Simulations of Liquid Spreading and Particle Aggregation in Gas-Fluidized Beds

Introduction of a binding or reacting liquid into a gas-solid fluidized bed is common in industrial processes (e.g. fluid coking, catalytic cracking, granulation). Ability of the liquid to spread and the attractive effect on particles due to liquid bridge formation alter the fluidization behavior and process efficiency.;Liquid diffusion is slower horizontally than vertically. The relation between liquid spreading and solids volume fraction depends on liquid viscosity and surface tension. Systems simulated generally completely aggregate, with aggregation resulting in slip velocity increases.;Direct numerical simulations are performed using the lattice-Boltzmann method, with liquid modeled as a scalar transferred during particle collisions. A liquid spreading model is introduced based on a liquid bridge growth rate, and liquid spreading is studied and analyzed in terms of diffusion coefficients. Then, a system of homogeneously wetted particles is simulated, with an attractive force applied between adjacent particles. Aggregate sizes and fluidization behavior are examined.