Glass manufacturing method and hybrid glass furnace for carrying out said manufacturing method

Abstract

1. A method for producing glass, comprising: a step of melting a vitrifiable material for the purpose of producing glass, the vitrifiable material containing 0.5% to 10% carbon-containing organic matter; the step of melting the vitrifiable material is carried out in a hybrid glass furnace equipped with a hot-top vessel, the vessel comprising, from upstream to downstream, a first heating zone equipped with a combustion heating means and a second heating zone equipped with an electrode immersed in a bath of molten material; the melting step is carried out so that a proportion of combustion energy used to melt the vitrifiable material in the first zone is at least 50% and a proportion of electrical energy used to melt the vitrifiable material in the second zone is at least 50%; the first heating zone prioritizes the use of combustion energy to limit foaming in the first heating zone, while the second heating zone prioritizes the use of electrical energy, thereby maximizing the heating efficiency of each of the energies used in the furnace.

Description

[Technical Field]

[0001] The present invention belongs to the general field of glass production. More particularly, it relates to a production method comprising a step of melting a vitrifiable material to enable glass production. The present invention also relates to a hybrid glass furnace adapted to carry out said production method. The present invention finds a particularly advantageous, but by no means exclusive, application when the glass produced is a borosilicate glass.

[0002] In the present specification, "vitrifiable material" is understood to mean all materials that can be introduced into the composition fed to a glass furnace for the purpose of glass production, natural ores or synthetic products, materials originating from recycling, such as cullet.

[0003] Likewise, "glass" is understood to mean glass in the broad sense, ie including any material having a glass-ceramic or ceramic matrix in a glass-like form.

[0004] Furthermore, the term "manufacturing" includes the essential step of melting the vitrifiable material and, if necessary, all subsequent steps of subjecting the molten glass to fining / conditioning treatments for its final shaping, in particular in the form of flat glass (glazing), hollow glass (bottles, jars), mineral wool (in particular rock wool or glass wool) used for its thermal or sound insulation properties, or even optionally glass in the form of textile yarns used for reinforcement.

[0005] Various examples of furnace designs for melting vitrifiable material to obtain a bath of molten material, commonly referred to as a "batch mixture" or "composition," from which glass can be produced are known in the prior art. More specifically, to address environmental challenges, particularly the reduction of carbon dioxide (CO2) emissions, it is known to use fuel-fired furnaces (via burners) with supplementary electrical heating (via electrodes embedded in the bath). Furnaces of this design thus combine some energy from combustion, e.g., of fossil origin (generally gas), and some electrical energy. Such furnaces are also known as "hybrid" glass furnaces.

[0006] A conventional hybrid glass furnace comprises a hot-top vessel which is divided (virtually or physically by a suitable vertical wall) into two heating zones. "Heating zones" means parts of the vessel which are distributed from upstream to downstream with respect to the flow direction of the vitrifiable material introduced into the vessel and which differ from each other in the proportion of combustion energy (or electrical energy) used to heat the vitrifiable material.

[0007] More specifically, the current design of the vessels of hybrid glass furnaces essentially consists of an upstream heating zone, designed to melt the vitrifiable material and supplied primarily with electrical energy, and a downstream heating zone, designed more for the fining of the glass composition (i.e., to improve the glass quality, thereby reducing the number of unmelted particles in the glass as much as possible and reducing the number of bubbles in the glass as much as possible), supplied primarily with combustion energy.

[0008] This design optimizes heating efficiency (or heat transfer) in both the upstream and downstream heating zones of the hybrid glass furnace. Electrical energy is also preferred in the upstream heating zone for melting the vitrifiable material, since approximately 99% of the power is transferred to the glass bath through the electrodes. In comparison, much less power is transferred to the vitrifiable material by the burners in the upstream heating zone, approximately 60%, depending on the fuel / oxidant mixture, especially the oxygen content, and / or preheat use. This is one of the reasons why this type of hybrid glass furnace has become a benchmark in glass production.

[0009] During operation, glass furnaces routinely observe the occurrence of a "foaming" phenomenon on the surface of the molten bath. The presence of this foam is due in particular to the content of the vitrifiable material. For recycling purposes, the vitrifiable material typically contains post-consumer materials, such as household or flat cullet and / or glass wool (e.g., glass wool waste from manufacturing lines or end-of-life products). However, these post-consumer materials actually contribute to an increase in the proportion of carbon chains (e.g., organic contaminants on bottle cullet or binders in mineral wool) and sulfates in the bath. However, the foaming phenomenon is thermally activated, particularly, but not exclusively, near the electrodes, where sulfates are insolubilized by reaction with added carbon, thereby generating the foam.

[0010] The inventors have demonstrated that bubbles form heat shields that are particularly detrimental to the overall heating efficiency of such hybrid glass furnaces for reasons detailed below.

[0011] In the upstream heating zone, the use of primarily electrical energy for heating promotes the formation of bubbles, which form a heat shield at the interface between the glass bath and the floating unmelted vitrifiable material. As a result, this heat shield limits the transfer of heat generated by the electrodes to newly introduced vitrifiable material on the surface of the glass bath. These materials are therefore only partially melted within the bath, which makes tonnage management more complex and increases the risk of bath overflow outside the bath.

