The dispersion of fugitive emissions from storage tanks

Abstract

This paper presents laboratory experiments of the dispersion and flow field downwind of cylindrical buildings such as petrochemical storage tanks. We consider buildings of height to diameter aspect ratio A= H b/ D, in the range from 1 to 0.5, submerged within deep, aerodynamically rough, neutral and stable boundary layers. Emissions are neutrally buoyant with no significant vertical momentum, releases being made from point sources at heights H s in the range of H b⩽ H s⩽1.5 H b, except in studies with floating roof tanks where the release was from an annulus between the roof and the internal tank wall. Various configurations are examined which include buildings in isolation, in conjunction with bunds (low surrounding walls) and in small groups. Characteristics of the mean velocity and dispersion fields are discussed and compared with results for releases in the absence of buildings and for releases in the presence of cuboid buildings. Dispersion characteristics of the cylindrical buildings are found to be aspect ratio dependent. Further, the presence of bunds results in a significant impact on the velocity and concentration fields leading to considerable reductions in ground-level concentrations.