1. Level control.
Figure: On-off level control loop.
a - by the control of an inlet stream; b - by the control of an outlet stream;
c - cascade control loop.
Figure: Level control in evaporator.
2. Pressure control
Figure: Pressure control loop for evaporating unit.
1, 2 - evaporating units; 3 - barometric condenser.
Figure: Pressure control in the distillation column.
1 - distillation column; 2 - reflux column; 3 - reflux tank;
3. Temperature control
Figure: Single loop control system for a stirred tank.
Figure: Single loop control system for heat exchanger.
Figure: Cascade control system for heat exchanger.
4. Flow control
Figure: Flow control by throttling the stream after the centrifugal pump.
Figure: Flow control using by-pass pipe-line in the case of the piston pump.
5. pH control
6. Composition control
Figure: Feedback system for composition control.
Figure:Inferential system for composition control.
Note: Click on the image to get an enlarged view.
Article Source:: Dr. Alexander Badalyan, University of South Australia