不同变质程度煤的吸附能力与吸附热力学特征分析

Analysis on Adsorption Capacity and Adsorption Thermodynamic Characteristics of Different Metamorphic Degree Coals

以4种不同变质程度的煤为研究对象,在实验室基础参数测定和不同温度下的吸附试验基础上,利用Langmuir吸附动力学方程和热力学理论,构建了表面自由能变化值和等量吸附热的三维计算模型,进而分析了不同变质程度煤的吸附能力与吸附热力学特征。结果表明:煤的表面自由能变化值随着压力的增加先迅速增加后缓慢增加,随着温度的增加而减小,煤的表面自由能变化值从大到小依次为焦煤、肥煤、长焰煤、无烟煤,单位面积的吸附量随着变质程度的变化关系也是如此;煤的吸附能力和比表面积均呈现先减小后增加的U型趋势,从大到小依次为无烟煤、长焰煤、肥煤、焦煤,煤的变质程度主要是通过比表面积来影响煤的吸附能力;煤的等量吸附热随着吸附量的增加而变大,随着温度的升高也变大,初始等量吸附热随变质程度的增加而逐渐增加,从大到小依次为无烟煤、焦煤、肥煤、长焰煤。

Taking four different metamorphic degree coal samples as the study objects,based on basic parameters and different temperature adsorption experiments,the paper used the Langmuir adsorption dynamics equations and thermodynamic theory to build three-dimensional calculation models of change value of surface free energy and isosteric heat of adsorption respectively.Then adsorption capacity and adsorption thermodynamic characteristics of different metamorphic degree coals were analyzed.The results showed that the change value of surface free energy increased rapidly with increasing pressure at first while increased very slowly at last,however,it would decrease with increasing temperature.The change value of surface free energy from large to small in order was coking coal,fat coal,long-flame coal,anthracite coal, and the adsorption capacity of per unit area was also in this order.The trends of specific surface area and adsorption capacity were both in U type in order that anthracite coal,long-flame coal,fat coal,coking coal,so the specific surface area was the main factor which influenced the adsorption capacity of different metamorphic degree coals.The isosteric heat of adsorption increased with increasing adsorption volume and temperature respectively,and the initial isosteric heat of adsorption increased with increasing metamorphic degree of coals in order that anthracite coal,coking coal,fat coal,long-flame coal.