A Novel tool for assessing slagging propensity of coals in PF boilers

Over the years, wide ranges of testing and evaluating procedures have been developed to predict plant performance. Some of the conventional test results and empirical ratios generated out of it offer poorer predictive capability for slagging behaviour experienced in power plants. For better understanding of the coal properties related to slagging problems, a new coal characterization index based on thermo-mechanical analysis (TMA) has been developed in Research and Development Laboratory, BHEL, Tiruchirapalli. A new sampling set up has been designed to carry out shrinkage measurements using TMA. Coal samples collected from various Indian power plants are evaluated. The shrinkage profile of the ash specimen was recorded and characteristic data from the profile were taken for further calculations. Based on proximate analysis, calorific value of the fuels and the shrinkage data of the ash, a new slagging propensity index was proposed. The new index offers better correlation with field observation and hence the new index proposed, offer better predictive capability for understanding the field slagging observations than the conventional indices. The new empirical index can be used as guidelines for relative assessment of coals with respect to slagging, while designing the boiler and tuning the operational parameters.