Drying kinetics of coated sodium percarbonate particles in a conical fluidized bed dryer

• The best model for description of drying kinetics of coated sodium percarbonate particles is presented.
• Experiments are conducted in three different level of inlet air temperature and three different level of air flow rate.
• Fifteen models are used for describing the drying kinetics of sodium percarbonate.
• The modified Henderson and Pabis model and two term model are considered as the most appropriate.
• The effective diffusivity and activation energy are calculated for sodium percarbonate particles.

Sodium percarbonate is a white powder that is used as bleach in detergent industries. Because of its sensitivity to environment and tendency to maintain the strength of bleaching action, it needs to be coated. Therefore, the drying of the coated sodium percarbonate particles is the main stage of their production process. In this study, the kinetics of the drying process of coated sodium percarboanate particles is investigated using a particle fluidization method and a conical fluidized bed dryer on a laboratory scale. The experiments are conducted at the inlet air temperature of 60, 70, and 80 °C and the air flow rate of 90, 100, and 120 m3/h. Then, some of the widely used drying models are fitted to the experimental data of the moisture ratio. The fit quality of the models is determined using the coefficient of determination (R2), root mean square error (RMSE), and reduced chi – square (χ2). Among the considered models, the ʻModified Henderson & Pabisʼ model with average R2 = 0.988204 and the ʻtwo termʼ model with average R2 = 0.985082, under almost all operating conditions, and the model developed by Verma et al. with average R2 = 0.971698 at high flow rate and high temperature are selected as the best models. In the drying process of coated sodium percarbonate particles, the effective diffusivity varies from 2.2337 × 10− 10 to 22.0648 × 10− 10 m2/s.

In this study, the drying behavior of coated sodium percarbonate particles was investigated and was modeled using a batch fluidized bed dryer. The results revealed that the modified Henderson and Pabis model and the two term model under almost all operating conditions, and the Verma et al. model at a high flow rate and temperature, fitted very well with the experimental data.Figure optionsDownload as PowerPoint slide