Drying cylinder

A papermaking machine producing a fibrous web, the papermaking machine comprising:

• a drying cylinder including:
• a load bearing element;
• and
• an outer cover layer heated by a hot fluid, between said load bearing element and said outer cover layer there is at least one cavity through which the hot fluid flows in direct contact with said outer cover layer, at least a portion of said outer cover layer being so thin that a ratio of the thermal conductivity of the material and a thickness of said outer cover layer is greater than a limiting value, which is 3.2 kW/m2K for steel, 30 kW/m2K for aluminum, 18 kW/m2K for bronze alloys, 3.4 kW/m2K for copper and 6.1 kW/m2K for magnesium;
• at least one water-absorbent belt, said water-absorbent belt along with the fibrous web wrapping about a portion of said drying cylinder, the fibrous web being in contact with said drying cylinder;
• and
• a dense belt overlying said at least one water-absorbent belt about said portion of said drying cylinder, at least one portion of said dense belt being cooled.

A papermaking machine producing a fibrous web, the papermaking machine comprising:

• a drying cylinder including:
• a load bearing element;
• and
• an outer cover layer directly heated by a hot fluid, between said load bearing element and said outer cover layer there is at least one cavity through which the hot fluid flows, at least a portion of said outer cover layer being so thin that a ratio of the thermal conductivity of the material and a thickness of said outer cover layer is greater than a limiting value, which is 3.2 kW/m2K for steel, 30 kW/m2K for aluminum, 18 kW/m2K for bronze alloys, 3.4 kW/m2K for copper and 6.1 kW/m2K for magnesium;
• and
• a belt along with the fibrous web wrapping about a portion of said drying cylinder, the fibrous web being in contact with said drying cylinder, said belt having a tension of at least 10 kN/m.