E. Flaschel

Bulk polymerization of styrene in a static mixer

An experimental investigation of thermal bulk polymerization of styrene in a pilot plant will be reported. The plant is composed of a recycle tubular reactor followed by a tubular reactor. The conversion of the pre-polymerization part is in the range of 0 to 60% and at the outlet of the pilot plant up to 96%. Studies on the residence time distribution show plug-flow behaviour for a variety of different conditions with respect to viscosity and density gradient. The polymers obtained are characterized by gel permeation chromatography and compared to commercial products.

24Na and 99mTc Tracers Applied to the Characterization of Liquid-Solid Fluidized Bed and Hydraulic Transport Reactors

For the characterization of fluidized bed- and hydraulic transport reactors, two radiotracer techniques have been developed permitting the study of mixing phenomena in flowing liquids as well as in beds of fluidized particulate solids. For labelling the aqueous phase, a 99mTc containing solution obtained by means of a 99Mo isotopic generator has been used. The silica gel employed for fluidization has been activated by thermal neutrons to yield a 24Na tracer derived from its natural sodium content.

Determination of partition coefficients of labile compounds subject to dissociation extraction: Analysis of partitioning

A novel method for the determination of partition coefficients in aqueous-organic two-phase systems is described. It is applicable for characterizing the distribution of substances undergoing proton dissociation in the aqueous phase. The method is based on titration by means of the organic phase. A linear form of the respective model is given for parameter estimation by linear regression. This strategy is used for the determination of the partition coefficients of some N-unprotected n-alkyl esters of phenylalanine in various aqueous-organic biphasic systems. These esters are of interest for the optical resolution of phenylalanine with chymotrypsin.

Effect of static mixers on expansion and axial dispersion of liquid in fluidized beds at low reynolds number

Abstract The difference of static mixers as internals on expansion and dispersion characteristics of a liquid fluidized bed was studied experimentally. The column diameter was varied between 39 and 300 mm. Fluidized bed reactors equipped with internals exhibit a high hydrodynamic stability accompanied by an increase in the operating range in terms of flow rate by a factor of 4-5 compared to the classical fluidized bed. The axial dispersion of the liquid depends on the Archimedes number, the hydraulic diameter of the static mixer and expansion. The dispersion increases with decreasing Archimedes number and increasing hydraylic diameter of the bed. Dispersion was in general reduced with bed expansion.