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Ignition and combustion of coal particle streams
09 95102072 Flame propagatlon through perlodlc vortices Dold, J. W. et al., C&&S&I & Flame, Feb: 1995, 100, (3), 359-366. The discovery of a new class of Navier-Stokes solutions representing steady periodic stretched vortices offers a useful test-bed for examining interactions between flames and complex flow-fields. After briefly describing these vortex solutions and their wide-ranging parameterisation in terms of wavelength and amplitude, this article examines their effect on flames of constant normal propagation speed as observed through numerical solutions of an eikonal equation. Over certain ranges of vortex amplitude and flame-speed, a corridor of enhanced flame passage is seen to be created as a leading flame-tip manages to leap-frog between successive vortices. However,for large enough amplitudes of vorticity or small enou h flamespeeds, the flame fails to be able to benefit from the advection d ue to the vortices.
Flame spread over thln aolld fuela In partially premlxed atmospheres Ronney, P. D. et al., Combustion & Flame, Feb. 1995,100, (3), 474-484.
95/02873
Experiments on flame spread rates (S,) over thin solid fuels in oxidizing atmospheres to which gaseous fuel is added reveal a large increase in S, for some gaseous fuels. The most to least effective fuels tested are, in order, H,, CO, hydrocarbons, and NH,. From these experiments it is inferred that, unlike nonpremixed flame spread, the finite-rate kinetics of the gaseous fuel have a dominant influence on S, even far from extinction conditions. A simple model developed to account for the effect of the gaseous fuel on S,, while still retaining the framework of deRis’s model of S, for infinite-rate kinetics of the solid fuel vapours, shows good qualitative and fair quantitative agreement with experimental data.
Fundamental combuatlon research In support of Industrial appllcatlona Penner, S. S. and Berlad, A. L. Energy, Apr. 1995, 20, (4), 311-324.
95lO2074
A Workshop was organized for the purpose -of receiving expert inputs on basic research in support of industrial applications of combustion systems. The output of this Workshop is summarized in this paper.
Heat release tlmlng In a nonpremlxed Helmholtz pulse combuator Tang, Y. M. et aZ., Combustion & Flame, Jan. 1995, 100, (l), 251-261.
Combustion (burners, combustion systems)
95lO2079 An improved model for flxed bed coal combustion and gaaltlcatlon Radulovic, P. T. et aL, FueL Apr. 1995. 74, (4). 582-594. An improved one-dimehsional.mddel for &unie&rrent oxidation and gasification of coal in fixed or slow1 moving beds has been developed. The model incorporates an advanced Bevolatiliiation submodel that can predict the evolution rates and the yields of individual gas species and tar. A split, back-and-forth, shooting method is implemented to satisfy exactly the boundary conditions for both the feed coal and the feed gas streams. An option to switch between equilibrium and non-equilibrium gas phase composition has been added. The model yields improved predictions for product gas composition and product tar flow rate. The model predictions are compared with the expenmental data for two coals: a Jetson bituminous coal and a Rosebud subbituminous coal.
Influence of pulverlzed coal characterlatlca on ths 95lQ2000 mlcroatructure and combuatlon property of char partlcles Xu, W. and Du, H. Gangtie Yanjiu Xuebao, 1994,6, (3), l-5. (In Chinese) Discusss the effect of porous structure of char particles of bituminous and anthracite on combustion.
coal
Klnetlc Interactions of CO, NO,, and HCI emlsslona In poatcombustlon gases Roesler, J. F. et al., Combustion & Flame, Feb. 1995, 100, (3), 495-504.
95/02001
Postflame chemistry is governed largely by moist CO oxidation. During carbon monoxide burnout, trace amounts of many other pollutants formed in and/or surviving through the flame front may be present (e.g. SO,, NO,, HCl, and unburned hydrocarbons). The development of accurate chemical models describing these final stages of pollutant destruction requires evaluating the potentia kinetic couplrng effkcts that exist among &ese components. In the present investigation, the coupling between NO and HCl in a moist CO oxidation bath is considered.
Klnetlca of coal pyrolyala 95102002 Yao, 2. and Han, Y. Mei Huagong, 1994, (2), 34-40. (In Chinese) Discusses the kinetics of pyrolysis of various rank coals using thermogravimetry.
