Flow regime identification in a three-phase bubble column based on statistical, Hurst, Hilbert-Huang transform and Shannon entropy analysis

摘要

Flow regime transitions in a gas-liquid-solid three-phase bubble column were investigated based on pressure time series. The statistical, Hurst, Hilbert-Huang transform and Shannon entropy analysis methods were applied to differential pressure fluctuation data measured in a two-dimensional (2-D) bubble column measuring 0.1m in length and 0.01m in width equipped with a sintered plate distributor (average diameter of holes was 50μm). Air was used as the gas phase and tap water as the liquid phase. Glass beads measuring 150μm in size with a particle density of 2500kg/m~3 constituted the solid phase. Based on sudden changes in both the EMD energy entropy from Hilbert-Huang transform and the Shannon entropy values, two flow regime transition gas velocities were successfully identified: the homogeneous regime shifted to the transition regime at a superficial gas velocity of 0.069m/s; and the transition regime shifted to the heterogeneous regime at a superficial gas velocity of 0.156-0.178m/s. The transition gas velocities showed good agreement with the experimental results. The EMD energy entropy and Shannon entropy analysis methods can reveal the complex hydrodynamics underlying gas-liquid-solid flow and are confirmed to be reliable and efficient as non-invasive methods for detecting flow regime transitions in three-phase bubble column systems.