Low-temperature oxidation of coal. 3. Modelling spontaneous combustion of coal stockpiles

Krishnaswamy, Srinivas

doi:10.1016/0140-6701(96)88397-4

Cited by 17 publications

(24 citation statements)

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“…In this study, the gas flow in the reactor vessel was managed as laminar flow in porous media. Because the diameter of fine particles of coal is quite small (the average diameter is about 0.24 mm), the characteristics of the gas stream inside the pile of coal fineparticles can be represented using Darcy's law (Brooks et al, 1988;Salinger et al, 1994;Krishnaswamy et al, 1996;Moghtaderi et al, 2000;Akgun & Essenhigh, 2001). The spontaneous combustion of coal was simulated as a reaction of surface chemicals in which the oxidation reaction appeared on the surface of coal in the porous media.…”

Section: Coal Properties and Coal-pile Permeabilitymentioning

confidence: 99%

“…In an investigation of the safety of coal during storage and transport, it is desirable to model the spontaneous combustion phenomenon in greater detail based on their physical and chemistry properties (Salinger et al, 1994;Krishnaswamy et al, 1996;Akgun & Essenhigh, 2001;Yuan & Smith, 2008). This paper aims to model the CPT phenomenon in low temperature oxidation of coal using COMSOL Multiphysics®.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of the Crossing Point Temperature Phenomenon in the Low-temperature Oxidation of Coal

Saleh¹,

Muharram²,

Nugroho³

2017

IJTech

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In this study, modeling of the crossing point temperature (CPT) phenomenon in the lowtemperature oxidation of coal was carried out using COMSOL Multiphysics®. Lowtemperature oxidation can lead to spontaneous combustion of coal stockpiles. The CPT phenomenon was modeled with the kinetics data obtained from a prior laboratory experimental study. The coupling of the heat-transfer phenomenon through conduction and convection determined the thermal evolution model. In this case, coal received the initial heat of the oven temperature increases. As the coal temperature rose, the heat generated from oxidation was released into the environment via conduction and convection. Meanwhile, oxidation products and oxygen were transferred by convection and diffusion. The effects of moisture and the humidity were not considered. The outcomes of modeling were validated through comparison with the results of experimental tests, and the modeling result agreed well with the experiment tests, with temperature deviations of about 0.9%. The effects of airflow rate, oxygen concentration, porosity, and the initial temperature on low-temperature coal oxidation were also examined.

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Section: Coal Properties and Coal-pile Permeabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling of the Crossing Point Temperature Phenomenon in the Low-temperature Oxidation of Coal

Saleh¹,

Muharram²,

Nugroho³

2017

IJTech

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“…There is quite an extensive literature concerning a mathematical description of spontaneous heating and self ignition of coal. Previous works : Branny M. et al (1995: Branny M. et al ( , 1997Krishnaswamy S.K. et al (1996) ;Rosema A. et al (2001) ;Schmal D. et al (1985); Schmidt M. et al (2003) ;Smith M.A., Glasser D. (2005) were of a cognitive nature and intended to explain the mechanism of spontaneous combustion.…”

Section: Introductionmentioning

confidence: 99%

Determination of Critical Conditions of Spontaneous Combustion of Coal in Longwall Gob Areas / Wyznaczanie Warunków Krytycznych Samozapalania Węgla W Zrobach Ścian

