| 초록 |
Hazard analysis is one of the basic tasks to ensure the safety of chemical plants.However, it is an arduous, tedious, time-consuming work and requires multidisciplinaryknowledge, and demands considerable cognitive load from the analysts. To overcome theseproblems, there have been attempts to automate this work by utilizing computer technology,particularly in the area of knowledge-based technique. However, Many of the past approachesto automated hazard analysis lack some(or all) of the following desired properties; SAFEGUARD CONSIDERATIONThe existing systems do not consider safeguards. Many hazards, particularly in relativelyuncomplicated situations, can be immediately apparent. So much part of potential hazard isalready known to the designer beforehand. Safeguards are prepared for those kinds ofhazards. But it is difficult for the designer to prepare for all the cases which evolve throughcomplex routes. For the good hazard analysis, it is important to consider the existingsafeguards, to verify their validity and to list hazards which are not covered by thesafeguards. That is fit to the very purpose of performing the hazard analysis. ACCIDENT DIVERSITYThe type of accidents in chemical plants is various, but, compared to that, the existingsystems are limited in the variety of accidents they represent. Generally hazards can beclassified as physical hazards and chemical hazards. The existing system can only deal withlimited parts of them - usually those of physical hazards. CAUSE AND CONSEQUENCE DIVERSITYA malfunction of an unit can influence the whole process via stream integration. So the causeand consequence of accidents must be analyzed from the whole process structure.Furthermore, if one malfunction is analyzed more thoroughly, it can be found that themalfunction is caused by other malfunctions. For example, valve stuck closed is a immediatemalfunction which can cause variable deviation, but this is a result from overtight packing,lubrication dried out, or overtight closure, etc. In order to clarify various cause of faults, therelationship between ultimate malfunction and immediate malfunction must be identified andrepresented. PATHWAY LEADING TO ACCIDENTSAn accident may be said to be the discrete sequence of events. To manage potentialaccidents in chemical process effectively, the pathway from ultimate malfunction(or initiatingevent) to the actual accident should be identified. The existing systems present simply causesand consequences of variable deviation, so it is hard to know what happens during thedevelopment of accidents. VARIOUS HAZARD ANALYSIS REASONINGThe existing systems either infer hazard from variable deviation, or identify hazard bypositing fault. However it, can’t be said which method is superior because both methods aremutually complementary. So if they are applied to the same process, the quality of hazardanalysis will be enhanced.The previous approaches have drawbacks mentioned above due to their limitations incapturing and utilizing all forms of available information. Therefore, it is really important tomake an appropriate knowledge representation which is fit to the objective of developingexpert system.
|
