Study on the suppressive effects of carbon dioxide on coal dust explosions: Experimental and simulation discussion

Abstract

This study systematically investigates the effectiveness and mechanism of CO₂ in suppressing coal powder explosions from both macroscopic and microscopic perspectives. Experimental and kinetic modeling results reveal that the explosion pressure of coal powder decreases with increasing CO₂ volume fraction, with an effective suppression concentration of 15 %. CO₂ enhances the thermal stability of coal powder, raising the activation energy of the combustion stage from 72.577 kJ/mol to 76.541 kJ/mol. In addition, the microstructure and predominant forms of the solid explosion products show that CO₂ effectively suppresses the breakage of carbon chain structures and the release of CH₄ and other gases during coal powder explosions. It also significantly suppresses the formation of C-O and hydroxyl-π functional groups, with their relative contents decreasing by 28.29 % and 10.43 %, respectively. This is consistent with the numerical simulation results, which show a decrease of 0.048 mole/cm³·s in the total OH production rate, clearly identifying the key step in the chain reaction blocked by CO₂: H + O₂ → OH + O. This establishes the suppression mechanism of CO₂ on coal powder explosions.