Web stabilizers, pocket ventilation and machine geometry modifications eliminate runnability problems efficiently and are often required to ensure fluent paper making process in the press and dryer sections. These maintenance free solutions have a huge impact on drying and energy costs.
Especially in high-speed paper machines, the first single-felted groups are very sensitive to run. Still very wet, the web stretches and breaks easily. Moving surfaces, like cylinders, rolls and drying fabrics, cause air flows and pressure differences, especially in the nips, reducing dryer section runnability. This can lead to sheet fluttering, breaks, complicated tail threading and paper quality problems, such as edge flipping or wrinkles. Without high-vacuum support, the wet web tends to follow the upper cylinder, resulting in breaks and paper defects.
Traditional runnability control with increased draw not only reduces sheet strength and quality but easily causes breaks in the dryer section, finishing processes and later in printing presses, too. A high draw difference means additional raw material costs, as more chemical pulp is required to improve sheet strength.
Reducing the draw provides the potential to increase machine speed and optimize furnish. The RunPro EasyOne web stabilizer optimizes the web release with a special high-vacuum system during the critical sheet release between the upper cylinder and the vacuum roll. It prevents the web from following the upper cylinder, resulting in fewer breaks and defects.
When designing RunPro EasyOne, traditional air nozzles and mechanical seals across the machine have been replaced by pivoting high-release, non-contact nozzles. In critical opening nips, the nozzles bend and do not break the fabric if a paper jam occurs. Air is blown with high speed through the high-release nozzles against the fabric’s running direction. Thanks to the combination of the geometry, the construction of the stabilizer and the dynamic forces created by the air flows, a negative pressure is created in the opening nip towards the release point. This negative pressure ensures that the web sticks to the felt and not to the cylinder surface. The special and patented design is very robust. Possible paper jams and wear part consumption are significantly reduced.
Web Stabilizer to improve runnability and efficiency in a free-standing press
Web Stabilizer to support the sheet from the press to the drying section
Maximum draw reduction is achieved with AirCurtain for center roll sheet release.
EasyOne concept – Optimized web release with a special high vacuum area at the critical sheet release point between the upper cylinder and the vacuum roll.
The increased compressure energy requirement for the high release nozzles will be compensated by the cost savings: The reduced number of web breaks and the reduced time required for cleaning work and tail threading following the web break.
The negative pressure level required on the dryer fabric side of the opening nip is highly dependent on the production speed. The negative pressure must exceed the pressure on the paper run side, thus making the paper web to follow the fabric instead of the smooth cylinder surface.
High release nozzle technology of the EasyOne enables the required under pressure levels without edge or cross direction nozzles. Thus, there is no further need to blow hot supply air to the stabilizer saving a great deal of energy. Moreover, the construction is maintenance free enabling 100% efficiency without any service requirements to the web stabilizers.
In addition to the reduced running costs, the development means lower investment costs for any traditional air system equipment or lay-out demands.
Web Stabilizer to support the sheet run and to ventilate the cylinder pocket
Reduced unsupported draw by 25 – 50% between the top and bottom dryers enables trouble free runnability and supported ropeless tail threading.
The stabilizer gives better drying capacity due to reduced pocket humidity levels and wider sheet wrap against the drying cylinders.
Significant energy saving is guaranteed with optimized pocket ventilation by decreasing the pocket humidity level, correcting the pocket moisture profiles and eliminating the need for over-drying.
The pocket ventilators are installed near the felt rolls blowing dry supply air in to the pockets.
Paper Machine Runnability and Tail threading RunPro
Runnability orientated RunPro offers web stabilizing, machine geometry modifications and ropeless tail threading solutions to eliminate runnability problems and to ensure fluent paper making process.
Web stabilizing and tail threading solutions are safe, reliable and maintenance free resulting in significant benefits that are reflected in a minimal payback time.
Runtech Systems is a global provider of engineered systems tailored to the pulp and paper industries. Runtech works with customers to better understand and control their operational conditions to maximize efficiency and cost effectiveness. Our main target is to bring notable energy savings and highly improved process efficiency for board, tissue and paper mills.
Runtech's patented solutions include energy efficient vacuum system and heat recovery optimization, runnability optimization, dewatering, doctoring and cleanliness optimization as well as ropeless tail threading, including related services, spare parts and paper machine audits and consulting.