Hydraulic analysis of oil spill control systems at electrical transformer stations

James Li, Celia Fan

Thursday 2 july 2015

16:40 - 17:00h at Europe 1 (level 0)

Themes: (T) Special session, (ST) Oil spill modelling

Parallel session: 13J. Special session: Oil Spill Modelling

Transformer oil (mixture of paraffins, naphthenes and aromatic compounds) is used to increase the efficiency of the electrical voltage transfer and reduce the moisture and air at electrical transformers. Each year, there is a high probability of spilling transformer oil accidentally from electrical transformer stations to the water environment in Ontario, Canada. In order to control these spills, oil spill control system are installed at electrical transformer stations. These on-site oil spill control systems, either electrically- or hydraulically-based, use the concept of different specific gravities between oil and water for oil separation and containment. It is also assumed that the trapped transformer oil in the oil spill control system will be held for a short period of time and subsequent cleanup mechanism will remove the spilled oil. At a non-staffed transformer station, a sudden surge of oil spills may be trapped by its oil spill control system (designed according to the specifications of American Petroleum Institute for oily wastewater). However, the trapped transformer oil may not be cleaned up right away and may be flushed out during subsequent severe rain storms. The objective of the research project is to investigate oil trapping performance of the oil spill control system at a Hydro One’s transformer station near the City of Burlington, Ontario, Canada. It focuses on the analysis of oil trapping performance of this system during a spill event as well as during a subsequent severe storm event. Using a scaled physical model (1:12) and the actual transformer oil used at the station, the performance of this oil/water separator system was analyzed. The study results indicate that (1) oil/water separation process of a sudden surge of spilled oil is different from that of an oily wastewater; (2) the spilled transformer oil in the physical model can be retained by the oil control system under high flow conditions; and (3) the number of oil/water separators at the transformer station is adequate to prevent flushing of trapped oil even up to a 100 year storm event.