Glass furnace repair procedure

Abstract

The present invention relates to a method for repairing a wall of a glass furnace tank (10), comprising: solidifying at least a portion of the glass (50) contained in the tank, removing the damaged portion (11, 12) of the wall down to the solidified glass (51), installing a formwork (30, 40, 41, 42) defining an cavity (20), said formwork (30, 40, 41, 42) comprising an external portion (30) and an internal portion (40, 41, 42) such that the cavity (20) is internally delimited, in an upper portion (54), by the internal portion of the formwork (40, 41, 42) and, in a lower portion (55), by an exposed face (53) of the solidified glass (51), pouring an unshaped material (21) into the cavity (20), solidification of the unshaped material, return of the solidified glass (51) to the molten state. Figure for the abbreviation: Fig 8

Description

Title of the invention: Method for repairing a glass furnace technical field

[0001] The present invention relates to a method for repairing a glass furnace tank. State of the art

[0002] A glass furnace includes a tank for holding molten glass. As illustrated in [Fig. 1], the tank comprises a predominantly vertical side wall and a hearth 90 defining a predominantly horizontal bottom. The side wall is typically made up of lateral tank blocks 10 forming a bottom band. The tank blocks 10 extend the full height of the tank up to an upper edge.

[0003] The molten glass 50 contained in the vessel is highly corrosive and causes significant wear on the vessel. In the case of a gas furnace, as shown in [Fig. 2], wear is often more pronounced in an area close to the surface 58 of the molten glass due to the higher temperature. Contact with the air above the surface 58 of the glass 50 accelerates corrosion in the vessel blocks near the surface of the molten glass. Other types of furnaces, for example, electric melting furnaces, may exhibit different wear profiles with a maximum wear point located lower along the height of the vessel.

[0004] In order to increase the service life of a glass furnace, it is necessary to carry out repairs to the side wall to prevent leaks of molten glass. The aim is to carry out the repairs without emptying and cooling the furnace.

[0005] Typically, with reference to [Fig. 2], one or more re-claddings are carried out, that is, the addition of a layer of refractory material re-cladding blocks 11 to the outside of the vessel to restore the vessel's thickness. However, the number of successive re-claddings on a vessel is limited by the available space around the furnace. Moreover, with reference to [Fig. 3], corrosion continues to progress further in the area near the surface, and the wear profile becomes increasingly uneven along the height of the vessel.

[0006] In order to repair the oven by restoring the original dimensions of the tank, several repair techniques can be used.

[0007] In some cases, the tank is partially emptied to lower the level of the molten glass. This allows one or more layers of plating 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.

[0008] 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.

[0009] Alternatively, the molten glass is completely drained from the furnace, and the furnace is shut down after draining. The damaged portion of the blocks is removed, and an unshaped material such as liquid concrete is applied to form an internal replacement wall. This technique is known as "cast-in-place." To perform such a casting, a formwork consisting of an outer and an inner formwork is used.

[0010] However, steps such as draining and / or cooling the tank and subsequent refilling and / or reheating are lengthy procedures which result in a prolonged shutdown of the glass furnace. Description of the invention

[0011] One object of the invention is to provide a method for repairing a glass furnace tank that can be carried out without draining the furnace and that allows for great flexibility for adjustments in situ or just before the repair, without requiring the prior manufacture of specific blocks. Furthermore, the repair must be able to be carried out while minimizing the impact on the quality of the glass.

[0012] To this end, the invention proposes a method for repairing a wall of a glass furnace tank containing molten glass, comprising: • the solidification of at least some of the glass contained in the tank in contact with a damaged part of the tank wall, • the removal of the damaged section of the tank wall down to the solidified glass, • the installation of a formwork delimiting, with the solidified glass, an imprint of the part of the wall to be replaced, said formwork comprising an external part and an internal part, the internal part extending into a region of the free surface of the glass so that the imprint is delimited internally, in an upper portion, by the internal part of the formwork and, in a lower portion, by an exposed face of the solidified glass, • the pouring of an unshaped material into the mold, • the solidification of the unshaped material,

[0013] the return of the solidified glass to the molten state.

[0014] The use of an unshaped material and the use of solidified glass to delimit the lower part of the impression allows for a high degree of adaptability of the geometry during the process. Such a process also allows the undamaged parts of the furnace to be preserved.

