Study on optimization of preparation and liquid content of thermo-responsive inhibitor for preventing coal spontaneous combustion

Abstract

To address the issue of fast failure of salt inhibiting liquid in preventing coal spontaneous combustion, our team proposed the use of a thermo-responsive secundina sphere inhibitor (TRSSI). This agent involved wrapping the salt inhibiting liquid with phase change materials (PCMs). The previous experimental results were proven. However, subsequent observations revealed surface cracks in the TRSSI upon room temperature cooling, leading to internal liquid leakage and a low rate of complete formation. To address this, this paper conducted a thermal analysis of the TRSSI preparation process. Through range analysis, three factors affecting the thickness of the shell were determined: notably, the ice-ball radius exhibited a significant positive correlation, while the initial temperature of the PA-SA had a substantial negative impact. Conversely, the initial temperature of the ice-ball showed relatively minimal influence on thickness. By combining the regression analysis equation and mechanical conditions, the optimal volume ratio, ice-ball radius, and shell thickness under varying compressive strengths were obtained. Water retention tests showed that the TRSSI exhibited a mere 3.67% water loss rate over nine months at room temperature. The adiabatic heating test of coal demonstrated that the TRSSI, when applied to coal seam surface, accurately targeted the heat source center and swiftly reduced its temperature. Ineffective TRSSIs absorbed heat, stacked on each other, and formed a tight water-retaining layer on coal seam surface, effectively prolonging the coal’s self-heating oxidation period.