Measurements of pressure drop and particle velocity in a pseudo 2-D rectangular bed with Geldart Group D particles

A small scale pseudo 2-D bed of dimension 0.075 m x 023 m x 122 m was utilized to measure the pressure drop and velocity statistics of Geldart Group D nylon beads. The pressure drop was measured using a fast-response pressure transducer and the particle velocities were measured with high speed particle image velocimetry, with particle tracking, in a slugging flow regime for three different superficial gas velocities (2, 3 & 4 times the minimum fluidization velocity (U-mf)). At superficial gas velocity of 3 U-mf, the measured slugging frequency was about 2.5 Hz, while at conditions close to 2 U-mf and 4 U-mf, the slugging frequency was about 1.5 and 1.7 Hz. Additionally, at 3 U-mf condition, the bed exhibited a much higher root mean square (RMS) of pressure drop fluctuations than those at 2 U-mf and 4 U-mf. The varying trend suggested an existence of a complicated regime change for these shallow bed measurements that had not been previously explored. The measurement of millions of individual particle velocities at the vicinity of the wall had enabled accurate measurement of higher order statistics including RMS, granular temperature, skewness, and kurtosis of particle velocity. The measured skewness and kurtosis of the velocity distribution indicated that the particle velocity distribution deviated substantially from a normal distribution as the intersection of walls of the rectangular bed was approached. (C) 2016 Elsevier B.V. All rights reserved.