Glass manufacturing process and improved hybrid furnace capable of manufacturing glass according to such a process

Abstract

Glass manufacturing process and improved hybrid furnace suitable for manufacturing glass according to such a process The invention relates to a glass manufacturing process in a hybrid furnace, in particular intended to supply at least one fiber-making unit, comprising means for melting vitrifiable materials formed by burners and electrodes immersed in the glass bath, and comprising at least bubbling elements and preferably an immersed wall, characterized in that at least a part of said bubbling elements is selectively controlled, according to a determined threshold value corresponding to the share of electrical energy in the total energy used by said melting means, respectively according to at least: - a first mode (called active) of operation when the share of electrical energy is less than said threshold; - a second mode (called passive) of operation when the share of electrical energy is greater than said threshold.The invention also relates to a process for preparing glass fibers and an improved hybrid furnace capable of manufacturing glass according to such a glass manufacturing process. Figure for the abstract: Figure 1.

Description

Title of the invention: Glass manufacturing process and improved hybrid furnace suitable for manufacturing glass according to such a process. Technical field of the invention

[0001] The invention relates to a method for manufacturing glass and an improved hybrid furnace for manufacturing glass according to such a method.

[0002] The invention relates more particularly to a method for manufacturing glass in a hybrid furnace comprising means for melting vitrifiable materials formed by burners and electrodes immersed in the glass bath, and comprising at least bubbling elements, or preferably an immersed wall. The invention also relates to the use of such a hybrid furnace for the manufacture of glass with a high degree of hybridization, that is to say a substantial part of electrical energy in the total energy used by said melting means.

[0003] The invention further relates to an improvement of such a hybrid furnace for the manufacture of glass according to said manufacturing process.

[0004] The glass manufacturing process and the hybrid furnace according to the present invention are in particular, but not exclusively, intended to supply one or more fiber-making unit(s) for the transformation of said manufactured glass into fibers. Technical background

[0005] Various examples of glass manufacturing furnaces are known from the prior art, the design of which depends in particular on the product to be manufactured, that is to say, the final shaping of the glass. Thus, different designs of furnaces intended to supply glass manufacturing installations can be distinguished, in particular depending on whether the manufacturing process ultimately involves the industrial forming of hollow glass, flat glass, or glass fibers such as glass wool, rock wool, or textile glass yarns.

[0006] One of the industrial challenges in the design of glass furnaces is to be able to obtain glass whose quality and quantity requirements depend on the product to be manufactured, which also determines the mixture of vitrifiable materials, also called the "composition" (or "batch"), which is melted in the glass furnace. The mixture of vitrifiable materials is, for example, made up of conventional raw materials to which cullet, consisting of glass fragments, is advantageously added—in an ever-increasing proportion—in order to promote melting and reduce the carbon footprint (CO2 footprint) associated with the glassmaking process.

[0007] In this description, "vitrifiable materials," or sometimes "raw materials," means all materials, natural ores or synthesized products, recycled materials such as cullet, etc., that can be used in the composition used to feed a glass furnace. This includes sand, but also all additives (sodium carbonate, limestone, dolomite, alumina, etc.), waste (including mineral fibers) that may come from the production of said fibers or from construction or deconstruction sites, all possible liquid or solid fuels (plastic, composite or non-composite materials, organic matter, coal), and all types of cullet.Also included are recyclable materials containing combustible (organic) elements, such as, for example, coated mineral fibers with a binder (of the type used in thermal or acoustic insulation or in reinforcing plastics), laminated glass with polyvinyl butyral polymer sheets such as windshields, glass bottles (household cullet), or any type of "composite" material combining glass and plastics such as certain bottles. Also recyclable, under certain conditions and depending on the application, are "glass-metal composites or metallic compounds" such as functionalized glass with coatings containing metals. In the description, "glass bath" or "glass bath" refers to the product of melting these raw materials.

[0008] Similarly, "glass" is understood to mean glass in the broad sense, that is to say, encompassing any material with a vitreous matrix.

[0009] In addition, the term "manufacturing" includes the indispensable melting stage of the vitrifiable materials and, where applicable, all subsequent / complementary stages aimed at refining / conditioning the molten glass for its final shaping, in particular in the form of flat glass (windows), hollow glass (flaps, bottles), glass in the form of mineral wool (in particular rock wool or glass wool) used for its thermal or acoustic insulation properties, or even possibly glass in the form of continuous so-called textile yarns used further in reinforcement.

[0010] The choice of energy used for melting vitrifiable materials thus leads to distinguishing mainly two major designs of furnace for glassmaking, respectively flame furnaces and electric furnaces.

[0011] According to the first design, flame furnaces generally use fossil fuels, in particular natural gas for the burners, the thermal energy is thus transmitted to the glass by heat exchange between the flames and the surface of the glass bath.

[0012] According to the second design, electric furnaces are furnaces in which thermal energy is produced by the Joule effect within the mass of molten glass. Indeed, glass, an insulating substance at room temperature, becomes electrically conductive at high temperatures, so it is possible to use the Joule effect within the glass molten glass itself to heat it.

[0013] Besides these two designs, there is also a third design of ovens, called “hybrid” ovens.

[0014] The present invention relates to such a hybrid furnace for the manufacture of glass in which several energy sources are combined, respectively by combustion and electrical, the melting being based on a flame furnace but also using an auxiliary electric heating, also referred to by the English term "boosting".

[0015] The addition of supplementary electric heating (or "boosting") by means of electrodes further improves the melting capacity of flame furnaces, which is limited by the heat transfer occurring between the flame and the surface of the glass bath, as well as the quality of the glass. Advantageously, the addition of electrodes makes it possible, where necessary, to increase the temperature of the glass bath without compromising the furnace superstructure, particularly when the maximum dome temperature has been reached and it is not possible to increase the temperature using the flame burners.

[0016] Nevertheless, the operation of such a hybrid furnace still relies mainly on the use of a combustible energy, generally a fossil energy such as gas, so that the impact ultimately obtained on improving the carbon footprint of the glassmaking process remains limited.

[0017] Indeed, the electricity powering the electrodes is only used as a supplement, generally representing 10 to 15% of the total energy used to carry out the melting stage, so its impact on the manufacturing carbon footprint is proportional. Moreover, to effectively improve the carbon footprint, the electricity used must be so-called "green" electricity, that is, electricity produced from renewable and decarbonized energy sources.

[0018] In this description, the term "hybridization rate" refers to the proportion of electrical energy relative to fuel energy in the total energy used by the melting means during the melting of vitrifiable materials. Thus, the greater the proportion of electrical energy relative to the total energy, the higher the hybridization rate of the furnace.

[0019] In such a hybrid furnace, the electrodes also participate, according to their arrangement, in modulating the movements in the glass bath, typically according to a convection belt, thus facilitating the conduction of the melt in the manufacturing process of the glass.

[0020] Furthermore, it is also known to use in a glass furnace, for example for the production of glass wool, one or more "bubblers", that is to say a system for injecting at least one gas, such as air or nitrogen, at the level of the hearth, the bubbles of which then create an upward movement of the glass.

