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This article describes the characteristics of ring-shaped electrostatic pulverized fuel meters and their applications. At the University of Teesside, UK, the electrostatic technique has been used to measure pulverized fuel flow concentration, velocity, and mass flow rate under lean-phase condition. The mathematic model has been developed to express the relationship between the root-mean-square (rms) value of the meter's output voltage and solids mass flow rate. The effects of solids velocity and particle size on measurements have also been reflected in the model. Furthermore, the model presents the sensitivity variations over the cross-sectional area of meter and along the pipe axis. The article also introduces the research carried out at Southeast University in China, where the technique has been extended to measure dense-phase flow of pulverized coal, which is common in gasification and blast furnaces. [ABSTRACT FROM AUTHOR]

This article describes the usefulness of embedded cluster and periodic models to solve a number of problems in computational materials science. To this end, two different well-defined problems are selected and discussed. The first problem concerns magnetic coupling in high Tc superconductor parent compounds. It is taken to exemplify the application of quantum chemical methods to derive excited-state properties of extended systems. The second problem concerns the selectivity of a partial oxidation reaction catalyzed by a metal surface. This second example serves to illustrate the efficacy of solid-state band theory methods in the study of chemical reactions taking place at surfaces. Possible extensions of ab initio computational materials science are further discussed. [ABSTRACT FROM AUTHOR]

Solids circulation rate and solids holdup are experimentally investigated in a liquid-solid circulating fluidized bed that covers a wide range in solid and liquid flow rates, particle size, and density. The drift-flux model, which is extensively used to describe the flow behavior of gas-liquid systems, is modified in the present work and for the first time applied to the experimental data of a liquid-solid circulating fluidized bed. The distribution parameter Co is evaluated using the drift-flux model from the present experimental data and also from the data available in the literature. It is found from the analysis that the value of the distribution parameter lies in the range of 0.78 to 0.99, which is a reverse trend to the liquid-gas system. The weighted average drift velocity (usj) is well correlated to the terminal velocity of the particle. The solid holdup predicted using this model agrees with the experimental results. [ABSTRACT FROM AUTHOR]

Performance ratios and pumping power ratios are evaluated in a circular conduit in the presence of a ring promoter in the absence and the presence of fluidizing solids. Qualitative effects of cross-sectional diameter of the ring, spacing between the rings, and diameter of the particle on performance ratio, pumping power ratio, and efficiency index are reported. [ABSTRACT FROM AUTHOR]

Despite much research on gas-liquid-solid systems and their widespread application in industry, gas dispersion with solid suspension in multistage stirred reactors equipped with multiple impellers has received little attention. We report here the critical just-suspension impeller speed for different concentrations of solid particles, gas holdup, and shaft power in a vessel of 0.48 m diameter with four baffles and dished base. Five agitator configurations, each with three impellers mounted on a single shaft, have been used in the experiments. Two novel impeller designs were used, a deep hollow blade (semi-ellipse) disc turbine (HEDT) and four-wide-blade hydrofoil impellers. The hydrofoils were used in both up-pumping (WH U ) and down-pumping (WH D ) modes. Glass beads of 50 ~ 150 µm diameter and density 2500 kg · m -3 were suspended at solid volumetric concentrations of 1.5, 3, 6, 9, and 15%. Results show that these suspended solids have little effect on the relative power demand. Agitators using the HEDT radial dispersing impeller at the bottom have a higher relative power demand (RPD = P G /P U ) than those with WH D or WH U as the lowest one. For all impeller combinations there is little or no effect on gas holdup with increasing solid concentrations. Of the five different impeller combinations, those with an axial flow bottom impeller have significantly higher just-suspension agitation speeds and power consumption, so mounting the hydrofoil impeller at the bottom is not the optimal configuration for particle suspension. Of these impeller combinations, at a given gas flow rate the arrangement of HEDT + 2WH U has the highest relative power demand, gas holdup, and power input for both the suspension of settling particles and gas dispersion. [ABSTRACT FROM AUTHOR]