Glass melting furnace with submerged burner, comprising an Anti-slosh barrier

Abstract

The invention relates to a facility (1) for melting a composition of raw materials (5) suitable for obtaining glass wool, rock wool, textile glass fibres and / or flat glass or hollow glassware, the facility comprising a melting chamber (8) provided with at least one inlet (12), at least one outlet (11) and at least one submerged burner (2) proximal to the outlet (11) The facility comprises a barrier (10) arranged between the proximal burner and the outlet, which barrier is intended to limit the sloshing movement of the glass, in particular at the surface of the bath.

Description

Description GLASS MELTING FURNACE WITH SUBMERGED BURNER INCLUDING AN ANTI-SLOLLING BARRIER

[0001] The present invention relates to an installation for the fusion of a composition of raw materials suitable for obtaining glass and / or rock fibers, of the thermal or sound insulation mineral wool type, of so-called reinforcing textile glass yarns. , and / or flat glass.

[0002] In this text, these “raw materials” include first of all vitrifiable materials which make it possible to obtain the targeted mineral composition of the glass or rock or silicate type. These vitrifiable materials include silica sand, but also all additives (sodium carbonate, limestone, dolomite, alumina, etc.), and any type of cullet. In the description, the expressions “liquid glass” and “glass bath” designate the product of the fusion of these vitrifiable materials. Also included in the raw material compositions are recyclable materials containing (organic) combustible elements such as, for example, sized mineral fiber waste, with binder (of the type used in thermal or acoustic insulation or those used in the reinforcement of plastic material), coming from production sites (factories) of said fibers, construction sites (construction or deconstruction) and / or recycling sectors making it possible to recover such fibers in final products, whether or not they are used. Such mineral fibers may in particular consist of glass and / or rock. We then speak respectively of glass wool and rock wool. Also included are laminated glazing with polyvinyl butyral type polymer sheets such as windshields, glass bottles (household cullet), or any type of “composite” material combining glass and plastic materials such as certain bottles. “Glass-metal composites or metal compounds” such as glazing coated with layers of enamel, layers of metal and / or different connector elements are also recyclable. Also included in the raw materials are all forms of biomass, that is to say organic matter of plant, animal, bacterial or fungal origin, usable mainly as fuel, but also playing the role of raw material influencing the composition of the vitrifiable material manufactured since its ash content is generally not zero.

[0003] The invention relates more particularly to an installation (furnace) known as “with submerged burner(s)”. Such burners are generally powered by a mixture of oxygen and gas, or a mixture of air and gas, and generally arranged so as to be flush with the bottom of the melting chamber, so that the Flame develops within the mass of raw materials during liquefaction. These burners can be such that their gas supply conduits are flush with the wall they pass through. According to certain embodiments, it is possible to choose to inject only gases resulting from combustion, the latter then being carried out outside the fusion chamber itself.

[0004] In known manner, the melting chamber of such an installation comprises in the lower part a raw materials supply port, or submerged type inlet, located below the theoretical level of the bath of molten raw materials, also called bath of glass throughout the description. The raw materials are generally brought into the melting chamber by means of a feeder comprising a body with a sheath and a mechanical system for driving the raw materials, in the form of a piston or an endless screw . The molten mixture then leaves the oven via a dedicated outlet, for a subsequent step of fiberizing glass wool or spinning textile glass yarns. The inlet(s) and outlet(s) of the furnace are adapted to allow the introduction of raw materials on the one hand, and simultaneously, the extraction of molten material on the other hand, so that throughout the process melting, the level of the glass bath remains substantially constant. We call drawn the quantity of molten material leaving the furnace, per unit of time (for example, in tons per day).

[0005] A disadvantage of known technology lies in the variations observed by the inventors of this drawing, over more or less short periods of time. Such variations in output flow, also called instabilities in the rest of the text, harm the quality of the products obtained after forming. Indeed, variations in instantaneous glass pulls cause instability in the fibering, which generates more waste. Other disadvantage, the quantity of fibers created at a given moment also varies, which affects the density control of the product obtained. However, this is a key characteristic for evaluating the quality of the products obtained.

