Study on heat and mass transfer of flexible filamentous particles in a rotary dryer

• A mathematical model of heat and mass transfer in rotary dryers is established.
• Moisture content of flexible filamentous particles and gas in dryers can be studied.
• Relation of temperature and humidity of tobacco and hot gas can be analyzed.

Rotary dryers are of significance to a wide range of industries to process flexible filamentous particles, such as chemicals, food and tobacco. However, heat and mass transfer of flexible filamentous particles in the rotary dryer have not been studied deeply. In this paper, a mathematical model of heat and mass transfer in a rotary dryer is established. The influence of moisture content and humidity on flexible filamentous particles and hot gas in the rotary dryer is studied, as well as the differences of temperature and humidity of particles and hot gas after entering the dryer. In a counter-current cascading rotary dryer, results show that dehydration of flexible filamentous particles in the lower end of the dryer is significantly higher than that of the upper end under the same drum wall temperature. Heat of flexible filamentous particles and gas flow are likely to increase. Most heat of gas flow come from the latent heat of vaporization in particles. Results on temperature and humidity of particles under different operating conditions can be obtained, and then suggested an optimum condition.

Heat and mass transfer processing in a rotary dryer.Heat and mass transfer of cut-tobacco particles occurred in the rotary dryer. Shown are the hot gas and particles in a counter-current cascading rotary dryer, and the hot gas at the top of dryer, while cut-tobacco particles in the bottom. Heat transfer from wall to particles and wall to hot gas when the temperature of wall was higher than the hot gas were researched in this paper. Mass transfer between hot gas and cut-tobacco particles in the rotary dryer was also studied.Figure optionsDownload as PowerPoint slide