Level Control Experiment
No Control Answers
You should have noticed that opening the valve tended to reduce the
level in the
tank to a new steady state and closing the valve brought the level to a
higher
steady state. Taken to the extremes, as the valve is closed, the tank
will overfill
and as the valve is opened, the tank will empty. Clearly, both of these
possibilities
are unacceptable indicating the need for some sort of control.
Likewise, increasing the flow (for a set valve position) brings the tank
level to a
new higher steady state and decreasing the inlet flow reduces the level to a
new
steady state. It should be noted that as the flowsheet shows to overfill
line, the
tank could overfill at high flows. Decreasing the flow could, in the
extreme, drain
the tank. This is as a result of the mass balance. (ie like filling or
emptying a
bath!)
Increasing or decreasing the flow to the tank will require a larger
or smaller
valve respectively (assuming no control) and the range of control is
limited by the
size of this valve.
Return to the Pre Experimental
questions