[0006] The invention aims to provide a technical solution to the drawbacks described above. More particularly, in at least one embodiment, the proposed technique relates to an installation for the fusion of a composition of raw materials, suitable for obtaining glass wool, rock wool, textile glass yarns and / or flat or hollow glass, which comprises a melting chamber equipped with at least one inlet, at least one outlet and at least one submerged type burner proximal to said outlet, characterized in that said installation comprises a so-called “anti-sloshing” barrier which is arranged, between said proximal burner and said oven outlet, at a horizontal distance (dX) from said proximal burner of between 20% and 80% of the total horizontal distance (dTot) separating said proximal burner of said outlet, preferably between 30% and 70%, more preferably between 40 and 60%, even more preferably between 45% and 55% of the total horizontal distance separating said proximal burner from said outlet.

[0007] Throughout the text, the expression “horizontal distance” refers to a distance measured, along a horizontal plane, between the orthogonal projections (on this horizontal plane) of each of the designated elements. This is how the distance separating an outlet of the oven from its proximal burner is measured, that is to say the burner which is closest to it, also called “last burner” in this text.

[0008] The invention is based on a new and inventive concept consisting of implementing an anti-sloshing barrier at a chosen distance between the “last” burner and the oven outlet. By “barrier”, we mean a device in the form of an obstacle or a set of obstacles to the local flow of the glass bath, thus making it possible to reduce the sloshing, without necessarily eliminating it.

[0009] In this context, it should be noted that although problems with instability of the firing of a furnace could be observed in the past, it was impossible to observe in real time what was happening inside the furnace. an oven. In order to to better understand the causes of these instabilities, and as detailed in the description, the inventors have thus set up and conducted a complete research program aimed at reproducing in the laboratory the hydrodynamic phenomena present within an industrial oven, in order to be able to identify them and understand them better. This research program notably made it possible to highlight a phenomenon known as “sloshing” generated within the glass bath, and to note the advantageous reduction of this sloshing induced by the implementation of a so-called “anti-sloshing” barrier. » according to the invention. The term “ballooning” (and by extension that of “anti-ballooning” to qualify the barrier according to the invention) was chosen because of the phenomenon generated within the glass bath and more particularly illustrated by the figures of the experimental installation with said barrier which will be described later. By definition, the term “ballotment” in fact designates the movement of a body which sways, that is to say which goes alternately in one direction and the other (Dictionary of the French language, Le Petit Robert).

[0010] The inventors were notably able to note that the reduction in sloshing is better when said barrier is arranged halfway (i.e. dX = 50% dTot) between the last burner and the outlet, and tends to decrease when said barrier moves away from this middle position. In particular, an arrangement less than 20% of the horizontal distance separating this last burner from said outlet is considered prohibitive, firstly because it favors the generation of a strong current belt within the glass bath - which reduces the residence time of the glass in the oven and increases the risk of unmelts - and secondly because such an arrangement close to the burner causes an increase in the phenomena of thermal loss and corrosion at the level of the barrier. Conversely, positioning the anti-sloshing barrier near the oven outlet could cause the unwanted formation of a glass plug, in particular when the barrier is subject to cooling from the outside. from the oven.

[0011] According to a particular embodiment, the anti-sloshing barrier is arranged in the vicinity of the surface of the glass bath to form an obstacle capable of at least limiting the so-called sloshing phenomenon.

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

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

[0014] Advantageously, the anti-sloshing barrier according to the invention is arranged on the surface of the glass bath to form an obstacle, in particular to the currents present on the surface of said bath in order to stabilize the surface. Preferably, the anti-sloshing barrier is partially immersed in the glass bath.

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

[0016] According to a particular embodiment in which the liquid glass outlet is implemented by overflow, this theoretical level of the glass bath corresponds to the height of the oven outlet, and more precisely is defined by the theoretical horizontal plane crossing this outlet . As detailed in the description, the experimental tests carried out by the inventors demonstrated that an anti-swaying barrier positioned in this way was more effective.

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

[0018] Taking into account the relatively high viscosity of the glass bath, and as detailed in the description, the experimental tests carried out by the inventors made it possible to demonstrate that the implementation of an anti-sloshing barrier of which at least one component is flush with the -above the surface of the glass bath, in addition to another part flush below, makes it possible to limit overflows on the surface of the latter, and therefore the phenomenon of sloshing.

[0019] According to a particular embodiment, said anti-swaying barrier is arranged vertically above a height equal to 60% of the height of the theoretical level of the glass bath, preferably 70%, more preferably 80% of the height of the level theory of the glass bath.

