The Development of a Heat and Mass Transfer Model for a Shaft Kiln to Preheat Manganese Ore with Hot Air, Model Development Methodology

Abstract

This work models the design of a preheater (shaft kiln ) to demonstrate preheating of manganese ores with hot air at 800 °C produced by concentrating solar thermal energy on a pilot scale. This paper reports the methodology for the development of a heat and mass transfer model that informs the effective control of the shaft kiln air flow rates . A continuum approach is followed through the discretisation of the fluid and solid phases of a packed bed of randomly packed lumpy mineral ore. The fluid dynamics of the packed bed is solved using correlations for fluid flow through packed beds and the dimensionless constants for flow, heat convection and conduction are quantified for a packed bed of manganese ore. The required pressure drop across the shaft kiln with fluid flow up to 5 m/s is less than 100 kPa. It was also found that a lumped system does not exist in the solid phase. The validity of the model will be studied theoretically and through experimental work. Outstanding work on the methodology includes the solution to the radiative heat transfer, convective mass transfer, and the method to measure the extent to which the wall effect impacts on the radial temperature distribution.