[0021] Thus, it is known for example to install transversely (i.e. perpendicular to a longitudinal direction of glass flow), over the entire width or almost, a row of bubblers at the level of the furnace floor.

[0022] Advantageously, the bubbling elements promote glass convection and improve the thermal homogeneity of the glass bath. Thanks to this improved homogeneity, the glassable materials are more effectively melted and transformed into glass. Indeed, the bubbling elements, through gas injection, promote the upward movement of the glass, which, located at the hearth level, has a lower temperature than at the surface. At the surface of the glass bath, the glass temperature is comparatively higher due to heat transfer occurring with the flames from the burners in the furnace.

[0023] For various reasons, including research conducted to improve the carbon footprint of the glass manufacturing process and notwithstanding existing prejudices about the limits in the share of electrical energy that can be used during melting, the Applicant has carried out studies (tests and / or simulations) with the aim of designing a hybrid furnace capable of increasing the hybridization rate, that is to say, the share of electrical energy in the total energy used by the melting means during the melting of vitrifiable materials, in other words, the share of electrical energy relative to that of fossil energy (such as natural gas) used as fuel, generally with oxygen as an oxidant, to power the burners.

[0024] However, by reducing the combustion carried out with the burners to decrease the share of fossil energy in the total energy, there follows a reduction in the heat exchange between the flames and the surface of the glass bath so that the temperatures at the surface of the glass bath heated by the flames are lower.

[0025] Concurrently, by increasing the proportion of electrical energy, the glass temperatures are higher at the base, where the electrodes are generally mounted (alternatively, all or part of the electrodes are arranged in the side walls, for example in the form of protruding bars embedded below the surface of the glass bath). Thus, it is generally accepted that any increase in the proportion of electrical energy (i.e., electricity) is accompanied by a change in the glass temperatures throughout the depth of the bath and, consequently, in the convection of the glass, which has consequences for the quality of the glass. In particular, increasing the proportion of electrical energy beyond 15% of the total energy used by the hybrid furnace's melting mechanisms during the melting of glassable materials is considered a technical limit. This is because it is also necessary to maintain a hot spot (i.e., a sufficient temperature) on the surface of the glass bath. For this reason, electrical energy generally represents less than 15% of the total energy in a hybrid furnace and, as explained previously, only serves as a supplement (known as "boosting"). Typically, in a hybrid furnace, electrical energy represents 5 to 10% of the total energy.

[0026] However, contrary to the prejudices of the person in the trade regarding such a threshold of electrical energy, the studies carried out by the Applicant have established that the share of electrical energy in the total fusion energy is not the only cause impacting the quality of the glass due to changes in the temperatures of the glass.

[0027] Indeed, studies have shown that the simultaneous use of electrodes and bubblers in a conventional hybrid furnace modifies the short-term residence time of the glass because the bubblers agitate the glass in conjunction with the electrodes, which further accelerates the removal of the glass present at the surface of the glass bath. However, when the proportion of electrical energy is increased beyond 15 to 20%, the glass present at the surface is of lower quality due to the lower temperatures resulting from the reduced combustion with the burners, and moreover, the glass is not thermally homogeneous. Consequently, the bubblers then accelerate the removal of glass that does not meet the required quality standards, for example, glass containing unmelted material, for the reasons detailed below.

[0028] Indeed, the vitrifiable materials introduced into the furnace initially float on the glass bath and are generally melted in the first half of the hybrid furnace, in the zone where the fossil fuel contribution represents 90 to 95% of the total melting energy. However, with a lower proportion of fossil fuel contribution in favor of an electrical contribution exceeding the aforementioned threshold, the vitrifiable materials will then move further downstream in the furnace and, in so doing, approach the furnace outlet, or may even reach it.

[0029] Thus, if "contamination" is present in the glass (particularly from cullet), for example from ceramics, heat-resistant glass, glass-ceramics, or refractories, these pollutants have less time to melt in the furnace, that is, to be "digested," which is why they are generally referred to as unmelted material. Moreover, as the proportion of cullet continues to increase, reaching, for example, 50%, sometimes 70% or even more, the presence of such pollutants, and therefore unmelted material, in the glass also tends to increase. Now, the presence of unmelted material in the glass produced in the furnace hybrid directly impacts quality, and may even pose specific problems depending on the application.

[0030] For example, in the case of using this glass for the manufacture of glass fibers, such as glass wool, textile glass yarns, these unmelted elements present in the glass are likely to affect the fiber-making process, in particular to interrupt it in the event of clogging of holes in a plate that includes a fiber-making unit.

[0031] During the said studies, with a share of electrical energy exceeding the threshold of 15% to 20% of the total energy used during the melting of the vitrifiable materials in the hybrid furnace, for example a share between 25% and 55%, it was established that the conventional use of the boilers contributed to a significant degradation of the quality of the glass produced, in particular an increase in the presence in the glass of unmelted materials such as ceramics.

[0032] The object of the invention is to propose a new glass manufacturing process in a hybrid furnace comprising bubbling elements, or even a new design of such a hybrid furnace, to increase the share of electrical energy used beyond 15% of the total energy (in other words, to reduce the share of fuel energy), in particular in order to reduce the carbon footprint of the glass manufacturing process through the use of electricity obtained from so-called "green" electricity, that is to say, electricity which is produced from renewable and decarbonized energy sources, and this while maintaining the quality of the glass manufactured.

[0033] According to an important feature, the Applicant's demonstration of the impact on the quality of the glass of the simultaneous use of the bubblers and the electrodes in a hybrid furnace operating with a high degree of hybridization, i.e. advantageously a share of electrical energy beyond the threshold of 15% of the total energy used by the melting means during the melting of the vitrifiable materials, constitutes a further step in its own right of the present invention. Summary of the invention

[0034] To this end, the invention proposes a method for manufacturing glass in a hybrid furnace comprising at least bubblers and an improved hybrid furnace of this type for manufacturing quality glass with a high hybridization rate, in particular above the threshold of 15% of the total energy.

[0035] According to a first aspect, the invention relates to a method for manufacturing glass in a hybrid furnace, in particular intended to supply at least one fiber-making unit, comprising means for melting vitrifiable materials formed by burners and electrodes immersed in the glass bath, and comprising at least bubbling elements, characterized in that at least a part of said bubbling units is selectively controlled, according to a determined threshold value corresponding to the share of electrical energy in the total energy used by said melting means, respectively according to at least: - a first mode (called active) of operation when the share of electrical energy is below said threshold; - a second (so-called passive) mode of operation when the share of electrical energy is greater than said threshold.

[0036] Advantageously, the glass manufacturing process according to the invention is implemented in a hybrid furnace preferably comprising a submerged wall.

[0037] Advantageously, said submerged wall is located downstream of the bubblings.

[0038] Said means for melting vitrifiable materials are formed by the totality of the burners and electrodes immersed in the glass bath used selectively for melting the vitrifiable material.

[0039] The principle of the invention is based on a selective use of the bubblers according to the rate of hybridization and results in a low use or even the stopping of bubblers with a high rate of hybridization.

