Implementation, parameters calibration and field validation of a Closed Loop Performance Monitoring system

The paper illustrates the main features of a performance monitoring system which supervises more than 1200 loops of refinery plants. The system analyses data recorded by the DCS during routine operations and originates verdicts about the performance of control loops; also, indications of low performance causes and different strategies to adopt (retuning, valve maintenance, upstream actions) are given. First, the architecture of the system is illustrated, and characteristics of modules which accomplish different tasks of data acquisition and transfer, system configuration and priority assignment, performance analysis and verdicts emission, database query and operator support, are described. A synthesis of main techniques adopted in the system for stiction detection, process identification and performance evaluation, is also reported. The procedure for calibration of threshold values of key parameters, in order to match verdicts issued automatically by the system with operators evaluations and to avoid false alarms, is also discussed. Examples of results achieved from field validation are then presented, with illustration of loop performance before and after actions suggested by the monitoring system.