Resumo (PT):
Abstract (EN):
This paper addresses the experimental validation of the optimum design of
reverse-flow gas-cyclones, obtained through the solution of a numerical non-linear
optimization problem, viz. maximizing cyclone collection. The simulation model is
based on the predictive properties of a finite diffusivity model, where the particles’
turbulent dispersion coefficient is estimated through an empirical correlation between
the radial Peclet and Reynolds numbers. The optimizations were formulated with
constraints on pressure drop, saltation velocity and geometrical considerations, such
that feasible cyclones could always be obtained.
The optimum geometry, named RS_VHE, is different from available highefficiency designs, and represents reverse-flow cyclones with a predicted
significantly improved performance. An innovative partial recirculation system within
a collector-first arrangement further reduces emissions with only a moderate
increase in pressure drop. The generally observed unexpected high collection of
submicron particles is attributed to capture by larger particles in the turbulent flow
field due to turbulent dispersion, much like what occurs in re-circulating fluidized
beds.
Results obtained for the RS_VHE cyclones with partial recirculation at laboratory,
pilot and industrial scales, for temperatures ranging from 300 to 600 K, gas flow
rates from 1 to 104 m3
/h and inlet loads from 15 to 104 mg/m3
, show them to be
significantly more performing than equivalent diameter HE cyclones or smaller
diameter multi-cyclones. Under certain circumstances, with recirculation the
proposed system shows better performance than on-line pulse-jet bag-filters.
Overall, the results show that the numerically optimized RS_VHE cyclones, when
coupled with a partial recirculation system, open the applicability of these simple
devices for fine particle collection which is typical of more expensive devices, such
as venturis and on-line pulse-jet bag-filters.
KEYWORDS : optimized gas cyclones, recircul
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
6