Measurement techniques in fluidized beds

Quantities that need to be measured in gas fluidized-bed systems include so lids volume concentrations, solids velocities and solids mass flows, the ve rtical and horizontal distribution of solids inside the system, the lateral distribution of the fluidizing gas, temperatures and gas concentrations. I n the present paper an overview is given on available measuring techniques. In the first section techniques for industrial routine measurements are di scussed. These are mainly temperature and pressure drop measurements. Pract ical applications and also the limitations of these techniques are outlined . In the second section more sophisticated techniques for local measurement s inside fluidized bed systems, which have already proven their suitability in large-scale industrial reactors, are dealt with. Examples include sucti on probes for measurements of local solids mass flows, heat transfer probes for the detection of defluidized zones and solids flows inside fluidized-b ed reactors and capacitance probes for solids concentration and velocity me asurements under high-temperature conditions. The third section finally pre sents advanced techniques which are either still under development or which are particularly intended for academic investigations of basic fluidizatio n phenomena. Examples include sensor techniques, imaging and tomographic me thods. (C) 1999 Elsevier Science S.A. All rights reserved.