[Samal*et al., 5(8): August, 2016] ISSN: 2277-9655 IC™ Value: 3.00 Impact Factor: 4.116 http: // www.ijesrt.com© International Journal of Engineering Sciences & Research Technology [586] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY HYDRODYNAMICS OF TWO-STAGE LIQUID-SOLID SEMI-FLUIDIZATION D.K. Samal * , Y.K. Mohanty, G.K. ROY, M. Kumar, M. Sekhar, R. Gandhi Department of Chemical Engineering, Gandhi Institute of Engineering and Technology (GIET), Gunupur, Rayagada, Odisha-765022, India DOI: 10.5281/zenodo.60102 ABSTRACT To develop the concept of two-stage semi-fluidization on hydrodynamic characteristics viz. the bed pressure drop and formation of the top packed beds, investigation have been carried out in a two-stage semi-fluidized bed with regular and irregular particles. Perspex column of internal diameter 2.54 cm with a 30 test section cm has been used for two stage study with water as the fluidizing medium. Glass beads and dolomite particles (0.1504 cm) have been used as solid phase material. Experimental parameter studied includes superficial liquid flow rate with constant bed expansion ratio. Mathematical modeling has been done for the bed pressure drop and the top packed bed height for two-stage semi-fluidization. Individual stage behavior and comparison of results have been made between single and the two-stage semi-fluidized bed with fixed amount of total solids and total volume of test section. KEYWORDS: Two-stage Liquid–solid semi-fluidization, Bed pressure drop, Top packed bed formation, Regular and Irregular particles INTRODUCTION A unique technique of fluid solid contact is semi-fluidization, which combines fluidization and packed bed operation in a single vessel. This process has gained many attentions of the researchers starting from 1959 (L T Fan) [1] due to certain advantages over fluidized and packed bed operations. Semi-fluidization technique has immense applications in various fields of chemical and bio-chemical engineering processes [2-7]. By restrict the free expansion of a fluidized bed beyond minimum fluidization condition with the help of a top restraint in the column, semi-fluidized bed forms. This result in the simultaneous formation of a packed bed below the top restraint and a fluidized bed below the top packed bed formed. Minimum and maximum semi-fluidization fluid flow rates (or velocities) are the two extreme values of fluid movement for the course of semi-fluidization phenomena [8]. Single stage semi- fluidized bed functions within two restraints of a vessel (cylindrical or rectangular c/s section). The fluid passes through the bottom restraint and after proper contact with the movable and the stationary solids leaves the system through a top restraint. It is a single stage operation where the fluid properties, solid characteristics and vessel dimensions influence the performance of the semi-fluidizer. The aim of the present work is to develop a two-stage liquid-solid semi-fluidization concept and mathematical models for the bed pressure drop and the top packed bed height formation using spherical particles. Investigation is being carried out in a 2.54 cm internal diameter Perspex column. The effect of the system parameters studied includes superficial liquid flow rate with constant bed expansion ratio and initial static bed height. The experimental data of two-stage semi-fluidization has been compared with that of a single stage operation. SINGLE AND TWO-STAGE SEMI-FLUIDIZATION In single stage semi-fluidization, solid material of certain height (Hs) is kept inside the vessel of effective height R×Hs (where R is bed expansion ratio [9]). The liquid flows through the vessel. The total effective height of the vessel is occupied by a part of the solids in stationary state at the top and the rest of the solids below the top stationary solids in fluidized form. Two single stages are connected in series for the two-stage semi-fluidization operation. In the present investigation, two-stage semi-fluidization test sections are created by splitting single stage semi-fluidization test section with different bottom and top volume ratio.