Filtrability

In principle, filter bed permeabilities can be calculated using the Carman-Kozeny equation 2.53. For slurries containing irregular particles, however, cake filtrabilities together with filter medium resistance are determined using the Leaf Test (Figure 4.13). In this technique, a sample of suspended slurry is drawn through a sample test filter leaf at a fixed pressure drop and the transient volumetric flowrate of clear filtrate collected determined. 

Finally, it should be emphasized that in all these studies more than one particle characteristic should be determined and this will usually entail more than one method of measurement. These can include various sizing techniques and the value of microscopy should not be ignored. Often, however, end-use tests provide the most meaningful data e.g. sedimentation rates or filtrability. 

It was shown in Chapter 2 that the simplest models of solid-liquid separation are those based of the Carman-Kozeny equation for filtration in whieh the bed permeability (filtrability), F, may be expressed by... 

Mathews and Rawlings (1998) successfully applied model-based control using solids hold-up and liquid density measurements to control the filtrability of a photochemical product. Togkalidou etal. (2001) report results of a factorial design approach to investigate relative effects of operating conditions on the filtration resistance of slurry produced in a semi-continuous batch crystallizer using various empirical chemometric methods. This method is proposed as an alternative approach to the development of first principle mathematical models of crystallization for application to non-ideal crystals shapes such as needles found in many pharmaceutical crystals. 

Giorgio, S. and Kern, R., 1983. Filtrability, crystal morphology and texture paraffins and de-waxing aids. Journal of Crystal Growth, 62, 360-374. 

Jones, A.G. and Mydlarz, J., 1990b. Slurry filtrability of potash alum crystals. Canadian Journal of Chemical Engineering, 68, 513-518. 

Mydlarz, I. and Jones, A.G., 1989. Crystallization and subsequent solid-liquid separation of potassium sulphate. Part II Slurry filtrability. Chemical Engineering Research and Design, 67, 294-300. 

Electrostatic precipitators (ESP) and wet gas scrubbers (WGS) are widely used to remove particulates from the FCC flue gas. Both can recover over 80% of filtrable solids. An ESP (Figure 10-6) is typically installed downstream of the flue gas heat recovery (prior to atmospheric discharge) to minimize particulate concentration. If both low particulate and low SO requirements are to be met, a wet gas scrubber such as Belco s (Figure 10-7) should be considered. If SO removal... 

Filtrability seems not to be greatly dependent on floe size. 

Traditional permeability tests are time-consuming and subject to some uncertainties (4). In the present paper, we describe an automated technique for determining the filtrability of fairly dilute suspensions, which can give useful information, on the behaviour of polymeric flocculants. 

The flocculation and restabilization behaviour indicated by the filtrability results is well matched by other test methods, including simple settling tests and a newly-developed optical monitoring technique (13). All of these methods give essentially the same optimum polymer concentration. 

For this purpose, 500 ml of a 140 mg/1 kaolin suspension was treated with an amount of polymer A corresponding to 0.5% of the clay concentration (i.e. the optimum dose). After 15 seconds of rapid mixing, the suspension was subjected to slow (30 r.p.m.) stirring, using a paddle stirrer. Samples were withdrawn at different intervals directly into the syringe and a filtrability determination was carried out. 

However, as a means of studying the filtrability of suspensions and the effect of particle aggregation, either in fundamental work or in practical applications, it could prove to be useful. 

Diet Fractional Renal Ca Reabsorption (%) Plasma Ultra-filtrable Ca (mg/100 ml) Urinary Cyclic AMP (ymoles/day) Urinary Hydroxyproline (mg/day)... 

To eliminate the threat of shock, replenishment of the circulation is essential. With moderate loss of blood, administration of a plasma volume expander may be sufficient Blood plasma consists basically of water, electrolytes, and plasma proteins. However, a plasma substitute need not contain plasma proteins. These can be suitably replaced with macromolecules ( colloids ) that like plasma proteins, (1) do not readily leave the circulation and are poorly filtrable in the renal glomerulus and (2) bind water along with its solutes due to their colloid osmotic properties. In this manner, they will maintain circulatory filling pressure for many hours. On the other hand, volume substitution is only transiently needed and therefore complete elimination of these colloids from the body is clearly desirable. 

For materials with melting points below 70 it is sometimes convenient to use dilute solutions in acetone, methanol, pentane, ethyl ether or CHCI3-CCI4. The solutions are cooled to -78 in Dry-ice, to give a filtrable slurry which is filtered off through a precooled Buchner funnel. Experimental details, as applied to the purification of nitromethane, are given by Parrett and Sun [7 Chem Educ S4 448 1977],... 

Type of Centrifuge Continuous Automatically Discharged at Full Speed Automatically Discharged at Reduced Speed g-Factor Range IFC) Minimum Solid Concentration in Feed [% by Volume (C ) Possibility of Washing Minimum Particle Size, mm Minimum Filtrability Coefficient (fr)(m/sec) Maximum Retention Time (Sec)... 

A Teflon-coated sampler (General Oceanics, 10-L Go-Flo) on a stainless steel hydrowire was used to obtain whole-water samples and samples for filtration from 16 points in the water column on each cruise. Samples were pressure filtered onboard ship, within a Class-100 laminar flow enclosure, in an all-Teflon column-filter holder (Savilex) through tared 0.4-pm track-etched filters (Nuclepore). Samples, both total P and total filtrable P, were acidified with high-purity HC1 (Ultrex) and immediately frozen. 

Whole-water (total P) and filtrable phosphorus (total filtrable P, 0.4 pin) analyses were performed by the ascorbic acid technique (18) after digestion with persulfate. 

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