Beypazari lignite was investigated by differential scanning calorimetry (DSC), thermogravimetry (TG), high pressure thermogravimetry
(HPTG) and combustion cell experiments. All the experiments were conducted at non-isothermal heating conditions with a heating
rate of 10°C min−1, in the temperature range of 20–700°C. DSC-TG data were analysed using an Arrhenius-type reaction model assuming a first-order
reaction. For the HPTG data the Coats and Redfern equation was used for kinetic analysis. In the combustion cell experiments
the Fassihi and Brigham approach was used in order to calculate kinetic data. Finally a comparison is made between the kinetic
In this study, combustion curves of twenty-five Turkish lignites were obtained through use of a differential thermal analyser.
20 mg lignite samples were heated at a constant rate of 10 deg·min−1 in a 40 cc/min flow of air up to 1073 K and held for 10 minutes at this constant temperature. The combustion curves of the
samples are compared and discussed.
In this study, thermal
characteristics and kinetic parameters of cleaned Tunçbilek lignite
were determined by using a Setaram Labsys DTA/TG/DSC thermal analysis system
both for combustion and pyrolysis reactions. Experiments were performed at
a heating rate of 10°C min–1 under reactive
(air) and inert (nitrogen) gases up to 1000°C. Non-isothermal heating
conditions were applied and reaction intervals were determined for combustion
and pyrolysis reactions from obtained curves. The combustion properties were
evaluation by considering the burning profile of the lignite sample. Burning
temperatures and rate of combustion were determined from TG/DTG curves. Calorific
value of the lignite sample was measured by DSC curve and compared with the
adiabatic bomb calorimeter result.
In this research, combustion curves of seventeen lignite samples from the Thrace basin (Turkey) were analysed using thermal
analysis (TG/DTG) techniques. A comparative analysis was performed considering the relationship between peak temperature,
burn-out temperature, moisture content, ash, volatile matter, fixed carbon and calorific values of the samples studied and
the results are discussed.
In this study, the relationship between particle size and pyrolysis characteristics of Elbistan lignite was examined by using
the thermogravimetric (TG/DTG) and differential thermal analysis (DTA) techniques. Lignite samples were separated into different
size fractions. Experiments were conducted at non-isothermal conditions with a heating rate of 10°C min−1 under nitrogen atmosphere up to 900°C. Pyrolysis regions, maximum pyrolysis rates and characteristic peak temperatures were
determined from TG/DTG curves. Thermogravimetric data were analyzed by a reaction rate model assuming first-order kinetics.
Apparent activation energy (E) and Arrhenius constant (Ar) of pyrolysis reaction of each particle size fraction were evaluated by applying Arrhenius kinetic model. The apparent activation
energies in the essential pyrolysis region were calculated as 27.36 and 28.81 kJ mol−1 for the largest (−2360+2000 μm) and finest (−38 μm) particle sizes, respectively.
In this study, combustion curves of twenty-five original and demineralized Turkish lignite samples were obtained through use of a differential thermal analyser. The lignite samples were demineralized by treatment with hydrochloric and hydrofluoric acids. Samples of 20 mg were heated up to 1074 K at a constant rate of 10 K min−1 in a 40 cm3 min−1 flow of dry air. The rates of heat release from the original and demineralized samples were compared and are discussed.
This research presents the combustion behavior of lignite under different reaction pressures. Lignite from Alpagut, Çorum
of Turkey was combusted in its run off mine (ROM) condition under three different pressure levels of 172, 345, 517 kPa (25,
50, 75 psi). Experiments were done in a fully controlled temperature regime in an isolated combustion tube that operated in
coordination with a continuous gas analyzer. Combustion behavior of lignite under different pressures was characterized by
effluent gas analysis method. The changes in the amounts of consumed oxygen, evolved carbon oxides as well as variations in
the temperature were assessed. The combustion efficiency and effectiveness of lignite was evaluated in terms of thermal features,
from the viewpoint of reaction kinetics and by the computation of instantaneous fuel consumption at critical points. It was
seen that combustion of lignite tended to turn from a steady profile to a considerably rapid one with increase in pressure,
proving to be highly sensitive to the applied pressure level. Also, different levels of pressure resulted in distinctive combustion
behavior not only from the view of thermal characteristics, but also in terms of reaction kinetics.
In this research, the relationship between particle size and combustion kinetics and combustion properties of lignite samples
was examined by utilizing the thermogravimetric (TG/DTG) and differential thermal analysis (DTA) techniques. The lignite samples
separated into different size fractions were subjected to non-isothermal thermogravimetric analysis between ambient and 900�C
in the presence of 50 mL min−1 air flow rate. Activation energy (E) and Arrhenius constant (Ar) of combustion reaction of each size was evaluated by applying Arrhenius kinetic model to the resulting data. Combustion
properties of the samples were interpreted by careful examination of the curves. The apparent activation energies in major
combustion region were calculated as 41.03 and 53.11 kJ mol−1 for the largest size (−2360+2000 μm) and the finest size (−38 μm), respectively.
Thermal analysis increasingly being used to obtain kinetic data relating to sample decomposition. This work involves a comparative study of several methods used to analyse DSC and TG/DTG data obtained on the oxidation of Beypazari lignite. A general computer program was developed and the methods are compared with regard to their accuracy and the ease of interpretation of the kinetics of thermal decomposition. For this study, the ratio method was regarded as the preferred method, because it permits the estimation of reaction order, activation energy and Arrhenius constant simultaneously from a single experiment.