Abstract
Mixing process under batch operation was investigated by the impulse response method. A series solution of the dispersion model for recirculation flow is given and a simple procedure to determine the model parameter, Bodenstein number Bo, is proposed. Dimensions of the loop reactor used in most experiments are: inner diameter = 10 cm, whole pipe length-=280 cm and reactor volume=22l. The impellers used are: pitched paddles of three different pitched angles and three different diameters, an axial flow pump-type impeller and a marine screw.
Bodenstein number was converted into Peclet number, Pe, which in turn is correlated with the pipe Reynolds number, Rep. For the experimental range of Rep=2.5×103-2×105, Pe ranges over 3-16, which is 2-3 times that in a straight pipe. Geometry of the impeller does not affect the value of Pe for a given value of Rep. Pe in unbaffled condition is larger than that in baffled condition because of helical motion of fluid. The number of circulations before the fluctuation decays below 1 % of average concentration is analytically found to be 0.134 Bo.
