Dispersion aspects of NH3-delivery strategies for NH3-based SCR systems

Artikel i vetenskaplig tidskrift, 2013

The current work investigates the performance of an NH3-based SCR-system for two different NH3-delivery strategies, based on either urea or gaseous ammonia, using computational fluid dynamics (CFD). Quantification of the radial uniformity of NH3 shows that the system based on gaseous ammonia is capable of providing a more even NH3-profile. It is also shown that the uniformity obtainable in a urea-SCR system may be substantially enhanced by the introduction of a static mixer. Furthermore, the results indicate that the expected negative influence on the radial uniformity of a gas-based system from a decreased retention time before the catalyst is counterbalanced by an increased radial mixing. In addition, two theoretically derived "rule of thumb"-relations for estimating the performance of SCR systems are presented and their use in the interpretation of the CFD data is illustrated.