Prediction of Distillation Curves

FIG U RE 11.14 Residual plot distillation data using the continuous kinetic model. 

Modeling of Processes and Reactors for Upgrading of Heavy Petroleum 

The developed continuous kinetic model and correlations of parameters to consider the effect of tanperature and pressure were tested for the prediction of distillation curves of hydrocracked products obtained at different LHSV from those with 

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Figure 6.38 Predictions of distillation curves of liquid products (data set 1 in MP HCR).

We apply Equations (6.25)-(6.28) to estimate the flash points and freezing points of diesel ful in MP HCR process and jet fuel in HP HCR process by models predictions on distillation curve, specific gravity, and MeABP. 

Composition, particularly C3 and C4, is the most important indicator to evaluate the quality of the LPG product Figure 6.59 represents selected model predictions on LPG composition with AAD of each component. For the most important components, C3 and C4, the model shows only 0.021 and 0.058 AADs, respectively, in molar fraction predictions. For other liquid products, the distillation curve is the most popular analysis to indicate the vaporization temperature after a certain amount of oil fraction vaporized. Figures 6.60 and 6.61 illustrate selected model predictions on distillation curves of light naphtha, heavy naphtha, jet fuel, and residue oil. 

Regarding feed characterization, there is a need to characterize the residue from commonly available information without losing its essential characteristics. Typical feed analysis consists of distillation curve, kinematic viscosity, specific gravity, and sulfur, asphaltenes, and CCR residue contents. To develop more detailed kinetic models, advanced characterization is necessary for instance, SARA (saturates, aromatics, resins, asphaltenes) composition and analysis of each component would improve the prediction capability of kinetic models. 

The experimental data of distillation curves of hydrocracked products obtained at the lowest LHSV (0.33 h ) at three reaction temperatures were used to determine the optimum set of parameters (5, a, Aq, a, and of the continuous kinetic model. Figure 11.6 shows the comparison between experimental and predicted distillation curves of the feedstock and the product hydrocracked at LHSV of 0.33 h" and 420°C. This plot is an example of the way the data are fed and reported by the MATLAB computer program as dimensionless curves. At 420°C, the optimum set of parameter values is a = 0.246, = 1.487, = 22.83, 8 = 1.67 x 10" , and... 

Fractional distillation. The aim of distillation is the separation of a volatile liquid from a non-volatile substance or, more usually, the separation of two or more liquids of different boiling point. The latter is usually termed fractional distillation. The theoretical treatment of fractional distillation requires a knowledge of the relation between the boiling points, or vapour pressures, of mixtures of the substances and their composition if these curves are known, it is possible to predict whether the separation is difficult or easy or, indeed, whether it will be possible. 

Usually, product specifications for a crude distillation unit are expressed in terms of the products 15/5 or ASTM distillation curves. The prediction of a product 15/5 distillation is accomplished simply by blending the quantities of the pseudo components in the stream so as to form a true boiling point, 15/5 equivalent, distillation curve. This curve can then be converted to an ASTM type distillation using an empirical method. Figure 5 illustrates how a typical ASTM curve compares to the 15/5 curve for the same material. 

Figures 10 and 11 show some examples of model predictions of the feedstock characterization of crude distillation residues. Figure 10 compares model predictions with the experimental distillation curves of three Arabian atmospheric residues. Figure 11 shows the model ability in predicting the aromatic carbon content and the H/C of different feeds in comparison with some NMR data. A more detailed description and discussion of this residue characterization is reported elsewhere (Bozzano et al., 1995, 1998).

Fig. 10. Predicted and experimental distillation curves of Arabian residues (Ali et al., 1985).

The form of these curves depends largely on the chemical relationship of the components, and it is now possible, in a moderate number of cases, to form an estimate, from the chemical constitution of the substances, of the extent to which the curves would deviate from the normal form, and therefore to predict the behaviour of a mixture on distillation,... 

A1.1 Results obtained by this test method may be used to calculate the vapor pressure of the gasoline sample, including its Reid vapor pressure (RVP) and to predict the Test Method D 86 distillation curve. 

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