Computational fluid dynamics modeling of laboratory flames and an industrial flare

Abstract

A computational fluid dynamics (CFD) methodology for simulating the combustion process has been validated with experimental results. Three different types of experimental setups were used to validate the CFD model. These setups include an industrial-scale flare setups and two lab-scale flames. The CFD study also involved three different fuels: C₃H₆/CH₄/Air/N₂, C₂H₄/O₂/Ar, and CH₄/Air. In the first setup, flare efficiency data from the Texas Commission on Environmental Quality (TCEQ) 2010 field tests were used to validate the CFD model. In the second setup, a McKenna burner with flat flames was simulated. Temperature and mass fractions of important species were compared with the experimental data. Finally, results of an experimental study done at Sandia National Laboratories to generate a lifted jet flame were used for the purpose of validation. The reduced 50 species mechanism, LU 1.1, the realizable k-ϵ turbulence model, and the EDC turbulence–chemistry interaction model were used for this work. Flare efficiency, axial profiles of temperature, and mass fractions of various intermediate species obtained in the simulation were compared with experimental data and a good agreement between the profiles was clearly observed. In particular, the simulation match with the TCEQ 2010 flare tests has been significantly improved (within 5% of the data) compared to the results reported by Singh et al. in 2012. Validation of the speciated flat flame data supports the view that flares can be a primary source of formaldehyde emission.

Implications

Validated computational fluid dynamics (CFD) models can be a useful tool to predict destruction and removal efficiency (DRE) and combustion efficiency (CE) under steam/air assist conditions in the face of many other flare operating variables such as fuel composition, exit jet velocity, and crosswind. Augmented with rigorous combustion chemistry, CFD is also a powerful tool to predict flare emissions such as formaldehyde. In fact, this study implicates flares emissions as a primary source of formaldehyde emissions. The rigorous CFD simulations, together with available controlled flare test data, can be fitted into simple response surface models for quick engineering use.

Additional information

Notes on contributors

Kanwar Devesh Singh

Kanwar Devesh Singh and Preeti Gangadharan each hold a Ph.D. in chemical engineering from Lamar University, Beaumont, TX.

Preeti Gangadharan

Kanwar Devesh Singh and Preeti Gangadharan each hold a Ph.D. in chemical engineering from Lamar University, Beaumont, TX.

Daniel H. Chen

Daniel H. Chen and Helen H. Lou are professors and university scholars, and Peyton Richmond is an associate professor at Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX.

Helen H. Lou

Daniel H. Chen and Helen H. Lou are professors and university scholars, and Peyton Richmond is an associate professor at Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX.

Xianchang Li

Xianchang Li is an associate professor in the Department of Mechanical Engineering, Lamar University, Beaumont, TX.

Peyton Richmond

Daniel H. Chen and Helen H. Lou are professors and university scholars, and Peyton Richmond is an associate professor at Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX.