Experimental investigation of fountain height in a shallow rectangular spouted bed using digital image analysis

A coupled computational fluid dynamics (CFD)discrete element method (DEM) technique has been adopted to examine the dynamic behavior of particles in a rectangular spouted bed. Eulerian method has been used to solve the Navier−Stokes equation for the gas phase (for the CFD) and Lagrangian method (for the DEM) for the particle phase, where the k−ϵ two-equation turbulence model has been used to capture the effect of gas-phase turbulence. In the present work, we sought to predict the minimum spouting velocity (U ms ) numerically for a fixed bed height and particular particle properties. The effects of the inelastic collision and the friction on translational and rotational dynamics of the particles in spout, annulus, and fountain zones have been brought out with the intensive parametric study. The results reported here would be a way forward for a better understanding of the spouted bed processing where translational and rotational dynamics of particles play a key role.

Section: Introductionmentioning

confidence: 99%

Numerical Studies on Particle Dynamics in a Spouted Bed

Raman

Mollick

Goswami

2021

“…Spout beds have been intensively applied in many particulate processes such as coating, gasification, combustion, pyrolysis, and drying due to their excellent mixing efficiency and heat and mass transfers attributed to the intrinsic merit of excellent gas–solid interactions. In spouted beds, a strong gas flow enters the column from the central bottom area, thus forming a spout channel where particles move upward in a dilute phase.…”

Section: Introductionmentioning

confidence: 99%

“…By some advanced image treatment methods, the images could also provide the voidage distribution information . Yang et al , also applied the image analysis method to identify the asymmetrical spouting and “curved gas path” by frame. The pressure drop containing the information of gas–solid flow is also an important indicator for the hydrodynamics in the spouted bed.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Spout Deflection in a Rectangular Spouted Bed by the PIV Method

Yue

Wang

Bahl

et al. 2020

Spout deflection is a common instability phenomenon, which has been widely encountered in spouted and spout-fluidized beds. However, the spout deflection has not been quantified experimentally. In the present work, the alternating spout deflection behavior is captured by employing the particle image velocimetry (PIV) method and quantified based on PIV vector fields over a wide range of variables in terms of bed heights and spouting velocities. The results show that the static bed height has an obvious effect on the alternating spout deflection. The amplitude of the alternating spout deflection keeps stable at first and then reduces quickly with increasing static bed height. The drop tendency is ascribed to the appearance of spout incoherence behavior in which the particle blockage periodically forms and explodes in the spout region. This explosion contributes to uniform particle spurting and reduces the height difference between two annulus regions and the spout deflection amplitude. The amplitude of the alternating spout deflection is stable with increasing spouting velocity, which can be owed to the self-locking phenomenon. Specifically, the particles in the annulus region on one side cannot be transported away due to the resistance of the deflected spout and thereby preventing the further deflection of the spout. Spouting velocity has a neglectable influence on the regularity and main frequency of the alternating spout deflection. This work unveils the hydrodynamics of spout deflection and provides a methodology for experimental investigation of spout deflection in spouted beds.

“…As a nonintrusive method, optical techniques have gained popularity because of the continued rapid advancement of cameras, increased computational processing power, and the development of advanced image processing techniques. Applying digital image processing methods to high-speed videos for hydrodynamic characterization has been conducted in a variety of gas–solid systems including circulating fluidized beds, , fluidized beds, , packed beds, , and spouted beds. , In this work, the hydrodynamic characterization of a rectangular spouted bed is based on systematic image processing methods proposed in our recent studies. − The current study aims to develop correlations requiring less secondary parameters (parameters that rely on experimental data) to predict key hydrodynamic parameters that are significant in the successful design of spouted beds. The hydrodynamic parameters, accorded a good measure of attention, are the peak pressure drop (Δ P max ) and external spouting velocity ( U es ) of both Geldart D and B particles, the accurate knowledge of which can provide practical information for operating power and air compressor requirements and efficient evaluation in spouted-bed reactor design.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Characterization of a Shallow Rectangular Spouted Bed Using Bed Pressure Signals and Image Processing Methods

Yang¹,

Breault

Weber

2020

Self Cite

To support the design of spouted bed reactors, experiments are performed in a rectangular spouted bed to measure the peak pressure drop (ΔP max ) and the internal and external spouting velocities (U is and U es ). Four particle types spanning under Geldart D and B are used. U is and U es are measured from bed pressure drop and expansion ratio profiles, respectively, with the U es /U is ratio of each particle type obtained. Correlations predicting the ΔP max of Geldart D and B particles are developed by reviewing published correlations and investigating the nozzle effect. Good prediction is achieved with a slope of 0.997 and an adjusted R 2 of 0.998 in a 95% confidence interval. U es is predicted through correlations developed by adding effects of d p /D i and H 0 in the Mathur−Gishler equation. The calculated U es agrees well with the experimental data, achieving a slope of 0.998 and an adjusted R 2 of 0.998 in a 95% confidence interval.