ChemrcalE~~neenngSc2ence Vol 35,pp 82-89 Pergamon Press Ltd ,1980, Pnntedm Great Bntaln 11 OPERATING ZONE AND SCALE UP OF MECHANICALLY STIRRED GAS-LIQUID REACTORS R. BOTTON (*), D. COSSERAT (*) and J.C. CHARPENTIER (w) (*) Rhone Poulenc Industries, Centre de Recherches de Decines, 69150 DECINES, France (us) Laboratoire des Sciences du Genie Chrmique, CNRS-ENSIC, 54042 NANCY, France ABSTRACT The aim of the present study was first to propose non drmensional correlations allowing for calculation and scale up of the gas holdup, lrqurd-side mass transfer coefficient and mechanical power In gas liquid stirred tankswhen such parameters as superficral gas velocrty and stirrIng speed are grven Then a comparison of the performances of these equrpment with those of bubble column reactors was undertaken KEYWORDS Gas holdup, lrquid-side mass transfer coefficrent, mechanrcal power, scale-up, stlrred gas-lrqurd reactors INTRODUCTION Hydrodynamrcs and mass transfer rn mechanically stirred reactors have been intensively studied (see Refs ). However stable and optimally operating zone and scale up of these reactors are not yet perfectly defined The present paper reports experimental hydrodynamrcs and mass transfer data rn tanks of increasrng srzes. This was done In the scope of applied researches for improvement of the Rhone Poulenc process for manufacture of adipic acrd by air oxydation of cyclo- hexane. EQUIPMENT AND PROCEDURE Four vertical cylrndrical baffled tanks of 0.085 , 0.12 , 0.25 and 0.60 m diameter T, constructed of transparent PVC with flat bottom were used These reactors will be re- ferred to as R8 5, Rl2. R25 and R69 Six turbines of the Rushton type wzth srx flate blades wrll be referred to as Al to Ag. They differ one from another by the diameter D and height h of the blades Details of the experimental procedure are presented in Ta- ble 1. The Al agitator corresponds to the standard Rushton turbine geometry. Experrmental data wrth A2 wrll show the influence of the height of the blades, wrth A3 the strrrer drame- ter and wrth A6 the cumulative effect of these two parameters The A4 and A5 agitators give complementary Informatrons on the influence of the height of the blade In all ex- periments the turbine blade length is a = 0.25 D, the disc diameter d = 0.75 D and all the turbines are located at s = T/3 above the bottom of the vessel The six baffles of width C = T/10 are close to the wall of the tanks and therr herght is greater than the height H of the emulsron The height H was kept constant by a liqurd overflow srtuated at a distance T = H above the vessel bottom The gas spargers are perforated annular torus with a diameter 0.22 T located at a distance T/6 above the reactor bottom wzth 1 2 and 2.5 mm diameter holes dependrng on the drameter of the vessel ho;es was chorced to obtain the same sparge velocrty V The number of o for a given superfrcral gas velocity UG in the different reactors. 82