On the erosion of metal tubes in fluidized beds

Yates, J.G.

doi:10.1016/0009-2509(87)85069-8

Cited by 22 publications

(4 citation statements)

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“…(The solid particles are modelled as a "fluidized" phase [20] often have a dominant impact on generating specific flow structures (such as transient gas bubbles in fluidized beds) -which may yield apparent correlations between time-averaged wear rates and such flow structures [9,32] …”

Section: Theory 21 Preamblementioning

confidence: 99%

“…Occasionally, for multiphase flows, additional types of body forces may be found as a result of interaction between the different phases, e.g. added mass force [30], history force [31] often have a dominant impact on generating specific flow structures (such as transient gas bubbles in fluidized beds)which may yield apparent correlations between time-averaged wear rates and such flow structures [9,32] these terms evidently have no direct relationship with the basic mechanisms of wear and attrition. Eulerian differentialscale models for wear or attrition based on work of body forces violate the 1 st law of thermodynamics.…”

Section: Theory 21 Preamblementioning

confidence: 99%

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A Residual Thermodynamic Analysis of Inert Wear and Attrition, Part 1: Theory

Gustavsson¹

2015

Int. J. Thermo

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An open-system irreversible thermodynamic analysis on inert wear and attrition is presented. The aim is to derive a theory which may be implemented in computational fluid dynamics flow solvers. In order to conduct analysis on the differential scale, it is shown that traditional macroscopic-scale concepts, earlier well-established in the literature, cannot be immediately applied. Hence, new differential concepts are introduced. It is argued that the overall analysis can be split up into sub-processes, where different types of specific sub-processes of wear and attrition may be extracted, and directly connected with the corresponding breakage or deformation of either ductile-or brittle-type target materials. Applying the residual thermodynamics framework, the new concepts of wear work and attrition work (at adiabatic conditions) can be defined, which typically only represent a small -often negligible -fraction of the total work.Keywords: Differential; residual; wear work; attrition work. Introduction 1.1 Scope of Present PaperTraditional "simple" wear models [1] work excellently for developing new wear-resistant materials and analyzing specific engineering wear problems (of fixed geometry).The traditional approach aims at analyzing apparent net wear in terms of experimental operating parameters as model input. For instance, Finnie's single-particle ductile erosion model [2] and Archard's empirical model [3] applied for ductile abrasion, are generally considered to represent well-proven models. In most situations, one may connect an empirical-or general black-box model to experiments.Since the end of 1980's, Eulerian Computational Fluid Dynamics (CFD) analysis on wear is attempted. The merits of a CFD analysis is discussed by e.g. [4][5][6][7][8][9][10][11][12][13][14].The utilization or implementation of a traditional wear model in a CFD flow solver, is not straightforward. The problem at hand is that a CFD solver models a number of variables on the grid-cell scale, providing local forces, mass-flows, and momentum-and energy balances. If applying a traditional wear model, locally in a grid cell, and reversing the analysis, it can be shown that the traditional wear model input variables (which are different than the variables simulated by a CFD flow solver), combined with knowledge on the experimental conditions at which the traditional wear model was originally developed, would translate into a different set of Eulerian local forces, massflows, and momentum-and energy balances, as the set computed by the CFD flow solver. Hence, at the same grid cell position, a double set of the same Eulerian variables exists, which hence, creates serious problems of physical inconsistency. Several cases of erratic implementations of traditional wear models in CFD solvers can be found in the literature -and is discussed below.

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Section: Theory 21 Preamblementioning

confidence: 99%

Section: Theory 21 Preamblementioning

confidence: 99%

A Residual Thermodynamic Analysis of Inert Wear and Attrition, Part 1: Theory

Gustavsson¹

2015

Int. J. Thermo

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“…The major conclusions arrived at in this study are: The hydrodynamic model is capable of predicting erosion patterns and rates in fluidized beds through the use of published material properties for hardness and computed bed dynamics. Previous fluidized bed erosion models, for example, Wood and Woodford (1980) and Yates (1987), vastly simplify the hydrodynamics by assuming solids velocities and bubble and wake sizes which are not generally known a priori in operating fluidized beds containing tubes. Such assumptions are not made in our hydro-dynamic model since they arise automatically during the computations.…”

Section: Discussionmentioning

confidence: 99%

Hydrodynamics of erosion of heat exchanger tubes in fluidized bed combustors

et al. 1989

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The hydrodynamics of fluidization for two thin "two-dimensional" fluidized beds, one containing a centrally located rectangular obstacle and the other containing three square tubes roughly approximating a portion of a fluidized bed combustor (FBC), was solved using the FLUFIX/MOD2 computer program. The monolayer energy dissipation erosion model extended to include solids viscous stress was compared with the Finnie erosion model. The material properties of the eroding surface are introduced through the hardness for both erosion models. Hydrodynamic and erosion convergence studies were performed for the first bed. Computed erosion rates from the monolayer energy dissipation erosion model compare more favorably for both beds with available erosion data than those from the Finnie erosion model.On a resolu a I'aide du programme d'ordinateur FLUFIX/MOD2 I'hydrodynamique de la fluidisation pour deux lits fluidises bidimensionnels minces, I'un contenant un obstacle rectangulaire dCposC au centre du lit et I'autre trois tubes carrts reprksentant grossikrement la section d'un combusteur B lit fluidis6 (FBC). Une extension du modele d'Crosion de dissipation de I'tnergie monocouche incluant la contrainte visqueuse des solides a Cte comparee au modkle d'brosion de Finnie. Les proprittCs des matCriaux de la surface d'erosion sont introduites par le biais de la durete dans les deux modkles d'Crosion. Des etudes d'hydrodynamique et de convergence de I'erosion ont CtC menCes pour le premier lit. Les vitesses d'Crosion calculCes par ordinateur B partir du modele d'Crosion de dissipation de I'Cnergie monocouche se comparent plus favorablement pour les deux lits avec des donnCes d'Crosion disponibles qu'avec les donnCes fournies par le modkle d'krosion Finnie.

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“…The indices of the flags go from I = 1 to I = 33 and J = 1 to J = 14 (not numbered). Thus, the cells counterclockwise around the obstacle (circled for clarity) in Table 3 are (2,3), (3,3), (4,4), (4,5), (3,6), and (2,6) and the corresponding surfaces are K = 1, 2, 4, 6, 8, and 9 (also circled for clarity in Table 3). The row of cells I = 32, J = 2 to 13 are the cells next to the solid (right) wall.…”

Section: Sample Problem For a Fluldlzed Bedmentioning

confidence: 99%

User`s manual for EROSION/MOD1: A computer program for fluids-solids erosion

Lyczkowski¹,

Bouillard²,

Folga³

et al. 1992

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This reportwas preparedas an accountof work sponsoredby an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty,express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information,apparatus,product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercialproduct,process,or serviceby trade name, trademark,manufacturer,or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Governmentor any agency thereof. This report has been reproduceddirectly from the best available copy. Available to DOE and DOE contractors from the Office of Scientific and Technical Information,P.O. Box 62, Oak Ridge, TN 37831; prices availableat (615) 576-8401.

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On the erosion of metal tubes in fluidized beds

Cited by 22 publications

References 2 publications

A Residual Thermodynamic Analysis of Inert Wear and Attrition, Part 1: Theory

A Residual Thermodynamic Analysis of Inert Wear and Attrition, Part 1: Theory

Hydrodynamics of erosion of heat exchanger tubes in fluidized bed combustors

User`s manual for EROSION/MOD1: A computer program for fluids-solids erosion

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