Numerical simulation of carbonaceous raw material combustion in a coal seam channel

Purpose. The research aims to investigate the combustion behavior of carbonaceous raw materials, specifically pulverized coal, in a cylindrical channel within a coal seam. The research focuses on understanding the temperature field dynamics, the distribution of combustion products, and the stabilization of the combustion process over time. Methods. The research uses advanced Computational Fluid Dynamics (CFD) modeling using non-premixed combustion and the k-epsilon turbulence model. A cylindrical channel with a length of 30 m and a diameter of 1 m is selected, reflecting optimal conditions for co-gasification based on previous studies. Heat transfer processes are incorporated by activating the energy equation, accounting for heat generation from chemical reactions and its transfer via convection, conduction, and radiation. These considerations accurately represent the thermal and flow dynamics in the confined geometry. Findings. The simulation indicates the temperature field stabilization, with a peak of 1540°C achieved in the combustion zone after 24 hours, gradually decreasing to approximately 520°C further downstream. Oxidation reactions are most active within the first 6 m of the channel, producing CO2 as the primary combustion product. The flow velocity analysis indicates intense turbulence near the inlet, enabling efficient mixing of fuel and oxidizer. As the process progresses, turbulence intensity decreases, maintaining a steady distribution of thermal energy and stable downstream flow behavior. Originality. The research has resulted in the development of a comprehensive methodology for modeling pulverized coal combustion process in geometrically constrained coal seam channels, representing the staged progression of the process (early, mid, and final stages). Patterns of temperature field stabilization and the distribution of chemical species along the channel have been identified. Practical implications. TThe findings provide a foundation for optimizing underground coal combustion and co-gasification processes to improve geo-reactor systems’ efficiency.