The Use of Gravity Fractionation Techniques for Assessing Slagging and Fouling Potential of Coal Ash

Borio, R.W.; Narciso, R. R.

doi:10.1115/1.3446608

Cited by 10 publications

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“…Exam ples of the distributive nature of ash-forming species [7] in coal products and effects of the distributive nature of fuel ash on behavior under fluid bed combustion [8] and gasification condi tions [9] are presented elsewhere. The second means by which fuel ash will impact plant perform ance is the impact of slag properties in entrained-flow gasification.…”

Section: Introductionmentioning

confidence: 99%

Infiltration Velocity and Thickness of Flowing Slag Film on Porous Refractory of Slagging Gasifiers

Krishnaswamy

Kaneko

Mazumdar

et al. 2014

Journal of Energy Resources Technology

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Two analytical formulations that describe the fluid interactions of slag with the porous refractory linings of gasification reactors have been derived. The first formulation consid ers the infiltration velocity of molten slag into the porous microstructure of the refractory material that possesses an inherent temperature gradient in the direction of infiltration. Capillary pressures are assumed to be the primary driving force for the infiltration. Con sidering that the geometry of the pores provides a substantially shorter length scale in the radial direction as compared with the penetration direction, a lubrication approxima tion was employed to simplify the equation of motion.The assumption o f a fully developed flow in the pores is justified based on the extremely small Reynolds numbers of the infil tration slag flow. The second formulation describes the thickness of the slag film that flows down the perimeter o f the refractory lining. The thickness of the film was approxi mated by equating the volumetric slag production rate of the gasification reactor to the integration of the velocity profile with respect to the lateral flow cross-sectional area of the film. These two models demonstrate that both the infiltration velocity into the refrac tory and the thickness of the film that forms at the refractory suiface were sensitive to the viscosity of the fluid slag. The slag thickness model has been applied to predict film thick nesses in a generic slagging gasifier with assumed axial temperature distributions, using slag viscosity from the literature, both for the case of a constant slag volumetric flow rate down the gasifier wall, and for the case of a constant flyash flux distributed uniformly over the entire gasifier wall. IntroductionConsumption of coal in non-OECD countries (e.g., China, India, Brazil) is projected to increase at a pace of 2.1% per year until 2035 [1], While the greater reliability and availability of coal can sustain the rising energy needs of these countries; technolo gies, such as integrated gasification combined cycle (IGCC) power stations, can improve both plant efficiency and environ mental performance. Furthermore, IGCC systems can deliver enhanced environmental opportunities by providing adaptability to implementation of carbon capture and storage to achieve near zero emissions [2], Entrained-flow gasifiers convert carbon feedstock, such as coal, biomass, and/or petroleum refining byproducts into syngas, a fuel rich in carbon monoxide and hydrogen gasses. These feedstocks will typically contain inorganic ash-forming materials that are ultimately removed as slag or flyash from the system.Ash-forming constituents in gasifier feedstocks (fuel ash) will affect gasification plant performance in two ways. First, the effect of fuel ash on the conversion of the organic species in the feed stock materials to gaseous species (gasification performance) will be briefly mentioned here. Second, in the case of the entrainedflow gasification system, relates to the properties of slag generated in the...

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Section: Introductionmentioning

confidence: 99%