(104h) Study of the Effects of Obstacles in LNG (Liquefied Natural Gas) Vapor Dispersion Using CFD Modeling

Abstract

The new as well as existing design of an LNG terminal requires the evaluation of the potential hazards related with its operation which includes possible release scenarios with the consequent flammable vapor dispersion within the facility (NFPA 59A, 2009); therefore it is important to know the behavior of this phenomena through the application of advanced simulation tools.

Computational Fluid Dynamic (CFD) software provides accuracy and flexibility on simulating the dispersion of an LNG vapor cloud. This CFD tool is used to perform consequence modeling to estimate the exclusion zones for an eventual release scenario in LNG terminals and also other facilities, especially in the cases where the complexity of the geometries within a facility must be taken into account.

The main objective is to acquire a better understanding about the effects that different geometries (obstacles) may have over the LNG vapor dispersion and how much the LFL distance will be reduced in presence of these obstacles. Different scenarios will be simulated to study the effect of the height, shape, temperature, and roughness of the obstacles on natural gas dispersion.

The present paper will perform the simulation of LNG vapor dispersion with obstacles using a commercial software FLACS. This software showed a good agreement between its simulation and the experimental results in a previous validation study performed against obstructed dispersion tests (Hansen et al., 2010). A LNG pool produced by the LNG spill on ground will be considered as the source term for all the simulations. The enhanced mixing of evaporated LNG in presence of different obstacles will be studied.

References:

NFPA 59A: Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG). 2009 Edition.

Olav R. Hansen, Filippo Gavelli, Mathieu Ichard, Scott G. Davis (2010). Validation of FLACS against experimental data sets from the model evaluation database for LNG vapor dispersion. Journal of Loss Prevention in the Process Industries.