“The overall goal of both of these systems, whether it’s an SCR or SNCR system, is to reduce the NOx generated by a combustion source, such as boilers, gas turbines, or engines,” Broderick said. “The SNCR process is a higher temperature process that does not require a catalyst but is slightly less efficient. The SCR process uses a catalyst to mix the exhaust and ammonia, and it is a much more efficient reaction, but it happens at a lower temperature.”
Safety, availability, environment and cost are all factors when choosing a system that utilizes either ammonia, hydrous ammonia or urea.
Before selecting the right method for NOx reduction, it is essential to consider all aspects and potential safety hazards.