[0020] According to a particular embodiment, said first part of the anti-sloshing barrier comprises a first rectilinear element which extends along the width of the melting tank.

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

[0022] In other words, the anti-sloshing barrier is arranged so that the theoretical horizontal median plane between the two rectilinear elements is substantially coincident with the theoretical level of the glass bath. According to this configuration, the first rectilinear element is thus completely immersed, while the second rectilinear element is arranged above the glass bath, providing a barrier to any waves on the surface.

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

[0024] In practice, a devitrified (frozen glass) is formed locally following the cooling of the liquid glass at its interface with the anti-sloshing barrier. The space provided between the two rectilinear elements forming this barrier is thus sealed by this devitrified which contributes to obstructing the flow of the glass bath, while making it possible to reduce the contact surface of the rectilinear elements with the glass bath, and thus reduce the associated heat losses. Even if the thickness of devitrified formed can vary depending on several parameters (nature of the glass bath, dimensioning of the barrier, etc.) that a person skilled in the art has mastered, the preferred value ranges claimed for this spacing between the elements rectilinear offer an optimal compromise between on the one hand, the formation of an effective obstacle to the flow of the glass bath and on the other hand, the limitation of heat losses.

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

[0026] The implementation of a tubular shaped section has the advantage of allowing a satisfactory distribution of the stresses generated by the glass bath on the rectilinear element in question.

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

[0028] The use of a rectangular section has the advantage of giving the rectilinear element better resistance to hot creep, in particular when the latter has a significant length.

[0029] According to a particular embodiment, said anti-sloshing 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 the barrier increases when the ratio of its depth to its height decreases.

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

[0032] When this 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 this ratio is greater than 60%, heat losses at the barrier tend to be too great. The best compromise between these two objectives is obtained when this height ratio is between 25% and 45%.

[0033] According to a particular embodiment, said anti-sloshing barrier is made up of bare metal walls which are traversed by a system of internal pipes for cooling by fluid, preferably water.

[0034] The invention also relates to a process for manufacturing glass wool, rock wool, textile glass threads and / or flat or hollow glass, characterized in that said manufacturing process implements at least one step of melting a composition of raw materials in such an installation.

[0035] The density of the mineral wool produced varies with the length of time it is fired from the oven. Also, the more stable this pull is, the more homogeneous the density of the product obtained. A mineral wool such as that obtained via the manufacturing process described above therefore has a relatively lower standard deviation in its density, which limits the risks of obtaining a lighter and less insulating product than desired, or on the contrary more insulating but too heavy for the receiving building.

[0036] Other characteristics and advantages of the invention will appear on reading the following description of particular embodiments, given as simple illustrative and non-limiting examples, and the appended figures, for which:

[0037] [Fig. 1] Figure 1 is a schematic side view of an installation for melting a composition of raw materials, according to a particular embodiment of the invention,

[0038] [Fig. 2] Figure 2 is a schematic top view of an installation for melting a composition of raw materials, according to a particular embodiment of the invention,

[0039] [Fig. 3] Figure 3 is a schematic side view of an anti-sway barrier of an installation according to a particular embodiment of the invention,

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

[0041] [Fig. 5] Figure 5 is a schematic side view of the experimental setup shown in Figure 4, with a barrier in non-operational configuration, captured at an offset time.

[0042] [Fig. 6] Figure 6 is a schematic side view of the experimental installation illustrated in Figures 4 and 5, with a barrier in operational configuration.

[0043] The different elements illustrated by the figures are not necessarily represented on a real scale, the emphasis being placed more on the representation of the general functioning of the invention. In the various figures, unless otherwise indicated, reference numbers which are identical represent similar or identical elements.

[0044] Several particular embodiments of the invention are presented below. It is understood that the present invention is in no way limited by these particular embodiments and that other embodiments can perfectly be implemented.

