Patent ID: 8444824

Claim:
A method of enhancing runnability in a paper or board machine, comprising the steps of: drying a paper web in a dryer section of the paper or board machine in at least one drying group which employs single-wire draw in which a paper web is dried on a first heated cylinder surface of a first drying cylinder supported by a drying wire that presses the web onto the first heated cylinder surface; traversing the web from the first drying cylinder on an outside surface of the drying wire to a cylindrical surface of a reversing roll along a transfer length of 80-400 mm along a common tangent, so the drying wire engages said cylindrical surface overlain by the paper web, and further transferring the web from the reversing roll to a second heated cylinder surface of a second drying cylinder supported by the drying wire which presses the web onto the second heated cylinder surface; wherein the first drying cylinder, the second drying cylinder and the reversing roll positioned between the first drying cylinder and the second drying cylinder, form together with the drying wire a pocket space therebetween; enhancing the runnability of the web by using a runnability component placed in the pocket space, to produce a selected negative pressure of at least 1000 Pa in an area which is applied substantially uniformly along the entire transfer length to the web as the web transfers between the first drying cylinder to the reversing cylinder and confining the area of the negative pressure between the first drying cylinder and the reversing roll with a first mechanical seal mounted to the runnability component and positioned against the first heated cylinder surface of the first drying cylinder and a second mechanical seal mounted to the runnability component and positioned against a portion of the cylindrical surface of the reversing cylinder not wrapped by the drying wire; wherein the step of traversing the web from the first drying cylinder on an outside surface of the drying wire to a cylindrical surface of a reversing roll begins at an opening gap, opening away from the first drying cylinder where the web leaves the first drying cylinder, and wherein the mechanical seal positioned against the first heated cylinder surface of the first drying cylinder is spaced from the opening gap along the first heated drying cylinder surface such that at the selected negative pressure the opening gap does not open to such an extent that the drying wire is pressed against the mechanical seal positioned against the first heated cylinder surface of the first drying cylinder.