Case Of Solid Particles Research Articles

Modeling of Limestone Dissolution for Flue Gas Desulfurization with Novel Implications

Solid-liquid dissolution is a central step in many industrial applications such as pharmaceutical, process engineering, and pollution control. Accurate mathematical models are proposed to improve reactor design and process operations. Analytical methods are significantly beneficial in the case of iterative methods used within experimental investigations. In the present study, a detailed analytical solution for the general case of solid particles dissolving in multiphase chemical reaction systems is presented. In this model, the authors consider a formulation that considers the particles’ shape factor. The general case presented could be utilized within different problems of multiphase flows. These methods could be extended to different cases within the chemical engineering area. Examples are illustrated here in relation to limestone dissolution taking place within the Wet Flue Gas Desulfurization process, where calcium carbonate is dissolving in an acidic environment. The method is the most common used technology to abate SO2 released by fuel combustion. Limestone dissolution plays a major role in the process. Nevertheless, there is a need for improvements in the optimization of the WFGD process for scale-up purposes. The mathematical model has been tested by comparison with experimental data from several mild acidic dissolution assays of sedimentary and metamorphic limestone. We have found that R2 ⊂ 0.92 ± 0.06 from dozens of experiments. This fact verifies the model qualifications in capturing the main drivers of the system.

Particle Flow Control by Pulsating Gas Injection in Gas-Solid Fluidized Bed.

The effect of pulsating gas injection on the flow pattern was studied numerically. Discrete element method was applied to the solid-phase calculation. To examine the effect of particle condition, two case of solid particles were considered : one is Group B particles in Geldart's classification and the other is Group D particles. The multiple bubbling state without pulsation was chosen as the basis gas-flow condition. In order to characterize quantitatively the effect of the gas pulsation on the flow pattern, we analyzed power spectra of the distributions of void fraction and solid velocity. The results of the present simulations suggests that the gas pulsation largely modifies the solid flow patterns in a low frequency range. Especially in the case of Group B particles, the pattern of bubbles tends to be ordered by applying the gas pulsation.

Crystallization nuclei in liquid in a sound field

This paper is concerned with the theoretical investigation of crystallization nuclei undergoing radially symmetric oscillations in supercooled liquids and supersaturated solutions exposed to a sound field. Periodic crystallization and melting processes occurring in the course of these oscillations are shown to result in higher amplitudes. This enhances the nonlinear interaction of sound with an oscillating nucleus which results in the phenomenon of rectified heat transfer, i.e. a slow (as against the sound cycle) process of heat pumping into a nucleus. Another peculiar feature of the nonlinear interaction between the sound and the nuclei is evidenced by the fact that the location of nucleation sites in a standing sound wave depends on the dimensions of nuclei and the sound frequency—a situation differing substantially from the case of solid particles without phase transformations. It is shown that phase transformations may markedly increase the absorption and dispersion of the speed of sound propagating in crystallizing liquids as compared with liquids containing solid particles without phase transformations. It is also shown that an increase in the amplitude of the oscillations of crystallization nuclei enhances their interaction with each other.