Louvered steam box for controlling moisture profile of a fibrous web

Claim 1

A steam hood for use adjacent to a moving moist fibrous web to control the moisture profile across the width of the web which comprises: a. a steam plenum means of sufficient length to extend across the web; b. a steam inlet means for the plenum means, said inlet means being adapted to supply substantially nonturbulent steam at essentially atmospheric pressure within the plenum means; c. a steam outlet control means at the outlet of the plenum means so as to be positionable adjacent to the web at the outlet of the steam hood, said control means structured to deliver varying amounts of steam from the plenum means to the web at different positions across the full width of the web, said plenum means permitting free lateral movement of steam to said different positions, said control means further comprising a plurality of side-by-side adjoining compartments across the width of the control means, each compartment being of essentially rectangular cross section defined by side and end walls, each compartment being in communication with the plenum means; a damper means located in each compartment, said damper means comprising at least one damper blade affixed to a shaft journaled in the compartment walls and a position control lever affixed to the shaft so that the damper blade is rotatable between a closed and an open position to act as a steam outlet valve for the compartment; and operating rod means associated with each position control lever in order to individually control the position of each damper blade, each operating rod means extending to an operating location on the steam hood wherein each damper means can be individually positioned to deliver an amount of steam to an adjacent portion of the web so as to achieve a more uniform moisture profile across the web.