Distillation Curves of Liquid Products

100 Light Naphtha (ASTM D86) 200 180 Heavy Naphtha (ASTM D86) 

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

The integrated HCR process models are able to predict accurately the product yields, distillation curves of liquid products, and temperature profiles of reactors and fractionators. 

With the aid of the columns and other apparatus described it is possible to separate liquid mixtures continuously at normal and reduced pressures as well as at small overpressures (chap. 5.4.5) as sharply a.s in batch distillation. This is clear from the distillation curves of the products obtained in the continuous distillation of a mixture of crude fatty acids in the C4 to Ci range (Fig. 168). A further example shows that by the use of control devices it was possible to separate a mixture of phenols into its main components with great constancy. Fig. 169 illustrates the results of the first separation in this sequence, which was made between the ortho- and Twcfa/pom-cresol fractions. 

Mondragon, F., Ouchi, K. New method for obtaining the distillation curves of petroleum products and coal derived liquids using a small amount of sample. Fuel 63 (1984) p. 61-65. 

Fio. 15-14. Typical tnie-boiling-point distillation curves of vapor and liquid products from three equilibrium flash vaporizations of a petroleum fraction. (JPel. Refiner.)... 

Figure 4.83 shows the entry window for the Heavy Liquid section of the Prod Meas. Tab. The measures required for the Naphtha and LCO cuts are routine measurement data. The distillation curve, density, concarbon, sulfur content and nitrogen content are required for all the heavy liquid cuts. In addition, the Olefins, Naphthenes and Aromatics content are required for at least one of the cuts. We must also enter Cloud Point for all LCO type cuts. In most cases, we cannot obtain the distillation curve of the bottoms cut (Routinely not measured or only partial measurement available). Kaes [51] provides a simple correlation to estimate the TBP curve of a bottoms cut as a function of density only. In general, we do not require accurate values for the TBP curve of the bottoms since it is typically not a significant product... 

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. 

We only use routine measurement of feed stock (ASTM D-86, specific gravity, total sulfur and nitrogen content) to build preliminary model. Furthermore, we also use routine measurement of products (compositional analysis of gas products and distillation curve and specific gravity of liquid product) to calibrate the model. Although the resulting model provides good predictions for two months of process and production data, there are several aspects worthy being noticed. 

Step 7 Input distillation curves, elemental analyses, specific gravities and flow rates of liquid products. Distillation curves and flow rates are the most important properties and they have to be accurate to ensure that the model works well. Specific gravity affects model s prediction on hydrogenation reaction rate. Elemental analysis only affects the severity of HDN and HDS reactions and hydrogen balance which have lithe effect on yield prediction of HCR model. 

This constraint follows from the definition of a distillation curve. Each point along a distillation curve represents both the vapor and the liquid compositions just above (or below) any tray, including those at the ends of the column where products would normally be withdrawn. This constraint, together with the material balance constraint, completely defines the reachable products for a column at total reflux. 

Many processes scale directly with the feed rate to the process, e.g., distillation columns and wastewater neutralization. For distillation columns, all the liquid and vapor flow rates within the column are directly proportional to the column feed rate if the product purities are maintained and the tray efficiency is constant. For wastewater neutralization, the amount of reagent necessary to maintain a neutral pFl for the effluent varies directly with the flow rate of the wastewater feed, as long as the titration curve of the wastewater remains constant. When the manipulated variable of a process is, in general, directly proportional to the feed rate, ratio control can significantly reduce the effect of feed rate disturbances on the process. 

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