Glass melting process with very low to zero CO2 emissions

Abstract

The present invention relates to a process for melting vitrifiable material to produce sheet glass, comprising the steps of: (i) providing a furnace comprising at least one melting tank having electric heating means, a refining tank having oxyfuel heating means, a neck separating the melting tank and the refining tank, an inlet means arranged in the melting tank, and an outlet means arranged downstream of the refining tank; (ii) charging vitrifiable material including raw materials and cullet into the melting tank by means of the inlet means, the amount of cullet being at least 10% by weight of the total amount of vitrifiable material; (iii) melting the vitrifiable material in the melting tank by heating with the electric heating means; (iv) refining the melt in the refining tank by heating with the oxyfuel heating means supplied with gas and / or hydrogen; (v) flowing the melt from the refining tank through the outlet means to a working zone; (vi) capturing CO2 from an exhaust gas having a CO2 concentration of at least 35%, the electrical input rate being in the range of 50% to 85%, and the step of capturing CO2 comprising a compression and / or dehydration step. This process exhibits a very low CO2 fingerprint and is economically viable.

Description

[Technical field]

[0001] The present invention relates to a glass melting process intended to continuously supply molten glass to a flat glass forming installation such as a float or rolling installation. In particular, the present invention relates to a glass melting process which offers many advantages, especially in terms of CO2, especially its emission and capture.

[0002] The invention relates more particularly, but not exclusively, to flat glass melting processes with large production capacities, ie up to 1000 tonnes / day and above. [Background technology]

[0003] Global warming and the requirement to reduce CO2 emissions are increasing pressure on glass manufacturers, and energy prices and CO2 taxes could soon pose a serious threat to competitiveness in the glass sector.

[0004] In conjunction with urgent measures to reduce carbon emissions, the glass industry has invested heavily over the years in decarbonising its manufacturing processes in order to produce glass products that are sustainable, resource-efficient and compatible with a low-carbon society.

[0005] To enable the transition, the glass sector has already identified a number of solutions / technologies to move closer to its ambitious target, such as the use of electricity as an energy source, the use of alternative and more environmentally friendly energy sources such as H2 or biogas, the use of alternative raw materials, the increased use of cullet as a raw material, heat recovery, Carbon Capture Utilisation and Storage (or CCUS), etc.

[0006] Nevertheless, all these techniques have serious drawbacks or problems for practical application or are not viable from an economic point of view. Therefore, there remains an urgent need for a glass melting process that can dramatically reduce the amount of CO2 emitted and is economically acceptable for glass manufacturers.

[0007] Regarding the use of electricity as an energy source, it is known that furnaces using electrical energy to melt the glass raw material not only show a reduction in CO2 emissions, but also a reduction in total energy consumption. In such a configuration, the melting furnace is immersed and includes an electrode, generally located at the bottom of the tank, through which the current / power is passed and the bath of molten glass is heated from its bulk. However, glass melting furnaces in which the heating power is entirely supplied by electricity are not utilized in flat glass technology when high quality glass is required, due to significant temperature and glass convection / flow problems.

[0008] Therefore, conventional glass melting furnaces for flat glass are generally only electrically "boosted" in a so-called "hybrid" configuration combining combustion heating means, i.e. burners, with electric heating means, i.e. submerged electrodes. In such known "electrically boosted combustion furnaces", the electrical input rate is limited to a maximum of 10-15% of the total energy input, which prevents the full utilization of the energy consumption advantages of electric melting.

[0009] Recently, a new furnace design described in EP 21200998.9, incorporated herein by reference, has made it possible to achieve significantly higher electrical input rates in "hybrid" furnaces, e.g., greater than about 50%.

[0010] Even though there are clear environmental / energy consumption / CO2-emission advantages associated with the use of alternative and environmentally friendly energy sources such as hydrogen H2 or biogas, serious constraints prevent their widespread use in the glass industry (lack of availability of biogas, high cost of hydrogen H2 which makes it an economically unviable solution as long as it is the only energy source for melting the glass raw materials).

[0011] Concerning heat recovery, waste heat recovery from exhaust gases is already widely applied in the glass industry to preheat the combustion air entering the furnace at temperatures above 1000°C or gas and oxygen ("Hotox") at temperatures above 400°C and 500°C, respectively. The waste heat of the exhaust gases can also be utilized to preheat the vitrifiable material, in particular the cullet. Nevertheless, it is known that in this case the temperature of the exhaust gases leaving the raw material is too low to combine the preheating of the raw material / cullet with electric melting.

