The role of methane buoyancy on the stability of airway airflow in underground coal mine ventilation

Abstract Coal mine ventilation is an extremely complicated system that can be disturbed by several factors. This paper addresses the fact that the stabilization of airflow in the airways can be induced by methane buoyancy. The formation and characteristics of methane buoyancy are further elaborated and combined with the airflow stagnation accident that occurred in the Tangshan coal mine in China. Field tests and experimental studies were conducted to verify the role of methane buoyancy on the stability of airway airflow. The results indicate that methane buoyancy is generated in inclined airways with gas accumulation, which can be regarded as an increment of buoyancy. Methane buoyancy can induce airflow stagnation or airflow reversals, especially in airways with relatively low airflow velocity. To maintain the stability of the airflow, in those airways with gas emissions, a higher airflow rate and velocity should be ensured, and large airways inclination should be voided.