CFD Simulation of a Pharmaceutical Bubbling Bed Drying Process
Drying is one of the major unit operations in the manufacturing of solid pharmaceuticals. In many pharmaceutical processes, the optimum design of the drying process will significantly enhance the rate and reliability of the production and, in turn, decrease the cost of the pharmaceutical products. Consider a cone-shaped batch fluidized bed drying process with bottom (inlet) and top (outlet) diameters of 0.08 m and 0.19 m, respectively. Pharmaceutical granulated spherical particles with 1200 kg/m3 density, 287 pm diameter, and 0.0417 kg water/kg dried solid initial moisture content were placed initially in the bed. To remove water from the particles, a stream of high temperature air with 5 m3/h flow rate and 50 °C temperature was introduced. The fluidized bed is operating in a bubbling regime. The critical moisture content (Xcr) that separates the two drying rate periods (namely, the constant rate period and the falling rate period) was estimated to be 0.012 kg water/kg dry solid.