Glass melting method with extremely low or zero CO2 emissions

Abstract

The present invention is a method for melting a vitrifiable material for producing sheet glass, comprising: (i) providing a furnace having a special divided design; (ii) charging a vitrifiable material containing raw materials and cullets into a melting tank using inlet means, provided that the amount of cullets is at least 10% by weight of the total amount of the vitrifiable material, and the raw materials contain less than 25% by weight of carbonate compounds; (iii) melting the vitrifiable material in the melting tank; (iv) purifying the melt in a purification tank by heating with oxygen combustion heating means supplied with gas and / or hydrogen; (v) flowing the melt from the purification tank to a working zone through outlet means; (vi) capturing CO2 from exhaust gas having a CO2 concentration of at least 35%, wherein the electricity input rate is 30% to 85%, and capturing CO2 includes compressing and / or dehydrating. The present invention relates to a method.

Description

Technical Field

[0001] The present invention relates to a glass melting method for continuously supplying molten glass to plate glass forming equipment such as float or rolling equipment. In particular, the present invention relates to a glass melting method that offers many advantages, particularly in terms of CO2, especially its emission and capture.

[0002] More particularly, the present invention relates to a method for melting plate glass, although not limited thereto, with a large production capacity, i.e., up to 1000 tons per day or more.

Background Art

[0003] The demands for global warming and CO2 emission reduction are increasing the pressure on glass manufacturers, and energy prices and CO2 taxes can immediately pose a serious threat to competitiveness in the glass sector.

[0004] The glass industry has been investing heavily in the decarbonization of manufacturing methods for many years to produce glass products that are sustainable, resource-efficient, and compatible with a low-carbon society in the context of urgent measures to reduce carbon emissions.

[0005] To enable the transition, the glass sector has already identified many solutions / technologies to approach its ambitious goals, 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, an increased use of cullet as a raw material, heat recovery, carbon dioxide capture, utilization, and storage (or CCUS), etc.

[0006] Nevertheless, all these technologies are associated with serious drawbacks or problems for practical implementation or are infeasible from an economic perspective. Therefore, there is still an urgent need for a glass melting method that can dramatically reduce the amount of CO2 emitted and is economically acceptable to glass manufacturers.

[0007] Regarding the use of electricity as an energy source:

[0008] Furnaces that use electrical energy to melt glass raw materials are known not only to show a reduction in CO2 emissions but also to show a reduction in total energy consumption. Although demonstrated only for small capacities, i.e., less than 300 tons per day (scaling up above 600 tons per day is still under development), glass melting furnaces are known and being developed in which all the heating power is supplied electrically.

[0009] In contrast to classical combustion furnaces called "hot top furnaces" (or "warm top furnaces"), these furnaces are also called "cold top furnaces". This is because the raw materials are dispersed on the glass melting surface, forming an insulating batch "blanket", so that the temperature above the blanket drops from about 1400 °C of the glass melt to less than 500 °C (optionally down to 50 °C). All-electric furnaces have significant advantages. First, they have very low direct emissions of CO2, thermal NO x , SO x .

[0010] Furthermore, since the melting energy is basically transmitted into the glass (for example, for electrodes that pass an electric current to heat the molten glass bath from its bulk), the heat loss of all-electric furnaces is much lower compared to hot top combustion furnaces where significant heat loss occurs from the upper furnace structure and in the residual exhaust gases, even when using a heat recovery system, thus making them highly energy-efficient furnaces. Unfortunately, all-electric furnaces also have some disadvantages compared to combustion hot top furnaces.

[0011] In particular, such furnaces - The quality of the glass does not reach the specifications of common sheet glass, especially with regard to the small bubble density. - The temperature at the bottom where the electrodes are placed is very high (e.g., > 1400 °C), which promotes the corrosion of the bottom refractories and the walls of the glass tank, significantly shortening the furnace life (typically from over 15 years for conventional furnaces to less than 8 years, optionally down to 2 - 7 years).

[0012] Furthermore, the surface melting rate of the cold-top all-electric furnace, i.e., the amount of glass melted from the raw materials per unit time and per unit furnace area (T / d / m 2 displayed) is a direct function of the glass temperature. To achieve an acceptable surface melting rate (about 2 - 3 T / d / m 2 ) in such a furnace, a glass temperature of 1400 °C or higher, or 1450 °C or higher, needs to be targeted, which further negatively affects the furnace life. For comparison, the surface melting rate of a classical combustion furnace is typically about 5 T / d / m 2 . Instead, setting a low surface melting rate to avoid affecting the furnace life as much as possible means significantly increasing the melting area, which consequently has a great negative impact on the required investment and industrial floor area.

[0013] Finally, such cold-top furnaces have no flexibility in terms of energy (only electricity).

[0014] It is also known to combine combustion heating means and electric heating means in a "hybrid system". In such a configuration, which mainly operates with a "hot top", the furnace is composed of burners and electrodes for power supply.

[0015] Such hybrid furnaces have great advantages in terms of energy flexibility and can adapt the electric input rate to various parameters in operation or assumptions.

[0016] Furthermore, compared with cold-top furnaces, if the bottom temperature is the same, the hot-top furnace can reach a higher surface melting rate (or if the surface melting rate is the same, it can reach a lower bottom temperature).

[0017] Next, the hybrid furnace operated with a "warm top" has several drawbacks. In particular, (i) significant heat losses occur in the crown and walls of the melting zone, and (ii) in the high-temperature exhaust gas / exhaust gas generated during melting, thereby reducing the energy efficiency of the furnace. Although a heat recovery system can be considered to suppress the heat lost by the exhaust gas, this problem cannot be solved and special investment is required.

[0018] Furthermore, in such a furnace, the temperature of the crown / upper structure in the melting zone becomes very low depending on the conditions (e.g., less than 1000 °C), and the risk of alkali condensation (e.g., NaOH) in said zone, and thus corrosion of the crown refractory, increases significantly.

[0019] Next, in these furnaces, especially for all-electric furnaces, due to the above-mentioned limitations, i.e., the corrosion phenomena at the bottom and the crown, the electric input rate is generally limited to a maximum of 35% of the total energy input.

[0020] Recently, some hybrid furnaces with special designs to increase the electric input rate up to, for example, 80% have been described, but most of them are operated in cold top furnaces, which bring problems.

[0021] Regarding the use of alternative and environmentally friendly energy sources such as hydrogen H2 or biogas: Although it is clear that there are advantages in terms of environment / energy consumption / CO2 emissions, due to serious constraints (lack of availability of biogas, high cost of hydrogen H2 which is an economically unfeasible solution as long as it is the only energy source for melting glass raw materials), wide use in the glass industry is inhibited.

[0022] Regarding heat recovery:

[0023] Waste heat recovery from exhaust gases is already widely applied in the glass industry to preheat combustion air entering the furnace at temperatures above 1000 °C or gas and oxygen (「Hotox」) at temperatures above 400 °C and 500 °C, respectively. It is also possible to utilize the waste heat of the exhaust gases to preheat vitrifiable materials, especially cullet. Nevertheless, in this case, it is known that the temperature of the exhaust gases discharged from the raw materials is too low, so that the preheating of the raw materials / cullet cannot be combined with electric melting.

[0024] Regarding the use of CO2 capture:

[0025] Generally, the CO2 capture method in industrial processes / plants consists of two steps: (i) separation of CO2 from the exhaust gas mixture by selective reaction with a separation material (「absorption」 of CO2), (ii) regeneration of the used material by a reverse reaction (「desorption」 of CO2). 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 industrial CO2 capture methods so far because the technology is mature and effective separation of amines and CO2 by reversible reactions is possible. Nevertheless, such amine methods (e.g., those using aqueous MEA) remain poor options, especially in the special circumstances of the glass industry, for at least the following main reasons: - The combustion gases / exhaust gases in known glass manufacturing methods have a low CO2 concentration (generally less than 30 vol%, often around 10 - 20 vol%) and low purity due to the presence of many other components (mainly N2, H2O, O2, NO x , SO x etc.), which greatly affects the efficiency of the CO2 capture method. - The amine - CO2 capture method requires a lot of energy to regenerate the amine adsorbent (desorption method), which affects the total energy consumption (and can affect the CO2 emissions depending on the energy source used, clearly having a reverse effect in this regard).

