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.