[0012] Bubbles may also be present in the downstream heating zone. This may be due to migration of bubbles from the upstream zone, and / or the presence of unmelted particles from the upstream heating zone that sustain the foaming phenomenon, and / or the high temperatures reached in this downstream zone. The issue of heat transfer from the burner to the bath is a major one, as this is where the combustion energy is primarily used. Bubbles form a heat shield between the burner and the glass bath that is being heated and refined in this downstream heating zone.

[0013] To illustrate the effect of the shielding caused by the presence of the bubbles forming this heat shield, a non-limiting example is given below: For an overhead burner, 200 kW / m 2 For a power input of about 40 kW / m, the amount transferred to the glass bath in the presence of the bubbles forming this heat shield is about 40 kW / m. 2 (+ / -10kW / m 2 ), whereas, in contrast, for vitrifiable material present on the surface of the glass bath, the power input is estimated to be about 120 kW / m 2 (+ / -10kW / m 2 ) with a power input of 200 kW / m 2 For an electrode with a 2 is transferred to the glass bath (this is due to the above-mentioned design of the glass hybrid furnace), the inventors have found that, also in this case, due to the heat shield formed by the bubbles, only about 40 kW / m is transferred to the glass material to be melted present on the surface of the bath. 2 (approx. + / - 10kW / m 2) is estimated to be the only

[0014] Therefore, this limitation of the overall heating efficiency of the hybrid furnace means that the foaming phenomenon hinders the use of cullet and / or glass wool-based products as vitrifiable materials, i.e., for recycling. In other words, foaming limits the recycling capacity of the hybrid furnace and also leads to significantly increased energy consumption or even elevated temperatures, which contribute to premature wear of the furnace refractories.

[0015] Current attempts to mitigate this foaming problem are far from optimal, requiring measures such as the addition of solid oxidizers, such as sodium nitrate (NaNO3) and manganese oxide (MnO2). Indeed, the use of oxidizers is itself limited by NOx emissions, among other factors, and the need to maintain the glass object's significant biosolubility. As a result, increasing the amount of oxidizer is not feasible, which effectively limits the recycling of vitrifiable materials.

[0016] It should be noted that the above-mentioned bubbling phenomenon is present whatever the composition of the vitrifiable material, but is all the more particularly problematic (in terms of the amount of bubbles generated) when the glass being produced is a borosilicate glass. Summary of the Invention [Problem to be solved by the invention]

[0017] The object of the present invention is to remedy some or all of the drawbacks of the prior art, in particular those disclosed above, by proposing a solution that maximizes the heating efficiency (or heat transferability) of each of the energies used (combustion, electricity) and the recycling capacity in a hybrid furnace. [Means for solving the problem]

[0018] To this end, according to a first aspect, the present invention provides a method for producing glass, comprising a step of melting a vitrifiable material intended for producing said glass, said vitrifiable material containing a carbon-containing organic substance in a proportion of 0.5% to 10%, said melting step of said vitrifiable material being carried out in a hybrid glass furnace equipped with a hot-top vessel, said vessel being arranged in the following order from upstream to downstream: - a first heating zone provided with combustion heating means; - a second heating zone with an electrode immersed in a bath of molten material; Equipped with The melting step is carried out so that at least 50% of the combustion energy is used to melt the vitrifiable material in the first zone and at least 50% of the electrical energy is used to melt the vitrifiable material in the second zone, and the method prioritizes the use of combustion energy in the first heating zone to limit foaming in the first heating zone, and conversely prioritizes the use of electrical energy in the second heating zone, thereby maximizing the heating efficiency of each of the energies used in the furnace.

[0019] Advantageously, the prioritization of combustion energy in the first heating zone and conversely the prioritization of electrical energy in the second heating zone during the melting process is determined according to the proportion of carbonaceous organic matter contained in the vitrifiable material.

[0020] According to one of its important features, the method for producing glass according to the invention involves, for those skilled in the art, a paradigm shift in the design of glass furnaces used in its implementation. Indeed, as mentioned above, the design of hybrid glass furnaces according to the prior art was based on the principle of using electrical energy in the upstream heating zone and combustion energy in the downstream heating zone due to the heat transfer efficiencies that can be obtained in each case.

[0021] Therefore, one skilled in the art would be discouraged from making such improvements to furnace designs, especially when the practice of the present invention leads one to the exact opposite situation, using electrical and combustion energy in each heating zone of the vessel, unexpectedly reversing the dominant energies of each.

[0022] The manufacturing method according to the invention therefore makes it possible to give priority to the use of combustion energy in the first heating zone and, conversely, to the use of electrical energy in the second heating zone.

[0023] This significantly reduces the risk that sulfates contained in the vitrifiable material will interact with the carbon chains contained in the vitrifiable material and avoids the presence of localized spots of very high temperature in the glass, which in turn advantageously limits foaming in the first heating zone.

[0024] Furthermore, when bubbles are formed, the primary heating means (burner or electrode) in each zone is not separated from the object to be heated by a thermal screen, i.e., a layer of bubbles forming a screening or thermal screen, as has existed in the prior art.

[0025] As a result, the present invention maximizes the heating or heat transfer efficiency of each of the energies used in the furnace, which in fact significantly limits the occurrence of bubbles in the first heating zone, as well as the problem of insufficient heat transfer between the bath and the vitrifiable material, thereby significantly facilitating the melting of the vitrifiable material introduced into the vessel.