[0012] Regarding the use of CO2 capture, generally, the CO2 capture process in industrial processes / plants consists of two steps: (i) separation of CO2 from the exhaust gas mixture by selective reaction with a separation material (CO2 "absorption"), and (ii) regeneration of the used material by a reverse reaction (CO2 "desorption"). The separation material can be reused for CO2 capture by sequentially repeating steps (i) and (ii). Amines in the form of solvents, membranes or porous adsorbents are the most widely used materials in CO2 capture processes industrially so far, due to the mature technology and the effective separation of amines and CO2 by reversible reactions. Nevertheless, such amine processes (e.g. those using aqueous MEA) remain a poor option, especially in the special context of the glass industry, for at least the following main reasons: - The combustion gases / exhaust gases from known glass manufacturing processes contain low concentrations of CO2 (typically less than 30% by volume, often around 10-20% by volume) and many other components (mainly N2, H2O, O2, NO x , S.O. x The presence of fluorine, etc., results in low purity, which significantly affects the efficiency of the CO2 capture process. - The amine-CO2 capture process requires a lot of energy to regenerate the amine sorbent (desorption process), thereby affecting the overall energy consumption (and depending on the energy source used may affect the CO2 emissions, obviously with adverse effects in this regard).

[0013] Furthermore, known glass manufacturing processes generate very high volumes or flow rates of exhaust gases, which also directly impacts the investment and operating costs when attempting to capture CO2 from the exhaust gases, whatever the method used. Summary of the Invention [Problem to be solved by the invention]

[0014] The object of the present invention is to overcome the above mentioned drawbacks with respect to the prior art and to solve the technical problems by providing a glass melting process for producing flat glass, which exhibits a reduced total energy consumption and reduced CO2 emissions compared to conventional melting furnaces.

[0015] It is a further object of the present invention to provide a glass melting process for producing flat glass that is economically viable and exhibits reduced overall energy consumption and reduced CO2 emissions compared to conventional melting furnaces.

[0016] It is a further object of the present invention to provide a glass melting process for producing flat glass that exhibits reduced overall energy consumption and reduced CO2 emissions compared to conventional melting furnaces, while allowing for simple and cost-effective CO2 capture. [Means for solving the problem]

[0017] The present invention relates to a process for producing glass sheets by melting a vitrifiable material, the process comprising the steps of: - providing a furnace comprising: (i) at least one melting tank including electric heating means; (ii) a refining tank equipped with oxy-fuel heating means; (iii) at least one neck separating the at least one melting tank and the refining tank; (iv) inlet means arranged in the at least one melting tank; and (v) outlet means arranged downstream of the refining tank; - charging vitrifiable material including raw materials and cullet into at least one melting tank by means of an inlet means, the amount of cullet being at least 10% by weight of the total amount of vitrifiable material; - melting the vitrifiable material in at least one melting tank by heating with electrical heating means, - refining the melt in a refining tank by heating with an oxy-combustion heating means supplied with gas and / or hydrogen, - flowing the melt from the refinery tank through an outlet means to a working zone; - capturing CO2 from a flue gas having a CO2 concentration of at least 35% wherein the electricity input rate is in the range of 50% to 85%, and the step of capturing CO2 from the flue gas includes a compression and / or dehydration step.

[0018] The present invention is therefore based on a new and original approach. In particular, the inventors have discovered that in a glass melting process for producing flat glass: - use of furnaces with a specific division design (separation of the electrically heated melting zone and the combustion heated refining zone); - the use of oxygen as a combustion promoter; - Use of gas and / or hydrogen as combustible substances; - the use of a minimum amount of cullet in the vitrifiable material; and - Use of specific power input rates By combining - A significant reduction in total energy expenditure, and - A significant reduction in total CO2 emissions, and - A significant reduction in flue gas volume and a significant increase in the CO2 concentration and purity in said flue gas It has been found that it is possible to simultaneously obtain both CO2 capture and CO2 capture efficiency, thereby enabling the use of a simple, efficient and cost-effective CO2 capture process.

[0019] By implementing all of the features of the present invention, the process of the present invention exhibits a very low CO2 fingerprint and is economically viable.

[0020] In the present specification and claims, the terms "a", "an" or "the" as used herein mean "at least one" and should not be limited to "only one", unless expressly indicated to the contrary, as will be well understood by those skilled in the art. When ranges are indicated, the ends are included. Furthermore, all integer values ​​and subdomain values ​​contained in numerical ranges are expressly included as if expressly recited. Finally, the terms "upstream" and "downstream" refer to the glass flow direction and are understood in their general sense, i.e., from the inlet means to the outlet means along the average direction of movement of the vitrifiable material / glass melt. The expression "upstream" is understood to mean the first upstream third of the length, said length being located along the horizontal longitudinal axis of the furnace. The expression "downstream" is understood to mean the last downstream third of said length.

