Pseudocomponents boiling-point ranges

A new kinetic model for hydrodesulfurization (HDS) of oil products is proposed. The model is based on a discretization of the entire sulfur GC-AED spectrum into small pseudocomponents of only 1°C boiling point range. In addition, a few components with particularly low reactivity, like 4-Me-DBT and 4,6-Me-DBT, are identified and modeled separately. Experiments on a lab reactor are used to identify the kinetic parameters for an LGO feed. A good fit was obtained, and the model is now used to predict the conversion in an industrial trickle bed reactor. 

Pseudocomponent Generation Based on Boiling-Point Ranges... 

The determination of number of cuts is arbitrary. Table 1.2 lists the typical boiling-point ranges for pseudocomponents in commercial simulators. 

Boiling-point Range Su ested Number of Pseudocomponents... 

The previous sections in this chapter address the creation of pseudocomponents by cutting an assay curve into a set of discrete components based on boiling-point ranges. We also briefly alluded to physical properties and process thermodynamics selection in the earlier workshops of this chapter. In this section, we consider, in detail, the problem of how to represent these components in the process modeling software. There are two major concerns in this area physical properties of pseudocomponents and selection of a thermodynamic system that can deal with these hydrocarbon pseudocomponents in the context of refinery modeling. 

Boiling-Point Range Boiling-Point Width of Each Pseudocomponent Number of Pseudocomponents per 100 °F... 

Delumping the reactor model effluent is an essential step to integrate the reactor model with the fractionator model, because kinetic lumps used in the reactor model are based on the structure and carbon number and cannot represent accurate thermodynamic behavior of the fractionator model. Because boiling point (volatility) is the most important property for distillation operation, process modelers typically use pseudocomponents based on the true boiling point (TBP) curve to represent the feed oil to the HCR fractionators. We present five steps to develop pseudocomponents based on boiling-point ranges to represent the petroleum fraction [32, 34] ... 

Cut the entire boiling range into a number of cut-point ranges to define the pseudocomponents based on boiling-point ranges (see Figure 6.20). 

Haynes and Matthews [38] apply the Gauss-Legendre quadrature to predict the vapor-liquid equilibrium (VLE) of thydrocarbon mixture derived from a continuous equation-of-state developed by Cotterman et al. [39]. Later, Mani et al. [40] extend the work of Haynes and Matthews [38] to partition the cut-point ranges of the TBP curve of a petroleum fraction to define pseudocomponents based on boiling-point ranges, and the predicted VLE satisfactorily matches the experimental data. Hence, we extend the method represented by Mani et al. [40] to delump the reactor model effluent into pseudocomponents. 

Figures 6.45 to 6.48 illustrate the specific gravity predictions of liquid products, which are calculated by Aspen HYSYS. The accurate predictions not only reflect the accuracy of the model to predict specific gravity of the liquid product, but also demonstrate that the delumping method described in Section 6.4.5 is able to carry over density distribution to pseudocomponents based on boiling-point ranges.

We apply the Gauss-Legendre Quadrature to convert kinetic lumps into Pseudocomponents based on boiling-point ranges (delumping) for rigorous fractionator simulation. 

Generating the pseudocomponents from a TBP curve is accomplished by breaking the curve into a number of cuts, as shown in Figure 1.21. Temperatures Tci, Tq2, Tc3> define the cut points. Thus, the first pseudocomponent boiling range is from... 

It is required to represent this crude oil by pseudocomponents with boiling points separated by approximately 50°C in the lower boiling range and 100°C in the upper boiling range. 

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... 

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