Consequence analysis in industrial organizations containing H₂S gas through accident scenarios based on chemical source selection

Abstract

H2S gas emissions occur in various processes, especially in the purification of polluted waters, mining, and petroleum refining processes and this extremely dangerous chemical has serious toxic emission, explosion, and fire effects. These physical effects vary considerably depending on the source strength. Therefore, consequence analyzes based on source strength models are critical components in the process of assessing hazards. In this study, a consequence analysis was performed with accident scenarios related to different sources of H2S gas. ALOHA 5.4.7 and EFFECTS 8.0.1 Software were used for physical effects modeling. Modeling studies were conducted on direct source (continuous release:100 m3/s, 5 m3/s), puddle source (100 m3, 5 m3), tank source (vertical‐horizontal cylindrical, spherical, 1.57 m3), and gas pipeline source with ALOHA Software. Possible Gas LOC (Levels of Concern) scenario Leak (G3) and Gas LOC scenario release in 10 min (G2) scenarios were studied with EFFECTS Software. When the results of both software were compared with each other, it was seen that the effects of thermal radiation and explosion were of similar order and value, and the toxic effect values were very different from each other. Both software allow for a release above ground level for gases that behave as neutrally buoyant. The main difference between the dispersion models used in the software is that the gas is assumed to behave as non‐interacting ideal gas in ALOHA, but in EFFECTS deviations from ideal gas are considered. And, ALOHA dispersion models use surface roughness lengths in a limited fashion and only include 60‐min AEGLs. ALOHA does not account for topographic steering or winds that vary with time in EFFECTS. It can be said that the results of the ALOHA Software are more conservative than the EFFECTS Software.