Lignite drying with steam tube rotary dryer and its heat transfer characteristics

The steam tube rotary was used to test heat transmission characteristics of lignite under different drying conditions.The results show that,remaining the rotational speed constant,when the coal feed increase from 79.04 kg/h to 132.5 kg/h,the heat transfer coefficient first increase from 35.94 W/（m2·K） to 36.83 W/（m2·K）,then reduce to 33.34 W/（m2·K）.Adopting the same coal samples,the heat transfer coefficient first increase,then decrease when the rotational speed raise from 0.5 r/min to 3.7 r/min,that means there is an optimal rotational speed.The tests provide data foundation for the calculation of heat transmission coefficient.Its influencing factors are also investigated using dimensional analysis methods and heat transfer correlation mathematical models.The key parameters of heat transmission model a,b,c is 0.036,0.14 and 19.77.The model provides reference for relevant engineering design.