Filter cake washing performance

Kuo, Ming-Ter

doi:10.1002/aic.690060412

Cited by 32 publications

(9 citation statements)

References 5 publications

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“…Ideally pulp should be washed using less amount of wash water and with maximum removal of black liquor solids. The mathematical models describing the pulp washing process are fairly well established in terms of transport equations by some earlier researchers as Lapidus and Amundson (1952), Kuo (1960), Brenner (1962), Pellett (1966), Grabs (1975), Perron & Lebeau (1977) and Sherman (1964). These transport equations together with the corresponding equations of isotherms and various boundary conditions provide the mathematical model of pulp washing, which are extremely intricate in nature and solution of these models is highly complex.…”

Section: Introductionmentioning

confidence: 98%

Analysis of Parametric Effects on Efficiency of the Brown Stock Washer in Paper Industry Using MATLAB

Kumar¹,

Kumar²,

Singh³

2009

AIP Conference Proceedings

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In the present paper, the effects of cake thickness and time on the efficiency of brown stock washer of the paper mill are studied by using mathematical model of pulp washing for the species of sodium and lignin ions. The mechanism of the diffusion-dispersion washing of the bed of the pulp fibers is mathematically modeled by the basic material balance and adsorption isotherm is used to describe the equilibrium between the concentration of the solute in the liquor and concentration of the solute on the fibers. To study the parametric effect, numerical solutions of the axial domain of the system governed by partial differential equations (transport and isotherm equations) for different boundary conditions are obtained by the "pdepe" solver in MATLAB source code. The effects of both the parameters are shown by three dimensional graphical representation as well as concentration profiles.

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Section: Introductionmentioning

confidence: 98%

Analysis of Parametric Effects on Efficiency of the Brown Stock Washer in Paper Industry Using MATLAB

Kumar¹,

Kumar²,

Singh³

2009

AIP Conference Proceedings

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“…Some of these models, e.g. side channel, film and dispersion model were presented in Kuo, 20 Sherman, 21 Wakeman, [22][23][24][25][26] Rushton, 27 Heuser 13 and Hoffner. 14 Although the theoretical models are useful to indicate dominating mechanisms of washing by comparisons with experimental data, experiments are still required to determine material behavior under different process conditions.…”

Section: Introductionmentioning

confidence: 99%

The influence of temporal cake moisture content on a discontinuous washing process in the centrifugal field

Ruslim¹,

Nirschl²,

Stahl³

et al. 2009

AIChE Journal

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In solid/liquid separation processes, filter cake washing is an essential step in improving the quality of particulate products by elimination of impurities. During cake washing and dewatering, the cake saturation changes depending on the flow conditions and it cannot always be measured and controlled accurately. This article deals with investigations on the influence of the initial and temporal cake saturation on washing PVC and silica sand particles in the centrifugal field. It was found, that high initial saturation levels and high maximum saturations during the washing process had a positive impact in inducing a high hydrostatic pressure for advective flow and enabling a homogeneous distribution of the wash water inside the cake. This was achieved by increasing the wash water flux and/or decreasing the g‐factor. A good method to obtain low final impurity quantity is the combination of washing at a low g‐factor and dewatering at a high one. © 2009 American Institute of Chemical Engineers AIChE J, 2009

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“…Whitaker ( 2 ) has recently derived a generalization of Equation (2) appropriate to an anisotropic porous medium by taking a local average of the equation of motion. In his result, P and V are…”

mentioning

confidence: 99%

“…It was developed for application to the washing of a saturated bed having voids full of filtrate. His equation fits the experimental data well when the washing operation is under way, but it fails to describe the initial piston-like displacement of filtrate at the beginning of the wash. Kuo (2) assumed that before the start of a wash cycle most of the filtrate has been forced out of the filter cake pore spaces by the pressure difference across the filter cloth and that a channel for the flow of wash liquor is formed, with a stagnant film of filtrate remaining on its surface. The washing serves to extract the remaining solute from this film.…”

mentioning

confidence: 99%

Washing of the liquid retained by granular solids

Han

Bixler

1967

AIChE Journal

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A mathematical model termed the blind side channel model is developed to describe the washing performance of liquid retained in a bed of granular solids. The effects of operating variables and system's parameters, such as the flow rate of wash liquor, the diffusivity of the liquid system, and the thickness of the bed, are discussed. The experimental washing study was carried out with granular solids such as glass beads, sand, and crystalline solids, and application of wash liquors miscible in all cases with the residual liquid in the bed, drained by centrifuging. Results from the developed model showed very good agreement with the experimental results. The developed model would be valuable in analyzing the washing performance for process improvement and in designing washing systems.The removal of the residual liquid from the filter cakes, called washing, is one of the common unit operations in the chemical industry. The liquid is held in drained or centrifuged filter cakes mainly by surface tension forces.Mathematical analysis of mass transfer between the filtrate and wash has been tried by several authors. Rhodes (1 ) presented a performance equation of this general type and correlated it with certain data for sodium chloride washing, assuming that the wash liquor was perfectly mixed with the filtrate so that the mass transfer coefficients did not appear explicitly. His performance equation was accordingly a simple exponential decay in solute concentration with time. It was developed for application to the washing of a saturated bed having voids full of filtrate. His equation fits the experimental data well when the washing operation is under way, but it fails to describe the initial piston-like displacement of filtrate at the beginning of the wash. Kuo (2) assumed that before the start of a wash cycle most of the filtrate has been forced out of the filter cake pore spaces by the pressure difference across the filter cloth and that a channel for the flow of wash liquor is formed, with a stagnant film of filtrate remaining on its surface. The washing serves to extract the remaining solute from this film. He presented transport equations that were derived by assuming that plug flow occurs in the pores of a filtered bed, with continuous mass transfer from a film of filtrate to the wash liquor. The differential equations and their solutions represent a more elegant treatment of the washing operation than those previously available. Dobie ( 3 ) set up a s stem equation for the diffusion operation and ot a was il ing efficienc assuming that the cake B orms a bundle of capi laries, that all the pores of the cake are accessible to the wash liquor, and that no viscous fingering occurs between the wash liquor and filtrate. These earlier analyses appear to be too simplified, because the flow channel in the packed bed does not consist of a simple bundle of capillaries, even in the simple case of a bed of spheres of uniform size. particles, in what may be represented by blind side channels, and not in the straight channels a...

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Filter cake washing performance

Abstract: difference between normal dew point and normal boiling point, dimensionless, Tlb -T,/ 8,,,, = corrected temperature param-B = pressure ratio dimensionless, Td-Ta eter, &A8 P d p ' , less, T,/T', T = temperature ratio, dimension-

Cited by 32 publications

References 5 publications

Analysis of Parametric Effects on Efficiency of the Brown Stock Washer in Paper Industry Using MATLAB

Analysis of Parametric Effects on Efficiency of the Brown Stock Washer in Paper Industry Using MATLAB

The influence of temporal cake moisture content on a discontinuous washing process in the centrifugal field

Washing of the liquid retained by granular solids

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