Design of multiphase reactor experimental investigations of gas liquid down flow jet loop sparged reactor

Abstract

More than 90% of industrial chemicals are produced by catalytic newlineprocesses and most of these processes involve multiphase systems like fixedbed, newlineSparged, and Stirred contactors for carrying out the two-phase and newlinethree-phase reactions. Reactions such as hydroformylation, carbonylation, newlineoxidation, etc. involve reactants originally present in two phases. Loop newlineReactors (LR) are characterized by well-defined flow pattern, better newlinedispersing effects which can be driven in fluid or fluidized systems by newlinepropeller or jet drive and mainly in Gas-Liquid (G-L) systems. In jet loop newlinereactor, the liquid jet performs the functions of distributing and dispersing newlinethe gas as fine bubbles in the liquid and also in circulating the gas-liquid newlinemixture by momentum transfer. To increase the overall gas holdup and newlinevolumetric mass transfer coefficient, a novel down flow jet loop reactor with newlinebaffles and sparged straight throat ejector is designed. Experiments were conducted in a down flow jet loop sparged reactor having the liquid outlet at the bottom section of the reactor, instead of being at the top to determine the hydrodynamic (overall gas holdup), mass transfer newline(overall mass transfer coefficient) parameters for the gas-liquid system. The newlineinfluence of operational (gas and liquid flow rates), geometrical (sparger newlineopenings and diameter, projection depth of ejector) on these hydrodynamic newlineand mass transfer characteristics are studied. Air and tap water are used as newlinethe gas and liquid phases. Application studies of down flow jet loop sparged newlinereactor were also carried out such as neutralization of alkaline solution by newlineCO2gas absorption and decolorization of textile wastewater using ozone. newlineThe reactor used for this investigation consists of a 14.2 cm ID and 60 newlinecm high perspex tube in which the straight throat ejector with sparger and newlinenon-circular baffles are located coaxially at the center. The liquid is newlinewithdrawn continuously from the bottom of the reactor and circulated back newlineto the straight throat ejector using a liquid circulation pump. Air is fed newlinethrough the G.I pipe on top whereas water enters tangentially in a straight newlinethroat ejector fixed coaxially in the reactor. The volume expansion technique newlineis used for the determination of overall gas holdup. The Transient gassing-in newline(gassing-out) method is used for the determination of the overall volumetric newlinemass transfer coefficient. newlineIt is observed that both overall gas holdup and volumetric mass newlinetransfer coefficient increase with increasing gas and liquid flow rates for gasliquid newlinesystem. The apparent liquid circulation velocity increases with newlineincreasing liquid flow rate for the gas-liquid system. The overall volumetric newlinemass transfer coefficient is found to increase with increasing gas flow rate. newlineInitially, at the lower range of liquid flow rates (uniform bubbling flow newlineregion) a maximum mass transfer rate is observed at a liquid flow rate newlinecorresponding to a minimum energy dissipation rate per volume. At a higher newlinerange of liquid flow rates (churn-turbulent flow region), mass transfer newlineincreases with an increase in liquid flow rate newline newline