Search

Water-based fracturing fluid is a key component in coal bed methane (CBM) extraction, which is a promising way forward for the green extraction of methane. The adsorption by coal is highly affected by tiny particles in the fracturing fluid. Aiming at exploring the effect of mixing non-adsorbent particles into coal on the adsorption, an atmospheric pressure granulated coal adsorption system with a flow meter was designed to perform tests. During the experiments, the effect of coal particle size, coal mass, and addition of tiny granules on adsorption was analyzed. The obtained results show that the addition of iron powder reduces the adsorption capacity and average adsorption rate of granular coal, and makes the adsorption speed peak earlier. It is found that the change in the adsorption amount has a weak positive correlation with the coal particle size, and the change of the average adsorption rate has a weak positive correlation with the size. However, in the absence of iron powder, the average adsorption rate is negatively correlated with the coal size, and the effect of the coal mass on the average adsorption rate and adsorption capacity is very weak. In large granular coal, the adsorption capacity is independent of size. Under the experimental conditions, strong adsorption occurred between 500 and 1750 s, and the adsorption kinetic process showed a slow-fast-slow "S"- curved distribution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption properties of single-component gases; • Competitive adsorption properties of multi-component gases; • Effect of multi-component gases adsorption on methane adsorption. To further understand the competitive adsorption of multi-component gases in the goaf is critical for coal mine safety. However, the presence of combustible gases from coal spontaneous combustion further increase the complexity of competitive adsorption. To unravel this veil, a series of adsorption properties studies are carried out by molecular simulation. The results show that combustible gases have inhibitory effect on CH 4 adsorption to a certain extent. The isosteric heat of adsorption is not affected by other factors because of the initial stage of adsorption. This study can provide further insights into competitive adsorption in the goaf. [ABSTRACT FROM AUTHOR]

[Display omitted] • The internal moisture can evidently change the structural properties of anthracite. • A relatively increased internal moisture can reduce the adsorption property of CH 4. • The occurrence of moisture inside anthracite can hinder the diffusion of CH 4. To reveal the influence of internal moisture on CH 4 adsorption and diffusion is of great significance to the development of coalbed CH 4. Here, we use molecular simulation methods to explore the influence of internal moisture on the microporous morphology, adsorption property, and diffusion behavior. The results show that internal moisture can change the structural properties of coal, and the pore structure parameters reduce with increase of the internal moisture. Adsorption property indicators indicate an increased internal moisture can reduce the adsorption property. In addition, a negative correlation between the internal moisture and self- and transport diffusivities coefficient is revealed. [ABSTRACT FROM AUTHOR]