Modelling of fouling and slagging in coal-fired utility boilers

Erickson, T.A.; Allan, S.E.; McCollor, Donald P.; Hurley, John P.; Srinivasachar, S.; Kang, Sin-Wook; Baker, Joel E.; Morgan, M.E.; Johnson, Stephen A.; Borio, R.W.

doi:10.1016/0378-3820(95)00014-x

Cited by 56 publications

(42 citation statements)

References 2 publications

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“…There are two important concepts to consider: slagging and fouling. While slagging is concerned with the deposition of ash which occurs in the radiative section of a boiler, fouling occurs in the convective-pass region [2]. Vorres et al [3] observed that in certain applications coal slags generally behave more like a polymeric fluid [4].…”

Section: Introductionmentioning

confidence: 99%

On the Heat Flux Vector and Thermal Conductivity of Slags: A Brief Review

2016

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Abstract:The viscosity and the thermal conductivity of slag are among two of the most important material properties that need to be studied. In this paper we review the existing theoretical and experimental correlations for the thermal conductivity of slag. However, since, in general, slag behaves as a non-linear fluid, it is the heat flux vector which must be studied. Both explicit and implicit approaches are discussed and suggestions about the form of the heat flux vector and the thermal conductivity and their dependence on shear rate, porosity, deformation, etc. are provided. The discussion of the constitutive modeling of the heat flux vector for slag is from a theoretical perspective.

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Section: Introductionmentioning

confidence: 99%

On the Heat Flux Vector and Thermal Conductivity of Slags: A Brief Review

2016

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“…Currently, the study of the ash deposition of boilers has mainly been on utility boilers and industrial boilers [6][7][8][9][10][11][12][13][14][15]. There is little in the literature about the slagging and fouling of HRSG.…”

Section: Introductionmentioning

confidence: 99%

Slagging and Fouling Characteristics of HRSG for Ferrosilicon Electric Furnaces

Wang

Chen

et al. 2015

Energies

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Abstract:The slagging and fouling characteristics of the heat recovery steam generator (HRSG) for ferrosilicon electric furnaces are discussed in this paper. Three ash samples were taken from the HRSG of a ferrosilicon furnace in Ningxia Province, China, which suffered from serious slagging and fouling. X-ray fluorescence (XRF), X-ray powder diffraction (XRD) and scanning electron microscope (SEM) were used to analyze the ash samples. The results show that low melting point salt Na2SO4 and composite salts Na (AlSi3O8) and 3K2SO4· CaSO4 deposit on the superheater tube walls in aerosol form and solidify to form the initial slag layer. With the continuous deposition of the low melting point compounds, more and more ash particles in the flue gas adhere to the slag surface to form a thicker slag. Low melting point composite salt NaO· Al2O3· SiO2 is absorbed on the evaporator tube walls in aerosol form. With the deposition of NaO· Al2O3· SiO2, more and more ash particles are absorbed to form the fouling. Since there is less space between pin-finned tubes, the large iron-rich slag particles are easily deposited on tube walls and fin surfaces, which is advantageous to the fouling process. There are large quantities of superfine ash particles in the flue gas that easily adhere to other particles or tube walls, which facilitates the slagging and fouling process. OPEN ACCESSEnergies 2015, 8 1102

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“…Wang and Harb [4] list eight important concepts which should be addressed in any formation of ash deposits modeling: (1) understating the process of ash formation; (2) understanding the fluid dynamics and the equations governing the particle transport; (3) the process of particle impacts and sticking to the surfaces; (4) the location of deposit growth in the combustion chamber, (5) deposit properties, (6) heat transfer mechanisms through the deposit layers, (7) the effect of deposition on temperatures and heat fluxes, etc., and (8) the structure of deposit and how this affects the flow patterns in the combustion facility. Erickson et al [5] proposed three distinct layers, which include: (1) an initial layer deposit formed by small ash particles, (2) a bulk layer formed from the partially molten ash and the non-deformable particles captured by the deposit surface, and (3) a slag layer flowing as a viscous fluid.…”

Section: Introductionmentioning

confidence: 99%

“…A common definition of "slagging" is the deposition of ash in the radiative section of a boiler (whereas "fouling" refers to the deposition of ash in the convective-pass region) [5]. Slag and ash also occur in ignite-fired power plants whose main characteristics are a high water and ash content [11].…”

Section: Introductionmentioning

confidence: 99%

Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

Massoudi

Wang

2013

Energies

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Abstract:The viscosity of slag and the thermal conductivity of ash deposits are among two of the most important constitutive parameters that need to be studied. The accurate formulation or representations of the (transport) properties of coal present a special challenge of modeling efforts in computational fluid dynamics applications. Studies have indicated that slag viscosity must be within a certain range of temperatures for tapping and the membrane wall to be accessible, for example, between 1,300 °C and 1,500 °C, the viscosity is approximately 25 Pa·s. As the operating temperature decreases, the slag cools and solid crystals begin to form. Since slag behaves as a non-linear fluid, we discuss the constitutive modeling of slag and the important parameters that must be studied. We propose a new constitutive model, where the stress tensor not only has a yield stress part, but it also has a viscous part with a shear rate dependency of the viscosity, along with temperature and concentration dependency, while allowing for the possibility of the normal stress effects. In Part I, we reviewed, identify and discuss the key coal ash properties and the operating conditions impacting slag behavior.

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Modelling of fouling and slagging in coal-fired utility boilers

Cited by 56 publications

References 2 publications

On the Heat Flux Vector and Thermal Conductivity of Slags: A Brief Review

On the Heat Flux Vector and Thermal Conductivity of Slags: A Brief Review

Slagging and Fouling Characteristics of HRSG for Ferrosilicon Electric Furnaces

Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

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