Study of resolution capability of pyrolysis characteristic index of low-rank bituminous coal

Abstract：Abstract： A quantitative parameter, named pyrolysis characteristic index （P）, was defined based on thermogravimetric analysis （TGA） with the aim to evaluate coal pyrolysis activity of bituminous coal. Pyrolysis of Jixian gas coal and Dongrong long flame coal at heating rates of 5, 15 and 30 ℃/rain was conducted with thermogravimetric analyser, then the TGA data were analyzed and evaluated by index P and other commonly used indices or methods as well. The results show that TG, DTG and maximum mass loss Wm~x are unable to reflect the pyrolysis be- havior in a reasonable regularity and tendency of coals with different metamorphism or at heat- ing rates, which confirm that TG, DTG and Wmax are not necessary suitable to be used in evalu- ating the influence of coal type and hating rate on pyrolysis activity. The maximum reaction rate （dW/dt）max or volatile releasing characteristics index R of Jixian gas coal is larger than Dongrong long flame coal when the hating rate is 30℃/rain, which is in contradiction with basic theory of coal chemistry, which suggest that neither （dW/dt）max nor volatile releasingrcharacteristics index R is accurate to compare pyrolysis activity, between dllterent coal types. Meanwhile, P increases obviously with the increase of heating rate, and the P of Dongrong long flame coal is larger than Jixian gas coal at different heating rates. Therefore, itrs accurate and quantitative to reveal the impact of coal type and hating rate on pyrolysis activity by the newly established index P, which suggest P be used to evaluate low-rank bituminous coal＇s py- rolysis activity during the whole pyrolysis process.