Dewatering press assembly for a papermaking process has an air-tight hood that is pressurised or evacuated

摘要

In a papermaking process a fibrous web is formed between two sieve belts as it runs between a first nip point between an outer roller (9) and an inner roller (6), proceeding around the inner drum to a second nip point between the inner drum and a second outer roller (14). The arc over the sieve between the two outer drums is covered by a hood (15). The hood forms an air-tight unit embracing one joint aspect of the rollers and rum. The void between the hood, sieve surface, rollers and drum may be pressurised or evacuated. The pressure or vacuum is adjustable and acts on the inner face (5.1) of the outer sieve (5). The hood exerts variable pressure on the full width of the outer sieve (5) via rigid link pieces (17).