Model predictive control

摘要

IN THE OLD days, we used small and large valves with the idea that the small valve would extend the rangeability of the manipulated flow for low loads. The valves were split ranged with the split range point set at the classical value of 50%. The split range was typically done in the positioner. Of course, the big valve tended to get stuck in the seat where the friction was highest, especially if the valve was designed for tight shutoff or the plug stayed in the seat for long periods of time.