Glass melting plant

Abstract

A glass melting plant having a melting tank having end-fired heating, the melting tank having a feeding material inlet, an outlet for removing the molten glass, and a melt surface of at least 40 m.sup.2. At least one doghouse is laterally situated and is connected to the melting tank inlet for feeding material input. The doghouse has side walls that, together with the melting tank inlet, limit a feeding surface area, and has a feeding device. The doghouse has a roof with an end wall oriented toward the feeding device, which end wall encloses, with the roof, a gas compartment open toward the melting tank. To increase the specific melting performance with at least equal glass quality, the feeding surface of the doghouse is at least 8 m.sup.2 and, given a melt surface of at least 115 m.sup.2, is at least 7% of the melting tank melt surface.

Claims

1. A glass melting plant comprising: a melting tank having a width defined by two spaced apart end walls and a length defined by two spaced apart side walls, and end-fired heating provided by burners arranged in one of the end walls, the melting tank having an inlet for supplying feeding material, an outlet for removing molten glass, the inlet being arranged in a vicinity of the end wall with the burners and the outlet being arranged in a vicinity of the opposite end wall, and a melt surface area in the melting tank of at least 40 m.sup.2 and not greater than 200 m.sup.2, only one doghouse, the doghouse being laterally situated along one of the side walls and being connected to the inlet of the melting tank for the input of the feeding material, the doghouse having side walls that, together with the inlet of the melting tank, limit a feeding surface, and a feeding device, the doghouse having a roof that has an end wall oriented toward the feeding device, which end wall encloses, with the roof, a gas compartment that is open toward the melting tank, the feeding surface of the doghouse comprising an area of at least 8 m.sup.2 and, in case said melt surface area is greater than or equal to 115 m.sup.2, the feeding surface of the doghouse comprises an area of at least 7% and at most 25% of said melt surface area of the melting tank.

2. The glass melting plant as recited in claim 1, wherein the feeding surface area of the doghouse is, in case said melt surface area is greater than or equal to 90 m.sup.2, at least 9% of said melt surface area of the melting tank.

3. The glass melting plant as recited in claim 1, wherein the feeding surface of the doghouse is, in case said melt surface area is greater than or equal to 80 m.sup.2, at least 10% of said melt surface area of the melting tank.

4. The glass melting plant as recited in claim 1, wherein an apex of the roof of the doghouse has a distance from a block edge of the doghouse of at least 400 mm.

5. The glass melting plant as recited in claim 1, wherein an apex of the roof of the doghouse has a distance from a block edge of the doghouse of at least 500 mm.

6. The glass melting plant as recited in claim 1, wherein the doghouse has an electrical resistance heating unit.

7. The glass melting plant as recited in claim 6, wherein the doghouse has at least one electrode for the electrical resistance heating unit.

8. The glass melting plant as recited in claim 1, wherein the doghouse has at least one burner that is immersed in the melt from the floor, for heating.

9. A glass melting plant comprising: a melting tank having a width defined by two spaced apart end walls and a length defined by two spaced apart side walls, and end-fired heating provided by burners arranged in one of the end walls, the melting tank having an inlet for supplying feeding material, an outlet for removing molten glass, the inlet being arranged in a vicinity of the end wall with the burners and the outlet being arranged in a vicinity of the opposite end wall, and a melt surface area in the melting tank of at least 40 m.sup.2 and not greater than 200 m.sup.2, only one doghouse, the doghouse being laterally situated along one of the side walls and being connected to the inlet of the melting tank for the input of the feeding material, the doghouse having side walls that, together with the inlet of the melting tank, limit a feeding surface, and a feeding device, the doghouse having a roof that has an end wall oriented toward the feeding device, which end wall encloses, with the roof, a gas compartment that is open toward the melting tank, the feeding surface of the doghouse comprising an area of at least 8 m.sup.2 and, in case said melt surface area is greater than or equal to 115 m.sup.2, the feeding surface of the doghouse comprises an area of at least 7% and at most 25% of said melt surface area of the melting tank, the doghouse having an electrical heating resistance unit, wherein the electrical heating resistance unit comprises at least two electrodes which extend solely into the doghouse and transverse to a direction of transport of the charge, the two electrodes extending from opposite walls of the doghouse a same distance from the end wall and in line with and towards each other, but without touching each other.

