Abstract:
To regulate the moisture and glycerol contents in cut tobacco strips effectively during pneumatic drying, the effects of glycerol content and drying temperature on the migration of glycerol and moisture in cut strips were investigated. The drying experiments on cut strips with 0-6.6% glycerol were conducted on a pneumatic dryer with a fixed bed at 100-145 ℃, and the release laws of glycerol and moisture in cut strips were obtained. The results showed that: 1) The migration law of moisture in cut strips was basically unchanged after the addition of glycerol. The influence of initial glycerol content on drying rate of cut strips was minor. The drying process was divided into two stages, the first stage was from 0 to 100 s and the second stage from 100 to 600 s. 2) The surface temperature of cut strips positively correlated to the drying temperature and was independent of the initial glycerol content. 3) The initial content of glycerol had no significant effect on its removal. The loss of glycerol at the first stage accounted for more than 50% of its total loss. At the second stage, the loss rate of glycerol with different initial contents did not differed significantly and decreased with the increase of drying duration. 4) Drying temperature significantly affected glycerol removal. At the first stage, the loss of glycerol at different drying temperatures was about 0.6 percentage point and its loss rate decreased linearly with the drying time, and the change rate of the loss rate negatively correlated with drying temperature. At the second stage, the loss of glycerol increased with the rise of drying temperature, and its loss rate remained essentially constant.