The consumption of exergy for lignite drying with different technologies: a comparative theoretical study

[EN] Pre-drying is an effective method to upgrade lignite and broaden its utilization areas. Various drying technologies could be applied to pre-dry lignite. The drying temperature in these drying technologies are different, which means that energy at different grades is used in these dryers. To analyze the irreversibilities of drying process, the exergetic analysis models are developed in this study. The exergy feeding and consumption rates are defined as the indicators. Various lignite drying technologies are calculated and quantitatively compared. Results show that exergy consumption rate for steam fluid-bed dryer is the smallest, which is 432.6 kJ (kg H2O)-1.