Application of image analysis to determine design loading in flighted rotary dryers

The amount of solids contained within the flights and in the airborne phase of a flighted rotary dryer is critical to the analysis of performance and the optimal design of these units. In this paper, image analysis techniques are utilised to estimate the amount of material within the flights of a rotating drum and to determine the optimum loading condition. Multiple photographs of the cross-sectional area of both flight borne and airborne solids within the dryer at different loading conditions are processed. The image analysis process involved contrast enhancement, filtering and thresholding using a combination of tools within both ImageJ and MATLAB. The verification of the process used to estimate the cross-sectional area of material in the flights is described. Alternative methods for estimating design loading are described and their suitability is discussed. The design load was estimated using conventional design criterion based on the saturation of material at the first unloading flight, saturation of the entire upper half of the drum and saturation of the airborne solids.