Hydrodynamic and Mixing Characteristics of Gas–Solid Flow in a Pulsed Spouted Bed

Abstract

The flow behavior and particle motion in a pulsed gas-solid spouted bed was investigated using the Eulerian-Lagrangian approach. The Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) was used to evaluate the gas flow field and particle trajectories. The model was four-way coupled to account for fluid-particle, particle-fluid and particle-particle interactions. A column of 150 mm × 15 mm cross-section and height 750 mm containing 24,500 particles of diameter 2.5 mm was investigated. Gas entered through a 10 mm × 15 mm slot at the base of the bed. Steady spouting was compared with pulsed spouting at frequencies of 1, 4, and 10 Hz, with superficial velocity amplitude of 0.5 and 1 m/s, and a mean superficial spouting velocity of 2 m/s. In addition to comparing the bed pressure drop versus time and its Fourier decomposition, the hydrodynamics in the spout and annulus regions were examined. A new procedure was introduced to assess spouted bed mixing and homogeneity. Flow pulsation was shown to provide stronger upward air momentum, less horizontal gas percolation, better circulation, higher downward particle flux near the sidewalls, better mixing and greater homogeneity.

Kinetic Modeling and Experimental Investigation of Hydro‐Catalytic Upgrading of Anisole as a Model Compound of Bio‐Oils Derived from Fast Pyrolysis of Lignin over Co/γ‐Al2O3

“…Cellulose is a linear polymer of glucose while the hemicellulose fraction of lignocellulosic biomassis generally comprised of different main monosaccharides containing mannose, xylose, galactose, glucose, arabinose, and other residues like galacturonic, 4-o-methyl glucuronic acid. [4][5][6][7][8] Lignin is of the polyaromatic structure possessing linked aromatic units similar to petroleum and it also acts as a resin which fills up the spaces between cellulose and hemicellulose. Unsaturated oxygenates components in lignin-derived bio-oils formed in pyrolysis process cause several undesirable properties including non-volatility, high viscosity, corrosiveness, poor heating value, immiscibility with fossil fuels, thermal instability, and tendency to be polymerized during storage and transportation.…”

Estimation of Bed Expansion and Separation Density of Gas–Solid Separation Fluidized Beds Using a Micron-Sized-Particle-Dense Medium

“…With the development of coal processing technology, coal with a smaller particle size is produced, and more efficient methods are needed to effectively separate coal of less than 6 mm. The general practice is to introduce external forces into the traditional gas-solid fluidized bed, such as in vibrated fluidized bed [23][24][25], magnetically stabilized fluidized bed [26], and pulsating fluidized bed [27,28]. Although these methods play improve the separation effect, they involve increased energy consumption.…”

An application of factor analysis in wet particle systems: Rolling friction and cohesive liquid controlling performances

“…Liu et al 21 investigated and demonstrated the role of bubbles on solid mixing, and mixing mechanisms were explored in a bubbling fluidized. Luo et al 22,23 and Saidi et al 24 investigated the effect of a draft tube and pulsed gas delivery on the solid mixing characteristics of spouted bed, respectively. However, most prior numerical simulations assumed that particles were spherical.…”