Prediction of fly ash size and chemical composition distributions: The random coalescence model

Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health

“…109,115 If such information is not available, an approximate distribution can be obtained by assuming that the minerals are randomly distributed between coal particles. [116][117][118][119] The ash particles will have a particle-to-particle variation in composition that will reflect the variation in the mineral content of the individual coal particles from which they are produced. This is illustrated in Figures 6 and 7, which show the Al, Si, and Fe distributions both in the parent coal minerals and in the resulting fly ash, respectively.…”

Submicrometer Particle Formation and Control in a Bench-Scale Pulverized Coal Combustor

“…Such observations have motivated several studies aimed at understanding the mechanisms of submicrometer particle formation during coal combustion. The results of field- and laboratory-scale studies on emissions from pulverized coal combustors indicate that the particle size distributions are typically bimodal. ,− The coarse particle (or residual ash) is formed by the coalescence of mineral inclusions in parent coal particles during the combustion process as described by Flagan, Kang et al., Kang et al, and Barta et al The fine particle mode around 0.1 μm is formed via nucleation of vaporized ash components and growth by coagulation and heterogeneous condensation. , Flagan 13 proposed that certain species might vaporize in the form of suboxides, which are more volatile than the corresponding refractory oxides. Linak and Peterson 11 studied the effects of coal type and residence time on particle size distributions, and concluded that the accumulation of particles in the submicrometer size ranges was the result of vaporization, nucleation, condensation, and coagulation.…”

Improved numerical prediction of ash formation and deposition using a novel developed char fragmentation model

“…Using this virtual coal, Barta et al [6] applied the Random Coalescence Model to statistically calculate the size distribution and the chemical composition of the fly ash. Details on both models can be found in their publications.…”

“…Also Yamashita et al [10] published an ash evolution model based on the approach of [5,6]. For the internal minerals, coalescence was assumed, whereas for the external minerals fragmetation was expected.…”