Modelling, Measurement and Analysis of Fluidised Bed Dryer using an ECT Sensor

R. S. Raghavan1, P. Senior1, H. Wang2, W. Yang2 and S. Duncan3

1. School of Chemical Engineering and Analytical Science, The University of Manchester, PO Box 88, Manchester M60 1QD, UK, Email: r.s.raghavan@manchester.ac.uk

2. School of Electrical and Electronic Engineering, The University of Manchester, PO Box 88, Manchester M60 1QD, UK

3. Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK

   
   

   ABSTRACT

   
   

   In the pharmaceutical industry, fluidised bed dryers are used to dry wet particles prior to compression. Although electrical capacitance tomography (ECT) has been traditionally used to obtain images of the fluidisation processes, in this research, capacitance measurements from an ECT sensor mounted on a lab-scale fluidised bed dryer were used to estimate solids concentration and moisture content profiles. Variation of permittivity with temperature and frequency were analysed theoretically. The experimental results show a clear distinction of moisture content profiles at different stages of drying. ECT provides an online volumetric analysis of the sample being dried, eliminating the need to take offline lab measurements. The ECT sensor was simulated using COMSOL in 3D and the simulation results were compared with and validated by the experimental results. The permittivity curves obtained by simulation improve the knowledge of material composition with different electrical properties in the fluidised bed dryer and also provide additional information for system calibration.

   
   

   Keywords: ECT, COMSOL, fluidised bed, solids concentration, moisture content