Advanced SNCR NOx Reduction Experience on Multiple Large Utility Boilers
(Room G109, Auditorium Centre, First Floor)
10 Jun 15
4:00 PM
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5:30 PM
Tracks:
Theme: Coal's Cleaner Future
Fuel Tech has recently completed full-scale applications of Selective Non-Catalytic Reduction systems on a number of large utility boilers (>600MW) firing a variety of fuel types. The systems use the latest flexible injection technology and are controlled with a balanced algorithm utilizing unit load, a full grid of continuous furnace temperatures and the plant continuous emissions monitoring system (CEMS). Recent systems have achieved more than 35% NOx reduction from low baseline furnaces that already utilize primary control measures such as LNB and OFA. This has been accomplished while simultaneously controlling ammonia slip and limiting the use of excess dilution water. Installations have included full contour mapping of the furnace temperatures using either laser-based or acoustic pyrometers to control the system operation, while limiting ammonia slip.
Over the last 15 years, Fuel Tech has completed about 50 installations on units larger than 400MW. Most of these units are larger than 600MW. Large units pose a particularly difficult challenge to SNCR emission control systems, as these modern units generally have higher furnace exit gas temperatures, incorporate low-NOx burners (LNB), over-fired air (OFA) and have very low baseline NOx emissions. Advanced computational fluid dynamics (CFD) and chemical kinetics modeling to design sophisticated injection strategies that anticipate varying load and fuel conditions in the furnace. The analysis is translated into engineering systems that incorporate numerous injector types to deliver the reagent as effectively as possible. The target injection zone varies based on temperature, NOx baseline, CO concentration and furnace residence time.
Specific recent examples will be discussed including the use of on-line temperature mapping, multiple nozzle lances and CFD modeling to provide effective control on large utility furnaces.