Three-Dimensional Flow and Thermal Structures in Glass Melting Furnaces. Part I. Effects of the Heat Flux Distribution.

This paper presents a study of the flow and thermal structures in the molten glass bath of a typical glass melting furnace with a throat but without air bubblers or electric boosting. Different separate effects on the flow structure of the glass melt are simulated, but only the glass melt is considered. The net heat flux distribution is imposed at the combustion space/glass melt interface, and its effects on the flow and thermal structures of the glass melt are analyzed in a systematic manner by changing the heat flux distribution while keeping the total heat input to the glass bath constant. The main purpose of the work is to evaluate the capability of the furnace operators to control the glass flow and temperature fields by adjusting the firing in the combustion space. The physical phenomena affecting the flow structure in the glass melt are analyzed and discussed in detail. The major results of the study indicate that (i) the heat flux distribution has no significant effect on the flow structure of the glass melt under the batch blanket where several Rayleigh-Benard cells develop in the spanwise direction, (ii) a heat flux gradient in the longitudinal direction is required to generate two recirculation loops in the direction, and (iii) steep heat flux gradient in the refining part of the tank increase significantly the size of the refining recirculation loop near the front wall. NOMENCLATUR