Ignition and devolatilization of pulverized bituminous coal particles during oxygen/carbon dioxide coal combustion

Abstract Oxygen/carbon dioxide recycle coal combustion is actively being investigated because of its potential to facilitate CO 2 sequestration and to achieve emission reductions. In the work reported here, the effect of enhanced oxygen levels and CO 2 bath gas is independently analyzed for their influence on single-particle pulverized coal ignition of a U.S. eastern bituminous coal. The experiments show that the presence of CO 2 and a lower O 2 concentration increase the ignition delay time but have no measurable effect on the time required to complete volatile combustion, once initiated. For the ignition process observed in the experiments, the CO 2 results are explained by its higher molar specific heat and the O 2 results are explained by the effect of O 2 concentration on the local mixture reactivity. Particle ignition and devolatilization properties in a mixture of 30% O 2 in CO 2 are very similar to those in air.

[1]  R. Essenhigh,et al.  Ignition of coal particles: A review , 1989 .

[2]  B. M. Gibbs,et al.  Pulverized coal combustion in air and in O2/CO2 mixtures with NOx recycle , 2005 .

[3]  B. M. Gibbs,et al.  Comparisons of pulverized coal combustion in air and in mixtures of O2/CO2 , 2005 .

[4]  L. Blevins,et al.  The effect of potassium bromide and sodium carbonate on coal char combustion reactivity , 2003 .

[5]  W. Prins,et al.  Devolatilization and ignition of coal particles in a two-dimensional fluidized bed , 1987 .

[6]  P. Durbetaki,et al.  High-energy Nd-yag laser ignition of coals: Modeling analysis , 1993 .

[7]  J. Howard,et al.  Mechanism of solid-partical combustion with simultaneous gas-phase volatiles combustion , 1967 .

[8]  RajenderKumar Gupta,et al.  Oxy-fuel combustion technology for coal-fired power generation , 2005 .

[9]  Robert W. Schefer,et al.  Flame Sheet Imaging Using CH Chemiluminescence , 1997 .

[10]  John-Chang Chen.  Distributed Activation Energy Model of Heterogeneous Coal Ignition , 1996 .

[11]  J. Pohl,et al.  Direct Observations of Devolatilizing Pulverized Coal Particles in a Combustion Environment , 1981 .

[12]  Takashi Kiga,et al.  Analysis of the flame formed during oxidation of pulverized coal by an O2-CO2 mixture , 1997 .

[13]  K. Annamalai,et al.  The transient ignition of isolated coal particle , 1994 .

[14]  C. Law,et al.  Ignition of counterflowing methane versus heated air under reduced and elevated pressures , 1997 .

[15]  Thomas H. Fletcher,et al.  Time-Resolved Temperature Measurements of Individual Coal Particles During Devolatilization , 1989 .

[16]  W. Fu,et al.  A universal correlation between the heterogeneous ignition temperatures of coal char particles and coals , 1992 .

[17]  K. R. Hencken,et al.  Simultaneous in situ measurement of the size, temperature and velocity of particles in a combustion environment , 1985 .