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Combustion Products (combustion + products)
Selected AbstractsCharacterization of the combustion products in large-scale fire tests: comparison of three experimental configurationsFIRE AND MATERIALS, Issue 2 2001Per Blomqvist The storage of large amounts of polymers and other bulk chemicals is a potential hazard in the case of fire. There is at present a lack of knowledge about the implications of such fires. In particular the role of the ventilation conditions on fire chemistry has warranted investigation. A set of indoor, large-scale combustion experiments, conducted on five different materials is described in this article. The main test series was conducted using the ISO 9705 room, where both well-ventilated and under-ventilated conditions were attained by restricting the opening of the room. The degree of ventilation was determined using a phi meter. Furthermore, in addition to measuring the traditional fire-related parameters, extensive chemical characterization of the combustion products was made. Two additional series of experiments were also performed. In one series of tests the size of the enclosure was increased and the fuel was placed in a storage configuration to simulate a real storage situation. In the other test series, three of the materials were tested as large-scale open pool fires. The results from the three configurations are compared regarding yields of combustion products as a function of the degree of ventilation. For a number of toxic combustion products a clear dependence of the production on the equivalence ratio was found. Further, placing the fuel in a storage configuration did not significantly change the outcome of the combustion. Thus, the ISO 9705 room is of a size and scale that can be taken as a model for representing real-scale fires. Additionally it has been demonstrated that an advantage of the ISO 9705 room is the ability to alter the ventilation conditions. Copyright © 2001 John Wiley & Sons, Ltd. [source] Millisecond catalytic reforming of monoaromatics over noble metalsAICHE JOURNAL, Issue 4 2010C. M. Balonek Abstract The millisecond autothermal reforming of benzene, toluene, ethylbenzene, cumene, and styrene were independently studied over five noble metal-based catalysts: Pt, Rh, Rh/,-Al2O3, Rh,Ce, and Rh,Ce/,-Al2O3, as a function of carbon-to-oxygen feed ratio. The Rh,Ce/,-Al2O3 catalyst exhibited the highest feedstock conversion as well as selectivities to both synthesis gas and hydrocarbon products (lowest selectivities to H2O and CO2). Experimental results demonstrate a high stability of aromatic rings within the reactor system. Benzene and toluene seem to react primarily heterogeneously, producing only syngas and combustion products. Ethylbenzene and cumene behaved similarly, with higher conversions than benzene and toluene, and high product selectivity to styrene, likely due to homogeneous reactions involving their alkyl groups. Styrene exhibited low conversions over Rh,Ce/,-Al2O3, emphasizing the stability of styrene in the reactor system. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Polycyclic aromatic hydrocarbon residues in the sediments of a dune lake as a result of power boatingLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 1 2001Thorsten D. Mosisch Abstract The potential chemical effects of motorized recreational activities (power boating, water skiing, jet skiing) on Brown Lake, an Australian perched, acid dune lake, were investigated. The objective of this study was to identify and quantify polycyclic aromatic hydrocarbon compounds (PAHs) that may have accumulated in the water and/or the organic bottom sediments of the test lake as a result of the operation of powered recreational watercraft, and to evaluate any risk to aquatic biota. To achieve this, a detailed sampling and analysis programme of the lake water and sediments was implemented. Basic water quality, ionic and nutrient data gave no indication of any deterioration in the water quality of the lake, which was attributable to human usage in general or motorized recreational activities in particular. However, analysis of samples taken from the organic bottom sediments of the lake revealed the presence of 10 PAH, including benzo(a)pyrene, chrysene, fluoranthene, phenanthrene and pyrene, which are known to be indicative of fossil fuel combustion processes. Three PAH compounds were found at all survey sites: benzo(a)pyrene (in 46% of samples), fluoranthene (in 53% of samples) and pyrene (in 44% of samples). Results of the analyses were compared with values from published guidelines for residues in freshwaters and sediments, as well as with previous studies dealing with the effects of fossil fuel combustion products on lakes. The highest PAH concentrations in sediments were recorded for benzo(a)pyrene, with three values (830, 955 and 1070 ,g kg,1 dryweight) exceeding the upper threshold recommended in the draft Canadian freshwater sediment quality guidelines. Benzo(a)pyrene also exceeded the lower Canadian sediment threshold in 51 (40%) samples. These results indicate a significant level of chemical contamination of Brown Lake as a consequence of four decades of motorized recreational activities and