MPC course materials

1
Model Predictive Control Dr.Ir. Ton van den
Boom Prof.Dr.Ir. Ton Backx
October 27, 2003
2
Model Predictive Control

• Fourth lecture
• Robustness
• Distillation Case

December 20, 1999
3
Model Predictive Control

• Distillation is one of the most applied
  separation processes in the processing
  industries. It is one of the processes where MPC
  can bring significant benefits
• Tight control of quality of products
• Energy saving
• Minimization of give away

• Robustness
• Distillation Case

4
Model Predictive Control
FF inlet feed flow rate XF inlet feed
composition Fst steam flow rate Fref reflux
flow rate FD distillate (top) product flow
rate XD distillate product composition FB
bottom product flow rate XB bottom product
composition LC condenser holdup LB reboiler
holdup

• Robustness
• Distillation Case

5
Model Predictive Control

• Robustness
• Distillation Case

Increase of the reflux flow
6
Model Predictive Control

• Robustness
• Distillation Case

Responses of distillate purity and bottom product
impurity to a step in the reflux flow
7
Model Predictive Control

• Robustness
• Distillation Case

Increase of the steam flow
8
Model Predictive Control

• Robustness
• Distillation Case

Responses of distillate purity and bottom product
impurity to a step in the steam flow
9
Model Predictive Control

• Robustness
• Distillation Case

Staircase signal applied to the reflux flow
10
Model Predictive Control

• Robustness
• Distillation Case

Responses of top product purity and bottom
product impurity to a staircase change of the
reflux flow
11
Model Predictive Control

• Robustness
• Distillation Case

Responses of linearized top and bottom product
impurity to a staircase change of the reflux flow
12
Model Predictive Control

• Robustness
• Distillation Case

Step responses of the reflux flow, reboiler steam
flow and feedflow (Disturbance variable) to
log(top impurity) and log (bottom impurity)
13
Model Predictive Control
Prioritised Optimisation
Fulfill operational requirements
Satisfy MV constraints Satisfy Priority 1 zones
and targets, if not possible balance between all
priority 1 requirements Satisfy priority i zones
and targets, if not possible balance between all
priority i requirements Bring CVs as close as
still possible to optimal values Bring MVs as
close as still possible to optimal values
Fulfill quality requirements
Fulfill economic performance conditions

• Robustness
• Distillation Case

14
Model Predictive Control

• Robustness
• Distillation Case

Responses of the top product purity and bottom
product impurity to the setpoint changes
15
Model Predictive Control

• Robustness
• Distillation Case

Reflux flow and reboiler steam flow manipulations
applied by the control system
16
Model Predictive Control
Directionality of process transfer

• Robustness
• Distillation Case

17
Model Predictive Control

• Robustness
• Distillation Case

Top product purity and bottom product impurity
responses to further setpoint changes
18
Model Predictive Control

• Robustness
• Distillation Case

Reflux flow and reboiler steam flow manipulations
applied by the control system
19
Model Predictive Control
Top product purity and bottom product impurity
responses related to release of the constraints

• Robustness
• Distillation Case

20
Model Predictive Control

• Robustness
• Distillation Case

Reflux flow and reboiler steam flow manipulations
applied by the control system