Glass furnace with submerged burner including anti-sloshing barrier

Abstract

A plant (1) for melting a raw material composition (5) suitable for obtaining glass wool, rock wool, textile glass fibers and / or sheet glass or hollow glassware, comprising a melting chamber (8) provided with at least one inlet (12), at least one outlet (11) and at least one submerged burner (2) adjacent to said outlet (11). The facility comprises a barrier (10) arranged between the proximal burner and the outlet, intended to limit the sloshing movement of the glass, in particular at the surface of the molten bath.

Description

[0001] The invention relates to an installation for melting raw material compositions suitable for obtaining glass fibers and / or rock fibers of the mineral wool type, "reinforced" woven glass fibers and / or flat glass for thermal or acoustic insulation.

[0002] In this article, these "raw materials" first include vitrifiable materials that enable the target mineral composition of glass or rock or silicate type to be obtained. These vitrifiable materials include silica sand, but also include all additives (sodium carbonate, limestone, dolomite, aluminum, etc.) and any type of broken glass. In the specification, the terms "liquid glass" and "glass melting pool" refer to the molten products of these vitrifiable materials. The raw material composition also includes recyclable materials containing (organic) fuel components, such as waste from the sizing of mineral fibers containing (types for heat insulation or sound insulation or for strengthening plastic materials) adhesives, which originate from the production plant (manufacturing plant) of the fiber, the site (construction or demolition) and / or the recycling stream that can reclaim such fibers from the final product (whether they are used final products). Such mineral fibers can be composed of glass and / or rock in particular. They are therefore respectively referred to as glass wool and rock wool. Also included are laminated glazing with polymer sheets of polyvinyl butyral type, such as windshields, glass bottles (household broken glass) or any type of "composite" materials combining glass and plastic materials, such as some bottles. "Glass-metal composites or metal compounds" can also be recycled, such as glazing units coated with enamel layers, metal layers and / or various connecting elements. Also included among the raw materials are all forms of biomass, i.e. organic matter of plant, animal, bacterial or fungal origin, which can be used primarily as fuel, but also as raw material for influencing the composition of the manufactured vitrifiable material, since its ash content is usually not zero.

[0003] The present invention more particularly relates to so-called "submerged burner" facilities (furnaces). Such burners are usually fed with a mixture of oxygen and fuel gas, or a mixture of air and fuel gas, and are usually arranged so that they are flush with the bottom of the melting chamber, thereby forming a flame in a large amount of raw materials that are liquefied. These burners can make their gas supply lines flush with the wall through which they pass. According to some embodiments, it is also possible to choose to only spray the gas produced by the combustion, which is carried out outside the melting chamber itself.

[0004] As is known, the bottom part of the melting chamber of such facilities comprises a raw material inlet or submerged inlet located below the theoretical level of the molten raw material pool (also referred to as the glass bath throughout this specification). The raw materials are usually fed into the melting chamber by a feeder, which comprises a main body with a sheath and a mechanical system for conveying the raw materials, which is in the form of a piston or a worm. Thereafter, the molten mixture leaves the furnace via a dedicated outlet for subsequent fiberizing glass wool or spinning glass fabric fibers. The one or more inlets and one or more outlets of the furnace are adapted to allow the introduction of raw materials on the one hand, and on the other hand, to simultaneously allow the extraction of molten material, so that the liquid level of the glass bath remains substantially constant throughout the melting process. The amount of molten material at the furnace outlet per unit time (e.g., in tons / day) is referred to as load.

[0005] One disadvantage of the known technology is the variation of this load observed by the inventors in a relatively short period of time. Such variations of the output rate (hereinafter also referred to as instabilities) are detrimental to the quality of the product obtained after forming. In fact, the instantaneous variation of the glass load leads to instabilities in the fiberization, thereby generating more waste. Another disadvantage is that the amount of fiber produced at a given moment also varies, which is not conducive to controlling the density of the product obtained. However, this is an essential feature for evaluating the quality of the product obtained.