[0040] Advantageously, such selective use of the bubblers by no longer keeping them active at high hybridization rates, as is otherwise the case with these bubblers at low hybridization rates, makes it possible to reduce the temperature at the level of the hearth which makes it possible to reduce the corrosion of the blocks made of refractory material.

[0041] Advantageously, reducing or even stopping the bubbling in the second passive mode of operation, when the hybridization rate is high, i.e. a share of electrical energy beyond said threshold value, makes it possible to increase the roof temperature (which tends to decrease due to the less use of the burners in favor of the electrodes).

[0042] At a high hybridization rate, the layer (or crust) of vitrifiable material tends to lengthen and extend further downstream due to the lowering of the hot spot temperature. Notwithstanding this downstream movement of the demarcation line, stopping the bubbling chambers advantageously maintains the quality of the glass produced.

[0043] Advantageously, the second passive operating mode of the bubblers makes it possible to increase the surface temperature of the glass bath.

[0044] Advantageously, the second passive operating mode of the bubblers makes it possible to increase the residence time of the glass and thereby promotes obtaining a quality glass.

[0045] According to other features of the manufacturing process according to the invention: - the threshold value determining the selection of the operating mode of the bubblers corresponds to a share of electrical energy of at least 15% of said total energy, that is to say greater than or equal to 15% of the total energy implemented by said melting means, preferably said threshold value is between 15% and 25% of said total energy, more preferably between 15% and 20% of said total energy; - at least part of said bubbling units is controlled in the first mode (called active) so as to operate between 80% and 100% of their nominal capacity, for example with a flow rate between 5 and 20 liters per minute, preferably with a flow rate between 8 and 10 liters per minute; - at least part of said bubbling units is controlled in the second mode (called passive) so as to operate between 0% (i.e. switched off) and 20% of their nominal capacity, preferably with a flow rate less than or equal to 2 liters per minute; - the share of electrical energy in the total energy used by said melting means for the melting of vitrifiable materials is less than or equal to 50%, or even 60%; - the burners are controlled, advantageously by a furnace control unit, to maintain a roof temperature which is greater than 1100°C, preferably greater than 1150°C; - the oven is of the type in which said hybrid oven bubbling units are positioned so as to form at least one transverse row, said bubbling units comprising at least two rows which are capable of being controlled independently of each other, that is to say, controlled selectively at least by row, in particular capable of being controlled differently from each other; - the hybrid furnace is of the type comprising a submerged wall upstream of which at least the said bubbling elements are arranged and in which the said electrodes comprise at least one group of electrodes - also called the first group of electrodes when the furnace comprises more than one group of electrodes - electrodes which are arranged upstream of the said bubbling elements, the said bubbling elements being selectively controlled according to the invention; - the hybrid oven is of the type comprising a submerged wall upstream of which at least said bubbling elements are arranged and in which said electrodes comprise at least a first group of electrodes arranged upstream of said bubbling elements and at least a second group of electrodes arranged between said bubbling elements and the submerged wall, said bubbling elements being selectively controlled according to the invention; - the second group of electrodes is selectively powered according to the aforementioned determined threshold value, the second group of electrodes being powered only when the bubblers operate according to a second (so-called passive) mode of operation.

[0046] According to another aspect, the invention relates to a process for preparing glass fibers such as glass wool, rock wool or textile glass yarns, comprising the process of manufacturing glass according to any one of the preceding features of the invention, followed by the transformation into fiber by at least one fiber-making unit of said manufactured glass.

[0047] According to a second aspect, the invention relates to a hybrid furnace for glassmaking, particularly intended for implementing the glassmaking process according to the invention, said hybrid furnace comprising means for melting vitrifiable materials formed by burners and electrodes immersed in the glass bath, said electrodes forming at least one group of electrodes arranged upstream of bubbling elements and preferably of a submerged wall, characterized in that the furnace comprises at least one control unit capable of selectively controlling at least a portion of said bubbling elements according to a determined threshold value corresponding to the proportion of electrical energy in the total energy used by said melting means for melting vitrifiable materials, respectively according to at least: - a first mode (called active) of operation when the share of electrical energy is below said threshold; - a second (so-called passive) mode of operation when the share of electrical energy is greater than said threshold.

[0048] Advantageously, the hybrid furnace for glass manufacturing according to the invention is in particular intended to supply at least one fiber-making unit.

[0049] According to other features of the hybrid oven according to the invention: - the hybrid furnace is of the type in which said at least one group of electrodes comprises a first group of electrodes arranged upstream of bubblers and a submerged wall (located downstream of the bubblers), said furnace being characterized by the fact that at least a second group of electrodes is arranged between the bubblers and said submerged wall; - the electrodes of the second group are arranged along at least one transverse row of electrodes, preferably a single transverse row, to form a barrier, called the second barrier; - the electrodes of the second group are arranged in the downstream half of the furnace having a length L, i.e. at more than 50% of the length L, preferably in the last downstream third of the furnace having a length L, more preferably in an area between 80% and 90% of said length L; - the bubblers are arranged so as to form at least one transverse row, preferably a transverse row, said at least one row of bubblers being arranged in the downstream half of the furnace having a length L, that is to say at more than 50% of the length L, preferably in the last downstream third of the furnace, more preferably in an area between 70% and 80% of said length L; - the electrode group, referred to as the first group, comprises a first set of electrodes for heating the glass homogeneously which is arranged upstream of a second set of electrodes, said second set of electrodes comprising at least one transverse row to form a barrier, referred to as the first barrier; - the first set of electrodes has a number NI of electrodes between 8 and 14, for example 12 electrodes forming a pad, and the second set of electrodes has a number N2 of electrodes between 4 and 9 per row, for example 6 electrodes forming a transverse row; - the electrodes are arranged at the level of a furnace floor so that said electrodes extend vertically from the floor, said electrodes being totally immersed in the glass bath.

[0050] Advantageously, said electrodes of the second group are particularly suitable for acting on the convection loop, in particular to oppose the downstream progression of vitrifiable materials present on the surface of the glass bath.

[0051] Advantageously, said electrodes of the second set of electrodes of the first group comprise at least one transverse row to form a barrier, called the first barrier, capable of acting on the convection loop in particular to oppose the downstream progression of the vitrifiable materials present on the surface of the glass bath.

[0052] Advantageously, the hybrid furnace includes means for measuring the temperature of the roof, for example at least one thermocouple or any other suitable means, said measuring means being connected to the control unit (CU), in particular to selectively control the burners according to a roof temperature setpoint such as a temperature of 1100°C, preferably 1150°C.

[0053] Advantageously, the hybrid furnace includes a submerged throat through which the glass flows out of the furnace, said throat opening into a wall delimiting the furnace downstream.

[0054] Advantageously, the hybrid furnace includes at least one niche for loading vitrifiable materials via at least one loading device, preferably two niches arranged transversely opposite each other in the first upstream third of the furnace.

[0055] Advantageously, the hybrid furnace includes means for evacuating fumes, such as at least one chimney, arranged in the first upstream third of the furnace of length L, preferably said evacuation means open into a wall delimiting the furnace upstream.

