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3<br />
the paper is subjected to the first open<br />
draw. A Fibron transfer system with a<br />
universal P&T transfer unit and a VTT<br />
vacuum belt was installed after the press<br />
section. The P&T transfer unit takes over<br />
the paper tail fully automatically from the<br />
plain bottom press roll and transfers it<br />
into the dryer section by means of the<br />
vacuum belt.<br />
As a prerequisite for a permanent speed<br />
increase, all rotating siphons were replaced<br />
with stationary state-of-the-art<br />
ClearStar siphons for boosting steam and<br />
condensate system efficiency. The differential<br />
pressure required is much lower<br />
than with rotating siphons.<br />
In the sensitive single-tier dryer section<br />
areas, after the press section and after<br />
the size press, the existing suction rolls<br />
were lowered and equipped with DuoFoil<br />
boxes arranged above. This way, the free<br />
evaporation length of the web is extended<br />
4<br />
<strong>Paper</strong> Machines<br />
Fig. 2: DuoFormer CFD at rebuild.<br />
Fig. 3: PM 6 after start-up.<br />
Fig. 4: Scheme of ventilating doctor.<br />
considerably and the free web run is stabilized.<br />
The DuoFoil works according to<br />
the same principle as the DuoStabilizer.<br />
The only difference is that with the Duo-<br />
Foil, the box is evacuated through the<br />
suction roll arranged underneath, whereas<br />
the DuoStabilizer operates as an outside<br />
suction box for the drilled roll positioned<br />
below it.<br />
New web stabilizers were installed to<br />
achieve a more stable web run in the conventional,<br />
two-tier dryer groups of the<br />
pre-dryer section. In order to improve<br />
pocket ventilation, and consequently the<br />
CD moisture profile, the existing dryer<br />
doctors were re-built. Special <strong>Voith</strong> ventilating<br />
doctors were used which have<br />
been specifically developed for the heavier<br />
basis weights of packaging papers.<br />
The doctor back of the ventilating doctors<br />
is used as a “cross distribution pipe” and<br />
is equipped with evenly distributed holes.<br />
This way, the hot air is emitted right at<br />
41<br />
the point of highest evaporation of the<br />
web and, therefore, maximum humidity.<br />
An essential advantage of these ventilating<br />
doctors is that no major rebuilds are<br />
required in existing dryer sections. There<br />
is no need to install additional cross<br />
pipes in the very narrow pockets, since<br />
the existing doctor back can be re-built<br />
or replaced with a new doctor back in the<br />
same position (Fig. 4).<br />
These steps were taken based on the<br />
positive experiences made by Kappa Zülpich<br />
a year earlier with the same rebuilding<br />
measures in the after-dryer section.<br />
Conclusion<br />
Today, PM 6 is able to produce testliner<br />
and corrugating medium in a basis weight<br />
range of 90-140 g/m2 at 1,100 m/min.<br />
Kappa Zülpich’s well-defined optimization<br />
strategy and the good cooperation with<br />
<strong>Voith</strong> have made it possible that even<br />
seven years after installation, PM 6 still<br />
ranks among the world’s most productive<br />
machines.<br />
Kappa Zülpich is a successful example of<br />
how a company can adapt to the market’s<br />
rapid development and growing demands<br />
thanks to intelligent optimization measures<br />
and the right partner. Kappa<br />
Zülpich’s success story underlines once<br />
again that strategic optimization and<br />
close cooperation with a strong partner<br />
are key factors for boosting efficiency<br />
and increasing profitability.<br />
<strong>17</strong>/04