DUAL-SCREEN FORMER AND METHOD

摘要

Dual-screen former and method for producing a fibrous material web from a fibrous material suspension. The dual-screen former includes screen belts having an endless loop lower screen and an endless loop upper screen. The screen belts are adapted to form a dual-screen zone having an initial region that is oriented bet ween substantially horizontally and approximately 20.degree. from substantially horiz ontally, and the dual-screen zone includes the initial region and an end region. A forming su ction roll is located within the endless loop upper screen, and the screen belts are g uided over a portion of the forming suction roll. A plurality of pressing elements are located within the dual-screen zone and are adapted to be elastically pressed against on e of the screen belts. A second suction roll is located within the endless loop of th e upper screen and a third suction roll located within the endless loop of the lower scr een, such that the end region of the screen belts is guided over the second and third suction rolls. The endless loop upper screen is lifted off the fibrous material web at t he third suction roll. The method includes directing a fibrous pulp suspension into the dual-screen zone, removing fluid from the fibrous pulp suspension through the lo wer screen loop at the forming suction roll, suctioning further fluid from the fibro us pulp suspension through the upper screen loop via the forming suction roll, and press ing the pressing elements against the adjacent one of the upper and lower screen loo p so that they produce pressure pulsations in the pulp suspension.