[0026] In the second heating zone, where the energy used is mainly electrical, the glass bath is substantially free of carbonaceous vitrifiable material and sulfates, so electrical heating is very efficient without the risk of poor heat transfer.

[0027] Furthermore, the formation of bubble residue on the surface of the bath in the second heating zone does not adversely affect glass production. Instead, the bubble residue forms a heat shield against the heat generated below the bath surface by the electrodes, which contributes to good thermal insulation of the bath. The heat shield formed by the bubbles, which was previously a disadvantage in second heating zones equipped with burners, is now an advantage in second heating zones equipped with electrodes.

[0028] In certain embodiments, the melting method may further comprise one or more of the following features, either alone or in any technically possible combination:

[0029] In certain embodiments, the percentage of combustion energy used to melt the vitrifiable material in the first zone is at least 60% and the percentage of electrical energy used to melt the vitrifiable material in the second zone is at least 60%.

[0030] In certain embodiments, the percentage of combustion energy used in the first zone is at least 70%.

[0031] In certain embodiments, the melting energy used in the first zone is combustion energy only.

[0032] In certain embodiments, the first heating zone further comprises an electrode immersed in the bath of molten material, and the melting process is carried out such that the rate of electrical energy used in the first zone allows the bath temperature to be maintained above a given temperature, for example, the glass devitrification temperature.

[0033] In certain embodiments, the percentage of electrical energy used in the second zone is at least 70%.

[0034] In certain embodiments, the melting energy used in the second zone is solely electrical energy.

[0035] In certain embodiments, the second heating zone further comprises a combustion heating means and the melting process is carried out such that the proportion of combustion energy used in the second zone makes it possible to maintain the temperature of the crown at a given temperature, for example, above the condensation temperature of sodium borate.

[0036] In certain embodiments, the proportion of combustion energy used in the first zone and the proportion of electrical energy used in the second zone are equal.

[0037] In certain embodiments, the rate of combustion energy used in the first zone and the rate of electrical energy used in the second zone are different, one being greater than the other or vice versa.

[0038] In certain embodiments, the combustion energy in the first and / or second zones is obtained by combustion of hydrogen.

[0039] In certain embodiments, the vitrifiable material is selected to allow for the production of borosilicate glass.

[0040] In certain embodiments, the percentage of carbonaceous organic matter in the vitrifiable material that is less than or equal to 10% is between 0.75% and 10%, more preferably between 1% and 10%, and even more preferably between 2% and 10%.

[0041] In certain embodiments, the vitrifiable material comprises recycled material, eg, cullet, eg, up to 90% and / or mineral wool, eg, up to 100%.

[0042] In certain embodiments, combustion fumes generated in the first heating zone are discharged toward a second heating zone to an exhaust chimney located downstream in the second heating zone, thereby enabling the fumes to maintain a crown temperature in the second heating zone above a given temperature, in particular the condensation temperature of sodium borate.

[0043] According to a second aspect, the present invention relates to a hybrid glass furnace adapted to carry out a method for producing glass, said furnace comprising a control unit for controlling combustion heating means in at least a first heating zone and electrodes immersed in a bath of molten material in a second heating zone, respectively, depending on the proportion of carbonaceous organic matter contained in the vitrifiable material, wherein the use of combustion energy in the first heating zone is prioritized, thereby limiting foaming in said first heating zone, and conversely the use of electrical energy is prioritized in the second heating zone, thereby maximizing the heating efficiency of each of the energies used in the furnace.

[0044] In certain embodiments, the hybrid glass furnace may further comprise one or more of the following features, either alone or in any technically feasible combination:

[0045] In certain embodiments, the furnace comprises a vertical partition wall, the vertical partition wall comprising: - blocking the flow of melt between the first and second zones on the surface of the bath of molten material; - circulating the melt between the first and second zones in the furnace floor; It is structured as follows.

[0046] The partition wall (due to its adapted height) can prevent the circulation of molten material between the zones at the surface of the bath of molten material, which advantageously prevents bubbles generated in the second heating zone from migrating to the first heating zone. In other words, the presence of the vertical partition wall further optimizes the heating efficiency of the hybrid furnace.

[0047] In certain embodiments, the crown height of the second heating zone is less than the crown height of the first heating zone.

[0048] In certain embodiments, the bath height of the second heating zone is less than the bath height of the first heating zone.

[0049] In certain embodiments, the furnace further comprises an exhaust chimney disposed downstream of the second heating zone and configured to exhaust combustion fumes generated in the first heating zone to the second heating zone. [Brief explanation of the drawings]

[0050] Other features and advantages of the present invention will become apparent from the non-limiting description given below, with reference to the accompanying drawings, which illustrate exemplary embodiments thereof. [Figure 1] 1 shows a schematic representation of a particular embodiment of a hybrid glass furnace according to the invention; FIG. [Figure 2] 2 shows a schematic diagram of another embodiment of a hybrid glass furnace according to the present invention; FIG. [Figure 3] FIG. 2 shows a schematic diagram of yet another embodiment of a hybrid glass furnace according to the present invention. [Figure 4] FIG. 2 shows a schematic diagram of yet another embodiment of a hybrid glass furnace according to the present invention. [Figure 5] FIG. 2 shows a schematic diagram of yet another embodiment of a hybrid glass furnace according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0051] Figure 1 1 shows a schematic representation of one particular embodiment of a glass furnace 100 according to the invention in its environment. In particular, FIG. 1 shows a side view of the furnace 100.

