Concentrations Of Light Hydrocarbons Research Articles

Co-gasification of meat and bone meal with coal in a fluidised bed reactor

After the Bovine Spongiform Encephalopathy illness appeared, the meat and bone meat (MBM) produced from animal residues became an important waste. In spite of being a possible fuel due to its heating value (around 21.4MJ/kg), an important fraction of the meat and bone meal is being sent to landfills. The aim of this work is to evaluate the co-gasification of low percentages of meat and bone meal with coal in a fluidised bed reactor as a potential waste management alternative. The effect of the bed temperature (800–900°C), the equivalence ratio (0.25–0.35) and the percentage of MBM in the solid fed (0–1wt.%) on the co-gasification product yields and properties is evaluated. The results show the addition of 1wt.% of MBM in a coal gasification process increases the gas and the liquid yield and decreases the solid yield at 900°C and 0.35 of temperature and equivalence ratio operational conditions. At operational conditions of 900°C and equivalence ratio of 0.35, the specific yield to gas (ygas) increases from 3.18m3(STP)/kg to 4.47m3(STP)/kg. The gas energy yield decreased 24.1% and the lower heating value of the gas decreases from 3.36MJ/m3(STP) to 2.16MJ/m3(STP). The concentration of the main gas components (H2, CO and CO2) hardly varies with the addition of MBM, however the light hydrocarbon concentrations decrease and the H2S concentration increases at the higher temperature (900°C).

Alteration of crude oils from the Troll area by biodegradation: Analysis of oil and water samples

Biodegradation of crude oil in reservoirs has been extensively studied and is usually considered to be a quasi-stepwise process. The process is known to increase the acidity of the oil. In this paper, results from the analysis of crude oils and co-produced waters from the reservoir surrounding the Troll C platform in the Norwegian North Sea are presented. Based on the concentrations of light hydrocarbons in the Troll oils, simultaneous biodegradation of n-alkanes, branched alkanes, cycloalkanes, alkyl benzenes, alkyl naphthalenes and methyl phenanthrenes is suggested. Pronounced relative enrichment of methylcyclopentane, cyclohexane and methylcyclohexane provide evidence for a specific recalcitrance of cycloalkanes to biodegradation in this field. Biodegradation can also be seen in the carbon isotopic signature of the lighter hydrocarbons, e.g., heavy signatures for n-pentane and iso-pentane. The composition of the aromatic acids in the produced waters suggests biodegradation to be their predominant source in the reservoir. The occurrence of reduced naphthoic acids previously shown to be specific indicators of anaerobic biodegradation of naphthalene, 2-methylnaphthalene and tetralin indicates that the biodegradation took place under anoxic conditions.

Analysis of light hydrocarbons in soil gases, Lost River region, West Virginia: Relation to stratigraphy and geological structures

Analyses of 471 near-surface soil-gas samples for light hydrocarbons, C1–C4, C2L, C3L, and H2 from the Lost River gas field in Hardy County, West Virginia, reveal sites or clusters of sites containing anomalously high concentrations of light hydrocarbon gases, which occur directly over the faulted, eastern limb of the Whip Cove anticline. Compositional changes in the soil-gases data clearly define major changes in the maturity and locations of potential source beds. Grids placed on botanically defined anomalies confirm a possible correlation between these two independent indicators. Statistical analysis shows that samples from 45 sites contain anomalously large concentrations of light hydrocarbons in the soil-gas constituents. Large concentrations, coupled with high saturate-to-olefin ratios, further confirms that this active seepage is near macroseep levels. Variations in soil-gas compositional trends separate the soil-gas data into two domains, with oilier compositions to the west and gassier compositions to the east. Although the composition of the shallow soil gases above the Lost River gas field are oilier than the reservoir gases, they occur directly over the eastern, faulted limb of the producing anticlinal structure, suggesting that the dry gases from the Oriskany reservoir are probably mixed with oilier gases from organic-rich strata among Devonian shales. The eastern anomalies are much gassier and are very similar to the Oriskany gases produced by the Lost River gas field. The eastern anomalies directly overlie near-vertical beds of Devonian and older age formations that are likely conduits for deeper, mature thermal gases.

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 C 2–C 5 light hydrocarbon concentrations to C 2–C 9 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.

