Measurement of particle recirculation rate with radioactive tracer particles in a large scale circulating fluidized bed boiler

Measurements of particle recirculation rate were made with a pulse injection of radioactive tracer particles in a 80 MWth circulating fluidized bed boiler, Grenaa, Denmark. Two batches of tracer particles were injected to the standpipe at full load and at part load. The response curves of the impulse injection were measured by a set of successive detectors at different locations of the standpipe. The response curves are successfully described by a cascade-tanks model. The particle recirculation rates estimated are about 9.5 kg/[m2.s] at full load and about 2 kg/[m2.s] at part load. (au)