Simulation Research of the Structural Downsizing of SCR Reactor 2017-01-2387

Currently, selective catalytic reduction (SCR) is one of the main after-treatment systems to control diesel engine NOx emission. But the SCR system is bulky, considering the limited installation space. Therefore, the design of SCR system with the compact structure and reliable performance is one of the essential topics. In this study, the structure parameters, such as catalyst cross-sectional area, catalyst length, substrate wall thickness, coating thickness, channels per square inch (CPSI) of substrate, are taken into consideration to study their effects on the SCR performance and narrow the scope of various structural parameters for the following optimization study. Then, the structural parameters of the SCR reactor are optimized by considering the coupling relationship among these structural parameters by using the Response Surface Methodology (RSM) at high load of diesel engine. The numbers of structural parameters are finally optimized as follows: cross-sectional area is 59612 mm²; length is 190 mm; CPSI is 350; coating thickness is 0.01 mm; substrate wall thickness is 0.21 mm. At the same time, NOx conversion rate is 94%; catalyst pressure drop is 733.9 Pa. Compared with the original, catalyst volume is reduced by 31.3%. Optimized structure parameters are validated. The differences between the predicted values and the simulated values of NOx conversion rate and pressure drop are within acceptable limits.