Hydrocarbon Leaching, Microbial Population, and Plant Growth in Soil Amended with Petroleum

Two samples of oily waste organics (OWO) from petroleum wells were added to heath soils from Tierra del Fuego, Argentina, and the effects on hydrocarbon leaching, microbial population, and plant growth were studied. These mixtures and a control soil were subjected to four deionized water leachates. For each leachate, total petroleum hydrocarbons (TPH), aliphatic hydrocarbons (ALH), aromatic hydrocarbons (ARH) with three or fewer rings, ARH with more than three rings, and oil and grease (O&G) were measured. After leaching, six Dactylis glomerata L. plants were grown in each soil column. Plant growth and the total number of aerobic and nitrifier microorganisms were measured in soil. The 10% OWO sample increased the TPH in the leachate, but the 1% sample did not. The ALH, ARH, and O&G of each leachate followed patterns similar to that for TPH. Plant growth diminished and the total number of aerobic and nitrifier microorganisms decreased with increasing OWO, especially when the OWO was from a fresh residue rather than an aged residue. The greater inhibitive effect of fresh residue on plant growth was attributed to a higher concentration of light hydrocarbons, which are more toxic than heavy hydrocarbons. For soil with 1% OWO added, the TPH and other organics did not differ from the control soil. This result, combined with the 10-year average annual rainfall and the water table elevation at the site, suggests that the risk of contaminating the water table is relatively low. Thus, a 1% addition of OWO in soil would be appropriate to use in landfarming of OWO.

Applications and limitations of Mango's light hydrocarbon parameters in petroleum correlation studies

Mango (1987) reported on the remarkable invariance of four isoheptanes in petroleums: regardless of the absolute concentration, the ratio of sums of concentration of (2-methylhexane + 2,3-dimethylpentane)/(3-methylhexane +2,4-dimethylpentane) remains constant, the K 1 ratio value being around unity. Gas chromatographic analyses of an additional 500 oils contradict this invariance, as a suite of oils from the Cretaceous Northwest Basin (Argentina) deviate significantly by having a ratio of 1.67. Still, oils derived from the same structural kerogen have invariant ratios that can vary from a lowest value of 0.79 found for the Midland oil set (Mango, 1990) up to a highest value of 1.67 found for the Cretaceous Northwest Basin. Mango (1990) postulated so-called parent-daughter schemes having an invariance in the ratio of isoheptanes and dimethylcyclopentanes, an invariance unique for a homologous set of oils, but possibly distinctly different from another suite of homologous oils. It will be shown here that this difference in invariance can be used in oil/oil correlation studies, and that this technique is especially powerful for oil/condensate correlation, condensates in which the concentration of biological markers is quite often below the limit of detection. Further, the concentration of light hydrocarbons, needed for this approach, can be determined from whole-oil gas chromatography without any pre-treatment, thus providing a rapid and cheap tool for correlation studies.

Combustion Inhibition by Methyl Chloride and the Effects of Steam Injection in a Two Stage Turbulent Flow Reactor

Abstract An experimental and modeling study of the combustion inhibition of CH3Cl and the effects of steam injection in a two stage, turbulent flow reactor is presented. Premixed C2H4, air, and nitrogen with or without CH3Cl were fed to the first stage of the reactor. Steam was injected into the second stage. The feed fuel equivalence ratio was kept constant at 0.6 or 1.3. The loading of CH3Cl was changed from a feed molar CH3Cl/C2H4 ratio of 0 to 0.4. Reactor temperatures and CO, CO2, and light hydrocarbon concentrations were measured at various locations along the reactor. Experiments showed that the presence of CH3Cl inhibited CO burnout and increased the yield of light hydrocarbons. Predicted species concentrations from detailed reaction modeling agree well with the experimental observations. Rate-of-production (ROP) calculations indicate that OH + HCl = Cl + H2O is a major channel for OH consumption. The resulting depletion of OH inhibits the CO burnout reaction OH + CO = CO2 +H2O. Experiments showed...

An Exposure System for the Calibration of Passive Samplers to Volatile Organic Compounds at Low (ppbv) Concentrations

A recycling exposure system, which has characteristics of dynamic and static systems, has been designed and constructed for calibrating passive sampling tubes. This system is very easy to set up and maintain. Organic vapors inside the system are generated by syringe injection, and homogeneous vapors are circulated by a metal-bellows pump. The concentrations of light hydrocarbons (e.g., isoprene) may decrease slightly after circulating for longer than 10 hours; however, this system is very stable for C5-C8 hydrocarbons for at least eight hours. The system has been used successfully to calibrate Perkin-Elmer diffusion tubes packed with Chromosorb 106 for collecting benzene vapor at low exposure doses (< 70 ppmv x min). The entire system can be easily and effectively cleaned by circulating through a U-tube packed with activated carbon.

