Sonic drying of webs

Claim 1

Web drying apparatus having a passage for an endless web therethrough for controlled diminution of liquid within the surface of an elongated permeable web, having web positioning means to laterally locate a said web relative to the longitudinal edges thereof on passage through said apparatus, a plurality of sound generating whistle means on one side of a path of travel of said web in mutual spaced relation arranged to provide a sound field having a plurality of sequential high intensity zones, spaced along the web path of travel, and to propagate longitudinal sound waves in a direction substantially normal to the web, first gaseous fluid supply means connected to said sound generating means in energizing relation therewith to generate in operation said longitudinal sound waves, second gaseous fluid supply means having outlets intermediately of at least some of said zones to provide a wiping gaseous flow in a direction substantially normal to the plane of the web, plural housing means extending transversely of said web path respectively located adjacent at least some of said high intensity sound zones to provide a plurality of gaseous fluid return flow paths extending away from said web path, to receive said wiping gaseous flow having liquid and vapor entrained therewith, and recirculation means to recirculate a selected portion of return gaseous flow to the web, to provide control of web drying conditions.