Fluidized beds are widely used in many industrial processes as they ensure the desirable high-intensity heat and mass transfers between gas and particles and offer the possibility to perform operations in a continuous mode and powders recycling. Some of these industrial processes use Geldart D type of powders and operate in the slugging mode. This paper presents a 3 D numerical model of gas-solid flows in a fluidized bed based on the Two-Fluid Model (TFM). Turbulence modeling (k- ε) was used to predict flow behavior in fluidized bed of Geldart D particles. The solid phase consists of Geldart D powders and the gas flow is in a slug regime. The numerical results are validated against the experimental work of Azzi et al. Model predictions on flow patterns, bed expansion, volume fraction time series and pressure drop fluctuations are presented and discussed in details in order to demonstrate the cyclic process of slug formation (onset, growth, rising and bursting of slugs) and its effects on the overall performance of beds fluidizing Geldart D type of powders.

流化床被广泛用于许多工业过程，因为它们确保了气体和颗粒之间所需的高强度传热和传质，并提供了以连续模式进行操作和粉末回收的可能性。这些工业过程中的某些过程使用Geldart D型粉末并以团块模式运行。本文提出了基于两流体模型（TFM）的流化床中气固两相流的3D数值模型。湍流模型（k-ε）用于预测Geldart D颗粒流化床中的流动行为。固相由Geldart D粉末组成，气流呈团状状态。数值结果与Azzi等人的实验工作进行了验证。流动模式，床层扩展，