[0056] Advantageously, the hybrid furnace includes means for cooling the bubbling elements, said cooling means using a heat transfer fluid for cooling, which is, for example, water or air. Alternatively, the bubbling elements are not cooled.

[0057] In a hybrid furnace according to the invention, the bubblers are selectively controlled, thereby increasing the residence time of the glass when melting is carried out with a high degree of hybridization, the glass advantageously exhibiting the desired quality, in particular determined in relation to the number of unmelted pieces, and this despite the fact that the surface temperature of the glass bath is lower due to the reduction of the share of combustible energy in favor of the share of electrical energy in the total energy. Brief description of the figures

[0058] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which: - [Fig.l] is a side view which schematically represents a hybrid furnace for the manufacture of glass according to a first embodiment, said furnace further comprising successively from upstream to downstream electrodes, a row of bubblers and a submerged wall; - [Fig.2] is a top view of the hybrid furnace according to [Fig.1]; - [Fig.3] is a side view which schematically represents a hybrid furnace, called improved, for the manufacture of glass according to a second embodiment, said furnace further comprising successively from upstream to downstream of electrodes, a row of bubblers, a row of electrodes and a submerged wall; - [Fig.4] is a top view of the hybrid furnace according to [Fig.3]. Detailed description of the invention

[0059] In the rest of the description, the longitudinal, vertical and transverse directions will be adopted without limitation with reference to the trihedron (L, V, T) shown in the figures.

[0060] The terms "upstream" and "downstream" shall also be used, without limitation, to refer to the path of the glass in the furnace along the longitudinal direction, from the introduction of vitrifiable materials upstream to the exit of the glass downstream. The terms "upper" and "lower" or "top" and "bottom" shall also be used in reference to the vertical direction and finally "left" and "right" in reference to the transverse direction.

[0061] Figure [1] shows a first embodiment of a hybrid furnace 10 for the manufacture of glass, in particular intended to supply a fiber-making unit (not shown) for the transformation of said glass into fibers.

[0062] The hybrid furnace 10 mainly comprises a structure made up of blocks of suitable refractory material which are conventionally distinguished according to whether said blocks are in contact with the glass or not.

[0063] Indeed, the set of blocks in contact with the glass is conventionally called the "infrastructure," and the set of materials arranged above the infrastructure is called the "superstructure." The superstructure material, which lies above the tank blocks of the infrastructure and is not in contact with the glass but with the atmosphere inside the furnace, is generally of a different nature than that of the infrastructure blocks.

[0064] Preferably, the hybrid furnace 10 is parallelepiped in shape, generally rectangular. The hybrid furnace 10 comprises, on the one hand, a wall 12 and a wall 14 which, extending transversely, respectively delimit the upstream and downstream ends of the furnace along the longitudinal direction of the trihedron (L, V, T) and, on the other hand, a wall 16 and a wall 18 which, extending longitudinally, respectively delimit the furnace along the transverse direction.

[0065] The hybrid furnace 10 extends longitudinally over a length "L", corresponding respectively by convention to the distance between the upstream wall 12 and the downstream wall 14 located on the opposite side.

[0066] As defined above, the terms "upstream" and "downstream" correspond in the present description to the direction of flow of the glass in the hybrid furnace 10, the glass flowing from upstream to downstream along a median longitudinal axis A-A' of the furnace (upstream at A, downstream at A') shown in [Fig.2].

[0067] The superstructure of the hybrid furnace 10 includes a vault 20, referred to as the "hot vault". Advantageously, at least part or preferably all of the vault 20 is of the low-profile type, i.e. having a reduced height, in particular determined in relation to a surface S of the glass bath 15.

[0068] Preferably, the low-profile vault has a height at the apex (highest point) relative to the surface S of the glass bath 15 which is for example between 900 mm and 1400 mm.

[0069] Advantageously, the hybrid furnace 10 includes means 120 for measuring the internal temperature above the glass bath 15. The measuring means 120 are, for example, comprised of at least one thermocouple or any other equivalent means.

[0070] Preferably, the temperature is measured at the level of vault 20 and is therefore designated as "vault temperature" in the rest of the description.

[0071] The infrastructure of the hybrid furnace 10 forms a tank which, intended to contain the molten glass bath 15, includes a base 22. Preferably, the base 22 is flat so that the depth of the glass bath 15, between the surface S of the glass bath 15 and the base 22, is substantially constant.

[0072] The hybrid furnace 10 includes at least one niche 24, provided in the superstructure, so as to load a mixture of vitrifiable materials 25 or composition (“batch” in English) inside the furnace, said vitrifiable materials being intended to be transformed into glass during the melting stage of the manufacturing process.

[0073] Advantageously, the mixture of vitrifiable materials 25 includes cullet consisting of glass debris which, obtained by recycling glass, is crushed and cleaned before being added to the mixture to manufacture glass again.

[0074] Cullet promotes melting, that is, the transformation of the mixture of vitrifiable materials 25 into glass by melting. Furthermore, cullet allows for the recovery of used glass through recycling (glass being infinitely recyclable), thereby reducing the quantities of raw materials needed to manufacture glass proportionally, which contributes to reducing the carbon footprint. Preferably, cullet represents more than 50% of the mixture of vitrifiable materials 25 and up to 70% or even 80%, which generally contributes directly to the presence of pollutants and therefore to the risk of the glass containing unmelted material.

[0075] Preferably, the hybrid oven 10 comprises two niches 24 arranged transversely opposite each other and opening into the oven through an opening 26, advantageously in the first upstream third of the oven of length L. In an alternative not shown, the hybrid oven 10 comprises a niche 24 provided in the upstream wall 12.

[0076] In a known manner, the vitrifiable materials 25 are introduced into the hybrid furnace 10 by means of at least one loading device 28, also called a "loader", schematically represented by an arrow on the [Fig.2].

[0077] As illustrated in [Fig.1], the surface S of the glass bath 15 is partially covered, at least upstream, by a mat of vitrifiable materials 25 materialized in [Fig.1].

[0078] The vitrifiable materials 25 cover the surface S of the glass bath 15, with a thickness that decreases from upstream to downstream as the melting process progresses. On the surface of the glass bath 15, the vitrifiable materials 25 form a demarcation line, more or less straight, characterized by the fact that the surface of the glass bath 15 no longer contains any vitrifiable materials downstream of said demarcation line.

[0079] Advantageously, the hybrid furnace 10 includes an immersed groove 30 through which the glass flows out of the furnace, said groove 30 opening into the downstream wall 14 of the furnace, in the vicinity of the hearth 22, so as to be in communication with the glass bath 15.

[0080] Advantageously, the hybrid furnace 10 includes means for evacuating fumes 40, such as at least one chimney (not shown), arranged in the first upstream third of the furnace of length L as illustrated in [Fig.1].

[0081] Preferably, said evacuation means 40 open into the interior of the furnace through the upstream wall 12, by an opening 42 placed in the vicinity of the vault 20. Alternatively, when the hybrid furnace 10 has only one niche 24 provided in the wall 12, said smoke evacuation means 40 are arranged for example in one and / or the other of the walls 14, 16, preferably in the first upstream third of the furnace.

