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Sample records for flame coal density

  1. Effect of multiphase radiation on coal combustion in a pulverized coal jet flame

    Science.gov (United States)

    Wu, Bifen; Roy, Somesh P.; Zhao, Xinyu; Modest, Michael F.

    2017-08-01

    The accurate modeling of coal combustion requires detailed radiative heat transfer models for both gaseous combustion products and solid coal particles. A multiphase Monte Carlo ray tracing (MCRT) radiation solver is developed in this work to simulate a laboratory-scale pulverized coal flame. The MCRT solver considers radiative interactions between coal particles and three major combustion products (CO2, H2O, and CO). A line-by-line spectral database for the gas phase and a size-dependent nongray correlation for the solid phase are employed to account for the nongray effects. The flame structure is significantly altered by considering nongray radiation and the lift-off height of the flame increases by approximately 35%, compared to the simulation without radiation. Radiation is also found to affect the evolution of coal particles considerably as it takes over as the dominant mode of heat transfer for medium-to-large coal particles downstream of the flame. To investigate the respective effects of spectral models for the gas and solid phases, a Planck-mean-based gray gas model and a size-independent gray particle model are applied in a frozen-field analysis of a steady-state snapshot of the flame. The gray gas approximation considerably underestimates the radiative source terms for both the gas phase and the solid phase. The gray coal approximation also leads to under-prediction of the particle emission and absorption. However, the level of under-prediction is not as significant as that resulting from the employment of the gray gas model. Finally, the effect of the spectral property of ash on radiation is also investigated and found to be insignificant for the present target flame.

  2. Sulfur release from Ohio coals and sorbent kinetics in pulverized coal flames. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Essenhigh, R. [Ohio State Univ., Columbus, OH (United States). Robinson Lab.

    1992-08-01

    In this report we describe the results of investigations into the structure of combustion and sulfur release profiles from coal burning in One-Dimensional P.C. flames using a furnace of unique design for the measurements. Selected measurements were also-carried out in a special high-intensity furnace also of unique design. The formal project work started in late Fall 1989, with unfunded preliminary work in the months prior to that. The process of limestone injection into the flame to control sulfur oxides emissions is a long-standing concept that has been given particular formulation in the LIMB process, and studies of such systems provide bases for commercial system economics. Problems with LIMB and related systems indicated need for better understanding of, jointly, the sulfur release from the coal and the sorbent behavior by the limestone. The investigations as reported in Vol. 1 of this Report used 14 different coals under a range of different initial and operating conditions, and the resulting measurements have provided a database of major proportions, as tabulated in the attached Volumes 2, 3, 4, 5, 6, and 7 of this report. This database consists of sets of measurements totalling about 45,000 entries for all independent and dependent parameters involved. The independent parameters included: coal type (analysis), firing rate, stoichiometry (fuel/air ratio), and sorbent content of the

  3. A chemical engineering model for predicting NO emissions and burnout from pulverised coal flames

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, L.S.; Glarborg, P.; Dam-Johansen, K.; Hepburn, P.W.; Hesselmann, G. [Technical University of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering

    1998-07-01

    This work is concerned with the applicability of modelling swirling pulverised coal flames with ideal chemical reactors. The objectives were to predict the emissions of NO and CO, and the burnout of char. The fluid dynamics were simplified by use of a system of ideal chemical reactors. The near burner zone was modelled as a well-stirred reactor, the jet expansion as a plug flow reactor, the external recirculation zone as a well-stirred reactor, and the down stream zone as a number of well-stirred reactors in series. A reduced model of a detailed reaction mechanism was applied to model gas phase chemistry and a novel model was developed for soot oxidation. A population balance was used to keep track of size and density changes for the char combustion. Individual particle temperatures were calculated for each size fraction. The model includes only one burner specific calibration parameter which is related to the mixing of air and fuel. The model was validated against experimental results from a 160 kH{sub th} pulverised coal burner. For single staged combustion at varying stoichiometries, for two stage combustion, and for different coals good agreement between model and experiment was obtained for NO emissions and carbon in ash. This work also indicates that the interaction between the homogeneous gas phase chemistry and the heterogeneous chemistry (soot and char), due to recombination of radicals on the surfaces, is of importance for the nitrogen chemistry in coal flames, especially for ammonia formation. 84 refs., 31 figs., 7 tabs.

  4. The Influence of Flame Retardant Treated Timber Density on Combustibility

    Directory of Open Access Journals (Sweden)

    Zbignev Karpovič

    2011-04-01

    Full Text Available Timber is widely used as a construction material in the majority of countries. In most cases, timber is the main structural material. Timber and timber fabrics used in building structure elements have to fulfill the requirements of fire safety. This article presents factors affecting the combustibility of timber, mainly the influence of flame retardants on the combustion phase, timber density and moisture. The influence of flame retardant treated timber density on combustibility is analyzed in this paper. Research was performed according to the requirements of the standard LST ISO 5657:1999 “Reaction to fire tests – ignitibility of building products using a radiant heat source”. The influence of flame retardant treated timber density on combustibility is assessed according to duration up to the combustion of the specimen. Article in Lithuanian

  5. Comparative study of semi-industrial-scale flames of pulverized coals and biomass

    Energy Technology Data Exchange (ETDEWEB)

    Ballester, J.; Barroso, J.; Cerecedo, L.M.; Ichaso, R. [University of Zaragoza, Zaragoza (Spain)

    2005-05-01

    Three p.f. flames have been studied in a semi-industrial furnace, using different fuels: a bituminous coal, a lignite, and a biomass (oak sawdust). The operating conditions were exactly the same for the two coals, and very similar to those for the biornass flame. The objective was to evaluate the impact of differences in fuel composition on flame characteristics, through measurement of the spatial distribution of the main parameters: temperature and concentrations of O{sub 2}, CO, NOx, unburnt hydrocarbons, and N{sub 2}O. The higher volatiles content in the lignite leads to higher temperatures and more intense combustion than the bituminous coal. Nevertheless, as might be expected, more marked differences are observed between the flames from the biomass and coals. The much higher volatiles content of the wood results in a more intense flame close to the burner, as indicated by visual observations and by concentrations of unburnt gases (CO and unburnt hydrocarbons) in that zone. It is remarkable that the combustion zone extends further for the biomass; while unburnt species were very low for the coals at an axial distance of 1 m, high values were detected for the pulverized oak. The measurements suggest that two stages can be distinguished in the biomass flame: a zone of intense combustion close to the burner, followed by a second region where the large biomass particles gradually devolatilize and are consumed.

  6. Measurement method and experimental research on flame emissivity in Coal-fired furnaces

    Institute of Scientific and Technical Information of China (English)

    YANG Chao; LOU Chun; JIANG Zhi-wei; ZHOU Huai-chun

    2007-01-01

    The combustion condition in coal-fired furnaces of the large power station boiler is very complex and the flame emissivity is one of the important combustion parameters.A measurement method of the flame emissivity based on the blackbody furnace calibration of CCD(Charge Coupled Device)cameras and the color image processing techniques of computer was introduced.The experimentaI research on the flame emissivity in a 200 MW boiler furnace and a 300 MW boiler furnace was conducted respectively through the several CCD cameras installed at different height in furnace.The measurement results show:the flame emissivity increases with the increase of the unit load.the flame emissivity of the burner areas in furnace is the highest and the flame emissivity decrease with the increase of height of furnace above the burners area.

  7. On-line tracking of pulverized coal and biomass fuels through flame spectrum analysis

    Institute of Scientific and Technical Information of China (English)

    迟天阳; 张宏建

    2007-01-01

    This paper presents a new approach to the on-line tracking of pulverized coal and biomass fuels through flame spectrum analysis. A flame detector containing four photodiodes is used to derive multiple signals covering a wide spectrum of the flame from visible, near-infrared and mid-infrared spectral bands as well as a part of far-infrared band. Different features are extracted in time and frequency domains to identify the dynamic "fingerprints" of the flame. Fuzzy logic inference techniques are employed to combine typical features together and infer the type of fuel being burnt. Four types of pulverized coal and five types of biomass are burnt on a laboratory-scale combustion test rig. Results obtained demonstrate that this approach is capable of tracking the type of fuel under steady combustion conditions.

  8. Inhibition Effect of Phosphorus Flame Retardants on the Fire Disasters Induced by Spontaneous Combustion of Coal

    Directory of Open Access Journals (Sweden)

    Yibo Tang

    2017-01-01

    Full Text Available Coal spontaneous combustion (CSC generally induces fire disasters in underground mines, thus causing serious casualties, environmental pollution, and property loss around the world. By using six P-containing additives to process three typical coal samples, this study investigated the variations of the self-ignition characteristics of the coal samples before and after treatment. The analysis was performed by combining thermogravimetric analysis/differential scanning calorimetry (TG/DSC Fourier transform infrared spectrometer (FTIR and low temperature oxidation. Experimental results showed that P-containing inhibitors could effectively restrain the heat emitted in the combustion of coal samples and therefore the ignition temperature of the coal samples was delayed at varying degrees. The combustion rate of the coal samples was reduced as well. At the temperatures ranging from 50°C to 150°C, the activation energy of the coal samples after the treatment was found to increase, which indicated that the coal samples were more difficult to be oxidized. After being treated with phosphorus flame retardants (PFRs, the content of several active groups represented by the C-O structure in the three coal samples was proved to be obviously changed. This suggested that PFRs could significantly inhibit the content of CO generated by the low temperature oxidation of coal, and the flame-retardant efficiency grew with the increasing temperature. At 200°C, the maximal inhibition efficiency reached approximately 85%.

  9. Flat-flame burner studies of pulverized-coal combustion. Experimental results on char reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Peck, R.E.; Shi, L.

    1996-12-01

    Structure of laminar, premixed pulverized-coal flames in a 1-D reactor has been studied with emphasis on char reactivity. A 1.1-meter-long tube furnace accommodated high-temperature environments and long residence times for the laminar flames produced by a flat-flame, coal-dust burner. Experiments were conducted at different operating conditions (fuel type/size, fuel-air ratio). Measurements included solid sample composition, major gas species and hydrocarbon species concentrations, and gas- and particle-phase line-of-sight temperatures at different axial locations in flames. Degree of char burnout increased with coal volatiles content and decreased with coal particle size. Combustion in furnace was in oxidizer-deficient environment and higher burnout was achieved as the fuel-air ratio neared stoichiometric. For 0-45 {mu}m particles most of the fixed carbon mass loss occurred within 5 cm of the furnace inlet, and char reaction was slow downstream due to low oxidizer concentrations. Fixed carbon consumption of the 45-90 {mu}m particles generally was slower than for the small particles. About 40%-80% of the fixed carbon was oxidized in the furnace. Primary volatiles mass loss occurred within the first 4.5 cm, and more than 90% of the volatiles were consumed in the flames. The flames stabilized in the furnace produced less CH{sub 4} and H{sub 2} in the burnt gas than similar unconfined flames. NO concentrations were found to decrease along the furnace and to increase with decreasing fuel/air ratio. Temperature measurement results showed that gas-phase temperatures were higher than solid-phase temperatures. Temperatures generally decreased with decreasing volatiles content and increased as the equivalence ratio approached one. The results can be used to interpret thermochemical processes occurring in pulverized-coal combustion. (au) 15 refs.

  10. Measurement and Modeling of Particle Radiation in Coal Flames

    DEFF Research Database (Denmark)

    Bäckström, Daniel; Johansson, Robert; Andersson, Klas Jerker

    2014-01-01

    This work aims at developing a methodology that can provide information of in-flame particle radiation in industrial-scale flames. The method is based on a combination of experimental and modeling work. The experiments have been performed in the high-temperature zone of a 77 kWth swirling lignite...... properties. The in-flame particle radiation was measured with a Fourier transform infrared (FTIR) spectrometer connected to a water-cooled probe via fiber optics. In the cross-section of the flame investigated, the particles were found to be the dominating source of radiation. Apart from giving information...

  11. Large eddy simulations of coal jet flame ignition using the direct quadrature method of moments

    Science.gov (United States)

    Pedel, Julien

    The Direct Quadrature Method of Moments (DQMOM) was implemented in the Large Eddy Simulation (LES) tool ARCHES to model coal particles. LES coupled with DQMOM was first applied to nonreacting particle-laden turbulent jets. Simulation results were compared to experimental data and accurately modeled a wide range of particle behaviors, such as particle jet waviness, spreading, break up, particle clustering and segregation, in different configurations. Simulations also accurately predicted the mean axial velocity along the centerline for both the gas phase and the solid phase, thus demonstrating the validity of the approach to model particles in turbulent flows. LES was then applied to the prediction of pulverized coal flame ignition. The stability of an oxy-coal flame as a function of changing primary gas composition (CO2 and O2) was first investigated. Flame stability was measured using optical measurements of the flame standoff distance in a 40 kW pilot facility. Large Eddy Simulations (LES) of the facility provided valuable insight into the experimentally observed data and the importance of factors such as heterogeneous reactions, radiation or wall temperature. The effects of three parameters on the flame stand-off distance were studied and simulation predictions were compared to experimental data using the data collaboration method. An additional validation study of the ARCHES LES tool was then performed on an air-fired pulverized coal jet flame ignited by a preheated gas flow. The simulation results were compared qualitatively and quantitatively to experimental observations for different inlet stoichiometric ratios. LES simulations were able to capture the various combustion regimes observed during flame ignition and to accurately model the flame stand-off distance sensitivity to the stoichiometric ratio. Gas temperature and coal burnout predictions were also examined and showed good agreement with experimental data. Overall, this research shows that high

  12. Numerical simulation of excess-enthalpy combustion flame propagation of coal mine methane in ceramic foam

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the assumption of a local non-equilibrium of heat transfer between a solid matrix and gas,a mathematic model of coal mine methane combustion in a porous medium was established,as well the solid-gas boundary conditions.We simulated numerically the flame propagation characteristics.The results show that the flame velocity in ceramic foam is higher than that of free laminar flows;the maximum flame velocity depends on the combined effects of a radiation extinction coefficient and convection heat transf...

  13. Prediction of Excess Air Factor in Automatic Feed Coal Burners by Processing of Flame Images

    Science.gov (United States)

    Talu, Muhammed Fatih; Onat, Cem; Daskin, Mahmut

    2017-05-01

    In this study, the relationship between the visual information gathered from the flame images and the excess air factor λ in coal burners is investigated. In conventional coal burners the excess air factor λ. can be obtained using very expensive air measurement instruments. The proposed method to predict λ for a specific time in the coal burners consists of three distinct and consecutive stages; a) online flame images acquisition using a CCD camera, b) extraction meaningful information (flame intensity and brightness)from flame images, and c) learning these information (image features) with ANNs and estimate λ. Six different feature extraction methods have been used: CDF of Blue Channel, Co-Occurrence Matrix, L ∞-Frobenius Norms, Radiant Energy Signal (RES), PCA and Wavelet. When compared prediction results, it has seen that the use of co-occurrence matrix with ANNs has the best performance (RMSE = 0.07) in terms of accuracy. The results show that the proposed predicting system using flame images can be preferred instead of using expensive devices to measure excess air factor in during combustion.

  14. Study of flame combustion of off-design binary coal blends in steam boilers

    Science.gov (United States)

    Kapustyanskii, A. A.

    2017-07-01

    Changes in the structure of the fuel consumption by the thermal power stations of Ukraine caused by failure in supplying anthracite from the Donets Basin are analyzed and the major tasks of maintaining the functioning of the coal industry are formulated. The possibility of using, in the near future, the flame combustion of off-design solid fuels in the power boilers of the thermal power plants and combined heat and power plants is studied. The article presents results of expert tests of the TPP-210A and TP-15 boilers under flame combustion of mixtures of anthracites, lean coal, and the coal from the RSA in various combinations. When combusting, such mixtures have higher values of the combustibles yield and the ash fusibility temperature. The existence of the synergetic effect in the flame combustion of binary coal blends with different degrees of metamorphism is discussed. A number of top-priority measures have been worked out that allow for switching over the boilers designed to be fired with anthracite to using blends of coals of different ranks. Zoned thermal analysis of the TP-15 boiler furnace was performed for numerical investigation of the temperature distribution between the furnace chamber zones and exploration of the possibility of the liquid slag disposal and the temperature conditions for realization of this process. A positive result was achieved by combusting anthracite culm (AC), the coal from the RSA, and their mixtures with lean coal within the entire range of the working loads of the boilers in question. The problems of normalization of the liquid slag flow were also successfully solved without closing the slag notch. The results obtained by balance experiments suggest that the characteristics of the flame combustion of a binary blend, i.e., the temperature conditions in the furnace, the support flame values, and the degree of the fuel burnout, are similar to the characteristics of the flame of the coal with a higher reactive capacity, which

  15. Mathematical modelling of flue gas tempered flames produced from pulverised coal fired with oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Breussin, A.; Weber, R.; Kamp, W.L. van de

    1997-10-01

    The combustion of pulverised coal in conventional utility boilers contributes significantly to global CO{sub 2} emissions. Because atmospheric air is used as the combustion medium, the exhaust gases of conventional pulverised coal fired utility boilers contain approximately 15 % CO{sub 2}. This relatively low concentration makes separating and recovering CO{sub 2} a very energy-intensive process. This process can be simplified if N{sub 2} is eliminated from the comburent before combustion by firing the pulverised coal with pure oxygen. However, this concept will result in very high flames temperatures. Flue gas recirculation can be used to moderate the flame temperature, whilst generating a flue gas with a CO{sub 2} concentration of 95 %. In this presentation, both experimental and modelling work will be described. The former deals with identifying the issues related to the combustion of pulverised coal in simulated turbine exhaust gas, particularly with respect to stability, burnout and pollutant emissions. The second part of this presentation describes mathematical modelling of type 2 as well as type 1 swirling pulverised coal flames. Future work will concentrate on high CO{sub 2} levels environments. (orig.)

  16. Combustion characteristics of pulverized coal and air/gas premixed flame in a double swirl combustor

    Energy Technology Data Exchange (ETDEWEB)

    Kamal, M.M. [Ain Shams University, Cairo (Egypt). Faculty of Education

    2009-07-01

    An experimental work was performed to investigate the co-firing of pulverized coal and premixed gas/air streams in a double swirl combustor. The results showed that the NOx emissions are affected by the relative rates of thermal NOx formation and destruction via the pyrolysis of the fuel-N species in high temperature fuel-rich zones. Various burner designs were tested in order to vary the temperature history and the residence time across both coal and gas flames inside the furnace. It was found that by injecting the coal with a gas/air mixture as a combined central jet surrounded by a swirled air stream, a double flame envelope develops with high temperature fuel-rich conditions in between the two reaction zones such that the pyrolysis reactions to N{sub 2} are accelerated. A further reduction in the minimum NOx emissions, as well as in the minimum CO concentrations, was reported for the case where the coal particles are fed with the gas/air mixture in the region between the two swirled air streams. On the other hand, allocating the gas/air mixture around the swirled air-coal combustion zone provides an earlier contact with air and retards the NOx reduction mechanism in such a way that the elevated temperatures around the coal particles allow higher overall NOx emissions. The downstream impingement of opposing air jets was found more efficient than the impinging of particle non-laden premixed flames for effective NOx reduction. In both cases, there is an upstream flow from the stagnation region to the coal primary combustion region, but with the case of air impingement, the hot fuel-rich zone develops earlier. The optimum configuration was found by impinging all jets of air and coal-gas/air mixtures that pronounced minimum NOx and CO concentrations of 310 and 480ppm, respectively.

  17. Towards a better understanding of biomass suspension co-firing impacts via investigating a coal flame and a biomass flame in a swirl-stabilized burner flow reactor under same conditions

    DEFF Research Database (Denmark)

    Yin, Chungen; Rosendahl, Lasse; Kær, Søren Knudsen

    2012-01-01

    This paper investigates the combustion characteristics of firing pure coal and firing pure wheat straw in a 150 kW swirl-stabilized burner flow reactor under nearly same conditions. The results indicate very different combustion characteristics between the coal flame and straw flame. In the straw...... flame, the straw particles are little affected by the swirling secondary air jet and travel in a nearly straight line through the oxygenlean core zones. In the coal flame, most of the coal particles are strongly affected by the secondary air jet and swirled into the oxygen-rich outer radius, which also...

  18. Techniques to determine ignition, flame stability and burnout of blended coals in p.f. power station boilers

    Energy Technology Data Exchange (ETDEWEB)

    Su, S.; Pohl, J.H.; Holcombe, D.; Hart, J.A. [University of Queensland, Brisbane, Qld. (Australia). Dept. of Chemical Engineering

    2001-07-01

    The blending of coals has become popular to improve the performance of coals, to meet specifications of power plants and to reduce the cost of coals. This article reviews the results and provides new information on ignition, flame stability, and carbon burnout studies of blended coals. The reviewed studies were conducted in laboratory-, pilot-, and full-scale facilities. The new information was taken in pilot-scale studies. The results generally show that blending a high-volatile coal with a low-volatile coal or anthracite can improve the ignition, flame stability and burnout of the blends. This paper discusses two general methods to predict the performance of blended coals: (1) experiment; and (2) indices. Laboratory- and pilot-scale tests, at least, provide a relative ranking of the combustion performance of coal/blends in power station boilers. Several indices, volatile matter content, heating value and a maceral index, can be used to predict the relative ranking of ignitability and flame stability of coals and blends. The maceral index, fuel ratio, and vitrinite reflectance can also be used to predict the absolute carbon burnout of coal and blends within limits. 59 refs., 20 figs., 4 tabs.

  19. The effect of fuel stream mixing on the performance of pulverised coal flames

    Energy Technology Data Exchange (ETDEWEB)

    Lockwood, F.C.; Diedrichsen, J.; Kandamby, N.; Costen, P.; Abbas, T. [Imperial College of Science, Technology and Medicine, London (United Kingdom). Mechanical Engineering Dept.

    1998-12-31

    A programme of research, integrating experimental investigations undertaken in a large laboratory scale furnace with the development of mathematical modelling techniques has been performed in order to determine the effect of fuel and air stream mixing on the performance of atmospheric pulverised coal combustion, with reference to utility fired boilers. Several mixing configurations have been investigated, namely, the mixing of the fuel streams prior to injection (static blending), within the flame (dynamic blending) and in the combustion zone (reburn). During the blending exercise, in collaboration with International Combustion Limited, Derby, two world-traded coals (a Rand variety of coal from South Africa and Shamrock from the USA) have been premixed prior to being fired. A set of comparative data for flame performance and NO{sub x} emissions for identical blend ratios has been established for both in the large scale laboratory rated at 150 kW in London and at 38 MW scale in the combustion test rig at ICL, Derby. The blending exercise was continued through dynamic blending experiments in which two independent coal feeders and conduits have been incorporated into the existing system so that the initial mixing of the two fuels takes place at the burner exit. Using the same blending ratios as in the static blending trials, an assessment has been made of the effect of injection location of each of the fuels to determine the conditions which result in the lowest NO{sub x} levels while maintaining the broadest flame stability limits. 11 refs., 18 figs., 8 tabs.

  20. The effect of scaling on the performance of coal flames

    Energy Technology Data Exchange (ETDEWEB)

    Lymberopoulos, N. [CINAR sa, Athens (Greece)

    1998-12-31

    In large process industries such as utility boilers used for the generation of steam to produce electricity, cement kilns, glass tanks etc. the collection of experimental data is often difficult, time consuming and expensive. Operators are reluctant to interfere with the running of a process in order to undertake the parametric exercises necessary to provide the information necessary to establish performance trends. The information that may be gathered, is not necessarily universal, applying only to the unit on which it was recorded, while the constancy of the various parameters may be suspect. One alternative is the use of scale versions of the prototype in which the physical reactions are well replicated. Such small scale units can provide total, immediate and accurate control over the inlet parameters and are easily accessible in regard to obtaining the necessary information such as gas species concentrations, temperatures and combustion efficiency data throughout the flame and the furnace. These units are also invaluable in the derivation and subsequent appraisal of novel techniques. The art is how small scale observations can be interpreted in the large scale. This is where mathematical modelling techniques are employed. What changes have to be accommodated in the model as the scale is increased? In particular what changes occur in the prediction of combustion performance of a 150 kW furnace and a 35 MW one and what justifiable modifications can be made to accommodate these nuances so that predictions at full scale can be made with added confidence. This was studied. 12 refs., 9 figs., 4 tabs.

  1. Silicon production using long flaming coal and improvement of its quality indicators

    Directory of Open Access Journals (Sweden)

    A. D. Mekhtiev

    2014-10-01

    Full Text Available The object of this study is to explore possibility of metallothermic producing of crystalline silicon using various types of carbon reducing agents as a reducing agent. The experience of existing enterprises shows that one of the best carbon reducing agents qualifying silicon electric melting technology is charcoal. On the other hand, charcoal has a number of disadvantages, such as its scarcity, high cost and low mechanical strength. Experimental melts has shown the principal possibility of producing the crystalline silicon that meets the requirements of quartz standard using low ash special coke and long-flame coal as reducing agents.

  2. Scalar filtered mass density functions in nonpremixed turbulent jet flames

    Energy Technology Data Exchange (ETDEWEB)

    Drozda, Tomasz G.; Wang, Guanghua; Sankaran, Vaidyanathan; Mayo, Jackson R.; Oefelein, Joseph C.; Barlow, Robert S. [Combustion Research Facility, Sandia National Laboratories, P.O. Box 969, MS 9051, Livermore, CA 94551 (United States)

    2008-10-15

    Filtered mass density functions (FMDFs) of mixture fraction and temperature are studied by analyzing experimental data obtained from one-dimensional Raman/Rayleigh/LIF measurements of nonpremixed CH{sub 4}/H{sub 2}/N{sub 2} turbulent jet flames at Reynolds numbers of 15,200 and 22,800 (DLR-A and -B). The experimentally determined FMDFs are conditioned on the Favre filtered values of the mixture fraction and its variance. Filter widths are selected as fixed multiples of the experimentally determined dissipation length scale at each measurement location. One-dimensional filtering using a top-hat filter is performed to obtain the filtered variables used for conditioning. The FMDFs are obtained by binning the mass and filter kernel weighted samples. Emphasis is placed on the shapes of the FMDFs in the fuel-rich, fuel-lean, and stoichiometric intervals for the Favre filtered mixture fraction, and low, medium, and high values for the Favre filtered mixture fraction variance. It is found that the FMDFs of mixture fraction are unimodal in samples with low mixture fraction variance and bimodal in samples with high variance. However, the FMDFs of mixture fraction at the smallest filter size studied are unimodal for all values of the variance. The FMDFs of temperature are unimodal in samples with low mixture fraction variance, and either unimodal or bimodal, depending on the mixture fraction mean, in samples with high variance. The influence of the filter size and the jet Reynolds number on the FMDFs is also considered. (author)

  3. Measurements of density field in a swirling flame by 2D spontaneous Raman scattering

    Science.gov (United States)

    Sharaborin, D. K.; Dulin, V. M.; Lobasov, A. S.; Markovich, D. M.

    2016-10-01

    This paper presents an evaluation of the density distribution in swirling turbulent premixed flames. The measurement principle is based on registration of spontaneous Raman scattering, when the reacting gas flow is illuminated by a laser sheet. Evaluation of 1D and 2D distributions of density and temperature were performed in a laminar Bunsen flame as a test case for validation of experimental technique. Time-averaged 2D images of the scattering during rovibronic transitions of nitrogen molecules were captured in turbulent premixed low-swirl and high-swirl (Re = 5000) propane-air flames in a wide range of equivalence ratio. The obtained density fields are useful for better understanding of heat and mass transfer in swirl-stabilized turbulent flames and for validation of CFD results.

  4. The Mechanisms of Flame Stabilization and Low NOx Emission in an Eccentric Jet Pulverized Coal Combustor

    Institute of Scientific and Technical Information of China (English)

    SunWenchao; SunYezhu; 等

    1992-01-01

    The mechanisms of flame stabilization and low NOx emission features of an accentric jet pulverzed coal combustor were studied through numerical modelling and experimental investigation.The results show that the formation of the unique flowfield structure is closely related to the interaction among combustor configuration.the primary jet and the control Jet.and that certain rules should be follwed in orber to obtain the optimum condition for flame stabilization.The distributions of temperature and concentration of NO,O2,CO and CO2 inside the combustor were experimentally measured.The effects of strustural and operational parameters on combustion and NO formation were studied.It was found that reduction of primary air,suitable use of control jet and reasonable uptilt angle of the primary jet all contributed to the reduction of NOx at the combustor exit.A new hypothesis,that reasonable separation of oxygen and fuel within the fuel-rich zone is beneficial to further reduction of NOx emission,is given,The study showed that good compatibility existed between the capability of flame stabilization and low NOX emission for this type of combustor.

  5. Methane Bubble Flame Tower--A Spectacularly Engaging Way to Teach Density

    Science.gov (United States)

    Sandoval, Christopher

    2012-01-01

    This article presents a demonstration using methane bubble flame tower that offers a fun and relatively cheap way of demonstrating what happens when there is a density difference. Teachers can do this as a predict-observe-explain demonstration after the students have learned about density to extend their learning and get into some higher order…

  6. The effect of hard coal density on its flotation performance

    Directory of Open Access Journals (Sweden)

    Ewa Małysa

    2005-11-01

    Full Text Available Hard coal flotation depends on many factors, one of which is the density of the grains floated. The heavier the grain, the greater the gravitational force that counteracts the force of adhesion between the grain and an air bubble, and the lower the probability of forming the grain-air bubble aggregate. This paper presents the results of a study on the effect of grain density on hard coal flotation. To eliminate the effect of grain size, densimetric fractions of very similar grain sizes were floated. Significant differences in the floatability of grains of the same size but of different densities were found. The floatability of coal grains dramatically decreased with their density

  7. Emission of volatile organic compounds from domestic coal stove with the actual alternation of flaming and smoldering combustion processes.

    Science.gov (United States)

    Liu, Chengtang; Zhang, Chenglong; Mu, Yujing; Liu, Junfeng; Zhang, Yuanyuan

    2017-02-01

    Volatile organic compounds (VOCs) emissions from the chimney of a prevailing domestic stove fuelled with raw bituminous coal were measured under flaming and smoldering combustion processes in a farmer's house. The results indicated that the concentrations of VOCs quickly increased after the coal loading and achieved their peak values in a few minutes. The peak concentrations of the VOCs under the smoldering combustion process were significantly higher than those under the flaming combustion process. Alkanes accounted for the largest proportion (43.05%) under the smoldering combustion, followed by aromatics (28.86%), alkenes (21.91%), carbonyls (5.81%) and acetylene (0.37%). The emission factors of the total VOCs under the smoldering combustion processes (5402.9 ± 2031.8 mg kg(-1)) were nearly one order of magnitude greater than those under the flaming combustion processes (559.2 ± 385.9 mg kg(-1)). Based on the VOCs emission factors obtained in this study and the regional domestic coal consumption, the total VOCs emissions from domestic coal stoves was roughly estimated to be 1.25 × 10(8) kg a(-1) in the Beijing-Tianjin-Hebei region. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Stretch rate effects and flame surface densities in premixed turbulent combustion up to 1.25 MPa

    KAUST Repository

    Bagdanavicius, Audrius

    2015-11-01

    Independent research at two centres using a burner and an explosion bomb has revealed important aspects of turbulent premixed flame structure. Measurements at pressures and temperatures up to 1.25MPa and 673K in the two rigs were aimed at quantifying the influences of flame stretch rate and strain rate Markstein number, Masr , on both turbulent burning velocity and flame surface density. That on burning velocity is expressed through the stretch rate factor, Io , or probability of burning, Pb 0.5. These depend on Masr , but they grow in importance as the Karlovitz stretch factor, K, increases, and are evaluated from the associated burning velocity data. Planar laser tomography was employed to identify contours of reaction progress variable in both rigs. These enabled both an appropriate flame front for the measurement of the turbulent burning velocity to be identified, and flame surface densities, with the associated factors, to be evaluated. In the explosion measurements, these parameters were derived also from the flame surface area, the derived Pb 0.5 factor and the measured turbulent burning velocities. In the burner measurement they were calculated directly from the flame surface density, which was derived from the flame contours.A new overall correlation is derived for the Pb 0.5 factor, in terms of Masr at different K and this is discussed in the light of previous theoretical studies. The wrinkled flame surface area normalised by the area associated with the turbulent burning velocity measurement, and the ratio of turbulent to laminar burning velocity, ut /ul , are also evaluated. The higher the value of Pb0.5, the more effective is an increased flame wrinkling in increasing ut /ul A correlation of the product of k and the laminar flame thickness with Karlovitz stretch factor and Markstein number is explored using the present data and those

  9. Fuel density effect on near nozzle flow field in small laminar coflow diffusion flames

    KAUST Repository

    Xiong, Yuan

    2015-01-01

    Flow characteristics in small coflow diffusion flames were investigated with a particular focus on the near-nozzle region and on the buoyancy force exerted on fuels with densities lighter and heavier than air (methane, ethylene, propane, and n-butane). The flow-fields were visualized through the trajectories of seed particles. The particle image velocimetry technique was also adopted for quantitative velocity field measurements. The results showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle, emphasizing the importance of the relative density of the fuel to that of the air on the flow-field. Nozzle heating influenced the near-nozzle flow-field particularly among lighter fuels (methane and ethylene). Numerical simulations were also conducted, focusing specifically on the effect of specifying inlet boundary conditions for fuel. The results showed that a fuel inlet boundary with a fully developed velocity profile for cases with long tubes should be specified inside the fuel tube to permit satisfactory prediction of the flow-field. The calculated temperature fields also indicated the importance of the selection of the location of the inlet boundary, especially in testing various combustion models that include soot in small coflow diffusion flames. © 2014 The Combustion Institute.

  10. Low Density Dry Coal Beneficiation Using an Air Dense Medium Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    LUO Zhen-fu; ZHU Jian-feng; FAN Mao-ming; ZHAO Yue-min; TAO Xiu-xiang

    2007-01-01

    For the production of low ash content clean coal, separation at low density is required for some raw coals. Based on analyzing the fluidizing characteristics of magnetic pearls with a specific size distribution and formation mechanism of a microbubble fluidized bed, optimal technological and operating parameters suitable for low density coal separation were determined. The experimental results show that an air dense medium fluidized bed with low density can be formed using magnetic pearls as medium solids, which can efficiently beneficiate coal of 6-50 mm size with a probable error Ep value of 0.05 at a separating density of 1.44 g/cm3.

  11. A Priori Assessment of Algebraic Flame Surface Density Models in the Context of Large Eddy Simulation for Nonunity Lewis Number Flames in the Thin Reaction Zones Regime

    Directory of Open Access Journals (Sweden)

    Mohit Katragadda

    2012-01-01

    Full Text Available The performance of algebraic flame surface density (FSD models has been assessed for flames with nonunity Lewis number (Le in the thin reaction zones regime, using a direct numerical simulation (DNS database of freely propagating turbulent premixed flames with Le ranging from 0.34 to 1.2. The focus is on algebraic FSD models based on a power-law approach, and the effects of Lewis number on the fractal dimension D and inner cut-off scale ηi have been studied in detail. It has been found that D is strongly affected by Lewis number and increases significantly with decreasing Le. By contrast, ηi remains close to the laminar flame thermal thickness for all values of Le considered here. A parameterisation of D is proposed such that the effects of Lewis number are explicitly accounted for. The new parameterisation is used to propose a new algebraic model for FSD. The performance of the new model is assessed with respect to results for the generalised FSD obtained from explicitly LES-filtered DNS data. It has been found that the performance of the most existing models deteriorates with decreasing Lewis number, while the newly proposed model is found to perform as well or better than the most existing algebraic models for FSD.

  12. Distribution of trace elements in selected pulverized coals as a function of particle size and density

    Science.gov (United States)

    Senior, C.L.; Zeng, T.; Che, J.; Ames, M.R.; Sarofim, A.F.; Olmez, I.; Huggins, Frank E.; Shah, N.; Huffman, G.P.; Kolker, A.; Mroczkowski, S.; Palmer, C.; Finkelman, R.

    2000-01-01

    Trace elements in coal have diverse modes of occurrence that will greatly influence their behavior in many coal utilization processes. Mode of occurrence is important in determining the partitioning during coal cleaning by conventional processes, the susceptibility to oxidation upon exposure to air, as well as the changes in physical properties upon heating. In this study, three complementary methods were used to determine the concentrations and chemical states of trace elements in pulverized samples of four US coals: Pittsburgh, Illinois No. 6, Elkhorn and Hazard, and Wyodak coals. Neutron Activation Analysis (NAA) was used to measure the absolute concentration of elements in the parent coals and in the size- and density-fractionated samples. Chemical leaching and X-ray absorption fine structure (XAFS) spectroscopy were used to provide information on the form of occurrence of an element in the parent coals. The composition differences between size-segregated coal samples of different density mainly reflect the large density difference between minerals, especially pyrite, and the organic portion of the coal. The heavy density fractions are therefore enriched in pyrite and the elements associated with pyrite, as also shown by the leaching and XAFS methods. Nearly all the As is associated with pyrite in the three bituminous coals studied. The sub-bituminous coal has a very low content of pyrite and arsenic; in this coal arsenic appears to be primarily organically associated. Selenium is mainly associated with pyrite in the bituminous coal samples. In two bituminous coal samples, zinc is mostly in the form of ZnS or associated with pyrite, whereas it appears to be associated with other minerals in the other two coals. Zinc is also the only trace element studied that is significantly more concentrated in the smaller (45 to 63 ??m) coal particles.

  13. A posteriori testing of algebraic flame surface density models for LES

    Science.gov (United States)

    Ma, T.; Stein, O. T.; Chakraborty, N.; Kempf, A. M.

    2013-06-01

    In the application of Large Eddy Simulation (LES) to premixed combustion, the unknown filtered chemical source term can be modelled by the generalised flame surface density (FSD) using algebraic models for the wrinkling factor Ξ. The present study compares the behaviour of the various models by first examining the effect of sub-grid turbulent velocity fluctuation on Ξ through a one-dimensional analysis and by the LES of the ORACLES burner (Nguyen, Bruel, and Reichstadt, Flow, Turbulence and Combustion Vol. 82 [2009], pp. 155-183) and the Volvo Rig (Sjunnesson, Nelsson, and Max, Laser Anemometry, Vol. 3 [1991], pp. 83-90; Sjunnesson, Henrikson, and Löfström, AIAA Journal, Vol. 28 [1992], pp. AIAA-92-3650). Several sensitivity studies on parameters such as the turbulent viscosity and the grid resolution are also carried out. A statistically 1-D analysis of turbulent flame propagation reveals that counter gradient transport of the progress variable needs to be accounted for to obtain a realistic flame thickness from the simulations using algebraic FSD based closure. The two burner setups are found to operate mainly within the wrinkling/corrugated flamelet regime based on the premixed combustion diagram for LES (Pitsch and Duchamp de Lageneste, Proceedings of the Combustion Institute, Vol. 29 [2002], pp. 2001-2008) and this suggests that the models are operating within their ideal range. The performance of the algebraic models are then assessed by comparing velocity statistics, followed by a detailed error analysis for the ORACLES burner. Four of the tested models were found to perform reasonably well against experiments, and one of these four further excels in being the most grid-independent. For the Volvo Rig, more focus is placed upon the comparison of temperature data and identifying changes in flame structure amongst the different models. It is found that the few models which largely over-predict velocities in the ORACLES case and volume averaged ? in a

  14. TEMPERATURE AND ELECTRON DENSITY DIAGNOSTICS OF A CANDLE-FLAME-SHAPED FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Guidoni, S. E. [NASA Goddard Space Flight Center/CUA, Code 674, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); McKenzie, D. E.; Longcope, D. W.; Yoshimura, K. [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States); Plowman, J. E., E-mail: silvina.e.guidoni@nasa.gov [High Altitude Observatory, National Center for Atmospheric Research P.O. Box 3000, Boulder, CO 80307-3000 (United States)

    2015-02-10

    Candle-flame-shaped flares are archetypical structures that provide indirect evidence of magnetic reconnection. A flare resembling Tsuneta's famous 1992 candle-flame flare occurred on 2011 January 28; we present its temperature and electron density diagnostics. This flare was observed with Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), Hinode/X-Ray Telescope (XRT), and Solar Terrestrial Relations Observatory Ahead (STEREO-A)/Extreme Ultraviolet Imager, resulting in high-resolution, broad temperature coverage, and stereoscopic views of this iconic structure. The high-temperature images reveal a brightening that grows in size to form a tower-like structure at the top of the posteruption flare arcade, a feature that has been observed in other long-duration events. Despite the extensive work on the standard reconnection scenario, there is no complete agreement among models regarding the nature of this high-intensity elongated structure. Electron density maps reveal that reconnected loops that are successively connected at their tops to the tower develop a density asymmetry of about a factor of two between the two legs, giving the appearance of ''half-loops''. We calculate average temperatures with a new fast differential emission measure (DEM) method that uses SDO/AIA data and analyze the heating and cooling of salient features of the flare. Using STEREO observations, we show that the tower and the half-loop brightenings are not a line-of-sight projection effect of the type studied by Forbes and Acton. This conclusion opens the door for physics-based explanations of these puzzling, recurrent solar flare features, previously attributed to projection effects. We corroborate the results of our DEM analysis by comparing them with temperature analyses from Hinode/XRT.

  15. Determination of element affinities by density fractionation of bulk coal samples

    Science.gov (United States)

    Querol, X.; Klika, Z.; Weiss, Z.; Finkelman, R.B.; Alastuey, A.; Juan, R.; Lopez-Soler, A.; Plana, F.; Kolker, A.; Chenery, S.R.N.

    2001-01-01

    A review has been made of the various methods of determining major and trace element affinities for different phases, both mineral and organic in coals, citing their various strengths and weaknesses. These include mathematical deconvolution of chemical analyses, direct microanalysis, sequential extraction procedures and density fractionation. A new methodology combining density fractionation with mathematical deconvolution of chemical analyses of whole coals and their density fractions has been evaluated. These coals formed part of the IEA-Coal Research project on the Modes of Occurrence of Trace Elements in Coal. Results were compared to a previously reported sequential extraction methodology and showed good agreement for most elements. For particular elements (Be, Mo, Cu, Se and REEs) in specific coals where disagreement was found, it was concluded that the occurrence of rare trace element bearing phases may account for the discrepancy, and modifications to the general procedure must be made to account for these.

  16. Gasification in pulverized coal flames. First annual progress report, July 1975--June 1976

    Energy Technology Data Exchange (ETDEWEB)

    Lenzer, R. C.; George, P. E.; Thomas, J. F.; Laurendeau, N. M.

    1976-07-01

    This project concerns the production of power and synthesis gas from pulverized coal via suspension gasification. Swirling flow in both concentric jet and cyclone gasifiers will separate oxidation and reduction zones. Gasifier performance will be correlated with internally measured temperature and concentration profiles. A literature review of vortex and cyclone reactors is complete. Preliminary reviews of confined jet reactors and pulverized coal reaction models have also been completed. A simple equilibrium model for power gas production is in agreement with literature correlations. Cold gas efficiency is not a suitable performance parameter for combined cycle operation. The coal handling facility, equipped with crusher, pulverizer and sieve shaker, is in working order. Test cell flow and electrical systems have been designed, and most of the equipment has been received. Construction of the cyclone gasifier has begun. A preliminary design for the gas sampling system, which will utilize a UTI Q-30C mass spectrometer, has been developed.

  17. Large-eddy simulation/probability density function modeling of local extinction and re-ignition in Sandia Flame E

    Science.gov (United States)

    Wang, Haifeng; Popov, Pavel; Hiremath, Varun; Lantz, Steven; Viswanathan, Sharadha; Pope, Stephen

    2010-11-01

    A large-eddy simulation (LES)/probability density function (PDF) code is developed and applied to the study of local extinction and re-ignition in Sandia Flame E. The modified Curl mixing model is used to account for the sub-filter scalar mixing; the ARM1 mechanism is used for the chemical reaction; and the in- situ adaptive tabulation (ISAT) algorithm is used to accelerate the chemistry calculations. Calculations are performed on different grids to study the resolution requirement for this flame. Then, with sufficient grid resolution, full-scale LES/PDF calculations are performed to study the flame characteristics and the turbulence-chemistry interactions. Sensitivity to the mixing frequency model is explored in order to understand the behavior of sub-filter scalar mixing in the context of LES. The simulation results are compared to the experimental data to demonstrate the capability of the code. Comparison is also made to previous RANS/PDF simulations.

  18. Effects of DME mixing on number density and size properties of soot particles in counterflow non-premixed ethylene flames

    KAUST Repository

    Choi, J. H.

    2015-05-01

    In order to investigate the effect of DME mixing on the number density and size of soot particles, DME was mixed in a counter flow non-premixed ethylene flame with mixture ratios of 5%, 14% and 30%. A laser extinction/scattering technique has been adopted to measure the volume fraction, number density, and mean size of soot particles. The experimental results showed that the highest soot concentrations were observed for flames with mixture ratios of 5% and 14%; however, for a mixture ratio of 30% the soot concentration decreased. Numerical results showed that the concentrations of propargyl radicals (C3H3) at the 5% and 14% ratios were higher than those measured in the ethylene-based flame, and the production of benzene (C6H6) in the 5% and 14% DME mixture flames was also increased. This indicates the crucial role of propargyl in benzene ring formation. These reactions generally become stronger with increased DME mixing, except for A1- + H2 → A1 + H (-R554) and n-C4H5 + C2H2 → A1 + H (R542). Therefore, it is indicated that adding DME to ethylene flames promotes benzene ring formation. Note that although the maximum C6H6 concentration is largest in the 30% DME mixing flame, the soot volume fraction is smaller than those for the 5% and 14% mixture ratios. This is because the local C6H6 concentration decreases in the relatively low temperature region in the fuel side where soot growth occurs. © 2015, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  19. Studying flame combustion of coal-water slurries in the furnaces of power-generating boilers

    Science.gov (United States)

    Osintsev, K. V.

    2012-06-01

    Matters concerned with organizing combustion of different types of coal-water slurries in coalfired boilers at thermal power stations are considered. Recommendations for improving the economic and environmental indicators and for achieving more reliable operation of furnace devices and boiler as a whole are given.

  20. Flame radiant image numeralization for pulverized coal combustion in BF raceway

    Institute of Scientific and Technical Information of China (English)

    WEN Liang-ying; OU Yang-qi; BAI Chen-guang; WANG Hua

    2005-01-01

    In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional radiant energy in a blast furnace raceway, focusing on the correlativity of the numerical simulation of combustion processes with the connection of radiant images information and space temperature distribution. We calculated the uneven radiate characteristic parameterby taking radiant images as a kind of radiative boundary for numerical simulation of combustion processes, and put forward a method to examine three-dimensional temperatures distribution in blast furnace raceway by radiant image processing. The numeral temperature fields matching the real combustion can be got by the numeric image processing technique.

  1. Investigations of coal ignition in a short-range flame burner using optical measuring systems; Untersuchungen zur Kohlezuendung am Flachflammenbrenner unter Verwendung optischer Messtechnik

    Energy Technology Data Exchange (ETDEWEB)

    Hackert, G.; Kremer, H.; Wirtz, S. [Bochum Univ. (Germany). Lehrstuhl fuer Energieanlagentechnik

    1999-09-01

    The short-range flame burner and the KOALA reactor of DMT are experimental facilities for realistic simulation of coal conversion processes at high temperatures and pressures in atmospheric conditions. The TOSCA system enable measurements of temperatures, sizes, shapes and velocities of the fuel particles, which serve as a basis for a three-dimensional simulation model of coal combustion. In the future, further parameter studies will deepen the present knowledge of coal dust combustion under pressure and enable optimisation of the numerical models for simulation of industrial-scale systems for coal dust combustion under pressure. [Deutsch] Mit dem Flachflammenbrenner und dem KOALA-Reaktor der DMT stehen Versuchsapparaturen zur Verfuegung, mit deren Hilfe die Kohleumwandlungsprozesse bei hohen Temperaturen unter Druck und unter atmosphaerischen Bedingungen realistisch wiedergegeben werden. Das TOSCA-System erlaubt dabei die Bestimmung von Temperaturen, Groessen, Formen und Geschwindigkeiten der Brennstoffpartikel. Diese Daten liefern die Grundlage fuer die Erstellung eines dreidimensionalen Simulationsmodells zur Modellierung der Kohleverbrennung. In Zukunft werden weitere Parameterstudien das Verstaendnis der Kohlenstaubdruckverbrennung vertiefen und ein Optimierung der numerischen Modelle ermoeglichen, so dass die Simulation grosstechnischer Kohlenstaubdruckverbrennungsanlagen realisiert werden kann. (orig.)

  2. Determination of the stagnation point in pulverized coal swirl flames by detailed analysis of laser velocity measurements; Staupunktbestimmung in Kohlenstaub-Drallflammen mittels detaillierter Analyse von LDA-Daten

    Energy Technology Data Exchange (ETDEWEB)

    Ohliger, A.; Stadler, H.; Foerster, M.; Kneer, R. [RWTH Aachen University (Germany). Lehrstuhl fuer Waerme- und Stoffuebertragung

    2009-07-01

    When Laser Doppler Anemometry (LDA) is used for experimental investigation of flow fields in pulverised coal flames, the measured coal particle velocities are usually averaged in order to determine the gas velocity. This paper shows that this approach can lead to a misinterpretation of the data. In the burner vicinity of the investigated flame, where high accelerations in the gas phase occur, a discrepancy appears between the measured velocity distribution and the expected normal distribution. Thus, a detailed analysis of the measured particle data is conducted and compared to conventional averaging. The difference can be attributed to large particles from the inner recirculation zone of the flame, which do not follow the gas flow properly. (orig.)

  3. Optimisation of coal blend and bulk density for coke ovens by vibrocompacting technique non-recovery ovens

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, P.P.; Vinoo, D.S.; Yadav, U.S.; Ghosh, S.; Lal, J.P.N. [J.S.W. Steel Ltd, Bellary (India)

    2007-09-15

    The quality of coke produced in a coke oven depends on the coal blend characteristics and carbonisation conditions. Scarcity of good quality coking coal made it necessary to look for techniques capable of producing superior coke from inferior coals. Precarbonisation techniques improve the bulk density of the coal charge and produce good quality coke from inferior coals. The stamp charging technique, the most effective among them requires finer crushing of coal and higher moisture as binder, both requiring additional energy. JSW Steel has adopted vibrocompaction along with non-recovery ovens for its 1.2 Mtpa coke production. This is a highly ecofriendly coke making process producing excellent quality coke from inferior coals. It increases the bulk density of cake, similar to stamp charging, using compaction in place of stamping. A cake density of 1.10 t m{sup -3} has been achieved using the vibrocompacting technique with optimum moisture and crushing fineness. Coal blend containing up to 35% soft coal and coking coal, having 32% volatile matter have been successfully used to produce a coke with coke strength after reaction >65%, coke reactivity index <25% and M10 <6%. The paper discusses the experience of operating vibrocompaction non-recovery coke ovens.

  4. Time-averaged probability density functions of soot nanoparticles along the centerline of a piloted turbulent diffusion flame using a scanning mobility particle sizer

    KAUST Repository

    Chowdhury, Snehaunshu

    2017-01-23

    In this study, we demonstrate the use of a scanning mobility particle sizer (SMPS) as an effective tool to measure the probability density functions (PDFs) of soot nanoparticles in turbulent flames. Time-averaged soot PDFs necessary for validating existing soot models are reported at intervals of ∆x/D∆x/D = 5 along the centerline of turbulent, non-premixed, C2H4/N2 flames. The jet exit Reynolds numbers of the flames investigated were 10,000 and 20,000. A simplified burner geometry based on a published design was chosen to aid modelers. Soot was sampled directly from the flame using a sampling probe with a 0.5-mm diameter orifice and diluted with N2 by a two-stage dilution process. The overall dilution ratio was not evaluated. An SMPS system was used to analyze soot particle concentrations in the diluted samples. Sampling conditions were optimized over a wide range of dilution ratios to eliminate the effect of agglomeration in the sampling probe. Two differential mobility analyzers (DMAs) with different size ranges were used separately in the SMPS measurements to characterize the entire size range of particles. In both flames, the PDFs were found to be mono-modal in nature near the jet exit. Further downstream, the profiles were flatter with a fall-off at larger particle diameters. The geometric mean of the soot size distributions was less than 10 nm for all cases and increased monotonically with axial distance in both flames.

  5. Flame investigations of coal and biomass combustion with a 35 MW DS {sup registered} burner and modification for indirect firing

    Energy Technology Data Exchange (ETDEWEB)

    Weirich, Tanja; Leisse, Alfons; Niesbach, Juergen; Kuhr, Christian; Koczorowski, Hans-Joachim [Hitachi Power Europe GmbH, Duisburg (Germany)

    2010-07-01

    Based on experimental flame investigations the capability of a DS {sup registered} burner to operate in a wide load range with different fuels was verified. A DS {sup registered} burner with a thermal capacity of 35 MW was installed in a combustion test facility in order to perform in-flame ash sampling and detailed measurements of temperatures, flue gas species as well as convective and radioactive heat fluxes. Moreover the DS {sup registered} burner was modified to DS {sup registered} T burner for the use of dense phase fuel conveying for indirect firing systems including the oxyfuel process. (orig.)

  6. Gasification in pulverized coal flames. Second quarterly progress report, October--December 1975. [Contains literature survey on vortex gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Lenzer, R. C.; George, P. E.; Laurendeau, N. M.

    1976-01-01

    This project is concerned with the production of power and synthesis gases from pulverized coal via suspension gasification. A literature review concerning the vortex type gasifier has been completed and a survey concerning the confined jet gasifier is underway. Preliminary design of the vortex gasifier is nearing completion. Test cell and coal handling facilities are in the final stages of design and coal handling equipment has been received. A mass spectrometer has been ordered and a preliminary survey of high-temperature probes is complete.

  7. In-plant testing of the floatex density separator for fine coal cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Reed, S.R.; Riffey, R. [Kerr McGee Coal Corp., Oklahoma City, OK (United States); Honaker, R. [Southern Illinois Univ., Carbondale, IL (United States); Mankosa, M. [Carpco, Inc., Jacksonville, FL (United States)

    1995-08-01

    A recent study found the Floatex Density Separator to be very efficient at cleaning the coarse fraction (16x100 mesh) in a typical fine coal circuit feed while achieving a throughput capacity of 2-3 tph/ft{sup 2}. Additionally, total sulfur rejection was improved by 10% as compared to typical spiral performance on this same size fraction. Based on these findings, in-plant tests using an 18x18-inch Floatex Density Separator were conducted at the Galatia preparation plant in Southern Illinois. A statistically designed test program was carried out to optimize the Floatex operating conditions and to evaluate the unit capacity and efficiency. Simultaneous samples were collected from the Floatex and the existing coal spirals to obtain a comparison of the separation performance for each unit process.

  8. High temperature erosion wear of flame and plasma-sprayed nickel-chromium coatings under simulated coal-fired boiler atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Hidalgo, V.H.; Varela, J.B.; Menendez, A.C.; Martinez, S.P. [Universidad de Oviedo, Gijon (Spain). Departamento Energia

    2001-02-01

    Erosive high temperature wear of heat exchanger tubes and other structural materials in coal-fired boilers are recognised as being the main cause of downtime at power generation plants. This study concerns the behaviour of plasma and flame sprayed modified nickel-chromium alloy (with small aluminium and titanium additions) subjected to the action of simulated post-combustion gases from a coal-fired boiler combustor. The study first evaluates the effects of thermal exposure at high temperature on the adherence between the substrate (austenitic stainless steel) and coatings. Then, the oxidation rates of these coatings in atmospheres with 3-3.5% of free oxygen at 500 and 800{degree}C (773 and 1073 K) were evaluated. The low velocity corrosion-erosion behaviour produced by the impact of fly ashes in the gas stream at high temperatures (773 and 1073 K) was also evaluated under impact angles of 30 and 90{degree}C. Finally, the eroded surfaces were analysed using scanning electron microscopy to characterise the ash embedment phenomena and the operating erosive micromechanisms. 24 refs., 13 figs., 9 tabs.

  9. 30 CFR 14.20 - Flame resistance.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Flame resistance. 14.20 Section 14.20 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF... § 14.20 Flame resistance. Conveyor belts for use in underground coal mines must be flame-resistant...

  10. Gasification in pulverized coal flames. Final report (Part I). Pulverized coal combustion and gasification in a cyclone reactor: experiment and model

    Energy Technology Data Exchange (ETDEWEB)

    Barnhart, J. S.; Laurendeau, N. M.

    1979-05-01

    A unified experimental and analytical study of pulverized coal combustion and low-BTU gasification in an atmospheric cyclone reactor was performed. Experimental results include several series of coal combustion tests and a coal gasification test carried out via fuel-rich combustion without steam addition. Reactor stability was excellent over a range of equivalence ratios from .67 to 2.4 and air flowrates from 60 to 220 lb/hr. Typical carbon efficiencies were 95% for air-rich and stoichiometric tests and 80% for gasification tests. The best gasification results were achieved at an equivalence ratio of 2.0, where the carbon, cold gas and hot gas efficiencies were 83, 45 and 75%, respectively. The corresponding product gas heating value was 70 BTU/scf. A macroscopic model of coal combustion in the cyclone has been developed. Fuel-rich gasification can also be modeled through a gas-phase equilibrium treatment. Fluid mechanics are modeled by a particle force balance and a series combination of a perfectly stirred reactor and a plug flow reactor. Kinetic treatments of coal pyrolysis, char oxidation and carbon monoxide oxidation are included. Gas composition and temperature are checked against equilibrium values. The model predicts carbon efficiency, gas composition and temperature and reactor heat loss; gasification parameters, such as cold and hot gas efficiency and make gas heating value, are calculated for fuel-rich conditions. Good agreement exists between experiment and theory for conditions of this investigation.

  11. Suppression of fine ash formation in pulverized coal flames. Final technical report, September 30, 1992--January 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Kramlich, J.C.; Chenevert, B.; Park, Jungsung; Hoffman, D.A.; Butcher, E.K.

    1996-07-19

    Coal ash, and particularly fine fly ash, remain one of the principal practical and environmental problems in coal-based power generation. In particular, submicron aerosols are identified with direct inhalation risk. Submicron ash is thought to arise from mineral vaporization during char combustion, followed by nucleation, condensation and coagulation to yield an aerosol. While aerosols are predominantly made out of volatile alkali minerals, they also can include refractory oxides that are chemically reduced to more volatile forms within the char particle and vaporized. Most of the ash of size greater than 1 {mu}m is generated by agglomeration of mineral as the char particle bums out. These two principal mechanisms are thought to account for most of the ash generated in coal combustion. Previous research has shown that various forms of coal treatment can influence the yields of fine ash from combustion. The research reported here investigates various forms of treatment, including physical coal cleaning, aerodynamic sizing, degree of grinding, and combinations of these on both aerosol yields and on yields of fine residual ash (1-4 {mu}m). The work also includes results from the combustion of artificial chars that include individual mineral elements. This research shows that these various forms of coal treatment can significantly change ash characteristics. While none of the treatments affected the bulk of the residual ash size distribution significantly, the yield of the ash aerosol mode (d<0.5 {mu}m) and fine residual ash mode (1-4 {mu}m) are changed by the treatments.

  12. MICROWAVE CO-PYROLYSIS STUDY ON LONG FLAME COAL AND COKING COAL%微波场中长焰煤与焦煤共热解实验研究

    Institute of Scientific and Technical Information of China (English)

    宋永辉; 苏婷; 兰新哲; 裴建军

    2011-01-01

    The microwave co-pyrolysis of Wangjiagou (WJG) long flame coal and coking coal (JM) were carried out in this study to know about the changes of yield and composition of coal pyrolysis product with the different ratio of two raw coals. The results showed that under microwave pyrolysis conditions, the tar yield was gradually reduced with the proportion of JM coal increases, while the ash content and sulfur content of solid coke increased, and the SEM pictures showed the area of porous surface in the solid structure of coke was bigger, the porous borders became increasingly clear. The content of CO2, CO, CH4, and CnHm were gradually increased with the pyrolysis time before 3 min then started to decreased. With the JM mixing ratio increase, the CO2, CO levels have diminished, but the change of CH4 and CHm content was not obvious before 3 min, while increased in the 3 min-15 min interval.%对王家沟(WJG)长焰煤和焦煤(JM)两种原料煤进行了微波共热解实验研究,考察了两种煤配比不同时热解产物的收率及成分变化.结果表明,微波热解条件下,随着混煤中JM比例的增大,焦油收率在逐渐减少,而固体焦的灰分含量与硫含量逐渐增加.SEM照片也表明,固体焦表面的微孔结构越来越多,微孔的边界越来越清晰.煤气中CO2,CO,CH4和CnHm含量在3 min以前随热解时间的延长均逐渐增加,随后逐步减少.随着混煤中JM配比的增大,热解煤气中CO2和CO含量逐渐减少,但CH4和CnHm含量在3 min以前变化不是很明显,在3 min~15 min区间逐渐增加.

  13. Incorporation of Copper Enhances the Anti-Ageing Property of Flame-Sprayed High-Density Polyethylene Coatings

    Science.gov (United States)

    Jia, Zhengmei; Huang, Jing; Gong, Yongfeng; Jin, Peipeng; Suo, Xinkun; Li, Hua

    2017-02-01

    High-density polyethylene (HDPE)-copper (Cu) composite coatings were prepared through depositing HDPE-Cu core-shell particles by flame spraying. The HDPE-Cu composite coatings and the HDPE coatings were aged in xenon lamp ageing testing chamber. The variations of chemical compositions and surface morphology of the coatings before and after the ageing testing were analyzed using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and ultraviolet-visible spectrophotometer. Results show that there is no chemical composition variation in the HDPE-Cu coatings. Cracks were found on the surfaces of the HDPE coatings, while the HDPE-Cu coating shows almost intact surface morphology. These results suggest that the HDPE-Cu coatings present better anti-ageing performances than the HDPE coatings. Further assessment of the function of Cu shells on the anti-ageing property reveals that Cu shells not only enhanced the absorption of the coatings to ultraviolet, but also increased their reflectivity to visible light. Additionally, the Cu shells enhanced the decomposition temperature and thermal stability of HDPE in the composite coatings. These results give bright insight into potential anti-ageing applications of the polymer-based structures.

  14. Flame retardancy effect of surface-modified metal hydroxides on linear low density polyethylene

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Metal hydroxides (MAH) consisting of magnesium hydroxide and aluminum hydroxide with a mass ratio of 1:2 were surface-modified by γ-diethoxyphosphorous ester propyldiethoxymethylsilane,boric acid and diphenylsilanediol in xylene under dibutyl tin dilaurate catalyst at 140 ℃.Phosphorus,silicon and boron elements covalently bonded to metal hydroxide particles were detected by X-ray photoelectron spectroscopy.The degradation behavior of the surface-modified MAH was characterized by thermogravimetric analysis.The results show that linear low density polyethylene (LLDPE) composite,filled with 50% (mass fraction) of MAH modified by 5.0% (mass fraction) of modifiers,passes the V-O rating of UL-94 test and shows the limited oxygen index of 34%,and its heat release rate and average effective heat combustion in a cone calorimeter measurement decrease obviously;The mechanical properties of MAH can be improved by surface-modification.The uniform dispersion of particles and strong interfacial bonding between particles and matrix are obtained.