[0015] In some embodiments, the internal part of the formwork comprises a refractory material adapted to form, with the unshaped material, a part of the repaired wall of the tank.

[0016] Advantageously, the internal part of the casing comprises chromium oxide, alumina-zirconia-silica, alumina or zirconia.

[0017] Advantageously, the internal part of the formwork comprises an inserted block of refractory material held by a retaining system, the method further comprising the removal of the retaining system after the pouring of the unshaped material.

[0018] In other embodiments, the internal part of the formwork comprises a vitreous silica plate or a glass plate or a fiberglass plate.

[0019] Preferably, the inner part of the mold is removable, the method further comprising removing the inner part of the mold after the unshaped material has been poured into the mold cavity. Removing the inner part of the mold prevents the molten glass from absorbing the mold and thus prevents impurities from being introduced into the glass.

[0020] In other embodiments, the internal part of the formwork comprises a metal reinforcement.

[0021] Advantageously, the process further includes cooling the internal part of the formwork.

[0022] Preferably, the exposed surface of the glass has a temperature between 50°C and 300°C.

[0023] Advantageously, the unshaped material is a phosphate setting material, a colloidal setting material or a sodium silicate type setting material.

[0024] In some embodiments, a lower part of the imprint is delimited by a residue of the tank wall to be repaired.

[0025] Advantageously, the removal of the damaged part of the tank includes the removal of a portion of the solidified glass.

[0026] In certain embodiments, the method further comprises embedding at least one wear sensor in the unshaped material. Embedding the wear sensors and / or tracers allows monitoring of corrosion development in order to plan future repairs to the same tank. Brief description of the figures

[0027] Other features and advantages of the invention will become apparent from the detailed description that follows, with reference to the accompanying drawings, in which:

[0028] Fig. 1 is a cross-sectional view of a side wall and a portion of the bottom of a glass furnace in contact with molten glass.

[0029] Fig. 2 illustrates the corrosion of the side wall of Fig. 1 and a repair by plating.

[0030] Fig. 3 illustrates advanced corrosion of the side wall of the wall of Fig. 2.

[0031] Figure 4 illustrates the advanced corrosion of a side wall and a repair area. by a method according to the invention.

[0032] Figure 5 illustrates a first repair step using a method according to the invention.

[0033] Figure 6 illustrates a second repair step using a method according to the invention.

[0034] Figure 7A illustrates a third repair step using a method according to the invention with an inserted block.

[0035] Fig. 7B illustrates the third stage of residue-free repair of a block of the initial wall.

[0036] Fig. 7C illustrates the third repair step using a push bar.

[0037] Fig. 7D illustrates the third embodiment with a wide inserted block.

[0038] Fig. 7E is a cross-sectional view of an inserted block.

[0039] Figure 7F illustrates one embodiment of the third repair step using an inserted plate.

[0040] Fig. 7G illustrates an embodiment of the third repair step using an internal removable formwork part.

[0041] Figure 8 illustrates a fourth repair step by a process according to the invention.

[0042] Fig. 9A illustrates a fifth repair step using an inserted block.

[0043] Figure 9B illustrates a fifth repair step using a plate inserted.

[0044] Fig. 9C illustrates a fifth repair step using an internal removable formwork part.

[0045] Fig. 10 illustrates an embodiment comprising the embedding of several wear sensors. Detailed description of implementation methods

[0046] In this text, the terms "inside" and "outside," "internal" and "external," are understood to refer to the central part of the tank containing molten glass. An "internal" wall is to be understood as facing the molten glass (to the right in Figures 1 to 10), and an "external" wall is oriented towards the outside of the tank (to the left in Figures 1 to 10). The wall thickness and the width of the cavity and the casing extend between the internal and external edges of the respective element.

[0047] Figure 4 illustrates a side wall of a tank to be repaired. The tank contains molten glass 51. The side wall of the tank includes starter blocks 10 used for the manufacture or a previous repair of the tank, and may include one or more plating blocks 11 added subsequently. The side wall initially extended to a position 11 at which the molten glass was contained. During use of the furnace, the starter blocks 10 and, where applicable, the plating blocks 11 were decomposed into a corrosion zone 59. The corrosion zone 59 is therefore also filled with molten glass.