10. The glass melting plant as recited in claim 9, wherein the at least two electrodes form an electrode pair.

11. The glass melting plant as recited in claim 10, wherein at least one additional electrode extends from a floor of the doghouse into the melt, and forms a floor electrode, and each floor electrode is assigned to an electrode pair extending laterally into the melt, and is situated at the same distance from the end wall as the electrode pair.

12. The glass melting plant as recited in claim 10, wherein a further laterally situated electrode pair has a distance that is at least 200 mm from a laterally situated electrode pair adjacent to the end wall of the doghouse.

13. The glass melting plant as recited in claim 9, wherein at least one additional electrode extends from a floor of the doghouse into the melt, and forms a floor electrode.

14. The glass melting plant as recited in claim 13, wherein a further laterally situated floor electrode has a distance that is at least 200 mm from a laterally situated floor electrode adjacent to the end wall of the doghouse.

15. The glass melting plant as recited in claim 9, wherein the at least two electrodes extend with a front segment into the glass melt completely within the doghouse, the length of the segment being at least 200 mm.

16. The glass melting plant as recited in claim 9, wherein the at least two electrodes adjacent to the end wall have a distance from the end wall of the doghouse that is at least 400 mm.

17. The glass melting plant as recited in claim 9, wherein the at least two electrodes adjacent to the end wall have a distance from the end wall of the doghouse that is at least 700 mm.

18. The glass melting plant as recited in claim 9, wherein each laterally inward-extending electrode pair has a distance from the block edge of the doghouse that is at least 200 mm.

19. The glass melting plant as recited in claim 9, wherein the at least two electrodes extend with a front segment into the glass melt, the length of the segment being at least 400 mm.

20. A glass melting plant comprising: a melting tank having end-fired heating, the melting tank having an inlet for supplying feeding material, an outlet for removing molten glass, and a melt surface area of at least 40 m.sup.2, at least one doghouse laterally situated and being connected to the inlet of the melting tank for the input of the feeding material, the doghouse having side walls that, together with the inlet of the melting tank, limit a feeding surface, and a feeding device, the doghouse having a roof and an end wall oriented toward the feeding device, which end wall encloses, with the roof, a gas compartment that is open toward the melting tank, the feeding surface area of the doghouse comprising at least 8 m.sup.2 and, in case said melt surface area is greater than or equal to 90 m.sup.2, the feeding surface of the doghouse comprises an area of at least 9% of said melt surface area of the melting tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the present invention is explained in more detail on the basis of exemplary embodiments shown in the Figures.

(2) FIG. 1 shows, in a top view, a melting tank having end-fired heating, having a doghouse of a first exemplary embodiment of a glass melting plant according to the present invention,

(3) FIG. 2 shows a section through the doghouse and the melting tank along the sectional plane A-A of the exemplary embodiment shown in FIG. 1,

(4) FIGS. 3 and 4 show a comparison of the coverage of the surface of the melt in the melting tank of a melting plant according to the present invention having a large feeding surface of the doghouse with a throughput performance of 300 t/d (FIG. 3) and having a conventional feeding surface of the doghouse with a throughput performance of 150 t/d (FIG. 4);

(5) FIG. 5 shows a second exemplary embodiment of a glass melting plant according to the present invention, in a top view,

(6) FIG. 6 shows the second exemplary embodiment of the glass melting plant according to FIG. 5 in a section along the sectional plane B-B,

(7) FIG. 7 shows a third exemplary embodiment of a glass melting plant according to the present invention, in a top view,

(8) FIG. 8 shows a fourth exemplary embodiment of a glass melting plant according to the present invention, in a top view,

(9) FIG. 9 shows the fourth exemplary embodiment of a glass melting plant according to the present invention according to FIG. 8, in a section along the plane C-C, and

(10) FIG. 10 shows a fifth exemplary embodiment of a glass melting plant according to the present invention, in a top view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(11) FIG. 1 shows a melting tank 1 of a glass melting plant (not shown in more detail) of the end-fired type, on whose one side wall 14 there is situated a doghouse 3. The doghouse 3 ends at an inlet 4 of the melting tank 1, and there opens into the melting tank 1. At the left side of FIG. 1, i.e., at a side wall 17 of the melting tank 1, burner ports 5, 6 are indicated of the two burners situated alongside one another, with the supply of the oxidant and of fuel. Connected to these, for regenerative heat recuperation, are two chambers (also not shown) of a regenerator. At a side wall 15, which is situated opposite the side wall 17 with the burner ports 5, 6, there is situated a preferably channel-shaped outlet 2 of melting tank 1, which is used for the removal of the glass melt.

