A new model for determining mean structure parameters of fixed beds from pressure drop measurements: application to beds packed with parallelepipedal particles

Comiti, Jacques; Renaud, Maurice

doi:10.1016/0009-2509(89)80031-4

Cited by 454 publications

(236 citation statements)

References 3 publications

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“…Nevertheless, Ergun's (1952) relations work quite well for nonlinear flows in various kind of porous media and are, to a great extent, the most analyzed and used relationships (e.g., Sidiropoulou et al 2007;Li and Ma 2011;Allen et al 2013;Bagci et al 2014). Many variations on the Ergun relations for different kind of porous media with a wide range of Ergun constants A and B are addressed in the literature (e.g., Macdonald et al 1979;Fand et al 1987;Comiti and Renaud 1989). Kovács (1981) analyzed a dataset of 300 sediment samples for Re = 10−100 and proposed a value of 144 for constant A and 2.4 for constant B.…”

Section: Empirical Relations For Estimation Of the Forchheimer Coeffimentioning

confidence: 99%

The Effect of Grain Size Distribution on Nonlinear Flow Behavior in Sandy Porous Media

et al. 2017

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The current study provides new experimental data on nonlinear flow behavior in various uniformly graded granular materials (20 samples) ranging from medium sands (d 50 > 0.39 mm) to gravel (d 50 = 6.3 mm). Generally, theoretical equations relate the Forchheimer parameters a and b to the porosity, as well as the characteristic pore length, which is assumed to be the median grain size (d 50 ) of the porous medium. However, numerical and experimental studies show that flow resistance in porous media is largely determined by the geometry of the pore structure. In this study, the effect of the grain size distribution was analyzed using subangular-subrounded sands and approximately equal compaction grades. We have used a reference dataset of 11 uniformly graded filter sands. Mixtures of filter sands were used to obtain a slightly more well-graded composite sand (increased C u values by a factor of 1.19 up to 2.32) with respect to its associated reference sand at equal median grain size (d 50 ) and porosity. For all composite sands, the observed flow resistance was higher than in the corresponding reference sand at equal d 50 , resulting in increased a coefficients by factors up to 1.68, as well as increased b coefficients by factors up to 1.44. A modified Ergun relationship with Ergun constants of 139.1 for A and 2.2 for B, as well as the use of d m − σ as characteristic pore length predicted the coefficients a and b accurately.

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Section: Empirical Relations For Estimation Of the Forchheimer Coeffimentioning

confidence: 99%

The Effect of Grain Size Distribution on Nonlinear Flow Behavior in Sandy Porous Media

et al. 2017

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“…Frações de espaços vazios encontrados em leitos montados com esferas de mesmo diâmetro, para valores máximos usando diâmetros maiores, e para valores mínimos usando diâmetros menores [6] Tabela 2. Algumas relações de tortuosidade em leitos fixos encontrados na literatura, segundo Lanfrey [7] Tendo em vista que os leitos de pelotas utilizados no processo de pelotização precisam de permeabilidade suficiente para passagem do fluído para realização do tratamento térmico, e que Ergun identificou como importante a fração de Ԑ para a previsão de delta P em leitos, e que Eisfeld e Schnitzlein analisou esta fração para leitos com esferas de mesmo diâmetro, e ainda Comiti and Renaud [8] e Boudreau [9] associaram esta fração com a tortuosidade do leito, foi percebido a necessidade e oportunidade de iniciar um estudo com objetivo de estimar a métrica %Ԑ contidas e temperatura 0-50°C, dois termo higrômetros com medição de 0 a -95% RH e -10 a 65°C, e ainda dois manômetros líquidos de escala -500 a 500 mmH2O redundante para calibrações do sistema fazem as medições necessárias. O PLC localizado no painel coleta os dados do sistema e a partir de comunicação OPC migra as informações para o notebook onde tem um supervisório e ainda são calculados e encontrados os %Ԑ existentes no leito analisado, figura 4.…”

Section: Espaços Vazios Em Leitos De Partículas Esféricasunclassified

Avaliação Dos Espaços Vazios Em Leito De Pelotas Cruas E Sua Relação Com Os Parâmetros De Controle Operacional Do Pelotamento Medido Em Pot Grate

