Response And Mechanism Of Step-extracted Vitrain To Supercritical Methane Adsorption

There have been step-extraction-experiments on the 5 sets of coals collected from western Guizhou and Eastern Yunnan. The main experiment methods are traditional organic solvent extraction method and ultrasonic oscillations technology, in which CS2, benzene, acetone and tetrahydrofuran are used as extraction solvents. The physical characteristics, composition and structure of raw coal, extract and extracted residue are analyzed. The isothermal adsorption and desorption experiment of vitrain and extracted residue are completed under the equilibrium water condition in order to show the supercritical adsorption response of vitrain step-extraction and its mechanism.The extraction yield, group component of extract and evolution characteristics of extracted residues micro-crystallite structure of different solvents for different rank coals are discussed, and the evolution with different extraction yield and coal rank are analyzed. The relationship between extraction yeild and pore structure of vitrain are preliminarily discosed. The natural classification of pore structure tested by fluid nitrogen are put forward. The pore and connectivity are dicussed from extraction start to finish. The change and effect factor ofζelectric potential of raw coals and their extracted residues are analyzed.On the basis of these, the methane adsorption of raw coals and their extracted residues under supercritical condition are described. It is discovered that traditional isothermal adsorption equation can be used to fit methane isothermal adsorption curve under reservoir conditions. The free energy, adsorption potential and adsorption energy of theirs are calculated under 30℃. The volume of methane adsorped and free energy of raw coals and their extracted residues are predicted according to the characteristics that the adsorption character curve is single. The difference of adsorption ability of raw coals and their extracted residues are explained with thermodynamics theory. The relationship between raw coals and their extracted residues and strata setting and coal permeability are analyzed. There are 218 maps, 21 tables, and 130 references in this paper.