Thermal characteristics and kinetic analysis of coal-oxygen reaction under the condition of inert gas

ABSTRACT

To ascertain fire prevention and extinguishing mechanism of inert gas in coal mine goaf, TG-DTG-DSC experiments of coal-oxygen reaction at 30–850℃ under N₂ and CO₂ conditions were carried out, and the thermal characteristics and kinetic factors were analyzed. The process of coal-oxygen reaction was divided into five stages by the four characteristic temperatures of T₁ (temperature at which water evaporates completely), T₂ (temperature at which coal begins to decompose intensely), T₃ (ignition temperature) and T₄ (burnout temperature). With the decrease of O₂ concentration, T₂, T₃, and T₄ increased, the total mass loss and heat release decreased, and the decomposition degree increased. The injection of N₂ and CO₂ reduced the apparent activation energy and pre-exponential factor of T₁–T₂, T₂–T₃ and T₃–T₄ stages, and there was dynamic compensation effect between activation energy and pre-exponential factor. Under the same O₂ concentration conditions, the effect of CO₂ was more significant than that of N₂. Reducing oxygen concentration by injecting N₂ and CO₂ could rapidly reduce the degree of coal-oxygen reaction rate. This study is of great significance for the prediction of coal spontaneous combustion and the using of N₂ and CO₂ coal fire prevention and extinguishing technology.

KEYWORDS:

• Coal mine goaf fire
• inert gas
• TG-DTG-DSC experiments
• thermal characteristics
• kinetic analysis

Ethics

This article does not present research with ethical considerations.

Authors’ Contributions

Fei Wang conceived of the study, designed the study, coordinated the study and helped draft the manuscript; Hongwei Liu carried out the experiment, participated in data analysis, participated in the design of the study and drafted the manuscript. All authors gave final approval for publication.

Competing Interests

The authors declare no conflict of interest.

Additional information

Funding

This work was supported by Key Research and Development (R&D) Projects of Shanxi Province (No. 201803D31053); Major Technological Research Projects of Shanxi Coking Coal Group Co., LTD. (No. 201812xs06); National Natural Science Foundation of China (No. 51804212); High-end Foreign Experts’ Intelligence Introduction Project of the State Administration of Foreign Affairs (GDW20181400424); Opening Projectof State Key Laboratory of Explosion Science and Technology (Beijing Instituteof Technology) (No. KFJJ19-03M).