Design, simulation, and performance of a draft tube spout fluid bed coating system for aerogel particles

A draft tube spout fluid bed coating system was designed to coat porous aerogel particles in a size range from 0.1 to 2 mm in diameter. Its primary objective was to insure that just the outer surface of the particles was coated. The inner, pore surface area of the particles needed to remain open to preserve their insulating properties. This paper discusses the design, simulation, and experimental results we obtained on the actual coating of 1–3 mm particles. A conventional, pharmaceutical coating, Surelease®, was used as the coating material and the system successfully coated the particles without penetration of the coating material into the particles. The apparatus can be used to coat friable, low density particles as well as those of high density and is well suited for other coating applications including those in the pharmaceutical industry.