Geldart A, B and D particles have conducted extensive studies on the application in gas-solid separation fluidized beds. There have been differences in research operations and environmental conditions. Besides, there has been extensive research on Geldart A, B and D particles before, but it is not possible to systematically compare and analyze the bubble hydrodynamic between different particles horizontally. In addition, there is limited research on the bubble hydrodynamics of Geldart A- particles, namely mixture of Geldart A particles with slight amount of Geldart C particles. Therefore, this study aims to investigate the differences of bubble hydrodynamics in Geldart A, B, D and A- particle fluidized beds. Using digital image analysis technology (DIAT) and Lagrange velocity technology (LVT) study the bubble hydrodynamics of the above four particles in a two-dimensional gas-solid fluidized bed. For Geldart A, B and D particles, the bubble number and size distribution are basically consistent with previous research. There is a positive correlation between bubble size and particle size. After adding coal powder, the bubble coalescence frequency further decreases, which contributes to bubble size also decreases. The bubble size distribution is more uniform. Due to the absence of bubble rupture in the Darton bubble growth model, a new correlation which has an error range of about 15% based Darton bubble growth model is more accurate in predicting bubble size. Additionally, the bubble rising velocity is related to their diameter, smaller bubbles rising slower and larger bubbles rising faster. Davidson correlation is a fantastic tool for predicting bubble rising velocity. By modifying the Davidson correlation coefficient relating to the particle properties can effectively predict the bubble rising velocity. Subsequently, the values of the coefficient are within 15% are given.

Gas-solid separation fluidized bed,Bubble hydrodynamics,Single and binary dense medium,Digital image analysis technology