Flowsheet Optimizer Control Options Window

This window offers several options for controlling the behavior of the optimizer. All features have default settings.

Number of Calculation Cycles

The default value for the number of Flowsheet Optimizer cycles is calculated by PRO/II as 18 plus the number of optimization variables. You can change the maximum number of calculation cycles to some other value.

Scaling of Optimization Variables

By default, the Flowsheet Optimizer scales the optimization variables in the convergence algorithm. You can suppress the scaling by un-checking the box on this window.

Maximum Error in Optimization Variables

By default, the optimizer converges when the scaled error falls below 1.0E-7. You may change this default by entering a different value for the maximum error.

Minimum Change in Objective Function

The default value for the minimum relative change in the objective function is 0.005. You may enter a different value.

Next Unit Calculated After Optimizer Variables are Updated

For most cases, PRO/II will determine the next unit operation to calculate after the Flowsheet Optimizer. However, you must specify the next unit to be calculated if the optimization variables or constraint variables are thermodynamic parameters. See Problem Specific Calculation Sequence for more details.

Type of Thermodynamic Method

The PRO/II Optimizer currently supports the use of both Rigorous and Local Thermodynamic Models via selection of the appropriate option in the Type of Thermodynamic Model used drop-down list box as follows:

You have the option of specifying that PRO/II will use Rigorous or local thermodynamic models during the perturbation steps by selecting one of the following options:

Rigorous

Selection of this option specifies that PRO/II will use rigorous thermodynamic calculation models. This is the default selection.

Local TP Model

Selection of this option specifies that PRO/II will generate local K-value models for T and P derivatives.

Local TPx Model

Selection of this option specifies that PRO/II will generate local K-value models for T, P, and liquid composition derivatives.

Local TPxy Model

Selection of this option specifies that PRO/II will generate local K-value models for T, P, and Liquid and Vapor composition derivatives.

Advanced Options

Pushing the Advanced Options... button will allow you to specify additional advanced options for the Optimizer. See Flowsheet Optimizer Advanced Options for more details.

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