Effect of dividing single flare tip into multiple tips on soot reduction

Abstract

Several methods are applied for soot reduction in industrial flares. However, they usually involve other issues such as flame safety and other pollutant formations; therefore, they should be handled carefully. Splitting flare tip into multiple branches is an idea that is thought to reduce soot formation by increasing the contact surface and providing better mixing. In this study, changing a single tip of an industrial flare into multiple tips was investigated by Computational Fluid Dynamic software Ansys Fluent 18. Reynolds Average Navier–Stokes approach was used to model the fluid flow, and its turbulence was modeled by realizable k–e model. The steady laminar flamelet model was chosen as the combustion model. Soot formation was modeled using Moss–Brookes approach, and validated by comparing the simulation results with available experimental data. Effects of tip diameter, number of branches, and distance between branches on soot and NOx yields, and flame stability were studied. According to the results, increasing the number of branches having larger diameters by taking flame stability limitations into consideration, and choosing optimum distances between branches caused significant soot reduction without noticeable changes in the NOx formation.