[0021] Other characteristics and advantages of the invention will appear more clearly on reading the following description of preferred embodiments and figures, given by way of a simple illustrative and non-limiting example. [Brief description of the drawings]

[0022] [Figure 1] 1 is a flow chart of an embodiment of a process of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] According to the present invention, and as shown in FIG. 1 , a process for melting vitrifiable material to produce sheet glass comprises the steps of providing a furnace including: (i) at least one melting tank including electric heating means; (ii) a refining tank equipped with oxy-fuel heating means; (iii) at least one neck separating the at least one melting tank and the refining tank; (iv) inlet means disposed in the at least one melting tank; and (v) outlet means (for the flow of molten glass to a working zone) disposed downstream of the refining tank.

[0024] According to the present invention and as commonly employed in the glass technology field, "melting tank" means a tank defining a zone in which vitrifiable material (raw material and / or cullet) is charged and melted by heating, and which, when the furnace is in process, includes the melt and a "blanket" of unmelted vitrifiable material floating on the melt and gradually melting.

[0025] According to the present invention, and as commonly employed in the glass art, a "refining tank" means a tank defining a zone in which there is no longer a "blanket" of unmelted vitrifiable material floating on the melt, and in which the glass melt is heated to a temperature higher than the melting tank temperature (typically above 1400° C. or above 1450° C.) in order to purify the glass (mainly by removing the majority of the gas bubbles). This refining tank is also commonly called a "clarifying tank" in the art.

[0026] According to the invention, the "neck" separating the melting tank and the refining tank means that the width (or in the direction perpendicular to the direction of glass movement) of the melting tank is narrowed. The opening of the neck according to the invention can be completely below the glass melt / blanket free surface (in which case it is also commonly referred to in the art as "throat") or partially below the glass melt / blanket free surface (in which case it leaves a free opening above the glass). Preferably, the opening of the crown is partially below the glass melt free surface, which allows the presence of a backflow of surface glass from the refining tank towards the melting tank. This is advantageous, firstly, because it allows to stabilize the blanket of raw material and to avoid the flow of unmelted particles directly towards the refining tank, and secondly, because it allows to avoid the flow of potential defects occurring at the contact of glass, refractory and atmosphere directly into the refining tank. These aspects can advantageously improve the quality of the glass. Furthermore, the wider opening allows for a lower glass velocity and a reduced erosion and wear of the refractory. This aspect advantageously increases the life of the furnace.

[0027] This furnace design with separate melting tank and refining tank offers many advantages in terms of energy consumption / CO2 emissions and is favorable for the mechanical stability / lifetime of the furnace. Particularly advantageously, the present invention allows the furnace with this particular split design to treat the off-gases from the melting tank and the off-gases from the refining tank independently, if necessary.

[0028] The split glass furnace invention described in EP 21200998.9 and all its embodiments are incorporated herein by reference as embodiments of the present invention.

[0029] According to a particular embodiment, the furnace of the invention comprises: 0.1 * W2≦W3i≦0.6 * W2, W1i≧1.4 * W3i is defined by W1i is the width of at least one melt tank, W2 is the width of the purification tank, W3i is the width of at least one neck.

[0030] This last particular design is advantageous in finding a good compromise between two opposing requirements: from the one hand, (1) the neck between the melting zone and the refining zone should ideally be as narrow as possible, in order to reduce the opening between the melting superstructure / crown and the refining superstructure / crown and (2) to create an obstacle to the convection strength of the total glass melt in the melting tank, and from the other hand, the neck should ideally be as wide as possible, in order to limit the glass velocity inside the neck and to limit the wear / corrosion of the neck refractory wall.

[0031] According to the invention, the furnace may include one melting tank and one neck or two melting tanks and two necks or even three melting tanks and three necks. These specific design embodiments are extensively described in EP 21200998.9, which is incorporated herein by reference.

[0032] For example, in a "two melting tank" configuration, the furnace: (i) a first melting tank; (ii) a second melting tank; (iii) Refinery tanks; (iv) a neck separating the first melting tank and the refining tank, (v) a neck Nii separating the second melting tank and the refining tank; (vi) at least one inlet means disposed in the first melting tank; (vii) at least one inlet means disposed in the second melting tank; (viii) at least one outlet means disposed in the purification tank; may include.

[0033] According to this particular embodiment, the furnace advantageously comprises: 0.1 *W2≦W3i≦0.6 * W2, 0.1 * W2≦W3ii≦0.6 * W2, W1i≧1.4 * W3i, W1ii≧1.4 * W3ii

[0046] W1i is the width of the first melt tank, W1ii is the width of the second melt tank, W2 is the width of the purification tank, W3i is the width of the neck Ni, W3ii is the width of the neck Nii.

[0034] Preferably, the total surface area of ​​the melting tank is between 25 and 400 m 2 Also preferably, according to the invention, the surface area of ​​the purification tank is between 25 and 400 m 2 It is.

