PID control loops are inherent to process automation and contribute majorly to optimum performances (production and energy consumption) of the plant. PID loops in process plants are initialized and parameters are set during commissioning which do not stay stable due to changing input /output process conditions and equipment wear. Hence generally, most loops are not run in AUTO mode or they are sub-optimally tuned affecting their overall performance. Typical process plant survey shows that around 30% of the PIDs run in manual mode (open loop) and almost 50% of the loops which are set in AUTO mode operate at less than 70% efficiency (due to sub-optimal tuning or control valve related issues). Hence, there is always a scope for increasing utilization and optimization of PID performances which directly contributes to reduced process variability and increased productivity (enhanced average production and reduced specific power consumption).
¤ISSUES related to PID loops you WANTED to but COULD not KNOW..
* Are my loops being used (asset utilization/idling)?
* Are my loops controlling WELL to meet process needs?
* When to and How to RE-TUNE the PID loops?
* Are my actuators /valves working excessively?
* Why are my PID loops oscillating?
* Are components sufficient to handle higher targets?
* Which control logic is better for my process?