Chain hydrocarbons formation law of different metamorphic grade coals at combustion phase

In order to study the gas formation components generated from different coals and the variation characteris- tics in a closed fire zone,the lignite of Pingzhuang Coal Mine,the gas coal of Wangying Coal Mine,the coking coal of Zhuxianzhuang Coal Mine and the lean coal of Mapu Coal Mine were selected as experimental coal samples. The tem- perature range of coals at the combustion phase were determined by thermogravimetric experiment. Using a self-made temperature programmed system,the combustion experiments on four kinds of coals were conducted in a tube furnace. The change laws of volume fractions,the initial temperature of chain hydrocarbons and oxygen concentration were ana- lyzed. The results show that the temperature range of lignite at the combustion phase is 247-433 ℃ ,the temperature range of gas coal at the combustion phase is 279-542 ℃ ,the temperature range of coking coal at the combustion phase is 313-574 ℃ ,and the temperature range of lean coal at the combustion phase is 333-618 ℃ . With the increase of metamorphic grade,the volume fractions of chain hydrocarbons decrease,the oxygen consumption increases. After the coal mine fire occurs and the fire zone is closed,the factors of the metamorphic grade and the formation amount of chain hydrocarbons can be comprehensively considered,the variation of chain hydrocarbons and temperature can be used to determine the fire zone development trend and lay a good foundation for fire prevention and extinguishment.