engleski

Control loop optimization on FCC plant in INA Refinery Rijeka

Very few plants use modern software for control quality monitoring, PID tuning optimization, advanced process control (APC) or optimization. The reasons are absence of engineering knowledge and unavailability of practical and robust process control software tools for system identification, PID/APC parameter optimization and control quality monitoring, running plants conservatively due to fear of causing shutdowns and plant problems. Plant management is often unaware on the poor condition of the process control quality in the plant because of absence of easy methods to trend and quantify the control quality metrics. The first step in improving the plant control quality is to install online/offline control quality monitoring software. The second step is to analyze process data on poorly performing control loops and identify the system dynamics. The final step is to calculate the new and improved controller or APC tuning parameters. Following these three steps systematically can tremendously improve plant’s control quality and in turn, the plant’s profit margins. The new process control software tools for quick and easy system identification using available data from the plant’s historian can help tremendously improve the control quality and the plant’s profit margin. It is possible to analyze multivariable systems, complex, nonlinear and slow processes with long dead times and long time constants commonly encountered in petrochemical processes. This case-study comprises control loop diagnostics, analysis and optimization within the INA Refinery Rijeka at the fluid catalytic cracking plant, particularly debutanizer column. During process control loop diagnostics and optimization procedure all control loops found in manual have been analyzed and finally switched to automatic control mode. Several control loops are tuned in consequence of increased stability of the entire plant. Moreover, excessive movement and fluctuation of control valve is reduced. The overall debutanizer’s control system performance is significantly improved which ultimately has a positive effect on product quality and energy consumption thus proving application of control system diagnostics and optimization usefulness.

FCC plant; monitoring and process control diagnostics; process control tuning and optimization

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