Ppg Industries, Inc.

Leonard A Knavish

Richard L Cerutti

Joseph A Gulotta

John E Sensi

David R Haskins

William C Harrell

Premature dissociation of fining agent is avoided in a glass melting operation while controlling the final redox state of the product glass by initiating the melting process under relatively oxidizing conditions and subsequently altering the redox conditions to make the glass more reducing. A glass that is more reduced than usual can thereby be produced without sacrificing the ability to adequately fine the glass. For a given redox level, less fining agent need be used, thereby lowering emissions from the melting operation, because dissociation of the fining agent is delayed until a later stage of the process where the redox conditions are changed.

Melting glass with oxidation control and lowered emissions

Nickel sulfide stones are avoided in a glass melting operation by electrolytically maintaining oxidizing conditions near the bottom of the upstream portion of a melting furnace at a location upstream from the establishment of a spring zone.

Avoidance of nickel sulfide stones in a glass melting operation

In a method of making glass or the like, wherein the batch materials are liquefied in a distinct zone from the refiner, the liquefied material is heated in an intermediate stage before being fed to the refiner. In preferred embodiments the intermediate stage comprises one or more channels extending from the side of the refiner.

Multi-stage process and apparatus for refining glass or the like

A horizontal glassmaking furnace adapted for melting glass batch materials by the application of heat to them from overhead flames within the furnace is provided with submerged electric heating electrodes in a region adjacent to where glass batch materials are charged to the furnace and, while overhead flames are reduced or eliminated above the glass batch materials in the vicinity of the electrodes, the glass batch materials are melted from below by action of the electrodes; overhead flames are maintained above exposed molten glass where the glass batch materials have already melted. Discharge of particulate batch materials from the furnace by action of overhead flames is substantially reduced while the thermal efficiency of the furnace is enhanced.

Horizontal glassmaking furnace

A vertically elongated glassmaking furnace is provided with two groups of electrodes: one group is positioned in the upper portion of the furnace and is operated to melt glass batch and to establish an upward flow of hot glass along the center of the furnace; a second group is positioned in the lower portion of the furnace and operated to slow the downward flow of molten glass through the furnace, particularly near the walls of the furnace so that all the molten glass in the lower portion of the furnace flows uniformly downwardly to discharge at a rate sufficiently slow to insure the upward escape of seeds or bubbles from the discharged glass.

Vertical glassmaking furnace and method of operation

Flat glass is produced by advancing a layer of molten glass on the surface of molten metal while cooling it sufficiently to form a continuous sheet of glass which is lifted upwardly from the surface of the supporting pool of molten metal and conveyed upwardly from it for further processing. A method is provided for selectively controlling the temperature, and thus the viscosity, of the glass of selected portions across the width of the continuous sheet of glass in order to adjust and maintain the relative lengths of the respective portions of the continuous sheet of glass as it is lifted upwardly from the supporting pool of molten metal and to thereby control the flatness of the continuous sheet of glass as it is ascending from the supporting pool of molten metal.

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Plum Borough, PA, United States of America

Leonard A Knavish