低中煤级构造煤超临界甲烷吸附特性及吸附模型适用性

摘要

综合分析了低中煤级构造煤甲烷超临界吸附特性,以及常用的吸附理论及其扩展模型对构造煤的适用性.Ⅰ类模型对最大吸附量(Vm)的拟合方差平均值表现为原生＜碎裂＜碎斑＜片状＜揉皱＜碎粒＜鳞片＜糜棱煤,其中T和L-F对原生煤和脆性构造煤的Vm拟合效果较好.Ⅱ类模型对构造煤Vm的拟合方差高于Ⅰ类模型,其中T-BET-1和T-BET-2不适合于鳞片煤.Ⅲ类模型的拟合方差平均值表现为:碎斑＜碎裂＜原生＜碎粒＜揉皱＜鳞片＜糜棱煤,拟合偏差低于Ⅰ和Ⅱ类模型,其中DR1 ～ DR3和DA-3模型可以有效计算鳞片煤和揉皱煤的Vm.DR1～DR3可以较好的反映糜棱煤的Vm.随着构造变形的增强,Ⅲ类模型的吸附饱和度逐渐增高,由单分子层不饱和吸附(原生、碎裂、碎斑),逐渐过渡为单分子层饱和吸附(碎粒、片状煤),再过渡为多分子层吸附(鳞片、揉皱、糜棱煤).原生煤及构造煤吸附势(0 ～ 13 kJ/mol)分布均随着吸附空间的增大而逐渐降低.在达到最大吸附量时,吸附空间表现为:原生≈碎裂＜碎斑＜碎粒≈片状＜揉皱＜糜棱≈鳞片煤.拟合偏差分析表明:E-L,L-F,L和T,对碎粒煤适应性最强;L,F,T和E-L适合于鳞片煤;L,F,E-L,T-BET-3,DR1,DR2适合于揉皱煤;而模型F和T适合于糜棱煤.%The super critical CH4 adsorption characteristics and applicability for commonly used adsorption theories and the extended models Ⅰ-Ⅲ were comprehensively analysed for low-middle rank tectonically deformed coals (TDCs).The mean fitted variances of type Ⅰ models for different TDCs manifest as primary-＜cataclastic-＜mortar coals ＜schistose-＜wrinkle-＜granulitic-＜scaly-＜mylonitic coal,where the model T and L-F have the best Vm-fitted effects for primary-and brittle sequence TDCs.The fitted variances of type Ⅱ models are significantly higher than those of type Ⅰ models and the model T-BET-1 and T-BET-2 are not suitable for scaly coals.The mean fitted variances of type Ⅲ models manifest as mortar-＜cataclastic-＜primary-＜granulitic-＜wrinkle-＜scaly-＜mylonitic coals and are significantly lower than those of type Ⅰ and Ⅱ models,indicating the better applicability than the former two especially the model DR1-DR3 and DA-3 for the Vm of scaly coals and wrinkle coals.The model DR1-DR3 can better reflect the Vm of mylonitic coals.With the enhancements of tectonic deformation,the adsorption saturations of type Ⅲ models transit from monolayer unsaturated adsorption (primary-,cataclastic-,mortar coals),monolayer saturated adsorption (granulitic-,schistose coals) to multilayer adsorption (scaly-,wrinkle-and mylonitic coals).The adsorption potential (0-13 k J/mol) distributions of primary coals and TDCs decrease with the increase of adsorption spaces based on the adsorption potential theory.The adsorption spaces at the maximum adsorption capacity manifest as primary-≈ cataclastic-＜mortar-＜granulitic-≈ schistose-＜wrinkle-＜mylonitic-≈ scaly coals.The fitness biases shows that the models E-L,L-F,L and T are the most applicable for granulitic coals.The models L,F,T and E-L are suitable for scaly coals,models L,F,E-L,T-BET-3,DR-1,DR-2 are suitable for wrinkle coals and model F and T are also the most suitable.