  15. Mercury and trace element distribution in density separates of a South African Highveld (#4) coal: Implications for mercury reduction and preparation of export coal

    Science.gov (United States)

    Kolker, Allan; Senior, Connie L.; van Alphen, Chris; Koenig, Alan E.; Geboy, Nicholas J.

    2017-01-01

    Eight density separates of Permian Highveld (#4) coal were investigated for partitioning of Hg and trace elements. The separates include float fractions obtained in heavy media having densities of 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 g/cm3, and the sink fraction for 2.0 g/cm3. Bulk analysis of the separates shows strong (R2 ≥ 0.80) positive correlations between pyritic sulfur and mercury, and between ash yield and both pyritic sulfur and mercury. Laser ablation (LA) ICP-MS analysis of individual pyrite grains in the separates confirms association of Hg and As with pyrite as indicated by bulk analysis. Other elements detected in pyrite by LA-ICP-MS include Mn, Co, Ni, Tl, and Pb. Results for the separates allow prediction of Hg, trace elements, and ash yields expected in specific South African coal products. These range from 0.06 ppm Hg and an ash yield of 11.5% ash for the export fraction to 0.47 ppm Hg and an ash yield of 60.9% for the discard (stone) fraction (dry basis). Results show pronounced differences expected between coal used for domestic power generation and coal which is exported.

  16. Mathematical modeling of velocity and number density profiles of particles across the flame propagation through a micro-iron dust cloud.

    Science.gov (United States)

    Bidabadi, Mehdi; Haghiri, Ali; Rahbari, Alireza

    2010-04-15

    In this study, an attempt has been made to analytically investigate the concentration and velocity profiles of particles across flame propagation through a micro-iron dust cloud. In the first step, Lagrangian particle equation of motion during upward flame propagation in a vertical duct is employed and then forces acting upon the particle, such as thermophoretic force (resulted from the temperature gradient), gravitation and buoyancy are introduced; and consequently, the velocity profile as a function of the distance from the leading edge of the combustion zone is extracted. In the resumption, a control volume above the leading edge of the combustion zone is considered and the change in the particle number density in this control volume is obtained via the balance of particle mass fluxes passing through it. This study explains that the particle concentration at the leading edge of the combustion zone is more than the particle agglomeration in a distance far from the flame front. This increase in the particle aggregation above the combustion zone has a remarkable effect on the lower flammability limits of combustible particle cloud. It is worth noticing that the velocity and particle concentration profiles show a reasonable compatibility with the experimental data.

  17. High efficient ultrahigh acceleration of plasma blocks by PW-ps laser pulses for producing fusion flames in DT and HB11 of solid state density

    Science.gov (United States)

    Moustaizis, S.; Lalousis, P.; Hora, H.; Miley, G. H.

    2016-03-01

    Ultrahigh acceleration of plasma blocks in the range of 1020 cm/s2 has been confirmed experimentally after this was long predicted as a non-thermal direct conversion of optical energy into plasma motion due to dominating nonlinear (ponderomotive) forces [1]. The use of laser pulses of more than PW power and ps or shorter duration can ignite a nuclear fusion flame in solid density deuterium tritium because the necessary energy flux of >108J/cm2 according to the theory of Chu [2] is available [3]. For the studies of the necessary velocities of the generated fusion flames above 1000 km/s the detailed processes can be analyzed by using the advanced genuine two-fluid hydrodynamic model [4] where it was surprising that the ignition of the fusion flame by the picosecond interaction needs a comparably long development in the nanosecond range before the thermal processes result in shock fronts similar to the Rakine-Hugoniot theory. For the evaluation of power generation the problem of lateral energy losses was studied by using very high pulsed magnetic fields. The recently produced 10 Kilotesla magnetic fields [5] are very promising for solutions.

  18. 生物基阻燃聚酯多元醇聚氨酯硬泡在煤矿中的应用%Application of Biological Basis Flame Retardant Polyester Polyol for Rigid Polyurethane Foams in Coal Mine

    Institute of Scientific and Technical Information of China (English)

    蔡彬超

    2014-01-01

    Using the biological basis flame retardant polyester polyols substitute for oil based polyether polyols for rigid polyurethane foam. The substitute amount of biological basis polyester polyol in total polyesther polyol and the effect of flame retardant in the coal mine were researched. The results showed that the polyurethane foam had high compressive strength, good dimensional stability, low thermal conductivity and perfect flame retardant effect when the mass fraction of biological basis polyester polyols was 40% ~50% in total polyether. The foam index aco⁃orded with the People�s Republic of China Coal Industry Standard MT⁃113—1995 . The product safely use in coal mine was guaranteed.%用生物基阻燃聚酯多元醇替代石油基聚醚多元醇添加于聚氨酯硬泡组合聚醚中,研究了该生物基阻燃聚酯多元醇的替代量,以及在煤矿中阻燃效果。结果表明,生物基聚酯多元醇可替代部分石油基聚醚多元醇使用,当生物基聚酯多元醇在总聚醚多元醇体系中占40%~50%时,聚氨酯泡沫的压缩强度高、尺寸稳定性良好、导热系数低且阻燃效果理想,达到中华人民共和国煤炭行业MT⁃113—1995标准,保证了煤矿安全使用。

  19. 30 CFR 75.600-1 - Approved cables; flame resistance.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Approved cables; flame resistance. 75.600-1 Section 75.600-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE... cables; flame resistance. Cables shall be accepted or approved by MSHA as flame resistant....

  20. 30 CFR 75.600 - Trailing cables; flame resistance.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Trailing cables; flame resistance. 75.600 Section 75.600 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE... cables; flame resistance. Trailing cables used in coal mines shall meet the requirements established...

  1. Joule II - Programme. Clean coal technology R & D. 2nd phase. Volume III. Atmospheric combustion of pulverized coal and coal based blends for power generation

    Energy Technology Data Exchange (ETDEWEB)

    Hein, K.R.G.; Minchener, A.J.; Pruschek, R.; Roberts, P.A. [eds.

    1998-12-31

    Topics covered in this Joule II clean coal technology publication include: coal preparation and blending; cocombustion of coal with biomass and wastes; flame modelling; NO{sub x} abatement by combustion control and staging; coal quality and NO{sub x} emissions; coal combustion properties; and fluidized bed combustion of coal. All papers have been abstracted separately.

  2. Luminous Flame Temperature Distribution Measurement Using the Emission Method

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Flame temperature distribution is one of the most important characteristic parameters in combustion research. The emission method is a good way to measure the luminous flame temperature field. The maximum entropy method is introduced to the temperature distribution measurement of a luminous flame using the emission method. A simplified mathematical model was derived by combining the thermal radiation theory, reconstruction algorithm and maximum entropy method. Suitable parameters were selected in the computing process. Good experimental results were obtained with pulverized coal flames.

  3. Growth of high-density ZnO nanorods on wood with enhanced photostability, flame retardancy and water repellency

    Science.gov (United States)

    Kong, Lizhuo; Tu, Kunkun; Guan, Hao; Wang, Xiaoqing

    2017-06-01

    Zinc oxide (ZnO) nanorod arrays were successfully assembled on the wood surface in situ via a two-step process consisting of formation of ZnO seeds and subsequent crystal growth under hydrothermal conditions at a low temperature. The morphology and crystalline structure of the formed ZnO nanorods were studied by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Highly dense and uniform arrays of ZnO nanorods with well-defined hexagonal facets were generated on the wood surface by tuning the concentration of the ZnO growth solution during the hydrothermal treatment. Accelerated weathering tests indicated that the assembled ZnO nanorod arrays were highly protective against UV radiation and greatly enhanced the photostability of the coated wood. Meanwhile, the ZnO nanorod-coated wood can withstand continuous exposure to flame with only minor smoldering in contrast with the pristine wood catching fire easily and burning rapidly. Moreover, when further modified with low-surface-energy stearic acid, the ZnO nanorod decorated wood surface can be transformed into a superhydrophobic surface, with a water contact angle (CA) of ∼154°. Such ZnO nanorod-modified woods with enhanced photostability, flame retardancy and water repellency offer an interesting alternative to conventional wood preservation strategies, highlighting their potential applications in some novel wood products.

  4. Effect of Oxygen Enrichment in Propane Laminar Diffusion Flames under Microgravity and Earth Gravity Conditions

    Science.gov (United States)

    Bhatia, Pramod; Singh, Ravinder

    2017-01-01

    Diffusion flames are the most common type of flame which we see in our daily life such as candle flame and match-stick flame. Also, they are the most used flames in practical combustion system such as industrial burner (coal fired, gas fired or oil fired), diesel engines, gas turbines, and solid fuel rockets. In the present study, steady-state global chemistry calculations for 24 different flames were performed using an axisymmetric computational fluid dynamics code (UNICORN). Computation involved simulations of inverse and normal diffusion flames of propane in earth and microgravity condition with varying oxidizer compositions (21, 30, 50, 100 % O2, by mole, in N2). 2 cases were compared with the experimental result for validating the computational model. These flames were stabilized on a 5.5 mm diameter burner with 10 mm of burner length. The effect of oxygen enrichment and variation in gravity (earth gravity and microgravity) on shape and size of diffusion flames, flame temperature, flame velocity have been studied from the computational result obtained. Oxygen enrichment resulted in significant increase in flame temperature for both types of diffusion flames. Also, oxygen enrichment and gravity variation have significant effect on the flame configuration of normal diffusion flames in comparison with inverse diffusion flames. Microgravity normal diffusion flames are spherical in shape and much wider in comparison to earth gravity normal diffusion flames. In inverse diffusion flames, microgravity flames were wider than earth gravity flames. However, microgravity inverse flames were not spherical in shape.

  5. Effect of Oxygen Enrichment in Propane Laminar Diffusion Flames under Microgravity and Earth Gravity Conditions

    Science.gov (United States)

    Bhatia, Pramod; Singh, Ravinder

    2017-06-01

    Diffusion flames are the most common type of flame which we see in our daily life such as candle flame and match-stick flame. Also, they are the most used flames in practical combustion system such as industrial burner (coal fired, gas fired or oil fired), diesel engines, gas turbines, and solid fuel rockets. In the present study, steady-state global chemistry calculations for 24 different flames were performed using an axisymmetric computational fluid dynamics code (UNICORN). Computation involved simulations of inverse and normal diffusion flames of propane in earth and microgravity condition with varying oxidizer compositions (21, 30, 50, 100 % O2, by mole, in N2). 2 cases were compared with the experimental result for validating the computational model. These flames were stabilized on a 5.5 mm diameter burner with 10 mm of burner length. The effect of oxygen enrichment and variation in gravity (earth gravity and microgravity) on shape and size of diffusion flames, flame temperature, flame velocity have been studied from the computational result obtained. Oxygen enrichment resulted in significant increase in flame temperature for both types of diffusion flames. Also, oxygen enrichment and gravity variation have significant effect on the flame configuration of normal diffusion flames in comparison with inverse diffusion flames. Microgravity normal diffusion flames are spherical in shape and much wider in comparison to earth gravity normal diffusion flames. In inverse diffusion flames, microgravity flames were wider than earth gravity flames. However, microgravity inverse flames were not spherical in shape.

  6. Development of high energy density fuels from mild gasification of coal. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-01

    METC has concluded that MCG technology has the potential to simultaneously satisfy the transportation and power generation fuel needs in the most cost-effective manner. MCG is based on low temperature pyrolysis, a technique known to the coal community for over a century. Most past pyrolysis developments were aimed at maximizing the liquids yield which results in a low quality tarry product requiring significant and capital intensive upgrading. By properly tailoring the pyrolysis severity to control the liquid yield-liquid quality relationship, it has been found that a higher quality distillate-boiling liquid can be readily ``skimmed`` from the coal. The resultant liquids have a much higher H/C ratio than conventional pyrolytic tars and therefore can be hydroprocessed at lower cost. These liquids are also extremely enriched in l-, 2-, and 3-ring aromatics. The co-product char material can be used in place of coal as a pulverized fuel (pf) for power generation in a coal combustor. In this situation where the original coal has a high sulfur content, the MCG process can be practiced with a coal-lime mixture and the calcium values retained on the char can tie up the unconverted coal sulfur upon pf combustion of the char. Lime has also been shown to improve the yield and quality of the MCG liquids.

  7. Development of high energy density fuels from mild gasification of coal

    Energy Technology Data Exchange (ETDEWEB)

    Greene, Marvin

    1991-12-01

    METC has concluded that MCG technology has the potential to simultaneously satisfy the transportation and power generation fuel needs in the most cost-effective manner. MCG is based on low temperature pyrolysis, a technique known to the coal community for over a century. Most past pyrolysis developments were aimed at maximizing the liquids yield which results in a low quality tarry product requiring significant and capital intensive upgrading. By properly tailoring the pyrolysis severity to control the liquid yield-liquid quality relationship, it has been found that a higher quality distillate-boiling liquid can be readily skimmed'' from the coal. The resultant liquids have a much higher H/C ratio than conventional pyrolytic tars and therefore can be hydroprocessed at lower cost. These liquids are also extremely enriched in l-, 2-, and 3-ring aromatics. The co-product char material can be used in place of coal as a pulverized fuel (pf) for power generation in a coal combustor. In this situation where the original coal has a high sulfur content, the MCG process can be practiced with a coal-lime mixture and the calcium values retained on the char can tie up the unconverted coal sulfur upon pf combustion of the char. Lime has also been shown to improve the yield and quality of the MCG liquids.

  8. Recent Advances in Flame Tomographyt

    Institute of Scientific and Technical Information of China (English)

    闫勇; 邱天; 卢钢; M.M.Hossain; G.Gilabert; 刘石

    2012-01-01

    To reduce greenhouse gas emissions from fossil fuel fired power plants,a range of new combustion technologies are being developed or refined,including oxy-fuel combustion,co-firing biomass with coal and fluidized bed combustion.Flame characteristics under such combustion conditions are expected to be different from those in normal air fired combustion processes.Quantified flame characteristics such as temperature distribution,oscillation frequency,and ignition volume play an important part in the optimized design and operation of the environmentally friendly power generation systems.However,it is challenging to obtain such flame characteristics particularly through a three-dimensional and non-intrusive means.Various tomography methods have been proposed to visualize and characterize flames,including passive optical tomography,laser based tomography,and electrical tomography.This paper identifies the challenges in flame tomography and reviews existing techniques for the quantitative characterization of flames.Future trends in flame tomography for industrial applications are discussed.

  9. Flame Length

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Flame length was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The tool...

  10. Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model.

    Science.gov (United States)

    Fitzgerald, James E; Robinson, Robert L; Gasem, Khaled A M

    2006-11-07

    The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO2 sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO2 on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO2 on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties.

  11. In depth fusion flame spreading with a deuterium-tritium plane fuel density profile for plasma block ignition

    Institute of Scientific and Technical Information of China (English)

    B.Malekynia; S.S.Razavipour

    2012-01-01

    Solid-state fuel ignition was given by Chu and Bobin according to the hydrodynamic theory at x =0 qualitatively.A high threshold energy flux density,i.e.,E* =4.3 x 1012 J/m2,has been reached.Recently,fast ignition by employing clean petawatt-picosecond laser pulses was performed.The anomalous phenomena were observed to be based on suppression of prepulses.The accelerated plasma block was used to ignite deuterium-tritium fuel at solid-state density.The detailed analysis of the thermonuclear wave propagation was investigated.Also the fusion conditions at x ≠ 0 layers were clarified by exactly solving hydrodynamic equations for plasma block ignition.In this paper,the applied physical mechanisms are determined for nonlinear force laser driven plasma blocks,thermonuclear reaction,heat transfer,electron-ion equilibration,stopping power of alpha particles,bremsstrahlung,expansion,density dependence,and fluid dynamics.New ignition conditions may be obtained by using temperature equations,including thc dcnsity profile that is obtained by the continuity equation and expansion velocity.The density is only a function of x and independent of time.The ignition energy flux density,E*t,for the x ≠ 0 layers is 1.95 × 1012 J/m2.Thus threshold ignition energy in comparison with that at x =0 layers would be reduced to less than 50 percent.

  12. High energy density capacitor using coal tar pitch derived nanoporous carbon/MnO{sub 2} electrodes in aqueous electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Tomko, Timothy [Energy and Mineral Engineering, University Park, PA 16802 (United States); Rajagopalan, Ramakrishnan; Lanagan, Michael [Materials Research Institute, University Park, PA 16802 (United States); Foley, Henry C. [Department of Chemical Engineering, University Park, PA 16802 (United States)

    2011-02-15

    Asymmetric aqueous electrochemical capacitors with energy densities as high as 22 Wh kg{sup -1}, power densities of 11 kW kg{sup -1} and a cell voltage of 2 V were fabricated using cost effective, high surface carbon derived from coal tar pitch and manganese dioxide. The narrow pore size distribution of the activated carbon (mean pore size {proportional_to}0.8 nm) resulted in strong electroadsorption of protons making them suitable for use as negative electrodes. Amorphous manganese dioxide anodes were synthesized by chemical precipitation method with high specific capacitance (300 F g{sup -1}) in aqueous electrolytes containing bivalent cations. The fabricated capacitors demonstrated excellent cyclability with no signs of capacitance fading even after 1000 cycles. (author)

  13. Beam steering effects in turbulent high pressure flames

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The propagation of a laser beam through a flame is influenced by variations of the optical density. Especially in turbulent high pressure flames this may seriously limit the use of laser diagnostic methods. (author) 1 fig., 2 refs.

  14. On-line micro-volume introduction system developed for lower density than water extraction solvent and dispersive liquid-liquid microextraction coupled with flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Anthemidis, Aristidis N., E-mail: anthemid@chem.auth.gr [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece); Mitani, Constantina; Balkatzopoulou, Paschalia; Tzanavaras, Paraskevas D. [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece)

    2012-07-06

    Highlights: Black-Right-Pointing-Pointer A dispersive liquid-liquid micro extraction method for lead and copper determination. Black-Right-Pointing-Pointer A micro-volume transportation system for extractant solvent lighter than water. Black-Right-Pointing-Pointer Analysis of natural water samples. - Abstract: A simple and fast preconcentration/separation dispersive liquid-liquid micro extraction (DLLME) method for metal determination based on the use of extraction solvent with lower density than water has been developed. For this purpose a novel micro-volume introduction system was developed enabling the on-line injection of the organic solvent into flame atomic absorption spectrometry (FAAS). The effectiveness and efficiency of the proposed system were demonstrated for lead and copper preconcentration in environmental water samples using di-isobutyl ketone (DBIK) as extraction solvent. Under the optimum conditions the enhancement factor for lead and copper was 187 and 310 respectively. For a sample volume of 10 mL, the detection limit (3 s) and the relative standard deviation were 1.2 {mu}g L{sup -1} and 3.3% for lead and 0.12 {mu}g L{sup -1} and 2.9% for copper respectively. The developed method was evaluated by analyzing certified reference material and it was applied successfully to the analysis of environmental water samples.

  15. 30 CFR 77.1102 - Warning signs; smoking and open flame.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Warning signs; smoking and open flame. 77.1102... COAL MINES Fire Protection § 77.1102 Warning signs; smoking and open flame. Signs warning against smoking and open flames shall be posted so they can be readily seen in areas or places where fire...

  16. 30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

    Science.gov (United States)

    2010-07-01

    ... flame underground. 75.1106 Section 75.1106 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. All welding, cutting, or...

  17. 可调煤粉浓度燃烧装置内的流动特性分析%Analysis on flow feature of adjustable coal powder density in coal-fired combustion device

    Institute of Scientific and Technical Information of China (English)

    于静梅; 郭仁宁

    2009-01-01

    针对某电厂燃煤种类多变而导致结焦严重状况,对煤粉分离装置进行改造并进行了数值模拟,采用RNG K-3模型和颗粒轨道模型为理论模型,对改造前后进行分析得到了速度场和浓度分布,改造后有利于在向火侧得到更高的煤粉浓度,有利于燃烧,对于指导运行有一定的帮助.%According to the serious coking status caused by the multi kind coal and variation in a coal-fired power plant, a reconstruction and numerical simulation were made for the coal powder separation device.With the RNG K-3 model and the particle trace model as the theoretical model,the speed field and the density distribution were obtained from the analysis before and after the reconstruction.After the reconstruction,it was favorable to obtain the higher coal powder density at the firing side and it was favorable for the coal combustion which could provide the certain assistance to guide the operation.

  18. Flames in vortices & tulip-flame inversion

    Science.gov (United States)

    Dold, J. W.

    This article summarises two areas of research regarding the propagation of flames in flows which involve significant fluid-dynamical motion [1]-[3]. The major difference between the two is that in the first study the fluid motion is present before the arrival of any flame and remains unaffected by the flame [1, 2] while, in the second study it is the flame that is responsible for all of the fluid dynamical effects [3]. It is currently very difficult to study flame-motion in which the medium is both highly disturbed before the arrival of a flame and is further influenced by the passage of the flame.

  19. Effect of dosage of expandable graphite, dimethyl methylphosphonate, triethanolamine, and isocyanate on fluidity, mechanical, and flame retardant properties of polyurethane materials in coal reinforcement

    Institute of Scientific and Technical Information of China (English)

    Hu Xiangming; Wang Deming; Cheng Weimin

    2016-01-01

    In this study, orthogonal experiments were conducted to investigate the influence of expandable graphite (EG), dimethyl methylphosphonate (DMMP), triethanolamine (TEA), and isocyanate content on the com-pressive and bonding strengths, oxygen index, and fluidity of rigid polyurethane foam (RPUF). The results revealed that EG significantly increased the oxygen index of RPUF, enlarged the diameter of foam cells, and decreased the cell-closed content in foam;thus, leading to a pressure drop in RPUF. However, exces-sive EG was capable of reducing the fluidity of polyurethane slurry. TEA exhibited significant influence on the compressive strength of RPUF, which dropped initially, and then increased. DMMP had a remarkable effect on the flame retardant property and compressive strength of RPUF. Compressive strength of RPUF initially displayed an increase followed by a decrease with increasing dosage of DMMP, and achieved the maximum value at DMMP dosage of 4%. DMMP could effectively reduce the diameter of RPUF cells lead-ing to an increase in the percentage of close area in foam. DMMP displayed the flame-retardation effects mainly in the gas phase leading to a significant enhancement in the oxygen index of RPUF. Moreover, the compressive strength and bonding strength of RPUF decrease significantly with the increase of isocyanate content due to the increased blowing efficiency by the CO2. The oxygen index and flowing length of foam increased with the increase in isocyanate dosage.

  20. Effect of stocking density on extensive production of freshwater shrimp in coal mine reclamation ponds

    Energy Technology Data Exchange (ETDEWEB)

    Tidwell, J.H.; Wynne, F.; Coyle, S.D. [Kentucky State Univ., Frankfort, KY (United States). Aquaculture Research Center; Grey, B. [Peabody Coal Co., Rockport, KY (United States); McGuire, J.

    1998-12-31

    The use of post-mining reclamation ponds for the production of freshwater shrimp was evaluated by examining different stocking densities. Juvenile shrimp (Macrobrachium rosenbergii) averaging 0.5g each were stocked into four existing ponds at Peabody`s Ken Surface Mine at 6,175; 12,350; 18,500; and 24,700/ha (2,500, 5,000, 7,500, and 10,000/acre) on June 1, 1995. Shrimp were fed twice a week for 103 days, with harvest conducted September 13, 1995. Survival averaged 40%, overall. Average individual weight size was inversely related to stocking density ranging from 52 g (8.7 shrimp/lb) at 6,175/ha to 20.3 g (22.7 shrimp/lb) at 18,500/acre. Total production was directly related to stocking density ranging from 97 kg/ha (86 lbs/acre) at low density to 211 kg/ha (188 lbs/acre) at 18,500/ha shrimp acre. The major difficulty was at harvest due to difficulty in draining ponds. Construction of designed culture ponds with gravity drains during reclamation could greatly enhance survival, harvestability, and commercial feasibility.

  1. Experiment study on the propagation laws of gas and coal dust explosion in coal mine

    Energy Technology Data Exchange (ETDEWEB)

    Rong-jun Si; Run-zhi Li; Lei Wang; Zi-ke Wu [China Coal Research Institute, Chongqing (China). Chongqing Research Institute

    2009-09-15

    An experiment of gas and coal dust explosion propagation in a single laneway was carried out in a large experimental roadway that is nearly the same with actual environment and geometry conditions. In the experiment, the time when the gas and coal dust explosion flame reaches test points has a logarithmic function relation with the test point distances. The explosion flame propagation velocity rises rapidly in the foreside of the coal dust segment and then decreases. The length of the flame area is about 2 times that of the original coal dust accumulation area. Shock wave pressure comes down to the rock bottom in the coal dust segment, then reaches a maximum peak rapidly and decreases. The theoretical basis of the research and assemble of across or explosion is supplied by the experiment conclusion. Compared with gas explosion, the force and destruction degree of a gas and coal dust explosion is much larger. 3 refs., 6 figs., 3 tabs.

  2. Experiment study on the propagation laws of gas and coal dust explosion in coal mine

    Institute of Scientific and Technical Information of China (English)

    SI Rong-jun; LI Run-zhi; WANG Lei; WU Zi-ke

    2009-01-01

    The experiment of gas and coal dust explosion propagation in a single laneway was carried out in a large experimental roadway that is nearly the same with actual envi-ronment and geometry conditions. In the experiment, the time when the gas and coal dust explosion flame reaches test points has a logarithmic function relation with the test point distances. The explosion flame propagation velocity rises rapidly in the foreside of the coal dust segment and comes down after that. The length of the flame area is about 2 times that of the original coal dust accumulation area. Shock wave pressure comes down to the rock bottom in the coal dust segment, then reaches the maximum peak rapidly and comes down. The theoretical basis of the research and assemble of across or explosion is sup-plied by the experiment conclusion. Compared with gas explosion, the force and destruc-tion degree of gas and coal dust explosion is much larger.

  3. On the dynamics of flame edges in diffusion-flame/vortex interactions

    Energy Technology Data Exchange (ETDEWEB)

    Hermanns, Miguel; Linan, Amable [Departamento de Motopropulsion y Termofluidodinamica, Universidad Politecnica de Madrid, Pza. Cardenal Cisneros 3, 28040 Madrid (Spain); Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2007-04-15

    We analyze the local flame extinction and reignition of a counterflow diffusion flame perturbed by a laminar vortex ring. Local flame extinction leads to the appearance of flame edges separating the burning and extinguished regions of the distorted mixing layer. The dynamics of these edges is modeled based on previous numerical results, with heat release effects fully taken into account, which provide the propagation velocity of triple and edge flames in terms of the upstream unperturbed value of the scalar dissipation. The temporal evolution of the mixing layer is determined using the classical mixture fraction approach, with both unsteady and curvature effects taken into account. Although variable density effects play an important role in exothermic reacting mixing layers, in this paper the description of the mixing layer is carried out using the constant density approximation, leading to a simplified analytical description of the flow field. The mathematical model reveals the relevant nondimensional parameters governing diffusion-flame/vortex interactions and provides the parameter range for the more relevant regime of local flame extinction followed by reignition via flame edges. Despite the simplicity of the model, the results show very good agreement with previously published experimental results. (author)

  4. 30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near...

  5. Flame structure of methane inverse diffusion flame

    KAUST Repository

    Elbaz, Ayman M.

    2014-07-01

    This paper presents high speed images of OH-PLIF at 10. kHz simultaneously with 2D PIV (particle image velocimetry) measurements collected along the entire length of an inverse diffusion flame with circumferentially arranged methane fuel jets. For a fixed fuel flow rate, the central air jet Re was varied, leading to four air to fuel velocity ratios, namely Vr = 20.7, 29, 37.4 and 49.8. A double flame structure could be observed composed of a lower fuel entrainment region and an upper mixing and intense combustion region. The entrainment region was enveloped by an early OH layer, and then merged through a very thin OH neck to an annular OH layer located at the shear layer of the air jet. The two branches of this annular OH layer broaden as they moved downstream and eventfully merged together. Three types of events were observed common to all flames: breaks, closures and growing kernels. In upstream regions of the flames, the breaks were counterbalanced by flame closures. These breaks in OH signal were found to occur at locations where locally high velocity flows were impinging on the flame. As the Vr increased to 37.4, the OH layers became discontinuous over the downstream region of the flame, and these regions of low or no OH moved upstream. With further increases in Vr, these OH pockets act as flame kernels, growing as they moved downstream, and became the main mechanism for flame re-ignition. Along the flame length, the direction of the two dimensional principle compressive strain rate axis exhibited a preferred orientation of approximately 45° with respect to the flow direction. Moreover, the OH zones were associated with elongated regions of high vorticity. © 2013 Elsevier Inc.

  6. Candle flames in microgravity

    Science.gov (United States)

    Dietrich, D. L.; Ross, H. D.; Tien, J. S.

    1995-01-01

    The candle flame in both normal and microgravity is non-propagating. In microgravity, however, the candle flame is also non-convective where (excepting Stefan flow) pure diffusion is the only transport mode. It also shares many characteristics with another classical problem, that of isolated droplet combustion. Given their qualitatively similar flame shapes and the required heat feedback to condensed-phase fuels, the gas-phase flow and temperature fields should be relatively similar for a droplet and a candle in reduced gravity. Unless the droplet diameter is maintained somehow through non-intrusive replenishment of fuel, the quasi-steady burning characteristics of a droplet can be maintained for only a few seconds. In contrast, the candle flame in microgravity may achieve a nearly steady state over a much longer time and is therefore ideal for examining a number of combustion-related phenomena. In this paper, we examine candle flame behavior in both short-duration and long-duration, quiescent, microgravity environments. Interest in this type of flame, especially 'candle flames in weightlessness', is demonstrated by very frequent public inquiries. The question is usually posed as 'will a candle flame burn in zero gravity', or, 'will a candle burn indefinitely (or steadily) in zero gravity in a large volume of quiescent air'. Intuitive speculation suggests to some that, in the absence of buoyancy, the accumulation of products in the vicinity of the flame will cause flame extinction. The classical theory for droplet combustion with its spherically-shaped diffusion flame, however, shows that steady combustion is possible in the absence of buoyancy if the chemical kinetics are fast enough. Previous experimental studies of candle flames in reduced and microgravity environments showed the flame could survive for at least 5 seconds, but did not reach a steady state in the available test time.

  7. Numerical solution of an edge flame boundary value problem

    Science.gov (United States)

    Shields, Benjamin; Freund, Jonathan; Pantano, Carlos

    2016-11-01

    We study edge flames for modeling extinction, reignition, and flame lifting in turbulent non-premixed combustion. An adaptive resolution finite element method is developed for solving a strained laminar edge flame in the intrinsic moving frame of reference of a spatially evolving shear layer. The variable-density zero Mach Navier-Stokes equations are used to solve for both advancing and retreating edge flames. The eigenvalues of the system are determined simultaneously (implicitly) with the scalar fields using a Schur complement strategy. A homotopy transformation over density is used to transition from constant- to variable-density, and pseudo arc-length continuation is used for parametric tracing of solutions. Full details of the edge flames as a function of strain and Lewis numbers will be discussed. This material is based upon work supported [in part] by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002374.

  8. Flame Holder System

    Science.gov (United States)

    Haskin, Henry H. (Inventor); Vasquez, Peter (Inventor)

    2013-01-01

    A flame holder system includes a modified torch body and a ceramic flame holder. Catch pin(s) are coupled to and extend radially out from the torch body. The ceramic flame holder has groove(s) formed in its inner wall that correspond in number and positioning to the catch pin(s). Each groove starts at one end of the flame holder and can be shaped to define at least two 90.degree.turns. Each groove is sized to receive one catch pin therein when the flame holder is fitted over the end of the torch body. The flame holder is then manipulated until the catch pin(s) butt up against the end of the groove(s).

  9. Chemistry and flow in industrial diffusion flames. Chemie und Stroemung bei technischen Diffusionsflammen

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    A total of nine papers were presented at the seminar. The papers have the following titles: laminar flamelet models for describing the combustion characteristics of pre-mixed and non-mixed turbulent flames; testing chemical-kinetic models by laser-optical measurement of concentration paths in flames; the simulation of turbulent CO-air and CH/sub 4/-air diffusion flames in consideration of complex reaction mechanisms; measurement and computer results from turbulent swirling flows; heat transfer by gas and soot formation in turbulent flames; reaction sequences in pulverised-coal flames; mathematical model formation of pulverised-coal combustion in large-scale combustion plants; calculating flows in practical burner and combustion-chamber configurations and groundwork for describing gas radiation in gas-turbine combustion chambers. Three of the papers have been abstracted separately.

  10. Flame Retardation Modification of Paper-Based PVC Wallcoverings

    Directory of Open Access Journals (Sweden)

    Lin Hui

    2016-01-01

    Full Text Available The flame-retarded paper-based polyvinyl chloride (PVC wallcoverings were successfully prepared, using plant fiber paper as base material and adding inorganic flame retardants and flame-retarded plasticizer as additives. Flame retardancy, thermostability, smoke suppression and mechanical properties were tested regarding to the prepared wallcoverings. The results showed that 2ZnO·3B2O3·3.5H2O could improve flame retardancy and thermostability of paper-based PVC wallcoverings; plasticizer tricresyl phosphate increased flame retardancy of the prepared materials auxiliarily. Also, flame-retarded paper-based PVC wallcoverings with higher flame retardancy, smoke suppression and mechanical property was prepared using plant fiber paper with fix quantity of 90 g/m3 as base material, using 2ZnO·3B2O3·3.5H2O as inorganic flame retardant, and using tricresyl phosphate as plasticizer. For the flame-retarded paper-based PVC wallcoverings in this study, the limit oxygen index (LOI reaches 32.3, maximal smoke density is 16.91 %, and the horizontal and longitudinal wet tensile strength reaches 1.38 kN·m−1 and 1.51 kN·m−1 respectively. Meanwhile, its flame retardancy meets the requirements about flame retardancy for material Class B1 listed in Chinese National Standards GB 8624-2012, Classification for burning behavior of building materials and products. This research creates an effective path to prepare paper-based PVC wallcoverings with high flame retardancy.

  11. Measuring Apparatus for Coal Powder

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The measuring apparatus for coal powder, equipped with radioactive source, is a set of device andcan be used to measure the density in the pipes and cumulative consumed amount of coal powder in apower plant, and to examine and display the status of the coal powder input system. It is sketched asFig. 1.

  12. Flame image monitoring and analysis in combustion management

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, D. [CEZ, a.s. Elektrarna Detmarovice, Detmarovice (Czech Republic); Huttunen, A.J.; Nihtinen, J.J. [Imatran Voima Oy, IVO Technology Centre, Vantaa (Finland)

    1997-12-31

    When NO{sub x} emissions are reduced with new low-NO{sub x} burners and infurnace modifications in old pulverised fuel boilers, many changes in the firing conditions may occur. Depending on coal quality and the original furnace design, low-NO{sub x} burners, overtire air, low-excess-air firing and other primary modifications in various combinations may cause flame instability, increased slagging, increased minimum load and other difficulties in controlling the burning process. To find and solve these problems quicker, a new type of burner management system for pulverised fuel and oil-fired boilers was developed by Imatran Voima Oy. The DIMAC combustion management system monitors and analyses individually each burner or burner level. There are special software for wall and corner fired boilers. The DIMAC system is comprised of two functional subsystems: flame monitoring and flame analysis. The DIMAC enables the power plant operators to minimise NO{sub x} emissions and optimise the burning efficiency with varying coal qualities and boiler loads at the same time so that slagging, unburnt carbon in fly ash and flame stability stay in acceptable limits. It also guarantees that burners operate in good safety conditions in each burner level. The DIMAC system monitors perpendicularly each individual burner and evaluates flame parameters. Real-time flame monitoring and analysis allows the operator to directly see the effect of changing fuel distribution on flame pattern and flame stability. Based on data from the DIMAC references the system can improve boiler efficiency by 0.2 - 0.5 per cent unit as a result of more efficient control of the burning process. At the same time, the NO{sub x} formation can be reduced by 10 - 20 % 2 refs.

  13. Hi-tech Flame

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Modern science plays a crucial role in lighting the Olympic flame on the world’s highest mountain when the world saw live telecasts of the Olympic flame burning onthe top of Mount Qomolangma(Mount Everest) at 9:17 on the morning of May 8, few realized the years of work and high level of technology that had

  14. Unsteady Flame Embedding

    KAUST Repository

    El-Asrag, Hossam A.

    2011-01-01

    Direct simulation of all the length and time scales relevant to practical combustion processes is computationally prohibitive. When combustion processes are driven by reaction and transport phenomena occurring at the unresolved scales of a numerical simulation, one must introduce a dynamic subgrid model that accounts for the multiscale nature of the problem using information available on a resolvable grid. Here, we discuss a model that captures unsteady flow-flame interactions- including extinction, re-ignition, and history effects-via embedded simulations at the subgrid level. The model efficiently accounts for subgrid flame structure and incorporates detailed chemistry and transport, allowing more accurate prediction of the stretch effect and the heat release. In this chapter we first review the work done in the past thirty years to develop the flame embedding concept. Next we present a formulation for the same concept that is compatible with Large Eddy Simulation in the flamelet regimes. The unsteady flame embedding approach (UFE) treats the flame as an ensemble of locally one-dimensional flames, similar to the flamelet approach. However, a set of elemental one-dimensional flames is used to describe the turbulent flame structure directly at the subgrid level. The calculations employ a one-dimensional unsteady flame model that incorporates unsteady strain rate, curvature, and mixture boundary conditions imposed by the resolved scales. The model is used for closure of the subgrid terms in the context of large eddy simulation. Direct numerical simulation (DNS) data from a flame-vortex interaction problem is used for comparison. © Springer Science+Business Media B.V. 2011.

  15. Two-Nozzle Flame Spray Pyrolysis (FSP) Synthesis of CoMo/Al2O3 Hydrotreating Catalysts

    DEFF Research Database (Denmark)

    Høj, Martin; Pham, David K.; Brorson, Michael

    2013-01-01

    Two-nozzle frame spray analysis (FSP) synthesis of CoMo/Al2O3 where Co and Al are sprayed in separate flames was applied to minimize the formation of CoAl2O4 observed in one-nozzle flame spray pyrolysis (FSP) synthesis and the materials were characterized by N2-adsorption (BET), X-ray diffraction...

  16. Measurements of turbulent premixed flame dynamics using cinema stereoscopic PIV

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Adam M.; Driscoll, James F. [University of Michigan, Department of Aerospace Engineering, Ann Arbor, MI (United States); Ceccio, Steven L. [University of Michigan, Department of Mechanical Engineering, Ann Arbor, MI (United States)

    2008-06-15

    A new experimental method is described that provides high-speed movies of turbulent premixed flame wrinkling dynamics and the associated vorticity fields. This method employs cinema stereoscopic particle image velocimetry and has been applied to a turbulent slot Bunsen flame. Three-component velocity fields were measured with high temporal and spatial resolutions of 0.9 ms and 140{mu}m, respectively. The flame-front location was determined using a new multi-step method based on particle image gradients, which is described. Comparisons are made between flame fronts found with this method and simultaneous CH-PLIF images. These show that the flame contour determined corresponds well to the true location of maximum gas density gradient. Time histories of typical eddy-flame interactions are reported and several important phenomena identified. Outwardly rotating eddy pairs wrinkle the flame and are attenuated at they pass through the flamelet. Significant flame-generated vorticity is produced downstream of the wrinkled tip. Similar wrinkles are caused by larger groups of outwardly rotating eddies. Inwardly rotating pairs cause significant convex wrinkles that grow as the flame propagates. These wrinkles encounter other eddies that alter their behavior. The effects of the hydrodynamic and diffusive instabilities are observed and found to be significant contributors to the formation and propagation of wrinkles. (orig.)

  17. Analysis of Reaction-Diffusion Systems for Flame Capturing in Type Ia Supernova Simulations

    CERN Document Server

    Zhiglo, Andrey V

    2009-01-01

    We present a study of numerical behavior of a thickened flame used in Flame Capturing (FC, Khokhlov (1995)) for tracking thin unresolved physical flames in deflagration simulations. We develop a steady-state procedure for calibrating the flame model used, and test it against analytical results. We observe numerical noises generated by original realization of the technique. Alternative artificial burning rates are discussed, which produce acceptably quiet flames. Two new quiet models are calibrated to yield required "flame" speed and width, and further studied in 2D and 3D setting. Landau-Darrieus type instabilities of the flames are observed. One model also shows significantly anisotropic propagation speed on the grid, both effects increasingly pronounced at larger matter expansion as a result of burning; this makes the model unacceptable for use in type Ia supernova simulations. Another model looks promising for use in flame capturing at fuel to ash density ratio of order 3 and below. That "Model B" yields f...

  18. Pdf prediction of supersonic hydrogen flames

    Science.gov (United States)

    Eifler, P.; Kollmann, W.

    1993-01-01

    A hybrid method for the prediction of supersonic turbulent flows with combustion is developed consisting of a second order closure for the velocity field and a multi-scalar pdf method for the local thermodynamic state. It is shown that for non-premixed flames and chemical equilibrium mixture fraction, the logarithm of the (dimensionless) density, internal energy per unit mass and the divergence of the velocity have several advantages over other sets of scalars. The closure model is applied to a supersonic non-premixed flame burning hydrogen with air supplied by a supersonic coflow and the results are compared with a limited set of experimental data.

  19. Linear Low Density Polyethylene Retarded by Synergistic Flame Retardant of OMMT/IFR%纳米蒙脱土/月彭胀型阻燃剂协同阻燃线性低密度聚乙烯

    Institute of Scientific and Technical Information of China (English)

    孟圆圆; 公维光; 郑柏存; 孟鑫

    2012-01-01

    Linear low density polyethylene (LLDPE) was modified by intumescent flame retardant (IFR) and organic montmorillonite (OMMT). The synergistic influences of IFR and OMMT on the flammability, mechanical properties of flame-retardant LLDPE were investigated. The flammability and degradation progress of the composites and the obtained charred layers were analyzed by limiting oxygen index (LOI), TGA and SEM. The results show that the addition of OMMT deteriorates the flammability, increases mechanical properties of LLDPE/IFR, and decreases the melt dripping and dense smoke to some extent. When the content of IFR and OMMT is 30phr and 2 % respectively, the LOI value of the system is 25.2 %, and the sample could form compact charred layer after burning.%以膨胀型阻燃剂(IFR)和自制的有机蒙脱土(OMMT)协同阻燃荆对线型低密度聚乙烯(LLDPE)进行阻燃改性,研究了阻燃剂和协同阻燃剂对LLDPE燃烧性能、力学性能的影响。运用极限氧指数(LOI)和热重分析(TGA)表征了LLDPE的阻燃性能,通过扫描电子显微镜(SEM)观察燃烧残余物的炭层形貌。结果表明,0MMT的加入增强了LLDPE/IFR体系的阻燃性能和力学性能,且在一定程度上解决了体系燃烧时的熔滴和浓烟现象;当IFR用量为30份,有机蒙脱土用量为2%时,体系的极限氧指数达到25.2%,燃烧残余物形成致密的炭层。

  20. OPTIMIZATION OF COAL PARTICLE FLOW PATTERNS IN LOW NOX BURNERS

    Energy Technology Data Exchange (ETDEWEB)

    Jost O.L. Wendt; Gregory E. Ogden; Jennifer Sinclair; Stephanus Budilarto

    2001-09-04

    It is well understood that the stability of axial diffusion flames is dependent on the mixing behavior of the fuel and combustion air streams. Combustion aerodynamic texts typically describe flame stability and transitions from laminar diffusion flames to fully developed turbulent flames as a function of increasing jet velocity. Turbulent diffusion flame stability is greatly influenced by recirculation eddies that transport hot combustion gases back to the burner nozzle. This recirculation enhances mixing and heats the incoming gas streams. Models describing these recirculation eddies utilize conservation of momentum and mass assumptions. Increasing the mass flow rate of either fuel or combustion air increases both the jet velocity and momentum for a fixed burner configuration. Thus, differentiating between gas velocity and momentum is important when evaluating flame stability under various operating conditions. The research efforts described herein are part of an ongoing project directed at evaluating the effect of flame aerodynamics on NO{sub x} emissions from coal fired burners in a systematic manner. This research includes both experimental and modeling efforts being performed at the University of Arizona in collaboration with Purdue University. The objective of this effort is to develop rational design tools for optimizing low NO{sub x} burners. Experimental studies include both cold-and hot-flow evaluations of the following parameters: primary and secondary inlet air velocity, coal concentration in the primary air, coal particle size distribution and flame holder geometry. Hot-flow experiments will also evaluate the effect of wall temperature on burner performance.

  1. Effect of coal slurry on the corrosion of coal-mine equipment

    Institute of Scientific and Technical Information of China (English)

    Zhang Qi; Xie Jingxuan; Zhao Wei; Bai Shasha; Zhong Shiteng; Chu Zhenfeng

    2011-01-01

    The corrosion of coal mine equipment immersed in coal slurry is addressed.The corrosion of low carbon steel samples immersed in coal slurries of different concentrations (80,130,and 180g/L) prepared from coals of different rank (long-flame coal,meager lean coal,and anthracite) and different granularity (0.25-0.5 mm,0.074-0.25 mm,and less than 0.074 mm particle size) was studied by the electrochemical method of polarization curve measurement,controlled potential sweeping,and continuous scanning.The results show that the corrosion rate in an anthracite slurry,where the coal has high coalification,is far greater than corrosion in a long-flame or a meager lean coal slurry.Furthermore the corrosion current,polarization current,and corrosion rate of low carbon steel become larger,and the polarizability becomes smaller,as the coal particle size decreases.The same trend is seen as the concentration of the coal slurry increases.

  2. Oxy-coal Combustion Studies

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, J. [Univ. of Utah, Salt Lake City, UT (United States); Eddings, E. [Univ. of Utah, Salt Lake City, UT (United States); Lighty, J. [Univ. of Utah, Salt Lake City, UT (United States); Ring, T. [Univ. of Utah, Salt Lake City, UT (United States); Smith, P. [Univ. of Utah, Salt Lake City, UT (United States); Thornock, J. [Univ. of Utah, Salt Lake City, UT (United States); Y Jia, W. Morris [Univ. of Utah, Salt Lake City, UT (United States); Pedel, J. [Univ. of Utah, Salt Lake City, UT (United States); Rezeai, D. [Univ. of Utah, Salt Lake City, UT (United States); Wang, L. [Univ. of Utah, Salt Lake City, UT (United States); Zhang, J. [Univ. of Utah, Salt Lake City, UT (United States); Kelly, K. [Univ. of Utah, Salt Lake City, UT (United States)

    2012-01-06

    The objective of this project is to move toward the development of a predictive capability with quantified uncertainty bounds for pilot-scale, single-burner, oxy-coal operation. This validation research brings together multi-scale experimental measurements and computer simulations. The combination of simulation development and validation experiments is designed to lead to predictive tools for the performance of existing air fired pulverized coal boilers that have been retrofitted to various oxy-firing configurations. In addition, this report also describes novel research results related to oxy-combustion in circulating fluidized beds. For pulverized coal combustion configurations, particular attention is focused on the effect of oxy-firing on ignition and coal-flame stability, and on the subsequent partitioning mechanisms of the ash aerosol.

  3. Flame dynamics in a micro-channeled combustor

    Science.gov (United States)

    Hussain, Taaha; Markides, Christos N.; Balachandran, Ramanarayanan

    2015-01-01

    The increasing use of Micro-Electro-Mechanical Systems (MEMS) has generated a significant interest in combustion-based power generation technologies, as a replacement of traditional electrochemical batteries which are plagued by low energy densities, short operational lives and low power-to-size and power-to-weight ratios. Moreover, the versatility of integrated combustion-based systems provides added scope for combined heat and power generation. This paper describes a study into the dynamics of premixed flames in a micro-channeled combustor. The details of the design and the geometry of the combustor are presented in the work by Kariuki and Balachandran [1]. This work showed that there were different modes of operation (periodic, a-periodic and stable), and that in the periodic mode the flame accelerated towards the injection manifold after entering the channels. The current study investigates these flames further. We will show that the flame enters the channel and propagates towards the injection manifold as a planar flame for a short distance, after which the flame shape and propagation is found to be chaotic in the middle section of the channel. Finally, the flame quenches when it reaches the injector slots. The glow plug position in the exhaust side ignites another flame, and the process repeats. It is found that an increase in air flow rate results in a considerable increase in the length (and associated time) over which the planar flame travels once it has entered a micro-channel, and a significant decrease in the time between its conversion into a chaotic flame and its extinction. It is well known from the literature that inside small channels the flame propagation is strongly influenced by the flow conditions and thermal management. An increase of the combustor block temperature at high flow rates has little effect on the flame lengths and times, whereas at low flow rates the time over which the planar flame front can be observed decreases and the time of

  4. Second Law Analysis of Diffusion Flames

    Directory of Open Access Journals (Sweden)

    Yalcin Gogus

    2001-03-01

    Full Text Available The objective of this paper is to investigate the sources of volumetric irreversibilities in both laminar and turbulent diffusion flames. The theoretical background of analysis relies on the local exergy transport equation, which allows the microscopic formulation of the well-known Gouy-Stodola theorem. For laminar reacting flows, the volumetric entropy generation rate expression includes the viscous, thermal, diffusion and chemical components. Their expressions show that the corresponding irreversibilities are uncoupled if the combustion process occurs at constant pressure. The numerical simulation of a methane-air combustion process shows that the thermal, chemical and diffusive irreversibilities represent, in order of enumeration, the predominant irreversibilities in the laminar diffusion reacting flows. In the case of turbulent diffusion flames, the viscous, thermal, diffusion and chemical mean components have to be expressed in accordance with the combustion model. Two combustion models are used: the multi-species approach based on the eddy-break formulation of mean reaction rate, and the assumed probability density function for a conserved scalar that relies on the flame sheet model. For a diffusion methane-air jet flame, the distribution of mean irreversibility components is presented. Taking into account the technical importance of diffusion flames, the analysis could serve to improve the combustion geometry and the flow condition.

  5. Distributed Flames in Type Ia Supernovae

    CERN Document Server

    Aspden, A J; Woosley, S E; 10.1088/0004-637X/710/2/1654

    2011-01-01

    In the distributed burning regime, turbulence disrupts the internal structure of the flame, and so the idea of laminar burning propagated by conduction is no longer valid. The nature of the burning depends on the turbulent Damkohler number (Da), which steadily declines from much greater than one to less that one as the density decreases to a few 10^6 g/cc. Scaling arguments predict that the turbulent flame speed s, normalized by the turbulent intensity u, follows s/u=Da^1/2 for Da1, and that localized excursions to as much as five times u can occur. The lambda-flame speed and width can be predicted based on the turbulence in the star and the turbulent nuclear burning time scale of the fuel. We propose a practical method for measuring these based on the scaling relations and small-scale computationally-inexpensive simulations. This suggests that a simple turbulent flame model can be easily constructed suitable for large-scale distributed supernovae flames.

  6. Enhancement of pulverized coal combustion by plasma technology

    Energy Technology Data Exchange (ETDEWEB)

    Gorokhovski, M.A.; Jankoski, Z.; Lockwood, F.C.; Karpenko, E.I.; Messerle, V.E.; Ustimenko, A.B. [University of Rouen, Rouen (France)

    2007-07-01

    Plasma-assisted pulverized coal combustion is a promising technology for thermal power plants (TPP). This article reports one- and three- dimensional numerical simulations, as well as laboratory and industrial measurements of coal combustion using a plasma-fuel system (PFS). The chemical kinetic and fluid mechanics involved in this technology are analysed. The results show that a PFS, can be used to promote early ignition and enhanced stabilization of a pulverized coal flame. It is shown that this technology, in addition to enhancing the combustion efficiency of the flame, reduces harmful emissions from power coals of all ranks (brown, bituminous, anthracite and their mixtures). Data summarising the experience of 27 pulverized coal boilers in 16 thermal power plants in several countries (Russia, Kazakhstan, Korea, Ukraine, Slovakia, Mongolia and China), embracing steam productivities from 75 to 670 tons per hour (TPH), are presented. Finally, the practical computation of the characteristics of the PFS, as function of coal properties, is discussed.

  7. Igniting the Paralympic Flame

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Deaf-mute Jiang Xintian lights a small cauldron in the hands of wheelchairbound fencer Jin Jing at the Paralympic Flame Lighting Ceremony in Beijing’s symbolic Temple of Heaven on August 28. For nine days until September 6, when the 13th Paralympics opens in Beijing, a total of 850 torchbearers would relay the Paralympic flame along two routes through 11 Chinese provinces,

  8. Pulverized coal and substitute fuels for the cement manufacturing industry

    Energy Technology Data Exchange (ETDEWEB)

    Dobrowsky, F.

    1981-01-01

    This paper comprises an article of general technical interest on coal and its use in the cement industry, plus the scope for using substitute fuels. Discusses coal properties and preparation (crushing). Describes the heating systems of the cement ovens: burners, combustion and parameters governing flame-length. Looks at operation problems connected with heating of the coal: caking, fusing, clinker quality and behaviour of the refractory bricks. Also discusses substitute fuels: type of fuel, scope for utilisation and requisite precautions. 32 refs.

  9. Turbulence-Flame Interactions in Type Ia Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (Authors 1, 2& 3); Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (Author 4); Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (Author 5); Aspden, Andrew J; Aspden, Andrew J.; Bell, John B.; Day, Marc S.; Woosley, Stan E.; Zingale, Mike

    2008-05-27

    The large range of time and length scales involved in type Ia supernovae (SN Ia) requires the use of flame models. As a prelude to exploring various options for flame models, we consider, in this paper, high-resolution three-dimensional simulations of the small-scale dynamics of nuclear flames in the supernova environment in which the details of the flame structure are fully resolved. The range of densities examined, 1 to 8 x 107 g cm-3, spans the transition from the laminar flamelet regime to the distributed burning regime where small scale turbulence disrupts the flame. The use of a low Mach number algorithm facilitates the accurate resolution of the thermal structure of the flame and the inviscid turbulent kinetic energy cascade, while implicitly incorporating kinetic energy dissipation at the grid-scale cutoff. For an assumed background of isotropic Kolmogorov turbulence with an energy characteristic of SN Ia, we find a transition density between 1 and 3 x 107 g cm-3 where the nature of the burning changes ualitatively. By 1 x 107 g cm-3, energy diffusion by conduction and radiation is exceeded, on the flame scale, by turbulent advection. As a result, the effective Lewis Number approaches unity. That is, the flame resembles a laminar flame, but is turbulently broadened with an effective diffusion coefficient, D_T \\sim u' l, where u' is the turbulent intensity and l is the integral scale. For the larger integral scales characteristic of a real supernova, the flame structure is predicted to become complex and unsteady. Implications for a possible transition to detonation are discussed.

  10. Laminar dust flames in a reduced-gravity environment

    Science.gov (United States)

    Goroshin, Samuel; Tang, Francois-David; Higgins, Andrew J.; Lee, John H. S.

    2011-04-01

    The propagation of laminar dust flames in suspensions of iron in gaseous oxidizers was studied in a low-gravity environment onboard a parabolic flight aircraft. The reduction of buoyancy-induced convective flows and particle settling permitted the measurement of fundamental combustion parameters, such as the burning velocity and the flame quenching distance over a wide range of particle sizes and in different gaseous mixtures. Experimentally measured flame speeds and quenching distances were found in good agreement with theoretical predictions of a simplified analytical model that assumes particles burning in a diffusive mode. However, the comparison of flame speeds in oxygen-argon and oxygen-helium iron suspensions indicates the possibility that fine micron-sized particles burn in the kinetic mode. Furthermore, when the particle spacing is large compared to the scale of the reaction zone, a theoretical analysis suggests the existence of a new so-called discrete flame propagation regime. Discrete flames are strongly dependent on particle density fluctuations and demonstrate directed percolation behavior near flame propagation limits. The experimental observation of discrete flames in particle suspensions will require low levels of gravity over extended periods available only on orbital platforms.

  11. Investigations of two-phase flame propagation under microgravity conditions

    Science.gov (United States)

    Gokalp, Iskender

    2016-07-01

    uniformly distributed. Ethanol-air mixtures are used and the experiments are performed under reduced gravity conditions in the Airbus A310 ZERO-G of the CNES, during which a 10-2g gravity level is achieved. The experiments are conducted in a pressure-release type dual chamber which consists of a spherical combustion chamber of 1 L which is centered in a high pressure chamber of 11 L. Propagating flames under various mixture, droplet size and pressure conditions are investigated with various optical techniques. The collected flame images and the deduced flame propagation velocities enabled to establish various flame propagation and cellular instability regimes, mainly depending on the droplet size and droplet density. The experiments also permitted comparisons with gaseous flames having the same global equivalence ratio as the two-phase flames, therefore allowing analyzing clearly the role of the presence of the droplets in the flame propagation process.

  12. Real Time Flame Monitoring of Gasifier and Injectors

    Energy Technology Data Exchange (ETDEWEB)

    Zelepouga, Serguei; Saveliev, Alexei

    2011-12-31

    This project is a multistage effort with the final goal to develop a practical and reliable nonintrusive gasifier injector monitor to assess burner wear and need for replacement. The project team included the National Energy Technology Laboratory (NETL), Gas Technology Institute (GTI), North Carolina State University, and ConocoPhillips. This report presents the results of the sensor development and testing initially at GTI combustion laboratory with natural gas flames, then at the Canada Energy Technology Center (CANMET), Canada in the atmospheric coal combustor as well as in the pilot scale pressurized entrained flow gasifier, and finally the sensor capabilities were demonstrated at the Pratt and Whitney Rocketdyne (PWR) Gasifier and the Wabash River Repowering plant located in West Terre Haute, IN. The initial tests demonstrated that GTI gasifier sensor technology was capable of detecting shape and rich/lean properties of natural gas air/oxygen enriched air flames. The following testing at the Vertical Combustor Research Facility (VCRF) was a logical transition step from the atmospheric natural gas flames to pressurized coal gasification environment. The results of testing with atmospheric coal flames showed that light emitted by excited OH* and CH* radicals in coal/air flames can be detected and quantified. The maximum emission intensities of OH*, CH*, and black body (char combustion) occur at different axial positions along the flame length. Therefore, the excitation rates of CH* and OH* are distinct at different stages of coal combustion and can be utilized to identify and characterize processes which occur during coal combustion such as devolatilization, char heating and burning. To accomplish the goals set for Tasks 4 and 5, GTI utilized the CANMET Pressurized Entrained Flow Gasifier (PEFG). The testing parameters of the PEFG were selected to simulate optimum gasifier operation as well as gasifier conditions normally resulting from improper operation or

  13. An experimental investigation of the interaction between a Karman vortex street and a premixed laminar flame

    Science.gov (United States)

    Namer, I.

    1980-12-01

    The interaction of a premixed C2H4-air flame with a Karman vortex street was studied. Laser Doppler anemometry was used for velocity measurements and Rayleigh scattering was used to measure total gas density. A reference hot wire was used to enable phase-locked ensemble averaging to be performed on the data. The velocity measurements for vortex shedding cylinder Reynolds numbers indicated that the vortex street and, hence, the flow field upstream of the flame is deflected by the flame. This is due to the pressure drop across the flame which is necessary to accelerate the flow behind the flame. The vortices were not observed behind the flame. The combination of dilation and increased dissipation consumed the vortices. Density statistics obtained from Rayleigh scattering measurements were compared with predictions by the Bray-Moss-Libby (B-M-L) model which neglects intermediate states. Density fluctuations were overpredicted by the B-M-L model by a small amount.

  14. Monitoring Atmospheric Transmission with FLAME

    Science.gov (United States)

    Zimmer, Peter C.; McGraw, J. T.; Zirzow, D. C.; Koppa, M.; Buttler-Pena, K.

    2014-01-01

    Calibration of ground-based observations in the optical and near-infrared requires precise and accurate understanding of atmospheric transmission, at least as precise and accurate as that required for the spectral energy distributions of science targets. Traditionally this has used the Langley extrapolation method, observing targets and calibrators over a range of airmass and extrapolating to zero airmass by assuming a plane-parallel homogeneous atmosphere. The technique we present uses direct measurements of the atmosphere to derive the transmission along the line of sight to science targets at a few well-chosen wavelengths. The Facility Lidar Atmospheric Monitor of Extinction (FLAME) is a 0.5m diameter three Nd:YAG wavelength (355nm, 532nm & 1064nm) elastic backscatter lidar system. Laser pulses are transmitted into the atmosphere in the direction of the science target. Photons scattered back toward the receiver by molecules, aerosols and clouds are collected and time-gated so that the backscatter intensity is measured as a function of range to the scattering volume. The system is housed in a mobile calibration lab, which also contains auxiliary instrumentation to provide a NIST traceable calibration of the transmitted laser power and receiver efficiency. FLAME was designed to create a million photons per minute signal from the middle stratosphere, where the atmosphere is relatively calm and dominated by molecules of the well-mixed atmosphere (O2 & N2). Routine radiosonde measurements of the density at these altitudes constrain the scattering efficiency in this region and, combined with calibration of the transmitter and receiver, the only remaining unknown quantity is the two-way transmission to the stratosphere. These measurements can inform atmospheric transmission models to better understand the complex and ever-changing observatory radiative transfer environment. FLAME is currently under active development and we present some of our ongoing measurements.

  15. A non-adiabatic flamelet progress–variable approach for LES of turbulent premixed flames

    NARCIS (Netherlands)

    Cecere, Donato; Giacomazzi, Eugenio; Picchia, Franca R.; Arcidiacono, Nunzio; Donato, Filippo; Verzicco, Roberto

    2011-01-01

    A progress variable/flame surface density/probability density function method has been employed for a Large Eddy Simulation of a CH4/Air turbulent premixed bluff body flame. In particular, both mean and variance of the progress variable are transported and subgrid spatially filtered gradient contrib

  16. Numerical modelling of ion transport in flames

    KAUST Repository

    Han, Jie

    2015-10-20

    This paper presents a modelling framework to compute the diffusivity and mobility of ions in flames. The (n, 6, 4) interaction potential is adopted to model collisions between neutral and charged species. All required parameters in the potential are related to the polarizability of the species pair via semi-empirical formulas, which are derived using the most recently published data or best estimates. The resulting framework permits computation of the transport coefficients of any ion found in a hydrocarbon flame. The accuracy of the proposed method is evaluated by comparing its predictions with experimental data on the mobility of selected ions in single-component neutral gases. Based on this analysis, the value of a model constant available in the literature is modified in order to improve the model\\'s predictions. The newly determined ion transport coefficients are used as part of a previously developed numerical approach to compute the distribution of charged species in a freely propagating premixed lean CH4/O2 flame. Since a significant scatter of polarizability data exists in the literature, the effects of changes in polarizability on ion transport properties and the spatial distribution of ions in flames are explored. Our analysis shows that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect that the modelling framework proposed here will benefit future efforts in modelling the effect of external voltages on flames. Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/13647830.2015.1090018. © 2015 Taylor & Francis.

  17. Comparative analysis for performance of brown coal combustion in a vortex furnace with improved design

    Science.gov (United States)

    Krasinsky, D. V.

    2016-09-01

    Comparative study of 3D numerical simulation of fluid flow and coal-firing processes was applied for flame combustion of Kansk-Achinsk brown coal in a vortex furnace of improved design with bottom injection of secondary air. The analysis of engineering performance of this furnace was carried out for several operational modes as a function of coal grinding fineness and coal input rate. The preferable operational regime for furnace was found.

  18. Flaming on YouTube

    NARCIS (Netherlands)

    Moor, Peter J.; Heuvelman, A.; Verleur, R.