present a significant risk to aquatic biota, particularly benthic and littoral invertebrates associated with the contaminated sediments. [source] Gas cooking, kitchen ventilation, and asthma, allergic symptoms and sensitization in young children , the PIAMA studyALLERGY, Issue 5 2006S. M. Willers Background:, Several studies reported inconsistent associations between using gas for cooking and respiratory symptoms or lung function in children. Kitchen ventilation characteristics may modify the relationship between gas cooking and respiratory health. The aim of this study was to investigate the effect of kitchen ventilation (while cooking) on the relationship between gas cooking, combustion product dispersal, and respiratory and allergic outcomes in children. Methods:, Data on respiratory and allergic symptoms and diagnoses were collected by yearly questionnaires in a population of over 3000 children participating in a birth cohort study on development of allergy and asthma. At 4 years of age, a sub-sample of 647 children provided blood samples for antibody testing. Data on gas cooking and kitchen ventilation were collected when the children were 5 years old. Based on these data a model was constructed to determine the chance of accumulation of combustion products (CACP) in the kitchen. Results:, No relationship was found between gas cooking and any of the respiratory or allergy outcomes except nasal symptoms. The overall results did not change when the ,CACP' was used as exposure variable instead, while the association for nasal symptoms decreased to borderline significance. Conclusion:, Our results suggest that gas cooking per se is associated with nasal symptoms in young children and not with the other respiratory symptoms that were investigated. Taking kitchen ventilation characteristics into account did not lead to different conclusions in this population where, according to the classification system, the majority of households using gas for cooking have insufficient kitchen ventilation. [source] WTC medical monitoring and treatment program: Comprehensive health care response in aftermath of disasterMOUNT SINAI JOURNAL OF MEDICINE: A JOURNAL OF PERSONALIZED AND TRANSLATIONAL MEDICINE, Issue 2 2008Jacqueline M. Moline MD Abstract The attack on the World Trade Center (WTC) on September 11th, 2001 exposed thousands of individuals to an unprecedented mix of chemicals, combustion products and micronized building materials. Clinicians at the Mount Sinai Irving Selikoff Center for Occupational and Environmental Medicine, in partnership with affected stakeholder organizations, developed a medical screening program to evaluate the health status of workers and volunteers who spent time at the WTC site and thus sustained exposure in the aftermath of September 11th. Standardized questionnaires were adapted for use in this unique population and all clinicians underwent training to ensure comparability. The WTC Worker and Volunteer Medical Screening Program (MSP) received federal funding in April 2002 and examinations began in July 2002. The MSP and the follow up medical monitoring program has successfully recruited nearly 22,000 responders, and serves as a model for the rapid development of a medical screening program to assess the health of populations exposed to environmental hazards as a result of natural and man-made disasters. The MSP constitutes a successful screening program for WTC responders. We discuss the challenges that confronted the program; the absence of a prior model for the rapid development of a program to evaluate results from mixed chemical exposures; little documentation of the size of the exposed population or of who might have been exposed; and uncertainty about both the nature and potential severity of immediate and long-term health effects. Mt Sinai J Med 75:67,75, 2008© 2008 Mount Sinai School of Medicine [source] The design of duct venting of gas explosionsPROCESS SAFETY PROGRESS, Issue 2 2008Almerinda Di Benedetto Abstract Venting systems are useful for the mitigation of accidental explosions. Vent ducts should be used if equipment is located indoors, as NFPA 68 (2007) suggests, for discharging combustion products to safe location. However, the presence of a duct is likely to increase the severity of the explosion with respect to simply vented vessels. Up to now, no reliable correlations are available for the sizing of ducted vented systems. The only correlation available was developed by Bartknecht in 1993 for gas explosion, also acknowledged by NFPA 68. In this study, we propose an engineering correlation based on semi-empirical engineering methodologies, which is able to quantify the relations between geometric properties and the peak pressure occurring in the combustion chamber in the presence of a duct fitted on the vent panel. To this aim, we have regressed all the available experimental data on gas explosion in ducted-vented vessels. © 2007 American Institute of Chemical Engineers Process Saf Prog, 2008 [source] Prediction of flammability speciation for the lower alkanes, carboxylic acids, and estersPROCESS SAFETY PROGRESS, Issue 1 2007M. Palucis Abstract A Gibbs energy minimization procedure is used to predict the flammability envelopes of alkanes, carboxylic