Hydrodynamics Modeling of an LSCFB Reactor Using Multigene Genetic Programming Approach: Effect of Particles Size and Shape

The multigene genetic programming (MGGP) technique based hydrodynamics models were developed to predict the solids holdups of a liquid-solid circulating fluidized bed (LSCFB) riser. Four different particles were considered to investigate the effects of particle size, shape and density on hydrodynamics behavior of the LSCFB riser. In this regard, two spherical shape glass bead particles (500 and 1200μm), two irregular shape lava rock particles (500 and 920μm) were employed as solid phase and water as liquid phase. The MGGP models were developed, relating the solids holdup (ϵs $\varepsilon -s$, output parameter) with eight input parameters. The developed models were first validated by comparing the model predicted and experimental data of solids holdups. The average solids holdups decreased with the increase of net superficial liquid velocity (Ul-Ut $U-l - U-t$) and normalized superficial liquid velocityUlUt $\left( \fracU-lU-t \right)$. Uniform axial solids holdups observed in axial locations (H) except close to the liquid-solid distributor of the riser. The radial non-uniformity of solids holdup observed all radial positions (r/R). In the central region almost flat but increased toward the wall region. The radial profiles of the solid holdup are approximately identical at a fixed average cross-sectional solid holdup for all of the three LSCFB systems of this study. The statistical performance indicators such as the mean absolute percentage error and correlation coefficient are also found to be within acceptable range.