Effect of sodium on deposition in a simulated combustion gas turbine environment

Ross, Jeffrey S.; Anderson, Rodney J.; Nagarajan, R.

doi:10.1021/ef00009a010

Cited by 20 publications

(12 citation statements)

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“…In view of the hypothesis that the condensed liquid plays an important role in the process of ash adhesion, it is reasonable to expect that this same ordering will prevail when comparing the coals with respect to their sticking propensity. However, as was shown in Ross et al (1987a), while the extremes match--i.e., NDL and BJB coals have the largest and smallest ash-sticking coefficients respectively--the correlation fails to hold for intermediate sticking coefficients. For instance, at 1100K, experimentally-obtained atmospheric-pressure sticking coefficients for the coals were in the order: NDL > SCMS > APB > KB, whereas PACKAGE-predicted liquid phase fractions line up as: NDL > APB > SCMS > KB.…”

Section: Thermodynamic Prediction Of Condensed Phase Compositionmentioning

confidence: 64%

“…Time-resolved measurements of target metal temperature in an atmospheric-pressure test reactor at METC have been found to agree reasonably well with corresponding theoretical predictions. Ross et al (1987a) have also studied the effect of gas phase alkali concentration on the adhesion properties of micronized coal by seeding the coal with excess alkali. Laboratory measurements of sticking coefficients in the (initial) clean target surface temperature regime of 980K-1220K for several naturally-occurring and chemically-doped coals have provided tentative confirmation of the accuracy of our model in predicting ash deposition behavior in this _temperature regime.…”

Section: Diffusionally Deposited Gluementioning

confidence: 99%

“…Among the solids predicted to precipitate out are Al2SiO5 (anhydrous), Al2TiO5 CaAl2Si2O8, Fe2O3, Si02 and CaSO4; these are relatively benign with respect to the ash deposition process. High molecular-weight gas-phase compounds, e.g., Na2Al2Si6O16 suppress liquid condensation by 'trapping' condensible alkalis; this suggests a chemical means (discussed in more detail in Ross et al, 1987a) to mitigatJ deposition by additives.…”

Section: Thermodynamic Prediction Of Condensed Phase Compositionmentioning

confidence: 99%

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Effect of Coal Constituents on the Liquid-Assisted Capture of Impacting Ash Particles in Direct Coal-Fired Gas Turbines

Nagarajan

Anderson²

1988

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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With the growing interest in burning pulverized coal directly in gas turbines, the problem of fouling — blockage of hot-gas pathways by thick ash deposits — is receiving increased attention. The inertial deposition rate of supermicron ash, which determines the fouling propensity of the coal via the thickness of the deposit, depends linearly on the sticking fraction of ash material arriving at the cooled surfaces, e.g., turbine blades and guide vanes. The magnitude and temperature-dependence of the sticking coefficient will depend on the inventory, composition and physicochemical properties of the liquid ‘glue’ consistent with the prevailing temperature, pressure and trace inorganic elemental compositions. As the deposit evolves in time, it encounters several deposition regimes in the order of increasing surface temperature, each characterized by a different source of liquid glue. The effect of coal-ash constituents on the extent of each of these sticking regimes is investigated theoretically here by means of a model of ‘self-regulated’ ash deposition.

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Section: Thermodynamic Prediction Of Condensed Phase Compositionmentioning

confidence: 64%

Section: Diffusionally Deposited Gluementioning

confidence: 99%

Section: Thermodynamic Prediction Of Condensed Phase Compositionmentioning

confidence: 99%

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Effect of Coal Constituents on the Liquid-Assisted Capture of Impacting Ash Particles in Direct Coal-Fired Gas Turbines

Nagarajan

Anderson²

1988

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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“…In addition, the amount of molten ash particles significantly contributes to the evaluation of the stickiness. 134 Whether the prediction of ash deposition using melt fraction models can be more accurate than the viscosity-based models at high temperatures has been debatable. 135 Hansen et al 136 suggested that the particle sticking probability increases proportionally to the number of molten ash particles deposited on the heat transfer surfaces.…”

Section: Particle Impaction Modelmentioning

confidence: 99%

“…In addition, the amount of molten ash particles significantly contributes to the evaluation of the stickiness . Whether the prediction of ash deposition using melt fraction models can be more accurate than the viscosity-based models at high temperatures has been debatable .…”

Section: Cfd Modeling Of Ash Depositionmentioning

confidence: 99%

A Review of the Numerical Modeling of Pulverized Coal Combustion for High-Efficiency, Low-Emissions (HELE) Power Generation

et al. 2021

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High-efficiency, low-emissions (HELE) coal-fired power plant technologies operate with a higher thermal efficiency of the steam cycle for coal-fired power generation, reducing CO2 emissions per unit energy generation. They represent some of the primary and intermediate solutions to the world’s energy security. Extensive numerical modeling efforts have been undertaken over the past several decades, which have increased our understanding of the technical problems in HELE boilers, including combustion and boiler performance optimization, ash deposition, and material problems at higher operating temperatures and pressures. Overall, the differences in the physical and chemical models, boiler performance, and ash deposition of oxy-fuel combustion in HELE boilers that recirculate CO2 and H2O in the boilers are also discussed in comparison with the combustion of coal in the air. This Review comprehensively summarizes the current research on numerical modeling to offer a better understanding of the technical aspects and provides future research requirements of HELE coal-fired boilers, including boiler performance optimization, ash deposition, and material problems. The effects of changes in the configuration and operating conditions are discussed, focusing on the optimization of boiler performance in aspects such as unburnt carbon and NOx emissions. The paper also reviews the retrofit and optimization of operating conditions and the burner geometry with the low-NOx coal combustion technologies necessary to operate the HELE power plants. In terms of ash deposition, the development of submodels, including particle sticking and impacting behaviors and their effects on the deposit growth predictions under different temperatures, are discussed. Numerical models of the material oxidation and creep in the austenitic and nickel-based alloys generally used in HELE conditions have been developed using the finite element method to predict the availability of advanced alloys and creep life in the actual service time of the boiler parts. The predictions of oxide scale growth and exfoliation on the steam-side and fire-side and the creep strength are analyzed. The review also identifies some further research requirements in numerical modeling to achieve the optimization of coal combustion processes and address the technical problems in advanced HELE power plant operations.

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Adhesion of Ash Particles on Heat Transfer Surfaces in Coal Combustion Applications: Mechanisms and Implications

Nagarajan

1989

Particles on Surfaces 2

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Effect of sodium on deposition in a simulated combustion gas turbine environment

Cited by 20 publications

References 1 publication

Effect of Coal Constituents on the Liquid-Assisted Capture of Impacting Ash Particles in Direct Coal-Fired Gas Turbines

Effect of Coal Constituents on the Liquid-Assisted Capture of Impacting Ash Particles in Direct Coal-Fired Gas Turbines

A Review of the Numerical Modeling of Pulverized Coal Combustion for High-Efficiency, Low-Emissions (HELE) Power Generation

Adhesion of Ash Particles on Heat Transfer Surfaces in Coal Combustion Applications: Mechanisms and Implications

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