orientation of the lower face 40B is the possibility of using the oblique interface between the inserted block and the material filling the impression for wall wear measurements at a later stage. For example, said interface can be detected by radar-type measurements. From the information on the geometry and position of the inserted block, the corrosion of the inserted block and the interface can be determined, and thus anticipate the moment when a new wall repair must be carried out.

[0089] Preferably, the lower face of the lower face 40B of the inserted block has a roughness promoting the adhesion of the material used for filling the impression. For example, the lower face of the inserted block may have a texture such as grooves or adhesion holes.

[0090] In another embodiment, with reference to Figure 7F, the internal part 40 of the formwork is an inserted plate 41 extending parallel to the exposed face 53 of the cooled glass and covering only an upper portion 54 of said exposed face 53. Such an inserted plate 41 may be made of vitreous silica, glass or glass fibers. The inserted plate 41 may be provided with a holding system as described above, or be fixed directly to the exposed face 53 of the cooled glass. Preferably, the inserted plate 41 has a thickness greater than 3 mm.

[0091] Like the inserted block described above, the plate is retained in the replacement wall after the repair. Thus, the plate 41 forms, with the material used for filling the impression, a new wall of the tank.

[0092] The upper edge of the inserted plate 41 is intended to form a portion of the upper edge of the replacement wall of the tank. Typically, the upper edge of the plate 41 is aligned with the initial height of the tank. The plate 41 typically extends by a height Hs of at least 75 to 100 mm below the free face 58 of the glass.

[0093] In a third embodiment, with reference to FIG. 7G, the internal portion of the formwork 42 is removable, allowing removal after filling the cavity. An internal portion of the removable formwork 42 is typically made of metal. Such an internal portion of the formwork 42 may be cooled entirely or partially, for example by one or more flows of cold water circulating inside the internal portion of the formwork 42.

[0094] Typically, the inner portion of the removable formwork 42 comprises a substantially vertical plate 44 extending parallel to the exposed face 53 of the cooled glass, and a substantially horizontal plate 43 secured to the substantially vertical plate 44. The substantially vertical plate 44 extends along the upper portion 54 of the exposed surface 53 of the cooled glass and projects above the replacement wall to be manufactured. In an illustrative and non-limiting manner, the vertical plate 44 extends to a height of between 5 and 25 cm above the free face of the cooled glass. The substantially horizontal plate 43 covers the footprint above the portion of the tank to be replaced. The inner portion of the formwork is typically held in place at the horizontal plate 43.

[0095] For the various embodiments described above, the internal formwork is applied only to the upper portion 54 of the exposed face 53 of the glass. A lower portion 55 of the exposed face 53 of the glass is directly used to delimit the imprint and does not include any internal formwork.

[0096] In another embodiment, illustrated in Figure 7H, the imprint for the unshaped material extends only over a lower portion 55 of the glass wall up to an intermediate height Hi. In some cases, the formwork does not include any interior portion on the upper portion of the exposed face 54 of the glass. On its interior side, the imprint is therefore formed only by the glass wall. In this embodiment, the external portion of the formwork typically extends up to an intermediate height Hi, less than the height H p of the replacement wall to be made.

[0097] In other embodiments, not shown, the formwork comprises an inner portion disposed on an upper portion 54 of the glass wall up to an intermediate height, and an outer portion of the formwork extending up to the same intermediate height.

[0098] After the installation of the external part and, where appropriate, the internal part of the formwork, with reference to Figure 8, the impression 20 is filled with an unshaped material 21. By an unshaped material is meant a mixture of particles and liquid capable of flowing so as to fill the impression.

[0099] Said unshaped material is suitable for forming a refractory material after curing. Preferably, the unshaped material is a hot-setting material capable of withstanding rapid evaporation of the liquid contained in the mixture, for example a material comprising a mixture of sintered or electrofused grains of AZS, sintered or electrofused grains of mullite-zirconia, electrofused tabular alumina or alpha-beta alumina grains, grains of zirconia, silica and / or chromium oxide, or mixtures thereof.

[0100] Advantageously, the unshaped material is a colloidal or phosphatic setting material or a sodium silicate setting material. Such materials provide very good mechanical strength when casting and solidification are carried out at high temperatures, for example above 300°C. Colloidal setting products are prepared with a liquid binder of colloidal silica type. Evaporation of the water contained in the binder causes a silicic type frost setting. Such a material is for example sold by Magneco Metrel under the name "Metpump AZS". Phosphatic setting products contain phosphatic acid and form, during the solidification reaction, alumina phosphate which has high corrosion resistance, very good mechanical strength above 350°C, and very good resistance to thermal shock.Such materials are, for example, marketed by the company DSF under the name Duropave 95 Mortar, and by the company RHI under the name RESISTIT “ZM 260”.