    2010-01-01

    In this explorative study, flaming on YouTube was studied using surveys of YouTube users. Flaming is defined as displaying hostility by insulting, swearing or using otherwise offensive language. Three general conclusions were drawn. First, although many users said that they themselves do not flame,

  19. Flaming on YouTube

    NARCIS (Netherlands)

    Moor, Peter J.; Heuvelman, Ard; Verleur, Ria

    2010-01-01

    In this explorative study, flaming on YouTube was studied using surveys of YouTube users. Flaming is defined as displaying hostility by insulting, swearing or using otherwise offensive language. Three general conclusions were drawn. First, although many users said that they themselves do not flame,

  20. Flame kernel generation and propagation in turbulent partially premixed hydrocarbon jet

    KAUST Repository

    Mansour, Mohy S.

    2014-04-23

    Flame development, propagation, stability, combustion efficiency, pollution formation, and overall system efficiency are affected by the early stage of flame generation defined as flame kernel. Studying the effects of turbulence and chemistry on the flame kernel propagation is the main aim of this work for natural gas (NG) and liquid petroleum gas (LPG). In addition the minimum ignition laser energy (MILE) has been investigated for both fuels. Moreover, the flame stability maps for both fuels are also investigated and analyzed. The flame kernels are generated using Nd:YAG pulsed laser and propagated in a partially premixed turbulent jet. The flow field is measured using 2-D PIV technique. Five cases have been selected for each fuel covering different values of Reynolds number within a range of 6100-14400, at a mean equivalence ratio of 2 and a certain level of partial premixing. The MILE increases by increasing the equivalence ratio. Near stoichiometric the energy density is independent on the jet velocity while in rich conditions it increases by increasing the jet velocity. The stability curves show four distinct regions as lifted, attached, blowout, and a fourth region either an attached flame if ignition occurs near the nozzle or lifted if ignition occurs downstream. LPG flames are more stable than NG flames. This is consistent with the higher values of the laminar flame speed of LPG. The flame kernel propagation speed is affected by both turbulence and chemistry. However, at low turbulence level chemistry effects are more pronounced while at high turbulence level the turbulence becomes dominant. LPG flame kernels propagate faster than those for NG flame. In addition, flame kernel extinguished faster in LPG fuel as compared to NG fuel. The propagation speed is likely to be consistent with the local mean equivalence ratio and its corresponding laminar flame speed. Copyright © Taylor & Francis Group, LLC.

  1. Flame Stretch Analysis in Diffusion Flames with Inert Gas

    Institute of Scientific and Technical Information of China (English)

    Ay Su; Ying-Chieh Liu

    2001-01-01

    Experimental investigations of impinging flame with fuel mixed with non-reaction gas were conducted.According to the observations of combustion test and temperature measurement, the non-reaction gas might dilute the local concentration of fuel in the diffusion process. The shape of the flame was symmetrical due to the flame stretch force. Results show that the conical flame might be de-structured by the addition of inert gas in pure methane fuel. The impinging flame became shorter and bluer as nitrogen was added to the fuel. The conditions of N2/CH4 equal to 1/2 and 1/1 show a wider plane in the YZ plane. The effect of inert gas overcomes the flame stretch and destroys the symmetrical column flame as well as the cold flow. Nitrogen addition also enhances the diffusion rate and combustion efficiency.

  2. Propagation Limits of High Pressure Cool Flames

    Science.gov (United States)

    Ju, Yiguang

    2016-11-01

    The flame speeds and propagation limits of premixed cool flames at elevated pressures with radiative heat loss are numerically modelled using dimethyl ether mixtures. The primary focus is paid on the effects of pressure, mixture dilution, flame size, and heat loss on cool flame propagation. The results showed that cool flames exist on both fuel lean and fuel rich sides and thus dramatically extend the lean and rich flammability limits. There exist three different flame regimes, hot flame, cool flame, and double flame. A new flame flammability diagram including both cool flames and hot flames is obtained at elevated pressure. The results show that pressure significantly changes cool flame propagation. It is found that the increases of pressure affects the propagation speeds of lean and rich cool flames differently due to the negative temperature coefficient effect. On the lean side, the increase of pressure accelerates the cool flame chemistry and shifts the transition limit of cool flame to hot flame to lower equivalence ratio. At lower pressure, there is an extinction transition from hot flame to cool flame. However, there exists a critical pressure above which the cool flame to hot flame transition limit merges with the lean flammability limit of the hot flame, resulting in a direct transition from hot flame to cool flame. On the other hand, the increase of dilution reduces the heat release of hot flame and promotes cool flame formation. Moreover, it is shown that a smaller flame size and a higher heat loss also extend the cool flame transition limit and promote cool flame formation.

  3. CoFlame: A refined and validated numerical algorithm for modeling sooting laminar coflow diffusion flames

    Science.gov (United States)

    Eaves, Nick A.; Zhang, Qingan; Liu, Fengshan; Guo, Hongsheng; Dworkin, Seth B.; Thomson, Murray J.

    2016-10-01

    Mitigation of soot emissions from combustion devices is a global concern. For example, recent EURO 6 regulations for vehicles have placed stringent limits on soot emissions. In order to allow design engineers to achieve the goal of reduced soot emissions, they must have the tools to so. Due to the complex nature of soot formation, which includes growth and oxidation, detailed numerical models are required to gain fundamental insights into the mechanisms of soot formation. A detailed description of the CoFlame FORTRAN code which models sooting laminar coflow diffusion flames is given. The code solves axial and radial velocity, temperature, species conservation, and soot aggregate and primary particle number density equations. The sectional particle dynamics model includes nucleation, PAH condensation and HACA surface growth, surface oxidation, coagulation, fragmentation, particle diffusion, and thermophoresis. The code utilizes a distributed memory parallelization scheme with strip-domain decomposition. The public release of the CoFlame code, which has been refined in terms of coding structure, to the research community accompanies this paper. CoFlame is validated against experimental data for reattachment length in an axi-symmetric pipe with a sudden expansion, and ethylene-air and methane-air diffusion flames for multiple soot morphological parameters and gas-phase species. Finally, the parallel performance and computational costs of the code is investigated.

  4. Formation and retention of methane in coal

    Energy Technology Data Exchange (ETDEWEB)

    Hucka, V.J.; Bodily, D.M.; Huang, H.

    1992-05-15

    The formation and retention of methane in coalbeds was studied for ten Utah coal samples, one Colorado coal sample and eight coal samples from the Argonne Premium Coal Sample Bank.Methane gas content of the Utah and Colorado coals varied from zero to 9 cm{sup 3}/g. The Utah coals were all high volatile bituminous coals. The Colorado coal was a gassy medium volatile bituminous coal. The Argonne coals cover a range or rank from lignite to low volatile bituminous coal and were used to determine the effect of rank in laboratory studies. The methane content of six selected Utah coal seams and the Colorado coal seam was measured in situ using a special sample collection device and a bubble desorbometer. Coal samples were collected at each measurement site for laboratory analysis. The cleat and joint system was evaluated for the coal and surrounding rocks and geological conditions were noted. Permeability measurements were performed on selected samples and all samples were analyzed for proximate and ultimate analysis, petrographic analysis, {sup 13}C NMR dipolar-dephasing spectroscopy, and density analysis. The observed methane adsorption behavior was correlated with the chemical structure and physical properties of the coals.

  5. Numerical Simulation of Microgravity Flame Spread Over Solid Combustibles

    Institute of Scientific and Technical Information of China (English)

    JIANGXi; FANWeicheng

    1995-01-01

    A computational model of three-dimensional,time-dependent flame spread in microgravity environment is presented.THe solid is assumed to be a thermally-thin,pyrolysing cellulosic sheet.The gas phase model includes the full Navier-Stokes equations with density and pressure variations and six-flus model of radiation heat transfer,The solid phase model consists of continuity and energy equations whose solution provides boundary conditions for the gas phase equatons.In the numerical procedure,the gas-and solid -phase equations are solved separately and iteratively at each time step.Predictions have been made of flame spreas in slow forced flow under gravitational acceleration normal to fuel surface and flame spread in a quiescent environment in an enclosed chamber under gravitational acceleration parallel to fuel surface.Numerical simulations show that,under microgravity,slow-flow conditions,flame spread process is highly unsteady with the upstream flame spreads faster than the downstream flame after a period of ignition,It has also been shown that the level of microgravity has a significant effect on the flame spread process.

  6. "Magic Eraser" Flame Tests

    Science.gov (United States)

    Landis, Arthur M.; Davies, Malonne I.; Landis, Linda

    2009-01-01

    Cleaning erasers are used to support methanol-fueled flame tests. This safe demonstration technique requires only small quantities of materials, provides clean colors for up to 45 seconds, and can be used in the classroom or the auditorium. (Contains 1 note.)

  7. Plasma-fuel systems for environment and economy indexes of pulverized coal incineration and gasification improvement

    Energy Technology Data Exchange (ETDEWEB)

    E. Karpenko; V. Messerle; A. Ustimenko [United Power System of Russia, Gusinoozersk (Russian Federation). Branch Centre of Plasma-Power Technologies of Russian J.S.Co.

    2003-07-01

    Coal is one of the main energy resources. To improve efficiency of coal incineration new plasma-energy technologies are developing. Steam-productivity 75t/h 670t/h boilers were tested for their starting up by plasma ignition of pulverized coal and flame stabilization. Laboratory (coal consumption to 20kg/h) and pilot (coal consumption 300kg/h and 32000kg/h) plasma gasification experiments are given. Plasma air and steam gasification of coal with its mineral mass utilization is studied. 8 refs., 10 figs., 4 tabs.

  8. Application of rubber anti-aging agents in preventing coal spontaneous combustion

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S.; Zhang, R.; Yang, Y.; Yang, H.; Fan, X.

    1999-07-01

    Based on the mechanism of rubber aging and action of anti-aging agents in preventing rubber aging, the free radical chain reaction mechanism of the oxidation of coal was discussed and compound stopping agents were introduced in the paper. The rubber anti-aging agents of aromatic amine are selected for the stopping agent of preventing coal spontaneous combustion. The stopping action of these anti-aging agents and common inorganic salt stopping agents for long flame coal in Gengcun Colliery, Yima city, Henan province in China is researched. The anti-aging agents for the long flame coal have the prominent efficiency and fine stopping action in later period, and inorganic stopping agents containing magnesium chloride salt for the long flame coal have the prominent efficiency in early period, but the compound stopping agents that are composed of the rubber anti-aging agents and magnesium chloride have longer life.

  9. Turbulence-Flame Interactions in Type Ia Supernovae

    CERN Document Server

    Aspden, A J; Day, M S; Woosley, S E; Zingale, M

    2008-01-01

    The large range of time and length scales involved in type Ia supernovae (SN Ia) requires the use of flame models. As a prelude to exploring various options for flame models, we consider, in this paper, high-resolution three-dimensional simulations of the small-scale dynamics of nuclear flames in the supernova environment in which the details of the flame structure are fully resolved. The range of densities examined, 1 to $8 \\times 10^7$ g cm$^{-3}$, spans the transition from the laminar flamelet regime to the distributed burning regime where small scale turbulence disrupts the flame. The use of a low Mach number algorithm facilitates the accurate resolution of the thermal structure of the flame and the inviscid turbulent kinetic energy cascade, while implicitly incorporating kinetic energy dissipation at the grid-scale cutoff. For an assumed background of isotropic Kolmogorov turbulence with an energy characteristic of SN Ia, we find a transition density between 1 and $3 \\times 10^7$ g cm$^{-3}$ where the na...

  10. Utilisation of coal for energy production in fuel cells

    Directory of Open Access Journals (Sweden)

    Dudek Magdalena

    2016-01-01

    Full Text Available In this paper a brief characterization of fuel cell technology and its possible application in sustainable energy development was described. Special attention was paid to direct carbon fuel cell technology. The direct carbon fuel cell is an electrochemical device which directly converts the chemical energy of carbonaceous based fuel into electricity without ‘flame burning’. The electrical efficiency of a DCFC is indeed very high (in practice exceeding 80%, and the product of conversion consists of almost pure CO2, eliminating the most expensive step of sequestration: the separation of carbon from flue gases. In this paper the process of electrochemical oxidation of carbon particles on the surface of oxide electrolytes at 8% mol Y2O3 in ZrO2 (8YSZ as well as cermet anode Ni-8YSZ was analysed. The graphite, carbon black powders were considered as reference solid fuels for coal samples. It was found that the main factors contributing to the electrochemical reactivity of carbon particles is not only the high carbon content in samples but also structural disorder. It was found that structurally disordered carbon-based materials are the most promising solid fuels for direct carbon solid oxide fuel cells. Special impact was placed on the consideration of coal as possible solid fuels for DC-SOFC. Statistical and economic analyses show that in the coming decades, in developing countries such as China, India, and some EU countries, coal-fuelled power plants will maintain their strong position in the power sector due to their reliability and low costs as well as the large reserves of coal and lignite in the world. Coal is mined in politically stable areas, which guarantees its easy and safe purchase and transport. The impact of the physiochemical properties of raw and purified coal on the performance of the DC-SOFC was studied. An analysis of the stability of electrical parameters was performed for a DC-SOFC operating under a load over an extended

  11. Modeling and simulation of axisymmetric stagnation flames

    Science.gov (United States)

    Sone, Kazuo

    Laminar flame modeling is an important element in turbulent combustion research. The accuracy of a turbulent combustion model is highly dependent upon our understanding of laminar flames and their behavior in many situations. How much we understand combustion can only be measured by how well the model describes and predicts combustion phenomena. One of the most commonly used methane combustion models is GRI-Mech 3.0. However, how well the model describes the reacting flow phenomena is still uncertain even after many attempts to validate the model or quantify uncertainties. In the present study, the behavior of laminar flames under different aerodynamic and thermodynamic conditions is studied numerically in a stagnation-flow configuration. In order to make such a numerical study possible, the spectral element method is reformulated to accommodate the large density variations in methane reacting flows. In addition, a new axisymmetric basis function set for the spectral element method that satisfies the correct behavior near the axis is developed, and efficient integration techniques are developed to accurately model axisymmetric reacting flow within a reasonable amount of computational time. The numerical method is implemented using an object-oriented programming technique, and the resulting computer program is verified with several different verification methods. The present study then shows variances with the commonly used GRI-Mech 3.0 chemical kinetics model through a direct simulation of laboratory flames that allows direct comparison to experimental data. It is shown that the methane combustion model based on GRI-Mech 3.0 works well for methane-air mixtures near stoichiometry. However, GRI-Mech 3.0 leads to an overprediction of laminar flame speed for lean mixtures and an underprediction for rich mixtures. This result is slightly different from conclusion drawn in previous work, in which experimental data are compared with a one-dimensional numerical solutions

  12. Influence of Coal Quality on Combustion Performance

    DEFF Research Database (Denmark)

    Lans, Robert Pieter Van Der; Glarborg, Peter; Dam-Johansen, Kim

    1998-01-01

    Three coals have been fired in a tangentially and an opposed fired full scale power plant (about 400 MWe) and in a pilot scale test rig (160 kWt) in order to investigate the influence of coal quality on nitrogen oxide (NO) formation and unburned carbon in relation to furnace design. In-flame and ......Three coals have been fired in a tangentially and an opposed fired full scale power plant (about 400 MWe) and in a pilot scale test rig (160 kWt) in order to investigate the influence of coal quality on nitrogen oxide (NO) formation and unburned carbon in relation to furnace design. In......-flame and furnace gas temperatures have been measured, and substantial differences in temperature between the coals were observed in the full scale furnaces. Identical trends in NO emission as a function of coal type were obtained for the three furnaces. The emissions correlated well with the high temperature...... volatile yield obtained from heated wire mesh analysis. Under air staging conditions the pilot scale test rig was able to reproduce quantitatively the amount of NO from the tangentially fired plant, which operates with over fire air. This is probably due to the relatively small influence of the near burner...

  13. Raw Coal Density Affected to Surface Zeta Potential of Muddy and Slime Particle%原煤密度对泥化及煤泥颗粒表面ξ电位的影响

    Institute of Scientific and Technical Information of China (English)

    赵晴; 闵凡飞; 刘令云; 李宏亮

    2011-01-01

    The muddy experiment on 50 -0.5 mm different density raw coal from Dingji Coal Preparation Plant of Huainan Mining Area was conducted. The X-ray diffractor and the electrophoresis experiment was individually applied to measure the raw coal mineral composition and the zeta potential on the micro particle surface of the slime. The results showed that the main mineral composition of the raw coal to be prepared would be including quartz, kaolinite, green mudstone and others. The muddy rate of the high density and medium density raw coal was high. In the muddy slime of the +1. 60 g/cmJ raw coal, the -0. 045 mm particles would be the majority and the -0. 025 mm micro particles would be over 90%. With the raw coal density increased and the slime particle reduced, the zeta potential on the micro particle surface of the muddy slime would be reduced in potential. The water hardness, the soluble salt in the raw coal and the particle surface property would have important influence to the zeta potential occurred on the slime micro particle. The zeta potential increased on the slime micro particle surface would cause the particles in the slime water in more stable dispersed state.%对淮南矿区丁集选煤厂50~0.5 mm不同密度级原煤进行了泥化试验,采用X-射线衍射 仪和电泳试验分别对原煤矿物组成和煤泥微细颗粒表面ξ电位进行了测定.结果表明:入选原煤中主要矿物成分有石英、高岭石、绿泥石等;高密度和中间密度级原煤泥化率大,+1.60g/cm3原煤泥化煤泥中-0.045 mm颗粒最多,其中约90%以上为-0.025 mm的微细颗粒;随着原煤密度的增大和煤泥粒度的减小,泥化煤泥微细颗粒表面ξ电位呈减小趋势,水的硬度、原煤中可溶性盐及颗粒表面性质对煤泥微细颗粒ξ电位产生重要影响,微细煤泥颗粒表面ξ电位增大会导致其在煤泥水中处于更加稳定的分散状态.

  14. Flame Retardant Epoxy Resins

    Science.gov (United States)

    Thompson, C. M.; Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Lyon, R. E.

    2004-01-01

    As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed.

  15. Antimony: a flame fighter

    Science.gov (United States)

    Wintzer, Niki E.; Guberman, David E.

    2015-01-01

    Antimony is a brittle, silvery-white semimetal that conducts heat poorly. The chemical compound antimony trioxide (Sb2O3) is widely used in plastics, rubbers, paints, and textiles, including industrial safety suits and some children’s clothing, to make them resistant to the spread of flames. Also, sodium antimonate (NaSbO3) is used during manufacturing of high-quality glass, which is found in cellular phones.

  16. Dynamics of unconfined spherical flames

    CERN Document Server

    Leblanc, Louis; Dennis, Kadeem; Zhe,; Liang,; Radulescu, Matei I

    2012-01-01

    Using the soap bubble technique, we visualize the dynamics of unconfined hydrogen-air flames using high speed schlieren video. We show that for sufficiently weak mixtures, i.e., low flame speeds, buoyancy effects become important. Flame balls of a critical dimension begin to rise. The experiments are found in very good agreement with the scaling laws proposed by Zingale and Dursi. We report the results in a fluid dynamics video.

  17. Soot Deposit Properties in Practical Flames

    Energy Technology Data Exchange (ETDEWEB)

    Preciado, Ignacio [University of Utah; Eddings, Eric G. [University of Utah; Sarofim, Adel F. [University of Utah; Dinwiddie, Ralph Barton [ORNL; Porter, Wallace D [ORNL; Lance, Michael J [ORNL

    2009-01-01

    Soot deposition from hydrocarbon flames was investigated in order to evaluate the evolution of the deposits during the transient process of heating an object that starts with a cold metal surface that is exposed to a flame. The study focused on the fire/metal surface interface and the critical issues associated with the specification of the thermal boundaries at this interface, which include the deposition of soot on the metal surface, the chemical and physical properties of the soot deposits and their subsequent effect on heat transfer to the metal surface. A laboratory-scale device (metallic plates attached to a water-cooled sampling probe) was designed for studying soot deposition in a laminar ethylene-air premixed flame. The metallic plates facilitate the evaluation of the deposition rates and deposit characteristics such as deposit thickness, bulk density, PAH content, deposit morphology, and thermal properties, under both water-cooled and uncooled conditions. Additionally, a non-intrusive Laser Flash Technique (in which the morphology of the deposit is not modified) was used to estimate experimental thermal conductivity values for soot deposits as a function of deposition temperature (water-cooled and uncooled experiments), location within the flame and chemical characteristics of the deposits. Important differences between water-cooled and uncooled surfaces were observed. Thermophoresis dominated the soot deposition process and enhanced higher deposition rates for the water-cooled experiments. Cooler surface temperatures resulted in the inclusion of increased amounts of condensable hydrocarbons in the soot deposit. The greater presence of condensable material promoted decreased deposit thicknesses, larger deposit densities, different deposit morphologies, and higher thermal conductivities.

  18. Monte Carlo Simulation of Nanoparticle Encapsulation in Flames

    Science.gov (United States)

    Sun, Z.; Huertas, J. I.; Axelbaum, R. L.

    1999-01-01

    Gas-phase combustion (flame) synthesis has been an essential industrial process for producing large quantities of powder materials such as carbon black, titanium dioxide, and silicon dioxide. Flames typically produce simple oxides, with carbon black being the noted exception because the oxides of carbon are gaseous and are easily separated from the particulate matter that is formed during fuel pyrolysis. Furthermore, the powders produced in flames are usually agglomerated, nanometer-sized particles (nanoparticles). This composition and morphology is acceptable for many applications. However, the present interest in nanoparticles for advanced materials application has led to efforts to employ flames for the synthesis of unagglomerated nanoparticles (2 to 100 nm) of metals and non-oxide ceramics. Sodium-halide chemistry has proven to be viable for producing metals and non-oxide ceramics in flames. Materials that have been produced to date include Si (Calcote and Felder, 1993), TiN, TiB2, TiC, TiSi2, SiC, B4C (Glassman et al, 1993) Al, W, Ti, TiB2, AlN, and W-Ti and Al-AlN composites (DuFaux and Axelbaum, 1995, Axelbaum et al 1996,1997). Many more materials are possible. The main challenge that faces application of flame synthesis for advanced materials is overcoming formation of agglomerates in flames (Brezinsky, 1997). The high temperatures and high number densities in the flame environment favor the formation of agglomerates. Agglomerates must be avoided for many reasons. For example, when nanopowders are consolidated, agglomerates have a deleterious effect on compaction density, leading to voids in the final part. Efforts to avoid agglomeration in flames without substantially reducing particle number density and, consequently, production rate, have had limited success. Another critical challenge that faces all synthesis routes for nanopowders is ensuring that the powders are high purity and that the process is scaleable. Though the containerless, high temperature

  19. Application of Fourier-transform infrared (FT-ir) spectroscopy to in-situ studies of coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ottesen, D K; Thorne, L R

    1982-04-01

    The feasibility of using Fourier-transform infrared (FT-ir) spectroscopy for in situ measurement of gas phase species concentrations and temperature during coal combustion is examined. This technique is evaluated in terms of its potential ability to monitor several important chemical and physical processes which occur in pulverized coal combustion. FT-ir absorption measurements of highly sooting, gaseous hydrocarbon/air flames are presented to demonstrate the fundamental usefulness of the technique for in situ detection of gas phase temperatures and species concentrations in high temperature combustion environments containing coal, char, mineral matter and soot particles. Preliminary results for coal/gaseous fuel/air flames are given.

  20. Influence of Process Parameters on Coal Combustion Performance

    DEFF Research Database (Denmark)

    Lans, Robert Pieter Van Der

    The objective of this study is to improve the understanding of nitrogen oxide formation and carbon burnout during the combustion of pulverized coal, and to contribute to addressing the potential of chemical engineering models for the prediction of furnace temperatures, NO emissions and the amount...... of carbon in ash. To this purpose, the effect of coal quality on NO and burnout has been investigated experimentally, a radiation heat balance has been developed based on simple chemical engineering methodology, and a mixing study has been conducted in order to describe the near burner macro mixing in terms...... with self-sustaining flames, while extensions are made to full scale boilers and furnace modeling. Since coal combustion and flame aerodynamics are reviewed elsewhere, these phenomena are only treated briefly. The influence of coal type and process conditions on NO formation and carbon burnout has been...

  1. Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

    Science.gov (United States)

    This paper/presentation is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practicall...

  2. Soot, organics and ultrafine ash from air- and oxy-fired coal combustion

    Science.gov (United States)

    This paper is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practically relevant s...

  3. COAL PARTICLE FLOW PATTERNS FOR O2 ENRICHED, LOW NOx BURNERS

    Energy Technology Data Exchange (ETDEWEB)

    Jennifer L. Sinclair

    2001-09-30

    Over the past year, the hot flow studies have focused on the validation of a novel 2M near-flame combustion furnace. The 2M furnace was specifically designed to investigate burner aerodynamics and flame stability phenomena. Key accomplishments include completion of coal & oxygen mass balance calculations and derivation of emission conversion equations, upgrade of furnace equipment and flame safety systems, shakedown testing and partial completion of a parametric flame stability study. These activities are described in detail below along with a description of the 2M furnace and support systems.

  4. Studies of Methane Counterflow Flames at Low Pressures

    Science.gov (United States)

    Burrell, Robert Roe

    Methane is the smallest hydrocarbon molecule, the fuel most widely studied in fundamental flame structure studies, and a major component of natural gas. Despite many decades of research into the fundamental chemical kinetics involved in methane oxidation, ongoing advancements in research suggest that more progress can be made. Though practical combustors of industrial and commercial significance operate at high pressures and turbulent flow conditions, fundamental understanding of combustion chemistry in flames is more readily obtained for low pressure and laminar flow conditions. Measurements were performed from 1 to 0.1 atmospheres for premixed methane/air and non-premixed methane-nitrogen/oxygen flames in a counterflow. Comparative modeling with quasi-one-dimensional strained flame codes revealed bias-induced errors in measured velocities up to 8% at 0.1 atmospheres due to tracer particle phase velocity slip in the low density gas reacting flow. To address this, a numerically-assisted correction scheme consisting of direct simulation of the particle phase dynamics in counterflow was implemented. Addition of reactions describing the prompt dissociation of formyl radicals to an otherwise unmodified USC Mech II kinetic model was found to enhance computed flame reactivity and substantially improve the predictive capability of computed results for measurements at the lowest pressures studied. Yet, the same modifications lead to overprediction of flame data at 1 atmosphere where results from the unmodified USC Mech II kinetic mechanism agreed well with ambient pressure flame data. The apparent failure of a single kinetic model to capture pressure dependence in methane flames motivates continued skepticism regarding the current understanding of pressure dependence in kinetic models, even for the simplest fuels.

  5. Mode Selection in Flame-Vortex driven Combustion Instabilities

    KAUST Repository

    Speth, Ray

    2011-01-04

    In this paper, we investigate flame-vortex interaction in a lean premixed, laboratory scale, backward-facing step combustor. Two series of tests were conducted, using propane/hydrogen mixtures and carbon monoxide/hydrogen mixtures as fuels, respectively. Pressure measurements and high speed particle imaging velocimetry (PIV) were employed to generate pressure response curves as well as the images of the velocity field and the flame brush. We demonstrate that the step combustor exhibits several operating modes depending on the inlet conditions and fuel composition, characterized by the amplitude and frequency of pressure oscillations along with distinct dynamic flame shapes. We propose a model in which the combustor\\'s selection of the acoustic mode is governed by a combustion-related time delay inversely proportional to the flame speed. Our model predicts the transition between distinct operating modes. We introduce non-dimensional parameters characterizing the flame speed and stretch rate, and develop a relationship between these quantities at the operating conditions corresponding to each mode transition. Based on this relationship, we show that numerically-calculated density-weighted strained flame speed can be used to collapse the combustion dynamics data over the full range of conditions (inlet temperature, fuel composition, and equivalence ratio). Finally, we validate our strain flame based model by measuring the strain rate using the flame image and the velocity field from the PIV measurement. Our results show that the measured strain rates lie in the same range as the critical values at the transitions among distinct modes as those predicted by our model.

  6. Development of tensile test method for high-density coal under carbonization; Kojuten mitsudo sekitan no netsukan hippari shikenho no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, A.; Ueki, M.; Aoki, H.; Miura, T. [Tohoku University, Sendai (Japan); Kato, K.; Fukuda, K. [Nippon Steel Corp., Tokyo (Japan)

    1998-05-01

    Since it is expected that the consumption of non-caking and slightly caking coals will increase and that particulates will have to be controlled with more severity, lumping in hot conditions is being studied as a next-generation technology for coke production. For the study of the augmentation of coke strength, the strength of the material has to be measured while it is in the semi-coke temperature zone. To fulfill the purpose, a method of tensile test is developed for densely packed coal in the carbonization process, which is applicable to non-caking and slightly caking coals. It is found that tensile strength and Young`s modulus increase in proportion to a rise in the ultimate carbonization temperature or in the heating rate. Attention is then paid to the maximum carbonization temperature and the heating rate, and a pyrolytic decomposition model is used for the calculation of the reaction rate, amount of hydrogen generated, porosity, amount of tar generated, and the rate of metaplast formation are calculated, and the results are used for the study of the mechanism of the appearance of strength . The amount of liquid tar increases as the amount of gaseous tar or the emission rate of metaplast increases. Graphitization (tightening by baking) advances with a rise in the reaction rate or in the amount of hydrogen generation. As for the macrostructure, coal particles are bonded together by liquid tar, and then the bondage is tightened by baking. 22 refs., 15 figs., 1 tab.

  7. Solid Propellant Flame Spectroscopy

    Science.gov (United States)

    1988-08-01

    400 jm to reach the maximum flame temperature, a distance that can be reduced by replacing the HTPB binder with a polyester or CMDB binder. The...the dark zone for propellants similar to HIX2 is 2-2.5 mm at 1.8 MPa (18 atm, 265 psia) (Ref. 22,187). In contrast, the dark zone for HMX CMDB ...propellants eliminates the dark zone is not surprising, since TMETN is a nitrate ester as was the double-base matrix of Kubota’s HMX CMDB propellant. A

  8. Dynamics and structure of stretched flames

    Energy Technology Data Exchange (ETDEWEB)

    Law, C.K. [Princeton Univ., NJ (United States)

    1993-12-01

    This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

  9. Flame wrinkles from the Zhdanov–Trubnikov equation

    Energy Technology Data Exchange (ETDEWEB)

    Joulin, Guy, E-mail: guy.joulin@lcd.ensma.fr [Institut P-prime, UPR 3346 CNRS, ENSMA, Université de Poitiers, 1 rue Clément Ader, B.P. 40109, 86961 Futuroscope Cedex, Poitiers (France); Denet, Bruno, E-mail: bruno.denet@irphe.univ-mrs.fr [Aix-Marseille Univ., IRPHE, UMR 7342 CNRS, Technopole de Château-Gombert, 49 rue Joliot-Curie, 13384 Marseille Cedex 13 (France)

    2012-04-30

    The Zhdanov–Trubnikov equation describing wrinkled premixed flames is studied, using pole decompositions as starting points. Its one-parameter (−1⩽c⩽+1) nonlinearity generalises the Michelson–Sivashinsky equation (c=0) to a stronger Darrieus–Landau instability. The shapes of steady flame crests (or periodic cells) are deduced from Laguerre (or Jacobi) polynomials when c≈−1, which numerical resolutions confirm. Large wrinkles are analysed via a pole density: adapting results of Dunkl relates their shapes to the generating function of Meixner–Pollaczek polynomials, which numerical results confirm for −10 (over-stabilisation) such analytical solutions can yield accurate flame shapes for 0⩽c⩽0.6. Open problems are invoked. -- Highlights: ► We study a 1-parameter (c) nonlinear integral equation and get flame-wrinkle shapes. ► Pole decompositions of the front slope (periodic or not) are used as a basis. ► In limiting cases we relate the flame shapes to Laguerre or Jacobi polynomials. ► Linear integral equations for pole densities give accurate large-wrinkle shapes if c<0. ► Though locally singular the shapes so obtained for c>0 can be fairly accurate.

  10. COAL GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20141574 Chen Hao(Exploration and Development Research Institute,Daqing Oilfield Company,Daqing 163712,China)High-Resolution Sequences and Coal Accumulating Laws in Nantun Formation of Huhe Lake Sag(Petroleum Geology&Oilfield Development in Daqing,ISSN1000-3754,CN23-1286/TQ,32(4),2013,p.15-19,5 illus.,15 refs.)Key words:coal accumulation regularity,coal

  11. COAL GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091159 Gao Yan(No.3 Prospecting Team of Anhui Bureau of Coal Geology,Suzhou 234000,China) Effect of Depositional Environment of Coal-Bearing Stratum on Major Coal Seams in Suntan Coalmine,Anhui Province(Geology of Anhui,ISSN 1005- 6157,CN34-1111/P,18(2),2008,p.114 -117,5 illus.,1 ref.,with English abstract)

  12. Novel fragmentation model for pulverized coal particles gasification in low temperature air thermal plasma

    OpenAIRE

    Jovanović Rastko D.; Cvetinović Dejan B.; Stefanović Predrag Lj.; Škobalj Predrag D.; Marković Zoran J.

    2016-01-01

    New system for start-up and flame support based on coal gasification by low temperature air thermal plasma is planned to supplement current heavy oil system in Serbian thermal power plants in order to decrease air pollutions emission and operational costs. Locally introduced plasma thermal energy heats up and ignites entrained coal particles, thus starting chain process which releases heat energy from gasified coal particles inside burner channel. Important...

  13. Fluidized bed coal combustion reactor

    Science.gov (United States)

    Moynihan, P. I.; Young, D. L. (Inventor)

    1981-01-01

    A fluidized bed coal reactor includes a combination nozzle-injector ash-removal unit formed by a grid of closely spaced open channels, each containing a worm screw conveyor, which function as continuous ash removal troughs. A pressurized air-coal mixture is introduced below the unit and is injected through the elongated nozzles formed by the spaces between the channels. The ash build-up in the troughs protects the worm screw conveyors as does the cooling action of the injected mixture. The ash layer and the pressure from the injectors support a fluidized flame combustion zone above the grid which heats water in boiler tubes disposed within and/or above the combustion zone and/or within the walls of the reactor.

  14. Research on the Simulation of High-density Electrical Method in Detecting Coal Fire%高密度电法探测煤火的正演模拟研究

    Institute of Scientific and Technical Information of China (English)

    邵振鲁; 王雁鸣; 王德明

    2012-01-01

    通过建立煤火的地电模型,采用有限差分法分别对温纳装置进行正演模拟,得到模型的视电阻率断面数据.在对数据加入5%噪声后反演得到视电阻率拟断面图.反演结果表明:火区燃烧中心、烧空区和松散冒落带在反演视电阻率拟断面图上均反映出了异常且与模型相吻合.验证了高密度电法探测煤火的有效性和准确性.因此,高密度电法以其高精度、大信息量的优势,在煤火探测领域必将取得很好的效果.%Firstly, the geo-electric model of coal fire is established. Then, the Wenner array type is forward simulated to get the apparent resistivity data in cross-section by using the finite difference method. Thirdly, 5% noise is added to the data and get the sectional drawing of apparent resistivity by inversing the data. Inversion results show that; burning center, burned cave and loose zone reflect the abnormalities in the sectional drawing of apparent resistivity, and are consistent with the model. This verifies the effectiveness and accuracy of high-density electrical method in detecting coal fire. Therefore, with the advantages of high-precision and large amount of information , high-density electrical method will achieve good effect in field detecting coal fire.

  15. Smoke suppression properties of ferrite yellow on flame retardant thermoplastic polyurethane based on ammonium polyphosphate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xilei; Jiang, Yufeng; Jiao, Chuanmei, E-mail: jiaochm@qust.edu.cn

    2014-02-15

    Highlights: • Smoke suppression of FeOOH on flame retardant TPU composites has been investigated. • FeOOH has excellent smoke suppression abilities for flame retardant TPU composites. • FeOOH has good ability of char formation, hence improved smoke suppression property. -- Abstract: This article mainly studies smoke suppression properties and synergistic flame retardant effect of ferrite yellow (FeOOH) on flame retardant thermoplastic polyurethane (TPU) composites using ammonium polyphosphate (APP) as a flame retardant agent. Smoke suppression properties and synergistic flame retardant effect of FeOOH on flame retardant TPU composites were intensively investigated by smoke density test (SDT), cone calorimeter test (CCT), scanning electron microscopy (SEM), and thermal-gravimetric analysis (TGA). Remarkably, the SDT results show that FeOOH can effectively decrease the amount of smoke production with or without flame. On the other hand, the CCT data reveal that the addition of FeOOH can apparently reduce heat release rate (HRR), total heat release (THR), and total smoke release (TSR), etc. Here, FeOOH is considered to be an effective smoke suppression agent and a good synergism with APP in flame retardant TPU composites, which can greatly improve the structure of char residue realized by TGA and SEM results.

  16. Bidirectional ionic wind in nonpremixed counterflow flames with DC electric fields

    KAUST Repository

    Park, Daegeun

    2016-05-05

    Under an electric field, ions in the reaction zone of a flame generate a bulk flow motion called ionic wind. Because the majority of ions are positive, ionic wind is commonly considered to be unidirectional toward the cathode. A more thorough understanding of the effects of electric fields on flames could be obtained by clarifying the role of minor negative ions in the ionic wind. Here, we report on the effects of direct current on nonpremixed counterflow flames by visualizing the ionic wind. We found that the original flow field separates near the flame when it locates at a flow stagnation plane, resulting in a double-stagnant flow configuration. This evidences a bidirectional ionic wind blowing from the flame to both the cathode and the anode due to the positive and the negative ions, respectively. Meanwhile, an electric body force pulls the flame toward the cathode. Thus, the electric field affects the strain rate and the axial location of the stoichiometry, which are important for characterizing nonpremixed counterflow flames. In addition, measurement of the electric current density roughly showed a nearly saturated current when these flames restabilized under relatively high voltage. Detailed explanations of flame behavior, electric currents, and flow characteristics of various fuels are discussed in this study.

  17. Subwoofer and nanotube butterfly acoustic flame extinction

    Science.gov (United States)

    Aliev, Ali E.; Mayo, Nathanael K.; Baughman, Ray H.; Mills, Brent T.; Habtour, Ed

    2017-07-01

    Nonchemical flame control using acoustic waves from a subwoofer and a lightweight carbon nanotube thermoacoustic projector was demonstrated. The intent was to manipulate flame intensity, direction and propagation. The mechanisms of flame suppression using low frequency acoustic waves were discussed. Laminar flame control and extinction were achieved using a thermoacoustic ‘butterfly’ projector based on freestanding carbon nanotube sheets.

  18. Fractal flame structure due to the hydrodynamic Darrieus-Landau instability

    Science.gov (United States)

    Yu, Rixin; Bai, Xue-Song; Bychkov, Vitaly

    2015-12-01

    By using large scale numerical simulations, we obtain fractal structure, which develops at originally planar flame fronts due to the hydrodynamic Darrieus-Landau (DL) instability bending the fronts. We clarify some important issues regarding the DL fractal flames, which have been debated for a long time. We demonstrate an increase of the flame propagation speed with the hypothetic channel width, which controls the length scale of the instability development. We show that this increase may be fitted by a power law indicating the mean fractal properties of the flame front structure. The power exponent in this law is found to be not a universal constant, rather it depends on the flame properties—on the density drop at the front. Using box counting on the simulated flame front shapes we show the fractal flame dimension at the intermediate scale is smaller than the one given by the power law, but it has a similar dependency on the density drop. We also obtain a formation of pockets at the DL fractal flame fronts, which previously has been associated only with turbulent burning.

  19. Turbulence in laminar premixed V-flames

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Xiaoqian(张孝谦); LEI; Yu(雷宇); WANG; Baorui(王宝瑞); WANG; Yue(王岳); WEI; Minggang(韦明罡)

    2003-01-01

    Strong velocity fluctuations had been found in the laminar premixed V-flames. These velocity fluctuations are closely related to the chemical reaction. But the effects of the upstream combustible mixture velocity on the velocity fluctuations inside the flame are quite weak. The probability distribution function (PDF) of the velocity in the centre region of the flame appears "flat top" shaped. By analyzing the experiment results the flame-flow interactions are found to affect the flame not only at large scale in the flow field but also at small scale inside the flame. These effects will give rise to flame generated small scale turbulences.

  20. IR sensor for monitoring of burner flame; IR sensor foer oevervakning av braennarflamma

    Energy Technology Data Exchange (ETDEWEB)

    Svanberg, Marcus; Funkquist, Jonas; Clausen, Soennik; Wetterstroem, Jonas

    2007-12-15

    To obtain a smooth operation of the coal-fired power plants many power plant managers have installed online mass flow measurement of coal to all burners. This signal is used to monitor the coal mass flow to the individual burner and match it with appropriate amount of air and also to monitor the distribution of coal between the burners. The online mass flow measurement system is very expensive (approximately 150 kEUR for ten burners) and is not beneficial for smaller plants. The accuracy of the measurement and the sample frequency are also questionable. The idea in this project has been to evaluate a cheaper system that can present the same information and may also provide better accuracy and faster sample frequency. The infrared sensor is a cheap narrow banded light emission sensor that can be placed in a water cooed probe. The sensor was directed at the burner flame and the emitted light was monitored. Through calibration the mass flow of coal can be presented. Two measurement campaigns were performed. Both campaigns were carried out in Nordjyllandsverket in Denmark even though the second campaign was planned to be in Uppsala. Due to severe problems in the Uppsala plant the campaign was moved to Nordjyllandsverket. The pre-requisites for the test plant were that online measurement of coal flow was installed. In Nordjyllandsverket 4 out of 16 burners have the mass flow measurement installed. Risoe Laboratories has vast experiences in the IR technology and they provided the IR sensing equipment. One IR sensor was placed in the flame guard position just behind the flame directed towards the ignition zone. A second sensor was placed at the boiler wall directed towards the flame. The boiler wall position did not give any results and the location was not used during the second campaign. The flame-guard-positioned-sensor- signal was thoroughly evaluated and the results show that there is a clear correlation between the coal mass flow and the IR sensor signal. Tests were

  1. Premixed flame propagation in vertical tubes

    CERN Document Server

    Kazakov, Kirill A

    2015-01-01

    Analytical treatment of premixed flame propagation in vertical tubes with smooth walls is given. Using the on-shell flame description, equations describing quasi-steady flame with a small but finite front thickness are obtained and solved numerically. It is found that near the limits of inflammability, solutions describing upward flame propagation come in pairs having close propagation speeds, and that the effect of gravity is to reverse the burnt gas velocity profile generated by the flame. On the basis of these results, a theory of partial flame propagation driven by the gravitational field is developed. A complete explanation is given of the intricate observed behavior of limit flames, including dependence of the inflammability range on the size of the combustion domain, the large distances of partial flame propagation, and the progression of flame extinction. The role of the finite front-thickness effects is discussed in detail. Also, various mechanisms governing flame acceleration in smooth tubes are ide...

  2. COAL GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131668 Chang Huizhen(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,CUMT,Ministry of Edu-cation,School of Resource and Earth Science,China University of Mining and Technology,Xuzhou 221008,China);Qin Yong Differences in of Pore Structure of Coals and Their Impact on the Permeability of Coals from the

  3. Electrical Aspects of Impinging Flames

    Science.gov (United States)

    Chien, Yu-Chien

    This dissertation examines the use of electric fields as one mechanism for controlling combustion as flames are partially extinguished when impinging on nearby surfaces. Electrical aspects of flames, specifically, the production of chemi-ions in hydrocarbon flames and the use of convective flows driven by these ions, have been investigated in a wide range of applications in prior work but despite this fairly comprehensive effort to study electrical aspects of combustion, relatively little research has focused on electrical phenomena near flame extinguishment, nor for flames near impingement surfaces. Electrical impinging flames have complex properties under global influences of ion-driven winds and flow field disturbances from the impingement surface. Challenges of measurements when an electric field is applied in the system have limited an understanding of changes to the flame behavior and species concentrations caused by the field. This research initially characterizes the ability of high voltage power supplies to respond on sufficiently short time scales to permit real time electrical flame actuation. The study then characterizes the influence of an electric field on the impinging flame shape, ion current and flow field of the thermal plume associated with the flame. The more significant further examinations can be separated into two parts: 1) the potential for using electric fields to control the release of carbon monoxide (CO) from surface-impinging flames, and 2) an investigation of controlling electrically the heat transfer to a plate on which the flame impinges. Carbon monoxide (CO) results from the incomplete oxidation of hydrocarbon fuels and, while CO can be desirable in some syngas processes, it is usually a dangerous emission from forest fires, gas heaters, gas stoves, or furnaces where insufficient oxygen in the core reaction does not fully oxidize the fuel to carbon dioxide and water. Determining how carbon monoxide is released and how heat transfer

  4. Numerical Simulation of Oxy-coal Combustion for a Swirl Burner with EDC Model

    Institute of Scientific and Technical Information of China (English)

    崔凯; 刘冰; 吴玉新; 杨海瑞; 吕俊复; 张海

    2014-01-01

    The characteristics of oxy-coal combustion for a swirl burner with a specially designed preheating chamber are studied numerically. In order to increase the accuracy in the prediction of flame temperature and igni-tion position, eddy dissipation concept (EDC) model with a skeletal chemical reaction mechanism was adopted to describe the combustion of volatile matter. Simulation was conducted under six oxidant stream conditions with dif-ferent O2/N2/CO2 molar ratios:21/79/0, 30/70/0, 50/50/0, 21/0/79, 30/0/70 and 50/0/50. Results showed that O2 en-richment in the primary oxidant stream is in favor of combustion stabilization, acceleration of ignition and increase of maximum flame temperature, while the full substitution of N2 by CO2 in the oxidant stream delays ignition and decreases the maximum flame temperature. However, the overall flow field and flame shapes in these cases are very similar at the same flow rate of the primary oxidant stream. Combustion characteristics of the air-coal is similar to that of the oxy-coal with 30%O2 and 70%CO2 in the oxidant stream, indicating that the rear condition is suitable for retrofitting an air-coal fired boiler to an oxy-coal one. The swirl burner with a specially designed preheating chamber can increase flame temperature, accelerate ignition and enhance burning intensity of pulverized coal under oxy-coal combustion. Also, qualitative experimental validation indicated the burner can reduce the overall NOx emission under certain O2 enrichment and oxy-coal combustion conditions against the air-coal combustion.

  5. An evolution equation modeling inversion of tulip flames

    Energy Technology Data Exchange (ETDEWEB)

    Dold, J.W. [Univ. of Bristol (United Kingdom). School of Mathematics; Joulin, G. [E.N.S.M.A., Poitiers (France). Lab. d`Energetique et de Detonique

    1995-02-01

    The authors attempt to reduce the number of physical ingredients needed to model the phenomenon of tulip-flame inversion to a bare minimum. This is achieved by synthesizing the nonlinear, first-order Michelson-Sivashinsky (MS) equation with the second order linear dispersion relation of Landau and Darrieus, which adds only one extra term to the MS equation without changing any of its stationary behavior and without changing its dynamics in the limit of small density change when the MS equation is asymptotically valid. However, as demonstrated by spectral numerical solutions, the resulting second-order nonlinear evolution equation is found to describe the inversion of tulip flames in good qualitative agreement with classical experiments on the phenomenon. This shows that the combined influences of front curvature, geometric nonlinearity and hydrodynamic instability (including its second-order, or inertial effects, which are an essential result of vorticity production at the flame front) are sufficient to reproduce the inversion process.

  6. Testing of Action of Direct Flame on Concrete

    Science.gov (United States)

    Valek, Jaroslav; Novosad, Petr

    2015-01-01

    The paper states results of experimental exposition of concrete test specimens to direct flame. Concrete test specimens made from various mixtures differing in the type of aggregate, binder, dispersed reinforcement, and technological procedure were subjected to thermal load. Physicomechanical and other properties of all test specimens were tested before exposition to open flame: density, compressive strength, flexural strength, moisture content, and surface appearance. The specimens were visually observed during exposition to open flame and changes were recorded. Exposed surface was photographically documented before thermal load and at 10-minute intervals. Development of temperature of the specimens was documented with a thermocamera. After exposition to thermal load and cooling down, concrete specimens were visually observed, network of cracks was photographically documented, and maximal depth of spalled area was measured. PMID:25830162

  7. Effect of Water Invasion on Outburst Predictive Index of Low Rank Coals in Dalong Mine.

    Science.gov (United States)

    Jiang, Jingyu; Cheng, Yuanping; Mou, Junhui; Jin, Kan; Cui, Jie

    2015-01-01

    To improve the coal permeability and outburst prevention, coal seam water injection and a series of outburst prevention measures were tested in outburst coal mines. These methods have become important technologies used for coal and gas outburst prevention and control by increasing the external moisture of coal or decreasing the stress of coal seam and changing the coal pore structure and gas desorption speed. In addition, techniques have had a significant impact on the gas extraction and outburst prevention indicators of coal seams. Globally, low rank coals reservoirs account for nearly half of hidden coal reserves and the most obvious feature of low rank coal is the high natural moisture content. Moisture will restrain the gas desorption and will affect the gas extraction and accuracy of the outburst prediction of coals. To study the influence of injected water on methane desorption dynamic characteristics and the outburst predictive index of coal, coal samples were collected from the Dalong Mine. The methane adsorption/desorption test was conducted on coal samples under conditions of different injected water contents. Selective analysis assessed the variations of the gas desorption quantities and the outburst prediction index (coal cutting desorption index). Adsorption tests indicated that the Langmuir volume of the Dalong coal sample is ~40.26 m3/t, indicating a strong gas adsorption ability. With the increase of injected water content, the gas desorption amount of the coal samples decreased under the same pressure and temperature. Higher moisture content lowered the accumulation desorption quantity after 120 minutes. The gas desorption volumes and moisture content conformed to a logarithmic relationship. After moisture correction, we obtained the long-flame coal outburst prediction (cutting desorption) index critical value. This value can provide a theoretical basis for outburst prediction and prevention of low rank coal mines and similar occurrence conditions

  8. Effect of Water Invasion on Outburst Predictive Index of Low Rank Coals in Dalong Mine.

    Directory of Open Access Journals (Sweden)

    Jingyu Jiang

    Full Text Available To improve the coal permeability and outburst prevention, coal seam water injection and a series of outburst prevention measures were tested in outburst coal mines. These methods have become important technologies used for coal and gas outburst prevention and control by increasing the external moisture of coal or decreasing the stress of coal seam and changing the coal pore structure and gas desorption speed. In addition, techniques have had a significant impact on the gas extraction and outburst prevention indicators of coal seams. Globally, low rank coals reservoirs account for nearly half of hidden coal reserves and the most obvious feature of low rank coal is the high natural moisture content. Moisture will restrain the gas desorption and will affect the gas extraction and accuracy of the outburst prediction of coals. To study the influence of injected water on methane desorption dynamic characteristics and the outburst predictive index of coal, coal samples were collected from the Dalong Mine. The methane adsorption/desorption test was conducted on coal samples under conditions of different injected water contents. Selective analysis assessed the variations of the gas desorption quantities and the outburst prediction index (coal cutting desorption index. Adsorption tests indicated that the Langmuir volume of the Dalong coal sample is ~40.26 m3/t, indicating a strong gas adsorption ability. With the increase of injected water content, the gas desorption amount of the coal samples decreased under the same pressure and temperature. Higher moisture content lowered the accumulation desorption quantity after 120 minutes. The gas desorption volumes and moisture content conformed to a logarithmic relationship. After moisture correction, we obtained the long-flame coal outburst prediction (cutting desorption index critical value. This value can provide a theoretical basis for outburst prediction and prevention of low rank coal mines and similar

  9. COAL GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111053 Chen Jian(School of Earth and Environment,Anhui University of Science and Technology,Huainan 232001,China);Liu Wenzhong Organic Affinity of Trace Elements in Coal from No.10 Coal-Bed at Western Huagou,Guoyang(Coal Geology & Exploration,ISSN1001-1986,CN61-1155/P,38(4),2010,p.16-20,24,3 illus.,3 tables,19 refs.)Key words:coal,minor elements,Anhui Province In order to study the organic affinity of trace elements in coal from No.10 coal-bed at western Huagou,Guoyang,10 borehole samples were collected at exploration area of Huaibei mining area.The contents of 12 kinds of trace elements were determined by the inductively coupled plasma mass spectrometry(ICP-MS),the total organic carbon(TOC)of coal was determined by LECO carbon and sulfur analyzer,and the organic affinity of trace elements were deduced from the correlations between contents and TOCs.The results showed that the contents of V,Cr,Co,Ni,Mo,Cd,Sb,Pb and Zn were lower than

  10. Role of flame generated flow in the formation of tulip flame

    Energy Technology Data Exchange (ETDEWEB)

    Jeung, I.S.; Cho, K.K.; Jeong, K.S.

    1989-01-01

    The role of flame generated flow during the laminar 'tulip' flame formation in a long rectangular combustion vessel was examined by laser Doppler velocimeter measurement, high speed schlieren photographic flame visualization, and combustion vessel pressure measurement. Results of these investigations showed the transition of convex-shaped flame to concave-shaped tulip flame and interactions between the flame shape and flame generated flow in a confined geometry, and gave physical understanding of flow field formation of tulip flame. 15 references.

  11. Evaluation of gas emissions from coal stockpile

    Energy Technology Data Exchange (ETDEWEB)

    Kozinc, J.; Zupancic-Kralj, L.; Zapusek, A. [University of Ljubljana, Ljubljana (Slovenia). Faculty of Chemistry & Chemical Technology

    2004-05-01

    Gas emissions of carbon dioxide, methane, dimethylsulfide, carbon monoxide and oxygen from a coal stockpile in Velenje were determined. Gases from the coal stockpile were collected in Alltech Standard sampling bags and then analysed using a capillary gas chromatograph and electrochemical sensors. A flame ionisation detector equipped with a Zr/Ni catalytic reactor was used for the determination of methane and carbon dioxide. Dimethylsulfide was detected with a flame photometric detector, and the concentrations of carbon monoxide and oxygen were determined by use of electrochemical sensors. The results showed that the main influence on gas emissions is related to the ambient temperature. Emissions of carbon dioxide during summer 2001 (average temperature during sampling period was 24{sup o}C) were approximately 30-times higher than during winter 2002 (average temperature during sampling period was -2{sup o}C) and were also influenced by the oxygen concentration. Carbon dioxide is mainly formed by oxidation of coal. Methane and dimethylsulfide are desorbed from coal, and are present in higher concentrations in stockpile emissions when stockpiles are renewed. The dimethylsulfide concentration, in contrast to laboratory experiments in stockpile emissions, falls immediately due to photo-degradation.

  12. Influence of Coal Particle Size on Coal Adsorption and Desorption Characteristics

    Science.gov (United States)

    Zhang, Lei; Aziz, Naj; Ren, Ting; Nemcik, Jan; Tu, Shihao

    2014-10-01

    Accurate testing coal isotherm can play a significant role in the areas of coal seam gas drainage, outburst control, CO2 geo-sequestration, coalbed methane (CBM) and enhanced coalbed methane recovery (ECBM) etc. The effect of particle size on the CO2 and CH4 sorption capacity of bituminous coal from Illawarra, Australia was investigated at 35°C and at pressure up to 4 MPa. A unique indirect gravimetric apparatus was used to measure the gas adsorption and desorption isotherms of coal of different particle sizes ranging from around 150 urn to 16 mm. Langmuir model was used to analysis the experimental results of all gases. Coal particle size was found to have an apparent effect on the coal ash content and helium density results. Coal with larger particle size had higher ash content and higher helium density. The sorption isotherm was found to be highly sensitive with helium density of coal which was determined in the procedure of testing the void volume of sample cell. Hence, coal particle size had a significant influence on the coal sorption characteristics including sorption capacity and desorption hysteresis for CO2 and CH4, especially calculated with dry basis of coal. In this study, the 150-212 um (150 um) coal samples achieved higher sorption capacity and followed by 2.36-3.35 mm (2.4 mm), 8-9.5 mm (8 mm) and 16-19 mm (16 mm) particle size samples. However, the differences between different coal particles were getting smaller when the sorption isotherms are calculated with dry ash free basis. Test with 150 um coal samples were also found to have relatively smaller desorption hysteresis compared with the other larger particle size samples. The different results including adsorption/desorption isotherm, Langmuir parameters and coal hysteresis were all analysed with the CO2 and CH4 gases.

  13. Environmentally and economically efficient utilization of coal processing waste.

    Science.gov (United States)

    Dmitrienko, Margarita A; Strizhak, Pavel A

    2017-11-15

    High concentrations of hazardous anthropogenic emissions (sulfur, nitrogen and carbon oxides) from solid fuel combustion in coal burning plants cause environmental problems that have been especially pressing over the last 20-30 years. A promising solution to these problems is a switch from conventional pulverized coal combustion to coal-water slurry fuel. In this paper, we pay special attention to the environmental indicators characterizing the combustion of different coal ranks (gas, flame, coking, low-caking, and nonbaking coals) and coal-water slurry fuels based on the coal processing waste - filter cakes. There have been no consistent data so far on the acceptable intervals for the anthropogenic emissions of sulfur (SOx), nitrogen (NOx) and carbon (CO, CO2) oxides. Using a specialized combustion chamber and gas analyzing system, we have measured the concentrations of typical coal and filter-cake-based CWS combustion products. We have also calculated the typical combustion heat of the fuels under study and measured the ratio between environmental and energy attributes. The research findings show that the use of filter cakes in the form of CWS is even better than coals in terms of environment and economy. Wide utilization of filter cakes solves many environmental problems: the areas of contaminated sites shrink, anthropogenic emissions decrease, and there is no need to develop new coal mines anymore. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Plasma-supported coal combustion in boiler furnace

    Energy Technology Data Exchange (ETDEWEB)

    Askarova, A.S.; Karpenko, E.I.; Lavrishcheva, Y.I.; Messerle, V.E.; Ustimenko, A.B. [Kazakh National University, Alma Ata (Kazakhstan). Dept. of Physics

    2007-12-15

    Plasma activation promotes more effective and environmentally friendly low-rank coal combustion. This paper presents Plasma Fuel Systems that increase the burning efficiency of coal. The systems were tested for fuel oil-free start-up of coal-fired boilers and stabilization of a pulverized-coal flame in power-generating boilers equipped with different types of burners, and burning all types of power-generating coal. Also, numerical modeling results of a plasma thermochemical preparation of pulverized coal for ignition and combustion in the furnace of a utility boiler are discussed in this paper. Two kinetic mathematical models were used in the investigation of the processes of air/fuel mixture plasma activation: ignition and combustion. A I-D kinetic code PLASMA-COAL calculates the concentrations of species, temperatures, and velocities of the treated coal/air mixture in a burner incorporating a plasma source. The I-D simulation results are initial data for the 3-D-modeling of power boiler furnaces by the code FLOREAN. A comprehensive image of plasma-activated coal combustion processes in a furnace of a pulverized-coal-fired boiler was obtained. The advantages of the plasma technology are clearly demonstrated.

  15. Experimental investigation of syngas flame stability using a multi-tube fuel injector in a high pressure combustor

    Science.gov (United States)

    Maldonado, Sergio Elzar

    Over 92% of the coal consumed by power plants is used to generate electricity in the United States (U.S.). The U.S. has the world's largest recoverable reserves of coal, it is estimated that reserves of coal will last more than 200 years based in current production and demand levels. Integrated Gasification Combined Cycle (IGCC) power plants aim to reduce the amount of pollutants by gasifying coal and producing synthesis gas. Synthesis gas, also known as syngas, is a product of coal gasification and can be used in gas turbines for energy production. Syngas is primarily a mixture of hydrogen and carbon monoxide and is produced by gasifying a solid fuel feedstock such as coal or biomass. The objective of the thesis is to create a flame stability map by performing various experiments using high-content hydrogen fuels with varying compositions of hydrogen representing different coal feedstocks. The experiments shown in this thesis were performed using the High-Pressure Combustion facility in the Center for Space Exploration Technology Research (CSETR) at the University of Texas at El Paso (UTEP). The combustor was fitted with a novel Multi-Tube fuel Injector (MTI) designed to improve flame stability. This thesis presents the results of testing of syngas fuels with compositions of 20, 30, and 40% hydrogen concentrations in mixtures with carbon monoxide. Tests were completed for lean conditions ranging from equivalence ratios between 0.6 and 0.9. The experimental results showed that at an equivalence ratio of 0.6, a stable flame was not achieved for any of the fuel mixtures tested. It was also observed that the stability region of the syngas flame increased as equivalence ratio and the hydrogen concentration in syngas fuel increases with the 40% hydrogen-carbon monoxide mixture demonstrating the greatest stability region. Design improvements to the MTI are also discussed as part of the future work on this topic.

  16. Formation and retention of methane in coal. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hucka, V.J.; Bodily, D.M.; Huang, H.

    1992-05-15

    The formation and retention of methane in coalbeds was studied for ten Utah coal samples, one Colorado coal sample and eight coal samples from the Argonne Premium Coal Sample Bank.Methane gas content of the Utah and Colorado coals varied from zero to 9 cm{sup 3}/g. The Utah coals were all high volatile bituminous coals. The Colorado coal was a gassy medium volatile bituminous coal. The Argonne coals cover a range or rank from lignite to low volatile bituminous coal and were used to determine the effect of rank in laboratory studies. The methane content of six selected Utah coal seams and the Colorado coal seam was measured in situ using a special sample collection device and a bubble desorbometer. Coal samples were collected at each measurement site for laboratory analysis. The cleat and joint system was evaluated for the coal and surrounding rocks and geological conditions were noted. Permeability measurements were performed on selected samples and all samples were analyzed for proximate and ultimate analysis, petrographic analysis, {sup 13}C NMR dipolar-dephasing spectroscopy, and density analysis. The observed methane adsorption behavior was correlated with the chemical structure and physical properties of the coals.

  17. Measurement and simulation of swirling coal combustion

    Institute of Scientific and Technical Information of China (English)

    Liyuan Hu; Lixing Zhou; Yonghao Luo; Caisong Xu

    2013-01-01

    Particle image velocimetry (PIV),thermocouples and flue gas analyzer are used to study swirling coal combustion and NO formation under different secondary-air ratios.Eulerian-Lagrangian large-eddy simulation (LES) using the Smagorinsky-Lilly sub-grid scale stress model,presumed-PDF fast chemistry and eddy-break-up (EBU) gas combustion models,particle devolatilization and particle combustion models,are simultaneously used to simulate swirling coal combustion.Statistical LES results are validated by measurement results.Instantaneous LES results show that the coherent structures for swirling coal combustion are stronger than those for swirling gas combustion.Particles are shown to concentrate along the periphery of the coherent structures.Combustion flame is located in the high vorticity and high particle concentration zones.Measurement shows that secondary-air ratios have little effect on final NO formation at the exit of the combustor.

