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ABSTRAK Azaria Haykal Ahmad
PUBLIC Irwan Sofiyan

Coal-fired power plants are significant contributors to global CO2 emissions, necessitating the exploration of innovative methods to mitigate their environmental impact. Ammonia combustion has emerged as a promising technology for CO2 reduction in such power plants. This research explores the optimum injection location and fraction of ammonia in a 1000 MW Ultra Super Critical Coal-Fired Power Plant through computational fluid dynamics (CFD) simulations . The study aims to evaluate the effects of ammonia injection location and fraction based on key parameters, such as flame shape, gas temperature, and emission characteristics. By systematically varying the injection location and fraction, the research seeks to identify the optimal configuration that achieves enhanced CO2 reduction and improved combustion efficiency.Through the CFD simulations, the behavior and interaction of ammonia with the coal combustion process can be comprehensively analyzed. The simulations enable the examination of flame dynamics, including flame shape and temperature distribution, providing insights into the effectiveness of different injection strategies. Initially, four different injection locations, namely equally divided, top burner, bottom burner, and mid burner, were investigated under a thermal energy co-firing ratio of 20%. Through comprehensive analysis and experimental investigations, it was determined that the bottom burner injection location yielded the lowest NOx emissions among the studied locations. In addition, the sensitivity analysis of other burner level also has been analysed, and result in majority injection in the bottom burner, followed by mid burner has better performance than equal divided in the mid and top burner, Building upon these findings, the study focused on varying the injection location, with particular emphasis on the bottom burner. The effect of ammonia co-firing ratio ranging from 5% to 60% on NOx emissions was carefully examined. Examining the impact on gross power and derating, a gradual decrease in gross power emerged as co-firing ratio escalated. Derating was quantified through linear regression, revealing a 3.6 MW reduction per 1% co-firing ratio. The need to align economizer outlet gas temperatures fueled this derating process, stemming from varying heat absorption and heightened water content resulting from ammonia combustion. Flue gas temperature and composition bore the hallmark of ammonia co-firing. The lower flame temperature linked to ammonia yielded cooler flue gas and furnace temperatures. Furthermore, increased water vapor content, reduced nitrogen concentrations, and shifts in CO2 and CO emissions underscored the influence of ammonia introduction. Turning to NOx emissions and conversion ratios, a complex trend unfolded. Initial co-firing led to NOx reduction up to 20%, attributed to ammonia's NOx reduction capability. However, beyond this threshold, NOx surged dramatically, surpassing regulatory limits at a 60%.cal co-firing ratio. NOx conversion ratios exhibited stability beyond 20%.cal co-firing, providing a valuable reference point for emission management. The burnout ratio increases linearly due to the very low unburn ammonia. However, in coal burnout, the trend increases, then after 40%.cal, it decreases. This phenomenon was ascribed to the presence of the char-NO reaction, counteracting the diminished coal volatilization caused by elevated ammonia levels. Acid dew point analysis disclosed concerning trends as higher co-firing ratios lowered dew point temperatures, inviting acid corrosion and fouling risks. The inadequacy of sustaining a constant economizer outlet temperature underscored the need for enhanced derating strategies for safety and acid condensation prevention.