An apparatus and method for conditioning a moving porous web on a
papermaking machine is disclosed. The web has a first and a second
surface and a high temperature gaseous boundary layer adjacent at least
the second surface. The apparatus contains means for conveying the first
surface of the porous web adjacent a support surface in a direction of
travel, means for applying a cooling gas against the second surface of
the web in a direction substantially normal to the second surface of the
web to exert a gas pressure adjacent the second surface, means for
stripping at least a portion of the boundary layer away from the second
surface of the web prior to contacting the web with the cooling gas, and
means for exerting a vacuum force adjacent the first surface of the web
associated with the support means and substantially opposite the location
at which the pressure force is exerted adjacent the second surface of the
web in order to promote, by a combination of the pressure and vacuum
forces, a flow of gas through the web from the second surface to the
first surface. The apparatus may also include means for moisturizing the
web subsequent to cooling the web. The apparatus and method provide a
novel combination of stripping and gas pressure/vacuum force effects for
more rapid and efficient removal of the boundary layer at the speeds of
modern papermaking machines to improve the condition of the web for
further on-line treatments, such as calendaring.