Hybrid glass production furnace with energy flexibility and method for producing glass

Abstract

The invention relates to a hybrid furnace (10) for producing glass, in particular for supplying a float unit, the hybrid furnace (10) having a longitudinal axis (A-A') comprising: - at least one electric melting zone (110) comprising electrodes (115) which is suitable for being supplied with a vitrifiable mixture by a first charging device (610); - a flame melting zone (120) comprising at least overhead burners (125) which is suitable for being supplied with a vitrifiable mixture by a second charging device (620), separate from the at least one first charging device (610), wherein the at least one electric melting zone (110) and the flame melting zone (120), which are arranged in series, are configured to be able to operate independently of one another so as to allow selective use of either or both of the melting zones (110, 120), thereby granting the furnace (10) energy flexibility.

Description

[0001] HYDRIDE GLASS MAKING FURNACE WITH ENERGY FLEXIBILITY AND GLASS MAKING METHOD

[0002] TECH NIC AREA OF THE I NVENTION

[0003] The invention relates to a hybrid glass manufacturing furnace having in particular energy flexibility and a glass manufacturing method implemented in such a hybrid furnace.

[0004] The invention relates more particularly to a hybrid glass manufacturing furnace comprising in particular at least one electric melting zone and one flame melting zone which, independent of each other, are capable of being used selectively, jointly or not, thanks to which the furnace has energy flexibility by making it possible to choose at least one energy source such as electricity and / or a fuel for melting the vitrifiable mixture in order to obtain molten glass which then flows into a refining zone with two convection belts so as to obtain, in suitable quantity, high-quality glass.

[0005] Indeed, the hybrid furnace according to the invention is not only capable of allowing energy flexibility but also of delivering high-quality glass with less than 0.1 bubble per liter and this with a draw of at least 400 tons per day, preferably between 600 and 900 tons per day, or even 1000 tons per day or more, in particular to supply a glass float unit on a bath of molten metal (or "float" in English) intended to manufacture flat glass.

[0006] The invention also relates to a method for manufacturing glass implemented in such a hybrid furnace comprising at least one step of melting a vitrifiable mixture carried out in at least one electric melting zone and / or one flame melting zone of the hybrid furnace.

[0007] STATE OF THE ART

[0008] Various examples of furnace designs for glass production are known from the state of the art, which depend in particular on the product to be produced, i.e. the final shaping of the glass. Thus, different furnace designs are distinguished depending on whether the intended production concerns glass fibers, the industrial shaping of hollow glass or that of flat glass.

[0009] One of the industrial challenges in the design of glass furnaces is to be able to obtain glass whose quality requirements depend on the product. In this respect, the production of flat glass is comparatively one of the most demanding.

[0010] Produced in very large quantities, flat glass is used in many applications due to its versatility, particularly widely used in the electronics (flat screens) or construction and automotive sectors in which this glass can be transformed using a wide variety of techniques (bending, tempering, etc.), thus constituting a basic glass for a whole range of glass products.

[0011] In proportion to the issues of both quality and quantity, the present invention particularly aims at the manufacture of glass for the industrial forming of such flat glass, which glass is conventionally obtained by means of a unit for floating the glass on a bath of molten metal, generally tin, which is why such flat glass is also called float glass or "float" according to the English term.

[0012] For the manufacture of flat glass, it is expected to be possible to feed the float unit with high quality glass, i.e. glass containing as few unmelted particles and bubbles as possible, generally glass with less than 0.5 bubbles / litre.

[0013] Indeed, the quality of the glass is determined in particular, but not exclusively, by the number of bubbles present in the glass, which is expressed in "bubbles per liter". Thus, the quality of a glass is considered to be higher when the number of bubbles per liter present in the glass is particularly low, or even tiny.

[0014] Furthermore, it should be remembered that the presence of bubbles (or gas defects) in the glass is inherent in the glass manufacturing process, in the production process of which three successive stages or phases are generally distinguished: melting, refining and homogenization and thermal conditioning of the glass.

[0015] The presence of bubbles in the glass results in fact from the melting stage during which a vitrifiable mixture, also called "composition", is melted. The vitrifiable mixture is made up of raw materials including, for example, a mixture of sand, limestone (calcium carbonate), sodium carbonate, dolomite for the manufacture of soda-lime glass (the glass most used for the manufacture of flat glass), and to which cullet (also called cullet) made up of glass debris is advantageously added in order to promote melting.

[0016] The vitrifiable mixture is transformed into a liquid mass in which even the least miscible particles dissolve, i.e. those richest in silicon dioxide or silica (SiC>2) and poor in sodium oxide (Na2O).

[0017] Sodium carbonate (Na2COs) begins to react with sand grains at 775°C, releasing bubbles of carbon dioxide (CO2) in a liquid that becomes increasingly viscous as the carbonate transforms into silicate. Similarly, the transformation of limestone grains into lime and the decomposition of dolomite also cause the emission of carbon dioxide (CO2).

[0018] The melting stage is complete when there are no more solid particles in the molten glass liquid, which has become very viscous but which, at this stage of the manufacturing process, is then filled with air and gas bubbles.

[0019] The refining and homogenization step then allows the elimination of said bubbles present in the molten glass. As is known, "refining agents" are advantageously used during this step, i.e. substances in low concentration which, by decomposing at the melting temperature of the bath, provide gases which cause the bubbles to swell in order to accelerate their rise towards the surface of the glass.

[0020] The thermal conditioning stage of the manufacturing process then makes it possible to lower the temperature of the glass since, at the start of the shaping operation, the viscosity of the glass must generally be at least ten times higher than during refining.

[0021] There is obviously a correspondence between each of the stages of glass manufacturing which have just been described and the structure of a furnace intended for their implementation.

[0022] Generally, such a furnace for the manufacture of glass thus comprises successively a melting zone in which the transformation by melting of the vitrifiable mixture into a glass bath takes place, then a refining and homogenization zone to eliminate bubbles from the glass and finally a thermal conditioning zone used to cool the glass so as to bring it to the forming temperature, well below the temperatures experienced by the glass during its production.

[0023] It should be noted in particular from the glass production process that has just been recalled that the melting stage is accompanied by the emission of carbon dioxide (CO2), one of the main greenhouse gases involved in climate change.

[0024] This is why we are seeking to use an ever-increasing proportion of cullet in order to reduce these direct carbon dioxide (CO2) emissions, as well as indirect carbon dioxide (CO2) emissions linked to the raw materials of the vitrifiable mixture.

[0025] Indeed, apart from the manufacture of high-quality glass, as well as the industrial challenges of high productivity with the lowest possible construction and operating costs for furnaces, one of the other major challenges that the glass industry currently faces is ecological, namely the need to find solutions to reduce the carbon footprint (in English "CO2 footprint") linked to the glass production process.

[0026] To achieve a carbon neutrality objective, a holistic approach to the process is favored by seeking to act on multiple levers to reduce both direct emissions during manufacturing and indirect emissions, as well as emissions upstream and downstream in the value chain, for example those linked to the transport of materials upstream and then of the product downstream. Therefore, the multiple levers include product design and material composition, improving the energy efficiency of industrial processes, using renewable and decarbonized energy, collaborating with raw material suppliers and transporters to reduce their emissions, and finally, exploring technologies for capturing and sequestering residual emissions.

[0027] In direct emissions, in addition to those inherent in the glass production process mentioned above, the type of energy(s) used, particularly for the high-temperature melting stage (over 1500°C), represents the largest share in the carbon footprint of the glass production process since it is generally a fossil fuel, most often natural gas, or even petroleum products such as fuel oil.

[0028] Therefore, the search for new furnace designs must not only meet industrial challenges related to glass quality but also reduce the carbon footprint of the glass production process, both direct and indirect carbon dioxide (CO2) emissions, and this in particular by reducing the use of fossil energy(s).

[0029] Glass production is carried out in furnaces that have continued to evolve from the first pot (or crucible) furnaces to the Siemens furnace, which is usually considered the ancestor of today's large continuous casting glass furnaces, like the cross-burner furnaces that can produce up to 1,200 tonnes of float glass per day.

[0030] The choice of energy used for melting thus leads to distinguishing mainly two major designs of furnace for glass manufacturing, respectively flame furnaces and electric furnaces.

[0031] According to the first design, flame furnaces generally use fossil fuels, especially 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.

[0032] The aforementioned cross-burner furnaces are an example of a furnace according to this first design and are widely used to supply molten glass to a float unit intended to manufacture flat glass.

[0033] According to the second concept, electric furnaces are furnaces in which thermal energy is produced by the Joule effect in the mass of molten glass.

[0034] Indeed, an insulating substance at room temperature, glass becomes electrically conductive at high temperature so that we can consider using the Joule effect within the glass melts themselves to heat them.

[0035] However, electric furnaces are used, for example, for the production of special glasses such as fluorine opal glass or lead crystal, or are commonly used for the production of glass fibers for thermal insulation.

[0036] Indeed, it is commonly accepted by those skilled in the art that such electric furnaces are not capable of supplying, either in quantity or, above all, in quality of glass (as a reminder, less than 0.5 bubbles per litre), a glass float unit on a bath of molten metal intended for the manufacture of flat glass.

[0037] The state-of-the-art electric furnaces known to the Applicant are at most capable of delivering a run of 200 to 250 tonnes per day of glass which has at best a few hundred bubbles per litre, more generally a few thousand, which may possibly be suitable for forming hollow glass, typically bottles, but in no way for the manufacture of flat glass and consequently the supply of a float unit.

[0038] This is why flame furnaces (like cross-burner furnaces) remain today the only furnaces capable of supplying such a glass float unit.

[0039] However, flame furnaces rely on the use of fossil fuels, mainly natural gas, for fuel, so their carbon footprint is not very compatible with the objectives of reducing carbon dioxide (CO2) emissions, or the carbon footprint of the glassmaking process.

[0040] To complete the presentation of furnace designs for glass manufacturing according to the state of the art, we will mention a third furnace design, which has recently undergone developments to address in particular the ecological challenge of reducing carbon dioxide (CO2) emissions.

[0041] This third furnace design is based on a flame furnace but uses additional electric heating, in particular to temporarily increase the furnace's production or to improve the quality of the glass.

[0042] Therefore, such ovens are still called "flame ovens with electrical support".

[0043] Ovens according to this third design thus combine several energy sources, respectively fossil and electric, and are for this reason also called "hybrid" ovens.

[0044] The addition of additional electric heating 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.

[0045] However, the operation of such a hybrid furnace still relies primarily on the use of a fossil fuel, typically gas, so the impact ultimately achieved on improving the carbon footprint of the glassmaking process remains limited. Indeed, electricity is only used here as a supplement, so its impact is proportional.

[0046] Furthermore, to effectively improve the carbon footprint, the electricity used must still be so-called "green" electricity, i.e. electricity produced from renewable and decarbonized energy sources.

[0047] It should be noted that the previous remark on electricity applies equally to fuels such as bio-methane or hydrogen which could be used as a replacement for natural gas in burners.

[0048] While improving the carbon footprint in the glass production process is a crucial issue, as demonstrated by the commitments of market players to produce "zero carbon" glass, controlling manufacturing costs also remains a major concern.

[0049] However, since glass manufacturing is particularly energy-intensive, particularly the stage of melting the vitrifiable mixture, the choice of energy used in a glass manufacturing furnace ultimately proves to be a determining factor both economically and ecologically.

[0050] Generally speaking, energy costs follow the law of the market, varying according to supply and demand, although it should be noted that depending on the type of energy (gas, oil, etc.) used directly or transformed into electricity, resources are unevenly distributed across the planet, so that geopolitical issues such as war are likely to have a strong impact on them.

[0051] It will therefore be understood that for the design of new furnaces for glass manufacturing, energy choices are of great importance and come up against many uncertainties, in particular economic risks linked to energy costs, or even their availability in sufficient quantity, in particular to be able to meet the ecological challenges linked to the manufacture of so-called "zero carbon" glass.

[0052] The aim of the invention is furthermore to propose a new design of furnace for the manufacture of glass making it possible to limit the economic risks linked to the energy choice, while being able to deliver a glass which is of high quality on the one hand and in the required quantity on the other hand, in particular capable of supplying a glass float unit intended to manufacture flat glass, and making it possible to obtain a reduction in carbon dioxide (CO2) emissions linked to the glass production process.

