ETD system

Electronic theses and dissertations repository

 

Tesi etd-11242003-180447


Thesis type
Tesi di laurea vecchio ordinamento
Author
Chiti, Fabio
email address
fabio.chiti@tiscali.it
URN
etd-11242003-180447
Title
Analisi Fluodinamica di Reattori Bifase Gas-Liquido
Struttura
INGEGNERIA
Corso di studi
INGEGNERIA CHIMICA
Commissione
relatore Prof. Paglianti, Alessandro
Parole chiave
  • Fluidodinamica
  • Reattori Agitati
  • Cleaning Aluminium
  • 3PBT30
  • Mixing
Data inizio appello
11/12/2003;
Consultabilità
parziale
Data di rilascio
11/12/2043
Riassunto analitico
The furnace treatment is an important step during molten aluminium production, by which the dissolved hydrogen and solid impurity particles were removed. Conventionally, a chlorine/inert gas mixture is used for this purpose. However the potential leakage of chlorine and chemical reaction produce hydrogen chloride considered to be dangerous to society and faces the restriction in the new clean air regulation. So, in order to meet the requirement for the furnace emission and improve efficiency, mechanical agitation through impeller was widely used. In this research, the homogenization behaviour of both lance bubbling and mechanical agitation through two different impellers has been investigated experimentally (power drawn, decolourusation, PIV) and numerically. At equivalent mean specific energy dissipation rates, maximum velocities are higher and mixing times are shorter with the impellers, without to cause surface gas entrainment, the latter being detrimental to fluxing. Two different impellers have been analysed because one is designed to resist at high temperature, STAS, and its material (graphite) does not allow a standard shape, so it was necessary to compare its performance with a standard impeller, 3PBT30. In conclusion, the STAS impeller has been considered a good solution for this kind of cleaning process, in fact, despite the strange shape (very thick blades), the impeller shows nice properties like a standard impeller, 3PBT30. Furthermore very interesting results have been obtained in mixing time using asymmetrical configurations, reducing the mixing time more than 20%.
File