Co-combustion of water hyacinth (Eichhornia crassipes) and coal: thermal behavior and kinetics analysis under the Coats-Redfern method

Abstract

The combustion of solid fuels is the thermal decomposition of the organic matter in the presence of sufficient oxygen to generate heat, generally comprising the volatile burning initially then followed by char combustion. In this work, the synergistic effect between the water hyacinth (WH) and coal and their kinetics during co-combustion were studied by thermogravimetric analysis. The blended fuel was comprised of the parent sample of WH and coal in the mass ratio of 60:40. The parent fuels of WH and coal were also evaluated as the control sets. The sample’s combustion behaviors were investigated through the apparatus of a thermogravimetric analyzer under a heating program of 40 °C/min. During the combustion process, from room temperature up to 1000 °C, the flow rate of 100 ml/min of air atmosphere was continuously maintained to ensure the occurrence of the combustion process. Results pointed out that the synergistic interaction in the blended fuel improved the combustion, where the initial temperature of decomposition was forced toward the lesser value, and the mass loss rate was promoted to the higher one compared to the parent coal. The kinetics evaluation using the fitting model of Coats-Redfern revealed that the WH in the mixture brought about the activation energy headed for a lower value, with the respective of coal, blended fuel, and WH were 100.08, 77.39, and 63.10 kJ/mol. These results confirmed that WH in the blended fuel considerably influenced their thermal behavior and kinetics during the combustion.