Rd. Abellon et al., A SINGLE RADIOTRACER PARTICLE METHOD FOR THE DETERMINATION OF SOLIDS CIRCULATION RATE IN INTERCONNECTED FLUIDIZED-BEDS, Powder technology, 92(1), 1997, pp. 53-60
A non-intrusive method is presented to determine the residence times o
f a single particle in a facility composed of four interconnected flui
dized beds (IFB) with glass beads fluidized by air above minimum fluid
ization at ambient temperature, It uses a glass particle labelled with
radioactive Na-24 or Ir-192 whose gamma-ray emissions are monitored b
y two external NaI(Tl) scintillation detectors. It is shown that, with
in the batch particles' size range, the mean residence time of the rad
iotracer particle is practically independent of the radiotracer partic
le size and the beds can be considered as practically ideally mixed ve
ssels. It is further demonstrated that the method can adequately measu
re the residence time distribution of the particles independent of the
processes occurring within the system such as the generation of stati
c electricity during fluidization. The presence of static electricity
was found to substantially affect the mean residence time of the solid
s. By relating the bed mass and the mean residence time of the radiotr
acer particle, the solids circulation rate within the IFB can be obtai
ned.