Analytical Modeling of Counter-Current Drying Process

Abstract

In this analytical study, spray drying of detergent particles of diameters 0.4-1 mm by using counter-current air heated at around 300oC is investigated using Matlab©. Particle drying using hot gases is a mature process with a vast variety of applications ranging from dried food to powdered detergent production. The study shows a strong relationship between the drying process (final water content) and particle size, drying gas temperature, as well as the tower dimensions since cross-sectional area of the tower has a direct control on vertical gas velocity, thus heat and mass transfer coefficients while the height of tower is closely related to residence time of particles in tower which guarantees the targeted drying level. The conclusions of this study can be a guide to have a better set of drying parameters such as inlet temperatures and humidity/water content as well as exit temperatures and humidity/water content and valuable information on how these relate to heat energy consumption necessary to heat the air from atmospheric conditions to the desired drying gas temperature. It is also worth indicating that the measurement of the absolute humidity in tower exhaust is a good parameter to control the drying process in an effective way.