Method in drying of paper
AssigneeAndritz Technology and Asset Management GmbH
InventorsAnders Andrén, Stefan Backa, Johan Ekh, Xiaolong Feng, Thomas Liljenberg, Ulf Persson, Xiaojing Zhang
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Abstract
A method in consolidation and drying of paper. A wet web is contacted with superheated steam, whose temperature is 200-600° C. for the purpose of reducing, by heat transfer from the superheated stream, the water content of the web by evaporation of a substantial part of the water in the same. The wet web is supported and transported by means of a heat-conductive, gas-impermeable belt whose width is equal to or exceeds the width of the web, and jets of the superheated steam are directed towards the side of the web facing away from the belt.
Claims35
A method in consolidation and drying of paper, a wet web being contacted with superheated steam, at the temperature of 200-600° C., for the purpose of reducing, by heat transfer from the superheated steam, the water content of the web by evaporating a substantial part of the water in the same, comprising
- supporting and transporting the wet web by means of a heat-conductive, gas-impermeable belt whose width is equal to or exceeds the width of the web, and
- directing jets of the superheated steam towards the side of the web facing away from the belt;
- wherein the drying occurs in at least two steps with different temperature of the superheated steam.
A method in consolidation and drying of paper, a wet web being contacted with superheated steam, at the temperature of 200-600° C., for the purpose of reducing, by heat transfer from the superheated steam, the water content of the web by evaporating a substantial part of the water in the same, comprising
- supporting and transporting the wet web by means of a heat-conductive, gas-impermeable belt whose width is equal to or exceeds the width of the web, and
- directing jets of the superheated steam towards the side of the web facing away from the belt,
- wherein the drying is preceded by a preheating step in which the web is contacted with, or heated indirectly with, essentially saturated water vapour, and
- wherein the web is preheated to a temperature between 90 and 100° C.
A method in consolidation and drying of paper, a wet web being contacted with superheated steam, at the temperature of 200-600° C., for the purpose of reducing, by heat transfer from the superheated steam, the water content of the web by evaporating a substantial part of the water in the same, comprising
- supporting and transporting the wet web by means of a heat-conductive, gas-impermeable belt whose width is equal to or exceeds the width of the web,
- directing jets of the superheated steam towards the side of the web facing away from the belt, and
- blowing, in a second drying step, steam having a temperature between 300 and 400° C. and a speed exceeding 50 m/s, preferably having a temperature between 330 and 370° C. and a speed between 60 and 120 m/s,
- wherein the drying is preceded by a preheating step in which the web is contacted with, or heated indirectly with, essentially saturated water vapour.
Dependencies are inferred from the claim text.