TG–FTIR analysis of oxidation kinetics of some solid fuels under oxy-fuel conditions

An Investigation Into the Characteristics and Kinetics of Oil Shale Oxy-Fuel Combustion by Thermogravimetric Analysis

“…Xie et al [13] observed an obvious delay in the decomposition of mineral carbonates in Huadian oil shale in CO 2 -based atmospheres when the temperature was above 700 °C. Estonian oil shale undergoes two reaction steps in oxy-fuel conditions above 650 °C, the first in the 650-890 °C range and the second between 890 and 960 °C [9][10][11]. Furthermore, Yörük et al [10] reported that the decomposition temperatures of MgCO 3 and CaCO 3 in CO 2 were different and the processes proceeded with maximum rates at 750 °C and 920 °C, respectively.…”

“…If α is 0.1 or 0.9, especially in oxy-fuel combustion, the lower R 2 value indicates that the reaction is unstable during the initial and end periods of oil shale combustion. The decrease of activation energy in the initial period of combustion reveals that at this stage the process is rather complex and proceeds slowly [9]. After exceeding the threshold energy, the product changes into a reactant and combusts, after which the whole process proceeds more rapidly [12].…”

“…This is because the special property of CO 2 is that it has a higher specific heat and lower thermal diffusivity compared to those of N 2 and the mass transport of O 2 to and through the reacting particles changes owing to the differences in its mass diffusivity between CO 2 and N 2 [3]. Thus, the combustion and kinetic characteristics of solid fuels in oxy-fuel combustion are of interest in fuel research [3][4][5][6][7][8][9][10][11].…”

“…Jabber and Probert [8] reported that there was a slightly greater mass loss during the devolatilization of Jordanian oil shale in CO 2 than in N 2 , and that the CO 2 -char reaction was more likely to occur at high temperatures. Meriste et al [9] compared the oxidation kinetics of oil shale and coal in 79% Ar/21% O 2 and 70% CO 2 /30% O 2 . Yörük et al [10] showed that the pyrolysis behavior of Estonian oil shale was very similar in Ar and CO 2 during water evaporation and organic matter decomposition, and the rate constants for char oxidation in O 2 /CO 2 were approximately 1.2-1.3times higher than those in the O 2 /Ar atmosphere.…”

Diffusional effects on differences of coal char reactivity between air and oxy-fuel combustion in thermogravimetric experiments

“…Rathnam et al [15] reported that no significant differences could be observed between O 2 /N 2 and O 2 /CO 2 cases with O 2 concentration C5 % in non-isothermal TG experiments, while the case of 2 % O 2 /98 % CO 2 exhibited an obvious increase in reactivity at high temperature. TG tests conducted by Meriste et al [16] revealed that there were no remarkable differences in the characteristic temperatures at oxidation of coal samples investigated in oxy-fuel and O 2 / Ar (modeling air) atmospheres. However, Li et al [17] found out that the burning process of pulverized coal in O 2 / CO 2 environment was delayed compared with that in air at the same oxygen content.…”