  18. Combustion and NOx Emission Behavior of Chinese Coals

    Institute of Scientific and Technical Information of China (English)

    CHENHonggang; XIEKechang

    2002-01-01

    Seven Chinese coals ranking from anthracite to sub-bituminous from the Shanxi province were selected for study to forecast the combustion and NOx emission behavior.Three UK,one Indonesia and one South Africa coal was included in the study for reference.A flat flame-turbulent jet apparatus was employed to assess flame stability,ignition performance and NOx emission behavior for the initial stage of devolatilization and combustion. This apparatus can simulate particle heating rates,maximum temperatures and the influence of the turbulent fluid interactionson the fate of volatiles.To simulate processes occurring over longer residence time, additional devolatilization experiments were performed in a drop tube furnace.Char reactivity was studied through thermogravimetric analysis.Finally,fouling propensity was studied with the aid of a purpose-built laboratory combustor that enabled the characteristics of the ash deposit to be assessed empirically.The results show that Chinese coals do not appear to possess unusual features in respect of NOx formation,flame stability and ignition,char burnout and ash slagging.The range of coals available in China appears sufficiently broad that suits all requirements.In particular,Shenfu coal,with its initial fast devolatilization and nitrogen release rates and its low initial nitrogen content and high char reactivity,will perform well when fired in industrial boilers as far as NOx emission,flame stability and combustion efficiency are concerned.Pingshuo coal exhibits high char reactivity and an attractive slagging performance suggesting that this fuel represents a good compromise between NOx emission and overall plant efficiency.

  19. CFD prediction of physical field for multi-air channel pulverized coal burner in rotary kiln

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A 3-D numerical simulation with CFX software on physical field of multi-air channel coal burner in rotary kiln was carried out. The effects of various operational and structural parameters on flame feature and temperature distribution were investigated. A thermal measurement was conducted on a rotary kiln (4.5 m in diameter, 90 m in length) with four-air channel coal burner to determine the boundary conditions and to verify the simulation results.The calculation result shows that the distribution of velocity near burner exit is saddle-like; recirculation zones near nozzle and wall are useful for mixture primary air with coal and high temperature fume. A little central airflow can avoid coal backing up and cool nozzle. Adjusting the ratio of internal airflow to outer airflow is an effective and major means to regulate flame and temperature distribution in sintering region. Large whirlcone angle can intensify disturbution range at flame root to accelerate ignition and mixture. Large coal size can reduce high temperature region and result in coal combusting insufficiently. Too much combustion air will lengthen flame and increase heat loss.

  20. Reforming Practice of Monitoring and Control System of Heavy-media Density in Chengzhuang Coal Preparation Plant%成庄矿选煤厂重介质密度监控系统的改造实践

    Institute of Scientific and Technical Information of China (English)

    张士聪; 王波; 王然风

    2011-01-01

    In view of the problem that existing monitoring and control system of heavy-media coal separation cannot reflect real-time information to field operating personnel real-timely in Chengzhuang Coal Preparation Plant, the paper proposed a reforming scheme with S7-300 PLC, SIMATIC WinCC and VB6.0 for current minotoring and control system.It introduced communication process of WinCC with VB6.0 and S7-300 PLC.The reformed system achieves a dynamic display of data and monitoring of main parameters through putting a piece of LED display screen in heavy-media coal separation workship, which makes operators on duty finish density control according to real-time data on LED display screen, and all coal separation workshops share information by OPC interface of WinCC, so as to realize centralized control and manage.Besides, cost of the system reform is low by using simple external program to collect and display data.%针对成庄矿选煤厂现有重介选煤监控系统存在不能将实时信息及时向现场操作人员反映的问题,提出一种采用S7-300 PLC、SIMATIC WinCC及VB6.0软硬件平台对现有监控系统进行改造的方案,介绍了WinCC与VB6.0及S7-300 PLC的通信过程.改造后的系统将LED显示屏放置在重介选煤车间,实现了数据的动态显示和主要参数的监控,值班人员可以在显示屏实时数据的指导下完成密度调控;通过WinCC提供的OPC接口,各选煤车间可以实现信息共享,从而方便了全厂的集中控制、管理;系统通过调用简单的外部程序就可采集和显示数据,改造成本低廉.

  1. British coal

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, M.

    2009-03-15

    The paper describes a visit to UK's Daw Mill in north Warwickshire to find out about a planned expansion of the coal mine. Daw Mill, 10 km west of Coventry is the UK's largest underground coal mine. The coal is extracted by an Eckhoff Sl500 coal shearer that traverses the coalface. Overarching the shearer is a series of electro-hydraulically operated powered roof supports (PRS) over the roof and coalface that are advanced forward after each pass of the shearer. The void behind the PRS is then allowed to collapse. The coalface is currently 295 m long, but there are plans to extend the replacement coalface to 357 m. Under the shearer is an armored face conveyor (AFC) that receives and transports the coal along the coalface and deposits it onto the beam stage loader, which sits at 90{sup o} to the AFC. The coal is turned by a deflector plough on the AFC headframe and is transferred to the belt conveyor to begin its journey out of the mine. Last year two significant records were broken at Daw Mill - the fastest million tonnes achieved and the European record for a single face of 3.2 Mt. The 300s area of the mine has already been mapped out and development teams are constructing roadways to facilitate more mining. To maintain annual production in excess of three million tonnes will require at least 5,000 m of roadways to access the coal, and install equipment. These investments are supported by proven reserves. Seismic surveys and borehole drilling has shown approximately 20 Mt of extractable coal in the 300s area which extends over 15 km{sup 2}. These panels will be the next to be mined in a sequence that extends to 2014. 2 photos.

  2. Mechanistic aspects of ionic reactions in flames

    DEFF Research Database (Denmark)

    Egsgaard, H.; Carlsen, L.

    1993-01-01

    Some fundamentals of the ion chemistry of flames are summarized. Mechanistic aspects of ionic reactions in flames have been studied using a VG PlasmaQuad, the ICP-system being substituted by a simple quartz burner. Simple hydrocarbon flames as well as sulfur-containing flames have been investigated....... The simple hydrocarbon flames are dominated by a series of hydrocarbonic ions and, to a minor extent, protonated oxo-compounds. The introduction of sulfur to the flames leads to significant changes in the ion composition, as sulfur-containing species become dominant. The ability of the technique to study...

  3. Coal mining: coal in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Arguelles Martinez, A.; Lugue Cabal, V.

    1984-01-01

    The Survey of Spanish Coal Resources published by the Centre for Energy Studies in 1979 is without doubt the most serious and full study on this subject. The coal boom of the last few years and the important role it will play in the future, as well as the wealth of new information which has come to light in the research carried out in Spanish coalfields by both the public and private sector, prompted the General Mine Management of the Ministry of Industry and Energy to commission IGME to review and update the previous Survey of Spanish Coal Resources of November 1981.

  4. Blended coals for improved coal water slurries

    Institute of Scientific and Technical Information of China (English)

    GU Tian-ye; WU Guo-guang; LI Qi-hui; SUN Zhi-qiang; ZENG Fang; WANG Guang-you; MENG Xian-liang

    2008-01-01

    Three coal samples of different ranks were used to study the effect of coal blending on the preparation of Coal Water Slurry (CWS). The results show that by taking advantage of two kinds of coal, the coal concentration in slurry made from hard-to-pulp coal can be effectively improved and increased by 3%-5% generally. DLT coal (DaLiuTa coal mine) is very poor in slurryability and the stability and rheology of the resulting slurry are not very good. When the amount of easily slurried coal is more than 30%, all properties of the CWS improve and the CWS meets the requirements for use as fuel. Coalification, porosity, surface oxygenic functional groups, zeta potential and grindability have a great effect on the performance of blended coal CWS. This leads to some differences in performance between the slurry made from a single coal and slurry made from blended coal.

  5. Research on flame retardation of wool fibers

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, Ichiro; Ametani, Kazuo; Sawai, Takeshi (Tokyo Metropolitan Isotope Research Center (Japan))

    1990-01-01

    Flame retardant, vinyl phosphonate oligomer, was uniformly impregnated in wool fibers, and by irradiating low energy electron beam or cobalt-60 gamma ray, the flame retardation of fabrics was attempted, as the results, the following knowledges were obtained. At the rate of sticking of flame retardant lower than that in cotton fabrics, sufficient flame retarding property can be given. The flame retarding property withstands 30 times of washing. The lowering of strength due to the processing hardly arose. For the flame retardation, gamma-ray was more effective than electron beam. Since the accidents of burning clothes have occurred frequently, their flame retardation has been demanded. So far the flame retardation of cotton fabrics has been advanced, but this time the research on the flame retardation of wool fabrics was carried out by the same method. The experimental method is explained. As for the performance of the processed fabrics, the rate of sticking of the flame retardant, the efficiency of utilization, the flame retarding property, the endurance in washing and the tensile and tearing strength were examined. As the oxygen index was higher, the flame retarding property was higher, and in the case of the index being more than 27, the flame retarding property is sufficient, that is, the rate of sticking of 6% in serge and 5% in muslin. (K.I.).

  6. Investigating by EPR the reaction processes of intermediate products from the thermodestruction of binary mixtures of coals

    Energy Technology Data Exchange (ETDEWEB)

    Ikonomopulo, V.P.

    1983-03-01

    Binary mixtures of long-flame, gas-bituminous, coking, lean-caking, and lean coals are used to study the processes for the interaction of intermediate products of the thermodestruction of coals. The value and sign of the paramagnetic effect which occurs during simultaneous heating of coals in a binary mixture are determined by the relative position of each coal on the metamorphic scale. The possible role of plastification and reaction of the two coals in the formation of an ordered paramagnetic structure are demonstrated. 4 references.

  7. Studying the specific features pertinent to combustion of chars obtained from coals having different degrees of metamorphism and biomass chars

    Science.gov (United States)

    Bestsennyi, I. V.; Shchudlo, T. S.; Dunaevskaya, N. I.; Topal, A. I.

    2013-12-01

    Better conditions for igniting low-reaction coal (anthracite) can be obtained, higher fuel burnout ratio can be achieved, and the problem of shortage of a certain grade of coal can be solved by firing coal mixtures and by combusting coal jointly with solid biomass in coal-fired boilers. Results from studying the synergetic effect that had been revealed previously during the combustion of coal mixtures in flames are presented. A similar effect was also obtained during joint combustion of coal and wood in a flame. The kinetics pertinent to combustion of char mixtures obtained from coals characterized by different degrees of metamorphism and the kinetics pertinent to combustion of wood chars were studied on the RSK-1D laboratory setup. It was found from the experiments that the combustion rate of char mixtures obtained from coals having close degrees of metamorphism is equal to the value determined as a weighted mean rate with respect to the content of carbon. The combustion rate of char mixtures obtained from coals having essentially different degrees of metamorphism is close to the combustion rate of more reactive coal initially in the process and to the combustion rate of less reactive coal at the end of the process. A dependence of the specific burnout rate of carbon contained in the char of two wood fractions on reciprocal temperature in the range 663—833 K is obtained. The combustion mode of an experimental sample is determined together with the reaction rate constant and activation energy.

  8. Soft-chemical synthesis and catalytic activity of Ni-Al and Co-Al layered double hydroxides (LDHs intercalated with anions with different charge density

    Directory of Open Access Journals (Sweden)

    Takahiro Takei

    2014-09-01

    Full Text Available Co-Al and Ni-Al layered double hydroxides (LDHs intercalated with three types of anionic molecules, dodecylsulfate (C12H25SO4−, DS, di-2-ethylsulfosuccinate ([COOC2H3EtBu]2C2H3SO3−, D2ES, and polytungstate (H2W12O4210−, HWO were prepared by means of ion-exchange and co-precipitation processes. With the use of DS and D2ES as intercalation agents, high crystallinity was maintained after intercalation into the LDHs. In the case of HWO, the intercalated LDHs could be obtained by ion-exchange as well as co-precipitation with a decline in the crystallinity; however, unreacted LDH was detected in the ion-exchange samples, and some unwanted phases such as hydroxide and pyrochlore were generated by the co-precipitation process. The maximum specific surface area and pore volume of the Ni-Al sample with intercalated HWO, prepared by the ion-exchange process were 74 m2/g and 0.174 mL/g, respectively. The occupancies of DS, D2ES, and HWO within the interlayer space were approximately 0.3–0.4, 0.5–0.6, and 0.1–0.2, respectively, in the Co-Al and Ni-Al LDHs. Analysis of the catalytic activity demonstrated that the DS-intercalated Ni-Al LDH sample exhibited relatively good catalytic activity for conversion of cyclohexanol to cyclohexanone.

  9. Role of the outer-edge flame on flame extinction in nitrogen-diluted non-premixed counterflow flames with finite burner diameters

    KAUST Repository

    Chung, Yong Ho

    2013-03-01

    This study of nitrogen-diluted non-premixed counterflow flames with finite burner diameters investigates the important role of the outer-edge flame on flame extinction through experimental and numerical analyses. It explores flame stability diagrams mapping the flame extinction response of nitrogen-diluted non-premixed counterflow flames to varying global strain rates in terms of burner diameter, burner gap, and velocity ratio. A critical nitrogen mole fraction exists beyond which the flame cannot be sustained; the critical nitrogen mole fraction versus global strain rate curves have C-shapes for various burner diameters, burner gaps, and velocity ratios. At sufficiently high strain-rate flames, these curves collapse into one curve; therefore, the flames follow the one-dimensional flame response of a typical diffusion flame. Low strain-rate flames are significantly affected by radial conductive heat loss, and therefore flame length. Three flame extinction modes are identified: flame extinction through shrinkage of the outer-edge flame with or without oscillations at the outer-edge flame prior to the extinction, and flame extinction through a flame hole at the flame center. The extinction modes are significantly affected by the behavior of the outer-edge flame. Detailed explanations are provided based on the measured flame-surface temperature and numerical evaluation of the fractional contribution of each term in the energy equation. Radial conductive heat loss at the flame edge to ambience is the main mechanism of extinction through shrinkage of the outer-edge flame in low strain-rate flames. Reduction of the burner diameter can extend the flame extinction mode by shrinking the outer-edge flame in higher strain-rate flames. © 2012 Elsevier Ltd. All rights reserved.

  10. Enhancement of turbulent flame speed of V-shaped flames in fractal-grid-generated turbulence

    NARCIS (Netherlands)

    Verbeek, A.A.; Willems, P.A.; Stoffels, G.G.M.; Geurts, B.J.; Meer, van der T.H.

    2016-01-01

    A variety of fractal grids is used to investigate how fractal-grid-generated turbulence affects the turbulent flame speed for premixed flames. The grids are placed inside a rectangular duct and a V-shaped flame is stabilized downstream of the duct, using a metal wire. This flame is characterized usi

  11. 33 CFR 154.822 - Detonation arresters, flame arresters, and flame screens.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Detonation arresters, flame arresters, and flame screens. 154.822 Section 154.822 Navigation and Navigable Waters COAST GUARD... BULK Vapor Control Systems § 154.822 Detonation arresters, flame arresters, and flame screens. (a)...

  12. Asymptotic analysis of outwardly propagating spherical flames

    Institute of Scientific and Technical Information of China (English)

    Yun-Chao Wu; Zheng Chen

    2012-01-01

    Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy.The spherical flame structure consists of the preheat zone,reaction zone,and equilibrium zone.Analytical solutions are separately obtained in these three zones and then asymptotically matched.In the asymptotic analysis,we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius.This correlation is compared with previous results derived in the limit of infinite value of activation energy.Based on this correlation,the properties of spherical flame propagation are investigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed.Moreover,the accuracy and performance of different models used in the spherical flame method are examined.It is found that in order to get accurate laminar flame speed and Markstein length,non-linear models should be used.

  13. Flame Retardants Used in Flexible Polyurethane Foam

    Science.gov (United States)

    The partnership project on flame retardants in furniture seeks to update the health and environmental profiles of flame-retardant chemicals that meet fire safety standards for upholstered consumer products with polyurethane foam

  14. Determination of reactivity parameters of model carbons, cokes and flame-chars

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst; Gjernes, Erik; Jessen, Thomas

    1996-01-01

    Reactivity profiles are defined and measured with thermogravimetry for a dense metallurgical Longyear coke, a polymer-derived porous active carbon, Carboxen 1000, and three flame-chars, Illinois #6, Pittsburgh #8 and New Mexico Blue #1. For each sample it is found that the reactivity profile can ...... reactivity measure is used to rank fuels with very different structural profiles, at varying levels of burnout, temperature and oxygen partial pressure. Keyword: TGA,Reactivity,Coal...

  15. Effects of AC Electric Field on Small Laminar Nonpremixed Flames

    KAUST Repository

    Xiong, Yuan

    2015-04-01

    Electric field can be a viable method in controlling various combustion properties. Comparing to traditional actuators, an application of electric field requires very small power consumption. Especially, alternating current (AC) has received attention recently, since it could modulate flames appreciably even for the cases when direct current (DC) has minimal effects. In this study, the effect of AC electric fields on small coflow diffusion flames is focused with applications of various laser diagnostic techniques. Flow characteristics of baseline diffusion flames, which corresponds to stationary small coflow diffusion flames when electric field is not applied, were firstly investigated with a particular focus on the flow field in near-nozzle region with the buoyancy force exerted on fuels due to density differences among fuel, ambient air, and burnt gas. The result showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle exit. Nozzle heating effect influenced this near-nozzle flow-field particularly among lighter fuels. Numerical simulations were also conducted and the results showed that a fuel inlet boundary condition with a fully developed velocity profile for cases with long fuel tubes should be specified inside the fuel tube to obtain satisfactory agreement in both the flow and temperature fields with those from experiment. With sub-critical AC applied to the baseline flames, particle image velocimetry (PIV), light scattering, laser-induced incandescence (LII), and laser-induced fluores- cence (LIF) techniques were adopted to identify the flow field and the structures of OH, polycyclic aromatic hydrocarbons (PAHs), soot zone. Under certain AC condi- tions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered from the

  16. Soot Formation and Destruction in High-Pressure Flames with Real Fuels

    Science.gov (United States)

    2013-08-18

    25 Figure 3.4.1: Optical setup for LOSA (A – aperture, IS – integrating sphere, L – lens, M – mirror, ND – neutral density Filter, NL...sight attenuation ( LOSA ) and laser scattering. Measurements were done in nitrogen-diluted ethylene flames at 4, 6, and 8 atm. LOSA measurements were... LOSA and scattering measurements of liquid-fuel flames are in progress. The LOSA results show the same pressure dependent trends of soot volume

  17. Firefighters and flame retardant activism.

    Science.gov (United States)

    Cordner, Alissa; Rodgers, Kathryn M; Brown, Phil; Morello-Frosch, Rachel

    2015-02-01

    In the past decade, exposure to flame retardant chemicals has become a pressing health concern and widely discussed topic of public safety for firefighters in the United States. Working through local, state, and national unions and independent health and advocacy organizations, firefighters have made important contributions to efforts to restrict the use of certain flame retardants. Firefighters are key members in advocacy coalitions dedicated to developing new environmental health regulations and reforming flammability standards to reflect the best available fire science. Their involvement has been motivated by substantiated health concerns and critiques of deceptive lobbying practices by the chemical industry. Drawing on observations and interviews with firefighters, fire safety experts, and other involved stakeholders, this article describes why firefighters are increasingly concerned about their exposure to flame retardant chemicals in consumer products, and analyzes their involvement in state and national environmental health coalitions.

  18. Microgravity experiments and numerical studies on ethanol/air spray flames

    Science.gov (United States)

    Thimothée, Romain; Chauveau, Christian; Halter, Fabien; Nicoli, Colette; Haldenwang, Pierre; Denet, Bruno

    2017-01-01

    Spray flames are known to exhibit amazing features in comparison with single-phase flames. The weightless situation offers the conditions in which the spray characteristics can be well controlled before and during combustion. The article reports on a joint experimental/numerical work that concerns ethanol/air spray flames observed in a spherical chamber using the condensation technique of expansion cooling (based on the Wilson cloud chamber principle), under microgravity. We describe the experimental set-up and give details on the creation of a homogeneous and nearly monosized aerosol. Different optical diagnostics are employed successfully to measure the relevant parameters of two-phase combustion. A classical shadowgraphy system is used to track the flame speed propagation and allow us to observe the flame front instability. The complete characterization of the aerosol is performed with a laser diffraction particle size analyser by measuring the droplet diameter and the droplet density number, just before ignition. A laser tomography device allows us to measure the temporal evolution of the droplet displacement during flame propagation, as well as to identify the presence of droplets in the burnt gases. The numerical modelling is briefly recalled. In particular, spray-flame propagation is schematized by the combustion spread in a 2-D lattice of fuel droplets surrounded by an initial gaseous mixture of fuel vapour and air. In its spherical expansion, the spray flame presents a corrugated front pattern, while the equivalent single-phase flame does not. From a numerical point of view, the same phenomena of wrinkles are also observed in the simulations. The front pattern pointed out by the numerical approach is identified as of Darrieus-Landau (DL) type. The droplets are found to trigger the instability. Then, we quantitatively compare experimental data with numerical predictions on spray-flame speed. The experimental results show that the spray-flame speed is of the

  19. Formulation, Pretreatment, and Densification Options to Improve Biomass Specifications for Co-Firing High Percentages with Coal

    Energy Technology Data Exchange (ETDEWEB)

    Jaya Shankar Tumuluru; J Richard Hess; Richard D. Boardman; Shahab Sokhansanj; Christopher T. Wright; Tyler L. Westover

    2012-06-01

    There is a growing interest internationally to use more biomass for power generation, given the potential for significant environmental benefits and long-term fuel sustainability. However, the use of biomass alone for power generation is subject to serious challenges, such as feedstock supply reliability, quality, and stability, as well as comparative cost, except in situations in which biomass is locally sourced. In most countries, only a limited biomass supply infrastructure exists. Alternatively, co-firing biomass alongwith coal offers several advantages; these include reducing challenges related to biomass quality, buffering the system against insufficient feedstock quantity, and mitigating the costs of adapting existing coal power plants to feed biomass exclusively. There are some technical constraints, such as low heating values, low bulk density, and grindability or size-reduction challenges, as well as higher moisture, volatiles, and ash content, which limit the co-firing ratios in direct and indirect co-firing. To achieve successful co-firing of biomass with coal, biomass feedstock specifications must be established to direct pretreatment options in order to modify biomass materials into a format that is more compatible with coal co-firing. The impacts on particle transport systems, flame stability, pollutant formation, and boiler-tube fouling/corrosion must also be minimized by setting feedstock specifications, which may include developing new feedstock composition by formulation or blending. Some of the issues, like feeding, co-milling, and fouling, can be overcome by pretreatment methods including washing/leaching, steam explosion, hydrothermal carbonization, and torrefaction, and densification methods such as pelletizing and briquetting. Integrating formulation, pretreatment, and densification will help to overcome issues related to physical and chemical composition, storage, and logistics to successfully co-fire higher percentages of biomass ( > 40

  20. Droplet and Supercritical Flame Dynamics in Propulsion

    Science.gov (United States)

    2010-03-26

    In order to study the stability of a lifted jet flame by nozzle-generated vortexes, we have developed a chemical explosive mode analysis ( CEMA ) to...runaway can consequently be distinguished. CEMA of the lifted flame shows the existence of two premixed flame fronts, which are difficult to detect

  1. Premixed flame propagation in vertical tubes

    Science.gov (United States)

    Kazakov, Kirill A.

    2016-04-01

    Analytical treatment of the premixed flame propagation in vertical tubes with smooth walls is given. Using the on-shell flame description, equations for a quasi-steady flame with a small but finite front thickness are obtained and solved numerically. It is found that near the limits of inflammability, solutions describing upward flame propagation come in pairs having close propagation speeds and that the effect of gravity is to reverse the burnt gas velocity profile generated by the flame. On the basis of these results, a theory of partial flame propagation driven by a strong gravitational field is developed. A complete explanation is given of the intricate observed behavior of limit flames, including dependence of the inflammability range on the size of the combustion domain, the large distances of partial flame propagation, and the progression of flame extinction. The role of the finite front-thickness effects is discussed in detail. Also, various mechanisms governing flame acceleration in smooth tubes are identified. Acceleration of methane-air flames in open tubes is shown to be a combined effect of the hydrostatic pressure difference produced by the ambient cold air and the difference of dynamic gas pressure at the tube ends. On the other hand, a strong spontaneous acceleration of the fast methane-oxygen flames at the initial stage of their evolution in open-closed tubes is conditioned by metastability of the quasi-steady propagation regimes. An extensive comparison of the obtained results with the experimental data is made.

  2. Acoustic power measurements of oscillating flames

    NARCIS (Netherlands)

    Valk, M.

    1981-01-01

    The acoustic power of an oscillating flame is measured. A turbulent premixed propane/air flame is situated near a pressure antinode of a standing wave in a laboratory combustion chamber. This standing wave is generated by a piston. The fluctuating heat release of the flame will supply acoustic power

  3. Hysteresis and transition in swirling nonpremixed flames

    NARCIS (Netherlands)

    Tummers, M.J.; Hübner, A.W.; Veen, van E.H.; Hanjalic, K.; Meer, van der Th.H.

    2009-01-01

    Strongly swirling nonpremixed flames are known to exhibit a hysteresis when transiting from an attached long, sooty, yellow flame to a short lifted blue flame, and vice versa. The upward transition (by increasing the air and fuel flow rates) corresponds to a vortex breakdown, i.e. an abrupt change f

  4. Acoustic power measurements of oscillating flames

    NARCIS (Netherlands)

    Valk, M.

    1981-01-01

    The acoustic power of an oscillating flame is measured. A turbulent premixed propane/air flame is situated near a pressure antinode of a standing wave in a laboratory combustion chamber. This standing wave is generated by a piston. The fluctuating heat release of the flame will supply acoustic power

  5. Environmental Considerations for Flame Resistant Textiles

    Science.gov (United States)

    Virtually all common textiles will ignite and burn. There are mandatory and voluntary cigarette and open-flame ignition regulations to address unreasonable fire risks associated with textile products that require them to be treated with and/or contain flame retardant chemicals to make them flame res...

  6. Cars Spectroscopy of Propellant Flames

    Science.gov (United States)

    1983-11-01

    Harris, K. Aron, and J. Fendell "N2 and 00 Vibrational CARS and H2 Rotational CARS Spectroscopy of CHI/N20 Flames," Proceedings of the Nineteenth...JANNAF Combustion Meeting, CIIA Publication No. 366, 1982, p 123. 21. K. Aron, L. E. Harris, and J. Fendell , "N and CO Vibrational CARS and H2 Rotational...9 6 5 . p 3 8 4 . . . . . 23. J. Fendell , L. E, Harris, and K. Aron, "Theoretical Calculation of 11 CARS S-Branches for Propellant Flames

  7. COAL GEOLOGY

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091749 Cai Hou’an(College of Energy Geology,China University of Geosciences,Beijing 100083,China);Xu Debin SHRIMP U-Pb Isotope Age of Volcanic Rocks Distributed in the Badaohao Area,Liaoning Province and Its Significance(Coal Geology & Exploration,ISSN1001-1986,CN61-1155/P,36(4),2008,p.17-20,2 illus.,1 table,16 refs.)Key words:coal measures,volcanic rocks,U-Pb dating,LiaoningA set of andesite volcanic rocks distributes in the Badaohao area in Heishan County,Liaoning Province.It’s geological age and stratigraphy sequence relationship between the Lower Cretaceous Badaohao Formation and the volcanic rocks can not make sure till now and is influencing the further prospect for coals.Zircon

  8. Experimental characterization of methane inverse diffusion flame

    KAUST Repository

    Elbaz, Ayman M.

    2014-06-26

    This article presents 10-kHz images of OH-PLIF simultaneously with 2-D PIV measurements in an inverse methane diffusion flame. Under a constant fuel flow rate, the central air jet Re was varied, leading to air to fuel velocity ratio, Vr, to vary from 8.3 to 66.5. Starting from Vr = 20.7, the flame is commonly characterized by three distinct zones. The length of the lower fuel entrainment region is inversely proportional to Vr. The flames investigated resemble a string shear layer confining this zone, and converging into the second distinct region, the flame neck zone. The third region is the rest of the flame, which spreads in a jet-like manner. The inverse diffusion flames exhibit varying degrees of partial premixing, depending upon on the velocity ratio Vr, and this region of partial premixing evolves into a well-mixed reaction zone along the flame centerline. The OH distribution correlated with the changes in the mean characteristics of the flow through reduction in the local Reynolds number due to heat release. The existence of a flame suppresses or laminarizes the turbulence at early axial locations and promotes fluctuations at the flame tip for flames with Vr < 49.8. In addition, the flame jet width can be correlated to the OH distribution. In upstream regions of the flames, the breaks in OH are counterbalanced by flame closures and are governed by edge flame propagation. These local extinctions were found to occur at locations where large flow structures were impinging on the flame and are associated with a locally higher strain rate or correlated to the local high strain rates at the flame hole edges without this flow impinging. Another contributor to re-ignition was found to be growing flame kernels. As the flames approach global blow-off, these kernels become the main mechanism for re-ignition further downstream of the flames. At low Vr, laminarization within the early regions of the flame provides an effective shield, preventing the jet flow from

  9. TOXIC SUBSTANCES FROM COAL COMBUSTION

    Energy Technology Data Exchange (ETDEWEB)

    A KOLKER; AF SAROFIM; CL SENIOR; FE HUGGINS; GP HUFFMAN; I OLMEZ; J LIGHTY; JOL WENDT; JOSEPH J HELBLE; MR AMES; N YAP; R FINKELMAN; T PANAGIOTOU; W SEAMES

    1998-12-08

    carried out during August at the Advanced Photon Source (APS), the new synchrotron facility at Argonne National Laboratory, Chicago, IL. Further analysis of small-scale combustion experiments conducted at PSI in Phase I was completed this quarter. The results of these experiments for the first time suggest almost complete vaporization of certain trace elements (Se, Zn) from coal combustion in the flame zone, in accordance with theoretical equilibrium predictions. Other elements (As, Sb, Cr) appeared considerably less volatile and may react with constituents in the bulk ash at combustion temperatures. The combustion section of the University of Arizona's Downflow Combustor was completely rebuilt. The University of Utah worked on setting up EPA Method 26A to give the capability to measure chlorine in flue gas. The chlorine kinetic calculations performed as part of the Phase I program were found to have an error in the initial conditions. Therefore, the calculations were re-done this quarter with the correct starting conditions. Development of a quasi-empirical emissions model based on reported emissions of particulate matter from field measurements was continued this quarter. As a first step in developing the ToPEM, we developed a sub-model that calculates the evaporation of major elements (Na, K, Fe, Si, Al, Ca and Mg) from both inherent and extraneous minerals of coal. During this quarter, this sub-model was included into EMAF, which formed the ToPEM. Experimental data from the Phase I program were used to test and modify the sub-model and the ToPEM.

  10. OPTIMIZATION OF COAL PARTICLE FLOW PATTERNS IN LOW NOX BURNERS

    Energy Technology Data Exchange (ETDEWEB)

    Jost O.L. Wendt; Gregory E. Ogden; Jennifer Sinclair; Caner Yurteri

    2001-08-20

    The proposed research is directed at evaluating the effect of flame aerodynamics on NO{sub x} emissions from coal fired burners in a systematic manner. This fundamental research includes both experimental and modeling efforts being performed at the University of Arizona in collaboration with Purdue University. The objective of this effort is to develop rational design tools for optimizing low NO{sub x} burners to the kinetic emissions limit (below 0.2 lb./MMBTU). Experimental studies include both cold and hot flow evaluations of the following parameters: flame holder geometry, secondary air swirl, primary and secondary inlet air velocity, coal concentration in the primary air and coal particle size distribution. Hot flow experiments will also evaluate the effect of wall temperature on burner performance. Cold flow studies will be conducted with surrogate particles as well as pulverized coal. The cold flow furnace will be similar in size and geometry to the hot-flow furnace but will be designed to use a laser Doppler velocimeter/phase Doppler particle size analyzer. The results of these studies will be used to predict particle trajectories in the hot-flow furnace as well as to estimate the effect of flame holder geometry on furnace flow field. The hot-flow experiments will be conducted in a novel near-flame down-flow pulverized coal furnace. The furnace will be equipped with externally heated walls. Both reactors will be sized to minimize wall effects on particle flow fields. The cold-flow results will be compared with Fluent computation fluid dynamics model predictions and correlated with the hot-flow results with the overall goal of providing insight for novel low NO{sub x} burner geometry's.

  11. Coal preparation and coal cleaning in the dry process; Kanshiki sentaku to coal cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Z.; Morikawa, M.; Fujii, Y. [Okayama University, Okayama (Japan). Faculty of Engineering

    1996-09-01

    Because the wet process has a problem such as waste water treatment, coal cleaning in the dry process was discussed. When a fluidized bed (using glass beads and calcium carbonate) is utilized instead of the heavy liquid, the fluidized bed will have apparent density as the liquid does, whereas the relative relationship therewith determines whether a substance having been put into the fluidized bed will float or sink. This is utilized for coals. In addition, two powder constituents of A and B may be wanted to be separated using the fluidized extraction process (similar to the liquid-liquid extraction process). In such a case, a fluidized bed in which both constituents are mixed is added with a third constituent C (which will not mix with A, but mix well with B), where the constituents are separated into A and (B + C), and the (B + C) constituent is separated further by using a sieve. If coal has the coal content mixed with ash content and pulverized, it turns into particle groups which have distributions in grain size and density. Groups having higher density may contain more ash, and those having lower density less ash. In addition, the ash content depends also on the grain size. The ash content may be classified by using simultaneously wind classification (for density and grain size) and a sieve (for grain size). This inference may be expanded to consideration of constructing a multi-stage fluidized bed classification tower. 12 figs., 5 tabs.

  12. A novel reutilization method for waste printed circuit boards as flame retardant and smoke suppressant for poly (vinyl chloride)

    Energy Technology Data Exchange (ETDEWEB)

    Xiu, Fu-Rong, E-mail: xiu_chem@hotmail.com [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350108 (China); Weng, Huiwei; Qi, Yingying; Yu, Gending; Zhang, Zhigang [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350108 (China); Zhang, Fu-Shen [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2016-09-05

    Highlights: • We report a novel electronic waste-based flame retardant for PVC. • The SCWO-treated PCBs significantly improves the flame retardancy of PVC. • The flame retardant mechanism of SCWO-treated PCBs was studied. • Appropriate amount flame retardant does not degrade the mechanical property of PVC. - Abstract: In this study, a novel reutilization method for waste printed circuit boards (PCBs) as flame retardant and smoke suppressant for poly (vinyl chloride) (PVC) was successfully testified. A supercritical water oxidation (SCWO) process was applied to treat waste PCBs before they could be used as flame retardants of PVC. The results indicated that SCWO conditions had a significant effect on the flame retarding and smoke suppressing properties of waste PCBs for PVC. Cu{sub 2}O, CuO, and SnO{sub 2} were the main active ingredients in waste PCBs-derived flame retardants. A conversion of Cu elements (Cu{sup 0} → Cu{sup +} → Cu{sup 2+}) during SCWO process with the increase of reaction temperature was found to be the key influence factor for the flame retarding properties of SCWO-treated PCBs. The experiment results also showed that there was a synergistic effect of flame retardancy between Cu{sup +} and Cu{sup 2+}. After the optimized SCWO treatment, SCWO-treated PCBs significantly improved the flame retardancy and smoke suppression of PVC. Limiting oxygen index (LOI) and char yield (CY) increased with increasing SCWO-treated PCBs content in PVC, while smoke density rating (SDR) and maximum smoke density (MSD) decreased markedly. The mechanical properties of PVC samples were influenced in different degree by adding different content SCWO-treated PCBs.

  13. Presumed PDF Modeling of Early Flame Propagation in Moderate to Intense Turbulence Environments

    Science.gov (United States)

    Carmen, Christina; Feikema, Douglas A.

    2003-01-01

    The present paper describes the results obtained from a one-dimensional time dependent numerical technique that simulates early flame propagation in a moderate to intense turbulent environment. Attention is focused on the development of a spark-ignited, premixed, lean methane/air mixture with the unsteady spherical flame propagating in homogeneous and isotropic turbulence. A Monte-Carlo particle tracking method, based upon the method of fractional steps, is utilized to simulate the phenomena represented by a probability density function (PDF) transport equation. Gaussian distributions of fluctuating velocity and fuel concentration are prescribed. Attention is focused on three primary parameters that influence the initial flame kernel growth: the detailed ignition system characteristics, the mixture composition, and the nature of the flow field. The computational results of moderate and intense isotropic turbulence suggests that flames within the distributed reaction zone are not as vulnerable, as traditionally believed, to the adverse effects of increased turbulence intensity. It is also shown that the magnitude of the flame front thickness significantly impacts the turbulent consumption flame speed. Flame conditions studied have fuel equivalence ratio s in the range phi = 0.6 to 0.9 at standard temperature and pressure.

  14. Imaging Invisible Flames Without Additives

    Science.gov (United States)

    Weiland, Karen J.

    1996-01-01

    Image intensifiers, video cameras, and image-data-processing computers used to study combustion. Possible to view and analyze methane, hydrogen, and other flames dim or invisible to human eye and difficult to image by use of conventional photographic and video cameras.

  15. Olympic Flame Burning In Athens

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正>At 6:00pm March 25 (Beijing time), 2004 Athens Olympic flame was lit in Greece’s ancient sanctuary, indicating that the torch relay started.The torch relay, established at the Berlin Games in 1936, will for the first time visit all five continents

  16. The VLT FLAMES Tarantula Survey

    NARCIS (Netherlands)

    Evans, C.; Taylor, W.; Sana, H.; Hénault-Brunet, V.; Bagnoli, T.; Bastian, N.; Bestenlehner, J.; Bonanos, A.; Bressert, E.; Brott, I.; Campbell, M.; Cantiello, M.; Carraro, G.; Clark, S.; Costa, E.; Crowther, P.; de Koter, A.; de Mink, S.; Doran, E.; Dufton, P.; Dunstall, P.; Garcia, M.; Gieles, M.; Gräfener, G.; Herrero, A.; Howarth, I.; Izzard, R.; Köhler, K.; Langer, N.; Lennon, D.; Maíz Apellániz, J.; Markova, N.; Najarro, P.; Puls, J.; Ramirez, O.; Sabín-Sanjulián, C.; Simón-Díaz, S.; Smartt, S.; Stroud, V.; van Loon, J.; Vink, J.S.; Walborn, N.

    2011-01-01

    We introduce the VLT FLAMES Tarantula Survey, an ESO Large Programme from which we have obtained optical spectroscopy of over 800 massive stars in the spectacular 30 Doradus region of the Large Magellanic Cloud. A key feature is the use of multi-epoch observations to provide strong constraints on

  17. Flame monitoring enhances burner management

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, T.; Bailey, R.; Fuller, T.; Daw, S.; Finney, C.; Stallings, J. [Babcock & Wilcox Research Center (USA)

    2003-02-01

    A new burner monitoring and diagnostic system called Flame Doctor offers users a more precise and discriminating understanding of burner conditions. Alpha testing on Unit 4 at AmerenUE's Meramec power plant in St. Louis, MO, USA and Beta testing is underway at plants owned by Dynegy and Allegheny Energy. 6 refs., 3 figs.

  18. Enhancements of Impinging Flame by Pulsation

    Institute of Scientific and Technical Information of China (English)

    AySu; Ying-ChiehLiu

    2000-01-01

    Experimental investigations on the pulsating jet-impinging diffusion flame were executed.A soleoid valve was aligned upstream of the jet orifice and the methane fuel was controlled in open-closed cycles from 0 Hz to 20Hz.Results show that the open-closed cycles,indeed increase the fluctuations of the methane fuel obviously.The evolutions of pulsating flame therefore develop faster than the continuous impinging flame.The optimized pulating frequencies are near 9 to 11 hz from the Re=170 to 283.The temperature differences between that under optimized pulsating rate and full open condition(no pulsation)are ranging from 100 to 150 degree.The pulsating effect is more singnificant at low Reynolds number.The cross section of continuous impinging flame behaves as elliptic shape with axial ratio equals to 2/3.The tip of the impinging flame obviously crosses at 42mm above the impinging point.ecause of the phenomenon of pulsation flame,the flame sheet or flame front may not be identified clearly in the averaged temperature contours.Results shows that the averaged end-contour of pulsation flame rears at 38mm above the impinging point.By observation and experiment,the pulsating flame behaves more stable and efficient than the continuous impinging flame.

  19. Turbulent Oxygen Flames in Type Ia Supernovae

    CERN Document Server

    Aspden, A J; Woosley, S E; 10.1088/0004-637X/730/2/144

    2011-01-01

    In previous studies, we examined turbulence-flame interactions in carbon-burning thermonuclear flames in Type Ia supernovae. In this study, we consider turbulence-flame interactions in the trailing oxygen flames. The two aims of the paper are to examine the response of the inductive oxygen flame to intense levels of turbulence, and to explore the possibility of transition to detonation in the oxygen flame. Scaling arguments analogous to the carbon flames are presented and then compared against three-dimensional simulations for a range of Damk\\"ohler numbers ($\\Da_{16}$) at a fixed Karlovitz number. The simulations suggest that turbulence does not significantly affect the oxygen flame when $\\Da_{16}1$, turbulence enhances heat transfer and drives the propagation of a flame that is {\\em narrower} than the corresponding inductive flame would be. Furthermore, burning under these conditions appears to occur as part of a combined carbon-oxygen turbulent flame with complex compound structure. The simulations do not ...

  20. Sooting limit of a double diffusion flame

    Energy Technology Data Exchange (ETDEWEB)

    Kitano, Michio; Kobayashi, Hideaki; Nishiki, Nobuhiko (Tohoku Univ., Faculty of Engineering, Sendai, Japan Sony Corp., Tokyo (Japan))

    1989-07-25

    The soot exhaust from the flame of pot type burner for the domestic heating use was basically studied. Inside a fuel (secondary) diffusion flame in air atmosphere, which was an ordinary diffusion flame, an air (primary) diffusion flame in fuel atmosphere, which was reverse in relation between them, was formed by using propane fuel. For the sooting limit of that double diffusion flame, the effect of primary air ratio, distance between primary and secondary flames, thermal condition on wall surface and flow stretch being investigated by use of three different types of burner, the double diffusion flame method was studied in effectiveness on the soot exhaust and known to heighten the control against it, which heightening however depended in degree upon the locative relation between both the flames. The control was more heightened with a more lengthening in the secondary flame. Because the sooting limit is governed by the secondary flame temperature, the establishment of condition so as to heighten the flame temperature is necessary for the effective control against the soot exhaust. 11 refs., 11 figs.

  1. The effect of imported coals and coal blends on grinding and combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Maier, H.; Rebmann, M.; Fingerle, A.; Hein, K.R.G. [University of Stuttgart, Stuttgart (Germany). Inst.-IVD

    1998-12-31

    The European Union is one of the biggest regions importing bituminous coal from overseas areas and countries like South Africa, Australia, Colombia, North America, and Indonesia/Asia. The use of these coals can raise specific problems with regard to the milling and combustion behaviour. In this project the following facilities were used for the test trials; a 120 kg/h impact milling system to investigate the milling behaviour; the 0.5 MW{sub th} IVD semi-industrial scale pulverised combustion chamber for the combustion studies and; a 80 kW{sub th} turbulent natural gas free jet burner, for the characterisation studies. The results concerning the milling behaviour show that most of the tested coals and coal blending the Hardgrove Index is a measure to determine the grindability on laboratory scale but also not generally valid. The coal characterization studies with the turbulent gas burner show that the heat up-rate and the devolatilization of the volatiles is comparable to those in full scale coal flames. The volatile release is about 10 times faster compared to values determined with electricity heated flow reactors. 11 refs., 33 figs., 5 tabs.

  2. Flame Reconstruction Using Synthetic Aperture Imaging

    CERN Document Server

    Murray, Preston; Tree, Dale; Truscott, Tadd

    2011-01-01

    Flames can be formed by burning methane (CH4). When oxygen is scarce, carbon particles nucleate into solid particles called soot. These particles emit photons, making the flame yellow. Later, methane is pre-mixed with air forming a blue flame; burning more efficiently, providing less soot and light. Imaging flames and knowing their temperature are vital to maximizing efficiency and validating numerical models. Most temperature probes disrupt the flame and create differences leading to an inaccurate measurement of the flame temperature. We seek to image the flame in three dimensions using synthetic aperture imaging. This technique has already successfully measured velocity fields of a vortex ring [1]. Synthetic aperture imaging is a technique that views one scene from multiple cameras set at different angles, allowing some cameras to view objects that are obscured by others. As the resulting images are overlapped different depths of the scene come into and out of focus, known as focal planes, similar to tomogr...

  3. Flex-flame burner and combustion method

    Science.gov (United States)

    Soupos, Vasilios; Zelepouga, Serguei; Rue, David M.; Abbasi, Hamid A.

    2010-08-24

    A combustion method and apparatus which produce a hybrid flame for heating metals and metal alloys, which hybrid flame has the characteristic of having an oxidant-lean portion proximate the metal or metal alloy and having an oxidant-rich portion disposed above the oxidant lean portion. This hybrid flame is produced by introducing fuel and primary combustion oxidant into the furnace chamber containing the metal or metal alloy in a substoichiometric ratio to produce a fuel-rich flame and by introducing a secondary combustion oxidant into the furnace chamber above the fuel-rich flame in a manner whereby mixing of the secondary combustion oxidant with the fuel-rich flame is delayed for a portion of the length of the flame.

  4. Coal industry annual 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    Coal Industry Annual 1997 provides comprehensive information about US coal production, number of mines, prices, productivity, employment, productive capacity, and recoverable reserves. US Coal production for 1997 and previous years is based on the annual survey EIA-7A, Coal Production Report. This report presents data on coal consumption, coal distribution, coal stocks, coal prices, and coal quality for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States. This report includes a national total coal consumption for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. 14 figs., 145 tabs.

  5. Coal Industry Annual 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-10-01

    This report presents data on coal consumption, coal distribution, coal stocks, coal prices, coal quality, and emissions for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States. This report does not include coal consumption data for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. Consumption for nonutility power producers not included in this report is estimated to be 21 million short tons for 1995.

  6. Coal industry annual 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-11-01

    This report presents data on coal consumption, coal distribution, coal stocks, coal prices, and coal quality, and emissions for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States.This report does not include coal consumption data for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. Consumption for nonutility power producers not included in this report is estimated to be 24 million short tons for 1996. 14 figs., 145 tabs.

  7. The discrete regime of flame propagation

    Science.gov (United States)

    Tang, Francois-David; Goroshin, Samuel; Higgins, Andrew

    The propagation of laminar dust flames in iron dust clouds was studied in a low-gravity envi-ronment on-board a parabolic flight aircraft. The elimination of buoyancy-induced convection and particle settling permitted measurements of fundamental combustion parameters such as the burning velocity and the flame quenching distance over a wide range of particle sizes and in different gaseous mixtures. The discrete regime of flame propagation was observed by substitut-ing nitrogen present in air with xenon, an inert gas with a significantly lower heat conductivity. Flame propagation in the discrete regime is controlled by the heat transfer between neighbor-ing particles, rather than by the particle burning rate used by traditional continuum models of heterogeneous flames. The propagation mechanism of discrete flames depends on the spa-tial distribution of particles, and thus such flames are strongly influenced by local fluctuations in the fuel concentration. Constant pressure laminar dust flames were observed inside 70 cm long, 5 cm diameter Pyrex tubes. Equally-spaced plate assemblies forming rectangular chan-nels were placed inside each tube to determine the quenching distance defined as the minimum channel width through which a flame can successfully propagate. High-speed video cameras were used to measure the flame speed and a fiber optic spectrometer was used to measure the flame temperature. Experimental results were compared with predictions obtained from a numerical model of a three-dimensional flame developed to capture both the discrete nature and the random distribution of particles in the flame. Though good qualitative agreement was obtained between model predictions and experimental observations, residual g-jitters and the short reduced-gravity periods prevented further investigations of propagation limits in the dis-crete regime. The full exploration of the discrete flame phenomenon would require high-quality, long duration reduced gravity environment

  8. A flame particle tracking analysis of turbulence–chemistry interaction in hydrogen–air premixed flames

    KAUST Repository

    Uranakara, Harshavardhana A.

    2015-11-21

    Interactions of turbulence, molecular transport, and energy transport, coupled with chemistry play a crucial role in the evolution of flame surface geometry, propagation, annihilation, and local extinction/re-ignition characteristics of intensely turbulent premixed flames. This study seeks to understand how these interactions affect flame surface annihilation of lean hydrogen–air premixed turbulent flames. Direct numerical simulations (DNSs) are conducted at different parametric conditions with a detailed reaction mechanism and transport properties for hydrogen–air flames. Flame particle tracking (FPT) technique is used to follow specific flame surface segments. An analytical expression for the local displacement flame speed (Sd) of a temperature isosurface is considered, and the contributions of transport, chemistry, and kinematics on the displacement flame speed at different turbulence-flame interaction conditions are identified. In general, the displacement flame speed for the flame particles is found to increase with time for all conditions considered. This is because, eventually all flame surfaces and their resident flame particles approach annihilation by reactant island formation at the end of stretching and folding processes induced by turbulence. Statistics of principal curvature evolving in time, obtained using FPT, suggest that these islands are ellipsoidal on average enclosing fresh reactants. Further examinations show that the increase in Sd is caused by the increased negative curvature of the flame surface and eventual homogenization of temperature gradients as these reactant islands shrink due to flame propagation and turbulent mixing. Finally, the evolution of the normalized, averaged, displacement flame speed vs. stretch Karlovitz number are found to collapse on a narrow band, suggesting that a unified description of flame speed dependence on stretch rate may be possible in the Lagrangian description.

  9. The impact of combustion characteristics and flame structure on soot formation in oxy-enhanced and oxy-fuel diffusion flames

    Institute of Scientific and Technical Information of China (English)

    GUO; Zhe; LOU; Chun; LIU; ZhengDong; ZHOU; HuaiChun

    2013-01-01

    Based on a detailed chemical mechanism, impacts of combustion characteristics and flame structure on soot formation in opposed-flow diffusion ethylene flames was studied with different stoichiometric mixture fractions in O2/N2and O2/CO2atmospheres. The results showed the followings. 1) In both atmospheres, with the increase of stoichiometric mixture fraction, the flame structure changed significantly. The stagnation plane shifted toward the oxidizer side. Furthermore, there were less C2H2 but more O and OH to occur in the soot inception zone, therefore the amount of soot in the flame decreased. 2) Compared withN2, CO2had a suppression effect on soot formation, which was mainly due to thermal and direct chemical interaction effects of CO2. This is because the specific heat capacity of CO2is higher than that of N2, which will cause the flame temperature to drop,and mole fractions of C2H2, H, O, OH and main PAHs to decrease. Soot oxidation played a dominant role, while soot surface growth was attributed to the secondary position. Meanwhile, when CO2 abounded in the flame, OH concentration was increased through the backward reaction of CO+OH=CO2+H, and this would be conducive to the oxidation of soot precursor and incipient soot particles. In addition, the results of maximum particle density indicated the thermal effect of CO2on soot for-mation is more important than the direct chemical interaction effect.

  10. Studies on the effect of coal properties on pulverised coal fired boiler performance operating with advanced low NO{sub x} technologies

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, D.J.; Kamp, W.L. van de [International Flame Research Foundation, IJmuiden (Netherlands)

    1998-12-31

    Reburning or fuel staging is a technology that can be applied as a retro-fit to burners as a means of reducing NO{sub x} emissions. This report concentrates on using existing knowledge of reburning techniques, with the aim of developing an Integrated Fuel Staged Burner whereby the reburning fuel can be introduced within the burner itself. The investigations were conducted in a simulated boiler chamber with internal dimensions of 2 x 2 x 6.3 m. The single burner experiments were performed with Gottelborn (HVB), El Cerejon (HVB), Middelburg (MVB), Klein Kopje (MVB) and Polish coal (HVB). The experiments were conducted at the scale of 2.5 MW{sub t} with a swirl stabilised Internally Fuel Staged Burner (IFSB). The primary fuel was a bituminous coal of either high or medium volatile content and the reburning fuels were natural gas or a bituminous coal, again with a high or medium volatile content. The reburn fuel fraction varied from 0% to 40% on a fuel input basis. The main parameters affecting emissions of NO{sub x} and burnout were the primary zone stoichiometry, reburn fuel fraction, tertiary air position, coal type and flame type. With reburning conditions of 20% gas (reburn fuel)/80% coal (primary fuel) NO{sub x} could be reduced in the range 55 to {approximately} 78%, relative to a baseline 100% coal flame, depending on the location of the tertiary air and coal type. Coal over coal reburning led to reduced concentrations of NO{sub x} relative to the baseline flames, but increased concentrations compared to conditions where natural gas was used as the reburn fuel, which is consistent with the higher concentration of fuel-bound nitrogen. 16 refs., 22 figs., 7 tabs.

  11. Direct numerical simulations of type Ia supernovae flames I: The landau-darrieus instability

    Energy Technology Data Exchange (ETDEWEB)

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2003-11-24

    Planar flames are intrinsically unstable in open domains due to the thermal expansion across the burning front--the Landau-Darrieus instability. This instability leads to wrinkling and growth of the flame surface, and corresponding acceleration of the flame, until it is stabilized by cusp formation. We look at the Landau-Darrieus in stability for C/O thermonuclear flames at conditions relevant to the late stages of a Type Ia supernova explosion. Two-dimensional direct numerical simulations of both single-mode and multi-mode perturbations using a low Mach number hydrodynamics code are presented. We show the effect of the instability on the flame speed as a function of both the density and domain size, demonstrate the existence of the small scale cutoff to the growth of the instability, and look for the proposed breakdown of the non-linear stabilization at low densities. The effects of curvature on the flame as quantified through measurements of the growth rate and computation of the corresponding Markstein number. While accelerations of a few percent are observed, they are too small to have any direct outcome on the supernova explosion.

  12. Direct Numerical Simulations of Type Ia Supernovae Flames I: The Landau-Darrieus Instability

    CERN Document Server

    Bell, J B; Rendleman, C A; Woosley, S E; Zingale, M A

    2004-01-01

    Planar flames are intrinsically unstable in open domains due to the thermal expansion across the burning front--the Landau-Darrieus instability. This instability leads to wrinkling and growth of the flame surface, and corresponding acceleration of the flame, until it is stabilized by cusp formation. We look at the Landau-Darrieus instability for C/O thermonuclear flames at conditions relevant to the late stages of a Type Ia supernova explosion. Two-dimensional direct numerical simulations of both single-mode and multi-mode perturbations using a low Mach number hydrodynamics code are presented. We show the effect of the instability on the flame speed as a function of both the density and domain size, demonstrate the existence of the small scale cutoff to the growth of the instability, and look for the proposed breakdown of the non-linear stabilization at low densities. The effects of curvature on the flame as quantified through measurements of the growth rate and computation of the corresponding Markstein numb...

  13. Direct simulation and modeling of flame-wall interaction for premixed turbulent combustion

    Energy Technology Data Exchange (ETDEWEB)

    Poinsot, T.J.; Haworth, D.C.; Bruneaux, G. (CNRS, Toulouse (France). Inst. de Mecanique des Fluides de Toulouse General Motors Research, Warren, MI (United States) Inst. Francais du Petrole, Rueil Malmaison (France))

    1993-10-01

    The interaction between turbulent premixed flames and walls is studied using a two-dimensional full Navier-Stokes solver with simple chemistry. The effects of wall distance on the local and global flame structure are investigated. Quenching distances and maximum wall heat fluxes during quenching are computed in laminar cases and are found to be comparable to experimental and analytical results. For turbulent cases, it is shown that quenching distances and maximum heat fluxes remain of the same order as for laminar flames. Based on simulation results, a law-of-the-wall'' model is derived to describe the interaction between a turbulent premixed flame and a wall. This model is constructed to provide reasonable behavior of flame surface density near a wall under the assumption that flame -- wall interaction takes place at scales smaller than the computational mesh. It can be implemented in conjunction with any of several recent flamelet models based on a modeled surface density equation, with no additional constraints on mesh size or time step. Preliminary tests of this model are presented for the case of a spark-ignited piston engine.

  14. DNS and modeling of the interaction between turbulent premixed flames and walls

    Science.gov (United States)

    Poinsot, T. J.; Haworth, D. C.

    1992-01-01

    The interaction between turbulent premixed flames and walls is studied using a two-dimensional full Navier-Stokes solver with simple chemistry. The effects of wall distance on the local and global flame structure are investigated. Quenching distances and maximum wall heat fluxes during quenching are computed in laminar cases and are found to be comparable to experimental and analytical results. For turbulent cases, it is shown that quenching distances and maximum heat fluxes remain of the same order as for laminar flames. Based on simulation results, a 'law-of-the-wall' model is derived to describe the interaction between a turbulent premixed flame and a wall. This model is constructed to provide reasonable behavior of flame surface density near a wall under the assumption that flame-wall interaction takes place at scales smaller than the computational mesh. It can be implemented in conjunction with any of several recent flamelet models based on a modeled surface density equation, with no additional constraints on mesh size or time step.

  15. An Investigation of a Hybrid Mixing Model for PDF Simulations of Turbulent Premixed Flames

    Science.gov (United States)

    Zhou, Hua; Li, Shan; Wang, Hu; Ren, Zhuyin

    2015-11-01

    Predictive simulations of turbulent premixed flames over a wide range of Damköhler numbers in the framework of Probability Density Function (PDF) method still remain challenging due to the deficiency in current micro-mixing models. In this work, a hybrid micro-mixing model, valid in both the flamelet regime and broken reaction zone regime, is proposed. A priori testing of this model is first performed by examining the conditional scalar dissipation rate and conditional scalar diffusion in a 3-D direct numerical simulation dataset of a temporally evolving turbulent slot jet flame of lean premixed H2-air in the thin reaction zone regime. Then, this new model is applied to PDF simulations of the Piloted Premixed Jet Burner (PPJB) flames, which are a set of highly shear turbulent premixed flames and feature strong turbulence-chemistry interaction at high Reynolds and Karlovitz numbers. Supported by NSFC 51476087 and NSFC 91441202.

  16. Coal-based carbon foams. Influence of the precursor coal

    Energy Technology Data Exchange (ETDEWEB)

    Montserrat Calvo; Roberto Garcia; Sabino R. Moinelo [Instituto Nacional del Carbon (CSIC), Oviedo (Spain)

    2007-07-01

    Carbon foams were obtained from several bituminous coals with different plasticity and volatile matter content by a two-stage thermal process. The first stage, a controlled carbonisation treatment under pressure at 450-500{sup o}C, is responsible for the final textural properties of the foam. In the second stage the carbonisation product was baked at 1100{sup o}C. The foams produced display a macroporous texture with plasticity, volatile matter content and maceral composition of the precursor coals having an influence on the apparent density and the pore size of the resultant porous products. 7 refs., 4 figs., 3 tabs.

  17. Nonlinear hydrodynamic and thermoacoustic oscillations of a bluff-body stabilised turbulent premixed flame

    Science.gov (United States)

    Lee, Chin Yik; Li, Larry Kin Bong; Juniper, Matthew P.; Cant, Robert Stewart

    2016-01-01

    Turbulent premixed flames often experience thermoacoustic instabilities when the combustion heat release rate is in phase with acoustic pressure fluctuations. Linear methods often assume a priori that oscillations are periodic and occur at a dominant frequency with a fixed amplitude. Such assumptions are not made when using nonlinear analysis. When an oscillation is fully saturated, nonlinear analysis can serve as a useful avenue to reveal flame behaviour far more elaborate than period-one limit cycles, including quasi-periodicity and chaos in hydrodynamically or thermoacoustically self-excited system. In this paper, the behaviour of a bluff-body stabilised turbulent premixed propane/air flame in a model jet-engine afterburner configuration is investigated using computational fluid dynamics. For the frequencies of interest in this investigation, an unsteady Reynolds-averaged Navier-Stokes approach is found to be appropriate. Combustion is represented using a modified laminar flamelet approach with an algebraic closure for the flame surface density. The results are validated by comparison with existing experimental data and with large eddy simulation, and the observed self-excited oscillations in pressure and heat release are studied using methods derived from dynamical systems theory. A systematic analysis is carried out by increasing the equivalence ratio of the reactant stream supplied to the premixed flame. A strong variation in the global flame structure is observed. The flame exhibits a self-excited hydrodynamic oscillation at low equivalence ratios, becomes steady as the equivalence ratio is increased to intermediate values, and again exhibits a self-excited thermoacoustic oscillation at higher equivalence ratios. Rich nonlinear behaviour is observed and the investigation demonstrates that turbulent premixed flames can exhibit complex dynamical behaviour including quasiperiodicity, limit cycles and period-two limit cycles due to the interactions of various

  18. An important missing source of atmospheric carbonyl sulfide: Domestic coal combustion

    Science.gov (United States)

    Du, Qianqian; Zhang, Chenglong; Mu, Yujing; Cheng, Ye; Zhang, Yuanyuan; Liu, Chengtang; Song, Min; Tian, Di; Liu, Pengfei; Liu, Junfeng; Xue, Chaoyang; Ye, Can

    2016-08-01

    Carbonyl sulfide (COS), carbon monoxide (CO), and sulfur dioxide (SO2) emissions generated from prevailing domestic coal stoves fueled with raw bituminous coal were studied under alternation cycles of flaming and smoldering combustion. The measurements in the laboratory and the farmer's house indicated that COS and CO emissions mainly occurred under the condition of flame extinguishment after coal loading, whereas SO2 emissions were mainly generated through combustion with flame. The COS emission factors for the domestic stoves in the laboratory and the farmer's house were recorded as 0.57 ± 0.10 g COS kg-1 and 1.43 ± 0.32 g COS kg-1, being approximately a factor of 50 and 125 greater than that generated from coal power plants, respectively. Based on the COS emission factors measured in this study, COS emission from only domestic coal combustion in China would be at least 30.5 ± 5.6 Gg S yr-1 which was 1 magnitude greater than the current COS estimation from the total coal combustion in China.

  19. Numerical simulation of tulip flame dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Cloutman, L.D.

    1991-11-30

    A finite difference reactive flow hydrodynamics program based on the full Navier-Stokes equations was used to simulate the combustion process in a homogeneous-charge, constant-volume combustion bomb in which an oddly shaped flame, known as a ``tulip flame`` in the literature, occurred. The ``tulip flame`` was readily reproduced in the numerical simulations, producing good agreement with the experimental flame shapes and positions at various times. The calculations provide sufficient detail about the dynamics of the experiment to provide some insight into the physical mechanisms responsible for the peculiar flame shape. Several factors seem to contribute to the tulip formation. The most important process is the baroclinic production of vorticity by the flame front, and this rate of production appears to be dramatically increased by the nonaxial flow generated when the initial semicircular flame front burns out along the sides of the chamber. The vorticity produces a pair of vortices behind the flame that advects the flame into the tulip shape. Boundary layer effects contribute to the details of the flame shape next to the walls of the chamber, but are otherwise not important. 24 refs.

  20. Numerical simulation of tulip flame dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Cloutman, L.D.

    1991-11-30

    A finite difference reactive flow hydrodynamics program based on the full Navier-Stokes equations was used to simulate the combustion process in a homogeneous-charge, constant-volume combustion bomb in which an oddly shaped flame, known as a tulip flame'' in the literature, occurred. The tulip flame'' was readily reproduced in the numerical simulations, producing good agreement with the experimental flame shapes and positions at various times. The calculations provide sufficient detail about the dynamics of the experiment to provide some insight into the physical mechanisms responsible for the peculiar flame shape. Several factors seem to contribute to the tulip formation. The most important process is the baroclinic production of vorticity by the flame front, and this rate of production appears to be dramatically increased by the nonaxial flow generated when the initial semicircular flame front burns out along the sides of the chamber. The vorticity produces a pair of vortices behind the flame that advects the flame into the tulip shape. Boundary layer effects contribute to the details of the flame shape next to the walls of the chamber, but are otherwise not important. 24 refs.