[0052] In the remainder of the description, the longitudinal, vertical and transverse orientations are used without limitation with respect to the axis system (L, V, T) shown in the figures.

[0053] By convention, the terms "upstream" and "downstream" and "left" and "right" are used in reference to a longitudinal orientation. The terms "upper" and "lower" or "top" and "bottom" or "above" and "below" are used in reference to a longitudinal orientation.

[0054] More specifically, the terms "upstream" and "downstream" as used herein correspond to the direction of glass flow in the furnace, where the glass flows from upstream to downstream, or in other words, from left to right with respect to the illustration of furnace 100 in FIG. 1 .

[0055] In accordance with the present invention, furnace 100 includes a hot-top vessel 110, which is typically made of a refractory material, such as alumina-zirconia-silica or chromium.

[0056] The concept of a "hot top" in a glassmaking furnace is well known to those skilled in the art and will not be further described here. It should be noted that, according to the present design, the vitrifiable material is introduced into the vessel 110 from the side (i.e., along its longitudinal orientation) by a loading device (not shown), also known as a "loader."

[0057] 1, the vessel 110 has a horizontally extending bottom wall 111, which forms the floor of the furnace 100. Similarly, according to other embodiments, nothing prevents the conceivable lower wall being inclined with respect to the horizontal plane, for example in the form of a downwardly pointing cone or in the form of an inclined surface, in order to facilitate the driving of the molten vitrifiable material towards the bottom of the vessel 110 at the start of melting.

[0058] The furnace 100 is configured to melt a vitrifiable material introduced into a vessel 110 to form a bath 120 of molten vitrifiable material. Such molten material is intended for glass production, and for this purpose the furnace 100 is integrated into a glass production facility that includes various devices (not shown) capable of carrying out glass fining and / or homogenization and / or thermal conditioning and / or final forming processes in zones other than the zone in which the furnace 100 is implemented. Such processes are well known to those skilled in the art and will not be described further here.

[0059] The remainder of this specification will assume, but is not limited to, that the glass intended for production from the molten material in furnace 100 is a borosilicate glass. However, the assumption of such glass production is merely one variation of the present invention. Thus, in general, there is no limitation on the type of glass that may be produced using the melt in furnace 100 according to the present invention.

[0060] It should be noted that the compositions of vitrifiable materials from which borosilicate type glasses can be produced are well known to those skilled in the art and will therefore not be described in detail here. This observation naturally also applies to all other types of glass that can be produced according to the invention. Furthermore, aspects relating to the proportion of carbonaceous organic matter that can be contained in the vitrifiable materials used will be described in more detail below.

[0061] According to the invention, the glass furnace 100 is of the hybrid type, in other words, the vitrifiable material in the vessel 110 is melted to form the bath 120 using two different energy sources, namely combustion energy and electrical energy, respectively. Each of these energies is provided by suitable heating means of a type known per se, namely: - for combustion energy, an overhead burner arranged between the furnace crown 110 and the surface of the bath 120, and For electrical energy, electrodes made of a refractory material such as molybdenum and embedded in the bath 120 Used by.

[0062] Combustion can be achieved in a known manner by combining different types of fuel with an oxidizer. Thus, oxygen from air is generally used as the oxidizer, and oxygen-enriched air can be obtained by oxygen-enriching this air. Pure oxygen can also be used as an oxidizer in the special case of oxy-fuel combustion.

[0063] With respect to combustion, the fuel used is generally natural gas or possibly other fossil fuels, for example petroleum products such as heating oil.

[0064] Naturally, the use of fossil fuels has a direct impact on the carbon footprint of glass production, particularly with regard to carbon dioxide (CO2) emissions generated by combustion. To improve this carbon balance, it is possible to use green fuels as an alternative to fossil fuels, in particular biogas, a gas essentially consisting of methane and carbon dioxide produced by methanation.

[0065] Alternatively, the fuel used in all or part of the furnace 100 may be hydrogen (H2), which has the advantage of being carbon-free compared to biogas.

[0066] In its general principle, the hybrid furnace 100 differs from prior art hybrid furnaces in that the vessel 110 comprises, from upstream to downstream, two heating zones, namely a first heating zone Z_1 and a second heating zone Z_2, which are configured to carry out the melting step of the vitrifiable material of the method for producing glass according to the invention (not shown).

[0067] The step of melting a vitrifiable material intended for the production of glass, the vitrifiable material containing a proportion of carbonaceous organic matter between 0.5% and 10%, is carried out as follows: the proportion of combustion energy used to melt the vitrifiable material in the first zone Z_1 is at least 50% (i.e., the total melting energy used in the first zone Z_1 to melt the vitrifiable material includes at least 50% combustion energy), and the proportion of electrical energy used to melt the vitrifiable material in the second zone Z_2 is at least 50% (i.e. the total melting energy used in the second zone Z_2 to melt the vitrifiable material comprises at least 50% electrical energy).

[0068] More specifically, in the embodiment described herein, the two heating zones Z_1, Z_2 are in fluid communication and there is no barrier between them.

