Rigorous delta-base vectors

Workshop 4.1 Cu/de for Modeling FCC Units in Aspen HYSYS Petroleum Refining 195 Table 4.19 DELTA-BASE vectors generated using rigorous modei. 

The advantage of this method is that LP now reflects the actual capabihties of the unit and not the perceived capabilities based historical data or correlations. In addition, if the rigorous simulation is updated alongside with plant retrofits, we can modify the LP model quickly to track these retrofits. The workflow we describe in Figure 4.36 is easy to integrate into existing process simulation and LP software. Aspen HYSYS Petroleum Refining includes tools to automate the workflow and export the updated DELTA-BASE vectors to Aspen PIMS (LP software) directly. This automahon allows quick updates of the LP model to accurately reflect unit performance. 

A refinery LP and linear unit model represents a set of linear correlations that predict yield given an average yield value and changes in the certain operating variables. In this section, we discuss how to apply the rigorous reforming model in the context of a hnear unit model. The key information for a linear model of a nonlinear process is the DELTA-BASE vector ... 

Figure 5.37 Process to generate DELTA-BASE vectors from rigorous model.

We use the yield information from the rigorous model in Table 5.21 to construct the LP yield vectors. The BASE vector is the average of the yields in each RON case. We choose the average value of N-i-2A of 64 to compute the Ax . We then use one of the N-I-2A data points to compute the DELTA-BASE vector. We show the steps and results of this calculation for RON 102 case in Table 5.22. We compare the results of the linear yield vector predictions and model predictions for an intermediate N-I-2A value of 66.6 in Table 5.23. Table 5.24 shows the DELTA-BASE calculated for all the RON cases. 

---