[0053] BRIEF SUMMARY OF THE INVENTION

[0054] For this purpose, the invention proposes a hybrid furnace for the manufacture of glass, in particular for supplying a glass float unit on a bath of molten metal, said hybrid furnace with a longitudinal axis comprising:

[0055] - at least one electrical melting zone which is capable of being supplied with vitrifiable mixture by at least one first charging device and which comprises electrodes for melting said vitrifiable mixture;

[0056] - a flame melting zone which, separate from said at least one electric melting zone, is capable of being supplied with vitrifiable mixture by at least one second charging device and which comprises at least overhead burners for melting said vitrifiable mixture, said overhead burners being arranged above the surface of the molten glass, in which said at least one electric melting zone and said flame melting zone are arranged in series so that the molten glass produced by one of said melting zones located upstream is capable of flowing into the other of said melting zones located downstream and in which said at least one electric melting zone and said flame melting zone are configured to be able to operate independently of one another so as to allow selective use of one and / or the other of said melting zones in order to give the furnace energy flexibility,

[0057] - a refining zone for the molten glass delivered by said at least one electric melting zone and / or said flame melting zone, said refining zone being configured to comprise a first convection belt and a second convection belt; and

[0058] - a glass cooling zone comprising a conditioning basin which is traversed by the second convection belt and which is connected to at least one glass flow channel.

[0059] Advantageously, the hybrid furnace according to the invention is characterized by the fact of comprising at least two melting zones which, distinct and independent of each other, are capable of operating selectively with a different energy source.

[0060] Advantageously, the hybrid furnace comprises respectively at least a first melting zone using a first energy and a second melting zone using a second energy source which is different from the first energy source, whereby it is possible to selectively use a first energy and / or a second energy for the benefit in particular of energy flexibility for the manufacture of glass.

[0061] Preferably, the first energy is for example electricity and the second energy is a fuel.

[0062] Advantageously, the hybrid furnace design according to the invention allows for total energy flexibility, with the possibility of using for the melting of the vitrifiable mixture either only one of said at least one electric melting zone and flame melting zone of the furnace, or jointly said electric and flame melting zones in configurable proportions.

[0063] Thus, the hybrid furnace offers several operating modes in terms of the choice of energy used for melting the vitrifiable mixture, or more generally a multi-mode type of operation, the operating mode of the selected hybrid furnace being able to be determined according to at least one selection parameter comprising one or more criteria.

[0064] For each glass production, we may at a given moment want to prioritize at least one criterion, or even seek the best compromise according to several criteria such as, for example, economic, ecological or even technical criteria.

[0065] The economic criterion of the cost of energy is therefore only one of the criteria likely to be taken into account during the choice, in fact an ecological criterion considering in particular the carbon footprint (CO2) of the energy used, or even one or more technical criteria are also.

[0066] When said electric and flame melting zones are used together, there is again flexibility since the proportion of molten glass capable of being produced by each is freely configurable, in particular by acting on the associated charging devices and the heating means for melting, namely the electrodes and the overhead burners.

[0067] Thus, the electricity used to power the electrodes and the fuel used to power the overhead burners may or may not be used in equal parts, for example in a ratio of 50 / 50 (i.e. 50% each). Electricity may also be more important than fuel (or vice versa), for example with a ratio of 80 / 20 (i.e. 80% electricity and 20% fuel) or any other ratio such as 70 / 30 or 60 / 40.

[0068] In such an operating mode, called hybrid, the charging devices respectively associated with each of said electric and flame melting zones then feed them with vitrifiable mixture in proportion, selectively, and in doing so the charging devices also participate in obtaining the energy flexibility of a hybrid furnace according to the invention. In a hybrid furnace according to the invention, the maximum draft of said at least one electric melting zone and likewise that of the flame melting zone are determined at the outset by construction and can each be dimensioned to be able to deliver a draft which is equal to the nominal draft desired for the furnace and this in order to be able to achieve this nominal draft even when only one of said melting zones is used, that is to say a single energy for melting, electricity or fuel.

[0069] However, it is also possible to dimension at least one of said melting zones of the furnace so that its maximum draft is less than the nominal draft of the furnace, thereby benefiting from a reduction in the dimensions of said at least one melting zone. In this case, the nominal draft of the furnace can only be achieved by jointly using the electric and flame melting zones, or by using the other melting zone if the latter is dimensioned to be able to deliver a maximum draft equal to the nominal draft of the furnace.

[0070] Thanks to the design of the hybrid furnace according to the invention, offering such multi-mode operation guaranteeing energy flexibility, it is possible to significantly reduce the risks associated with the choice of a given energy whose costs and availability are likely to vary greatly on the markets, in particular depending on the supply / demand ratio, throughout the entire operating life of the furnace.

[0071] By comparison with the invention, it will be understood that in a furnace according to the state of the art in which the melting of the vitrifiable mixture is obtained with a single energy, typically a fuel for the first design or electricity for the second design, there is no energy flexibility.

[0072] Thus, in the event of a very significant increase in the cost of the energy used for melting or even its unavailability, the consequences can go as far as calling into question the production of glass and leading to a shutdown of the furnace.

[0073] This also applies to a hybrid furnace according to the third design, although fuel and electricity (as a backup) are used, as the production of molten glass cannot be achieved with a single energy source in such a furnace, especially not with electricity alone. Generally speaking, it should be remembered that the construction of a furnace for the production of glass is a very expensive investment and that the operating life of such a furnace to amortize it is long, generally more than twenty years, this also necessarily having an impact on the choices made when building a furnace.

[0074] However, the energy flexibility offered by a hybrid furnace according to the invention is only one of the advantages since the design of the furnace also makes it possible to obtain very high quality glass and, moreover, produced in the quantity required to be able to supply a float unit intended to manufacture flat glass, which is by far the most demanding application.

[0075] The arrangement in series with respect to each other of said at least one electric melting zone and the flame melting zone advantageously promotes the mixing of the molten glass delivered by each when said zones are used jointly in the hybrid operating mode.

[0076] Thanks to the arrangement in series of said at least one electric melting zone and said flame melting zone, the molten glass produced by one of said melting zones located upstream is in fact likely to flow into the other of said melting zones located downstream, which promotes the mixing of the glass, in particular due to the temperature of the glass present in each of said melting zones.

[0077] In addition to the said serial arrangement, the two glass convection belts also contribute to obtaining very high quality glass, with less than 0.1 bubbles per liter, in particular the first convection belt which extends into the flame melting zone and the refining zone.

[0078] Advantageously, the hybrid furnace comprises a corset connecting together said at least one electric melting zone and said flame melting zone.

[0079] In a hybrid furnace according to the invention, thanks to said glass anti-return separation device advantageously arranged in the corset, no convection belt or glass recirculation loop extends from the flame melting zone to the electric melting zone, whether or not the electric melting zone is used. By comparison, a submerged groove connecting an electric melting zone to a flame melting zone would not be able to provide such a glass anti-return function in a furnace. Indeed, a glass return current necessarily exists in a groove, in particular due to the wear of the materials.

[0080] Furthermore, the glass flowing in a groove is not in contact with the atmosphere so that it is further not susceptible to being cooled in a controlled and variable manner at the surface, in particular by cooling means such as an air circulation cooling device.

[0081] A corset advantageously allows the surface evacuation of bubbles present in the glass, unlike a groove in which the bubbles are trapped in the glass. In addition, the contact of the bubbles with the refractories of the groove causes accelerated corrosion at the interface, resulting in premature wear of the groove and "chemical pollution" of the glass by the materials forming the refractories.

[0082] Compared to a throat whose section is limited by construction, the corset also allows the glass to flow with a pull capable of feeding a float unit.

[0083] Compared to a throat, the glass leaving a corset has a higher temperature because it is glass located near the surface of the bath in the upstream melting zone from which it comes, as opposed to the glass present at the floor. However, due to the air access to the glass, a corset allows for cooling of the glass.

[0084] This cooling of the glass can be passive (mainly by radiation), or even active (with cooling means), whereby the temperature of the glass flowing in the corset is controlled, in particular with a view to obtaining an optimal mixture with the glass present in the melting zone located downstream of the corset. Cooling of the glass as obtained in the corset (with or without cooling means) is also particularly advantageous when the glass is produced by electric melting because the molten glass generally has a high temperature (compared to that of flame melting), a glass temperature which it is therefore sometimes appropriate to reduce.

[0085] Other advantageous characteristics of the invention are in particular the subject of the dependent claims.

[0086] BRIEF DESCRIPTION OF THE FIGURES

[0087] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0088] - Figure 1 is a sectional view through a vertical plane along the longitudinal axis A-A' of the furnace which represents a hybrid furnace for the manufacture of glass according to a first embodiment of the invention comprising an electric melting zone and an independent flame melting zone and which illustrates said electric melting zone connected by a corset to the flame melting zone which is connected to a refining zone comprising a first convection belt and a second convection belt itself then connected to a cooling zone traversed by said second convection belt;

[0089] - Figure 2 is a sectional view through a horizontal plane which represents the furnace according to the first embodiment seen from above and which further illustrates a first charging device capable of supplying the electric melting zone and a second charging device capable of supplying the flame melting zone, which melting zones are connected to each other by the corset comprising a “non-return” separation device configured to prevent a return of the molten glass from the flame melting zone to the electric melting zone;

[0090] - figure 3 is a sectional view which shows in detail the corset of the hybrid furnace according to figure 1 and which illustrates a preferred embodiment of said “non-return” glass separation device constituted by an elevation of the base of the corset;

[0091] - figure 4 is a sectional view which, similar to figure 3, represents in detail the corset of the hybrid furnace and which illustrates another example of embodiment of said “non-return” glass separation device comprising a movable barrier and an elevation of the bottom of the corset

[0092] - Figure 5 is a sectional view similar to Figure 2 which represents the furnace according to the first embodiment in a first mode of operation with electric melting and which further illustrates the electric melting zone covered with a layer of vitrifiable mixture retained downstream by blocking means and the melting of which to obtain the molten glass is carried out solely in said zone with electricity for energy;

[0093] - Figure 6 is a sectional view similar to Figure 2 which represents the furnace according to the first embodiment in a second hybrid operating mode in which the melting of the vitrifiable mixture is carried out jointly in the electric melting zone and in the flame melting zone, each supplied by separate charging devices, and which illustrates the electric melting zone covered with a layer of vitrifiable mixture introduced by a first charging device and the flame melting zone covered with a layer of vitrifiable mixture introduced by a second charging device comprising two charging units;

[0094] - Figure 7 is a sectional view similar to Figure 2 which represents the furnace according to the first embodiment in a third flame melting mode of operation and which further illustrates the flame melting zone covered with a layer of vitrifiable mixture and the melting of which to obtain the molten glass is carried out by combustion in said zone provided with burners with a fuel for energy;

[0095] - Figure 8 is a sectional view through a vertical plane along the longitudinal axis A-A' of the furnace which represents a hybrid furnace for the manufacture of glass according to a second embodiment of the invention comprising two electric melting zones and a flame melting zone and which illustrates said flame melting zone to which are respectively connected a first electric melting zone and a second electric melting zone arranged transversely, said flame melting zone being connected to a refining zone which, comprising a first convection belt and a second convection belt, is itself connected to a cooling zone traversed by said second convection belt;

[0096] - Figure 9 is a sectional view through a horizontal plane which represents the hybrid furnace according to the second embodiment seen from above and which further illustrates the first electric melting zone and the second electric melting zone arranged transversely on either side of the flame melting zone to which each of said zones is connected by a corset;

[0097] - figure 10 is a sectional view through a vertical plane along a transverse axis B-B' shown in figure 9 which represents the hybrid furnace according to the second embodiment and which illustrates the first electric melting zone and the second electric melting zone respectively connected transversely to said flame melting zone by a first corset and by a second corset each comprising a “non-return” glass separation device, here similar to that of figure 3;

[0098] - Figure 11 is a sectional view similar to Figure 9 which represents the furnace according to the second embodiment in a first electric melting mode of operation and which further illustrates the first electric melting zone and the second electric melting zone respectively covered with a layer of vitrifiable mixture retained by blocking means and the melting of which to obtain the molten glass is carried out solely in said zone with electricity for energy, without resorting to the flame melting zone;

[0099] - Figure 12 is a sectional view similar to Figure 9 which represents the furnace according to the second embodiment in a second hybrid operating mode in which the melting of the vitrifiable mixture is carried out jointly in the first and second electric melting zones and in the flame melting zone and which illustrates the two electric melting zones covered with a layer of vitrifiable mixture respectively introduced by a first charging unit and by a second charging unit of a first charging device, and the flame melting zone into which vitrifiable mixture is introduced by a second charging device which is separate from said first charging device. DETAILED DESCRIPTION OF THE FIGURES

[0100] In the remainder of the description, the longitudinal, vertical and transverse orientations will be adopted without limitation with reference to the trihedron (L, V, T) shown in the figures.