[0069] Furthermore, each of the heating zones Z_1, Z_2 is advantageously configured to allow for the use of combustion energy and electrical energy. As shown in Figure 1, the first heating zone Z_1 comprises three overhead burners 130_1, 130_2, 130_3 and two electrodes 140_1, 140_2, while the second heating zone Z_2 comprises a single overhead burner 150 and four electrodes 160_1, 160_2, 160_3, 160_4.

[0070] The burners 130_1, 130_2, 130_3, 150 are generally so-called horizontal burners, since they are arranged in a horizontal direction perpendicular to the flow of glass in the furnace 100.

[0071] 1, electrodes 140_1, 140_2, 160_1, 160_2, 160_3, 160_4 are generally so-called vertical electrodes, as they are positioned vertically from the bottom 111 of the vessel 110. However, one or more of the electrodes may have a different orientation, such as being a tilted electrode.

[0072] However, the assumption of such a number of burners and electrodes in each of the heating zones Z_1 and Z_2 is merely one of the variations of the present invention. In general, there is no limit to the number of burners and electrodes in each heating zone, as long as the proportion of combustion energy (or electrical energy) used in the first zone Z_1 (or the second zone Z_2) is at least 50%.

[0073] Thus, by implementing the melting step of such a glass manufacturing method using the hybrid furnace 100, it is possible to limit foaming in the first heating zone Z_1 by prioritizing the use of combustion energy in the first heating zone Z_1, and conversely, to prioritize the use of electrical energy in the second heating zone Z_2, thereby maximizing the heating efficiency (i.e., heat transfer) of each of this energy used in the furnace 100.

[0074] This significantly reduces the risk that sulfates contained in the vitrifiable material will become insoluble near the electrodes in the first heating zone Z_1 and interact with the carbon chains contained in the vitrifiable material, which in turn advantageously limits the effect of foaming in the first heating zone Z_1 and thus the heat shields formed by this foam.

[0075] As a result, the present invention maximizes the heating efficiency of each of the energy sources used in the furnace 100. Indeed, the occurrence of bubbles in the first heating zone Z_1 is significantly limited, as are the problems of insufficient heat transfer between the bath and the vitrifiable material, which in turn significantly facilitates the melting of the vitrifiable material introduced into the vessel 110.

[0076] According to the present invention, the energy source (combustion or electricity) is advantageously never separated from the object to be heated by the bubbles, whatever the object may be, thereby remedying the drawbacks of the prior art described in the preamble, caused by the screening or thermal screen formed by the bubbles.

[0077] Indeed, bubbles, at least in the first heating zone, do not rise above the vitrifiable material to be melted and therefore no longer form a thermal screen, so that the melting, which according to the invention is achieved mainly by means of burners, is no longer affected. Similarly, in the second heating zone, where heating and fining are mainly carried out by means of electrodes, the presence of possible bubbles no longer acts as a thermal barrier to the (electrical) energy source, as in the prior art using burners.

[0078] In the second heating zone Z_2, where the energy used is primarily electrical, the bath 120 is substantially free of carbonaceous materials and sulfates, so electrical heating is highly efficient without the risk of poor heat transfer. Furthermore, even if a bubble residue does form on the surface of the bath 120 in the second heating zone Z_2 (e.g., as shown in FIG. 1), this does not adversely affect glass production. Rather, this bubble residue forms a heat shield against the heat generated below the bath surface 120 by the electrodes, which contributes to good thermal insulation of this bath 120.

[0079] In one more specific exemplary embodiment of the melting process, the proportion of combustion energy used to melt the vitrifiable material in the first zone is at least 60% and the proportion of electrical energy used to melt the vitrifiable material in the second zone is at least 60%.

[0080] According to a more specific exemplary embodiment of the melting process, the proportion of combustion energy used in the first zone Z_1 is at least 70%, for example, the proportion of combustion energy used in the first zone Z_1 is 75% or 85%.

[0081] The melting process can also be carried out in such a way that the proportion of electrical energy used in the first zone Z_1 makes it possible to maintain the bath temperature in the first zone Z_1 above a given temperature, for example above the glass devitrification temperature.

[0082] Generally, there is no limit to the proportion of combustion energy used in zone Z_1 as long as it is 50% or more. Therefore, for example, there is no prohibition on using only combustion energy as the melting energy in first zone Z_1 (i.e., proportion of combustion energy = 100%). In this regard, it is understood that the presence of an electrode in first heating zone Z_1 is not essential to the present invention.

[0083] In the second heating zone Z_2, in addition to the above example of the proportion of combustion energy used in the first heating zone Z_1, the proportion of electrical energy is at least 70%, for example, the proportion of electrical energy used in the second zone Z_2 is 75% or 85%.

[0084] In a more specific embodiment, the melting process may be carried out such that the proportion of combustion energy used in the second zone Z_2 allows the temperature of the crown to be maintained above a given temperature.

[0085] By way of example, this temperature corresponds to the sodium borate condensation temperature of approximately 1200° C. This compound is known to exhibit corrosive properties and can condense on the crown walls if the temperature above the bath 120 is not sufficient.

[0086] Generally, there is no limit to the proportion of electrical energy used in the second zone Z_2 as long as it is 50% or more. Therefore, for example, there is no prohibition on the melting energy used in the second zone Z_2 being electrical energy only (i.e., the proportion of electrical energy = 100%). In this respect, it is understood that the presence of a burner in the second heating zone Z_2 is not essential to the present invention.

