A sustainable production in sugar industries : study of an improved vacuum pan performance through numerical simulations

This paper presents at improving existing vacuum pan (large cylindrical vessels with vertical heating surfaces) operation through numerical simulations, in particular for the sugar industries, and at enhancing the competitiveness of Australian industries. Therefore, this study investigates a Computational Fluid Dynamics (CFD) model for a single air bubble rising in non-Newtonian polymeric and crystal suspension. The bubble rise characteristics through different stagnant liquids in a vertical cylindrical column are modelled using the CFD code Fluent. Air bubble rise dispersed into the continuous liquid phase has been considered and modelled for two different bubble sizes. Bubble trajectory and velocity distributions were captured through a surface-tracking technique i.e. Volume of Fluid (VOF) method by solving a single set of momentum equations and tracking the volume fraction of each fluid throughout the domain. The simulated results of the bubble flow contours were validated by the experimental results and literature data. The model developed is capable of predicting the entire flow characteristics of different sizes of bubble inside the liquid column. The simulated data is used in sugar industries to gain knowledge, optimise and develop improved vacuum pan design that can achieve more productive performance and result in improved steam economy. The possible modification of the vacuum pan design enhances the sugar industry’s competitive edge in the global market place by reducing production cost and less green house gas emissions.