[0082] In this first embodiment, the hybrid furnace 10 includes means for heating the vitrifiable materials 25 formed by burners 50 and electrodes 60 immersed in the glass bath 15, and includes at least some bubblers 70. Advantageously, the hybrid furnace 10 includes a submerged wall 80 disposed downstream of the electrodes 60 and said bubblers 70.

[0083] The hybrid furnace 10 includes burners 50, called aerial burners, which are capable of melting the vitrifiable materials 25 loaded into the furnace to obtain a bath 15 of glass.

[0084] The thermal energy released by the combustion carried out by the burners 50 is transmitted directly to the mixture of vitrifiable materials 25 and more generally to the glass bath 15 by radiation and convection, another part is transmitted by the vault 20 which, called hot vault for this reason, gives it back by radiation.

[0085] Preferably, burners 50 are arranged transversely on either side of the furnace. The number of burners 50 shown schematically—here, for example, twelve in total, six burners on each side—is purely illustrative and therefore not limiting. Thus, the number of burners 50 can vary depending, in particular, on the dimensions of the hybrid furnace 10.

[0086] Advantageously, the fuel energy is primarily used in the upstream burners 50, located in the immediate vicinity of the furnace area where the glassable materials are loaded (here via the niches 24), i.e., in the upstream half of the furnace, in order to achieve the melting process. By comparison, the downstream burners 50, located in the downstream half of the furnace, provide a hot spot on the surface of the glass bath and, moreover, maintain a roof temperature above a given level, notably to prevent any condensation.

[0087] Advantageously, burners 50 are arranged at least in the upstream half of the furnace of length L, as close as possible to the openings 26 through which the furnaces are loaded vitrifiable materials 25 in order to start the melting in the furnace as far upstream as possible from the exit.

[0088] As illustrated in [Fig.1], the burners 50 are arranged between the vault 20 and the surface S of the molten glass bath 15, opening into the inner wall of the walls 14 and 16.

[0089] Advantageously, the temperature measurement means 120 are suitable for measuring the vault temperature, in particular to enable the burners 50 to be controlled, for example by means of a furnace control unit (CU), in order to maintain a given temperature, preferably above 1100°C, more preferably 1150°C, or even at least 1200°C.

[0090] Preferably, the burners 50 are so-called transverse burners, commonly called so because of their transverse arrangement, that is to say perpendicular to the flow of the glass in the hybrid furnace 10, from upstream to downstream along the median axis A-A'.

[0091] The flame produced by combustion by the transverse burners 50 extends transversely so that the longitudinal distribution of temperatures can be adjusted by regulating the power of each of the burners 50.

[0092] The combustion carried out by the burners 50 can be obtained in a known manner by combining different types of fuel and oxidant, but the choice of which also has direct consequences in the carbon balance of the manufacture of the glass, namely the direct and indirect greenhouse gas emissions which are linked to the manufacture of the product, in particular carbon dioxide (CO2) emissions.

[0093] For combustion by burners 50, oxygen present in the air is generally used as the oxidant; this air may be enriched with oxygen to obtain superoxygenated air, or even almost pure oxygen is used in the specific case of oxycombustion. Generally, the fuel used is natural gas, that is to say, a fossil fuel.

[0094] In addition to the burners 50, the hybrid furnace 10 includes electrodes 60 which preferably are all mounted at the level of the hearth 22, generally through, so as to extend vertically in projection into the glass bath 15 from the horizontal surface formed by the hearth 22.

[0095] Alternatively, all or at least part of the electrodes are mounted at the level of the walls of the furnace, protruding - for example horizontally - so as to be immersed in the glass bath.

[0096] In this first embodiment, the electrodes 60 are also all arranged at the level of the sole 22 and longitudinally upstream of the bubblers 70.

[0097] Preferably, the electrodes 60 comprise at least one group 160 of electrodes comprising a first set 1601 of electrodes 60 and, upstream of said first set 1601, a second set 1602 of electrodes 60.

[0098] Preferably, the group 160 of electrodes 60 is positioned longitudinally downstream of the furnace zone for the vitrifiable materials 25, here downstream of the transversely opposed niches 24.

[0099] Advantageously, the first set 1601 of electrodes 60 is further configured to heat the glass homogeneously. Preferably, the first set 1601 of electrodes 60 comprises a number NI of electrodes between 8 and 14, for example a total of 12 electrodes forming a pad consisting here of three parallel rows, each row comprising four electrodes 60.

[0100] Preferably, the second set 1602 of electrodes 60 comprises at least one transverse row, more preferably two rows as illustrated in Figures 1 and 2. Preferably, the second set 1602 of electrodes 60 comprises a number N2 of electrodes between 4 and 9 per row, for example 6 electrodes forming a transverse row.

[0101] Advantageously, the second set 1602 of electrodes 60 comprising a number N2 of electrodes comprises two transverse rows, each comprising respectively 6 electrodes, for a total of N2 of 12 electrodes.

[0102] Advantageously, the second set 1602 of electrodes 60 is configured to form a barrier capable of acting on the convection loop C, in particular to oppose the downstream progression of the vitrifiable materials 25 present on the surface S of the glass bath 15.

[0103] The bubblers 70 are arranged at the hearth 22 so as to form at least one transverse row. Preferably, the hybrid furnace 10 comprises one transverse row of bubblers 70. The bubblers 70 constitute a system for injecting at least one gas, such as air or nitrogen, at the hearth 22, the bubbles 72 of which, illustrated in [Fig. 1], then create an upward movement of the glass.

[0104] Advantageously, said at least one row of bubblers 70 is arranged in the downstream half of the furnace, that is to say at more than 50% of the length L, preferably in the last downstream third of the furnace, more preferably in an area between 70% and 80% of said length L of the furnace.

[0105] Preferably, the hybrid furnace 10 includes cooling means (not shown) for the boilers 70, said cooling means using a cooling heat transfer fluid formed for example by water or by air.

[0106] Advantageously, the hybrid furnace 10 includes a submerged weir wall 80, generally made of refractory material. Preferably, the submerged wall 80 extends vertically from the base 22, over a given height less than the surface S of the glass bath 15, and transversely over the entire width of the furnace.

[0107] As illustrated in figures 1 and 2, the submerged wall 80 is arranged downstream of the bubblers 70. Preferably, the submerged wall 80 is arranged in the last downstream third of the hybrid furnace 10 of length L, in the vicinity of the furnace outlet constituted here by the submerged throat 30.

[0108] The submerged wall 80 serves to promote convection currents within the molten glass bath 15, such as the convection current C illustrated in [Fig. 1]. These convective movements create agitation which, by increasing the residence time of the glass, reduces the percentage of unmelted glass. Advantageously, the glass thus makes a number of rotations in the bath 15 following the convection current loop C before exiting the hybrid furnace 10 through the submerged throat 30.

[0109] In accordance with the invention and as explained in the preamble, studies (tests and / or simulations) have established that the bubblers 70 have consequences on the residence time of the glass and therefore the quality of the glass produced when seeking to increase the hybridization rate beyond a determined threshold value of electrical energy.

