Reactive and Unreactive Hydrocarbon Emissions from Gas Turbine Engines

Hydrocarbon emissions from gas turbine engines can be divided into unreactive and reactive components. The unreactive component consists of paraffins which do not take part in smog producing reactions with NO_x. The reactive portion includes olefins, aro-matics and oxygenated derivatives of hydrocarbons which take part in smog producing reactions with NO_x. Odor is attributed normally to the aromatics and oxygenates.

Previous work led to the development of a high temperature subtractive analyzer (APCA 22, 696 (1972) which separates hydrocarbon emissions into a) paraffins and b) aromatics, olefins, and oxygenates. Liquid chromatographic techniques have also been used to separate the hydrocarbons into a) aliphatics, b) aromatics, and c) oxygenates. These aliphatics include olefins.

In this work, engine emissions have been analyzed by these two techniques as a function of engine type, engine thrust (power) and fuel type. Specific engines tested were JT4, JT3D and JT9D. Fuels studied were JP5, and Jet A fuel. Power settings ranged from sub idle to high power. Results using the high temperature subtractive analyzer indicate that the % unreactive hydrocarbons ranges from 30 % at idle to near zero at high power for these engine types and fuels. In general, the higher the total hydrocarbon level, the higher the % unreactive hydrocarbons. Total hydrocarbons decrease sharply with increase in thrust. The emissions from different types of engines at various power settings were collected on an adsorbent Chromosorb 102 and the adsorbate analyzed by liquid chromatographic techniques at A. D. Little, Inc. These results showed similar trends from low power to high power. The oxygenate fraction increased and aliphatic portion decreased. However, the data for this portion of the work were very limited and no firm conclusions can be drawn.     

Hydrocarbon emissions speciation in diesel and biodiesel exhausts

Diesel engine emissions are composed of a long list of organic compounds, ranging from C₂ to C₁₂₊, and coming from the hydrocarbons partially oxidized in combustion or produced by pyrolisis. Many of these are considered as ozone precursors in the atmosphere, since they can interact with nitrogen oxides to produce ozone under atmospheric conditions in the presence of sunlight. In addition to problematic ozone production, Brookes, P., and Duncan, M. [1971. Carcinogenic hydrocarbons and human cells in culture. Nature.] and Heywood, J. [1988. Internal Combustion Engine Fundamentals.Mc Graw-Hill, ISBN 0-07-1000499-8.] determined that the polycyclic aromatic hydrocarbons present in exhaust gases are dangerous to human health, being highly carcinogenic.The aim of this study was to identify by means of gas chromatography the amount of each hydrocarbon species present in the exhaust gases of diesel engines operating with different biodiesel blends. The levels of reactive and non-reactive hydrocarbons present in diesel engine exhaust gases powered by different biodiesel fuel blends were also analyzed.Detailed speciation revealed a drastic change in the nature and quantity of semi-volatile compounds when biodiesel fuels are employed, the most affected being the aromatic compounds. Both aromatic and oxygenated aromatic compounds were found in biodiesel exhaust. Finally, the conservation of species for off-side analysis and the possible influence of engine operating conditions on the chemical characterization of the semi-volatile compound phase are discussed.The use of oxygenated fuel blends shows a reduction in the Engine-Out emissions of total hydrocarbons. But the potential of the hydrocarbon emissions is more dependent on the compositions of these hydrocarbons in the Engine-Out, to the quantity; a large percent of hydrocarbons existing in the exhaust, when biodiesel blends are used, are partially burned hydrocarbons, and are interesting as they have the maximum reactivity, but with the use of pure biodiesel and diesel, the most hydrocarbons are from unburned fuel and they have a less reactivity. The best composition in the fuel, for the control of the hydrocarbon emissions reactivity, needs to be a fuel with high-saturated fatty acid content.     

Comparison of vehicle exhaust emissions from modified diesel fuels

Three diesel fuels, one oil sand-derived (OSD) diesel serving as base fuel, one cetane-enhanced base fuel, and one oxygenate [diethylene glycol dimethyl ether (DEDM)]-blended base fuel, were tested for their emission characterizations in vehicle exhaust on a light-duty diesel truck that reflects the engine technology of the 1994 North American standard. Both the cetane-enhanced and the oxygenate-blended fuels were able to reduce regulated [CO, particulate matter (PM), total hydrocarbon (THC)] and nonregulated [polyaromatic hydrocarbons (PAHs), carbonyls, and other volatile organic chemicals] emissions, except for nitrogen oxides (NO(x)), compared with the base fuel. Although burning a fuel that contains oxygen could conceivably yield more oxygenated compounds in emissions, the oxygenate-blended diesel fuel resulted in reduced emissions of formaldehyde along with hydrocarbons such as benzene, 1,3-butadiene, and PAHs. Reductions in nitro-PAH emissions have been observed in both the cetane-enhanced and oxygenated fuels. This further demonstrates the benefits of using a cetane enhancer and the oxygenated fuel component.     

