Reviewed existing techniques for fault detection and diagnosis
Merge three existing techniques to develop fault dictionary and logic inference system

Utilizes disturbances detected using step-test model of process, similarity between observed alarm sequence and known fault sequences, and expert knowledge

Forward chaining used for process modelling, backward chaining used to validate fault hypothesis

Prototype built for Fluid Catalytic Cracking unit, able to detect many faults including:

Catalyst circulation

Catalyst loss

Coking

Flow reversal

High regenerator temperature

After burn

Hydrogen blistering

Product quality

Software warns operator of any detected faults, and provides recommendations needed to prevent incident