Analysis of Coal Spontaneous Combustion by Thermodynamic Methods

ABSTRACT

In order to better determine the spontaneous combustion tendency of coal, two types of heating rate methods, namely, single and multi-scan methods, commonly used in the field of spontaneous coal combustion are summarized based on a thermal analysis kinetics method. The single scanning rate method mainly included the Coats–Redfern, Achar, universal equation, MacCallum–Tanner, Madhusudanan–Krishnan–Ninan, and non-isothermal thermogravimetric and differential scanning calorimetric methods. The multi-scan rate method mainly included the Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Starink, and Friedman methods. For each of these methods, their respective theoretical basis, advantages, and disadvantages were described. In addition, the Popesc and Malek methods were used to determine the optimal reaction kinetic model. In view of the compensation effect, the invariable activation energy E_inv and the pre-exponential factor lnA_inv at different heating rates were determined. For each method, the oxygen weight gain stage of Shaanxi bituminous coal was selected as an example interpretation.

KEYWORDS:

• Coal spontaneous combustion
• compensation effect
• multiple scan rate method
• single scan rate method
• thermal analysis

Additional information

Funding

This work was supported partly by the “Tianjin Science and Technology Plan Major Special Project (Grant No.18ZXAQSF00020)”, partly by the “Tianjin Science and Technology Plan Key R&D Program (Grant No.18YFJLCG00140)”, partly by “the general project of Tianjin Natural Science Founds (Grant No. 19JCYBJC23000)”, partly by “131 Innovative Talents Cultivation Engineering for Tianjin Province, China” and partly by “Training Program for Innovative Research Team in Tianjin Institutions of Higher Education” (Grant No.TD13-5021).