[0110] The glass manufacturing process according to the invention is also capable of being implemented in a hybrid furnace, in particular intended to supply a fiber-making unit, such as the hybrid furnace 10 illustrated in Figures 1 and 2 which has just been described.

[0111] Thus, the glass manufacturing process according to the invention is implemented in a hybrid furnace 10 comprising means for melting vitrifiable materials 25 formed respectively by burners 50 and electrodes 60 immersed in the glass bath 15, and comprising at least bubbling elements 70, preferably also an immersed wall 80.

[0112] According to the invention, said glass manufacturing process is characterized in that said bubbling 70s are selectively controlled, according to a determined threshold value corresponding to the share of electrical energy in the total energy used by said melting means 50, 60 for the melting of vitrifiable materials.

[0113] Advantageously, the bubblers 70 of the hybrid furnace 10 are selectively controlled according to at least: - a first mode (called active) of operation when the share of electrical energy in the total energy is below said threshold; - a second (so-called passive) mode of operation when the share of electrical energy in the total energy is greater than said threshold.

[0114] Advantageously, the hybrid oven 10 includes a control unit (CU) capable of selectively controlling at least said boilers 70 according to the share of electrical energy.

[0115] Preferably, the control unit (CU) is capable of controlling other elements of the hybrid furnace 10 such as the electricity to power the electrodes 60 determining the share of electrical energy or the share of fuel energy of the burners 50, in particular as a function of the vault temperature advantageously measured by the temperature measuring means 120.

[0116] The threshold value determining the selection of the operating mode of the bubblers 70 of the hybrid furnace 10 corresponds to a share of electrical energy of at least 15% of the total energy used by the melting means for the melting of the vitrifiable materials 25, for example to a share of electrical energy preferably between 15% and 25% of said total energy, or even more preferably between 15% and 20%.

[0117] Preferably, the first active operating mode of the bubblers 70 corresponds to a share of electrical energy between 5% and 10%, or even up to 15%, relative to the total energy.

[0118] Advantageously, the bubblers 70 are controlled in the first (active) mode so as to operate between 80% and 100% of their nominal capacity. For example, if the nominal flow capacity of one of the bubblers 70 is 10 liters per minute, then the flow rate is preferably between 8 and 10 liters per minute in the first active mode.

[0119] Fig. 1 represents more particularly the hybrid furnace 10 operating according to this first active mode of the bubblers 70 as illustrated in particular by the bubbles 72 traveling from the bottom of the glass bath 15 to the surface S, from the floor 22 comprising said bubblers 70.

[0120] In this first embodiment, the bubblers 70 are arranged just upstream of the submerged wall 80 so as to facilitate movements in the glass bath 15 along the convection belt C.

[0121] Advantageously, the bubblers 70 also have the function of removing the foam present on the surface of the glass bath 15 in order to improve the heat transfer from the flame to the glass.

[0122] Preferably, the second passive operating mode of the bubblers 70 corresponds to a share of electrical energy greater than 15%, preferably 20%, or even 25%, relative to the total energy used by said melting means 50, 60.

[0123] Preferably, the share of electrical energy in the total energy used by said melting means 50, 60 for the melting of vitrifiable materials 25 is however less than or equal to 50%, or even 60%, in this second passive mode of operation.

[0124] Advantageously, the bubblers 70 are controlled in the second (so-called passive) mode so as to operate between 0% (i.e., off) and 20%. For example, if the nominal flow capacity of one of the bubblers 70 is equal to 10 liters per minute, then the flow rate is preferably less than or equal to 2 liters per minute in the second passive mode.

[0125] Advantageously, the burners 50 are controlled to maintain a crown temperature above 1100°C, preferably 1150°C, or even above 1200°C. Such a crown temperature is maintained regardless of the proportion of electrical energy in the total energy, in other words, regardless of whether the boiling vortices 70 are in active or passive mode, but particularly when the hybridization rate increases.

[0126] Indeed, it is generally important, and even more so in certain cases, depending on the type of glass being manufactured, to ensure that a sufficient roof temperature is maintained despite a reduced use of burners 50 in favor of electrodes 60 as heating means, that is to say when the hybrid furnace 10 operates with a high hybridization rate, typically with an electrical energy share of 15% or 20% or even 25% up to 50% or even 60%, in other words an electrical share in the total energy corresponding to the selection of the second passive operating mode of the boilers 70.

[0127] More specifically, the increase in the hybridization rate is accompanied by a decrease in the roof temperature, and more generally in the temperature of the atmosphere inside the hybrid furnace 10, due to the reduced use of the overhead burners 50 in favor of the electrically powered submerged electrodes 60. However, the aforementioned studies have also established that the lifespan of the superstructure is severely threatened if the roof temperature falls below approximately 1100°C or even 1150°C, particularly due to the two phenomena described below.

[0128] On the one hand, a condensation phenomenon of certain chemical species can occur and lead to degradation. For example, a glass containing boron generates the volatilization of species such as sodium borate, which is likely to condense in areas with a temperature below 1050°C, potentially causing rapid degradation of the refractory material(s) constituting the superstructure.

[0129] Advantageously, maintaining a temperature greater than or equal to 1100°C or even 1150°C therefore prevents the appearance of cold zones on the surfaces of the vault and walls forming the superstructure, and subsequently the formation of liquid condensates of species such as sodium borate capable of causing degradations that can impact the lifespan of the hybrid furnace, or even the quality of the glass.

[0130] Advantageously, the oven 10 includes "drip edge" type means, that is to say at least one projecting element whose function is to divert condensation away from the face of the wall and thus prevent damage.

[0131] On the other hand, a contraction (or “shrinkage”) phenomenon is observed because certain corrosion-resistant refractory materials are used to construct the superstructure, in particular alumina-zirconia-silica (AZS) products with which a temperature below, for example, 1000°C causes a change in the crystallographic form of the zirconia present in said AZS material.

[0132] Advantageously, maintaining a temperature greater than or equal to 1100°C or even 1150°C therefore makes it possible to avoid creating contractions or shrinkages in the refractory blocks of the vault at the risk of destabilizing the mechanical resistance of the superstructure.

[0133] By comparison, in a hybrid furnace according to the prior art operating with an electrical supplement representing 5 to 15% of the total energy used during the melting stage of the vitrifiable materials, the temperature of the atmosphere is greater than 1200°C given the use of the burners 50, so that the aforementioned expansion and condensation phenomena do not occur.

[0134] During the studies carried out by the Applicant, it was established for a hybrid furnace 10 according to this first embodiment that, in the first active mode of the bubblers 70, the share of fuel energy in the total energy was such in relation to electrical energy that the demarcation line never extended longitudinally beyond the bubblers 70, remaining upstream of them.

[0135] On the other hand, when the bubbling 70s were operating according to the second passive mode, the demarcation line of the mat of vitrifiable materials 25 shifted downstream and, in so doing, moved closer to the outlet of the furnace, with consequences on the quality of the glass produced, in particular the presence of unmelted material in the glass.

[0136] In the second passive mode of operation, the bubblers 70 are stopped or deliver a very low flow rate of bubbles 72 so that there is no longer a barrier effect obtained, compared to the first active mode of operation of the bubblers 70 illustrated in [Fig.1].