(12) The glass melting plant is continuously fed with unmelted charge material 7. Here, the charge 7 is supplied to the doghouse 3 via a feeding device (not shown). This is indicated by arrow 8. From there, the charge 7 is pushed onto a glass melt 9. As long as the charge 7 has not yet completely melted, it floats on the glass melt 9, whose surface is indicated by a broken line in FIG. 2, and is heated from above via heat or flame radiation in a burner compartment or chamber 22, and at the same time from below by the glass melt 9 through heat conduction. The heat conduction of the covering through the batch 7 is very limited. It is less than 1 W/mK. The heat conductivity of the glass melt 9 is, in contrast, an order of magnitude higher, i.e., greater than 10 W/mK.

(13) The doghouse 3 is limited by side walls 11, 12, 13 and an outlet 4, which form a feeding surface F1 parallel to the direction of transport of the charge. In addition, the doghouse 3 has a floor 26. The (partly melted) glass melt 9 is situated in a basin that ends at a block edge (basin upper edge) 23.

(14) The melt (tank) surface F2 is defined as the base surface of the burner chamber 22 in the region of the melt tank basin, limited by the side walls 14 through 17.

(15) The doghouse 3 has previously been kept small relative to the melt surface F2. The covering of the glass melt 9 with the charge 7 is now reduced in that the doghouse 3 is made significantly and relatively larger. The feeding surface F1 of the doghouse 3 is, according to the present invention, at least 8 m.sup.2, and, given a melt surface F2 greater than or equal to 115 m.sup.2, is at least 7% of the melt surface F2, and, given a melt surface F2 greater than or equal to 90 m.sup.2, is preferably at least 9% of the melt surface F2, and, given a melt surface F2 greater than or equal to 80 m.sup.2, is particularly preferably at least 10% of the melt surface F2. It is advantageous if the feeding surface of the doghouse is at most 25% of the melt surface F2, preferably at most 20%, particularly preferably at most 18% of the melt surface F2.

(16) In conventional glass melting plants, the boundary of the specific load is, for example, greater than 3.5 t/m2*d, and the specific energy consumption, given an addition of shards of >70%, is approximately 960 kWh/t glass (3450 kJ/t).

(17) Modeling calculations have shown that, with the enlargement according to the present invention of the doghouse 3, an increase of the specific melting performance to >5 t/m2*d is possible. In this way, relative to 50% shard additive in the calculation example, the energy consumption can be reduced to 3.3 GJ/t glass.

(18) Such a model calculation is shown in FIGS. 3 and 4. In both cases, the melting plant has a melt surface of melting tank 1, 1 of, in each case, 60 m.sup.2. The feeding surface of the doghouse 3, 3 is standardly not counted as part of the melt surface. The hexagonal feeding surface of the doghouse 3 of the melting plant according to the present invention shown in FIG. 3 is 9 m.sup.2, while the feeding surface of a doghouse 3 of the conventional melting plant shown in FIG. 4 is 2.2 m.sup.2.

(19) The melting performance of the melting plant shown in FIG. 3 is 300 t/d, while the melting performance of the conventional melting plant, shown in FIG. 4, is only 150 t/d.

(20) The not yet melted charge 7 that floats on the melt bath is represented in FIGS. 3 and 4 by trajectories. The free surface 25, 25 of the melt bath, not covered by melt material, is shown by hatching. It can easily be seen that despite the doubling of the melting performance of the melting plant shown in FIG. 3 having a larger doghouse 3, the free surface 25 is approximately equally large relative to the free surface 25 in FIG. 4 in the melting plant with the smaller doghouse 3 and with significantly lower loading. The free surface 25, 25 is substantially responsible for the fact that radiation energy from the firing chamber can penetrate into the melt 9 via the melt surface. The radiation energy penetrates into the glass bath via the free surface, and the melt heated in this way flows, due to density convection, back into the region of the melt material feeding. The hot melt flow promotes the melting off of the melt material underneath the melt material covering.