[0006] The present invention is intended to provide a technical solution to the above-mentioned shortcomings. More particularly, in at least one embodiment, the proposed technology relates to a facility for melting a raw material composition suitable for obtaining glass wool, rock wool, woven glass fiber and / or flat glass or hollow glassware, the facility comprising a melting chamber provided with at least one inlet, at least one outlet and at least one submerged burner adjacent to the outlet, characterized in that the facility comprises an "anti-sloshing" barrier, the "anti-sloshing" barrier being arranged between the proximal burner and the furnace outlet at a certain horizontal distance (dX) from the proximal burner, the horizontal distance (dX) being 20% ​​to 80% of the total horizontal distance (dTot) separating the proximal burner from the outlet, preferably 30% to 70%, more preferably 40% to 60%, even more preferably 45% to 55% of the total horizontal distance separating the proximal burner from the outlet.

[0007] Throughout the text, the expression "horizontal distance" refers to the distance measured on a horizontal plane between the orthogonal projections (on this horizontal plane) of each specified element. Thus, the distance separating the furnace outlet from its proximal burner, i.e. the burner closest to it (also referred to herein as the "last burner") is measured.

[0008] The invention is based on a novel and inventive concept involving the use of an anti-sloshing barrier at a selected distance between the "last" burner and the furnace outlet. "Barrier" means a device in the form of an obstacle or a set of obstacles to the local flow of the glass bath, thereby making it possible to reduce sloshing without necessarily eliminating it.

[0009] In this context, it should be noted that, although problems with furnace load instabilities have been observed in the past, it was not possible to observe in real time what was happening inside the furnace. In order to better understand the causes of this instability, and as described in detail in the description, the inventors have therefore set up and implemented a comprehensive research program aimed at reproducing in the laboratory the fluid dynamic phenomena existing inside industrial furnaces, so as to be able to identify and better understand them. This research program has revealed in particular the phenomenon known as "sloshing" that occurs inside the glass bath, and has made it possible to observe the advantageous reduction of this sloshing caused by the use of an "anti-sloshing" barrier according to the invention. The term "sloshing" (and by extension "anti-sloshing" to describe the barrier according to the invention) has been chosen due to the phenomenon that occurs inside the glass bath, and is more particularly illustrated by the accompanying drawings of an experimental facility with said barrier that will be described subsequently. By definition, the term "sloshing" means sloshing, that is to say the movement of a body that moves alternately in one direction and in another (Dictionnaire de la langue Le Petit Robert).

[0010] In particular, the inventors were able to observe that the reduction of sloshing is better when the barrier is arranged at an intermediate distance between the last burner and the outlet (i.e. dX=50% dTot), and that the reduction of sloshing tends to decrease as the barrier moves away from this intermediate position. In particular, an arrangement at less than 20% of the horizontal distance separating this last burner from the outlet is considered unacceptable, firstly because it promotes the creation of strong current loops in the glass bath - which reduces the residence time of the glass in the furnace and increases the risk of unmelted material, and secondly because such an arrangement close to the burners leads to an increase in heat losses and corrosion phenomena at the barrier. On the contrary, positioning the anti-sloshing barrier close to the furnace outlet leads to the formation of undesirable glass blockages, in particular when the barrier cools from outside the furnace.

[0011] According to a particular embodiment, an anti-sloshing barrier is arranged near the surface of the molten glass pool so as to form an obstacle capable of at least limiting the phenomenon known as sloshing.

[0012] Advantageously, the anti-sloshing barrier is configured to limit or even eliminate said sloshing phenomena occurring in the molten glass bath, in particular but not exclusively on the surface of said bath.

[0013] According to a particular embodiment, the anti-sloshing barrier is configured to leave an atmospheric connection between upstream and downstream of the barrier. Through this connection, the atmospheric pressure upstream and downstream of the anti-sloshing barrier is the same.

[0014] Advantageously, the anti-sloshing barrier according to the invention is arranged on the surface of the glass bath so as to form an obstacle, in particular to the flow present on the surface of said bath, so as to stabilize the surface thereof. The anti-sloshing barrier is preferably partially immersed in the glass bath.

[0015] According to a particular embodiment, the anti-sloshing barrier comprises a first part arranged vertically so as to be flush below the theoretical level of the molten glass bath.

[0016] According to a particular embodiment, in which the liquid glass leaves the furnace by overflow, this theoretical level of the glass bath corresponds to the height of the furnace outlet and is more precisely defined by a theoretical horizontal plane passing through this outlet. As described in detail in the specification, experimental tests conducted by the inventors have shown that an anti-slosh barrier positioned in this manner is more effective.

