Instantaneous mixing characteristics of binary mixtures differing in density in a gas-solid fluidised bed

作     者：Zhen Wan Youjun Lu Hao Wang Zhen Wan;Youjun Lu;Hao Wang

作者机构：State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049ShaanxiChina 

出 版 物：《Particuology》 (颗粒学报（英文版）)

年 卷 期：2020年第18卷第6期

页      面：63-71页

核心收录：

学科分类：08[工学] 080103[工学-流体力学] 0817[工学-化学工程与技术] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0801[工学-力学（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：the National Nature Science Foundation of China through contract No.51925602 No.51888103 and No.51676158. 

主　　题：Binary mixtures Fluidised bed Mixing Instantaneous characteristics 

摘      要：Characterisations of instantaneous mixing behaviours in fluidised beds with binary mixtures has many challenges.We studied the instantaneous mixing characteristics of binary mixtures in a 2-D quasi gas-solid fluidised bed using a capacitance probe method.This method enabled the quantitative assessment of instantaneous mixing behaviours,including mixing index,rate,and time.Three kinds of binary mixtures of similar size but different density were used for the transient and steady fluidisation experiments in a bubbling fluidised bed.The mixing curves of initially segregated binary mixtures were acquired,and the instantaneous characteristics for the entire process were analysed.An equation was proposed to describe the mixing process and predict the mixing degree over time.By comparing experiments with different working conditions,the effects of superficial gas velocity and density ratio on the mixing in the centre and at the wall of the fluidised bed were addressed.During the stable fluidisation stage,the axial concentration profiles of the mixtures were obtained,and the mechanisms of mixing were discussed.Results showed that the mixing level increased logarithmically with time and eventually reached a relatively stable value.Increasing the superficial gas velocity and reducing the density ratio promoted mixing and reduced mixing time.High superficial gas velocities tended to mix the mixtures well and quickly,regardless of the density ratio of the two components.