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The IUP Journal of Chemical Engineering
Studies on Pressure Drop and Bed Porosity in Liquid Fluidized Beds with Twisted Tape Internals
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Pressure drop and bed porosity data have been obtained in a liquid fluidized bed in the presence of a twisted tape internal. Glass spheres of diameters 3.13, 4.57 and 6.29 mm were employed as bed material. Tape width varied from 2 to 4 cm and the tape pitch from 11 cm to . The modified friction factor increased with increasing particle diameter. Increase in tape pitch caused a decrease in modified friction factor. The bed porosity decreased with increase in particle diameter. The influence of tape pitch and tape width on bed porosity was observed to be insignificant.

 
 

Fluidization found many applications in process industry (Kunii and Levenspiel, 1991). Applications of fluidization are found in coal gasification, obtaining gasoline from petroleum and natural gas, carrying out catalytic reactions, coating of metal particles, drying of solids, adsorption, fluid catalytic cracking, thermal cracking, coal combustion, incineration of solid waste, activation of carbon, calcination, roasting of sulfide ores, in making ultra pure silicon for semiconductor and solar cell uses, halogenation of metal oxides, reduction of iron ores, cultivation of microorganisms, etc.

On many occasions, internal elements such as baffles, immersed heaters, geometrical irregularities, etc., are used in these applications. Some times the presence of turbulent promoters may be obvious to achieve augmented heat and mass transfer rates. Therefore, the usage of internal elements becomes inevitable, however, with increased complexity in understanding the flow patterns and transport phenomena. The augmentation techniques are broadly categorized as active and passive methods. In active methods energy from an external source is required. Augmentation is obtained by suitably modifying the flow passage leading to increased turbulence and is employed in passive methods. Among all the passive methods, employing displaced devices like twisted tapes are quite common.

Investigations on augmentation of mass transfer rates in homogeneous flow and fluidized beds employing cross-flow elements (Bhaskara Sarma et al., 1986a and 1986b), coiled wires (Rajendra Prasad et al., 2004), string of spheres (Sitaraman, 1977), string of cones (Sarveswara Rao and Raju, 1986), string of discs (Ravi et al., 1996a; and Venkateswarlu et al., 2000), helical tape on a rod (Sujatha et al., 1997 and 2003), ring promoter (Venkateswarlu et al., 2003), etc., were reported. The effect of discs (Ravi et al., 1996b; and Murty et al., 2011) and helical tapes (Rama et al., 1997; and Ramesh et al., 2009a and 2009b) on pressure drop and bed porosity of liquid-fluidized beds and gas-liquid-fluidized beds respectively carried out.

 
 

Chemical Engineering Journal, Metal Ions Onto Eggshell Powder, Heavy Metal Contamination, Water Resources, Traditional Treatment Techniques, Aquatic System, Equilibrium Biosorption Data, Biosorption Processes, Biomass Concentration, Biosorption Equilibrium, Biosorption Isotherm, Redlich Peterson Models.