Aluminium dust explosion suppression by KHCO₃ and K₂CO₃: The influence of the inhibitor's particle size and thermochemical synergy

This study investigated the effects of potassium carbonate salts (KHCO₃ and K₂CO₃) on the suppression of aluminium dust explosions. The inhibitor variables mainly include the particle size, the inerting ratio, and the mixing strategy. Experiments in a 20 L spherical explosion system revealed that the maximum explosion pressure (P_max) decreased significantly with increasing inerting ratios or with decreasing inhibitor particle sizes. Adding KHCO₃ reduced P_max more effectively than adding K₂CO_3, which achieved near extinction at 70 wt%. Compared with KHCO₃, a 7:3 KHCO₃/K₂CO₃ mixture at 60 wt% lowered P_max by 23 %. Thermal characteristic analyses, explosion residue analyses, and numerical modelling analyses indicated that the two inhibitors had different methods for reducing the aluminium explosion pressure. KHCO₃ primarily acted in the early stage of the aluminium explosion, whereas K₂CO₃ chemically participated in oxygen radical competition. The synergistic effects of the two inhibitor mixtures were clarified. These findings highlight the critical role of optimising the particle size, inerting ratios, and hybrid formulations to maximise the suppression efficiency and economic viability.