Cavalcante¹,

Figueira²,

Nunes³

et al. 2017

Anais Dos Seminários De Redução, Minério De Ferro E Aglomeração

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ResumoA permeabilidade de um leito de partículas esféricas é uma função direta dos espaços vazios, Ԑ, formados pelo empacotamento destas partículas que compõe o leito. Na literatura são encontrados estudos que envolveram leitos com um ou até dois diâmetros de partículas esféricas, contudo na pelotização o produto do disco pelotizador é uma população de aglomerados esféricos, também chamados de pelotas, com diversos diâmetros diferentes tornando a previsibilidade da medição de Ԑ imprecisa. Este estudo tem como objetivo entender qual a faixa de percentual de espaços vazios, %Ԑ, existem nos leitos encontrados na indústria de pelotização, e ainda a relação desta métrica com alguns parâmetros de controle operacional e ainda indicar testes na linha de produção para otimizar a produção de pelotas e também controlar os custos de produção. Palavras-chave: Espaços vazios; Leitos de pelotas; Qualidade; Custos. EVALUATION OF VOID IN BED RAW PELLETS AND ITS RELATIONSHIP WITH THE PARAMETERS OF OPERATIONAL CONTROL MEASURED IN POT GRATE AbstractThe permeability of a bed of spherical particles is a direct function of the voids, Ԑ, formed by packing these particles that compose it. In the literature has been found studies involving beds with one or two diameters of the spherical particles, however, the product from pelletizing disc is a population of spherical agglomerates, also called pellets, with several different diameters becomes the predictability of the measurement of Ԑ inaccurate. This study aims to understand what of the percentage range of voids, Ԑ%, there are in the beds found in the pellet industry, and also the relationship of this metric with some common operating control parameters and also indicate tests in line production to optimize the production of pellets and also control production costs.

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“…Porosity-dependent expressions for t t o can be derived from either t(n) relationships of Comiti and Renaud [1989] on the basis of analyses of flow through a bed of packed cubes,…”

Section: Modeling Effects Of Compaction On Kmentioning

confidence: 99%

Air entry–based characteristic length for estimation of permeability of variably compacted earth materials

Assouline

Or²

2008

Water Resources Research

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[1] The permeability k of a porous medium is a geometrical pore space attribute required for quantifying fluid flows and transport processes for hydrological, civil, agriculture, and petroleum engineering applications. Permeability is often expressed as proportional to a characteristic length squared and inversely proportional to factors accounting for porosity, pore shape, and tortuosity effects. Compaction and diagenesis reduce porosity, mean pore size, and connectivity, resulting in decrease in k. Permeability prediction relies on suitable selection of a characteristic length that may vary from simple hydraulic radius approximation of Kozeny-Carman to more complex critical path analysis to identify flow-limiting pore size. For porous media undergoing significant changes in pore space (e.g., compaction due to anthropogenic activities), the proper choice of a robust characteristic length is particularly challenging. We propose using the air entry pressure, a natural characteristic length that gauges the largest drainable pore size. This choice of a characteristic length is compatible with the Aissen formula that provides robust estimates of k for complex pore shapes. Additionally, the model considers geometrical (tortuosity) factors and links relative changes in porosity to concurrent changes in k. The model was tested against experimental data for sands, sandstones with different cementing agents, and unconsolidated soils. For unconsolidated sands and soils the model provides reasonable predictions of permeability for the entire range of porosities determined in laboratory or field experiments. However, for sandstones, and especially those containing cementing agents such as clay, the model is valid up to a critical porosity where hydraulic connectivity is lost, resulting in drastic reduction in k. The geometrical factor for soils was influenced by silt-to-clay ratio, while for sands, it was correlated with mean grain diameter. The model offers improvement in predicting k and provides a means for incorporating critical pore size and connectivity information in addition to porosity.

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A new model for determining mean structure parameters of fixed beds from pressure drop measurements: application to beds packed with parallelepipedal particles

Cited by 454 publications

References 3 publications

The Effect of Grain Size Distribution on Nonlinear Flow Behavior in Sandy Porous Media

The Effect of Grain Size Distribution on Nonlinear Flow Behavior in Sandy Porous Media

Avaliação Dos Espaços Vazios Em Leito De Pelotas Cruas E Sua Relação Com Os Parâmetros De Controle Operacional Do Pelotamento Medido Em Pot Grate

Air entry–based characteristic length for estimation of permeability of variably compacted earth materials

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