Coke combustion rate data

The kinetic parameters for coke combustion were obtained by fitting to eq. (14) the experimental data of weight loss rate, dC/dt, obtained in thermogravimetric equipment by working under a programmed sequence of temperature-time [9]. 

The burning rate of chars at a pressure of 1 atm for petroleum coke and the different coal rank has been compared by Sergeant and Smith [27]. The collected experimental data show that the char burning rates expressed in (kg m- s ) is slightly lower for the same particle temperature, for petroleum coke against anthracite however the behavior of both coke residue (petroleum coke) and char (anthracite) is similar. The burning profile technique is a method for predicting the relative combustion characteristics of fuels. 

The values of the real systems, obtained from experiments at pressures up to 50 bar, may be extrapolated to still higher pressures since E = f(P) and log A = f(F) are continuous functions. The supply of oxygen in the oxidation experiments at 50 bar pressure is sufficient to ensure attainment of the asymptotic limits at least in the first reaction step (LTO). Evaluation of the second reaction step of the oxidation (fuel deposition) is more difficult because an increase of the heating rate provokes the occurrence of additional peaks, which will be flattened as a consequence of a rise of the pressure. For the consecutive and parallel oxidation and pyrolysis reactions in this step, overall values of E and log A have been found, which only give steady functions for the vacuum residue. The data of the last reaction step (fuel combustion) may be evaluated very easily. They also give steady functions for E = f(P) and log A = f(P). All substances tested behave similarly to activated carbon (charcoal). Only the coke residue of -hexylpyrene reacts completely differently and demonstrates different curves in the plots of the reaction rate constant and the half life time versus the pressure. In this reaction step the curves did not reach the asymptote even at pressures of 50 bar, but they may be extrapolated to higher pressures. 

Figure 6.5.16 Effective rate constant of gasification of blastfurnace coke with CO2 and combustion with O2 (fixed bed data from Table 6.5.2).

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