Maplin Sands Experiments 1980: Dispersion Results from Continuous Releases of Refrigerated Liquid Propane and LNG

In 1980, a series of spills of up to 20 m3 of LNG and refrigerated liquid propane onto the sea was performed by Shell Research Ltd. at Maplin Sands in the south of England. Both instantaneous and continuous releases of liquid were made, and some were ignited. Gas concentration and temperature were monitored from an extensive array of floating pontoons up to 650 m downwind, and meteorological profiles were obtained at two locations.Results from the continuous spills are presented; these were performed at liquid flow rates of up to 5.8 m3/min, and in wind speeds from about 2 to 10 m/s. A comparison is made of the measurements with predictions from the dense gas dispersion model HEGADAS II. The propane measurements provide data on dense gas dispersion without the effects of large temperature difference and low molecular weight, which are present for LNG. In general, the model agrees well with the propane data, but is found to be conservative for LNG dispersion.