LAUSR

Abstract Data analysis from downers requires a comprehensive methodology in order to set the data baseline. This analysis can be accomplished by using a mathematical approach based on solid mass balances and an iterative calculation. Each signal baseline is defined as  X  +  n  ∙  σ x , where X is the signal average; σ x is the signal standard deviation; and “ n ” is a baseline parameter. By using this methodology, the noise resulting from secondary reflections is eliminated and all valuable data is kept in the time series. More than 500 experiments with > 50 million data records were obtained using two independent gas-solid circulating fluidized bed downer units of 3 m height and two different diameters (2.54-cm and 5.08-cm ID). The solid used was a FCC catalyst with a mean particle diameter of 84.42 μm and a particle density of 1722 kg/m 3 . Measurements were effected using a CREC-GS-Optiprobe, an optical sensor equipped with a GRIN lens. This lens focus radiation in a 118 ± 34 μm diameter highly irradiated volume, placed at 4.5 mm away from the sensor tip. CREC-GS-Optiprobe sensors do not require calibration and offer minimum intrusion. On the basis of the data obtained, this study reports a valuable methodology, applicable to downer units of different diameters. This leads for the two downers studied to particle clusters with very close asymmetric distributions.