Scale-up criteria for obtaining the same vertical concentration profile of particles in agitated, dilute suspensions are considered. Previous experiments in two sizes of high aspect ratio vessels stirred by multiple impellers (either pitched blade or Rushton turbines) gave n=0.93 in the scale-up relationship36 NDn=constant. This result is intermediate between constant power per unit volume (n=2/3) and constant tip speed (n=1), although closer to the latter. It is now suggested that intermittent turbulent fluctuations greater than their average values play a part in maintaining vertical concentration gradients. An analysis of solids suspension by intermittent turbulence gives n»0.93. This value is also supported by additional experimental data as well as by new CFD results.

Scale-up of solids distribution in slurry, stirred vessels based on turbulence intermittency

MONTANTE, GIUSEPPINA MARIA ROSA;MAGELLI, FRANCO
2008

Abstract

Scale-up criteria for obtaining the same vertical concentration profile of particles in agitated, dilute suspensions are considered. Previous experiments in two sizes of high aspect ratio vessels stirred by multiple impellers (either pitched blade or Rushton turbines) gave n=0.93 in the scale-up relationship36 NDn=constant. This result is intermediate between constant power per unit volume (n=2/3) and constant tip speed (n=1), although closer to the latter. It is now suggested that intermittent turbulent fluctuations greater than their average values play a part in maintaining vertical concentration gradients. An analysis of solids suspension by intermittent turbulence gives n»0.93. This value is also supported by additional experimental data as well as by new CFD results.
G. Montante; J.R. Bourne; F. Magelli
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/63692
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 13
  • ???jsp.display-item.citation.isi??? 12
social impact