Solid – liquid mass transfer in a fixed – bed reactor operating in induced pulsing flow regime
Advancing the chemical engineering fundamentals
Multifase Flows (T2-5P)
Keywords: trickle-bed, induced pulsing flow, liquid-solid mass transfer
The aim of the presented work was to determine the values of mass transfer coefficients between a liquid and a solid surface in a trickle- bed reactor (TBR) operating in a pulsing flow regime induced by means of cyclic changes in the flow rate of the liquid phase (LIPF- liquid induced pulsing flow) between the high and low value (the method so-called BASE – IMPULSE).
The research was carried out in the reactor of 0.057m in diameter and filled with a 1.37m high layer of glass spheres of 3 mm in diameter. The solid-liquid mass transfer rate was determined electrochemically, based upon the measurement of the density of the current of an electrochemical reaction whose rate is controlled by the diffusion of ions to the surface of an electrode (cathode). The electrolyte used in the research contained 0.01mol/dm3 of potassium ferricyanide, 0.05 mol/dm3 of potassium ferrocyanide and as the so-called current carrier – potassium chloride. The role of the cathode was played by the platinum spheres of diameters equal to that of inert packing and positioned at 0.2 m intervals along the axis of the bed.
Water and water solutions of glycerol (30 wt.% and 45 wt.% respectively) were the liquid phase in the research; nitrogen was used as the gas phase.
The research was carried out only for SLOW MODE periodic liquid feeding because for FAST MODE the region in which induced pulsing flow occurs is practically the same as for the self-induced pulsing flow.
The following were also analyzed: the influence of operational parameters of the reactor (liquid velocity in the base and impulse, the duration of the base and impulse, gas velocity) and physicochemical properties of the liquid spraying the bed on the local and average values of the measured coefficients.
The obtained experimental data base made it possible to determine the values of the so- called enhancement coefficient pointing out how much higher values of mass transfer coefficient are obtained in the induced pulsing flow in relation to the values of this coefficient obtained in the GCF regime at the same average velocity of the liquid phase in bed. It allows us to estimate the benefits resulting from the operation of the reactor in the induced pulsing flow.
See the full pdf manuscript of the abstract.
Presented Tuesday 18, 13:30 to 15:00, in session Multifase Flows (T2-5P).
