Giving New Life To Used Water: This Canadian Refinery Is Closing the Cycle On Its Water Consumption
August 18, 2016
GE Reports Canada
In 2013, Federated Co-operatives Ltd. marked a milestone at its Co-op Refinery Complex in Regina — the completion of a $2.8-billion expansion. It was a major achievement for the refinery. It increased production by 30%, to more than 130,000 barrels a day— enough to cover the entire 71-kilometre trip from Regina to Moose Jaw, if put in barrels laid end to end.
But the expansion created a new challenge: Producing more oil also meant the refinery consumed more water, potentially enough to exceed its provincially regulated allocation for withdrawals from the local aquifer. The refinery could cover the gap with water from the City of Regina. But that would only be a temporary fix. Refinery leaders wanted a permanent solution.
Their answer? The creation of a ground-breaking water-recycling system — designed and built in collaboration with GE — that features cutting edge applications of GE’s membrane bioreactor and ZeeWeed* technologies for the oil-refining industry.
“Our wastewater improvement project allows us to be efficient and sustainable by recovering every drop of water,” says Gilbert Le Dressay, the Co-op Refinery Complex’s vice-president of refinery operations. “With GE’s technology, the Co-op Refinery Complex will clean and recycle all of its wastewater… to conserve water for Regina and the entire province of Saskatchewan.”
Oil refining and oil upgrading are water-intensive processes. The Regina complex uses an average of 1,600 gallons of water per minute (more than 7,000 litres), for tasks that include generating steam, making hydrogen and cooling. Thus, it’s not hard to understand the appeal of recycling water over simply treating and discharging it.
The process at the Co-op refinery, which cost approximately $200 million, involves five stages. The first is the separation of oil and water by gravity in holding tanks, skimming oil off the top as it floats above the water. Next, the separated water is put through a dissolved-gas flotation unit. There, microscopic bubbles of nitrogen are pumped up through the water, binding with suspended oil particles and bringing them to the top of the unit where they are removed. (Recovered oil in both the separation and flotation processes are returned to the refinery for processing.)
After separation, the water moves on to a GE membrane bioreactor, the third step in the process, where specially designed bacteria break down volatile organic compounds and ammonia. This stage improves the quality of the water and reduces odors associated with oil refining. The water is then filtered through GE’s ZeeWeed heavy-fibre membrane technology to remove suspended solids. “At that point the water is pretty clean,” Le Dressay says.
In the fourth stage, excess biomass from the bioreactor process is sent to a centrifuge to separate and return bacteria to the reactor, and to recover any water so that it can be fed back to the recycling process.
“What you have now is very, very clean water,” Le Dressay says. But there’s one last step: multimedia filtration to soften the water and remove any remaining solids that might collect on equipment and interfere with their operation.
Le Dressay notes that not all the water entering the recycling process makes it to the end as the water being utilized for steam generation must be of the highest quality. About one-third is rejected along the way, notably at the final multimedia filtration stage. But the remaining two-thirds is enough to meet most of the refinery’s water needs for steam generation, its largest single water use.
The benefits of the refinery’s water-recycling system are many. First, it ensures the facility’s need to draw on the local aquifer is within always within its regulated allocations — even with the refinery’s expansion. Moreover, it eliminates the need to use City of Regina water, freeing up capacity within the city’s own water-treatment infrastructure. With the elimination of city water, the refinery will free up the equivalent water usage of 3,100 homes in the City of Regina on an annual basis.
The system also significantly reduces the refinery complex’s water footprint and eliminates odors from volatile organic compounds that emanate from water-holding ponds onsite further reducing the refinery’s environmental footprint
Looking further ahead, the Co-op Refinery Complex’s investment in water recycling stands as an example to the refining industry of new, more sustainable ways to manage water in their operations. “What it says to other people in our industry is that it can be done,” Le Dressay says. “You can run the hardest oil to treat in the industry and you can take the water that comes from that and reduce your water footprint. You can run that water over and over again.”
*Trademark of General Electric Company; may be registered in one or more countries.