Geochemical Effects of Light Hydrocarbon Diffusion Into Cap Rock Seals of Hydrocarbon Accumulations: ABSTRACT

Diffusion of low molecular-weight hydrocarbons, especially methane through the water-saturated pore system of sedimentary rocks, is a common and ubiquitous process in the subsurface. Wherever concentration gradients develop, diffusion of mobile components should occur, especially in the contact region between gas-bearing reservoir rocks and overlying caprocks. If the cap rocks were originally devoid or lean in hydrocarbons, one should be able to recognize concentration gradients away from this contact and extending into the cap rock, or, ideally, diffusion haloes within the cap rock stratas. Detailed light hydrocarbon analysis (C/sub 2/-C/sub 8/) of closely spaced samples by the hydrogen stripping technique revealed systematic depth trends for total and individual light hydrocarbon concentrations for a shale cap rock overlying a gas-condensate bearing sandstone in a producing field in North America. A regular relationship appears to exist between the recognized thickness of the enriched interval in the cap rock and the molecular size and type of the considered light hydrocarbon species.

Measurements of selected C2-C5 hydrocarbons in the background troposphere: Vertical and latitudinal variations

Meridional cross sections of the concentration of light hydrocarbons are reported. They were obtained from 20. April to 10. May, 1980, during the French research flight STRATOZ II, and cover the latitudes between 60° N and 60° S and the altitudes between 800 mb and 200 mb. The mixing ratios of ethane, ethene, acetylene, propane, propene, n-butane, i-butane, n-pentane, and i-pentane range between 2.0 and 0.02 ppb. Globally, a decrease in concentration with increasing altitude and -in most cases-with decreasing latitude is observed. In addition the 2-dimensional concentration fields show structures of different scales. In particular, isolated maxima of high concentrations are found in the upper troposphere. They point to fast vertical transport between the boundary layer and the upper troposphere. In the present case these maxima seem to be correlated with large scale meteorological systems, such as low pressure regions or the Inter Tropical Convergence Zone. It is argued that the NMHC provide a set of tracers well suited to the detection of fast vertical transport.

Generation and Migration of Light Hydrocarbons

Light hydrocarbons (containing from 1 to 14 carbon atoms) are formed from disseminated organic matter in sediments at the parts-per-billion level by biological and low-temperature (< 50 degrees C) chemical reactions and at the parts-permillion level by high-temperature (> 50 degrees C) cracking reactions. The cooler reactions produce mainly branched hydrocarbons, whereas the hotter reactions yield more straight chains. Hydrocarbon generation zones in the subsurface can be recognized on the basis of hydrocarbon distribution patterns. Hydrocarbons with tertiary carbon atoms form at lower temperatures than those with quaternary carbons. Methane and ethane migrate vertically through fine-grained shales by diffusion and solution, whereas many of the C(3+) hydrocarbons show little or no vertical migration. Concentrations of light hydrocarbons, including methane, in fine-grained source rocks decrease to low values in deep, high-temperature (>200 degrees C) sediments. This decrease may be one reason why no economic accumulation of gas has been found to date deeper than 8.2 kilometers (27,000 feet).

Light hydrocarbons in Red Sea brines and sediments

Light hydrocarbon (C 1-C 3) concentrations in the water from four Red Sea brine basins (Atlantis II, Suakin, Nereus and Valdivia Deeps) and in sediment pore waters from two of these areas (Atlantis II and Suakin Deeps) are reported. The hydrocarbon gases in the Suakin Deep brine ( T = ~ 25° C, Cl − = ~ 85‰ , CH 4 = ~ 71 1 ) are apparently of biogenic origin as evidenced by C 1 (C 2 + C 3 ) ratios of ~ 1000. Methane concentrations (6–8 μl/l) in Suakin Deep sediments are nearly equal to those in the brine, suggesting sedimentary interstitial waters may be the source of the brine and associated methane. The Atlantis II Deep has two brine layers with significantly different light hydrocarbon concentrations indicating separate sources. The upper brine ( T = ~ 50° C, Cl − = ~ 73‰ , CH 4 = ~ 155 μl/ l) gas seems to be of biogenic origin [ C 1 (C 2 + C 3) = ~1100 ], whereas the lower brine ( T = ~ 61° C, Cl − = ~ 155‰ , CH 4 = ~ 120 μl/ l) gas is apparently of thermogenic origin [ C 1 (C 2 + C 3) = ~ 50 ]. The thermogenic gas resulting from thermal cracking of organic matter in the sedimentary column apparently migrates into the basin with the brine, whereas the biogenic gas is produced in situ or at the seawater-brine interface. Methane concentrations in Atlantis II interstitial waters underlying the lower brine are about one half brine concentrations; this difference possibly reflects the known temporal variations of hydrothermal activity in the basin.