[0026] Furthermore, known glass manufacturing methods generate very high volumes or flows of exhaust gases. This also directly affects the investment and operating costs when attempting to capture CO2 from the exhaust gases, regardless of the method used. Summary of the Invention Problems to be Solved by the Invention

[0027] The object of the present invention is to overcome the above-mentioned drawbacks with respect to the prior art and solve the technical problems by providing a glass melting method for manufacturing sheet glass using combustion and electric heating means, which shows a reduction in total energy consumption and a reduction in CO2 emissions compared to conventional melting furnaces, particularly conventional "hot top" hybrid furnaces.

[0028] A further object of the present invention is to provide a glass melting method for manufacturing sheet glass using combustion and electric heating means, which exhibits an acceptable surface melting rate (particularly greater than 2 T / d / m 2 or more preferably greater than 3 T / d / m 2 of the surface melting rate).

[0029] A further object of the present invention is to provide a glass melting method for manufacturing sheet glass using combustion and electric heating means, which provides a sheet glass with an improved lifespan compared to classical hot top hybrid melting furnaces.

[0030] A further object of the present invention is to provide a glass melting method for manufacturing sheet glass using combustion and electric heating means, which enables simple and cost-effective CO2 capture.

[0031] A further object of the present invention is to provide a glass melting method for manufacturing sheet glass using combustion and electric heating means, which is economically viable. Means for Solving the Problems

[0032] The present invention relates to a method for melting vitrifiable material for producing glass sheets, the method comprising: (i) a melting tank M comprising at least one upstream zone Z1 covered by a crown C1 and equipped with electrical heating means, a downstream zone Z2 covered by a crown C2 and equipped with combustion heating means 3 and a transition zone T between the crowns C1 and C2, (ii) a refining tank F, covered with crown C4 and equipped with an oxygen combustion heating means; (iii) a neck N, covered by a crown C3, separating the melting tank M from the refining tank F; (iv) at least one inlet means X disposed in the melting tank M; (v) an outlet means O disposed downstream of the purification tank F; and (vi) at least one exhaust gas extraction means arranged in at least one upstream zone Z1

[0023] providing a furnace comprising: However, the furnace has a H1≦0.75 * The height H1 of the crown C1 defined by H2 (where H2 is the height of the crown C2) is 0.25 * (L1+L2)≦L1≦0.8 * At least one upstream zone Z1 has a length L1 defined by (L1+L2) (where L2 is the length of the downstream zone Z2) and LT≦0.2 * The transition zone T has a length LT defined by (L1+L2), - charging vitrifiable materials, including raw materials and cullet, into the melting tank M by means of at least one inlet means X, whereby the amount of cullet is at least 10% by weight of the total amount of vitrifiable materials, and the raw materials contain less than 25% by weight of carbonate compounds; - melting the vitrifiable material in a melting tank M by means of heating means; - refining the melt in a refining tank F by heating using oxy-combustion heating means supplied with gas and / or hydrogen; - flowing the melt from the purification tank F through outlet means O into the working zone; - Capturing CO2 from exhaust gas having a CO2 concentration of at least 35% However, the air input rate is 30% - 85%, and capturing CO2 from the exhaust gas includes compressing and / or dehydrating.

[0033] Therefore, the present invention is based on a novel and innovative approach. In particular, the inventors have, in a glass melting method for manufacturing sheet glass, - using a specially designed furnace including a combination of (i) separating a "hybrid" melting tank and a combustion purification zone by a neck, and (ii) dividing the melting tank into two zones having different crown heights (thereby providing a cooler upstream zone and a hotter downstream zone with a significant temperature difference), - using oxygen as a combustion agent, - using gas and / or hydrogen as combustible substances, - using a minimum amount of cullet in the vitrifiable material, - using a minimum amount of decarbonation raw material in the vitrifiable material, and - using a specific high electrical input rate By combining,[[]] - an acceptable surface melting rate, - an extended furnace life, - a significant reduction in total energy consumption, - a significant reduction in the total amount of CO2 generated, - being able to independently extract the exhaust gas resulting from raw material decomposition (poor in NOx and SOx impurities) and the exhaust gas resulting from combustion, and thereby, if necessary, separating and appropriately treating each of them, - a significant reduction in the exhaust gas volume and a significant increase in the CO2 concentration and its purity in the exhaust gas It has been found that it is possible to simultaneously obtain, thereby enabling the use of a simple, efficient and cost-effective CO2 capture method.

[0034] By implementing all the features of the present invention, the method of the present invention exhibits a very low CO2 fingerprint and is economically feasible.

[0035] In this specification and the claims, it is well understood by those skilled in the art that the terms "a", "an", or "the" as used herein mean "at least one" and should not be limited to "only one" unless the contrary is explicitly stated. When a range is indicated, the endpoints are included. Further, all integer values and subdomain values included in a numerical range are explicitly included as if they were explicitly recited. Finally, the terms "upstream" and "downstream" mean the direction of the flow of the glass and are understood in their general sense, i.e., along the average direction of movement of the vitrifiable material / glass melt from the inlet means to the outlet means. The expression "upstream section" is understood to mean the first upstream third of the length, and said length is located along the horizontal longitudinal axis of the furnace. The expression "downstream section" is understood to mean the last downstream third of said length.

[0036] Other features and advantages of the present invention will become more apparent by reading the following description of the preferred embodiments and figures given by way of simple illustrative and non-limiting examples.

Brief Description of the Drawings

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Figure 1

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Figure 2

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Figure 3

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Figure 4

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Figure 5

[0042] According to the present invention, as shown in FIG. 1, a method for melting vitrifiable material to produce glass sheets includes first providing a specific furnace, said furnace 1 comprising: (i) a melting tank M comprising at least one upstream zone Z1 covered by a crown C1 and equipped with an electric heating means 2, a downstream zone Z2 covered by a crown C2 and equipped with a combustion heating means 3 and a transition zone T between the crowns C1 and C2, (ii) a refining tank F covered with a crown C4 and equipped with an oxygen combustion heating means 3'; (iii) a neck N, covered by a crown C3, separating the melting tank M from the refining tank F; (iv) at least one inlet means X disposed in the melting tank M; (v) an outlet means O disposed downstream of the purification tank F; and (vi) at least one exhaust gas extraction means arranged in at least one upstream zone Z1 and H1≦0.75 * The height H1 of the crown C1 defined by H2 (where H2 is the height of the crown C2) is 0.25 * (L1+L2)≦L1≦0.8 * At least one upstream zone Z1 has a length L1 defined by (L1+L2) (where L2 is the length of the downstream zone Z2) and LT≦0.2 * The transition zone T has a length LT defined by (L1+L2).

[0043] According to the present invention, and as generally adopted in the glass technology field, a "melting tank" means a tank that defines a zone where a glassifiable material (raw material and / or cullet) is charged and melted by heating. When the furnace is in operation, it includes the melt and a "blanket" of un-melted glassifiable material that floats on the melt, gradually melts, and thus decreases from the upstream to the downstream of the melting tank.

[0044] According to the present invention, and as generally adopted in the glass technology field, a "refining tank" means a tank that defines a zone where no "blanket" of un-melted glassifiable material floating on the melt exists. The glass melt is heated at a temperature higher than the melting tank temperature (generally a temperature exceeding 1400 °C or exceeding 1450 °C) in order to refine the glass (mainly by removing the main part of the bubbles). This refining tank is also generally called a "purification tank" in the art.

