Mixing efficiency in stirred tanks is an important consideration in the design of many industrial processes. Computational fluid dynamics (CFD)
techniques have been employed in the present work to study the hydrodynamics in a tank stirred by a Rushton turbine. The effect of the impeller
clearance on the velocity field and mixing has been investigated. It has been shown that at a low impeller clearance, the Rushton turbine generates
a flow field that evolves from the typical two loops to a single loop flow pattern similar to that of an axial impeller. This single loop flow pattern
resulted in an increase in axial flow and a decrease in mixing time at a constant power number. It has been found that a draft tube can be used with
a single Rushton turbine, at a low clearance to aid axial flow and mixing, and this resulted in 50% reduction in mixing time. There was a good
comparison between laser Doppler velocimetry (LDV) experimental and CFD simulation flow fields, both of which showed that the draft tube
improved mixing in the tank by suppressing secondary circulation loops.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1000754 |
| Date | January 2008 |
| Creators | Ochieng, A, Onyango, MS, Kumar, A, Kiriamiti, K, Musonge, P |
| Contributors | Chemical Engineering and processing |
| Publisher | Elsevier |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Source | Research article |
| Rights | Elsevier |
| Relation | Chemical Engineering and Processing |
Page generated in 0.0025 seconds