HYDROGEN-FLUORIDE SOURCE TERMS AND DISPERSION

Assessing risks in the petrochemical industry involves understanding t he potential behaviour of accidentally released clouds of various subs tances. Anhydrous hydrogen fluoride (HF) poses a particular problem. O n the one hand its chemical reactivity is a severe hazard, and on the other, its complex thermodynamic behaviour means that it is difficult to model accidental releases in order to estimate the hazard. In this paper we examine the expected behaviour of hydrogen fluoride clouds us ing the code DRIFT, and contrast it with that of substances which are easier to model. A comparison is given between results from DRIFT and from the Goldfish HF field trials. Furthermore, we show that the homog eneous equilibrium model for the thermodynamic properties of the cloud can describe quite complicated phenomena and that atmospheric humidit y, while less important for other substances, may be an important fact or in hydrogen fluoride dispersion. This is illustrated by examining t he effects that atmospheric humidity may have had on the Goldfish tria ls had they been conducted in less arid circumstances.