We propose a simple method for accurately estimating the solids circulation
rate in a closed-loop liquid-solid circulating fluidized bed. The techniqu
e is based on the use of radioactive isotopes for estimating the solids vel
ocity and volume fraction distribution in a chosen section of the circulati
ng fluidized bed loop. The method is demonstrated for a liquid-solid circul
ating fluidized bed, and is readily applicable in other systems such as gas
-solids circulating fluidized beds or closed-loop pneumatic and hydraulic t
ransport lines. With minor modifications, the method may be used for indust
rial systems as well. (C) 2001 Elsevier Science B.V. All rights reserved.