Spray drying: An overview on wall deposition, process and modeling

• Wall deposition indirectly affects the quality of the product and direct economic benefits to the food industry.
• Wall deposition is affected by operating parameters, type and size of the chamber and wall properties.
• Wall deposition modeling is proved to be an effective tool to evaluate the results and reliable conclusions.

The spray drying process is considered a conventional method to convert liquids to powders with some but at an acceptable level of degradation and oxidation of volatile compounds. Spray drying is based on the preparation, homogenization, atomization, dispersion and subsequently dehydration of the solution. Wall deposition is a key processing problem in the spray dryer particles that indirectly affects the quality and quantity of the product. The degree of wall deposition is affected by several factors including operating parameters, type and size of spray dryer and the spray dryer wall properties. The development of wall depositions in the spray dryer deteriorates the yield of the products and hence increases the costs of manufacturing and maintenance. And constructive models are very resourceful in understanding the mechanism of wall deposition which will result in direct economic benefits to the food industry. The aim of this review is to give a physical and chemical description of the wall deposition mechanism and introduce the classified models to simulate and visualize this behavior in spray dryers.