[0101] The terms "upstream" and "downstream" will also be used by convention in reference to the longitudinal orientation, as well as "upper" and "lower" or "top" and "bottom" in reference to the vertical orientation, and finally "left" and "right" in reference to the transverse orientation.

[0102] In the present description, the terms "upstream" and "downstream" correspond to the main flow direction of the glass in the furnace, the glass flowing from upstream to downstream along a longitudinal axis A-A' of the hybrid furnace (upstream at A, downstream at A') as shown in particular in Figures 2 and 9.

[0103] Furthermore, the terms "belt" and "loop" are synonymous here, these terms relating to the recirculation of the glass in the furnace being well known to those skilled in the art, as are respectively the notions of "cold vault" and "hot vault" for a furnace intended for the manufacture of glass.

[0104] The figures illustrating the hybrid oven according to the invention are not to scale.

[0105] Figures 1 and 2 show sectional views illustrating, respectively from the side and from above, a hybrid furnace 10 for the manufacture of glass according to a first embodiment of the invention.

[0106] By analogy with the third furnace design described previously, the term "hybrid" is used here to describe the furnace according to the invention, in particular because of the possible use of two different energy sources, in particular when the operating mode of the furnace is the so-called hybrid mode in which the melting of the vitrifiable mixture is obtained by jointly using electrical energy and combustible energy.

[0107] However, the analogy with the present invention does not go further since the electrical energy (constituting a first source of energy) and the combustible energy (constituting a second source of energy) are capable of being exclusively used one or the other to obtain the melting, in particular in the other operating modes of the furnace, so that - in the event of use - the electrical energy never constitutes a supplement in a hybrid furnace 10 according to the invention.

[0108] The hybrid furnace 10 according to the invention is particularly intended to supply a glass float unit on a bath of molten metal, generally tin, for the manufacture of flat glass.

[0109] As illustrated by figures 1 and 2, the hybrid furnace 10 according to the first embodiment comprises successively from upstream to downstream, along said longitudinal axis A-A' of the furnace, a melting zone 100, a refining and homogenization zone 200 (hereinafter referred to as refining zone 200) and a glass cooling zone 300.

[0110] Preferably, the hybrid oven 10 has a design symmetry with respect to said longitudinal axis A-A'.

[0111] In a hybrid furnace 10 according to the invention, said melting zone 100 comprises at least one melting zone 110 using a first energy, for example electrical energy, and a melting zone 120 using a second energy, for example combustible energy, in other words a second energy different from said first energy.

[0112] In the remainder of the description and in a non-limiting manner, said at least one fusion zone 110 corresponds to a so-called “electric” fusion zone while said fusion zone 120 corresponds to a so-called “flame” fusion zone due to the use of at least one fuel.

[0113] In a hybrid furnace 10 according to the invention, said at least one electric melting zone 110 and the flame melting zone 120 together forming said melting zone 100 of the furnace are structurally distinct, that is to say constitute separate melting zones, and are functionally independent of each other.

[0114] Said at least one electric melting zone 110 is capable of delivering a maximum draft which is less than or equal to the nominal draft of the furnace, i.e. between 0% and 100% of the nominal draft, preferably up to 100% in order to be able to obtain said nominal draft solely by electric melting. The flame melting zone 120 is capable of delivering a maximum draft which is less than or equal to the nominal draft of the furnace, i.e. between 0 and 100% of the nominal draft, preferably up to 100% in order to be able to obtain said nominal draft solely by flame melting, or even is between 0 and 50% of the nominal draft.

[0115] When the flame fusion zone 120 is capable of delivering a maximum draw which is between 0 and 50% of the nominal draw, said nominal draw is only capable of being obtained by jointly using flame fusion and electric fusion or only said at least one electric fusion zone 110 if said at least one electric fusion zone 110 is capable of delivering a maximum draw corresponding to 100% of the nominal draw.

[0116] Preferably and in comparison to said at least one electric melting zone 110, the hybrid furnace 10 according to the invention comprises a single flame melting zone 120.

[0117] According to the invention, said at least one electric melting zone 110 and said flame melting zone 120 are configured to be able to operate independently of one another so as to allow selective use of one and / or the other of said melting zones 110 and 120 and thereby provide energy flexibility to said hybrid furnace 10.

[0118] Thanks to this design, the hybrid furnace 10 is capable of operating according to several operating modes which are notably determined according to the use made of a single energy or two energies simultaneously, that is to say electricity and / or a fuel, for the melting of the vitrifiable mixture.

[0119] Said operating modes of the hybrid oven 10 will be described in more detail later with reference to FIGS. 5 to 7.

[0120] The hybrid oven 10 according to the invention is in fact capable of operating in an operating mode which can be selectively chosen from:

[0121] - a first electric melting operating mode in which the molten glass is produced solely by said at least one electric melting zone 110; - a second hybrid operating mode in which the molten glass is produced jointly by said at least one electric melting zone 110 and by said flame melting zone 120;

[0122] - a third flame fusion operating mode in which the molten glass is produced solely by said at least one flame fusion zone 120.

[0123] Advantageously, the hybrid furnace 10 is further characterized by this multimode type operation, allowing, depending on the selected operating mode, to choose in particular the energy(s) which will be used to melt the vitrifiable mixture, giving the hybrid furnace 10 according to the invention energy flexibility.

[0124] The melting zone 100 will first be described, followed by the refining zone 200 and the glass cooling zone 300 of a hybrid furnace 10 according to the first embodiment.

[0125] The hybrid furnace 10 comprises, on the one hand, at least one electric melting zone 110 which is capable of being supplied with vitrifiable mixture by at least one first charging device 610 and, on the other hand, the flame melting zone 120 which is capable of being supplied with vitrifiable mixture by at least one second charging device 620.

[0126] The second charging device 620 associated with the flame melting zone 120 is separate and independent in operation from the first charging device 610 associated with said at least one electric melting zone 110 so that it is possible to selectively use one and / or the other, depending on the operating mode of the furnace chosen.

[0127] In the first embodiment of the invention which is shown in Figures 1 to 7, the hybrid furnace 10 comprises a single electric melting zone 110, called cold vault, and said flame melting zone 120, called hot vault.

[0128] Preferably, the hybrid furnace 10 comprises a first charging device 610 consisting of a single charging unit for supplying vitrifiable mixture to the electric melting zone 110, said first charging device 610 being represented schematically by an arrow in FIG. 2. Preferably, the charging unit forming said first charging device 610 is arranged longitudinally, upstream of the electric melting zone 110 as illustrated in FIG. 2.

[0129] Alternatively, said first charging device 610 comprises more than one charging unit, for example two charging units, to supply said electric melting zone 110 which is of the cold vault type.

[0130] Alternatively, the first charging device 610 is not arranged longitudinally but transversely relative to the axis (A-A') of the oven, in particular when the first charging device 610 comprises more than one charging unit.

[0131] Advantageously, the first charging device 610 is configured to spread the vitrifiable mixture in a layer covering the entire surface of the molten glass in the electrical melting zone 110, preferably in a substantially uniform manner.

[0132] As an example, reference may be made to the teachings of document FR2599734 which describes a charging device or charging machine capable of spreading the vitrifiable mixture in such a layer covering the surface of a bath of molten glass.

[0133] Preferably, the second charging device 620 for supplying vitrifiable mixture to said flame melting zone 120 comprises a first charging device 622 and a second charging device 624 which are arranged transversely on either side of said flame melting zone 120, preferably orthogonally to the longitudinal axis (A-A') of the furnace.

[0134] Alternatively, the second charging device 620 comprises only one charging device for supplying said flame melting zone 120 with vitrifiable mixture.

[0135] The first charging unit 622 and the second charging unit 624 have each been schematically represented by an arrow in Figure 2.

[0136] Many examples of embodiments of a furnace are known from the state of the art, in particular but not exclusively with an endless screw, which are capable of supplying vitrifiable mixture to such a flame melting zone 120 of a hybrid furnace 10 according to the invention. The vitrifiable mixture (also sometimes called “composition”) is generally made up of raw materials and cullet (or “cullet”), the melting of which makes it possible to obtain molten glass.

[0137] Cullet is commonly known as glass scraps obtained from glass recycling, which are crushed and usually cleaned before being added to raw materials to make new glass.

[0138] Advantageously, cullet promotes fusion, that is, the transformation by melting of the vitrifiable mixture into glass. The use of cullet also saves sand and therefore uses less energy because cullet has a lower melting point than sand, which helps reduce the carbon footprint of the production process.

[0139] In addition, cullet allows used glass to be recycled (glass being infinitely recyclable), the quantities of raw materials needed to manufacture glass being reduced proportionally, which again contributes to reducing the carbon footprint of the production process.

[0140] Advantageously, the vitrifiable mixture contains 10 to 40% cullet, preferably 30 to 70%, or even 100% cullet.

[0141] Preferably, the vitrifiable mixture introduced into the furnace by the first charging device 610 associated with said at least one electric melting zone 110 and the vitrifiable mixture introduced into the furnace by the second charging device 620 associated with said flame melting zone 120 have a similar composition. This is also the case when the electric melting zone 110 and the flame melting zone 120 are used jointly in the second so-called hybrid operating mode.

[0142] By “similar” composition of vitrifiable mixture, we mean a substantially identical chemical composition which corresponds to that of the glass to be manufactured.

[0143] However, the vitrifiable mixture respectively introduced into the electric melting zone 110 and the flame melting zone 120 is not necessarily identical, in particular it is possible to have a variation in the quantity of cullet in each of the vitrifiable mixtures, or even a selective addition of refining agent(s) in one and not in the other.

[0144] Advantageously, said at least one electric melting zone 110 and said flame melting zone 120 are arranged in series so that the molten glass produced by one of said melting zones located upstream is capable of flowing into the other of said melting zones located downstream.

[0145] By such an arrangement, molten glass produced by one of said melting zones mixes with molten glass produced by the other of said melting zones when said electric and flame melting zones are used together, as in the second hybrid mode of operation of the furnace.

[0146] In this first embodiment, the hybrid furnace 10 comprises, for example, a longitudinal charging zone 111 in which the first charging device 610 (also called a charging unit) is arranged, which is intended to introduce the vitrifiable mixture into the electric melting zone 110, said charging device 610 being represented schematically by an arrow in FIGS. 1 and 2.

[0147] Advantageously, the charging device 610 is configured to deposit the vitrifiable mixture so as to form a layer 112 over the entire surface of a glass bath 113 as illustrated in particular by FIGS. 5 and 6 in which the layer 112 of vitrifiable mixture has been materialized.

[0148] The layer 1 12 of vitrifiable mixture forms an insulating layer between the glass bath 1 13 and a vault 1 14 of the electric melting zone 1 10, which is why such an electric melting zone 1 10 is called a “cold vault”.

[0149] Preferably, the glass bath 113 is uniformly covered with such a layer 112 consisting of vitrifiable mixture, for example 10 to 40 cm thick, and below which the complex chemical reactions take place which, described in the preamble to the present application, lead to the production of molten glass.

[0150] The electrical melting zone 110 comprises electrodes 115 configured to melt the vitrifiable mixture introduced by the first charging device 610 in order to obtain molten glass, in particular said bath 113 of molten glass illustrated in FIG. 1.

[0151] In the electric melting zone 1 10, the power dissipated around the electrodes 1 15 generates a zone of strong convections comprising in particular very intense ascending currents which provide the necessary calories at the boundary between the melt and the vitrifiable mixture forming said layer 1 12.

[0152] Furthermore, although permeable to carbon dioxide (CO2), the layer 1 12 of vitrifiable mixture present on the surface of the bath 1 13 advantageously makes it possible to trap by condensation or by chemical reactions the vapors, sometimes toxic depending on the composition, emitted by the molten glass.

[0153] Advantageously, the electrodes 1 15 are arranged on the surface so as to immerse in the bath 1 13 of glass, through the layer 1 12 covering the surface of the bath 1 13 as illustrated in FIG. 1.

[0154] Preferably, the dipping electrodes 115 extend vertically. Alternatively, the dipping electrodes 115 extend obliquely, i.e. are inclined so as to present a given angle relative to the vertical orientation.

