, Duration: 12:45*Enlace a Spanish version
Materials: [ ttceENG.pdf]
This video presents the problem of a control case study of a system with two tanks and two heating elements, built with the purpose of diluting a certain reagent in water; the reagent must be supplied downstream at a certain temperature. The demanded downstream flow will be considered to be a disturbance. The point of operation will be set to diluting 1 liter of reagent in 5 of water (concentration 1/6 at output).
First, the selection of primary references is discussed: obviously, temperature and concentration in tank 2 are in the set, because that is what the process is built for. A primary level reference is also placed, for safety and so that the residence time of the fluids has less variability (but, well, residence time will depend on flow rates, so it will not keep constant anyway).
Second, the presence of four manipulated variables is discussed: reagent valve, solvent valve, exchanger in the inlet pipe, and heater in the outlet tank.
There are seven sensors, but in this video, we first consider choosing as sensors only those of the primary references (temperature, concentration, level) and thinking about a multi-loop strategy. By “common sense”, it is argued that the water flow will be used for level control, the reagent flow will be used for concentration, and the heater in the outlet tank will be used for temperature.
If you want model-based rather than “common sense” detail on multiloop
pairings in the level and mixing subsystem, refer to video [
The excess of manipulated variables and sensors can be used to improve
performance in cascade, ratio and feedforward structures, discussed in the video [
*Link to my [ whole collection] of videos in English. Link to larger [ Colección completa] in Spanish.