Influence of operation parameters on process stability in continuous fluidised bed layering with external product classification

Abstract Several studies—theoretical and experimental—show that continuous fluidised bed layering granulation with external classification can show instability in the form of self-sustained oscillations. Recent results show that the process stability does not only depend on product-related process parameters but also on the formation of functional zones in the fluidised bed chamber, especially the formation of a spray and drying zone. In this work a systematic evaluation of zone formation in different apparatus designs (e.g., top- and bottom-spray in cylindrical apparatuses) and its influence on process stability is performed, resulting in a stability regime map for the different apparatus designs and key operation parameters.