Seasonal impact of blending oxygenated organics with gasoline on motor vehicle tailpipe and evaporative emissions.

Emissions from a 1988 GM Corsica with adaptive learning closed loop control were measured with 4 fuels at 40, 75, and 90 degrees F. Evaporative and exhaust emissions were examined from each fuel at each test temperature. Test fuels were unleaded summer grade gasoline; a blend of this gasoline containing 8.1 percent ethanol; a refiner's blend stock; and the blend stock containing 16.2 percent methyl tertiary butyl ether. The ethanol and MTBE blends contained 3.0 percent oxygen by weight. Regulated emissions (total hydrocarbons, carbon monoxide, and oxides of nitrogen), detailed aldehydes, detailed hydrocarbons, ethanol, MTBE, benzene, and 1,3-butadiene were determined. The highest levels of regulated emissions were produced at the lower temperature. Blended fuels produced almost twice the evaporative hydrocarbon emissions at high temperatures as did the base fuels. Benzene emissions varied with fuels and operating temperatures, while 1,3-butadiene emissions decreased slightly with increasing temperatures. Formaldehyde emissions were not sensitive to fuel or temperature changes. Ethanol fuel blend total aldehyde emissions increased by 40 percent due to increased acetaldehyde emissions. Fuel blends had approximately a 3 percent economy decrease. The MTBE fuel blend appeared to offer the most reduction in total hydrocarbon, carbon monoxide, and oxides of nitrogen for the fuels and temperatures tested.     

Seasonal Impact of Blending Oxygenated Organics with Gasoline on Motor Vehicle Tailpipe and Evaporative Emissions

Emissions from a 1988 GM Corsica with adaptive learning closed loop control were measured with 4 fuels at 40, 75, and 90° F. Evaporative and exhaust emissions were examined from each fuel at each test temperature. Test fuels were unleaded summer grade gasoline; a blend of this gasoline containing 8.1 percent ethanol; a refiner’s blend stock; and the blend stock containing 16.2 percent methyl tertiary butyl ether. The ethanol and MTBE blends contained 3.0 percent oxygen by weight. Regulated emissions (total hydrocarbons, carbon monoxide, and oxides of nitrogen), detailed aldehydes, detailed hydrocarbons, ethanol, MTBE, benzene, and 1, 3-butadiene were determined.

The highest levels of regulated emissions were produced at the lower temperature. Blended fuels produced almost twice the evaporative hydrocarbon emissions at high temperatures as did the base fuels. Benzene emissions varied with fuels and operating temperatures, while 1, 3-butadiene emissions decreased slightly with increasing temperatures. Formaldehyde emissions were not sensitive to fuel or temperature changes. Ethanol fuel blend total aldehyde emissions Increased by 40 percent due to increased acetaldehyde emissions.

Fuel blends had approximately a 3 percent economy decrease. The MTBE fuel blend appeared to offer the most reduction in total hydrocarbon, carbon monoxide, and oxides of nitrogen for the fuels and temperatures tested.     

Speciated Hydrocarbon Emissions from the Combustion of Single Component Fuels. I. Effect of Fuel Structure

Speciated hydrocarbon emissions data have been collected for six single-component fuels run in a laboratory pulse flame combustor (PFC). The six fuels include n-heptane, isooctane (2, 2, 4-trimethylpentane), cyclohexane, 1-hexene, toluene, and methyl-t-butyl ether (MTBE: an oxygenated fuel extender). Combustion of non-aromatic fuels in the PFC (at a fuel/air equivalence ratio of Φ = 1.02) produced low levels of unburned fuel and high yields of methane and olefins (> 75 percent combined) irrespective of the molecular structure of the fuel. In contrast, hydrocarbon emissions from toluene combustion in the PFC were comprised predominantly of unburned fuel (72 percent). With the PFC, low levels of 1, 3-butadiene (0.3-1.8 percent) were observed from all the fuels except MTBE, for which no measurable level (<0.2 percent) was detected; low levels of benzene were observed from isooctane, heptane, and 1-hexene, but significant levels (9 percent) from cyclohexane and toluene. No measurable amount of benzene (< 0.2 percent) was observed in the MTBE exhaust.

