Process and device for melting and fining glass
The invention relates to a process and a device for manufacturing molten glass comprising from upstream to downstream a furnace for melting and fining glass equipped with cross-fired overhead burners, then a conditioning basin supplied with glass by the furnace, the dimensions of this manufacturing device being such that K is higher than 3.5, the factor K being determined from the dimensions of the device. The invention makes it possible to dimension a device for melting glass so that it is smaller and consumes less energy while producing high quality glass.
1. A process for manufacturing molten glass in a device comprising, from upstream to downstream, a furnace for melting and fining glass equipped with cross-fired overhead burners, and then a conditioning basin comprising one or more compartments, the process comprising melting glass in the furnace,
wherein:
the furnace comprises a melting zone and a fining zone;
the bottom of the fining zone and the bottom of the conditioning basin are deep enough that a single downstream recirculation loop passes through the fining zone and through all the compartments of the conditioning basin;
the conditioning basin is supplied with glass by the furnace; and
the dimensions of the device are such that K is higher than 3.5, where:
K
=
K
a
+
∑
i
K
S
i
,
in which:
K
a
=
0.000727
×
S
f
×
∫
x
0
x
1
[
P
(
x
)
]
2
[
σ
(
x
)
]
3
dx
;
S f represents the area under flame in the furnace;
x 0 is the abscissa in the general flow direction of the glass of the end of the area under flame in the furnace;
x 1 is the abscissa in the general flow direction of the glass of the end of the conditioning basin;
σ(x) represents the area of the cross section of flow of the glass of the device at the abscissa x;
P(x) represents the perimeter of the cross section of flow of the glass of the device at the abscissa x; and
Σ i K Si represents the sum of the K Si due to a singular element in the device downstream of the area under flame in the furnace, a singular element producing, from upstream to downstream and over less than 2 m in the flow direction of the glass, a decrease in the cross section of flow of the glass of more than 10% then an increase in the cross section of flow of the glass of more than 10%, where
K
S
i
=
0.0012
×
(
exp
[
5.16
(
σ
i
-
σ
S
i
σ
i
)
2.55
]
-
1
)
(
S
f
σ
i
)
2
;
σ i representing the area of the cross section of flow of the glass just upstream of the singular element S i ; and
σ Si representing the area of the minimum cross section of flow produced by the singular element S i .
2. The process of claim 1 , wherein K>5.5.
3. The process of claim 2 , wherein K>7.5.
4. The process of claim 3 , wherein K is higher than 9.
5. The process of claim 1 , wherein a ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.4.
6. The process of claim 5 , wherein the ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.6.
7. The process of claim 6 , wherein the ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.8.
8. The process of claim 1 , wherein the furnace is sufficiently deep that an upstream recirculation loop and the downstream recirculation loop form in the furnace.
9. The process of claim 1 , wherein the conditioning basin comprises, from upstream to downstream, a neck then a working end.
10. The process of claim 1 , wherein the furnace has a capacity of 500 to 1500 m 3 of glass.
11. The process of claim 1 , having a pull of 400 to 1300 tonnes of glass per day.
12. The process of claim 1 , wherein the cross-fired overhead burners use an oxidant comprising 10 to 30 vol % O 2 , and are equipped with regenerators and function pairwise in reversal mode.
13. The process of claim 1 , wherein the cross-fired overhead, burners use an oxidant containing 80 to 100 vol % O 2 .
14. The process of claim 1 , wherein in the conditioning basin in any vertical plane transverse to the longitudinal axis of the furnace, there are points in the glass having a longitudinal velocity component pointing from downstream to upstream.
15. The process of to claim 1 , wherein after the conditioning basin, the glass passes into a channel itself supplying a forming device, with no backflow occurring in the channel.
16. The process of claim 15 , wherein a length of the channel ranges from 0.3 to 10 m.
17. A process for manufacturing flat glass, the process comprising manufacturing a molten glass with the process of claim 1 , and then forming the molten glass into flat glass by floating the molten glass on a molten metal bath in a float chamber.
