Kinetics, thermodynamics, gas evolution and empirical optimization of cattle manure combustion in air and oxy-fuel atmospheres

Abstract

Thermogravimetric (TG) and TG-Fourier transform infrared (FTIR) analyses were performed to quantify the comparative performances of cattle manure combustion in air (N2/O2) and oxy-fuel (CO2/O2) atmospheres at four heating rates. Out of the distributed activation energy model, Flynn-Wall-Ozawa (FWO), Friedman and Starink methods (R2 ≥ 0.86), the FWO method on average led to the highest R2 value with the lowest activation energy. On average, the combustion in the oxy-fuel atmosphere had the lowest activation energy (180.6 kJ/mol) with the highest R2 value (0.9812). Our TG-FTIR results showed that CO2 was the major gas evolution of the cattle manure combustion. Interaction effects of atmosphere type by heating rate on the multiple responses of remaining mass, derivative TG, and differential scanning calorimetry were found to be significant (p < 0.001). The joint optimization of the three responses was achieved at 424.6 °C in the air atmosphere at the heating rate of 40 K/min.