MODEL-BASED CONTROL OF A PARTIAL BURN FLUID CATALYTIC CRACKING UNIT

A dynamic matrix controller [PMC] has been successfully installed on t he fluid catalytic cracking reactor/regenerator section at RVI's Vohbu rg Refinery in Germany. A very short payback time was achieved based o n increased feed processing and more stable regenerator operations (re duced catalyst addition rates). The controller has 6 inputs (manipulat ed variables) and 13 outputs (controlled variables). The application p rovides an excellent example of the importance of controlling processe s at constraint limits. From the initial day of commissioning the cont roller has stayed online and sustained a service factor of between 95% and 98% over an 11 month operating period. The limiting factor at the moment is the performance of the CO analyser. The controller has prov ed to be robust and operated well with constraints; it has handled dis turbances effectively.