Mathematical model and numerical solutions for the coupled gas-solid heat transfer process in moving packed beds

A theoretical study was performed into the coupled gas-solid heat transfer process in a moving cooling packed clinker bed. A mathematical model for the clinker cooling process including effects from clinker movement is proposed. The aim is to predict through numerical methods the temperature distribution in the clinker layer and determine the optimal operating conditions. The equations and boundary conditions are discretized using the Taylor series expansion. The Jacobi iteration algorithm is employed to solve the difference equations to obtain temperature distributions for the clinker cooling process. The results are validated using industrial data. The relative, errors are 7.0% and 1.1% for secondary and tertiary air temperatures, respectively. An analysis of the temperature difference distribution between clinker and cooling air confirmed the need to apply thermal non equilibrium conditions in packed bed modeling. The different clinker speeds and thicknesses are also calculated. The results show that, with the same thickness of clinker layer, the most effective speed of the clinker is 0.008 m/s and ensures clinker cooling and heat recovery requirements. With the same clinker mass flow rate, operating with a thicker clinker layer can improve heat recovery and decrease the clinker outlet temperature; both can be used as a guiding framework in real cement production.