  1. The initial development of a tulip flame

    Energy Technology Data Exchange (ETDEWEB)

    Matalon, M.; Mcgreevy, J.L. [Northwestern Univ., Evanston, IL (United States)

    1994-12-31

    The initial development of a ``tulip flame``, often observed during flame propagation in closed tubes, is attributed to a combustion instability. The roles of hydrodynamic and of the diffusional-thermal processes on the onset of instability are investigated through a linear stability analysis in which the growth or decay of small disturbances, superimposed on an otherwise smooth and planar flame front, are followed. A range of the Markstein parameter, related to the mixture composition through an appropriately defined Lewis number, has been identified where a tulip flame could be observed. For a given value of the Markstein parameter within this range, a critical wavelength is identified as the most unstable mode. This wavelength is directly related to the minimal aspect ratio of the tube where a tulip flame could be observed. The time of onset of instability is identified as the time when the most unstable disturbance, associated with the critical wavelength, grows at a faster rate than the flame front itself and exceeds a certain threshold. This occurs after the flame has propagated a certain distance down the tube: a value which has been explicitly determined in terms of the relevant parameters. Experimental records on the tulip flame phenomenon support the finding of the analysis. That is, the tulip flame forms after the flame has traveled half the tube`s length, it does not form in short tubes, and its formation depends on the mixture composition and on the initial pressure in the tube.

  2. Coal industry annual 1993

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-06

    Coal Industry Annual 1993 replaces the publication Coal Production (DOE/FIA-0125). This report presents additional tables and expanded versions of tables previously presented in Coal Production, including production, number of mines, Productivity, employment, productive capacity, and recoverable reserves. This report also presents data on coal consumption, coal distribution, coal stocks, coal prices, coal quality, and emissions for a wide audience including the Congress, Federal and State agencies, the coal industry, and the general public. In addition, Appendix A contains a compilation of coal statistics for the major coal-producing States. This report does not include coal consumption data for nonutility Power Producers who are not in the manufacturing, agriculture, mining, construction, or commercial sectors. This consumption is estimated to be 5 million short tons in 1993.

  3. Coal - proximate analysis

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-06-14

    This Standard establishes a practice for the proximate analysis of coal, that is, the coal is analysed for the content of moisture, ash and volatile matter; fixed carbon is calculated. The standard provides a basis for the comparison of coals.

  4. Occurrence of coal and coal-derived particle-bound polycyclic aromatic hydrocarbons (PAHs) in a river floodplain soil.

    Science.gov (United States)

    Yang, Yi; Ligouis, Bertrand; Pies, Carmen; Grathwohl, Peter; Hofmann, Thilo

    2008-01-01

    A PAH contaminated river floodplain soil was separated according to grain size and density. Coal and coal-derived particles from coal mining, coal industry and coal transportation activities were identified by organic petrographic analysis in our samples. Distinct concentrations of PAHs were found in different grain size and density fractions, however, similar distribution patterns of PAHs indicated similar sources. In addition, although light fractions had the mass fraction by weight of less than 5%, they contributed almost 75% of the total PAHs in the soil. PAH concentrations of all sub fractions showed positive correlation with their TOC contents. Altogether, coal and coal-derived particles that were abundant in light fractions could be the dominant geosorbents for PAHs in our samples.

  5. The use of mechanically activated micronized coal in thermal power engineering

    Directory of Open Access Journals (Sweden)

    Burdukov Anatoliy P.

    2016-01-01

    Full Text Available Coal is one of the main energy resources and development of new promising technologies on its basis is certainly topical. This article discusses the use of new technology of gas and fuel oil replacement by mechanically activated micronized coal in power engineering: ignition and stabilization of pulverized coal flame combustion, as well as gasification of micronized coal in the flow. The new technology coal combustion with two stages of grinding is suggested. Optimization of the scheme of two-stage combustion is calculated. The first experimental data on the combustion process are obtained. The first demonstration tests on gas and heavy oil replacement by micronized coal during boiler ignition were carried out in the real power boiler with the capacity of 320 tons of steam per hour.

  6. Influence of obstacle disturbance in a duct on explosion characteristics of coal gas

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In combination with experimental research,numerical simulation is performed to investigate the influence law of the obstacles in a duct on the explosion flame of premixed coal gas and air. The numerical method uses upwind WENO scheme and two-step chemical reaction model. The interaction mechanism is addressed between the compression wave from reflection on the right end of the duct and flame propagation. The reflected wave is found to result in the decrease of flame velocity. On this basis,we analyze the mechanism of the obstacles on flame as well as the law of flow field variation thus caused. The results suggest that,due to the obstacles,deflagration wave is repeatedly reflected,combustible gas mixture is fully compressed,temperature and pressure rise,chemical reaction speed increases,and hence flame intensity is strengthened. At the same time,a tripe point forms as a result of wall reflection of the deflagration wave from the obstacles and furthermore local flame speed increases. As the triple point propagates forward,the flame speed gradually decreases due to dissipation of energy. These conclusions provide a valuable theoretical foundation for the prediction of explosion field,prevention of fire and explosion and effective control of the com-bustion speed and flame propagation speed in detonation propulsion.

  7. Comparison of coal separation characteristics based on different separating approaches in dry coal beneficiation flowsheet

    Institute of Scientific and Technical Information of China (English)

    HE Jing-feng; ZHAO Yue-min; HE Ya-qun; LUO Zhen-fu; DUAN Chen-long

    2015-01-01

    The separation characteristic of raw coal from Luoyang mining area, China, was investigated by applying a dry coal beneficiation flowsheet with the dense medium gas-solid fluidized bed as main separating equipment. The experimental and simulation results indicate that the dense medium gas-solid fluidized bed can provide uniform distribution and stable fluctuation of bed densities at various heights. Two types of different separating approaches were compared using the dry coal beneficiation flowsheet. Compared with obtaining cleaning coal in the first stage of the flowsheet, a higher yield of the cleaning coal and better separation efficiency can be achieved when discharging gangue in the first stage. Finally, the results indicate that 64.86% pure cleaning coal with an ash content of 11.77% and 13.53% middlings were obtained, and 21.61% gangue was removed in two successive separation stages with the probable errors of 0.05 and 0.07 g/cm3, respectively.

  8. Flame Propagation Through Concentration Gradient

    Institute of Scientific and Technical Information of China (English)

    JunyaIINO; MitsuakiTANABE; 等

    2000-01-01

    The experiment was carried out in homogeneous propane-air mixture and in several concentration gradient of mixture.Igniter is put on the upper side of the combustion chamber,In concentration gradient experiment.ixture was ignited from lean side.An experimental study was conducted in a combustion chamber.The combustion chamber has glass windows for optical measurements at any side.For the measurement of distribution of fuel concentration,infraed absorption method using 3.39μm He-Ne laser was used,and for the observation of proagating flams,Schlieren method was employed.As a measurment result of flame propagation velocity and flammable limit,for a mixture of an identical local equivalence ratio.flame propagation velocity in concentration gradient is faster than that in homogeneous mixture,and rich flammable limit in concentration gradient shows a tendency to be higher than that in homogeneous mixture.

  9. The Interaction of High-Speed Turbulence with Flames: Global Properties and Internal Flame Structure

    CERN Document Server

    Poludnenko, Alexei Y; 10.1016/j.combustflame.2009.11.018

    2011-01-01

    We study the dynamics and properties of a turbulent flame, formed in the presence of subsonic, high-speed, homogeneous, isotropic Kolmogorov-type turbulence in an unconfined system. Direct numerical simulations are performed with Athena-RFX, a massively parallel, fully compressible, high-order, dimensionally unsplit, reactive-flow code. A simplified reaction-diffusion model represents a stoichiometric H2-air mixture. The system being modeled represents turbulent combustion with the Damkohler number Da = 0.05 and with the turbulent velocity at the energy injection scale 30 times larger than the laminar flame speed. The simulations show that flame interaction with high-speed turbulence forms a steadily propagating turbulent flame with a flame brush width approximately twice the energy injection scale and a speed four times the laminar flame speed. A method for reconstructing the internal flame structure is described and used to show that the turbulent flame consists of tightly folded flamelets. The reaction zon...

  10. The Appilication of High-Density Electrical Method in Lingxin Coal Mine Goaf Detecting%高密度电法在灵新煤矿采空区探测中的应用

    Institute of Scientific and Technical Information of China (English)

    武书泉; 梅超; 李建武; 职荣军

    2015-01-01

    The high-density electrical method has been widely used in the detection of coal goaf. As the properties of goaf filling are different, it results that the performance characteristics in the data section of the high density electrical method are distinctive too. The paper mainly introduces the case that detected with the high-density electrical method in the aged coal goaf. Detection of the Linxin aged pita by using the Wenner device of high-density electrical method has achieved a good effect. According to the survey result ,work outside the section and the partial filled aged pita goaf showed in a high apparent resistivity anomaly , and the goaf is shown as the low apparent resistivity anomaly. It must be noted that a large number of construction waste on the ground and buildings being used have caused a great difficulties on the the grounded electrode and some other excution of electrical prospecting work. The test data that expressed in the dry sand of the Quaternary wind will take shape of a high resistivity layer on the shallow layer,form a high resistance shielding effect on the lower formation and cause the deep data of profile coming with a kind of illusion.%高密度电法已广泛应用于煤层采空区的探测中,采空区充填的性质不同造成其在高密度电法数据剖面中的表现特征也不一样.文章主要介绍运用高密度电法工作进行煤矿老窑采空区探测的案例.采用高密度电法中的温纳装置对灵新煤矿老窑采空区的探测,取得了很好的效果.探测结果表明,未采空和部分充填的老窑采空区表现为高视电阻率异常,而采空区则表现为低视电阻率异常.需注意的是在地面堆积的大量建筑垃圾及正在使用的建筑物给电法勘探工作的大线铺设、电极接地等施工带来了极大的困难.测试数据在第四系风积砂覆盖的干燥黄沙,会造成浅层形成一高阻率层,会对下部地层形成高阻屏蔽影响,造成剖面深部数据出现假象.

  11. LES of Sooting Flames

    Science.gov (United States)

    2006-12-01

    particles and the number density Nsi of the soot particles of size class i. The terms Rr, Cr and Sr are the moment rates that count for nucleation...Yk = Yk,inlet DQi,j,k,1 = −∆ td (1) (207) Where all the derivatives are calculated by forward differencing from the interior domain. 6.7.4 Subsonic Non...variables ~DQ is described as follows: DQi,j,k,1 = −∆ td (1) DQi,j,k,2 = −∆t (Ud(1) + ρd(3)) DQi,j,k,3 = −∆t (V d(1) + ρd(4)) DQi,j,k,4 = −∆t (Wd(1) + ρd(5

  12. Bounds for the propagation speed of combustion flames

    Energy Technology Data Exchange (ETDEWEB)

    Fort, Joaquim [Departament de FIsica, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia (Spain); Campos, Daniel [Grup de FIsica EstadIstica, Departament de FIsica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Gonzalez, Josep R [Grup de Mecanica de Fluids, Departament d' Enginyeria Mecanica, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia (Spain); Velayos, Joaquim [Grup de Mecanica de Fluids, Departament d' Enginyeria Mecanica, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia (Spain)

    2004-07-23

    We focus on a combustion model for premixed flames based on two coupled equations determining the spatial dynamics of temperature and fuel density. We rewrite these equations as a classical reaction-diffusion model, so that we can apply some known methods for the prediction of lower and upper bounds to the front speed. The predictions are compared to simulations, which show that our new bounds substantially improve those following from the linearization method, used in the previous work of Fort et al (2000 J. Phys. A: Math. Gen. 33 6953). Radiative losses lead to pulses rather than fronts. We find a bound for their speed which (in contrast to the linearization one) correctly predicts the order of magnitude of the flame speed.

  13. Heat and mass transfer in flames

    Science.gov (United States)

    Faeth, G. M.

    1986-01-01

    Heat- and mass-transfer processes in turbulent diffusion flames are discussed, considering turbulent mixing and the structure of single-phase flames, drop processes in spray flames, and nonluminous and luminous flame radiation. Interactions between turbulence and other phenomena are emphasized, concentrating on past work of the author and his associates. The conserved-scalar formalism, along with the laminar-flamelet approximation, is shown to provide reasonable estimates of the structure of gas flames, with modest levels of empiricism. Extending this approach to spray flames has highlighted the importance of drop/turbulence interactions; e.g., turbulent dispersion of drops, modification of turbulence by drops, etc. Stochastic methods being developed to treat these phenomena are yielding encouraging results.

  14. Subfilter Scale Combustion Modelling for Large Eddy Simulation of Turbulent Premixed Flames

    Science.gov (United States)

    Shahbazian, Nasim

    Large eddy simulation (LES) is a powerful computational tool for modelling turbulent combustion processes. However, for reactive flows, LES is still under significant development. In particular, for turbulent premixed flames, a considerable complication of LES is that the flame thickness is generally much smaller than the LES filter width such that the flame front and chemical reactions cannot be resolved on the grid. Accurate and robust subfilter-scale (SFS) models of the unresolved turbulence-chemistry interactions are therefore required and studies are needed to evaluate and improve them. In this thesis, a detailed comparison and evaluation of five different SFS models for turbulence- chemistry interactions in LES of premixed flames is presented. These approaches include both flamelet- and non-flamelet-based models, coupled with simple or tabulated chemistry. The mod- elling approaches considered herein are: algebraic- and transport-equation variants of the flame surface density (FSD) model, the presumed conditional moment (PCM) with flame prolongation of intrinsic low-dimensional manifold (FPI) tabulated chemistry, or PCM-FPI approach, evaluated with two different presumed probability density function (PDF) models; and conditional source-term estimation (CSE) approach. The predicted LES solutions are compared to the existing laboratory-scale experimental observation of Bunsen-type turbulent premixed methane-air flames, corresponding to lean and stoichiometric conditions lying from the upper limit of the flamelet regime to well within the thin reaction zones regime of the standard regimes diagram. Direct comparison of different SFS approaches allows investigation of stability and performance of the models, while the weaknesses and strengths of each approach are identified. Evaluation of algebraic and transported FSD models highlights the importance of non-equilibrium transport in turbulent premixed flames. The effect of the PDF type for the reaction progress

  15. Estimation of in situ resources, recoverable reserves and marketable reserves from a coal quality perspective

    Energy Technology Data Exchange (ETDEWEB)

    Leach, B.; Whitby, K.; Meyers, A. [A & B Mylec Pty. Ltd., Rockhampton, Qld. (Australia)

    2000-10-01

    The competitive nature of the coal industry currently has meant that attention to detail in estimating coal resources, and recoverable and marketable reserves is of greater importance now than probably at any other time in the history of the Australian coal industry. This paper describes the mechanisms applied in deriving the best possible resource and reserve estimates in evaulating a coal lease, largely from the coal quality perspective. It attempts to show one way of uniting the geological model of a coal deposit to quality aspects such as in situ density and tonnage and ultimately to the anticipated product coal tonnes. 2 refs., 3 figs., 4 tabs.

  16. Flame Suppression Agent, System and Uses

    Science.gov (United States)

    Parrish, Clyde F. (Inventor)

    2013-01-01

    Aqueous droplets encapsulated in a flame retardant polymer are useful in suppressing combustion. Upon exposure to a flame, the encapsulated aqueous droplets rupture and vaporize, removing heat and displacing oxygen to retard the combustion process. The polymer encapsulant, through decomposition, may further add free radicals to the combustion atmosphere, thereby further retarding the combustion process. The encapsulated aqueous droplets may be used as a replacement to halon, water mist and dry powder flame suppression systems.

  17. Queensland coal inventory

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-04-01

    Australia's black coal resources rank in the top five globally, around 50% of which are located in the sedimentary basins of Queensland. The Bowen Basin is the most prolific coal repository, hosting over 60% of the currently established resource inventory. Large volumes of thermal coal are present in the Surat and Galilee basins as well as small extensional and pull apart basins such as Blair Athol and Tarong. The article examines Queensland's coal industry from a government perspective. It first discusses the current coal market, then introduces the concept of inventory coal and explains the Australia Joint Ore Reserves Committee (JORC) code - a resource evaluation system. The stratigraphy of each of Queensland's coal basins is then discussed in sections headed Permian coals, Triassic coals, Jurassic and Cretaceous coals, and Tertiary coals. 3 figs.

  18. 高密度电法探测煤火的模拟及应用研究%Simulation of high-density electrical method in detecting coal fires and its application

    Institute of Scientific and Technical Information of China (English)

    邵振鲁; 王德明; 王雁鸣

    2013-01-01

    In this paper, the geo-electricity model of coal fires were established, and the forward modelings of Wenner α, dipole-dipole, Wenner-Schlumberger, pole-pole and pole-dipole were carried out by using the finite difference method. After adding noise interference into the forward data, the in-version was implemented to get the sectional drawing of apparent resistivity by using Gauss-Newton it-eration method. The inversion results show that all the burning center, burned cave and loose zone pre-sent abnormalities in the sectional drawings of apparent resistivity of the five array types, while Wenner-Schlumberger array has the best effect in distinguishing the burning center, and the Wennerαarray has the best effect in distinguishing the burned cave and loose zone. Moreover, the two array types mentioned above were applied to carry out high-density electrical detection in one fire zone, and the burning center, burned cave and loose zone were distinguished accurately. The research results provide theoretical basis and reference for the accurate detection of coal fires.%  通过建立煤火的地电模型,采用有限差分法对温纳等5种装置进行正演模拟,在对正演数据加入噪声干扰后,采用高斯-牛顿迭代法进行迭代求解反演。反演结果表明:火区燃烧中心、烧空区和冒落带在5种装置的视电阻率拟断面图上均反映出了异常;复合对称四极装置对火区燃烧中心的分辨效果最好,温纳装置对烧空区和冒落带的分辨效果最好。采用以上2种装置类型对某火区进行了高密度电法探测,准确的分辨出了该火区的燃烧中心、烧空区和冒落带。研究成果为煤田火灾的准确探测提供了相应的理论基础和参考。

  19. Comparative Analysis of Flame Characteristics of Castor Oil and ...

    African Journals Online (AJOL)

    Flame Retardants Used in Polyurethane Foam Systems. Polycarp .O. Ikeh ... such as ignition time, flame propagation rate, after glow, char rate, add-on and glow time. These properties .... hours before the flame test to ensure complete curing.

  20. Pole solutions for flame front propagation

    CERN Document Server

    Kupervasser, Oleg

    2015-01-01

    This book deals with solving mathematically the unsteady flame propagation equations. New original mathematical methods for solving complex non-linear equations and investigating their properties are presented. Pole solutions for flame front propagation are developed. Premixed flames and filtration combustion have remarkable properties: the complex nonlinear integro-differential equations for these problems have exact analytical solutions described by the motion of poles in a complex plane. Instead of complex equations, a finite set of ordinary differential equations is applied. These solutions help to investigate analytically and numerically properties of the flame front propagation equations.

  1. Determination of tellurium by hydride generation with in situ trapping flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Matusiewicz, H.; Krawczyk, M. [Politechn Poznanska, Poznan (Poland)

    2007-03-15

    The analytical performance of coupled hydride generation - integrated atom trap (HG-IAT) atomizer flame atomic absorption spectrometry (FAAS) system was evaluated for determination of Te in reference material (GBW 07302 Stream Sediment), coal fly ash and garlic. Tellurium, using formation of H{sub 2}Te vapors, is atomized in air-acetylene flame-heated IAT. A new design HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangernents (a water-cooled single silica tube, double-slotted quartz tube or an 'integrated trap') was investigated. An improvement in detection limit was achieved compared with using either of the above atom trapping techniques separately. The concentration detection limit, defined as 3 times the blank standard deviation (3{sigma}), was 0.9 ng mL{sup -1} for Te. For a 2 min in situ preconcentration time (sample volume of 2 mL), sensitivity enhancement compared to flame AAS, was 222 fold, using the hydride generation atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision, expressed as RSD, was 7.0% (n = 6) for Te. The accuracy of the method was verified using a certified reference material (GBW 07302 Stream Sediment) by aqueous standard calibration curves. The measured Te contents of the reference material was in agreement with the information value. The method was successfully applied to the determination of tellurium in coal fly ash and garlic.

  2. Impact of nongray multiphase radiation in pulverized coal combustion

    Science.gov (United States)

    Roy, Somesh; Wu, Bifen; Modest, Michael; Zhao, Xinyu

    2016-11-01

    Detailed modeling of radiation is important for accurate modeling of pulverized coal combustion. Because of high temperature and optical properties, radiative heat transfer from coal particles is often more dominant than convective heat transfer. In this work a multiphase photon Monte Carlo radiation solver is used to investigate and to quantify the effect of nongray radiation in a laboratory-scale pulverized coal flame. The nongray radiative properties of carrier phase (gas) is modeled using HITEMP database. Three major species - CO, CO2, and H2O - are treated as participating gases. Two optical models are used to evaluate radiative properties of coal particles: a formulation based on the large particle limit and a size-dependent correlation. Effect of scattering due to coal particle is also investigated using both isotropic scattering and anisotropic scattering using a Henyey-Greenstein function. Lastly, since the optical properties of ash is very different from that of coal, the effect of ash content on the radiative properties of coal particle is examined. This work used Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number ACI-1053575.

  3. Soot zone structure and sooting limit in diffusion flames: Comparison of counterflow and co-flow flames

    Energy Technology Data Exchange (ETDEWEB)

    Kang, K.T.; Hwang, J.Y.; Chung, S.H. [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering; Lee, W. [Dankook Univ., Seoul (Korea, Republic of). Dept. of Mechanical Engineering

    1997-04-01

    Soot zone structures of counterflow and co-flow diffusion flames have been studied experimentally using the soot extinction-scattering, polycyclic aromatic hydrocarbon fluorescence, and laser Doppler velocimetry measurements. The counterflow flame has been numerically modelled with detailed chemistry. Results show that two different categories of sooting flame structures can be classified depending on the relative transport of soot particles to flames. These are the soot formation-oxidation flame and the soot formation flame. The soot formation-oxidation flame characteristics are observed in counterflow flames when located on the fuel side and in normal co-flow flames. In this case, soot particles are transported toward the high temperature region or the flame and experience soot inception, coagulation-growth, and oxidation. The soot formation flame characteristics are observed in counterflow flames when located on the oxidizer side and in inverse co-flow flames. In this case, soot particles are transported away from the flame without experiencing oxidation and finally leak through the stagnation plane in counterflow flames or leave the flame in inverse co-flow flames. Sooting limit measurements in both flames also substantiate the two different sooting flame structures and their characteristics.

  4. A novel reutilization method for waste printed circuit boards as flame retardant and smoke suppressant for poly (vinyl chloride).

    Science.gov (United States)

    Xiu, Fu-Rong; Weng, Huiwei; Qi, Yingying; Yu, Gending; Zhang, Zhigang; Zhang, Fu-Shen

    2016-09-05

    In this study, a novel reutilization method for waste printed circuit boards (PCBs) as flame retardant and smoke suppressant for poly (vinyl chloride) (PVC) was successfully testified. A supercritical water oxidation (SCWO) process was applied to treat waste PCBs before they could be used as flame retardants of PVC. The results indicated that SCWO conditions had a significant effect on the flame retarding and smoke suppressing properties of waste PCBs for PVC. Cu2O, CuO, and SnO2 were the main active ingredients in waste PCBs-derived flame retardants. A conversion of Cu elements (Cu(0)→Cu(+)→Cu(2+)) during SCWO process with the increase of reaction temperature was found to be the key influence factor for the flame retarding properties of SCWO-treated PCBs. The experiment results also showed that there was a synergistic effect of flame retardancy between Cu(+) and Cu(2+). After the optimized SCWO treatment, SCWO-treated PCBs significantly improved the flame retardancy and smoke suppression of PVC. Limiting oxygen index (LOI) and char yield (CY) increased with increasing SCWO-treated PCBs content in PVC, while smoke density rating (SDR) and maximum smoke density (MSD) decreased markedly. The mechanical properties of PVC samples were influenced in different degree by adding different content SCWO-treated PCBs.

  5. Unsteady Diffusion Flames: Ignition, Travel, and Burnout (SUBCORE Project: Simplified Unsteady Burning of Contained Reactants)

    Science.gov (United States)

    Fendell, Francis; Rungaldier, Harald

    1999-01-01

    An experimental apparatus for the examination of a planar, virtually strain-rate-free diffusion flame in microgravity has been designed and fabricated. Such a diffusion flame is characterized by relatively large spatial scale and high symmetry (to facilitate probing), and by relatively long fluid-residence time (to facilitate investigation of rates associated with sooting phenomena). Within the squat rectangular apparatus, with impervious, noncatalytic isothermal walls of stainless steel, a thin metallic splitter plate subdivides the contents into half-volumes. One half-volume initially contains fuel vapor diluted with an inert gas, and the other, oxidizer diluted with another inert gas-so that the two domains have equal pressure, density, and temperature. As the separator is removed, by translation in its own plane, through a tightly fitting slit in one side wall, a line ignitor in the opposite side wall initiates a triple-flame propagation across the narrow layer of combustible mixture formed near midheight in the chamber. The planar diffusion flame so emplaced is quickly disrupted in earth gravity. In microgravity, the planar flame persists, and travels ultimately into the half-volume containing the stoichiometrically deficient reactant; the flame eventually becomes extinguished owing to reactant depletion and heat loss to the walls.

  6. Numerical simulations of the process of multiple shock-flame interactions

    Science.gov (United States)

    Jiang, Hua; Dong, Gang; chen, Xiao; Wu, Jin-Tao

    2016-08-01

    Based on a weighted essentially nonoscillatory scheme, the multiple interactions of a flame interface with an incident shock wave and its reshock waves are numerically simulated by solving the compressible reactive Navier-Stokes equations with a single-step Arrhenius chemical reaction. The two-dimensional sinusoidally perturbed premixed flames with different initial perturbed amplitudes are used to investigate the effect of the initial perturbation on the flame evolutions. The results show that the development of the flame interface is directly affected by the initial perturbed amplitudes before the passages of reshock waves, and the perturbation development is mainly controlled by the Richtmyer-Meshkov instability (RMI). After the successive impacts of multiple reshock waves, the chemical reaction accelerates the consumption of reactants and leads to a gradual disappearance of the initial perturbed information. The perturbation developments in frozen flows with the same initial interface as those in reactive flows are also demonstrated. Comparisons of results between the reactive and frozen flows show that a chemical reaction changes the perturbation pattern of the flame interface by decreasing the density gradient, thereby weakening the baroclinic torque in the flame mixing region, and therefore plays a dominant role after the passage of reshock waves.

  7. Interplay of Darrieus-Landau instability and weak turbulence in premixed flame propagation

    Science.gov (United States)

    Creta, Francesco; Lamioni, Rachele; Lapenna, Pasquale Eduardo; Troiani, Guido

    2016-11-01

    In this study we investigate, both numerically and experimentally, the interplay between the intrinsic Darrieus-Landau (DL) or hydrodynamic instability of a premixed flame and the moderately turbulent flow field in which the flame propagates. The objective is threefold: to establish, unambiguously, through a suitably defined marker, the presence or absence of DL-induced effects on the turbulent flame, to quantify the DL effects on the flame propagation and morphology and, finally, to asses whether such effects are mitigated or suppressed as the turbulence intensity is increased. The numerical simulations are based on a deficient reactant model which lends itself to a wealth of results from asymptotic theory, such as the determination of stability limits. The skewness of the flame curvature probability density function is identified as an unambiguous morphological marker for the presence or absence of DL effects in a turbulent environment. In addition, the turbulent propagation speed is shown to exhibit a distinct dual behavior whereby it is noticeably enhanced in the presence of DL instability while it is unchanged otherwise. Furthermore, increasing the turbulence intensity is found to be mitigating with respect to DL-induced effects such as the mentioned dual behavior which disappears at higher intensities. Experimental propane and/or air Bunsen flames are also investigated, utilizing two distinct diameters, respectively, above and below the estimated DL cutoff wavelength. Curvature skewness is still clearly observed to act as a marker for DL instability while the turbulent propagation speed is concurrently enhanced in the presence of the instability.

  8. Flame dynamics of a meso-scale heat recirculating combustor

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, V.; Gupta, A.K. [Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States)

    2010-12-15

    The dynamics of premixed propane-air flame in a meso-scale ceramic combustor has been examined here. The flame characteristics in the combustor were examined by measuring the acoustic emissions and preheat temperatures together with high-speed cinematography. For the small-scale combustor, the volume to surface area ratio is small and hence the walls have significant effect on the global flame structure, flame location and flame dynamics. In addition to the flame-wall thermal coupling there is a coupling between flame and acoustics in the case of confined flames. Flame-wall thermal interactions lead to low frequency flame fluctuations ({proportional_to}100 Hz) depending upon the thermal response of the wall. However, the flame-acoustic interactions can result in a wide range of flame fluctuations ranging from few hundred Hz to few kHz. Wall temperature distribution is one of the factors that control the amount of reactant preheating which in turn effects the location of flame stabilization. Acoustic emission signals and high-speed flame imaging confirmed that for the present case flame-acoustic interactions have more significant effect on flame dynamics. Based on the acoustic emissions, five different flame regimes have been identified; whistling/harmonic mode, rich instability mode, lean instability mode, silent mode and pulsating flame mode. (author)

  9. Applied coal petrology: the role of petrology in coal utilization

    Energy Technology Data Exchange (ETDEWEB)

    Isabel Suarez-Ruiz; John Crelling [Instituto Nacional del Carbon (INCAR-CSIC), Oviedo (Spain)

    2008-08-15

    This book is an integrated approach towards the applications of coal (organic) petrology and discusses the role of this science in the field of coal and coal-related topics. Contents are: Introduction 2. Basic factors controlling coal quality and technological behaviour of coal 3. Mining and benefication 4. Coal combustion 5. Coal gasification 6. Coal liquefaction 7. Coal carbonisation 8. Coal-derived carbons 9. Coal as a Petroleum source rock and reservoir rock 10. Environmental and health aspects 11. Other applications of coal petrology.

  10. Synthesis of mesoporous silica@Co-Al layered double hydroxide spheres: layer-by-layer method and their effects on the flame retardancy of epoxy resins.

    Science.gov (United States)

    Jiang, Shu-Dong; Bai, Zhi-Man; Tang, Gang; Song, Lei; Stec, Anna A; Hull, T Richard; Hu, Yuan; Hu, Wei-Zhao

    2014-08-27

    Hierarchical mesoporous silica@Co-Al layered double hydroxide (m-SiO2@Co-Al LDH) spheres were prepared through a layer-by-layer assembly process, in order to integrate their excellent physical and chemical functionalities. TEM results depicted that, due to the electrostatic potential difference between m-SiO2 and Co-Al LDH, the synthetic m-SiO2@Co-Al LDH hybrids exhibited that m-SiO2 spheres were packaged by the Co-Al LDH nanosheets. Subsequently, the m-SiO2@Co-Al LDH spheres were incorporated into epoxy resin (EP) to prepare specimens for investigation of their flame-retardant performance. Cone results indicated that m-SiO2@Co-Al LDH incorporated obviously improved fire retardant of EP. A plausible mechanism of fire retardant was hypothesized based on the analyses of thermal conductivity, char residues, and pyrolysis fragments. Labyrinth effect of m-SiO2 and formation of graphitized carbon char catalyzed by Co-Al LDH play pivotal roles in the flame retardance enhancement.

  11. 西门子高密度沉淀池在煤化工回用水的应用研究%Applied Research on Recycle Water of Coal Chemical Industry in SIEMENS High-density Sedimentation Tank

    Institute of Scientific and Technical Information of China (English)

    李孝洪

    2012-01-01

      某煤制烯烃项目回用水装置采用德国西门子公司高密度沉淀池专利技术,该装置自2010年5月底运行至今,曾多次出现影响高密度沉淀池正常运行的严重问题,具体表现为沉淀区产生高浓度黏泥无法正常排出和絮凝区产生积泥破坏絮凝区水动力平衡,最终导致高密度沉淀池出水不合格。为了解决这些难题,经过不断摸索,通过控制絮凝区和沉淀区较低的5min沉降比与定时排泥相结合和改变絮凝区搅拌器的转动方向的运行方式,系统运行近3个月后未出现上述问题,表明采取的措施有一定效果。%  The high-density sedimentation tank patent technology, belonging to German Siemens Company, is adopted by water reuse device of a coal-to-olefin project. Since the end of May 2010, the device has appeared serious problems that effect normal operation of high-density sedimentation tank. Settling zone produced high concentration sludge that can not be discharged properly and flocculation zone produced mud that damage its water dynamic balance, eventually it leads to high density tank water unqualified. In order to solve these problems, we adopt a new mode of operation through continuous exploration:1. Control settlement ratio (5 minutes)of flocculation area and sedimentation zone combining with timing dredge;2. Change the rotation direction of agitator in flocculation zone. The system has not appeared afore-mentioned problems after running for nearly three months, showing that the measures adopted have certain effect.

  12. Unsteady planar diffusion flames: Ignition, travel, burnout

    Science.gov (United States)

    Fendell, F.; Wu, F.

    1995-01-01

    In microgravity, a thin planar diffusion flame is created and thenceforth travels so that the flame is situated at all times at an interface at which the hydrogen and oxygen meet in stoichiometric proportion. If the initial amount of hydrogen is deficient relative to the initial amount of oxygen, then the planar flame will travel further and further into the half volume initially containing hydrogen, until the hydrogen is (virtually) fully depleted. Of course, when the amount of residual hydrogen becomes small, the diffusion flame is neither vigorous nor thin; in practice, the flame is extinguished before the hydrogen is fully depleted, owing to the finite rate of the actual chemical-kinetic mechanism. The rate of travel of the hydrogen-air diffusion flame is much slower than the rate of laminar flame propagation through a hydrogen-air mixture. This slow travel facilitates diagnostic detection of the flame position as a function of time, but the slow travel also means that the time to burnout (extinction) probably far exceeds the testing time (typically, a few seconds) available in earth-sited facilities for microgravity-environment experiments. We undertake an analysis to predict (1) the position and temperature of the diffusion flame as a function of time, (2) the time at which extinction of the diffusion flame occurs, and (3) the thickness of quench layers formed on side walls (i.e., on lateral boundaries, with normal vectors parallel to the diffusion-flame plane), and whether, prior to extinction, water vapor formed by burning will condense on these cold walls.

  13. Tulip flames: changes in shape of premixed flames propagating in closed tubes

    Science.gov (United States)

    Dunn-Rankin, D.; Sawyer, R. F.

    The experimental results that are the subject of this communication provide high-speed schlieren images of the closed-tube flame shape that has come to be known as the tulip flame. The schlieren images, along with in-chamber pressure records, help demonstrate the effects of chamber length, equivalence ratio, and igniter geometry on formation of the tulip flame. The pressure/time records show distinct features which correlate with flame shape changes during the transition to tulip. The measurements indicate that the basic tulip flame formation is a robust phenomenon that depends on little except the overall geometry of the combustion vessel.

  14. SOOT PARTICLES ANALYSIS IN LAMINAR PREMIXED PROPANE/OXYGEN (C3H8/O2) FLAMES USING PUBLISHED MEASUREMENT DATA

    Institute of Scientific and Technical Information of China (English)

    Jinling Li; Suyuan Yu

    2003-01-01

    A laminar premixed Propane/Air flame with a fuel equivalence ratio of 2.1 was employed for analysis of soot particles. Zeroth-order Iognormal distributions (ZOLD) were used in the analysis of experimental distribution phenomena at different residence times during soot formation in the flame. Rayleigh's theory and Mie's scattering theory were combined with agglomerate analysis using scattering and extinction data to determine the following soot characteristics: agglomerate parameters, volumetric fractions, mass flow rates and surface growth rate. Soot density measurements were carried out to determine density variations at different stages of growth. The measured results show that metric fraction and mass flow rate indicate that the surface growth rate of soot particles exceeds the oxidation rates in the flame studied. The data obtained in this work would be used to study soot oxidation rate under flaming condition.

  15. Large Eddy Simulation Of Gravitational Effects In Transitional And Turbulent Gas-Jet Diffusion Flames

    Science.gov (United States)

    Jaberi, Farhad A.; Givi, Peyman

    2003-01-01

    The influence of gravity on the spatial and the compositional structures of transitional and turbulent hydrocarbon diffusion flames are studies via large eddy simulation (LES) and direct numerical simulation (DNS) of round and planar jets. The subgrid-scale (SGS) closures in LES are based on the filtered mass density function (FMDF) methodology. The FMDF represents the joint probability density function (PDF) of the SGS scalars, and is obtained by solving its transport equation. The fundamental advantage of LES/FMDF is that it accounts for the effects of chemical reaction and buoyancy exactly. The methodology is employed for capturing some of the fundamental influences of gravity in equilibrium flames via realistic chemical kinetic schemes. Some preliminary investigation of the gravity effects in non-equilibrium flames is also conducted, but with idealized chemical kinetics models.

  16. Testing of a Hydrogen Diffusion Flame Array Injector at Gas Turbine Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, Nathan T.; Sidwell, Todd G.; Strakey, Peter A.

    2013-07-03

    High-hydrogen gas turbines enable integration of carbon sequestration into coal-gasifying power plants, though NO{sub x} emissions are often high. This work explores nitrogen dilution of hydrogen diffusion flames to reduce thermal NO{sub x} emissions and avoid problems with premixing hydrogen at gas turbine pressures and temperatures. The burner design includes an array of high-velocity coaxial fuel and air injectors, which balances stability and ignition performance, combustor pressure drop, and flame residence time. Testing of this array injector at representative gas turbine conditions (16 atm and 1750 K firing temperature) yields 4.4 ppmv NO{sub x} at 15% O{sub 2} equivalent. NO{sub x} emissions are proportional to flame residence times, though these deviate from expected scaling due to active combustor cooling and merged flame behavior. The results demonstrate that nitrogen dilution in combination with high velocities can provide low NO{sub x} hydrogen combustion at gas turbine conditions, with significant potential for further NO{sub x} reductions via suggested design changes.

  17. Testing of a Hydrogen Diffusion Flame Array Injector at Gas Turbine Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, Nathan T.; Sidwell, Todd G.; Strakey, Peter A.

    2013-07-03

    High-hydrogen gas turbines enable integration of carbon sequestration into coal-gasifying power plants, though NO{sub x} emissions are often high. This work explores nitrogen dilution of hydrogen diffusion flames to reduce thermal NO{sub x} emissions and avoid problems with premixing hydrogen at gas turbine pressures and temperatures. The burner design includes an array of high-velocity coaxial fuel and air injectors, which balances stability and ignition performance, combustor pressure drop, and flame residence time. Testing of this array injector at representative gas turbine conditions (16 atm and 1750 K firing temperature) yields 4.4 ppmv NO{sub x} at 15% O{sub 2} equivalent. NO{sub x} emissions are proportional to flame residence times, though these deviate from expected scaling due to active combustor cooling and merged flame behavior. The results demonstrate that nitrogen dilution in combination with high velocities can provide low NO{sub x} hydrogen combustion at gas turbine conditions, with significant potential for further NO{sub x} reductions via suggested design changes.

  18. Impact of flame-wall interaction on premixed flame dynamics and transfer function characteristics

    KAUST Repository

    Kedia, K.S.

    2011-01-01

    In this paper, we numerically investigate the response of a perforated-plate stabilized laminar methane-air premixed flame to imposed inlet velocity perturbations. A flame model using detailed chemical kinetics mechanism is applied and heat exchange between the burner plate and the gas mixture is incorporated. Linear transfer functions, for low mean inlet velocity oscillations, are analyzed for different equivalence ratio, mean inlet velocity, plate thermal conductivity and distance between adjacent holes. The oscillations of the heat exchange rate at the top of the burner surface plays a critical role in driving the growth of the perturbations over a wide range of conditions, including resonance. The flame response to the perturbations at its base takes the form of consumption speed oscillations in this region. Flame stand-off distance increases/decreases when the flame-wall interaction strengthens/weakens, impacting the overall dynamics of the heat release. The convective lag between the perturbations and the flame base response govern the phase of heat release rate oscillations. There is an additional convective lag between the perturbations at the flame base and the flame tip which has a weaker impact on the heat release rate oscillations. At higher frequencies, the flame-wall interaction is weaker and the heat release oscillations are driven by the flame area oscillations. The response of the flame to higher amplitude oscillations are used to gain further insight into the mechanisms. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

  19. Numerical modeling of turbulent combustion and flame spread

    Energy Technology Data Exchange (ETDEWEB)

    Yan Zhenghua

    1999-01-01

    Theoretical models have been developed to address several important aspects of numerical modeling of turbulent combustion and flame spread. The developed models include a pyrolysis model for charring and non-charring solid materials, a fast narrow band radiation property evaluation model (FASTNB) and a turbulence model for buoyant flow and flame. In the pyrolysis model, a completely new algorithm has been proposed, where a moving dual mesh concept was developed and implemented. With this new concept, it provides proper spatial resolution for both temperature and density and automatically considers the regression of the surface of the non-charring solid material during its pyrolysis. It is simple, very efficient and applicable to both charring and non-charring materials. FASTNB speeds up significantly the evaluation of narrow band spectral radiation properties and thus provides a potential of applying narrow band model in numerical simulations of practical turbulent combustion. The turbulence model was developed to improve the consideration of buoyancy effect on turbulence and turbulent transport. It was found to be simple, promising and numerically stable. It has been tested against both plane and axisymmetric thermal plumes and an axisymmetric buoyant diffusion flame. When compared with the widely used standard buoyancy-modified {kappa} - {epsilon} model, it gives significant improvement on numerical results. These developed models have been fully incorporated into CFD (Computational Fluid Dynamics) code and coupled with other CFD sub-models, including the DT (Discrete Transfer) radiation model, EDC (Eddy Dissipation Concept) combustion model, flamelet combustion model, various soot models and transpired wall function. Comprehensive numerical simulations have been carried out to study soot formation and oxidation in turbulent buoyant diffusion flames, flame heat transfer and flame spread in fires. The gas temperature and velocity, soot volume fraction, wall

  20. Numerical Study on Laminar Burning Velocity and Flame Stability of Premixed Methane/Ethylene/Air Flames

    Institute of Scientific and Technical Information of China (English)

    陈珊珊; 蒋勇; 邱榕; 安江涛

    2012-01-01

    A numerical study on premixed methane/ethylene/air flames with various ethylene fractions and equivalence ratios was conducted at room temperature and atmospheric pressure. The effects of ethylene addition on laminar burning velocity, flame structure and flame stability under the condition of lean burning were investigated. The results show that the laminar burning velocity increases with ethylene fraction, especially at a large equivalence ratio. More ethylene addition gives rise to higher concentrations of H, O and OH radicals in the flame, which significantly promotes chemical reactions, and a linear correlation exists between the laminar burning velocity and the maximum H + OH concentration in the reaction zone. With the increase of ethylene fraction, the adiabatic flame temperature is raised, while the inner layer temperature becomes lower, contributing to the enhancement of combustion. Markstein length and Markstein number, representative of the flame stability, increase as more ethylene is added, indicating the tendency of flame stability to improve with ethylene addition.

  1. On the transition from a highly turbulent curved flame into a tulip flame

    Energy Technology Data Exchange (ETDEWEB)

    Kratzel, T.; Pantow, E.; Fischer, M. [German Aerospace Research Establishment, Stuttgart (Germany). Institute of Technical Thermodynamics

    1998-12-31

    Experimental and numerical investigations of premixed flame propagation behaviour associated with vortex interactions due to planar pressure waves crossing a curved flame front have been carried out. The resulting ``tulip flame`` formation in such a closed tube has been studied by Schlieren visualization. The ``tulip flame`` phenomenon was observed only closed tubes, while cellular flame fronts appeared in half-open tubes. A physical model has been developed and implemented in a discrete vortex method combined with a flame tracking algorithm. The numerical method has been applied to model and understand the processes that cause the flame to change from a curved to a tulip shape. The results of the simulation are in good agreement with the experimental observations. (author)

  2. HIGH PRESSURE COAL COMBUSTON KINETICS PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Stefano Orsino

    2005-03-30

    As part of the U.S. Department of Energy (DoE) initiative to improve the efficiency of coal-fired power plants and reduce the pollution generated by these facilities, DOE has funded the High-Pressure Coal Combustion Kinetics (HPCCK) Projects. A series of laboratory experiments were conducted on selected pulverized coals at elevated pressures with the specific goals to provide new data for pressurized coal combustion that will help extend to high pressure and validate models for burnout, pollutant formation, and generate samples of solid combustion products for analyses to fill crucial gaps in knowledge of char morphology and fly ash formation. Two series of high-pressure coal combustion experiments were performed using SRI's pressurized radiant coal flow reactor. The first series of tests characterized the near burner flame zone (NBFZ). Three coals were tested, two high volatile bituminous (Pittsburgh No.8 and Illinois No.6), and one sub-bituminous (Powder River Basin), at pressures of 1, 2, and 3 MPa (10, 20, and 30 atm). The second series of experiments, which covered high-pressure burnout (HPBO) conditions, utilized a range of substantially longer combustion residence times to produce char burnout levels from 50% to 100%. The same three coals were tested at 1, 2, and 3 MPa, as well as at 0.2 MPa. Tests were also conducted on Pittsburgh No.8 coal in CO2 entrainment gas at 0.2, 1, and 2 MPa to begin establishing a database of experiments relevant to carbon sequestration techniques. The HPBO test series included use of an impactor-type particle sampler to measure the particle size distribution of fly ash produced under complete burnout conditions. The collected data have been interpreted with the help of CFD and detailed kinetics simulation to extend and validate devolatilization, char combustion and pollutant model at elevated pressure. A global NOX production sub-model has been proposed. The submodel reproduces the performance of the detailed chemical

  3. Assessing coal burnout

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, A. [Pacific Power, Sydney, NSW (Australia)

    1999-11-01

    Recent research has allowed a quantitative description of the basic process of burnout for pulverized coals to be made. The Cooperative Research Centre for Black Coal Utilization has built on this work to develop a coal combustion model which will allow plant engineers and coal company representatives to assess their coals for combustion performance. The paper describes the model and its validation and outlines how it is run. 2 figs.

  4. Colombian coal focus

    Energy Technology Data Exchange (ETDEWEB)

    Warden-Fernandez, J.; Rodriguez, L.E. [University of Dundee, Dundee (United Kingdom)

    2003-03-01

    The paper reviews the development of Colombia's coal industry over recent years. Colombia has recently modernised its mining code, Law 685 of 2001 concerning mineral rights and including the concept of sustainable development. The article discusses the legislation, analyses trends in Columbia's income from the coal and mineral industries (nickel, gold, emerald), and briefly discusses coal reserves, mining projects, coal exports and markets for Colombian coal. 7 refs., 7 figs., 4 tabs.

  5. Coal markets in transition

    Energy Technology Data Exchange (ETDEWEB)

    Romer, R.

    1990-01-01

    Describes Colorado's coal industry, and the implementation of a nine point mining plan announced in 1988. This plan includes an environmental regulatory review, coal royalty reform, production and marketing incentives, clean coal and clean air issues, and promotion of the coal industry. Other issues to be addressed are abandoned mine reclamation, abandoned mine safety and land reclamation after surface mining. International markets for Colorado coal are also discussed.

  6. Coal combustion products

    Science.gov (United States)

    Kalyoncu, R.S.; Olson, D.W.

    2001-01-01

    Coal-burning powerplants, which supply more than half of U.S. electricity, also generate coal combustion products, which can be both a resource and a disposal problem. The U.S. Geological Survey collaborates with the American Coal Ash Association in preparing its annual report on coal combustion products. This Fact Sheet answers questions about present and potential uses of coal combustion products.

  7. Physical and Chemical Processing in Flames

    Science.gov (United States)

    2013-08-12

    than the classical Troe formula, and the development of a Chemical Explosive Mode Analysis ( CEMA ) computation algorithm that allows on-the-fly...6-311++G(d,p) method. 3. Flame Stabilization and Chemical Explosive Mode Analysis ( CEMA ) Flame stabilization is essential in the understanding of

  8. Development of PIV for Microgravity Diffusion Flames

    Science.gov (United States)

    Greenberg, Paul S.; Wernet, Mark P.; Yanis, William; Urban, David L.; Sunderland, Peter B.

    2003-01-01

    Results are presented from the application of Particle Image Velocimetry(PIV) to the overfire region of a laminar gas jet diffusion flame in normal gravity. A methane flame burning in air at 0.98 bar was considered. The apparatus demonstrated here is packaged in a drop rig designed for use in the 2.2 second drop tower.

  9. Chemical processes in the HNF flame

    NARCIS (Netherlands)

    Ermolin, N.E.; Zarko, V.E.; Keizers, H.L.J.

    2006-01-01

    Results of modeling the HNF flame structure are presented. From an analysis of literature data on the thermal decomposition and combustion of HNF, it is concluded that the dissociative vaporization of HNF proceeds via the route HNFliq → (N2H4)g + (HC(NO 2)3)g. The flame structure is modeled using a

  10. Flaming in CMC: Prometheus' Fire or Inferno's?

    Science.gov (United States)

    Abrams, Zsuzsanna Ittzes

    2003-01-01

    Reports on a descriptive study with 75 intermediate college learners of German participating in two sessions of synchronous computer mediated communication during the course of a semester that investigated students' flaming behavior--aggressive interpersonal language and rude behavior. Shows that not only is flaming a very infrequent occurrence,…

  11. Flame retardant cotton barrier nonwovens for mattresses

    Science.gov (United States)

    According to regulation CPSC 16 CFR 1633, every new residential mattress sold in the United States since July 2007 must resist ignition by open flame. An environmentally benign “green”, inexpensive way to meet this regulation is to use a low-cost flame retardant (FR) barrier fabric. In this study, a...

  12. Flame retardant cotton based highloft nonwovens

    Science.gov (United States)

    Flame retardancy has been a serious bottleneck to develop cotton blended very high specific volume bulky High loft fabrics. Alternately, newer approach to produce flame retardant cotton blended High loft fabrics must be employed that retain soft feel characteristics desirable of furnishings. Hence, ...

  13. Flaming in CMC: Prometheus' Fire or Inferno's?

    Science.gov (United States)

    Abrams, Zsuzsanna Ittzes

    2003-01-01

    Reports on a descriptive study with 75 intermediate college learners of German participating in two sessions of synchronous computer mediated communication during the course of a semester that investigated students' flaming behavior--aggressive interpersonal language and rude behavior. Shows that not only is flaming a very infrequent occurrence,…

  14. Physical and Chemical Processes in Turbulent Flames

    Science.gov (United States)

    2015-06-23

    DISTRIBUTION A: Distribution approved for public release. AF Office Of Scientific Research (AFOSR)/ RTE Arlington, Virginia 22203 Air Force Research...two-year subject program, conducted through tight coupling between experiment, theory and computation, and reported in high impact journal articles ...The thrust for this program constitutes of three major areas of turbulent combustion: (1) Flame surface statistics , (2) Flame-turbulence interaction

  15. Simulations of flame generated particles

    KAUST Repository

    Patterson, Robert

    2016-01-05

    The nonlinear structure of the equations describing the evolution of a population of coagulating particles in a flame make the use of stochastic particle methods attractive for numerical purposes. I will present an analysis of the stochastic fluctuations inherent in these numerical methods leading to an efficient sampling technique for steady-state problems. I will also give some examples where stochastic particle methods have been used to explore the effect of uncertain parameters in soot formation models. In conclusion I will try to indicate some of the issues in optimising these methods for the study of uncertain model parameters.

  16. Inertial particles in a turbulent premixed Bunsen flame

    Energy Technology Data Exchange (ETDEWEB)

    Battista, F.; Picano, F.; Casciola, C.M. [Sapienza Univ., Rome (Italy). Dipt. di Meccanica e Aeronautica; Troiani, G. [ENEA C.R. Casaccia, Rome (Italy)

    2012-07-01

    Many fields of engineering and physics are characterized by reacting flows seeded with particles of different inertia and dimensions, e.g. solid-propellant rockets, reciprocating engines where carbon particles form due to combustion, vulcano eruptions. Particles are also used as velocity transducers in Particle Image Velocimetry (PIV) of turbulent flames. The effects of combustion on inertial particle dynamics is still poorly understood, despite its relevance for its effects on particle collisions and coalescence, phenomena which have a large influence in soot formation and growth. As a matter of fact, the flame front induces abrupt accelerations of the fluid in a very thin region which particles follow with different lags depending on their inertia. This phenomenon has a large impact on the particle spatial arrangement. The issuing clustering is here analyzed by a DNS of Bunsen turbulent flame coupled with particle Lagrangian tracking with the aim of evaluating the effect of inertia on particle spatial localization in combustion applications. The Eulerian algorith is based on Low-Mach number expansion of Navier-Stokes equations that allow arbitrary density variations neglecting acoustics waves. (orig.)

  17. Coal data: A reference

    Energy Technology Data Exchange (ETDEWEB)

    1995-02-01

    This report, Coal Data: A Reference, summarizes basic information on the mining and use of coal, an important source of energy in the US. This report is written for a general audience. The goal is to cover basic material and strike a reasonable compromise between overly generalized statements and detailed analyses. The section ``Supplemental Figures and Tables`` contains statistics, graphs, maps, and other illustrations that show trends, patterns, geographic locations, and similar coal-related information. The section ``Coal Terminology and Related Information`` provides additional information about terms mentioned in the text and introduces some new terms. The last edition of Coal Data: A Reference was published in 1991. The present edition contains updated data as well as expanded reviews and additional information. Added to the text are discussions of coal quality, coal prices, unions, and strikes. The appendix has been expanded to provide statistics on a variety of additional topics, such as: trends in coal production and royalties from Federal and Indian coal leases, hours worked and earnings for coal mine employment, railroad coal shipments and revenues, waterborne coal traffic, coal export loading terminals, utility coal combustion byproducts, and trace elements in coal. The information in this report has been gleaned mainly from the sources in the bibliography. The reader interested in going beyond the scope of this report should consult these sources. The statistics are largely from reports published by the Energy Information Administration.

  18. Enhanced Combustion Low NOx Pulverized Coal Burner

    Energy Technology Data Exchange (ETDEWEB)

    David Towle; Richard Donais; Todd Hellewell; Robert Lewis; Robert Schrecengost

    2007-06-30

    economic evaluation and commercial application. During the project performance period, Alstom performed computational fluid dynamics (CFD) modeling and large pilot scale combustion testing in its Industrial Scale Burner Facility (ISBF) at its U.S. Power Plant Laboratories facility in Windsor, Connecticut in support of these objectives. The NOx reduction approach was to optimize near-field combustion to ensure that minimum NOx emissions are achieved with minimal impact on unburned carbon in ash, slagging and fouling, corrosion, and flame stability/turn-down. Several iterations of CFD and combustion testing on a Midwest coal led to an optimized design, which was extensively combustion tested on a range of coals. The data from these tests were then used to validate system costs and benefits versus SCR. Three coals were evaluated during the bench-scale and large pilot-scale testing tasks. The three coals ranged from a very reactive subbituminous coal to a moderately reactive Western bituminous coal to a much less reactive Midwest bituminous coal. Bench-scale testing was comprised of standard ASTM properties evaluation, plus more detailed characterization of fuel properties through drop tube furnace testing and thermogravimetric analysis. Bench-scale characterization of the three test coals showed that both NOx emissions and combustion performance are a strong function of coal properties. The more reactive coals evolved more of their fuel bound nitrogen in the substoichiometric main burner zone than less reactive coal, resulting in the potential for lower NOx emissions. From a combustion point of view, the more reactive coals also showed lower carbon in ash and CO values than the less reactive coal at any given main burner zone stoichiometry. According to bench-scale results, the subbituminous coal was found to be the most amenable to both low NOx, and acceptably low combustibles in the flue gas, in an air staged low NOx system. The Midwest bituminous coal, by contrast, was

  19. Edge Diffusion Flame Propagation and Stabilization Studied

    Science.gov (United States)

    Takahashi, Fumiaki; Katta, Viswanath R.

    2004-01-01

    In most practical combustion systems or fires, fuel and air are initially unmixed, thus forming diffusion flames. As a result of flame-surface interactions, the diffusion flame often forms an edge, which may attach to burner walls, spread over condensed fuel surfaces, jump to another location through the fuel-air mixture formed, or extinguish by destabilization (blowoff). Flame holding in combustors is necessary to achieve design performance and safe operation of the system. Fires aboard spacecraft behave differently from those on Earth because of the absence of buoyancy in microgravity. This ongoing in-house flame-stability research at the NASA Glenn Research Center is important in spacecraft fire safety and Earth-bound combustion systems.

  20. Interaction Between Flames and Electric Fields Studied

    Science.gov (United States)

    Yuan, Zeng-Guang; Hegde, Uday

    2003-01-01

    The interaction between flames and electric fields has long been an interesting research subject that has theoretical importance as well as practical significance. Many of the reactions in a flame follow an ionic pathway: that is, positive and negative ions are formed during the intermediate steps of the reaction. When an external electric field is applied, the ions move according to the electric force (the Coulomb force) exerted on them. The motion of the ions modifies the chemistry because the reacting species are altered, it changes the velocity field of the flame, and it alters the electric field distribution. As a result, the flame will change its shape and location to meet all thermal, chemical, and electrical constraints. In normal gravity, the strong buoyant effect often makes the flame multidimensional and, thus, hinders the detailed study of the problem.

  1. Free radical reaction characteristics of coal low-temperature oxidation and its inhibition method.

    Science.gov (United States)

    Li, Zenghua; Kong, Biao; Wei, Aizhu; Yang, Yongliang; Zhou, Yinbo; Zhang, Lanzhun

    2016-12-01

    Study on the mechanism of coal spontaneous combustion is significant for controlling fire disasters due to coal spontaneous combustion. The free radical reactions can explain the chemical process of coal at low-temperature oxidation. Electron spin resonance (ESR) spectroscopy was used to measure the change rules of the different sorts and different granularity of coal directly; ESR spectroscopy chart of free radicals following the changes of temperatures was compared by the coal samples applying air and blowing nitrogen, original coal samples, dry coal samples, and demineralized coal samples. The fragmentation process was the key factor of producing and initiating free radical reactions. Oxygen, moisture, and mineral accelerated the free radical reactions. Combination of the free radical reaction mechanism, the mechanical fragmentation leaded to the elevated CO concentration, fracturing of coal pillar was more prone to spontaneous combustion, and spontaneous combustion in goaf accounted for a large proportion of the fire in the mine were explained. The method of added diphenylamine can inhibit the self-oxidation of coal effectively, the action mechanism of diphenylamine was analyzed by free radical chain reaction, and this research can offer new method for the development of new flame retardant.

  2. Cool Sooting Flames of Hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    Z.A. MANSUROV

    2001-01-01

    This paper presents the study of polycyclic aromatic hydrocarbons (PAH) and paramagnetism of soot particles sampled from cool sooting flames of methane and propane in a separately-heated two-sectional reactor under atmospheric pressure at the reactor temperatures of 670-1170 K. The temperature profiles of the flames were studied. The sampling was carried out with a quartz sampler and the samples were frozen with liquid nitrogen. A number of polyaromatic hydrocarbons such as pyrene, fluoranthene, coronene, anthanthrene, 1,12-benzperylene,were identified by spectroscopic methods in the extract of soot. The processes of soot formation at methaneoxygen mixture combustion in the electric field with applied potential changed from 0 to 2,2 kV at different polarity of electrodes have been investigated. It has been stated that at the electrical field application, an increase in soot particle sizes and soot yield occurs; besides, at the application of the field, speeding up the positively charged particles, the interplanar distance decreases. On the basis of investigation of soot particles paramagnetism, it was shown that initially soot particles have high carcinogetic activity and pollute the environment owing to a rapid decrease of the number of these radical centers. The reduction of the radical concentration is connected with radical recombination on soot.

  3. Comparative study on direct burning of oil shale and coal

    Science.gov (United States)

    Hammad, Ahmad; Al Asfar, Jamil

    2017-07-01

    A comparative study of the direct burning processes of oil shale and coal in a circulating fluidized bed (CFB) was done in this study using ANSYS Fluent software to solve numerically the governing equations of continuity, momentum, energy and mass diffusion using finite volume method. The model was built based on an existing experimental combustion burner unit. The model was validated by comparing the theoretical results of oil shale with proved experimental results from the combustion unit. It was found that the temperature contours of the combustion process showed that the adiabatic flame temperature was 1080 K for oil shale compared with 2260 K for coal, while the obtained experimental results of temperatures at various locations of burner during the direct burning of oil shale showed that the maximum temperature reached 962 K for oil shale. These results were used in economic and environmental analysis which show that oil shale may be used as alternative fuel for coal in cement industry in Jordan.

  4. Experiment and Simulation of Autoignition in Jet Flames and its Relevance to Flame Stabilization and Structure

    KAUST Repository

    Al-Noman, Saeed M.

    2016-06-01

    Autoignition characteristics of pre-vaporized iso-octane, primary reference fuels, gasolines, and dimethyl ether (DME) have been investigated experimentally in a coflow with elevated temperature of air. With the coflow air at relatively low initial temperatures below autoignition temperature Tauto, an external ignition source was required to stabilize the flame. Non-autoignited lifted flames had tribrachial edge structures and their liftoff heights correlated well with the jet velocity scaled by the stoichiometric laminar burning velocity, indicating the importance of the edge propagation speed on flame stabilization balanced with local flow velocity. At high initial temperatures over Tauto, the autoignited flames were stabilized without requiring an external ignition source. The autoignited lifted flames exhibited either tribrachial edge structures or Mild combustion behaviors depending on the level of fuel dilution. For the iso-octane and n-heptane fuels, two distinct transition behaviors were observed in the autoignition regime from a nozzle-attached flame to a lifted tribrachial-edge flame and then a sudden transition to lifted Mild combustion as the jet velocity increased at a certain fuel dilution level. The liftoff data of the autoignited flames with tribrachial edges were analyzed based on calculated ignition delay times for the pre-vaporized fuels. Analysis of the experimental data suggested that ignition delay time may be much less sensitive to initial temperature under atmospheric pressure conditions as compared with predictions. For the gasoline fuels for advanced combustion engines (FACEs), and primary reference fuels (PRFs), autoignited liftoff data were correlated with Research Octane Number and Cetane Number. For the DME fuel, planar laser-induced fluorescence (PLIF) of formaldehyde (CH2O) and CH* chemiluminescence were visualized qualitatively. In the autoignition regime for both tribrachial structure and mild combustion, formaldehyde were found

  5. Flame Structure and Emissions of Strongly-Pulsed Turbulent Diffusion Flames with Swirl

    Science.gov (United States)

    Liao, Ying-Hao

    This work studies the turbulent flame structure, the reaction-zone structure and the exhaust emissions of strongly-pulsed, non-premixed flames with co-flow swirl. The fuel injection is controlled by strongly-pulsing the fuel flow by a fast-response solenoid valve such that the fuel flow is completely shut off between pulses. This control strategy allows the fuel injection to be controlled over a wide range of operating conditions, allowing the flame structure to range from isolated fully-modulated puffs to interacting puffs to steady flames. The swirl level is controlled by varying the ratio of the volumetric flow rate of the tangential air to that of the axial air. For strongly-pulsed flames, both with and without swirl, the flame geometry is strongly impacted by the injection time. Flames appear to exhibit compact, puff-like structures for short injection times, while elongated flames, similar in behaviors to steady flames, occur for long injection times. The flames with swirl are found to be shorter for the same fuel injection conditions. The separation/interaction level between flame puffs in these flames is essentially governed by the jet-off time. The separation between flame puffs decreases as swirl is imposed, consistent with the decrease in flame puff celerity due to swirl. The decreased flame length and flame puff celerity are consistent with an increased rate of air entrainment due to swirl. The highest levels of CO emissions are generally found for compact, isolated flame puffs, consistent with the rapid quenching due to rapid dilution with excess air. The imposition of swirl generally results in a decrease in CO levels, suggesting more rapid and complete fuel/air mixing by imposing swirl in the co-flow stream. The levels of NO emissions for most cases are generally below the steady-flame value. The NO levels become comparable to the steady-flame value for sufficiently short jet-off time. The swirled co-flow air can, in some cases, increase the NO

  6. Prediction of the burnout behaviour of chars derived from coal-biomass blends

    Energy Technology Data Exchange (ETDEWEB)

    Tao Wu; Mei Gong; Edward Lester [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering

    2007-07-01

    Nowadays, biomass has been considered an alternative fuel to coal and is being used in power plants to replace part of coal used. This study is to investigate the potential of burning biomass with coal and its impacts on burnout levels. Daw Mill coal was selected for burnout modelling together with three biomasses, Cereal, PKE and Olive Cake. Chars were prepared (75-106 micron) and characterised using image analysis methods as in input data into the char burnout model (ChB) which was adapted to allow the prediction of char burnout of biomass-coal blends under typical pf combustion conditions. The burnout performance of four blend compositions for each biomass were modelled (5%, 10%, 20% and 30%). In practice, the low heating-value of biomass produces a lower flame temperature which can lead to lower levels of char burn-out. The effect is closely linked with the type of biomass used. 36 refs., 4 figs., 1 tab.

