HIGH-EFFICIENCY FURNACE

Abstract

An installation for melting a composition of raw materials, suitable for obtaining glass wool, textile glass yarns and/or flat glass, includes a melting chamber equipped with at least one submerged burner, wherein the melting chamber is defined by side walls made of refractory material and a bare metal bottom traversed by a network of pipes adapted for the circulation of a cooling fluid.

Claims

1. An installation for melting a composition of raw materials, suitable for obtaining glass wool, textile glass yarns and/or flat glass, which comprises a melting chamber equipped with at least one submerged burner, wherein the melting chamber is defined by side walls made of refractory material in accordance with the ISO/R836 or AFNOR NF B 40-001 standards and a bare metal bottom to which said at least one submerged burner is attached and which is traversed by a network of pipes adapted for the circulation of a cooling fluid.

2. The installation according to claim 1, wherein said metal bottom is removably attached to said side walls.

3. The installation according to claim 1, wherein said bottom comprises at least one central portion adapted to form the a lower surface of the melting chamber, and a connecting flange adapted to abut flat below said side walls.

4. The installation according to claim 3, wherein said connecting flange forms a shoulder with said at least one central portion.

5. The installation according to claim 3, wherein said bottom comprises a circumferential portion which is complementary in shape to the perimeter of said central portion and is adapted to serve as a base for said side walls, and to be flush with said connecting flange on the other.

6. The installation according to claim 5, wherein said circumferential portion is adapted to be attached to said connecting flange in a removable manner.

7. The installation according to claim 5, comprising at least one combustion gas seal arranged at the interface between said circumferential portion and said connecting flange.

8. The installation according to claim 1, wherein said bare metal bottom is adapted to be traversed by at least one submerged burner and/or a boiler, which are removably attached to the bottom.

9. The installation according to claim 1, wherein said side walls made of refractory material are at least partly covered on their periphery with a metal mantle traversed by a network of pipes adapted for the circulation of a cooling fluid.

10. The installation according to claim 1, wherein said at least one submerged burner comprises an injector block equipped with a combustion gas distribution network and a plurality of injectors.

11. A method comprising melting a composition of vitrifiable raw materials with an installation according to claim 1.

12. The installation according to claim 1, wherein the melting chamber is cylindrical in shape.

13. The installation according to claim 1, wherein the cooling fluid is water.

14. The installation according to claim 6, wherein said circumferential portion is adapted to be attached to said connecting flange by a screw-nut attachment.

15. The installation according to claim 9, wherein said cooling fluid is water.

Description

[0048] Further features and advantages of the invention will become apparent from the following description of particular embodiments, given merely as illustrative and non-limiting examples, and the appended figures, for which:

[0049] FIG. 1 is a schematic cross-sectional exploded view of an installation for melting a composition of raw materials, according to a particular embodiment of the invention,

[0050] FIG. 2 is an enlarged view of the lower part of an installation such as the one shown in FIG. 1, in exploded view.

[0051] FIG. 3 is an enlarged view of the lower part of an installation such as the one shown in FIG. 1, when the bottom 3 is arranged at the bottom of the furnace.

[0052] The various elements illustrated in the figures are not necessarily shown to actual scale, the emphasis being more on representing the general operation of the invention. In the various figures, unless otherwise indicated, reference numbers that are identical represent similar or identical elements.

[0053] It is further understood that the present invention is in no way limited by the particular embodiments described and/or depicted, and that other embodiments are perfectly possible.

[0054] FIGS. 1 to 3 represent all or part of an installation 1 (furnace) for melting a composition of raw materials, and are intended to illustrate its general operation. Such an installation 1 is suitable for obtaining glass wool and/or glass textile yarns. It comprises a cylindrical melting chamber 2 oriented along a vertical axis, and is delimited by side walls 4 and a vault made of refractory materials and a bare metal bottom 5, of the water-jacket type, through which a submerged burner 3 passes.

[0055] For clarity and simplicity, the furnace 1 shown in FIGS. 1 through 3 comprises only a single burner 3, and no boiler. It goes without saying that the scope of the invention is in no way limited by the number of burners/boilers used in the furnace.

