L-S mass transfer in G-L-S countercurrent magnetically stabilized bed with amorphous alloy SRNA-4 catalyst

Liquid-solid （L-S） mass transfer coefficients （Ks） were characterized in a gas-liquid-solid （G-L-S） three-phase countercurrent magnetically stabilized bed （MSB） using amorphous alloy SRNA-4 as the solid phase. Effects of superficial liquid velocity, superficial gas velocity, magnetic field strength, liquid viscosity and surface tension were investigated. Experimental results indicated that the external magnetic field increased Ks in three-phase MSB, as compared to those in conventional G-L-S fluidized beds; that Ks increased with magnetic field strength, superficial gas and liquid velocities and decreased with liquid viscosity and surface tension; and that Ks showed uniform axial and radial distributions except for small increases close to the wall. Dimensionless correlations were established to estimate Ks of the G-L-S countercurrent MSB using SRNA-4 catalyst, with an average error of 3.6%.     

Magnetically stabilized bed dust filters Analysis through variable length scale approach

Magnetically stabilized beds are packed beds subjected to fluid-driven deformation and controlled by magnetically induced interparticle forces. This paper deals with magnetically stabilized beds as deformable porous media and describes their application in dust filtration. The Richardson-Zaki scaling law, U/Ut = ε^n describes the field controlled bed expansion via the exponent n, that yields a porosity-dependent flow length scale dc = dpε^n. The paper addresses two issues： （i） deformation characteristics by assuming homogeneous bed expansion and a definition of bed variable flow length scale; （ii） dust filtration characteristics such as filter coefficient, specific deposit and filtration efficiency expressed in terms of the variable flow length scale and illustrated by experimental data.     

Removal of dust from flue gas in magnetically stabilized fluidized bed

A magnetically stabilized fluidized bed (MSFB, φ 500mm x 2100mm) was designed to study dust removal from flue gas. Based on the mechanism of dust removal in a fixed bed, the effects on collection efficiency of magnetic field intensity, ratio of flue gas velocity to minimum fluidization velocity, bed height, and particle average diameter, were investigated. Then feasible methods for MSFB to better remove dust were proposed. Over 95% of dust removal with MSFB can be achieved, when stable fluidization is maintained and when magnetic particles are frequently renewed.     

Removal of dust from flue gas in magnetically stabilized fluidized bed

A magnetically stabilized fluidized bed （MSFB,Ф 500mm×2100mm） was designed to study dust removal from flue gas. Based on the mechanism of dust removal in a fixed bed, the effects on collection efficiency of magnetic field intensity, ratio of flue gas velocity to minimum fluidization velocity, bed height, and particle average diameter, were investigated. Then feasible methods for MSFB to better remove dust were proposed. Over 95 % of dust removal with MSFB can be achieved, when stable fluidization is maintained and when magnetic particles are frequently renewed.     

3D CFD modeling of acetone hydrogenation in fixed bed reactor with spherical particles

Acetone hydrogenation in a fixed bed reactor packed with spherical catalyst particles was simulated to study the effects of inlet gas velocity and particle diameter on hydrogenation reaction. Computational results show that the catalyst particles in the reactor are almost isothermal, and the high isopropanol concentration appears at the lee of the particles. With the increase of inlet velocity, the outlet isopropanol mole fraction decreases, and the total pressure drop increases drastically. Small diameter catalyst particles are favorable for acetone hydrogenation, but result in large pressure drop.     

Identification of flow regimes and determination of the boundaries for magnetized fluidized bed with Geldart-B particles

The magnetized fluidized bed (MFB) with Geldart-B particles exhibits many distinct flow regimes depending on the magnetic field intensity (H) and gas velocity (U_g). The identification of these regimes was reviewed for the MFB with magnetizable particles and that with binary admixture of magnetizable and nonmagnetizable particles. Meanwhile, methods for determining the boundaries between two adjacent flow regimes were clarified. The MFB state was found to depend not only on H and U_g but also on their application sequence (i.e., operation mode) within certain operating zones. The dependence feature arose from that the MFB therein could have different equilibrium states for the same combination of H and U_g. Furthermore, such a polymorphic characteristic of the MFB was revealed to result from the internal friction among the particles that were in unfluidized/packed state. Many of the MFB states were demonstrated to be in metastable equilibrium. Nevertheless, they differed significantly from the metastates well-known in the discipline of physical chemistry, such as supercooling and superheated. In fact, they belonged to the amorphous/glass state. This review will deepen our hydrodynamic understanding of the MFB and further promote its commercial application in the chemical and biochemical industries.     

Flow characteristics of mixed particles with a simulated cold state in moving bed reactor

The funnel flow of high-temperature circulating ash and coal in moving bed with height restrictions directly influences the efficiency of coal pyrolysis and scale-up design of reactor. It is one of the technical bottlenecks in the use of moving bed. In order to provide data support for the particle flow and pyrolysis model close to the actual working conditions in the future, this study describes the flow characteristics of solid–solid mixed particles in a cold two-dimensional moving bed. The results indicate that flow characteristics of mixed particles in the quartz sand–coal system are better than those in the cold circulating ash–coal system. The optimized conditions were obtained, the insert half angle is 20° and a heat carrier to coal ratio of 6:1. As the mixture progressed downstream, secondary separation of the heat carrier and coal become apparent. Furthermore, mixture residence time has been investigated to explore the relationship between regional residence time and to predict accurately the actual pyrolysis progress in pyrolyzer.