Upper flammability limits of coal dust-AIR mixtures

Deguingand, B.; Galant, S.

doi:10.1016/s0082-0784(81)80075-6

Cited by 7 publications

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“…Results also imply that the lean flammability limit decreases with decreasing particle size_ While the laminar flame propagation data do not provide precise values for flammability limits, results do generally agree with more recent and more specific measurements from the u.s. Bureau of Mines (Hertzberg ef ai., 1982) in the modified Hartmann apparatus, shown in Figure 5,19 for the same coal. The more precise Bureau of Mines results show an independence of the lean-flammability-limit dust concentration on particle size, which differs somewhat from the implications of Figure 5,18_ However, the magnitude of the lean limit in air (135 g/ m 3 ), the absence of a practical rich limit, and maximum particle size for which a coal dust air flame can be stabilized (about 50 /-t m) are similar in the two sets of test results, Deguingand and Galant (1980) recently reported an upper flammability limit (from 8-liter chamberl for a high-volatile (35 % proximate) bituminous coal of abo ut 3900 g of coal per cubic meters of air (3,9 kg of coal per kilogram of air) with a weak dependence on particle size, This value is about 30 times the overall stoichiometric value for the coal and confirms the absence of any practical upper flammability limit. Flammability limits and flame propagation velocities are also influenced by addition of gaseous fuel, as illustrated in Figure 5,20, These data are for flames ., with and without 2% (volume) of CH" in air for Pittsburgh bituminous coal dust .…”

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confidence: 54%

Coal Combustion and Gasification

1985

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This limited facsimile edition has been issued for the purpose of keeping this title available to the scientific community. © 1985 Springer Science+Business Media New York Originally published by Plcnum Press, New York in 1985 Softcover reprint of the hardcover Ist edition 1985 AII rights reservedNo part of this book may bc reproduced, storcd in a retrieval system, or transmittcd in any form or by any means, electronic, mechanical, photocopying, microfilming.recording, or othcrwise, without written permission irom the Publisher · .. II, that r",weth light, and cont",,,,th In C",/, re",vtlh mort bght: and that bght grou,tlh brighter and brighter .. Doctrine and Covenants 50:24 DEDICATIONRecognizing its several limitations, we unpretentiously dedicate this book to our Creator, Who, through holy writ, has inspired us to seek light and understanding where darkness exists, and Who, through these same records, has taught us to place our professional pursuits in perspective with greater obligations of service to family and to society. PREFACE ix 4. Chapters 9, 10, and 14 provide the fundamental equations and background for turbulent combustion systems. 5. Chapters 11-13 and 15 document in some detail the approach and theory for the interactions between chemistry and turbulence in reacting systems encompassing gaseous flames, particle-laden systems, and pollutant formation in these systems.This work has formed the basis for model development at our Combustion Laboratory. These fundamentals were treated generally in the first book. The treatment in this new book for governing equations and for radiation is not greatly changed. However, significant new material is added for chemically reacting, turbulent, heterogeneous systems and for formation of nitrogen oxide pollutants. Included in several of these chapters are comparisons of measurements with predictions from a comprehensive model developed at the Combustion Laboratory. These comparisons demonstrate the state of development of the comprehensive code which, in the view of the authors, is suitable for some practical application to pulverized-coal systems. While this method has been developed principally for pulverized-coal combustion and gasification, this and similar methods have far more general applicability. The code is directly applicable to nonreactive gaseous and particle-laden flows and to reactive gaseous systems. Progress is being made for application to coal slurries and only minor work would be required for use with liquid fuel flames.The authors recognize the several uncertainties in constructing and applying models of this nature. Coal is a very complex heterogeneous substance whose structure and behavior are highly variable and are not well known. Pyrolysis and oxidation of coal are dependent upon coal type, size, size distribution, temperature history, etc., thus making generalization difficult. In addition, the complexities of turbulent recirculating flows, turbulent reacting flows, and turbulent two-phase flows are not fully resolved. Only recently ...

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confidence: 54%

Coal Combustion and Gasification

1985

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“…It was also observed that coal and biomass fuels have no upper flammability limit. Deguingand & Galant [22] employed weak spark ignition for the determination of the upper flammable limit and found apparent upper flammable limit of coal dust to be ~ 4 kg/m 3 , which is more an ignitability limit rather than a flammability limit because of the weak ignition source.…”

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confidence: 99%

Global kinetics of the rate of volatile release from biomasses in comparison to coal

Saeed

Andrews

Phylaktou

et al. 2016

Fuel

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The chemistry involved in the propagation of pulverised biomass flames is not well understood. All biomass fuels release volatiles at a much lower temperature than coal and the proportion of volatiles is much greater than for coal, typically 80% compared to 30%. Thus, the rate of release of volatiles from biomass fuels is much more important in the pulverised fuel flame propagation than it is for coal, where the rate of char There is currently little understanding of the composition of the volatiles released at low temperatures from biomass, as most publications are for pyrolysis conditions at high temperature. It is possible that the volatiles are a mixture of mainly H2, CO and CH4 and the likely proportions of these were calculated from the elemental and thermo-gravimetric analysis. This was done for a range of biomasses and this showed that the most important volatile gas is likely to be CO and that CH4 yield is very low. This means that the conventional model used in coal combustion of char plus methane combustion is not applicable to biomass combustion.

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2012

Lees' Loss Prevention in the Process Industries

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Upper flammability limits of coal dust-AIR mixtures

Cited by 7 publications

References 3 publications

Coal Combustion and Gasification

Coal Combustion and Gasification

Global kinetics of the rate of volatile release from biomasses in comparison to coal

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