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Analysis of Regime Transitions and Flow Instabilities in Vertical Conveying of Coarse Particles Using Different Solids Feeding Systems
Author(s) -
Costa Ione A.,
Do Carmo. Ferreira Maria,
Freire José T.
Publication year - 2004
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450820107
Subject(s) - mechanics , choking , pressure gradient , particle (ecology) , materials science , flow (mathematics) , gravitational force , two phase flow , thermodynamics , physics , geology , classical mechanics , medicine , oceanography , anatomy
Abstract The transition between dense and dilute flow in vertical conveying of Geldart D particles were investigated for risers of different diameters using a spouted bed as a solid feeding system. The transition and choking velocities were identified by combining analyses of pressure gradient versus air velocity diagrams, pressure fluctuation signals and voidage values. Experimental data were used to evaluate the effect of particle and riser diameters on the pressure gradient, mean mixture voidage, the regime transition and choking velocities. The transition velocity from dilute to dense phase could be identified, as well as the onset of the choking condition, which appeared as the air velocity was further reduced. Data obtained in the same experimental apparatus facility using a screw conveyor and a gravitational system as solid feeding devices have been used as a reference to be compared to those obtained using the spouted bed feeder.