深部煤层超临界甲烷吸附量预测研究

Prediction of Supercritical Methane Adsorption in Deep Coal Seam

为了预测深部煤层超临界甲烷吸附量,构建了吸附势模型与等量吸附热模型,探究了这2种模型在预测超临界甲烷吸附量时的误差。根据温度300.5 K和323.0 K条件下的等温吸附数据,分别应用2种模型预测了温度313.0 K条件下的超临界甲烷吸附量,并与实测值进行对比,结果表明:研究超临界吸附时要修正压力;等量吸附热模型可应用在超临界吸附领域,当压力为6.0~7.5 MPa时,吸附量预测值平均相对误差为3.17%,吸附势模型预测值平均相对误差为3.60%;随着压力的增加,吸附势模型预测误差逐渐减小,而等量吸附热模型预测误差呈增大趋势;当压力小于6.99 MPa时,等量吸附热模型预测误差较小;当压力超过6.99 MPa时,吸附势模型预测效果较好。综合分析预测结果,2种模型的预测误差均在工程允许误差范围以内,而吸附势模型计算过程简单、需要的数据较少,在工程应用领域适用性更好。

In order to predict the supercritical methane adsorption in deep coal seam,the adsorption potential model and the equal adsorption heat model were constructed. The error of this two models in predicting the supercritical methane adsorption was investigated. According to isothermal adsorption data at the temperature of 300. 5 K and 323. 0 K,the supercritical methane adsorption at the temperature of 313. 0 K was predicted by two models respectively,and compared with the measured values. The results showed that the pressure should be corrected in the study of supercritical adsorption; the equal adsorption heat model can be used in the field of supercritical adsorption,the average relative error of the equal adsorption heat model is 3. 17% and the average relative error of the adsorption potential model is 3. 60% when the pressure is from 6. 0 MPa to 7. 5 MPa; with the increase of pressure,the prediction error of the adsorption potential model decreases gradually while the prediction error of the other model is increasing; when the pressure is below 6. 99 MPa,the equal adsorption heat model is better in prediction; when the pressure is beyond 6. 99 MPa,the adsorption potential model about prediction result is better. In totally,the prediction error of two models are within the engineering allowable error range,but the adsorption potential model is simple and requires less data,and it has better applicability in engineering application.