True boiling point curves

Figure 3. True Boiling Point Curves of Polymers...

Table IV shows the properties of a typical C3 motor polymer of fullboiling range. It is somewhat heavier than the C3-C4 polymer and the octane rating is possibly a one-half number lower on the C3 polymer. The required equipment is the same as shown in Fig. 1. When C3 motor polymer is made, however, the debutanizer and rerun columns are not required. Figure 6 shows a true-boiling-point curve of typical C3 motor polymer.

FIGURE 1.19 True boiling point curve of a mixture with a limited number of components. 

A full assay involving the preparation of a true boiling point curve and the analysis of fractions and product blends throughout the full range of the crude oil. 

A complex system may be compared with a defined multicomponent system on the basis of a true boiling point curve (TBP) diagram as shown in Figure 12.18. The TBP curve is a close... 

FIGURE 12.18 True boiling point curve diagram for a complex system and a defined multicomponent system. 

The physical properties (normal boiling points, densities, and molecular weights) of the 34 pseudo components selected to represent the true boiling-point curves of the feed, distillate, and sidestreams are presented by Cecchetti et al.8 On the basis of these data, a feed composed of 34 pseudo components and having the molar compositions and total flow rate shown in Table 4-13 was selected by Cecchetti et al. The specifications for the theoretical analogue column are also given in this table. 

For more rigorous work with boiling range materials, the pseudocomponent method should be used. The true boiling point curve for the mixture (feed or product) is broken up into a series of steps as shown in Fig. 5.5-8, each step representing a pseudocomponent with boiling point as indicated. Next, the material... 

This method normally is performed by ASTM D5307. This gas chromatography method is a quick and robust method for determining a true boiling point curve and predicting cmde yields. This external standard method is done on 5 metre fused silica columns having thin film thickness allowing... 

Assay analyses of whole crudes are done by combining an atmospheric and vacuum distillation run. These two runs when combined will provide a TBP (True Boiling Point Curve). While these batch distillation methods are labor intensive, taking between three to five days, they allow the collection of distillation fractions that can be utilized for testing. While each of the distillations techniques have been standardized by ASTM, cut schemes tend to mimic Refinery product classifications and there is no standardization of the individual inspection formats. Each corporation tends to perform both physical and chemical testing that best meet the needs of their refining operations and product suites. 

This technique is performed on a 15 theoretical plate fractionation column to obtain a true boiling point curve while maintaining an approximate 5 1 reflux ratio. The still pressure is reduced in order to prevent decomposition... 

The physical distillation data from the D 2892 and D 5236 distillation runs are used to create a True Boiling Point Curve (TBP). These two curves will have a disparity in the area corresponding to the overlap between the 15/5 and Hivac distillation runs. This artifact is due to the Hivac still not being at optimum conditions at the early stages of the run. Once a TBP curve has been created property measurements can then be curve fit. 

The design methods considered for multicomponent mixtures in Chap. 9 were based on a limited number of definitely known components. In some cases, the mixtures are so complex that the composition with reference to the pure component is not known. This is particularly true of the petroleum naphthas and oils which are mixtures of many series of hydrocarbons, many of the substances present having boiling points so close together that it is practically impossible to separate them into the pure components by fractional distillation or any other means. Even if it were possible to determine the composition of the mixture exactly, there are so many components present that the methods of Chap. 9 would be too laborious. It has become customary to characterize such mixtures by methods other than the amount of the individual components they contain, such as simple distillation or true-boiling-point curves, density, aromaticity (or some other factor related to types of compounds), refractive index, etc. 

The true-boiling-point curve is an attempt to separate the complex mixture into its individual components. Actually it is a batch dis-... 

It has been found possible to use true-boiling-point curves to dehne the compositions for distillation calculation. A fraction distilling over a narrow range is taken as an individual component. Thus the fraction coming over as distillate between 39 and 40 per cent in curve B of Fig. 11-2 might be considered as a component, the boiling point of which, at the pressure at which the distillation was carried out, being... 

If the distillate during a true-boiling-point distillation were to be divided into two fractions at some convenient point. A, corresponding to the temperature h, and rimple distillation and true-boiling-point curves obtained for the two fractions, the results would resemble the... 

The true-boiling-point curves for the feed, the distillate, and the residue are given in Fig. 11-5. The curves for the liquids sampled from the plates are given in Fig. 11-6. 

Fig. 11-6. True-boiling-point curves of liquids on plates.

Fig. 19-9. True-boiling-point curves of distilled charge stocks except curve 6, which contains some residual material. (See Table 19-15 for kinds of materials.)...

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