Quantifying flare combustion efficiency using an imaging fourier transform spectrometer
Creators: name: Lapeyre, Paule
name: Miguel, Rodrigo Brenner
name: Nagorski, Michael Christopher
name: Gagnon, Jean-Philippe
name: Chamberland, Martin
name: Turcotte, Caroline
name: Daun, Kyle J
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Space Science
subject: Physical Sciences not elsewhere classified
subject: Biotechnology
subject: Evolutionary Biology
subject: FOS: Biological sciences
subject: Environmental Sciences not elsewhere classified
subject: Chemical Sciences not elsewhere classified
subject: Ecology
subject: Biological Sciences not elsewhere classified
subject: Science Policy
subject: Plant Biology

description: Mid-wavelength infrared (MWIR) imaging Fourier transform spectrometers (IFTSs) are a promising technology for measuring flare combustion efficiency (CE) and destruction removal efficiency (DRE). These devices generate spectrally-resolved intensity images of the flare plume, which may then be used to infer column densities of relevant species along each pixel line-of-sight. In parallel, a 2D projected velocity field may be inferred from the apparent motion of flow features between successive images. Finally, the column densities and velocity field are combined to estimate the mass flow rates for the species needed to calculate the CE or DRE. Since the MWIR IFTS can measure key carbon-containing species in the flare plume, it is possible to measure CE without knowing the fuel flow rate, which is important for fenceline measurements. This work demonstrates this approach on a laboratory heated vent, and then deploys the technique on two working flares: a combustor burning natural gas at a known rate, and a steam-assisted flare at a petrochemical refinery. Analysis of the IFTS data highlights the potential of this approach, but also areas for future development to transform this approach into a reliable technique for quantifying flare emissions. Our research is motivated by the need to assess hydrocarbon emissions from flaring, which is a critical problem of global significance. For example, recent studies have shown that methane destruction efficiency of flaring from upstream oil may be significantly lower than the commonly-assumed figure of 98%; work by Plant et al.<sup>1</sup>1 G. Plant, E. A. Kort, A. R. Brandt, Y. Chen, G. Fordice, A. M. Gorchov Negron, S. Schwietzke, M. Smith and D. Zavala-Araiza, “Inefficient and unlit natural gas flares both emit large quantities of methane,” <i>Science</i>, vol. 377, p. 1566–1571, 2022., in particular, suggest that this discrepancy amounts to CO2 emissions from 2-8 million automobiles annually, considering the US alone. Similarly, the international energy agency (IEA) estimates a global flare efficiency of 92%<sup>2</sup>2 https://www.iea.org/energy-system/fossil-fuels/gas-flaring<sup>3</sup>https://www.worldbank.org/en/programs/zero-routine-flaring-by-2030<sup>4</sup>D.R. Caulton, P.B. Shepson, M.O.L. Cambaliza, D. McCabe, E. Baum and B.H. Stirm, “Methane destruction efficiency of natural gas flares associated with shale formation wells,” <i>Environmental science &amp; technology</i>, vol. 48, p. 9548-9554, 2014.<sup>5</sup>M-A. Gagnon, S.S. Tremblay, P.Lagueux and M. Chamberland, “Standoff thermal hyperspectral imaging for flare and smokestack characterization in industrial environments,” in <i>5</i><sup><i>th</i></sup> <i>workshop on Hyperspectral Image ans Signal Processing: Evolution in remote Sensing</i>, Gainesvilles, FL, 2013, which translates in 8 million tons of CH<sub>4</sub> emitted by flares in 2020. G. Plant, E. A. Kort, A. R. Brandt, Y. Chen, G. Fordice, A. M. Gorchov Negron, S. Schwietzke, M. Smith and D. Zavala-Araiza, “Inefficient and unlit natural gas flares both emit large quantities of methane,” <i>Science</i>, vol. 377, p. 1566–1571, 2022. https://www.iea.org/energy-system/fossil-fuels/gas-flaring <sup>3</sup>https://www.worldbank.org/en/programs/zero-routine-flaring-by-2030 <sup>4</sup>D.R. Caulton, P.B. Shepson, M.O.L. Cambaliza, D. McCabe, E. Baum and B.H. Stirm, “Methane destruction efficiency of natural gas flares associated with shale formation wells,” <i>Environmental science &amp; technology</i>, vol. 48, p. 9548-9554, 2014. <sup>5</sup>M-A. Gagnon, S.S. Tremblay, P.Lagueux and M. Chamberland, “Standoff thermal hyperspectral imaging for flare and smokestack characterization in industrial environments,” in <i>5</i><sup><i>th</i></sup> <i>workshop on Hyperspectral Image ans Signal Processing: Evolution in remote Sensing</i>, Gainesvilles, FL, 2013 Highlighted by these studies and supported by the World Bank<sup>3</sup> initiatives toward zero routine flaring emissions, there is an urgent need for oil and gas industry to assess their flare methane emission, and overall hydrocarbon emissions. At the very least, it is critical to identify problematic flare operating conditions and means to mitigate flare emissions. Focusing on remote quantification of plume species, the measurement technique and quantification method presented in this paper is a considerable step forward in that direction by computing combustion efficiency and key components for destruction efficiency<sup>4,5</sup>.