A Study of the Behavior of Phosphatic Concentrate in Gas Filtration Cake Formation

2010 ◽  
Vol 660-661 ◽  
pp. 1075-1080
Author(s):  
Amélia Giovana Fargnoli ◽  
Karina Matugi ◽  
Isabela Martinatti ◽  
Mônica Lopes Aguiar
Keyword(s):  
Filter Medium ◽  
Gas Filtration ◽  
Filtration Time ◽  
Pressure Drops ◽  
Fabric Filter ◽  
Hardening Process ◽  
Cake Formation ◽  
Cake Porosity ◽  
Modified Equation

The purpose of this study was to investigate the porosity behavior of dust cakes formed by phosphatic concentrate along filtration time. Filtration trials were performed for four different pressure drops. The fabric filter used as filter medium was a polyester felt. The dust cakes obtained were submitted to a hardening process and their images were acquired with the use of a SEM. The images generated by the SEM were analyzed by using an image analyzing program that supplied the cake porosity values. Porosity values were also estimated using Ergun’s modified equation. Results show that porosity presents higher values when calculated using the image analyzing program, but has the same behavior as the results found with Ergun’s equation. It was also observed that porosity is not constant during filtration; therefore it can be concluded that the dust cake is compressible.

In Situ Examination of Effects of Pressure Differential on Compressible Cake Filtration

1990 ◽  
Vol 22 (12) ◽  
pp. 125-134 ◽  
Author(s):  
B. R. Bierck ◽  
R. I. Dick
Keyword(s):  
Activated Sludge ◽  
Pressure Differential ◽  
Filter Medium ◽  
Cake Filtration ◽  
Solids Concentration ◽  
Cake Formation ◽  
Thin Skin ◽  
Production Behavior ◽  
Concentration Changes ◽  
Filter Cakes

A synchrotron X-ray absorbance technique was used to monitor suspended solids concentration changes in compressible filter cakes formed at different constant pressure differentials. Results for a kaolin slurry and an activated sludge manifested the markedly higher compressibility of the latter sludge. A model developed to describe effects of pressure differential on filtrate production behavior of an ideal compressible slurry indicated that the kaolin slurry behaved as such. However, the activated sludge was not ideal because changes in pressure differential did not cause the idealized change in filtrate production rate. A thin skin of activated sludge solids at the filter medium accounted for the non-ideal compressive behavior. Porewater pressure data acquired 0.86 mm above the filter medium during activated sludge filtration provided evidence of skin formation and its effect - virtually the total pressure drop occurred within this 0.86 mm region throughout cake formation (after which shrinkage began). Hence, significant effective stresses required to consolidate the sludge cake did not develop in most of the cake until cake formation was complete and shrinkage began.

Investigation into the parameters of influence on dust cake porosity in hot gas filtration

2014 ◽  
Vol 264 ◽  
pp. 592-598 ◽  
Author(s):  
M. Lupion ◽  
M. Rodriguez-Galan ◽  
B. Alonso-Fariñas ◽  
F.J. Gutierrez Ortiz
Keyword(s):  
Gas Filtration ◽  
Hot Gas ◽  
Hot Gas Filtration ◽  
Cake Porosity

Cake Fouling Mechanism and Analysis of Synthetic Coke Wastewater Treatment by Membrane Bioreactor

2011 ◽  
Vol 233-235 ◽  
pp. 953-958
Author(s):  
Gui E Chen ◽  
Ying Zhou ◽  
Zhen Liang Xu ◽  
Qiong Lu
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Formation Mechanism ◽  
Membrane Bioreactor ◽  
Fouling Mechanism ◽  
Coke Wastewater ◽  
Cake Formation ◽  
Porosity Ratio ◽  
Cake Porosity ◽  
Fouling Characteristics

Cake fouling mechanism was studied for membrane bioreactor (MBR) treatment of synthetic coke wastewater. Cake fouling characteristics of the aerobic activated sludge from MBR was investigated. The experimental results demonstrated that the cake governing equation fit the entire cake microfiltration (MF) process while cake fouling model was applicable to simulate the decrease in permeability and was used to predict the cake fouling development for both PVDF and PP MF membranes. Based on four-step development progresses, cake formation mechanism had been depicted with the increasing of TMP and the reduction of the cake porosity ratio. In addition, the comparison experiments under different operation modes were performed to further analyze the cake governing mechanism for MBR filtration.

