Experimental investigation of slagging and fouling in co-combustion of bituminous coal and sorghum waste: Insights into ash morphology and mineralogy

This research critically explored the co-combustion of bituminous coal and sorghum waste, contributing to the ambitious goal of clean power generation to achieve a low-carbon society. In addressing the challenges associated with ash-related issues during combustion, the primary objective of the study is to identify the specific elements and minerals responsible for these problems. The risk indices of these ash-related issues were determined through an hour combustion experiment employing a drop tube furnace using bituminous coal and sorghum waste blend at mass ratios of 5, 10, 15, 20, and 25 % and temperature of 1473 K. During the experiment, the accumulated ash deposits were analyzed to assess their slagging and fouling tendencies at probe temperatures of 873 and 823 K, respectively. Through detailed analysis, three key elements and six mineral types were identified as the main contributors to ash deposition. Based on these findings, the research established new thresholds for acceptable element and mineral levels of slagging and fouling tendencies. Specifically, the maximum acceptable element level for low slagging risk was set at 8 %, while the fouling risk associated with specific elements is limited to 6 %. Furthermore, the threshold for specific mineral accumulation was set at 10 % for low slagging tendency and 15 % for low fouling tendency. The qualitative assessments and the classification of safe elements and minerals composition in samples indicate that up to 15 wt% sorghum blend is considered safe from the risk of slagging and fouling. These findings offer valuable insights for improving coal-sorghum cocombustion's efficiency and environmental impact in power generation.