Evaluation of Key Parameters for Designing Effective Water Curtain Systems for LNG Facilities Using Computational Fluid Dynamics

Concerns over public safety and security of an accidental LNG spill have motivated the continued study of LNG mitigation measures. Forced dispersion of LNG vapors using a water curtain system has been proven to be effective in reducing the LNG vapor exclusion zone by enhancing the dispersion. Currently, no engineering criteria for designing effective water curtains are available mainly due to a lack of experimental data. Different experimental conditions and the discrepancy in defining the parameters make it difficult to understand the complex interaction of the water droplet-LNG vapor system.

This work applies computational fluid dynamics (CFD) modeling to evaluate different key parameters involved in dispersing LNG vapors using an upwards-conical water spray. A forced dispersion model based on an Eulerian-Lagrangian approach was used to model the water spray system. The Eulerian-Lagrangian approach calculates momentum and heat transfer by considering the various effects of the droplets (discrete phase) on the air-vapor mixture (continuous phase). The results were validated against the March 2009 Mary Kay O'Connor Process Safety Center (MKOPSC) outdoor LNG spill experiments conducted at the Brayton Fire Training Field. Consequence assessments on the influence of various properties of water curtain systems were conducted. On the basis of the findings, the effect of different droplet sizes, droplet temperatures, and installation configuration of water curtain systems are evaluated. Finally, the potential for applying the CFD application in providing guidance for setting up the design criteria for the water curtain systems as an integrated mitigation measure for LNG facilities are discussed.