For isooctane and toluene the speciated hydrocarbon emissions from a spark-ignited (SI) single-cylinder engine were also determined. HC emissions from the SI engine contained the same species as observed from the PFC, although the relative composition was different. For the non-aromatic fuel isooctane, unburned fuel represented a larger fraction (50 percent) of the HC emissions when run in the engine. HC emissions from toluene combustion in the engine were similar to those from the PFC.     

The Effect of Fuel Composition on Atmospheric Aerosol Due to Auto Exhaust

Aerosols attributable to automobile exhaust can be classified as two types—primary aerosol (initially present in the exhaust) and secondary aerosol (generated photochemically from hydrocarbons and nitrogen oxides in the exhaust). In this study, investigation was made of possible effects of motor-fuel composition on the formation of these aerosols. Secondary aerosol, of principal interest in this work, was produced by irradiating auto exhaust in Battelle-Columbus’ 610 ft³ environmental chamber. A limited number of determinations of primary aerosol in diluted auto exhaust was made at the exit of a 36 ft dilution runnel. Determination of both primary and secondary aerosol was based on light-scattering measurements.

Exhaust was generated with seven full-boiling motor gasolines, both leaded and nonleaded, in a 1967 Chevrolet which was not equipped with exhaust-emission control devices. Changes in fuel composition produced a maximum factor of three difference in light scattering due to primary aerosol. Aerosol yields, for consecutive driving cycles on the same fuel, vary considerably; as a result, ranking the fuels on the basis of average primary aerosol yield was not very meaningful. In addition to fuel composition, the more important independent variables are initial SO₂ concentration, relative humidity and initial hydrocarbon concentration. Statistical analysis of the data indicates that the seven test fuels can be divided into two arbitrary groups with regard to secondary aerosol-forming potential. The fuels in the lower light-scattering group had aromatic contents of 15 and 21%, while those in the higher light-scattering group had aromatic contents of 25, 48, and 55%. Although the fuels can be grouped on the basis of a compositional factor, the grouping of fuels with aromatic content ranging from 25 to 55% indicates that this compositional factor cannot be equated simply with aromatic content. In an associated study of the aerosol-forming potential of individual hydrocarbons prominent in auto exhaust, it was observed that aromatics produce substantially more photochemical aerosol than olefins and paraffins. However, experiments with binar/hydrocarbon mixtures containing aromatjcs, as well as in these exhaust experiments, a strong dependence of aerosol yield on the aromatic components is is not observed. Thus, the data indicate that the dependence of secondary aerosol formation on fuel factors is a complex one and cannot be predicted solely on the basis of a sirigle hydrocarbon component reactivity scale.

The two types of automobile aerosol did not have the same dependence on fuel, composition. The variation in total light scattering attributable to primary plus secondary aerosol was less than that due to either component alone. It therefore was concluded that the light scattering due to automobile exhaust emissions in these experiments was not significantly affected by changing fuel composition.     

Hazardous air pollutants from mobile sources in the Metropolitan Area of Mexico City

Environmental agencies are currently in the process of implementing a new air management program, which includes the improvement of fuel quality. In this work, exhaust emissions data and estimated relative risk for various fuels testing in-use vehicles, equipped with three different exhaust emission control technologies, are presented. Aromatics, sulfur, and olefins contents; type of oxygenated compound; and Reid vapor pressure were varied. The aim also includes calculating the ozone (O3) forming potential and a relative cancer risk of emissions from current and formulated gasoline blends in Mexico. The proposed gasoline decreases carbon monoxide, total hydrocarbons (THC), and nitrogen oxides emissions by 18 and 14%, respectively, when compared with gasoline sold in the rest of the country and within ozone nonattainment metropolitan areas in Mexico, respectively.     