[0048] To perform a repair, the glass is locally cooled to a repair temperature TR in a cooling zone ZR in contact with the area to be repaired. Such cooling of the glass allows the glass to solidify locally and avoids draining the furnace. The cooling is carried out using a cooling means 60 that lowers the temperature of the glass 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 furnace superstructure. The free face is understood to be the upper surface of the solidified or molten glass.

[0049] Such a cooling system may be in the form of an elongated tube, open or closed at its lower end. A cooling fluid circuit is arranged inside the tube. The cooling fluid may be cold water, which is supplied 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 as far as the furnace floor. In some cases, particularly for a large area to be repaired, several cooling means 60 are used simultaneously. Those skilled in the art will be able 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. Cooling all the glass present in the tank is avoided.

[0050] The repair temperature TR is lower than the glass transition temperature TG of the glass, that is, the temperature at which the cooled glass has a viscosity greater than 10¹² 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 perform 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 between 1 and 3 m around the cooling unit. The cooling unit is kept in the tank to continuously cool the glass to the repair temperature TR.

[0051] After the glass has cooled, as shown in [Fig. 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 within a removal zone 52 extending to an internal position PR of the tank, which will define the inner wall after the repair.

[0052] In some embodiments, only a first portion 11, 12 of the wall blocks in an area at the top of the tank and a first portion 52 of the molten glass that has filled the corrosion zone are removed. For example, any plating blocks 11 and a first portion 12 of the initial wall that has already undergone significant corrosion, typically in the upper part of the initial wall, are removed. Simultaneously, a first portion 52 of the glass near the edge of the tank and in contact with the first portion 11, 12 of the wall blocks is removed.

[0053] 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 base of a new tank wall. Retaining a portion 13 of the blocks avoids shrinkage near the bottom of the tank, which is difficult to access and where glass cooling is often less efficient. This approach also avoids deep cooling of the tank. In some cases, said portion 13 is shaped by mechanical tools to adjust its geometry for attaching a mold, and / or according to the casting properties of the unshaped material.The surface of portion 13 can also be structured to facilitate the adhesion of the material forming the replacement wall.

[0054] The PR position of the inner face after the repair can be shifted towards the outside of the tank relative to the initial position ?! of the inner face.

[0055] In other embodiments, all the damaged blocks and solidified glass are removed down to the initial position of the inner face Pb so that the position PR of the inner face after repair is identical to the initial position Pb

[0056] The removal of the damaged starting blocks 10 and / or plating blocks 11 can be carried out by tools known to attack a refractory material, for example by a pneumatic hammer or a diamond chain saw.

[0057] After removal, with reference to [Fig.6], the cooled glass has an exposed outer face 53 corresponding to the PR position of the inner face of the tank after the repair.

[0058] A mold comprising an external part and an internal part is then placed to prepare an impression. This impression will subsequently be filled with an unshaped material to form a new wall of the tank.

[0059] With reference to [Fig. 7A], the cavity 20 is delimited, on its outer side, by the external portion 30 of the formwork. The external portion 30 of the formwork is typically a plate made of metal, wood, or a refractory material. By refractory material is meant a material having a melting point above 1500°C. This plate extends vertically between the residue 13 of the starting block and / or lining block and the upper limit of the replacement wall to be formed. Alternatively, the external portion of the formwork is one or more lining blocks extending over the height of the tank, for example, a lining block with a thickness between 75 mm and 120 mm. For the preparation of the cavity, the external portion 30 of the formwork is fixed to the retained portion 13 of the starting block and / or the lining block.

[0060] On its lower side, the cavity 20 can be delimited by the retained portion 13 of a starting block and / or a veneer block. Alternatively, the cavity can be delimited on its lower side by the oven floor 90.

[0061] To form the inner side of the mold, an inner portion of the mold is placed only on an upper portion 54 of the outer face of the glass. The mold is thus delimited by an inner portion of the mold and by a lower portion 55 of the exposed face 53 of the cooled glass. The inner portion of the mold is separate and distinct from the outer portion 30 of the mold. Figures 7A to 7F illustrate several embodiments of an inner portion of the mold.

[0062] In a preferred embodiment, with reference to [Fig. 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 that will be in contact with the wall after the repair; that is, it considerably limits the creation of defects, contamination of the glass, and the formation of bubbles that could hinder the glass placement. By way of illustration and without limitation, such an inserted block 40 may be made of chromium oxide, electrofused or agglomerated alumina-zirconia-silica (AZS), electrofused or agglomerated alumina, or mullite-zirconia.

