High Efficiency and Low Cost NOx Control via Promoted N-Agent Injection

Prospective technologies for stationary post-combustion NOx control include: Selective Non-Catalytic Reduction (SNCR) and Selective Catalytic Reduction (SCR). These processes reduce NOx by non-catalytic or catalytic reactions with N-Agents (ammonia or urea). There are several problems with SCR, such as high capital cost, limited catalyst life, catalyst poisoning, and disposal. SNCR is less expensive, but capabilities of SNCR are limited by the narrow temperature window of NOx control, ammonia slip, low utilization (about 27%) of N-Agents, and formation of N2O with urea injection. This Phase I project is directed towards improving performance of the SNCR process in the presence of promoters. The project will demonstrate that the Promoted N-Agent injection process can eliminate or minimize all of the limitations described above. The promoters are water soluble inorganic salts, which are added in small quantities to the N-Agent solution. The goal of the project is to achieve 90% NOx removal in pilot scale with less than 5% promoter concentration from initial N-Agent level at less than 5 ppm NH3/N2O emissions while utilizing at least 60% N-Agent. In a combination with other inexpensive NOx control methods (such as low NOx burners and/or reburning), the process makes it possible to reduce NOx by more than 95%. Cost analysis indicates that the Promoted N- Agent injection process is significantly less expensive than competing technologies. Its cost, in terms of $/ton of NOx removed, is lower by a factor of 2 than the cost of conventional SNCR and a factor of 6 in comparison with SCR.