95102075
The paper discusses the mechanism by which heat release fluctuations drive pressure pulsations in Helmholtz pulse combustors with nonpremixed fuel and air injection, similar to those used in commercialized pulse furnaces.
lgnltlon and combustion of coal particle streams 95102070 Du, X. et al., Fuel, Apr. 1995, 74, (4). 487-494. The paper resents a model for group combustion of a cylindrical stream of coal partic.P es and preliminary experimental data. Results are obtained from transient ignition and combustion behaviour. It is found that homogeneous ignition (ignition of volatiles) occurs for a dense cloud, while heterogeneous ignition (ignition of carbon) occurs for a dilute cloud. Once ignited, the flame moves towards the cloud, reaches the cloud surface and then bifurcates into two flames, called the inner and outer flames. The inner flame propagates into an unburnt volatile-air mixture in the cloud, while the outer diffusion flame moves away from the cloud. The inner flame propagates at the laminar burning velocity and rapidly heats the particles. There is only a diffusion flame o;tside tile cloud- afiir all the oxygen in the cloud- is consumed. Ignition and combustion of Isolated and binary 95102077 array of coal pattlclea Kbarbat, E. et al., Combustion & Flame, Feb. 1995, 100, (3), 413-421.
Klnetlca of the phenyl radical reactlon wlth ethy lene: An RRKM theoretical analyala of low and hlgh temperature data Yu, T. and Lin, M. C. Combustion&Flame, Jan. 1995,100, (l), 169-176.
95iQ2003
Discusses the kinetics of the reaction of phenyl radical with ethylene with the cavity-ring-down method at six temperatures between 297 and 523 K under a constant pressure of 20 ton Ar.
Laboratory atudy of N,O formatlon from burnlng char partlclea at FBC condltlons Miettinen, H. et al., Energy & FueLs, Jan.-Feb. 1995, 9, (1), 10-19.
95/02004
Coal combustion in fluidized bed cornbuster is a cause of nitrous oxide emissions to the atmosphere. The formation of N,O seems to be related both to homogeneous and heterogeneous reactions taking place in the combustion process. The purpose of this investigation was to study the formation of N,O from burning char particles under different combustion conditions. The experiments were carried out in a fixed bed reactor containing quartz sand (SiO,) to support the coal particles.
Laser mlcroprobe analyala of soot precursor pattlclea and carbonaceous soot Dobbins, R. A. et al., Combustion&Flame, Jan. 1995, 100, (l), 301-309. 95102005
Sam les of soot recursor particles and carbonaceous smo Eing ethene g.Iffusion flame have been analyzed microorobe mass snectrometrv.
A digital image processing technique is employed to investigate the ignition and combustion characteristics of isolated coal uarticles as well as the interactive combustion of a binary coal array in lo\; Re flow.
95102000
lgnltlon process of a heated Iron block In hlghpressure oxygen atmosphere Sato, J. et al., Combustion & Flame, Feb. 1995, 100, (3), 376-383.
In this paper the authors explore nonpren%ed turbulent jet flames.
95102070
Ignition process of a heated iron rod in a high pressure oxygen atmos here has been studied exoerimentallv and theoreticallv. A mild steel rod 1! mm in diameter and 50 &m in lengih was used for experiments. The test pieces were heated in an argon atmosphere to prevent the oxidation reaction during the heating stage, and then ejected into the high-pressure oxygen atmosphere. When the heated iron rod was ex osed in the oxygen, the surface temperature increased rapidly, reache B a maximum, and then decreased gradually. If the ignition did not occur, the thick oxide layer was onlv, formed on the surface. If ignition occurred. the convective burninn spots ap eared on the surface after a certain &me from the exposure, increase 8, m these areas, and then covered all of the surface, i.e. continuous combustion occurred.
soot from a nonby means of laser
Laser Raman acatterlng measurements of dlfferentlal molecular diffusion In turbulent nonpremlxed Jet flamea of H&O, fuel Smith, L. L. et al., Combustion & Flame, Jan. 1995, 100, (l)? 153-160. the effects
of differential
chffusion in
Lewis number effects on premlxed flames lnteractIng with turbulent Karman vortex streets Lee, J. G. et aZ., Combustion & Flame, Jan. 1995, 100, (l), 161-168.
