Filtration performance

D. C. Drehnel, "Relationship between Fabric Stmeture and Filtration Performance ia Dust Filtration," NTIS Pub. PB-222237, 1973. 

A conveniendy expressed coordinate for plotting filtration performance is the drainage number, jwhere d is the mean particle diameter in... 

With the above as an introduction, we now consider the important operational case of filtration performed under constant pressure. In practice, all the parameters defined above are nearly constant under steady state conditions except V and r, which are varied by the operator. We may therefore integrate the working expression for filtration over the limits of volume from 0 to V, and for residence time over the limits of 0 to x ... 

Pressure drop, final The value to which the filtration performance is measured in order to classify the filter... 

For Clean Rooms (rooms of a very high standard) dust count per unit volume will be specified, but other specifications for room cleanliness are usually in terms of filtration performance against a standard test dust. Other important features are resistance to air flow and dustholding capacity, leading to the fan energy required and filter life. 

Important parameters to characterize the properties of a drilling mud are specific weight, viscosity, gel strength, and filtration performance. 

A continuous cross-flow filtration process has been utilized to investigate the effectiveness in the separation of nano sized (3-5 nm) iron-based catalyst particles from simulated Fischer-Tropsch (FT) catalyst/wax slurry in a pilot-scale slurry bubble column reactor (SBCR). A prototype stainless steel cross-flow filtration module (nominal pore opening of 0.1 pm) was used. A series of cross-flow filtration experiments were initiated to study the effect of mono-olefins and aliphatic alcohol on the filtration flux and membrane performance. 1-hexadecene and 1-dodecanol were doped into activated iron catalyst slurry (with Polywax 500 and 655 as simulated FT wax) to evaluate the effect of their presence on filtration performance. The 1-hexadecene concentrations were varied from 5 to 25 wt% and 1-dodecanol concentrations were varied from 6 to 17 wt% to simulate a range of FT reactor slurries reported in literature. The addition of 1-dodecanol was found to decrease the permeation rate, while the addition of 1-hexadecene was found to have an insignificant or no effect on the permeation rate. 

A blend of Polywax 500 and 655 (81.3 and 18.7 wt%, respectively) with a CO-activated ultrafine iron catalyst was used for the evaluation of catalyst/ wax slurry filtration performance of the filter module with and without an alcohol compound. All of the filtration tests were conducted with a TMP of... 

A conveniendy expressed coordinate for plotting filtration performance is the drainage number, d(G )1//2 /V, where d is the mean particle diameter in micrometers, V is the kinematic viscosity of the mother liquor in m2/s (Stokes x 10-4) at the drainage temperature, and G is (02r/g r is the largest screen radius in a conical bowl. Because the final moisture content of a cake is closely related to the finest 10—15% fraction of the solids and is almost independent of the coarser material, it is suggested that d be used at the 15% cumulative weight level of the particle size distribution instead of the usual 50% point. 

After the constants have been determined, Eq. (11.7) can be employed to predict filtration performance under a variety of constant rate conditions. For instance, the slurry may be charged with a centrifugal pump with a known characteristic curve of output pressure against flow rate. Such curves often may be represented by parabolic relations, as in Example 11.2, where the data are fitted by an equation of the form... 

Figure 16.9 Effect of aeration intensity on membrane filtration performance [36].

The enzymes used for juice clarification are almost exclusively pec-tolytic. The reasons for the clarification effect are as follows. Pectin stabilizes the suspended solids in the juice. Through addition of the enzyme, the pectin is converted to a dissolved form and broken down. This is associated with a significant decrease in viscosity. In addition, pectins that have been made soluble act as protective colloids for many of the suspended particles. As soon as the protective effect of pectin is lost, these suspended particles coagulate and are precipitated. A significant decrease in viscosity is accompanied by a significant increase in filtration performance. 

Both these factors together raise the flow resistance, and there is a consequent decline in filtration performance. The performance of the sheet filter is limited by the capacity of the sheets. 

Recently, Grossner et al. used their previous findings to develop an overall transport model to predict macroscopic performance criteria such as breakthrough times and dynamics of filtration performance [88]. The model compared favourably with experimental studies on filtration phenomena by Gupta and Feke [89] (using the multi-layer resonance model of Rusinko [90]), and also with data from Grabenstetter [91]. 

Lefebvre X, Palmeri J, Sandeaux J, Sandeaux R, David P, Maleyre B, Guizard C, Amblard P, Diaz J-F, and Lamaze B. Nanofiltration modelling A comparative study of the salt filtration performance of a charged ceramic membrane and an organic nanofilter using the computer simulation program NANOFLUX. Sep. Purif. Technol. 2003 32(1-3) 117-126. 

Kamoshita Y, Ohashi R, and Suuzuki T. Improvement of filtration performance of stirred ceramic membrane reactor and its application to rapid fermentation of lactic acid by dense cell culture of Lactoccus lactis. J. Ferment. Bioeng. 1998 85(4) 422 27. 

Most of hydrodynamic methods have focused on increasing the particle back transport from the membrane-liquid interface by increasing the shear rate and the flow instability in the boundary layer. These techniques include secondary flows, spacers and inserts, pulsed flow, high shear rate devices, vibrations, and two-phase flow. The physical methods that are currently been tested to enhance filtration performance of membranes include the application of electric fields and ultrasound. 

Jaffrin et al. [57] have made a hydrodynamic comparison between the rotating disk and the VSEP system based on the flux achieved under similar maximum shear rates for baker s yeast microfiltration with an 0.2 p,m ME and skim mUk UF at 50 kDa. They found that the flux variation with time in these two modules was nearly identical when they were operated at the same maximum shear rate, suggesting the dominant effect of shear rate on the filtration performance. 

Jin YL, Speers RA, and Paulson AT. Effect of p-glucans and process conditions on the membrane filtration performance of beer. J. Am. 

For the UF of proteins, the concentration polarization model has been found to predict the filtration performance reasonably well [56]. However, this model is inherently weak in describing the two-dimensional mass transport mechanism during crossflow filtration and does not take into account the solute-solute interactions on mass transport that occur extensively in colloids, especially during MF [21,44,158,159]. The diffusion coefficient, which is inversely proportional to the particle radius, is low and underestimates the movement of particles away from the membrane [56]. This results to the well-known flux paradox problem where the predicted permeate flux is as much as two orders of magnitude lower than the observed flux during MF of colloidal suspensions [56,58,158]. This problem has then been underlined by the experimental finding of a critical flux for colloids, which demonstrates the specificity of colloidal suspension filtration wherein just a small variation in physicochemical or hydrodynamic conditions induces important changes in the way the process has to be operated [21]. 

MFI measurements are based on the formation of a cake or gel when water containing colloids are filtered through a membrane filter. Recently the use of the MFI parameter has been studied in relation to slow sand filtration performance 5 and in relation to clogging of injection wells [6 ]. 

Figure 8. (A) Flow rate vs. time during filtration of shallow and deep water at a station in Warm Core Gulf Stream Ring 82-H. (B) Flow-rate decay constant vs. total particulate matter dry-weight concentration for all samples deeper than 100 m. The linear fit to the data is pg/L = 53k + 7.6 with a correlation coefficient of 0.914 and s(y) = 4/jLg/L. Scatter in the data is attributed to additional factors such as size distribution or chemical differences among samples. (C) Filtration performance of theMULVFS in different environments.

The MULVFS pump unit weight has been reduced by a factor of 15 relative to the LVFS while maintaining filtration performance. The light weight and low exposed surface area of the MULVFS units make it practical to deploy the system in higher sea states and winds than heretofore possible. 

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