Macro-mixing, partial segregation and 3-D selectivity fields inside a semi-batch stirred reactor

The fluid phase reaction A + B --> R to a desired product, when accompanied by a parallel decomposition to a by-product A --> S, form a pair of reacti ons ideal for evaluating mixing-with-reaction tests. The reactions are typi cal of diazotisation in dyestuff manufacture, so that fundamental mixing st udies can be linked to practical manufacturing. Earlier studies on these pr oblems used a 2-D analysis which is approximate for some practical cases. T his approach has now been extended to a full 3-D network-of-zones for a sti rred vessel for single-point dip-pipe addition at any location. This is a s implified computationally tractable approach to fluid mixing, which is supe rior to more complex CFD solutions, because it can easily handle multiple c omplex reactions. The flow and mixing in the 3-D network incorporates axial and radial convection with swirling tangential flow, turbulence and flow a round baffles. Computations are then tractable for long duration semi-batch addition modes of operation. Macro-mixing tin 3-D), the associated partial ly segregated fields of reagents A and B and the spatial-temporal evolution of the local instantaneous yields and selectivities are illustrated using solid-body AVS graphics for the Drain/ICI reactions. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.