The interactive effects of operating parameters on ash slagging during oxy-biomass combustion based on response surface methodology

Oxy-biomass combustion is one of the most promising carbon-negative technologies for achieving carbon neutrality, while ash slagging heavily hinders its application, which is affected by operating parameters significantly. In this study, the interactive effects of reaction temperature, O2 concentration, and recycled SO2 on the tendency of ash slagging were systematically explored by response surface methodology (RSM). The results showed that O2 concentration had the most important influence on the changes in ash softening temperature (ST), followed by reaction temperature and recycled SO2. Besides, there were strong interactions among these operating parameters, of which increasing O2 concentration dramatically amplified the effects of reaction temperature on ST. Meanwhile, O2 also had the dominant influence on the ash slagging index (RAFI), while it was dramatically weakened with increasing reaction temperature or SO2 concentration. Moreover, a novel method of ternary phase diagram was proposed for the simultaneous prediction of ST and RAFI, which revealed that the ash slagging tendency could be modified to the medium zone by adjusting reaction temperature, O2 concentration, and recycled SO2 to the ranges of 700 °C–730 °C, 40%–45%, 1500 ppm–1900 ppm, respectively.