Three-dimensional CFD simulation and experimental validation of particle segregation in CFB riser

Abstract

Purpose The purpose of this paper is to perform the computational fluid dynamics (CFD) simulation with experimental validation to investigate the particle segregation effect in abrupt and smooth shapes circulating fluidized bed (CFB) risers. Design/methodology/approach The experimental investigations were carried out in lab-scale CFB systems and the CFD simulations were performed by using commercial software BARRACUDA. Special attention was paid to investigate the gas-particle flow behavior at the top of the riser with three different superficial velocities, namely, 4, 6 and 7.7 m/s. Here, a CFD-based noble simulation approach called multi-phase particle in cell (MP-PIC) was used to investigate the effect of traditional drag models (Wen-Yu, Ergun, Wen-Yu-Ergun and Richardson-Davidson-Harrison) on particle flow characteristics in CFB riser. Findings Findings from the experimentations revealed that the increase in gas velocity leads to decrease the mixing index inside the riser. Moreover, the solid holdup found more in abrupt riser than smooth riser at the constant gas velocity. Despite the more experimental investigations, the findings with CFD simulations revealed that the MP-PIC approach, which was combined with different drag models could be more effective for the practical (industrial) design of CFB riser. Well agreement was found between the simulation and experimental outputs. The simulation work was compared with experimental data, which shows the good agreement (<4%). Originality/value The experimental and simulation study performed in this research study constitutes an easy-to-use with different drag coefficient. The proposed MP-PIC model is more effective for large particles fluidized bed, which can be helpful for further research on industrial gas-particle fluidized bed reactors. This study is expected to give throughout the analysis of CFB hydrodynamics with further exploration of overall fluidization.

CFD-DEM coupled simulation of fluidized beds with improved lumped formulation for heat transfer

“…Local averaged variables are used in the conservation equations, which are, in turn, resolved through computational fluid dynamics (CFD). Due to its reasonable computational cost for practical application problems, the TFM is currently the most used approach for modeling fluidization processes (Gidaspow, 1994; Venier et al , 2020; Dwivedi et al , 2020). However, besides being unable to provide individual particle flow information, the capacity of a continuous approach to producing good results is directly dependent on constructing constitutive relations for the stress tensor and the effective conductivity of the solid phase (Peng et al , 2020), which has been proven quite challenging.…”

Experimental study of solid circulation rate and pressure distribution characteristics in a cold fluidized bed with an external heat exchanger in an municipal solid waste incinerator

“…The latter mainly studies heat transfer characteristics by changing operating parameters such as fluidized air velocity, pressure, and particle diameter. 16 In recent years, the cold experiment and numerical simulation research on CFB mainly focus on the riser [17][18][19][20][21] ; many test rigs and models do not design EHEs but simple loop seals. [22][23][24] Xiong has developed a new type of cold EHE text rig that is adjusted by pneumatic and an empirical formula for SCR, and pressure across an orifice has been proposed.…”