Determination of spray-drying kinetics in a small scale

• Published in: Drying technology 2005-01, Vol.23 (8), p.1751-1759
• Main Authors: Zbicinski, I, Piatkowski, M, Prajs, W
• Format: Article
• Language: English
• Subjects: air temperature; Critical moisture content; dewatering; evaporation rate; heat transfer; High evaporation rate; kinetics; Laboratory scale; laboratory techniques; maltodextrins; mass transfer; spray drying; water activity; water content
• ISSN: 0737-3937; 1532-2300
• DOI: 10.1081/DRT-200065197

The main aim of the study presented in this article was to develop and test a method to determine spray-drying kinetics in a laboratory scale. A special measuring tunnel to obtain evaporation rate similar to the conditions observed in a spray-drying column was designed, built and tested. Extensive studies of drying kinetics for maltodextrin were performed for different air flow rates and air temperatures. Test runs to determine repeatability of this technique showed satisfactory agreement between subsequent measurements, which confirms accuracy of the developed measuring method. An effect of the initial moisture content on the critical moisture content was observed which is related to a decrease of the equilibrium vapor pressure over the solution and a decrease of the driving force of evaporation and drying rate of the process. Results of the experiments proved that the generalized drying curve obtained from small-scale experiments could be used to describe spray-drying kinetics if the critical moisture content of the material is known.