Particle drying and crystallization characteristics in a low velocity concurrent pilot scale spray drying tower

A low velocity spray tower was built in Monash which allows the production of mono-dispersed particles. As part of a larger project in controlling the functionality of the particles produced, the computational fluid dynamics technique (CFD) was used to gain more insights into the drying characteristics of the mono-dispersed droplets. Introduction of droplet and mass transfer did not significantly alter the flow field. Analysis revealed that the wet bulb region was significant in this tower. Varying the inlet air temperature from 100 °C to 180 °C resulted in contrasting drying history. These drying kinetics were then extended to assess the in-situ crystallization phenomenon. For this spray drying tower, it was found that lower inlet temperature condition favoured a higher degree of crystallinity.

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► CFD simulation of a unique low velocity spray drying tower.
► Contrasting drying history is achieved: high moisture and low temperature/low moisture and high temperature.
► Low drying temperature might induce higher degree of in-situ crystallization.