微波加热干燥煤泥热质传递及其能耗特性分析

The basic characteristics of the coal slime drying process and its heat and mass transfer characteristics were investigated by microwave heating method, and the basic laws of dynamics and energy consumption changes in different stages were expounded. The results show that the process of microwave drying of coal slime may be divided into three stages, i.e., preheating stage, constant-rate drying stage and decreasing-rate drying stage. The free water within coal slim is removed mainly in the both preheating stage and constant-rate drying stage, whilst the bound water is removed in the decreasing-rate drying stage. The linear model and modified Page Ⅰ model can be used to describe the corresponding kinetic processes in the constant-rate and decreasing-rate stage, respectively. Furthermore, the apparent activation energy of the selected sample in the decreasing-rate stage is obtained as 3.23 W/g. The energy consumption in the constant-rate drying stage ranges from 2.94 kJ/g to 5.90 kJ/g, which is significantly lower than that in the preheating or decreasing-rate drying stage. The energy consumption is decreased gradually with the increase of microwave power ranging from 500 W to 800 W or initial mass from 150 g to 300 g.