Steam box for a papermachine

The steam box (1) serves for controllable steaming of a paper web in zones. It is arranged transversely to the paper web (2) over the entire width thereof and has adjacent pressure chambers (3) expediently sized corresponding to defined zones. These chambers are connected to a steam line (4) of a steam tract and serve to distribute the stream of steam in the direction of the paper web (2). To prevent deflection of the steam from the zone which is to be heated into an adjacent zone which is not to be heated, the steam box is equipped with an air tract, provided parallel to the steam tract, with an air line (5). This air tract is designed for controllable guiding of an air stream into the zones in the direction of the paper web (2). While a zone is treated with steam, an adjacent zone is treated with air. Due to the air pressure in this zone, the deflection of the steam from the zone which is being treated with steam and is to be heated, into the adjacent zone is prevented. In addition, a zone can be cooled by treatment with the air. As a result, this zone is drained to a lesser extent and any prior overdrying of such zones can thereby be corrected.