CFD simulation of solids residence time distribution for scaling up gas‐solid bubbling fluidized bed reactors based on the modified structure‐based drag model. (3rd November 2020)

• Record Type: Journal Article
• Authors: Zhao, Yunlong; Zou, Zheng; Wang, Junwu; Li, Hongzhong; Zhu, Qingshan
• Is Part Of: Canadian journal of chemical engineering. Volume 99:Number 8(2021)
• Page Start: 1780
• Page End: 1791
• Publication Date: 2020-11-03
• Subjects: BFB -- computational fluid dynamics -- fluidization -- residence time distribution -- scale‐up; Chemical engineering -- Periodicals; Technology -- Periodicals; 660.05
• DOI: 10.1002/cjce.23882
• Languages: English
• ISSNs: 0008-4034

Abstract

Abstract: Solids residence time distribution (RTD), which reflects the degree of solids mixing in bubbling fluidized bed (BFB), has become an essential parameter for the evaluation of reactor performances. In this paper, a modified structure‐based drag model was established to investigate the effect of the bed size and the correlation of bubble dimension on the gas‐solids hydrodynamics and solids RTD in three different scales of BFB. The result obtained from the modified structure‐based drag model shows better agreement with the experimental values and it can be used to predict the RTD properly. The deviation of flow field will cause a large difference in the RTD prediction. An accurate flow field is a prerequisite for calculating the RTD. For the cases of Geldart B particles, the Darton correlation is the best choice for low gas velocities. When scaling up a BFB, the RTD calculated by the modified structure‐based drag model is reduced in comparison with the experimental value, which is related to the increase of the bed size and the excessive estimation of the bubble size. On the other hand, the lack of consideration for the friction on both front and back walls in 2D simulation may lead to the over‐prediction of particle velocity and result in the deviation between calculated and experimental RTD value.