Rich Reagent Injection (RRI)
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Urea Injection in Lower Furnace on Cyclone-Fired Boilers
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High Injection Rates
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Minimal to no Ammonia Slip
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25% - 40% NOx Reduction
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Up to 60% NOx Reduction when Combined with SNCR
Process
Rich Reagent Injection (RRI) is the process of adding NOx reducing agents in a staged lower furnace to reduce the formation of NOx. This is accomplished by injecting urea into the fuel-rich region of a furnace, where the reducing conditions and low oxygen levels in the lower furnace make RRI ideal for NOx reduction. The combustion process is then completed with the use of over-fire air.
RRI technology is licensed through the Electric Power Research Institute. RRI is similar to Fuel Tech’s NOxOUT® SNCR process, which involves the injection of urea reagent at temperatures between 1700° and 2100°F. However, in the RRI process, reagent injection occurs at significantly higher gas temperatures within the combustion zone of the lower furnace (2400°-3100°F). The flue gas stoichiometric ratio (SR) in the lower furnace will be fuel rich, with the SR less than 1. The RRI process results in little to no ammonia slip in comparison to SNCR. The reagent consumption with RRI is higher than SNCR, with a normalized stoichiometric ratio (NSR) of approximately 2 compared to a typical NSR of 1 for SNCR.
Results
Eight commercial installations are in operation on cyclone fired boilers with results that exceeded commerical performance.