Influence of Filtration Velocity on Cake Formation in Fibrous Filters

2012 ◽  
Vol 727-728 ◽  
pp. 1884-1889 ◽  
Author(s):  
Deivid Marques Nunes ◽  
Felipe Ferreira Gonçalves Alvarez ◽  
Fábio de Oliveira Arouca ◽  
Sandra Mara Santana Rocha ◽  
João Jorge Ribeiro Damasceno
Keyword(s):  
Low Cost ◽  
Operating Conditions ◽  
Maximum Pressure ◽  
Cake Filtration ◽  
Pressure Drops ◽  
Operating Variables ◽  
Fibrous Filters ◽  
Cake Formation ◽  
Low Sensitivity ◽  
Filter Cakes

The filtration operation is one of the most widely used procedures in gas-solid separation due to its high removal efficiency, low cost and low sensitivity to variations in operating conditions. Therefore, the objective of this work is to study the effects of operating variables (pressure drop, filtration velocities and cleaning velocity) on the formation of filter cakes using gas-solid polypropylene filter media and particulate matter as for instance phosphate rock. The filtration velocities evaluated were 5, 7.5 and 10 cm/s with maximum pressure drops of 100, 200, 300 and 400mm H2O and filter cleaning velocities of 15 cm/s by the reverse air flow method. The cake filtration porosity was estimated using the classical Ergun equation (1952) in the literature. The results led to important correlations for the use of fibrous filters in the removal of particles suspended in in micrometer aerosols.

scholarly journals A Coupled CFD-DEM Model for Resolved Simulation of Filter Cake Formation during Solid-Liquid Separation

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 826
Author(s):  
Vanessa Puderbach ◽  
Kilian Schmidt ◽  
Sergiy Antonyuk
Keyword(s):  
Filter Cake ◽  
Filter Medium ◽  
Particle Interactions ◽  
Cake Filtration ◽  
Liquid Separation ◽  
Flow Equations ◽  
Cake Formation ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Dem Model

In cake filtration processes, where particles in a suspension are separated by forming a filter cake on the filter medium, the resistances of filter cake and filter medium cause a specific pressure drop which consequently defines the process energy effort. The micromechanics of the filter cake formation (interactions between particles, fluid, other particles and filter medium) must be considered to describe pore clogging, filter cake growth and consolidation correctly. A precise 3D modeling approach to describe these effects is the resolved coupling of the Computational Fluid Dynamics with the Discrete Element Method (CFD-DEM). This work focuses on the development and validation of a CFD-DEM model, which is capable to predict the filter cake formation during solid-liquid separation accurately. The model uses the Lattice-Boltzmann Method (LBM) to directly solve the flow equations in the CFD part of the coupling and the DEM for the calculation of particle interactions. The developed model enables the 4-way coupling to consider particle-fluid and particle-particle interactions. The results of this work are presented in two steps. First, the developed model is validated with an empirical model of the single particle settling velocity in the transition regime of the fluid-particle flow. The model is also enhanced with additional particles to determine the particle-particle influence. Second, the separation of silica glass particles from water in a pressurized housing at constant pressure is experimentally investigated. The measured filter cake, filter medium and interference resistances are in a good agreement with the results of the 3D simulations, demonstrating the applicability of the resolved CFD-DEM coupling for analyzing and optimizing cake filtration processes.

scholarly journals Verification of a Combined Fouling Model to Predict Flux Decline during Ultrafiltration of Organic Solutes

