Analysis of the Impact of Auxiliary Ventilation Equipment on the Distribution and Concentration of Methane in the Tailgate

Abstract

Methane, which is commonly found in hard coal deposits, represents a considerable threat to the safety of mining operations in these deposits. The paper presents the results of tests, aiming to limit the negative impact of methane on hard coal exploitation and improve work safety. The tests encompassed an analysis of methane concentration distributions in the tailgate (in the intersection area with the longwall), with account being taken of auxiliary ventilation equipment. This equipment is responsible for reducing methane concentration levels in the intersection area between the longwall and the tailgate. The analyses presented in the article were conducted for a spatial model of a longwall area, using the Computational Fluid Dynamics (CFD) method. Account was taken of the real-world measurements of the headings as well as the measurement data concerning methane concentration and ventilation parameters. The tests took into account methane emissions from the mined coal and from the goaf with caving. The analyses were performed for the system with and without auxiliary equipment, for different velocities of the additional air stream. This made it possible to compare both systems and determine the impact of auxiliary equipment on the distribution and concentration of methane in the most vulnerable area of exploitation. The distributions of the air and gas mixture were also determined in the analysed headings and goaf with caving. The results obtained clearly demonstrate that using auxiliary equipment has a significant effect on the ventilation parameters of the air stream and leads to reduction in methane concentrations in the most vulnerable section of the longwall. These results also confirmed the advantages of auxiliary ventilation equipment, which should contribute to their wider application in underground hard coal exploitation.