[0155] Alternatively, the electrodes 115 are arranged across a sole 116 of the electric melting zone 110 so as to be completely immersed in the bath 113, the rising electrodes (as opposed to the plunging electrodes) preferably extending vertically, alternatively obliquely.

[0156] Compared to electrodes arranged across the sole, the immersing electrodes 1 15 also allow easier monitoring of their state of wear and result in dissipation of the electrical energy which is advantageously closer to the melting interface, of the layer 1 12 of vitrifiable mixture.

[0157] In addition, the plunging electrodes 1 15 make it possible, in comparison with rising electrodes, to maintain a base 1 16 of the electrical fusion zone 1 10 which is free of any openings.

[0158] Preferably and as illustrated by FIG. 1, the base 116 of the electrical melting zone 110 is flat. Alternatively, the base 116 comprises at least one variation in depth relative to the surface of the glass bath 113, said variation comprising at least one elevation and / or at least one difference in level.

[0159] Preferably, the melting electrodes 115 are distributed regularly in the bath 113. Furthermore, the number of nine electrodes 115 shown here in FIGS. 1 and 2 is only an illustrative example and therefore in no way limiting.

[0160] Alternatively, the electrical fusion zone 110 could cumulatively comprise plunging electrodes and rising electrodes.

[0161] According to another arrangement variant, at least a portion of the electrodes 115 pass through at least one side wall delimiting said electrical fusion zone 110, said electrodes 115 then extending horizontally and / or obliquely.

[0162] Advantageously, the electrodes 1 15 are made of molybdenum, this refractory metal withstanding temperatures of 1700°C being particularly suitable for enabling such melting of the glass to be achieved using the Joule effect, the glass only becoming conductive at high temperature.

[0163] Advantageously, the electrical fusion zone 1 10 comprises a low convection zone, called the buffer zone 1 17, which is located between the free end of the plunging electrodes 1 15 and the base 1 16.

[0164] The electric melting zone 1 10 of the hybrid furnace 10 is configured to have, below said plunging electrodes 1 15, a depth determined so as to obtain such a buffer zone 1 17 of low convection.

[0165] Preferably, the depth between the free end of the immersing electrodes 1 15 and the base 1 16 is greater than 600 mm, preferably greater than 800 mm.

[0166] Such a low convection buffer zone 117 is another reason for preferring dipping electrodes 115 over rising electrodes passing through the floor 116.

[0167] Advantageously, the presence of a low convection buffer zone 117 directly contributes to obtaining high-quality glass by promoting a longer residence time for the glass in the electric melting zone 110. As illustrated by FIGS. 1 and 2, the electric melting zone 110 is located upstream of the flame melting zone 120, the glass flowing into the hybrid furnace 10 from upstream to downstream, i.e. along the longitudinal axis A-A' of the furnace.

[0168] Advantageously, the electric fusion zone 110 and the flame fusion zone 120 located downstream are connected to each other by a corset 160, that is to say a zone of reduced width, as illustrated in FIG. 2.

[0169] The molten glass produced by said electric melting zone 110 therefore advantageously mixes with the molten glass produced by the flame melting zone 120 when said electric and flame melting zones are used jointly as in the second hybrid operating mode of the furnace.

[0170] When the flame melting zone 120 is not used, as in the first electric melting operating mode, the molten glass produced by the electric melting zone 110 then flows through the flame melting zone 120 to the refining zone 200 located further downstream.

[0171] Advantageously, such a corset 160 makes it possible to ensure cooling of the molten glass when the glass flows from the electric melting zone 110 to the flame melting zone 120, said cooling of the glass being all the more important as the corset 160 has a great length.

[0172] Figure 2 illustrates in a non-limiting manner an exemplary embodiment of the corset 160 connecting the electric fusion zone 110 to the flame fusion zone 120.

[0173] According to this embodiment, the passage from the electric melting zone 110 to the corset 160 is made by a sudden narrowing of the width and the passage section of the glass, for example here by walls forming an angle of 90° with the longitudinal axis A-A' of the furnace, and the passage from the corset 160 to the flame melting zone 120 is made conversely by a sudden widening of the passage section of the glass, for example here also by walls forming an angle of 90° with the longitudinal axis A-A' of the furnace.

[0174] Alternatively, the angle at the entrance of the corset 160 could have a value which is greater than 90° so that the narrowing of the width is less abrupt, more gradual, similarly the value of the angle at the exit of the corset 160 could be chosen so that the widening is also less abrupt, more gradual along the longitudinal axis A-A' of the furnace.

[0175] Advantageously, the molten glass flowing from upstream to downstream through the corset 160 is taken from the lower part of the electrical melting zone 110, i.e. from the bottom, the glass there being by comparison “colder” than in the zone located between the electrodes 115 which has strong convections.

[0176] The corset 160 comprises a sole 165 which is connected to the sole 116 of the electric melting zone 100 of the hybrid furnace 10.

[0177] Advantageously, the hybrid furnace 10 comprises a so-called “anti-return” glass separation device 170 which is configured to prevent the molten glass from returning from the flame melting zone 120 to the electric melting zone 110.

[0178] The separation device 170 is positioned at the level of the corset 160, that is to say between the electric melting zone 100 and the flame melting zone 120 to ensure the anti-return function of the glass.

[0179] Advantageously, the separation device 170 is capable of preventing the glass from returning to the electric melting zone 110, whether the electric melting zone 110 is used or not, which depends on the operating mode of the hybrid furnace 10.

[0180] Several examples of the embodiment of such a device 170 for “non-return” separation of the glass will be described below.

[0181] According to a first exemplary embodiment illustrated by figure 3 which represents in detail the corset 160 of the hybrid furnace 10 according to the first embodiment of figures 1 and 2, the device 170 for “anti-return” separation of the glass is formed by at least one elevation 161 of the sole 165 of said corset 160.

[0182] Preferably, the elevation 161 comprises, successively from upstream to downstream, at least a first ascending section 164, a second summit section 166 and a third descending section 168.

[0183] Advantageously, the elevation 161 extends transversely over the entire width of the corset 160.

[0184] Of course, such an elevation 161 can have numerous geometric variants as to its general shape, its dimensions, in particular according to the configuration of each of the different sections 164, 166 and 168 constituting it.

[0185] Preferably, the ascending section 164 is inclined at an angle (a) determined so as to form a ramp capable of causing the molten glass to rise towards the summit section 166 of the elevation 161 as illustrated in FIG. 3.

[0186] Preferably, the ascending section 164 is an inclined plane, having for example an acute angle (a) of between 20° and 70°, said angle (a) being noted as the angle between the ascending section 164 of the elevation 161 and the horizontal, taking here as reference the flat sole 116 of the electrical fusion zone 110.

[0187] As a variant (not shown), the ascending section 164 is stepped, for example, in a staircase with at least one step, or even two or more steps, the height and / or length dimensions of which may or may not be identical.

[0188] Preferably, the summit section 166 is flat, forming a horizontal plateau.

[0189] Advantageously, the summit section 166 thus extends longitudinally over a given length, preferably here greater than or equal to half the total length of the corset 160.

[0190] The summit section 166 determines a maximum height H 1 that the elevation 161 presents and in doing so determines the section of the passage of the molten glass in the corset 160.

[0191] The section 168 descending from the elevation 161 extends vertically, connected by a right angle to the downstream end of the summit section 166 which, flat, extends horizontally.

[0192] Alternatively and as illustrated by FIG. 4 which will be described below in a second exemplary embodiment of the non-return separation device 170, the descending section 168 is configured to progressively accompany the flow of molten glass from the corset 160 towards the flame melting zone 120.

[0193] Such a section 168 is for example formed by an inclined plane, which may or may not be stepped, in particular made in a staircase like the description given previously for the variant embodiments of the ascending section 164. Advantageously, the hybrid furnace 10 comprises at least one atmospheric separation means 174 which is capable of separating the atmosphere of the electric melting zone 110, called the cold vault, and the atmosphere of the flame melting zone 120, called the hot vault.

[0194] As illustrated in Figure 3, the atmospheric separation means 174 is for example formed by a partition which, arranged at the level of the corset 160, extends vertically from the vault and the lower free end of which is preferably in contact with the surface of the glass, or even immersed in the glass.

[0195] Advantageously, the hybrid furnace 10 comprises blocking means 176 which, also called “skimmers”, are capable of retaining the layer 112 of vitrifiable mixture in the electrical melting zone 110 so that said vitrifiable mixture present on the surface of the glass bath 113 does not penetrate into the corset 160.

[0196] Preferably, the blocking means 176 of the layer 112 are structurally distinct from the separation means 174, said blocking means 176 being able to be adjacent or distant from said separation means 174 as illustrated in FIG. 3.

[0197] Alternatively, the separation means 174 is not only capable of ensuring the function of atmospheric separation between the cold vault and the hot vault but also capable of ensuring the function of the blocking means 176.

[0198] Advantageously, the separation means 174 is then configured to be immersed at its free end in the glass bath 113 in order to retain said layer 112 of vitrifiable mixture in the electrical melting zone 110. Preferably, said separation means 174 is positioned at the upstream end of the corset 160 so that said layer 112 of vitrifiable mixture present on the surface of the glass bath 113 does not penetrate into the corset 160 located downstream.

[0199] According to a second exemplary embodiment illustrated by figure 4 and described below by comparison with the first example of figure 3, the glass anti-return separation device 170 similarly comprises at least one elevation 161 of the base 165 of the corset 160 and a dam 172.

[0200] Advantageously, the elevation 161 of the sole 165 of the corset 160 is of a shape substantially identical to that described previously with reference to FIG. 3, namely consisting successively of an ascending section 164, a summit section 166 forming a plateau and a descending section 168.

[0201] Figure 4, however, illustrates the previously described embodiment variant according to which the descending section 168 of the elevation 161 is configured to progressively accompany the flow of molten glass from the corset 160 towards the flame melting zone 120. According to this variant, the section 168 is for example formed by an inclined plane, which may or may not be stepped.

[0202] Advantageously, the dam 172 is arranged above the summit section 166 of the elevation 161 of the base 165.

[0203] In Figure 4, the elevation 161 of the sole 165 has a height H2, noted as previously relative to the horizontal at the level of the flat sole 116 of the electrical fusion zone 110 taken as reference, said height H2 being comparatively lower than the height H1 noted in Figure 3.

[0204] Thus, the depth P2 of glass between the surface S of molten glass and the top section 166 of the elevation 161 of the base 165 is greater than the depth P1 in the embodiment illustrated by figure 3.

[0205] Preferably, the dam 172 associated with the elevation 161 is mounted vertically movable to allow the depth of immersion in the glass bath 113 to be adjusted so as to be able to vary the section of the passage of the glass between the free end of the dam 172 and the top part 166 of the elevation 161.

[0206] Alternatively, the dam 172 is fixed so that the section of the passage of the glass is then constant, that is to say determined by the depth of immersion of said dam 172 in the bath 113 of glass.

[0207] Preferably, the dam 172 is removable, that is to say dismountable, so that said dam 172 is capable of being changed, or even repaired, in particular due to wear occurring in contact with the glass, and this makes maintenance of the hybrid furnace 10 easier.

[0208] The dam 172 is for example made of non-refractory metal or metal alloy, said dam then being capable of being cooled by a cooling circuit (not shown) with heat transfer fluid, in particular a circuit of the “water jacket” type according to the English terms used.

[0209] The dam 172 then participates in the cooling of the glass in the corset 160 by limiting the flow in the corset 160 and thanks to the heat transfer fluid cooling circuit of the “water jacket” type which makes it possible to evacuate part of the heat (calories) transmitted by the glass to the dam.

[0210] Alternatively, the dam 172 is made of refractory material, typically ceramic, for example an electrocast refractory “AZS” (acronym for Alumina-Zircon-Silica) or a refractory metal such as molybdenum.

[0211] According to a third exemplary embodiment (not shown), the separation device 170 comprises only one barrier which, advantageously identical to the barrier 172 which has just been described, is intended to be partly immersed in the bath 113 of molten glass.

[0212] Preferably and by comparison with the arrangement according to the second example illustrated by FIG. 4, the dam is then positioned at the upstream end of the corset 160, at the junction with said electrical fusion zone 110.

[0213] Preferably, the dam extends transversely across the entire width of the corset 160 connecting the electric fusion zone 110 to the flame fusion zone 120.