95lQ2007
The effects of Lewis number on the global and local structure of premixed flames interacting with turbulent Karman vortex streets are experimentally investigated using OH planar-laser-induced fluorescence. The OH PLIF results show that over the range of Lewis numbers studied, i.e. Le = 0.21, 0.94 and 1.79, the flame area increases and the flame front 1s oriented more randomly as Lewis number decreases, while the flame curvature pdfs are unchanged.
Fuel and Energy Abstracts May 1995 207
Flame spread over thln aolld fuela In partially premlxed atmospheres Ronney, P. D. et al., Combustion & Flame, Feb. 1995,100, (3), 474-484.
95/02873
Experiments on flame spread rates (S,) over thin solid fuels in oxidizing atmospheres to which gaseous fuel is added reveal a large increase in S, for some gaseous fuels. The most to least effective fuels tested are, in order, H,, CO, hydrocarbons, and NH,. From these experiments it is inferred that, unlike nonpremixed flame spread, the finite-rate kinetics of the gaseous fuel have a dominant influence on S, even far from extinction conditions. A simple model developed to account for the effect of the gaseous fuel on S,, while still retaining the framework of deRis’s model of S, for infinite-rate kinetics of the solid fuel vapours, shows good qualitative and fair quantitative agreement with experimental data.
Fundamental combuatlon research In support of Industrial appllcatlona Penner, S. S. and Berlad, A. L. Energy, Apr. 1995, 20, (4), 311-324.
95lO2074
A Workshop was organized for the purpose -of receiving expert inputs on basic research in support of industrial applications of combustion systems. The output of this Workshop is summarized in this paper.
Heat release tlmlng In a nonpremlxed Helmholtz pulse combuator Tang, Y. M. et aZ., Combustion & Flame, Jan. 1995, 100, (l), 251-261.
Combustion (burners, combustion systems)
95lO2079 An improved model for flxed bed coal combustion and gaaltlcatlon Radulovic, P. T. et aL, FueL Apr. 1995. 74, (4). 582-594. An improved one-dimehsional.mddel for &unie&rrent oxidation and gasification of coal in fixed or slow1 moving beds has been developed. The model incorporates an advanced Bevolatiliiation submodel that can predict the evolution rates and the yields of individual gas species and tar. A split, back-and-forth, shooting method is implemented to satisfy exactly the boundary conditions for both the feed coal and the feed gas streams. An option to switch between equilibrium and non-equilibrium gas phase composition has been added. The model yields improved predictions for product gas composition and product tar flow rate. The model predictions are compared with the expenmental data for two coals: a Jetson bituminous coal and a Rosebud subbituminous coal.
Influence of pulverlzed coal characterlatlca on ths 95lQ2000 mlcroatructure and combuatlon property of char partlcles Xu, W. and Du, H. Gangtie Yanjiu Xuebao, 1994,6, (3), l-5. (In Chinese) Discusss the effect of porous structure of char particles of bituminous and anthracite on combustion.
coal
Klnetlc Interactions of CO, NO,, and HCI emlsslona In poatcombustlon gases Roesler, J. F. et al., Combustion & Flame, Feb. 1995, 100, (3), 495-504.
95/02001
Postflame chemistry is governed largely by moist CO oxidation. During carbon monoxide burnout, trace amounts of many other pollutants formed in and/or surviving through the flame front may be present (e.g. SO,, NO,, HCl, and unburned hydrocarbons). The development of accurate chemical models describing these final stages of pollutant destruction requires evaluating the potentia kinetic couplrng effkcts that exist among &ese components. In the present investigation, the coupling between NO and HCl in a moist CO oxidation bath is considered.
Klnetlca of coal pyrolyala 95102002 Yao, 2. and Han, Y. Mei Huagong, 1994, (2), 34-40. (In Chinese) Discusses the kinetics of pyrolysis of various rank coals using thermogravimetry.
