Page 677 - Dust Explosions in the Process Industries

644 Dust Explosions in the Process Industries

to assess dust explosion hazards in industry and select appropriatemeans of prevention
and mitigation. The system is, in all essentials, based on the German protection philos-
ophy. Wach (1993) presented another expert system designed for the same purpose, but
the technical and philosophical basis was not explicitly stated. A comprehensive expert
system, Dust Expert, developed in the United Kingdom, was presented by Tyldesley
(1993), and the need for quality assurance of such systems was emphasized. Vadera,
Meziane, and Huang (2001) reported on the experience of using the “mural” system for
specifyingDust Expert with regard to the users’ expectations concerning (1) spotting any
inconsistencies; (2) helping manage and organize specifications, including provisions
of easy access to and procedures for updating, adding, and deleting specifications;(3)
helping manage and carry out the refinement process; (4) helping manage and organize
theories; and (5)helping manage and carry out proof.
Hesener and Schecker (1995) developed the expert system ExTrA to facilitate safety
analysis of drying plants. The systematicprocedure implied in the systemconsists of four
steps: hazard identification,hazard assessment, development of a protection concept, and
selection of specific protection methods and technology. Hesener and Schecker (1996)
gave a more-general presentation of ExTrA, which was developed for basic training,
advanced knowledgeretrieval, and hazard assessmentin industry. The systempresented
was regarded as a prototype rather than a final product.
Hesener et al. (1998) and Kraus et al. (2001) developed an expert system to be used
to identify hazards due to the possible occurrence of various types of electrostatic dis-
charges in various process situations. The system, using the very comprehensiveCEN-
ELEC report R044-001 as its technical basis, covers explosive gases and vapors and mists
as well as explosible dusts. In the first phase of system development, available knowl-
edge was collected and structured systematically. In the second phase, the development
of the systematizedknowledge was implementedin the expert system. The system gives
references to existing guidelines and regulations.
Lorenz (1999) presented an expert system for the design of explosion venting arrange-
ments. The system is based on the VDI 3673 venting code, which is very close to the
new European Union code produced by CEN TC 305. The system accounts for the iner-
tia of vent covers and doors and assesses forces acting on these covers and doors. The
extent to which debris is ejected into the surroundingsby destructive explosions is also
accounted for. Lorenz and Schiebler (2001b) presented an expert system incorporating
the four programs-SIMEK, STS, Vent, and Vessel-dealing with the design of explo-
sion doors and lids, ejection of debris, venting assuming “zero mass” vent covers, and
the stability of pressurized enclosures, respectively.
Siwek and Cesana (2001) described the two expert systems WinVent 3.0 and ExTools.
The first provides the information required for designing dust and gas explosion venting
systems according to the National Fire Protection Association (1998) and the Verein
deutscherIngenieure (2000);the seconddeals with safetyrelated to gases and liquids only.
The development of this kind of expert system is a natural consequence of two main
factors. The first is the almost explosive developmentof the performance of personal com-
puters. The secondis the steadily increasingknowledge about ignition and explosionphe-
nomena, which demands a steadily more differentiatedand complex approachfor solving
the practical design problems.
As long as this developmentis conducted by people who are experts not only on com-
puters but also on the physics and chemistry of the phenomena treated, expert systems