Prediction of Carbon Emissions from Coal-Fired Power Plants During Load Cycling with Varying Coal Characteristics

With the evolvement of the coal marketplace and massive growth in renewable resource power, conventional coal-fired generation is facing challenges in the operation of fluctuating loads and varying coal characteristics. The intent of this study is to predict carbon emissions from coal-fired power plants during load cycling and the operation of varying coal characteristics. The given correlation was revised by adding a new nitrogen term and using thermodynamic data from the latest JANAF tables. On the basis of the revised correlation, the quantitative impact of each element composition of coal on the carbon emission factor was worked out according to first-order Taylor series approximation. The O/C and H/C ratio of coal at the lowest carbon emission factor was evaluated in the VAN Krevelen diagram, showing that coals have the lowest carbon emission factor value of roughly 23.25 kg/GJ GCV at atomic O/C and H/C ratio values of about 0.08 and 0.98, respectively. Correlations of carbon emission with the proximate analysis of coal were established through stepwise linear regression using 247 coals for power generation. Based on the varying nature of the net heat rate with load condition expressed by the generic model derived from 11 typical units in-service, the impact of coal and load cycling on carbon emission was captured with a developed equation. Linking the above investigation to a study in a thermal power unit with a rated output of 1000 MW shows that the total variation of carbon emission due to the combined effect of coal and load cycling could be 27.44% if the unit cycles at 35% to 100% rated output with coal normally varying in the present context.