The Effect of Turbulence on the Evaporation of LNG Spills on Water

An important element of the overall risk of near-shore and offshore LNG operations is the behavior of spills on water: how the spill first interacts with the water at the point of entry, how the liquid pool first forms and spreads and how the emanating vapors disperse. Several models exist for estimating the behavior of an LNG spill on water, which all include a number of simplifying assumptions. One important component of these models, necessary for the successful prediction of LNG pool spread and formation of vapor clouds, is the rate of evaporation of LNG, which will be heavily influenced by the turbulence intensity of the water surface.

The present study seeks to address the current lack of direct measurements of LNG evaporation rates on water under controlled levels of turbulence. A turbulent water surface is generated with an upward pointing submerged jet. The turbulence intensity is adjusted by varying the jet velocity. A cryogenic liquid is poured onto the surface, and the evaporation rate is measured experimentally. Tests have been conducted using liquefied nitrogen, subsequent tests will involve LNG. The water temperature and salinity may also be varied to determine their effects on the evaporation rate. The purpose of these measurements is to provide new data to improve existing models for the rate of evaporation of LNG spills on water, to aid the industry in managing operational risks, and to help in accurately implementing the technical recommendations put forth by regulatory agencies.