Citation

Wilikens M, Burton CJ. Int. J. Ind. Ergonomics 1996; 17(4): 351-366.

Copyright

(Copyright © 1996, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

This paper describes FORMENTOR, a real-time expert system that offers on-line decision support to operators of a complex plant who are faced with unusual and potentially hazardous situations. After the overall project background has been described, the essential requirements of such a system are outlined. The paper will then focus on one of the developed pilot applications, a supervisory and decision support system for operators of an extractive distillation unit of a petro-chemical plant. The most important techniques and models used will be discussed. A number of generic and well defined tasks have been identified for a plant supervisory system like FORMENTOR to allow it to monitor on-line sensor data and detect precursor signs of abnormal plant behaviour, to diagnose the causes of the malfunction and finally to yield operational advice for managing the abnormal situation. This set of tasks include data retrieval, monitoring, diagnosing, assessing the current situation, assessing the consequences of the current situation, countermeasure planning and finally generation of advice. These generic tasks are instantiated in this particular application. In addition, main technical features of this pilot application are a functional model used to provide a global overview of the plant state and to guide the action planning process, a multi-layered structural model used to represent the functional components of the plant in a hierarchical way, and the use of two distinct but complementary reasoning modules for diagnosis, both based on this multi-level model. Of the two diagnostic reasoning modules one, the Heuristic Causal Reasoning module, identifies known problems, looks up the known solutions, and then adapts the implementation of these high-level solutions to the plant state. The other, the Model-Based Reasoning module, uses a more sophisticated model-based reasoning to find the root causes of a disturbance. The developed FORMENTOR system has been installed on an extractive distillation plant operated by BP-Chemicals Ltd. Its performance in responding to real plant upsets has been evaluated. The main results of this testing campaign are also reported.