Quantitative comparison of measurement quality of cross-correlation based particle velocity instruments in different gas fluidization regimes

Abstract

Particle velocity measurement based on cross-correlation algorithm is used widely in various multiphase flow systems. In this study, an optical fiber probe, i.e. Labasys® 100 from MSE Meili was used to systematically compare the qualities of its measured particle velocities in a pair of hydrodynamically distinct regimes, i.e. a fast fluidized bed (FFB) and a bubbling fluidized bed (BFB). Compared to FFBs, the measured particle velocities in BFBs show lower data repeatability, higher percentage of invalid data and higher sensitivity to the selection of the threshold value of maximum cross-correlation coefficient, which corresponds to much lower measurement qualities in this regime. Comparatively, higher measurement qualities were observed in the FFB based on the same evaluating methods. The highest measurement qualities appear in the core region of the riser and under high superficial gas velocities. A matchup relationship between the measurement quality and the shape of the probability density function (PDF) curves of maximum cross-correlation coefficient is found. Narrower PDF curves correspond to higher measurement quality and vice versa.