A thermal analysis study of the oxidation of brown coal chars

Abstract

The combustion of brown coal chars, obtained at different pyrolysis temperatures, have been investigated using TG, DTG and DTA thermal analysis methods. The burning profiles and the kinetic parameters derived from TG and DTA data show that all the chars are less reactive than the parent coal. The higher temperature chars have lower overall reactivity. From the corresponding infrared spectra, the chars obtained at 800"~ and I000 ~ appear to have graphitic structures.Victorian brown coal is a low rank, non-coking coal which produces a char during the pyrolysis process. Brown coal char is mainly used in the manufacture of acetylene for the plastics industry [1]. The properties of char depend on the conditions of pyrolysis via which it is produced.Thermal analysis offers an attractive and rapid method for the investigation of the char oxidation process. The DTA curve reflects the magnitude of the enthalpy change during combustion [5], and the TG and DTG profiles can be used to derive corresponding kinetic parameters [2][3][4][5][6][7][8][9][10].Several studies have been reported [2,4] on the reactivity of bituminous coal char using isothermal TG techniques. The results obtained by Khan [2] suggest that lowtemperature chars exhibit higher reactivity than the parent coal or hightemperature chars and that the oxygen chemisorption capacity is an important reactivity parameter. Patel et al. [7] studied the combustion rate of lignRe char by isothermal methcds. The activation energy obtained in the chemical rate controlled zone was 120 kJ/mol. Compared to isothermal analysis, non-isothermal analysis has some advantages [12]. One mass loss curve is equivalent to a large number of isothermal mass loss curves and only one sample is required. The kinetics of oxidation can be derived over the entire relevant temperature range.Victorian brown coal and char are highly reactive with oxygen. It is very difficult to use isothermal techniques to investigate the oxidation kinetics, because the John Wiley & Sons, Limited, Chichester Akad~miai Kiad6, Budapest

Intrinsic kinetics of CO2 gasification of a Victorian coal char

“…Studies on the thermal analysis of Victorian brown coal to determine pyrolysis and combustion kinetics can be found in the open literature [14][15][16][17][18][19]. However, very few studies reported provided information on the gasification kinetics of Victorian brown coals; those available were summarised by Bhattacharya et al [20].…”

Unusual Devonian Coal: A New Type of Jet

“…В целом характер полученного ИК-спектра идентичен таковым бурых углей (суббитуминозных лигнитов по европейской классификации) [Файзулина, 1967;Ma et al, 1989;Saikia et al, 2007].…”

Thermal analysis of Australian coals—A short review

“…Ma et al [15] have applied simultaneous TG-DTG/DTA techniques to derive kinetic parameters for the oxidation of a brown coal sample and a series of corresponding chars. The DTG burning profile of Loy Yang coal and a series of corresponding chars obtained at various temperatures are shown in Fig.…”