Fundamental analysis of particle formation in spray drying

Spray drying is a well established and widely applied technology to manufacture powders for a wide range of applications. However, the production of powders with the desired properties is difficult to achieve using empirical knowledge alone. Therefore scientific based approaches have to be developed to systematically produce particles with the target properties. The purpose of this study is to examine some fundamental principles of particle formation during spray drying and establish a rational methodology to control the particle properties such as size and morphology. The methodology encompasses a mechanistic atomization model to predict the particle size and a guideline based on theoretical fundamentals of particle formation to control their morphology. Both model and guideline were confirmed with experimental investigations of the particle formation process. Spray drying tests were performed in the laboratory to establish a relationship between the theoretical and the experimental results. The fundamental analysis developed was able to anticipate different morphologies and sizes of particles. The spray dried particles showed a particle size within the range of 5 to 10 micron and different morphologies (e.g. shriveled, spherical or inflated shapes). The methodology proposed has allowed the production of particles with different sizes and morphologies in a controlled manner.