Currents In Glass Tanks - A Problem Of Equilibrium

This paper surveys the knowledge of convection currents in glass tanks obtained from plant observations and model studies. The influence of the method of observation and of the conditions of the furnace on the results obtained is discussed. A distinction is made between internal causes of glass currents due to temperature differences in the glass and external causes due to the rate of feed, glass discharge, and forces due to flame heating. Boundary layers between the main currents are caused by temperature differences, and there is a bottom layer which does not participate in the convection movement. The force required to push in the layer of batch sets up a movement which reaches down to the bottom glass.