95102075
The paper discusses the mechanism by which heat release fluctuations drive pressure pulsations in Helmholtz pulse combustors with nonpremixed fuel and air injection, similar to those used in commercialized pulse furnaces.
lgnltlon and combustion of coal particle streams 95102070 Du, X. et al., Fuel, Apr. 1995, 74, (4). 487-494. The paper resents a model for group combustion of a cylindrical stream of coal partic.P es and preliminary experimental data. Results are obtained from transient ignition and combustion behaviour. It is found that homogeneous ignition (ignition of volatiles) occurs for a dense cloud, while heterogeneous ignition (ignition of carbon) occurs for a dilute cloud. Once ignited, the flame moves towards the cloud, reaches the cloud surface and then bifurcates into two flames, called the inner and outer flames. The inner flame propagates into an unburnt volatile-air mixture in the cloud, while the outer diffusion flame moves away from the cloud. The inner flame propagates at the laminar burning velocity and rapidly heats the particles. There is only a diffusion flame o;tside tile cloud- afiir all the oxygen in the cloud- is consumed. Ignition and combustion of Isolated and binary 95102077 array of coal pattlclea Kbarbat, E. et al., Combustion & Flame, Feb. 1995, 100, (3), 413-421.
Klnetlca of the phenyl radical reactlon wlth ethy lene: An RRKM theoretical analyala of low and hlgh temperature data Yu, T. and Lin, M. C. Combustion&Flame, Jan. 1995,100, (l), 169-176.
95iQ2003
Discusses the kinetics of the reaction of phenyl radical with ethylene with the cavity-ring-down method at six temperatures between 297 and 523 K under a constant pressure of 20 ton Ar.
Laboratory atudy of N,O formatlon from burnlng char partlclea at FBC condltlons Miettinen, H. et al., Energy & FueLs, Jan.-Feb. 1995, 9, (1), 10-19.
95/02004
Coal combustion in fluidized bed cornbuster is a cause of nitrous oxide emissions to the atmosphere. The formation of N,O seems to be related both to homogeneous and heterogeneous reactions taking place in the combustion process. The purpose of this investigation was to study the formation of N,O from burning char particles under different combustion conditions. The experiments were carried out in a fixed bed reactor containing quartz sand (SiO,) to support the coal particles.
Laser mlcroprobe analyala of soot precursor pattlclea and carbonaceous soot Dobbins, R. A. et al., Combustion&Flame, Jan. 1995, 100, (l), 301-309. 95102005
Sam les of soot recursor particles and carbonaceous smo Eing ethene g.Iffusion flame have been analyzed microorobe mass snectrometrv.
A digital image processing technique is employed to investigate the ignition and combustion characteristics of isolated coal uarticles as well as the interactive combustion of a binary coal array in lo\; Re flow.
95102000
lgnltlon process of a heated Iron block In hlghpressure oxygen atmosphere Sato, J. et al., Combustion & Flame, Feb. 1995, 100, (3), 376-383.
In this paper the authors explore nonpren%ed turbulent jet flames.
95102070
Ignition process of a heated iron rod in a high pressure oxygen atmos here has been studied exoerimentallv and theoreticallv. A mild steel rod 1! mm in diameter and 50 &m in lengih was used for experiments. The test pieces were heated in an argon atmosphere to prevent the oxidation reaction during the heating stage, and then ejected into the high-pressure oxygen atmosphere. When the heated iron rod was ex osed in the oxygen, the surface temperature increased rapidly, reache B a maximum, and then decreased gradually. If the ignition did not occur, the thick oxide layer was onlv, formed on the surface. If ignition occurred. the convective burninn spots ap eared on the surface after a certain &me from the exposure, increase 8, m these areas, and then covered all of the surface, i.e. continuous combustion occurred.
soot from a nonby means of laser
Laser Raman acatterlng measurements of dlfferentlal molecular diffusion In turbulent nonpremlxed Jet flamea of H&O, fuel Smith, L. L. et al., Combustion & Flame, Jan. 1995, 100, (l)? 153-160. the effects
of differential
chffusion in
Lewis number effects on premlxed flames lnteractIng with turbulent Karman vortex streets Lee, J. G. et aZ., Combustion & Flame, Jan. 1995, 100, (l), 161-168.
95lQ2007
The effects of Lewis number on the global and local structure of premixed flames interacting with turbulent Karman vortex streets are experimentally investigated using OH planar-laser-induced fluorescence. The OH PLIF results show that over the range of Lewis numbers studied, i.e. Le = 0.21, 0.94 and 1.79, the flame area increases and the flame front 1s oriented more randomly as Lewis number decreases, while the flame curvature pdfs are unchanged.
Fuel and Energy Abstracts May 1995 207