(274c) Investigating Continuous Powder Blending at Different Scales Using Residence Time Distribution Studies
- Conference: AIChE Annual Meeting
- Year: 2017
- Proceeding: 2017 AIChE Annual Meeting
- Group: Pharmaceutical Discovery, Development and Manufacturing Forum
Tuesday, October 31, 2017 - 8:44am-9:06am
In this work, continuous powder lubrication performance was compared using continuous dry powder blenders at both lab scale and production scale by varying total mass flow rate and blender blade speed with a view to translating the lubrication performance between blender systems. At steady state, the RTD and residence mass hold-up in the blender were measured. The tensile strength of tablets compacted from the blend at steady state were also measured in order to characterize the lubrication response.5 Three different regimes of blending were observed with increasing blade speed â âmixingâ, âtransitioningâ followed by âconveyingâ. Peclet number (Pe# - ratio of axial transport to axial dispersion) was determined by fitting RTD curves using the axial dispersion model. A slower line rate was required at the lab scale in order to achieve the same Pe# at production scale. The mean residence time, Ï, was found to be the key predictor of lubrication performance, independent of blender scale. For both blender systems, Ï decreases with increasing mass flow rate and increasing blade speed and, where blender speed was increased, changes in Ï were minimized by selecting higher mass flow rates. Longer Ï produced greater variation and skewness of the RTD across each blending system which has implications for material tracking and product yield within any continuous manufacturing process.Â Significantly, we show that the mean residence time, Ï can be calculated directly from knowledge of the residence mass hold-up and mass flow rate for both systems.
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