Experimental Study of Multiphase Flow in the Presence of Raceway in the Packed Beds
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The lower part of the iron-making blast furnace is very important for operational stability and productivity of it. It represents a multiphase flow, including a cohesive zone. In order to reduce the coke consumption and hence reduce the environmental problems, pulverized coal is injected laterally through the tuyeres. This multiphase (gas-powder-liquid) flow system has been studied at room temperature in the presence of a raceway using new methods to estimate the static and dynamic powder holdups. Reproducible results have been obtained, which were lacking in the previous studies carried out by other researchers. The effect of powder size, gas flow rate, packing size, and liquid flow on fluid flow behaviour and powder holdup has been studied in detail. The pressure drop profiles were compared and explained for both the rectangular and cylindrical beds. Correlations for the static and dynamic powder holdups have been proposed for the various conditions. One of the aims was to study the combination of cross and counter-current flow in a multiphase system and quantify the liquid and powder holdups in presence of raceway. The study revealed localized flooding in the packed bed, which increased with the gas and liquid flow rates. The quantification of holdups revealed higher liquid accumulation and low powder accumulation with increase in the gas velocities.