Model predictive control case study: Selective catalytic reduction (SCR) system in coal-fired power plant

Selective catalytic reduction (SCR) is a leading aftertreatment technology for removal of nitrogen oxides (NO
_x
) from flue gas in coal-fired power plant. In this paper, model predictive control (MPC) strategy is used to optimize the dosing control of ammonia in order to cope with the abrupt change of inlet NO
_x
concentration. Ammonia slip level is utilized as a soft constraint which prevents the reagent over-dosing problem and thus avoiding the corrosion of downstream equipments e.g. the air preheater. Comparisons with conventional control are provided to verify the increased ammonia utilization efficiency.