NUMERICAL SIMULATION OF FLUIDIZED BED DRYING OF PHARMACEUTICAL POWDERS USING A TWO-PHASE MODEL
Date
2023-07-11
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0008-9745-5904
Type
Thesis
Degree Level
Masters
Abstract
Tablet production in the pharmaceutical industry is a common process for oral ingestion products. Before tablet production, mixtures of active pharmaceutical ingredients and other excipients are granulated, generally through the process of wet granulation. The wet granulation process agglomerates mixtures of powder components to create homogeneous granules, typically using water as a liquid binder. Before the wet granules can be made into tablets, they have to be dried to an acceptable level. Fluidized beds have been extensively used for the drying of these granules. To better understand the fluidized bed process, mathematical models have been created to emulate the drying phenomena. Simplified models, such as phenomenological models, aim to capture the drying characteristics without defing the more complex kinetics and thermodynamics of the system. A recent approach based on a two-phase model is further verified in this work using experimental data from a lab scale fluidized bed. The model was examined against the pharmaceutical powder moisture content and temperature profiles from previous experimental work.
The model is comprised of the mass and energy balances of five distinct sections of the fluidized bed. Powder moisture and heat transfer are governed by a stagnant gas film in equilibrium with the surrounding gas. The model shows good correlation with the experimental data. It also displays the general characteristics of pharmaceutical powder drying, with distinct constant drying rate and falling drying rate periods.
Upon model validation, optimization of the inlet gas parameters is explored. Optimization of the model is imple- mented, controlling the inlet gas parameters and incorporating a stepwise change during the drying process. It was found that a single stepwise change has a negligible effect on optimizing the process but is still useful around the end point of the batch. In addition, optimization results and behaviours are discussed.
Description
Keywords
Fluidized Bed Drying, Fluidized Bed Modeling
Citation
Degree
Master of Science (M.Sc.)
Department
Chemical and Biological Engineering
Program
Chemical Engineering