Solids transportation, heat and mass transfer in rotary dryers

Abstract

In this thesis, the mechanisms of solids transportation, heat and mass transfer within rotary dryers were first examined. Some experimental data obtained in pilot-scale and industrial rotary dryers were used to investigate the influences of moisture content of solids and gas temperature on solids transportation, typically on solids mean residence time distribution, and on heat and mass transfer to estimate the volumetric heat and mass transfer coefficients. One pilot-scale rotary dryer with direct contact between the gas and the solids with co-current flow has been designed, constructed and tested in our laboratory. It mainly consists of four parts: an electric fan, an electric heater, a solids feeding system and a rotary cylinder. Numerous experiments were performed to investigate the dynamic characteristics of solids transportation in this pilot-scale rotary dryer. (Abstract shortened by UMI.)