Proper maximal object

Also, the optimization and planning of crude allocations in Mobil s worldwide refinery system is the principal objective of Mobil s supply and distribution planning group. Overall corporate profits can be maximized by proper crude allocations to the various refineries. Similar to the refinery LPs, the reformer representation in the crude supply and distribution LP was improved. Table XX gives an example of how sensitive reformer operation can depend on the type of naphtha reformed. A significant improvement in performance and octane potential results from processing a naphthenic stock compared to a paraffinic stock. This improved performance must be balanced against differences in crude cost. 

Because it is difficult to make any reasonable estimates of the costs of aU the different contributions to the production cost, we can consider in a general discussion only some simple scenarios and their possible combinations. Since the feed cost depends essentially on the value of the recovery yield, it can be minimized by either considering optimization procedures with a constraint of min-imrun recovery yield or maximizing the product of the production rate and the recovery yield. Another possibility is to minimize the operating costs, or the fixed costs. Most practical cases are intermediate between these two extremes and can be taken care of by a proper mixing of the two objective functions (see Section 18.4.4). 

The plant economics almost always end up as costs on controller CVs or MVs or both. They tell the controller which variables to minimize and which ones to maximize to achieve the proper objective (e.g., increased profit, reduced cost, reduced environmental cost, and so forth). 

Maximizing the objective function Z under these constrants with proper limits of the operating parameters will change the related parameters to the values under which economical value Z will be maximal. In this case, the operating parameters achieve optimal values, which can be used either as set points for the closed-loop or open-loop control. 

On the other hand, the integrated approach that accounts for the maximization of a suitable financial objective function (i.e., corporate value) is able to properly assess the trade off between the increment in profit that can be achieved by fulfilling Demand at market M2 and the increment in net working capital that is required to carry out this decision. Hence, the integrated approach computes a configuration that does not fulfill the Demand in Ml due to the poor payment conditions associated with its customers. Consequently, the net working capital needed is reduced... 

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