Predictive model for segregation of broad particle size distributions in turbulent fluidized beds based on experimental investigation

Abstract

Circulating fluidized beds (CFBs) play a significant role in a variety of industrial processes due to continuous solids circulation, high mixing efficiency and stable operation over a wide range of operating conditions. These parameters become particularly important for adapting CFB technology to applications involving broad particle size distributions (PSD), such as hydrogen-based direct reduction of iron ore fines, where gas–solid contact efficiency and solids segregation are influenced by hydrodynamic behavior. In this study, cold flow model experiments were conducted to establish hydrodynamic similarity to a laboratory-scale CFB reactor. Two bed materials with different particle size characteristics were selected: the first replicated commercial iron ore fines and the second was shifted toward coarser particles to examine the influence of PSD. Measurements included reactor pressure profile, PSD along the reactor height, solids holdup and solids circulation rates. The experimental results show that superficial gas velocity and PSD of the bed material influence solids entrainment and segregation patterns. Based on the experimental data, a predictive model was developed to estimate particle segregation in turbulent fluidized bed reactors with broad PSDs using the initial PSD of the bed material. This approach provides an experimentally validated framework for quantifying segregation effects in CFB reactors and supports reactor design and scale-up to high-temperature processes involving broad PSDs.