[0214] Advantageously and as described above, the dam is mounted vertically movable to allow its immersion depth in the glass bath 1 13 to be adjusted or, alternatively, occupies a fixed position determining a given section of passage of the glass.

[0215] Advantageously, the barrier arranged upstream of the corset 160 is capable of ensuring blocking of the layer 112 of vitrifiable mixture covering the bath 113 of glass in the electrical melting zone 110, thus ensuring the function of the blocking means 176 described previously with reference to FIG. 3 for the benefit of the elimination of such blocking means 176.

[0216] As previously described in Figure 4, the dam is advantageously removable, or even depending in particular on the type of material used for its construction is cooled by a heat transfer fluid cooling circuit. Advantageously and according to the embodiments which have just been described, the glass anti-return separation device 170 comprises a dam 172 capable of being partly immersed in the molten glass and / or at least one elevation 161 of the base 165 of the corset 160.

[0217] Advantageously, the hybrid furnace 10 comprises means 500 for cooling the glass capable of selectively cooling the glass in the corset 160.

[0218] In addition to cooling the glass as it flows through the corset 160 connecting the electric melting zone 110 to the flame melting zone 120 located downstream, such cooling means 500 make it possible to further increase the cooling of the glass and, above all, to vary this cooling, whereby regulation of the temperature of the glass is obtained.

[0219] Preferably, the means 500 for cooling the glass in the corset 160 comprise at least one device 510 for cooling by air circulation.

[0220] An example embodiment of a cooling device 510 will be described below, as more particularly shown schematically in Figures 3 and 4.

[0221] Such a device 510 for air cooling the glass comprises, for example, at least intake means 512 for introducing cooling air into the atmosphere of said corset 160 of the hybrid furnace 10.

[0222] Preferably, the glass cooling device 510 comprises evacuation means 514 arranged in the corset 160 to evacuate the hot air and ensure its renewal with fresh cooling air.

[0223] Alternatively, the evacuation means are formed by extraction means (not shown) which, located downstream of the corset 160, are intended to extract the fumes. Advantageously, the hot air is then evacuated with the fumes by said extraction means without the hybrid oven 10 having to be equipped with additional means.

[0224] The air intake means 512 and the air exhaust means 514 of the glass cooling device 510 are for example formed by one or more openings opening into the jambs supporting the vault of the corset 160.

[0225] The air intake means 512 and the air exhaust means 514 are for example arranged transversely on either side of the corset 160, or alternatively on only one of the sides of the corset 160.

[0226] The air intake means 512 and the air exhaust means 514 of the glass cooling device 510 are likely to be arranged upstream of the atmospheric separation means 174 as illustrated in FIG. 3, or even downstream as illustrated in FIG. 4.

[0227] Advantageously, the temperature of the cooling air introduced into the corset 160 is lower than the temperature of the hot air inside the corset 160, the circulating cooling air forming a heat transfer fluid.

[0228] Preferably, the cooling air used is atmospheric air taken from outside the hybrid furnace 10, or even from outside the enclosure of the building in which said hybrid furnace 10 is located.

[0229] Advantageously, the temperature of the atmospheric air used is controlled in order to be regulated; the air can, for example, be pre-cooled or reheated before its introduction to control the temperature, or even the humidity.

[0230] Cooling of the glass is mainly achieved by convection, the introduced cooling air heating up in particular when it comes into contact with the surface of the glass before being evacuated with the heat (calories) transmitted by the glass.

[0231] Advantageously, the circulation of the air is capable of being controlled by means of air blowing means (not shown) such as fans which, associated with said intake and / or exhaust means, are capable of being selectively controlled to vary the flow rate of circulating air.

[0232] According to another exemplary embodiment, the glass cooling means 500 are immersed in the glass flowing from upstream to downstream through said corset 160 in order to allow cooling thereof.

[0233] Such cooling means are for example formed by vertical pads immersed in the glass which are cooled by a heat transfer fluid cooling circuit in order to evacuate the heat transmitted to said pads by the molten glass.

[0234] According to yet another exemplary embodiment, the cooling means 500 comprise a cooling device of the heat exchanger type further comprising metallic cooling means which are arranged in the atmosphere of the corset 160, that is to say above the surface of the glass, and which are crossed by a heat transfer fluid, typically water, in order to cool the air and thereby the molten glass.

[0235] Of course, the cooling means 500 associated with the corset 160 such as those according to the different examples which have just been described are likely to be implemented alone or in combination.

[0236] Advantageously, the glass cooling means 500 associated with the corset 160 make it possible to selectively control the temperature of the glass, which temperature is likely to vary, in particular when the draft varies, an increase in the draft in fact causing an increase in the temperature of the glass.

[0237] Preferably, the glass cooling means 500 associated with the corset 160 are used when the electric melting zone 110 is also used, therefore in the first electric melting operating mode or the second hybrid operating mode of the furnace.

[0238] As described previously, said electric melting zone 100 is connected by the corset 160 to the flame melting zone 120 of the hybrid furnace 10.

[0239] The flame melting zone 120 comprises at least so-called "aerial" burners 125 for melting the vitrifiable mixture capable of being introduced by the second charging device 620, said aerial burners 125 being arranged above the surface S of the molten glass.

[0240] In a variant not shown, the hybrid furnace 10 comprises modulation means (not shown) such as electrical boosting and / or bubbling devices which are arranged in said flame fusion zone 120. The flame fusion zone 120 comprises, for example, four overhead burners which are shown schematically in FIGS. 1 and 2.

[0241] The overhead burners 125 are arranged transversely, and are therefore often called "transverse burners", and are, for example, arranged on either side of the flame fusion zone 120, here shown facing each other, or alternatively preferably offset from each other so as not to face each other.

[0242] The hybrid furnace 10 comprises at least one other burner 215 arranged downstream of the overhead burners 125 and whose main function is not the melting of the vitrifiable mixture but the conduction of the glass.

[0243] Preferably, the hybrid furnace 10 comprises four overhead burners 215 which are distributed transversely on either side of the refining zone 200 like the burners 125.

[0244] The melting of the vitrifiable mixture in the flame melting zone 120 as well as the selective heating of the glass in the refining zone 200 are obtained by the flames delivered respectively by the overhead burners 125 and the burners 215 supplied for this purpose with fuel, which flames develop by combustion above the surface S of the glass.

[0245] This is why the 125 or 215 burners are called "aerial" and this is in particular in contrast to the so-called "submerged" burners corresponding to a completely different technology.

[0246] The delimitation between the flame melting zone 120 and the refining zone 200 as noted in the figures is indicative and in no way limiting. Indeed, the delimitation is not a fixed line but varies depending in particular on the draw and the operating mode of the furnace, said delimitation corresponding by convention to the separation line between the presence and absence of vitrifiable mixture on the surface of the glass bath.

[0247] Advantageously, the flame melting zone 120 extends, along the longitudinal axis (A-A') of the furnace, over a length (L) which further determines the maximum draw likely to be produced by said flame melting zone 120. After the melting zone 100, the refining zone 200 and the cooling zone 300 of the hybrid furnace 10 will now be described according to the first embodiment illustrated by FIGS. 1 and 2.

[0248] The refining zone 200 of the hybrid furnace 10 is configured to eliminate the bubbles (or gas defects) present in the molten glass coming from the electric melting zone 100 and / or the flame melting zone 120 in order to obtain a glass which is of high quality and thus advantageously suitable for supplying a glass float unit.

[0249] To do this, the refining zone 200 is configured to comprise a first convection belt 210, called the upstream recirculation loop, and a second convection belt 220, called the downstream recirculation loop.

[0250] Preferably, the first convection belt 210, called the upstream recirculation loop, is longitudinally shorter than the second convection belt 220 as illustrated in FIG. 1.

[0251] Advantageously, the convection currents in the glass corresponding to said belts 210, 220 operate a mixing promoting the elimination of bubbles and increasing the residence time of the glass in the refining zone 200 which contributes to obtaining a high quality glass.

[0252] Advantageously, the flame melting zone 120 of the hybrid furnace 10 is traversed by said first convection belt 210 of the refining zone 200.

[0253] In the second hybrid operating mode, the first convection belt 210 therefore also participates in the mixing of the molten glass respectively delivered by the electric melting zone 110 and by the flame melting zone 120 which are used jointly.

[0254] The first convection belt 210 and the second convection belt 220 are separated by a zone 230 of inversion of the belts 210, 220 which is determined by a hot point (also called “source point”) corresponding to the hottest point of the glass in the refining zone 200, generally at a temperature above 1500°C.

[0255] Advantageously, the burners 215 are arranged under a vault 240 of the refining zone 200 to obtain said hot point determining the zone 230 of inversion of said belts 210, 220. In the refining zone 200 of the furnace, part of the thermal energy released by the combustion is transmitted directly to the glass by radiation and convection, another part is transmitted by the vault 240 which restores it to the glass by radiation, and which in particular for this reason is called “hot vault”.

[0256] Advantageously, the hybrid furnace 10 comprises a wall 260 in the belt inversion zone 230. Preferably, the wall 260 extends vertically from a hearth 250 of the refining zone 200.

[0257] As illustrated in Figure 1, the wall 260 comprises a top portion which, immersed below the surface S of the glass, determines the passage of the glass from the first convection belt 210, called the upstream recirculation loop, to the second convection belt 220, called the downstream recirculation loop.

[0258] Preferably, the hybrid furnace 10 comprises modulation means (not shown) such as electrical boosting and / or bubblers which, arranged in the flame melting zone 120 and / or the refining zone 200, are capable of allowing the convection of said belts 210, 220 to be modulated in order to facilitate the conduct of the glass manufacturing.

[0259] Advantageously, the modulation means therefore comprise, according to the English term, electrical "boosting", that is to say, additional electrical heating means comprising electrodes and / or bubblers, that is to say a system for injecting at least one gas, such as air or nitrogen, at the level of the floor, the bubbles of which then create an upward movement of the glass.

[0260] Preferably, the hybrid furnace 10 comprises at least one variation 270 of the depth, relative to the surface S of the glass, of the sole 250 of the refining zone 200.

[0261] The depth variation 270 is located in the portion comprising the first convection belt 210 and / or in the portion comprising the second convection belt 220.

[0262] Advantageously, the variation 270 of the glass depth is for example constituted by at least one elevation of the base 250 illustrated by figure 1. As a variant, the variation 270 of the depth is constituted by at least one difference in level of the base 250. The elevation of the base 250 forming the variation 270 of depth, i.e. here a reduction in the depth, is for example constituted by at least one step 272, or even two steps.

[0263] The variation 270 in depth can be carried out more or less gradually, for example by a straight portion 274 in the case of that located upstream of the wall 260 or as a variant by an inclined portion 276 in the case of a step 322 located downstream of the wall 260, at the junction of the refining zone 200 and the glass cooling zone 300.

[0264] Preferably, the cooling zone 300 also comprises a variation 370 in depth which is formed by an elevation comprising, for example, the step 322 to which the inclined portion 276 leads from the floor 250 and another step 332, downstream of said step 322. The step 322 also connects progressively to the other step 332 by an inclined portion 376.

[0265] Alternatively, the straight and inclined portions respectively which have just been described with reference to FIG. 1 could be reversed between the steps 272 on the one hand and the steps 322, 332 on the other hand, or even be of only one and the same type, that is to say either straight or inclined.

[0266] As illustrated by Figure 1 and as has just been described with the successive steps 322 and 332, the cooling zone 300 comprises a base 350 which is configured so that the depth relative to the glass surface S decreases progressively from upstream to downstream, from the wall 260.

[0267] The glass cooling zone 300 of the hybrid furnace 10 is traversed by the second convection belt 220, called the downstream recirculation loop.

[0268] The cooling zone 300 is formed by a conditioning basin 310 which communicates with at least one flow channel 400 which is for example intended to supply high-quality glass to a forming zone located downstream and preferably constituted by a unit for floating the glass on a bath of molten metal (not shown). Advantageously, the conditioning basin 310 of the cooling zone 300 comprises, from upstream to downstream, another corset 320, called the second corset, then an ember 330.

[0269] Advantageously, the atmosphere of the refining zone 200 and the colder atmosphere of the cooling zone 300 are separated from each other by a heat shield 360 extending vertically from a vault 340 to the vicinity of the surface S of the glass, preferably without soaking into the glass.

[0270] Advantageously, in any vertical plane transverse to the longitudinal axis A-A' of the hybrid furnace 10, there are points in the glass in the conditioning basin 310 having a longitudinal velocity component going from downstream to upstream.

