Computational fluid dynamics simulation of hydrodynamics in an internal-loop fluidized bed reactor with a funnel-shaped internal
基于CFD的内构件强化内循环流化床流场结构分析

The development of fluidized bed reactors suffers from drawbacks including a poor understanding of the complexity of internal fluid flow and the lack of an efficient theory for scale-up of the design. A computational fluid dynamics (CFD) simulation using the Eulerian-Eulerian double-phase model was used for predicting the complex two-phase flow in a reactor which was enhanced by implanting an funnel-shaped internal in the internal-loop fluidized bed reactor. The role of the conical baffle in improving the gas-liquid mixing was explored by investigating the flow field, the gas holdup distribution and the liquid velocity distribution. The simulation results demonstrate that the Eulerian-Eulerian model reasonably predicts the two-phase flow in the fluidized bed. The cone-shaped baffle is favorable for improving gas-liquid mass transfer by increasing the flow conductivity of both gas and liquid and extending the bubble retention time. The presence of the conical baffle results in an increase in the gas holdup by 10%~25% in the rising area and by a maximum of ten times in the downcomer area, but also a noticeable decrease in the liquid circulation velocity. Non-uniform distribution of bubbles is also observed in the downcomer area, and specifically the gas holdup in some areas is found to approach 1. The simulation results imply that the appropriate range of gas velocity and type of the implanted baffle should be rationalized to achieve the optimal liquid circulation velocity and gas holdup, thus leading to the optimization of reactor function and system design.