(46ah) Challenges of Explosion Risk Management in Artic Environments

Fully enclosed platforms utilized in artic climates can present challenges for managing explosion risk.  Generally, modules on modern platforms are built with an “open” wall design.  These open wall designs provide: (1) increased ventilation, which helps to prevent the accumulation of flammable gases within the module; (2) open pathways for flammable gases to dissipate; and (3) open pathways for the explosion to vent, thus reducing the overpressures.  Due to the harsh conditions in artic environments, the outer walls of the platform are solid and enclosed, which prevents flammable gas from escaping during unintentional releases.  Unlike open modules, nearly all mass flow leak rates (including the high frequency of occurrence, low mass flow rate leaks) can fill an entire process area with near stoichiometric gas concentrations at some time during the release.  When ignited, these clouds can produce devastating explosion overpressures.  Enclosed modules also increase the duration of time for which these clouds are present, which can increase the probability of ignition as mechanical ventilation is the only means of diluting and removing the gas vapor.  This study will use FLACS CFD explosion and dispersion modeling to analyze the application of various mitigation techniques to help manage the explosion risk in these enclosed platforms.  More specifically, the effectiveness of soft barriers/partitions (to reduce cloud sizes) as well as partially opening the outer enclosing walls (to reduce cloud sizes and the time that gas vapor may remain in the flammable range) will be evaluated.  Exceedance curves will be produced for various geometry changes to analyze the 10^-4 and 10^-5 per year frequency of occurrence overpressures.