Optimizing nozzle designs to improve upstream turbulent mixing and downstream combustion efficiency in flares

Inefficient combustion of methane flares due to sub-optimal conditions can lead to significant emissions contributing to climate change. Current regulations require 96.5%

combustion efficiency of waste gases, yet typical conditions (such as variable flow rates, changes in gas composition, and turbulent cross wind) make this an arduous task. Inadequate

monitoring and control systems pose significant challenges in achieving desired operational states. In the current work, we present results from experiments and numerical simulations that quantitatively link nozzle design with mixing of waste-gas and ambient air and downstream combustion efficiency. Large-eddy simulations combined with a flamelet progress variable approach (FPVA) is employed to simulate laminar and turbulent methane flares, and are compared with species measurements using gas sampling and gas

chromatography and velocity measurements using particle image velocimetry (PIV) from the experimental campaign. The comparisons are made for a canonical case and the near-nozzle mixing is studied, quantified by the scalar dissipation rate and scalar variance norm, along with the effect on combustion efficiency, which is defined as the percentage of methane converted into carbon dioxide and water during the combustion process.