Effect of baffle configuration on hydrodynamics and solid suspension in a continuous stirred vessel

Abstract

Hydrodynamics of stirred vessel is difficult to predict due to complex flow conditions existing inside the reactor. Hence in this present work, hydrodynamics and solid suspension in a continuous stirred vessel are numerically investigated using Computational Fluid Dynamics (CFD). To predict the flow field, transient 3 D CFD simulations are performed using Multiple Reference Frame along with Sliding Mesh approach and realizable k-ε turbulence model. The flow field is quantified by spatial/temporal variation of liquid velocity magnitude and liquid circulation. To improve the performance of the stirred vessel, draft tube baffle configurations are proposed and these predictions are compared with the unbaffled system. Further, the suspension characteristics of solids are predicted using the Euler-Granular model and quantified by calculating cloud height in stirred vessel system. The solid concentration is found to be uniform in the baffled stirred vessel and it is concentrated at the bottom of the vessel in the unbaffled stirred vessel. Thus, the proposed draft tube configuration supports in achieving the uniform distribution of solids and overcomes sedimentation of solids in stirred vessel system.

Keywords:

• CFD
• draft tube baffle
• flow field
• liquid circulation
• solid suspension
• stirred vessel

Acknowledgement

The authors express their gratitude to Mr. Lister H Falleiro and Mr. Sai Teja M V, for their support in drafting the manuscript.