[0063] The inserted block 40 is retained in this position after the tank repair. The inserted block 40 thus forms, together with the material used to fill the cavity, the new wall of the tank.

[0064] During impression filling, 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 comprising a bar 80 fixed to a top and / or outer face of the inserted block 40. Such a bar 80 is typically removable and can be taken out at the end of the repair process. For example, each bar can be inserted into a hole arranged on a top or outer face of the inserted block 40.

[0065] In one variant, with reference to [Fig. 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.

[0066] The external part 30 of the formwork is fixed to the furnace rim 95 and to one or more fixing sub-layers 92, 93 below the furnace floor 90. Other sub-layers 91 can be arranged between the floor 90, the rim 95 and the fixing sub-layers 92, 93.

[0067] The presence of a portion of the wall blocks 13 and the fixing of the external part 30 of the formwork are independent of the type of internal formwork. Thus, fixing 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.

[0068] Alternatively, with reference to [Fig.7C], the inserted block can be held by a push bar 82 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.

[0069] In some cases, as illustrated in [Fig. 7C], the thrust bar 82 extends through the outer part 30 of the formwork. In this case, the outer part 30 of the formwork is provided with an opening 85 forming a passage for the thrust bar 82. In other cases (not illustrated), the thrust bar extends outwards above the upper edge of the outer part of the formwork. In some embodiments, a primary or supplementary support system may be arranged on the underside of the block.

[0070] 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 cavity. In other embodiments, with reference to [Fig. 7D], the thickness D of the inserted block 40 corresponds to the thickness of the wall to be formed.

[0071] With reference to [Fig. 7E], the inserted block 40 typically has a trapezoidal cross-section. The upper face 40S of the inserted block is intended to form, partially or entirely, the upper face of the replacement wall of the tank. Typically, the aforementioned top face 40S of the inserted block is aligned with the initial height of the tank.

[0072] The inner face 401 of the inserted block 40 extends along the upper part 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 401 typically extends to a height Hs of at least 75 to 100 mm below the free face 58 of the glass. The face internal 401 of the inserted block is typically smooth and adapted to establish good mechanical contact with the exposed face 53 of the cooled glass.

[0073] The outer face 40E of the inserted block may extend parallel to the inner face 401 or obliquely. When the outer face 40E is intended to be covered during the filling of the cavity, it may have a texture that facilitates the adhesion of the filling material, for example, perforations or grooves. When the width D of the inserted block corresponds to the width of the cavity, the outer face 40E of the inserted block is intended to form part of the outer wall of the tank. In this case, the outer face 40E is typically smooth.

[0074] The lower face 40B of the inserted block 40 is preferably oblique, so that the height H! of the inner face of the inserted block 40 is greater than the height HE of the outer face of the inserted block 40.

[0075] The oblique orientation of the lower face 40B of the inserted block 40 allows air to escape during the filling of the cavity, both from the air contained within the cavity and from any air bubbles present in the filling material. This prevents the creation of porous areas in the replacement cavity wall.

[0076] 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 cavity-filling material for wall wear measurements at a later stage. For example, this interface can be detected by radar-type measurements. From information on the geometry and position of the inserted block, the corrosion of the inserted block and the interface can be determined, and thus the time required for further wall repair can be anticipated.

[0077] Preferably, the underside of the lower face 40B of the inserted block has a roughness that promotes adhesion of the material used to fill the cavity. For example, the underside of the inserted block may have a texture such as grooves or perforations for gripping.

[0078] In another embodiment, with reference to [Fig. 7F], the inner part 40 of the casing 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 retaining 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.

[0079] As with the inserted block described above, the plate is retained in the replacement wall after the repair. Thus, the plate 41, together with the material used to fill the cavity, forms a new wall of the tank.

[0080] The upper edge of the inserted plate 41 is intended to form part 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 a height Hs of at least 75 to 100 mm below the free face 58 of the glass.

[0081] In a third embodiment, with reference to [Fig. 7G], the internal part of the formwork 42 is removable, allowing for its removal after the cavity has been filled. A removable internal part of the formwork 42 is typically made of metal. Such an internal part of the formwork 42 can be cooled entirely or partially, for example by one or more streams of cold water circulating inside the internal part of the formwork 42.

