Very large LPG plants have been built in recent years. Process cycle selection depends on feed gas composition and product package. Most LNG plants, however, use quite similar liquefaction cycles and unit sizes: LNG delivery contracts require high plant reliability, allowing of only' gradual developments. Factors affecting process selection for deep removal of feed gas contaminants will be reviewed. In the shipping phase, special and often dedicated ships are used. Safety is of prime importance during the transportation. Also storage tanks with enhanced safety are being developed further, using the experience gained. Work on new codes has started. Guidelines for siting new terminals or adapting existing terminals to new circumstances are under discussion between industry and authorities. Development of sensible traffic regulations, together with adequate port designs, should eliminate undue risks due to collision or grounding.

Since rigid engineering rules and regulations do not suffice in all circumstances, in many cases mishap scenarios are used to assess potential hazards. Mathematical models for these calculations have been created, often supported by case histories or large-scale tests. A number of models are generally accepted for hazard assessment.

No consistent approach for the evaluation of such assessments has yet been established. The perception of the risk by the public is under investigation.

Résume. De très grandes usines de liquéfaction de gaz de pétrole ont été construites ces dernières années. Le choix du cycle d'opération dépend de la composition de gaz d'alimentation et de l'éventail des produits.

Cependant, la plupart des usines de liquéfaction de gaz naturel utilisent des cycles de liquéfaction et des dimensions d'unités plus ou moins semblables: les contrats de livraison de GNL exigent une grande fiabilité de l'usine, qui ne devra permettre que des développements graduels. Les facteurs influençant le choix du procédé d'élimination radicale des polluants du gaz d'alimentation seront passés en revue.

Dans la phase des transports maritimes, on utilise des navires spéciaux et souvent affectés exclusivement à cet usage. La sé

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