[0045] According to the present invention, a "neck" that separates the melting tank and the refining tank means that the width and (crown) height are narrower compared to the downstream zone of the melting tank (zone Z2) and the upstream zone of the refining tank F. The opening of the neck according to the present invention can be only partially under the glass melt / blanket-free surface, leaving a free opening above the glass melt / blanket. This is advantageous because, firstly, it can stabilize the blanket of raw materials and prevent un-melted particles from flowing directly towards the refining tank, and secondly, it can prevent potential defects generated at the contact part of the glass, refractory, and atmosphere from flowing directly into the refining tank. Due to these points, the quality of the glass can be advantageously improved. Furthermore, since a wide opening is possible, the glass velocity decreases, and the corrosion and wear of the refractory decrease. Due to this point, the life of the furnace is advantageously improved.

[0046] Such a furnace design with a zone division of the melting and refining tanks combined with a height division of the melting crown brings many advantages in terms of energy consumption / CO2 emissions and the mechanical stability / life of the furnace.

[0047] In particular, by the combination of (i) separating the melting tank and the purification tank by a neck, and (ii) dividing the melting tank into two zones with different crown heights in a specific design (thereby providing a lower-temperature upstream zone and a higher-temperature downstream zone with a significant temperature difference), while maintaining a high electrical input rate, the total energy consumption of the furnace can be significantly reduced (thereby reducing CO2 emissions), an acceptable surface melting rate can be maintained, and the mechanical stability and lifespan of the furnace are improved.

[0048] The melting crowns C1 and C2 of the present invention take advantage of both the "cold top" zone and the "hot top" zone and are specially designed to create a temperature gradient from the relatively low-temperature (less than 1100 °C) upstream to the relatively high-temperature (higher than 1300 °C) downstream.

[0049] In particular, the furnace of the present invention can fully control (i) the temperature of each zone and (ii) the exhaust gas re-division / extraction between the two zones of the melting tank and between the melting tank and the purification tank in order to optimize energy consumption, avoid alkali corrosion as much as possible, and optimize CO2 capture.

[0050] The furnace of the present invention is further advantageous in that it simultaneously generates a strong temperature difference between the upstream and downstream parts of the melting tank and avoids, as much as possible, the reverse flow of the exhaust gas generated from the purification tank towards the melting tank.

[0051] From the perspective of energy efficiency, - Dividing the atmosphere to confine energy efficiently in the zone where high temperature is required (purification zone) and blocking the heat radiation from the purification tank to the melting tank, and - Extracting the exhaust gas from the upstream part / exit at as low a temperature as possible to limit the waste heating of the gas released from the vitrifiable material and optionally maximize the heat transfer from the combustion gas to the vitrifiable material and the glass melt To enable this, the furnace of the present invention is advantageous.

[0052] From the point of view of surface melting rate, this is advantageous as it allows relatively high temperatures (>1300° C.) to be reached in the downstream part of the melting tank in order to improve the melting rate of the vitrifiable material.

[0053] From a corrosion perspective, - Separation of the atmosphere between the melting tank and the refining tank limits / avoids reflux of waste gases from the refining zone, which are rich in alkalis and therefore highly corrosive due to the high temperatures required for refining; - Having a restriction of the overall molten glass flow, which advantageously reduces the intensity of the glass convection in the melting tank, lowering the glass velocity and thus reducing wear and erosion of the bottom refractory. This is advantageous because it allows

[0054] Finally, the furnace of the present invention, with its specific division (via the neck) between the melting tank and the refining tank, also allows for a complete separation of the dimensions (length, width and crown height) and refractory properties of the melting and refining tanks, thus allowing for the optimization of each tank taking into account energy efficiency, glass quality, factory space constraints and mechanical / structural / other constraints.

[0055] 2 and 3 show an embodiment of a furnace 1 according to the invention (FIG. 2: vertical section, FIG. 3: horizontal section).

[0056] The furnace 1 of the invention includes a melting tank M, a neck N and a refining tank F. The assemblies M, N and F are generally made of refractory materials resistant to temperature, the corrosive effects of fumes and the aggressive action of the molten material. In Fig. 2 the glass melt level (excluding the batch blanket) in an exemplary tank is shown by a dashed line.

[0057] According to the invention, as shown in Figures 2-3, the furnace 1 comprises at least one inlet means X into the melting tank M for charging the vitrifiable raw materials (friction and / or cullet) into the furnace.

[0058] In order to improve distribution on the surface of the melt tank M, several inlet means, i.e. two or three inlet means, located upstream of the melt tank M (in other words in zone Z1), are advantageously provided. Preferably and as known in the art, at least one inlet means X is arranged upstream of the melt tank M transversely across the width of said tank and / or across its length.

[0059] As shown in FIGS. 2-3, the furnace 1 of the present invention includes a melting tank M, which is at least one upstream zone Z1 covered by a crown C1 and equipped with electric heating means 2, a downstream zone Z2 covered by a crown C2 and equipped with electric heating means 2 and combustion heating means 3, - Transition zone T between crown C1 and crown C2 Includes.

[0060] According to an advantageous embodiment, the downstream zone Z2 comprises further electric heating means, as shown in FIGS.

[0061] The electric heating means 2 according to the invention are preferably arranged at the bottom of the melting tank M and also consist of electrodes, 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 obtained. 2 The number of electrodes is designed to respect the above and 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.

[0062] The combustion heating means 3 in the downstream zone Z2 of the melting tank M is particularly composed of burners. In particular, they are generally arranged in rows and are arranged on one or, alternatively, on both sides along the side wall of the zone, for example, to spread the flame over substantially the entire width of the zone. They are alternatively or additionally arranged also on the crown C2, thereby promoting heat transfer to the batch, shortening the length of the batch, and being advantageous for avoiding the batch blanket reaching the end of the downstream zone Z2 and thus the downstream end of the melting tank.

[0063] The combustion heating means 3 can be supplied with fuel and air, or fuel and oxygen, or fuel and oxygen-enriched gas. The fuel can be a fossil fuel, natural gas, biogas, hydrogen, ammonia, synthesis gas or a mixed gas thereof.

[0064] According to an advantageous embodiment, at least one upstream zone Z1 can include further auxiliary combustion heating means (for example, burners, not shown) to enable control of the temperature of the crown C1 (for example, to limit temperature fluctuations along the zone Z1) and to increase the temperature when it drops below a specific level (for example, below 600 °C). In particular, these auxiliary combustion heating means can advantageously be arranged within the crown C1 to reduce the occupancy of the free volume space above the melt / batch blanket.

[0065] The upstream zone Z1 according to the present invention has a crown C1. The downstream zone Z2 according to the present invention has a crown C2.

[0066] According to the present invention, the height H1 of the crown C1 is defined by H1 ≤ 0.75 * by H2, where H2 is the height of the crown C2. In the present invention, the change in height between the crowns C1 and C2 along the melting tank M means the transition zone T.

[0067] As used herein and throughout the claims, the "height" of the crown in the present invention means the average inner height (shown in FIG. 2) from the inner surface of the crown to the glass melt (excluding the batch blanket if present). The height H1 of crown C1 may be substantially constant along the length of the crown or may vary along the length of the crown. The height H1 of crown C1 may be substantially constant along the width of the crown or may vary along the width of the crown (e.g., in the case of an arch / round ceiling crown). The height H2 of crown C2 may be substantially constant along the length of the crown or may vary along the length of the crown. The height H2 of crown C2 may be substantially constant along the width of the crown or may vary along the width of the crown (e.g., in the case of an arch / round ceiling crown).

[0068] According to one embodiment of the present invention, the height H1 of crown C1 is such that H1 ≦ 0.7 * H2, preferably H1 ≦ 0.6 * H2, more preferably H1 ≦ 0.5 * is defined by H2. Thereby, the above-mentioned advantages of the present invention can be enhanced.

[0069] According to the present invention, the length L1 of at least one upstream zone Z1 is such that 0.25 * (L1 + L2) ≦ L1 ≦ 0.8 * is defined by (L1 + L2), where L2 is the length of the downstream zone Z2.

[0070] As used herein and throughout the claims, "length" means the dimension along the flow of the glass.

