The CREC Fluidized Riser Simulator. Characterization of Mixing Patterns

Abstract

The CREC Riser Simulator Reactor is a new laboratory scale unit that was invented at CREC-UWO (de Lasa, 1991). It was specially designed for catalyst testing and kinetic modeling under the conditions of riser and downer reactors. Preliminary work on mixing patterns in the Riser Simulator was already effected by our group using a helium tracer and a constant temperature hot wire anemometer (Pekediz et al, 1993) with both of these devices placed in the outer reactor annulus. However and given the possible ambiguity of the mixing patterns established with these data, helium tracer was injected in the present study into the central catalyst basket, while velocity measurements were effected in the outer annulus. This methodology allowed the definition of effective gas mixing time and gas superficial velocities at various reactor pressures and impeller speeds with increased confidence. This study found that gas mixing times corresponding to high gas recirculation rates in a CREC Riser Simulator occur over impeller rotational speeds ranging from 3000-6000 rpm and total reactor pressures ranging from 1-5 atm. With this end, gas mixing patterns in a Riser Simulator represent a well mixed unit, and thus, the importance of the Riser Simulator can be realized in the context of its potential use for gas-solid reaction kinetics.