Experimental Analysis of n-Butanol Behaviour in Seawater due to Chemical Release from Marine Shipwreck

Abstract

This paper is a contribution to the characterisation of chemicals solubilization in seawater due to marine accident. Experimental tests were performed at large laboratory scale in a large seawater column (CEC) to investigate the mass transfer process for n-butanol release. This column is fitted with glass windows in order to visualize the chemical behaviour in the water column. Experiments were performed with n-butanol at low mass flow rate to perform a droplet flow and to evaluate the solubilization processes at the droplet scale. The mass transfer occurs in the boundary layer which develops on the droplet surface. This solubilization layer detaches from the droplet and generates a persistent cloud of solubilization in the droplet wake. The results on the variation of droplet diameter along the CEC show a decrease of a factor 1.64 which corresponds to a volume loss close to 80 %. Physics of the two phase flow is presented and highlights the solubilization processes in the wake of the droplets with trailing edges vortices. The comparison of measurements with Clift’s correlation (Clift, 2005) for droplet rising velocity shows a good agreement for data obtained at the top of CEC but large discrepancies occur at the bottom. This difference can be attributed to the droplet flow regime which corresponds to a non-stationary regime with droplets rising to the terminal velocity.