  7. Flame oxidation of stainless steel felt enhances anodic biofilm formation and current output in bioelectrochemical systems.

    Science.gov (United States)

    Guo, Kun; Donose, Bogdan C; Soeriyadi, Alexander H; Prévoteau, Antonin; Patil, Sunil A; Freguia, Stefano; Gooding, J Justin; Rabaey, Korneel

    2014-06-17

    Stainless steel (SS) can be an attractive material to create large electrodes for microbial bioelectrochemical systems (BESs), due to its low cost and high conductivity. However, poor biocompatibility limits its successful application today. Here we report a simple and effective method to make SS electrodes biocompatible by means of flame oxidation. Physicochemical characterization of electrode surface indicated that iron oxide nanoparticles (IONPs) were generated in situ on an SS felt surface by flame oxidation. IONPs-coating dramatically enhanced the biocompatibility of SS felt and consequently resulted in a robust electroactive biofilm formation at its surface in BESs. The maximum current densities reached at IONPs-coated SS felt electrodes were 16.5 times and 4.8 times higher than the untreated SS felts and carbon felts, respectively. Furthermore, the maximum current density achieved with the IONPs-coated SS felt (1.92 mA/cm(2), 27.42 mA/cm(3)) is one of the highest current densities reported thus far. These results demonstrate for the first time that flame oxidized SS felts could be a good alternative to carbon-based electrodes for achieving high current densities in BESs. Most importantly, high conductivity, excellent mechanical strength, strong chemical stability, large specific surface area, and comparatively low cost of flame oxidized SS felts offer exciting opportunities for scaling-up of the anodes for BESs.

  8. Scaling of turbulent flame speed for expanding flames with Markstein diffusion considerations.

    Science.gov (United States)

    Chaudhuri, Swetaprovo; Wu, Fujia; Law, Chung K

    2013-09-01

    In this paper we clarify the role of Markstein diffusivity, which is the product of the planar laminar flame speed and the Markstein length, on the turbulent flame speed and its scaling, based on experimental measurements on constant-pressure expanding turbulent flames. Turbulent flame propagation data are presented for premixed flames of mixtures of hydrogen, methane, ethylene, n-butane, and dimethyl ether with air, in near-isotropic turbulence in a dual-chamber, fan-stirred vessel. For each individual fuel-air mixture presented in this work and the recently published iso-octane data from Leeds, normalized turbulent flame speed data of individual fuel-air mixtures approximately follow a Re_{T,f}^{0.5} scaling, for which the average radius is the length scale and thermal diffusivity is the transport property of the turbulence Reynolds number. At a given Re_{T,f}^{}, it is experimentally observed that the normalized turbulent flame speed decreases with increasing Markstein number, which could be explained by considering Markstein diffusivity as the leading dissipation mechanism for the large wave number flame surface fluctuations. Consequently, by replacing thermal diffusivity with the Markstein diffusivity in the turbulence Reynolds number definition above, it is found that normalized turbulent flame speeds could be scaled by Re_{T,M}^{0.5} irrespective of the fuel, equivalence ratio, pressure, and turbulence intensity for positive Markstein number flames.

  9. Aromatics Oxidation and Soot Formation in Flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J. B.; Richter, H.

    2005-03-29

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and the growth process to polycyclic aromatic hydrocarbons (PAH) of increasing size, soot and fullerenes formation in flames. The overall objective of the experimental aromatics oxidation work is to extend the set of available data by measuring concentration profiles for decomposition intermediates such as phenyl, cyclopentadienyl, phenoxy or indenyl radicals which could not be measured with molecular-beam mass spectrometry to permit further refinement and testing of benzene oxidation mechanisms. The focus includes PAH radicals which are thought to play a major role in the soot formation process while their concentrations are in many cases too low to permit measurement with conventional mass spectrometry. The radical species measurements are used in critical testing and improvement of a kinetic model describing benzene oxidation and PAH growth. Thermodynamic property data of selected species are determined computationally, for instance using density functional theory (DFT). Potential energy surfaces are explored in order to identify additional reaction pathways. The ultimate goal is to understand the conversion of high molecular weight compounds to nascent soot particles, to assess the roles of planar and curved PAH and relationships between soot and fullerenes formation. The specific aims are to characterize both the high molecular weight compounds involved in the nucleation of soot particles and the structure of soot including internal nanoscale features indicative of contributions of planar and/or curved PAH to particle inception.

  10. Aromatics Oxidation and Soot Formation in Flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J. B.; Richter, H.

    2005-03-29

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and the growth process to polycyclic aromatic hydrocarbons (PAH) of increasing size, soot and fullerenes formation in flames. The overall objective of the experimental aromatics oxidation work is to extend the set of available data by measuring concentration profiles for decomposition intermediates such as phenyl, cyclopentadienyl, phenoxy or indenyl radicals which could not be measured with molecular-beam mass spectrometry to permit further refinement and testing of benzene oxidation mechanisms. The focus includes PAH radicals which are thought to play a major role in the soot formation process while their concentrations are in many cases too low to permit measurement with conventional mass spectrometry. The radical species measurements are used in critical testing and improvement of a kinetic model describing benzene oxidation and PAH growth. Thermodynamic property data of selected species are determined computationally, for instance using density functional theory (DFT). Potential energy surfaces are explored in order to identify additional reaction pathways. The ultimate goal is to understand the conversion of high molecular weight compounds to nascent soot particles, to assess the roles of planar and curved PAH and relationships between soot and fullerenes formation. The specific aims are to characterize both the high molecular weight compounds involved in the nucleation of soot particles and the structure of soot including internal nanoscale features indicative of contributions of planar and/or curved PAH to particle inception.

  11. Pressurised coal combustion in a pilot scale facility

    Energy Technology Data Exchange (ETDEWEB)

    Hardalupas, Y.; Prassas, I.; Taylor, A.M.K.P.; Whitelaw, J.H. [Imperial College of Science, Technology and Medicine, London (United Kingdom). Mechanical Engineering Dept.

    1998-12-31

    Flux, velocity and the temperature characteristics of burning coal particles were measured simultaneously in the primary combustion zone of the swirl-stabilised burner of the pilot-scale furnace constructed at Imperial College. The furnace was designed to operate at pressures up to 5 bar and at thermal loadings up to 150 kW, and provision was made for optical access in the near-burner region of the combustor. The combined instrument used a novel technique for the simultaneous measurement of velocity and size, as well as the angle between the trajectory of the particle and an axis of reference, of particles of arbitrary shape, the so-called Shadow Doppler Velocimeter; and a two-colour pyrometer, for the simultaneous measurement of velocity, size and temperature of burning pulverised coal particles. The experiments performed consisted of: measurement of the gaseous phase as a function of the swirl number; measurement of the size, velocity, and temperature of burning coal particles as a function of the swirl number; and measurement of the size and velocity of burning coal particles inside the pressurised coal combustor at atmospheric pressure. The experiments were to evaluate and improve and further develop existing instrumentation with potential to be used in pressurised combustors; provide a database of accurate measurements for the needs of numerical models; and improve the understanding of the fluid mechanics and combustion processes at atmospheric pressures. Results obtained using the optical instrumentation showed that in an open flame, evidence of particle centrifuging existed downstream of the quarl entry. The temperature of volatile flames was about 2250 K and that of the char below 2000 K. Measurements along radial profiles inside the coal combustor showed that the axial and tangential velocity of the particles was almost independent of size. 19 refs., 15 figs., 1 tab.

  12. Laminar Soot Processes Experiment Shedding Light on Flame Radiation

    Science.gov (United States)

    Urban, David L.

    1998-01-01

    The Laminar Soot Processes (LSP) experiment investigated soot processes in nonturbulent, round gas jet diffusion flames in still air. The soot processes within these flames are relevant to practical combustion in aircraft propulsion systems, diesel engines, and furnaces. However, for the LSP experiment, the flames were slowed and spread out to allow measurements that are not tractable for practical, Earth-bound flames.

  13. Flaming: More than a Necessary Evil for Academic Mailing Lists?

    Science.gov (United States)

    Wang, Hongjie

    1996-01-01

    States that although Internet "gurus" advocate that users refrain from "flaming," in fact, flaming permeates the Internet. Explores the nature of flaming in its characteristics and forms as seen in academic discussion groups. Argues that flaming educates the ignorant, tames the uncouth, and promotes effective communication. (PA)

  14. Uniform nanoparticles by flame-assisted spray pyrolysis (FASP) of low cost precursors

    Science.gov (United States)

    Rudin, Thomas; Wegner, Karsten; Pratsinis, Sotiris E.

    2011-07-01

    A new flame-assisted spray pyrolysis (FASP) reactor design is presented, which allows the use of inexpensive precursors and solvents (e.g., ethanol) for synthesis of nanoparticles (10-20 nm) with uniform characteristics. In this reactor design, a gas-assisted atomizer generates the precursor solution spray that is mixed and combusted with externally fed inexpensive fuel gases (acetylene or methane) at a defined height above the atomizing nozzle. The gaseous fuel feed can be varied to control the combustion enthalpy content of the flame and onset of particle formation. This way, the enthalpy density of the flame is decoupled from the precursor solution composition. Low enthalpy content precursor solutions are prone to synthesis of non-uniform particles (e.g., bimodal particle size distribution) by standard flame spray pyrolysis (FSP) processes. For example, metal nitrates in ethanol typically produce nanosized particles by gas-to-particle conversion along with larger particles by droplet-to-particle conversion. The present FASP design facilitates the use of such low enthalpy precursor solutions for synthesis of homogeneous nanopowders by increasing the combustion enthalpy density of the flame with low-cost, gaseous fuels. The effect of flame enthalpy density on product properties in the FASP configuration is explored by the example of Bi2O3 nanoparticles produced from bismuth nitrate in ethanol. Product powders were characterized by nitrogen adsorption, X-ray diffraction, X-ray disk centrifuge, and transmission electron microscopy. Homogeneous Bi2O3 nanopowders were produced both by increasing the gaseous fuel content and, most notably, by cutting the air entrainment prior to ignition of the spray.

  15. Optimization of the process of plasma ignition of coal

    Energy Technology Data Exchange (ETDEWEB)

    Peregudov, V.S. [Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2009-04-15

    Results are given of experimental and theoretical investigations of plasma ignition of coal as a result of its thermochemical preparation in application to the processes of firing up a boiler and stabilizing the flame combustion. The experimental test bed with a commercial-scale burner is used for determining the conditions of plasma ignition of low-reactivity high-ash anthracite depending on the concentration of coal in the air mixture and velocity of the latter. The calculations produce an equation (important from the standpoint of practical applications) for determining the energy expenditure for plasma ignition of coal depending on the basic process parameters. The tests reveal the difficulties arising in firing up a boiler with direct delivery of pulverized coal from the mill to furnace. A scheme is suggested, which enables one to reduce the energy expenditure for ignition of coal and improve the reliability of the process of firing up such a boiler. Results are given of calculation of plasma thermochemical preparation of coal under conditions of lower concentration of oxygen in the air mixture.

  16. Combustion char morphology related to combustion temperature and coal petrography

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, P.; Petersen, H.I.; Thomsen, E. [Geological Survey of Denmark, Copenhagen (Denmark)

    1996-07-01

    Chars produced from different reactors were found to lack consistency of morphological charactersitics. Therefore, the morphology of chars sampled from various laboratory-scale reactors operating at temperatures from 800 to {gt} 1400{degree}C, together with chars collected directly in the flame zone in a full-scale pulverised fuel combustion experiment, was examined. A coal and coal blend dominated by vitrinite-rich microlithotypes together with four coals dominated by inertinite-rich microlithotypes were used to produce the combustion chars. Char samples produced at temperatures above {approximately} 1300{degree}C have a morphotype composition very similar to the composition of the full-scale char samples, whereas the morphotype compositions of those produced at {approximately} 1550{degree}C or lower are significantly different. Correlation between coal petrography and char morphology and determination of char reactivity should thus be attempted only using chars produced at temperatures comparable with those for the intended use of the coal. A clear distinction between the high-temperature char samples (burnout 50-60wt% daf) emerges which is related mainly to the parent coal petrography and probably secondarily to the rank. Vitrite, clarite and vitrinertie V may be correlated with the porous tenuisphere and crassisphere morphotypes, whereas inertite, durite, vitrinertite I, duroclarite and charodurite may be correlated with the crassinetwork-mixed-network-mixed morphotype group. 29 refs., 7 figs., 7 tabs.

  17. Active explosion barrier performance against methane and coal dust explosions

    Institute of Scientific and Technical Information of China (English)

    J J L du Plessis

    2015-01-01

    Preventing the propagation of methane or coal dust explosions through the use of active explosion-suppression systems remains one of the most underutilised explosion controls in underground coal mines. As part of the effort to develop better technologies to safeguard mines, the use of active barrier systems was investigated at Kloppersbos in South Africa. The system is designed to meet the requirements of the European Standard (EN 14591-4 2007) as well as the Mine Safety Standardisation in the Ministry of Coal Industry, Coal Industrial l Standard of the Peoples Republic of China (MT 694-1997). From the tests conducted, it can be concluded that the ExploSpot System was successful in stopping flame propagation for both methane and methane and coal dust hybrid explosions when ammonium phosphate powder was used as the suppression material. The use of this barrier will provide coal mine management with an additional explosion control close to the point of ignition and may find application within longwall faces further protecting mines against the risk of an explosion propagating throughout a mine.

  18. Coal char fragmentation during pulverized coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, L.L.

    1995-07-01

    A series of investigations of coal and char fragmentation during pulverized coal combustion is reported for a suite of coals ranging in rank from lignite to low-volatile (lv) bituminous coal under combustion conditions similar to those found in commercial-scale boilers. Experimental measurements are described that utilize identical particle sizing characteristics to determine initial and final size distributions. Mechanistic interpretation of the data suggest that coal fragmentation is an insignificant event and that char fragmentation is controlled by char structure. Chars forming cenospheres fragment more extensively than solid chars. Among the chars that fragment, large particles produce more fine material than small particles. In all cases, coal and char fragmentation are seen to be sufficiently minor as to be relatively insignificant factors influencing fly ash size distribution, particle loading, and char burnout.

  19. Upgraded Coal Interest Group

    Energy Technology Data Exchange (ETDEWEB)

    Evan Hughes

    2009-01-08

    The Upgraded Coal Interest Group (UCIG) is an EPRI 'users group' that focuses on clean, low-cost options for coal-based power generation. The UCIG covers topics that involve (1) pre-combustion processes, (2) co-firing systems and fuels, and (3) reburn using coal-derived or biomass-derived fuels. The UCIG mission is to preserve and expand the economic use of coal for energy. By reducing the fuel costs and environmental impacts of coal-fired power generation, existing units become more cost effective and thus new units utilizing advanced combustion technologies are more likely to be coal-fired.

  20. Co-utilisation of coal and biomass

    Energy Technology Data Exchange (ETDEWEB)

    Michal Kubacki; Andrew B. Ross; Jenny M. Jones; Alan Williams [University of Leeds, Leeds (United Kingdom). Energy and Resources Research Institute, School of Process

    2007-07-01

    Co-utilisation of coal and biomass for energy production results in pollutant reduction. Most notable is the impact on NOx, SOx, volatile organic compounds (VOC) and polyaromatic hydrocarbons (PAH). The aim of this study is to improve our understanding of the synergy in toxic organic emission reduction from co-firing or co-gasifying coal and biomass. A new technique was developed to study co-pyrolysis, heated wire mesh pyrolysis coupled to a GC-mass-spectrometer via a probe, which can sample at varying heights from the pyrolysing fuel. The results from this technique were compared to more conventional pyrolysis-GC-MS as well as thermogravimetric (TGA) and batch reactor studies. Co-combustion was studied by TGA and by burning briquettes supported on a needle in a methane air flame. A range of coals of varying rank, different biomass, as well as model compounds were used. Results show that non-additive combustion behaviour is not easily explained by studying devolatilisation because of the difficulty in replicating the conditions of temperature profile and residence time experienced by the volatiles. Thus, conflicting behaviour is exhibited depending upon pyrolysis technique. However, the atmosphere during experiments appears to be more important. Non-additive combustion for both powdered and pelletised fuels was seen by TGA and studies in a methane-air burner. The coal ignites and burns at a lower temperature because of the interaction with the biomass volatile combustion region. Thus it is proposed that the reduction in emissions from co-combustion arises from enhanced reaction of the coal volatiles by mixing with biomass volatiles in a hot oxidising atmosphere. 14 refs., 11 figs., 2 tabs.

  1. The dilution effect on the extinction of wall diffusion flame

    Directory of Open Access Journals (Sweden)

    Ghiti Nadjib

    2014-12-01

    Full Text Available The dynamic process of the interaction between a turbulent jet diffusion methane flame and a lateral wall was experimentally studied. The evolution of the flame temperature field with the Nitrogen dilution of the methane jet flame was examined. The interaction between the diffusion flame and the lateral wall was investigated for different distance between the wall and the central axes of the jet flame. The dilution is found to play the central role in the flame extinction process. The flame response as the lateral wall approaches from infinity and the increasing of the dilution rate make the flame extinction more rapid than the flame without dilution, when the nitrogen dilution rate increase the flame temperature decrease.

  2. Structure of a poly(ethylene) opposed flow diffusion flame

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, W.J.; Brown, N.J.; Sawyer, R.F.

    1980-08-01

    Structural measurements were obtained and compared with other investigations of diffusion flames. Departures from the commonly assumed collapsed flame model of laminar diffusion flames were observed in terms of excessive CO concentrations and oxygen penetration into the fuel side of the flame. An upper bound on the importance of oxygen diffusion to the fuel surface and subsequent surface oxidation was placed at 20% of the energy required for fuel pyrolysis, with the remainder of the energy being delivered to the surface from the flame through heat transfer processes. As the oxygen concentration in the oxidizer flow was decreased and extinction conditions approached, the CO/CO/sub 2/ ratio at the flame increased slightly, the oxygen concentration at the luminous flame zone decreased, the flame stand-off distance decreased, and the flame temperature decreased. Radial similarity in the composition and temperature profiles was established experimentally which confirms predictions and greatly simplifies the modeling of the opposed flow diffusion flame.

  3. Visualizations of Gas fuel Jet and Combustion Flame on Hydrogen Rotary Engine

    OpenAIRE

    田端, 道彦; 香川, 良二

    2011-01-01

    [Abstract] In this paper, it is a purpose to obtain basic information of a hydrogen jet and combustion flame characteristics of the hydrogen rotary engine. The jet characteristics of the hydrogen gas injector were measured by using the high-speed shadowgraph method. As the result, the jet penetration of the low density gas was weak. The mixing of the direction of the jet axis was disturbed for the low jet pressure. Next, the combustion flame propagation of the hydrogen rotary engine was visua...

  4. International perspectives on coal preparation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The report consists of the vugraphs from the presentations which covered the following topics: Summaries of the US Department of Energy`s coal preparation research programs; Preparation trends in Russia; South African coal preparation developments; Trends in hard coal preparation in Germany; Application of coal preparation technology to oil sands extraction; Developments in coal preparation in China; and Coal preparation in Australia.

  5. Aromatics oxidation and soot formation in flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T. [Massachusetts Institute of Technology, Cambridge (United States)

    1993-12-01

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify and to determine or confirm rate constants for the main benzene oxidation reactions in flames, and to characterize fullerenes and their formation mechanisms and kinetics.

  6. Systems and methods for controlling flame instability

    KAUST Repository

    Cha, Min Suk

    2016-07-21

    A system (62) for controlling flame instability comprising: a nozzle (66) coupled to a fuel supply line (70), an insulation housing (74) coupled to the nozzle, a combustor (78) coupled to the nozzle via the insulation housing, where the combustor is grounded (80), a pressure sensor (82) coupled to the combustor and configured to detect pressure in the combustor, and an instability controlling assembly coupled to the pressure sensor and to an alternating current power supply (86), where, the instability controlling assembly can control flame instability of a flame in the system based on pressure detected by the pressure sensor.

  7. Coal Combustion Science

    Energy Technology Data Exchange (ETDEWEB)

    Hardesty, D.R. (ed.); Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. (Sandia National Labs., Livermore, CA (United States))

    1991-08-01

    The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency Coal Combustion Science Project. Specific tasks for this activity include: (1) coal devolatilization - the objective of this risk is to characterize the physical and chemical processes that constitute the early devolatilization phase of coal combustion as a function of coal type, heating rate, particle size and temperature, and gas phase temperature and oxidizer concentration; (2) coal char combustion -the objective of this task is to characterize the physical and chemical processes involved during coal char combustion as a function of coal type, particle size and temperature, and gas phase temperature and oxygen concentration; (3) fate of mineral matter during coal combustion - the objective of this task is to establish a quantitative understanding of the mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distribution of mineral species in the unreacted coal, and the local gas temperature and composition.

  8. NUMERICAL SIMULATION OF THE GROWTH OF NANOPARTICLES IN A FLAME CVD PROCESS

    Institute of Scientific and Technical Information of China (English)

    Lixi Wang; Si Chen; Hongyong Xie

    2004-01-01

    The growth of titania nanoparticles in a flame CVD process has been simulated by computational fluid dynamics, based on the change rate of particle number density due to their collisions calculated from an integral collision kernel. The assumptions made on constant particle volume density nv (nd3), constant density of particle surface area ns (nd2), and constant entity nd2.5 in coagulation process have been examined. Comparisons have been made on particle size distribution between measurement results and predictions from present model of particle growth and Kruis model of particle dynamics for titania nanoparticles synthesized by the flame CVD process. Effects of operational parameters such as O2 mole fraction and particle number density on mean particle size and size distribution have been discussed.

  9. Novel Flame-Based Synthesis of Nanowires for Multifunctional Application

    Science.gov (United States)

    2015-05-13

    laser-based diagnostics for in-situ Raman characterization of as- synthesized nanomaterials, (iv) flame synthesis of graphene , (v) flame synthesis of...laser- based diagnostics for in-situ Raman characterization of as-synthesized nanomaterials, (iv) flame synthesis of graphene , (v) flame synthesis of...Stephen D. Tse, Manish Chhowalla, Bernard H. Kear. Role of substrate, temperature, and hydrogen on the flame synthesis of graphene films, Proceedings

  10. Acoustically Forced Coaxial Hydrogen / Liquid Oxygen Jet Flames

    Science.gov (United States)

    2016-05-15

    visualized for both reacting and nonreacting cases. The jet flame was studied unforced, without acoustics , and forced, with transverse acoustic waves in...liquid rocket injector flames react to acoustic waves . In this study, a representative coaxial gaseous hydrogen / liquid oxygen (LOX) jet flame is...hydrogen / liquid oxygen (LOX) jet flame is visualized for both reacting and nonreacting cases. The jet flame was studied unforced, without acoustics , and

  11. Numerical simulations of flame dynamics in the near-field of high-Reynolds number jets

    Science.gov (United States)

    Venugopal, Rishikesh

    Recent experiments in diesel jet flames show that flame lift-off has a significant influence on pollutant formation. Lift-off occurs in the near-field of the jet, which is characterized by complex interactions between turbulence and chemistry. Commonly employed modeling approaches based on Reynolds-averaged Navier-Stokes (RANS) simulations are limited in their capability to predict transient and steady lift-off phenomena, as they ignore effects due to unsteadiness and curvature that are inherent in the near-field. In the present work, we perform numerical investigations of localized flame dynamics in the near-field (x/d diesel engine applications. The primary focus is on the exploration of unsteady extinction/reignition phenomena. A dual approach involving large-eddy simulation (LES) of a 70,000-Re variable-density isothermal gaseous fuel jet, and studies of flame-vortex interactions and unsteady flamelets, under diesel engine conditions, is employed in this work. Results from flame-vortex interaction studies show that in the near-field (x/d 1.0) in the jet near-field,temporary flame weakening/recovery events are likely to occur. Steady flamelet models provide reasonable estimates of the mean temperature, and mean mass fractions of the major species and unburned hydrocarbons (UHCs), but are inadequate for the prediction of mean NO mass fractions. Extrapolation of the analysis to jets with higher global strain rates shows that unsteady effects on the localized flame dynamics are important for the prediction of transient and steady lift-off behavior.

  12. Simulation and analysis of the soot particle size distribution in a turbulent nonpremixed flame

    KAUST Repository

    Lucchesi, Marco

    2017-02-05

    A modeling framework based on Direct Simulation Monte Carlo (DSMC) is employed to simulate the evolution of the soot particle size distribution in turbulent sooting flames. The stochastic reactor describes the evolution of soot in fluid parcels following Lagrangian trajectories in a turbulent flow field. The trajectories are sampled from a Direct Numerical Simulation (DNS) of a n-heptane turbulent nonpremixed flame. The DSMC method is validated against experimentally measured size distributions in laminar premixed flames and found to reproduce quantitatively the experimental results, including the appearance of the second mode at large aggregate sizes and the presence of a trough at mobility diameters in the range 3–8 nm. The model is then applied to the simulation of soot formation and growth in simplified configurations featuring a constant concentration of soot precursors and the evolution of the size distribution in time is found to depend on the intensity of the nucleation rate. Higher nucleation rates lead to a higher peak in number density and to the size distribution attaining its second mode sooner. The ensemble-averaged PSDF in the turbulent flame is computed from individual samples of the PSDF from large sets of Lagrangian trajectories. This statistical measure is equivalent to time-averaged, scanning mobility particle size (SMPS) measurements in turbulent flames. Although individual trajectories display strong bimodality as in laminar flames, the ensemble-average PSDF possesses only one mode and a long, broad tail, which implies significant polydispersity induced by turbulence. Our results agree very well with SMPS measurements available in the literature. Conditioning on key features of the trajectory, such as mixture fraction or radial locations does not reduce the scatter in the size distributions and the ensemble-averaged PSDF remains broad. The results highlight and explain the important role of turbulence in broadening the size distribution of

  13. Heat release and flame structure measurements of self-excited acoustically-driven premixed methane flames

    Energy Technology Data Exchange (ETDEWEB)

    Kopp-Vaughan, Kristin M.; Tuttle, Steven G.; Renfro, Michael W. [Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Rd, U-3139, Storrs, CT 06269 (United States); King, Galen B. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907 (United States)

    2009-10-15

    An open-open organ pipe burner (Rijke tube) with a bluff-body ring was used to create a self-excited, acoustically-driven, premixed methane-air conical flame, with equivalence ratios ranging from 0.85 to 1.05. The feed tube velocities corresponded to Re = 1780-4450. Coupled oscillations in pressure, velocity, and heat release from the flame are naturally encouraged at resonant frequencies in the Rijke tube combustor. This coupling creates sustainable self-excited oscillations in flame front area and shape. The period of the oscillations occur at the resonant frequency of the combustion chamber when the flame is placed {proportional_to}1/4 of the distance from the bottom of the tube. In this investigation, the shape of these acoustically-driven flames is measured by employing both OH planar laser-induced fluorescence (PLIF) and chemiluminescence imaging and the images are correlated to simultaneously measured pressure in the combustor. Past research on acoustically perturbed flames has focused on qualitative flame area and heat release relationships under imposed velocity perturbations at imposed frequencies. This study reports quantitative empirical fits with respect to pressure or phase angle in a self-generated pressure oscillation. The OH-PLIF images were single temporal shots and the chemiluminescence images were phase averaged on chip, such that 15 exposures were used to create one image. Thus, both measurements were time resolved during the flame oscillation. Phase-resolved area and heat release variations throughout the pressure oscillation were computed. A relation between flame area and the phase angle before the pressure maximum was derived for all flames in order to quantitatively show that the Rayleigh criterion was satisfied in the combustor. Qualitative trends in oscillating flame area were found with respect to feed tube flow rates. A logarithmic relation was found between the RMS pressure and both the normalized average area and heat release rate

  14. Direct numerical simulations of non-premixed ethylene-air flames: Local flame extinction criterion

    KAUST Repository

    Lecoustre, Vivien R.

    2014-11-01

    Direct Numerical Simulations (DNS) of ethylene/air diffusion flame extinctions in decaying two-dimensional turbulence were performed. A Damköhler-number-based flame extinction criterion as provided by classical large activation energy asymptotic (AEA) theory is assessed for its validity in predicting flame extinction and compared to one based on Chemical Explosive Mode Analysis (CEMA) of the detailed chemistry. The DNS code solves compressible flow conservation equations using high order finite difference and explicit time integration schemes. The ethylene/air chemistry is simulated with a reduced mechanism that is generated based on the directed relation graph (DRG) based methods along with stiffness removal. The numerical configuration is an ethylene fuel strip embedded in ambient air and exposed to a prescribed decaying turbulent flow field. The emphasis of this study is on the several flame extinction events observed in contrived parametric simulations. A modified viscosity and changing pressure (MVCP) scheme was adopted in order to artificially manipulate the probability of flame extinction. Using MVCP, pressure was changed from the baseline case of 1 atm to 0.1 and 10 atm. In the high pressure MVCP case, the simulated flame is extinction-free, whereas in the low pressure MVCP case, the simulated flame features frequent extinction events and is close to global extinction. Results show that, despite its relative simplicity and provided that the global flame activation temperature is correctly calibrated, the AEA-based flame extinction criterion can accurately predict the simulated flame extinction events. It is also found that the AEA-based criterion provides predictions of flame extinction that are consistent with those provided by a CEMA-based criterion. This study supports the validity of a simple Damköhler-number-based criterion to predict flame extinction in engineering-level CFD models. © 2014 The Combustion Institute.

  15. Coal blending scheduling in coal preparation plant based on multi-sensor information fusion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, L.; Yu, H.; Wang, Y. [CUMT, Xuzhou (China). School of Information and Electrical Engineering

    2004-01-01

    It is important to research on a reasonable blending schedule according to the customer requirement and the practice of products in coal preparation plant. In order to solve this problem, a mathematic model was set up on the basis of analysing coal blending schedule. Multi-sensors information fusion was used to monitor the density and the amount of coal. The genetic algorithm was used to solve the nonlinear function in the maths model. A satisfied result was obtained by simulating test. 8 refs., 2 figs.

  16. High pressure flame system for pollution studies with results for methane-air diffusion flames

    Science.gov (United States)

    Miller, I. M.; Maahs, H. G.

    1977-01-01

    A high pressure flame system was designed and constructed for studying nitrogen oxide formation in fuel air combustion. Its advantages and limitations were demonstrated by tests with a confined laminar methane air diffusion flame over the pressure range from 1 to 50 atm. The methane issued from a 3.06 mm diameter port concentrically into a stream of air contained within a 20.5 mm diameter chimney. As the combustion pressure is increased, the flame changes in shape from wide and convex to slender and concave, and there is a marked increase in the amount of luminous carbon. The height of the flame changes only moderately with pressure.

  17. Coal fires in China

    Institute of Scientific and Technical Information of China (English)

    CHE Yao(车遥); HUANG Wen-hui(黄文辉); ZHANG Ai-yun(张爱云)

    2004-01-01

    Coal fires have a very long history in China; the oldest coal fires have being burning for many million years. Up to now more than 56 coal fires spots were distinguished. They mainly locate in West-North of China, North of China and East-North of China. About millions of tons of coal have been burned in fires every year. Xinjiang Autonomy is the most serious region in coal fires as it has 38 coal fires spots and about 6.85 million tons of coal was burned every year. Coal fires in China ignited by wildfires, spontaneous combustion and human being during mining activities. These fires have released about 0.9 million tons of gasses (including CO, CO2, SO2, NO2 CH4, CO2, H2S etc.) into the atmosphere every year, most of which are brought to the east by wind and resulting more heavier air pollution in northern China.

  18. Continuous coal processing method

    Science.gov (United States)

    Ryason, P. R.

    1980-06-01

    A coal pump is provided in which solid coal is heated in the barrel of an extruder under pressure to a temperature at which the coal assumes plastic properties. The coal is continuously extruded, without static zones, using, for example, screw extrusion preferably without venting through a reduced diameter die to form a dispersed spray. As a result, the dispersed coal may be continuously injected into vessels or combustors at any pressure up to the maximum pressure developed in the extrusion device. The coal may be premixed with other materials such as desulfurization aids or reducible metal ores so that reactions occur, during or after conversion to its plastic state. Alternatively, the coal may be processed and caused to react after extrusion, through the die, with, for example, liquid oxidizers, whereby a coal reactor is provided.

  19. Nitrogen in Chinese coals

    Science.gov (United States)

    Wu, D.; Lei, J.; Zheng, B.; Tang, X.; Wang, M.; Hu, Jiawen; Li, S.; Wang, B.; Finkelman, R.B.

    2011-01-01

    Three hundred and six coal samples were taken from main coal mines of twenty-six provinces, autonomous regions, and municipalities in China, according to the resource distribution and coal-forming periods as well as the coal ranks and coal yields. Nitrogen was determined by using the Kjeldahl method at U. S. Geological Survey (USGS), which exhibit a normal frequency distribution. The nitrogen contents of over 90% Chinese coal vary from 0.52% to 1.41% and the average nitrogen content is recommended to be 0.98%. Nitrogen in coal exists primarily in organic form. There is a slight positive relationship between nitrogen content and coal ranking. ?? 2011 Science Press, Institute of Geochemistry, CAS and Springer Berlin Heidelberg.

  20. Coal worker's pneumoconiosis

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000130.htm Coal worker's pneumoconiosis To use the sharing features on this page, please enable JavaScript. Coal worker's pneumoconiosis is a lung disease that results ...

  1. Fluidized coal combustion

    Science.gov (United States)

    Moynihan, P. I.; Young, D. L.

    1979-01-01

    Fluidized-bed coal combustion process, in which pulverized coal and limestone are burned in presence of forced air, may lead to efficient, reliable boilers with low sulfur dioxide and nitrogen dioxide emissions.

  2. TENORM: Coal Combustion Residuals

    Science.gov (United States)

    Burning coal in boilers to create steam for power generation and industrial applications produces a number of combustion residuals. Naturally radioactive materials that were in the coal mostly end up in fly ash, bottom ash and boiler slag.

  3. Chemicals from coal

    Energy Technology Data Exchange (ETDEWEB)

    Harold A. Wittcoff; Bryan G. Reuben; Jeffrey S. Plotkin

    2004-12-01

    This chapter contains sections titled: Chemicals from Coke Oven Distillate; The Fischer-Tropsch Reaction; Coal Hydrogenation; Substitute Natural Gas (SNG); Synthesis Gas Technology; Calcium Carbide; Coal and the Environment; and Notes and References

  4. Modeling studies of a turbulent pulsed jet flame using LES/PDF

    Science.gov (United States)

    Zhang, Pei; Wang, Haifeng

    2015-11-01

    The combustion field in a pulsed turbulent piloted jet flame is studied using an advanced large eddy simulation (LES) / probability density function (PDF) method. Measurement data with a joint OH-PLIF/OH* chemiluminescence/LDV system are available including the temporal series of the axial velocity and planar OH images. A time-dependent inflow condition is specified based on the measurement data. A direct comparison of the mean and rms velocities from the calculations and from the measurement shows a satisfactory prediction of the flow fields by using the employed modeling methods. The predicted OH mass fractions are compared qualitatively with the measured OH images at selected temporal and spatial locations. The comparison shows a good agreement. Conditional quantities and flame index are extracted from the simulations to examine the bimodal and multi-regime combustion dynamics in the flame. This paper is based upon work supported by the National Science Foundation under Grant No. CBET-1336075.

  5. An Investigation of a Hybrid Mixing Timescale Model for PDF Simulations of Turbulent Premixed Flames

    Science.gov (United States)

    Zhou, Hua; Kuron, Mike; Ren, Zhuyin; Lu, Tianfeng; Chen, Jacqueline H.

    2016-11-01

    Transported probability density function (TPDF) method features the generality for all combustion regimes, which is attractive for turbulent combustion simulations. However, the modeling of micromixing due to molecular diffusion is still considered to be a primary challenge for TPDF method, especially in turbulent premixed flames. Recently, a hybrid mixing rate model for TPDF simulations of turbulent premixed flames has been proposed, which recovers the correct mixing rates in the limits of flamelet regime and broken reaction zone regime while at the same time aims to properly account for the transition in between. In this work, this model is employed in TPDF simulations of turbulent premixed methane-air slot burner flames. The model performance is assessed by comparing the results from both direct numerical simulation (DNS) and conventional constant mechanical-to-scalar mixing rate model. This work is Granted by NSFC 51476087 and 91441202.

  6. Experimental and numerical investigation of fuel mixing effects on soot structures in counterflow diffusion flames

    KAUST Repository

    Choi, Byungchul

    2011-03-26

    Experimental and numerical analyses of laminar diffusion flames were performed to identify the effect of fuel mixing on soot formation in a counterflow burner. In this experiment, the volume fraction, number density, and particle size of soot were investigated using light extinction/scattering systems. The experimental results showed that the synergistic effect of an ethylene-propane flame is appreciable. Numerical simulations showed that the benzene (C6H6) concentration in mixture flames was higher than in ethylene-base flames because of the increase in the concentration of propargyl radicals. Methyl radicals were found to play an important role in the formation of propargyl, and the recombination of propargyl with benzene was found to lead to an increase in the number density for cases exhibiting synergistic effects. These results imply that methyl radicals play an important role in soot formation, particularly with regard to the number density. © 2011 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.

  7. Coal Extraction - Environmental Prediction

    Science.gov (United States)

    Cecil, C. Blaine; Tewalt, Susan J.

    2002-01-01

    Coal from the Appalachian region has supplied energy to the Nation for more than 200 years. Appalachian coal fueled America through a civil war and helped win two world wars. Appalachian coal has also provided fuel for keeping America warm in the winter and cool in the summer and has served as the basis for the steel, automobile, organic chemicals, chlorine, and aluminum industries. These benefits have not come without environmental costs, however. Coal extraction and utilization have had significant environmental impacts.

  8. Induced polarization signature of coal seam fires

    Science.gov (United States)

    Shao, Zhenlu; Revil, André; Mao, Deqiang; Wang, Deming

    2017-03-01

    Coal seam fires are a worldwide disaster of both ecological and economic importance. Their remote detection from the ground surface or using airborne techniques is required for developing efficient strategies to extinguish them. We investigate here the use of time-domain-induced polarization to localize coal seam fires. For laboratory experiments, we first introduce a modified time-domain-induced polarization methodology to quickly acquire and invert the secondary voltage distribution mapped after the shutdown of the primary current. A set of sandbox experiments is conducted in which coal is embedded into humidified sand. Raw coal alone generates significant induced polarization anomalies, above those shown by the sand. Even higher induced polarization anomalies are detected in presence of a coal seam fire. We postulate that the higher chargeability is due to the pyrolysis, which may enhance electronic polarization or the polarization associated with the cation exchange capacity (CEC) of the material. The position of the coal seam fire is well recovered inside the tank by inverting the secondary voltages in term of a source current density distribution. We also collected field data over a recognized coal seam fire in Colorado, USA. A chargeability anomaly (∼800 mV V-1) and a resistivity anomaly (∼1 Ohm m) are observed at the position of the coal seam fire. We propose a normalized burning front index (a scaled normalized chargeability) to image and localize, without ambiguity, the position of the coal seam fire in the subsurface. The 3-D reconstructed target is located below a negative self-potential anomaly (similarly to what is observed in laboratory experiments) and a temperature anomaly recorded at a depth of 30 cm.

  9. Direct Numerical Simulation of a Cavity-Stabilized Ethylene/Air Premixed Flame

    Science.gov (United States)

    Chen, Jacqueline; Konduri, Aditya; Kolla, Hemanth; Rauch, Andreas; Chelliah, Harsha

    2016-11-01

    Cavity flame holders have been shown to be important for flame stabilization in scramjet combustors. In the present study the stabilization of a lean premixed ethylene/air flame in a rectangular cavity at thermo-chemical conditions relevant to scramjet combustors is simulated using a compressible reacting multi-block direct numerical simulation solver, S3D, incorporating a 22 species ethylene-air reduced chemical model. The fuel is premixed with air to an equivalence ratio of 0.4 and enters the computational domain at Mach numbers between 0.3 and 0.6. An auxiliary inert channel flow simulation is used to provide the turbulent velocity profile at the inlet for the reacting flow simulation. The detailed interaction between intense turbulence, nonequilibrium concentrations of radical species formed in the cavity and mixing with the premixed main stream under density variations due to heat release rate and compressibility effects is quantified. The mechanism for flame stabilization is quantified in terms of relevant non-dimensional parameters, and detailed analysis of the flame and turbulence structure will be presented. We acknowledge the sponsorship of the AFOSR-NSF Joint Effort on Turbulent Combustion Model Assumptions and the DOE Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences.

  10. CFD modeling using PDF approach for investigating the flame length in rotary kilns

    Science.gov (United States)

    Elattar, H. F.; Specht, E.; Fouda, A.; Bin-Mahfouz, Abdullah S.

    2016-12-01

    Numerical simulations using computational fluid dynamics (CFD) are performed to investigate the flame length characteristics in rotary kilns using probability density function (PDF) approach. A commercial CFD package (ANSYS-Fluent) is employed for this objective. A 2-D axisymmetric model is applied to study the effect of both operating and geometric parameters of rotary kiln on the characteristics of the flame length. Three types of gaseous fuel are used in the present work; methane (CH4), carbon monoxide (CO) and biogas (50 % CH4 + 50 % CO2). Preliminary comparison study of 2-D modeling outputs of free jet flames with available experimental data is carried out to choose and validate the proper turbulence model for the present numerical simulations. The results showed that the excess air number, diameter of kiln air entrance, radiation modeling consideration and fuel type have remarkable effects on the flame length characteristics. Numerical correlations for the rotary kiln flame length are presented in terms of the studied kiln operating and geometric parameters within acceptable error.

  11. CFD modeling using PDF approach for investigating the flame length in rotary kilns

    Science.gov (United States)

    Elattar, H. F.; Specht, E.; Fouda, A.; Bin-Mahfouz, Abdullah S.

    2016-02-01

    Numerical simulations using computational fluid dynamics (CFD) are performed to investigate the flame length characteristics in rotary kilns using probability density function (PDF) approach. A commercial CFD package (ANSYS-Fluent) is employed for this objective. A 2-D axisymmetric model is applied to study the effect of both operating and geometric parameters of rotary kiln on the characteristics of the flame length. Three types of gaseous fuel are used in the present work; methane (CH4), carbon monoxide (CO) and biogas (50 % CH4 + 50 % CO2). Preliminary comparison study of 2-D modeling outputs of free jet flames with available experimental data is carried out to choose and validate the proper turbulence model for the present numerical simulations. The results showed that the excess air number, diameter of kiln air entrance, radiation modeling consideration and fuel type have remarkable effects on the flame length characteristics. Numerical correlations for the rotary kiln flame length are presented in terms of the studied kiln operating and geometric parameters within acceptable error.

  12. Theory of DDT in unconfined flames

    CERN Document Server

    Khokhlov, A M; Wheeler, J C; Wheeler, J Craig

    1996-01-01

    This paper outlines a theoretical approach for predicting the onset of detonation in unconfined turbulent flames which is relevant both to problems of terrestrial combustion and to thermonuclear burning in Type Ia supernovae. Two basic assumuptions are made: 1) the gradient mechanism is the inherent mechanism that leads to DDT in unconfined conditions, and 2) the sole mechanism for preparing the gradient in induction time is by turbulent mixing and local flame quenching. The criterion for DDT is derived in terms of the one-dimensional detonation wave thickness, the laminar flame speed, and the laminar flame thickness in the reactive gas. This approach gives a lower-bound criterion for DDT for conditions where shock preheating, wall effects, and interactions with obstacles are absent. Regions in parameter space where unconfined DDT can and cannot occur are determined. A subsequent paper will address these issues specifically in the astrophysical context.

  13. Coal geology, land use and human health in the People's Republic of China

    Energy Technology Data Exchange (ETDEWEB)

    Karlsen, A.W.; Schultz, A.C.; Warwick, P.D.; Podwysocki, S.M.; Lovern, V.S. (comps.) [US Geological Survey, Reston, VA (United States)

    2001-07-01

    The CD-ROM contains data in ArcView and pdf files on coal fields, coal mines, coal rank, coal production, and geology of China. It also shows ore deposits and oil and gas fields. There are data on high fluoride pollution sources and prevalence rates of dental fluorosis in China. Background information is given on political boundaries, counties, provinces, cities, urban areas, airfields, roads, railraods, the electrical power network, river networks, ecoregions and population density.

  14. Considerations on coal gasification

    Science.gov (United States)

    Franzen, J. E.

    1978-01-01

    Commercial processes for the gasification of coal with oxygen are discussed. The Koppers-Totzek process for the gasification of coal dust entrained in a stream of gasifying agents is described in particular detail. The outlook for future applications of coal gasification is presented.

  15. Prediction of coal hydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Labuschagne, B.C.J. [Council for Scientific and Industrial Research, Pretoria (South Africa). Div. of Energy Technology; Wheelock, T.D.; Guo, R.K.; David, H.T. [Iowa State Univ. of Science and Technology, Ames, IA (United States); Markuszewski, R. [Ames Lab., IA (United States)

    1988-12-31

    Many coals exhibit a certain degree of native hydrophobicity. The more hydrophobic coals (the higher-rank coals) are easily beneficiated by froth flotation or oil agglomeration, while the more hydrophilic coals (the lower-rank coals) are floated or agglomerated with difficulty. Coals of different ranks and often even of the same rank sometimes differ greatly in hydrophobicity as measured by contact angle or natural floatability. Although the degree of hydrophobicity of a coal is related to its rank and has been correlated with other surface properties of the coal , the known information is still not sufficient to allow a good estimation to be made of the hydrophobicity of a given coal and does not explain the variation of coal hydrophobicity as a function of rank. A statistical analysis of previously published data, as well as newly acquired data, shows that coal hydrophobicity correlates better with moisture content than with carbon content, and better with the moisture/carbon molar ratio than with the hydrogen/carbon or oxygen/carbon atomic ratios. These findings indicate that there is a strong association between hydrophobicity and coal moisture content.

  16. Coal production 1989

    Energy Technology Data Exchange (ETDEWEB)

    1990-11-29

    Coal Production 1989 provides comprehensive information about US coal production, the number of mines, prices, productivity, employment, reserves, and stocks to a wide audience including Congress, federal and state agencies, the coal industry, and the general public. 7 figs., 43 tabs.

  17. Flaming Pear Creative Pack1.0

    Institute of Scientific and Technical Information of China (English)

    Kane

    2003-01-01

    Flaming Pear是个一直给我留下深刻印象的软件开发公司。我以前评论过很多这个公司的插件,每一次都是不错的经历。同样的优良传统同样体现在Flaming Pear的新品Creative Pack1.0

  18. Temperature, Oxygen, and Soot-Volume-Fraction Measurements in a Turbulent C2H4-Fueled Jet Flame

    Energy Technology Data Exchange (ETDEWEB)

    Kearney, Sean P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Guildenbecher, Daniel Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Winters, Caroline [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Farias, Paul Abraham [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grasser, Thomas W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hewson, John C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    We present a detailed set of measurements from a piloted, sooting, turbulent C 2 H 4 - fueled diffusion flame. Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (CARS) is used to monitor temperature and oxygen, while laser-induced incandescence (LII) is applied for imaging of the soot volume fraction in the challenging jet-flame environment at Reynolds number, Re = 20,000. Single-laser shot results are used to map the mean and rms statistics, as well as probability densities. LII data from the soot-growth region of the flame are used to benchmark the soot source term for one-dimensional turbulence (ODT) modeling of this turbulent flame. The ODT code is then used to predict temperature and oxygen fluctuations higher in the soot oxidation region higher in the flame.

  19. NO concentration imaging in turbulent nonpremixed flames

    Energy Technology Data Exchange (ETDEWEB)

    Schefer, R.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.

  20. Synthesis of Nano-Particles in Flames

    DEFF Research Database (Denmark)

    Johannessen, Tue

    The scope of this work is to investigate the synthesis of aluminum oxide particles in flames from the combustion of an aluminum alkoxide precursor.A general introduction to particles formation in the gas phase is presented with emphasis on the mechanisms that control the particle morphology after...... for the analysis of particle formation in flames. Good results for a wide range of operating conditions were obtained. Therefore, the method should be useful as a tool for the optimization and/or design of flame processes for particle production.......The scope of this work is to investigate the synthesis of aluminum oxide particles in flames from the combustion of an aluminum alkoxide precursor.A general introduction to particles formation in the gas phase is presented with emphasis on the mechanisms that control the particle morphology after...... flame burner and a premixed burner with a precursor jet. The experimental setups and results are shown and discussed in detail. Alumina powder with specific surface area between 45 m2/g and 190 m2/g was obtained.Temperature and flow fields of the flame processes are analysed by numerical simulations...

  1. Conical quarl swirl stabilized non-premixed flames: flame and flow field interaction

    KAUST Repository

    Elbaz, Ayman M.

    2017-09-19

    The flame-flow field interaction is studied in non-premixed methane swirl flames stabilized in quartz quarl via simultaneous measurements of the flow field using a stereo PIV and OH-PLIF at 5 KHz repetition rate. Under the same swirl intensity, two flames with different fuel jet velocity were investigated. The time-averaged flow field shows a unique flow pattern at the quarl exit, where two recirculation vortices are formed; a strong recirculation zone formed far from the quarl exit and a larger recirculation zone extending inside the quarl. However, the instantaneous images show that, the flow pattern near the quarl exit plays a vital role in the spatial location and structure of the reaction zone. In the low fuel jet velocity flame, a pair of vortical structures, located precisely at the corners of the quarl exit, cause the flame to roll up into the central region of low speed flow, where the flame sheet then tracks the axial velocity fluctuations. The vorticity field reveals a vortical structure surrounding the reaction zones, which reside on a layer of low compressive strain adjacent to that vortical structure. In the high fuel jet velocity flame, initially a laminar flame sheet resides at the inner shear layer of the main jet, along the interface between incoming fresh gas and high temperature recirculating gas. Further downstream, vortex breakdown alters the flame sheet path toward the central flame region. The lower reaction zones show good correlation to the regions of maximum vorticity and track the regions of low compressive strain associated with the inner shear layer of the jet flow. In both flames the reactions zones conform the passage of the large structure while remaining inside the low speed regions or at the inner shear layer.

  2. Preparation of Flame Retardant Modified with Titanate for Asphalt Binder

    Directory of Open Access Journals (Sweden)

    Bo Li

    2014-01-01

    Full Text Available Improving the compatibility between flame retardant and asphalt is a difficult task due to the complex nature of the materials. This study explores a low dosage compound flame retardant and seeks to improve the compatibility between flame retardants and asphalt. An orthogonal experiment was designed taking magnesium hydroxide, ammonium polyphosphate, and melamine as factors. The oil absorption and activation index were tested to determine the effect of titanate on the flame retardant additive. The pavement performance test was conducted to evaluate the effect of the flame retardant additive. Oxygen index test was conducted to confirm the effect of flame retardant on flame ability of asphalt binder. The results of this study showed that the new composite flame retardant is more effective in improving the compatibility between flame retardant and asphalt and reducing the limiting oxygen index of asphalt binder tested in this study.

  3. The economics of coal

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    Global aspects of the production, consumption and trade in coal are described. World reserves and resources, production (both by region and country), international trade (exporters and importers), coal consumption (by region and sector), and the demand for primary energy (1960-1979). Each of the producing and consuming countries are discussed individually. The electricity sector and its future demand for coal, and the future demand for coking coal are covered. Prices for metallurgical and steam coal are also given. Statistics are presented in tables.

  4. Radionuclides in US coals

    Energy Technology Data Exchange (ETDEWEB)

    Bisselle, C. A.; Brown, R. D.

    1984-03-01

    The current state of knowledge with respect to radionuclide concentrations in US coals is discussed. Emphasis is placed on the levels of uranium in coal (and lignite) which are considered to represent a concern resulting from coal combustion; areas of the US where such levels have been found; and possible origins of high radionuclide levels in coal. The report reviews relevant studies and presents new data derived from a computerized search of radionuclide content in about 4000 coal samples collected throughout the coterminous US. 103 references, 5 figures, 5 tables.

  5. Autoignition and flame stabilisation processes in turbulent non-premixed hot coflow flames

    NARCIS (Netherlands)

    Oldenhof , E.

    2012-01-01

    This dissertation examines stabilisation processes in turbulent non-premixed jet flames, created by injecting gaseous fuel into a co-flowing stream of hot, low-oxygen combustion products. Being able to predict whether and how a flame achieves stable and reliable combustion is a matter of great pract

  6. Methane Formation by Flame-Generated Hydrogen Atoms in the Flame Ionization Detector

    DEFF Research Database (Denmark)

    Holm, Torkil; Madsen, Jørgen Øgaard

    1996-01-01

    The precombustion degradation of organic compounds in the flame ionization detector has been studied (1) by heating the additives in hydrogen in a quartz capillary and analyzing the reaction products by GC and (2) by following the degradation of the additives in a hydrogen flame, by means of a th...

  7. Modeling Candle Flame Behavior In Variable Gravity

    Science.gov (United States)

    Alsairafi, A.; Tien, J. S.; Lee, S. T.; Dietrich, D. L.; Ross, H. D.

    2003-01-01

    The burning of a candle, as typical non-propagating diffusion flame, has been used by a number of researchers to study the effects of electric fields on flame, spontaneous flame oscillation and flickering phenomena, and flame extinction. In normal gravity, the heat released from combustion creates buoyant convection that draws oxygen into the flame. The strength of the buoyant flow depends on the gravitational level and it is expected that the flame shape, size and candle burning rate will vary with gravity. Experimentally, there exist studies of candle burning in enhanced gravity (i.e. higher than normal earth gravity, g(sub e)), and in microgravity in drop towers and space-based facilities. There are, however, no reported experimental data on candle burning in partial gravity (g model of the candle flame, buoyant forces were neglected. The treatment of momentum equation was simplified using a potential flow approximation. Although the predicted flame characteristics agreed well with the experimental results, the model cannot be extended to cases with buoyant flows. In addition, because of the use of potential flow, no-slip boundary condition is not satisfied on the wick surface. So there is some uncertainty on the accuracy of the predicted flow field. In the present modeling effort, the full Navier-Stokes momentum equations with body force term is included. This enables us to study the effect of gravity on candle flames (with zero gravity as the limiting case). In addition, we consider radiation effects in more detail by solving the radiation transfer equation. In the previous study, flame radiation is treated as a simple loss term in the energy equation. Emphasis of the present model is on the gas-phase processes. Therefore, the detailed heat and mass transfer phenomena inside the porous wick are not treated. Instead, it is assumed that a thin layer of liquid fuel coated the entire wick surface during the burning process. This is the limiting case that the mass

  8. Coal; Le charbon

    Energy Technology Data Exchange (ETDEWEB)

    Teissie, J.; Bourgogne, D. de; Bautin, F. [TotalFinaElf, La Defense, 92 - Courbevoie (France)

    2001-12-15

    Coal world production represents 3.5 billions of tons, plus 900 millions of tons of lignite. 50% of coal is used for power generation, 16% by steel making industry, 5% by cement plants, and 29% for space heating and by other industries like carbo-chemistry. Coal reserves are enormous, about 1000 billions of tons (i.e. 250 years of consumption with the present day rate) but their exploitation will be in competition with less costly and less polluting energy sources. This documents treats of all aspects of coal: origin, composition, calorific value, classification, resources, reserves, production, international trade, sectoral consumption, cost, retail price, safety aspects of coal mining, environmental impacts (solid and gaseous effluents), different technologies of coal-fired power plants and their relative efficiency, alternative solutions for the recovery of coal energy (fuel cells, liquefaction). (J.S.)

  9. The CIS coal summit

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The presentations (overhead/viewgraphs) include: the impacts of EU environmental legislation on Russian coal market (A. Sankovski); how Caterpillar and Cat dealers create value in the global mining industry (D. Mohr); new coal preparation technology and application in the Russian coal market (D. Morris); UK demand outlook and import growth (G. Parker); new technologies in blasting operations and services (J. Petzold and others); a global bank's view of the coal sector (M. Seleznev); ELGA coal deposit, Republic of Sakha (Yakutia), Russia (M. Tsikanov); Russia's economic outlook (P. Forrest); Renaissance Capital (investment bank) (R. Edwards); Russian coal for Korean gencos (S. Kim); and coking coal in Ukraine (V. Khilko).

  10. High-Speed Turbulent Reacting Flows: Intrinsic Flame Instability and its Effects on the Turbulent Cascade

    Science.gov (United States)

    Poludnenko, Alexei

    2016-11-01

    Turbulent reacting flows are pervasive both in our daily lives on Earth and in the Universe. They power modern society being at the heart of many energy generation and propulsion systems, such as gas turbines, internal combustion and jet engines. On astronomical scales, thermonuclear turbulent flames are the driver of some of the most powerful explosions in the Universe, knows as Type Ia supernovae. Despite this ubiquity in Nature, turbulent reacting flows still pose a number of fundamental questions often exhibiting surprising and unexpected behavior. In this talk, we will discuss several such phenomena observed in direct numerical simulations of high-speed, premixed, turbulent flames. We show that turbulent flames in certain regimes are intrinsically unstable even in the absence of the surrounding combustor walls or obstacles, which can support the thermoacoustic feedback. Such instability can fundamentally change the structure and dynamics of the turbulent cascade, resulting in a significant (and anisotropic) redistribution of kinetic energy from small to large scales. In particular, three effects are observed. 1) The turbulent burning velocity can develop pulsations with significant peak-to-peak amplitudes. 2) Unstable burning can result in pressure build-up and the formation of pressure waves or shocks when the flame speed approaches or exceeds the speed of a Chapman-Jouguet deflagration. 3) Coupling of pressure and density gradients across the flame can lead to the anisotropic generation of turbulence inside the flame volume and flame acceleration. We extend our earlier analysis, which relied on a simplified single-step reaction model, by demonstrating existence of these effects in realistic chemical flames (hydrogen and methane) and in thermonuclear flames in degenerate, relativistic plasmas found in stellar interiors. Finally, we discuss the implications of these results for subgrid-scale LES combustion models. This work was supported by the Air Force

  11. Turbulence-flame interactions in DNS of a laboratory high Karlovitz premixed turbulent jet flame

    Science.gov (United States)

    Wang, Haiou; Hawkes, Evatt R.; Chen, Jacqueline H.

    2016-09-01

    In the present work, direct numerical simulation (DNS) of a laboratory premixed turbulent jet flame was performed to study turbulence-flame interactions. The turbulent flame features moderate Reynolds number and high Karlovitz number (Ka). The orientations of the flame normal vector n, the vorticity vector ω and the principal strain rate eigenvectors ei are examined. The in-plane and out-of-plane angles are introduced to quantify the vector orientations, which also measure the flame geometry and the vortical structures. A general observation is that the distributions of these angles are more isotropic downstream as the flame and the flow become more developed. The out-of-plane angle of the flame normal vector, β, is a key parameter in developing the correction of 2D measurements to estimate the corresponding 3D quantities. The DNS results show that the correction factor is unity at the inlet and approaches its theoretical value of an isotropic distribution downstream. The alignment characteristics of n, ω and ei, which reflect the interactions of turbulence and flame, are also studied. Similar to a passive scalar gradient in non-reacting flows, the flame normal has a tendency to align with the most compressive strain rate, e3, in the flame, indicating that turbulence contributes to the production of scalar gradient. The vorticity dynamics are examined via the vortex stretching term, which was found to be the predominant source of vorticity generation balanced by dissipation, in the enstrophy transport equation. It is found that although the vorticity preferentially aligns with the intermediate strain rate, e2, the contribution of the most extensive strain rate, e1, to vortex stretching is comparable with that of the intermediate strain rate, e2. This is because the eigenvalue of the most extensive strain rate, λ1, is always large and positive. It is confirmed that the vorticity vector is preferentially positioned along the flame tangential plane, contributing

  12. Structure of Flame Balls at Low Lewis-Number

    Science.gov (United States)

    Weiland, Karen J.; Ronney, Paul

    1998-01-01

    The Structure of Flame Balls at Low Lewis-Number (SOFBALL) experiment explored the behavior of a newly discovered flame phenomena called "flame balls." These spherical, stable, stationary flame structures, observed only in microgravity, provide a unique opportunity to study the interactions of the two most important processes necessary for combustion (chemical reaction and heat and mass transport) in the simplest possible configuration. The previously unobtainable experimental data provided a comparison with models of flame stability and flame propagation limits that are crucial both in assessing fire safety and in designing efficient, clean-burning combustion engines.

  13. Flame Quenching Dynamics of High Velocity Flames in Rectangular Cross-section Channels

    KAUST Repository

    Mahuthannan, Ariff Magdoom

    2017-01-05

    Understanding flame quenching for different conditions is necessary to develop safety devices like flame arrestors. In practical applications, the speed of a deflagration in the lab-fixed reference frame will be a strong function of the geometry through which the deflagration propagates. This study reports on the effect of the flame speed, at the entrance of a quenching section, on the quenching distance. A 2D rectangular channel joining two main spherical vessels is considered for studying this effect. Two different velocity regimes are investigated and referred to as configurations A, and B. For configuration A, the velocity of the flame is 20 m/s, while it is about 100 m/s for configuration B. Methane-air stoichiometric mixtures at 1 bar and 298 K are used. Simultaneous dynamic pressure measurements along with schlieren imaging are used to analyze the quenching of the flame. Risk assessment of re-ignition is also reported and analyzed.

