Investigation of Dual LayeredSCR Systems for NOx Control

AbstractNitrogen Oxides (NOx) emissions are one of the major pollutants emanating from industrial plants as well as automobiles. Due to their harmful effect on human health and the environment, strict regulations on the acceptable amount of NOx that can be released from stationary plants have been enacted. Selective Catalytic Reduction (SCR) is an established technology for achieving high NOx reduction from stationary plants. However, due to progressively stringent emissions regulations, the SCR systems need to undergo continuous modifications. Their performance can be improved by gaining better understanding of the various processes that occur within these complex systems. Computational Fluid Dynamics (CFD) provides a cost effective means of achieving this understanding that can be used as a guide for the design of future systems for better NOx conversion from the SCR system. The SCR systems are typically made up of multiple layers of catalyst. While a lot of computational work has been done on the system, most of these previous works were 1-dimensional and 2-dimensional. The present study uses a 3-dimensional model to study the behavior of the SCR system; this will give a more realistic behavior of the SCR system. Furthermore, most work has concentrated on the interactions within a single catalysed channel. This work however, tries to study the influence of a second catalysed layer on the overall performance of an SCR system. The results show that the second catalyst layer plays a vital role in the reduction of NOx as well as ammonia.Hence, the second layer is found to enhance the performance of the system