18. A device for manufacturing molten glass, the device comprising, from upstream to downstream, a furnace for melting and fining glass equipped with cross-tired overhead burners, and then a conditioning basin comprising one or more compartments,
wherein:
the furnace comprises a melting zone and a fining zone;
the bottom of the fining zone and the bottom of the conditioning basin are deep enough that a single downstream recirculation loop passes through the fining zone and through all the compartments of the conditioning basin;
the conditioning basin is supplied with glass by the furnace; and
the dimensions of the device are such that K is higher than 3.5, where:
K
=
K
a
+
∑
i
K
S
i
,
in which:
K
=
0.000727
×
S
f
×
∫
x
0
x
1
[
P
(
x
)
]
2
[
σ
(
x
)
]
3
dx
;
S f represents the area under flame in the furnace;
x 0 is the abscissa in the general flow direction of the glass of xe end of the area under flame in the furnace;
x 1 is the abscissa in the general flow direction of the glass of xe end of the conditioning basin;
σ(x) represents the area of the cross section of flow of the glass of the device at the abscissa x;
P(x) represents the perimeter of the cross section of flow of the glass of the device at the abscissa x; and
Σ i K Si represents the sum of the K Si due to a singular element in the device downstream of the area under flame in the furnace, a singular element producing, from upstream to downstream and over less than 2 m in the flow direction of the glass, a decrease in the cross section of flow of the glass of more than 10% then an increase in the cross section of flow of the glass of more than 10%, where
K
S
i
=
0.0012
×
(
exp
[
5.16
(
σ
i
-
σ
S
i
σ
i
)
2.55
]
-
1
)
(
S
f
σ
i
)
2
;
σ i representing the area of the cross section of flow of the glass just upstream of the singular element S i ; and σ Si representing the area of the minimum cross section of flow produced by the singular element S i .
19. The device of claim 18 , wherein K>5.5.
20. The device of claim 19 , wherein K>7.5.
21. The device of claim 20 , wherein K is higher than 9.
22. The device of claim 18 , wherein a ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.4.
23. The device of claim 22 , wherein the ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.6.
24. The device of claim 23 , wherein the ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.8.
25. The device of claim 18 , wherein
a ratio of the area under flame in the furnace to the area of the conditioning basin is lower than 4.
26. The device of claim 18 , wherein the furnace is deep enough that an upstream recirculation loop and the downstream recirculation loop form in the furnace.
27. The device of claim 18 , wherein the conditioning basin comprises, from upstream to downstream, a neck then a working end.
28. The device of claim 18 , wherein the furnace has a capacity of 500 to 1500 m 3 of glass.
29. The device of claim 18 , having a pull of 400 to 1300 tonnes of glass per day.
30. The device of claim 18 , wherein the cross-fired burners use an oxidant comprising 10 to 30 vol % O 2 , and are equipped with regenerators and function pairwise in reversal mode.
31. The device of claim 18 , wherein in the conditioning basin in any vertical plane transverse to the longitudinal axis of the furnace, there are points in the glass having a longitudinal velocity component pointing from downstream to upstream.
32. The device of claim 18 , wherein after the conditioning basin, a glass being manufactured passes into a channel itself supplying a forming device, with no backflow occurring in the channel.
33. The device of claim 32 , wherein a the length of the channel ranges from 0.3 to 10 m.
34. A device for manufacturing flat glass, the device comprising the device of claim 18 , and a float chamber in which a molten glass is floated on a molten metal bath.
35. The device of claim 18 , further comprising, over its entire length, tank blocks containing the molten glass, wherein glass height is a distance between the upper level of the tank blocks decreased by a safety margin of between 30 and 130 mm and the level of the bottom.
36. The process of claim 3 , wherein K is higher than 10.5.
37. THE process of claim 1 , wherein:
K>5.5;
a ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.4;
the furnace is sufficiently deep that an upstream recirculation loop and the downstream recirculation loop form in the furnace;
in the conditioning basin in any vertical plane transverse to the longitudinal axis of the furnace, there are points in the glass having a longitudinal velocity component pointing from downstream to upstream; and
after the conditioning basin, the glass passes into a channel itself supplying a forming device, with no backflow occurring in the channel.
38. The device of claim 20 , wherein K is higher than 10.5.
39. The device of claim 18 , wherein:
K>5.5;
a ratio of the area under flame in the furnace to the area of the conditioning basin is higher than 1.4;
the furnace is deep enough that an upstream recirculation loop and the downstream recirculation loop form in the furnace;
in the conditioning basin in any vertical plane transverse to the longitudinal axis of the furnace, there are points in the glass having a longitudinal velocity component pointing from downstream to upstream; and
after the conditioning basin, a glass being manufactured passes into a channel itself supplying a forming device, with no backflow occurring in the channel.