关于确定兰氏体积和兰氏压力的方法

A method for determining Langmuir′s volume and Langmuir′s pressure

兰格米尔(Langmuir)等温吸附方程,是描述页岩吸附气量或煤层吸附气量与压力的重要方程。兰氏方程中的兰氏体积(Langmuir′s Volume)和兰氏压力(Langmuir′s Pressure)是2个重要常数。不同页岩层或煤层的吸附气量各异,而且具有不同的兰氏体积和兰氏压力。据国内许多文献报道,目前在我国确定兰氏体积和兰氏压力的方法是经验取值法,这种方法就是将实验测试的最大吸附气量作为兰氏体积,再将与二分之一最大吸附气量相应的压力作为兰氏压力。该经验取值法没有任何理论依据,所得到的结果是不正确的。该文根据兰氏方程提出了确定兰氏体积和兰氏压力的线性回归法。实例应用表明,经验取值法与实测数据相差明显,而线性回归法与实测数据吻合得很好。

Langmuir′ s isothermal adsorption equation is a function describing the adsorption contents of shale or coal bed. In this equation, Langmuir′ s volume and Langmuir′ s pressure are two very important parameters. For different shale bed or coal bed, the adsorbed gas contents are different. According to the report of references, the determination of these two parameters is through empirical value-picking method in China. The maximum adsorption content is Langmuir′ s volume and Langmuir′ s pressure is the pressure corresponding to the half maximum adsorption content. This method is not proper and the result is not reliable. With the linear relationship of Langmuir′ s function, Langmuir′ s volume and Langmuir′ s pressure are determined by linear regression. Through two example applications, it is shown that this method is perfectly fitted to the experimental test results and the experience method is very poor fitted.