Characterization of Emissions from Diffusion Flare Systems

Abstract

Emissions from flares typical of those found at oil-field battery sites in Alberta, Canada, were investigated to determine the degree to which the flared gases were burned and to characterize the products of combustion in the emissions. The study consisted of laboratory, pilot-scale, and field-scale investigations. Combustion of all hydrocarbon fuels in both laboratory and pilot-scale tests produced a complex variety of hydrocarbon products within the flame, primarily by pyrolytic reactions. Acetylene, ethylene, benzene, styrene, ethynyl benzene, and naphthalene were some of the major constituents produced by conversion of more than 10% of the methane within the flames. The majority of the hydrocarbons produced within the flames of pure gas fuels were effectively destroyed in the outer combustion zone, resulting in combustion efficiencies greater than 98% as measured in the emissions. The addition of liquid hydrocarbon fuels or condensates to pure gas streams had the largest effect on impairing the ability of the resulting flame to destroy the pyrolytically produced hydrocarbons, as well as the original hydrocarbon fuels directed to the flare. Crosswinds were also found to reduce the combustion efficiency (CE) of the co-flowing gas/condensate flames by causing more unburned fuel and the pyrolytically produced hydrocarbons to escape into the emissions. Flaring of solution gas at oil-field battery sites was found to burn with an efficiency of 62-82%, depending on either how much fuel was directed to flare or how much liquid hydrocarbon was in the knockout drum. Benzene, styrene, ethynyl benzene, ethynyl-methyl benzenes, toluene, xylenes, acenaphthalene, biphenyl, and fluorene were, in most cases, the most abundant compounds found in any of the emissions examined in the field flare testing. The emissions from sour solution gas flaring also contained reduced sulfur compounds and thiophenes.

Gas Flaring in Niger Delta Region of Nigeria: Cost, Ecological and Human Health Implications

“…Ite and Ibok (2013) argued from an operational perspective that about 1.8 billion cubic feet of gas discharged daily in the Niger Delta area is influenced by the energy density of the gas stream, the flare system design, the composition of the gas, and environmental conditions. Their argument is that combustion efficiency depends on the environmental conditions discussed in Strosher (2000), Shore (1996) and Leahey (2001) such as wind speed, stack exit velocity, stoichiometric mixing ratio, and the heating values are seldom successful in realizing complete combustion. The incomplete combustion of the gases generates many volatile organic compounds (VOCs) that wear away the protective waxy Environmental Management and Sustainable Development ISSN 2164-7682 2017 coating on plant leaves.…”

“…The effect of APG flare is documented in the literature of natural resource sustainability including topics on the impact of gas flare on the natural ecology, human health, and the economy. Some of the literature including Strosher (2000), Pohl et al (1986), Karim et al (1985), andMcDaniel (1983) provide perspective on the factors that influence emission, the detection, control, and analytical techniques of the gas flare. Shore (1996), Kindzierski (1999), Leahey et al (2001), andKostiuk et al (2004) find that emissions from flaring are influenced by factors such as the vent design, operating conditions, and chemical combustion.…”

Compositions and greenhouse gas emission factors of flared and vented gas in the Western Canadian Sedimentary Basin

“…In addition to carbon dioxide (CO 2 ), an important greenhouse gas, flares can produce airborne pollutants such as particulate matter in the form of soot McEwen and Johnson, 2012), unburned fuel and carbon monoxide (Johnson et al, 2001;Johnson and Kostiuk, 2000) (especially if the heating value of the flare gas is low (Johnson and Kostiuk, 2002), and potentially other by-products of incomplete combustion (Strosher, 2000). When the raw flare gas contains hydrogen sulfide (H 2 S), the major pollutant sulfur dioxide (SO 2 ) is also produced.…”

Quantifying alkane emissions in the Eagle Ford Shale using boundary layer enhancement

“…Flaring is intended to efficiently dispose of hydrocarbons, resulting in emissions of carbon dioxide as opposed to methane and higher hydrocarbons, including HAPs. However, the high temperatures in flares result in NO x emissions, and inefficient flaring has been shown to release unburned hydrocarbons and NMVOCs produced via pyrolysis (Strosher, 2000;Olaguer, 2012;Pikelnaya et al, 2013).…”