Bulk property measurements

In general we can expect to find anisotropy in all macroscopic properties Q of the nematic phase. This macroscopic anisotropy, denoted Ajg = Q - Qx (the difference between the value of the bulk property measured parallel to n, Q, and that normal to n, Qx), is simply related to the order parameter S by... 

It is now possible to carry out bulk-property measurements, at varying levels of precision and sophistication, on the elements through Cf some preliminary measurements are being made on Es. Therefore, emphasis will be placed here on methods and techniques applicable to samples in the milligram to gram range. No attention will be given to the production of actinide metals on an industrial scale. 

The feed to the fractionation system is often poorly defined in terms of actual components. We may only have an assay and associated bulk property measurements (such as density). We use the techniques discussed in Sections 1.1-1.3 to produce a complete TBP distillation curve and a density or specific gravity... 

Brdk properties refer to properties measured while taking the whole crude into account. These properties are typically density, viscosity, refractive index, etc. and are useful but do not sufficiently define the crude or a cut from this crude. DistiUation-based properties refer to the bulk properties measured for small amounts of crude based on that small amount s boiling point Typically, we present these properties as a function of these small amounts as density distributions, boiling points distributions (TBP, D-86, D-2887), etc. When a refiner considers particular crude for use, the collection of bulk and distillation based properties form particular crude s assay. This assay indicates how much of a given cut (or product) we can produce from a given crude. Tables 2.5 to 2.8 show crude assays for Arab Heavy and Arab Light crude. 

First, the model must be able to take bulk property measurements and convert them into appropriate lumps for kinetic network. This step may be quite simple if the kinetic model chosen only includes the total PNA content for the total fraction. 

Figure 5.54 shows the Feed Data tab from the Reformer sub-model. The Feed Type is a basic set of relationships and initial values for the all kinetic lumps in the reactor model. Aspen HYSYS uses bulk property information such as density, distillation curves and total PNA content in conjunction with the feed type to predict the composition of feed lumps to the model. The Default type is sufficient for hght-to-heavy naphtha. However, there is no guarantee that a particular feed type represents the actual feed accurately. Aspen HYSYS will attempt to manipulate the feed composition to satisfy bulk property measures given. In general, we advise users to develop a few sets of compositional analysis to verify the kinetics lumps calculated by Aspen HYSYS. We discuss a process to verify these lumps later. 

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