[0035] In accordance with the present invention, and as shown in FIG. 1, a process for melting vitrifiable material to produce sheet glass includes charging vitrifiable material, including raw materials and cullet, into at least one melting tank using an inlet means.

[0036] According to the present invention, since the vitrifiable material comprises raw material and cullet, preferably both are charged together into at least one melting tank, i.e. through the same inlet means. Alternatively, both are charged independently into at least one melting tank through different inlet means (e.g. one inlet means for raw material and one inlet means for cullet or two inlet means for raw material and two inlet means for cullet).

[0037] According to the invention, the amount of cullet is at least 10% by weight of the total amount of vitrifiable material. Preferably, the amount of cullet is at least 20% by weight of the total amount of vitrifiable material. More preferably, the amount of cullet is at least 30% by weight, and even more preferably at least 40% by weight of the total amount of vitrifiable material. This is advantageous because it allows to reduce the CO2 generation / emissions of the process of the invention (due to the reduction of the emissions resulting from the decarbonation of the carbonate raw material). Preferably, the amount of cullet is at most 90% by weight or at most 80% by weight of the total amount of vitrifiable material. More preferably, the amount of cullet is at most 70% by weight or even at most 60% by weight of the total amount of vitrifiable material.

[0038] Preferably, and as known in the art, the inlet means is located upstream of the at least one melt tank (transverse to the width of said tank or its length) or at the top of the at least one melt tank (a "top batch charger").

[0039] In an advantageous embodiment of the invention, the furnace comprises at least one melting tank which is laterally expanded and equipped with at least two inlet means which are arranged on both sides of the melting tank, on the lateral sides or as a top batch charger depending on the position of the neck.

[0040] According to the present invention and as shown in FIG. 1, a process for melting vitrifiable material to produce glass sheets comprises melting the vitrifiable material in at least one melting tank by heating with electrical heating means.

[0041] The electric heating means according to the invention preferably consists of electrodes arranged at the bottom of at least one melting tank, preferably immersed. The electrodes are advantageously arranged in a grid (checkerboard) of multiples of 3 or 2 to facilitate connection to the transformer and current balancing. For example, a maximum current density of 1.5 A / cm2 on the electrode surface is achieved. 2By complying with the above, the number of electrodes is designed to limit the maximum power of each electrode to 200 kW. For example, the height of the immersed electrodes is also 0.3-0.8 times the height of the glass melt.

[0042] According to the present invention, the electricity input rate is in the range of 50%-85%. "Electricity input rate" according to the present invention means the portion of electricity in the total energy input of the process / furnace for melting / refining, i.e. electricity / (fuel+electricity), where the total energy input is that of the process / furnace in standard / normal production mode, i.e. in its standard pull range (excluding periods of start-up, maintenance, hot repairs, cullet production, etc.).

[0043] According to the present invention and as shown in Figure 1, the process of melting vitrifiable material to produce glass sheets comprises purifying the melt in a refining tank by heating with an oxy-fuel heating means supplied with gas and / or hydrogen. As used herein, the term "gas" includes, but is not limited to, natural gas, synthetic gas and biogas. Natural gas is currently the most widely used due to its practicality, economy and availability.

[0044] By "oxygen combustion means" according to the present invention is meant a combustion means supplied with gaseous oxygen (O2) as a combustion support. Typically, the O2 gaseous combustion support supplied to the glass melting furnace is at least 90% pure or at least 95% pure. The advantage of using gaseous oxygen as a combustion support is that, compared to the use of air, the so-called corrosive "NOx" pollutants generated during combustion are significantly reduced. Even if they are present in the exhaust gas (depending on the O2 purity and the amount of parasitic air), their amount is very small.

[0045] The oxy-combustion heating means according to the invention may consist of burners advantageously arranged along the side walls of the tank on both sides thereof in order to spread the flame over substantially the entire width of said tank. The burners may be spaced apart from one another in order to distribute the energy supply over a portion of the refinery tank (i.e. about 50% of the length). It is also common for them to be arranged in a row on both sides of the tank.

[0046] According to the invention, the oxy-combustion heating means is supplied with gas and / or hydrogen. In one embodiment, the oxy-combustion heating means is supplied with at least 50% hydrogen, preferably at least 80% hydrogen. More preferably, the oxy-combustion heating means is supplied with 100% hydrogen. This is advantageous since it allows to dramatically reduce the total CO2 emissions of the process. Alternatively, the oxy-combustion heating means is supplied with more than 50%, preferably at least 80%, or even at least 100% gas. This is advantageous since it allows to reach higher CO2 concentrations in the exhaust gas, which not only facilitates and improves the CO2 capture step, but also reduces the impact on the glass chemistry and the furnace refractories. In a specific and advantageous embodiment of the invention, the oxy-combustion heating means is supplied with 50% gas and 50% hydrogen.

