LOCAL VELOCITY AND SHEAR DEFORMATION RATE AT MODEL MEMBRANES IMMERSED IN A BIOREACTOR AGITATED BY CURVED-BLADE IMPELLER: THE EFFECT OF MEMBRANE POSITION
Published: 29 Jul 2017
Abstract: A stirred bioreactor equipped with two submerged tubular membrane modules and curved-blade, backswept (BS) impellers is studied. The membranes are positioned in different parts of the vessel, a subsurface and a bottom one. The flow conditions at the membranes for effective fouling control are targeted. Contemporary CFD methodology is applied. The zones of major importance for effective operation of the membranes are examined and the values of hydrodynamic parameters are revealed. In these zones, the local velocity and shear parameters’ distributions are determined. The flow parameters are correlated with impeller rotational speed and fluid viscous properties. Angular velocity is varied between 600 and 1100 rpm and bulk viscosity is varied between 1 and 60 mPa s. The role of aeration is specified. The maximum shear rates at the membrane interface are registered. The corresponding stress force imposed by the BS impellers is compared with the one generated by conventional flat- blade Rushton turbine (RT). The hydrodynamic data are compared with reference data from the literature and the possibility for effective operation non-damaging for living micro-organisms is discussed.
Keywords: membrane technology, stirred bioreactors, modeling and simulation
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