[0056] The furnace 1 comprises a raw material intake 8 at the bottom, located below the theoretical level of the molten raw material bath, also referred to as the glass melt in this description. The raw materials are generally fed into the melting chamber 2 by means of a feeder (not shown).

[0057] Once in the glass melt, the raw materials are melted by means of the submerged burner 3, also arranged below the level of the glass melt. In FIGS. 1 and 2, this burner 3 is presented in the form of an injector block equipped with a combustion gas distribution network and a plurality of injectors. The invention is not, however, limited to the implementation of such a type of burner which may, according to alternative embodiments, be, for example, ring-shaped and/or of the single-injector type.

[0058] The gases resulting from the combustion of the raw materials are recovered via an exhaust chimney 9 arranged in the upper part of the combustion chamber 2. The molten mixture is discharged from the furnace 1 via a weir 10 for a subsequent step of fiberizing glass wool or spinning glass textile yarns. An emergency outlet 11, located at the base of the melting chamber 2 or alternatively in the bottom, allows the furnace to be purged if necessary.

[0059] FIGS. 2 and 3 show an enlargement of the lower part of the plant, and in particular of the connections between the different components of the bottom 5 and the side walls 4 made of refractory material.

[0060] According to the particular embodiment illustrated in FIGS. 2 and 3, the bottom 5 comprises in particular a central portion 5a adapted to form the lower surface of the melting chamber 2 or in other words, to form the bottom of the glass melt tank. This central portion 5a is in particular crossed by the burner 3, secured on its lower part by means of screws. A metallic circumferential portion 5c of the bottom 3 serves as a base for the side walls 4 which rest on it in a planar manner, while being integral with an external metallic structure of the furnace 1 (not shown). This circumferential portion 5c is also complementary in shape to the periphery of the central portion 5a of the base 5, so that this central portion 5a, when inserted at the base of the tank 2, closes off the central opening formed by the side walls 4, thus forming a hermetic tank bottom, at least for the passage of the molten glass, as illustrated in FIG. 3. A connecting flange 5b forms a shoulder at the base of the central portion 5a and rests flat against the lower part of the circumferential portion 5c, thus reinforcing the gas-tightness of the tank bottom, in particular by means of a seal (not shown) arranged at the interface between these two elements. According to the particular embodiment shown in FIGS. 1 to 3, the connecting flange 5b is removably attached to the circumferential portion 5c, by means of a plurality of screws.

[0061] According to an alternative embodiment, not shown in the figures, the bottom 3 does not comprise a circumferential portion 3c. The bottom 3 is then attached directly to the lower part of the side walls 4, by planar contact of the connecting flange 5b with the base of the side walls, or with an intermediate plate acting as their base. Such an attachment can alternatively be reversible or irreversible.

[0062] According to an alternative embodiment, not shown in the figures, the bottom 3 comprises a circumferential portion 3c, but the latter is removably attached to the side walls 4, for example by means of a plate acting as a base for these side walls 4.

[0063] In order to evaluate the role played by the materials constituting respectively the bottom 3 and the side walls 4, on the improvement of the energy performances of the furnace 1, a test is simulated by computer via a thermal model for a furnace having a melter of 1 m.sup.2, for 1 m of soda-lime glass melt at 1200° C. The surface of glass contact walls is 5 m.sup.2.

[0064] For a first sample, all the walls of the furnace, including the bottom, are water-jacketed bare metal. The energy losses at the glass contact walls are then estimated at 500 kW.

[0065] In a second sample, the entire furnace wall, including the bottom, is made of refractory materials. The energy losses at the glass contact walls are then estimated at 50 kW.

[0066] It is therefore observed that the thermal losses at the walls in contact with glass are ten times higher in the case of water-jacketed walls, compared to walls made of refractory materials.

[0067] For a third sample, representative of a furnace according to the invention, the side walls are made of refractory materials, while the bottom is water-jacketed bare metal. The energy losses at the glass contact walls are then estimated at 140 kW.

[0068] Compared to the first sample, the use of the third sample, according to the claimed invention, makes it possible to limit the thermal losses and to increase significantly the energy efficiency of the furnace, for an acceptable life time, the water-jacketed bottoms being much more resistant to corrosion by glass than the refractory bottoms.