[0271] After the conditioning basin 310, no return flow takes place in a flow channel 400 intended to supply glass to the forming zone, in other words the flow of glass in the channel 400 is a “piston” type flow.

[0272] Advantageously, the hybrid furnace 10 according to the invention is capable of delivering a high-quality glass having less than 0.1 bubble per liter, preferably less than 0.05 bubbles per liter, such high-quality glass being particularly suitable for supplying a float unit intended to manufacture flat glass.

[0273] Advantageously, the hybrid furnace 10 is capable of supplying a glass float unit on a bath of molten metal with a nominal output greater than or equal to 400 tonnes per day, preferably between 600 and 900 tonnes per day, or even 1000 tonnes per day or more, and this with high quality glass having less than 0.1 bubble per litre.

[0274] Preferably, the hybrid glass manufacturing furnace 10 according to the invention feeds, via said flow channel 400, a unit for floating the glass on a bath of molten metal, for example tin, intended for the manufacture of flat glass.

[0275] According to the invention and as described previously, the hybrid furnace 10 according to the first embodiment is further characterized by the fact of comprising an electric melting zone 110 and a flame melting zone 120 which, being capable of operating independently of one another, give said hybrid furnace 10 energy flexibility. In a hybrid furnace 10 according to the invention, the energy flexibility relates to the energy used for the step of melting the vitrifiable mixture which is the most energy-intensive of the glass-making process.

[0276] Advantageously, the electrodes 115 constitute the heating means of the electric melting zone 110 making it possible to obtain the melting of the vitrifiable mixture while the burners 125 preferably constitute the only heating means of the flame melting zone 120. Alternatively, said burners 125 constitute the main heating means in the case of use of additional electric heating means (called "boosting") comprising immersed electrodes.

[0277] Thanks to this design of the melting zone 100 of the hybrid furnace 10, it is in fact possible to choose one of the three aforementioned operating modes, namely the first electric melting operating mode, the second so-called hybrid operating mode and the third flame melting operating mode.

[0278] Advantageously, the electric melting zone 110 is capable of delivering a maximum draw which is less than or equal to the nominal draw of the furnace, i.e. between 0% and 100% of the nominal draw.

[0279] Preferably, the electrical fusion zone 110 is capable of delivering a maximum draw of up to 100% in order to be able to obtain said nominal draw solely by electrical fusion, typically in the first operating mode.

[0280] Advantageously, the flame melting zone 120 is capable of delivering a maximum draw which is less than or equal to the nominal draw of the furnace, i.e. between 0 and 100% of the nominal draw, preferably up to 100% in order to be able to obtain said nominal draw solely by flame melting, typically in the third operating mode.

[0281] Preferably, the flame melting zone 120 is capable of delivering a maximum draft which is between 0 and 50% of the nominal draft. Consequently, obtaining the nominal draft then requires joint use of the electric melting zone 110 with the flame melting zone 120 to reach 100%, such will be the case in the second hybrid operating mode. In a hybrid furnace 10 according to the invention, the energy used for melting the vitrifiable mixture will therefore depend on the selected operating mode, which mode can in particular be determined as a function of the desired draft relative to the nominal draft of the hybrid furnace 10.

[0282] Preferably, the melting of the vitrifiable mixture is carried out in whole or in part in the electric melting zone 110 of the hybrid furnace 10 so that the melting is thus obtained either solely with electrical energy according to the first electric melting operating mode, or mainly with electrical energy in combination with a fuel according to the second hybrid operating mode.

[0283] Advantageously, electricity represents more than 60%, or even 80% or more, of the total energy used in the hybrid furnace 10 for the glassmaking process and particularly for the melting of the vitrifiable mixture, the most energy-intensive stage of the process.

[0284] Indeed, as explained in the preamble, we are still seeking to reduce the carbon footprint of the glass production process.

[0285] Thus, when the combustible energy is a fossil energy such as natural gas and, by comparison, the electrical energy is wholly or partly "green" electricity obtained from renewable and decarbonized energies, then electricity will generally be favored at least for this reason.

[0286] However, and although electricity may be preferred as the energy for melting, the hybrid furnace 10 nevertheless also offers a third mode of operation with flame melting using a fuel, which offers the guarantee of always being able to manufacture glass, including for example in the event of a problem with the electricity supply, avoiding any forced shutdown of the hybrid furnace 10.

[0287] In a known manner, the hybrid furnace 10 may comprise regenerators made of refractory materials operating (for example in pairs and in inversion) or even metal exchangers which respectively use the heat contained in the fumes resulting from manufacturing to preheat the fluids (fuel and oxidant) supplying the burners 125 and / or 215 and thus improve combustion.

[0288] The 125 overhead burners (and the 215 burners) produce a flame by combustion which can be obtained by combining different types of fuel and oxidant but the choice of which also has direct consequences in the carbon footprint of glass manufacturing, namely the direct and indirect greenhouse gas emissions which are linked to the manufacturing of the product, in particular carbon dioxide (CO2) emissions.

[0289] However, if the fuel most often used in 125 burners is gas, it is possible to further improve the carbon footprint of the glass manufacturing process by using a biofuel (in English "green-fuels") in particular a "biogas", preferably "bio-methane" (CH4).

[0290] The term "biogas" means a gas composed essentially of methane and carbon dioxide which is produced by methanization, that is, the fermentation of organic matter in the absence of oxygen.

[0291] Hydrogen (H2) will be used even more preferably as fuel because, compared to biogas, it advantageously does not contain carbon, and without carbon there are no carbon dioxide (CO2) emissions.

[0292] For the combustion carried out in burners 125 and also 215, the oxygen present in the air is generally used as the oxidant, which air can however be enriched with oxygen in order to obtain superoxygenated air, or even almost pure oxygen is used in the particular case of oxycombustion.

[0293] As indicated previously, preheating of the fluids (fuel and oxidant) supplying the burners 125, 215 is likely to be carried out to improve combustion, in particular using metal exchangers using the heat contained in the fumes resulting from manufacturing.

[0294] Advantageously, the energy flexibility obtained with a hybrid furnace 10 according to the invention is therefore total, further allowing the choice of both the energy(s) used for melting and the proportion in which they are used. Advantageously, the selection of one of the three operating modes of the hybrid furnace 10 is for example a function of at least one selection parameter comprising:

[0295] - an economic criterion which is a function of the respective cost of the electrical energy and the fuel also intended for the melting of the vitrifiable mixture;

[0296] - an ecological criterion which is a function of the carbon footprint (CO2) respectively associated with the electrical energy and the said fuel, and

[0297] - at least one technical criterion which is a function of the draw to be produced in relation to the quantity of molten glass capable of being obtained respectively by means of said at least one electric melting zone 110 and / or the flame melting zone 120 and / or a function of the composition of the glass to be manufactured, or even of the cullet content in the vitrifiable mixture.

[0298] Advantageously, the hybrid oven 10 is capable of being controlled by an associated control unit (UC), in particular capable of being controlled by the control unit (UC) to select, according to at least one of the aforementioned selection parameters, one of the operating modes respectively illustrated by figures 5 to 7 which will be described below.

[0299] Figure 5 illustrates the hybrid furnace 10 according to the first embodiment in the first electric fusion operating mode.

[0300] In this electrical melting embodiment, the glass is produced only in the electrical melting zone 110 by means of the electrodes 115, said zone 110 being supplied for this purpose with vitrifiable mixture by the first charging device 610.

[0301] The second charging device 620 associated with the flame fusion zone 120 is stopped, which is why the arrow illustrating it schematically has been shown in dotted lines.

[0302] As can be seen in Figure 5, the vitrifiable mixture is advantageously distributed uniformly over the surface of the glass bath 113 in a layer 112 which is retained by the blocking means 176 described previously so as not to penetrate into the corset 160.

[0303] In this first electric melting operating mode, in the absence of flame melting by means of overhead burners 125, the second charging device 620 is stopped, no vitrifiable mixture is thus delivered into said flame melting zone 120.

[0304] The molten glass produced in the electric melting zone 110 flows longitudinally from upstream to downstream, the separation device 170 arranged at the level of the corset 160 advantageously preventing any return of the glass to the electric melting zone 110.

[0305] Thus, the molten glass flows from the electric melting zone 110 through the corset 160 until it reaches the flame melting zone 120, then the refining zone 200 where the glass is refined by circulating along the first convection belt 210.

[0306] In the first mode of operation with electric melting, if no fuel is used in the burners 125 to obtain the melting of the vitrifiable mixture, a heating of the glass on the surface by flames using at least one of the burners 215 is however carried out selectively in said refining zone 200 to obtain the hot point so as to perfect the refining and homogenization of the glass by eliminating the bubbles (or gaseous defects) present in the molten glass.

[0307] Advantageously, by adjusting the power of a part of said at least one burner 215 located downstream in the vicinity of the wall 260, it is possible to adjust the longitudinal distribution of temperatures and therefore the position of the hot spot which is an important parameter for operating the furnace.

[0308] The glass will then cross said wall 260 at the belt inversion zone 230, passing from the first convection belt 210 to the second convection belt 220, and travel through the cooling zone 300 following said second convection belt 220.

[0309] In the cooling zone 300, the glass circulating along said second convection belt 220 passes through the second corset 320 then the ember 330 before finally exiting the hybrid furnace 10 through the glass flow channel 400.

[0310] Figure 6 illustrates the hybrid furnace 10 according to the first embodiment in the second hybrid operating mode which will be described below in comparison with Figure 5. In this second hybrid operating mode of the furnace, the electric melting zone 110 and the flame melting zone 120 are used simultaneously to obtain the molten glass and consequently two different energy sources, respectively electricity and a fuel.

[0311] However, the proportion of electricity and fuel is advantageously freely configurable, depending on the aforementioned selection criteria in particular and within the limit of the maximum output that each melting zone 1, 10, 120 is capable of producing in relation to the nominal output of the hybrid furnace 10.

[0312] Thus, the electricity used to power the electrodes 115 and the fuel to power the overhead burners 125 can be used in equal parts, either in a 50 / 50 ratio, or any other ratio.

[0313] Preferably, electricity is predominant over fuel, for example with a ratio of 60 / 40, or even an 80 / 20 ratio (i.e. 80% electricity and 20% fuel).

[0314] Alternatively, one could also favor fuel over electricity, in particular for ecological reasons according to their respective carbon footprint (CO2), such would be the case for example of a fuel advantageously formed by hydrogen (H2), or even biogas, while the electricity would not have been produced from renewable and decarbonized energies but from a fossil energy such as coal.

[0315] As illustrated in FIG. 6, vitrifiable mixture is present in the electric melting zone 110 and in the flame melting zone 120, each being respectively supplied by the first charging device 610 and by the second charging device 620 comprising the first charging unit 622 and the second charging unit 624 which are arranged transversely in this first embodiment.

[0316] The molten glass produced by the electric melting zone 110 flows through the corset 160 as described previously for FIG. 5 but this molten glass then mixes in the flame melting zone 120 with the molten glass produced by the latter, the molten glass resulting from this mixture will then circulate along the first convection belt 210 to the refining zone 200. Thanks to the arrangement in series of the electric melting zone 110 and the flame melting zone 120, the molten glass produced by said zone 110 flows into said flame melting zone 120 located downstream to mix therein.

[0317] Advantageously, the corset 160 comprising the separation device 170, or even the cooling means 500 such as the air circulation cooling device 510, also make it possible to control this flow, in particular the temperature of the glass.

[0318] The path of the molten glass from the refining zone 200 to the channel 400 passing through the cooling zone 300 is identical to that which was previously described with reference to figure 5 so that it will be advantageously referred to, without it being necessary to repeat it again here.

[0319] Figure 7 illustrates the hybrid furnace 10 according to the first embodiment in the third flame fusion operating mode which will be described below in comparison with that of Figure 6.

[0320] In this third operating mode, the molten glass is produced only by the flame melting zone 120, the unused electric melting zone 110 is consequently not supplied with vitrifiable mixture by the first charging device 610 which is stopped as illustrated by the dotted arrow.

[0321] This is the reason why in figure 7, no layer 1 12 of vitrifiable mixture is visible in said zone 1 10 of electric fusion compared to figures 5 and 6 described previously.

[0322] The vitrifiable mixture is introduced transversely on either side into said flame melting zone 120 respectively by the first charging unit 622 and by the second charging unit 624 forming said second charging device 620 of the hybrid furnace 10.

