Volatile Emissions from Hot Bitumen Storage Tanks

The purpose of this study is to estimate the fugitive volatile organic compounds (VOCs) emitted from hot stored bitumen and to assess the contribution of these VOCs on the overall emissions in refinery processes. All the usual information regarding VOC emissions from tank storage is based on the storage of petroleum products at ambient temperature (mainly volatile streams such as fuels), and all the calculation systems used to predict or estimate the emissions are based on daily or seasonal temperature variations. Consequently, a dedicated protocol for hot bitumen storage using measurement-based estimations was established. Tank headspace compositions were also determined. Some annual emissions were estimated and comparisons were made with current emission factor-based methods. The atmospheric VOC emissions from hot stored bitumen were shown to be made of residual petroleum compounds. The experiments demonstrated that volatile emissions are more bitumen related than temperature dependent in the studied temperature range. The experiments also showed VOC depletion over time. Storage duration is the predominant factor affecting VOC emission levels. Another main outcome concerns the influence of differences in the manufacturing process between oxidized and nonoxidized bitumens, with the blowing operation decreasing the VOC contents by stripping. Finally, it is shown that hot bitumen storage tanks make a low contribution to the overall fugitive VOC emissions in a refinery process. (C) 2010 American Institute of Chemical Engineers Environ Prog, 30: 102-112, 2011