不同煤种低温干燥特性的实验研究

Experimental Investigation of Low-temperature Drying Characteristics of Different Coals

利用热天平对4种不同煤样进行了等温干燥脱水实验,实验表明:对于同一煤样,温度升高会导致煤样干燥速率增大。不同煤样、不同温度的干燥速率曲线趋势基本一致,经历升速干燥阶段、恒速干燥阶段和降速干燥阶段。对干燥实验数据使用薄层干燥模型理论中的15种不同模型进行数据拟合,计算并比较不同模型的相关系数从而确定了Yagcioglu模型为等温干燥最为适宜的机理模型。在最佳干燥机理模型的基础上进行动力学分析,在相同干燥温度条件下,干燥速率常数k随着煤样含水量增加而减少,而在同一煤样中,k则呈现出随着干燥温度升高而增加的趋势。4种煤样在低温情况下等温干燥的表观活化能分别为E_(CZ)=37.40 kJ/mol、E_(TS)=28.41 kJ/mol、E_(DF)=53.52 kJ/mol和E_(HY)=33.53 kJ/mol。

The isothermal dehydration experiments of four different coal samples were conducted by heat balance,and the experiments indicated that the drying rate will increase with temperature for the same coal sample. The drying rate curves of different coal samples or different temperatures were basically the same,including speed-up drying stage,constant speed drying stage and speed-down drying stage. Data fitting was performed according to fifteen different models in the theory of thin layer drying. Yagcioglu model was selected as the most appropriate model for isothermal drying procedure through calculating and comparing the correlation coefficients of different models. Based on the optimal drying mechanism model,the dynamic analysis was carried out. The results showed that the drying rate constant k decreases as the moisture content increases at the same drying temperature,and it increases with the drying temperature for the same coal sample. For the four coal samples,the apparent activation energy of isothermal drying at low temperature was E_(CZ)= 37. 40 kJ / mol,E_(TS)= 28. 41 kJ / mol,E_(DF)= 53. 52 kJ / mol and E_(HY)= 33. 53 kJ / mol,respectively.