Influence of coal quality on combustion behaviour and mineral phases transformations

Abstract

Coal is still an important resource for power generation. The combustion behaviour of various types of coal is dependent on its ash properties. These are the most important fuel characteristics in the design and operation of commercial boilers. The present study aims to evaluate the whole coal seam quality, coal ash behaviour, fundamental mechanisms, which more closely simulate the conditions of a pulverised coal-fired boiler. The authors formed seven representative samples from overall 126 band-by-band samples of Prajapara coal block (PCB) borehole of Ib valley coal basin, Odisha, India. Authors have carried technological, elemental and petrographical analysis of coal samples. The major oxides and minerals present in coal ash samples were characterised by inductively coupled plasma optical emission spectrometer (ICP-OES) and X-ray diffraction (XRD). The volatile matter (VMdaf) and ash (A(d)) yields vary from 42.05-44.49 and 30.82-32.12 wt% respectively. The mean vitrinite reflectance ranges from 0.46 to 0.64%. Moreover, FactSage thermodynamics Model (FactSage 6.3) was used for understanding of the coal ash fusion behaviour in boiler operation and to predict the phase transformations that occur during,the process of coal combustion which is a chemical thermodynamic models of oxide systems. FactSage provides mineralogical characteristics of coal which are in agreement with XRD analysis of coal. SiO2, Al2O3, K2O appears to influence positively fusion characteristics where as Fe2O3 and MgO have negative effect on it. The datasets provide information about the contribution of major oxides towards the ash fusion temperatures (AFT). The linear regression analysis of high temperature ash (HTA) composition and AFT indicate trend, which may be used to determine the predictive indices for slagging, fouling, and abrasion propensities during combustion practices. (C) 2016 Elsevier Ltd. All rights reserved.