(21) The doghouse 3 shown in FIGS. 1 and 2 has a roof 18 that has an end wall 20 oriented towards the feeding device, which wall encloses, with the roof 18, a gas compartment 21. The apex of the roof 18 in the gas compartment 21 has a distance h from the block edge 23 of the doghouse 3 of at least 400 mm, preferably at least 500 mm. This is intended to promote the supply of energy through radiation and/or flame gases in the region of the doghouse.

(22) The doghouse 3 can be equipped with an additional electrical resistance heating unit. Examples of this are explained in the following on the basis of FIGS. 5 through 10. The design of the glass melting plants shown in FIGS. 5 through 10 corresponds to that of the first exemplary embodiment shown in FIGS. 1 and 2, except for the electrodes for electrical heating.

(23) The exemplary embodiment shown in FIGS. 5 and 6 has two electrodes 24 in the region of the doghouse 3, which extend into the melt laterally (i.e., transverse to the direction of transport of the charge) from the side walls 11 or 13. The two electrodes 24 are situated opposite one another, and form an electrode pair.

(24) The electrodes 24 extend into the melt with a front segment having a length X (length measured from side wall 11 or 13). The length X of the segment is at least 200 mm, preferably at least 400 mm, and/or preferably at most 1200 mm.

(25) In addition, the electrodes 24 have a distance Y from the end wall 20 of the doghouse 3. The distance Y is measured parallel to the direction of transport of the charge. The distance Y from the end wall is at least 400 mm, preferably at least 700 mm, and/or preferably at most 2000 mm.

(26) In addition, the electrodes 24 are situated at a distance Z (cf. FIG. 6) from the block edge 23 of the doghouse 3 that is at least 200 mm, preferably at least 400 mm, and/or preferably at most 800 mm. The distance Z is measured in the direction of the floor 26 of the doghouse 3, starting from the block edge 23 of the doghouse 3.

(27) The exemplary embodiment shown in FIG. 7 has a further laterally situated pair of electrodes 24. These are situated at a distance Y2 from the first electrode pair 24 that is at least 200 mm, preferably at least 400 mm, and/or preferably at most 2000 mm. The distance Y2 is also measured, analogous to the distance Y, parallel to the direction of transport of the charge in the doghouse 3.

(28) In comparison with the exemplary embodiment shown in FIGS. 5 and 6, the exemplary embodiment of FIGS. 8 and 9 has a further floor electrode 25 that is situated approximately centrally between the two lateral electrodes 24 in the floor 26 of the doghouse 3, and extends into the melt oriented upward, also transverse to the direction of transport of the charge in the doghouse 3. The floor electrode 25 has the same distance Y from the end wall 20 as do lateral the electrodes 24.

(29) The further exemplary embodiment shown in FIG. 10 of a glass melting plant according to the present invention is a combination of the exemplary embodiments according to FIG. 7 and FIGS. 8/9, with regard to the configuration of the electrodes. It has two pairs of lateral electrodes 24, 24, and a respective floor electrode 25, 25 that is assigned to a pair of lateral electrodes 24, 24.

(30) Alternatively, or in addition, as illustrated in FIG. 2, the melt 9 in the doghouse 3 can also be heated with at least one burner 28 immersed in the melt from the floor 26, operating with any type of fuel, in particular, combustible gases. This heating technology causes the formation of bubbles, but can be used in the present case because after the doghouse 3 there follows a melting tank 1 which makes it possible for such bubbles to be removed.

(31) As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

LIST OF REFERENCE CHARACTERS

(32) 1, 1 melting tank 2 outlet 3, 3 doghouse 4 inlet of melting tank 1 5 burner port 6 burner port 7 feeding material (charge, not melted) 8, 8 arrow (identifies the supply of feeding material by a feeding device) 9 glass melt 11 side wall of doghouse 3 12 side wall of doghouse 3 13 side wall of doghouse 3 14 side wall of melting tank 1 15 side wall of melting tank 1 16 side wall of melting tank 1 17 side wall of melting tank 1 18 roof 20 end wall of doghouse 3 21 gas compartment 22 burner compartment/chamber 23 block edge (basin upper edge) of doghouse 3 24, 24 electrode 25, 25 floor electrode 26 floor of doghouse 3 27, 27 free surface without batch covering 28 burner port F1 feeding surface F2 melt surface