A Chemical Reaction Model of the Self-Heating of Coal

In order to further understand the self-heating of coal, a chemical reaction model was proposed based on the previous model including two parallel reaction sequences. There are three different reaction sequences in this model. In comparison with the two parallel reaction sequences, the third reaction sequence is the self-reaction of initial active groups in coal. The reaction products of seven different ranks of coal samples were tested under inert atmosphere. The coal samples were particles ranging from 0.18 mm to 0.38 mm; the flow rate of nitrogen flowing into coal sample was 100 mL/min; the heating rate of reaction surrounding was 0.8 °C/min; the tests were carried out at temperatures starting from 30 °C and reaching 180 °C. The generation of the reaction products was analyzed every 10 °C rise of coal temperature from 30 °C. The results show all the coal samples tested generate CO, CO₂, CH₄ and C₂H₆ at low temperatures; only some special coal samples can generate C₂H₄ and C₃H₈ and their generation amount were small; no coal sample generate C₂H₂. Based on the analysis, it indicates the self reaction of initial active groups exists in the self-heating of coal at low temperatures. The model including three reaction sequences can present the self-heating of coal comprehensively.