Authors: Hongliang Xiao a, Yongmin Zhang a, Junwu Wang b, c, d
a State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
b State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing 100190, China
c School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
d Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China
Source: This paper was published in Chemical Engineering Science, Volume 253.
Abstract: Solids velocimetry based on cross-correlation algorithm has been widely used in multiphase systems. Recent studies have revealed that its measurement qualities depend critically on fluidization regimes, and the underlying mechanism was supposed to be the competition between solids convection and mixing. In this study, a method was proposed to analyze the local solids residence time distribution (RTD) from the results of Eulerian-Lagrangian simulations. Systematic simulations were then conducted to acquire the local solids RTDs in various gas-solids fluidization regimes. Afterward, the local Péclet numbers were quantified. It was found that the measurement qualities are intimately related to the local Péclet numbers and the solids convection-mixing competing mechanism. Present study revealed the underlying mechanism of the success and failure of cross-correlation based solids velocimetry, and proved that the cross-correlation algorithm is ideal for solids convection-dominated systems or regions in a system, but caution is needed when solids mixing is important.