P.-F. Fauquex

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.

The Application of Fluidized Beds for Improved Enzyme Reactor Performance

Experiments to reduce fluidized bed channeling, circulation of biocatalyst, and flow instability (1) were done using a 40 mm dia by 2.96 m long column, with and without internal elements to reduce circulation of the golid biocatalyst and backmixing. As internals, two types of SULZERR static mixing elements SMX and SMV were used (2). The biocatalyst was Aspergillus niger lactase on chitosan coated silica gel particles of mean particle dia 0.14 mm and an apparent density of 1.47 g/cm3. The residence time distribution of the liquid phase in the different reactors was determined using the stimulus response technique with pulse input of the tracer (aq. HCl). The concentration time function of the tracer was determined by conductivity at 0.725 m and 2.315 m from the column inlet. The measured input at the first position was convoluted with a residence time distribution function of reactor models for non-ideal flow. By fitting the calculated curve with the measured output signal at the second position, a model discrimination and model parameter were obtained: the number of tanks of the tanks-in-series model.

Expansion behavior of liquid solids fluidized-beds with intrenals

A large no. of liq./solid systems is examd. on a lab. scale to find out the effect of internals (e.g. static mixers) on the expansion behavior of fluidized beds. The expansion behavior is evaluated as a function of Archimedes no. With decreasing Archimedes no., effect of the internals is stronger. The effect is the strongest in quasi-laminar flow and negligible in turbulent flow. [on SciFinder (R)]