Simulating a Disturbance

Now that you have used Aspen Dynamics to reproduce the steady-

state results from Aspen Plus, you can simulate a disturbance by

changing the composition of the feed to the column. To do this:

1. Select the Stream 1 Manipulate Table to make it the active

window.

2. Click the value cell for MCH component flow (FcR("MCH"),

and replace 200 with 220.

3. Click the value cell for Toluene component mole flow

(FcR("TOLUENE") and replace 200 with 180.

4. Press Enter to confirm the changes.

The Stream 1 Manipulate Table looks like this:

5. Close the Stream 1 Manipulate table.

To set a new stop point, and continue the run:

1. From the Run menu, click Pause At. The Pause Time dialog

box appears.

2. In the Pause At Time box, Type 2.5, and click OK.

3. On the Run Control toolbar, click the Run button to

continue the simulation.

4. In the MCH Purity Control plot, view the progression of the

run.

The run stops at a simulation time of 2.5 hours. The controller

response restores a steady-state condition.

After the run stops, you can view the full response.

3-10 • Tutorial 3 - Running the Dynamic Simulation Getting Started Guide

When the run has finished, you can view the full response.

To do this:

1. Click an empty area on the plot and click the right mouse

button.

2. From the menu that appears, click Zoom Full.

The plot that appears is similar to this:

The plot shows how the change in feed composition affects the

distillate purity. You also see how the solvent flow is manipulated

by the controller, to maintain the purity set point of 0.98. With the

specified controller parameters, the controller returns the purity to

the set point within 2 hours.

Дата добавления: 2015-08-20