Study on the co-combustion behavior of rice straw with coal gangue and fixation of alkali metals and ash melting characteristics

Abstract

Abstract Because it is clean, low carbon, and renewable, biomass offers the greatest practical value. Nevertheless, during combustion, issues like slagging, agglomeration, and corrosion can occur due to the high concentration of Cl and alkali metals (K and Na), which lowers combustion efficiency. On the other hand, gangue (CG), when combined with biomass as an additive, can successfully prevent slagging during the burning process. However, more research is needed to determine how CG affects the properties of ash melting, alkali metal immobilization, and biomass combustion behavior. Thus, the impacts of CG on the co-combustion behavior, fugitive forms of alkali metals, and ash melting properties of rice straw (RS) were examined in this article. X-ray diffraction analysis, scanning electron microscopy, thermogravimetric-differential thermal analysis, ash melting temperature test, and tube furnace combustion studies were among the experimental techniques utilized to characterize the ash. The findings demonstrated that adding CG to biomass might enhance both the overall combustion performance and the flammability index, with notable synergistic effects connected to the ratio of biomass to CG. Alkali metals in the ash could be efficiently fixed by CG, and it was found that adding 20% of CG to the biomass had the best results. The degree of ash melt slagging was successfully reduced and controlled with a rise in the CG addition ratio, and silica-aluminate with a higher melting point and stable nature was produced, which could effectively raise the biomass's ash melting temperature.