Thermal reactions of polyethylene with coal were studied. Coal used exhibited an endothermal effect in the temperature range
of 425-495C with a flat maximum (about 460C). In contrast, polyethylene alone was decomposed in the temperature range of
420-540C (mainly of 485-540C) with the significant DSC maximum at 510C. In the presence of coal this maximum shifted to
lower temperature (483C), therefore, coal promoted the decomposition of polyethylene. As decomposition of polyethylene yields
alkenes and alkadienes, the thermal reaction of polyethylene with coal under low temperature conditions can be described as
two-stage process in which the first stage includes the decomposition of polyethylene giving unsaturated hydrocarbons and
the second stage adsorption and hydrogenation of these products (mainly by coal hydrogen) on the inner surfaces of semicoke
In this research, thermogravimetry (TG/DTG) was used to determine the kinetic analysis of different coals and effect of cleaning process on kinetic parameters of raw and cleaned coal samples from Soma, Tuncbilek and Afsin Elbistan regions. Kinetic parameters of the samples were determined using Arrhenius and Coats and Redfern kinetic models and the results are discussed.
Authors:B. Avid, B. Purevsuren, M. Born, J. Dugarjav, Ya. Davaajav, and A. Tuvshinjargal
The coal sample of the Shivee Ovoo deposits has been non-isothermally pyrolysed in a thermogravimetric analyser to determine
the influence of temperature, heating rate and purge gas employed on the thermal degradation of the sample. The heating rates
investigated in the TG were 10–50 K min–1 to final temperature of 1000C. N2or CO2 were employed as well as type of purge gas on the process of thermal degradation of the coal sample. The coal was also investigated
in a fixed bed reactor to determine the influence of temperature and heating rate of the pyrolysis on the yield of products
and composition of the gases evolved. The main gases produced were H2, CH4, C2H2, C2H4, C2H6, C3H6 and C3H8 and also minor concentrations of other gases.
In this research, differential scanning calorimetry (DSC) was used to determine the combustion behavior and kinetic analysis
of raw and cleaned coal samples of different size fractions. DSC curves of the three coal samples (Soma, Tuncbilek and Afsin
Elbistan) showed two reaction regions. The first reaction region was due to moisture loss (endothermic) and observed in the
temperature range of ambient to 150C. The second region was the exothermic region due to the combustion and observed in the
temperature range of 150 to 600C. Kinetic parameters of the samples were determined using Roger and Morris kinetic model
and the results are discussed.
Authors:J. Liu, D. He, L. Xu, H. Yang, and Q. Wang
The combustion behavior of Shuangya Mountain (SYM) coal dust has been investigated by means of TG in this paper. The reaction fraction can be obtained from isothermal TG data. The regressions of g(), an integral function of
vs. t for different reaction mechanisms were performed. The mechanism of nucleation and nuclei growth is determined as the controlling step of the coal dust combustion reaction by the correlation coefficient of the regression, and the kinetic equation of the SYM coal dust combustion reaction has been established.
Authors:M. Kozlowski, R. Pietrzak, H. Wachowska, and J. Yperman
The influence of oxidation of coal, performed with different oxidising agents, on the sulphur species was studied. Conversions of the sulphur species were investigated by the Atmospheric Pressure-Temperature Programmed Reduction method (AP-TPR). The removal of pyrite proved to be advantageous for AP-TPR analysis. It was found that non-thiophene sulphur species undergo easier oxidation by different agent then thiophenic structures.
This research comprises the applicability of complex thermal analysis technique (TG/DTG, DTA) in the determination of calorific
values of coals of different origin. The calorific values, those obtained by thermal analysis are compared with an adiabatic
bomb calorimeter by the standard ASTM method, and the results are discussed.
Authors:V. Strezov, J. Lucas, T. Evans, and L. Strezov
The apparent specific heat of coal was measured by employing a computational calorimetric technique during continuous pyrolysis
at heating rates of 10, 25 and 100C min-1. For all of the examined heating rates, the apparent specific heat was found to be approximately 1.4 kJ kg-1 K-1 at room temperature. When the sample reached decomposition temperature (~410C), the specific heat increased to 1.9 kJ kg-1 K-1. From this point, the apparent specific heat was greatly influenced by the coal reaction mechanism. For this purpose a detailed
gas analysis was carried out for the three examined heating rates. It was found that with increased heating rates, the devolatilisation
reactions were shifted to higher temperatures, as reflected in the measured apparent specific heat.