Work

Performance optimization of static mixer in urea-SCR system considering flow and turbulence characteristics

Year: 2025

Type: article

Abstract: The urea-Selective Catalytic Reduction (SCR) system is known to be the most proven technology, among the various de-NOx technologies in diesel engines. Since hydrogen and ammonia fuel are focused on every thermal system for carbon neutral policy, thermal NOx by hydrogen, and fuel NOx by ammonia would be increased. In the urea-SCR system, the NOx reduction efficiency depends on the NH3 concentration and velocity uniformity in the catalyst layer. Therefore, the flow characteristics of blockage ratio (BR) were evaluated by the blade geometry of a static mixer used in the 2 MW class urea-SCR system. Mixing performances and flow by characteristics were investigated using numerical analysis. As a result, swirl flow was formed by the complex interaction between two blades (Blades #1 and #2) due to the geometry characteristics of the static mixer. Blade #1 increased UIvel by 8.8% compared to Blade #2, and Blade #2 increased TI by 28.5% compared to Blade #1. In addition, the influence of blade offset was analyzed. Accordingly, the intensity of the interaction between the two blades changed in the area between Blades #1 and #2. As blade offset increased, back pressure decreased by 37.5% in all BRs, and the reactor’s inlet UIvel decreased by 5.9%, 5.6%, and 3.5% in B50, B45, and B40, respectively. The cases satisfying all constraints with the maximum mixing performance were “B40-1-0.9D” or “B40-1-1.2D”.

Source: Results in Engineering

DOI: 10.1016/j.rineng.2025.104951