Results of Testing of Oil Skimmers with Diesel and Hybrid Fuel Oils in Cold Seawater

SUMMARY Determining the ability of currently available skimmers to collect new types of diesel, including low sulphur marine gas oil, wide range diesel oil and hybrid fuel oils, is of great importance for preparedness against acute pollution. To be able to make operational assessments of which oil skimmers are best suited to a given situation, we must know how the skimmers work on these diesel and hybrid fuel oils. We have tested various oil skimmers in different oil types. Four different diesel and hybrid fuel oils have been tested: a marine gas oil, a wide range diesel oil and two hybrid fuel oils. Three oil skimmer types were tested. The types are with discs, brushes and adhesion belts. The tests are performed with natural seawater at water temperatures corresponding to winter temperature (0–2°C). Capacity tests have been performed on MGO, HDME 50, ULSFO and WRG to find out how the oil skimmers work in these types of oil. The skimmers were first tested in a restricted basin with a thick layer of more than 20 cm of oil, so that pure oil and only small quantities of water were taken up. The skimmers and oils were then placed in a boom in the basin. A current was applied in the water, which caused a thickness of oil to build up around the skimmer. During our testing the operator ran the skimmers at optimum performance, so that maximum collection and efficiency were achieved. The results gave us the answer that the selected skimmers work in MGO, HDME 50 and WRG. Which skimmer are chosen will vary depending on what is wanted. It is possible to increase the capacity of the skimmers, but this would have a negative effect on efficiency, since the total quantity taken up will be higher. None of the skimmers worked well in ULSFO. This oil has a high point of solidification, which meant that the skimmers did not have a sufficient inflow of oil to work with.