| Operating
Unit / Process |
What
to Control |
Why
Is It Difficult |
Which
MFA to Use |
Distillation columns
Application
Sheet |
Plate & bottom temp |
1-input-2-output process |
2x1 MFA |
| Level |
Avoid flooding or drying |
Robust MFA |
| Pressure |
Nonlinear |
Nonlinear MFA |
| Flow |
Nonlinear |
Nonlinear MFA |
Reactors
Application
Sheet |
Reactor temperature |
Nonlinear, time-varying, large dynamic changes |
Robust MFA |
| Heating/cooling loop |
Split-range gain changes |
Nonlinear MFA |
Refining furnace
Application
Sheet |
Oil outlet temperature |
Large time delays |
Anti-delay MFA |
| Zone temperature |
Multiple zones |
MIMO MFA |
| Combustion |
Optimal fuel-air-ratio |
SISO MFA |
Coking furnace
Application
Sheet |
Oil outlet temperature |
Multiple passes |
MIMO MFA |
| Combustion |
Optimal fuel-air-ratio |
SISO MFA |
Chemical production
Request
white paper |
Chemical strength or concentration |
Large time delays |
Anti-delay MFA |
Air separation unit
Application
Sheet
Article
|
HP column reflux level |
Time-varying, large disturbances |
Robust MFA |
Ammonia plant
Request
white paper |
N-H ratio outer loop |
Large time delays |
Anti-delay MFA |
| N-H ratio inner loop |
Time varying |
SISO MFA |
Chemical concentration
Application
Sheet
|
pH control |
High accuracy pH control |
MFA pH or
Anti-delay MFA pH |
Wastewater treatment
Application
Sheet
|
pH control |
Large gain changes in Log scale, large delay time |
MFA pH or
Anti-delay MFA pH |
Catalyst or powder conveyor process
|
Vacuum pressure |
Large time delays |
Anti-delay MFA |
Heat-exchangers
Request
white paper |
Temperature |
Interactions among temperature points |
MIMO MFA or FD/FF MFA |