2018 ◽  
Vol 22 (2) ◽  
Author(s):  
I. N. H. M. Amin ◽  
A. W. Mohammad
Keyword(s):  
Early Stage ◽  
Membrane Surface ◽  
Organic Solutes ◽  
Filtration Time ◽  
Pvdf Membrane ◽  
Flux Decline ◽  
Cake Formation ◽  
Pore Blockage ◽  
Pes Membrane ◽  
Two Stages

Studies were conducted to investigate the blocking mechanism and flux decline behavior while treating organic solutes contained in glycerin-water solutions (triglycerides, TG and fatty acid, FA). Two ultrafiltration membranes were tested, polyethersulphone (PES 25 kDa) and polyvinylidenfluoride (PVDF 30 kDa) membranes. Influence of TG and its combination (TG-FA mixtures) as foulant models, pH of feed solutions (3–10) and membrane surface chemistry were investigated. Combined blocking model was applied and the fitting were discriminate that the flux decline of PES membrane was dominated by pore blockage at the early stage and later by cake resistance during the entire filtration time. However, for PVDF membrane, cake formation mechanism was acknowledged as the major contributor to the fouling mechanism for all the parameters tested. On the other hand, the model predicts there are two stages of filtration appeared to occur, involving pore blockage at the early stage followed by cake formation.

Effect of changing vascular volume on measurement of protein reflection coefficient in ischemic lungs

2001 ◽  
Vol 280 (2) ◽  
pp. H918-H924 ◽  
Author(s):  
David B. Pearse ◽  
Patrice M. Becker ◽  
Solbert Permutt
Keyword(s):  
Weight Gain ◽  
Reflection Coefficient ◽  
Fluid Flux ◽  
Filtration Time ◽  
Lung Weight ◽  
Vascular Volume ◽  
Experimental Parameters ◽  
Convective Fluid ◽  
The Relationship ◽  
Modified Equation

In ischemic organs, the protein reflection coefficient (ς) can be estimated by measuring blood hematocrit (Hct) and protein after increasing static vascular pressure (Pv). Our original equation for ς ( J Appl Physiol 73: 2616–2622, 1992) assumed a constant vascular volume during convective fluid flux ( J˙). In this study, we 1) quantified the rate of vascular volume change (dV/d t) still present in ischemic single ferret lungs after 20 min of Pv = 30 Torr and 2) developed an equation for ς that allowed a finite dV/d t. In 25 lungs, we estimated the dV/d t after 20 min at Pv = 30 Torr by subtracting J˙ from the rate of lung weight gain (W˙L). The relationship between J˙ (0.15 ± 0.02 ml/min) andW˙L (0.24 ± 0.02 g/min) was significant ( R = 0.66, P < 0.001), but the slope was <1 (0.41 ± 0.10, P < 0.05). dV/d t(0.10 ± 0.02 ml/min) was similar in magnitude to J˙ at 20 min. The modified equation for ς revealed that a finite dV/d t caused the original ς measurement to underestimate true ς. A low ς, high J˙, high baseline Hct, and long filtration time enhanced the error. The error was small, however, and could be minimized by adjusting experimental parameters.

The Influence of the Velocity of Filtration in the Formation and Removal the Dust Cake

2010 ◽  
Vol 660-661 ◽  
pp. 46-51
Author(s):  
Sandra Mara Santana Rocha ◽  
C.B. Vasconcelos ◽  
Luiz Gustavo Martins Vieira ◽  
M.L. Aguiar ◽  
João Jorge Ribeiro Damasceno
Keyword(s):  
Life Cycle ◽  
Filtration Velocity ◽  
Filter Media ◽  
Filtration Time ◽  
Fabric Filter ◽  
Filtration Area

The effective filtration area determined in a design of fabric filter depends on the filtration velocity, also known as air-to-cloth ratio that will be used. Low filtration velocities may demand big effective filtration areas. But then high filtration velocities may wear the filters out early. By searching for more efficient and economic equipments, this paper investigated the influence of the filtration velocity by formatting and removing the dust cake. Concluding that filtering at higher velocities a higher penetration of particles in the filter media occurs. Decreasing the filtration time and increasing the number which regenerates the cloth, consequently decreasing the life cycle of the filters.

