17:00 - 17:30
Wednesday, 18 September 2019
T2.6 Jet Fire Consequence Analysis
The recent interpretations of 49 CFR 193 regulations by the US Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA) on flammable cloud dispersion have significantly influenced the design approach for new LNG facilities and expansion projects at existing facilities. In particular, PHMSA now requires that certain jet fire hazards resulting from high pressure flammable releases must be addressed as part of the LNG plant’s hazard evaluation. This has increased the emphasis on evaluating a wider range of potential jet fire scenarios than previous risk analyses may have suggested. This increased emphasis has challenged the available tools in calculating jet fire consequences at LNG facilities.
Current jet fire consequence analyses rely almost exclusively on empirical models that use a simplified conical flame geometry and fixed emissive power to determine the thermal radiation load. The available empirical models provide acceptable radiation load estimates for hypothetical scenarios that are comparable to those used during model development. The model development tests are typically small scale jet fire experiments. The accuracy of empirical models for larger jet fires has not been yet assessed. Computational Fluid Dynamics (CFD) represents an alternative solution for evaluating jet fire radiation loads. CFD has been used historically in a wide variety of applications, including but not limited to the aeronautics and automotive industry, the biomedical industry, and in a wide range of industrial applications involving heat transfer and fluid mechanics. With recent advancements in computer power, computational fluid dynamics has become a mature tool that can be used reliably for the evaluation of the impact of fires. During the facility design process, CFD offers flexibility in evaluating the effect of design changes and provides information to assist in making design decisions.
This paper will describe the current state-of-the-art for jet-fire consequence analysis as well as review the publicly available experimental data. A few representative test cases will be used to compare empirical methods and CFD results to published experimental thermal radiation data. The paper will include a parametric study to characterize the effect of leak size on the jet fire size and thermal radiation output. The authorship team represents experts in fire science, risk-analysis and computational fluid-dynamics, and have years of experience in the consequence analysis for the Oil & Gas Industry.