A novel method for vacuum belt drying process optimization of licorice

A novel prediction method was developed to optimize the operating parameters of the vacuum belt drying (VBD) process of licorice extract. A numerical simulation model containing the boiling and evaporation models was firstly established to predict the product moisture of the process. To improve the accuracy of the numerical simulation, a transition model connecting the boiling and evaporation processes was introduced. This numerical model was validated by both lab-scale and industrial production experiments, with the MSE value of 2.176 × 10−3 and 6.58 × 10−5, respectively. The predicted moisture content can be used to evaluate product properties and help to avoid over drying and energy waste. Further, the predicted moisture content can be used to adjust process parameter conditions. Based on the numerical simulation, a decision-making approach was developed to predict optimal operating conditions to dry products with desired final moisture content. Three critical process parameters were determined based on their impact on production efficiency. As a result, the conveyor belt speed was found to play the most crucial role in the VBD process. The model can be used to provide precise operating conditions for VBD to replace traditional empirical adjustment method.