Correlations of chemical properties of high-alkali solid fuels: A comparative study between Zhundong coal and biomass

The utilization of Zhundong coal has given rise to serious ash-related issues mainly because of its high-alkali characteristic, partly similar to biomass with high-potassium content. The chemical properties of such coals and biomass may have marked impacts on reactivity and ash fouling. However, the correlations of different chemical properties of high-alkali solid fuels have been seldom investigated, and then only on a few samples. Here, a comparative study of chemical properties of Zhundong coal and biomass was conducted based on a large database. Correlations between carbon content and ash yield and carbon content and fixed carbon were noted. The fuel ratios of nearly all types of agricultural biomass lay within a range of 0.15-0.30, approximately an order of magnitude lower than those of Zhundong coals, much lower than those of Zhundong coals. There were no significant associations between chemical property and wheat-growing region. In most cases, the ash composition, even for a single biomass type, showed considerable variation, with the K2O content of wheat and corn straw ash being particularly variable. Most Zhundong coals had medium and similar ash fusion temperatures regardless of the changing ash compositions. Contrary to biomass, the Na2O content in Zhundong coal ash was an order of magnitude higher than K2O content. The ash composition of a particular biomass type usually fell in a small region of the ternary diagram of acidic-alkali metal-alkaline earth metal oxide components.