Use MMC Function Block for Splitter Control
The following example describes using an MMC function block to control a splitter. Refer to the MMC Function Block Splitter Example Configuration in Module Multivariable Control ( MMC).
Item | Description |
PV1 | Top composition (more important) |
PV2 | Bottom composition (less important) |
Active 1st CV for PV1 | CV1 (reflux ratio) |
Active 2nd CV for PV1 | CV3 (pressure setpoint) |
Active 3rd CV for PV1 | CV2 (steam (flow) |
Active 1st CV for PV2 | CV2 |
Active 2nd CV for PV2 | CV3 |
Active 3rd CV for PV2 | CV1 |
TargetCV | CV3 (pressure should be held constant if possible) |
CV3Target | 60% (of pressure range) |
The MMC calculates CV1, CV2, and CV3 so that the control goals are accomplished in the following order of importance:
- Control PV1 to SP1 (PV1 is always considered more important than PV2)
- Control PV2 to SP2
- Control CV3 to its target value
CV1 is selected as the most active control for PV1 and CV2 as the most active for PV2. If either CV1 or CV2 saturates or is put in Manual mode, the control variable will use CV3 to maintain PV1 and PV2 at the setpoints.
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