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Show T Design, Optimization and Economic Analysis of S N C R / S C R Hybrid on a Utility Boiler in the Ozone Transport Region J. Urbas GPU G E N CO 1001 Broad Street Johnstown, Pennsylvania 15907 John M. Boyle Fuel Tech, Inc. P.O. Box 3031 Naperville, Illinois 60566 1998 American/Japanese Flame Research Committees International Symposium Abstract A full-scale SNCR/SCR Hybrid system, NOxOUT CASCADE, has been designed and installed at the G P U G E N C O Seward Station, Unit #15 boiler. The Seward Station hybrid system is a combination of a redesigned existing S N C R with a new downstream SCR. Significant improvements in chemical utilization and overall N O x reduction have been seen in preliminary testing of the S N C R when ammonia slip was permitted to increase above normal operational limits. The integrated system was designed using advanced computational fluid dynamics and cold flow modeling techniques. The units two air pre-heater ducts were retrofit with different types of catalyst, honeycomb in one and plate in the other. Reactor and duct internals were designed to compensate for an existing ash loading imbalance, temperature and velocity variation, and a difference in the S C R pressure drop between the two ducts. Introduction The Clean Air Act Amendments of 1990 have given rise to a wave of technology development that anticipates meeting clean air challenges. In the first half of this decade, the U.S. witnessed the retrofit of low N O x burners on coal, oil, and gas-fired boilers. Additionally, there were new developments in air staging technologies, gas reburn demonstrations under the Clean Coal Technology Program, in-field applications of S N C R retrofit on various types of utility boilers, and even a retrofit application of S C R on a cyclone coal-fired boiler. Industry observers predict large costs will be borne by major sources to meet the air quality goals in some Phase II provisions of the Act In preparation for "life beyond Phase I," field development is now being focused on effective combinations of N O x controls. Potentially, two or more available means of N O x control can be compatibly combined to reduce N O x wherein the end result is more cost effective than the sum of its parts. Hybrid combinations of S N C R and S C R are a particularly flexible method for effecting moderate to deep reductions of N O x at cost ranges typically below those of a fully-engineered S C R retrofit. This paper presents a discussion of the implementation of a SNCR/SCR hybrid at the GPU G E N C O Seward Station and the expected increase in N O x reduction performance and chemical utilization. The design was based on minimizing the total life cycle cost while achieving the required control. Page 1 |