Due to the motion of gas-bubbles and the particles back-mixing, the particles flow pattern through the plug flow fluid bed dryer deviates from the ideal plug flow and is considered as a dispersed plug flow. In this study, the residence time distribution (RTD) characteristics, flow pattern, and dispersion coefficient of rough rice in a plug flow fluid bed dryer under various experimental conditions were investigated. The effects of solid feed rate (46, 96, and 135 g/min), weir height (5 and 10 cm), and inlet solid moisture content (10 and 30% d.b) on RTD were studied using the pulse input of tracer (dye-coated rough rice). The flow of particles in the dryer is a dispersed plug flow with large deviation from ideal plug flow. The values of dispersion coefficient range from 2.60×10−4 to 4.50×10−4 m2/s over the investigated conditions. The flow in the dryer approaches plug flow with increase in the solid feed rate, decrease in the weir height, and increase in the inlet solid moisture content.
Keywords: Dispersion, Plug Flow, Residence Time, Rough Rice, Fluid Bed Dryer
Due to the motion of gas-bubbles and the particles back-mixing, the particles flow pattern through the plug flow fluid bed dryer deviates from the ideal plug flow and is considered as a dispersed plug flow. In this study, the residence time distribution (RTD) characteristics, flow pattern, and dispersion coefficient of rough rice in a plug flow fluid bed dryer under various experimental conditions were investigated. The effects of solid feed rate (46, 96, and 135 g/min), weir height (5 and 10 cm), and inlet solid moisture content (10 and 30% d.b) on RTD were studied using the pulse input of tracer (dye-coated rough rice). The flow of particles in the dryer is a dispersed plug flow with large deviation from ideal plug flow. The values of dispersion coefficient range from 2.60×10−4 to 4.50×10−4 m2/s over the investigated conditions. The flow in the dryer approaches plug flow with increase in the solid feed rate, decrease in the weir height, and increase in the inlet solid moisture content.
Keywords: Dispersion, Plug Flow, Residence Time, Rough Rice, Fluid Bed Dryer
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