Synergistic effect, kinetics, and pollutant emission characteristics of co-combustion of polymer-containing oily sludge and cornstalk using TGA and fixed-bed reactor

The synergistic effect of co-combustion of polymer-containing oily sludge (POS) and cornstalk (CS) was investigated by thermogravimetric analyzer (TGA) and fixed-bed reactor. The TGA results show that the co-combustion process of POS-CS can be divided into three stages: the evaporation of the oil-water, combustion of volatiles and light oil, and the coupled combustion of heavy oil, fixed carbon, and organic matter. With CS ratios from 30% to 70%, the ignition index and comprehensive combustion index of POS increase by 1.18–2.33 times and 1.53 to 3.95 times, respectively. The POS-CS blends have an inhibitory effect in the temperature range of 180–260 °C and 420–495 °C, however, a synergistic effect is exhibited throughout the entire temperature range. The activation energies of the blends are 33%, 45%, 41%, 35% and 53% lower than that of POS, at the CS ratios of 30%, 40%, 50%, 60% and 70%, respectively. The fixed-bed experiments indicate that the emissions of NO and SO2 decrease with the increase of CS. Specifically, the NO and SO2 emissions of the blend with CS ratio of 70% are 2.86 mg g−1 and 3.49 mg g−1, which decrease by 31.6% and 37.8%, compared with POS, respectively. In addition, the pollutant level (NO and SO2) of POS-CS blends is also lower than some typical solid fuels.