Experimental Investigation And Numerical Simulation On Hydrodynamic Characteristics In Gas-Liquid-Solid Fluidized Beds

By far, the simple and effective measurement techniques to detect the local gasphase, liquid phase and solid phase holdups simultaneously, the three-phase datapublished in open literature and the mathematic models for describing three-phaseflow behaviors accurately are scarcely due to the complexity of gas-liquid-solidflows. The academic research and industrial application are restricted by thissituation. Therefore, it is necessary to develop some effective measuring methods oflocal three-phase holdups. At the same time, it is an important task to obtain a greatdeal of useful experimental data and to establish the three-phase turbulent flowEulerian/ Eulerian / Eulerian (E/E/E) model.The paper presents a review of the references on the developments of totalhydrodynamic behaviors, multi-phase flow detecting techniques and multi-phaseflow models and numerical simulation. The direction for future study in this field isindicated on the basis of above analysis.Secondly, the micro-electrical conductivity probe detecting technique is appliedto measure local three-phase holdups simultaneously on the basis of the pilot studyat research institute. The earlier detecting method is consummated.Thirdly, Sets of more 5000 experimental data are gained by using themicro-electrical conductivity probe detecting technique under wider experimentalconditions in conventional fluidized beds and circulating fluidized beds. Somecorrelations are established on the basis of experimental data. It can be noted thatlocal solid holdup has had a maximum peak at r/R=0.75～0.85 in fully fluidizationregion of conventional fluidized bed. In gas distributor region, three-phase localholdups in radial direction exist badly asymmetry distribution. The local gas holdupand solid holdup are influenced on liquid viscosity in gas-liquid-solid inverseturbulent bed (GLSITB). The range of maximum peak is enlarger than higherdensity particles system. The local gas holdup and solid holdup are more flatnessand particle circulating rate increases with increasing liquid viscosity in riser ofgas-liquid-solid circulating fluidized bed (GLSCFB). The regime map is extendedby using results of onset liquid velocity and transition liquid velocity under differentfluid viscosity and lower density particle.Fourthly, E/E/E model for GLS three-phase local flow is established through avertical column by analyzing three-phase flow characteristics on the basis of newcorrelations. Computational fluid dynamics (CFD) implementing a multi-fluidmodel with RNG k-ε turbulent model and special momentum exchange terms fordirect gas-solid interactions is adopted to numerical simulate the local phasehold-ups in GLSFB and GLSCFB. The solution is accomplished by using Fluent6.0commerce software and finite volume method for discrete format. The model is alsotested with the experimental data. It is noticed that the model predictions are inclose agreement with the experimental data. The applicability and reliability of themodel are validated.