Do you know how to make your flowsheet be “smart” and adjust unit operation to changes automatically?
You can use the “User Logic” in Time Series to control the flowsheet.
The following demonstration shows how to switch on/off an extra pump when flow rate of feed stream changes. The same principle applies to other unit operations (reactor module, distillation column, heat exchanger, etc.) as well.
1. Right click on standby pump object, select Send To > Scenario in the menu.
2. Name the Scenario as Pump Switch. Change the activation method to User Logic. Update Objective is Active for ResetState as Inactive and State 1 as Active.
3. Click the State Logic button and select State 1 in the drop-down list. The Triggers for User Logic is activated as shown below.
4. Double-click the cell showing Incomplete – click here to edit.
5. In the pop-up window, you can click the button to select variables and then define the Variables as follows. Close this window once this step is completed.
6. Click the Apply State button and select ResetState. You will notice in the flowsheet that the standby pump becomes grey, indicating shutdown status.
7. Click Modify and select Append State. Define user logic so that the standby pump is inactive when flow rate is less than 145t/h.
8. Define Split ratio of tee as 0.5 for active status and 1 for inactive status.
9. You can define the feed flow rate change scenario over time. Details of this procedure are available in our earlier email for Tip 3.
10. In Time Series, define the timeline for the feed change period and strip charts for monitoring feed and pump status. Run Time Series and you will be able to observe the standby pump switched on and off automatically during the period.