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Runnability Technology for Paper Machine Press and Single Felted Drying Sections

Learn about the challenges and solutions for improving runnability in the press and single felted drying sections of paper machines. This seminar covers issues such as poor machine/roll geometry, air flows and pressure differences, and web instability. Discover how EVsp and EVp web stabilizers can enhance paper quality, reduce breaks, and optimize production speed.

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Runnability Technology for Paper Machine Press and Single Felted Drying Sections

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  1. RUNNABILITY TECHNOLOGY FOR PAPER MACHINE PRESS SECTION AND SINGLE FELTED DRYING SECTION BERG SEMINAR 13-15 February 2009 Jouni Dahllund

  2. PRESS SECTION AND PRESS TRANSFER

  3. Problems at press section: Poor machine/roll geometry  too long opened and unsupported sheet draws Moving surfaces such as felts, fabrics, rolls and the web  considerable air flows and pressure differences  sheet fluttersHigh draw breaks, defects, high schrinkage and qualityproblems The sheet MD/CD strength ratio varies with an negative effect on runnability in printing.

  4. EVsp web stabilizer • eliminates blowing problems in free-standing presses • Typical problem: • Press felt pumps and produces air layer between the web and the press felt. Before the press nip occurs an air bubble causing breaks and defects. Elimination of this phenomenon to be done with excessive draw, uhle box or the web stabilizer.EVsp eliminates the blowing problem by blowing air out from the press nip and by creating vacuum between the box and press felt • vacuum by blowing • no mechanical contact to felt (no wear or damages) • sheet in contact with the press felt • EVsp does not replace the suction transfer roll, but completes its function. Speed < 800 m/min even without suction transfer roll!!

  5. EVp web stabilizer • supports the sheet from the press to the dryer section • Creates a high vacuum between the box and the dryer fabric. •  sheet in contact with the drying fabric • less breaks • low draw • easy tail threading Lower draw means also that there is less chemical pulp needed and that it is easier to achieve strength requirements.

  6. SINGLE FELTED SECTIONS

  7. PROBLEMS: • - In the beginning of the drying section, the first single felted groups are very sensitive to runThe web is still very wet and breaks easily • - Without support on web release between top cylinder and bottom roll the wet web tends to follow upper cylinder • breaks and paper defects • high draw Solution  vacuum behind the release • Air flows at web down- and uprun tend to release the web from the fabric breaks, creasing and paper wrinkles caused at upper cylinder nip • Solution  stabilizer (=vacuum) behind the fabric

  8. References of EV press- and single felted section optimization grade: copy paper, 1000 m/min After EVG modification EVp web stabilizer EVsf web stabilizers

  9. References of EV press- and single felted section optimization grade: sack paper EVsf web stabilizers EVsp web stabilizer

  10. References of EV press- and single felted section optimization EVp web stabilizer EVsf web stabilizers EVsp web stabilizer grade: cigarette and tipping paper, speed 600 m/min

  11. For superior runnability and ropeless tail threading at single felted section

  12. For superior runnability and ropeless tail threading at single felted section In EV EasyGo concept EVsf2-V Web Stabilizers are installed on top of the drilled vacuum rolls to support the sheet (stabilizer) and create a vacuum inside of the vacuum roll (suction). This box has two air connections i.e. blow and suction. Drilling of the cylinders on site without cylinder remove enables minimal downtime.

  13. Excellent runnability of the drying section • Ropeless tail threading • Additional PM speed • Fewer breaks and less time required for tail threading: Additional production time • Improved paper quality • Drilled holes of the vacuum rolls are big enough to prevent clogging (Ø6…8 mm) • Cost-effective investment, short pay-back time • No fabric contact • Drilling of the cylinders easier and less expensive than exhausting from the cylinder heads: no grooving and change of cylinder heads and bearings mean also • minimized down time

  14. References of EV EasyGo concept Burgo Villorba, PM 8 in Italy - LWC, speed 1500 m/min, width 4,5 m After EV Drying section optimization 3 x EVsf2-V web stabilizers EV Cleaner 15 x EVdf web stabilizers

  15. References of EV EasyGo concept Cartiere Miliani Fabriano, PM 3, Italy, copy paper, speed 1100 m/min, width 4,5 m After EV Drying section optimization EVdf web stabilizers EVdf web stabilizers EVsf2-V web stabilizers Ropeless tail feeding with TailBlades

  16. NEW TECHNOLOGY FOR THE FIRST DRYING SECTION GROUPS TO OPTIMIZE WEB RELEASE BETWEEN UPPER CYLINDER AND VACUUM ROLL

  17. technology with EVsf3-V Web Stabilizer: • High release vacuum zone • Ensures optimal sheet release from • upper cylinder • Eliminates sheet flutter and paper defects

  18. High release vacuum Normal vacuum Normal vacuum

  19. VACUUM WITH DIFFERENT AIR PRESSURE Nozzle distance to fabric 4-8 mm VACUUM AT HIGH PRESSURE AREA [Pa] PRESSURE AT NOZZLE [bar]

  20. THANK YOU!

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