Numerical study on ammonia injection location of ammonia and low-rank coal cofiring in 1000 MWe ultra super critical carolina-type boiler

Abstract

Global CO2 emissions from coal-fired power plants necessitate innovative solutions to reduce their environmental footprint. Ammonia cofiring has emerged as a promising solution for reducing CO2 emissions in these plants. The ammonia injection optimization is analyzed using computational fluid dynamics simulations in a 1000 MW Ultra Super Critical Coal Fired Power Plant, comparing four injection sites at a 20 % thermal energy cofiring ratio. Results indicated the bottom burner as the most effective location, achieving the lowest NOx emissions (102.20 mg/Nm3) compared to traditional coal-firing (131.78 mg/Nm3). A sensitivity analysis favored bottom and mid burner injections over equal distribution, leading to further investigations into varying injection locations and cofiring ratios (5%–60 %). Increased cofiring ratios decreased gross power output by 3.6 MW per percentage increase in cofiring, alongside shifts in flue gas properties and a complex NOx emission trend. Initially, NOx emissions decreased, with a 0.784 up to 20 % cofiring, but dramatically increased beyond, reaching a ratio of 3.744 at 60 % cofiring. This study reveals critical insights into emission management and highlights the need for improved derating strategies to mitigate acid corrosion risks, marking a significant step towards environmentally sustainable coal power generation.