Determination of the Kinetic Parameters of Oxy-Fuel Combustion of Coal With a High Ash Content

Abstract

-The aim of this study was to determine the kinetic parameters of the oxy-fuel combustion of char from a Brazilian bituminous coal with a high ash content. The char, with a particle diameter of 715 μm, was prepared in a N 2 atmosphere at 1173 K. The oxy-fuel combustion assays were performed using a thermobalance at different temperatures and O 2 /CO 2 gas mixtures of different concentrations. According to the unreacted core model, the process is determined by chemical reaction at low temperatures, with an activation energy of 56.7 kJ.kmol -1 , a reaction order of 0.5 at 973 K and a reaction order of 0.7 overall. The use of the continuous reaction model did not provide a good fit for the experimental data because the consumption of the particles during the reaction was not constant, as predicted by the model. According to the Langmuir-Hinshelwood model, the activation energy for the first step was 37.3 kJ.kmol -1 .

Kinetics of the Oxy-fuel Combustion of High-Ash-Content Coal from the Candiota Mine, Rio Grande do Sul

“…The temperature of the oxy-fuel combustion was limited to 1173 K because the mixed control reaction predominates at approx- imately 1273 K, as has already been observed by Pohlmann et al 9 and Nunes and Marci ́lio. 21 3.3. Influence of the O 2 Content in the Gas Mixture.…”

“…Aproximately 150 g of coal was placed in a stainless-steel reactor, as described by Nunes and Marci ́lio. 21 The sample remained for 60 min at a predetermined temperature. On the basis of these results, the particle sizes were selected for the oxy-fuel combustion reactions.…”

“…For comparison purposes, Table 1 also presents the results of the characterization of the sub-bituminous Brazilian Leaõ coal, obtained by Nunes and Marci ́lio. 21 2.2. Oxy-fuel Combustion.…”

Demineralization of Brazilian Coals for Use in Gasification and Oxy-Fuel Combustion Processes, Aiming to Reduce CO2 Emissions

“…Effect of Temperature. The temperatures used for the oxy-fuel combustion reaction in this work were 873, 973, 1073, and 1173 K. These temperatures were previously selected based on thermogravimetric testing with ROM samples, according to Nunes and Marcilio 59 and Nunes et al, 53 so that we could compare the results obtained with demineralized and ROM samples using the same temperatures and O 2 concentrations in CO 2 .…”

“…Kinetics Parameters for the Oxy-Fuel Combustion Reaction of ROM and Demineralized Samples of Candiota Char Nunes et al 60 b Nunes and Marcilio 59. …”