Mechanistic modeling, numerical simulation and validation of slag-layer growth in a coal-fired boiler
TL;DR: In this paper, a mechanistic bouncing potential model, incorporating the phenomenon of recoiling of molten ash droplets after impaction, is employed to determine the outcome of slag-layer impaction.
About: This article is published in Energy.The article was published on 2015-03-01. It has received 34 citations till now.
Citations
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TL;DR: In this article, a comprehensive review on the development of the modelling of ash deposition with particle combustion, sticking, rebound and removal behaviors is presented, including the modeling of ash deposit morphomology.
117 citations
TL;DR: In this article, the authors summarized the development of the simulations and experimental studies for the fouling, erosion and corrosion of heat exchangers and proposed the novel heat exchanger for anti-fouling, anti-erosion and anti-corrosion.
84 citations
TL;DR: In this article, a dynamic CFD model based on inertia impaction, thermophoresis and the direct alkali vapour condensation incorporating the influence of the heat transfer to the tube, has been developed for predicting the ash deposition formation in Zhundong lignite combustion in a pilot-scale furnace.
63 citations
TL;DR: In this article, an unsteady CFD model of the convective section of a 100kW PC pilot-scale combustor is implemented aiming to simulate and study the ash deposition trends.
33 citations
TL;DR: In this article, a CFD model of a transversally-periodic bundle of four in-line tubes of a kraft recovery boiler bank for ash deposition calculations was presented.
32 citations
References
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TL;DR: An overview of the art of ash deposition while firing coal, the mechanistic approach to the problem, the recent introduction of sophisticated analytical procedures, and modeling of mineral transformations, and ash deposition underway are presented in this paper.
769 citations
TL;DR: In this paper, a rebound model was proposed to predict the tendency of a droplet to deposit or to rebound on flat surfaces at room temperature at impact velocities, viscosities, and surface roughness.
Abstract: The spread and rebound of droplets upon impact on flat surfaces at room temperature were studied over a wide range of impact velocities (0.5–6 m/s), viscosities (1–100 mPa.s), static contact angles (30–120°), droplet sizes (1.5–3.5 mm), and surface roughnesses using a fast-shutter-speed CCD camera. The maximum spread of a droplet upon impact depended strongly on the liquid viscosity and the impact velocity. The tendency of a droplet to deposit or to rebound is determined primarily by the liquid viscosity and the liquid/substrate static contact angle. A model more broadly applicable than existing models was developed to predict maximum spread as a function of the Reynolds number, the Weber number, and the static contact angle. Based on the conservation of energy, a rebound model is proposed that predicts the tendency to rebound as a function of maximum spread and static contact angle.
The maximum-spread model prediction agrees to within 10% with more than 90% of the experimental data from different sources. In the current study, the rebound model successfully predicts the tendency of a droplet to rebound.
561 citations
TL;DR: In this paper, the authors used a steam-cooled tube at the exit of a pilot scale furnace during combustion of bituminous coal to identify coal properties and combustion conditions with which one may anticipate fouling and slagging of superheaters in electric utility boilers.
208 citations
TL;DR: In this paper, the authors defined the process of removing coal ash from the heat transfer surfaces as a process of shedding, which can be then referred to as artificial shedding, where both mechanical and thermal shock devices for shedding can be implemented within into the boiler, and the mechanism that will dominate depends on the ash characteristics and the boiler operation.
174 citations
TL;DR: In this paper, the sessile-drop method has been used to determine the Wettability of silica by gold, silicon, and lead by using an empirical equation which takes into account both metal-oxygen and metal-oxide chemical bonds.
Abstract: Wettability of silica by gold, silicon, and lead has been determined by the sessile-drop method. The contact angle, θ, and the work of adhesion, W, have been found to be 143° and 227 mJ·m−2 for gold at 1353 K, 87° and 869 mJ·m−2 for silicon at 1723 K, and 120° and 203 mJ·m−2 for lead at 1000 K. Thermodynamic adhesion between silica and nonreactive pure metals has been analyzed using models for metal-oxide bonds. Models based on the assumption that only van der Waals interactions and/or metal-oxygen chemical bonds exist at the metal-oxide interface are unsuited for explaining the relative variations in the W values. A valid model can be accomplished by using an empirical equation which takes into account both metal-oxygen and metal-oxide chemical bonds. It appears that chemical bonds exist at the interface even for nonreactive metal-ionocovalent oxide systems.
173 citations