不同煤化程度煤尘水分复吸特性及平衡预测模型研究

Study on moisture re-absorption characteristics and equilibrium prediction model of coal dust with different rank

水分复吸是一种有效评价煤尘润湿性大小的方法,但不同类型煤尘的亲水性强弱存在差异。为了探究不同煤化程度煤尘水分复吸特性,通过自行设计水分复吸试验系统,对比分析不同煤尘在不同环境温度和相对湿度条件下水分复吸率变化规律,明确煤尘特性对水分复吸特性的影响,从而确立不同煤化程度煤尘水分复吸平衡预测模型。研究结果表明:随着环境温度升高,煤样水分复吸率先增大后减小,达到复吸平衡的时间在逐渐缩短;在相同温度条件下,相对湿度增加会提高煤尘水分复吸能力,水分复吸平衡时间与相对湿度成正比;煤化程度越高,其水分复吸能力越强。随着煤尘接触角增大,水分复吸率与接触角成线性反比关系,煤尘的润湿性与水分复吸能力成正相关线性关系;含氧官能团占比增加,水分复吸率整体上呈线性增加的趋势;煤尘比表面积增大会抑制水分复吸过程,而孔径增加会促进吸附水的储存,总孔体积增大会为复吸水提供更多的空间,因此可以根据煤尘特性参数有效预测不同煤化程度煤尘的水分复吸率及润湿性大小。通过对比分析各预测模型的拟合结果,发现Henderson模型是所有预测模型中拟合度最高的,最适合不同煤化程度煤尘水分复吸平衡的精准预测模型。研究将有助于不同煤尘吸湿性大小的定性分析,为煤尘润湿降尘技术研究提供借鉴。

Moisture re-absorption is an effective method to measure wettability of coal dust,but for different types of coal dust,there are difference in their hydrophilicity.In order to explore the moisture re-absorption characteristics of coal dust with different degrees of coalification,the variation of moisture re-absorption rate of coal dust under different ambient temperature and relative humidity was compared and analyzed by a self-designing moisture re-absorption experimental system.The effect of coal dust properties on moisture re-absorption characteristics was clarified,and a prediction model for the moisture re-absorption equilibrium of coal dust with different degrees of coalification was established.The results showed that,with the increase of ambient temperature,the moisture re-absorption rate of coal sample firstly increased and then decreased,and the time to reach the re-absorption equilibrium was gradually shortened.In the same temperature condition,the moisture re-absorption rate of coal dust increased with increasing relative humidity,and the time to reach moisture re-absorption equilibrium was proportional to relative humidity.The higher the degree of coalification led to the stronger moisture re-absorption capacity.As the contact angle of coal dust increased,the moisture re-absorption rate was linearly inversely related to the contact angle,and the wettability of coal dust was positively linearly related to the moisture re-absorption capacity.The moisture re-absorption rate overall increased linearly with the increasing proportion of oxygen-containing functional groups.The increase of specific surface area of coal dust will inhibit the moisture re-absorption process,while the increase of pore size will promote the storage of adsorbed water,and the increase of total pore volume will provide more space for moisture re-absorption.The moisture re-absorption rate and wettability with different coalification can be effectively predicted based on the characteristic parameters of coal dust.By comparing and analyzing the fitted results of each prediction model,it was found that the Henderson model had the highest fitting degree among all the prediction models and was the most suitable for accurate prediction of moisture re-absorption equilibrium of coal dust at different coalification.The results will help to qualitatively analyze the hygroscopicity of different coal dust and provide a reference for coal dust wetting and reduction techniques.