  14. Engineering Flame Retardant Biodegradable Nanocomposites

    Science.gov (United States)

    He, Shan; Yang, Kai; Guo, Yichen; Zhang, Linxi; Pack, Seongchan; Davis, Rachel; Lewin, Menahem; Ade, Harald; Korach, Chad; Kashiwagi, Takashi; Rafailovich, Miriam

    2013-03-01

    Cellulose-based PLA/PBAT polymer blends can potentially be a promising class of biodegradable nanocomposites. Adding cellulose fiber reinforcement can improve mechanical properties of biodegradable plastics, but homogeneously dispersing hydrophilic cellulose in the hydrophobic polymer matrix poses a significant challenge. We here show that resorcinol diphenyl phosphates (RDP) can be used to modify the surface energy, not only reducing phase separation between two polymer kinds but also allowing the cellulose particles and the Halloysite clay to be easily dispersed within polymer matrices to achieve synergy effect using melt blending. Here in this study we describe the use of cellulose fiber and Halloysite clay, coated with RDP surfactant, in producing the flame retardant polymer blends of PBAT(Ecoflex) and PLA which can pass the stringent UL-94 V0 test. We also utilized FTIR, SEM and AFM nanoindentation to elucidate the role RDP plays in improving the compatibility of biodegradable polymers, and to determine structure property of chars that resulted in composites that could have optimized mechanical and thermal properties. Supported by Garcia Polymer Center and NSF Foundation.

  15. A, a Brominated Flame Retardant

    Directory of Open Access Journals (Sweden)

    Tomomi Takeshita

    2013-01-01

    Full Text Available Tetrabromobisphenol A (TBBPA, a brominated flame retardant, has been found to exacerbate pneumonia in respiratory syncytial virus- (RSV- infected mice. We examined the effect of Brazilian propolis (AF-08 on the exacerbation of RSV infection by TBBPA exposure in mice. Mice were fed a powdered diet mixed with 1% TBBPA alone, 0.02% AF-08 alone, or 1% TBBPA and 0.02% AF-08 for four weeks and then intranasally infected with RSV. TBBPA exposure increased the pulmonary virus titer and level of IFN-γ, a representative marker of pneumonia due to RSV infection, in the lungs of infected mice without toxicity. AF-08 was significantly effective in reducing the virus titers and IFN-γ level increased by TBBPA exposure. Also, AF-08 significantly reduced proinflammatory cytokine (TNF-α and IL-6 levels in the lungs of RSV-infected mice with TBBPA exposure, but Th2 cytokine (IL-4 and IL-10 levels were not evidently increased. Neither TBBPA exposure nor AF-08 treatment affected the anti-RSV antibody production in RSV-infected mice. In flow cytometry analysis, AF-08 seemed to be effective in reducing the ratio of pulmonary CD8a+ cells in RSV-infected mice with TBBPA exposure. TBBPA and AF-08 did not exhibit anti-RSV activity in vitro. Thus, AF-08 probably ameliorated pneumonia exacerbated by TBBPA exposure in RSV-infected mice by limiting excess cellular immune responses.

  16. Electromagnetic De-Shaling of Coal

    NARCIS (Netherlands)

    De Jong, T.P.R.; Mesina, M.B.; Kuilman, W.

    2003-01-01

    The efficiency with which an electromagnetic sensor array is able to distinguish density and ash content of coal and shale mixtures was determined experimentally. The investigated sensor was originally designed for automatic metal detection and sorting in industrial glass recycle processing, where i

  17. Characterization of single coal particle combustion within oxygen-enriched environments using high-speed OH-PLIF

    Science.gov (United States)

    Köser, J.; Becker, L. G.; Vorobiev, N.; Schiemann, M.; Scherer, V.; Böhm, B.; Dreizler, A.

    2015-12-01

    This work presents first-of-its-kind high-speed planar laser-induced fluorescence measurements of the hydroxyl radical in the boundary layer of single coal particles. Experiments were performed in a laminar flow reactor providing an oxygen-enriched exhaust gas environment at elevated temperatures. Single coal particles in a sieve fraction of 90-125 µm and a significant amount of volatiles (36 wt%) were injected along the burner's centerline. Coherent anti-Stokes Raman spectroscopy measurements were taken to characterize the gas-phase temperature. Time-resolved imaging of the OH distribution at 10 kHz allowed identifying reaction and post-flame zones and gave access to the temporal evolution of burning coal particles. During volatile combustion, a symmetric diffusion flame was observed around the particle starting from a distance of ~150 µm from the particle surface. For subsequent char combustion, this distance decreased and the highest OH signals appeared close to the particle surface.

  18. Effects of Surface Chemistry on the Porous Structure of Coal

    Energy Technology Data Exchange (ETDEWEB)

    Radovic, Ljubisa R; Hatcher, Patrick G

    1997-05-01

    In this report, 129 Xe nuclear magnetic resonance spectroscopy of xenon gas adsorbed in coal is used to describe some poorly understood features of coal microporous structure, particularly in establishing that a connected network exists, the type of connectivity, and its changes with the rank of coal. Micropore size scale and distribution are also considered. Two methods are developed which are new and versatile tools for the investigation of porous structure. Both utilize xenon gas that is in motion, while undergoing diffusion or exchange in coal, to describe the connectivity of the micropore structure of coal. Time tracking of the adsorption process by NMR, selective saturation, and saturation transfer techniques were used to obtain new information on the coal rank dependence of porous structure. In addition, an existing 129 Xe chemical shift-pore diameter model was used to calculate micropore diameters for coals, as well as for a microporous carbon, before and after pore-size alteration. In the initial study performed, straightforward 129 Xe NMR spectra at equilibrium xenon adsorption at a series of pressures were acquired for a rank-varied set of six coals. Acquisition of the NMR signal as an echo was tested and found to improve spectral quality. The spectra were used to calculate micropore diameters for the six coals. These range from 5.6 to 7.5 and exhibit a minimum value for the intermediate coal rank. The smallest pores occur in coals of about 82-85% carbon; at both lower and higher coal ranks, the average micropore size tends to be larger. The changes in the spectra with coal rank and surface area were explored. Signal linewidths were found to decrease with increasing coal rank and were interpreted in terms of increasing chemical or physical homogeneity of the coal as rank increases. The packing density of powdered coal was found to alter the spectral appearance in a high volatile bituminous coal, which is preliminary evidence that exchange affects the

  19. Nitrogen Injection To Flush Coal Seam Gas Out Of Coal: An Experimental Study

    Science.gov (United States)

    Zhang, Lei; Aziz, Naj; Ren, Ting; Nemcik, Jan; Tu, Shihao

    2015-12-01

    Several mines operating in the Bulli seam of the Sydney Basin in NSW, Australia are experiencing difficulties in reducing gas content within the available drainage lead time in various sections of the coal deposit. Increased density of drainage boreholes has proven to be ineffective, particularly in sections of the coal seam rich in CO2. Plus with the increasing worldwide concern on green house gas reduction and clean energy utilisation, significant attention is paid to develop a more practical and economical method of enhancing the gas recovery from coal seams. A technology based on N2 injection was proposed to flush the Coal Seam Gas (CSG) out of coal and enhance the gas drainage process. In this study, laboratory tests on CO2 and CH4 gas recovery from coal by N2 injection are described and results show that N2 flushing has a significant impact on the CO2 and CH4 desorption and removal from coal. During the flushing stage, it was found that N2 flushing plays a more effective role in reducing adsorbed CH4 than CO2. Comparatively, during the desorption stage, the study shows gas desorption after N2 flushing plays a more effective role in reducing adsorbed CO2 than CH4.

  20. Sooting turbulent jet flame: characterization and quantitative soot measurements

    Science.gov (United States)

    Köhler, M.; Geigle, K. P.; Meier, W.; Crosland, B. M.; Thomson, K. A.; Smallwood, G. J.

    2011-08-01

    Computational fluid dynamics (CFD) modelers require high-quality experimental data sets for validation of their numerical tools. Preferred features for numerical simulations of a sooting, turbulent test case flame are simplicity (no pilot flame), well-defined boundary conditions, and sufficient soot production. This paper proposes a non-premixed C2H4/air turbulent jet flame to fill this role and presents an extensive database for soot model validation. The sooting turbulent jet flame has a total visible flame length of approximately 400 mm and a fuel-jet Reynolds number of 10,000. The flame has a measured lift-off height of 26 mm which acts as a sensitive marker for CFD model validation, while this novel compiled experimental database of soot properties, temperature and velocity maps are useful for the validation of kinetic soot models and numerical flame simulations. Due to the relatively simple burner design which produces a flame with sufficient soot concentration while meeting modelers' needs with respect to boundary conditions and flame specifications as well as the present lack of a sooting "standard flame", this flame is suggested as a new reference turbulent sooting flame. The flame characterization presented here involved a variety of optical diagnostics including quantitative 2D laser-induced incandescence (2D-LII), shifted-vibrational coherent anti-Stokes Raman spectroscopy (SV-CARS), and particle image velocimetry (PIV). Producing an accurate and comprehensive characterization of a transient sooting flame was challenging and required optimization of these diagnostics. In this respect, we present the first simultaneous, instantaneous PIV, and LII measurements in a heavily sooting flame environment. Simultaneous soot and flow field measurements can provide new insights into the interaction between a turbulent vortex and flame chemistry, especially since soot structures in turbulent flames are known to be small and often treated in a statistical manner.

  1. Approximate-analytical study on thermal preparation and combustion of a coal particle

    Energy Technology Data Exchange (ETDEWEB)

    Salomatov, V.V. [SB RAS, Novosibirsk (Russian Federation). Inst. of Thermophysics; Enkhjargal, Kh. [Mongolian Univ. of Science and Technology, Ulaanbaatar (Mongolia)

    2013-07-01

    The main amount of heat and electricity in the world is produced with application of coal. Following development of power engineering plans application of low-grade coals, including those of new deposits (Salomatov VV, Nature conservation technologies at thermal and atomic power plants, Novosibirsk, NSTU, 2006). Massive Shive-Ovoos open-cast is among such low developed deposits of Mongolia. This deposit requires a set of investigations on thermal preparation and combustion of coal, aimed at extensive and efficient energy utilization. Calculation of flame combustion of coals is based on dependences, which determine the whole combustion process of separate coal particles. For particles of natural coals these processes include complex transformations of organic and mineral parts of coal matrix, heating, devolatization, ignition and burning of coke residue. Such detailed elaboration requires complex physical and mathematical simulation. Five successive stages of thermal preparation and combustion of a coal particle with initial humidity and ash content were distinguished by experimental results: 1. Heating. The particle is heated; the temperature increases, and the mass stays constant. 2. Drying. Liquid inside a wet particle evaporates and mass reduces. 3. Devolatization. 4. Ignition of slightly dried carbon layer by fuel gases. Residual moisture is still kept in the particle. 5. Burning. Two successive conditions are considered: 1. simultaneous burning of dried carbon layer and evaporation; 2. burning of absolutely dry coke residue.

  2. Correlation between coal characteristics and methane adsorption on China's coals

    Institute of Scientific and Technical Information of China (English)

    YU Hong-guan; YUAN Jian; SONG Ji-yong; LENG Shu-wei

    2007-01-01

    It is highly important to investigate relationship between coal characteristics and methane adsorption on coal in the fields of coalbed methane recovery. Based on data examination of coal quality indexes collected from the literatures, regression equations for Langmuir adsorption constants, VL or VL/PL, and coal quality indexes for selected coal samples were developed with multiple linear regression of SPSS software according to the degree of coal metamorphosis. The regression equations built were tested with data collected from some literatures, and the influences of coal quality indexes on CH4 adsorption on coals were studied with investigation of regression equations, and the reasons of low accuracy to Langmuir constants calculated with regression equation for a few coal samples were investigated. The results show that the regression equations can be employed to predict Langmuir constants for methane adsorption isotherms on coals obtained using volumetric gas adsorption experiments, which are conducted at 30 ℃ on a wet or dried coal samples with less than 30% ash content in coal. The influence of same coal quality index with various coal rank or influence of various coal quality indexes for same coal rank on CH4 adsorption is not consistent. The regression equations have different accuracy to different coal rank, in which the VL equations supply better prediction accuracy for anthracite and higher prediction error for lower metamorphosis coal, and the PL prediction error with VL and VL/PL equations is lower to bituminous coal and higher to anthracite.

  3. Launch Pad Flame Trench Refractory Materials

    Science.gov (United States)

    Calle, Luz M.; Hintze, Paul E.; Parlier, Christopher R.; Bucherl, Cori; Sampson, Jeffrey W.; Curran, Jerome P.; Kolody, Mark; Perusich, Steve; Whitten, Mary

    2010-01-01

    The launch complexes at NASA's John F. Kennedy Space Center (KSC) are critical support facilities for the successful launch of space-based vehicles. These facilities include a flame trench that bisects the pad at ground level. This trench includes a flame deflector system that consists of an inverted, V-shaped steel structure covered with a high temperature concrete material five inches thick that extends across the center of the flame trench. One side of the "V11 receives and deflects the flames from the orbiter main engines; the opposite side deflects the flames from the solid rocket boosters. There are also two movable deflectors at the top of the trench to provide additional protection to shuttle hardware from the solid rocket booster flames. These facilities are over 40 years old and are experiencing constant deterioration from launch heat/blast effects and environmental exposure. The refractory material currently used in launch pad flame deflectors has become susceptible to failure, resulting in large sections of the material breaking away from the steel base structure and creating high-speed projectiles during launch. These projectiles jeopardize the safety of the launch complex, crew, and vehicle. Post launch inspections have revealed that the number and frequency of repairs, as well as the area and size of the damage, is increasing with the number of launches. The Space Shuttle Program has accepted the extensive ground processing costs for post launch repair of damaged areas and investigations of future launch related failures for the remainder of the program. There currently are no long term solutions available for Constellation Program ground operations to address the poor performance and subsequent failures of the refractory materials. Over the last three years, significant liberation of refractory material in the flame trench and fire bricks along the adjacent trench walls following Space Shuttle launches have resulted in extensive investigations of

  4. Control of NO sub x emissions by combustion-air staging: the measurement of NH sub 3 , HCN, NO and N sub 2 O concentrations in fuel-oil flames

    Energy Technology Data Exchange (ETDEWEB)

    Nimmo, W.; Hampartsoumian, E.; Sedighi, K.; Williams, A. (Leeds Univ. (GB). Dept. of Fuel and Energy)

    1991-09-01

    The control of NO{sub x} formation from fuel-bound nitrogen in the combustion of coal and oil can give significant reductions in the final emission. One of the simplest and most cost-effective combustion modifications is that of staging the combustion air, whereby up to 50% is separated from the primary air and introduced into the flame further downstream. Thus the early part of the flame has a fuel-rich centre which provides a chemical environment that encourages the reaction of NO to form harmless products N{sub 2} and H{sub 2}O. The work presented here has investigated the in-flame development of NH{sub 3}, HCN, NO and N{sub 2}O for an unstaged and a staged (35%) oil flame, since they are the principal intermediates in the formation of NO. The oil spray was characterised by means of a laser particle-sizing technique over a range of oil pressures and combustion-air flows and two nozzle spray angles. The results were correlated with NO{sub x} emission measurements. The air-staging results showed that the virtually oxygen-free condition at the centre of the staged flame altered the ratio of HCN:NH{sub 3} significantly, and that in-flame development of NO was limited. Measurements of N{sub 2}O emissions from the unstaged and staged flames showed levels of typically less than 2 vpm in the exit flue, but the in-flame measurements showed that the unstaged flame exhibited a peak of circa 6 vpm at an axial position coincident with maximum NO concentrations. The staged flame did not display this feature. (author).

  5. Pretreatment of biomass by torrefaction and carbonization for coal blend used in pulverized coal injection.

    Science.gov (United States)

    Du, Shan-Wen; Chen, Wei-Hsin; Lucas, John A

    2014-06-01

    To evaluate the utility potential of pretreated biomass in blast furnaces, the fuel properties, including fuel ratio, ignition temperature, and burnout, of bamboo, oil palm, rice husk, sugarcane bagasse, and Madagascar almond undergoing torrefaction and carbonization in a rotary furnace are analyzed and compared to those of a high-volatile coal and a low-volatile one used in pulverized coal injection (PCI). The energy densities of bamboo and Madagascar almond are improved drastically from carbonization, whereas the increase in the calorific value of rice husk from the pretreatment is not obvious. Intensifying pretreatment extent significantly increases the fuel ratio and ignition temperature of biomass, but decreases burnout. The fuel properties of pretreated biomass materials are superior to those of the low-volatile coal. For biomass torrefied at 300°C or carbonized at temperatures below 500°C, the pretreated biomass can be blended with coals for PCI.

  6. Damköhler number effects on soot formation and growth in turbulent nonpremixed flames

    KAUST Repository

    Attili, Antonio

    2015-01-01

    The effect of Damköhler number on turbulent nonpremixed sooting flames is investigated via large scale direct numerical simulation in three-dimensional n-heptane/air jet flames at a jet Reynolds number of 15,000 and at three different Damköhler numbers. A reduced chemical mechanism, which includes the soot precursor naphthalene, and a high-order method of moments are employed. At the highest Damköhler number, local extinction is negligible, while flames holes are observed in the two lowest Damköhler number cases. Compared to temperature and other species controlled by fuel oxidation chemistry, naphthalene is found to be affected more significantly by the Damköhler number. Consequently, the overall soot mass fraction decreases by more than one order of magnitude for a fourfold decrease of the Damköhler number. On the contrary, the overall number density of soot particles is approximately the same, but its distribution in mixture fraction space is different in the three cases. The total soot mass growth rate is found to be proportional to the Damköhler number. In the two lowest Da number cases, soot leakage across the flame is observed. Leveraging Lagrangian statistics, it is concluded that soot leakage is due to patches of soot that cross the stoichiometric surface through flame holes. These results show the leading order effects of turbulent mixing in controlling the dynamics of soot in turbulent flames. © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

  7. Transition from pulled to pushed premixed turbulent flames due to countergradient transport

    Science.gov (United States)

    Sabelnikov, V. A.; Lipatnikov, A. N.

    2013-12-01

    The influence of countergradient transport on the speed of a statistically stationary, planar, 1D premixed flame that propagates in frozen turbulence is studied theoretically and numerically by considering the normalised magnitude NB of the countergradient flux to be an input parameter. Spectra of admissible flame speeds are analytically determined and explicit travelling wave solutions are found for two algebraic relations widely used to close the mean rate of product creation. A problem of selecting the physically relevant solution that is approached for sufficiently steep initial conditions is addressed. It is argued that, if NB is larger than an analytically determined critical number NcrB, then the type of the physically relevant solution is drastically changed. If NB pulled wave type, i.e. its speed is controlled by processes localised to the leading edge of the flame brush and can be determined within the framework of a linear analysis at the leading edge. If NB > NcrB, the physically relevant solution is of pushed wave type, i.e. its speed is controlled by processes in the entire flame brush. Analytical expressions for the speed of the physically relevant solution as a function of NB and the density ratio are obtained. For NB > NcrB, the mean flame brush thickness and the spatial profile of the Favre-averaged combustion progress variable are also determined analytically. These results are validated by numerical simulations. Both analytical expressions and numerical data indicate that (i) both turbulent flame speed and thickness are decreased when NB is increased and (ii) the direction of total scalar flux (i.e. the sum of countergradient and gradient contributions) is strongly affected not only by NB, but also by the shape of the dependence of the mean rate of product creation on the mean combustion progress variable.

  8. Chaotic radiation/turbulence interactions in flames

    Energy Technology Data Exchange (ETDEWEB)

    Menguec, M.P.; McDonough, J.M.

    1998-11-01

    In this paper, the authors present a review of their recent efforts to model chaotic radiation-turbulence interactions in flames. The main focus is to characterize soot volume fraction fluctuations in turbulent diffusion flames, as they strongly contribute to these interaction. The approach is based on the hypothesis that the fluctuations of properties in turbulent flames are deterministic in nature, rather than random. The authors first discuss the theoretical details and then they briefly outline the experiments conducted to measure the scattered light signals from fluctuating soot particles along the axis of an ethylene-air diffusion flame. They compare the power spectra and time series obtained from experiments against the ad-hoc and rigorous models derived using a series of logistic maps. These logistic maps can be used in simulation of the fluctuations in these type of flames, without extensive computational effort or sacrifice of physical detail. Availability of accurate models of these kinds allows investigation of radiation-turbulence interactions at a more fundamental level than it was previously possible.

  9. Aromatics oxidation and soot formation in flames

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T.

    1993-04-01

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify, and to confirm or determine rate constants for, the main benzene oxidation reactions in flames, and to characterize soot and fullerenes and their formation mechanisms and kinetics. Stable and radical species profiles in the aromatics oxidation study are measured using molecular beam sampling with on-line mass spectrometry. The rate of soot formation measured by conventional optical techniques is found to support the hypotheses that particle inception occurs through reactive coagulation of high molecular weight PAH in competition with destruction by OHattack, and that the subsequent growth of the soot mass occurs through addition reactions of PAH and C[sub 2]H[sub 2] with the soot particles. During the first year of this reporting period, fullerenes C[sub 60] and C[sub 70] in substantial quantities were found in the flames being studied. The fullerenes were recovered, purified and spectroscopically identified. The yields of C[sub 60] and C[sub 70] were then determined over ranges of conditions in low-pressure premixed flames of benzene and oxygen.

  10. Cellular burning in lean premixed turbulent hydrogen-air flames: Coupling experimental and computational analysis at the laboratory scale

    Science.gov (United States)

    Day, M. S.; Bell, J. B.; Cheng, R. K.; Tachibana, S.; Beckner, V. E.; Lijewski, M. J.

    2009-07-01

    One strategy for reducing US dependence on petroleum is to develop new combustion technologies for burning the fuel-lean mixtures of hydrogen or hydrogen-rich syngas fuels obtained from the gasification of coal and biomass. Fuel-flexible combustion systems based on lean premixed combustion have the potential for dramatically reducing pollutant emissions in transportation systems, heat and stationary power generation. However, lean premixed flames are highly susceptible to fluid-dynamical combustion instabilities making robust and reliable systems difficult to design. Low swirl burners are emerging as an important technology for meeting design requirements in terms of both reliability and emissions for next generation combustion devices. In this paper, we present simulations of a lean, premixed hydrogen flame stabilized on a laboratory-scale low swirl burner. The simulations use detailed chemistry and transport without incorporating explicit models for turbulence or turbulence/chemistry interaction. Here we discuss the overall structure of the flame and compare with experimental data. We also use the simulation data to elucidate the characteristics of the turbulent flame interaction and how this impacts the analysis of experimental measurements.

  11. Pulsating instability and self-acceleration of fast turbulent flames

    CERN Document Server

    Poludnenko, A Y

    2015-01-01

    (Abridged) A series of three-dimensional numerical simulations is used to study the intrinsic stability of high-speed turbulent flames. Calculations model the interaction of a fully-resolved premixed flame with a highly subsonic, statistically steady, homogeneous, isotropic turbulence. We consider a wide range of turbulent intensities and system sizes, corresponding to the Damk\\"ohler numbers Da = 0.1-6.0. These calculations show that turbulent flames in the regimes considered are intrinsically unstable. In particular, we find three effects. 1) Turbulent flame speed develops pulsations with the observed peak-to-peak amplitude > 10 and a characteristic time scale close to a large-scale eddy turnover time. Such variability is caused by the interplay between turbulence, which continuously creates the flame surface, and highly intermittent flame collisions, which consume the flame surface. 2) Unstable burning results in the periodic pressure build-up and the formation of pressure waves or shocks, when the flame s...

  12. Daphnid life cycle response to new generation of flame retardants

    NARCIS (Netherlands)

    Waaijers, S.L.; Bleyenberg, T.E.; Dits, A; Schoorl, M.; Schütt, J; Kools, S.A.E.; de Voogt, P.; Admiraal, W.; Parsons, J.R.; Kraak, M.H.S.

    2013-01-01

    Relatively hazardous brominated flame retardants (BFRs) are currently substituted with halogen-free flame retardants (HFFRs). Consequently, information on their persistence, bioaccumulation and toxicity (PBT) is urgently needed. Therefore, we investigated the chronic toxicity to the water flea

  13. Visualization of ionic wind in laminar jet flames

    KAUST Repository

    Park, Daegeun

    2017-07-03

    Electric field, when it is applied to hydrocarbon flames, generates ionic wind due to the electric body force on charge carrying species. Ionic wind has been shown to influence soot emission, propagation speed, and stability of flames; however, a detailed behavior of ionic wind and its effects on flames is still not clear. Here, we investigated the dynamic behaviors of flames and ionic wind in the presence of direct current (DC) and alternating current (AC) electric fields in nonpremixed and premixed jet flames with a jet nozzle placed between two parallel electrodes. We observed a skewed flame toward a lower potential electrode with DC and lower frequency AC (e.g., 10Hz) and a steady flame with higher frequencies AC (1000Hz), while we found that the ionic wind blew toward both the anode and cathode regardless of flame type (nonpremixed or premixed) or the source of the electric field (DC and AC).

  14. Thermal Decomposition Behavior and Kinetics of Composites from Coal and Polyethylene

    Institute of Scientific and Technical Information of China (English)

    YANG Fu-sheng; QU Jian-lin; YANG Zhi-yuan; ZHOU An-ning

    2007-01-01

    A thermogravimetric analysis (TG) was conducted to study the thermal decomposition behavior and kinetics of composites from coal and high density polyethylene (HDPE), linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). The results show that coal facilitates melting of the polyethylene before temperatures reach 700 K in nitrogen due to the exothermic effect of coal. Above 700 K, adding coal into the polyethylene will result in smaller maximum rates of mass loss and higher initial mass loss temperatures of the composites. Hence, some chemical interactions, occurring between liquid compounds released in the pyrolysis of the coal and polymer, depend on several factors, such as coal rank and the molecular structure of polymers. Synergetic effects in coal and polymers were also found. Both chemical interactions and synergetic effects control the entire thermal decomposition behavior of composites. The larger the amount of coal in the composites, the greater the decomposition temperature spans and the higher the maximum decomposition temperature, the smaller the devolatilization rates. The effect of coal on the thermal stability of composites lies in the hydrogen acceptor effect of the coals. Thermal decomposition of the coals, the polymers and related composites can be modelled via first order parallel reactions between 563 K and 763 K.

  15. Recycling of coal combustion wastes.

    Science.gov (United States)

    Oz, Derya; Koca, Sabina; Koca, Huseyin

    2009-05-01

    The separation of unburned carbon from coal-fired power plant bottom ashes was conducted in order to increase the possibility of the recycling of coal combustion wastes. A two-stage flotation technique was used for this study. In the rougher flotation experiments the amounts of collector, dispersant and frother, pulp density, pH, particle size distribution, flotation time and flotation temperature were tested as variables. After rougher flotation experiments, at optimum conditions, the carbon content of the concentrate increased from 13.85 to 51.54% at a carbon recovery of 54.54%. Under the same conditions, the carbon content was reduced to 4.54% at a weight yield of over 80% in the tailings fraction. This fraction meets the industrial specifications and can be utilized as a cement additive. After the cleaner flotation experiment the carbon content of the product was enhanced to 64.81% with a 52.16% carbon recovery. This fraction can be blended back into the coal feed to the power plant boilers.

  16. Fast Ignition and Stable Combustion of Coarse Coal Particles in a Nonslagging Cyclone Combustor

    Institute of Scientific and Technical Information of China (English)

    BiaoZhou; X.L.Wang; 等

    1995-01-01

    A combustion set-up of an innovative nonalagging cyclone combustor called “Spouting-Cyclone Combustor(SCC)”,,with two-stage combustion,organized in orthogonal vortex flows,was established and the experimental studies on the fast ignition and stable combustion of coarse coal particles in this combustor were carried out.The flame temperature versus ignition time and the practical fast ignition the temperature fields in SCC were obtained.These results whow that it is possible to obtain highly efficient and clean combustion of unground coal particles by using this technology.

  17. The Interaction of High-Speed Turbulence with Flames: Turbulent Flame Speed

    CERN Document Server

    Poludnenko, Alexei Y; 10.1016/j.combustflame.2010.09.002

    2011-01-01

    (Abridged) Direct numerical simulations of the interaction of a premixed flame with driven, subsonic, homogeneous, isotropic, Kolmogorov-type turbulence in an unconfined system are used to study the mechanisms determining the turbulent flame speed, S_T, in the thin reaction zone regime. High intensity turbulence is considered with the r.m.s. velocity 35 times the laminar flame speed, S_L, resulting in the Damkohler number Da = 0.05. Here we show that: (1) The flame brush has a complex internal structure, in which the isosurfaces of higher fuel mass fractions are folded on progressively smaller scales. (2) Global properties of the turbulent flame are best represented by the structure of the region of peak reaction rate, which defines the flame surface. (3) In the thin reaction zone regime, S_T is predominantly determined by the increase of the flame surface area, A_T, caused by turbulence. (4) The observed increase of S_T relative to S_L exceeds the corresponding increase of A_T relative to the surface area of...

  18. A Reduced Reaction Scheme for Volatile Nitrogen Conversion in Coal Combustion

    DEFF Research Database (Denmark)

    Pedersen, Lars Saaby; Glarborg, Peter; Dam-Johansen, Kim

    1998-01-01

    In pulverised coal flames, the most important volatile nitrogen component forming NOx is HCN. To be able to model the nitrogen chemistry in coal flames it is necessary to have an adequate model for HCN oxidation. The present work was concerned with developing a model for HCN/NH3/NO conversion based...... that the CO/H-2 chemistry was described adequately, the reduced HCN/NH3/NO model compared very well with the detailed model over a wide range of stoichiometries. Decoupling of the HCN chemistry from the CO/H-2 chemistry resulted in over-prediction of the HCN oxidation rate under fuel rich conditions, but had...... negligible effect on the CO/H-2 chemistry. Comparison with simplified HCN models from the literature revealed significant differences, indicating that these models should be used cautiously in modelling volatile nitrogen conversion....

  19. Modeling of Fine-Particle Formation in Turbulent Flames

    Science.gov (United States)

    Raman, Venkat; Fox, Rodney O.

    2016-01-01

    The generation of nanostructured particles in high-temperature flames is important both for the control of emissions from combustion devices and for the synthesis of high-value chemicals for a variety of applications. The physiochemical processes that lead to the production of fine particles in turbulent flames are highly sensitive to the flow physics and, in particular, the history of thermochemical compositions and turbulent features they encounter. Consequently, it is possible to change the characteristic size, structure, composition, and yield of the fine particles by altering the flow configuration. This review describes the complex multiscale interactions among turbulent fluid flow, gas-phase chemical reactions, and solid-phase particle evolution. The focus is on modeling the generation of soot particles, an unwanted pollutant from automobile and aircraft engines, as well as metal oxides, a class of high-value chemicals sought for specialized applications, including emissions control. Issues arising due to the numerical methods used to approximate the particle number density function, the modeling of turbulence-chemistry interactions, and model validation are also discussed.

  20. Coal, culture and community

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-11-01

    16 papers are presented with the following titles: the miners; municipalisation and the millenium - Bolton-upon-Dearne Urban District Council 1899-1914; the traditional working class community revisited; the cultural capital of coal mining communities; activities, strike-breakers and coal communities; the limits of protest - media coverage of the Orgreave picket during the miners` strike; in defence of home and hearth? Families, friendships and feminism in mining communities; young people`s attitudes to the police in mining communities; the determinants of productivity growth in the British coal mining industry, 1976-1989; strategic responses to flexibility - a case study in coal; no coal turned in Yorkshire?; the North-South divide in the Central Coalfields; the psychological effects of redundancy and worklessness - a case study from the coalfields; the Dearne Valley initiative; the future under labour: and coal, culture and the community.

  1. Beneficiated coals' char morphology

    Directory of Open Access Journals (Sweden)

    Diana Vargas

    2012-09-01

    Full Text Available This work evaluated the char morphology of beneficiated and original coal (without beneficiation from four Colombian coalmines: Cerrejón (La Guajira, La Jagua (Cesar, Guachinte (Valle del Cauca and Nechí (Antioquia. Column flotation was used to obtain beneficiated coal, whereas a drop tube reactor at 1,000°C, 104 °C/s heating rate and 100 ms residence time was used to obtain char. The chars were analysed by image analysis which determined their shape, size, porosity and wall thickness. It was found that char morphology depended on coal rank and maceral composition. Morphological characteristics like high porosity, thinner walls and network-like morphology which are beneficial in improving combustion were present in vitrinite- and liptinite-rich lowest-ranking coals. Beneficiated coals showed that their chars had better performance regarding their morphological characteristics than their original coal chars.

  2. Coal tar in dermatology

    Energy Technology Data Exchange (ETDEWEB)

    Roelofzen, J.H.J.; Aben, K.K.H.; Van Der Valk, P.G.M.; Van Houtum, J.L.M.; Van De Kerkhof, P.C.M.; Kiemeney, L.A.L.M. [Radboud University Nijmegen Medical Center, Nijmegen (Netherlands). Dept. of Dermatology

    2007-07-01

    Coal tar is one of the oldest treatments for psoriasis and eczema. It has anti-inflammatory, antibacterial, antipruritic and antimitotic effects. The short-term side effects are folliculitis, irritation and contact allergy. Coal tar contains carcinogens. The carcinogenicity of coal tar has been shown in animal studies and studies in occupational settings. There is no clear evidence of an increased risk of skin tumors or internal tumors. Until now, most studies have been fairly small and they did not investigate the risk of coal tar alone, but the risk of coal tar combined with other therapies. New, well-designed, epidemiological studies are necessary to assess the risk of skin tumors and other malignancies after dermatological use of coal tar.

  3. Coal: ditching the dirt

    Energy Technology Data Exchange (ETDEWEB)

    Russell, E.

    2006-01-01

    At the time when the British government is considering building new nuclear power plants, this article gives an overview of how the coal industry has been developing technologies to reduce greenhouse gas emissions and increase combustion efficiency which make coal a more attractive power source that should not be overlooked. Technologies mentioned include integrated gasification combined cycle, fluidized bed combustion, low NOx burners, and combustion control. Research is under way on capturing greenhouse gas emissions from fossil fuels. Use of fly ash in cement manufacture help reduce CO{sub 2} emissions. Clean coal technologies in the UK are supported by the IEA Clean Coal Centre, the World Coal Institute and the Coal Research Forum. 3 photos. 3 figs.

  4. Arthropod cuticles in coal

    Energy Technology Data Exchange (ETDEWEB)

    Bartram, K.M.; Jeram, A.J.; Selden, P.A.

    1987-05-01

    An abundance of scorpion cuticles from Westphalian (Upper Carboniferous) coals of Yorkshire is described, and other records of arthropod cuticles in coals are reviewed. The absence of cuticles assignable to arthropod groups other than scorpions is thought to be due to preferential preservation of the unique exocuticle of scorpions; it alone is preserved and appears to retain an organic nature. The cuticle is recovered from all the lithotypes of humic bituminous coals although it is most common in coals rich in inertinite macerals. From the present study it is uncertain whether the scorpions were aquatic or terrestrial. The recognition of arthropod cuticle as a coal maceral could aid environmental interpretations. The abundance of arthropod cuticle in the coals studied indicates its potential use in correlation and in determining the thermal maturity of sediments. 37 refs., 1 fig.

  5. CARS Temperature Measurements in Sooting, Laminar Diffusion Flames.

    Science.gov (United States)

    1984-07-30

    ethylene-air discussed above raise ques- tions about structure of a sooting flame and energy loss due to thermal radia- tion from soot. These questions do...certainly suggest that thermal radiation from soot may I, not be the only significant energy loss from a sooting flame . Nonluminous emission from CO2...CARS thermometry in a sooting flame . * Combust. Flame, 36, 87. Farrow, R. L., Lucht, R. P., Flower, W. L., and Palmer, R. E. (1984). Coherent anti

  6. Annealing effect and stability of carbon nanotubes in hydrogen flame

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Annealing of carbon nanotubes (CNTs) by the hydrogen flame in air was investigated in this study. Raman spectroscopy and scanning electron microscopy were used to characterize the products. The peak width of Raman spectra decreased with the increase in the annealing time. The CNTs were not stable in the hydrogen flame and the etching rate of the CNTs by hydrogen flame was very high. The hydrogen flame annealing had some effects on improving the crystallinity of CNTs.

  7. Cooperative research program in coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, G.P. (ed.)

    1991-01-01

    This Quarterly Report on coal liquefaction research includes discussion in the areas of (1) Iron Based Catalysts for Coal Liquefaction; (2) Exploratory Research on Coal Conversion; (3) Novel Coal Liquefaction Concepts; (4) Novel Catalysts for Coal Liquefaction. (VC)

  8. Cooperative research program in coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, G.P. (ed.)

    1992-01-01

    Research continues on coal liquefaction in the following areas: (1) Iron Based Catalysts for Coal Liquefaction; (2) Exploratory Research on Coal Conversion; (3) Novel Coal Liquefaction Concepts; (4) Novel Catalysts for Coal Liquefaction. (VC)

  9. Cooperative research program in coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, G.P. (ed.)

    1991-01-01

    This Quarterly Report on coal liquefaction research includes discussion in the areas of (1) Iron Based Catalysts for Coal Liquefaction; (2) Exploratory Research on Coal Conversion; (3) Novel Coal Liquefaction Concepts; (4) Novel Catalysts for Coal Liquefaction. (VC)

  10. The Influences of Electric Fields on Soot Formation and Flame Structure of Diffusion Flames

    Institute of Scientific and Technical Information of China (English)

    LinXie; TakeyukiKishi; 等

    1993-01-01

    The influences of DC and AC electric fields,at frequencies up to 1.48 MHz and the maximum strength of about 6 kV/cm,on soot formation and flame structure were investigated using a counterflow type acetylene diffusion flame.The distributioons of flame luminosity,soot volume fraction,Flame temperature and OH concentration in flame were measured by non-invasive detection methods.Under the influence of electric fields,the changes in distribution of the soot volume fraction were confirmed.Electric fields of high frequency and high intensity reduced the soot volume fraction.whereas other electric fields increased it.The maximum values of flame temperature and OH concentration decreased.In the relationship between the maximum value of the soot volume fraction and the maximum temperature,the maximum soot volum fraction showed toth increase and decrease with maximum temperatures depending on the frequencies and intensities of the electric fields,and both of them occurred at temperatures lower than 1990 K.The production of the incipient particles seemed to be the dominant process controlling the soot volume fraction due to the electric fields.The luminosity of a sooting diffusion flame was found to depend on the volume fraction and temperature of the soot particles in the flame,As for the behavior of the flame in the electric fields.the ionic wind effect was not found to be dominant in the present work,and the result of the precious simulation based on the ionic wind theory was not consistent with the present experimental results.

  11. The Flame Challenge and Communicating Science

    Science.gov (United States)

    Ames, Ben

    2013-04-01

    When famed actor and science enthusiast Alan Alda was 11 years-old he was itching to know the science behind a flame. He asked his science teacher but her blunt response didn't exactly satisfy his curiosity. ``It's oxidation,'' she said. 65 years later, Alan Alda launched ``The Flame Challenge,'' an annual contest encouraging scientists to improve their communication to the general public. In this talk, last year's winner discusses his approach to successfully explaining the science behind a flame to a wide audience. Because communicating science is a pillar of the scientific method, he shares key elements of successful communication important for engaging funders, policy-makers, students, the general public, and even other scientists.

  12. CO2 Sequestration Potential of Texas Low-Rank Coals

    Energy Technology Data Exchange (ETDEWEB)

    Duane A. McVay; Walter B. Ayers Jr; Jerry L. Jensen

    2003-07-01

    The objective of this project is to evaluate the feasibility of carbon dioxide (CO{sub 2}) sequestration in Texas low-rank coals and to determine the potential for enhanced coalbed methane (CBM) recovery as an added benefit of sequestration. The main objectives for this reporting period were to further characterize the three areas selected as potential test sites, to begin assessing regional attributes of natural coal fractures (cleats), which control coalbed permeability, and to interview laboratories for coal sample testing. An additional objective was to initiate discussions with an operating company that has interests in Texas coalbed gas production and CO{sub 2} sequestration potential, to determine their interest in participation and cost sharing in this project. Well-log data are critical for defining depth, thickness, number, and grouping of coal seams at the proposed sequestration sites. Therefore, we purchased 15 well logs from a commercial source to make coal-occurrence maps and cross sections. Log suites included gamma ray (GR), self potential (SP), resistivity, sonic, and density curves. Other properties of the coals in the selected areas were collected from published literature. To assess cleat properties and describe coal characteristics, we made field trips to a Jackson coal outcrop and visited Wilcox coal exposures at the Sandow surface mine. Coal samples at the Sandow mine were collected for CO{sub 2} and methane sorption analyses. We contacted several laboratories that specialize in analyzing coals and selected a laboratory, submitting the Sandow Wilcox coals for analysis. To address the issue of cost sharing, we had fruitful initial discussions with a petroleum corporation in Houston. We reviewed the objectives and status of this project, discussed data that they have already collected, and explored the potential for cooperative data acquisition and exchange in the future. We are pursuing a cooperative agreement with them.

  13. CLEANER ENERGY FROM COAL

    Directory of Open Access Journals (Sweden)

    Adina-MilenaTĂTAR

    2016-12-01

    Full Text Available With the ever-increasing demand for coal, particularly in the developing world, the use of low emission coal technologies becomes increasingly important if international targets on climate change are to be achieved. The two principal avenues for reducing carbon emissions from coal-fired power generation are through use of high efficiency, low emission power plantsand carbon capture, use and storage.

  14. Supercritical solvent coal extraction

    Science.gov (United States)

    Compton, L. E. (Inventor)

    1984-01-01

    Yields of soluble organic extract are increased up to about 50% by the supercritical extraction of particulate coal at a temperature below the polymerization temperature for coal extract fragments (450 C.) and a pressure from 500 psig to 5,000 psig by the conjoint use of a solvent mixture containing a low volatility, high critical temperature coal dissolution catalyst such as phenanthrene and a high volatility, low critical temperature solvent such as toluene.

  15. Biodesulfurization of Malaysian coals using mixed microbial cultures in batch and continuous processes

    Energy Technology Data Exchange (ETDEWEB)

    Najafpour, G.D.; Azizan, A.; Harun, A. [Universiti Sains Malaysia, Darul Ridzuan (Malaysia). School of Chemical Engineering

    2001-07-01

    The determination of chemolithotrophic microorganisms capable to grown on coal with high sulfur content, made it possible to develop mixed culture processes for coal desulfurization. The ability of the microbial cultures to metabolize different sulfur compounds originated from coal in the range of 3-5% sulfur, were demonstrated in batch experimental stage. Biodesulfurization of coal as suspended solid coal particles were carried out in a broth media for coal content of 1-5% solid. Four species of microbial culture were grown on coal and acclimated for optimal growth. The coal samples obtained from Malaysian coal mine with 2-5% of sulfur content were used in batch and continuous cultures experiments. The microbial cultures were used to reduce pyrite sulfur, inorganic sulfur content of coal. The culture isolated from pharmaceutical wastewater shown that more than 80% of sulfur content of coal was reduced. The growth of microorganisms on coal shown that maximum solid content of 5% was tolerable maximum grow on 3% coal shown high cell density. Nutrient media with acidic PH value of 3-4 was required for growth of Thiobacillus thiooxidans and Thiobacillus fierrooxidans. The growth was limited at PH = 2 but at PH 3-4 growth was stimulated. Phosphate buffer was used with coal solution to monitor the PH. The PH was initially adjusted but was not controlled during the period of incubation. An optimum PH for Thiobacillus species with maximum desulfuriation was 2.65. High coal content about 10% was shown that bacterial was unable to grow. The cell dry weight, cell optical density and sulfur content of coal samples using TGA and elemental analyzer were conducted for all experiments. 10 refs., 11 figs.

  16. Front roughening of flames in discrete media

    Science.gov (United States)

    Lam, Fredric; Mi, XiaoCheng; Higgins, Andrew J.

    2017-07-01

    The morphology of flame fronts propagating in reactive systems composed of randomly positioned, pointlike sources is studied. The solution of the temperature field and the initiation of new sources is implemented using the superposition of the Green's function for the diffusion equation, eliminating the need to use finite-difference approximations. The heat released from triggered sources diffuses outward from each source, activating new sources and enabling a mechanism of flame propagation. Systems of 40 000 sources in a 200 ×200 two-dimensional domain were tracked using computer simulations, and statistical ensembles of 120 realizations of each system were averaged to determine the statistical properties of the flame fronts. The reactive system of sources is parameterized by two nondimensional values: the heat release time (normalized by interparticle diffusion time) and the ignition temperature (normalized by adiabatic flame temperature). These two parameters were systematically varied for different simulations to investigate their influence on front propagation. For sufficiently fast heat release and low ignition temperature, the front roughness [defined as the root mean square deviation of the ignition temperature contour from the average flame position] grew following a power-law dependence that was in excellent agreement with the Kardar-Parisi-Zhang (KPZ) universality class (β =1 /3 ). As the reaction time was increased, lower values of the roughening exponent were observed, and at a sufficiently great value of reaction time, reversion to a steady, constant-width thermal flame was observed that matched the solution from classical combustion theory. Deviation away from KPZ scaling was also observed as the ignition temperature was increased. The features of this system that permit it to exhibit both KPZ and non-KPZ scaling are discussed.

  17. Large Scale Flame Spread Environmental Characterization Testing

    Science.gov (United States)

    Clayman, Lauren K.; Olson, Sandra L.; Gokoghi, Suleyman A.; Brooker, John E.; Ferkul, Paul V.; Kacher, Henry F.

    2013-01-01

    Under the Advanced Exploration Systems (AES) Spacecraft Fire Safety Demonstration Project (SFSDP), as a risk mitigation activity in support of the development of a large-scale fire demonstration experiment in microgravity, flame-spread tests were conducted in normal gravity on thin, cellulose-based fuels in a sealed chamber. The primary objective of the tests was to measure pressure rise in a chamber as sample material, burning direction (upward/downward), total heat release, heat release rate, and heat loss mechanisms were varied between tests. A Design of Experiments (DOE) method was imposed to produce an array of tests from a fixed set of constraints and a coupled response model was developed. Supplementary tests were run without experimental design to additionally vary select parameters such as initial chamber pressure. The starting chamber pressure for each test was set below atmospheric to prevent chamber overpressure. Bottom ignition, or upward propagating burns, produced rapid acceleratory turbulent flame spread. Pressure rise in the chamber increases as the amount of fuel burned increases mainly because of the larger amount of heat generation and, to a much smaller extent, due to the increase in gaseous number of moles. Top ignition, or downward propagating burns, produced a steady flame spread with a very small flat flame across the burning edge. Steady-state pressure is achieved during downward flame spread as the pressure rises and plateaus. This indicates that the heat generation by the flame matches the heat loss to surroundings during the longer, slower downward burns. One heat loss mechanism included mounting a heat exchanger directly above the burning sample in the path of the plume to act as a heat sink and more efficiently dissipate the heat due to the combustion event. This proved an effective means for chamber overpressure mitigation for those tests producing the most total heat release and thusly was determined to be a feasible mitigation

  18. Preparation and characterizations of flame retardant polyamide 66 fiber

    Science.gov (United States)

    Li, Y. Y.; Liu, K.; Xiao, R.

    2017-06-01

    The polyamide 66 (PA66) is one of the most important thermoplastic materials, but it has the drawback of flammability. So the flame retardant PA66 was prepared by condensation polymerization using nylon salt and DOPO-based flame retardant in this paper. Then the flame retardant PA66 fiber was manufactured via melt spinning. The properties of flame retardant PA66 and flame retardant PA66 fiber were investigated by relative viscosity, differential scanning calorimetry (DSC), tensile test, vertical burning test (UL94) and limiting oxygen index (LOI) test. Although the loading of the DOPO-based flame retardant decreased the molecular weight, the melting temperature, the crystallinity and the mechanical properties of flame retardant PA66, the flame retardancy properties improved. The flame retardant PA66 loaded with 5.5 wt% of DOPO-based flame retardant can achieve a UL94 V-0 rating with a LOI value of 32.9%. The tenacity at break decreased from 4.51 cN·dtex-1 for PA66 fiber to 2.82 cN·dtex-1 for flame retardant PA66 fiber which still satisfied the requirements for fabrics. The flame retardant PA66 fiber expanded the application of PA66 materials which had a broad developing prospect.

  19. 30 CFR 56.6904 - Smoking and open flames.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Smoking and open flames. 56.6904 Section 56.6904 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Requirements § 56.6904 Smoking and open flames. Smoking and use of open flames shall not be permitted within...

  20. Entrainment regimes and flame characteristics of wildland fires

    Science.gov (United States)

    Ralph M. Nelson; Bret W. Butler; David R. Weise

    2012-01-01

    This paper reports results from a study of the flame characteristics of 22 wind-aided pine litter fires in a laboratory wind tunnel and 32 field fires in southern rough and litter-grass fuels. Flame characteristic and fire behaviour data from these fires, simple theoretical flame models and regression techniques are used to determine whether the data support the...

  1. Pyrolysis of Coal

    Directory of Open Access Journals (Sweden)

    Rađenović, A.

    2006-07-01

    Full Text Available The paper presents a review of relevant literature on coal pyrolysis.Pyrolysis, as a process technology, has received considerable attention from many researchers because it is an important intermediate stage in coal conversion.Reactions parameters as the temperature, pressure, coal particle size, heating rate, soak time, type of reactor, etc. determine the total carbon conversion and the transport of volatiles and therebythe product distribution. Part of the possible environmental pollutants could be removed by optimising the pyrolysis conditions. Therefore, this process will be subsequently interesting for coal utilization in the future

  2. Petrographers fingerprint coals

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, D.E. [Pearson and Associates Ltd. (USA)

    2001-05-01

    A new system of coal fingerprinting called Digipet generates reflectance profiles by using an automated digital imaging system in which tens of millions of individual reflectance measurements are obtained. Images are conditioned to generate a detailed smooth histogram which convey information on the coal sample's provenance and history. Expert interpretation can reveal further information. The article gives details of the instrument and shows sample reflectance profiles. It discusses some applications in sampling coal charged to coke ovens of the Indiana Harbor Coke Co, and at a Midwest generating plant where it detected the presence of rogue high volatile coal. 3 figs.

  3. Combustion of dense streams of coal particles. Final report, August 29, 1990--February 28, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Annamalai, K.; Gopalakrishnan, C.; Du, X.

    1994-05-01

    The USA consumes almost 94 quads of energy (1 quad = 10{sup 15} BTU or 1.05 {times} 10{sup 15} KJ). The utilities account for about 30 quads of fossil energy where coal is predominantly used as energy source. The coal is ground to finer size and fired into the boiler as dense suspension. Under dense conditions, the particles burn at slower rate due to deficient oxygen within the interparticle spacing. Thus interactions exist amongst the particles for dense clouds. While the earlier literature dealt with combustion processes of isolated particles, the recent research focusses upon the interactive combustion. The interactive combustion studies include arrays consisting of a finite number of particles, and streams and clouds of a large number of particles. Particularly stream combustion models assume cylindrical geometry and predict the ignition and combustion characteristics. The models show that the ignition starts homogeneously for dense streams of coal particles and the ignition time show a minimum as the stream denseness is increased, and during combustion, there appears to be an inner flame within the stream and an outer flame outside the stream for a short period of time. The present experimental investigation is an attempt to verify the model predictions. The set-up consists of a flat flame burner for producing hot vitiated gases, a locally fluidizing feeder system for feeding coal particles, a particle collection probe for collecting particles and an image processing system for analyzing the flame structure. The particles are introduced as a stream into the hot gases and subsequently they ignite and burn. The ash % of fired and collected particles are determined and used to estimate the gasification efficiency or burnt fraction. The parametric studies include gas temperature, oxygen % in gases, residence time, and A:F ratio of the stream.

  4. OxyFuel combustion of Coal and Biomass

    DEFF Research Database (Denmark)

    Toftegaard, Maja Bøg

    of coal and straw at conditions relevant to suspension-fired boilers by clarifying the effect of the change in combustion atmosphere on fuel burnout, flame temperatures, emissions of polluting species (NO, SO2, and CO), fly ash quality, and deposit formation. This work is one of the first to investigate...... and oxyfuel atmospheres. Apart from slightly improved burnout and reduced emissions of NO during oxyfuel combustion these operating conditions yield similar combustion characteristics in both environments. Co-firing coal and biomass or combustion of pure biomass in an oxyfuel power plant could yield...... be adjusted independently. By increasing the concentration of oxygen in the oxidant, i.e. by reducing the flue gas recirculation ratio, it is possible to achieve similar burnout at lower oxygen excess levels. Further work on implications of this strategy are necessary in order to fully clarify its potential...

  5. Flame-Vortex Interactions Imaged in Microgravity - To Assess the Theory Flame Stretch

    Science.gov (United States)

    Driscoll, James F.

    2001-01-01

    The goals of this research are to: 1) Assess the Theory of Flame Stretch by operating a unique flame-vortex experiment under microgravity conditions in the NASA Glenn 2.2 Second Drop Tower (drops to identify operating conditions have been completed); 2) Obtain high speed shadowgraph images (500-1000 frames/s) using the drop rig (images were obtained at one-g, and the NASA Kodak RO camera is being mounted on the drop rig); 3) Obtain shadowgraph and PIV images at 1-g while varying the effects of buoyancy by controlling the Froude number (completed); 4) Numerically model the inwardly-propagating spherical flame that is observed in the experiment using full chemistry and the RUN 1DL code (completed); 5) Send images of the flame shape to Dr. G. Patniak at NRL who is numerically simulating the entire flame-vortex interaction of the present experiment (data transfer completed); and 6) Assess the feasibility of obtaining PIV velocity field images in the drop rig, which would be useful (but not required) for our assessment of the Theory of Flame Stretch (PIV images were obtained at one-g using same low laser power that is available from fiber optic cable in drop tower). The motivation for the work is to obtain novel measurement needed to develop a physically accurate model of turbulent combustion that can help in the control of engine pollutants. The unique experiment allows, for the first time, the detailed study of a negatively-curved (negatively stretched) flame, which is one of the five fundamental types of premixed flames. While there have been studies of flat flames, positively-curved (outwardly-propagating) cases and positively-strained (counterflow) cases, this is the first detailed study of a negatively-curved (inwardly-propagating) flame. The first set of drops in the 2.2 Second Drop Tower showed that microgravity provides more favorable conditions for achieving inwardly-propagating flames (IPFs) than 1-g. A vortex interacts with a flame and creates a spherical

  6. Computatonal and experimental study of laminar flames

    Energy Technology Data Exchange (ETDEWEB)

    Smooke, M.D.; Long, M.B. [Yale Univ., New Haven, CT (United States)

    1993-12-01

    This research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in counterflow, cylindrical and coflowing axisymmetric configurations. The authors have pursued both computational and experimental aspects of the research in parallel. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the one and two-dimensional nonlinear boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. In particular, spontaneous Raman scattering and laser induced fluorescence were used to measure the temperature, major and minor species profiles.

  7. Clean coal technologies market potential

    Energy Technology Data Exchange (ETDEWEB)

    Drazga, B. (ed.)

    2007-01-30

    Looking at the growing popularity of these technologies and of this industry, the report presents an in-depth analysis of all the various technologies involved in cleaning coal and protecting the environment. It analyzes upcoming and present day technologies such as gasification, combustion, and others. It looks at the various technological aspects, economic aspects, and the various programs involved in promoting these emerging green technologies. Contents: Industry background; What is coal?; Historical background of coal; Composition of coal; Types of coal; Environmental effects of coal; Managing wastes from coal; Introduction to clean coal; What is clean coal?; Byproducts of clean coal; Uses of clean coal; Support and opposition; Price of clean coal; Examining clean coal technologies; Coal washing; Advanced pollution control systems; Advanced power generating systems; Pulverized coal combustion (PCC); Carbon capture and storage; Capture and separation of carbon dioxide; Storage and sequestration of carbon dioxide; Economics and research and development; Industry initiatives; Clean Coal Power Initiative; Clean Coal Technology Program; Coal21; Outlook; Case Studies.

  8. Oxygen-Fired CO{sub 2} Recycle for Application to Direct CO{sub 2} Capture form Coal-Fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Thomas Gale

    2010-09-26

    The Southern Research/Southern Company 1 MWth Pilot-Scale Coal-Fired Test Facility was successfully retrofit to fire in either the traditional air-fired mode or with 100% oxygen and recycled flue gas, with a fully integrated feedback and control system, including oxygen and recycled flue gas modulation during startup, transfer, and shutdown, safety and operational interlocks, and data acquisition. A MAXON Staged Oxygen Burner for Oxy-Coal Applications produced a stable flame over a significant range of firing turn-down, staging, and while firing five different U.S. coal types. The MAXON burner design produces lower flame temperatures than for air firing, which will enable (A) Safe operation, (B) Reduction of recycle flow without concern about furnace flame temperatures, and (C) May likely be affective at reducing slagging and fouling in the boiler and super heater at full-scale Power Plants. A CFD model of the Oxy-fired Combustion Research Facility (OCRF) was used to predict the flame geometry and temperatures in the OCRF and make a comparison with the air-fired case. The model predictions were consistent with the experimental data in showing that the MAXON burner fired with oxygen produced lower flame temperatures than the air-fired burner while firing with air.

  9. Resolvent methods for steady premixed flame shapes governed by the Zhdanov-Trubnikov equation

    CERN Document Server

    Borot, Gaëtan; Joulin, Guy

    2012-01-01

    Using pole decompositions as starting points, the one parameter (-1 =< c < 1) nonlocal and nonlinear Zhdanov-Trubnikov (ZT) equation for the steady shapes of premixed gaseous flames is studied in the large-wrinkle limit. The singular integral equations for pole densities are closely related to those satisfied by the spectral density in the so-called O(n) matrix model, with n = -2(1 + c)/(1 - c). They can be solved via the introduction of complex resolvents and the use of complex analysis. We retrieve results obtained recently for -1 =< c =< 0, and we explain and cure their pathologies when they are continued naively to 0 < c < 1. Moreover, for any -1 =< c < 1, we derive closed-form expressions for the shapes of steady isolated flame crests, and then bicoalesced periodic fronts. These theoretical results fully agree with numerical resolutions. Open problems are evoked.

  10. Propellant Formulation Development for Future Army Weapons Systems By Means of Advanced Modeling and Flame Kinetics Research

    Science.gov (United States)

    2008-12-01

    PHASE FLAME • Elementary reactions • Thermal conduction • Convection • Molecular diffusion • Multi-component transport • Thermal diffusion LIQUID/FOAM...C-phase reactions • Thermal density changes • Mixture properties • Thermal conduction • Convection • Molecular diffusion • Bubble formation

  11. Compatibility of novel blends from polyolefin and coal

    Institute of Scientific and Technical Information of China (English)

    YANG Fu-sheng(杨伏生); ZHOU An-ning(周安宁)

    2004-01-01

    Melt blends of low-density polyethylene(LDPE), ethylene vinyl acetate(EVA) and coal with various compositions were prepared through reactive extrusion. The rheological behaviour was studied with respect to the effect of blend ratio, shear rate using a rheometer to gain an understanding of processing parameters controlling industrial application. Compatibility was also evaluated by differential scanning calorimetry(DSC) and scanning electron microscopy(SEM). The results revealed that LDPE/EVA/coal is a partly compatible system showing pseudo-plastic behaviour, increase in viscosity with increased coal content appeares evident only at low shear rate region, viscosity tends to keep consistent approximately but irrelates to coal content at higher shear rate. Blends viscosity and compatibility are attibuted to changes in LDPE crystalline structure and entanglement, together with interaction between macromolecular aliphatic chains in coal and amorphous phase in LDPE and EVA at the boundaries of phases, which comes forth during the rearrangement process of the crystalline structure.

  12. Large Eddy Simulation of an Oscillating Flame in Turbulent Flow Around a Bluff Body

    Science.gov (United States)

    2014-09-19

    different measurement techniques for determining the heat release rate are the detection of chemiluminescence from chemically excited hydroxyl radical ...the OH flu- orescence, namely the Flame Surface Density (FSD). An additional measure being relevant in this report is the mass fraction of formyl ... radical , HCO. In turbulent flows the mass fraction of HCO is experimentally de- termined through estimating the forward reaction rate of the reaction

  13. Ensuring slagging-free operation of a boiler equipped with hammer mills in firing brown coal with low-melting ash

    Science.gov (United States)

    Arkhipov, A. M.; Dorogoi, G. A.

    2011-04-01

    The possibility of ensuring slagging-free operation of heating surfaces in firing Pereyaslov brown coal is considered taking the PK-38 boiler at the Krasnoyarsk GRES-2 district power station as an example. Retrofitting of burners and nozzles and setting up of a recirculation-vortex flame are recommended.

  14. A simulation of a bluff-body stabilized turbulent premixed flame using LES-PDF

    Science.gov (United States)

    Kim, Jeonglae; Pope, Stephen

    2013-11-01

    A turbulent premixed flame stabilized by a triangular cylinder as a flame-holder is simulated. The computational condition matches the Volvo experiments (Sjunnesson et al. 1992). Propane is premixed at a fuel lean condition of ϕ = 0 . 65 . For this reactive simulation, LES-PDF formulation is used, similar to Yang et al. (2012). The evolution of Lagrangian particles is simulated by solving stochastic differential equations modeling transport of the composition PDF. Mixing is modeled by the modified IEM model (Viswanathan et al. 2011). Chemical reactions are calculated by ISAT and for the good load balancing, PURAN distribution of ISAT tables is applied (Hiremath et al. 2012). To calculate resolved density, the two-way coupling (Popov & Pope 2013) is applied, solving a transport equation of resolved specific volume to reduce statistical noise. A baseline calculation shows a good agreement with the experimental measurements in turbulence statistics, temperature, and minor species mass fractions. Chemical reaction does not significantly contribute to the overall computational cost, in contrast to non-premixed flame simulations (Hiremath et al. 2013), presumably due to the restricted manifold of the purely premixed flame in the composition space.

  15. Combined Influence of Strain and Heat Loss on Turbulent Premixed Flame Stabilization

    KAUST Repository

    Tay-Wo-Chong, Luis

    2015-11-16

    The present paper argues that the prediction of turbulent premixed flames under non-adiabatic conditions can be improved by considering the combined effects of strain and heat loss on reaction rates. The effect of strain in the presence of heat loss on the consumption speed of laminar premixed flames was quantified by calculations of asymmetric counterflow configurations (“fresh-to-burnt”) with detailed chemistry. Heat losses were introduced by setting the temperature of the incoming stream of products on the “burnt” side to values below those corresponding to adiabatic conditions. The consumption speed decreased in a roughly exponential manner with increasing strain rate, and this tendency became more pronounced in the presence of heat losses. An empirical relation in terms of Markstein number, Karlovitz Number and a non-dimensional heat loss parameter was proposed for the combined influence of strain and heat losses on the consumption speed. Combining this empirical relation with a presumed probability density function for strain in turbulent flows, an attenuation factor that accounts for the effect of strain and heat loss on the reaction rate in turbulent flows was deduced and implemented into a turbulent combustion model. URANS simulations of a premixed swirl burner were carried out and validated against flow field and OH chemiluminescence measurements. Introducing the effects of strain and heat loss into the combustion model, the flame topology observed experimentally was correctly reproduced, with good agreement between experiment and simulation for flow field and flame length.

  16. Flow Topology of Three-Dimensional Spherical Flame in Shock Accelerated Flows

    Directory of Open Access Journals (Sweden)

    Yuejin Zhu

    2016-01-01

    Full Text Available The flow topologies of compressible large-scale distorted flames are studied by means of the analysis of the invariants of the velocity gradient tensor (VGT. The results indicate that compressibility plays a minor role in the distorted flame zone. And the joint probability density function (p.d.f. of the Q-R diagram appears as a teardrop shape, which is a universal feature of turbulence. Therefore, the distorted flame exhibits the characteristic of large-scale turbulence combustion, especially behind the reflected shock wave, while the p.d.f. of the QS⁎-QW diagram implies that the dissipation is enhanced in the compression and expansion regions, where it is higher than that when P=0. Furthermore, we identify that the flame evolution is dominated by rotation by means of a quantitative statistical study, and the SFS topology is the predominant flow pattern. Not surprisingly, negative dilatation could suppress the unstable topologies, whereas positive dilatation could suppress the stable topologies.