[0323] The fusion of said vitrifiable mixture is obtained thanks to the flames produced by the burners 125 during the combustion of the fuel advantageously consisting of hydrogen (H2), or even a biogas such as bio-methane (CH4).

[0324] The molten glass obtained circulates along the first convection belt 210 extending longitudinally between said flame melting zone 120 and the refining zone 200. Advantageously, the molten glass remains in the flame melting zone 120 without penetrating into the corset 160 located upstream, that is to say in the direction of the electric melting zone 110, thanks in particular to the glass anti-return separation device 170.

[0325] According to the exemplary embodiments illustrated by figures 3 and 4 and described previously, the glass anti-return separation device 170 advantageously comprises a barrier 172 capable of being partly immersed in the molten glass and / or at least one elevation 161 of the base 165 of the corset 160.

[0326] The absence of electrical fusion in this third flame operating mode does not necessarily result in a complete shutdown of the electrical fusion zone 1 10.

[0327] Preferably, the electrodes 115 remain supplied with electricity to maintain a temperature above the devitrification temperature in the electrical melting zone 110. However, in the absence of introduction of any vitrifiable material by the first charging device 610, there is no production of molten glass.

[0328] Advantageously, maintaining such a temperature in the electric fusion zone 110 thus corresponds to a standby mode allowing a faster change of operating mode, whether towards the first electric fusion operating mode or the second hybrid operating mode.

[0329] Alternatively, when operation according to said third mode is envisaged for a long duration, it may then be envisaged to proceed with a shutdown of the electric melting zone 110. Preferably, a means such as a barrier 172 is then arranged in the corset 160 to maintain the glass in the flame melting zone 120.

[0330] As previously for figure 6, the path of the molten glass from the refining zone 200 to the channel 400 via the cooling zone 300 is identical to that which was previously described with reference to figure 5 so that it will be advantageous to refer to it.

[0331] A second embodiment of the hybrid furnace 10 according to the invention will be described below, by comparison with the first embodiment, as illustrated by FIGS. 8 to 12. In this second embodiment, the hybrid furnace 10 comprises a melting zone 100 comprising at least a first electric melting zone 110A and a second electric melting zone 110B.

[0332] In this second embodiment, the hybrid furnace 10 preferably comprises two electric melting zones, respectively 1 10A and 1 10B, alternatively the hybrid furnace 10 could comprise more than two electric melting zones.

[0333] Compared with the first embodiment in which the hybrid furnace 10 comprises a single electric melting zone 110, having at least two or more electric melting zones according to this second embodiment also presents various advantages.

[0334] Depending on the draw to be delivered in electric fusion, it is advantageous to choose to use only one of the electric fusion zones 1 10A and 110B.

[0335] Furthermore, it is also possible, for example, to use only one of the fusion zones when a maintenance operation or other intervention must be carried out in the other of the said electrical fusion zones.

[0336] Advantageously, said electrical fusion zones 110A and 110B are intended to be used together.

[0337] Advantageously, the two electrical fusion zones 110A and 110B are of a design similar to the electrical fusion zone 110 described previously for the first embodiment and will therefore not be described in detail.

[0338] Thus, the two electric melting zones 110A and 110B of the hybrid furnace 10 further comprise electrodes 115 which are for example here six in number in each zone as illustrated by figure 9.

[0339] In this second embodiment, said zones 110A and 110B each have a smaller surface area than that of said fusion zone 110 of the first embodiment.

[0340] Preferably, the electrodes 115 are arranged on the surface so as to immerse in the vitrifiable mixture, the plunging electrodes 115 extending vertically. Preferably, said electrical melting zones 110A and 110B are capable of delivering a pull greater than or equal to that of the electrical melting zone 110 of the first embodiment.

[0341] Advantageously, said electric melting zones 110A and 110B are capable of delivering a maximum draw which is less than or equal to the nominal draw of the furnace, i.e. between 0% and 100% of the nominal draw, preferably up to 100% in order to be able to obtain said nominal draw solely by electric melting.

[0342] As illustrated in FIG. 9, the first electric fusion zone 110A and the second electric fusion zone 110B are arranged transversely on either side of the flame fusion zone 120.

[0343] Preferably, the first electric melting zone 110A and the second electric melting zone 110B are arranged orthogonally to the longitudinal axis (A-A') of the furnace.

[0344] Advantageously, the first charging device 610 comprises a first charging unit 612 for supplying vitrifiable mixture to the first electric melting zone 110A and a second charging unit 614 for supplying vitrifiable mixture to the second electric melting zone 110B.

[0345] The first charging unit 612 and the second charging unit 614 are schematically represented by arrows in Figures 9 to 12. The first charging unit 612 and the second charging unit 614 are arranged transversely to supply vitrifiable mixture respectively to the first electric melting zone 110A and the second electric melting zone 110B.

[0346] Advantageously, the first charging device 612 and the second charging device 614 forming the first charging device 610 are configured to spread the vitrifiable mixture in a uniform layer 112 on the surface of the bath 113 of molten glass in each of said first and second electric melting zones 110A and 110B.

[0347] Advantageously, said electric melting zones 110A and 110B and said flame melting zone 120 are arranged in series so that the molten glass produced by each of said melting zones 110A and 110B flows into the flame melting zone 120 located downstream. The first electric melting zone 110A and the second electric melting zone 110B are respectively connected to the flame melting zone 120 by a first corset 160A and by a second corset 160B.

[0348] Advantageously, the first corset 160A and the second corset 160B are identical to the corset 160 according to the first embodiment and will therefore not be described in more detail.

[0349] Advantageously, the hybrid furnace 10 comprises a device 170 for anti-return separation of the glass in each of said corsets 160A and 160B.

[0350] Preferably, each separation device 170 comprises at least one elevation 161 of the sole 165 as described with reference to FIG. 3 of the first embodiment.

[0351] Advantageously, the hybrid furnace 10 also comprises in each of said first corset 160A and second corset 160B a means 174 of atmospheric separation and blocking means 176 capable of retaining the vitrifiable mixture.

[0352] Advantageously, the hybrid oven 10 comprises cooling means 500, preferably an air circulation cooling device 510 which, identical to that described previously for the first embodiment, is not shown schematically in FIGS. 8 to 12.

[0353] Preferably, said second charging device 620 intended to supply said flame melting zone 120 with vitrifiable mixture comprises at least one charging device comprising a worm screw.

[0354] As illustrated in FIG. 9, the second charging device 620 is arranged longitudinally opposite the furnace, i.e. along the longitudinal axis (A-A') of the furnace, upstream of the flame melting zone 120.

[0355] With the exception of the vitrifiable mixture charging device 620, the hybrid furnace 10 according to the second embodiment comprises a flame melting zone 120 which, comprising overhead burners 125, is identical to that described previously for the first embodiment, to the description of which reference will therefore be made. The hybrid furnace 10 comprises a refining zone 200 and a cooling zone 300 which are respectively identical to those of the first embodiment, to the description of which reference will therefore be made advantageously, the same reference signs having been used for this purpose in FIGS. 8 to 12 illustrating the second embodiment.

[0356] In this second embodiment illustrated by figures 8 to 12, the first electric fusion zone 110A and the second electric fusion zone 110B are arranged transversely on either side of the flame fusion zone 120.

[0357] Alternatively, the first electric melting zone 110A and the second electric melting zone 110B are arranged longitudinally upstream of the flame melting zone 120, one next to the other, with a corset 160A, 160B extending parallel to the longitudinal axis (A-A') of the furnace or obliquely, i.e. forming a given acute angle relative to said longitudinal axis (A-A').

[0358] In such an alternative embodiment, the second charging device 620 is arranged transversely, preferably orthogonally relative to the longitudinal axis (A-A'), relative to the flame fusion zone 120.

[0359] Preferably, the second charging device 620 then comprises a first charging device 622 and a second charging device 624 as in the first embodiment illustrated in FIG. 2, that is to say arranged transversely on either side of the flame melting zone 120 to be supplied with vitrifiable mixture, orthogonally to the longitudinal axis (A-A') of the furnace.

[0360] Advantageously, the hybrid oven 10 according to the second embodiment is capable of operating according to several operating modes, whereby energy flexibility is further obtained.

[0361] As for the first embodiment, the hybrid furnace 10 respectively has a first electric fusion operating mode, a second hybrid operating mode and a third flame fusion operating mode.

[0362] Advantageously, the hybrid oven 10 is capable of being controlled by a control unit (CU), shown schematically in FIG. 8, in order in particular to select one of said operating modes according to at least one of the selection parameters described previously, namely an economic criterion, an ecological criterion and at least one technical criterion.

[0363] Figure 11 illustrates the hybrid furnace 10 according to the second embodiment of the invention in the second electric melting mode of operation in which the molten glass is produced solely by electric melting, i.e. with electricity for energy, without using the flame melting zone 120.

[0364] Consequently, the overhead burners 125, like the second charging device 620 associated with the flame fusion zone 120, are stopped, which is illustrated respectively by the absence of flames and the use of the dotted line for the arrow.

[0365] As illustrated in Figure 11, the first electrical melting zone 110A and the second electrical melting zone 110B are covered with a layer 112 of vitrifiable mixture, preferably uniformly, which layer 112 is retained by blocking means 176 which extend longitudinally upstream of the first corset 160A and the second corset 160B.

[0366] The first electric melting zone 1 10A and the second electric melting zone 10B are thus only supplied with vitrifiable mixture, respectively by the first charging unit 612 and by the second charging unit 614.

[0367] The molten glass respectively produced by the first electric melting zone 110A and by the second electric melting zone 110B will flow transversely through the first corset 160A and the second corset 160B to the flame melting zone 120 traversed by the first convection belt 210 of the refining zone 200.

[0368] The molten glass then passes through the refining zone 200 and then the cooling zone 300 to the flow channel 400.

[0369] The first mode of operation with electric melting in a hybrid furnace 10 according to this second embodiment being otherwise identical to that described previously for the first mode with reference to FIG. 5, it will therefore not be described again in more detail. FIG. 12 illustrates the hybrid furnace 10 according to the second embodiment of the invention in the second hybrid mode of operation in which the melting of the vitrifiable mixture is carried out jointly in said first and second electric melting zones 110A and 110B as well as in the flame melting zone 120.

[0370] As illustrated in Figure 12, the two electric melting zones 110A and 110B and the flame melting zone 120 are covered with a layer 112 of vitrifiable mixture.

[0371] The first electric melting zone 110A and the second electric melting zone 110B are each respectively supplied by the first charging unit 612 and by the second charging unit 614 while the flame melting zone 120 is supplied longitudinally by the second charging device 620 arranged upstream of the hybrid furnace 10.

[0372] In this hybrid operating mode, part of the molten glass produced by the first electric melting zone 1 10A and the second electric melting zone 1 10B is therefore obtained with electricity while the other part is obtained with a fuel used in the overhead burners 125 to produce the flames illustrated in Figure 12.

[0373] For this second embodiment and unlike the first mode, the third flame fusion operating mode has not been shown in a figure.

[0374] Compared with the previous figure 12, the flame fusion operating mode is distinguished by the fact that the fusion is obtained by means of the overhead burners 125, here only by said burners 125 in the absence of additional electric heating means ("boosting"), without use of the first zone 110A and the second zone 110B of electric fusion.

[0375] The first embodiment illustrated by Figures 1 to 7 and the second embodiment illustrated by Figures 8 to 12 are given solely as non-limiting examples of the present invention.

[0376] The invention relates to a hybrid furnace 10 for the manufacture of glass, in particular for supplying a float unit, said hybrid furnace 10 with a longitudinal axis (A-A') further comprising: - at least one electrical melting zone 110 comprising electrodes 115 which is capable of being supplied with vitrifiable mixture by a first charging device 610;

[0377] - a flame melting zone 120 comprising at least overhead burners 125 which is capable of being supplied with vitrifiable mixture by a second charging device 620, separate from said at least one first charging device 610, in which said at least one electric melting zone 110 and the flame melting zone 120 arranged in series are configured to be able to operate independently of one another so as to allow selective use of one and / or the other of said melting zones 110, 120 which thus gives the furnace 10 energy flexibility.

[0378] Advantageously, the hybrid furnace 10 according to the invention is capable of supplying a glass float unit (not shown).