[0017] According to a particular embodiment, the anti-sloshing barrier comprises a second part which is arranged vertically so as to be flush above the theoretical level of the molten glass bath.

[0018] Taking into account the relatively high viscosity of the molten glass pool and as described in detail in the description, experimental tests carried out by the inventors have shown that the use of an anti-sloshing barrier - at least one component of which is flush above the surface of the molten glass pool (in addition to another component that is flush below) - makes it possible to limit the surface overflow of the molten glass pool and therefore limit the sloshing phenomenon.

[0019] According to a specific embodiment, the anti-sloshing barrier is vertically arranged above a height equal to 60% of the theoretical liquid level of the molten glass bath, preferably above a height equal to 70%, more preferably above 80% of the theoretical liquid level of the molten glass bath.

[0020] According to a particular embodiment, said first part of the anti-slosh barrier comprises a first rectilinear element extending across the width of the melting chamber.

[0021] According to a particular embodiment, said second part of the anti-slosh barrier comprises a second rectilinear element arranged above said first rectilinear element in a direction parallel to the first rectilinear element.

[0022] In other words, the anti-sloshing barrier is arranged so that the theoretical horizontal mid-plane between the two linear elements substantially coincides with the theoretical level of the glass bath. In this configuration, the first linear element is thus completely submerged, while the second linear element is arranged above the glass bath, acting as a barrier to any surface waves.

[0023] According to a particular embodiment, the first linear element and the second linear element are spaced apart from each other by a distance of 0.1 to 16 mm, preferably 2 to 12 mm, preferably 4 to 8 mm.

[0024] In practice, due to the cooling of the liquid glass at its interface with the anti-sloshing barrier, a devitrified material (crystallized glass) is locally formed. The space between the two rectilinear elements forming the barrier is thus blocked by the devitrified material, which helps to form an obstacle to the flow of the molten glass pool, while reducing the contact surface of the rectilinear elements with the molten glass pool, thereby making it possible to reduce the associated heat losses. Although the thickness of the devitrified material formed can vary according to several parameters that can be controlled by those skilled in the art (nature of the molten glass pool, dimensions of the barrier, etc.), the preferred range of values ​​claimed for the spacing between the rectilinear elements provides the best compromise between forming an effective obstacle to the flow of the molten glass pool and limiting heat losses.

[0025] According to a particular embodiment, said first rectilinear element and / or said second rectilinear element have a tubular cross-section.

[0026] The advantage of using a tubular cross-section is that the stresses generated by the molten glass bath are distributed satisfactorily over the relevant rectilinear elements.

[0027] According to a particular embodiment, said first rectilinear element and / or said second rectilinear element have a rectangular cross section.

[0028] The advantage of using a rectangular cross section is that it gives the linear element better resistance to thermal creep, especially when the linear element is very long.

[0029] According to a particular embodiment, the anti-slosh barrier has a depth to height ratio of less than 70%, preferably less than 50%, preferably less than 30%.

[0030] The inventors have thus observed that the anti-sloshing effect of a barrier increases as the ratio of its depth to height decreases.

[0031] According to a particular embodiment, the ratio of the height of the anti-sloshing barrier to the height of the molten glass pool is 10% to 60%, preferably 25% to 45%.

[0032] When the ratio of the height of the barrier to the height of the glass bath is less than 10%, the anti-sloshing effect is significantly reduced. Conversely, when the ratio is greater than 60%, the heat losses at the barrier tend to be too high. The best compromise between these two goals is achieved when the height ratio is 25% to 45%.

[0033] According to a particular embodiment, the anti-sloshing barrier consists of a bare metal wall through which passes an internal pipe system for cooling by a fluid, preferably water.

[0034] The invention also relates to a method for producing glass wool, rock wool, glass fabric fibers and / or flat glass or hollow glass containers, characterized in that the production method is carried out in such a facility with at least one step of melting the raw material composition.

[0035] The density of the produced mineral wool varies with the furnace load. Thus, the more stable this load is, the more uniform the density of the product obtained will be. Mineral wool, such as that obtained via the manufacturing method described above, has a relatively low standard deviation in its density, which limits the risk of obtaining a product that is lighter than desired and less insulating, or, on the contrary, a product that is more insulating but too heavy for the building it is intended to equip.

