Mathematical Modelling of Reversed Flow and Heat Transfer in the Combustion Chamber of the LB Furnace

Abstract

A mathematical model has been developed to describe the turbulent and reversed flow with combustion reaction and radiation heat transfer in a cylindrical combustion chamber. Measured gas velocity and tracer concentration in the cold flow compared well with the mathematical modelling results, and by using the same model for the high temperature reacting flow enables the correct trends in overall heat transfer rates to be predicted. The model was applied to the design of the combustion chamber of the LB furnace. The influences of the location of the combustion air inlet and the preheating temperature of air on the overall heat transfer rate from the flame to the reduction tube, where heat is required, were investigated for process optimization. Through modelling work it is found that 1) radiation dominates the overall heat transfer process in the chamber, 2) the heat transfer rate to the reduction tube in the chamber may be greatly enhanced by adjusting the gas flow and combustion pattern through selecting the air inlet location and preheating the combustion air, and 3) the model is useful as a design tool.