[0379] According to another aspect, the invention relates to an assembly for the manufacture of flat glass comprising a hybrid glass manufacturing furnace 10 and a unit for floating the glass on a bath of molten metal which, arranged downstream, is supplied with glass by said furnace 10 via said at least one flow channel 400.

[0380] According to yet another aspect, the invention relates to a method for manufacturing glass which is implemented in a hybrid furnace 10 according to the invention, in particular for supplying a glass float unit on a bath of molten metal.

[0381] Said glass manufacturing method comprises at least one melting step carried out in the hybrid furnace 10 operating according to one of the operating modes of said hybrid furnace described previously, that is to say selectively chosen from:

[0382] - a first electric melting operating mode in which the molten glass is produced solely by said at least one electric melting zone 110;

[0383] - a second hybrid operating mode in which the molten glass is produced jointly by said at least one electric melting zone 110 and by said flame melting zone 120; - a third flame melting operating mode in which the molten glass is produced solely by said at least one flame melting zone 120.

[0384] Advantageously, prior to implementing the melting step in the hybrid furnace, the glass manufacturing method comprises at least one step of determining the operating mode consisting of selecting one of said operating modes of the furnace as a function of at least one selection parameter such as an economic criterion and / or an ecological criterion and / or at least one technical criterion respectively described previously.

[0385] Thus, said determination step consists of selecting one of said operating modes as a function of at least one selection parameter comprising:

[0386] - an economic criterion which is a function of the respective cost of the electrical energy and the fuel also intended for the melting of the vitrifiable mixture;

[0387] - an ecological criterion which is a function of the carbon footprint (CO2) respectively associated with the electrical energy and the said fuel, and

[0388] - at least one technical criterion which is a function of the draw to be produced in relation to the quantity of molten glass capable of being obtained respectively by means of said at least one electric melting zone 110 and / or the flame melting zone 120 and / or a function of the composition of the glass to be manufactured, or even of the cullet content in the vitrifiable mixture.

[0389] Advantageously, said determination step intended to select one of the operating modes of the hybrid oven 10 is carried out by means of the control unit (UC) associated with the hybrid oven 10.

[0390] Advantageously, when the second hybrid operating mode is selected at the end of the determination step, the method comprises an additional determination step then consisting of determining the quantity of molten glass to be produced respectively by said at least one electric melting zone 110 and by the flame melting zone 120 in order to obtain the desired output. Said additional determination step further determines the respective contribution of said at least one electric melting zone 110 and of the flame melting zone 120, for example a ratio of 50 / 50 or a ratio of 80 / 20 when electrical energy is favored over fuel.

[0391] Preferably, said desired draft is equal to the nominal draft of the hybrid furnace 10.

[0392] Advantageously, the control unit (UC) determines the control parameters of the corresponding furnace, in particular those of the electrodes 115 and / or the overhead burners 125 but also those of the first charging device 610 and / or the second charging device 620 in order to adjust the quantity of vitrifiable material to be charged into said at least one electric melting zone 110 and / or into the flame melting zone 120 according to the operating mode of the furnace and to obtain said draw.

Claims

REVENUES 1. Hybrid furnace (10) for the manufacture of glass, in particular for supplying a glass float unit on a bath of molten metal, said hybrid furnace (10) with a longitudinal axis (A-A') comprising: - at least one electrical melting zone (110) which is capable of being supplied with vitrifiable mixture by at least one first charging device (610) and which comprises electrodes (115) for melting said vitrifiable mixture; - a flame melting zone (120) which, distinct from said at least one electric melting zone (110), is capable of being supplied with vitrifiable mixture by at least one second charging device (620) and which comprises at least overhead burners (125) for melting said vitrifiable mixture, said overhead burners (125) being arranged above the surface (S) of the molten glass, in which said at least one electric melting zone (110) and said flame melting zone (120) are arranged in series so that the molten glass produced by one (110) of said melting zones located upstream is capable of flowing into the other (120) of said melting zones located downstream and in which said at least one electric melting zone (110) and said flame melting zone (120) are configured to be able to operate independently of one another. the other so as to allow selective use of one and / or the other of said fusion zones (1 10,120) in order to give the oven energy flexibility, - a zone (200) for refining the molten glass delivered by said at least one electric melting zone (110) and / or said flame melting zone (120), said refining zone (200) being configured to comprise a first convection belt (210) and a second convection belt (220); and - a glass cooling zone (300) comprising a conditioning basin (310) which is traversed by the second convection belt (220) and which is connected to at least one glass flow channel (400).

2. Furnace according to claim 1, characterized in that said at least one electric melting zone (110) is capable of delivering a maximum draw which is less than or equal to the nominal draw of the furnace, i.e. i.e. between 0% and 100% of the nominal draw, preferably up to 100% in order to be able to obtain said nominal draw solely by electrical fusion.

3. Oven according to one of claims 1 or 2, characterized in that the electrodes (1 15) are arranged on the surface so as to immerse in the vitrifiable mixture, said immersing electrodes (1 15) preferably extending vertically.

4. Furnace according to one of claims 1 to 3, characterized in that said flame melting zone (120) is traversed by the first convection belt (210) of the refining zone (200).

5. Furnace according to any one of claims 1 to 4, characterized in that said flame melting zone (120) is capable of delivering a maximum draft which is less than or equal to the nominal draft of the furnace, i.e. between 0 and 100% of the nominal draft, preferably up to 100% in order to be able to obtain said nominal draft solely by flame melting, or even between 0 and 50% in order to be able to obtain said nominal draft by jointly using flame melting and electric melting.

6. Furnace according to claim 5, characterized in that the flame melting zone (120) extends, along the longitudinal axis (A-A') of the furnace, over a length (L) which further determines the maximum draft capable of being produced by said flame melting zone (120).

7. Oven according to any one of claims 1 to 6, characterized in that said at least one electric melting zone (110) is connected by a corset (160, 160A, 160B) to said flame melting zone (120).

8. Furnace according to claim 7, characterized in that the hybrid furnace (10) comprises a so-called anti-return separation device (170) which, arranged at the level of the corset (160, 160A, 160B), is capable of preventing a return of the molten glass from said flame melting zone (120) to said at least one electric melting zone (110).

9. Furnace according to claim 8, characterized in that said separation device (170) comprises a barrier (172) capable of being partially immersed in the molten glass.

10. Oven according to claim 8 or 9, characterized in that said separation device (170) comprises at least one elevation (161) of a sole (165) of the corset (160, 160A, 160B). 1 1. Furnace according to any one of claims 7 to 10, characterized in that the hybrid furnace (10) comprises at least one means (174) of atmospheric separation which, arranged at the level of the corset (160), is capable of separating the atmosphere of said at least one zone (1 10) of electric fusion, called cold vault, and the atmosphere of the zone (120) of flame fusion, called hot vault.

12. Furnace according to any one of claims 7 to 11, characterized in that the hybrid furnace (10) comprises blocking means (176) which are capable of retaining the vitrifiable mixture in said at least one electrical melting zone (110) so that said vitrifiable mixture present on the surface of the glass does not penetrate into the corset (160, 160A, 160B).

13. Oven according to any one of claims 7 to 12, characterized in that the hybrid oven (10) comprises means (500) for cooling the glass which are capable of cooling the glass in the corset (160), in particular at least one device (510) for cooling by air circulation.

14. Furnace according to any one of claims 1 to 13 taken in combination with claim 7, characterized in that the hybrid furnace (10) comprises an electric melting zone (110), said electric melting zone (110) being connected to the flame melting zone (120) located downstream by a corset (160).

15. Furnace according to claim 14, characterized in that the first charging device (610) for supplying vitrifiable mixture to said electric melting zone (1 10) is configured to spread the vitrifiable mixture in a uniform layer (1 12) on the surface (S) of the molten glass.

16. Furnace according to one of claims 14 or 15, characterized in that the second charging device (620) for supplying vitrifiable mixture to said flame melting zone (120) comprises a first charging unit (622) and a second charging unit (624) which are arranged transversely on either side of the melting zone (120). flames, preferably orthogonal to the longitudinal axis (A-A') of the oven.

17. Furnace according to any one of claims 1 to 13 taken in combination with claim 7, characterized in that the hybrid furnace (10) comprises at least a first electric melting zone (110A) and a second electric melting zone (110B), the first electric melting zone (110A) and the second electric melting zone (110B) being respectively connected to the flame melting zone (120) by a first corset (160A) and by a second corset (160B).

18. Furnace according to claim 17, characterized in that the first electric melting zone (110A) and the second electric melting zone (110B) are arranged transversely on either side of the flame melting zone (120), preferably arranged orthogonally to the longitudinal axis (A-A') of the furnace.

19. Furnace according to one of claims 17 or 18, characterized in that said first charging device (610) comprises a first charging unit (612) for supplying vitrifiable mixture to the first electric melting zone (110A) and a second charging unit (614) for supplying vitrifiable mixture to the second electric melting zone (110B).

20. Oven according to any one of claims 17 to 19, characterized in that the second charging device (620) is arranged longitudinally upstream of the flame melting zone (120).

21. Furnace according to any one of claims 1 to 20, characterized in that the vitrifiable mixture introduced into the furnace by the first charging device associated with said at least one electric melting zone (110) and the vitrifiable mixture introduced into the furnace by the second charging device associated with said flame melting zone (120) have a similar composition.

22. Oven according to any one of claims 1 to 21, characterized in that the hybrid oven (10) is capable of operating according to several operating modes, said operating mode of the oven being selectively chosen from: - a first electrical fusion operating mode in which the molten glass is produced solely by said at least one electrical fusion zone (110); - a second hybrid operating mode in which the molten glass is produced jointly by said at least one electric melting zone (110) and by said flame melting zone (120); - a third flame fusion operating mode in which the molten glass is produced solely by said at least one flame fusion zone (120).

23. Oven according to claim 22, characterized in that the hybrid oven (10) is capable of being controlled by an associated control unit (UC) to select one of said operating modes as a function of at least one selection parameter comprising: - an economic criterion which is a function of the respective cost of the electrical energy and the fuel also intended for the melting of the vitrifiable mixture; - an ecological criterion which is a function of the carbon footprint (CO2) respectively associated with the electrical energy and the said fuel, and - at least one technical criterion which is a function of the draw to be produced in relation to the quantity of molten glass capable of being obtained respectively by means of said at least one electric melting zone (110) and / or the flame melting zone (120) and / or a function of the composition of the glass to be manufactured, or even of the cullet content in the vitrifiable mixture.

24. Furnace according to any one of claims 1 to 23, characterized in that the first convection belt (210) and the second convection belt (220) are separated by a zone (230) of inversion of the belts (210, 220) determined by a hot point or source corresponding to the hottest point of the glass and in that the refining zone (200) comprises at least one burner (215) which is arranged to obtain said hot point determining said zone (230) of inversion of the belts in which a wall (260) is arranged.

25. Oven according to any one of claims 1 to 24, characterized in that the conditioning basin (310) of the zone (300) cooling comprises, from upstream to downstream, a corset (320) then an ember (330).

26. Method for manufacturing glass, in particular for supplying a glass float unit on a bath of molten metal, implemented in a hybrid furnace (10) according to any one of the preceding claims, characterized in that said method comprises at least one melting step carried out in the hybrid furnace (10) operating according to an operating mode of said furnace selectively chosen from: - a first electrical fusion operating mode in which the molten glass is produced solely by said at least one electrical fusion zone (110); - a second hybrid operating mode in which the molten glass is produced jointly by said at least one electric melting zone (110) and by said flame melting zone (120); - a third flame fusion operating mode in which the molten glass is produced solely by said at least one flame fusion zone (120).

27. Glass manufacturing method according to claim 26, characterized in that the method comprises, prior to the implementation of the melting step in the furnace, a determination step for selecting one of said operating modes as a function of at least one selection parameter comprising: - an economic criterion which is a function of the respective cost of the electrical energy and the fuel also intended for the melting of the vitrifiable mixture; - an ecological criterion which is a function of the carbon footprint (CO2) respectively associated with the electrical energy and the said fuel, and - at least one technical criterion which is a function of the draw to be produced in relation to the quantity of molten glass capable of being obtained respectively by means of said at least one electric melting zone (110) and / or the flame melting zone (120) and / or a function of the composition of the glass to be manufactured, or even of the cullet content in the vitrifiable mixture.

28. A method of manufacturing glass according to claim 27, characterized in that said step of determining the mode of operation of the hybrid oven (10) is carried out by means of a control unit (UC) which, associated with the hybrid oven (10), is capable of enabling it to be controlled.

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