Near-source air quality impacts of large olefin flares

Abstract

Large petrochemical flares, common in the Houston Ship Channel (the Ship Channel) and other industrialized areas in the Gulf of Mexico region, emit hundreds to thousands of pounds per hour of highly reactive volatile organic compounds (HRVOCs). We employed fine horizontal resolution (200 m  200 m) in a three-dimensional (3D) Eulerian chemical transport model to simulate two historical Ship Channel flares. The model reasonably reproduced the observed ozone rise at the nearest monitoring stations downwind of the flares. The larger of the two flares had an olefin emission rate exceeding 1400 lb/hr. In this case, the model simulated a rate of increase in peak ozone greater than 40 ppb/hr over a 12 km  12 km horizontal domain without any unusual meteorological conditions. In this larger flare, formaldehyde emissions typically neglected in official inventories enhanced peak ozone by as much as 16 ppb and contributed over 10 ppb to ambient formaldehyde up to $8 km downwind of the flare. The intense horizontal gradients in large flare plumes cannot be simulated by coarse models typically used to demonstrate ozone attainment. Moreover, even the relatively dense monitoring network in the Ship Channel may not be able to detect many transient high ozone events (THOEs) caused by industrial flare emissions in the absence of stagnant air recirculation or stalled sea breeze fronts, even though such conditions are unnecessary for the occurrence of THOEs.Implications: Flare minimization may be an important strategy to attain the U.S. federal ozone standard in industrialized areas, and to avoid inordinate exposure to formaldehyde in neighborhoods surrounding petrochemical facilities. Moreover, air quality monitoring networks, emission inventories, and chemical transport models with higher spatial and temporal resolution and more refined speciation of HRVOCs are needed to better account for the near-source air quality impacts of large olefin flares.

Application of an adjoint neighborhood‐scale chemistry transport model to the attribution of primary formaldehyde at Lynchburg Ferry during TexAQS II

“…The ozone plumes were also much more sensitive to primary formaldehyde when finer resolution was employed. The conclusions of Olaguer [] mitigated the findings of Al‐Fadhli et al . [], who generated a relatively weak ozone response from primary HCHO in industrial flares using a regional air quality model at 1 km resolution.…”

“…No vertical wind beyond turbulent eddies was accounted for in the model. As in Olaguer [, ], the vertical diffusion coefficient was computed using the formula of McRae et al . [] for unstable stratification, with a Monin‐Obukhov length of −100 m and a friction velocity equal to 1/3 of the horizontal wind speed.…”

Author Response to Letter to the Editor

“…My paper, however, referenced Supplemental Materials in which the model chemical mechanism was tested against real world observations during the TexAQS II Radical and Aerosol Measurement Project (TRAMP). The paper also referenced a companion article (Olaguer, 2012b), in which the model predictions were successfully tested against monitoring observations downwind of historical flares in the Houston Ship Channel. The fact that my model is relatively unknown is not a reason to object to my paper, since it is thus far the only 3D Eulerian model that can tractably compute very high resolution ozone impacts near industrial sources.…”

Updated methods for assessing the impacts of nearby gas drilling and production on neighborhood air quality and human health

“…This model, which we refer to as the Houston Advanced Research Center (HARC) model, has been documented and evaluated based on field observations in several publications (Olaguer, 2011(Olaguer, , 2012a(Olaguer, , 2012b(Olaguer, , 2013Buzcu Guven et al, 2013;Olaguer et al, 2013).…”