An Impact of Mechanical Stress in Coal Briquettes on Sorption of Carbon Dioxide

Abstract

The presence of gases (methane or carbon dioxide) in hard coal is connected with numerous threats for miners employed in underground mining facilities. When analyzing the coal-methane system, it is necessary to determine the relationship between pressure and gas sorption. Such a relationship should be determined under conditions similar to the natural ones – when it comes to both temperature and pressure. The present paper discusses the results of research conducted with the use of coal briquettes under the state of mechanical stress. Carbon dioxide sorption isotherms were determined for different values of stress affecting the coal material. For five coal samples collected in different mines of the Upper Silesian Coal Basin, Langmuir’s sorption isotherms were determined. The results point to significant impact that mechanical stress has upon the sorption process. It is about 1 percent of the value obtained for coal not subjected to stress per 1 MPa. The research results can also prove useful when analyzing hard coal seams from the perspective of their carbon dioxide sequestration abilities.

Methane Emission during Gas and Rock Outburst on the Basis of the Unipore Model

“…Further down, it slightly decreased and then its value remained constant ( Figure 1). Such considerable pressure gradients contained in the rock pore space generate gas stresses [10], which stretch the rock [11][12][13][14]. This phenomenon is connected with the development of crack networks due to exploitation stress, which affect the permeability of the excavation to methane [15].…”

The Influence of Temperature on the Expansion of a Hard Coal-Gas System

“…Moisture content was determined in accordance with the PN-80/G-04511 standard and ash content in accordance with the PN-80/G-04512 standard. Hard coal can be very heterogenous with respect to chemical and petrographic composition, even over short distances (<1 km) [23,24]. The use of a relatively large, solid sample, with a mass of approximately 20 g, allows for better representation of the coal bed being studied, compared to literature data, where, very often, small samples, often not exceeding 1 g, are used.…”

Development of temperature-induced strains in coal–CH4 and coal–CO2 systems

“…One of the effects is the swelling of coal. In situ, it results in stress and strain variations in a coal bed under overburden pressure (Skoczylas and Wierzbicki, 2014; Wierzbicki, 2017). Studies show that sorption-induced swelling of hard coal is an anisotropic process (Ceglarska-Stefańska and Czapliński, 1993; Ceglarska-Stefanska and Zarebska, 2002; Cui et al., 2007; Czerw, 2011; Espinoza et al., 2013; Karacan, 2007; Perera et al., 2011; Robertson and Christiansen, 2005; St.…”