Multiple Tank Explosions at Refinery Plant: A Case Study

Multiple Tank Explosions at Refinery Plant: A Case Study

Author: Elmar Zimmermann

In 2006, several explosions occurred at a refinery plant in Spoleto, Italy, resulting in four workers losing their lives. The plant processed crude olive pomace oil to obtain edible olive oil. Crude olive pomace oil is obtained as a by-product of virgin olive oil production: After the olives are pressed, further oil is extracted from the cake using a solvent, usually hexane. The miscella (oil-hexane) is then distilled to remove the solvent from the extracted oil. Crude olive pomace oil is usually treated, stored, and transported as an edible-like product. Therefore, neither the residual amount of hexane, still present in the oil after the extraction phase, is taken into account nor are its strong effect on the flammability of the oil and the consequent safety implications.

Paola Russo, Sapienza University of Rome, Italy, and colleagues, who acted as technical experts for the Prosecuting Attorney, present a detailed analysis of the causes and consequences occurred at the plant: Workers were welding the roofs of a crude olive pomace oil tank when it exploded. A pool fire spread throughout the tank farm until roughly 1 h later, two other reservoirs exploded causing the launching of missiles to a distance of 60–80 m and a huge fire that extended throughout the tank farm. The team conclude that the explosion was caused by the unusually high content of hexane in the crude olive pomace oil and, hence, by the inefficiency of the desolventization process.

By analyzing the causes of the incident, necessary actions were proposed to avoid the recurrence of similar events or, at least, reduce their frequency of occurrence.


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