Numerical study on effects of coal properties on spontaneous heating in longwall gob areas

A computational fluid dynamics (CFD) study was conducted to model effects of coal properties on the potential for spontaneous heating in longwall gob (mined-out) areas. A two longwall panel district using a bleeder ventilation system was simulated. The permeability and porosity profiles for the longwall gob were generated from a geotechnical model and were used as inputs for the three-dimensional CFD modeling. The spontaneous heating is modeled as the low-temperature oxidation of coal in the gob using kinetic data obtained from previous laboratory-scale spontaneous combustion studies. Heat generated from coal oxidation is dissipated by convection and conduction, while oxygen and oxidation products are transported by convection and diffusion. Unsteady state simulations were conducted for three different US coals and simulation results were compared with some available test results. The effects of coal surface area and heat of reaction on the spontaneous heating process were also examined.

[1]  David Glasser,et al.  A simplified model of spontaneous combustion in coal stockpiles , 1986 .

[2]  P. Nordon,et al.  A model for the self-heating reaction of coal and char , 1979 .

[3]  A. Rosema,et al.  Simulation of spontaneous combustion, to study the causes of coal fires in the Rujigou Basin , 2001 .

[4]  John Carras,et al.  Self-heating of coal and related materials: Models, application and test methods , 1994 .

[5]  G. Esterhuizen,et al.  A Methodology For Determining Gob Permeability Distributions And Its Application To Reservoir Modeling Of Coal Mine Longwalls , 2007 .

[6]  J. Edwards.  Mathematical Modeling of Spontaneous Heating of a Coalbed , 2010 .

[7]  I Maria,et al.  Analysis of mine fires for all U.S. underground and surface coal mining categories : 1990-1999 , 2004 .

[8]  Ahmet Arisoy,et al.  Effect of particle size on the spontaneous heating of a coal stockpile , 1994 .

[9]  Fehmi Akgün,et al.  Modelling of spontaneous combustion of coal with moisture content included , 1994 .

[10]  C. P. Lazzara,et al.  Spontaneous combustion studies of U.S. coals , 1987 .

[11]  J. Duyzer,et al.  A model for the spontaneous heating of coal , 1985 .

[12]  Charles P. Lazzara,et al.  Large-scale studies of spontaneous combustion of coal. Rept. of investigations/1991 , 1991 .

[13]  L. D. Schmidt,et al.  Atmospheric Oxidation of Coal at Moderate Temperatures , 1940 .

[14]  Yulianto Sulistyo Nugroho,et al.  Low-temperature oxidation of single and blended coals , 2000 .

[15]  David Glasser,et al.  Spontaneous combustion of carbonaceous stockpiles. Part II. Factors affecting the rate of the low-temperature oxidation reaction , 2005 .

[16]  R. D. Gunn,et al.  Low-temperature oxidation of coal. 3. Modelling spontaneous combustion in coal stockpiles , 1996 .