Infrared-convective drying of organic pigments

Abstract

The drying of organic pigments is a challenging assignment due to the complex relationship between heat and mass transfer and the quality attributes such as color, shade, and strength. There is an urgent need to address the drying technology-related issues of this industrially important class of specialty chemicals. The widely used tray dryers and band dryers need further attention due to abysmally low energy efficiency. One of the ways to overcome the longer drying time is to make use of infrared source in addition to convective air drying. The present article discusses the effect of combinatorial IR-convective drying on the quality aspect of organic pigments. The heat and mass transfer rates were analyzed in terms of Biot number to ascertain the role of infrared in bringing down the drying time without compromising the pigment qualities. The mathematical analysis of drying of preformed pellet of pigments was carried out in terms of effective diffusivity, which was obtained in the range of 10-9 to 10-10 m2/s.