05261 An improved model for fixed-bed coal combustion and gasification: sensitivity analysis and applications

05261 An improved model for fixed-bed coal combustion and gasification: sensitivity analysis and applications

09 Combustion (burners, combustion systems) 96105245 An experimental study on the organic pollutants discharged from coal combustion Yan, R. and Ka...

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09

Combustion (burners, combustion systems)

96105245

An experimental study on the organic pollutants discharged from coal combustion Yan, R. and Kang, Z. Huazhong Ligong Darue Xuebao, 1996, 24, (l), 4-7. (In Chinese) The paper discusses organic pollutants contained in ash and fly gas released from combustion of different types of coal under varying conditions and those in CH,CI, coal extracts were determined by gas chromatography/mass SpectrometryiIR to study the distribution of pollutants in combustion wastes.

96105254 Fragmentation burning In reglme I

of hlghly

porous

char particles

Zhang, X. ef al., Combustion & Flame, Jul. 1996, 106, (l), 203-206. The purpose of this note is to present the recent observation of the details of the process of breakage and fragmentation of highly porous char particles burning in regime 1.

96105255

A fundamental lnvestlgatlon

of the flame klnetlcs of

coal pyrite Fate of metal Ions In a brown coal durlng pyrolysls 96105246 at low temperatures

Li, C. Z. et al., Coal Sci. Technol., 1995, 1, 683-686. Presents study of the fate of the organically bound metal ions in a set of brown coal samples during pyrolysis at 600-1000°C. 96105247

Flame stablllzatlon

by pulverized coal preheating In

flnlte space

Han, C. er al., Ranshao Kexue Yu Jishu, 1995, 1, (1), 27-33. (In Chinese) Describes how pulverized coal is preheated in finite space but not burnt, so that pulverized’coal flame is stabilized without slagging. In accordance with the idea, a burner with a flame holder is designed. Cold and hot modelling tests showed that not only the velocity distribution, particle concentration distribution, but also temperature distribution, were favourable for the preheating of pulverized coal and slag is avoided. 96105246 Flash pyrolysls end gaseous hydrocarbons.

of brown coal for obtalnlng liquid Ill. Effect of gas residence time

Zhu, Z. et al., Huagong Xuebao (China. Ed), 1995, 46, (6), 710-716. (In Chinese) Flash hydropyolysis of Zalannoer brown coal (Inner Mongolia) was carried out in an experimental entrained-bed reactor.

Ten Brink, H. M. er al., Fuel, Jun. 1996, 75, (8), 945-951. The kinetics of the transformations which pyrite (Fe!&) particles undergo in coal flames were studied in a laboratory burner. The size of the particles leaving the burner was measured with an optical sizer and the composition of the sampled particles was analysed by computer-controlled scanning electron microscopy. The pyrite particles decomposed into pyrrhotite (FeS) in a time corresponding to that required to transfer the necdssary heat from the gas to the particles to sustain the endothermic decomposition reaction. There were no further reactions in a reducing flame, only rapid melting. In an oxidizing flame, decomposition and melting occurred prior to oxidation.

General flame-propa atlon model for fuel droplet, particle and vapour mlxtures In aPr

96105256

Gauthier, J. E. ef al., J. Inst. of Energy, Jun. 1996, 69, (479), 59-67. The paper presents a simple phenomenological model that offers a consistent method of computing the burning velocity in each of the three regimes. The effects of turbulence can be allowed for. The model can be used with multi-component fuels in conjunction with techniques that have been developed to predict instantaneous properties of vaporising petroleum fractions. The simplicity of the model makes it amenable to inclusion as a submodel in larger models used for the design of practical combustion systems.

96105249

Flash yrolysls of hydroxyl-terminated polybutadlene (HTPB) II. Pmpllcatlons of the klnetlcs to combustlon of organic polymers Arisawa, H. and Brill, T. B. Combustion & Flame, Jul. 1996, 106, (1), 144-154. The &t-semi-micro kinetics analysis is described for rapid pyrolysis of an organic polymer. T-Jum /FTlR spectroscopy and structurally different hydroxyl-terminated poly g utadlene polymers were used. 96105250

polybutadlene ous products

Flash ovrolvsls of hvdroxvl-terminated (HTPB). I. ‘%alysls and lmpllc&lons of the gase-

Arisawa, H. and Brill, T. B. Combustion & Flame, Jul. 1996, 106, (l), 131-143. Flash pyrolysis of structurally different hydroxyl-terminated polybutadiene polymers (HTPB) was calculated at 6OO”C/s to constant temperatures in the 450”-609°C range under 2 and 11 atm of applied pressure. T-JumpiFTIR spectroscopy was used. With chemometric @oced;res based on the entire mid-IR spectrum, 13 gaseous products representing at least 70% of the polymer were identified and quantified.

