Achieving Simultaneous NOx and Combustion Improvements on a 90MW T-Fired Unit by Applying the Fundamentals

Abstract

Storm Technologies in cooperation with AES Westover Station implemented a total combustion optimization system approach, including a fan boosted over-fire air system on Unit 13 to reduce the emissions of NOx while also improving and/or maintaining acceptable Carbon in Ash content levels on a daily basis. Implementation of this total airflow & pulverizer performance utilized a fundamental and proven approach to performance optimization and the system has been installed now for over two years and continues to be successful. The results of this systems modifications was up to 60% NOx reduction and payback in months by reducing the need for NOx credits and simultaneously improving unit performance, reliability and fuels flexibility. All of the goals of this program were accomplished and the technical success of this project is once again the results of applying a systematic and comprehensive approach addressing fundamental opportunities for improvement. The benefit of this total combustion optimization project was not only NOx reductions, but also reliability and “fuels flexibility”. Furthermore, foresight in this system was the ability to improve boiler efficiency, heat rate and reduce rates of ammonia when and/or if SCR or SNCR is installed. Since the installation of the FBOFA System it should be noted that AES Westover has been able to consistently attain between .25–.30 lbs/mmBtu NOx and single digit carbon in ash levels with no negative effects of the system installed. The goals of this project were as follows: 1. NOx Reduction from >.54lb/mmBtu (full load) – to ≤ 0.32 lb/mmBtu; 2. Flyash Carbon Content less than 10%; 3. Minimal slagging; 4. Operations with a minimum of 2% Oxygen to maintain a “slag friendly” furnace without exceeding the NOx limits; 5. Maximum Load Capability; 6. Maximum Fuel Flexibility; 7. Total Combustion Optimization & Performance Preservation.