[0137] This is also why the Applicant continued its studies which led to the design of a hybrid 10' furnace, said to be improved (by comparison with that of the first embodiment illustrated in Figures 1 and 2), corresponding to a second embodiment illustrated in Figures 3 and 4.

[0138] The following will be described, by comparison with the hybrid furnace 10 according to the first embodiment, the said improved hybrid furnace 10' corresponding to the second embodiment illustrated in figures 3 and 4.

[0139] Like the hybrid furnace 10, the hybrid furnace 10' for glassmaking is intended in particular but not exclusively to supply at least one fiber-making unit.

[0140] The hybrid furnace 10' includes means for melting vitrifiable materials 25 formed by burners 50 and electrodes 60 which, immersed in the glass bath 15, are arranged at the level of the hearth 22 upstream of bubbling 70 and a submerged wall 80.

[0141] In the improved hybrid furnace 10', said electrodes 60 comprise at least a first group 160 of electrodes and a second group 260 of electrodes, the second 260 group of electrodes being arranged between the bubblers 70 and the submerged wall 80. In other words, the electrodes 60 of this second group 260 are interposed between the bubblers 70 and the submerged wall 80 located downstream of said bubblers 70.

[0142] By comparison, the hybrid furnace 10 according to the first embodiment did not include such a second group 260 of electrodes but only a group 160 of electrodes like the electrodes 60 forming here the first group 160 of electrodes.

[0143] Preferably, the first group 160 of electrodes 60 of the hybrid furnace 10' is therefore analogous to the group of electrodes described previously for the hybrid furnace 10. Advantageously, the first group 160 of electrodes 60 comprises a first set 1601 of electrodes and a second set 1602 of electrodes.

[0144] Preferably, the electrical power is the same for the first set 1601 of electrodes and the second set 1602 of electrodes forming said first group 160 of electrodes 60 in the first active operating mode of the bubblers 70 corresponding to a low hybridization rate.

[0145] In the second passive operating mode of the bubblers 70 corresponding to a high hybridization rate, the electrical power is supplied in priority to the second set 1602 of electrodes of the first group 160 of electrodes 60 as well as to the second group 260 of electrodes, in particular with respect to the first set 1601 of electrodes 60.

[0146] Preferably, the electrodes 60 of the second set 1602 of electrodes of the first group 160 of electrodes and of the second group 260 of electrodes have a diameter greater than the usual diameter, for example a diameter of 101 mm (or 4 inches) against a diameter of 76 mm (or 3 inches) usually, so as to be able to increase the surface area of ​​the electrodes and advantageously preserve the life of said electrodes 60 (in particular reduction of corrosion).

[0147] Preferably, the second set 1602 of electrodes comprises a single row of electrodes 60, whereas, by comparison, the set of the first embodiment preferably comprised two rows of electrodes. Alternatively, the second set 1602 of electrodes comprises two rows of electrodes 60, as in the first embodiment.

[0148] Advantageously, the first set 1601 of electrodes 60 is further configured to heat the glass homogeneously. Preferably, the first set 1601 of electrodes 60 comprises a number NI of electrodes between 8 and 14, for example a total of 12 electrodes forming a pad consisting here of three parallel rows, each row comprising four electrodes 60.

[0149] Preferably, the second set 1602 of electrodes 60 comprises a transverse row as illustrated in Figures 3 and 4. Preferably, the second set 1602 of electrodes 60 comprises a number N2 of electrodes between 4 and 9 per row, for example 6 electrodes forming said transverse row.

[0150] Advantageously, the second set 1602 of electrodes 60 is configured to form a barrier, called the first barrier, capable of acting on the convection loop C, in particular to oppose the downstream progression of the vitrifiable materials 25 present on the surface S of the glass bath 15.

[0151] Advantageously, the electrodes 60 of the second group 260 are arranged along at least one transverse row of electrodes, preferably here a single transverse row, to form a barrier, called a second barrier, capable of acting on the convection loop C, in particular to oppose the downstream progression of the vitrifiable materials 25 present on the surface S of the glass bath 15.

[0152] Advantageously, the second group 260 of electrodes is selectively supplied with electricity according to said threshold value determined corresponding to the share of electrical energy in the total energy used by said melting means for the melting of vitrifiable materials.

[0153] Advantageously, the second group 260 of electrodes is supplied only when the bubblers 70 operate according to a second (so-called passive) mode of operation and then form said second barrier.

[0154] When the hybrid furnace 10' operates with a low hybridization rate, i.e. below said threshold value, for example with a share of electrical energy between 5 and 10% of the total energy, typically therefore less than 15 or 25%, the barrier effect promoting convection (and therefore residence time) is obtained thanks to the bubblers 70 which are then active.

[0155] When the hybrid furnace 10' operates with a high hybridization rate, beyond said threshold value, with an electrical energy share of at least 15% of the total energy, the bubblers 70 are passive and no longer provide a barrier effect. Preferably, the share of electrical energy is for example at least between 15% and 20% or even between 15% and 25% and said share of electrical energy is also preferably less than or equal to 50% or even 60% of the total energy.

[0156] Consequently, the barrier effect promoting convection (and therefore residence time) is obtained by means of electrodes 60 here twice compared to the first embodiment, i.e. a double effect.

[0157] Advantageously, said barrier effect is respectively obtained by the second set 1602 of the first group 160 of electrodes forming said first barrier and by the second group 260 of electrodes which, being selectively supplied, form said second barrier.

[0158] Advantageously, the second group 260 of electrodes is arranged in the downstream half of the hybrid furnace 10' having a length L, or at more than 50% of the length L, preferably in the last downstream third of the furnace.

[0159] Preferably, the second group 260 of electrodes is arranged in an area between 80% and 90% of said length L, here upstream of the submerged wall 80, before the outlet of the furnace.

[0160] Preferably, the second set 1602 of the first group 160 of electrodes forming said first barrier and the second group 260 of electrodes forming said second barrier are electrically powered via the control unit (CU) so as to obtain said barrier effect.

[0161] As previously indicated, the hybrid furnace 10 or 10' are intended in particular, but not exclusively, to supply a fiber-making unit for the transformation into fibers of said manufactured glass.

[0162] Another object of the present invention relates to a process for preparing glass fibers such as glass wool, rock wool or textile glass yarns, comprising the glass manufacturing process according to the invention, followed by the transformation into fiber by a fiber-making unit of said manufactured glass.

[0163] The present invention thus proposes a method for manufacturing glass in a hybrid furnace, in particular intended to supply at least one fiber-making unit, comprising means for melting vitrifiable materials formed by burners and electrodes immersed in the glass bath, and comprising at least some bubbling elements, characterized in that at least a part of said bubbling elements is selectively controlled, according to a determined threshold value corresponding to the share of electrical energy in the total energy used by said melting means, respectively according to at least a first mode (called active) of operation when the share of electrical energy is less than said threshold; and a second mode (called passive) of operation when the share of electrical energy is greater than said threshold.