[0087] In addition to or instead of maintaining the crown temperature above a given temperature by adjusting the combustion energy used in the second heating zone Z_2, the furnace may further comprise an exhaust chimney 180 configured to exhaust combustion fumes generated in the first heating zone Z_1 to the second heating zone Z_2.

[0088] Advantageously, the chimney 180 is located in or connected to the downstream portion of the second heating zone Z_2. However, there are no limitations on the configuration (shape, geometry, location) of this chimney 180, which can take the form of, for example, an opening cut into the crown of the vessel 110, thereby forming a fume exhaust passage.

[0089] Such a chimney 180 may also allow the temperature in the second zone Z_2 to be maintained above a given temperature through the discharge of fumes into the second zone Z_2, and may therefore also help to avoid the corrosive effects associated with the condensation of sodium borate on the crown of the furnace 100.

[0090] Advantageously, by circulating the fumes (generated in the first heating zone Z_1) in the second heating zone Z_2 before discharging them downstream through the chimney 180, it is possible to maintain the crown temperature higher than a given temperature, such as the condensation temperature of sodium borate, and may even avoid the use of burner 130_4, which in turn helps to reduce the crown height of the second heating zone Z_2 of the furnace 100, among other things.

[0091] As mentioned above, the melting step of the glass manufacturing method according to the present invention maximizes the heating efficiency of each of the energy used in the furnace 100. Therefore, the present invention allows for the use of more recycled material than was the case in the prior art, thereby maximizing the recycling capacity of the furnace 100.

[0092] Thus, according to one particular embodiment of the melting process, the vitrifiable material introduced into the vessel 110 contains less than or equal to 10% carbonaceous organic matter.

[0093] According to one important feature of the present invention, the vitrifiable material intended for the production of glass contains a proportion of carbonaceous organic matter between 0.5% and 10%, preferably between 0.75% and 10%, more preferably between 1% and 10%, and even more preferably between 2% and 10%.

[0094] Vitrifiable materials intended for the production of glass may contain recycled materials, such as cullet (e.g. household cullet, milk cullet, etc.), for example in proportions of up to 90% and / or mineral wool in proportions of up to 100% (e.g. a glass filling equivalent to 100% recycled glass wool, which may contain up to 10% binder).

[0095] The furnace 100 comprises a control unit UC for controlling the combustion heating means 130_1, 130_2, 130_3 in the first heating zone Z_1 and the electrodes 160_1, 160_2, 160_3, 160_4 immersed in the bath 120 of molten material in the second heating zone Z_2, respectively, depending on the proportion of carbonaceous organic matter contained in the vitrifiable material.

[0096] Preferably, according to a first embodiment, when the vitrifiable material contains a proportion of carbonaceous organic matter of the order of 0.5%, during the melting step, the proportion of combustion energy used to melt the vitrifiable material in the first heating zone Z_1 is 50% and the proportion of electrical energy used to melt the vitrifiable material in the second heating zone Z_2 is 50%. In other words, the proportions of combustion energy and electrical energy are equal to 50% in each of these heating zones Z_1; Z_2.

[0097] Alternatively, the proportion of combustion energy and the proportion of electrical energy are not equal, for example, the proportion of combustion energy in the first heating zone Z_1 is 50% and the proportion of electrical energy in the second heating zone Z_2 is greater than 50%, for example 70% or even 100%.

[0098] Alternatively, it is of course possible for the proportion of combustion energy in the first zone Z_1 to be greater than the proportion of electrical energy in the second zone Z_2, in particular for the proportion of electrical energy to be 50% and the proportion of combustion energy to be greater than 50%, for example 70% or even 100%.

[0099] Preferably, according to a second embodiment, when the vitrifiable material contains a proportion of carbonaceous organic matter of the order of 5%, during the melting step, the proportion of combustion energy used to melt the vitrifiable material in the first heating zone Z_1 is 75%, and the proportion of electrical energy used to melt the vitrifiable material in the second heating zone Z_2 is 75%. In other words, in such a case, the proportion of combustion energy and the proportion of electrical energy are 75% in each of these heating zones Z_1; Z_2, respectively.

[0100] Preferably, when the vitrifiable material contains a proportion of carbonaceous organic matter of 10%, during the melting step, the proportion of combustion energy used to melt the vitrifiable material in the first heating zone Z_1 is 100% and the proportion of electrical energy used to melt the vitrifiable material in the second heating zone Z_2 is 100%.

[0101] In other words, in such a case, the proportion of combustion energy and the proportion of electrical energy are 100% in each of the heating zones Z_1 and Z_2, respectively.

[0102] According to the variant just described for the first embodiment, the proportion of combustion energy and the proportion of electrical energy may be different in the second or third embodiment, one being greater than the other and vice versa, and each of said energy proportions being at least 50%.

[0103] The control unit UC can control the furnace 100 by prioritizing the use of combustion energy in the first heating zone Z_1 to limit foaming in this first heating zone Z_1 and conversely prioritizing the use of electrical energy in the second heating zone Z_2, thereby maximizing the heating efficiency (i.e., heat transfer) of each of these energies used in the furnace 100.

