Feedback Control of Moisture in a Batch Fluidised Bed Dryer Using Tomographic Sensor

J.A Villegas1, M. Li2, S.R. Duncan1, H.G. Wang3 and W.Q. Yang3

1. Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK, Email: stephen.duncan@engineering-science.oxford.ac.uk

2. School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK

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

ABSTRACT

In this paper, the modelling and control of material moisture content in a batch fluidised bed dryer are studied. First, a lumped mechanistic model is developed to describe the heat and mass transfer between solid, gas and bubble phases. Experimental validation shows that the model can be used to predict the particle moisture content and temperature profiles during the drying process in the bed dryer. The effect of the wall temperature is investigated by first validating the model with an insulator on the wall and then without the insulator. Finally, feedback control of material moisture content in a bed dryer is studied with tomographic sensors included in the control loop. A proportional plus integral (PI) controller is designed to achieve a desired drying rate for wet materials. Simulations show that it is possible to control the drying rate.

Keywords Fluidised bed dryer, modelling, control, tomography.