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PEPT study of particle cycle and residence time distributions in a W urster fluid bed
Author(s) -
Li Liang,
Rasmuson Anders,
Ingram Andy,
Johansson Mats,
Remmelgas Johan,
Corswant Christian,
Folestad Staffan
Publication year - 2015
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.14692
Subject(s) - residence time (fluid dynamics) , residence time distribution , particle (ecology) , tracking (education) , mechanics , materials science , physics , engineering , flow (mathematics) , geology , psychology , pedagogy , oceanography , geotechnical engineering
Particle cycle and residence time distributions are critical factors in determining the coating quality in the Wurster process. Positron emission particle tracking experiments are performed to determine the cycle and residence times of particles in different regions of a Wurster fluid bed. The results show that particles tend to recirculate in and sneak out below from the Wurster tube. The experiments also show that a larger batch size leads to a shorter cycle time and a narrower cycle time distribution (CTD). It is possible to avoid recirculations and obtain a shorter cycle time and a narrower CTD by selecting the operating conditions appropriately or via equipment design. Experiments using binary mixtures of particles with a diameter ratio of 1.5 show that large particles have a longer cycle time than small particles and that the cycle time is shorter for mixtures with approximately equal amounts of small and large particles. © 2014 American Institute of Chemical Engineers AIChE J , 61: 756–768, 2015