[0045] Figures 1 and 2 schematically represent an oven (installation 1) with submerged burners according to a particular embodiment of the invention, seen respectively from the side (Figure 1) and from above (Figure 2). Such an oven 1 comprises two burners, including a burner proximal to the oven outlet - referenced 2 - which is the burner closest to the oven outlet. These burners are immersed in a bath 3 of vitrifiable materials being melted, at a temperature generally between 1200°C and 1700°C. An endless screw 13 pushes a composition 5 of raw material under the surface 6 of the material being melted in the oven. A distributor 17 doses and supplies pre-constituted mixture to a supply hopper 7, which then supplies the endless screw 13 rotating in a sheath 4. The pre-constituted mixture is introduced into the oven through the orifice 12, also called loading point . The interior of the oven 1 comprises at least one tank 8 containing the bath 3 of vitrifiable material being melted. The mineral material formed exits through outlet 11 below the level of the molten materials. The combustion gases escape through a chimney 16.

[0046] An installation 1 according to the invention notably comprises an anti-sloshing barrier 10 arranged at the surface of the glass bath 3, in order to limit the effects of sloshing caused at the outlet 11 of the oven.

[0047] For spatial identification purposes, the following are illustrated in Figures 1 and / or 2: - the theoretical level (Nth) of the glass bath 3, which corresponds to the height (Hv) of the outlet 11, - the height (Hx) of the lower end of barrier 10, - the height (Hb) of barrier 10, - the total horizontal distance (dTot) separating the proximal burner 2 from the outlet 11, - the horizontal distance (dX) separating the proximal burner 2 from the barrier 10.

[0048] According to the particular and non-limiting embodiment illustrated in Figures 1 and 2, such a barrier 10 is formed from a single rectilinear block, of rectangular section, and which extends along the width of the oven 1. Preferably, the barrier 10 extends over the entire width of the tank 8 of the oven 1. Such a barrier is arranged, between the proximal burner 2 and the outlet of the oven 11, at a horizontal distance (dX) from the proximal burner 2 equal to 40% of the total distance (dTot) separating said proximal burner 2 from the outlet 11, and positioned at a height (Hx) greater than 80% of the height (Hv) of the glass bath 3, the height of the barrier (HB) being also equal to 35% of the height (Hv) of the glass bath.

[0049] The glass bath 3 is moved by convection currents generated within it by the burners, and whose shape depends directly on the geometry of the different elements of the furnace in contact with the glass, as well as the positioning of these burners 2. A For purposes of illustration, some of these convection currents are represented in Figures 1 to 3 by dedicated arrows. The specific arrangement of the barrier 10 in the oven makes it possible in particular to form an obstacle to the currents present on the surface of the glass bath, so as to deflect the latter or at least to attenuate their intensity, thus stabilizing the surface of the bath glass at oven outlet 11.

[0050] Figure 3 is a schematic side view of an anti-sloshing barrier 10 of an installation 1 according to a particular embodiment of the invention in which said barrier 10 is formed of two rectilinear elements 10A, 10B of tubular shape, which are arranged vertically on either side of the theoretical surface of the glass bath (Nth) or in other words, flush with the latter. Each of these tubular elements 10A, 10B is made up of bare metal walls cooled by a system of internal water pipes, also designated by the English expression “water-jacket”. Following the cooling of the liquid glass at its interface with each of these tubular elements 10A, 10B, a layer of devitrified 14 (frozen glass) is formed to completely cover the barrier 10, in particular filling the space (dE) arranged between the two tubular elements 10A, 10B, with a length of 6 cm in this example. 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 (submerged) from the upper end of the second tubular element 10B (emerged). The depth (e) of the barrier 10 corresponds to the diameter of these tubular elements. In the present case, the ratio of the depth (e) of the barrier 10 to its height (Hb) is less than 50%.

[0051] As part of a research program aimed at better understanding the causes of instabilities generated within a submerged burner furnace, several experimental protocols were developed by the inventors in order to reproduce in the laboratory the hydrodynamic phenomena present within an industrial oven. Figures 4 to 6 are schematic side views of a first experimental model 20 developed for these research purposes, which includes a tank 21 containing water 22 intended to reproduce the behavior of the glass bath. A bubbler 23 is centered at the bottom of the tank 21, so as to reproduce in the water 22 the entrainment effect caused by the burners immersed within the glass bath. A barrier 24 formed from a single rectangular block of substantially flat shape is arranged along the width of the tank, and is movable between a so-called “non-operational” position in which this barrier 21 is positioned well above the bath. water 22 (Figures 4 and 5), and a so-called “operational” position in which this barrier 21 is immersed in the water 22, so that its upper end is at the level of the surface of the bath 22 at rest (Figure 6) .

