连续进出料鼓泡流化床停留时间分布的相似准则研究

Particles residence time distribution (RTD) in bubbling fluidized beds is important for its performances, and the evaluation of particles RTD in large-scale bubbling fluidized beds is a critical issue. In this study, a diffusion criteria number was introduced based on the scaling law proposed by Glicksman. Then the fluidized bed similarity scaling law that exhibits RTD similarity was obtained, and the transformation relations for the similarity of particles RTD was clarified. The flow behaviors and particles RTD of the scaled-down and original fluidized beds were numerically simulated. The results show that within the specific range of geometric similarity constants (1 < k < 200), the computational time for the scaled-down model could be reduced from 22.8 days to 1.4 days. Moreover, the particles RTD exhibits similarity to that of the original bed, with a maximum error not exceeding 9.24%. Following the similarity transformation, the particles RTD of the scaled-down model demonstrates a favorable ability to predict the particles RTD of the original bed, with a maximum error for key characteristic values of 17.8%. Furthermore, variations in particle flow rate, fluidization velocity, and static bed height do not influence the accuracy of scaled-down model in predicting the particles RTD of the original bed. The maximum error of its key characteristic values does not exceed 10.32%. This confirms the applicability of the similarity scaling law under varying operating conditions. All the results demonstrate the effective of presented similarity scaling law for the rapid and accurate prediction of particles RTD in large-scale fluidized beds.