Experiment using Scale Model of Cargo Tank to Estimate the Concentration of Benzene Gas Emitted from Chemical Tanker During Loading Operation

Abstract

Abstract International Maritime Organization (IMO) recognized that chronic exposure to benzene vapors in air may cause leukemia even if the concentration is very low, such as a few parts per million. To predict the exposure level of crew, it is necessary to investigate the actual conditions of vapor emission from chemical tankers engaged in benzene transfer operation. Since it is difficult to realize experiments using actual chemical tankers in service, scale model experiment was conducted to estimate the concentration of benzene gas emitted during loading operation. The dimension of scale model tank used for experiments is 0.89m in length, 0.39m in breadth, 0.44m in depth and it is 1/10 scale of typical cargo tank integrated in the 499 Gross Tonnage chemical tanker which is usually used for benzene transfer in Japan. Three factors to affect the concentration of benzene gas emitted during loading operation are found from scale model experiments. Primary diffusion mechanism is one-dimensional molecular diffusion advancing in the vertical direction. And the others are eddy diffusion above surface and advection in the vicinity of the tank ceiling.