Nozzle arrangement in airborne web-drying and method for improving heat transfer in airborne web-drying

摘要

A nozzle arrangement in an airborne web-drying apparatus for drying a coated paper web (10) or the like. The nozzle arrangement comprises at least one overpressure nozzle (14), which is arranged to blow drying air both in the web's travel direction and against the web's travel direction. The nozzle arrangement comprises further a direct impingement nozzle (16) combined with the exit side and/or the entrance side (26) of the overpressure nozzle, in which direct impingement nozzle a plurality of nozzle slots or nozzle orifices (17) are formed in order to blow drying air mainly perpendicularly toward the web. The perpendicular distance (a₁) from the nozzle surface (30) of the direct impingement nozzle (16) to the web is larger than the perpendicular distance (a₂) from the supporting surface (32) of the overpressure nozzle (14) to the web.