The plant where I'm employed runs a small distillation column that's a little challenged by high rates. The objective of maximum product purity of the overhead stream causes ops to increase reflux, but the column packing can't handle it and we start seeing vapor bypassing - big swings in packing DP. Can I use MPC to maximize reflux up to a constraint on DP "stability"?
The DP measurement employs three individual transmitters - I believe they are all equipped with the diagnostics (SPM) license. I haven't studied them yet to see if SPM might reveal (and smoothly trend toward) a maximum, but in either case the CV/MV relationship is nonlinear when the limit is reached.
The other side of the coin would be cutting reflux in reaction to a "false positive". We don't want that either.
Fishing for clever thoughts and experiences from the community before engaging in more trial-and-error . . .
-JR