Since the Deepwater Horizon spill (2010), the controlled In Situ Burning (ISB) of oil has demonstrated to be a possible solution to treat offshore oil spill. As other techniques usually deployed (mechanical recovery, dispersion), ISB efficiency depends on various parameters such as the oil nature, its evaporation degree, water content. In order to assess the influence of these parameters on the ignitability and burning efficiency, an experimental device was developed at Cedre. The burning bench comprises a burning cell which was created to avoid any boilover phenomenon. Glass barriers, specific hood and plume exhaust system complete the device to ensure safety conditions. Burning tests are conducted on a 100 mL volume of oil sample. During the combustion, the flame is characterized by using various temperature probes set at different heights. In addition, temperature of seawater is also recorded during each test. A gravimetric impactor is mounted in the hood to collect continuously the particles produced during the burning and afterwards to quantify the PM 2.5, PM 10 and PAH content in the soot. At the end of a burning test, residues are collected and quantified after solvent extraction. Different analyses are then performed on the residues: density, viscosity, simulated distillation, chemical family separation (saturates, aromatics, resins, asphaltens), PAH and alkanes distribution and content, … Potential PAH transfer from the oil to the water column is measured after SBSE (Stir Bar Sorptive Extraction) of water samples and quantification by GC-MS.
During the burning bench development, many tests were performed on different products (light refined products, fresh crude oil, weathered crude oil, heavy fuel oil, …). The preliminary results highlighted a very good reproducibility of the tests. For the refined product, more than 70% of the product burnt. For most of the fresh crude oils tested, the burning efficiency was between 50 and 60%. While testing heavy fuel or weathered product, the burning efficiency never exceeded 40%. In addition, different burning techniques were investigated such as igniter efficiency, compressed air influence, thermo resistant sorbent efficiency, …