[0047] According to the present invention, and as shown in FIG. 1, a process for melting vitrifiable material to produce glass sheets includes flowing the melt from a refining tank through an outlet means to a working zone.

[0048] According to the invention, the outlet means is arranged downstream of the refining tank so that the molten glass reaches the working zone. According to one embodiment, the outlet means usually consists of a neck to direct the melt towards the working zone, commonly called the "working end". Alternatively, the outlet means consists of a throat to direct the melt into the working zone, which for example includes a fore-bed. The working zone according to the invention may for example include a conditioning zone, in which thermal conditioning by controlled cooling is performed before the glass melt leaves the forming zone through the outlet. Such a forming zone may for example include a float installation and / or a rolling installation.

[0049] According to the present invention and as shown in FIG. 1, the process of melting vitrifiable material to produce flat glass includes capturing CO2 from the exhaust gases.

[0050] According to the invention, the flue gas (i.e. the flue gas that has undergone the CO2 capture step) has a CO2 concentration of at least 35%. The CO2 concentration according to the invention is defined for dry flue gas, i.e. flue gas containing all components except water (H2O). Preferably, the flue gas in the present invention has a CO2 concentration of at least 40%, more preferably at least 50%, even more preferably at least 60%. This is advantageous, since the higher the CO2 concentration of the flue gas, the easier and more effective the CO2 capture applied to this flue gas.

[0051] According to the invention and as shown in Figure 1, the step of capturing CO2 from the flue gas comprises a compression and / or dehydration step. The dehydration step corresponds to a step of compressing and / or drying the water in the flue gas. The compression step generally corresponds to increasing the pressure of the CO2 by using a compressor. The dehydration step may precede the compression step and / or the dehydration step may be concomitant to the compression step.

[0052] In particular, the step of capturing CO2 from the exhaust gas according to the present invention may be carried out in a known manner using a CO2 compression purification unit (or CPU).

[0053] As shown in Figure 1, exhaust gas according to the invention can be recovered from at least one melting tank or refinery tank or both for CO2 capture. In particular, when only hydrogen is supplied to the oxyfuel heating means according to the invention, exhaust gas is advantageously recovered only from the at least one melting tank (exhaust gas originating from the refinery tank does not contain CO2).

[0054] After the CO2 capture step according to the invention, the CO2 product may for example have a pressure of about 35 bar at a temperature between 5°C and 40°C in gas form, suitable for transport through a pipeline, or a pressure of about 100 bar in liquid form, suitable for transport through a pipeline, but also suitable for transport by truck or rail. It is also known that 15 barg at -35°C is suitable for transport by truck.

[0055] This simple and effective CO2 capture process is highly advantageous as it can avoid the use of any adsorbents / chemical reagents that contribute to operational / energy costs and environmental issues, allowing for cost-effective CO2 capture to be achieved, making the entire process of the present invention economically viable.

[0056] According to a preferred embodiment, the step of capturing CO2 from the flue gas essentially comprises a compression and / or dehydration step.

[0057] According to an advantageous embodiment, the process of the invention further comprises a step of removing acidic components from the exhaust gas, said step of removing acidic components being carried out before or simultaneously with the step of capturing CO2 (for example before or simultaneously / together with the compression and / or dehydration steps).

[0058] The step of removing acidic components may include desulfurizing the exhaust gas (or removing so-called "SOx" compounds). It may also include removing so-called "NOx" compounds that may be present in very small amounts due to the use of oxygen as a combustion support. This is advantageous as it allows the removal of corrosive compounds (SOx, NOx) before transport, storage and / or utilization.

[0059] After the CO2 capture step according to the invention, in a known manner, the CO2 product (e.g. in liquid form) can be transported through a pipeline to a final destination and then stored / sequestrated (e.g. in a geological formation such as a deep seabed or saline aquifer) or utilized (e.g. for enhanced oil recovery, food / beverage applications or fire protection applications). Advantageously, the CO2 product obtained after the CO2 capture step can be used locally to limit transportation. This can be considered if the amount of captured CO2 is not too high so that it can be absorbed in the local market.

[0060] According to an advantageous embodiment of the invention, the process further comprises a cullet preheating step, prior to charging the cullet into at least one melting tank, at least partially by recovering heat from a furnace. According to this embodiment, the heat recovery from the furnace can be carried out from the exhaust gases leaving (i) the melting tank, or (ii) the refining tank, or (iii) the entire furnace (thereby including the exhaust gases from the melting tank and the refining tank).

[0061] According to this embodiment, advantageously, a CO2 capture step can be performed from the exhaust gases used in the cullet pre-heating step.

[0062] According to this embodiment, the raw materials are charged into at least one melting tank together with the preheated cullet through the same inlet means (which therefore means that both types of vitrifiable material are mixed before charging). Instead, the raw materials are charged into at least one melting tank through different inlet means, independently of the preheated cullet.