[0101] Alternatively, the unshaped material may be a hydraulically setting material such as a cement, for example an aluminous refractory cement.

[0102] In the case of an internal formwork part in the form of an inserted block, the choice of unformed material is adapted to the material of the inserted block. This optimizes the adhesion between the unformed material and the block, and minimizes corrosion during use of the furnace.

[0103] A combination of these materials can also be chosen to optimize corrosion resistance and, in some cases, detection of the interface between the inserted block and the refractory material from the unshaped material. This is particularly interesting for carrying out wear analysis via radar detection of the interface.

[0104] Table 1 below illustrates several preferred combinations of bases for refractory materials.

[0105] The impression is filled with the unshaped material up to a height HP of the replacement wall or an intermediate height Hj. Typically the unshaped material is poured into the impression by means of a pump.

[0106] When the thickness D of the inserted block 40 corresponds to the width of the imprint, as illustrated in Figure 7E, the filling is typically carried out by a chute 48 passing through the external part 30 of the formwork. In other cases, the filling can be carried out by the opening at the top of the imprint. When the external formwork extends to an intermediate height Hi, less than the height H p of the replacement wall to be made, the unshaped material is poured up to the intermediate height Hj. In this case, an upper block 46 made of a refractory material is placed above the unshaped material after casting, to form an upper portion of the replacement wall. The upper block is prefabricated and can be made of one of the materials indicated for the block inserted in the table above.

[0107] Such an upper block can in particular be used when the formwork does not include any interior part. With reference to figure 9D, the height of the upper block 46 corresponds to the difference between the intermediate height Hj and the height of the wall H p of the replacement wall. The thickness of the top block corresponds to the desired thickness of the replacement wall.

[0108] Before casting, the unshaped material has a temperature close to room temperature, i.e. typically between 15°C and 30°C. When the unshaped material comes into contact with the wall of the cooled glass, its temperature increases rapidly up to the repair temperature TR of the glass which is typically between 50°C and 500°C, for example between 300°C and 350°C or between 50°C and 300°C. This increase in temperature causes evaporation of the free water from the mixture, the viscosity of which increases until the solidification stage of the material according to the phenomenon of colloidal setting. Setting can also be carried out at a higher temperature by phosphatic setting before the actual ceramization of the material.

[0109] After a solidification time which is typically between 5 and 180 minutes, the setting of the unshaped material is completed throughout the entire volume.

[0110] After the unshaped product has set, the retaining system for the internal part of the formwork, or, in the case of a removable internal part of the formwork, the internal part of the formwork, is removed, if necessary. In this embodiment, removing the internal part of the formwork 42 in contact with the glass prevents any contamination and / or formation of bubbles in the glass.

[0111] Cooling of the glass is stopped, for example by removing the cooling device 60. This causes a gradual rise in the temperature of the glass, resulting in melting of the glass 50. The unshaped material solidified in the impression is heated by the glass 50 to a temperature close to the temperature of the molten glass. This heating causes sintering of the unshaped material, increasing its mechanical strength and corrosion resistance.

[0112] In the case of a non-removable internal formwork portion, such as an inserted plate or block, with reference to Figures 9A and 9B, the solidified unshaped material forms a replacement wall with the internal formwork portion. In the case of a removable internal formwork portion, with reference to Figure 9C, the entire exposed face 53 of the glass is in direct contact with the unshaped material 21. The unshaped material forms a wall delimiting the glass over the entire height of the replacement wall.

[0113] In the case where the unshaped material is cast only up to an intermediate height, the exposed face of the glass is in direct contact with the unshaped material up to said intermediate height. With reference to Figure 9D, the solidified unshaped material forms a replacement wall with an upper block 46.

[0114] The use of unshaped material allows the replacement wall to be adapted to the geometry of the impression, allowing the repair to be adjusted to the conditions on site during the repair with great flexibility.

[0115] The shape of the replacement wall, adjusted to the geometry of the cooled glass, also allows for uniform heating of the unformed material in contact with the glass. In addition, the use of unformed material facilitates the transport of the replacement wall because this method does not require the transport and installation of preformed blocks, which are typically heavy and fragile.