[0164] Preferably, the hybrid furnace includes at least one submerged wall 80 or any other equivalent means forming an obstacle.

[0165] According to a first embodiment, the glass manufacturing process, in particular intended to supply a fiber unit, in a hybrid furnace comprising means for melting vitrifiable materials formed by burners and electrodes immersed in the glass bath, and at least bubbling elements arranged upstream of a submerged wall, in which said electrodes comprise at least one (first) group of electrodes which are arranged upstream of said bubbling elements, is characterized in that said bubbling elements are selectively controlled according to the teachings of the invention.

[0166] According to a second embodiment, the glass manufacturing process, in particular intended to supply a fiber unit, in a hybrid furnace comprising means for melting vitrifiable materials formed by burners and electrodes immersed in the glass bath, and at least bubbling elements arranged upstream of a submerged wall, in which said electrodes comprise at least a first group of electrodes arranged upstream of said bubbling elements and at least a second group of electrodes arranged between said bubbling elements and the submerged wall, is characterized in that said bubbling elements are selectively controlled according to the teachings of the invention.

Claims

Demands

1. A method for manufacturing glass in a hybrid furnace (10, 10'), in particular intended to supply at least one fiber-making unit, comprising means for melting (50, 60) of vitrifiable materials (25) formed by burners (50) and electrodes (60) immersed in the glass bath (15), and comprising at least some bubbling elements (70) and preferably a submerged wall (80), characterized in that at least a part of said bubbling elements (70) is selectively controlled, according to a determined threshold value corresponding to the share of electrical energy in the total energy used by said melting elements (50, 60), respectively according to at least: - a first mode (called active) of operation when the share of electrical energy is less than said threshold; - a second mode (called passive) of operation when the share of electrical energy is greater than said threshold.

2. A glass manufacturing process according to claim 1, characterized in that the threshold value determining the selection of the operating mode of the bubblers (70) corresponds to a share of electrical energy of at least 15% of said total energy, preferably said threshold value is between 15% and 25% of said total energy, more preferably between 15% and 20% of said total energy.

3. A glass manufacturing process according to claim 1 or 2, characterized in that at least a part of said bubblers (70) is controlled in the first mode (called active) so as to operate between 80% and 100% of their nominal capacity, for example with a flow rate of between 5 and 20 liters per minute, preferably with a flow rate of between 8 and 10 liters per minute.

4. A glass manufacturing process according to any one of claims 1 to 3, characterized in that at least a part of said bubblers (70) is controlled in the second mode (called passive) so as to operate between 0% and 20% of their nominal capacity, preferably with a flow rate of less than or equal to 2 liters per minute.

5. A method for manufacturing glass according to any one of claims 1 to 4, characterized in that the share of electrical energy in the total energy used by said melting means (50, 60) for melting vitrifiable materials is less than or equal to 50%, or even 60%.

6. A method for manufacturing glass according to any one of claims 1 to 5, characterized in that the burners (50) are controlled to maintain a dome temperature that is greater than 1100°C, preferably greater than 1150°C.

7. A method for manufacturing glass according to any one of the preceding claims, wherein said bubblers (70) of the hybrid furnace are positioned so as to form at least one transverse row, characterized in that said bubblers (70) comprise at least two rows which are capable of being controlled independently of each other, in particular capable of being controlled differently from each other.

8. A method for manufacturing glass in a hybrid furnace (10) comprising a submerged wall (80) upstream of which at least said bubblers (70) are arranged and in which said electrodes (60) comprise at least one group (160) of electrodes which are arranged upstream of said bubblers (70), characterized in that said bubblers (70) are selectively controlled according to any one of claims 1 to 7.

9. A method for manufacturing glass in a hybrid furnace (10') comprising a submerged wall (80) upstream of which at least said bubblers (70) are arranged and in which said electrodes (60) comprise at least a first group (160) of electrodes arranged upstream of said bubblers (70) and at least a second group (260) of electrodes arranged between said bubblers (70) and the submerged wall (80), characterized in that said bubblers (70) are selectively controlled according to any one of claims 1 to 7.

10. A glass manufacturing process according to claim 9, characterized in that the second group (260) of electrodes is selectively supplied with electricity according to said determined threshold value, the second group (260) of electrodes being supplied only when the bubblers (70) operate according to a second (so-called passive) mode of operation.

11. A process for preparing glass fibers such as glass wool, rock wool or textile glass yarns, comprising the process for manufacturing glass according to any one of the preceding claims, followed by transformation into fiber by at least one fiber-making unit of said manufactured glass.

12. Hybrid furnace (10, 10') for the manufacture of glass, said hybrid furnace (10, 10') comprising means for melting (50, 60) of vitrifiable materials formed by burners (50) and electrodes (60) immersed in the glass bath (15), said electrodes (60) forming at least one group (160) of electrodes arranged upstream of bubblers (70) and preferably of a submerged wall (80), characterized in that the furnace comprises at least one control unit (CU) capable of selectively controlling at least a part of said bubblers (70) according to a determined threshold value corresponding to the share of electrical energy in the total energy implemented by said melting means, respectively according to at least: - a first mode (called active) of operation when the share of electrical energy is less than said threshold; - a second (so-called passive) mode of operation when the share of electrical energy is greater than said threshold.

13. Hybrid furnace (10') according to claim 12, wherein said at least electrode group comprises a first group (160) of electrodes arranged upstream of bubblers (70) and a submerged wall (80), said furnace being characterized in that at least a second group (260) of electrodes is arranged between the bubblers (70) and said submerged wall (80).

14. Hybrid furnace (10') according to claim 13, characterized in that the electrodes (60) of the second group (260) are arranged along at least one transverse row of electrodes, preferably a single transverse row, to form a barrier, called second barrier.

15. Hybrid furnace (10') according to claim 14, characterized in that the electrodes (60) of the second group (260) are arranged in the downstream half of the furnace having a length L, i.e. at more than 50% of the length L, preferably in the last downstream third of the furnace having a length L, more preferably in an area between 80% and 90% of said length L.

16. Hybrid furnace according to any one of claims 11 to 15, characterized in that the bubblers (70) are arranged so as to form at least one transverse row, preferably a transverse row, said at least one row of bubblers being arranged in the downstream half of the furnace having a length L, that is to say at more than 50% of the length L, preferably in the last downstream third of the furnace, more preferably in an area between 70% and 80% of said length L.

17. Hybrid furnace according to any one of claims 11 to 16, characterized in that the group (160) of electrodes, referred to as the first group, comprises a first set (1601) of electrodes arranged upstream of a second set (1602) of electrodes, said second set (1602) of electrodes comprising at least one transverse row to form a barrier, referred to as the first barrier.

18. Hybrid furnace according to claim 17, characterized in that the first set (1601) of electrodes comprises a number NI of electrodes between 8 and 14, for example 12 electrodes forming a pad, and in that the second set (1602) of electrodes comprises a number N2 of electrodes between 4 and 9 per row, for example 6 electrodes forming a transverse row.

19. Hybrid furnace according to any one of claims 12 to 18, characterized in that the electrodes (60) are arranged at the level of a floor (22) of the furnace.

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