[0071] According to another embodiment of the present invention, the length L1 of at least one upstream zone Z1 is such that 0.3 * (L1 + L2) ≦ L1, preferably 0.4 * (L1 + L2) ≦ L1, more preferably 0.5 * is defined by (L1 + L2) ≦ L1. Thereby, the above-mentioned advantages of the present invention can also be enhanced.

[0072] According to another embodiment of the present invention, the length L1 of at least one upstream zone Z1 is such that L1 ≦ 0.75 * (L1 + L2), preferably L1 ≦ 0.7 * is defined by (L1 + L2).

[0073] It is worth mentioning that the total length of the melting tank may be slightly higher (for example, on the order of 10% to 15%) than the sum (L1 + L2). In fact, in the art, it is common to provide a first zone Z0 (commonly referred to as a "doghouse") at the very upstream part of the melting tank for the introduction of the vitrifiable material and the extrusion in the melting direction (not shown).

[0074] The crown C1 according to the present invention can be arch-shaped or round ceiling-shaped, or can be flat. Independently of the crown C1, the crown C2 according to the present invention can be arch-shaped or round ceiling-shaped, or can be flat.

[0075] Advantageously, the crown C1 can be composed of a refractory essentially made of silica (for example, high-purity silica). Silica refractories are known to be more vulnerable to corrosion (compared to, for example, alumina), but in the present invention, since there is a neck separating the melting tank and the refining tank, there is less alkali in the fumes present in the melting tank.

[0076] The advantage of silica is that it has a low coefficient of expansion when the temperature is higher than about 600°C, which allows it to withstand high temperature changes without disturbing the upper structure of the crown.

[0077] Alternatively, the crown C1 and / or the crown C2 can be composed of a refractory essentially made of alumina or AZS (alumina - zirconia - silica), which has better resistance to corrosion and thus a longer lifespan.

[0078] According to the present invention, as shown in FIG. 2, the furnace includes a melting tank M including at least one upstream zone Z1 and a downstream zone Z2 having different crown heights C1 having a height H1 and C2 having a height H2.

[0079] In the furnace provided by the method according to the present invention, the change in height between the crowns C1 and C2 along the melting tank M means a transition zone T.

[0080] According to the present invention, the length LT of the transition zone T is LT ≦ 0.2 * (L1 + L2), preferably LT ≦ 0.15 * (L1 + L2), and further LT ≦ 0.1 * is defined by (L1 + L2).

[0081] According to one embodiment, the transition zone T between the crown C1 and the crown C2 can be a partition wall. The partition wall according to one embodiment can be a vertical wall or a short inclined wall (enabling a gradual transition). In this embodiment, the crown C1 preferably has an inner surface substantially at the same height as or slightly lower than the lower edge of the partition wall. The partition wall can be composed of a suspended rear wall. The suspended rear wall according to the present invention is, for example, as described in U.S. Patent No. 5,011,402. Alternatively, the partition wall can lie on the outer surface of the crown C1.

[0082] According to another embodiment, the transition zone T between the crown C1 and the crown C2 is a shadow wall. The "shadow wall" in the present invention means a wall having a lower end extending below the inner surface of the crown C1, thereby being close to the glass melt but leaving a free space above the glass melt. This embodiment further reduces the radiative heat exchange between the upstream zone and the downstream zone of the melting tank, better separates the exhaust gases emitted from Z1 and Z2, and has the advantage that the vitrifiable material extruded from the upstream can pass through the remaining free space. For example, this shadow wall can be an air-cooled suspended wall as known in the art. The shadow wall according to the present invention can be composed of, for example, a suspended U-shaped shadow wall as described in U.S. Patent No. 3,399,046A.

[0083] According to a further embodiment, the transition zone T between the crown C1 and the crown C2 includes at least one step. In a configuration having one step, the change in height between the crown C1 and the crown C2 is obtained by a transition zone T including a first wife wall, a short crown at a height intermediate between H1 and H2, and a second wife wall from C1 to C2. This configuration has the advantage of facilitating the creation of the transition between the crown C1 and the crown C2 and enhancing stability.

[0084] The "length of the transition zone" means, throughout this specification and the claims, the dimension of said zone along the flow of the glass, including the thickness of the wall (even if it lies on and / or overlaps the crown C1 and / or the crown C1).

[0085] According to an advantageous embodiment, the transition zone is composed of a refractory essentially made of silica.

[0086] Advantageously, according to another embodiment, the crown C1 and the transition zone T are made of the same refractory material in order to avoid expansion between materials and / or avoid corrosion between materials. Preferably, it is composed of a refractory essentially made of silica.

[0087] Advantageously, according to another embodiment, the crown C1, the crown C2 and the transition zone T are also made of the same refractory material in order to avoid expansion between materials and / or corrosion between materials. Preferably, it is composed of a refractory essentially manufactured from silica.

[0088] According to the invention, the furnace includes a refining tank F covered by a crown C4 and equipped with oxy-fuel heating means 3'.

[0089] The "oxy-fuel means" 3' according to the invention means a combustion means to which gaseous oxygen (O2) is supplied as a combustion agent. Generally, the O2 gas combustion agent supplied to a glass melting furnace has a purity of at least 90% or at least 95%. The advantage of using gaseous oxygen as a combustion agent is that the so-called corrosive "NOx" pollutants generated during combustion are significantly reduced compared to the case of using air. (Depending on the purity of O2 and the amount of parasitic air), even if they are present in the exhaust gas, they will be in a very small amount.

[0090] The oxy-fuel heating means 3' from the refining tank F according to the invention can advantageously be composed of burners arranged along the side wall of the refining tank. Further, the burners are advantageously arranged at intervals from each other in order to disperse the energy supply to a part of the refining tank F, preferably the upstream part (for example, about 50% of the length). They are generally arranged in rows on one side or instead on both sides of the refining tank F, preferably in a staggered arrangement (in order to spread the flame over substantially the entire width of the tank).

[0091] The crown C4 according to the invention is preferably of an arch type or a round ceiling type.

[0092] According to an advantageous embodiment, the refining tank F may include further electrical heating means (not shown), particularly in the upstream part of the refining tank (for example, about 50% of the length). Thereby, the electrical input rate can be increased, and as a result, the energy efficiency can be improved and the CO2 emissions can be reduced.

[0093] According to the invention, the furnace comprises a neck N which is covered by a crown C3 and separates / divides the melting tank M and the refining tank F.

[0094] According to the invention, the "neck" separating the melting tank M and the refining tank F means a narrowing in width and (crown) height compared to the downstream zone of the melting tank (zone Z2) and compared to the upstream zone of the refining tank F. The opening of the neck according to the invention is only partially below the glass melt / batch blanket free surface and then leaves a free opening above the glass melt / batch blanket.

[0095] According to the definition of the neck according to the present invention, the width W of the neck N N is as follows: N <W M And W M is the width of the melting tank. According to the definition of the neck according to the present invention, the width W of the neck N is N is as follows: N <W F But, W F is the width of the purification tank F.

[0096] In the present invention, "width" means the dimension (average) perpendicular to the flow of glass throughout this specification and claims.

[0097] 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 M (Zone 1 and / or Zone 2) and the off-gases from the refining tank independently, if necessary.

[0098] The base of the neck N in the present invention can be essentially located at the level of the floor / bottom of the melting tank M, or can be located above or below said level. Further, the base of the neck N can be substantially located at the level of the floor / bottom of the refining tank F, or can be located above or below said level.

[0099] According to one embodiment, the neck N does not include any heating means, for example any electric heating means.

[0100] The crown C3 according to the present invention can be arch-shaped or round ceiling-shaped, or can be flat. According to the definition of the neck according to the present invention, the crown C3 of the neck N has a height H3 that is lower than the height H2 of the crown C2 of the melting tank M. According to the definition of the neck according to the present invention, the crown C3 of the neck N also has a height H3 that is lower than the height H4 of the crown of the refining tank F.

