Analysis of fluid flow pattern in a spray dryer to minimizing wall deposition problem

Abstract

Spray drying is one of the widely used processes. The obtained final powder product has specific particle size and moisture content not regarding the dryer capacity and product heat sensitivity. Due to these advantages, spray drying is selected technique for many industrial operations. However, difficulties in spray dryer operation occur as some particles with high moisture content (stickiness) have collected in contacts with metal surface of dryer chamber known as wall deposition problem. Particle deposition, a fluid flow pattern dependent, can be predicted based on a fluid dynamic model. Various developed techniques measure sticky behavior; sticky temperature, Ts, and particle moisture content. An indirect approach correlates between Ts and glass transition temperature, Tg. In general, Tg can be taken as a reference parameter to project the spray drying systems and characterize its properties, including its quality, stability and safety in food systems. Additives agent materials have been used resulting as a reduction of the stickiness and wall deposition in spray dryer. Various studies on spray dryer relied on experiments. However, this information sometimes cannot accurately explain the phenomena within an industrial spray dryer. Mathematical modeling becomes an important tool for process design and synthesis. Most developed models were based on a computational fluid dynamics (CFD) approach in which advanced numerical methods and algorithms are used to solve and analyze the process model equations explaining the fluid dynamics within the process in conducive to the study on wall deposition problem within a spray dryer.