A paper drying apparatus and method therefor including an infrared drying unit and a vacuum unit, wherein the infrared drying unit emits infrared radiation in a direction toward the vacuum unit. A fabric sheet for carrying a paper web is provided, wherein the fabric sheet passes between the infrared drying unit and the vacuum unit. The infrared drying unit is positioned on the side of the fabric sheet adjacent to the paper web and the vacuum unit is juxtaposed on the opposite side of the fabric sheet from the infrared drying unit, wherein the vacuum unit draws air through the paper web in a direction from the infrared drying unit toward the vacuum unit. The combination of the infrared drying unit with the vacuum units provides a compact arrangement which efficiently removes moisture from the paper web. After passing by the infrared drying unit, the fabric sheet then conveys the paper web toward a final drying drum where the paper web is transferred from the fabric sheet to the final drying drum through the use of a pressure roll.

The invention concerns an arrangement for lowering the noise level in connection with the cooling layer (12) in a pulp dryer (10). The heat-insulated bottom wall and top wall of the cooling layer (12) are accomplished by means of a sound-attenuating construction (21,22), and the wall at the inlet side of the cooling layer (12) is also accomplished by means of a sound-attenuating construction (23). At the outlet side of the air flow from the cooling layer (12) in a pulp dryer (10), sound-attenuation baffles (26) are provided, which are preferably perpendicular or inclined in relation to the direction of the air flow and which are placed at a distance from one another.

An apparatus and method for drying a wet sheet material such as a paper web is presented. The apparatus is provided with a suitable number of dryer cylinders operating in conjunction with a plurality of steam blast ports disposed adjacent to the dryer cylinders. A vertically movable canopy hood and a middle hood having sheet entry/exit opening and a door opening device are provided. The wet sheet material is held between two endless fabric belt, and passed through the dryer cylinders alternatively by means of suction fabric rolls, fabric rolls and fabric tension rolls. The drying process is carried out in an atmosphere of superheated steam of over 100°C inside the canopy hood and the middle hood, and the steam generated from the wet sheets is recirculated through an exhaust screen, a super heated steam circulating fan, an adiabatic compressor and a supply duct. Another atmosphere of heated moist air having a dew point of at least 80°C is also employed. The dried paper product manufactured has high dimensional stability and exhibits superior printing characteristics and substantially increased paper strength, and the process is highly energy conserving.

It is a known phenomenon that the web during the drying moment in a paper machine shrinks. The shrinkage in the machine direction can be controlled by arranging the different driving groups in the drying section to operate at different speeds. The shrinkage in cross direction, however, heretofore was not brought under control. The present invention has the object to solve thos problem.

According to the invention, the problem of shrinkage is solved in that the web during a certain drying interval is subjected to outward directed forces, which are applied during a suitable drying interval and preferably at a low dry content, for example directly after the press section.

A process for manufacturing of kraft paper, especially kraft sack paper, on a multi-wire machine in which the web is dried by a combined cylinder drying and free drying and is optionally creped or micro-creped and optionally also glazed. By forming the web into two or more layers which are couched together in the wire part of the machine and subsequent shrinkage in order to obtain a stretch at break of at least 2.5% in the machine direction and of at least 5% in the cross direction, improved strength properties are provided.

A process for manufacturing of kraft paper, especially kraft sack paper, on a multi-wire machine in which the web is dried by a combined cylinder drying and free drying and is optionally creped or micro-creped and optionally also glazed. By forming the web into two or more layers which are couched together in the wire part of the machine and subsequent shrinkage in order to obtain a stretch at break of at least 2.5% in the machine direction and of at least 5% in the cross direction, improved strength properties are provided.

A drying system and method for removing volatile liquid from a liquid bearing web of material by evaporation includes means for moving the liquid bearing web (10) of material through a drying station (12) and heating means (14) position at the drying station, for applying evaporation energy to the liquid bearing web (10) of material to effect evaporation of the volatile liquid from the web. Electrostatic means (30) is provided for subjecting the web of material to a static electrical field at the drying station (12), whereby the evaporation of volatile liquid from the web is enhanced. Evaporation energy may be applied to the liquid bearing web (10) by bringing a heated surface (14) in contact with the web or by irradiating the web with infrared energy. Alternatively, evaporation energy may be applied to the liquid bearing web (10) by directing heated air against the web.

Zur optimalen Vergleichmässigung des Feuchteprofils wird die Papierbahn zunächst mit konventioneller Zylindertrocknung (3) auf eine Feuchte von 10-20% getrocknet. Anschliessend wird eine kapazitive Hochfrequenztrocknung (4) auf etwa 6-10% Feuchte vorgenommen. Die Trocknung auf die gewünschte Endfeuchte von z.B. 4%wird dann wieder mit einem Zylindertrockner (5) durchgeführt. Die Einsatzgrenzen des Hochfrequenztrockners sind dabei u.a. durch die Kosten für HF-Energie und die Überschlagsgefahr gegeben.