[0104] In contrast to the design shown in Figure 1, other designs shown in Figures 2 to 5 are described below. In this case, neither a control unit UC nor even an exhaust chimney is shown, but this is only for the sake of simplicity. Naturally, the furnaces shown in Figures 2 to 5 can further comprise a control unit UC for controlling the energy prioritization or even an exhaust chimney for exhausting combustion fumes.

[0105] The hybrid furnace according to the invention has been described so far assuming a particular geometry in which there is no physical separation between the two heating zones Z_1, Z_2, but other alternatives are possible.

[0106] Figure 2 2 shows, in its environment, another particular embodiment of a glass furnace 200 according to the invention.

[0107] 1, the hybrid furnace 200 comprises a vessel 210 in which a bath 220 is formed by melting a vitrifiable material intended for glass production. More specifically, the vessel 220 comprises two heating zones Z_1 and Z_2 from upstream to downstream, and the process of melting the vitrifiable material is carried out as follows: - three overhead burners 230_1, 230_2, 230_3 and two electrodes 240_1, 240_2 in the first heating zone Z_1, - an overhead burner 250 and four electrodes 260_1, 260_2, 260_3, 260_4 in a second heating zone Z_2;

[0108] Furthermore, in this other embodiment, as shown by way of non-limiting example in FIG. 2, the furnace comprises a vertical partition 270, which comprises: - blocking the flow of melt between the first zone Z_1 and the second zone Z_2 on the surface of the bath 220 of molten material, - circulating the melt between the first zone Z_1 and the second zone Z_2 in the floor 211 of the furnace 200; It is structured as follows.

[0109] The vertical partitions 270 are, for example, made of a refractory material, for example, magnesia and / or chromium, or an alumina zirconia silica type material (whether or not produced by a fusion casting process).

[0110] Alternatively, the vertical bulkhead 270 may comprise an outer metal casing (also known as an "armature") formed by two bulkheads (walls called "water jackets") through which a cooling fluid, such as water, flows.

[0111] In other words, the vertical partition 270 is configured to form an opening at the bottom of the furnace 200, allowing the molten material in the first heating zone Z_1 to flow toward the second heating zone Z_2 and then be discharged from the furnace 200.

[0112] It should be noted that the partition 270 (due to its adapted height) can prevent the circulation of molten material between zones Z_1, Z_2 at the surface of the bath 220 of molten material, thereby advantageously preventing bubbles generated in the second heating zone Z_2 from migrating to the first heating zone Z_1. In other words, the presence of the vertical partition 270 further optimizes the heating efficiency of the hybrid furnace 200.

[0113] As mentioned above, it is possible to envision that the melting energy used in the first zone Z_1 is solely combustion energy (i.e., proportion of combustion energy = 100%). Such an arrangement is advantageous in the context of the present embodiment in that it promotes the generation of convective motion within the bath 220, aiding in the circulation of molten material between the first zone Z_1 and the second zone Z_2 at the floor 211 of the furnace 200.

[0114] If the furnace 200 is equipped with a fume exhaust chimney similar to 180 shown in FIG. 1, the vertical partition 270 has at least one opening (not shown) at the top to allow the fumes to flow from the first heating zone Z_1 to the second heating zone Z_2 up to this exhaust chimney located downstream.

[0115] Figures 3 and 4 3 shows diagrammatically in its environment another particular embodiment of a glass furnace 300, 400 according to the invention.

[0116] In particular, furnace 300 (or furnace 400) differs from furnace 100 of FIG. 1 (or furnace 200 of FIG. 2) in that the crown height of second heating zone Z_2 is lower than the crown height of first heating zone Z_1.

[0117] The hybrid furnace according to the present invention has been described up to this point on the assumption that the bath height in the first zone Z_1 is the same as the bath height in the second zone Z_2. However, this configuration does not limit the present invention, and does not exclude the possibility of an embodiment in which the bath height in the second zone Z_2 is lower than the bath height in the first zone Z_1. Although there is such a difference in bath height between zones Z_1 and Z_2, the minimum bath height in the second zone Z_2 can be, for example, 200 mm to 300 mm.

[0118] The lower glass height in the second zone Z_2 advantageously minimizes the amount of refractory material, thereby reducing furnace construction costs. Additionally, minimizing heat loss through the refractory walls reduces the volume of glass to be heated, thereby minimizing energy demands.

[0119] Preferably, when the bath height in the second zone Z_2 is lower than the bath height in the first zone Z_1, the melting energy used in the second zone Z_2 is only electrical energy, which may make it possible to design the second zone Z_2 so that its crown height is flush with the surface of the bath.

[0120] Non-limiting examples include: Figure 5 5 shows a schematic representation of another embodiment of a hybrid glass furnace 500 according to the present invention, in which the bath height in the second zone Z_2 is lower than the bath height in the first zone Z_1. As can be seen in FIG. 5, the height of the floor of the furnace 500 differs between zones Z_1 and Z_2, thereby allowing the desired difference in bath height to be achieved in this embodiment.

[0121] According to yet another aspect, the present invention also encompasses a glass manufacturing method (details not shown) which, in addition to the step of melting the vitrifiable material, also includes a step of final shaping of the glass, which, according to more specific exemplary embodiments, may be preceded by a fining step and / or a homogenization step and / or a thermal conditioning treatment step from the molten material flowing from the vessel.

