Mixing in large scale storage tanks: Studies on the boundary layer thickness at the base of storage tanks agitated with side-entry propellers

Abstract

Studies of the thickness of the viscous sub-layer and its distribution around the base of a tank fitted with a sideentry propeller has been studied by simulating the process on a 1.2m diameter tank. An electro-chemical technique has been employed to study the thickness of the viscous sublayer and the effect of impeller speed, impeller diameter, shaft angle, liquid depth, and physical properties of the solution on this thickness. Also a hot-film anemometer was used to check and compare the results obtained by the electro-chemical technique and it was found that both were in agreement. However, the results obtained by the electrochemical technique gives an indication of the effec of the diffusivity and the thickness of the viscous sub-layer was related to both Reynolds number and Schmidt number. A mathematical model has been developed to describe the velocity distribution along the impeller jet and to predict the thickness of the viscous sub-layer along the jet. The results obtained from this model agree with those obtained by experiment. Studies on minimizing the thickness of the viscous sublayer showed that the presence of one or more small baffles on the base of thetank help to lift the sediments into the bulk of the solution. Finally, full-scale measurements were carried-out on 79m diameter tank to provide data for scale-up.

Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
Additional Information: Copyright © Ghassan Hassan Al-Hassani, 1977. Ghassan Hassan Al-Hassani asserts his moral right to be identified as the author of this thesis. This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without appropriate permission or acknowledgement. If you have discovered material in Aston Publications Explorer which is unlawful e.g. breaches copyright, (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our Takedown Policy and contact the service immediately.
Institution: Aston University
Uncontrolled Keywords: Side-entry mixing,large scale storage tanks,boundary layer thickness
Last Modified: 08 Dec 2023 08:07
Date Deposited: 28 Oct 2019 15:41
Completed Date: 1977-11
Authors: Al-Hassani, Ghassan Hassan

Export / Share Citation


Statistics

Additional statistics for this record