The National Maritime Research Institute started 5 year research project on the establishment of synthetic countermeasures against the discharge of oil and hazardous fluid substance from 2011 to 2015. The main purpose of this project is to produce the tool for the environmental risk assessment of the oil discharge from vessels which sank due to the marine accident. The element technologies as the counter-measure against the discharged oil will also be developed in the project.

The element technology as sub-surface application of dispersant for counter-measures will be introduced at the poster session. The first large-scale application has been carried out during the Deepwater Horizon incident in gulf of Mexico in 2010. The experimental set-up consists of rectangular water tank (0.8m×0.8m×3.0m) connected to the oil tank and dispersant tank. The heavy fuel oil was used. Both oil and mixed sample of oil and dispersant have been discharged from the nozzle into the water tank. The video for the behavior of oil and mixed sample has been analyzed by defining the concentration of black and white color. The video has been taken by the high resolution camera. The concentration of 8 different steps between black and white was set in the analysis. The dispersed oil has particular color when dispersed in water and too much dispersant becomes clouded because the dispersant reacts to water. The concentration change has been related with the dispersive performance. The rising-up velocity was also analyzed by PIV (Particle Image Velocity) method so as to ensure the effect of the dispersive performance. The distribution of oil droplets has also been measured and analyzed.

The various percentage of dispersant has been compounded into mixed heavy fuel oil. 1%, 5% and 10% dispersant oil ratio (DOR) has been tried in the experiment. The dispersive area and rising-up velocity after injection of both oil and mixed sample have been compared among them. The dispersive area and rising-up velocity due to difference of DOR has been discriminated. Those parameters can be an index of evaluating the dispersive performance.

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