Plate equivalent

Increase the number of plates equivalent to the system (adjusting column length, or fluid velocity). 

Example 8.7 Determine the flat-plate equivalent to Merrill and Hamrin s criterion. 

FIGURE 11.7 Sample distribution. The well number and the percent inhibition are reported on the x- and y-axes, respectively. Different symbols denote values from different microplates. The results from a total of 200 plates, equivalent to 16,000 samples, are included in the graph. Horizontal lines mark 30%, 60%, and 90% inhibition. The vast majority of samples give an inhibition oscillating +15% of the controls. In this case the threshold was set at 40% inhibition and only 8 of 16,000 (0.05%) samples performed above this value. The overall positive rate for the entire project was 0.3%. The data refer to the same HTS project as Figure 11.5. 

The plate equivalent is the minimum number of plates required at infinite reflux ratio to attain the same enrichment (xB- -Xg) as in a countercurrent distillation with a finite reflux ratio. All distillation conditions except the reflux ratio remain the same. Thus, in the McCabe-Thiele diagram the separating stages are drawn between the diagonal and the equilibrium curve v = oo). 

Relating the plate equivalent to the plate number at = oo for the same load we obtain, according to Obolonzev and Frost [202], the useful efficiency of a column ... 

The method involving plate equivalents and the useful efficiency has the distinct... 

Plate equivalent as a function of the amount of distillate taken off, from 0 — 50 vol% (chlorobenzene-ethylbenzene)... 

Theoretical stages (-------) and plate equivalents (-------) as a function of load... 

The most recent core shdl particles consist of a solid 1.3-2.6 im core with a relatively thick porous 0.2-0.5 pm shell. The homogeneous porous shell is grown on a solid silica core by sol-gel techniques. The current standard pore size is 10 nm and the surface area is about 200 m g. Due to the small particle sizes and the short diffusion paths, 5 cm columns may give up to 15 000 plates, equivalent to 300000 plates per meter. The 1.7 pm particles are available in 5, 10, and 15 cm columns, with inner diameters of 2-4.6mm. The smallest particles need ultrahigh-pressure systems (600-1000 bar). Core-shell particles allow high flow rates due to the fast mass transfer. 

Consider now thermal coupling of the prefractionator arrangement from Fig. 5.116. Figure 5.16a shows a prefi-actionator arrangement with partial condenser and reboiler on the prefractionator. Figure 5.166 shows the equivalent thermally coupled prefractionator arrangement sometimes known as a Petlyuk column. To make the two arrangements in Fig. 5.16 equivalent, the thermally coupled prefractionator requires extra plates to substitute for the prefractionator condenser and reboiler. 

In the case of a plate column the performance of a real plate is related to the performance of a theoretical one by the plate efficiency. In the case of a packed column the height equivalent to a theoretical plate HETP) gives a measure of the contacting efficiency of the packing. 

The sample is distilled at predetermined and precisely controlled temperatures under conditions that give a fractionation equivalent to about one theoretical plate. 

In the case of a charged particle, the total charge is not known, but if the diffuse double layer up to the plane of shear may be regarded as the equivalent of a parallel-plate condenser, one may write... 

A number of more or less equivalent derivations of the electrocapillary Eq. V-49 have been given, and these have been reviewed by Grahame [113]. Lippmann based his derivation on the supposition that the interface was analogous to a parallel-plate condenser, so that the reversible work dG, associated with changes in area and in charge, was given by... 

Non-covalent interactions between molecules often occur at separations where the van der Waals radii of the atoms are just touching and so it is often most useful to examine the electrostatic potential in this region. For this reason, the electrostatic potential is often calculated at the molecular surface (defined in Section 1.5) or the equivalent isodensity surface as shown in Figure 2.18 (colour plate section). Such pictorial representations... 

Sometimes the height equivalent to a theoretical plate (HETP) is employed rather than and to characterize the performance of packed towers. The number of heights equivalent to one theoretical plate required for a specified absorption job is equal to the number of theoretical plates,... 

The first differential centrifugal extractor to be used in industry was the PodbieHiiak extractor which was introduced in the 1950s (209,210) and can be regarded as a perforated-plate column wrapped around a rotor shaft. Rotation creates a centrifugal force which results in a great reduction in the equivalent height and contact time that would be needed in a conventional perforated-plate column. 

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