[0063] Preferably, according to this embodiment, the maximum temperature of the cullet in the cullet preheating step is 450° C. This can avoid clogging problems.

[0064] According to an embodiment, the cullet preheating step can be carried out in at least one cullet preheater of the type of one of those described, for example, in U.S. Pat. No. 5,526,580 or DE 3,716,687.

[0065] Advantageously, at least one cullet preheater may be arranged in the upstream part of at least one melting tank either in the width or in the transverse direction of said tank. Advantageously, the cullet preheating step may be carried out, for example, with at least two cullet preheaters arranged in the upstream part of at least one melting tank on both sides in the transverse direction of its width or length. For example, the cullet preheating step may be carried out with four cullet preheaters arranged in the upstream part of at least one melting tank distributed in the transverse direction of its width or length (for example, two on each side). For example, the cullet preheating step may also be carried out with six cullet preheaters arranged in the upstream part of at least one melting tank in the transverse direction of its width or its length (for example, three on each side) or eight cullet preheaters arranged in the upstream part of at least one melting tank in the transverse direction of its width or its length (for example, four on each side).

[0066] According to another advantageous embodiment of the invention, the process further comprises a step of premelting at least a part of the cullet in an auxiliary melting tank and flowing the premelted cullet into at least one melting tank (hereinafter referred to as the "main melting tank"). According to this embodiment, a part of the cullet that is premelted is charged into the auxiliary melting tank, and the remaining part of the cullet (not premelted), if any, is charged into at least one main melting tank. This embodiment has the advantage of preventing a shortage of good quality cullet, since it allows the use of lower quality or contaminated cullet in the process of the invention. In fact, in this embodiment, at least a part of the cullet is "slaked" beforehand in the auxiliary melting tank. For example, metal compounds present in the cullet can be removed in this auxiliary melting tank by using a reducing agent (such as coke or anthracite) to produce a molten metal that is separated from the glass melt by decanting at the bottom of the auxiliary melting tank, while the resulting "purified" glass melt can flow from the top towards the main melting tank.

[0067] According to this embodiment, the auxiliary melting tank is preferably connected upstream of the at least one main melting tank, more preferably as far upstream as possible of the at least one main melting tank.

[0068] Also, according to this embodiment of the invention, only a portion of the cullet is premelted in the auxiliary melting tank. For example, a portion of the cullet that is considered "contaminated" or not clean enough is premelted in the auxiliary melting tank, and the remaining "clean" portion of the cullet is loaded into at least one main melting tank. Instead, the entire amount of cullet is premelted in the auxiliary melting tank.

[0069] Further in accordance with this embodiment of the invention, the process preferably includes the step of pre-heating at least a portion of the cullet prior to charging into the auxiliary melting tank, at least in part by recovering heat from a furnace.

[0070] An example of an auxiliary melter tank suitable for this embodiment is described in EP 2 137 115 A1.

[0071] According to another advantageous embodiment of the invention, the raw material comprises less than 25% by weight of carbonate compounds. By "carbonate compounds" is meant, for example, alkali and alkaline earth carbonates. Preferably, the raw material comprises less than 20% by weight of carbonate compounds, more preferably less than 10% by weight, even more preferably less than 5% by weight. The raw material may advantageously be free of any carbonate compounds.

[0072] This embodiment is advantageous since it makes it possible to reduce part of the CO2 emissions resulting from the decarbonation of the raw materials, compared to conventional glass melting processes, in which sodium carbonate Na2CO3, limestone CaCO3 and dolomite CaMg(CO3)2 are generally and essentially used as sources of sodium and calcium. According to this embodiment, the alkali and alkaline earth sources may advantageously be present at least partially in the form of oxides or hydroxides, such as CaO, CaO·MgO (dolim), Ca(OH)2, Mg(OH)2, NaOH, KOH.

[0073] According to a highly preferred embodiment of the present invention, the process for melting vitrifiable material to produce glass sheets comprises the steps of: - providing a furnace comprising: (i) at least one main melting tank including electric heating means; (ii) an auxiliary melting tank; (iii) a refinery tank equipped with oxygen-fired heating means; (iv) at least one neck separating the at least one main melting tank and the refinery tank; (v) inlet means arranged in the at least one main melting tank; and (vi) outlet means arranged downstream of the refinery tank; - charging vitrifiable material into at least one main melting tank and / or into an auxiliary melting tank using an inlet means, said vitrifiable material comprising (i) raw material having less than 25% by weight of carbonate compounds, and (ii) cullet in an amount of at least 10% by weight of the total amount of vitrifiable material; - a step of pre-heating the cullet by at least partially recovering heat from a furnace before charging the cullet into at least one main and / or auxiliary melting tank; - premelting at least a portion of the cullet in an auxiliary melting tank and flowing the premelted cullet into at least one main melting tank; - melting the vitrifiable material in at least one main melting tank by heating with an electric heating means, the electric input rate in the process being 50%-85%; - refining the melt in a refining tank by heating with an oxy-combustion heating means supplied with gas and / or hydrogen, - flowing the melt from the refinery tank through an outlet means to a working zone; - capturing CO2 from flue gas having a CO2 concentration higher than 35%, comprising a compression and / or dehydration step; Includes.

