DEM Study of Wet Cohesive Particles in the Presence of Liquid Bridges in a Gas Fluidized Bed

Yurong He,Wengen Peng,Shengnan Yan,Tianyu Wang

doi:10.1155/2014/316568

Yurong He, Wengen Peng + Show 2 more

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https://doi.org/10.1155/2014/316568

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Abstract

A modified discrete element method (DEM) was constructed by compositing an additional liquid-bridge module into the traditional soft-sphere interaction model. Simulations of particles with and without liquid bridges are conducted in a bubbling fluidized bed. The geometry of the simulated bed is the same as the one in Müller’s experiment (Müller et al., 2008). A comparison between the dry and the wet particular systems is carried out on the bubble behavior, the bed fluctuation, and the mixing process. The bubble in the dry system possesses a regular round shape and falling of scattered particles exists while the bubble boundary of the wet particles becomes rough with branches of agglomerates stretching into it. The mixing of the dry system is quicker than that of the wet system. Several interparticle liquid contents are applied in this work to find their influence on the kinetic characteristic of the wet particle flow. With an increase of liquid content, the mixing process costs more time to be completed. Symmetrical profiles of the velocity and granular temperature are found for two low liquid contents (0.001% and 0.01%), while it is antisymmetrical for the highest liquid content (0.1%).

Highlights

Particular systems are very common in petroleum, food, chemical, and energy industries
To investigate the hydrodynamics of the wet cohesive particles in a gas-fluidized bed, a modified discrete element method (DEM)-computational fluid dynamics (CFD) numerical method was developed by compositing an additional liquidbridge module into the traditional soft-sphere interaction model
Different liquid contents are applied in this work to find their influence on the kinetic characteristic of the wet particular system

Summary

Introduction

Particular systems are very common in petroleum, food, chemical, and energy industries. These engineering processes involve highly complex phenomena of gas-solid twophase flow, which include particle mixing and segregation, formation of agglomerate, heat transfer, drying, and liquid transfer between particles in wet systems. The DEM method, originally proposed by Cundall and Strack [1], provides a robust technique for investigating the kinetic characteristic of particle flows. Combination of the DEM and CFD methods has emerged as one of the most important tools in probing granular flows in spouted bed [2, 3], gas-fluidized bed [4,5,6,7], vibrating bed [8, 9], mixer [10, 11], and hopper [12]

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