STEADY-STATE CALCULATIONS FOR CONTROL STRUCTURE SELECTION

STEADY-STATE CALCULATIONS FOR CONTROL STRUCTURE SELECTION 

Before we get into the details of converting a steady-state simulation into a dynamic one, it might make sense to discuss some important steady-state calculations that are frequently performed to aid in the selection of a practical effective control structure for a distillation column. 

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In this chapter, we have illustrated how steady-state calculations can be used to provide guidance in the selection of effective control structures for distillation columns. 

As discussed in Chapter 10, the key issue in this control structure is the selection of the control trays. Steady-state gains between tray temperatures and the two fresh feed inputs Foa and Fob are calculated numerically by making very small changes (0.5%) in one of these input variables and converging to a new steady state. The procedure is repeated for the second input variable. Figure 11.5 give these gains for aU trays. 

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