[0101] According to yet another advantageous embodiment of the present invention, the furnace can include a removable wall (e.g., a skin baffle coming from the side wall of the neck) located in the neck to (i) stop unmolten vitrifiable materials that can reach the ends of the melting tank, thereby preventing them from heading towards the refining tank through the neck, and (ii) control or eliminate the intensity of the reverse flow of the glass melt from the refining tank towards the melting tank.

[0102] According to yet another advantageous embodiment of the present invention, the furnace can include a removable wall (e.g., a shadow wall passing through the crown of the neck section) located in the neck section to enhance the separation of the melting tank and the refining tank in terms of atmosphere and thermal radiation.

[0103] According to the present invention, the furnace includes outlet means O located downstream of the purification tank F for the molten glass to reach the working zone. According to one embodiment, the outlet means O generally consists of a neck to guide the melt to a working zone also commonly referred to as the "working end", or "flare", or "conditioning zone". Alternatively, the outlet means O consists of a throat (i.e., an opening that is completely immersed in the glass melt and leaves no free surface thereon) to guide the melt to a working zone including, for example, a forehearth. The working zone according to the present invention may include, for example, a conditioning zone where thermal conditioning by controlled cooling is performed before the glass melt exits through the outlet to the forming zone. Such a forming zone may consist of, for example, a float facility and / or a rolling facility.

[0104] According to the present invention (as shown in FIGS. 2 and 3), the furnace includes at least one upstream zone Z1, preferably at least one exhaust gas extraction means 4 arranged in the vicinity of the inlet means X, for recovering heat and transferring it from the exhaust gas to the glass melt and / or the unmolten glassifiable material in the melting tank M.

[0105] According to one embodiment of the present invention, the furnace further includes at least one exhaust gas extraction means in the downstream zone Z2 and / or at least one exhaust gas extraction means in the purification tank F (not shown).

[0106] If there is an extraction means in the zone Z2, this advantageously allows the extraction of exhaust gas from the downstream zone Z2, especially when the gas is alkali-rich (thereby avoiding condensation and subsequent corrosion in the zone Z1).

[0107] If there is an extraction means in the purification tank F, it is preferably arranged in the upstream part of the purification tank.

[0108] Preferably, in the present invention, the extraction means 4 is arranged on one or both side walls.

[0109] In particular, in the present invention, it is energetically advantageous for the exhaust gas to be extracted maximally from upstream of the furnace, in particular from upstream of the melting tank. For example, at least 25% of the combustion exhaust gas generated in the melting zone can be advantageously extracted from upstream of the melting tank. Nevertheless, extracting a part of the exhaust gas from downstream of the melting tank can be advantageous in order to limit the risk regarding the alkali attack of the crown refractory. In fact, the evaporation of alkali increases with temperature, and the alkali concentration in the exhaust gas becomes higher in the downstream part of the melting zone. Since the exhaust gas with a higher alkali concentration can cause problems related to condensation in the cooler regions of the superstructure / crown, it is better to discharge it from the downstream. Furthermore, in its upstream zone, the exhaust gas essentially results from the gases released from the decomposition of the raw materials and is therefore poor in alkali, so it is advantageous to extract a part of the exhaust gas from upstream of the melting tank. Finally, since the temperature required for purification is higher and the exhaust gas from the purification tank contains more alkali, it is also advantageous to extract a part of the exhaust gas from the purification tank.

[0110] Furthermore, in the present invention, it is even more advantageous that the exhaust gas generated from the decomposition of the raw materials (at least its main part) at upstream Z1 of the melting tank can be extracted (and thereby processed) almost independently of the exhaust gas coming from combustion (in zone Z2 and / or the purification tank). In fact, the exhaust gas generated in zone Z1 is poor in NOx and SOx, so the recovery of CO2 is easy.

[0111] In an advantageous embodiment of the present invention shown in FIG. 4, the furnace of the present invention includes a melting tank M that is expanded in the lateral direction and includes inlet means X' and X'' arranged in each lateral direction. The melting tank includes two different upstream zones Z1' and Z1'' and two transition zones T' and T'', and two opposing glass flows converge through the central downstream zone Z2.

[0112] In this configuration, - The height H1' of the melting crown C1' is such that H1'≦0.75 * is defined by H2, - The height H1'' of the molten crown C1'' is such that H1'' ≤ 0.75 * is defined by H2, - The length L1' of at least one upstream zone Z1' is 0.25 * (L1'+L2) ≤ L1' ≤ 0.8 * is defined by (L1'+L2), - The length L1'' of at least one upstream zone Z1'' is 0.25 * (L1''+L2) ≤ L1'' ≤ 0.8 * is defined by (L1''+L2), - The length LT' of the transition zone T' is such that LT' ≤ 0.2 * is defined by (L1'+L2), and - The length LT'' of the transition zone T'' is such that LT'' ≤ 0.2 * is defined by (L1''+l2).

[0113] Also, in this configuration, - The melting tank includes one downstream crown C2 and two upstream crowns C1' and C1''. The crowns C1' and C1'' can be independently configured according to any embodiment of the invention related to the crown C1. For example, the upstream crowns C1' and C1'' can have the same or different heights H1' and H1'', - The melting tank includes two transition zones T' and T''. They can be independently configured according to any embodiment of the invention related to the transition zone T.

[0114] In this configuration, for example, the combustion heating means 3 is arranged, as shown in FIG. 4, on the melting tank wall facing the neck, for example, like two burners. Alternatively, for example, the combustion heating means 3 is arranged on the crown C2.

[0115] In this advantageous configuration / embodiment, each upstream zone, each upstream crown and each inlet means are according to the invention and its embodiments and can be designed independently of the other upstream zones, upstream crowns and inlet means respectively according to the above description. Thus, for clarity, the features described above in relation to Z1 are independently applicable to Z1' and Z1'', the features described above in relation to C1 are independently applicable to C1' and C1'', the features described above in relation to T are independently applicable to T' and T'', and the features described above in relation to X are independently applicable to X' and X''. Furthermore, the specific advantageous features described in relation to M, C2, C3, C4, N, F, etc. are also applicable to this specific configuration and have the same advantages.

[0116] The design of a specific glass furnace having a division by a neck between the melting tank and the refining tank is described in European Patent No. 21200998.9, which is incorporated herein by reference as an embodiment of the present invention.

[0117] According to a specific embodiment, the furnace of the present invention 0.1 * W F ≦W N ≦0.6 * W F 、 W M ≧1.4 * W N is defined by W M is the width of at least one melting tank M, W F is the width of the refining tank F, W N is the width of at least one neck N.

[0118] This embodiment can enhance the above advantages of the present invention, in particular, - can better separate the atmosphere between the melting tank and the refining tank and limit the reflux of corrosive fumes from the refining tank to the melting tank, - The heat radiation shielding from the refining tank to the melting tank can be enhanced, - The overall restriction of the molten glass flow can be enhanced or backflow can be eliminated.

[0119] Preferably, the furnace is 0.2 * W F ≦W N ≦0.6 * W F or 0.3 * W F ≦W N ≦0.5 * W F defined by. Thereby, a good compromise between the following two conflicting requirements can be found. On the one hand, (1) the opening between the melting superstructure / crown and the refining superstructure / crown is reduced, and (2) the neck between the melting zone and the refining zone should ideally be as narrow as possible in order to cause an obstacle to the convection intensity of the total glass melt in the melting tank. On the other hand, the neck should ideally be as wide as possible in order to limit the glass velocity inside the neck and limit the wear / corrosion of the neck refractory wall.

[0120] Preferably, the furnace of the present invention is W M ≧1.5 * W N or W M ≧1.8 * W N also defined by. More preferably, the furnace of the present invention is WM≧2 * W N defined by. Thereby, the width limitation of the neck N becomes larger, the heat radiation shielding is improved, better atmosphere separation becomes possible, and the molten glass flow is restricted.

[0121] According to an embodiment, 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 embodiments are extensively described in European Patent Application Publication No. 21200998.9 which is incorporated herein by reference.

