Using Tomography to Characterize the Mixing of Non-Newtonian Fluids with a Maxblend Impeller

• Published in: Chemical engineering & technology Vol. 36; no. 4; pp. 687 - 695
• Main Authors: Patel, D., Ein-Mozaffari, F., Mehrvar, M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-04-2013; WILEY‐VCH Verlag
• Subjects: Batch mixing; Electrical resistance tomography; Fluid dynamics; Fluid flow; Fluids; Impellers; Maxblend impeller; Non Newtonian fluids; Power consumption; Tomography; Vessels; Yield stress
• ISSN: 0930-7516; 1521-4125
• DOI: 10.1002/ceat.201200425

The flow field inside a cylindrical mixing vessel was visualized by electrical resistance tomography (ERT), a non‐intrusive measurement technique. Six tomography planes, each containing 16 sensing electrodes, measured the mixing time in the agitation of pseudoplastic fluid exhibiting yield stress. The effects of various parameters such as impeller types, impeller speed, fluid rheology, power consumption, Reynolds number, and absence of baffles on the mixing time were investigated. The Maxblend impeller was able to improve the mixing performance of non‐Newtonian fluids in a batch reactor. The mixing quality could be further enhanced by decreasing the xanthan gum concentration and using baffles in the mixing vessel.
Mixing of non‐Newtonian fluids with yield stress in a stirred vessel was evaluated by electrical resistance tomography. The mixing performance of different impellers was determined via mixing time and specific power consumption. A Maxblend impeller was found to be most efficient in terms of uniform mixing in a shorter time and with lower power input.