[0036] Other features and advantages of the invention will become apparent from the following description of specific embodiments given by way of illustrative and non-limiting example only, and from the accompanying drawings, in which:

[0037] [ Figure 1 ] Figure 1 is a schematic side view of an installation for melting a raw material composition according to a specific embodiment of the present invention,

[0038] [ Figure 2 ] Figure 2 is a schematic plan view of a facility for melting a raw material composition according to a specific embodiment of the present invention,

[0039] [ Figure 3 ] Figure 3 is a schematic side view of an anti-slosh barrier of a facility according to a specific embodiment of the present invention,

[0040] [ Figure 4 ] Figure 4 is a schematic side view of an experimental setup used by the inventors, with the barrier in a non-operational configuration,

[0041] [ Figure 5 ] Figure 5 yes Figure 4 Schematic side view of the experimental facility shown in , with the barrier in a non-operational configuration, depicting a later moment.

[0042] [ Figure 6 ] Figure 6 yes Figure 4 and 5 Schematic side view of the experimental facility shown in , with the barrier in the operational configuration.

[0043] The various components shown in the drawings are not necessarily shown to scale, with emphasis placed on illustrating the general operation of the present invention. In the various drawings, unless otherwise indicated, the same reference numerals represent similar or identical components.

[0044] Several specific embodiments of the present invention are given below. It should be understood that the present invention is by no means limited to these specific embodiments, and other embodiments are entirely possible.

[0045] Figure 1 and 2 The side ( Figure 1 ) and from above ( Figure 2 ) is a furnace (facility 1) with submerged burners according to a particular embodiment of the invention as observed in Figure 1 . Such a furnace 1 comprises two burners, including one burner close to the furnace outlet - marked 2 - which is the burner closest to the furnace outlet. These burners are immersed in a bath 3 of molten vitrifiable material, at a temperature of typically 1200° C. to 1700° C. Below the surface 6 of the molten material in the furnace, a worm 13 pushes a composition 5 of raw materials. A distributor 17 meters the preformed mixture and supplies it to a feed hopper 7, which in turn supplies the screw 13 rotating in a sleeve 4. The preformed mixture is introduced into the furnace via an orifice 12, also referred to as a feed point. The interior of the furnace 1 comprises at least one chamber 8, which contains a bath 3 of molten vitrifiable material. The formed mineral material leaves via an outlet 11 below the level of the molten material. The combustion gases escape via a chimney 16.

[0046] The installation 1 according to the invention comprises in particular an anti-sloshing barrier 10 arranged at the surface of the molten glass bath 3 in order to limit the sloshing effects occurring at the furnace outlet 11 .

[0047] For the purpose of spatial positioning, Figure 1 and / or 2 specifically show:

[0048] - the theoretical level of the glass bath 3 (Nth), which corresponds to the height of the outlet 11 (Hv),

[0049] - the height (Hx) of the lower end of the barrier 10,

[0050] - the height of the barrier 10 (Hb),

[0051] - the total horizontal distance (dTot) separating the proximal burner 2 from the outlet 11,

[0052] - The horizontal distance (dX) separating the proximal burner 2 from the barrier 10 .

[0053] according to Figure 1 and 2 , such a barrier 10 is formed by a single rectilinear block having a rectangular cross section and extending across the width of the furnace 1. Preferably, the barrier 10 extends across the entire width of the chamber 8 of the furnace 1. Such a barrier is arranged between the proximal burner 2 and the furnace outlet 11 at a horizontal distance (dX) from the proximal burner 2 equal to 40% of the total distance (dTot) separating the proximal burner 2 from the outlet 11, and is positioned at a height (Hx) greater than 80% of the height (Hv) of the glass bath 3, the height (HB) of the barrier also being equal to 35% of the height (Hv) of the glass bath.

[0054] The glass bath 3 is moved by convection currents generated therein by the burners, the shape of which depends directly on the geometry of the various furnace elements in contact with the glass, and on the positioning of the burners 2. For illustrative purposes, some of these convection currents are shown in FIG. Figures 1 to 3 The specific arrangement of the barrier 10 in the furnace makes it possible in particular to form an obstacle to the liquid flow present on the surface of the glass bath, thereby deflecting said liquid flow or at least reducing its intensity, thereby stabilizing the surface of the glass bath at the furnace outlet 11.

