A method of analysis for gas explosions: H2Se case study

This paper presents a methodology for conducting a simplified gas-explosion analysis when there are uncertainties about the amount of fuel involved an d the mode of combustion. The methodology is illustrated by a case study of an explosion of a cloud of hydrogen-selenide (H2Se), nitrogen and air. Hyd rogen-selenide (H2Se) diluted with N-2 is used in a reactor vessel to produ ce solar cells. An explosive mixture could be created if the reactor vessel failed and its contents mix with ambient air. Mixtures of 20% or 6% H2Se i n N-2 were considered as feedstock into the reactor. It was determined theo retically that an explosion involving either mixture would challenge the re actor room's integrity. However, it is unlikely that a local ignition will propagate in the dilute 6% H2Se mixture, because its adiabatic flame temper ature is only 850 K; the 20% mixture is borderline flammable. Because of th e proximity of personnel to the reactor room and the high toxicity of H2Se, any damage to the room boundary is considered unacceptable. To prevent acc idental mixing of H2Se with air in the reactor, a nitrogen buffer was insta lled between the reactor vessel and the ambient air. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.