Gathering Steam: High-Tech Evaporators Help Oil Sands Operators Recycle Liquid Waste
November 5, 2013
There are now more than 7 billion people in world who need access to energy and clean water. Innovators like Bill Heins have spent the last two decades developing advanced systems helping to minimize water usage and recycle waste water from water-hungry industries like power generation and oil sands mining.
In the early 1990s, Heins was a young chemical engineer working for a company called Resources Conservation Co. International, now part of GE Power & Water, which supplied water treatment technology for power plants and heavy industry. Water demand and discharge created by a rapid power plant growth along the Colorado River was putting fresh water resources under stress. States along the Colorado noticed and introduce new regulations to control it.
The regulations posed a challenge for the power industry. The plants needed millions of gallons of water every day to remove excess heat from its turbines and generators. Working fast, Heins and his colleagues developed an evaporation system that allowed their customers to recycle and reuse nearly 100 percent of the water they needed. “It nearly eliminated waste water discharge and minimized the need for fresh water,” Heins says. The system also scrubbed naturally occurring salt dissolved in the water, which, in some cases, could be used on the roads in the winter.
The success got Heins and his team thinking about other applications. A thousand miles from RCCI’s Seattle headquarters, Canadian industry was mining huge deposits of oil sands. The operators developed a new mining technique called steam-assisted gravity drainage (SAGD) to recover oil locked in bitumen deep underground. The method, which is sometimes called in situoil recovery (“in place” in Latin), pumps hot steam inside an underground bitumen reservoir through a horizontal well. The steam “melts” the clay-like bitumen, and a mix of oil and water then flows to the surface through a second horizontal well where the oil is separated from the water.
At the time, the system wasted as much as a fifth of the water used, Heins says. He traveled to Alberta and realized that he could modify the power plant technology to serve the oil sands industry. He invented a new SAGD evaporator that could purify and recover as much as 95 percent of the water used by in-situ oil recovery. “We spent almost four years working with the industry to show that there was a more economical, environmentally sound method of recovering the oil,” he says. “We saw a much simpler and cheaper way, which also allowed oil companies to recover and reuse virtually all of the produced water from their oil recovery process,” Heins says. He says that while there will always be some losses underground, the technology allows companies to use brackish water instead of fresh water.
Heins, who now works as general manager for thermal products at GE Water, says that the evaporators are not only effective but also efficient. They clean water by boiling off water from the contaminated feedstock and then condensing it as pure water vapor. It normally takes about 1,000 British thermal units (BTUs) to heat and boil one pound of water. But the evaporator’s unique design captures the heat generated during condensation and uses it to boil more water. As a result, the machine needs only about 25 BTUs per pound to do the work, a fraction of the norm.
Heins estimates that one evaporator can save 600 Olympic sized swimming pools of fresh water per year, or 500 million gallons. There are more than 20 GE evaporators in operation or under construction in Alberta today. “When people think of oil sand, they think of large surface mines,” he says. “Our water reuse technology is helping the industry continue its move toward the SAGD process, which leaves little imprint on the landscape.”