Coal Ash Deposition on Nozzle Guide Vanes—Part II: Computational Modeling

Barker, B.; Casaday, B.; Shankara, P.; Ameri, Ali; Bons, Jeffrey P.

doi:10.1115/1.4006399

Cited by 50 publications

(43 citation statements)

References 21 publications

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“…24 Therefore, actually, only the medium-sized particles are dominantly captured by the surface. This is confirmed by Barker et al, 23 who predicted higher capture efficiency for medium-sized particles using the critical velocity model. Field observations also show that ash deposit mass is primarily contributed by particles below 30 μm.…”

Section: ■ Discussionsupporting

confidence: 82%

Characterization of Ash Particles from Co-combustion with a Zhundong Coal for Understanding Ash Deposition Behavior

Fan

et al. 2013

Energy Fuels

105

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Co-combustion is the most attractive option for extending the utilization of Zhundong coals from the newly discovered and the largest intact coalfield in China. However, operational practices have shown that power plants frequently encounter ash deposition problems during co-combustion with Zhundong coals. To address such an issue, in the present work, coal blends of a bituminous coal and a Zhundong sub-bituminous coal, with blending ratios of 90:10, 70:30, 50:50, 30:70, and 10:90 on a weight basis, were burned on a laboratory drop tube furnace at 1350°C. For comparison, combustion experiments of the component coals were also carried out under the same conditions. The resulting ash samples were thoroughly characterized by using a Malvern particle size analyzer and a computer controlled scanning electron microscope. The obtained data were correlated to the ash deposition behavior in co-combustion with Zhundong coals in power plant boilers. The results show that particle mass size distributions of the ash samples from combustion of low-ZD-loaded fuels (with the proportion of the Zhundong coal investigated ≤50 wt %) are similar. The basic and acidic elements are partitioned similarly into ash particles. Ash deposition propensities, evaluated as the ratio of basic to acidic oxides (B/A) of the ash, are all low and show insignificant differences. These are consistent with the similarities in ash deposition behavior during co-combustion with Zhundong coals with low proportions in practical coal-fired boilers. In contrast, the ash properties are apparently different for the fuels with the proportion of the Zhundong coal higher than 50 wt % (denoted as high-ZD-loaded fuels). Small particles of <10 μm are more abundant in the ash samples and are more enriched in basic elements (especially Ca, Fe, and Mg) for the high-ZD-loaded fuels than for the low-ZD-loaded fuels. These data could well explain the more serious ash deposition problems arising during cocombustion with higher proportions of the Zhundong coals in practical boilers. It is also found that, for the ashes from combustion of the high-ZD-loaded fuels, both the amount of the small ash particles and the contents of basic elements in them increase with increasing the proportion of the Zhundong coal in the fuel. These data agree well with field observations of higher ash deposition propensities for coal blends with higher proportions of the Zhundong coals.

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Section: ■ Discussionsupporting

confidence: 82%

Characterization of Ash Particles from Co-combustion with a Zhundong Coal for Understanding Ash Deposition Behavior

Fan

et al. 2013

Energy Fuels

105

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“…Owing to higher inertia, larger particles are directed towards the surface with high velocities in comparison to smaller particles [31]. Barker at al [35]. studied coal ash deposition on nozzle guide vanes numerically and validated their simulation results.…”

Section: Resultsmentioning

confidence: 92%

Mechanistic modeling, numerical simulation and validation of slag-layer growth in a coal-fired boiler

Balakrishnan

Nagarajan

Karthick

2015

Energy

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“…The study conducted in [22] utilized and compared both the critical viscosity model as well as the critical velocity model developed by El-Batsh and Haselbacher [14]. While both sticking models showed limitations, the critical viscosity model appeared to be more accurate for a larger range of particle size distributions, and was used in this study.…”

Section: B Critical Viscosity Modelmentioning

confidence: 98%

“…The deposition model is adapted from Barker et al [22], which is a derivative of the Tafti and Sreedharan critical viscosity model [16]. The model was compared to experimental results in Webb et al [23] which found that the model is accurate in predicting initial deposition rates but is not accurate after large-scale deposits are formed.…”

Section: Figure 1 -Volcanic Ash Deposition On Turbine Vanesmentioning

confidence: 99%

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Effect of Hot Streaks on Ash Deposition in an Uncooled Turbine Vane Passage

Casaday

Ameri

Bons

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Coal ash deposition was numerically modeled on an uncooled GE-E 3 high pressure turbine vane passage. A model was developed, in conjunction with Fluent™ software, to track individual particles through the turbine passage. Particles that strike the adiabatic surface become deposits if their viscosity drops below a predetermined value based on temperature. The computational model incorporated non-uniform inlet temperature conditions to account for the existence of a hot streak. The distribution of the temperature non-uniformity affects the location and amount of deposition measured on the nozzle guide vanes. Using a periodic condition that simulates one combustor nozzle per two nozzle guide vanes, the computational model predicts the optimal location for the combustor nozzle location to minimize total deposition rates in the vane passage. The deposition rates are strongly correlated to the average surface temperature of the vanes, but the clocking position with minimum deposition does not correlate to the clocking position with lowest average surface temperatures. The effect of particle size, or Stokes number, on deposition is studied and discussed. Nomenclature A = constant used to define critical viscosity model B = constant used to define critical viscosity model d P = diameter of particle 2 d le = vane leading edge diameter P S = probability of particle sticking St k = Stokes number, T P = temperature of particle V i = Velocity scale in Stokes number equation = capture efficiency = density of particle = viscosity of fluid = viscosity of particle  crit = viscosity of particle at critical sticking temperature

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Coal Ash Deposition on Nozzle Guide Vanes—Part II: Computational Modeling

Cited by 50 publications

References 21 publications

Characterization of Ash Particles from Co-combustion with a Zhundong Coal for Understanding Ash Deposition Behavior

Characterization of Ash Particles from Co-combustion with a Zhundong Coal for Understanding Ash Deposition Behavior

Mechanistic modeling, numerical simulation and validation of slag-layer growth in a coal-fired boiler

Effect of Hot Streaks on Ash Deposition in an Uncooled Turbine Vane Passage

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