The rebuild of both screw presses(#21 and #22) included installation of a new Low-Energy Screw Shaft (LESS) as well as split grooved baskets for the medium-pressure zone in order to widen the operating window of the presses and allow higher production rates. The design of the LESS enables a new compression curve, resulting in a higher throughput at the same installed power.
The screw press upgradesare part of the step-by-step optimization of the BCTMP (bleached chemi-thermomechanical pulp) process that is currently in progress, with the overall aim of improving the availability of the plant.Press #21 is used as a wash press, and press #22 acts as a secondary stage in the washing process.
Metsä Board is a leading European producer of premium fresh fiber paperboards, including folding boxboards, food service boards, and white kraftliners. The company is part of Metsä Group, a Finnish forest industry group that operates in some 30 countries. TheJoutseno mill produces BCTMP for Metsä Board’s own board mills and has a production capacity of 320,000 t/a.