Investigation of hydrodynamics of binary fluidized beds via radioactive particle tracking and dual‐source densitometry

The mixing and hydrodynamic behaviour of binary fluidized beds of particles of same size and differing density has been investigated experimentally by using radiation based non-invasive techniques, viz. radioactive particle tracking (RPT) and dual-source densitometry. The effect of air inlet velocity and bed composition has been investigated. RPT experiments are performed individually for both the solids by tracking one particle at a time. Many interesting findings are discussed, for example, such as the heavier (jetsam) phase is seen to be fluidized by action of the lighter (flotsam) phase even below its minimum fluidization velocity. Further, it has been found that while with increase in air inlet velocity, the extent of mixing of solid phases increases; even at very high air velocities the jetsam phase is not completely mixed. The important role played by the particle–particle collisions in the fluidization of binary mixtures is quantitatively highlighted. Le melange et le comportement hydrodynamique des lits fluidises binaires de particules de meme taille et de differentes densites ont ete etudies experimentalement en utilisant une technique non invasive a base de rayonnements par le suivi des particules radioactives et la densitometrie a double foyer. L'effet de la vitesse d'admission d'air et de la composition du lit a ete etudie. Des experiences de suivi des particules radioactives sont executees individuellement pour chacun des deux solides par le suivi d'une particule a la fois. Plusieurs resultats interessants sont discutes, comme par exemple, il est observe que la phase plus lourde (jetsam) est fluidisee par l'action de la phase plus legere (flotsam), meme en dessous de sa vitesse minimum de fluidisation. De plus, il a ete constate que, tandis qu'avec l'accroissement de la vitesse d'admission d'air, l'ampleur du melange des phases solides augmente, la phase jetsam n'est pas completement melangee meme a des vitesses d'air tres elevees. Le role important joue par les collisions particule-particule dans la fluidisation des melanges binaires est quantitativement mis en evidence.

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