Presentation on theme: "BERG SEMINAR 13-15 February 2009 RUNNABILITY TECHNOLOGY FOR PAPER MACHINE PRESS SECTION AND SINGLE FELTED DRYING SECTION BERG SEMINAR 13-15 February 2009."— Presentation transcript:
BERG SEMINAR February 2009 RUNNABILITY TECHNOLOGY FOR PAPER MACHINE PRESS SECTION AND SINGLE FELTED DRYING SECTION BERG SEMINAR February 2009 Jouni Dahllund
BERG SEMINAR February 2009 PRESS SECTION AND PRESS TRANSFER
BERG SEMINAR February 2009 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 flutters High draw breaks, defects, high schrinkage and quality problems The sheet MD/CD strength ratio varies with an negative effect on runnability in printing.
BERG SEMINAR February 2009 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!!
BERG SEMINAR February 2009 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.
BERG SEMINAR February 2009 SINGLE FELTED SECTIONS
- 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 PROBLEMS:
BERG SEMINAR February 2009 After EVG modification EVsf web stabilizers EVp web stabilizer grade: copy paper, 1000 m/min References of EV press- and single felted section optimization
BERG SEMINAR February 2009 grade: sack paper EVsf web stabilizers EVsp web stabilizer References of EV press- and single felted section optimization
BERG SEMINAR February 2009 EVsf web stabilizers EVp web stabilizer EVsp web stabilizer grade: cigarette and tipping paper, speed 600 m/min References of EV press- and single felted section optimization
BERG SEMINAR February 2009 For superior runnability and ropeless tail threading at single felted section
BERG SEMINAR February 2009 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.
BERG SEMINAR February 2009 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
BERG SEMINAR February 2009 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 15 x EVdf web stabilizers EV Cleaner References of EV EasyGo concept
BERG SEMINAR February 2009 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 EVsf2-V web stabilizers Ropeless tail feeding with TailBlades EVdf web stabilizers
NEW TECHNOLOGY FOR THE FIRST DRYING SECTION GROUPS TO OPTIMIZE WEB RELEASE BETWEEN UPPER CYLINDER AND VACUUM ROLL
BERG SEMINAR February 2009 technology with EVsf3-V Web Stabilizer: - High release vacuum zone - Ensures optimal sheet release from upper cylinder - Eliminates sheet flutter and paper defects
BERG SEMINAR February 2009 High release vacuum Normal vacuum
BERG SEMINAR February 2009 VACUUM WITH DIFFERENT AIR PRESSURE VACUUM AT HIGH PRESSURE AREA [Pa] PRESSURE AT NOZZLE [bar] Nozzle distance to fabric 4-8 mm