  17. Radiative Structures of Lycopodium-Air Flames in Low Gravity

    Science.gov (United States)

    Berlad, A. L.; Tangirala, V.; Ross, H.; Facca, L.

    1989-01-01

    Initially uniform clouds of fuel particulates in air sustain processes which may lead to particle cloud nonuniformities. In low gravity, flame-induced Kundt's Tube phenomena are observed to form regular patterns of nonuniform particle concentrations. Irregular patterns of particle concentrations also are observed to result from selected nonuniform mixing processes. Low gravity flame propagation for each of these classes of particle cloud flames has been found to depend importantly on the flame-generated infrared radiative fields. The spatial structures of these radiative fields are described. Application is made for the observed clases of lycopodium-air flames.

  18. SURFACE-MODIFIED COALS FOR ENHANCED CATALYST DISPERSION AND LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Yaw D. Yeboah

    1999-09-01

    This is the final report of the Department of Energy Sponsored project DE-FGF22-95PC95229 entitled, surface modified coals for enhanced catalyst dispersion and liquefaction. The aims of the study were to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on the coal and to train and educate minority scientists in catalysts and separation science. Illinois No. 6 Coal (DEC-24) was selected for the study. The surfactants investigated included dodecyl dimethyl ethyl ammonium bromide (DDAB), a cationic surfactant, sodium dodecyl sulfate, an anionic surfactant, and Triton x-100, a neutral surfactant. Ammonium molybdate tetrahydrate was used as the molybdenum catalyst precursor. Zeta potential, BET, FTIR, AFM, UV-Vis and luminescence intensity measurements were undertaken to assess the surface properties and the liquefaction activities of the coal. The parent coal had a net negative surface charge over the pH range 2-12. However, in the presence of DDAB the negativity of the surface charge decreased. At higher concentrations of DDAB, a positive surface charge resulted. In contrast to the effect of DDAB, the zeta potential of the coal became more negative than the parent coal in the presence of SDS. Adsorption of Triton reduced the net negative charge density of the coal samples. The measured surface area of the coal surface was about 30 m{sup 2}/g compared to 77m{sup 2}/g after being washed with deionized water. Addition of the surfactants decreased the surface area of the samples. Adsorption of the molybdenum catalyst increased the surface area of the coal sample. The adsorption of molybdenum on the coal was significantly promoted by preadsorption of DDAB and SDS. Molybdenum adsorption showed that, over a wide range of concentrations and pH values, the DDAB treated coal adsorbed a higher amount of molybdenum than the samples treated with SDS. The infrared spectroscopy (FTIR) and the atomic force

  19. SURFACE-MODIFIED COALS FOR ENHANCED CATALYST DISPERSION AND LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Yaw D. Yeboah

    1999-09-01

    This is the final report of the Department of Energy Sponsored project DE-FGF22-95PC95229 entitled, surface modified coals for enhanced catalyst dispersion and liquefaction. The aims of the study were to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on the coal and to train and educate minority scientists in catalysts and separation science. Illinois No. 6 Coal (DEC-24) was selected for the study. The surfactants investigated included dodecyl dimethyl ethyl ammonium bromide (DDAB), a cationic surfactant, sodium dodecyl sulfate, an anionic surfactant, and Triton x-100, a neutral surfactant. Ammonium molybdate tetrahydrate was used as the molybdenum catalyst precursor. Zeta potential, BET, FTIR, AFM, UV-Vis and luminescence intensity measurements were undertaken to assess the surface properties and the liquefaction activities of the coal. The parent coal had a net negative surface charge over the pH range 2-12. However, in the presence of DDAB the negativity of the surface charge decreased. At higher concentrations of DDAB, a positive surface charge resulted. In contrast to the effect of DDAB, the zeta potential of the coal became more negative than the parent coal in the presence of SDS. Adsorption of Triton reduced the net negative charge density of the coal samples. The measured surface area of the coal surface was about 30 m{sup 2}/g compared to 77m{sup 2}/g after being washed with deionized water. Addition of the surfactants decreased the surface area of the samples. Adsorption of the molybdenum catalyst increased the surface area of the coal sample. The adsorption of molybdenum on the coal was significantly promoted by preadsorption of DDAB and SDS. Molybdenum adsorption showed that, over a wide range of concentrations and pH values, the DDAB treated coal adsorbed a higher amount of molybdenum than the samples treated with SDS. The infrared spectroscopy (FTIR) and the atomic force

  20. State coal profiles, January 1994

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-02

    The purpose of State Coal Profiles is to provide basic information about the deposits, production, and use of coal in each of the 27 States with coal production in 1992. Although considerable information on coal has been published on a national level, there is a lack of a uniform overview for the individual States. This report is intended to help fill that gap and also to serve as a framework for more detailed studies. While focusing on coal output, State Coal Profiles shows that the coal-producing States are major users of coal, together accounting for about three-fourths of total US coal consumption in 1992. Each coal-producing State is profiled with a description of its coal deposits and a discussion of the development of its coal industry. Estimates of coal reserves in 1992 are categorized by mining method and sulfur content. Trends, patterns, and other information concerning production, number of mines, miners, productivity, mine price of coal, disposition, and consumption of coal are detailed in statistical tables for selected years from 1980 through 1992. In addition, coal`s contribution to the State`s estimated total energy consumption is given for 1991, the latest year for which data are available. A US summary of all data is provided for comparing individual States with the Nation as a whole. Sources of information are given at the end of the tables.

  1. COAL USE REPORT

    Science.gov (United States)

    The world's coal reserves have been estimated to be about one exagram accessible with current extraction technology. The energy content has been valued at 290 zettajourles. Using a value of 15 terawatt as the current global energy consumption, the coal supply could global needs f...

  2. Coal Industry Burns Hot

    Institute of Scientific and Technical Information of China (English)

    JadaFu

    2003-01-01

    After a rapid boom last year, China's coal industry has continued to grow in 2003. The country has produced 177.27 million tons of coal in the first two months of the year, a year-on-year rise of 17.7 percent.

  3. Improving coal handling effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Walker, S.

    2003-10-01

    Appropriate coal handling systems are essential for successful coal utilisation. The paper looks at some of the options available, including crushers and hammer mills, wear-resistant liners for chutes and wagons, and dewatering systems. These are individual components within larger systems such as stockyard stacking and reclaiming installations. 5 photos.

  4. Development of coal resources

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-01

    It is an important issue to expand stable coal supply areas for Japan, especially to assure stable supply of overseas coals. The investigations on geological structures in foreign countries perform surveys on geological structures in overseas coal producing countries and basic feasibility studies. The investigations select areas with greater business risks in coal producing countries and among private business entities. The geological structure investigations were carried out on China, Indonesia and Malaysia and the basic feasibility studies on Indonesia during fiscal 1994. The basic coal resource development investigations refer to the results of previous physical explorations and drilling tests to develop practical exploration technologies for coal resources in foreign countries. The development feasibility studies on overseas coals conduct technological consultation, surface surveys, physical explorations, and trial drilling operations, and provide fund assistance to activities related thereto. Fiscal 1994 has provided fund assistance to two projects in Indonesia and America. Fund loans are provided on investigations for development and import of overseas coals and other related activities. Liability guarantee for development fund is also described.

  5. FLARE FLAME INSTABILITY AND BURNER COMBUSTION CONTROL

    OpenAIRE

    БОНДАРЕНКО А.В.; В. Э. Волков; Максимов, М. В.

    2014-01-01

    Research of the flare instability development and the laminar-to-turbulent transition for the flares was executed. It was proved that the effects of viscosity and compressibility have the stabilizing influence on the gas flame. The study of the individual flare stability makes the theoretical basis of the fuel burning technology in combustion chambers and for the burner combustion control.

  6. Radical recombinations in acetylene-air flames

    NARCIS (Netherlands)

    Zeegers, P.J.Th.; Alkemade, C.T.J.

    1965-01-01

    In this paper an analysis is given of the behaviour of excess radical concentrations, H, OH and O as a function of height above the reaction zone in premixed acetylene-air flames at 2–200° to 2400°K and 1 atmosphere pressure. The intensity was measured of the Li resonance line which is related to th

  7. Numerical study of one swirling flame

    DEFF Research Database (Denmark)

    Yang, Yang; Kær, Søren Knudsen; Yin, Chungen

    This paper presents numerical study of one of Sydney swirl flames. Good agreements gained between numerical results and the experimental data. Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) methods show different flow patterns in isothermal and reacting case. The influence...

  8. The VLT-FLAMES Tarantula survey

    NARCIS (Netherlands)

    Taylor, W.D.; Evans, C.J.; Henault-Brunet, V.; Bastian, N.; Beletsky, Y.; Bestenlehner, J.; Brott, I.; Cantiello, M.; Carraro, G.; Clark, J.S.; Crowther, P.A.; de Koter, A.; de Mink, S.E.; Doran, E.; Dufton, P.L.; Dunstall, P.; Gieles, M.; Grafener, G.; Herrero, A.; Howarth, I.D.; Langer, N.; Lennon, D.J.; Maiz-Apellaniz, J; Markova, N.; Najarro, P.; Puls, J.; Sana, H.A.A.; Simon-Diaz, S.; Smartt, S.J.; Stroud, V.E.; van Loon, J.T.; Vink, J.S.; Walborn, N.R.

    2011-01-01

    The VLT-FLAMES Tarantula Survey is an ESO Large Programme that has provided multi-epoch spectroscopy of over 1000 stars in the 30 Doradus region in the Large Magellanic Cloud. Armed with this unique dataset the assembled consortium is now addressing a broad range of fundamental questions in both ste

  9. Flame assisted synthesis of catalytic ceramic membranes

    DEFF Research Database (Denmark)

    Johansen, Johnny; Mosleh, Majid; Johannessen, Tue

    2004-01-01

    technology it is possible to make supported catalysts, composite metal oxides, catalytically active surfaces, and porous ceramic membranes. Membrane layers can be formed by using a porous substrate tube (or surface) as a nano-particle filter. The aerosol gas from the flame is led through a porous substrate...

  10. Experiments and modelling on vertical flame spread

    Energy Technology Data Exchange (ETDEWEB)

    Keski-Rahkonen, O.; Mangs, J. [VTT Building and Transport, Espoo (Finland)

    2004-07-01

    he principle and some preliminary results are shown of a new vertical flame spread modelling effort. Quick experimental screenings on relevant phenomena are made, some models are evaluated, and a new set of needed measuring instruments is proposed. Finally a single example of FRNC cable is shown as application of the methods. (orig.)

  11. Brominated flame retardants and endocrine disruption

    NARCIS (Netherlands)

    Vos, J.G.; Becher, G.; Berg, van den M.; Boer, de J.; Leonards, P.E.G.

    2003-01-01

    From an environmental point of view, an increasing important group of organohalogen compounds are the brominated flame retardants (BFRs), which are widely used in polymers and textiles and applied in construction materials, furniture, and electronic equipment. BFRs with the highest production volume

  12. Direct numerical simulations of type Ia supernovae flames II: The Rayleigh-Taylor instability

    Energy Technology Data Exchange (ETDEWEB)

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2004-01-12

    A Type Ia supernova explosion likely begins as a nuclear runaway near the center of a carbon-oxygen white dwarf. The outward propagating flame is unstable to the Landau-Darrieus, Rayleigh-Taylor, and Kelvin-Helmholtz instabilities, which serve to accelerate it to a large fraction of the speed of sound. We investigate the Rayleigh-Taylor unstable flame at the transition from the flamelet regime to the distributed-burning regime, around densities of 10e7 gm/cc, through detailed, fully resolved simulations. A low Mach number, adaptive mesh hydrodynamics code is used to achieve the necessary resolution and long time scales. As the density is varied, we see a fundamental change in the character of the burning--at the low end of the density range the Rayleigh-Taylor instability dominates the burning, whereas at the high end the burning suppresses the instability. In all cases, significant acceleration of the flame is observed, limited only by the size of the domain we are able to study. We discuss the implications of these results on the potential for a deflagration to detonation transition.

  13. Apparatus and method for feeding coal into a coal gasifier

    Science.gov (United States)

    Bissett, Larry A.; Friggens, Gary R.; McGee, James P.

    1979-01-01

    This invention is directed to a system for feeding coal into a gasifier operating at high pressures. A coal-water slurry is pumped to the desired pressure and then the coal is "dried" prior to feeding the coal into the gasifier by contacting the slurry with superheated steam in an entrained bed dryer for vaporizing the water in the slurry.

  14. Laminar Flame Speeds of Gasoline Surrogates Measured with the Flat Flame Method

    KAUST Repository

    Liao, Y.-H.

    2016-01-27

    © 2016 American Chemical Society. The adiabatic, laminar flame speeds of gasoline surrogates at atmospheric pressure over a range of equivalence ratios of = 0.8-1.3 and unburned gas temperatures of 298-400 K are measured with the flat flame method, which produces a one-dimensional flat flame free of stretch. Surrogates used in the current work are the primary reference fuels (PRFs, mixtures of n-heptane and isooctane), the toluene reference fuels (TRFs, mixtures of toluene and PRFs), and the ethanol reference fuels (ERFs, mixtures of ethanol and PRFs). In general, there is good agreement between the present work and the literature data for single-component fuel and PRF mixtures. Surrogates of TRF mixtures are found to exhibit comparable flame speeds to a real gasoline, while there is discrepancy observed between isooctane and gasoline. Moreover, the laminar flame speeds of TRF mixtures with similar fractions of n-heptane are found to be insensitive to the quantity of toluene in the mixture. Mixtures of ERFs exhibit comparable flame speeds to those of TRFs with similar mole fractions of n-heptane and isooctane.

  15. Radiation Heat Transfer in Particle-Laden Gaseous Flame: Flame Acceleration and Triggering Detonation

    CERN Document Server

    Liberman, M A; Kiverin, A D

    2015-01-01

    In this study we examine influence of the radiation heat transfer on the combustion regimes in the mixture, formed by suspension of fine inert particles in hydrogen gas. The gaseous phase is assumed to be transparent for the thermal radiation, while the radiant heat absorbed by the particles is then lost by conduction to the surrounding gas. The particles and gas ahead of the flame is assumed to be heated by radiation from the original flame. It is shown that the maximum temperature increase due to the radiation preheating becomes larger for a flame with lower velocity. For a flame with small enough velocity temperature of the radiation preheating may exceed the crossover temperature, so that the radiation heat transfer may become a dominant mechanism of the flame propagation. In the case of non-uniform distribution of particles, the temperature gradient formed due to the radiation preheating can initiate either deflagration or detonation ahead of the original flame via the Zel'dovich's gradient mechanism. Th...

  16. The flame anchoring mechanism and associated flow structure in bluff-body stabilized lean premixed flames

    Science.gov (United States)

    Michaels, Dan; Shanbhogue, Santosh; Ghoniem, Ahmed

    2015-11-01

    We present numerical analysis of a lean premixed flame anchoring on a heat conducting bluff-body. Different mixtures of CH4/H2/air are analyzed in order to systematically vary the burning velocity, adiabatic flame temperature and extinction strain rate. The study was motivated by our experimental measurements in a step combustor which showed that both the recirculation zone length and stability map under acoustically coupled conditions for different fuels and thermodynamic conditions collapse using the extinction strain rate. The model fully resolves unsteady two-dimensional flow with detailed chemistry and species transport, and without artificial flame anchoring boundary conditions. The model includes a low Mach number operator-split projection algorithm, coupled with a block-structured adaptive mesh refinement and an immersed boundary method for the solid body. Calculations reveal that the recirculation zone length correlates with the flame extinction strain rate, consistent with the experimental evidence. It is found that in the vicinity of the bluff body the flame is highly stretched and its leading edge location is controlled by the reactants combustion characteristics under high strain. Moreover, the flame surface location relative to the shear layer influences the vorticity thus impacting the velocity field and the recirculation zone. The study sheds light on the experimentally observed collapse of the combustor dynamics using the reactants extinction strain rate.

  17. Flame retardancy and its mechanism of polymers flame retarded by DBDPE/Sb2O3

    Institute of Scientific and Technical Information of China (English)

    ZUO Jian-dong; LI Rong-xun; FENG Shao-hua; LIU Guang-ye; ZHAO Jian-qing

    2008-01-01

    The flammability characterization and thermal composition of polymers flame retarded by decabromodiphenylethane(DBDPE) and antimony trioxide (Sb2O3) were studied by cone calorimeter and thermogravimetry (TG). The results show thatABS/DBDPE/Sb2O3 has the similar flammability parameters and thermal composition curves to ABS/DBDPO/Sb3O3. It suggests thatDBDPE/Sb2O3 has the similar flame retardant behavior to DBDPO/Sb2O3. The heat release rate (HRR) and the effect heat combustion (EHC) curves of polymers flame retarded by DBDPE/Sb2O3 all decrease, but the mass loss rate (MLR) curve slightly increase. It shows that the decrease of HRR is not due to the increase of char formation ratio but the generation of incombustible gases. The major flame retardant mechanism of DBDPE/Sb2O3 is gas phase flame retardant mechanism. Increasing content of Sb2O3in DBDPE/Sb2O3 can improve the flame retardant property and thermal stability of aerylonitrile butadiene styrene. Sb203 has a good synergistic effect with DBDPE.

  18. Numerical assessment of accurate measurements of laminar flame speed

    Science.gov (United States)

    Goulier, Joules; Bizon, Katarzyna; Chaumeix, Nabiha; Meynet, Nicolas; Continillo, Gaetano

    2016-12-01

    In combustion, the laminar flame speed constitutes an important parameter that reflects the chemistry of oxidation for a given fuel, along with its transport and thermal properties. Laminar flame speeds are used (i) in turbulent models used in CFD codes, and (ii) to validate detailed or reduced mechanisms, often derived from studies using ideal reactors and in diluted conditions as in jet stirred reactors and in shock tubes. End-users of such mechanisms need to have an assessment of their capability to predict the correct heat released by combustion in realistic conditions. In this view, the laminar flame speed constitutes a very convenient parameter, and it is then very important to have a good knowledge of the experimental errors involved with its determination. Stationary configurations (Bunsen burners, counter-flow flames, heat flux burners) or moving flames (tubes, spherical vessel, soap bubble) can be used. The spherical expanding flame configuration has recently become popular, since it can be used at high pressures and temperatures. With this method, the flame speed is not measured directly, but derived through the recording of the flame radius. The method used to process the radius history will have an impact on the estimated flame speed. Aim of this work is to propose a way to derive the laminar flame speed from experimental recording of expanding flames, and to assess the error magnitude.

  19. Laser-saturated fluorescence measurements in laminar sooting diffusion flames

    Science.gov (United States)

    Wey, Changlie

    1993-01-01

    The hydroxyl radical is known to be one of the most important intermediate species in the combustion processes. The hydroxyl radical has also been considered a dominant oxidizer of soot particles in flames. In this investigation the hydroxyl concentration profiles in sooting diffusion flames were measured by the laser-saturated fluorescence (LSF) method. The temperature distributions in the flames were measured by the two-line LSF technique and by thermocouple. In the sooting region the OH fluorescence was too weak to make accurate temperature measurements. The hydroxyl fluorescence profiles for all four flames presented herein show that the OH fluorescence intensities peaked near the flame front. The OH fluorescence intensity dropped sharply toward the dark region of the flame and continued declining to the sooting region. The OH fluorescence profiles also indicate that the OH fluorescence decreased with increasing height in the flames for all flames investigated. Varying the oxidizer composition resulted in a corresponding variation in the maximum OH concentration and the flame temperature. Furthermore, it appears that the maximum OH concentration for each flame increased with increasing flame temperature.

  20. The behavior of heavy metals in the process of desulfurization of Brazilian coal combustion gases by the addition of limestone

    Directory of Open Access Journals (Sweden)

    Sebag M.G.

    2001-01-01

    Full Text Available The concentrations of heavy metals in two kinds of Brazilian coals at 100° C (acid digestion and at 850° C were studied (ashes the obtained in muffle furnace with and without addition of limestone. Data were analyzed by flame atomic absorption, using the air acetylene flame. For Pb, Zn, Ni, Mn and Cu the metal concentration obtained the acid digestion were higher than metal concentration were obtained in tests in the muffle furnace. This behavior observed in the muffle furnace occurs because these metals are fixed in stable sulfated compounds in the ashes, which are difficult to dissociate at flame temperature, and also due to the volatile character of the metals, mainly Pb and Zn. There was a constant concentration in the ashes in of Cr the acid digestion and muffle furnace tests. Results from tests using an XRD apparatus indicated, he formation of sulfated compounds in the ashes for both. coals. The analysis using microprobe electronic showed retention of metals like Ni, Mn, Cu, Fe, Ti and Ca. For both coals, the low mobility of most of the metals studied occured due to the alkaline pH of sulfated ashes. These metals in the ash from coal combustion in fluidized bed reactor were also studied and showed similar results, enabling a scale-up to pilot scale.

  1. The behavior of heavy metals in the process of desulfurization of Brazilian coal combustion gases by the addition of limestone

    Energy Technology Data Exchange (ETDEWEB)

    Sebag, M.G.; Braganca, S.R.; Normann, M.; Jablonski, A. [Federal University of Rio Grande do Sul, Porto Alegre (Brazil)

    2001-06-01

    The concentrations of heavy metals in two kinds of Brazilian coals at 100deg.C (acid digestion) and at 850deg.C were studied (ashes obtained in the muffle furnace with and without addition of limestone). Data were analyzed by flame atomic absorption, using the air acetylene flame. For Pb, Zn, Ni, Mn and Cu the metal concentration obtained with acid digestion were higher than metal concentration obtained in tests in the muffle furnace. The behavior observed in the muffle furnace occurs because these metals are fixed in stable sulfated compounds in the ashes, which are difficult to dissociate at flame temperature, and also due to the volatile character of the metals, mainly Pb and Zn. There was a constant concentration in the ashes of Cr in the acid digestion and muffle furnace tests. Results from tests using an XRD apparatus indicated the formation of sulfated compounds in the ashes for both. coals. The analysis using microprobe electronic showed retention of metals such as Ni, Mn, Cu, Fe, Ti and Ca. For both coals, the low mobility of most of the metals studied occurred due to the alkaline pH of sulfated ashes. These metals in the ash from coal combustion in fluidized bed reactor were also studied and showed similar results, enabling a scale-up to pilot scale. Short communication.

  2. Leading-Edge Velocities and Lifted Methane Jet Flame Stability

    Directory of Open Access Journals (Sweden)

    W. Wang

    2010-01-01

    Full Text Available Current interest exists in understanding reaction-zone dynamics and mechanisms with respect to how they counterpropagate against incoming reactants. Images of flame position and flow-field morphology are presented from flame chemiluminescence and particle image velocimetry (PIV measurements. In the present study, PIV experiments were carried out to measure the methane jet lifted-flame flow-field velocities in the vicinity of the flame leading edge. Specifically, velocity fields within the high-temperature zone were examined in detail, which complements previous studies, whose prime focus is the flow-field upstream of the high-temperature boundary. PIV data is used not only to determine the velocities, but, along with chemiluminescence images, to also indicate the approximate location of the reaction zone (further supported by/through the leading-edge flame velocity distributions. The velocity results indirectly support the concept that the flame is anchored primarily through the mechanism of partially premixed flame propagation.

  3. Flame quenching process in cavity based on model scramjet combustor

    Institute of Scientific and Technical Information of China (English)

    Yu Pan; Jing Lei; Jian-Han Liang; Wei-Dong Liu; Zhen-Guo Wang

    2012-01-01

    The flame quenching process in combustors was observed by high speed camera and Schlieren system,at the inflow conditions of Ma =2.64,To =1 483 K,P0 =1.65 MPa,T =724 K and P =76.3 kPa.Changing process of the flame and shock structure in the combustor was clearly observed.The results revealed that the precombustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while.The rime of quenching process was extended by the cavity flame holder,and the ability of flame holding was enhanced by arranging more cavities in the downstream as well.The flame was blown from the upstream to the downstream,so the flame in the downstream of the cavity was quenched out later than that in the upstream.

  4. Underground Coal Thermal Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Smith, P. [Univ. of Utah, Salt Lake City, UT (United States); Deo, M. [Univ. of Utah, Salt Lake City, UT (United States); Eddings, E. [Univ. of Utah, Salt Lake City, UT (United States); Sarofim, A. [Univ. of Utah, Salt Lake City, UT (United States); Gueishen, K. [Univ. of Utah, Salt Lake City, UT (United States); Hradisky, M. [Univ. of Utah, Salt Lake City, UT (United States); Kelly, K. [Univ. of Utah, Salt Lake City, UT (United States); Mandalaparty, P. [Univ. of Utah, Salt Lake City, UT (United States); Zhang, H. [Univ. of Utah, Salt Lake City, UT (United States)

    2012-01-11

    The long-term objective of this work is to develop a transformational energy production technology by insitu thermal treatment of a coal seam for the production of substitute natural gas (SNG) while leaving much of the coal's carbon in the ground. This process converts coal to a high-efficiency, low-GHG emitting gas fuel. It holds the potential of providing environmentally acceptable access to previously unusable coal resources. This topical report discusses the development of experimental capabilities, the collection of available data, and the development of simulation tools to obtain process thermo-chemical and geo-thermal parameters in preparation for the eventual demonstration in a coal seam. It also includes experimental and modeling studies of CO2 sequestration.

  5. (Coal utilization in India)

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, R.P.

    1991-01-15

    Under the Phase II, Alternative Energy Resources Development (AERD) project of the United States Agency for International Development (USAID) and the Government of India (GOI), five collaborative coal projects have been initiated in the areas of: (1) NO{sub x}/SO{sub x} control from coal-fired power plants, (2) slagging combustor development for high-ash Indian coals, (3) characterization of Indian coals for combustion and gasification, (4) diagnostic studies for prediction of power plant life expectancy, and (5) environmental and natural resource analysis of coal cycle. The Pittsburgh Energy Technology Center (PETC) has the implementation responsibility for these projects. The Indian collaborative institutions identified for these projects are the Bharat Heavy Electricals Ltd. (BHEL), Trichy, (Projects 1--4), and the Tata Energy Research Institute (TERI) for Project 5. The Oak Ridge National Laboratory (ORNL) is providing cross-cut technical coordination and support for these five projects.

  6. Enzymatic desulfurization of coal

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Y.N.; Crooker, S.C.; Kitchell, J.P.; Nochur, S.V.

    1991-05-16

    The overall objective of this program was to investigate the feasibility of an enzymatic desulfurization process specifically intended for organic sulfur removal from coal. Toward that end, a series of specific objectives were defined: (1) establish the feasibility of (bio)oxidative pretreatment followed by biochemical sulfate cleavage for representative sulfur-containing model compounds and coals using commercially-available enzymes; (2) investigate the potential for the isolation and selective use of enzyme preparations from coal-utilizing microbial systems for desulfurization of sulfur-containing model compounds and coals; and (3) develop a conceptual design and economic analysis of a process for enzymatic removal of organic sulfur from coal. Within the scope of this program, it was proposed to carry out a portion of each of these efforts concurrently. (VC)

  7. Pyrolysis of Indonesian coal

    Energy Technology Data Exchange (ETDEWEB)

    Rachimoellah; Endah [Institut Teknologi Sepuluh Nopemba, Surabaya (Indonesia). Department of Chemical Engineering; Karaman, N.; Kusuma, S.A. [UPN Surabaya, (Indonesia). Department of Chemical Engineering

    1997-04-01

    It has been estimated that there is 36 billion tons of coal resource potential in Indonesia. Over 21.4 billion tons is classified as low rank (lignitic) coal. The coal deposits are located mainly in Sumatra and Kalimantan. As an energy source, low rank coals are not widely used, because of their high moisture content, low calorific value and variable ash content. One of the key questions for utilizing low rank coal is whether lignite can be upgraded into another form which is more economically viable. In this study tests were carried out in a pilot plant fixed bed pyrolysis reactor unit provided with hopper, electric heater, coolers and product receivers. The yield of char, tar and gases was found to depend on temperature which also affected the composition of gas produced. Results also indicated the temperature and particle size giving maximum tar yield, gas concentration, and the atmosphere of inert nitrogen. 1 tab., 2 figs., 10 refs.

  8. Industrial coal utilization

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-01-01

    The effects of the National Energy Act on the use of coal in US industrial and utility power plants are considered. Innovative methods of using coal in an environmentally acceptable way are discussed: furnace types, fluidized-bed combustion, coal-oil-mixtures, coal firing in kilns and combustion of synthetic gas and liquid fuels. Fuel use in various industries is discussed with trends brought about by uncertain availability and price of natural gas and fuel oils: steel, chemical, cement, pulp and paper, glass and bricks. The symposium on Industrial Coal Utilization was sponsored by the US DOE, Pittsburgh Energy Technology Center, April 3 to 4, 1979. Twenty-one papers have been entered individually into the EDB. (LTN)

  9. Industrial coal utilization

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-01-01

    The effects of the National Energy Act on the use of coal in US industrial and utility power plants are considered. Innovative methods of using coal in an environmentally acceptable way are discussed: furnace types, fluidized-bed combustion, coal-oil-mixtures, coal firing in kilns and combustion of synthetic gas and liquid fuels. Fuel use in various industries is discussed with trends brought about by uncertain availability and price of natural gas and fuel oils: steel, chemical, cement, pulp and paper, glass and bricks. The symposium on Industrial Coal Utilization was sponsored by the US DOE, Pittsburgh Energy Technology Center, April 3 to 4, 1979. Twenty-one papers have been entered individually into the EDB. (LTN)

  10. The development of low NOx burners under the IEA Coal Combustion Sciences agreement

    Energy Technology Data Exchange (ETDEWEB)

    Whaley, H. [CANMET Energy Technology Centre, Ottawa, Ontario (Canada)

    1997-09-01

    Canada has been involved in the International Energy Agency (IEA) implementing agreement on coal combustion sciences since 1985. The other countries belonging to this agreement are Australia, Germany, Denmark, Finland, Italy, the Netherlands, Sweden, the United Kingdom and the US. There are two operating annexes, the first, Annex 1 being task-shared, in which designated research projects within the participating countries are reported on an annual basis. Annex 2 is cost-shared and the research is conducted at the International Flame Research Foundation (IFRF) in the Netherlands and paid for by the participants, Canada, Germany, the Netherlands and the UK. The objectives of Annex 2 are to develop advanced low NOx coal burners for power boilers and to characterize their performance with a wide range of coals and coal blends. Two burners have been selected as showing great promise in suppressing NOx formation, thereby reducing emissions to below regulatory levels. One is an aerodynamically air-staged burner (AASB) and the other an internally fuel-staged burner (IFSB). Both can utilize a single boiler entry port, which makes them ideal for retrofitting, the former relies on combustion air staging, the latter on fuel staging or reburning. The IFSB, when developed to a commercial stage, is anticipated to meet projected Canadian NOx regulations for the foreseeable future. Supplementary aspects of the program have been coal characterization, ash behavior and deposition, advanced in-flame measurement technique development and validation data bases for flame, combustion and NOx modeling. This presentation will focus on the two low NOx burners developed under the Annex 2 program.

  11. Flame Propagation of Butanol Isomers/Air Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Veloo, Peter S.; Egolfopoulos, Fokion N.

    2011-01-01

    An experimental and computational study was conducted on the propagation of flames of saturated butanol isomers. The experiments were performed in the counterflow configuration under atmospheric pressure, unburned mixture temperature of 343 K, and for a wide range of equivalence ratios. The experiments were simulated using a recent kinetic model for the four isomers of butanol. Results indicate that n-butanol/air flames propagate somewhat faster than both sec-butanol/air and iso-butanol/air flames, and that tert-butanol/air flames propagate notably slower compared to the other three isomers. Reaction path analysis of tert-butanol/air flames revealed that iso-butene is a major intermediate, which subsequently reacts to form the resonantly stable iso-butenyl radical retarding thus the overall reactivity of tert-butanol/air flames relatively to the other three isomers. Through sensitivity analysis, it was determined that the mass burning rates of sec-butanol/air and iso-butanol/air flames are sensitive largely to hydrogen, carbon monoxide, and C{sub 1}–C{sub 2} hydrocarbon kinetics and not to fuel-specific reactions similarly to n-butanol/air flames. However, for tert-butanol/air flames notable sensitivity to fuel-specific reactions exists. While the numerical results predicted closely the experimental data for n-butanol/air and sec-butanol/air flames, they overpredicted and underpredicted the laminar flame speeds for iso-butanol/air and tert-butanol/air flames respectively. It was demonstrated further that the underprediction of the laminar flame speeds of tert-butanol/air flames by the model was most likely due to deficiencies of the C{sub 4}-alkene kinetics.

  12. Shapes of Buoyant and Nonbuoyant Methane Laminar Jet Diffusion Flames

    Science.gov (United States)

    Sunderland, Peter B.; Yuan, Zeng-Guang; Urban, David L.

    1997-01-01

    Laminar gas jet diffusion flames represent a fundamental combustion configuration. Their study has contributed to numerous advances in combustion, including the development of analytical and computational combustion tools. Laminar jet flames are pertinent also to turbulent flames by use of the laminar flamelet concept. Investigations into the shapes of noncoflowing microgravity laminar jet diffusion flames have primarily been pursued in the NASA Lewis 2.2-second drop tower, by Cochran and coworkers and by Bahadori and coworkers. These studies were generally conducted at atmospheric pressure; they involved soot-containing flames and reported luminosity lengths and widths instead of the flame-sheet dimensions which are of Greater value to theory evaluation and development. The seminal model of laminar diffusion flames is that of Burke and Schumann, who solved the conservation of momentum equation for a jet flame in a coflowing ambient by assuming the velocity of fuel, oxidizer and products to be constant throughout. Roper and coworkers improved upon this model by allowing for axial variations of velocity and found flame shape to be independent of coflow velocity. Roper's suggestion that flame height should be independent of gravity level is not supported by past or present observations. Other models have been presented by Klajn and Oppenheim, Markstein and De Ris, Villermaux and Durox, and Li et al. The common result of all these models (except in the buoyant regime) is that flame height is proportional to fuel mass flowrate, with flame width proving much more difficult to predict. Most existing flame models have been compared with shapes of flames containing soot, which is known to obscure the weak blue emission of flame sheets. The present work involves measurements of laminar gas jet diffusion flame shapes. Flame images have been obtained for buoyant and nonbuoyant methane flames burning in quiescent air at various fuel flow-rates, burner diameters and ambient

  13. Combustion development of an industrial scale burner, with particular reference to coal blends and co-firing coal with natural gas and sawdust

    Energy Technology Data Exchange (ETDEWEB)

    Allen, G. [International Combustion Limited, Derby (United Kingdom). Rolls Royce Industrial Power Group

    1998-12-31

    Described herein are the results of pulverised coal combustion experiments performed on a 35 MWth low NO{sub x} burner installed in International Combustion`s large scale combustion test facility. In-flame and furnace exit combustion/emissions species and temperature measurements were taken during firing trials with: different coal blends; a coal-wood dust fuel blend; coal and natural gas `In-Burner` co-firing. The NO{sub x} and unburned carbon in ash results generated from the coal blend tests were shown to correlate well against fuel ratio. The gas co-firing results confirmed low momentum gas injection along the burner axis as optimum. This reduced NO{sub x} by 16% whilst unburned carbon in ash fell from 3 to 1.5%. Larger NO{sub x} reductions were anticipated by virtue of activating an `In-Burner` gas reburn de-NO{sub x} process. A 1/2th scale isothermal low NO{sub x} burner model was used to characterise pulverized coal particle (PF) dynamics in the near burner region. Laser sheet velocimetry and laser doppler anemometry measurements indicated that the larger PF particles follow a straight trajectory and penetrate the burner internal recirculation zone. Conversely, the smaller PF particles are drawn radially outwards into the shear layer between the burner PA and SA flow streams to initiate combustion. A CFD model of this burner was validated against the experimental data. This exercise highlighted the importance of specifying accurate CFD model inlet boundary conditions, adopting fine grids, and selecting appropriate turbulence models. This mathematical model was subsequently used to derive new flame stabiliser concepts, which were tested on a full size burner. 9 refs., 27 figs., 8 tabs.

  14. Behaviors of tribrachial edge flames and their interactions in a triple-port burner

    KAUST Repository

    Yamamoto, Kazuhiro

    2015-05-01

    In a triple-port burner, various non-premixed flames have been observed previously. Especially for the case with two lifted flames, such configuration could be suitable in studying interaction between two tribrachial flames. In the present study, the flame characteristics have been investigated numerically by adopting a reduced kinetic mechanism in the triple-port burner. Four different types of flame configurations, including two attached flames, inner lifted/outer attached flames, inner attached/outer lifted flames, and twin lifted flames, were successfully simulated depending on the flow conditions. The representative edge propagation speed of a single lifted flame or an upstream lifted flame in the case of twin lifted flames increased as the liftoff height became higher. In the twin lifted flames, the inner lifted flame was affected appreciably when the other flame was located further upstream such that the lifted flame located further downstream encountered the axial velocity acceleration induced by the gas expansion from the lifted flame located upstream, while thermal effects were not observed since the temperature of the incoming flow toward the lifted flame was not affected. A unique flip-flop behavior between the inner and outer flames, observed experimentally previously, was successfully captured in the simulation such that the inner lifted flame became attached to the nozzle as the liftoff height of the outer lifted flame grew higher with an increase in the outer air velocity.

  15. Imaging the Underground Coal Gasification Zone with Microgravity Surveys

    Directory of Open Access Journals (Sweden)

    Kotyrba Andrzej

    2015-06-01

    Full Text Available The paper describes results of microgravity measurements made on the surface over an underground geo reactor where experimental coal gasification was performed in a shallow seam of coal. The aim of the research was to determine whether, and to what extent, the microgravity method can be used to detect and image a coal gasification zone, especially caverns where the coal was burnt out. In theory, the effects of coal gasification process create caverns and cracks, e.g., zones of altered bulk density. Before the measurements, theoretical density models of completely and partially gasified coal were analysed. Results of the calculations of gravity field response showed that in both cases on the surface over the gasification zone there should be local gravimetric anomalies. Over the geo reactor, two series of gravimetric measurements prior to and after gasification were conducted. Comparison of the results of two measurement series revealed the presence of gravimetric anomalies that could be related to the cavern formation process. Data from these measurements were used to verify theoretical models. After the experiment, a small cavern was detected at the depth of the coal seam by the test borehole drilled in one of the anomalous areas.

  16. Imaging the Underground Coal Gasification Zone with Microgravity Surveys

    Science.gov (United States)

    Kotyrba, Andrzej; Kortas, Łukasz; Stańczyk, Krzysztof

    2015-06-01

    The paper describes results of microgravity measurements made on the surface over an underground geo reactor where experimental coal gasification was performed in a shallow seam of coal. The aim of the research was to determine whether, and to what extent, the microgravity method can be used to detect and image a coal gasification zone, especially caverns where the coal was burnt out. In theory, the effects of coal gasification process create caverns and cracks, e.g., zones of altered bulk density. Before the measurements, theoretical density models of completely and partially gasified coal were analysed. Results of the calculations of gravity field response showed that in both cases on the surface over the gasification zone there should be local gravimetric anomalies. Over the geo reactor, two series of gravimetric measurements prior to and after gasification were conducted. Comparison of the results of two measurement series revealed the presence of gravimetric anomalies that could be related to the cavern formation process. Data from these measurements were used to verify theoretical models. After the experiment, a small cavern was detected at the depth of the coal seam by the test borehole drilled in one of the anomalous areas.

  17. Attachment of Sulfolobus acidocaldarius cells on coal particles

    Energy Technology Data Exchange (ETDEWEB)

    Chiu-Yu Chen; Skidmore, D.R.

    1988-03-01

    Attachment of the thermophilic microorganism Sulfolobus acidocaldarius was studied on Kentucky No. 9 coal, an Ohio coal mixtures, Ohio No. 6, a European coal designated as Sulzer coal, activated carbon and iron pyrite to define the effects of initial cell density, prior acid leaching, pyrite content, and surface area on rate and extent of preleaching attachment. The results showed that the rate of preleaching attachment was so high that equilibrium was reached in less than 5 min in most cases. Attached cells increased in number with increasing initial cell density. Prior nitric acid leaching of coal reduced the extent of cell adsorption while hydrochloric acid leaching did not affect cell attachment. Some adsorption isotherms fit the Langmuir model. The specific adsorption (cells/cm/sup 3/ coal) increased with increasing surface areas measured by nitrogen adsorption. Pyrite gave the highest extent of cell attachment based on per unit surface area comparison. Adsorption isotherms of a pyrite-selective chemical adsorbate revealed that preleaching attachment of cells was affected further by altered surface properties of the coals and that the concept of selective attachment of cells on pyrite surfaces was also supported. 22 refs., 6 figs., 1 tab.

  18. Vibrated fluidized bed air classification of moist raw coal

    Institute of Scientific and Technical Information of China (English)

    杨国华; 赵跃民; 陈清如

    2002-01-01

    Vibrated fluidized bed air classification is completely different from traditional screening in principle. It extracts fine coal from moist raw coal by entrainment of an ascending airflow in a vibrated fluidized bed. Pilot tests showed that air classification efficiencies varied from 74.85% to 93.84% at cut-size 6, 4, 3, 2, 1, and 0.5 mm when free moisture of coal is in the range of 1.7% to 9.5%, and ash contents of fine coal products were 2%~3% lower than those of the same size fractions in feed, and 4%~10% lower than those of feeds for most cases because of the density differences between coal and waste, which is beneficial to producing lower ash fine coal from raw coal as fuel of blast furnaces or pulverized coal firing boilers. A commercial unit of 100 t/h has been in smooth operation, and several 300~400 t/h units are in plan or construction.

  19. Economic Limit of Coal Mining Closedown in Restructuring Coal Industry

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    One of the key points in restructuring the coal industry is to close some deficient coal mines which haveneither economic result nor social benefit. Based on the relationship among production, cost, and profit, differenteconomic limits for closing coal mines in different cases were put forward. The relationship between the profit andclosedown cost of deficient coal mines was analyzed and an overall economic limit for closing a deficient coal minewas also proposed.

  20. Coal Activities for Secondary Students.

    Science.gov (United States)

    American Coal Foundation, Washington, DC.

    This collection of lesson plans designed for teachers of 4th- through 12th-grade students utilizes an assortment of teaching strategies for topics related to coal and the coal industry. Activities cover the following topics: coal formation; coal identification; "the geologist's dilemma" (a supply and demand activity); geologic time and the…

  1. Transportation of coal by pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Round, G.F.

    1982-01-01

    Discusses Canada's coal resources, technology of long distance coal slurry pipelines, existing and planned coal slurry pipelines, their economics, liquid carbon dioxide, methanol and crude oil instead of water as carrier fluid, and coal slurry research in Canada.

  2. Permeability changes in coal resulting from gas desorption

    Energy Technology Data Exchange (ETDEWEB)

    Levine, J.R.; Tsay, F.

    1990-01-01

    Measurement of sorption capacity of coals by microbalance in a high pressure environment requires that corrections be made for the buoyancy of the gas that is displaced by the solid coal. As the pressure increases, the gas density increases, requiring that a correction factor be applied to the weight of the sample as measured by microbalance. A brief report summarizing this correction is attached as Appendix A.

  3. Validation of a Monte Carlo method using a joint PDF of the composition and an ILDM kinetic model for the prediction of turbulent flames

    Energy Technology Data Exchange (ETDEWEB)

    Zurbach, S.; Garreton, D.; Kanniche, M.

    1997-09-01

    The resolution of the joint probability density function (PDF) of the composition and its application to the calculation of turbulent diffusion flames is presented. The numerical method is based on an Eulerian Monte-Carlo solver coupled with the CFD code Hades; an ILDM kinetic model allows the calculation of the chemical source terms. Two configurations are studied: the Masri-Bilger-Dibble flame and the Delft flame. The first turbulent diffusion flame is close to extinction and is a good test for the prediction of the interactions between the turbulence and the chemicals scales. The second one enables the validation of the prediction of an intermediate species taking a super-equilibrium concentration, the OH radical. (author) 9 refs.

  4. Electrospun core-shell microfiber separator with thermal-triggered flame-retardant properties for lithium-ion batteries

    Science.gov (United States)

    Liu, Kai; Liu, Wei; Qiu, Yongcai; Kong, Biao; Sun, Yongming; Chen, Zheng; Zhuo, Denys; Lin, Dingchang; Cui, Yi

    2017-01-01

    Although the energy densities of batteries continue to increase, safety problems (for example, fires and explosions) associated with the use of highly flammable liquid organic electrolytes remain a big issue, significantly hindering further practical applications of the next generation of high-energy batteries. We have fabricated a novel “smart” nonwoven electrospun separator with thermal-triggered flame-retardant properties for lithium-ion batteries. The encapsulation of a flame retardant inside a protective polymer shell has prevented direct dissolution of the retardant agent into the electrolyte, which would otherwise have negative effects on battery performance. During thermal runaway of the lithium-ion battery, the protective polymer shell would melt, triggered by the increased temperature, and the flame retardant would be released, thus effectively suppressing the combustion of the highly flammable electrolytes. PMID:28097221

  5. Electrospun core-shell microfiber separator with thermal-triggered flame-retardant properties for lithium-ion batteries.

    Science.gov (United States)

    Liu, Kai; Liu, Wei; Qiu, Yongcai; Kong, Biao; Sun, Yongming; Chen, Zheng; Zhuo, Denys; Lin, Dingchang; Cui, Yi

    2017-01-01

    Although the energy densities of batteries continue to increase, safety problems (for example, fires and explosions) associated with the use of highly flammable liquid organic electrolytes remain a big issue, significantly hindering further practical applications of the next generation of high-energy batteries. We have fabricated a novel "smart" nonwoven electrospun separator with thermal-triggered flame-retardant properties for lithium-ion batteries. The encapsulation of a flame retardant inside a protective polymer shell has prevented direct dissolution of the retardant agent into the electrolyte, which would otherwise have negative effects on battery performance. During thermal runaway of the lithium-ion battery, the protective polymer shell would melt, triggered by the increased temperature, and the flame retardant would be released, thus effectively suppressing the combustion of the highly flammable electrolytes.

  6. Cooperative research in coal liquefaction. Technical progress report, May 1, 1993--April 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, G.P. [ed.

    1994-10-01

    Accomplishments for the past year are presented for the following tasks: coliquefaction of coal with waste materials; catalysts for coal liquefaction to clean transportation fuels; fundamental research in coal liquefaction; and in situ analytical techniques for coal liquefaction and coal liquefaction catalysts some of the highlights are: very promising results have been obtained from the liquefaction of plastics, rubber tires, paper and other wastes, and the coliquefaction of wastes with coal; a number of water soluble coal liquefaction catalysts, iron, cobalt, nickel and molybdenum, have been comparatively tested; mossbauer spectroscopy, XAFS spectroscopy, TEM and XPS have been used to characterize a variety of catalysts and other samples from numerous consortium and DOE liquefaction projects and in situ ESR measurements of the free radical density have been conducted at temperatures from 100 to 600{degrees}C and H{sub 2} pressures up to 600 psi.

  7. Study and modeling of finite rate chemistry effects in turbulent non-premixed flames

    Science.gov (United States)

    Vervisch, Luc

    1993-01-01

    The development of numerical models that reflect some of the most important features of turbulent reacting flows requires information about the behavior of key quantities in well defined combustion regimes. In turbulent flames, the coupling between turbulent and chemical processes is so strong that it is extremely difficult to isolate the role played by one individual physical phenomenon. Direct numerical simulation (hereafter DNS) allows us to study in detail the turbulence-chemistry interaction in some restricted but completely defined situations. Globally, non-premixed flames are controlled by two limiting regimes: the fast chemistry case, where the turbulent flame can be pictured as a random distribution of local chemical equilibrium problems; and the slow chemistry case, where the chemistry integrates in time the turbulent fluctuations. The Damkoehler number, ratio of a mechanical time scale to chemical time scale, is used to distinguish between these regimes. Today most of the industrial computer codes are able to perform predictions in the hypothesis of local equilibrium chemistry using a presumed shape for the probability density function (pdt) of the conserved scalar. However, the finite rate chemistry situation is of great interest because industrial burners usually generate regimes in which, at some points, the flame is undergoing local extinction or at least non-equilibrium situations. Moreover, this variety of situations strongly influences the production of pollutants. To quantify finite rate chemistry effect, the interaction between a non-premixed flame and a free decaying turbulence is studied using DNS. The attention is focused on the dynamic of extinction, and an attempt is made to quantify the effect of the reaction on the small scale mixing process. The unequal diffusivity effect is also addressed. Finally, a simple turbulent combustion model based on the DNS observations and tractable in real flow configurations is proposed.

  8. Coal Mines Security System

    Directory of Open Access Journals (Sweden)

    Ankita Guhe

    2012-05-01

    Full Text Available Geological circumstances of mine seem to be extremely complicated and there are many hidden troubles. Coal is wrongly lifted by the musclemen from coal stocks, coal washeries, coal transfer and loading points and also in the transport routes by malfunctioning the weighing of trucks. CIL —Coal India Ltd is under the control of mafia and a large number of irregularities can be contributed to coal mafia. An Intelligent Coal Mine Security System using data acquisition method utilizes sensor, automatic detection, communication and microcontroller technologies, to realize the operational parameters of the mining area. The data acquisition terminal take the PIC 16F877A chip integrated circuit as a core for sensing the data, which carries on the communication through the RS232 interface with the main control machine, which has realized the intelligent monitoring. Data management system uses EEPROM chip as a Black box to store data permanently and also use CCTV camera for recording internal situation. The system implements the real-time monitoring and displaying for data undermine, query, deletion and maintenance of history data, graphic statistic, report printing, expert diagnosis and decision-making support. The Research, development and Promote Application will provide the safeguard regarding the mine pit control in accuracy, real-time capacity and has high reliability.

  9. Effects of side walls on facade flame entrainment and flame height from opening in compartment fires

    Directory of Open Access Journals (Sweden)

    Hu L.H.

    2013-11-01

    Full Text Available This paper presents an investigation of the side wall effects on facade flames ejected from the opening (such as a window of an under-ventilated room fire. Experiments are carried out in a reduced-scale experimental setup, consisting of a cubic fire compartment having an opening with a vertical facade wall and two side walls normal to the façade wall. By changing the distance of the two side walls, the facade flame heights for different opening conditions (width, height are recorded by a CCD camera. It is found that as the distance of the two side walls decreases the behavior the flame height can be distinguished into two regimes characterized by the dimensionless excess heat release rate, $skew5dot{Q}_{ex}^{ast}$ See Formula in PDF , outside the opening: (a for the “wall fire” (skew5dot{Q}_{ex}^{ast }$See Formula in PDF ≤ 1.3 , the flame height is shown to change little with decrease of side wall distance as the dominant entrainment is from the front direction (normal to the facade wall independent of the side wall distances; (b for the “axis-symmetrical fire” (\\skew5dot{Q}_{ex}^{ast}$ > 1.3, the flame height increases significantly with a decrease in side wall distance as both the entrainment from the two side directions (parallel to the facade wall and that from the front direction (normal to the facade wall together apply. A global physically based non-dimensional factor K is then brought forward based on the side wall constraint effect on the facade flame entrainment to characterize the side wall effect on the flame height, by accounting for the dimensionless excess heat release rate, the characteristic length scales of the opening as well as the side wall separation distance. The experimental data for different opening dimensions and side wall distances collapse by using this global non-dimensional factor.

  10. Industrial role of coal chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Dierk, E.A.; Stadelhofer, J.W.

    1983-02-07

    The paper is concerned with the production of coal-based chemicals either from the by-products of coal carbonization, or from synthesis gas manufactured from coal. The potential of coal tar as a raw material for chemicals synthesis forms the basis of the paper. Koppers-Totzek and Lurgi gasification processes and Fischer-Tropsch synthesis are considered, and, finally, coal liquefaction processes are briefly mentioned.

  11. Clean coal technology: The new coal era

    Energy Technology Data Exchange (ETDEWEB)

    1994-01-01

    The Clean Coal Technology Program is a government and industry cofunded effort to demonstrate a new generation of innovative coal processes in a series of full-scale showcase`` facilities built across the country. Begun in 1986 and expanded in 1987, the program is expected to finance more than $6.8 billion of projects. Nearly two-thirds of the funding will come from the private sector, well above the 50 percent industry co-funding expected when the program began. The original recommendation for a multi-billion dollar clean coal demonstration program came from the US and Canadian Special Envoys on Acid Rain. In January 1986, Special Envoys Lewis and Davis presented their recommendations. Included was the call for a 5-year, $5-billion program in the US to demonstrate, at commercial scale, innovative clean coal technologies that were beginning to emerge from research programs both in the US and elsewhere in the world. As the Envoys said: if the menu of control options was expanded, and if the new options were significantly cheaper, yet highly efficient, it would be easier to formulate an acid rain control plan that would have broader public appeal.

  12. Assessing Pediatric Nurses' Knowledge About Chemical Flame Retardants.

    Science.gov (United States)

    Distelhorst, Laura; Bieda, Amy; DiMarco, Marguerite; Tullai-McGuinness, Susan

    Chemical flame retardants are routinely applied to children's products and are harmful to their health. Pediatric nurses are in a key position to provide education to caregivers on methods to decrease their children's exposure to these harmful chemicals. However, a critical barrier is the absence of any program to educate nurses about chemical flame retardants. In order to overcome this barrier, we must first assess their knowledge. This article provides key highlights every pediatric nurse should know about chemical flame retardants and reports the results of a knowledge assessment study. The purpose of this study was to (1) assess pediatric nurses' knowledge of chemical flame retardants, (2) determine what topic areas of chemical flame retardants pediatric nurses lack knowledge in, and (3) determine the best method to educate nurses about chemical flame retardants. A single sample cross-sectional questionnaire design was used. A total sample of 417 advanced practice registered nurses and registered nurses completed an online survey about chemical flame retardants. Pediatric nurses' knowledge of chemical flame retardants was low (M=13.4 out of 51). Articles, webinars, and e-mails were the primary preferred methods for education on the subject identified as a result of the survey. Pediatric nurses have a large knowledge deficit related to chemical flame retardants. The data collected from this study will help structure future educational formats for pediatric nurses on chemical flame retardants to increase their knowledge. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. A Systematic Analysis of Coal Accumulation Process

    Institute of Scientific and Technical Information of China (English)

    CHENG Aiguo

    2008-01-01

    Formation of coal seam and coal-rich zone is an integrated result of a series of factors in coal accumulation process. The coal accumulation system is an architectural aggregation of coal accumulation factors. It can be classified into 4 levels: the global coal accumulation super-system, the coal accumulation domain mega.system, the coal accumulation basin system, and the coal seam or coal seam set sub-system. The coal accumulation process is an open, dynamic, and grey system, and is meanwhile a system with such natures as aggregation, relevance, entirety, purpose-orientated, hierarchy, and environment adaptability. In this paper, we take coal accumulation process as a system to study origin of coal seam and coal-rich zone; and we will discuss a methodology of the systematic analysis of coal accumulation process. As an example, the Ordos coal basin was investigated to elucidate the application of the method of the coal accumulation system analysis.

  14. On the formation and early evolution of soot in turbulent nonpremixed flames

    KAUST Repository

    Bisetti, Fabrizio

    2012-01-01

    A Direct Numerical Simulation (DNS) of soot formation in an n-heptane/air turbulent nonpremixed flame has been performed to investigate unsteady strain effects on soot growth and transport. For the first time in a DNS of turbulent combustion, Polycyclic Aromatic Hydrocarbons (PAH) are included via a validated, reduced chemical mechanism. A novel statistical representation of soot aggregates based on the Hybrid Method of Moments is used [M.E. Mueller, G. Blanquart, H. Pitsch, Combust. Flame 156 (2009) 1143-1155], which allows for an accurate state-of-the-art description of soot number density, volume fraction, and morphology of the aggregates. In agreement with previous experimental studies in laminar flames, Damköhler number effects are found to be significant for PAH. Soot nucleation and growth from PAH are locally inhibited by high scalar dissipation rate, thus providing a possible explanation for the experimentally observed reduction of soot yields at increasing levels of mixing in turbulent sooting flames. Furthermore, our data indicate that soot growth models that rely on smaller hydrocarbon species such as acetylene as a proxy for large PAH molecules ignore or misrepresent the effects of turbulent mixing and hydrodynamic strain on soot formation due to differences in the species Damköhler number. Upon formation on the rich side of the flame, soot is displaced relative to curved mixture fraction iso-surfaces due to differential diffusion effects between soot and the gas-phase. Soot traveling towards the flame is oxidized, and aggregates displaced away from the flame grow primarily by condensation of PAH on the particle surface. In contrast to previous DNS studies based on simplified soot and chemistry models, surface reactions are found to contribute barely to the growth of soot, for nucleation and condensation processes occurring in the fuel stream are responsible for the most of soot mass generation. Furthermore, the morphology of the soot aggregates is

  15. Early structure of LPG partially premixed conically stabilized flames

    KAUST Repository

    Elbaz, Ayman M.

    2013-01-01

    This paper presents experimental investigation of LPG partially premixed turbulent flames stabilized within a conical nozzle burner under constant degree of partial premixing. The stability limits and mean flame structure are presented based on the mean gas temperature and the concentration of CO, O 2, NO, and HC at the flame early region of reaction. The investigation covered the influence of the nozzle cone angle, the jet exit velocity and the jet equivalence ratio. The stability results show that the flames with cone are more stable than those without cone. For conical stabilized flames, the stability results exhibit three different sensitivity regions between the jet velocity and equivalence ratio. The inflame measurements prove that the flame stability could be attributed to the triple flame structure at the flame leading edge. The data show that the triple flame structure is influenced by cone angle, the jet velocity and the equivalence ratio. The flame is believed to be controlled by the recirculation flow inside the cone. Increasing the cone angle induced higher air entrainment to the reaction zone as depicted by a higher O 2 concentration within the flame leading edge. Increasing the jet velocity to a certain limit enhances the intensity of combustion at the flame leading edge, while excessive increase in jet velocity reduces this intensity. At a fixed jet velocity the higher the equivalence ratio, the higher the amount of fuel diffused and engulfed to the reaction zone, the more delay of the combustion completion and the higher the emission concentrations of the flame. © 2012 Elsevier Inc.

  16. Flame spread over inclined electrical wires with AC electric fields

    KAUST Repository

    Lim, Seung J.

    2017-07-21

    Flame spread over polyethylene-insulated electrical wires was studied experimentally with applied alternating current (AC) by varying the inclination angle (θ), applied voltage (VAC), and frequency (fAC). For the baseline case with no electric field applied, the flame spread rate and the flame width of downwardly spreading flames (DSFs) decreased from the horizontal case for −20° ≤ θ < 0° and maintained near constant values for −90° ≤ θ < −20°, while the flame spread rate increased appreciably as the inclination angle of upwardly spreading flames (USFs) increased. When an AC electric field was applied, the behavior of flame spread rate in DSFs (USFs) could be classified into two (three) sub-regimes characterized by various functional dependences on VAC, fAC, and θ. In nearly all cases of DSFs, a globular molten polyethylene formed ahead of the spreading flame edge, occasionally dripping onto the ground. In these cases, an effective flame spread rate was defined to represent the burning rate by measuring the mass loss due to dripping. This effective spread rate was independent of AC frequency, while it decreased linearly with voltage and was independent of the inclination angle. In DSFs, when excessively high voltage and frequency were applied, the dripping led to flame extinction during propagation and the extinction frequency correlated well with applied voltage. In USFs, when high voltage and frequency were applied, multiple globular molten PEs formed at several locations, leading to ejections of multiple small flame segments from the main flame, thereby reducing the flame spread rate, which could be attributed to the electrospray phenomenon.

  17. Clean coal initiatives in Indiana

    Science.gov (United States)

    Bowen, B.H.; Irwin, M.W.; Sparrow, F.T.; Mastalerz, Maria; Yu, Z.; Kramer, R.A.

    2007-01-01

    Purpose - Indiana is listed among the top ten coal states in the USA and annually mines about 35 million short tons (million tons) of coal from the vast reserves of the US Midwest Illinois Coal Basin. The implementation and commercialization of clean coal technologies is important to the economy of the state and has a significant role in the state's energy plan for increasing the use of the state's natural resources. Coal is a substantial Indiana energy resource and also has stable and relatively low costs, compared with the increasing costs of other major fuels. This indigenous energy source enables the promotion of energy independence. The purpose of this paper is to outline the significance of clean coal projects for achieving this objective. Design/methodology/approach - The paper outlines the clean coal initiatives being taken in Indiana and the research carried out at the Indiana Center for Coal Technology Research. Findings - Clean coal power generation and coal for transportation fuels (coal-to-liquids - CTL) are two major topics being investigated in Indiana. Coking coal, data compilation of the bituminous coal qualities within the Indiana coal beds, reducing dependence on coal imports, and provision of an emissions free environment are important topics to state legislators. Originality/value - Lessons learnt from these projects will be of value to other states and countries.

  18. Coal potential of Antartica

    Energy Technology Data Exchange (ETDEWEB)

    Rose, G.; McElroy, C.T.

    1987-01-01

    This report attempts to bring together available information on the coal deposits of Antarctica and discuss factors that would be involved if these deposits were to be explored and mined. Most of the reported principal coal deposits in Antarctica lie generally within the Transantarctic Mountains: the majority are of Permian age and are present in the Victoria Group of the Beacon Supergroup. Several other deposits have been recorded in East Antarctica and in the Antarctic Peninsula, including minor occurrences of Mesozoic and Tertiary coal and carbonaceous shale.

  19. Coal-fired generation

    CERN Document Server

    Breeze, Paul

    2015-01-01

    Coal-Fired Generation is a concise, up-to-date and readable guide providing an introduction to this traditional power generation technology. It includes detailed descriptions of coal fired generation systems, demystifies the coal fired technology functions in practice as well as exploring the economic and environmental risk factors. Engineers, managers, policymakers and those involved in planning and delivering energy resources will find this reference a valuable guide, to help establish a reliable power supply address social and economic objectives. Focuses on the evolution of the traditio

  20. Coal slurry - a problem of the brown coal industry

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, H.; Hielscher, R.; Mohry, J.

    1983-01-01

    Technological and economic aspects are examined for processing coal-containing waste water from brown coal preparation plants in the German Democratic Republic. In 1979, 106.8 Mm/sup 3/ of coal slurry were produced by the GDR brown coal industry, with a coal fine content ranging between 7.8 g/l and 20.4 g/l. This amounts to 2.6 Mt/y of coal which is 1% of the annual brown coal production. Technological variants of processing and utilizing coal slurry are discussed. At a number of major coal preparation plants, coal slurry is flushed into sedimentation lakes. After a 2 to 3 year drying period, a 6 to 10 m thick layer of coal is recovered. Technologies of coal slurry processing with the aim of recovering coal fines are enumerated. Equipment for these processes include, filters, centrifuges, dryers, etc. Recovered coal can be used as fuel or processed into fertilizer in combination with fly ash and other waste products. 12 references.