(341c) Scaling Continuous Powder Blenders: The Length-Scale Problem

With growing adoption of pharmaceutical continuous manufacturing, understanding transferability of processes between manufacturing lines is becoming of critical importance. This comprehension facilitates tech transfer of processes between lines of similar or dissimilar scales hosted at different sites or to or from a CDMO. Development of robust, science-based approaches to facilitate the transfer of continuous processes is key to growing adoption of the technology.

Powder blending is a critical unit operation in pharmaceutical manufacturing of oral dose products. Blending in continuous processes is most commonly performed in tubular blenders. These blenders, fitted with an impeller facilitate mixing along two length-scales – radial and axial. Substantial progress has been made in understanding how powder mixing scales on the radial axis, that is how mixing scales in blenders of increasing diameters. However, little is understood on how mixing scales along length of the blender. This work attempts to understand mixing progression along the axial direction of a continuous powder blender.

This examination is performed by leveraging experiments on two inclined continuous powder blenders of different lengths but the same diameters. Two powder throughputs are explored in combination with three different blade configurations. Blending performance is measured by virtue of measuring the mass holdup, mean residence time and the number of blade passes. Early work on understanding axial dispersion along the length is also discussed.