A case study: An explosion in a milk spray dryer, CAPSA, NW Spain

European Standard EN 14491 (2006): “Dust explosion venting protective systems”, based on German Standard VDI 3673 (2002): “Pressure venting of dust explosions”, Verein Deustcher Ingenieure, specifies the basic design requirements for the selection of dust explosion venting protection systems.In this study an investigation into the efficiency of venting surfaces in accordance with Standard EN 14491 has been undertaken to check the validation of the same. Thus, the application of the standard to an actual case of an explosion in a milk spray dryer has been studied, taking into consideration the explosive characteristics of products treated in this type of installation and their venting requirements.The results obtained indicate that, in specific situations – such as the effects of turbulence, particularly in the cone, or dust layer self-ignition – the European Standard could underestimate the venting surface requirements needed to alleviate possible excess internal pressure in order to avoid injury or structural damage to spray dryers.

► Standard UNE-EN 14491: Dust explosion venting protection systems has been revised.
► A study of venting surface requirements in a conventional spray dryer has been undertaken.
► The venting requirements study has been applied to an actual case related to a dairy plant dryer in NW Spain, where an explosion took place.