A novel surface aeration configuration featured with a self-rotating and floating baffle (SRFB) and a Rushton disk turbine (DT) with a perforated disk has been developed. The SRFB, consisted of 12 fan blades twisted by an angle of 30° to the horizontal plane, is incorporated onto the impeller shaft to improve gas entrainment, bubble breakup, mixing in a φ154mm agitated vessel. This new configuration is compared to the conventional DT surface aeration experimentally. The results suggest that the critical impeller speed for onset of gas entrainments is lower for the new configuration and it demands greater power consumption. Moreover, the SRFB system produces 30%-68% higher volumetric mass transfer coefficient per unit power input than that obtained in the conventional DT surface aerator under the same operation conditions.
Hydroformylation of 1-dodecene was studied in a biphasic system using water-soluble rhodium complex [RhCl(CO)(TPPTS)2] as catalyst in the presence of cetyl trimethyl ammonium bromide as surfactant to enhance the reaction rate. Efforts were devoted to improve the performance of hydroformylation by exploring reactor the reaction configuration which enhanced the mixing, dispersion and interphase mass transfer. Experiments were carried out in a 0.5L autoclave at the total pressure of 1.1MPa and temperature from 363K to 373K. Several surface aeration configurations were tested, and higher hydroformylation rate with higher normal/branched aldehyde ratio produced were achieved. The experience suggest that improved reactor configuration by taking reaction engineering, measures is beneficial to better process economy in alkene hydroformylation.
For the mass transfer to single drops during the stage of steady buoyancy-driven motion, experimental
measurement is complicated with the terminal effect of additional mass transfer during drop formation and coa
lescence at the drop collector. Analysis reveals that consistent operating conditions and experimental procedure
are of critical significance for minimizing the terminal effect of drop coalescence on the accuracy of mass transfer
measurements. The novel design of a totally-closed extraction column is proposed for this purpose, which guaran
tees that the volumetric rate of drop phase injection is exactly equal to that of withdrawal of drops. Tests in two
extraction systems demonstrate that the experimental repeatability is improved greatly and the terminal effect of mass transfer during drop coalescence is brought well under control.
In accordance to the anisotropic feature of turbulent flow, an anisotropic algebraic stress model is adopted to predict the turbulent flow field and turbulent characteristics generated by a Rushton disc turbine with the improved inner-outer iterative procedure. The predicted turbulent flow is compared with experimental data and the simulation by the standard κ-ε turbulence model. The anisotropic algebraic stress model is found to give better prediction than the standard κ-ε turbulence model. The predicted turbulent flow field is in accordance to experimental data and the trend of the turbulence intensity can be effectively reflected in the simulation. The distribution of turbulent shear rate in the stirred tanks was simulated with the established numerical procedure.
An orthogonal experiment design is adopted for studying the macroscopic reaction kinetics of hydroformylation of 1-dodecene catalyzed by water-soluble rhodium complex. The experimental data of reaction rate and n∶i aldehyde ratio are analysed by margin and variance analyses. The optimal hydroformylation reaction conditions are suggested by compromise of initial reaction rate and normal/isomeric ratio of product aldehyde.
