褐煤负压干燥动力学研究

Study on the drying kinetics of lignite under negative pressure

运用真空干燥箱,进行了不同压强、不同温度组合下的褐煤负压干燥试验研究,根据煤样含水率与干燥时间之间对映规律,提出一个简单数学模型,并引入干燥压强、干燥温度有关的系数k、m,得到褐煤负压干燥的动力学方程X=X_(0e)^(-kt)~m及干燥速率方程dX/dt=X_(0e)^(-kt)~m(-kmt^(m-1));另外,对干燥温度和压强对煤样终点含水率的影响进行了分析探讨,结果表明:使煤样水分能够彻底脱除的煤内孔隙半径均在纳米级,环境压强越小、温度越大,煤样最终含水率越小,说明煤中存在大量盲孔,小的外输能量(压力梯度、温度梯度)不足以使盲孔破裂。

Drying behaviors of lignite were studied with a vacuum drying oven under different pressures and temperatures in this study. A mathematical model was established according to the curves of the water content for different drying times to explain the kinetics of lignite drying. Further analysis explained the influence of pressure and temperature on final moisture content. The result suggests lower pressure and higher temperatures cause smaller final moisture contents, which indicates the existing of abundant blind holes in coal and the pressure and temperature gradients should be large enough to rupture the blind holes.