Industrial electric heating furnaces – Glass furnace device – Joule effect heating
Patent
1992-01-22
1993-09-07
Reynolds, Bruce A.
Industrial electric heating furnaces
Glass furnace device
Joule effect heating
373 29, 373 31, 373 34, 65 27, 65134, 65335, C03B 300
Patent
active
052436217
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method of feeding glass batch to a glass-melting furnace.
SUMMARY OF THE INVENTION
In accordance with the present invention a method of feeding glass batch to a glass-melting furnace includes the step of feeding powdered glass batch vertically downwardly through a hot air environment, applying infra-sound to the hot air environment containing the powdered glass batch to facilitate transfer of heat from the hot air environment to the powdered glass batch and, subsequent to the said heat transfer, adding fuel to the heated glass batch to raise the temperature of the glass batch to melting temperature.
The application of the infra-sound facilitates transfer of heat from the hot air environment to the powdered glass batch by imposing a vibrational relative movement between the hot air and the powdered glass batch.
Preferably in accordance with the present invention the heat transfer from the hot air environment to the glass batch cools the hot air environment to a temperature of the order of 700.degree. C. or even to a temperature lower than 700.degree. C.
Such cooling of the hot air environment is important in substantially reducing the propensity of the airstream to produce nitrogen oxides (NO.sub.x) when the airstream reacts with fuel immediately upon the combustion resulting from the introduction of the fuel.
The hot air environment is advantageously provided by an airstream which is pre-heated by waste gases from the glass-melting furnace. The airstream is preferably pre-heated to a temperature of the order of 1,200.degree. C.
Such pre-heating may be effected in stages by passing air from the atmosphere through successive heat exchangers.
More specifically in accordance with the present invention, there is provided a method of feeding glass batch to a glass-melting furnace for making a vitreous material comprising the steps of passing a heated airstream containing air at a temperature in excess of 1,000.degree. C. vertically downwardly towards the crown of the glass-melting furnace, introducing powdered glass batch into the vertically moving heated airstream, applying infra-sound to the vertically moving heated airstream to vibrate the heated airstream and effect heat transfer from the airstream to the glass batch particles to heat the glass batch particles and reduce the temperature of the heated airstream below 700.degree. C., subsequently adding fuel as the heated glass batch particles and the cooled airstream move downwardly towards the crown of the furnace, and passing a stream of glass batch, burning fuel and air downwardly through the crown of the furnace such that there is direct contact between the flame of the burning fuel and the surface of molten glass within the furnace, and the glass batch is melted.
In the embodiment of the invention which will be described, the fuel is added around a circumference of the downwardly moving airstream and heated glass batch particles, but the fuel may be injected into the downwardly moving airstream and heated glass batch particles.
By the use of the present invention it has proved possible to form glasses having high melting points, for example a melting point in excess of 1400.degree. C., which have proved difficult to produce in conventional furnaces.
The present invention will be further understood from the following detailed description of preferred embodiments thereof which is made, by way of example, with reference to the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a and 1b are respectively elevation and plan views of apparatus including a furnace for carrying out the method of present invention,
FIG. 2 is a graph showing the relationship between the production of nitrogen oxides (NO.sub.x) upon gaseous combustion in pre-heated air and the temperature of the pre-heated air when the fuel is introduced and combustion is commenced, and
FIG. 3 is a diagrammatic representation of an alternative apparatus for carrying out the method of the present invention.
DESCRIPTION
REFERENCES:
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patent: 4752314 (1988-06-01), Fassbender et al.
patent: 4789990 (1988-12-01), Pieper
Hoang Tu
Reynolds Bruce A.
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