Abstract:

The drying characteristics under isothermal condition of Hulun Buir pulverized brown coal with high moisture content of 40% was studied using thermo-gravimetric method. The effects of drying temperature and particle size on drying process were analyzed. The results showed that the constant rate stage was obviously observed, and the characteristics were closely related to drying temperature and free water content. The critical (MC_cr) and equilibrium (MC_eq) moisture content were obtained. The drying rate decreased with the decrease of particle size, but the effect of particle size was not obvious when the coal particle was enough small. MC_cr and MC_eq decreased with the increase of temperature, however, MC_cr increased and MC_eq decreased slightly with the decrease of particle size. The experimental results could provide a basis of selection and optimization of brown coal powder and drying process.

Key words: pulverized brown coal, drying temperature, particle size, constant rate stage, critical moisture content

摘要：

以水分含量高达40 %的呼伦贝尔褐煤煤粉为实验物料,利用热重法研究了等温条件下的干燥特性,对比分析了温度、颗粒粒度对干燥过程的影响。实验结果表明,呼伦贝尔褐煤干燥过程具有明显的恒速干燥阶段,其特征与干燥温度和自由水含量密切相关。获得了呼伦贝尔褐煤煤粉在不同温度和粒度条件下的临界含水量(MC_cr)和平衡含水量(MC_eq),发现随着颗粒粒度的减小,褐煤煤粉干燥速率略有增大,但当粒度较小时,粒度因素对干燥过程的影响不明显。MC_cr与MC_eq均随温度的升高而减小,而随着颗粒粒度的减小,MC_cr略有降低,MC_eq略有增大。实验结果可以为褐煤制粉干燥工艺条件的选择和优化提供依据。

关键词: 褐煤煤粉, 干燥温度, 颗粒粒度, 恒速干燥阶段, 临界含水量