Influences on the transition from bubbling to turbulent fluidization for Geldart's group B particles

A detailed study of parameters influencing the transition from bubbling to turbulent fluidization was done. The transition velocity U-c was determined by pressure fluctuation analysis for different size fractions of sand and ilmenite particles (Geldart's group B). Four different plants (laboratory and pilot scale) were used having diameters ranging from 0.05 m to 0.4 m. The static bed height was varied, resulting in aspect ratios (static bed height/bed diameter) from 1 to 4. The results of U-c show a clear dependency of aspect ratio, bed diameter, temperature and partide size. The diameter of the bed was found to influence the transition velocity especially in small fluidized beds. The static bed height has a significant influence on the transition velocity which has to be considered in scale-up. As a further parameter, the temperature influence was investigated up to 800 degrees C. No correlation in literature was found to predict satisfactorily the influences of the parameters investigated. (C) 2020 Elsevier B.V. All rights reserved.