Boiling range function

Distillation simulated by gas chromatography is a reproducible method for analyzing a petroleum cut it is appiicabie for mixtures whose end point is less than 500°C and the boiling range is greater than 50°C. The results of this test are presented in the form of a curve showing temperature as a function of the weight per cent distilled equivalent to an atmospheric TBP. 

A typical material-balance table listing the principal components or boiling ranges in the process as a function of the stream location... 

Different crude petroleums may vary greatly with regard to the abundance of the hydrocarbon components as a function of the number of carbon atoms per molecule or in boiling range—that is, some petroleums may have a preponderance of the more volatile fractions while others may have a large amount of the less volatile lubricant fractions. 

Fractionation of petroleum in the refinery, to obtain streams with specific boiling ranges for various downstream processes, is performed by distillation in a crude unit. To determine how Ni and V compounds are distributed as a function of boiling point is, therefore, useful for evaluating their impact in the refinery. Petroleum may also be fractionated by solvent separation and chromatography to obtain more detailed information on the distribution of Ni and V compounds. This section will review the available literature on how metals are distributed in petroleum by boiling point and solubility class. It will also include some discussion of the structure of heavy oil in general and asphaltenes in particular. Vercier etal. (1981) have provided an excellent review of methods and procedures involved in petroleum fractionations. 

When complex multicomponent mixtures are distilled, particularly those associated with oil refining, it is difficult to characterize them in terms of their components. Instead, they are characterized in terms of their boiling range, which gives some indication of the quantities of the components present. The true boiling point distillation (TBP) is probably the most useful, in which the percent distilled is recorded as a function of the boiling temperature of the mixture. For the TPB distillation, a 5 1 reflux ratio is often used with 15 theoretical stages in a laboratory characterization column (see Section III). 

Table V. Distribution of Nitrogen as a Function of Boiling Range...

Another important function of these two features is the reduction of convection currents directly below the evaporation layer. This insures that the composition of the liquid at the liquid-gas interface reaches a steady state such that the composition of vapor and of the liquid flowing into the boiler become identical. The time required to achieve this state will depend upon the boiling range of the charge and the conditions at the interface. 

So far these processes have been modeled in terms of lumps. In catalytic cracking the 3-lump -and the 10-lump model [Nace et al, 1971 Jacob et al, 1976] are still widely used although the lumps are based on boiling ranges rather than on chemical nature. These models contain in general only one deactivation function of an empirical nature for the reactions of the various lumps, b their study of the catalytic cracking of n-hexane on a US-Y-zeolite in an electrobalance with recycle Beimaert et al, [1994] derived an empirical deactivation function of the type (2) for the various reactions, but with different a-values, as illustrated in Table 2 for the isomerizations. 

Figure 5.3 Comparison of alumina-supported platinum-iridium and platinum catalysts showing the research octane number of the liquid reformate as a function of time on stream in the reforming of a 50-200°C boiling range Venezuelan naphtha at 487°C and 14.6 atm (33). (Reprinted with permission from Elsevier Scientific Publishing Company.)...

In Figure 5.4, the temperature required to produce 100 research clear octane number reformate is shown as a function of time on stream in the reforming of a 99-17VC boiling range naphtha containing approximately 43, 45, and 12% by volume, respectively, of cycloalkanes, alkanes, and aromatic... 

Figure 5.4 Data on the reforming of a 99-17fC boiling range naphtha showing the temperature required to produce 100 octane number product as a function of time on stream for alumina-supported platinum, platinum-rhenium, and platinum-iridium catalysts at 14.6 atm pressure (2,7).

Figure 3 shows that, at the same conversion, the selectivity of the coked catalyst for the catalytic products LPG, gasoline, LCO, and coke is equal to that of regenerated catalyst (shown as curves). The boiling ranges of the different products are given in Table 2. Details on conversion and products as function of CTO are illustrated in Figure 4 as c56. 

---