96105251 Flashchaln theory for rapld coal devolatlllzatlon klnetlcs. 7. Predlctlng the release of oxygen species from varlous coals Niksa, S. Energy Fuels, 1996, 10, (l), 173-187. The release of oxygen from any coal primarily involves only three mechanisms: the shuttling of oxygen as an element in tar molecules; the simultaneous release of CO,. H,O. and small amounts of CO when labile bridges are converted into Lhar&links: and the release of CO from the resid;al oxygen in nascent char links’at high tempeatures. This modelling study characterizes these processes for heating rates from 0.5 to lo* K/s, temperatures to 1550 K, and pressures from 0.1 to 1 MPa. 96105252

Formation

of HNCO from the rapld pyrolysls

of

coals Nelson, P. F. et al., Energy Fuels, 1996, 10, (1), 264-265. For a wide range of coal types and pyrolysis temperatures HNCO was observed in the gas phase products. For the conditions tested, HNCO represents some 15% of the eas ohase N soecies. with HCN and NH, accountine for some 40 and 45%, &p&tively. i‘his esiimation is based o/calibrations developed during recent previous FTIR observations of NHCO produced from interactions between propane and NO and from CO&/NO mixtures passed over car exhaust type catalyst. Hence HNCO is not insignificant nitrogen-containing constituent of the products of coal pyrolysis. 96105253

Forward smolder of polyurethane

foam In a forced

alr flow

Torero, J. L. and Fernandez-Pello, A. C. Combustion & Flame, Jul. 1996, 106, (l), 89-109. An experimental study is conducted of forward smolder of polyurethane foam. Air is used to oxidizer, and is forced in the direction of smolder propagation under conditions that produce approximately one-dimensional forward smolder propagation. The objective of the study is to provide further understanding of the mechanisms controlling forward smolder and verification of theoretical models of the problem.

366

Fuel and Energy Abstracts

September 1996

96105257 Heating and I nltlon of combustible dust layers on a hot surface: Influence o9 layer shrlnkage Kim, H. M. and Hwang, C. C. Combustion & Flame, Jun. 1996, 105, (4), It_), “OC “‘-‘oJ’ A combustible dust layer on a hot surface may ignite if the temperature is sufficiently high. Based on experimental observations, a model is developed to incude the layer shrinkage as the combustible material is consumed in the process of heating that may lead to ignition. During the pyrolysis, the packed dust layer shrinks as a result of a variation of the particle size. The ‘transient heat conduction equation with temperature-depkndent distributed heat sources is solved numerically. Thermal conductivity equations developed by previous workers for granular materials is employed in the present analysis. The effect of the layer shrinkage on the dust-layer temperature distribution and ensuing ignition is computed for various layer parameters.

Ignltlon and combustion of laser-heated pulverlred 2:$5258 Ou. M. et al.. Fuel. Aue. 1996. 75. (101. 1155-1160. Thk tempera&e change i’; coal and giapkite during heating and combustion by a CO, laser heat source was measured using the multi-two-colour method. Laser intensity ranging up to 3.0 W mm1.2 at 10.6 urn wavelength was used. The behaviour of heating particles was observed with a stereomicroscope. Graphite particles and several types of coal were used to cover the range of volatile matter from 0 to 43.3 wt%. Experiments were performed to study the influence of volatile matter, particle diameter, oxygen content in the atmosphere and laser intensity on each type of carbon particle. Volatile matter affected the initial heating stage and the ignition stage. Particle diameter had no observable effect at any stage.

96105259 lgnltlon mechanisms of dlfferent ranks of coal Chen, Y. et al., Coal Sci. Tzchnol., 1995, 24, (l), 603.606. Describes how as coal rank increases from lignite through bituminous to anthracite, its ignition mechanism changes from homogeneous through homogeneous-heterogeneous to heterogeneous.

96105260 lgnltlon of coal particles Manzanares, P. L. er al., Coal Sci. Technol., 1995, 24, (l), 587-590. Discusses the study of the effects of coal particle size and mineral and maceral compositions on coal ignition.

96/05261 An Improved model for flxed-bed coal combustion and gaslflcatlon: sensltlvlty analysis and appllcatlons Ghani, M. U. ef al., Fuel, Aug. 1996, 75, (lo), 1213-1226. Detailed sensitivity analysis and applications of an improved, comprehensive, one-dimensional model for combustion and gasification of coal in fixed beds, FBED-1, are presented. The effects of the devolatilization, oxidation and gasification submodels on the model predictions are discussed. The product gas compositions predicted by various options for gasphase chemistry are shown. The effects of five model parameters and one operational variable on the predictions of the model are also presented.