Variable is

Direct Increases Increased

Direct Decreases Decreased

Reverse Increases Decreased

Reverse Decreases Increased

Getting Started Guide Tutorial 2 - Modifying the Control Scheme • 2-15

To modify properties for the newly-created controller block

MCHCOMP:

1. In the Process Flowsheet window, click MCHCOMP to select it.

2. Click with the right mouse button on the block.

3. From the menu that appears, point to Forms then Configure.

The Configure dialog box appears.

Aspen Dynamics has set default values for the controller gain

(1 %/%), integral time (20 minutes) and derivative time (0

minutes). Aspen Dynamics can also automatically initialize the

values for the operator set point, bias, the process variable

range and the controller output range. You can also manually

change any of these parameter default values.

You will now initialize the values of the controller properties:

4. On the Tuning tab of the Configure dialog box, click the

Initialize Values button.

Initializing Controller

Values

2-16 • Tutorial 2 - Modifying the Control Scheme Getting Started Guide

The value for the operator set point changes to the steady-state

value for the MCH mole composition in the distillate stream.

The value for bias changes to the steady-state value of the

phenol solvent stream flow. These values are also used to

determine default values for the process variable and output

ranges, so that the current value is at 50% of range.

5. The MCHCOMP controller should be reverse acting, so

change the controller action. Under Controller Action, select

Reverse.

In this section, to improve the performance of this controller, you

will specify values for the operator set point, the gain, and the

integral time. You will also modify the controller process variable

and output ranges on the Ranges tab.

1. On the Tuning tab, in the Operator set point box, type 0.98.

2. In the Gain box, type a gain of 6.

Дата добавления: 2015-08-20