VOC emission source strengths of tankers during refuelling activities determined by spectroscopic remote sensing and inverse dispersion modelling

摘要

Tankers are a wide spread and important emission source of VOC's. Up to now emission data are available from measurements inside the storage tanks to investigate explosion protection only. Different emission reduction systems are under discussion such as vapour recovery units. The environmental impact of these alternatives shall be investigated. The VOC emission of tankers were investigated in a river harbour. Fence-line monitoring by Differential Optical Absorption Spectroscopy (DOAS) was performed to investigate different emission sources during activities of tankers in harbours. Benzene, toluene and p-xylene concentrations were measured by a mono-static DOAS using 3 retro-reflectors. The inverse method was applied on the basis of these non-intrusive measurements of effluent concentrations in the exhaust plume and meteorological measurements to determine the emission source strengths. Inversion of effluent's dispersion was performed by a Lagrangian model driven by wind fields on the Eulerian model MISKAM considering influences from buildings and the orography upon the streaming fields. The emission source strengths were determined from unloading and loading of gasoline, from ventilation of storage tanks of tankers into ambient air which is of common practice if the tankers are operated without load or if the tankers are to be refuelled with a different product than before and from using the land-site gasoline vapour recovery unit in a tank farm for ventilation.