Investigation on fog formation of LNG ambient air vaporisers

Abstract

Fog formation and mitigation have attracted increasing attention when vaporising cold liquids, such as LNG. The fog formation process during AAV (Ambient Air Vaporiser) operations for LNG regasification is discussed in this study to obtain an in-depth understanding of the effect of both ambient conditions and AAV operating conditions. A multiphase CFD model is applied to simulate fog formation during the mixing of cold AAV effluents and warm & humid ambient air. An operational AAV site is taken as an example to establish the base case of fog formation. Two key parameters, fog bypassing rate and air intake temperature, are monitored to understand the entrainment of cold effluents at AAV air inlet. Parametric studies are conducted to investigate the effect of various air conditions on fog formation comprehensively such as wind direction, wind speed, relative humidity, and AAV operating conditions such as exit velocity, effluent temperature, and air upflow. It is found that the model can help understand the fog formation process and the phenomenon of fog bypassing, which can be used to optimise the AAV operating conditions and investigate the potentials for fog mitigation.