Optimization of SCR system at Cayuga Unit 1

Carlos E. Romero, Zheng Yao, Fengqi Si, Eugenio Schuster, Robert L. Morey, Jacob A. Peter, Barry N. Liebowitz

International Pittsburgh Coal Conference

Pittsburgh, Pennsylvania, September 29-October 2, 2008

Abstract

AES Cayuga Unit 1 is a 160 MW unit, equipped with a low-NOx firing system and an anhydrous ammonia (NH3), Selective Catalytic Reduction (SCR) system for NOx emissions control. A combined boiler/SCR/air preheater (APH) optimization was performed to minimize the cost of NOx emissions control. Boiler and low-NOx system control settings, and SCR and air preheater (APH) operating conditions were included in a parametric test program. Information from a Breen Energy Solutions ammonium bisulfate (ABS) probe was also included for monitoring of ABS formation in real-time and as a constraint to the SCR optimization. The parametric test data were used as the basis for the optimization that consisted of an approach that incorporates accurate on-line support vector regression (AOSVR) modeling for adaptive learning, and genetic algorithms for implementation of the multi-objective optimization. The results indicate that optimal operating conditions can be achieved for a coordinated boiler/SCR/APH operation, and minimal NH3 consumption, maximum SCR performance, and optimal net unit heat rate, subject to minimal impact on fly ash unburned carbon content, mitigated ABS formation, and other operational and environmental constraints. The optimal conditions resulted in reduced NH3 usage of the order of 25 percent, with improved APH fouling management.