Computational Fluid Dynamics for Simulation of Wind-Tunnel Experiments on Flare Combustion Systems

摘要

Flaring is used extensively in the energy and petrochemical industries to dispose of unwanted combustion gases by burning them in an open flame. However, these units may represent an important source of gas emissions due to inefficient operation under certain conditions such as high crosswind velocities. Several experimental studies have previously focused on flames burning in a fixed volume by using wind tunnels. In these experiments, the entire plume of combustion products was collected, sampled, and analyzed to calculate the combustion efficiency. Present work simulates these wind-tunnel experiments by using the commercial computational fluid dynamics (CFD) software package Fluent 6.2. Several three-dimensional (3D) computational models are developed, and suitable turbulence and chemistry models are applied to simulate the complex combustion phenomena and flame downwash. The computational work was greatly reduced by applying the laminar flamelet model, which assumes that a turbulent flame is an ensemble of small laminar structures called flamelets. Inefficient combustion is observed at high crosswinds, and simulation results are in very good agreement with experimental data. These results show that CFD can successfully simulate these wind-tunnel flare experiments. The resulting simulation models could be used to estimate the hydrocarbon emissions from chemical and petrochemical flares at crosswind conditions, an environmental issue of great importance in air pollution models.