Megtec Systems, Inc.

W. R. Grace Co.-conn.

W. R. Grace Co.

Durr Megtec, LLC

Michael O Rocheleau

Les Peterson

Steven J Zagar

Richard J Wimberger

Paul G Seidl

Randall D Helms

Kenneth J Moran

Donn DeNamur

David M Klein

Thomas Manning

Paul Seidl

Apparatus and methods particularly suited for drying tissue grade paper. In certain embodiments, a wet web, such as a web exiting a tissue manufacturing machine, is transferred to an air floatation dryer with specially arranged air bars and impingement nozzles described herein where the wet web is dried while still at least partly supported by an air-permeable belt. In certain embodiments, the specially arranged air floatation dryer comprises one or more air floatation dryer units through which the wet web is conveyed by way of a supporting endless loop or belt of air-permeable construction. The air bars and opposing impingement nozzles are so arranged as to force the web into contact with the belt and then subsequently lift the web from the belt surface in a repetitive and alternating fashion as the web and belt travel through the dryer.

Air bar arrangement for drying tissue on a belt

Infrared air float bar for use in floating and drying a continuous planar web of a material in a dryer. Direct radiated or reflected infrared electromagnetic energy from an infrared light source in a removable channel assembly accelerates drying, or evaporation of solvents, or curing of web material passing in proximity to the bar, either by infrared electromagnetic energy, or in combination with convention airflow. The infrared source is cooled by pressurized air passing through an interior portion of the removable air bar channel assembly, and the air is further conducted into fluid contact with the web in an air gap between the emitter and web to promote convective heat transfer and to contribute to the air pressure field supporting web flotation. The removable channel assembly is configured for replacement of the infrared emitter and to allow the setting of the pressurized cooling air flow to the optimum level.

Infrared float bar

Apparatus and method for the non-contact drying of a web of material. The apparatus includes air flotation nozzles for floating the web, and direct air impingement nozzles for enhanced drying of the web. The nozzle arrangement is particularly well-suited to float and dry light weight webs under moderate to high tension. Increased cushion pressure is created to support the web preferably with the same horsepower as conventional arrangements. The increased cushion pressure pad of the nozzle arrangement allows for good flotation with reduced velocities below about 11,500 FPM. Machine direction wrinkles are removed and the result is positive flotation with no marking on the web or ink build up on the air bars. The nozzle arrangement includes pairs of flotation nozzles directly opposing pairs of direct impingement nozzles. A perforated member can be positioned between flotation nozzles within a pair of flotation nozzles to control return air.

Paired air bar/hole bar arrangement in web dryer

Web stabilizer particularly for one-sided flotation of a running web. The device includes two discharge slots which allow for increased draw down force, which flattens machine direction wrinkles in a floating web. There is a primary discharge slot and a second discharge slot spaced from and stepped down from the primary discharge slot, a first web support surface between the primary discharge slot and the secondary discharge slot, and a second web support surface downstream of the secondary discharge slot in the direction of web travel. An integral blower provides a supply of air that is uniformly distributed to the primary and secondary slots. Air discharged from the primary slot is gathered into the air stream of the secondary slot and creates an increased air cushion to provide greater support to the web and thereby remove machine direction web wrinkles caused by higher tension in light weight webs.

Step air foil web stabilizer

Step air foil particularly for one-sided flotation of a running web, and web dryer incorporating the same. The air foil includes two discharge slots which allow for increased draw down force, which flattens machine direction wrinkles in a floating web. The air foil includes a primary discharge slot and a second discharge slot spaced from and stepped down from the primary discharge slot, a first web support surface between the primary discharge slot and the secondary discharge slot, and a second web support surface downstream of the secondary discharge slot in the direction of web travel. The air foil is in communication with an air supply which provides a supply of air that is uniformly distributed to the primary and secondary slots. Air discharged from the primary slot is gathered into the air stream of the secondary slot and creates an increased air cushion to provide greater support to the moving web and thereby remove machine direction web wrinkles caused by higher tension in light weight webs.

Step air foil

Air turn for supporting and optionally drying a web, comprising an arcuate surface having a plurality of apertures formed therein. Pressurized gas is supplied to the air turn plenum, and exits through the plurality of apertures to form a cushion of air to float the web. Turn angles of about 90&deg; to about 300&deg; with no contact to the web are achievable with the apparatus of the present invention. The unique semi-circular design allows for non-contact flotation and turning of a tensioned web with low pressure requirements, reduced air spillage and reduced noise level. Multi-chamber turns can be used with each section having independently controlled pressurized gas.

Non-contact floating device for turning a floating web

Drying apparatus including pressure control of air supply feeding an air bar and subsequently impinging upon a web, so as to avoid or compensate for web shift without disturbing the cushion pressure and flotation techniques necessary for adequate web flotation and drying, as well as a method of regulating the pressure of supply air to such air bars. A damper or valve is positioned in the header system between first and second ducts feeding each air bar. Proper adjustment of the damper regulates the pressure of supply air in each duct, and compensates for web shift or minimizes or prevents web shift from occurring.

Non-contact flotation web guide/dryer

Infrared air float bar for use in floating and drying a continuous planar web of a material in a dryer. Direct radiated or reflected infrared electromagnetic energy from an infrared bulb in a removable air bar channel assembly accelerates drying, or evaporation of solvents, or curing of planar web material passing in proximity to the infrared air float bar either by infrared electromagnetic energy, or in combination with Coanda air flow. The infrared bulb is cooled by pressurized air passing through an interior portion of the removable air bar channel.

Infrared air float bar

A web dryer for upper and lower stretches of horizontally extending lengthwise moving web, having stacked air bar assemblies of the compact type, has a single burner for supplying hot gases to the two air bar assemblies that are between the stretches. The burner projects into an inlet section of a T-shaped duct, which has branches terminating at a pair of outlets, each opening to, but spaced from, the air inlet of the blower for one of said two assemblies. A deflector plate in the inlet section of the T-shaped duct, swingable about an upright axis at the downstream end of that section, apportions burner combustion products between the branches. The burner is controlled by a thermostat in the header of the lower of said two assemblies, the deflector plate by a thermostat in the header of the upper of said two assemblies.

Compact dryer for two web stretches

An assembly of air bars from which air is blown against a lengthwise moving web to contactlessly confine it to a plane comprises a header having a ported wall extending along its full length, parallel to said plane. Each of a series of outlet ports along the ported wall opens into an air bar intermediate its ends. A centrifugal blower has its cylindrical rotor near a rear end of the header, spaced to the side of said ported wall remote from the plane. An internal plenum chamber in the header opens to the outlet ports in the rear one-third to one-half of the header. The blower has one outlet near the rotor periphery from which air flows into the front part of the header and another outlet, spaced at a greater distance from the rotor periphery, from which air flows into said plenum chamber. The header is movable toward and from said plane relative to the blower, for air bar retraction to facilitate web threading.

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Sobieski, WI, United States of America

Michael O Rocheleau