CFD Simulation Study on Nitrogen Injection to Suppress Coal Spontaneous Combustion in Goaf under Downward-Ventilation Conditions.

Abstract

In the coal mining process, injecting nitrogen into the goaf is an effective method to suppress coal spontaneous combustion, which is widely adopted due to its significant inhibitory effect and low cost. Optimizing the injection volume and position of nitrogen is crucial for enhancing fire prevention and extinguishing efficiency and reducing safety risks. This study utilized CFD numerical simulation technology to investigate the spontaneous combustion risk in the goaf of the 81203 working face in Baode Coal Mine under the combined U + L ventilation and downwind ventilation conditions. The influence of different nitrogen injection positions and volumes on the distribution of the "three zones" related to coal spontaneous combustion in the goaf was analyzed. By simulating the changes in the oxygen and methane concentration fields in the goaf, this study proposed an optimized nitrogen injection strategy to improve fire prevention and extinguishing efficiency. The results show that setting a nitrogen injection port 90 m from the working face on the intake side of the 81203 auxiliary transport drift and injecting at a rate of 400m³/h meters per hour can achieve the best inhibitory effect and reduce costs.