Researchers at The University of British Columbia (UBC) have helped engineer a new pulp screening technology that is up to 50 percent more energy efficient and is saving Canada’s pulp and paper industry approximately $20 million a year.

The pulp and paper sector is one of Canada’s largest manufacturing and export industries. In British Columbia alone, it provides more than $4 billion in economic benefits, including more than 30,000 jobs. It’s also a major energy user, consuming nearly 20 percent of all of the electricity produced in the province.

Pulp screening, part of the process that breaks wood chips down into pulp, is an essential part of manufacturing pulp and paper products, but it is energy intensive. To produce pulp, tree fibers immersed in water are pushed through a vertical screen, much like a juicer would push fruit pulp through a filter.

To prevent the screen from clogging, a rotor spins across its surface more than 20 meters per second creating a negative pressure on top of the blades that keeps the screen clear. Most B.C. mills have 10 to 50 rotors, each continuously driven by 200-horse-power motors.

Aikawa Fiber Technologies (AFT), a Sherbrooke, Que., company and one of only a few manufacturers of pulp screens in the world, recognized the potential to improve the hydrodynamics of these rotors to be more energy efficient.

They collaborated with UBC’s James Olson, a member of the  Advanced Papermaking Initiative (API) at the university's Pulp and Paper Centre to come up with a better design.  The result is a rotor shaped like an airplane wing.

The improved rotor efficiently unclogs pulp screens but runs at a slower speed than conventional rotors, reducing the power needed by 50 percent. Olson’s team provided the screen testing equipment to validate the rotor’s effectiveness. Pulp and paper mills across the province replaced all of their aging rotors with AFT's new ones in 2005, which, province-wide, saves enough energy a year to power 15,000 homes. An additional 100 rotors were installed in 30 more mills across Canada.

Anh Tuan