Theoretical plate behaviour

Assuming theoretical plate behaviour, i.e., equilibrium between the gas and liquid phases, for plate n... 

Assuming the equilibrium to be expressed in terms of relative volatilities a, and theoretical plate behaviour, the relation between the vapour and liquid mole fraction compositions leaving the plate is given by... 

Assuming theoretical plate behaviour for both the column plates and the still, the corresponding vapour compositions are given by... 

Assuming theoretical plate behaviour in the column, the equilibrium is calculated by... 

As in Example BSTILL, a column containing four theoretical plates and reboiler is assumed, together with constant volume conditions in the reflux drum. The liquid behaviour is, however, non-ideal for this water-methanol system. The objective of this example is to show the need for iterative calculations required for bubble point calculations in non-ideal distillation systems, and how this can be achieved with the use of simulation languages. 

Novel general expressions were developed for the description of the behaviour of the height equivalent of a theoretical plate in various chromatographic columns such as unpacked (open capillary), packed with spherical nonporous particles and packed with spherical porous adsorbent particles. Particles may have unimodal or bimodal pore size distribution. The expression describing the mass balance in open capillaries is... 

A gas chromatographic study (Carrott and Sing, 1990) of the adsorption of a series of hydrocarbons (C2-C6) by the AMOCO AX21 carbon has revealed some unusual features. Thus, values of the height equivalent to a theoretical plate (HETP) over the range 90-l20°C were found to be independent of both the adsorptive and the temperature. Furthermore, over the range of gas flow rate studied, only the initial section of the Van Deemter plot could be observed (in contrast to the behaviour of other microporous carbons). At present, the explanation for this behaviour is not entirely... 

Separation efficiency in terms of the number of theoretical plates per meter of column length varies inversely with column radius better separation is achieved on smaller diameter columns. Columns whose inner diameters are less than 100 um, however, are extremely difficult to Interface with normal inlets and detectors. In addition, their capacities are very limited, they are easily overloaded, and their behaviour with inlet splitters (which at the present time is the most practical means of introducing a sample on these very small bore columns) can be capricious. Even the 100 tun ID column suffers from these limitations skilled chromatographers have used them to good advantage, but at our present state-of-the-art, many will experience considerable frustration with these columns. 

The number of theoretical plates N, included in Equation (8), is a measure of column efficiency, which can be individually applied to the two columns of a GCxGC set. But in comprehensive GCxGC, the use of two columns having phases with different characteristics results in the redefinition of peak capacity, a 1 D GC efficiency concept. It also results in the introduction of two new concepts related to the separation behaviour, orthogonality and chromatographic structure, which are specific to GCxGC. These three concepts are discussed in Sections 4.2, 4.3, and 4.4, respectively. 

Theories of interparticle forces play a fundamental part in many theoretical aspects of colloidal behaviour. It is therefore of great importance to have experimental evidence for the validity of these theories. One approach to this is to study the forces between macroscopic objects, to which the same theoretical equations should apply. Since these forces arc exceedingly small until the bodies come into very close proximity, work in this area has faced considerable experimental difficulties. Experiments on the force between two plates and between a plate and a lens have been of limited validity because of the difficulty in achieving adequate surface smoothness and in completely eliminating dust. The... 

When the load is applied, the pressure induced on the layer s surface results in a corresponding deflection, which is measured by two, three or even four gages. The average value of deflection measured at different magnitudes of pressure determines the pressure (kPa) versus deflection (mm) curve. Theoretically, the curve should be linear. However, this is not the case because of the nonelastic behaviour of the soil or unbound material. As a result, the k value is determined from a point of the curve as defined by the test procedure adopted. In most cases, either the pressure corresponding to 1.25 mm deflection or the deflection caused by 68.94 kPa pressure, using a 762 mm diameter plate, is used. 

Roberts T and Haji-Kazemi H (1989), Theoretical study of the behaviour of reinforced concrete beams strengthened by externally bonded steel plates , ICE Proc Part 2, 87(1). 

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