PNNL

Abstract

The ability to control melter convection patterns may provide a means of mitigating gas layer buildup under the cold cap, enhancing the heat transfer to the batch, and possible accelerating batch reactions, thereby increasing melt rate and glass throughput. Other operational benefits could result from such control. Convective patterns in an electrically heated melter are dominated by the distribution of Joule heat and thermal boundary conditions for a given melter design and geometry. We believe that control of electrical driving, in particular control of the interaction of electrical fields connected to distinct electrode pairs, can be used to vary the distribution of Joule heat generation. The under-investigated aspect of electrical driving control is the effect of waveform “overlap” of the driving voltages, the “overlap” in the case of harmonic driving being determined by the relative phase. For electrical driving using waveforms chopped by Silicon Controlled Rectifiers (SCRs), the chopping influences the "overlap." This control can provide a means of controlling melt convection. The objective of the present investigation is to test that hypothesis, verifying that such control can be observed for a numerical model of a simple melter geometry.