Practical implications of prior research on today's outstanding flare emissions questions and a research program to answer them

The external combustion of hydrocarbon gas mixtures by any means, including flaring, literally manufactures and subsequently emits to the atmosphere traces of all possible molecular combinations of the elemental constituents present either in the fuel or in the air including the ozone precursor highly reactive volatile organic compounds (HRVOCs) and the carcinogenic hazardous air pollutants (HAPs). In the case of flare operation, this is probably particularly true not only of over-steamed flares but also of Best Practice no-flaring purge-and-pilot-only hot-standby operation. But these trace emissions are hard to measure and in prior related research on hydrocarbon gaseous jet-mixed diffusional combustion have been shown to be trace enough that they pose no threat whatsoever to the public health and welfare. Although recently it has been treated as such by some researchers, regulators and environmentalists, it is hardly a revelation that even burning methane pure as the drifted snow and in the best possible well-mixed way produces trace emissions of ethylene, propylene, butadiene, and all the other highly reactive volatile organics; formaldehyde, benzene and benzo(a)pyrene, the class-archetypal hazardous air pollutant carcinogens; and all the other hydrocarbon compounds in the gas phase up through 300 mw coronene. This will be illustrated by the emissions to atmosphere from the diffusional combustion of natural gas. The severely over-aerated condition (stoichiometric ratio 4.5; i.e., four-and-one-half times theoretical air supplied) may be typical of severely over-steamed flares while the severely under-aerated condition (stoichiometric ratio 0.75; i.e., three-fourths theoretical air supplied) may be typical of Best Practice no-flaring purge-and-pilot-only hot-standby flare operation.