[0122] In the specific "two melting tanks" configuration shown in FIG. 5, the furnace for melting the vitrifiable material includes two melting tanks M' and M'', two necks N' and N'' (one for each melting tank), and at least two inlet means X' and X'' (one for each melting tank).

[0123] This configuration is particularly advantageous compared to the configuration with one melting tank (FIG. 3) because the following are possible: - It is possible to reduce the crown span of each melting tank for the same total melting tank area and furnace length (length is generally more restrictive than width). By reducing the crown span, (i) the stress inside the crown material is reduced, and then the risk regarding creep and sagging of the material is reduced. As a result, it becomes possible to use refractories with higher resistance to corrosion such as alumina or spinel and lower resistance to creep, and it becomes possible to increase the life of the furnace, (ii) in the case of arch-shaped crowns C1 and / or C2, it is possible to reduce the average height of the crown, reduce the horizontal radiative transfer, and then, when the exhaust gas is extracted from the melting tank, achieve good heat transfer from the exhaust gas to the glass melt, - For the same total neck width (W N’ +W N’’ ) and in the case of an arch-shaped neck crown C3, it is possible to reduce the opening area between the melting tank and the refining tank, - For the same total neck width (W N’ +W N’’ ), it is possible to reduce the intensity of glass convection in the melting tank, - It is possible to facilitate the maintenance of the furnace in the melting zone. In fact, when there are two melting tanks, it is possible to isolate and cool one melting tank from the other parts of the furnace and carry out production in the other melting tank. Therefore, by replacing the worn refractories in the melting zone, which is the most important area regarding wear / corrosion, it is possible to increase the life of the entire furnace.

[0124] In this configuration, the furnace comprises two melting tanks M', M'', each having its upstream zone, Z1' or Z1'', its upstream crown, C1' or C1'', its downstream zone, Z2' or Z2'', its transition zone, T' or T'', and its inlet means, X' or X''. Furthermore, each melting tank M' and M'' is separated from the refining tank F by a neck N' and N'', respectively.

[0125] In this configuration, according to the present invention, - The height H1' of the fusion crown C1' is H1'≦0.75 * Defined by H2', - The height H1'' of the fusion crown C1'' is H1''≦0.75 * Defined by H2'', - The length L1' of the upstream zone Z1' is 0.25 * (L1'+L2')≦L1'≦0.8 * (L1'+L2'), and - The length L1'' of at least one upstream zone Z1'' is 0.25 * (L1''+L2'')≦L1''≦0.8 * (L1''+L2'', - The length LT' of the transition zone T' is LT'≦0.2 * (L1'+L2'), - The length LT of the transition zone T is LT≦0.2 * It is defined by (L1''+L2'').

[0126] According to this particular embodiment, the furnace advantageously comprises: 0.1 * W F ≦W N’ ≦0.6 * W F , 0.1 * W F ≦W N’’ ≦0.6 * W F , W M’ ≧1.4* W N’ 、 W M’’ ≧1.4 * W N’’ may be defined by W M’ is the width of at least one melting tank M', W M’’ is the width of at least one melting tank M'', W F is the width of the purification tank F, W N’ is the width of the neck N', W N’’ is the width of the neck N''.

[0127] Also, in this configuration, - The upstream zone and the downstream zone can be independently configured according to any embodiment of the present invention related to Z1 and Z2, respectively. - The crowns C1' and C1'' can be independently configured according to any embodiment of the present invention related to the crown C1, respectively. For example, the upstream crowns C1' and C1'' may have the same or different heights H1' and H1''. - The crowns C2' and C2'' can be independently configured according to any embodiment of the present invention related to the crown C2, respectively. For example, the crowns C2' and C2'' may have the same or different heights H2' and H2''. - The transition zones T' and T'' can be independently configured according to any embodiment of the present invention related to the transition zone T, respectively.

[0128] In this advantageous configuration / embodiment, each melting tank, each upstream zone, each downstream zone, each transition zone, each neck and each inlet means are according to the invention and its embodiments and can be designed independently of other melting tanks, upstream zones, downstream zones, transition zones, necks and inlet means respectively according to the above description. Thus, for clarity, the features described above in relation to M are applied independently to M' and M'', the features described above in relation to Z1 are applied independently to Z1' and Z1'', the features described above in relation to C1 are applied independently to C1' and C1'', the features described above in relation to Z2 are applied independently to Z2' and Z2'', the features described above in relation to C2 are applied independently to C2' and C2'', the features described above in relation to T are applied independently to T' and T'', and the features described above in relation to X are applied independently to X' and X''.

[0129] Furthermore, the specific advantageous features described in relation to a furnace having one melting tank (e.g., those described in relation to C3, C4, F) are applied such that similar advantages exist in this "two melting tank" configuration.

[0130] In a "two melting tank" furnace according to one embodiment, the two melting tanks M', M'' are preferably connected to the purification tank F by two necks N', N'' located at the width W F of the purification tank F (shown in Figure 5). Alternatively, in the "two melting tank" configuration, the first melting tank is connected to the purification tank by a neck located at the width W F of the purification tank, and the second melting tank is connected to the purification tank by a neck located at the length of the purification tank (right or left) close to the upstream of the purification tank (i.e., the first third of its length). This last configuration is advantageous, for example, when the space available in the plant housing the furnace is not sufficient to arrange the two melting tanks side by side.

[0131] In the "two melting tank" configuration, the two melting tanks are at the width W FWhen connected to the purification tank by a neck located at [location not specified in the original], the distance D between the two melting tanks is preferably at least 1 m, more preferably at least 2 m, even more preferably at least 3 m. This is advantageous to allow access to the maintenance work and the zone for tank wall overcoating.

[0132] In another embodiment of the present invention, the furnace has a configuration having three melting tanks, three necks and three inlet means. This embodiment is particularly advantageous compared to the configuration having one melting tank, as well as the "two melting tanks" configuration. In this "three melting tanks" configuration, each neck, each melting tank and each inlet means are according to the present invention and its embodiments and can be designed independently of the other necks, melting tanks and inlet means according to the above description.

[0133] The specific advantageous features described in relation to furnaces having "one melting tank" and "two melting tanks" are also applicable to the "three melting tanks" configuration and have the same advantages.

[0134] In a "three melting tanks" furnace according to an embodiment, when at least two melting tanks are connected to the purification tank by a neck located at the width W of the purification tank F the distance D between two adjacent melting tanks is preferably at least 1 m, more preferably at least 2 m, even more preferably at least 3 m.

[0135] In all furnace configurations according to the present invention, i.e., the "one melting tank", "two melting tanks" and "three melting tanks" configurations, one or more charging means can be provided for each melting tank to facilitate the distribution of the vitrifiable material into the charge, i.e., two charging means can be provided for each melting tank.

[0136] Preferably, the total surface area of the melting tank is 25 - 400 m 2 Similarly preferably, according to the present invention, the surface area of the purification tank is 25 - 400 m 2is as follows.

[0137] According to the present invention, and as shown in FIG. 1, a method for producing sheet glass by melting a vitrifiable material includes charging a vitrifiable material including raw materials and cullet into at least one melting tank M using at least one inlet means.

[0138] According to the present invention, since the vitrifiable material includes raw materials and cullet, preferably, both are charged together into the melting tank M, that is, through the same inlet means X. Alternatively, both are charged independently into the melting tank M through different inlet means X (for example, one inlet means for raw materials and one inlet means for cullet or two inlet means for raw materials and two inlet means for cullet).

[0139] According to the present invention, the amount of cullet is at least 10% by weight of the total amount of the vitrifiable material. Preferably, the amount of cullet is at least 20% by weight of the total amount of the vitrifiable material. More preferably, the amount of cullet is at least 30% by weight of the total amount of the vitrifiable material, and even more preferably at least 40% by weight. This is advantageous because it can reduce the CO2 generation / emission of the method of the present invention (for reducing the emission generated 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 the 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 the vitrifiable material.

