建立了工业尺度数值试验的过热蒸汽/热载体/生物质三相欧拉数理模型。水蒸气设为主连续相,采用k-ε方程描述;热载体和生物质设为两种不同的拟流体相,其黏度和压力采用颗粒动理论方程进行封闭;气固相互作用力采用Symbol-O'Brein曳力模型描述,固固之间作用力采用morsi-alexander模型描述;气固之间传热采用Gunn模型描述。基于该模型的数值试验,实现了喷动流化床混合器的优化设计使热载体与生物质的混合程度达70%以上;并研究了物料性质对生物质终温的影响,生物质终温受生物质粒径的影响最为显著。
A three-dimensional Eulerian-Eulerian multiphase model(two-fluid model,TFM) was developed to simulate the three-phase mixing behaviors of superheated steam,heat-carrier and biomass particles in an industrial-scale spout-fluid bed mixer.The superheated steam was treated as continuous primary phase simulated by the k-ε two-equation turbulent model,while the heat-carrier and biomass were treated as two different secondary phases,and their viscosities and pressures were provided by the Kinetic theory of granular flow.The interactions between gas phase and each solid phase are described by Symbol-O'Brein drag model,while the interaction between two solid phases is described by morsi-alexander model.Heat transfers between gas phase and solid phases were calculated by Gunn model.Based on above models,the mixing effectiveness of the mixer was valuated and the effects of material properties on the heat transfer between phases were numerically investigated.Results show that the mixing effectivenss of spout-fluid mixer can reach over 70%and the final temperature of biomass is most sensitive to the size of biomass particle.