Studies in Furnace Analysis: Evaluation of Performance Characteristics of a Laboratory Furnace

I t is now well established from numerous studies of experimental and industrial furnaces that the variation of thermal input (He) with useful output (H,) for any furnace is described by the Firing Equation: where the Firing Constants, Ht , aO, and II. m, are the Idle Heat, the Intrinsic Efficiency, and the Maximum Output, respectively. The theoretical developments have broadly established the expected dependency of the Firing Constants on the equivalence ratio (Excess Air); but test of those dependencies is still limited. Using data obtained from a small laboratory furnace, this paper examines some of those dependencies, with particular attention given to Excess Air and the problem of reducing the firing data to a common stoichiometric base to be able to test the applicability of the Firing Equation. Excess Air in the experiments ranged from 10% to 55%, with the firing rate increasing appropriately. Generalization of the results obtained also shows analytically and quantitatively the low firing rate increase with Excess Air for furnaces of high Intrinsic Efficiencies, with the converse for low Intrinsic Efficiency furnaces. This result is well known qualitatively; it is not known, however, to have been reported previously as a quantitative generalization obtained analytically as presented in this paper.