New sensor may lead to energy savings

by Maria Lironi

Peter Wild joined UVic's mechanical engineering department in 2003, but is no stranger to this campus - he earned his PhD here in 1994. Wild's main research focus is renewable energy. Along with colleagues in UVic's institute for integrated energy systems, he's working on an experimental computer system that will be used to study how to integrate renewable energy into real-world applications. In a related project, he's developing an energy plan for a remote northern community. He finds this work particularly rewarding as "remote communities offer one of the most promising applications for renewable energy."

Mechanical engineering professor Dr. Peter Wild's newest invention is small enough to sit in the palm of your hand, yet it has the potential to make the pulp and paper industry more efficient.

His device - known as a force sensor - could lower costs for the pulping stage of the paper-making process and allow the industry to become more competitive.
There are two main pulping techniques: chemical pulping and mechanical pulping. It's the latter that interests Wild.

Modern mechanical pulping mashes the wood chips between rotating metal disks to produce pulp. While this refining method provides a higher yield than chemical pulping, the resulting paper quality is lower. That's because the energy-intensive grinding method breaks many of the wood's fibres.

As a result, the paper has a weaker fibre network and a high lignin content, which causes it to yellow when exposed to sunlight. Paper produced by this process is used mainly for newsprint, telephone books and other applications where high-quality paper is not really needed.

Wild, along with Daniel Ouellet at the Pulp and Paper Research Institute of Canada (PAPRICAN) and Marc Sabourin of Andritz Ltd. (an international technology group that makes advanced production systems for the pulp and paper industry), has spent the last five years developing a force sensor that can be embedded in the metal disks.

"The sensor measures the force being applied to the wood chips and pulp by the rotating metal disks," says Wild. "In this way, the refining process can be controlled to give a desired quality of pulp."

The sensor will undergo trials at a B.C. mill in 2005. If successful, the sensor could significantly lower the amount of energy required for the pulping process.
The project is funded by the Mechanical Wood-Pulps Network (one of 21 national Networks of Centres of Excellence), PAPRICAN, Andritz and the Natural Sciences and Engineering Research Council.