Drying process optimization and kinetic study of sugarcane filter cake using a pilot-scale rotary dryer

Abstract

In this study, a pilot-scale countercurrent hot air rotary dryer was used to reduce the moisture content of the sugarcane filter cake. Rotary dryers allow the use of bulk feedstock at high temperatures with short drying times. The response surface methodology was used to optimize and evaluate the effect of hot air temperature and rotational speed on drying efficiency, based on the central composite design. Various temperatures (70, 100 and 130 ℃) and rotation speeds (1, 3 and 5 RPM) were investigated. High drying efficiency was achieved by using high hot air temperatures and low rotational speeds. The error between the model and the experiment was less than 5%. Additionally, seven mathematical drying kinetic models were investigated to describe the drying characteristics of sugarcane filter cake samples. The best-fitted model for the three temperatures considered was the Page model, as assessed by the coefficient of determination (R2), average relative error percentage (P), reduced chi-square (ꭓ2), and root mean square error (RMSE) (R2 = 0.978-1.00). The results demonstrate that the optimization models may be considered for application in an industrial rotary dryer at 70–130 ℃, using the exhausted gas from a power plant stack.