Method for controlling curl of paper in a dryer section of a paper machine
AssigneeValmet Corporation
InventorsVesa Ijas, Kari Juppi, Pasi Ahonen, Jaakko Kallioniemi
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Abstract
A method in a dryer section of a paper or board machine for controlling curl of paper, in which steam treatment and/or moistening of the paper web is/are employed. The operations carried out in order to control the curl of the paper web are carried out in a number of stages when the web temperature is, during at least one stage, lower than 85.degree. C., preferably lower than 75.degree. C., and when the dry solids content of the web is in the range of K1-K2, wherein K1 is the ultimate dry solids content of the web -7% and K2 is the ultimate dry solids content +3%.
Claims16
A method in a dryer section of a paper or board machine for controlling curl of a web being dried therein to an ultimate dry solids content, the web being worked in a finishing device after the dryer section, comprising the steps of:
- while the web has a dry solids content in a range from K1 to K2 wherein K1 is the ultimate dry solids content -7% and K2 is the ultimate dry solids content +3%, guiding the web through a plurality of curl control stages in which steam is directed at the web or the web is moistened, and
- constructing the dryer section such that during at least one of said curl control stages, the temperature of the web is lower than 85.degree. C.
Dependencies are inferred from the claim text.