acids, and acetates. In addition to providing the calculated adiabatic flame temperature (CAFT), the product profiles reveal regions of incomplete combustion products and the onset of methane formation above 0.0001 mole fraction. Temperatures at the predicted onset of methane production appear to be closely related to the temperature at the upper flammability limit (UFL). Although a fixed CAFT value could be related to the lower flammability limit (LFL), it was found that this was not the case with the UFL and only for acetic acid could a single CAFT value of 1200K be used to conservatively predict the flammable region. Rather, in general, a single CAFT value could not conservatively predict the upper flammable region. The predictions also reveal local maxima and minima in the concentrations of reaction products. These maps of incomplete combustion products for the flammability region predict that incomplete combustion products are produced at fuel/oxygen ratios significantly below the fuel/oxygen stoichiometric ratio. This region decreases as the limiting oxygen concentration is approached. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006 [source] Ways to Create New CHNO-Oxidizers for Stoichiometric Gas-Generating Compositions with Low Combustion TemperaturePROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 5 2007David Abstract The investigation is aimed to study the possibility of creation of new CHNO-oxidizers for smokeless gas-generating compositions for airbag inflators. For ensuring low amount of CO and nitrogen oxides in combustion products it is necessary to create stoichiometric compositions with a relatively low combustion temperature. Ways to create new oxidizers acceptable to this requirement are examined, mainly by introducing low-enthalpy oxygen-containing groups into the oxidizer molecule. Standard enthalpy of formation (,fH°) has been calculated for substances with unknown ,fH°, thermal stability has been qualitatively estimated, and combustion temperatures of stoichiometric compositions have been calculated. [source] Partitioning behavior of mercury during coal combustion: the influence of low-NOx burners and operation load of boilerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2009Guang-Qian Luo Abstract Two 200 MW, pulverized bituminous coal-fired electric utility boilers each equipped with a five-field cold-side electrostatic precipitator (ESP) as the only air pollution control device (APCD) were investigated on mercury distribution and speciation under various conditions. With the same fuel consumption, both facilities are the same but with different burners, low-NOx type and conventional type. Sampling points of gaseous mercury and chlorine species were at the inlet and outlet of the ESP. The mercury concentrations in various solids, including parent coal, bottom slag, economizer bottom ash and fly ash in different hoppers of ESP, were sampled and analyzed. The Ontario Hydro Method was employed to detect mercury in flue gas, and HCl and Cl2 were detected by the EPA method 26. A series of tests were conducted on the boiler with low-NOx burners under various loads (70, 85 and 100% of full load) and on the other boiler with conventional burners under full load. Results showed that small amount of mercury remained in the solid combustion products and most of mercury was released into the atmosphere. The majority of the released mercury was in oxidized form. Burner types and load variation had effects on Cl species concentration in flue gas. Furthermore, particle diameter and carbon content and specific surface area of fly ash affected speciation and distribution of mercury and mercury removal efficiency of ESP. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Production of biodiesel: possibilities and challengesBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 1 2007Sulaiman Al-Zuhair Abstract Biodiesel, defined as monoalkyl fatty acid ester (preferentially methyl and ethyl esters), represents a promising alternative fuel for use in compression-ignition (diesel) engines. Biodiesel fuel comes from renewable sources as it is plant- not petroleum-derived and as such it is biodegradable and less toxic. In addition, relative to conventional diesel, its combustion products have reduced levels of particulates, carbon oxides, sulphur oxides and, under some conditions, nitrogen oxides. Enzymatic production of biodiesel has been proposed to overcome the drawbacks of the conventional chemically catalyzed processes. The main obstacle facing full exploitation of the enzyme, lipase, potential is its cost. Therefore, reuse of lipase is essential from the economic point of view, which can be achieved by using the lipase in immobilized form. In addition, immobilized lipase displays improved stability and activity. Common immobilization techniques include attachment to solid supports and entrapment within the matrix of a polymer. This article presents a comparison between conventional processes and enzymatic processes and different possible feedstocks for biodiesel production. In addition, possible ways to overcome the problems facing the use of lipase are described. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd [source] | |||||||||||||