GB768932A - Improvements in or relating to cooling section of a forehearth for molten glass - Google Patents

Abstract

768,932. Glass manufacture. EMHART MANUFACTURING CO. May,12, 1955 [June 24, 1954], No. 13793/55. Class 56 The cooling-section of a forehearth of a glass-melting furnace is provided with heating and cooling means which are used as required to produce substantial uniformity of temperature throughout the section of the glass at the spout. The molten glass passing from the' furnace to the cooling section of the forehearth at 11, flows over refractory bottom blacks 10a, 13, the latter sloping downwardly, and under a roof 22 supported by side blocks 21. The slide blocks 21 rest upon burner blocks 20. The part of the glass-flow passage used as a cooling-section is divided into temperature control zones separated by baffle blocks 26, 28 which nearly touch the flowing glass and prevent exchange of gases between the zones. The side blocks 21 are formed with channels 30, 31, the former being for the admission of cooling air which travels under. the concave roof to the exhaust channel 31 which is nearly opposite to it in the opposing block 21. The blocks 21 thus have alternating air-admission and exhaust ports and the oppositely moving streams brush one another and produce eddies in the concavity 41. The exhaust air is led to passages 32 in the roof blocks 22, the bottom of these passages being corrugated at 35 to make efficient use of the cooling air both at upper and under sides of the blocks 22. The effect of the cooling air is to cool the glass stream more at the top than at the bottom. To counter this effect, the cooling-air may be cut off in one zone and hot combustion products from the burner blocks used to raise the temperature of the top glass, and possibly the bottom glass, so that in a subsequent zone where cooling-air only is used, the tendency is towards a uniform temperature throughout the glass stream. The length of the cooling section is determined by the number of zones, separated by baffles 26; 28, each zone having its own heating and cooling means.