Risk Analysis of a Supercritical Fluid

The Supercritical Fluid Extraction (SFE) technology is currently used in many industrial fields thanks to the advantages that it can offer. Experimental tests are carried out for different purposes such as decaffeination of coffee/tea, extraction of aromas and herbal flavours as well as spices, extraction of fats and oils, extraction of cholesterol and extraction of alcohol from beverages. SFE plants safety is closely linked to the high pressure they operate, a condition that can lead to a risk status for plant operations and above all workers. For this reason it is necessary to adopt preventive safety measures and a risk analysis is the means that allows to define and examine hazardous scenarios in order to identify safety devices. Risk scenarios related to an extraction plant as explosions are analysed through methods based on indices determination such as the Fire and Explosion Index (F&EI), the Safety Weighted Hazard Index (SW&HI) and the Probit method. This work presents the risk analysis of a SFE plant named “Luwar” using the commercial software “Phast & Safeti” provided by the DNV GL Company. In the plant is used CO2 as extraction fluid and the process purpose is valuable compounds extraction from microalgae. The risk analysis is performed on the extraction vessel considering the plant placed inside a structure (indoor condition). The results allow to identify two risk parameters, i.e. the distance and the area within which CO2 concentration in the air assumes a value considered unsafe for human health. On the basis of the outputs it is possible to identify the safety system to be adopted in order to limit the damage deriving from the occurrence of a risk situation.