[0055] Figure 3 1 is a schematic side view of an anti-sloshing barrier 10 of a facility 1 according to a particular embodiment of the invention, wherein the barrier 10 is formed by two straight tubular elements 10A, 10B arranged vertically on either side of the theoretical surface (Nth) of the glass bath, or in other words, flush with the theoretical surface. Each of these tubular elements 10A, 10B consists of a bare metal wall cooled by an internal system of water pipes (also called "water jacket"). After the liquid glass cools at its interface with each of these tubular elements 10A, 10B, a layer of devitrified material 14 (crystallized glass) is formed to completely cover the barrier 10, in particular to fill the space (dE) located between the two tubular elements 10A, 10B, which in this example is 6 cm long. According to this particular embodiment, the height (Hb) of the barrier 10 corresponds to the distance separating the lower end of the first tubular element 10A (immersed) from the upper end of the second tubular element 10B (not immersed). The depth (e) of the barrier 10 corresponds to the diameter of these tubular elements. In this case, the ratio of the depth (e) of the barrier 10 to its height (Hb) is less than 50%.

[0056] As part of a research program aimed at obtaining a better understanding of the causes of instabilities occurring in submerged combustion furnaces, the inventors developed several experimental protocols in order to reproduce in the laboratory the fluid dynamic phenomena present in industrial furnaces. Figures 4 to 6 is a schematic side view of a first experimental model 20 developed for the purpose of these studies, comprising a chamber 21 containing water 22, which is intended to reproduce the behavior of a glass bath. A bubbler 23 is located in the center of the bottom of the chamber 21 in order to reproduce in the water 22 the entrainment effect caused by a burner immersed in the glass bath. A barrier 24 formed by a single rectangular block of substantially flat shape is arranged across the width of the chamber and is movable between a "non-operating" position, in which the barrier 21 is positioned just above the water bath 22 ( Figure 4 and Figure 5 ), in said "operating" position, the barrier 21 is immersed in the water 22 so that its upper end is flush with the surface of the stationary bath 22 ( Figure 6 ).

[0057] In the case of the first experimental model, a 5 cm high barrier was initially placed in the "non-operating" position, and the water level was set at 15 cm. Air was introduced via the bubbler 23 at 7 Nm 3 The water was injected at a flow rate of / h (standard cubic meters per hour). The sloshing behavior of the water was then captured by a camera. Figure 4 and 5 is a schematic depiction of a screenshot from a video recording. In particular, the movement of the bubble jet from left to right can be seen, reflecting the sloshing produced at the surface. Secondly, the barrier 24 is arranged in the "operating" position, the other parameters remaining the same. Figure 6 is a schematic depiction of a screenshot of a video recording taken immediately after the immersion of the barrier 24. In this figure it can be observed that the bubble jet in the center of the chamber 21 is stabilized, counteracting the sloshing effects.

[0058] The experiment was then repeated, varying the height (Hb) of the barrier 24, the air injection rate and the water level. The observed results are summarized in Table 1 below:

[0059]

[0060] [Table 1] Change in the amplitude of the surface wave after the barrier is submerged based on the water level, barrier height and injected air flow rate.

[0061] This first experimental model and the results obtained and presented in Table 1 highlight the effectiveness of the anti-sloshing barrier 21 in all the experimental conditions tested. Thus, either the sloshing is counteracted or the amplitude of the waves is acceptable since it corresponds to a surface agitated by strong bubbling without sloshing.

[0062] In the case of the second experimental model, liquid water was replaced by silicone oil having a viscosity of 500 centistokes (cSt) to better account for the high viscosity of the glass bath. Figure 3 The same configuration as shown, with the barrier 21 replaced by two straight tubes of 25 cm diameter, arranged one above the other and on either side of the liquid level of the stationary silicone oil bath. Similar to the first experimental model, a video camera was used to record the changes in the behavior of the silicone oil bath after the barrier was immersed. When the barrier was in the non-operating position, a significant sloshing could be clearly observed on the surface of the oil bath. In all the experimental conditions tested, switching the barrier to the "operating" configuration ended the sloshing effect, as detailed in Table 2 below.