Development of a High-Temperature Subtractive Analyzer for Hydrocarbons

This paper discusses the development of a high-temperature subtractive analyzer for separating the hydrocarbons present in gaseous mixtures into two categories— reactive hydrocarbons and unreactive hydrocarbons. The analyzer utilizes the ability of selected substances to absorb certain groups of hydrocarbons and their derivatives from a gas mixture and is designed for operation with a flame ion-ization detector. The body of information presented in this paper is directed to individuals concerned with the analysis of the exhaust gases of gas turbine engines or other combustion sources as stationary power plants. The analyzer grew out of an investigation of a previously reported subtractive analyzer system which operates at ambient temperature. Current state-of-the-art requirements for the accurate determination of total hydrocarbons at the concentrations present in turbine exhaust gases necessitate that sampling and measurements be conducted at elevated temperatures (325-375°F), rather than ambient temperature, to reduce or eliminate condensation and wall adsorption sampling errors. To fulfill this requirement, the sampling lines and flame ionization detector must be heated. After tests determined that the previously reported scrubber system would not remove the same hydrocarbons at elevated temperature levels as it did at ambient temperatures, an investigation of the effectiveness of various absorbents at elevated temperatures was conducted. This led to the development and test of the high-temperature subtractive analyzer concept discussed in this report. In its final form, one path of this unit contains no absorbent, the second contains a column of concentrated H₂SO₄ on Ultraport and a column containing PdSO₄ and H₂SO₄ on Ultraport. The two columns are connected in series. The absorbents remove olefins, aromatics, acetylene, and oxygenated hydrocarbons but pass paraffins. As the final step in this program, a comparison of the two subtractive analyzers was made using the exhaust from a gas turbine combustion system.     

Analysis for Exhaust Gas Hydrocarbons—Nondispersive Infrared Versus Flame-lonizaticn

An investigation has been made of the suitability of a nondispersive infrared analyzer and two flame-ionization analyzers for measuring the total hydrocarbon concentrations of automobile exhaust gas. The investigation consisted of measuring relative responses of various hydrocarbons, checking for possible exhaust gas interferences and finally comparing exhaust hydrocarbon concentrations indicated by the flame-ionization analyzer to those indicated by the infrared analyzer. The infrared analyzer has high relative responses for parraffins and low responses for olefins, acetylenes, and aromatics. Also, the infrared indicated hydrocarbon concentrations must be corrected for exhaust water vapor interference. When the flameionization analyzers are operated at conditions that result in approximately uniform response to hydrocarbons and low oxygen interference, the exhaust hydrocarbon concentrations indicated by either flameionization analyzer are better approximations of the total hydrocarbon concentration than those indicated by the infrared analyzer.     

Characterization of polycyclic aromatic hydrocarbons from the diesel engine by adding light cycle oil to premium diesel fuel

Diesel fuels governed by U.S. regulations are based on the index of the total aromatic contents. Three diesel fuels, containing various fractions of light cycle oil (LCO) and various sulfur, total polyaromatic, and total aromatic contents, were used in a heavy-duty diesel engine (HDDE) under transient cycle test to assess the feasibility of using current indices in managing the emissions of polycyclic aromatic hydrocarbons (PAHs) from HDDE. The mean sulfur content in LCO is 20.8 times as much as that of premium diesel fuel (PDF). The mean total polyaromatic content in LCO is 28.7 times as much as that of PDF, and the mean total aromatic content in LCO is 2.53 times as much as that of PDF. The total polyaromatic hydrocarbon emission factors in the exhaust from the diesel engine, as determined using PDF L3.5 (3.5% LCO and 96.5% PDF), L7.5 (7.5% LCO and 92.5% PDF), and L15 (15% LCO and 85% PDF) were 14.3, 25.8, 44, and 101 mg L(-1), respectively. The total benzo(a)pyrene equivalent (BaPeq) emission factors in the exhaust from PDF, L3.5, L7.5, and L15 were 0.0402, 0.121, 0.219, and 0.548 mg L(-1), respectively. Results indicated that using L3.5 instead of PDF will result in an 80.4% and a 201% increase of emission for total PAHs and total BaPeq, respectively. The relationships between the total polyaromatic hydrocarbon emission factor and the two emission control indices, including fuel polyaromatic content and fuel aromatic content, suggest that both indices could be used feasibly to regulate total PAH emissions. These results strongly suggest that LCO used in the traveling diesel vehicles significantly influences PAH emissions.     

