Basic flow pattern and its Variation in different types of glass tank furnaces

Abstract

The mohen glass current in tank furnaces was studied by physical modelling. The basic flow pattern was divided into batch, melting, stagnant buffer, refming and conditioning regions. Every region and its special function are discussed here. The forming me chanism of the stagnant buffer area and the nearer or farther return position of back current, in particular, are presented with a new approach. A pull current path within the glass melt in tank furnaces was assumed. Along this path the pull current has minimum residence time. This is a key parameter to analyze the process of efficient glass melting. Based on the model assumed, several operating stages with the changes in furnace structure are discussed. The factors affecting the pull current path must be those that mainly influence the whole melting process. The conclusion is supported by the Observation and measurement in the physical model . It also shows good agreement with operating experiences on actual furnaces. Through the research work in a series of furnaces, the authors have found that the flow pattern in tank furnaces wi th a throat greatly differs from that in open cross-fired furnaces without a throat. There is a strong back current from conditioning t ank to melting tank in the latter one. But for the furnace with a throat little back current could be found through the throat to the melting tank, i.e., the pull current in forward flow is not diverted and raised at the hot spot and therefore can flow directly along the bottom to the throat. No triangle stagnant area exists in this type of furnace. In order to overcome this shortcoming, measures are proposed and discussed in the paper.