[0074] All of the specific embodiments described above relating to each step of the process of the present invention apply to this last highly preferred embodiment.

[0075] Those skilled in the art will understand that the present invention is in no way limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. It should be further noted that the present invention relates to all possible combinations of the features and preferred features described in this specification and claimed in the following claims.

[0076] The following examples are provided for illustrative purposes and are not intended to limit the scope of the present invention. EXAMPLES

[0077] Considering the same glass pull rate (750 tonnes / day) and the same cullet amount (40% by weight), the following process example was calculated taking into account the following furnace designs: - Example 1 (comparison): conventional fired glass melting furnace with one tank containing the melting and refining zones, with burners supplied with air / natural gas (NG) (fully combusted energy). - Example 2 (comparison): Conventional fired glass melting furnace with one tank containing the melting and refining zones, with burners supplied with O2 / natural gas (NG) (fully combusted energy). - Example 3 (comparison): conventional fired glass melting furnace with one tank containing melting and refining zones, equipped with burners fed with O2 / H2 (fully combusted energy). - Example 4 (comparison): Conventional fired glass melting furnace (fully fired energy) with one tank including melting and purification zones, with burners fed with air / natural gas (NG) and electrodes for electric boosting. The power of the electric boosting was set at 5 MW. - Example 5 (comparison): Conventional fired glass melting furnace (fully fired energy) with one tank including melting and purification zones, with burners fed with O2 / natural gas (NG) and electrodes for electric boosting. The power of the electric boosting was set at 5 MW. - Example 6 (comparison): Conventional fired glass melting furnace with one tank including melting and refining zones, with burners fed with O2 / H2 and electrodes for electric boosting (fully fired energy). The power of the electric boosting was set at 5 MW. Example 7 (invention): a melting tank containing electrodes, a purification tank equipped with burners supplied with O2 / natural gas (NG) and a split furnace equipped with a neck separating the melting tank and the purification tank. The power of the melting tank was set at 16 MW. Example 8 (invention): melting tank containing electrodes, refining tank equipped with burners supplied with O2 / H2 and a split furnace equipped with a neck separating the melting tank and the refining tank. The power of the melting tank was set at 16 MW. Example 9 (invention): melting tank containing electrodes, purification tank equipped with burners supplied with O2 / Natural Gas (NG):H2 50:50 and a split furnace equipped with a neck separating the melting tank and the purification tank. The power of the melting tank was set at 16 MW. Example 10 (invention): A melting tank containing electrodes, a purification tank equipped with burners supplied with O2 / natural gas (NG) and a split furnace equipped with a neck separating the melting tank and the purification tank. The power of the melting tank was set at 21 MW. Example 11 (invention): melting tank containing electrodes, refining tank equipped with burners supplied with O2 / H2 and a split furnace equipped with a neck separating the melting tank and the refining tank. The power of the melting tank was set at 21 MW. Example 12 (invention): melting tank containing electrodes, purification tank equipped with burners fed with O2 / Natural Gas (NG):H2 50:50 and a split furnace equipped with a neck separating the melting tank and the purification tank. The power of the melting tank was set at 21 MW.

[0078] Table 1a shows information regarding "Energy". Table 1b shows information regarding "Exhaust Gas" and "CO2 Capture Step". TIFF2024542673000002.tif121170

[0079] Regarding "Energy", Table 1a shows the combustible materials, fuels, power and total power used in the calculations, as well as the electrical input rate (power / total energy). TIFF2024542673000003.tif134170

[0080] Regarding "exhaust gas", Table 1b: - The exhaust gases extracted to undergo a CO2 capture step: exhaust gases from the entire furnace ("total" exhaust gases extracted from the melting tank and the refining tank) or exhaust gases from the melting tank only (in the case of a split furnace using 100% H2 as fuel, the exhaust gases from the refining tank do not contain CO2), - flow rate of flue gas (wet) undergoing the CO2 capture step, - CO2 concentration (defined for dry flue gas excluding H2O), - H2O concentration Shows.

[0081] Regarding "CO2 capture", Table 1b shows processes where an amine adsorption-desorption step and / or a dehydration / compression step are required (marked with an "x").

