Air impingement system

Claim 1

An apparatus for drying a moving web comprising at least one air cap having a width corresponding to the width of the web to be dried, each air cap including at least one apertured plate, hollow support means for positioning the plate in relatively close proximity to the web, a high pressure plenum connected to said support means for delivering high pressure air through the apertures in said plate to impinge against said web, said support means having a throat of lesser cross-sectional area than said plate between said plate and said plenum, thereby providing an exhaust region of extended area behind each plate into which the impinging air streams are directed at a relatively low velocity and without an excessive pressure drop, the open area of the apertures in said plate constituting no more than about 3% of the area of said plate, the ratio of the distance of the apertures from the surface of the web to the diameter of the apertures being in accordance with the following table: Ratio of distance/ Open area diameter ______________________________________ up to 1% 3 - 6 greater than 1% up to 2% 2 - 5 greater than 2% up to 3% 2 - 4. ______________________________________

Claim 2

An apparatus for drying a moving web comprising at least one air cap having a width corresponding to the width of the web to be dried, each air cap including at least one apertured plate, hollow support means for positioning the plate in relatively close proximity to the web, a high pressure plenum connected to said support means for delivering high pressure air through the apertures in said plate to impinge against said web, said support means having a throat of lesser cross-sectional area than said plate between said plate and said plenum, thereby providing an exhaust region of extended area behind each plate into which the impinging air streams are directed at a relatively low velocity and without an excessive pressure drop, the open area of the apertures in said plate constituting no more than about 3% of the area of said plate, the ratio of the distance of the apertures from the surface of the web to the diameter of the apertures being in accordance with the following table: Ratio of distance/ Open area diameter ______________________________________ up to 1% 3 - 6 greater than 1% up to 2% 2 - 5 greater than 2% up to 3% 2 - 4. ______________________________________

Claim 5

An apparatus for drying a moving web comprising a high pressure plenum, a plurality of apertured plates extending across the width of the web to be dried, conduit means enclosing each of said plates and connecting the same to said plenum, each of said plates being spaced from adjoining plates along its entire periphery thereby providing exhaust channels for air streams impinging against said web, said conduit means having a cross-sectional area of lesser extent than the cross-sectional area of its associated plate inwardly of said plate in the direction of said plenum thereby providing an extended exhaust space between said plates and said plenum, and a common exhaust conduit communicating with said exhaust space, said conduit extending through and beyond said plenum, the open area of the apertures in said plate constituting no more than about 3% of the area of said plate, the ratio of the distance of the apertures from the surface of the web to the diameter of the apertures being in accordance with the following table: Ratio of distance/ Open area diameter ______________________________________ up to 1% 3 - 6 greater than 1% 2 - 5 up to 2% greater than 2% 2 - 4 up to 3%. ______________________________________

Claim 6

An apparatus for drying a moving web comprising a high pressure plenum, a plurality of apertured plates extending across the width of the web to be dried, conduit means enclosing each of said plates and connecting the same to said plenum, each of said plates being spaced from adjoining plates along its entire periphery thereby providing exhaust channels for air streams impinging against said web, said conduit means having a cross-sectional area of lesser extent than the cross-sectional area of its associated plate inwardly of said plate in the direction of said plenum thereby providing an extended exhaust space between said plates and said plenum, and a common exhaust conduit communicating with said exhaust space, said conduit extending through and beyond said plenum, the open area of the apertures in said plate constituting no more than about 3% of the area of said plate, the ratio of the distance of the apertures from the surface of the web to the diameter of the apertures being in accordance with the following table: Ratio of distance/ Open area diameter ______________________________________ up to 1% 3 - 6 greater than 1% 2 - 5 up to 2% greater than 2% 2 - 4 up to 3%. ______________________________________

Claim 9

An apparatus for drying a moving web comprising a high pressure plenum, a plurality of apertured plates extending across the width of the web to be dried, conduit means enclosing each of said plates and connecting the same to said plenum, each of said plates being spaced from adjoining plates along its entire periphery thereby providing exhaust channels for air streams impinging against said web so that air exhausting between the plates prevents cross flow interference of spent air with air streams, said conduit means having a cross-sectional area of lesser extent than the cross-sectional area of its associated plate inwardly of said plate in the direction of said plenum thereby providing an extended exhaust space between said plates and said plenum, and a common exhaust conduit communicating with said exhaust space, said conduit extending through and beyond said plenum.

Claim 10

An apparatus for drying a moving web comprising a high pressure plenum, a plurality of apertured plates extending across the width of the web to be dried, conduit means enclosing each of said plates and connecting the same to said plenum, each of said plates being spaced from adjoining plates along its entire periphery thereby providing exhaust channels for air streams impinging against said web so that air exhausting between the plates prevents cross flow interference of spent air with air streams, said conduit means having a cross-sectional area of lesser extent than the cross-sectional area of its associated plate inwardly of said plate in the direction of said plenum thereby providing an extended exhaust space between said plates and said plenum, and a common exhaust conduit communicating with said exhaust space, said conduit extending through and beyond said plenum.