Effect of gasoline formulation on the formation of photosmog: a box model study

Based on exhaust gas analyses from the combustion of five different types of gasoline in a passenger car operated on a chassis dynamometer, box model simulations of the irradiation of exhaust/NOx/air mixtures using an established chemical mechanism for a standardized photosmog scenario were performed. The fuel matrix used covered wide fractional ranges for paraffinic, olefinic, and aromatic hydrocarbons. Two fuels also contained methyl tertiary butyl ether (MTBE). The different O3 profiles calculated for each run were compared and interpreted. The O3 levels obtained were strongly influenced by the exhaust gas concentrations of aromatic and olefinic hydrocarbons. The higher exhaust content of these compounds caused higher O3 production in the smog system investigated. The conclusion of the present study is that the composition of gasoline cannot be taken directly for the estimation of the emissions' O3 creation potential from its combustion. Variation of the dilution in the different calculations showed evidence for an additional influence of transport effects. Accordingly, further detailed exhaust gas analyses followed by more complex modeling studies are necessary for a proper characterization of the relationship between fuel blend and gasoline combustion products.     

Photochemical Reactivities of Exhausts from 1966 Model Automobiles Equipped to Reduce Hydrocarbon Emissions

During the summer of 1966, a selected group of automobiles from the Cincinnati phase of the GSA study were used in an irradiation chamber study. The study was conducted to evaluate the photochemical air pollution potential of representative models of the equipped and unequipped automobiles. Only one set of automobiles, the unequipped Chevelles, produced exhaust capable upon irradiation of forming significant levels of oxidant and PAN. Neither the equipped Chevelles nor any of the Fords or Plymouths, whether equipped or unequipped, produced exhaust having the characteristics necessary to form oxidant or PAN upon irradiation. The eye irritation level reported by the panel upon irradiation of exhaust from unequipped Chevelles was much higher than that produced by the irradiated exhausts from any of the other types of automobiles. Overall, there does appear to be some small improvement with respect to eye irritation in comparing equipped with unequipped automobiles. To a large extent, the improvement in the air pollution potential of exhaust from equipped Chevelles compared to the unequipped Chevelles can be attributed to the reduction in the hydrocarbon to nitrogen oxide ratio. The irradiated exhaust from equipped Chevelles, except for aldehyde levels, is about the same in photochemical air pollution potential as are the exhausts from both equipped and unequipped Fords and Plymouths which are maintained under lean operating conditions. Such irradiation chamber measurements are related to exhaust not hydrocarbon reactivities. Hydrocarbon reactivities can be obtained by direct measurement of reactive and nonreactive hydrocarbons in the automotive emissions.     

Concentrations of volatile organic compounds in an industrial area of Korea

We measured and analyzed daily mean concentrations of volatile organic compounds (VOC) at Ulsan industrial and downtown sites from 3 to 8 June 1997. The industrial site is situated at the boundary of a petrochemical complex and the other is at downtown area in Ulsan. At each site, we collected ambient air samples in passivated stainless-steel containers by using constant flow samplers and analyzed them by a GC-FID. At Ulsan industrial site, the concentrations and their daily variations of total VOC were higher than those at the downtown site. The concentrations of oxygenated hydrocarbons were the highest among seven hydrocarbon groups at both sites. The fraction of C₂–C₅ light hydrocarbon concentrations to C₂–C₉ hydrocarbons at Ulsan industrial site was higher than that in other industrial areas. It suggests that fugitive emissions of light hydrocarbons in Ulsan industrial areas might be higher than those of other industrial areas. Under favorable wind conditions, the influence of industrial emissions of VOC on the downtown hydrocarbon levels was observed.     

Hazardous Air Pollutants from Mobile Sources in the Metropolitan Area of Mexico City

Abstract

Environmental agencies are currently in the process of implementing a new air management program, which includes the improvement of fuel quality. In this work, exhaust emissions data and estimated relative risk for various fuels testing in-use vehicles, equipped with three different exhaust emission control technologies, are presented. Aromatics, sulfur, and olefins contents; type of oxygenated compound; and Reid vapor pressure were varied. The aim also includes calculating the ozone (O₃)of forming potential and a relative cancer risk of emissions from current and formulated gasoline blends in Mexico. The proposed gasoline decreases carbon monoxide, total hydrocarbons (THC), and nitrogen oxides emissions by 18 and 14%, respectively, when compared with gasoline sold in the rest of the country and within ozone nonattainment metropolitan areas in Mexico, respectively.     

Characterization of emissions from diffusion flare systems

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.     

Characterization of emissions from a variable gasoline/methanol fueled car.