[0116] After solidification and / or sintering of the unformed material, the outer part of the formwork can be removed. In some cases, particularly when the outer part of the formwork is a veneer block, the outer part of the formwork is retained on the outside of the replacement wall during use of the furnace.

[0117] In some embodiments, with reference to FIG. 10, one or more wear sensors 70 are embedded in the replacement wall. Such a wear sensor is, for example, a loop of electrically conductive wire whose ends can be connected to an electricity source outside the tank. Alternatively, the sensor may be a system comprising one or more thermocouples.

[0118] Typically, the sensors are installed at different heights and / or distances from the outer wall of the cavity before the unformed material is poured. The location of each sensor is chosen based on the expected corrosion of the replacement wall. The cavity is then filled with the unformed material. In this step, the sensors are embedded in the wall.

[0119] During use of the repaired furnace, the replacement wall is subjected to corrosion and the outer face of the molten glass approaches the sensor locations. Thus, the sensors successively reach a limit operating temperature and then come into contact with the molten glass. As the corrosion zone approaches the sensor, the temperature near the sensor rises, which can be detected by a thermocouple type sensor. As the corrosion progresses further, the sensors are destroyed by the increase in temperature and possibly by the corrosiveness of the glass. When a wire is destroyed, an electric current passing through the wire is interrupted. In this way, it is possible to determine the progress of corrosion at the location of each sensor and to determine the progress of corrosion of the entire wall by extrapolation.Depending on the positioning of the sensors, information can be obtained on the wear profile along the width and height of the wall. This information makes it possible to anticipate future repairs to the wall and prevent the risk of molten glass leaks.

[0120] Such wear detection systems can be used immediately after the repair process is complete.

Claims

CLAIMS 1. Method for repairing a wall of a tank (10) of a glass furnace containing molten glass, comprising: • the solidification of at least part of the glass (50) contained in the tank in contact with a damaged part (11, 12) of the wall of the tank, • removal of the damaged part (11, 12) from the wall of the tank down to the solidified glass (51), • the installation of a formwork (30, 40, 41, 42) delimiting, with the solidified glass (51), an imprint (20) of the part of the wall to be replaced, said formwork (30, 40, 41, 42) comprising at least one external part (30), the imprint (20) being delimited internally, at least in a lower portion (55), by an exposed face (53) of the solidified glass (51), • pouring an unshaped material (21) into the impression (20), • solidification of the unshaped material, • the return of the solidified glass (51) to the molten state.

2. The method of claim 1, further comprising, after casting the unshaped material (21), placing an upper block (46) of refractory material on the unshaped material (21).

3. Method according to claim 1 or claim 2 in which the formwork further comprises an internal part (40, 41, 42) extending in a region of the free surface (58) of the glass (51) so that the imprint (20) is delimited, in an upper portion, by the internal part of the formwork (40, 41, 42).

4. Method according to claim 3 in which the internal part (40) of the formwork comprises a refractory material adapted to form, with the unshaped material, a part of the repaired wall of the tank.

5. The method of claim 4 wherein the internal portion of the formwork comprises chromium oxide, alumina-zirconia-silica, alumina or zirconia.

6. A method according to claim 4 or claim 5, wherein the internal part (40) of the formwork comprises an inserted block (40) of refractory material held by a holding system (80, 81, 82), the method further comprising removing the holding system (80, 81, 82) after casting the unshaped material.

7. Method according to claim 3, in which the internal part (41) of the formwork comprises a vitreous silica plate or a glass plate or a glass fiber plate.

8. The method of claim 3, wherein the inner portion (42) of the formwork is removable, the method further comprising removing the inner portion of the formwork after casting the unshaped material (21) into the impression (20).

9. Method according to claim 8, in which the internal part (42) of the formwork comprises a metal frame.

10. A method according to claim 8 or claim 9, further comprising cooling the internal portion (42) of the formwork.

11. A method according to any preceding claim, wherein the exposed surface of the glass (53) has a temperature between 50°C and 300°C.

12. A method according to any preceding claim, wherein the unshaped material (21) is a phosphatic setting, colloidal setting or sodium silicate setting material.

13. Method according to any one of the preceding claims, in which a lower part of the imprint (20) is delimited by a residue (13) of the tank wall to be repaired.

14. A method according to any preceding claim, wherein removing the damaged portion (10, 11) from the vessel comprises removing a portion (52) of the solidified glass.

15. A method according to any preceding claim, further comprising embedding at least one wear sensor (70) in the unshaped material

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