Investigating the Effect of Flow Rate Changes on Flare Performance Using Computational Fluid Dynamics Modeling(CFD)

Computational Fluid Dynamics (CFD) is a good numerical tools to solve complicated equations like fluid flows, heat transfer and chemical reactions such as flares issue. In this study, the effect of a changes in the flow rate on flare performance of one of Iran's oil refineries in actual mass flowrate range of 4,000 pounds per hour was calculated using CFD modeling, with Ansys Fluent software 16.0. Also its geometry and mesh designing were carried out by Gambit software 2.4.6. To investigate the effect of changes in flow rate on the flame temperature, flame length, profile of the concentration of combustion species and the turbulent stream pattern in the flame The related calculations are 2D in terms of axis symmetry in which the turbulence was modeled by standard k-ε, Non Premixed Combustion models, Simple Algorithm based on basic pressure and steady state condition were applied and also neglected the effects of the wind. By aid of independant variables from mesh, for actual mass flow ranges, we chose 68700 cells. The simulation results showed that although by changing the mass flow rate, in the range of 4000 pounds per hour does not change the maximum flame temperature. But changes the altitude that happens in this temperature. The length of flame varied in following situation, real mass flow was 14.9 meter which by %10 changes in mass flow, the length displaced 0.66 meter. Therefore, the rate of k (turbulence kinetic energy), ε (loss kinetic energy) increased by increasing the mass flow rate. The distribution of hydrogen and methane constituents in the range of the flame is equal to 1% molar and, with increasing massflow rate both distribution widespread and range of distribution of water and carbon dioxide is 5 and 10%, respectively both Concentrations increased by increasing the mass flow rate.