[0140] According to the present invention, the raw material contains less than 25% by weight of carbonate compounds. "Carbonate compounds" means, for example, alkali carbonates and alkaline earth carbonates. Preferably, the raw material contains less than 20% by weight, more preferably less than 10% by weight, and even more preferably less than 5% by weight of carbonate compounds. Advantageously, the raw material may not contain any carbonate compounds.

[0141] This is advantageous because it can reduce a part of the CO2 emissions resulting from the decarbonation of the raw materials as compared to the classical glass melting method in which sodium carbonate Na2CO3, limestone CaCO3 and dolomite CaMg(CO3)2 are generally essentially used as sodium, calcium and magnesium sources. According to this embodiment, the alkali source and the alkaline earth source can preferably be present at least partially in the form of oxides or hydroxides such as CaO, CaO·MgO (dolomite), Ca(OH)2, Mg(OH)2, NaOH, KOH and the like. According to the present invention and as shown in FIG. 1, a method for melting a vitrifiable material to produce sheet glass includes melting the vitrifiable material in a melting tank M by heating with heating means, that is, electric heating means 2 and combustion heating means 3.

[0142] According to the present invention and as shown in FIG. 1, a method for melting a vitrifiable material to produce sheet glass includes purifying the melt in a purification tank F by heating with oxygen combustion heating means 3' supplied with gas and / or hydrogen. As used herein, the term "gas" includes, but is not limited to, natural gas, synthesis gas and biogas. Natural gas is currently the most widely used in terms of practicality, economy and availability.

[0143] According to the present invention, the oxygen combustion heating means 3' is supplied with gas and / or hydrogen. In one embodiment, the oxygen combustion heating means 3' is supplied with at least 50% hydrogen, preferably at least 80% hydrogen. More preferably, the oxygen combustion heating means 3' is supplied with 100% hydrogen. This is advantageous because it can dramatically reduce the total CO2 emissions of the method. Alternatively, the oxygen combustion heating means is supplied with more than 50%, preferably at least 80%, and further at least 100% gas. This is advantageous because it can reach a higher CO2 concentration in the exhaust gas, not only facilitating and improving the capture of CO2, but also suppressing the influence on the chemical properties of the glass and the furnace refractory materials. In a specific and advantageous embodiment of the present invention, the oxygen combustion heating means 3' is supplied with 50% gas and 50% hydrogen.

[0144] According to the present invention, the electrical input rate in the method is 30% - 85%. The "electrical input rate" according to the present invention means the portion of electricity in the total energy input of the method / furnace for melting / purifying, that is, electricity / (fuel + electricity), and the total energy input is that of the method / furnace in the standard / normal production mode, that is, in its standard pull range (excluding the periods of startup, maintenance, high-temperature repair, caulking). Preferably, the electrical input rate is 35% - 85%, more preferably 40% - 85%.

[0145] According to the present invention, and as shown in FIG. 1, a method for melting a vitrifiable material to produce sheet glass includes flowing the melt from the refining tank F through the outlet means O into the working zone.

[0146] According to the present invention, the outlet means O is arranged downstream of the refining tank F such that the molten glass reaches the working zone. According to one embodiment, the outlet means generally consists of a neck, usually, to direct the melt towards the working zone, generally called the "working end". Alternatively, the outlet means consists of a throat to direct the melt into the working zone, for example, including a forehearth. The working zone according to the present invention may include, for example, an adjustment zone where thermal adjustment by controlled cooling is performed before the glass melt exits through the outlet into the forming zone. Such a forming zone may include, for example, a float facility and / or a rolling facility.

[0147] According to the present invention, and as shown in FIG. 1, a method for melting a vitrifiable material to produce sheet glass includes capturing CO2 from the exhaust gas.

[0148] According to the present invention, the exhaust gas (i.e., the exhaust gas after CO2 capture) has a CO2 concentration of at least 35%. The CO2 concentration according to the present invention is a concentration defined for dry exhaust gas, i.e., exhaust gas containing all components except water (H2O). Preferably, the exhaust gas in the present invention has a CO2 concentration of at least 40%, more preferably at least 50%, and even more preferably at least 60%. The higher the CO2 concentration of the exhaust gas, the easier and more effective the CO2 capture applied to this exhaust gas, so this is advantageous.

[0149] According to the present invention, capturing CO2 from the exhaust gas includes compressing and / or dehydrating. Dehydrating corresponds to compressing and / or drying the water in the exhaust gas. Compressing generally corresponds to increasing the pressure of CO2 by using a compressor. Dehydrating can be before compressing, and / or dehydrating can be simultaneous with compressing.

[0150] In particular, capturing CO2 from the exhaust gas according to the present invention can be carried out by known methods using a CO2 compression and purification unit (or CPU).

[0151] As shown in Figure 1, the exhaust gas according to the present invention can be recovered from the melting tank M or the purification tank F or both for CO2 capture. In particular, when only hydrogen is supplied to the oxy-fuel heating means 3' according to the present invention, the exhaust gas is preferably recovered only from the melting tank M (the exhaust gas generated from the purification tank F does not contain CO2).

[0152] After the capture of CO2 according to the present invention, the CO2 product has, for example, a pressure of about 35 bar at a temperature of 5°C to 40°C and is in gaseous form, suitable for transportation through a pipeline or has a pressure of about 100 bar and is in liquid form, suitable for transportation through a pipeline but also suitable for truck or railway transportation. It is also known that 15 barg at -35°C is suitable for transportation by truck.

[0153] This simple and effective CO2 capture method can avoid the use of any adsorbents / chemical reagents that contribute to operating / energy costs and environmental problems, enabling cost-effective CO2 capture and making the overall method of the present invention economically viable, which is highly advantageous.

[0154] According to a preferred embodiment, capturing CO2 from the exhaust gas essentially involves compressing and / or dehydrating.

[0155] According to an advantageous embodiment, the method of the present invention further includes removing acidic components from the exhaust gas. Removing acidic components is carried out before or simultaneously with (e.g., before or simultaneously with / along with compressing and / or dehydrating) capturing CO2.

[0156] Removing acidic components may include desulfurizing the exhaust gas (or removing so-called "SOx" compounds). Since oxygen is used as a supporting combustion substance, it may also include removing so-called "NOx" compounds that may exist even in very small amounts. This is advantageous because corrosive compounds (SOx, NOx) can be removed before transportation, storage, and / or utilization.

[0157] After capturing CO2 according to the present invention, in a known method, the CO2 product (e.g., in liquid form) is transported through a pipeline to its final destination and can then be stored / reserved (e.g., in a formation such as a deep seabed or saline aquifer) or utilized (e.g., for enhanced oil recovery, food / beverage applications, or fire prevention purposes). Advantageously, the CO2 product obtained after CO2 capture can be used locally to limit transportation. This can be considered when the amount of captured CO2 is not too high so that it can be absorbed in the local market.

[0158] According to an advantageous embodiment of the present invention, the method further comprises preheating the cullet by recovering at least partially the heat from the furnace 1 before charging the cullet into at least one melting tank M. According to this embodiment, the heat recovery from the furnace 1 can be carried out from the exhaust gases exiting from (i) the melting tank M, or (ii) the refining tank F, or (iii) the furnace as a whole (including thus the exhaust gases from the melting and refining tanks).

[0159] According to this embodiment, advantageously, the CO2 capture can be carried out from the exhaust gases used for preheating the cullet.

[0160] According to this embodiment, the raw materials are charged into the melting tank together with the preheated cullet through the same inlet means (thus, this means that both types of vitrifiable materials are mixed before charging). Alternatively, the raw materials are charged into the melting tank M through different inlet means, independently of the preheated cullet.

[0161] Preferably, according to this embodiment, the maximum temperature of the cullet in preheating the cullet is 450 °C. This can avoid the problem of clogging.

[0162] According to this embodiment, preheating the cullet can be carried out, for example, in at least one cullet preheater of one of the types described in US Patent No. 5,526,580 or German Patent No. 3,716,687.

