Mixing Quality Improvement of a Coaxial Syngas Mixer by Adding Optimized Mechanical Tabs Using Three-Dimensional CFD Modeling

A coaxial gas mixer is designed for mixing air and synthesis gas or syngas as fuel. Three-dimensional computational models are harnessed to analyze and predict the influence of the mechanical tabs aspect ratio and number on the mixing characteristics and performance of the gas mixer. Attention is concentrated on the influence of mechanical tabs on the air-fuel ratio, pressure loss and mixing quality. The optimum design of the mechanical tab was realized with aspect ratio of 0.32 and 4 tabs with 45o tab angle. The coaxial gas mixer using the optimized mechanical tabs was realized with λ of 1.13 corresponding to pressure loss of 37.2 Pa at 100 m3/h air-flow rates and the coefficient of variation (CoV) of mixing was 0.29. The gas mixer with the mechanical tabs had much better mixing performance than the gas mixer without mechanical tabs with only relatively small increase in pressure loss.