System for keeping calender rolls of a paper machine clean

A method for maintaining calender rolls of a paper machine clean when producing high-gloss paper or coated paper, the method comprising the steps of:

• drying a paper web in a dryer section;
• coating the paper web in a coating station;
• drying the paper web in an additional dryer section;
• measuring the paper web in a first measuring station;
• calendering the web in a multi-nip on-line calender having a plurality of calender rolls;
• reeling the paper web in a reeling unit, and passing the paper web from the dryer section to the coating station to the additional dryer section, to the first measuring station, to the calender, and then to the reeling unit;
• measuring the paper web in a second measurement station with measuring and indicator means and producing an output indicating the soiledness of the web or a humidity profile in a transverse CD direction;
• preventing coating dye from adhering onto a smooth surface of a calender roll and thus preventing the smooth surface of said calender roll from becoming soiled and thus also preventing an overheating phenomenon and an extra heat-transfer resistance of a thermoroll by detecting an output of the second measurement station which indicates excessive soiledness or uneven humidity profile and in response to said detected output performing at least one function selected from the group consisting of:
• cleaning the surface of a smooth-surfaced calender roll of the calender;
• changing the nip load in the calender;
• making a correction adjustment of the CD-directional humidity profile of the web;
• cutting the web and conducting it into a pulper;
• and
• changing the running speed of the web.

A method for maintaining calender rolls of a paper machine clean when producing coated paper, the method comprising:

• drying a paper web in a dryer section;
• coating the paper web in a coating station, to form a coated web;
• further drying the coated web in an additional dryer section;
• measuring in a first measuring station a parameter of the coated web before a last dryer group of the additional dryer section;
• measuring in a second measuring station a parameter of the coated web indicating excessive soiledness or an uneven humidity profile in the web, the measuring taking place before a multi-nip on-line calender having a plurality of calender rolls, and in response to said detected output, preventing coating dye from adhering onto a smooth surface of a calender roll by performing at least one function selected from the group consisting of:
• cleaning the surface of a smooth-surfaced calender roll of the plurality of calender rolls of the calender;
• changing the nip load in the calender;
• making a correction adjustment of the CD-directional humidity profile of the web;
• cutting the web and conducting it into a pulper;
• and
• changing the running speed of the web;
• and
• further comprising the step of:
• when the paper passes through the calender winding it on a reel following the calender.