Study of the drying kinetics of the malt bagasse in a pneumatic transporter

Abstract

Malt bagasse is a by-product of the brewing industry that has high moisture, making it very unstable and susceptible to fast microbial deterioration. This work evaluated drying kinetic models of malt bagasse during pneumatic transport with air flow at 30, 45 and 60°C and layouts of 4.5 and 7.0 m. The results showed that the decrease of moisture from malt bagasse was favored at higher air temperature due to the higher diffusion coefficient. In the ranges measured, the values of the effective moisture diffusivity and heat transfer coefficient were obtained between 2.05×10−10 to 12.74×10−10 m2/s and 175 to 363 W/(m2 K), respectively. Average energy for liquid diffusion in the malt bagasse drying process was 44.30 kJ/mol. Pneumatic transport with air flow at 60°C and layout of 7.0 m reached rapidly the final moisture of 12% (w.b.), which may reduce transport costs and allow for long periods of stable storage for malt bagasse. The statistical tests results showed that the experimental data presented excellent fit using the modified Henderson-Pabis model, in the temperature range for both layouts.

Keywords

• brewing industry
• flash pneumatic dryer
• drying kinetic models
• malt bagasse