In this study, wet particle flow behaviors were investigated in a spouted bed using numerical simulations and experiments. Effects of liquid contents and viscosities were investigated. For the experiment, instantaneous particle distribution and particle velocity distributions were explored. Liquid content and viscosity affected flow pattern together. Keeping increasing liquid content and viscosity, the flow pattern displayed flow instabilities, and the gas channel became curved. Numerical simulation results of time-averaged particle velocities agreed well with the experimental data. The regime map of domination forces is shown. Drag force has little effect on particle flow behaviors with liquid viscosity exceeding 10 mPa·s, and contact and liquid bridge forces were almost 50–50. Furthermore, effects of liquid content and viscosity on particle granular temperature and velocity were explored. The experimental and numerical simulation results might provide theoretical guidance for reactor design and further investigation on particle flow behaviors with cohesive liquid.

Fluidization of non-spherical particles is very common in petroleum engineering. Understanding the complex phenomenon of non-spherical particle flow is of great significance. In this paper, coupled with two-fluid model, the drag coefficient correlation based on artificial neural network was applied in the simulations of a bubbling fluidized bed filled with non-spherical particles. The simulation results were compared with the experimental data from the literature. Good agreement between the experimental data and the simulation results reveals that the modified drag model can accurately capture the interaction between the gas phase and solid phase. Then, several cases of different particles, including tetrahedron, cube, and sphere, together with the nylon beads used in the model validation, were employed in the simulations to study the effect of particle shape on the flow behaviors in the bubbling fluidized bed. Particle shape affects the hydrodynamics of non-spherical particles mainly on microscale. This work can be a basis and reference for the utilization of artificial neural network in the investigation of drag coefficient correlation in the dense gas-solid two-phase flow. Moreover, the proposed drag coefficient correlation provides one more option when investigating the hydrodynamics of non-spherical particles in the gas-solid fluidized bed.

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Fluidized beds are widely used in many industrial fields such as petroleum, chemical and energy. In actual industrial processes, spherical inert particles are typically added to the fluidized bed to promote fluidization of non-spherical particles. Understanding mixing behaviors of binary mixtures in a fluidized bed has specific significance for the design and optimization of related industrial processes. In this study, the computational fluid dynamic-discrete element method with the consideration of rolling friction was applied to evaluate the mixing behaviors of binary mixtures comprising spherocylindrical particles and spherical particles in a fluidized bed. The simulation results indicate that the differences between rotational particle velocities were higher than those of translational particle velocities for spherical and non-spherical particles when well mixed. Moreover, as the volume fraction of the spherocylindrical particles increases, translational and rotational granular temperatures gradually increase. In addition, the addition of the spherical particles makes the spherocylindrical particles preferably distributed in a vertical orientation. Keywords Non-spherical particle • Fluidized bed • Discrete element method • Binary mixtures Abbreviations CFD Computational fluid dynamic DEM Discrete element method LSD Linear spring dashpot List of symbols C D Drag coefficient d p Particle diameter, m F c Contact force, N F d Drag force, N g Gravitational acceleration, m/s 2 I p Moment of inertia, kg m 2 k Spring stiffness, N/m m p Particle mass, kg M Lacey Lacey mixing index N Number Re Reynolds number r p Position of particle center, m S p Momentum exchange source term, kg/(m 2 s 2) t Time, s T c Torque generated by contact force, N m T r Torque generated by rolling friction, N m u g Gas velocity, m/s Vol Volume fraction of spherocylindrical particles V p Particle volume, m 3 v p Particle translational velocity, m/s Subscript c Contact g Gas phase L Local coordinate system n Normal direction p Particle phase rot Rotation t Tangential direction tran Translation Greek letters β Interphase momentum exchange coefficient, kg/ (m 3 s) δ Elastic deformation, m

Discrete hard sphere particle models and improved large eddy simulations are utilized to investigate the relationship between gas channels and particle behaviour, and the spatial characteristics of particles are explored through region-dependent analysis. A spout-fluidized bed can be divided into upper and lower parts according to clear differences in particle behaviour. Particle motion in the lower section is driven by the gas channel generation process, which leads to a strong gas-solid interaction. In the upper section, strong gassolid interactions occur only in the vicinity of the gas-channel. We find that the complex generation, evolution, and dissolution of the gas channel is anisotropic, which leads to spatial variations in particle behaviour. The influence of various models and operation parameters are investigated, and our results can be used to optimize the design of reactors and enhance gas-solid interactions. K E Y W O R D S DPM, gas channel, LES, spout-fluidized bed

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Fluidized beds are widely used in many chemical engineering industrials, and flow behaviors of multiphase flow have always been the focus of research. This paper presented how rolling friction and cohesive liquid affected wet particle flow behaviors by experiments, simulation, and data analyses. Experiments were conducted for applying a suitable range of rolling friction coefficient. A discrete element method, well validated by comparing experimental data, was developed and demonstrated that μ r = 0.125 was a good choice for particles applied in this work. Data from numerical results were well analyzed by factor analysis, where explained interaction effect of two factors on fluidized beds. Factor analyses reflected that dominating factor and interaction effect on flow behaviors vary instead of single control factor in different regions. These findings have clearly showed importance and effect of microscopic parameter collision characteristics on the hydrodynamic behaviors in fluidized beds. Thus, rolling friction constitutes should be carefully considered to ensure that theoretical results are accurate.