Evaluation of effects of ammonia co-firing on the thermal performances of supercritical pulverized coal and circulating fluidized bed boilers

Ammonia is an effective fuel in reducing carbon dioxide due to a carbon-free fuel. Accordingly, the use of ammonia co-firing technology for carbon neutrality has emerged in the power generation industry. It is necessary to determine the optimal operating conditions by analyzing boiler performance during ammonia co-firing for optimal power plant operations. In this study, a process simulation was performed to determine the effect of ammonia co-firing on the thermal performances of supercritical pulverized coal (PC) and circulating fluidized bed (CFB) boilers. The target boilers were 870 and 550 MWe supercritical PC and CFB boilers, respectively. The process simulations were conducted using co-firing ratios of 5, 10, 15, 20, and 30%, as well as various coal grades and load conditions at an ammonia co-firing ratio of 20%. Although the amount of CO₂ reduction during ammonia co-firing was confirmed, the radiation and convective heat transfer rates decreased due to changes in the flue gas composition and due to increased moisture loss. Accordingly, the plant efficiency decreased due to lower main and reheat steam temperatures. These findings can be used to establish optimal operating conditions for CO₂ reduction and improve plant efficiency, which are operational trade-offs during ammonia co-firing.