Implications of Gaseous Hydrocarbon Geochemistry of Shallow Core Sediments from Florida-Hatteras Slope: ABSTRACT

Light-hydrocarbon (C1 to C4) concentrations and compositions were determined in sediments from 23 piston cores on the Florida-Hatteras slope and innermost Blake Plateau. On the basis of seismic profiles, cores were taken from slump masses, an accretionary wedge, channel cuts, fault zones, and over a diapir. Maximum total C1 to C4 hydrocarbon concentrations in the sediments analyzed were less than 38 ppm. Light-hydrocarbon concentrations of less than 10 ppm were found in most samples, and methane, ethane, and ethylene were generally the major components. At two sample sites, however, concentrations were greater than 10 ppm. Samples from a channel cut contained hydrocarbons through butane with total C1 to C4 concentrations of nearly 25 ppm. Samples from the diapir site contained mainly methane although ethane and propane were present; the total C1 to C4 concentrations were under 38 ppm. Geochemical surveys that measure light hydrocarbons in surficial sediments have been used as a prospecting tool in offshore petroleum and natural gas exploration. In the shelf and slope areas being considered, background distributions must be established to distinguish anomalous hydrocarbon concentrations that result from natural seeps. Extremely low concentrations of light hydrocarbons and the presence of biologically formed ethylene in the sediments from this study area imply that background levels are possibly due to microbial production of gas from near-surface organic matter rather than by diffusion from underlying petrolific sources. The ubiquitous occurrence of low concentrations, in the ppb range, of the hydrocarbons through butane in slope sediments may arise from microbial p oduction either directly as metabolic by-products or indirectly as degradation products. The possibility that microbes may be related to the occurrence of low concentrations of light hydrocarbons through butane in surface sediments must therefore be considered when evaluating petroleum potential from near-surface data. End_of_Article - Last_Page 1587------------

Sources, sinks, and concentrations of light hydrocarbons in the Gulf of Mexico

A survey of the concentrations of light hydrocarbons in the Gulf of Mexico has been made aboard the R.V. Alaminos of Texas A&M University. The hydrocarbon analyzer consists of a modified Beckman process gas chromatograph with a flame ionization detector. For surface profiling, gases are ‘stripped’ from seawater taken 3 meters below the sea surface by vacuum extraction with a 12-stage booster pump. These gases are injected periodically into the gas stream of the chromatograph for analysis. The system also has the capability of analyzing discrete seawater samples either by the method of McAullife or by the method of Swinnerton and his co-workers. Coastal waters of the Gulf of Mexico are not in equilibrium with the atmosphere insofar as low molecular weight hydrocarbons are concerned, even though methane in most of the open Gulf of Mexico is in fairly close equilibrium with the atmosphere. The coastal waters of the gulf act both as a source and as a sink for atmospheric methane. The important man-derived sources of methane in the gulf are ports with their associated shipping and industrial activity, offshore petroleum drilling and production operations, and open ocean shipping activity. High light hydrocarbon concentrations have been found in the vicinity of a tanker discharging ‘clean ballast water.’ The important natural sources include seepage from oil and gas reservoirs and anaerobic production of methane. The main sink for atmospheric methane in the Gulf of Mexico is in the Yucatan area, where there is major upwelling of deep water with low hydrocarbon concentrations.

Baseline concentrations of light hydrocarbons in Gulf of Mexico

Baseline concentrations of light hydrocarbons in Gulf of Mexico

Mathematical modeling of the absorption process for multicomponent hydrocarbon gases

1. It was shown that the theoretical profiles for the change in temperature and light hydrocarbon concentrations obtained by “plate-to-plate” computer calculations, without taking into account the kinetics of the process, do not correspond to industrial profiles, 2. In view of the lack of a method at this time for carrying out kinetic calculations for the absorption of multicomponent hydrocarbon gases, the possibility and expediency was demonstrated of using the probability-statistical approach for studying this process. 3. It was shown that the temperature profile along the height of the absorber is described by the equation for a cubic parabola for which the coefficients are calculated as a function of the process parameters and the composition of the gas being separated. 4. Approximating relationships were derived for the profiles for the change in the hydrocarbon extraction co-efficients along the height of the absorber which allow the effectiveness of the mass exchange between the gas and the absorber to be evaluated, and make it possible to calculate the composition and amount of gas and absorbent in an arbitrary cross section of the apparatus with an error of 5–6%. 5. The adequacy was established of the given mathematical descriptions for industrial absorbers which operate in the given range of process parameters. 6. The given mathematical model for an absorber can be used in solving problems of intensification, optimization, and automatic control of the process as well as for the technical-economic analysis of the process.