The extended gravity oil water separation (EGOWS) system uses a tank and siphon system that builds upon the tried and true industry-standard American Petroleum Institute (API) gravity separator.
The API separator is widely used in oil refineries, and while it provides a robust separation process, it generally cannot reduce oil content below 100 parts per million, and therefore is unable to release water straight to the environment.
“EGOWS can remove oil down to 10 parts per million, requires no power and is most useful in situations that are unattended,” said UNSW team member David Tolmie.
“Most of the EGOWS installations to date in Australia have been in electricity substations to eliminate the small but potentially disastrous risk of major spill of oil to the environment.”
The system works by taking in regulated inflows of oily water and extending the time it remains in the separator tank – the more time given, the more oil rises to the surface.
This extended time is managed by keeping the separator in a partially empty state, automatically releasing water via a simple siphon when the separator is full and minimising the chance of oil droplets getting into the separator outlet.
“We were looking for a simpler way of doing things,” said Tolmie.
“One way is to make the tank bigger – and that works – but we realised we could use the existing API separators more productively. The beauty of our concept is that existing systems can be retrofitted with relative ease.”
The EGOWS system has been patented in Australia, America, Europe, New Zealand and Asia by the commercialisation arm of UNSW, New South Innovations, and the design is already being used by Australian companies.
Energy Australia has estimated savings of $A18 million over 10 years from installing EGOWS systems, while Caltex has installed two EGOWS units, which it believes will provide effective and cost-effictive stormwater solutions.
“The cost of an oil spill clean-up can be many times the cost of a separator, which will contain the oil spill automatically,” said Tolmie.
