气固两相在循环流化床传质过程中的计算传质学方法研究

Gas-particle two-phase mass transfer in circulating fluidized bed has been widely applied in industry. To reveal the mass transfer characteristics and predict rigorously the mass transfer process are of great importance for the development of mass transfer theory, the enhancement of industrial process efficiency and the development of novel efficient equipment. In this proposal, it is to study the mass transfer process in gas-particle circulating fluidized bed (CFB) by carrying out experiments and simulations, and establish computational mass transfer method for the mass transfer process in gas-particle CFB thereafter. To investigate the heterogeneity of gas-particle flow structure, including the forming and movement of particle clusters, by cold-model experiments; to investigate the mass transfer behavior and the mass transfer characteristics by hot-model experiments; to reveal the anisotropy of turbulent mass diffusion and the coupling effect among the species concentration distribution and the gas-particle flow field as well as the anisotropic turbulent mass diffusion. And then, to explore the simulation method for the gas-particle two-phase transport process by research on modeling; to establish rigorous mathematical model so that the species concentration and the gas-particle velocity can be simultaneously predicted. The aim of the research including further development of computational mass transfer theory and deeper understanding of gas-particle two-phase mass transfer phenomena in circulating fluidized bed.

循环流化床中气固两相的传质过程有着非常广泛的工业应用，揭示其传质特性以及准确预测其传质行为，对完善传质理论、提高工业装置效率、开发新型传质设备都有重要的意义。本项目针对循环流化床内气固两相传质过程开展实验与模拟研究，进而提出气固两相在循环流化床传质过程中的计算传质学方法。首先，对气固两相流动中的非均匀结构—“颗粒团聚物”（particle cluster）的形成与运动开展实验研究，探索颗粒团聚物的结构特性及其对气固两相流动的影响；研究气固两相流动中的传质过程及其传质特性，探索湍流条件下组分扩散的各向异性以及浓度分布与流体流动的耦合关系。然后，通过建模、模拟研究，探索气固两相在循环流化床中流动、传质过程的预测方法，建立相应的数学模型，实现流化床内气固两相流速分布、组分浓度分布的准确预测，最终进一步完善计算传质学理论，深入了解循环流化床气固两相传质现象。