[0063]

[0064] [Table 2] Observation (or absence) of sloshing based on barrier configuration, silicone oil level, and air flow rate.

[0065] This second experimental model and the results obtained and presented in Table 2 highlight the effectiveness of the anti-sloshing barrier 21 in all the experimental conditions tested, wherein sloshing was counteracted every time after the barrier was submerged.

Claims

1. A plant (1) for melting a raw material composition (5) suitable for obtaining glass wool, rock wool, woven glass fibers and / or flat glass or hollow glassware, the plant comprising a melting chamber (8) provided with at least one inlet (12), at least one outlet (11) and at least one submerged burner (2) adjacent to the outlet (11), characterized in that The facility (1) comprises an "anti-sway" barrier (10), which is arranged between the proximal burner (2) and the furnace outlet (11) at a certain horizontal distance (dX) from the proximal burner (2), and the horizontal distance (dX) is 20% to 80% of the total horizontal distance (dTot) separating the proximal burner (2) and the outlet (11), preferably 30% to 70% of the total horizontal distance (dTot) separating the proximal burner (2) and the outlet (11), more preferably 40% to 60%, and even more preferably 45% to 55%.

2. The facility (1) according to claim 1, characterized in that The anti-sloshing barrier (10) comprises a first part (10A) which is arranged vertically so as to be flush below a theoretical liquid level (Nth) of a molten glass pool.

3. The facility (1) according to claim 2, characterized in that The anti-sloshing barrier (10) comprises a second part (10B) which is arranged vertically so as to be flush above a theoretical liquid level (Nth) of the molten glass pool.

4. The installation (1) according to any one of claims 1 to 3, characterized in that The anti-sloshing barrier (10) is vertically arranged above a height (Hx) equal to 60% of the theoretical liquid level (Nth) height (Hv) of the molten glass pool, preferably above 70%, more preferably above 80% of the theoretical liquid level height (Hx) of the molten glass pool.

5. The installation (1) according to any one of claims 2 to 4, characterized in that The first component of the anti-slosh barrier (10) comprises a first linear element (10A) extending across the width of the melting chamber (8).

6. The installation (1) according to claim 5, characterized in that The second component of the anti-slosh barrier (10) comprises a second linear element (10B) which is arranged above the first linear element (10A) in a direction parallel to the first linear element (10A).

7. The installation (1) according to claim 6, characterized in that The first linear element (10A) and the second linear element (10B) are spaced apart from each other by a distance (dE) of 0.1 to 16 mm, preferably 2 to 12 mm, preferably 4 to 8 mm.

8. Installation (1) according to any one of claims 5 to 7, characterized in that The first linear element (10A) and / or the second linear element (10B) has a tubular cross-section.

9. Installation (1) according to any one of claims 5 to 7, characterized in that The first linear element (10A) and / or the second linear element (10B) has a rectangular cross-section.

10. Installation (1) according to any one of claims 1 to 9, characterized in that The anti-slosh barrier (10) has a depth (e) to height (HB) ratio of less than 70%, preferably less than 50%, preferably less than 30%.

11. Installation (1) according to any one of claims 1 to 10, characterized in that The ratio of the height (HB) of the anti-sloshing barrier (10) to the height (Hv) of the molten glass pool is 10% to 60%, preferably 25% to 45%.

12. Installation (1) according to any one of claims 1 to 11, characterised in that The anti-slosh barrier (10) consists of a bare metal wall through which passes an internal pipe system for cooling by a fluid, preferably water.

13. Installation (1) according to any one of claims 1 to 12, characterised in that The anti-sloshing barrier (10) is arranged near the surface of the molten glass pool so as to form an obstacle capable of at least limiting (or even counteracting) the phenomenon known as sloshing.

14. Installation (1) according to any one of claims 1 to 13, characterised in that The anti-sloshing barrier (10) is configured to leave an atmospheric connection between upstream and downstream of the barrier.

15. A method for producing glass wool, rock wool, glass fabric fibers and / or flat glass or hollow glassware, characterized in that The manufacturing method comprises carrying out at least one step of melting the raw material composition (5) in a facility (1) according to one of claims 1 to 14.

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