Method of and apparatus for removing liquid for webs of porous material

Abstract

An apparatus for removing water or other liquids from webs of such porous materials as fibrous paper webs coursing through a papermaking machine without substantially compacting the webs. The web which may be coherent or perforate passes over a sector of a cylinder having preferential-capillary-size pores through its cylindrical-shape porous cover. Preferably, the porous cover comprises hydrophilic material which is substantially non-resilient and which renders the surfaces of the porous cover wettable by the liquid of interest. A portion of the interior of the cylinder may be subjected to a controlled level of vacuum to effect pneumatically augmented capillary flow of liquid from the web; and another portion of the cylinder may be subjected to pneumatic pressure for expelling the transferred liquid outwardly through a portion of the porous cover which is not in contact with the web. The method may comprise controlling the level of vacuum as a function of air flow to maximize liquid removal from a web while substantially obviating air flow through the capillary-size pores of the porous cover of the cylinder. Preferential-capillary-size pores are such that, relative to the pores of a wet porous web, normal capillary flow would preferentially occur from the pores of the web into the preferential-capillary-size pores of the porous cover when the web and porous cover are juxtaposed in surface-to-surface contact.

Dependencies are inferred from the claim text.