Paper Technology International 2020 - Journal - Page 39

PAPERTECHNOLOGYINTERNATIONAL
Find the bottlenecks and machine potential
Good runnability means continuous machine operation with
minimal web breaks, while machine productivity and the amount of waste
stay at the desired level.
Papermakers are often faced with various runnability issues.
These include a high number of web breaks or problems with tail
threading or end product quality. Or perhaps there is a need to increase
the machine speed but no knowledge of how to eliminate possible
runnability issues in the dryer section. Or the speed has already
increased, but there are now too many web breaks on the machine.
Runnability issues can be solved. The very first step to improve
machine runnability is to extensively analyze the process factors from
the wet end to the reel. A comprehensive runnability and efficiency audit
performed by Runtech professionals can help you identify your machine
bottlenecks as well as discover much needed improvement potential.
The aim of a drying section audit is to analyze and effectively
decrease energy consumption while improving drying capacity and
runnability. The audit consists of pocket humidity and temperature
measurements, cylinder surface and sheet temperature measurements,
the calculation of drying parameters, hood air system analysis,
mechanical checking and heat recovery efficiency measurements.
A tail threading audit can identify tail threading issues as well as
help operators improve safety and shorten tail threading time. This audit
can be conducted on a single specific area/component, multiple areas/
components or on the whole machine.
Figure 4: Pocket humidity levels are measured as a part of the
drying section audit.
Figure 5: With correct pocket
ventilation the pocket is kept
hot and dry to maximize drying
efficiency, lower drying costs
and increase production. Upper
nozzle prevents humid air flow
entering the pocket (A) and lower
nozzle blows dry supply air into
the pocket (B). Humid air exits the
pocket (C).
Upper nozzle – lower nozzle (D)
form a long distance overpressure
area to provide sufficient air flow
to the pockets. All air from pocket
ventilators is blowing to the
pockets.
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