Powder Technology, Vol.316, 650-657, 2017
Estimation of solids circulation rate through magnetic tracer tests
This work assesses the solids circulation rate in a circulating fluidized bed cold model based on measuring the particles mean residence time (tau). The tracking method detects fluid-dynamically similar ferromagnetic tracer partides, and is based on inductance changes of a coil due to changes in the concentration of ferromagnetic particles in its core. A section of the model was selected to perform the tracer measurement, such that the variations in the solids volumetric fraction and the solids velocity were negligible, and a correlation between the circulation rate and the mean residence time of solids.could be established. The circulation rate was calculated in this manner for a range of operation conditions, variations of riser fluidization velocity and total inventory were performed. The results were validated measuring the circulation rate by the accumulation method as well, the results show a satisfactory correlation between the tracer and the accumulation methods. The magnetic tracer method appears thus to be suitable for the measurement of solids circulation rates in low temperature applications. This method offers as advantages the possibility for on-line measurement, good sensitivity, non intrusiveness, cost efficiency, and does not require a calibration. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Solids circulation rate;Solids mass flux;Solids mass flow rate;Circulating fluidized beds;Accumulation method;Tracer measurement