Oxy-fuel and air combustion performances and gas-to-ash products of aboveground and belowground biomass of Sedum alfredii Hance

Abstract

The eco-friendly disposal choices of phytoremediation biomass still remain to be explored. This study characterized the combustions of Sedum alfredii Hance (SAH) in response to its aboveground (SAH-A) and belowground (SAH-B) parts, the oxy-fuel (CO2/O2) and air (N2/O2) atmospheres, temperature, and heating rate. The decomposition behaviors, gas-to-ash characteristics, thermo-kinetic parameters, and mineral transformations were quantified. In both atmospheres, the combustion performances were better for SAH-A than SAH-B at the same heating rate. In the range of 400.0–598.8 °C, the maximum mass loss rate of both samples obviously decreased and delayed with CO2 replacing N2 at the same oxygen concentration. The SAH-A and SAH-B combustions in both atmospheres emitted C- (CO2, CO, CH4, and small molecular organic substances) and N-containing (HCN and NH3) gases. In both atmospheres, the temperature dependency of the gas emissions remained the same. Both empirical indices and ternary phase diagrams indicated that both samples had a high deposition risk. Thermochemical equilibrium simulations were used to predict the slagging risk in response to ash mineral transformations. Our findings can provide new insights into the combustion dynamics of phytoremediation biomass and its effect on CO2 capture, utilization, and storage in mitigating climate change.