[0082] Table 1b also shows the total amount (in tonnes) of CO2 generated per year (taking into account the defined glass pull).

[0083] Tables 1a and 1b very clearly show that the process of the present invention (Examples 7-12) exhibits many advantages over the conventional furnaces (Examples 1-6) without the special design of the present invention: - Low total energy consumption (especially below 30MW), - Higher CO2 concentrations in the treated flue gas (especially >35%), which allows to avoid any expensive and energy-consuming adsorption-desorption steps (e.g. using amines) and use essentially simple dehydration / compression steps; - A smaller volume (or flow rate) of flue gas is treated by CO2 capture, which reduces operational costs and / or investments; - Lower H2O concentration in the flue gas treated by CO2 capture (specifically below 50%), which also reduces the operating costs of the dehydration step; - Less CO2 produced per year.

[0084] Regarding the amount of CO2 generated per year in the examples according to the invention (Examples 7 to 12), low values ​​(less than 60,000 tonnes / year, in particular less than 40,000 tonnes / year) are reached, which allows the captured CO2 to be more easily stabilized on-site, thereby limiting transportation (for use or long-distance sequestration) which would lead to significant additional costs (e.g. the transportation itself by truck or investments in pipeline equipment).

[0085] In contrast, Comparative Examples 1 to 6 show very low CO2 concentrations in the flue gas (thus making amine recovery necessary), and / or high total energy consumption (especially close to or above 40 MW), and / or high volumes of flue gas treated by CO2 capture, and / or high H2O concentrations in the flue gas treated by CO2 capture (especially above 50%), and / or high amounts of CO2 generated per year (especially close to or above 100,000 tonnes).

Claims

1. 1. A process for producing glass sheets by melting vitrifiable material, comprising: - providing a furnace comprising: (i) at least one melting tank including electric heating means; (ii) a refining tank equipped with oxygen-fuel combustion heating means; (iii) at least one neck separating said at least one melting tank from said refining tank; (iv) inlet means arranged in said at least one melting tank; and (v) outlet means arranged downstream of said refining tank; - charging said vitrifiable material, including raw materials and cullet, into said at least one melting tank using said inlet means, wherein the amount of said cullet is at least 10% by weight of the total amount of vitrifiable material; - melting said vitrifiable material in said at least one melting tank by heating with said electric heating means, - refining the melt in the refining tank by heating with the oxyfuel heating means supplied with gas and / or hydrogen, - allowing said melt to flow from said refining tank through said outlet means into a working zone; - at least 35% CO ２ CO from exhaust gas having a concentration ２ Step of capturing In a process including - its power input rate is in the range of 50% to 85%; - CO from the exhaust gas ２ The step of capturing the water may include a compression and / or dewatering step. A process characterized by

2. 2. The process for producing flat glass by melting vitrifiable material according to claim 1, wherein the amount of cullet is at least 30% by weight of the total amount of vitrifiable material.

3. 3. The process for melting vitrifiable material to produce glass sheets according to claim 1 or 2, characterized in that the oxyfuel heating means is supplied with at least 50% hydrogen, preferably at least 80% hydrogen.

4. The exhaust gas contains at least 40% CO ２ 3. A process for producing flat glass by melting the vitrifiable material according to claim 1 or 2, characterized in that it has a concentration.

5. The exhaust gas is at least 50% CO ２ 5. A process for producing flat glass by melting a vitrifiable material according to claim 4, characterized in that it has a concentration.

6. CO ２ 3. The process for producing glass sheets by melting vitrifiable material according to claim 1 or 2, characterized in that the step of capturing consists essentially of a compression and / or dehydration step.

7. 3. The process for melting vitrifiable material to produce flat glass according to claim 1 or 2, characterized in that the process further comprises the step of removing acidic components from the exhaust gas.

8. The step of removing acidic components from the exhaust gas comprises ２ 8. The process for melting vitrifiable material to produce glass sheets according to claim 7, characterized in that the step of capturing the

9. 3. The process for melting vitrifiable material to produce flat glass according to claim 1 or 2, characterized in that the process further comprises a step of preheating the cullet by at least partially recovering heat from the furnace before charging the cullet into the at least one melting tank.

10. 10. The process for producing flat glass by melting vitrifiable material according to claim 9, wherein the maximum temperature of the cullet in the cullet preheating step is 450°C.

11. 3. The process for melting vitrifiable material to produce sheet glass according to claim 1 or 2, characterized in that the process further comprises the steps of pre-melting at least a portion of the cullet in an auxiliary melting tank and flowing the pre-melted cullet into the at least one melting tank.

12. 3. The process for producing flat glass by melting vitrifiable material according to claim 1 or 2, characterized in that the raw materials contain less than 25% by weight of carbonate compounds.

13. A furnace for carrying out the process according to claim 1 or 2.

Images