Influence of air amount on index gas for lignite combustion

Brown coal of Pingzhuang at Ruian was taken as the sample,the temperature range of the coal during combustion stage was determined by thermo gravimetric test,and the spontaneous combustion experiment was carried out by using tube furnace heating system.Gases were obtained at 40,80,120,160 and 200 m L/min of air volume respectively.In order to determine the correlation degree of the optimal index gas,the gray correlation method was used to analyze the gas.The results show that the temperature of the lignite combustion stage is247-433 ℃,and the rapid combustion state is achieved at about 408 ℃.When the air volume is constant,the correlation degree of temperature of CO_2/ΔO_2,CO/ΔO_2 and C_2H_4 is higher than that of CO,C_2H_6 and C_2H_4/C_2H_6.With the increase of air volume,the correlation between gas and temperature is: CO_2/ΔO_2 is the largest,followed by CO/ΔO_2,C_2H_4 and CO,C_2H_6 and C_2H_4/C_2H_6 are the smallest.So CO/ΔO_2,CO/ΔO_2 and C_2H_4 can be used as the main quota,CO is used to predict the coal mine closed fire zone combustion status.