Claims

1. A method for producing glass, the method comprising a step of melting a vitrifiable material intended for producing the glass, the vitrifiable material containing 0.5% to 10% of carbon-containing organic matter, the step of melting the vitrifiable material being carried out in a hybrid glass furnace (100) equipped with a hot-top vessel (110), the vessel being arranged in the following order from upstream to downstream: a first heating zone (Z_1) equipped with combustion heating means (130_1, 130_2, 130_3), a second heating zone (Z_2) equipped with electrodes (160_1, 160_2, 160_3, 160_4) immersed in the bath (120) of molten material; Equipped with the melting step is carried out such that a proportion of combustion energy used to melt the vitrifiable material in the first zone is at least 50% and a proportion of electrical energy used to melt the vitrifiable material in the second zone is at least 50%, and the method prioritizes the use of the combustion energy in the first heating zone (Z_1) to limit foaming in the first heating zone (Z_1), and conversely, prioritizes the use of the electrical energy in the second heating zone (Z_2), thereby maximizing the heating efficiency of each of the energies used in the furnace.

2. 2. The method of claim 1, wherein the proportion of the combustion energy used in the first zone (Z_1) is at least 70%.

3. 3. The method of claim 2, wherein the melting energy used in the first zone (Z_1) is combustion energy only.

4. 3. The method according to claim 1, wherein the first heating zone (Z_1) further comprises electrodes (140_1, 140_2) immersed in the bath of molten material, and the melting process is carried out in such a way that the proportion of electrical energy used in the first zone (Z_1) makes it possible to maintain the bath temperature in the first zone (Z_1) at a given temperature, for example above the glass devitrification temperature.

5. 5. The method according to any one of claims 1 to 4, wherein the proportion of electrical energy used in the second zone (Z_2) is at least 70%.

6. 6. The method according to claim 5, wherein the melting energy used in the second zone (Z_2) is electrical energy only.

7. 6. The method according to any one of claims 1 to 5, wherein the second heating zone (Z_2) further comprises combustion heating means (130_4), and the melting step is carried out in such a way that the proportion of the combustion energy used in the second zone (Z_2) makes it possible to maintain the temperature of the crown in the second zone (Z_2) at a given temperature, for example above the condensation temperature of sodium borate.

8. 8. The method according to any one of claims 1 to 7, wherein the proportion of combustion energy used in the first zone (Z_1) and the proportion of electrical energy used in the second zone (Z_2) are equal or different, one greater than the other or vice versa.

9. 9. The method according to any one of claims 1 to 8, wherein the combustion energy in the first zone (Z_1) and / or the second zone (Z_2) is obtained by combustion of hydrogen.

10. A method according to any one of claims 1 to 9, wherein the vitrifiable material is selected to allow the production of borosilicate glass.

11. 11. The method according to any one of claims 1 to 10, wherein the proportion of carbonaceous organic matter in the vitrifiable material, which is less than or equal to 10%, is between 0.75% and 10%, more preferably between 1% and 10%, and even more preferably between 2% and 10%.

12. 12. The method according to any one of claims 1 to 11, wherein the vitrifiable material comprises recycled material, for example cullet, for example in a proportion of up to 90% and / or mineral wool in a proportion of up to 100%.

13. 13. The method according to any one of claims 1 to 12, wherein combustion fumes generated in the first heating zone (Z_1) are discharged towards the second heating zone (Z_2) to an exhaust chimney (180) arranged downstream in the second heating zone (Z_2), whereby the fumes make it possible to maintain the temperature of the crown in the second heating zone (Z_2) at a given temperature, in particular above the condensation temperature of sodium borate.

14. A hybrid glass furnace (100, 200, 300, 400, 500) configured to carry out the method for producing glass according to any one of claims 1 to 13, said furnace comprising a control unit (UC), said control unit (UC) controlling at least the combustion heating means (130_1, 130_2, 130_3) in the first heating zone (Z_1), the electrodes (160_1, 160_2, 160_3, 160_4) immersed in the bath of molten material (120) in the second heating zone (Z_2), and (b) controlling the ratio of the carbonaceous organic matter contained in the vitrifiable material to the ratio of the carbonaceous organic matter contained in the vitrifiable material, wherein the use of the combustion energy in the first heating zone (Z_1) is prioritized to limit foaming in the first heating zone (Z_1), and conversely the use of the electrical energy in the second heating zone (Z_2) is prioritized, thereby maximizing the heating efficiency of each of the energies used in the furnace.

15. The furnace is provided with a vertical partition wall (270), the vertical partition wall (270) comprising: - blocking the flow of melt between the first and second zones (Z_1, Z_2) on the surface of the bath of molten material, - circulating the melt between the first and second zones in the floor (211) of the furnace; The furnace (200) of claim 14, configured to:

16. 16. The furnace (300, 400) of claim 14 or 15, wherein the crown height of the second heating zone (Z_2) is less than the crown height of the first heating zone (Z_1).

17. The furnace (500) according to any one of claims 14 to 16, wherein the bath height of the second heating zone (Z_2) is lower than the bath height of the first heating zone (Z_1).

18. The furnace according to any one of claims 14 to 17, further comprising an exhaust chimney (180), the exhaust chimney (180) being arranged in a downstream portion of the second heating zone (Z_2) and configured to exhaust combustion fumes generated in the first heating zone to the second heating zone.

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