Three-Stage Spray Drying: New Process Involving Instant Controlled Pressure Drop

Abstract

Abstract The goal of this article is to define a new industrial operation called three-stage spray drying that can increase the specific surface area of powder while reducing the amount of fine dust. Because of their compact structure, spray-dried granules have an exchange surface limited to their surface area. We performed experiments inserting the instant controlled pressure drop (DIC®) treatment between the atomization (first stage of spray drying) and the final drying stage. As a high-temperature, short time (HTST) process, DIC treatment expanded granule texture at a rate depending on pore distribution, mesopore volume, and the mean porosity thus generated; the cumulative specific surface area thus induced evolved as a function of the DIC treatment conditions: the higher the DIC steam pressure, the higher the expansion rate. Both specific surface area and mean particle diameter may then simultaneously increase. Technological properties were investigated in order to compare DIC textured powders and conventional spray-dried powders and optimize the treatment; such an optimization can include the rate of decontamination thus generated. Keywords: DICSize particle distributionSpecific surface areaSpray dryingTexture