Influence of intensifying means upon technological characteristic of glassmelting furnaces

The method of three-dimensional mathematical modelling by means of CFD prog ram FLUENT was used to find the influence of means of intensification upon technological characteristics of grass melting furnaces. Two physical means , i.e. a mechanical barrier and melting tank insulation (or heat losses thr ough walls and bottom) were selected to intensify a melting process. Techno logical characteristics were defined by the magnitude and shape of temperat ure and velocity fields and by the volume of glass melt with the temperatur e lower than the temperature liquidus. The results of mathematical modeling have shown the considerable influence of the pull of the furnace, of the m agnitude of thermal losses through the walls and the bottom and of the heig ht of a mechanical barrier. The temperature of glass melt flowing into the throat is increased by a height of a barrier and decreased by heat losses. The temperature 1200 degrees C which corresponds with glass melt viscosity h = 10(3) dPa was considered to be the lowest limit of the temperature of g lass melt coming to a throat. Variants with this temperature lower then 120 0 degrees C have not satisfied this evaluating criterion. The velocity of t he glass melt flowing into the throat is increased by the pull of the furna ce (18 t day(-1) corresponds with 9.38 X 10(-4) m s(-1); 50 t day(-1) corre sponds with 2.62 x 10(-3) m s(-1) and by the heat losses. The heat losses a lso influence the volume of "dead areas" (the higher the heat losses the la rger the "dead areas"). Only the variants with a = 1 W m(-2) K-1 and two va riants with a = 3 Wm(-2) K-1 have satisfied the criterion of zero "dead are as ". The height of a barrier influences the shape of velocity pra;ii[es, i .e. the presence of the backward current. If this height h = 0. 75 m, the r eturn current cannot be observed On the other hand the mechanical barrier w ith the smallest height h = 0.375 m actually did not influence the current in a melting tank. All the above mentioned evaluating criteria have been sa tisfied by only 17 variants from the whole number of 92 investigated ones. The investigated glass melting furnace should be operated with very low coe fficient of heat transfer at walls and bottom. The pull of the furnace can be kept at 40 t day(-1). The height of a mechanical barrier should range be tween 0.5 m and 0. 625 m from the furnace bottom. Significant influence of distance bent een a mechanical barrier and a charge wall has not been prove d so the barrier can be situated across the melting tank with the proximity 4. 75 - 5.5 m to the frontal charge wall.