Exercise G
81
In the software, set the value of the fluid Set Point value to the desired height. A
value of 200mm is suggested. Observe that the PSV now operates and water begins
to flow into the large process vessel.
Set the PID values for the controller in the appropriate boxes in the software.
Suggested starting values are Proportional Band (P) of 10%, Integral Time Constant
(I) of 0s and Differential Time Constant (D) of 0s.
Select the
icon to begin data logging as the process vessel continues to fill with
water.
Observe the fluid level in the vessel and the action of the PSV as the level
approaches the Set Point value. The fluid level will oscillate about the Set Point
value. Continue logging until the oscillations reach stable values, then select the
icon to finish data logging.
Disturbances
Within the software it is possible to introduce disturbances in the outflow from the
vessel by operating the Normally Closed solenoid valves SOL 2 and SOL 3:
Create a new results sheet by selecting the
icon in the tool bar of the software.
Select the
icon to begin data logging.
In the software, select the switch to open valve SOL 2. Observe the variation in the
PSV setting displayed in the software, and the oscillations in fluid level in the process
vessel.
Wait until the oscillations in fluid level stabilise in magnitude and duration, then select
the
icon to finish data logging.
Create a new results sheet by selecting the
icon in the tool bar of the software.
Close valve SOL 2 and open valve SOL 3.
Select the
icon to begin data logging.
Once again note the operation of the PSV and observe the fluid level in the process
vessel.
Wait until the oscillations in fluid level stabilise in magnitude and duration, then select
the
icon to finish data logging.
Create a new results sheet by selecting the
icon in the tool bar of the software.
Select the
icon to begin data logging.
Open valve SOL 2 so that both valves SOL 2 and SOL 3 are open. Note whether it is
possible to maintain the fluid level in the vessel by controlling the PSV valve alone. If
the fluid level remains stable, wait until the oscillations in fluid level stabilise in
To Next Page
Loading...