Effect of flow rates of gases flowing through a coal bed during coal heating and cooling on concentrations of gases emitted and fire hazard assessment

Abstract

The flow velocity of gases in gobs directly influences the kinetics and intensity of gaseous components release during heating and cooling of coal. The assessment of fire hazard is performed on the basis of concentrations of particular gases in a mine air. These concentrations differ in coal heating and cooling phase which was proven in the study. This paper presented the results of the experimental study on temperature distribution in a simulated coal bed in heating (50-250°C) and cooling (250-35°C) phases as well as its correlation to variations in concentration of gases released in these phases and flow rates of gases flowing through the coal bed. The research was performed on twenty-two samples of bituminous coals acquired from various coal beds of Polish coal mines. Considerable differences were observed between heating and cooling phases in terms of the concentrations of gases taken into account in calculations of self-combustion index. In the heating phase temperature increase resulted in the decrease of concentrations ratios of ethane, ethylene, propane, propylene and acetylene, while in the cooling phase these ratios increased systemically. The effect of air (in heating phase) and nitrogen (in cooling phase) flow rate on the self-ignition index CO/CO 2 was also determined.

Prevention and Control of Spontaneous Combustion of Residual Coals in Acid‐Soaked Goaf in Gas Drainage Condition

“…In addition, they simulated the turbulent flow in the roadway, obtained the contour maps of airflow velocity and velocity vector diagrams, discussed areas prone to spontaneous combustion in the goaf, and optimized the ventilation system of the mine with coexisting disasters of gas and spontaneous coal combustion. Wang et al [24,25] developed a new type of composite material to control spontaneous coal combustion in coal mines. e material is a foam gel composed of composite foaming agent (CFA) and high-water absorbent gel (HWAG) and produced via physical and mechanical agitation.…”

Improved method of fire hazard assessment taking into account the effect of the primary temperature of a coal seam on the desorption ratio of gas indicators

“…In the attempts of the description of the oxidation process mechanism reported in the literature various parameters are applied in the development of kinetic models, covering coal sample weight loss, heat release, oxygen demand, as well as kinds and amounts of gaseous and solid products 14 . The effect of an air inflow to coal beds is also studied as one of the factors facilitating the development of fires in underground mines 15 , 16 .…”

Influence of Air Supply on Coal Spontaneous Combustion During Support Withdrawal in Fully Mechanized Coal Mining and its Prevention

“…The coal sample was found to have a maximum oxidation potential at an airflow velocity of 200 mL/min. Więckowski et al 20 showed that with the increase in the air flow, the ratio of CO/CO2 produced by the spontaneous combustion of coal samples increases with temperature and that the flow rate has an impact on the index value.…”