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Scale formation on the wall of a mechanically stirred vessel—experimental assessment and interpretation using computational fluid dynamics
Author(s) -
Davoody Meysam,
Lane Graeme,
Graham Lachlan J. W.,
Wu Jie,
Madapusi Srinivasan,
Parthasarathy Rajarathinam
Publication year - 2018
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16358
Subject(s) - computational fluid dynamics , mechanics , impeller , fluid dynamics , scale (ratio) , flow (mathematics) , turbulence , materials science , chemistry , physics , quantum mechanics
Accelerated growth of scale was studied in a baffled agitated reactor, which could be disassembled into nine sections, allowing quantitative determination of scale thickness. A coordinate measuring machine was used to determine the scale thickness on individual wall segments. The growth pattern of the scale was found to be nonuniform due to the variation of fluid velocity near the wall at various heights. Computational fluid dynamics (CFD) simulation showed that fluid flow is time‐dependent and has two distinct flow zones, one involving recirculation through the impeller in the lower part of the vessel and the other involving lower velocities due to the flow separation at the wall in the upper part. CFD simulation also showed the presence of macroinstabilities, which manifest as asymmetrical and chaotic flow structures with relatively long‐time scales. Scale growth is found to be prominent in regions where the fluid velocity and wall shear stresses are low. © 2018 American Institute of Chemical Engineers AIChE J , 64: 3912–3922, 2018