Cygankiewicz¹

2015

Archives of Mining Sciences

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Decades of experience in the fight against endogenous fire hazard in coal mines indicate a major influence of certain conditions in a given area of the mine on the possibility of fire occurrence, such as: susceptibility of coals to spontaneous combustion, oxygen content in the air incoming to the self-heating coal, conditions of heat exchange between the self-heating coal mass and the environment This paper presents a numerical method for determining the critical conditions of spontaneous combustion of coal in longwall gob areas, i.e. conditions under which spontaneous combustion may occur. It has been assumed that crushed coal in the gob has a shape of a flat layer adjacent from the roof and floor side to the rocks.Our considerations have been limited to coals containing small amount of moisture. A simple model of oxidation kinetics on the coal surface expressed by the Arrhenius equation has been adopted. This model assumes that oxidation rate is independent of the amount of oxygen absorbed by coal. The rate of reaction depends only on temperature, with the parameters of the equation changing after the coal has reached the critical temperature.The article presents also a mathematical model of spontaneous heating of the coal layer in the gob area. It describes the heat balance in the coal as well as the oxygen and heat balance in the flowing gases. The model consists of a system of differential equations which are solved using numerical techniques. The developed computer program enables to perform the relevant calculations.In this paper, on the example of coal from a seam 405, we present the method for determining the following critical parameters of the layer of crushed coal: thickness of the layer, oxygen content in a stream of gases flowing through the layer and thermal conductivity of surrounding rocks. Keywords 762Wieloletnie doświadczenie w zakresie zwalczania zagrożenia pożarem endogenicznym w kopalniach wskazują na zasadniczy wpływ na możliwość zaistnienia pożaru niektórych warunków panujących w danym miejscu kopalni, takich jak:-skłonność węgla do samozapalania -zawartość tlenu w powietrzu dopływającym do zagrzewającego się węgla. W pracy przedstawiono numeryczną metodę wyznaczania warunków krytycznych samozapalania węgla w zrobach ścian, czyli takich po spełnieniu których może dojść do samozapalenia. Przyjęto, że znajdujący się w zrobach rozkruszony węgiel ma kształt płaskiej warstwy, sąsiadującej od stropu i spągu ze skałami.Rozważania ograniczono do węgli charakteryzujących się niską zawartością wilgoci. Przyjęto prosty model kinetyki utleniania na powierzchni węgla wyrażony równaniem Arrheniusa. Model ten zakłada niezależność szybkości utleniania od ilości tlenu pochłoniętego przez węgiel. Szybkość reakcji zależy jedynie od temperatury , przy czym występujące w równaniu parametry zmieniają się po osiągnięciu przez węgiel temperatury krytycznej. W artykule przedstawiono matematyczny model samozagrzewania warstwy węgla w zrobach opisujący bilans ciepła w węglu oraz bilans tlenu i bilans ciepła w prze...

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“…Previously, much experimental and theoretical effort [1][2][3][4][5][6][7][8] has been devoted to this area. In particular, theoretical research has been of a major focus, aiming at development of theoretical tools for prediction of spontaneous ignition.…”

Section: Introductionmentioning

confidence: 99%

“…In [3], numerical calculation was performed to study coal stockpile's self-ignition in a confined space based on a one-dimensional diffusion model. A two-dimensional calculation with inclusion of convection was carried out in [4] to examine the spontaneous ignition of open coal stockpile. In these two computations, the moisture effect was assumed to be unimportant.…”

Section: Introductionmentioning

confidence: 99%

Validation Of CFD Model For Simulation Of Spontaneous Ignition In Bio-mass Fuel Storage

Yan¹,

Blomqvist

Göransson

et al. 2005

Fire Safety Science - Proceedings of the Eigth International Sy

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Both numerical simulations and experimental measurements of small scale spontaneous ignition with different biomass fuels have been performed. In the experiments, temperature history was monitored at five different locations inside the fuel bed. The measured temperature history was used for validation of comprehensive threedimensional computer simulations which were carried out using a parallel finite volume CFD code SMAFS (Smoke Movement and Flame Spread) developed by the first author.The computation was based on numerical solution of a set of governing equations including the continuity equation, extended Darcy momentum equations, energy conservation equations for both gas and solid phases, and mass conservation equations for different chemical species. Consideration was given to a series of essential physical and chemical processes, including convection and diffusion in porous media, evaporation, condensation and heat generation which is mainly due to chemical oxidation. With reliable material properties input data provided by separate measurements, it simulated the temporal state evolution inside the biomass fuel storage. Numerical results were compared with experimental measurements, showing excellent agreement.

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Low-temperature oxidation of coal. 3. Modelling spontaneous combustion of coal stockpiles

Cited by 17 publications

References 0 publications

Modeling of the Crossing Point Temperature Phenomenon in the Low-temperature Oxidation of Coal

Modeling of the Crossing Point Temperature Phenomenon in the Low-temperature Oxidation of Coal

Determination of Critical Conditions of Spontaneous Combustion of Coal in Longwall Gob Areas / Wyznaczanie Warunków Krytycznych Samozapalania Węgla W Zrobach Ścian

Validation Of CFD Model For Simulation Of Spontaneous Ignition In Bio-mass Fuel Storage

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