SOME KEY ISSUES ON A SUCCESSFUL APPLICATION OF REAL-TIMEOPTIMIZATION TO AN ETHYLENE PLANT

摘要

Lyondell and Applied Manufacturing Technologies (AMT) have implemented a real-timernoptimization (RTO) system on the ethylene plant at Lyondell's Chocolate Bayou Facility.rnThe RTO system contains an integrated plant model that is a combination of rigorous andrnsimplified plant section models covering both the olefins and aromatics units. The decision ofrnwhether or not to model a plant section rigorously or simply is based on whether the model isrnrigorous enough to capture the majority of benefits that an RTO system can bring, whilernsimplified to an extent that the plant model represents the needed relations about the plantrnproduction, constraints and optimal moves. As a result, the RTO system can run very robustlyrnsolving 99.9% of the time and implement setpoints at least every 30 minutes (including waitingrntime after setpoint implementation). This type of RTO system responds to plant operatingrncondition changes and active constraint changes more quickly than traditional RTO systemsrnthat run less frequently. An olefins RTO system based on this approach requires less effort inrnthe design, development and implementation phases, and since it is more robust, it requiresrnless effort to maintain.rnThe RTO system working consistently with the advanced process control (APC)rnsystem is a key factor that directly affects the performance and success achieved by the RTOrnapplication. The interface between the RTO system and the APC system* covers setpointrnimplementation, constraint handling, and steady state target coordination. Additional factorsrnaffecting the success of an RTO system include: an effective way to acquire up-to-date feedrnstock composition and pricing information and a reliable operator interface.rnThis paper will discuss this new approach to online optimization as well as the keyrnfactors determining the overall success of the application.