Scale-up of bubbling fluidized beds with continuous particle flow based on particle-residence-time distribution--颗粒学报PARTICUOLOGY

Zhang, J., & Xu, G. (2015). Scale-up of bubbling fluidized beds with continuous particle flow based on particle-residence-time distribution. Particuology, 19, 155–163. https://doi.org/10.1016/j.partic.2014.04.019

Scale-up of bubbling fluidized beds with continuous particle flow based on particle-residence-time distribution

Juwei Zhang^*, Guangwen Xu^*

State Key Laboratory of Multi-phase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China

10.1016/j.partic.2014.04.019

Volume 19, April 2015, Pages 155-163

Received 29 November 2013, Revised 14 April 2014, Accepted 15 April 2014, Available online 12 October 2014.

E-mail: juwei.zhang2013@gmail.com; juwei_zhang@ihi.co.jp

Highlights

• It was possible to obtain similar RTDs in geometrically similar bubbling fluidized beds.

• A simple scaling method was proposed without need of changing particle size and gas velocity.

• RTDs of BFBs at different scales could be predicted by using the simple scaling method.

Abstract

Few studies have investigated scale-up of the residence-time distribution (RTD) of particles in bubbling fluidized beds (BFBs) with continuous particle flow. Two approaches were investigated in this study: first, using well-known scaling laws that require changes in particle properties and gas velocity; second, using a simple approach keeping the same particles and gas velocity for different beds. Our theoretical analysis indicates it is possible to obtain similar RTDs in different BFBs with scaling laws if the plug-flow residence time (t_plug) is changed as m^0.5, where m is the scaling ratio of the bed; however, neither approach can ensure similar RTDs if t_plug is kept invariant. To investigate RTD variations using two approaches without changing t_plug, we performed experiments in three BFBs. The derivatives dE(θ)/dθ (where E(θ) is the dimensionless RTD density function and θ is the dimensionless time) in the early stage of the RTDs always varied with m⁻¹, which was attributed to the fact that the particle movement in the early stage were mainly subject to dispersion. Using the simple approach, we obtained similar RTDs by separately treating the RTDs in the early and post-stages. This approach guarantees RTD similarity and provides basic rules for designing BFBs.

Graphical abstract

Keywords

Bubbling fluidized bed (BFB); Scale-up; Residence time distribution (RTD; Similarity

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