Impact of Flare Destruction Efficiency and Products of Incomplete Combustion on Ozone Formation in Houston, Texas

The impact of flare destruction removal efficiency (DRE) and Products of Incomplete Combustion (PICs) on ozone formation was examined using a regional photochemical model. Emission scenarios for five industrial flares were considered. For each flare, four DRE values (95, 90, 75, and 50%) were assumed, along with a base case that assumed 98 or 99% DRE. For each DRE level, a scenario assuming that no PICs and a scenario assuming a level of PICs consistent with full scale flare tests was evaluated. Simulation results indicated that low DREs can increase ambient ozone concentrations by more than 15 ppb under some conditions, but under other conditions, may raise ozone concentrations by 1 ppb or less. Emission rates of unburned flare gases and the chemical reactivity of the unburned hydrocarbons explain much of the variability in ozone formation. The air quality simulations also showed that unburned flare gases can have a larger impact on ozone formation than PICs.