First Mill Scale Experiences of the Water Jet Pulpstone Conditioning System at UPM-Kymmene Voikkaa and Rauma Paper Mill, 1997 Pulping Conference Proceedings

In the optimization of groundwood pulp quality, maintaining the pulpstone at a constant sharpness has been a major problem. As an alternative to metallic sharpening burrs, Water Jet stone conditioning offers a new approach to this problem.

In the Water Jet conditioning system, a jet of high pressure water, up to 2500 bar, is aimed at the stone surface. The advantage of this method, which keeps the stone clean and maintains its porosity, is that the force of the treatment can be adjusted accurately by controlling the jet pressure and the number of treatment cycles. This greatly improves the repeatability of stone conditioning.

The result is easier grinder control and a substantial decrease in the variation of the freeness and quality of pit pulp. This, in turn, enhances the controllability of the screening room and ultimately produces more uniform pulp quality.

This paper presents the first mill-scale experiences with Water Jet conditioning. The first section of the findings focuses on the grinder controls at the Voikkaa Paper Mill. The effect of Water Jet conditioning on the pulp quality and screening room control at the Rauma Paper Mill is discussed in the second section of the results.

Briefly, the results can be summarized as follows. The variation in grinder control decreased in all the main control categories, and grinder production increased. Pulp quality improved, and there was a corresponding decrease in the variation in groundwood pulp quality.