Abstract
The effect of superficial gas and liquid velocities, particle diameter and sphericity, physical and rheological properties of liquids on gas holdup were studied in a three phase internal loop airlift fluidized bed reactor. Air was used as a gas phase. Water, n-butanol, various concentrations of glycerol (60% and 80%) were used as Newtonian liquids and different concentrations (0.25%, 0.6% and 1.0%) of carboxy methyl cellulose (CMC) solutions were used as non-Newtonian liquids. Spheres, Bearl saddle and Rasich ring with different diameters were used as solid phases. Superficial gas velocity varied from 0.000142 m/s to 0.005662 m/s and superficial liquid velocity varied from 0.001 to 0.12 m/s. The experimental result shows that increase in particle size and superficial gas velocity increases gas holdup and decreases with increase in concentration of Newtonian and non-Newtonian systems. Based on the experimental results a separate correlation was developed to predict gas holdup for both Newtonian and non-Newtonian liquids for wide range of operating conditions.
Highlights
The schematic diagram of the experimental setup is shown in Fig. 1.The reactor was constructed of 0.15 m id Perspex column and 1.63 m in height
The liquids used in this study were tap water, n-butanol and 60% and 80% concentrations of glycerol were used as Newtonian fluids and various concentrations of (0.25 %, 0.6 % and 1.0 %) carboxy methyl cellulose (CMC) was used as non-Newtonian fluids
Increase in superficial gas velocity increases the fraction of gas bubbles in the column resulting increase in gas holdup
Summary
The schematic diagram of the experimental setup is shown in Fig. 1.The reactor was constructed of 0.15 m id Perspex column and 1.63 m in height. Inside diameter of the draft tube was 0.084 and 1.54 m in height. The draft tube was located above 0.09 m from the gas distributor. Air was sparged into the draft tube through sparger which is 0.08 m in diameter with holes of 0.0008 m each located slightly below the perforated plate. Superficial gas velocities are varied from 0.000142– 0.005662 m/ s. Superficial liquid velocities are varied from 0.001 to 0.12 m/s. The liquids used in this study were tap water, n-butanol and 60% and 80% concentrations of glycerol were used as Newtonian fluids and various concentrations of (0.25 %, 0.6 % and 1.0 %) CMC was used as non-Newtonian fluids. Different diameters of Spheres, Bearl saddle and Raschig ring were used as solid phases. The properties of liquids and solid particles used in the present study are given in Tables 1 and 2
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