Fluidization dynamics of cohesive Geldart B particles. Part I

Fluidization dynamics of cohesive Geldart B particles. Part I: X-ray tomography analysis

Ma, Jiliang (Southeast University)
van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)
Liu, Daoyin (Southeast University)
Mudde, R.F. (TU Delft ImPhys/Imaging Physics; TU Delft Executive board)
Chen, Xiaoping (Southeast University)
Wagner, E.C. (TU Delft ChemE/Afdelingsbureau)
Liang, Cai (Southeast University)

ImPhys/Imaging Physics

2019

Due to the presence of inter-particle cohesive force, cohesive particles reveal totally different fluidization behaviors as compared to the non-cohesive system. This paper studies the fluidization dynamics of Geldart B particles with varying thermal-induced cohesive forces. Multi-source X-ray tomography was applied to reconstruct 3D temporal images of bubbles, based on which, various bubble properties were extracted. The results show that increasing cohesive force will decrease bubble number while increase bubble size, implying that the presence of cohesive force facilitates bubble coalescence. By examining the bubble size distribution, cohesive force is found to have no effect on the number of median bubbles but greatly influence small and large bubbles. When the cohesive force is strong, the bubbles grow to a considerable size similar with bed dimension, giving rise to slugging near bed surface. With the action of inter-particle cohesive force, particle slug gradually grows by capturing other freely fluidizing particles, finally inducing “whole-bed” slugging. The particle slug may rupture in the rising process, and the bed turns back to normal fluidization. In comparison to normal bubbles, the gas slug has much larger size but far smaller frequency. The rise velocity of gas slug is also very low due to the particle-wall friction and gas-solid momentum dissipation. Therefore, the averaged values of bubble properties dramatically changed as bed temperature exceeds 35 °C. When the temperature attains 45 °C, the cohesive force is so strong that the fluidization completely fails in terms of stable whole-bed slugging.

Bubble
Cohesive particle
Fluidization
Slugging
X-ray tomography

http://resolver.tudelft.nl/uuid:11523521-351a-44e6-802a-34e4c40ccd22

https://doi.org/10.1016/j.cej.2018.11.082

2019-05-12

1385-8947

Chemical Engineering Journal, 359, 1024-1034

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2019 Jiliang Ma, J.R. van Ommen, Daoyin Liu, R.F. Mudde, Xiaoping Chen, E.C. Wagner, Cai Liang