Flow Mapping and Modeling of Liquid-Solid Risers

The trend toward environmentally benign processing has resulted in novel chemistries and new reactor types. For alkylation of both aromatics and linear paraffins, with new solid acid catalysts, liquid−solid risers are one of the reactor types considered. As the fluid dynamics of liquid−solid risers is largely unknown, it has been investigated in this work in a 6-in.- (15-cm-) diameter “cold-flow” circulating fluidized-bed riser using noninvasive methods. The time-averaged solids holdup distribution is determined by γ-ray computed tomography (CT). The solids instantaneous and ensemble-averaged velocity patterns, as well as the solids residence time distribution in the riser, is obtained by computer-automated particle tracking (CARPT). Various measures of solids backmixing are evaluated including the eddy diffusivities and the overall axial dispersion coefficient. The obtained database is used for validation of a two-fluid Euler−Lagrange model, which is coupled with appropriate closures including the kineti...

[1]  Milorad P. Dudukovic,et al.  Multiphase reactors – revisited , 1999 .

[2]  Sanjoy Banerjee,et al.  Numerical investigation of the effects of large particles on wall-turbulence , 1997 .

[3]  M. Duduković,et al.  A method for estimating the solids circulation rate in a closed-loop circulating fluidized bed , 2001 .

[4]  J. Chaouki,et al.  3‐D mapping of solids flow fields in multiphase reactors with RPT , 1995 .

[5]  J. Jenkins,et al.  A theory for the rapid flow of identical, smooth, nearly elastic, spherical particles , 1983, Journal of Fluid Mechanics.

[6]  van Wpm Wim Swaaij,et al.  Computational fluid dynamics applied to gas-liquid contactors. , 1997 .

[7]  P. R. Pujadó,et al.  Production of detergent olefins and linear alkylbenzenes , 1990 .

[8]  E. B. Nauman,et al.  Mixing in continuous flow systems , 1983 .

[9]  C. L. Thomas,et al.  Catalytic processes and proven catalysts , 1970 .

[10]  Sanjoy Banerjee,et al.  NUMERICAL SIMULATION OF PARTICLE INTERACTIONS WITH WALL TURBULENCE , 1996 .

[11]  Jan J. Lerou,et al.  Chemical reaction engineering : A multiscale approach to a multiobjective task , 1996 .

[12]  Howard H. Hu,et al.  Direct simulation of fluid particle motions , 1992 .

[13]  B. Launder,et al.  The numerical computation of turbulent flows , 1990 .

[14]  A. A. Amsden,et al.  Numerical calculation of multiphase fluid flow , 1975 .

[15]  D. Gidaspow,et al.  A bubbling fluidization model using kinetic theory of granular flow , 1990 .

[16]  D. Jeffrey,et al.  Kinetic theories for granular flow: inelastic particles in Couette flow and slightly inelastic particles in a general flowfield , 1984, Journal of Fluid Mechanics.

[17]  David J. Jeffrey,et al.  The stress tensor in a granular flow at high shear rates , 1981, Journal of Fluid Mechanics.

[18]  R. Jackson,et al.  Gas‐particle flow in a vertical pipe with particle‐particle interactions , 1989 .

[19]  Said Elghobashi,et al.  A two‐equation turbulence model for two‐phase flows , 1983 .

[20]  Rajamani Krishna,et al.  Strategies for multiphase reactor selection , 1994 .

[21]  Geoffrey Ingram Taylor,et al.  Diffusion by Continuous Movements , 1922 .

[22]  Shantanu Roy,et al.  A two-phase compartments model for the selective oxidation of n-butane in a circulating fluidized bed reactor , 2000 .

[23]  Jacques Villermaux,et al.  Future challenges for basic research in chemical engineering , 1993 .

[24]  R. Bagnold.  Experiments on a gravity-free dispersion of large solid spheres in a Newtonian fluid under shear , 1954, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[25]  Sailesh Kumar,et al.  A γ-ray tomographic scanner for imaging voidage distribution in two-phase flow systems , 1995 .

[26]  D. Drew.  Mathematical Modeling of Two-Phase Flow , 1983 .