In response to the occurrence of the increasingly severe ambient ozone exceedances, regional environmental managers are examining the possibility of a cleaner fuel for automobiles. At this time the leading candidate appears to be methanol. In anticipation of a shift to methanol, flexible-fueled automobiles capable of operating on gasoline and/or methanol are being developed. This study examines both the exhaust and evaporative emissions from a prototype General Motors Variable Fuel Corsica. Results are reported for tests conducted at temperatures of 40 degrees, 75 degrees, and 90 degrees F, and for fuels M0 M25, M50, M85, and M100. In addition to regulated emissions and fuel economy, emission rates for methanol, aldehydes, and a large number of hydrocarbon compounds were measured. The data indicate that increasing the fuel's methanol content does not affect the exhaust organic emission rate (calculated in accordance with the regulation) from flexible-fueled cars, but formaldehyde and methanol comprise increasingly greater portions of the organic material while hydrocarbons comprise less. Increasing fuel methanol content has no significant effect on exhaust regulated emission rates (organic material, carbon monoxide, and nitrogen oxides) nor on the composition of total hydrocarbons, except for methane, which increases substantially. The effect of ambient temperature on both exhaust and evaporative emissions is similar to its effect on gasoline cars: organic and carbon monoxide exhaust emissions increase substantially at the lower temperatures, and evaporative emissions increase steadily with increases in temperature.     

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, eth-ylene, 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.     

Characterization of Polycyclic Aromatic Hydrocarbons from the

Abstract

Diesel fuels governed by U.S. regulations are based on the index of the total aromatic contents. Three diesel fuels, containing various fractions of light cycle oil (LCO) and various sulfur, total polyaromatic, and total aromatic contents, were used in a heavy-duty diesel engine (HDDE) under transient cycle test to assess the feasibility of using current indices in managing the emissions of polycyclic aromatic hydrocarbons (PAHs) from HDDE. The mean sulfur content in LCO is 20.8 times as much as that of premium diesel fuel (PDF). The mean total polyaromatic content in LCO is 28.7 times as much as that of PDF, and the mean total aromatic content in LCO is 2.53 times as much as that of PDF. The total polyaromatic hydrocarbon emission factors in the exhaust from the diesel engine, as determined using PDF L3.5 (3.5% LCO and 96.5% PDF), L7.5 (7.5% LCO and 92.5% PDF), and L15 (15% LCO and 85% PDF) were 14.3, 25.8, 44, and 101 mg L^?1, respectively. The total benzo(a)pyrene equivalent (BaP_eq) emission factors in the exhaust from PDF, L3.5, L7.5, and L15 were 0.0402, 0.121, 0.219, and 0.548 mg L^?1, respectively. Results indicated that using L3.5 instead of PDF will result in an 80.4% and a 201% increase of emission for total PAHs and total BaP_eq, respectively. The relationships between the total polyaromatic hydrocarbon emission factor and the two emission control indices, including fuel polyaromatic content and fuel aromatic content, suggest that both indices could be used feasibly to regulate total PAH emissions. These results strongly suggest that LCO used in the traveling diesel vehicles significantly influences PAH emissions.     

Careers in Air Pollution Control Plant Pathology

ABSTRACT

Profiles of the sources of nonmethane organic compounds (NMOCs) were developed for emissions from vehicles, petroleum fuels (gasoline, liquefied petroleum gas [LPG], and natural gas), a petroleum refinery, a smelter, and a cast iron factory in Cairo, Egypt. More than 100 hydrocarbons and oxygenated hydrocarbons were tentatively identified and quantified. Gasoline-vapor and whole-gasoline profiles could be distinguished from the other profiles by high concentrations of the C₅ and C₆ saturated hydrocarbons. The vehicle emission profile was similar to the whole-gasoline profile, with the exception of the unsaturated and aromatic hydrocarbons, which were present at higher concentrations in the vehicle emission profile. High levels of the C₂-C₄ saturated hydrocarbons, particularly n-butane, were characteristic features of the petroleum refinery emissions. The smelter and cast iron factory emissions were similar to the refinery emissions; however, the levels of benzene and toluene were greater in the former two sources. The LPG and natural gas emissions contained high concentrations of n-butane and ethane, respectively. The NMOC source profiles for Cairo were distinctly different from profiles for U.S. sources, indicating that NMOC source profiles are sensitive to the particular composition of petroleum fuels that are used in a location.