Influence of biomass addition on Jincheng coal ash fusion temperatures

• Ash fusion temperatures of Jincheng coal and biomass (cotton stalk and sargassum natans) blends were investigated.
• The fusion temperatures of biomass and coal blending ash were lower than their individual ash.
• Base to acid ratio (B/A) was related to the fusion temperatures.
• The ash fusion mechanisms were discussed by minerals transformations.

The ash fusion temperatures (AFTs) of Jincheng (JC) coal, two kinds of biomass (cotton stalk (CS) and sargassum natans (SA)) and various coal–biomass mixtures were investigated in this study. Fluid temperatures (FT) were found 1531 °C, 1534 °C and 1428 °C for JC, CS and SA ash respectively, which were higher than the normal operating temperature of entrained bed gasifier. However, the FTs of JC and CS mixture ash were lower than that of either single JC or CS ash, which showed a minimum value of 1292 °C with 80% CS, and the FTs of JC and SA mixture ash showed the similar trend with a minimum value of 1258 °C when SA proportion was 40%. At high temperature, refractory minerals were presented in three respective ashes, which were mullite of JC ash, lime and periclase of CS ash, merwinite and akermanite of SA ash. And they could support the ash skeleton structure. Interaction between coal and biomass ash occurred during blending ash melting process, which formed co-eutectic and decreased the AFTs. The relationship between the ash fusion temperatures and the ash chemical composition was also discussed.