Investigation of the Usability of Modular Smart Nitrogen Kits in Combating Spontaneous Combustion in Underground Coal Mines Using CFD Analysis

Creative Commons License

Aksoy C. O., Uyar Aksoy G. G., Sarısan H. B., Özacar V., Yaman H. E.

PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, cilt.1, ss.1-61, 2026 (SCI-Expanded, Scopus)

Özet

Spontaneous combustion remains one of the most persistent safety hazards in underground coal mines despite extensive research on nitrogen inertization and Computational Fluid Dynamics (CFD)-based optimization of conventional centralized nitrogen injection systems. Existing approaches predominantly rely on permanent pipeline networks, continuous nitrogen supply, and fixed injection locations, which often result in inefficient nitrogen utilization under heterogeneous gob conditions. This study addresses this research gap by developing and evaluating a laboratory-validated Modular Smart Nitrogen Kit (MSNK), a decentralized and demand-based inertization technology designed to provide localized nitrogen delivery directly to combustion-prone regions.
A three-dimensional transient CFD model was developed for a representative longwall panel in the Soma Coal Basin (Türkiye). The gob was represented as a heterogeneous multilayer porous medium with spatially varying permeability and porosity. The operating characteristics of the laboratory-developed MSNK prototype were directly incorporated into the numerical model, establishing a direct link between engineering prototype development and CFD-based performance assessment. Three alternative MSNK deployment strategies were investigated under identical ventilation, boundary, and numerical conditions to evaluate oxygen depletion, nitrogen dispersion, combustion-gas suppression, methane behaviour, and thermal mitigation.
The simulations demonstrated that nitrogen transport is strongly controlled by the interaction between ventilation-induced airflow and heterogeneous gob permeability. All investigated deployment strategies successfully reduced oxygen concentration, suppressed combustion gases, and mitigated thermal accumulation. However, inertization efficiency was highly dependent on MSNK placement. The outlet-side deployment strategy consistently achieved the greatest oxygen depletion, the highest nitrogen accumulation, the most effective suppression of carbon monoxide and carbon dioxide, and the largest temperature reduction, whereas the distributed mid-gob configuration provided the most spatially uniform inertization.
The principal contribution of this study is the introduction and numerical evaluation of a prototype-based decentralized inertization concept that extends current research beyond the optimization of conventional centralized nitrogen injection systems. By integrating laboratory prototype validation with transient CFD modelling, the proposed framework provides a practical methodology for assessing localized inertization technologies and demonstrates the potential of modular nitrogen delivery to improve nitrogen utilization efficiency, operational flexibility, and fire prevention in underground coal mines.