June/July 2008

Engineering Exchange

Improving bitumen recovery

By H. Weldon


A K40 nuclear online analyzer measures potassium levels in an oil sands hydro-transport slurry line.

The Sensors Engineering Business Unit (SENG), part of the Engineered Products and Services team at the Alberta Research Council, focuses on the development of sensors for measurement and analysis, a small but highly specialized field of engineering.

In 2000 SENG, headed by Rodney Ridley, its manager, teamed up with Syncrude, with the aim of improving bitumen recovery. Syncrude was concerned that the bitumen extraction process was not as efficient or effective as it could be. Significant losses of bitumen ended up in the tailings pond even under the best circumstances, and Syncrude was determined to find a way to ensure that the most bitumen possible was extracted during processing — less in the pond and more in the barrel, so to speak.

Working closely with Syncrude researchers, the ARC team looked at all stages of the processing operation, to see where improvements could be made.

Step 1: Conveyor belt

A Near InfraRed oil sands analyzer was developed and adapted to give a bitumen percentage measurement prior to processing. This full scanning instrument utilizes short wave infrared reflectance to “read” the bitumen content in the mined material, enabling downstream process inputs such as chemicals and water to be adjusted according to the quality of raw material detected upstream.

Step 2: Hydrotransport pipeline

Clay is a sticky material that is endemic in the oil sands. Sometimes there’s more, sometimes less, but it can really disrupt efficient bitumen extraction. Fortunately, clay contains potassium and emits miniscule amounts of gamma radiation. This particular radioactive isotope (K40) is readily detected by ARC’s K40 gamma spectrometer analyzer. This instrument provides timely information on clay fines and allows process operations to quickly make adjustments to compensate for changes in the clay fines content.

Step 3: Froth/middlings interface vision system

This system gives the operator real-time measurement of the interface between the middlings and froth in the primary separation vessels. Previously, the level measurement was corrected manually by observing the fluids through a glass window. The new real-time vision system automatically determines the interface level and digitizes a video signal, which is then processed using algorithms to produce the level measurement, thus removing human error.

Step 4: Online tailings analyzer

This system measures the bitumen levels in the tailings prior to being released to the ponds. The data captured allows for process improvements and modifications at the primary separation vessels and froth treatment plants to further reduce bitumen loss. Basically, it measures the end result so that tweaking can be done at an earlier stage to counter the loss of bitumen.

Other oil sands companies have shown interest in this technology: CNRL is installing both the infrared and K40 systems at their site; Albian is looking to retrofit; and Suncor is assessing their processing plant for the possibility of utilizing some, or all, of the ARC/Syncrude-developed sensor systems.

One of the challenges of designing delicate sensors and precise measuring instrumentation for use in the oil sands is the environment itself. “The oil sands are abrasive and sticky,” Ridley pointed out, “and the temperatures can range from minus 40 degrees to up to 50 degrees. The trick is building something that will survive those conditions.”

SENG works primarily with the oil sands and pulp and paper industries but has recently branched out to hard rock mining. Through ARC this team is able to focus entirely on its area of expertise: something that would not be feasible on their own because of the limited market. All members of ARC’s Engineered Products and Services team enjoy diverse work experiences where every day brings new projects and unique challenges.

Post a comment


PDF Version