Artículos de revistas
Calcium alginate beads motion in a foaming three-phase bubble column
Fecha
2017-05Registro en:
Salierno, Gabriel Leonardo; Maestri, Mauricio Leonardo; Piovano, Stella Maris; Cassanello Fernandez, Miryam Celeste; Cardona, Maria Angelica; et al.; Calcium alginate beads motion in a foaming three-phase bubble column; Elsevier Science Sa; Chemical Engineering Journal; 324; 5-2017; 358-369
1385-8947
CONICET Digital
CONICET
Autor
Salierno, Gabriel Leonardo
Maestri, Mauricio Leonardo
Piovano, Stella Maris
Cassanello Fernandez, Miryam Celeste
Cardona, Maria Angelica
Hojman, Daniel Leonardo
Somacal, Héctor Rubén
Resumen
Calcium alginate beads are frequently used to immobilize enzymes or microorganisms for fermentations carried out in agitated or pneumatic reactors. In this work, the well-known Radioactive Particle Tracking (RPT) technique is used to non-invasively extract relevant information of the motion of calcium alginate beads within a three phase bubble column under foaming conditions, which frequently appear in bioreactors operation. Special care is taken to produce a radioactive tracer that perfectly matches the features of the other particles in density and size. In addition, the tracer has the same texture and wettability since the adherence of gas to particles in foaming systems is crucial in determining the solid motion. Particles distribution, solid residence time, velocity fields, dispersion coefficients, shear stress and turbulence kinetic energy are determined from the radioactive tracer trajectories. Compared to previous works in non-foaming systems with denser particles, a relatively strong inward flow and less definite descending motion of the solid near the column wall is found. Turbulence intensities and shear stress are high in the disengagement zone, particularly for the churn-turbulent flow regime. However, since the biocatalyst damage would also depend on the actual exposure to harsh regions, the frequency of visit at different location was calculated to estimate maps of exposure risks as the product of turbulence stresses and these frequencies. Considering the particles motion, the region of largest risk for hydrodynamic damage is close to the gas entrance zone.