Paper Technology International 2020 - Journal - Page 52

PAPERTECHNOLOGYINTERNATIONAL
Atronet.P – tailor made for pulp. Franz Kiefer, Strategic Product Manager Pressing, Heimbach GmbH
INTRODUCTION:
Before bales of pulp make their journey to paper mills across the world, pulp manufacturers have already put in a great deal of work.
Pressing the water out of a fibrous mass and then drying it is an impressive feat.The forces at work here are in no way inferior to those in
the paper machine. For this reason, specialised and highly resilient press felts are required. These also come from Heimbach.
A little bit of pulp science
In terms of volume, waste paper is by far the most important
raw material for the paper industry. However, the quality demands of
some consumers mean that pulp is also needed for many types of
paper and board. Pulp is really a fantastic product, sustainable and
environmentally friendly.
It is created by the chemical pulping of plant fibres, and
consists mainly of cellulose. 90 per cent of all pulp produced globally
is made from wood. Here, the yield is about 50 per cent, depending
on the variety.
The originally wet suspension must be dried as thoroughly
as possible before transport. The equipment used for this is very
similar in structure to a paper machine.There is a wire section, press
section and a dryer section. In the last section, however, drying is
carried out via a hot air process,so there is no need for dryer fabrics.
Figure 1: Pulp bale.
Caution, hot!
When the pulp is dewatered, the basis
weight of the web (800-1500 g/m²) is much higher
than in paper or board production. The production
speed (150-200 m/min) is correspondingly lower.
Particularly challenging for the clothing
on these applications are the very high fabric
temperatures which are required to enable effective
dewatering in the press section. At the beginning
of the press section in particular, the fabrics are
subjected to very high thermal stress and can
shrink or even collapse as a result. With this in
mind, Heimbach has developed specialised felts for
the pulp industry.
© HEINZEL Group
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