Chemical herding of weathered crude oils for in-situ burning

Abstract

Mid-scale ISB experiments were conducted in a large water-basin (20 m 2 x 1 m) in order to assess the applicability of chemical herding of weathered crude oil spills on water in association with in-situ burning (ISB). A silicone-based chemical herding agent, OP-40, was used to confine, or herd, three different crude oils (Siri, Grane and Oseberg blend) at various weathering degrees. The herding agent was capable of obtaining the minimum required oil slick thickness for ignition and subsequent flame spread in most of the experiments, but not for the strongly weathered oils. Also, the herding agent was capable of re-thickening the oil slick after flame extinction. The burning efficiency results indicate that the method can be viable for ISB with herders at a larger scale, and suggest that the burning efficiency scales with the amount of crude oil. Sinking behaviour of residues was also observed and quantified, as such a behaviour can pose a serious environmental threat in real scenarios.

Experimental study of thickening effectiveness of two herders for in-situ burning of crude oils on water

“…In all cases, OP40 was more efficient than TS6535. When comparing ANS against Grane, both herders turned out to be less effective for Grane (apart from fresh Grane with OP40), which is in contradiction to previous findings [33,34]. In short, the present results add more discrepancy to the results from the literature (see Section 1).…”

“…As a consequence, the viscosity and volume of oil increase dramatically [24,26], and this also leads to changes in the surface tension of the oil [27,28], all of which are challenging the successful use of herders. Despite these known challenges, only a few studies have been undertaken with herders and weathered crude oils [29][30][31][32][33]. These experiments were conducted across a range of test scales (in laboratory conditions and in the outdoors), as well as in the field.…”

“…The water temperature and water salinity have been reported to have contradictory results on both herders [4,21,29,30,[34][35][36][37]. The pre-spill application showed that both herders are more efficient in holding thicker oil thicknesses than post-spill application [4,33]. The efficiency of both herders can also be defined as a function of the thickening duration.…”

“…Even though it is important to evaluate whether the herder is still active after burning, the consequences of the ISB process on the herding agent are not known. It has been reported that the oil slick undergoes a dynamic process where it expands and contracts during ISB with herder as confinement [14,20,33,39] ( [33] and [39](accepted)). If the oil slick expands during burning, the oil slick thickness reduces, thereby increasing the heat losses towards the water bed.…”

Efficient and Fast Removal of Oils from Water Surfaces via Highly Oleophilic Polyurethane Composites

“…Fuels, in the form of light hydrocarbons, for example, tars, grease, and diesel oil, or as heavy hydrocarbons, such as kerosene, gasoline, and jet fuel, together with fats, lubricants, and motor oil are increasingly in demand by the market [ 11 , 12 ]. There are many chemical, physical, and biological methods to remove oils from contaminated water [ 13 ], including oil dispersant [ 14 ], in situ burning [ 15 ], filters [ 16 ], reverse osmosis [ 17 ], gravity separation [ 18 ], electrocoagulation [ 19 ] and electroflotation [ 20 ]. Sorption is probably one of the most used methods because oil sorbents fall into two very broad categories: synthetic, such as polyanilines and polypyrrole-silica polymer composites [ 21 , 22 ], and natural adsorbents, such as bio-based aerogels and natural adsorbents based on sawdust [ 23 , 24 ].…”