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

Balakrishnan, S.; Nagarajan, R.; Karthick, K.

doi:10.1016/j.energy.2014.12.058

Cited by 33 publications

(10 citation statements)

References 34 publications

(50 reference statements)

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“…The simple models mentioned above do not consider particle size or velocity in their sticking criteria and thus may not be widely applicable. Models considering particle or surface properties as well as the size and velocity of the particles to determine sticking or rebound have been developed for impact of elastic–plastic materials, − purely elastic materials, − viscoelastic materials, , and molten materials (droplets). − Some have been applied to ash deposit formation models. ,− , The models generally describe the impact by an energy balance, considering the kinetic energy of the particles, the energy lost by deformation of the particle or surface, the contact area established, and the adhesion energy of the contact area.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Model for Ash Deposit Formation in Biomass Suspension Firing. Part 1: Model Verification by Use of Entrained Flow Reactor Experiments

et al. 2016

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Two models for deposit formation in suspension firing of biomass have been developed. Both models describe deposit buildup by diffusion and subsequent condensation of vapors, thermophoresis of aerosols, convective diffusion of small particles, impaction of large particles, and reaction. The models differ in the description of the sticking probability of impacted particles: model #1 employs a reference viscosity in the description of the sticking probability, while model #2 combines impaction of viscoelastic particles on a solid surface with particle capture by a viscous surface. Both models were used to describe the deposit formation rates and deposit chemistry observed in a series of entrained flow reactor (EFR) experiments using straw and wood as fuels. It was found that model #1 was not able to describe the observed influence of temperature on the deposit buildup rates, predicting a much stronger influence of this parameter. Model #2 was able to provide a reasonable description of the influence of temperature on the deposit buildup rates observed in the EFR experiments. A parametric study was conducted to examine the influence of some physical parameters, including ash concentration, viscosity of ash and deposits, surface tension, Young’s modulus, and porosity. On the basis of this model evaluation, where a wide range of temperatures (700–1000 °C) and fuels (straw and wood) were applied, model #2 can be regarded as a promising tool for the description of deposit formation from biomass ashes.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Model for Ash Deposit Formation in Biomass Suspension Firing. Part 1: Model Verification by Use of Entrained Flow Reactor Experiments

et al. 2016

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“…The experimental verification of Equation ( 5) was not deemed necessary at the time of compiling the current work since, first and foremost, it is a derivation of Equation (2), which was previously proposed by the authors [21]. Secondly, the above-mentioned NSI has already been validated by others [64][65][66][67]. However, the necessity of such verification is recognized and has yet to be implemented in the authors' future work.…”

Section: Quantification Of the Absolute Deposition Tendency Across The Studied Domainmentioning

confidence: 95%

“…Equation ( 5) was modified from Equation ( 2) such that the ADTs calculated by Equation ( 2) were normalized by the ash content per MJ of feedstock [kg/MJ] (calculated from the ash content and the respective lower heating value (LHV) of the raw/bio-oil/biochar). A similar numerical slagging index (NSI), which was primarily developed to determine the effect of incoming ash particles, was recently extended to and experimentally verified for coal/biomass blends by others [64][65][66][67]. The NSI bears a considerable resemblance to Equation (5) in that it too relates the slagging tendency to the reciprocal of ash viscosity and is directly proportional to the ash loading, i.e., the amount of input ash per hour [64][65][66][67].…”

Section: Quantification Of the Absolute Deposition Tendency Across The Studied Domainmentioning

confidence: 99%

“…A similar numerical slagging index (NSI), which was primarily developed to determine the effect of incoming ash particles, was recently extended to and experimentally verified for coal/biomass blends by others [64][65][66][67]. The NSI bears a considerable resemblance to Equation (5) in that it too relates the slagging tendency to the reciprocal of ash viscosity and is directly proportional to the ash loading, i.e., the amount of input ash per hour [64][65][66][67].…”

Section: Quantification Of the Absolute Deposition Tendency Across The Studied Domainmentioning

confidence: 99%

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The Feasibility of Replacing Coal with Biomass in Iron-Ore Pelletizing Plants with Respect to Melt-Induced Slagging

et al. 2020

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Combustion-generated fly ash particles in combination with the particles arising from the disintegration of iron-ore pellets, could give rise to the build-up of deposits on the refractory linings of the induration facility. Due to climate change and other environmental issues, there is a desire to cut down on use of fossil fuels. Therefore, it is of interest to investigate the feasibility of replacing coal with less carbon-intensive alternatives such as upgraded biomass, e.g., biochar and pyrolysis bio-oil. While the combustion of biomass can be carbon-neutral, the effects of biomass ash upon slagging during the iron-ore pelletizing process in a grate-kiln setup is unknown. In the present study, the effect of the interaction between the pellet dust and biomass-ash upon melt formation and the viscosity of the resulting melt, which can collectively affect melt-induced slagging, was theoretically assessed. The slagging potential of 15 different biomass fuels, suitable for the pelletizing process, was quantified and compared with one another and a reference high-rank coal using a thermodynamically derived slagging index. The replacement of coal with biomass in the pelletizing process is a cumbersome and challenging task which requires extensive and costly field measurements. Therefore, given the wide-ranging nature of the biomasses investigated in this study, a prescreening theoretical approach, such as the one employed in the present work, could narrow down the list, facilitate the choice of fuel/s, and help reduce the costs of the subsequent experimental investigations.

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“…Since not all the coals are made up with the same mineral components, it is required to have user defined function to simulate the slag growth. It is important to understand how much energy does the slag droplet has in order to predict its mechanistic bouncing potential after impact [7]. Table 1 highlighted the existing numerical slagging indices correlation which used the proximate analysis of the coal ash in order to calculate the slagging indices proposed in the earlier studies.…”

Section: Numerical Slagging Indicesmentioning

confidence: 99%

Investigation on Coal Slagging Characteristics and Combustion Behaviour in Furnace

Sophia

Hasini

2017

MATEC Web Conf.

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Abstract. This paper describes an investigation of coal characteristics and slagging potential using coal slagging assessment tool such as numerical slagging indices. Historical data on coal use according to type and shipment in power plant was use for the analysis. It is found that higher content of silica oxide results in higher softening temperature and the monomers modifiers can alter the softening temperature. Calculation also reveals encouraging conditions that could possibly prevent the slagging potential inside the furnace.

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

Cited by 33 publications

References 34 publications

Mechanistic Model for Ash Deposit Formation in Biomass Suspension Firing. Part 1: Model Verification by Use of Entrained Flow Reactor Experiments

Mechanistic Model for Ash Deposit Formation in Biomass Suspension Firing. Part 1: Model Verification by Use of Entrained Flow Reactor Experiments

The Feasibility of Replacing Coal with Biomass in Iron-Ore Pelletizing Plants with Respect to Melt-Induced Slagging

Investigation on Coal Slagging Characteristics and Combustion Behaviour in Furnace

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