[0163] Advantageously, at least one cullet preheater can be arranged either transversely to the width or the length of the tank upstream of the melting tank. Advantageously, preheating the cullets can be carried out, for example, by means of at least two cullet preheaters arranged on both sides transversely to the width or the length of the melting tank upstream thereof. For example, preheating the cullets can be carried out by means of four cullet preheaters distributed transversely to the width or the length of the melting tank upstream thereof (for example, two on each side). For example, preheating the cullets can also be carried out by means of six cullet preheaters arranged transversely to the width or the length of the melting tank upstream thereof (for example, three on each side) or, likewise, by means of eight cullet preheaters arranged transversely to the width or the length of the melting tank upstream thereof (for example, four on each side).

[0164] According to another advantageous embodiment of the invention, the method further comprises pre-melting at least a part of the cullets in an auxiliary melting tank and flowing the pre-melted cullets into the melting tank (therefore called the "main melting tank"). According to this embodiment, a part of the cullets to be pre-melted is charged into the auxiliary melting tank and, if there is a remaining part of the cullets (not pre-melted), it is charged into the main melting tank. This embodiment has the advantage of preventing a shortage of available high-quality cullets since it allows the use of lower-quality or contaminated cullets in the method of the invention. In fact, in this embodiment, at least a part of the cullets is "digested" in advance in the auxiliary melting tank. For example, metal compounds present in the cullets can be removed in this auxiliary melting tank by using a reducing agent (such as coke or anthracite) and separated molten metal can be produced 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. According to this embodiment, the auxiliary melting tank is preferably connected upstream of the main melting tank M, more preferably connected as upstream as possible of the main melting tank M.

[0165] According to this embodiment of the invention, only a portion of the cullet is also 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 the main melting tank. Alternatively, the entire amount of the cullet is premelted in the auxiliary melting tank.

[0166] Further, according to this embodiment of the invention, preferably the method includes preheating at least a portion of the cullet prior to charging it into the auxiliary melting tank, at least in part by recovering heat from the furnace 1.

[0167] An example of an auxiliary melter tank suitable for this embodiment is described in EP 2 137 115 A1.

[0168] According to a highly preferred embodiment of the present invention, a method of melting vitrifiable material to produce glass sheets comprises: (i) a main melting tank M comprising at least one upstream zone Z1 covered by a crown C1 and equipped with electrical heating means 2, a downstream zone Z2 covered by a crown C2 and equipped with combustion heating means 3 and a transition zone T between the crowns C1 and C2, (ii) Auxiliary melting tanks; (iii) a refining tank F covered with a crown C4 and equipped with an oxygen combustion heating means 3'; (iv) a neck N, covered by a crown C3, separating the main melting tank M from the refining tank F; (v) at least one inlet means X disposed in the main melter tank M; (vi) an outlet means O disposed downstream of the purification tank F; and (vii) at least one exhaust gas extraction means arranged in at least one upstream zone Z1;

[0023] providing a furnace comprising: However, the furnace has a H1≦0.75 * The height H1 of the crown C1 defined by H2 (where H2 is the height of the crown C2) is 0.25* (L1+L2)≦L1≦0.8 * At least one upstream zone Z1 has a length L1 defined by (L1+L2) (where L2 is the length of the downstream zone Z2) and LT≦0.2 * having a length LT of a transition zone T defined by (L1+L2), - charging vitrifiable material into the main melting tank M and / or into the auxiliary melting tank M by means of at least one inlet means, said vitrifiable material comprising (i) raw materials having a weight percentage of less than 25% carbonate compound, and (ii) cullet in an amount of at least 10% by weight of the total amount of vitrifiable material; - preheating the cullet before it is charged into the main melting tank M and / or into the auxiliary melting tank, at least in part by recovering heat from the furnace; - premelting at least a portion of the cullet in an auxiliary melting tank and flowing the premelted cullet into a main melting tank M; - melting the vitrifiable material in the main melting tank M by means of the heating means 2, 3; - refining the melt in a refining tank F by heating using oxy-combustion heating means 3' supplied with gas and / or hydrogen; - flowing the melt from the purification tank F through outlet means O into the working zone; - Capture CO2 from exhaust gases with a CO2 concentration of at least 35% However, the electricity input rate is between 30% and 85%, and capturing CO2 from the flue gas includes compression and / or dehydration.

[0169] All the specific embodiments described above relating to each step of the method of the invention apply to this last highly preferred embodiment.

[0170] Those skilled in the art will understand that the present invention is in no way limited to the above-described preferred embodiments. Rather, many modifications and variations are possible within the scope of the appended claims. Further, it should be noted that the present invention relates to all possible combinations of the features described herein and the preferred features recited in the claims.

Claims

1. A method for melting a vitrifiable material for manufacturing plate glass, comprising the following: (i) A molten tank M including at least one upstream zone Z1 covered by a crown C1 and equipped with an electric heating means 2, a downstream zone Z2 covered by a crown C2 and equipped with a combustion heating means 3, and a transition zone T between the crown C1 and the crown C2. (ii) A purification tank F covered with a crown C4 and equipped with an oxygen combustion heating means 3', (iii) A neck N covered by a crown C3 and separating the melting tank M and the refining tank F, (iv) At least one inlet means X located in the molten tank M, (v) an outlet means O located downstream of the refining tank F, and (vi) at least one exhaust gas extraction means located in the at least one upstream zone Z1 To provide a furnace 1 including, However, the furnace has H1 ≤ 0.75 ＊ The height of the crown C1 is defined by H1 (where H2 is the height of the crown C2), H1, 0.25 ＊ (L1+L2)≦L1≦0.8 ＊ The length L1 of the at least one upstream zone Z1 is defined by (L1 + L2) (where L2 is the length of the downstream zone Z2), and LT ≤ 0.

2. ＊ The transition zone T has a length LT defined by (L1 + L2), - The vitrifiable material, including the raw materials and cullet, is charged into the molten tank M using the at least one inlet means X, wherein the amount of cullet is at least 10% by weight of the total amount of the vitrifiable material, and the raw materials contain less than 25% by weight of a carbonate compound. - Using the heating means 2 and 3, melt the vitrifiable material in the melting tank M. - The molten material is purified in the purification tank F by heating using the oxygen combustion heating means 3' supplied with gas and / or hydrogen. - The molten material is flowed from the refining tank F through the outlet means O to the work zone. - At least 35% CO ２ CO from exhaust gas with concentration ２ To capture However, the electricity input rate is 30% to 85%, and CO2 is released from the exhaust gas. ２ Capturing includes compressing and / or dehydrating.

2. The method for melting a vitrifiable material according to claim 1, characterized in that the amount of cullet is at least 30% by weight of the total amount of the vitrifiable material.

3. The method for melting a vitrifiable material according to claim 1 or 2, characterized in that the oxygen combustion heating means is supplied with at least 50% hydrogen, preferably at least 80% hydrogen.

4. The exhaust gas contains at least 40% CO ２ A method for melting a vitrifiable material according to claim 1 or 2, characterized by having a concentration.

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

6. CO from exhaust gases ２ A method for melting a vitrifiable material according to claim 1 or 2, characterized in that capturing essentially includes compressing and / or dehydrating.

7. A method for melting a vitrifiable material according to claim 1 or 2, further comprising removing acidic components from the exhaust gas.

8. Removing acidic components from the aforementioned exhaust gas is CO ２ A method for melting a vitrifiable material according to claim 7, characterized in that it takes place before or simultaneously with capturing the material.

9. A method for melting a vitrifiable material according to claim 1 or 2, further comprising the step of preheating the cullet by recovering at least partially the heat from the furnace before charging the cullet into the molten tank M.

10. The method for melting a vitrifiable material according to claim 9, characterized in that the maximum temperature of the cullet in the step of preheating the cullet is 450°C.

11. A method for melting a vitrifiable material according to claim 1 or 2, further comprising 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 melting tank M.

12. A method for melting a vitrifiable material according to claim 1 or 2, characterized in that the raw material contains less than 10% by weight of a carbonate compound.

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