scholarly journals Development of Filter Media by Electrospinning for Air Filtration of Nanoparticles from PET Bottles

Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 293
Author(s):  
Daniela P. F. Bonfim ◽  
Fabiana G. S. Cruz ◽  
Vádila G. Guerra ◽  
Mônica L. Aguiar
Keyword(s):  
Collection Efficiency ◽  
Fine Particulate Matter ◽  
Electrospinning Process ◽  
Air Filtration ◽  
Filter Media ◽  
Gas Filtration ◽  
Pressure Drops ◽  
Support Materials ◽  
Pet Bottles ◽  
Needle Diameter

Air pollution and solid pollution are considered global problems, and endanger human health mainly due to the emission of fine particulate matter released into the atmosphere and improper disposal of post-consumer plastic bottles. Therefore, it is urgent to develop filter media to effectively protect the public. The properties of plastics make them potential candidates for nanofiber mat formers due to their attractive structural and mechanical characteristics. This work aims to produce and evaluate novel PET electrospun fibers dispensed with the use of support materials to be used as filter media to remove nanoparticles from the air. The electrospinning process was carried out by changing the concentration of the polymer solution, the needle diameter, and the electrospinning processing time at two rotation speeds. The average diameters of the micro- and nanofibers of the filter media produced ranged from 3.25 μm to 0.65 μm and it was possible to conclude that, as the size of the fibers decreased, the mechanical strength increased from 3.2 to 4.5 MPa. In filtration tests, a collection efficiency of up to 99% with low-pressure drops (19.4 Pa) was obtained for nanoparticles, demonstrating high quality factor filter media, which could be applicable in gas filtration.

scholarly journals COMPARISION OF FOUR FABRICS FOR FILTERING TURBID WATER IN A TWO STAGE CROSS-FLOW FILTER

2020 ◽  
Author(s):  
Goldie Davis ◽  
Edwin Ekwue ◽  
Vincent Cooper
Keyword(s):  
Water Treatment ◽  
Cross Flow ◽  
Filter Medium ◽  
Turbid Water ◽  
Sediment Retention ◽  
Retention Capacity ◽  
Pore Sizes ◽  
Fabric Filter ◽  
Cross Flow Filtration ◽  
Good Filter

Surface water treatment plants in Trinidad are incapable of filtering highly turbid water. Water treatment operations are shut down whenever turbidity levels rise during or after rainfall. The aim of this research is to determine the physical properties of linen, burlap, crepe-backed satin and cotton fabrics and to compare their efficiencies as filter media for reducing turbidity in water. Scanning electron microscopy was used to generate images of each fabric. Fabric weave type was determined. Inter-yarn pore sizes, inter-fiber pore sizes, warp and weft spacings, warp and weft diameters and thicknesses were measured using ImageJ. Based on the properties examined, and execution of cross-flow filtration and perpendicular filtration tests, linen was the chosen fabric filter medium. Surface profilometry resulted in linen having the roughest surface of 685.5µm and the largest maximum profile height of 3632.4µm. Linen’s inter-yarn and inter-fiber pore sizes were 41.98µm and 22.37µm respectively. This fabric had warp and weft spacings of 400µm and 700µm respectively and was 400.39µm thick. Measurements also revealed warp and weft diameters of 13.26µm and 14.96µm respectively. Linen had a high tensile strength of 402N. Linen, had a hopsack plain weave and was tightly woven; it was 95.16% porous with a sediment retention capacity of 71%. Linen is a fabric material that could prove to be a very good filter medium. Also, Acono River water turbidity levels measured ranged from 2.47NTU to 23.93NTU. Soil types contained in the turbid water were gravels, sand and silt varying from 25mm to 0.075mm in size.

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