SILVA, O. S.; http://lattes.cnpq.br/6441275307028933; SILVA, Osvaldo Soares da.
Résumé:
The importance of the knowledge about fluid dynamics of spouted beds
constituted by mixture of particles is apparent in a number of process in the
chemical pharmaceutical industry and food technology. The dehydration of pulps
and suspensions, the obtention of a blxine concentrated powder by attrition of
annafto seeds( Bixa Qreiiana L), are examples. When particles of diameter in
the order of 100um; whom we will call "entrainable" are present in the bed of
spoutabies particles, the mechanisms of circulation are different of those in the
conventional spouted bed. As the spoutable and a part of the entrainable
particles circulate in the bed, an other part of the fines is trained and captured by
the cyclone and the rest accumulate fluidizing at the top of the annulus.
Although there are some studies about the fluid dynamics of beds with a mixture
of particles with diameters of the same magnitude, works about the behavior of
these type of systems when constituted by particles with great differences in
size, are scarce, in previous work the effect of the presence of the powder,
obtained by the attrition of the seeds, over the fluid dynamics of a spouted bed of
annafto seeds was analyzed. Is this work, the results were extended to différents
mass ratio of fine to coarse particles . A synthetic system of polypropylene and
maize flour was also studied for comparison. An important influence of the fines
proportion over the circulation characteristics and fluid dynamics parameters
were verified. The characteristics curves were followed by the partial
entraînement of the fines. It was observed that the APmâ* is decreased and APim
is augmented with the increasing of the entrainable particles proportion.
Nevertheless no influence of the fines over the Uim was detected.
