Prediction Using Optimized Values of Parameters

Although for some cases an acceptable trend in the hydrotreated product properties was obtained, most of the predictions using values of parameters reported in literature were completely unsatisfactory. This obviously indicated that parameter values can be optimized for each correlation in order to determine which one can predict our experimental data with suitable accuracy. 

The best correlation to calculate API gravity as a function of HDS was a polynomial, Equations 12.51 through 12.56, with correlation coefficients in the range of 0.73-0.92 for the six feedstocks. The best correlation for the prediction of sulfur content as a function of insolubles in nC-j was an exponential function (Equations 12.91,12.92,12.94, and 12.95), which correlates data of all the feedstocks tested but for feedstock D, with values in the range of 0.6-0.97 (Table 12.7). 

The worst predictions were obtained with straight-Une correlations and an exponential correlation used to predict the nitrogen content, since most of than reported values of were between 0.0018 and 0.8. Multiple nonlinear correlations showed values of in the range of 0.87-0.97. MNL correlations use pressure. 

FIGURE 12.3 API gravity predicted with Equation 12.58 ( ) using values of parameters reported in the literature, (o) using values of optimized parameters. 

Modeling of Processes and Reactors for Upgrading of Heavy Petroleum 

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