[0082] Typically, the internal part of the removable casing 42 comprises a predominantly vertical plate 44 extending parallel to the exposed face 53 of the cooled glass, and a predominantly horizontal plate 43 integral with the predominantly vertical plate 44. The predominantly 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. By way of illustration and without limitation, the vertical plate 44 extends to a height of between 5 and 25 cm above the free face of the cooled glass. The predominantly horizontal plate 43 covers the footprint above the portion of the tank to be replaced. The internal part of the casing is typically held in place at the horizontal plate 43.

[0083] For the various embodiments described above, the internal casing 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 used directly to delimit the impression and does not have any internal casing.

[0084] After the installation of the external and internal parts of the formwork, with reference to [Fig.8], the cavity 20 is filled with an unshaped material 21. By an unshaped material, we mean a mixture of particles and liquid capable of flowing so as to fill the cavity.

[0085] Said unshaped material is suitable for forming a refractory material after hardening. Preferably, the unshaped material is a hot-setting material and can withstand rapid evaporation of the liquid contained in the mixture, for example a material comprising a mixture of sintered or electrofused AZS grains, sintered or electrofused mullite-zirconia grains, tabular alumina grains or electrofused alpha-beta alumina grains, zirconia, silica and / or chromium oxide grains, or mixtures thereof.

[0086] Advantageously, the unshaped material is a colloidal or phosphatic setting material or a sodium silicate type setting material. Such materials allow to obtain very good mechanical resistance when casting and solidification are carried out at high temperatures, for example above 300°C.

[0087] Colloidal setting products are prepared with a liquid binder of the colloidal silica type. Evaporation of the water contained in the binder causes a silicic-type freeze-thaw setting. Such a material is, for example, sold by Magneco Metrel under the name "Metpump AZS". Phosphatic setting products contain phosphatic acid and, during the solidification reaction, form aluminum phosphate, which exhibits high corrosion resistance, very good mechanical strength above 350°C, and very good thermal shock resistance. Such materials are, for example, marketed by DSF under the name Duropave 95 Mortar, and by RHI under the name RESISTIT "ZM 260".

[0088] Alternatively, the unshaped material may be a hydraulically setting material such as a cement, for example an aluminous refractory cement.

[0089] In the case of an internal formwork component in the form of an inserted block, the choice of the unshaped material is adapted to the material of the inserted block. This optimizes the bond between the unshaped material and the block, and minimizes corrosion during furnace operation.

[0090] A combination of said materials can also be chosen to optimize corrosion resistance and, in some cases, the detection of the interface between the inserted block and the refractory material derived from the unshaped material. This is particularly useful for performing wear analysis via radar detection of said interface.

[0091] Table 1 illustrates several preferred combinations of bases for refractory materials.

[0092] [Tables 1] Inserted block Unshaped material Chromium oxide AZS AZS AZS Electrofused alumina Tabular alumina High Electrofused zirconia AZS Chromium oxide Chromium oxide

[0093] The cavity is filled with the unshaped material up to a height HP of the replacement wall. Typically, the unshaped material is poured into the cavity using a pump. When the thickness D of the inserted block 40 corresponds to the width of the cavity, as illustrated in [Fig. 7E], the filling is typically achieved by a chute 48 passing through the external part 30 of the formwork. In other cases, the filling can be carried out through the opening at the top of the cavity.

[0094] Before casting, the unshaped material is at a temperature close to ambient temperature, typically between 15°C and 30°C. When the unshaped material comes into contact with the wall of the cooled glass, its temperature rises rapidly to the glass's repair temperature (TR), 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 temperature increase causes the free water in the mixture to evaporate, increasing its viscosity until the material solidifies according to the colloidal setting phenomenon. Setting can also be achieved at a higher temperature by phosphate setting before the actual ceramicization of the material.

[0095] After a solidification time which is typically between 5 and 180 minutes, the setting of the unshaped material is complete throughout the entire volume.

[0096] After the unshaped product has set, the retaining system for the inner part of the mold is removed, or, in the case of a removable inner part of the mold, the inner part of the mold itself is removed. In this embodiment, removing the inner part of the mold 42 in contact with the glass prevents any contamination and / or formation of bubbles in the glass.

