CPAG (2024), (стр. 19-24)
АУТОР(И) / AUTHOR(S): Juha Leimu
DOI: 10.46793/CPAG24.019L
САЖЕТАК / ABSTRACT:
Cylinder dryer runnability systems were developed to fast paper machines about forty years ago. They were needed because the running speeds exceeded 1000 m/min. The runnability was improved by arranging underpressure against the fabric and so keeping the web in contact with the fabric. Losing the contact usually means a web break. In the beginning the underpressure was created with blowing method so that a high velocity jet created the underpressure. Raising running speeds led anyway to high fan power and high electricity consumption. Aspiration to reduce the fan power led to the use of combination of suction and mechanical seals.
The whole industry has changed a lot since the systems were developed. Runnability systems are commonly used in the board machines and also with lower running speeds. This is inevitable because the raw materials and the quality of the mass are now totally different. The cost pressure is enormous and the major machine manufacturers have not done any serious development work of the runnability components in twenty years. The same problems with wearing seals continue without a vision of better sollutions.
There are possibilities to reduce the seal wearing and also more advanced technologies to avoid the contact between the seals and the fabric. They are waiting for produtization and funding. These possibilities are discussed here and a more advanced sollution is proposed.
КЉУЧНЕ РЕЧИ / KEYWORDS:
runnability systems, Cylinder dryer, seal wearing, opening nip