[0052] As part of this first experimental model, a 5 cm high barrier is initially placed in the “non-operational” position, while the water level is set at 15 cm. Air is injected via the bubbler 23 at a flow rate of 7 Nm3 / h (Normal cubic meter per hour). The sloshing behavior of the water is then captured using a video camera. As such, Figures 4 and 5 correspond schematically to screenshots of the video recording made. In particular, we can observe the movement from left to right of the jet of bubbles, witness to the sloshing generated on the surface. Secondly, the barrier 24 is arranged in the “operational” position, the other parameters remaining unchanged. Figure 6 corresponds schematically to a screen capture of the video recording captured immediately after the immersion of the barrier 24. We observe a stabilization of the bubble jet in the center of the tank 21 and a cancellation of the sloshing effect.

[0053] The experiment is subsequently repeated by varying the height (Hb) of barrier 24, the air injection flow rate, and the water level. The observed results are recorded in [Tables 1] table 1 below.

[0054] [Tables 1] Variation in the amplitude of surface undulations after immersion of the barrier, depending on the water level, the height of the barrier, and the injected air flow.

[0055] 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 canceled or the amplitude of the undulations is acceptable, since it corresponds to that of a surface agitated by strong bubbling without sloshing.

[0056] As part of a second experimental model, liquid water is replaced by a silicone oil with a viscosity of 500 centistokes (cSt), in order to better take into account the high viscosity of a glass bath. At the same time, the barrier 21 is replaced by two rectilinear tubes of 25 cm in diameter, which are superimposed one above the other and arranged on either side of the level of the silicone oil bath at rest, in a configuration identical to that illustrated in Figure 3. Similar to the first model experimentally, the change in behavior of the silicone oil bath after immersion of the barrier is recorded using a video camera. When the barrier is in the non-operational position, significant sloshing is clearly observable on the surface of the oil bath. Tilting the barrier into the “operational” configuration puts an end to the sloshing effect, in all the experimental conditions tested, as detailed in [Tables 2] table 2 below.

[0057] [Tables 2] Observation (or not) of sloshing depending on the barrier configuration, silicone oil level and air flow.

[0058] 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, the sloshing being canceled each time following immersion of the barrier.

Claims

Demands 1. Installation (1) for melting a composition of raw materials (5), suitable for obtaining glass wool, rock wool, textile glass yarns and / or flat or hollow glass, comprising a melting chamber (8) equipped with at least one inlet (12), at least one outlet (11) and at least one submerged burner (2) proximal to said outlet (11), characterized in that said installation (1) comprises an "anti-sloshing" barrier (10) arranged, between said proximal burner (2) and said furnace outlet (11), at a horizontal distance (dX) from said proximal burner (2) of between 20% and 80% of the total horizontal distance (dTot) separating said proximal burner (2) from said outlet (11), preferably between 30% and 70%, more preferably between 40% and 60%, and even more preferably between 45% and 55% of the total horizontal distance (dTot) separating said proximal burner (2) from said outlet (11).

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

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

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

5. Installation (1) according to any one of claims 2 to 4, characterized in that said first part of the anti-sloshing barrier (10) comprises a first straight element (10A) which extends along the width of the melting tank (8).

6. Installation (1) according to claim 5, characterized in that said second part of the anti-sway barrier (10) comprises a second straight element (10B) arranged above said first straight element (10A), in a direction parallel to the latter.

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

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

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

10. Installation (1) according to any one of claims 1 to 9, characterized in that said anti-sway 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 said anti-sloshing barrier (10) to the height (Hv) of the glass bath is between 10% and 60%, preferably between 25% and 45%.

12. Installation (1) according to any one of claims 1 to 11, characterized in that said anti-sloshing barrier (10) consists of bare metal walls through which an internal fluid cooling system, preferably water, passes.

13. Installation (1) according to any one of claims 1 to 12, characterized in that said anti-sloshing barrier (10) is arranged in the vicinity of the surface of the glass bath to form an obstacle capable of at least limiting (or even canceling) a phenomenon known as sloshing.

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

15. A process for manufacturing glass wool, rock wool, textile glass yarns and / or flat or hollow glass, characterized in that said process of manufacturing implements at least one melting step of a raw material composition (5) in an installation (1) according to any one of claims 1 to 14.

Images