| Injections of carbon dioxide into coalbeds can both enhance coalbed methane recovery (ECBM), a high-efficiency energy, and realize underground storage of CO2. The diffusion and sorption of methane and carbon dioxide are key dominant processes. In order to assess the viability of a possible ECBM recovery operation, adsorption data are required to estimate the capacity of the coal, the adsorption of binary and ternary mixtures of CO2,CH4, and H2O on coal has been more and more investigated recently both experimentally and theoretically. Whereas information about competitive adsorption of these gases is a prerequisite to describe the dynamics in the coal seam. While the interaction about adsorption of the mixtures is still scarce. Molecular simulation can provide a general method to explore various natural processes at the molecular level to study on the interplay between coal macro-molecule and small gas molecules in atomistic-level. In the present study,the adsorption properties of three important gases in coal were simulated using molecular simulation, in an attempt to shed light on the details of adsorption at the atomistic level and to demonstrate the possible use of this common technique in the field of coal gas interaction. This article adsorption of molecular simulation techniques selected Hami coal inertinite structure and its relationship with the study of gas adsorption for coal bed methane resource projections, and other microscopic mechanism of adsorption to provide the necessary theoretical basis.The main conclusions are as follows:(1) The modeling for HI was completed with analyzing the 13C CP/MAS NMR spectra to obtain related parameters and elemental distribution, and has been adjusted by consistent with practical spectra.(2)Based on annealing molecular dynamics simulations, the optimized structure of three-dimensional flaky HI have been found, the overall trend in the "graphite." It is that van der Waals force is the main force, HI density is 1.29g/cm3.(3) Based of grand canonical Monte Carlo (GCMC) simulation method, saturated adsorbance of CH4, CO2, H2O were respectively:3,5,11 moleculars/ uc; location visualization CH4 preferentially adsorbed near the benzene ring, CO2 between two cross arrangement, H2O prone to the oxygen groups of coal. Based on molecular dynamics simulation under the temperature 298.15K and a series of pressure,the absorption properties of HI, adsorption is a dynamic equilibrium,have been attained. The porosity model for coal suggests that gas transport occurs in two stages:initially, gas moves through macropores/cleats by diffusion dominated by molecule-molecule collision under low-tension, and then gas moves through micropores by surface diffusions as pression escalate.(4) Based of grand canonical Monte Carlo (GCMC) simulations under the temperature 273.15-323.15K,0-20MPa pressure,the adsorption properties that pure component Langmuir volume (VL) of the size as H2O>CO2> CH4, adsorbance and fugacity not completely meet the Langmuir equation; adsorption capacity increased with the increase of pressure; adsorption capacity decreases when the temperature raise have been obtained. To further investigate persorption and molecular-scale porosity, data were taken from the binary and multiplex adsorption isotherm:CO2 preferential adsorption and hinder CH4, water adsorption properties of coal a greater impact than methane and carbon dioxide. Multiple gas adsorption, and the adsorption of CH4 |
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