Visualisation of production-scale pharmaceutical fluidised bed by electrical capacitance tomography

This paper presents the first demonstration that electrical capacitance tomography (ECT) has been deployed on a production-scale MP-4 FlexStream™ fluidised bed. FlexStream™ is a new multi-purpose processor designed for use in the pharmaceutical industry. It enables three processes, i.e. granulation, drying and coating, to be carried out in one processor. To investigate the hydrodynamic behaviour of gas and solids in the fluidised bed, a 12-electrode ECT sensor has been designed and mounted on the inner wall of the product bowl. Three process stages were observed: (1) bubbling fluidised bed without FlexStream™ air and atomised air, (2) bubbling with FlexStream™ air and atomised air and (3) bubbling with FlexStream™ air and atomised water. In this paper the test results are presented and the data are analysed. The results confirm that by using the capacitance from the adjacent electrode pairs of the ECT sensor, the performance of the spray nozzles can be monitored in real time. This demonstrates the potential that ECT can provide an online tool for monitoring, measurement and control of fluidised beds in the pharmaceutical industry.