Design and evaluation of novel static mixers for SCR application

Static mixers are widely used in selective catalytic reduction (SCR) systems to improve the conversion efficiency and service life of the catalyst by better mixing ammonia and the exhaust stream. However, the structure of the mixer needs to be designed carefully to minimise the loss of the system pressure caused by its installation. In this work, experiments and simulations are conducted to evaluate the mixing performance of the static mixers and the system pressure loss. The simulations and experimental results have good agreement. Four novel static mixers are designed and compared with a commercial static mixer to demonstrate their performance. The results show that the box mixer can accomplish less pressure loss (690 Pa) and more homogenous mixing (CoV = 5.4%), and it can thus be used to improve the mixing of ammonia and the exhaust stream in SCR systems.