[0097] The 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, leading to the melting of the glass 50. The unshaped material solidified in the mold cavity is heated by the glass 50 to a temperature close to that of the molten glass. This heating causes the unshaped material to sinter, increasing its mechanical strength and corrosion resistance.

[0098] In the case of a non-removable internal formwork part, 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 part.

[0099] In the case of an internal part of removable formwork, with reference to [Fig.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.

[0100] The use of an unshaped material allows the replacement wall to be adapted to the geometry of the impression, which allows the repair to be adjusted to the conditions on site during the repair with great flexibility.

[0101] The shape of the replacement wall, adjusted to the geometry of the cooled glass, also makes it possible to obtain homogeneous heating of the unshaped material in contact with glass. In addition, the use of an unshaped material facilitates the delivery of the replacement wall because this method requires no transport and installation of pre-formed blocks which are typically heavy and fragile.

[0102] After solidification and / or sintering of the unshaped 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 outer face of the replacement wall during furnace operation.

[0103] In certain 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 a power source outside the tank. Alternatively, the sensor may be a system comprising one or more thermocouples.

[0104] Typically, the sensors are installed at different heights and / or distances from the outer wall of the cavity before the unshaped 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 unshaped material. In this step, the sensors are embedded in the wall.

[0105] During the operation of the repaired furnace, the replacement wall is subjected to corrosion, and the outer surface of the molten glass approaches the sensor locations. The sensors thus successively reach a maximum operating temperature and subsequently 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 temperature increase and eventually by the corrosive nature of the glass. When a wire is destroyed, the electrical current flowing through that wire is interrupted. In this way, it is possible to determine the corrosion progression at each sensor location and, by extrapolation, to determine the overall corrosion progression of the entire wall.Depending on the positioning of the sensors, information can be obtained on the wear profile across the width and height of the wall. This information makes it possible to anticipate future wall repairs and prevent the risk of molten glass leakage.

[0106] Such wear detection systems can be used as soon as the repair process is complete.

Claims

Demands

1. A method for repairing a wall of a furnace (10) containing molten glass, comprising: • solidifying at least a portion of the glass (50) contained in the furnace in contact with a damaged portion (11, 12) of the furnace wall, • removing the damaged portion (11, 12) of the furnace wall down to the solidified glass (51), • installing a formwork (30, 40, 41, 42) defining, with the solidified glass (51), an imprint (20) of the portion of the wall to be replaced, said formwork (30, 40, 41, 42) comprising an external portion (30) and an internal portion (40, 41, 42), the internal portion (40, 41, 42) extending into a region of the free surface (58) of the glass (51) such that the imprint (20) is delimited internally, in an upper portion (54), by the internal part of the formwork (40, 41, 42) and, in a lower portion (55), by an exposed face (53) of the solidified glass (51),• the pouring of an unshaped material (21) into the mold (20), • the solidification of the unshaped material, • the return of the solidified glass (51) to its molten state.

2. A method according to claim 1, wherein 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.

3. Method according to claim 2 wherein the internal part of the formwork comprises chromium oxide, alumina-zirconia-silica, alumina or zirconia.

4. A method according to claim 2 or claim 3, wherein the internal part (40) of the formwork comprises an inserted block (40) of refractory material held by a retaining system (80, 82), the method further comprising the removal of the retaining system (80, 82) after the pouring of the unshaped material.

5. Method according to claim 1, wherein the internal part (41) of the formwork comprises a vitreous silica plate or a glass plate or a glass fiber plate.

6. Method according to claim 1, wherein the internal part (42) of the formwork is removable, the method further comprising a removal of the internal part of the formwork after the pouring of the unshaped material (21) into the cavity (20).

7. Method according to claim 6, wherein the internal part (42) of the formwork comprises a metal reinforcement.

8. Method according to claim 6 or claim 7, further comprising cooling of the internal part (42) of the formwork.

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

10. A method according to any one of the preceding claims, wherein the unshaped material (21) is a phosphate-set material, a colloidal-set material, or a sodium silicate-type set material.

11. A method according to any one of the preceding claims, wherein a lower part of the indentation (20) is delimited by a residue (13) of the tank wall to be repaired.

12. A method according to any one of the preceding claims, wherein the removal of the damaged part (10, 11) of the tank includes the removal of a portion (52) of the solidified glass.

13. A method according to any one of the preceding claims, further comprising embedding at least one wear sensor (70) in the unshaped material (21).

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