Mechanical Pulp Production Research Articles

機械パルプの光退色抑制について

Production of mechanical pulps (MP) have been increased for useful utilization of woods. However, MP have two main problems on use of it. One is hard-bleachability and the other is light-induced color reversion. On hard-bleachability, MP having higher brightness can be produced by improvement of bleaching methods and development of pulping processes. But the problem of the color reversion has not solved yet, though many works on prevention of the color reversion have been conducted.This paper describes about the prevention of light-induced color reversion of mechanical pulps. And furthermore, a mechanism of the color reversion, change of lignin caused by pulping process and effect of the change on the color reversion, and effect of bleaching of MP on the color reversion are also described.

PQM Technology and its Application in Pulp and Stock Process Control

The PQM technology was firstly tried in mechanical pulping processes, where the results with the optical measuring methods (developed by STFI) were confirmed suitable for use in an industrial environmentNow PQM:s are installed along the production line from mechanical pulp production on grinders and refiners through screen room and reject refining to paper machine stock and white water. The PQM technology is not just limited to mechanical pulp production, it is suitable whenever mechanical treatment of pulp takes placeThe PQM signals are fed back to a hierarchic control system where the base level, machine control, provides stable operation of the machinery, e.g. grinder, refiner etc. Next level involves the PQM in a straight line feedback approach. However, when controlling several production units, a distributed quality feedback appliesAll PQM measurements, freeness, fiber fractions and shives are made on the same primary pulp sample. Thus no sampling errors exist within this “two or three dimensional” test performed and accurate control actions are promotedTo benefit from the PQM, an integration with an ASEA Master Process Control System that performs the necessary control functions pays off. Increased stock quality and energy savings are demonstrated results