A successful cooperation between Canada-based FPInnovations and Canfor, along with Sweden-based PulpEye, has resulted in the world’s first technology for measurement of fiber wall thickness. As the first pulp producer in the world, Canfor has installed the fiber wall thickness module, FWT, in four PulpEye units in its pulp mills.

 

FPInnovations has patented a technology for determining fiber wall thickness and fibril angle of individual fibers. The rapid and robust technology is based on an innovative light system for colorimetric based quantification of the desired properties. PulpEye has the worldwide rights and is now commercializing the technology as an add-on technology for the industry-leading PulpEye online pulp and fiber analyzer system.

Fiber wall thickness is an important parameter as it influences the strength properties of the pulp, but so far it has not been possible to measure it online. There can be a number of reasons to measure fiber wall thickness online. It is an efficient method for raw material control to make sure that the mix of e.g. saw mill chips, roundwood from thinnings, different species, etc., is done so that a consistent pulp quality is maintained. The FWT module can control the efficiency of a fiber fractioning process. By measuring fiber wall thickness, it is possible to calculate strength data and suggest level of refining to pulp customers, helping them achieve the requested paper and board strength properties.

 

The FWT module is based on optical measurement of a continuous fibre stream of a controlled concentration passing the patented module. Cellulose is an anisotropic material and hence polarizes light in two wave planes perpendicular to each other and with different refractive indices. In the FWT module, LED light of specific wavelengths is sent through the fiber stream and the resulting light is picked up by a color camera. The result is an image where the fibers are visualized and wall thickness is shown in different colors.

 

"This Swedish-Canadian cooperation is a good example of bringing the best from each partner to develop a ground breaking technology," said Öjvind Sundvall, MD PulpEye. "Ho Fan Jang at FPInnovations has developed and patented this technology. PulpEye has the equipment where the FWT module is perfectly integrated and Canfor Pulp took part in the development with their pulp knowledge and made the first mill installations."

"Fiber wall thickness is a fundamental kraft pulp quality attribute," said Paul Watson, director of research and innovation, Canfor Pulp. "Having now developed a routine and robust online measurement for our PulpEye, FWT information delivered to Canfor customers should assist their product development and optimization initiatives. This has been an extremely positive collaboration which has defeated a very challenging and longstanding technical issue." 

Photos below show that in the FWT module (top photo)  LED light of specific wavelengths is sent through the fiber stream and the resulting light is picked up by a color camera. In the bottom photo, the measurement result is an image where the fibers are visualized and wall thickness is shown in different colors.