Numerical Simulation on Combustion and NO x Emission Characteristics of Ammonia/Coal Co‐Firing in a 300‐MW Tangentially Fired Boiler

The ammonia/coal co‐combustion technology aligns with China's national energy condition, which is crucial for China to achieve carbon emission reduction in power plants and meet the “carbon peaking and carbon neutrality goals.” However, due to the distinct combustion characteristics of ammonia compared to traditional fossil fuels, blending ammonia into coal‐fired power plants could lead to combustion instability and increase NO x generation. In the present study, the combustion and NO x emission characteristics of ammonia/coal co‐firing in a 300‐MW tangentially fired boiler were numerically investigated with elucidation on the impacts of NH 3 blending ratio, air distribution strategy, boiler load, load adjustment method and location of ammonia injection. The results indicate that ammonia injection can adversely affect coal burnout. When NH 3 blending ratio is 60%, the coal burnout rate decreases by about three percentage points compared with NH 3 blending ratio at 10%. Too high (more than 30%) or too low (less than 20%) NH 3 blending ratio could raise boiler NO x emissions. The air distribution strategy is of great significance in reducing NO x emissions. When α 1 rises from 0.95 to 1.0, the NO x emissions increase by 223.2 mg·m −3 (6% O 2 ). The coal burnout rate and NO x emissions can better meet energy conservation and emission reduction engineering requirements under the condition that the ammonia blending ratio is 20% and α 1 is 0.95. As the boiler load decreases, ammonia/coal co‐combustion could efficiently decrease boiler NO x emissions and increase the coal burnout rate, which is different from individual combustion of coal. The coal burnout rate increases by 2.2 percentage points with the boiler load reduced from 100% to 70%. In addition, compared with each burner evenly injected with ammonia, concentrated injection of ammonia can exert a significant rise in NO x emissions, with a maximum increase of 449 mg·m −3 (6% O 2 ). The study can offer a certain reference for the low‐carbon transformation of power plants in China.