Simulation of convective drying of multicomponent moisture in a computer code MultidryPAK

摘要

Drying of solids containing multicomponent moisture is common and important in high-tech industries like production of pharmaceuticals, magnetic storage media etc., yet it is neglected in present day process simulators. The reason is that the process is poorly understood due to it's complexity and the fact that it requires specialised tools for solving problems encountered in this area. On the other hand drying in neglected in specialised texts on multicomponent mass transfer (e.g. Taylor, Krishna, 1994). The diffusional resistance characteristic to evaporation to inert gas influences selectivity of the process otherwise governed by relative volatility alone. This makes the predicting of the process more difficult as a new type of azeotropes i.e. dynamic azeotropes emerge, defined not only by the relative volatilities but also by the multicomponent diffusional mass transfer. Main goal of calculations is either to simulate the process of drying for specified initial conditions or to predict stationary points and their zones of influence (selectivity maps). These goals can be reached with computer code MultidryPAK (MdP) that was written for this purpose. Construction parts of the program are described below.